P2X7 receptor blockade protects against cisplatin-induced nephrotoxicity in mice by decreasing the activities of inflammasome components, oxidative stress and caspase-3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yuanyuan; Yuan, Fahuan; Cao, Xuejiao

2014-11-15

Nephrotoxicity is a common complication of cisplatin chemotherapy and thus limits the use of cisplatin in clinic. The purinergic 2X7 receptor (P2X7R) plays important roles in inflammation and apoptosis in some inflammatory diseases; however, its roles in cisplatin-induced nephrotoxicity remain unclear. In this study, we first assessed the expression of P2X7R in cisplatin-induced nephrotoxicity in C57BL/6 mice, and then we investigated the changes of renal function, histological injury, inflammatory response, and apoptosis in renal tissues after P2X7R blockade in vivo using an antagonist A-438079. Moreover, we measured the changes of nod-like receptor family, pyrin domain containing proteins (NLRP3) inflammasome components,more » oxidative stress, and proapoptotic genes in renal tissues in cisplatin-induced nephrotoxicity after treatment with A-438079. We found that the expression of P2X7R was significantly upregulated in the renal tubular epithelial cells in cisplatin-induced nephrotoxicity compared with that of the normal control group. Furthermore, pretreatment with A-438079 markedly attenuated the cisplatin-induced renal injury while lightening the histological damage, inflammatory response and apoptosis in renal tissue, and improved the renal function. These effects were associated with the significantly reduced levels of NLRP3 inflammasome components, oxidative stress, p53 and caspase-3 in renal tissues in cisplatin-induced nephrotoxicity. In conclusions, our studies suggest that the upregulated activity of P2X7R might play important roles in the development of cisplatin-induced nephrotoxicity, and P2X7R blockade might become an effective therapeutic strategy for this disease. - Highlights: • The P2X7R expression was markedly upregulated in cisplatin-induced nephrotoxicity. • P2X7R blockade significantly attenuated the cisplatin-induced renal injury. • P2X7R blockade reduced activities of NLRP3 inflammasome components in renal tissue. • P2X7R blockade reduced levels of oxidative stress and apoptosis in renal tissue. • P2X7R blockade may be a novel adjunctive therapy strategy for this disease.« less

Effects of acute and subchronic AT1 receptor blockade on cardiovascular, hydromineral and neuroendocrine responses in female rats.

PubMed

Araujo, Iracema Gomes; Elias, Lucila Leico Kagohara; Antunes-Rodrigues, José; Reis, Luís Carlos; Mecawi, Andre Souza

2013-10-02

Female Wistar rats were ovariectomized (OVX) and separated into two groups that received either estradiol cypionate (EC, 40 μg/kg, sc; OVX-EC) or vehicle (corn oil, sc; OVX-oil) for 14 consecutive days. On the 7th day of treatment, a subset of animals from both the OVX-oil and OVX-EC groups was subjected to subchronic losartan (AT1 receptor antagonist) treatment (0.1g/L in drinking water; ~15 mg/kg/day) for 7 days. Other group of OVX-oil and OVX-EC rats was submitted to an acute losartan injection (100mg/kg, ip) on the 14th day of hormone replacement. In both protocols, the following parameters were measured: I) mean arterial pressure (MAP) and heart rate (HR); II) water and 0.3M saline intake; III) angiotensin II (ANG II), atrial natriuretic peptide (ANP), vasopressin (AVP) and oxytocin (OT) plasma concentrations; and IV) urinary and plasma sodium concentrations. Acute AT1 blockade induced a significant reduction in the MAP in the OVX rats, resulting in increased HR and water intake, which were attenuated by estradiol therapy. Acute AT1 blockade also increased ANG II and OT and reduced ANP plasma concentrations, with no changes in AVP secretion. In addition, acute hypotension was accompanied by a decrease in natriuresis, which was unaltered by estradiol. Subchronic AT1 blockade induced a significant decrease in MAP without changing HR in both groups. Additionally, subchronic losartan treatment induced sodium appetite in OVX rats. Prolonged AT1 blockade increased ANG II and AVP and reduced ANP plasma concentrations. Moreover, it increased natriuresis but did not alter plasma OT concentrations. Finally, estradiol treatment attenuated the increase in salt intake and plasma ANG II concentrations induced by subchronic AT1 blockade. In conclusion, our results suggest differential adaptive responses to the acute or subchronic losartan treatment in OVX and OVX-EC rats. © 2013.

BLOCKADE OF TRKA OR P75 NEUROTROPHIN RECEPTORS ATTENUATES DIESEL PARTICULATE-INDUCED ENHANCEMENT OF ALLERGIC AIRWAYS RESPONSES IN BALB/C MICE

EPA Science Inventory

Neurotrophins, including nerve growth factor (NGF) partially mediate many features of allergic airways disease including airway resistance. Exposure to diesel exhaust particles (DEP) associated with the combustion of diesel fuel exacerbates allergic airways responses. We tested t...

Dopamine D3 receptor antagonist SB-277011A inhibits methamphetamine self-administration and methamphetamine-induced reinstatement of drug-seeking in rats

PubMed Central

Higley, Amanda E.; Kiefer, Stephen W.; Li, Xia; Gaál, József; Xi, Zheng-Xiong; Gardner, Eliot L.

2013-01-01

We have previously reported that selective blockade of brain dopamine D3 receptors by SB-277011A significantly attenuates cocaine self-administration and cocaine-induced reinstatement of drug-seeking behavior. In the present study, we investigated whether SB-277011A similarly inhibits methamphetamine self-administration and methamphetamine-induced reinstatement to drug-seeking behavior. Male Long–Evans rats were allowed to intravenously self-administer methamphetamine (0.05 mg/kg/infusion) under fixed-ratio 2 (FR2) or progressive-ratio (PR) reinforcement conditions, and some rats were tested for methamphetamine-induced reinstatement of drug-seeking behavior after extinction of self-administration. The effects of SB-277011A on each of these methamphetamine-supported behaviors were then tested. Acute intraperitoneal (i.p.) administration of SB-277011A failed to alter methamphetamine self-administration under FR2 reinforcement, but significantly lowered the break-point for methamphetamine self-administration under PR reinforcement. SB-277011A also significantly inhibited methamphetamine-triggered reinstatement of extinguished drug-seeking behavior. Overall, these data show that blockade of dopamine D3 receptors by SB-277011A attenuates the rewarding and incentive motivational effects of methamphetamine in rats, supporting the development of selective dopamine D3 antagonists for the treatment of methamphetamine addiction. PMID:21466803

5HT2A receptor blockade in dorsomedial striatum reduces repetitive behaviors in BTBR mice.

PubMed

Amodeo, D A; Rivera, E; Cook, E H; Sweeney, J A; Ragozzino, M E

2017-03-01

Restricted and repetitive behaviors are a defining feature of autism, which can be expressed as a cognitive flexibility deficit or stereotyped, motor behaviors. There is limited knowledge about the underlying neuropathophysiology contributing to these behaviors. Previous findings suggest that central 5HT 2A receptor activity is altered in autism, while recent work indicates that systemic 5HT 2A receptor antagonist treatment reduces repetitive behaviors in an idiopathic model of autism. 5HT 2A receptors are expressed in the orbitofrontal cortex and striatum. These two regions have been shown to be altered in autism. The present study investigated whether 5HT 2A receptor blockade in the dorsomedial striatum or orbitofrontal cortex in the BTBR mouse strain, an idiopathic model of autism, affects the phenotype related to restricted and repetitive behaviors. Microinfusion of the 5HT 2A receptor antagonist, M100907 into the dorsomedial striatum alleviated a reversal learning impairment and attenuated grooming behavior. M100907 infusion into the orbitofrontal cortex increased perseveration during reversal learning and potentiated grooming. These findings suggest that increased 5HT 2A receptor activity in the dorsomedial striatum may contribute to behavioral inflexibility and stereotyped behaviors in the BTBR mouse. 5HT 2A receptor signaling in the orbitofrontal cortex may be critical for inhibiting a previously learned response during reversal learning and expression of stereotyped behavior. The present results suggest which brain areas exhibit abnormalities underlying repetitive behaviors in an idiopathic mouse model of autism, as well as which brain areas systemic treatment with M100907 may principally act on in BTBR mice to attenuate repetitive behaviors. © 2016 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

NK1 receptor activation in rat rostral ventrolateral medulla selectively attenuates somato-sympathetic reflex while antagonism attenuates sympathetic chemoreflex.

PubMed

Makeham, John M; Goodchild, Ann K; Pilowsky, Paul M

2005-06-01

The effects of activation and blockade of the neurokinin 1 (NK1) receptor in the rostral ventrolateral medulla (RVLM) on arterial blood pressure (ABP), splanchnic sympathetic nerve activity (sSNA), phrenic nerve activity, the somato-sympathetic reflex, baroreflex, and chemoreflex were studied in urethane-anesthetized and artificially ventilated Sprague-Dawley rats. Bilateral microinjection of either the stable substance P analog (pGlu5, MePhe8, Sar9)SP(5-11) (DiMe-SP) or the highly selective NK1 agonist [Sar9, Met (O(2))11]SP into the RVLM resulted in an increase in ABP, sSNA, and heart rate and an abolition of phrenic nerve activity. The effects of [Sar9, Met (O(2))11]SP were blocked by the selective nonpeptide NK1 receptor antagonist WIN 51708. NK1 receptor activation also dramatically attenuated the somato-sympathetic reflex elicited by tibial nerve stimulation, while leaving the baroreflex and chemoreflex unaffected. This effect was again blocked by WIN 51708. NK1 receptor antagonism in the RVLM, with WIN 51708 significantly attenuated the sympathoexcitatory response to hypoxia but had no effect on baseline respiratory function. Our findings suggest that substance P and the NK1 receptor play a significant role in the cardiorespiratory reflexes integrated within the RVLM.

Blockade of neuronal dopamine D2 receptor attenuates morphine tolerance in mice spinal cord.

PubMed

Dai, Wen-Ling; Xiong, Feng; Yan, Bing; Cao, Zheng-Yu; Liu, Wen-Tao; Liu, Ji-Hua; Yu, Bo-Yang

2016-12-22

Tolerance induced by morphine remains a major unresolved problem and significantly limits its clinical use. Recent evidences have indicated that dopamine D2 receptor (D2DR) is likely to be involved in morphine-induced antinociceptive tolerance. However, its exact effect and molecular mechanism remain unknown. In this study we examined the effect of D2DR on morphine antinociceptive tolerance in mice spinal cord. Chronic morphine treatment significantly increased levels of D2DR in mice spinal dorsal horn. And the immunoreactivity of D2DR was newly expressed in neurons rather than astrocytes or microglia both in vivo and in vitro. Blockade of D2DR with its antagonist (sulpiride and L-741,626, i.t.) attenuated morphine antinociceptive tolerance without affecting basal pain perception. Sulpiride (i.t.) also down-regulated the expression of phosphorylation of NR1, PKC, MAPKs and suppressed the activation of astrocytes and microglia induced by chronic morphine administration. Particularly, D2DR was found to interact with μ opioid receptor (MOR) in neurons, and chronic morphine treatment enhanced the MOR/D2DR interactions. Sulpiride (i.t.) could disrupt the MOR/D2DR interactions and attenuate morphine tolerance, indicating that neuronal D2DR in the spinal cord may be involved in morphine tolerance possibly by interacting with MOR. These results may present new opportunities for the treatment and management of morphine-induced antinociceptive tolerance which often observed in clinic.

Blockade of interferon Beta, but not interferon alpha, signaling controls persistent viral infection.

PubMed

Ng, Cherie T; Sullivan, Brian M; Teijaro, John R; Lee, Andrew M; Welch, Megan; Rice, Stephanie; Sheehan, Kathleen C F; Schreiber, Robert D; Oldstone, Michael B A

2015-05-13

Although type I interferon (IFN-I) is thought to be beneficial against microbial infections, persistent viral infections are characterized by high interferon signatures suggesting that IFN-I signaling may promote disease pathogenesis. During persistent lymphocytic choriomeningitis virus (LCMV) infection, IFNα and IFNβ are highly induced early after infection, and blocking IFN-I receptor (IFNAR) signaling promotes virus clearance. We assessed the specific roles of IFNβ versus IFNα in controlling LCMV infection. While blockade of IFNβ alone does not alter early viral dissemination, it is important in determining lymphoid structure, lymphocyte migration, and anti-viral T cell responses that lead to accelerated virus clearance, approximating what occurs during attenuation of IFNAR signaling. Comparatively, blockade of IFNα was not associated with improved viral control, but with early dissemination of virus. Thus, despite their use of the same receptor, IFNβ and IFNα have unique and distinguishable biologic functions, with IFNβ being mainly responsible for promoting viral persistence. Copyright © 2015 Elsevier Inc. All rights reserved.

Acute Bradykinin Receptor Blockade During Hemorrhagic Shock in Mice Prevents the Worsening Hypotensive Effect of Angiotensin-Converting Enzyme Inhibitor.

PubMed

Charbonneau, Hélène; Buléon, Marie; Minville, Vincent; Faguer, Stanislas; Girolami, Jean-Pierre; Bascands, Jean-Loup; Tack, Ivan; Mayeur, Nicolas

2016-09-01

Angiotensin-converting enzyme inhibitors are associated with deleterious hypotension during anesthesia and shock. Because the pharmacologic effects of angiotensin-converting enzyme inhibitors are partly mediated by increased bradykinin B2 receptor activation, this study aimed to determine the impact of acute B2 receptor blockade during hemorrhagic shock in angiotensin-converting enzyme inhibitor-treated mice. In vivo study. University research unit. C57/Bl6 mice. The hemodynamic effect of B2 receptor blockade using icatibant (B2 receptor antagonist) was studied using a pressure-targeted hemorrhagic shock and a volume-targeted hemorrhagic shock. Animals were anesthetized with ketamine and xylazine (250 mg/kg and 10 mg/kg, respectively), intubated using intratracheal cannula, and ventilated (9 mL/kg, 150 min). Five groups were studied: 1) sham-operated animals, 2) control shocked mice, 3) shocked mice treated with ramipril for 7 days (angiotensin-converting enzyme inhibitors) before hemorrhagic shock, 4) shocked mice treated with angiotensin-converting enzyme inhibitors and a single bolus of icatibant (HOE-140) immediately before anesthesia (angiotensin-converting enzyme inhibitors + icatibant), and 5) shocked mice treated with a single bolus of icatibant. One hour after volume-targeted hemorrhagic shock, blood lactate was measured to evaluate organ failure. During pressure-targeted hemorrhagic shock, the mean blood volume withdrawn was significantly lower in the angiotensin-converting enzyme inhibitor group than in the other groups (p < 0.001). During volume-targeted hemorrhagic shock, icatibant prevented blood pressure lowering in the angiotensin-converting enzyme inhibitor group (p < 0.001). Blood lactate was significantly higher in the angiotensin-converting enzyme inhibitor group than in the other groups, particularly the HOE groups. During hemorrhagic shock, acute B2 receptor blockade significantly attenuates the deleterious hemodynamic effect of angiotensin-converting enzyme inhibitor treatment in mice. This beneficial effect of B2 receptor blockade is rapidly reached and sustained with a single bolus of icatibant. This benefit could be of interest in angiotensin-converting enzyme inhibitor-treated patients during both emergency anesthesia and resuscitation.

Histaminergic Receptors Modulate Spinal Cord Injury-Induced Neuronal Nitric Oxide Synthase Upregulation and Cord Pathology: New Roles of Nanowired Drug Delivery for Neuroprotection.

PubMed

Sharma, Hari S; Patnaik, Ranjana; Muresanu, Dafin F; Lafuente, José V; Ozkizilcik, Asya; Tian, Z Ryan; Nozari, Ala; Sharma, Aruna

2017-01-01

The possibility that histamine influences the spinal cord pathophysiology following trauma through specific receptor-mediated upregulation of neuronal nitric oxide synthase (nNOS) was examined in a rat model. A focal spinal cord injury (SCI) was inflicted by a longitudinal incision into the right dorsal horn of the T10-11 segments. The animals were allowed to survive 5h. The SCI significantly induced breakdown of the blood-spinal cord barrier to protein tracers, reduced the spinal cord blood flow at 5h, and increased the edema formation and massive upregulation of nNOS expression. Pretreatment with histamine H1 receptor antagonist mepyramine (1mg, 5mg, and 10mg/kg, i.p., 30min before injury) failed to attenuate nNOS expression and spinal cord pathology following SCI. On the other hand, blockade of histamine H2 receptors with cimetidine or ranitidine (1mg, 5mg, or 10mg/kg) significantly reduced these early pathophysiological events and attenuated nNOS expression in a dose-dependent manner. Interestingly, TiO 2 -naowire delivery of cimetidine or ranitidine (5mg doses) exerted superior neuroprotective effects on SCI-induced nNOS expression and cord pathology. It appears that effects of ranitidine were far superior than cimetidine at identical doses in SCI. On the other hand, pretreatment with histamine H3 receptor agonist α-methylhistamine (1mg, 2mg, or 5mg/kg, i.p.) that inhibits histamine synthesis and release in the central nervous system thwarted the spinal cord pathophysiology and nNOS expression when used in lower doses. Interestingly, histamine H3 receptor antagonist thioperamide (1mg, 2mg, or 5mg/kg, i.p.) exacerbated nNOS expression and cord pathology after SCI. These novel observations suggest that blockade of histamine H2 receptors or stimulation of histamine H3 receptors attenuates nNOS expression and induces neuroprotection in SCI. Taken together, our results are the first to demonstrate that histamine-induced pathophysiology of SCI is mediated via nNOS expression involving specific histamine receptors. © 2017 Elsevier Inc. All rights reserved.

Blockade of P2X7 receptors or pannexin-1 channels similarly attenuates postischemic damage.

PubMed

Cisneros-Mejorado, Abraham; Gottlieb, Miroslav; Cavaliere, Fabio; Magnus, Tim; Koch-Nolte, Friederich; Scemes, Eliana; Pérez-Samartín, Alberto; Matute, Carlos

2015-05-01

The role of P2X7 receptors and pannexin-1 channels in ischemic damage remains controversial. Here, we analyzed their contribution to postanoxic depolarization after ischemia in cultured neurons and in brain slices. We observed that pharmacological blockade of P2X7 receptors or pannexin-1 channels delayed the onset of postanoxic currents and reduced their slope, and that simultaneous inhibition did not further enhance the effects of blocking either one. These results were confirmed in acute cortical slices from P2X7 and pannexin-1 knockout mice. Oxygen-glucose deprivation in cortical organotypic cultures caused neuronal death that was reduced with P2X7 and pannexin-1 blockers as well as in organotypic cultures derived from mice lacking P2X7 and pannexin 1. Subsequently, we used transient middle cerebral artery occlusion to monitor the neuroprotective effect of those drugs in vivo. We found that P2X7 and pannexin-1 antagonists, and their ablation in knockout mice, substantially attenuated the motor symptoms and reduced the infarct volume to ~50% of that in vehicle-treated or wild-type animals. These results show that P2X7 receptors and pannexin-1 channels are major mediators of postanoxic depolarization in neurons and of brain damage after ischemia, and that they operate in the same deleterious signaling cascade leading to neuronal and tissue demise.

Selective Blockade of Herpesvirus Entry Mediator–B and T Lymphocyte Attenuator Pathway Ameliorates Acute Graft-versus-Host Reaction

PubMed Central

del Rio, Maria-Luisa; Jones, Nick D.; Buhler, Leo; Norris, Paula; Shintani, Yasushi; Ware, Carl F.; Rodriguez-Barbosa, Jose-Ignacio

2013-01-01

The cosignaling network mediated by the herpesvirus entry mediator (HVEM; TNFRSF14) functions as a dual directional system that involves proinflammatory ligand, lymphotoxin that exhibits inducible expression and competes with HSV glycoprotein D for HVEM, a receptor expressed by T lymphocytes (LIGHT; TNFSF14), and the inhibitory Ig family member B and T lymphocyte attenuator (BTLA). To dissect the differential contributions of HVEM/BTLA and HVEM/LIGHT interactions, topographically-specific, competitive, and nonblocking anti-HVEM Abs that inhibit BTLA binding, but not LIGHT, were developed. We demonstrate that a BTLA-specific competitor attenuated the course of acute graft-versus-host reaction in a murine F1 transfer semiallogeneic model. Selective HVEM/BTLA blockade did not inhibit donor T cell infiltration into graft-versus-host reaction target organs, but decreased the functional activity of the alloreactive T cells. These results highlight the critical role of HVEM/BTLA pathway in the control of the allogeneic immune response and identify a new therapeutic target for transplantation and autoimmune diseases. PMID:22490863

The effect of dopamine receptor blockade in the rodent nucleus accumbens on local field potential oscillations and motor activity in response to ketamine.

PubMed

Matulewicz, Pawel; Kasicki, Stefan; Hunt, Mark Jeremy

2010-12-17

Altered functioning of the nucleus accumbens (NAc) has been implicated in the psychotomimetic actions of NMDA receptor (NMDAR) antagonists and the pathophysiology of schizophrenia. We have shown previously that NMDAR antagonists enhance the power of high-frequency oscillations (HFO) in the NAc in a dose-dependent manner, as well as increase locomotor activity. Systemic administration of NMDAR antagonists is known to increase the release of dopamine in the NAc and dopamine antagonists can reduce ketamine-induced hyperactivity. In this study, we examined the effect of 0.5 μl intra-NAc infusion of 3.2 μg SCH23390 (D1 antagonist), 10 μg raclopride (D2 antagonist) and saline on ketamine-induced changes in motor and oscillatory activity. We found that local blockade of D1 receptors attenuated ketamine-induced increases in motor activity and blockade of D2 receptors produced a much weaker effect, with respect to saline-infused control groups. In contrast, none of the antagonists, infused separately or together, significantly modified the power or dominant frequency of ketamine-induced increases in HFO, but changes in delta and theta frequency bands were observed. Together, these findings suggest, that, in contrast to delta and theta frequency bands, the generation of ketamine enhanced-HFO in the NAc is not causally related to locomotor activation and occurs largely independently of local changes in dopamine receptor activation. Copyright © 2010 Elsevier B.V. All rights reserved.

Cisplatin-Induced Conditioned Taste Aversion: Attenuation by Dexamethasone but not Zacopride or GR38032F

DTIC Science & Technology

1992-01-01

SR2-1 Cisplatin-induced conditioned taste aversion: ateuto by dexamethasone but not zacopride or GR38032F Nm I- Paul C Mele, John R. McDonough, David...to 5-H1’, receptor blockade. 5-HT., receptor antagonists; Zacopridc: GR38032F; Desamethasone: Cisplatin: Taste aversion (conditioned) I. Introductlon...intake) was used as the area known as the chemoreceptor trigger zone (Borri- index of the CTA. son, 1974). Moreover. the findings that rats, ferrets

The role of prostaglandins in spinal transmission of the exercise pressor reflex in decerebrate rats

PubMed Central

Stone, Audrey J.; Copp, Steven W.; Kaufman, Marc P.

2014-01-01

Previous studies found that prostaglandins in skeletal muscle play a role in evoking the exercise pressor reflex; however the role played by prostaglandins in the spinal transmission of the reflex is not known. We determined, therefore, whether or not spinal blockade of cyclooxygenase (COX) activity and/or spinal blockade of endoperoxide receptor (EP) 2 or EP4 receptors attenuated the exercise pressor reflex in decerebrate rats. We first established that intrathecal doses of a non-specific COX inhibitor Ketorolac (100ug in 10ul), a COX-2 specific inhibitor Celecoxib (100μg in 10μl), an EP2 antagonist PF-04418948 (10μg in 10μl), and an EP4 antagonist L-161,982 (4μg in 10μl) effectively attenuated the pressor responses to intrathecal injections of Arachidonic Acid (100μg in 10μl), EP2 agonist Butaprost (4ng in 10 μl), and EP4 agonist TCS 2510 (6.25μg in 2.5 μl), respectively. Once effective doses were established, we statically contracted the hindlimb before and after intrathecal injections of Ketorolac, Celecoxib, the EP2 antagonist and the EP4 antagonist. We found that Ketorolac significantly attenuated the pressor response to static contraction (before Ketorolac: 23±5 mmHg, after Ketorolac 14±5 mmHg; p<0.05) whereas Celecoxib had no effect. We also found that 8μg of L-161,982, but not 4 μg of L-161,982, significantly attenuated the pressor response to static contraction (before L-161,982: 21±4 mmHg, after L-161,982 12±3 mmHg; p<0.05), whereas PF-04418948 (10μg) had no effect. We conclude that spinal COX-1, but not COX-2, plays a role in evoking the exercise pressor reflex, and that the spinal prostaglandins produced by this enzyme are most likely activating spinal EP4 receptors, but not EP2 receptors. PMID:25003710

Role of cholinergic receptors in locomotion induced by scopolamine and oxotremorine-M.

PubMed

Chintoh, Araba; Fulton, James; Koziel, Nicole; Aziz, Mariam; Sud, Manu; Yeomans, John S

2003-08-01

Mesopontine cholinergic neurons activate dopamine neurons important for reward-seeking and locomotor activity. The present studies tested whether cholinergic receptor blockade in the ventral tegmental area (VTA) altered locomotion induced by scopolamine (3 mg/kg i.p.) or by oxotremorine-M (0.1 microg bilaterally in the VTA). It was predicted that cholinergic blockers in the VTA would attenuate these cholinergic-induced locomotor increases. Locomotor activity was increased by scopolamine and oxotremorine-M administration in all treatments. When dihydro-beta-erythroidine (DHBE), a nicotinic receptor antagonist, was applied in VTA prior to oxotremorine-M, locomotion was reduced to slightly above saline baseline levels, but atropine, a muscarinic antagonist, had no effect. This suggests that the locomotor effect of oxotremorine-M at this dose was mediated mainly via nicotinic, not muscarinic, receptors. Intra-VTA injections of DHBE, however, did not attenuate scopolamine-induced locomotion indicating that scopolamine-induced locomotion is not mediated mainly via VTA cholinergic receptors. In mutant mice with a deletion in the M5 muscarinic receptor gene, scopolamine-induced locomotion was increased versus wild type mice after scopolamine injection. This suggests that the M5 receptor has an inhibitory effect on scopolamine-induced locomotion.

Spontaneous firing and evoked responses of spinal nociceptive neurons are attenuated by blockade of P2X3 and P2X2/3 receptors in inflamed rats.

PubMed

Xu, Jun; Chu, Katharine L; Brederson, Jill-Desiree; Jarvis, Michael F; McGaraughty, Steve

2012-08-01

P2X3 and P2X2/3 receptors are selectively expressed on primary afferent nociceptors and have been implicated in modulating nociception in different models of pathological pain, including inflammatory pain. In an effort to delineate further the role of P2X3 receptors (homomeric and heteromeric) in the modulation of nociceptive transmission after a chronic inflammation injury, A-317491, a potent and selective P2X3-P2X2/3 antagonist, was administered to CFA-inflamed rats in order to examine its effects on responses of spinal dorsal horn neurons to mechanical and thermal stimulation. Systemic injection of A-317491 (30 μmol/kg, i.v.) reduced the responses of wide-dynamic-range (WDR) and nociceptive specific (NS) neurons to both high-intensity mechanical (pinch) and heat (49°C) stimulation. A-317491 also decreased low-intensity (10 g von Frey hair) mechanically evoked activity of WDR neurons but did not alter WDR neuronal responses to cold stimulation (5°C). Spontaneous firing of WDR neurons in CFA-inflamed rats was also significantly attenuated by A-317491 injection. By using immunohistochemistry, P2X3 receptors were demonstrated to be enhanced in lamina II of the spinal dorsal horn after inflammation. In summary, blockade of P2X3 and P2X2/3 receptors dampens mechanical- and heat-related signaling, as well as nonevoked activity of key classes of spinal nociceptive neurons in inflamed animals. These data suggest that P2X3 and/or P2X2/3 receptors have a broad contribution to somatosensory/nociceptive transmission in rats with a chronic inflammatory injury and are consistent with previous behavioral data demonstrating antiallodynic and antihyperalgesic effects of receptor antagonists. Copyright © 2012 Wiley Periodicals, Inc.

Muscarinic Receptor Activation Protects Cells from Apoptotic Effects of DNA Damage, Oxidative Stress, and Mitochondrial Inhibition*

PubMed Central

De Sarno, Patrizia; Shestopal, Svetlana A.; King, Taj D.; Zmijewska, Anna; Song, Ling; Jope, Richard S.

2006-01-01

The impact of muscarinic receptor stimulation was examined on apoptotic signaling induced by DNA damage, oxidative stress, and mitochondrial impairment. Exposure of human neuroblastoma SH-SY5Y cells to the DNA-damaging agent camptothecin increased p53 levels, activated caspase-3, and caused cell death. Pretreatment with oxotremorine-M, a selective agonist of muscarinic receptors that are expressed endogenously in these cells, did not affect the accumulation of p53 but greatly attenuated caspase-3 activation and protected from cell death to nearly the same extent as treatment with a general caspase inhibitor. Treatment with 50–200 μm H2O2 caused the activation of caspase-3 beginning after 2–3 h, followed by eventual cell death. Oxotremorine-M pretreatment protected cells from H2O2-inducedcaspase-3 activation and death, and this was equivalent to protection afforded by a caspase inhibitor. Muscarinic receptor stimulation also protected cells from caspase-3 activation induced by exposure to rotenone, a mitochondrial complex 1 inhibitor, but no protection was evident from staurosporine-induced caspase-3 activation. The mechanism of protection afforded by muscarinic receptor activation from camptothecin-induced apoptotic signaling involved blockade of mitochondrial cytochrome c release associated with a bolstering of mitochondrial bcl-2 levels and blockade of the translocation of Bax to mitochondria. Likely the most proximal of these events to muscarinic receptor activation, mitochondrial Bax accumulation, also was attenuated by oxotremorine-M treatment after treatment with H2O2 or rotenone. These results demonstrate that stimulation of muscarinic receptors provides substantial protection from DNA damage, oxidative stress, and mitochondrial impairment, insults that may be encountered by neurons in development, aging, or neurodegenerative diseases. These findings suggest that neurotransmitter-induced signaling bolsters survival mechanisms, and inadequate neurotransmission may exacerbate neuronal loss. PMID:12538580

Role of ATP-sensitive potassium channels in the piracetam induced blockade of opioid effects.

PubMed

Rehni, Ashish K; Singh, Nirmal; Jindal, Seema

2007-12-01

The present study has been designed to investigate the effect of piracetam on morphine/ buprenorphine-induced antinociception in rats and effect of piracetam on morphine or minoxidil induced relaxation in KCl-precontracted isolated rat aortic ring preparation. Nociceptive threshold was measured by the tail flick test in rats. The cumulative dose responses of morphine or minoxidil were recorded in KCl-precontracted isolated rat aortic ring preparation. Piracetam attenuated buprenorphine-induced antinociception in rats. Piracetam significantly reduced the morphine and minoxidil induced relaxation in KCl precontracted isolated rat aortic ring preparation suggesting that piracetam interferes with opioid receptor and ATP-sensitive potassium channel (KATP) opener mediated responses in vitro. Thus, it may be suggested that piracetam attenuates opioid effects by an opioid receptor-KATP channel linked mechanism.

CB1 cannabinoid receptor-mediated anandamide signalling reduces the defensive behaviour evoked through GABAA receptor blockade in the dorsomedial division of the ventromedial hypothalamus.

PubMed

Dos Anjos-Garcia, Tayllon; Ullah, Farhad; Falconi-Sobrinho, Luiz Luciano; Coimbra, Norberto Cysne

2017-02-01

The effects of cannabinoids in brain areas expressing cannabinoid receptors, such as hypothalamic nuclei, are not yet well known. Several studies have demonstrated the role of hypothalamic nuclei in the organisation of behavioural responses induced through innate fear and panic attacks. Panic-prone states are experimentally induced in laboratory animals through a reduction in the GABAergic activity. The aim of the present study was to examine panic-like elaborated defensive behaviour evoked by GABA A receptor blockade with bicuculline (BIC) in the dorsomedial division of the ventromedial hypothalamus (VMHdm). We also aimed to characterise the involvement of endocannabinoids and the CB 1 cannabinoid receptor in the modulation of elaborated defence behavioural responses organised with the VMHdm. The guide-cannula was stereotaxicaly implanted in VMHdm and the animals were treated with anandamide (AEA) at different doses, and the effective dose was used after the pre-treatment with the CB 1 receptor antagonist AM251, followed by GABA A receptor blockade in VMHdm. The results showed that the intra-hypothalamic administration of AEA at an intermediate dose (5 pmol) attenuated defence responses induced through the intra-VMHdm microinjection of bicuculline (40 ng). This effect, however, was inhibited when applied central microinjection of the CB 1 receptor antagonist AM251 in the VMHdm. Moreover, AM251 potentiates de non-oriented escape induced by bicuculline, effect blocked by pre-treatment with the TRPV 1 channel antagonist 6-I-CPS. These results indicate that AEA modulates the pro-aversive effects of intra-VMHdm-bicuculline treatment, recruiting CB 1 cannabinoid receptors and the TRPV1 channel is involved in the AM251-related potentiation of bicuculline effects on non-oriented escape behaviour. Copyright © 2016 Elsevier Ltd. All rights reserved.

Combination Direct Renin Inhibition with Angiotensin Type 1 Receptor Blockade improves Aldosterone but does not improve Kidney Injury in the Transgenic Ren2 rat

PubMed Central

Whaley-Connell, Adam; Habibi, Javad; Nistala, Ravi; Hayden, Melvin R; Pulakat, Lakshmi; Sinak, Catherine; Locher, Bonnie; Ferrario, Carlos M; Sowers, James R

2012-01-01

Enhanced renin-angiotensin-aldosterone system (RAAS) activation contributes to proteinuria and chronic kidney disease by increasing glomerular and tubulointerstitial oxidative stress, promotion of fibrosis. Renin activation is the rate limiting step in angiotensin (Ang II) and aldosterone generation, and recent work suggests direct renin inhibition improves proteinuria comparable to that seen with Ang type 1 receptor (AT1R) blockade. This is important as, even with contemporary use of AT1R blockade, the burden of kidney disease remains high. Thereby, we sought to determine if combination direct renin inhibition with AT1R blockade in vivo, via greater attenuation of kidney oxidative stress, would attenuate glomerular and proximal tubule injury to a greater extent than either intervention alone. We utilized the transgenic Ren2 rat with increased tissue RAS activity and higher serum levels of aldosterone, which manifests hypertension and proteinuria. Ren2 rats were treated with renin inhibition (aliskiren), AT1R blockade (valsartan), the combination (aliskiren+valsartan), or vehicle for 21 days. Compared to Sprague-Dawley controls, Ren2 rats displayed increased systolic pressure (SBP), circulating aldosterone, proteinuria and greater urine levels of the proximal tubule protein excretory marker beta-N-acetylglucosaminidase (β-NAG). These functional and biochemical alterations were accompanied by increases in kidney tissue NADPH oxidase subunit Rac1 and 3-nitrotyrosine (3-NT) content as well as fibronectin and collagen type III. These findings occurred in conjunction with reductions in the podocyte-specific protein podocin as well as the proximal tubule-specific megalin. Further, in transgenic animals there was increased tubulointerstitial fibrosis on light microscopy as well as ultrastructural findings of glomerular podocyte foot-process effacement and reduced tubular apical endosomal/lysosomal activity. Combination therapy led to greater reductions in SBP and serum aldosterone, but did not result in greater improvement in markers of glomerular and tubular injury (ie. β-NAG) compared to either intervention alone. Further, combination therapy did not improve markers of oxidative stress and podocyte and proximal tubule integrity in this transgenic model of RAAS-mediated kidney damage despite greater reductions in serum aldosterone and BP levels. PMID:22465166

Blockade of central nicotine acetylcholine receptor signaling attenuate ghrelin-induced food intake in rodents.

PubMed

Dickson, S L; Hrabovszky, E; Hansson, C; Jerlhag, E; Alvarez-Crespo, M; Skibicka, K P; Molnar, C S; Liposits, Z; Engel, J A; Egecioglu, E

2010-12-29

Here we sought to determine whether ghrelin's central effects on food intake can be interrupted by nicotine acetylcholine receptor (nAChR) blockade. Ghrelin regulates mesolimbic dopamine neurons projecting from the ventral tegmental area (VTA) to the nucleus accumbens, partly via cholinergic VTA afferents originating in the laterodorsal tegmental area (LDTg). Given that these cholinergic projections to the VTA have been implicated in natural as well as drug-induced reinforcement, we sought to investigate the role of cholinergic signaling in ghrelin-induced food intake as well as fasting-induced food intake, for which endogenous ghrelin has been implicated. We found that i.p. treatment with the non-selective centrally active nAChR antagonist, mecamylamine decreased fasting-induced food intake in both mice and rats. Moreover, central administration of mecamylamine decreased fasting-induced food intake in rats. I.c.v. ghrelin-induced food intake was suppressed by mecamylamine i.p. but not by hexamethonium i.p., a peripheral nAChR antagonist. Furthermore, mecamylamine i.p. blocked food intake following ghrelin injection into the VTA. Expression of the ghrelin receptor, the growth hormone secretagogue receptor 1A, was found to co-localize with choline acetyltransferase, a marker of cholinergic neurons, in the LDTg. Finally, mecamylamine treatment i.p. decreased the ability of palatable food to condition a place preference. These data suggest that ghrelin-induced food intake is partly mediated via nAChRs and that nicotinic blockade decreases the rewarding properties of food. Copyright © 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

Potentiation of Brain Stimulation Reward by Morphine: Effects of Neurokinin-1 Receptor Antagonism

PubMed Central

Robinson, J.E.; Fish, E.W.; Krouse, M.C.; Thorsell, A.; Heilig, M.; Malanga, C.J.

2012-01-01

Rationale The abuse potential of opioids may be due to their reinforcing and rewarding effects, which may be attenuated by neurokinin-1 receptor (NK1R) antagonists. Objective To measure the effects of opioid and neurokinin-1 (NK1R) receptor blockade on the potentiation of brain stimulation reward (BSR) by morphine using the intracranial self-stimulation (ICSS) method. Methods Adult male C57BL/6J mice (n = 15) were implanted with unipolar stimulating electrodes in the lateral hypothalamus and trained to respond for varying frequencies of rewarding electrical stimulation. The BSR threshold (θ0) and maximum response rate (MAX) were determined before and after intraperitoneal administration of saline, morphine (1.0 - 17.0 mg/kg), or the NK1R antagonists L-733,060 (1.0 - 17.0 mg/kg) and L-703,606 (1.0 - 17.0 mg/kg). In morphine antagonism experiments, naltrexone (0.1 – 1.0 mg/kg) or 10.0 mg/kg L-733,060 or L-703,606 was administered 15 minutes before morphine (1.0 - 10.0 mg/kg) or saline. Results Morphine dose-dependently decreased θ0 (maximum effect = 62% of baseline) and altered MAX when compared to saline. L-703,606 and L-733,060 altered θ0 without affecting MAX. 10.0 mg/kg L-733,060 and L-703,606, which did not affect θ0 or MAX, attenuated the effects of 3.0 and 10.0 mg/kg morphine. 1.0 and 0.3 mg/kg naltrexone blocked the effects of 10.0 mg/kg morphine. Naltrexone given before saline did not affect θ0 or MAX. Conclusions The decrease in θ0 by morphine reflects its rewarding effects, which were attenuated by NK1R and opioid receptor blockade. These results demonstrate the importance of substance P signaling during limbic reward system activation by opioids. PMID:21909635

The Roles of Dopamine D2 Receptor in the Social Hierarchy of Rodents and Primates.

PubMed

Yamaguchi, Yoshie; Lee, Young-A; Kato, Akemi; Jas, Emanuel; Goto, Yukiori

2017-02-24

Dopamine (DA) plays significant roles in regulation of social behavior. In social groups of humans and other animals, social hierarchy exists, which is determined by several behavioral characteristics such as aggression and impulsivity as well as social affiliations. In this study, we investigated the effects of pharmacological blockade of DA D2 receptor on social hierarchy of Japanese macaque and mouse social groups. We found acute administration of the D2 antagonist, sulpiride, in socially housed Japanese macaques attenuated social dominance when the drug was given to high social class macaques. A similar attenuation of social dominance was observed in high social class mice with D2 antagonist administration. In contrast, D2 antagonist administration in low social class macaque resulted in more stable social hierarchy of the group, whereas such effect was not observed in mouse social group. These results suggest that D2 receptor signaling may play important roles in establishment and maintenance of social hierarchy in social groups of several species of animals.

The Roles of Dopamine D2 Receptor in the Social Hierarchy of Rodents and Primates

PubMed Central

Yamaguchi, Yoshie; Lee, Young-A.; Kato, Akemi; Jas, Emanuel; Goto, Yukiori

2017-01-01

Dopamine (DA) plays significant roles in regulation of social behavior. In social groups of humans and other animals, social hierarchy exists, which is determined by several behavioral characteristics such as aggression and impulsivity as well as social affiliations. In this study, we investigated the effects of pharmacological blockade of DA D2 receptor on social hierarchy of Japanese macaque and mouse social groups. We found acute administration of the D2 antagonist, sulpiride, in socially housed Japanese macaques attenuated social dominance when the drug was given to high social class macaques. A similar attenuation of social dominance was observed in high social class mice with D2 antagonist administration. In contrast, D2 antagonist administration in low social class macaque resulted in more stable social hierarchy of the group, whereas such effect was not observed in mouse social group. These results suggest that D2 receptor signaling may play important roles in establishment and maintenance of social hierarchy in social groups of several species of animals. PMID:28233850

Haloperidol-stomach lesions attenuation by pentadecapeptide BPC 157, omeprazole, bromocriptine, but not atropine, lansoprazole, pantoprazole, ranitidine, cimetidine and misoprostol in mice.

PubMed

Bilic, I; Zoricic, I; Anic, T; Separovic, J; Stancic-Rokotov, D; Mikus, D; Buljat, G; Ivankovic, D; Aralica, G; Prkacin, I; Perovic, D; Mise, S; Rotkvic, I; Petek, M; Rucman, R; Seiwerth, S; Sikiric, P

2001-03-09

The focus was on haloperidol (central dopamine antagonist)-stomach lesion, a longly described suitable counterpart of dopamine blocker cysteamine-duodenal lesion. In this, the contribution of blockade of central/peripheral dopamine receptors and prostaglandins synthesis, along with influence of antiulcer agents was evaluated in mice. Male NMRI Hannnover mice were sacrificed 24 h after haloperidol (25 mg/kg b.w. i.p., given alone or with saline (haloperidol+saline) (i) or in combination (ii,iii)). Supporting central dopamine predominance for haloperidol stomach lesion induction, co-administration of peripheral dopamine receptor antagonist domperidone (5 mg/kg i.p.) (haloperidol+ domperidone) (ii), or prostaglandin synthesis inhibitor indomethacin (10 mg/kg s.c.) (haloperidol+ indomethacin) (iii) did not aggravate this lesion. (i) In haloperidol+saline challenged mice the lesions were inhibited by co-administration (/kg i.p.) of a gastric pentadecapeptide BPC 157, GlyGluProProProGlyLysProAlaAspAspAlaGlyLeuVal, M.W. 1419 (10 microg, 10 ng, 10 pg, but not 1 pg, 100 fg, 10 fg), bromocriptine (10 mg), omeprazole (10 mg, 100 mg, but not 1 mg). Atropine (10, 100, 200 mg), pirenzepine (10, 100, 200 mg), misoprostol (10, 100, 200 microg), pantoprazole (1, 10, 100 mg), lansoprazole (0.1, 1, 10 mg), cimetidine (10, 100, 200 mg) and ranitidine (10, 100, 200 mg) were not effective. (ii) Dopamine peripheral blockade influence: in haloperidol+domperidone mice, previously effective bromocriptine, pentadecapeptide BPC 157 (10 microg) or omeprazole (10 mg) did not attenuate stomach lesions. (iii) Prostaglandins synthesis blockade effect: in haloperidol+indomethacin mice, previously effective agents, bromocriptine or omeprazole were not active, while BPC 157 effect was only lessened.

Synaptically released zinc triggers metabotropic signaling via a zinc-sensing receptor in the hippocampus.

PubMed

Besser, Limor; Chorin, Ehud; Sekler, Israel; Silverman, William F; Atkin, Stan; Russell, James T; Hershfinkel, Michal

2009-03-04

Zn(2+) is coreleased with glutamate from mossy fiber terminals and can influence synaptic function. Here, we demonstrate that synaptically released Zn(2+) activates a selective postsynaptic Zn(2+)-sensing receptor (ZnR) in the CA3 region of the hippocampus. ZnR activation induced intracellular release of Ca(2+), as well as phosphorylation of extracellular-regulated kinase and Ca(2+)/calmodulin kinase II. Blockade of synaptic transmission by tetrodotoxin or CdCl inhibited the ZnR-mediated Ca(2+) rises. The responses mediated by ZnR were largely attenuated by the extracellular Zn(2+) chelator, CaEDTA, and in slices from mice lacking vesicular Zn(2+), suggesting that synaptically released Zn(2+) triggers the metabotropic activity. Knockdown of the expression of the orphan G-protein-coupled receptor 39 (GPR39) attenuated ZnR activity in a neuronal cell line. Importantly, we observed widespread GPR39 labeling in CA3 neurons, suggesting a role for this receptor in mediating ZnR signaling in the hippocampus. Our results describe a unique role for synaptic Zn(2+) acting as the physiological ligand of a metabotropic receptor and provide a novel pathway by which synaptic Zn(2+) can regulate neuronal function.

Angiotensin II type 1 receptor blockade by telmisartan prevents stress-induced impairment of memory via HPA axis deactivation and up-regulation of brain-derived neurotrophic factor gene expression.

PubMed

Wincewicz, D; Juchniewicz, A; Waszkiewicz, N; Braszko, J J

2016-09-01

Physical and psychological aspects of chronic stress continue to be a persistent clinical problem for which new pharmacological treatment strategies are aggressively sought. By the results of our previous work it has been demonstrated that telmisartan (TLM), an angiotensin type 1 receptor (AT1) blocker (ARB) and partial agonist of peroxisome proliferator-activated receptor gamma (PPARγ), alleviates stress-induced cognitive decline. Understanding of mechanistic background of this phenomenon is hampered by both dual binding sites of TLM and limited data on the consequences of central AT1 blockade and PPARγ activation. Therefore, a critical need exists for progress in the characterization of this target for pro-cognitive drug discovery. An unusual ability of novel ARBs to exert various PPARγ binding activities is commonly being viewed as predominant over angiotensin blockade in terms of neuroprotection. Here we aimed to verify this hypothesis using an animal model of chronic psychological stress (Wistar rats restrained 2.5h daily for 21days) with simultaneous oral administration of TLM (1mg/kg), GW9662 - PPARγ receptor antagonist (0.5mg/kg), or both in combination, followed by a battery of behavioral tests (open field, elevated plus maze, inhibitory avoidance - IA, object recognition - OR), quantitative determination of serum corticosterone (CORT) and evaluation of brain-derived neurotrophic factor (BDNF) gene expression in the medial prefrontal cortex (mPFC) and hippocampus (HIP). Stressed animals displayed decreased recall of the IA behavior (p<0.001), decreased OR (p<0.001), substantial CORT increase (p<0.001) and significantly downregulated expression of BDNF in the mPFC (p<0.001), which were attenuated in rats receiving TLM and TLM+GW9662. These data indicate that procognitive effect of ARBs in stressed subjects do not result from PPAR-γ activation, but AT1 blockade and subsequent hypothalamus-pituitary-adrenal axis deactivation associated with changes in primarily cortical gene expression. This study confirms the dual activities of TLM that controls hypertension and cognition through AT1 blockade. Copyright © 2016 Elsevier Inc. All rights reserved.

Myeloid mineralocorticoid receptor deficiency inhibits aortic constriction-induced cardiac hypertrophy in mice.

PubMed

Li, Chao; Zhang, Yu Yao; Frieler, Ryan A; Zheng, Xiao Jun; Zhang, Wu Chang; Sun, Xue Nan; Yang, Qing Zhen; Ma, Shu Min; Huang, Baozhuan; Berger, Stefan; Wang, Wang; Wu, Yong; Yu, Ying; Duan, Sheng Zhong; Mortensen, Richard M

2014-01-01

Mineralocorticoid receptor (MR) blockade has been shown to suppress cardiac hypertrophy and remodeling in animal models of pressure overload (POL). This study aims to determine whether MR deficiency in myeloid cells modulates aortic constriction-induced cardiovascular injuries. Myeloid MR knockout (MMRKO) mice and littermate control mice were subjected to abdominal aortic constriction (AAC) or sham operation. We found that AAC-induced cardiac hypertrophy and fibrosis were significantly attenuated in MMRKO mice. Expression of genes important in generating reactive oxygen species was decreased in MMRKO mice, while that of manganese superoxide dismutase increased. Furthermore, expression of genes important in cardiac metabolism was increased in MMRKO hearts. Macrophage infiltration in the heart was inhibited and expression of inflammatory genes was decreased in MMRKO mice. In addition, aortic fibrosis and inflammation were attenuated in MMRKO mice. Taken together, our data indicated that MR deficiency in myeloid cells effectively attenuated aortic constriction-induced cardiac hypertrophy and fibrosis, as well as aortic fibrosis and inflammation.

Endogenous opioid system: a promising target for future smoking cessation medications.

PubMed

Norman, Haval; D'Souza, Manoranjan S

2017-05-01

Nicotine addiction continues to be a health challenge across the world. Despite several approved medications, smokers continue to relapse. Several human and animal studies have evaluated the role of the endogenous opioid system as a potential target for smoking cessation medications. In this review, studies that have elucidated the role of the mu (MORs), delta (DORs), and kappa (KORs) opioid receptors in nicotine reward, nicotine withdrawal, and reinstatement of nicotine seeking will be discussed. Additionally, the review will discuss discrepancies in the literature and therapeutic potential of the endogenous opioid system, and suggest studies to address gaps in knowledge with respect to the role of the opioid receptors in nicotine dependence. Data available till date suggest that blockade of the MORs and DORs decreased the rewarding effects of nicotine, while activation of the MORs and DORs decreased nicotine withdrawal-induced aversive effects. In contrast, activation of the KORs decreased the rewarding effects of nicotine, while blockade of the KORs decreased nicotine withdrawal-induced aversive effects. Interestingly, blockade of the MORs and KORs attenuated reinstatement of nicotine seeking. In humans, MOR antagonists have shown benefits in select subpopulations of smokers and further investigation is required to realize their full therapeutic potential. Future work must assess the influence of polymorphisms in opioid receptor-linked genes in nicotine dependence, which will help in both identifying individuals vulnerable to nicotine addiction and the development of opioid-based smoking cessation medications. Overall, the endogenous opioid system continues to be a promising target for future smoking cessation medications.

Methamphetamine induces striatal neurokinin-1 receptor endocytosis primarily in somatostatin/NPY/NOS interneurons and the role of dopamine receptors in mice.

PubMed

Wang, Jing; Angulo, Jesus A

2011-04-01

Methamphetamine (METH) is a psychostimulant that induces long-term deficits of dopamine terminal markers and apoptotic cell death in the striatum. Our laboratory demonstrated that pharmacological blockade of the neurokinin-1 receptor attenuated the METH-induced damage to the striatal dopamine terminals and the apoptotic cell death of some striatal neurons. Here, we used histological methods to assess the effect of METH on neurokinin-1 receptor trafficking in the striatum as an indirect index of signaling by the neuropeptide substance P (natural ligand for this receptor). Male mice received a single injection of METH (30 mg/kg, i.p.) and were sacrificed 30 min later. Immunohistofluorescence confocal microscopy confirmed that the neurokinin-1 receptor is located on cholinergic and somatostatin interneurons of the striatum. METH induced the trafficking of the neurokinin-1 receptor from the membrane into cytoplasmic endosomes primarily in the somatostatin/NPY/NOS interneurons, and this phenomenon was attenuated by antagonists of the dopamine D1 (SCH-23390), D2 (raclopride), or neurokinin-1 (WIN-51,708) receptors. These data demonstrate that METH induces the trafficking of the striatal neurokinin-1 receptors principally in the somatostatin/NPY/NOS interneurons and that this phenomenon is dependent on the activity of dopamine D1 and D2 receptors. Copyright © 2010 Wiley-Liss, Inc.

The role of AT1-receptor blockade on reactive oxygen species and cardiac autonomic drive in experimental hyperthyroidism.

PubMed

Baraldi, D; Casali, K; Fernandes, R O; Campos, C; Sartório, C; Conzatti, A; Couto, G K; Schenkel, P C; Belló-Klein, A; Araujo, A R S

2013-10-01

The objective of this study was to explore the influence of the renin-angiotensin system on cardiac prooxidants and antioxidants levels and its association to autonomic imbalance induced by hyperthyroidism. Male Wistar rats were divided into four groups: control, losartan (10mg/kg/day by gavage, 28 day), thyroxine (T4) (12 mg/L in drinking water for 28 days), and T4+losartan. Spectral analysis (autonomic balance), angiotensin II receptor (AT1R), NADPH oxidase, Nrf2 and heme-oxygenase-1 (HO-1) myocardial protein expression, and hydrogen peroxide (H2O2) concentration were quantified. Autonomic imbalance induced by hyperthyroidism (~770%) was attenuated in the T4+losartan group (~32%) (P<0.05). AT1R, NADPH oxidase, H2O2, as well as concentration, Nrf2 and HO-1 protein expression were elevated (~172%, 43%, 40%, 133%, and 154%, respectively) in T4 group (P<0.05). H2O2 and HO-1 levels were returned to control values in the T4+losartan group (P<0.05). The overall results demonstrate a positive impact of RAS blockade in the autonomic control of heart rate, which was associated with an attenuation of H2O2 levels, as well as with a reduced counter-regulatory response of HO-1 in experimental hyperthyroidism. Copyright © 2013 Elsevier B.V. All rights reserved.

Role of Mas receptor in renal blood flow response to angiotensin (1-7) in male and female rats.

PubMed

Nematbakhsh, Mehdi; Safari, Tahereh

2014-01-01

Epidemiologic and clinical studies have shown that progression of renal disease in male is faster than that in female. However, the exact mechanisms are not well recognized. Angiotensin (1-7) (Ang 1-7) receptor, called "Mas", is an element in the depressor arm of renin angiotensin system (RAS), and its expression is enhanced in females. We test the hypothesis that Mas receptor (MasR) blockade (A779) attenuates renal blood flow (RBF) in response to infusion of graded doses of Ang 1-7 in female rats. Male and female Wistar rats were anesthetized and catheterized. Then, the mean arterial pressure (MAP), RBF, and controlled renal perfusion pressure (RPP) responses to infusion of graded doses of Ang 1-7 (100-1000 ng/kg/min i.v.) with and without A779 were measured in the animals. Basal MAP, RPP, RBF, and renal vascular resistance (RVR) were not significantly different between the two groups. After Ang 1-7 administration, RPP was controlled at a constant level. However, RBF increased in a dose-related manner in response to Ang 1-7 infusion in both male and female rats (Pdose<0.0001), but masR blockade significantly attenuated this response only in female (Pgroup=0.04) and not male (Pgroup=0.23). In addition, A779 increased the RBF response to Ang 1-7 to a greater extent. This is while the increase in male was not significant when compared with that in female (Pgender=0.08). RVR response to Ang 1-7 was insignificantly attenuated by A779 in both genders. The masR differently regulated RBF response to Ang 1-7 in the two genders, and the effect was greater in female rats. The masR may be a target for improvement of kidney circulation in renal diseases.

Blockade and knock-out of CALHM1 channels attenuate ischemic brain damage.

PubMed

Cisneros-Mejorado, Abraham; Gottlieb, Miroslav; Ruiz, Asier; Chara, Juan C; Pérez-Samartín, Alberto; Marambaud, Philippe; Matute, Carlos

2018-06-01

Overactivation of purinergic receptors during cerebral ischemia results in a massive release of neurotransmitters, including adenosine triphosphate (ATP), to the extracellular space which leads to cell death. Some hypothetical pathways of ATP release are large ion channels, such as calcium homeostasis modulator 1 (CALHM1), a membrane ion channel that can permeate ATP. Since this transmitter contributes to postischemic brain damage, we hypothesized that CALHM1 activation may be a relevant target to attenuate stroke injury. Here, we analyzed the contribution of CALHM1 to postanoxic depolarization after ischemia in cultured neurons and in cortical slices. We observed that the onset of postanoxic currents in neurons in those preparations was delayed after its blockade with ruthenium red or silencing of Calhm1 gene by short hairpin RNA, as well as in slices from CALHM1 knockout mice. Subsequently, we used transient middle cerebral artery occlusion and found that ruthenium red, a blocker of CALHM1, or the lack of CALHM1, substantially attenuated the motor symptoms and reduced significantly the infarct volume. These results show that CALHM1 channels mediate postanoxic depolarization in neurons and brain damage after ischemia. Therefore, targeting CALHM1 may have a high therapeutic potential for treating brain damage after ischemia.

Selective endothelin ETA and dual ET(A)/ET(B) receptor blockade improve endothelium-dependent vasodilatation in patients with type 2 diabetes and coronary artery disease.

PubMed

Rafnsson, Arnar; Shemyakin, Alexey; Pernow, John

2014-11-24

Endothelin-1 contributes to endothelial dysfunction in patients with atherosclerosis and type 2 diabetes. In healthy arteries the ETA receptor mediates the main part of the vasoconstriction induced by endothelin-1 whilst the ETB receptor mediates vasodilatation. The ETB receptor expression is upregulated on vascular smooth muscle cells in atherosclerosis and may contribute to the increased vasoconstrictor tone and endothelial dysfunction observed in this condition. Due to these opposing effects of the ETB receptor it remains unclear whether ETB blockade together with ETA blockade may be detrimental or beneficial. The aim was therefore to compare the effects of selective ETA and dual ETA/ETB blockade on endothelial function in patients with type 2 diabetes and coronary artery disease. Forearm endothelium-dependent and endothelium-independent vasodilatation was assessed by venous occlusion plethysmography in 12 patients before and after selective ETA or dual ETA/ETB receptor blockade. Dual ETA/ETB receptor blockade increased baseline forearm blood flow by 30±14% (P<0.01) whereas selective ETA blockade did not (14±8%). Both selective ETA blockade and dual ETA/ETB blockade significantly improved endothelium-dependent vasodilatation. The improvement did not differ between the two treatments. There was also an increase in endothelium-independent vasodilatation with both treatments. Dual ETA/ETB blockade did not significantly increase microvascular flow but improved transcutaneous pO2. Both selective ETA and dual ETA/ETB improve endothelium-dependent vasodilatation in patients with type 2 diabetes and coronary artery disease. ETB blockade increases basal blood flow but does not additionally improve endothelium-dependent vasodilatation. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Activation of the sympathetic nervous system mediates hypophagic and anxiety-like effects of CB₁ receptor blockade.

PubMed

Bellocchio, Luigi; Soria-Gómez, Edgar; Quarta, Carmelo; Metna-Laurent, Mathilde; Cardinal, Pierre; Binder, Elke; Cannich, Astrid; Delamarre, Anna; Häring, Martin; Martín-Fontecha, Mar; Vega, David; Leste-Lasserre, Thierry; Bartsch, Dusan; Monory, Krisztina; Lutz, Beat; Chaouloff, Francis; Pagotto, Uberto; Guzman, Manuel; Cota, Daniela; Marsicano, Giovanni

2013-03-19

Complex interactions between periphery and the brain regulate food intake in mammals. Cannabinoid type-1 (CB1) receptor antagonists are potent hypophagic agents, but the sites where this acute action is exerted and the underlying mechanisms are not fully elucidated. To dissect the mechanisms underlying the hypophagic effect of CB1 receptor blockade, we combined the acute injection of the CB1 receptor antagonist rimonabant with the use of conditional CB1-knockout mice, as well as with pharmacological modulation of different central and peripheral circuits. Fasting/refeeding experiments revealed that CB1 receptor signaling in many specific brain neurons is dispensable for the acute hypophagic effects of rimonabant. CB1 receptor antagonist-induced hypophagia was fully abolished by peripheral blockade of β-adrenergic transmission, suggesting that this effect is mediated by increased activity of the sympathetic nervous system. Consistently, we found that rimonabant increases gastrointestinal metabolism via increased peripheral β-adrenergic receptor signaling in peripheral organs, including the gastrointestinal tract. Blockade of both visceral afferents and glutamatergic transmission in the nucleus tractus solitarii abolished rimonabant-induced hypophagia. Importantly, these mechanisms were specifically triggered by lipid-deprivation, revealing a nutrient-specific component acutely regulated by CB1 receptor blockade. Finally, peripheral blockade of sympathetic neurotransmission also blunted central effects of CB1 receptor blockade, such as fear responses and anxiety-like behaviors. These data demonstrate that, independently of their site of origin, important effects of CB1 receptor blockade are expressed via activation of peripheral sympathetic activity. Thus, CB1 receptors modulate bidirectional circuits between the periphery and the brain to regulate feeding and other behaviors.

Activation of the sympathetic nervous system mediates hypophagic and anxiety-like effects of CB1 receptor blockade

PubMed Central

Bellocchio, Luigi; Soria-Gómez, Edgar; Quarta, Carmelo; Metna-Laurent, Mathilde; Cardinal, Pierre; Binder, Elke; Cannich, Astrid; Delamarre, Anna; Häring, Martin; Martín-Fontecha, Mar; Vega, David; Leste-Lasserre, Thierry; Bartsch, Dusan; Monory, Krisztina; Lutz, Beat; Chaouloff, Francis; Pagotto, Uberto; Guzman, Manuel; Cota, Daniela; Marsicano, Giovanni

2013-01-01

Complex interactions between periphery and the brain regulate food intake in mammals. Cannabinoid type-1 (CB1) receptor antagonists are potent hypophagic agents, but the sites where this acute action is exerted and the underlying mechanisms are not fully elucidated. To dissect the mechanisms underlying the hypophagic effect of CB1 receptor blockade, we combined the acute injection of the CB1 receptor antagonist rimonabant with the use of conditional CB1-knockout mice, as well as with pharmacological modulation of different central and peripheral circuits. Fasting/refeeding experiments revealed that CB1 receptor signaling in many specific brain neurons is dispensable for the acute hypophagic effects of rimonabant. CB1 receptor antagonist-induced hypophagia was fully abolished by peripheral blockade of β-adrenergic transmission, suggesting that this effect is mediated by increased activity of the sympathetic nervous system. Consistently, we found that rimonabant increases gastrointestinal metabolism via increased peripheral β-adrenergic receptor signaling in peripheral organs, including the gastrointestinal tract. Blockade of both visceral afferents and glutamatergic transmission in the nucleus tractus solitarii abolished rimonabant-induced hypophagia. Importantly, these mechanisms were specifically triggered by lipid-deprivation, revealing a nutrient-specific component acutely regulated by CB1 receptor blockade. Finally, peripheral blockade of sympathetic neurotransmission also blunted central effects of CB1 receptor blockade, such as fear responses and anxiety-like behaviors. These data demonstrate that, independently of their site of origin, important effects of CB1 receptor blockade are expressed via activation of peripheral sympathetic activity. Thus, CB1 receptors modulate bidirectional circuits between the periphery and the brain to regulate feeding and other behaviors. PMID:23487769

Chronic 5-HT2 receptor blockade unmasks the role of 5-HT1F receptors in the inhibition of rat cardioaccelerator sympathetic outflow.

PubMed

García-Pedraza, José Ángel; Hernández-Abreu, Oswaldo; García, Mónica; Morán, Asunción; Villalón, Carlos M

2018-04-01

Serotonin (5-hydroxytryptamine; 5-HT) inhibits the rat cardioaccelerator sympathetic outflow by 5-HT 1B/1D/5 receptors. Because chronic blockade of sympatho-excitatory 5-HT 2 receptors is beneficial in several cardiovascular pathologies, this study investigated whether sarpogrelate (a 5-HT 2 receptor antagonist) alters the pharmacological profile of the above sympatho-inhibition. Rats were pretreated for 2 weeks with sarpogrelate in drinking water (30 mg/kg per day; sarpogrelate-treated group) or equivalent volumes of drinking water (control group). Animals were pithed and prepared for spinal stimulation (C 7 -T 1 ) of the cardioaccelerator sympathetic outflow or for intravenous (i.v.) bolus injections of noradrenaline. Both procedures produced tachycardic responses remaining unaltered after saline. Continuous i.v. infusions of 5-HT induced a cardiac sympatho-inhibition that was mimicked by the 5-HT receptor agonists 5-carboxamidotryptamine (5-CT; 5-HT 1/5A ), CP 93,129 (5-HT 1B ), or PNU 142633 (5-HT 1D ), but not by indorenate (5-HT 1A ) in both groups; whereas LY344864 (5-HT 1F ) mimicked 5-HT only in sarpogrelate-treated rats. In sarpogrelate-treated animals, i.v. GR 127935 (310 μg/kg; 5-HT 1B/1D/1F receptor antagonist) attenuated 5-CT-induced sympatho-inhibition and abolished LY344864-induced sympatho-inhibition; while GR 127935 plus SB 699551 (1 mg/kg; 5-HT 5A receptor antagonist) abolished 5-CT-induced inhibition. These results confirm the cardiac sympatho-inhibitory role of 5-HT 1B , 5-HT 1D , and 5-HT 5A receptors in both groups; nevertheless, sarpogrelate treatment specifically unmasked a cardiac sympatho-inhibition mediated by 5-HT 1F receptors.

Pharmacological blockade or genetic deletion of substance P (NK(1)) receptors attenuates neonatal vocalisation in guinea-pigs and mice.

PubMed

Rupniak, N M; Carlson, E C; Harrison, T; Oates, B; Seward, E; Owen, S; de Felipe, C; Hunt, S; Wheeldon, A

2000-06-08

The regulation of stress-induced vocalisations by central NK(1) receptors was investigated using pharmacological antagonists in guinea-pigs, a species with human-like NK(1) receptors, and transgenic NK1R-/- mice. In guinea-pigs, i.c.v. infusion of the selective substance P agonist GR73632 (0.1 nmol) elicited a pronounced vocalisation response that was blocked enantioselectively by the NK(1) receptor antagonists CP-99,994 and L-733,060 (0.1-10 mg/kg). GR73632-induced vocalisations were also markedly attenuated by the antidepressant drugs imipramine and fluoxetine (30 mg/kg), but not by the benzodiazepine anxiolytic diazepam (3 mg/kg) or the 5-HT(1A) agonist buspirone (10 mg/kg). Similarly, vocalisations in guinea-pig pups separated from their mothers were blocked enantioselectively by the highly brain-penetrant NK(1) receptor antagonists L-733,060 and GR205171 (ID(50) 3 mg/kg), but not by the poorly brain-penetrant compounds LY303870 and CGP49823 (30 mg/kg). Separation-induced vocalisations were also blocked by the anxiolytic drugs diazepam, chlordiazepoxide and buspirone (ID(50) 0.5-1 mg/kg), and by the antidepressant drugs phenelzine, imipramine, fluoxetine and venlafaxine (ID(50) 3-8 mg/kg). In normal mouse pups, GR205171 attenuated neonatal vocalisations when administered at a high dose (30 mg/kg) only, consistent with its lower affinity for the rat than the guinea-pig NK(1) receptor. Ultrasound calls in NK1R-/- mouse pups were markedly reduced compared with those in WT pups, confirming the specific involvement of NK(1) receptors in the regulation of vocalisation. These observations suggest that centrally-acting NK(1) receptor antagonists may have clinical utility in the treatment of a range of anxiety and mood disorders.

Novel antipsychotic agents with 5-HT(1A) agonist properties: role of 5-HT(1A) receptor activation in attenuation of catalepsy induction in rats.

PubMed

Kleven, Mark S; Barret-Grévoz, Catherine; Bruins Slot, Liesbeth; Newman-Tancredi, Adrian

2005-08-01

Compounds possessing 5-HT(1A) agonist properties attenuate catalepsy induced by D(2) receptor blockade. Here we examined the role of 5-HT(1A) receptor agonism in the reduced cataleptogenic potential of several novel antipsychotic agents in the crossed leg position (CLP) and the bar catalepsy tests in rats. When administered alone, ziprasidone produced marked catalepsy, whereas aripiprazole, bifeprunox, SLV313, SSR181507 and sarizotan did not. However, when 5-HT(1A) receptors were blocked with the selective antagonist, WAY100635 (0.63 mg/kg, SC), robust cataleptogenic properties of SLV313, bifeprunox and sarizotan were unmasked and the catalepsy induced by ziprasidone was accentuated. In contrast, only modest catalepsy was induced by aripiprazole and SSR181507, even following a higher dose of WAY100635 (2.5 mg/kg). This suggests that these compounds possess other anti-cataleptic properties, such as partial agonism at dopamine D(2) receptors. The capacity to reverse neuroleptic-induced catalepsy was investigated in interaction studies with haloperidol (2.5 mg/kg, SC). Whereas ziprasidone and aripiprazole did not markedly reduce the effects of haloperidol, SLV313 and sarizotan attenuated CLP catalepsy. In contrast, SSR181507 and bifeprunox potently inhibited both CLP and bar catalepsy. Taken together, these data show that 5-HT(1A) receptor activation reduces the cataleptogenic potential of novel antipsychotic agents but indicate marked diversity in the contribution of 5-HT(1A) and/or other mechanisms to the profiles of the drugs.

Blockade of neurokinin-1 receptors in the ventral respiratory column does not affect breathing but alters neurochemical release

PubMed Central

Muere, Clarissa; Neumueller, Suzanne; Olesiak, Samantha; Miller, Justin; Hodges, Matthew R.; Pan, Lawrence

2015-01-01

Substance P (SP) and its receptor, neurokinin-1 (NK1R), have been shown to be excitatory modulators of respiratory frequency and to stabilize breathing regularity. Studies in anesthetized mice suggest that tonic activation of NK1Rs is particularly important when other excitatory inputs to the pre-Bötzinger complex in the ventral respiratory column (VRC) are attenuated. Consistent with these findings, muscarinic receptor blockade in the VRC of intact goats elicits an increase in breathing frequency associated with increases in SP and serotonin concentrations, suggesting an involvement of these substances in neuromodulator compensation. To gain insight on the contribution to breathing of endogenous SP and NK1R activation, and how NK1R modulates the release of other neurochemicals, we individually dialyzed antagonists to NK1R (133, 267, 500 μM Spantide; 3 mM RP67580) throughout the VRC of awake and sleeping goats. We found that NK1R blockade with either Spantide at any dose or RP67580 had no effect on breathing or regularity. Both antagonists significantly (P < 0.001) increased SP, while RP67580 also increased serotonin and glycine and decreased thyrotropin-releasing hormone concentrations in the dialysate. Taken together, these data support the concept of neuromodulator interdependence, and we believe that the loss of excitatory input from NK1Rs was locally compensated by changes in other neurochemicals. PMID:25635003

Blockade of neurokinin-1 receptors in the ventral respiratory column does not affect breathing but alters neurochemical release.

PubMed

Muere, Clarissa; Neumueller, Suzanne; Olesiak, Samantha; Miller, Justin; Hodges, Matthew R; Pan, Lawrence; Forster, Hubert V

2015-03-15

Substance P (SP) and its receptor, neurokinin-1 (NK1R), have been shown to be excitatory modulators of respiratory frequency and to stabilize breathing regularity. Studies in anesthetized mice suggest that tonic activation of NK1Rs is particularly important when other excitatory inputs to the pre-Bötzinger complex in the ventral respiratory column (VRC) are attenuated. Consistent with these findings, muscarinic receptor blockade in the VRC of intact goats elicits an increase in breathing frequency associated with increases in SP and serotonin concentrations, suggesting an involvement of these substances in neuromodulator compensation. To gain insight on the contribution to breathing of endogenous SP and NK1R activation, and how NK1R modulates the release of other neurochemicals, we individually dialyzed antagonists to NK1R (133, 267, 500 μM Spantide; 3 mM RP67580) throughout the VRC of awake and sleeping goats. We found that NK1R blockade with either Spantide at any dose or RP67580 had no effect on breathing or regularity. Both antagonists significantly (P < 0.001) increased SP, while RP67580 also increased serotonin and glycine and decreased thyrotropin-releasing hormone concentrations in the dialysate. Taken together, these data support the concept of neuromodulator interdependence, and we believe that the loss of excitatory input from NK1Rs was locally compensated by changes in other neurochemicals. Copyright © 2015 the American Physiological Society.

Effect of acute aerobic exercise and histamine receptor blockade on arterial stiffness in African Americans and Caucasians

PubMed Central

Ranadive, Sushant M.; Lane-Cordova, Abbi D.; Kappus, Rebecca M.; Behun, Michael A.; Cook, Marc D.; Woods, Jeffrey A.; Wilund, Kenneth R.; Baynard, Tracy; Fernhall, Bo

2017-01-01

African Americans (AA) exhibit exaggerated central blood pressure (BP) and arterial stiffness measured by pulse wave velocity (PWV) in response to an acute bout of maximal exercise compared with Caucasians (CA). However, whether potential racial differences exist in central BP, elastic, or muscular arterial distensibility after submaximal aerobic exercise remains unknown. Histamine receptor activation mediates sustained postexercise hyperemia in CA but the effect on arterial stiffness is unknown. This study sought to determine the effects of an acute bout of aerobic exercise on central BP and arterial stiffness and the role of histamine receptors, in AA and CA. Forty-nine (22 AA, 27 CA) young and healthy subjects completed the study. Subjects were randomly assigned to take either histamine receptor antagonist or control placebo. Central blood BP and arterial stiffness measurements were obtained at baseline, and at 30, 60, and 90 min after 45 min of moderate treadmill exercise. AA exhibited greater central diastolic BP, elevated brachial PWV, and local carotid arterial stiffness after an acute bout of submaximal exercise compared with CA, which may contribute to their higher risk of cardiovascular disease. Unexpectedly, histamine receptor blockade did not affect central BP or PWV in AA or CA after exercise, but it may play a role in mediating local carotid arterial stiffness. Furthermore, histamine may mediate postexercise carotid arterial dilation in CA but not in AA. These observations provide evidence that young and healthy AA exhibit an exaggerated hemodynamic response to exercise and attenuated vasodilator response compared with CA. NEW & NOTEWORTHY African Americans are at greater risk for developing cardiovascular disease than Caucasians. We are the first to show that young and healthy African Americans exhibit greater central blood pressure, elevated brachial stiffness, and local carotid arterial stiffness following an acute bout of submaximal exercise compared with Caucasians, which may contribute to their higher risk of cardiovascular disease. Furthermore, African Americans exhibit attenuated vasodilator response compared with Caucasians. PMID:27979988

Effect of acute aerobic exercise and histamine receptor blockade on arterial stiffness in African Americans and Caucasians.

PubMed

Yan, Huimin; Ranadive, Sushant M; Lane-Cordova, Abbi D; Kappus, Rebecca M; Behun, Michael A; Cook, Marc D; Woods, Jeffrey A; Wilund, Kenneth R; Baynard, Tracy; Halliwill, John R; Fernhall, Bo

2017-02-01

African Americans (AA) exhibit exaggerated central blood pressure (BP) and arterial stiffness measured by pulse wave velocity (PWV) in response to an acute bout of maximal exercise compared with Caucasians (CA). However, whether potential racial differences exist in central BP, elastic, or muscular arterial distensibility after submaximal aerobic exercise remains unknown. Histamine receptor activation mediates sustained postexercise hyperemia in CA but the effect on arterial stiffness is unknown. This study sought to determine the effects of an acute bout of aerobic exercise on central BP and arterial stiffness and the role of histamine receptors, in AA and CA. Forty-nine (22 AA, 27 CA) young and healthy subjects completed the study. Subjects were randomly assigned to take either histamine receptor antagonist or control placebo. Central blood BP and arterial stiffness measurements were obtained at baseline, and at 30, 60, and 90 min after 45 min of moderate treadmill exercise. AA exhibited greater central diastolic BP, elevated brachial PWV, and local carotid arterial stiffness after an acute bout of submaximal exercise compared with CA, which may contribute to their higher risk of cardiovascular disease. Unexpectedly, histamine receptor blockade did not affect central BP or PWV in AA or CA after exercise, but it may play a role in mediating local carotid arterial stiffness. Furthermore, histamine may mediate postexercise carotid arterial dilation in CA but not in AA. These observations provide evidence that young and healthy AA exhibit an exaggerated hemodynamic response to exercise and attenuated vasodilator response compared with CA. NEW & NOTEWORTHY African Americans are at greater risk for developing cardiovascular disease than Caucasians. We are the first to show that young and healthy African Americans exhibit greater central blood pressure, elevated brachial stiffness, and local carotid arterial stiffness following an acute bout of submaximal exercise compared with Caucasians, which may contribute to their higher risk of cardiovascular disease. Furthermore, African Americans exhibit attenuated vasodilator response compared with Caucasians. Copyright © 2017 the American Physiological Society.

RAGE is a key cellular target for Aβ-induced perturbation in Alzheimer's disease

PubMed Central

Yan, Shirley ShiDu; Chen, Doris; Yan, Shiqian; Guo, Lan; Chen, John Xi

2013-01-01

RAGE, a receptor for advanced glycation endproducts, is an immunoglobulin-like cell surface receptor that is often described as a pattern recognition receptor due to the structural heterogeneity of its ligand. RAGE is an important cellular cofactor for amyloid β-peptide (Aβ)-mediated cellular perturbation relevant to the pathogenesis of Alzheimer's disease (AD). The interaction of RAGE with Aβ in neurons, microglia, and vascular cells accelerates and amplifies deleterious effects on neuronal and synaptic function. RAGE-dependent signaling contributes to Aβ-mediated amyloid pathology and cognitive dysfunction observed in the AD mouse model. Blockade of RAGE significantly attenuates neuronal and synaptic injury. In this review, we summarize the role of RAGE in the pathogenesis of AD, specifically in Aβ-induced cellular perturbation. PMID:22202057

Combination of direct renin inhibition with angiotensin type 1 receptor blockade improves aldosterone but does not improve kidney injury in the transgenic Ren2 rat.

PubMed

Whaley-Connell, Adam; Habibi, Javad; Nistala, Ravi; Hayden, Melvin R; Pulakat, Lakshmi; Sinak, Catherine; Locher, Bonnie; Ferrario, Carlos M; Sowers, James R

2012-06-10

Enhanced renin-angiotensin-aldosterone system (RAAS) activation contributes to proteinuria and chronic kidney disease by increasing glomerular and tubulointerstitial oxidative stress, promotion of fibrosis. Renin activation is the rate limiting step in angiotensin (Ang II) and aldosterone generation, and recent work suggests direct renin inhibition improves proteinuria comparable to that seen with Ang type 1 receptor (AT(1)R) blockade. This is important as, even with contemporary use of AT(1)R blockade, the burden of kidney disease remains high. Thereby, we sought to determine if combination of direct renin inhibition with AT(1)R blockade in vivo, via greater attenuation of kidney oxidative stress, would attenuate glomerular and proximal tubule injury to a greater extent than either intervention alone. We utilized the transgenic Ren2 rat with increased tissue RAS activity and higher serum levels of aldosterone, which manifests hypertension and proteinuria. Ren2 rats were treated with renin inhibition (aliskiren), AT(1)R blockade (valsartan), the combination (aliskiren+valsartan), or vehicle for 21days. Compared to Sprague-Dawley controls, Ren2 rats displayed increased systolic pressure (SBP), circulating aldosterone, proteinuria and greater urine levels of the proximal tubule protein excretory marker beta-N-acetylglucosaminidase (β-NAG). These functional and biochemical alterations were accompanied by increases in kidney tissue NADPH oxidase subunit Rac1 and 3-nitrotyrosine (3-NT) content as well as fibronectin and collagen type III. These findings occurred in conjunction with reductions in the podocyte-specific protein podocin as well as the proximal tubule-specific megalin. Further, in transgenic animals there was increased tubulointerstitial fibrosis on light microscopy as well as ultrastructural findings of glomerular podocyte foot-process effacement and reduced tubular apical endosomal/lysosomal activity. Combination therapy led to greater reductions in SBP and serum aldosterone, but did not result in greater improvement in markers of glomerular and tubular injury (i.e. β-NAG) compared to either intervention alone. Further, combination therapy did not improve markers of oxidative stress and podocyte and proximal tubule integrity in this transgenic model of RAAS-mediated kidney damage despite greater reductions in serum aldosterone and BP levels. Published by Elsevier B.V.

Pro-tumorigenic effects of transforming growth factor beta 1 in canine osteosarcoma.

PubMed

Portela, R F; Fadl-Alla, B A; Pondenis, H C; Byrum, M L; Garrett, L D; Wycislo, K L; Borst, L B; Fan, T M

2014-01-01

Transforming growth factor beta 1 (TGFβ1) is a pleiotropic cytokine that contributes to reparative skeletal remodeling by inducing osteoblast proliferation, migration, and angiogenesis. Organic bone matrix is the largest bodily reservoir for latent TGFβ1, and active osteoblasts express cognate receptors for TGFβ1 (TGFβRI and TGFβRII). During malignant osteolysis, TGFβ1 is liberated from eroded bone matrix and promotes local progression of osteotropic solid tumors by its mitogenic and prosurvival activities. Canine osteosarcoma (OS) cells will possess TGFβ1 signaling machinery. Blockade of TGFβ1 signaling will attenuate pro-tumorigenic activities in OS cells. Naturally occurring primary OS samples will express cognate TGFβ1 receptors; and in dogs with OS, focal malignant osteolysis will contribute to circulating TGFβ1 concentrations. Thirty-three dogs with appendicular OS. Expression of TGFβ1 and its cognate receptors, as well as the biologic effects of TGFβ1 blockade, was characterized in OS cells. Ten spontaneous OS samples were characterized for TGFβRI/II expressions by immunohistochemistry. In 33 dogs with OS, plasma TGFβ1 concentrations were quantified and correlated with bone resorption. Canine OS cells secrete TGFβ1, express cognate receptors, and TGFβ1 signaling blockade decreases proliferation, migration, and vascular endothelial growth factor secretion. Naturally occurring OS samples abundantly and uniformly express TGFβRI/II, and in OS-bearing dogs, circulating TGFβ1 concentrations correlate with urine N-telopeptide excretion. Canine OS cells possess TGFβ1 signaling machinery, potentially allowing for the establishment of an autocrine and paracrine pro-tumorigenic signaling loop. As such, TGFβ1 inhibitors might impede localized OS progression in dogs. Copyright © 2014 by the American College of Veterinary Internal Medicine.

The Triterpenoid Betulin Protects against the Neuromuscular Effects of Bothrops jararacussu Snake Venom In Vivo

PubMed Central

Ferraz, Miriéle Cristina; de Oliveira, Jhones Luiz; de Oliveira Junior, Joel Reis; Cogo, José Carlos; dos Santos, Márcio Galdino; Franco, Luiz Madaleno; Puebla, Pilar; Ferraz, Helena Onishi; Ferraz, Humberto Gomes; da Rocha, Marisa Maria Teixeira; Hyslop, Stephen

2015-01-01

We confirmed the ability of the triterpenoid betulin to protect against neurotoxicity caused by Bothrops jararacussu snake venom in vitro in mouse isolated phrenic nerve-diaphragm (PND) preparations and examined its capability of in vivo protection using the rat external popliteal/sciatic nerve-tibialis anterior (EPSTA) preparation. Venom caused complete, irreversible blockade in PND (40 μg/mL), but only partial blockade (~30%) in EPSTA (3.6 mg/kg, i.m.) after 120 min. In PND, preincubation of venom with commercial bothropic antivenom (CBA) attenuated the venom-induced blockade, and, in EPSTA, CBA given i.v. 15 min after venom also attenuated the blockade (by ~70% in both preparations). Preincubation of venom with betulin (200 μg/mL) markedly attenuated the venom-induced blockade in PND; similarly, a single dose of betulin (20 mg, i.p., 15 min after venom) virtually abolished the venom-induced decrease in contractility. Plasma creatine kinase activity was significantly elevated 120 min after venom injection in the EPSTA but was attenuated by CBA and betulin. These results indicate that betulin given i.p. has a similar efficacy as CBA given i.v. in attenuating the neuromuscular effects of B. jararacussu venom in vivo and could be a useful complementary measure to antivenom therapy for treating snakebite. PMID:26633987

Uridine Adenosine Tetraphosphate-Induced Coronary Relaxation Is Blunted in Swine With Pressure Overload: A Role for Vasoconstrictor Prostanoids

PubMed Central

Zhou, Zhichao; Lankhuizen, Inge M.; van Beusekom, Heleen M.; Cheng, Caroline; Duncker, Dirk J.; Merkus, Daphne

2018-01-01

Plasma levels of the vasoactive substance uridine adenosine tetraphosphate (Up4A) are elevated in hypertensive patients and Up4A-induced vascular contraction is exacerbated in various arteries isolated from hypertensive animals, suggesting a potential role of Up4A in development of hypertension. We previously demonstrated that Up4A produced potent and partially endothelium-dependent relaxation in the porcine coronary microvasculature. Since pressure-overload is accompanied by structural abnormalities in the coronary microvasculature as well as by endothelial dysfunction, we hypothesized that pressure-overload blunts the coronary vasodilator response to Up4A, and that the involvement of purinergic receptors and endothelium-derived factors is altered. The effects of Up4A were investigated using wire-myography in isolated coronary small arteries from Sham-operated swine and swine with prolonged (8 weeks) pressure overload of the left ventricle induced by aortic banding (AoB). Expression of purinergic receptors and endothelium-derived factors was assessed in isolated coronary small arteries using real-time PCR. Up4A (10-9 to 10-5 M) failed to produce contraction in isolated coronary small arteries from either Sham or AoB swine, but produced relaxation in preconstricted arteries, which was significantly blunted in AoB compared to Sham. Blockade of purinergic P1, and P2 receptors attenuated Up4A-induced coronary relaxation more, while the effect of P2X1-blockade was similar and the effects of A2A- and P2Y1-blockade were reduced in AoB as compared to Sham. mRNA expression of neither A1, A2, A3, nor P2X1, P2X7, P2Y1, P2Y2, nor P2Y6-receptors was altered in AoB as compared to Sham, while P2Y12 expression was higher in AoB. eNOS inhibition attenuated Up4A-induced coronary relaxation in both Sham and AoB. Additional blockade of cyclooxygenase enhanced Up4A-induced coronary relaxation in AoB but not Sham swine, suggesting the involvement of vasoconstrictor prostanoids. In endothelium-denuded coronary small arteries from normal swine, thromboxane synthase (TxS) inhibition enhanced relaxation to Up4A compared to endothelium-intact arteries, to a similar extent as P2Y12 inhibition, while the combination inhibition of P2Y12 and TxS had no additional effect. In conclusion, Up4A-induced coronary relaxation is blunted in swine with AoB, which appears to be due to the production of a vasoconstrictor prostanoid, likely thromboxane A2. PMID:29632487

Uridine Adenosine Tetraphosphate-Induced Coronary Relaxation Is Blunted in Swine With Pressure Overload: A Role for Vasoconstrictor Prostanoids.

PubMed

Zhou, Zhichao; Lankhuizen, Inge M; van Beusekom, Heleen M; Cheng, Caroline; Duncker, Dirk J; Merkus, Daphne

2018-01-01

Plasma levels of the vasoactive substance uridine adenosine tetraphosphate (Up 4 A) are elevated in hypertensive patients and Up 4 A-induced vascular contraction is exacerbated in various arteries isolated from hypertensive animals, suggesting a potential role of Up 4 A in development of hypertension. We previously demonstrated that Up 4 A produced potent and partially endothelium-dependent relaxation in the porcine coronary microvasculature. Since pressure-overload is accompanied by structural abnormalities in the coronary microvasculature as well as by endothelial dysfunction, we hypothesized that pressure-overload blunts the coronary vasodilator response to Up 4 A, and that the involvement of purinergic receptors and endothelium-derived factors is altered. The effects of Up 4 A were investigated using wire-myography in isolated coronary small arteries from Sham-operated swine and swine with prolonged (8 weeks) pressure overload of the left ventricle induced by aortic banding (AoB). Expression of purinergic receptors and endothelium-derived factors was assessed in isolated coronary small arteries using real-time PCR. Up 4 A (10 -9 to 10 -5 M) failed to produce contraction in isolated coronary small arteries from either Sham or AoB swine, but produced relaxation in preconstricted arteries, which was significantly blunted in AoB compared to Sham. Blockade of purinergic P1, and P2 receptors attenuated Up 4 A-induced coronary relaxation more, while the effect of P2X 1 -blockade was similar and the effects of A 2A - and P2Y 1 -blockade were reduced in AoB as compared to Sham. mRNA expression of neither A1, A2, A3, nor P2X 1 , P2X 7 , P2Y 1 , P2Y 2 , nor P2Y 6 -receptors was altered in AoB as compared to Sham, while P2Y 12 expression was higher in AoB. eNOS inhibition attenuated Up 4 A-induced coronary relaxation in both Sham and AoB. Additional blockade of cyclooxygenase enhanced Up 4 A-induced coronary relaxation in AoB but not Sham swine, suggesting the involvement of vasoconstrictor prostanoids. In endothelium-denuded coronary small arteries from normal swine, thromboxane synthase (TxS) inhibition enhanced relaxation to Up 4 A compared to endothelium-intact arteries, to a similar extent as P2Y 12 inhibition, while the combination inhibition of P2Y 12 and TxS had no additional effect. In conclusion, Up 4 A-induced coronary relaxation is blunted in swine with AoB, which appears to be due to the production of a vasoconstrictor prostanoid, likely thromboxane A 2 .

Neuroprotective effects of testosterone metabolites and dependency on receptor action on the morphology of somatic motoneurons following the death of neighboring motoneurons.

PubMed

Cai, Yi; Chew, Cory; Muñoz, Fernando; Sengelaub, Dale R

2017-06-01

Partial depletion of spinal motoneuron populations induces dendritic atrophy in neighboring motoneurons, and treatment with testosterone is neuroprotective, attenuating induced dendritic atrophy. In this study we examined whether the protective effects of testosterone could be mediated via its androgenic or estrogenic metabolites. Furthermore, to assess whether these neuroprotective effects were mediated through steroid hormone receptors, we used receptor antagonists to attempt to prevent the neuroprotective effects of hormones after partial motoneuron depletion. Motoneurons innervating the vastus medialis muscles of adult male rats were selectively killed by intramuscular injection of cholera toxin-conjugated saporin. Simultaneously, some saporin-injected rats were treated with either dihydrotestosterone or estradiol, alone or in combination with their respective receptor antagonists, or left untreated. Four weeks later, motoneurons innervating the ipsilateral vastus lateralis muscle were labeled with cholera toxin-conjugated horseradish peroxidase, and dendritic arbors were reconstructed in three dimensions. Compared with intact normal animals, partial motoneuron depletion resulted in decreased dendritic length in remaining quadriceps motoneurons. Dendritic atrophy was attenuated with both dihydrotestosterone and estradiol treatment to a degree similar to that seen with testosterone, and attenuation of atrophy was prevented by receptor blockade. Together, these findings suggest that neuroprotective effects on motoneurons can be mediated by either androgenic or estrogenic hormones and require action via steroid hormone receptors, further supporting a role for hormones as neurotherapeutic agents in the injured nervous system. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 691-707, 2017. © 2016 Wiley Periodicals, Inc.

Cannabinoid receptor 1 inhibition improves cardiac function and remodelling after myocardial infarction and in experimental metabolic syndrome.

PubMed

Slavic, Svetlana; Lauer, Dilyara; Sommerfeld, Manuela; Kemnitz, Ulrich Rudolf; Grzesiak, Aleksandra; Trappiel, Manuela; Thöne-Reineke, Christa; Baulmann, Johannes; Paulis, Ludovit; Kappert, Kai; Kintscher, Ulrich; Unger, Thomas; Kaschina, Elena

2013-07-01

The cannabinoid receptors, CB1 and CB2, are expressed in the heart, but their role under pathological conditions remains controversial. This study examined the effect of CB1 receptor blockade on cardiovascular functions after experimental MI and in experimental metabolic syndrome. MI was induced in Wistar rats by permanent ligation of the left coronary artery. Treatment with the CB1 receptor antagonist rimonabant (10 mg/kg i.p. daily) started 7 days before or 6 h after MI and continued for 6 weeks. Haemodynamic parameters were measured via echocardiography and intracardiac Samba catheter. CB1 blockade improved systolic and diastolic heart function, decreased cardiac collagen and hydroxyproline content and down-regulated TGF-β1. Additionally, rimonabant decreased arterial stiffness, normalised QRS complex duration and reduced brain natriuretic peptide levels in serum. In primary cardiac fibroblasts, rimonabant decreased MMP-9 activity and TGF-β1 expression. Furthermore, rimonabant improved depressed systolic function of spontaneously hypertensive obese rats and reduced weight gain. Blocking of CB1 receptor with rimonabant improves cardiac functions in the early and late stages after MI, decreases arterial stiffness and reduces cardiac remodelling. Rimonabant also has cardioprotective actions in rats characterised by the metabolic syndrome. Inhibition of proteolysis and TGF-β1 expression and reduced collagen content by rimonabant may attenuate destruction of the extracellular matrix and decrease fibrosis after MI.

NMDA receptor blockade in the prelimbic cortex activates the mesolimbic system and dopamine-dependent opiate reward signaling.

PubMed

Tan, Huibing; Rosen, Laura G; Ng, Garye A; Rushlow, Walter J; Laviolette, Steven R

2014-12-01

N-Methyl-D-aspartate (NMDA) receptors in the medial prefrontal cortex (mPFC) are involved in opiate reward processing and modulate sub-cortical dopamine (DA) activity. NMDA receptor blockade in the prelimbic (PLC) division of the mPFC strongly potentiates the rewarding behavioural properties of normally sub-reward threshold doses of opiates. However, the possible functional interactions between cortical NMDA and sub-cortical DAergic motivational neural pathways underlying these effects are not understood. This study examines how NMDA receptor modulation in the PLC influences opiate reward processing via interactions with sub-cortical DAergic transmission. We further examined whether direct intra-PLC NMDA receptor modulation may activate DA-dependent opiate reward signaling via interactions with the ventral tegmental area (VTA). Using an unbiased place conditioning procedure (CPP) in rats, we performed bilateral intra-PLC microinfusions of the competitive NMDA receptor antagonist, (2R)-amino-5-phosphonovaleric acid (AP-5), prior to behavioural morphine place conditioning and challenged the rewarding effects of morphine with DA receptor blockade. We next examined the effects of intra-PLC NMDA receptor blockade on the spontaneous activity patterns of presumptive VTA DA or GABAergic neurons, using single-unit, extracellular in vivo neuronal recordings. We show that intra-PLC NMDA receptor blockade strongly activates sub-cortical DA neurons within the VTA while inhibiting presumptive non-DA GABAergic neurons. Behaviourally, NMDA receptor blockade activates a DA-dependent opiate reward system, as pharmacological blockade of DA transmission blocked morphine reward only in the presence of intra-PLC NMDA receptor antagonism. These findings demonstrate a cortical NMDA-mediated mechanism controlling mesolimbic DAergic modulation of opiate reward processing.

Double blockade of angiotensin II (AT1)-receptors and ACE does not improve weight gain and glucose homeostasis better than single-drug treatments in obese rats

PubMed Central

Miesel, Anja; Müller-Fielitz, Helge; Jöhren, Olaf; Vogt, Florian M; Raasch, Walter

2012-01-01

BACKGROUND AND PURPOSE Combination therapies are becoming increasingly important for the treatment of high blood pressure. Little is known about whether double blockade of angiotensin II (AT1) receptors and angiotensin-converting enzyme (ACE) exert synergistic metabolic effects. EXPERIMENTAL APPROACH Spontaneously hypertensive rats were allowed to choose between palatable chocolate bars and standard chow and were simultaneously treated with the AT1 blocker telmisartan (8 mg·kgbw−1·day−1), the ACE inhibitor ramipril (4 mg·kgbw−1·day−1) or a combination of the two (8 + 4 mg·kgbw−1·day−1) for 12 weeks. KEY RESULTS Although food-dependent energy intake was increased by telmisartan and telmisartan + ramipril compared with ramipril or controls, body weight gain, abundance of fat and plasma leptin levels were decreased. Increased insulin levels in response to an oral glucose tolerance test were comparably attenuated by telmisartan and telmisartan + ramipril, but not by ramipril. During an insulin tolerance test, glucose utilization was equally as effectively improved by telmisartan and telmisartan + ramipril. In response to a stress test, ACTH, corticosterone and glucose increased in controls. These stress reactions were attenuated by telmisartan and telmisartan + ramipril. CONCLUSIONS AND IMPLICATIONS The combination of telmisartan + ramipril was no more efficacious in regulating body weight and glucose homeostasis than telmisartan alone. However, telmisartan was more effective than ramipril in improving metabolic parameters and in reducing body weight. The association between the decrease in stress responses and the diminished glucose levels after stress supports our hypothesis that the ability of telmisartan, as an AT1 receptor blocker, to alleviate stress reactions may contribute to its hypoglycaemic actions. PMID:22014027

Coupling to protein kinases A and C of adenosine A2B receptors involved in the facilitation of noradrenaline release in the prostatic portion of rat vas deferens.

PubMed

Queiroz, Glória; Quintas, Clara; Talaia, Carlos; Gonçalves, Jorge

2004-08-01

In the prostatic portion of rat vas deferens, the non-selective adenosine receptor agonist NECA (0.1-30 microM), but not the A(2A) agonist CGS 21680 (0.001-10 microM), caused a facilitation of electrically evoked noradrenaline release (up to 43 +/- 4%), when inhibitory adenosine A(1) receptors were blocked. NECA-elicited facilitation of noradrenaline release was prevented by the A(2B) receptor-antagonist MRS 1754, enhanced by preventing cyclic-AMP degradation with rolipram, abolished by the protein kinase A inhibitors H-89, KT 5720 and cyclic-AMPS-Rp and attenuated by the protein kinase C inhibitors Ro 32-0432 and calphostin C. The adenosine uptake inhibitor NBTI also elicited a facilitation of noradrenaline release; an effect that was abolished by adenosine deaminase and attenuated by MRS 1754, by inhibitors of the extracellular nucleotide metabolism and by blockade of alpha(1)-adrenoceptors and P2X receptors with prazosin and NF023, respectively. It was concluded that adenosine A(2B) receptors are involved in a facilitation of noradrenaline release in the prostatic portion of rat vas deferens that can be activated by adenosine formed by extracellular catabolism of nucleotides. The receptors seem to be coupled to the adenylyl cyclase-protein kinase A pathway but activation of the protein kinase C by protein kinase A, may also contribute to the adenosine A(2B) receptor-mediated facilitation of noradrenaline release.

Selective blockade of TRPA1 channel attenuates pathological pain without altering noxious cold sensation or body temperature regulation.

PubMed

Chen, Jun; Joshi, Shailen K; DiDomenico, Stanley; Perner, Richard J; Mikusa, Joe P; Gauvin, Donna M; Segreti, Jason A; Han, Ping; Zhang, Xu-Feng; Niforatos, Wende; Bianchi, Bruce R; Baker, Scott J; Zhong, Chengmin; Simler, Gricelda H; McDonald, Heath A; Schmidt, Robert G; McGaraughty, Steve P; Chu, Katharine L; Faltynek, Connie R; Kort, Michael E; Reilly, Regina M; Kym, Philip R

2011-05-01

Despite the increasing interest in TRPA1 channel as a pain target, its role in cold sensation and body temperature regulation is not clear; the efficacy and particularly side effects resulting from channel blockade remain poorly understood. Here we use a potent, selective, and bioavailable antagonist to address these issues. A-967079 potently blocks human (IC(50): 51 nmol/L, electrophysiology, 67 nmol/L, Ca(2+) assay) and rat TRPA1 (IC(50): 101 nmol/L, electrophysiology, 289 nmol/L, Ca(2+) assay). It is >1000-fold selective over other TRP channels, and is >150-fold selective over 75 other ion channels, enzymes, and G-protein-coupled receptors. Oral dosing of A-967079 produces robust drug exposure in rodents, and exhibits analgesic efficacy in allyl isothiocyanate-induced nocifensive response and osteoarthritic pain in rats (ED(50): 23.2 mg/kg, p.o.). A-967079 attenuates cold allodynia produced by nerve injury but does not alter noxious cold sensation in naive animals, suggesting distinct roles of TRPA1 in physiological and pathological states. Unlike TRPV1 antagonists, A-967079 does not alter body temperature. It also does not produce locomotor or cardiovascular side effects. Collectively, these data provide novel insights into TRPA1 function and suggest that the selective TRPA1 blockade may present a viable strategy for alleviating pain without untoward side effects. Copyright © 2011 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Systemic blockade of nicotinic and purinergic receptors inhibits ventilation and increases apnoea frequency in newborn rats.

PubMed

Niane, Lalah M; Joseph, Vincent; Bairam, Aida

2012-08-01

We hypothesized that the combined blockade of peripheral cholinergic and purinergic receptors alters the baseline breathing pattern and respiratory responses to carotid body stimuli (hypoxia, hyperoxia and hypercapnia). Rat pups at 4 (P4) and 12 days of postnatal age (P12) received an intraperitoneal injection of either saline vehicle or hexamethonium + suramin (Hex, 1 mg kg(-1), nicotinic receptor antagonist; Sur, 40 mg kg(-1), P2X receptor antagonist; both of which act mainly on peripheral receptors). Compared with the control animals (saline-injected rats), the Hex + Sur-treated rats demonstrated the following features: (1) decreased baseline ventilation and increased frequency of apnoea and breath-by-breath irregularities, with a larger effect in the P4 than in the P12 rats; (2) a decreased peak minute ventilation and respiratory frequency response to hypoxia (fractional inspired oxygen 12%), with a greater effect in the P12 than in the P4 rats; (3) an attenuated decline of the respiratory frequency during hyperoxia (fractional inspired oxygen 50%) to a similar magnitude in rats of both ages; and (4) a decreased hypercapnic ventilatory response (fractional inspired carbon dioxide 5%) to a similar magnitude in rats of both ages. We conclude that the cholinergic nicotinic and purinergic P2X receptors are essential to maintain an adequate baseline pattern in normoxia. They also contribute, albeit not exclusively, to the hypoxic ventilatory response, with an age-specific effect, most probably linked to the cholinergic component, which might partly underlie the postnatal maturation of peripheral chemoreceptors.

ARF6-dependent regulation of P2Y receptor traffic and function in human platelets.

PubMed

Kanamarlapudi, Venkateswarlu; Owens, Sian E; Saha, Keya; Pope, Robert J; Mundell, Stuart J

2012-01-01

Adenosine diphosphate (ADP) is a critical regulator of platelet activation, mediating its actions through two G protein-coupled receptors, the P2Y(1) and P2Y(12) purinoceptors. Recently, we demonstrated that P2Y(1) and P2Y(12) purinoceptor activities are rapidly and reversibly modulated in human platelets, revealing that the underlying mechanism requires receptor internalization and subsequent trafficking as an essential part of this process. In this study we investigated the role of the small GTP-binding protein ADP ribosylation factor 6 (ARF6) in the internalization and function of P2Y(1) and P2Y(12) purinoceptors in human platelets. ARF6 has been implicated in the internalization of a number of GPCRs, although its precise molecular mechanism in this process remains unclear. In this study we show that activation of either P2Y(1) or P2Y(12) purinoceptors can stimulate ARF6 activity. Further blockade of ARF6 function either in cell lines or human platelets blocks P2Y purinoceptor internalization. This blockade of receptor internalization attenuates receptor resensitization. Furthermore, we demonstrate that Nm23-H1, a nucleoside diphosphate (NDP) kinase regulated by ARF6 which facilitates dynamin-dependent fission of coated vesicles during endocytosis, is also required for P2Y purinoceptor internalization. These data describe a novel function of ARF6 in the internalization of P2Y purinoceptors and demonstrate the integral importance of this small GTPase upon platelet ADP receptor function.

