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Sample records for a1 receptor blockade

  1. 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.

  2. 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.

  3. Orexin-1 receptor blockade dysregulates REM sleep in the presence of orexin-2 receptor antagonism

    PubMed Central

    Dugovic, Christine; Shelton, Jonathan E.; Yun, Sujin; Bonaventure, Pascal; Shireman, Brock T.; Lovenberg, Timothy W.

    2014-01-01

    In accordance with the prominent role of orexins in the maintenance of wakefulness via activation of orexin-1 (OX1R) and orexin-2 (OX2R) receptors, various dual OX1/2R antagonists have been shown to promote sleep in animals and humans. While selective blockade of OX2R seems to be sufficient to initiate and prolong sleep, the beneficial effect of additional inhibition of OX1R remains controversial. The relative contribution of OX1R and OX2R to the sleep effects induced by a dual OX1/2R antagonist was further investigated in the rat, and specifically on rapid eye movement (REM) sleep since a deficiency of the orexin system is associated with narcolepsy/cataplexy based on clinical and pre-clinical data. As expected, the dual OX1/2R antagonist SB-649868 was effective in promoting non-REM (NREM) and REM sleep following oral dosing (10 and 30 mg/kg) at the onset of the dark phase. However, a disruption of REM sleep was evidenced by a more pronounced reduction in the onset of REM as compared to NREM sleep, a marked enhancement of the REM/total sleep ratio, and the occurrence of a few episodes of direct wake to REM sleep transitions (REM intrusion). When administered subcutaneously, the OX2R antagonist JNJ-10397049 (10 mg/kg) increased NREM duration whereas the OX1R antagonist GSK-1059865 (10 mg/kg) did not alter sleep. REM sleep was not affected either by OX2R or OX1R blockade alone, but administration of the OX1R antagonist in combination with the OX2R antagonist induced a significant reduction in REM sleep latency and an increase in REM sleep duration at the expense of the time spent in NREM sleep. These results indicate that additional blockade of OX1R to OX2R antagonism elicits a dysregulation of REM sleep by shifting the balance in favor of REM sleep at the expense of NREM sleep that may increase the risk of adverse events. Translation of this hypothesis remains to be tested in the clinic. PMID:24592208

  4. Programmed death receptor-1/programmed death receptor ligand-1 blockade after transient lymphodepletion to treat myeloma.

    PubMed

    Kearl, Tyce J; Jing, Weiqing; Gershan, Jill A; Johnson, Bryon D

    2013-06-01

    Early phase clinical trials targeting the programmed death receptor-1/ligand-1 (PD-1/PD-L1) pathway to overcome tumor-mediated immunosuppression have reported promising results for a variety of cancers. This pathway appears to play an important role in the failure of immune reactivity to malignant plasma cells in multiple myeloma patients, as the tumor cells express relatively high levels of PD-L1, and T cells show increased PD-1 expression. In the current study, we demonstrate that PD-1/PD-L1 blockade with a PD-L1-specific Ab elicits rejection of a murine myeloma when combined with lymphodepleting irradiation. This particular combined approach by itself has not previously been shown to be efficacious in other tumor models. The antitumor effect of lymphodepletion/anti-PD-L1 therapy was most robust when tumor Ag-experienced T cells were present either through cell transfer or survival after nonmyeloablative irradiation. In vivo depletion of CD4 or CD8 T cells completely eliminated antitumor efficacy of the lymphodepletion/anti-PD-L1 therapy, indicating that both T cell subsets are necessary for tumor rejection. Elimination of myeloma by T cells occurs relatively quickly as tumor cells in the bone marrow were nearly nondetectable by 5 d after the first anti-PD-L1 treatment, suggesting that antimyeloma reactivity is primarily mediated by preactivated T cells, rather than newly generated myeloma-reactive T cells. Anti-PD-L1 plus lymphodepletion failed to improve survival in two solid tumor models, but demonstrated significant efficacy in two hematologic malignancy models. In summary, our results support the clinical testing of lymphodepletion and PD-1/PD-L1 blockade as a novel approach for improving the survival of patients with multiple myeloma.

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. Endothelin B receptor blockade attenuates pulmonary vasodilation in oxygen-ventilated fetal lambs.

    PubMed

    Ivy, D Dunbar; Lee, Dong-Seok; Rairigh, Robyn L; Parker, Thomas A; Abman, Steven H

    2004-01-01

    Endothelin-1 (ET-1) contributes to the regulation of pulmonary vascular tone in the normal ovine fetus and in models of perinatal pulmonary hypertension. In the fetal lamb lung, the effects of ET-1 depend on the balance of at least two endothelin receptor subtypes: ETA and ETB. ETA receptors are located on smooth muscle cells and mediate vasoconstriction and smooth muscle proliferation. Stimulation of endothelial ETB receptors causes vasodilation through release of nitric oxide and also functions to remove ET-1 from the circulation. However, whether activation of ETB receptors contributes to the fall in pulmonary vascular tone at birth is unknown. To determine the role of acute ETB receptor blockade in pulmonary vasodilation in response to birth-related stimuli, we studied the hemodynamic effects of selective ETB receptor blockade with BQ-788 during mechanical ventilation with low (<10%) and high FiO2 (100%) in near-term fetal sheep. Intrapulmonary infusion of BQ-788 did not change left pulmonary artery (LPA) blood flow and pulmonary vascular resistance (PVR) at baseline. In comparison with controls, BQ-788 treatment attenuated the rise in LPA flow with low and high FiO2 ventilation (p <0.001 vs. control for each FiO2 concentration). PVR progressively decreased during mechanical ventilation with low and high FiO2 in both groups, but PVR remained higher after BQ-788 treatment throughout the study period (p <0.001). We conclude that selective ETB receptor blockade attenuates pulmonary vasodilation at birth. We speculate that ETB receptor stimulation contributes to pulmonary vasodilation at birth in the ovine fetus.

  10. The effects of AMPA receptor blockade on resting magnetoencephalography recordings.

    PubMed

    Routley, Bethany C; Singh, Krish D; Hamandi, Khalid; Muthukumaraswamy, Suresh D

    2017-12-01

    The ionotropic N-methyl-D-aspartate and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors of the glutamatergic neurotransmitter system are of fundamental importance to healthy brain function. Neuroimaging studies in humans have previously been conducted using various drugs that interact with N-methyl-D-aspartate glutamate receptors, but no such studies have investigated AMPA receptor signalling. The recent approval of perampanel (Fycompa) for use in humans provides a means to specifically study the role of AMPA receptors in the pharmacological basis of neuroimaging signals. Twenty male subjects participated in this placebo-controlled crossover study that consisted of two study days separated by a minimum two-week washout period. On one occasion participants ingested a 6 mg dose of perampanel, and on the other a placebo. Ten minutes of wakeful rest was recorded before and after each dose using magnetoencephalography. Subjective ratings of intoxication were significantly higher following drug than placebo. Cluster-based randomisation testing of sensor-level magnetoencephalography data showed significant drug-induced increases in low frequency power (1-4 Hz, 4-8 Hz, 8-13 Hz, 13-30 Hz), along with a significant decrease in the high gamma range (50-90 Hz). We also observed selective increases in functional connectivity in the alpha and beta bands. The findings are consistent with preclinical work and are similar to the spectral profile of other anti-epileptic drugs.

  11. 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…

  12. Opiate receptor blockade on human granulosa cells inhibits VEGF release.

    PubMed

    Lunger, Fabian; Vehmas, Anni P; Fürnrohr, Barbara G; Sopper, Sieghart; Wildt, Ludwig; Seeber, Beata

    2016-03-01

    The objectives of this study were to determine whether the main opioid receptor (OPRM1) is present on human granulosa cells and if exogenous opiates and their antagonists can influence granulosa cell vascular endothelial growth factor (VEGF) production via OPRM1. Granulosa cells were isolated from women undergoing oocyte retrieval for IVF. Complementary to the primary cells, experiments were conducted using COV434, a well-characterized human granulosa cell line. Identification and localization of opiate receptor subtypes was carried out using Western blot and flow cytometry. The effect of opiate antagonist on granulosa cell VEGF secretion was assessed by enzyme-linked immunosorbent assay. For the first time, the presence of OPRM1 on human granulosa cells is reported. Blocking of opiate signalling using naloxone, a specific OPRM1 antagonist, significantly reduced granulosa cell-derived VEGF levels in both COV434 and granulosa-luteal cells (P < 0.01). The presence of opiate receptors and opiate signalling in granulosa cells suggest a possible role in VEGF production. Targeting this signalling pathway could prove promising as a new clinical option in the prevention and treatment of ovarian hyperstimulation syndrome. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  13. 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.

  14. 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

  15. 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

  16. Selective cognitive impairments associated with NMDA receptor blockade in humans.

    PubMed

    Rowland, Laura M; Astur, Robert S; Jung, Rex E; Bustillo, Juan R; Lauriello, John; Yeo, Ronald A

    2005-03-01

    Hypofunction of the N-methyl-D-aspartate receptor (NMDAR) may be involved in the pathophysiology of schizophrenia. NMDAR antagonists like ketamine induce schizophrenia-like features in humans. In rodent studies, NMDAR antagonism impairs learning by disrupting long-term potentiation (LTP) in the hippocampus. This study investigated the effects of ketamine on spatial learning (acquisition) vs retrieval in a virtual Morris water task in humans. Verbal fluency, working memory, and learning and memory of verbal information were also assessed. Healthy human subjects participated in this double-blinded, placebo-controlled study. On two separate occasions, ketamine/placebo was administered and cognitive tasks were assessed in association with behavioral ratings. Ketamine impaired learning of spatial and verbal information but retrieval of information learned prior to drug administration was preserved. Schizophrenia-like symptoms were significantly related to spatial and verbal learning performance. Ketamine did not significantly impair attention, verbal fluency, or verbal working memory task performance. Spatial working memory was slightly impaired. In conclusion, these results provide evidence for ketamine's differential impairment of verbal and spatial learning vs retrieval. By using the Morris water task, which is hippocampal-dependent, this study helps bridge the gap between nonhuman animal and human NMDAR antagonism research. Impaired cognition is a core feature of schizophrenia. A better understanding of NMDA antagonism, its physiological and cognitive consequences, may provide improved models of psychosis and cognitive therapeutics.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. [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.

  2. 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.

  3. 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

  4. 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.

  5. Adenosine A1 receptors (A1Rs) play a critical role in osteoclast formation and function

    PubMed Central

    Kara, Firas M.; Chitu, Violeta; Sloane, Jennifer; Axelrod, Matthew; Fredholm, Bertil B.; Stanley, E. Richard; Cronstein, Bruce N.

    2010-01-01

    Adenosine regulates a wide variety of physiological processes via interaction with one or more G-protein-coupled receptors (A1R, A2AR, A2BR, and A3R). Because A1R occupancy promotes fusion of human monocytes to form giant cells in vitro, we determined whether A1R occupancy similarly promotes osteoclast function and formation. Bone marrow cells (BMCs) were harvested from C57Bl/6 female mice or A1R-knockout mice and their wild-type (WT) littermates and differentiated into osteoclasts in the presence of colony stimulating factor-1 and receptor activator of NF-κB ligand in the presence or absence of the A1R antagonist 1,3-dipropyl-8-cyclopentyl xanthine (DPCPX). Osteoclast morphology was analyzed in tartrate-resistant acid phosphatase or F-actin-stained samples, and bone resorption was evaluated by toluidine blue staining of dentin. BMCs from A1R-knockout mice form fewer osteoclasts than BMCs from WT mice, and the A1R antagonist DPCPX inhibits osteoclast formation (IC50=1 nM), with altered morphology and reduced ability to resorb bone. A1R blockade increased ubiquitination and degradation of TRAF6 in RAW264.7 cells induced to differentiate into osteoclasts. These studies suggest a critical role for adenosine in bone homeostasis via interaction with adenosine A1R and further suggest that A1R may be a novel pharmacologic target to prevent the bone loss associated with inflammatory diseases and menopause.—Kara, F. M., Chitu, V., Sloane, J., Axelrod, M., Fredholm, B. B., Stanley, R., Cronstein, B. N. Adenosine A1 receptors (A1Rs) play a critical role in osteoclast formation and function. PMID:20181934

  6. 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.

  7. Renin-angiotensin system blockade alone or combined with ETA receptor blockade: effects on the course of chronic kidney disease in 5/6 nephrectomized Ren-2 transgenic hypertensive rats.

    PubMed

    Sedláková, Lenka; Čertíková Chábová, Věra; Doleželová, Šárka; Škaroupková, Petra; Kopkan, Libor; Husková, Zuzana; Červenková, Lenka; Kikerlová, Soňa; Vaněčková, Ivana; Sadowski, Janusz; Kompanowska-Jezierska, Elzbieta; Kujal, Petr; Kramer, Herbert J; Červenka, Luděk

    2017-01-01

    Early addition of endothelin (ET) type A (ET A ) receptor blockade to complex renin-angiotensin system (RAS) blockade has previously been shown to provide better renoprotection against progression of chronic kidney disease (CKD) in Ren-2 transgenic hypertensive rats (TGR) after 5/6 renal ablation (5/6 NX). In this study, we examined if additional protection is provided when ET A blockade is applied in rats with already developed CKD. For complex RAS inhibition, an angiotensin-converting enzyme inhibitor along with angiotensin II type 1 receptor blocker was used. Alternatively, ET A receptor blocker was added to the RAS blockade. The treatments were initiated 6 weeks after 5/6 NX and the follow-up period was 50 weeks. When applied in established CKD, addition of ET A receptor blockade to the complex RAS blockade brought no further improvement of the survival rate (30% in both groups); surprisingly, aggravated albuminuria (588 ± 47 vs. 245 ± 38 mg/24 h, p < 0.05) did not reduce renal glomerular injury index (1.25 ± 0.29 vs. 1.44 ± 0.26), did not prevent the decrease in creatinine clearance (203 ± 21 vs. 253 ± 17 µl/min/100 g body weight), and did not attenuate cardiac hypertrophy to a greater extent than observed in 5/6 NX TGR treated with complex RAS blockade alone. When applied in the advanced phase of CKD, addition of ET A receptor blockade to the complex RAS blockade brings no further beneficial renoprotective effects on the CKD progression in 5/6 NX TGR, in addition to those seen with RAS blockade alone.

  8. Blockade of NMDA receptors blocks the acquisition of cocaine conditioned approach in rats.

    PubMed

    Galaj, Ewa; Seepersad, Neal; Dakmak, Zena; Ranaldi, Robert

    2018-01-05

    Conditioned stimuli (CSs) exert motivational effects on both adaptive and pathological reward-related behaviors, including drug taking and seeking. We developed a paradigm that allows us to investigate the neuropharmacology by which previously neutral stimuli acquire the capacity to function as CSs and elicit (intravenous) cocaine conditioned approach and used this paradigm to test the role of NMDA receptor stimulation in the acquisition of cocaine conditioned approach. Rats were injected systemically with the NMDA receptor antagonist, MK-801, before the start of 4 consecutive conditioning sessions, each of which consisted of 20 randomly presented light/tone (CS) presentations paired with cocaine infusion contingent upon nose pokes. Rats later were subjected to a CS-only test. To test the role of NMDA receptor stimulation in the already established conditioned approach, rats were injected with MK-801 prior to the CS-only test that occurred after 18 CS-cocaine conditioning sessions. Blockade of NMDA receptors significantly impaired the acquisition of cocaine-conditioned approach as indicated by the emission of significantly fewer nose pokes and significantly longer latencies to nose poke during CS presentations. When MK-801 treatment was applied after the acquisition of conditioned approach responding it had no effect on these measures. These results suggest that NMDA receptor stimulation plays an important role in the acquisition of reward-related conditioned responses driven by intravenous cocaine-associated CSs. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Alpha1-adrenergic receptor blockade in the VTA modulates fear memories and stress responses.

    PubMed

    Solecki, Wojciech B; Szklarczyk, Klaudia; Klasa, Adam; Pradel, Kamil; Dobrzański, Grzegorz; Przewłocki, Ryszard

    2017-08-01

    Activity of the ventral tegmental area (VTA) and its terminals has been implicated in the Pavlovian associative learning of both stressful and rewarding stimuli. However, the role of the VTA noradrenergic signaling in fear responses remains unclear. We aimed to examine how alpha 1 -adrenergic receptor (α 1 -AR) signaling in the VTA affects conditioned fear. The role of α 1 -AR was assessed using the micro-infusions into the VTA of the selective antagonists (0.1-1µg/0.5µl prazosin and 1µg/0.5µl terazosin) in acquisition and expression of fear memory. In addition, we performed control experiments with α 1 -AR blockade in the mammillary bodies (MB) - a brain region with α 1 -AR expression adjacent to the VTA. Intra-VTA but not intra-MB α 1 -AR blockade prevented formation and retrieval of fear memories. Importantly, local administration of α 1 -AR antagonists did not influence footshock sensitivity, locomotion or anxiety-like behaviors. Similarly, α 1 -AR blockade in the VTA had no effects on negative affect measured as number of 22kHz ultrasonic vocalizations during fear conditioning training. We propose that noradrenergic signaling in the VTA via α 1 -AR regulates formation and retrieval of fear memories but not other behavioral responses to stressful environmental stimuli. It enhances the encoding of environmental stimuli by the VTA to form and retrieve conditioned fear memories and to predict future behavioral outcomes. Our results provide novel insight into the role of the VTA α 1 -AR signaling in the regulation of stress responsiveness and fear memory. Copyright © 2017 Elsevier B.V. and ECNP. All rights reserved.

  10. 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.

  11. 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.

  12. 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.

  13. 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)

  14. 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.

  15. Kinin B1 receptor blockade and ACE inhibition attenuate cardiac postinfarction remodeling and heart failure in rats

    SciTech Connect

    Lin, Xinchun

    Introduction: The aim of the present study was to evaluate the effects of the novel kinin B1 receptor antagonist BI113823 on postinfarction cardiac remodeling and heart failure, and to determine whether B1 receptor blockade alters the cardiovascular effects of an angiotensin 1 converting enzyme (ACE) inhibitor in rats. Methods and results: Sprague Dawley rats were subjected to permanent occlusion of the left coronary artery. Cardiovascular function was determined at 6 weeks postinfarction. Treatment with either B1 receptor antagonist (BI113823) or an ACE inhibitor (lisinopril) alone or in combination significantly reduced the heart weight-to-body weight and lung weight-to-body weight ratios, andmore » improved postinfarction cardiac function as evidenced by greater cardiac output, the maximum rate of left ventricular pressure rise (± dP/dtmax), left ventricle ejection fraction, fractional shorting, better wall motion, and attenuation of elevated left ventricular end diastolic pressure (LVEDP). Furthermore, all three treatment groups exhibited significant reduction in cardiac interstitial fibrosis, collagen deposition, CD68 positive macrophages, neutrophils, and proinflammatory cytokine production (TNF-α and IL-1β), compared to vehicle controls. Conclusion: The present study shows that treatment with the novel kinin B1 receptor antagonist, BI113823, reduces postinfarction cardiac remodeling and heart failure, and does not influence the cardiovascular effects of the ACE inhibitor. - Highlights: • We examined the role of kinin B1 receptors in the development of heart failure. • Kinin B1 receptor blockade attenuates post-infarction cardiac remodeling. • Kinin B1 receptor blockade improves dysfunction, and prevented heart failure. • B1 receptor blockade does not affect the cardio-protection of an ACE inhibitor.« less

  16. 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.

  17. Blockade of N-methyl-d-aspartate receptor activation suppresses learning-induced synaptic elimination

    PubMed Central

    Bock, Jörg; Braun, Katharina

    1999-01-01

    Auditory filial imprinting in the domestic chicken is accompanied by a dramatic loss of spine synapses in two higher associative forebrain areas, the mediorostral neostriatum/hyperstriatum ventrale (MNH) and the dorsocaudal neostriatum (Ndc). The cellular mechanisms that underlie this learning-induced synaptic reorganization are unclear. We found that local pharmacological blockade of N-methyl-d-aspartate (NMDA) receptors in the MNH, a manipulation that has been shown previously to impair auditory imprinting, suppresses the learning-induced spine reduction in this region. Chicks treated with the NMDA receptor antagonist 2-amino-5-phosphonovaleric acid (APV) during the behavioral training for imprinting (postnatal day 0–2) displayed similar spine frequencies at postnatal day 7 as naive control animals, which, in both groups, were significantly higher than in imprinted animals. Because the average dendritic length did not differ between the experimental groups, the reduced spine frequency can be interpreted as a reduction of the total number of spine synapses per neuron. In the Ndc, which is reciprocally connected with the MNH and not directly influenced by the injected drug, learning-induced spine elimination was partly suppressed. Spine frequencies of the APV-treated, behaviorally trained but nonimprinted animals were higher than in the imprinted animals but lower than in the naive animals. These results provide evidence that NMDA receptor activation is required for the learning-induced selective reduction of spine synapses, which may serve as a mechanism of information storage specific for juvenile emotional learning events. PMID:10051669

  18. 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.

  19. Endothelin ETA Receptor Blockade, by Activating ETB Receptors, Increases Vascular Permeability and Induces Exaggerated Fluid Retention.

    PubMed

    Vercauteren, Magali; Trensz, Frederic; Pasquali, Anne; Cattaneo, Christophe; Strasser, Daniel S; Hess, Patrick; Iglarz, Marc; Clozel, Martine

    2017-05-01

    Endothelin (ET) receptor antagonists have been associated with fluid retention. It has been suggested that, of the two endothelin receptor subtypes, ET B receptors should not be blocked, because of their involvement in natriuresis and diuresis. Surprisingly, clinical data suggest that ET A -selective antagonists pose a greater risk of fluid overload than dual antagonists. The purpose of this study was to evaluate the contribution of each endothelin receptor to fluid retention and vascular permeability in rats. Sitaxentan and ambrisentan as ET A -selective antagonists and bosentan and macitentan as dual antagonists were used as representatives of each class, respectively. ET A -selective antagonism caused a dose-dependent hematocrit/hemoglobin decrease that was prevented by ET B -selective receptor antagonism. ET A -selective antagonism led to a significant blood pressure reduction, plasma volume expansion, and a greater increase in vascular permeability than dual antagonism. Isolated vessel experiments showed that ET A -selective antagonism increased vascular permeability via ET B receptor overstimulation. Acutely, ET A -selective but not dual antagonism activated sympathetic activity and increased plasma arginine vasopressin and aldosterone concentrations. The hematocrit/hemoglobin decrease induced by ET A -selective antagonism was reduced in Brattleboro rats and in Wistar rats treated with an arginine vasopressin receptor antagonist. Finally, the decrease in hematocrit/hemoglobin was larger in the venous than in the arterial side, suggesting fluid redistribution. In conclusion, by activating ET B receptors, endothelin receptor antagonists (particularly ET A -selective antagonists) favor edema formation by causing: 1) fluid retention resulting from arginine vasopressin and aldosterone activation secondary to vasodilation, and 2) increased vascular permeability. Plasma volume redistribution may explain the clinical observation of a hematocrit/hemoglobin decrease

  20. Metabotropic glutamate receptors 5 blockade reverses spatial memory deficits in a mouse model of Parkinson's disease.

    PubMed

    De Leonibus, Elvira; Managò, Francesca; Giordani, Francesco; Petrosino, Francesco; Lopez, Sebastien; Oliverio, Alberto; Amalric, Marianne; Mele, Andrea

    2009-02-01

    Visuo-spatial deficits are the most consistently reported cognitive abnormalities in Parkinson's disease (PD), and they are frequently associated to motor symptoms in the early stages of the disease when dopamine loss is moderate and still restricted to the caudate-putamen. The metabotropic glutamate receptor 5 (mGluR5) antagonist, 2-methyl-6-(phenylethynyl)-pyridine (MPEP), has beneficial effects on motor symptoms in animal models of PD. However, the effects of MPEP on the cognitive deficits of the disease have never been investigated. Thus, the purpose of this study was to explore its therapeutic potentials by investigating its effects on the visuo-spatial deficits induced by 6-hydroxydopamine (6-OHDA) lesions of dorsal striatum in CD1 mice. The results demonstrated that systemic injections of MPEP (6, 12, and 24 mg/kg, i.p.) impair visuo-spatial discrimination in intact mice at high concentrations, whereas lower doses (1.5 and 3 mg/kg, i.p.) were void of effects. Nevertheless, when an ineffective dose (MPEP 3 mg/kg) was injected, either acutely or subchronically (8 days), it antagonized the visuo-spatial discrimination deficit induced by bilateral dopamine lesion of the striatum. Furthermore, the same treatment increased contralateral turning induced by L-DOPA in mice bearing unilateral 6-OHDA lesion. These results confirm the therapeutic potential of mGluR5 blockade on motor symptoms induced by reduced striatal dopamine function. Further, they demonstrate that mGluR5 blockade may also have beneficial effects on cognitive deficits induced by dopamine depletion.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Assessment of dopamine receptor blockade by neuroleptic drugs in the living human brain

    SciTech Connect

    Wong, D.F.; Wagner, H.N. Jr.; Coyle, J.

    1985-05-01

    Positron emission tomography (PET) makes it possible to attempt to relate directly the antipsychotic effect of neuroleptic drugs and their blocking effect on dopamine receptors (D2) in vivo. The authors have examined the ability of haloperidol (HAL) and molindone (MOL) to block the binding of C-11 n-methylspiperone (NMSP) in 6 normal subjects. A dose of 0.05 mg/kg of HAL resulted in a 68% drop in the slope of the caudate/cerebellum (Ca/Cb) vs. time. This slope is related to the rate of specific binding of NMSP to the receptor. A dose response was seen with both drugs. With increasing doses ofmore » HAL from .05 to 0.082 mg/kg, CA/Cb vs. time slope fell from .235 to .156/min. (N=4), progressively. Similarly with increasing doses of MOL of .16-.44 mg/kg slopes decreased from .0335 to .0155/min. (N=4). Similar degrees of post injection Ca/Cb ratio were produced with quantities of MOL and HAL administered in the oral dose ratio of doses 3-5:1 times greater than HAL. This is also the dose ratio at which we found similar dopamine receptor blockade by PET in vivo. A question that arises is why the in vitro affinity of HAL for D2 is 30 times greater than that of MOL in the human brain. The results raise the possibility that MOL metabolites are not only active in blocking D2 but indeed may possibly be more potent than MOL itself. It also helps confirm the site of action of MOL and its in vivo metabolites.« less

  7. Reversal of propranolol blockade of adrenergic receptors and related toxicity with drugs that increase cyclic AMP.

    PubMed

    Whitehurst, V E; Vick, J A; Alleva, F R; Zhang, J; Joseph, X; Balazs, T

    1999-09-01

    An overdose of propranolol, a widely used nonselective beta-adrenergic receptor blocking agent, can result in hypotension and bradycardia leading to irreversible shock and death. In addition, the blockade of adrenergic receptors can lead to alterations in neurotransmitter receptors resulting in the interruption of the activity of other second messengers and the ultimate cellular responses. In the present experiment, three agents, aminophylline, amrinone, and forskolin were tested in an attempt to reverse the potential lethal effects of a propranolol overdose in dogs. Twenty-two anesthetized beagle dogs were given a 10-min infusion of propranolol at a dose of 1 mg/kg/min. Six of the dogs, treated only with intravenous saline, served as controls. Within 15-30 min all six control dogs exhibited profound hypotension and severe bradycardia that led to cardiogenic shock and death. Seven dogs were treated with intravenous aminophylline 20 mg/kg 5 min after the end of the propranolol infusion. Within 10-15 min heart rate and systemic arterial blood pressure returned to near control levels, and all seven dogs survived. Intravenous amrinone (2-3 mg/kg) given to five dogs, and forskolin (1-2 mg/kg) given to four dogs, also increased heart rate and systemic arterial blood pressure but the recovery of these parameters was appreciably slower than that seen with aminophylline. All of these animals also survived with no apparent adverse effects. Histopathologic evaluation of the hearts of the dogs treated with aminophylline showed less damage (vacuolization, inflammation, hemorrhage) than the hearts from animals given propranolol alone. Results of this study showed that these three drugs, all of which increase cyclic AMP, are capable of reversing the otherwise lethal effects of a propranolol overdose in dogs.

  8. Blockade of vascular endothelial growth factor receptor and epidermal growth factor receptor signaling for therapy of metastatic human pancreatic cancer.

    PubMed

    Baker, Cheryl H; Solorzano, Carmen C; Fidler, Isaiah J

    2002-04-01

    We determined whether concurrent blockage of vascular endothelial growth factor (VEGF) receptor and epidermal growth factor (EGF) receptor signaling by two novel tyrosine kinase inhibitors, PTK 787 and PKI 166, respectively, can inhibit angiogenesis and, hence, the growth and metastasis of human pancreatic carcinoma in nude mice. Highly metastatic human pancreatic carcinoma L3.6pl cells were injected into the pancreas of nude mice. Seven days later, groups of mice began receiving oral doses of PTK 787 and PKI 166 three times weekly. Some groups of mice also received i.p. injections of gemcitabine twice a week. The mice were necropsied when the control mice became moribund. Treatment with PTK 787 and PKI 166, with gemcitabine alone, or with the combination of PTK 787, PKI 166, and gemcitabine produced 69, 50, and 97% reduction in the volume of pancreatic tumors, respectively. Administration of protein tyrosine kinase inhibitors and gemcitabine also significantly decreased the incidence of lymph node and liver metastasis. The therapeutic efficacy directly correlated with a decrease in circulating proangiogenic molecules (VEGF, interleukin-8), a decrease in microvessel density, a decrease in proliferating cell nuclear antigen staining, and an increase in apoptosis of tumor cells and endothelial cells. Therapies produced by combining gemcitabine with either PKI 166 or PTK 787 were similar to those produced by combining gemcitabine with both PKI 166 and PTK 787. These results suggest that blockade of either epidermal growth factor receptor or VEGF receptor signaling combined with chemotherapy provides an effective approach to the therapy of pancreatic cancer.

  9. C5a Receptor (CD88) Blockade Protects against MPO-ANCA GN

    PubMed Central

    Xiao, Hong; Dairaghi, Daniel J.; Powers, Jay P.; Ertl, Linda S.; Baumgart, Trageen; Wang, Yu; Seitz, Lisa C.; Penfold, Mark E.T.; Gan, Lin; Hu, Peiqi; Lu, Bao; Gerard, Norma P.; Gerard, Craig; Schall, Thomas J.; Jaen, Juan C.; Falk, Ronald J.

    2014-01-01

    Necrotizing and crescentic GN (NCGN) with a paucity of glomerular immunoglobulin deposits is associated with ANCA. The most common ANCA target antigens are myeloperoxidase (MPO) and proteinase 3. In a manner that requires activation of the alternative complement pathway, passive transfer of antibodies to mouse MPO (anti-MPO) induces a mouse model of ANCA NCGN that closely mimics human disease. Here, we confirm the importance of C5aR/CD88 in the mediation of anti-MPO–induced NCGN and report that C6 is not required. We further demonstrate that deficiency of C5a-like receptor (C5L2) has the reverse effect of C5aR/CD88 deficiency and results in more severe disease, indicating that C5aR/CD88 engagement enhances inflammation and C5L2 engagement suppresses inflammation. Oral administration of CCX168, a small molecule antagonist of human C5aR/CD88, ameliorated anti-MPO–induced NCGN in mice expressing human C5aR/CD88. These observations suggest that blockade of C5aR/CD88 might have therapeutic benefit in patients with ANCA-associated vasculitis and GN. PMID:24179165

  10. C5a receptor (CD88) blockade protects against MPO-ANCA GN.

    PubMed

    Xiao, Hong; Dairaghi, Daniel J; Powers, Jay P; Ertl, Linda S; Baumgart, Trageen; Wang, Yu; Seitz, Lisa C; Penfold, Mark E T; Gan, Lin; Hu, Peiqi; Lu, Bao; Gerard, Norma P; Gerard, Craig; Schall, Thomas J; Jaen, Juan C; Falk, Ronald J; Jennette, J Charles

    2014-02-01

    Necrotizing and crescentic GN (NCGN) with a paucity of glomerular immunoglobulin deposits is associated with ANCA. The most common ANCA target antigens are myeloperoxidase (MPO) and proteinase 3. In a manner that requires activation of the alternative complement pathway, passive transfer of antibodies to mouse MPO (anti-MPO) induces a mouse model of ANCA NCGN that closely mimics human disease. Here, we confirm the importance of C5aR/CD88 in the mediation of anti-MPO-induced NCGN and report that C6 is not required. We further demonstrate that deficiency of C5a-like receptor (C5L2) has the reverse effect of C5aR/CD88 deficiency and results in more severe disease, indicating that C5aR/CD88 engagement enhances inflammation and C5L2 engagement suppresses inflammation. Oral administration of CCX168, a small molecule antagonist of human C5aR/CD88, ameliorated anti-MPO-induced NCGN in mice expressing human C5aR/CD88. These observations suggest that blockade of C5aR/CD88 might have therapeutic benefit in patients with ANCA-associated vasculitis and GN.

  11. PCA3 Silencing Sensitizes Prostate Cancer Cells to Enzalutamide-mediated Androgen Receptor Blockade.

    PubMed

    Özgür, Emre; Celik, Ayca Iribas; Darendeliler, Emin; Gezer, Ugur

    2017-07-01

    Prostate cancer (PCa) is an androgen-dependent disease. Novel anti-androgens (i.e. enzalutamide) have recently been developed for the treatment of patients with metastatic castration-resistant prostate cancer (CRPC). Evidence is accumulating that prostate cancer antigen 3 (PCA3) is involved in androgen receptor (AR) signaling. Here, in combination with enzalutamide-mediated AR blockade, we investigated the effect of PCA3 targeting on the viability of PCa cells. In hormone-sensitive LNCaP cells, AR-overexpressing LNCaP-AR + cells and VCaP cells (representing CRPC), PCA3 was silenced using siRNA oligonucleotides. Gene expression and cell viability was assessed in PCA3-silenced and/or AR-blocked cells. PCA3 targeting reduced the expression of AR-related genes (i.e. prostate-specific antigen (PSA) and prostate-specific transcript 1 (non-protein coding) (PCGEM1)) and potentiated the effect of enzalutamide. Proliferation of PCa cells was suppressed upon PCA3 silencing with a greater effect in LNCaP-AR + cells. Furthermore, PCA3 silencing sensitized PCa cells to enzalutamide-induced loss of cell growth. PCA3, as a therapeutic target in PCa, might be used to potentiate AR antagonists. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  12. TAM receptor tyrosine kinases as emerging targets of innate immune checkpoint blockade for cancer therapy.

    PubMed

    Akalu, Yemsratch T; Rothlin, Carla V; Ghosh, Sourav

    2017-03-01

    Cancer immunotherapy utilizing T-cell checkpoint inhibitors has shown tremendous clinical success. Yet, this mode of treatment is effective in only a subset of patients. Unresponsive patients tend to have non-T-cell-inflamed tumors that lack markers associated with the activation of adaptive anti-tumor immune responses. Notably, elimination of cancer cells by T cells is critically dependent on the optimal activity of innate immune cells. Therefore, identifying new targets that regulate innate immune cell function and promote the engagement of adaptive tumoricidal responses is likely to lead to the development of improved therapies against cancer. Here, we review the TAM receptor tyrosine kinases-TYRO3, AXL, and MERTK-as an emerging class of innate immune checkpoints that participate in key steps of anti-tumoral immunity. Namely, TAM-mediated efferocytosis, negative regulation of dendritic cell activity, and dysregulated production of chemokines collectively favor the escape of malignant cells. Hence, disabling TAM signaling may promote engagement of adaptive immunity and complement T-cell checkpoint blockade. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Cardiovascular effects of vasopressin following V(1) receptor blockade compared to effects of nitroglycerin.

    PubMed

    Cooke, C R; Wall, B M; Huch, K M; Mangold, T

    2001-09-01

    Studies to more clearly determine the mechanisms associated with arginine vasopressin (AVP)-induced vasodilation were performed in normal subjects and in quadriplegic subjects with impaired efferent sympathetic responses. Studies to compare the effects of AVP with the hemodynamic effects of nitroglycerin, an agent that primarily affects venous capacitance vessels, were also performed in normal subjects. Incremental infusions of AVP following V(1)-receptor blockade resulted in equivalent reductions in systemic vascular resistance (SVRI) in normal and in quadriplegic subjects. However, there were major differences in the effect on mean arterial pressure (MAP), which was reduced in quadriplegic subjects but did not change in normal subjects. This difference in MAP can be attributed to a difference in the magnitude of increase in cardiac output (CI), which was twofold greater in normal than in quadriplegic subjects. These observations are consistent with AVP-induced vasodilation of arterial resistance vessels with reflex sympathetic enhancement of CI and are clearly different from the hemodynamic effects of nitroglycerin, i.e., reductions in MAP, CI, and indexes of cardiac preload, with only minor changes in SVRI.

  14. N-Methyl-d-Aspartate (NMDA) Receptor Blockade Prevents Neuronal Death Induced by Zika Virus Infection.

    PubMed

    Costa, Vivian V; Del Sarto, Juliana L; Rocha, Rebeca F; Silva, Flavia R; Doria, Juliana G; Olmo, Isabella G; Marques, Rafael E; Queiroz-Junior, Celso M; Foureaux, Giselle; Araújo, Julia Maria S; Cramer, Allysson; Real, Ana Luíza C V; Ribeiro, Lucas S; Sardi, Silvia I; Ferreira, Anderson J; Machado, Fabiana S; de Oliveira, Antônio C; Teixeira, Antônio L; Nakaya, Helder I; Souza, Danielle G; Ribeiro, Fabiola M; Teixeira, Mauro M

    2017-04-25

    Zika virus (ZIKV) infection is a global health emergency that causes significant neurodegeneration. Neurodegenerative processes may be exacerbated by N -methyl-d-aspartate receptor (NMDAR)-dependent neuronal excitoxicity. Here, we have exploited the hypothesis that ZIKV-induced neurodegeneration can be rescued by blocking NMDA overstimulation with memantine. Our results show that ZIKV actively replicates in primary neurons and that virus replication is directly associated with massive neuronal cell death. Interestingly, treatment with memantine or other NMDAR blockers, including dizocilpine (MK-801), agmatine sulfate, or ifenprodil, prevents neuronal death without interfering with the ability of ZIKV to replicate in these cells. Moreover, in vivo experiments demonstrate that therapeutic memantine treatment prevents the increase of intraocular pressure (IOP) induced by infection and massively reduces neurodegeneration and microgliosis in the brain of infected mice. Our results indicate that the blockade of NMDARs by memantine provides potent neuroprotective effects against ZIKV-induced neuronal damage, suggesting it could be a viable treatment for patients at risk for ZIKV infection-induced neurodegeneration. IMPORTANCE Zika virus (ZIKV) infection is a global health emergency associated with serious neurological complications, including microcephaly and Guillain-Barré syndrome. Infection of experimental animals with ZIKV causes significant neuronal damage and microgliosis. Treatment with drugs that block NMDARs prevented neuronal damage both in vitro and in vivo These results suggest that overactivation of NMDARs contributes significantly to the neuronal damage induced by ZIKV infection, and this is amenable to inhibition by drug treatment. Copyright © 2017 Costa et al.

  15. N-Methyl-d-Aspartate (NMDA) Receptor Blockade Prevents Neuronal Death Induced by Zika Virus Infection

    PubMed Central

    Costa, Vivian V.; Del Sarto, Juliana L.; Rocha, Rebeca F.; Silva, Flavia R.; Doria, Juliana G.; Olmo, Isabella G.; Marques, Rafael E.; Queiroz-Junior, Celso M.; Foureaux, Giselle; Araújo, Julia Maria S.; Cramer, Allysson; Real, Ana Luíza C. V.; Ribeiro, Lucas S.; Sardi, Silvia I.; Ferreira, Anderson J.; Machado, Fabiana S.; de Oliveira, Antônio C.; Teixeira, Antônio L.; Nakaya, Helder I.; Souza, Danielle G.

    2017-01-01

    ABSTRACT Zika virus (ZIKV) infection is a global health emergency that causes significant neurodegeneration. Neurodegenerative processes may be exacerbated by N-methyl-d-aspartate receptor (NMDAR)-dependent neuronal excitoxicity. Here, we have exploited the hypothesis that ZIKV-induced neurodegeneration can be rescued by blocking NMDA overstimulation with memantine. Our results show that ZIKV actively replicates in primary neurons and that virus replication is directly associated with massive neuronal cell death. Interestingly, treatment with memantine or other NMDAR blockers, including dizocilpine (MK-801), agmatine sulfate, or ifenprodil, prevents neuronal death without interfering with the ability of ZIKV to replicate in these cells. Moreover, in vivo experiments demonstrate that therapeutic memantine treatment prevents the increase of intraocular pressure (IOP) induced by infection and massively reduces neurodegeneration and microgliosis in the brain of infected mice. Our results indicate that the blockade of NMDARs by memantine provides potent neuroprotective effects against ZIKV-induced neuronal damage, suggesting it could be a viable treatment for patients at risk for ZIKV infection-induced neurodegeneration. PMID:28442607

  16. Mineralocorticoid receptor blockade but not steroid withdrawal reverses renal fibrosis in deoxycorticosterone/salt rats.

    PubMed

    Lam, Emily Y M; Funder, John W; Nikolic-Paterson, David J; Fuller, Peter J; Young, Morag J

    2006-07-01

    The pathophysiologic effects of nonepithelial mineralocorticoid receptor (MR) activation include vascular inflammation followed by renal and cardiac remodeling in experimental animals. We have recently shown that MR blockade can reverse established cardiac fibrosis and vascular inflammation; the present study explores whether a similar protection is seen in renal tissue. Rats were uninephrectomized and maintained on 0.9% NaCl solution to drink and treated as follows: control, vehicle; deoxycorticosterone (DOC), 20 mg/wk sc for 4 wk and then killed; DOC for 8 wk; DOC for 4 wk and no steroid for wk 5-8; DOC for 8 wk and eplerenone 100 mg/kg.d in the food for wk 5-8. DOC increased renal collagen at 4 and 8 wk; rats given DOC for 4 wk and killed at 8 wk showed levels of fibrosis identical with those killed at 4 wk, whereas rats given DOC for 8 wk plus eplerenone for wk 5-8 were indistinguishable from control. The inflammatory markers ED-1, osteopontin, and cyclooxygenase-2 remained significantly elevated despite the withdrawal of DOC (DOC404), whereas eplerenone restored cyclooxygenase-2 expression (but not that of ED-1 or osteopontin) to control levels. In addition, markers of oxidative stress and TGFbeta were determined. We hypothesize that continuing tubular inflammation and fibrosis despite DOC withdrawal indicates that the renal tissue may reflect MR activation in the context of tissue damage.

  17. Synaptic potentials in respiratory neurones during evoked phase switching after NMDA receptor blockade in the cat

    PubMed Central

    Pierrefiche, O; Haji, A; Foutz, A S; Takeda, R; Champagnat, J; Denavit-Saubié, M

    1998-01-01

    Blockade of NMDA receptors by dizocilpine impairs the inspiratory off-switch (IOS) of central origin but not the IOS evoked by stimulation of sensory afferents. To investigate whether this difference was due to the effects of different patterns of synaptic interactions on respiratory neurones, we stimulated electrically the superior laryngeal nerve (SLN) or vagus nerve in decerebrate cats before and after i.v. administration of dizocilpine, whilst recording intracellularly. Phrenic nerve responses to ipsilateral SLN or vagal stimulation were: at mid-inspiration, a transient inhibition often followed by a brief burst of activity; at late inspiration, an IOS; and at mid-expiration, a late burst of activity. In all neurones (n = 16), SLN stimulation at mid-inspiration evoked an early EPSP during phase 1 (latency to the arrest of phrenic nerve activity), followed by an IPSP in inspiratory (I) neurones (n = 8) and by a wave of EPSPs in post-inspiratory (PI) neurones (n = 8) during phase 2 (inhibition of phrenic activity). An EPSP in I neurones and an IPSP in PI neurones occurred during phase 3 (brief phrenic burst) following phase 2. Evoked IOS was associated with a fast (phase 1) activation of PI neurones, whereas during spontaneous IOS, a progressive (30-50 ms) depolarization of PI neurones preceded the arrest of phrenic activity. Phase 3 PSPs were similar to those occurring during the burst of activity seen at the start of spontaneous inspiration. Dizocilpine did not suppress the evoked phrenic inhibition and the late burst of activity. The shapes and timing of the evoked PSPs and the changes in membrane potential in I and PI neurones during the phase transition were not altered. We hypothesize that afferent sensory pathways not requiring NMDA receptors (1) terminate inspiration through a premature activation of PI neurones, and (2) evoke a late burst of phrenic activity which might be the first stage of the inspiratory on-switch. PMID:9508816

  18. Endocannabinoid receptor blockade reduces alanine aminotransferase in polycystic ovary syndrome independent of weight loss.

    PubMed

    Dawson, Alison J; Kilpatrick, Eric S; Coady, Anne-Marie; Elshewehy, Abeer M M; Dakroury, Youssra; Ahmed, Lina; Atkin, Stephen L; Sathyapalan, Thozhukat

    2017-07-14

    Evidence suggests that endocannabinoid system activation through the cannabinoid receptor 1 (CB1) is associated with enhanced liver injury, and CB1 antagonism may be beneficial. The aim of this study was to determine the impact of rimonabant (CB1 antagonist) on alanine aminotransferase (ALT), a hepatocellular injury marker, and a hepatic inflammatory cytokine profile. Post hoc review of 2 studies involving 50 obese women with PCOS and well matched for weight, randomised to weight reducing therapy; rimonabant (20 mg od) or orlistat (120 mg tds), or to insulin sensitising therapy metformin, (500 mg tds), or pioglitazone (45 mg od). No subject had non-alcoholic fatty liver disease (NAFLD). Treatment with rimonabant for 12 weeks reduced both ALT and weight (p < 0.01), and there was a negative correlation between Δ ALT and Δ HOMA-IR (p < 0.001), but not between Δ ALT and Δ weight. There was a significant reduction of weight with orlistat (p < 0.01); however, orlistat, metformin and pioglitazone had no effect on ALT. The free androgen index fell in all groups (p < 0.05). The inflammatory marker hs-CRP was reduced by pioglitazone (p < 0.001) alone and did not correlate with changes in ALT. The inflammatory cytokine profile for IL-1β, IL-6, IL-7, IL-10, IL12, TNF-α, MCP-1 and INF-γ did not differ between groups. None of the interventions had an effect on biological variability of ALT. Rimonabant through CB1 receptor blockade decreased serum ALT that was independent of weight loss and hepatic inflammatory markers in obese women with PCOS without NAFLD. ISRCTN58369615 (February 2007; retrospectively registered) ISRCTN75758249 (October 2007; retrospectively registered).

  19. Testosterone receptor blockade after trauma-hemorrhage improves cardiac and hepatic functions in males.

    PubMed

    Remmers, D E; Wang, P; Cioffi, W G; Bland, K I; Chaudry, I H

    1997-12-01

    Although studies have shown that testosterone receptor blockade with flutamide after hemorrhage restores the depressed immune function, it remains unknown whether administration of flutamide following trauma and hemorrhage and resuscitation has any salutary effects on the depressed cardiovascular and hepatocellular functions. To study this, male rats underwent a laparotomy (representing trauma) and were then bled and maintained at a mean arterial pressure (MAP) of 40 mmHg until the animals could not maintain this pressure. Ringer lactate was given to maintain a MAP of 40 mmHg until 40% of the maximal shed blood volume was returned in the form of Ringer lactate. The rats were then resuscitated with four times the shed blood volume in the form of Ringer lactate over 60 min. Flutamide (25 mg/kg) or an equal volume of the vehicle propanediol was injected subcutaneously 15 min before the end of resuscitation. Various in vivo heart performance parameters (e.g., maximal rate of the pressure increase or decrease), cardiac output, and hepatocellular function (i.e., the maximum velocity and the overall efficiency of indocyanine green clearance) were determined at 20 h after resuscitation. Additionally, hepatic microvascular blood flow (HMBF) was determined using a laser Doppler flowmeter. The results indicate that left ventricular performance, cardiac output, HMBF, and hepatocellular function decreased significantly at 20 h after the completion of trauma, hemorrhage, and resuscitation. Administration of the testosterone receptor blocker flutamide, however, significantly improved cardiac performance, HMBF, and hepatocellular function. Thus flutamide appears to be a novel and useful adjunct for improving cardiovascular and hepatocellular functions in males following trauma and hemorrhagic shock.

  20. Blockade of Central GLP-1 Receptors Deteriorates the Improvement of Diabetes after Ileal Transposition.

    PubMed

    Chen, Weijie; Xu, Qianqian; Xiao, Yiding; Zhou, Jiaolin; Zhang, Weimin; Lin, Guole; Gong, Fengying

    2016-01-01

    Background: The mechanism of improvement of type 2 diabetes mellitus induced by ileal transposition (IT) is undefined. Our aim was to investigate the possible role of central glucagon-like peptide 1 (GLP-1) after IT. Methods: Ninety male diabetic rats were randomly divided into the IT, sham IT (S-IT) and control group. The food intake, glucose metabolism and GLP-1 level were measured. Subsequently, we administered GLP-1 antagonist via lateral brain ventricle cannula to block central GLP-1 receptor, and verified whether the food intake, glucose metabolism changed. And the activated pro-opiomelanocortin (POMC) neurons in different groups were compared after sacrifice. Results: IT induced significant diabetic improvement with decreased maximum food intake and higher postprandial GLP-1 level. The GLP-1 level in cerebrospinal fluid increased in correlation with the plasma GLP-1 level. When the central GLP-1 receptor antagonist was given to the IT group rats, the improvement of the glucose level declined. The glucose level surged (169.9 ± 14.2) % during the oral glucose tolerance test, the range was larger than that before central blockade ((67.1 ± 14.2) %, P < 0.001). Moreover, the POMC neuron number in the arcuate nucleus of the hypothalamus were reduced (12.7 ± 6.1 at a magnification of 100×). The relative content level of POMC-derived peptides in the pituitary was lower (0.1 ± 0.05). Conclusions: The central GLP-1 might play an important role in the remission of diabetes after IT. POMC neurons in the hypothalamus may be activated by the enhanced level of GLP-1 after IT.

  1. 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.

  2. Blockade of Cocaine or σ Receptor Agonist Self Administration by Subtype-Selective σ Receptor Antagonists.

    PubMed

    Katz, Jonathan L; Hiranita, Takato; Kopajtic, Theresa A; Rice, Kenner C; Mesangeau, Christophe; Narayanan, Sanju; Abdelazeem, Ahmed H; McCurdy, Christopher R

    2016-07-01

    The identification of sigma receptor (σR) subtypes has been based on radioligand binding and, despite progress with σ1R cellular function, less is known about σR subtype functions in vivo. Recent findings that cocaine self administration experience will trigger σR agonist self administration was used in this study to assess the in vivo receptor subtype specificity of the agonists (+)-pentazocine, PRE-084 [2-(4-morpholinethyl) 1-phenylcyclohexanecarboxylate hydrochloride], and 1,3-di-o-tolylguanidine (DTG) and several novel putative σR antagonists. Radioligand binding studies determined in vitro σR selectivity of the novel compounds, which were subsequently studied for self administration and antagonism of cocaine, (+)-pentazocine, PRE-084, or DTG self administration. Across the dose ranges studied, none of the novel compounds were self administered, nor did they alter cocaine self administration. All compounds blocked DTG self administration, with a subset also blocking (+)-pentazocine and PRE-084 self administration. The most selective of the compounds in binding σ1Rs blocked cocaine self administration when combined with a dopamine transport inhibitor, either methylphenidate or nomifensine. These drug combinations did not decrease rates of responding maintained by food reinforcement. In contrast, the most selective of the compounds in binding σ2Rs had no effect on cocaine self administration in combination with either dopamine transport inhibitor. Thus, these results identify subtype-specific in vivo antagonists, and the utility of σR agonist substitution for cocaine self administration as an assay capable of distinguishing σR subtype selectivity in vivo. These results further suggest that effectiveness of dual σR antagonism and dopamine transport inhibition in blocking cocaine self administration is specific for σ1Rs and further support this dual targeting approach to development of cocaine antagonists. U.S. Government work not protected by U

  3. Blockade of Cocaine or σ Receptor Agonist Self Administration by Subtype-Selective σ Receptor Antagonists

    PubMed Central

    Hiranita, Takato; Kopajtic, Theresa A.; Rice, Kenner C.; Mesangeau, Christophe; Narayanan, Sanju; Abdelazeem, Ahmed H.; McCurdy, Christopher R.