Dopaminergic Modulation of Risky Decision-Making

PubMed Central

Simon, Nicholas W.; Montgomery, Karienn S.; Beas, Blanca S.; Mitchell, Marci R.; LaSarge, Candi L.; Mendez, Ian A.; Bañuelos, Cristina; Vokes, Colin M.; Taylor, Aaron B.; Haberman, Rebecca P.; Bizon, Jennifer L.; Setlow, Barry

2012-01-01

Many psychiatric disorders are characterized by abnormal risky decision-making and dysregulated dopamine receptor expression. The current study was designed to determine how different dopamine receptor subtypes modulate risk-taking in young adult rats, using a “Risky Decision-making Task” that involves choices between small “safe” rewards and large “risky” rewards accompanied by adverse consequences. Rats showed considerable, stable individual differences in risk preference in the task, which were not related to multiple measures of reward motivation, anxiety, or pain sensitivity. Systemic activation of D2-like receptors robustly attenuated risk-taking, whereas drugs acting on D1-like receptors had no effect. Systemic amphetamine also reduced risk-taking, an effect which was attenuated by D2-like (but not D1-like) receptor blockade. Dopamine receptor mRNA expression was evaluated in a separate cohort of drug-naive rats characterized in the task. D1 mRNA expression in both nucleus accumbens shell and insular cortex was positively associated with risk-taking, while D2 mRNA expression in orbitofrontal and medial prefrontal cortex predicted risk preference in opposing nonlinear patterns. Additionally, lower levels of D2 mRNA in dorsal striatum were associated with greater risk-taking. These data strongly implicate dopamine signaling in prefrontal corticalstriatal circuitry in modulating decision-making processes involving integration of reward information with risks of adverse consequences. PMID:22131407

Dopamine Attenuates Ketamine-Induced Neuronal Apoptosis in the Developing Rat Retina Independent of Early Synchronized Spontaneous Network Activity.

PubMed

Dong, Jing; Gao, Lingqi; Han, Junde; Zhang, Junjie; Zheng, Jijian

2017-07-01

Deprivation of spontaneous rhythmic electrical activity in early development by anesthesia administration, among other interventions, induces neuronal apoptosis. However, it is unclear whether enhancement of neuronal electrical activity attenuates neuronal apoptosis in either normal development or after anesthesia exposure. The present study investigated the effects of dopamine, an enhancer of spontaneous rhythmic electrical activity, on ketamine-induced neuronal apoptosis in the developing rat retina. TUNEL and immunohistochemical assays indicated that ketamine time- and dose-dependently aggravated physiological and ketamine-induced apoptosis and inhibited early-synchronized spontaneous network activity. Dopamine administration reversed ketamine-induced neuronal apoptosis, but did not reverse the inhibitory effects of ketamine on early synchronized spontaneous network activity despite enhancing it in controls. Blockade of D1, D2, and A2A receptors and inhibition of cAMP/PKA signaling partially antagonized the protective effect of dopamine against ketamine-induced apoptosis. Together, these data indicate that dopamine attenuates ketamine-induced neuronal apoptosis in the developing rat retina by activating the D1, D2, and A2A receptors, and upregulating cAMP/PKA signaling, rather than through modulation of early synchronized spontaneous network activity.

Cannabinoid reward and aversion effects in the posterior ventral tegmental area are mediated through dissociable opiate receptor subtypes and separate amygdalar and accumbal dopamine receptor substrates.

PubMed

Ahmad, Tasha; Laviolette, Steven R

2017-08-01

The ventral tegmental area (VTA) and its projections to the basolateral amygdala (BLA) and nucleus accumbens (NAc) are critical for cannabinoid-related motivational effects. Cannabinoid CB1 receptor (CB1R) transmission modulates VTA dopamine (DA) neuron activity and previous reports demonstrate anatomically segregated effects of CB1R transmission in the VTA. However, the underlying pharmacological and anatomical regions responsible for these effects are currently unknown. The objective of the study is to characterize the motivational effects of localized anterior vs. posterior intra-VTA activation vs. blockade of CB1R transmission and the potential role of intra-BLA and intra-NAc DA transmission in these phenomena. Using a conditioned place preference (CPP) procedure, we administered a CB1 agonist (WIN-55,212-2) or antagonist (AM 251) into the posterior VTA (pVTA) or anterior VTA (aVTA) of rats, combined with intra-BLA or intra-NAc DA receptor blockade and intra-VTA co-administration of selective mu vs. kappa opiate-receptor antagonists. Intra-pVTA CB1R activation produced robust rewarding effects through a mu-opiate receptor mechanism whereas CB1R blockade produced conditioned place aversions (CPA) through a kappa-opiate receptor substrate. In contrast, modulation of aVTA CB1R transmission produced no observable effects. Intra-BLA DA receptor blockade prevented the rewarding effects of pVTA CB1R activation, but had no effects on CB1R blockade-induced aversions. In contrast, intra-NAc DA receptor blockade selectively blocked the aversive effects of pVTA CB1R antagonism. Activation vs. blockade of CB1R transmission in the posterior VTA produces bivalent rewarding or aversive effects through separate mu vs. kappa-opiate receptor substrates. These dissociable effects depend on separate DA receptor transmission substrates in the BLA or NAc, respectively.

GABAa and GABAc receptor-mediated modulation of responses to color stimuli: electroretinographic study in the turtle Emys orbicularis.

PubMed

Kupenova, Petia; Vitanova, Lily; Popova, Elka

2010-04-01

GABAergic transmission is involved in color coding in the retina. The specific contribution of different GABA receptors to spectral sensitivity of the retinal responses is not well characterized. We studied GABAa and GABAc receptor-mediated effects on the intensity-response functions of the electroretinographic ON (b-wave) and OFF (d-wave) responses to color stimuli. For this purpose, we compared the effects of GABAa receptor blockade by bicuculline with the effects of GABAa + GABAc receptor blockade by picrotoxin. The blockade of both GABAa and GABAc receptors caused an amplitude increase of the electroretinographic responses, but the effects of the two blockades depended in a specific manner on stimulus intensity and wavelength. The effects of GABAa receptor blockade showed distinct color ON/OFF asymmetry. The absolute and relative sensitivities of the ON responses to blue stimuli and OFF responses to red stimuli were increased to the greatest degree while the sensitivity of the ON responses to red stimuli and OFF responses to blue stimuli was least increased. In contrast, color ON/OFF asymmetry was not typical of the effects of GABAc receptor blockade. The most prominent GABAc effect was the sensitivity increase of the ON and OFF responses to blue stimuli and, to some lesser extent, to green stimuli. The results of this study indicate a specific role of GABAa and GABAc receptor-mediated influences in processing of chromatic information in the distal retina.

Increased GABA(A) inhibition of the RVLM after hindlimb unloading in rats

NASA Technical Reports Server (NTRS)

Moffitt, Julia A.; Heesch, Cheryl M.; Hasser, Eileen M.

2002-01-01

Attenuated baroreflex-mediated increases in renal sympathetic nerve activity (RSNA) in hindlimb unloaded (HU) rats apparently are due to changes within the central nervous system. We hypothesized that GABA(A) receptor-mediated inhibition of the rostral ventrolateral medulla (RVLM) is increased after hindlimb unloading. Responses to bilateral microinjection of the GABA(A) antagonist (-)-bicuculline methiodide (BIC) into the RVLM were examined before and during caudal ventrolateral medulla (CVLM) inhibition in Inactin-anesthetized control and HU rats. Increases in mean arterial pressure (MAP), heart rate (HR), and RSNA in response to BIC in the RVLM were significantly enhanced in HU rats. Responses to bilateral CVLM blockade were not different. When remaining GABA(A) inhibition in the RVLM was blocked by BIC during CVLM inhibition, the additional increases in MAP and RSNA were significantly greater in HU rats. These data indicate that GABA(A) receptor-mediated inhibition of RVLM neurons is augmented after hindlimb unloading. Effects of input from the CVLM were unaltered. Thus, after cardiovascular deconditioning in rodents, the attenuated increase in sympathetic nerve activity in response to hypotension is associated with greater GABA(A) receptor-mediated inhibition of RVLM neurons originating at least in part from sources other than the CVLM.

Effects of horizontal body casting on the baroreceptor reflex control of heart rate

NASA Technical Reports Server (NTRS)

Billman, G. E.; Dickey, D. T.; Sandler, H.; Stone, H. L.

1982-01-01

The purpose of this study was to investigate the effects of long-term horizontal body position on baroreceptor reflex control of heart rate. Six male rhesus monkeys (6.2-9.4 kg) were given bolus injections of 4.0 microgram/kg, phenylephrine during each of the following conditions: awake, anesthetized (10 mg/kg ketamine HCl), and after beta-blockade (1 mg/kg propranolol HCl) before, 7, 14, and 28 days after being placed in a horizontal body cast. R-R interval vs. systolic arterial pressure was plotted, and the slope was determined by least-squares-fit linear regression. Baroreceptor slope was significantly reduced by 7 days of horizontal body position and remained attenuated throughout the 28-day restraint period both before and after beta-receptor blockade. These data are consistent with the thesis that prolonged exposure to a zero-gravity environment impairs autonomic reflex regulation of the cardiovascular system.

[RAAS and insulin resistance].

PubMed

Motoshima, Hiroyuki; Araki, Eiichi

2012-09-01

The role of the renin-angiotensin-aldosterone system (RAAS) on the development of insulin resistance and type 2 diabetes (T2DM) is an area of growing interest. Most of the deleterious actions of the RAAS on insulin signals appear to be mediated through activation of the serine/threonine kinase, oxidative stress and tissue-inflammation in insulin-sensitive organs. Both experimental and clinical studies demonstrated that angiotensin II (Ang II) and aldosterone could play a role in the development of insulin resistance, diabetes and cardiovascular diseases. Large randomized clinical trials revealed that blockade of the RAAS with either angiotensin I converting enzyme inhibitors or AT1 receptor blockers results in decreased T2DM incidence, with a minor attenuation of markers for insulin resistance. This review focuses on the role of RAAS in the pathogenesis of insulin resistance, as well as on clinical relevance of RAAS blockade in the prevention and treatment of the metabolic syndrome and pre-diabetes.

Renin-angiotensin system (RAS) blockade attenuates growth and metastatic potential of renal cell carcinoma in mice.

PubMed

Araújo, Wedson F; Naves, Marcelo A; Ravanini, Juliana N; Schor, Nestor; Teixeira, Vicente P C

2015-09-01

Renal cell carcinoma (RCC) is the most frequent type of cancer among renal neoplasms in adults and responds poorly to radiotherapy and chemotherapy. There is evidence that blockade of the renin-angiotensin system (RAS) might have antineoplastic effects. The aim of this study was to investigate the effects of RAS blockade on RCC in a murine model. Murine renal cancer cells (Renca) were injected (1 × 10(5)) into the subcapsular space of the left kidney of BALB/c mice (8 wk of age). The animals were divided into 4 groups: a control group (no treatment), angiotensin-receptor blockers group (losartan 100mg/kg/d), angiotensin-converting enzyme inhibitor group (captopril 10mg/kg/d), and angiotensin-receptor blockers +angiotensin-converting enzyme inhibitor group (losartan 100mg/kg/d +captopril 10mg/kg/d). The animals received the drugs by gavage for 21 days after inoculation, beginning 2 days before tumor induction, and were then euthanized. After killing the animals, the kidneys and lungs were removed, weighed, and processed for histopathological and immunohistochemical analyses. Angiogenesis and vascular microvessels were assessed with the antibodies anti-vascular endothelial growth factor and anti-CD34. Angiotensin II-inoculated animals developed renal tumors. Treated animals presented smaller tumors, regardless of the therapeutic regimen, and far fewer lung metastases in both quantity and dimension compared with the controls. The expression of vascular endothelial growth factor and CD34 were significantly decreased in renal tumors of treated animals compared with the controls. Our findings suggest that blockade of RAS decreases tumor proliferation and metastatic capacity of RCC in this experimental model. Copyright © 2015 Elsevier Inc. All rights reserved.

P2X3 and P2X2/3 Receptors Play a Crucial Role in Articular Hyperalgesia Development Through Inflammatory Mechanisms in the Knee Joint Experimental Synovitis.

PubMed

Teixeira, Juliana Maia; Bobinski, Franciane; Parada, Carlos Amílcar; Sluka, Kathleen A; Tambeli, Cláudia Herrera

2017-10-01

Osteoarthritis (OA) is a degenerative and progressive disease characterized by cartilage breakdown and by synovial membrane inflammation, which results in disability, joint swelling, and pain. The purinergic P2X3 and P2X2/3 receptors contribute to development of inflammatory hyperalgesia, participate in arthritis processes in the knee joint, and are expressed in chondrocytes and nociceptive afferent fibers innervating the knee joint. In this study, we hypothesized that P2X3 and P2X2/3 receptors activation by endogenous ATP (adenosine 5'-triphosphate) induces articular hyperalgesia in the knee joint of male and female rats through an indirect sensitization of primary afferent nociceptors dependent on the previous release of pro-inflammatory cytokines and/or on neutrophil migration. We found that the blockade of articular P2X3 and P2X2/3 receptors significantly attenuated carrageenan-induced hyperalgesia in the knee joint of male and estrus female rats in a similar manner. The carrageenan-induced knee joint inflammation increased the expression of P2X3 receptors in chondrocytes of articular cartilage. Further, the blockade of articular P2X3 and P2X2/3 receptors significantly reduced the increased concentration of TNF-α, IL-6, and CINC-1 and the neutrophil migration induced by carrageenan. These findings indicate that P2X3 and P2X2/3 receptors activation by endogenous ATP is essential to hyperalgesia development in the knee joint through an indirect sensitization of primary afferent nociceptors dependent on the previous release of pro-inflammatory cytokines and/or on neutrophil migration.

Blockade of AT1 type receptors for angiotensin II prevents cardiac microvascular fibrosis induced by chronic stress in Sprague-Dawley rats.

PubMed

Firoozmand, Lília Taddeo; Sanches, Andrea; Damaceno-Rodrigues, Nilsa Regina; Perez, Juliana Dinéia; Aragão, Danielle Sanches; Rosa, Rodolfo Mattar; Marcondes, Fernanda Klein; Casarini, Dulce Elena; Caldini, Elia Garcia; Cunha, Tatiana Sousa

2018-04-20

To test the effects of chronic-stress on the cardiovascular system, the model of chronic mild unpredictable stress (CMS) has been widely used. The CMS protocol consists of the random, intermittent, and unpredictable exposure of laboratory animals to a variety of stressors, during 3 consecutive weeks. In this study, we tested the hypothesis that exposure to the CMS protocol leads to left ventricle microcirculatory remodeling that can be attenuated by angiotensin II receptor blockade. Male Sprague-Dawley rats were randomly assigned into four groups: Control, Stress, Control + losartan, and Stress + losartan (N = 6, each group, losartan: 20 mg/kg/day). The rats were euthanized 15 days after CMS exposure, and blood samples and left ventricle were collected. Rats submitted to CMS presented increased glycemia, corticosterone, noradrenaline and adrenaline concentration, and losartan reduced the concentration of the circulating amines. Cardiac angiotensin II, measured by high-performance liquid chromatography (HPLC), was significantly increased in the CMS group, and losartan treatment reduced it, while angiotensin 1-7 was significantly higher in the CMS losartan-treated group as compared with CMS. Histological analysis, verified by transmission electron microscopy, showed that rats exposed to CMS presented increased perivascular collagen and losartan effectively prevented the development of this process. Hence, CMS induced a state of microvascular disease, with increased perivascular collagen deposition, that may be the trigger for further development of cardiovascular disease. In this case, CMS fibrosis is associated with increased production of catecholamines and with a disruption of renin-angiotensin system balance, which can be prevented by angiotensin II receptor blockade.

Carbachol-induced long-term synaptic depression is enhanced during senescence at hippocampal CA3-CA1 synapses.

PubMed

Kumar, Ashok

2010-08-01

Dysregulation of the cholinergic transmitter system is a hallmark of Alzheimer's disease and contributes to an age-associated decline in memory performance. The current study examined the influence of carbachol, a cholinergic receptor agonist, on synaptic transmission over the course of aging. Extracellular excitatory postsynaptic field potentials were recorded from CA3-CA1 synapses in acute hippocampal slices obtained from young adult (5-8 mo) and aged (22-24 mo) male Fischer 344 rats. Bath application of carbachol elicited a transient depression of synaptic transmission, which was followed by a long-lasting depression (CCh-LTD) observed 90 min after carbachol cessation in both age groups. However, the magnitude of CCh-LTD was significantly larger in senescent animals and was attenuated by N-methyl-D-aspartate receptor blockade in aged animals. Blockade of L-type Ca(2+) channels inhibited CCh-LTD to a greater extent in aged animals compared to young adults. Finally, the expression of CCh-LTD was dependent on protein synthesis. The results indicate that altered Ca(2+) homeostasis or muscarinic activation of Ca(2+) signaling contribute to the enhanced CCh-LTD during senescence.

D1 Receptors Regulate Dendritic Morphology in Normal and Stressed Prelimbic Cortex

PubMed Central

Lin, Grant L.; Borders, Candace B.; Lundewall, Leslie J.; Wellman, Cara L.

2014-01-01

Both stress and dysfunction of prefrontal cortex are linked to psychological disorders, and structure and function of medial prefrontal cortex (mPFC) are altered by stress. Chronic restraint stress causes dendritic retraction in the prelimbic region (PL) of mPFC in rats. Dopamine release in mPFC increases during stress, and chronic administration of dopaminergic agonists results in dendritic remodeling. Thus, stress-induced alterations in dopaminergic transmission in PL may contribute to dendritic remodeling. We examined the effects of dopamine D1 receptor (D1R) blockade in PL during daily restraint stress on dendritic morphology in PL. Rats either underwent daily restraint stress (3 h/day, 10 days) or remained unstressed. In each group, rats received daily infusions of either the D1R antagonist SCH23390 or vehicle into PL prior to restraint; unstressed and stressed rats that had not undergone surgery were also examined. On the final day of restraint, rats were euthanized and brains were processed for Golgi histology. Pyramidal neurons in PL were reconstructed and dendritic morphology was quantified. Vehicle-infused stressed rats demonstrated dendritic retraction compared to unstressed rats, and D1R blockade in PL prevented this effect. Moreover, in unstressed rats, D1R blockade produced dendritic retraction. These effects were not due to attenuation of the HPA axis response to acute stress: plasma corticosterone levels in a separate group of rats that underwent acute restraint stress with or without D1R blockade were not significantly different. These findings indicate that dopaminergic transmission in mPFC during stress contributes directly to the stress-induced retraction of apical dendrites, while dopamine transmission in the absence of stress is important in maintaining normal dendritic morphology. PMID:25305546

D1 receptors regulate dendritic morphology in normal and stressed prelimbic cortex.

PubMed

Lin, Grant L; Borders, Candace B; Lundewall, Leslie J; Wellman, Cara L

2015-01-01

Both stress and dysfunction of prefrontal cortex are linked to psychological disorders, and structure and function of medial prefrontal cortex (mPFC) are altered by stress. Chronic restraint stress causes dendritic retraction in the prelimbic region (PL) of mPFC in rats. Dopamine release in mPFC increases during stress, and chronic administration of dopaminergic agonists results in dendritic remodeling. Thus, stress-induced alterations in dopaminergic transmission in PL may contribute to dendritic remodeling. We examined the effects of dopamine D1 receptor (D1R) blockade in PL during daily restraint stress on dendritic morphology in PL. Rats either underwent daily restraint stress (3h/day, 10 days) or remained unstressed. In each group, rats received daily infusions of either the D1R antagonist SCH23390 or vehicle into PL prior to restraint; unstressed and stressed rats that had not undergone surgery were also examined. On the final day of restraint, rats were euthanized and brains were processed for Golgi histology. Pyramidal neurons in PL were reconstructed and dendritic morphology was quantified. Vehicle-infused stressed rats demonstrated dendritic retraction compared to unstressed rats, and D1R blockade in PL prevented this effect. Moreover, in unstressed rats, D1R blockade produced dendritic retraction. These effects were not due to attenuation of the HPA axis response to acute stress: plasma corticosterone levels in a separate group of rats that underwent acute restraint stress with or without D1R blockade were not significantly different. These findings indicate that dopaminergic transmission in mPFC during stress contributes directly to the stress-induced retraction of apical dendrites, while dopamine transmission in the absence of stress is important in maintaining normal dendritic morphology. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mechanisms involved in oleamide-induced vasorelaxation in rat mesenteric resistance arteries.

PubMed

Sudhahar, Varadarajan; Shaw, Sean; Imig, John D

2009-04-01

Fatty acid amides are a new class of signaling lipids that have been implicated in diverse physiological and pathological conditions. Oleamide is a fatty acid amide that induces vasorelaxation. Here, we investigated the mechanisms behind the vasorelaxation effect of oleamide in rat mesenteric resistance arteries. Oleamide-induced concentration dependent (0.01 microM-10 microM) vasorelaxation in mesenteric resistance arteries. This relaxation was unaffected by the presence of the fatty acid amide hydrolase (FAAH) inhibitors. The cannabinoid type 1 (CB1) receptor antagonist, AM251 and the non-CB1/CB2 cannabinoid receptor antagonist, O-1918, attenuated the oleamide vasodilatory response, however the cannabinoid CB2 receptor antagonist, AM630, did not affect the vascular response. Moreover, inhibition of the transient receptor potential vanilloid (TRPV) 1 receptor with capsazepine shifted the oleamide-induced vasorelaxation response to the right. In agreement with the vascular functional data, the cannabinoid CB1 and TRPV1 receptor proteins were expressed in mesenteric resistance arteries but cannabinoid CB2 receptors and the FAAH enzyme were not. In endothelium-denuded arteries, the oleamide-mediated vasorelaxation was attenuated and cannabinoid CB1 or non-CB1/CB2 cannabinoid receptor blockade did not further reduce the dilatory response whereas TRPV1 antagonism further decreased the response. These findings indicate that cannabinoid receptors on the endothelium and endothelium-independent TRPV1 receptors contribute to the oleamide vasodilatory response. Taken together, these results demonstrate that the oleamide-induced vasorelaxation is mediated, in part, by cannabinoid CB1 receptors, non-CB1/CB2 cannabinoid receptors, and TRPV1 receptors in rat mesenteric resistance arteries. These mechanisms are overlapping in respect to oleamide-induced mesenteric resistance artery dilation.

Mechanisms involved in oleamide-induced vasorelaxation in rat mesenteric resistance arteries

PubMed Central

Sudhahar, Varadarajan; Shaw, Sean; Imig, John D.

2009-01-01

Fatty acid amides are a new class of signaling lipids that have been implicated in diverse physiological and pathological conditions. Oleamide is a fatty acid amide that induces vasorelaxation. Here, we investigated the mechanisms behind the vasorelaxation effect of oleamide in rat mesenteric resistance arteries. Oleamide-induced concentration dependent (0.01 μM–10μM) vasorelaxation in mesenteric resistance arteries. This relaxation was unaffected by the presence of the fatty acid amide hydrolase (FAAH) inhibitors. The cannabinoid type 1 (CB1) receptor antagonist, AM251 and the non-CB1/CB2 cannabinoid receptor antagonist, O-1918, attenuated the oleamide vasodilatory response, however the cannabinoid CB2 receptor antagonist, AM630, did not affect the vascular response. Moreover, inhibition of the transient receptor potential vanilloid (TRPV) 1 receptor with capsazepine shifted the oleamide-induced vasorelaxation response to the right. In agreement with the vascular functional data, the cannabinoid CB1 and TRPV1 receptor proteins were expressed in mesenteric resistance arteries but cannabinoid CB2 receptors and the FAAH enzyme were not. In endothelium-denuded arteries, the oleamide-mediated vasorelaxation was attenuated and cannabinoid CB1 or non-CB1/CB2 cannabinoid receptor blockade did not further reduce the dilatory response whereas TRPV1 antagonism further decreased the response. These findings indicate that cannabinoid receptors on the endothelium and endothelium-independent TRPV1 receptors contribute to the oleamide vasodilatory response. Taken together, these results demonstrate that the oleamide-induced vasorelaxation is mediated, in part, by cannabinoid CB1 receptors, non-CB1/CB2 cannabinoid receptors, and TRPV1 receptors in rat mesenteric resistance arteries. These mechanisms are overlapping in respect to oleamide-induced mesenteric resistance artery dilation. PMID:19326479

MK-801 protection against methamphetamine-induced striatal dopamine terminal injury is associated with attenuated dopamine overflow.

PubMed

Weihmuller, F B; O'Dell, S J; Marshall, J F

1992-06-01

Repeated administrations of methamphetamine (m-AMPH) produce high extracellular levels of dopamine (DA) and subsequent striatal DA terminal damage. Pharmacological blockade of N-methyl-D-aspartate (NMDA) receptors has been shown previously to prevent m-AMPH-induced striatal DA terminal injury, but the mechanism for this protection is unclear. In the present study, in vivo microdialysis was used to determine the effects of blockade of NMDA receptors with the noncompetitive antagonist MK-801 on m-AMPH-induced striatal DA overflow. Four injections of MK-801 (0.5 mg/kg, ip) alone did not significantly change extracellular striatal DA concentrations from pretreatment values. Four treatments with m-AMPH (4.0 mg/kg, sc at 2-hr intervals) increased striatal DA overflow, and the overflow was particularly extensive following the fourth injection. This m-AMPH regimen produced a 40% reduction in striatal DA tissue content 1 week later. Treatment with MK-801 15 min before each of the four m-AMPH injections or prior to only the last two m-AMPH administrations attenuated the m-AMPH-induced increase in striatal DA overflow and protected completely against striatal DA depletions. Other MK-801 treatment regimens less effectively reduced the m-AMPH-induced striatal DA efflux and were ineffective in protecting against striatal DA depletions. Linear regression analysis indicated that cumulative DA overflow was strongly predictive (r = -.68) of striatal DA tissue levels measured one week later. These findings suggest that the extensive DA overflow seen during a neurotoxic regimen of m-AMPH is a crucial component of the subsequent neurotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacological endothelin receptor interaction does not occur in veins from ET(B) receptor deficient rats.

PubMed

Thakali, Keshari; Galligan, James J; Fink, Gregory D; Gariepy, Cheryl E; Watts, Stephanie W

2008-07-01

Heterodimerization of G-protein coupled receptors can alter receptor pharmacology. ET A and ET B receptors heterodimerize when co-expressed in heterologous expression lines. We hypothesized that ET A and ET B receptors heterodimerize and pharmacologically interact in vena cava from wild-type (WT) but not ET B receptor deficient (sl/sl) rats. Pharmacological endothelin receptor interaction was assessed by comparing ET-1-induced contraction in rings of rat thoracic aorta and thoracic vena cava from male Sprague Dawley rats under control conditions, ET A receptor blockade (atrasentan, 10 nM), ET B receptor blockade (BQ-788, 100 nM) or ET B receptor desensitization (Sarafotoxin 6c, 100 nM) and ET A plus ET B receptor blockade or ET A receptor blockade plus ET B receptor desensitization. In addition, similar pharmacological ET receptor antagonism experiments were performed in rat thoracic aorta and vena cava from WT and sl/sl rats. ET A but not ET B receptor blockade or ET B receptor desensitization inhibited aortic and venous ET-1-induced contraction. In vena cava but not aorta, when ET B receptors were blocked (BQ-788, 100 nM) or desensitized (S6c, 100 nM), atrasentan caused a greater inhibition of ET-1-induced contraction. Vena cava from WT but not sl/sl rats exhibited similar pharmacological ET receptor interaction. Immunocytochemistry was performed on freshly dissociated aortic and venous vascular smooth muscle cells to determine localization of ET A and ET B receptors. ET A and ET B receptors qualitatively co-localized more strongly to the plasma membrane of aortic compared to venous vascular smooth muscle cells. Our data suggest that pharmacological ET A and ET B receptor interaction may be dependent on the presence of functional ET B receptors and independent of receptor location.

Supersensitive Kappa Opioid Receptors Promotes Ethanol Withdrawal-Related Behaviors and Reduce Dopamine Signaling in the Nucleus Accumbens.

PubMed

Rose, Jamie H; Karkhanis, Anushree N; Chen, Rong; Gioia, Dominic; Lopez, Marcelo F; Becker, Howard C; McCool, Brian A; Jones, Sara R

2016-05-01

Chronic ethanol exposure reduces dopamine transmission in the nucleus accumbens, which may contribute to the negative affective symptoms associated with ethanol withdrawal. Kappa opioid receptors have been implicated in withdrawal-induced excessive drinking and anxiety-like behaviors and are known to inhibit dopamine release in the nucleus accumbens. The effects of chronic ethanol exposure on kappa opioid receptor-mediated changes in dopamine transmission at the level of the dopamine terminal and withdrawal-related behaviors were examined. Five weeks of chronic intermittent ethanol exposure in male C57BL/6 mice were used to examine the role of kappa opioid receptors in chronic ethanol-induced increases in ethanol intake and marble burying, a measure of anxiety/compulsive-like behavior. Drinking and marble burying were evaluated before and after chronic intermittent ethanol exposure, with and without kappa opioid receptor blockade by nor-binaltorphimine (10mg/kg i.p.). Functional alterations in kappa opioid receptors were assessed using fast scan cyclic voltammetry in brain slices containing the nucleus accumbens. Chronic intermittent ethanol-exposed mice showed increased ethanol drinking and marble burying compared with controls, which was attenuated with kappa opioid receptor blockade. Chronic intermittent ethanol-induced increases in behavior were replicated with kappa opioid receptor activation in naïve mice. Fast scan cyclic voltammetry revealed that chronic intermittent ethanol reduced accumbal dopamine release and increased uptake rates, promoting a hypodopaminergic state of this region. Kappa opioid receptor activation with U50,488H concentration-dependently decreased dopamine release in both groups; however, this effect was greater in chronic intermittent ethanol-treated mice, indicating kappa opioid receptor supersensitivity in this group. These data suggest that the chronic intermittent ethanol-induced increase in ethanol intake and anxiety/compulsive-like behaviors may be driven by greater kappa opioid receptor sensitivity and a hypodopaminergic state of the nucleus accumbens. © The Author 2015. Published by Oxford University Press on behalf of CINP.

Endogenous peptide YY and neuropeptide Y inhibit colonic ion transport, contractility and transit differentially via Y1 and Y2 receptors

PubMed Central

Tough, IR; Forbes, S; Tolhurst, R; Ellis, M; Herzog, H; Bornstein, JC; Cox, HM

2011-01-01

BACKGROUND AND PURPOSE Peptide YY (PYY) and neuropeptide Y (NPY) activate Y receptors, targets under consideration as treatments for diarrhoea and other intestinal disorders. We investigated the gastrointestinal consequences of selective PYY or NPY ablation on mucosal ion transport, smooth muscle activity and transit using wild-type, single and double peptide knockout mice, comparing mucosal responses with those from human colon. EXPERIMENTAL APPROACH Mucosae were pretreated with a Y1 (BIBO3304) or Y2 (BIIE0246) receptor antagonist and changes in short-circuit current recorded. Colonic transit and colonic migrating motor complexes (CMMCs) were assessed in vitro and upper gastrointestinal and colonic transit measured in vivo. KEY RESULTS Y receptor antagonists revealed tonic Y1 and Y2 receptor-mediated antisecretory effects in human and wild-type mouse colon mucosae. In both, Y1 tone was epithelial while Y2 tone was neuronal. Y1 tone was reduced 90% in PYY−/− mucosa but unchanged in NPY−/− tissue. Y2 tone was partially reduced in NPY−/− or PYY−/− mucosae and abolished in tetrodotoxin-pretreated PYY−/− tissue. Y1 and Y2 tone were absent in NPYPYY−/− tissue. Colonic transit was inhibited by Y1 blockade and increased by Y2 antagonism indicating tonic Y1 excitation and Y2 inhibition respectively. Upper GI transit was increased in PYY−/− mice only. Y2 blockade reduced CMMC frequency in isolated mouse colon. CONCLUSIONS AND IMPLICATIONS Endogenous PYY and NPY induced significant mucosal antisecretory tone mediated by Y1 and Y2 receptors, via similar mechanisms in human and mouse colon mucosa. Both peptides contributed to tonic Y2-receptor-mediated inhibition of colonic transit in vitro but only PYY attenuated upper GI transit. PMID:21457230

Involvement of prelimbic medial prefrontal cortex in panic-like elaborated defensive behaviour and innate fear-induced antinociception elicited by GABAA receptor blockade in the dorsomedial and ventromedial hypothalamic nuclei: role of the endocannabinoid CB1 receptor.

PubMed

Freitas, Renato Leonardo de; Salgado-Rohner, Carlos José; Hallak, Jaime Eduardo Cecílio; Crippa, José Alexandre de Souza; Coimbra, Norberto Cysne

2013-09-01

It has been shown that GABAA receptor blockade in the dorsomedial and ventromedial hypothalamic nuclei (DMH and VMH, respectively) induces elaborated defensive behavioural responses accompanied by antinociception, which has been utilized as an experimental model of panic attack. Furthermore, the prelimbic (PL) division of the medial prefrontal cortex (MPFC) has been related to emotional reactions and the processing of nociceptive information. The aim of the present study was to investigate the possible involvement of the PL cortex and the participation of local cannabinoid CB1 receptors in the elaboration of panic-like reactions and in innate fear-induced antinociception. Elaborated fear-induced responses were analysed during a 10-min period in an open-field test arena. Microinjection of the GABAA receptor antagonist bicuculline into the DMH/VMH evoked panic-like behaviour and fear-induced antinociception, which was decreased by microinjection of the non-selective synaptic contact blocker cobalt chloride in the PL cortex. Moreover, microinjection of AM251 (25, 100 or 400 pmol), an endocannabinoid CB1 receptor antagonist, into the PL cortex also attenuated the defensive behavioural responses and the antinociception that follows innate fear behaviour elaborated by DMH/VMH. These data suggest that the PL cortex plays an important role in the organization of elaborated forward escape behaviour and that this cortical area is also involved in the elaboration of innate fear-induced antinociception. Additionally, CB1 receptors in the PL cortex modulate both panic-like behaviours and fear-induced antinociception elicited by disinhibition of the DMH/VMH through microinjection of bicuculline.

Inhibition of the renin-angiotensin-aldosterone system: is there room for dual blockade in the cardiorenal continuum?

PubMed

Volpe, Massimo; Danser, A H Jan; Menard, Joël; Waeber, Bernard; Mueller, Dominik N; Maggioni, Aldo P; Ruilope, Luis M

2012-04-01

Antagonism of renin-angiotensin-aldosterone system is exerted through angiotensin-converting enzyme inhibitors, angiotensin receptor antagonists, renin inhibitors and mineralocorticoid receptor antagonists. These drugs have been successfully tested in numerous trials and in different clinical settings. The original indications of renin-angiotensin-aldosterone system blockers have progressively expanded from the advanced stages to the earlier stages of cardiorenal continuum. To optimize the degree of blockade of renin-angiotensin-aldosterone system, dose uptitrations of angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists or the use of a dual blockade, initially identified with the combination of angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists, have been proposed. The data from the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET) study do not support this specific dual blockade approach. However, the dual blockade of angiotensin-converting enzyme inhibitors/angiotensin receptor antagonists with direct renin inhibitors is currently under investigation while that based on an aldosterone blocker with any of the previous three drugs requires more evidence beyond heart failure. In this review, we revisited potential advantages of dual blockade of renin-angiotensin-aldosterone system in arterial hypertension and diabetes.

Lithium attenuated the behavioral despair induced by acute neurogenic stress through blockade of opioid receptors in mice.

PubMed

Khaloo, Pegah; Sadeghi, Banafshe; Ostadhadi, Sattar; Norouzi-Javidan, Abbas; Haj-Mirzaian, Arya; Zolfagharie, Samira; Dehpour, Ahmad-Reza

2016-10-01

Major depressive disorder is disease with high rate of morbidity and mortality. Stressful events lead to depression and they can be used as a model of depression in rodents. In this study we aimed to investigate whether lithium modifies the stressed-induced depression through blockade of opioid receptors in mice. We used foot shock stress as stressor and forced swimming test (FST), tail suspension test (TST) and open field test (OFT) to evaluation the behavioral responses in mice. We also used naltrexone hydrochloride (as opioid receptor antagonist), and morphine (as opioid receptor agonist). Our results displayed that foot-shock stress significantly increased the immobility time in TST and FST but it could not change the locomotor behavior in OFT. When we combined the low concentrations of lithium and naltrexone a significant reduction in immobility time was seen in the FST and TST in comparison with control foot-shock stressed group administered saline only. Despite the fact that our data showed low concentrations of lithium, when administered independently did not significantly affect the immobility time. Also our data indicated that concurrent administration of lithium and naltrexone had no effect on open field test. Further we demonstrated that simultaneous administration of morphine and lithium reverses the antidepressant like effect of active doses of lithium. Our data acclaimed that we lithium can augment stressed-induced depression and opioid pathways are involved in this action. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Blockade of NMDA receptors decreased spinal microglia activation in bee venom induced acute inflammatory pain in rats.

PubMed

Li, Li; Wu, Yongfang; Bai, Zhifeng; Hu, Yuyan; Li, Wenbin

2017-03-01

Microglial cells in spinal dorsal horn can be activated by nociceptive stimuli and the activated microglial cells release various cytokines enhancing the nociceptive transmission. However, the mechanisms underlying the activation of spinal microglia during nociceptive stimuli have not been well understood. In order to define the role of NMDA receptors in the activation of spinal microglia during nociceptive stimuli, the present study was undertaken to investigate the effect of blockade of NMDA receptors on the spinal microglial activation induced by acute peripheral inflammatory pain in rats. The acute inflammatory pain was induced by subcutaneous bee venom injection to the plantar surface of hind paw of rats. Spontaneous pain behavior, thermal withdrawal latency and mechanical withdrawal threshold were rated. The expression of specific microglia marker CD11b/c was assayed by immunohistochemistry and western blot. After bee venom treatment, it was found that rats produced a monophasic nociception characterized by constantly lifting and licking the injected hind paws, decreased thermal withdrawal latency and mechanical withdrawal threshold; immunohistochemistry displayed microglia with enlarged cell bodies, thickened, extended cellular processes with few ramifications, small spines, and intensive immunostaining; western blot showed upregulated expression level of CD11b/c within the period of hyperalgesia. Prior intrathecal injection of MK-801, a selective antagonist of NMDA receptors, attenuated the pain behaviors and suppressed up-regulation of CD11b/c induced by bee venom. It can be concluded that NMDA receptors take part in the mediation of spinal microglia activation in bee venom induced peripheral inflammatory pain and hyperalgesia in rats.

The Role of 5-HT2A, 5-HT2C and mGlu2 Receptors in the Behavioral Effects of Tryptamine Hallucinogens N,N-Dimethyltryptamine and N,N-Diisopropyltryptamine in Rats and Mice

PubMed Central

Carbonaro, Theresa M.; Eshleman, Amy J.; Forster, Michael J.; Cheng, Kejun; Rice, Kenner C.; Gatch, Michael B.

2014-01-01

Rationale: Serotonin 5-HT2A and 5-HT2C receptors are thought to be the primary pharmacological mechanisms for serotonin-mediated hallucinogenic drugs, but recently there has been interest in metabotropic glutamate (mGluR2) receptors as contributors to the mechanism of hallucinogens. Objective: The present study assesses the role of these 5-HT and glutamate receptors as molecular targets for two tryptamine hallucinogens, N,N-dimethyltryptamine (DMT) and N,N-diisopropyltryptamine (DiPT). Methods: Drug discrimination, head twitch and radioligand binding assays were used. A 5-HT2AR inverse agonist (MDL100907), 5-HT2CR antagonist (SB242084) and mGluR2/3 agonist (LY379268) were tested for their ability to attenuate the discriminative stimulus effects of DMT and DiPT; an mGluR2/3 antagonist (LY341495) was tested for potentiation. MDL100907 was used to attenuate head twitches induced by DMT and DiPT. Radioligand binding studies and inosital-1-phosphate (IP-1) accumulation were performed at the 5-HT2CR for DiPT. Results: MDL100907 fully blocked the discriminative stimulus effects of DMT, but only partially blocked DiPT. SB242084 partially attenuated the discriminative stimulus effects of DiPT, but produced minimal attenuation of DMT’s effects. LY379268 produced potent, but only partial blockade of the discriminative stimulus effects of DMT. LY341495 facilitated DMT- and DiPT-like effects. Both compounds elicited head twitches (DiPT>DMT) which were blocked by MDL1000907. DiPT was a low potency full agonist at 5-HT2CR in vitro. Conclusions: The 5-HT2AR likely plays a major role in mediating the effects of both compounds. 5-HT2C and mGluR2 receptors likely modulate the discriminative stimulus effects of both compounds to some degree. PMID:24985890

The role of 5-HT2A, 5-HT 2C and mGlu2 receptors in the behavioral effects of tryptamine hallucinogens N,N-dimethyltryptamine and N,N-diisopropyltryptamine in rats and mice.

PubMed

Carbonaro, Theresa M; Eshleman, Amy J; Forster, Michael J; Cheng, Kejun; Rice, Kenner C; Gatch, Michael B

2015-01-01

Serotonin 5-HT2A and 5-HT2C receptors are thought to be the primary pharmacological mechanisms for serotonin-mediated hallucinogenic drugs, but recently there has been interest in metabotropic glutamate (mGluR2) receptors as contributors to the mechanism of hallucinogens. The present study assesses the role of these 5-HT and glutamate receptors as molecular targets for two tryptamine hallucinogens, N,N-dimethyltryptamine (DMT) and N,N-diisopropyltryptamine (DiPT). Drug discrimination, head twitch, and radioligand binding assays were used. A 5-HT2AR inverse agonist (MDL100907), 5-HT2CR antagonist (SB242084), and mGluR2/3 agonist (LY379268) were tested for their ability to attenuate the discriminative stimulus effects of DMT and DiPT; an mGluR2/3 antagonist (LY341495) was tested for potentiation. MDL100907 was used to attenuate head twitches induced by DMT and DiPT. Radioligand binding studies and inosital-1-phosphate (IP-1) accumulation were performed at the 5-HT2CR for DiPT. MDL100907 fully blocked the discriminative stimulus effects of DMT, but only partially blocked DiPT. SB242084 partially attenuated the discriminative stimulus effects of DiPT, but produced minimal attenuation of DMT's effects. LY379268 produced potent, but only partial blockade of the discriminative stimulus effects of DMT. LY341495 facilitated DMT- and DiPT-like effects. Both compounds elicited head twitches (DiPT>DMT) which were blocked by MDL1000907. DiPT was a low-potency full agonist at 5-HT2CR in vitro. The 5-HT2AR likely plays a major role in mediating the effects of both compounds. 5-HT2C and mGluR2 receptors likely modulate the discriminative stimulus effects of both compounds to some degree.

Intra-accumbal blockade of endocannabinoid CB1 receptors impairs learning but not retention of conditioned relief.

PubMed

Bergado Acosta, Jorge R; Schneider, Miriam; Fendt, Markus

2017-10-01

Humans and animals are able to associate an environmental cue with the feeling of relief from an aversive event, a phenomenon called relief learning. Relief from an aversive event is rewarding and a relief-associated cue later induces an attenuation of the startle magnitude or approach behavior. Previous studies demonstrated that the nucleus accumbens is essential for relief learning. Here, we asked whether accumbal cannabinoid type 1 (CB1) receptors are involved in relief learning. In rats, we injected the CB1 receptor antagonist/inverse agonist SR141716A (rimonabant) directly into the nucleus accumbens at different time points during a relief learning experiment. SR141716A injections immediately before the conditioning inhibited relief learning. However, SR141716A injected immediately before the retention test was not effective when conditioning was without treatment. These findings indicate that accumbal CB1 receptors play an important role in the plasticity processes underlying relief learning. Copyright © 2017 Elsevier Inc. All rights reserved.

Low Dose Naltrexone in the Treatment of Fibromyalgia.

PubMed

Metyas, Samy K; Yeter, Karen; Solyman, John; Arkfeld, Daniel

2017-03-21

Fibromyalgia is a chronic pain disorder characterized by diffuse musculoskeletal pain, fatigue, sleep disturbance and cognitive impairment. A significant number of fibromyalgia patients do not respond adequately to the current drugs (pregabalin, milnacipran, duloxetine) approved for fibromyalgia treatment by the Food and Drug Administration (FDA). Thus, there is still a need for adjunctive therapies. Naltrexone is an opioid receptor antagonist used to treat alcohol and opioid dependence. It is hypothesized that low dose naltrexone causes transient blockade of opioid receptors centrally resulting in a rebound of endorphin function which may attenuate pain in fibromyalgia. Treatment with low dose naltrexone may be an effective, highly tolerable and inexpensive treatment for fibromyalgia. Further controlled trials are needed. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Combination CTLA-4 Blockade and 4-1BB Activation Enhances Tumor Rejection by Increasing T-Cell Infiltration, Proliferation, and Cytokine Production

PubMed Central

Curran, Michael A.; Kim, Myoungjoo; Montalvo, Welby; Al-Shamkhani, Aymen; Allison, James P.

2011-01-01

Background The co-inhibitory receptor Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4) attenuates immune responses and prevent autoimmunity, however, tumors exploit this pathway to evade the host T-cell response. The T-cell co-stimulatory receptor 4-1BB is transiently upregulated on T-cells following activation and increases their proliferation and inflammatory cytokine production when engaged. Antibodies which block CTLA-4 or which activate 4-1BB can promote the rejection of some murine tumors, but fail to cure poorly immunogenic tumors like B16 melanoma as single agents. Methodology/Principal Findings We find that combining αCTLA-4 and α4-1BB antibodies in the context of a Flt3-ligand, but not a GM-CSF, based B16 melanoma vaccine promoted synergistic levels of tumor rejection. 4-1BB activation elicited strong infiltration of CD8+ T-cells into the tumor and drove the proliferation of these cells, while CTLA-4 blockade did the same for CD4+ effector T-cells. Anti-4-1BB also depressed regulatory T-cell infiltration of tumors. 4-1BB activation strongly stimulated inflammatory cytokine production in the vaccine and tumor draining lymph nodes and in the tumor itself. The addition of CTLA-4 blockade further increased IFN-γ production from CD4+ effector T-cells in the vaccine draining node and the tumor. Anti 4-1BB treatment, with or without CTLA-4 blockade, induced approximately 75% of CD8+ and 45% of CD4+ effector T-cells in the tumor to express the killer cell lectin-like receptor G1 (KLRG1). Tumors treated with combination antibody therapy showed 1.7-fold greater infiltration by these KLRG1+CD4+ effector T-cells than did those treated with α4-1BB alone. Conclusions/Significance This study shows that combining T-cell co-inhibitory blockade with αCTLA-4 and active co-stimulation with α4-1BB promotes rejection of B16 melanoma in the context of a suitable vaccine. In addition, we identify KLRG1 as a useful marker for monitoring the anti-tumor immune response elicited by this therapy. These findings should aid in the design of future trials for the immunotherapy of melanoma. PMID:21559358

Glutamate Receptors in the Central Nucleus of the Amygdala Mediate Cisplatin-Induced Malaise and Energy Balance Dysregulation through Direct Hindbrain Projections

PubMed Central

Alhadeff, Amber L.; Holland, Ruby A.; Nelson, Alexandra; Grill, Harvey J.

2015-01-01

Cisplatin chemotherapy is used commonly to treat a variety of cancers despite severe side effects such as nausea, vomiting, and anorexia that compromise quality of life and limit treatment adherence. The neural mechanisms mediating these side effects remain elusive despite decades of clinical use. Recent data highlight the dorsal vagal complex (DVC), lateral parabrachial nucleus (lPBN), and central nucleus of the amygdala (CeA) as potential sites of action in mediating the side effects of cisplatin. Here, results from immunohistochemical studies in rats identified a population of cisplatin-activated DVC neurons that project to the lPBN and a population of cisplatin-activated lPBN calcitonin gene-related peptide (CGRP, a marker for glutamatergic neurons in the lPBN) neurons that project to the CeA, outlining a neuroanatomical circuit that is activated by cisplatin. CeA gene expressions of AMPA and NMDA glutamate receptor subunits were markedly increased after cisplatin treatment, suggesting that CeA glutamate receptor signaling plays a role in mediating cisplatin side effects. Consistent with gene expression results, behavioral/pharmacological data showed that CeA AMPA/kainate receptor blockade attenuates cisplatin-induced pica (a proxy for nausea/behavioral malaise in nonvomiting laboratory rodents) and that CeA NMDA receptor blockade attenuates cisplatin-induced anorexia and body weight loss in addition to pica, demonstrating that glutamate receptor signaling in the CeA is critical for the energy balance dysregulation caused by cisplatin treatment. Together, these data highlight a novel circuit and CGRP/glutamatergic mechanism through which cisplatin-induced malaise and energy balance dysregulation are mediated. SIGNIFICANCE STATEMENT To treat cancer effectively, patients must follow prescribed chemotherapy treatments without interruption, yet most cancer treatments produce side effects that devastate quality of life (e.g., nausea, vomiting, anorexia, weight loss). Although hundreds of thousands of patients undergo chemotherapies each year, the neural mechanisms mediating their side effects are unknown. The current data outline a neural circuit activated by cisplatin chemotherapy and demonstrate that glutamate signaling in the amygdala, arising from hindbrain projections, is required for the full expression of cisplatin-induced malaise, anorexia, and body weight loss. Together, these data help to characterize the neural circuits and neurotransmitters mediating chemotherapy-induced energy balance dysregulation, which will ultimately provide an opportunity for the development of well tolerated cancer and anti-emetic treatments. PMID:26245970

Patch clamp reveals powerful blockade of the mitochondrial permeability transition pore by the D2-receptor agonist pramipexole.

PubMed

Sayeed, Iqbal; Parvez, Suhel; Winkler-Stuck, Kirstin; Seitz, Gordon; Trieu, Isabelle; Wallesch, Claus-Werner; Schönfeld, Peter; Siemen, Detlef

2006-03-01

The dopamine-D2-agonist pramipexole (PPX) was tested for blocking mitochondrial permeability transition (PT) in order to give a possible explanation for its neuroprotective effect seen in PPX-treated Parkinson's disease patients. Patch-clamp techniques for studying single-channel currents in the inner mitochondrial membrane and large-amplitude swelling of energized mitochondria were used to study PPX action on the permeability transition pore (PTP), a key player in the mitochondrial route of the apoptotic cascade. Identity of the PTP was proven by measuring the concentration-response relation for cyclosporin A-blockade (IC50=26 nM). PPX inhibits the PTP reversibly with an IC50 of 500 nM, which is close to the values determined earlier as plasma concentrations after PPX medication in patients. Interaction of PPX with the PTP is further supported by demonstrating that it abolished Ca2+-triggered swelling in functionally intact mitochondria. Blockade of the PTP by PPX was attenuated by increasing concentrations of inorganic phosphate and by acidification. We suggest that PPX could exert part of its neuroprotective effect by inhibition of the PTP and thus, probably, blocking of the mitochondrial pathway of the apoptosis cascade.

Impaired peripheral vasodilation during graded systemic hypoxia in healthy older adults: role of the sympathoadrenal system

PubMed Central

Richards, Jennifer C.; Crecelius, Anne R.; Larson, Dennis G.; Luckasen, Gary J.

2017-01-01

Systemic hypoxia is a physiological and pathophysiological stress that activates the sympathoadrenal system and, in young adults, leads to peripheral vasodilation. We tested the hypothesis that peripheral vasodilation to graded systemic hypoxia is impaired in older healthy adults and that this age-associated impairment is due to attenuated β-adrenergic mediated vasodilation and elevated α-adrenergic vasoconstriction. Forearm blood flow was measured (Doppler ultrasound), and vascular conductance (FVC) was calculated in 12 young (24 ± 1 yr) and 10 older (63 ± 2 yr) adults to determine the local dilatory responses to graded hypoxia (90, 85, and 80% O2 saturations) in control conditions, following local intra-arterial blockade of β-receptors (propranolol), and combined blockade of α- and β-receptors (phentolamine + propranolol). Under control conditions, older adults exhibited impaired vasodilation to hypoxia compared with young participants at all levels of hypoxia (peak ΔFVC at 80% SpO2 = 4 ± 6 vs. 35 ± 8%; P < 0.01). During β-blockade, older adults actively constricted at 85 and 80% SpO2 (peak ΔFVC at 80% SpO2 = −13 ± 6%; P < 0.05 vs. control), whereas the response in the young was not significantly impacted (peak ΔFVC = 28 ± 8%). Combined α- and β-blockade increased the dilatory response to hypoxia in young adults; however, older adults failed to significantly vasodilate (peak ΔFVC at 80% SpO2= 12 ± 11% vs. 58 ± 11%; P < 0.05). Our findings indicate that peripheral vasodilation to graded systemic hypoxia is significantly impaired in older adults, which cannot be fully explained by altered sympathoadrenal control of vascular tone. Thus, the impairment in hypoxic vasodilation is likely due to attenuated local vasodilatory and/or augmented vasoconstrictor signaling with age. NEW & NOTEWORTHY We found that the lack of peripheral vasodilation during graded systemic hypoxia with aging is not mediated by the sympathoadrenal system, strongly implicating local vascular control mechanisms in this impairment. Understanding these mechanisms may lead to therapeutic advances for improving tissue blood flow and oxygen delivery in aging and disease. PMID:28159810

Kappa Opioid Receptors Mediate Heterosynaptic Suppression of Hippocampal Inputs in the Rat Ventral Striatum

PubMed Central

2017-01-01

Kappa opioid receptors (KORs) are highly enriched within the ventral striatum (VS) and are thought to modulate striatal neurotransmission. This includes presynaptic inhibition of local glutamatergic release from excitatory inputs to the VS. However, it is not known which inputs drive this modulation and what impact they have on the local circuit dynamics within the VS. Individual medium spiny neurons (MSNs) within the VS serve as a site of convergence for glutamatergic inputs arising from the PFC and limbic regions, such as the hippocampus (HP). Recent data suggest that competition can arise between these inputs with robust cortical activation leading to a reduction in ongoing HP-evoked MSN responses. Here, we investigated the contribution of KOR signaling in PFC-driven heterosynaptic suppression of HP inputs onto MSNs using whole-cell patch-clamp recordings in slices from adult rats. Optogenetically evoked HP EPSPs were greatly attenuated after a short latency (50 ms) following burst-like PFC electrical stimulation, and the magnitude of this suppression was partially reversed following blockade of GABAARs (GABA Type A receptors), but not GABABRs (GABA Type B receptors). A similar reduction in suppression was observed in the presence of the KOR antagonist, norBNI. Combined blockade of local GABAARs and KORs resulted in complete blockade of PFC-induced heterosynaptic suppression of less salient HP inputs. These findings highlight a mechanism by which strong, transient PFC activity can take precedence over other excitatory inputs to the VS. SIGNIFICANCE STATEMENT Emerging evidence suggests that kappa opioid receptor (KOR) activation can selectively modulate striatal glutamatergic inputs onto medium spiny neurons (MSNs). In this study, we found that robust cortical stimulation leads to a reduction in ongoing hippocampal-evoked MSNs responses through the combined recruitment of local inhibitory mechanisms and activation of presynaptic KORs in the ventral striatum (VS). These processes are likely to facilitate the efficient transfer of cortical information through the VS during critical decision making by dampening competing information from less salient excitatory inputs. These data provide a novel mechanism through which VS information processing could influence decision making, a function thought to occur primarily in the PFC. PMID:28642282

Glucocorticoid receptors in the prefrontal cortex regulate stress-evoked dopamine efflux and aspects of executive function.

PubMed

Butts, Kelly A; Weinberg, Joanne; Young, Allan H; Phillips, Anthony G

2011-11-08

Enhanced dopamine efflux in the prefrontal cortex is a well-documented response to acute stress. However, the underlying mechanism(s) for this response is unknown. Using in vivo microdialysis, we demonstrate that blocking glucocorticoid receptors locally within the rat prefrontal cortex results in a reduction in stress-evoked dopamine efflux. In contrast, blocking glucocorticoid receptors in the ventral tegmental area did not affect stress-evoked dopamine efflux in the prefrontal cortex. Additionally, local administration of corticosterone into the prefrontal cortex increased prefrontal dopamine efflux. The functional impact of enhanced dopamine efflux evoked by acute stress was demonstrated using a cognitive task dependent on the prefrontal cortex and sensitive to impairment in working memory. Notably, stress-induced impairments in cognition were attenuated by blockade of glucocorticoid receptors in the prefrontal cortex. Taken together, these data demonstrate that glucocorticoids act locally within the prefrontal cortex to modulate mesocortical dopamine efflux leading to the cognitive impairments observed during acute stress.

Anteroventral Third Ventricle Lesions Attenuate Pressor Responses to Serotonin in Anesthetized Rats

NASA Technical Reports Server (NTRS)

Muntzel, Martin S.; Lewis, Stephen J.; Johnson, Alan Kim

1996-01-01

When administered intravenously, serotonin (5-hydroxytryptamine; 5-HT) evokes a triphasic blood pressure response, consisting of the Bezold-Jarisch-associated depressor response, a pressor action, and long-lasting depressor response. Because the pressor response may, in part, be caused by central nervous system (CNS) activation by 5-HT, we predicted that destruction of the anteroventral third ventricle (AV3V) region, an area rich in 5-HT receptors, would attenuate increases in blood pressure to intravenous 5-HT. In anesthetized sham-lesioned and AV3V-lesioned Sprague-Dawley rats. we measured mean arterial pressure (MAP), heart rate (HR), and lumbar sympathetic nerve activity (SNA) to increasing bolus doses of intravenous 5-HT (1, 2.5, 5, 10, 25 microg/kg), before and after blockade of bradycardia using methylatropine (200 microg/kg). In all rats, bolus injections of 5-HT elicited bradycardia accompanied by a fall in lumbar SNA and an initial hypotension followed by a pressor response and a longer lasting hypotensive response. The bradycardia, reduction in lumbar SNA, and both depressor responses were equivalent in sham-lesioned and AV3V-lesioned groups. Importantly, AV3V lesions attenuated pressor responses to increasing doses of 5-HT (3 +/- 1, 6 +/- 4, 6 +/- 4, 17 +/- 4, 35 +/- 3 mmHg) compared to sham-lesioned controls (6 +/- 3, 16 +/- 7, 33 +/- 5, 54 +/- 4, 51 +/- 6 mmHg; P < 0.0001). This attenuation was conserved following blockade of bradycardia with methylatropine (P < 0.01). In summary, pressor responses to intravenous 5-HT are diminished by AV3V lesions. These data indicate that the pressor component of the blood pressure response to intravenous 5-HT is partly dependent upon interaction with the CNS.

Activation of NMDA receptors reduces metabotropic glutamate receptor-induced long-term depression in the nucleus accumbens via a CaMKII-dependent mechanism.

PubMed

Huang, Chiung-Chun; Hsu, Kuei-Sen

2012-12-01

Glutamate is the major excitatory neurotransmitter in the brain and exerts its actions through two distinct types of receptors, ionotropic and metabotropic glutamate receptors (mGluR). Although functional interplay between ionotropic N-methyl-d-aspartate receptors (NMDAR) and mGluR has been convincingly demonstrated in native and recombinant systems, the mechanism by which NMDAR activation leads to modulation of mGluR function has yet to be elucidated. Using whole-cell patch-clamp recordings in mouse nucleus accumbens (NAc) slices, we found that tetanic stimulation (TS) of excitatory afferents with a naturally occurring frequency (10 min at 13 Hz) reliably induces a mGluR1/5-dependent long-term depression (mGluR1/5-LTD) of excitatory synaptic transmission. Blockade of NMDAR during but not after TS showed enhanced mGluR1/5-LTD induction, which is associated with its antagonism of TS-induced calcium/calmodulin-dependent protein kinase II (CaMKII) activation. The ability of NMDAR antagonists to promote mGluR1/5-LTD induction was mimicked by a selective CaMKII inhibitor KN-62. However, the induction of mGluR1/5-LTD by bath-applied agonist (S)-3,5-dihydrophenylglycine was not affected by NMDAR blockade. We also observed that NMDAR or CaMKII blockade during TS significantly blunted TS-induced increased serine/threonine phosphorylation of the scaffold protein Homer1b/c and resulted in an increased interaction of mGluR5 with the Homer1b/c. These results indicate that synaptically released glutamate during TS of excitatory afferents can activate both NMDAR and mGluR1/5 in NAc neurons concomitantly and that activation of NMDAR may stimulate CaMKII-mediated phosphorylation of Homer1b/c and impair the interaction between mGluR5 and Homer1b/c, thereby attenuating mGluR1/5-LTD induction. This study provides a novel molecular mechanism by which NMDAR could regulate mGluR5 function. Copyright © 2012 Elsevier Ltd. All rights reserved.

Role of GABAA receptors in dorsal raphe nucleus in stress-induced reinstatement of morphine-conditioned place preference in rats.

PubMed

Li, Chen; Staub, Daniel R; Kirby, Lynn G

2013-12-01

The serotonin (5-hydroxytryptamine, 5-HT) system plays an important role in stress-related psychiatric disorders and substance abuse. Our data indicate that stress inhibits the dorsal raphe nucleus (DRN)-5-HT system via stimulation of GABA synaptic activity by the stress neurohormone corticotropin-releasing factor and, more recently, that morphine history sensitizes DRN-5-HT neurons to GABAergic inhibitory effects of stress. We tested the hypothesis that DRN GABAA receptors contribute to stress-induced reinstatement of morphine-conditioned place preference (CPP). First, we tested if activation of GABAA receptors in the DRN would reinstate morphine CPP. Second, we tested if blockade of GABAA receptors in the DRN would attenuate swim stress-induced reinstatement of morphine CPP. CPP was induced by morphine (5 mg/kg) in a 4-day conditioning phase followed by a conditioning test. Upon acquiring conditioning criteria, subjects underwent 4 days of extinction training followed by an extinction test. Upon acquiring extinction criteria, animals underwent a reinstatement test. For the first experiment, the GABAA receptor agonist muscimol (50 ng) or vehicle was injected into the DRN prior to the reinstatement test. For the second experiment, the GABAA receptor antagonist bicuculline (75 ng) or vehicle was injected into the DRN prior to a forced swim stress, and then, animals were tested for reinstatement of CPP. Intraraphe injection of muscimol reinstated morphine CPP, while intraraphe injection of bicuculline attenuated swim stress-induced reinstatement. These data provide evidence that GABAA receptor-mediated inhibition of the serotonergic DRN contributes to stress-induced reinstatement of morphine CPP.

Blockade of Endocannabinoid Hydrolytic Enzymes Attenuates Precipitated Opioid Withdrawal Symptoms in MiceS⃞

PubMed Central

Ramesh, Divya; Ross, Gracious R.; Schlosburg, Joel E.; Owens, Robert A.; Abdullah, Rehab A.; Kinsey, Steven G.; Long, Jonathan Z.; Nomura, Daniel K.; Sim-Selley, Laura J.; Cravatt, Benjamin F.; Akbarali, Hamid I.

2011-01-01

Δ9-Tetrahydrocannbinol (THC), the primary active constituent of Cannabis sativa, has long been known to reduce opioid withdrawal symptoms. Although THC produces most of its pharmacological actions through the activation of CB1 and CB2 cannabinoid receptors, the role these receptors play in reducing the variety of opioid withdrawal symptoms remains unknown. The endogenous cannabinoids, N-arachidonoylethanolamine (anandamide; AEA) and 2-arachidonylglycerol (2-AG), activate both cannabinoid receptors but are rapidly metabolized by fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), respectively. The objective of this study was to test whether increasing AEA or 2-AG, via inhibition of their respective hydrolytic enzymes, reduces naloxone-precipitated morphine withdrawal symptoms in in vivo and in vitro models of opioid dependence. Morphine-dependent mice challenged with naloxone reliably displayed a profound withdrawal syndrome, consisting of jumping, paw tremors, diarrhea, and weight loss. THC and the MAGL inhibitor 4-nitrophenyl 4-(dibenzo[d][1,3]dioxol-5-yl(hydroxy)methyl)piperidine-1-carboxylate (JZL184) dose dependently reduced the intensity of most measures through the activation of CB1 receptors. JZL184 also attenuated spontaneous withdrawal signs in morphine-dependent mice. The FAAH inhibitor N-(pyridin-3-yl)-4-(3-(5-(trifluoromethyl)pyridin-2-yloxy)benzyl)-piperdine-1-carboxamide (PF-3845) reduced the intensity of naloxone-precipitated jumps and paw flutters through the activation of CB1 receptors but did not ameliorate incidence of diarrhea or weight loss. In the final series of experiments, we investigated whether JZL184 or PF-3845 would attenuate naloxone-precipitated contractions in morphine-dependent ilea. Both enzyme inhibitors attenuated the intensity of naloxone-induced contractions, although this model does not account mechanistically for the autonomic withdrawal responses (i.e., diarrhea) observed in vivo. These results indicate that endocannabinoid catabolic enzymes are promising targets to treat opioid dependence. PMID:21719468

D-1 and D-2 receptor blockade have additive cataleptic effects in mice, but receptor effects may interact in opposite ways.

PubMed

Klemm, W R; Block, H

1988-02-01

The dopaminergic role of D-1 and D-2 receptors in catalepsy was evaluated using drugs with preferential receptor affinities. The D-1 antagonist, SCH 23390, caused distinct catalepsy in mice at 1, 2, and 10 mg/kg, IP, but not at two lower doses. The selective D-1 blocker, molindone, also caused catalepsy at 5 and 10 mg/kg; and blockade of both receptor types produced additive cataleptogenic effects. Apomorphine (4 mg/kg), which is an agonist for both receptors, potentiated SCH 23390-induced catalepsy much more than it did the catalepsy induced by molindone; the potentiation was produced by higher, not lower, doses of apomorphine. To determine if the apomorphine potentiation was mediated by D-1 or D-2 receptors, we tested selective agonists in mice that were concurrently injected with selective blockers. SCH 23390-induced catalepsy was potentiated by a large dose of the D-2 agonist, bromocriptine. The catalepsy of D-2 blockade with molindone was not potentiated by the D-1 agonist, SKF 38393, which slightly disrupted the catalepsy of D-2 blockade. We conclude that catalepsy is not a simple D-2 blockade phenomenon and that preferential antagonism of either receptor type can cause catalepsy. Catalepsy is most profound when both receptor types are blocked. Dopamine agonists, in large concentrations, are known to promote movements, and thus it is not surprising that they tend to disrupt catalepsy.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of pan neurotrophin receptor p75 attenuates diesel particulate-induced enhancement of allergic airway responses in C57/B16J mice.

PubMed

Farraj, Aimen K; Haykal-Coates, Najwa; Ledbetter, Allen D; Evansky, Paul A; Gavett, Stephen H

2006-06-01

Recent investigations have linked neurotrophins, including nerve growth factor (NGF), neurotrophin-3 (NT-3), and brain-derived neurotrophic factor (BDNF), to allergic airways diseases. Antibody blockade of NGF attenuates airway resistance in allergic mice. Diesel exhaust particle (DEP) exposure has been linked to asthma exacerbation in many cities with vehicular traffic congestion. We tested the hypothesis that DEP-induced enhancement of the hallmark features of allergic airway disease in a murine model is dependent on the function of the pan neurotrophin receptor p75. Ovalbumin (OVA)-sensitized C57B1/6J mice were intranasally instilled with an antibody against the p75 receptor or saline alone 1 h before OVA challenge. The mice were then exposed nose-only to the PM2.5 fraction of SRM2975 DEP or air alone for 5 h beginning 1 h after OVA challenge. Two days later, air-exposed OVA-allergic mice developed a small but insignificant increase in methacholine-induced airflow obstruction relative to air-exposed, vehicle-sensitized mice. DEP-exposed OVA-allergic mice had a significantly greater degree of airway obstruction than all other groups. Instillation of anti-p75 significantly attenuated the DEP-induced increase in airway obstruction in OVA-allergic mice to levels similar to non-sensitized mice. The DEP-induced exacerbation of allergic airway responses may, in part, be mediated by neurotrophins.

The adenosine A2A antagonist MSX-3 reverses the effort-related effects of dopamine blockade: differential interaction with D1 and D2 family antagonists.

PubMed

Worden, Lila T; Shahriari, Mona; Farrar, Andrew M; Sink, Kelly S; Hockemeyer, Jörg; Müller, Christa E; Salamone, John D

2009-04-01

Brain dopamine (DA) participates in the modulation of instrumental behavior, including aspects of behavioral activation and effort-related choice behavior. Rats with impaired DA transmission reallocate their behavior away from food-seeking behaviors that have high response requirements, and instead select less effortful alternatives. Although accumbens DA is considered a critical component of the brain circuitry regulating effort-related choice behavior, emerging evidence demonstrates a role for adenosine A(2A) receptors. Adenosine A(2A) receptor antagonism has been shown to reverse the effects of DA antagonism. The present experiments were conducted to determine if this effect was dependent upon the subtype of DA receptor that was antagonized to produce the changes in effort-related choice. The adenosine A(2A) receptor antagonist MSX-3 (0.5-2.0 mg/kg IP) was assessed for its ability to reverse the effects of the D1 family antagonist SCH39166 (ecopipam; 0.2 mg/kg IP) and the D2 family antagonist eticlopride (0.08 mg/kg IP), using a concurrent lever pressing/chow feeding procedure. MSX-3 produced a substantial dose-related reversal of the effects of eticlopride on lever pressing and chow intake. At the highest dose of MSX-3, there was a complete reversal of the effects of eticlopride on lever pressing. In contrast, MSX-3 produced only a minimal attenuation of the effects of SCH39166, as measured by regression and effect size analyses. The greater ability of MSX-3 to reverse the effects of D2 vs. D1 blockade may be related to the colocalization of D2 and adenosine A(2A) receptors on the same population of striatal neurons.

5-HT2A receptors control body temperature in mice during LPS-induced inflammation via regulation of NO production.

PubMed

Voronova, Irina P; Khramova, Galina M; Kulikova, Elizabeth A; Petrovskii, Dmitrii V; Bazovkina, Daria V; Kulikov, Alexander V

2016-01-01

G protein-coupled 5-HT2A receptors are involved in the regulation of numerous normal and pathological physiological functions. At the same time, its involvement in the regulation of body temperature (Tb) in normal conditions is obscure. Here we study the effect of the 5-HT2A receptor activation or blockade on Tb in sick animals. The experiments were carried out on adult C57BL/6 mouse males. Systemic inflammation and sickness were produced by lipopolysaccharide (LPS, 0.1mg/kg, ip), while the 5-HT2A receptor was stimulated or blocked through the administration of the receptor agonist DOI or antagonist ketanserin (1mg/kg), respectively. LPS, DOI or ketanserin alone produced no effect on Tb. However, administration of LPS together with a peripheral or central ketanserin injection reduced Tb (32.2°C). Ketanserin reversed the LPS-induced expression of inducible NO synthase in the brain. Consequently, an involvement of NO in the mechanism of the hypothermic effect of ketanserin in sick mice was hypothesized. Administration of LPS together with NO synthase inhibitor, l-nitro-arginine methyl ester (60mg/kg, ip) resulted in deep (28.5°C) and prolonged (8h) hypothermia, while administration of l-nitro-arginine methyl ester alone produced no effect on Tb. Thus, 5-HT2A receptors play a key role in Tb control in sick mice. Blockade of this GPCR produces hypothermia in mice with systemic inflammation via attenuation of LPS-induced NO production. These results indicate an unexpected role of 5-HT2A receptors in inflammation and NO production and have a considerable biological impact on understanding the mechanism of animal adaptation to pathogens and parasites. Moreover, adverse side effects of 5-HT2A receptor antagonists in patients with inflammation may be expected. Copyright © 2015 Elsevier Ltd. All rights reserved.

Moderate dietary sodium restriction added to angiotensin converting enzyme inhibition compared with dual blockade in lowering proteinuria and blood pressure: randomised controlled trial.

PubMed

Slagman, Maartje C J; Waanders, Femke; Hemmelder, Marc H; Woittiez, Arend-Jan; Janssen, Wilbert M T; Lambers Heerspink, Hiddo J; Navis, Gerjan; Laverman, Gozewijn D

2011-07-26

To compare the effects on proteinuria and blood pressure of addition of dietary sodium restriction or angiotensin receptor blockade at maximum dose, or their combination, in patients with non-diabetic nephropathy receiving background treatment with angiotensin converting enzyme (ACE) inhibition at maximum dose. Multicentre crossover randomised controlled trial. Outpatient clinics in the Netherlands. 52 patients with non-diabetic nephropathy. All patients were treated during four 6 week periods, in random order, with angiotensin receptor blockade (valsartan 320 mg/day) or placebo, each combined with, consecutively, a low sodium diet (target 50 mmol Na(+)/day) and a regular sodium diet (target 200 mmol Na(+)/day), with a background of ACE inhibition (lisinopril 40 mg/day) during the entire study. The drug interventions were double blind; the dietary interventions were open label. The primary outcome measure was proteinuria; the secondary outcome measure was blood pressure. Mean urinary sodium excretion, a measure of dietary sodium intake, was 106 (SE 5) mmol Na(+)/day during a low sodium diet and 184 (6) mmol Na(+)/day during a regular sodium diet (P<0.001). Geometric mean residual proteinuria was 1.68 (95% confidence interval 1.31 to 2.14) g/day during ACE inhibition plus a regular sodium diet. Addition of angiotensin receptor blockade to ACE inhibition reduced proteinuria to 1.44 (1.07 to 1.93) g/day (P=0.003), addition of a low sodium diet reduced it to 0.85 (0.66 to 1.10) g/day (P<0.001), and addition of angiotensin receptor blockade plus a low sodium diet reduced it to 0.67 (0.50 to 0.91) g/day (P<0.001). The reduction of proteinuria by the addition of a low sodium diet to ACE inhibition (51%, 95% confidence interval 43% to 58%) was significantly larger (P<0.001) than the reduction of proteinuria by the addition of angiotensin receptor blockade to ACE inhibition (21%, (8% to 32%) and was comparable (P=0.009, not significant after Bonferroni correction) to the reduction of proteinuria by the addition of both angiotensin receptor blockade and a low sodium diet to ACE inhibition (62%, 53% to 70%). Mean systolic blood pressure was 134 (3) mm Hg during ACE inhibition plus a regular sodium diet. Mean systolic blood pressure was not significantly altered by the addition of angiotensin receptor blockade (131 (3) mm Hg; P=0.12) but was reduced by the addition of a low sodium diet (123 (2) mm Hg; P<0.001) and angiotensin receptor blockade plus a low sodium diet (121 (3) mm Hg; P<0.001) to ACE inhibition. The reduction of systolic blood pressure by the addition of a low sodium diet (7% (SE 1%)) was significantly larger (P=0.003) than the reduction of systolic blood pressure by the addition of angiotensin receptor blockade (2% (1)) and was similar (P=0.14) to the reduction of systolic blood pressure by the addition of both angiotensin receptor blockade and low sodium diet (9% (1)), to ACE inhibition. Dietary sodium restriction to a level recommended in guidelines was more effective than dual blockade for reduction of proteinuria and blood pressure in non-diabetic nephropathy. The findings support the combined endeavours of patients and health professionals to reduce sodium intake. Trial registration Netherlands Trial Register NTR675.

Moderate dietary sodium restriction added to angiotensin converting enzyme inhibition compared with dual blockade in lowering proteinuria and blood pressure: randomised controlled trial

PubMed Central

Slagman, Maartje C J; Waanders, Femke; Hemmelder, Marc H; Woittiez, Arend-Jan; Janssen, Wilbert M T; Lambers Heerspink, Hiddo J; Navis, Gerjan

2011-01-01

Objective To compare the effects on proteinuria and blood pressure of addition of dietary sodium restriction or angiotensin receptor blockade at maximum dose, or their combination, in patients with non-diabetic nephropathy receiving background treatment with angiotensin converting enzyme (ACE) inhibition at maximum dose. Design Multicentre crossover randomised controlled trial. Setting Outpatient clinics in the Netherlands. Participants 52 patients with non-diabetic nephropathy. Interventions All patients were treated during four 6 week periods, in random order, with angiotensin receptor blockade (valsartan 320 mg/day) or placebo, each combined with, consecutively, a low sodium diet (target 50 mmol Na+/day) and a regular sodium diet (target 200 mmol Na+/day), with a background of ACE inhibition (lisinopril 40 mg/day) during the entire study. The drug interventions were double blind; the dietary interventions were open label. Main outcome measures The primary outcome measure was proteinuria; the secondary outcome measure was blood pressure. Results Mean urinary sodium excretion, a measure of dietary sodium intake, was 106 (SE 5) mmol Na+/day during a low sodium diet and 184 (6) mmol Na+/day during a regular sodium diet (P<0.001). Geometric mean residual proteinuria was 1.68 (95% confidence interval 1.31 to 2.14) g/day during ACE inhibition plus a regular sodium diet. Addition of angiotensin receptor blockade to ACE inhibition reduced proteinuria to 1.44 (1.07 to 1.93) g/day (P=0.003), addition of a low sodium diet reduced it to 0.85 (0.66 to 1.10) g/day (P<0.001), and addition of angiotensin receptor blockade plus a low sodium diet reduced it to 0.67 (0.50 to 0.91) g/day (P<0.001). The reduction of proteinuria by the addition of a low sodium diet to ACE inhibition (51%, 95% confidence interval 43% to 58%) was significantly larger (P<0.001) than the reduction of proteinuria by the addition of angiotensin receptor blockade to ACE inhibition (21%, (8% to 32%) and was comparable (P=0.009, not significant after Bonferroni correction) to the reduction of proteinuria by the addition of both angiotensin receptor blockade and a low sodium diet to ACE inhibition (62%, 53% to 70%). Mean systolic blood pressure was 134 (3) mm Hg during ACE inhibition plus a regular sodium diet. Mean systolic blood pressure was not significantly altered by the addition of angiotensin receptor blockade (131 (3) mm Hg; P=0.12) but was reduced by the addition of a low sodium diet (123 (2) mm Hg; P<0.001) and angiotensin receptor blockade plus a low sodium diet (121 (3) mm Hg; P<0.001) to ACE inhibition. The reduction of systolic blood pressure by the addition of a low sodium diet (7% (SE 1%)) was significantly larger (P=0.003) than the reduction of systolic blood pressure by the addition of angiotensin receptor blockade (2% (1)) and was similar (P=0.14) to the reduction of systolic blood pressure by the addition of both angiotensin receptor blockade and low sodium diet (9% (1)), to ACE inhibition. Conclusions Dietary sodium restriction to a level recommended in guidelines was more effective than dual blockade for reduction of proteinuria and blood pressure in non-diabetic nephropathy. The findings support the combined endeavours of patients and health professionals to reduce sodium intake. Trial registration Netherlands Trial Register NTR675. PMID:21791491

Opposite modulation of brain stimulation reward by NMDA and AMPA receptors in the ventral tegmental area

PubMed Central

Ducrot, Charles; Fortier, Emmanuel; Bouchard, Claude; Rompré, Pierre-Paul

2013-01-01

Previous studies have shown that blockade of ventral tegmental area (VTA) glutamate N-Methyl-D-Aspartate (NMDA) receptors induces reward, stimulates forward locomotion and enhances brain stimulation reward. Glutamate induces two types of excitatory response on VTA neurons, a fast and short lasting depolarization mediated by α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors and a longer lasting depolarization mediated by NMDA receptors. A role for the two glutamate receptors in modulation of VTA neuronal activity is evidenced by the functional change in AMPA and NMDA synaptic responses that result from repeated exposure to reward. Since both receptors contribute to the action of glutamate on VTA neuronal activity, we studied the effects of VTA AMPA and NMDA receptor blockade on reward induced by electrical brain stimulation. Experiments were performed on rats trained to self-administer electrical pulses in the medial posterior mesencephalon. Reward thresholds were measured with the curve-shift paradigm before and for 2 h after bilateral VTA microinjections of the AMPA antagonist, NBQX (2,3,-Dioxo-6-nitro-1,2,3,4-tetrahydrobenzo(f)quinoxaline-7-sulfonamide, 0, 80, and 800 pmol/0.5 μl/side) and of a single dose (0.825 nmol/0.5 μl/side) of the NMDA antagonist, PPPA (2R,4S)-4-(3-Phosphonopropyl)-2-piperidinecarboxylic acid). NBQX produced a dose-dependent increase in reward threshold with no significant change in maximum rate of responding. Whereas PPPA injected at the same VTA sites produced a significant time dependent decrease in reward threshold and increase in maximum rate of responding. We found a negative correlation between the magnitude of the attenuation effect of NBQX and the enhancement effect of PPPA; moreover, NBQX and PPPA were most effective when injected, respectively, into the anterior and posterior VTA. These results suggest that glutamate acts on different receptor sub-types, most likely located on different VTA neurons, to modulate reward. PMID:24106463

Opposite modulation of brain stimulation reward by NMDA and AMPA receptors in the ventral tegmental area.

PubMed

Ducrot, Charles; Fortier, Emmanuel; Bouchard, Claude; Rompré, Pierre-Paul

2013-01-01

Previous studies have shown that blockade of ventral tegmental area (VTA) glutamate N-Methyl-D-Aspartate (NMDA) receptors induces reward, stimulates forward locomotion and enhances brain stimulation reward. Glutamate induces two types of excitatory response on VTA neurons, a fast and short lasting depolarization mediated by α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors and a longer lasting depolarization mediated by NMDA receptors. A role for the two glutamate receptors in modulation of VTA neuronal activity is evidenced by the functional change in AMPA and NMDA synaptic responses that result from repeated exposure to reward. Since both receptors contribute to the action of glutamate on VTA neuronal activity, we studied the effects of VTA AMPA and NMDA receptor blockade on reward induced by electrical brain stimulation. Experiments were performed on rats trained to self-administer electrical pulses in the medial posterior mesencephalon. Reward thresholds were measured with the curve-shift paradigm before and for 2 h after bilateral VTA microinjections of the AMPA antagonist, NBQX (2,3,-Dioxo-6-nitro-1,2,3,4-tetrahydrobenzo(f)quinoxaline-7-sulfonamide, 0, 80, and 800 pmol/0.5 μl/side) and of a single dose (0.825 nmol/0.5 μl/side) of the NMDA antagonist, PPPA (2R,4S)-4-(3-Phosphonopropyl)-2-piperidinecarboxylic acid). NBQX produced a dose-dependent increase in reward threshold with no significant change in maximum rate of responding. Whereas PPPA injected at the same VTA sites produced a significant time dependent decrease in reward threshold and increase in maximum rate of responding. We found a negative correlation between the magnitude of the attenuation effect of NBQX and the enhancement effect of PPPA; moreover, NBQX and PPPA were most effective when injected, respectively, into the anterior and posterior VTA. These results suggest that glutamate acts on different receptor sub-types, most likely located on different VTA neurons, to modulate reward.

Assessing the role of metabotropic glutamate receptor 5 in multiple nociceptive modalities.

PubMed

Zhu, Chang Z; Wilson, Sonya G; Mikusa, Joseph P; Wismer, Carol T; Gauvin, Donna M; Lynch, James J; Wade, Carrie L; Decker, Michael W; Honore, Prisca

2004-12-15

Preclinical data, performed in a limited number of pain models, suggest that functional blockade of metabotropic glutamate (mGlu) receptors may be beneficial for pain management. In the present study, effects of 2-methyl-6-(phenylethynyl)-pyridine (MPEP), a potent, selective mGlu5 receptor antagonist, were examined in a wide variety of rodent nociceptive and hypersensitivity models in order to fully characterize the potential analgesic profile of mGlu5 receptor blockade. Effects of 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine (MTEP), as potent and selective as MPEP at mGlu5/mGlu1 receptors but more selective than MPEP at N-methyl-aspartate (NMDA) receptors, were also evaluated in selected nociceptive and side effect models. MPEP (3-30 mg/kg, i.p.) produced a dose-dependent reversal of thermal and mechanical hyperalgesia following complete Freund's adjuvant (CFA)-induced inflammatory hypersensitivity. Additionally, MPEP (3-30 mg/kg, i.p.) decreased thermal hyperalgesia observed in carrageenan-induced inflammatory hypersensitivity without affecting paw edema, abolished acetic acid-induced writhing activity in mice, and was shown to reduce mechanical allodynia and thermal hyperalgesia observed in a model of post-operative hypersensitivity and formalin-induced spontaneous pain. Furthermore, at 30 mg/kg, i.p., MPEP significantly attenuated mechanical allodynia observed in three neuropathic pain models, i.e. spinal nerve ligation, sciatic nerve constriction and vincristine-induced neuropathic pain. MTEP (3-30 mg/kg, i.p.) also potently reduced CFA-induced thermal hyperalgesia. However, at 100 mg/kg, i.p., MPEP and MTEP produced central nerve system (CNS) side effects as measured by rotarod performance and exploratory locomotor activity. These results suggest a role for mGlu5 receptors in multiple nociceptive modalities, though CNS side effects may be a limiting factor in developing mGlu5 receptor analgesic compounds.

Role of Endocannabinoids and Cannabinoid-1 Receptors in Cerebrocortical Blood Flow Regulation

PubMed Central

Horváth, Béla; Benkő, Rita; Lacza, Zsombor; Járai, Zoltán; Sándor, Péter; Di Marzo, Vincenzo; Pacher, Pál; Benyó, Zoltán

2013-01-01

Background Endocannabinoids are among the most intensively studied lipid mediators of cardiovascular functions. In the present study the effects of decreased and increased activity of the endocannabinoid system (achieved by cannabinoid-1 (CB1) receptor blockade and inhibition of cannabinoid reuptake, respectively) on the systemic and cerebral circulation were analyzed under steady-state physiological conditions and during hypoxia and hypercapnia (H/H). Methodology/Principal Findings In anesthetized spontaneously ventilating rats the CB1-receptor antagonist/inverse agonist AM-251 (10 mg/kg, i.v.) failed to influence blood pressure (BP), cerebrocortical blood flow (CoBF, measured by laser-Doppler flowmetry) or arterial blood gas levels. In contrast, the putative cannabinoid reuptake inhibitor AM-404 (10 mg/kg, i.v.) induced triphasic responses, some of which could be blocked by AM-251. Hypertension during phase I was resistant to AM-251, whereas the concomitant CoBF-increase was attenuated. In contrast, hypotension during phase III was sensitive to AM-251, whereas the concomitant CoBF-decrease was not. Therefore, CoBF autoregulation appeared to shift towards higher BP levels after CB1-blockade. During phase II H/H developed due to respiratory depression, which could be inhibited by AM-251. Interestingly, however, the concomitant rise in CoBF remained unchanged after AM-251, indicating that CB1-blockade potentially enhanced the reactivity of the CoBF to H/H. In accordance with this hypothesis, AM-251 induced a significant enhancement of the CoBF responses during controlled stepwise H/H. Conclusion/Significance Under resting physiological conditions CB1-receptor mediated mechanisms appear to have limited influence on systemic or cerebral circulation. Enhancement of endocannabinoid levels, however, induces transient CB1-independent hypertension and sustained CB1-mediated hypotension. Furthermore, enhanced endocannabinoid activity results in respiratory depression in a CB1-dependent manner. Finally, our data indicate for the first time the involvement of the endocannabinoid system and CB1-receptors in the regulation of the cerebral circulation during H/H and also raise the possibility of their contribution to the autoregulation of CoBF. PMID:23308211

Role of adenosine and the orexinergic perifornical hypothalamus in sleep-promoting effects of ethanol.

PubMed

Sharma, Rishi; Sahota, Pradeep; Thakkar, Mahesh M

2014-03-01

Strong clinical and preclinical evidence suggests that acute ethanol promotes sleep. However, very little is known about how and where ethanol acts to promote sleep. We hypothesized that ethanol may induce sleep by increasing extracellular levels of adenosine and inhibiting orexin neurons in the perifornical hypothalamus. Experiments 1 and 2: Within-Subject Design; Experiment 3: Between-Subject Design. N/A. N/A. N/A. Using adult male Sprague-Dawley rats as our animal model, we performed three experiments to test our hypothesis. Our first experiment examined the effect of A1 receptor blockade in the orexinergic perifornical hypothalamus on sleep- promoting effects of ethanol. Bilateral microinjection of the selective A1 receptor antagonist 1,3-dipropyl-8-phenylxanthine (500 μM; 250 nL/side) into orexinergic perifornical hypothalamus significantly reduced nonrapid eye movement sleep with a concomitant increase in wakefulness, suggesting that blockade of adenosine A1 receptor attenuates ethanol-induced sleep promotion. Our second experiment examined adenosine release in the orexinergic perifornical hypothalamus during local ethanol infusion. Local infusion of pharmacologically relevant doses of ethanol significantly and dose-dependently increased adenosine release. Our final experiment used c-Fos immunohistochemistry to examine the effects of ethanol on the activation of orexin neurons. Acute ethanol exposure significantly reduced the number of orexin neurons containing c-Fos, suggesting an inhibition of orexin neurons after ethanol intake. Based on our results, we believe that ethanol promotes sleep by increasing adenosine in the orexinergic perifornical hypothalamus, resulting in A1 receptor-mediated inhibition of orexin neurons.

Neurokinin-1 receptor antagonists CP-96,345 and L-733,060 protect mice from cytokine-mediated liver injury.

PubMed

Bang, Renate; Sass, Gabriele; Kiemer, Alexandra K; Vollmar, Angelika M; Neuhuber, Winfried L; Tiegs, Gisa

2003-04-01

Previously, we have shown that primary afferent sensory neurons are necessary for disease activity in T cell-mediated immune hepatitis in mice. In the present study, we analyzed the possible role of substance P (SP), an important proinflammatory neuropeptide of these nerve fibers, in an in vivo mouse model of liver inflammation. Liver injury was induced by bacterial lipopolysaccharide (LPS) in D-galactosamine (GalN)-sensitized mice. Depletion of primary afferent nerve fibers by neonatal capsaicin treatment down-regulated circulating levels of the proinflammatory cytokines tumor necrosis factor-alpha (TNFalpha) and interferon-gamma (IFNgamma) and protected mice from GalN/LPS-induced liver injury. Likewise, pretreatment of mice with antagonists of the SP-specific neurokinin-1 receptor (NK-1R), i.e., (2S,3S)-cis-2-(diphenylmethyl)-N-((2-methoxyphenyl)-methyl)-1-azabicyclo(2.2.2.)-octan-3-amine (CP-96,345) and (2S,3S)3-([3,5-bis(trifluoromethyl)phenyl]methoxy)-2-phenylpiperidine (L-733,060), dose dependently protected mice from GalN/LPS-induced liver injury. The presence of the NK-1R in the murine liver was demonstrated by reverse transcription-polymerase chain reaction, sequence analysis, and immunocytochemistry. NK-1R blockade reduced inflammatory liver damage, i.e., edema formation, neutrophil infiltration, hepatocyte apoptosis, and necrosis. To get further insight into the mechanism by which receptor blockade attenuated GalN/LPS-induced liver damage, we analyzed plasma levels and intrahepatic expression of TNFalpha, IFNgamma, interleukin (IL)-6, and IL-10. NK-1R blockade clearly inhibited GalN/LPS-induced production of TNFalpha and IFNgamma, whereas synthesis of the hepatoprotective cytokines IL-6 and IL-10 was increased. NK-1 receptor antagonists might be potent drugs for treatment of inflammatory liver disease, most likely by inhibiting SP effects.

CCR2 antagonism leads to marked reduction in proteinuria and glomerular injury in murine models of focal segmental glomerulosclerosis (FSGS)

PubMed Central

Miao, Zhenhua; Ertl, Linda S.; Newland, Dale; Zhao, Bin; Wang, Yu; Zang, Xiaoping; Campbell, James J.; Liu, Xiaoli; Dang, Ton; Miao, Shichang; Krasinski, Antoni; Punna, Sreenivas; Zeng, Yibin; McMahon, Jeffrey; Zhang, Penglie; Charo, Israel F.; Schall, Thomas J.

2018-01-01

Focal segmental glomerulosclerosis (FSGS) comprises a group of uncommon disorders that present with marked proteinuria, nephrotic syndrome, progressive renal failure and characteristic glomerular lesions on histopathology. The current standard of care for patients with FSGS include immunosuppressive drugs such as glucocorticoids followed by calcineurin inhibitors, if needed for intolerance or inadequate response to glucocorticoids. Renin-angiotensin-aldosterone (RAAS) blockers are also used to control proteinuria, an important signature of FSGS. Existing treatments, however, achieved only limited success. Despite best care, treatment failure is common and FSGS is causal in a significant proportion of end stage renal disease. Thus, an unmet need exists for novel disease modifying treatments for FSGS. We employed two widely-used murine models of FSGS to test the hypothesis that systemic inhibition of chemokine receptor CCR2 would have therapeutic benefit. Here we report that administration CCX872, a potent and selective small molecule antagonist of CCR2, achieved rapid and sustained attenuation of renal damage as determined by urine albumin excretion and improved histopathological outcome. Therapeutic benefit was present when CCX872 was used as a single therapy, and moreover, the combination of CCX872 and RAAS blockade was statistically more effective than RAAS blockade alone. In addition, the combination of CCR2 and RAAS blockade was equally as effective as endothelin receptor inhibition. We conclude that specific inhibition of CCR2 is effective in the Adriamycin-induced and 5/6 nephrectomy murine models of FSGS, and thus holds promise as a mechanistically distinct therapeutic addition to the treatment of human FSGS. PMID:29561839

The Non-Classical Renin-Angiotensin System and Renal Function

PubMed Central

Chappell, Mark C.

2014-01-01

The renin-angiotensin-system (RAS) constitutes one of the most important hormonal systems in the physiological regulation of blood pressure through renal and non-renal mechanisms. Indeed, dysregulation of the RAS is considered a major factor in the development of cardiovascular pathologies including kidney injury and blockade of this system by the inhibition of angiotensin converting enzyme (ACE) or blockade of the angiotensin type 1 receptor (AT1R) by selective antagonists constitutes an effective therapeutic regimen. It is now apparent with the identification of multiple components of the RAS within the kidney and other tissues that the system is actually composed of different angiotensin peptides with diverse biological actions mediated by distinct receptor subtypes. The classic RAS can be defined as the ACE-Ang II AT1R axis that promotes vasoconstriction, water intake, sodium retention and other mechanisms to maintain blood pressure, as well as increase oxidative stress, fibrosis, cellular growth and inflammation in pathological conditions. In contrast, the non-classical RAS composed primarily of the AngII/Ang III–AT2R pathway and the ACE2-Ang-(1-7)-AT7R axis generally opposes the actions of a stimulated Ang II-AT1R axis through an increase in nitric oxide and prostaglandins and mediates vasodilation, natriuresis, diuresis, and a reduced oxidative stress. Moreover, increasing evidence suggests that these non-classical RAS components contribute to the therapeutic blockade of the classical system to reduce blood pressure and attenuate various indices of renal injury, as well as contribute to normal renal function. PMID:23720263

ROLES OF OPIOID RECEPTOR SUBTYPES IN MEDIATING ALCOHOL SEEKING INDUCED BY DISCRETE CUES AND CONTEXT

PubMed Central

Marinelli, Peter W.; Funk, Douglas; Harding, Stephen; Li, Zhaoxia; Juzytsch, Walter; Lê, A.D.

2009-01-01

The aim of this study was to assess the effects of selective blockade of the delta (DOP) or mu opioid (MOP) receptors on alcohol seeking induced by discrete cues and context. In Experiment 1, rats were trained to self-administer alcohol in an environment with distinct sensory properties. After extinction in a different context with separate sensory properties, rats were tested for context-induced renewal in the original context following treatment with the DOP receptor antagonist naltrindole (0 – 15-mg/kg, IP) or the MOP receptor antagonist CTOP (0 – 3-µg/kg ICV). In a separate set of experiments, reinstatement was tested with the presentation of a discrete light+tone cue previously associated with alcohol delivery, following extinction without the cue. In Experiment 2, the effects of naltrindole (0 – 5-mg/kg, IP) or CTOP (0 – 3-µg/kg µg ICV) were assessed. For context-induced renewal, 7.5-mg/kg naltrindole reduced responding without affecting locomotor activity. Both doses of CTOP attenuated responding in the first 15 min of the renewal test session; however, total responses did not differ at the end of the session. For discrete cue-induced reinstatement, 1 and 5-mg/kg naltrindole attenuated responding, but CTOP had no effect. We conclude that while DOP receptors mediate alcohol seeking induced by discrete cues and context, MOP receptors may play a modest role only in context-induced renewal. These findings point to a differential involvement of opioid receptor subtypes in the effects of different kinds of conditioned stimuli on alcohol seeking, and support a more prominent role for DOP receptors. PMID:19686472

Opposing activities of Notch and Wnt signaling regulate intestinal stem cells and gut homeostasis

PubMed Central

Tian, Hua; Biehs, Brian; Chiu, Cecilia; Siebel, Chris; Wu, Yan; Costa, Mike; de Sauvage, Frederic J.; Klein, Ophir D.

2015-01-01

Summary Proper organ homeostasis requires tight control of adult stem cells and differentiation through integration of multiple inputs. In the mouse small intestine, Notch and Wnt signaling are required both for stem cell maintenance and for a proper balance of differentiation between secretory and absorptive cell lineages. In the absence of Notch signaling, stem cells preferentially generate secretory cells at the expense of absorptive cells. Here, we use function-blocking antibodies against Notch receptors to demonstrate that Notch blockade perturbs intestinal stem cell function by causing a de-repression of the Wnt signaling pathway, leading to mis-expression of prosecretory genes. Importantly, attenuation of the Wnt pathway rescued the phenotype associated with Notch blockade. These studies bring to light a negative regulatory mechanism that maintains stem cell activity and balanced differentiation, and we propose that the interaction between Wnt and Notch signaling described here represents a common theme in adult stem cell biology. PMID:25818302

Nucleus Accumbens Acetylcholine Receptors Modulate Dopamine and Motivation.

PubMed

Collins, Anne L; Aitken, Tara J; Greenfield, Venuz Y; Ostlund, Sean B; Wassum, Kate M

2016-11-01

Environmental reward-predictive cues can motivate reward-seeking behaviors. Although this influence is normally adaptive, it can become maladaptive in disordered states, such as addiction. Dopamine release in the nucleus accumbens core (NAc) is known to mediate the motivational impact of reward-predictive cues, but little is known about how other neuromodulatory systems contribute to cue-motivated behavior. Here, we examined the role of the NAc cholinergic receptor system in cue-motivated behavior using a Pavlovian-to-instrumental transfer task designed to assess the motivating influence of a reward-predictive cue over an independently-trained instrumental action. Disruption of NAc muscarinic acetylcholine receptor activity attenuated, whereas blockade of nicotinic receptors augmented cue-induced invigoration of reward seeking. We next examined a potential dopaminergic mechanism for this behavioral effect by combining fast-scan cyclic voltammetry with local pharmacological acetylcholine receptor manipulation. The data show evidence of opposing modulation of cue-evoked dopamine release, with muscarinic and nicotinic receptor antagonists causing suppression and augmentation, respectively, consistent with the behavioral effects of these manipulations. In addition to demonstrating cholinergic modulation of naturally-evoked and behaviorally-relevant dopamine signaling, these data suggest that NAc cholinergic receptors may gate the expression of cue-motivated behavior through modulation of phasic dopamine release.

The effects of AMPA receptor blockade in the prelimbic cortex on systemic and ventral tegmental area opiate reward sensitivity.

PubMed

De Jaeger, Xavier; Bishop, Stephanie F; Ahmad, Tasha; Lyons, Danika; Ng, Garye Ami; Laviolette, Steven R

2013-02-01

The medial prefrontal cortex (mPFC) is a key neural region involved in opiate-related reward memory processing. AMPA receptor transmission in the mPFC modulates opiate-related reward memory processing, and chronic opiate exposure is associated with alterations in intra-mPFC AMPA receptor function. The objectives of this study were to examine how pharmacological blockade of AMPA receptor transmission in the prelimbic (PLC) division of the mPFC may modulate opiate reward memory acquisition and whether opiate exposure state may modulate the functional role of intra-PLC AMPA receptor transmission during opiate reward learning. Using an unbiased conditioned place preference (CPP) procedure in rats, we performed discrete, bilateral intra-PLC microinfusions of the AMPA receptor antagonist, 6,7-dinitroquinoxaline-2,3-dione, prior to behavioral morphine CPP conditioning, using sub-reward threshold conditioning doses of either systemic (0.05 mg/kg; i.p.) or intra-ventral tegmental area (VTA) morphine (250 ng/0.5 μl). We show that, in both opiate-naïve and opiate-dependent states, intra-PLC blockade of AMPA receptor transmission, but not the infralimbic cortex, increases the behavioral reward magnitude of systemic or intra-VTA morphine. This effect is dependent on dopamine (DA)ergic signaling because pre-administration of cis-(Z)-flupenthixol-dihydrochloride (α-flu), a broad-spectrum dopamine receptor antagonist, blocked the morphine-reward potentiating effects of AMPA receptor blockade. These findings suggest a critical role for intra-PLC AMPA receptor transmission in the processing of opiate reward signaling. Furthermore, blockade of AMPA transmission specifically within the PLC is capable of switching opiate reward processing to a DA-dependent reward system, independently of previous opiate exposure history.

Analysis of G-Protein Coupled Receptor 30 (GPR30) on Endothelial Inflammation.

PubMed

Chakrabarti, Subhadeep; Davidge, Sandra T

2016-01-01

The female sex hormone estrogen (the most common form 17-β-estradiol or E2) is known to have both anti-inflammatory and pro-inflammatory effects. Given the diversity of estrogen responses mediated through its three distinct receptors, namely, estrogen receptor α (ERα), ERβ, and the G-protein coupled receptor 30 (GPR30), it is plausible that different receptors have specific modulatory effects on inflammation in different tissues. We have shown that activation of GPR30 exerted anti-inflammatory effects as demonstrated by significant attenuation of tumor necrosis factor (TNF)-mediated upregulation of adhesion molecules in isolated human umbilical vein endothelial cells. Interestingly, estrogen alone had no such effect and blockade of classical ERs restored the anti-inflammatory effect, suggesting that this effect was dependent on GPR30 and opposed to classical ERs. These findings were further validated by the negation of anti-inflammatory GPR30 effects by classical ER agonists. This chapter focuses on multiple pharmacological options to activate GPR30 and the use of TNF activated endothelial cells as a model system for inflammatory response as assessed by adhesion molecule detection through western blotting.

Blockade of the receptor for advanced glycation end products attenuates acetaminophen-induced hepatotoxicity in mice.

PubMed

Ekong, Udeme; Zeng, Shan; Dun, Hao; Feirt, Nikki; Guo, Jiancheng; Ippagunta, Nikalesh; Guarrera, James V; Lu, Yan; Weinberg, Alan; Qu, Wu; Ramasamy, Ravichandran; Schmidt, Ann Marie; Emond, Jean C

2006-04-01

Severe injury to the liver, such as that induced by toxic doses of acetaminophen, triggers a cascade of events leading to hepatocyte death. It is hypothesized that activation of the receptor for advanced glycation end products (RAGE) might contribute to acetaminophen-induced liver toxicity by virtue of its ability to generate reactive oxygen species, at least in part via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, and thereby activate downstream signaling pathways leading to cellular injury. A model was employed in which toxic doses of acetaminophen (1125 mg/kg) were administered to C57BL/6 mice. To block RAGE, mice received murine soluble (s) RAGE, the extracellular ligand binding domain of the receptor that acts as a decoy to interrupt ligand-RAGE signaling. Animals treated with sRAGE displayed increased survival compared with vehicle treatment, and markedly decreased hepatic necrosis. Consistent with an important role for RAGE-triggered oxidant stress in acetaminophen-induced injury, a significant reduction of nitrotyrosine protein adducts was observed in hepatic tissue in sRAGE-treated versus vehicle-treated mice receiving acetaminophen, in parallel with significantly increased levels of glutathione. In addition, pro-regenerative cytokines tumor necrosis factor-alpha and interleukin-6 were increased in sRAGE-treated versus vehicle-treated mice. These findings implicate RAGE-dependent mechanisms in acetaminophen-induced liver damage and suggest that blockade of this pathway may impart beneficial effects in toxin-induced liver injury.

Histamine H3 receptors aggravate cerebral ischaemic injury by histamine-independent mechanisms

PubMed Central

Yan, Haijing; Zhang, Xiangnan; Hu, Weiwei; Ma, Jing; Hou, Weiwei; Zhang, Xingzhou; Wang, Xiaofen; Gao, Jieqiong; Shen, Yao; Lv, Jianxin; Ohtsu, Hiroshi; Han, Feng; Wang, Guanghui; Chen, Zhong

2014-01-01

The role of the histamine H3 receptor (H3R) in cerebral ischaemia/reperfusion (I/R) injury remains unknown. Here we show that H3R expression is upregulated after I/R in two mouse models. H3R antagonists and H3R knockout attenuate I/R injury, which is reversed by an H3R-selective agonist. Interestingly, H1R and H2R antagonists, a histidine decarboxylase (HDC) inhibitor and HDC knockout all fail to compromise the protection by H3R blockade. H3R blockade inhibits mTOR phosphorylation and reinforces autophagy. The neuroprotection by H3R antagonism is reversed by 3-methyladenine and siRNA for Atg7, and is diminished in Atg5−/− mouse embryonic fibroblasts. Furthermore, the peptide Tat-H3RCT414-436, which blocks CLIC4 binding with H3Rs, or siRNA for CLIC4, further increases I/R-induced autophagy and protects against I/R injury. Therefore, H3R promotes I/R injury while its antagonism protects against ischaemic injury via histamine-independent mechanisms that involve suppressing H3R/CLIC4 binding-activated autophagy, suggesting that H3R inhibition is a therapeutic target for cerebral ischaemia. PMID:24566390

Modafinil attenuates reinstatement of cocaine seeking: role for cystine-glutamate exchange and metabotropic glutamate receptors.

PubMed

Mahler, Stephen V; Hensley-Simon, Megan; Tahsili-Fahadan, Pouya; LaLumiere, Ryan T; Thomas, Charles; Fallon, Rebecca V; Kalivas, Peter W; Aston-Jones, Gary

2014-01-01

Modafinil may be useful for treating stimulant abuse, but the mechanisms by which it acts to do so are unknown. Indeed, a primary effect of modafinil is to inhibit dopamine transport, which typically promotes rather than inhibits motivated behavior. Therefore, we examined the role of nucleus accumbens extracellular glutamate and the group II metabotropic glutamate receptor (mGluR2/3) in modafinil effects. One group of rats was trained to self-administer cocaine for 10 days and extinguished, then given priming injections of cocaine to elicit reinstatement. Modafinil (300 mg/kg, intraperitoneal) inhibited reinstated cocaine seeking (but did not alter extinction responding by itself), and this effect was prevented by pre-treatment with bilateral microinjections of the mGluR2/3 antagonist LY-341495 (LY) into nucleus accumbens core. No reversal of modafinil effects was seen after unilateral accumbens core LY, or bilateral LY in the rostral pole of accumbens. Next, we sought to explore effects of modafinil on extracellular glutamate levels in accumbens after chronic cocaine. Separate rats were administered non-contingent cocaine, and after 3 weeks of withdrawal underwent accumbens microdialysis. Modafinil increased extracellular accumbens glutamate in chronic cocaine, but not chronic saline-pre-treated animals. This increase was prevented by reverse dialysis of cystine-glutamate exchange or voltage-dependent calcium channel antagonists. Voltage-dependent sodium channel blockade partly attenuated the increase in glutamate, but mGluR1 blockade did not. We conclude that modafinil increases extracellular glutamate in nucleus accumbens from glial and neuronal sources in cocaine-exposed rats, which may be important for its mGluR2/3-mediated antirelapse properties. © 2012 The Authors, Addiction Biology © 2012 Society for the Study of Addiction.

Excitotoxicity in the Lung: N-Methyl-D-Aspartate-Induced, Nitric Oxide-Dependent, Pulmonary Edema is Attenuated by Vasoactive Intestinal Peptide and by Inhibitors of Poly(ADP-Ribose) Polymerase

NASA Astrophysics Data System (ADS)

Said, Sami I.; Berisha, Hasan I.; Pakbaz, Hedayatollah

1996-05-01

Excitatory amino acid toxicity, resulting from overactivation of N-methyl-D-aspartate (NMDA) glutamate receptors, is a major mechanism of neuronal cell death in acute and chronic neurological diseases. We have investigated whether excitotoxicity may occur in peripheral organs, causing tissue injury, and report that NMDA receptor activation in perfused, ventilated rat lungs triggered acute injury, marked by increased pressures needed to ventilate and perfuse the lung, and by high-permeability edema. The injury was prevented by competitive NMDA receptor antagonists or by channel-blocker MK-801, and was reduced in the presence of Mg2+. As with NMDA toxicity to central neurons, the lung injury was nitric oxide (NO) dependent: it required L-arginine, was associated with increased production of NO, and was attenuated by either of two NO synthase inhibitors. The neuropeptide vasoactive intestinal peptide and inhibitors of poly(ADP-ribose) polymerase also prevented this injury, but without inhibiting NO synthesis, both acting by inhibiting a toxic action of NO that is critical to tissue injury. The findings indicate that: (i) NMDA receptors exist in the lung (and probably elsewhere outside the central nervous system), (ii) excessive activation of these receptors may provoke acute edematous lung injury as seen in the ``adult respiratory distress syndrome,'' and (iii) this injury can be modulated by blockade of one of three critical steps: NMDA receptor binding, inhibition of NO synthesis, or activation of poly(ADP-ribose) polymerase.

[Influence of hydrocortisone and adrenaline against the background of mu- and delta-opiate receptors blockade on local immune response in mice].

PubMed

Geĭn, S V; Chizhova, E G; Tendriakova, S P

2006-07-01

In the induced phase of the immune response, the immunosuppressive effects of hydrocortisone and adrenaline were enhanced under mu- and delta-opiate receptor blockade. No changes were observed in the effects of hydrocortisone and adrenaline under mu- and delta-opiate receptor blockade in effector phase. In the induced phase of the immune response, selective agonists of mu- and delta-opiate receptors DAGO and DADLE enhanced antibody response, delayed-type hypersensitivity, and reduced the number of cells in the regional lymph node. Thus, our data suggest an equal role of mu- and delta-opiate receptors in regulation of expressiveness of local immune response.

The effects of stressful stimuli and hypothalamic-pituitary-adrenal axis activation are reversed by the melanin-concentrating hormone 1 receptor antagonist SNAP 94847 in rodents.

PubMed

Smith, Daniel G; Hegde, Laxminarayan G; Wolinsky, Toni D; Miller, Silke; Papp, Mariusz; Ping, Xiaoli; Edwards, Tanya; Gerald, Christophe P; Craig, Douglas A

2009-02-11

Melanin-concentrating hormone (MCH) is an orexigenic and dipsogenic neuropeptide that has been reported to mediate acute behavioral and neuroendocrine stress-related responses via MCH(1) receptor activation in rodents. The purpose of the present investigation was to use the MCH(1) receptor antagonist SNAP 94847 (N-(3-{1-[4-(3,4-difluoro-phenoxy)-benzyl]-piperidin-4-yl}-4-methyl-phenyl)-isobutyramide) to determine the effects of MCH(1) receptor blockade on MCH-evoked adrenocorticotropic hormone (ACTH) release, chronic mild stress-induced anhedonia, stress-induced hyperthermia and forced swim stress-induced immobility. The appropriate dose range for testing SNAP 94847 was determined by measuring MCH-evoked water drinking. The corresponding occupancy of MCH(1) receptors in rat striatum was also measured across a broad dose range. Orally administered (p.o.) SNAP 94847 (1-10 mg/kg) corresponds to 30-60% occupancy at MCH(1) receptors and significantly blocks water drinking induced by the intracerebroventricular (i.c.v.) injection of MCH. MCH (i.c.v.) significantly elevates plasma levels of ACTH in rats, and SNAP 94847 (2.5 mg/kg, p.o.) blocks MCH-evoked ACTH release. Using the chronic mild stress paradigm, we show that repeated daily exposure to environmental stressors for 5 weeks significantly suppresses sucrose intake in rats, and that SNAP 94847 (1 mg/kg, BID) for 1-5 weeks restores baseline sucrose intake. Moreover, a single administration of SNAP 94847 attenuates stress-induced hyperthermia and the behavioral effects of forced swim stress with minimal effective doses of 2.5 and 30 mg/kg (p.o.), respectively. The regulation of ACTH release and reversal of the effects of chronic and acute stress by SNAP 94847 are suggestive of a role for MCH(1) receptor blockade in the treatment of disorders characterized by high allostatic load.

Mineralocorticoid receptor blockade—a novel approach to fight hyperkalaemia in chronic kidney disease

PubMed Central

Ritz, E.; Pitt, B.

2013-01-01

Hyperkalaemia continues to be a major hazard of mineralocorticoid receptor blockade in an effort to retard the progression of chronic kidney disease (CKD). In cardiac patients on mineralocorticoid receptor blockade, RLY-5016 which captures K+ in the colon has been effective in reducing the risk of hyperkalaemia. This compound might be useful in CKD as well. PMID:26120440

Cardiac beta-adrenergic receptors and coronary hemodynamics in the conscious dog during hypoxic hypoxia.

NASA Technical Reports Server (NTRS)

Erickson, H. H.; Stone, H. L.

1972-01-01

The mechanisms by which acute hypoxia (10% and 5% oxygen) mediates changes in coronary blood flow and cardiac function were investigated in the conscious dog. When the dogs breathed hypoxic gas mixtures through a tracheostomy, both arterial and coronary sinus oxygen tensions were significantly decreased. With 5% oxygen, there were significant increases in heart rate (25%), maximum left ventricular dP/dt (39%), left circumflex coronary artery blood flow (163%), and left ventricular oxygen consumption (52%), which were attenuated by beta-adrenergic blockage with propranolol. When electrical pacing was used to keep the ventricular rate constant during hypoxia, there was no significant difference in coronary blood flow before and after beta blockade. Beta-adrenergic receptor activity in the myocardium participates in the integrated response to hypoxia although it may not cause active vasodilation of the coronary vessels.

Aortic remodeling after transverse aortic constriction in mice is attenuated with AT1 receptor blockade.

PubMed

Kuang, Shao-Qing; Geng, Liang; Prakash, Siddharth K; Cao, Jiu-Mei; Guo, Steven; Villamizar, Carlos; Kwartler, Callie S; Peters, Andrew M; Brasier, Allan R; Milewicz, Dianna M

2013-09-01

Although hypertension is the most common risk factor for thoracic aortic diseases, it is not understood how increased pressures on the ascending aorta lead to aortic aneurysms. We investigated the role of angiotensin II type 1 receptor activation in ascending aortic remodeling in response to increased biomechanical forces using a transverse aortic constriction (TAC) mouse model. Two weeks after TAC, the increased biomechanical pressures led to ascending aortic dilatation and thickening of the medial and adventitial layers of the aorta. There was significant adventitial hyperplasia and inflammatory responses in TAC ascending aortas were accompanied by increased adventitial collagen, elevated inflammatory and proliferative markers, and increased cell density attributable to accumulation of myofibroblasts and macrophages. Treatment with losartan significantly blocked TAC-induced vascular inflammation and macrophage accumulation. However, losartan only partially prevented TAC-induced adventitial hyperplasia, collagen accumulation, and ascending aortic dilatation. Increased Tgfb2 expression and phosphorylated-Smad2 staining in the medial layer of TAC ascending aortas were effectively blocked with losartan. In contrast, the increased Tgfb1 expression and adventitial phospho-Smad2 staining were only partially attenuated by losartan. In addition, losartan significantly blocked extracellular signal-regulated kinase activation and reactive oxygen species production in the TAC ascending aorta. Inhibition of the angiotensin II type 1 receptor using losartan significantly attenuated the vascular remodeling associated with TAC but did not completely block the increased transforming growth factor-β1 expression, adventitial Smad2 signaling, and collagen accumulation. These results help to delineate the aortic transforming growth factor-β signaling that is dependent and independent of the angiotensin II type 1 receptor after TAC.

Striatal D2/3 Binding Potential Values in Drug-Naïve First-Episode Schizophrenia Patients Correlate With Treatment Outcome

PubMed Central

Wulff, Sanne; Pinborg, Lars Hageman; Svarer, Claus; Jensen, Lars Thorbjørn; Nielsen, Mette Ødegaard; Allerup, Peter; Bak, Nikolaj; Rasmussen, Hans; Frandsen, Erik; Rostrup, Egill; Glenthøj, Birte Yding

2015-01-01

One of best validated findings in schizophrenia research is the association between blockade of dopamine D2 receptors and the effects of antipsychotics on positive psychotic symptoms. The aim of the present study was to examine correlations between baseline striatal D2/3 receptor binding potential (BPp) values and treatment outcome in a cohort of antipsychotic-naïve first-episode schizophrenia patients. Additionally, we wished to investigate associations between striatal dopamine D2/3 receptor blockade and alterations of negative symptoms as well as functioning and subjective well-being. Twenty-eight antipsychotic-naïve schizophrenia patients and 26 controls were included in the study. Single-photon emission computed tomography (SPECT) with [123I]iodobenzamide ([123I]-IBZM) was used to examine striatal D2/3 receptor BPp. Patients were examined before and after 6 weeks of treatment with the D2/3 receptor antagonist amisulpride. There was a significant negative correlation between striatal D2/3 receptor BPp at baseline and improvement of positive symptoms in the total group of patients. Comparing patients responding to treatment to nonresponders further showed significantly lower baseline BPp in the responders. At follow-up, the patients demonstrated a negative correlation between the blockade and functioning, whereas no associations between blockade and negative symptoms or subjective well-being were observed. The results show an association between striatal BPp of dopamine D2/3 receptors in antipsychotic-naïve first-episode patients with schizophrenia and treatment response. Patients with a low BPp have a better treatment response than patients with a high BPp. The results further suggest that functioning may decline at high levels of dopamine receptor blockade. PMID:25698711

AT1 receptor blockade in the central nucleus of the amygdala attenuates the effects of muscimol on sodium and water intake.

PubMed

Hu, B; Qiao, H; Sun, B; Jia, R; Fan, Y; Wang, N; Lu, B; Yan, J Q

2015-10-29

The blockade of the central nucleus of the amygdala (CeA) with the GABAA receptor agonist muscimol significantly reduces hypertonic NaCl and water intake by sodium-depleted rats. In the present study we investigated the effects of previous injection of losartan, an angiotensin II type-1 (AT1) receptor antagonist, into the CeA on 0.3M NaCl and water intake reduced by muscimol bilaterally injected into the same areas in rats submitted to water deprivation-partial rehydration (WD-PR) and in rats treated with the diuretic furosemide (FURO). Male Sprague-Dawley rats with stainless steel cannulas bilaterally implanted into the CeA were used. Bilateral injections of muscimol (0.2 nmol/0.5 μl, n=8 rats/group) into the CeA in WD-PR-treated rats reduced 0.3M NaCl intake and water intake, and pre-treatment of the CeA with losartan (50 μg/0.5 μl) reversed the inhibitory effect of muscimol. The negative effect of muscimol on sodium and water intake could also be blocked by pretreatment with losartan microinjected into the CeA in rats given FURO (n=8 rats/group). However, bilateral injections of losartan (50 μg/0.5 μl) alone into the CeA did not affect the NaCl or water intake. These results suggest that the deactivation of CeA facilitatory mechanisms by muscimol injection into the CeA is promoted by endogenous angiotensin II acting on AT1 receptors in the CeA, which prevents rats from ingesting large amounts of hypertonic NaCl and water. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

Endothelin Receptor-A Antagonist Attenuates Retinal Vascular and Neuroretinal Pathology in Diabetic Mice

PubMed Central

Chou, Jonathan C.; Rollins, Stuart D.; Ye, Minghao; Batlle, Daniel; Fawzi, Amani A.

2014-01-01

Purpose. We sought to determine the effects of atrasentan, a selective endothelin-A receptor antagonist, on the retinal vascular and structural integrity in a db/db mouse, an animal model of type 2 diabetes and diabetic retinopathy. Methods. Diabetic mice, 23 weeks old, were given either atrasentan or vehicle treatment in drinking water for 8 weeks. At the end of the treatment period, eyes underwent trypsin digest to assess the retinal vascular pathology focusing on capillary degeneration, endothelial cell, and pericyte loss. Paraffin-embedded retinal cross sections were used to evaluate retinal sublayer thickness both near the optic nerve and in the retinal periphery. Immunohistochemistry and TUNEL assay were done to evaluate retinal cellular and vascular apoptosis. Results. Compared with untreated db/db mice, atrasentan treatment was able to ameliorate the retinal vascular pathology by reducing pericyte loss (29.2% ± 0.4% vs. 44.4% ± 2.0%, respectively, P < 0.05) and capillary degeneration as determined by the percentage of acellular capillaries (8.6% ± 0.3% vs. 3.3% ± 0.41%, respectively, P < 0.05). A reduction in inner retinal thinning both at the optic nerve and at the periphery in treated diabetic mice was also observed in db/db mice treated with atrasentan as compared with untreated db/db mice (P < 0.05). TUNEL assay suggested that atrasentan may decrease enhanced apoptosis in neuroretinal layers and vascular pericytes in the db/db mice. Conclusions. Endothelin-A receptor blockade using atrasentan significantly reduces the vascular and neuroretinal complications in diabetic mice. Endothelin-A receptor blockade is a promising therapeutic target in diabetic retinopathy. PMID:24644048

Inhibition of lysophosphatidic acid receptors 1 and 3 attenuates atherosclerosis development in LDL-receptor deficient mice.

PubMed

Kritikou, Eva; van Puijvelde, Gijs H M; van der Heijden, Thomas; van Santbrink, Peter J; Swart, Maarten; Schaftenaar, Frank H; Kröner, Mara J; Kuiper, Johan; Bot, Ilze

2016-11-24

Lysophosphatidic acid (LPA) is a natural lysophospholipid present at high concentrations within lipid-rich atherosclerotic plaques. Upon local accumulation in the damaged vessels, LPA can act as a potent activator for various types of immune cells through its specific membrane receptors LPA 1/3. LPA elicits chemotactic, pro-inflammatory and apoptotic effects that lead to atherosclerotic plaque progression. In this study we aimed to inhibit LPA signaling by means of LPA 1/3 antagonism using the small molecule Ki16425. We show that LPA 1/3 inhibition significantly impaired atherosclerosis progression. Treatment with Ki16425 also resulted in reduced CCL2 production and secretion, which led to less monocyte and neutrophil infiltration. Furthermore, we provide evidence that LPA 1/3 blockade enhanced the percentage of non-inflammatory, Ly6C low monocytes and CD4 + CD25 + FoxP3 + T-regulatory cells. Finally, we demonstrate that LPA 1/3 antagonism mildly reduced plasma LDL cholesterol levels. Therefore, pharmacological inhibition of LPA 1/3 receptors may prove a promising approach to diminish atherosclerosis development.

Glutamate Receptors in the Central Nucleus of the Amygdala Mediate Cisplatin-Induced Malaise and Energy Balance Dysregulation through Direct Hindbrain Projections.

PubMed

Alhadeff, Amber L; Holland, Ruby A; Nelson, Alexandra; Grill, Harvey J; De Jonghe, Bart C

2015-08-05

Cisplatin chemotherapy is used commonly to treat a variety of cancers despite severe side effects such as nausea, vomiting, and anorexia that compromise quality of life and limit treatment adherence. The neural mechanisms mediating these side effects remain elusive despite decades of clinical use. Recent data highlight the dorsal vagal complex (DVC), lateral parabrachial nucleus (lPBN), and central nucleus of the amygdala (CeA) as potential sites of action in mediating the side effects of cisplatin. Here, results from immunohistochemical studies in rats identified a population of cisplatin-activated DVC neurons that project to the lPBN and a population of cisplatin-activated lPBN calcitonin gene-related peptide (CGRP, a marker for glutamatergic neurons in the lPBN) neurons that project to the CeA, outlining a neuroanatomical circuit that is activated by cisplatin. CeA gene expressions of AMPA and NMDA glutamate receptor subunits were markedly increased after cisplatin treatment, suggesting that CeA glutamate receptor signaling plays a role in mediating cisplatin side effects. Consistent with gene expression results, behavioral/pharmacological data showed that CeA AMPA/kainate receptor blockade attenuates cisplatin-induced pica (a proxy for nausea/behavioral malaise in nonvomiting laboratory rodents) and that CeA NMDA receptor blockade attenuates cisplatin-induced anorexia and body weight loss in addition to pica, demonstrating that glutamate receptor signaling in the CeA is critical for the energy balance dysregulation caused by cisplatin treatment. Together, these data highlight a novel circuit and CGRP/glutamatergic mechanism through which cisplatin-induced malaise and energy balance dysregulation are mediated. To treat cancer effectively, patients must follow prescribed chemotherapy treatments without interruption, yet most cancer treatments produce side effects that devastate quality of life (e.g., nausea, vomiting, anorexia, weight loss). Although hundreds of thousands of patients undergo chemotherapies each year, the neural mechanisms mediating their side effects are unknown. The current data outline a neural circuit activated by cisplatin chemotherapy and demonstrate that glutamate signaling in the amygdala, arising from hindbrain projections, is required for the full expression of cisplatin-induced malaise, anorexia, and body weight loss. Together, these data help to characterize the neural circuits and neurotransmitters mediating chemotherapy-induced energy balance dysregulation, which will ultimately provide an opportunity for the development of well tolerated cancer and anti-emetic treatments. Copyright © 2015 the authors 0270-6474/15/3511094-11$15.00/0.

InsR/IGF1R pathway mediates resistance to EGFR inhibitors in glioblastoma

PubMed Central

Ma, Yufang; Tang, Nan; Thompson, Reid; Mobley, Bret C.; Clark, Steven W.; Sarkaria, Jann N.; Wang, Jialiang

2015-01-01

Purpose Aberrant activation of epidermal growth factor receptor (EGFR) is a hallmark of glioblastoma. However, EGFR inhibitors exhibit at best modest efficacy in glioblastoma. This is in sharp contrast to the observations in EGFR-mutant lung cancer. We examined whether activation of functionally redundant receptor tyrosine kinases (RTKs) conferred resistance to EGFR inhibitors in glioblastoma. Experimental Design We collected a panel of patient-derived glioblastoma xenograft (PDX) lines that maintained expression of wild type or mutant EGFR in serial xenotransplantation and tissue cultures. Using this physiologically relevant platform, we tested the abilities of several RTK ligands to protect glioblastoma cells against an EGFR inhibitor, gefitinib. Based on the screening results, we further developed a combination therapy co-targeting EGFR and insulin receptor (InsR)/insulin-like growth factor 1 receptor (IGF1R). Results Insulin and IGF1 induced significant protection against gefitinib in the majority of EGFR-dependent PDX lines with one exception that did not expression InsR or IGF1R. Blockade of the InsR/IGF1R pathway synergistically improved sensitivity to gefitinib or dacomitinib. Gefitinib alone effectively attenuated EGFR activities and the downstream MEK/ERK pathway. However, repression of AKT and induction of apoptosis required concurrent inhibition of both EGFR and InsR/IGF1R. A combination of gefitinib and OSI-906, a dual InsR/IGF1R inhibitor, was more effective than either agent alone to treat subcutaneous glioblastoma xenograft tumors. Conclusions Our results suggest that activation of the InsR/IGF1R pathway confers resistance to EGFR inhibitors in EGFR-dependent glioblastoma through AKT regulation. Concurrent blockade of these two pathways holds promise to treat EGFR-dependent glioblastoma. PMID:26561558

The selective cyclooxygenase-2 inhibitor parecoxib markedly improves the ability of the duodenum to regulate luminal hypertonicity in anaesthetized rats.

PubMed

Sedin, J; Sjöblom, M; Nylander, O

2012-07-01

To examine whether the prevention of post-operative duodenal ileus by treatment with parecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, affects the ability of the duodenum to respond to luminal hypertonicity. The proximal duodenums of anaesthetized rats were perfused with hypertonic NaCl solutions with osmolalities of 400, 500, 600 or 700 mOsm kg(-1) , and the effects on mucosal permeability, motility, transepithelial net fluid flux and effluent osmolality were assessed in the absence (control) and presence of parecoxib. Parecoxib-treated, but not control animals, exhibited duodenal contractions, which were reduced by the nicotinic receptor antagonists mecamylamine and hexamethonium and by perfusion with 700 mOsm kg(-1) . All animals responded to luminal hypertonicity with induction of net fluid secretion, which peaked at an osmolality of 500 mOsm kg(-1) . The hypertonicity-induced increases in fluid secretion were twofold greater in parecoxib-treated than in control rats and attenuated by nicotinic receptor blockade. The decrease in luminal osmolality correlated with the osmolality of the perfusion solution in both control and parecoxib-treated animals but the osmolality-adjusting capability was markedly better in the latter group. Rats exposed to duodenal luminal distension responded to hypertonicity with a greater fluid secretion and a larger decrease in luminal osmolality than control rats. Perfusion with 700 mOsm kg(-1) increased mucosal permeability in parecoxib-treated animals only, an effect abolished by nicotinic receptor blockade. Parecoxib markedly improved the ability of the duodenum to sense and to decrease luminal hypertonicity by a mechanism most probably involving inhibition of COX-2 and stimulation of nicotinic acetylcholine receptors. © 2012 The Authors Acta Physiologica © 2012 Scandinavian Physiological Society.

Antagonists of toll like receptor 4 maybe a new strategy to counteract opioid-induced hyperalgesia and opioid tolerance.

PubMed

Li, Qian

2012-12-01

Long term opioid treatment results in hyperalgesia and tolerance, which is a troublesome phenomenon in clinic application. Recent studies have revealed a critical role of toll-like receptor 4 (TLR4) in the neuropathological process of opioid-induced hyperalgesia and tolerance. TLR4 is predominantly expressed by microglial cells and is a key modulator in the activation of the innate immune system. Activation of TLR4 may initiate the activation of microglia and hence a number of neurotransmitters and neuromodulators that could enhance neuronal excitability are released. Blockade of TLR4 activation by its antagonists alleviate neuropathic pain. We hypothesized that opioid antagonists such as naloxone and naltrexone, which were also demonstrated to be TLR4 antagonist, may have clinic application value in attenuation of opioid-induced hyperalgesia and tolerance. Copyright © 2012 Elsevier Ltd. All rights reserved.

Protection against methamphetamine-induced neurotoxicity to neostriatal dopaminergic neurons by adenosine receptor activation.

PubMed

Delle Donne, K T; Sonsalla, P K

1994-12-01

Methamphetamine (METH)-induced neurotoxicity to nigrostriatal dopaminergic neurons in experimental animals appears to have a glutamatergic component because blockade of N-methyl-D-aspartate receptors prevents the neuropathologic consequences. Because adenosine affords neuroprotection against various forms of glutamate-mediated neuronal damage, the present studies were performed to investigate whether adenosine plays a protective role in METH-induced toxicity. METH-induced decrements in neostriatal dopamine content and tyrosine hydroxylase activity in mice were potentiated by concurrent treatment with caffeine, a nonselective adenosine antagonist that blocks both A1 and A2 adenosine receptors. In contrast, chronic treatment of mice with caffeine through their drinking water for 4 weeks, which increased the number of adenosine A1 receptors in the neostriatum and frontal cortex, followed by drug washout, prevented the neurochemical changes produced by the treatment of mice with METH treatment. In contrast, this treatment did not prevent 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine-induced dopaminergic neurotoxicity. Furthermore, concurrent administration of cyclopentyladenosine, an adenosine A1 receptor agonist, attenuated the METH-induced neurochemical changes. This protection by cyclopentyladenosine was blocked by cyclopentyltheophylline, an A1 receptor antagonist. These results indicate that activation of A1 receptors can protect against METH-induced neurotoxicity in mice.

EXTRINSIC COAGULATION BLOCKADE ATTENUATES LUNG INJURY AND PROINFLAMMATORY CYTOKINE RELEASE AFTER INTRATRACHEAL LIPOPOLYSACCHARIDE

EPA Science Inventory

Initiation of coagulation by tissue factor (TF) is a potentially powerful regulator of local inflammatory responses. We hypothesized that blockade of TF-factor VIIa (FVIIa) complex would decrease lung inflammation and proinflammatory cytokine release after tracheal instillation o...

Sex-specific effect of endothelin in the blood pressure response to acute angiotensin II in growth-restricted rats

PubMed Central

Intapad, Suttira; Ojeda, Norma B.; Varney, Elliott; Royals, Thomas P.; Alexander, Barbara T.

2015-01-01

The renal endothelin system contributes to sex differences in blood pressure with males demonstrating greater endothelin type-A receptor-mediated responses relative to females. Intrauterine growth restriction programs hypertension and enhanced renal sensitivity to acute angiotensin II in male growth-restricted rats. Endothelin is reported to work synergistically with angiotensin II. Thus, this study tested the hypothesis that endothelin augments the blood pressure response to acute angiotensin II in male growth-restricted rats. Systemic and renal hemodynamics were determined in response to acute angiotensin II (100 nanogram/kilogram/minute for 30 minutes) with and without the endothelin type-A receptor antagonist, ABT 627(10 nanogram/kilogram/minute for 30 minutes), in rats pretreated with enalapril (250 milligram/Liter for one week) to normalize the endogenous renin angiotensin system. Endothelin type-A receptor blockade reduced angiotensin II-mediated increases in blood pressure in male control and male growth-restricted rats. Endothelin type-A receptor blockade also abolished hyper-responsiveness to acute angiotensin II in male growth-restricted rats. Yet, blood pressure remained significantly elevated above baseline following endothelin type-A receptor blockade suggesting that factors in addition to endothelin contribute to the basic angiotensin II-induced pressor response in male rats. We also determined sex-specific effects of endothelin on acute angiotensin II-mediated hemodynamic responses. Endothelin type-A receptor blockade did not reduce acute angiotensin II-mediated increases in blood pressure in female control or growth-restricted rats, intact or ovariectomized. Thus, these data suggest that endothelin type-A receptor blockade contributes to hypersensitivity to acute angiotensin II in male growth-restricted rats and further supports the sex-specific effect of endothelin on blood pressure. PMID:26459423

Activation of P2Y6 Receptors Facilitates Nonneuronal Adenosine Triphosphate and Acetylcholine Release from Urothelium with the Lamina Propria of Men with Bladder Outlet Obstruction.

PubMed

Silva, Isabel; Ferreirinha, Fátima; Magalhães-Cardoso, Maria Teresa; Silva-Ramos, Miguel; Correia-de-Sá, Paulo

2015-10-01

Deregulation of purinergic bladder signaling may contribute to persistent detrusor overactivity in patients with bladder outlet obstruction. Activation of uridine diphosphate sensitive P2Y6 receptors increases voiding frequency in rats indirectly by releasing adenosine triphosphate from the urothelium. To our knowledge this mechanism has never been tested in the human bladder. We examined the role of the uridine diphosphate sensitive P2Y6 receptor on tetrodotoxin insensitive nonneuronal adenosine triphosphate and [(3)H]acetylcholine release from the human urothelium with the lamina propria of control organ donors and patients with benign prostatic hyperplasia. The adenosine triphosphate-to-[(3)H]acetylcholine ratio was fivefold higher in mucosal urothelium/lamina propria strips from benign prostatic hyperplasia patients than control men. The selective P2Y6 receptor agonist PSB0474 (100 nM) augmented by a similar amount adenosine triphosphate and [(3)H]acetylcholine release from mucosal urothelium/lamina propria strips from both groups of individuals. The facilitatory effect of PSB0474 was prevented by MRS2578 (50 nM) and by carbenoxolone (10 μM), which block P2Y6 receptor and pannexin-1 hemichannels, respectively. Blockade of P2X3 (and/or P2X2/3) receptors with A317491 (100 nM) also attenuated release facilitation by PSB0474 in control men but not in patients with benign prostatic hyperplasia. Immunolocalization studies showed that P2Y6, P2X2 and P2X3 receptors were present in choline acetyltransferase positive urothelial cells. In contrast to P2Y6 staining, choline acetyltransferase, P2X2 and P2X3 immunoreactivity decreased in the urothelium of benign prostatic hyperplasia patients. Activation of P2Y6 receptor amplifies mucosal adenosine triphosphate release underlying bladder overactivity in patients with benign prostatic hyperplasia. Therefore, we propose selective P2Y6 receptor blockade as a novel therapeutic strategy to control persistent storage symptoms in obstructed patients. Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Regulation of Fear Extinction in the Basolateral Amygdala by Dopamine D2 Receptors Accompanied by Altered GluR1, GluR1-Ser845 and NR2B Levels.

PubMed

Shi, Yan-Wei; Fan, Bu-Fang; Xue, Li; Wen, Jia-Ling; Zhao, Hu

2017-01-01

The amygdala, a critical structure for both Pavlovian fear conditioning and fear extinction, receives sparse but comprehensive dopamine innervation and contains dopamine D1 and D2 receptors. Fear extinction, which involves learning to suppress the expression of a previously learned fear, appears to require the dopaminergic system. The specific roles of D2 receptors in mediating associative learning underlying fear extinction require further study. Intra-basolateral amygdala (BLA) infusions of a D2 receptor agonist, quinpirole, and a D2 receptor antagonist, sulpiride, prior to fear extinction and extinction retention were tested 24 h after fear extinction training for long-term memory (LTM). LTM was facilitated by quinpirole and attenuated by sulpiride. In addition, A-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor glutamate receptor 1 (GluR1) subunit, GluR1 phospho-Ser845, and N -methyl-D-aspartic acid receptor NR2B subunit levels in the BLA were generally increased by quinpirole and down-regulated by sulpiride. The present study suggests that activation of D2 receptors facilitates fear extinction and that blockade of D2 receptors impairs fear extinction, accompanied by changes in GluR1, GluR1-Ser845 and NR2B levels in the amygdala.

Cocaine Disrupts Histamine H3 Receptor Modulation of Dopamine D1 Receptor Signaling: σ1-D1-H3 Receptor Complexes as Key Targets for Reducing Cocaine's Effects

PubMed Central

Moreno, Estefanía; Moreno-Delgado, David; Navarro, Gemma; Hoffmann, Hanne M.; Fuentes, Silvia; Rosell-Vilar, Santi; Gasperini, Paola; Rodríguez-Ruiz, Mar; Medrano, Mireia; Mallol, Josefa; Cortés, Antoni; Casadó, Vicent; Lluís, Carme; Ferré, Sergi; Ortiz, Jordi; Canela, Enric

2014-01-01

The general effects of cocaine are not well understood at the molecular level. What is known is that the dopamine D1 receptor plays an important role. Here we show that a key mechanism may be cocaine's blockade of the histamine H3 receptor-mediated inhibition of D1 receptor function. This blockade requires the σ1 receptor and occurs upon cocaine binding to σ1-D1-H3 receptor complexes. The cocaine-mediated disruption leaves an uninhibited D1 receptor that activates Gs, freely recruits β-arrestin, increases p-ERK 1/2 levels, and induces cell death when over activated. Using in vitro assays with transfected cells and in ex vivo experiments using both rats acutely treated or self-administered with cocaine along with mice depleted of σ1 receptor, we show that blockade of σ1 receptor by an antagonist restores the protective H3 receptor-mediated brake on D1 receptor signaling and prevents the cell death from elevated D1 receptor signaling. These findings suggest that a combination therapy of σ1R antagonists with H3 receptor agonists could serve to reduce some effects of cocaine. PMID:24599455

In vitro contractile effects of neurokinin receptor blockade in the human ureter.

PubMed

Nakada, S Y; Jerde, T J; Bjorling, D E; Saban, R

2001-10-01

We identified the predominance of neurokinin-2 receptors and evaluated the inhibition of spontaneous contraction via the blockade of neurokinin-2 receptors in human ureteral segments. Excess ureteral segments from human subjects undergoing donor nephrectomy or reconstructive procedures were suspended in tissue baths containing Krebs buffer. After spontaneous contractions were recorded, tissues were incubated with 1 microM. solutions of phosphoramidon and captopril (to inhibit peptide degradation) and either the neurokinin-1 receptor antagonist CP 99,994, the neurokinin-2 receptor antagonist SR 48,968, the neurokinin-3 receptor antagonist SR 142,801 or dimethyl sulfoxide (control) for 1 hour. Contraction magnitude and frequency were again recorded and compared with spontaneous levels. Concentration-response curves to the tachykinins substance P, and neurokinins A and B were determined in the presence and absence of antagonists. Neurokinin A increased contractility at lower concentrations than substance P or neurokinin B (p <0.013). Neurokinin-2 receptor blockade produced a 100-fold rightward shift of the concentration-response curves (p <0.013), while neurokinins 1 and 3 receptor blockade had no effect. SR 48,968 significantly reduced contractility during the 1-hour incubation period, causing a 97% reduction in spontaneous rates compared with a 29% reduction in control tissues. CP 99,994 and SR 142,801 had no significant effect. Neurokinin-2 is the predominant receptor subtype responsible for tachykinin induced contraction of human ureteral smooth muscle. In vitro treatment with the neurokinin-2 antagonist SR 48,968 reduces the spontaneous contraction rate by 97% in vitro. Neurokinin-2 receptor antagonists may have clinical applications for ureteral disease.

Effects of ionotropic glutamate receptor antagonists on rat dural artery diameter in an intravital microscopy model.

PubMed

Chan, K Y; Gupta, S; de Vries, R; Danser, A H J; Villalón, C M; Muñoz-Islas, E; Maassenvandenbrink, A

2010-07-01

During migraine, trigeminal nerves may release calcitonin gene-related peptide (CGRP), inducing cranial vasodilatation and central nociception; hence, trigeminal inhibition or blockade of craniovascular CGRP receptors may prevent this vasodilatation and abort migraine headache. Several preclinical studies have shown that glutamate receptor antagonists affect the pathophysiology of migraine. This study investigated whether antagonists of NMDA (ketamine and MK801), AMPA (GYKI52466) and kainate (LY466195) glutamate receptors affected dural vasodilatation induced by alpha-CGRP, capsaicin and periarterial electrical stimulation in rats, using intravital microscopy. Male Sprague-Dawley rats were anaesthetized and the overlying bone was thinned to visualize the dural artery. Then, vasodilator responses to exogenous (i.v. alpha-CGRP) and endogenous (released by i.v. capsaicin and periarterial electrical stimulation) CGRP were elicited in the absence or presence of the above antagonists. alpha-CGRP, capsaicin and periarterial electrical stimulation increased dural artery diameter. Ketamine and MK801 inhibited the vasodilator responses to capsaicin and electrical stimulation, while only ketamine attenuated those to alpha-CGRP. In contrast, GYKI52466 only attenuated the vasodilatation to exogenous alpha-CGRP, while LY466195 did not affect the vasodilator responses to endogenous or exogenous CGRP. Although GYKI52466 has not been tested clinically, our data suggest that it would not inhibit migraine via vascular mechanisms. Similarly, the antimigraine efficacy of LY466195 seems unrelated to vascular CGRP-mediated pathways and/or receptors. In contrast, the cranial vascular effects of ketamine and MK801 may represent a therapeutic mechanism, although the same mechanism might contribute, peripherally, to cardiovascular side effects.

Cellular and behavioural profile of the novel, selective neurokinin1 receptor antagonist, vestipitant: a comparison to other agents.

PubMed

Brocco, Mauricette; Dekeyne, Anne; Mannoury la Cour, Clotilde; Touzard, Manuelle; Girardon, Sylvie; Veiga, Sylvie; de Nanteuil, Guillaume; deJong, Trynke R; Olivier, Berend; Millan, Mark J

2008-10-01

This study characterized the novel neurokinin (NK)(1) antagonist, vestipitant, under clinical evaluation for treatment of anxiety and depression. Vestipitant possessed high affinity for human NK(1) receptors (pK(i), 9.4), and potently blocked Substance P-mediated phosphorylation of Extracellular-Regulated-Kinase. In vivo, it occupied central NK(1) receptors in gerbils (Inhibitory Dose(50), 0.11 mg/kg). At similar doses, it abrogated nociception elicited by formalin in gerbils, and blocked foot-tapping and locomotion elicited by the NK(1) agonist, GR73632, in gerbils and guinea pigs, respectively. Further, vestipitant attenuated fear-induced foot-tapping in gerbils, separation-induced distress-vocalizations in guinea pigs, marble-burying behaviour in mice, and displayed anxiolytic actions in Vogel conflict and fear-induced ultrasonic vocalization procedures in rats. These actions were mimicked by CP99,994, L733,060 and GR205,171 which acted stereoselectively vs its less active isomer, GR226,206. In conclusion, vestipitant is a potent NK(1) receptor antagonist: its actions support the utility of NK(1) receptor blockade in the alleviation of anxiety and, possibly, depression.

Effects of the NMDA receptor antagonist, D-CPPene, on sensitization to the operant decrement produced by naloxone in morphine-treated rats.

PubMed

Bespalov, A Y; Medvedev, I O; Sukhotina, I A; Zvartau, E E

2001-04-01

Sensitization to the rate-decreasing effects of opioid antagonists induced by acute pretreatment with opioid agonists has been suggested to reflect initial changes in opioid systems that underlie physical dependence. Glutamate receptors are implicated in the development and expression of opioid dependence, and antagonists acting at the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors have been shown repeatedly to attenuate the severity of opioid withdrawal. The present study evaluated the ability of a competitive NMDA receptor antagonist, D-CPPene (SDZ EAA 494; 3-(2-carboxypiperazin-4-yl)-1-propenyl-1-phosphonic acid), to affect morphine-induced sensitization to naloxone in rats trained to lever-press on a multiple-trial, fixed-ratio 10 schedule of food reinforcement. D-CPPene (0.3-3 mg/kg) was administered either 4 h or 30 min prior to the test session. Morphine (10 mg/kg) or its vehicle was administered 4 h before naloxone challenge (0.3-3 mg/kg). D-CPPene failed to prevent morphine-induced potentiation of the naloxone-produced decrement in operant performance. Thus, these results suggest that agonist-induced sensitization to behavioral effects of opioid antagonists may be insensitive to NMDA receptor blockade.

8-OH-DPAT abolishes the pulmonary C-fiber-mediated apneic response to fentanyl largely via acting on 5HT1A receptors in the nucleus tractus solitarius

PubMed Central

Zhuang, Jianguo; Zhang, Zhenxiong; Zhang, Cancan

2012-01-01

Intravenous bolus injection of morphine causes a vagal-mediated brief apnea (∼3 s), while continuous injection, via action upon central μ-opioid receptor (MOR), arrests ventilation (>20 s) that is eliminated by stimulating central 5-hydroxytryptamine 1A receptors (5HT1ARs). Bronchopulmonary C-fibers (PCFs) are essential for triggering a brief apnea, and their afferents terminate at the caudomedial region of the nucleus tractus solitarius (mNTS) that densely expresses 5HT1ARs. Thus we asked whether the vagal-mediated apneic response to MOR agonists was PCF dependent, and if so, whether this apnea was abolished by systemic administration of 8-hydroxy-2-(di-n-propylamino)tetral (8-OH-DPAT) largely through action upon mNTS 5HT1ARs. Right atrial bolus injection of fentanyl (5.0 μg/kg, a MOR agonist) was performed in the anesthetized and spontaneously breathing rats before and after: 1) selective blockade of PCFs' conduction and subsequent bivagotomy; 2) intravenous administration of 5HT1AR agonist 8-OH-DPAT; 3) intra-mNTS injection of 8-OH-DPAT; and 4) intra-mNTS injection of 5HT1AR antagonist WAY-100635 followed by 8-OH-DPAT (iv). We found the following: First, fentanyl evoked an immediate apnea (2.5 ± 0.4 s, ∼6-fold longer than the baseline expiratory duration, TE), which was abolished by either blocking PCFs' conduction or bivagotomy. Second, this apnea was prevented by systemic 8-OH-DPAT challenge. Third, intra-mNTS injection of 8-OH-DPAT greatly attenuated the apnea by 64%. Finally, intra-mNTS microinjection of WAY-100635 significantly attenuated (58%) the apneic blockade by 8-OH-DPAT (iv). We conclude that the vagal-mediated apneic response to MOR activation depends on PCFs, which is fully antagonized by systemic 8-OH-DPAT challenge largely via acting on mNTS 5HT1ARs. PMID:22696579

The adenosine A2A antagonist MSX-3 reverses the effort-related effects of dopamine blockade: differential interaction with D1 and D2 family antagonists

PubMed Central

Worden, Lila T.; Shahriari, Mona; Farrar, Andrew M.; Sink, Kelly S.; Hockemeyer, Jörg; Müller, Christa E.

2010-01-01

Rationale Brain dopamine (DA) participates in the modulation of instrumental behavior, including aspects of behavioral activation and effort-related choice behavior. Rats with impaired DA transmission reallocate their behavior away from food-seeking behaviors that have high response requirements, and instead select less effortful alternatives. Although accumbens DA is considered a critical component of the brain circuitry regulating effort-related choice behavior, emerging evidence demonstrates a role for adenosine A2A receptors. Objective Adenosine A2A receptor antagonism has been shown to reverse the effects of DA antagonism. The present experiments were conducted to determine if this effect was dependent upon the subtype of DA receptor that was antagonized to produce the changes in effort-related choice. Materials and methods The adenosine A2A receptor antagonist MSX-3 (0.5–2.0 mg/kg IP) was assessed for its ability to reverse the effects of the D1 family antagonist SCH39166 (ecopipam; 0.2 mg/kg IP) and the D2 family antagonist eticlopride (0.08 mg/kg IP), using a concurrent lever pressing/chow feeding procedure. Results MSX-3 produced a substantial dose-related reversal of the effects of eticlopride on lever pressing and chow intake. At the highest dose of MSX-3, there was a complete reversal of the effects of eticlopride on lever pressing. In contrast, MSX-3 produced only a minimal attenuation of the effects of SCH39166, as measured by regression and effect size analyses. Conclusions The greater ability of MSX-3 to reverse the effects of D2 vs. D1 blockade may be related to the colocalization of D2 and adenosine A2A receptors on the same population of striatal neurons. PMID:19048234

Comparison of the phenotype of NK1R-/- mice with pharmacological blockade of the substance P (NK1 ) receptor in assays for antidepressant and anxiolytic drugs.

PubMed

Rupniak, N M; Carlson, E J; Webb, J K; Harrison, T; Porsolt, R D; Roux, S; de Felipe, C; Hunt, S P; Oates, B; Wheeldon, A

2001-11-01

The phenotype of NK1R-/- mice was compared with that of acute pharmacological blockade of the tachykinin NK1 receptor on sensorimotor function and in assays relevant to depressive illness and anxiety. The dose range for L-760735 and GR205171 that was associated with functional blockade of central NK1 receptors in the target species was established by antagonism of the behavioural effects of intracerebroventricular NK1 agonist challenge in gerbils, mice and rats. The caudal grooming and scratching response to GR73632 was absent in NK1R-/- mice, confirming that the receptor had been genetically ablated. There was no evidence of sedation or motor impairment in NK1R-/- mice or following administration of L-760735 to gerbils, even at doses in excess of those required for central NK1 receptor occupancy. In the resident-intruder and forced swim test, the behaviour of NK1R-/- mice, or animals treated acutely with L-760735 or GR205171, resembled that seen with the clinically used antidepressant drug fluoxetine. However, the effects of GR205171 were not clearly enantioselective in mice. In contrast, although NK1R-/- mice also exhibited an increase in the duration of struggle behaviour in the tail suspension test, this was not observed following pharmacological blockade with L-760735 in gerbils or GR205171 in mice, suggesting that this may reflect a developmental alteration in the knockout mouse. There was no effect of NK1 receptor blockade with L-760735 in guinea-pigs or GR205171 in rats, or deletion of the NK1 receptor in mice, on behaviour in the elevated plus-maze test for anxiolytic activity. These findings extend previous observations on the phenotype of the NK1R-/- mouse and establish a broadly similar profile following acute pharmacological blockade of the receptor. These studies also serve to underscore the limitations of currently available antagonists that are suitable for use in rat and mouse behavioural assays.

Peptidergic modulation of synaptic transmission in the parabrachial nucleus in vitro: importance of degradative enzymes in regulating synaptic efficacy.

PubMed

Saleh, T M; Kombian, S B; Zidichouski, J A; Pittman, Q J

1996-10-01

This study examined the effects of substance P (SP) and calcitonin gene-related peptide (CGRP) on synaptic transmission in a pontine slice containing the parabrachial nucleus (PBN). Stimulation of the ventral, external lateral portion of the PBN elicited glutamate-mediated EPSCs in cells recorded using the nystatin perforated-patch recording technique in the external lateral, external medial, and central lateral subnuclei of the PBN. Bath application of SP or CGRP dose-dependently and reversibly attenuated the evoked EPSC. The attenuation of the EPSC induced by both of these peptides was not accompanied by changes in input resistance of PBN cells over a wide voltage range, nor did these peptides alter the inward current induced by a brief bath application of AMPA. The combined application of subthreshold concentrations of these peptides revealed a synergistic interaction in reducing the evoked EPSC. The substance P neurokinin-1 receptor antagonist CGP49823 completely and reversibly blocked both the SP- and the CGRP-induced attenuation of the EPSC. However, the rat CGRP receptor antagonist human-CGRP8-37 did not block the actions of CGRP or SP on the EPSC. Using a metabolically stable analog of SP, SP (5-11), or an endopeptidase inhibitor, phosphoramidon, we were able to demonstrate that CGRP enhances the SP effect by inhibiting an SP endopeptidase. Application of phosphoramidon also revealed an endogenous SP "tone" apparently made effective by blockade of the endopeptidase. These results suggest that SP (and CGRP indirectly through an inhibition of the SP endopeptidase) acts on presynaptic NK-1 receptors to cause an inhibition of excitatory transmission in the PBN. These results indicate an important role of endopeptidases in regulating synaptic modulation by peptides.

Effects of NMDA receptor blockade during the early development period on the retest performance of adult Wistar rats in the elevated plus maze.

PubMed

Kocahan, Sayad; Akillioglu, Kubra

2013-07-01

The elevated plus maze (EPM) is an animal model of anxiety used to test the effects of anxioselective drugs. The loss of the anxiolytic effect of drugs during the second exposure to the EPM is called the "one trial tolerance" (OTT) phenomenon. The present study was designed to investigate the relationship between the OTT phenomenon and N-methyl-D-aspartate (NMDA) receptor blockade in the early developmental period of rats. NMDA receptor blockade was accomplished using MK-801 treatment given between postnatal days 20-30. Beginning on postnatal day 20, the rats were subcutaneously injected with MK-801 twice a day at the nape of the neck for a period of 10 days (0.25 mg/kg). Increased open arm exploration was observed in MK-801-treated rats during trial 1 (p = 0.001) and trial 2 (p = 0.003). The rats spent less time in the closed arms as compared to the saline animals in trial 1 (p = 0.006), and this time decreased further in trial 2 (p = 0.02). The fecal boli of the MK-801 group was decreased in trial 1 as compared to the saline group (p = 0.01), but was not significantly different in trial 2 (p = 0.08). In conclusion, NMDA receptor blockade using MK-801 produced an anxiolytic-like effect in trials 1 and 2. Furthermore, OTT was not affected by NMDA receptor blockade.

Loganin enhances long-term potentiation and recovers scopolamine-induced learning and memory impairments.

PubMed

Hwang, Eun-Sang; Kim, Hyun-Bum; Lee, Seok; Kim, Min-Ji; Lee, Sung-Ok; Han, Seung-Moo; Maeng, Sungho; Park, Ji-Ho

2017-03-15

Although the incidence rate of dementia is rapidly growing in the aged population, therapeutic and preventive reagents are still suboptimal. Various model systems are used for the development of such reagents in which scopolamine is one of the favorable pharmacological tools widely applied. Loganin is a major iridoid glycoside obtained from Corni fructus (Cornusofficinalis et Zucc) and demonstrated to have anti-inflammatory, anti-tumor and osteoporosis prevention effects. It has also been found to attenuate Aβ-induced inflammatory reactions and ameliorate memory deficits induced by scopolamine. However, there has been limited information available on how loganin affects learning and memory both electrophysiologically and behaviorally. To assess its effect on learning and memory, we investigated the influence of acute loganin administration on long-term potentiation (LTP) using organotypic cultured hippocampal tissues. In addition, we measured the effects of loganin on the behavior performance related to avoidance memory, short-term spatial navigation memory and long-term spatial learning and memory in the passive avoidance, Y-maze, and Morris water maze learning paradigms, respectively. Loganin dose-dependently increased the total activity of fEPSP after high frequency stimulation and attenuated scopolamine-induced blockade of fEPSP in the hippocampal CA1 area. In accordance with these findings, loganin behaviorally attenuated scopolamine-induced shortening of step-through latency in the passive avoidance test, reduced the percent alternation in the Y-maze, and increased memory retention in the Morris water maze test. These results indicate that loganin can effectively block cholinergic muscarinic receptor blockade -induced deterioration of LTP and memory related behavioral performance. Based on these findings, loganin may aid in the prevention and treatment of Alzheimer's disease and learning and memory-deficit disorders in the future. Copyright © 2017 Elsevier Inc. All rights reserved.

Role of adenosine A{sub 2A} receptor signaling in the nicotine-evoked attenuation of reflex cardiac sympathetic control

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Mas, Mahmoud M., E-mail: mahelm@hotmail.com; El-gowilly, Sahar M.; Fouda, Mohamed A.

Baroreflex dysfunction contributes to increased cardiovascular risk in cigarette smokers. Given the importance of adenosinergic pathways in baroreflex control, the hypothesis was tested that defective central adenosinergic modulation of cardiac autonomic activity mediates the nicotine-baroreflex interaction. Baroreflex curves relating changes in heart rate (HR) to increases or decreases in blood pressure (BP) evoked by i.v. doses (1-16 {mu}g/kg) of phenylephrine (PE) and sodium nitroprusside (SNP), respectively, were constructed in conscious rats; slopes of the curves were taken as measures of baroreflex sensitivity (BRS). Nicotine (25 and 100 {mu}g/kg i.v.) dose-dependently reduced BRS{sub SNP} in contrast to no effect on BRS{submore » PE}. BRS{sub SNP} was also attenuated after intracisternal (i.c.) administration of nicotine. Similar reductions in BRS{sub SNP} were observed in rats pretreated with atropine or propranolol. The combined treatment with nicotine and atropine produced additive inhibitory effects on BRS, an effect that was not demonstrated upon concurrent exposure to nicotine and propranolol. BRS{sub SNP} was reduced in preparations treated with i.c. 8-phenyltheophylline (8-PT, nonselective adenosine receptor antagonist), 8-(3-Chlorostyryl) caffeine (CSC, A{sub 2A} antagonist), or VUF5574 (A{sub 3} antagonist). In contrast, BRS{sub SNP} was preserved after blockade of A{sub 1} (DPCPX) or A{sub 2B} (alloxazine) receptors or inhibition of adenosine uptake by dipyridamole. CSC or 8-PT abrogated the BRS{sub SNP} depressant effect of nicotine whereas other adenosinergic antagonists were without effect. Together, nicotine preferentially impairs reflex tachycardia via disruption of adenosine A{sub 2A} receptor-mediated facilitation of reflex cardiac sympathoexcitation. Clinically, the attenuation by nicotine of compensatory sympathoexcitation may be detrimental in conditions such as hypothalamic defense response, posture changes, and ventricular rhythms. - Research Highlights: > The role of central adenosinergic sites in the nicotine-baroreflex interaction was investigated. > Inhibition of reflex sympathoinhibition mediates the BRS depressant action of nicotine. > Nicotine preferentially impairs reflex tachycardia via disruption of adenosine A{sub 2A} signaling. > The attenuation by nicotine of reflex sympathetic activity is clinically important.« less

The NK1 Receptor Antagonist L822429 Reduces Heroin Reinforcement

PubMed Central

Barbier, Estelle; Vendruscolo, Leandro F; Schlosburg, Joel E; Edwards, Scott; Juergens, Nathan; Park, Paula E; Misra, Kaushik K; Cheng, Kejun; Rice, Kenner C; Schank, Jesse; Schulteis, Gery; Koob, George F; Heilig, Markus

2013-01-01

Genetic deletion of the neurokinin 1 receptor (NK1R) has been shown to decrease the reinforcing properties of opioids, but it is unknown whether pharmacological NK1R blockade has the same effect. Here, we examined the effect of L822429, a rat-specific NK1R antagonist, on the reinforcing properties of heroin in rats on short (1 h: ShA) or long (12 h: LgA) access to intravenous heroin self-administration. ShA produces heroin self-administration rates that are stable over time, whereas LgA leads to an escalation of heroin intake thought to model important dependence-related aspects of addiction. L822429 reduced heroin self-administration and the motivation to consume heroin, measured using a progressive-ratio schedule, in both ShA and LgA rats. L822429 also decreased anxiety-like behavior in both groups, measured on the elevated plus maze, but did not affect mechanical hypersensitivity observed in LgA rats. Expression of TacR1 (the gene encoding NK1R) was decreased in reward- and stress-related brain areas both in ShA and LgA rats compared with heroin-naïve rats, but did not differ between the two heroin-experienced groups. In contrast, passive exposure to heroin produced increases in TacR1 expression in the prefrontal cortex and nucleus accumbens. Taken together, these results show that pharmacological NK1R blockade attenuates heroin reinforcement. The observation that animals with ShA and LgA to heroin were similarly affected by L822429 indicates that the SP/NK1R system is not specifically involved in neuroadaptations that underlie escalation resulting from LgA self-administration. Instead, the NK1R antagonist appears to attenuate acute, positively reinforcing properties of heroin and may be useful as an adjunct to relapse prevention in detoxified opioid-dependent subjects. PMID:23303056

Epidermal growth factor receptor inhibitor PKI-166 governs cardiovascular protection without beneficial effects on the kidney in hypertensive 5/6 nephrectomized rats.

PubMed

Ulu, Nadir; Mulder, Gemma M; Vavrinec, Peter; Landheer, Sjoerd W; Duman-Dalkilic, Basak; Gurdal, Hakan; Goris, Maaike; Duin, Marry; van Dokkum, Richard P E; Buikema, Hendrik; van Goor, Harry; Henning, Robert H

2013-06-01

Transactivation of epidermal growth factor receptor (EGFR) signaling by G protein-coupled receptors has been implicated in several cardiovascular (CV) conditions, including hypertension, heart failure, and cardiac and vascular hypertrophy. However, the therapeutic potential of EGFR inhibition in these conditions is currently unknown. The main objective of the present study was to investigate cardiac, vascular, and renal effects of EGFR inhibition by 4-[4-[[(1R)-1-phenylethyl]amino]-7H-pyrrolo[2,3-d]pyrimidin-6-yl]phenol (PKI-166) in the hypertensive chronic kidney disease model. Rats underwent 5/6 nephrectomy (5/6Nx) and were treated with PKI-166, lisinopril or vehicle from week 6 after disease induction until week 12. Sham animals received either PKI-166 or vehicle. Treatment with PKI-166 did not affect the development of the characteristic renal features in 5/6Nx, including proteinuria, diminished creatinine clearance, and increased glomerulosclerosis, whereas these were attenuated by lisinopril. Despite absence of effects on progressive renal damage, PKI-166 attenuated the progression of hypertension and maintained cardiac function (left ventricle end-diastolic pressure) to a similar extent as lisinopril. Also, PKI-166 attenuated the increase in phosphorylated EGFR in the heart as induced by 5/6Nx. Moreover, PKI-166 and lisinopril restored the impaired contraction of isolated thoracic aortic rings to phenylephrine and angiotensin II and impaired myogenic constriction of small mesenteric arteries in 5/6Nx rats. Blockade of the EGFR displays a CV benefit independent of limiting the progression of renal injury. Our findings extend the evidence on EGFR signaling as a target in CV disorders.

Opioid Facilitation of β-Adrenergic Blockade: A New Pharmacological Condition?

PubMed Central

Vamecq, Joseph; Mention-Mulliez, Karine; Leclerc, Francis; Dobbelaere, Dries

2015-01-01

Recently, propranolol was suggested to prevent hyperlactatemia in a child with hypovolemic shock through β-adrenergic blockade. Though it is a known inhibitor of glycolysis, propranolol, outside this observation, has never been reported to fully protect against lactate overproduction. On the other hand, literature evidence exists for a cross-talk between β-adrenergic receptors (protein targets of propranolol) and δ-opioid receptor. In this literature context, it is hypothesized here that anti-diarrheic racecadotril (a pro-drug of thiorphan, an inhibitor of enkephalinases), which, in the cited observation, was co-administered with propranolol, might have facilitated the β-blocker-driven inhibition of glycolysis and resulting lactate production. The opioid-facilitated β-adrenergic blockade would be essentially additivity or even synergism putatively existing between antagonism of β-adrenergic receptors and agonism of δ-opioid receptor in lowering cellular cAMP and dependent functions. PMID:26426025

Loss of neutral endopeptidase activity contributes to neutrophil activation and cardiac dysfunction during chronic hypomagnesemia: Protection by substance P receptor blockade.

PubMed

Mak, I Tong; Chmielinska, Joanna J; Kramer, Jay H; Spurney, Christopher F; Weglicki, William B

2011-01-01

Hypomagnesemia (Hypo-Mg) in rodents leads to neurogenic inflammation associated with substance P (SP) elevations; neutral endopeptidase (NEP) is a principle cell surface proteolytic enzyme, which degrades SP. The effects of chronic Hypo-Mg on neutrophil NEP activity, cell activation and the associated cardiac dysfunction were examined. Male Sprague-Dawley rats (180 g) were fed Mg-sufficient or Mg-deficient (Hypo-Mg) diets for five weeks. Enriched blood neutrophils were isolated at the end of one, three and five weeks by step gradient centrifugation. NEP enzymatic activity decreased by 20% (P value was nonsignificant), 50% (P<0.025) and 57% (P<0.01), respectively, for week 1, 3 and 5 Hypo-Mg rats. In association, neutrophil basal superoxide (•O(2) (-))-generating activities were elevated: 30% at week 1 (P value was nonsignificant), and fourfold to sevenfold for weeks 3 to 5 (P<0.01). Maximal phorbol myristate acetate-stimulated •O(2) (-) production by Hypo-Mg neutrophils increased twofold at week 5. Also, plasma 8-isoprostane levels were elevated twofold to threefold, and red blood cell glutathione decreased by 50% (P<0.01) after three to five weeks of chronic Hypo-Mg. When Hypo-Mg rats were treated with the SP receptor blocker (L-703,606), neutrophil NEP activities were retained at 75% (week 3) and 77% (week 5) (P<0.05); activation of neutrophil •O(2) (-) and other oxidative indexes were also significantly (P<0.05) attenuated. After five weeks, histochemical (hematoxylin and eosin) staining of Hypo-Mg-treated rat ventricles revealed significant white blood cell infiltration, which was substantially reduced by L-703,606. Echocardiography after three weeks of Hypo-Mg only showed modest diastolic impairment, but five weeks resulted in significant (P<0.05) depression in both left ventricular systolic and diastolic functions; changes in these functional parameters were attenuated by L-703,606. NEP activity regulates neutrophil •O(2) (-) formation by controlling SP bioavailability. When oxidative inactivation of NEP is prevented by SP receptor blockade, partial protection is afforded against cardiac contractile dysfunction.

Loss of neutral endopeptidase activity contributes to neutrophil activation and cardiac dysfunction during chronic hypomagnesemia: Protection by substance P receptor blockade

PubMed Central

Mak, I Tong; Chmielinska, Joanna J; Kramer, Jay H; Spurney, Christopher F; Weglicki, William B

2011-01-01

BACKGROUND/OBJECTIVE: Hypomagnesemia (Hypo-Mg) in rodents leads to neurogenic inflammation associated with substance P (SP) elevations; neutral endopeptidase (NEP) is a principle cell surface proteolytic enzyme, which degrades SP. The effects of chronic Hypo-Mg on neutrophil NEP activity, cell activation and the associated cardiac dysfunction were examined. METHODS/RESULTS: Male Sprague-Dawley rats (180 g) were fed Mg-sufficient or Mg-deficient (Hypo-Mg) diets for five weeks. Enriched blood neutrophils were isolated at the end of one, three and five weeks by step gradient centrifugation. NEP enzymatic activity decreased by 20% (P value was nonsignificant), 50% (P<0.025) and 57% (P<0.01), respectively, for week 1, 3 and 5 Hypo-Mg rats. In association, neutrophil basal superoxide (•O2−)-generating activities were elevated: 30% at week 1 (P value was nonsignificant), and fourfold to sevenfold for weeks 3 to 5 (P<0.01). Maximal phorbol myristate acetate-stimulated •O2− production by Hypo-Mg neutrophils increased twofold at week 5. Also, plasma 8-isoprostane levels were elevated twofold to threefold, and red blood cell glutathione decreased by 50% (P<0.01) after three to five weeks of chronic Hypo-Mg. When Hypo-Mg rats were treated with the SP receptor blocker (L-703,606), neutrophil NEP activities were retained at 75% (week 3) and 77% (week 5) (P<0.05); activation of neutrophil •O2− and other oxidative indexes were also significantly (P<0.05) attenuated. After five weeks, histochemical (hematoxylin and eosin) staining of Hypo-Mg-treated rat ventricles revealed significant white blood cell infiltration, which was substantially reduced by L-703,606. Echocardiography after three weeks of Hypo-Mg only showed modest diastolic impairment, but five weeks resulted in significant (P<0.05) depression in both left ventricular systolic and diastolic functions; changes in these functional parameters were attenuated by L-703,606. CONCLUSION: NEP activity regulates neutrophil •O2− formation by controlling SP bioavailability. When oxidative inactivation of NEP is prevented by SP receptor blockade, partial protection is afforded against cardiac contractile dysfunction. PMID:22131854

Plasticity of cardiovascular function in snapping turtle embryos (Chelydra serpentina): chronic hypoxia alters autonomic regulation and gene expression.

PubMed

Eme, John; Rhen, Turk; Tate, Kevin B; Gruchalla, Kathryn; Kohl, Zachary F; Slay, Christopher E; Crossley, Dane A

2013-06-01

Reptile embryos tolerate large decreases in the concentration of ambient oxygen. However, we do not fully understand the mechanisms that underlie embryonic cardiovascular short- or long-term responses to hypoxia in most species. We therefore measured cardiac growth and function in snapping turtle embryos incubated under normoxic (N21; 21% O₂) or chronic hypoxic conditions (H10; 10% O₂). We determined heart rate (fH) and mean arterial pressure (Pm) in acute normoxic (21% O₂) and acute hypoxic (10% O₂) conditions, as well as embryonic responses to cholinergic, adrenergic, and ganglionic pharmacological blockade. Compared with N21 embryos, chronic H10 embryos had smaller bodies and relatively larger hearts and were hypotensive, tachycardic, and following autonomic neural blockade showed reduced intrinsic fH at 90% of incubation. Unlike other reptile embryos, cholinergic and ganglionic receptor blockade both increased fH. β-Adrenergic receptor blockade with propranolol decreased fH, and α-adrenergic blockade with phentolamine decreased Pm. We also measured cardiac mRNA expression. Cholinergic tone was reduced in H10 embryos, but cholinergic receptor (Chrm2) mRNA levels were unchanged. However, expression of adrenergic receptor mRNA (Adrb1, Adra1a, Adra2c) and growth factor mRNA (Igf1, Igf2, Igf2r, Pdgfb) was lowered in H10 embryos. Hypoxia altered the balance between cholinergic receptors, α-adrenoreceptor and β-adrenoreceptor function, which was reflected in altered intrinsic fH and adrenergic receptor mRNA levels. This is the first study to link gene expression with morphological and cardioregulatory plasticity in a developing reptile embryo.

Chronic suppression of μ-opioid receptor signaling in the nucleus accumbens attenuates development of diet-induced obesity in rats.

PubMed

Lenard, N R; Zheng, H; Berthoud, H-R

2010-06-01

To test the hypothesis that micro-opioid receptor signaling in the nucleus accumbens contributes to hedonic (over)eating and obesity. To investigate the effects of chronic micro-opioid antagonism in the nucleus accumbens core or shell on intake of a palatable diet, and the development of diet-induced obesity in rats. Chronic blockade of micro-opioid receptor signaling in the nucleus accumbens core or shell was achieved by means of repeated injections (every 4-5 days) of the irreversible receptor antagonist beta-funaltrexamine (BFNA) over 3-5 weeks. The diet consisted of either a choice of high-fat chow, chocolate-flavored Ensure and regular chow (each nutritionally complete) or regular chow only. Intake of each food item, body weight and body fat mass were monitored throughout the study. The BFNA injections aimed at either the core or shell of the nucleus accumbens resulted in significantly attenuated intake of palatable diet, body weight gain and fat accretion, compared with vehicle control injections. The injection of BFNA in the core did not significantly change these parameters in chow-fed control rats. The injection of BFNA in the core and shell differentially affected intake of the two palatable food items: in the core, BFNA significantly reduced the intake of high-fat, but not of Ensure, whereas in the shell, it significantly reduced the intake of Ensure, but not of high-fat, compared with vehicle treatment. Endogenous micro-opioid receptor signaling in the nucleus accumbens core and shell is necessary for palatable diet-induced hyperphagia and obesity to fully develop in rats. Sweet and non-sweet fatty foods may be differentially processed in subcomponents of the ventral striatum.

Primary sensory neuron-specific interference of TRPV1 signaling by adeno-associated virus-encoded TRPV1 peptide aptamer attenuates neuropathic pain

PubMed Central

Xiang, Hongfei; Liu, Zhen; Wang, Fei; Xu, Hao; Roberts, Christopher; Fischer, Gregory; Stucky, Cheryl L; Dean, Caron; Pan, Bin; Hogan, Quinn H; Yu, Hongwei

2017-01-01

Background TRPV1 (transient receptor potential vanilloid subfamily member 1) is a pain signaling channel highly expressed in primary sensory neurons. Attempts for analgesia by systemic TRPV1 blockade produce undesirable side effects, such as hyperthermia and impaired heat pain sensation. One approach for TRPV1 analgesia is to target TRPV1 along the peripheral sensory pathway. Results For functional blockade of TRPV1 signaling, we constructed an adeno-associated virus (AAV) vector expressing a recombinant TRPV1 interfering peptide aptamer, derived from a 38mer tetrameric assembly domain (TAD), encompassing residues 735 to 772 of rat TRPV1, fused to the C-terminus of enhanced green fluorescent protein (EGFP). AAV-targeted sensory neurons expressing EGFP-TAD after vector injection into the dorsal root ganglia (DRG) revealed decreased inward calcium current and diminished intracellular calcium accumulation in response to capsaicin, compared to neurons of naïve or expressing EGFP alone. To examine the potential for treating neuropathic pain, AAV-EGFP-TAD was injected into fourth and fifth lumbar (L) DRGs of rats subjected to neuropathic pain by tibial nerve injury (TNI). Results showed that AAV-directed selective expression of EGFP-TAD in L4/L5 DRG neuron somata, and their peripheral and central axonal projections can limit TNI-induced neuropathic pain behavior, including hypersensitivity to heat and, to a less extent, mechanical stimulation. Conclusion Selective inhibition of TRPV1 activity in primary sensory neurons by DRG delivery of AAV-encoded analgesic interfering peptide aptamers is efficacious in attenuation of neuropathic pain. With further improvements of vector constructs and in vivo application, this approach might have the potential to develop as an alternative gene therapy strategy to treat chronic pain, especially heat hypersensitivity, without complications due to systemic TRPV1 blockade. PMID:28604222

Interactions between ifenprodil and dizocilpine on mouse behaviour in models of anxiety and working memory.

PubMed

Fraser, C M; Cooke, M J; Fisher, A; Thompson, I D; Stone, T W

1996-11-01

The N-methyl-D-aspartate (NMDA) receptor polyamine site antagonist, ifenprodil, had no effect on spontaneous alteration or locomotor activity in the Y-maze when given alone. The NMDA receptor/ion channel blocker, dizocilpine, induced a deficit in spontaneous alteration, but when ifenprodil was co-administered with dizocilpine, it showed a strong tendency to attenuate the dizocilpine-induced deficit. In the plus-maze, ifenprodil had an anxiolytic profile which was accompanied by an increase in locomotion. Dizocilpine had an anxiolytic profile in this model and increased locomotor activity. When co-administered with dizocilpine, ifenprodil reduced both the anxiolytic and locomotor effects of dizocilpine. When co-administered with ifenprodil, cyclopentyladenosine (CPA) and 1,3-dipropyl-8-cyclopentylxanthine (CPX) reduced the anxiolytic effect of ifenprodil. CPA and CPX in combination did not reverse the anxiolytic effect of ifenpropil. It is concluded that NMDA antagonists with different sites of action can show distinct behavioural profiles, with dizocilpine but not ifenprodil inducing a deficit in working memory, while both are anxiolytic. Blockade of NMDA receptors by ifenprodil, however, can preclude any response to dizocilpine. The anxiolytic activity of ifenprodil may involve the release of purines acting at adenosine receptors.

Effect of K+ATP channel and adenosine receptor blockade during rest and exercise in congestive heart failure.

PubMed

Traverse, Jay H; Chen, YingJie; Hou, MingXiao; Li, Yunfang; Bache, Robert J

2007-06-08

K(+)(ATP) channels are important metabolic regulators of coronary blood flow (CBF) that are activated in the setting of reduced levels of ATP or perfusion pressure. In the normal heart, blockade of K(+)(ATP) channels results in a approximately 20% reduction in resting CBF but does not impair the increase in CBF that occurs during exercise. In contrast, adenosine receptor blockade fails to alter CBF or myocardial oxygen consumption (MVO(2)) in the normal heart but contributes to the increase in CBF during exercise when vascular K(+)(ATP) channels are blocked. Congestive heart failure (CHF) is associated with a decrease in CBF that is matched to a decrease in MVO(2) suggesting downregulation of myocardial energy utilization. Because myocardial ATP levels and coronary perfusion pressure are reduced in CHF, this study was undertaken to examine the role of K(+)(ATP) channels and adenosine in dogs with pacing-induced CHF. Myocardial blood flow (MBF) and MVO(2) were measured during rest and treadmill exercise before and after K(+)(ATP) channel blockade with glibenclamide (50 microg/kg/min ic) or adenosine receptor blockade with 8-phenyltheophylline (8-PT; 5 mg/kg iv). Inhibition of K(+)(ATP) channels resulted in a decrease in CBF and MVO(2) at rest and during exercise without a change in the relationship between CBF and MVO(2). In contrast, adenosine receptor blockade caused a significant increase in CBF that occurred secondary to an increase of MVO(2). These findings demonstrate that coronary K(+)(ATP) channel activity contribute to the regulation of resting MBF in CHF, and that endogenous adenosine may act to inhibit MVO(2) in the failing heart.

Role of 5-HT5A receptors in the consolidation of memory.

PubMed

Gonzalez, Roberto; Chávez-Pascacio, Karla; Meneses, Alfredo

2013-09-01

5-HT5 receptor occurs in brain areas implicated in learning and memory. Hence, the effects (0.01-3.0 mg/kg) of SB-6995516 (a 5-HT5A receptor antagonist) in the associative learning task of autoshaping were studied. The results showed that post-training injection of SB-699551 decreased conditioned responses (CR) during short-term (STM; 1.5h; at 0.1mg/kg) and long-term memory (LTM; 24 h; at 3.0 mg/kg) relative to the vehicle animals. Moreover, considering that there are no selective 5-HT5A receptor agonists, next, diverse doses of the serotonin precursor l-tryptophan were studied during STM and LTM, showing that l-tryptophan (5-100mg/kg) facilitated performance, particularly at 50mg/kg. In interactions experiments, l-tryptophan (50 mg/kg) attenuated the impairment effect induced by SB-699551 (either 0.3 or 3.0 mg/kg). All together this evidence suggests that the blockade of 5-HT5A receptor appear to be able to impair STM and LTM (24 h), while its stimulation might facilitate it. Of course further investigation is necessary, meanly with selective 5-HT5A compounds are necessary. Copyright © 2013 Elsevier B.V. All rights reserved.

Attenuation of tolerance to opioid-induced antinociception and protection against morphine-induced decrease of neurofilament proteins by idazoxan and other I2-imidazoline ligands.

PubMed

Boronat, M A; Olmos, G; García-Sevilla, J A

1998-09-01

1. Agmatine, the proposed endogenous ligand for imidazoline receptors, has been shown to attenuate tolerance to morphine-induced antinociception (Kolesnikov el al., 1996). The main aim of this study was to assess if idazoxan, an alpha2-adrenoceptor antagonist that also interacts with imidazoline receptors, could also modulate opioid tolerance in rats and to establish which type of imidazoline receptors (or other receptors) are involved. 2. Antinociceptive responses to opioid drugs were determined by the tail-flick test. The acute administration of morphine (10 mg kg(-1), i.p., 30 min) or pentazocine (10 mg kg(-1), i.p., 30 min) resulted in marked increases in tail-flick latencies (TFLs). As expected, the initial antinociceptive response to the opiates was lost after chronic (13 days) treatment (tolerance). When idazoxan (10 mg kg(-1), i.p.) was given chronically 30 min before the opiates it completely prevented morphine tolerance and markedly attenuated tolerance to pentazocine (TFLs increased by 71-143% at day 13). Idazoxan alone did not modify TFLs. 3. The concurrent chronic administration (10 mg kg(-1), i.p., 13 days) of 2-BFI, LSL 60101, and LSL 61122 (valldemossine), selective and potent I2-imidazoline receptor ligands, and morphine (10 mg kg(-1), i.p.), also prevented or attenuated morphine tolerance (TFLs increased by 64 172% at day 13). This attenuation of morphine tolerance was still apparent six days after discontinuation of the chronic treatment with LSL 60101-morphine. The acute treatment with these drugs did not potentiate morphine-induced antinociception. These drugs alone did not modify TFLs. Together, these results indicated the specific involvement of I2-imidazoline receptors in the modulation of opioid tolerance. 4. The concurrent chronic (13 days) administration of RX821002 (10 mg kg(-1), i.p.) and RS-15385-197 (1 mg kg(-1), i.p.), selective alpha2-adrenoceptor antagonists, and morphine (10 mg kg(-1), i.p.), did not attenuate morphine tolerance. Similarly, the concurrent chronic treatment of moxonidine (1 mg kg(-1), i.p.), a mixed I(1)-imidazoline receptor and alpha2-adrenoceptor agonist, and morphine (10 mg kg(-1), i.p.), did not alter the development of tolerance to the opiate. These results discounted the involvement of alpha2-adrenoceptors and I(1)-imidazoline receptors in the modulatory effect of idazoxan on opioid tolerance. 5. Idazoxan and other imidazol(ine) drugs fully inhibited [3H]-(+)-MK-801 binding to N-methyl-D-aspartate (NMDA) receptors in the rat cerebral cortex with low potencies (Ki: 37-190 microM). The potencies of the imidazolines idazoxan, RX821002 and moxonidine were similar, indicating a lack of relationship between potency on NMDA receptors and ability to attenuate opioid tolerance. These results suggested that modulation of opioid tolerance by idazoxan is not related to NMDA receptors blockade. 6. Chronic treatment (13 days) with morphine (10 mg kg(-1), i.p.) was associated with a marked decrease (49%) in immunolabelled neurofilament proteins (NF-L) in the frontal cortex of morphine-tolerant rats, suggesting the induction of neuronal damage. Chronic treatment (13 days) with idazoxan (10 mg kg(-1)) and LSL 60101 (10 mg kg(-1)) did not modify the levels of NF-L proteins in brain. Interestingly, the concurrent chronic treatment (13 days) of idazoxan or LSL 60101 and morphine, completely reversed the morphine-induced decrease in NF-L immunoreactivity, suggesting a neuroprotective role for these drugs. 7. Together, the results indicate that chronic treatment with I2-imidazoline ligands attenuates the development of tolerance to opiate drugs and may induce neuroprotective effects on chronic opiate treatment. Moreover, these findings offer the I2-imidazoline ligands as promising therapeutic coadjuvants in the management of chronic pain with opiate drugs.

Attenuated EAN in TNF-α Deficient Mice Is Associated with an Altered Balance of M1/M2 Macrophages

PubMed Central

Zhang, Hong-Liang; Hassan, Mohammed Y.; Zheng, Xiang-Yu; Azimullah, Sheikh; Quezada, Hernan Concha; Amir, Naheed; Elwasila, Mohamed; Mix, Eilhard; Adem, Abdu; Zhu, Jie

2012-01-01

The role of tumor necrosis factor (TNF)-α and its receptors in neuroautoimmune and neuroinflammatory diseases has been controversial. On the basis of our previous studies, we hereby aimed to further clarify TNF-α’s mechanism of action and to explore the potential role of TNF-α receptor (TNFR)1 as a therapeutic target in experimental autoimmune neuritis (EAN). EAN was induced by immunization with P0 peptide 180–199 in TNF-α knockout (KO) mice and anti-TNFR1 antibodies were used to treat EAN. Particularly, the effects of TNF-α deficiency and TNFR1 blockade on macrophage functions were investigated. The onset of EAN in TNF-α KO mice was markedly later than that in wild type (WT) mice. From day 14 post immunization, the clinical signs of TNF-α KO mice were significantly milder than those of their WT counterparts. Further, we showed that the clinical severity of WT mice treated with anti-TNFR1 antibodies was less severe than that of the control WT mice receiving PBS. Nevertheless, no difference with regard to the clinical signs of EAN or inflammatory infiltration in cauda equina was seen between TNF-α KO and WT mice with EAN after blockade of TNFR1. Although TNF-α deficiency did not alter the proliferation of lymphocytes in response to either antigenic or mitogenic stimuli, it down-regulated the production of interleukin (IL)-12 and nitric oxide (NO), and enhanced the production of IL-10 in macrophages. Increased ratio of regulatory T cells (Tregs) and reduced production of interferon (IFN)-γ in cauda equina infiltrating cells, and elevated levels of IgG2b antibodies against P0 peptide 180–199 in sera were found in TNF-α KO mice with EAN. In conclusion, TNF-α deficiency attenuates EAN via altering the M1/M2 balance of macrophages. PMID:22666471

Therapeutic blockade of LIGHT interaction with HVEM and LTβR attenuates in vivo cytotoxic allogeneic responses

PubMed Central

del Rio, Maria-Luisa; Fernandez-Renedo, Carlos; Scheu, Stefanie; Pfeffer, Klaus; Shintani, Yasushi; Kronenberg, Mitchell; Chaloin, Olivier; Schneider, Pascal; Rodriguez-Barbosa, Jose-Ignacio

2016-01-01

Background TNF/TNFR superfamily members conform a group of molecular interaction pathways of essential relevance during the process of T cell activation and differentiation towards effector cells and particularly for the maintenance phase of the immune response. Specific blockade of these interacting pathways, such as CD40/CD40L, contributes to modulate the deleterious outcome of allogeneic immune responses. We postulated that antagonizing the interaction of LIGHT expression on activated T cells with its receptors, HVEM and LTβR may decrease T cell-mediated allogeneic responses. Methods A flow cytometry competition assay was designed to identify anti-LIGHT monoclonal antibodies capable to prevent the interaction of mouse LIGHT with its receptors expressed on transfected cells. An antibody with the desired specificity was evaluated in a short-term in vivo allogeneic cytotoxic assay and tested for its ability to detect endogenous mouse LIGHT. Results We provide evidence for the first time that in mice, as previously described in humans, LIGHT protein is rapidly and transiently expressed after T cell activation, and this expression was stronger on CD8 T cells than on CD4 T cells. Two anti-LIGHT antibodies prevented interactions of mouse LIGHT with its two known receptors HVEM and LTβR. In vivo administration of anti-LIGHT antibody (clone 10F12) ameliorated host anti-donor short-term cytotoxic response in WT B6 mice, although to a lesser extent than that observed in LIGHT-deficient mice. Conclusions The therapeutic targeting of LIGHT may contribute to achieve a better control of cytotoxic responses refractory to current immunosuppressive drugs in transplantation. PMID:25226173

The novel micro-opioid receptor antagonist, [N-allyl-Dmt(1)]endomorphin-2, attenuates the enhancement of GABAergic neurotransmission by ethanol.

PubMed

Li, Qiang; Okada, Yoshio; Marczak, Ewa; Wilson, Wilkie A; Lazarus, Lawrence H; Swartzwelder, H S

2009-01-01

We investigated the effects of [N-allyl-Dmt(1)]endomorphin-2 (TL-319), a novel and highly potent micro-opioid receptor antagonist, on ethanol (EtOH)-induced enhancement of GABA(A) receptor-mediated synaptic activity in the hippocampus. Evoked and spontaneous inhibitory postsynaptic currents (eIPSCs and sIPSCs) were isolated from CA1 pyramidal cells from brain slices of male rats using whole-cell patch-clamp techniques. TL-319 had no effect on the baseline amplitude of eIPSCs or the frequency of sIPSCs. However, it induced a dose-dependent suppression of an ethanol-induced increase of sIPSC frequency with full reversal at concentrations of 500 nM and higher. The non-specific competitive opioid receptor antagonist naltrexone also suppressed EtOH-induced increases in sIPSC frequency but only at a concentration of 60 microM. These data indicate that blockade of micro-opioid receptors by low concentrations of [N-allyl-Dmt(1)]endomorphin-2 can reverse ethanol-induced increases in GABAergic neurotransmission and possibly alter its anxiolytic or sedative effects. This suggests the possibility that high potency opioid antagonists may emerge as possible candidate compounds for the treatment of ethanol addiction.

Angiotensin-converting enzyme inhibition and angiotensin AT1 receptor blockade downregulate angiotensin-converting enzyme expression and attenuate renal injury in streptozotocin-induced diabetic rats.

PubMed

Motawi, Tarek K; El-Maraghy, Shohda A; Senousy, Mahmoud A

2013-07-01

Angiotensin-converting enzyme (ACE) is upregulated in the diabetic kidney and contributes to renal injury. This study investigates the possible beneficial effects of the ACE inhibitor (ACEI), enalapril and the AT1 receptor blocker (ARB), valsartan, on renal ACE expression, renal structure, and function in streptozotocin (STZ)-induced diabetic rats. Male Wistar rats were allocated into four groups: control, STZ-diabetic rats, and STZ-diabetic rats treated with either enalapril (10 mg/kg/day) or valsartan (50 mg/kg/day) for 8 weeks. Enalapril and valsartan reduced renal ACE mRNA and protein expression, Na(+) /K(+) -ATPase activity, oxidative stress, and serum transforming growth factor-β1 levels compared to the diabetic group. Both treatments normalized renal nitrate/nitrite levels and ameliorated the observed histopathological changes. In conclusion, ACE downregulation by ACEI and ARB indicates that angiotensin II upregulates ACE through AT1 receptor. Prevention of diabetes-induced changes in ACE expression and Na(+) /K(+) -ATPase activity could be a new explanation of the renoprotective effects of ACEIs and ARBs. © 2013 Wiley Periodicals, Inc.

Role of lateral septum glucagon-like peptide 1 receptors in food intake.

PubMed

Terrill, Sarah J; Jackson, Christine M; Greene, Hayden E; Lilly, Nicole; Maske, Calyn B; Vallejo, Samantha; Williams, Diana L

2016-07-01

Hindbrain glucagon-like peptide 1 (GLP-1) neurons project to numerous forebrain areas, including the lateral septum (LS). Using a fluorescently labeled GLP-1 receptor (GLP-1R) agonist, Exendin 4 (Ex4), we demonstrated GLP-1 receptor binding throughout the rat LS. We examined the feeding effects of Ex4 and the GLP-1R antagonist Exendin (9-39) (Ex9) at doses subthreshold for effect when delivered to the lateral ventricle. Intra-LS Ex4 suppressed overnight chow and high-fat diet (HFD) intake, and Ex9 increased chow and HFD intake relative to vehicle. During 2-h tests, intra-LS Ex9 significantly increased 0.25 M sucrose and 4% corn oil. Ex4 can cause nausea, but intra-LS administration of Ex4 did not induce pica. Furthermore, intra-LS Ex4 had no effect on anxiety-like behavior in the elevated plus maze. We investigated the role of LS GLP-1R in motivation for food by examining operant responding for sucrose on a progressive ratio (PR) schedule, with and without a nutrient preload to maximize GLP-1 neuron activation. The preload strongly suppressed PR responding, but blockade of GLP-1R in the intermediate subdivision of the LS did not affect motivation for sucrose under either load condition. The ability of the nutrient load to suppress subsequent chow intake was significantly attenuated by intermediate LS Ex9 treatment. By contrast, blockade of GLP-1R in the dorsal subdivision of the LS increased both PR responding and overnight chow intake. Together, these studies suggest that endogenous activity of GLP-1R in the LS influence feeding, and dLS GLP-1Rs, in particular, play a role in motivation. Copyright © 2016 the American Physiological Society.

Role of lateral septum glucagon-like peptide 1 receptors in food intake

PubMed Central

Jackson, Christine M.; Greene, Hayden E.; Lilly, Nicole; Maske, Calyn B.; Vallejo, Samantha

2016-01-01

Hindbrain glucagon-like peptide 1 (GLP-1) neurons project to numerous forebrain areas, including the lateral septum (LS). Using a fluorescently labeled GLP-1 receptor (GLP-1R) agonist, Exendin 4 (Ex4), we demonstrated GLP-1 receptor binding throughout the rat LS. We examined the feeding effects of Ex4 and the GLP-1R antagonist Exendin (9–39) (Ex9) at doses subthreshold for effect when delivered to the lateral ventricle. Intra-LS Ex4 suppressed overnight chow and high-fat diet (HFD) intake, and Ex9 increased chow and HFD intake relative to vehicle. During 2-h tests, intra-LS Ex9 significantly increased 0.25 M sucrose and 4% corn oil. Ex4 can cause nausea, but intra-LS administration of Ex4 did not induce pica. Furthermore, intra-LS Ex4 had no effect on anxiety-like behavior in the elevated plus maze. We investigated the role of LS GLP-1R in motivation for food by examining operant responding for sucrose on a progressive ratio (PR) schedule, with and without a nutrient preload to maximize GLP-1 neuron activation. The preload strongly suppressed PR responding, but blockade of GLP-1R in the intermediate subdivision of the LS did not affect motivation for sucrose under either load condition. The ability of the nutrient load to suppress subsequent chow intake was significantly attenuated by intermediate LS Ex9 treatment. By contrast, blockade of GLP-1R in the dorsal subdivision of the LS increased both PR responding and overnight chow intake. Together, these studies suggest that endogenous activity of GLP-1R in the LS influence feeding, and dLS GLP-1Rs, in particular, play a role in motivation. PMID:27194565

The investigation of neonatal MK-801 administration and physical environmental enrichment on emotional and cognitive functions in adult Balb/c mice.

PubMed

Akillioglu, Kubra; Babar Melik, Emine; Melik, Enver; Kocahan, Sayad

2012-09-01

N-methyl-D-aspartate (NMDA) receptors play an important role in brain maturation and developmental processes. It is known that growing up in an enriched environment has effects on emotional and cognitive performance. In our study, we evaluated the effects of physically enriched environment on the emotional and cognitive functions of the adult brain in the setting of previous NMDA receptor hypoactivity during the critical developmental period of the nervous system. In this study, NMDA receptor blockade was induced 5-10 days postnatally (PD5-10) using MK-801 in mice Balb/c (twice a day 0.25 mg/kg, for 5 days, intraperitoneal). MK-801 was given to developing mice living in a standard (SE) and an enrichment environment (EE) and once the animals reached adulthood, emotional behaviors were evaluated using an open field test (OF) and an elevated plus maze (EPM) test whereas cognitive processes were evaluated using the Morris water-maze (MWM). The EE group showed decreased locomotor activity (p<0.05) in the OF and increased exploratory behaviour (p<0.01) and decreased fear of heights/anxiety-like behaviour (p<0.05) in the EPM test. The EE had positive effects on spatial learning in the MWM (p<0.05). Blockade of the NMDA receptor increased the fear of height (p<0.05), decreased exploratory behaviour and locomotor activity (p<0.001). Also, it led to decreased spatial learning (p<0.05). The decreases in spatial learning and exploratory behaviours and the increase in fear of heights/anxiety-like behaviour with NMDA receptor blockade was not reversed by EE. NMDA receptor blockade during the critical period of development led to deterioration in the emotional and cognitive processes during adulthood. An enriched environmental did not reverse the deleterious effects of the NMDA receptor blockade on emotional and cognitive functions. Copyright © 2012. Published by Elsevier Inc.

The Novel μ-Opioid Receptor Antagonist, [N-Allyl-Dmt1]Endomorphin-2, Attenuates the Enhancement of GABAergic Neurotransmission by Ethanol

PubMed Central

Li, Qiang; Okada, Yoshio; Marczak, Ewa; Wilson, Wilkie A.; Lazarus, Lawrence H.; Swartzwelder, H. S.

2009-01-01

Aims: We investigated the effects of [N-allyl-Dmt1]endomorphin-2 (TL-319), a novel and highly potent μ-opioid receptor antagonist, on ethanol (EtOH)-induced enhancement of GABAA receptor-mediated synaptic activity in the hippocampus. Methods: Evoked and spontaneous inhibitory postsynaptic currents (eIPSCs and sIPSCs) were isolated from CA1 pyramidal cells from brain slices of male rats using whole-cell patch-clamp techniques. Results: TL-319 had no effect on the baseline amplitude of eIPSCs or the frequency of sIPSCs. However, it induced a dose-dependent suppression of an ethanol-induced increase of sIPSC frequency with full reversal at concentrations of 500 nM and higher. The non-specific competitive opioid receptor antagonist naltrexone also suppressed EtOH-induced increases in sIPSC frequency but only at a concentration of 60 μM. Conclusion: These data indicate that blockade of μ-opioid receptors by low concentrations of [N-allyl-Dmt1]endomorphin-2 can reverse ethanol-induced increases in GABAergic neurotransmission and possibly alter its anxiolytic or sedative effects. This suggests the possibility that high potency opioid antagonists may emerge as possible candidate compounds for the treatment of ethanol addiction. PMID:18971291

Antihyperglycemic action of rhodiola-aqeous extract in type1-like diabetic rats

PubMed Central

2014-01-01

Background Rhodiola rosea (Rhodiola) is a plant in the Crassulaceae family that grows in cold regions of the world. It is mainly used in clinics as an adaptogen. Recently, it has been mentioned that Rhodiola increases plasma β-endorphin to lower blood pressure. Thus, the present study aims to investigate the antidiabetic action of Rhodiola in relation to opioids in streptozotocin-induced diabetic rats (STZ-diabetic rats). Methods In the present study, the plasma glucose was analyzed with glucose oxidase method, and the determination of plasma β-endorphin was carried out using a commercially available enzyme-linked immunosorbent assay. The adrenalectomy of STZ-diabetic rats was used to evaluate the role of β-endorphin. In addition, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blotting analysis were performed to investigate mRNA and protein expressions. Results Rhodiola-water extract dose-dependently lowered the plasma glucose in STZ-diabetic rats and this action was reversed by blockade of opioid μ-receptors using cyprodime. An increase of plasma β-endorphin by rhodiola-water extract was also observed in same manner. The plasma glucose lowering action of rhodiola-water extract was attenuated in bilateral adrenalectomized rats. In addition, continuous administration of rhodiola-water extract for 3 days in STZ-diabetic rats resulted in an increased expression of glucose transporter subtype 4 (GLUT 4) in skeletal muscle and a marked reduction of phosphoenolpyruvate carboxykinase (PEPCK) expression in liver. These effects were also reversed by blockade of opioid μ-receptors. Conclusions Taken together, rhodiola-water extract improves hyperglycemia via an increase of β-endorphin secretion from adrenal gland to activate opioid μ-receptors in STZ-diabetic rats. PMID:24417880

Consequence of dopamine D2 receptor blockade on the hyperphagic effect induced by cannabinoid CB1 and CB2 receptors in layers.

PubMed

Khodadadi, M; Zendehdel, M; Baghbanzadeh, A; Babapour, V

2017-10-01

1. Endocannabinoids (ECBs) and their receptors play a regulatory function on several physiological processes such as feed-intake behaviour, mainly in the brain. This study was carried out in order to investigate the effects of the dopaminergic D1 and D2 receptors on CB1/CB2 ECB receptor-induced hyperphagia in 3-h feed-deprived neonatal layer chickens. 2. A total of 8 experiments were designed to explore the interplay of these two modulatory systems on feed intake in neonatal chickens. In Experiment 1, chickens were intracerebroventricular (ICV) injected with control solution, l-DOPA (levo-dihydroxyphenylalanine as precursor of dopamine; 125 nmol), 2-AG (2-arachidonoylglycerol as CB 1 receptor agonist; 2 µg) and co-administration of l-DOPA (125 nmol) plus 2-AG (2 µg). Experiments 2-4 were similar to Experiment 1 except birds were injected with either 6-OHDA (6-hydroxydopamine as dopamine synthesis inhibitor; 150 nmol), SCH23390 (D1 receptor antagonist; 5 nmol) and AMI-193 (D2 receptor antagonist; 5 nmol) instead of l-DOPA, respectively. Additionally, Experiments 5-8 followed the previous ones using the same dose of l-DOPA, 6-OHDA and dopamine antagonists except that birds were injected with CB65 (CB2 receptor agonist; 5 µg) instead of 2-AG. Coadministrations were at the same dose for each experiment. Cumulative feed intakes were measured until 120 min after each injection. 3. ICV administration of 6-OHDA and AMI-193 significantly attenuated 2-AG-induced hyperphagia. Interestingly, the hyperphagic effect of CB65 was significantly attenuated by administration of l-DOPA, whereas the administration of 6-OHDA and AMI-193 together amplified the hyperphagic effect of CB65. 4. It was concluded that cannabinoid-induced feeding behaviour is probably modulated by dopamine receptors in neonatal layer-type chickens. It seems that their interaction may be mediated by the D2-dopamine receptor.

Endothelin-A receptor blockade slows the progression of renal injury in experimental renovascular disease.

PubMed

Kelsen, Silvia; Hall, John E; Chade, Alejandro R

2011-07-01

Endothelin (ET)-1, a potent renal vasoconstrictor with mitogenic properties, is upregulated by ischemia and has been shown to induce renal injury via the ET-A receptor. The potential role of ET-A blockade in chronic renovascular disease (RVD) has not, to our knowledge, been previously reported. We hypothesized that chronic ET-A receptor blockade would preserve renal hemodynamics and slow the progression of injury of the stenotic kidney in experimental RVD. Renal artery stenosis, a major cause of chronic RVD, was induced in 14 pigs and observed for 6 wk. In half of the pigs, chronic ET-A blockade was initiated (RVD+ET-A, 0.75 mg·kg(-1)·day(-1)) at the onset of RVD. Single-kidney renal blood flow, glomerular filtration rate, and perfusion were quantified in vivo after 6 wk using multidetector computer tomography. Renal microvascular density was quantified ex vivo using three-dimensional microcomputer tomography, and growth factors, inflammation, apoptosis, and fibrosis were determined in renal tissue. The degree of stenosis and increase in blood pressure were similar in RVD and RVD+ET-A pigs. Renal hemodynamics, function, and microvascular density were decreased in the stenotic kidney but preserved by ET-A blockade, accompanied by increased renal expression of vascular endothelial growth factor, hepatocyte growth factor, and downstream mediators such as phosphorilated-Akt, angiopoietins, and endothelial nitric oxide synthase. ET-A blockade also reduced renal apoptosis, inflammation, and glomerulosclerosis. This study shows that ET-A blockade slows the progression of renal injury in experimental RVD and preserves renal hemodynamics, function, and microvascular density in the stenotic kidney. These results support a role for ET-1/ET-A as a potential therapeutic target in chronic RVD.

Endothelin-A receptor blockade slows the progression of renal injury in experimental renovascular disease

PubMed Central

Kelsen, Silvia; Hall, John E.

2011-01-01

Endothelin (ET)-1, a potent renal vasoconstrictor with mitogenic properties, is upregulated by ischemia and has been shown to induce renal injury via the ET-A receptor. The potential role of ET-A blockade in chronic renovascular disease (RVD) has not, to our knowledge, been previously reported. We hypothesized that chronic ET-A receptor blockade would preserve renal hemodynamics and slow the progression of injury of the stenotic kidney in experimental RVD. Renal artery stenosis, a major cause of chronic RVD, was induced in 14 pigs and observed for 6 wk. In half of the pigs, chronic ET-A blockade was initiated (RVD+ET-A, 0.75 mg·kg−1·day−1) at the onset of RVD. Single-kidney renal blood flow, glomerular filtration rate, and perfusion were quantified in vivo after 6 wk using multidetector computer tomography. Renal microvascular density was quantified ex vivo using three-dimensional microcomputer tomography, and growth factors, inflammation, apoptosis, and fibrosis were determined in renal tissue. The degree of stenosis and increase in blood pressure were similar in RVD and RVD+ET-A pigs. Renal hemodynamics, function, and microvascular density were decreased in the stenotic kidney but preserved by ET-A blockade, accompanied by increased renal expression of vascular endothelial growth factor, hepatocyte growth factor, and downstream mediators such as phosphorilated-Akt, angiopoietins, and endothelial nitric oxide synthase. ET-A blockade also reduced renal apoptosis, inflammation, and glomerulosclerosis. This study shows that ET-A blockade slows the progression of renal injury in experimental RVD and preserves renal hemodynamics, function, and microvascular density in the stenotic kidney. These results support a role for ET-1/ET-A as a potential therapeutic target in chronic RVD. PMID:21478482

G-protein-coupled receptors signaling pathways in new antiplatelet drug development.

PubMed

Gurbel, Paul A; Kuliopulos, Athan; Tantry, Udaya S

2015-03-01

Platelet G-protein-coupled receptors influence platelet function by mediating the response to various agonists, including ADP, thromboxane A2, and thrombin. Blockade of the ADP receptor, P2Y12, in combination with cyclooxygenase-1 inhibition by aspirin has been among the most widely used pharmacological strategies to reduce cardiovascular event occurrence in high-risk patients. The latter dual pathway blockade strategy is one of the greatest advances in the field of cardiovascular medicine. In addition to P2Y12, the platelet thrombin receptor, protease activated receptor-1, has also been recently targeted for inhibition. Blockade of protease activated receptor-1 has been associated with reduced thrombotic event occurrence when added to a strategy using P2Y12 and cyclooxygenase-1 inhibition. At this time, the relative contributions of these G-protein-coupled receptor signaling pathways to in vivo thrombosis remain incompletely defined. The observation of treatment failure in ≈10% of high-risk patients treated with aspirin and potent P2Y12 inhibitors provides the rationale for targeting novel pathways mediating platelet function. Targeting intracellular signaling downstream from G-protein-coupled receptor receptors with phosphotidylionisitol 3-kinase and Gq inhibitors are among the novel strategies under investigation to prevent arterial ischemic event occurrence. Greater understanding of the mechanisms of G-protein-coupled receptor-mediated signaling may allow the tailoring of antiplatelet therapy. © 2015 American Heart Association, Inc.

Immune cell-poor melanomas benefit from PD-1 blockade after targeted type I IFN activation.