    2016-01-01

    The identification of sigma receptor (σR) subtypes has been based on radioligand binding and, despite progress with σ1R cellular function, less is known about σR subtype functions in vivo. Recent findings that cocaine self administration experience will trigger σR agonist self administration was used in this study to assess the in vivo receptor subtype specificity of the agonists (+)-pentazocine, PRE-084 [2-(4-morpholinethyl) 1-phenylcyclohexanecarboxylate hydrochloride], and 1,3-di-o-tolylguanidine (DTG) and several novel putative σR antagonists. Radioligand binding studies determined in vitro σR selectivity of the novel compounds, which were subsequently studied for self administration and antagonism of cocaine, (+)-pentazocine, PRE-084, or DTG self administration. Across the dose ranges studied, none of the novel compounds were self administered, nor did they alter cocaine self administration. All compounds blocked DTG self administration, with a subset also blocking (+)-pentazocine and PRE-084 self administration. The most selective of the compounds in binding σ1Rs blocked cocaine self administration when combined with a dopamine transport inhibitor, either methylphenidate or nomifensine. These drug combinations did not decrease rates of responding maintained by food reinforcement. In contrast, the most selective of the compounds in binding σ2Rs had no effect on cocaine self administration in combination with either dopamine transport inhibitor. Thus, these results identify subtype-specific in vivo antagonists, and the utility of σR agonist substitution for cocaine self administration as an assay capable of distinguishing σR subtype selectivity in vivo. These results further suggest that effectiveness of dual σR antagonism and dopamine transport inhibition in blocking cocaine self administration is specific for σ1Rs and further support this dual targeting approach to development of cocaine antagonists. PMID:27189970

  4. [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.

  5. 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.

  6. 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.

  7. Caspase blockade induces RIP3-mediated programmed necrosis in Toll-like receptor-activated microglia.

    PubMed

    Kim, S J; Li, Jianrong

    2013-07-11

    Microglia are the resident immune cells in the central nervous system and key players against pathogens and injury. However, persistent microglial activation often exacerbates pathological damage and has been implicated in many neurological diseases. Despite their pivotal physiological and pathophysiological roles, how the survival and death of activated microglia is regulated remains poorly understood. We report here that microglia activated through Toll-like receptors (TLRs) undergo RIP1/RIP3-dependent programmed necrosis (necroptosis) when exposed to the pan caspase inhibitor zVAD-fmk. Although zVAD-fmk and the caspase-8 inhibitor IETD-fmk had no effect on unstimulated primary microglia, they markedly sensitized microglia to TLR1/2,3,4,7/8 ligands or TNF treatment, triggering programmed necrosis that was completely blocked by R1P1 kinase inhibitor necrostatin-1. Interestingly, necroptosis induced by TLR ligands and zVAD was restricted to microglial cells and was not observed in astrocytes, neurons or oligodendrocytes even though they are known to express certain TLRs. Deletion of genes encoding TNF or TNFR1 failed to prevent lipopolysaccharide- and poly(I:C)-induced microglial necroptosis, unveiling a TNF-independent programmed necrosis pathway in TLR3- and TLR4-activated microglia. Microglia from mice lacking functional TRIF were fully protected against TLR3/4 activation and zVAD-fmk-induced necrosis, and genetic deletion of rip3 also prevented microglia necroptosis. Activation of c-jun N-terminal kinase and generation of specific reactive oxygen species were downstream signaling events required for microglial cell death execution. Taken together, this study reveals a robust RIP3-dependent necroptosis signaling pathway in TLR-activated microglia upon caspase blockade and suggests that TLR signaling and programmed cell death pathways are closely linked in microglia, which could contribute to neuropathology and neuroinflammation when dysregulated.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Blockade of lysophosphatidic acid receptors LPAR1/3 ameliorates lung fibrosis induced by irradiation

    SciTech Connect

    Gan, Lu; Xue, Jian-Xin; Laboratory of Stem Cell Biology, West China Hospital, Sichuan University, Chengdu

    2011-05-27

    Highlights: {yields} Lysophosphatidic acid (LPA) levels and its receptors LPAR1/3 transcripts were elevated during the development of radiation-induced lung fibrosis. {yields} Lung fibrosis was obviously alleviated in mice treated with the dual LPAR1/3 antagonist, VPC12249. {yields} VPC12249 administration effectively inhibited radiation-induced fibroblast accumulation in vivo, and suppressed LPA-induced fibroblast proliferation in vitro. {yields} LPA-LPAR1/3 signaling regulated TGF{beta}1 and CTGF expressions in radiation-challenged lungs, but only influenced CTGF expression in cultured fibroblasts. {yields} LPA-LPAR1/3 signaling induced fibroblast proliferation through a CTGF-dependent pathway, rather than through TGF{beta}1 activation. -- Abstract: Lung fibrosis is a common and serious complication of radiation therapy formore » lung cancer, for which there are no efficient treatments. Emerging evidence indicates that lysophosphatidic acid (LPA) and its receptors (LPARs) are involved in the pathogenesis of fibrosis. Here, we reported that thoracic radiation with 16 Gy in mice induced development of radiation lung fibrosis (RLF) accompanied by obvious increases in LPA release and LPAR1 and LPAR3 (LPAR1/3) transcripts. RLF was significantly alleviated in mice treated with the dual LPAR1/3 antagonist, VPC12249. VPC12249 administration effectively prolonged animal survival, restored lung structure, inhibited fibroblast accumulation and reduced collagen deposition. Moreover, profibrotic cytokines in radiation-challenged lungs obviously decreased following administration of VPC12249, including transforming growth factor {beta}1 (TGF{beta}1) and connective tissue growth factor (CTGF). In vitro, LPA induced both fibroblast proliferation and CTGF expression in a dose-dependent manner, and both were suppressed by blockade of LPAR1/3. The pro-proliferative activity of LPA on fibroblasts was inhibited by siRNA directed against CTGF. Together, our data suggest that the LPA

  14. Blockade of mesolimbic dopamine D3 receptors inhibits stress-induced reinstatement of cocaine-seeking in rats

    PubMed Central

    Gilbert, Jeremy; Campos, Arlene C.; Kline, Nicole; Ashby, Charles R.; Hagan, Jim J.; Heidbreder, Christian A.; Gardner, Eliot L.

    2013-01-01

    Rationale The dopamine (DA) D3 receptor is preferentially expressed in the mesolimbic system. We have previously shown that selective D3 receptor blockade by the novel D3 antagonist SB-277011A inhibits cocaine’s reinforcing action and cocaine-induced reinstatement of cocaine-seeking behavior. Objective In the present study, we investigated whether SB-277011A similarly inhibits stress-induced reinstatement of cocaine-seeking behavior. Methods Rats were allowed to self-administer cocaine (0.5 mg/kg per infusion, 3 h per session) for 10–14 days, followed by a once-daily extinction session for 7–14 days during which saline was substituted for cocaine. Extinction criteria were fewer than ten lever-presses per 3-h session for at least 3 consecutive days. After cocaine-seeking behavior was extinguished, each animal was tested twice for footshock-stress-induced reinstatement, once with vehicle (25% hydroxypropyl-β-cyclodextrin) and once with one of three doses of SB-277011A in counterbalanced fashion. Results During the last 3 days of cocaine self-administration (SA), active lever-presses were approximately 100 per session under fixed-ratio 2 reinforcement (~25 mg/kg cocaine per session). After extinction, intermittent footshock (10 min, 0.5 mA, 0.5 s on with a mean inter-shock interval of 40 s) robustly reinstated the cocaine-seeking behavior (8.4±3.6 active lever-presses in last extinction session to 35.3±5.2 in animals after footshock stress). Intraperitoneal (IP) injections of SB-277011A (3, 6, and 12 mg/kg) dose-dependently blocked stress-induced reinstatement of cocaine-seeking. Reinstatement was also blocked by microinjections of SB-277011A (1.5 μg/0.5 μl per side) bilaterally into the nucleus accumbens, but not into the dorsal striatum. Conclusions The mesolimic DA D3 receptor plays an important role in mediating stress-induced reinstatement. PMID:15083257

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. NEUROTROPHIN RECEPTOR BLOCKADE ATTENUATES DIESEL EXHAUST PARTICULATE MATTER (DEP) ENHANCEMENT OF ALLERGIC RESPONSES

    EPA Science Inventory

    ABSTRACT BODY:
    Recent investigations have linked neurotrophins including NGF, NT-3, and BDNF to allergic airways diseases. Antibody blockade of NGF attenuates airway resistance associated with allergic airway responses in mice. Mice administered an antibody against the low aff...

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Effects of a Proprietary Standardized Orthosiphon stamineus Ethanolic Leaf Extract on Enhancing Memory in Sprague Dawley Rats Possibly via Blockade of Adenosine A2A Receptors

    PubMed Central

    Choudhary, Yogendra; Choudhary, Vandana Kotak; Bommu, Praveen; Wong, Hoi Jin

    2015-01-01

    The aim of the study was to explore a propriety standardized ethanolic extract from leaves of Orthosiphon stamineus Benth in improving impairments in short-term social memory in vivo, possibly via blockade of adenosine A2A receptors (A2AR). The ethanolic extract of O. stamineus leaves showed significant in vitro binding activity of A2AR with 74% inhibition at 150 μg/ml and significant A2AR antagonist activity with 98% inhibition at 300 μg/mL. A significant adenosine A1 receptor (A1R) antagonist activity with 100% inhibition was observed at 300 μg/mL. Its effect on learning and memory was assessed via social recognition task using Sprague Dawley rats whereby the ethanolic extract of O. stamineus showed significant (p < 0.001) change in recognition index (RI) at 300 mg/kg and 600 mg/kg p.o and 120 mg/kg i.p., respectively, compared to the vehicle control. In comparison, the ethanolic extract of Polygonum minus aerial parts showed small change in inflexion; however, it remained insignificant in RI at 200 mg/kg p.o. Our findings suggest that the ethanolic extract of O. stamineus leaves improves memory by reversing age-related deficits in short-term social memory and the possible involvement of adenosine A1 and adenosine A2A as a target bioactivity site in the restoration of memory. PMID:26649059

  6. Role of adiponectin in the metabolic effects of cannabinoid type 1 receptor blockade in mice with diet-induced obesity

    PubMed Central

    Godlewski, Grzegorz; Earley, Brian J.; Zhou, Liang; Jourdan, Tony; Szanda, Gergö; Cinar, Resat; Kunos, George

    2013-01-01

    The adipocyte-derived hormone adiponectin promotes fatty acid oxidation and improves insulin sensitivity and thus plays a key role in the regulation of lipid and glucose metabolism and energy homeostasis. Chronic cannabinoid type 1 (CB1) receptor blockade also increases lipid oxidation and improves insulin sensitivity in obese individuals or animals, resulting in reduced cardiometabolic risk. Chronic CB1 blockade reverses the obesity-related decline in serum adiponectin levels, which has been proposed to account for the metabolic effects of CB1 antagonists. Here, we investigated the metabolic actions of the CB1 inverse agonist rimonabant in high-fat diet (HFD)-induced obese adiponectin knockout (Adipo−/−) mice and their wild-type littermate controls (Adipo+/+). HFD-induced obesity and its hormonal/metabolic consequences were indistinguishable in the two strains. Daily treatment of obese mice with rimonabant for 7 days resulted in significant and comparable reductions in body weight, serum leptin, free fatty acid, cholesterol, and triglyceride levels in the two strains. Rimonabant treatment improved glucose homeostasis and insulin sensitivity to the same extent in Adipo+/+ and Adipo−/− mice, whereas it reversed the HFD-induced hepatic steatosis, fibrosis, and hepatocellular damage only in the former. The adiponectin-dependent, antisteatotic effect of rimonabant was mediated by reduced uptake and increased β-oxidation of fatty acids in the liver. We conclude that reversal of the HFD-induced hepatic steatosis and fibrosis by chronic CB1 blockade, but not the parallel reduction in adiposity and improved glycemic control, is mediated by adiponectin. PMID:24381003

  7. 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.

  8. 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.

  9. Adenosine A(2A) receptor antagonists are broad facilitators of antinicotinic neuromuscular blockade monitored either with 2 Hz train-of-four or 50 Hz tetanic stimuli.

    PubMed

    Pereira, Monalisa W; Correia-de-Sá, Paulo; Alves-Do-Prado, Wilson

    2012-10-01

    1. The 2 Hz train-of-four ratio (TOF(ratio)) is used to monitor the degree of patient curarization. Using a rat phrenic nerve-hemidiaphragm preparation, we showed that antinicotinic agents, such as hexamethonium, d-tubocurarine and pancuronium, but not cisatracurium, decreased contractions produced by physiological nerve activity patterns (50 Hz) more efficiently than those caused by 2 Hz trains. Uncertainty about the usefulness of the TOF(ratio) to control safe recovery from curarization prompted us to investigate the muscarinic and adenosine neuromodulation of tetanic (50 Hz) fade induced by antinicotinic agents at concentrations that cause a 25% reduction in the TOF(ratio) (TOF(fade)). 2. Tetanic fade caused by d-tubocurarine (1.1 μmol/L), pancuronium (3 μmol/L) and hexamethonium (5.47 mmol/L) was attenuated by blocking presynaptic inhibitory muscarinic M(2) and adenosine A(1) receptors with methoctramine (1 μmol/L) and 1,3-dipropyl-8-cyclopentylxanthine (2.5 nmol/L), respectively. These compounds enhanced rather than decreased tetanic fade induced by cisatracurium (2.2 μmol/L), but they consistently attenuated cisatracurium-induced TOF(fade). The effect of the M(1) receptor antagonist pirenzepine (10 nmol/L) on fade produced by antinicotinic agents at 50 Hz was opposite to that observed with TOF stimulation. Blockade of adenosine A(2A) receptors with ZM 241385 (10 nmol/L) attenuated TOF(fade) caused by all antinicotinic drugs tested, with the exception of the 'pure' presynaptic nicotinic antagonist hexamethonium. ZM 241385 was the only compound tested in this series that facilitated recovery from tetanic fade produced by cisatracurium. 3. The data suggest that distinct antinicotinic relaxants interfere with fine-tuning neuromuscular adaptations to motor nerve stimulation patterns via activation of presynaptic muscarinic and adenosine receptors. These results support the use of A(2A) receptor antagonists together with atropine to facilitate recovery from

  10. 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

  11. 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.

  12. Sex- and Age-dependent Effects of Orexin 1 Receptor Blockade on Open-Field Behavior and Neuronal Activity.

    PubMed

    Blume, Shannon R; Nam, Hannah; Luz, Sandra; Bangasser, Debra A; Bhatnagar, Seema

    2018-06-15

    Adolescence is a sensitive and critical period in brain development where psychiatric disorders such as anxiety, depression and post-traumatic stress disorder are more likely to emerge following a stressful life event. Females are two times more likely to suffer from psychiatric disorders than males. Patients with these disorders show alterations in orexins (also called hypocretins), important neuropeptides that regulate arousal, wakefulness and the hypothalamic-pituitary-adrenal axis activity. Little is known on the role of orexins in mediating arousal behaviors in male and female rats during adolescence or adulthood. Here, we examine the influence of orexin 1 receptor blockade by SB334867 in open-field behavior in male and female rats during early adolescence (PND 31-33) or adulthood (PND 75-77). Animals were injected with 0 (vehicle), 1, 10, or 30 mg/kg SB334867 (i.p.). Thirty minutes later, they were placed in an open field, and behavior and neuronal activity (c-Fos) were assessed. In adolescent males, SB334867 significantly increased immobility in the 10 mg/kg group compared to vehicle. However, this increase in immobility in adolescent males was not observed in adolescent females. In contrast to adolescent males, adult males in the 10 mg/kg dose group showed the opposite effect on immobility compared to vehicle. These results indicate that 10 mg/kg dose of SB334867 has opposing effects in adolescent and adult males, but few effects in adolescent and adult females. Differences in functional networks between limbic regions may underlie these effects of orexin receptor blockade that are sex- and age-dependent in rats. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

  13. Chronic neonatal N-methyl-D-aspartate receptor blockade induces learning deficits and transient hypoactivity in young rats.

    PubMed

    Latysheva, Nadejda V; Rayevsky, Kirill S

    2003-08-01

    A blockade of N-methyl-D-aspartate (NMDA)-type of glutamate receptor in rodents is believed to provide a pharmacological model of schizophrenia-related psychosis. Since neurodevelopmental abnormality, at least partly, could contribute to the pathogenesis of schizophrenia, the aim of this study was to recapitulate cognitive impairments accompanying this disorder in rats by a chronic neonatal treatment with a noncompetitive NMDA antagonist MK-801. Rat pups were treated with a low dose of MK-801 (0.05 mg/kg s.c.) chronically from early postnatal period (PD 7-49) known to be critical for glutamatergic system maturation. Locomotor activity in the "open-field" test, anxiety level in the elevated plus-maze test, and learning capacity in food rewarded spatial task were examined in young animals. Chronic MK-801 treatment produced a decrease of spontaneous motor and exploratory activity in 16- to 28-day-old rats. At the same time, a hyperlocomotion in response to acute administration of MK-801 was observed as well. Spatial learning of MK-801-treated rats was found to be negatively affected. Treated rats were able to respond to stress stimuli in the adequate manner but their anxiety level was found to be lower than in controls. Behavioral disturbances appeared to be temporary, and no such abnormalities could be detected at the age of 16 weeks. Thus, even mild chronic neonatal blockade of NMDA receptors may lead to a specific pattern of cognitive abnormalities presumably resulting from impairments of sensory information processing at the cortical-basal ganglia level.

  14. Combined unilateral blockade of cholinergic, peptidergic, and serotonergic receptors in the ventral respiratory column does not affect breathing in awake or sleeping goats

    PubMed Central

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

    2015-01-01

    Previous work in intact awake and sleeping goats has found that unilateral blockade of excitatory inputs in the ventral respiratory column (VRC) elicits changes in the concentrations of multiple neurochemicals, including serotonin (5-HT), substance P, glycine, and GABA, while increasing or having no effect on breathing. These findings are consistent with the concept of interdependence between neuromodulators, whereby attenuation of one modulator elicits compensatory changes in other modulators to maintain breathing. Because there is a large degree of redundancy and multiplicity of excitatory inputs to the VRC, we herein tested the hypothesis that combined unilateral blockade of muscarinic acetylcholine (mACh), neurokinin-1 (NK1, the receptor for substance P), and 5-HT2A receptors would elicit changes in multiple neurochemicals, but would not change breathing. We unilaterally reverse-dialyzed a cocktail of antagonists targeting these receptors into the VRC of intact adult goats. Breathing was continuously monitored while effluent fluid from dialysis was collected for quantification of neurochemicals. We found that neither double blockade of mACh and NK1 receptors, nor triple blockade of mACh, NK1, and 5-HT2A receptors significantly affected breathing (P ≥ 0.05) in goats that were awake or in non-rapid eye movement (NREM) sleep. However, both double and triple blockade increased the effluent concentration of substance P (P < 0.001) and decreased GABA concentrations. These findings support our hypothesis and, together with past data, suggest that both in wakefulness and NREM sleep, multiple neuromodulator systems collaborate to stabilize breathing when a deficit in one or multiple excitatory neuromodulators exists. PMID:26023224

  15. 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.

  16. 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.

  17. Measuring specific receptor binding of a PET radioligand in human brain without pharmacological blockade: The genomic plot.

    PubMed

    Veronese, Mattia; Zanotti-Fregonara, Paolo; Rizzo, Gaia; Bertoldo, Alessandra; Innis, Robert B; Turkheimer, Federico E

    2016-04-15

    PET studies allow in vivo imaging of the density of brain receptor species. The PET signal, however, is the sum of the fraction of radioligand that is specifically bound to the target receptor and the non-displaceable fraction (i.e. the non-specifically bound radioligand plus the free ligand in tissue). Therefore, measuring the non-displaceable fraction, which is generally assumed to be constant across the brain, is a necessary step to obtain regional estimates of the specific fractions. The nondisplaceable binding can be directly measured if a reference region, i.e. a region devoid of any specific binding, is available. Many receptors are however widely expressed across the brain, and a true reference region is rarely available. In these cases, the nonspecific binding can be obtained after competitive pharmacological blockade, which is often contraindicated in humans. In this work we introduce the genomic plot for estimating the nondisplaceable fraction using baseline scans only. The genomic plot is a transformation of the Lassen graphical method in which the brain maps of mRNA transcripts of the target receptor obtained from the Allen brain atlas are used as a surrogate measure of the specific binding. Thus, the genomic plot allows the calculation of the specific and nondisplaceable components of radioligand uptake without the need of pharmacological blockade. We first assessed the statistical properties of the method with computer simulations. Then we sought ground-truth validation using human PET datasets of seven different neuroreceptor radioligands, where nonspecific fractions were either obtained separately using drug displacement or available from a true reference region. The population nondisplaceable fractions estimated by the genomic plot were very close to those measured by actual human blocking studies (mean relative difference between 2% and 7%). However, these estimates were valid only when mRNA expressions were predictive of protein levels (i

  18. Measuring specific receptor binding of a PET radioligand in human brain without pharmacological blockade: The genomic plot

    PubMed Central

    Veronese, Mattia; Zanotti-Fregonara, Paolo; Rizzo, Gaia; Bertoldo, Alessandra; Innis, Robert B.; Turkheimer, Federico E.

    2016-01-01

    PET studies allow in vivo imaging of the density of brain receptor species. The PET signal, however, is the sum of the fraction of radioligand that is specifically bound to the target receptor and the non-displaceable fraction (i.e. the non-specifically bound radioligand plus the free ligand in tissue). Therefore, measuring the non-displaceable fraction, which is generally assumed to be constant across the brain, is a necessary step to obtain regional estimates of the specific fractions. The nondisplaceable binding can be directly measured if a reference region, i.e. a region devoid of any specific binding, is available. Many receptors are however widely expressed across the brain, and a true reference region is rarely available. In these cases, the nonspecific binding can be obtained after competitive pharmacological blockade, which is often contraindicated in humans. In this work we introduce the genomic plot for estimating the nondisplaceable fraction using baseline scans only. The genomic plot is a transformation of the Lassen graphical method in which the brain maps of mRNA transcripts of the target receptor obtained from the Allen brain atlas are used as a surrogate measure of the specific binding. Thus, the genomic plot allows the calculation of the specific and nondisplaceable components of radioligand uptake without the need of pharmacological blockade. We first assessed the statistical properties of the method with computer simulations. Then we sought ground-truth validation using human PET datasets of seven different neuroreceptor radioligands, where nonspecific fractions were either obtained separately using drug displacement or available from a true reference region. The population nondisplaceable fractions estimated by the genomic plot were very close to those measured by actual human blocking studies (mean relative difference between 2% and 7%). However, these estimates were valid only when mRNA expressions were predictive of protein levels (i

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. Endocannabinoid receptor blockade increases vascular endothelial growth factor and inflammatory markers in obese women with polycystic ovary syndrome.

    PubMed

    Sathyapalan, Thozhukat; Javed, Zeeshan; Kilpatrick, Eric S; Coady, Anne-Marie; Atkin, Stephen L

    2017-03-01

    Animal studies suggest that cannabinoid receptor-1 (CB-1) blockade reduces inflammation and neovascularization by decreasing vascular endothelial growth factor (VEGF) levels associated with a reduction in inflammatory markers, thereby potentially reducing cardiovascular risk. To determine the impact of CB1 antagonism by rimonabant on VEGF and inflammatory markers in obese PCOS women. Randomized, open-labelled parallel study. Endocrinology outpatient clinic in a referral centre. Twenty patients with PCOS (PCOS) and biochemical hyperandrogenaemia with a body mass index of ≥30 kg/m 2 were recruited. Patients were randomized to 1·5 g daily of metformin or 20 mg daily of rimonabant. Post hoc review to detect VEGF and pro-inflammatory cytokines TNF-α, IL-1β, IL-1ra, IL-2, IL6, IL-8, IL-10 and MCP-1 before and after 12 weeks of treatment. After 12 weeks of rimonabant treatment, there was a significant increase in VEGF (99·2 ± 17·6 vs 116·2 ± 15·8 pg/ml, P < 0·01) and IL-8 (7·4 ± 11·0 vs 18·1 ± 13·2 pg/ml, P < 0·05) but not after metformin (VEGF P = 0·7; IL-8 P = 0·9). There was no significant difference in the pro-inflammatory cytokines TNF-α, IL-1β, IL-1ra, IL-2, IL6, IL-8, IL-10 and MCP-1 following either treatment. This study suggests that rimonabant CB-I blockade paradoxically raised VEGF and the cytokine IL-8 in obese women with PCOS that may have offset the potential benefit associated with weight loss. © 2016 John Wiley & Sons Ltd.

  4. Nogo receptor blockade overcomes remyelination failure after white matter stroke and stimulates functional recovery in aged mice

    PubMed Central

    Sozmen, Elif G.; Rosenzweig, Shira; Llorente, Irene L.; DiTullio, David J.; Machnicki, Michal; Vinters, Harry V.; Havton, Lief A.; Giger, Roman J.; Hinman, Jason D.

    2016-01-01

    White matter stroke is a distinct stroke subtype, accounting for up to 25% of stroke and constituting the second leading cause of dementia. The biology of possible tissue repair after white matter stroke has not been determined. In a mouse stroke model, white matter ischemia causes focal damage and adjacent areas of axonal myelin disruption and gliosis. In these areas of only partial damage, local white matter progenitors respond to injury, as oligodendrocyte progenitors (OPCs) proliferate. However, OPCs fail to mature into oligodendrocytes (OLs) even in regions of demyelination with intact axons and instead divert into an astrocytic fate. Local axonal sprouting occurs, producing an increase in unmyelinated fibers in the corpus callosum. The OPC maturation block after white matter stroke is in part mediated via Nogo receptor 1 (NgR1) signaling. In both aged and young adult mice, stroke induces NgR1 ligands and down-regulates NgR1 inhibitors during the peak OPC maturation block. Nogo ligands are also induced adjacent to human white matter stroke in humans. A Nogo signaling blockade with an NgR1 antagonist administered after stroke reduces the OPC astrocytic transformation and improves poststroke oligodendrogenesis in mice. Notably, increased white matter repair in aged mice is translated into significant poststroke motor recovery, even when NgR1 blockade is provided during the chronic time points of injury. These data provide a perspective on the role of NgR1 ligand function in OPC fate in the context of a specific and common type of stroke and show that it is amenable to systemic intervention to promote recovery. PMID:27956620

  5. Nogo receptor blockade overcomes remyelination failure after white matter stroke and stimulates functional recovery in aged mice.

    PubMed

    Sozmen, Elif G; Rosenzweig, Shira; Llorente, Irene L; DiTullio, David J; Machnicki, Michal; Vinters, Harry V; Havton, Lief A; Giger, Roman J; Hinman, Jason D; Carmichael, S Thomas

    2016-12-27

    White matter stroke is a distinct stroke subtype, accounting for up to 25% of stroke and constituting the second leading cause of dementia. The biology of possible tissue repair after white matter stroke has not been determined. In a mouse stroke model, white matter ischemia causes focal damage and adjacent areas of axonal myelin disruption and gliosis. In these areas of only partial damage, local white matter progenitors respond to injury, as oligodendrocyte progenitors (OPCs) proliferate. However, OPCs fail to mature into oligodendrocytes (OLs) even in regions of demyelination with intact axons and instead divert into an astrocytic fate. Local axonal sprouting occurs, producing an increase in unmyelinated fibers in the corpus callosum. The OPC maturation block after white matter stroke is in part mediated via Nogo receptor 1 (NgR1) signaling. In both aged and young adult mice, stroke induces NgR1 ligands and down-regulates NgR1 inhibitors during the peak OPC maturation block. Nogo ligands are also induced adjacent to human white matter stroke in humans. A Nogo signaling blockade with an NgR1 antagonist administered after stroke reduces the OPC astrocytic transformation and improves poststroke oligodendrogenesis in mice. Notably, increased white matter repair in aged mice is translated into significant poststroke motor recovery, even when NgR1 blockade is provided during the chronic time points of injury. These data provide a perspective on the role of NgR1 ligand function in OPC fate in the context of a specific and common type of stroke and show that it is amenable to systemic intervention to promote recovery.

  6. 5-HT6 receptor blockade regulates primary cilia morphology in striatal neurons.

    PubMed

    Brodsky, Matthew; Lesiak, Adam J; Croicu, Alex; Cohenca, Nathalie; Sullivan, Jane M; Neumaier, John F

    2017-04-01

    The 5-HT 6 receptor has been implicated in a variety of cognitive processes including habitual behaviors, learning, and memory. It is found almost exclusively in the brain, is expressed abundantly in striatum, and localizes to neuronal primary cilia. Primary cilia are antenna-like, sensory organelles found on most neurons that receive both chemical and mechanical signals from other cells and the surrounding environment; however, the effect of 5-HT 6 receptor function on cellular morphology has not been examined. We confirmed that 5-HT 6 receptors were localized to primary cilia in wild-type (WT) but not 5-HT 6 knockout (5-HT 6 KO) in both native mouse brain tissue and primary cultured striatal neurons then used primary neurons cultured from WT or 5-HT 6 KO mice to study the function of these receptors. Selective 5-HT 6 antagonists reduced cilia length in neurons cultured from wild-type mice in a concentration and time-dependent manner without altering dendrites, but had no effect on cilia length in 5-HT 6 KO cultured neurons. Varying the expression levels of heterologously expressed 5-HT 6 receptors affected the fidelity of ciliary localization in both WT and 5-HT 6 KO neurons; overexpression lead to increasing amounts of 5-HT 6 localization outside of the cilia but did not alter cilia morphology. Introducing discrete mutations into the third cytoplasmic loop of the 5-HT 6 receptor greatly reduced, but did not entirely eliminate, trafficking of the 5-HT 6 receptor to primary cilia. These data suggest that blocking 5-HT 6 receptor activity reduces the length of primary cilia and that mechanisms that regulate trafficking of 5-HT 6 receptors to cilia are more complex than previously thought. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Blockade of human P2X7 receptor function with a monoclonal antibody.

    PubMed

    Buell, G; Chessell, I P; Michel, A D; Collo, G; Salazzo, M; Herren, S; Gretener, D; Grahames, C; Kaur, R; Kosco-Vilbois, M H; Humphrey, P P

    1998-11-15

    A monoclonal antibody (MoAb) specific for the human P2X7 receptor was generated in mice. As assessed by flow cytometry, the MoAb labeled human blood-derived macrophage cells natively expressing P2X7 receptors and cells transfected with human P2X7 but not other P2X receptor types. The MoAb was used to immunoprecipitate the human P2X7 receptor protein, and in immunohistochemical studies on human lymphoid tissue, P2X7 receptor labeling was observed within discrete areas of the marginal zone of human tonsil sections. The antibody also acted as a selective antagonist of human P2X7 receptors in several functional studies. Thus, whole cell currents, elicited by the brief application of 2',3'-(4-benzoyl)-benzoyl-ATP in cells expressing human P2X7, were reduced in amplitude by the presence of the MoAb. Furthermore, preincubation of human monocytic THP-1 cells with the MoAb antagonized the ability of P2X7 agonists to induce the release of interleukin-1beta.

  8. AMP is an adenosine A1 receptor agonist.

    PubMed

    Rittiner, Joseph E; Korboukh, Ilia; Hull-Ryde, Emily A; Jin, Jian; Janzen, William P; Frye, Stephen V; Zylka, Mark J

    2012-02-17

    Numerous receptors for ATP, ADP, and adenosine exist; however, it is currently unknown whether a receptor for the related nucleotide adenosine 5'-monophosphate (AMP) exists. Using a novel cell-based assay to visualize adenosine receptor activation in real time, we found that AMP and a non-hydrolyzable AMP analog (deoxyadenosine 5'-monophosphonate, ACP) directly activated the adenosine A(1) receptor (A(1)R). In contrast, AMP only activated the adenosine A(2B) receptor (A(2B)R) after hydrolysis to adenosine by ecto-5'-nucleotidase (NT5E, CD73) or prostatic acid phosphatase (PAP, ACPP). Adenosine and AMP were equipotent human A(1)R agonists in our real-time assay and in a cAMP accumulation assay. ACP also depressed cAMP levels in mouse cortical neurons through activation of endogenous A(1)R. Non-selective purinergic receptor antagonists (pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid and suramin) did not block adenosine- or AMP-evoked activation. Moreover, mutation of His-251 in the human A(1)R ligand binding pocket reduced AMP potency without affecting adenosine potency. In contrast, mutation of a different binding pocket residue (His-278) eliminated responses to AMP and to adenosine. Taken together, our study indicates that the physiologically relevant nucleotide AMP is a full agonist of A(1)R. In addition, our study suggests that some of the physiological effects of AMP may be direct, and not indirect through ectonucleotidases that hydrolyze this nucleotide to adenosine.

  9. Opposing effects of AMPA and 5-HT1A receptor blockade on passive avoidance and object recognition performance: correlation with AMPA receptor subunit expression in rat hippocampus.

    PubMed

    Schiapparelli, L; Simón, A M; Del Río, J; Frechilla, D

    2006-06-01

    It has been suggested that antagonists at serotonin 5-HT1A receptors may exert a procognitive effect by facilitating glutamatergic neurotransmission. Here we further explored this issue by looking for the ability of a 5-HT1A antagonist to prevent the learning deficit induced by AMPA receptor blockade in two behavioural procedures in rats, and for concomitant molecular changes presumably involved in memory formation in the hippocampus. Pretraining administration of the competitive AMPA receptor antagonist, NBQX, produced a dose-related retention impairment in a passive avoidance task 24h later, and also impaired retention in a novel object recognition test when an intertrial interval of 3h was selected. Pretreatment with the selective 5-HT1A receptor antagonist, WAY-100635, prevented the learning deficit induced by NBQX in the two behavioural procedures. In biochemical studies performed on rat hippocampus after the retention tests, we found that learning increased the membrane levels of AMPA receptor GluR1 and GluR2/3 subunits, as well as the phosphorylated forms of GluR1, effects that were abolished by NBQX administration before the training session. Pretreatment with WAY-100635 counteracted the NBQX effects and restored the initial learning-specific increase in Ca2+/calmodulin-dependent protein kinase II (CaMKII) function and the later increase in GluR2/3 and phosphorylated GluR1 surface expression. Moreover, administration of WAY-100635 before object recognition training improved recognition memory 24h later and potentiated the learning-associated increase in AMPA receptor subunits. The results support the proposed utility of 5-HT1A antagonists in the treatment of cognitive disorders.

  10. Opioid receptor blockade and warmth-liking: effects on interpersonal trust and frontal asymmetry

    PubMed Central

    Schweiger, Desirée; Stemmler, Gerhard; Burgdorf, Christin

    2014-01-01

    The emotion ‘warmth-liking’ (WL) associated with feelings of affection and acceptance is regularly activated in social contexts. WL has been suggested to be more closely related to the consummatory phase of post-goal attainment positive affect than to pre-goal attainment positive affect/approach motivation and to be partly mediated by brain opioids. To validate these assumptions we employed film/imagery to induce either a neutral emotional state or WL in female participants after intake of either placebo or the opioid antagonist naltrexone. Dependent variables were emotion self-report, interpersonal trust (TRUST, i.e. a behavioral indicator of WL) and frontal asymmetry (i.e. an electroencephalogram (EEG) indicator of approach motivation/behavioral activation). We found that participants reported more WL in the placebo/WL group than in the placebo/neutral group and both naltrexone groups. In addition, TRUST increased in the WL group after placebo, but not after naltrexone, and this pattern was reversed in the neutral control groups. Consequently, opioid blockade suppressed or even reversed the effects of the WL induction on the levels of self-report and behavior, respectively. In addition, we observed reduced relative left-frontal asymmetry in the WL (vs neutral) group, consistent with reduced approach motivation. Overall, these results suggest opioidergic influences on WL and TRUST and reduced approach motivation/behavioral activation for the positive emotion WL. PMID:24078107

  11. Blockade of central vasopressin receptors reduces the cardiovascular response to acute stress in freely moving rats.

    PubMed

    Stojicić, S; Milutinović-Smiljanić, S; Sarenac, O; Milosavljević, S; Paton, J F R; Murphy, D; Japundzić-Zigon, N

    2008-04-01

    To investigate the contribution of central vasopressin receptors to blood pressure (BP) and heart rate (HR) response to stress we injected non-peptide selective V(1a) (SR49059), V(1b) (SSR149415), V(2) (SR121463) receptor antagonists, diazepam or vehicle in the lateral cerebral ventricle of conscious freely moving rats stressed by blowing air on their heads for 2 min. Cardiovascular effects of stress were evaluated by analyzing maximum increase of BP and HR (MAX), latency of maximum response (LAT), integral under BP and HR curve (integral), duration of their recovery and spectral parameters of BP and HR indicative of increased sympathetic outflow (LF(BP) and LF/HF(HR)). Moreover, the increase of serum corticosterone was measured. Exposure to air-jet stress induced simultaneous increase in BP and HR followed by gradual decline during recovery while LF(BP) oscillation remained increased as well as serum corticosterone level. Rats pre-treated with vasopressin receptor antagonists were not sedated while diazepam induced sedation that persisted during exposure to stress. V(1a), V(1b) and V(2) receptor antagonists applied separately did not modify basal values of cardiovascular parameters but prevented the increase in integral(BP). In addition, V(1b) and V(2) receptor antagonists reduced BP(MAX) whereas V(1a), V(1b) antagonist and diazepam reduced HR(MAX) induced by exposure to air-jet stress. All drugs shortened the recovery period, prevented the increase of LF(BP) without affecting the increase in serum corticosterone levels. Results indicate that vasopressin receptors located within the central nervous system mediate, in part, the cardiovascular response to air-jet stress without affecting either the neuroendocrine component or inducing sedation. They support the view that the V(1b) receptor antagonist may be of potential therapeutic value in reducing arterial pressure induced by stress-related disorders.

  12. Up-Regulation of Endothelin Type A Receptor in Human and Rat Radiation Proctitis: Preclinical Therapeutic Approach With Endothelin Receptor Blockade

    SciTech Connect

    Jullien, Nicolash; Blirando, Karl; Milliat, Fabien

    2009-06-01

    Purpose: Rectum radiation damage and fibrosis are often associated with radiation therapy of pelvic tumors. The endothelin (ET) system has been implicated in several fibrotic diseases but never studied in the context of gastrointestinal radiation damage. This study assessed modifications in ET type 1 (ET-1), ET type A receptor (ET{sub A}), and ET type B receptor (ET{sub B}) localization and/or expression in irradiated human rectal tissue and in a rat model of delayed colorectal injury. We also evaluated the therapeutic potential of long-term ET receptor blockade. Methods and Materials: Routine histological studies of sections of healthy and radiation-injured human rectummore » tissue were done; the sections were also immunostained for ET{sub A} and ET{sub B} receptors. The rat model involved the delivery of 27 Gy in a single dose to the colons and rectums of the animals. The ET-1/ET{sub A}/ET{sub B} expression and ET{sub A}/ET{sub B} localization were studied at 10 weeks postexposure. The abilities of bosentan and atrasentan to protect against delayed rectal injury were also investigated. Results: The immunolocalization of ET{sub A} and ET{sub B} in healthy human rectums was similar to that in rat rectums. However, strong ET{sub A} immunostaining was seen in the presence of human radiation proctitis, and increased ET{sub A} mRNA levels were seen in the rat following colorectal irradiation. Immunostaining for ET{sub A} was also strongly positive in rats in areas of radiation-induced mucosal ulceration, atypia, and fibroproliferation. However, neither bosentan nor atrasentan prevented radiation damage to the rectum when given long term. The only effect seen for atrasentan was an increased number of sclerotic vessel sections in injured tissues. Conclusions: As the result of the overexpression of ET{sub A}, radiation exposure deregulates the endothelin system through an 'ET{sub A} profile' in the human and rodent rectum. However, therapeutic interventions involving

  13. 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.

  14. Blockade of renal medullary bradykinin B2 receptors increases tubular sodium reabsorption in rats fed a normal-salt diet

    PubMed Central

    Sivritas, Sema-Hayriye; Ploth, David W.; Fitzgibbon, Wayne R.

    2008-01-01

    The present study was performed to test the hypothesis that under normal physiological conditions and/or during augmentation of kinin levels, intrarenal kinins act on medullary bradykinin B2 (BKB2) receptors to acutely increase papillary blood flow (PBF) and therefore Na+ excretion. We determined the effect of acute inner medullary interstitial (IMI) BKB2 receptor blockade on renal hemodynamics and excretory function in rats fed either a normal (0.23%)- or a low (0.08%)-NaCl diet. For each NaCl diet, two groups of rats were studied. Baseline renal hemodynamic and excretory function were determined during IMI infusion of 0.9% NaCl into the left kidney. The infusion was then either changed to HOE-140 (100 μg·kg−1·h−1, treated group) or maintained with 0.9% NaCl (time control group), and the parameters were again determined. In rats fed a normal-salt diet, HOE-140 infusion decreased left kidney Na+ excretion (urinary Na+ extraction rate) and fractional Na+ excretion by 40 ± 5% and 40 ± 4%, respectively (P < 0.01), but did not alter glomerular filtration rate, inner medullary blood flow (PBF), or cortical blood flow. In rats fed a low-salt diet, HOE-140 infusion did not alter renal regional hemodynamics or excretory function. We conclude that in rats fed a normal-salt diet, kinins act tonically via medullary BKB2 receptors to increase Na+ excretion independent of changes in inner medullary blood flow. PMID:18632797

  15. Both genetic deletion and pharmacological blockade of lysophosphatidic acid LPA1 receptor results in increased alcohol consumption.

    PubMed

    Castilla-Ortega, Estela; Pavón, Francisco Javier; Sánchez-Marín, Laura; Estivill-Torrús, Guillermo; Pedraza, Carmen; Blanco, Eduardo; Suárez, Juan; Santín, Luis; Rodríguez de Fonseca, Fernando; Serrano, Antonia

    2016-04-01

    Lysophosphatidic acid species (LPA) are lipid bioactive signaling molecules that have been recently implicated in the modulation of emotional and motivational behaviors. The present study investigates the consequences of either genetic deletion or pharmacological blockade of lysophosphatidic acid receptor-1 (LPA1) in alcohol consumption. The experiments were performed in alcohol-drinking animals by using LPA1-null mice and administering the LPA1 receptor antagonist Ki16425 in both mice and rats. In the two-bottle free choice paradigm, the LPA1-null mice preferred the alcohol more than their wild-type counterparts. Whereas the male LPA1-null mice displayed this higher preference at all doses tested, the female LPA1-null mice only consumed more alcohol at 6% concentration. The male LPA1-null mice were then further characterized, showing a notably increased ethanol drinking after a deprivation period and a reduced sleep time after acute ethanol administration. In addition, LPA1-null mice were more anxious than the wild-type mice in the elevated plus maze test. For the pharmacological experiments, the acute administration of the antagonist Ki16425 consistently increased ethanol consumption in both wild-type mice and rats; while it did not modulate alcohol drinking in the LPA1-null mice and lacked intrinsic rewarding properties and locomotor effects in a conditioned place preference paradigm. In addition, LPA1-null mice exhibited a marked reduction on the expression of glutamate-transmission-related genes in the prefrontal cortex similar to those described in alcohol-exposed rodents. Results suggest a relevant role for the LPA/LPA1 signaling system in alcoholism. In addition, the LPA1-null mice emerge as a new model for genetic vulnerability to excessive alcohol drinking. The pharmacological manipulation of LPA1 receptor arises as a new target for the study and treatment of alcoholism. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Dissociation between cardiomyocyte function and remodeling with beta-adrenergic receptor blockade in isolated canine mitral regurgitation.

    PubMed

    Pat, Betty; Killingsworth, Cheryl; Denney, Thomas; Zheng, Junying; Powell, Pamela; Tillson, Michael; Dillon, A Ray; Dell'Italia, Louis J

    2008-12-01

    The low-pressure volume overload of isolated mitral regurgitation (MR) is associated with increased adrenergic drive, left ventricular (LV) dilatation, and loss of interstitial collagen. We tested the hypothesis that beta1-adrenergic receptor blockade (beta1-RB) would attenuate LV remodeling after 4 mo of MR in the dog. beta1-RB did not attenuate collagen loss or the increase in LV mass in MR dogs. Using MRI and three-dimensional (3-D) analysis, there was a 70% increase in the LV end-diastolic (LVED) volume-to-LV mass ratio, a 23% decrease in LVED midwall circumferential curvature, and a >50% increase in LVED 3-D radius/wall thickness in MR dogs that was not attenuated by beta1-RB. However, beta1-RB caused a significant increase in LVED length from the base to apex compared with untreated MR dogs. This was associated with an increase in isolated cardiomyocyte length (171+/-5 microm, P<0.05) compared with normal (156+/-3 microm) and MR (165+/-4 microm) dogs. Isolated cardiomyocyte fractional shortening was significantly depressed in MR dogs compared with normal dogs (3.73+/-0.31 vs. 5.02+/-0.26%, P<0.05) and normalized with beta1-RB (4.73+/-0.48%). In addition, stimulation with the beta-adrenergic receptor agonist isoproterenol (25 nM) increased cardiomyocyte fractional shortening by 215% (P<0.05) in beta1-RB dogs compared with normal (56%) and MR (50%) dogs. In summary, beta1-RB improved LV cardiomyocyte function and beta-adrenergic receptor responsiveness despite further cell elongation. The failure to attenuate LV remodeling associated with MR could be due to a failure to improve ultrastructural changes in extracellular matrix organization.

  17. Combined blockade of angiotensin II and prorenin receptors ameliorates podocytic apoptosis induced by IgA-activated mesangial cells.

    PubMed

    Leung, Joseph C K; Chan, Loretta Y Y; Saleem, M A; Mathieson, P W; Tang, Sydney C W; Lai, Kar Neng

    2015-07-01

    Glomerulo-podocytic communication plays an important role in the podocytic injury in IgA nephropathy (IgAN). In this study, we examine the role of podocytic angiotensin II receptor subtype 1 (AT1R) and prorenin receptor (PRR) in podocytic apoptosis in IgAN. Polymeric IgA (pIgA) was isolated from patients with IgAN and healthy controls. Conditioned media were prepared from growth arrested human mesangial cells (HMC) incubated with pIgA from patients with IgAN (IgA-HMC media) or healthy controls (Ctl-HMC media). A human podocyte cell line was used as a model to examine the regulation of the expression of AT1R, PRR, TNF-α and CTGF by IgA-HMC media. Podocytic nephrin expression, annexin V binding and caspase 3 activity were used as the functional readout of podocytic apoptosis. IgA-HMC media had no effect on AngII release by podocytes. IgA-HMC media significantly up-regulated the expression of AT1R and PRR, down-regulated nephrin expression and induced apoptosis in podocytes. Mono-blockade of AT1R, PRR, TNF-α or CTGF partially reduced podocytic apoptosis. IgA-HMC media activated NFκB, notch1 and HEY1 expression by podocytes and dual blockade of AT1R with PRR, or anti-TNF-α with anti-CTGF, effectively rescued the podocytic apoptosis induced by IgA-HMC media. Our data suggests that pIgA-activated HMC up-regulates the expression of AT1R and PRR expression by podocytes and the associated activation of NFκB and notch signalling pathways play an essential role in the podocytic apoptosis induced by glomerulo-podocytic communication in IgAN. Simultaneously targeting the AT1R and PRR could be a potential therapeutic option to reduce the podocytic injury in IgAN.

  18. Effect of endothelin-1 and endothelin receptor blockade on the release of microparticles.

    PubMed

    Jung, Christian; Lichtenauer, Michael; Wernly, Bernhard; Franz, Marcus; Goebel, Bjoern; Rafnsson, Arnar; Figulla, Hans-Reiner; Pernow, John

    2016-08-01

    Increased levels of endothelial cell microparticles (EMP) are known to reflect endothelial dysfunction (ED). In diabetes mellitus type 2 (T2DM), the expression of endothelin (ET)-1 is increased. As treatment with an ET-1 antagonist significantly inhibited atherosclerosis in animal models, we sought to investigate whether treatment with ET-1 antagonists affects EMP levels in vitro and in vivo in patients with T2DM. In vitro study: Human umbilical vein endothelial cells (HUVEC) were stimulated with ET-1 alone and ET-1 in combination with a dual ET-A and ET-B endothelin receptor blocker. In vivo study: Patients with T2DM were randomized to treatment with the ET receptor antagonist bosentan or placebo. After 4 weeks, the patients were re-examined and blood samples were obtained. EMP counts in supernatants and plasma samples were determined using flow cytometry. In vitro study: In supernatants of ET-1-stimulated HUVECs, the increased release of EMP was reduced significantly by co-incubation with an ET-1 receptor antagonist (e.g. CD31+/CD42b-EMP decreased from 37·1% ± 2·8 to 31·5% ± 2·8 SEM, P = 0·0078). In vivo study: No changes in EMP levels in blood samples of patients with T2DM were found after 4 weeks of bosentan treatment (n = 36, P = ns). Our in vitro results suggest that ET-1 stimulates the release of EMP from HUVECs via a receptor-dependent mechanism. Co-incubation with an endothelin receptor blocker abolished ET-1-dependent EMP release. However, treatment with bosentan for 4 weeks failed to alter EMP levels in patients with T2DM. Other factors seem to have influenced EMP release in patients with T2DM independent of ET-1 receptor-mediated mechanisms. © 2016 Stichting European Society for Clinical Investigation Journal Foundation.

  19. 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.

  20. Angiotensin receptor blockade: a novel approach for symptomatic radiation necrosis after stereotactic radiosurgery

    PubMed Central

    Okwan-Duodu, Derick; Switchenko, Jeffrey M.; Press, Robert H.; Jhaveri, Jaymin; Buchwald, Zachary S.; Zhong, Jim; Chapman, Bhavana V.; Bindra, Ranjit S.; Contessa, Joseph N.; Park, Henry S.; Yu, James B.; Decker, Roy H.; Olson, Jeffrey J.; Oyesiku, Nelson M.; Abrams, Ross A.; Shu, Hui-Kuo G.; Curran, Walter J.; Crocker, Ian R.

    2018-01-01

    Preclinical evidence suggests angiotensin blockade therapy (ABT) decreases late radiation toxicities. This study aims to investigate the association between ABT and symptomatic radiation necrosis (SRN) following stereotactic radiosurgery (SRS). Resected brain metastases (rBM) and arteriovenous malformation (AVM) patients treated with SRS from 2002 to 2015 were identified. Patients in the ABT cohort were on therapy during SRS and at 1-month follow up. Kaplan Meier method and cumulative incidence model were used to analyze overall survival (OS) and intracranial outcomes. 228 consecutive patients were treated with SRS: 111 with rBM and 117 with AVM. Overall, 51 (22.4%) patients were in the ABT group: 32 (28.8%) in the rBM and 19 (16.2%) in AVM cohorts. Baseline characteristics were similar, except for higher Graded Prognostic Analysis (3–4) in the rBM (ABT: 25.0% vs. non-ABT: 49.0%, p = 0.033) and median age in the AVM (ABT: 51.4 vs. non-ABT: 35.4, p < 0.001) cohorts. In both populations, OS and intracranial efficacy (rBM—local control; AVM—obliteration rates) were statistically similar between the cohorts. ABT was associated with lower 1-year SRN rates in both populations: rBM, 3.1 versus 25.3% (p = 0.003); AVM, 6.7 vs. 14.6% (p = 0.063). On multivariate analysis, ABT was a significant predictive factor for rBM (HR: 0.17; 95% CI 0.03–0.88, p = 0.035), but did not reach statistical significance for AVM (HR: 0.36; 95% CI 0.09–1.52, p = 0.165). ABT use appears to be associated with a reduced risk of SRN following SRS, without detriment to OS or intracranial efficacy. A prospective trial to validate these findings is warranted. PMID:29124649

  1. Angiotensin receptor blockade: a novel approach for symptomatic radiation necrosis after stereotactic radiosurgery.

    PubMed

    Chowdhary, Mudit; Okwan-Duodu, Derick; Switchenko, Jeffrey M; Press, Robert H; Jhaveri, Jaymin; Buchwald, Zachary S; Zhong, Jim; Chapman, Bhavana V; Bindra, Ranjit S; Contessa, Joseph N; Park, Henry S; Yu, James B; Decker, Roy H; Olson, Jeffrey J; Oyesiku, Nelson M; Abrams, Ross A; Shu, Hui-Kuo G; Curran, Walter J; Crocker, Ian R; Patel, Kirtesh R

    2018-01-01

    Preclinical evidence suggests angiotensin blockade therapy (ABT) decreases late radiation toxicities. This study aims to investigate the association between ABT and symptomatic radiation necrosis (SRN) following stereotactic radiosurgery (SRS). Resected brain metastases (rBM) and arteriovenous malformation (AVM) patients treated with SRS from 2002 to 2015 were identified. Patients in the ABT cohort were on therapy during SRS and at 1-month follow up. Kaplan Meier method and cumulative incidence model were used to analyze overall survival (OS) and intracranial outcomes. 228 consecutive patients were treated with SRS: 111 with rBM and 117 with AVM. Overall, 51 (22.4%) patients were in the ABT group: 32 (28.8%) in the rBM and 19 (16.2%) in AVM cohorts. Baseline characteristics were similar, except for higher Graded Prognostic Analysis (3-4) in the rBM (ABT: 25.0% vs. non-ABT: 49.0%, p = 0.033) and median age in the AVM (ABT: 51.4 vs. non-ABT: 35.4, p < 0.001) cohorts. In both populations, OS and intracranial efficacy (rBM-local control; AVM-obliteration rates) were statistically similar between the cohorts. ABT was associated with lower 1-year SRN rates in both populations: rBM, 3.1 versus 25.3% (p = 0.003); AVM, 6.7 vs. 14.6% (p = 0.063). On multivariate analysis, ABT was a significant predictive factor for rBM (HR: 0.17; 95% CI 0.03-0.88, p = 0.035), but did not reach statistical significance for AVM (HR: 0.36; 95% CI 0.09-1.52, p = 0.165). ABT use appears to be associated with a reduced risk of SRN following SRS, without detriment to OS or intracranial efficacy. A prospective trial to validate these findings is warranted.