PubMed

Bald, Tobias; Landsberg, Jennifer; Lopez-Ramos, Dorys; Renn, Marcel; Glodde, Nicole; Jansen, Philipp; Gaffal, Evelyn; Steitz, Julia; Tolba, Rene; Kalinke, Ulrich; Limmer, Andreas; Jönsson, Göran; Hölzel, Michael; Tüting, Thomas

2014-06-01

Infiltration of human melanomas with cytotoxic immune cells correlates with spontaneous type I IFN activation and a favorable prognosis. Therapeutic blockade of immune-inhibitory receptors in patients with preexisting lymphocytic infiltrates prolongs survival, but new complementary strategies are needed to activate cellular antitumor immunity in immune cell-poor melanomas. Here, we show that primary melanomas in Hgf-Cdk4(R24C) mice, which imitate human immune cell-poor melanomas with a poor outcome, escape IFN-induced immune surveillance and editing. Peritumoral injections of immunostimulatory RNA initiated a cytotoxic inflammatory response in the tumor microenvironment and significantly impaired tumor growth. This critically required the coordinated induction of type I IFN responses by dendritic, myeloid, natural killer, and T cells. Importantly, antibody-mediated blockade of the IFN-induced immune-inhibitory interaction between PD-L1 and PD-1 receptors further prolonged the survival. These results highlight important interconnections between type I IFNs and immune-inhibitory receptors in melanoma pathogenesis, which serve as targets for combination immunotherapies. Using a genetically engineered mouse melanoma model, we demonstrate that targeted activation of the type I IFN system with immunostimulatory RNA in combination with blockade of immune-inhibitory receptors is a rational strategy to expose immune cell-poor tumors to cellular immune surveillance. ©2014 American Association for Cancer Research.

Endocannabinoids in Liver Disease

PubMed Central

Tam, Joseph; Liu, Jie; Mukhopadhyay, Bani; Cinar, Resat; Godlewski, Grzegorz; Kunos, George

2010-01-01

Endocannabinoids are lipid mediators of the same cannabinoid (CB) receptors that mediate the effects of marijuana. The endocannabinoid system (ECS) consists of CB receptors, endocannabinoids, and the enzymes involved in their biosynthesis and degradation, and is present both in brain and peripheral tissues, including the liver. The hepatic ECS is activated in various liver diseases, which contributes to the underlying pathologies. In cirrhosis of various etiologies, activation of vascular and cardiac CB1 receptors by macrophage- and platelet-derived endocannabinoids contribute to the vasodilated state and cardiomyopathy, which can be reversed by CB1 blockade. In mouse models of liver fibrosis, activation of CB1 receptors on hepatic stellate cells is fibrogenic, and CB1 blockade slows the progression of fibrosis. Fatty liver induced by high-fat diets or chronic alcohol feeding depend on activation of peripheral, including hepatic CB1 receptors, which also contribute to insulin resistance and dyslipidemias. Although the documented therapeutic potential of CB1 blockade is limited by neuropsychiatric side effects, these may be mitigated by using novel, peripherally restricted CB1 antagonists. PMID:21254182

Promiscuous dimerization of the growth hormone secretagogue receptor (GHS-R1a) attenuates ghrelin-mediated signaling.

PubMed

Schellekens, Harriët; van Oeffelen, Wesley E P A; Dinan, Timothy G; Cryan, John F

2013-01-04

G protein-coupled receptors (GPCRs), such as the ghrelin receptor (GHS-R1a), the melanocortin 3 receptor (MC(3)), and the serotonin 2C receptor (5-HT(2C)), are well known for their key role in the homeostatic control of food intake and energy balance. Ghrelin is the only known gut peptide exerting an orexigenic effect and has thus received much attention as an anti-obesity drug target. In addition, recent data have revealed a critical role for ghrelin in dopaminergic mesolimbic circuits involved in food reward signaling. This study investigates the downstream signaling consequences and ligand-mediated co-internalization following heterodimerization of the GHS-R1a receptor with the dopamine 1 receptor, as well as that of the GHS-R1a-MC(3) heterodimer. In addition, a novel heterodimer between the GHS-R1a receptor and the 5-HT(2C) receptor was identified. Interestingly, dimerization of the GHS-R1a receptor with the unedited 5-HT(2C)-INI receptor, but not with the partially edited 5-HT(2C)-VSV isoform, significantly reduced GHS-R1a agonist-mediated calcium influx, which was completely restored following pharmacological blockade of the 5-HT(2C) receptor. These results combined suggest a potential novel mechanism for fine-tuning GHS-R1a receptor-mediated activity via promiscuous dimerization of the GHS-R1a receptor with other G protein-coupled receptors involved in appetite regulation and food reward. These findings may uncover novel mechanisms of significant relevance for the future pharmacological targeting of the GHS-R1a receptor in the homeostatic regulation of energy balance and in hedonic appetite signaling, both of which play a significant role in the development of obesity.

Celecoxib promotes c-FLIP degradation through Akt-independent inhibition of GSK3.

PubMed

Chen, Shuzhen; Cao, Wei; Yue, Ping; Hao, Chunhai; Khuri, Fadlo R; Sun, Shi-Yong

2011-10-01

Celecoxib is a COX-2 inhibitor that reduces the risk of colon cancer. However, the basis for its cancer chemopreventive activity is not fully understood. In this study, we defined a mechanism of celecoxib action based on degradation of cellular FLICE-inhibitory protein (c-FLIP), a major regulator of the death receptor pathway of apoptosis. c-FLIP protein levels are regulated by ubiquitination and proteasome-mediated degradation. We found that celecoxib controlled c-FLIP ubiquitination through Akt-independent inhibition of glycogen synthase kinase-3 (GSK3), itself a candidate therapeutic target of interest in colon cancer. Celecoxib increased the levels of phosphorylated GSK3, including the α and β forms, even in cell lines, where phosphorylated Akt levels were not increased. Phosphoinositide 3-kinase inhibitors abrogated Akt phosphorylation as expected but had no effect on celecoxib-induced GSK3 phosphorylation. In contrast, protein kinase C (PKC) inhibitors abolished celecoxib-induced GSK3 phosphorylation, implying that celecoxib influenced GSK3 phosphorylation through a mechanism that relied upon PKC and not Akt. GSK3 blockade either by siRNA or kinase inhibitors was sufficient to attenuate c-FLIP levels. Combining celecoxib with GSK3 inhibition enhanced attenuation of c-FLIP and increased apoptosis. Proteasome inhibitor MG132 reversed the effects of GSK3 inhibition and increased c-FLIP ubiquitination, confirming that c-FLIP attenuation was mediated by proteasomal turnover as expected. Our findings reveal a novel mechanism through which the regulatory effects of c-FLIP on death receptor signaling are controlled by GSK3, which celecoxib acts at an upstream level to control independently of Akt.

Celecoxib promotes c-FLIP degradation through Akt-independent inhibition of GSK3

PubMed Central

Chen, Shuzhen; Cao, Wei; Yue, Ping; Hao, Chunhai; Khuri, Fadlo R.; Sun, Shi-Yong

2011-01-01

Celecoxib is a COX2 inhibitor that reduces the risk of colon cancer. However, the basis for its cancer chemopreventive activity is not fully understood. In this study, we defined a mechanism of celecoxib action based on degradation of c-FLIP, a major regulator of the death receptor pathway of apoptosis. c-FLIP protein levels are regulated by ubiquitination and proteasome-mediated degradation. We found that celecoxib controlled c-FLIP ubiquitination through Akt-independent inhibition of GSK3 kinase, itself a candidate therapeutic target of interest in colon cancer. Celecoxib increased the levels of phosphorylated GSK3 (p-GSK3), including the α and β forms, even in cell lines where p-Akt levels were not increased. PI3K inhibitors abrogated Akt phosphorylation as expected but had no effect on celecoxib-induced GSK3 phosphorylation. In contrast, PKC inhibitors abolished celecoxib-induced GSK3 phosphorylation, implying that celecoxib influenced GSK3 phosphorylation through a mechanism relied upon PKC but not Akt. GSK3 blockade either by siRNA or kinase inhibitors was sufficient to attenuate c-FLIP levels. Combining celecoxib with GSK3 inhibition enhanced attenuation of c-FLIP and increased apoptosis. Proteasome inhibitor MG132 reversed the effects of GSK3 inhibition and increased c-FLIP ubiquitination, confirming that c-FLIP attenuation was mediated by proteasomal turnover as expected. Our findings reveal a novel mechanism through which the regulatory effects of c-FLIP on death receptor signaling are controlled by GSK3, which celecoxib acts at an upstream level to control independently of Akt. PMID:21868755

Enhanced motivation for food reward induced by stress and attenuation by corticotrophin-releasing factor receptor antagonism in rats: implications for overeating and obesity

PubMed Central

Liu, Xiu

2014-01-01

Rationale Overeating beyond individuals’ homeostatic needs critically contributes to obesity. The neurobehavioral mechanisms underlying the motivation to consume excessive foods with high calories are not fully understood. Objective The present study examined whether a pharmacological stressor, yohimbine enhances the motivation to procure food reward with an emphasis on comparisons between standard lab chow and high-fat foods. The effects of corticotropin-releasing factor receptor (CRF1) blockade by a CFR1 selective antagonist NBI on the stress-enhanced motivation for food reward were also assessed. Methods Male Sprague-Dawley rats with chow available ad libitum in their home cages were trained to press a lever under a progressive-ratio schedule for deliveries of either standard or high-fat food pellets. For testing yohimbine stress effects, rats received an intraperitoneal administration of yohimbine 10 min before start of the test sessions. For testing effects of CRF1 receptor blockade on stress responses, NBI was administered 20 min prior to yohimbine challenge. Results The rats emitted higher levels of lever responses to procure the high-fat food pellets compared with their counterparts on standard food pellets. Yohimbine challenge facilitated lever responses for the reward in all of the rats, whereas the effect was more robust in the rats on high-fat food pellets compared with their counterparts on standard food pellets. An inhibitory effect of pretreatment with NBI was observed on the enhancing effect of yohimbine challenge but not on the responses under baseline condition without yohimbine administration. Conclusions Stress challenge significantly enhanced the motivation of satiated rats to procure extra food reward, especially the high-fat food pellets. Activation of CRF1 receptors is required for the stress-enhanced motivation for food reward. These results may have implications for our better understanding of the biobehavioral mechanisms of overeating and obesity. PMID:25510859

Enhanced motivation for food reward induced by stress and attenuation by corticotrophin-releasing factor receptor antagonism in rats: implications for overeating and obesity.

PubMed

Liu, Xiu

2015-06-01

Overeating beyond individuals' homeostatic needs critically contributes to obesity. The neurobehavioral mechanisms underlying the motivation to consume excessive foods with high calories are not fully understood. The present study examined whether a pharmacological stressor, yohimbine, enhances the motivation to procure food reward with an emphasis on comparisons between standard lab chow and high-fat foods. The effects of corticotropin-releasing factor (CRF) receptor blockade by a CRF1-selective antagonist NBI on the stress-enhanced motivation for food reward were also assessed. Male Sprague-Dawley rats with chow available ad libitum in their home cages were trained to press a lever under a progressive ratio schedule for deliveries of either standard or high-fat food pellets. For testing yohimbine stress effects, rats received an intraperitoneal administration of yohimbine 10 min before start of the test sessions. For testing effects of CRF1 receptor blockade on stress responses, NBI was administered 20 min prior to yohimbine challenge. The rats emitted higher levels of lever responses to procure the high-fat food pellets compared with their counterparts on standard food pellets. Yohimbine challenge facilitated lever responses for the reward in all of the rats, whereas the effect was more robust in the rats on high-fat food pellets compared with their counterparts on standard food pellets. An inhibitory effect of pretreatment with NBI was observed on the enhancing effect of yohimbine challenge but not on the responses under baseline condition without yohimbine administration. Stress challenge significantly enhanced the motivation of satiated rats to procure extra food reward, especially the high-fat food pellets. Activation of CRF1 receptors is required for the stress-enhanced motivation for food reward. These results may have implications for our better understanding of the biobehavioral mechanisms of overeating and obesity.

Impact of Leukocyte Function-Associated Antigen-1 Blockade on Endogenous Allospecific T Cells to Multiple Minor Histocompatibility Antigen Mismatched Cardiac Allograft.

PubMed

Kwun, Jean; Farris, Alton B; Song, Hyunjin; Mahle, William T; Burlingham, William J; Knechtle, Stuart J

2015-12-01

Blocking leukocyte function-associated antigen (LFA)-1 in organ transplant recipients prolongs allograft survival. However, the precise mechanisms underlying the therapeutic potential of LFA-1 blockade in preventing chronic rejection are not fully elucidated. Cardiac allograft vasculopathy (CAV) is the preeminent cause of late cardiac allograft failure characterized histologically by concentric intimal hyperplasia. Anti-LFA-1 monoclonal antibody was used in a multiple minor antigen-mismatched, BALB.B (H-2B) to C57BL/6 (H-2B), cardiac allograft model. Endogenous donor-specific CD8 T cells were tracked down using major histocompatibility complex multimers against the immunodominant H4, H7, H13, H28, and H60 minor Ags. The LFA-1 blockade prevented acute rejection and preserved palpable beating quality with reduced CD8 T-cell graft infiltration. Interestingly, less CD8 T cell infiltration was secondary to reduction of T-cell expansion rather than less trafficking. The LFA-1 blockade significantly suppressed the clonal expansion of minor histocompatibility antigen-specific CD8 T cells during the expansion and contraction phase. The CAV development was evaluated with morphometric analysis at postoperation day 100. The LFA-1 blockade profoundly attenuated neointimal hyperplasia (61.6 vs 23.8%; P < 0.05), CAV-affected vessel number (55.3 vs 15.9%; P < 0.05), and myocardial fibrosis (grade 3.29 vs 1.8; P < 0.05). Finally, short-term LFA-1 blockade promoted long-term donor-specific regulation, which resulted in attenuated transplant arteriosclerosis. Taken together, LFA-1 blockade inhibits initial endogenous alloreactive T-cell expansion and induces more regulation. Such a mechanism supports a pulse tolerance induction strategy with anti-LFA-1 rather than long-term treatment.

Magnesium attenuates chronic hypersensitivity and spinal cord NMDA receptor phosphorylation in a rat model of diabetic neuropathic pain

PubMed Central

Rondón, L J; Privat, A M; Daulhac, L; Davin, N; Mazur, A; Fialip, J; Eschalier, A; Courteix, C

2010-01-01

Neuropathic pain is a common diabetic complication affecting 8–16% of diabetic patients. It is characterized by aberrant symptoms of spontaneous and stimulus-evoked pain including hyperalgesia and allodynia. Magnesium (Mg) deficiency has been proposed as a factor in the pathogenesis of diabetes-related complications, including neuropathy. In the central nervous system, Mg is also a voltage-dependant blocker of the N-methyl-d-aspartate receptor channels involved in abnormal processing of sensory information. We hypothesized that Mg deficiency might contribute to the development of neuropathic pain and the worsening of clinical and biological signs of diabetes and consequently, that Mg administration could prevent or improve its complications. We examined the effects of oral Mg supplementation (296 mg l−1 in drinking water for 3 weeks) on the development of neuropathic pain and on biological and clinical parameters of diabetes in streptozocin (STZ)-induced diabetic rats. STZ administration induced typical symptoms of type 1 diabetes. The diabetic rats also displayed mechanical hypersensitivity and tactile and thermal allodynia. The level of phosphorylated NMDA receptor NR1 subunit (pNR1) was higher in the spinal dorsal horn of diabetic hyperalgesic/allodynic rats. Magnesium supplementation failed to reduce hyperglycaemia, polyphagia and hypermagnesiuria, or to restore intracellular Mg levels and body growth, but increased insulinaemia and reduced polydipsia. Moreover, it abolished thermal and tactile allodynia, delayed the development of mechanical hypersensitivity, and prevented the increase in spinal cord dorsal horn pNR1. Thus, neuropathic pain symptoms can be attenuated by targeting the Mg-mediated blockade of NMDA receptors, offering new therapeutic opportunities for the management of chronic neuropathic pain. PMID:20837644

Programmed Death-1 Inhibition of Phosphatidylinositol 3-Kinase/AKT/Mechanistic Target of Rapamycin Signaling Impairs Sarcoidosis CD4+ T Cell Proliferation.

PubMed

Celada, Lindsay J; Rotsinger, Joseph E; Young, Anjuli; Shaginurova, Guzel; Shelton, Debresha; Hawkins, Charlene; Drake, Wonder P

2017-01-01

Patients with progressive sarcoidosis exhibit increased expression of programmed death-1 (PD-1) receptor on their CD4 + T cells. Up-regulation of this marker of T cell exhaustion is associated with a reduction in the proliferative response to T cell receptor (TCR) stimulation, a defect that is reversed by PD-1 pathway blockade. Genome-wide association studies and microarray analyses have correlated signaling downstream from the TCR with sarcoidosis disease severity, but the mechanism is not yet known. Reduced phosphatidylinositol 3-kinase (PI3K)/AKT expression inhibits proliferation by inhibiting cell cycle progression. To test the hypothesis that PD-1 expression attenuates TCR-dependent activation of PI3K/AKT activity in progressive systemic sarcoidosis, we analyzed PI3K/AKT/mechanistic target of rapamycin (mTOR) expression at baseline and after PD-1 pathway blockade in CD4 + T cells isolated from patients with sarcoidosis and healthy control subjects. We confirmed an increased percentage of PD-1 + CD4 + T cells and reduced proliferative capacity in patients with sarcoidosis compared with healthy control subjects (P < 0.001). There was a negative correlation with PD-1 expression and proliferative capacity (r = -0.70, P < 0.001). Expression of key mediators of cell cycle progression, including PI3K and AKT, were significantly decreased. Gene and protein expression levels reverted to healthy control levels after PD-1 pathway blockade. Reduction in sarcoidosis CD4 + T cell proliferative capacity is secondary to altered expression of key mediators of cell cycle progression, including the PI3K/AKT/mTOR pathway, via PD-1 up-regulation. This supports the concept that PD-1 up-regulation drives the immunologic deficits associated with sarcoidosis severity by inducing signaling aberrancies in key mediators of cell cycle progression.

Programmed Death-1 Inhibition of Phosphatidylinositol 3-Kinase/AKT/Mechanistic Target of Rapamycin Signaling Impairs Sarcoidosis CD4+ T Cell Proliferation

PubMed Central

Celada, Lindsay J.; Rotsinger, Joseph E.; Young, Anjuli; Shaginurova, Guzel; Shelton, Debresha; Hawkins, Charlene

2017-01-01

Patients with progressive sarcoidosis exhibit increased expression of programmed death-1 (PD-1) receptor on their CD4+ T cells. Up-regulation of this marker of T cell exhaustion is associated with a reduction in the proliferative response to T cell receptor (TCR) stimulation, a defect that is reversed by PD-1 pathway blockade. Genome-wide association studies and microarray analyses have correlated signaling downstream from the TCR with sarcoidosis disease severity, but the mechanism is not yet known. Reduced phosphatidylinositol 3-kinase (PI3K)/AKT expression inhibits proliferation by inhibiting cell cycle progression. To test the hypothesis that PD-1 expression attenuates TCR-dependent activation of PI3K/AKT activity in progressive systemic sarcoidosis, we analyzed PI3K/AKT/mechanistic target of rapamycin (mTOR) expression at baseline and after PD-1 pathway blockade in CD4+ T cells isolated from patients with sarcoidosis and healthy control subjects. We confirmed an increased percentage of PD-1+ CD4+ T cells and reduced proliferative capacity in patients with sarcoidosis compared with healthy control subjects (P < 0.001). There was a negative correlation with PD-1 expression and proliferative capacity (r = −0.70, P < 0.001). Expression of key mediators of cell cycle progression, including PI3K and AKT, were significantly decreased. Gene and protein expression levels reverted to healthy control levels after PD-1 pathway blockade. Reduction in sarcoidosis CD4+ T cell proliferative capacity is secondary to altered expression of key mediators of cell cycle progression, including the PI3K/AKT/mTOR pathway, via PD-1 up-regulation. This supports the concept that PD-1 up-regulation drives the immunologic deficits associated with sarcoidosis severity by inducing signaling aberrancies in key mediators of cell cycle progression. PMID:27564547

Integrated molecular analysis of tumor biopsies on sequential CTLA-4 and PD-1 blockade reveals markers of response and resistance

PubMed Central

Roh, Whijae; Chen, Pei-Ling; Reuben, Alexandre; Spencer, Christine N.; Prieto, Peter A.; Miller, John P.; Gopalakrishnan, Vancheswaran; Wang, Feng; Cooper, Zachary A.; Reddy, Sangeetha M.; Gumbs, Curtis; Little, Latasha; Chang, Qing; Chen, Wei-Shen; Wani, Khalida; Petaccia De Macedo, Mariana; Chen, Eveline; Austin-Breneman, Jacob L.; Jiang, Hong; Roszik, Jason; Tetzlaff, Michael T.; Davies, Michael A.; Gershenwald, Jeffrey E.; Tawbi, Hussein; Lazar, Alexander J.; Hwu, Patrick; Hwu, Wen-Jen; Diab, Adi; Glitza, Isabella C.; Patel, Sapna P.; Woodman, Scott E.; Amaria, Rodabe N.; Prieto, Victor G.; Hu, Jianhua; Sharma, Padmanee; Allison, James P.; Chin, Lynda; Zhang, Jianhua; Wargo, Jennifer A.; Futreal, P. Andrew

2018-01-01

Immune checkpoint blockade produces clinical benefit in many patients. However better biomarkers of response are still needed, and mechanisms of resistance remain incompletely understood. To address this, we recently studied a cohort of melanoma patients treated with sequential checkpoint blockade against cytotoxic T lymphocyte antigen-4 (CTLA-4) followed by programmed death receptor-1 (PD-1), and identified immune markers of response and resistance. Building on these studies, we performed deep molecular profiling including T-cell receptor sequencing (TCR-seq) and whole exome sequencing (WES) within the same cohort, and demonstrated that a more clonal T cell repertoire was predictive of response to PD-1 but not CTLA-4 blockade. Analysis of copy number alterations identified a higher burden of copy number loss in non-responders to CTLA-4 and PD-1 blockade and found that it was associated with decreased expression of genes in immune-related pathways. The effect of mutational load and burden of copy number loss on response was non-redundant, suggesting the potential utility of a combinatorial biomarker to optimize patient care with checkpoint blockade therapy. PMID:28251903

Proximal Tubular Cannabinoid-1 Receptor Regulates Obesity-Induced CKD.

PubMed

Udi, Shiran; Hinden, Liad; Earley, Brian; Drori, Adi; Reuveni, Noa; Hadar, Rivka; Cinar, Resat; Nemirovski, Alina; Tam, Joseph

2017-12-01

Obesity-related structural and functional changes in the kidney develop early in the course of obesity and occur independently of hypertension, diabetes, and dyslipidemia. Activating the renal cannabinoid-1 receptor (CB 1 R) induces nephropathy, whereas CB 1 R blockade improves kidney function. Whether these effects are mediated via a specific cell type within the kidney remains unknown. Here, we show that specific deletion of CB 1 R in the renal proximal tubule cells did not protect the mice from obesity, but markedly attenuated the obesity-induced lipid accumulation in the kidney and renal dysfunction, injury, inflammation, and fibrosis. These effects associated with increased activation of liver kinase B1 and the energy sensor AMP-activated protein kinase, as well as enhanced fatty acid β -oxidation. Collectively, these findings indicate that renal proximal tubule cell CB 1 R contributes to the pathogenesis of obesity-induced renal lipotoxicity and nephropathy by regulating the liver kinase B1/AMP-activated protein kinase signaling pathway. Copyright © 2017 by the American Society of Nephrology.

Intra-Articular Blockade of P2X7 Receptor Reduces the Articular Hyperalgesia and Inflammation in the Knee Joint Synovitis Especially in Female Rats.

PubMed

Teixeira, Juliana Maia; Dias, Elayne Vieira; Parada, Carlos Amílcar; Tambeli, Cláudia Herrera

2017-02-01

Synovitis is a key factor in joint disease pathophysiology, which affects a greater proportion of women than men. P2X7 receptor activation contributes to arthritis, but whether it plays a role in articular inflammatory pain in a sex-dependent manner is unknown. We investigated whether the P2X7 receptor blockade in the knee joint of male and female rats reduces the articular hyperalgesia and inflammation induced by a carrageenan knee joint synovitis model. Articular hyperalgesia was quantified using the rat knee joint incapacitation test and the knee joint inflammation, characterized by the concentration of cytokines tumor necrosis factor-α, interleukin-1β, interleukin-6, and cytokine-induced neutrophil chemoattractant-1, and by neutrophil migration, was quantified using enzyme-linked immunosorbent assay and by myeloperoxidase enzyme activity measurement, respectively. P2X7 receptor blockade by the articular coadministration of selective P2X7 receptor antagonist A740003 with carrageenan significantly reduced articular hyperalgesia, pro-inflammatory cytokine concentrations, and myeloperoxidase activity induced by carrageenan injection into the knee joint of male and estrus female rats. However, a lower dose of P2X7 receptor antagonist was sufficient to significantly induce the antihyperalgesic and anti-inflammatory effects in estrus female but not in male rats. These results suggest that P2X7 receptor activation by endogenous adenosine 5'-triphosphate is essential to articular hyperalgesia and inflammation development in the knee joint of male and female rats. However, female rats are more responsive than male rats to the antihyperalgesic and anti-inflammatory effects induced by P2X7 receptor blockade. P2X7 receptors could be promising therapeutic targets in the treatment of knee joint disease symptoms, especially in women, who are more affected than men by these conditions. Copyright © 2016 American Pain Society. Published by Elsevier Inc. All rights reserved.

Randomized controlled trial using bosentan to enhance the impact of exercise training in subjects with type 2 diabetes mellitus.

PubMed

Schreuder, Tim H A; Duncker, Dirk J; Hopman, Maria T E; Thijssen, Dick H J

2014-11-01

In type 2 diabetes patients, endothelin (ET) receptor blockade may enhance blood flow responses to exercise training. The combination of exercise training and ET receptor blockade may represent a more potent stimulus than training alone to improve vascular function, physical fitness and glucose homeostasis. We assessed the effect of an 8 week exercise training programme combined with either ET blockade or placebo on vasculature, fitness and glucose homeostasis in people with type 2 diabetes. In a double-blind randomized controlled trial, brachial endothelium-dependent and ‑independent dilatation (using flow-mediated dilatation and glyceryl trinitrate, respectively), glucose homeostasis (using Homeostasis Model Assessment for Insulin Resistance (HOMA-IR)) and physical fitness (maximal cycling test) were assessed in 18 men with type 2 diabetes (60 ± 6 years old). Subjects underwent an 8 week exercise training programme, with half of the subjects receiving ET receptor blockade (bosentan) and the other half a placebo, followed by reassessment of the tests above. Exercise training improved physical fitness to a similar extent in both groups, but we did not detect changes in vascular function in either group. This study suggests that there is no adaptation in brachial and femoral artery endothelial function after 8 weeks of training in type 2 diabetes patients. Endothelin receptor blockade combined with exercise training does not additionally alter conduit artery endothelial function or physical fitness in type 2 diabetes. © 2014 The Authors. Experimental Physiology © 2014 The Physiological Society.

Spinal sigma-1 receptor activation increases the production of D-serine in astrocytes which contributes to the development of mechanical allodynia in a mouse model of neuropathic pain.

PubMed

Moon, Ji-Young; Choi, Sheu-Ran; Roh, Dae-Hyun; Yoon, Seo-Yeon; Kwon, Soon-Gu; Choi, Hoon-Seong; Kang, Suk-Yun; Han, Ho-Jae; Kim, Hyun-Woo; Beitz, Alvin J; Oh, Seog-Bae; Lee, Jang-Hern

2015-10-01

We have previously demonstrated that activation of the spinal sigma-1 receptor (Sig-1R) plays an important role in the development of mechanical allodynia (MA) via secondary activation of the N-methyl-d-aspartate (NMDA) receptor. Sig-1Rs have been shown to localize to astrocytes, and blockade of Sig-1Rs inhibits the pathologic activation of astrocytes in neuropathic mice. However, the mechanism by which Sig-1R activation in astrocytes modulates NMDA receptors in neurons is currently unknown. d-serine, synthesized from l-serine by serine racemase (Srr) in astrocytes, is an endogenous co-agonist for the NMDA receptor glycine site and can control NMDA receptor activity. Here, we investigated the role of d-serine in the development of MA induced by spinal Sig-1R activation in chronic constriction injury (CCI) mice. The production of d-serine and Srr expression were both significantly increased in the spinal cord dorsal horn post-CCI surgery. Srr and d-serine were only localized to astrocytes in the superficial dorsal horn, while d-serine was also localized to neurons in the deep dorsal horn. Moreover, we found that Srr exists in astrocytes that express Sig-1Rs. The CCI-induced increase in the levels of d-serine and Srr was attenuated by sustained intrathecal treatment with the Sig-1R antagonist, BD-1047 during the induction phase of neuropathic pain. In behavioral experiments, degradation of endogenous d-serine with DAAO, or selective blockade of Srr by LSOS, effectively reduced the development of MA, but not thermal hyperalgesia in CCI mice. Finally, BD-1047 administration inhibited the development of MA and this inhibition was reversed by intrathecal treatment with exogenous d-serine. These findings demonstrate for the first time that the activation of Sig-1Rs increases the expression of Srr and d-serine in astrocytes. The increased production of d-serine induced by CCI ultimately affects dorsal horn neurons that are involved in the development of MA in neuropathic mice. Copyright © 2015 Elsevier Ltd. All rights reserved.

Intra-accumbal CB1 receptor blockade reduced extinction and reinstatement of morphine.

PubMed

Khaleghzadeh-Ahangar, Hossein; Haghparast, Abbas

2015-10-01

The limbic dopaminergic reward system is the main target of morphine-like drugs which begins from the ventral tegmental area (VTA) and sends its dopaminergic projections to the nucleus accumbens (NAc), amygdala, hippocampus and prefrontal cortex. Cannabinoid receptors exist in afferent neurons from these areas to the NAc and can modulate glutamate synaptic transmission in the NAc. Cannabinoids can interact with the opiate system in reward-related behaviors; nevertheless these systems' interaction in extinction duration and reinstatement has not been shown. In the present study, the effects of bilateral intra-accumbal administration of AM251, a CB1 receptor antagonist, on the duration of the extinction phase and reinstatement to morphine were investigated by conditioned place preference (CPP) paradigm. Forty eight adult male albino Wistar rats were used. Bilateral intra-accumbal administration of AM251 (15, 45 and 90μM/0.5μl DMSO per side) was performed. Subcutaneous administration of morphine (5mg/kg) in three consecutive days was used to induce CPP. The results showed that administration of the maximal dose of AM251 during the extinction period significantly reduces duration of extinction and reinstatement to morphine. Administration of the middle dose during the extinction period significantly attenuated reinstatement to morphine. A single microinjection of the middle dose just before the reinstatement phase significantly attenuated reinstatement to morphine only, while bilateral intra-accumbal administration of neither the lowest dose nor the vehicle (DMSO) had any effects. These results for the first time indicated that CB1 receptors within the NAc are involved in the maintenance of morphine rewarding properties, and morphine seeking behaviors in extinguished morphine-induced CPP rats. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of dopamine D1 receptor blockade on the ERG b- and d-waves during blockade of ionotropic GABA receptors.

PubMed

Popova, Elka; Kostov, Momchil; Kupenova, Petia

2016-01-01

Some data indicate that the dopaminergic and GABAergic systems interact in the vertebrate retina, but the type of interactions is not well understood. In this study we investigated the effect of dopamine D 1 receptor blockade by 75 μM SCH 23390 on the electroretinographic ON (b-wave) and OFF (d-wave) responses in intact frog eyecup preparations and in eyecups where the ionotropic GABA receptors were blocked by 50 μM picrotoxin. Student's t -test, One-way repeated measures ANOVA with Bonferroni post-hoc test and Two-way ANOVA were used for statistical evaluation of the data. We found that SCH 23390 alone significantly enhanced the amplitude of the b- and d-waves without altering their latency. The effect developed rapidly and was fully expressed within 8-11 min after the blocker application. Picrotoxin alone also markedly enhanced the amplitude of the ERG ON and OFF responses and increased their latency significantly. The effect was fully expressed within 25-27 min after picrotoxin application and remained very stable in the next 20 min. The effects of SCH 23390 and picrotoxin are similar to that reported in our previous studies. When SCH 23390 was applied on the background of the fully developed picrotoxin effect, it diminished the amplitude of the b- and d-waves in comparison to the corresponding values obtained during application of picrotoxin alone. Our results demonstrate that the enhancing effect of D 1 receptor blockade on the amplitude of the ERG b- and d-waves is not evident during the ionotropic GABA receptor blockade, indicating an interaction between these neurotransmitter systems in the frog retina. We propose that the inhibitory effect of endogenous dopamine mediated by D 1 receptors on the ERG ON and OFF responses in the frog retina may be due to the dopamine-evoked GABA release.

NMDA Receptors Regulate Genes Responsible for Major Immune Functions of Mononuclears in Human Peripheral Blood.

PubMed

Kuzmina, U Sh; Zainullina, L F; Sadovnikov, S V; Vakhitov, V A; Vakhitova, Yu V

2018-06-19

To determine the role of NMDA receptors in the functional regulation of immunocompetent cells, comparative assay was carried out for genes expressed in the mononuclears in peripheral blood of healthy persons under normal conditions and after blockade of these receptors. The genes, whose expression changed in response to blockade of NMDA receptors in mononuclears, encode the products involved in regulation of the major functions of immune cells, such as proliferation (IL4, VCAM1, and CDKN2A), apoptosis (BAX, MYC, CDKN2A, HSPB1, and CADD45A), activation (IL4R, IL4, VCAM1, and CDKN2A), and differentiation (IL4, VCAM1, and BAX).

[Significance of CRF and dopamine receptors in amygdala for reinforcing effects of opiates and opioids on self-stimulation of lateral hypothalamus in rats].

PubMed

Shabanov, P D; Lebedev, A A; Liubimov, A V; Kornilov, V A

2011-01-01

Bipolar electrodes were implanted in the lateral hypothalamus in a group of 44 Wistar male rats in order to study self-stimulation reaction in the Skinner box. Simultaneously, microcanules were implanted into the central nucleus of the amygdala to inject the drugs (1 microl per injection). The blockade of corticoliberin (CRF) receptors (astressin, 1 microg) or Na+influx currents (xycaine or lidocain 1 microg) by the intrastructural administration of drugs into the amygdala decreased self-stimulation reaction of the lateral hypothalamus in rats by 29-55%. The inhibition of D1 and D2 dopamine receptors in the amygdala with SCH23390 (1 microg) or sulpiride (1 microg) respectively, also reduced self-stimulation but to a lower degree. On the background of blockade of CRF (astressin) and dopamine (sulpiride) receptors as well as sodium influx ionic currents (lidocain) in the amygdala neurons, psychomotor stimulant amphetamine (1 mg/kg) and barbiturate sodium ethaminal (5 mg/kg) retained their psychoactivating effect on self-stimulation (+30-37%), while fentanyl (0.1 mg/kg) and leu-enkephaline (0.1 mg/kg) did not produce this effect. Fentanyl moderately activated self-stimulation only after the blockade of D1 dopamine receptors with SCH23390. After the blockade of CRF receptors, leu-enkephaline strengthened its depressant effect on self-stimulation reaction (-89%). Therefore, if the modulating action of amygdala on the hypothalamus is eliminated, the enhancing effects of opiates (fentanyl) and opioids (leu-encephaline) are blocked, but the effects of psychomotor stimulant amphetamine and barbiturate sodium ethaminal are retained.

[Myostatin blockade therapy for muscular atrophy].

PubMed

Sunada, Yoshihide

2011-11-01

Myostatin, a member of the muscle-specific transforming growth factor (TGF)-β family, negatively regulates skeletal muscle growth. It inhibits muscle stem cell proliferation and differentiation and attenuates adult muscle fiber protein accretion, resulting in decreased skeletal muscle mass. As such, it has been considered a therapeutic target of muscular dystrophy. Notably, administration of a blocking antibody against myostatin ameliorated the pathophysiology of dystrophin-deficient mdx mice. Although a clinical trial of anti-myostatin antibody MYO-029 failed to achieve a significant outcome in patients with muscular dystrophies, various distinct approaches have been taken to establish anti-myostatin therapy, including myostatin decoy receptor ACE-031, small-molecule inhibitors against the myostatin receptor, and myostatin short intertering RNA with collagen-derived carrier particles. The clinical application of anti-myostatin therapeutics in treatment of patients with muscular dystrophy needs further evaluation for safety and specification of the target disease types among the various muscular dystrophies. In addition, myostatin inhibition could be effective for muscle-wasting conditions other than muscular dystrophy- for instance, steroid-induced myopathy, mitochondrial myopathy, or sarcopenia in elderly patients. Moreover, considerable evidence shows that myostatin regulates energy metabolism and that its inhibition can significantly attenuate the progression of obesity and diabetes. It may also be applicable for the prevention of metabolic syndrome. Thus, safe and potent anti-myostatin therapy will have a wide variety of applications in modern medicine.

Dapper1 attenuates hepatic gluconeogenesis and lipogenesis by activating PI3K/Akt signaling.

PubMed

Kuang, Jian-Ren; Zhang, Zhi-Hui; Leng, Wei-Ling; Lei, Xiao-Tian; Liang, Zi-Wen

2017-05-15

Studies have shown that hepatic insulin resistance, a disorder of glucose and lipid metabolism, plays a vital role in type 2 diabetes (T2D). To clarify the function of Dapper1 in glucose and lipid metabolism in the liver, we investigated the relationships between Dapper1 and adenosine triphosphate (ATP)- and Ca 2+ -mediated activation of PI3K/Akt. We observed a reduction in hepatic Dapper1 in db/db (mice that are homozygous for a spontaneous diabetes mutation) and HFD-induced diabetic mice with T2D. Hepatic overexpression of Dapper1 improved hyperglycemia, insulin resistance, and fatty liver. It also increased Akt (pAkt) signaling and repressed both gluconeogenesis and lipogenesis. Conversely, Ad-shDapper1-induced knockdown of hepatic Dapper1 promoted gluconeogenesis and lipogenesis. Furthermore, Dapper1 activated PI3K p110α/Akt in an insulin-independent manner by inducing ATP production and secretion in vitro. Blockade of P2 ATP receptors, the downstream phospholipase C (PLC), or the inositol triphosphate receptor (IP3R all reduced the Dapper1-induced increase in cytosolic free calcium and Dapper1-mediated PI3K/Akt activation, as did removal of calcium in the medium. In conclusion, Dapper1 attenuates hepatic gluconeogenesis and lipogenesis in T2D. Copyright © 2017 Elsevier B.V. All rights reserved.

Interaction of medullary P2 and glutamate receptors mediates the vasodilation in the hindlimb of rat.

PubMed

Korim, Willian Seiji; Ferreira-Neto, Marcos L; Pedrino, Gustavo R; Pilowsky, Paul M; Cravo, Sergio L

2012-12-01

In the nucleus tractus solitarii (NTS) of rats, blockade of extracellular ATP breakdown to adenosine reduces arterial blood pressure (AP) increases that follow stimulation of the hypothalamic defense area (HDA). The effects of ATP on NTS P2 receptors, during stimulation of the HDA, are still unclear. The aim of this study was to determine whether activation of P2 receptors in the NTS mediates cardiovascular responses to HDA stimulation. Further investigation was taken to establish if changes in hindlimb vascular conductance (HVC) elicited by electrical stimulation of the HDA, or activation of P2 receptors in the NTS, are relayed in the rostral ventrolateral medulla (RVLM); and if those responses depend on glutamate release by ATP acting on presynaptic terminals. In anesthetized and paralyzed rats, electrical stimulation of the HDA increased AP and HVC. Blockade of P2 or glutamate receptors in the NTS, with bilateral microinjections of suramin (10 mM) or kynurenate (50 mM) reduced only the evoked increase in HVC by 75 % or more. Similar results were obtained with the blockade combining both antagonists. Blockade of P2 and glutamate receptors in the RVLM also reduced the increases in HVC to stimulation of the HDA by up to 75 %. Bilateral microinjections of kynurenate in the RVLM abolished changes in AP and HVC to injections of the P2 receptor agonist α,β-methylene ATP (20 mM) into the NTS. The findings suggest that HDA-NTS-RVLM pathways in control of HVC are mediated by activation of P2 and glutamate receptors in the brainstem in alerting-defense reactions.

Role of vagal afferents in the ventilatory response to naloxone during loaded breathing in the rabbit.

PubMed

Delpierre, S; Pugnat, C; Duté, N; Jammes, Y

1995-02-15

It was previously shown that inspiratory resistive loading (IRL) increases the cerebrospinal fluid (CSF) level of beta endorphin in awake goats, and also that the slower ventilation induced by injection of this substance into the CSF of anesthetized dogs is suppressed after vagotomy. In the present study, performed on anesthetized rabbits, we evaluated the part played by vagal afferents in the ventilatory response to IRL after opioid receptor blockade by naloxone. During unloaded breathing, naloxone injection did not modify baseline ventilation. Conversely, naloxone partially reversed IRL-induced hypoventilation through an increase in respiratory rate. This effect was abolished after either vagotomy or cold blockade of large vagal fibers, but it persisted after procaine blockade of thin vagal fibers. These results suggest that pulmonary stretch receptors, which are connected to some large vagal afferent fibers, would play a major role in the ventilatory response to IRL under opioid receptor inhibition.

Modulation of basal and stress-induced amygdaloid substance P release by the potent and selective NK1 receptor antagonist L-822429.

PubMed

Singewald, Nicolas; Chicchi, Gary G; Thurner, Clemens C; Tsao, Kwei-Lan; Spetea, Mariana; Schmidhammer, Helmut; Sreepathi, Hari Kishore; Ferraguti, Francesco; Singewald, Georg M; Ebner, Karl

2008-09-01

It has been shown that anxiety and stress responses are modulated by substance P (SP) released within the amygdala. However, there is an important gap in our knowledge concerning the mechanisms regulating extracellular SP in this brain region. To study a possible self-regulating role of SP, we used a selective neurokinin-1 (NK1) receptor antagonist to investigate whether blockade of NK1 receptors results in altered basal and/or stress-evoked SP release in the medial amygdala (MeA), a critical brain area for a functional involvement of SP transmission in enhanced anxiety responses induced by stressor exposure. In vitro binding and functional receptor assays revealed that L-822429 represents a potent and selective rat NK1 receptor antagonist. Intra-amygdaloid administration of L-822429 via inverse microdialysis enhanced basal, but attenuated swim stress-induced SP release, while the low-affinity enantiomer of L-822429 had no effect. Using light and electron microscopy, synaptic contacts between SP-containing fibres and dendrites expressing NK1 receptors was demonstrated in the medial amygdala. Our findings suggest self-regulatory capacity of SP-mediated neurotransmission that differs in the effect on basal and stress-induced release of SP. Under basal conditions endogenous SP can serve as a signal that tonically inhibits its own release via a NK1 receptor-mediated negative feedback action, while under stress conditions SP release is further facilitated by activation of NK1 receptors, likely leading to high local levels of SP and activation of receptors to which SP binds with lower affinity.

Involvement of endogenous cholecystokinin and somatostatin in gastroprotection induced by intraduodenal fat.

PubMed

Brzozowski, T; Konturek, P C; Konturek, S J; Kwiecién, S; Pajdo, R; Brzozowska, I; Hahn, E G

1998-01-01

Duodenal fat such as oleate is known to influence gut functions by release of cholecystokinin (CCK), but the contribution of CCK endogenously released by duodenal fat or by diversion of pancreatic juice from the duodenum in the mechanism of mucosal integrity and gastroprotection has been little studied. This study was designed to compare the effect of CCK-8 and intraduodenal (i.d.) instillation of sodium oleate, or diversion of the pancreatic biliary secretions that are known to release CCK, on the gastric mucosal lesions induced by topical application of 100% ethanol or acidified aspirin (ASA) in rats with or without the pretreatment with a CCK-A receptor antagonist, loxiglumide, or with L-365,260 to block CCK-B receptors. In addition, the effect of suppression of prostaglandin (PG) biosynthesis by indomethacin (5 mg/kg i.p.), inhibition of nitric oxide (NO)-synthase by L-NAME (5 mg/kg i.v.), or blockade of sensory nerves by capsaicin (125 mg/kg s.c.) on the protective activity of sodium oleate was determined. Sodium oleate (50-200 mM i.d.), or diversion of pancreatic juice from the duodenum for 3 h that produced significant rise in plasma CCK levels, significantly reduced gastric lesions induced by 100% ethanol to an extent similar to that induced by exogenous CCK-8 (5 nmol/kg s.c.). The protective effect of oleate or diversion of pancreatic juice was accompanied by an increase in gastric blood flow (GBF). Both protection and accompanying hyperemia were completely abolished by blockade of CCK-A receptors with loxiglumide, whereas L-365,260, an antagonist of CCK-B receptors, had no effect. Oleate given i.d. significantly attenuated acidified ASA-induced gastric lesions and gastric secretion while increasing the luminal concentration of somatostatin. These effects were significantly reduced by loxiglumide but not by L-365,260. In contrast, CCK-8, which stimulated gastric acid secretion, failed to affect the lesions induced by acidified ASA and the decrease in the GBF produced by this ulcerogen. Indomethacin, which suppressed PG generation by approximately 90%, failed to influence the protective activity of oleate or CCK-8 against ethanol-induced lesions, whereas L-NAME, vagotomy, or sensory denervation significantly attenuated this protection and accompanying hyperemia. Addition to L-NAME of L-arginine, but not D-arginine, restored the protective and hyperemic effects of CCK-8 and duodenal oleate against gastric lesions induced by ethanol or acidified ASA. We conclude that endogenous CCK released by oleate or diversion of pancreatic secretion exerts a potent gastroprotective action on the stomach involving predominantly CCK-A receptors and depending on vagal activity, and hyperemia mediated by NO and sensory nerves but unrelated to acid secretory effects and endogenous PG.

Is age-dependent, ketamine-induced apoptosis in the rat somatosensory cortex influenced by temperature?

PubMed Central

Gutierrez, Silvia; Carnes, Ansley; Finucane, Beth; Oelsner, Gabrielle Musci William; Hicks, Lucretia; Russell, Gregory B.; Liu, Chun; Turner, Christopher P.

2010-01-01

General anesthetics have long been thought to be relatively safe but recent clinical studies have revealed that exposure of very young children (4 years or less) to agents that act by blocking the N-methyl-D-aspartate receptor (NMDAR) can lead to cognitive deficits as they mature. In rodent and non-human primate studies, blockade of this receptor during the perinatal period leads to a number of molecular, cellular and behavioral pathologies. Despite the overwhelming evidence from such studies, doubt remains as to their clinical relevance. A key issue is whether the primary injury (apoptotic cell death) is specific to receptor blockade or due to non-specific, patho-physiological changes. Principal to this argument is that loss of core body temperature following NMDAR blockade could explain why injury is observed hours later. We therefore examined the neurotoxicity of the general anesthetic ketamine in P7, P14 and P21 rats while monitoring core body temperature. We found that, at P7, ketamine induced the pro-apoptotic enzyme activated caspase-3 in a dose-dependent manner. As expected, injury was greatly diminished by P14 and absent by P21. However, contrary to expectations, we found that core body temperature was not a factor in determining injury. Our data imply that injury is directly related to receptor blockade and is unlikely to be overcome by artificially changing core body temperature. PMID:20298758

Hypertension: renin-angiotensin-aldosterone system alterations.

PubMed

Te Riet, Luuk; van Esch, Joep H M; Roks, Anton J M; van den Meiracker, Anton H; Danser, A H Jan

2015-03-13

Blockers of the renin-angiotensin-aldosterone system (RAAS), that is, renin inhibitors, angiotensin (Ang)-converting enzyme (ACE) inhibitors, Ang II type 1 receptor antagonists, and mineralocorticoid receptor antagonists, are a cornerstone in the treatment of hypertension. How exactly they exert their effect, in particular in patients with low circulating RAAS activity, also taking into consideration the so-called Ang II/aldosterone escape that often occurs after initial blockade, is still incompletely understood. Multiple studies have tried to find parameters that predict the response to RAAS blockade, allowing a personalized treatment approach. Consequently, the question should now be answered on what basis (eg, sex, ethnicity, age, salt intake, baseline renin, ACE or aldosterone, and genetic variance) a RAAS blocker can be chosen to treat an individual patient. Are all blockers equal? Does optimal blockade imply maximum RAAS blockade, for example, by combining ≥2 RAAS blockers or by simply increasing the dose of 1 blocker? Exciting recent investigations reveal a range of unanticipated extrarenal effects of aldosterone, as well as a detailed insight in the genetic causes of primary aldosteronism, and mineralocorticoid receptor blockers have now become an important treatment option for resistant hypertension. Finally, apart from the deleterious ACE-Ang II-Ang II type 1 receptor arm, animal studies support the existence of protective aminopeptidase A-Ang III-Ang II type 2 receptor and ACE2-Ang-(1 to 7)-Mas receptor arms, paving the way for multiple new treatment options. This review provides an update about all these aspects, critically discussing the many controversies and allowing the reader to obtain a full understanding of what we currently know about RAAS alterations in hypertension. © 2015 American Heart Association, Inc.

Have we fallen off target with concerns surrounding dual RAAS blockade?

PubMed

Lattanzio, Michael R; Weir, Matthew R

2010-09-01

A misinterpretation of the results from ONTARGET (Ongoing Telmisartan alone and in combination with ramipril Global Endpoint Trial) has sparked both efficacy and safety concerns within the nephrology community regarding the utilization of dual RAAS blockade to achieve more desirable renal outcomes. Two important considerations are requisite prior to interpreting these results, specifically: the context of the cohort studied (non-proteinuric CKD patients at low risk of progression) and the inadequate power of the study to assess renal outcomes. The cardiac and renal protection afforded from dual RAAS blockade in select populations, particularly proteinuric CKD and CHF, is supported by literature. Moreover, the response to dual RAAS blockade involving different combinations of ACE inhibitors, angiotensin receptor blockers, mineralocorticoid receptor antagonists, and direct renin inhibitors, may not be uniform amongst all patient populations. Will we continue to withhold the appropriate medical therapy from certain individuals based on misconstrued data? The proceedings provide a critical analysis of the ONTARGET study and an evidence-based substantiation for the utilization of various forms of dual RAAS blockade in proteinuric kidney disease and beyond.

Hawthorn (Crataegus monogyna Jacq.) extract exhibits atropine-sensitive activity in a cultured cardiomyocyte assay.

PubMed

Salehi, Satin; Long, Shannon R; Proteau, Philip J; Filtz, Theresa M

2009-01-01

Hawthorn (Crataegus spp.) plant extract is used as a herbal alternative medicine for the prevention and treatment of various cardiovascular diseases. Recently, it was shown that hawthorn extract preparations caused negative chronotropic effects in a cultured neonatal murine cardiomyocyte assay, independent of beta-adrenergic receptor blockade. The aim of this study was to further characterize the effect of hawthorn extract to decrease the contraction rate of cultured cardiomyocytes. To test the hypothesis that hawthorn is acting via muscarinic receptors, the effect of hawthorn extract on atrial versus ventricular cardiomyocytes in culture was evaluated. As would be expected for activation of muscarinic receptors, hawthorn extract had a greater effect in atrial cells. Atrial and/or ventricular cardiomyocytes were then treated with hawthorn extract in the presence of atropine or himbacine. Changes in the contraction rate of cultured cardiomyocytes revealed that both muscarinic antagonists significantly attenuated the negative chronotropic activity of hawthorn extract. Using quinuclidinyl benzilate, L-[benzylic-4,4'-(3)H] ([(3)H]-QNB) as a radioligand antagonist, the effect of a partially purified hawthorn extract fraction to inhibit muscarinic receptor binding was quantified. Hawthorn extract fraction 3 dose-dependently inhibited [(3)H]-QNB binding to mouse heart membranes. Taken together, these findings suggest that decreased contraction frequency by hawthorn extracts in neonatal murine cardiomyocytes may be mediated via muscarinic receptor activation.

Hypoxic response in newborn rat is attenuated by neurokinin-1 receptor blockade.

PubMed

Wickström, H Ronny; Berner, Jonas; Holgert, Hans; Hökfelt, Tomas; Lagercrantz, Hugo

2004-04-20

Substance P (SP) is considered to be involved in the regulation of respiration, in particular when respiratory demands are increased, such as during hypoxic stress. In the present study we have investigated the effects of intracerebroventricular pre-treatment with the selective NK-1 receptor antagonist RP67580 on the respiratory response to hypoxia in 5-day-old rat pups. Basal respiration was not altered by RP67580. When subjected to hypoxia (10% O(2)), rat pups pre-treated with RP67580 were unable to sustain the increased respiratory frequency at 10 min. In situ hybridisation demonstrated increased expression of c-fos mRNA in several brainstem areas following hypoxia. This activation was blocked by the antagonist in the retrotrapezoid nucleus and the rostral ventrolateral medulla, areas known to be involved in the hypoxic ventilatory response. This study corroborates a role of endogenously released SP, mediated via NK-1 receptors, in the sustained response to hypoxia in 5-day-old rat pups and suggests that neurons in the rostral ventrolateral medulla are important in this function. It also represents a further example that neuropeptides are released under stressful conditions.

Early RAAS Blockade Exerts Renoprotective Effects in Autosomal Recessive Alport Syndrome.

PubMed

Uchida, Nao; Kumagai, Naonori; Nozu, Kandai; Fu, Xue Jun; Iijima, Kazumoto; Kondo, Yoshiaki; Kure, Shigeo

2016-11-01

Alport syndrome is a progressive renal disease caused by mutations in COL4A3, COL4A4, and COL4A5 genes that encode collagen type IV alpha 3, alpha 4, and alpha 5 chains, respectively. Because of abnormal collagen chain, glomerular basement membrane becomes fragile and most of the patients progress to end-stage renal disease in early adulthood. COL4A5 mutation causes X-linked form of Alport syndrome, and two mutations in either COL4A3 or COL4A4 causes an autosomal recessive Alport syndrome. Recently, renin-angiotensin-aldosterone system (RAAS) blockade has been shown to attenuate effectively disease progression in Alport syndrome. Here we present three Japanese siblings and their father all diagnosed with autosomal recessive Alport syndrome and with different clinical courses, suggesting the importance of the early initiation of RAAS blockade. The father was diagnosed with Alport syndrome. His consanguineous parents and his wife were healthy. All three siblings showed hematuria since infancy. Genetic analysis revealed that they shared the same gene mutations in COL4A3 in a compound heterozygous state: c.2330G>A (p.Gly777Ala) from the mother and c.4354A>T (p.Ser1452Cys) from the father. Although RAAS blockade was initiated for the older sister and brother when their renal function was already impaired, it did not attenuate disease progression. In the youngest brother, RAAS blockade was initiated during normal renal function stage. After the initiation, his renal function has been normal with the very mild proteinuria to date at the age of 17 years. We propose that in Alport syndrome, RAAS blockade should be initiated earlier than renal function is impaired.

Hemodynamic and proinflammatory actions of endothelin-1 in guinea pig small intestine submucosal microcirculation.

PubMed

King-VanVlack, C E; Mewburn, J D; Chapler, C K; MacDonald, P H

2003-06-01

The hemodynamic and proinflammatory effects of endothelin-1 (ET-1) in proximal (1st/2nd order) and terminal (3rd/4th order) arterioles and venules were examined in small intestine submucosa of anesthetized guinea pigs. Vessel diameter (D), red blood cell velocity, and blood flow (Q) were determined in eight proximal and eight terminal microvessels before and at 20 min of ET-1 suffusion (10(-10), 10(-9), and 10(-8) M) and then with endothelin-A (ET(A))-receptor blockade with BQ-123 (10(-5) M). This protocol was repeated with platelet-activating factor (PAF) inhibition (WEB-2086, 1.0 mg/kg iv; n = 16). The ET-1-mediated microvascular responses were also examined with endothelin-B (ET(B))-receptor blockade using BQ-788 (10(-5) M; n = 11) alone or with ET(A+B)-receptor blockade with BQ-123 + BQ-788 (n = 10). Microvascular permeability was assessed by FITC-albumin (25 mg/kg iv) extravasation in seven series: 1) buffered modified Krebs solution suffusion (n = 6), 2) histamine suffusion (HIS; 10(-3) M, n = 5), 3) ET-1 suffusion (10(-8) M, n = 5), 4) BQ-123 (10(-5) M) plus ET-1 suffusion (n = 5), 5) PAF inhibition before ET-1 suffusion (n = 5), 6) histamine-1 (H1)-receptor blockade (diphenhydramine, 20 mg/kg iv) before ET-1 suffusion (n = 5), and 7) ET(B)-receptor blockade before (BQ-788 10(-5) M; n = 3) or with ET-1 suffusion (n = 3). D and Q decreased at 10(-8) M ET-1 and returned to control values with BQ-123 and BQ-123+BQ788 but not with BQ-788 in proximal microvessels. D did not change in terminal microvessels with ET-1 (10(-8) M) but decreased with BQ-788 and increased with BQ-123. PAF inhibition did not affect the D and Q responses of proximal microvessels to ET-1 but prevented the fall in Q in terminal microvessels with ET-1. ET-1 increased vascular permeability to approximately 1/3 of that with HIS; this response was prevented with BQ-123 and WEB-2086 but not with H1-receptor blockade. This is the first evidence that submucosal terminal microvessel flow is reduced with ET-1 independent of vessel diameter changes and that this response is associated with increased microvascular permeability mediated via ET(A)-receptor stimulation and PAF activation.

Combination use of medicines from two classes of renin-angiotensin system blocking agents: risk of hyperkalemia, hypotension, and impaired renal function.

PubMed

Esteras, Raquel; Perez-Gomez, Maria Vanessa; Rodriguez-Osorio, Laura; Ortiz, Alberto; Fernandez-Fernandez, Beatriz

2015-08-01

European and United States regulatory agencies recently issued warnings against the use of dual renin-angiotensin system (RAS) blockade therapy through the combined use of angiotensin-converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs) or aliskiren in any patient, based on absence of benefit for most patients and increased risk of hyperkalemia, hypotension, and renal failure. Special emphasis was made not to use these combinations in patients with diabetic nephropathy. The door was left open to therapy individualization, especially for patients with heart failure, when the combined use of an ARB and ACEI is considered absolutely essential, although renal function, electrolytes and blood pressure should be closely monitored. Mineralocorticoid receptor antagonists were not affected by this warning despite increased risk of hyperkalemia. We now critically review the risks associated with dual RAS blockade and answer the following questions: What safety issues are associated with dual RAS blockade? Can the safety record of dual RAS blockade be improved? Is it worth trying to improve the safety record of dual RAS blockade based on the potential benefits of the combination? Is dual RAS blockade dead? What is the role of mineralocorticoid antagonists in combination with other RAS blocking agents: RAAS blockade?

Concomitant manipulation of murine NMDA- and AMPA-receptors to produce pro-cognitive drug effects in mice.

PubMed

Vignisse, Julie; Steinbusch, Harry W M; Grigoriev, Vladimir; Bolkunov, Alexei; Proshin, Alexey; Bettendorff, Lucien; Bachurin, Sergey; Strekalova, Tatyana

2014-02-01

Bifunctional drug therapy targeting distinct receptor signalling systems can generate increased efficacy at lower concentrations compared to monofunctional therapy. Non-competitive blockade of the NMDA receptors or the potentiation of AMPA receptors is well documented to result in memory enhancement. Here, we compared the efficacy of the low-affinity NMDA receptor blocker memantine or the positive modulator of AMPA receptor QXX (in C57BL/6J at 1 or 5mg/kg, ip) with new derivatives of isothiourea (0.5-1 mg/kg, ip) that have bifunctional efficacy. Low-affinity NMDA blockade by these derivatives was achieved by introducing greater flexibility into the molecule, and AMPA receptor stimulation was produced by a sulfamide-containing derivative of isothiourea. Contextual learning was examined in a step-down avoidance task and extinction of contextual memory was studied in a fear-conditioning paradigm. Memantine enhanced contextual learning while QXX facilitated memory extinction; both drugs were effective at 5 mg/kg. The new derivative IPAC-5 elevated memory scores in both tasks at the dose 0.5 mg/kg and exhibited the lowest IC₅₀ values of NMDA receptor blockade and highest potency of AMPA receptor stimulation. Thus, among the new drugs tested, IPAC-5 replicated the properties of memantine and QXX in one administration with increased potency. Our data suggest that a concomitant manipulation of NMDA- and AMPA-receptors results in pro-cognitive effects and supports the concept bifunctional drug therapy as a promising strategy to replace monofunctional therapies with greater efficacy and improved compliance. Copyright © 2013 Elsevier B.V. and ECNP. All rights reserved.

Optimum AT1 receptor-neprilysin inhibition has superior cardioprotective effects compared with AT1 receptor blockade alone in hypertensive rats.

PubMed

Roksnoer, Lodi C W; van Veghel, Richard; de Vries, René; Garrelds, Ingrid M; Bhaggoe, Usha M; Friesema, Edith C H; Leijten, Frank P J; Poglitsch, Marko; Domenig, Oliver; Clahsen-van Groningen, Marian C; Hoorn, Ewout J; Jan Danser, A H; Batenburg, Wendy W

2015-07-01

Neprilysin inhibitors prevent the breakdown of bradykinin and natriuretic peptides, promoting vasodilation and natriuresis. However, they also increase angiotensin II and endothelin-1. Here we studied the effects of a low and a high dose of the neprilysin inhibitor thiorphan on top of AT1 receptor blockade with irbesartan versus vehicle in TGR(mREN2)27 rats with high renin hypertension. Mean arterial blood pressure was unaffected by vehicle or thiorphan alone. Irbesartan lowered blood pressure, but after 7 days pressure started to increase again. Low- but not high-dose thiorphan prevented this rise. Only during exposure to low-dose thiorphan plus irbesartan did heart weight/body weight ratio, cardiac atrial natriuretic peptide expression, and myocyte size decrease significantly. Circulating endothelin-1 was not affected by low-dose thiorphan with or without irbesartan, but increased after treatment with high-dose thiorphan plus irbesartan. This endothelin-1 rise was accompanied by an increase in renal sodium-hydrogen exchanger 3 protein abundance, and an upregulation of constrictor vascular endothelin type B receptors. Consequently, the endothelin type B receptor antagonist BQ788 no longer enhanced endothelin-1-induced vasoconstriction (indicative of endothelin type B receptor-mediated vasodilation), but prevented it. Thus, optimal neprilysin inhibitor dosing reveals additional cardioprotective effects on top of AT1 receptor blockade in renin-dependent hypertension.

Endocannabinoids as mediators in the heart: a potential target for therapy of remodelling after myocardial infarction?

PubMed Central

Hiley, C Robin; Ford, William R

2003-01-01

Endocannabinoid production by platelets and macrophages is increased in circulatory shock. This may be protective of the cardiovascular system as blockade of CB1 cannabinoid receptors exacerbates endothelial dysfunction in haemorrhagic and endotoxin shock and reduces survival. Now evidence suggests that blockade of CB1 receptors starting 24 h after myocardial infarction in rats has a deleterious effect on cardiac performance, while use of a nonselective cannabinoid receptor agonist prevents hypotension and reduces endothelial dysfunction, although left ventricular end diastolic pressure is elevated. Cannabinoids and endocannabinoid systems may therefore present useful targets for therapy following myocardial infarction. PMID:12711614

Attenuation of Persistent Experimental Pancreatitis Pain by a Bradykinin B2 Receptor Antagonist

PubMed Central

Chen, Qingmin; Vera-Portocarrero, Louis P.; Ossipov, Michael H.; Vardanyan, Marina; Lai, Josephine; Porreca, Frank

2017-01-01

Objective The role of bradykinin (BK) receptors in activating and sensitizing peripheral nociceptors is well known. Recently, we showed that spinal dynorphin was pronociceptive through direct or indirect BK receptor activation. Here, we explored the potential role of BK receptors in pain associated with persistent pancreatitis in rats. Methods Experimental pancreatitis and abdominal hypersensitivity were induced by intravenous administrations of dibutyltin dichloride (DBTC). [des-Arg9-Leu8]BK (B1 antagonist) and HOE 140 (B2 antagonist) were given by intraperitoneal or intrathecal injection. Dynorphin antiserum was given intrathecally. Reverse transcription–polymerase chain reaction was used to detect spinal mRNA for BK receptors. Results Dibutyltin dichloride–induced pancreatitis upregulated B1 and B2 mRNA in the thoracic dorsal root ganglion and B2, but not B1, in the pancreas. No changes in spinal B1 or B2 mRNA were observed. Intraperitoneal or intrathecal administration of HOE 140 dose dependently abolished DBTC-induced abdominal hypersensitivity, whereas [des-Arg9-Leu8]BK was without effect by either route of administration. Antiserum to dynorphin (intrathecal) abolished DBTC-induced hypersensitivity. Conclusions These results suggest that blockade of peripheral or spinal BK B2 receptors may be an effective approach for diminishing pain associated with pancreatitis. Moreover, it is suggested that spinal dynorphin may maintain pancreatitis pain through direct or indirect activation of BK B2 receptors in the spinal cord. PMID:20531238

Ultralow concentrations of bupivacaine exert anti-inflammatory effects on inflammation-reactive astrocytes

PubMed Central

Block, Linda; Jörneberg, Per; Björklund, Ulrika; Westerlund, Anna; Biber, Björn; Hansson, Elisabeth

2013-01-01

Bupivacaine is a widely used, local anesthetic agent that blocks voltage-gated Na+ channels when used for neuro-axial blockades. Much lower concentrations of bupivacaine than in normal clinical use, < 10−8 m, evoked Ca2+ transients in astrocytes from rat cerebral cortex, that were inositol trisphosphate receptor-dependent. We investigated whether bupivacaine exerts an influence on the Ca2+ signaling and interleukin-1β (IL-1β) secretion in inflammation-reactive astrocytes when used at ultralow concentrations, < 10−8 m. Furthermore, we wanted to determine if bupivacaine interacts with the opioid-, 5-hydroxytryptamine- (5-HT) and glutamate-receptor systems. With respect to the μ-opioid- and 5-HT-receptor systems, bupivacaine restored the inflammation-reactive astrocytes to their normal non-inflammatory levels. With respect to the glutamate-receptor system, bupivacaine, in combination with an ultralow concentration of the μ-opioid receptor antagonist naloxone and μ-opioid receptor agonists, restored the inflammation-reactive astrocytes to their normal non-inflammatory levels. Ultralow concentrations of bupivacaine attenuated the inflammation-induced upregulation of IL-1β secretion. The results indicate that bupivacaine interacts with the opioid-, 5-HT- and glutamate-receptor systems by affecting Ca2+ signaling and IL-1β release in inflammation-reactive astrocytes. These results suggest that bupivacaine may be used at ultralow concentrations as an anti-inflammatory drug, either alone or in combination with opioid agonists and ultralow concentrations of an opioid antagonist. PMID:24083665

α2-adrenergic blockade mimics the enhancing effect of chronic stress on breast cancer progression

PubMed Central

Lamkin, Donald M.; Sung, Ha Yeon; Yang, Gyu Sik; David, John M.; Ma, Jeffrey C.Y.; Cole, Steve W.; Sloan, Erica K.

2014-01-01

Experimental studies in preclinical mouse models of breast cancer have shown that chronic restraint stress can enhance disease progression by increasing catecholamine levels and subsequent signaling of β-adrenergic receptors. Catecholamines also signal α-adrenergic receptors, and greater α-adrenergic signaling has been shown to promote breast cancer in vitro and in vivo. However, antagonism of α-adrenergic receptors can result in elevated catecholamine levels, which may increase β-adrenergic signaling, because pre-synaptic α2-adrenergic receptors mediate an autoinhibition of sympathetic transmission. Given these findings, we examined the effect of α-adrenergic blockade on breast cancer progression under non-stress and stress conditions (chronic restraint) in an orthotopic mouse model with MDA-MB-231HM cells. Chronic restraint increased primary tumor growth and metastasis to distant tissues as expected, and non-selective α-adrenergic blockade by phentolamine significantly inhibited those effects. However, under non-stress conditions, phentolamine increased primary tumor size and distant metastasis. Sympatho-neural gene expression for catecholamine biosynthesis enzymes was elevated by phentolamine under non-stress conditions, and the non-selective β-blocker propranolol inhibited the effect of phentolamine on breast cancer progression. Selective α2-adrenergic blockade by efaroxan also increased primary tumor size and distant metastasis under non-stress conditions, but selective α1-adrenergic blockade by prazosin did not. These results are consistent with the hypothesis that α2-adrenergic signaling can act through an autoreceptor mechanism to inhibit sympathetic catecholamine release and, thus, modulate established effects of β-adrenergic signaling on tumor progression-relevant biology. PMID:25462899

Pharmacological interference with metabotropic glutamate receptor subtype 7 but not subtype 5 differentially affects within- and between-session extinction of Pavlovian conditioned fear.

PubMed

Toth, Iulia; Dietz, Monika; Peterlik, Daniel; Huber, Sabine E; Fendt, Markus; Neumann, Inga D; Flor, Peter J; Slattery, David A

2012-03-01

Fear extinction is defined as the attenuation of a conditioned-fear memory by re-exposing animals to the conditioned stimulus without the aversive stimulus. This process is known to be effectively enhanced via administration of D-cycloserine (DCS), a partial NMDA-receptor agonist. However, other glutamatergic mechanisms, such as interference with metabotropic glutamate receptor (mGluR) subtypes 5 and 7 in the extinction of aversive memories are insufficiently understood. Using the allosteric mGluR5 receptor antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP), the mGluR7 allosteric agonist N,N'-dibenzyhydryl-ethane-1,2-diamine dihydrochloride (AMN082), and DCS for comparison, we aimed to study how pharmacological blockade of mGluR5 and activation of mGluR7 influenced within- and between-session conditioned-fear extinction training and extinction retention in rats. We show that when injected before extinction training, mGluR7 activation with AMN082 enhanced freezing and thereby attenuated within-session fear extinction, whereas both DCS and the mGluR5 receptor antagonist MPEP had no effect on this process. However, these differential drug effects were not long lasting, as no difference in extinction retention were observed 24 h later. Therefore, we assessed whether the compounds affect 24 h consolidation of extinction training following incomplete extinction training (between-session extinction). Similar to DCS, AMN082- but not MPEP-treated rats showed facilitated extinction retention, as exhibited by decreased freezing. Finally, using fluoxetine, we provide evidence that the effect of AMN082 on between-session extinction retention is most likely not via increasing 5-HT transmission. These findings demonstrate that mGluR7 activation differentially modulates conditioned-fear extinction, in dependence on the protocol employed, and suggests drugs with AMN082-like mechanisms as potential add-on drugs following exposure-based psychotherapy for fear-related human disorders. Copyright © 2011 Elsevier Ltd. All rights reserved.

Interaction between vasopressin and angiotensin II in vivo and in vitro: effect on aquaporins and urine concentration

PubMed Central

Wang, Weidong; Li, Chunling; Summer, Sandra; Falk, Sandor

2010-01-01

The study was undertaken to examine the potential cross talk between vasopressin and angiotensin II (ANG II) intracellular signaling pathways. We investigated in vivo and in vitro whether vasopressin-induced water reabsorption could be attenuated by ANG II AT1 receptor blockade (losartan). On a low-sodium diet (0.5 meq/day) dDAVP-treated animals with or without losartan exhibited comparable renal function [creatinine clearance 1.2 ± 0.1 in dDAVP+losartan (LSDL) vs. 1.1 ± 0.1 ml·100 g−1·day−1 in dDAVP alone (LSD), P > 0.05] and renal blood flow (6.3 ± 0.5 in LSDL vs. 6.8 ± 0.5 ml/min in LSD, P > 0.05). The urine output, however, was significantly increased in LSDL (2.5 ± 0.2 vs. 1.8 ± 0.2 ml·100 g−1·day−1, P < 0.05) in association with decreased urine osmolality (2,600 ± 83 vs. 3,256 ± 110 mosmol/kgH2O, P < 0.001) compared with rats in LSD. Immunoblotting revealed significantly decreased expression of medullary AQP2 (146 ± 6 vs. 176 ± 10% in LSD, P < 0.01), p-AQP2 (177 ± 13 vs. 214 ± 12% in LSD, P < 0.05), and AQP3 (134 ± 14 vs. 177 ± 11% in LSD, P < 0.05) in LSDL compared with LSD. The expressions of AQP1, the α1- and γ-subunits of Na-K-ATPase, and the Na-K-2Cl cotransporter were not different among groups. In vitro studies showed that ANG II or dDAVP treatment was associated with increased AQP2 expression and cAMP levels, which were potentiated by cotreatment with ANG II and dDAVP and were inhibited by AT1 blockade. In conclusion, ANG II AT1 receptor blockade in dDAVP-treated rats on a low-salt diet was associated with decreased urine concentration and decreased inner medullary AQP2, p-AQP2, and AQP3 expression, suggesting that AT1 receptor activation plays a significant role in regulating aquaporin expression and modulating urine concentration in vivo. Studies in collecting duct cells were confirmatory. PMID:20576679

Beneficial Effects of the Activation of the Angiotensin-(1–7) Mas Receptor in a Murine Model of Adriamycin-Induced Nephropathy

PubMed Central

Silveira, Kátia Daniela; Barroso, Lívia Corrêa; Vieira, Angélica Thomáz; Cisalpino, Daniel; Lima, Cristiano Xavier; Bader, Michael; Arantes, Rosa Maria Esteves; dos Santos, Robson Augusto Souza

2013-01-01

Angiotensin-(1–7) [Ang-(1–7)] is a biologically active heptapeptide that may counterbalance the physiological actions of angiotensin II (Ang II) within the renin-angiotensin system (RAS). Here, we evaluated whether activation of the Mas receptor with the oral agonist, AVE 0991, would have renoprotective effects in a model of adriamycin (ADR)-induced nephropathy. We also evaluated whether the Mas receptor contributed for the protective effects of treatment with AT1 receptor blockers. ADR (10 mg/kg) induced significant renal injury and dysfunction that was maximal at day 14 after injection. Treatment with the Mas receptor agonist AVE 0991 improved renal function parameters, reduced urinary protein loss and attenuated histological changes. Renoprotection was associated with reduction in urinary levels of TGF-β. Similar renoprotection was observed after treatment with the AT1 receptor antagonist, Losartan. AT1 and Mas receptor mRNA levels dropped after ADR administration and treatment with losartan reestablished the expression of Mas receptor and increased the expression of ACE2. ADR-induced nephropathy was similar in wild type (Mas+/+) and Mas knockout (Mas −/−) mice, suggesting there was no endogenous role for Mas receptor activation. However, treatment with Losartan was able to reduce renal injury only in Mas+/+, but not in Mas −/− mice. Therefore, these findings suggest that exogenous activation of the Mas receptor protects from ADR-induced nephropathy and contributes to the beneficial effects of AT1 receptor blockade. Medications which target specifically the ACE2/Ang-(1–7)/Mas axis may offer new therapeutic opportunities to treat human nephropathies. PMID:23762470

Dopamine D2-receptor blockade enhances decoding of prefrontal signals in humans.

PubMed

Kahnt, Thorsten; Weber, Susanna C; Haker, Helene; Robbins, Trevor W; Tobler, Philippe N

2015-03-04

The prefrontal cortex houses representations critical for ongoing and future behavior expressed in the form of patterns of neural activity. Dopamine has long been suggested to play a key role in the integrity of such representations, with D2-receptor activation rendering them flexible but weak. However, it is currently unknown whether and how D2-receptor activation affects prefrontal representations in humans. In the current study, we use dopamine receptor-specific pharmacology and multivoxel pattern-based functional magnetic resonance imaging to test the hypothesis that blocking D2-receptor activation enhances prefrontal representations. Human subjects performed a simple reward prediction task after double-blind and placebo controlled administration of the D2-receptor antagonist amisulpride. Using a whole-brain searchlight decoding approach we show that D2-receptor blockade enhances decoding of reward signals in the medial orbitofrontal cortex. Examination of activity patterns suggests that amisulpride increases the separation of activity patterns related to reward versus no reward. Moreover, consistent with the cortical distribution of D2 receptors, post hoc analyses showed enhanced decoding of motor signals in motor cortex, but not of visual signals in visual cortex. These results suggest that D2-receptor blockade enhances content-specific representations in frontal cortex, presumably by a dopamine-mediated increase in pattern separation. These findings are in line with a dual-state model of prefrontal dopamine, and provide new insights into the potential mechanism of action of dopaminergic drugs. Copyright © 2015 the authors 0270-6474/15/354104-08$15.00/0.

Long-term AT1 receptor blockade improves metabolic function and provides renoprotection in Fischer-344 rats.

PubMed

Gilliam-Davis, Shea; Payne, Valerie S; Kasper, Sherry O; Tommasi, Ellen N; Robbins, Michael E; Diz, Debra I

2007-09-01

Fischer-344 (F344) rats exhibit proteinuria and insulin resistance in the absence of hypertension as they age. We determined the effects of long-term (1 yr) treatment with the angiotensin (ANG) II type 1 (AT(1)) receptor blocker L-158,809 on plasma and urinary ANG peptide levels, systolic blood pressure (SBP), and indexes of glucose metabolism in 15-mo-old male F344 rats. Young rats at 3 mo of age (n = 8) were compared with two separate groups of older rats: one control group (n = 7) and one group treated with L-158,809 (n = 6) orally (20 mg/l) for 1 yr. SBP was not different between control and treated rats but was higher in young rats. Serum leptin, insulin, and glucose levels were comparable between treated and young rats, whereas controls had higher glucose and leptin with a similar trend for insulin. Plasma ANG I and ANG II were higher in treated than untreated young or older rats, as evidence of effective AT(1) receptor blockade. Urinary ANG II and ANG-(1-7) were higher in controls compared with young animals, and treated rats failed to show age-related increases. Protein excretion was markedly lower in treated and young rats compared with control rats (young: 8 +/- 2 mg/day vs. control: 129 +/- 51 mg/day vs. treated: 9 +/- 3 mg/day, P < 0.05). Long-term AT(1) receptor blockade improves metabolic parameters and provides renoprotection. Differential regulation of systemic and intrarenal (urinary) ANG systems occurs during blockade, and suppression of the intrarenal system may contribute to reduced proteinuria. Thus, insulin resistance, renal injury, and activation of the intrarenal ANG system during early aging in normotensive animals can be averted by renin-ANG system blockade.

The role of aldosterone antagonism agents in diabetic kidney disease.

PubMed

Wombwell, Eric; Naglich, Andrew

2015-03-01

Diabetic kidney disease is a common consequence of the development of diabetes. In the United Kingdom 18-30% of chronic kidney disease cases and 44% of end-stage renal disease cases in the United States have been attributed to complications of diabetic kidney disease. Angiotensin blockade using angiotensin converting enzyme inhibitors or angiotensin receptor blockers is the standard for slowing the progression of diabetic kidney disease. Evidence suggests that aldosterone antagonism added to standard therapy may be beneficial. This paper aims to explore the pathophysiological contribution of aldosterone in diabetic kidney disease and review available literature for aldosterone antagonism through mineralocorticoid receptor blockade. A comprehensive literature search was conducted. Results were analysed and summarised. Nine trials evaluating a total of 535 patients with diabetic kidney disease were identified that evaluated the use of aldosterone antagonists for reducing the signs of diabetic kidney disease. All trials demonstrated a marked decrease in urinary protein excretion when compared to, or added to angiotensin converting enzyme inhibition or angiotensin receptor blockade. The most commonly reported side effect in all of the trials was hyperkalaemia, which occurred in 6.1% of all patients evaluated. Aldosterone antagonists were generally well tolerated in the evaluated patient populations. Aldosterone antagonism may represent a safe and effective complimentary therapy to the use of angiotensin converting enzyme inhibition, or angiotensin receptor blockade, for slowing the progression of diabetic kidney disease. © 2014 European Dialysis and Transplant Nurses Association/European Renal Care Association.

l-phenylalanine modulates gut hormone release and glucose tolerance, and suppresses food intake through the calcium-sensing receptor in rodents.

PubMed

Alamshah, A; Spreckley, E; Norton, M; Kinsey-Jones, J S; Amin, A; Ramgulam, A; Cao, Y; Johnson, R; Saleh, K; Akalestou, E; Malik, Z; Gonzalez-Abuin, N; Jomard, A; Amarsi, R; Moolla, A; Sargent, P R; Gray, G W; Bloom, S R; Murphy, K G

2017-11-01

High-protein diets (HPDs) are associated with greater satiety and weight loss than diets rich in other macronutrients. The exact mechanisms by which HPDs exert their effects are unclear. However, evidence suggests that the sensing of amino acids produced as a result of protein digestion may have a role in appetite regulation and satiety. We investigated the effects of l-phenylalanine (L-Phe) on food intake and glucose homeostasis in rodents. We investigated the effects of the aromatic amino-acid and calcium-sensing receptor (CaSR) agonist l-phenylalanine (L-Phe) on food intake and the release of the gastrointestinal (GI) hormones peptide YY (PYY), glucagon-like peptide-1 (GLP-1) and ghrelin in rodents, and the role of the CaSR in mediating these effects in vitro and in vivo. We also examined the effect of oral l-Phe administration on glucose tolerance in rats. Oral administration of l-Phe acutely reduced food intake in rats and mice, and chronically reduced food intake and body weight in diet-induced obese mice. Ileal l-Phe also reduced food intake in rats. l-Phe stimulated GLP-1 and PYY release, and reduced plasma ghrelin, and also stimulated insulin release and improved glucose tolerance in rats. Pharmacological blockade of the CaSR attenuated the anorectic effect of intra-ileal l-Phe in rats, and l-Phe-induced GLP-1 release from STC-1 and primary L cells was attenuated by CaSR blockade. l-Phe reduced food intake, stimulated GLP-1 and PYY release, and reduced plasma ghrelin in rodents. Our data provide evidence that the anorectic effects of l-Phe are mediated via the CaSR, and suggest that l-Phe and the CaSR system in the GI tract may have therapeutic utility in the treatment of obesity and diabetes. Further work is required to determine the physiological role of the CaSR in protein sensing in the gut, and the role of this system in humans.

[Combined blockade of AMPA- and NMDA-receptors has maximum effect to eliminate development of pentylenetetrazole-induced kindling in rats].

PubMed

Serdiuk, S E; Gmiro, V E; Veselkina, O S

2013-05-01

Peroral chronic administration the standard antiepileptic drug sodium valproate in a dose of 200 mg/kg eliminates development of generalized clonic-tonic pentylenetetrazol kindling seizures in 100% of rats, but only in 57% of rats this treatment prevents clonic kindling seizures. In the specified dose sodium valproate decreases in 1.7 times average severity of pentylenetetrazol kindling seizures compare with control. IEM-2121, causing combined blockade of NMDA- and AMPA-glutamate receptors, as well as IEM-1676, which also blocks AMPA-, NMDA- and N-cholinoreceptors, both after peroral chronic administration in a doses 10 mg/kg and 20 mg/kg accordingly, possess higher, than sodium valproate, anticonvulsant activity because reduce average severity of pentylenetetrazol kindling seizures in 2.4-2.7 times in comparison with control and prevents clonic kindling seizures in 87% of rats. Combined blockade of AMPA- and NMDA-receptors and perhars N-cholinoreceptors has maximum effect to eliminate epileptogenesis both clonic, and clonic-tonic pentylenetetrazol kindling seizures.

Do all β-blockers attenuate the excess hematopoietic progenitor cell mobilization from the bone marrow following trauma/hemorrhagic shock?

PubMed

Pasupuleti, Latha V; Cook, Kristin M; Sifri, Ziad C; Alzate, Walter D; Livingston, David H; Mohr, Alicia M

2014-04-01

Severe injury results in increased mobilization of hematopoietic progenitor cells (HPC) from the bone marrow (BM) to sites of injury, which may contribute to persistent BM dysfunction after trauma. Norepinephrine is a known inducer of HPC mobilization, and nonselective β-blockade with propranolol has been shown to decrease mobilization after trauma and hemorrhagic shock (HS). This study will determine the role of selective β-adrenergic receptor blockade in HPC mobilization in a combined model of lung contusion (LC) and HS. Male Sprague-Dawley rats were subjected to LC, followed by 45 minutes of HS. Animals were then randomized to receive atenolol (LCHS + β1B), butoxamine (LCHS + β2B), or SR59230A (LCHS + β3B) immediately after resuscitation and daily for 6 days. Control groups were composed of naive animals. BM cellularity, %HPCs in peripheral blood, and plasma granulocyte-colony stimulating factor levels were assessed at 3 hours and 7 days. Systemic plasma-mediated effects were evaluated in vitro by assessment of BM HPC growth. Injured lung tissue was graded histologically by a blinded reader. The use of β2B or β3B following LCHS restored BM cellularity and significantly decreased HPC mobilization. In contrast, β1B had no effect on HPC mobilization. Only β3B significantly reduced plasma G-CSF levels. When evaluating the plasma systemic effects, both β2B and β3B significantly improved BM HPC growth as compared with LCHS alone. The use of β2 and β3 blockade did not affect lung injury scores. Both β2 and β3 blockade can prevent excess HPC mobilization and BM dysfunction when given after trauma and HS, and the effects seem to be mediated systemically, without adverse effects on subsequent healing. Only treatment with β3 blockade reduced plasma G-CSF levels, suggesting different mechanisms for adrenergic-induced G-CSF release and mobilization of HPCs. This study adds to the evidence that therapeutic strategies that reduce the exaggerated sympathetic stimulation after severe injury are beneficial and reduce BM dysfunction.

Neonatal blockade of GABA-A receptors alters behavioral and physiological phenotypes in adult mice.

PubMed

Salari, Ali-Akbar; Amani, Mohammad

2017-04-01

Gamma-aminobutyric acid (GABA) plays an inhibitory role in the mature brain, and has a complex and bidirectional effect in different parts of the immature brain which affects proliferation, migration and differentiation of neurons during development. There is also increasing evidence suggesting that activation or blockade of the GABA-A receptors during early life can induce brain and behavioral abnormalities in adulthood. We investigated whether neonatal blockade of the GABA-A receptors by bicuculline can alter anxiety- and depression-like behaviors, body weight, food intake, corticosterone and testosterone levels in adult mice (postnatal days 80-95). To this end, neonatal mice were treated with either DMSO or bicuculline (70, 150 and 300μg/kg) during postnatal days 7, 9 and 11. When grown to adulthood, mice were exposed to behavioral tests to measure anxiety- (elevated plus-maze and light-dark box) and depression-like behaviors (tail suspension test and forced swim test). Stress-induced serum corticosterone and testosterone levels, body weight and food intake were also evaluated. Neonatal bicuculline exposure at dose of 300μg/kg decreased anxiety-like behavior, stress-induced corticosterone levels and increased testosterone levels, body weight and food intake, without significantly influencing depression-like behavior in adult male mice. However, no significant changes in these parameters were observed in adult females. These findings suggest that neonatal blockade of GABA-A receptors affects anxiety-like behavior, physiological and hormonal parameters in a sex-dependent manner in mice. Taken together, these data corroborate the concept that GABA-A receptors during early life have an important role in programming neurobehavioral phenotypes in adulthood. Copyright © 2017 ISDN. Published by Elsevier Ltd. All rights reserved.

The Influence of the CB1 Receptor Ligands on the Schizophrenia-Like Effects in Mice Induced by MK-801.

PubMed

Kruk-Slomka, Marta; Budzynska, Barbara; Slomka, Tomasz; Banaszkiewicz, Izabela; Biala, Grazyna

2016-11-01

A growing body of psychiatric research has emerged, focusing on the role of endocannabinoid system in psychiatric disorders. For example, the endocannabinoid system, via cannabinoid CB (CB1 and CB2) receptors, is able to control the function of many receptors, such as N-methyl-D-aspartate (NMDA) receptors connected strictly with psychosis or other schizophrenia-associated symptoms. The aim of the present research was to investigate the impact of the CB1 receptor ligands on the symptoms typical for schizophrenia. We provoked psychosis-like effects in mice by an acute administration of NMDA receptor antagonist, MK-801 (0.1-0.6 mg/kg). An acute administration of MK-801 induced psychotic symptoms, manifested in the increase in locomotor activity (hyperactivity), measured in actimeters, as well as the memory impairment, assessed in the passive avoidance task. We revealed that an acute injection of CB1 receptor agonist, oleamide (5-20 mg/kg), had no influence on the short- and long-term memory-related disturbances, as well as on the hyperlocomotion in mice, provoking by an acute MK-801. In turn, an amnestic effects or hyperactivity induced by an acute MK-801 was attenuated by an acute administration of AM 251 (0.25-3 mg/kg), a CB1 receptor antagonist. The present findings confirm that endocannabinoid system is able to modify a variety of schizophrenia-like responses, including the cognitive disturbances and hyperlocomotion in mice. Antipsychotic-like effects induced by CB1 receptor antagonist, obtained in our research, confirm the potential effect of CB1 receptor blockade and could have important therapeutic implications on clinical settings, in the future.

Blockade of NMDA receptors prevents analgesic tolerance to repeated transcutaneous electrical nerve stimulation (TENS) in rats

PubMed Central

Hingne, Priyanka M.; Sluka, Kathleen A.

2008-01-01

Repeated daily application transcutaneous electrical nerve stimulation (TENS) results in tolerance, at spinal opioid receptors, to the anti-hyperalgesia produced by TENS. Since N-Methyl-D-Aspartate (NMDA) receptor antagonists prevent analgesic tolerance to opioid agonists we hypothesized that blockade of NMDA receptors will prevent tolerance to TENS. In rats with knee joint inflammation, TENS was applied for 20 minute daily at high frequency (100 Hz), low frequency (4 Hz), or sham TENS. Rats were treated with the NMDA antagonist MK-801 (0.01 mg/kg-0.1 mg/kg) or vehicle daily before TENS. Paw withdrawal thresholds were tested before and after inflammation, and before and after TENS treatment for 4 days. On day 1 TENS reversed the decreased mechanical withdrawal threshold induced by joint inflammation. On day 4 TENS had no effect on the decreased withdrawal threshold in the group treated with vehicle demonstrating development of tolerance. However, in the group treated with 0.1 mg/kg MK-801, TENS significantly reversed the mechanical withdrawal thresholds on day 4 demonstrating that tolerance did not develop. Vehicle treated animals developed cross-tolerance at spinal opioid receptors. Treatment with MK-801 reversed this cross-tolerance at spinal opioid receptors. In summary, blockade of NMDA receptors prevents analgesic tolerance to daily TENS by preventing tolerance at spinal opioid receptors. Perspective Tolerance observed to the clinical treatment of TENS could be prevented by administration of pharmaceutical agents with NMDA receptors activity such as ketamine or dextromethorphan. PMID:18061543

IGF-1 Receptor Differentially Regulates Spontaneous and Evoked Transmission via Mitochondria at Hippocampal Synapses

PubMed Central

Gazit, Neta; Vertkin, Irena; Shapira, Ilana; Helm, Martin; Slomowitz, Edden; Sheiba, Maayan; Mor, Yael; Rizzoli, Silvio; Slutsky, Inna

2016-01-01

Summary The insulin-like growth factor-1 receptor (IGF-1R) signaling is a key regulator of lifespan, growth, and development. While reduced IGF-1R signaling delays aging and Alzheimer’s disease progression, whether and how it regulates information processing at central synapses remains elusive. Here, we show that presynaptic IGF-1Rs are basally active, regulating synaptic vesicle release and short-term plasticity in excitatory hippocampal neurons. Acute IGF-1R blockade or transient knockdown suppresses spike-evoked synaptic transmission and presynaptic cytosolic Ca2+ transients, while promoting spontaneous transmission and resting Ca2+ level. This dual effect on transmitter release is mediated by mitochondria that attenuate Ca2+ buffering in the absence of spikes and decrease ATP production during spiking activity. We conclude that the mitochondria, activated by IGF-1R signaling, constitute a critical regulator of information processing in hippocampal neurons by maintaining evoked-to-spontaneous transmission ratio, while constraining synaptic facilitation at high frequencies. Excessive IGF-1R tone may contribute to hippocampal hyperactivity associated with Alzheimer’s disease. Video Abstract PMID:26804996

Responses to dehydration in the one-humped camel and effects of blocking the renin-angiotensin system.

PubMed

Ali, Mahmoud Alhaj; Adem, Abdu; Chandranath, Irwin S; Benedict, Sheela; Pathan, Javed Y; Nagelkerke, Nicolas; Nyberg, Fred; Lewis, Lynley K; Yandle, Tim G; Nicholls, Gary M; Frampton, Chris M; Kazzam, Elsadig

2012-01-01

Our objectives were to compare the levels of circulating electrolytes, hormones, and renal function during 20 days of dehydration in camels versus the level in non-dehydrated camels and to record the effect of blocking angiotensin II AT1 receptors with losartan during dehydration. Dehydration induced significant increments in serum sodium, creatinine, urea, a substantial fall in body weight, and a doubling in plasma arginine vasopressin (AVP) levels. Plasma aldosterone, however, was unaltered compared with time-matched controls. Losartan significantly enhanced the effect of dehydration to reduce body weight and increase serum levels of creatinine and urea, whilst also impairing the rise in plasma AVP and reducing aldosterone levels. We conclude that dehydration in the camel induces substantial increments in serum sodium, creatinine, urea and AVP levels; that aldosterone levels are altered little by dehydration; that blockade of angiotensin II type 1 receptors enhances the dehydration-induced fall in body weight and increase in serum creatinine and urea levels whilst reducing aldosterone and attenuating the rise in plasma AVP.

Responses to Dehydration in the One-Humped Camel and Effects of Blocking the Renin-Angiotensin System

PubMed Central

Ali, Mahmoud Alhaj; Adem, Abdu; Chandranath, Irwin S.; Benedict, Sheela; Pathan, Javed Y.; Nagelkerke, Nicolas; Nyberg, Fred; Lewis, Lynley K.; Yandle, Tim G.; Nicholls, Gary M.; Frampton, Chris M.; Kazzam, Elsadig

2012-01-01

Our objectives were to compare the levels of circulating electrolytes, hormones, and renal function during 20 days of dehydration in camels versus the level in non-dehydrated camels and to record the effect of blocking angiotensin II AT1 receptors with losartan during dehydration. Dehydration induced significant increments in serum sodium, creatinine, urea, a substantial fall in body weight, and a doubling in plasma arginine vasopressin (AVP) levels. Plasma aldosterone, however, was unaltered compared with time-matched controls. Losartan significantly enhanced the effect of dehydration to reduce body weight and increase serum levels of creatinine and urea, whilst also impairing the rise in plasma AVP and reducing aldosterone levels. We conclude that dehydration in the camel induces substantial increments in serum sodium, creatinine, urea and AVP levels; that aldosterone levels are altered little by dehydration; that blockade of angiotensin II type 1 receptors enhances the dehydration-induced fall in body weight and increase in serum creatinine and urea levels whilst reducing aldosterone and attenuating the rise in plasma AVP. PMID:22624009

Neuroleptic-induced catalepsy: a D2 blockade phenomenon?

PubMed

Klemm, W R

1985-12-01

Typical neuroleptics, such as haloperidol, are cataleptogenic. But since such drugs block both D1 and D2 receptors, it is not clear if there is a differential receptor role in catalepsy. To test this issue in a mouse model of catalepsy, these experiments tested molindone, a D2-blocking neuroleptic with almost no ability to block D1 receptors. If D1 receptor blockade is necessary for catalepsy, molindone should not cause catalepsy. But molindone was cataleptogenic, albeit less potent than haloperidol. There was also a "training effect" with haloperidol, but not saline or molindone, in that the catalepsy produced by 5 mg/kg of haloperidol was much greater when tests were performed repeatedly at short intervals after injection. Concurrent administration of apomorphine (4 or 8 mg/kg) markedly potentiated haloperidol catalepsy, but had no effect on molindone catalepsy. Such results are not readily interpretable solely in terms of current concepts of D1 and D2 receptors.

Pharmacological Analysis of Ionotropic Glutamate Receptor Function in Neuronal Circuits of the Zebrafish Olfactory Bulb

PubMed Central

Tabor, Rico; Friedrich, Rainer W.

2008-01-01

Although synaptic functions of ionotropic glutamate receptors in the olfactory bulb have been studied in vitro, their roles in pattern processing in the intact system remain controversial. We therefore examined the functions of ionotropic glutamate receptors during odor processing in the intact olfactory bulb of zebrafish using pharmacological manipulations. Odor responses of mitral cells and interneurons were recorded by electrophysiology and 2-photon Ca2+ imaging. The combined blockade of AMPA/kainate and NMDA receptors abolished odor-evoked excitation of mitral cells. The blockade of AMPA/kainate receptors alone, in contrast, increased the mean response of mitral cells and decreased the mean response of interneurons. The blockade of NMDA receptors caused little or no change in the mean responses of mitral cells and interneurons. However, antagonists of both receptor types had diverse effects on the magnitude and time course of individual mitral cell and interneuron responses and, thus, changed spatio-temporal activity patterns across neuronal populations. Oscillatory synchronization was abolished or reduced by AMPA/kainate and NMDA receptor antagonists, respectively. These results indicate that (1) interneuron responses depend mainly on AMPA/kainate receptor input during an odor response, (2) interactions among mitral cells and interneurons regulate the total olfactory bulb output activity, (3) AMPA/kainate receptors participate in the synchronization of odor-dependent neuronal ensembles, and (4) ionotropic glutamate receptor-containing synaptic circuits shape odor-specific patterns of olfactory bulb output activity. These mechanisms are likely to be important for the processing of odor-encoding activity patterns in the olfactory bulb. PMID:18183297

The ERα-PI3K Cascade in Proopiomelanocortin Progenitor Neurons Regulates Feeding and Glucose Balance in Female Mice

PubMed Central

Zhu, Liangru; Xu, Pingwen; Cao, Xuehong; Yang, Yongjie; Hinton, Antentor Othrell; Xia, Yan; Saito, Kenji; Yan, Xiaofeng; Zou, Fang; Ding, Hongfang; Wang, Chunmei; Yan, Chunling; Saha, Pradip; Khan, Sohaib A.; Zhao, Jean; Fukuda, Makoto; Tong, Qingchun; Clegg, Deborah J.; Chan, Lawrence

2015-01-01

Estrogens act upon estrogen receptor (ER)α to inhibit feeding and improve glucose homeostasis in female animals. However, the intracellular signals that mediate these estrogenic actions remain unknown. Here, we report that anorexigenic effects of estrogens are blunted in female mice that lack ERα specifically in proopiomelanocortin (POMC) progenitor neurons. These mutant mice also develop insulin resistance and are insensitive to the glucose-regulatory effects of estrogens. Moreover, we showed that propyl pyrazole triol (an ERα agonist) stimulates the phosphatidyl inositol 3-kinase (PI3K) pathway specifically in POMC progenitor neurons, and that blockade of PI3K attenuates propyl pyrazole triol-induced activation of POMC neurons. Finally, we show that effects of estrogens to inhibit food intake and to improve insulin sensitivity are significantly attenuated in female mice with PI3K genetically inhibited in POMC progenitor neurons. Together, our results indicate that an ERα-PI3K cascade in POMC progenitor neurons mediates estrogenic actions to suppress food intake and improve insulin sensitivity. PMID:26375425

The ERα-PI3K Cascade in Proopiomelanocortin Progenitor Neurons Regulates Feeding and Glucose Balance in Female Mice.

PubMed

Zhu, Liangru; Xu, Pingwen; Cao, Xuehong; Yang, Yongjie; Hinton, Antentor Othrell; Xia, Yan; Saito, Kenji; Yan, Xiaofeng; Zou, Fang; Ding, Hongfang; Wang, Chunmei; Yan, Chunling; Saha, Pradip; Khan, Sohaib A; Zhao, Jean; Fukuda, Makoto; Tong, Qingchun; Clegg, Deborah J; Chan, Lawrence; Xu, Yong

2015-12-01

Estrogens act upon estrogen receptor (ER)α to inhibit feeding and improve glucose homeostasis in female animals. However, the intracellular signals that mediate these estrogenic actions remain unknown. Here, we report that anorexigenic effects of estrogens are blunted in female mice that lack ERα specifically in proopiomelanocortin (POMC) progenitor neurons. These mutant mice also develop insulin resistance and are insensitive to the glucose-regulatory effects of estrogens. Moreover, we showed that propyl pyrazole triol (an ERα agonist) stimulates the phosphatidyl inositol 3-kinase (PI3K) pathway specifically in POMC progenitor neurons, and that blockade of PI3K attenuates propyl pyrazole triol-induced activation of POMC neurons. Finally, we show that effects of estrogens to inhibit food intake and to improve insulin sensitivity are significantly attenuated in female mice with PI3K genetically inhibited in POMC progenitor neurons. Together, our results indicate that an ERα-PI3K cascade in POMC progenitor neurons mediates estrogenic actions to suppress food intake and improve insulin sensitivity.

Y1R control of sciatic nerve blood flow in the Wistar Kyoto rat.

PubMed

Twynstra, Jasna; Medeiros, Philip J; Lacefield, James C; Jackson, Dwayne N; Shoemaker, J Kevin

2012-09-01

We hypothesized that neuropeptide Y (NPY) exerts vasoconstrictor properties in sciatic nerve blood supply by a Y1 receptor (Y1R) mechanism. Using Doppler ultrasound (40MHz), we measured blood flow velocity through a sciatic nerve supply artery during infusions of NPY and/or Y1R blockade with BIBP3226 in Wistar Kyoto rats before, and following, ganglionic blockade with Hexamethonium (Hex). Following Hex infusion, mean arterial pressure (baseline: 83±18, Hex: 57±3 mm Hg) was reduced. After 30 min, the index of conductance at the sciatic nerve (velocity/MAP expressed as % baseline) started to increase from 103±35 to 127±39% baseline in the following 30 min (p<0.05). Infusion of NPY (Y1 agonist) minimized this dilatory response (Hex baseline: 99±15, NPY: 104±11% baseline; NS). This NPY-induced attenuation was, in turn, minimized by BIBP3226 (Hex baseline: 73±12, NPY+BIBP3226: 89±14% baseline). Neither NPY nor BIBP3226 infusions without Hex affected the sciatic nerve arterial conductance. We conclude that the late dilation following Hex which is reversed by Y1R activation suggests some level of sympathetic control over sciatic nerve blood flow. Copyright © 2012 Elsevier Inc. All rights reserved.

Effect of clazosentan, a selective endothelin A receptor antagonist, and tezosentan, a dual endothelin A/B antagonist, on pulsatile shear stress induced constriction of the iliac in the anaesthetized pig.

PubMed

Ruane-O'Hora, Therese; Rae, Mark George; Markos, Farouk

2011-08-01

1. The effects of changes in mean and pulsatile shear stress on the diameter of the iliac of the anaesthetized pig were investigated in the presence of clazosentan and tezosentan. 2. A total of 17 pigs were used. Mean shear stress was increased by infusing acetylcholine downstream (2-20 μg/min) through the deep femoral artery. Pulsatile shear stress was enhanced first by injecting varying volumes (1-10 mL) of calcium gluconate (stock 10 mg/mL) directly into the left ventricle. Second, by electrical stimulation of the left sympathetic nerves to the heart (1-16 Hz, 4 min duration, supramaximal voltage). 3. An increase in mean shear stress induced a vasodilation that was not altered significantly by the selective endothelin A antagonist clazosentan (10 mg/kg i.v.). Similarly, the vasoconstriction induced by an increase in pulsatile shear stress brought about by either calcium gluconate injections or left sympathetic nerve stimulation was unaffected by clazosentan. However, tezosentan (10 mg/kg i.v.), significantly attenuated the vasoconstriction induced by an increase in pulsatile shear stress. 4. In conclusion, an increase in pulsatile shear stress causes vasoconstriction of the pig iliac artery, which is attenuated by dual endothelin receptor antagonism, but not by specific endothelin A blockade. © 2011 The Authors. Clinical and Experimental Pharmacology and Physiology © 2011 Blackwell Publishing Asia Pty Ltd.

Incorporation of Immune Checkpoint Blockade into Chimeric Antigen Receptor T Cells (CAR-Ts): Combination or Built-In CAR-T

PubMed Central

Yoon, Dok Hyun; Osborn, Mark J.; Tolar, Jakub; Kim, Chong Jai

2018-01-01

Chimeric antigen receptor (CAR) T cell therapy represents the first U.S. Food and Drug Administration approved gene therapy and these engineered cells function with unprecedented efficacy in the treatment of refractory CD19 positive hematologic malignancies. CAR translation to solid tumors is also being actively investigated; however, efficacy to date has been variable due to tumor-evolved mechanisms that inhibit local immune cell activity. To bolster the potency of CAR-T cells, modulation of the immunosuppressive tumor microenvironment with immune-checkpoint blockade is a promising strategy. The impact of this approach on hematological malignancies is in its infancy, and in this review we discuss CAR-T cells and their synergy with immune-checkpoint blockade. PMID:29364163

Behavioral analysis of the consequences of chronic blockade of NMDA-type glutamate receptors in the early postnatal period in rats.

PubMed

Latysheva, N V; Raevskii, K S

2003-02-01

Considering data on the possible glutamatergic nature of the pathogenesis of schizophrenia, we attempted to model cognitive derangements in animals by chronic blockade of NMDA glutamate receptors. Wistar rats received daily s.c. injections of the non-competitive NMDA glutamate receptor antagonist MK-801 (0.05 mg/kg) from days 7 to day 49 of postnatal life. One day after the antagonist injections given on days 27 and 28 of life, animals of the experimental group showed decreased levels of spontaneous movement and orientational-investigative activity as compared with controls, where there was no change in the elevated locomotor reaction produced in response to the direct action of MK-801. These animals showed decreases in the level of anxiety (on day 40 of life) and derangement in spatial learning with food reinforcement (days 50-54 of life). It is suggested that early neonatal blockade of NMDA glutamate receptors leads to the development in animals of disturbances to situational perception and assessment of incoming sensory information.

Chronic and acute adenosine A2A receptor blockade prevents long-term episodic memory disruption caused by acute cannabinoid CB1 receptor activation.

PubMed

Mouro, Francisco M; Batalha, Vânia L; Ferreira, Diana G; Coelho, Joana E; Baqi, Younis; Müller, Christa E; Lopes, Luísa V; Ribeiro, Joaquim A; Sebastião, Ana M

2017-05-01

Cannabinoid-mediated memory impairment is a concern in cannabinoid-based therapies. Caffeine exacerbates cannabinoid CB 1 receptor (CB 1 R)-induced memory deficits through an adenosine A 1 receptor-mediated mechanism. We now evaluated how chronic or acute blockade of adenosine A 2A receptors (A 2A Rs) affects long-term episodic memory deficits induced by a single injection of a selective CB 1 R agonist. Long-term episodic memory was assessed by the novel object recognition (NOR) test. Mice received an intraperitoneal (i.p.) injection of the CB 1 /CB 2 receptor agonist WIN 55,212-2 (1 mg/kg) immediately after the NOR training, being tested for novelty recognition 24 h later. Anxiety levels were assessed by the Elevated Plus Maze test, immediately after the NOR. Mice were also tested for exploratory behaviour at the Open Field. For chronic A 2A R blockade, KW-6002 (istradefylline) (3 mg/kg/day) was administered orally for 30 days; acute blockade of A 2A Rs was assessed by i.p. injection of SCH 58261 (1 mg/kg) administered either together with WIN 55,212-2 or only 30 min before the NOR test phase. The involvement of CB 1 Rs was assessed by using the CB 1 R antagonist, AM251 (3 mg/kg, i.p.). WIN 55,212-2 caused a disruption in NOR, an action absent in mice also receiving AM251, KW-6002 or SCH 58261 during the encoding/consolidation phase; SCH 58251 was ineffective if present during retrieval only. No effects were detected in the Elevated Plus maze or Open Field Test. The finding that CB 1 R-mediated memory disruption is prevented by antagonism of adenosine A 2A Rs, highlights a possibility to prevent cognitive side effects when therapeutic application of CB 1 R drugs is desired. Copyright © 2017 Elsevier Ltd. All rights reserved.

S100A9 is a novel ligand of EMMPRIN that promotes melanoma metastasis.

PubMed

Hibino, Toshihiko; Sakaguchi, Masakiyo; Miyamoto, Shoko; Yamamoto, Mami; Motoyama, Akira; Hosoi, Junichi; Shimokata, Tadashi; Ito, Tomonobu; Tsuboi, Ryoji; Huh, Nam-Ho

2013-01-01

The calcium-binding proteins S100A8 and S100A9 can dimerize to form calprotectin, the release of which during tissue damage has been implicated in inflammation and metastasis. However, receptor(s) mediating the physiologic and pathophysiologic effects of this damage-associated "danger signal" are uncertain. In this study, searching for candidate calprotectin receptors by affinity isolation-mass spectrometry, we identified the cell surface glycoprotein EMMPRIN/BASIGIN (CD147/BSG). EMMPRIN specifically bound to S100A9 but not S100A8. Induction of cytokines and matrix metalloproteases (MMP) by S100A9 was markedly downregulated in melanoma cells by attenuation of EMMPRIN. We found that EMMPRIN signaling used the TNF receptor-associated factor TRAF2 distinct from the known S100-binding signaling pathway mediated by RAGE (AGER). S100A9 strongly promoted migration when EMMPRIN was highly expressed, independent of RAGE, whereas EMMPRIN blockade suppressed migration by S100A9. Immunohistologic analysis of melanomas revealed that EMMPRIN was expressed at both the invasive edge of lesions and the adjacent epidermis, where S100A9 was also strongly expressed. In epidermal-specific transgenic mice, tail vein-injected melanoma accumulated in skin expressing S100A9 but not S100A8. Together, our results establish EMMPRIN as a receptor for S100A9 and suggest the therapeutic use in targeting S100A9-EMMPRIN interactions.

Inflammatory sensitization of nociceptors depends on activation of NMDA receptors in DRG satellite cells.

PubMed

Ferrari, Luiz Fernando; Lotufo, Celina Monteiro; Araldi, Dionéia; Rodrigues, Marcos A; Macedo, Larissa P; Ferreira, Sérgio H; Parada, Carlos Amilcar

2014-12-23

The present study evaluated the role of N-methyl-D-aspartate receptors (NMDARs) expressed in the dorsal root ganglia (DRG) in the inflammatory sensitization of peripheral nociceptor terminals to mechanical stimulation. Injection of NMDA into the fifth lumbar (L5)-DRG induced hyperalgesia in the rat hind paw with a profile similar to that of intraplantar injection of prostaglandin E2 (PGE2), which was significantly attenuated by injection of the NMDAR antagonist D(-)-2-amino-5-phosphonopentanoic acid (D-AP-5) in the L5-DRG. Moreover, blockade of DRG AMPA receptors by the antagonist 6,7-dinitroquinoxaline-2,3-dione had no effect in the PGE2-induced hyperalgesia in the paw, showing specific involvement of NMDARs in this modulatory effect and suggesting that activation of NMDAR in the DRG plays an important role in the peripheral inflammatory hyperalgesia. In following experiments we observed attenuation of PGE2-induced hyperalgesia in the paw by the knockdown of NMDAR subunits NR1, NR2B, NR2D, and NR3A with antisense-oligodeoxynucleotide treatment in the DRG. Also, in vitro experiments showed that the NMDA-induced sensitization of cultured DRG neurons depends on satellite cell activation and on those same NMDAR subunits, suggesting their importance for the PGE2-induced hyperalgesia. In addition, fluorescent calcium imaging experiments in cultures of DRG cells showed induction of calcium transients by glutamate or NMDA only in satellite cells, but not in neurons. Together, the present results suggest that the mechanical inflammatory nociceptor sensitization is dependent on glutamate release at the DRG and subsequent NMDAR activation in satellite glial cells, supporting the idea that the peripheral hyperalgesia is an event modulated by a glutamatergic system in the DRG.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boettcher, M.; Czernin, J.; Sun, K.

The {beta}{sub 1} receptor blockade reduces cardiac work and may thereby lower myocardial blood flow (MBF) at rest. The effect of {beta}{sub 1} receptor blockade on hyperemic MBF is unknown. To evaluate the effect of selective {beta}{sub 1} receptor blockade on MBF at rest and during dipyridamole induced hyperemia, 10 healthy volunteers (8 men, 2 women, mean age 24 {+-} 5 yr) were studied using {sup 13}N-ammonia PET (two-compartment model) under control conditions and again during metoprolol (50 mg orally 12 hr and 1 hr before the study). The resting rate pressure product (6628 {+-} 504 versus 5225 {+-} 807)more » and heart rate (63 {+-} 6-54 {plus_minus} 5 bpm) declined during metoprolol (p < 0.05). Similarly, heart rate and rate pressure product declined from the baseline dipyridamole study to dipyridamole plus metoprolol (p < 0.05). Resting MBF declined in proportion to cardiac work by approximately 20% from 0.61 {+-} 0.09-0.51 {+-} 0.10 ml/g/min (p < 0.05). In contrast, hyperemic MBF increased when metoprolol was added to dipyridamole (1.86 {plus_minus} 0.27 {+-} 0.45 ml/g/min; p<0.05). The decrease in resting MBF together with the increase in hyperemic MBF resulted in a significant increase in the myocardial flow reserve during metoprolol (3.14 {+-} 0.80-4.61 {+-} 0.68; p<0.01). The {beta}{sub 1} receptor blockade increases coronary vasodilatory capacity and myocardial flow reserve. However, the mechanisms accounting for this finding remain uncertain. 32 refs., 2 figs., 2 tabs.« less

Frontal D2/3 Receptor Availability in Schizophrenia Patients Before and After Their First Antipsychotic Treatment: Relation to Cognitive Functions and Psychopathology.

PubMed

Nørbak-Emig, Henrik; Ebdrup, Bjørn H; Fagerlund, Birgitte; Svarer, Claus; Rasmussen, Hans; Friberg, Lars; Allerup, Peter N; Rostrup, Egill; Pinborg, Lars H; Glenthøj, Birte Y

2016-05-01

We have previously reported associations between frontal D2/3 receptor binding potential positive symptoms and cognitive deficits in antipsychotic-naïve schizophrenia patients. Here, we examined the effect of dopamine D2/3 receptor blockade on cognition. Additionally, we explored the relation between frontal D2/3 receptor availability and treatment effect on positive symptoms. Twenty-five antipsychotic-naïve first-episode schizophrenia patients were examined with the Positive and Negative Syndrome Scale, tested with the cognitive test battery Cambridge Neuropsychological Test Automated Battery, scanned with single-photon emission computerized tomography using the dopamine D2/3 receptor ligand [(123)I]epidepride, and scanned with MRI. After 3 months of treatment with either risperidone (n=13) or zuclopenthixol (n=9), 22 patients were reexamined. Blockade of extrastriatal dopamine D2/3 receptors was correlated with decreased attentional focus (r = -0.615, P=.003) and planning time (r = -0.436, P=.048). Moreover, baseline frontal dopamine D2/3 binding potential and positive symptom reduction correlated positively (D2/3 receptor binding potential left frontal cortex rho = 0.56, P=.003; D2/3 receptor binding potential right frontal cortex rho = 0.48, P=.016). Our data support the hypothesis of a negative influence of D2/3 receptor blockade on specific cognitive functions in schizophrenia. This is highly clinically relevant given the well-established association between severity of cognitive disturbances and a poor functional outcome in schizophrenia. Additionally, the findings support associations between frontal D2/3 receptor binding potential at baseline and the effect of antipsychotic treatment on positive symptoms. © The Author 2016. Published by Oxford University Press on behalf of CINP.

Substance P receptor blockade decreases stretch-induced lung cytokines and lung injury in rats.

PubMed

Brégeon, Fabienne; Steinberg, Jean Guillaume; Andreotti, Nicolas; Sabatier, Jean-Marc; Delpierre, Stéphane; Ravailhe, Sylvie; Jammes, Yves

2010-04-15

Overdistension of lung tissue during mechanical ventilation causes cytokine release, which may be facilitated by the autonomic nervous system. We used mechanical ventilation to cause lung injury in rats, and studied how cervical section of the vagus nerve, or substance P (SP) antagonism, affected the injury. The effects of 40 or 25 cmH(2)O high airway pressure injurious ventilation (HV(40) and HV(25)) were studied and compared with low airway pressure ventilation (LV) and spontaneous breathing (controls). Lung mechanics, lung weight, gas exchange, lung myeloperoxidase activity, lung concentrations of interleukin (IL)-1 beta and IL-6, and amounts of lung SP were measured. Control rats were intact, others were bivagotomized, and in some animals we administered the neurokinin-1 (NK-1) receptor blocking agent SR140333. We first determined the durations of HV(40) and HV(25) that induced the same levels of lung injury and increased lung contents of IL-1 beta and IL-6. They were 90 min and 120 min, respectively. Both HV(40) and HV(25) increased lung SP, IL-1 beta and IL-6 levels, these effects being markedly reduced by NK-1 receptor blockade. Bivagotomy reduced to a lesser extent the HV(40)- and HV(25)-induced increases in SP but significantly reduced cytokine production. Neither vagotomy nor NK-1 receptor blockade prevented HV(40)-induced lung injury but, in the HV(25) group, they made it possible to maintain lung injury indices close to those measured in the LV group. This study suggests that both neuronal and extra-neuronal SP might be involved in ventilator-induced lung inflammation and injury. NK-1 receptor blockade could be a pharmacological tool to minimize some adverse effects of mechanical ventilation.

Effects of NMDA and non-NMDA ionotropic glutamate receptors in the medial preoptic area on body temperature in awake rats.

PubMed

Sengupta, Trina; Jaryal, Ashok Kumar; Mallick, Hruda Nanda

2016-10-01

Glutamate when microinjected at the medial preoptic area (mPOA) influences brain temperature (T br ) and body temperature (T b ) in rats. Glutamate and its various receptors are present at the mPOA. The aim of this study was to identify the contribution of each of the ionotropic glutamatergic receptors at the mPOA on changes in T br and T b in freely moving rats. Adult male Wistar rats (n=40) were implanted with bilateral guide cannula with indwelling styli above the mPOA. A telemetric transmitter was implanted at the peritoneum to record T b and locomotor activity (LMA). A precalibrated thermocouple wire implanted near the hypothalamus was used to assess T br . Specific agonist for each ionotropic glutamate receptor was microinjected into the mPOA and its effects on temperature and LMA were measured in the rats. The rats were also microinjected with the respective ionotropic receptor antagonists, 15min prior to the microinjection of each agonist. Amongst amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-d-aspartate (NMDA) and kainic acid, AMPA increased T b and LMA when injected at the mPOA. Specific antagonists for AMPA receptors was able to attenuate this increase (p<0.005). Pharmacological blockade of NMDA was able to lower T br only. Microinjection of kainic acid and its antagonist had no effect on the variables. The finding of the study suggests that activation of the AMPA receptors at the mPOA, leads to the rise in body temperature. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of activation and blockade of dopamine receptors on the extinction of a passive avoidance reaction in mice with a depressive-like state.

PubMed

Dubrovina, N I; Zinov'eva, D V

2010-01-01

Learning and extinction of a conditioned passive avoidance reaction resulting from neuropharmacological actions on dopamine D(1) and D(2) receptors were demonstrated to be specific in intact mice and in mice with a depressive-like state. Learning was degraded only after administration of the D(2) receptor antagonist sulpiride and was independent of the initial functional state of the mice. In intact mice, activation of D(2) receptors with quinpirole led to a deficit of extinction, consisting of a reduction in the ability to acquire new inhibitory learning in conditions associated with the disappearance of the expected punishment. In mice with the "behavioral despair" reaction, characterized by delayed extinction, activation of D(1) receptors with SKF38393 normalized this process, while the D(2) agonist was ineffective. A positive effect consisting of accelerated extinction of the memory of fear of the dark ("dangerous") sector of the experimental chamber was also seen on blockade of both types of dopamine receptor.

METHAMPHETAMINE-INDUCED DOPAMINE TERMINAL DEFICITS IN THE NUCLEUS ACCUMBENS ARE EXACERBATED BY REWARD-ASSOCIATED CUES AND ATTENUATED BY CB1 RECEPTOR ANTAGONISM

PubMed Central

Loewinger, Gabriel C.; Beckert, Michael V.; Tejeda, Hugo A.; Cheer, Joseph F.

2012-01-01

Methamphetamine (METH) exposure is primarily associated with deleterious effects to dopaminergic neurons. While several studies have implicated the endocannabinoid system in METH’s locomotor, rewarding and neurochemical effects, a role for this signaling system in METH’s effects on dopamine terminal dynamics has not been elucidated. Given that CB1 receptor blockade reduces the acute potentiation of phasic extracellular dopamine release from other psychomotor stimulant drugs and that the degree of acute METH-induced increases in extracellular dopamine levels is related to the severity of dopamine depletion, we predicted that pretreatment with the CB1 receptor antagonist rimonabant would reduce METH-induced alterations at dopamine terminals. Furthermore, we hypothesized that administration of METH in environments where reward associated-cues were present would potentiate METH’s acute effects on dopamine release in the nucleus accumbens and exacerbate changes in dopamine terminal activity. Fast-scan cyclic voltammetry was used to measure electrically-evoked dopamine release in the nucleus accumbens and revealed markers of compromised dopamine terminal integrity nine days after a single dose of METH. These were exacerbated in animals that received METH in the presence of reward-associated cues, and attenuated in rimonabant-pretreated animals. While these deficits in dopamine dynamics were associated with reduced operant responding on days following METH administration in animals treated with only METH, rimonabant-pretreated animals exhibited levels of operant responding comparable to control. Moreover, dopamine release correlated significantly with changes in lever pressing behavior that occurred on days following METH administration. Together these data suggest that the endocannabinoid system is involved in the subsecond dopaminergic response to METH. PMID:22306525

Blockade of Central Angiotensin II AT1 Receptor Protects the Brain from Ischemia/Reperfusion Injury in Normotensive Rats.

PubMed

Panahpour, Hamdolah; Nekooeian, Ali Akbar; Dehghani, Gholam Abbas

2014-11-01

Stroke is the third leading cause of invalidism and death in industrialized countries. There are conflicting reports about the effects of Angiotensin II on ischemia-reperfusion brain injuries and most data have come from chronic hypertensive rats. In this study, hypotensive and non-hypotensive doses of candesartan were used to investigate the effects of angiotensin II AT1 receptor blockade by transient focal cerebral ischemia in normotensive rats. In this experimental study, 48 male Sprague-Dawley rats were randomly divided into four groups (n=12). Sham group, the control ischemic group, and two ischemic groups received candesartan at doses of 0.1 or 0.5 mg/kg at one hour before ischemia. Transient focal cerebral ischemia was induced by 60 minutes occlusion of the middle cerebral artery, followed by 24 h reperfusion. The neurological deficit score was evaluated at the end of the reperfusion period. The total cortical and striatal infarct volumes were determined using triphenyltetrazolium chloride staining technique. Tissue swelling was calculated for the investigation of ischemic brain edema formation. In comparison with the control ischemic group, AT1 receptor blockade with both doses of candesartan (0.1 or 0.5 mg/kg) significantly improved neurological deficit and lowered cortical and striatal infarct sizes. In addition, pretreatment with candesartan significantly reduced ischemia induced tissue swelling. Angiotensin II by stimulating AT1 receptors, participates in ischemia-reperfusion injuries and edema formation. AT1 receptor blockade with candesartan decreased ischemic brain injury and edema and improved neurological outcome.

Blockade of Central Angiotensin II AT1 Receptor Protects the Brain from Ischemia/Reperfusion Injury in Normotensive Rats

PubMed Central

Panahpour, Hamdolah; Nekooeian, Ali Akbar; Dehghani, Gholam Abbas

2014-01-01

Background: Stroke is the third leading cause of invalidism and death in industrialized countries. There are conflicting reports about the effects of Angiotensin II on ischemia-reperfusion brain injuries and most data have come from chronic hypertensive rats. In this study, hypotensive and non-hypotensive doses of candesartan were used to investigate the effects of angiotensin II AT1 receptor blockade by transient focal cerebral ischemia in normotensive rats. Methods: In this experimental study, 48 male Sprague-Dawley rats were randomly divided into four groups (n=12). Sham group, the control ischemic group, and two ischemic groups received candesartan at doses of 0.1 or 0.5 mg/kg at one hour before ischemia. Transient focal cerebral ischemia was induced by 60 minutes occlusion of the middle cerebral artery, followed by 24 h reperfusion. The neurological deficit score was evaluated at the end of the reperfusion period. The total cortical and striatal infarct volumes were determined using triphenyltetrazolium chloride staining technique. Tissue swelling was calculated for the investigation of ischemic brain edema formation. Results: In comparison with the control ischemic group, AT1 receptor blockade with both doses of candesartan (0.1 or 0.5 mg/kg) significantly improved neurological deficit and lowered cortical and striatal infarct sizes. In addition, pretreatment with candesartan significantly reduced ischemia induced tissue swelling. Conclusion: Angiotensin II by stimulating AT1 receptors, participates in ischemia-reperfusion injuries and edema formation. AT1 receptor blockade with candesartan decreased ischemic brain injury and edema and improved neurological outcome. PMID:25429176

Deterioration of kidney function by the (pro)renin receptor blocker handle region peptide in aliskiren-treated diabetic transgenic (mRen2)27 rats.

PubMed

te Riet, Luuk; van den Heuvel, Mieke; Peutz-Kootstra, Carine J; van Esch, Joep H M; van Veghel, Richard; Garrelds, Ingrid M; Musterd-Bhaggoe, Usha; Bouhuizen, Angelique M; Leijten, Frank P J; Danser, A H Jan; Batenburg, Wendy W

2014-05-15

Dual renin-angiotensin system (RAS) blockade in diabetic nephropathy is no longer feasible because of the profit/side effect imbalance. (Pro)renin receptor [(P)RR] blockade with handle region peptide (HRP) has been reported to exert beneficial effects in various diabetic models in a RAS-independent manner. To what degree (P)RR blockade adds benefits on top of RAS blockade is still unknown. In the present study, we treated diabetic TGR(mREN2)27 rats, a well-established nephropathy model with high prorenin levels [allowing continuous (P)RR stimulation in vivo], with HRP on top of renin inhibition with aliskiren. Aliskiren alone lowered blood pressure and exerted renoprotective effects, as evidenced by reduced glomerulosclerosis, diuresis, proteinuria, albuminuria, and urinary aldosterone levels as well as diminished renal (P)RR and ANG II type 1 receptor expression. It also suppressed plasma and tissue RAS activity and suppressed cardiac atrial natriuretic peptide and brain natriuretic peptide expression. HRP, when given on top of aliskiren, did not alter the effects of renin inhibition on blood pressure, RAS activity, or aldosterone. However, it counteracted the beneficial effects of aliskiren in the kidney, induced hyperkalemia, and increased plasma plasminogen activator-inhibitor 1, renal cyclooxygenase-2, and cardiac collagen content. All these effects have been linked to (P)RR stimulation, suggesting that HRP might, in fact, act as a partial agonist. Therefore, the use of HRP on top of RAS blockade in diabetic nephropathy is not advisable. Copyright © 2014 the American Physiological Society.

Substance P-induced respiratory excitation is blunted by delta-receptor specific opioids in the rat medulla oblongata.

PubMed

Chen, Z; Hedner, J; Hedner, T

1996-06-01

The effects of substance P (SP) and the naturally occurring met-enkephalin and the synthetic mu-specific opioid agonist, DAGO (Tyr-D-Ala-Gly-N-Methy-Phe-Gly-ol) and the delta-specific opioid agonist DADL (Tyr-D-Ala-Gly-Phe-D-Leu) on basal ventilation were investigated in halothane-anaesthetized rats. Local injections of SP (0.75-1.5 nmol) in the ventrolateral medulla oblongata (VLM), e.g. nucleus paragigantocellularis, and nucleus reticularis lateralis increased ventilation because of an elevation of tidal volume. Met-enkephalin induced a short-lasting ventilatory depression mainly because of a depression of tidal volume. Activation of delta- and mu-opioid receptors in the VLM by local application of DADL and DAGO, respectively, induced ventilatory depression, which was later in onset and more long-lasting. Local administration of met-enkephalin into the VLM also produced a long-lasting inhibition of the SP-induced ventilatory excitation. A similar blockade of the SP-induced excitatory ventilatory response could be elicited by DADL but not by DAGO. This antagonistic effect was attenuated by local application of the delta-opioid receptor antagonist ICI 154. 129. We conclude that the naturally occurring met-enkephalin as well as synthetic mu- and delta-specific enkephalin analogues (DAGO and DADL, respectively) in VLM depress basal ventilation by an effect on inspiratory drive. There is a functional antagonism between activation of delta-opioid receptors and SP receptors into the VLM in respect to respiratory regulation.

Cholinergic dependence of taste memory formation: evidence of two distinct processes.

PubMed

Gutiérrez, Ranier; Rodriguez-Ortiz, Carlos J; De La Cruz, Vanesa; Núñez-Jaramillo, Luis; Bermudez-Rattoni, Federico

2003-11-01

Learning the aversive or positive consequences associated with novel taste solutions has a strong significance for an animal's survival. A lack of recognition of a taste's consequences could prevent ingestion of potential edibles or encounter death. We used conditioned taste aversion (CTA) and attenuation of neophobia (AN) to study aversive and safe taste memory formation. To determine if muscarinic receptors in the insular cortex participate differentially in both tasks, we infused the muscarinic antagonists scopolamine at distinct times before or after the presentation of a strong concentration of saccharin, followed by either an i.p. injection of a malaise-inducing agent or no injection. Our results showed that blockade of muscarinic receptors before taste presentation disrupts both learning tasks. However, the same treatment after the taste prevents AN but not CTA. These results clearly demonstrate that cortical cholinergic activity participates in the acquisition of both safe and aversive memory formation, and that cortical muscarinic receptors seem to be necessary for safe but not for aversive taste memory consolidation. These results suggest that the taste memory trace is processed in the insular cortex simultaneously by at least two independent mechanisms, and that their interaction would determine the degree of aversion or preference learned to a novel taste.

Effect of a positive reinforcing stimulus on fear memory reconsolidation in ethanol withdrawn rats: Influence of d-cycloserine.

PubMed

Ortiz, Vanesa; Molina, Víctor Alejandro; Martijena, Irene Delia

2016-12-15

The pharmacological blockade of memory reconsolidation has been suggested as a potential treatment to the attenuation of maladaptive memories associated to psychiatric disorders and drug addiction. To interfere with the process of fear memory reconsolidation using a manipulation safer than pharmacological interventions, here we examined whether a positive reinforcing stimulus (non-alcoholic beer, NB) post-memory retrieval can decrease the fear response in ethanol withdrawn (ETOH) animals. We first evaluated the potential interfering effect of NB on memory reconsolidation in non-ethanol dependent (control, CON) rats. Non-alcoholic beer intake shortly after memory retrieval attenuated the fear response in CON rats. A resistance to destabilization/reconsolidation process was previously observed in ETOH rats, which was reversed by the activation of NMDA receptor induced by pre-retrieval d-cycloserine (DCS) administration. Therefore, the influence of DCS (5mg/kg; i.p.) to facilitate the disruptive effect of NB on fear memory was examined in ETOH animals. As expected, NB was ineffective to attenuate the fear response in ETOH rats, with DCS being necessary to promote the disruptive effect of NB on the reconsolidation in these animals. Hence, DCS/reinforcing stimulus in combination with memory reactivation can be considered as an alternative approach for disrupting resistant fear memories. Copyright © 2016 Elsevier B.V. All rights reserved.

Androgen receptor (AR) suppresses miRNA-145 to promote renal cell carcinoma (RCC) progression independent of VHL status

PubMed Central

Chen, Yuan; Sun, Yin; Rao, Qun; Xu, Hua; Li, Lei; Chang, Chawnshang

2015-01-01

Mutational inactivation of the VHL tumor suppressor plays key roles in the development of renal cell carcinoma (RCC), and mutated VHL-mediated VEGF induction has become the main target for the current RCC therapy. Here we identified a signal pathway of VEGF induction by androgen receptor (AR)/miRNA-145 as a new target to suppress RCC progression. Mechanism dissection revealed that AR might function through binding to the androgen receptor element (ARE) located on the promoter region of miRNA-145 to suppress p53's ability to induce expression of miRNA-145 that normally suppresses expression of HIF2α/VEGF/MMP9/CCND1. Suppressing AR with AR-shRNA or introducing exogenous miRNA-145 mimic can attenuate RCC progression independent of VHL status. MiR-145 mimic in preclinical RCC orthotopic xenograft mouse model revealed its efficacy in suppression of RCC progression. These results together identified signals by AR-suppressed miRNA-145 as a key player in the RCC progression via regulating HIF2α/VEGF/MMP9/CCND1 expression levels. Blockade of the newly identified signal by AR inhibition or miRNA-145 mimics has promising therapeutic benefit to suppress RCC progression. PMID:26304926

Ventrolateral orbital cortex oxytocin attenuates neuropathic pain through periaqueductal gray opioid receptor.

PubMed

Taati, Mina; Tamaddonfard, Esmaeal

2018-06-01

Oxytocin plays an important role in supraspinal modulation of pain. In the present study, we investigated the effects of ventrolateral orbital cortex (VLOC) microinjection of oxytocin on neuropathic pain after blockade of opioid receptors in this area and ventrolateral periaqueductal gray (vlPAG). Neuropathic pain was induced by complete transcection of preoneal and tibial branches of sciatic nerve. The VLOC and vlPAG were unilaterally (contralateral to the sciatic nerve-injured side) and bilaterally implanted with guide cannulas, respectively. Mechanical paw withdrawal threshold (PWT) was measured using von Frey filaments. Area under curve (AUC) was also calculated. Microinjection of oxytocin (5, 10 and 20 ng/site) into the VLOC increased PWT. Antiallodynia induced by oxytocin (20 ng/site) was inhibited by prior intra-VLOC administration of atosiban (an oxytocin receptor antagonist, 100 ng/site) and naloxone (an opioid receptor antagonist, 500 ng/site). Prior microinjection of naloxone (500 ng/site) into the vlPAG also inhibited antiallodynia induced by intra-VLOC microinjection of oxytocin (20 ng/site). All the VLOC and vlPAG microinjected drugs did not alter locomotor activity. It is concluded that oxytocin and its receptor may be involved in modulation of neuropathic pain at the VLOC level. Opioid receptors of VLOC and vlPAG might be involved in the antiallodynic effect of the VLOC-microinjected oxytocin. Copyright © 2017 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Neonatal NMDA receptor blockade alters anxiety- and depression-related behaviors in a sex-dependent manner in mice.

PubMed

Amani, Mohammad; Samadi, Hanieh; Doosti, Mohammad-Hossein; Azarfarin, Maryam; Bakhtiari, Amir; Majidi-Zolbanin, Naime; Mirza-Rahimi, Mehrdad; Salari, Ali-Akbar

2013-10-01

There is increasing evidence that N-methyl-D-aspartate (NMDA) receptor blockade in the neonatal period has a long-lasting influence on brain and behavior development and has been linked to an increased risk for neuropsychiatric disorders in later life. We sought to determine whether postnatal NMDA receptor blockade can affect normal development of body weight, corticosterone levels, anxiety- and depression-related behaviors in male and female mice in adulthood. For this purpose, male and female NMRI mice were treated with either saline or phencyclidine (PCP; 5 and 10 mg/kg, s.c.) on postnatal days (PND) 7, 9, and 11, and then subjected to different behavioral tests, including open field, elevated plus-maze, elevated zero-maze, light-dark box, tail suspension test and forced swimming test in adulthood. The results indicated that neonatal PCP treatment reduced body weight during neonatal and adulthood periods, and did not alter baseline corticosterone levels in both male and female mice. Moreover, this study obtained some experimental evidence showing the PCP at dose of 10 mg/kg increases stress-induced corticosterone levels, anxiety- and depression-related behaviors in males, while decreasing levels of anxiety without any significant effect on depression in female mice in adulthood. These data support the argument that neonatal NMDA receptor blockade can lead to behavioral abnormalities and psychiatric diseases in adulthood. Collectively, our findings suggest that neonatal exposure to PCP may have profound effects on the development of anxiety- and depression-related behaviors in a sex- and dose-dependent manner in mice. Copyright © 2013 Elsevier Ltd. All rights reserved.

Dilation of epicardial coronary arteries by the G protein-coupled estrogen receptor agonists G-1 and ICI 182,780.

PubMed

Meyer, Matthias R; Baretella, Oliver; Prossnitz, Eric R; Barton, Matthias

2010-01-01

Endogenous estrogens protect from coronary artery disease in premenopausal women, but the mechanisms involved are only partly understood. This study investigated whether activation of the novel G protein-coupled estrogen receptor (GPER, formerly known as GPR30) affects coronary artery tone, and whether this is affected by concomitant blockade of estrogen receptors (ER) alpha and beta. Rings of epicardial porcine coronary arteries suspended in organ chambers were precontracted with prostaglandin F(2)alpha, and direct effects of G-1 (GPER agonist) and ICI 182,780 (GPER agonist and ERalpha/ERbeta antagonist) were determined. In addition, indirect effects on contractility to endothelin-1 and serotonin (a vasoconstrictor released from aggregating platelets during acute myocardial infarction) were assessed. ICI 182,780 and G-1 caused acute dilation of coronary arteries to a comparable degree (p < 0.05 vs. solvent control). Both GPER agonists attenuated contractions to endothelin-1 (p < 0.05 vs. ethanol), but not to serotonin (n.s.). In summary, these findings provide evidence for direct and indirect coronary artery dilator effects of GPER independent of ERalpha and ERbeta, and are the first demonstration of arterial vasodilation in response to ICI 182,780. Copyright 2010 S. Karger AG, Basel.

Local GABA receptor blockade reveals hindlimb responses in the SI forelimb-stump representation of neonatally amputated rats.

PubMed

Pluto, Charles P; Lane, Richard D; Rhoades, Robert W

2004-07-01

In adult rats that sustained forelimb amputation on the day of birth, there are numerous multi-unit recording sites in the forelimb-stump representation of primary somatosensory cortex (SI) that also respond to cutaneous stimulation of the hindlimb when cortical receptors for GABA are blocked. These normally suppressed hindlimb inputs originate in the SI hindlimb representation and synapse in the dysgranular cortex before exciting SI forelimb-stump neurons. In our previous studies, GABA (A + B) receptor blockade was achieved by topically applying a bicuculline methiodide/saclofen solution (BMI/SAC) to the cortical surface. This treatment blocks receptors throughout SI and does not allow determination of where along the above circuit the GABA-mediated suppression of hindlimb information occurs. In this study, focal injections of BMI/SAC were delivered to three distinct cortical regions that are involved in the hindlimb-to-forelimb-stump pathway. Blocking GABA receptors in the SI hindlimb representation and in the dysgranular cortex was largely ineffective in revealing hindlimb inputs ( approximately 10% of hindlimb inputs were revealed in both cases). In contrast, when the blockade was targeted at forelimb-stump recording sites, >80% of hindlimb inputs were revealed. Thus GABAergic interneurons within the forelimb-stump representation suppress the expression of reorganized hindlimb inputs to the region. A circuit model incorporating these and previous observations is presented and discussed.

Intra-articular administration of an antibody against CSF-1 receptor reduces pain-related behaviors and inflammation in CFA-induced knee arthritis.

PubMed

Alvarado-Vazquez, P A; Morado-Urbina, C E; Castañeda-Corral, G; Acosta-Gonzalez, R I; Kitaura, H; Kimura, K; Takano-Yamamoto, T; Jiménez-Andrade, J M

2015-01-01

Several studies have shown that blockade of colony stimulating factor-1 (CSF-1) or its receptor (CSF-1R) inhibits disease progression in rodent models of rheumatoid arthritis (RA); however, the role of the CSF-1/CSF-1R pathway in RA-induced pain and functional deficits has not been studied. Thus, we examined the effect of chronic intra-articular administration of a monoclonal anti-CSF-1R antibody (AFS98) on spontaneous pain, knee edema and functional disabilities in mice with arthritis. Unilateral arthritis was produced by multiple injections of complete Freund's adjuvant (CFA) into the right knee joint of adult male ICR mice. CFA-injected mice were then treated twice weekly from day 10 until day 25 with anti-CSF-1R antibody (3 and 10 μg/5 μL per joint), isotype control (rat IgG 10 μg/5 μL per joint) or PBS (5 μl/joint). Knee edema, spontaneous flinching, vertical rearing and horizontal exploratory activity were assessed at different days. Additionally, counts of peripheral leukocytes and body weight were measured to evaluate general health status. Intra-articular treatment with anti-CSF-1R antibody significantly increased horizontal exploratory activity and vertical rearing as well as reduced spontaneous flinching behavior and knee edema as compared to CFA-induced arthritis mice treated with PBS. Treatment with this antibody neither significantly affect mouse body weight nor the number of peripheral leukocytes. These results suggest that blockade of CSF-1R at the initial injury site (joint) could represent a therapeutic alternative for improving the functional disabilities and attenuating pain and inflammation in patients with RA. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

The CRF1 Antagonist Verucerfont in Anxious Alcohol-Dependent Women: Translation of Neuroendocrine, But not of Anti-Craving Effects

PubMed Central

Schwandt, Melanie L; Cortes, Carlos R; Kwako, Laura E; George, David T; Momenan, Reza; Sinha, Rajita; Grigoriadis, Dimitri E; Pich, Emilio Merlo; Leggio, Lorenzo; Heilig, Markus

2016-01-01

Blockade of corticotropin-releasing factor receptor 1 (CRF1) suppresses stress-induced alcohol seeking in rodents, but clinical translation remains. Here, we first showed that the CRF1 antagonist verucerfont potently blocks hypothalamic-pituitary adrenal (HPA) axis activation in adrenalectomized rats. We then evaluated verucerfont for its ability to block HPA axis activation and reduce stress-induced alcohol craving in alcohol-dependent patients. Anxious, alcohol-dependent women (age 21–65 years, n=39) were admitted to the NIH Clinical Center and completed withdrawal treatment before enrollment if needed. One-week single-blind placebo was followed by randomized double-blind verucerfont (350 mg per day) or placebo for 3 weeks. Verucerfont effects on the HPA axis were evaluated using the dexamethasone-CRF test. Craving was evaluated using two established protocols, one that combines a social stressor with physical alcohol cue exposure, and one that uses guided imagery to present personalized stress, alcohol, or neutral stimuli. An fMRI session examined brain responses to negative affective stimuli and alcohol cues. In contrast to our recent observations with another CRF1 antagonist, pexacerfont, verucerfont potently blocked the HPA axis response to the dexamethasone-CRF test, but left alcohol craving unaffected. Right amygdala responses to negative affective stimuli were significantly attenuated by verucerfont, but responses to alcohol-associated stimuli were increased in some brain regions, including left insula. Discontinuation rates were significantly higher in the verucerfont group. Our findings provide the first translational evidence that CRF1 antagonists with slow receptor dissociation kinetics may have increased efficacy to dampen HPA axis responses. The findings do not support a clinical efficacy of CRF1 blockade in stress-induced alcohol craving and relapse. PMID:27109623

PTH modulation of NCC activity regulates TRPV5 Ca2+ reabsorption.

PubMed

Hoover, Robert S; Tomilin, Viktor; Hanson, Lauren; Pochynyuk, Oleh; Ko, Benjamin

2016-01-15

Since parathyroid hormone (PTH) is known to increase transient receptor potential vanilloid (TRPV)5 activity and decrease Na(+)-Cl(-) cotransporter (NCC) activity, we hypothesized that decreased NCC-mediated Na(+) reabsorption contributes to the enhanced TRPV5 Ca(2+) reabsorption seen with PTH. To test this, we used mDCT15 cells expressing functional TRPV5 and ruthenium red-sensitive (45)Ca(2+) uptake. PTH increased (45)Ca(2+) uptake to 8.8 ± 0.7 nmol·mg(-1)·min(-1) (n = 4, P < 0.01) and decreased NCC activity from 75.4 ± 2.7 to 20.3 ± 1.3 nmol·mg(-1)·min(-1) (n = 4, P < 0.01). Knockdown of Ras guanyl-releasing protein (RasGRP)1 had no baseline effect on (45)Ca(2+) uptake but significantly attenuated the response to PTH from a 45% increase (6.0 ± 0.2 to 8.7 ± 0.4 nmol·mg(-1)·min(-1)) in control cells to only 20% in knockdown cells (6.1 ± 0.1 to 7.3 ± 0.2 nmol·mg(-1)·min(-1), n = 4, P < 0.01). Inhibition of PKC and PKA resulted in further attenuation of the PTH effect. RasGRP1 knockdown decreased the magnitude of the TRPV5 response to PTH (7.9 ± 0.1 nmol·mg(-1)·min(-1) for knockdown compared with 9.1 ± 0.1 nmol·mg(-1)·min(-1) in control), and the addition of thiazide eliminated this effect (a nearly identical 9.0 ± 0.1 nmol·mg(-1)·min(-1)). This indicates that functionally active NCC is required for RasGRP1 knockdown to impact the PTH effect on TRPV5 activity. Knockdown of with no lysine kinase (WNK)4 resulted in an attenuation of the increase in PTH-mediated TRPV5 activity. TRPV5 activity increased by 36% compared with 45% in control (n = 4, P < 0.01 between PTH-treated groups). PKC blockade further attenuated the PTH effect, whereas combined PKC and PKA blockade in WNK4KD cells abolished the effect. We conclude that modulation of NCC activity contributes to the response to PTH, implying a role for hormonal modulation of NCC activity in distal Ca(2+) handling.

Inhibition of β2-adrenergic receptor reduces triple-negative breast cancer brain metastases: The potential benefit of perioperative β-blockade.

PubMed

Choy, Cecilia; Raytis, John L; Smith, David D; Duenas, Matthew; Neman, Josh; Jandial, Rahul; Lew, Michael W

2016-06-01

In response to recent studies, we investigated an association between perioperative β-blockade and breast cancer metastases. First, a retrospective study examining perioperative β-blocker use and cancer recurrence and metastases was conducted on 1,029 patients who underwent breast cancer surgery at the City of Hope Cancer Center between 2000 and 2010. We followed the clinical study and examined proliferation, migration, and invasion in vitro of primary and brain-metastatic breast cancer cells in response to β2-activation and inhibition. We also investigated in vivo the metastatic potential of propranolol-treated metastatic cells. For stage II breast cancer patients, perioperative β-blockade was associated with decreased cancer recurrence using Cox regression analysis (hazard's ratio =0.51; 95% CI: 0.23-0.97; p=0.041). Triple-negative (TN) brain-metastatic cells were found to have increased β2-adrenergic receptor mRNA and protein expression relative to TN primary cells. In response to β2-adrenergic receptor activation, TN brain-metastatic cells also exhibited increased cell proliferation and migration relative to the control. These effects were abrogated by propranolol. Propranolol decreased β2-adrenergic receptor-activated invasion. In vivo, propranolol treatment of TN brain-metastatic cells decreased establishment of brain metastases. Our results suggest that stress and corresponding β2-activation may promote the establishment of brain metastases of TN breast cancer cells. In addition, our data suggest a benefit to perioperative β-blockade during surgery-induced stress with respect to breast cancer recurrence and metastases.

Inhibition of β2-adrenergic receptor reduces triple-negative breast cancer brain metastases: The potential benefit of perioperative β-blockade

PubMed Central

CHOY, CECILIA; RAYTIS, JOHN L.; SMITH, DAVID D.; DUENAS, MATTHEW; NEMAN, JOSH; JANDIAL, RAHUL; LEW, MICHAEL W.

2016-01-01

In response to recent studies, we investigated an association between perioperative β-blockade and breast cancer metastases. First, a retrospective study examining perioperative β-blocker use and cancer recurrence and metastases was conducted on 1,029 patients who underwent breast cancer surgery at the City of Hope Cancer Center between 2000 and 2010. We followed the clinical study and examined proliferation, migration, and invasion in vitro of primary and brain-metastatic breast cancer cells in response to β2-activation and inhibition. We also investigated in vivo the metastatic potential of propranolol-treated metastatic cells. For stage II breast cancer patients, perioperative β-blockade was associated with decreased cancer recurrence using Cox regression analysis (hazard's ratio =0.51; 95% CI: 0.23–0.97; p=0.041). Triple-negative (TN) brain-metastatic cells were found to have increased β2-adrenergic receptor mRNA and protein expression relative to TN primary cells. In response to β2-adrenergic receptor activation, TN brain-metastatic cells also exhibited increased cell proliferation and migration relative to the control. These effects were abrogated by propranolol. Propranolol decreased β2-adrenergic receptor-activated invasion. In vivo, propranolol treatment of TN brain-metastatic cells decreased establishment of brain metastases. Our results suggest that stress and corresponding β2-activation may promote the establishment of brain metastases of TN breast cancer cells. In addition, our data suggest a benefit to perioperative β-blockade during surgery-induced stress with respect to breast cancer recurrence and metastases. PMID:27035124

Long-term systemic angiotensin II type 1 receptor blockade regulates mRNA expression of dorsomedial medulla renin-angiotensin system components.

PubMed

Gilliam-Davis, Shea; Gallagher, Patricia E; Payne, Valerie S; Kasper, Sherry O; Tommasi, Ellen N; Westwood, Brian M; Robbins, Michael E; Chappell, Mark C; Diz, Debra I

2011-07-14

In Fischer 344 (F344) rats, renin-angiotensin system (RAS) blockade for 1 yr with the angiotensin II type 1 (AT(1)) receptor blocker L-158,809 prevents age-related impairments in metabolic function, similar to transgenic rats with low glial angiotensinogen (Aogen). Brain RAS regulation may contribute to the benefits of long-term systemic AT(1) antagonism. We assessed the mRNA of RAS components in the dorsomedial medulla of F344 rats at 3 (young; n = 8) or 15 mo of age (old; n = 7) and in rats treated from 3 to 15 mo of age with 20 mg/l of the AT(1) receptor antagonist L-158,809 (Old+L; n = 6). Aogen and renin mRNA were lower in the young compared with old group. Angiotensin-converting enzyme (ACE) mRNA was lower in the old and Old+L compared with the young group. ACE2 and neprilysin expression were significantly higher in Old+L compared with young or old rats. AT(1b), AT(2), and Mas receptor mRNA were higher with treatment. Leptin receptor mRNA was lower in the old rats and this was prevented by L-158,809 treatment. Dual-specificity phosphatase 1 (DUSP1) mRNA was highest in the Old+L group. Aggregate correlate summation revealed a positive relationship for Mas receptor mRNA with food intake. The findings provide evidence for regulation of dorsomedial medullary renin and Aogen mRNA during aging. Long-term AT(1) receptor blockade increases the mRNA of the enzymes ACE2 and neprilysin and the MAS receptor, which could potentially shift the balance from ANG II to ANG-(1-7) and prevent age-related declines in the leptin receptor and its signaling pathway.

Review article: clinical implications of enteric and central D2 receptor blockade by antidopaminergic gastrointestinal prokinetics.

PubMed

Tonini, M; Cipollina, L; Poluzzi, E; Crema, F; Corazza, G R; De Ponti, F

2004-02-15

Antidopaminergic gastrointestinal prokinetics (bromopride, clebopride, domperidone, levosulpiride and metoclopramide) have been exploited clinically for the management of motor disorders of the upper gastrointestinal tract, including functional dyspepsia, gastric stasis of various origins and emesis. The prokinetic effect of these drugs is mediated through the blockade of enteric (neuronal and muscular) inhibitory D2 receptors. The pharmacological profiles of the marketed compounds differ in terms of their molecular structure, affinity at D2 receptors, ability to interact with other receptor systems [5-hydroxytryptamine-3 (5-HT3) and 5-HT4 receptors for metoclopramide; 5-HT4 receptors for levosulpiride) and ability to permeate the blood-brain barrier (compared with the other compounds, domperidone does not easily cross the barrier). It has been suggested that the serotonergic (5-HT4) component of some antidopaminergic prokinetics may enhance their therapeutic efficacy in gastrointestinal disorders, such as functional dyspepsia and diabetic gastroparesis. The antagonism of central D2 receptors may lead to both therapeutic (e.g. anti-emetic effect due to D2 receptor blockade in the area postrema) and adverse (including hyperprolactinaemia and extrapyramidal dystonic reactions) effects. As the pituitary (as well as the area postrema) is outside the blood-brain barrier, hyperprolactinaemia is a side-effect occurring with all antidopaminergic prokinetics, although to different extents. Extrapyramidal reactions are most commonly observed with compounds crossing the blood-brain barrier, although with some differences amongst the various agents. Prokinetics with a high dissociation constant compared with that of dopamine at the D2 receptor (i.e. compounds that bind loosely to D2 receptors in the nigrostriatal pathway) elicit fewer extrapyramidal signs and symptoms. A knowledge of central and peripheral D2 receptor pharmacology can help the clinician to choose between the antidopaminergic prokinetics to obtain a more favourable risk/benefit ratio.

Involvement of neuropeptide FF receptors in neuroadaptive responses to acute and chronic opiate treatments

PubMed Central

Elhabazi, K; Trigo, JM; Mollereau, C; Moulédous, L; Zajac, J-M; Bihel, F; Schmitt, M; Bourguignon, JJ; Meziane, H; Petit-demoulière, B; Bockel, F; Maldonado, R; Simonin, F

2012-01-01

BACKGROUND AND PURPOSE Opiates remain the most effective compounds for alleviating severe pain across a wide range of conditions. However, their use is associated with significant side effects. Neuropeptide FF (NPFF) receptors have been implicated in several opiate-induced neuroadaptive changes including the development of tolerance. In this study, we investigated the consequences of NPFF receptor blockade on acute and chronic stimulation of opioid receptors in mice by using RF9, a potent and selective antagonist of NPFF receptors that can be administered systemically. EXPERIMENTAL APPROACH The effects of RF9 were investigated on opioid pharmacological responses including locomotor activity, antinociception, opioid-induced hyperalgesia, rewarding properties and physical dependence. KEY RESULTS RF9 had no effect on morphine-induced horizontal hyperlocomotion and slightly attenuated the decrease induced in vertical activity. Furthermore, RF9 dose-dependently blocked the long-lasting hyperalgesia produced by either acute fentanyl or chronic morphine administration. RF9 also potentiated opiate early analgesic effects and prevented the development of morphine tolerance. Finally, RF9 increased morphine-induced conditioned place preference without producing any rewarding effect by itself and decreased naltrexone-precipitated withdrawal syndrome following chronic morphine treatment. CONCLUSION AND IMPLICATIONS The NPFF system is involved in the development of two major undesirable effects: tolerance and dependence, which are clinically associated with prolonged exposure to opiates. Our findings suggest that NPFF receptors are interesting therapeutic targets to improve the analgesic efficacy of opiates by limiting the development of tolerance, and for the treatment of opioid dependence. PMID:21718302

Involvement of neuropeptide FF receptors in neuroadaptive responses to acute and chronic opiate treatments.

PubMed

Elhabazi, K; Trigo, J M; Mollereau, C; Moulédous, L; Zajac, J-M; Bihel, F; Schmitt, M; Bourguignon, J J; Meziane, H; Petit-demoulière, B; Bockel, F; Maldonado, R; Simonin, F

2012-01-01

BACKGROUND AND PURPOSE Opiates remain the most effective compounds for alleviating severe pain across a wide range of conditions. However, their use is associated with significant side effects. Neuropeptide FF (NPFF) receptors have been implicated in several opiate-induced neuroadaptive changes including the development of tolerance. In this study, we investigated the consequences of NPFF receptor blockade on acute and chronic stimulation of opioid receptors in mice by using RF9, a potent and selective antagonist of NPFF receptors that can be administered systemically. EXPERIMENTAL APPROACH The effects of RF9 were investigated on opioid pharmacological responses including locomotor activity, antinociception, opioid-induced hyperalgesia, rewarding properties and physical dependence. KEY RESULTS RF9 had no effect on morphine-induced horizontal hyperlocomotion and slightly attenuated the decrease induced in vertical activity. Furthermore, RF9 dose-dependently blocked the long-lasting hyperalgesia produced by either acute fentanyl or chronic morphine administration. RF9 also potentiated opiate early analgesic effects and prevented the development of morphine tolerance. Finally, RF9 increased morphine-induced conditioned place preference without producing any rewarding effect by itself and decreased naltrexone-precipitated withdrawal syndrome following chronic morphine treatment. CONCLUSION AND IMPLICATIONS The NPFF system is involved in the development of two major undesirable effects: tolerance and dependence, which are clinically associated with prolonged exposure to opiates. Our findings suggest that NPFF receptors are interesting therapeutic targets to improve the analgesic efficacy of opiates by limiting the development of tolerance, and for the treatment of opioid dependence. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

Ablation of type I hypersensitivity in experimental allergic conjunctivitis by eotaxin-1/CCR3 blockade

PubMed Central

Nakamura, Takao; Ohbayashi, Masaharu; Kuo, Chuan Hui; Komatsu, Naoki; Yakura, Keiko; Tominaga, Takeshi; Inoue, Yoshitsugu; Higashi, Hidemitsu; Murata, Meguru; Takeda, Shuzo; Fukushima, Atsuki; Liu, Fu-Tong; Rothenberg, Marc E.; Ono, Santa Jeremy

2009-01-01

The immune response is regulated, in part, by effector cells whose activation requires multiple signals. For example, T cells require signals emanating from the T cell antigen receptor and co-stimulatory molecules for full activation. Here, we present evidence indicating that IgE-mediated hypersensitivity reactions in vivo also require cognate signals to activate mast cells. Immediate hypersensitivity reactions in the conjunctiva are ablated in mice deficient in eotaxin-1, despite normal numbers of tissue mast cells and levels of IgE. To further define the co-stimulatory signals mediated by chemokine receptor 3 (CCR3), an eotaxin-1 receptor, effects of CCR3 blockade were tested with an allergic conjunctivitis model and in ex vivo isolated connective tissue-type mast cells. Our results show that CCR3 blockade significantly suppresses allergen-mediated hypersensitivity reactions as well as IgE-mediated mast cell degranulation. We propose that a co-stimulatory axis by CCR3, mainly stimulated by eotaxin-1, is pivotal in mast cell-mediated hypersensitivity reactions. PMID:19147836

The exhausted CD4+CXCR5+ T cells involve the pathogenesis of human tuberculosis disease.

PubMed

Bosco, Munyemana Jean; Wei, Ming; Hou, Hongyan; Yu, Jing; Lin, Qun; Luo, Ying; Sun, Ziyong; Wang, Feng

2018-06-21

The CD4 + CXCR5 + T cells have been previously established. However, their decreased frequency during tuberculosis (TB) disease is partially understood. The aim of this study was to explore the depletion of CD4 + CXCR5 + T cells in human TB. The frequency and function of CD4 + CXCR5 + T cells were evaluated in active TB (ATB) patients and healthy control (HC) individuals. The function of CD4 + CXCR5 + T cells was determined after blockade of inhibitory receptors. The frequency of CD4 + CXCR5 + T cells was decreased in ATB patients. The expression of activation markers (HLA-DR and ICOS) and inhibitory receptors (Tim-3 and PD-1) on CD4 + CXCR5 + T cells was increased in ATB group. TB-specific antigen stimulation induced higher expression of inhibitory receptors than phytohemagglutinin stimulation in ATB group. In contrast, TB antigen stimulation did not induce a significantly increased expression of IL-21 and Ki-67 on CD4 + CXCR5 + T cells. However, blockade of inhibitory receptors Tim-3 and PD-1 not only increased the frequency of CD4 + CXCR5 + T cells, but also restored their proliferation and cytokine secretion potential. An increased expression of inhibitory receptors involves the depletion of CD4 + CXCR5 + T cells, and blockade of inhibitory receptors can restore the function of CD4 + CXCR5 + T cells in ATB patients. Copyright © 2018. Published by Elsevier Ltd.

5-HT2A receptor activation is necessary for CO2-induced arousal

PubMed Central

Smith, Haleigh R.; MacAskill, Amanda; Richerson, George B.

2015-01-01

Hypercapnia-induced arousal from sleep is an important protective mechanism pertinent to a number of diseases. Most notably among these are the sudden infant death syndrome, obstructive sleep apnea and sudden unexpected death in epilepsy. Serotonin (5-HT) plays a significant role in hypercapnia-induced arousal. The mechanism of 5-HT's role in this protective response is unknown. Here we sought to identify the specific 5-HT receptor subtype(s) involved in this response. Wild-type mice were pretreated with antagonists against 5-HT receptor subtypes, as well as antagonists against adrenergic, cholinergic, histaminergic, dopaminergic, and orexinergic receptors before challenge with inspired CO2 or hypoxia. Antagonists of 5-HT2A receptors dose-dependently blocked CO2-induced arousal. The 5-HT2C receptor antagonist, RS-102221, and the 5-HT1A receptor agonist, 8-OH-DPAT, attenuated but did not completely block CO2-induced arousal. Blockade of non-5-HT receptors did not affect CO2-induced arousal. None of these drugs had any effect on hypoxia-induced arousal. 5-HT2 receptor agonists were given to mice in which 5-HT neurons had been genetically eliminated during embryonic life (Lmx1bf/f/p) and which are known to lack CO2-induced arousal. Application of agonists to 5-HT2A, but not 5-HT2C, receptors, dose-dependently restored CO2-induced arousal in these mice. These data identify the 5-HT2A receptor as an important mediator of CO2-induced arousal and suggest that, while 5-HT neurons can be independently activated to drive CO2-induced arousal, in the absence of 5-HT neurons and endogenous 5-HT, 5-HT receptor activation can act in a permissive fashion to facilitate CO2-induced arousal via another as yet unidentified chemosensor system. PMID:25925320

The effects of N-Methyl-D-Aspartate receptor blockade during the early neurodevelopmental period on emotional behaviors and cognitive functions of adolescent Wistar rats.

PubMed

Kocahan, Sayad; Akillioglu, Kubra; Binokay, Secil; Sencar, Leman; Polat, Sait

2013-05-01

The N-Methyl-D-Aspartate (NMDA) receptor is expressed abundantly in the brain and plays an important role in neuronal development, learning and memory, neurodegenerative diseases, and neurogenesis. In this study, we evaluated the effects of NMDA receptor blockade during the early neurodevelopmental period on exploratory locomotion, anxiety-like behaviors and cognitive functions of adolescent Wistar rats. NMDA receptor hypofunction was induced 7-10 days after birth using MK-801 in rats (0.25 mg/kg twice a day for 4 days via intraperitoneal injection). The open-field (OF), elevated plus maze (EPM) and passive avoidance (PA) tests were used to evaluate exploratory locomotion, anxiety-like behaviors and cognitive functions. In the OF test, MK-801 caused an increase in locomotion behavior (p < 0.01) and in the frequency of rearing (p < 0.05). In the EPM test, MK-801 treatment increased the time spent in the open arms, the number of open arm entries and the amount of head dipping (p < 0.01). MK-801 treatment caused no statistical difference compared to the control group in the PA test (p > 0.05). Chronic NMDA receptor blockade during the critical period of maturation for the glutamatergic brain system (postnatal days 7-10) produces locomotor hyperactivity and decreased anxiety levels, but has no significant main effect on cognitive function during adolescence.

Neural control of colonic cell proliferation.

PubMed

Tutton, P J; Barkla, D H

1980-03-15

The mitotic rate in rat colonic crypts and in dimethylhydrazine-induced colonic carcinomas was measured using a stathmokinetic technique. In sympathectomized animals cell proliferation was retarded in the crypts but not in the tumors, whereas in animals treated with Metaraminol, a drug which releases norepinephrine from nerve terminals, crypt cell but not tumor cell proliferation was accelerated. Blockade of alpha-adrenoceptors also inhibited crypt cell proliferation. However, stimulation of beta-adrenoceptors inhibited and blockade of beta-adrenoceptors accelerated tumor cell proliferation without influencing crypt cell proliferation. Injection of either serotonin or histamine stimulated tumor but not crypt cell proliferation and blockade or serotonin receptors or histamine H2-receptors inhibited tumor cell proliferation. It is postulated that cell proliferation in the colonic crypts, like that in the jejunal crypts, is under both endocrine and autonomic neural control whereas colonic tumor cell division is subject to endocrine regulation alone.

Enhancement of islet engraftment and achievement of long-term islet allograft survival by Toll-like receptor 4 blockade.

PubMed

Giovannoni, Laurianne; Muller, Yannick D; Lacotte, Stéphanie; Parnaud, Géraldine; Borot, Sophie; Meier, Raphaël P H; Lavallard, Vanessa; Bédat, Benoît; Toso, Christian; Daubeuf, Bruno; Elson, Greg; Shang, Limin; Morel, Philippe; Kosco-Vilbois, Marie; Bosco, Domenico; Berney, Thierry

2015-01-01

Toll-like receptors are key players in sterile inflammation phenomena and can link the innate and adaptive immune systems by enhancing graft immunogenicity. They are also considered mediators of types 1 and 2 diabetes development. The aim of the present study was to assess the role of Toll-like receptor-4 (TLR4) in mediating the inflammatory and immune responses to pancreatic islets, thereby promoting inflammatory destruction and immune rejection of islet grafts. Experiments were conducted in murine and human in vitro systems and in vivo murine islet transplant models, using species-specific anti-TLR4 monoclonal antibodies. In vitro, mixed lymphocyte-islet reaction experiments were performed to assess T-cell activation and proliferation. In vivo, both a syngeneic (B6-to-B6) marginal mass islet transplant model to assess the impact of TLR4 blockade on islet engraftment and an allogeneic (DBA1-to-B6) model were used. In vitro TLR4 blockade decreased lipopolysaccharide-mediated β-cell apoptosis and T-cell activation and proliferation against allogeneic islets. In vivo, TLR4 blockade resulted in significantly better syngeneic marginal mass islet engraftment and in indefinite allogeneic islet graft survival. Tolerance was not observed because donor-specific skin graft rechallenge in nonrejecting animals resulted in rejection of both skin and islets, but without accelerated rejection as compared to naive animals. Taken together, our data indicate that TLR4 blockade leads to a significant improvement of syngeneic islet engraftment and of allogeneic islet graft survival. A mechanism of graft accommodation with concurrent inhibition of donor-specific immune memory is likely to be involved.

GABAA overactivation potentiates the effects of NMDA blockade during the brain growth spurt in eliciting locomotor hyperactivity in juvenile mice.

PubMed

Oliveira-Pinto, Juliana; Paes-Branco, Danielle; Cristina-Rodrigues, Fabiana; Krahe, Thomas E; Manhães, Alex C; Abreu-Villaça, Yael; Filgueiras, Cláudio C

2015-01-01

Both NMDA receptor blockade and GABAA receptor overactivation during the brain growth spurt may contribute to the hyperactivity phenotype reminiscent of attention-deficit/hyperactivity disorder. Here, we evaluated the effects of exposure to MK801 (a NMDA antagonist) and/or to muscimol (a GABAA agonist) during the brain growth spurt on locomotor activity of juvenile Swiss mice. This study was carried out in two separate experiments. In the first experiment, pups received a single i.p. injection of either saline solution (SAL), MK801 (MK, 0.1, 0.3 or 0.5 mg/kg) or muscimol (MU, 0.02, 0.1 or 0.5 mg/kg) at the second postnatal day (PND2), and PNDs 4, 6 and 8. In the second experiment, we investigated the effects of a combined injection of MK (0.1 mg/kg) and MU (doses: 0.02, 0.1 or 0.5 mg/kg) following the same injection schedule of the first experiment. In both experiments, locomotor activity was assessed for 15 min at PND25. While MK promoted a dose-dependent increase in locomotor activity, exposure to MU failed to elicit significant effects. The combined exposure to the highest dose of MU and the lowest dose of MK induced marked hyperactivity. Moreover, the combination of the low dose of MK and the high dose of MU resulted in a reduced activity in the center of the open field, suggesting an increased anxiety-like behavior. These findings suggest that, during the brain growth spurt, the blockade of NMDA receptors induces juvenile locomotor hyperactivity whereas hyperactivation of GABAA receptors does not. However, GABAA overactivation during this period potentiates the effects of NMDA blockade in inducing locomotor hyperactivity. Copyright © 2015 Elsevier Inc. All rights reserved.

Boronic acid-containing CXCR1/2 antagonists: optimization of metabolic stability, in vivo evaluation, and a proposed receptor binding model

PubMed Central

Maeda, Dean Y.; Peck, Angela M.; Schuler, Aaron D.; Quinn, Mark T.; Kirpotina, Liliya N.; Wicomb, Winston N.; Auten, Richard L.; Gundla, Rambabu; Zebala, John A.

2015-01-01

Blockade of undesired neutrophil migration to sites of inflammation remains an area of substantial pharmaceutical interest. To effect this blockade, a validated therapeutic target is antagonism of the chemokine receptor CXCR2. Herein we report the discovery of 6-(2-boronic acid-5-trifluoromethoxy-benzylsulfanyl)-N-(4-fluoro-phenyl)-nicotinamide 6, an antagonist with activity at both CXCR1 and CXCR2 receptors (IC50 values 31 and 21 nM, respectively). Compound 6 exhibited potent inhibition of neutrophil influx in a rat model of pulmonary inflammation, and is hypothesized to interact with a unique intracellular binding site on CXCR2. Compound 6 (SX-576) is undergoing further investigation as a potential therapy for pulmonary inflammation. PMID:25933594

Blockade of serotonin 5-HT2A receptors potentiates dopamine D2 activation-induced disruption of pup retrieval on an elevated plus maze, but has no effect on D2 blockade-induced one.

PubMed

Nie, Lina; Di, Tianqi; Li, Yu; Cheng, Peng; Li, Ming; Gao, Jun

2018-06-23

Appetitive aspect of rat maternal behavior, such as pup retrieval, is motivationally driven and sensitive to dopamine disturbances. Activation or blockade of dopamine D 2 receptors causes a similar disruption of pup retrieval, which may also reflect an increase in maternal anxiety and/or a disruption of executive function. Recent work indicates that serotonin 5-HT 2A receptors also play an important role in rat maternal behavior. Given the well-known modulation of 5-HT 2A on the mesolimbic and mesocortical dopamine functions, the present study examined the extent to which blockade of 5-HT 2A receptors on dopamine D 2 -mediated maternal effects using a pup retrieval on the elevated plus maze (EPM) test. Sprague-Dawley postpartum female rats were acutely injected with quinpirole (a D 2 agonist, 0.10 and 0.25 mg/kg, sc), or haloperidol (a D 2 antagonist, 0.1 or 0.2 mg/kg, sc), in combination of MDL100907 (a 5-HT 2A receptor antagonist, 1.0 mg/kg, sc, 30 min before quinpirole or haloperidol injection) or saline and tested at 30, 90 and 240 min after quinpirole or haloperidol injection on postpartum days 3 and 7. Quinpirole and haloperidol decreased the number of pup retrieved (an index of maternal motivation) and sequential retrieval score (an index of executive function), prolonged the pup retrieval latencies, reduced the percentage of time spent on the open arms (an index of maternal anxiety), and decreased the distance travelled on the maze in a dose-dependent and time-dependent fashion. MDL100907 treatment by itself had no effect on pup retrieval, but it exacerbated the quinpirole-induced disruption of pup retrieval, but had no effect on the haloperidol-induced one. These findings suggest a complex interactive effect between 5-HT 2A and D 2 receptors on one or several maternal processes (maternal motivation, anxiety and executive function), and support the idea that one molecular mechanism by which 5-HT 2A receptors mediate maternal behavior is through its modulation of D 2 receptors. Copyright © 2018. Published by Elsevier Inc.

N(N)-nicotinic blockade as an acute human model of autonomic failure

NASA Technical Reports Server (NTRS)

Jordan, J.; Shannon, J. R.; Black, B. K.; Lance, R. H.; Squillante, M. D.; Costa, F.; Robertson, D.

1998-01-01

Pure autonomic failure has been conceptualized as deficient sympathetic and parasympathetic innervation. Several recent observations in chronic autonomic failure, however, cannot be explained simply by loss of autonomic innervation, at least according to our current understanding. To simulate acute autonomic failure, we blocked N(N)-nicotinic receptors with intravenous trimethaphan (6+/-0.4 mg/min) in 7 healthy subjects (4 men, 3 women, aged 32+/-3 years, 68+/-4 kg, 171+/-5 cm). N(N)-Nicotinic receptor blockade resulted in near-complete interruption of sympathetic and parasympathetic efferents as indicated by a battery of autonomic function tests. With trimethaphan, small postural changes from the horizontal were associated with significant blood pressure changes without compensatory changes in heart rate. Gastrointestinal motility, pupillary function, saliva production, and tearing were profoundly suppressed with trimethaphan. Plasma norepinephrine level decreased from 1.1+/-0.12 nmol/L (180+/-20 pg/mL) at baseline to 0.23+/-0.05 nmol/L (39+/-8 pg/mL) with trimethaphan (P<.001). There was a more than 16-fold increase in plasma vasopressin (P<.01) and no change in plasma renin activity. We conclude that blockade of N(N)-cholinergic receptors is useful to simulate the hemodynamic alterations of acute autonomic failure in humans. The loss of function with acute N(N)-cholinergic blockade is more complete than in most cases of chronic autonomic failure. This difference may be exploited to elucidate the contributions of acute denervation and chronic adaptation to the pathophysiology of autonomic failure. N(N)-Cholinergic blockade may also be applied to study human cardiovascular physiology and pharmacology in the absence of confounding baroreflexes.

NMDA-receptor blockade by CPP impairs post-training consolidation of a rapidly acquired spatial representation in rat hippocampus.

PubMed

McDonald, Robert J; Hong, Nancy S; Craig, Laura A; Holahan, Matthew R; Louis, Meira; Muller, Robert U

2005-09-01

Recent evidence suggests that N-methyl-D-aspartate (NMDA)-receptor mediated plasticity in hippocampus has a more subtle role in memory-based behaviours than originally thought. One idea is that NMDA-based plasticity is essential for the consolidation of post-training memory but not for the initial encoding or for short-term memory. To further test this idea we used a three-phase variant of the hidden goal water maze task. In the first phase, rats were pre-trained to an initial location. Next, intense, massed training was done in a 2-h interval to teach the rats to go to a new location after either an injection of the NMDA receptor antagonist (6)-3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) or of vehicle. Finally, under drug-free conditions 24 h after new location training, a competition test was done between the original and new locations. We find that N-methyl-D-aspartate (NMDA)-receptor blockade has little or no effect on new location training. In contrast, when tested 24 h later, the strength of the trace for the new location learned during NMDA-receptor blockade was much weaker compared with the trace for the new location learned after saline injection. Further experiments showed similar effects when NMDA-receptors were blocked immediately after the new location training, suggesting that this is a memory consolidation effect. Our results therefore reinforce the notion that hippocampal NMDA-receptors participate in post-training memory consolidation but are not essential for the processes necessary to learn or retain navigational information in the short term.

Disparate effects of single endothelin A and B receptor blocker therapy on the progression of renal injury in advanced renovascular disease

PubMed Central

Chade, Alejandro R.; Stewart, Nicholas J.; Peavy, Patrick R.

2013-01-01

We hypothesized that chronic specific endothelin (ET)-A receptor blockade therapy would reverse renal dysfunction and injury in advanced experimental renovascular disease. To test this, unilateral renovascular disease was induced in 19 pigs and after 6 weeks, single-kidney hemodynamics and function was quantified in vivo using computed-tomography. All pigs with renovascular disease were divided such that 7 were untreated, 7 were treated with ET-A blockers, and 5 were treated with ET-B blockers. Four weeks later, all pigs were re-studied in vivo, then euthanized and ex vivo studies performed on the stenotic kidney to quantify microvascular density, remodeling, renal oxidative stress, inflammation, and fibrosis. RBF, GFR, and redox status were significantly improved in the stenotic kidney after ET-A but not ET-B blockade. Furthermore, only ET-A blockade therapy reversed renal microvascular rarefaction and diminished remodeling, which was accompanied by a marked decreased in renal inflammatory and fibrogenic activity. Thus, ET-A but not ET-B blockade ameliorated renal injury in pigs with advanced renovascular disease by stimulating microvascular proliferation and decreasing the progression of microvascular remodeling, renal inflammation and fibrosis in the stenotic kidney. These effects were functionally consequential since ET-A blockade improved single kidney microvascular endothelial function, RBF, and GFR, and decreased albuminuria. PMID:24352153

Renal mitochondrial impairment is attenuated by AT1 blockade in experimental Type I diabetes.

PubMed

de Cavanagh, Elena M V; Ferder, León; Toblli, Jorge E; Piotrkowski, Bárbara; Stella, Inés; Fraga, Cesar G; Inserra, Felipe

2008-01-01

To investigate whether ANG II type 1 (AT(1)) receptor blockade could protect kidney mitochondria in streptozotocin-induced Type 1 diabetes, we treated 8-wk-old male Sprague-Dawley rats with a single streptozotocin injection (65 mg/kg ip; STZ group), streptozotocin and drinking water containing either losartan (30 mg.kg(-1).day(-1); STZ+Los group) or amlodipine (3 mg.kg(-1).day(-1); STZ+Amlo group), or saline (intraperitoneally) and pure water (control group). Four-month-long losartan or amlodipine treatments started 30 days before streptozotocin injection to improve the antioxidant defenses. The number of renal lesions, plasma glucose and lipid levels, and proteinuria were higher and creatinine clearance was lower in STZ and STZ+Amlo compared with STZ+Los and control groups. Glycemia was higher in STZ+Los compared with control. Blood pressure, basal mitochondrial membrane potential and mitochondrial pyruvate content, and renal oxidized glutathione levels were higher and NADH/cytochrome c oxidoreductase activity was lower in STZ compared with the other groups. In STZ and STZ+Amlo groups, mitochondrial H(2)O(2) production rate was higher and uncoupling protein-2 content, cytochrome c oxidase activity, and renal glutathione level were lower than in STZ+Los and control groups. Mitochondrial nitric oxide synthase activity was higher in STZ+Amlo compared with the other groups. Mitochondrial pyruvate content and H(2)O(2) production rate negatively contributed to electron transfer capacity and positively contributed to renal lesions. Uncoupling protein-2 content negatively contributed to mitochondrial H(2)O(2) production rate and renal lesions. Renal glutathione reduction potential positively contributed to mitochondria electron transfer capacity. In conclusion, AT(1) blockade protects kidney mitochondria and kidney structure in streptozotocin-induced diabetes independently of blood pressure and glycemia.

Interleukin-15 receptor blockade in non-human primate kidney transplantation.

PubMed

Haustein, Silke; Kwun, Jean; Fechner, John; Kayaoglu, Ayhan; Faure, Jean-Pierre; Roenneburg, Drew; Torrealba, Jose; Knechtle, Stuart J

2010-04-27

Interleukin (IL)-15 is a chemotactic factor to T cells. It induces proliferation and promotes survival of activated T cells. IL-15 receptor blockade in mouse cardiac and islet allotransplant models has led to long-term engraftment and a regulatory T-cell environment. This study investigated the efficacy of IL-15 receptor blockade using Mut-IL-15/Fc in an outbred non-human primate model of renal allotransplantation. Male cynomolgus macaque donor-recipient pairs were selected based on ABO typing, major histocompatibility complex class I typing, and carboxy-fluorescein diacetate succinimidyl ester-based mixed lymphocyte responses. Once animals were assigned to one of six treatment groups, they underwent renal transplantation and bilateral native nephrectomy. Serum creatinine level was monitored twice weekly and as indicated, and protocol biopsies were performed. Rejection was defined as a increase in serum creatinine to 1.5 mg/dL or higher and was confirmed histologically. Complete blood counts and flow cytometric analyses were performed periodically posttransplant; pharmacokinetic parameters of Mut-IL-15/Fc were assessed. Compared with control animals, Mut-IL-15/Fc-treated animals did not demonstrate increased graft survival despite adequate serum levels of Mut-IL-15/Fc. Flow cytometric analysis of white blood cell subgroups demonstrated a decrease in CD8 T-cell and natural killer cell numbers, although this did not reach statistical significance. Interestingly, two animals receiving Mut-IL-15/Fc developed infectious complications, but no infection was seen in control animals. Renal pathology varied widely. Peritransplant IL-15 receptor blockade does not prolong allograft survival in non-human primate renal transplantation; however, it reduces the number of CD8 T cells and natural killer cells in the peripheral blood.

Norepinephrine regulates cocaine-primed reinstatement via α1-adrenergic receptors in the medial prefrontal cortex.

PubMed

Schmidt, Karl T; Schroeder, Jason P; Foster, Stephanie L; Squires, Katherine; Smith, Brilee M; Pitts, Elizabeth G; Epstein, Michael P; Weinshenker, David

2017-06-01

Drug-primed reinstatement of cocaine seeking in rats is thought to reflect relapse-like behavior and is mediated by the integration of signals from mesocorticolimbic dopaminergic projections and corticostriatal glutamatergic innervation. Cocaine-primed reinstatement can also be attenuated by systemic administration of dopamine β-hydroxylase (DBH) inhibitors, which prevent norepinephrine (NE) synthesis, or by α1-adrenergic receptor (α1AR) antagonists, indicating functional modulation by the noradrenergic system. In the present study, we sought to further discern the role of NE in cocaine-seeking behavior by determining whether α1AR activation can induce reinstatement on its own or is sufficient to permit cocaine-primed reinstatement in the absence of all other AR signaling, and identifying the neuroanatomical substrate within the mesocorticolimbic reward system harboring the critical α1ARs. We found that while intracerebroventricular infusion of the α1AR agonist phenylephrine did not induce reinstatement on its own, it did overcome the blockade of cocaine-primed reinstatement by the DBH inhibitor nepicastat. Furthermore, administration of the α1AR antagonist terazosin in the medial prefrontal cortex (mPFC), but not the ventral tegmental area (VTA) or nucleus accumbens (NAc) shell, attenuated cocaine-primed reinstatement. Combined, these data indicate that α1AR activation in the mPFC is required for cocaine-primed reinstatement, and suggest that α1AR antagonists merit further investigation as pharmacotherapies for cocaine dependence. Copyright © 2017 Elsevier Ltd. All rights reserved.

Neuropeptide systems and new treatments for nicotine addiction

PubMed Central

Bruijnzeel, Adriaan W.

2017-01-01

RATIONALE The mildly euphoric and cognitive enhancing effects of nicotine play a role in the initiation of smoking, while dysphoria and anxiety associated with smoking cessation contribute to relapse. After the acute withdrawal phase, smoking cues, a few cigarettes (i.e., lapse), and stressors can cause relapse. Human and animal studies have shown that neuropeptides play a critical role in nicotine addiction. OBJECTIVES The goal of this paper is to describe the role of neuropeptide systems in the initiation of nicotine intake, nicotine withdrawal, and the reinstatement of extinguished nicotine seeking. RESULTS The reviewed studies indicate that several drugs that target neuropeptide systems diminish the rewarding effects of nicotine by preventing the activation of dopaminergic systems. Other peptide-based drugs diminish the hyperactivity of brain stress systems and diminish withdrawal-associated symptom severity. Blockade of hypocretin-1 and nociceptin receptors and stimulation of galanin and neurotensin receptors diminishes the rewarding effects of nicotine. Both corticotropin-releasing factor type 1 and kappa-opioid receptor antagonists diminish dysphoria and anxiety-like behavior associated with nicotine withdrawal and inhibit stress-induced reinstatement of nicotine seeking. Furthermore, blockade of vasopressin 1b receptors diminishes dysphoria during nicotine withdrawal and melanocortin 4 receptor blockade prevents stress-induced reinstatement of nicotine seeking. The role of neuropeptide systems in nicotine-primed and cue-induced reinstatement is largely unexplored, but there is evidence for a role of hypocretin-1 receptors in cue-induced reinstatement of nicotine seeking. CONCLUSION Drugs that target neuropeptide systems might decrease the euphoric effects of smoking and improve relapse rates by diminishing withdrawal symptoms and improving stress resilience. PMID:28028605

The antihypertensive effectiveness and safety of dual RAAS blockade with aliskiren and valsartan.

PubMed

Chrysant, Steven G

2010-03-01

The renin-angiotensin-aldosterone system (RAAS) is a major factor for the development and maintenance of hypertension and a major cause for cardiovascular remodeling and cardiovascular complications through its active peptide angiotensin (Ang) II. Blockade of RAAS with ACE inhibitors (ACEIs) results in suppression of Ang II levels, which eventually return to baseline levels after prolonged ACEI administration. This leads to an escape phenomenon through generation of Ang II from enzymes other than ACE and led to the hypothesis that dual blockade of RAAS with an ACEI/Ang receptor blocker (ARB) combination could lead to total blockade of RAAS, since ARBs block the action of Ang II at the AT1 receptor level, irrespective of the mechanism of Ang II generation and will have an additive blood pressure (BP)-lowering effect. However, this hypothesis has not materialized clinically, as the ACEI/ARB combination produces modest BP reductions that are not significantly greater than monotherapy with the component drugs, and is frequently associated with higher incidence of side effects. A new dual RAAS blockade with the direct renin inhibitor aliskiren and the ARB valsartan produces greater BP reductions than monotherapy with the component drugs and is safe and well tolerated. The combination of aliskiren with valsartan, and with other antihypertensive drugs is discussed. Copyright 2010 Prous Science, S.A.U. or its licensors. All rights reserved.

[Comparative analysis of metabotropic and ionotropic glutamate striatal receptors blockade influence on rats locomotor behaviour].

PubMed

Iakimovskiĭ, A F; Kerko, T V

2013-02-01

The influence of NMDA and metabotropic neostriatal glutamate receptors blockade to avoidance conditioning (in shuttle box) and free locomotor behavior (in open field) in chronic experiments in rats were investigated. The glutamate receptor antagonists were injected bilateral into striatum separately and with the GABA-A receptor antagonist picrotoxin (2 microg), that produced in rats the impairment of avoidance conditioning and choreo-myoklonic hyperkinesis. The most effective in preventing of negative picrotoxin influence on behavior was 5-type metabotropic glutamate receptors antagonist MTEP (3 microg). Separately injected MTEP did not influence on avoidance conditioning and free locomotor behavior. Unlike that, 1-type metabotropic glutamate receptors antagonist EMQMCM (3 microg) impaired normal locomotor behavior and did not prevent the picrotoxin effects. The NMDA glutamate receptors MK 801 (disocilpin--1 and 5 microg) impaired the picrotoxin-induced hyperkinesis, but did not to prevent the negative effects on avoidance conditioning; separately injected MK 801 reduced free locomotor activity. Based on location of investigated receptor types in neostriatal neurons membranes, we proposed that the most effective influence on 5-type metabotropic glutamate receptors is associated with their involvement in "indirect" efferent pathway, suffered in hyperkinetic extrapyramidal motor dysfunction--Huntington's chorea in human.

Involvement of α₂-adrenoceptors, imidazoline, and endothelin-A receptors in the effect of agmatine on morphine and oxycodone-induced hypothermia in mice.

PubMed

Bhalla, Shaifali; Andurkar, Shridhar V; Gulati, Anil

2013-10-01

Potentiation of opioid analgesia by endothelin-A (ET(A)) receptor antagonist, BMS182874, and imidazoline receptor/α₂-adrenoceptor agonists such as clonidine and agmatine are well known. It is also known that agmatine blocks morphine hyperthermia in rats. However, the effect of agmatine on morphine or oxycodone hypothermia in mice is unknown. The present study was carried out to study the role of α₂-adrenoceptors, imidazoline, and ET(A) receptors in morphine and oxycodone hypothermia in mice. Body temperature was determined over 6 h in male Swiss Webster mice treated with morphine, oxycodone, agmatine, and combination of agmatine with morphine or oxycodone. Yohimbine, idazoxan, and BMS182874 were used to determine involvement of α₂-adrenoceptors, imidazoline, and ET(A) receptors, respectively. Morphine and oxycodone produced significant hypothermia that was not affected by α₂-adrenoceptor antagonist yohimbine, imidazoline receptor/α₂ adrenoceptor antagonist idazoxan, or ET(A) receptor antagonist, BMS182874. Agmatine did not produce hypothermia; however, it blocked oxycodone but not morphine-induced hypothermia. Agmatine-induced blockade of oxycodone hypothermia was inhibited by idazoxan and yohimbine. The blockade by idazoxan was more pronounced compared with yohimbine. Combined administration of BMS182874 and agmatine did not produce changes in body temperature in mice. However, when BMS182874 was administered along with agmatine and oxycodone, it blocked agmatine-induced reversal of oxycodone hypothermia. This is the first report demonstrating that agmatine does not affect morphine hypothermia in mice, but reverses oxycodone hypothermia. Imidazoline receptors and α₂-adrenoceptors are involved in agmatine-induced reversal of oxycodone hypothermia. Our findings also suggest that ET(A) receptors may be involved in blockade of oxycodone hypothermia by agmatine. © 2012 The Authors Fundamental and Clinical Pharmacology © 2012 Société Française de Pharmacologie et de Thérapeutique.

Muscarinic cholinergic receptor binding: in vivo depiction using single photon emission computed tomography and radioiodinated quinuclidinyl benzilate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drayer, B.; Jaszczak, R.; Coleman, E.

1982-06-01

An attempt was made to characterize, in vivo, specific binding to the muscarinic cholinergic receptor in the calf using the radioiodinated ligand quinuclidinyl benzilate (/sup 123/I-OH-QNB) and single photon detection emission computed tomography (SPECT). The supratentorial brain activity was significantly increased after the intravenous infusion of /sup 123/I-OH-QNB as compared to free /sup 123/I. Scopolamine, a muscarinic cholinergic receptor antagonist, decreased the measured brain activity when infused prior to /sup 123/I-OH-QNB consistent with pharmacologic blockade of specific receptor binding. Quantitative in vitro tissue distribution studies obtained following SPECT imaging were consistent with regionally distinct specific receptor binding in the striatummore » and cortical gray matter, nonspecific binding in the cerebellum, and pharmacologic blockade of specific binding sites with scopolamine. Although /sup 123/I-OH-QNB is not the ideal radioligand, our limited success will hopefully encourage the development of improved binding probes for SPECT imaging and quantitation.« less

Dopamine Receptor-Specific Contributions to the Computation of Value.

PubMed

Burke, Christopher J; Soutschek, Alexander; Weber, Susanna; Raja Beharelle, Anjali; Fehr, Ernst; Haker, Helene; Tobler, Philippe N

2018-05-01

Dopamine is thought to play a crucial role in value-based decision making. However, the specific contributions of different dopamine receptor subtypes to the computation of subjective value remain unknown. Here we demonstrate how the balance between D1 and D2 dopamine receptor subtypes shapes subjective value computation during risky decision making. We administered the D2 receptor antagonist amisulpride or placebo before participants made choices between risky options. Compared with placebo, D2 receptor blockade resulted in more frequent choice of higher risk and higher expected value options. Using a novel model fitting procedure, we concurrently estimated the three parameters that define individual risk attitude according to an influential theoretical account of risky decision making (prospect theory). This analysis revealed that the observed reduction in risk aversion under amisulpride was driven by increased sensitivity to reward magnitude and decreased distortion of outcome probability, resulting in more linear value coding. Our data suggest that different components that govern individual risk attitude are under dopaminergic control, such that D2 receptor blockade facilitates risk taking and expected value processing.

NMDA-Type Glutamate Receptor Activation Promotes Vascular Remodeling and Pulmonary Arterial Hypertension.

PubMed

Dumas, Sébastien J; Bru-Mercier, Gilles; Courboulin, Audrey; Quatredeniers, Marceau; Rücker-Martin, Catherine; Antigny, Fabrice; Nakhleh, Morad K; Ranchoux, Benoit; Gouadon, Elodie; Vinhas, Maria-Candida; Vocelle, Matthieu; Raymond, Nicolas; Dorfmüller, Peter; Fadel, Elie; Perros, Frédéric; Humbert, Marc; Cohen-Kaminsky, Sylvia

2018-05-29

Excessive proliferation and apoptosis resistance in pulmonary vascular cells underlie vascular remodeling in pulmonary arterial hypertension (PAH). Specific treatments for PAH exist, mostly targeting endothelial dysfunction, but high pulmonary arterial pressure still causes heart failure and death. Pulmonary vascular remodeling may be driven by metabolic reprogramming of vascular cells to increase glutaminolysis and glutamate production. The N -methyl-d-aspartate receptor (NMDAR), a major neuronal glutamate receptor, is also expressed on vascular cells, but its role in PAH is unknown. We assessed the status of the glutamate-NMDAR axis in the pulmonary arteries of patients with PAH and controls through mass spectrometry imaging, Western blotting, and immunohistochemistry. We measured the glutamate release from cultured pulmonary vascular cells using enzymatic assays and analyzed NMDAR regulation/phosphorylation through Western blot experiments. The effect of NMDAR blockade on human pulmonary arterial smooth muscle cell proliferation was determined using a BrdU incorporation assay. We assessed the role of NMDARs in vascular remodeling associated to pulmonary hypertension, in both smooth muscle-specific NMDAR knockout mice exposed to chronic hypoxia and the monocrotaline rat model of pulmonary hypertension using NMDAR blockers. We report glutamate accumulation, upregulation of the NMDAR, and NMDAR engagement reflected by increases in GluN1-subunit phosphorylation in the pulmonary arteries of human patients with PAH. K v channel inhibition and type A-selective endothelin receptor activation amplified calcium-dependent glutamate release from human pulmonary arterial smooth muscle cell, and type A-selective endothelin receptor and platelet-derived growth factor receptor activation led to NMDAR engagement, highlighting crosstalk between the glutamate-NMDAR axis and major PAH-associated pathways. The platelet-derived growth factor-BB-induced proliferation of human pulmonary arterial smooth muscle cells involved NMDAR activation and phosphorylated GluN1 subunit localization to cell-cell contacts, consistent with glutamatergic communication between proliferating human pulmonary arterial smooth muscle cells via NMDARs. Smooth-muscle NMDAR deficiency in mice attenuated the vascular remodeling triggered by chronic hypoxia, highlighting the role of vascular NMDARs in pulmonary hypertension. Pharmacological NMDAR blockade in the monocrotaline rat model of pulmonary hypertension had beneficial effects on cardiac and vascular remodeling, decreasing endothelial dysfunction, cell proliferation, and apoptosis resistance while disrupting the glutamate-NMDAR pathway in pulmonary arteries. These results reveal a dysregulation of the glutamate-NMDAR axis in the pulmonary arteries of patients with PAH and identify vascular NMDARs as targets for antiremodeling treatments in PAH. © 2018 American Heart Association, Inc.

Vascular Effects of Endothelin Receptor Antagonists Depends on Their Selectivity for ETA Versus ETB Receptors and on the Functionality of Endothelial ETB Receptors.

PubMed

Iglarz, Marc; Steiner, Pauline; Wanner, Daniel; Rey, Markus; Hess, Patrick; Clozel, Martine

2015-10-01

The goal of this study was to characterize the role of Endothelin (ET) type B receptors (ETB) on vascular function in healthy and diseased conditions and demonstrate how it affects the pharmacological activity of ET receptor antagonists (ERAs). The contribution of the ETB receptor to vascular relaxation or constriction was characterized in isolated arteries from healthy and diseased rats with systemic (Dahl-S) or pulmonary hypertension (monocrotaline). Because the role of ETB receptors is different in pathological vis-à-vis normal conditions, we compared the efficacy of ETA-selective and dual ETA/ETB ERAs on blood pressure in hypertensive rats equipped with telemetry. In healthy vessels, ETB receptors stimulation with sarafotoxin S6c induced vasorelaxation and no vasoconstriction. In contrast, in arteries of rats with systemic or pulmonary hypertension, endothelial ETB-mediated relaxation was lost while vasoconstriction on stimulation by sarafotoxin S6c was observed. In hypertensive rats, administration of the dual ETA/ETB ERA macitentan on top of a maximal effective dose of the ETA-selective ERA ambrisentan further reduced blood pressure, indicating that ETB receptors blockade provides additional benefit. Taken together, these data suggest that in pathology, dual ETA/ETB receptor antagonism can provide superior vascular effects compared with ETA-selective receptor blockade.

Differential effects of presynaptic versus postsynaptic adenosine A2A receptor blockade on Δ9-tetrahydrocannabinol (THC) self-administration in squirrel monkeys.

PubMed

Justinová, Zuzana; Redhi, Godfrey H; Goldberg, Steven R; Ferré, Sergi

2014-05-07

Different doses of an adenosine A2A receptor antagonist MSX-3 [3,7-dihydro-8-[(1E)-2-(3-ethoxyphenyl)ethenyl]-7 methyl-3-[3-(phosphooxy)propyl-1-(2 propynil)-1H-purine-2,6-dione] were found previously to either decrease or increase self-administration of cannabinoids delta-9-tetrahydrocannabinol (THC) or anandamide in squirrel monkeys. It was hypothesized that the decrease observed with a relatively low dose of MSX-3 was related to blockade of striatal presynaptic A2A receptors that modulate glutamatergic neurotransmission, whereas the increase observed with a higher dose was related to blockade of postsynaptic A2A receptors localized in striatopallidal neurons. This hypothesis was confirmed in the present study by testing the effects of the preferential presynaptic and postsynaptic A2A receptor antagonists SCH-442416 [2-(2-furanyl)-7-[3-(4-methoxyphenyl)propyl]-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine] and KW-6002 [(E)-1, 3-diethyl-8-(3,4-dimethoxystyryl)-7-methyl-3,7-dihydro-1H-purine-2,6-dione], respectively, in squirrel monkeys trained to intravenously self-administer THC. SCH-442416 produced a significant shift to the right of the THC self-administration dose-response curves, consistent with antagonism of the reinforcing effects of THC. Conversely, KW-6002 produced a significant shift to the left, consistent with potentiation of the reinforcing effects of THC. These results show that selectively blocking presynaptic A2A receptors could provide a new pharmacological approach to the treatment of marijuana dependence and underscore corticostriatal glutamatergic neurotransmission as a possible main mechanism involved in the rewarding effects of THC.

Boronic acid-containing CXCR1/2 antagonists: Optimization of metabolic stability, in vivo evaluation, and a proposed receptor binding model.

PubMed

Maeda, Dean Y; Peck, Angela M; Schuler, Aaron D; Quinn, Mark T; Kirpotina, Liliya N; Wicomb, Winston N; Auten, Richard L; Gundla, Rambabu; Zebala, John A

2015-06-01

Blockade of undesired neutrophil migration to sites of inflammation remains an area of substantial pharmaceutical interest. To effect this blockade, a validated therapeutic target is antagonism of the chemokine receptor CXCR2. Herein we report the discovery of 6-(2-boronic acid-5-trifluoromethoxy-benzylsulfanyl)-N-(4-fluoro-phenyl)-nicotinamide 6, an antagonist with activity at both CXCR1 and CXCR2 receptors (IC50 values 31 and 21 nM, respectively). Compound 6 exhibited potent inhibition of neutrophil influx in a rat model of pulmonary inflammation, and is hypothesized to interact with a unique intracellular binding site on CXCR2. Compound 6 (SX-576) is undergoing further investigation as a potential therapy for pulmonary inflammation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Methamphetamine-induced stereotypy correlates negatively with patch-enhanced prodynorphin and arc mRNA expression in the rat caudate putamen: the role of mu opioid receptor activation.

PubMed

Horner, Kristen A; Noble, Erika S; Gilbert, Yamiece E

2010-06-01

Amphetamines induce stereotypy, which correlates with patch-enhanced c-Fos expression the patch compartment of caudate putamen (CPu). Methamphetamine (METH) treatment also induces patch-enhanced expression of prodynorphin (PD), arc and zif/268 in the CPu. Whether patch-enhanced activation of any of these genes correlates with METH-induced stereotypy is unknown, and the factors that contribute to this pattern of expression are poorly understood. Activation of mu opioid receptors, which are expressed by the neurons of the patch compartment, may underlie METH-induced patch-enhanced gene expression and stereotypy. The current study examined whether striatal mu opioid receptor blockade altered METH-induced stereotypy and patch-enhanced gene expression, and if there was a correlation between the two responses. Animals were intrastriatally infused with the mu antagonist CTAP (10 microg/microl), treated with METH (7.5 mg/kg, s.c.), placed in activity chambers for 3h, and then sacrificed. CTAP pretreatment attenuated METH-induced increases in PD, arc and zif/268 mRNA expression and significantly reduced METH-induced stereotypy. Patch-enhanced PD and arc mRNA expression in the dorsolateral CPu correlated negatively with METH-induced stereotypy. These data indicate that mu opioid receptor activation contributes to METH-induced gene expression in the CPu and stereotypy, and that patch-enhanced PD and arc expression may be a homeostatic response to METH treatment. Copyright 2010 Elsevier Inc. All rights reserved.

Methamphetamine-Induced Stereotypy Correlates Negatively with Patch-Enhanced Prodynorphin and ARC mRNA Expression in the Rat Caudate Putamen: The Role of Mu Opioid Receptor Activation

PubMed Central

Horner, Kristen A.; Noble, Erika S.; Gilbert, Yamiece E.

2010-01-01

Amphetamines induce stereotypy, which correlates with patch-enhanced c-Fos expression the patch compartment of caudate putamen (CPu). Methamphetamine (METH) treatment also induces patch-enhanced expression of prodynorphin (PD), arc and zif/268 in the CPu. Whether patch-enhanced activation of any of these genes correlates with METH-induced stereotypy is unknown, and the factors that contribute to this pattern of expression are poorly understood. Activation of mu opioid receptors, which are expressed by the neurons of the patch compartment, may underlie METH-induced patch-enhanced gene expression and stereotypy. The current study examined whether striatal mu opioid receptor blockade altered METH-induced stereotypy and patch-enhanced gene expression, and if there was a correlation between the two responses. Animals were intrastriatally infused with the mu antagonist CTAP (10 μg/μl), treated with METH (7.5 mg/kg, s.c.), placed in activity chambers for 3h, and then sacrificed. CTAP pretreatment attenuated METH-induced increases in PD, arc and zif/268 mRNA expression and significantly reduced METH-induced stereotypy. Patch-enhanced PD and arc mRNA expression in the dorsolateral CPu correlated negatively with METH-induced stereotypy. These data indicate that mu opioid receptor activation contributes to METH-induced gene expression in the CPu and stereotypy, and that patch-enhanced PD and arc expression may be a homeostatic response to METH treatment. PMID:20298714

Chronic ETA antagonist reverses hypertension and impairment of structure and function of peripheral small arteries in aortic stiffening.

PubMed

Guo, Xiaomei; Chen, Huan; Han, Ling; Haulon, Stephan; Kassab, Ghassan S

2018-02-15

Arterial stiffness may contribute to the pathogenesis of hypertension. The goal of this study is to elucidate the role of Endothelin-1 (ET-1) in aortic stiffening-induced hypertension through ET A receptor activation. An increase in aortic stiffness was created by use of a non-constrictive restraint, NCR on the abdominal aortic surface. A group of rats underwent aortic NCR or sham operation for 12 weeks and were then treated with ET A receptor antagonist BQ-123 for 3 weeks. We found that 12 weeks of aortic NCR significantly increased pulse and mean pressure and altered peripheral flow pattern, accompanied by an increased serum ET-1 level (p < 0.05). The increase in aortic stiffness (evidenced by an elevated pulse wave velocity) caused hypertrophic structural remodeling and decreased arterial compliance, along with an impaired endothelial function in peripheral small arteries. BQ-123 treatment only partially attenuated peripheral arterial hypertrophy and restored arterial compliance, but completely recovered endothelium function, and consequently restored local flow and lowered blood pressure. Our findings underscore the hemodynamic coupling between aortic stiffening and peripheral arterial vessels and flow dynamics through an ET A -dependent mechanism. ET A receptor blockade may have therapeutic potential for improving peripheral vessel structure and function in the treatment of aortic stiffness-induced hypertension.

L-Cysteine and L-AP4 microinjections in the rat caudal ventrolateral medulla decrease arterial blood pressure.

PubMed

Takemoto, Yumi

2014-12-01

The thiol amino acid L-cysteine increases arterial blood pressure (ABP) when injected into the cerebrospinal fluid space in conscious rats, indicating a pressor response to centrally acting L-cysteine. A prior synaptic membrane binding assay suggests that L-cysteine has a strong affinity for the L-2-amino-4-phosphonobutyric acid (L-AP4) binding site. The central action of L-cysteine may be vial-AP4 sensitive receptors. The present study investigated cardiovascular responses to L-cysteine and L-ap4 microinjected into the autonomic area of the caudal ventrolateral medulla (CVLM) where inhibitory neurons regulate ABP via pre-sympathetic vasomotor neurons. Both the injection of L-cysteine and L-AP4 in the CVLM sites identified with L-glutamate produced the same depressor and bradycardic responses in urethane-anesthetized rats. Neither a prior antagonist microinjection of MK801 for the N-methyl-D-aspartate (NMDA) receptor nor CNQX for the non-NMDA receptor attenuated the responses to L-cysteine, but the combination of the two receptor blocking with an additional prior injection abolished the response. In contrast, either receptor blockade alone abolished the response to L-AP4, indicating distinct mechanisms between responses to L-cysteine and L-AP4 in the CVLM. The results indicate that the CVLM is a central active site for L-cysteine's cardiovascular response. Central L-cysteine's action could be independent of the L-AP4 sensitive receptors. Cardiovascular regulation may involve endogenous L-cysteine in the CVLM. Further multidisciplinary examinations are required to elaborate on L-cysteine's functional roles in the CVLM. Copyright © 2014 Elsevier B.V. All rights reserved.

Differential effects of m1 and m2 receptor antagonists in perirhinal cortex on visual recognition memory in monkeys

PubMed Central

Wu, Wei; Saunders, Richard C.; Mishkin, Mortimer; Turchi, Janita

2012-01-01

Microinfusions of the nonselective muscarinic antagonist scopolamine into perirhinal cortex impairs performance on visual recognition tasks, indicating that muscarinic receptors in this region play a pivotal role in recognition memory. To assess the mnemonic effects of selective blockade in perirhinal cortex of muscarinic receptor subtypes, we locally infused either the m1-selective antagonist pirenzepine or the m2-selective antagonist methoctramine in animals performing one-trial visual recognition, and compared these scores with those following infusions of equivalent volumes of saline. Compared to these control infusions, injections of pirenzepine, but not of methoctramine, significantly impaired recognition accuracy. Further, similar doses of scopolamine and pirenzepine yielded similar deficits, suggesting that the deficits obtained earlier with scopolamine were due mainly, if not exclusively, to blockade of m1 receptors. The present findings indicate that m1 and m2 receptors have functionally dissociable roles, and that the formation of new visual memories is critically dependent on the cholinergic activation of m1 receptors located on perirhinal cells. PMID:22561485

Differential effects of m1 and m2 receptor antagonists in perirhinal cortex on visual recognition memory in monkeys.

PubMed

Wu, Wei; Saunders, Richard C; Mishkin, Mortimer; Turchi, Janita

2012-07-01

Microinfusions of the nonselective muscarinic antagonist scopolamine into perirhinal cortex impairs performance on visual recognition tasks, indicating that muscarinic receptors in this region play a pivotal role in recognition memory. To assess the mnemonic effects of selective blockade in perirhinal cortex of muscarinic receptor subtypes, we locally infused either the m1-selective antagonist pirenzepine or the m2-selective antagonist methoctramine in animals performing one-trial visual recognition, and compared these scores with those following infusions of equivalent volumes of saline. Compared to these control infusions, injections of pirenzepine, but not of methoctramine, significantly impaired recognition accuracy. Further, similar doses of scopolamine and pirenzepine yielded similar deficits, suggesting that the deficits obtained earlier with scopolamine were due mainly, if not exclusively, to blockade of m1 receptors. The present findings indicate that m1 and m2 receptors have functionally dissociable roles, and that the formation of new visual memories is critically dependent on the cholinergic activation of m1 receptors located on perirhinal cells. Published by Elsevier Inc.