  2. 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…

  3. Impulsivity and AMPA receptors: aniracetam ameliorates impulsive behavior induced by a blockade of AMPA receptors in rats.

    PubMed

    Nakamura, K; Kurasawa, M; Shirane, M

    2000-04-17

    The study aimed to ascertain the involvement of central AMPA receptors in impulsive behaviors of aged rats and to examine the effects of aniracetam. Premature response in the two-lever choice reaction task was assessed as an index of impulsivity. Intracerebroventricular injection of 2, 3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline (NBQX), an AMPA receptor antagonist, dose-dependently (10.1-1009 ng/rat) increased only premature response without altering responding speed and choice accuracy 30 min after the injection. Aniracetam (30 mg/kg p.o.), a positive allosteric modulator of AMPA receptors, or AMPA (55.9 ng/rat, co-injected with NBQX) completely restored the NBQX-induced increase in impulsivity. These results indicate that AMPA receptors are tonically involved in the regulation of impulsivity.

  4. Spasticity therapy reacts to astrocyte GluA1 receptor upregulation following spinal cord injury

    PubMed Central

    Gómez-Soriano, Julio; Goiriena, Eider; Taylor, Julian

    2010-01-01

    For almost three decades intrathecal baclofen therapy has been the standard treatment for spinal cord injury spasticity when oral medication is ineffective or produces serious side effects. Although intrathecal baclofen therapy has a good clinical benefit-risk ratio for spinal spasticity, tolerance and the life-threatening withdrawal syndrome present serious problems for its management. Now, in an experimental model of spinal cord injury spasticity, AMPA receptor blockade with NGX424 (Tezampanel) has been shown to reduce stretch reflex activity alone and during tolerance to intrathecal baclofen therapy. These results stem from the observation that GluA1 receptors are overexpressed on reactive astrocytes following experimental ischaemic spinal cord injury. Although further validation is required, the appropriate choice of AMPA receptor antagonists for treatment of stretch hyperreflexia based on our recent understanding of reactive astrocyte neurobiology following spinal cord injury may lead to the development of a better adjunct clinical therapy for spasticity without the side effects of intrathecal baclofen therapy. LINKED ARTICLE This article is a commentary on Oshiro et al., pp. 976–985 of this issue. To view this paper visit http://dx.doi.org/10.1111/j.1476-5381.2010.00954.x PMID:20662840

  5. Effect of combined opioid receptor and α2-adrenoceptor blockade on anxiety and electrically evoked startle responses.

    PubMed

    Vo, Lechi; Drummond, Peter D

    2017-06-01

    The R3 component of the electrically evoked blink reflex may form part of a startle reaction. Acoustic startle responses are augmented by yohimbine, an α 2 -adrenoceptor antagonist that blocks α 2 -autoreceptors, and are potentiated by opioid receptor blockade. To investigate these influences on electrically evoked startle responses, 16 mg yohimbine, with (16 participants) or without 50 mg naltrexone (23 participants), was administered in separate double-blind placebo-controlled cross-over experiments. In each experiment, R3 (a probable component of the startle response) was examined before and after high-frequency electrical stimulation of the forearm, a procedure that initiates inhibitory pain controls. Anxiety and somatic symptoms were greater after yohimbine than placebo, and were potentiated by naltrexone. Pain ratings for the electrically evoked startle stimuli decreased after high-frequency electrical stimulation in the placebo session but remained stable after drug administration. Yohimbine with naltrexone, but not yohimbine alone, also blocked an inhibitory effect of high-frequency electrical stimulation on electrically evoked sharp sensations and R3. Together, the findings suggest that adding naltrexone to yohimbine potentiated anxiety and blocked inhibitory influences of high-frequency electrical stimulation on electrically evoked sensations and startle responses. Thus, opioid peptides could reduce activity in nociceptive and startle-reflex pathways, or inhibit crosstalk between these pathways. Failure of this inhibitory opioid influence might be important in chronically painful conditions that are aggravated by startle stimuli.

  6. The effect of cannabinoid receptor 1 blockade on hepatic free fatty acid profile in mice with nonalcoholic fatty liver disease.

    PubMed

    Jorgačević, Bojan; Vučević, Danijela; Đuričić, Ivana; Šobajić, Slađana; Mladenović, Dušan; Vesković, Milena; Vukićević, Rada Ješić; Radosavljević, Tatjana

    2017-04-01

    We used rimonabant to investigate the role of CB1 receptor on hepatic FFAs profile during NAFLD. Male mice C57BL/6 were divided into: control group fed with control diet 20 weeks (C; n=6); group fed with HFD 20 weeks (HF; n=6); group fed with control diet and treated with rimonabant after 18 weeks (R; n=9); group fed with HFD and treated with rimonabant after 18 weeks (HFR; n=10). Rimonabant (10mg/kg) was administered daily to HFR and R group by oral gavage. Rimonabant decreased liver palmitic acid proportion in HFR group compared to HF group (p<0.05). Liver stearic and oleic acid proportions were decreased in R group compared to control (p<0.01 respectively). Rimonabant increased liver linoleic and arachidonic acid proportions in HFR group compared to HF group (p<0.01 respectively). CB1 blockade may be useful in the treatment of HFD-induced NAFLD due to modulation of plasma lipid and hepatic FFA profile. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. 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.

  8. Pitting type of pretibial edema in a patient with silent thyroiditis successfully treated by angiotensin ii receptor blockade.

    PubMed

    Kazama, Itsuro; Mori, Yoko; Baba, Asuka; Nakajima, Toshiyuki

    2014-01-01

    Female, 56 FINAL DIAGNOSIS: Thyroiditis - silent Symptoms: Palpitations • pretibial pitting edema • short of breath • sweating - Clinical Procedure: - Specialty: Endocrinology and Metabolic. Unknown etiology. Hyper- or hypothyroidism sometimes causes pretibial myxedema characterized by non-pitting infiltration of a proteinaceous ground substance. However, in those patients, the "pitting" type of pretibial edema as a result of increased sodium and fluid retention or vascular hyper-permeability rarely occurs, except in cases complicated by heart failures due to severe cardiomyopathy or pulmonary hypertension. A 56-year-old woman developed bilateral pretibial pitting edema, followed by occasional sweating, palpitations, and shortness of breath, which persisted for more than 2 months. The diagnosis of hyperthyroidism due to silent thyroiditis was supported by elevated levels of free thyroxine (T4) and triiodothyronine (T3), with a marked decrease in thyroid-stimulating hormone (TSH), and the negative results for TSH receptor antibodies with typical findings of destructive thyrotoxicosis. Despite her "pitting" type of pretibial edema, a chest radio-graph demonstrated the absence of cardiomyopathy or congestive heart failure. Oral administration of angiotensin II receptor blocker (ARB) was initiated for her systolic hypertension, with a relatively higher elevation of plasma renin activity compared to that of the aldosterone level. Although the symptoms characteristic to hyperthyroidism, such as increased sweating, palpitations and shortness of breath, slowly improved with a spontaneous resolution of the disease, ARB quickly resolved the pretibial pitting edema shortly after the administration.. In this case, increased activity of the renin-angiotensin-aldosterone system stimulated by thyroid hormone was likely responsible for the patient's pitting type of edema. The pharmacological blockade of the renin-angiotensin-aldosterone system was thought to be effective for

  9. 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.

  10. Treatment of established left ventricular hypertrophy with fibroblast growth factor receptor blockade in an animal model of CKD

    PubMed Central

    Di Marco, Giovana Seno; Reuter, Stefan; Kentrup, Dominik; Grabner, Alexander; Amaral, Ansel Philip; Fobker, Manfred; Stypmann, Jörg; Pavenstädt, Hermann; Wolf, Myles; Faul, Christian; Brand, Marcus

    2014-01-01

    Background Activation of fibroblast growth factor receptor (FGFR)-dependent signalling by FGF23 may contribute to the complex pathogenesis of left ventricular hypertrophy (LVH) in chronic kidney disease (CKD). Pan FGFR blockade by PD173074 prevented development of LVH in the 5/6 nephrectomy rat model of CKD, but its ability to treat and reverse established LVH is unknown. Methods CKD was induced in rats by 5/6 nephrectomy. Two weeks later, rats began treatment with vehicle (0.9% NaCl) or PD173074, 1 mg/kg once-daily for 3 weeks. Renal function was determined by urine and blood analyses. Left ventricular (LV) structure and function were determined by echocardiography, histopathology, staining for myocardial fibrosis (Sirius-Red) and investigating cardiac gene expression profiles by real-time PCR. Results Two weeks after inducing CKD by 5/6 nephrectomy, rats manifested higher (mean ± SEM) systolic blood pressure (208 ± 4 versus 139 ± 3 mmHg; P < 0.01), serum FGF23 levels (1023 ± 225 versus 199 ± 9 pg/mL; P < 0.01) and LV mass (292 ± 9 versus 220 ± 3 mg; P < 0.01) when compared with sham-operated animals. Thereafter, 3 weeks of treatment with PD173074 compared with vehicle did not significantly change blood pressure, kidney function or metabolic parameters, but significantly reduced LV mass (230 ± 14 versus 341 ± 33 mg; P < 0.01), myocardial fibrosis (2.5 ± 0.7 versus 5.4 ± 0.95% staining/field; P < 0.01) and cardiac expression of genes associated with pathological LVH, while significantly increasing ejection fraction (18 versus 2.5% post-treatment increase; P < 0.05). Conclusions FGFR blockade improved cardiac structure and function in 5/6 nephrectomy rats with previously established LVH. These data support FGFR activation as a potentially modifiable, blood pressure-independent molecular mechanism of LVH in CKD. PMID:24875663

  11. 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.

  12. AT1-receptor blockade attenuates outward aortic remodeling associated with diet-induced obesity in mice.

    PubMed

    Krueger, Friedrich; Kappert, Kai; Foryst-Ludwig, Anna; Kramer, Frederike; Clemenz, Markus; Grzesiak, Aleksandra; Sommerfeld, Manuela; Paul Frese, Jan; Greiner, Andreas; Kintscher, Ulrich; Unger, Thomas; Kaschina, Elena

    2017-08-01

    The renin-angiotensin system (RAS) and obesity have been implicated in vascular outward remodeling, including aneurysms, but the precise mechanisms are not yet understood. We investigated the effect of the angiotensin receptor type 1 (AT1-receptor) antagonist telmisartan on aortic outward remodeling in a diet-induced obesity model in mice. C57/Black6J mice were fed either a low-fat diet (LFD) or a high-fat diet (HFD) for 14 weeks. One group of HFD mice was additionally exposed to telmisartan (3 mg/kg per day) for the last 4 weeks. HFD led to aortic outward remodeling, characterized by increased proteolysis, along with structural changes, such as fragmentation of elastic fibers and decreased elastin content. Vascular damage was associated with up-regulation of matrix metalloproteinase (MMP)-2 (MMP-2), MMP-3, MMP-12, cathepsin D, and cathepsin B. HFD aortae exhibited an enhanced inflammatory status, characterized by tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β) colocalized with adipocytes in the adventitia. HFD resulted in a significant increase in aortic dimensions, evident by ultrasound measurements. Telmisartan abolished aortic dilatation and preserved elastin content. HFD induced enhanced expression of aortic MMP-2, MMP-9, and TNF-α was abrogated by telmisartan. Adventitial proteolytic and inflammatory factors were also examined in samples from human abdominal aneurysms. The expression of TNF-α, IL-1β, and MMP-9 was higher in the adventitial fat of diseased vessels compared with healthy tissues. Finally, adipocytes treated with TNF-α showed enhanced MMP-2, MMP-3, and cathepsin D, which was prevented by telmisartan. Taken together, HFD in mice induced aortic dilatation with up-regulation of matrix degrading and inflammatory pathways similar to those seen in human aortic aneurysmatic tissue. The HFD-induced vascular pathology was reduced by AT1-receptor antagonist telmisartan. © 2017 The Author(s). Published by Portland Press Limited on behalf

  13. 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.

  14. Sodium intake influences hemodynamic and neural responses to angiotensin receptor blockade in rostral ventrolateral medulla.

    PubMed

    DiBona, G F; Jones, S Y

    2001-04-01

    To determine the effects of physiological alterations in endogenous angiotensin II activity on basal renal sympathetic nerve activity (RSNA) and its arterial baroreflex regulation, angiotensin II type 1 receptor antagonists were microinjected into the rostral ventrolateral medulla of anesthetized rats consuming a low, normal, or high sodium diet that were instrumented for simultaneous measurement of arterial pressure and RSNA. Plasma renin activity was increased in rats fed a low sodium diet and decreased in those fed a high sodium diet. Losartan (50, 100, and 200 pmol) decreased heart rate and RSNA (but not mean arterial pressure) dose-dependently; the responses were significantly greater in rats fed a low sodium diet than in those fed a high sodium diet. Candesartan (1, 2, and 10 pmol) decreased mean arterial pressure, heart rate, and RSNA dose-dependently; the responses were significantly greater in rats fed a low sodium diet than in those fed a normal or high sodium diet. [D-Ala(7)]Angiotensin-(1-7) (100, 200, and 1000 pmol) did not affect mean arterial pressure, heart rate, or RSNA in rats fed either a low or a high sodium diet. In rats fed a low sodium diet, candesartan reset the arterial baroreflex control of RSNA to a lower level of arterial pressure, and in rats with congestive heart failure, candesartan increased the arterial baroreflex gain of RSNA. Physiological alterations in the endogenous activity of the renin-angiotensin system influence the bradycardic, vasodepressor, and renal sympathoinhibitory responses to rostral ventrolateral medulla injection of antagonists to angiotensin II type 1 receptors but not to angiotensin-(1-7) receptors.

  15. Pharmacological Blockade of the Chemokine Receptor CCR1 Protects Mice from Systemic Candidiasis of Hematogenous Origin

    PubMed Central

    Albert, Nathaniel D.; Swamydas, Muthulekha; Lee, Chyi-Chia R.; Loetscher, Pius

    2016-01-01

    ABSTRACT Systemic candidiasis is a leading cause of nosocomial bloodstream infection with a high mortality rate despite treatment. Immune-based strategies are needed to improve outcomes. We previously reported that genetic deficiency in the chemokine receptor CCR1 improves survival and ameliorates tissue damage in Candida-infected mice. Here, we found that treatment of immunocompetent Candida-infected mice with the CCR1-selective antagonist BL5923 improves survival, decreases the kidney fungal burden, and protects from renal tissue injury. PMID:27993850

  16. Blockade of N-methyl-D-aspartate Receptors May Protect against Ischemic Damage in the Brain

    NASA Astrophysics Data System (ADS)

    Simon, R. P.; Swan, J. H.; Griffiths, T.; Meldrum, B. S.

    1984-11-01

    In rats ischemia of the forebrain induced by a 30-minute occlusion of the carotid artery, followed by 120 minutes of arterial reperfusion, produced ischemic lesions of selectively vulnerable pyramidal cells in both hippocampi. Focal microinfusion into the dorsal hippocampus of 2-amino-7-phosphonoheptanoic acid, an antagonist of excitation at the N-methyl-d-asparate-preferring receptor, before ischemia was induced protected against the development of ischemic damage. It is proposed that excitatory neurotransmission plays an important role in selective neuronal loss due to cerebral ischemia.

  17. AMP Is an Adenosine A1 Receptor Agonist*

    PubMed Central

    Rittiner, Joseph E.; Korboukh, Ilia; Hull-Ryde, Emily A.; Jin, Jian; Janzen, William P.; Frye, Stephen V.; Zylka, Mark J.

    2012-01-01

    Numerous receptors for ATP, ADP, and adenosine exist; however, it is currently unknown whether a receptor for the related nucleotide adenosine 5′-monophosphate (AMP) exists. Using a novel cell-based assay to visualize adenosine receptor activation in real time, we found that AMP and a non-hydrolyzable AMP analog (deoxyadenosine 5′-monophosphonate, ACP) directly activated the adenosine A1 receptor (A1R). In contrast, AMP only activated the adenosine A2B receptor (A2BR) after hydrolysis to adenosine by ecto-5′-nucleotidase (NT5E, CD73) or prostatic acid phosphatase (PAP, ACPP). Adenosine and AMP were equipotent human A1R agonists in our real-time assay and in a cAMP accumulation assay. ACP also depressed cAMP levels in mouse cortical neurons through activation of endogenous A1R. Non-selective purinergic receptor antagonists (pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid and suramin) did not block adenosine- or AMP-evoked activation. Moreover, mutation of His-251 in the human A1R ligand binding pocket reduced AMP potency without affecting adenosine potency. In contrast, mutation of a different binding pocket residue (His-278) eliminated responses to AMP and to adenosine. Taken together, our study indicates that the physiologically relevant nucleotide AMP is a full agonist of A1R. In addition, our study suggests that some of the physiological effects of AMP may be direct, and not indirect through ectonucleotidases that hydrolyze this nucleotide to adenosine. PMID:22215671

  18. 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.

  19. Differential effects of dopamine and opioid receptor blockade on motivated Coca-Cola drinking behavior and associated changes in brain, skin and muscle temperatures.

    PubMed

    Kiyatkin, E A

    2010-05-05

    Although pharmacological blockade of both dopamine (DA) and opiate receptors has an inhibiting effect on appetitive motivated behaviors, it is still unclear which physiological mechanisms affected by these treatments underlie the behavioral deficit. To clarify this issue, we examined how pharmacological blockade of either DA (SCH23390+eticlopride at 0.2 mg/kg each) or opioid receptors (naloxone 1 mg/kg) affects motor activity and temperature fluctuations in the nucleus accumbens (NAcc), temporal muscle, and facial skin associated with motivated Coca-Cola drinking behavior in rats. In drug-free conditions, presentation of a cup containing 5 ml of Coca-Cola induced locomotor activation and rapid NAcc temperature increases, which both transiently decreased during drinking, and phasically increased again after the cup was emptied. Muscle temperatures followed this pattern, but increases were weaker and more delayed than those in the NAcc. Skin temperature rapidly dropped after cup presentation, remained at low levels during consumption, and slowly restored during post-consumption behavioral activation. By itself, DA receptor blockade induced robust decrease in spontaneous locomotion, moderate increases in brain and muscle temperatures, and a relative increase in skin temperatures, suggesting metabolic activation coupled with adynamia. Following this treatment (approximately 180 min), motor activation to cup presentation and Coca-Cola consumption were absent, but rats showed NAcc and muscle temperature increases following cup presentation comparable to control. Therefore, DA receptor blockade does not affect significantly central and peripheral autonomic responses to appetitive stimuli, but eliminates their behavior-activating effects, thus disrupting appetitive behavior and blocking consumption. Naloxone alone slightly decreased brain and muscle temperatures and increased skin temperatures, pointing at the enhanced heat loss and possible minor inhibition of basal

  20. Differential effects of dopamine and opioid receptor blockade on motivated Coca-Cola drinking behavior and associated changes in brain, skin and muscle temperatures

    PubMed Central

    Kiyatkin, Eugene A.

    2010-01-01

    Although pharmacological blockade of both dopamine (DA) and opiate receptors has an inhibiting effect on appetitive motivated behaviors, it is still unclear which physiological mechanisms affected by these treatments underlie the behavioral deficit. To clarify this issue, we examined how pharmacological blockade of either DA (SCH23390 + eticlopride at 0.2 mg/kg each) or opioid receptors (naloxone 1 mg/kg) affects motor activity and temperature fluctuations in the nucleus acumens (NAcc), temporal muscle, and facial skin associated with motivated Coca-Cola drinking behavior in rats. In drug-free conditions, presentation of a cup containing 5 ml of Coca-Cola induced locomotor activation and rapid NAcc temperature increases, which both transiently decreased during drinking, and phasically increased again after the cup was emptied. Muscle temperatures followed this pattern, but increases were weaker and more delayed than those in the NAcc. Skin temperature rapidly dropped after cup presentation, remained at low levels during consumption, and slowly restored during post-consumption behavioral activation. By itself, DA receptor blockade induced robust decrease in spontaneous locomotion, moderate increases in brain and muscle temperatures, and a relative increase in skin temperatures, suggesting metabolic activation coupled with adynamia. Following this treatment (∼180 min), motor activation to cup presentation and Coca-Cola consumption were absent, but rats showed NAcc and muscle temperature increases following cup presentation comparable to control. Therefore, DA receptor blockade does not affect significantly central and peripheral autonomic responses to appetitive stimuli, but eliminates their behavior-activating effects, thus disrupting appetitive behavior and blocking consumption. Naloxone alone slightly decreased brain and muscle temperatures and increased skin temperatures, pointing at the enhanced heat loss and possible minor inhibition of basal metabolic

  1. Blockade of the interaction of leukotriene b4 with its receptor prevents development of autoimmune uveitis.

    PubMed

    Liao, Tianjiang; Ke, Yan; Shao, Wen-Hai; Haribabu, Bodduluri; Kaplan, Henry J; Sun, Deming; Shao, Hui

    2006-04-01

    To investigate the role of leukotriene B4 (LTB4) and its receptor BLT1 in the pathogenesis of mouse uveitis. Experimental autoimmune uveitis (EAU) was induced in B10RIII mice by immunization of interphotoreceptor retinoid binding protein (IRBP; peptide sequence 161-180) or in C57BL/6 (B6) mice by transfer of activated T cells specific for IRBP1-20. The animals were then treated with and without the BLT1 receptor antagonist, CP105696, at the disease onset after immunization or at day 0 or day 6 after T-cell transfer. EAU was also induced in wild-type B6 (WT) and BLT1-deficient (BLT1-/-) mice by reciprocal transfer of the T cells from B6 to BLT1-deficient mice and vise versa. Clinical signs of inflammation and ocular histology were compared. The chemotactic activity of LTB4 on naïve and IRBP-specific autoreactive T cells as well as effector leukocytes was examined. The treatment of CP105696, greatly reduced the intensity of ongoing disease. IRBP1-20-specific T cells derived from wild-type B6 mice induced only mild uveitis in syngeneic BLT1-deficient mice and that IRBP1-20-specific T cells derived from BLT1-/- mice induced milder disease in wild-type B6 mice than those derived from wild-type B6 mice, suggesting that expression of the LTB4 receptor on both activated autoreactive T cells and effector leukocytes was necessary for ocular inflammation to occur. Consistent with these data, transfer of autoreactive T cells from B6 mice to 5-lipoxygenase-deficient (5-LO-/-) mice, which have a functional defect in LTB4 expression, also failed to induce uveitis in the recipient mice. The results demonstrate a critical role for LTB4 in ocular inflammation and in the development and progression of EAU and suggest a new potential target for therapeutic intervention in this disease.

  2. Effects of 5-HT5A receptor blockade on amnesia or forgetting.

    PubMed

    Aparicio-Nava, L; Márquez-García, L A; Meneses, A

    2018-01-09

    Previously the effects (0.01-3.0 mg/kg) of post-training SB-699551 (a 5-HT 5A receptor antagonist) were reported in the associative learning task of autoshaping, showing that SB-699551 (0.1 mg/kg) decreased lever-press conditioned responses (CR) during short-term (STM; 1.5-h) or (3.0 mg/kg) long-term memory (LTM; 24-h); relative to the vehicle animals. Moreover, as pro-cognitive efficacy of SB-699551 was reported in the ketamine-model of schizophrenia. Hence, firstly aiming improving performance (conditioned response, CR), in this work autoshaping lever-press vs. nose-poke response was compared; secondly, new set of animals were randomly assigned to SB-699551 plus forgetting or amnesia protocols. Results show that the nose-poke operandum reduced inter-individual variance, increased CR and produced a progressive CR until 48-h. After one week of no training/testing sessions (i.e., interruption of 216 h), the forgetting was observed; i.e., the CR% of control-saline group significantly decreased. In contrast, SB-699551 at 0.3 and 3.0 mg/kg prevents forgetting. Additionally, as previously reported the non-competitive NMDA receptor antagonist dizocilpine (0.2 mg/kg) or the non-selective cholinergic antagonist scopolamine (0.3 mg/kg) decreased CR in STM. SB-699551 (0.3 mg/kg) alone also produced amnesia-like effect. Co-administration of SB-699551-dizocilpine or SB-699551-scopolamine reversed the SB-699551 induced-amnesic effects in LTM (24-h). Nose-poke seems to be a reliable operandum. The anti-amnesic and anti-forgetting mechanisms of amnesic SB-699551-dose remain unclear. The present findings are consistent with the notion that low doses of 5-HT 5A receptor antagonists might be useful for reversing memory deficits associated to forgetting and amnesia. Of course, further experiments are necessary. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. 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

  4. Orexin-1 receptor blockade suppresses compulsive-like alcohol drinking in mice

    PubMed Central

    Lei, Kelly; Wegner, Scott A.; Yu, Ji-Hwan; Hopf, F. Woodward

    2016-01-01

    Addiction is promoted by pathological motivation for addictive substances, and, despite extensive efforts, alcohol use disorders (AUDs) continue to extract a very high social, physical, and economic toll. Compulsive drinking of alcohol, where consumption persists even when alcohol is paired with negative consequences, is considered a particular obstacle for treating AUDs. Aversion-resistant alcohol intake in rodents, e.g. where rodents drink even when alcohol is paired with the bitter tastant quinine, has been considered to model some compulsive aspects of human alcohol consumption. However, the critical mechanisms that drive compulsive-like drinking are only beginning to be identified. The neuropeptide orexin has been linked to high motivation for cocaine, preferred foods, and alcohol. Thus, we investigated the role of orexin receptors in compulsive-like alcohol drinking, where C57BL/6 mice had 2-hr daily access to 15% alcohol with or without quinine (100 µM). We found that systemic administration of the widely used selective orexin-1 receptor (OX1R) blocker, SB-334867 (SB), significantly reduced compulsive-like consumption at doses lower than those reported to reduce quinine-free alcohol intake. The dose of 3-mg/kg SB, in particular, suppressed only compulsive-like drinking. Furthermore, SB did not reduce concurrent water intake during the alcohol drinking sessions, and did not alter saccharin+quinine consumption. In addition, the OX2R antagonist TCS-OX2-29 (3 or 10 mg/kg) did not alter intake of alcohol with or without quinine. Together, our results suggest that OX1R signaling is particularly important for promoting compulsive-like alcohol drinking, and that OX1Rs might represent a novel therapy to counteract compulsive aspects of human AUDs. PMID:27523303

  5. Caffeinol at the receptor level; Anti-ischemic effect of NMDA receptor blockade is potentiated by caffeine

    PubMed Central

    Zhao, Xiurong; Strong, Roger; Piriyawat, Paisith; Palusinski, Robert; Grotta, James C.; Aronowski, Jaroslaw

    2010-01-01

    Background and Purpose Although caffeinol (combination of low dose of caffeine and ethanol) was shown to robustly reduce stroke damage in experimental models and is now in clinical evaluation for treatment of ischemic stroke, little is known about the potential mechanism of its action. Methods We have used an in vivo excitotoxicity model based on intracortical infusion of NMDA and model of reversible focal ischemia to demonstrate NMDA receptor inhibition as one potential mechanism of Caffeinol anti-ischemic activity. Results Caffeinol reduced the size of excitotoxic lesion and substitution of ethanol in Caffeinol with CNS-1102 and MK-801, but not with MgSO4, produced treatment with strong synergistic effect that was at least as robust in reducing ischemic damage as Caffeinol. This NMDA receptor antagonist and caffeine combination showed long window of opportunity, activity in spontaneously hypertensive rats, and unlike Caffeinol was fully effective in animals chronically pre-treated with ethanol. Conclusions Our study suggests that anti-excitotoxic properties may underlie some of the anti-ischemic effect of Caffeinol. This study provides strong evidence that the anti-ischemic effect of NMDA receptor blockers in general can be dramatically augmented by caffeine, thus opening a possibility for new utilization of NMDA-based pharmacology in the treatment of stroke. PMID:20044532

  6. 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.

  7. Blood pressure-independent renoprotection in diabetic rats treated with AT1 receptor-neprilysin inhibition compared with AT1 receptor blockade alone.

    PubMed

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

    2016-07-01

    ARNI [dual AT1 (angiotensin II type 1) receptor-neprilysin inhibition] exerts beneficial effects on blood pressure and kidney function in heart failure, compared with ARB (AT1 receptor blockade) alone. We hypothesized that ARNI improves cardiac and kidney parameters in diabetic TGR(mREN2)27 rats, an angiotensin II-dependent hypertension model. Rats were made diabetic with streptozotocin for 5 or 12 weeks. In the final 3 weeks, rats were treated with vehicle, irbesartan (ARB) or irbesartan+thiorphan (ARNI). Blood pressure, measured by telemetry in the 5-week group, was lowered identically by ARB and ARNI. The heart weight/tibia length ratio in 12-week diabetic animals was lower after ARNI compared with after ARB. Proteinuria and albuminuria were observed from 8 weeks of diabetes onwards. ARNI reduced proteinuria more strongly than ARB, and a similar trend was seen for albuminuria. Kidneys of ARNI-treated animals showed less severe segmental glomerulosclerosis than those of ARB-treated animals. After 12 weeks, no differences between ARNI- and ARB-treated animals were found regarding diuresis, natriuresis, plasma endothelin-1, vascular reactivity (acetylcholine response) or kidney sodium transporters. Only ARNI-treated rats displayed endothelin type B receptor-mediated vasodilation. In conclusion, ARNI reduces proteinuria, glomerulosclerosis and heart weight in diabetic TGR(mREN2)27 rats more strongly than does ARB, and this occurs independently of blood pressure. © 2016 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

  8. Buspirone Counteracts MK-801-Induced Schizophrenia-Like Phenotypes through Dopamine D3 Receptor Blockade

    PubMed Central

    Torrisi, Sebastiano Alfio; Salomone, Salvatore; Geraci, Federica; Caraci, Filippo; Bucolo, Claudio; Drago, Filippo; Leggio, Gian Marco

    2017-01-01

    Background: Several efforts have been made to develop effective antipsychotic drugs. Currently, available antipsychotics are effective on positive symptoms, less on negative symptoms, but not on cognitive impairment, a clinically relevant dimension of schizophrenia. Drug repurposing offers great advantages over the long-lasting, risky and expensive, de novo drug discovery strategy. To our knowledge, the possible antipsychotic properties of buspirone, an azapirone anxiolytic drug marketed in 1986 as serotonin 5-HT1A receptor (5-HT1AR) partial agonist, have not been extensively investigated despite its intriguing pharmacodynamic profile, which includes dopamine D3 (D3R) and D4 receptor (D4R) antagonist activity. Multiple lines of evidence point to D3R as a valid therapeutic target for the treatment of several neuropsychiatric disorders including schizophrenia. In the present study, we tested the hypothesis that buspirone, behaving as dopamine D3R antagonist, may have antipsychotic-like activity. Materials and Methods: Effects of acute administration of buspirone was assessed on a wide-range of schizophrenia-relevant abnormalities induced by a single administration of the non-competitive NMDAR antagonist MK-801, in both wild-type mice (WT) and D3R-null mutant mice (D3R-/-). Results: Buspirone (3 mg⋅kg-1, i.p.) was devoid of cataleptogenic activity in itself, but resulted effective in counteracting disruption of prepulse inhibition (PPI), hyperlocomotion and deficit of temporal order recognition memory (TOR) induced by MK-801 (0.1 mg⋅kg-1, i.p.) in WT mice. Conversely, in D3R-/- mice, buspirone was ineffective in preventing MK-801-induced TOR deficit and it was only partially effective in blocking MK-801-stimulated hyperlocomotion. Conclusion: Taken together, these results indicate, for the first time, that buspirone, might be a potential therapeutic medication for the treatment of schizophrenia. In particular, buspirone, through its D3R antagonist activity, may be

  9. 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...

  10. The effect of hippocampal NMDA receptor blockade by MK-801 on cued fear extinction.

    PubMed

    Zhang, Bo; Li, Chuan-Yu; Wang, Xiu-Song

    2017-08-14

    Extinction of conditioned fear has been suggested to be a new form of learning instead of erasure of what was originally learned, and the process is NMDA (N-methyl d-aspartate) receptor (NMDAR) dependent. Most of studies have so far revealed the important roles of NMDARs in the amygdala and medial prefrontal cortex (mPFC) in cued fear extinction. Although the ventral hippocampus has intimately reciprocal connections with the amygdala and mPFC, the role of its NMDARs in cued fear extinction remains unclear. The present experiment explored the issue by bilateral pre-extinction microinjection of the noncompetitive NMDAR antagonist MK-801 into the ventral hippocampus. Four groups of rats were given habituation, tone cued fear conditioning, fear extinction training and extinction test. Prior to extinction training, rats received bilateral infusions of either MK-801 (1.5, 3, or 6μg/0.5μl) or saline. Our results showed that MK-801 reduced freezing on the first trial of extinction training with no impact on within-session acquisition of extinction, and that the lower doses of MK-801 resulted in increased freezing on the extinction retrieval test. These findings suggest that ventral hippocampal NMDARs are necessary for the consolidation of tone cued fear extinction. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Estrous cycle and food availability affect feeding induced by amygdala 5-HT receptor blockade.

    PubMed

    Parker, Graham C; Bishop, Christopher; Coscina, Donald V

    2002-04-01

    We have recently reported that bilateral infusions of the 5-HT receptor antagonist metergoline (MET) into the posterior basolateral amygdala (pBLA) elicit feeding in female rats tested at mid-light cycle. The present study was performed to determine whether (1) testing at two different phases of the estrous cycle, and/or (2) the palatability of the food might modify this effect. Subjects were 18 adult females with bilateral pBLA cannulae. Following familiarization with Froot Loops cereal, a within-subjects design tested all animals for 1- and 2-h food intake under 2 Drug (0.3 nmol MET vs. Vehicle), 2 Estrous Cycle (diestrus vs. estrus) and 2 Food (lab chow vs. Froot Loops) conditions. Rats weighed more at diestrus than at proestrus (P<.05) or estrus (P<.005). Multivariate analyses of variance (MANOVAs) revealed a preference for Froot Loops over lab chow (P<.0001). MET increased feeding regardless of food type (P<.0001). Rats ate more Froot Loops (P<.01), but not lab chow, at diestrus vs. estrus. A three-way interaction (P<.05) showed rats ate more during the first hour in estrus than in diestrus to lab chow but not Froot Loops. These data suggest pBLA MET differentially affects feeding over the estrous cycle depending on the palatability of food available.

  12. EFFECT OF AT1 RECEPTOR BLOCKADE ON INTERMITTENT HYPOXIA-INDUCED ENDOTHELIAL DYSFUNCTION

    PubMed Central

    Marcus, Noah J.; Philippi, Nathan R.; Bird, Cynthia E.; Li, Yu-Long; Schultz, Harold D.; Morgan, Barbara J.

    2012-01-01

    Chronic intermittent hypoxia (CIH) raises arterial pressure, impairs vasodilator responsiveness, and increases circulating angiotensin II (Ang II); however, the role of Ang II in CIH-induced vascular dysfunction is unknown. Rats were exposed to CIH or room air (NORM), and a subset of these animals was treated with losartan (Los) during the exposure period. After 28 days, vasodilatory responses to acetylcholine or nitroprusside were measured in isolated gracilis arteries. Superoxide levels and Ang II receptor protein expression were measured in saphenous arteries. After 28 days, arterial pressure was increased and acetylcholine-induced vasodilation was blunted in CIH vs. NORM, and this was prevented by Los. Responses to nitroprusside and superoxide levels did not differ between CIH and NORM. Expression of AT2R was decreased and the AT1R:AT2R ratio was increased in CIH vs. NORM, but this was unaffected by Los. These results indicate that the blood pressure elevation and endothelial dysfunction associated with CIH is dependent, at least in part, on RAS signaling. PMID:22728949

  13. 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

  14. 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.

  15. 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

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

    SciTech Connect

    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

  17. Androgen receptor splice variants circumvent AR blockade by microtubule-targeting agents

    PubMed Central

    Zhang, Guanyi; Liu, Xichun; Li, Jianzhuo; Ledet, Elisa; Alvarez, Xavier; Qi, Yanfeng; Fu, Xueqi; Sartor, Oliver; Dong, Yan; Zhang, Haitao

    2015-01-01

    Docetaxel-based chemotherapy is established as a first-line treatment and standard of care for patients with metastatic castration-resistant prostate cancer. However, half of the patients do not respond to treatment and those do respond eventually become refractory. A better understanding of the resistance mechanisms to taxane chemotherapy is both urgent and clinical significant, as taxanes (docetaxel and cabazitaxel) are being used in various clinical settings. Sustained signaling through the androgen receptor (AR) has been established as a hallmark of CRPC. Recently, splicing variants of AR (AR-Vs) that lack the ligand-binding domain (LBD) have been identified. These variants are constitutively active and drive prostate cancer growth in a castration-resistant manner. In taxane-resistant cell lines, we found the expression of a major variant, AR-V7, was upregulated. Furthermore, ectopic expression of two clinically relevant AR-Vs (AR-V7 and ARV567es), but not the full-length AR (AR-FL), reduced the sensitivities to taxanes in LNCaP cells. Treatment with taxanes inhibited the transcriptional activity of AR-FL, but not those of AR-Vs. This could be explained, at least in part, due to the inability of taxanes to block the nuclear translocation of AR-Vs. Through a series of deletion constructs, the microtubule-binding activity was mapped to the LBD of AR. Finally, taxane-induced cytoplasm sequestration of AR-FL was alleviated when AR-Vs were present. These findings provide evidence that constitutively active AR-Vs maintain the AR signaling axis by evading the inhibitory effects of microtubule-targeting agents, suggesting that these AR-Vs play a role in resistance to taxane chemotherapy. PMID:26160840

  18. Optimization for the blockade of epidermal growth factor receptor signaling for therapy of human pancreatic carcinoma.

    PubMed

    Solorzano, C C; Baker, C H; Tsan, R; Traxler, P; Cohen, P; Buchdunger, E; Killion, J J; Fidler, I J

    2001-08-01

    We determined the optimal administration schedule of a novel epidermal growth factor receptor (EGFR) protein tyrosine kinase inhibitor (PKI), PKI 166 (4-(R)-phenethylamino-6-(hydroxyl)phenyl-7H-pyrrolo[2.3-d]-pyrimidine), alone or in combination with gemcitabine (administered i.p.) for therapy of L3.6pl human pancreatic carcinoma growing in the pancreas of nude mice. Seven days after orthotopic implantation of L3.6pl cells, the mice received daily oral doses of PKI 166. PKI 166 therapy significantly inhibited phosphorylation of the EGFR without affecting EGFR expression. EGFR phosphorylation was restored 72 h after cessation of therapy. Seven days after orthotopic injection of L3.6pl cells, groups of mice received daily or thrice weekly oral doses of PKI 166 alone or in combination with gemcitabine. Treatment with PKI 166 (daily), PKI 166 (3 times/week), or gemcitabine alone produced a 72%, 69%, or 70% reduction in the volume of pancreatic tumors in mice, respectively. Daily oral PKI 166 or thrice weekly oral PKI 166 in combination with injected gemcitabine produced 97% and 95% decreases in volume of pancreatic cancers and significant inhibition of lymph node and liver metastasis. Daily oral PKI 166 produced a 20% decrease in body weight, whereas treatment 3 times/week did not. Decreased microvessel density, decreased proliferating cell nuclear antigen staining, and increased tumor cell and endothelial cell apoptosis correlated with therapeutic success. Collectively, our results demonstrate that three weekly oral administrations of an EGFR tyrosine kinase inhibitor in combination with gemcitabine are sufficient to significantly inhibit primary and metastatic human pancreatic carcinoma.

  19. Effect of oxytocin receptor blockade on appetite for sugar is modified by social context.

    PubMed

    Olszewski, Pawel K; Allen, Kerry; Levine, Allen S

    2015-03-01

    Research on oxytocin (OT) has yielded two seemingly unrelated sets of discoveries: OT has prosocial effects, and it elicits termination of feeding, especially of food rich in carbohydrates. Here we investigated whether OT's involvement in food intake is affected by the social context in mice, with particular focus on the role of dominance. We used two approaches: injections and gene expression analysis. We housed two males per cage and determined a dominant one. Then we injected a blood-brain barrier penetrant OT receptor antagonist L-368,899 in either dominant or subordinate animals and gave them 10-min access to a sucrose solution in the apparatus in which social exposure was modified and it ranged from none to unrestricted contact. L-368,899 increased the amount of consumed sugar in dominant mice regardless of whether these animals had access to sucrose in the non-social or social contexts (olfactory-derived or partial social exposure). The antagonist also increased the proportion of time that dominant mice spent drinking the sweet solution in the paradigm in which both mice had to share a single source of sucrose. L-368,899-treated subordinate mice consumed more sucrose solution than saline controls only when the environment in which sugar was presented was devoid of social cues related to the dominant animal. Finally, we investigated whether hypothalamic OT gene expression differs between dominant and subordinate mice consuming sugar and found OT mRNA levels to be higher in dominant mice. We conclude that social context and dominance affect OT's effect on appetite for sucrose. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Blockade of protease-activated receptor-4 (PAR4) provides robust antithrombotic activity with low bleeding.

    PubMed

    Wong, Pancras C; Seiffert, Dietmar; Bird, J Eileen; Watson, Carol A; Bostwick, Jeffrey S; Giancarli, Mary; Allegretto, Nick; Hua, Ji; Harden, David; Guay, Jocelyne; Callejo, Mario; Miller, Michael M; Lawrence, R Michael; Banville, Jacques; Guy, Julia; Maxwell, Brad D; Priestley, E Scott; Marinier, Anne; Wexler, Ruth R; Bouvier, Michel; Gordon, David A; Schumacher, William A; Yang, Jing

    2017-01-04

    Antiplatelet agents are proven efficacious treatments for cardiovascular and cerebrovascular diseases. However, the existing drugs are compromised by unwanted and sometimes life-threatening bleeding that limits drug usage or dosage. There is a substantial unmet medical need for an antiplatelet drug with strong efficacy and low bleeding risk. Thrombin is a potent platelet agonist that directly induces platelet activation via the G protein (heterotrimeric guanine nucleotide-binding protein)-coupled protease-activated receptors PAR1 and PAR4. A PAR1 antagonist is approved for clinical use, but its use is limited by a substantial bleeding risk. Conversely, the potential of PAR4 as an antiplatelet target has not been well characterized. Using anti-PAR4 antibodies, we demonstrated a low bleeding risk and an effective antithrombotic profile with PAR4 inhibition in guinea pigs. Subsequently, high-throughput screening and an extensive medicinal chemistry effort resulted in the discovery of BMS-986120, an orally active, selective, and reversible PAR4 antagonist. In a cynomolgus monkey arterial thrombosis model, BMS-986120 demonstrated potent and highly efficacious antithrombotic activity. BMS-986120 also exhibited a low bleeding liability and a markedly wider therapeutic window compared to the standard antiplatelet agent clopidogrel tested in the same nonhuman primate model. These preclinical findings define the biological role of PAR4 in mediating platelet aggregation. In addition, they indicate that targeting PAR4 is an attractive antiplatelet strategy with the potential to treat patients at a high risk of atherothrombosis with superior safety compared with the current standard of care. Copyright © 2017, American Association for the Advancement of Science.

  1. Enhanced inhibitory control by neuropeptide Y Y5 receptor blockade in rats.

    PubMed

    Bari, A; Dec, A; Lee, A W; Lee, J; Song, D; Dale, E; Peterson, J; Zorn, S; Huang, X; Campbell, B; Robbins, T W; West, A R

    2015-03-01

    The neuropeptide Y (NPY) system acts in synergy with the classic neurotransmitters to regulate a large variety of functions including autonomic, affective, and cognitive processes. Research on the effects of NPY in the central nervous system has focused on food intake control and affective processes, but growing evidence of NPY involvement in attention-deficit/hyperactivity disorder (ADHD) and other psychiatric conditions motivated the present study. We tested the effects of the novel and highly selective NPY Y5 receptor antagonist Lu AE00654 on impulsivity and the underlying cortico-striatal circuitry in rats to further explore the possible involvement of the NPY system in pathologies characterized by inattention and impulsive behavior. A low dose of Lu AE00654 (0.03 mg/kg) selectively facilitated response inhibition as measured by the stop-signal task, whereas no effects were found at higher doses (0.3 and 3 mg/kg). Systemic administration of Lu AE00654 also enhanced the inhibitory influence of the dorsal frontal cortex on neurons in the caudate-putamen, this fronto-striatal circuitry being implicated in the executive control of behavior. Finally, by locally injecting a Y5 agonist, we observed reciprocal activation between dorsal frontal cortex and caudate-putamen neurons. Importantly, the effects of the Y5 agonist were attenuated by pretreatment with Lu AE00654, confirming the presence of Y5 binding sites modulating functional interactions within frontal-subcortical circuits. These results suggest that the NPY system modulates inhibitory neurotransmission in brain areas important for impulse control, and may be relevant for the treatment of pathologies such as ADHD and drug abuse.

  2. Blockade of Nogo Receptor Ligands Promotes Functional Regeneration of Sensory Axons After Dorsal Root Crush

    PubMed Central

    Harvey, Pamela A.; Lee, Daniel H.S.; Qian, Fang; Weinreb, Paul H.; Frank, Eric

    2010-01-01

    A major impediment for regeneration of axons within the central nervous system is the presence of multiple inhibitory factors associated with myelin. Three of these factors bind to the Nogo receptor, NgR, which is expressed on axons. Administration of exogenous blockers of NgR or NgR ligands promotes the regeneration of descending axonal projections after spinal cord hemisection. A more detailed analysis of CNS regeneration can be made by examining the growth of specific classes of sensory axons into the spinal cord after dorsal root crush injury . In this study, we assessed whether administration of a soluble peptide fragment of the NgR that binds to and blocks all three NgR ligands can promote regeneration after brachial dorsal root crush in adult rats. Intraventricular infusion of sNgR for one month results in extensive regrowth of myelinated sensory axons into the white and gray matter of the dorsal spinal cord, but unmyelinated sensory afferents do not regenerate. In concert with the anatomical growth of sensory axons into the cord, there is a gradual restoration of synaptic function in the denervated region, as revealed by extracellular microelectrode recordings from the spinal gray matter in response to stimulation of peripheral nerves. These positive synaptic responses are correlated with substantial improvements in use of the forelimb, as assessed by paw preference, paw withdrawal to tactile stimuli and the ability to grasp. These results suggest that sNgR may be a potential therapy for restoring sensory function following injuries to sensory roots. PMID:19439606

  3. Maslinic acid ameliorates NMDA receptor blockade-induced schizophrenia-like behaviors in mice.

    PubMed

    Jeon, Se Jin; Kim, Eunji; Lee, Jin Su; Oh, Hee Kyong; Zhang, Jiabao; Kwon, Yubeen; Jang, Dae Sik; Ryu, Jong Hoon

    2017-11-01

    Schizophrenia is a chronic psychotic disorder characterized by positive, negative, and cognitive symptoms. Primary treatments for schizophrenia relieve the positive symptoms but are less effective against the negative and cognitive symptoms. In the present study, we investigated whether maslinic acid, isolated from Syzygium aromaticum (clove), can ameliorate schizophrenia-like behaviors in mice induced by MK-801, an N-methyl-d-aspartate (NMDA) receptor antagonist. After maslinic acid treatment in the MK-801 model, we examined the behavioral alteration and signaling pathways in the prefrontal cortex. Mice were treated with maslinic acid (30 mg/kg), and their behaviors were evaluated through an array of behavioral tests. The effects of maslinic acid were also examined in the signaling pathways in the prefrontal cortex. A single administration of maslinic acid blocked the MK-801-induced hyperlocomotion and reversed the MK-801-induced sensorimotor gating deficit in the acoustic startle response test. In the social novelty preference test, maslinic acid ameliorated the social behavior deficits induced by MK-801. The MK-801-induced attention and recognition memory impairments were also alleviated by a single administration of maslinic acid. Furthermore, maslinic acid normalized the phosphorylation levels of Akt-GSK-3β and ERK-CREB in the prefrontal cortex. Overall, maslinic acid ameliorated the schizophrenia-like symptoms induced by MK-801, and these effects may be partly mediated through Akt-GSK-3β and ERK-CREB activation. These findings suggest that maslinic acid could be a candidate for the treatment of several symptoms of schizophrenia, including positive symptoms, sensorimotor gating disruption, social interaction deficits, and cognitive impairments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Cortisol receptor blockade and seawater adaptation in the euryhaline teleost Fundulus heteroclitus

    USGS Publications Warehouse

    Marshall, W.S.; Cozzi, R.R.F.; Pelis, Ryan M.; McCormick, S.D.

    2005-01-01

    To examine the role of cortisol in seawater osmoregulation in a euryhaline teleost, adult killifish were acclimated to brackish water (10???) and RU486 or vehicle was administered orally in peanut oil daily for five days at low (40 mg.kg-1) or high dose (200 mg.kg-1). Fish were transferred to 1.5 x seawater (45???) or to brackish water (control) and sampled at 24 h and 48 h after transfer, when Cl- secretion is upregulated. At 24 h, opercular membrane Cl- secretion rate, as Isc, was increased only in the high dose RU486 group. Stimulation of membranes by 3-isobutyl-1-methylxanthine and cAMP increased Isc in vehicle treated controls but those from RU486-treated animals were unchanged and membranes from brackish water animals showed a decrease in Isc. At 48 h, Isc increased and transepithelial resistance decreased in vehicle and RU486 groups, compared to brackish water controls. Plasma cortisol increased in all groups transferred to high salinity, compared to brackish water controls. RU486 treated animals had higher cortisol levels compared to vehicle controls. Vehicle treated controls had lower cortisol levels than untreated or RU486 treated animals, higher stimulation of Isc, and lower hematocrit at 24 h, beneficial effects attributed to increased caloric intake from the peanut oil vehicle. Chloride cell density was significantly increased in the high dose RU486 group at 48 hours, yet Isc was unchanged, suggesting a decrease in Cl- secretion per cell. Thus cortisol enhances NaCl secretion capacity in chloride cells, likely via glucocorticoid type receptors. ?? 2005 Wiley-Liss, Inc.

  5. 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.

  6. 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.

  7. Adenosine A2A receptor blockade attenuates spatial memory deficit and extent of demyelination areas in lyolecithin-induced demyelination model.

    PubMed

    Akbari, Atefeh; Khalili-Fomeshi, Mohsen; Ashrafpour, Manouchehr; Moghadamnia, Ali Akbar; Ghasemi-Kasman, Maryam

    2018-05-03

    In recent years, inactivation of A 2A adenosine receptors has been emerged as a novel strategy for treatment of several neurodegenerative diseases. Although numerous studies have shown the beneficial effects of A 2A receptors blockade on spatial memory, the impacts of selective adenosine A 2A receptors on memory performance has not yet been examined in the context of demyelination. In the present study, we evaluated the effect of A 2A receptor antagonist SCH58261 on spatial memory and myelination in an experimental model of focal demyelination in rat fimbria. Demyelination was induced by local injection of lysolecithin (LPC) 1% (2 μl) into the hippocampus fimbria. SCH58261 (20 μg/0.5 μl or 40 μg/0.5 μl) was daily injected intracerebroventricularly (i.c.v.) for 10 days post LPC injection. The Morris water maze test was used to assess the spatial learning and memory on day 6 post lesion. Myelin staining and immunostaining against astrocytes/microglia were carried out 10 days post LPC injection. The administration of adenosine A 2A receptor antagonist prevented the spatial memory impairment in LPC receiving animals. Myelin staining revealed that application of SCH58261 reduces the extent of demyelination areas in the fimbria. Furthermore, the level of astrocytes and microglia activation was attenuated following administration of A 2A receptor antagonist. Collectively, the results of this study suggest that A 2A receptor blockade can improve the spatial memory and protect myelin sheath, which might be considered as a novel therapeutic approach for multiple sclerosis disease. Copyright © 2017. Published by Elsevier Inc.