Mineralocorticoid receptor blockade in addition to angiotensin converting enzyme inhibitor or angiotensin II receptor blocker treatment: an emerging paradigm in diabetic nephropathy: a systematic review.

PubMed

Mavrakanas, Thomas A; Gariani, Karim; Martin, Pierre-Yves

2014-02-01

Blockade of the renin-angiotensin-aldosterone system (RAAS) is a standard therapeutic intervention in diabetic patients with chronic kidney disease (CKD). Concomitant mineralocorticoid receptor blockade has been studied as a novel approach to further slow down CKD progression. We used PubMed and EMBASE databases to search for relevant literature. We included in our review eight studies in patients of at least 18 years of age, with a diagnosis of type 1 or type 2 diabetes mellitus and diabetic nephropathy, under an angiotensin converting enzyme inhibitor (ACEI) and/or an angiotensin II receptor blocker (ARB) as standard treatment. A subset of patients in each study also received a mineralocorticoid receptor blocker (MRB) (either spironolactone or eplerenone) in addition to standard treatment. Combined treatment with a mineralocorticoid receptor blocker further reduced albuminuria by 23 to 61% compared with standard treatment. Estimated glomerular filtration rate values upon study completion slightly decreased under combined treatment. Blood pressure levels upon study completion were significantly lower with combined treatment in three studies. Hyperkalemia prevalence increased in patients under combined treatment raising dropout rate up to 17%. Therefore, combined treatment by an ACEI/ARB and a MRB may further decrease albuminuria in diabetic nephropathy. This effect may be due to the specific properties of the MRB treatment. Clinicians should regularly check potassium levels because of the increased risk of hyperkalemia. Available evidence should be confirmed by an adequately powered comparative trial of the standard treatment (ACEI or ARB) versus combined treatment by an ACEI/ARB and a MRB. Copyright © 2013 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

Advanced oxidation protein products induce chondrocyte apoptosis via receptor for advanced glycation end products-mediated, redox-dependent intrinsic apoptosis pathway.

PubMed

Wu, Qian; Zhong, Zhao-Ming; Zhu, Si-Yuan; Liao, Cong-Rui; Pan, Ying; Zeng, Ji-Huan; Zheng, Shuai; Ding, Ruo-Ting; Lin, Qing-Song; Ye, Qing; Ye, Wen-Bin; Li, Wei; Chen, Jian-Ting

2016-01-01

Pro-inflammatory cytokine-induced chondrocyte apoptosis is a primary cause of cartilage destruction in the progression of rheumatoid arthritis (RA). Advanced oxidation protein products (AOPPs), a novel pro-inflammatory mediator, have been confirmed to accumulate in patients with RA. However, the effect of AOPPs accumulation on chondrocyte apoptosis and the associated cellular mechanisms remains unclear. The present study demonstrated that the plasma formation of AOPPs was enhanced in RA rats compared with normal. Then, chondrocyte were treated with AOPPs-modified rat serum albumin (AOPPs-RSA) in vitro. Exposure of chondrocyte to AOPPs activated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and increased expression of NADPH oxidase subunits, which was mediated by receptor for advanced glycation end products (RAGE), but not scavenger receptor CD36. Moreover, AOPPs challenge triggered NADPH oxidase-dependent ROS generation which induced mitochondrial dysfunction and endoplasmic reticulum stress resulted in activation of caspase family that eventually lead to apoptosis. Lastly, blockade of RAGE, instead of CD36, largely attenuated these signals. Our study demonstrated first time that AOPPs induce chondrocyte apoptosis via RAGE-mediated and redox-dependent intrinsic apoptosis pathway in vitro. These data implicates that AOPPs may represent a novel pathogenic factor that contributes to RA progression. Targeting AOPPs-triggered cellular mechanisms might emerge as a promising therapeutic option for patients with RA.

ABT-627, an endothelin ET(A) receptor-selective antagonist, attenuates tactile allodynia in a diabetic rat model of neuropathic pain.

PubMed

Jarvis, M F; Wessale, J L; Zhu, C Z; Lynch, J J; Dayton, B D; Calzadilla, S V; Padley, R J; Opgenorth, T J; Kowaluk, E A

2000-01-24

Tactile allodynia, the enhanced perception of pain in response to normally non-painful stimulation, represents a common complication of diabetic neuropathy. The activation of endothelin ET(A) receptors has been implicated in diabetes-induced reductions in peripheral neurovascularization and concomitant endoneurial hypoxia. Endothelin receptor activation has also been shown to alter the peripheral and central processing of nociceptive information. The present study was conducted to evaluate the antinociceptive effects of the novel endothelin ET(A) receptor-selective antagonist, 2R-(4-methoxyphenyl)-4S-(1,3-benzodioxol-5-yl)-1-(N, N-di(n-butyl)aminocarbonyl-methyl)-pyrrolidine-3R-carboxylic acid (ABT-627), in the streptozotocin-induced diabetic rat model of neuropathic pain. Rats were injected with 75 mg/kg streptozotocin (i. p.), and drug effects were assessed 8-12 weeks following streptozotocin treatment to allow for stabilization of blood glucose levels (>/=240 mg/dl) and tactile allodynia thresholds (

Hydronephrosis alters cardiac ACE2 and Mas receptor expression in mice.

PubMed

Zhang, Yanling; Ma, Lulu; Wu, Junyan; Chen, Tingting

2015-06-01

Hydronephrosis is characterized by substantial loss of tubules and affects renin secretion in the kidney. However, whether alterations of angiotensin-converting enzyme (ACE), ACE2 and Mas receptor in the heart are observed in hydronephrosis is unknown. Thus, we assessed these components in hydronephrotic mice treated with AT1 receptor blockade and ACE inhibitor. Hydronephrosis was induced by left ureteral ligation in Balb/C mice except sham-operated animals. The levels of cardiac ACE, ACE2 and Mas receptor were measured after treatment of losartan or enalapril. Hydronephrosis led to an increase of ACE level and a decrease of ACE2 and Mas receptor in the heart. Losartan decreased cardiac ACE level, but ACE2 and Mas receptor levels significantly increased in hydronephrotic mice (p < 0.01). Enalapril increased ACE2 levels (p < 0.01), but did not affect Mas receptor in the heart. Plasma renin activity (PRA) and Ang II decreased in hydronephrotic mice, but significantly increased after treatment with losartan or enalapril. Hydronephrosis increased cardiac ACE and suppressed ACE2 and Mas receptor levels. AT1 blockade caused sustained activation of cardiac ACE2 and Mas receptor, but ACE inhibitor had the limitation of such activation of Mas receptor in hydronephrotic animals. © The Author(s) 2015.

Serotonin modulates insect hemocyte phagocytosis via two different serotonin receptors

PubMed Central

Qi, Yi-xiang; Huang, Jia; Li, Meng-qi; Wu, Ya-su; Xia, Ren-ying; Ye, Gong-yin

2016-01-01

Serotonin (5-HT) modulates both neural and immune responses in vertebrates, but its role in insect immunity remains uncertain. We report that hemocytes in the caterpillar, Pieris rapae are able to synthesize 5-HT following activation by lipopolysaccharide. The inhibition of a serotonin-generating enzyme with either pharmacological blockade or RNAi knock-down impaired hemocyte phagocytosis. Biochemical and functional experiments showed that naive hemocytes primarily express 5-HT1B and 5-HT2B receptors. The blockade of 5-HT1B significantly reduced phagocytic ability; however, the blockade of 5-HT2B increased hemocyte phagocytosis. The 5-HT1B-null Drosophila melanogaster mutants showed higher mortality than controls when infected with bacteria, due to their decreased phagocytotic ability. Flies expressing 5-HT1B or 5-HT2B RNAi in hemocytes also showed similar sensitivity to infection. Combined, these data demonstrate that 5-HT mediates hemocyte phagocytosis through 5-HT1B and 5-HT2B receptors and serotonergic signaling performs critical modulatory functions in immune systems of animals separated by 500 million years of evolution. DOI: http://dx.doi.org/10.7554/eLife.12241.001 PMID:26974346

Partial mGlu₅ Negative Allosteric Modulators Attenuate Cocaine-Mediated Behaviors and Lack Psychotomimetic-Like Effects.

PubMed

Gould, Robert W; Amato, Russell J; Bubser, Michael; Joffe, Max E; Nedelcovych, Michael T; Thompson, Analisa D; Nickols, Hilary H; Yuh, Johannes P; Zhan, Xiaoyan; Felts, Andrew S; Rodriguez, Alice L; Morrison, Ryan D; Byers, Frank W; Rook, Jerri M; Daniels, John S; Niswender, Colleen M; Conn, P Jeffrey; Emmitte, Kyle A; Lindsley, Craig W; Jones, Carrie K

2016-03-01

Cocaine abuse remains a public health concern for which pharmacotherapies are largely ineffective. Comorbidities between cocaine abuse, depression, and anxiety support the development of novel treatments targeting multiple symptom clusters. Selective negative allosteric modulators (NAMs) targeting the metabotropic glutamate receptor 5 (mGlu5) subtype are currently in clinical trials for the treatment of multiple neuropsychiatric disorders and have shown promise in preclinical models of substance abuse. However, complete blockade or inverse agonist activity by some full mGlu5 NAM chemotypes demonstrated adverse effects, including psychosis in humans and psychotomimetic-like effects in animals, suggesting a narrow therapeutic window. Development of partial mGlu5 NAMs, characterized by their submaximal but saturable levels of blockade, may represent a novel approach to broaden the therapeutic window. To understand potential therapeutic vs adverse effects in preclinical behavioral assays, we examined the partial mGlu5 NAMs, M-5MPEP and Br-5MPEPy, in comparison with the full mGlu5 NAM MTEP across models of addiction and psychotomimetic-like activity. M-5MPEP, Br-5MPEPy, and MTEP dose-dependently decreased cocaine self-administration and attenuated the discriminative stimulus effects of cocaine. M-5MPEP and Br-5MPEPy also demonstrated antidepressant- and anxiolytic-like activity. Dose-dependent effects of partial and full mGlu5 NAMs in these assays corresponded with increasing in vivo mGlu5 occupancy, demonstrating an orderly occupancy-to-efficacy relationship. PCP-induced hyperlocomotion was potentiated by MTEP, but not by M-5MPEP and Br-5MPEPy. Further, MTEP, but not M-5MPEP, potentiated the discriminative-stimulus effects of PCP. The present data suggest that partial mGlu5 NAM activity is sufficient to produce therapeutic effects similar to full mGlu5 NAMs, but with a broader therapeutic index.

Loss of ErbB2-PI3K/Akt signaling prevents zinc pyrithione-induced cardioprotection during ischemia/reperfusion.

PubMed

Thokala, Sandhya; Inapurapu, Santhipriya; Bodiga, Vijaya Lakshmi; Vemuri, Praveen Kumar; Bodiga, Sreedhar

2017-04-01

The purpose of this study was to determine if zinc homeostasis is affected during ischemia/reperfusion, if so, whether zinc pyrithione limits myocardial cell death and improves hemodynamics when administered as an adjunct to reperfusion and if ErbB receptor tyrosine kinases that are important for the long-term structural integrity of the heart are indispensable for reperfusion salvage. Isolated perfused rat hearts were subjected to 35min of global ischemia and reperfused for 120min to determine the relative intracellular zinc levels by TSQ staining. The hearts were reperfused in the presence of incremental concentrations of zinc pyrithione for the first 10min during reperfusion. Silencing or blockade of ErbB2 using a monoclonal antibody, ErbB2 kinase inhibition and PI3kinase inhibition was used to study their critical role in zinc pyrithione-induced cardioprotection. We found that there was a profound decrease in intracellular zinc after ischemia/reperfusion resulting in increased apoptosis, caspase-3 activation, and infarct size. A dose-dependent reduction of infarct size with zinc pyrithione in the range of 5-20μmol/l (optimal protection was seen at 10μmol/l with infarct size of 16±2% vs. I/R vehicle, 33±2%, p<0.01). Increased TUNEL staining and caspase-3 activity observed after ischemia/reperfusion were attenuated by zinc pyrithione administration during the reperfusion. Moreover, this protection was sensitive to silencing and blockade of ErbB2, inhibition of ErbB2 kinase activity or PI3-kinase activity. Western blot analysis revealed that zinc pyrithione resulted in decreased caspase-3 activation, rapid stabilization of ErbB2/ErbB1 heterodimers, and increased activation of PI3K/Akt signaling cascade. Zinc pyrithione attenuates lethal perfusion-induced injury in a manner that is reliant on ErbB2/PI3K/Akt activity. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Improvement in Renal Hemodynamics following Combined Angiotensin II Infusion and AT1R Blockade in Aged Female Sheep following Fetal Unilateral Nephrectomy

PubMed Central

Singh, Reetu R.; Lankadeva, Yugeesh R.

2013-01-01

Renin-angiotensin system (RAS) is a powerful modulator of renal hemodynamic and fluid homeostasis. Up-regulation in components of intra-renal RAS occurs with ageing. Recently we reported that 2 year old uninephrectomised (uni-x) female sheep have low renin hypertension and reduced renal function. By 5 years of age, these uni-x sheep had augmented decrease in renal blood flow (RBF) compared to sham. We hypothesised that this decrease in RBF in 5 year old uni-x sheep was due to an up-regulation in components of the intra-renal RAS. In this study, renal responses to angiotensin II (AngII) infusion and AngII type 1 receptor (AT1R) blockade were examined in the same 5 year old sheep. We also administered AngII in the presence of losartan to increase AngII bioavailability to the AT2R in order to understand AT2R contribution to renal function in this model. Uni-x animals had significantly lower renal cortical content of renin, AngII (∼40%) and Ang 1–7 (∼60%) and reduced cortical expression of AT1R gene than sham animals. In response to both AngII infusion and AT1R blockade via losartan, renal hemodynamic responses and tubular sodium excretion were significantly attenuated in uni-x animals compared to sham. However, AngII infusion in the presence of losartan caused ∼33% increase in RBF in uni-x sheep compared to ∼14% in sham (P<0.05). This was associated with a significant decrease in renal vascular resistance in the uni-x animals (22% vs 15%, P<0.05) without any changes in systemic blood pressure. The present study shows that majority of the intra-renal RAS components are suppressed in this model of low renin hypertension. However, increasing the availability of AngII to AT2R by AT1R blockade improved renal blood flow in uni-x sheep. This suggests that manipulation of the AT2R maybe a potential therapeutic target for treatment of renal dysfunction associated with a congenital nephron deficit. PMID:23840884

Targeting the GM-CSF receptor for the treatment of CNS autoimmunity

PubMed Central

Ifergan, Igal; Davidson, Todd S.; Kebir, Hania; Xu, Dan; Palacios-Macapagal, Daphne; Cann, Jennifer; Rodgers, Jane M.; Hunter, Zoe N.; Pittet, Camille L.; Beddow, Sara; Jones, Clare A.; Prat, Alexandre; Sleeman, Matthew A.; Miller, Stephen D.

2017-01-01

In multiple sclerosis (MS), there is a growing interest in inhibiting the pro-inflammatory effects of granulocyte-macrophage colony-stimulating factor (GM-CSF). We sought to evaluate the therapeutic potential and underlying mechanisms of GM-CSF receptor alpha (Rα) blockade in animal models of MS. We show that GM-CSF signaling inhibition at peak of chronic experimental autoimmune encephalomyelitis (EAE) results in amelioration of disease progression. Similarly, GM-CSF Rα blockade in relapsing-remitting (RR)-EAE model prevented disease relapses and inhibited T cell responses specific for both the inducing and spread myelin peptides, while reducing activation of mDCs and inflammatory monocytes. In situ immunostaining of lesions from human secondary progressive MS (SPMS), but not primary progressive MS patients shows extensive recruitment of GM-CSF Rα+ myeloid cells. Collectively, this study reveals a pivotal role of GM-CSF in disease relapses and the benefit of GM-CSF Rα blockade as a potential novel therapeutic approach for treatment of RRMS and SPMS. PMID:28641926

Targeting the GM-CSF receptor for the treatment of CNS autoimmunity.

PubMed

Ifergan, Igal; Davidson, Todd S; Kebir, Hania; Xu, Dan; Palacios-Macapagal, Daphne; Cann, Jennifer; Rodgers, Jane M; Hunter, Zoe N; Pittet, Camille L; Beddow, Sara; Jones, Clare A; Prat, Alexandre; Sleeman, Matthew A; Miller, Stephen D

2017-11-01

In multiple sclerosis (MS), there is a growing interest in inhibiting the pro-inflammatory effects of granulocyte-macrophage colony-stimulating factor (GM-CSF). We sought to evaluate the therapeutic potential and underlying mechanisms of GM-CSF receptor alpha (Rα) blockade in animal models of MS. We show that GM-CSF signaling inhibition at peak of chronic experimental autoimmune encephalomyelitis (EAE) results in amelioration of disease progression. Similarly, GM-CSF Rα blockade in relapsing-remitting (RR)-EAE model prevented disease relapses and inhibited T cell responses specific for both the inducing and spread myelin peptides, while reducing activation of mDCs and inflammatory monocytes. In situ immunostaining of lesions from human secondary progressive MS (SPMS), but not primary progressive MS patients shows extensive recruitment of GM-CSF Rα + myeloid cells. Collectively, this study reveals a pivotal role of GM-CSF in disease relapses and the benefit of GM-CSF Rα blockade as a potential novel therapeutic approach for treatment of RRMS and SPMS. Copyright © 2017 Elsevier Ltd. All rights reserved.

B and T lymphocyte attenuator mediates inhibition of tumor-reactive CD8+ T cells in patients after allogeneic stem cell transplantation.

PubMed

Hobo, Willemijn; Norde, Wieger J; Schaap, Nicolaas; Fredrix, Hanny; Maas, Frans; Schellens, Karen; Falkenburg, J H Frederik; Korman, Alan J; Olive, Daniel; van der Voort, Robbert; Dolstra, Harry

2012-07-01

Allogeneic stem cell transplantation (allo-SCT) can cure hematological malignancies by inducing alloreactive T cell responses targeting minor histocompatibility antigens (MiHA) expressed on malignant cells. Despite induction of robust MiHA-specific T cell responses and long-term persistence of alloreactive memory T cells specific for the tumor, often these T cells fail to respond efficiently to tumor relapse. Previously, we demonstrated the involvement of the coinhibitory receptor programmed death-1 (PD-1) in suppressing MiHA-specific CD8(+) T cell immunity. In this study, we investigated whether B and T lymphocyte attenuator (BTLA) plays a similar role in functional impairment of MiHA-specific T cells after allo-SCT. In addition to PD-1, we observed higher BTLA expression on MiHA-specific CD8(+) T cells compared with that of the total population of CD8(+) effector-memory T cells. In addition, BTLA's ligand, herpes virus entry mediator (HVEM), was found constitutively expressed by myeloid leukemia, B cell lymphoma, and multiple myeloma cells. Interference with the BTLA-HVEM pathway, using a BTLA blocking Ab, augmented proliferation of BTLA(+)PD-1(+) MiHA-specific CD8(+) T cells by HVEM-expressing dendritic cells. Notably, we demonstrated that blocking of BTLA or PD-1 enhanced ex vivo proliferation of MiHA-specific CD8(+) T cells in respectively 7 and 9 of 11 allo-SCT patients. Notably, in 3 of 11 patients, the effect of BTLA blockade was more prominent than that of PD-1 blockade. Furthermore, these expanded MiHA-specific CD8(+) T cells competently produced effector cytokines and degranulated upon Ag reencounter. Together, these results demonstrate that BTLA-HVEM interactions impair MiHA-specific T cell functionality, providing a rationale for interfering with BTLA signaling in post-stem cell transplantation therapies.

Anesthetic effects changeable in habitual drinkers: Mechanistic drug interactions with neuro-active indoleamine-aldehyde condensation products associated with alcoholic beverage consumption.

PubMed

Tsuchiya, Hironori

2016-07-01

Clinicians often experience the reduced efficacy of general and local anesthetics and anesthesia-related drugs in habitual drinkers and chronic alcoholics. However, the mechanistic background underlying such anesthetic tolerance remains unclear. Biogenic indoleamines condense with alcohol-derived aldehydes during fermentation processes and under physiological conditions to produce neuro-active tetrahydro-β-carbolines and β-carbolines, many of which are contained not only in various alcoholic beverages but also in human tissues and body fluids. These indoleamine-aldehyde condensation products are increased in the human body because of their exogenous and endogenous supply enhanced by alcoholic beverage consumption. Since tetrahydro-β-carbolines and β-carbolines target receptors, ion channels and neuronal membranes which are common to anesthetic agents, we propose a hypothesis that they may pharmacodynamically interact at GABAA receptors, NMDA receptors, voltage-gated Na(+) channels and membrane lipid bilayers to attenuate anesthetics-induced positive allosteric GABAA receptor modulation, NMDA receptor antagonism, ion channel blockade and neuronal membrane modification, thereby affecting anesthetic efficacy. The condensation products may also cooperatively interact with ethanol that induces adaptive changes and cross-tolerance to anesthetics and with dopamine-aldehyde adducts that act on GABAA receptors and membrane lipids. Because tetrahydro-β-carbolines and β-carbolines are metabolized to lose or decrease their neuro-activities, induction of the relevant enzymes by habitual drinking could produce an inter-individual difference of drinkers in susceptibility to anesthetic agents. The present hypothesis would also provide a unified framework for different modes of anesthetic action, which are inhibited by neuro-active indoleamine-aldehyde condensation products associated with alcoholic beverage consumption. Copyright © 2016 Elsevier Ltd. All rights reserved.

Neurokinin-1 receptor activation in Botzinger complex evokes bradypnoea.

PubMed

Fong, Angelina Y; Potts, Jeffrey T

2006-09-15

In the present study, we examined the role of the neurokinin-1 receptor (NK1R) in the modulation of respiratory rhythm in a functionally identified bradypnoeic region of the ventral respiratory group (VRG) in the in situ arterially perfused juvenile rat preparation. In electrophysiologically and functionally identified bradypnoeic sites corresponding to the Bötzinger complex (BötC), microinjection of the selective NK1R agonist [Sar(9)-Met(O(2))(11)]-substance P (SSP) produced a significant reduction in phrenic frequency mediated exclusively by an increase in expiratory duration (T(E)). The reduction was characterized by a significant increase in postinspiratory (post-I) duration with no effect on either late-expiratory duration (E2) or inspiratory duration (T(I)). In contrast, in a functionally identified tachypnoeic region, corresponding to the preBötzinger complex (Pre-BötC), control microinjection of SSP elicited tachypnoea. Pretreatment with the NK1R antagonist CP99994 in the BötC significantly attenuated the bradypnoeic response to SSP injection and blunted the increase in T(E) duration. This effect of SSP mimicked the extension of T(E) produced by activation of the Hering-Breuer reflex. Therefore, we hypothesized that activation of NK1Rs in the BötC is requisite for the expiratory-lengthening effect of the Hering-Breuer reflex. Unilateral electrical stimulation of the cervical vagus nerve produced bradypnoea by exclusively extending T(E). Ipsilateral blockade of NK1Rs by CP99994 following blockade of the contralateral BötC by the GABA(A) receptor agonist muscimol significantly reduced the extension of T(E) produced by vagal stimulation. Results from the present study demonstrate that selective activation of NK1Rs in a functionally identified bradypnoeic region of the VRG can depress respiratory frequency by selectively lengthening post-I duration and provide evidence that endogenous activation of NK1Rs in the BötC appears to be involved in the expiratory-lengthening effect of the Hering-Breuer reflex. In conclusion, our findings demonstrate that selective activation of NK1Rs in discrete regions of the VRG can exert functionally diverse effects on breathing.

Dopamine Transporter Blockade Increases LTP in the CA1 Region of the Rat Hippocampus via Activation of the D3 Dopamine Receptor

ERIC Educational Resources Information Center

Swant, Jarod; Wagner, John J.

2006-01-01

Dopamine has been demonstrated to be involved in the modulation of long-term potentiation (LTP) in the CA1 region of the hippocampus. As monoamine transporter blockade will increase the actions of endogenous monoamine neurotransmitters, the effect of a dopamine transporter (DAT) antagonist on LTP was assessed using field excitatory postsynaptic…

Long-term systemic angiotensin II type 1 receptor blockade regulates mRNA expression of dorsomedial medulla renin-angiotensin system components

PubMed Central

Gilliam-Davis, Shea; Gallagher, Patricia E.; Payne, Valerie S.; Kasper, Sherry O.; Tommasi, Ellen N.; Westwood, Brian M.; Robbins, Michael E.; Chappell, Mark C.

2011-01-01

In Fischer 344 (F344) rats, renin-angiotensin system (RAS) blockade for 1 yr with the angiotensin II type 1 (AT1) receptor blocker L-158,809 prevents age-related impairments in metabolic function, similar to transgenic rats with low glial angiotensinogen (Aogen). Brain RAS regulation may contribute to the benefits of long-term systemic AT1 antagonism. We assessed the mRNA of RAS components in the dorsomedial medulla of F344 rats at 3 (young; n = 8) or 15 mo of age (old; n = 7) and in rats treated from 3 to 15 mo of age with 20 mg/l of the AT1 receptor antagonist L-158,809 (Old+L; n = 6). Aogen and renin mRNA were lower in the young compared with old group. Angiotensin-converting enzyme (ACE) mRNA was lower in the old and Old+L compared with the young group. ACE2 and neprilysin expression were significantly higher in Old+L compared with young or old rats. AT1b, AT2, and Mas receptor mRNA were higher with treatment. Leptin receptor mRNA was lower in the old rats and this was prevented by L-158,809 treatment. Dual-specificity phosphatase 1 (DUSP1) mRNA was highest in the Old+L group. Aggregate correlate summation revealed a positive relationship for Mas receptor mRNA with food intake. The findings provide evidence for regulation of dorsomedial medullary renin and Aogen mRNA during aging. Long-term AT1 receptor blockade increases the mRNA of the enzymes ACE2 and neprilysin and the MAS receptor, which could potentially shift the balance from ANG II to ANG-(1–7) and prevent age-related declines in the leptin receptor and its signaling pathway. PMID:21540301

The tuberal lateral hypothalamus is a major target for GABAA--but not GABAB-mediated control of food intake.

PubMed

Turenius, Christine I; Charles, Jonathan R; Tsai, Donna H; Ebersole, Priscilla L; Htut, Myat H; Ngo, Phuong T; Lara, Raul N; Stanley, B Glenn

2009-08-04

The lateral hypothalamus (LH) is a site of integration for control mechanisms of feeding behavior as it has extensive reciprocal connections with multiple intrahypothalamic and extrahypothalamic brain areas. Evidence suggests that blockade of ionotropric gamma-aminobutyric acid (GABA) receptors in the LH elicits eating in satiated rats. To determine whether this GABA(A) receptor antagonist effect is specific to the LH, the antagonist picrotoxin was injected into one of six nearby sites and food intake was measured. Picrotoxin at 133 pmol elicited eating in the LH, but not in surrounding sites (thalamus, lateral preoptic area, ventral tegmental area, dorsomedial hypothalamus, and entopeduncular nucleus). More specifically, picrotoxin injected into the tuberal LH (tLH) elicited eating, but was ineffective when injected into the anterior or posterior LH. We also investigated whether GABA(B) receptors in the LH participated in the control of food intake and found that neither blockade nor activation of these receptors under multiple conditions changed food intake. Collectively, our findings suggest that GABA(A) but not GABA(B) receptors in the tLH act to suppress feeding behavior.

AT1-receptor blockade, but not renin inhibition, reduces aneurysm growth and cardiac failure in fibulin-4 mice.

PubMed

Te Riet, Luuk; van Deel, Elza D; van Thiel, Bibi S; Moltzer, Els; van Vliet, Nicole; Ridwan, Yanto; van Veghel, Richard; van Heijningen, Paula M; Robertus, Jan Lukas; Garrelds, Ingrid M; Vermeij, Marcel; van der Pluijm, Ingrid; Danser, A H Jan; Essers, Jeroen

2016-04-01

Increasing evidence supports a role for the angiotensin II-AT1-receptor axis in aneurysm development. Here, we studied whether counteracting this axis via stimulation of AT2 receptors is beneficial. Such stimulation occurs naturally during AT1-receptor blockade with losartan, but not during renin inhibition with aliskiren. Aneurysmal homozygous fibulin-4 mice, displaying a four-fold reduced fibulin-4 expression, were treated with placebo, losartan, aliskiren, or the β-blocker propranolol from day 35 to 100. Their phenotype includes cystic media degeneration, aortic regurgitation, left ventricular dilation, reduced ejection fraction, and fractional shortening. Although losartan and aliskiren reduced hemodynamic stress and increased renin similarly, only losartan increased survival. Propranolol had no effect. No drug rescued elastic fiber fragmentation in established aneurysms, although losartan did reduce aneurysm size. Losartan also increased ejection fraction, decreased LV diameter, and reduced cardiac pSmad2 signaling. None of these effects were seen with aliskiren or propranolol. Longitudinal micro-CT measurements, a novel method in which each mouse serves as its own control, revealed that losartan reduced LV growth more than aneurysm growth, presumably because the heart profits both from the local (cardiac) effects of losartan and its effects on aortic root remodeling. Losartan, but not aliskiren or propranolol, improved survival in fibulin-4 mice. This most likely relates to its capacity to improve structure and function of both aorta and heart. The absence of this effect during aliskiren treatment, despite a similar degree of blood pressure reduction and renin-angiotensin system blockade, suggests that it might be because of AT2-receptor stimulation.

Pharmacological blockade of the cold receptor TRPM8 attenuates autonomic and behavioral cold defenses and decreases deep body temperature

PubMed Central

Almeida, M. Camila; Hew-Butler, Tamara; Soriano, Renato N.; Rao, Sara; Wang, Weiya; Wang, Judy; Tamayo, Nuria; Oliveira, Daniela L.; Nucci, Tatiane B.; Aryal, Prafulla; Garami, Andras; Bautista, Diana; Gavva, Narender R.; Romanovsky, Andrej A.

2012-01-01

We studied M8-B, a selective and potent antagonist of the transient receptor potential melastatin-8 (TRPM8) channel. In vitro, M8-B blocked cold-induced and TRPM8-agonist-induced activation of rat, human, and murine TRPM8 channels, including those on primary sensory neurons. In vivo, M8-B decreased deep body temperature (Tb) in Trpm8+/+ mice and rats, but not in Trpm8−/− mice, thus suggesting an on-target action. The intravenous administration of M8-B was more effective in decreasing Tb in rats than the intrathecal or intracerebroventricular administration, indicating a peripheral action. M8-B attenuated cold-induced c-Fos expression in the lateral parabrachial nucleus, thus indicating a site of action within the cutaneous cooling neural pathway to thermoeffectors, presumably on sensory neurons. A low intravenous dose of M8-B did not affect Tb at either a constantly high or a constantly low ambient temperature (Ta), but the same dose readily decreased Tb if rats were kept at a high Ta during the M8-B infusion and transferred to a low Ta immediately thereafter. These data suggest that both a successful delivery of M8-B to the skin (high cutaneous perfusion) and the activation of cutaneous TRPM8 channels (by cold) are required for the hypothermic action of M8-B. At tail skin temperatures < 23°C, the magnitude of the M8-B-induced decrease in Tb was inversely related to skin temperature, thus suggesting that M8-B blocks thermal (cold) activation of TRPM8. M8-B affected all thermoeffectors studied (thermopreferendum, tail skin vasoconstriction, and brown fat thermogenesis), thus suggesting that TRPM8 is a universal cold receptor in the thermoregulation system. PMID:22323721

Repeated 7-Day Treatment with the 5-HT2C Agonist Lorcaserin or the 5-HT2A Antagonist Pimavanserin Alone or in Combination Fails to Reduce Cocaine vs Food Choice in Male Rhesus Monkeys

PubMed Central

Banks, Matthew L; Negus, S Stevens

2017-01-01

Cocaine use disorder is a global public health problem for which there are no Food and Drug Administration-approved pharmacotherapies. Emerging preclinical evidence has implicated both serotonin (5-HT) 2C and 2A receptors as potential mechanisms for mediating serotonergic attenuation of cocaine abuse-related neurochemical and behavioral effects. Therefore, the present study aim was to determine whether repeated 7-day treatment with the 5-HT2C agonist lorcaserin (0.1–1.0 mg/kg per day, intramuscular; 0.032–0.1 mg/kg/h, intravenous) or the 5-HT2A inverse agonist/antagonist pimavanserin (0.32–10 mg/kg per day, intramuscular) attenuated cocaine reinforcement under a concurrent ‘choice’ schedule of cocaine and food availability in rhesus monkeys. During saline treatment, cocaine maintained a dose-dependent increase in cocaine vs food choice. Repeated pimavanserin (3.2 mg/kg per day) treatments significantly increased small unit cocaine dose choice. Larger lorcaserin (1.0 mg/kg per day and 0.1 mg/kg/h) and pimavanserin (10 mg/kg per day) doses primarily decreased rates of operant behavior. Coadministration of ineffective lorcaserin (0.1 mg/kg per day) and pimavanserin (0.32 mg/kg per day) doses also failed to significantly alter cocaine choice. These results suggest that neither 5-HT2C receptor activation nor 5-HT2A receptor blockade are sufficient to produce a therapeutic-like decrease in cocaine choice and a complementary increase in food choice. Overall, these results do not support the clinical utility of 5-HT2C agonists and 5-HT2A inverse agonists/antagonists alone or in combination as candidate anti-cocaine use disorder pharmacotherapies. PMID:27857126

Repeated 7-Day Treatment with the 5-HT2C Agonist Lorcaserin or the 5-HT2A Antagonist Pimavanserin Alone or in Combination Fails to Reduce Cocaine vs Food Choice in Male Rhesus Monkeys.

PubMed

Banks, Matthew L; Negus, S Stevens

2017-04-01

Cocaine use disorder is a global public health problem for which there are no Food and Drug Administration-approved pharmacotherapies. Emerging preclinical evidence has implicated both serotonin (5-HT) 2C and 2A receptors as potential mechanisms for mediating serotonergic attenuation of cocaine abuse-related neurochemical and behavioral effects. Therefore, the present study aim was to determine whether repeated 7-day treatment with the 5-HT 2C agonist lorcaserin (0.1-1.0 mg/kg per day, intramuscular; 0.032-0.1 mg/kg/h, intravenous) or the 5-HT 2A inverse agonist/antagonist pimavanserin (0.32-10 mg/kg per day, intramuscular) attenuated cocaine reinforcement under a concurrent 'choice' schedule of cocaine and food availability in rhesus monkeys. During saline treatment, cocaine maintained a dose-dependent increase in cocaine vs food choice. Repeated pimavanserin (3.2 mg/kg per day) treatments significantly increased small unit cocaine dose choice. Larger lorcaserin (1.0 mg/kg per day and 0.1 mg/kg/h) and pimavanserin (10 mg/kg per day) doses primarily decreased rates of operant behavior. Coadministration of ineffective lorcaserin (0.1 mg/kg per day) and pimavanserin (0.32 mg/kg per day) doses also failed to significantly alter cocaine choice. These results suggest that neither 5-HT 2C receptor activation nor 5-HT 2A receptor blockade are sufficient to produce a therapeutic-like decrease in cocaine choice and a complementary increase in food choice. Overall, these results do not support the clinical utility of 5-HT 2C agonists and 5-HT 2A inverse agonists/antagonists alone or in combination as candidate anti-cocaine use disorder pharmacotherapies.

Mu-opioid blockade reduces ethanol effects on intake and behavior of the infant rat during short-term but not long-term social isolation

PubMed Central

Kozlov, Andrey P.; Nizhnikov, Michael E.; Kramskaya, Tatiana. A.; Varlinskaya, Elena I.; Spear, Norman E.

2013-01-01

Numerous findings in adult and infant rats have shown that the endogenous opioid system is involved in control of ethanol consumption and its reinforcing effects. Opioid systems are also involved in reactivity to social isolation with several factors (age, duration, and type of isolation) affecting this modulation. The present study investigated the effects of a selective mu – opioid antagonist CTOP (0, 0.1, 0.5 mg/kg), ethanol (0, 0.5 g/kg), and the interaction of the two drugs on the behavioral consequences of two types of social isolation given to preweanling rats: 1) short–term social isolation from littermates (STSI, duration 8 minutes) and 2) relatively long-term (5 hours) isolation (LTSI) from the dam and littermates. Voluntary intake of saccharin, locomotion, rearing activity, paw licking, and grooming were assessed during an 8 – min. intake test. Thermal nociceptive reactivity was also measured before and after the testing session with normalized differences in pre- and post-test latencies of paw withdrawal from a hot plate (49 °C) used as an index of isolation-induced analgesia (IIA). The results indicate that pharmacological blockade of mu-opioid receptors by CTOP substantially attenuated ethanol’s anxiolytic effects on the developing rat’s reactions to social isolation. Some of these stress-attenuating effects of CTOP were observed only in animals exposed to short-term isolation (STSI) but not in pups isolated for 5 hours (LTSI). Ethanol selectively increased saccharin intake during STSI in females and CTOP blocked this effect. Ethanol decreased the magnitude of analgesia associated with STSI but had no effect on pain reactivity during LTSI. CTOP by itself did not affect IIA or saccharin intake in sober animals. The findings of the present experiments indicate that the anxiolytic effects of 0.5 g/kg ethanol on pups exposed to STSI are modulated by endogenous opioid activity. PMID:23182856

Foot orgasm syndrome: a case report in a woman.

PubMed

Waldinger, Marcel D; de Lint, Govert J; van Gils, Ad P G; Masir, Farhad; Lakke, Egbert; van Coevorden, Ruben S; Schweitzer, Dave H

2013-08-01

Spontaneous orgasm triggered from inside the foot has so far not been reported in medical literature. The study aims to report orgasmic feelings in the left foot of a woman. A woman presented with complaints of undesired orgasmic sensations originating in her left foot. In-depth interview, physical examination, sensory testing, magnetic resonance imaging (MRI-scan), electromyography (EMG), transcutaneous electrical nerve stimulation (TENS), and blockade of the left S1 dorsal root ganglion were performed. The main outcomes are description of this clinical syndrome, results of TENS application, and S1 dorsal root ganglion blockade. Subtle attenuation of sensory amplitudes of the left suralis, and the left medial and lateral plantar nerve tracts was found at EMG. MRI-scan disclosed no foot abnormalities. TENS at the left metatarso-phalangeal joint-III of the left foot elicited an instant orgasmic sensation that radiated from plantar toward the vagina. TENS applied to the left side of the vagina elicited an orgasm that radiated to the left foot. Diagnostic blockade of the left S1 dorsal root ganglion with 0.8 mL bupivacaine 0.25 mg attenuated the frequency and intensity of orgasmic sensation in the left foot with 50% and 80%, respectively. Additional therapeutic blockade of the same ganglion with 0.8 mL bupivacaine 0.50 mg combined with pulsed radiofrequency treatment resulted in a complete disappearance of the foot-induced orgasmic sensations. Foot orgasm syndrome (FOS) is descibed in a woman. Blockade of the left S1 dorsal root ganglion alleviated FOS. It is hypothesized that FOS, occurring 1.5 years after an intensive care emergency, was caused by partial nerve regeneration (axonotmesis), after which afferent (C-fiber) information from a small reinnervated skin area of the left foot and afferent somatic and autonomous (visceral) information from the vagina on at least S1 spinal level is misinterpreted by the brain as being solely information originating from the vagina. © 2013 International Society for Sexual Medicine.

Characterization of methadone as a β-arrestin-biased μ-opioid receptor agonist

PubMed Central

Doi, Seira; Mori, Tomohisa; Uzawa, Naoki; Arima, Takamichi; Takahashi, Tomoyuki; Uchida, Masashi; Yawata, Ayaka; Narita, Michiko; Uezono, Yasuhito; Suzuki, Tsutomu

2016-01-01

Background Methadone is a unique µ-opioid receptor agonist. Although several researchers have insisted that the pharmacological effects of methadone are mediated through the blockade of NMDA receptor, the underlying mechanism by which methadone exerts its distinct pharmacological effects compared to those of other µ-opioid receptor agonists is still controversial. In the present study, we further investigated the pharmacological profile of methadone compared to those of fentanyl and morphine as measured mainly by the discriminative stimulus effect and in vitro assays for NMDA receptor binding, µ-opioid receptor-internalization, and µ-opioid receptor-mediated β-arrestin recruitment. Results We found that fentanyl substituted for the discriminative stimulus effects of methadone, whereas a relatively high dose of morphine was required to substitute for the discriminative stimulus effects of methadone in rats. Under these conditions, the non-competitive NMDA receptor antagonist MK-801 did not substitute for the discriminative stimulus effects of methadone. In association with its discriminative stimulus effect, methadone failed to displace the receptor binding of MK801 using mouse brain membrane. Methadone and fentanyl, but not morphine, induced potent µ-opioid receptor internalization accompanied by the strong recruitment of β-arrestin-2 in µ-opioid receptor-overexpressing cells. Conclusions These results suggest that methadone may, at least partly, produce its pharmacological effect as a β-arrestin-biased µ-opioid receptor agonist, similar to fentanyl, and NMDA receptor blockade is not the main contributor to the pharmacological profile of methadone. PMID:27317580

NMDA Receptors Subserve Persistent Neuronal Firing During Working Memory In Dorsolateral Prefrontal Cortex

PubMed Central

Wang, Min; Yang, Yang; Wang, Ching-Jung; Gamo, Nao J.; Jin, Lu E.; Mazer, James A.; Morrison, John H.; Wang, Xiao-Jing; Arnsten, Amy F.T.

2013-01-01

Summary Neurons in the primate dorsolateral prefrontal cortex (dlPFC) generate persistent firing in the absence of sensory stimulation, the foundation of mental representation. Persistent firing arises from recurrent excitation within a network of pyramidal Delay cells. Here, we examined glutamate receptor influences underlying persistent firing in primate dlPFC during a spatial working memory task. Computational models predicted dependence on NMDA receptor (NMDAR) NR2B stimulation, and Delay cell persistent firing was abolished by local NR2B NMDAR blockade or by systemic ketamine administration. AMPA receptors (AMPAR) contributed background depolarization to sustain network firing. In contrast, many Response cells -which likely predominate in rodent PFC- were sensitive to AMPAR blockade and increased firing following systemic ketamine, indicating that models of ketamine actions should be refined to reflect neuronal heterogeneity. The reliance of Delay cells on NMDAR may explain why insults to NMDARs in schizophrenia or Alzheimer’s Disease profoundly impair cognition. PMID:23439125

The role of excitatory amino acids and substance P in the mediation of the cough reflex within the nucleus tractus solitarii of the rabbit.

PubMed

Mutolo, Donatella; Bongianni, Fulvia; Fontana, Giovanni A; Pantaleo, Tito

2007-09-28

We hypothesized that cough evoked by mechanical stimulation of the tracheobronchial tree in the rabbit is primarily mediated by glutamatergic neurotransmission at the level of the caudal portions of the medial subnucleus of the nucleus tractus solitarii (NTS) and the lateral commissural NTS where cough-related afferents terminate, and that this reflex is potentiated by local release of substance P. To test our hypothesis, we performed bilateral microinjections (30-50 nl) of ionotropic glutamate receptor antagonists or substance P into these locations in pentobarbitone anaesthetized, spontaneously breathing rabbits. Blockade of NMDA and non-NMDA receptors by 50mM kynurenic acid abolished the cough reflex without affecting the Breuer-Hering inflation reflex or the pulmonary chemoreflex. Blockade of non-NMDA receptors using 10mM CNQX or 5mM NBQX caused identical effects. Blockade of NMDA receptors by 10mM D-AP5 strongly reduced, but did not abolish cough responses. Microinjections of 1mM substance P increased peak and rate of rise of abdominal muscle activity as well as cough number. These results are the first to provide evidence that ionotropic glutamate receptors, especially non-NMDA receptors, located within specific regions of NTS are primarily involved in the mediation of cough evoked by mechanical stimulation of the tracheobronchial tree in the rabbit. Present findings on substance P cough-enhancing effects extend previous observations and are relevant to the tachykinin-mediated central sensitization of the cough reflex. They also may provide hints for further studies on centrally acting antitussive drugs.

Role of AMPA glutamate receptors in the conditioned rewarding effects of MDMA in mice.

PubMed

García-Pardo, M P; Miñarro, J; Aguilar, M A

2018-07-16

Currently, there is not an effective treatment for 3,4-methylenedioxymethamphetamine (MDMA) dependence but pharmacotherapies targeting glutamate neurotransmission are a promising strategy. Previously, we showed that blockade of glutamate NMDA and AMPA receptors impairs the conditioned rewarding effects of MDMA and cocaine, respectively. In this study we evaluated the role of AMPA receptors in the rewarding effects of MDMA in mice using the conditioned place preference (CPP) paradigm. Mice were conditioned with MDMA (1.25 mg/kg) 60 min after the treatment with saline or different doses (0.25, 1 and 5 mg/kg) of the AMPA/kainate receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). Mice conditioned with MDMA acquired CPP while those treated with any dose of CNQX + MDMA did not. These results supported the involvement of the glutamatergic system in the rewarding properties of MDMA, and suggest that AMPA receptor blockade could be a new therapeutic option for the treatment of those individuals that develop MDMA dependence. Copyright © 2018 Elsevier B.V. All rights reserved.

The role of dopamine receptors in the neurotoxicity of methamphetamine.

PubMed

Ares-Santos, S; Granado, N; Moratalla, R

2013-05-01

Methamphetamine is a synthetic drug consumed by millions of users despite its neurotoxic effects in the brain, leading to loss of dopaminergic fibres and cell bodies. Moreover, clinical reports suggest that methamphetamine abusers are predisposed to Parkinson's disease. Therefore, it is important to elucidate the mechanisms involved in methamphetamine-induced neurotoxicity. Dopamine receptors may be a plausible target to prevent this neurotoxicity. Genetic inactivation of dopamine D1 or D2 receptors protects against the loss of dopaminergic fibres in the striatum and loss of dopaminergic neurons in the substantia nigra. Protection by D1 receptor inactivation is due to blockade of hypothermia, reduced dopamine content and turnover and increased stored vesicular dopamine in D1R(-/-) mice. However, the neuroprotective impact of D2 receptor inactivation is partially dependent on an effect on body temperature, as well as on the blockade of dopamine reuptake by decreased dopamine transporter activity, which results in reduced intracytosolic dopamine levels in D2R(-/-) mice. © 2013 The Association for the Publication of the Journal of Internal Medicine.

Biological effects of blocking blue and other visible light on the mouse retina.

PubMed

Narimatsu, Toshio; Ozawa, Yoko; Miyake, Seiji; Kubota, Shunsuke; Yuki, Kenya; Nagai, Norihiro; Tsubota, Kazuo

2014-08-01

To elucidate the biological effects of blocking fluorescent light on the retina using specific blocking materials. Seven- to 8-week-old BALB/c mice were divided into three groups and placed in one of the three boxes: one blocked ultraviolet and violet wavelengths of light (violet blockade), one blocked ultraviolet, violet, blue and some other visible wavelengths (blue-plus blockade), and one allowed most visible light to pass through (control). They were then exposed to a white fluorescent lamp for 1 h at 5.65E-05 mW/cm(2) /s. After treatment, the electroretinogram, retinal outer nuclear layer thickness and retinal outer segment length were measured. In addition, retinal apoptotic cells were quantified by TdT-mediated dUTP nick-end labelling assay and c-Fos messenger RNA, and protein levels were measured by real-time reverse-transcription polymerase chain reaction and immunoblot analyses, respectively. The blue-plus blockade group retained a significantly better electroretinogram response following light exposure than the control or violet blockade groups. The blue-plus blockade group also exhibited greater outer nuclear layer thickness and greater outer-segment length, and fewer apoptotic cells after light exposure than the other groups. The c-Fos messenger RNA and protein levels were substantially reduced in the blue-plus blockade group and reduced to a lesser extent in the violet blockade group. The blockade of blue plus additional visible wavelengths of light was most effective in protecting the retina from light-induced damage. The blockade of violet light alone was also effective in reducing intracellular molecular responses, but these effects were not sufficient for attenuating retinal degeneration. © 2013 Royal Australian and New Zealand College of Ophthalmologists.

Astrocyte-derived interleukin-15 exacerbates ischemic brain injury via propagation of cellular immunity.

PubMed

Li, Minshu; Li, Zhiguo; Yao, Yang; Jin, Wei-Na; Wood, Kristofer; Liu, Qiang; Shi, Fu-Dong; Hao, Junwei

2017-01-17

Astrocytes are believed to bridge interactions between infiltrating lymphocytes and neurons during brain ischemia, but the mechanisms for this action are poorly understood. Here we found that interleukin-15 (IL-15) is dramatically up-regulated in astrocytes of postmortem brain tissues from patients with ischemic stroke and in a mouse model of transient focal brain ischemia. We generated a glial fibrillary acidic protein (GFAP) promoter-controlled IL-15-expressing transgenic mouse (GFAP-IL-15 tg ) line and found enlarged brain infarcts, exacerbated neurodeficits after the induction of brain ischemia. In addition, knockdown of IL-15 in astrocytes attenuated ischemic brain injury. Interestingly, the accumulation of CD8 + T and natural killer (NK) cells was augmented in these GFAP-IL-15 tg mice after brain ischemia. Of note, depletion of CD8 + T or NK cells attenuated ischemic brain injury in GFAP-IL-15 tg mice. Furthermore, knockdown of the IL-15 receptor α or blockade of cell-to-cell contact diminished the activation and effector function of CD8 + T and NK cells in GFAP-IL-15 tg mice, suggesting that astrocytic IL-15 is delivered in trans to target cells. Collectively, these findings indicate that astrocytic IL-15 could aggravate postischemic brain damage via propagation of CD8 + T and NK cell-mediated immunity.

Effects of calcium channel blockers comparing to angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in patients with hypertension and chronic kidney disease stage 3 to 5 and dialysis: A systematic review and meta-analysis

PubMed Central

Lin, Yen-Chung; Lin, Jheng-Wei; Wu, Mai-Szu; Chen, Kuan-Chou; Peng, Chiung-Chi

2017-01-01

Background Calcium channel blocker (CCB) or two renin angiotensin aldosterone system blockades (RAAS), angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), are major potent and prevalently used as initial antihypertensive agents for mild to moderate hypertension, but no uniform agreement as to which antihypertensive drugs should be given for initial therapy, especially among chronic kidney disease (CKD) patients. Design A systematic review and meta-analysis comparing CCBs and the two RAAS blockades for hypertensive patients with CKD stage 3 to 5D. The inclusion criteria for this systematic review was RCT that compared the effects of CCBs and the two RAAS blockades in patients with hypertension and CKD. The exclusion criteria were (1) renal transplantation, (2) CKD stage 1 or 2, (3) combined therapy (data cannot be extracted separately). Outcomes were blood pressure change, mortality, heart failure, stroke or cerebrovascular events, and renal outcomes. Results 21 randomized controlled trials randomized 9,492 patients with hypertensive and CKD into CCBs and the two RAAS blockades treatments. The evidence showed no significant differences in blood presser change, mortality, heart failure, stroke or cerebrovascular events, and renal outcomes between CCBs group and the two RAAS blockades group. The publication bias of pooled mean blood presser change that was detected by Egger’s test was non-significant. Conclusions CCBs has similar effects on long term blood pressure, mortality, heart failure, stroke or cerebrovascular events, and renal function to RAAS blockades in patients CKD stage 3 to 5D and hypertension. PMID:29240784

Beta Ca2+/CaM-dependent kinase type II triggers upregulation of GluA1 to coordinate adaptation to synaptic inactivity in hippocampal neurons.

PubMed

Groth, Rachel D; Lindskog, Maria; Thiagarajan, Tara C; Li, Li; Tsien, Richard W

2011-01-11

Prolonged AMPA-receptor blockade in hippocampal neuron cultures leads to both an increased expression of GluA1 postsynaptically and an increase in vesicle pool size and turnover rate presynaptically, adaptive changes that extend beyond simple synaptic scaling. As a molecular correlate, expression of the β Ca(2+)/CaM-dependent kinase type II (βCaMKII) is increased in response to synaptic inactivity. Here we set out to clarify the role of βCaMKII in the various manifestations of adaptation. Knockdown of βCaMKII by lentiviral-mediated expression of shRNA prevented the synaptic inactivity-induced increase in GluA1, as did treatment with the CaM kinase inhibitor KN-93, but not the inactive analog KN-92. These results demonstrate that, spurred by AMPA-receptor blockade, up-regulation of βCaMKII promotes increased GluA1 expression. Indeed, transfection of βCaMKII, but not a kinase-dead mutant, increased GluA1 expression on dendrites and elevated vesicle turnover (Syt-Ab uptake), mimicking the effect of synaptic inactivity on both sides of the synapse. In cells with elevated βCaMKII, relief of synaptic-activity blockade uncovered an increase in the frequency of miniature excitatory postsynaptic currents that could be rapidly and fully suppressed by PhTx blockade of GluA1 receptors. This increased mini frequency involved a genuine presynaptic enhancement, not merely an increased abundance of synapses. This finding suggests that Ca(2+) flux through GluA1 receptors may trigger the acute release of a retrograde messenger. Taken together, our results indicate that synaptic inactivity-induced increases in βCaMKII expression set in motion a series of events that culminate in coordinated pre- and postsynaptic adaptations in synaptic transmission.

Myogenic constriction is increased in mesenteric resistance arteries from rats with chronic heart failure: instantaneous counteraction by acute AT1 receptor blockade

PubMed Central

Gschwend, S; Henning, R H; Pinto, Y M; de Zeeuw, D; van Gilst, W H; Buikema, H

2003-01-01

Increased vascular resistance in chronic heart failure (CHF) has been attributed to stimulated neurohumoral systems. However, local mechanisms may also importantly contribute to set arterial tone. Our aim, therefore, was to test whether pressure-induced myogenic constriction of resistance arteries in vitro – devoid of acute effects of circulating factors – is increased in CHF and to explore underlying mechanisms. At 12 weeks after coronary ligation-induced myocardial infarction or SHAM-operations in rats, we studied isolated mesenteric arteries for myogenic constriction, determined as the active constriction (% of passive diameter) in response to stepwise increase in intraluminal pressure (20 – 160 mmHg), in the absence and presence of inhibitors of potentially involved modulators of myogenic constriction. We found that myogenic constriction in mesenteric arteries from CHF rats was markedly increased compared to SHAM over the whole pressure range, the difference being most pronounced at 60 mmHg (24±2 versus 4±3%, respectively, P<0.001). Both removal of the endothelium as well as inhibition of NO production (L-NG-monomethylarginine, 100 μM) significantly increased myogenic constriction (+16 and +25%, respectively), the increase being similar in CHF- and SHAM-arteries (P=NS). Neither endothelin type A (ETA)-receptor blockade (BQ123, 1 μM) nor inhibition of perivascular (sympathetic) nerve conduction (tetrodotoxin, 100 nM) affected the myogenic response in either group. Interestingly, increased myogenic constriction in CHF was fully reversed after angiotensin II type I (AT1)-receptor blockade (candesartan, 100 nM; losartan, 10 μM), which was without effect in SHAM. In contrast, neither angiotensin-converting enzyme (ACE) inhibition (lisinopril, 1 μM; captopril, 10 μM) or AT2-receptor blockade (PD123319, 1 μM), nor inhibition of superoxide production (superoxide dismutase, 50 U ml−1), TXA2-receptor blockade (SQ29,548, 1 μM) or inhibition of cyclooxygenase-derived prostaglandins (indomethacin, 10 μM) affected myogenic constriction. Sensitivity of mesenteric arteries to angiotensin II (10 nM – 100 μM) was increased (P<0.05) in CHF (pD2 7.1±0.4) compared to SHAM (pD2 6.2±0.3), while the sensitivity to KCl and phenylephrine was not different. Our results demonstrate increased myogenic constriction in small mesenteric arteries of rats with CHF, potentially making it an important target for therapy in counteracting increased vascular resistance in CHF. Our results further suggest active and instantaneous participation of AT1-receptors in increased myogenic constriction in CHF, involving increased sensitivity of AT1-receptors rather than apparent ACE-mediated local angiotensin II production. PMID:12890711

Differential control of collagen synthesis by the sympathetic and renin-angiotensin systems in the rat left ventricle.

PubMed

Dab, Houcine; Hachani, Rafik; Hodroj, Wassim; Sakly, Mohsen; Bricca, Giampiero; Kacem, Kamel

2009-12-03

In the present study, we tested the hypothesis of the indirect (via the sympathetic nervous system (SNS)) and direct (via AT1 receptors) contributions of Angiotensin II (Ang II) on the synthesis of collagen types I and III in the left ventricle (LV) in vivo. Sympathectomy and blockade of the Ang II receptor AT1 were performed alone or in combination in normotensive rats. The mRNA and protein synthesis of collagen types I and III were examined by Q-RT-PCR and immunoblotting in the LV. Collagen types I and III mRNA were decreased respectively by 53% and 22% after sympathectomy and only collagen type I mRNA was increased by 52% after AT1 receptor blockade. mRNA was not changed for collagen type I but was decreased by 25% for collagen type III after double treatment. Only collagen protein type III was decreased after sympathectomy by 12%, but collagen proteins were increased respectively for types I and III by 145% and 52% after AT1 receptor blockade and by 45% and 60% after double treatment. Deducted interpretations from our experimental approach suggest that Ang II stimulates indirectly (via SNS) and inhibits directly (via AT1 receptors) the collagen type I at transcriptional and protein levels. For collagen type III, it stimulates indirectly the transcription and inhibited directly the protein level. Therefore, the Ang II regulates collagen synthesis differently through indirect and direct pathways.

Indirect androgen doping by oestrogen blockade in sports

PubMed Central

Handelsman, D J

2008-01-01

Androgens can increase muscular mass and strength and remain the most frequently abused and widely available drugs used in sports doping. Banning the administration of natural or synthetic androgens has led to a variety of strategies to circumvent the ban of the most effective ergogenic agents for power sports. Among these, a variety of indirect androgen doping strategies aiming to produce a sustained rise in endogenous testosterone have been utilized. These include oestrogen blockade by drugs that act as oestrogen receptor antagonists (antioestrogen) or aromatase inhibitors. The physiological and pharmacological basis for the effects of oestrogen blockade in men, but not women, are reviewed. PMID:18500381

Early-Onset Network Hyperexcitability in Presymptomatic Alzheimer’s Disease Transgenic Mice Is Suppressed by Passive Immunization with Anti-Human APP/Aβ Antibody and by mGluR5 Blockade

PubMed Central

Kazim, Syed F.; Chuang, Shih-Chieh; Zhao, Wangfa; Wong, Robert K. S.; Bianchi, Riccardo; Iqbal, Khalid

2017-01-01

Cortical and hippocampal network hyperexcitability appears to be an early event in Alzheimer’s disease (AD) pathogenesis, and may contribute to memory impairment. It remains unclear if network hyperexcitability precedes memory impairment in mouse models of AD and what are the underlying cellular mechanisms. We thus evaluated seizure susceptibility and hippocampal network hyperexcitability at ~3 weeks of age [prior to amyloid beta (Aβ) plaque deposition, neurofibrillary pathology, and cognitive impairment] in a triple transgenic mouse model of familial AD (3xTg-AD mouse) that harbors mutated human Aβ precursor protein (APP), tau and presenilin 1 (PS1) genes. Audiogenic seizures were elicited in a higher proportion of 3xTg-AD mice compared with wild type (WT) controls. Seizure susceptibility in 3xTg-AD mice was attenuated either by passive immunization with anti-human APP/Aβ antibody (6E10) or by blockade of metabotropic glutamate receptor 5 (mGluR5) with the selective antagonist, 2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP). In in vitro hippocampal slices, suppression of synaptic inhibition with the GABAA receptor antagonist, bicuculline, induced prolonged epileptiform (>1.5 s in duration) ictal-like discharges in the CA3 neuronal network in the majority of the slices from 3xTg-AD mice. In contrast, only short epileptiform (<1.5 s in duration) interictal-like discharges were observed following bicuculline application in the CA3 region of WT slices. The ictal-like activity in CA3 region of the hippocampus was significantly reduced in the 6E10-immunized compared to the saline-treated 3xTg-AD mice. MPEP acutely suppressed the ictal-like discharges in 3xTg-AD slices. Remarkably, epileptiform discharge duration positively correlated with intraneuronal human (transgenic) APP/Aβ expression in the CA3 region of the hippocampus. Our data suggest that in a mouse model of familial AD, hypersynchronous network activity underlying seizure susceptibility precedes Aβ plaque pathology and memory impairment. This early-onset network hyperexcitability can be suppressed by passive immunization with an anti-human APP/Aβ antibody and by mGluR5 blockade in 3xTg-AD mice. PMID:28392767

Processing cardiovascular information in the vlPAG during electroacupuncture in rats: roles of endocannabinoids and GABA

PubMed Central

Tjen-A-Looi, Stephanie C.; Li, Peng; Longhurst, John C.

2009-01-01

A long-loop pathway, involving the hypothalamic arcuate nucleus (ARC), ventrolateral periaqueductal gray (vlPAG), and the rostral ventrolateral medulla (rVLM), is essential in electroacupuncture (EA) attenuation of sympathoexcitatory cardiovascular reflex responses. The ARC provides excitatory input to the vlPAG, which, in turn, inhibits neuronal activity in the rVLM. Although previous studies have shown that endocannabinoid CB1 receptor activation modulates γ-aminobutyric acid (GABA)-ergic and glutamatergic neurotransmission in the dorsolateral PAG in stress-induced analgesia, an important role for endocannabinoids in the vlPAG has not yet been observed. We recently have shown (Fu LW, Longhurst JC. J Appl Physiol; doi:10.1152/japplphysiol.91648.2008) that EA reduces the local vlPAG concentration of GABA, but not glutamate, as measured with high-performance liquid chromatography from extracellular samples collected by microdialysis. We, therefore, hypothesized that, during EA, endocannabinoids, acting through CB1 receptors, presynaptically inhibit GABA release to disinhibit the vlPAG and ultimately modulate excitatory reflex blood pressure responses. Rats were anesthetized, ventilated, and instrumented to measure heart rate and blood pressure. Gastric distention-induced blood pressure responses of 18 ± 5 mmHg were reduced to 6 ± 1 mmHg by 30 min of low-current, low-frequency EA applied bilaterally at pericardial P 5–6 acupoints overlying the median nerves. Like EA, microinjection of the fatty acid amide hydrolase inhibitor URB597 (0.1 nmol, 50 nl) into the vlPAG to increase endocannabinoids locally reduced the gastric distention cardiovascular reflex response from 21 ± 5 to 3 ± 4 mmHg. This inhibition was reversed by pretreatment with the GABAA antagonist gabazine (27 mM, 50 nl), suggesting that endocannabinoids exert their action through a GABAergic receptor mechanism in the vlPAG. The EA-related inhibition from 18 ± 3 to 8 ± 2 mmHg was reversed to 14 ± 2 mmHg by microinjection of the CB1 receptor antagonist AM251 (2 nmol, 50 nl) into the vlPAG. Pretreatment with gabazine eliminated reversal following CB1-receptor blockade. Thus EA releases endocannabinoids and activates presynaptic CB1 receptors to inhibit GABA release in the vlPAG. Reduction of GABA release disinhibits vlPAG cells, which, in turn, modulate the activity of rVLM neurons to attenuate the sympathoexcitatory reflex responses. PMID:19325030

Comparative effects of valsartan in combination with cilnidipine or amlodipine on cardiac remodeling and diastolic dysfunction in Dahl salt-sensitive rats.

PubMed

Nagasawa, Kai; Takahashi, Keiji; Matsuura, Natsumi; Takatsu, Miwa; Hattori, Takuya; Watanabe, Shogo; Harada, Eri; Niinuma, Kazumi; Murohara, Toyoaki; Nagata, Kohzo

2015-01-01

Angiotensin receptor blockers (ARBs) are often supplemented with calcium channel blockers (CCBs) for treatment of hypertension. We recently showed that the L/N-type CCB cilnidipine has superior cardioprotective effects compared with the L-type CCB amlodipine in Dahl salt-sensitive (DS) rats. We have now compared the effects of the ARB valsartan combined with cilnidipine or amlodipine on cardiac pathophysiology in DS rats. DS rats fed a high-salt diet from 6 weeks of age were treated with vehicle, valsartan alone (10 mg kg(-1) per day), or valsartan combined with either cilnidipine (1 mg kg(-1) per day) or amlodipine (1 mg kg(-1) per day) from 7 to 11 weeks. The salt-induced increase in systolic blood pressure apparent in the vehicle group was attenuated similarly in the three drug treatment groups. Valsartan-cilnidipine attenuated left ventricular (LV) fibrosis and diastolic dysfunction as well as cardiac oxidative stress and inflammation to a greater extent than did valsartan alone or valsartan-amlodipine. In addition, the increases in urinary excretion of dopamine and epinephrine as well as in cardiac renin-angiotensin-aldosterone-system (RAAS) gene expression apparent in vehicle-treated rats were attenuated to a greater extent by valsartan-cilnidipine than by the other two treatments. Valsartan-cilnidipine thus attenuated LV remodeling and diastolic dysfunction more effectively than did valsartan or valsartan-amlodipine in rats with salt-sensitive hypertension, and this superior cardioprotective action of valsartan-cilnidipine compared with valsartan-amlodipine is likely attributable, at least in part, to the greater antioxidant and antiinflammatory effects associated with both greater inhibition of cardiac RAAS gene expression and N-type calcium channel blockade.

IL-7 receptor blockade following T cell depletion promotes long-term allograft survival

PubMed Central

Mai, Hoa-Le; Boeffard, Françoise; Longis, Julie; Danger, Richard; Martinet, Bernard; Haspot, Fabienne; Vanhove, Bernard; Brouard, Sophie; Soulillou, Jean-Paul

2014-01-01

T cell depletion is commonly used in organ transplantation for immunosuppression; however, a restoration of T cell homeostasis following depletion leads to increased memory T cells, which may promote transplant rejection. The cytokine IL-7 is important for controlling lymphopoiesis under both normal and lymphopenic conditions. Here, we investigated whether blocking IL-7 signaling with a mAb that targets IL-7 receptor α (IL-7Rα) alone or following T cell depletion confers an advantage for allograft survival in murine transplant models. We found that IL-7R blockade alone induced indefinite pancreatic islet allograft survival if anti–IL-7R treatment was started 3 weeks before graft. IL-7R blockade following anti-CD4– and anti-CD8–mediated T cell depletion markedly prolonged skin allograft survival. Furthermore, IL-7 inhibition in combination with T cell depletion synergized with either CTLA-4Ig administration or suboptimal doses of tacrolimus to induce long-term skin graft acceptance in this stringent transplant model. Together, these therapies inhibited T cell reconstitution, decreased memory T cell numbers, increased the relative frequency of Tregs, and abrogated both cellular and humoral alloimmune responses. Our data suggest that IL-7R blockade following T cell depletion has potential as a robust, immunosuppressive therapy in transplantation. PMID:24569454

The effect of endothelin A and B receptor blockade on cutaneous vascular and sweating responses in young men during and following exercise in the heat.

PubMed

Fujii, Naoto; Singh, Maya S; Halili, Lyra; Louie, Jeffrey C; Kenny, Glen P

2016-12-01

During exercise, cutaneous vasodilation and sweating responses occur, whereas these responses rapidly decrease during postexercise recovery. We hypothesized that the activation of endothelin A (ET A ) receptors, but not endothelin B (ET B ) receptors, attenuate cutaneous vasodilation during high-intensity exercise and contribute to the subsequent postexercise suppression of cutaneous vasodilation. We also hypothesized that both receptors increase sweating during and following high-intensity exercise. Eleven men (24 ± 4 yr) performed an intermittent cycling protocol consisting of two 30-min bouts of moderate- (40% V̇o 2peak ) and high-intensity (75% V̇o 2peak ) exercise in the heat (35°C), each separated by a 20- and 40-min recovery period, respectively. Cutaneous vascular conductance (CVC) and sweat rate were evaluated at four intradermal microdialysis skin sites: 1) lactated Ringer (control), 2) 500 nM BQ123 (a selective ET A receptor blocker), 3) 300 nM BQ788 (a selective ET B receptor blocker), or 4) a combination of BQ123 + BQ788. There were no between-site differences in CVC during each exercise bout (all P > 0.05); however, CVC following high-intensity exercise was greater at BQ123 (56 ± 9%max) and BQ123 + BQ788 (55 ± 14%max) sites relative to the control site (43 ± 12%max) (all P ≤ 0.05). Sweat rate did not differ between sites throughout the protocol (all P > 0.05). We show that neither ET A nor ET B receptors modulate cutaneous vasodilation and sweating responses during and following moderate- and high-intensity exercise in the heat, with the exception that ET A receptors may partly contribute to the suppression of cutaneous vasodilation following high-intensity exercise. Copyright © 2016 the American Physiological Society.

Amphetamine modulation of long-term potentiation in the prefrontal cortex: dose dependency, monoaminergic contributions, and paradoxical rescue in hyperdopaminergic mutant.

PubMed

Xu, Tai-Xiang; Ma, Qi; Spealman, Roger D; Yao, Wei-Dong

2010-12-01

Amphetamine can improve cognition in healthy subjects and patients with schizophrenia, attention-deficit hyperactivity disorder, and other neuropsychiatric diseases; higher doses, however, can impair cognitive function, especially those mediated by the prefrontal cortex. We investigated how amphetamine affects prefrontal cortex long-term potentiation (LTP), a cellular correlate of learning and memory, in normal and hyperdopaminergic mice lacking the dopamine transporter. Acute amphetamine treatment in wild-type mice produced a biphasic dose-response modulation of LTP, with a low dose enhancing LTP and a high dose impairing it. Amphetamine-induced LTP enhancement was prevented by pharmacological blockade of D(1) - (but not D(2)-) class dopamine receptors, by blockade of β-adrenergic receptors, or by inhibition of cAMP-PKA signaling. In contrast, amphetamine-induced LTP impairment was prevented by inhibition of post-synaptic protein phosphatase-1, a downstream target of PKA signaling, or by blockade of either D(1) - or D(2)-class dopamine, but not noradrenergic, receptors. Thus, amphetamine biphasically modulates LTP via cAMP-PKA signaling orchestrated mainly through dopamine receptors. Unexpectedly, amphetamine restored the loss of LTP in dopamine transporter-knockout mice primarily by activation of the noradrenergic system. Our results mirror the biphasic effectiveness of amphetamine in humans and provide new mechanistic insights into its effects on cognition under normal and hyperdopaminergic conditions. © 2010 The Authors. Journal of Neurochemistry © 2010 International Society for Neurochemistry.

Blockade of GABA(A) receptors within the extended amygdala attenuates D(2) regulation of alcohol-motivated behaviors in the ventral tegmental area of alcohol-preferring (P) rats.

PubMed

Eiler, William J A; June, Harry L

2007-06-01

The dopamine (DA) mesolimbic pathway, which originates from DA cell bodies within the ventral tegmental area (VTA), has been shown by various studies to play a role in the mediation of various drugs of abuse including alcohol (EtOH). It has been suggested that the VTA's control of EtOH reward is mediated in part by the D2 receptors within the VTA. These receptors may be under the regulation of reciprocal GABAergic inputs from forebrain components of the mesolimbic path such as the nucleus accumbens (NAcc), a classic EtOH reward substrate, and the bed nucleus of the stria terminalis, a substrate recently implicated in EtOH reinforcement, forming a self-regulating feedback loop. To test this hypothesis, D2 regulation of EtOH self-administration (SA) was evaluated by the microinfusion of the D2 antagonist eticlopride into the VTA of P rats, which produced profound reductions in EtOH SA in the highest (20.0 and 40.0microg) doses tested in both BST/VTA and NAcc/VTA implanted P rats. To determine the role of GABA in the mediation of EtOH SA, a 32.0ng dose the non-selective GABA antagonist SR 95531 was microinfused into the BST producing no effect on responding for EtOH and into the NAcc which lead to a reduction in EtOH responding. Finally, the hypothesis that GABA innervation of the VTA from the mesolimbic forebrain may influence EtOH SA was examined by the simultaneous infusion of eticlopride (40.0microg) into the VTA and SR 95531 (32.0ng) into either the BST or NAcc. This combination infusion completely attenuated the reduction in EtOH SA observed with the 40.0microg dose of eticlopride alone in both groups of animals. These results suggest that while the D2 receptors within the VTA regulate EtOH-motivated behaviors, this is modulated by GABAergic input from the mesolimbic forebrain, specifically from the BST and NAcc.

GluN2B-containing NMDA receptors blockade rescues bidirectional synaptic plasticity in the bed nucleus of the stria terminalis of cocaine self-administering rats.

PubMed

deBacker, Julian; Hawken, Emily R; Normandeau, Catherine P; Jones, Andrea A; Di Prospero, Cynthia; Mechefske, Elysia; Gardner Gregory, James; Hayton, Scott J; Dumont, Éric C

2015-01-01

Drugs of abuse have detrimental effects on homeostatic synaptic plasticity in the motivational brain network. Bidirectional plasticity at excitatory synapses helps keep neural circuits within a functional range to allow for behavioral flexibility. Therefore, impaired bidirectional plasticity of excitatory synapses may contribute to the behavioral hallmarks of addiction, yet this relationship remains unclear. Here we tracked excitatory synaptic strength in the oval bed nucleus of the stria terminalis (ovBNST) using whole-cell voltage-clamp recordings in brain slices from rats self-administering sucrose or cocaine. In the cocaine group, we measured both a persistent increase in AMPA to NMDA ratio (A:N) and slow decay time of NMDA currents throughout the self-administration period and after withdrawal from cocaine. In contrast, the sucrose group exhibited an early increase in A:N ratios (acquisition) that returned toward baseline values with continued self-administration (maintenance) and after withdrawal. The sucrose rats also displayed a decrease in NMDA current decay time with continued self-administration (maintenance), which normalized after withdrawal. Cocaine self-administering rats exhibited impairment in NMDA-dependent long-term depression (LTD) that could be rescued by GluN2B-containing NMDA receptor blockade. Sucrose self-administering rats demonstrated no impairment in NMDA-dependent LTD. During the maintenance period of self-administration, in vivo (daily intraperitoneally for 5 days) pharmacologic blockade of GluN2B-containing NMDA receptors did not reduce lever pressing for cocaine. However, in vivo GluN2B blockade did normalize A:N ratios in cocaine self-administrating rats, and dissociated the magnitude of ovBNST A:N ratios from drug-seeking behavior after protracted withdrawal. Altogether, our data demonstrate when and how bidirectional plasticity at ovBNST excitatory synapses becomes dysfunctional with cocaine self-administration and that NMDA-mediated potentiation of AMPA receptors in this region may be part of the neural circuits of drug relapse.

Endothelin-1-induced contraction of pulmonary arteries from endotoxemic rats is attenuated by the endothelin-A receptor antagonist, BQ123.

PubMed

Curzen, N P; Mitchell, J A; Jourdan, K B; Griffiths, M J; Evans, T W

1996-12-01

Sepsis is characterized by systemic vasodilation and hyporesponsiveness to constrictor agents, at a time when the pulmonary circulation exhibits varying degrees of vasoconstriction. Plasma endothelin-1 concentrations are increased, but the role of this potent vasoconstrictor peptide in modulating the vascular response to sepsis is unknown. Therefore, we assessed the effect of endothelin-A receptor antagonism in the response of pulmonary arteries from rats treated with lipopolysaccharide to endothelin-1, and determined the vasomotor role of the endothelin-B receptors that are known to be located on rat pulmonary artery smooth muscle and endothelium. Prospective, controlled study. Animal research laboratory. Male Wistar rats (275 to 300 g). Animals were injected with either lipopolysaccharide (20 mg/kg i.p.) or saline (1 mL i.p.) 4 hrs before being killed. The main pulmonary arteries were cut into 2-mm rings, and suspended in an organ bath. In the first set of experiments, half of the rings underwent a procedure that removed the endothelium, and the contractile response to cumulative doses of endothelin-1 (10(-11) to 10(-6) M) was measured. Half of the rings were pretreated with the endothelin-A receptor antagonist, BQ123 (10(-5) M or 10(-6) M), and the other half of the rings were treated with vehicle. In a separate group of experiments, the contractile response to cumulative concentrations of the selective endothelin-B agonist, sarafotoxin S6c (10(-11) to 10(-6) M), was measured in rings at baseline tension. Second, the possible dilator effect of endothelin-B receptor activation was tested by the administration of sarafotoxin S6c (10(-7) to 10(-6) M) to rings preconstricted by 10(-6) M of U46619, a thromboxane receptor agonist, either in the presence or absence of the nitric oxide synthase inhibitor, N omega-nitro-L-arginine-methylester (10(-4) M). Acetylcholine-induced (10(-4) M), endothelium-dependent vasodilation was also measured. BQ123 (10(-5) or 10(-6) M) caused consecutive rightward shifts in the endothelin-1 concentration-contraction curves for all ring types, including the intact rings from endotoxemic animals. Sarafotoxin S6c failed to induce any direct constriction in rings from sham-treated or lipopolysaccharide-treated rats. However, sarafotoxin S6c induced transient vasodilation at the initial dose in rings from sham-treated rats but not lipopolysaccharide-treated rats-an effect that was attenuated by N omega-nitro-L-arginine-methylester. Acetylcholine induced an N omega-nitro-L-arginine-methylester-sensitive vasodilation that was reduced in rings from endotoxin-treated rats. Endothelin-A receptor blockade is an effective means of attenuating endothelin-1-induced contraction of isolated pulmonary artery rings, even from rats rendered endotoxemic. Endothelin-B receptors on the pulmonary artery cause vasodilation via the release of nitric oxide, and have no constrictor component. The functional effects of endothelin-B receptors on tone are lost after lipopolysaccharide treatment. The endothelium is involved in both the constrictor and dilator effects of endothelin in rat pulmonary artery, confirming a pivotal role for endothelial cells in the vascular response to sepsis.

MEK blockade converts AML differentiating response to retinoids into extensive apoptosis.

PubMed

Milella, Michele; Konopleva, Marina; Precupanu, Cristina M; Tabe, Yoko; Ricciardi, Maria Rosaria; Gregorj, Chiara; Collins, Steven J; Carter, Bing Z; D'Angelo, Carmen; Petrucci, Maria Teresa; Foà, Robin; Cognetti, Francesco; Tafuri, Agostino; Andreeff, Michael

2007-03-01

The aberrant function of transcription factors and/or kinase-based signaling pathways that regulate the ability of hematopoietic cells to proliferate, differentiate, and escape apoptosis accounts for the leukemic transformation of myeloid progenitors. Here, we demonstrate that simultaneous retinoid receptor ligation and blockade of the MEK/ERK signaling module, using the small-molecule inhibitor CI-1040, result in a strikingly synergistic induction of apoptosis in both acute myeloid leukemia (AML) and acute promyelocytic leukemia (APL) cells with constitutive ERK activation. This proapoptotic synergism requires functional RAR and RXR retinoid receptors, as demonstrated using RAR- and RXR-selective ligands and RAR-defective cells. In the presence of MEK inhibitors, however, retinoid-induced chromatin remodeling, target-gene transcription, and granulocytic differentiation are strikingly inhibited and apoptosis induction becomes independent of death-inducing ligand/receptor pairs; this suggests that apoptosis induction by combined retinoids and MEK inhibitors is entirely distinct from the classical "postmaturation" apoptosis induced by retinoids alone. Finally, we identify disruption of Bcl-2-dependent mitochondrial homeostasis as a possible point of convergence for the proapoptotic synergism observed with retinoids and MEK inhibitors. Taken together, these results indicate that combined retinoid treatment and MEK blockade exert powerful antileukemic effects and could be developed into a novel therapeutic strategy for both AML and APL.

Notch2 blockade enhances hematopoietic stem cell mobilization and homing.

PubMed

Wang, Weihuan; Yu, Shuiliang; Myers, Jay; Wang, Yiwei; Xin, William W; Albakri, Marwah; Xin, Alison W; Li, Ming; Huang, Alex Y; Xin, Wei; Siebel, Christian W; Lazarus, Hillard M; Zhou, Lan

2017-10-01

Despite use of newer approaches, some patients being considered for autologous hematopoietic cell transplantation (HCT) may only mobilize limited numbers of hematopoietic progenitor cells (HPCs) into blood, precluding use of the procedure, or being placed at increased risk of complications due to slow hematopoietic reconstitution. Developing more efficacious HPC mobilization regimens and strategies may enhance the mobilization process and improve patient outcome. Although Notch signaling is not essential for homeostasis of adult hematopoietic stem cells (HSCs), Notch-ligand adhesive interaction maintains HSC quiescence and niche retention. Using Notch receptor blocking antibodies, we report that Notch2 blockade, but not Notch1 blockade, sensitizes hematopoietic stem cells and progenitors (HSPCs) to mobilization stimuli and leads to enhanced egress from marrow to the periphery. Notch2 blockade leads to transient myeloid progenitor expansion without affecting HSC homeostasis and self-renewal. We show that transient Notch2 blockade or Notch2-loss in mice lacking Notch2 receptor lead to decreased CXCR4 expression by HSC but increased cell cycling with CXCR4 transcription being directly regulated by the Notch transcriptional protein RBPJ. In addition, we found that Notch2-blocked or Notch2-deficient marrow HSPCs show an increased homing to the marrow, while mobilized Notch2-blocked, but not Notch2-deficient stem cells and progenitors, displayed a competitive repopulating advantage and enhanced hematopoietic reconstitution. These findings suggest that blocking Notch2 combined with the current clinical regimen may further enhance HPC mobilization and improve engraftment during HCT. Copyright© 2017 Ferrata Storti Foundation.

Human CAR T cells with cell-intrinsic PD-1 checkpoint blockade resist tumor-mediated inhibition

PubMed Central

Cherkassky, Leonid; Morello, Aurore; Villena-Vargas, Jonathan; Feng, Yang; Dimitrov, Dimiter S.; Jones, David R.; Sadelain, Michel; Adusumilli, Prasad S.

2016-01-01

Following immune attack, solid tumors upregulate coinhibitory ligands that bind to inhibitory receptors on T cells. This adaptive resistance compromises the efficacy of chimeric antigen receptor (CAR) T cell therapies, which redirect T cells to solid tumors. Here, we investigated whether programmed death-1–mediated (PD-1–mediated) T cell exhaustion affects mesothelin-targeted CAR T cells and explored cell-intrinsic strategies to overcome inhibition of CAR T cells. Using an orthotopic mouse model of pleural mesothelioma, we determined that relatively high doses of both CD28- and 4-1BB–based second-generation CAR T cells achieved tumor eradication. CAR-mediated CD28 and 4-1BB costimulation resulted in similar levels of T cell persistence in animals treated with low T cell doses; however, PD-1 upregulation within the tumor microenvironment inhibited T cell function. At lower doses, 4-1BB CAR T cells retained their cytotoxic and cytokine secretion functions longer than CD28 CAR T cells. The prolonged function of 4-1BB CAR T cells correlated with improved survival. PD-1/PD-1 ligand [PD-L1] pathway interference, through PD-1 antibody checkpoint blockade, cell-intrinsic PD-1 shRNA blockade, or a PD-1 dominant negative receptor, restored the effector function of CD28 CAR T cells. These findings provide mechanistic insights into human CAR T cell exhaustion in solid tumors and suggest that PD-1/PD-L1 blockade may be an effective strategy for improving the potency of CAR T cell therapies. PMID:27454297

Direct stimulation of angiotensin II type 2 receptor initiated after stroke ameliorates ischemic brain damage.

PubMed

Min, Li-Juan; Mogi, Masaki; Tsukuda, Kana; Jing, Fei; Ohshima, Kousei; Nakaoka, Hirotomo; Kan-No, Harumi; Wang, Xiao-Li; Chisaka, Toshiyuki; Bai, Hui-Yu; Iwanami, Jun; Horiuchi, Masatsugu

2014-08-01

Stroke is a leading cause of death and disability; however, meta-analysis of randomized controlled trials of blood pressure-lowering drugs in acute stroke has shown no definite evidence of a beneficial effect on functional outcome. Accumulating evidence suggests that angiotensin II type 1 receptor blockade with angiotensin II type 2 (AT2) receptor stimulation could contribute to protection against ischemic brain damage. We examined the possibility that direct AT2 receptor stimulation by compound 21 (C21) initiated even after stroke can prevent ischemic brain damage. Stroke was induced by middle cerebral artery (MCA) occlusion, and the area of cerebral infarction was measured by magnetic resonant imaging. C21 (10 µg/kg/day) treatment was initiated immediately after MCA occlusion by intraperitoneal injection followed by treatment with C21 once daily. We observed that ischemic area was enlarged in a time dependent fashion and decreased on day 5 after MCA occlusion. Treatment with C21 initiated after MCA occlusion significantly reduced the ischemic area, with improvement of neurological deficit in a time-dependent manner without affecting blood pressure. The decrease of cerebral blood flow after MCA occlusion was also ameliorated by C21 treatment. Moreover, treatment with C21 significantly attenuated superoxide anion production and expression of proinflammatory cytokines, monocyte chemoattractant protein 1, and tumor necrosis factor α. Interestingly, C21 administration significantly decreased blood-brain barrier permeability and cerebral edema on the ischemic side. These results provide new evidence that direct AT2 receptor stimulation with C21 is a novel therapeutic approach to prevent ischemic brain damage after acute stroke. © American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Bradykinin activates a cross-signaling pathway between sensory and adrenergic nerve endings in the heart: a novel mechanism of ischemic norepinephrine release?

PubMed

Seyedi, N; Maruyama, R; Levi, R

1999-08-01

We had shown that bradykinin (BK) generated by cardiac sympathetic nerve endings (i.e., synaptosomes) promotes exocytotic norepinephrine (NE) release in an autocrine mode. Because the synaptosomal preparation may include sensory C-fiber endings, which BK is known to stimulate, sensory nerves could contribute to the proadrenergic effects of BK in the heart. We report that BK is a potent releaser of NE from guinea pig heart synaptosomes (EC(50) approximately 20 nM), an effect mediated by B(2) receptors, and almost completely abolished by prior C-fiber destruction or blockade of calcitonin gene-related peptide and neurokinin-1 receptors. C-fiber destruction also greatly decreased BK-induced NE release from the intact heart, whereas tyramine-induced NE release was unaffected. Furthermore, C-fiber stimulation with capsaicin and activation of calcitonin gene-related peptide and neurokinin-1 receptors initiated NE release from cardiac synaptosomes, indicating that stimulation of sensory neurons in turn activates sympathetic nerve terminals. Thus, BK is likely to release NE in the heart in part by first liberating calcitonin gene-related peptide and Substance P from sensory nerve endings; these neuropeptides then stimulate specific receptors on sympathetic terminals. This action of BK is positively modulated by cyclooxygenase products, attenuated by activation of histamine H(3) receptors, and potentiated at a lower pH. The NE-releasing action of BK is likely to be enhanced in myocardial ischemia, when protons accumulate, C fibers become activated, and the production of prostaglandins and BK increases. Because NE is a major arrhythmogenic agent, the activation of this interneuronal signaling system between sensory and adrenergic neurons may contribute to ischemic dysrhythmias and sudden cardiac death.

Biflorin Ameliorates Memory Impairments Induced by Cholinergic Blockade in Mice

PubMed Central

Jeon, Se Jin; Kim, Boseong; Ryu, Byeol; Kim, Eunji; Lee, Sunhee; Jang, Dae Sik; Ryu, Jong Hoon

2017-01-01

To examine the effect of biflorin, a component of Syzygium aromaticum, on memory deficit, we introduced a scopolamine-induced cognitive deficit mouse model. A single administration of biflorin increased latency time in the passive avoidance task, ameliorated alternation behavior in the Y-maze, and increased exploration time in the Morris water maze task, indicating the improvement of cognitive behaviors against cholinergic dysfunction. The biflorin-induced reverse of latency in the scopolamine-treated group was attenuated by MK-801, an NMDA receptor antagonist. Biflorin also enhanced cognitive function in a naïve mouse model. To understand the mechanism of biflorin for memory amelioration, we performed Western blot. Biflorin increased the activation of protein kinase C-ζ and its downstream signaling molecules in the hippocampus. These results suggest that biflorin ameliorates drug-induced memory impairment by modulation of protein kinase C-ζ signaling in mice, implying that biflorin could function as a possible therapeutic agent for the treatment of cognitive problems. PMID:27829270

The Role of Endorphins in the Pathophysiology of Hemorrhagic and Endotoxic Shock in the Subhuman Primate.

DTIC Science & Technology

1985-03-15

by either a- or e-adrenergic blockade (phenoxybenzamine or metoprolol , respectively) and potentiated by cholinergic receptor *blockade with...which was blocked by e-adrenergic blockade with metoprolol . Naloxone had no effect on plasma catecholamine levels (Table V). The sustained cardiovascular...58±8 213±134 57:5C Shock Saline 19.3:3.7 8.6±2.8 1.4:0.2 Metoprolol 21.1±7.0 5.2t1.3 1.0:0.2 Phenox y- benzamine 9.4:1.5 4.2±0.5 1.0:0.2 Both 14.1±3.5

Pharmacological blockade of either cannabinoid CB1 or CB2 receptors prevents both cocaine-induced conditioned locomotion and cocaine-induced reduction of cell proliferation in the hippocampus of adult male rat

PubMed Central

Blanco-Calvo, Eduardo; Rivera, Patricia; Arrabal, Sergio; Vargas, Antonio; Pavón, Francisco Javier; Serrano, Antonia; Castilla-Ortega, Estela; Galeano, Pablo; Rubio, Leticia; Suárez, Juan; Rodriguez de Fonseca, Fernando

2014-01-01

Addiction to major drugs of abuse, such as cocaine, has recently been linked to alterations in adult neurogenesis in the hippocampus. The endogenous cannabinoid system modulates this proliferative response as demonstrated by the finding that pharmacological activation/blockade of cannabinoid CB1 and CB2 receptors not only modulates neurogenesis but also modulates cell death in the brain. In the present study, we evaluated whether the endogenous cannabinoid system affects cocaine-induced alterations in cell proliferation. To this end, we examined whether pharmacological blockade of either CB1 (Rimonabant, 3 mg/kg) or CB2 receptors (AM630, 3 mg/kg) would affect cell proliferation [the cells were labeled with 5-bromo-2′-deoxyuridine (BrdU)] in the subventricular zone (SVZ) of the lateral ventricle and the dentate subgranular zone (SGZ). Additionally, we measured cell apoptosis (as monitored by the expression of cleaved caspase-3) and glial activation [by analyzing the expression of glial fibrillary acidic protein (GFAP) and Iba-1] in the striatum and hippocampus during acute and repeated (4 days) cocaine administration (20 mg/kg). The results showed that acute cocaine exposure decreased the number of BrdU-immunoreactive (ir) cells in the SVZ and SGZ. In contrast, repeated cocaine exposure reduced the number of BrdU-ir cells only in the SVZ. Both acute and repeated cocaine exposure increased the number of cleaved caspase-3-, GFAP- and Iba1-ir cells in the hippocampus, and this effect was counteracted by AM630 or Rimonabant, which increased the number of BrdU-, GFAP-, and Iba1-ir cells in the hippocampus. These results indicate that the changes in neurogenic, apoptotic and gliotic processes that were produced by repeated cocaine administration were normalized by pharmacological blockade of CB1 and CB2. The restorative effects of cannabinoid receptor blockade on hippocampal cell proliferation were associated with the prevention of the induction of conditioned locomotion but not with the prevention of cocaine-induced sensitization. PMID:24409127

Systemic and regional flow distribution in normotensive and spontaneously hypertensive young rats subjected to lifetime beta-adrenergic receptor blockade.

PubMed

Nishiyama, K; Nishiyama, A; Pfeffer, M A; Frohlich, E D

1978-01-01

To determine quantitatively organ blood flow distribution as the result of lifelong beta-adrenergic receptor blockade, 23 and 24 normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats, respectively, were treated from conception with tap water (control; 10 WKY and 8 SHR), propranolol (0.5 mg/ml drinking water; 6 WKY and 8 SHR), or timolol (0.5 mg/ml drinking water; 7 WKY and 8 SHR) via placental circulation, mothers' milk, and drinking water. At 12 weeks of age all six groups were studied hemodynamically under ether anesthesia using an electromagnetic flowmeter and radioactive carbonized (15 micrometer) microspheres. Untreated SHR demonstrated normal cardiac output (CO) and CO distribution to all organs except for myocardium and testes, thereby confirming our previous work. With either propranolol or timolol treatment the course of development and maintenance of arterial pressure was no different than the pure-tap-water-fed WKY and SHR despite an approximate 30% reduction in CO. Further, with both beta-receptor antagonists CO distribution was significantly reduced to skeletal muscle (p less than 0.001), unchanged to the heart, and increased (p less than 0.05) to the remaining organs (including kidneys and brain) in both groups. Thus, as a result of lifelong beta-adrenergic receptor blockade, CO was reduced; and this was associated with a redistribution of blood flow so that flow to the kidney, brain, and splanchnic organs could be maintained at the expense of skeletal muslce perfusion.

Pituitary adenylate cyclase 1 receptor internalization and endosomal signaling mediate the pituitary adenylate cyclase activating polypeptide-induced increase in guinea pig cardiac neuron excitability.

PubMed

Merriam, Laura A; Baran, Caitlin N; Girard, Beatrice M; Hardwick, Jean C; May, Victor; Parsons, Rodney L

2013-03-06

After G-protein-coupled receptor activation and signaling at the plasma membrane, the receptor complex is often rapidly internalized via endocytic vesicles for trafficking into various intracellular compartments and pathways. The formation of signaling endosomes is recognized as a mechanism that produces sustained intracellular signals that may be distinct from those generated at the cell surface for cellular responses including growth, differentiation, and survival. Pituitary adenylate cyclase activating polypeptide (PACAP; Adcyap1) is a potent neurotransmitter/neurotrophic peptide and mediates its diverse cellular functions in part through internalization of its cognate G-protein-coupled PAC1 receptor (PAC1R; Adcyap1r1). In the present study, we examined whether PAC1R endocytosis participates in the regulation of neuronal excitability. Although PACAP increased excitability in 90% of guinea pig cardiac neurons, pretreatment with Pitstop 2 or dynasore to inhibit clathrin and dynamin I/II, respectively, suppressed the PACAP effect. Subsequent addition of inhibitor after the PACAP-induced increase in excitability developed gradually attenuated excitability with no changes in action potential properties. Likewise, the PACAP-induced increase in excitability was markedly decreased at ambient temperature. Receptor trafficking studies with GFP-PAC1 cell lines demonstrated the efficacy of Pitstop 2, dynasore, and low temperatures at suppressing PAC1R endocytosis. In contrast, brefeldin A pretreatments to disrupt Golgi vesicle trafficking did not blunt the PACAP effect, and PACAP/PAC1R signaling still increased neuronal cAMP production even with endocytic blockade. Our results demonstrate that PACAP/PAC1R complex endocytosis is a key step for the PACAP modulation of cardiac neuron excitability.

Selective CD28 blockade attenuates CTLA-4–dependent CD8+ memory T cell effector function and prolongs graft survival

PubMed Central

Liu, Danya; Badell, I. Raul; Ford, Mandy L.

2018-01-01

Memory T cells pose a significant problem to successful therapeutic control of unwanted immune responses during autoimmunity and transplantation, as they are differentially controlled by cosignaling receptors such as CD28 and CTLA-4. Treatment with abatacept and belatacept impede CD28 signaling by binding to CD80 and CD86, but they also have the unintended consequence of blocking the ligands for CTLA-4, a process that may inadvertently boost effector responses. Here, we show that a potentially novel anti-CD28 domain antibody (dAb) that selectively blocks CD28 but preserves CTLA-4 coinhibition confers improved allograft survival in sensitized recipients as compared with CTLA-4 Ig. However, both CTLA-4 Ig and anti-CD28 dAb similarly and significantly reduced the accumulation of donor-reactive CD8+ memory T cells, demonstrating that regulation of the expansion of CD8+ memory T cell populations is controlled in part by CD28 signals and is not significantly impacted by CTLA-4. In contrast, selective CD28 blockade was superior to CTLA-4 Ig in inhibiting IFN-γ, TNF, and IL-2 production by CD8+ memory T cells, which in turn resulted in reduced recruitment of innate CD11b+ monocytes into allografts. Importantly, this superiority was CTLA-4 dependent, demonstrating that effector function of CD8+ memory T cells is regulated by the balance of CD28 and CTLA-4 signaling. PMID:29321374

Resistant Hypertension On Treatment (ResHypOT): sequential nephron blockade compared to dual blockade of the renin-angiotensin-aldosterone system plus bisoprolol in the treatment of resistant arterial hypertension - study protocol for a randomized controlled trial.

PubMed

Cestário, Elizabeth do Espirito Santo; Fernandes, Letícia Aparecida Barufi; Giollo-Júnior, Luiz Tadeu; Uyemura, Jéssica Rodrigues Roma; Matarucco, Camila Suemi Sato; Landim, Manoel Idelfonso Paz; Cosenso-Martin, Luciana Neves; Tácito, Lúcia Helena Bonalume; Moreno, Heitor; Vilela-Martin, José Fernando; Yugar-Toledo, Juan Carlos

2018-02-12

Resistant hypertension is characterized when the blood pressure (BP) remains above the recommended goal after taking three antihypertensive drugs with synergistic actions at their maximum recommended tolerated doses, preferably including a diuretic. Identifying the contribution of intravascular volume and serum renin in maintaining BP levels could help tailor more effective hypertension treatment, whether acting on the control of intravascular volume or sodium balance, or acting on the effects of the renin-angiotensin-aldosterone system (RAAS) on the kidney. This is a randomized, open-label, clinical trial is designed to compare sequential nephron blockade and its contribution to the intravascular volume component with dual blockade of the RAAS plus bisoprolol and the importance of serum renin in maintaining BP levels. The trial has two arms: sequential nephron blockade versus dual blockade of the RAAS (with an angiotensin converting enzyme (ACE) inhibitor plus a beta-blocker) both added-on to a thiazide diuretic, a calcium-channel blocker and an angiotensin receptor-1 blocker (ARB). Sequential nephron blockade consists in a progressive increase in sodium depletion using a thiazide diuretic, an aldosterone-receptor blocker, furosemide and, finally, amiloride. On the other hand, the dual blockade of the RAAS consists of the progressive addition of an ACE inhibitor until the maximum dose and then the administration of a beta-blocker until the maximum dose. The primary outcomes will be reductions in the systolic BP, diastolic BP, mean BP and pulse pressure (PP) after 20 weeks of treatment. The secondary outcomes will evaluate treatment safety and tolerability, biochemical changes, evaluation of renal function and recognition of hypotension (ambulatory BP monitoring (ABPM)). The sample size was calculated assuming an alpha error of 5% to reject the null hypothesis with a statistical power of 80% giving a total of 40 individuals per group. In recent years, the cost of resistant hypertension (RH) treatment has increased. Thus, identifying the contribution of intravascular volume and serum renin in maintaining BP levels could help tailor more effective hypertension treatment, whether by acting on the control of intravascular volume or sodium balance, or by acting on the effects of the RAAS on the kidney. Sequential Nephron Blockade vs. Dual Blockade Renin-angiotensin System + Bisoprolol in Resistant Arterial Hypertension (ResHypOT). ClinicalTrials.gov, ID: NCT02832973 . Registered on 14 July 2016. First received: 12 June 2016. Last updated: 18 July 2016.

The potential role of dopamine D3 receptor neurotransmission in cognition

PubMed Central

Nakajima, Shinichiro; Gerretsen, Philip; Takeuchi, Hiroyoshi; Caravaggio, Fernando; Chow, Tiffany; Le Foll, Bernard; Mulsant, Benoit; Pollock, Bruce; Graff-Guerrero, Ariel

2013-01-01

Currently available treatments have limited pro-cognitive effects for neuropsychiatric disorders, such as schizophrenia, Parkinson’s disease and Alzheimer’s disease. The primary objective of this work is to review the literature on the role of dopamine D3 receptors in cognition, and propose dopamine D3 receptor antagonists as possible cognitive enhancers for neuropsychiatric disorders. A literature search was performed to identify animal and human studies on D3 receptors and cognition using PubMed, MEDLINE and EMBASE. The search terms included “dopamine D3 receptor” and “cognition”. The literature search identified 164 articles. The results revealed: (1) D3 receptors are associated with cognitive functioning in both healthy individuals and those with neuropsychiatric disorders; (2) D3 receptor blockade appears to enhance while D3 receptor agonism seems to impair cognitive function, including memory, attention, learning, processing speed, social recognition and executive function independent of age; and (3) D3 receptor antagonists may exert their pro-cognitive effect by enhancing the release of acetylcholine in the prefrontal cortex, disinhibiting the activity of dopamine neurons projecting to the nucleus accumbens or prefrontal cortex, or activating CREB signaling in the hippocampus. These findings suggest that D3 receptor blockade may enhance cognitive performance in healthy individuals and treat cognitive dysfunction in individuals with a neuropsychiatric disorder. Clinical trials are needed to confirm these effects. PMID:23791072

Evidence that opioids may have toll-like receptor 4 and MD-2 effects.

PubMed

Hutchinson, Mark R; Zhang, Yingning; Shridhar, Mitesh; Evans, John H; Buchanan, Madison M; Zhao, Tina X; Slivka, Peter F; Coats, Benjamen D; Rezvani, Niloofar; Wieseler, Julie; Hughes, Travis S; Landgraf, Kyle E; Chan, Stefanie; Fong, Stephanie; Phipps, Simon; Falke, Joseph J; Leinwand, Leslie A; Maier, Steven F; Yin, Hang; Rice, Kenner C; Watkins, Linda R

2010-01-01

Opioid-induced proinflammatory glial activation modulates wide-ranging aspects of opioid pharmacology including: opposition of acute and chronic opioid analgesia, opioid analgesic tolerance, opioid-induced hyperalgesia, development of opioid dependence, opioid reward, and opioid respiratory depression. However, the mechanism(s) contributing to opioid-induced proinflammatory actions remains unresolved. The potential involvement of toll-like receptor 4 (TLR4) was examined using in vitro, in vivo, and in silico techniques. Morphine non-stereoselectively induced TLR4 signaling in vitro, blocked by a classical TLR4 antagonist and non-stereoselectively by naloxone. Pharmacological blockade of TLR4 signaling in vivo potentiated acute intrathecal morphine analgesia, attenuated development of analgesic tolerance, hyperalgesia, and opioid withdrawal behaviors. TLR4 opposition to opioid actions was supported by morphine treatment of TLR4 knockout mice, which revealed a significant threefold leftward shift in the analgesia dose response function, versus wildtype mice. A range of structurally diverse clinically-employed opioid analgesics was found to be capable of activating TLR4 signaling in vitro. Selectivity in the response was identified since morphine-3-glucuronide, a morphine metabolite with no opioid receptor activity, displayed significant TLR4 activity, whilst the opioid receptor active metabolite, morphine-6-glucuronide, was devoid of such properties. In silico docking simulations revealed ligands bound preferentially to the LPS binding pocket of MD-2 rather than TLR4. An in silico to in vitro prediction model was built and tested with substantial accuracy. These data provide evidence that select opioids may non-stereoselectively influence TLR4 signaling and have behavioral consequences resulting, in part, via TLR4 signaling.

Evidence that opioids may have toll like receptor 4 and MD-2 effects

PubMed Central

Hutchinson, Mark R.; Zhang, Yingning; Shridhar, Mitesh; Evans, John H.; Buchanan, Madison M.; Zhao, Tina X.; Slivka, Peter F.; Coats, Benjamen D.; Rezvani, Niloofar; Wieseler, Julie; Hughes, Travis S.; Landgraf, Kyle E.; Chan, Stefanie; Fong, Stephanie; Phipps, Simon; Falke, Joseph J.; Leinwand, Leslie A.; Maier, Steven F.; Yin, Hang; Rice, Kenner C.; Watkins, Linda R.

2009-01-01

Opioid-induced proinflammatory glial activation modulates wide-ranging aspects of opioid pharmacology including: opposition of acute and chronic opioid analgesia, opioid analgesic tolerance, opioid-induced hyperalgesia, development of opioid dependence, opioid reward, and opioid respiratory depression. However, the mechanism(s) contributing to opioid-induced proinflammatory actions remains unresolved. The potential involvement of toll like receptor 4 (TLR4) was examined using in vitro, in vivo, and in silico techniques. Morphine non-stereoselectively induced TLR4 signaling in vitro, blocked by a classical TLR4 antagonist and non-stereoselectively by naloxone. Pharmacological blockade of TLR4 signaling in vivo potentiated acute intrathecal morphine analgesia, attenuated development of analgesic tolerance, hyperalgesia, and opioid withdrawal behaviors. TLR4 opposition to opioid actions was supported by morphine treatment of TLR4 knockout mice, which revealed a significant threefold leftward shift in the analgesia dose response function, versus wildtype mice. A range of structurally diverse clinically employed opioid analgesics was found to be capable of activating TLR4 signaling in vitro. Selectivity in the response was identified since morphine-3-glucuronide, a morphine metabolite with no opioid receptor activity, displayed significant TLR4 activity, whilst the opioid receptor active metabolite, morphine-6-glucuronide, was devoid of such properties. In silico docking simulations revealed ligands bound preferentially to the LPS binding pocket of MD-2 rather than TLR4. An in silico to in vitro prediction model was built and tested with substantial accuracy. These data provide evidence that select opioids may non-stereoselectively influence TLR4 signaling and have behavioral consequences resulting, in part, via TLR4 signaling. PMID:19679181

Selective activation of estrogen receptors, ERα and GPER-1, rapidly decreases food intake in female rats.

PubMed

Butler, Michael J; Hildebrandt, Ryan P; Eckel, Lisa A

2018-05-25

Many of estradiol's behavioral effects are mediated, at least partially, via extra-nuclear estradiol signaling. Here, we investigated whether two estrogen receptor (ER) agonists, targeting ERα and G protein-coupled ER-1 (GPER-1), can promote rapid anorexigenic effects. Food intake was measured in ovariectomized (OVX) rats at 1, 2, 4, and 22 h following subcutaneous (s.c.) injection of an ERα agonist (PPT; 0-200 μg/kg), a GPER-1 agonist (G-1; 0-1600 μg/kg), and a GPER-1 antagonist (G-36; 0-80 μg/kg). To investigate possible cross-talk between ERα and GPER-1, we examined whether GPER-1 blockade affects the anorexigenic effect of PPT. Feeding was monitored in OVX rats that received s.c. injections of vehicle or 40 μg/kg G-36 followed 30 min later by s.c. injections of vehicle or 200 μg/kg PPT. Selective activation of ERα and GPER-1 alone decreased food intake within 1 h of drug treatment, and feeding remained suppressed for 22 h following PPT treatment and 4 h following G-1 treatment. Acute administration of G-36 alone did not suppress feeding at any time point. Blockade of GPER-1 attenuated PPT's rapid (within 1 h) anorexigenic effect, but did not modulate PPT's ability to suppress food intake at 2, 4 and 22 h. These findings demonstrate that selective activation of ERα produces a rapid (within 1 h) decrease in food intake that is best explained by a non-genomic signaling pathway and thus implicates the involvement of extra-nuclear ERα. Our findings also provide evidence that activation of GPER-1 is both sufficient to suppress feeding and necessary for PPT's rapid anorexigenic effect. Copyright © 2017. Published by Elsevier Inc.

Effects of Kefir on the Cardiac Autonomic Tones and Baroreflex Sensitivity in Spontaneously Hypertensive Rats

PubMed Central

Klippel, Brunella F.; Duemke, Licia B.; Leal, Marcos A.; Friques, Andreia G. F.; Dantas, Eduardo M.; Dalvi, Rodolfo F.; Gava, Agata L.; Pereira, Thiago M. C.; Andrade, Tadeu U.; Meyrelles, Silvana S.; Campagnaro, Bianca P.; Vasquez, Elisardo C.

2016-01-01

Aims: It has been previously shown that the probiotic kefir (a symbiotic matrix containing acid bacteria and yeasts) attenuated the hypertension and the endothelial dysfunction in spontaneously hypertensive rats (SHR). In the present study, the effect of chronic administration of kefir on the cardiac autonomic control of heart rate (HR) and baroreflex sensitivity (BRS) in SHR was evaluated. Methods: SHR were treated with kefir (0.3 mL/100 g body weight) for 60 days and compared with non-treated SHR and with normotensive Wistar-Kyoto rats. Cardiac autonomic vagal (VT) and sympathetic (ST) tones were estimated through the blockade of the cardiac muscarinic receptors (methylatropine) and the blockade of β1−adrenoceptor (atenolol). The BRS was evaluated by the tachycardia and bradycardia responses to vasoactive drug-induced decreases and increases in arterial blood pressure (BP), respectively. Additionally, spontaneous BRS was estimated by autoregressive spectral analysis. Results: Kefir-treated SHR exhibited significant attenuation of basal BP, HR, and cardiac hypertrophy compared to non-treated SHR (12, 13, and 21%, respectively). Cardiac VT and ST were significantly altered in the SHR (~40 and ~90 bpm) compared with Wistar rats (~120 and ~30 bpm) and were partially recovered in SHR-kefir (~90 and ~25 bpm). SHR exhibited an impaired bradycardic BRS (~50%) compared with Wistar rats, which was reduced to ~40% in the kefir-treated SHR and abolished by methylatropine in all groups. SHR also exhibited a significant impairment of the tachycardic BRS (~23%) compared with Wistar rats and this difference was reduced to 8% in the SHR-kefir. Under the action of atenolol the residual reflex tachycardia was smaller in SHR than in Wistar rats and kefir attenuated this abnormality. Spectral analysis revealed increased low frequency components of BP (~3.5-fold) and pulse interval (~2-fold) compared with Wistar rats and these differences were reduced by kefir-treatment to ~1.6- and ~1.5-fold, respectively. Spectral analysis also showed an impairment of spontaneous BRS in SHR, but kefir-treatment caused only a tendency to reverse this result. Conclusions: The novelty of this study is that daily chronic consumption of a low dose of kefir reduced the impairment of the cardiac autonomic control of HR and of the impaired BRS in SHR. PMID:27375490

Effects of Kefir on the Cardiac Autonomic Tones and Baroreflex Sensitivity in Spontaneously Hypertensive Rats.

PubMed

Klippel, Brunella F; Duemke, Licia B; Leal, Marcos A; Friques, Andreia G F; Dantas, Eduardo M; Dalvi, Rodolfo F; Gava, Agata L; Pereira, Thiago M C; Andrade, Tadeu U; Meyrelles, Silvana S; Campagnaro, Bianca P; Vasquez, Elisardo C

2016-01-01

It has been previously shown that the probiotic kefir (a symbiotic matrix containing acid bacteria and yeasts) attenuated the hypertension and the endothelial dysfunction in spontaneously hypertensive rats (SHR). In the present study, the effect of chronic administration of kefir on the cardiac autonomic control of heart rate (HR) and baroreflex sensitivity (BRS) in SHR was evaluated. SHR were treated with kefir (0.3 mL/100 g body weight) for 60 days and compared with non-treated SHR and with normotensive Wistar-Kyoto rats. Cardiac autonomic vagal (VT) and sympathetic (ST) tones were estimated through the blockade of the cardiac muscarinic receptors (methylatropine) and the blockade of β1-adrenoceptor (atenolol). The BRS was evaluated by the tachycardia and bradycardia responses to vasoactive drug-induced decreases and increases in arterial blood pressure (BP), respectively. Additionally, spontaneous BRS was estimated by autoregressive spectral analysis. Kefir-treated SHR exhibited significant attenuation of basal BP, HR, and cardiac hypertrophy compared to non-treated SHR (12, 13, and 21%, respectively). Cardiac VT and ST were significantly altered in the SHR (~40 and ~90 bpm) compared with Wistar rats (~120 and ~30 bpm) and were partially recovered in SHR-kefir (~90 and ~25 bpm). SHR exhibited an impaired bradycardic BRS (~50%) compared with Wistar rats, which was reduced to ~40% in the kefir-treated SHR and abolished by methylatropine in all groups. SHR also exhibited a significant impairment of the tachycardic BRS (~23%) compared with Wistar rats and this difference was reduced to 8% in the SHR-kefir. Under the action of atenolol the residual reflex tachycardia was smaller in SHR than in Wistar rats and kefir attenuated this abnormality. Spectral analysis revealed increased low frequency components of BP (~3.5-fold) and pulse interval (~2-fold) compared with Wistar rats and these differences were reduced by kefir-treatment to ~1.6- and ~1.5-fold, respectively. Spectral analysis also showed an impairment of spontaneous BRS in SHR, but kefir-treatment caused only a tendency to reverse this result. The novelty of this study is that daily chronic consumption of a low dose of kefir reduced the impairment of the cardiac autonomic control of HR and of the impaired BRS in SHR.

Different MK-801 administration schedules induce mild to severe learning impairments in an operant conditioning task: role of buspirone and risperidone in ameliorating these cognitive deficits.

PubMed

Rapanelli, Maximiliano; Frick, Luciana Romina; Bernardez-Vidal, Micaela; Zanutto, Bonifacio Silvano

2013-11-15

Blockade of N-methyl-d-aspartate receptor (NMDA) by the noncompetitive NMDA receptor (NMDAR) antagonist MK-801 produces behavioral abnormalities and alterations in prefrontal cortex (PFC) functioning. Due to the critical role of the PFC in operant conditioning task learning, we evaluated the effects of acute, repeated postnatal injections of MK-801 (0.1mg/kg) on learning performance. We injected Long-Evans rats i.p. with MK-801 (0.1mg/kg) using three different administration schedules: injection 40 min before beginning the task (during) (n=12); injection twice daily for six consecutive days prior to beginning the experimental procedures (prior) (n=12); or twice daily subcutaneous injections from postnatal day 7 to 11 (postnatal) (n=12). Next, we orally administered risperidone (serotonin receptor 2A and dopamine receptor 2 antagonist, 1mg/kg) or buspirone (serotonin receptor 1A partial agonist, 10mg/kg) to animals treated with the MK-801 schedule described above. The postnatal and prior administration schedules produced severe learning deficits, whereas injection of MK-801 just before training sessions had only mild effects on acquisition of an operant conditioning. Risperidone was able to reverse the detrimental effect of MK-801 in the animals that were treated with MK-801 during and prior training sessions. In contrast, buspirone was only effective at mitigating the cognitive deficits induced by MK-801 when administered during the training procedures. The data demonstrates that NMDA antagonism disrupts basic mechanisms of learning in a simple PFC-mediated operant conditioning task, and that buspirone and risperidone failed to attenuate the learning deficits when NMDA neurotransmission was blocked in the early stages of the postnatal period. Copyright © 2013 Elsevier B.V. All rights reserved.

CD39 improves survival in microbial sepsis by attenuating systemic inflammation

PubMed Central

Csóka, Balázs; Németh, Zoltán H.; Törő, Gábor; Koscsó, Balázs; Kókai, Endre; Robson, Simon C.; Enjyoji, Keiichi; Rolandelli, Rolando H.; Erdélyi, Katalin; Pacher, Pál; Haskó, György

2015-01-01

Sepsis remains the leading cause of morbidity and mortality in critically ill patients. Excessive inflammation is a major cause of organ failure and mortality in sepsis. Ectonucleoside triphosphate diphosphohydrolase 1, ENTPDase1 (CD39) is a cell surface nucleotide-metabolizing enzyme, which degrades the extracellular purines ATP and ADP, thereby regulating purinergic receptor signaling. Although the role of purinergic receptor signaling in regulating inflammation and sepsis has been addressed previously, the role of CD39 in regulating the host’s response to sepsis is unknown. We found that the CD39 mimic apyrase (250 U/kg) decreased and knockout or pharmacologic blockade with sodium polyoxotungstate (5 mg/kg; IC50 ≈ 10 μM) of CD39 increased mortality of mice with polymicrobial sepsis induced by cecal ligation and puncture. CD39 decreased inflammation, organ damage, immune cell apoptosis, and bacterial load. Use of bone marrow chimeric mice revealed that CD39 expression on myeloid cells decreases inflammation in septic mice. CD39 expression is upregulated during sepsis in mice, as well as in both murine and human macrophages stimulated with Escherichia coli. Moreover, E. coli increases CD39 promoter activity in macrophages. Altogether, these data indicate CD39 as an evolutionarily conserved inducible protective pathway during sepsis. We propose CD39 as a novel therapeutic target in the management of sepsis.—Csóka, B., Németh, Z. H., Törő, G., Koscsó, B., Kókai, E., Robson, S. C., Enjyoji, K., Rolandelli, R. H., Erdélyi, K., Pacher, P., Haskó, G. CD39 improves survival in microbial sepsis by attenuating systemic inflammation. PMID:25318479

Horizon 2020 in Diabetic Kidney Disease: The Clinical Trial Pipeline for Add-On Therapies on Top of Renin Angiotensin System Blockade

PubMed Central

Perez-Gomez, Maria Vanessa; Sanchez-Niño, Maria Dolores; Sanz, Ana Belen; Martín-Cleary, Catalina; Ruiz-Ortega, Marta; Egido, Jesus; Navarro-González, Juan F.; Ortiz, Alberto; Fernandez-Fernandez, Beatriz

2015-01-01

Diabetic kidney disease is the most frequent cause of end-stage renal disease. This implies failure of current therapeutic approaches based on renin-angiotensin system (RAS) blockade. Recent phase 3 clinical trials of paricalcitol in early diabetic kidney disease and bardoxolone methyl in advanced diabetic kidney disease failed to meet the primary endpoint or terminated on safety concerns, respectively. However, various novel strategies are undergoing phase 2 and 3 randomized controlled trials targeting inflammation, fibrosis and signaling pathways. Among agents currently undergoing trials that may modify the clinical practice on top of RAS blockade in a 5-year horizon, anti-inflammatory agents currently hold the most promise while anti-fibrotic agents have so far disappointed. Pentoxifylline, an anti-inflammatory agent already in clinical use, was recently reported to delay estimated glomerular filtration rate (eGFR) loss in chronic kidney disease (CKD) stage 3–4 diabetic kidney disease when associated with RAS blockade and promising phase 2 data are available for the pentoxifylline derivative CTP-499. Among agents targeting chemokines or chemokine receptors, the oral small molecule C-C chemokine receptor type 2 (CCR2) inhibitor CCX140 decreased albuminuria and eGFR loss in phase 2 trials. A dose-finding trial of the anti-IL-1β antibody gevokizumab in diabetic kidney disease will start in 2015. However, clinical development is most advanced for the endothelin receptor A blocker atrasentan, which is undergoing a phase 3 trial with a primary outcome of preserving eGFR. The potential for success of these approaches and other pipeline agents is discussed in detail. PMID:26239562

Angiopoietin receptor Tie2 is required for vein specification and maintenance via regulating COUP-TFII.

PubMed

Chu, Man; Li, Taotao; Shen, Bin; Cao, Xudong; Zhong, Haoyu; Zhang, Luqing; Zhou, Fei; Ma, Wenjuan; Jiang, Haijuan; Xie, Pancheng; Liu, Zhengzheng; Dong, Ningzheng; Xu, Ying; Zhao, Yun; Xu, Guoqiang; Lu, Peirong; Luo, Jincai; Wu, Qingyu; Alitalo, Kari; Koh, Gou Young; Adams, Ralf H; He, Yulong

2016-12-22

Mechanisms underlying the vein development remain largely unknown. Tie2 signaling mediates endothelial cell (EC) survival and vascular maturation and its activating mutations are linked to venous malformations. Here we show that vein formation are disrupted in mouse skin and mesentery when Tie2 signals are diminished by targeted deletion of Tek either ubiquitously or specifically in embryonic ECs. Postnatal Tie2 attenuation resulted in the degeneration of newly formed veins followed by the formation of haemangioma-like vascular tufts in retina and venous tortuosity. Mechanistically, Tie2 insufficiency compromised venous EC identity, as indicated by a significant decrease of COUP-TFII protein level, a key regulator in venogenesis. Consistently, angiopoietin-1 stimulation increased COUP-TFII in cultured ECs, while Tie2 knockdown or blockade of Tie2 downstream PI3K/Akt pathway reduced COUP-TFII which could be reverted by the proteasome inhibition. Together, our results imply that Tie2 is essential for venous specification and maintenance via Akt mediated stabilization of COUP-TFII.

LeEix1 functions as a decoy receptor to attenuate LeEix2 signaling.

PubMed

Bar, Maya; Sharfman, Miya; Avni, Adi

2011-03-01

The receptors for the fungal elicitor EIX (LeEix1 and LeEix2) belong to a class of leucine-rich repeat cell-surface glycoproteins with a signal for receptor-mediated endocytosis. Both receptors are able to bind the EIX elicitor while only the LeEix2 receptor mediates defense responses. We show that LeEix1 acts as a decoy receptor and attenuates EIX induced internalization and signaling of the LeEix2 receptor. We demonstrate that BAK1 binds LeEix1 but not LeEix2. In plants where BAK1 was silenced, LeEix1 was no longer able to attenuate plant responses to EIX, indicating that BAK1 is required for this attenuation. We suggest that LeEix1 functions as a decoy receptor for LeEix2, a function which requires the kinase activity of BAK1.

Presynaptic facilitatory adenosine A2A receptors mediate fade induced by neuromuscular relaxants that exhibit anticholinesterase activity.

PubMed

Bornia, Elaine Cs; Correia-de-Sá, Paulo; Alves-Do-Prado, Wilson

2011-03-01

1. Pancuronium, cisatracurium and vecuronium are antinicotinic agents that, in contrast with d-tubocurarine and hexamethonium, exhibit anticholinesterase activity. Pancuronium-, cisatracurium- and vecuronium-induced fade results from blockade of facilitatory nicotinic receptors on motor nerves, but fade produced by such agents also depends on the presynaptic activation of inhibitory muscarinic M2 receptors by acetylcholine released from motor nerve terminals and activation of inhibitory adenosine A1 receptors by adenosine released from motor nerves and muscles. The participation of presynaptic facilitatory A2A receptors in fade caused by pancuronium, cisatracurium and vecuronium has not yet been investigated. In the present study, we determined the effects of ZM241385, an antagonist of presynaptic facilitatory A2A receptors, on fade produced by these neuromuscular relaxants in the rat phrenic nerve-diaphragm (PND) preparation. 2. The muscles were stimulated indirectly at 75±3Hz to induce a sustained tetanizing muscular contraction. The lowest concentration at which each antinicotinic agent produced fade without modifying initial tetanic tension (presynaptic action) was determined. 3. d-Tubocurarine-induced fade occurred only at 55 nmol/L, a concentration that also reduced maximal tetanic tension (post-synaptic action). At 10 nmol/L, ZM 241385 alone did not produce fade, but it did attenuate pancuronium (0.32 μmol/L)-, cisatracurium (0.32 μmol/L)- and vecuronium (0.36 μmol/L)-induced fade. 4. The fade induced by the 'pure' antinicotinic agents d-tubocurarine (55 nmol/L) and hexamethonium (413 μmol/L) was not altered by 10 nmol/L ZM 241385, indicating that presynaptic adenosine A2A receptors play a significant role in the fade produced by antinicotinic agents when such agents have anticholinesterase activity. © 2011 The Authors. Clinical and Experimental Pharmacology and Physiology © 2011 Blackwell Publishing Asia Pty Ltd.

VEGF-Trap: a VEGF blocker with potent antitumor effects.

PubMed

Holash, Jocelyn; Davis, Sam; Papadopoulos, Nick; Croll, Susan D; Ho, Lillian; Russell, Michelle; Boland, Patricia; Leidich, Ray; Hylton, Donna; Burova, Elena; Ioffe, Ella; Huang, Tammy; Radziejewski, Czeslaw; Bailey, Kevin; Fandl, James P; Daly, Tom; Wiegand, Stanley J; Yancopoulos, George D; Rudge, John S

2002-08-20

Vascular endothelial growth factor (VEGF) plays a critical role during normal embryonic angiogenesis and also in the pathological angiogenesis that occurs in a number of diseases, including cancer. Initial attempts to block VEGF by using a humanized monoclonal antibody are beginning to show promise in human cancer patients, underscoring the importance of optimizing VEGF blockade. Previous studies have found that one of the most effective ways to block the VEGF-signaling pathway is to prevent VEGF from binding to its normal receptors by administering decoy-soluble receptors. The highest-affinity VEGF blocker described to date is a soluble decoy receptor created by fusing the first three Ig domains of VEGF receptor 1 to an Ig constant region; however, this fusion protein has very poor in vivo pharmacokinetic properties. By determining the requirements to maintain high affinity while extending in vivo half life, we were able to engineer a very potent high-affinity VEGF blocker that has markedly enhanced pharmacokinetic properties. This VEGF-Trap effectively suppresses tumor growth and vascularization in vivo, resulting in stunted and almost completely avascular tumors. VEGF-Trap-mediated blockade may be superior to that achieved by other agents, such as monoclonal antibodies targeted against the VEGF receptor.

Differential control of MMP and t-PA/PAI-1 expressions by sympathetic and renin-angiotensin systems in rat left ventricle.

PubMed

Dab, Houcine; Hachani, Rafik; Hodroj, Wassim; Sakly, Mohsen; Bricca, Giampiero; Kacem, Kamel

2009-10-05

In the present study, we tested the hypothesis that angiotensin II (Ang II) has both direct (via AT1 receptors) and indirect (via sympathostimulator pathway) actions on the synthesis and activity of the enzymes involved in the extracellular matrix degradation in vivo. For this purpose, sympathectomy and blockade of the Ang II receptor AT1 were performed alone or in combination in normotensive rats. The mRNA of the plasminogen activator (t-PA) and its inhibitor (PAI-1), the mRNA, protein and activity of the matrix metalloproteinases MMP-2 and MMP-9 were examined by Q-RT-PCR, immunoblotting and zymographic methods in the left ventricle. t-PA and PAI-1 mRNA were decreased after sympathectomy and remained unchanged after AT1 receptors blockade. mRNA was increased for t-PA and decreased by similar degree for PAI-1 after double treatment. MMPs mRNA and protein levels were decreased either after sympathectomy or AT1 receptors blockade and an additive effect was acquired after double treatment. MMPs activity was decreased by similar degree in the three treated groups. Deducted interpretations from our experimental approach suggest that Ang II inhibits directly (via AT1 receptors) and indirectly (via sympathostimulator pathway) t-PA mRNA synthesis. It seems unable to influence directly PAI-1 mRNA, but stimulates indirectly PAI-1 mRNA synthesis. Ang II stimulates directly (via AT1 receptors) and indirectly (via sympathostimulator pathway) MMPs synthesis at both transcriptional and protein levels. The enzymatic activity of MMPs does not seem to be influenced directly by Ang II but it could be stimulated indirectly (via sympathostimulator pathway).

Inhibition of non-NMDA ionotropic glutamate receptors delays the retinal degeneration in rd10 mouse.

PubMed

Xiang, Zongqin; Bao, Yiqin; Zhang, Jia; Liu, Chao; Xu, Di; Liu, Feng; Chen, Hui; He, Liumin; Ramakrishna, Seeram; Zhang, Zaijun; Vardi, Noga; Xu, Ying

2018-06-22

Retinitis pigmentosa (RP) is a hereditary blinding disease characterized by neurodegeneration of photoreceptors. Retinal ganglion cells (RGCs) in animal models of RP exhibit an abnormally high spontaneous activity that interferes with signal processing. Blocking AMPA/Kainate receptors by bath application of CNQX decreases the spontaneous firing, suggesting that inhibiting these receptors in vivo may help maintain the function of inner retinal neurons in rd10 mice experiencing photoreceptor degeneration. To test this, rd10 mice were i.p. injected with CNQX or GYKI 52466 (an AMPA receptor antagonist) for 1-2 weeks, and examined for their retinal morphology (by immunocytochemistry), function (by MEA recordings) and visual behaviors (using a black/white box). Our data show that iGluRs were up-regulated in the inner plexiform layer (IPL) of rd10 retinas. Application of CNQX at low doses both in vitro and in vivo, attenuated the abnormal spontaneous spiking in RGCs, and increased the light-evoked response of ON RGCs, whereas GYKI 52466 had little effect. CNQX application also improved the behavioral performance. Interestingly, in vivo administration of CNQX delayed photoreceptor degeneration, evidenced by the increased cell number and restored structure. CNQX also improved the structure of bipolar cells. Together, we demonstrated that during photoreceptor degeneration, blockade of the non-NMDA iGluRs decelerates the progression of RGCs dysfunction, possibly by dual mechanisms including slowing photoreceptor degeneration and modulating signal processing within the IPL. Accordingly, this strategy may effectively extend the time window for treating RP. Copyright © 2018. Published by Elsevier Ltd.

Redistribution of blood within the body is important for thermoregulation in an ectothermic vertebrate (Crocodylus porosus).

PubMed

Seebacher, Frank; Franklin, Craig E

2007-11-01

Changes in blood flow are a principal mechanism of thermoregulation in vertebrates. Changes in heart rate will alter blood flow, although multiple demands for limited cardiac output may compromise effective thermoregulation. We tested the hypothesis that regional differences in blood flow during heating and cooling can occur independently from changes in heart rate. We measured heart rate and blood pressure concurrently with blood flow in the crocodile, Crocodylus porosus. We measured changes in blood flow by laser Doppler flowmetry, and by injecting coloured microspheres. All measurements were made under different heat loads, with and without blocking cholinergic and beta-adrenergic receptors (autonomic blockade). Heart rates were significantly faster during heating than cooling in the control animals, but not when autonomic receptors were blocked. There were no significant differences in blood flow distribution between the control and autonomic blockade treatments. In both treatments, blood flow was directed to the dorsal skin and muscle and away from the tail and duodenum during heating. When the heat source was switched off, there was a redistribution of blood from the dorsal surface to the duodenum. Blood flow to the leg skin and muscle, and to the liver did not change significantly with thermal state. Blood pressure was significantly higher during the autonomic blockade than during the control. Thermal time constants of heating and cooling were unaffected by the blockade of autonomic receptors. We concluded that animals partially compensated for a lack of differential heart rates during heating and cooling by redistributing blood within the body, and by increasing blood pressure to increase flow. Hence, measures of heart rate alone are insufficient to assess physiological thermoregulation in reptiles.

The gut-brain axis rewired: adding a functional vagal nicotinic "sensory synapse".

PubMed

Perez-Burgos, Azucena; Mao, Yu-Kang; Bienenstock, John; Kunze, Wolfgang A

2014-07-01

It is generally accepted that intestinal sensory vagal fibers are primary afferent, responding nonsynaptically to luminal stimuli. The gut also contains intrinsic primary afferent neurons (IPANs) that respond to luminal stimuli. A psychoactive Lactobacillus rhamnosus (JB-1) that affects brain function excites both vagal fibers and IPANs. We wondered whether, contrary to its primary afferent designation, the sensory vagus response to JB-1 might depend on IPAN to vagal fiber synaptic transmission. We recorded ex vivo single- and multiunit afferent action potentials from mesenteric nerves supplying mouse jejunal segments. Intramural synaptic blockade with Ca(2+) channel blockers reduced constitutive or JB-1-evoked vagal sensory discharge. Firing of 60% of spontaneously active units was reduced by synaptic blockade. Synaptic or nicotinic receptor blockade reduced firing in 60% of vagal sensory units that were stimulated by luminal JB-1. In control experiments, increasing or decreasing IPAN excitability, respectively increased or decreased nerve firing that was abolished by synaptic blockade or vagotomy. We conclude that >50% of vagal afferents function as interneurons for stimulation by JB-1, receiving input from an intramural functional "sensory synapse." This was supported by myenteric plexus nicotinic receptor immunohistochemistry. These data offer a novel therapeutic target to modify pathological gut-brain axis activity.-Perez-Burgos, A., Mao, Y.-K., Bienenstock, J., Kunze, W. A. The gut-brain axis rewired: adding a functional vagal nicotinic "sensory synapse." © FASEB.

Immune checkpoints PVR and PVRL2 are prognostic markers in AML and their blockade represents a new therapeutic option.

PubMed

Stamm, Hauke; Klingler, Felix; Grossjohann, Eva-Maria; Muschhammer, Jana; Vettorazzi, Eik; Heuser, Michael; Mock, Ulrike; Thol, Felicitas; Vohwinkel, Gabi; Latuske, Emily; Bokemeyer, Carsten; Kischel, Roman; Dos Santos, Cedric; Stienen, Sabine; Friedrich, Matthias; Lutteropp, Michael; Nagorsen, Dirk; Wellbrock, Jasmin; Fiedler, Walter

2018-05-31

Immune checkpoints are promising targets in cancer therapy. Recently, poliovirus receptor (PVR) and poliovirus receptor-related 2 (PVRL2) have been identified as novel immune checkpoints. In this investigation we show that acute myeloid leukemia (AML) cell lines and AML patient samples highly express the T-cell immunoreceptor with Ig and ITIM domains (TIGIT) ligands PVR and PVRL2. Using two independent patient cohorts, we could demonstrate that high PVR and PVRL2 expression correlates with poor outcome in AML. We show for the first time that antibody blockade of PVR or PVRL2 on AML cell lines or primary AML cells or TIGIT blockade on immune cells increases the anti-leukemic effects mediated by PBMCs or purified CD3 + cells in vitro. The cytolytic activity of the BiTE® antibody construct AMG 330 against leukemic cells could be further enhanced by blockade of the TIGIT-PVR/PVRL2 axis. This increased immune reactivity is paralleled by augmented secretion of Granzyme B by immune cells. Employing CRISPR/Cas9-mediated knockout of PVR and PVRL2 in MV4-11 cells, the cytotoxic effects of antibody blockade could be recapitulated in vitro. In NSG mice reconstituted with human T cells and transplanted with either MV4-11 PVR/PVRL2 knockout or wildtype cells, prolonged survival was observed for the knockout cells. This survival benefit could be further extended by treating the mice with AMG 330. Therefore, targeting the TIGIT-PVR/PVRL2 axis with blocking antibodies might represent a promising future therapeutic option in AML.

Oxidative activation of CaMKIIδ in acute myocardial ischemia/reperfusion injury: A role of angiotensin AT1 receptor-NOX2 signaling axis.

PubMed

Rajtik, Tomas; Carnicka, Slavka; Szobi, Adrian; Giricz, Zoltan; O-Uchi, Jin; Hassova, Veronika; Svec, Pavel; Ferdinandy, Peter; Ravingerova, Tanya; Adameova, Adriana

2016-01-15

During ischemia/reperfusion (IR), increased activation of angiotensin AT1 receptors recruits NADPH oxidase 2 (NOX2) which contributes to oxidative stress. It is unknown whether this stimulus can induce oxidative activation of Ca(2+)/calmodulin-dependent protein kinase IIδ (CaMKIIδ) leading into the aggravation of cardiac function and whether these effects can be prevented by angiotensin AT1 receptors blockade. Losartan, a selective AT1 blocker, was used. Its effects were compared with effects of KN-93, an inhibitor of CaMKIIδ. Global IR was induced in Langendorff-perfused rat hearts. Protein expression was evaluated by immunoblotting and lipoperoxidation was measured by TBARS assay. Losartan improved LVDP recovery by 25%; however, it did not reduce reperfusion arrhythmias. Oxidized CaMKIIδ (oxCaMKIIδ) was downregulated at the end of reperfusion compared to before ischemia and losartan did not change these levels. Phosphorylation of CaMKIIδ mirrored the pattern of changes in oxCaMKIIδ levels. Losartan did not prevent the higher lipoperoxidation due to IR and did not influence NOX2 expression. Inhibition of CaMKII ameliorated cardiac IR injury; however, this was not accompanied with changes in the levels of either active form of CaMKIIδ in comparison to the angiotensin AT1 receptor blockade. In spite of no changes of oxCaMKIIδ, increased cardiac recovery of either therapy was abolished when combined together. This study showed that oxidative activation of CaMKIIδ is not elevated at the end of R phase. NOX2-oxCAMKIIδ signaling is unlikely to be involved in cardioprotective action of angiotensin AT1 receptor blockade which is partially abolished by concomitant CaMKII inhibition. Copyright © 2015 Elsevier B.V. All rights reserved.

Peristalsis and propulsion of colonic content can occur after blockade of major neuroneuronal and neuromuscular transmitters in isolated guinea pig colon.

PubMed

Sia, T C; Brookes, S J; Dinning, P G; Wattchow, D A; Spencer, N J

2013-12-01

We recently identified hexamethonium-resistant peristalsis in the guinea pig colon. We showed that, following acute blockade of nicotinic receptors, peristalsis recovers, leading to normal propagation velocities of fecal pellets along the colon. This raises the fundamental question: what mechanisms underlie hexamethonium-resistant peristalsis? We investigated whether blockade of the major receptors that underlie excitatory neuromuscular transmission is required for hexamethonium-resistant peristalsis. Video imaging of colonic wall movements was used to make spatiotemporal maps and determine the velocity of peristalsis. Propagation of artificial fecal pellets in the guinea pig distal colon was studied in hexamethonium, atropine, ω-conotoxin (GVIA), ibodutant (MEN-15596), and TTX. Hexamethonium and ibodutant alone did not retard peristalsis. In contrast, ω-conotoxin abolished peristalsis in some preparations and reduced the velocity of propagation in all remaining specimens. Peristalsis could still occur in some animals in the presence of hexamethonium + atropine + ibodutant + ω-conotoxin. Peristalsis never occurred in the presence of TTX. The major finding of the current study is the unexpected observation that peristalsis can occur after blockade of the major excitatory neuroneuronal and neuromuscular transmitters. Also, the colon retained an intrinsic polarity in the presence of these antagonists and was only able to expel pellets in an aboral direction. The nature of the mechanism(s)/neurotransmitter(s) that generate(s) peristalsis and facilitate(s) natural fecal pellet propulsion, after blockade of major excitatory neurotransmitters, at the neuroneuronal and neuromuscular junction remains to be identified.

Smoking-associated lung cancer prevention by blockade of the beta-adrenergic receptor-mediated insulin-like growth factor receptor activation.

PubMed

Min, Hye-Young; Boo, Hye-Jin; Lee, Ho Jin; Jang, Hyun-Ji; Yun, Hye Jeong; Hwang, Su Jung; Smith, John Kendal; Lee, Hyo-Jong; Lee, Ho-Young

2016-10-25

Activation of receptor tyrosine kinases (RTKs) is associated with carcinogenesis, but its contribution to smoking-associated lung carcinogenesis is poorly understood. Here we show that a tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced insulin-like growth factor 1 receptor (IGF-1R) activation via β-adrenergic receptor (β-AR) is crucial for smoking-associated lung carcinogenesis. Treatment with NNK stimulated the IGF-1R signaling pathway in a time- and dose-dependent manner, which was suppressed by pharmacological or genomic blockade of β-AR and the downstream signaling including a Gβγ subunit of β-AR and phospholipase C (PLC). Consistently, β-AR agonists led to increased IGF-1R phosphorylation. The increase in IGF2 transcription via β-AR, signal transducer and activator of transcription 3 (STAT3), and nuclear factor-kappa B (NF-κB) was associated with NNK-induced IGF-1R activation. Finally, treatment with β-AR antagonists suppressed the acquisition of transformed phenotypes in lung epithelial cells and lung tumor formation in mice. These results suggest that blocking β-AR-mediated IGF-1R activation can be an effective strategy for lung cancer prevention in smokers.

Prolonged Exposure to NMDAR Antagonist Induces Cell-type Specific Changes of Glutamatergic Receptors in Rat Prefrontal Cortex

PubMed Central

Wang, Huai-Xing; Gao, Wen-Jun

2011-01-01

N-methyl-D-aspartic acid (NMDA) receptors are critical for both normal brain functions and the pathogenesis of schizophrenia. We investigated the functional changes of glutamatergic receptors in the pyramidal cells and fast-spiking (FS) interneurons in the adolescent rat prefrontal cortex in MK-801 model of schizophrenia. We found that although both pyramidal cells and FS interneurons were affected by in vivo subchronic blockade of NMDA receptors, MK-801 induced distinct changes in αamino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and NMDA receptors in the FS interneurons compared with pyramidal cells. Specifically, the amplitude, but not the frequency, of AMPA-mediated miniature excitatory postsynaptic currents (mEPSCs) in FS interneurons was significantly decreased whereas both the frequency and amplitude in pyramidal neurons were increased. In addition, MK-801-induced new presynaptic NMDA receptors were detected in the glutamatergic terminals targeting pyramidal neurons but not FS interneurons. MK-801 also induced distinct alterations in FS interneurons but not in pyramidal neurons, including significantly decreased rectification index and increased calcium permeability. These data suggest a distinct cell-type specific and homeostatic synaptic scaling and redistribution of AMPA and NMDA receptors in response to the subchronic blockade of NMDA receptors and thus provide a direct mechanistic explanation for the NMDA hypofunction hypothesis that have long been proposed for the schizophrenia pathophysiology. PMID:22182778

Blockade of adenosine A2A receptor enhances CD8+ T cells response and decreases regulatory T cells in head and neck squamous cell carcinoma.

PubMed

Ma, Si-Rui; Deng, Wei-Wei; Liu, Jian-Feng; Mao, Liang; Yu, Guang-Tao; Bu, Lin-Lin; Kulkarni, Ashok B; Zhang, Wen-Feng; Sun, Zhi-Jun

2017-06-07

Cancer immunotherapy offers a promising approach in cancer treatment. The adenosine A2A receptor (A2AR) could protect cancerous tissues from immune clearance via inhibiting T cells response. To date, the role of A2AR in head and neck squamous cell carcinoma (HNSCC) has not been investigated. Here, we sought to explore the expression and immunotherapeutic value of A2AR blockade in HNSCC. The expression of A2AR was evaluated by immunostaining in 43 normal mucosae, 48 dysplasia and 165 primary HNSCC tissues. The immunotherapeutic value of A2AR blockade was assessed in vivo in genetically defined immunocompetent HNSCC mouse model. Immunostaining of HNSCC tissue samples revealed that increased expression of A2AR on tumor infiltrating immune cells correlated with advanced pathological grade, larger tumor size and positive lymph node status. Elevated A2AR expression was also detected in recurrent HNSCC and HNSCC tissues with induction chemotherapy. The expression of A2AR was found to be significantly correlated with HIF-1α, CD73, CD8 and Foxp3. Furthermore, the increased population of CD4 + Foxp3 + regulatory T cells (Tregs), which partially expressed A2AR, was observed in an immunocompetent mouse model that spontaneously develops HNSCC. Pharmacological blockade of A2AR by SCH58261 delayed the tumor growth in the HNSCC mouse model. Meanwhile, A2AR blockade significantly reduced the population of CD4 + Foxp3 + Tregs and enhanced the anti-tumor response of CD8 + T cells. These results offer a preclinical proof for the administration of A2AR inhibitor on prophylactic experimental therapy of HNSCC and suggest that A2AR blockade can be a potential novel strategy for HNSCC immunotherapy.

A randomized trial on mineralocorticoid receptor blockade in men: effects on stress responses, selective attention, and memory.

PubMed

Cornelisse, Sandra; Joëls, Marian; Smeets, Tom

2011-12-01

Corticosteroids, released in high amounts after stress, exert their effects via two different receptors in the brain: glucocorticoid receptors (GRs) and mineralocorticoid receptors (MRs). GRs have a role in normalizing stress-induced effects and promoting consolidation, while MRs are thought to be important in determining the threshold for activation of the hypothalamic-pituitary-adrenal (HPA) axis. We investigated the effects of MR blockade on HPA axis responses to stress and stress-induced changes in cognitive function. In a double-blind, placebo-controlled study, 64 healthy young men received 400 mg of the MR antagonist spironolactone or placebo. After 1.5 h, they were exposed to either a Trier Social Stress Test or a non-stressful control task. Responses to stress were evaluated by hormonal, subjective, and physiological measurements. Afterwards, selective attention, working memory, and long-term memory performance were assessed. Spironolactone increased basal salivary cortisol levels as well as cortisol levels in response to stress. Furthermore, spironolactone significantly impaired selective attention, but only in the control group. The stress group receiving spironolactone showed impaired working memory performance. By contrast, long-term memory was enhanced in this group. These data support a role of MRs in the regulation of the HPA axis under basal conditions as well as in response to stress. The increased availability of cortisol after spironolactone treatment implies enhanced GR activation, which, in combination with MR blockade, presumably resulted in a decreased MR/GR activation ratio. This condition influences both selective attention and performance in various memory tasks.

TRPV1 receptor-mediated expression of Toll-like receptors 2 and 4 following permanent middle cerebral artery occlusion in rats

PubMed Central

Hakimizadeh, Elham; Shamsizadeh, Ali; Roohbakhsh, Ali; Arababadi, Mohammad Kazemi; Hajizadeh, Mohammad Reza; Shariati, Mehdi; Fatemi, Iman; Moghadam-ahmadi, Amir; Bazmandegan, Gholamreza; Rezazadeh, Hossein; Allahtavakoli, Mohammad

2017-01-01

Objective(s): Stroke is known as a main cause of mortality and prolonged disability in adults. Both transient receptor potential V1 (TRPV1) channels and toll-like receptors (TLRs) are involved in mediating the inflammatory responses. In the present study, the effects of TRPV1 receptor activation and blockade on stroke outcome and gene expression of TLR2 and TLR4 were assessed following permanent middle cerebral artery occlusion in rats Materials and Methods: Eighty male Wistar rats were divided into four groups as follows: sham, vehicle, AMG9810 (TRPV1 antagonist) -treated and capsaicin (TRPV1 agonist) -treated. For Stroke induction, the middle cerebral artery was permanently occluded and then behavioral functions were evaluated 1, 3 and 7 days after stroke. Results: TRPV1 antagonism significantly reduced the infarct volume compared to the stroke group. Also, neurological deficits were decreased by AMG9810 seven days after cerebral ischemia. In the ledged beam-walking test, the slip ratio was enhanced following ischemia. AMG9810 decreased this index in stroke animals. However, capsaicin improved the ratio 3 and 7 days after cerebral ischemia. Compared to the sham group, the mRNA expression of TLR2 and TLR4 was significantly increased in the stroke rats. AMG9810 Administration significantly reduced the mRNA expression of TLR2 and TLR4. However, capsaicin did not significantly affect the gene expression of TLR2 and TLR4. Conclusion: Our results demonstrated that TRPV1 antagonism by AMG9810 attenuates behavioral function and mRNA expression of TLR2 and TLR4. Thus, it might be useful to shed light on future therapeutic strategies for the treatment of ischemic stroke. PMID:29085577

Inhibition of Hippocampal β-Adrenergic Receptors Impairs Retrieval But Not Reconsolidation of Cocaine-Associated Memory and Prevents Subsequent Reinstatement

PubMed Central

Otis, James M; Fitzgerald, Michael K; Mueller, Devin

2014-01-01

Retrieval of drug-associated memories is critical for maintaining addictive behaviors, as presentation of drug-associated cues can elicit drug seeking and relapse. Recently, we and others have demonstrated that β-adrenergic receptor (β-AR) activation is necessary for retrieval using both rat and human memory models. Importantly, blocking retrieval with β-AR antagonists persistently impairs retrieval and provides protection against subsequent reinstatement. However, the neural locus at which β-ARs are required for maintaining retrieval and subsequent reinstatement is unclear. Here, we investigated the necessity of dorsal hippocampus (dHipp) β-ARs for drug-associated memory retrieval. Using a cocaine conditioned place preference (CPP) model, we demonstrate that local dHipp β-AR blockade before a CPP test prevents CPP expression shortly and long after treatment, indicating that dHipp β-AR blockade induces a memory retrieval disruption. Furthermore, this retrieval disruption provides long-lasting protection against cocaine-induced reinstatement. The effects of β-AR blockade were dependent on memory reactivation and were not attributable to reconsolidation disruption as blockade of β-ARs immediately after a CPP test had little effect on subsequent CPP expression. Thus, cocaine-associated memory retrieval is mediated by β-AR activity within the dHipp, and disruption of this activity could prevent cue-induced drug seeking and relapse long after treatment. PMID:23907403

Inhibition of hippocampal β-adrenergic receptors impairs retrieval but not reconsolidation of cocaine-associated memory and prevents subsequent reinstatement.

PubMed

Otis, James M; Fitzgerald, Michael K; Mueller, Devin

2014-01-01

Retrieval of drug-associated memories is critical for maintaining addictive behaviors, as presentation of drug-associated cues can elicit drug seeking and relapse. Recently, we and others have demonstrated that β-adrenergic receptor (β-AR) activation is necessary for retrieval using both rat and human memory models. Importantly, blocking retrieval with β-AR antagonists persistently impairs retrieval and provides protection against subsequent reinstatement. However, the neural locus at which β-ARs are required for maintaining retrieval and subsequent reinstatement is unclear. Here, we investigated the necessity of dorsal hippocampus (dHipp) β-ARs for drug-associated memory retrieval. Using a cocaine conditioned place preference (CPP) model, we demonstrate that local dHipp β-AR blockade before a CPP test prevents CPP expression shortly and long after treatment, indicating that dHipp β-AR blockade induces a memory retrieval disruption. Furthermore, this retrieval disruption provides long-lasting protection against cocaine-induced reinstatement. The effects of β-AR blockade were dependent on memory reactivation and were not attributable to reconsolidation disruption as blockade of β-ARs immediately after a CPP test had little effect on subsequent CPP expression. Thus, cocaine-associated memory retrieval is mediated by β-AR activity within the dHipp, and disruption of this activity could prevent cue-induced drug seeking and relapse long after treatment.

Acute stressor exposure modifies plasma exosome-associated heat shock protein 72 (Hsp72) and microRNA (miR-142-5p and miR-203).

PubMed

Beninson, Lida A; Brown, Peter N; Loughridge, Alice B; Saludes, Jonel P; Maslanik, Thomas; Hills, Abigail K; Woodworth, Tyler; Craig, Wendy; Yin, Hang; Fleshner, Monika

2014-01-01

Exosomes, biologically active nanoparticles (40-100 nm) released by hematopoietic and non-hematopoietic cells, contain a variety of proteins and small, non-coding RNA known as microRNA (miRNA). Exposure to various pathogens and disease states modifies the composition and function of exosomes, but there are no studies examining in vivo exosomal changes evoked by the acute stress response. The present study reveals that exposing male Fisher 344 rats to an acute stressor modulates the protein and miRNA profile of circulating plasma exosomes, specifically increasing surface heat shock protein 72 (Hsp72) and decreasing miR-142-5p and -203. The selected miRNAs and Hsp72 are associated with immunomodulatory functions and are likely a critical component of stress-evoked modulation of immunity. Further, we demonstrate that some of these stress-induced modifications in plasma exosomes are mediated by sympathetic nervous system (SNS) activation of alpha-1 adrenergic receptors (ADRs), since drug-mediated blockade of the receptors significantly attenuates the stress-induced modifications of exosomal Hsp72 and miR-142-5p. Together, these findings demonstrate that activation of the acute stress response modifies the proteomic and miRNA profile of exosomes released into the circulation.

Is the Acute NMDA Receptor Hypofunction a Valid Model of Schizophrenia?

PubMed Central

Adell, Albert; Jiménez-Sánchez, Laura; López-Gil, Xavier; Romón, Tamara

2012-01-01

Several genetic, neurodevelopmental, and pharmacological animal models of schizophrenia have been established. This short review examines the validity of one of the most used pharmacological model of the illness, ie, the acute administration of N-methyl-D-aspartate (NMDA) receptor antagonists in rodents. In some cases, data on chronic or prenatal NMDA receptor antagonist exposure have been introduced for comparison. The face validity of acute NMDA receptor blockade is granted inasmuch as hyperlocomotion and stereotypies induced by phencyclidine, ketamine, and MK-801 are regarded as a surrogate for the positive symptoms of schizophrenia. In addition, the loss of parvalbumin-containing cells (which is one of the most compelling finding in postmortem schizophrenia brain) following NMDA receptor blockade adds construct validity to this model. However, the lack of changes in glutamic acid decarboxylase (GAD67) is at variance with human studies. It is possible that changes in GAD67 are more reflective of the neurodevelopmental condition of schizophrenia. Finally, the model also has predictive validity, in that its behavioral and transmitter activation in rodents are responsive to antipsychotic treatment. Overall, although not devoid of drawbacks, the acute administration of NMDA receptor antagonists can be considered as a good model of schizophrenia bearing a satisfactory degree of validity. PMID:21965469

Human epidermal growth factor receptor bispecific ligand trap RB200: abrogation of collagen-induced arthritis in combination with tumour necrosis factor blockade

PubMed Central

2011-01-01

Introduction Rheumatoid arthritis (RA) is a chronic disease associated with inflammation and destruction of bone and cartilage. Although inhibition of TNFα is widely used to treat RA, a significant number of patients do not respond to TNFα blockade, and therefore there is a compelling need to continue to identify alternative therapeutic strategies for treating chronic inflammatory diseases such as RA. The anti-epidermal growth factor (anti-EGF) receptor antibody trastuzumab has revolutionised the treatment of patients with EGF receptor-positive breast cancer. Expression of EGF ligands and receptors (known as HER) has also been documented in RA. The highly unique compound RB200 is a bispecific ligand trap that is composed of full-length extracellular domains of HER1 and HER3 EGF receptors. Because of its pan-HER specificity, RB200 inhibits responses mediated by HER1, HER2 and HER3 in vitro and in vivo. The objective of this study was to assess the effect of RB200 combined with TNF blockade in a murine collagen-induced arthritis (CIA) model of RA. Methods Arthritic mice were treated with RB200 alone or in combination with the TNF receptor fusion protein etanercept. We performed immunohistochemistry to assess CD31 and in vivo fluorescent imaging using anti-E-selectin antibody labelled with fluorescent dye to elucidate the effect of RB200 on the vasculature in CIA. Results RB200 significantly abrogated CIA by reducing paw swelling and clinical scores. Importantly, low-dose RB200 combined with a suboptimal dose of etanercept led to complete abrogation of arthritis. Moreover, the combination of RB200 with etanercept abrogated the intensity of the E-selectin-targeted signal to the level seen in control animals not immunised to CIA. Conclusions The human pan-EGF receptor bispecific ligand trap RB200, when combined with low-dose etanercept, abrogates CIA, suggesting that inhibition of events downstream of EGF receptor activation, in combination with TNFα inhibitors, may hold promise as a future therapy for patients with RA. PMID:21982514

The effect of RAAS blockade on the progression of diabetic nephropathy.

PubMed

Roscioni, Sara S; Heerspink, Hiddo J Lambers; de Zeeuw, Dick

2014-02-01

The renin-angiotensin-aldosterone system (RAAS) has a key role in the regulation of blood pressure, sodium and water balance, and cardiovascular and renal homeostasis. In diabetic nephropathy, excessive activation of the RAAS results in progressive renal damage. RAAS blockade using angiotensin-converting-enzyme inhibitors or angiotensin-receptor blockers is the cornerstone of treatment of diabetic renal disease. Alternative RAAS-blockade strategies include renin inhibition and aldosterone blockade. Data from small initial studies of these agents are promising. However, single-agent interventions do not fully block the RAAS and patients treated with these therapies remain at high residual renal risk. Approaches to optimize drug responses include dietary changes and increasing dosages. The theoretically attractive option of combining different RAAS interventions has also been tested in clinical trials but long-term outcomes were disappointing. However, dual RAAS blockade might represent a good therapeutic option for specific patients. A better knowledge of the pathophysiology of the RAAS is crucial to fully understand the mechanisms of action of RAAS blockers and to exploit their renoprotective effects. Moreover, lifestyle interventions or diagnostic tools might be used to optimize RAAS blockade and identify those patients who are most likely to benefit from the therapy.

The hypocretin/orexin system mediates the extinction of fear memories.

PubMed

Flores, África; Valls-Comamala, Victòria; Costa, Giulia; Saravia, Rocío; Maldonado, Rafael; Berrendero, Fernando

2014-11-01

Anxiety disorders are often associated with an inability to extinguish learned fear responses. The hypocretin/orexin system is involved in the regulation of emotional states and could also participate in the consolidation and extinction of aversive memories. Using hypocretin receptor-1 and hypocretin receptor-2 antagonists, hypocretin-1 and hypocretin-2 peptides, and hypocretin receptor-1 knockout mice, we investigated the role of the hypocretin system in cue- and context-dependent fear conditioning and extinction. Hypocretins were crucial for the consolidation of fear conditioning, and this effect was mainly observed in memories with a high emotional component. Notably, after the acquisition of fear memory, hypocretin receptor-1 blockade facilitated fear extinction, whereas hypocretin-1 administration impaired this extinction process. The extinction-facilitating effects of the hypocretin receptor-1 antagonist SB334867 were associated with increased expression of cFos in the basolateral amygdala and the infralimbic cortex. Intra-amygdala, but neither intra-infralimbic prefrontal cortex nor intra-dorsohippocampal infusion of SB334867 enhanced fear extinction. These results reveal a key role for hypocretins in the extinction of aversive memories and suggest that hypocretin receptor-1 blockade could represent a novel therapeutic target for the treatment of diseases associated with inappropriate retention of fear, such as post-traumatic stress disorder and phobias.

The Hypocretin/Orexin System Mediates the Extinction of Fear Memories

PubMed Central

Flores, África; Valls-Comamala, Victòria; Costa, Giulia; Saravia, Rocío; Maldonado, Rafael; Berrendero, Fernando

2014-01-01

Anxiety disorders are often associated with an inability to extinguish learned fear responses. The hypocretin/orexin system is involved in the regulation of emotional states and could also participate in the consolidation and extinction of aversive memories. Using hypocretin receptor-1 and hypocretin receptor-2 antagonists, hypocretin-1 and hypocretin-2 peptides, and hypocretin receptor-1 knockout mice, we investigated the role of the hypocretin system in cue- and context-dependent fear conditioning and extinction. Hypocretins were crucial for the consolidation of fear conditioning, and this effect was mainly observed in memories with a high emotional component. Notably, after the acquisition of fear memory, hypocretin receptor-1 blockade facilitated fear extinction, whereas hypocretin-1 administration impaired this extinction process. The extinction-facilitating effects of the hypocretin receptor-1 antagonist SB334867 were associated with increased expression of cFos in the basolateral amygdala and the infralimbic cortex. Intra-amygdala, but neither intra-infralimbic prefrontal cortex nor intra-dorsohippocampal infusion of SB334867 enhanced fear extinction. These results reveal a key role for hypocretins in the extinction of aversive memories and suggest that hypocretin receptor-1 blockade could represent a novel therapeutic target for the treatment of diseases associated with inappropriate retention of fear, such as post-traumatic stress disorder and phobias. PMID:24930888

Beta blocker infusion decreases the magnitude of core hypothermia after anesthesia induction.

PubMed

Inoue, S; Abe, R; Kawaguchi, M; Kobayashi, H; Furuya, H

2010-12-01

Beta-1-receptor blockade reduces heart rate, cardiac output, and arterial pressure while increasing peripheral vascular resistance. It is possible that beta blockers not only inhibit the core-to-peripheral re-distribution of body heat and cutaneous heat loss due to vasodilation after anesthesia induction but also reduce the convective transfer of heat from the core to peripheral tissues by decreasing cardiac output. The authors investigated whether the co-administration of esmolol or landiolol, ultra-short-acting beta blockers, attenuates the magnitude of initial re-distribution hypothermia after anesthesia induction and tracheal intubation. Immediately prior to the induction of anesthesia, patients were randomly assigned to receive 0.2 mg kg-1 of landiolol (landiolol group; N=30), 1 mg kg-1 of esmolol (esmolol group; N=30), or 0.1 mL kg-1 of saline (control group; N=30). Heart rate, blood pressure, cardiac output, and tympanic, forearm, and digit temperatures were recorded. Forearm minus fingertip skin-surface temperature gradients (temperature gradient) were calculated. Tympanic membrane temperatures 15 to 60 min after the induction of anesthesia were significantly higher in the esmolol group than in the control group although the temperature gradient was similar among the three groups. Both esmolol and landiolol inhibited the increase in HR and MAP after the induction of anesthesia and tracheal intubation. The cardiac index in the esmolol group was significantly lower than in the control group. The degree of hemodynamic attenuation after induction by esmolol was larger than that of landiolol. The co-administration of esmolol, but not landiolol, attenuated the magnitude of initial re-distribution hypothermia after anesthesia induction and tracheal intubation. Esmolol likely prevented initial hypothermia because it attenuated the convective transfer of heat from the core to peripheral tissues by decreasing cardiac output.

The non-competitive blockade of GABAA receptors by an aqueous extract of water hemlock (Cicuta douglassi) tubers

USDA-ARS?s Scientific Manuscript database

Teratogenic alkaloids can cause developmental defects due to the inhibition of fetal movement from the desensitization of fetal muscle-type nicotinic acetylcholine receptors (nAChR). In this study, we tested the hypothesis that the piperidine alkaloid anabaseine a 1,2-dehydropiperidine and anabasin...

A Comparison of Behavioral and Pharmacological Interventions to Attenuate Reactivated Fear Memories

ERIC Educational Resources Information Center

Monti, Roque I. Ferrer; Alfei, Joaquin M.; Mugnaini, Matias; Bueno, Adrian M.; Beckers, Tom; Urcelay, Gonzalo P.; Molina, Victor A.

2017-01-01

Two experiments using rats in a contextual fear memory preparation compared two approaches to reduce conditioned fear: (1) pharmacological reconsolidation blockade and (2) reactivation-plus-extinction training. In Experiment 1, we explored different combinations of reactivation-plus-extinction parameters to reduce conditioned fear and attenuate…

Multiple functions of GABA A and GABA B receptors during pattern processing in the zebrafish olfactory bulb.

PubMed

Tabor, Rico; Yaksi, Emre; Friedrich, Rainer W

2008-07-01

gamma-Aminobutyric acid (GABA)ergic synapses are thought to play pivotal roles in the processing of activity patterns in the olfactory bulb (OB), but their functions have been difficult to study during odor responses in the intact system. We pharmacologically manipulated GABA(A) and GABA(B) receptors in the OB of zebrafish and analysed the effects on odor responses of the output neurons, the mitral cells (MCs), by electrophysiological recordings and temporally deconvolved two-photon Ca2+ imaging. The blockade of GABA(B) receptors enhanced presynaptic Ca2+ influx into afferent axon terminals, and changed the amplitude and time course of a subset of MC responses, indicating that GABA(B) receptors have a modulatory influence on OB output activity. The blockade of GABA(A) receptors induced epileptiform firing, enhanced excitatory responses and abolished fast oscillations in the local field potential. Moreover, the topological reorganization and decorrelation of MC activity patterns during the initial phase of the response was perturbed. These results indicate that GABA(A) receptor-containing circuits participate in the balance of excitation and inhibition, the regulation of total OB output activity, the synchronization of odor-dependent neuronal ensembles, and the reorganization of odor-encoding activity patterns. GABA(A) and GABA(B) receptors are therefore differentially involved in multiple functions of neuronal circuits in the OB.

[STUDYING THE ROLE OF BRAIN MELANOCORTIN RECEPTORS IN THE SUPPRESSING OF FOOD INTAKE UNDER ETHER STRESS IN MICE].

PubMed

Bazhan, N M; Kulikova, E V; Makarova, E N; Yakovleva, T V; Kazantseva, A Yu

2015-12-01

Melanocortin (MC) system regulates food intake under the rest conditions. Stress inhibits food intake. It is not clear whether brain MC system is involved in stress-induced anorexia in mice. The aim of the work was to investigate the effect of pharmacological blockade and activation of brain MC receptors on food intake under stress. C57B1/6J male mice were subjected to ether stress (0.5 minute ether anesthesia) before the administration of saline solution or synthetic non-selective blocker (SHU9119) or agonist (Melanotan II) of MC receptors into the lateral brain ventricle. Food intake was pre-stimulated with 17 hours of fasting in all mice. Ether stress decreased food intake, increased the plasma corticosterone level and hypothalamic mRNA AgRP (natural MC receptor antagonist) level at 1 hour after the stress. Pharmacological blockade of the MC receptors weakened stress-induced anorexia and decreased mRNA AgRP level in the hypothalamus. Pharmacological stimulation of the MC receptors enhanced ether stress-induced anorexia and hypercortisolism. Thus, our data demonstrated that the central MC system was involved in the development of stress-induced anorexia in mice.

Cannabinoid 1 receptor blockade in the dorsal hippocampus prevents the reinstatement but not acquisition of morphine-induced conditioned place preference in rats.

PubMed

Zhao, Xin; Yao, Li; Wang, Fang; Zhang, Han; Wu, Li

2017-07-05

The cannabinoid 1 receptors (CB1Rs) signaling is strongly linked to conditioned rewarding effects of opiates. Learned associations between environmental contexts and discrete cues and drug use play an important role in the maintenance and/or relapse of morphine addiction. Although previous studies suggest that context-dependent morphine treatment alters endocannabinoid signaling and synaptic plasticity in the hippocampus, the role of endocannabinoid in morphine conditioned place preference (CPP) and reinstatement remains unknown. In the present study, we found daily escalating doses of morphine induce significant CPP in rats. After the extinction of CPP, a priming dose of morphine was sufficient to reinstate morphine CPP and was associated with the elevated CB1R levels compared with saline control groups, suggesting upregulation of CB1R pathway in the hippocampus contribute to the reinstatement of morphine CPP. By using a pharmacological inhibitor of CB1R administered into the dorsal hippocampus, we showed that blockade of CB1R signaling did not alter the morphine CPP acquisition but inhibited the reinstatement of morphine CPP. In addition, no effects were induced upon CB1R blockade in the prefrontal cortex on reinstatement of morphine CPP. These studies reveal region-specific effects of hippocampal blockade of CB1R signaling pathway on the reinstatement of morphine CPP.

Vestibulo-oculomotor behaviour in rats following a transient unilateral vestibular loss induced by lidocaine.

PubMed

Magnusson, A K; Tham, R

2003-01-01

The effects of a transient vestibular nerve blockade, achieved by intra-tympanic instillation of lidocaine, were studied in rats by recording horizontal eye movements in darkness. Evaluation of the dose-response relationship showed that a maximal effect was attained with a concentration of 4% lidocaine. Within 15 min of lidocaine instillation, a vigorous spontaneous nystagmus was observed which reached maximal frequency and velocity of the slow phase after about 20 min. Subsequently, the nystagmus failed for approximately half an hour before it reappeared. This could be avoided by providing visual feedback in between the recordings in darkness or by a contralateral instillation of 2.5% lidocaine. It is suggested that the failure reflects an overload of the vestibulo-oculomotor circuits. After recovery from the nerve blockade, when the gaze was stable, dynamic vestibular tests were performed. They revealed that a decrease of the slow phase velocity gain and the dominant time constant during, respectively, sinusoidal- and step stimulation toward the unanaesthetised side, had developed with the nerve blockade. These modulations were impaired by a nodulo-uvulectomy but not by bilateral flocculectomy, which is consistent with the concept of vestibular habituation. A GABA(B) receptor antagonist, CGP 56433A, given systemically during the nerve blockade, aggravated the vestibular asymmetry. The same effect has previously been demonstrated in both short- (days) and long-term (months) compensated rats, by antagonising the GABA(B) receptor. In summary, this study provides the first observations of vestibulo-oculomotor disturbances during the first hour after a rapid and transient unilateral vestibular loss in the rat. By using this method, it is possible to study immediate behavioural consequences and possible neural changes that might outlast the nerve blockade.

Substance P contributes to rapidly adapting receptor responses to pulmonary venous congestion in rabbits.

PubMed

Bonham, A C; Kott, K S; Ravi, K; Kappagoda, C T; Joad, J P

1996-05-15

1. This study tested the hypothesis that substance P stimulates rapidly adapting receptors (RARs), contributes to the increase in RAR activity produced by mild pulmonary congestion, and evokes an augmented response from RARs when combined with near-threshold levels of pulmonary congestion. 2. RAR activity, peak tracheal pressure, arterial blood pressure and left atrial pressure were measured in paralysed, anaesthetized and ventilated rabbits. Substance P was given i.v. in one-half log incremental doses to a maximum of 3 micrograms kg-1. Mild pulmonary congestion was produced by inflating a balloon in the left atrium to increase left atrial pressure by 5 mmHg. Near-threshold levels of pulmonary congestion were produced by increasing left atrial pressure by 2 mmHg. 3. Substance P produced dose-dependent increases in RAR activity. The highest dose given increased the activity from 1.3 +/- 0.5 to 11.0 +/- 3.1 impulses bin-1. Increases in left atrial pressure of 5 mmHg increased RAR activity from 3.8 +/- 1.4 to 14.7 +/- 3.9 impulses bin-1. Blockade of NK1 receptors with CP 96345 significantly attenuated RAR responses to substance P and to mild pulmonary congestion. 4. Doses of substance P, which alone had no effect, stimulated the RARs when delivered during near-threshold levels of pulmonary congestion. 5. The findings suggest that substance P augments the stimulatory effect of mild pulmonary congestion on RAR activity, most probably by enhancing hydraulically induced microvascular leak.

The role of sympathetic and vagal cardiac control on complexity of heart rate dynamics.

PubMed

Silva, Luiz Eduardo Virgilio; Silva, Carlos Alberto Aguiar; Salgado, Helio Cesar; Fazan, Rubens

2017-03-01

Analysis of heart rate variability (HRV) by nonlinear approaches has been gaining interest due to their ability to extract additional information from heart rate (HR) dynamics that are not detectable by traditional approaches. Nevertheless, the physiological interpretation of nonlinear approaches remains unclear. Therefore, we propose long-term (60 min) protocols involving selective blockade of cardiac autonomic receptors to investigate the contribution of sympathetic and parasympathetic function upon nonlinear dynamics of HRV. Conscious male Wistar rats had their electrocardiogram (ECG) recorded under three distinct conditions: basal, selective (atenolol or atropine), or combined (atenolol plus atropine) pharmacological blockade of autonomic muscarinic or β 1 -adrenergic receptors. Time series of RR interval were assessed by multiscale entropy (MSE) and detrended fluctuation analysis (DFA). Entropy over short (1 to 5, MSE 1-5 ) and long (6 to 30, MSE 6-30 ) time scales was computed, as well as DFA scaling exponents at short (α short , 5 ≤ n ≤ 15), mid (α mid , 30 ≤ n ≤ 200), and long (α long , 200 ≤ n ≤ 1,700) window sizes. The results show that MSE 1-5 is reduced under atropine blockade and MSE 6-30 is reduced under atropine, atenolol, or combined blockade. In addition, while atropine expressed its maximal effect at scale six, the effect of atenolol on MSE increased with scale. For DFA, α short decreased during atenolol blockade, while the α mid increased under atropine blockade. Double blockade decreased α short and increased α long Results with surrogate data show that the dynamics during combined blockade is not random. In summary, sympathetic and vagal control differently affect entropy (MSE) and fractal properties (DFA) of HRV. These findings are important to guide future studies. NEW & NOTEWORTHY Although multiscale entropy (MSE) and detrended fluctuation analysis (DFA) are recognizably useful prognostic/diagnostic methods, their physiological interpretation remains unclear. The present study clarifies the effect of the cardiac autonomic control on MSE and DFA, assessed during long periods (1 h). These findings are important to help the interpretation of future studies. Copyright © 2017 the American Physiological Society.

Methylxanthine reversal of opioid-evoked inspiratory depression via phosphodiesterase-4 blockade.

PubMed

Ruangkittisakul, Araya; Ballanyi, Klaus

2010-07-31

Hypothetic mechanisms for respirogenic methylxanthine actions include blockade of adenosine receptors or phosphodiesterase-4 (PDE4) in inspiratory pre-Bötzinger complex (preBötC) networks. Here, we studied this by analyzing stimulating caffeine and theophylline actions on mu-opioid-depressed inspiratory-related rhythm in the ventrolateral aspect of rat brainstem slices. The methylxanthines restored DAMGO (0.5-1 microM) depressed rhythm only at >1mM, which is approximately 10-fold higher than selective for adenosine receptors. Adenosine receptor blockers did neither counter DAMGO inhibition nor change control rhythm, similar to adenosine (0.1-2.5 mM). The specific PDE4 blocker rolipram (5 microM) restored DAMGO-depressed rhythm incompletely, but effectively reversed similar inhibition by clinical mu-agonist (fentanyl, 0.1 microM). At 0.25 microM, rolipram boosted incomplete recovery by 1 mM theophylline of DAMGO-depressed rhythm. Findings indicate that methylxanthines excite rhythmogenic preBötC networks via blockade of cAMP dependent PDE4 and suggest that specific PDE4 inhibitors (plus low methylxanthine doses) stimulate breathing effectively. We discuss why methylxanthine doses for preBötC stimulation need to be higher than those for respirogenic effects in vivo. Copyright 2010 Elsevier B.V. All rights reserved.

DIESEL PARTICLE INSTILLATION ENHANCES INFLAMMATORY AND NEUROTROPHIN RESPONSES IN THE LUNGS OF ALLERGIC BALB/C MICE

EPA Science Inventory

Neurotrophins, including nerve growth factor (NGF) partially mediate many features of allergic airways disease including airways resistance and inflammation. Antibody blockade of NGF attenuates airways resistance associated with the allergen-specific airways responses in mice. ...

Adenosine signaling contributes to ethanol-induced fatty liver in mice

PubMed Central

Peng, Zhongsheng; Borea, Pier Andrea; Wilder, Tuere; Yee, Herman; Chiriboga, Luis; Blackburn, Michael R.; Azzena, Gianfranco; Resta, Giuseppe; Cronstein, Bruce N.

2009-01-01

Fatty liver is commonly associated with alcohol ingestion and abuse. While the molecular pathogenesis of these fatty changes is well understood, the biochemical and pharmacological mechanisms by which ethanol stimulates these molecular changes remain unknown. During ethanol metabolism, adenosine is generated by the enzyme ecto-5′-nucleotidase, and adenosine production and adenosine receptor activation are known to play critical roles in the development of hepatic fibrosis. We therefore investigated whether adenosine and its receptors play a role in the development of alcohol-induced fatty liver. WT mice fed ethanol on the Lieber-DeCarli diet developed hepatic steatosis, including increased hepatic triglyceride content, while mice lacking ecto-5′-nucleotidase or adenosine A1 or A2B receptors were protected from developing fatty liver. Similar protection was also seen in WT mice treated with either an adenosine A1 or A2B receptor antagonist. Steatotic livers demonstrated increased expression of genes involved in fatty acid synthesis, which was prevented by blockade of adenosine A1 receptors, and decreased expression of genes involved in fatty acid metabolism, which was prevented by blockade of adenosine A2B receptors. In vitro studies supported roles for adenosine A1 receptors in promoting fatty acid synthesis and for A2B receptors in decreasing fatty acid metabolism. These results indicate that adenosine generated by ethanol metabolism plays an important role in ethanol-induced hepatic steatosis via both A1 and A2B receptors and suggest that targeting adenosine receptors may be effective in the prevention of alcohol-induced fatty liver. PMID:19221436

Peripheral cannabinoid-1 receptor blockade restores hypothalamic leptin signaling.

PubMed

Tam, Joseph; Szanda, Gergő; Drori, Adi; Liu, Ziyi; Cinar, Resat; Kashiwaya, Yoshihiro; Reitman, Marc L; Kunos, George

2017-10-01

In visceral obesity, an overactive endocannabinoid/CB 1 receptor (CB 1 R) system promotes increased caloric intake and decreases energy expenditure, which are mitigated by global or peripheral CB 1 R blockade. In mice with diet-induced obesity (DIO), inhibition of food intake by the peripherally restricted CB 1 R antagonist JD5037 could be attributed to endogenous leptin due to the rapid reversal of hyperleptinemia that maintains leptin resistance, but the signaling pathway engaged by leptin has remained to be determined. We analyzed the hypothalamic circuitry targeted by leptin following chronic treatment of DIO mice with JD5037. Leptin treatment or an increase in endogenous leptin following fasting/refeeding induced STAT3 phosphorylation in neurons in the arcuate nucleus (ARC) in lean and JD5037-treated DIO mice, but not in vehicle-treated DIO animals. Co-localization of pSTAT3 in leptin-treated mice was significantly less common with NPY + than with POMC + ARC neurons. The hypophagic effect of JD5037 was absent in melanocortin-4 receptor (MC4R) deficient obese mice or DIO mice treated with a MC4R antagonist, but was maintained in NPY -/- mice kept on a high-fat diet. Peripheral CB 1 R blockade in DIO restores sensitivity to endogenous leptin, which elicits hypophagia via the re-activation of melanocortin signaling in the ARC. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

Blockade of Nociceptin Signaling Reduces Biochemical, Structural and Cognitive Deficits after Traumatic Brain Injury

DTIC Science & Technology

2010-07-01

also will determine if ORL1 antagonists block downstream gene transcription subsequent to enzyme activation. BODY: Task 1a was to optimize blast...value between 60 and 80 psi at which defects in vestibulomotor function can be detected. These findings could potentially become a clinical...nociceptin-mediated desensitization of opioid receptor-like 1 receptor and mu opioid receptors involves protein kinase C: a molecular mechanism for

Full central neurokinin-1 receptor blockade is required for efficacy in depression: evidence from orvepitant clinical studies.

PubMed

Ratti, Emiliangelo; Bettica, Paolo; Alexander, Robert; Archer, Graeme; Carpenter, David; Evoniuk, Gary; Gomeni, Roberto; Lawson, Erica; Lopez, Monica; Millns, Helen; Rabiner, Eugenii A; Trist, David; Trower, Michael; Zamuner, Stefano; Krishnan, Ranga; Fava, Maurizio

2013-05-01

Full, persistent blockade of central neurokinin-1 (NK1) receptors may be a potential antidepressant mechanism. The selective NK1 antagonist orvepitant (GW823296) was used to test this hypothesis. A preliminary positron emission tomography study in eight male volunteers drove dose selection for two randomized six week studies in patients with major depressive disorder (MDD). Displacement of central [(11)C]GR205171 binding indicated that oral orvepitant doses of 30-60 mg/day provided >99% receptor occupancy for ≥24 h. Studies 733 and 833 randomized patients with MDD and 17-item Hamilton Depression Rating Scale (HAM-D)≥22 to double-blind treatment with orvepitant 30 mg/day, orvepitant 60 mg/day or placebo (1:1:1). Primary outcome measure was change from baseline in 17-item HAM-D total score at Week 6 analyzed using mixed models repeated measures. Study 733 (n=328) demonstrated efficacy on the primary endpoint (estimated drug-placebo differences of 30 mg: -2.41, 95% confidence interval (CI) (-4.50 to -0.31) p=0.0245; 60 mg: -2.86, 95% CI (-4.97 to -0.75) p=0.0082). Study 833 (n=345) did not show significance (estimated drug-placebo differences of 30 mg: -1.67, 95% CI (-3.73 to 0.39) p=0.1122; 60 mg: -0.76, 95% CI (-2.85 to 1.32) p=0.4713). The results support the hypothesis that full, long lasting blockade of central NK1 receptors may be an efficacious mechanism for the treatment of MDD.

The Effect of Opioid Receptor Blockade on the Neural Processing of Thermal Stimuli

PubMed Central

Schoell, Eszter D.; Bingel, Ulrike; Eippert, Falk; Yacubian, Juliana; Christiansen, Kerrin; Andresen, Hilke; May, Arne; Buechel, Christian

2010-01-01

The endogenous opioid system represents one of the principal systems in the modulation of pain. This has been demonstrated in studies of placebo analgesia and stress-induced analgesia, where anti-nociceptive activity triggered by pain itself or by cognitive states is blocked by opioid antagonists. The aim of this study was to characterize the effect of opioid receptor blockade on the physiological processing of painful thermal stimulation in the absence of cognitive manipulation. We therefore measured BOLD (blood oxygen level dependent) signal responses and intensity ratings to non-painful and painful thermal stimuli in a double-blind, cross-over design using the opioid receptor antagonist naloxone. On the behavioral level, we observed an increase in intensity ratings under naloxone due mainly to a difference in the non-painful stimuli. On the neural level, painful thermal stimulation was associated with a negative BOLD signal within the pregenual anterior cingulate cortex, and this deactivation was abolished by naloxone. PMID:20811582

Complement Receptor 1 Is a Sialic Acid-Independent Erythrocyte Receptor of Plasmodium falciparum

DTIC Science & Technology

2010-06-17

Pennsylvania State University College of Medicine, Hershey , Pennsylvania, United States of America Abstract Plasmodium falciparum is a highly lethal malaria...www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.1000968 Zimmerli S, Edwards S, Ernst JD ( 1996 ) Selective receptor blockade...in field isolates. J Immunol 165: 6341–6346. 22. Baruch DI, Gormely JA, Ma C, Howard RJ, Pasloske BL ( 1996 ) Plasmodium falciparum erythrocyte

Perirhinal Cortex Muscarinic Receptor Blockade Impairs Taste Recognition Memory Formation

ERIC Educational Resources Information Center

Gutierrez, Ranier; De la Cruz, Vanesa; Rodriguez-Ortiz, Carlos J.; Bermudez-Rattoni, Federico

2004-01-01

The relevance of perirhinal cortical cholinergic and glutamatergic neurotransmission for taste recognition memory and learned taste aversion was assessed by microinfusions of muscarinic (scopolamine), NMDA (AP-5), and AMPA (NBQX) receptor antagonists. Infusions of scopolamine, but not AP5 or NBQX, prevented the consolidation of taste recognition…

Isoproterenol reduces ischemia-reperfusion lung injury despite beta-blockade.

PubMed

Takashima, Seiki; Schlidt, Scott A; Koukoulis, Giovanna; Sevala, Mayura; Egan, Thomas M

2005-06-01

If lungs could be retrieved from non-heart-beating donors (NHBDs), the shortage of lungs for transplantation could be alleviated. The use of lungs from NHBDs is associated with a mandatory warm ischemic interval, which results in ischemia-reperfusion injury upon reperfusion. In an earlier study, rat lungs retrieved 2-h postmortem from NHBDs had reduced capillary leak measured by filtration coefficient (Kfc) when reperfused with isoproterenol (iso), associated with an increase in lung tissue levels of cyclic AMP (cAMP). The objective was to determine if this decrease in Kfc was because of beta-stimulation, or would persist despite beta-blockade. Donor rats were treated intraperitoneally with beta-blockade (propranolol or pindolol) or carrier, sacrificed, and lungs were retrieved immediately or 2 h postmortem. The lungs were reperfused with or without iso and the beta-blockers in the reperfusate. Outcome measures were Kfc, wet:dry weight ratio (W/D), lung levels of adenine nucleotides and cAMP. Lungs retrieved immediately after death had normal Kfc and W/D. After 2 h of ischemia, Kfc and W/D were markedly elevated in controls (no drug) and lungs reperfused with beta-blockers alone. Isoproterenol-reperfusion decreased Kfc and W/D significantly (P < 0.01) even in the presence of beta-blockade. Lung cAMP levels were increased only with iso in the absence of beta-blockade. The attenuation of ischemia-reperfusion injury because of iso occurs even in the presence of beta-blockade, and may not be a result of beta-stimulated increased cAMP.

Chronic infusion of enalaprilat into hypothalamic paraventricular nucleus attenuates angiotensin II-induced hypertension and cardiac hypertrophy by restoring neurotransmitters and cytokines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kang, Yu-Ming, E-mail: ykang@mail.xjtu.edu.cn; Zhang, Dong-Mei; Yu, Xiao-Jing

The renin–angiotensin system (RAS) in the brain is involved in the pathogenesis of hypertension. We hypothesized that inhibition of angiotensin-converting enzyme (ACE) in the hypothalamic paraventricular nucleus (PVN) attenuates angiotensin II (ANG II)-induced hypertension via restoring neurotransmitters and cytokines. Rats underwent subcutaneous infusions of ANG II or saline and bilateral PVN infusions of ACE inhibitor enalaprilat (ENL, 2.5 μg/h) or vehicle for 4 weeks. ANG II infusion resulted in higher mean arterial pressure and cardiac hypertrophy as indicated by increased whole heart weight/body weight ratio, whole heart weight/tibia length ratio, left ventricular weight/tibia length ratio, and mRNA expressions of cardiacmore » atrial natriuretic peptide and beta-myosin heavy chain. These ANG II-infused rats had higher PVN levels of glutamate, norepinephrine, tyrosine hydroxylase, pro-inflammatory cytokines (PICs) and the chemokine monocyte chemoattractant protein-1, and lower PVN levels of gamma-aminobutyric acid, interleukin (IL)-10 and the 67-kDa isoform of glutamate decarboxylase (GAD67), and higher plasma levels of PICs, norepinephrine and aldosterone, and lower plasma IL-10, and higher renal sympathetic nerve activity. However, PVN treatment with ENL attenuated these changes. PVN microinjection of ANG II induced increases in IL-1β and IL-6, and a decrease in IL-10 in the PVN, and pretreatment with angiotensin II type 1 receptor (AT1-R) antagonist losartan attenuated these changes. These findings suggest that ANG II infusion induces an imbalance between excitatory and inhibitory neurotransmitters and an imbalance between pro- and anti-inflammatory cytokines in the PVN, and PVN inhibition of the RAS restores neurotransmitters and cytokines in the PVN, thereby attenuating ANG II-induced hypertension and cardiac hypertrophy. - Highlights: • Chronic ANG II infusion results in sympathetic hyperactivity and cardiac hypertrophy. • PVN inhibition of ACE attenuates ANG II-induced hypertension and cardiac hypertrophy. • PVN inhibition of ACE attenuates ANG II-induced imbalance of PVN neurotransmitters. • PVN inhibition of ACE attenuates ANG II-induced imbalance of cytokines in the PVN. • PVN blockade of AT1-R attenuates ANG II-induced imbalance of cytokines in the PVN.« less

PI3 kinase inhibition improves vascular malformations in mouse models of hereditary haemorrhagic telangiectasia.

PubMed

Ola, Roxana; Dubrac, Alexandre; Han, Jinah; Zhang, Feng; Fang, Jennifer S; Larrivée, Bruno; Lee, Monica; Urarte, Ana A; Kraehling, Jan R; Genet, Gael; Hirschi, Karen K; Sessa, William C; Canals, Francesc V; Graupera, Mariona; Yan, Minhong; Young, Lawrence H; Oh, Paul S; Eichmann, Anne

2016-11-29

Activin receptor-like kinase 1 (ALK1) is an endothelial serine-threonine kinase receptor for bone morphogenetic proteins (BMPs) 9 and 10. Inactivating mutations in the ALK1 gene cause hereditary haemorrhagic telangiectasia type 2 (HHT2), a disabling disease characterized by excessive angiogenesis with arteriovenous malformations (AVMs). Here we show that inducible, endothelial-specific homozygous Alk1 inactivation and BMP9/10 ligand blockade both lead to AVM formation in postnatal retinal vessels and internal organs including the gastrointestinal (GI) tract in mice. VEGF and PI3K/AKT signalling are increased on Alk1 deletion and BMP9/10 ligand blockade. Genetic deletion of the signal-transducing Vegfr2 receptor prevents excessive angiogenesis but does not fully revert AVM formation. In contrast, pharmacological PI3K inhibition efficiently prevents AVM formation and reverts established AVMs. Thus, Alk1 deletion leads to increased endothelial PI3K pathway activation that may be a novel target for the treatment of vascular lesions in HHT2.

Aldosterone and angiotensin II synergistically induce mitogenic response in vascular smooth muscle cells.

PubMed

Min, Li-Juan; Mogi, Masaki; Li, Jian-Mei; Iwanami, Jun; Iwai, Masaru; Horiuchi, Masatsugu

2005-09-02

Interaction between aldosterone (Aldo) and angiotensin II (Ang II) in the cardiovascular system has been highlighted; however, its detailed signaling mechanism is poorly understood. Here, we examined the cross-talk of growth-promoting signaling between Aldo and Ang II in vascular smooth muscle cells (VSMC). Treatment with a lower dose of Aldo (10(-12) mol/L) and with a lower dose of Ang II (10(-10) mol/L) significantly enhanced DNA synthesis, whereas Aldo or Ang II alone at these doses did not affect VSMC proliferation. This effect of a combination of Aldo and Ang II was markedly inhibited by a selective AT1 receptor blocker, olmesartan, a mineralocorticoid receptor antagonist, spironolactone, an MEK inhibitor, PD98059, or an EGF receptor tyrosine kinase inhibitor, AG1478. Treatment with Aldo together with Ang II, even at noneffective doses, respectively, synergistically increased extracellular signal-regulated kinase (ERK) activation, reaching 2 peaks at 10 to 15 minutes and 2 to 4 hours. The early ERK peak was effectively blocked by olmesartan or an EGF receptor kinase inhibitor, AG1478, but not by spironolactone, whereas the late ERK peak was completely inhibited by not only olmesartan, but also spironolactone. Combined treatment with Aldo and Ang II attenuated mitogen-activated protein kinase phosphatase-1 (MKP-1) expression and increased Ki-ras2A expression. The late ERK peak was not observed in VSMC treated with Ki-ras2A-siRNA. Interestingly, the decrease in MKP-1 expression and the increase in Ki-ras2A expression were restored by PD98059 or AG1478. These results suggest that Aldo exerts a synergistic mitogenic effect with Ang II and support the notion that blockade of both Aldo and Ang II could be more effective to prevent vascular remodeling.

Immunotherapeutic implications of IL-6 blockade for cytokine storm.

PubMed

Tanaka, Toshio; Narazaki, Masashi; Kishimoto, Tadamitsu

2016-07-01

IL-6 contributes to host defense against infections and tissue injuries. However, exaggerated, excessive synthesis of IL-6 while fighting environmental stress leads to an acute severe systemic inflammatory response known as 'cytokine storm', since high levels of IL-6 can activate the coagulation pathway and vascular endothelial cells but inhibit myocardial function. Remarkable beneficial effects of IL-6 blockade therapy using a humanized anti-IL-6 receptor antibody, tocilizumab were recently observed in patients with cytokine release syndrome complicated by T-cell engaged therapy. In this review we propose the possibility that IL-6 blockade may constitute a novel therapeutic strategy for other types of cytokine storm, such as the systemic inflammatory response syndrome including sepsis, macrophage activation syndrome and hemophagocytic lymphohistiocytosis.

5-HT1A receptor blockade reverses GABAA receptor α3 subunit-mediated anxiolytic effects on stress-induced hyperthermia

PubMed Central

van Oorschot, Ruud; Korte, S. Mechiel; Olivier, Berend; Groenink, Lucianne

2010-01-01

Rationale Stress-related disorders are associated with dysfunction of both serotonergic and GABAergic pathways, and clinically effective anxiolytics act via both neurotransmitter systems. As there is evidence that the GABAA and the serotonin receptor system interact, a serotonergic component in the anxiolytic actions of benzodiazepines could be present. Objectives The main aim of the present study was to investigate whether the anxiolytic effects of (non-)selective α subunit GABAA receptor agonists could be reversed with 5-HT1A receptor blockade using the stress-induced hyperthermia (SIH) paradigm. Results The 5-HT1A receptor antagonist WAY-100635 (0.1–1 mg/kg) reversed the SIH-reducing effects of the non-α-subunit selective GABAA receptor agonist diazepam (1–4 mg/kg) and the GABAA receptor α3-subunit selective agonist TP003 (1 mg/kg), whereas WAY-100635 alone was without effect on the SIH response or basal body temperature. At the same time, co-administration of WAY-100635 with diazepam or TP003 reduced basal body temperature. WAY-100635 did not affect the SIH response when combined with the preferential α1-subunit GABAA receptor agonist zolpidem (10 mg/kg), although zolpidem markedly reduced basal body temperature. Conclusions The present study suggests an interaction between GABAA receptor α-subunits and 5-HT1A receptor activation in the SIH response. Specifically, our data indicate that benzodiazepines affect serotonergic signaling via GABAA receptor α3-subunits. Further understanding of the interactions between the GABAA and serotonin system in reaction to stress may be valuable in the search for novel anxiolytic drugs. PMID:20535452

Purple sweet potato color attenuates domoic acid-induced cognitive deficits by promoting estrogen receptor-α-mediated mitochondrial biogenesis signaling in mice.

PubMed

Lu, Jun; Wu, Dong-Mei; Zheng, Yuan-Lin; Hu, Bin; Cheng, Wei; Zhang, Zi-Feng

2012-02-01

Recent findings suggest that endoplasmic reticulum stress may be involved in the pathogenesis of domoic acid-induced neurodegeneration. Purple sweet potato color, a class of naturally occurring anthocyanins, has beneficial health and biological effects. Recent studies have also shown that anthocyanins have estrogenic activity and can enhance estrogen receptor-α expression. In this study, we evaluated the effect of purple sweet potato color on cognitive deficits induced by hippocampal mitochondrial dysfunction in domoic acid-treated mice and explored the potential mechanisms underlying this effect. Our results showed that the oral administration of purple sweet potato color to domoic acid-treated mice significantly improved their behavioral performance in a step-through passive avoidance task and a Morris water maze task. These improvements were mediated, at least in part, by a stimulation of estrogen receptor-α-mediated mitochondrial biogenesis signaling and by decreases in the expression of p47phox and gp91phox. Decreases in reactive oxygen species and protein carbonylation were also observed, along with a blockade of the endoplasmic reticulum stress pathway. Furthermore, purple sweet potato color significantly suppressed endoplasmic reticulum stress-induced apoptosis, which prevented neuron loss and restored the expression of memory-related proteins. However, knockdown of estrogen receptor-α using short hairpin RNA only partially blocked the neuroprotective effects of purple sweet potato color in the hippocampus of mice cotreated with purple sweet potato color and domoic acid, indicating that purple sweet potato color acts through multiple pathways. These results suggest that purple sweet potato color could be a possible candidate for the prevention and treatment of cognitive deficits in excitotoxic and other brain disorders. Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.

Enduring abolishment of remote but not recent expression of conditioned fear by the blockade of calcium-permeable AMPA receptors before extinction training.

PubMed

Zelena, Dóra; Mikics, Éva; Balázsfi, Diána; Varga, János; Klausz, Barbara; Urbán, Eszter; Sipos, Eszter; Biró, László; Miskolczi, Christina; Kovács, Krisztina; Ferenczi, Szilamér; Haller, József

2016-06-01

Calcium-permeable (GluA2 subunit-free) AMPA receptors (CP-AMPAR) play prominent roles in fear extinction; however, no blockers of these receptors were studied in tests relevant to extinction learning so far. The CP-AMPAR antagonist IEM-1460 was administered once before extinction trainings, which were started either 1 or 28 days after fear conditioning (FC). We used a mild extinction protocol that durably decreased but did not abolish conditioned fear. The messenger RNA (mRNA) expression of GluA1 and GluA2 subunits were investigated at both time points in the ventromedial prefrontal cortex (vmPFC) and amygdala. IEM-1460 transiently facilitated extinction 1 day after conditioning, but learned fear spontaneously recovered 4 weeks later. When the extinction protocol was applied 28 days after training, IEM-1460 enhanced extinction memory, moreover abolished conditioned fear for at least a month. The expression of GluA1 and GluA2 mRNAs was increased at both time points in the vmPFC. In the basolateral and central amygdala, the GluA1/GluA2 mRNA ratio increased, suggesting a shift towards the preponderance of GluA1 over GluA2 expression. AMPAR blockade lastingly enhanced the extinction of remote but not recent fear memories. Time-dependent changes in AMPA receptor subunit mRNA expression may explain the differential effects of CP-AMPAR blockade on recent and remote conditioned fear, further supporting the notion that the mechanisms maintaining learned fear change over time. Our findings suggest clinical implications for CP-AMPAR blockers, particularly for acquired anxieties (e.g., post-traumatic stress disorder) which have a slow onset and are durable.

THE REELIN RECEPTORS VLDLR AND ApoER2 REGULATE SENSORIMOTOR GATING IN MICE

PubMed Central

Barr, Alasdair M.; Fish, Kenneth N.; Markou, Athina

2007-01-01

Summary Postmortem brain loss of reelin is noted in schizophrenia patients. Accordingly, heterozygous reeler mutant mice have been proposed as a putative model of this disorder. Little is known, however, about the involvement of the two receptors for reelin, Very-Low-Density Lipoprotein Receptor (VLDLR) and Apolipoprotein E Receptor 2 (ApoER2), on pre-cognitive processes of relevance to deficits seen in schizophrenia. Thus, we evaluated sensorimotor gating in mutant mice heterozygous or homozygous for the two reelin receptors. Mutant mice lacking one of these reelin receptors were tested for prepulse inhibition (PPI) of the acoustic startle reflex prior to and following puberty, and on a crossmodal PPI task, involving the presentation of acoustic and tactile stimuli. Furthermore, because schizophrenia patients show increased sensitivity to N-methyl-D-aspartate (NMDA) receptor blockade, we assessed the sensitivity of these mice to the PPI-disruptive effects of the NMDA receptor antagonist phencyclidine. The results demonstrated that acoustic PPI did not differ between mutant and wildtype mice. However, VLDLR homozygous mice displayed significant deficits in crossmodal PPI, while ApoER2 heterozygous and homozygous mice displayed significantly increased crossmodal PPI. Both ApoER2 and VLDLR heterozygous and homozygous mice exhibited greater sensitivity to the PPI-disruptive effects of phencyclidine than wildtype mice. These results indicate that partial or complete loss of either one of the reelin receptors results in a complex pattern of alterations in PPI function that include alterations in crossmodal, but not acoustic, PPI and increased sensitivity to NMDA receptor blockade. Thus, reelin receptor function appears to be critically involved in crossmodal PPI and the modulation of the PPI response by NMDA receptors. These findings have relevance to a range of neuropsychiatric disorders that involve sensorimotor gating deficits, including schizophrenia.. PMID:17261317

Cannabidiol Modulates Fear Memory Formation Through Interactions with Serotonergic Transmission in the Mesolimbic System

PubMed Central

Norris, Christopher; Loureiro, Michael; Kramar, Cecilia; Zunder, Jordan; Renard, Justine; Rushlow, Walter; Laviolette, Steven R

2016-01-01

Emerging evidence suggests that the largest phytochemical component of cannabis, cannabidiol (CBD), may possess pharmacotherapeutic properties in the treatment of neuropsychiatric disorders. CBD has been reported to functionally interact with both the mesolimbic dopamine (DA) and serotonergic (5-HT) receptor systems. However, the underlying mechanisms by which CBD may modulate emotional processing are not currently understood. Using a combination of in vivo electrophysiological recording and fear conditioning in rats, the present study aimed to characterize the behavioral, neuroanatomical, and pharmacological effects of CBD within the mesolimbic pathway, and its possible functional interactions with 5-HT and DAergic transmission. Using targeted microinfusions of CBD into the shell region of the mesolimbic nucleus accumbens (NASh), we report that intra-NASh CBD potently blocks the formation of conditioned freezing behaviors. These effects were challenged with DAergic, cannabinoid CB1 receptor, and serotonergic (5-HT1A) transmission blockade, but only 5-HT1A blockade restored associative conditioned freezing behaviors. In vivo intra-ventral tegmental area (VTA) electrophysiological recordings revealed that behaviorally effective doses of intra-NASh CBD elicited a predominant decrease in spontaneous DAergic neuronal frequency and bursting activity. These neuronal effects were reversed by simultaneous blockade of 5-HT1A receptor transmission. Finally, using a functional contralateral disconnection procedure, we demonstrated that the ability of intra-NASh CBD to block the formation of conditioned freezing behaviors was dependent on intra-VTA GABAergic transmission substrates. Our findings demonstrate a novel NAc→VTA circuit responsible for the behavioral and neuronal effects of CBD within the mesolimbic system via functional interactions with serotonergic 5-HT1A receptor signaling. PMID:27296152

Sarcosine attenuates toluene-induced motor incoordination, memory impairment, and hypothermia but not brain stimulation reward enhancement in mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, Ming-Huan; Institute of Neuroscience, National Changchi University, Taipei, Taiwan; Chung, Shiang-Sheng

Toluene, a widely used and commonly abused organic solvent, produces various behavioral disturbances, including motor incoordination and cognitive impairment. Toluene alters the function of a large number of receptors and ion channels. Blockade of N-methyl-D-aspartate (NMDA) receptors has been suggested to play a critical role in toluene-induced behavioral manifestations. The present study determined the effects of various toluene doses on motor coordination, recognition memory, body temperature, and intracranial self-stimulation (ICSS) thresholds in mice. Additionally, the effects of sarcosine on the behavioral and physiological effects induced by toluene were evaluated. Sarcosine may reverse toluene-induced behavioral manifestations by acting as an NMDAmore » receptor co-agonist and by inhibiting the effects of the type I glycine transporter (GlyT1). Mice were treated with toluene alone or combined with sarcosine pretreatment and assessed for rotarod performance, object recognition memory, rectal temperature, and ICSS thresholds. Toluene dose-dependently induced motor incoordination, recognition memory impairment, and hypothermia and lowered ICSS thresholds. Sarcosine pretreatment reversed toluene-induced changes in rotarod performance, novel object recognition, and rectal temperature but not ICSS thresholds. These findings suggest that the sarcosine-induced potentiation of NMDA receptors may reverse motor incoordination, memory impairment, and hypothermia but not the enhancement of brain stimulation reward function associated with toluene exposure. Sarcosine may be a promising compound to prevent acute toluene intoxications by occupational or intentional exposure. -- Highlights: ► Toluene induces impairments in Rotarod test and novel object recognition test. ► Toluene lowers rectal temperature and ICSS thresholds in mice. ► Sarcosine reverses toluene-induced changes in motor, memory and body temperature. ► Sarcosine pretreatment does not affect toluene-induced reward enhancement.« less

Minimally Invasive Surgery (MIS) in Children and Adolescents with Pheochromocytomas and Retroperitoneal Paragangliomas: Experiences in 42 Patients.

PubMed

Walz, Martin K; Iova, Laura D; Deimel, Judith; Neumann, Hartmut P H; Bausch, Birke; Zschiedrich, Stefan; Groeben, Harald; Alesina, Pier F

2018-04-01

Pheochromocytomas (PH) and paragangliomas (PGL) are rare tumours in children accounting for about 1% of the paediatric hypertension. While minimally invasive surgical techniques are well established in adult patients with PH, the experience in children is extremely limited. To the best of our knowledge, we herewith present the largest series of young patients operated on chromaffin tumours by minimally invasive access. In the setting of a prospective study (1/2001-12/2016), 42 consecutive children and adolescents (33 m, 9 f) were operated on. Thirty-seven patients (88%) suffered from inherited diseases. Twenty-six patients had PH, 11 presented retroperitoneal PGL, and five patients suffered from both. Altogether, 70 tumours (mean size 2.7 cm) were removed (45 PH, 25 PGL). All operations were performed by a minimally invasive access (retroperitoneoscopic, laparoscopic, extraperitoneal). Partial adrenalectomy was the preferred procedure for PH (31 out of 39 patients). Twenty patients received α-receptor blockade preoperatively. One patient died after induction of anaesthesia due to cardiac arrest. All other complications were minor. Conversion to open surgery was necessary in two cases with PGL. Median operating time for unilateral PH was 55 min, in bilateral cases 125, 143 min in PGs, and 180 min in combined cases. Median blood loss was 20 ml (range 0-1000). Blood transfusion was necessary in two cases. Intraoperative, systolic peak pressure was 170 ± 39 mmHg with α-receptor blockade and 191 ± 33 mmHg without α-receptor blockade (p = 0.41). The median post-operative hospital stay was 3 days. After a mean follow-up of 8.5 years, two patients presented ipsilateral recurrence (after partial adrenalectomy). All patients with bilateral PH (n = 13) are steroid independent post-operatively. PH and PGL in children and adolescents should preferably be removed by minimally invasive surgery. Partial adrenalectomy provides long-term steroid independence in bilateral PH and a low rate of (ipsilateral) recurrence. α-Receptor blockade may not be necessary in these patients.

Enhancement of Adipocyte Browning by Angiotensin II Type 1 Receptor Blockade.

PubMed

Tsukuda, Kana; Mogi, Masaki; Iwanami, Jun; Kanno, Harumi; Nakaoka, Hirotomo; Wang, Xiao-Li; Bai, Hui-Yu; Shan, Bao-Shuai; Kukida, Masayoshi; Higaki, Akinori; Yamauchi, Toshifumi; Min, Li-Juan; Horiuchi, Masatsugu

2016-01-01

Browning of white adipose tissue (WAT) has been highlighted as a new possible therapeutic target for obesity, diabetes and lipid metabolic disorders, because WAT browning could increase energy expenditure and reduce adiposity. The new clusters of adipocytes that emerge with WAT browning have been named 'beige' or 'brite' adipocytes. Recent reports have indicated that the renin-angiotensin system (RAS) plays a role in various aspects of adipose tissue physiology and dysfunction. The biological effects of angiotensin II, a major component of RAS, are mediated by two receptor subtypes, angiotensin II type 1 receptor (AT1R) and type 2 receptor (AT2R). However, the functional roles of angiotensin II receptor subtypes in WAT browning have not been defined. Therefore, we examined whether deletion of angiotensin II receptor subtypes (AT1aR and AT2R) may affect white-to-beige fat conversion in vivo. AT1a receptor knockout (AT1aKO) mice exhibited increased appearance of multilocular lipid droplets and upregulation of thermogenic gene expression in inguinal white adipose tissue (iWAT) compared to wild-type (WT) mice. AT2 receptor-deleted mice did not show miniaturization of lipid droplets or alteration of thermogenic gene expression levels in iWAT. An in vitro experiment using adipose tissue-derived stem cells showed that deletion of the AT1a receptor resulted in suppression of adipocyte differentiation, with reduction in expression of thermogenic genes. These results indicate that deletion of the AT1a receptor might have some effects on the process of browning of WAT and that blockade of the AT1 receptor could be a therapeutic target for the treatment of metabolic disorders.

Evidence for involvement of nitric oxide and GABAB receptors in MK-801- stimulated release of glutamate in rat prefrontal cortex

PubMed Central

Roenker, Nicole L.; Gudelsky, Gary A.; Ahlbrand, Rebecca; Horn, Paul S.; Richtand, Neil M.

2012-01-01

Systemic administration of NMDA receptor antagonists elevates extracellular glutamate within prefrontal cortex. The cognitive and behavioral effects of NMDA receptor blockade have direct relevance to symptoms of schizophrenia, and recent studies demonstrate an important role for nitric oxide and GABAB receptors in mediating the effects of NMDA receptor blockade on these behaviors. We sought to extend those observations by directly measuring the effects of nitric oxide and GABAB receptor mechanisms on MK-801-induced glutamate release in the prefrontal cortex. Systemic MK-801 injection (0.3 mg/kg) to male Sprague-Dawley rats significantly increased extracellular glutamate levels in prefrontal cortex, as determined by microdialysis. This effect was blocked by pretreatment with the nitric oxide synthase inhibitor L-NAME (60 mg/kg). Reverse dialysis of the nitric oxide donor SNAP (0.5 – 5 mM) directly into prefrontal cortex mimicked the effect of systemic MK-801, dose-dependently elevating cortical extracellular glutamate. The effect of MK-801 was also blocked by systemic treatment with the GABAB receptor agonist baclofen (5 mg/kg). In combination, these data suggest increased nitric oxide formation is necessary for NMDA antagonist-induced elevations of extracellular glutamate in the prefrontal cortex. Additionally, the data suggest GABAB receptor activation can modulate the NMDA antagonist-induced increase in cortical glutamate release. PMID:22579658

Diuretic effects of KW-3902 (8-(noradamantan-3-yl)-1,3-dipropylxanthine), a novel adenosine A1 receptor antagonist, in conscious dogs.