  8. Intrinsic A(1) adenosine receptor activation during ischemia or reperfusion improves recovery in mouse hearts.

    PubMed

    Peart, J; Headrick, J P

    2000-11-01

    We assessed the role of A(1) adenosine receptor (A(1)AR) activation by endogenous adenosine in the modulation of ischemic contracture and postischemic recovery in Langendorff-perfused mouse hearts subjected to 20 min of total ischemia and 30 min of reperfusion. In control hearts, the rate-pressure product (RPP) and first derivative of pressure development over time (+dP/dt) recovered to 57 +/- 3 and 58 +/- 3% of preischemia, respectively. Diastolic pressure remained elevated at 20 +/- 2 mmHg (compared with 3 +/- 1 mmHg preischemia). Interstitial adenosine, assessed by microdialysis, rose from approximately 0.3 to 1.9 microM during ischemia compared with approximately 15 microM in rat heart. Nonetheless, these levels will near maximally activate A(1)ARs on the basis of effects of exogenous adenosine and 2-chloroadenosine. Neither A(1)AR blockade with 200 nM 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) during the ischemic period alone nor A(1)AR activation with 50 nM N(6)-cyclopentyladenosine altered rapidity or extent of ischemic contracture. However, ischemic DPCPX treatment significantly depressed postischemic recovery of RPP and +dP/dt (44 +/- 3 and 40 +/- 4% of preischemia, respectively). DPCPX treatment during the reperfusion period alone also reduced recovery of RPP and +dP/dt (to 44 +/- 2 and 47 +/- 2% of preischemia, respectively). These data indicate that 1) interstitial adenosine is lower in mouse versus rat myocardium during ischemia, 2) A(1)AR activation by endogenous adenosine or exogenous agonists does not modify ischemic contracture in murine myocardium, 3) A(1)AR activation by endogenous adenosine during ischemia attenuates postischemic stunning, and 4) A(1)AR activation by endogenous adenosine during the reperfusion period also improves postischemic contractile recovery.

  9. Beneficial Effects of Combined AT1 Receptor/Neprilysin Inhibition (ARNI) Versus AT1 Receptor Blockade Alone in the Diabetic Eye.

    PubMed

    Prasad, Tuhina; Roksnoer, Lodi C W; Zhu, Ping; Verma, Amrisha; Li, Yiming; Batenburg, Wendy W; de Vries, René; Danser, A H Jan; Li, Qiuhong

    2016-12-01

    Dysfunction of the renin-angiotensin system (RAS) contributes to pathogenesis of diabetic retinopathy (DR). Yet RAS blockers have only limited beneficial effects on progression of DR in clinical trials. The natriuretic peptide system offsets RAS, so that enhancing the activity of this system on top of RAS blockade might be beneficial. Neprilysin has an important role in the degradation of natriuretic peptides. Therefore, we hypothesize that dual angiotensin receptor-neprilysin inhibition (ARNI) may outperform angiotensin receptor blocker (ARB) in protection against DR. We tested this hypothesis in streptozotocin-induced diabetic transgenic (mRen2)27 rats. Adult male diabetic (mRen2)27 rats were followed for 5 or 12 weeks. Treatment with vehicle, irbesartan (ARB), or ARB combined with the neprilysin inhibitor thiorphan (irbesartan+thiorphan [ARNI]) occurred during the final 3 weeks. Retinal cell death, gliosis, and capillary loss were evaluated. Real-time polymerase chain reaction (RT-PCR) analyses were performed to quantify the retinal level of inflammatory cell markers. Both ARB- and ARNI-treated groups showed similarly reduced retinal apoptotic cell death, gliosis, and capillary loss compared to the vehicle-treated group in the 5-week study. Treatment with ARNI reduced the expression of inflammatory markers more than ARB treatment in the 5-week study. In the 12-week study, ARNI treatment showed significantly more reduction in apoptotic cell death (51% vs. 25% reduction), and capillary loss (68% vs. 43% reduction) than ARB treatment. Treatment with ARNI provides better protection against DR in diabetic (mRen2)27 transgenic rats, compared to ARB alone. This approach may be a promising treatment option for patients with DR.

  10. Renal effects of the novel selective adenosine A1 receptor blocker SLV329 in experimental liver cirrhosis in rats.

    PubMed

    Hocher, Berthold; Heiden, Susi; von Websky, Karoline; Arafat, Ayman M; Rahnenführer, Jan; Alter, Markus; Kalk, Philipp; Ziegler, Dieter; Fischer, Yvan; Pfab, Thiemo

    2011-03-10

    Liver cirrhosis is often complicated by an impaired renal excretion of water and sodium. Diuretics tend to further deteriorate renal function. It is unknown whether chronic selective adenosine A(1) receptor blockade, via inhibition of the hepatorenal reflex and the tubuloglomerular feedback, might exert diuretic and natriuretic effects without a reduction of the glomerular filtration rate. In healthy animals intravenous treatment with the novel A(1) receptor antagonist SLV329 resulted in a strong dose-dependent diuretic (up to 3.4-fold) and natriuretic (up to 13.5-fold) effect without affecting creatinine clearance. Male Wistar rats with thioacetamide-induced liver cirrhosis received SLV329, vehicle or furosemide for 12 weeks. The creatinine clearance of cirrhotic animals decreased significantly (-36.5%, p<0.05), especially in those receiving furosemide (-41.9%, p<0.01). SLV329 was able to prevent this decline of creatinine clearance. Mortality was significantly lower in cirrhotic animals treated with SLV329 in comparison to animals treated with furosemide (17% vs. 54%, p<0.05). SLV329 did not relevantly influence the degree of liver fibrosis, kidney histology or expression of hepatic or renal adenosine receptors. In conclusion, chronic treatment with SLV329 prevented the decrease of creatinine clearance in a rat model of liver cirrhosis. Further studies will have to establish whether adenosine A(1) receptor antagonists are clinically beneficial at different stages of liver cirrhosis.

  11. 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.

  12. 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

  13. 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.

  14. Lymphotoxin-beta receptor blockade reduces CXCL13 in lacrimal glands and improves corneal integrity in the NOD model of Sjögren's syndrome

    PubMed Central

    2011-01-01

    Introduction In Sjögren's syndrome, keratoconjunctivitis sicca (dry eye) is associated with infiltration of lacrimal glands by leukocytes and consequent losses of tear-fluid production and the integrity of the ocular surface. We investigated the effect of blockade of the lymphotoxin-beta receptor (LTBR) pathway on lacrimal-gland pathology in the NOD mouse model of Sjögren's syndrome. Methods Male NOD mice were treated for up to ten weeks with an antagonist, LTBR-Ig, or control mouse antibody MOPC-21. Extra-orbital lacrimal glands were analyzed by immunohistochemistry for high endothelial venules (HEV), by Affymetrix gene-array analysis and real-time PCR for differential gene expression, and by ELISA for CXCL13 protein. Leukocytes from lacrimal glands were analyzed by flow-cytometry. Tear-fluid secretion-rates were measured and the integrity of the ocular surface was scored using slit-lamp microscopy and fluorescein isothiocyanate (FITC) staining. The chemokine CXCL13 was measured by ELISA in sera from Sjögren's syndrome patients (n = 27) and healthy controls (n = 30). Statistical analysis was by the two-tailed, unpaired T-test, or the Mann-Whitney-test for ocular integrity scores. Results LTBR blockade for eight weeks reduced B-cell accumulation (approximately 5-fold), eliminated HEV in lacrimal glands, and reduced the entry rate of lymphocytes into lacrimal glands. Affymetrix-chip analysis revealed numerous changes in mRNA expression due to LTBR blockade, including reduction of homeostatic chemokine expression. The reduction of CXCL13, CCL21, CCL19 mRNA and the HEV-associated gene GLYCAM-1 was confirmed by PCR analysis. CXCL13 protein increased with disease progression in lacrimal-gland homogenates, but after LTBR blockade for 8 weeks, CXCL13 was reduced approximately 6-fold to 8.4 pg/mg (+/- 2.7) from 51 pg/mg (+/-5.3) in lacrimal glands of 16 week old control mice. Mice given LTBR blockade exhibited an approximately two-fold greater tear-fluid secretion than

  15. 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.

  16. 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.

  17. Blockade of dopamine D1-family receptors attenuates the mania-like hyperactive, risk-preferring, and high motivation behavioral profile of mice with low dopamine transporter levels.

    PubMed

    Milienne-Petiot, Morgane; Groenink, Lucianne; Minassian, Arpi; Young, Jared W

    2017-10-01

    Patients with bipolar disorder mania exhibit poor cognition, impulsivity, risk-taking, and goal-directed activity that negatively impact their quality of life. To date, existing treatments for bipolar disorder do not adequately remediate cognitive dysfunction. Reducing dopamine transporter expression recreates many bipolar disorder mania-relevant behaviors (i.e. hyperactivity and risk-taking). The current study investigated whether dopamine D 1 -family receptor blockade would attenuate the risk-taking, hypermotivation, and hyperactivity of dopamine transporter knockdown mice. Dopamine transporter knockdown and wild-type littermate mice were tested in mouse versions of the Iowa Gambling Task (risk-taking), Progressive Ratio Breakpoint Test (effortful motivation), and Behavioral Pattern Monitor (activity). Prior to testing, the mice were treated with the dopamine D 1 -family receptor antagonist SCH 23390 hydrochloride (0.03, 0.1, or 0.3 mg/kg), or vehicle. Dopamine transporter knockdown mice exhibited hyperactivity and hyperexploration, hypermotivation, and risk-taking preference compared with wild-type littermates. SCH 23390 hydrochloride treatment decreased premature responding in dopamine transporter knockdown mice and attenuated their hypermotivation. SCH 23390 hydrochloride flattened the safe/risk preference, while reducing activity and exploratory levels of both genotypes similarly. Dopamine transporter knockdown mice exhibited mania-relevant behavior compared to wild-type mice. Systemic dopamine D 1 -family receptor antagonism attenuated these behaviors in dopamine transporter knockdown, but not all effects were specific to only the knockdown mice. The normalization of behavior via blockade of dopamine D 1 -family receptors supports the hypothesis that D 1 and/or D 5 receptors could contribute to the mania-relevant behaviors of dopamine transporter knockdown mice.

  18. BLOCKADE OF NERVE GROWTH FACTOR (NGF) RECEPTOR TRKA ATTENUATES DIESEL EXHAUST PARTICULATE MATTER (DEP) ENHANCEMENT OF ALLERGIC INFLAMMATION

    EPA Science Inventory


    Recent studies have shown that asthmatics have increased levels of the neurotrophin, NGF, in their lungs. In addition, antibody blockade of NGF in mice attenuates airway resistance associated with allergic airway responses. DEP has been linked to asthma exacerbation in many c...

  19. 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

  20. 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.

  1. [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.

  2. 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

  3. 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.

  4. Colony stimulating factor 1 receptor blockade improves the efficacy of chemotherapy against human neuroblastoma in the absence of T lymphocytes.

    PubMed

    Webb, Matthew W; Sun, Jianping; Sheard, Michael A; Liu, Wei-Yao; Wu, Hong-Wei; Jackson, Jeremy R; Malvar, Jemily; Sposto, Richard; Daniel, Dylan; Seeger, Robert C

    2018-04-17

    Tumor-associated macrophages can promote growth of cancers. In neuroblastoma, tumor-associated macrophages have greater frequency in metastatic versus loco-regional tumors, and higher expression of genes associated with macrophages helps to predict poor prognosis in the 60% of high-risk patients who have MYCN-non-amplified disease. The contribution of cytotoxic T-lymphocytes to anti-neuroblastoma immune responses may be limited by low MHC class I expression and low exonic mutation frequency. Therefore, we modelled human neuroblastoma in T-cell deficient mice to examine whether depletion of monocytes/macrophages from the neuroblastoma microenvironment by blockade of CSF-1R can improve the response to chemotherapy. In vitro, CSF-1 was released by neuroblastoma cells, and topotecan increased this release. In vivo, neuroblastomas formed by subcutaneous co-injection of human neuroblastoma cells and human monocytes into immunodeficient NOD/SCID mice had fewer human CD14 + and CD163 + cells and mouse F4/80 + cells after CSF-1R blockade. In subcutaneous or intra-renal models in immunodeficient NSG or NOD/SCID mice, CSF-1R blockade alone did not affect tumor growth or mouse survival. However, when combined with cyclophosphamide plus topotecan, the CSF-1R inhibitor BLZ945, either without or with anti-human and anti-mouse CSF-1 mAbs, inhibited neuroblastoma growth and synergistically improved mouse survival. These findings indicate that depletion of tumor-associated macrophages from neuroblastomas can be associated with increased chemotherapeutic efficacy without requiring a contribution from T-lymphocytes, suggesting the possibility that combination of CSF-1R blockade with chemotherapy might be effective in patients who have limited anti-tumor T-cell responses. © 2018 UICC.

  5. 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

  6. 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

  7. Chronic Blockade of Brain Endothelin Receptor Type-A (ETA) Reduces Blood Pressure and Prevents Catecholaminergic Overactivity in the Right Olfactory Bulb of DOCA-Salt Hypertensive Rats.

    PubMed

    Cassinotti, Luis R; Guil, María J; Schöller, Mercedes I; Navarro, Mónica P; Bianciotti, Liliana G; Vatta, Marcelo S

    2018-02-27

    Overactivity of the sympathetic nervous system and central endothelins (ETs) are involved in the development of hypertension. Besides the well-known brain structures involved in the regulation of blood pressure like the hypothalamus or locus coeruleus, evidence suggests that the olfactory bulb (OB) also modulates cardiovascular function. In the present study, we evaluated the interaction between the endothelinergic and catecholaminergic systems in the OB of deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Following brain ET receptor type A (ET A ) blockade by BQ610 (selective antagonist), transcriptional, traductional, and post-traductional changes in tyrosine hydroxylase (TH) were assessed in the OB of normotensive and DOCA-salt hypertensive rats. Time course variations in systolic blood pressure and heart rate were also registered. Results showed that ET A blockade dose dependently reduced blood pressure in hypertensive rats, but it did not change heart rate. It also prevented the increase in TH activity and expression (mRNA and protein) in the right OB of hypertensive animals. However, ET A blockade did not affect hemodynamics or TH in normotensive animals. Present results support that brain ET A are not involved in blood pressure regulation in normal rats, but they significantly contribute to chronic blood pressure elevation in hypertensive animals. Changes in TH activity and expression were observed in the right but not in the left OB, supporting functional asymmetry, in line with previous studies regarding cardiovascular regulation. Present findings provide further evidence on the role of ETs in the regulation of catecholaminergic activity and the contribution of the right OB to DOCA-salt hypertension.

  8. 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.

  9. Left ventricular wall stress and sarcoplasmic reticulum Ca(2+)-ATPase gene expression in renal hypertensive rats: dose-dependent effects of ACE inhibition and AT1-receptor blockade.

    PubMed

    Zierhut, W; Studer, R; Laurent, D; Kästner, S; Allegrini, P; Whitebread, S; Cumin, F; Baum, H P; de Gasparo, M; Drexler, H

    1996-05-01

    Cardiac hypertrophy is associated with altered Ca2+ handling and may predispose to the development of LV dysfunction and cardiac failure. At the cellular level, the re-expression of ANF represents a well-established marker of myocyte hypertrophy while the decreased expression of the sarcoplasmatic reticulum (SR) Ca(2+)-ATPase is thought o play a crucial role in the alterations of Ca2+ handling and LV function. We assessed the dose-dependent effect of chronic ACE inhibition or AT1 receptor blockade on cardiac function in relation to the cardiac expression of the SR Ca(2+)-ATPase and ANF. Renal hypertensive rats (2K-1C) were treated for 12 weeks with three different doses of the ACE inhibitor benazepril, the AT1-receptor antagonist valsartan (each drug 0.3, 3, and 10 mg/kg per day i.p.) or placebo. LV dimensions, hypertrophy and wall stress were determined in vivo by magnetic resonance imaging and the gene expressions of ANF and SR Ca(2+)-ATPase were quantified by Northern blot. Low doses of both drugs did not affect blood pressure, hypertrophy, systolic wall stress and the ANF and SR Ca(2+)-ATPase gene expression. High doses of each drug reduced systolic blood pressure, wall stress, and LV hypertrophy to a similar extent and to values comparable to normotensive, age-matched rats. In addition, high dose treatment reduced LV end-systolic and end-diastolic volume as compared to untreated 2K-1C animals and normalized the mRNA levels of both ANF and SR Ca(2+)-ATPase (as compared to normotensive animals). We conclude that in this model, high doses of ACE inhibition and AT1-receptor blockade are necessary to normalize systolic blood pressure, LV hypertrophy and systolic LV wall stress which, in turn, is associated with restoration of a normal cardiac phenotype with respect to SR Ca(2+)-ATPase and ANF and normalization of cardiac function.

  10. 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.

  11. 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.

  12. Differential Effects of Systemic Cholinergic Receptor Blockade on Pavlovian Incentive Motivation and Goal-Directed Action Selection

    PubMed Central

    Ostlund, Sean B; Kosheleff, Alisa R; Maidment, Nigel T

    2014-01-01

    Reward-seeking actions can be guided by external cues that signal reward availability. For instance, when confronted with a stimulus that signals sugar, rats will prefer an action that produces sugar over a second action that produces grain pellets. Action selection is also sensitive to changes in the incentive value of potential rewards. Thus, rats that have been prefed a large meal of sucrose will prefer a grain-seeking action to a sucrose-seeking action. The current study investigated the dependence of these different aspects of action selection on cholinergic transmission. Hungry rats were given differential training with two unique stimulus-outcome (S1-O1 and S2-O2) and action-outcome (A1-O1 and A2-O2) contingencies during separate training phases. Rats were then given a series of Pavlovian-to-instrumental transfer tests, an assay of cue-triggered responding. Before each test, rats were injected with scopolamine (0, 0.03, or 0.1 mg/kg, intraperitoneally), a muscarinic receptor antagonist, or mecamylamine (0, 0.75, or 2.25 mg/kg, intraperitoneally), a nicotinic receptor antagonist. Although the reward-paired cues were capable of biasing action selection when rats were tested off-drug, both anticholinergic treatments were effective in disrupting this effect. During a subsequent round of outcome devaluation testing—used to assess the sensitivity of action selection to a change in reward value—we found no effect of either scopolamine or mecamylamine. These results reveal that cholinergic signaling at both muscarinic and nicotinic receptors mediates action selection based on Pavlovian reward expectations, but is not critical for flexibly selecting actions using current reward values. PMID:24370780

  13. Angiotensin II type 1 receptor blockade does not enhance apoptotic cell death during ischemia and reperfusion in humans in vivo.

    PubMed

    Meijer, Patrick; Wouters, Constantijn W; Oyen, Wim J; Boerman, Otto C; Scheffer, Gert Jan; Smits, Paul; Rongen, Gerard A

    2011-06-01

    Despite the theoretical benefits, angiotensin II type 1 receptor antagonists seem to enhance rather than reduce morbidity and mortality after myocardial infarction compared with angiotensin-converting enzyme inhibitors. This may result from unopposed angiotensin II type 2 receptor stimulation, which is associated with enhanced apoptotic cell death and increased infarct size. We studied whether the clinical effectiveness of irbesartan is hampered by enhanced apoptotic activity, detected by exposition of phosphatidylserines, during ischemia and reperfusion in humans in vivo. Twenty healthy male volunteers were randomized to a 1-week treatment with irbesartan (300 mg/d) or placebo in a double-blind fashion. After treatment, all participants underwent 10 minutes of ischemic exercise of the nondominant forearm. Upon reperfusion, Tc-99m-labeled Annexin A5 was administered, and 1 and 4 hours afterward, both hands were scanned using a gamma camera. Targeting of annexin A5, expressed as the percentage difference in radioactivity in the area of interest (thenar muscle) between experimental and control hand, did not differ between participants treated with irbesartan or placebo. Therefore, irbesartan does not enhance phosphatidylserine exposition in humans in vivo. The results of this study do not support enhanced apoptotic activity after treatment with irbesartan in a setting of ischemia and reperfusion.

  14. 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

  15. Selective verbal and spatial memory impairment after 5-HT1A and 5-HT2A receptor blockade in healthy volunteers pre-treated with an SSRI.

    PubMed

    Wingen, M; Kuypers, K P C; Ramaekers, J G

    2007-07-01

    Serotonergic neurotransmission has been implicated in memory impairment. It is unclear however if memory performance is mediated through general 5-HT availability, through specific 5-HT receptors or both. The aim of the present study was to assess the contribution of 5-HT reuptake inhibition and specific blockade of 5-HT(1A) and 5-HT(2A) receptors to memory impairment. The study was conducted according to a randomized, double-blind, placebo-controlled, four-way cross-over design including 16 healthy volunteers. The treatment consisted of oral administration of escitalopram 20 mg + placebo, escitalopram 20 mg + ketanserin 50 mg, escitalopram 20 mg + pindolol 10 mg and placebo on 4 separate days with a washout period of minimum 7 days. Different memory tasks were performed including verbal memory, spatial working memory and reversal learning. Escitalopram showed an impairing effect on immediate verbal recall which nearly reached statistical significance. No effects of escitalopram were found on other types of memory. In combination with pindolol, immediate verbal recall was significantly impaired. Escitalopram in combination with ketanserin impaired spatial working memory significantly. No effects were found on reversal learning. Selective impairment of immediate verbal recall after a 5-HT(1A) partial agonist and selective impairment of spatial working memory performance after 5-HT(2A) receptor antagonist, both in combination with a selective serotonergic reuptake inhibitor (escitalopram), suggests that 5-HT(1A) and 5-HT(2A) receptors are distinctly involved in verbal and spatial memory.

  16. Significant blockade of multiple receptor tyrosine kinases by MGCD516 (Sitravatinib), a novel small molecule inhibitor, shows potent anti-tumor activity in preclinical models of sarcoma.

    PubMed

    Patwardhan, Parag P; Ivy, Kathryn S; Musi, Elgilda; de Stanchina, Elisa; Schwartz, Gary K

    2016-01-26

    Sarcomas are rare but highly aggressive mesenchymal tumors with a median survival of 10-18 months for metastatic disease. Mutation and/or overexpression of many receptor tyrosine kinases (RTKs) including c-Met, PDGFR, c-Kit and IGF1-R drive defective signaling pathways in sarcomas. MGCD516 (Sitravatinib) is a novel small molecule inhibitor targeting multiple RTKs involved in driving sarcoma cell growth. In the present study, we evaluated the efficacy of MGCD516 both in vitro and in mouse xenograft models in vivo. MGCD516 treatment resulted in significant blockade of phosphorylation of potential driver RTKs and induced potent anti-proliferative effects in vitro. Furthermore, MGCD516 treatment of tumor xenografts in vivo resulted in significant suppression of tumor growth. Efficacy of MGCD516 was superior to imatinib and crizotinib, two other well-studied multi-kinase inhibitors with overlapping target specificities, both in vitro and in vivo. This is the first report describing MGCD516 as a potent multi-kinase inhibitor in different models of sarcoma, superior to imatinib and crizotinib. Results from this study showing blockade of multiple driver signaling pathways provides a rationale for further clinical development of MGCD516 for the treatment of patients with soft-tissue sarcoma.

  17. Significant blockade of multiple receptor tyrosine kinases by MGCD516 (Sitravatinib), a novel small molecule inhibitor, shows potent anti-tumor activity in preclinical models of sarcoma

    PubMed Central

    Musi, Elgilda; de Stanchina, Elisa; Schwartz, Gary K.

    2016-01-01

    Sarcomas are rare but highly aggressive mesenchymal tumors with a median survival of 10–18 months for metastatic disease. Mutation and/or overexpression of many receptor tyrosine kinases (RTKs) including c-Met, PDGFR, c-Kit and IGF1-R drive defective signaling pathways in sarcomas. MGCD516 (Sitravatinib) is a novel small molecule inhibitor targeting multiple RTKs involved in driving sarcoma cell growth. In the present study, we evaluated the efficacy of MGCD516 both in vitro and in mouse xenograft models in vivo. MGCD516 treatment resulted in significant blockade of phosphorylation of potential driver RTKs and induced potent anti-proliferative effects in vitro. Furthermore, MGCD516 treatment of tumor xenografts in vivo resulted in significant suppression of tumor growth. Efficacy of MGCD516 was superior to imatinib and crizotinib, two other well-studied multi-kinase inhibitors with overlapping target specificities, both in vitro and in vivo. This is the first report describing MGCD516 as a potent multi-kinase inhibitor in different models of sarcoma, superior to imatinib and crizotinib. Results from this study showing blockade of multiple driver signaling pathways provides a rationale for further clinical development of MGCD516 for the treatment of patients with soft-tissue sarcoma. PMID:26675259

  18. 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

  19. 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

  20. Ca(2+) signals mediated by bradykinin type 2 receptors in normal pancreatic stellate cells can be inhibited by specific Ca(2+) channel blockade.

    PubMed

    Gryshchenko, Oleksiy; Gerasimenko, Julia V; Gerasimenko, Oleg V; Petersen, Ole H

    2016-01-15

    Bradykinin may play a role in the autodigestive disease acute pancreatitis, but little is known about its pancreatic actions. In this study, we have investigated bradykinin-elicited Ca(2+) signal generation in normal mouse pancreatic lobules. We found complete separation of Ca(2+) signalling between pancreatic acinar (PACs) and stellate cells (PSCs). Pathophysiologically relevant bradykinin concentrations consistently evoked Ca(2+) signals, via B2 receptors, in PSCs but never in neighbouring PACs, whereas cholecystokinin, consistently evoking Ca(2+) signals in PACs, never elicited Ca(2+) signals in PSCs. The bradykinin-elicited Ca(2+) signals were due to initial Ca(2+) release from inositol trisphosphate-sensitive stores followed by Ca(2+) entry through Ca(2+) release-activated channels (CRACs). The Ca(2+) entry phase was effectively inhibited by a CRAC blocker. B2 receptor blockade reduced the extent of PAC necrosis evoked by pancreatitis-promoting agents and we therefore conclude that bradykinin plays a role in acute pancreatitis via specific actions on PSCs. Normal pancreatic stellate cells (PSCs) are regarded as quiescent, only to become activated in chronic pancreatitis and pancreatic cancer. However, we now report that these cells in their normal microenvironment are far from quiescent, but are capable of generating substantial Ca(2+) signals. We have compared Ca(2+) signalling in PSCs and their better studied neighbouring acinar cells (PACs) and found complete separation of Ca(2+) signalling in even closely neighbouring PACs and PSCs. Bradykinin (BK), at concentrations corresponding to the slightly elevated plasma BK levels that have been shown to occur in the auto-digestive disease acute pancreatitis in vivo, consistently elicited substantial Ca(2+) signals in PSCs, but never in neighbouring PACs, whereas the physiological PAC stimulant cholecystokinin failed to evoke Ca(2+) signals in PSCs. The BK-induced Ca(2+) signals were mediated by B2 receptors and B2

  1. 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.

  2. 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.

  3. Blockade of epidermal growth factor receptor signaling leads to inhibition of renal cell carcinoma growth in the bone of nude mice.

    PubMed

    Weber, Kristy L; Doucet, Michele; Price, Janet E; Baker, Cheryl; Kim, Sun Jin; Fidler, Isaiah J

    2003-06-01

    Renal cell carcinoma (RCC) frequently produces metastases to the musculoskeletal system that are a major source of morbidity in the form of pain, immobilization, fractures, neurological compromise, and a decreased ability to perform activities of daily living. Patients with metastatic RCC therefore have a dismal prognosis because there is no effective adjuvant treatment for this disease. Because the epidermal growth factor receptor (EGF-R) signaling cascade is important in the growth and metastasis of RCC, its blockade has been hypothesized to inhibit tumor growth and hence prevent resultant bone destruction. We determined whether blockade of EGF-R by the tyrosine kinase inhibitor PKI 166 inhibited the growth of RCC in bone. We use a novel cell line, RBM1-IT4, established from a human RCC bone metastasis. Protein and mRNA expression of the ligands and receptors was assessed by Western and Northern blots. The stimulation of RBM1-IT4 cells with epidermal growth factor or transforming growth factor alpha resulted in increased cellular proliferation and tyrosine kinase autophosphorylation. PKI 166 prevented these effects. First, RBM1-IT4 cells were implanted into the tibia of nude mice, where they established lytic, progressively growing lesions, after which the mice were treated with PKI 166 alone or in combination with paclitaxel (Taxol). Immunohistochemical analysis revealed that tumor cells and tumor-associated endothelial cells in control mice expressed activated EGF-R. Treatment of mice with PKI 166 alone or in combination with Taxol produced a significant decrease in the incidence and size of bone lesions as compared with the results in control or Taxol-treated mice (P < 0.001). Treatment with PKI 166 also decreased the expression of phosphorylated EGF-R by tumor cells and tumor-associated endothelial cells, and this was even more pronounced with PKI 166 plus Taxol treatment. The PKI 166 plus Taxol combination produced apoptosis of tumor cells and tumor

  4. Lack of weight gain after angiotensin AT1 receptor blockade in diet-induced obesity is partly mediated by an angiotensin-(1–7)/ Mas-dependent pathway

    PubMed Central

    Schuchard, Johanna; Winkler, Martina; Stölting, Ines; Schuster, Franziska; Vogt, Florian M; Barkhausen, Jörg; Thorns, Christoph; Santos, Robson A; Bader, Michael; Raasch, Walter

    2015-01-01

    Background and Purpose Angiotensin AT1 receptor antagonists induce weight loss; however, the mechanism underlying this phenomenon is unknown. The Mas receptor agonist angiotensin-(1-7) is a metabolite of angiotensin I and of angiotensin II. As an agonist of Mas receptors, angiotensin-(1-7) has beneficial cardiovascular and metabolic effects. Experimental Approach We investigated the anti-obesity effects of transgenically overexpressed angiotensin-(1-7) in rats. We secondly examined whether weight loss due to telmisartan (8 mg·kg−1·d−1) in diet-induced obese Sprague Dawley (SD) rats can be blocked when the animals were co-treated with the Mas receptor antagonist A779 (24 or 72 μg·kg−1·d−1). Key Results In contrast to wild-type controls, transgenic rats overexpressing angiotensin-(1-7) had 1.) diminished body weight when they were regularly fed with chow; 2.) were protected from developing obesity although they were fed with cafeteria diet (CD); 3.) showed a reduced energy intake that was mainly related to a lower CD intake; 5.) remained responsive to leptin despite chronic CD feeding; 6.) had a higher, strain-dependent energy expenditure, and 7.) were protected from developing insulin resistance despite CD feeding. Telmisartan-induced weight loss in SD rats was partially antagonized after a high, but not a low dose of A779. Conclusions and Implications Angiotensin-(1-7) regulated food intake and body weight and contributed to the weight loss after AT1 receptor blockade. Angiotensin-(1-7)-like agonists may be drug candidates for treating obesity. PMID:25906670

  5. AT1 and aldosterone receptors blockade prevents the chronic effect of nandrolone on the exercise-induced cardioprotection in perfused rat heart subjected to ischemia and reperfusion.

    PubMed

    Marques-Neto, Silvio Rodrigues; Ferraz, Emanuelle Baptista; Rodrigues, Deivid Carvalho; Njaine, Brian; Rondinelli, Edson; Campos de Carvalho, Antônio Carlos; Nascimento, Jose Hamilton Matheus

    2014-04-01

    Myocardial tolerance to ischaemia/reperfusion (I/R) injury is improved by exercise training, but this cardioprotection is impaired by the chronic use of anabolic androgenic steroids (AAS). The present study evaluated whether blockade of angiotensin II receptor (AT1-R) with losartan and aldosterone receptor (mineralocorticoid receptor, MR) with spironolactone could prevent the deleterious effect of AAS on the exercise-induced cardioprotection. Male Wistar rats were exercised and treated with either vehicle, nandrolone decanoate (10 mg/kg/week i.m.) or the same dose of nandrolone plus losartan or spironolactone (20 mg/kg/day orally) for 8 weeks. Langendorff-perfused hearts were subjected to I/R and evaluated for the postischaemic recovery of left ventricle (LV) function and infarct size. mRNA and protein expression of angiotensin II type 1 receptor (AT1-R), mineralocorticoid receptor (MR), and KATP channels were determined by reverse-transcriptase polymerase chain reaction and Western blotting. Postischaemic recovery of LV function was better and infarct size was smaller in the exercised rat hearts than in the sedentary rat hearts. Nandrolone impaired the exercise-induced cardioprotection, but this effect was prevented by losartan (AT1-R antagonist) and spironolactone (MR antagonist) treatments. Myocardial AT1-R and MR expression levels were increased, and the expression of the KATP channel subunits SUR2a and Kir6.1 was decreased and Kir6.2 increased in the nandrolone-treated rat hearts. The nandrolone-induced changes of AT1-R, MR, and KATP subunits expression was normalized by the losartan and spironolactone treatments. The chronic nandrolone treatment impairs the exercise-induced cardioprotection against ischaemia/reperfusion injury by activating the cardiac renin-angiotensin-aldosterone system and downregulating KATP channel expression.

  6. Adenosine A2A receptor blockade prevents synaptotoxicity and memory dysfunction caused by beta-amyloid peptides via p38 mitogen-activated protein kinase pathway.

    PubMed

    Canas, Paula M; Porciúncula, Lisiane O; Cunha, Geanne M A; Silva, Carla G; Machado, Nuno J; Oliveira, Jorge M A; Oliveira, Catarina R; Cunha, Rodrigo A

    2009-11-25

    Alzheimer's disease (AD) is characterized by memory impairment, neurochemically by accumulation of beta-amyloid peptide (namely Abeta(1-42)) and morphologically by an initial loss of nerve terminals. Caffeine consumption prevents memory dysfunction in different models, which is mimicked by antagonists of adenosine A(2A) receptors (A(2A)Rs), which are located in synapses. Thus, we now tested whether A(2A)R blockade prevents the early Abeta(1-42)-induced synaptotoxicity and memory dysfunction and what are the underlying signaling pathways. The intracerebral administration of soluble Abeta(1-42) (2 nmol) in rats or mice caused, 2 weeks later, memory impairment (decreased performance in the Y-maze and object recognition tests) and a loss of nerve terminal markers (synaptophysin, SNAP-25) without overt neuronal loss, astrogliosis, or microgliosis. These were prevented by pharmacological blockade [5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine (SCH58261); 0.05 mg . kg(-1) . d(-1), i.p.; for 15 d] in rats, and genetic inactivation of A(2A)Rs in mice. Moreover, these were synaptic events since purified nerve terminals acutely exposed to Abeta(1-42) (500 nm) displayed mitochondrial dysfunction, which was prevented by A(2A)R blockade. SCH58261 (50 nm) also prevented the initial synaptotoxicity (loss of MAP-2, synaptophysin, and SNAP-25 immunoreactivity) and subsequent loss of viability of cultured hippocampal neurons exposed to Abeta(1-42) (500 nm). This A(2A)R-mediated control of neurotoxicity involved the control of Abeta(1-42)-induced p38 phosphorylation and was independent from cAMP/PKA (protein kinase A) pathway. Together, these results show that A(2A)Rs play a crucial role in the development of Abeta-induced synaptotoxicity leading to memory dysfunction through a p38 MAPK (mitogen-activated protein kinase)-dependent pathway and provide a molecular basis for the benefits of caffeine consumption in AD.

  7. Opioid systems in the response to inflammatory pain: sustained blockade suggests role of kappa- but not mu-opioid receptors in the modulation of nociception, behaviour and pathology.

    PubMed

    Millan, M J; Colpaert, F C

    1991-01-01

    received the high but not the low dose, this transfer was blocked. It is concluded that blockade of kappa-opioid receptors with a high dose of naloxone experts pronounced functional effects in unilaterally inflamed rats. In distinction, selective blockade of mu-receptors with a low dose is ineffective. The changes seen include not only an enhancement of the hyperalgesia of the inflamed tissue, but also an exacerbation of variables (body weight, food intake and motility) which reflect pain states.(ABSTRACT TRUNCATED AT 400 WORDS)

  8. P2Y12 Receptor Localizes in the Renal Collecting Duct and Its Blockade Augments Arginine Vasopressin Action and Alleviates Nephrogenic Diabetes Insipidus.

    PubMed

    Zhang, Yue; Peti-Peterdi, Janos; Müller, Christa E; Carlson, Noel G; Baqi, Younis; Strasburg, David L; Heiney, Kristina M; Villanueva, Karie; Kohan, Donald E; Kishore, Bellamkonda K

    2015-12-01

    P2Y12 receptor (P2Y12-R) signaling is mediated through Gi, ultimately reducing cellular cAMP levels. Because cAMP is a central modulator of arginine vasopressin (AVP)-induced water transport in the renal collecting duct (CD), we hypothesized that if expressed in the CD, P2Y12-R may play a role in renal handling of water in health and in nephrogenic diabetes insipidus. We found P2Y12-R mRNA expression in rat kidney, and immunolocalized its protein and aquaporin-2 (AQP2) in CD principal cells. Administration of clopidogrel bisulfate, an irreversible inhibitor of P2Y12-R, significantly increased urine concentration and AQP2 protein in the kidneys of Sprague-Dawley rats. Notably, clopidogrel did not alter urine concentration in Brattleboro rats that lack AVP. Clopidogrel administration also significantly ameliorated lithium-induced polyuria, improved urine concentrating ability and AQP2 protein abundance, and reversed the lithium-induced increase in free-water excretion, without decreasing blood or kidney tissue lithium levels. Clopidogrel administration also augmented the lithium-induced increase in urinary AVP excretion and suppressed the lithium-induced increase in urinary nitrates/nitrites (nitric oxide production) and 8-isoprostane (oxidative stress). Furthermore, selective blockade of P2Y12-R by the reversible antagonist PSB-0739 in primary cultures of rat inner medullary CD cells potentiated the expression of AQP2 and AQP3 mRNA, and cAMP production induced by dDAVP (desmopressin). In conclusion, pharmacologic blockade of renal P2Y12-R increases urinary concentrating ability by augmenting the effect of AVP on the kidney and ameliorates lithium-induced NDI by potentiating the action of AVP on the CD. This strategy may offer a novel and effective therapy for lithium-induced NDI. Copyright © 2015 by the American Society of Nephrology.

  9. Progesterone receptor blockade in human breast cancer cells decreases cell cycle progression through G2/M by repressing G2/M genes.

    PubMed

    Clare, Susan E; Gupta, Akash; Choi, MiRan; Ranjan, Manish; Lee, Oukseub; Wang, Jun; Ivancic, David Z; Kim, J Julie; Khan, Seema A

    2016-05-23

    The synthesis of specific, potent progesterone antagonists adds potential agents to the breast cancer prevention and treatment armamentarium. The identification of individuals who will benefit from these agents will be a critical factor for their clinical success. We utilized telapristone acetate (TPA; CDB-4124) to understand the effects of progesterone receptor (PR) blockade on proliferation, apoptosis, promoter binding, cell cycle progression, and gene expression. We then identified a set of genes that overlap with human breast luteal-phase expressed genes and signify progesterone activity in both normal breast cells and breast cancer cell lines. TPA administration to T47D cells results in a 30 % decrease in cell number at 24 h, which is maintained over 72 h only in the presence of estradiol. Blockade of progesterone signaling by TPA for 24 h results in fewer cells in G2/M, attributable to decreased expression of genes that facilitate the G2/M transition. Gene expression data suggest that TPA affects several mechanisms that progesterone utilizes to control gene expression, including specific post-translational modifications, and nucleosomal organization and higher order chromatin structure, which regulate access of PR to its DNA binding sites. By comparing genes induced by the progestin R5020 in T47D cells with those increased in the luteal-phase normal breast, we have identified a set of genes that predict functional progesterone signaling in tissue. These data will facilitate an understanding of the ways in which drugs such as TPA may be utilized for the prevention, and possibly the therapy, of human breast cancer.

  10. Effects of angiotensin II receptor blockade on cerebral, cardiovascular, counter-regulatory, and symptomatic responses during hypoglycaemia in patients with type 1 diabetes.

    PubMed

    Færch, Louise H; Thorsteinsson, Birger; Tarnow, Lise; Holst, Jens Juul; Kjær, Troels; Kanters, Jørgen; Larroude, Charlotte; Dela, Flemming; Pedersen-Bjergaard, Ulrik

    2015-12-01

    High spontaneous activity of the renin-angiotensin system (RAS) results in more pronounced cognitive impairment and more prolonged QTc interval during hypoglycaemia in type 1 diabetes. We tested whether angiotensin II receptor blockade improves cerebral and cardiovascular function during hypoglycaemia. Nine patients with type 1 diabetes and high spontaneous RAS activity were included in a double-blind, randomised, cross-over study on the effect of angiotensin II receptor antagonist (candesartan 32 mg) or placebo for one week on cognitive function, cardiovascular parameters, hormonal counter-regulatory response, substrate mobilisation, and symptoms during hypoglycaemia induced by two hyperinsulinaemic, hypoglycaemic clamps. Compared to placebo, candesartan did neither change performance of the cognitive tests nor the EEG at a plasma glucose concentration of 2.6±0.2 mmol/l. During candesartan treatment, the QT interval in the ECG was not affected. No effect of candesartan was observed in the hormonal counter-regulatory responses, in substrate concentrations, or in symptom scores. A 36% reduced glucose infusion rate during hypoglycaemia with candesartan was observed. In conclusion candesartan has no effect on cerebral function during mild experimental hypoglycaemia in subjects with type 1 diabetes and high RAS activity. Candesartan may reduce glucose utilisation or increase endogenous glucose production during hypoglycaemia. © The Author(s) 2014.

  11. Effects of central histamine receptors blockade on GABA(A) agonist-induced food intake in broiler cockerels.

    PubMed

    Morteza, Zendehdel; Vahhab, Babapour; Hossein, Jonaidi

    2008-02-01

    In this study, the effect of intracerebroventricular (i.c.v) injection of H1, H2 and H3 antagonists on feed intake induced by GABA(A) agonist was evaluated. In Experiment 1, the animals received chloropheniramine, a H1 antagonist and then muscimol, a GABA(A) agonist. In Experiment 2, chickens received famotidine, a H2 receptor antagonist, prior to injection of muscimol. Finally in Experiment 3, the birds were injected with thioperamide, a H3 receptor antagonist and muscimol. Cumulative food intake was measured 15, 30, 45, 60, 90, 120, 150 and 180 min after injections. The results of this study indicated that effects of muscimol on food intake inhibited by pretreatment with chloropheneramine maleate (p < or = 0.05), significantly, while the famotidine and thioperamide were ineffective. These results suggest the existence of H1-receptor mediated histamine-GABA(A) receptor interaction on food intake in broiler cockerels.

  12. Phase III, Randomized Study of Dual Human Epidermal Growth Factor Receptor 2 (HER2) Blockade With Lapatinib Plus Trastuzumab in Combination With an Aromatase Inhibitor in Postmenopausal Women With HER2-Positive, Hormone Receptor-Positive Metastatic Breast Cancer: ALTERNATIVE.

    PubMed

    Johnston, Stephen R D; Hegg, Roberto; Im, Seock-Ah; Park, In Hae; Burdaeva, Olga; Kurteva, Galina; Press, Michael F; Tjulandin, Sergei; Iwata, Hiroji; Simon, Sergio D; Kenny, Sarah; Sarp, Severine; Izquierdo, Miguel A; Williams, Lisa S; Gradishar, William J

    2018-03-10

    Purpose Human epidermal growth factor receptor 2 (HER2) targeting plus endocrine therapy (ET) improved clinical benefit in HER2-positive, hormone receptor (HR)-positive metastatic breast cancer (MBC) versus ET alone. Dual HER2 blockade enhances clinical benefit versus single HER2 blockade. The ALTERNATIVE study evaluated the efficacy and safety of dual HER2 blockade plus aromatase inhibitor (AI) in postmenopausal women with HER2-positive/HR-positive MBC who received prior ET and prior neo(adjuvant)/first-line trastuzumab (TRAS) plus chemotherapy. Methods Patients were randomly assigned (1:1:1) to receive lapatinib (LAP) + TRAS + AI, TRAS + AI, or LAP + AI. Patients for whom chemotherapy was intended were excluded. The primary end point was progression-free survival (PFS; investigator assessed) with LAP + TRAS + AI versus TRAS + AI. Secondary end points were PFS (comparison of other arms), overall survival, overall response rate, clinical benefit rate, and safety. Results Three hundred fifty-five patients were included in this analysis: LAP + TRAS + AI (n = 120), TRAS + AI (n = 117), and LAP + AI (n = 118). Baseline characteristics were balanced. The study met its primary end point; superior PFS was observed with LAP + TRAS + AI versus TRAS + AI (median PFS, 11 v 5.7 months; hazard ratio, 0.62; 95% CI, 0.45 to 0.88; P = .0064). Consistent PFS benefit was observed in predefined subgroups. Overall response rate, clinical benefit rate, and overall survival also favored LAP + TRAS + AI. The median PFS with LAP + AI versus TRAS + AI was 8.3 versus 5.7 months (hazard ratio, 0.71; 95% CI, 0.51 to 0.98; P = .0361). Common adverse events (AEs; ≥ 15%) with LAP + TRAS + AI, TRAS + AI, and LAP + AI were diarrhea (69%, 9%, and 51%, respectively), rash (36%, 2%, and 28%, respectively), nausea (22%, 9%, and 22%, respectively), and paronychia (30%, 0%, and 15%, respectively), mostly grade 1 or 2. Serious AEs were reported similarly across the three groups, and AEs leading to

  13. A novel muscarinic receptor-independent mechanism of KCNQ2/3 potassium channel blockade by Oxotremorine-M.

    PubMed

    Zwart, Ruud; Reed, Hannah; Clarke, Sophie; Sher, Emanuele

    2016-11-15

    Inhibition of KCNQ (Kv7) potassium channels by activation of muscarinic acetylcholine receptors has been well established, and the ion currents through these channels have been long known as M-currents. We found that this cross-talk can be reconstituted in Xenopus oocytes by co-transfection of human recombinant muscarinic M1 receptors and KCNQ2/3 potassium channels. Application of the muscarinic acetylcholine receptor agonist Oxotremorine-methiodide (Oxo-M) between voltage pulses to activate KCNQ2/3 channels caused inhibition of the subsequent KCNQ2/3 responses. This effect of Oxo-M was blocked by the muscarinic acetylcholine receptor antagonist atropine. We also found that KCNQ2/3 currents were inhibited when Oxo-M was applied during an ongoing KCNQ2/3 response, an effect that was not blocked by atropine, suggesting that Oxo-M inhibits KCNQ2/3 channels directly. Indeed, also in oocytes that were transfected with only KCNQ2/3 channels, but not with muscarinic M1 receptors, Oxo-M inhibited the KCNQ2/3 response. These results show that besides the usual muscarinic acetylcholine receptor-mediated inhibition, Oxo-M also inhibits KCNQ2/3 channels by a direct mechanism. We subsequently tested xanomeline, which is a chemically distinct muscarinic acetylcholine receptor agonist, and oxotremorine, which is a close analogue of Oxo-M. Both compounds inhibited KCNQ2/3 currents via activation of M1 muscarinic acetylcholine receptors but, in contrast to Oxo-M, they did not directly inhibit KCNQ2/3 channels. Xanomeline and oxotremorine do not contain a positively charged trimethylammonium moiety that is present in Oxo-M, suggesting that such a charged moiety could be a crucial component mediating this newly described direct inhibition of KCNQ2/3 channels. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. 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.

  15. Design, synthesis and biological evaluation of a bivalent micro opiate and adenosine A1 receptor antagonist.

    PubMed

    Mathew, Smitha C; Ghosh, Nandita; By, Youlet; Berthault, Aurélie; Virolleaud, Marie-Alice; Carrega, Louis; Chouraqui, Gaëlle; Commeiras, Laurent; Condo, Jocelyne; Attolini, Mireille; Gaudel-Siri, Anouk; Ruf, Jean; Parrain, Jean-Luc; Rodriguez, Jean; Guieu, Régis

    2009-12-01

    The cross talk between different membrane receptors is the source of increasing research. We designed and synthesized a new hetero-bivalent ligand that has antagonist properties on both A(1) adenosine and mu opiate receptors with a K(i) of 0.8+/-0.05 and 0.7+/-0.03 microM, respectively. This hybrid molecule increases cAMP production in cells that over express the mu receptor as well as those over expressing the A(1) adenosine receptor and reverses the antalgic effects of mu and A(1) adenosine receptor agonists in animals.

  16. 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.

  17. NMDA receptor blockade and hippocampal neuronal loss impair fear conditioning and position habit reversal in C57Bl/6 mice.

    PubMed

    Bardgett, Mark E; Boeckman, Ryan; Krochmal, Daniel; Fernando, Hiran; Ahrens, Rebecca; Csernansky, John G

    2003-04-15

    The interpretation of learning and memory deficits in transgenic mice has largely involved theories of NMDA receptor and/or hippocampal function. However, there is little empirical data that describes what NMDA receptors or the hippocampus do in mice. This research assessed the effects of different doses of the NMDA receptor antagonist, MK-801, or different-sized hippocampal lesions on several behavioral parameters in adult male C57Bl/6 mice. In the first set of experiments, different doses of MK-801 (0.05-0.3mg/kg, s.c.) were assayed in fear conditioning, shock sensitivity, locomotion, anxiety, and position habit reversal tests. Contextual and cued fear conditioning, and position habit reversal were impaired in a dose-dependent manner. Locomotor activity was increased immediately after injection of the highest dose of MK-801. A second set of experiments determined the behavioral effects of a moderate and large excitotoxic hippocampal lesion. Both lesions impaired contextual conditioning, while the larger lesion interfered with cued conditioning. Reversal learning was significantly diminished by the large lesion, while the moderate lesion had a detrimental effect at a trend level (P<0.10). These results provide important reference data for studies involving genetic manipulations of NMDA receptor or hippocampal function in mice. Furthermore, they serve as a basis for a non-transgenic mouse model of the NMDA receptor or hippocampal dysfunction hypothesized to occur in human cognitive disorders.

  18. Blockade of α2-adrenergic receptors in prelimbic cortex: impact on cocaine self-administration in adult spontaneously hypertensive rats following adolescent atomoxetine treatment.

    PubMed

    Baskin, Britahny M; Nic Dhonnchadha, Bríd Á; Dwoskin, Linda P; Kantak, Kathleen M

    2017-10-01

    Research with the spontaneously hypertensive rat (SHR) model of attention deficit/hyperactivity disorder demonstrated that chronic methylphenidate treatment during adolescence increased cocaine self-administration established during adulthood under a progressive ratio (PR) schedule. Compared to vehicle, chronic atomoxetine treatment during adolescence failed to increase cocaine self-administration under a PR schedule in adult SHR. We determined if enhanced noradrenergic transmission at α2-adrenergic receptors within prefrontal cortex contributes to this neutral effect of adolescent atomoxetine treatment in adult SHR. Following treatment from postnatal days 28-55 with atomoxetine (0.3 mg/kg) or vehicle, adult male SHR and control rats from Wistar-Kyoto (WKY) and Wistar (WIS) strains were trained to self-administer 0.3 mg/kg cocaine. Self-administration performance was evaluated under a PR schedule of cocaine delivery following infusion of the α2-adrenergic receptor antagonist idazoxan (0 and 10-56 μg/side) directly into prelimbic cortex. Adult SHR attained higher PR break points and had greater numbers of active lever responses and infusions than WKY and WIS. Idazoxan dose-dependently increased PR break points and active lever responses in SHR following adolescent atomoxetine vs. vehicle treatment. Behavioral changes were negligible after idazoxan pretreatment in SHR following adolescent vehicle or in WKY and WIS following adolescent atomoxetine or vehicle. α2-Adrenergic receptor blockade in prelimbic cortex of SHR masked the expected neutral effect of adolescent atomoxetine on adult cocaine self-administration behavior. Moreover, greater efficacy of acute idazoxan challenge in adult SHR after adolescent atomoxetine relative to vehicle is consistent with the idea that chronic atomoxetine may downregulate presynaptic α2A-adrenergic autoreceptors in SHR.

  19. 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.

  20. β-Nicotinamide adenine dinucleotide acts at prejunctional adenosine A1 receptors to suppress inhibitory musculomotor neurotransmission in guinea pig colon and human jejunum

    PubMed Central

    Wang, Guo-Du; Wang, Xi-Yu; Liu, Sumei; Xia, Yun; Zou, Fei; Qu, Meihua; Needleman, Bradley J.; Mikami, Dean J.

    2015-01-01

    Intracellular microelectrodes were used to record neurogenic inhibitory junction potentials in the intestinal circular muscle coat. Electrical field stimulation was used to stimulate intramural neurons and evoke contraction of the smooth musculature. Exposure to β-nicotinamide adenine dinucleotide (β-NAD) did not alter smooth muscle membrane potential in guinea pig colon or human jejunum. ATP, ADP, β-NAD, and adenosine, as well as the purinergic P2Y1 receptor antagonists MRS 2179 and MRS 2500 and the adenosine A1 receptor agonist 2-chloro-N6-cyclopentyladenosine, each suppressed inhibitory junction potentials in guinea pig and human preparations. β-NAD suppressed contractile force of twitch-like contractions evoked by electrical field stimulation in guinea pig and human preparations. P2Y1 receptor antagonists did not reverse this action. Stimulation of adenosine A1 receptors with 2-chloro-N6-cyclopentyladenosine suppressed the force of twitch contractions evoked by electrical field stimulation in like manner to the action of β-NAD. Blockade of adenosine A1 receptors with 8-cyclopentyl-1,3-dipropylxanthine suppressed the inhibitory action of β-NAD on the force of electrically evoked contractions. The results do not support an inhibitory neurotransmitter role for β-NAD at intestinal neuromuscular junctions. The data suggest that β-NAD is a ligand for the adenosine A1 receptor subtype expressed by neurons in the enteric nervous system. The influence of β-NAD on intestinal motility emerges from adenosine A1 receptor-mediated suppression of neurotransmitter release at inhibitory neuromuscular junctions. PMID:25813057

  1. Effect of Angiotensin II Type I Receptor Blockade with Valsartan on Carotid Artery Atherosclerosis: A Double Blind Randomized Clinical Trial Comparing Valsartan and Placebo (EFFERVESCENT).

    PubMed

    Ramadan, Ronnie; Dhawan, Saurabh S; Binongo, José Nilo G; Alkhoder, Ayman; Jones, Dean P; Oshinski, John N; Quyyumi, Arshed A

    2016-04-01

    Progression of atherosclerosis is associated with a greater risk for adverse outcomes. Angiotensin II plays a key role in the pathogenesis and progression of atherosclerosis. We aimed to investigate the effects of angiotensin II type-1 receptor blockade with Valsartan on carotid wall atherosclerosis, with the hypothesis that Valsartan will reduce progression of atherosclerosis. Subjects (n = 120) with carotid intima-media thickness >0.65 mm by ultrasound were randomized (2:1) in a double-blind manner to receive either Valsartan or placebo for 2 years. Bilateral T2-weighted black-blood carotid magnetic resonance imaging was performed at baseline, 12 and 24 months. Changes in the carotid bulb vessel wall area and wall thickness were primary endpoints. Secondary endpoints included changes in carotid plaque thickness, plasma levels of aminothiols, C-reactive protein, fibrinogen, and endothelium-dependent and -independent vascular function. Over 2 years, the carotid bulb vessel wall area decreased with Valsartan (-6.7, 95% CI [-11.6, -1.9] mm(2)) but not with placebo (3.4, 95% CI [-2.8, 9.6] mm(2)), P = .01 between groups. Similarly, mean wall thickness decreased with Valsartan (-0.18, 95% CI [-0.30, -0.06] mm), but not with placebo (0.08, 95% CI [-0.07, 0.23] mm), P = .009 between groups. Furthermore, plaque thickness decreased with Valsartan (-0.35, 95% CI [-0.63, -0.08] mm) but was unchanged with placebo (+0.28, 95% CI [-0.11, 0.69] mm), P = .01 between groups. These findings were unaffected by statin therapy or changes in blood pressure. Notably, there were significant improvements in the aminothiol cysteineglutathione disulfide, and trends to improvements in fibrinogen levels and endothelium-independent vascular function. In subjects with carotid wall thickening, angiotensin II type-1 receptor blockade was associated with regression in carotid atherosclerosis. Whether these effects translate into improved outcomes in subjects with subclinical atherosclerosis

  2. 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.

  3. The case for peripheral CB₁ receptor blockade in the treatment of visceral obesity and its cardiometabolic complications.

    PubMed

    Kunos, George; Tam, Joseph

    2011-08-01

    In this review, we consider the role of endocannabinoids and cannabinoid-1 (CB(1)) cannabinoid receptors in metabolic regulation and as mediators of the thrifty phenotype that underlies the metabolic syndrome. We survey the actions of endocannabinoids on food intake and body weight, as well as on the metabolic complications of visceral obesity, including fatty liver, insulin resistance and dyslipidemias. Special emphasis is placed on weighing the relative importance of CB(1) receptors located in peripheral tissues versus the central nervous system in mediating the metabolic effects of endocannabinoids. Finally, we review recent observations that indicate that peripherally restricted CB(1) receptor antagonists retain efficacy in reducing weight and improving metabolic abnormalities in mouse models of obesity without causing behavioural effects predictive of neuropsychiatric side effects in humans. British Journal of Pharmacology © 2011 The British Pharmacological Society. Published 2011. This article is a U.S. Government work and is in the public domain in the USA.

  4. Pharmacological Blockade of Serotonin 5-HT7 Receptor Reverses Working Memory Deficits in Rats by Normalizing Cortical Glutamate Neurotransmission

    PubMed Central

    Bonaventure, Pascal; Aluisio, Leah; Shoblock, James; Boggs, Jamin D.; Fraser, Ian C.; Lord, Brian; Lovenberg, Timothy W.; Galici, Ruggero

    2011-01-01

    The role of 5-HT7 receptor has been demonstrated in various animal models of mood disorders; however its function in cognition remains largely speculative. This study evaluates the effects of SB-269970, a selective 5-HT7 antagonist, in a translational model of working memory deficit and investigates whether it modulates cortical glutamate and/or dopamine neurotransmission in rats. The effect of SB-269970 was evaluated in the delayed non-matching to position task alone or in combination with MK-801, a non-competitive NMDA receptor antagonist, and, in separate experiments, with scopolamine, a non-selective muscarinic antagonist. SB-269970 (10 mg/kg) significantly reversed the deficits induced by MK-801 (0.1 mg/kg) but augmented the deficit induced by scopolamine (0.06 mg/kg). The ability of SB-269970 to modulate MK-801-induced glutamate and dopamine extracellular levels was separately evaluated using biosensor technology and microdialysis in the prefrontal cortex of freely moving rats. SB-269970 normalized MK-801 -induced glutamate but not dopamine extracellular levels in the prefrontal cortex. Rat plasma and brain concentrations of MK-801 were not affected by co-administration of SB-269970, arguing for a pharmacodynamic rather than a pharmacokinetic mechanism. These results indicate that 5-HT7 receptor antagonists might reverse cognitive deficits associated with NMDA receptor hypofunction by selectively normalizing glutamatergic neurotransmission. PMID:21701689

  5. Protection by imidazol(ine) drugs and agmatine of glutamate-induced neurotoxicity in cultured cerebellar granule cells through blockade of NMDA receptor

    PubMed Central

    Olmos, Gabriel; DeGregorio-Rocasolano, Nuria; Regalado, M Paz; Gasull, Teresa; Boronat, M Assumpció; Trullas, Ramón; Villarroel, Alvaro; Lerma, Juan; García-Sevilla, Jesús A

    1999-01-01

    neuroprotective against glutamate-induced necrotic neuronal cell death in vitro and that this effect is mediated through NMDA receptor blockade by interacting with a site located within the NMDA channel pore. PMID:10455281

  6. Recovery from ketamine-induced amnesia by blockade of GABA-A receptor in the medial prefrontal cortex of mice.

    PubMed

    Farahmandfar, Maryam; Akbarabadi, Ardeshir; Bakhtazad, Atefeh; Zarrindast, Mohammad-Reza

    2017-03-06

    Ketamine and other noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonists are known to induce deficits in learning and cognitive performance sensitive to prefrontal cortex (PFC) functions. The interaction of a glutamatergic and GABAergic systems is essential for many cognitive behaviors. In order to understand the effect of γ-aminobutyric acid (GABA)/glutamate interactions on learning and memory, we investigated the effects of intra medial prefrontal cortex (mPFC) injections of GABAergic agents on ketamine-induced amnesia using a one-trial passive avoidance task in mice. Pre-training systemic administration of ketamine (5, 10 and 15mg/kg, i.p.) dose-dependently decreased the memory acquisition of a one-trial passive avoidance task. Pre-training intra-mPFC injection of muscimol, GABAA receptor agonist (0.05, 0.1 and 0.2μg/mouse) and baclofen GABAB receptor agonist (0.05, 0.1, 0.5 and 1μg/mouse), impaired memory acquisition. However, co-pretreatment of different doses of muscimol and baclofen with a lower dose of ketamine (5mg/kg), which did not induce amnesia by itself, caused inhibition of memory formation. Our data showed that sole pre-training administration of bicuculline, GABA-A receptor antagonist and phaclofen GABA-B receptor antagonist into the mPFC, did not affect memory acquisition. In addition, the amnesia induced by pre-training ketamine (15mg/kg) was significantly decreased by the pretreatment of bicuculline (0.005, 0.1 and 0.5μg/mouse). It can be concluded that GABAergic system of the mPFC is involved in the ketamine-induced impairment of memory acquisition. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  7. The effect of vasopressin 1b receptor (V1bR) blockade on HPA axis activity in rats exposed to acute heat stress.

    PubMed

    Jasnic, Nebojsa; Djordjevic, Jelena; Vujovic, Predrag; Lakic, Iva; Djurasevic, Sinisa; Cvijic, Gordana

    2013-06-15

    Thermal stressors such as low and high ambient temperature elicit an abundance of neuroendocrine responses including activation of the hypothalamo-pituitary-adrenal (HPA) axis and arginine vasopressin (AVP) release. The exposure to heat is a particularly interesting model for studying AVP action because this kind of stressor represents not only an unpleasant experience but also a threat to osmotic homeostasis. As AVP has long been recognized as a hormone involved in the modulation of HPA axis activity, the aim of this study was to elucidate the role of AVP in acutely heat-exposed rats using Nelivaptan, a selective vasopressin 1b receptor (V1bR) antagonist. Rats were exposed to high ambient temperature (38°C) for 60 min. The circulating hormones were determined by ELISA or chemiluminescence, and intrapituitary adrenocorticotropic hormone (ACTH) and V1bR level were determined by western blot. The results obtained show that V1bR blockade negatively affected the increase in blood ACTH caused by heat exposure. This treatment alone, or in combination with Nelivaptan, decreased intrapituitary V1bR levels while circulating AVP concentration was increased under the same conditions. Furthermore, a strong correlation was observed between blood ACTH and corticosterone concentration. In conclusion, our results directly confirm the positive role of AVP in the regulation of ACTH secretion from the pituitary in animals exposed to heat. Moreover, the results suggest that AVP from the general circulation influences pituitary V1bR.

  8. Systemic modulation of serotonergic synapses via reuptake blockade or 5HT1A receptor antagonism does not alter perithreshold taste sensitivity in rats.

    PubMed

    Mathes, Clare M; Spector, Alan C

    2014-09-01

    Systemic blockade of serotonin (5HT) reuptake with paroxetine has been shown to increase sensitivity to sucrose and quinine in humans. Here, using a 2-response operant taste detection task, we measured the effect of paroxetine and the 5HT1A receptor antagonist WAY100635 on the ability of rats to discriminate sucrose, NaCl, and citric acid from water. After establishing individual psychometric functions, 5 concentrations of each taste stimulus were chosen to represent the dynamic portion of the concentration-response curve, and the performance of the rats to these stimuli was assessed after vehicle, paroxetine (7mg/kg intraperitoneally), and WAY100635 (0.3mg/kg subcutaneously; 1mg/kg intravenously) administration. Although, at times, overall performance across concentrations dropped, at most, 5% from vehicle to drug conditions, no differences relative to vehicle were seen on the parameters of the psychometric function (asymptote, slope, or EC50) after drug administration. In contrast to findings in humans, our results suggest that modulation of 5HT activity has little impact on sucrose detectability at perithreshold concentrations in rats, at least at the doses used in this task. In the rat model, the purported paracrine/neurocrine action of serotonin in the taste bud may work in a manner that does not impact overt taste detection behavior. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Blockade of rat alpha3beta4 nicotinic receptor function by methadone, its metabolites, and structural analogs.

    PubMed

    Xiao, Y; Smith, R D; Caruso, F S; Kellar, K J

    2001-10-01

    The opioid agonist properties of (+/-)-methadone are ascribed almost entirely to the (-)-methadone enantiomer. To extend our knowledge of the pharmacological actions of methadone at ligand-gated ion channels, we investigated the effects of the two enantiomers of methadone and its metabolites R-(+)-2-ethyl-1,5-dimethyl-3,3-diphenylpyrrolinium perchlorate (EDDP) and R-(+)-2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline hydrochloride (EMDP), as well as structural analogs of methadone, including (-)-alpha-acetylmethadol hydrochloride (LAAM) and (+)-alpha-propoxyphene, on rat alpha3beta4 neuronal nicotinic acetylcholine receptors (nAChRs) stably expressed in a human embryonic kidney 293 cell line, designated KXalpha3beta4R2. (+/-)-methadone inhibited nicotine-stimulated 86Rb+ efflux from the cells in a concentration-dependent manner with an IC50 value of 1.9 +/- 0.2 microM, indicating that it is a potent nAChR antagonist. The (-)- and (+)-enantiomers of methadone have similar inhibitory potencies on nicotine-stimulated 86Rb+ efflux, with IC50 values of approximately 2 microM. EDDP, the major metabolite of methadone, is even more potent, with an IC50 value of approximately 0.5 microM, making it one of the most potent nicotinic receptor blockers reported. In the presence of (+/-)-methadone, EDDP, or LAAM, the maximum nicotine-stimulated 86Rb+ efflux was markedly decreased, but the EC50 value for nicotine stimulation was altered only slightly, if at all, indicating that these compounds block alpha3beta4 nicotinic receptor function by a noncompetitive mechanism. Consistent with a noncompetitive mechanism, (+/-)-methadone, its metabolites, and structural analogs have very low affinity for nicotinic receptor agonist binding sites in membrane homogenates from KXalpha3beta4R2 cells. We conclude that both enantiomers of methadone and its metabolites as well as LAAM and (+)-alpha-propoxyphene are potent noncompetitive antagonists of alpha3beta4 nAChRs.

  10. Decreased Incentive Motivation Following Knockout or Acute Blockade of the Serotonin Transporter: Role of the 5-HT2C Receptor.

    PubMed

    Browne, Caleb J; Fletcher, Paul J

    2016-09-01

    Acute pharmacological elevation of serotonin (5-hydroxytryptamine; 5-HT) activity decreases operant responding for primary reinforcers, suggesting that 5-HT reduces incentive motivation. The mechanism by which 5-HT alters incentive motivation is unknown, but parallel evidence that 5-HT2C receptor agonists also reduce responding for primary reinforcers implicates this receptor as a potential candidate. These experiments examined whether chronic and acute disruptions of serotonin transporter (SERT) activity altered incentive motivation, and whether the 5-HT2C receptor mediated the effects of elevated 5-HT on behavior. To assess incentive motivation, we measured responding for three different reinforcers: a primary reinforcer (saccharin), a conditioned reinforcer (CRf), and an unconditioned sensory reinforcer (USRf). In the chronic condition, responding was compared between SERT knockout (SERT-KO) mice and their wild-type littermates. In the acute condition, responding was examined in wild-type mice following treatment with 10 or 20 mg/kg citalopram, or its vehicle. The ability of the selective 5-HT2C antagonist SB 242084 to prevent the effects of SERT-KO and citalopram on responding was subsequently examined. Both SERT-KO and citalopram reduced responding for saccharin, a CRf, and a USRf. Treatment with SB 242084 enhanced responding for a CRf and a USRf in SERT-KO mice and blocked the effects of citalopram on CRf and USRf responding. However, SB 242084 was unable to prevent the effects of SERT-KO or citalopram on responding for saccharin. These results support a powerful inhibitory function for 5-HT in the control of incentive motivation, and indicate that the 5-HT2C receptor mediates these effects of 5-HT in a reinforcer-dependent manner.

  11. Systems Biology and Birth Defects Prevention: Blockade of the Glucocorticoid Receptor Prevents Arsenic-Induced Birth Defects

    PubMed Central

    Ahir, Bhavesh K.; Sanders, Alison P.; Rager, Julia E.

    2013-01-01

    Background: The biological mechanisms by which environmental metals are associated with birth defects are largely unknown. Systems biology–based approaches may help to identify key pathways that mediate metal-induced birth defects as well as potential targets for prevention. Objectives: First, we applied a novel computational approach to identify a prioritized biological pathway that associates metals with birth defects. Second, in a laboratory setting, we sought to determine whether inhibition of the identified pathway prevents developmental defects. Methods: Seven environmental metals were selected for inclusion in the computational analysis: arsenic, cadmium, chromium, lead, mercury, nickel, and selenium. We used an in silico strategy to predict genes and pathways associated with both metal exposure and developmental defects. The most significant pathway was identified and tested using an in ovo whole chick embryo culture assay. We further evaluated the role of the pathway as a mediator of metal-induced toxicity using the in vitro midbrain micromass culture assay. Results: The glucocorticoid receptor pathway was computationally predicted to be a key mediator of multiple metal-induced birth defects. In the chick embryo model, structural malformations induced by inorganic arsenic (iAs) were prevented when signaling of the glucocorticoid receptor pathway was inhibited. Further, glucocorticoid receptor inhibition demonstrated partial to complete protection from both iAs- and cadmium-induced neurodevelopmental toxicity in vitro. Conclusions: Our findings highlight a novel approach to computationally identify a targeted biological pathway for examining birth defects prevention. PMID:23458687

  12. Effects of β-adrenergic receptor blockade on drug-related memory reconsolidation in abstinent heroin addicts.

    PubMed

    Zhao, Li-Yan; Sun, Li-Li; Shi, Jie; Li, Peng; Zhang, Yan; Lu, Lin

    2011-11-01

    The reactivation of a consolidated memory can return it to a labile state, a process referred to as reconsolidation. A previous study showed that oral administration of the β-adrenergic receptor antagonist propranolol before memory reactivation in humans erased the behavioral expression of the fear memory 24h later. In this study, we investigated whether propranolol impairs the drug-related memory by disrupting the reconsolidation process in heroin addicts. Seventy abstinent heroin addicts learned a word list (including 10 heroin-related positive words, 10 heroin-related negative words, and 10 neutral words) on day 1. Participants orally administered the β-adrenergic receptor antagonist propranolol or placebo before retrieval of the word list on day 2. Free recall of the word list and other psychological and physical responses were assessed on day 3. Oral administration of propranolol before reactivation of the word list impaired reconsolidation of drug-related positive and negative but not neutral words in abstinent heroin addicts, and these impairments critically depended on reactivation of the word list. This study extends earlier reports that a β-adrenergic receptor antagonist affects the drug-related memory reconsolidation process. Our findings may have important implications for the understanding and treatment of persistent and abnormal drug-related memories in abstinent heroin addicts. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  13. Effects of angiotensin receptor blockade (ARB) on mortality and cardiovascular outcomes in patients with long-term haemodialysis: a randomized controlled trial.

    PubMed

    Iseki, Kunitoshi; Arima, Hisatomi; Kohagura, Kentaro; Komiya, Ichiro; Ueda, Shinichiro; Tokuyama, Kiyoyuki; Shiohira, Yoshiki; Uehara, Hajime; Toma, Shigeki

    2013-06-01

    Hypertension is a major risk factor for death and cardiovascular disease (CVD) in patients undergoing chronic haemodialysis (HD), but there is uncertainty surrounding the effects of blood pressure (BP) lowering on this high-risk patient group. In a multicenter, prospective, randomized, open-label, blinded-endpoint trial, 469 patients with chronic HD and elevated BP (140-199/90-99 mmHg) were assigned to receive the angiotensin receptor blockade (ARB) olmesartan (at a dose of 10-40 mg daily; n = 235) or another treatment that does not include angiotensin receptor blockers and angiotensin-converting enzyme (ACE) inhibitors (n = 234). The primary outcomes were the following: (i) composite of death, nonfatal stroke, nonfatal myocardial infarction and coronary revascularization and (ii) all-cause death. During a mean follow-up of 3.5 years, the mean BP was 0.9/0.0 mmHg lower in the olmesartan group than in the control group (not significant). A total of 68 patients (28.9%) in the olmesartan group and 67 patients (28.6%) in the control group had subsequent primary composite endpoints [hazard ratio (HR) in the olmesartan group 1.00, 95% confidence interval (CI) 0.71-1.40, P = 0.99]. All-cause deaths occurred in 38 patients (16.2%) in the olmesartan group and 39 (16.7%) in the control group (HR, 0.97; 95% CI, 0.62-1.52, P = 0.91). Olmesartan did not alter the risks of serious adverse events. BP-lowering treatment with an ARB did not significantly lower the risks of major cardiovascular events or death among patients with hypertension on chronic HD. (Cochrane Renal Group Prospective Trial Register number CRG010600030).

  14. Blockade of adenosine A2A receptors recovers early deficits of memory and plasticity in the triple transgenic mouse model of Alzheimer's disease.

    PubMed

    Silva, António C; Lemos, Cristina; Gonçalves, Francisco Q; Pliássova, Anna V; Machado, Nuno J; Silva, Henrique B; Canas, Paula M; Cunha, Rodrigo A; Lopes, João Pedro; Agostinho, Paula

    2018-05-31

    Alzheimer's disease (AD) begins with a deficit of synaptic function and adenosine A 2A receptors (A 2A R) are mostly located in synapses controlling synaptic plasticity. The over-activation of adenosine A 2A receptors (A 2A R) causes memory deficits and the blockade of A 2A R prevents memory damage in AD models. We now enquired if this prophylactic role of A 2A R might be extended to a therapeutic potential. We used the triple transgenic model of AD (3xTg-AD) and defined that the onset of memory dysfunction occurred at 4 months of age in the absence of locomotor or emotional alterations. At the onset of memory deficits, 3xTg mice displayed a decreased density of markers of excitatory synapses (10.6 ± 3.8% decrease of vGluT1) without neuronal or glial overt damage and an increase of synaptic A 2A R in the hippocampus (130 ± 22%). After the onset of memory deficits in 3xTg-AD mice, a three weeks treatment with the selective A 2A R antagonist normalized the up-regulation of hippocampal A 2A R and restored hippocampal-dependent reference memory, as well as the decrease of hippocampal synaptic plasticity (60.0 ± 3.7% decrease of long-term potentiation amplitude) and the decrease of global (syntaxin-I) and glutamatergic synaptic markers (vGluT1). These findings show a therapeutic-like ability of A 2A R antagonists to recover synaptic and memory dysfunction in early AD. Copyright © 2018 Elsevier Inc. All rights reserved.

  15. 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

  16. Effect of Angiotensin II Type I Receptor Blockade with Valsartan on Carotid Artery Atherosclerosis: A Double Blind Randomized Clinical Trial Comparing Valsartan and Placebo (EFFERVESCENT)

    PubMed Central

    Ramadan, Ronnie; Dhawan, Saurabh S.; Binongo, José Nilo G.; Alkhoder, Ayman; Jones, Dean P.; Oshinski, John N.; Quyyumi, Arshed A.

    2016-01-01

    Background Progression of atherosclerosis is associated with a greater risk for adverse outcomes. Angiotensin II plays a key role in the pathogenesis and progression of atherosclerosis. We aimed to investigate the effects of Angiotensin II type-1 receptor (AT1R) blockade with Valsartan on carotid wall atherosclerosis, with the hypothesis that Valsartan will reduce progression of atherosclerosis. Methods Subjects (n= 120) with carotid intima-media thickness >0.65mm by ultrasound were randomized (2:1) in a double-blind manner to receive either Valsartan or placebo for 2 years. Bilateral T2-weighted black-blood carotid magnetic resonance imaging was performed at baseline, 12 and 24 months. Changes in the carotid bulb vessel wall area (VWA) and wall thickness (WT) were primary endpoints. Secondary endpoints included changes in carotid plaque thickness, plasma levels of aminothiols, C-reactive protein, fibrinogen, and endothelium-dependent and -independent vascular function. Results Over 2 years, the carotid bulb VWA decreased with Valsartan (−6.7, 95% CI: (−11.6,−1.9) mm2) but not with placebo (3.4, 95% CI: (−2.8,9.6) mm2)), p=0.01 between groups. Similarly, mean WT decreased with Valsartan (−0.18, 95% CI: (−0.30,−0.06) mm), but not with placebo (0.08, 95% CI: (−0.07,0.23) mm),), p=0.009 between groups. Furthermore, plaque thickness decreased with Valsartan (−0.35, 95% CI: (−0.63,−0.08) mm) but was unchanged with placebo (+0.28, 95% CI: (−0.11,0.69) mm), p=0.01 between groups. These findings were unaffected by statin therapy or changes in blood pressure. Notably, there were significant improvements in the aminothiol cysteineglutathione disulfide, and trends to improvements in fibrinogen levels and endothelium–independent vascular function. Conclusions In subjects with carotid wall thickening, AT1R blockade was associated with regression in carotid atherosclerosis. Whether these effects translate into improved outcomes in subjects with

  17. The relationship between dopamine receptor blockade and cognitive performance in schizophrenia: a [11C]-raclopride PET study with aripiprazole.

    PubMed

    Shin, Sangho; Kim, Seoyoung; Seo, Seongho; Lee, Jae Sung; Howes, Oliver D; Kim, Euitae; Kwon, Jun Soo

    2018-04-24

    Aripiprazole's effects on cognitive function in patients with schizophrenia are unclear because of the difficulty in disentangling specific effects on cognitive function from secondary effects due to the improvement in other schizophrenic symptoms. One approach to address this is to use an intermediate biomarker to investigate the relationship between the drug's effect on the brain and change in cognitive function. This study aims to investigate aripiprazole's effect on working memory by determining the correlation between dopamine D2/3 (D2/3) receptor occupancy and working memory of patients with schizophrenia. Seven patients with schizophrenia participated in the study. Serial positron emission tomography (PET) scans with [ 11 C]raclopride were conducted at 2, 26, and 74 h after the administration of aripiprazole. The subjects performed the N-back task just after finishing the [ 11 C]raclopride PET scan. The mean (±SD) D2/3 receptor occupancies were 66.9 ± 6.7% at 2 h, 65.0 ± 8.6% at 26, and 57.7 ± 11.2% at 74 h after administering aripiprazole. Compared with performance on the zero-back condition, performance in memory-loaded conditions (one-, two-, and three-back conditions) was significantly related to D2/3 receptor occupancy by aripiprazole (error rate: ß = -2.236, t = -6.631, df = 53.947, and p = 0.001; reaction time: ß = -9.567, t = -2.808, df = 29.967, and p = 0.009). Although the sample size was relatively small, these results suggest that aripiprazole as a dopamine-partial agonist could improve cognitive function in patients with schizophrenia.

  18. Dual Endothelin-A/Endothelin-B Receptor Blockade and Cardiac Remodeling in Heart Failure With Preserved Ejection Fraction.

    PubMed

    Valero-Munoz, Maria; Li, Shanpeng; Wilson, Richard M; Boldbaatar, Batbold; Iglarz, Marc; Sam, Flora

    2016-11-01

    Despite the increasing prevalence of heart failure with preserved ejection fraction (HFpEF) in humans, there remains no evidence-based therapies for HFpEF. Endothelin-1 (ET-1) antagonists are a possibility because elevated ET-1 levels are associated with adverse cardiovascular effects, such as arterial and pulmonary vasoconstriction, impaired left ventricular (LV) relaxation, and stimulation of LV hypertrophy. LV hypertrophy is a common phenotype in HFpEF, particularly when associated with hypertension. In the present study, we found that ET-1 levels were significantly elevated in patients with chronic stable HFpEF. We then sought to investigate the effects of chronic macitentan, a dual ET-A/ET-B receptor antagonist, on cardiac structure and function in a murine model of HFpEF induced by chronic aldosterone infusion. Macitentan caused LV hypertrophy regression independent of blood pressure changes in HFpEF. Although macitentan did not modulate diastolic dysfunction in HFpEF, it significantly reduced wall thickness and relative wall thickness after 2 weeks of therapy. In vitro studies showed that macitentan decreased the aldosterone-induced cardiomyocyte hypertrophy. These changes were mediated by a reduction in the expression of cardiac myocyte enhancer factor 2a. Moreover, macitentan improved adverse cardiac remodeling, by reducing the stiffer cardiac collagen I and titin n2b expression in the left ventricle of mice with HFpEF. These findings indicate that dual ET-A/ET-B receptor inhibition improves HFpEF by abrogating adverse cardiac remodeling via antihypertrophic mechanisms and by reducing stiffness. Additional studies are needed to explore the role of dual ET-1 receptor antagonists in patients with HFpEF. © 2016 American Heart Association, Inc.

  19. Differential effects of beta-adrenergic receptor blockade in the medial prefrontal cortex during aversive and incidental taste memory formation.

    PubMed

    Reyes-López, J; Nuñez-Jaramillo, L; Morán-Guel, E; Miranda, M I

    2010-08-11

    The medial prefrontal cortex (mPFC) is a brain area crucial for memory, attention, and decision making. Specifically, the noradrenergic system in this cortex is involved in aversive learning, as well as in the retrieval of these memories. Some evidence suggests that this area has an important role during taste memory, particularly during conditioned taste aversion (CTA), a model of aversive memory. Despite some previous evidence, there is scarce information about the role of adrenergic receptors in the mPFC during formation of aversive taste memory and appetitive/incidental taste memory. The goal of this research was to evaluate the role of mPFC beta-adrenergic receptors during CTA acquisition/consolidation or CTA retrieval, as well as during incidental taste memory formation using the model of latent inhibition of CTA. The results showed that infusions in the mPFC of the beta-adrenergic antagonist propranolol before CTA acquisition impaired both short- and long-term aversive taste memory formation, and also that propranolol infusions before the memory test impaired CTA retrieval. However, propranolol infusions before pre-exposure to the taste during the latent inhibition procedure had no effect on incidental taste memory acquisition or consolidation. These data indicate that beta-adrenergic receptors in the mPFC have different functions during taste memory formation: they have an important role during aversive taste association as well as during aversive retrieval but not during incidental taste memory formation. Copyright (c) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

  20. Dual Endothelin-A/Endothelin-B Receptor Blockade and Cardiac Remodeling in Heart Failure With Preserved Ejection Fraction

    PubMed Central

    Valero-Munoz, Maria; Li, Shanpeng; Wilson, Richard M.; Boldbaatar, Batbold; Iglarz, Marc; Sam, Flora

    2017-01-01

    Background Despite the increasing prevalence of heart failure with preserved ejection fraction (HFpEF) in humans, there remains no evidence-based therapies for HFpEF. Endothelin-1 (ET-1) antagonists are a possibility because elevated ET-1 levels are associated with adverse cardiovascular effects, such as arterial and pulmonary vasoconstriction, impaired left ventricular (LV) relaxation, and stimulation of LV hypertrophy. LV hypertrophy is a common phenotype in HFpEF, particularly when associated with hypertension. Methods and Results In the present study, we found that ET-1 levels were significantly elevated in patients with chronic stable HFpEF. We then sought to investigate the effects of chronic macitentan, a dual ET-A/ET-B receptor antagonist, on cardiac structure and function in a murine model of HFpEF induced by chronic aldosterone infusion. Macitentan caused LV hypertrophy regression independent of blood pressure changes in HFpEF. Although macitentan did not modulate diastolic dysfunction in HFpEF, it significantly reduced wall thickness and relative wall thickness after 2 weeks of therapy. In vitro studies showed that macitentan decreased the aldosterone-induced cardiomyocyte hypertrophy. These changes were mediated by a reduction in the expression of cardiac myocyte enhancer factor 2a. Moreover, macitentan improved adverse cardiac remodeling, by reducing the stiffer cardiac collagen I and titin n2b expression in the left ventricle of mice with HFpEF. Conclusions These findings indicate that dual ET-A/ET-B receptor inhibition improves HFpEF by abrogating adverse cardiac remodeling via antihypertrophic mechanisms and by reducing stiffness. Additional studies are needed to explore the role of dual ET-1 receptor antagonists in patients with HFpEF. PMID:27810862

  1. Nitrosative stress uncovers potent β2-adrenergic receptor-linked vasodilation further enhanced by blockade of clathrin endosome formation.

    PubMed

    Frame, Mary D; Dewar, Anthony M; Calizo, Rhodora C; Qifti, Androniqi; Scarlata, Suzanne F

    2018-06-01

    This study investigated the effect of sodium nitroprusside (SNP) preexposure on vasodilation via the β-adrenergic receptor (BAR) system. SNP was used as a nitrosative/oxidative proinflammatory insult. Small arterioles were visualized by intravital microscopy in the hamster cheek pouch tissue (isoflurane, n = 45). Control dilation to isoproterenol (EC 50 : 10 -7 mol/l) became biphasic as a function of concentration after 2 min of exposure to SNP (10 -4 M), with increased potency at picomolar dilation uncovered and decreased efficacy at the micromolar dilation. Control dilation to curcumin was likewise altered after SNP, but only the increased potency at a low dose was uncovered, whereas micromolar dilation was eliminated. The picomolar dilations were blocked by the potent BAR-2 inverse agonist carazolol (10 -9 mol/l). Dynamin inhibition with dynasore mimicked this effect, suggesting that SNP preexposure prevented BAR agonist internalization. Using HeLa cells transfected with BAR-2 tagged with monomeric red fluorescent protein, exposure to 10 -8 -10 -6 mol/l curcumin resulted in internalization and colocalization of BAR-2 and curcumin (FRET) that was prevented by oxidative stress (10 -3 mol/l CoCl 2 ), supporting that stress prevented internalization of the BAR agonist with the micromolar agonist. This study presents novel data supporting that distinct pools of BARs are differentially available after inflammatory insult. NEW & NOTEWORTHY Preexposure to an oxidative/nitrosative proinflammatory insult provides a "protective preconditioning" against future oxidative damage. We examined immediate vasoactive and molecular consequences of a brief preexposure via β-adrenergic receptor signaling in small arterioles. Blocked receptor internalization with elevated reactive oxygen levels coincides with a significant and unexpected vasodilation to β-adrenergic agonists at picomolar doses.

  2. Inverse agonism at the P2Y12 receptor and ENT1 transporter blockade contribute to platelet inhibition by ticagrelor.

    PubMed

    Aungraheeta, Riyaad; Conibear, Alexandra; Butler, Mark; Kelly, Eamonn; Nylander, Sven; Mumford, Andrew; Mundell, Stuart J

    2016-12-08

    Ticagrelor is a potent antagonist of the P2Y 12 receptor (P2Y 12 R) and consequently an inhibitor of platelet activity effective in the treatment of atherothrombosis. Here, we sought to further characterize its molecular mechanism of action. Initial studies showed that ticagrelor promoted a greater inhibition of adenosine 5'-diphosphate (ADP)-induced Ca 2+ release in washed platelets vs other P2Y 12 R antagonists. This additional effect of ticagrelor beyond P2Y 12 R antagonism was in part as a consequence of ticagrelor inhibiting the equilibrative nucleoside transporter 1 (ENT1) on platelets, leading to accumulation of extracellular adenosine and activation of G s -coupled adenosine A 2A receptors. This contributed to an increase in basal cyclic adenosine monophosphate (cAMP) and vasodilator-stimulated phosphoprotein phosphorylation (VASP-P). In addition, ticagrelor increased platelet cAMP and VASP-P in the absence of ADP in an adenosine receptor-independent manner. We hypothesized that this increase originated from a direct effect on basal agonist-independent P2Y 12 R signaling, and this was validated in 1321N1 cells stably transfected with human P2Y 12 R. In these cells, ticagrelor blocked the constitutive agonist-independent activity of the P2Y 12 R, limiting basal G i -coupled signaling and thereby increasing cAMP levels. These data suggest that ticagrelor has the pharmacological profile of an inverse agonist. Based on our results showing insurmountable inhibition of ADP-induced Ca 2+ release and forskolin-induced cAMP, the mode of antagonism of ticagrelor also appears noncompetitive, at least functionally. In summary, our studies describe 2 novel modes of action of ticagrelor, inhibition of platelet ENT1 and inverse agonism at the P2Y 12 R that contribute to its effective inhibition of platelet activation. © 2016 by The American Society of Hematology.

  3. Long-term orexigenic effects of AgRP-(83---132) involve mechanisms other than melanocortin receptor blockade.

    PubMed

    Hagan, M M; Rushing, P A; Pritchard, L M; Schwartz, M W; Strack, A M; Van Der Ploeg, L H; Woods, S C; Seeley, R J

    2000-07-01

    Overexpression of agouti-related peptide (AgRP), an endogenous melanocortin (MC) 3 and 4 receptor antagonist (MC3/4-R), causes obesity. Exogenous AgRP-(83---132) increases food intake, but its duration and mode of action are unknown. We report herein that doses as low as 10 pmol can have a potent effect on food intake of rats over a 24-h period after intracerebroventricular injection. Additionally, a single third ventricular dose as low as 100 pmol in rats produces a robust increase in food intake that persists for an entire week. AgRP-(83---132) completely blocks the anorectic effect of MTII (MC3/4-R agonist), given simultaneously, consistent with a competitive antagonist action. However, when given 24 h prior to MTII, AgRP-(83---132) is ineffective at reversing the anorectic effects of the agonist. These results support a critical role of MC tone in limiting food intake and indicate that the orexigenic effects of AgRP-(83---132) are initially mediated by competitive antagonism at MC receptors but are sustained by alternate mechanisms.

  4. 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.

  5. Lifelong disturbance of serotonin transporter functioning results in fear learning deficits: Reversal by blockade of CRF1 receptors.

    PubMed

    Bijlsma, Elisabeth Y; Hendriksen, Hendrikus; Baas, Johanna M P; Millan, Mark J; Groenink, Lucianne

    2015-10-01

    The inability to associate aversive events with relevant cues (i.e. fear learning) may lead to maladaptive anxiety. To further study the role of the serotonin transporter (SERT) in fear learning, classical fear conditioning was studied in SERT knockout rats (SERT(-/-)) using fear potentiation of the startle reflex. Next, fear acquisition and concomitant development of contextual conditioned fear were monitored during training. To differentiate between developmental and direct effects of reduced SERT functioning, effects of acute and chronic SSRI treatment were studied in adult rats. Considering the known interactions between serotonin and corticotropin-releasing factor (CRF), we studied the effect of the CRFR1 antagonist CP154,526 on behavioral changes observed and determined CRF1 receptor levels in SERT(-/-) rats. SERT(-/-) showed blunted fear potentiation and enhanced contextual fear, which resulted from a deficit in fear acquisition. Paroxetine treatment did not affect acquisition or expression of fear-potentiated startle, suggesting that disturbed fear learning in SERT(-/-) results from developmental changes and not from reduced SERT functioning. Although CRF1 receptor levels did not differ significantly between genotypes, CP154,526 treatment normalized both cue- and contextual fear in SERT(-/-) during acquisition, but not expression of fear-potentiated startle. The disrupted fear acquisition and concomitant increase in contextual conditioned fear-potentiated startle fear in SERT(-/-) resembles the associative learning deficit seen in patients with panic disorder and suggests that normal SERT functioning is crucial for the development of an adequate fear neuro-circuitry. Moreover, the normalization of fear acquisition by CP154,526 suggests a role for central CRF signaling in the generalization of fear. Copyright © 2015 Elsevier B.V. and ECNP. All rights reserved.

  6. 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

  7. Contrasting Effects of Lithium Chloride and CB1 Receptor Blockade on Enduring Changes in the Valuation of Reward.

    PubMed

    Hernandez, Giovanni; Bernstein, David; Schoenbaum, Geoffrey; Cheer, Joseph F

    2011-01-01

    When an organism responds for a reward, its learned behavior can be characterized as goal-directed or habitual based on whether or not it is susceptible to reward devaluation. Here, we evaluated whether instrumental responding for brain stimulation reward (BSR) can be devalued using a paradigm traditionally used for natural rewards. Rats were trained to lever press for BSR; afterward, BSR was paired with either lithium chloride (LiCl, 5 mg/kg, i.p.), a pro-emetic, or AM251, a CB1 receptor antagonist (3 mg/kg, i.p.) or the vehicle of these compounds. Pairings of BSR with these compounds and their vehicles were performed in a novel environment so that only unconditional effects of BSR would be affected by the pharmacological manipulations. Subsequently, in a probe test, all rats were returned in the drug-free state to the boxes where they had received training and instrumental responding was reassessed in the absence of BSR delivery. When compared to control, LiCl produced a significant decrease in the number of responses during the test session, whereas AM251 did not. These results show that instrumental responding for BSR is susceptible to devaluation, in accord with the proposal that this behavior is supported at least in part by associations between the response and the rewarding outcome. Further, they suggest that reward modulation observed in studies involving the use of CB1 receptor antagonists arises from changes in the organism's motivation rather than drug-induced changes in the intrinsic value of reward.

  8. Selective stimulation and blockade of beta-adrenergic receptors in the mandibular gland of the red kangaroo, Macropus rufus.

    PubMed

    Beal, A M

    2000-12-01

    Intracarotid infusions of noradrenaline (0.15 nmol x kg(-1) x min(-1)) either alone or accompanied by phentolamine (1.5 nmol x kg(-1) x min(-1)) caused similar-sized increases in salivary protein, magnesium and bicarbonate, and decreases in osmolality, sodium, potassium and chloride whereas intravenous noradrenaline stimulated much smaller responses. Concurrent infusions of the beta1-antagonist, CGP20712A, blocked these noradrenaline-induced changes in salivary composition more effectively than equimolar infusions of the beta2-antagonist, ICI118551, thereby confirming the presence of beta1-adrenoceptors. Intracarotid infusion of salbutamol at 0.15, 0.3 and 1.5 nmol x kg(-1) x min(-1) caused increasing but qualitatively similar changes in salivary composition, sodium excepted, to intracarotid noradrenaline with 0.3 nmol being most similar quantitatively. Intravenous infusion of salbutamol caused larger changes in salivary composition than equimolar intravenous noradrenaline thereby indicating that the response to salbutamol may, in part, be mediated by reflex increases in general sympathetic tone triggered by lowered blood pressure. Eliminating this hypotensive effect by concurrent intravenous and intracarotid infusions of beta1-(CGP or atenolol) and beta2-(ICII18551) antagonists with intracarotid salbutamol showed that IC1118551 was more potent than the beta1-antagonists thereby demonstrating the presence of beta2-receptors. It was concluded that the kangaroo mandibular has functional beta1- and beta2-adrenoceptor subtypes in both endpieces and excurrent ducts and that the duct system has two populations of cells, each expressing one receptor subtype.

  9. 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.

  10. Effects of targeted deletion of A1 adenosine receptors on postischemic cardiac function and expression of adenosine receptor subtypes.

    PubMed

    Morrison, R Ray; Teng, Bunyen; Oldenburg, Peter J; Katwa, Laxmansa C; Schnermann, Jurgen B; Mustafa, S Jamal

    2006-10-01

    To examine ischemic tolerance in the absence of A(1) adenosine receptors (A(1)ARs), isolated wild-type (WT) and A(1)AR knockout (A(1)KO) murine hearts underwent global ischemia-reperfusion, and injury was measured in terms of functional recovery and efflux of lactate dehydrogenase (LDH). Hearts were analyzed by real-time RT-PCR both at baseline and at intervals during ischemia-reperfusion to determine whether compensatory expression of other adenosine receptor subtypes occurs with either A(1)AR deletion and/or ischemia-reperfusion. A(1)KO hearts had higher baseline coronary flow (CF) and left ventricular developed pressure (LVDP) than WT hearts, whereas heart rate was unchanged by A(1)AR deletion. After 20 min of ischemia, CF was attenuated in A(1)KO compared with WT hearts, and this reduction persisted throughout reperfusion. Final recovery of LVDP was decreased in A(1)KO hearts (54.4 +/- 5.1 vs. WT 81.1 +/- 3.4% preischemic baseline) and correlated with higher diastolic pressure during reperfusion. Postischemic efflux of LDH was greater in A(1)KO compared with WT hearts. Real-time RT-PCR demonstrated the absence of A(1)AR transcript in A(1)KO hearts, and the message for A(2A), A(2B), and A(3) adenosine receptors was similar in uninstrumented A(1)KO and WT hearts. Ischemia-reperfusion increased A(2B) mRNA expression 2.5-fold in both WT and A(1)KO hearts without changing A(1) or A(3) expression. In WT hearts, ischemia transiently doubled A(2A) mRNA, which returned to preischemic level upon reperfusion, a pattern not observed in A(1)KO hearts. Together, these data affirm the cardioprotective role of A(1)ARs and suggest that induced expression of other adenosine receptor subtypes may participate in the response to ischemia-reperfusion in isolated murine hearts.

  11. Enhancing Effects of NMDA-Receptor Blockade on Extinction Learning and Related Brain Activation Are Modulated by BMI

    PubMed Central

    Golisch, Anne; Heba, Stefanie; Glaubitz, Benjamin; Tegenthoff, Martin; Lissek, Silke

    2017-01-01

    A distributed network including prefrontal and hippocampal regions is involved in context-related extinction learning as well as in renewal. Renewal describes the recovery of an extinguished response if the context of extinction differs from the context of recall. Animal studies have demonstrated that prefrontal, but not hippocampal N-methyl-D-aspartate receptor (NMDAR) antagonism disrupted extinction learning and processing of task context. However, human studies of NMDAR in extinction learning are lacking, while NMDAR antagonism yielded contradictory results in other learning tasks. This fMRI study investigated the role of NMDAR for human behavioral and brain activation correlates of extinction and renewal. Healthy volunteers received a single dose of the NMDAR antagonist memantine prior to extinction of previously acquired stimulus-outcome associations presented in either identical or novel contexts. We observed better, and partly faster, extinction learning in participants receiving the NMDAR antagonist compared to placebo. However, memantine did not affect renewal. In both extinction and recall, the memantine group showed a deactivation in extinction-related brain regions, particularly in the prefrontal cortex, while hippocampal activity was increased. This higher hippocampal activation was in turn associated with the participants' body mass index (BMI) and extinction errors. Our results demonstrate potentially dose-related enhancing effects of memantine and highlight involvement of hippocampal NMDAR in context-related extinction learning. PMID:28326025

  12. Testing synaptic plasticity in dynamic mate choice decisions: N-methyl d-aspartate receptor blockade disrupts female preference

    PubMed Central

    Ramsey, Mary E.; Vu, Wendy; Cummings, Molly E.

    2014-01-01

    Social behaviours such as mate choice require context-specific responses, often with evolutionary consequences. Increasing evidence indicates that the behavioural plasticity associated with mate choice involves learning. For example, poeciliids show age-dependent changes in female preference functions and express synaptic-plasticity-associated molecular markers during mate choice. Here, we test whether social cognition is necessary for female preference behaviour by blocking the central player in synaptic plasticity, NMDAR (N-methyl d-aspartate receptor), in a poeciliid fish, Xiphophorus nigrensis. After subchronic exposure to NMDAR antagonist MK-801, female preference behaviours towards males were dramatically reduced. Overall activity levels were unaffected, but there was a directional shift from ‘social’ behaviours towards neutral activity. Multivariate gene expression patterns significantly discriminated between females with normal versus disrupted plasticity processes and correlated with preference behaviours—not general activity. Furthermore, molecular patterns support a distinction between ‘preference’ (e.g. neuroserpin, neuroligin-3, NMDAR) and ‘sociality’ (isotocin and vasotocin) gene clusters, highlighting a possible conservation between NMDAR disruption and nonapeptides in modulating behaviour. Our results suggest that mate preference may involve greater social memory processing than overall sociality, and that poeciliid preference functions integrate synaptic-plasticity-oriented ‘preference’ pathways with overall sociality to invoke dynamic, context-specific responses towards favoured males and away from unfavoured males. PMID:24807251

  13. Effects of dopamine D1 receptor blockade in the prelimbic prefrontal cortex or lateral dorsal striatum on frontostriatal function in Wistar and Spontaneously Hypertensive Rats.

    PubMed

    Gauthier, Jamie M; Tassin, David H; Dwoskin, Linda P; Kantak, Kathleen M

    2014-07-15

    Attention Deficit Hyperactivity Disorder (ADHD) is associated with dysfunctional prefrontal and striatal circuitry and dysregulated dopamine neurotransmission. Spontaneously Hypertensive Rats (SHR), a heuristically useful animal model of ADHD, were evaluated against normotensive Wistar (WIS) controls to determine whether dopamine D1 receptor blockade of either prelimbic prefrontal cortex (plPFC) or lateral dorsal striatum (lDST) altered learning functions of both interconnected sites. A strategy set shifting task measured plPFC function (behavioral flexibility/executive function) and a reward devaluation task measured lDST function (habitual responding). Prior to tests, rats received bilateral infusions of SCH 23390 (1.0 μg/side) or vehicle into plPFC or lDST. Following vehicle, SHR exhibited longer lever press reaction times, more trial omissions, and fewer completed trials during the set shift test compared to WIS, indicating slower decision-making and attentional/motivational impairment in SHR. After reward devaluation, vehicle-treated SHR responded less than WIS, indicating relatively less habitual responding in SHR. After SCH 23390 infusions into plPFC, WIS expressed the same behavioral phenotype as vehicle-treated SHR during set shift and reward devaluation tests. In SHR, SCH 23390 infusions into plPFC exacerbated behavioral deficits in the set shift test and maintained the lower rate of responding in the reward devaluation test. SCH 23390 infusions into lDST did not modify set shifting in either strain, but produced lower rates of responding than vehicle infusions after reward devaluation in WIS. This research provides pharmacological evidence for unidirectional interactions between prefrontal and striatal brain regions, which has implications for the neurological basis of ADHD and its treatment. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Blockade of dopamine D2 receptors disrupts intrahippocampal connectivity and enhances pain-related working memory deficits in neuropathic pain rats.

    PubMed

    Cardoso-Cruz, H; Dourado, M; Monteiro, C; Galhardo, V

    2018-05-01

    Dopamine (DA) is thought to be important to local hippocampal networks integrity during spatial working memory (sWM) processing. Chronic pain may contribute to deficient dopaminergic signalling, which may in turn affect cognition. However, the neural mechanisms that determine this impairment are poorly understood. Here, we evaluated whether the sWM impairment characteristic of animal models of chronic pain is dependent on DA D2 receptor (D2r) activity. To address this issue, we implanted multichannel arrays of electrodes in the dorsal and ventral hippocampal CA1 field (dvCA1) of rats and recorded the neuronal activity during a classical delayed food-reinforced T-maze sWM task. Within-subject behavioural performance and patterns of dorsoventral neural activity were assessed before and after the onset of persistent neuropathic pain using the spared nerve injury (SNI) model. Our results show that the peripheral nerve lesion caused a disruption in sWM and hippocampus spike activity and that disruption was maximized by the systemic administration of the D2r antagonist raclopride. These deficits are strictly correlated with a selective disruption of hippocampal theta-oscillations. Particularly, we found a significant decrease in intrahippocampal CA1 field connectivity level. Together, these results suggest that disruption of the dopaminergic balance in the intrahippocampal networks may be important for the development of cognitive deficits experienced during painful conditions. This study provides new insights into the role of D2r in the manifestation of pain-related sWM deficits. Our findings support that selective blockade of D2r produces a significant decrease in intrahippocampal connectivity mediated by theta-oscillations, and amplifies pain-related sWM deficits. These results suggest that further characterization of intrahippocampal dopaminergic modulation may be clinically relevant for the understanding of cognitive impairments that accompanies nociceptive

  15. Interaction of the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) and opioid receptors in spinal cord nociceptive reflexes.

    PubMed

    Ramos-Zepeda, Guillermo; Herrero, Juan F

    2013-08-14

    We previously observed that the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) is a very effective antinociceptive agent on intact but not on spinalized adult rats with inflammation. Since a close connection between opioid and adenosine A1 receptors has been described, we studied a possible relationship between these systems in the spinal cord. CPA-mediated antinociception was challenged by the selective adenosine A1 receptor antagonist 8-cyclopentyl-1, 3-dimethylxanthine (CPT) and by the opioid receptor antagonist naloxone on male adult Wistar rats with carrageenan-induced inflammation. Withdrawal reflexes activated by noxious mechanical and electrical stimulation were recorded using the single motor technique in intact and sham-spinalized animals. CPA was very effective in intact and sham spinalized rats but not in spinalized animals. Full reversal of CPA antinociception was observed with i.v. 1mg/kg of naloxone but not with 20mg/kg of CPT i.v. in responses to noxious mechanical and electrical stimulation. CPT fully prevented CPA from any antinociceptive action whereas naloxone did not modify CPA activity. These results suggest a centrally-mediated action, since CPA depressed the wind-up phenomenon which is derived of the activity of spinal cord neurons. The present study provides strong in vivo evidence of an antinociceptive activity mediated by the adenosine A1 receptor system in the spinal cord, linked to an activation of opioid receptors in adult animals with inflammation. © 2013.