PubMed

Kobayashi, T; Mizumoto, H; Karasawa, A

1993-12-01

The diuretic effects of KW-3902 (8-(noradamantan-3-yl)-1,3-dipropylxanthine), a novel adenosine A1 receptor antagonist, were determined and compared with those of trichlormethiazide (TCM) and furosemide in saline-loaded conscious dogs. KW-3902, at doses higher than 0.1 mg/kg (p.o.), produced dose-dependent increases of urine volume and sodium excretion and these effects were statistically significant at doses of 1-100 mg/kg. The increase in potassium excretion was lower than that of sodium, and the ratio of sodium to potassium excretion (Na/K) tended to be elevated. TCM (0.3 mg/kg) and furosemide (3 mg/kg) also induced increases in urine volume and sodium excretion. The diuretic effects of KW-3902 lasted for 4 h after administration, whereas TCM and furosemide caused significant natriuresis for 2 h after administration. Thus, KW-3902 exhibited a longer lasting natriuresis than TCM and furosemide. These results indicate that adenosine A1 receptor blockade by KW-3902 causes consistent diuresis and natriuresis in dogs and suggest that adenosine A1 receptor blockade is a promising approach to diuretic therapy.

Ionotropic glutamate receptor antagonists and cancer therapy: time to think out of the box?

PubMed

Ribeiro, Mariana P C; Custódio, José B A; Santos, Armanda E

2017-02-01

Glutamate has a trophic function in the development of the central nervous system, regulating the proliferation and migration of neuronal progenitors. The resemblance between neuronal embryonic and tumor cells has paved the way for the investigation of the effects of glutamate on tumor cells. Indeed, tumor cells derived from neuronal tissue express ionotropic glutamate receptor (iGluRs) subunits and iGluR antagonists decrease cell proliferation. Likewise, iGluRs subunits are expressed in several peripheral cancer cells and blockade of the N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) ionotropic glutamate receptor subtypes decreases their proliferation and migration. Although these mechanisms are still being investigated, the inhibition of the mitogen-activated protein kinase pathway was shown to play a key role in the antiproliferative activity of iGluR antagonists. Importantly, MK-801, a NMDAR channel blocker, was effective and well tolerated in animal models of melanoma, lung, and breast cancers, suggesting that the blockade of iGluR signaling may represent a new strategy for cancer treatment. In this review, we focus on the significance of NMDA and AMPA receptor expression in tumor cells, as well as possible therapeutic strategies targeting these receptors.

Influence of age, body temperature, GABAA receptor inhibition and caffeine on the Hering-Breuer inflation reflex in unanesthetized rat pups

PubMed Central

Arnal, Ashley V.; Gore, Julie L.; Rudkin, Alison; Bartlett, Donald; Leiter, J.C.

2013-01-01

We measured the duration of apnea induced by sustained end-inspiratory lung inflation (the Hering Breuer Reflex; HBR) in unanesthetized infant rat pups aged 4 days (P4) to P20 at body temperatures of 32°C and 36°C. The expiratory prolongation elicited by the HBR lasted longer in the younger pups and lasted longer at the higher body temperature. Blockade of adenosine receptors by caffeine following injection into the cisterna magna (ICM) significantly blunted the thermal prolongation of the HBR. Blockade of gama-amino-butyric acid A (GABAA) receptors by pre-treatment with ICM bicuculline had no effect on the HBR duration at either body temperature. To test the hypothesis that developmental maturation of GABAergic inhibition of breathing was modifying the response to bicuculline, we pretreated rat pups with systemically administered bumetanide to lower the intracellular chloride concentration, and repeated the bicuculline studies. Bicuculline still did not alter the HBR at either temperature after bumetanide treatment. We administered PSB-36, a selective adenosine A1 receptor antagonist, and this drug treatment did not modify the HBR. We conclude that caffeine blunts the thermal prolongation of the HBR, probably by blocking adenosine A2a receptors. The thermally-sensitive adenosinergic prolongation of the HBR in these intact animals does not seem to depend on GABAA receptors PMID:23318703

VIP/PACAP receptor mediation of cutaneous active vasodilation during heat stress in humans

PubMed Central

Zhao, Joan L.; Wu, Yubo; Johnson, John M.

2010-01-01

Vasoactive intestinal peptide (VIP) is implicated in cutaneous active vasodilation in humans. VIP and the closely related pituitary adenylate cyclase activating peptide (PACAP) act through several receptor types: VIP through VPAC1 and VPAC2 receptors and PACAP through VPAC1, VPAC2, and PAC1 receptors. We examined participation of VPAC2 and/or PAC1 receptors in cutaneous vasodilation during heat stress by testing the effects of their specific blockade with PACAP6–38. PACAP6–38 dissolved in Ringer's was administered by intradermal microdialysis at one forearm site while a control site received Ringer's solution. Skin blood flow was monitored by laser-Doppler flowmetry (LDF). Blood pressure was monitored noninvasively and cutaneous vascular conductance (CVC) calculated. A 5- to 10-min baseline period was followed by ∼70 min of PACAP6–38 (100 μM) perfusion at one site in normothermia and a 3-min period of body cooling. Whole body heating was then performed to engage cutaneous active vasodilation and was maintained until CVC had plateaued at an elevated level at all sites for 5–10 min. Finally, 58 mM sodium nitroprusside was perfused through both microdialysis sites to effect maximal vasodilation. No CVC differences were found between control and PACAP6–38-treated sites during normothermia (19 ± 3%max untreated vs. 20 ± 3%max, PACAP6–38 treated; P > 0.05 between sites) or cold stress (11 ± 2%max untreated vs. 10 ± 2%max, PACAP6–38 treated, P > 0.05 between sites). PACAP6–38 attenuated the increase in CVC during whole body heating when compared with untreated sites (59 ± 3%max untreated vs. 46 ± 3%max, PACAP6–38 treated, P < 0.05). We conclude that VPAC2 and/or PAC1 receptor activation is involved in cutaneous active vasodilation in humans. PMID:20395540

VIP/PACAP receptor mediation of cutaneous active vasodilation during heat stress in humans.

PubMed

Kellogg, Dean L; Zhao, Joan L; Wu, Yubo; Johnson, John M

2010-07-01

Vasoactive intestinal peptide (VIP) is implicated in cutaneous active vasodilation in humans. VIP and the closely related pituitary adenylate cyclase activating peptide (PACAP) act through several receptor types: VIP through VPAC1 and VPAC2 receptors and PACAP through VPAC1, VPAC2, and PAC1 receptors. We examined participation of VPAC2 and/or PAC1 receptors in cutaneous vasodilation during heat stress by testing the effects of their specific blockade with PACAP6-38. PACAP6-38 dissolved in Ringer's was administered by intradermal microdialysis at one forearm site while a control site received Ringer's solution. Skin blood flow was monitored by laser-Doppler flowmetry (LDF). Blood pressure was monitored noninvasively and cutaneous vascular conductance (CVC) calculated. A 5- to 10-min baseline period was followed by approximately 70 min of PACAP6-38 (100 microM) perfusion at one site in normothermia and a 3-min period of body cooling. Whole body heating was then performed to engage cutaneous active vasodilation and was maintained until CVC had plateaued at an elevated level at all sites for 5-10 min. Finally, 58 mM sodium nitroprusside was perfused through both microdialysis sites to effect maximal vasodilation. No CVC differences were found between control and PACAP6-38-treated sites during normothermia (19 +/- 3%max untreated vs. 20 +/- 3%max, PACAP6-38 treated; P > 0.05 between sites) or cold stress (11 +/- 2%max untreated vs. 10 +/- 2%max, PACAP6-38 treated, P > 0.05 between sites). PACAP6-38 attenuated the increase in CVC during whole body heating when compared with untreated sites (59 +/- 3%max untreated vs. 46 +/- 3%max, PACAP6-38 treated, P < 0.05). We conclude that VPAC2 and/or PAC1 receptor activation is involved in cutaneous active vasodilation in humans.

Ghrelin interacts with neuropeptide Y Y1 and opioid receptors to increase food reward.

PubMed

Skibicka, Karolina P; Shirazi, Rozita H; Hansson, Caroline; Dickson, Suzanne L

2012-03-01

Ghrelin, a stomach-derived hormone, is an orexigenic peptide that was recently shown to potently increase food reward behavior. The neurochemical circuitry that links ghrelin to the mesolimbic system and food reward behavior remains unclear. Here we examined the contribution of neuropeptide Y (NPY) and opioids to ghrelin's effects on food motivation and intake. Both systems have well-established links to the mesolimbic ventral tegmental area (VTA) and reward/motivation control. NPY mediates the effect of ghrelin on food intake via activation of NPY-Y1 receptor (NPY-Y1R); their connection with respect to motivated behavior is unexplored. The role of opioids in any aspect of ghrelin's action on food-oriented behaviors is unknown. Rats were trained in a progressive ratio sucrose-induced operant schedule to measure food reward/motivation behavior. Chow intake was measured immediately after the operant test. In separate experiments, we explored the suppressive effects of a selective NPY-Y1R antagonist or opioid receptor antagonist naltrexone, injected either intracerebroventricularly or intra-VTA, on ghrelin-induced food reward behavior. The ventricular ghrelin-induced increase in sucrose-motivated behavior and chow intake were completely blocked by intracerebroventricular pretreatment with either an NPY-Y1R antagonist or naltrexone. The intra-VTA ghrelin-induced sucrose-motivated behavior was blocked only by intra-VTA naltrexone. In contrast, the intra-VTA ghrelin-stimulated chow intake was attenuated only by intra-VTA NPY-Y1 blockade. Finally, ghrelin infusion was associated with an elevated VTA μ-opioid receptor expression. Thus, we identify central NPY and opioid signaling as the necessary mediators of food intake and reward effects of ghrelin and localize these interactions to the mesolimbic VTA.

Beneficial Effects of Apelin on Vascular Function in Patients With Central Obesity.

PubMed

Schinzari, Francesca; Veneziani, Augusto; Mores, Nadia; Barini, Angela; Di Daniele, Nicola; Cardillo, Carmine; Tesauro, Manfredi

2017-05-01

Patients with central obesity have impaired insulin-stimulated vasodilation and increased ET-1 (endothelin 1) vasoconstriction, which may contribute to insulin resistance and vascular damage. Apelin enhances insulin sensitivity and glucose disposal but also acts as a nitric oxide (NO)-dependent vasodilator and a counter-regulator of AT 1 (angiotensin [Ang] II type 1) receptor-induced vasoconstriction. We, therefore, examined the effects of exogenous (Pyr 1 )apelin on NO-mediated vasodilation and Ang II- or ET-1-dependent vasoconstrictor tone in obese patients. In the absence of hyperinsulinemia, forearm blood flow responses to graded doses of acetylcholine and sodium nitroprusside were not different during saline or apelin administration (both P >0.05). During intra-arterial infusion of regular insulin, however, apelin enhanced the vasodilation induced by both acetylcholine and nitroprusside (both P <0.05). Interestingly, the vasodilator effect of concurrent blockade of AT 1 (telmisartan) and AT 2 (PD 123,319) receptors was blunted by apelin (3±5% versus 32±9%; P <0.05). Similarly, during apelin administration, blockade of ET A receptors (BQ-123) resulted in lower vasodilator response than during saline (23±10% versus 65±12%; P <0.05). NO synthase inhibition by L-NMMA (l- N -monometylarginine) during the concurrent blockade of either Ang II or ET A receptors resulted in similar vasoconstriction in the absence or presence of apelin ( P >0.05). In conclusion, in patients with central obesity, apelin has favorable effects not only to improve insulin-stimulated endothelium-dependent and endothelium-independent vasodilator responses but also to blunt Ang II- and ET-1-dependent vasoconstriction by a mechanism not involving NO. Taken together, our results suggest that targeting the apelin system might favorably impact some hemodynamic abnormalities of insulin-resistant states like obesity. © 2017 American Heart Association, Inc.

GABA(A) receptor blockade in dorsomedial and ventromedial nuclei of the hypothalamus evokes panic-like elaborated defensive behaviour followed by innate fear-induced antinociception.

PubMed

Freitas, Renato Leonardo; Uribe-Mariño, Andrés; Castiblanco-Urbina, Maria Angélica; Elias-Filho, Daoud Hibraim; Coimbra, Norberto Cysne

2009-12-11

Dysfunction in the hypothalamic GABAergic system has been implicated in panic syndrome in humans. Furthermore, several studies have implicated the hypothalamus in the elaboration of pain modulation. Panic-prone states are able to be experimentally induced in laboratory animals to study this phenomenon. The aim of the present work was to investigate the involvement of medial hypothalamic nuclei in the organization of panic-like behaviour and the innate fear-induced oscillations of nociceptive thresholds. The blockade of GABA(A) receptors in the neuronal substrates of the ventromedial or dorsomedial hypothalamus was followed by elaborated defensive panic-like reactions. Moreover, innate fear-induced antinociception was consistently elicited after the escape behaviour. The escape responses organized by the dorsomedial and ventromedial hypothalamic nuclei were characteristically more elaborated, and a remarkable exploratory behaviour was recorded during GABA(A) receptor blockade in the medial hypothalamus. The motor characteristic of the elaborated defensive escape behaviour and the patterns of defensive alertness and defensive immobility induced by microinjection of the bicuculline either into the dorsomedial or into the ventromedial hypothalamus were very similar. This was followed by the same pattern of innate fear-induced antinociceptive response that lasted approximately 40 min after the elaborated defensive escape reaction in both cases. These findings suggest that dysfunction of the GABA-mediated neuronal system in the medial hypothalamus causes panic-like responses in laboratory animals, and that the elaborated escape behaviour organized in both dorsomedial and ventromedial hypothalamic nuclei are followed by significant innate-fear-induced antinociception. Our findings indicate that the GABA(A) receptor of dorsomedial and ventromedial hypothalamic nuclei are critically involved in the modulation of panic-like behaviour.

Effects of Adrenergic Blockade on Postpartum Adaptive Responses Induced by Labor Contractions

NASA Technical Reports Server (NTRS)

Ronca, April E.; Mills, N. A.; Lam, K. P.; Hayes, L. E.; Bowley, Susan M. (Technical Monitor)

2000-01-01

Prenatal exposure to labor contractions augments the expression of postnatal adaptive responses in newborn rats. Near-term rat fetuses exposed prenatally to simulated labor contractions and delivered by cesarean section breath and attach to nipples at greater frequencies than non-stimulated fetuses. Plasma NE (norepinephrine) and EPI (epinephrine) was significantly elevated in newborn rats exposed to vaginal birth or simulated labor contractions (compressions) with cesarean delivery as compared to non-compressed fetuses. In the present study, we investigated adrenergic mechanisms underlying labor-induced postnatal adaptive responses. Following spinal transection of late pregnant rat dams, fetuses were administered neurogenic or non-neurogenic adrenergic blockade: 1) bretylium (10 mg/kg sc) to prevent sympathetic neuronal release, 2) hexamethonium (30 mg/kg) to produce ganglionic blockade, 3) phenoxybenzanune (10mg/kg sc), an a- adrenergic receptor antagonist, 4) ICI-118551, 10 mg/kg sc), a b receptor antagonist, or 5) vehicle alone. Fetuses were either compressed (C) or non-compressed (NC) prior to cesarean delivery. a- and b- adrenergic antagonists reduced respiration and nipple attachment rates while sympathetic and vehicle alone did not. These results provide additional support for the hypothesis that adaptive neonatal effects of labor contractions are mediated by adrenal and extra-adrenal catecholamines.

A tryptophan-rich motif in the human parainfluenza virus type 2 V protein is critical for the blockade of toll-like receptor 7 (TLR7)- and TLR9-dependent signaling.

PubMed

Kitagawa, Yoshinori; Yamaguchi, Mayu; Zhou, Min; Komatsu, Takayuki; Nishio, Machiko; Sugiyama, Tsuyoshi; Takeuchi, Kenji; Itoh, Masae; Gotoh, Bin

2011-05-01

Plasmacytoid dendritic cells (pDCs) do not produce alpha interferon (IFN-α) unless viruses cause a systemic infection or overcome the first-line defense provided by conventional DCs and macrophages. We show here that even paramyxoviruses, whose infections are restricted to the respiratory tract, have a V protein able to prevent Toll-like receptor 7 (TLR7)- and TLR9-dependent IFN-α induction specific to pDCs. Mutational analysis of human parainfluenza virus type 2 demonstrates that the second Trp residue of the Trp-rich motif (Trp-X(3)-Trp-X(9)-Trp) in the C-terminal domain unique to V, a determinant for IRF7 binding, is critical for the blockade of TLR7/9-dependent signaling.

PD-1-PD-L1 immune-checkpoint blockade in malignant lymphomas.

PubMed

Wang, Yi; Wu, Ling; Tian, Chen; Zhang, Yizhuo

2018-02-01

Tumor cells can evade immune surveillance through overexpressing the ligands of checkpoint receptors on tumor cells or adjacent cells, leading T cells to anergy or exhaustion. Growing evidence of the interaction between tumor cells and microenvironment promoted the emergence of immune-checkpoint blockade. By targeting programmed cell death-1 (PD-1) pathway, cytotoxic activity of T cell is enhanced significantly and tumor cell lysis is induced subsequently. Currently, various antibodies against PD-1 and programmed death-ligand 1 (PD-L1) are under clinical studies in lymphomas. In this review, we outline the rationale for investigation of PD-1-PD-L1 immune-checkpoint blockade in lymphomas and discuss their prospect of applications in clinical treatment.

Effects of mineralocorticoid receptor blockade on empathy in patients with major depressive disorder.

PubMed

Wingenfeld, Katja; Kuehl, Linn K; Dziobek, Isabel; Roepke, Stefan; Otte, Christian; Hinkelmann, Kim

2016-10-01

The mineralocorticoid receptor (MR) is highly expressed in the hippocampus and prefrontal cortex and is involved in social cognition. We recently found that pharmacological stimulation of the MR enhances emotional empathy but does not affect cognitive empathy. In the current study, we examined whether blockade of the MR impairs empathy in patients with major depressive disorder (MDD) and healthy individuals. In a placebo-controlled study, we randomized 28 patients with MDD without psychotropic medication and 43 healthy individuals to either placebo or 300 mg spironolactone, a MR antagonist. Subsequently, all participants underwent two tests of social cognition, the Multifaceted Empathy Test (MET) and the Movie for the Assessment of Social Cognition (MASC), measuring cognitive and emotional facets of empathy. In the MET, we found no significant main effect of treatment or main effect of group for cognitive empathy but a highly significant treatment by group interaction (p < 0.01). Patients had higher cognitive empathy scores compared to controls in the placebo condition but not after spironolactone. Furthermore, in the spironolactone condition reduced cognitive empathy was seen in MDD patients but not in controls. Emotional empathy was not affected by MR blockade. In the MASC, no effect of spironolactone could be revealed. Depressed patients appear to exhibit greater cognitive empathy compared to healthy individuals. Blockade of MR reduced cognitive empathy in MDD patients to the level of healthy individuals. Future studies should further clarify the impact of MR functioning on different domains of social cognition in psychiatric patients.

TLR4/MyD88/NF-κB signaling and PPAR-γ within the paraventricular nucleus are involved in the effects of telmisartan in hypertension

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hong-Bao; Li, Xiang; Huo, Chan-Juan

Previous findings from our laboratory and others indicate that the main therapeutic effect of angiotensin II type 1 receptor (AT1-R) antagonists is to decrease blood pressure and exert anti-inflammatory effects in the cardiovascular system. In this study, we determined whether AT1-R antagonist telmisartan within the hypothalamic paraventricular nucleus (PVN) attenuates hypertension and hypothalamic inflammation via both the TLR4/MyD88/NF-κB signaling pathway and peroxisome proliferator-activated receptor-γ (PPAR-γ) in the PVN in hypertensive rats. Spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKY) rats were treated for 4 weeks through bilateral PVN infusion with the AT1-R antagonist telmisartan (TEL, 10 μg/h), or losartanmore » (LOS, 20 μg/h), or the PPAR-γ antagonist GW9662 (GW, 100 μg/h), or vehicle via osmotic minipump. Mean arterial pressure (MAP) was recorded by a tail-cuff occlusion method. PVN tissue and blood were collected for the measurement of AT1-R, PPAR-γ, pro-inflammatory cytokines (tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6), inducible nitric oxide synthase (iNOS), TLR4, MyD88, nuclear factor-kappa B (NF-κB) activity and plasma norepinephrine (NE), respectively. Hypertensive rats exhibited significantly higher level of AT1-R and lower level of PPAR-γ in the PVN. PVN treatment with TEL attenuated MAP, improved cardiac hypertrophy, reduced TNF-α, IL-1β, IL-6, iNOS levels, and plasma NE in SHR but not in WKY rats. These results were associated with reduced TLR4, MyD88 and NF-κB levels and increased PPAR-γ level in the PVN of hypertensive rats. Our findings suggest that TLR4/MyD88/NF-κB signaling and PPAR-γ within the PVN are involved in the beneficial effects of telmisartan in hypertension. - Highlights: • PVN infusion of TEL in spontaneously hypertensive rats is reported. • PVN infusion of TEL attenuates hypertension and proinflammatory cytokines in PVN. • PVN blockade of AT1-R attenuates sympathoexcitation and cardiac hypertrophy. • TLR4/MyD88/NF-κB signaling and PPAR-γ in PVN are involved in the effects of TEL.« less

Activation of µ-opioid receptors and block of KIR3 potassium channels and NMDA receptor conductance by l- and d-methadone in rat locus coeruleus

PubMed Central

Matsui, Aya; Williams, John T

2010-01-01

BACKGROUND AND PURPOSE Methadone activates opioid receptors to increase a potassium conductance mediated by G-protein-coupled, inwardly rectifying, potassium (KIR3) channels. Methadone also blocks KIR3 channels and N-methyl-D-aspartic acid (NMDA) receptors. However, the concentration dependence and stereospecificity of receptor activation and channel blockade by methadone on single neurons has not been characterized. EXPERIMENTAL APPROACH Intracellular and whole-cell recording were made from locus coeruleus neurons in brain slices and the activation of µ-opioid receptors and blockade of KIR3 and NMDA channels with l- and d-methadone was examined. KEY RESULTS The potency of l-methadone, measured by the amplitude of hyperpolarization was 16.5-fold higher than with d-methadone. A maximum hyperpolarization was caused by both enantiomers (∼30 mV); however, the maximum outward current measured with whole-cell voltage-clamp recording was smaller than the current induced by [Met]5enkephalin. The KIR3 conductance induced by activation of α2-adrenoceptors was decreased with high concentrations of l- and d-methadone (10–30 µM). In addition, methadone blocked the resting inward rectifying conductance (KIR). Both l- and d-methadone blocked the NMDA receptor-dependent current. The block of NMDA receptor-dependent current was voltage-dependent suggesting that methadone acted as a channel blocker. CONCLUSIONS AND IMPLICATIONS Methadone activated µ-opioid receptors at low concentrations in a stereospecific manner. KIR3 and NMDA receptor channel block was not stereospecific and required substantially higher concentrations. The separation in the concentration range suggests that the activation of µ-opioid receptors rather than the channel blocking properties mediate both the therapeutic and toxic actions of methadone. PMID:20659105

NIRS and indocyanine-green-determined muscle blood flow during exercise in humans

NASA Astrophysics Data System (ADS)

Boushel, Robert; Ide, Kojiro; Moller-Sorensen, Hasse; Fernandes, Alvito; Pott, Frank; Secher, Niels H.

1998-01-01

We present a method for determination of muscle blood flow (MBF) using near infrared spectroscopy (NIRS) with indocyanine green (ICG) as the tracer. MBF was quantified using the integrated arterial [ICG] and the accumulation of ICG in muscle. MBF was determined together with ICG-assessed cardiac output (CO) at rest and during incremental cycling. To further modify CO, the same work loads were performed after cardio-selective beta blockade by metoprolol. In one subject both MBF (9 to 110 ml (DOT) 100 g-1 (DOT) min-1) and CO increased linearly with work rate (8 to 19 l (DOT) min-1). Under beta blockade, both the increase in MBF and CO were lower: 5 to 70 ml (DOT) 100 g-1 (DOT) min-1 and 5 to 161 DOT min-1, respectively. During exercise with and without beta blockade, MBF increased with work load to represent a larger proportion of CO. Also, NIRS could detect an attenuated increase in MBF manifest by the restrained CO during leg exercise after cardio-selective beta blockade. Both observations indicate that NIRS detection of indocyanine green provides an estimate of muscle blood flow over the range from rest to intense exercise.

NIRS and indocyanine-green-determined muscle blood flow during exercise in humans

NASA Astrophysics Data System (ADS)

Boushel, Robert; Ide, Kojiro; Moller-Sorensen, Hasse; Fernandes, Alvito; Pott, Frank; Secher, Niels H.

1997-12-01

We present a method for determination of muscle blood flow (MBF) using near infrared spectroscopy (NIRS) with indocyanine green (ICG) as the tracer. MBF was quantified using the integrated arterial [ICG] and the accumulation of ICG in muscle. MBF was determined together with ICG-assessed cardiac output (CO) at rest and during incremental cycling. To further modify CO, the same work loads were performed after cardio-selective beta blockade by metoprolol. In one subject both MBF (9 to 110 ml (DOT) 100 g-1 (DOT) min-1) and CO increased linearly with work rate (8 to 19 l (DOT) min-1). Under beta blockade, both the increase in MBF and CO were lower: 5 to 70 ml (DOT) 100 g-1 (DOT) min-1 and 5 to 161 DOT min-1, respectively. During exercise with and without beta blockade, MBF increased with work load to represent a larger proportion of CO. Also, NIRS could detect an attenuated increase in MBF manifest by the restrained CO during leg exercise after cardio-selective beta blockade. Both observations indicate that NIRS detection of indocyanine green provides an estimate of muscle blood flow over the range from rest to intense exercise.

Brain regions mediating α3β4 nicotinic antagonist effects of 18-MC on nicotine self-administration

PubMed Central

Glick, Stanley D.; Sell, Elizabeth M.; McCallum, Sarah E; Maisonneuve, Isabelle M.

2011-01-01

18-methoxycoronaridine (18-MC), a putative anti-addictive agent, has been shown to decrease the self-administration of several drugs of abuse in rats. 18-MC is a potent antagonist at α3β4 nicotinic receptors. Consistent with high densities of α3β4 nicotinic receptors being located in the medial habenula and the interpeduncular nucleus, 18-MC has been shown to act in these regions to decrease both morphine and methamphetamine self-administration. The present study was conducted to determine if 18-MC’s effect on nicotine self-administration is mediated by acting in these same brain regions. Because moderate densities of α3β4 receptors occur in the dorsolateral tegmentum, ventral tegmental area, and basolateral amygdala, these brain areas were also examined as potential sites of action of 18-MC. Local administration of 18-MC into either the medial habenula, the basolateral amygdala or the dorsolateral tegmentum decreased nicotine self-administration. Surprisingly, local administration of 18-MC into the interpeduncular nucleus increased nicotine self-administration while local administration of 18-MC into the ventral tegmental area had no effect on nicotine self-administration. Similar effects were produced by local administration of either mecamylamine or conotoxin AuIB. These data are consistent with the hypothesis that 18-MC decreases nicotine self-administration by indirectly modulating the dopaminergic mesolimbic pathway via blockade of α3β4 nicotinic receptors in the medial habenula, basolateral amygdala, and dorsolateral tegmentum. The data also suggest that an action of 18-MC in the interpeduncular nucleus may attenuate aversive and/or depressive effects of nicotine. PMID:21871879

Predominance of AT(1) blockade over mas-mediated angiotensin-(1-7) mechanisms in the regulation of blood pressure and renin-angiotensin system in mRen2.Lewis rats.

PubMed

Varagic, Jasmina; Ahmad, Sarfaraz; VonCannon, Jessica L; Moniwa, Norihito; Brosnihan, K Bridget; Wysocki, Jan; Batlle, Daniel; Ferrario, Carlos M

2013-05-01

We investigated whether the antihypertensive actions of the angiotensin II (Ang II) receptor (AT(1)-R) blocker, olmesartan medoxomil, may in part be mediated by increased Ang-(1-7) in the absence of significant changes in plasma Ang II. mRen2.Lewis congenic hypertensive rats were administered either a vehicle (n = 14) or olmesartan (0.5 mg/kg/day; n = 14) by osmotic minipumps. Two weeks later, rats from both groups were further randomized to receive either the mas receptor antagonist A-779 (0.5 mg/kg/day; n = 7 per group) or its vehicle (n = 7 per group) for the next 4 weeks. Blood pressure was monitored by telemetry, and circulating and tissue components of the renin-angiotensin system (RAS) were measured at the completion of the experiments. Antihypertensive effects of olmesartan were associated with an increase in plasma renin concentration, plasma Ang I, Ang II, and Ang-(1-7), whereas serum aldosterone levels and kidney Ang II content were reduced. Preserved Ang-(1-7) content in kidneys was associated with increases of ACE2 protein but not activity and no changes on serum and kidney ACE activity. There was no change in cardiac peptide levels after olmesartan treatment. The antihypertensive effects of olmesartan were not altered by concomitant administration of the Ang-(1-7) receptor antagonist except for a mild further increase in plasma renin concentration. Our study highlights the independent regulation of RAS among plasma, heart, and kidney tissue in response to AT(1)-R blockade. Ang-(1-7) through the mas receptor does not mediate long-term effects of olmesartan besides counterbalancing renin release in response to AT(1)-R blockade.

NMDA and AMPA/kainate glutamatergic receptors in the prelimbic medial prefrontal cortex modulate the elaborated defensive behavior and innate fear-induced antinociception elicited by GABAA receptor blockade in the medial hypothalamus.

PubMed

de Freitas, Renato Leonardo; Salgado-Rohner, Carlos José; Biagioni, Audrey Francisco; Medeiros, Priscila; Hallak, Jaime Eduardo Cecílio; Crippa, José Alexandre S; Coimbra, Norberto Cysne

2014-06-01

The aim of the present study was to investigate the involvement of N-methyl-d-aspartate (NMDA) and amino-3-hydroxy-5-methyl-isoxazole-4-proprionate (AMPA)/kainate receptors of the prelimbic (PL) division of the medial prefrontal cortex (MPFC) on the panic attack-like reactions evoked by γ-aminobutyric acid-A receptor blockade in the medial hypothalamus (MH). Rats were pretreated with NaCl 0.9%, LY235959 (NMDA receptor antagonist), and NBQX (AMPA/kainate receptor antagonist) in the PL at 3 different concentrations. Ten minutes later, the MH was treated with bicuculline, and the defensive responses were recorded for 10 min. The antagonism of NMDA receptors in the PL decreased the frequency and duration of all defensive behaviors evoked by the stimulation of the MH and reduced the innate fear-induced antinociception. However, the pretreatment of the PL cortex with NBQX was able to decrease only part of defensive responses and innate fear-induced antinociception. The present findings suggest that the NMDA-glutamatergic system of the PL is critically involved in panic-like responses and innate fear-induced antinociception and those AMPA/kainate receptors are also recruited during the elaboration of fear-induced antinociception and in panic attack-related response. The activation of the glutamatergic neurotransmission of PL division of the MPFC during the elaboration of oriented behavioral reactions elicited by the chemical stimulation of the MH recruits mainly NMDA receptors in comparison with AMPA/kainate receptors.

Endocannabinoid signaling mediates oxytocin-driven social reward.

PubMed

Wei, Don; Lee, DaYeon; Cox, Conor D; Karsten, Carley A; Peñagarikano, Olga; Geschwind, Daniel H; Gall, Christine M; Piomelli, Daniele

2015-11-10

Marijuana exerts profound effects on human social behavior, but the neural substrates underlying such effects are unknown. Here we report that social contact increases, whereas isolation decreases, the mobilization of the endogenous marijuana-like neurotransmitter, anandamide, in the mouse nucleus accumbens (NAc), a brain structure that regulates motivated behavior. Pharmacological and genetic experiments show that anandamide mobilization and consequent activation of CB1 cannabinoid receptors are necessary and sufficient to express the rewarding properties of social interactions, assessed using a socially conditioned place preference test. We further show that oxytocin, a neuropeptide that reinforces parental and social bonding, drives anandamide mobilization in the NAc. Pharmacological blockade of oxytocin receptors stops this response, whereas chemogenetic, site-selective activation of oxytocin neurons in the paraventricular nucleus of the hypothalamus stimulates it. Genetic or pharmacological interruption of anandamide degradation offsets the effects of oxytocin receptor blockade on both social place preference and cFos expression in the NAc. The results indicate that anandamide-mediated signaling at CB1 receptors, driven by oxytocin, controls social reward. Deficits in this signaling mechanism may contribute to social impairment in autism spectrum disorders and might offer an avenue to treat these conditions.

CDK4/6 or MAPK blockade enhances efficacy of EGFR inhibition in oesophageal squamous cell carcinoma.

PubMed

Zhou, Jin; Wu, Zhong; Wong, Gabrielle; Pectasides, Eirini; Nagaraja, Ankur; Stachler, Matthew; Zhang, Haikuo; Chen, Ting; Zhang, Haisheng; Liu, Jie Bin; Xu, Xinsen; Sicinska, Ewa; Sanchez-Vega, Francisco; Rustgi, Anil K; Diehl, J Alan; Wong, Kwok-Kin; Bass, Adam J

2017-01-06

Oesophageal squamous cell carcinoma is a deadly disease where systemic therapy has relied upon empiric chemotherapy despite the presence of genomic alterations pointing to candidate therapeutic targets, including recurrent amplification of the gene encoding receptor tyrosine kinase epidermal growth factor receptor (EGFR). Here, we demonstrate that EGFR-targeting small-molecule inhibitors have efficacy in EGFR-amplified oesophageal squamous cell carcinoma (ESCC), but may become quickly ineffective. Resistance can occur following the emergence of epithelial-mesenchymal transition and by reactivation of the mitogen-activated protein kinase (MAPK) pathway following EGFR blockade. We demonstrate that blockade of this rebound activation with MEK (mitogen-activated protein kinase kinase) inhibition enhances EGFR inhibitor-induced apoptosis and cell cycle arrest, and delays resistance to EGFR monotherapy. Furthermore, genomic profiling shows that cell cycle regulators are altered in the majority of EGFR-amplified tumours and a combination of cyclin-dependent kinase 4/6 (CDK4/6) and EGFR inhibitors prevents the emergence of resistance in vitro and in vivo. These data suggest that upfront combination strategies targeting EGFR amplification, guided by adaptive pathway reactivation or by co-occurring genomic alterations, should be tested clinically.

Involvement of nitric oxide in lipopolysaccharide induced anorexia.

PubMed

Riediger, Thomas; Cordani, Caroline; Potes, Catarina Soares; Lutz, Thomas A

2010-11-01

Treatment with the bacterial endotoxin lipopolysaccharide (LPS) is a commonly used model to induce disease-related anorexia. Following LPS treatment inducible nitric oxide synthase (iNOS) is expressed in the hypothalamic arcuate nucleus (ARC), where nitric oxide (NO) inhibits orexigenic neurons. Intracellular STAT signaling is triggered by inflammatory stimuli and has been linked to the transcriptional regulation of iNOS. We evaluated whether pharmacological blockade of iNOS by the specific inhibitor 1400W attenuates LPS-induced anorexia. Furthermore, we hypothesized that the tolerance to the anorectic effect occurring after repeated LPS treatment is paralleled by a blunted STAT3 phosphorylation in the ARC. Rats treated with a subcutaneous injection of 1400W (10 mg/kg) showed an attenuated anorectic LPS response relative to control rats receiving only LPS (100 µg/kg; i.p.). Similarly, iNOS blockade attenuated LPS-induced adipsia, hyperthermia, inactivity and the concomitant drop in energy expenditure. While single LPS treatment increased STAT3 phosphorylation in the ARC, rats treated repeatedly with LPS showed no anorectic response and also no STAT3 phosphorylation in the ARC after the second and third LPS injections, respectively. Hence, pSTAT3 signaling in the ARC might be part of the intracellular cascades translating pro-inflammatory stimuli into suppression of food intake. The current findings substantiate a role of iNOS dependent NO formation in disease-related anorexia. Copyright © 2010 Elsevier Inc. All rights reserved.

Seeing is believing: anti-PD-1/PD-L1 monoclonal antibodies in action for checkpoint blockade tumor immunotherapy

PubMed Central

Tan, Shuguang; Zhang, Catherine W-H; Gao, George F

2016-01-01

Structural immunology, focusing on structures of host immune related molecules, enables the immunologists to see what the molecules look like, and more importantly, how they work together. Antibody-based PD-1/PD-L1 blockade therapy has achieved brilliant successes in clinical applications. The recent breakthrough of the complex structures of checkpoint blockade antibodies with their counterparts, pembrolizumab with PD-1 and avelumab with PD-L1, have made it clear how these monoclonal antibodies compete the binding of PD-1/PD-L1 and function to blockade the receptor-ligand interaction. Herein, we summarize the structural findings of these two reports and look into the future for how this information would facilitate the development of more efficient PD-1/PD-L1 targeting antibodies, small molecule drugs, and other protein or non-protein inhibitors. PMID:29263905

The evolution of renin-angiotensin blockade: angiotensin-converting enzyme inhibitors as the starting point.

PubMed

Sica, Domenic A

2010-04-01

The renin-angiotensin system has been a target in the treatment of hypertension for close to three decades. Several medication classes that block specific aspects of this system have emerged as useful therapies, including angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and, most recently, direct renin inhibitors. There has been a natural history to the development of each of these three drug classes, starting with their use as antihypertensive agents; thereafter, in each case they have been employed as end-organ protective agents. To date, there has been scant evidence to favor angiotensin receptor blockers or direct renin inhibitors over angiotensin-converting enzyme inhibitors in treating hypertension or in affording end-organ protection; thus, angiotensin-converting enzyme inhibitors remain the standard of care when renin-angiotensin system blockade is warranted.

It is time to reconsider the cardiovascular protection afforded by RAAS blockade -- overview of RAAS systems.

PubMed

Tsukamoto, Osamu; Kitakaze, Masafumi

2013-04-01

More than a century has passed since the renin-angiotensin-aldosterone system (RAAS) was discovered in 1897. Both circulatory and tissue RAAS have been found to be essential for regulation of the functions of the whole body, organs, tissues and cells. There is no doubt that the RAAS plays fundamental physiological roles in maintaining homeostasis, but it can also contribute to organ pathophysiology and tissue damages in some situations. Today, the usefulness of RAAS blockade is well-established in the management of a variety of cardiovascular disorders worldwide. However, the latest findings in this field are still providing us with new and unexpected insights into the pathophysiology of cardiovascular diseases. Such developments include dual blockade therapy with angiotensin I converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs), and a new class of RAAS blockers, renin inhibitors. These give us the opportunity to revisit the basic principles of the RAAS and reconsider the strategies of RAAS blockade for cardiovascular protection.

Recovery of NMDA receptor currents from MK-801 blockade is accelerated by Mg2+ and memantine under conditions of agonist exposure

PubMed Central

McKay, Sean; Bengtson, C. Peter; Bading, Hilmar; Wyllie, David J.A.; Hardingham, Giles E.

2013-01-01

MK-801 is a use-dependent NMDA receptor open channel blocker with a very slow off-rate. These properties can be exploited to ‘pre-block’ a population of NMDARs, such as synaptic ones, enabling the selective activation of a different population, such as extrasynaptic NMDARs. However, the usefulness of this approach is dependent on the stability of MK-801 blockade after washout. We have revisited this issue, and confirm that recovery of NMDAR currents from MK-801 blockade is enhanced by channel opening by NMDA, and find that it is further increased when Mg2+ is also present. In the presence of Mg2+, 50% recovery from MK-801 blockade is achieved after 10′ of 100 μM NMDA, or 30′ of 15 μM NMDA exposure. In Mg2+-free medium, NMDA-induced MK-801 dissociation was found to be much slower. Memantine, another PCP-site antagonist, could substitute for Mg2+ in accelerating the unblock of MK-801 in the presence of NMDA. This suggests a model whereby, upon dissociation from its binding site in the pore, MK-801 is able to re-bind in a process antagonized by Mg2+ or another PCP-site antagonist. Finally we show that even when all NMDARs are pre-blocked by MK-801, incubation of neurons with 100 μM NMDA in the presence of Mg2+ for 2.5 h triggers sufficient unblocking to kill >80% of neurons. We conclude that while synaptic MK-801 ‘pre-block’ protocols are useful for pharmacologically assessing synaptic vs. extrasynaptic contributions to NMDAR currents, or studying short-term effects, it is problematic to use this technique to attempt to study the effects of long-term selective extrasynaptic NMDAR activation. This article is part of the Special Issue entitled ‘Glutamate Receptor-Dependent Synaptic Plasticity’. PMID:23402996

Recovery of NMDA receptor currents from MK-801 blockade is accelerated by Mg2+ and memantine under conditions of agonist exposure.

PubMed

McKay, Sean; Bengtson, C Peter; Bading, Hilmar; Wyllie, David J A; Hardingham, Giles E

2013-11-01

MK-801 is a use-dependent NMDA receptor open channel blocker with a very slow off-rate. These properties can be exploited to 'pre-block' a population of NMDARs, such as synaptic ones, enabling the selective activation of a different population, such as extrasynaptic NMDARs. However, the usefulness of this approach is dependent on the stability of MK-801 blockade after washout. We have revisited this issue, and confirm that recovery of NMDAR currents from MK-801 blockade is enhanced by channel opening by NMDA, and find that it is further increased when Mg(2+) is also present. In the presence of Mg(2+), 50% recovery from MK-801 blockade is achieved after 10' of 100 μM NMDA, or 30' of 15 μM NMDA exposure. In Mg(2+)-free medium, NMDA-induced MK-801 dissociation was found to be much slower. Memantine, another PCP-site antagonist, could substitute for Mg(2+) in accelerating the unblock of MK-801 in the presence of NMDA. This suggests a model whereby, upon dissociation from its binding site in the pore, MK-801 is able to re-bind in a process antagonized by Mg(2+) or another PCP-site antagonist. Finally we show that even when all NMDARs are pre-blocked by MK-801, incubation of neurons with 100 μM NMDA in the presence of Mg(2+) for 2.5 h triggers sufficient unblocking to kill >80% of neurons. We conclude that while synaptic MK-801 'pre-block' protocols are useful for pharmacologically assessing synaptic vs. extrasynaptic contributions to NMDAR currents, or studying short-term effects, it is problematic to use this technique to attempt to study the effects of long-term selective extrasynaptic NMDAR activation. This article is part of the Special Issue entitled 'Glutamate Receptor-Dependent Synaptic Plasticity'. Copyright © 2013 Elsevier Ltd. All rights reserved.

Dietary restriction but not angiotensin II type 1 receptor blockade improves DNA damage-related vasodilator dysfunction in rapidly aging Ercc1Δ/- mice.

PubMed

Wu, Haiyan; van Thiel, Bibi S; Bautista-Niño, Paula K; Reiling, Erwin; Durik, Matej; Leijten, Frank P J; Ridwan, Yanto; Brandt, Renata M C; van Steeg, Harry; Dollé, Martijn E T; Vermeij, Wilbert P; Hoeijmakers, Jan H J; Essers, Jeroen; van der Pluijm, Ingrid; Danser, A H Jan; Roks, Anton J M

2017-08-01

DNA damage is an important contributor to endothelial dysfunction and age-related vascular disease. Recently, we demonstrated in a DNA repair-deficient, prematurely aging mouse model ( Ercc1 Δ/- mice) that dietary restriction (DR) strongly increases life- and health span, including ameliorating endothelial dysfunction, by preserving genomic integrity. In this mouse mutant displaying prominent accelerated, age-dependent endothelial dysfunction we investigated the signaling pathways involved in improved endothelium-mediated vasodilation by DR, and explore the potential role of the renin-angiotensin system (RAS). Ercc1 Δ/- mice showed increased blood pressure and decreased aortic relaxations to acetylcholine (ACh) in organ bath experiments. Nitric oxide (NO) signaling and phospho-Ser 1177 -eNOS were compromised in Ercc1 Δ / - DR improved relaxations by increasing prostaglandin-mediated responses. Increase of cyclo-oxygenase 2 and decrease of phosphodiesterase 4B were identified as potential mechanisms. DR also prevented loss of NO signaling in vascular smooth muscle cells and normalized angiotensin II (Ang II) vasoconstrictions, which were increased in Ercc1 Δ/- mice. Ercc1 Δ/ - mutants showed a loss of Ang II type 2 receptor-mediated counter-regulation of Ang II type 1 receptor-induced vasoconstrictions. Chronic losartan treatment effectively decreased blood pressure, but did not improve endothelium-dependent relaxations. This result might relate to the aging-associated loss of treatment efficacy of RAS blockade with respect to endothelial function improvement. In summary, DR effectively prevents endothelium-dependent vasodilator dysfunction by augmenting prostaglandin-mediated responses, whereas chronic Ang II type 1 receptor blockade is ineffective. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

p35 Regulates the CRM1-Dependent Nucleocytoplasmic Shuttling of Nuclear Hormone Receptor Coregulator-Interacting Factor 1 (NIF-1)

PubMed Central

Zhao, Xiao-Su; Fu, Wing-Yu; Chien, Winnie W. Y.; Li, Zhen; Fu, Amy K. Y.; Ip, Nancy Y.

2014-01-01

Cyclin-dependent kinase 5 (Cdk5) is a proline-directed serine/threonine kinase, which plays critical roles in a wide spectrum of neuronal functions including neuronal survival, neurite outgrowth, and synapse development and plasticity. Cdk5 activity is controlled by its specific activators: p35 or p39. While knockout studies reveal that Cdk5/p35 is critical for neuronal migration during early brain development, functions of Cdk5/p35 have been unraveled through the identification of the interacting proteins of p35, most of which are Cdk5/p35 substrates. However, it remains unclear whether p35 can regulate neuronal functions independent of Cdk5 activity. Here, we report that a nuclear protein, nuclear hormone receptor coregulator (NRC)-interacting factor 1 (NIF-1), is a new interacting partner of p35. Interestingly, p35 regulates the functions of NIF-1 independent of Cdk5 activity. NIF-1 was initially discovered as a transcriptional regulator that enhances the transcriptional activity of nuclear hormone receptors. Our results show that p35 interacts with NIF-1 and regulates its nucleocytoplasmic trafficking via the nuclear export pathway. Furthermore, we identified a nuclear export signal on p35; mutation of this site or blockade of the CRM1/exportin-dependent nuclear export pathway resulted in the nuclear accumulation of p35. Intriguingly, blocking the nuclear export of p35 attenuated the nuclear accumulation of NIF-1. These findings reveal a new p35-dependent mechanism in transcriptional regulation that involves the nucleocytoplasmic shuttling of transcription regulators. PMID:25329792

p35 regulates the CRM1-dependent nucleocytoplasmic shuttling of nuclear hormone receptor coregulator-interacting factor 1 (NIF-1).

PubMed

Zhao, Xiao-Su; Fu, Wing-Yu; Chien, Winnie W Y; Li, Zhen; Fu, Amy K Y; Ip, Nancy Y

2014-01-01

Cyclin-dependent kinase 5 (Cdk5) is a proline-directed serine/threonine kinase, which plays critical roles in a wide spectrum of neuronal functions including neuronal survival, neurite outgrowth, and synapse development and plasticity. Cdk5 activity is controlled by its specific activators: p35 or p39. While knockout studies reveal that Cdk5/p35 is critical for neuronal migration during early brain development, functions of Cdk5/p35 have been unraveled through the identification of the interacting proteins of p35, most of which are Cdk5/p35 substrates. However, it remains unclear whether p35 can regulate neuronal functions independent of Cdk5 activity. Here, we report that a nuclear protein, nuclear hormone receptor coregulator (NRC)-interacting factor 1 (NIF-1), is a new interacting partner of p35. Interestingly, p35 regulates the functions of NIF-1 independent of Cdk5 activity. NIF-1 was initially discovered as a transcriptional regulator that enhances the transcriptional activity of nuclear hormone receptors. Our results show that p35 interacts with NIF-1 and regulates its nucleocytoplasmic trafficking via the nuclear export pathway. Furthermore, we identified a nuclear export signal on p35; mutation of this site or blockade of the CRM1/exportin-dependent nuclear export pathway resulted in the nuclear accumulation of p35. Intriguingly, blocking the nuclear export of p35 attenuated the nuclear accumulation of NIF-1. These findings reveal a new p35-dependent mechanism in transcriptional regulation that involves the nucleocytoplasmic shuttling of transcription regulators.

Dopaminergic regulation of sleep and cataplexy in a murine model of narcolepsy.

PubMed

Burgess, Christian R; Tse, Gavin; Gillis, Lauren; Peever, John H

2010-10-01

To determine if the dopaminergic system modulates cataplexy, sleep attacks and sleep-wake behavior in narcoleptic mice. Hypocretin/orexin knockout (i.e., narcoleptic) and wild-type mice were administered amphetamine and specific dopamine receptor modulators to determine their effects on sleep, cataplexy and sleep attacks. Hypocretin knockout (n = 17) and wild-type mice (n = 21). Cataplexy, sleep attacks and sleep-wake behavior were identified using electroencephalogram, electromyogram and videography. These behaviors were monitored for 4 hours after an i.p. injection of saline, amphetamine and specific dopamine receptor modulators (D1- and D2-like receptor modulators). Amphetamine (2 mg/kg), which increases brain dopamine levels, decreased sleep attacks and cataplexy by 61% and 67%, suggesting that dopamine transmission modulates such behaviors. Dopamine receptor modulation also had powerful effects on sleep attacks and cataplexy. Activation (SKF 38393; 20 mg/kg) and blockade (SCH 23390; 1 mg/kg) of D1-like receptors decreased and increased sleep attacks by 77% and 88%, without affecting cataplexy. Pharmacological activation of D2-like receptors (quinpirole; 0.5 mg/kg) increased cataplectic attacks by 172% and blockade of these receptors (eticlopride; 1 mg/kg) potently suppressed them by 97%. Manipulation of D2-like receptors did not affect sleep attacks. We show that the dopaminergic system plays a role in regulating both cataplexy and sleep attacks in narcoleptic mice. We found that cataplexy is modulated by a D2-like receptor mechanism, whereas dopamine modulates sleep attacks by a D1-like receptor mechanism. These results support a role for the dopamine system in regulating sleep attacks and cataplexy in a murine model of narcolepsy.

RAS blockade with ARB and ACE inhibitors: current perspective on rationale and patient selection.

PubMed

Werner, Christian; Baumhäkel, Magnus; Teo, Koon K; Schmieder, Roland; Mann, Johannes; Unger, Thomas; Yusuf, Salim; Böhm, Michael

2008-07-01

Cardiovascular disease represents a continuum that starts with risk factors such as hypertension and progresses to atherosclerosis, target organ damage, and ultimately to myocardial infarction, heart failure, stroke or death. Renin-angiotensin system (RAS) blockade with angiotensin converting enzyme (ACE) inhibitors or angiotensin AT(1)-receptor blockers (ARBs) has turned out to be beneficial at all stages of this continuum. Both classes of agent can prevent or reverse endothelial dysfunction and atherosclerosis, thereby reducing the risk of cardiovascular events. Such a reduction has been shown mainly for ACE inhibitors in patients with coronary artery disease, but recent studies revealed that ARBs are not inferior in this respect. However, no such data are currently available on the combination of these drugs. Both ACE inhibitors and ARBs have been shown to reduce target organ damage in organs such as the kidney, brain and heart, and to decrease cardiovascular mortality and morbidity in patients with congestive heart failure. Experimental data point to an influence of ACE inhibitors and ARBs on the number and function of endothelial progenitor cells revealing additional mechanisms of action of these drugs. The VALIANT trial has shown equivalent effects of ARB valsartan and the ACE-inhibitor captopril in patients post myocardial infarction, but the dual RAS-blockade, compared to monotherapy, did not further reduce events. In secondary prevention, the most-recently published ONTARGET study provides evidence that on top of a better tolerability AT(1)-receptors antagonists are equal to ACE inhibitors in the prevention of clinical endpoints like cardiovascular mortality and morbidity, myocardial infarction and stroke. The combined RAS blockade, however, achieved no further benefits in vascular high-risk patients and was associated with more adverse events. In chronic heart failure, ValHeFT and CHARM-ADDED have shown that combined RAS inhibition with ACE inhibitor and valsartan or candesartan reduced morbidity and mortality in certain patient subgroups. Accumulating evidence also points to benefits of the combination therapy in individuals with proteinuric nephropathies. In conclusion, while combined RAS-inhibition is not generally indicated in patients along the cardio-reno-vascular continuum, it has already proven to be effective in heart failure patients with incomplete neuroendocrine blockade. In secondary prevention, monotherapy with either RAS inhibitor is equally efficacious. Furthermore, novel pharmacologic agents such as renin inhibitors may prove useful in preventing common side effects of RAS blockade such as angiotensin escape and AT(1)-receptor upregulation, giving clinicians additional therapeutic tools to optimally treat the individual patient.

Urothelium muscarinic activation phosphorylates CBSSer227 via cGMP/PKG pathway causing human bladder relaxation through H2S production

PubMed Central

d’Emmanuele di Villa Bianca, Roberta; Mitidieri, Emma; Fusco, Ferdinando; Russo, Annapina; Pagliara, Valentina; Tramontano, Teresa; Donnarumma, Erminia; Mirone, Vincenzo; Cirino, Giuseppe; Russo, Giulia; Sorrentino, Raffaella

2016-01-01

The urothelium modulates detrusor activity through releasing factors whose nature has not been clearly defined. Here we have investigated the involvement of H2S as possible mediator released downstream following muscarinic (M) activation, by using human bladder and urothelial T24 cell line. Carbachol stimulation enhances H2S production and in turn cGMP in human urothelium or in T24 cells. This effect is reversed by cysthationine-β-synthase (CBS) inhibition. The blockade of M1 and M3 receptors reverses the increase in H2S production in human urothelium. In T24 cells, the blockade of M1 receptor significantly reduces carbachol-induced H2S production. In the functional studies, the urothelium removal from human bladder strips leads to an increase in carbachol-induced contraction that is mimicked by CBS inhibition. Instead, the CSE blockade does not significantly affect carbachol-induced contraction. The increase in H2S production and in turn of cGMP is driven by CBS-cGMP/PKG-dependent phosphorylation at Ser227 following carbachol stimulation. The finding of the presence of this crosstalk between the cGMP/PKG and H2S pathway downstream to the M1/M3 receptor in the human urothelium further implies a key role for H2S in bladder physiopathology. Thus, the modulation of the H2S pathway can represent a feasible therapeutic target to develop drugs for bladder disorders. PMID:27509878

Urothelium muscarinic activation phosphorylates CBS(Ser227) via cGMP/PKG pathway causing human bladder relaxation through H2S production.

PubMed

d'Emmanuele di Villa Bianca, Roberta; Mitidieri, Emma; Fusco, Ferdinando; Russo, Annapina; Pagliara, Valentina; Tramontano, Teresa; Donnarumma, Erminia; Mirone, Vincenzo; Cirino, Giuseppe; Russo, Giulia; Sorrentino, Raffaella

2016-08-11

The urothelium modulates detrusor activity through releasing factors whose nature has not been clearly defined. Here we have investigated the involvement of H2S as possible mediator released downstream following muscarinic (M) activation, by using human bladder and urothelial T24 cell line. Carbachol stimulation enhances H2S production and in turn cGMP in human urothelium or in T24 cells. This effect is reversed by cysthationine-β-synthase (CBS) inhibition. The blockade of M1 and M3 receptors reverses the increase in H2S production in human urothelium. In T24 cells, the blockade of M1 receptor significantly reduces carbachol-induced H2S production. In the functional studies, the urothelium removal from human bladder strips leads to an increase in carbachol-induced contraction that is mimicked by CBS inhibition. Instead, the CSE blockade does not significantly affect carbachol-induced contraction. The increase in H2S production and in turn of cGMP is driven by CBS-cGMP/PKG-dependent phosphorylation at Ser(227) following carbachol stimulation. The finding of the presence of this crosstalk between the cGMP/PKG and H2S pathway downstream to the M1/M3 receptor in the human urothelium further implies a key role for H2S in bladder physiopathology. Thus, the modulation of the H2S pathway can represent a feasible therapeutic target to develop drugs for bladder disorders.

Histamine H3 receptor antagonists display antischizophrenic activities in rats treated with MK-801.

PubMed

Mahmood, Danish; Akhtar, Mohd; Jahan, Kausar; Goswami, Dipanjan

2016-09-01

Animal models based on N-methyl-d-aspartate receptor blockade have been extensively used for schizophrenia. Ketamine and MK-801 produce behaviors related to schizophrenia and exacerbated symptoms in patients with schizophrenia, which led to the use of PCP (phencyclidine)- and MK-801 (dizocilpine)-treated animals as models for schizophrenia. The study investigated the effect of subchronic dosing (once daily, 7 days) of histamine H3 receptor (H3R) antagonists, ciproxifan (CPX) (3 mg/kg, i.p.), and clobenpropit (CBP) (15 mg/kg, i.p.) on MK-801 (0.2 mg/kg, i.p.)-induced locomotor activity and also measured dopamine and histamine levels in rat's brain homogenates. The study also included clozapine (CLZ) (3.0 mg/kg, i.p.) and chlorpromazine (CPZ) (3.0 mg/kg, i.p.), the atypical and typical antipsychotic, respectively. Atypical and typical antipsychotic was used to serve as clinically relevant reference agents to compare the effects of the H3R antagonists. MK-801 significantly increased horizontal locomotor activity, which was reduced with CPX and CBP. MK-801-induced locomotor hyperactivity attenuated by CPX and CBP was comparable to CLZ and CPZ. MK-801 raised striatal dopamine level, which was reduced in rats pretreated with CPX and CBP. CPZ also significantly lowered striatal dopamine levels, although the decrease was less robust compared to CLZ, CPX, and CBP. MK-801 increased histamine content although to a lesser degree. Subchronic treatment with CPX and CBP exhibited further increased histamine levels in the hypothalamus compared to MK-801 treatment alone. Histamine H3 receptor agonist, R-α methylhistamine (10 mg/kg, i.p.), counteracted the effect of CPX and CBP. The present study shows the positive effects of CPX and CBP on MK-801-induced schizophrenia-like behaviors in rodents.

Beta-adrenergic and atrial natriuretic peptide interactions on human cardiovascular and metabolic regulation

PubMed Central

Birkenfeld, Andreas L.; Boschmann, Michael; Moro, Cedric; Adams, Frauke; Heusser, Karsten; Tank, Jens; Diedrich, André; Schroeder, Christoph; Franke, Gabi; Berlan, Michel; Luft, Friedrich C.; Lafontan, Max; Jordan, Jens

2006-01-01

Context Atrial natriuretic peptide (ANP) has well known cardiovascular effects and modifies lipid and carbohydrate metabolism in humans. Objective To determine the metabolic and cardiovascular interaction of beta-adrenergic receptors and ANP. Design Cross over study, conducted 2004–2005 Setting Academic clinical research center Patients Ten healthy, young, male subjects (BMI 24±1 kg/m2) Intervention We infused intravenously incremental ANP doses (6.25, 12.5, and 25 ng/kg/min) with and without propranolol (0.20 mg/kg in divided doses followed by 0.033 mg/kg/h infusion). Metabolism was monitored through venous blood sampling, intramuscular and subcutaneous microdialysis and indirect calorimetry. Cardiovascular changes where monitored by continuous ECG and beat-by-beat blood pressure recordings. Main outcome measures Venous NEFA, glycerol, glucose, insulin; microdialysate glucose, glycerol, lactate, pyruvate. Results ANP increased heart rate dose dependently. Beta-adrenergic receptor blockade abolished the response. ANP elicited a dose-dependent increase in serum non-esterified fatty acid and glycerol concentrations. The response was not suppressed with propranolol. Venous glucose and insulin concentrations increased with ANP, both, without or with propranolol. ANP induced lipid mobilization in subcutaneous adipose tissue. In skeletal muscle, microdialysate lactate increased while the lactate to pyruvate ratio decreased, both, with and without propranolol. Higher ANP doses increased lipid oxidation while energy expenditure remained unchanged. Propranolol tended to attenuate the increase in lipid oxidation. Conclusions Selected cardiovascular ANP effects are at least partly mediated by beta-adrenergic receptor stimulation. ANP induced changes in lipid mobilization and glycolysis are mediated by another mechanism, presumably stimulation of natriuretic peptide receptors whereas substrate oxidation might be modulated through adrenergic mechanisms. PMID:16984990

Intrathecal P/Q- and R-type calcium channel blockades on spinal substance P release and c-Fos expression

PubMed Central

Terashima, Tetsuji; Xu, Qinghao; Yamaguchi, Shigeki; Yaksh, Tony L.

2013-01-01

Intrathecal (IT) studies have shown that several voltage sensitive calcium channels (VSCCs), such as the L-, N- and T-type may play roles in nociception and that of these only the N-type regulates primary afferent substance P (SP) release. However, the actions of other VSCCs at the spinal level are not well known. We investigated the roles of spinal P/Q- and R-type VSCCs, by IT administration of R-type (SNX-482) and P/Q-type (ω-agatoxin IVA) VSCC blockers on intraplantar formalin-evoked flinching, SP release from primary afferents and c-Fos expression in spinal dorsal horn. Intraplantar injection of formalin (2.5%, 50 µL) produced an intense, characteristic biphasic paw flinching response. In rats with IT catheters, IT SNX-482 (0.5 µg) reduced formalin-evoked paw flinching in both phase 1 and 2 compared with vehicle. Intraplantar formalin caused robust neurokinin 1 receptor (NK1r) internalization (indicating SP release) and c-Fos expression in the ipsilateral dorsal horn, which were blocked by IT SNX-482. IT ω-agatoxin IVA (0.03, 0.125 and 0.5 µg) did not reduce formalin-evoked paw flinching or c-Fos expression at any doses, with higher doses resulting in motor dysfunction. Thus, we demonstrated that blockade of spinal R-type, but not P/Q type VSCCs attenuated formalin-induced pain behavior, NK1r internalization and c-Fos expression in the superficial dorsal horn. This study supports a role for Cav2.3 in presynaptic neurotransmitter release from peptidergic nociceptive afferents and pain behaviors. PMID:23810829

NMDA receptor gating of information flow through the striatum in vivo.

PubMed

Pomata, Pablo E; Belluscio, Mariano A; Riquelme, Luis A; Murer, M Gustavo

2008-12-10

A role of NMDA receptors in corticostriatal synaptic plasticity is widely acknowledged. However, the conditions that allow NMDA receptor activation in the striatum in vivo remain obscure. Here we show that NMDA receptors contribute to sustain the membrane potential of striatal medium spiny projection neurons close to threshold during spontaneous UP states in vivo. Moreover, we found that the blockade of striatal NMDA receptors reduces markedly the spontaneous firing of ensembles of medium spiny neurons during slow waves in urethane-anesthetized rats. We speculate that recurrent activation of NMDA receptors during UP states allows off-line information flow through the striatum and system level consolidation during habit formation.

Ionotropic and metabotropic glutamate receptor mediation of glucocorticoid-induced apoptosis in hippocampal cells and the neuroprotective role of synaptic N-methyl-D-aspartate receptors.

PubMed

Lu, J; Goula, D; Sousa, N; Almeida, O F X

2003-01-01

Glutamate receptors have been proposed to mediate the apoptotic actions of glucocorticoids in hippocampal cells. To further analyze the role of glutamate receptors in this process, we pretreated primary hippocampal cells from neonatal (postnatal day 4) rats with antagonists of ionotropic glutamate receptor (iGluR) and metabotropic glutamate receptor (mGluR) antagonists before exposure to the specific glucocorticoid receptor agonist dexamethasone (DEX) at a dose of 1 microM. Dizocilpine (MK801; a general N-methyl-D-aspartic acid [NMDA] receptor antagonist, NMDAR antagonist) and ifenprodil (a specific ligand of the NMDAR 2B subunit, NR2B), were used to block iGluR; (RS)-alpha-ethyl-4-carboxyphenylglycine (E4CPG) and (RS)-alpha-cyclopropyl-4-phosphonophenyl-glycine (CPPG) were employed as I/II (E4CPG) and II/III (CPPG) mGluR antagonists. Blockade of iGluR resulted in a significant attenuation of DEX-induced cell death; the finding that ifenprodil exerted a similar potency to MK801 demonstrates the involvement of NR2B receptors in glucocorticoid-induced cell death. Apoptosis accounted for a significant amount of the cell loss observed, as detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling histochemistry for the in situ labeling of DNA breaks; apoptotic cells were distinguished from necrosis on the basis of morphological criteria, including chromatin condensation, membrane blebbing and presence of apoptotic bodies. Treatment with E4CPG and CPPG completely abolished the apoptotic response to DEX, thus showing the additional contribution of mGluR to the phenomenon. Further, dose-response studies with NMDA revealed that whereas high (10 microM) doses of NMDA themselves elicit cytotoxic responses, low (1-5 microM) concentrations of NMDA can effectively oppose DEX-induced cell death. Interestingly, the neuroprotective actions of low dose NMDA stimulation were abolished when either synaptic or extrasynaptic NMDA receptors were blocked with MK801 in combination with the GABA receptor antagonist bicuculline (synaptic) or ifenprodil (extrasynaptic). In summary, the present data show that both iGluR and mGluR mediate the neurotoxic effects of glucocorticoids on hippocampal cells and that pre-treatment with low doses of NMDA, by acting on synaptic and extrasynaptic receptors, render hippocampal cells less vulnerable to glucocorticoid insults.

Losartan reduces the immediate and sustained increases in muscle sympathetic nerve activity after hyperacute intermittent hypoxia.

PubMed

Jouett, Noah P; Moralez, Gilbert; Raven, Peter B; Smith, Michael L

2017-04-01

Obstructive sleep apnea (OSA) is characterized by intermittent hypoxemia, which produces elevations in sympathetic nerve activity (SNA) and associated hypertension in experimental models that persist beyond the initial exposure. We tested the hypotheses that angiotensin receptor blockade in humans using losartan attenuates the immediate and immediately persistent increases in 1 ) SNA discharge and 2 ) mean arterial pressure (MAP) after hyperacute intermittent hypoxia training (IHT) using a randomized, placebo-controlled, repeated-measures experimental design. We measured ECG and photoplethysmographic arterial pressure in nine healthy human subjects, while muscle SNA (MSNA) was recorded in seven subjects using microneurography. Subjects were exposed to a series of hypoxic apneas in which they inhaled two to three breaths of nitrogen, followed by a 20-s apnea and 40 s of room air breathing every minute for 20 min. Hyperacute IHT produced substantial and persistent elevations in MSNA burst frequency (baseline: 15.3 ± 1.8, IHT: 24 ± 1.5, post-IHT 20.0 ± 1.3 bursts/min, all P < 0.01) and MAP (baseline: 89.2 ± 3.3, IHT: 92.62 ± 3.1, post-IHT: 93.83 ± 3.1 mmHg, all P < 0.02). Losartan attenuated the immediate and sustained increases in MSNA (baseline: 17.3 ± 2.5, IHT: 18.6 ± 2.2, post-IHT 20.0 ± 1.3 bursts/min, all P < 0.001) and MAP (baseline: 81.9 ± 2.6, IHT: 81.1 ± 2.8, post-IHT: 81.3 ± 3.0 mmHg, all P > 0.70). This investigation confirms the role of angiotensin II type 1a receptors in the immediate and persistent sympathoexcitatory and pressor responses to IHT. NEW & NOTEWORTHY This study demonstrates for the first time in humans that losartan, an angiotensin receptor blocker (ARB), abrogates the acute and immediately persistent increases in muscle sympathetic nerve activity and arterial pressure in response to acute intermittent hypoxia. This investigation, along with others, provides important beginning translational evidence for using ARBs in treatment of the intermittent hypoxia observed in obstructive sleep apnea patients. Copyright © 2017 the American Physiological Society.

Recent progress in the development of protein-protein interaction inhibitors targeting androgen receptor-coactivator binding in prostate cancer.

PubMed

Biron, Eric; Bédard, François

2016-07-01

The androgen receptor (AR) is a key regulator for the growth, differentiation and survival of prostate cancer cells. Identified as a primary target for the treatment of prostate cancer, many therapeutic strategies have been developed to attenuate AR signaling in prostate cancer cells. While frontline androgen-deprivation therapies targeting either the production or action of androgens usually yield favorable responses in prostate cancer patients, a significant number acquire treatment resistance. Known as the castration-resistant prostate cancer (CRPC), the treatment options are limited for this advanced stage. It has been shown that AR signaling is restored in CRPC due to many aberrant mechanisms such as AR mutations, amplification or expression of constitutively active splice-variants. Coregulator recruitment is a crucial regulatory step in AR signaling and the direct blockade of coactivator binding to AR offers the opportunity to develop therapeutic agents that would remain effective in prostate cancer cells resistant to conventional endocrine therapies. Structural analyses of the AR have identified key surfaces involved in protein-protein interaction with coregulators that have been recently used to design and develop promising AR-coactivator binding inhibitors. In this review we will discuss the design and development of small-molecule inhibitors targeting the AR-coactivator interactions for the treatment of prostate cancer. Copyright © 2015 Elsevier Ltd. All rights reserved.

GABA interneurons mediate the rapid antidepressant-like effects of scopolamine

PubMed Central

Wohleb, Eric S.; Wu, Min; Gerhard, Danielle M.; Taylor, Seth R.; Picciotto, Marina R.; Alreja, Meenakshi; Duman, Ronald S.

2016-01-01

Major depressive disorder (MDD) is a recurring psychiatric illness that causes substantial health and socioeconomic burdens. Clinical reports have revealed that scopolamine, a nonselective muscarinic acetylcholine receptor antagonist, produces rapid antidepressant effects in individuals with MDD. Preclinical models suggest that these rapid antidepressant effects can be recapitulated with blockade of M1-type muscarinic acetylcholine receptors (M1-AChR); however, the cellular mechanisms underlying activity-dependent synaptic and behavioral responses to scopolamine have not been determined. Here, we demonstrate that the antidepressant-like effects of scopolamine are mediated by GABA interneurons in the medial prefrontal cortex (mPFC). Both GABAergic (GAD67+) interneurons and glutamatergic (CaMKII+) interneurons in the mPFC expressed M1-AChR. In mice, viral-mediated knockdown of M1-AChR specifically in GABAergic neurons, but not glutamatergic neurons, in the mPFC attenuated the antidepressant-like effects of scopolamine. Immunohistology and electrophysiology showed that somatostatin (SST) interneurons in the mPFC express M1-AChR at higher levels than parvalbumin interneurons. Moreover, knockdown of M1-AChR in SST interneurons in the mPFC demonstrated that M1-AChR expression in these neurons is required for the rapid antidepressant-like effects of scopolamine. These data indicate that SST interneurons in the mPFC are a promising pharmacological target for developing rapid-acting antidepressant therapies. PMID:27270172

GABA interneurons mediate the rapid antidepressant-like effects of scopolamine.

PubMed

Wohleb, Eric S; Wu, Min; Gerhard, Danielle M; Taylor, Seth R; Picciotto, Marina R; Alreja, Meenakshi; Duman, Ronald S

2016-07-01

Major depressive disorder (MDD) is a recurring psychiatric illness that causes substantial health and socioeconomic burdens. Clinical reports have revealed that scopolamine, a nonselective muscarinic acetylcholine receptor antagonist, produces rapid antidepressant effects in individuals with MDD. Preclinical models suggest that these rapid antidepressant effects can be recapitulated with blockade of M1-type muscarinic acetylcholine receptors (M1-AChR); however, the cellular mechanisms underlying activity-dependent synaptic and behavioral responses to scopolamine have not been determined. Here, we demonstrate that the antidepressant-like effects of scopolamine are mediated by GABA interneurons in the medial prefrontal cortex (mPFC). Both GABAergic (GAD67+) interneurons and glutamatergic (CaMKII+) interneurons in the mPFC expressed M1-AChR. In mice, viral-mediated knockdown of M1-AChR specifically in GABAergic neurons, but not glutamatergic neurons, in the mPFC attenuated the antidepressant-like effects of scopolamine. Immunohistology and electrophysiology showed that somatostatin (SST) interneurons in the mPFC express M1-AChR at higher levels than parvalbumin interneurons. Moreover, knockdown of M1-AChR in SST interneurons in the mPFC demonstrated that M1-AChR expression in these neurons is required for the rapid antidepressant-like effects of scopolamine. These data indicate that SST interneurons in the mPFC are a promising pharmacological target for developing rapid-acting antidepressant therapies.

The dopamine-D2-receptor agonist ropinirole dose-dependently blocks the Ca2+-triggered permeability transition of mitochondria.

PubMed

Parvez, Suhel; Winkler-Stuck, Kirstin; Hertel, Silvia; Schönfeld, Peter; Siemen, Detlef

2010-01-01

Ropinirole, an agonist of the post-synaptic dopamine D2-receptor, exerts neuroprotective activity. The mechanism is still under discussion. Assuming that this neuroprotection might be associated with inhibition of the apoptotic cascade underlying cell death, we examined a possible effect of ropinirole on the permeability transition pore (mtPTP) in the mitochondrial inner membrane. Using isolated rat liver mitochondria, the effect of ropinirole was studied on Ca2+-triggered large amplitude swelling, membrane depolarization and cytochrome c release. In addition, the effect of ropinirole on oxidation of added, membrane-impermeable NADH was investigated. The results revealed doubtlessly, that ropinirole can inhibit permeability transition. In patch-clamp experiments on mitoplasts, we show directly that ropinirole interacts with the mtPTP. Thus, ropinirole reversibly inhibits the opening of mtPTP with an IC50 of 3.4 microM and a Hill coefficient of 1.3. In both systems (i.e. energized mitochondria and mitoplasts) the inhibitory effect on permeability transition was attenuated by increasing concentrations of inorganic phosphate. In addition, we showed with antimycin A-treated mitochondria that ropinirole failed to suppress respiratory chain-linked reactive oxygen species release. In conclusion, our data suggest that the neuroprotective activity of ropinirole is due to the blockade of the Ca2+-triggered permeability transition. Copyright © 2010 Elsevier B.V. All rights reserved.

Hindbrain GLP-1 receptor mediation of cisplatin-induced anorexia and nausea.

PubMed

De Jonghe, Bart C; Holland, Ruby A; Olivos, Diana R; Rupprecht, Laura E; Kanoski, Scott E; Hayes, Matthew R

2016-01-01

While chemotherapy-induced nausea and vomiting are clinically controlled in the acute (<24 h) phase following treatment, the anorexia, nausea, fatigue, and other illness-type behaviors during the delayed phase (>24 h) of chemotherapy are largely uncontrolled. As the hindbrain glucagon-like peptide-1 (GLP-1) system contributes to energy balance and mediates aversive and stressful stimuli, here we examine the hypothesis that hindbrain GLP-1 signaling mediates aspects of chemotherapy-induced nausea and reductions in feeding behavior in rats. Specifically, hindbrain GLP-1 receptor (GLP-1R) blockade, via 4th intracerebroventricular (ICV) exendin-(9-39) injections, attenuates the anorexia, body weight reduction, and pica (nausea-induced ingestion of kaolin clay) elicited by cisplatin chemotherapy during the delayed phase (48 h) of chemotherapy-induced nausea. Additionally, the present data provide evidence that the central GLP-1-producing preproglucagon neurons in the nucleus tractus solitarius (NTS) of the caudal brainstem are activated by cisplatin during the delayed phase of chemotherapy-induced nausea, as cisplatin led to a significant increase in c-Fos immunoreactivity in NTS GLP-1-immunoreactive neurons. These data support a growing body of literature suggesting that the central GLP-1 system may be a potential pharmaceutical target for adjunct anti-emetics used to treat the delayed-phase of nausea and emesis, anorexia, and body weight loss that accompany chemotherapy treatments. Copyright © 2015 Elsevier Inc. All rights reserved.

Alpha adrenergic regulation of celiac blood flow and plasma catecholamine response during acute heat stress in fed cockerels.

PubMed

Bottje, W G; Harrison, P C

1986-08-01

Hubbard cockerels with chronically implanted electromagnetic blood flow probes on the celiac artery were used to establish a relationship between changes in postprandial celiac mean blood flow (MBF) and plasma catecholamines during a acute heat exposure. Five min after the elevation of ambient temperature from 25 to 37 C, there were concomitant reductions (P less than .05) in celiac MBF, norepinephrine (NE), and heart rate (HR). After 50 min of heat stress, rectal temperature (Tr), respiratory rate (RR), plasma epinephrine (E), and celiac vascular resistance (CVR) were significantly greater (P less than .05) than preheat stress thermoneutral control values. During the thermoneutral recovery period, all parameters returned to values comparable to preheat exposure control with the exception of NE, which tended (P less than .1) to remain lower. To determine the role of the sympathetic nervous system in regulating postprandial celiac MBF during acute heat exposure, chronically instrumented cockerels were infused with phenoxybenzamine, an alpha-adrenergic receptor-blocking agent. Alpha-receptor blockade attenuated both postprandial intestinal hyperemia under thermoneutral conditions as well as the heat-induced reduction of postprandial celiac MBF. The results of these studies implicate the sympathetic nervous system in the regulation of postprandial celiac MBF in heat-stressed cockerels and indicate a possible alpha-adrenergic-mediated mechanism involved in postprandial intestinal hyperemia.

Present and Future in the Treatment of Diabetic Kidney Disease

PubMed Central

de Arriba, Gabriel

2015-01-01

Diabetic kidney disease is the leading cause of end-stage renal disease. Albuminuria is recognized as the most important prognostic factor for chronic kidney disease progression. For this reason, blockade of renin-angiotensin system remains the main recommended strategy, with either angiotensin converting enzyme inhibitors or angiotensin II receptor blockers. However, other antiproteinuric treatments have begun to be studied, such as direct renin inhibitors or aldosterone blockers. Beyond antiproteinuric treatments, other drugs such as pentoxifylline or bardoxolone have yielded conflicting results. Finally, alternative pathogenic pathways are being explored, and emerging therapies including antifibrotic agents, endothelin receptor antagonists, or transcription factors show promising results. The aim of this review is to explain the advances in newer agents to treat diabetic kidney disease, along with the background of the renin-angiotensin system blockade. PMID:25945357

Noradrenergic facilitation of shock-probe defensive burying in lateral septum of rats, and modulation by chronic treatment with desipramine.

PubMed

Bondi, Corina O; Barrera, Gabriel; Lapiz, M Danet S; Bedard, Tania; Mahan, Amy; Morilak, David A

2007-03-30

We have previously shown that acute stress-induced release of norepinephrine (NE) facilitates anxiety-like behavioral responses to stress, such as reduction in open-arm exploration on the elevated-plus maze and in social behavior on the social interaction test. Since these responses represent inhibition of ongoing behavior, it is important to also address whether NE facilitates a response that represents an activation of behavior. Correspondingly, it is unknown how a chronic elevation in tonic steady-state noradrenergic (NA) neurotransmission induced by NE reuptake blockade might alter this acute modulatory function, a regulatory process that may be pertinent to the anxiolytic effects of NE reuptake blockers such as desipramine (DMI). Therefore, in this study, we investigated noradrenergic modulation of the shock-probe defensive burying response in the lateral septum (LS). In experiment 1, shock-probe exposure induced an acute 3-fold increase in NE levels measured in LS of male Sprague-Dawley rats by microdialysis. Shock-probe exposure also induced a modest rise in plasma ACTH, taken as an indicator of perceived stress, that returned to baseline more rapidly in rats that were allowed to bury the probe compared to rats prevented from burying by providing them with minimal bedding, indicating that the active defensive burying behavior is an effective coping strategy that reduces the impact of acute shock probe-induced stress. In experiment 2, blockade of either alpha(1)- or beta-adrenergic receptors in LS by local antagonist microinjection immediately before testing reduced defensive burying and increased immobility. In the next experiment, chronic DMI treatment increased basal extracellular NE levels in LS, and attenuated the acute shock probe-induced increase in NE release in LS relative to baseline. Chronic DMI treatment decreased shock-probe defensive burying behavior in a time-dependent manner, apparent only after 2 weeks or more of drug treatment. Moreover, rats treated chronically with DMI showed no significant rise of plasma ACTH in response to shock-probe exposure. Thus, acute stress-induced release of NE in LS facilitated defensive burying, an active, adaptive behavioral coping response. Chronic treatment with the NE reuptake blocker and antidepressant drug DMI attenuated acute noradrenergic facilitation of the active burying response, and also attenuated the level of perceived stress driving that response. These results suggest that long-term regulation of the acute modulatory function of NE by chronic treatment with reuptake blockers may contribute to the mechanisms by which such drugs exert their anxiolytic effects in the treatment of stress-related psychiatric conditions, including depression and anxiety.

Undiscovered role of endogenous thromboxane A2 in activation of cardiac sympathetic afferents during ischaemia

PubMed Central

Fu, Liang-Wu; Guo, Zhi-Ling; Longhurst, John C

2008-01-01

Myocardial ischaemia activates blood platelets, which in turn stimulate cardiac sympathetic afferents, leading to chest pain and sympathoexcitatory reflex cardiovascular responses. Previous studies have shown that activated platelets stimulate ischaemically sensitive cardiac sympathetic afferents, and that thromboxane A2 (TxA2) is one of the mediators released from activated platelets during myocardial ischaemia. The present study tested the hypothesis that endogenous TxA2 stimulates cardiac afferents during ischaemia through direct activation of TxA2 (TP) receptors coupled with the phospholipase C–protein kinase C (PLC–PKC) cellular pathway. Nerve activity of single unit cardiac sympathetic afferents was recorded from the left sympathetic chain or rami communicantes (T2–T5) in anaesthetized cats. Single fields of 39 afferents (conduction velocity = 0.27–3.65 m s−1) were identified in the left or right ventricle initially with mechanical stimulation and confirmed with a stimulating electrode. Five minutes of myocardial ischaemia stimulated all 39 cardiac afferents (8 Aδ-, 31 C-fibres) and the responses of these 39 afferents to chemical stimuli were further studied in the following four protocols. In the first protocol, 2.5, 5 and 10 μg of the TxA2 mimetic, U46619, injected into the left atrium (LA), stimulated seven ischaemically sensitive cardiac afferents in a dose-dependent manner. Second, BM13,177, a selective TxA2 receptor antagonist, abolished the responses of six afferents to 5 μg of U46619 injected into the left atrium and attenuated the ischaemia-related increase in activity of seven other afferents by 44%. In contrast, cardiac afferents, in the absence of TP receptor blockade responded consistently to repeated administration of U46619 (n = 6) and to recurrent myocardial ischaemia (n = 7). In the fourth protocol, administration of PKC-(19–36), a selective PKC inhibitor, attenuated the responses of six other cardiac afferents to U46619 by 38%. Finally, using an immunohistochemical staining approach, we observed that TP receptors were expressed in cardiac sensory neurons in thoracic dorsal root ganglia. Taken together, these data indicate that endogenous TxA2 contributes to the activation of cardiac afferents during myocardial ischaemia through direct stimulation of TP receptors probably located in the cardiac sensory nervous system and that the stimulating effect of TxA2 on cardiac afferents is dependent, at least in part, upon the PLC–PKC cellular pathway. PMID:18483073

Enhanced Requirement for TNFR2 in Graft Rejection Mediated by Low Affinity Memory CD8+ T Cells During Heterologous Immunity

PubMed Central

Krummey, Scott M.; Chen, Ching-Wen; Guasch, Sara A.; Liu, Danya; Wagener, Maylene; Larsen, Christian P; Ford, Mandy L.

2016-01-01

The affinity of a T cell receptor (TCR) binding to peptide:MHC profoundly impacts the phenotype and function of effector and memory cell differentiation. Little is known about the effect of low affinity priming on memory cell generation and function, which is particularly important in heterologous immunity, when microbe-specific T cells cross-react with allogeneic antigen and mediate graft rejection. We found that low affinity primed memory CD8+ T cells produced high levels of TNF ex vivo in response to heterologous rechallenge compared to high affinity primed memory T cells. Low affinity secondary effectors significantly upregulated TNFR2 on the cell surface and contained a higher frequency of TNFR2hi proliferating cells. Low affinity primed secondary effectors concurrently downregulated TNF production. Importantly, blockade of TNFR2 attenuated graft rejection in low but not high affinity primed animals. These data establish a functional connection between TNF signaling and TCR priming affinity and have implications for the immunomodulation of pathogenic T cell responses during transplantation. PMID:27481849

Design of short peptides to block BTLA/HVEM interactions for promoting anticancer T-cell responses

PubMed Central

Spodzieja, Marta; Lach, Sławomir; Iwaszkiewicz, Justyna; Cesson, Valérie; Kalejta, Katarzyna; Olive, Daniel; Michielin, Olivier; Speiser, Daniel E.; Zoete, Vincent

2017-01-01

Antibody based immune-checkpoint blockade therapy is a major breakthrough in oncology, leading to clinical benefit for cancer patients. Among the growing family of inhibitory receptors, the B and T lymphocyte attenuator (BTLA), which interacts with herpes virus entry mediator (HVEM), is a promising target for immunotherapy. Indeed, BTLA inhibits T-cell proliferation and cytokine production. The crystal structure of the BTLA/HVEM complex has shown that the HVEM(26–38) fragment is directly involved in protein binding. We designed and analyzed the capacity of several analogs of this fragment to block the ligation between BTLA and HVEM, using competitive ELISA and cellular assay. We found that the HVEM(23–39) peptide can block BTLA/HVEM ligation. However, the blocking ability was due to the Cys encompassed in this peptide and that even free cysteine targeted the BTLA protein and blocked its interaction with HVEM. These data highlight a Cys-related artefact in vitro, which should be taken in consideration for future development of BTLA/HVEM blocking compounds. PMID:28594868

Adenosine A2A Receptor Blockade or Deletion Diminishes Fibrocyte Accumulation in the Skin in a Murine Model of Scleroderma, Bleomycin-induced Fibrosis

PubMed Central

Katebi, Majid; Fernandez, Patricia; Chan, Edwin S. L.; Cronstein, Bruce N.

2015-01-01

Peripheral blood fibrocytes are a newly identified circulating leukocyte subpopulation that migrates into injured tissue where it may display fibroblast-like properties and participate in wound healing and fibrosis of skin and other organs. Previous studies in our lab demonstrated that A2A receptor-deficient and A2A antagonist-treated mice were protected from developing bleomycin-induced dermal fibrosis, thus the aim of this study was to determine whether the adenosine A2A receptor regulates recruitment of fibrocytes to the dermis in this bleomycin-induced model of dermal fibrosis. Sections of skin from normal mice and bleomycin-treated wild type, A2A knockout and A2A antagonist-treated mice were stained for Procollagen α2 Type I and CD34 and the double stained cells, fibrocytes, were counted in the tissue sections. There were more fibrocytes in the dermis of bleomycin-treated mice than normal mice and the increase was abrogated by deletion or blockade of adenosine A2A receptors. Because fibrocytes play a central role in tissue fibrosis these results suggest that diminished adenosine A2A receptor-mediated recruitment of fibrocytes into tissue may play a role in the pathogenesis of fibrosing diseases of the skin. Moreover, these results provide further evidence that adenosine A2A receptors may represent a new target for the treatment of such fibrosing diseases as scleroderma or nephrogenic fibrosing dermopathy. PMID:18709547

[Effect of non-selective alpha-adrenergic receptor antagonist nicergoline on the activity of neurons in the ventral lateral thalamic nucleus].

PubMed

Lukhanina, O P; Pil'kevych, N A

2005-01-01

In experiments on rats microionophoretic administration of nicergoline mainly showed the dual effect on the background activity of the ventrolateral thalamic nucleus (VL) neurons and their reactions evoked by the superior cerebellum peduncle stimulation: inhibitory under weak (2-10 nA) and excitatory under stronger (20-40 nA) currents. Microionophoresis (25 nA) of nicergoline led to decrease of the postexcitatory inhibitory processes during paired stimulation of the cerebellum fibers. Paired-pulse ratio (number of spikes in the short-latency neuronal responses elicited by the second pulse/number of spikes by the first pulse) increased, which support a presynaptic mode of drug action. Hence excitatory effect of nicergoline may be related to the blockade of the presynaptic alpha2-receptors, while inhibitory effect by the blockade of the postsynaptic alphal-receptors. Present data reveal the essential participation of the alpha-adrenoreceptor system in the modulation of background and evoked neuronal activity of the motor thalamus. The possible role of noradrenergic denervation in the development of movement disorders accompanying Parkinson's disease is discussed.

Loss of Macrophage Low-Density Lipoprotein Receptor-Related Protein 1 Confers Resistance to the Antiatherogenic Effects of Tumor Necrosis Factor-α Inhibition.

PubMed

Zhu, Lin; Giunzioni, Ilaria; Tavori, Hagai; Covarrubias, Roman; Ding, Lei; Zhang, Youmin; Ormseth, Michelle; Major, Amy S; Stafford, John M; Linton, MacRae F; Fazio, Sergio

2016-08-01

Antiatherosclerotic effects of tumor necrosis factor-α (TNF-α) blockade in patients with systemic inflammatory states are not conclusively demonstrated, which suggests that effects depend on the cause of inflammation. Macrophage LRP1 (low-density lipoprotein receptor-related protein 1) and apoE contribute to inflammation through different pathways. We studied the antiatherosclerosis effects of TNF-α blockade in hyperlipidemic mice lacking either LRP1 (MΦLRP1(-/-)) or apoE from macrophages. Lethally irradiated low-density lipoprotein receptor (LDLR)(-/-) mice were reconstituted with bone marrow from either wild-type, MΦLRP1(-/-), apoE(-/-) or apoE(-/-)/MΦLRP1(-/-)(DKO) mice, and then treated with the TNF-α inhibitor adalimumab while fed a Western-type diet. Adalimumab reduced plasma TNF-α concentration, suppressed blood ly6C(hi) monocyte levels and their migration into the lesion, and reduced lesion cellularity and inflammation in both wild-type→LDLR(-/-) and apoE(-/-)→LDLR(-/-) mice. Overall, adalimumab reduced lesion burden by 52% to 57% in these mice. Adalimumab reduced TNF-α and blood ly6C(hi) monocyte levels in MΦLRP1(-/-)→LDLR(-/-) and DKO→LDLR(-/-) mice, but it did not suppress ly6C(hi) monocyte migration into the lesion or atherosclerosis progression. Our results show that TNF-α blockade exerts antiatherosclerotic effects that are dependent on the presence of macrophage LRP1. © 2016 American Heart Association, Inc.

Interaction of Tacrine at M1 and M2 Cholinoceptors in Guinea Pig Brain

DTIC Science & Technology

1993-01-01

NUMBERS cholinoceptors in Guinea Pig Brain 6 AUTHOR Maria Szilagyi and Wai-Man Lau 7 FOAMING ORG KES/eADORENESS DEFENCE SCIENCE AND S PEFORMING Wa REPO...rat heart muscarinic receptors using 3 Freeman SE, Lau W-M, Szilagyi M: M2 muscarinic receptors. Neurosci the new M2 selective antagonist Blockade of

Systemic Blockade of D2-Like Dopamine Receptors Facilitates Extinction of Conditioned Fear in Mice

ERIC Educational Resources Information Center

Ponnusamy, Ravikumar; Nissim, Helen A.; Barad, Mark

2005-01-01

Extinction of conditioned fear in animals is the explicit model of behavior therapy for human anxiety disorders, including panic disorder, obsessive-compulsive disorder, and post-traumatic stress disorder. Based on previous data indicating that fear extinction in rats is blocked by quinpirole, an agonist of dopamine D2 receptors, we hypothesized…

Alcohol and Caffeine: The Perfect Storm

PubMed Central

O'Brien, Mary Claire

2011-01-01

Although it is widely believed that caffeine antagonizes the intoxicating effects of alcohol, the molecular mechanisms underlying their interaction are incompletely understood. It is known that both caffeine and alcohol alter adenosine neurotransmission, but the relationship is complex, and may be dose dependent. In this article, we review the available literature on combining caffeine and alcohol. Ethical constraints prohibit laboratory studies that would mimic the high levels of alcohol intoxication achieved by many young people in real-world settings, with or without the addition of caffeine. We propose a possible neurochemical mechanism for the increase in alcohol consumption and alcohol-related consequences that have been observed in persons who simultaneously consume caffeine. Caffeine is a nonselective adenosine receptor antagonist. During acute alcohol intake, caffeine antagonizes the “unwanted” effects of alcohol by blocking the adenosine A1 receptors that mediate alcohol's somnogenic and ataxic effects. The A1 receptor–mediated “unwanted” anxiogenic effects of caffeine may be ameliorated by alcohol-induced increase in the extracellular concentration of adenosine. Moreover, by means of interactions between adenosine A2A and dopamine D2 receptors, caffeine-mediated blockade of adenosine A2A receptors can potentiate the effects of alcohol-induced dopamine release. Chronic alcohol intake decreases adenosine tone. Caffeine may provide a “treatment” for the withdrawal effects of alcohol by blocking the effects of upregulated A1 receptors. Finally, blockade of A2A receptors by caffeine may contribute to the reinforcing effects of alcohol. PMID:24761263

Hindbrain leptin and glucagon-like-peptide-1 receptor signaling interact to suppress food intake in an additive fashion

PubMed Central

Zhao, Shiru; Kanoski, Scott E.; Yan, Jianqun; Grill, Harvey J.; Hayes, Matthew R.

2011-01-01

Background The physiological control of feeding behavior involves modulation of the intake inhibitory effects of gastrointestinal satiation signaling via endogenous hindbrain leptin receptor (LepR) and glucagon-like-peptide-1 receptor (GLP-1R) activation. Design and Results Using a variety of dose-combinations of hindbrain delivered (4th icv) leptin and the GLP-1R agonist exendin-4, experiments demonstrate that hindbrain LepR and GLP-1R signaling interact to control food intake and body weight in an additive fashion. In addition, the maximum intake suppressive response that could be achieved by 4th icv leptin alone in non-obese rats (~33%) was shown to be further suppressed when exendin-4 was co-administered. Importantly, it was determined that the interaction between hindbrain LepR signaling and GLP-1R signaling is relevant to endogenous food intake control, as hindbrain GLP-1R blockade by the selective antagonist exendin-(9–39) attenuated the intake inhibitory effects of hindbrain leptin delivery. Conclusions Collectively, the findings reported here show that hindbrain LepR and GLP-1R activation interact in at least an additive fashion to control food intake and body weight. As evidence is accumulating that combination pharmacotherapies offer greater sustained food intake and body weight suppression in obese individuals when compared to mono-drug therapies or lifestyle modifications alone, these findings highlight the need for further examination of combined CNS GLP-1R and LepR signaling as a potential drug target for obesity treatment. PMID:22249232

Substance P contributes to rapidly adapting receptor responses to pulmonary venous congestion in rabbits.

PubMed Central

Bonham, A C; Kott, K S; Ravi, K; Kappagoda, C T; Joad, J P

1996-01-01

1. This study tested the hypothesis that substance P stimulates rapidly adapting receptors (RARs), contributes to the increase in RAR activity produced by mild pulmonary congestion, and evokes an augmented response from RARs when combined with near-threshold levels of pulmonary congestion. 2. RAR activity, peak tracheal pressure, arterial blood pressure and left atrial pressure were measured in paralysed, anaesthetized and ventilated rabbits. Substance P was given i.v. in one-half log incremental doses to a maximum of 3 micrograms kg-1. Mild pulmonary congestion was produced by inflating a balloon in the left atrium to increase left atrial pressure by 5 mmHg. Near-threshold levels of pulmonary congestion were produced by increasing left atrial pressure by 2 mmHg. 3. Substance P produced dose-dependent increases in RAR activity. The highest dose given increased the activity from 1.3 +/- 0.5 to 11.0 +/- 3.1 impulses bin-1. Increases in left atrial pressure of 5 mmHg increased RAR activity from 3.8 +/- 1.4 to 14.7 +/- 3.9 impulses bin-1. Blockade of NK1 receptors with CP 96345 significantly attenuated RAR responses to substance P and to mild pulmonary congestion. 4. Doses of substance P, which alone had no effect, stimulated the RARs when delivered during near-threshold levels of pulmonary congestion. 5. The findings suggest that substance P augments the stimulatory effect of mild pulmonary congestion on RAR activity, most probably by enhancing hydraulically induced microvascular leak. Images Figure 6 PMID:8735708

Embryonic GABA(B) receptor blockade alters cell migration, adult hypothalamic structure, and anxiety- and depression-like behaviors sex specifically in mice.

PubMed

Stratton, Matthew S; Staros, Michelle; Budefeld, Tomaz; Searcy, Brian T; Nash, Connor; Eitel, Chad; Carbone, David; Handa, Robert J; Majdic, Gregor; Tobet, Stuart A

2014-01-01

Neurons of the paraventricular nucleus of the hypothalamus (PVN) regulate the hypothalamic- pituitary-adrenal (HPA) axis and the autonomic nervous system. Females lacking functional GABA(B) receptors because of a genetic disruption of the R1 subunit have altered cellular characteristics in and around the PVN at birth. The genetic disruption precluded appropriate assessments of physiology or behavior in adulthood. The current study was conducted to test the long term impact of a temporally restricting pharmacological blockade of the GABA(B) receptor to a 7-day critical period (E11-E17) during embryonic development. Experiments tested the role of GABA(B) receptor signaling in fetal development of the PVN and later adult capacities for adult stress related behaviors and physiology. In organotypic slices containing fetal PVN, there was a female specific, 52% increase in cell movement speeds with GABA(B) receptor antagonist treatment that was consistent with a sex-dependent lateral displacement of cells in vivo following 7 days of fetal exposure to GABA(B) receptor antagonist. Anxiety-like and depression-like behaviors, open-field activity, and HPA mediated responses to restraint stress were measured in adult offspring of mothers treated with GABA(B) receptor antagonist. Embryonic exposure to GABA(B) receptor antagonist resulted in reduced HPA axis activation following restraint stress and reduced depression-like behaviors. There was also increased anxiety-like behavior selectively in females and hyperactivity in males. A sex dependent response to disruptions of GABA(B) receptor signaling was identified for PVN formation and key aspects of physiology and behavior. These changes correspond to sex specific prevalence in similar human disorders, namely anxiety disorders and hyperactivity.

Angiopoietin receptor Tie2 is required for vein specification and maintenance via regulating COUP-TFII

PubMed Central

Chu, Man; Li, Taotao; Shen, Bin; Cao, Xudong; Zhong, Haoyu; Zhang, Luqing; Zhou, Fei; Ma, Wenjuan; Jiang, Haijuan; Xie, Pancheng; Liu, Zhengzheng; Dong, Ningzheng; Xu, Ying; Zhao, Yun; Xu, Guoqiang; Lu, Peirong; Luo, Jincai; Wu, Qingyu; Alitalo, Kari; Koh, Gou Young; Adams, Ralf H; He, Yulong

2016-01-01

Mechanisms underlying the vein development remain largely unknown. Tie2 signaling mediates endothelial cell (EC) survival and vascular maturation and its activating mutations are linked to venous malformations. Here we show that vein formation are disrupted in mouse skin and mesentery when Tie2 signals are diminished by targeted deletion of Tek either ubiquitously or specifically in embryonic ECs. Postnatal Tie2 attenuation resulted in the degeneration of newly formed veins followed by the formation of haemangioma-like vascular tufts in retina and venous tortuosity. Mechanistically, Tie2 insufficiency compromised venous EC identity, as indicated by a significant decrease of COUP-TFII protein level, a key regulator in venogenesis. Consistently, angiopoietin-1 stimulation increased COUP-TFII in cultured ECs, while Tie2 knockdown or blockade of Tie2 downstream PI3K/Akt pathway reduced COUP-TFII which could be reverted by the proteasome inhibition. Together, our results imply that Tie2 is essential for venous specification and maintenance via Akt mediated stabilization of COUP-TFII. DOI: http://dx.doi.org/10.7554/eLife.21032.001 PMID:28005008

Regulation of prostate cancer by hormone-responsive G protein-coupled receptors.

PubMed

Wang, Wei; Chen, Zhao-Xia; Guo, Dong-Yu; Tao, Ya-Xiong

2018-06-15

Regulation of prostate cancer by androgen and androgen receptor (AR), and blockade of AR signaling by AR antagonists and steroidogenic enzyme inhibitors have been extensively studied. G protein-coupled receptors (GPCRs) are a family of membrane receptors that regulate almost all physiological processes. Nearly 40% of FDA-approved drugs in the market target GPCRs. A variety of GPCRs that mediate reproductive function have been demonstrated to be involved in the regulation of prostate cancer. These GPCRs include gonadotropin-releasing hormone receptor, luteinizing hormone receptor, follicle-stimulating hormone receptor, relaxin receptor, ghrelin receptor, and kisspeptin receptor. We highlight here GPCR regulation of prostate cancer by these GPCRs. Further therapeutic approaches targeting these GPCRs for the treatment of prostate cancer are summarized. Copyright © 2018. Published by Elsevier Inc.

The necessity and effectiveness of mineralocorticoid receptor antagonist in the treatment of diabetic nephropathy.

PubMed

Sato, Atsuhisa

2015-06-01

Diabetes mellitus is a major cause of chronic kidney disease (CKD), and diabetic nephropathy is the most common primary disease necessitating dialysis treatment in the world including Japan. Major guidelines for treatment of hypertension in Japan, the United States and Europe recommend the use of angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers, which suppress the renin-angiotensin system (RAS), as the antihypertensive drugs of first choice in patients with coexisting diabetes. However, even with the administration of RAS inhibitors, failure to achieve adequate anti-albuminuric, renoprotective effects and a reduction in cardiovascular events has also been reported. Inadequate blockade of aldosterone may be one of the reasons why long-term administration of RAS inhibitors may not be sufficiently effective in patients with diabetic nephropathy. This review focuses on treatment in diabetic nephropathy and discusses the significance of aldosterone blockade. In pre-nephropathy without overt nephropathy, a mineralocorticoid receptor antagonist can be used to enhance the blood pressure-lowering effects of RAS inhibitors, improve insulin resistance and prevent clinical progression of nephropathy. In CKD categories A2 and A3, the addition of a mineralocorticoid receptor antagonist to an RAS inhibitor can help to maintain 'long-term' antiproteinuric and anti-albuminuric effects. However, in category G3a and higher, sufficient attention must be paid to hyperkalemia. Mineralocorticoid receptor antagonists are not currently recommended as standard treatment in diabetic nephropathy. However, many studies have shown promise of better renoprotective effects if mineralocorticoid receptor antagonists are appropriately used.

Rupture Forces among Human Blood Platelets at different Degrees of Activation

PubMed Central

Nguyen, Thi-Huong; Palankar, Raghavendra; Bui, Van-Chien; Medvedev, Nikolay; Greinacher, Andreas; Delcea, Mihaela

2016-01-01

Little is known about mechanics underlying the interaction among platelets during activation and aggregation. Although the strength of a blood thrombus has likely major biological importance, no previous study has measured directly the adhesion forces of single platelet-platelet interaction at different activation states. Here, we filled this void first, by minimizing surface mediated platelet-activation and second, by generating a strong adhesion force between a single platelet and an AFM cantilever, preventing early platelet detachment. We applied our setup to measure rupture forces between two platelets using different platelet activation states, and blockade of platelet receptors. The rupture force was found to increase proportionally to the degree of platelet activation, but reduced with blockade of specific platelet receptors. Quantification of single platelet-platelet interaction provides major perspectives for testing and improving biocompatibility of new materials; quantifying the effect of drugs on platelet function; and assessing the mechanical characteristics of acquired/inherited platelet defects. PMID:27146004