  16. CRF receptor blockade prevents initiation and consolidation of stress effects on affect in the predator stress model of PTSD.

    PubMed

    Adamec, Robert; Fougere, Dennis; Risbrough, Victoria

    2010-07-01

    Post traumatic stress disorder (PTSD) is a chronic anxiety disorder initiated by an intensely threatening, traumatic event. There is a great need for more efficacious pharmacotherapy and preventive treatments for PTSD. In animals, corticotropin-releasing factor (CRF) and the CRF1 receptor play a critical role in behavioural and neuroendocrine responses to stress. We tested the hypothesis that CRF1 activation is required for initiation and consolidation of long-term effects of trauma on anxiety-like behaviour in the predator exposure (predator stress) model of PTSD. Male C57BL6 mice were treated with the selective CRF1 antagonist CRA0450 (2, 20 mg/kg) 30 min before or just after predator stress. Long-term effects of stress on rodent anxiety were measured 7 d later using acoustic startle, elevated plus maze (EPM), light/dark box, and hole-board tests. Predator stress increased startle amplitude and delayed startle habituation, increased time in and decreased exits from the dark chamber in the light/dark box test, and decreased risk assessment in the EPM. CRF1 antagonism had limited effects on these behaviours in non-stressed controls, with the high dose decreasing risk assessment in the EPM. However, in stressed animals CRF1 antagonism blocked initiation and consolidation of stressor effects on startle, and returned risk assessment to baseline levels in predator-stressed mice. These findings implicate CRF1 activation in initiation and post-trauma consolidation of predator stress effects on anxiety-like behaviour, specifically on increased arousal as measured by exaggerated startle behaviours. These data support further research of CRF1 antagonists as potential prophylactic treatments for PTSD.

  17. Enhanced tumor metastasis in response to blockade of the chemokine receptor CXCR6 is overcome by NKT cell activation.

    PubMed

    Cullen, Robyn; Germanov, Elitza; Shimaoka, Takeshi; Johnston, Brent

    2009-11-01

    Invariant NKT (iNKT) cells can induce potent antitumor responses in vivo. However, the mechanisms that regulate the effects of iNKT cells are unclear. The chemokine receptor CXCR6, and its ligand CXCL16, have been shown to play critical roles in iNKT cell homeostasis and activation. Thus we investigated the role of CXCR6 in protection against experimental metastasis of B16-F10 melanoma (B16) and Lewis lung carcinoma (LLC) cells to the liver and lungs. Wild-type and CXCR6(-/-) mice exhibited no differences in tumor cell metastasis to the lungs. However, metastasis of LLC and B16 tumor cells to the liver was enhanced in CXCR6(-/-) mice. Liver metastasis was also increased in wild-type mice treated with a CXCL16 neutralizing Ab. As Ab treatments did not alter iNKT cell numbers, this implicates a direct role for CXCR6/CXCL16 in regulating antitumor immunity. Cytokine induction was significantly attenuated in CXCR6(-/-) mice upon systemic iNKT cell activation with the glycolipid Ags alpha-galactosylceramide (alpha-GalCer), alpha-C-GalCer (a Th1 polarizing derivative), or OCH (a Th2 polarizing derivative). Despite differences in the levels of cytokine production, liver and lung metastasis were inhibited significantly in both wild-type and CXCR6(-/-) mice treated with glycolipids. Single doses of alpha-GalCer, alpha-C-GalCer, or OCH were sufficient to prevent liver metastasis and subsequent doses failed to elicit optimal cytokine responses. Our findings implicate a role for CXCR6 in natural immunosurveillance against liver metastasis. However, CXCR6 deficiency could be overcome by systemic iNKT cell activation, demonstrating that even suboptimal iNKT cell activation can protect against metastasis.

  18. [The effects of selective 5HT3 receptor blockade on physiological markers of abdominal pain in awake dogs].

    PubMed

    Panteleev, S S; Busygina, I I; Liubashina, O A

    2013-04-01

    In awake dogs, the visceromotor and cardioautonomic responses to the rectal balloon distension were studied before and after intravenous administration of a selective 5HT3 receptor antagonist granisetron. It was shown that balloon distension level up to 60 mmHg caused neither noticeable muscle responses nor substantial changes in heart rate. In turn, distending pressures of 80 mmHg and higher induced vigorous abdominal muscle contractions and tachycardia that were graded with increasing intensities of stimulation. Thus, the rectal stimulation with pressures 80 mmHg and more produced the changes in visceromotor and cardiovascular indices which could be considered as suitable indicators of visceral nociception in conscious animals. Based on monitoring of these physiological markers in a model of abdominal pain the dose-dependent antinociceptive effect of granisetron in awake dogs has been demonstrated for the first time. It was determined that granisetron in doses of 0.25, 0.5 or 1.0 mg/kg induced correspondingly 33.6 +/- 9.2, 58.0+/- 8.6 [see text] 76.7 +/- 5.5 % decrease in visceromotor response of dogs to nociceptive visceral stimulation. The effect occurred immediately after the drug administration and was lasting more than 90 min. In turn, the dose-dependent suppression of the rectal distension-induced tachycardia was less prominent and only observed during the initial period of granisetron action. The described model of abdominal pain in awake dogs might be useful for preclinical screening of new pharmacological substances, whereas the obtained data could contribute to the development of more efficient analgesics aimed in patients with irritable bowel syndrome.

  19. M1 muscarinic receptor facilitates cognitive function by interplay with AMPA receptor GluA1 subunit.

    PubMed

    Zhao, Lan-Xue; Ge, Yan-Hui; Xiong, Cai-Hong; Tang, Ling; Yan, Ying-Hui; Law, Ping-Yee; Qiu, Yu; Chen, Hong-Zhuan

    2018-03-06

    M1 muscarinic acetylcholine receptors (M1 mAChRs) are the most abundant muscarinic receptors in the hippocampus and have been shown to have procognitive effects. AMPA receptors (AMPARs), an important subtype of ionotropic glutamate receptors, are key components in neurocognitive networks. However, the role of AMPARs in procognitive effects of M1 mAChRs and how M1 mAChRs affect the function of AMPARs remain poorly understood. Here, we found that basal expression of GluA1, a subunit of AMPARs, and its phosphorylation at Ser845 were maintained by M1 mAChR activity. Activation of M1 mAChRs promoted membrane insertion of GluA1, especially to postsynaptic densities. Impairment of hippocampus-dependent learning and memory by antagonism of M1 mAChRs paralleled the reduction of GluA1 expression, and improvement of learning and memory by activation of M1 mAChRs was accompanied by the synaptic insertion of GluA1 and its increased phosphorylation at Ser845. Furthermore, abrogation of phosphorylation of Ser845 residue of GluA1 ablated M1 mAChR-mediated improvement of learning and memory. Taken together, these results show a functional correlation of M1 mAChRs and GluA1 and the essential role of GluA1 in M1 mAChR-mediated cognitive improvement.-Zhao, L.-X., Ge, Y.-H., Xiong, C.-H., Tang, L., Yan, Y.-H., Law, P.-Y., Qiu, Y., Chen, H.-Z. M1 muscarinic receptor facilitates cognitive function by interplay with AMPA receptor GluA1 subunit.

  20. Effect of early versus late AT(1) receptor blockade with losartan on postmyocardial infarction ventricular remodeling in rabbits.

    PubMed

    González, Germán E; Seropian, Ignacio M; Krieger, Maria Laura; Palleiro, Jimena; Lopez Verrilli, Maria A; Gironacci, Mariela M; Cavallero, Susana; Wilensky, Luciana; Tomasi, Victor H; Gelpi, Ricardo J; Morales, Celina

    2009-07-01

    To characterize the temporal activation of the renin-angiotensin system after myocardial infarction (MI) in rabbits, we examined cardiac ANG II type 1 receptor (AT(1)R) expression and ANG II levels from 3 h to 35 days. The effects of losartan (12.5 mg.kg(-1).day(-1)) on functional and histomorphometric parameters when treatment was initiated early (3 h) and late (day 15) post-MI and maintained for different periods of time [short term (4 days), midterm (20 days), and long term (35 days)] were also studied. AT(1)R expression increased in the MI zone at 15 and 35 days (P < 0.05). ANG II levels increased (P < 0.05) in the non-MI zone at 24 h and in the MI zone as well as in plasma at 4 days and then progressively decreased until 35 days. The survival rate was significantly lower in untreated MI and early long-term-treated animals. Diastolic pressure-volume curves in MI at 35 and 56 days shifted to the right (P < 0.05). This shift was even more pronounced in long-term-treated groups (P < 0.05). Contractility decreased (P < 0.05 vs. sham) in the untreated and long-term-treated groups and was attenuated in the midterm-treated group. The early administration of losartan reduced RAM 11-positive macrophages from 4.15 +/- 0.05 to 3.05 +/- 0.02 cells/high-power field (HPF; P < 0.05) and CD45 RO-positive lymphocytes from 2.23 +/- 0.05 to 1.48 +/- 0.01 cells/HPF (P < 0.05) in the MI zone at 4 days. Long-term treatment reduced the scar collagen (MI: 70.50 +/- 2.35% and MI + losartan: 57.50 +/- 2.48, P < 0.05), determined the persistency of RAM 11-positive macrophages (3.02 +/- 0.13 cells/HPF) and CD45 RO-positive lymphocytes (2.77 +/- 0.58 cells/HPF, P < 0.05 vs. MI), and reduced the scar thinning ratio at 35 days (P < 0.05). Consequently, the temporal expressions of cardiac AT(1)R and ANG II post-MI in rabbits are different from those described in other species. Long-term treatment unfavorably modified post-MI remodeling, whereas midterm treatment attenuated this harmful effect

  1. AT1-AA (Angiotensin II Type 1 Receptor Agonistic Autoantibody) Blockade Prevents Preeclamptic Symptoms in Placental Ischemic Rats.

    PubMed

    Cunningham, Mark W; Castillo, Javier; Ibrahim, Tarek; Cornelius, Denise C; Campbell, Nathan; Amaral, Lorena; Vaka, Venkata Ramana; Usry, Nathan; Williams, Jan M; LaMarca, Babbette

    2018-05-01

    Women with preeclampsia produce AT1-AA (agonistic autoantibodies to the angiotensin II type 1 receptor), which stimulate reactive oxygen species, inflammatory factors, and hypertensive mechanisms (ET [endothelin] and sFlt-1 [soluble fms-like tyrosine kinase-1]) in rodent models of preeclampsia. The placental ischemic reduced uterine perfusion pressure (RUPP) rat model of preeclampsia exhibits many of these features. In this study, we examined the maternal outcomes of AT1-AA inhibition ('n7AAc') in RUPP rats. Blood pressure was higher in RUPP rats versus normal pregnant (NP) rats (123±2 versus 99±2 mm Hg, P <0.05), which was reduced in RUPP+'n7AAc' (105±3 versus 123±2 mm Hg, P <0.05 versus RUPP). Uterine artery resistant index was increased in RUPP versus NP rats (0.71±0.02 versus 0.49±0.02, P <0.05) and normalized in RUPP+'n7AAc' rats (0.55±0.03). Antiangiogenic factor sFlt-1 was elevated in RUPP versus NP rats (176±37 versus 77±15 pg/mL, P <0.05) but normalized in RUPP+'n7AAc' (86±9, P =0.05 versus RUPP). Plasma nitrate and nitrite were decreased (14±1 versus 20±1 µMNO 3 , P <0.05) and isoprostanes were elevated (20 117±6304 versus 2809±1375 pg/mL, P <0.05) in RUPP versus NP rats; and normalized in RUPP+'n7AAc' rats; (18±2 µMNO 3 ; 4311±1 pg/mL). PPET-1 (preproendothelin-1) expression increased 4-fold in RUPP versus NP rats which were prevented with 'n7AAc'. Importantly, placental cytolytic natural killer cells were elevated in RUPP versus NP rats (8±2% versus 2±2% gated, P <0.05), which was prevented in RUPP+'n7AAc' total (3±1% gated, P <0.05) In conclusion, AT1-AA inhibition prevents the rise in maternal blood pressure and several pathophysiological factors associated with preeclampsia in RUPP rats and could be a potential therapy for preeclampsia. © 2018 American Heart Association, Inc.

  2. Angiotensin Receptor Blockades Effect on Peripheral Muscular and Central Aortic Arterial Stiffness: A Meta-Analysis of Randomized Controlled Trials and Systematic Review.

    PubMed

    Yen, Chih-Hsuan; Lai, Yau-Huei; Hung, Chung-Lieh; Lee, Ping-Ying; Kuo, Jen-Yuan; Yeh, Hung-I; Hou, Charles Jia-Yin; Chien, Kuo-Liong

    2014-03-01

    Previous clinical trials have demonstrated the impact of blocking upstream renin-angiotensin-axis with angiotensin converting enzyme inhibitors (ACEIs) on arterial stiffness as evaluated by pulse-wave velocity (PWV). We ran a meta-analysis to evaluate the anti-stiffness effect of powerful downstream angiotensin receptor blockades (ARBs) on peripheral and central arterial stiffness (brachial to ankle, ba-PWV; carotid to femoral, cf-PWV, respectively), using a systematic review to assess the clinical arterial stiffness issues. For our study, we searched the PubMed and Cochrane Library databases from inception to June 2013, targeting randomized controlled trials. ARBs along with other antihypertensive agents, ACEIs, calcium channel blockers (CCBs), beta-blockers and diuretics were evaluated to ascertain their comparable effect on ba-PWV and cf-PWV, respectively. A meta-analysis was conducted utilizing the fixed or random effect of the weighted mean change difference between the ARB and comparator groups, depending on the I(2) statistic heterogeneity measurement. In 2 trials treating patients with ARBs (n = 30), the ARBs insignificantly reduced levels of ba-PWV (pooled mean change difference -188, 95% CI -687, 311, p = 0.24 with significant heterogeneity) as compared to other hypertensive agents (ACEIs and CCBs, n = 77). Interestingly, ARBs (n = 20) had a superior capacity to reduce levels of ba-PWV than CCBs (n = 20) in single study results (mean change difference -400, 95% CI -477, -322, p < 0.05). In 7 trials which included a total of 653 patients, treatment with ARBs (n = 308) also insignificantly reduced cf-PWV (pool mean change difference -0.197, 95% CI -0.54, 0.14, p = 0.218) as compared to other anti-hypertensive agents. Our data suggested that ARBs had a similar effect as other anti-hypertensive agents in reducing ba-PWV and cf-PWV. Upon systematic review, the renin-angiotensin-axis system mechanism seems more significant than the direct vessel dilatation

  3. 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

    SP bioavailability. When oxidative inactivation of NEP is prevented by SP receptor blockade, partial protection is afforded against cardiac contractile dysfunction.

  4. 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

    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

  5. Dynamic 123I-BMIPP single-photon emission computed tomography in patients with congestive heart failure: effect of angiotensin II type-1 receptor blockade.

    PubMed

    Takeishi, Yasuchika; Minamihaba, Osamu; Yamauchi, Sou; Arimoto, Takanori; Hirono, Osamu; Takahashi, Hiroki; Akiyama, Hideyuki; Miyamoto, Takuya; Nitobe, Joji; Nozaki, Naoki; Tachibana, Hidetada; Okuyama, Masaki; Fukui, Akio; Kubota, Isao; Okada, Akio; Takahashi, Kazuei

    2004-04-01

    Heart failure is a major and growing public health problem with a high mortality rate. Although recent studies have demonstrated that a variety of metabolic and/or neurohumoral factors are involved in the progression of this syndrome, the precise mechanisms responsible for this complex condition are poorly understood. To examine 123I-beta-methyl-iodophenylpentadecanoic acid (BMIPP) kinetics in the early phase soon after tracer injection in patients with congestive heart failure (CHF), we performed dynamic single-photon emission computed tomography (SPECT). Twenty-six patients with CHF and eight control subjects were examined. The consecutive 15 images of 2-min dynamic SPECT were acquired for 30 min after injection. In the early phase after injection (0-4 min), a significant amount of radioactivity existed in the blood pool. After 6 min, the myocardial 123I-BMIPP image was clear and thus the washout rate of 123I-BMIPP from 6 to 30 min was calculated. The washout rate of 123I-BMIPP from the myocardium was faster in patients with CHF than in the controls (8 +/- 4 vs. -5 +/- 3%, p < 0.01). The washout rate of 123I-BMIPP demonstrated positive correlation with left ventricular (LV) end-diastolic volume index (R = 0.54, p < 0.02) and inverse correlation with LV ejection fraction (R = 0.53, p <0.02). Patients were given the angiotensin II type-1 receptor antagonist candesartan for 6 months, and dynamic SPECT was repeated. The enhanced washout rate of 123I-BMIPP in CHF was reduced after treatment with candesartan (p < 0.05). These data suggest that (1) enhanced washout of 123I-BMIPP was observed soon after injection in patients with CHF, (2) the activation of angiotensin II signaling pathway is involved as an intracellular mechanism for enhanced 123I-BMIPP washout in heart failure, and (3) improvement in fatty acid metabolism may represent a new mechanism for beneficial effects of angiotensin II receptor blockade on cardiac function and survival in patients with heart

  6. Orphan nuclear receptor oestrogen-related receptor γ (ERRγ) plays a key role in hepatic cannabinoid receptor type 1-mediated induction of CYP7A1 gene expression

    PubMed Central

    Zhang, Yaochen; Kim, Don-Kyu; Lee, Ji-Min; Park, Seung Bum; Jeong, Won-IL; Kim, Seong Heon; Lee, In-Kyu; Lee, Chul-Ho; Chiang, John Y.L.; Choi, Hueng-Sik

    2017-01-01

    Bile acids are primarily synthesized from cholesterol in the liver and have important roles in dietary lipid absorption and cholesterol homoeostasis. Detailed roles of the orphan nuclear receptors regulating cholesterol 7α-hydroxylase (CYP7A1), the rate-limiting enzyme in bile acid synthesis, have not yet been fully elucidated. In the present study, we report that oestrogen-related receptor γ (ERRγ) is a novel transcriptional regulator of CYP7A1 expression. Activation of cannabinoid receptor type 1 (CB1 receptor) signalling induced ERRγ-mediated transcription of the CYP7A1 gene. Overexpression of ERRγ increased CYP7A1 expression in vitro and in vivo, whereas knockdown of ERRγ attenuated CYP7A1 expression. Deletion analysis of the CYP7A1 gene promoter and a ChIP assay revealed an ERRγ -binding site on the CYP7A1 gene promoter. Small heterodimer partner (SHP) inhibited the transcriptional activity of ERRγ and thus regulated CYP7A1 expression. Overexpression of ERRγ led to increased bile acid levels, whereas an inverse agonist of ERRγ, GSK5182, reduced CYP7A1 expression and bile acid synthesis. Finally, GSK5182 significantly reduced hepatic CB1 receptor-mediated induction of CYP7A1 expression and bile acid synthesis in alcohol-treated mice. These results provide the molecular mechanism linking ERRγ and bile acid metabolism. PMID:26348907

  7. Neonatal NMDA Receptor Blockade Disrupts Spike Timing and Glutamatergic Synapses in Fast Spiking Interneurons in a NMDA Receptor Hypofunction Model of Schizophrenia

    PubMed Central

    Jones, Kevin S.; Corbin, Joshua G.; Huntsman, Molly M.

    2014-01-01

    The dysfunction of parvalbumin-positive, fast-spiking interneurons (FSI) is considered a primary contributor to the pathophysiology of schizophrenia (SZ), but deficits in FSI physiology have not been explicitly characterized. We show for the first time, that a widely-employed model of schizophrenia minimizes first spike latency and increases GluN2B-mediated current in neocortical FSIs. The reduction in FSI first-spike latency coincides with reduced expression of the Kv1.1 potassium channel subunit which provides a biophysical explanation for the abnormal spiking behavior. Similarly, the increase in NMDA current coincides with enhanced expression of the GluN2B NMDA receptor subunit, specifically in FSIs. In this study mice were treated with the NMDA receptor antagonist, MK-801, during the first week of life. During adolescence, we detected reduced spike latency and increased GluN2B-mediated NMDA current in FSIs, which suggests transient disruption of NMDA signaling during neonatal development exerts lasting changes in the cellular and synaptic physiology of neocortical FSIs. Overall, we propose these physiological disturbances represent a general impairment to the physiological maturation of FSIs which may contribute to schizophrenia-like behaviors produced by this model. PMID:25290690

  8. Antinociception by systemically-administered acetaminophen (paracetamol) involves spinal serotonin 5-HT7 and adenosine A1 receptors, as well as peripheral adenosine A1 receptors.

    PubMed

    Liu, Jean; Reid, Allison R; Sawynok, Jana

    2013-03-01

    Acetaminophen (paracetamol) is a widely used analgesic, but its sites and mechanisms of action remain incompletely understood. Recent studies have separately implicated spinal adenosine A(1) receptors (A(1)Rs) and serotonin 5-HT(7) receptors (5-HT(7)Rs) in the antinociceptive effects of systemically administered acetaminophen. In the present study, we determined whether these two actions are linked by delivering a selective 5-HT(7)R antagonist to the spinal cord of mice and examining nociception using the formalin 2% model. In normal and A(1)R wild type mice, antinociception by systemic (i.p.) acetaminophen 300mg/kg was reduced by intrathecal (i.t.) delivery of the selective 5-HT(7)R antagonist SB269970 3μg. In mice lacking A(1)Rs, i.t. SB269970 did not reverse antinociception by systemic acetaminophen, indicating a link between spinal 5-HT(7)R and A(1)R mechanisms. We also explored potential roles of peripheral A(1)Rs in antinociception by acetaminophen administered both locally and systemically. In normal mice, intraplantar (i.pl.) acetaminophen 200μg produced antinociception in the formalin test, and this was blocked by co-administration of the selective A(1)R antagonist DPCPX 4.5μg. Acetaminophen administered into the contralateral hindpaw had no effect, indicating a local peripheral action. When acetaminophen was administered systemically, its antinociceptive effect was reversed by i.pl. DPCPX in normal mice; this was also observed in A(1)R wild type mice, but not in those lacking A(1)Rs. In summary, we demonstrate a link between spinal 5-HT(7)Rs and A(1)Rs in the spinal cord relevant to antinociception by systemic acetaminophen. Furthermore, we implicate peripheral A(1)Rs in the antinociceptive effects of locally- and systemically-administered acetaminophen. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  9. Actions of novel antipsychotic agents on apomorphine-induced PPI disruption: influence of combined serotonin 5-HT1A receptor activation and dopamine D2 receptor blockade.

    PubMed

    Auclair, Agnès L; Kleven, Mark S; Besnard, Joël; Depoortère, Ronan; Newman-Tancredi, Adrian

    2006-09-01

    The dopamine D1/D2 agonist apomorphine (0.63 mg/kg) disrupted prepulse inhibition (PPI) of acoustic startle in rats, a model of sensorimotor gating deficits observed in schizophrenia. All current antipsychotics, which antagonize D2 receptors, prevent this apomorphine-induced deficit. A novel class of antipsychotics possesses, in addition to D2 antagonist property, various levels of 5-HT1A agonist activity. Considering that the latter itself produces PPI deficits, it appeared necessary to assess the potential of this novel class of antipsychotics to reverse apomorphine-PPI deficits. Potent D2 antagonists, like haloperidol (0.63-2.5 mg/kg), risperidone (0.63-10 mg/kg), and olanzapine (0.63-40 mg/kg) prevented apomorphine PPI disruption. The atypical antipsychotics, clozapine (40 mg/kg), nemonapride (0.01-2.5 mg/kg), ziprasidone (10 mg/kg), and aripiprazole (0.01 and 10 mg/kg), which all exhibit 5-HT1A agonist properties, reversed PPI deficits at some doses only, whereas the anti-dyskinetic agent sarizotan (0.16-10 mg/kg), an efficacious 5-HT1A agonist, did not. New generation antipsychotics with marked 5-HT1A agonist properties, such as SLV313 and SSR181507 (0.0025-10 mg/kg and 0.16-10 mg/kg, respectively) did not reverse these deficits whereas bifeprunox (0.04-2.5 mg/kg) did. To reveal the contribution of 5-HT1A agonist properties in the lack of effects of SLV313 and SSR181507, we pretreated rats with the 5-HT1A antagonist WAY100635 (0.63 mg/kg). Under these conditions, significant reversal of PPI deficit was observed, indicating that D2 antagonist properties of SLV313 and SSR181507 are now sufficient to overcome the disruptive effects of apomorphine. To summarize, antipsychotics possessing agonist efficacy at 5-HT1A receptors exhibit diverse profiles against apomorphine-induced PPI deficits, depending on the balance between D2 and 5-HT1A activities, suggesting that they may display distinct activity on some aspects of gating deficits in schizophrenic patients.

  10. The role of adenosine A1 and A2A receptors in the caffeine effect on MDMA-induced DA and 5-HT release in the mouse striatum.

    PubMed

    Górska, A M; Gołembiowska, K

    2015-04-01

    3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") popular as a designer drug is often used with caffeine to gain a stronger stimulant effect. MDMA induces 5-HT and DA release by interaction with monoamine transporters. Co-administration of caffeine and MDMA may aggravate MDMA-induced toxic effects on DA and 5-HT terminals. In the present study, we determined whether caffeine influences DA and 5-HT release induced by MDMA. We also tried to find out if adenosine A1 and A2A receptors play a role in the effect of caffeine by investigating the effect of the selective adenosine A1 and A2A receptor antagonists, DPCPX and KW 6002 on DA and 5-HT release induced by MDMA. Mice were treated with caffeine (10 mg/kg) and MDMA (20 or 40 mg/kg) alone or in combination. DA and 5-HT release in the mouse striatum was measured using in vivo microdialysis. Caffeine exacerbated the effect of MDMA on DA and 5-HT release. DPCPX or KW 6002 co-administered with MDMA had similar influence as caffeine, but KW 6002 was more potent than caffeine or DPCPX. To exclude the contribution of MAO inhibition by caffeine in the caffeine effect on MDMA-induced increase in DA and 5-HT, we also tested the effect of the nonxanthine adenosine receptor antagonist CGS 15943A lacking properties of MAO activity modification. Our findings indicate that adenosine A1 and A2A receptor blockade may account for the caffeine-induced exacerbation of the MDMA effect on DA and 5-HT release and may aggravate MDMA toxicity.

  11. Dynamic Regulation of FoxA1 by Steroid Receptors | Center for Cancer Research

    Cancer.gov

    The estrogen receptor (ER) is a key regulator in breast cancer initiation and progression. A widely discussed model proposes that forkhead box protein A1 (FoxA1) acts as a pioneer factor in cancer by binding and penetrating closed chromatin to allow access by transcription factors (TFs), including ER.

  12. 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

  13. 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

  14. 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…

  15. Potentiation of adenosine A1 receptor agonist CPA-induced antinociception by paeoniflorin in mice.

    PubMed

    Liu, Da-Zhi; Zhao, Fei-Li; Liu, Jing; Ji, Xin-Quan; Ye, Yang; Zhu, Xing-Zu

    2006-08-01

    The effect of paeoniflorin (PF), a major constituent isolated from Paeony radix, on N6-Cyclopentyladenosine (CPA), a selective adenosine A1 receptor (A1 receptor) agonist, induced antinociception was examined in mice. In the tail-pressure test, CPA (0.05, 0.1, 0.2 mg/kg, s.c.) could induce antinociception in a dose-dependent manner. PF (5, 10, 20 mg/kg, s.c.) alone failed to exhibit any antinociceptive effect in mice; however, pretreatment of PF (20 mg/kg, s.c.) could significantly enhance CPA-induced antinociception. Additionally, pretreatment of 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX, 0.25 mg/kg, s.c.), a selective A1 receptor antagonist, could antagonize the antinociceptive effect of combining CPA with PF. Furthermore, in the competitive binding experiments, PF did not displace the binding of [3H]-8-Cyclopentyl-1,3-dipropylxanthine ([3H]-DPCPX) but displaced that of [3H]-2-Chloro-N6-cyclopentyladenosine ([3H]-CCPA, a selective A1 receptor agonist) to the membrane preparation of rat cerebral cortex. These results suggested that PF might selectively increase the binding and antinociceptive effect of CPA by binding with A1 receptor.

  16. Age-dependent changes of presynaptic neuromodulation via A1-adenosine receptors in rat hippocampal slices.

    PubMed

    Sperlágh, B; Zsilla, G; Baranyi, M; Kékes-Szabó, A; Vizi, E S

    1997-10-01

    The presynaptic neuromodulation of stimulation-evoked release of [3H]-acetylcholine by endogenous adenosine, via A1-adenosine receptors, was studied in superfused hippocampal slices taken from 4-, 12- and 24-month-old rats. 8-Cyclopentyl-1,3-dimethylxanthine (0.25 microM), a selective A1-receptor antagonist, increased significantly the electrical field stimulation-induced release of [3H]-acetylcholine in slices prepared from 4- and 12-month-old rats, showing a tonic inhibitory action of endogenous adenosine via stimulation of presynaptic A1-adenosine receptors. In contrast, 8-cyclopentyl-1,3-dimethylxanthine had no effect in 24-month-old rats. 2-Chloroadenosine (10 microM), an adenosine receptor agonist decreased the release of [3H]-acetylcholine in slices taken from 4- and 12-month-old rats, and no significant change was observed in slices taken from 24-month-old rats. In order to show whether the number/or affinity of the A1-receptors was affected in aged rats, [3H]-8-cyclopentyl-1,3-dimethylxanthine binding was studied in hippocampal membranes prepared from rats of different ages. Whereas the Bmax value was significantly lower in 2-year-old rats than in younger counterparts, the dissociation constant (Kd) was not affected by aging, indicating that the density rather than the affinity of adenosine receptors was altered. Endogenous adenosine levels present in the extracellular space were also measured in the superfusate by high performance liquid chromatography (HPLC) coupled with ultraviolet detection, and an age-related increase in the adenosine level was found. In summary, our results indicate that during aging the level of adenosine in the extracellular fluid is increased in the hippocampus. There is a downregulation and reduced responsiveness of presynaptic adenosine A1-receptors, and it seems likely that these changes are due to the enhanced adenosine level in the extracellular space.

  17. Elevated N-terminal pro-brain natriuretic peptide levels predict an enhanced anti-hypertensive and anti-proteinuric benefit of dietary sodium restriction and diuretics, but not angiotensin receptor blockade, in proteinuric renal patients.

    PubMed

    Slagman, Maartje C J; Waanders, Femke; Vogt, Liffert; Damman, Kevin; Hemmelder, Marc; Navis, Gerjan; Laverman, Gozewijn D

    2012-03-01

    Renin-angiotensin aldosterone system (RAAS) blockade only partly reduces blood pressure, proteinuria and renal and cardiovascular risk in chronic kidney disease (CKD) but often requires sodium targeting [i.e. low sodium diet (LS) and/or diuretics] for optimal efficacy. However, both under- and overtitration of sodium targeting can easily occur. We evaluated whether N-terminal pro-brain natriuretic peptide (NT-proBNP), a biomarker of volume expansion, predicts the benefits of sodium targeting in CKD patients. In a cross-over randomized controlled trial, 33 non-diabetic CKD patients (proteinuria 3.8 ± 0.4 g/24 h, blood pressure 143/86 ± 3/2 mmHg, creatinine clearance 89 ± 5 mL/min) were treated during 6-week periods with placebo, angiotensin receptor blockade (ARB; losartan 100 mg/day) and ARB plus diuretics (losartan 100 mg/day plus hydrochlorothiazide 25 mg/day), combined with LS (93 ± 52 mmol Na(+)/24 h) and regular sodium diet (RS; 193 ± 62 mmol Na(+)/24 h, P < 0.001 versus LS), in random order. As controls, 27 healthy volunteers were studied. NT-proBNP was elevated in patients during placebo + RS [90 (60-137) versus 35 (27-45) pg/mL in healthy controls, P = 0.001]. NT-proBNP was lowered by LS, ARB and diuretics and was normalized by ARB + diuretic + LS [39 (26-59) pg/mL, P = 0.65 versus controls]. NT-proBNP levels above the upper limit of normal (>125 pg/mL) predicted a larger reduction of blood pressure and proteinuria by LS and diuretics but not by ARB, during all steps of the titration regimen. Elevated NT-proBNP levels predict an enhanced anti-hypertensive and anti-proteinuric benefit of sodium targeting, but not RAAS blockade, in proteinuric CKD patients. Importantly, this applies to the untreated condition, as well as to the subsequent treatment steps, consisting of RAAS blockade and even RAAS blockade combined with diuretics. NT-proBNP can be a useful tool to identify CKD patients in whom sodium targeting can improve blood pressure and proteinuria.

  18. Central adenosine A1 receptors inhibit cough via suppression of excitatory glutamatergic and tachykininergic neurotransmission.

    PubMed

    El-Hashim, Ahmed Z; Mathews, Seena; Al-Shamlan, Fajer

    2018-05-16

    The A 1 adenosine receptor is reported to mediate several excitatory effects in the airways and has inhibitory effects in the central nervous system. In this study, we investigated the role of peripheral and central A 1 adenosine receptors in regulating cough and airway obstruction. Drugs were administered to guinea pigs via the inhaled or intracerebroventricular (i.c.v.) routes. Cough was induced by exposing guinea pigs to aerosolised 0.4 M citric acid, following drug inhalation or i.c.v. infusion, in a plethysmograph box. An automated analyzer recorded simultaneously both cough and airway obstruction. Inhaled A 1 receptor agonist, cyclopentyladenosine (CPA), dose-dependently inhibited cough (cough: 8 ± 3.4, 6.0 ± 4.5 and 1.9 ± 0.6 vs. 15.4 ± 3.7 for 0.3, 0.6 and 1, mg ml -1 vs. vehicle, respectively) and also inhibited airway obstruction. Similarly, CPA, administered i.c.v., inhibited both the citric acid-induced cough (cough: 21.3 ± 4.0 and 8.8 ± 3.4 vs. 23 ± 3.0 for 1.8 and 3 nmole ml -1 vs. vehicle, respectively) and airway obstruction; this was prevented by pretreatment with the A 1 adenosine receptor antagonist cyclopenty l-1,3-dipropylxanthine (DPCPX; i.c.v.). Treatment with DPCPX alone, dose-dependently enhanced the citric acid-induced cough and airway obstruction. This was reversed following treatment with either the GLUN1 receptor antagonist DL-2-amino-5-phosphonovaleric acid or the NK 1 receptor antagonist FK-888. These findings suggest that activation of either peripheral or central A 1 adenosine receptors inhibits citric acid-induced cough and airway obstruction. The data also suggest that tonic activation of central adenosine A 1 receptors serves as a negative regulator of cough and airway obstruction, secondary to inhibition of excitatory glutamatergic and tachykininergic neurotransmission. This article is protected by copyright. All rights reserved.

  19. Regulation of renal adenosine A(1) receptors: effect of dietary sodium chloride.

    PubMed

    Smith, J A; Whitaker, E M; Yaktubay, N; Morton, M J; Bowmer, C J; Yates, M S

    1999-11-12

    The influence of dietary NaCl on the regulation of renal adenosine A(1) receptors was investigated in the rat. Renal membranes from rats fed on a diet low (0.04%) in NaCl showed a 46% increase in B(max) for the binding of [3H]-1,3-dipropyl-8-cyclopentylxanthine ([3H]DPCPX), a selective adenosine A(1) receptor antagonist, compared to membranes from rats fed on a normal diet (0.4% NaCl). Conversely, a high NaCl diet (4.0%) resulted in a 37% decrease in B(max). Levels of renal adenosine A(1) receptor mRNA were 65% lower in rats on a high salt diet. Autoradiographic studies showed that, for the inner medullary collecting ducts, a low NaCl diet resulted in a 30% increase in [3H]DPCPX binding with a 39% decrease noted in rats maintained on a high salt diet. The results indicate that changes in adenosine A(1) receptor density may represent a novel mechanism whereby the kidneys adapt to changes in salt load.

  20. α-Adrenoceptor blockade modifies neurally induced atrial arrhythmias

    PubMed Central

    Richer, Louis-Philippe; Vinet, Alain; Kus, Teresa; Cardinal, René; Ardell, Jeffrey L.; Armour, John Andrew

    2008-01-01

    Our objective was to determine whether neuronally induced atrial arrhythmias can be modified by α-adrenergic receptor blockade. In 30 anesthetized dogs, trains of five electrical stimuli (1 mA; 1 ms) were delivered immediately after the P wave of the ECG to mediastinal nerves associated with the superior vena cava. Regional atrial electrical events were monitored with 191 atrial unipolar electrodes. Mediastinal nerve sites were identified that reproducibly initiated atrial arrhythmias. These sites were then restimulated following 1 h (time control, n = 6), or the intravenous administration of naftopidil (α1-adrenergic blocker: 0.2 mg/kg, n = 6), yohimbine (α2-adrenergic blocker: 1 mg/kg, n = 6) or both (n = 8). A ganglionic blocker (hexamethonium: 1 mg/kg) was tested in four dogs. Stimulation of mediastinal nerves sites consistently elicited atrial tachyarrhythmias. Repeat stimulation after 1 h in the time-control group exerted a 19% decrease of the sites still able to induce atrial tachyarrhythmias. Hexamethonium inactivated 78% of the previously active sites. Combined α-adrenoceptor blockade inactivated 72% of the previously active sites. Bradycardia responses induced by mediastinal nerve stimulation were blunted by hexamethonium, but not by α1,2-adrenergic blockade. Naftopidil or yohimbine alone eliminated atrial arrhythmia induction from 31% and 34% of the sites (similar to time control). We conclude that heterogeneous activation of the intrinsic cardiac nervous system results in atrial arrhythmias that involve intrinsic cardiac neuronal α-adrenoceptors. In contrast to the global suppression exerted by hexamethonium, we conclude that α-adrenoceptor blockade targets intrinsic cardiac local circuit neurons involved in arrhythmia formation and not the flow-through efferent projections of the cardiac nervous system. PMID:18716036

  1. Alpha-adrenoceptor blockade modifies neurally induced atrial arrhythmias.

    PubMed

    Richer, Louis-Philippe; Vinet, Alain; Kus, Teresa; Cardinal, René; Ardell, Jeffrey L; Armour, John Andrew

    2008-10-01

    Our objective was to determine whether neuronally induced atrial arrhythmias can be modified by alpha-adrenergic receptor blockade. In 30 anesthetized dogs, trains of five electrical stimuli (1 mA; 1 ms) were delivered immediately after the P wave of the ECG to mediastinal nerves associated with the superior vena cava. Regional atrial electrical events were monitored with 191 atrial unipolar electrodes. Mediastinal nerve sites were identified that reproducibly initiated atrial arrhythmias. These sites were then restimulated following 1 h (time control, n = 6), or the intravenous administration of naftopidil (alpha(1)-adrenergic blocker: 0.2 mg/kg, n = 6), yohimbine (alpha(2)-adrenergic blocker: 1 mg/kg, n = 6) or both (n = 8). A ganglionic blocker (hexamethonium: 1 mg/kg) was tested in four dogs. Stimulation of mediastinal nerves sites consistently elicited atrial tachyarrhythmias. Repeat stimulation after 1 h in the time-control group exerted a 19% decrease of the sites still able to induce atrial tachyarrhythmias. Hexamethonium inactivated 78% of the previously active sites. Combined alpha-adrenoceptor blockade inactivated 72% of the previously active sites. Bradycardia responses induced by mediastinal nerve stimulation were blunted by hexamethonium, but not by alpha(1,2)-adrenergic blockade. Naftopidil or yohimbine alone eliminated atrial arrhythmia induction from 31% and 34% of the sites (similar to time control). We conclude that heterogeneous activation of the intrinsic cardiac nervous system results in atrial arrhythmias that involve intrinsic cardiac neuronal alpha-adrenoceptors. In contrast to the global suppression exerted by hexamethonium, we conclude that alpha-adrenoceptor blockade targets intrinsic cardiac local circuit neurons involved in arrhythmia formation and not the flow-through efferent projections of the cardiac nervous system.

  2. Adenosine transiently modulates stimulated dopamine release in the caudate putamen via A1 receptors

    PubMed Central

    Ross, Ashley E.; Venton, B. Jill

    2014-01-01

    Adenosine modulates dopamine in the brain via A1 and A2A receptors, but that modulation has only been characterized on a slow time scale. Recent studies have characterized a rapid signaling mode of adenosine that suggests a possible rapid modulatory role. Here, fast-scan cyclic voltammetry was used to characterize the extent to which transient adenosine changes modulate stimulated dopamine release (5 pulses at 60 Hz) in rat caudate putamen brain slices. Exogenous adenosine was applied and dopamine concentration monitored. Adenosine only modulated dopamine when it was applied 2 or 5 s before stimulation. Longer time intervals and bath application of 5 µM adenosine did not decrease dopamine release. Mechanical stimulation of endogenous adenosine 2s before dopamine stimulation also decreased stimulated dopamine release by 41 ± 7 %, similar to the 54 ± 6 % decrease in dopamine after exogenous adenosine application. Dopamine inhibition by transient adenosine was recovered within 10 minutes. The A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) blocked the dopamine modulation, whereas dopamine modulation was unaffected by the A2A receptor antagonist SCH 442416. Thus, transient adenosine changes can transiently modulate phasic dopamine release via A1 receptors. These data demonstrate that adenosine has a rapid, but transient, modulatory role in the brain. PMID:25219576

  3. 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.

  4. 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.

  5. Adenosine-A1 Receptor Agonist Induced Hyperalgesic Priming Type II

    PubMed Central

    Araldi, Dioneia; Ferrari, Luiz F.; Levine, Jon D.

    2016-01-01

    We have recently shown that repeated exposure of the peripheral terminal of the primary afferent nociceptor to the mu-opioid receptor (MOR) agonist DAMGO ([D-Ala2, N-Me-Phe4, Gly5-ol]-Enkephalin acetate salt) induces a model of the transition to chronic pain that we have termed Type II hyperalgesic priming. Similar to Type I hyperalgesic priming, there is a markedly prolonged response to subsequent administration of proalgesic cytokines, prototypically prostaglandin E2 (PGE2). However, Type II hyperalgesic priming differs from Type I in being rapidly induced, protein kinase A (PKA), rather than PKCε dependent, not reversed by a protein translation inhibitor, occurring in female as well as in male rats, and isolectin B4-negative neuron dependent. We report that as with the repeated injection of a MOR agonist, the repeated administration of an agonist at the A1-adenosine receptor, also a Gi-protein coupled receptor, N6-Cyclopentyladenosine (CPA), also produces priming similar to DAMGO-induced Type II hyperalgesic priming. In this study we demonstrate that priming induced by repeated exposure to this A1-adenosine receptor agonist shares the same mechanisms as MOR-agonist induced priming. However, the prolongation of PGE2 hyperalgesia induced by repeated administration of CPA depends on G-protein αi subunit activation, differently from DAMGO-induced Type II priming, in which it depends on the β/γ subunit. These data implicate a novel form of Gi-protein signaling pathway in the Type II hyperalgesic priming induced by repeated administration of an agonist at A1-adenosine receptor to the peripheral terminal of the nociceptor. PMID:26588695

  6. Adenosine A1-Dopamine D1 Receptor Heteromers Control the Excitability of the Spinal Motoneuron.

    PubMed

    Rivera-Oliver, Marla; Moreno, Estefanía; Álvarez-Bagnarol, Yocasta; Ayala-Santiago, Christian; Cruz-Reyes, Nicole; Molina-Castro, Gian Carlo; Clemens, Stefan; Canela, Enric I; Ferré, Sergi; Casadó, Vicent; Díaz-Ríos, Manuel

    2018-05-24

    While the role of the ascending dopaminergic system in brain function and dysfunction has been a subject of extensive research, the role of the descending dopaminergic system in spinal cord function and dysfunction is just beginning to be understood. Adenosine plays a key role in the inhibitory control of the ascending dopaminergic system, largely dependent on functional complexes of specific subtypes of adenosine and dopamine receptors. Combining a selective destabilizing peptide strategy with a proximity ligation assay and patch-clamp electrophysiology in slices from male mouse lumbar spinal cord, the present study demonstrates the existence of adenosine A 1 -dopamine D 1 receptor heteromers in the spinal motoneuron by which adenosine tonically inhibits D 1 receptor-mediated signaling. A 1 -D 1 receptor heteromers play a significant control of the motoneuron excitability, represent main targets for the excitatory effects of caffeine in the spinal cord and can constitute new targets for the pharmacological therapy after spinal cord injury, motor aging-associated disorders and restless legs syndrome.

  7. Interaction of valerian extracts of different polarity with adenosine receptors: identification of isovaltrate as an inverse agonist at A1 receptors.

    PubMed

    Lacher, Svenja K; Mayer, Ralf; Sichardt, Kathrin; Nieber, Karen; Müller, Christa E

    2007-01-15

    A series of extracts of valerian roots (Valeriana officinalis L.) was prepared with solvents of different polarity. Polar as well as nonpolar extracts were found to interact with adenosine A(1) receptors. While polar extracts activated A(1) receptors (partial agonistic activity), nonpolar extracts showed antagonistic or inverse agonistic activity at A(1) receptors, as demonstrated by GTPgammaS binding assays at human recombinant A(1) receptors stably expressed in Chinese hamster ovary (CHO) cells. Guided by radioligand binding assays, fractionation of a lipophilic petroleum ether:diethyl ether (1:1) extract led to the isolation of isovaltrate, which was characterized as a potent, highly efficacious inverse agonist at adenosine A(1) receptors (K(i) rat A(1): 2.05 microM). In experiments at rat brain slices measuring post-synaptic potentials (PSPs) in cortical neurons, isovaltrate at least partly reversed the reduction in the PSPs induced by the adenosine A(1) receptor agonist N(6)-cyclopentyladenosine (CPA). Isovaltrate may serve as a new lead structure for the development of inverse agonists at adenosine A(1) receptors. The common use of hydrophilic, but not lipophilic valerian extracts as mild sleep-inducing agents is consistent with the opposite actions of hydrophilic and lipophilic extracts on adenosine receptors.

  8. Adenosine A1 receptors contribute to immune regulation after neonatal hypoxic ischemic brain injury.

    PubMed

    Winerdal, Max; Winerdal, Malin E; Wang, Ying-Qing; Fredholm, Bertil B; Winqvist, Ola; Ådén, Ulrika

    2016-03-01

    Neonatal brain hypoxic ischemia (HI) often results in long-term motor and cognitive impairments. Post-ischemic inflammation greatly effects outcome and adenosine receptor signaling modulates both HI and immune cell function. Here, we investigated the influence of adenosine A1 receptor deficiency (A1R(-/-)) on key immune cell populations in a neonatal brain HI model. Ten-day-old mice were subjected to HI. Functional outcome was assessed by open locomotion and beam walking test and infarction size evaluated. Flow cytometry was performed on brain-infiltrating cells, and semi-automated analysis of flow cytometric data was applied. A1R(-/-) mice displayed larger infarctions (+33%, p < 0.05) and performed worse in beam walking tests (44% more mistakes, p < 0.05) than wild-type (WT) mice. Myeloid cell activation after injury was enhanced in A1R(-/-) versus WT brains. Activated B lymphocytes expressing IL-10 infiltrated the brain after HI in WT, but were less activated and did not increase in relative frequency in A1R(-/-). Also, A1R(-/-) B lymphocytes expressed less IL-10 than their WT counterparts, the A1R antagonist DPCPX decreased IL-10 expression whereas the A1R agonist CPA increased it. CD4(+) T lymphocytes including FoxP3(+) T regulatory cells, were unaffected by genotype, whereas CD8(+) T lymphocyte responses were smaller in A1R(-/-) mice. Using PCA to characterize the immune profile, we could discriminate the A1R(-/-) and WT genotypes as well as sham operated from HI-subjected animals. We conclude that A1R signaling modulates IL-10 expression by immune cells, influences the activation of these cells in vivo, and affects outcome after HI.

  9. Characterization of the swine adipocyte A1 adenosine receptor using an optimized assay system.

    PubMed

    Dong, Q; Schuchman, J; Carey, G B

    1994-07-01

    The radioligand binding assay of A1 adenosine receptors in adipocyte crude plasma membrane from Yucatan miniature swine was optimized by evaluating 17 factors involved in the assay. Significant effects of CHAPS, adenosine deaminase, EDTA, pre-rinsing glass fiber filters and pH were found for the binding measurements. Using the optimized procedure, [3H]8-cyclopentyl-1,3-dipropylxanthine, ([3H]-DPCPX) binding to A1 adenosine receptors in swine subcutaneous adipocyte crude plasma membrane was measured; Bmax and Kd values were 479 +/- 77 fmol/mg protein and 0.87 +/- 0.10 nM, respectively. Values for mesenteric adipose tissue from sedentary swine and subcutaneous adipose tissue from exercise-trained swine were also measured.

  10. Tandospirone, a 5-HT1A partial agonist, ameliorates aberrant lactate production in the prefrontal cortex of rats exposed to blockade of N-methy-D-aspartate receptors; Toward the therapeutics of cognitive impairment of schizophrenia.

    PubMed

    Uehara, Takashi; Matsuoka, Tadasu; Sumiyoshi, Tomiki

    2014-01-01

    Augmentation therapy with serotonin-1A (5-HT1A) receptor partial agonists has been suggested to improve cognitive impairment in patients with schizophrenia. Decreased activity of prefrontal cortex may provide a basis for cognitive deficits of the disease. Lactate plays a significant role in the supply of energy to the brain, and glutamatergic neurotransmission contributes to lactate production. The purposes of this study were to examine the effect of repeated administration (once a daily for 4 days) of tandospirone (0.05 or 5 mg/kg) on brain energy metabolism, as represented by extracellular lactate concentration (eLAC) in the medial prefrontal cortex (mPFC) of a rat model of schizophrenia. Four-day treatment with MK-801, an NMDA-R antagonist, prolonged eLAC elevation induced by foot-shock stress (FS). Co-administration with the high-dose tandospirone suppressed prolonged FS-induced eLAC elevation in rats receiving MK-801, whereas tandospirone by itself did not affected eLAC increment. These results suggest that stimulation of 5-HT1A receptors ameliorates abnormalities of energy metabolism in the mPFC due to blockade of NMDA receptors. These findings provide a possible mechanism, based on brain energy metabolism, by which 5-HT1A agonism improve cognitive impairment of schizophrenia and related disorders.

  11. Recovery sleep after extended wakefulness restores elevated A1 adenosine receptor availability in the human brain

    PubMed Central

    Elmenhorst, Eva-Maria; Hennecke, Eva; Kroll, Tina; Matusch, Andreas; Aeschbach, Daniel; Bauer, Andreas

    2017-01-01

    Adenosine and functional A1 adenosine receptor (A1AR) availability are supposed to mediate sleep–wake regulation and cognitive performance. We hypothesized that cerebral A1AR availability after an extended wake period decreases to a well-rested state after recovery sleep. [18F]CPFPX positron emission tomography was used to quantify A1AR availability in 15 healthy male adults after 52 h of sleep deprivation and following 14 h of recovery sleep. Data were additionally compared with A1AR values after 8 h of baseline sleep from an earlier dataset. Polysomnography, cognitive performance, and sleepiness were monitored. Recovery from sleep deprivation was associated with a decrease in A1AR availability in several brain regions, ranging from 11% (insula) to 14% (striatum). A1AR availabilities after recovery did not differ from baseline sleep in the control group. The degree of performance impairment, sleepiness, and homeostatic sleep-pressure response to sleep deprivation correlated negatively with the decrease in A1AR availability. Sleep deprivation resulted in a higher A1AR availability in the human brain. The increase that was observed after 52 h of wakefulness was restored to control levels during a 14-h recovery sleep episode. Individuals with a large increase in A1AR availability were more resilient to sleep-loss effects than those with a subtle increase. This pattern implies that differences in endogenous adenosine and A1AR availability might be causal for individual responses to sleep loss. PMID:28373571

  12. Effects of serotonin 2A/1A receptor stimulation on social exclusion processing

    PubMed Central

    Preller, Katrin H.; Pokorny, Thomas; Hock, Andreas; Kraehenmann, Rainer; Stämpfli, Philipp; Seifritz, Erich; Scheidegger, Milan; Vollenweider, Franz X.

    2016-01-01

    Social ties are crucial for physical and mental health. However, psychiatric patients frequently encounter social rejection. Moreover, an increased reactivity to social exclusion influences the development, progression, and treatment of various psychiatric disorders. Nevertheless, the neuromodulatory substrates of rejection experiences are largely unknown. The preferential serotonin (5-HT) 2A/1A receptor agonist, psilocybin (Psi), reduces the processing of negative stimuli, but whether 5-HT2A/1A receptor stimulation modulates the processing of negative social interactions remains unclear. Therefore, this double-blind, randomized, counterbalanced, cross-over study assessed the neural response to social exclusion after the acute administration of Psi (0.215 mg/kg) or placebo (Pla) in 21 healthy volunteers by using functional magnetic resonance imaging (fMRI) and resting-state magnetic resonance spectroscopy (MRS). Participants reported a reduced feeling of social exclusion after Psi vs. Pla administration, and the neural response to social exclusion was decreased in the dorsal anterior cingulate cortex (dACC) and the middle frontal gyrus, key regions for social pain processing. The reduced neural response in the dACC was significantly correlated with Psi-induced changes in self-processing and decreased aspartate (Asp) content. In conclusion, 5-HT2A/1A receptor stimulation with psilocybin seems to reduce social pain processing in association with changes in self-experience. These findings may be relevant to the normalization of negative social interaction processing in psychiatric disorders characterized by increased rejection sensitivity. The current results also emphasize the importance of 5-HT2A/1A receptor subtypes and the Asp system in the control of social functioning, and as prospective targets in the treatment of sociocognitive impairments in psychiatric illnesses. PMID:27091970

  13. The effect of neonatal N-methyl-D-aspartate receptor blockade on exploratory and anxiety-like behaviors in adult BALB/c and C57BL/6 mice.

    PubMed

    Akillioglu, Kubra; Binokay, Secil; Kocahan, Sayad

    2012-07-15

    N-methyl-D-aspartate (NMDA) receptors play an important role in brain maturation and developmental processes. In our study, we evaluated the effects of neonatal NMDA receptor blockade on exploratory locomotion and anxiety-like behaviors of adult BALB/c and C57BL/6 mice. In this study, NMDA receptor hypofunction was induced 7-10 days after birth using MK-801 in BALB/c and C57BL/6 mice (0.25mg/kg twice a day for 4 days via intraperitoneal injection). The open-field (OF) and elevated plus maze (EPM) tests were used to evaluate exploratory locomotion and anxiety-like behaviors. In the OF, BALB/c mice spent less time in the center of the field (p<0.05) and had less vertical locomotor activity (p<0.01) compared to C57BL/6 mice. In BALB/c mice, MK-801 caused a decrease in vertical and horizontal locomotor activity in the OF test, compared to the control group (p<0.05). In C57BL/6 mice, MK-801 treatment increased horizontal locomotor activity and decreased time spent in the center in the OF test (p<0.05). In the EPM, the number of open-arm entries, the percentage of open-arm time (p<0.01) and total arm entries (p<0.05) were lower in BALB/c mice compared to C57BL/6 mice. In BALB/c mice, MK-801 caused an increase in the percentage of open-arm time compared to the control group (p<0.05). In C57BL/6 mice, MK-801 caused a decrease in the percentage of open-arm time compared to the control group (p<0.05). MK-801 decreased exploratory and anxiety-like behaviors in BALB/c mice. In contrast, MK-801 increased exploratory and anxiety-like behaviors in C57BL/6 mice. In conclusion, hereditary factors may play an important role in neonatal NMDA receptor blockade-induced responses. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Overexpression of androgen receptor and forkhead-box A1 protein in apocrine breast carcinoma.

    PubMed

    Sasahara, Manami; Matsui, Akira; Ichimura, Yoshiko; Hirakata, Yuuko; Murata, Yuuya; Marui, Eiji

    2014-03-01

    Apocrine breast carcinoma often lacks estrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor type-2 (HER2) expression. Accordingly, development of a new treatment strategy is important for this type of cancer. The growth stimulus through the androgen receptor (AR) can be a candidate for targeted treatment. Therefore, we examined the factors related to AR transcription. We immunohistochemically evaluated 54 apocrine cancer lesions for ER, PgR, AR, HER2, Ki-67, forkhead-box protein A1 (FOXA1), and prostate-specific antigen (PSA) expression. ER, PgR, and HER2 were expressed at a low level, thus 44 out of 54 (81.4%) cases were of triple-negative breast cancer. AR, PSA and FOXA1 were expressed in 100% (54/54), 48% (26/54) and 93% (50/54) of cases, respectively. Most of apocrine breast carcinomas were immunohistochemically-positive for AR and FOXA1. Anti-androgenic therapies can potentially serve as a cancer-targeting therapy for apocrine breast carcinoma.

  15. Systemic blockade of dopamine D2-like receptors increases high-voltage spindles in the globus pallidus and motor cortex of freely moving rats.

    PubMed

    Yang, Chen; Ge, Shun-Nan; Zhang, Jia-Rui; Chen, Lei; Yan, Zhi-Qiang; Heng, Li-Jun; Zhao, Tian-Zhi; Li, Wei-Xin; Jia, Dong; Zhu, Jun-Ling; Gao, Guo-Dong

    2013-01-01

    High-voltage spindles (HVSs) have been reported to appear spontaneously and widely in the cortical-basal ganglia networks of rats. Our previous study showed that dopamine depletion can significantly increase the power and coherence of HVSs in the globus pallidus (GP) and motor cortex of freely moving rats. However, it is unclear whether dopamine regulates HVS activity by acting on dopamine D₁-like receptors or D₂-like receptors. We employed local-field potential and electrocorticogram methods to simultaneously record the oscillatory activities in the GP and primary motor cortex (M1) in freely moving rats following systemic administration of dopamine receptor antagonists or saline. The results showed that the dopamine D₂-like receptor antagonists, raclopride and haloperidol, significantly increased the number and duration of HVSs, and the relative power associated with HVS activity in the GP and M1 cortex. Coherence values for HVS activity between the GP and M1 cortex area were also significantly increased by dopamine D₂-like receptor antagonists. On the contrary, the selective dopamine D₁-like receptor antagonist, SCH23390, had no significant effect on the number, duration, or relative power of HVSs, or HVS-related coherence between M1 and GP. In conclusion, dopamine D₂-like receptors, but not D₁-like receptors, were involved in HVS regulation. This supports the important role of dopamine D₂-like receptors in the regulation of HVSs. An siRNA knock-down experiment on the striatum confirmed our conclusion.

  16. Basal Levels of AMPA Receptor GluA1 Subunit Phosphorylation at Threonine 840 and Serine 845 in Hippocampal Neurons

    ERIC Educational Resources Information Center

    Babiec, Walter E.; Guglietta, Ryan; O'Dell, Thomas J.

    2016-01-01

    Dephosphorylation of AMPA receptor (AMPAR) GluA1 subunits at two sites, serine 845 (S845) and threonine 840 (T840), is thought to be involved in NMDA receptor-dependent forms of long-term depression (LTD). Importantly, the notion that dephosphorylation of these sites contributes to LTD assumes that a significant fraction of GluA1 subunits are…

  17. Adenosine A1 receptor: A neuroprotective target in light induced retinal degeneration.

    PubMed

    Soliño, Manuel; López, Ester María; Rey-Funes, Manuel; Loidl, César Fabián; Larrayoz, Ignacio M; Martínez, Alfredo; Girardi, Elena; López-Costa, Juan José

    2018-01-01

    Light induced retinal degeneration (LIRD) is a useful model that resembles human retinal degenerative diseases. The modulation of adenosine A1 receptor is neuroprotective in different models of retinal injury. The aim of this work was to evaluate the potential neuroprotective effect of the modulation of A1 receptor in LIRD. The eyes of rats intravitreally injected with N6-cyclopentyladenosine (CPA), an A1 agonist, which were later subjected to continuous illumination (CI) for 24 h, showed retinas with a lower number of apoptotic nuclei and a decrease of Glial Fibrillary Acidic Protein (GFAP) immunoreactive area than controls. Lower levels of activated Caspase 3 and GFAP were demonstrated by Western Blot (WB) in treated animals. Also a decrease of iNOS, TNFα and GFAP mRNA was demonstrated by RT-PCR. A decrease of Iba 1+/MHC-II+ reactive microglial cells was shown by immunohistochemistry. Electroretinograms (ERG) showed higher amplitudes of a-wave, b-wave and oscillatory potentials after CI compared to controls. Conversely, the eyes of rats intravitreally injected with dipropylcyclopentylxanthine (DPCPX), an A1 antagonist, and subjected to CI for 24 h, showed retinas with a higher number of apoptotic nuclei and an increase of GFAP immunoreactive area compared to controls. Also, higher levels of activated Caspase 3 and GFAP were demonstrated by Western Blot. The mRNA levels of iNOS, nNOS and inflammatory cytokines (IL-1β and TNFα) were not modified by DPCPX treatment. An increase of Iba 1+/MHC-II+ reactive microglial cells was shown by immunohistochemistry. ERG showed that the amplitudes of a-wave, b-wave, and oscillatory potentials after CI were similar to control values. A single pharmacological intervention prior illumination stress was able to swing retinal fate in opposite directions: CPA was neuroprotective, while DPCPX worsened retinal damage. In summary, A1 receptor agonism is a plausible neuroprotective strategy in LIRD.

  18. Coulomb Blockade Plasmonic Switch.

    PubMed

    Xiang, Dao; Wu, Jian; Gordon, Reuven

    2017-04-12

    Tunnel resistance can be modulated with bias via the Coulomb blockade effect, which gives a highly nonlinear response current. Here we investigate the optical response of a metal-insulator-nanoparticle-insulator-metal structure and show switching of a plasmonic gap from insulator to conductor via Coulomb blockade. By introducing a sufficiently large charging energy in the tunnelling gap, the Coulomb blockade allows for a conductor (tunneling) to insulator (capacitor) transition. The tunnelling electrons can be delocalized over the nanocapacitor again when a high energy penalty is added with bias. We demonstrate that this has a huge impact on the plasmonic resonance of a 0.51 nm tunneling gap with ∼70% change in normalized optical loss. Because this structure has a tiny capacitance, there is potential to harness the effect for high-speed switching.

  19. 1-Aryl-1H- and 2-aryl-2H-1,2,3-triazole derivatives blockade P2X7 receptor in vitro and inflammatory response in vivo.

    PubMed

    Gonzaga, Daniel Tadeu Gomes; Ferreira, Leonardo Braga Gomes; Moreira Maramaldo Costa, Thadeu Estevam; von Ranke, Natalia Lidmar; Anastácio Furtado Pacheco, Paulo; Sposito Simões, Ana Paula; Arruda, Juliana Carvalho; Dantas, Luiza Pereira; de Freitas, Hércules Rezende; de Melo Reis, Ricardo Augusto; Penido, Carmen; Bello, Murilo Lamim; Castro, Helena Carla; Rodrigues, Carlos Rangel; Ferreira, Vitor Francisco; Faria, Robson Xavier; da Silva, Fernando de Carvalho

    2017-10-20

    Fifty-one 1,2,3-triazole derivatives were synthesized and evaluated with respect to P2X7 receptor (P2X7R) activity and its associated pore. These triazoles were screened in vitro for dye uptake assay and its cytotoxicity against mammalian cell types. Seven 1,2,3-triazole derivatives (5e, 6e, 8h, 9d, 9i, 11, and 12) potently blocked P2X7 receptor pore formation in vitro (J774.G8 cells and peritoneal macrophages). All blockers displayed IC 50 value inferior to 500 nM, and they have low toxicity in either cell types. These seven selected triazoles inhibited P2X7R mediated interleukin-1 (IL-1β) release. In particular, compound 9d was the most potent P2X7R blocker. Additionally, in mouse acute models of inflammatory responses induced by ATP or carrageenan administration in the paw, compound 9d promoted a potent blocking response. Similarly, 9d also reduced mouse LPS-induced pleurisy cellularity. In silico predictions indicate this molecule appropriate to develop an anti-inflammatory agent when it was compared to commercial analogs. Electrophysiological studies suggest a competitive mechanism of action of 9d to block P2X7 receptor. Molecular docking was performed on the ATP binding site in order to observe the preferential interaction pose, indicating that binding mode of the 9d is by interacting its 1,2,3-triazole and ether moiety with positively charged residues and with its chlorobenzene moiety orientated toward the apolar end of the ATP binding site which are mainly composed by the Ile170, Trp167 and Leu309 residues from α subunit. These results highlight 9d derivative as a drug candidate with potential therapeutic application based on P2X7 receptor blockade. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  20. Enhancement of cortical extracellular 5-HT by 5-HT1A and 5-HT2C receptor blockade restores the antidepressant-like effect of citalopram in non-responder mice.

    PubMed

    Calcagno, Eleonora; Guzzetti, Sara; Canetta, Alessandro; Fracasso, Claudia; Caccia, Silvio; Cervo, Luigi; Invernizzi, Roberto W

    2009-07-01

    We recently found that the response of DBA/2 mice to SSRIs in the forced swim test (FST) was impaired and they also had a smaller basal and citalopram-stimulated increase in brain extracellular serotonin (5-HT) than 'responder' strains. We employed intracerebral microdialysis, FST and selective antagonists of 5-HT1A and 5-HT2C receptors to investigate whether enhancing the increase in extracellular 5-HT reinstated the anti-immobility effect of citalopram in the FST. WAY 100635 (0.3 mg/kg s.c.) or SB 242084 (1 mg/kg s.c.), respectively a selective 5-HT1A and 5-HT2C receptor antagonist, raised the effect of citalopram (5 mg/kg) on extracellular 5-HT in the medial prefrontal cortex of DBA/2N mice (citalopram alone 5.2+/-0.3 fmol/20 microl, WAY 100635+citalopram 9.9+/-2.1 fmol/20 microl, SB 242084+ citalopram 7.6+/-1.0 fmol/20 microl) to the level reached in 'responder' mice given citalopram alone. The 5-HT receptor antagonists had no effect on the citalopram-induced increase in extracellular 5-HT in the dorsal hippocampus. The combination of citalopram with WAY 100635 or SB 242084 significantly reduced immobility time in DBA/2N mice that otherwise did not respond to either drug singly. Brain levels of citalopram in mice given citalopram alone or with 5-HT antagonists did not significantly differ. The results confirm that impaired 5-HT transmission accounts for the lack of effect of citalopram in the FST and suggest that enhancing the effect of SSRIs on extracellular 5-HT, through selective blockade of 5-HT1A and 5-HT2C receptors, could be a useful strategy to restore the response in treatment-resistant depression.

  1. Small-animal PET study of adenosine A(1) receptors in rat brain: blocking receptors and raising extracellular adenosine.

    PubMed

    Paul, Soumen; Khanapur, Shivashankar; Rybczynska, Anna A; Kwizera, Chantal; Sijbesma, Jurgen W A; Ishiwata, Kiichi; Willemsen, Antoon T M; Elsinga, Philip H; Dierckx, Rudi A J O; van Waarde, Aren

    2011-08-01

    Activation of adenosine A(1) receptors (A(1)R) in the brain causes sedation, reduces anxiety, inhibits seizures, and promotes neuroprotection. Cerebral A(1)R can be visualized using 8-dicyclopropylmethyl-1-(11)C-methyl-3-propyl-xanthine ((11)C-MPDX) and PET. This study aims to test whether (11)C-MPDX can be used for quantitative studies of cerebral A(1)R in rodents. (11)C-MPDX was injected (intravenously) into isoflurane-anesthetized male Wistar rats (300 g). A dynamic scan of the central nervous system was obtained, using a small-animal PET camera. A cannula in a femoral artery was used for blood sampling. Three groups of animals were studied: group 1, controls (saline-treated); group 2, animals pretreated with the A(1)R antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 1 mg, intraperitoneally); and group 3, animals pretreated (intraperitoneally) with a 20% solution of ethanol in saline (2 mL) plus the adenosine kinase inhibitor 4-amino-5-(3-bromophenyl)-7-(6-morpholino-pyridin-3-yl)pyrido[2,3-d] pyrimidine dihydrochloride (ABT-702) (1 mg). DPCPX is known to occupy cerebral A(1)R, whereas ethanol and ABT-702 increase extracellular adenosine. In groups 1 and 3, the brain was clearly visualized. High uptake of (11)C-MPDX was noted in striatum, hippocampus, and cerebellum. In group 2, tracer uptake was strongly suppressed and regional differences were abolished. The treatment of group 3 resulted in an unexpected 40%-45% increase of the cerebral uptake of radioactivity as indicated by increases of PET standardized uptake value, distribution volume from Logan plot, nondisplaceable binding potential from 2-tissue-compartment model fit, and standardized uptake value from a biodistribution study performed after the PET scan. The partition coefficient of the tracer (K(1)/k(2) from the model fit) was not altered under the study conditions. (11)C-MPDX shows a regional distribution in rat brain consistent with binding to A(1)R. Tracer binding is blocked by the selective A

  2. Antenatal blockade of N-methyl-D-aspartate receptors by Memantine reduces the susceptibility to diabetes induced by a high-fat diet in rats with intrauterine growth restriction.

    PubMed

    Huang, Xiao-Ting; Yue, Shao-Jie; Li, Chen; Guo, Jia; Huang, Yan-Hong; Han, Jian-Zhong; Feng, Dan-Dan; Luo, Zi-Qiang

    2017-05-01

    Intrauterine growth retardation (IUGR) is closely related to the later development of type 2 diabetes in adulthood. Excessive activation of N-methly-D-aspartate receptors (NMDARs) causes excitatory neurotoxicity, resulting in neuronal injury or death. Inhibition of NMDARs enhances the glucose-stimulated insulin secretion and survival of islet cells in type 2 diabetic mouse and human islets. Here, we examined whether antenatal blockade of NMDARs by Memantine could decrease the risk of diabetes induced by a high-fat (HF) diet at adulthood in IUGR rats. Pregnant SD rats were assigned to four groups: control, IUGR, Memantine, and Memantine + IUGR. The pregnant rats were exposed to hypoxic conditions (FiO2 = 0.105) for 8 h/day (IUGR group) or given a daily Memantine injection (5 mg/kg, i.p.) before hypoxia exposure from embryonic day (E) 14.5 to E 20.5 (Memantine + IUGR). The offspring were fed an HF diet with 60% of the calories from age 4 to 12 weeks. We found that NMDAR mRNAs were expressed in the fetal rat pancreas. An HF diet resulted in a high rate of diabetes at adulthood in the IUGR group. Antenatal Memantine treatment decreased the risk of diabetes at adulthood of rats with IUGR, which was associated with rescued glucose tolerance, increased insulin release, improved the insulin sensitivity, and increased expression of genes related to beta-cell function in the pancreas. Together, our results suggest that antenatal blockade of NMDARs by Memantine in pregnant rats improves fetal development and reduces the susceptibility to diabetes at adulthood in offspring. © The Authors 2017. Published by Oxford University Press on behalf of Society for the Study of Reproduction. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Activation of adenosine A(1) receptors alters behavioral and biochemical parameters in hyperthyroid rats.

    PubMed

    Bruno, Alessandra Nejar; Fontella, Fernanda Urruth; Bonan, Carla Denise; Barreto-Chaves, Maria Luiza M; Dalmaz, Carla; Sarkis, João José Freitas

    2006-02-28

    Adenosine acting on A(1) receptors has been related with neuroprotective and neuromodulatory actions, protection against oxidative stress and decrease of anxiety and nociceptive signaling. Previous studies demonstrated an inhibition of the enzymes that hydrolyze ATP to adenosine in the rat central nervous system after hyperthyroidism induction. Manifestations of hyperthyroidism include increased anxiety, nervousness, high O(2) consumption and physical hyperactivity. Here, we investigated the effects of administration of a specific agonist of adenosine A(1) receptor (N(6)-cyclopentyladenosine; CPA) on nociception, anxiety, exploratory response, locomotion and brain oxidative stress of hyperthyroid rats. Hyperthyroidism was induced by daily intraperitoneal injections of l-thyroxine (T4) for 14 days. Nociception was assessed with a tail-flick apparatus and exploratory behavior, locomotion and anxiety were analyzed by open-field and plus-maze tests. We verified the total antioxidant reactivity (TAR), lipid peroxide levels by the thiobarbituric acid reactive species (TBARS) reaction and the free radicals content by the DCF test. Our results demonstrated that CPA reverted the hyperalgesia induced by hyperthyroidism and decreased the exploratory behavior, locomotion and anxiety in hyperthyroid rats. Furthermore, CPA decreased lipid peroxidation in hippocampus and cerebral cortex of control rats and in cerebral cortex of hyperthyroid rats. CPA also increased the total antioxidant reactivity in hippocampus and cerebral cortex of control and hyperthyroid rats, but the production of free radicals verified by the DCF test was changed only in cerebral cortex. These results suggest that some of the hyperthyroidism effects are subjected to regulation by adenosine A(1) receptor, demonstrating the involvement of the adenosinergic system in this pathology.

  4. Physiological roles of A1 and A2A adenosine receptors in regulating heart rate, body temperature, and locomotion as revealed using knockout mice and caffeine

    PubMed Central

    Yang, Jiang-Ning; Chen, Jiang-Fan; Fredholm, Bertil B.

    2009-01-01

    Heart rate (HR), body temperature (Temp), locomotor activity (LA), and oxygen consumption (O2C) were studied in awake mice lacking one or both of the adenosine A1 or A2A receptors (A1R or A2AR, respectively) using telemetry and respirometry, before and after caffeine administration. All parameters were lower during day than night and higher in females than males. When compared with wild-type (WT) littermates, HR was higher in male A1R knockout (A1RKO) mice but lower in A2ARKO mice and intermediate in A1-A2AR double KO mice. A single dose of an unselective β-blocker (timolol; 1 mg/kg) abolished the HR differences between these genotypes. Deletion of A1Rs had little effect on Temp, whereas deletion of A2ARs increased it in females and decreased it in males. A1-A2ARKO mice had lower Temp than WT mice. LA was unaltered in A1RKO mice and lower in A2ARKO and A1-A2ARKO mice than in WT mice. Caffeine injection increased LA but only in mice expressing A2AR. Caffeine ingestion also increased LA in an A2AR-dependent manner in male mice. Caffeine ingestion significantly increased O2C in WT mice, but less in the different KO mice. Injection of 30 mg/kg caffeine decreased Temp, especially in KO mice, and hence in a manner unrelated to A1R or A2AR blockade. Selective A2B antagonism had little or no effect. Thus A1R and A2AR influence HR, Temp, LA, and O2C in mice in a sex-dependent manner, indicating effects of endogenous adenosine. The A2AR plays an important role in the modulation of O2C and LA by acute and chronic caffeine administration. There is also evidence for effects of higher doses of caffeine being independent of both A1R and A2AR. PMID:19218506

  5. Physiological roles of A1 and A2A adenosine receptors in regulating heart rate, body temperature, and locomotion as revealed using knockout mice and caffeine.

    PubMed

    Yang, Jiang-Ning; Chen, Jiang-Fan; Fredholm, Bertil B

    2009-04-01

    Heart rate (HR), body temperature (Temp), locomotor activity (LA), and oxygen consumption (O(2)C) were studied in awake mice lacking one or both of the adenosine A(1) or A(2A) receptors (A(1)R or A(2A)R, respectively) using telemetry and respirometry, before and after caffeine administration. All parameters were lower during day than night and higher in females than males. When compared with wild-type (WT) littermates, HR was higher in male A(1)R knockout (A(1)RKO) mice but lower in A(2A)RKO mice and intermediate in A(1)-A(2A)R double KO mice. A single dose of an unselective beta-blocker (timolol; 1 mg/kg) abolished the HR differences between these genotypes. Deletion of A(1)Rs had little effect on Temp, whereas deletion of A(2A)Rs increased it in females and decreased it in males. A(1)-A(2A)RKO mice had lower Temp than WT mice. LA was unaltered in A(1)RKO mice and lower in A(2A)RKO and A(1)-A(2A)RKO mice than in WT mice. Caffeine injection increased LA but only in mice expressing A(2A)R. Caffeine ingestion also increased LA in an A(2A)R-dependent manner in male mice. Caffeine ingestion significantly increased O(2)C in WT mice, but less in the different KO mice. Injection of 30 mg/kg caffeine decreased Temp, especially in KO mice, and hence in a manner unrelated to A(1)R or A(2A)R blockade. Selective A(2B) antagonism had little or no effect. Thus A(1)R and A(2A)R influence HR, Temp, LA, and O(2)C in mice in a sex-dependent manner, indicating effects of endogenous adenosine. The A(2A)R plays an important role in the modulation of O(2)C and LA by acute and chronic caffeine administration. There is also evidence for effects of higher doses of caffeine being independent of both A(1)R and A(2A)R.

  6. Harman induces CYP1A1 enzyme through an aryl hydrocarbon receptor mechanism

    SciTech Connect

    El Gendy, Mohamed A.M.; El-Kadi, Ayman O.S., E-mail: aelkadi@pharmacy.ualberta.c

    Harman is a common compound in several foods, plants and beverages. Numerous studies have demonstrated its mutagenic, co-mutagenic and carcinogenic effects; however, the exact mechanism has not been fully identified. Aryl hydrocarbon receptor (AhR) is a transcription factor regulating the expression of the carcinogen-activating enzyme; cytochrome P450 1A1 (CYP1A1). In the present study, we examined the ability of harman to induce AhR-mediated signal transduction in human and rat hepatoma cells; HepG2 and H4IIE cells. Our results showed that harman significantly induced CYP1A1 mRNA in a time- and concentration-dependent manner. Similarly, harman significantly induced CYP1A1 at protein and activity levels inmore » a concentration-dependent manner. Moreover, the AhR antagonist, resveratrol, inhibited the increase in CYP1A1 activity by harman. The RNA polymerase inhibitor, actinomycin D, completely abolished the CYP1A1 mRNA induction by harman, indicating a transcriptional activation. The role of AhR in CYP1A1 induction by harman was confirmed by using siRNA specific for human AhR. The ability of harman to induce CYP1A1 was strongly correlated with its ability to stimulate AhR-dependent luciferase activity and electrophoretic mobility shift assay. At post-transcriptional and post-translational levels, harman did not affect the stability of CYP1A1 at the mRNA and the protein levels, excluding other mechanisms participating in the obtained effects. We concluded that harman can directly induce CYP1A1 gene expression in an AhR-dependent manner and may represent a novel mechanism by which harman promotes mutagenicity, co-mutagenicity and carcinogenicity.« less

  7. Dimerization of the EphA1 Receptor Tyrosine Kinase Transmembrane Domain: Insights into the Mechanism of Receptor Activation

    PubMed Central

    2014-01-01

    EphA1 is a receptor tyrosine kinase (RTK) that plays a key role in developmental processes, including guidance of the migration of axons and cells in the nervous system. EphA1, in common with other RTKs, contains an N-terminal extracellular domain, a single transmembrane (TM) α-helix, and a C-terminal intracellular kinase domain. The TM helix forms a dimer, as seen in recent NMR studies. We have modeled the EphA1 TM dimer using a multiscale approach combining coarse-grain (CG) and atomistic molecular dynamics (MD) simulations. The one-dimensional potential of mean force (PMF) for this system, based on interhelix separation, has been calculated using CG MD simulations. This provides a view of the free energy landscape for helix–helix interactions of the TM dimer in a lipid bilayer. The resulting PMF profiles suggest two states, consistent with a rotation-coupled activation mechanism. The more stable state corresponds to a right-handed helix dimer interacting via an N-terminal glycine zipper motif, consistent with a recent NMR structure (2K1K). A second metastable state corresponds to a structure in which the glycine zipper motif is not involved. Analysis of unrestrained CG MD simulations based on representative models from the PMF calculations or on the NMR structure reveals possible pathways of interconversion between these two states, involving helix rotations about their long axes. This suggests that the interaction of TM helices in EphA1 dimers may be intrinsically dynamic. This provides a potential mechanism for signaling whereby extracellular events drive a shift in the repopulation of the underlying TM helix dimer energy landscape. PMID:25286141

  8. S-Ketamine-Induced NMDA Receptor Blockade during Natural Speech Production and Its Implications for Formal Thought Disorder in Schizophrenia: A Pharmaco-fMRI Study.

    PubMed

    Nagels, Arne; Cabanis, Maurice; Oppel, Andrea; Kirner-Veselinovic, Andre; Schales, Christian; Kircher, Tilo

    2018-05-01

    Structural and functional changes in the lateral temporal language areas have been related to formal thought disorder (FTD) in schizophrenia. Continuous, natural speech production activates the right lateral temporal lobe in schizophrenia, as opposed to the left in healthy subjects. Positive and negative FTD can be elicited in healthy subjects by glutamatergic NMDA blockade with ketamine. It is unclear whether the glutamate system is related to the reversed hemispheric lateralization during speaking in patients. In a double-blind, crossover, placebo-controlled study, 15 healthy, male, right-handed volunteers overtly described 7 pictures for 3 min each while BOLD signal changes were acquired with fMRI. As a measure of linguistic demand, the number of words within 20 s epochs was correlated with BOLD responses. Participants developed S-ketamine-induced psychotic symptoms, particularly positive FTD. Ketamine vs placebo was associated with enhanced neural responses in the right middle and inferior temporal gyri. Similar to a previous fMRI study in schizophrenia patients vs healthy controls applying the same design, S-ketamine reversed functional lateralization during speech production in healthy subjects. Results demonstrate an association between glutamatergic imbalance, dysactivations in lateral temporal brain areas, and FTD symptom formation.

  9. 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.

  10. Irreversible blockade of sigma-1 receptors by haloperidol and its metabolites in guinea pig brain and SH-SY5Y human neuroblastoma cells.

    PubMed

    Cobos, Enrique J; del Pozo, Esperanza; Baeyens, José M

    2007-08-01

    We evaluated the effect of haloperidol (HP) and its metabolites on [(3)H](+)-pentazocine binding to sigma(1) receptors in SH-SY5Y human neuroblastoma cells and guinea pig brain P(1), P(2) and P(3) subcellular fractions. Three days after a single i.p. injection in guinea pigs of HP (but not of other sigma(1) antagonists or (-)-sulpiride), [(3)H](+)-pentazocine binding to brain membranes was markedly decreased. Recovery of sigma(1) receptor density to steady state after HP-induced inactivation required more than 30 days. HP-metabolite II (reduced HP, 4-(4-chlorophenyl)-alpha-(4-fluorophenyl)-4-hydroxy-1-piperidinebutanol), but not HP-metabolite I (4-(4-chlorophenyl)-4-hydroxypiperidine), irreversibly blocked sigma(1) receptors in guinea pig brain homogenate and P(2) fraction in vitro. We found similar results in SH-SY5Y cells, which suggests that this process may also take place in humans. HP irreversibly inactivated sigma(1) receptors when it was incubated with brain homogenate and SH-SY5Y cells, but not when incubated with P(2) fraction membranes, which suggests that HP is metabolized to inactivate sigma(1) receptors. Menadione, an inhibitor of the ketone reductase activity that leads to the production of HP-metabolite II, completely prevented HP-induced inactivation of sigma(1) receptors in brain homogenates. These results suggest that HP may irreversibly inactivate sigma(1) receptors in guinea pig and human cells, probably after metabolism to reduced HP.

  11. Enhanced tubuloglomerular feedback in mice with vascular overexpression of A1 adenosine receptors

    PubMed Central

    Oppermann, Mona; Qin, Yan; Lai, En Yin; Eisner, Christoph; Li, Lingli; Huang, Yuning; Mizel, Diane; Fryc, Justyna; Wilcox, Christopher S.; Briggs, Josephine; Schnermann, Jurgen

    2009-01-01

    Adenosine 1 receptors (A1AR) in the kidney are expressed in the vasculature and the tubular system. Pharmacological inhibition or global genetic deletion of A1AR causes marked reductions or abolishment of tubuloglomerular feedback (TGF) responses. To assess the function of vascular A1AR in TGF, we generated transgenic mouse lines in which A1AR expression in smooth muscle was augmented by placing A1AR under the control of a 5.38-kb fragment of the rat smooth muscle α-actin promoter and first intron (12). Two founder lines with highest expression in the kidney [353 ± 42 and 575 ± 43% compared with the wild type (WT)] were used in the experiments. Enhanced expression of A1AR at the expected site in these lines was confirmed by augmented constrictor responses of isolated afferent arterioles to administration of the A1AR agonist N6-cyclohexyladenosine. Maximum TGF responses (0–30 nl/min flow step) were increased from 8.4 ± 0.9 mmHg in WT (n = 21) to 14.2 ± 0.7 mmHg in A1AR-transgene (tg) 4 (n = 22; P < 0.0001), and to 12.6 ± 1.2 mmHg in A1AR-tg7 (n = 12; P < 0.02). Stepwise changes in perfusion flow caused greater numerical TGF responses in A1AR-tg than WT in all flow ranges with differences reaching levels of significance in the intermediate flow ranges of 7.5–10 and 10–15 nl/min. Proximal-distal single-nephron glomerular filtration rate (SNGFR) differences (free-flow micropuncture) were also increased in A1AR-tg, averaging 6.25 ± 1.5 nl/min compared with 2.6 ± 0.51 nl/min in WT (P = 0.034). Basal plasma renin concentrations as well as the suppression of renin secretion after volume expansion were similar in A1AR-tg and WT mice, suggesting lack of transgene expression in juxtaglomerular cells. These data indicate that A1AR expression in vascular smooth muscle cells is a critical component for TGF signaling and that changes in renal vascular A1AR expression may determine the magnitude of TGF responses. PMID:19741017

  12. Adenosine A2a blockade prevents synergy between mu-opiate and cannabinoid CB1 receptors and eliminates heroin-seeking behavior in addicted rats.

    PubMed

    Yao, Lina; McFarland, Krista; Fan, Peidong; Jiang, Zhan; Ueda, Takashi; Diamond, Ivan

    2006-05-16

    Relapse is the most serious limitation of effective medical treatment of opiate addiction. Opiate-related behaviors appear to be modulated by cannabinoid CB1 receptors (CB1) through poorly understood cross-talk mechanisms. Opiate and CB1 receptors are coexpressed in the nucleus accumbens (NAc) and dorsal striatum. These regions also have the highest density of adenosine A2a receptors (A2a) in the brain. We have been investigating the postsynaptic signaling mechanisms of mu-opiate receptors (MORs) and CB1 receptors in primary NAc/striatal neurons. In this article, we present evidence that MOR and CB1 act synergistically on cAMP/PKA signaling in NAc/striatal neurons. In addition, we find that synergy requires adenosine and A2a. Importantly, an A2a antagonist administered either directly into the NAc or indirectly by i.p. injection eliminates heroin-induced reinstatement in rats trained to self-administer heroin, a model of human craving and relapse. These findings suggest that A2a antagonists might be effective therapeutic agents in the management of abstinent heroin addicts.

  13. Adenosine A2a blockade prevents synergy between μ-opiate and cannabinoid CB1 receptors and eliminates heroin-seeking behavior in addicted rats

    PubMed Central

    Yao, Lina; McFarland, Krista; Fan, Peidong; Jiang, Zhan; Ueda, Takashi; Diamond, Ivan

    2006-01-01

    Relapse is the most serious limitation of effective medical treatment of opiate addiction. Opiate-related behaviors appear to be modulated by cannabinoid CB1 receptors (CB1) through poorly understood cross-talk mechanisms. Opiate and CB1 receptors are coexpressed in the nucleus accumbens (NAc) and dorsal striatum. These regions also have the highest density of adenosine A2a receptors (A2a) in the brain. We have been investigating the postsynaptic signaling mechanisms of μ-opiate receptors (MORs) and CB1 receptors in primary NAc/striatal neurons. In this article, we present evidence that MOR and CB1 act synergistically on cAMP/PKA signaling in NAc/striatal neurons. In addition, we find that synergy requires adenosine and A2a. Importantly, an A2a antagonist administered either directly into the NAc or indirectly by i.p. injection eliminates heroin-induced reinstatement in rats trained to self-administer heroin, a model of human craving and relapse. These findings suggest that A2a antagonists might be effective therapeutic agents in the management of abstinent heroin addicts. PMID:16684876

  14. Anticonvulsant effect of AMP by direct activation of adenosine A1 receptor.

    PubMed

    Muzzi, Mirko; Coppi, Elisabetta; Pugliese, Anna Maria; Chiarugi, Alberto

    2013-12-01

    Purinergic neurotransmission mediated by adenosine (Ado) type 1 receptors (A1Rs) plays pivotal roles in negative modulation of epileptic seizures, and Ado is thought to be a key endogenous anticonvulsant. Recent evidence, however, indicates that AMP, the metabolic precursor of Ado, also activate A1Rs. Here, we evaluated the antiepileptic effects of AMP adopting in vitro and in vivo models of epilepsy. We report that AMP reversed the increase in population spike (PS) amplitude and the decrease in PS latency induced by a Mg(2+)-free extracellular solution in CA1 neurons of mouse hippocampal slices. The AMP effects were inhibited by the A1R antagonist DPCPX, but not prevented by inhibiting conversion of AMP into Ado, indicating that AMP inhibited per se sustained hippocampal excitatory neurotransmission by directly activating A1Rs. AMP also reduced seizure severity and mortality in a model of audiogenic convulsion. Of note, the anticonvulsant effects of AMP were potentiated by preventing its conversion into Ado and inhibited by DPCPX. When tested in a model of kainate-induced seizure, AMP prolonged latency of convulsions but had no effects on seizure severity and mortality. Data provide the first evidence that AMP is an endogenous anticonvulsant acting at A1Rs. © 2013.

  15. The ACE-2/Ang1-7/Mas cascade enhances bone structure and metabolism following angiotensin-II type 1 receptor blockade.

    PubMed

    Abuohashish, Hatem M; Ahmed, Mohammed M; Sabry, Dina; Khattab, Mahmoud M; Al-Rejaie, Salim S

    2017-07-15

    The renin angiotensin system (RAS) regulates numerous systemic functions and is expressed locally in skeletal tissues. Angiotensin1-7 (Ang1-7) is a beneficial member of the RAS, and the therapeutic effects of a large number of angiotensin receptors blockers (ARBs) are mediated by an Ang1-7-dependent cascade. This study examines whether the reported osteo-preservative effects of losartan are mediated through the angiotensin converting enzyme2 (ACE-2)/Ang1-7/Mas pathway in ovariectomized (OVX) rats. Sham and OVX animals received losartan (10mg/kg/d p.o.) for 6 weeks. A specific Mas receptor blocker (A-779) was delivered via mini-osmotic pumps during the losartan treatment period. Serum and urine bone metabolism biomarker levels were measured. Bone trabecular and cortical morphometry were quantified in distal femurs, whereas mineral contents were estimated in ashed bones, serum and urine. Finally, the expression of RAS components, the receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) was determined. Losartan significantly improved the elevated bone metabolism marker levels and altered trabecular and cortical structures in OVX animals, and restored normal urinary and skeletal mineral levels. Mas receptor inhibition significantly abolished all osteo-protective effects of losartan and enhanced the deleterious effects of OVX. Losartan enhanced OVX-induced up-regulation of ACE-1, AngII, angiotensin type 1 (AT 1 ) receptor and RANKL expression, and increased ACE-2, Ang1-7, Mas and OPG expression in OVX animals. However, A-779 significantly eradicated the effects of losartan on RAS components and RANKL/OPG expression. Thus, Ang1-7 are involved in the osteo-preservative effects of losartan via Mas receptor, which may add therapeutic value to this well-known antihypertensive agent. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Blockade of CB1 receptors prevents retention of extinction but does not increase low preincubated conditioned fear in the fear incubation procedure.

    PubMed

    Pickens, Charles L; Theberge, Florence R

    2014-02-01

    We recently developed a procedure to study fear incubation, in which rats given 100 tone-shock pairings over 10 days show low fear 2 days after conditioned fear training and high fear after 30 days. Notably, fear 2 days after 10 sessions of fear conditioning is lower than fear seen 2 days after a single session of fear conditioning, suggesting that fear is suppressed. Here, we investigate the potential role of CB1 receptor activation by endocannabinoids in this fear suppression. We subjected rats to 10 days of fear conditioning and then administered systemic injections of the CB1 receptor antagonist SR141716 before a conditioned fear test was conducted 2 days later under extinction conditions. A second test was conducted without any injections on the following day (3 days after training) to examine retention of fear extinction. SR141716 injections did not increase fear expression 2 days after extended fear conditioning or affect within-session extinction; however, it impaired retention of between-session fear extinction in the day 3 test. These data suggest that CB1 receptor activation does not suppress fear soon after extended fear conditioning in the fear incubation task. The data also add to the existing literature on the role of CB1 receptors in extinction of conditioned fear.

  17. Blockade of CB1 receptors prevents retention of extinction but does not increase low pre-incubated conditioned fear in the fear incubation procedure

    PubMed Central

    Pickens, Charles L.; Theberge, Florence R.

    2015-01-01

    We recently developed a procedure to study fear incubation in which rats given 100 tone-shock pairings over 10 days show low fear 2 days after conditioned fear training and high fear after 30 days. Notably, fear 2 days after 10 sessions of fear conditioning is lower than fear seen 2 days after a single session of fear conditioning, suggesting that fear is suppressed. Here, we investigate the potential role of CB1 receptor activation by endocannabinoids in this fear suppression. We gave rats 10 days of fear conditioning and then gave systemic injections of the CB1 receptor antagonist SR141716 before a conditioned fear test conducted 2 days later under extinction conditions. A second test was conducted without any injections on the following day (3 days post-training) to examine fear extinction retention. SR141716 injections did not increase fear expression 2 days after extended fear conditioning or affect within-session extinction, but impaired retention of between-session fear extinction in the day 3 test. These data suggest that CB1 receptor activation is not suppressing fear soon after extended fear conditioning in the fear incubation task. The data also add to an existing literature on the effects of CB1 receptors in extinction of conditioned fear. PMID:24346290

  18. An immunocapture/scintillation proximity analysis of G alpha q/11 activation by native serotonin (5-HT)2A receptors in rat cortex: blockade by clozapine and mirtazapine.

    PubMed

    Mannoury La Cour, C; Chaput, C; Touzard, M; Millan, M J

    2009-02-01

    Though transduction mechanisms recruited by heterologously expressed 5-HT(2A) receptors have been extensively studied, their interaction with specific subtypes of G-protein remains to be directly evaluated in cerebral tissue. Herein, as shown by an immunocapture/scintillation proximity analysis, 5-HT, the prototypical 5-HT(2A) agonist, DOI, and Ro60,0175 all enhanced [(35)S]GTPgammaS binding to G alpha q/11 in rat cortex with pEC(50) values of 6.22, 7.24 and 6.35, respectively. No activation of G o or G s/olf was seen at equivalent concentrations of DOI. Stimulation of G alpha q/11 by 5-HT (30 microM) and DOI (30 microM) was abolished by the selective 5-HT(2A) vs. 5-HT(2C)/5-HT(2B) antagonists, ketanserin (pK(B) values of 9.11 and 8.88, respectively) and MDL100,907 (9.82 and 9.68). By contrast, 5-HT-induced [(35)S]GTPgammaS binding to G alpha q/11 was only weakly inhibited by the preferential 5-HT(2C) receptor antagonists, RS102,221 (6.94) and SB242,084 (7.39), and the preferential 5-HT(2B) receptor antagonist, LY266,097 (6.66). The antipsychotic, clozapine, which had marked affinity for 5-HT(2A) receptors, blocked the recruitment of G alpha q/11 by 5-HT and DOI with pK(B) values of 8.54 and 8.14, respectively. Its actions were mimicked by the "atypical" antidepressant and 5-HT(2A) receptor antagonist, mirtazapine, which likewise blocked 5-HT and DOI-induced G alpha q/11 protein activation with pK(B) values of 7.90 and 7.76, respectively. In conclusion, by use of an immunocapture/scintillation proximity strategy, this study shows that native 5-HT(2A) receptors in rat frontal cortex specifically recruit G alpha q/11 and that this action is blocked by clozapine and mirtazapine. Quantification of 5-HT(2A) receptor-mediated G alpha q/11 activation in frontal cortex should prove instructive in characterizing the actions of diverse classes of psychotropic agent. 2008 Wiley-Liss, Inc.

  19. AMP-guided tumour-specific nanoparticle delivery via adenosine A1 receptor.

    PubMed

    Dai, Tongcheng; Li, Na; Han, Fajun; Zhang, Hua; Zhang, Yuanxing; Liu, Qin

    2016-03-01

    Active targeting-ligands have been increasingly used to functionalize nanoparticles for tumour-specific clinical applications. Here we utilize nucleotide adenosine 5'-monophosphate (AMP) as a novel ligand to functionalize polymer-based fluorescent nanoparticles (NPs) for tumour-targeted imaging. We demonstrate that AMP-conjugated NPs (NPs-AMP) efficiently bind to and are following internalized into colon cancer cell CW-2 and breast cancer cell MDA-MB-468 in vitro. RNA interference and inhibitor assays reveal that the targeting effects mainly rely on the specific binding of AMP to adenosine A1 receptor (A1R), which is greatly up-regulated in cancer cells than in matched normal cells. More importantly, NPs-AMP specifically accumulate in the tumour site of colon and breast tumour xenografts and are further internalized into the tumour cells in vivo via tail vein injection, confirming that the high in vitro specificity of AMP can be successfully translated into the in vivo efficacy. Furthermore, NPs-AMP exhibit an active tumour-targeting behaviour in various colon and breast cancer cells, which is positively related to the up-regulation level of A1R in cancer cells, suggesting that AMP potentially suits for more extensive A1R-overexpressing cancer models. This work establishes AMP to be a novel tumour-targeting ligand and provides a promising strategy for future diagnostic or therapeutic applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Opioid/NMDA receptors blockade reverses the depressant-like behavior of foot shock stress in the mouse forced swimming test.

    PubMed

    Haj-Mirzaian, Arya; Ostadhadi, Sattar; Kordjazy, Nastaran; Dehpour, Ahmad Reza; Ejtemaei Mehr, Shahram

    2014-07-15

    Opioid and glutamatergic receptors have a key role in depression following stress. In this study, we assessed opioid and glutamatergic receptors interaction with the depressant-like behavior of acute foot-shock stress in the mouse forced swimming test. Stress was induced by intermittent foot shock stimulation during 30min and swim periods were afterwards conducted by placing mice in separated glass cylinders filled with water for 6min. The immobility time during the last 4min of the test was considered. Acute foot-shock stress significantly increased the immobility time of mice compared to non-stressed control group (P≤0.01). Administration of non-selective opioid receptors antagonist, naltrexone (1 and 2mg/kg, i.p.), and the selective non-competitive NMDA receptor antagonist, MK-801 (0.05mg/kg, i.p.), and the selective serotonin reuptake inhibitor, fluoxetine (5mg/kg), significantly reduced the immobility time in stressed animals (P≤0.01). Lower doses of MK-801 (0.01mg/kg), naltrexone (0.3mg/kg), NMDA (75mg/kg) and morphine(5mg/kg) had no effect on foot-shock stressed mice. Combined treatment of sub-effective doses of naltrexone and MK-801 significantly showed an antidepressant-like effect (P≤0.001). On the other hand, co-administration of non-effective doses of NMDA and morphine with effective doses of naltrexone and MK-801 reversed the anti-immobility effect of these drugs. Taken together, we have for the first time demonstrated the possible role of opioid/NMDA receptors signaling in the depressant-like effect of foot-shock stress, and proposed the use of drugs that act like standard anti-depressants in stress-induced depression. Copyright © 2014. Published by Elsevier B.V.

  1. Posttranscriptional mRNA processing as a mechanism for regulation of human A1 adenosine receptor expression.

    PubMed Central

    Ren, H; Stiles, G L

    1994-01-01

    The human A1 adenosine receptor gene contains six exons with exons 1, 2, 3, 4, and part of 5 representing 5' untranslated regions. Reverse transcription-PCR with exon-specific primers showed two distinct transcripts containing either exons 3, 5, and 6 or exons 4, 5, and 6, with exons 3 and 4 being mutually exclusive. No mature mRNAs containing exons 1 and 2 have been detected. All human tissues that express any A1 receptors contain mRNA with exons 4, 5, and 6. Tissues which express high levels of A1 receptors contain mRNA with exons 3, 5, and 6. Exon 4 contains two upstream ATG codons whereas exon 3 contains none. COS cells transfected with expression vectors containing exon 4 (exons 1-6, 3-6, or Ex4-6) express much lower levels of A1 receptors than vectors without exon 4 (exons 3, 5, and 6). Mutation of upstream ATG codons in exon 4 leads to 3- to 7-fold increased A1 receptor expression, up to the level seen with the construct containing exons 3, 5, and 6. Thus, in human tissues "basal" levels of A1 receptors can be expressed by use of mRNA containing exons 4, 5, and 6, but when high levels are needed, alternative transcripts with exons 3, 5, and 6 are produced. Images PMID:8197148

  2. New Drug Candidate Targeting the 4A1 Orphan Nuclear Receptor for Medullary Thyroid Cancer Therapy.

    PubMed

    Zhang, Lei; Liu, Wen; Wang, Qun; Li, Qinpei; Wang, Huijuan; Wang, Jun; Teng, Tieshan; Chen, Mingliang; Ji, Ailing; Li, Yanzhang

    2018-03-02

    Medullary thyroid cancer (MTC) is a relatively rare thyroid cancer responsible for a substantial fraction of thyroid cancer mortality. More effective therapeutic drugs with low toxicity for MTC are urgently needed. Orphan nuclear receptor 4A1 (NR4A1) plays a pivotal role in regulating the proliferation and apoptosis of a variety of tumor cells. Based on the NR4A1 protein structure, 2-imino-6-methoxy-2H-chromene-3-carbothioamide (IMCA) was identified from the Specs compounds database using the protein structure-guided virtual screening approach. Computationally-based molecular modeling studies suggested that IMCA has a high affinity for the ligand binding pocket of NR4A1. MTT [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide] and apoptosis assays demonstrated that IMCA resulted in significant thyroid cancer cell death. Immunofluorescence assays showed that IMCA induced NR4A1 translocation from the nucleus to the cytoplasm in thyroid cancer cell lines, which may be involved in the cell apoptotic process. In this study, the quantitative polymerase chain reaction results showed that the IMCA-induced upregulation of sestrin1 and sestrin2 was dose-dependent in thyroid cancer cell lines. Western blot showed that IMCA increased phosphorylation of adenosine 5'-monophosphate-activated protein kinase (AMPK) and decreased phosphorylation of ribosomal protein S6 kinase (p70S6K), which is the key enzyme in the mammalian target of rapamycin (mTOR) pathway. The experimental results suggest that IMCA is a drug candidate for MTC therapy and may work by increasing the nuclear export of NR4A1 to the cytoplasm and the tumor protein 53 (p53)-sestrins-AMPK-mTOR signaling pathway.

  3. Systemic blockade of LPA1/3 lysophosphatidic acid receptors by ki16425 modulates the effects of ethanol on the brain and behavior.

    PubMed

    Sánchez-Marín, Laura; Ladrón de Guevara-Miranda, David; Mañas-Padilla, M Carmen; Alén, Francisco; Moreno-Fernández, Román D; Díaz-Navarro, Caridad; Pérez-Del Palacio, José; García-Fernández, María; Pedraza, Carmen; Pavón, Francisco J; Rodríguez de Fonseca, Fernando; Santín, Luis J; Serrano, Antonia; Castilla-Ortega, Estela

    2018-05-01

    The systemic administration of lysophosphatidic acid (LPA) LPA 1/3 receptor antagonists is a promising clinical tool for cancer, sclerosis and fibrosis-related diseases. Since LPA 1 receptor-null mice engage in increased ethanol consumption, we evaluated the effects of systemic administration of an LPA 1/3 receptor antagonist (intraperitoneal ki16425, 20 mg/kg) on ethanol-related behaviors as well as on brain and plasma correlates. Acute administration of ki16425 reduced motivation for ethanol but not for saccharine in ethanol self-administering Wistar rats. Mouse experiments were conducted in two different strains. In Swiss mice, ki16425 treatment reduced both ethanol-induced sedation (loss of righting reflex, LORR) and ethanol reward (escalation in ethanol consumption and ethanol-induced conditioned place preference, CPP). Furthermore, in the CPP-trained Swiss mice, ki16425 prevented the effects of ethanol on basal c-Fos expression in the medial prefrontal cortex and on adult neurogenesis in the hippocampus. In the c57BL6/J mouse strain, however, no effects of ki16425 on LORR or voluntary drinking were observed. The c57BL6/J mouse strain was then evaluated for ethanol withdrawal symptoms, which were attenuated when ethanol was preceded by ki16425 administration. In these animals, ki16425 modulated the expression of glutamate-related genes in brain limbic regions after ethanol exposure; and peripheral LPA signaling was dysregulated by either ki16425 or ethanol. Overall, these results suggest that LPA 1/3 receptor antagonists might be a potential new class of drugs that are suitable for treating or preventing alcohol use disorders. A pharmacokinetic study revealed that systemic ki16425 showed poor brain penetration, suggesting the involvement of peripheral events to explain its effects. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Blockade of 5-HT2A/2C-type receptors impairs learning in female rats in the course of estrous cycle.

    PubMed

    Fedotova, Yu O; Ordyan, N E

    2010-12-01

    We studied the effects of chronic administration (14 days) of agonist of 5-HT2B/2C serotonin receptors m-CPP (0.5 mg/kg subcutaneously) and agonist of 5-HT2A/2C serotonin receptors ketanserin (0.1 mg/kg intraperitoneally) on conditioned reactions in female rats in different phases of the estrous cycle. Passive avoidance (PA) paradigm and Morris water maze were used as behavioral tests. Chronic administration of m-CPP did not affect PA retrieval during the proestrus and estrus phases, but improved the dynamics of spatial learning in Morris water maze in comparison with control rats. Chronic administration of ketanserin uniformly impaired processes of spatial and nonspatial learning in female rats irrespective to the phase of the estrous cycle. A modulating role of 5-HT2A/2C and 5-HT2B/2C serotonin receptors in process of learning in female rats during the key phases of the estrous cycle was demonstrated.

  5. Blockade of GABA, type A, receptors in the rat pontine reticular formation induces rapid eye movement sleep that is dependent upon the cholinergic system.

    PubMed

    Marks, G A; Sachs, O W; Birabil, C G

    2008-09-22

    The brainstem reticular formation is an area important to the control of rapid eye movement (REM) sleep. The antagonist of GABA-type A (GABA(A)) receptors, bicuculline methiodide (BMI), injected into the rat nucleus pontis oralis (PnO) of the reticular formation resulted in a long-lasting increase in REM sleep. Thus, one factor controlling REM sleep appears to be the number of functional GABA(A) receptors in the PnO. The long-lasting effect produced by BMI may result from secondary influences on other neurotransmitter systems known to have long-lasting effects. To study this question, rats were surgically prepared for chronic sleep recording and additionally implanted with guide cannulas aimed at sites in the PnO. Multiple, 60 nl, unilateral injections were made either singly or in combination. GABA(A) receptor antagonists, BMI and gabazine (GBZ), produced dose-dependent increases in REM sleep with GBZ being approximately 35 times more potent than BMI. GBZ and the cholinergic agonist, carbachol, produced very similar results, both increasing REM sleep for about 8 h, mainly through increased period frequency, with little reduction in REM latency. Pre-injection of the muscarinic antagonist, atropine, completely blocked the REM sleep-increase by GBZ. GABAergic control of REM sleep in the PnO requires the cholinergic system and may be acting through presynaptic modulation of acetylcholine release.

  6. [Adoptive Cell Therapy with Immune Checkpoint Blockade].

    PubMed

    Aruga, Atsushi

    2017-09-01

    Cancer immunotherapy are taking a leading role of cancer therapy due to the development of the immune checkpoint blockade. To date, however, only about 20% of patients have clinical responses and the cancer-specific T cells in cancer site are required to obtain beneficial effects. There has been an innovative development in the field of adoptive cell therapy, especially receptor gene-modified T cells in recent years. The effector cells mostly express PD-1, therefore the cytotoxic reactivity of the effector cells are inhibited by PD-L1. The combination of the adoptive cell therapy and the immune checkpoint blockade is expected to enhance efficacy. On the other hand, the immune-related adverse events may also be enhanced, therefore, it is needed to develop the combination therapy carefully, improving the cancer antigen-specificity or dealing with the cytokine release syndrome.

  7. Valerian extract Ze 911 inhibits postsynaptic potentials by activation of adenosine A1 receptors in rat cortical neurons.

    PubMed

    Vissiennon, Z; Sichardt, K; Koetter, U; Brattström, A; Nieber, K

    2006-06-01

    In this study we evaluated the adenosine A1 receptor-mediated effect of valerian extract (Ze 911) on postsynaptic potentials (PSPs) in pyramidal cells of the rat cingulate cortex in a slice preparation. We first observed that N6-cyclopentyladenosine (CPA, 0.01 - 10 microM), an adenosine A1 receptor agonist, inhibited PSPs in a concentration-dependent manner. The CPA (10 microM)-induced inhibition was antagonized by 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 0.1 microM), an adenosine A1 receptor antagonist. Ze 911 concentration dependently (0.1 - 15 mg/mL) inhibited PSPs in the presence of the adenosine A2A receptor antagonist 1,3,7-trimethyl-8-(3-chlorostyryl)xanthine (CSC, 0.2 microM) and adenosine deaminase (1 U/mL). The maximal inhibition induced by 10 mg/mL was completely antagonised by DPCPX (0.1 microM), an A1 receptor blocker. The data suggest that activation of adenosine A1 receptors is involved in the pharmacological effects of the valerian extract Ze 911.

  8. Lack of effect of nucleus accumbens dopamine D1 receptor blockade on consumption during the first two days of operant self-administration of sweetened ethanol in adult Long-Evans rats.

    PubMed

    Doherty, James M; Gonzales, Rueben A

    2015-09-01

    The mechanisms underlying ethanol self-administration are not fully understood; however, it is clear that ethanol self-administration stimulates nucleus accumbens dopamine release in well-trained animals. During operant sweetened ethanol self-administration behavior, an adaptation in the nucleus accumbens dopamine system occurs between the first and second exposure, paralleling a dramatic increase in sweetened ethanol intake, which suggests a single exposure to sweetened ethanol may be sufficient to learn the association between sweetened ethanol cues and its reinforcing properties. In the present experiment, we test the effects of blockade of nucleus accumbens dopamine D1 receptors on operant sweetened ethanol self-administration behavior during the first 2 days of exposure. Adult male Long-Evans rats were first trained to self-administer 10% sucrose (10S) across 6 days in an appetitive and consummatory operant model (appetitive interval: 10-min pre-drinking wait period and a lever response requirement of 4; consummatory interval: 20-min access to the drinking solution). After training on 10S, the drinking solution was switched to 10% sucrose plus 10% ethanol (10S10E); control rats continued drinking 10S throughout the experiment. Bilateral nucleus accumbens microinjections of the dopamine D1 antagonist, SCH-23390 (0, 1.0, or 3.0 μg/side), immediately preceded the first two sessions of drinking 10S10E. Results show that blocking nucleus accumbens dopamine D1 receptors has little or no influence on consumption during the first 2 days of exposure to the sweetened ethanol solution or maintenance of sucrose-only drinking. Furthermore, the high dose of SCH-23390, 3.0 μg/side, reduced open-field locomotor activity. In conclusion, we found no evidence to suggest that nucleus accumbens D1 receptor activation is involved in consumption of a sweetened ethanol solution during the first 2 days of exposure or maintenance of sucrose drinking, but rather D1 receptors seem

  9. Evaluation of the counter-regulatory responses to hypoglycaemia in patients with type 1 diabetes during opiate receptor blockade with naltrexone.

    PubMed

    Naik, Sarita; Belfort-DeAguiar, Renata; Sejling, Anne-Sophie; Szepietowska, Barbara; Sherwin, Robert S

    2017-05-01

    Hypoglycaemia is the major limiting factor in achieving optimal glycaemic control in people with type 1 diabetes (T1DM), especially intensively treated patients with impaired glucose counter-regulation during hypoglycaemia. Naloxone, an opiate receptor blocker, has been reported to enhance the acute counter-regulatory response to hypoglycaemia when administered intravenously in humans. The current study was undertaken to investigate the oral formulation of the long-acting opiate antagonist, naltrexone, and determine if it could have a similar effect, and thus might be useful therapeutically in treatment of T1DM patients with a high risk of hypoglycaemia. We performed a randomized, placebo-controlled, double-blinded, cross-over study in which 9 intensively treated subjects with T1DM underwent a 2-step euglycaemic-hypoglycaemic-hyperinsulinaemic clamp on 2 separate occasions. At 12 hours and at 1 hour before the clamp study, participants received 100 mg of naltrexone or placebo orally. Counter-regulatory hormonal responses were assessed at baseline and during each step of the hyperinsulinaemic-clamp. Glucose and insulin levels did not differ significantly between the naltrexone and placebo visits; nor did the glucose infusion rates required to keep glucose levels at target. During hypoglycaemia, naltrexone, in comparison with the placebo group, induced an increase in epinephrine levels ( P  = .05). However, no statistically significant differences in glucagon, cortisol and growth hormone responses were observed. In contrast to the intravenous opiate receptor blocker naloxone, overnight administration of the oral long-acting opiate receptor blocker, naltrexone, at a clinically used dose, had a limited effect on the counter-regulatory response to hypoglycaemia in intensively treated subjects with T1DM. © 2016 John Wiley & Sons Ltd.

  10. Impaired Vascular Contractility and Aortic Wall Degeneration in Fibulin-4 Deficient Mice: Effect of Angiotensin II Type 1 (AT1) Receptor Blockade

    PubMed Central

    Moltzer, Els; te Riet, Luuk; Swagemakers, Sigrid M. A.; van Heijningen, Paula M.; Vermeij, Marcel; van Veghel, Richard; Bouhuizen, Angelique M.; van Esch, Joep H. M.; Lankhorst, Stephanie; Ramnath, Natasja W. M.; de Waard, Monique C.; Duncker, Dirk J.; van der Spek, Peter J.; Rouwet, Ellen V.; Danser, A. H. Jan; Essers, Jeroen

    2011-01-01

    Medial degeneration is a key feature of aneurysm disease and aortic dissection. In a murine aneurysm model we investigated the structural and functional characteristics of aortic wall degeneration in adult fibulin-4 deficient mice and the potential therapeutic role of the angiotensin (Ang) II type 1 (AT1) receptor antagonist losartan in preventing aortic media degeneration. Adult mice with 2-fold (heterozygous Fibulin-4+/R) and 4-fold (homozygous Fibulin-4R/R) reduced expression of fibulin-4 displayed the histological features of cystic media degeneration as found in patients with aneurysm or dissection, including elastin fiber fragmentation, loss of smooth muscle cells, and deposition of ground substance in the extracellular matrix of the aortic media. The aortic contractile capacity, determined by isometric force measurements, was diminished, and was associated with dysregulation of contractile genes as shown by aortic transcriptome analysis. These structural and functional alterations were accompanied by upregulation of TGF-β signaling in aortas from fibulin-4 deficient mice, as identified by genome-scaled network analysis as well as by immunohistochemical staining for phosphorylated Smad2, an intracellular mediator of TGF-β. Tissue levels of Ang II, a regulator of TGF-β signaling, were increased. Prenatal treatment with the AT1 receptor antagonist losartan, which blunts TGF-β signaling, prevented elastic fiber fragmentation in the aortic media of newborn Fibulin-4R/R mice. Postnatal losartan treatment reduced haemodynamic stress and improved lifespan of homozygous knockdown fibulin-4 animals, but did not affect aortic vessel wall structure. In conclusion, the AT1 receptor blocker losartan can prevent aortic media degeneration in a non-Marfan syndrome aneurysm mouse model. In established aortic aneurysms, losartan does not affect aortic architecture, but does improve survival. These findings may extend the potential therapeutic application of inhibitors of

  11. Differential effect of opioid and cannabinoid receptor blockade on heroin-seeking reinstatement and cannabinoid substitution in heroin-abstinent rats

    PubMed Central

    Fattore, L; Spano, MS; Melis, V; Fadda, P; Fratta, W

    2011-01-01

    BACKGROUND AND PURPOSE Opioids and cannabinoids interact in drug addiction and relapse. We investigated the effect of the opioid receptor antagonist naloxone and/or the cannabinoid CB1 receptor antagonist rimonabant on cannabinoid-induced reinstatement of heroin seeking and on cannabinoid substitution in heroin-abstinent rats. EXPERIMENTAL APPROACH Rats were trained to self-administer heroin (30 µg·kg−1 per infusion) under a fixed-ratio 1 reinforcement schedule. After extinction of self-administration (SA) behaviour, we confirmed the effect of naloxone (0.1–1 mg·kg−1) and rimonabant (0.3–3 mg·kg−1) on the reinstatement of heroin seeking induced by priming with the CB1 receptor agonist WIN55,212-2 (WIN, 0.15–0.3 mg·kg−1). Then, in a parallel set of heroin-trained rats, we evaluated whether WIN (12.5 µg·kg−1 per infusion) SA substituted for heroin SA after different periods of extinction. In groups of rats in which substitution occurred, we studied the effect of both antagonists on cannabinoid intake. KEY RESULTS Cannabinoid-induced reinstatement of heroin seeking was significantly attenuated by naloxone (1 mg·kg−1) and rimonabant (3 mg·kg−1) and fully blocked by co-administration of sub-threshold doses of the two antagonists. Moreover, contrary to immediate (1 day) or delayed (90 days) drug substitution, rats readily self-administered WIN when access was given after 7, 14 or 21 days of extinction from heroin, and showed a response rate that was positively correlated with the extinction period. In these animals, cannabinoid intake was increased by naloxone (1 mg·kg−1) and decreased by rimonabant (3 mg·kg−1). CONCLUSIONS AND IMPLICATIONS Our findings extend previous research on the crosstalk between cannabinoid and opioid receptors in relapse mechanisms, which suggests a differential role in heroin-seeking reinstatement and cannabinoid substitution in heroin-abstinent rats. LINKED ARTICLES This article is part of a themed issue on

  12. Role of central and peripheral adenosine receptors in the cardiovascular responses to intraperitoneal injections of adenosine A1 and A2A subtype receptor agonists.

    PubMed

    Schindler, Charles W; Karcz-Kubicha, Marzena; Thorndike, Eric B; Müller, Christa E; Tella, Srihari R; Ferré, Sergi; Goldberg, Steven R

    2005-03-01

    1. The cardiovascular effects of the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) and the adenosine A2A receptor agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine (CGS 21680) were investigated in rats implanted with telemetry transmitters for the measurement of blood pressure and heart rate. 2. Intraperitoneal (i.p.) injections of the adenosine A1 receptor agonist CPA led to dose-dependent decreases in both blood pressure and heart rate. These effects of 0.3 mg kg(-1) CPA were antagonized by i.p. injections of the adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dimethyl-xanthine (CPT), but not by i.p. injections of the adenosine A2A receptor antagonist 3-(3-hydroxypropyl)-8-(m-methoxystyryl)-7-methyl-1-propargylxanthine phosphate disodium salt (MSX-3). Injections (i.p.) of the peripherally acting nonselective adenosine antagonist 8-sulfophenyltheophylline (8-SPT) and the purported nonselective adenosine antagonist caffeine also antagonized the cardiovascular effects of CPA. 3. The adenosine A2A agonist CGS 21680 given i.p. produced a dose-dependent decrease in blood pressure and an increase in heart rate. These effects of 0.5 mg kg(-1) CGS 21680 were antagonized by i.p. injections of the adenosine A2A receptor antagonist MSX-3, but not by i.p. injections of the antagonists CPT, 8-SPT or caffeine. 4. Central administration (intracerebral ventricular) of CGS 21680 produced an increase in heart rate, but no change in blood pressure. MSX-3 given i.p. antagonized the effects of the central injection of CGS 21680. 5. These results suggest that adenosine A1 receptor agonists produce decreases in blood pressure and heart rate that are mediated by A1 receptors in the periphery, with little or no contribution of central adenosine A1 receptors to those effects. 6. The heart rate increasing effect of adenosine A2A agonists appears to be mediated by adenosine A2A receptors in the central nervous system. The blood pressure decreasing

  13. 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.

  14. Norepinephrine infusion with and without alpha-adrenergic blockade by phentolamine increases salivary alpha amylase in healthy men.

    PubMed

    Kuebler, Ulrike; von Känel, Roland; Heimgartner, Nadja; Zuccarella-Hackl, Claudia; Stirnimann, Guido; Ehlert, Ulrike; Wirtz, Petra H

    2014-11-01

    Mental stress reliably induces increases in salivary alpha amylase (sAA), a suggested surrogate marker for sympathetic nervous system (SNS) reactivity. While stress-induced sAA increases correlate with norepinephrine (NE) secretion, a potential mediating role of noradrenergic mechanisms remains unclear. In this study, we investigated for the first time in humans whether a NE-stress-reactivity mimicking NE-infusion with and without alpha-adrenergic blockade by phentolamine would induce changes in sAA. In a single-blind placebo-controlled within-subjects design, 21 healthy men (29-66 years) took part in three different experimental trials varying in terms of substance infusion with a 1-min first infusion followed by a 15-min second infusion: saline-infusion (trial-1), NE-infusion (5 μg/min) without alpha-adrenergic blockade (trial-2), and with phentolamine-induced non-selective blockade of alpha1- and alpha2-adrenergic receptors (trial-3). Saliva samples were collected immediately before, during, and several times after substance infusion in addition to blood pressure and heart rate readings. Experimental trials significantly differed in sAA reactivity to substance-infusion (p=.001) with higher sAA reactivity following NE-infusion with (trial-3; p=.001) and without alpha-adrenergic-blockade (trial-2; p=.004) as compared to placebo-infusion (trial-1); sAA infusion reactivity did not differ between trial-2 and trial-3 (p=.29). Effective phentolamine application was verified by blood pressure and heart rate infusion reactivity. Salivary cortisol was not affected by NE, either with or without alpha-adrenergic-blockade. We found that NE-infusion stimulates sAA secretion, regardless of co-administered non-selective alpha-adrenergic blockade by phentolamine, suggesting that the mechanism underlying stress-induced sAA increases may involve NE. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Therapeutic efficacy of the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) against organophosphate intoxication.

    PubMed

    Bueters, Tjerk J H; Groen, Bas; Danhof, Meindert; IJzerman, Ad P; Van Helden, Herman P M

    2002-11-01

    The objective of the present study was to investigate whether reduction of central acetylcholine (ACh) accumulation by adenosine receptor agonists could serve as a generic treatment against organophosphate (OP) poisoning. The OPs studied were tabun ( O-ethyl- N-dimethylphosphoramidocyanidate), sarin (isopropylmethylphosphonofluoridate), VX ( O-ethyl- S-2-diisopropylaminoethylmethylphosphonothiolate) and parathion ( O, O-diethyl- O-(4-nitrophenyl)phosphorothioate). The efficacy of the adenosine A(1) receptor agonist N(6)-cyclopentyladenosine (CPA) against an OP intoxication was examined on the basis of the occurrence of clinical symptoms that are directly associated with such intoxication. CPA (1-2 mg/kg) effectively attenuated the cholinergic symptoms and prevented mortality in lethally tabun- or sarin-intoxicated rats. In contrast, CPA (2 mg/kg) proved to be ineffective against VX or parathion intoxication. Intracerebral microdialysis studies revealed that survival of sarin-poisoned and CPA-treated animals coincided with a minor elevation of extracellular ACh concentrations in the brain relative to the baseline value, whereas an 11-fold increase in transmitter levels was observed in animals not treated with CPA. In VX-intoxicated rats, however, the ACh amounts increased 18-fold, irrespective of treatment with CPA. The striatal acetylcholinesterase (AChE) activity following a lethal sarin intoxication was completely abolished in the vehicle-treated animals, whereas 10% and 60% AChE activity remained in animals treated with 2 mg/kg CPA 1 min after or 2 min prior to the poisoning, respectively. In VX-intoxicated animals the AChE activity in the brain was strongly reduced (striatum 10%, hippocampus 1%) regardless of the CPA treatment. These results demonstrate that CPA is highly effective against tabun or sarin poisoning, but fails to protect against VX or parathion. Survival and attenuation of clinical signs in tabun- or sarin-poisoned animals are associated with a

  16. Deletion of the GluA1 AMPA Receptor Subunit Alters the Expression of Short-Term Memory

    ERIC Educational Resources Information Center

    Sanderson, David J.; Sprengel, Rolf; Seeburg, Peter H.; Bannerman, David M.

    2011-01-01

    Deletion of the GluA1 AMPA receptor subunit selectively impairs short-term memory for spatial locations. We further investigated this deficit by examining memory for discrete nonspatial visual stimuli in an operant chamber. Unconditioned suppression of magazine responding to visual stimuli was measured in wild-type and GluA1 knockout mice.…

  17. [Influence of activation and blockade of NMDA receptors on extinction of passive avoidance response in mice with different levels of anxiety].

    PubMed

    Tomilenko, R A; Dubrovina, N I

    2006-03-01

    Influence of agonist (D-cycloserine) and antagonist (dizocilpine) N-methyl-D-aspartate receptors on learning and extinction of passive avoidance response in medium-, high-, and low-anxious mice was studied. In medium-anxious mice, D-cycloserine (30 mg/kg) although not changing learning accelerated development of extinction, whereas dizocilpine (0.15 mg/kg), while impairing passive avoidance learning, detained the extinction. In high-anxious mice with good retrieval of memory trace and absence of extinction, D-cycloserine was ineffective, whereas dizocilpine reduced learning and promoted retention of memory trace retrieval at the generated level on extinction. In low-anxious mice, D-cycloserine impaired learning and accelerated extinction, whereas dizocilpine completely blocked learning and retention of passive avoidance response.

  18. Effects of activation and blockade of NMDA receptors on the extinction of a conditioned passive avoidance response in mice with different levels of anxiety.

    PubMed

    Tomilenko, R A; Dubrovina, N I

    2007-06-01

    The effects of an agonist (D-cycloserine) and an antagonist (dizocilpine) of N-methyl-D-aspartate (NMDA) receptors on the learning and extinction of a conditioned passive avoidance response were studied in mice with low, intermediate, and high levels of anxiety. In intermediate-anxiety mice, D-cycloserine (30 mg/kg) had no effect on learning but accelerated extinction, while dizocilpine (0.15 mg/kg) degraded acquisition of the reflex but delayed extinction. In high-anxiety mice, with good learning and no extinction, D-cycloserine had no effect, while dizocilpine decreased learning and facilitated retention of performance of the memory trace at the ongoing level in conditions promoting extinction. In low-anxiety mice, D-cycloserine degraded learning and accelerated extinction, while dizocilpine completely blocked learning and the retention of the passive avoidance response.

  19. (I) Pharmacological profiling of a novel modulator of the α7 nicotinic receptor: Blockade of a toxic acetylcholinesterase-derived peptide increased in Alzheimer brains.

    PubMed

    Garcia-Ratés, Sara; Morrill, Paul; Tu, Henry; Pottiez, Gwenael; Badin, Antoine-Scott; Tormo-Garcia, Cristina; Heffner, Catherine; Coen, Clive W; Greenfield, Susan A

    2016-06-01

    The primary cause of Alzheimer's disease is unlikely to be the much studied markers amyloid beta or tau. Their widespread distribution throughout the brain does not account for the specific identity and deep subcortical location of the primarily vulnerable neurons. Moreover an unusual and intriguing feature of these neurons is that, despite their diverse transmitters, they all contain acetylcholinesterase. Here we show for the first time that (1) a peptide derived from acetylcholinesterase, with independent trophic functions that turn toxic in maturity, is significantly raised in the Alzheimer midbrain and cerebrospinal fluid; (2) a synthetic version of this peptide enhances calcium influx and eventual production of amyloid beta and tau phosphorylation via an allosteric site on the α7 nicotinic receptor; (3) a synthetic cyclic version of this peptide is neuroprotective against the toxicity not only of its linear counterpart but also of amyloid beta, thereby opening up the prospect of a novel therapeutic approach. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. 5-HT2 receptor blockade exhibits 5-HT vasodilator effects via nitric oxide, prostacyclin and ATP-sensitive potassium channels in rat renal vasculature.

    PubMed

    García-Pedraza, J A; García, M; Martín, M L; Rodríguez-Barbero, A; Morán, A

    2016-04-01

    The aim of this study was to determine whether orally sarpogrelate (selective 5-HT2 antagonist) treatment (30 mg/kg/day; 14 days) could modify 5-HT renal vasoconstrictor responses, characterizing 5-HT receptors and mediator mechanisms involved in serotonergic responses in the in situ autoperfused rat kidney. Intra-arterial (i.a.) injections of 5-HT (0.00000125 to 0.1 μg/kg) decreased renal perfusion pressure (RPP) but did not affect the mean blood pressure (MBP). i.a. agonists 5-CT (5-HT1/7), CGS-12066B (5-HT1B), L-694,247 (5-HT1D) or AS-19 (5-HT7) mimicked renal 5-HT vasodilator effect. However, neither 8-OH-DPAT (5-HT1A) nor 1-phenylbiguanide (5-HT3) modified RPP. Moreover: (i) GR-55562 (5-HT1B antagonist) and L-NAME (nitric oxide synthase [NOS] inhibitor) blocked CGS-12066B-induced vasodilator response, (ii) LY310762 (5-HT1D antagonist) and indomethacin (non-selective cyclooxygenase inhibitor) blocked L-694,247-induced vasodilator response; (iii) SB-258719 (5-HT7 antagonist) and glibenclamide (ATP-sensitive K+ channel blocker) blocked AS-19-induced vasodilator response; and (iv) 5-HT- or 5-CT-elicited renal vasodilation was significantly blocked by the mixture of GR-55562 + LY310762 + SB-258719. Furthermore, eNOS and iNOS proteins and prostacyclin levels are overexpressed in sarpogrelate-treated rats. Our data suggest that 5-HT exerts renal vasodilator effect in the in situ autoperfused sarpogrelate-treated rat kidney, mediated by 5-HT1D, 5-HT1B and 5-HT7 receptors, involving cyclooxygenase-derived prostacyclin, nitric oxide synthesis/release and ATP-sensitive K+ channels, respectively.

  1. The second Lilly Prize Lecture, University of Newcastle, July 1977. beta-Adrenergic receptor blockade in hypertension, past, present and future.

    PubMed Central

    Prichard, B N

    1978-01-01

    All beta-adrenoceptor blocking drugs that have been described share the common property of being competitive inhibitors. They differ in their associated properties, the presence or absence of cardioselectivity, membrane stabilizing activity, and partial agonist activity. Recently some beta-adrenoceptor blocking drugs have been reported which also possess alpha-adrenoceptor blocking activity. The associated properties have been used as a basis for classifying beta-adrenoceptor blocking drugs (Fitzgerald, 1969, 1972). The presence or absence of cardioselectivity is most useful for dividing beta-adrenoceptor blocking drugs. The non-selective drugs (Division I) can be further divided according to the presence or absence of intrinsic sympathomimetic activity (ISA) and membrane stabilizing activity (Fitzgerald's groups I-IV). Group I possess both membrane activity and ISA, e.g. alprenolol, oxprenolol, group II just membrane action, e.g. propanolol, group III ISA but no membrane action, e.g. pindolol. Fitzgerald placed pindolol in group I but should be placed in group III as it possesses a high degree of beta-adrenoceptor blocking potency in relation to its membrane activity (Prichard, 1974). Finally drugs in group IV have neither ISA nor membrane action, e.g. sotalol, timolol. The cardioselective drugs (Division II) can be similarly sub-divided into groups I-IV according to the presence or absence of ISA or membrane action (Fitzgerald grouped all these together as group V). Lastly there are new beta-adrenergic receptor blocking drugs which in addition have alpha- adrenergic receptor blocking properties (Division III). PMID:26370

  2. Targeting tumour re-wiring by triple blockade of mTORC1, epidermal growth factor, and oestrogen receptor signalling pathways in endocrine-resistant breast cancer.

    PubMed

    Ribas, Ricardo; Pancholi, Sunil; Rani, Aradhana; Schuster, Eugene; Guest, Stephanie K; Nikitorowicz-Buniak, Joanna; Simigdala, Nikiana; Thornhill, Allan; Avogadri-Connors, Francesca; Cutler, Richard E; Lalani, Alshad S; Dowsett, Mitch; Johnston, Stephen R; Martin, Lesley-Ann

    2018-06-08

    Endocrine therapies are the mainstay of treatment for oestrogen receptor (ER)-positive (ER + ) breast cancer (BC). However, resistance remains problematic largely due to enhanced cross-talk between ER and growth factor pathways, circumventing the need for steroid hormones. Previously, we reported the anti-proliferative effect of everolimus (RAD001-mTORC1 inhibitor) with endocrine therapy in resistance models; however, potential routes of escape from treatment via ERBB2/3 signalling were observed. We hypothesised that combined targeting of three cellular nodes (ER, ERBB, and mTORC1) may provide enhanced long-term clinical utility. A panel of ER + BC cell lines adapted to long-term oestrogen deprivation (LTED) and expressing ESR1 wt or ESR1 Y537S , modelling acquired resistance to an aromatase-inhibitor (AI), were treated in vitro with a combination of RAD001 and neratinib (pan-ERBB inhibitor) in the presence or absence of oestradiol (E2), tamoxifen (4-OHT), or fulvestrant (ICI182780). End points included proliferation, cell signalling, cell cycle, and effect on ER-mediated transactivation. An in-vivo model of AI resistance was treated with monotherapies and combinations to assess the efficacy in delaying tumour progression. RNA-seq analysis was performed to identify changes in global gene expression as a result of the indicated therapies. Here, we show RAD001 and neratinib (pan-ERBB inhibitor) caused a concentration-dependent decrease in proliferation, irrespective of the ESR1 mutation status. The combination of either agent with endocrine therapy further reduced proliferation but the maximum effect was observed with a triple combination of RAD001, neratinib, and endocrine therapy. In the absence of oestrogen, RAD001 caused a reduction in ER-mediated transcription in the majority of the cell lines, which associated with a decrease in recruitment of ER to an oestrogen-response element on the TFF1 promoter. Contrastingly, neratinib increased both ER

  3. Androgen receptor antagonism drives cytochrome P450 17A1 inhibitor efficacy in prostate cancer

    PubMed Central

    Norris, John D.; Ellison, Stephanie J.; Baker, Jennifer G.; Stagg, David B.; Wardell, Suzanne E.; Park, Sunghee; Alley, Holly M.; Baldi, Robert M.; Yllanes, Alexander; Andreano, Kaitlyn J.; Stice, James P.; Lawrence, Scott A.; Eisner, Joel R.; Price, Douglas K.; Moore, William R.; Figg, William D.; McDonnell, Donald P.

    2017-01-01

    The clinical utility of inhibiting cytochrome P450 17A1 (CYP17), a cytochrome p450 enzyme that is required for the production of androgens, has been exemplified by the approval of abiraterone for the treatment of castration-resistant prostate cancer (CRPC). Recently, however, it has been reported that CYP17 inhibitors can interact directly with the androgen receptor (AR). A phase I study recently reported that seviteronel, a CYP17 lyase–selective inhibitor, ædemonstrated a sustained reduction in prostate-specific antigen in a patient with CRPC, and another study showed seviteronel’s direct effects on AR function. This suggested that seviteronel may have therapeutically relevant activities in addition to its ability to inhibit androgen production. Here, we have demonstrated that CYP17 inhibitors, with the exception of orteronel, can function as competitive AR antagonists. Conformational profiling revealed that the CYP17 inhibitor–bound AR adopted a conformation that resembled the unliganded AR (apo-AR), precluding nuclear localization and DNA binding. Further, we observed that seviteronel and abiraterone inhibited the growth of tumor xenografts expressing the clinically relevant mutation AR-F876L and that this activity could be attributed entirely to competitive AR antagonism. The results of this study suggest that the ability of CYP17 inhibitors to directly antagonize the AR may contribute to their clinical efficacy in CRPC. PMID:28463227

  4. [Influence of stimulation and blockade of α4β2 nicotinic acetylcholine receptors on learning of female rats in basic phases of ovary cycle].

    PubMed

    Fedotova, Iu O

    2014-03-01

    The present work was devoted to the comparative analysis of α4β2 nicotinic acetylcholine receptors (nAChRs) in learning/memory processes during ovary cycle in the adult female rats. RJR-2403 (1.0 mg/kg, i. p.), α4β2 nAChRs agonist and mecamylamine (1.0 mg/kg, i. p.), α4β2 nAChRs antagonist were injected chronically during 14 days. The processes of learning/memory were assessed in different models of learning: passive avoidance performance and Morris water maze. Chronic RJR-2403 administration to females improved the passive avoidance performance in proestrous and estrous as compared to the control animals. Also, RJR-2403 restored spatial learning of rats during proestrous phases in Morris water maze, and stimulated the dynamics of spatial learning during estrous phases. On the contrary, the chronic mecamylamine administration impaired non-spatial, and especially, spatial learning in females during key phases of ovary cycle. The results of the study suggest positive effect of α4β2 nAChRs stimulation in learning/memory processes during ovary cycle in the adult female rats.

  5. The Role of cGMP on Adenosine A1 Receptor-mediated Inhibition of Synaptic Transmission at the Hippocampus

    PubMed Central

    Pinto, Isa; Serpa, André; Sebastião, Ana M.; Cascalheira, José F.

    2016-01-01

    Both adenosine A1 receptor and cGMP inhibit synaptic transmission at the hippocampus and recently it was found that A1 receptor increased cGMP levels in hippocampus, but the role of cGMP on A1 receptor-mediated inhibition of synaptic transmission remains to be established. In the present work we investigated if blocking the NOS/sGC/cGMP/PKG pathway using nitric oxide synthase (NOS), protein kinase G (PKG), and soluble guanylyl cyclase (sGC) inhibitors modify the A1 receptor effect on synaptic transmission. Neurotransmission was evaluated by measuring the slope of field excitatory postsynaptic potentials (fEPSPs) evoked by electrical stimulation at hippocampal slices. N6-cyclopentyladenosine (CPA, 15 nM), a selective A1 receptor agonist, reversibly decreased the fEPSPs by 54 ± 5%. Incubation of the slices with an inhibitor of NOS (L-NAME, 200 μM) decreased the CPA effect on fEPSPs by 57 ± 9% in female rats. In males, ODQ (10 μM), an sGC inhibitor, decreased the CPA inhibitory effect on fEPSPs by 23 ± 6%, but only when adenosine deaminase (ADA,1 U/ml) was present; similar results were found in females, where ODQ decreased CPA-induced inhibition of fEPSP slope by 23 ± 7%. In male rats, the presence of the PKG inhibitor (KT5823, 1 nM) decreased the CPA effect by 45.0 ± 9%; similar results were obtained in females, where KT5823 caused a 32 ± 9% decrease on the CPA effect. In conclusion, the results suggest that the inhibitory action of adenosine A1 receptors on synaptic transmission at hippocampus is, in part, mediated by the NOS/sGC/cGMP/PKG pathway. PMID:27148059

  6. Blockade of epidermal growth factor receptor signaling in tumor cells and tumor-associated endothelial cells for therapy of androgen-independent human prostate cancer growing in the bone of nude mice.

    PubMed

    Kim, Sun-Jin; Uehara, Hisanori; Karashima, Takashi; Shepherd, David L; Killion, Jerald J; Fidler, Isaiah J

    2003-03-01

    We determined whether blockade of the epidermal growth factor receptor (EGF-R) signaling pathway by oral administration of the EGF-R tyrosine kinase inhibitor (PKI 166) alone or in combination with injectable Taxol inhibits the growth of PC-3MM2 human prostate cancer cells in the bone of nude mice. Male nude mice implanted with PC-3MM2 cells in the tibia were treated with oral administrations of PKI 166 or PKI 166 plus injectable Taxol beginning 3 days after implantation. The incidence and size of bone tumors and destruction of bone were determined by digitalized radiography. Expression of epidermal growth factor (EGF), EGF-R, and activated EGF-R in tumor cells and tumor-associated endothelial cells was determined by immunohistochemistry. Oral administration of PKI 166 or PKI 166 plus injectable Taxol reduced the incidence and size of bone tumors and destruction of bone. Immunohistochemical analysis revealed that PC-3MM2 cells growing adjacent to the bone expressed high levels of EGF and activated EGF-R, whereas tumor cells in the adjacent musculature did not. Moreover, endothelial cells within the bone tumor lesions, but not in uninvolved bone or tumors in the muscle, expressed high levels of activated EGF-R. Treatment with PKI 166 and more so with PKI 166 plus Taxol significantly inhibited phosphorylation of EGF-R on tumor and endothelial cells and induced significant apoptosis and endothelial cells within tumor lesions. These data indicate that endothelial cells exposed to EGF produced by tumor cells express activated EGF-R and that targeting EGF-R can produce significant therapeutic effects against prostate cancer bone metastasis.

  7. Blockade of the High-Affinity Interleukin-2 Receptors with Daclizumab High-Yield Process: Pharmacokinetic/Pharmacodynamic Analysis of Single- and Multiple-Dose Phase I Trials.

    PubMed

    Minocha, Mukul; Tran, Jonathan Q; Sheridan, James P; Othman, Ahmed A

    2016-01-01

    Daclizumab high-yield process (DAC HYP) is a humanized monoclonal antibody that selectively blocks the α-subunit (CD25) of the high-affinity interleukin-2 receptors, and has shown robust efficacy as a treatment for multiple sclerosis (MS). This work quantitatively characterized the relationship between DAC HYP serum concentrations and saturation of CD25 expressed on antigen-rich target T cells in blood. Serial pharmacokinetic and 968 CD25 measurements from three double-blind, randomized, placebo-controlled, phase I studies of DAC HYP (50-300 mg subcutaneous and 200-400 mg intravenous doses or placebo) in healthy volunteers (n = 95) were analyzed using nonlinear mixed-effects modeling. CD25 occupancy was determined using flow cytometry and a fluorescently-labeled DAC HYP-competing antibody. CD25 occupancy was described using a direct inhibitory sigmoidal maximum effect (E max) model (where DAC HYP fully inhibited CD25 labeling with competing antibody). Two IC50 (serum concentration corresponding to 50 % of maximal inhibition) parameters were used to describe rapid CD25 saturation at initiation of dosing and apparently slower desaturation during DAC HYP washout. Parameter estimates (95 % bootstrap confidence intervals) were: baseline CD25 labeling, 47 % (45-48); DAC HYP IC50(saturation), 0.023 µg/mL (0.005-0.073); IC50(desaturation) 0.86 µg/mL (0.74-0.98); Hill coefficient 5.6 (4.3-6.8). Based on the developed model, the 150 mg monthly subcutaneous regimen of DAC HYP in subjects with MS is predicted to saturate CD25 on target effector T cells within a few hours of dosing and maintain CD25 saturation during the entire dosing interval. Free CD25 levels return to baseline within 4-6 months of the last DAC HYP dose.

  8. Blockade of AT1 Receptors Protects the Blood–Brain Barrier and Improves Cognition in Dahl Salt-Sensitive Hypertensive Rats

    PubMed Central

    Pelisch, Nicolas; Hosomi, Naohisa; Ueno, Masaki; Nakano, Daisuke; Hitomi, Hirofumi; Mogi, Masaki; Shimada, Kenji; Kobori, Hiroyuki; Horiuchi, Masatsugu; Sakamoto, Haruhiko; Matsumoto, Masayasu; Kohno, Masakazu; Nishiyama, Akira

    2011-01-01

    BACKGROUND The present study tested the hypothesis that inappropriate activation of the brain renin–angiotensin system (RAS) contributes to the pathogenesis of blood–brain barrier (BBB) disruption and cognitive impairment during development of salt-dependent hypertension. Effects of an angiotensin II (AngII) type-1 receptor blocker (ARB), at a dose that did not reduce blood pressure, were also examined. METHODS Dahl salt-sensitive (DSS) rats at 6 weeks of age were assigned to three groups: low-salt diet (DSS/L; 0.3% NaCl), high-salt diet (DSS/H; 8% NaCl), and high-salt diet treated with ARB, olmesartan at 1 mg/kg. RESULTS DSS/H rats exhibited hypertension, leakage from brain microvessels in the hippocampus, and impaired cognitive functions, which were associated with increased brain AngII levels, as well as decreased mRNA levels of tight junctions (TJs) and collagen-IV in the hippocampus. In DSS/H rats, olmesartan treatment, at a dose that did not alter blood pressure, restored the cognitive decline, and ameliorated leakage from brain microvessels. Olmesartan also decreased brain AngII levels and restored mRNA expression of TJs and collagen-IV in DSS/H rats. CONCLUSIONS These results suggest that during development of salt-dependent hypertension, activation of the brain RAS contributes to BBB disruption and cognitive impairment. Treatment with an ARB could elicit neuroprotective effects in cognitive disorders by preventing BBB permeability, which is independent of blood pressure changes. PMID:21164491

  9. Dopamine receptor blockade attenuates the general incentive motivational effects of noncontingently delivered rewards and reward-paired cues without affecting their ability to bias action selection.

    PubMed

    Ostlund, Sean B; Maidment, Nigel T

    2012-01-01

    Environmental cues affect our behavior in a variety of ways. Despite playing an invaluable role in guiding our daily activities, such cues also appear to trigger the harmful, compulsive behaviors that characterize addiction and other disorders of behavioral control. In instrumental conditioning, rewards and reward-paired cues bias action selection and invigorate reward-seeking behaviors, and appear to do so through distinct neurobehavioral processes. Although reward-paired cues are known to invigorate performance through a dopamine-dependent incentive motivational process, it is not known if dopamine also mediates the influence of rewards and reward-paired cues over action selection. The current study contrasted the effects of systemic administration of the nonspecific dopamine receptor antagonist flupentixol on response invigoration and action bias in Pavlovian-instrumental transfer, a test of cue-elicited responding, and in instrumental reinstatement, a test of noncontingent reward-elicited responding. Hungry rats were trained on two different stimulus-outcome relationships (eg, tone-grain pellets and noise-sucrose solution) and two different action-outcome relationships (eg, left press-grain and right press-sucrose). At test, we found that flupentixol pretreatment blocked the response invigoration generated by the cues but spared their ability to bias action selection to favor the action whose outcome was signaled by the cue being presented. The response-biasing influence of noncontingent reward deliveries was also unaffected by flupentixol. Interestingly, although flupentixol had a modest effect on the immediate response invigoration produced by those rewards, it was particularly potent in countering the lingering enhancement of responding produced by multiple reward deliveries. These findings indicate that dopamine mediates the general incentive motivational effects of noncontingent rewards and reward-paired cues but does not support their ability to bias

  10. Clozapine blockade of MK-801-induced learning/memory impairment in the mEPM: Role of 5-HT1A receptors and hippocampal BDNF levels.

    PubMed

    López Hill, Ximena; Richeri, Analía; Scorza, María Cecilia

    2017-10-01

    Cognitive impairment associated with schizophrenia (CIAS) is highly prevalent and affects the overall functioning of patients. Clozapine (Clz), an atypical antipsychotic drug, significantly improves CIAS although the underlying mechanisms remain under study. The role of the 5-HT 1A receptor (5-HT 1A -R) in the ability of Clz to prevent the learning/memory impairment induced by MK-801 was investigated using the modified elevated plus-maze (mEPM) considering the Transfer latency (TL) as an index of spatial memory. We also investigated if changes in hippocampal brain-derived neurotrophic factor (BDNF) levels underlie the behavioral prevention induced by Clz. Clz (0.5 and 1mg/kg)- or vehicle-pretreated Wistar rats were injected with MK-801 (0.05mg/kg) or saline. TL was evaluated 35min later (TL1, acquisition session) while learning/memory performance was measured 24h (TL2, retention session) and 48h later (TL3, long-lasting effect). WAY-100635, a 5-HT 1A -R antagonist, was pre-injected (0.3mg/kg) to examine the presumed 5-HT 1A -R involvement in Clz action. At TL2, another experimental group treated with Clz and MK-801 and its respective control groups were added to measure BDNF protein levels by ELISA. TL1 and TL3 were not significantly modified by the different treatments. MK-801 increased TL2 compared to control group leading a disruption of spatial memory processing which was markedly attenuated by Clz. WAY-100635 suppressed this action supporting a relevant role of 5-HT 1A -R in the Clz mechanism of action to improve spatial memory dysfunction. Although a significant decrease of hippocampal BDNF levels underlies the learning/memory impairment induced by MK-801, this effect was not significantly prevented by Clz. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Alterations in interhemispheric gamma-band connectivity are related to the emergence of auditory verbal hallucinations in healthy subjects during NMDA-receptor blockade.

    PubMed

    Thiebes, Stephanie; Steinmann, Saskia; Curic, Stjepan; Polomac, Nenad; Andreou, Christina; Eichler, Iris-Carola; Eichler, Lars; Zöllner, Christian; Gallinat, Jürgen; Leicht, Gregor; Mulert, Christoph

    2018-06-01

    Auditory verbal hallucinations (AVH) are a common positive symptom of schizophrenia. Excitatory-to-inhibitory (E/I) imbalance related to disturbed N-methyl-D-aspartate receptor (NMDAR) functioning has been suggested as a possible mechanism underlying altered connectivity and AVH in schizophrenia. The current study examined the effects of ketamine, a NMDAR antagonist, on glutamate-related mechanisms underlying interhemispheric gamma-band connectivity, conscious auditory perception during dichotic listening (DL), and the emergence of auditory verbal distortions and hallucinations (AVD/AVH) in healthy volunteers. In a single-blind, pseudo-randomized, placebo-controlled crossover design, nineteen male, right-handed volunteers were measured using 64 channel electroencephalography (EEG). Psychopathology was assessed with the PANSS interview and the 5D-ASC questionnaire, including a subscale to detect auditory alterations with regard to AVD/AVH (AUA-AVD/AVH). Interhemispheric connectivity analysis was performed using eLORETA source estimation and lagged phase synchronization (LPS) in the gamma-band range (30-100 Hz). Ketamine induced positive symptoms such as hallucinations in a subgroup of healthy subjects. In addition, interhemispheric gamma-band connectivity was found to be altered under ketamine compared to placebo, and subjects with AUA-AVD/AVH under ketamine showed significantly higher interhemispheric gamma-band connectivity than subjects without AUA-AVD/AVH. These findings demonstrate a relationship between NMDAR functioning, interhemispheric connectivity in the gamma-band frequency range between bilateral auditory cortices and the emergence of AVD/AVH in healthy subjects. The result is in accordance with the interhemispheric miscommunication hypothesis of AVH and argues for a possible role of glutamate in AVH in schizophrenia.

  12. Role of beta-adrenergic receptor gene polymorphisms in the long-term effects of beta-blockade with carvedilol in patients with chronic heart failure.

    PubMed

    Metra, Marco; Covolo, Loredana; Pezzali, Natalia; Zacà, Valerio; Bugatti, Silvia; Lombardi, Carlo; Bettari, Luca; Romeo, Alessia; Gelatti, Umberto; Giubbini, Raffaele; Donato, Francesco; Dei Cas, Livio

    2010-02-01

    Beta-blockers are mainstay of current treatment of heart failure (HF). Beta-adrenergic receptors (AR) single nucleotide gene polymorphisms (SNPs) may influence the sensitivity and density of beta-AR. We assessed the relation between three common beta-AR SNPs and the response to carvedilol administration. We studied 183 consecutive patients with chronic HF due to ischemic or nonischemic cardiomyopathy, a LV ejection fraction (LVEF) < or = 0.35, not previously treated with beta-blockers. Each patient underwent gated-SPECT radionuclide ventriculography, cardiopulmonary exercise testing and invasive hemodynamic monitoring at baseline and after 12 months of carvedilol administration at maintenance dosages. The beta1-AR gene Arg389Gly and the beta2-AR gene Arg16Gly SNPs were not related to the response to carvedilol administration. Homozygotes for the Glu27Glu allele showed a greater increase in the LVEF, compared to the other patients (+13.0 +/- 12.2% versus +7.1 +/- 8.1% in the Gln27Gln homozygotes, and 8.3 +/- 11.4% units in the Gln27Glu heterozygotes; p = 0.022 by ANOVA). Glu27Glu homozygotes also showed a greater decline in the pulmonary wedge pressure both at rest and at peak exercise. Gln27Glu SNP was selected amongst the determinants of the LVEF response to carvedilol at multivariable analysis, in addition to the cause of cardiomyopathy, baseline systolic blood pressure and the dose of carvedilol administered. Beta1-AR Arg389Gly and beta2-AR Arg16Gly SNPs are not related to the response to carvedilol therapy. In contrast, the Gln27Glu SNP is a determinant of the LVEF response to this agent in patients with chronic HF.

  13. Hypothermia in mouse is caused by adenosine A1 and A3 receptor agonists and AMP via three distinct mechanisms.

    PubMed

    Carlin, Jesse Lea; Jain, Shalini; Gizewski, Elizabeth; Wan, Tina C; Tosh, Dilip K; Xiao, Cuiying; Auchampach, John A; Jacobson, Kenneth A; Gavrilova, Oksana; Reitman, Marc L

    2017-03-01

    Small mammals have the ability to enter torpor, a hypothermic, hypometabolic state, allowing impressive energy conservation. Administration of adenosine or adenosine 5'-monophosphate (AMP) can trigger a hypothermic, torpor-like state. We investigated the mechanisms for hypothermia using telemetric monitoring of body temperature in wild type and receptor knock out (Adora1 -/- , Adora3 -/- ) mice. Confirming prior data, stimulation of the A 3 adenosine receptor (AR) induced hypothermia via peripheral mast cell degranulation, histamine release, and activation of central histamine H 1 receptors. In contrast, A 1 AR agonists and AMP both acted centrally to cause hypothermia. Commonly used, selective A 1 AR agonists, including N 6 -cyclopentyladenosine (CPA), N 6 -cyclohexyladenosine (CHA), and MRS5474, caused hypothermia via both A 1 AR and A 3 AR when given intraperitoneally. Intracerebroventricular dosing, low peripheral doses of Cl-ENBA [(±)-5'-chloro-5'-deoxy-N 6 -endo-norbornyladenosine], or using Adora3 -/- mice allowed selective stimulation of A 1 AR. AMP-stimulated hypothermia can occur independently of A 1 AR, A 3 AR, and mast cells. A 1 AR and A 3 AR agonists and AMP cause regulated hypothermia that was characterized by a drop in total energy expenditure, physical inactivity, and preference for cooler environmental temperatures, indicating a reduced body temperature set point. Neither A 1 AR nor A 3 AR was required for fasting-induced torpor. A 1 AR and A 3 AR agonists and AMP trigger regulated hypothermia via three distinct mechanisms. Published by Elsevier Ltd.

  14. Myostatin deficiency but not anti-myostatin blockade induces marked proteomic changes in mouse skeletal muscle.

    PubMed

    Salzler, Robert R; Shah, Darshit; Doré, Anthony; Bauerlein, Roy; Miloscio, Lawrence; Latres, Esther; Papadopoulos, Nicholas J; Olson, William C; MacDonald, Douglas; Duan, Xunbao

    2016-07-01

    Pharmacologic blockade of the myostatin (Mstn)/activin receptor pathway is being pursued as a potential therapy for several muscle wasting disorders. The functional benefits of blocking this pathway are under investigation, in particular given the findings that greater muscle hypertrophy results from Mstn deficiency arising from genetic ablation compared to post-developmental Mstn blockade. Using high-resolution MS coupled with SILAC mouse technology, we quantitated the relative proteomic changes in gastrocnemius muscle from Mstn knockout (Mstn(-/-) ) and mice treated for 2-weeks with REGN1033, an anti-Mstn antibody. Relative to wild-type animals, Mstn(-/-) mice had a two-fold greater muscle mass and a >1.5-fold change in expression of 12.0% of 1137 quantified muscle proteins. In contrast, mice treated with REGN1033 had minimal changes in muscle proteome (0.7% of 1510 proteins >1.5-fold change, similar to biological difference 0.5% of 1310) even though the treatment induced significant 20% muscle mass increase. Functional annotation of the altered proteins in Mstn(-/-) mice corroborates the mutiple physiological changes including slow-to-fast fiber type switch. Thus, the proteome-wide protein expression differs between Mstn(-/-) mice and mice subjected to specific Mstn blockade post-developmentally, providing molecular-level insights to inform mechanistic hypotheses to explain the observed functional differences. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Adenosine A1 receptors modulate high voltage-activated Ca2+ currents and motor pattern generation in the Xenopus embryo

    PubMed Central

    Brown, Paul; Dale, Nicholas

    2000-01-01

    Adenosine causes voltage- and non-voltage-dependent inhibition of high voltage-activated (HVA) Ca2+ currents in Xenopus laevis embryo spinal neurons. As this inhibition can be blocked by 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and mimicked by N6-cyclopentyladenosine (CPA) it appears to be mediated by A1 receptors. Agents active at A2 receptors either were without effect or could be blocked by DPCPX. AMP had no agonist action on these receptors. By using ω-conotoxin GVIA we found that adenosine inhibited an N-type Ca2+ current as well as a further unidentified HVA current that was insensitive to dihydropyridines, ω-agatoxin TK and ω-conotoxin MVIIC. Both types of current were subject to voltage- and non-voltage-dependent inhibition. We used CPA and DPCPX to test whether A1 receptors regulated spinal motor pattern generation in spinalized Xenopus embryos. DPCPX caused a near doubling of, while CPA greatly shortened, the length of swimming episodes. In addition, DPCPX slowed, while CPA greatly speeded up, the rate of run-down of motor activity. Our results demonstrate a novel action of A1 receptors in modulating spinal motor activity. Furthermore they confirm that adenosine is produced continually throughout swimming episodes and acts to cause the eventual termination of activity. PMID:10856119

  16. Antidepressant-like effects induced by NMDA receptor blockade and NO synthesis inhibition in the ventral medial prefrontal cortex of rats exposed to the forced swim test.

    PubMed

    Pereira, Vitor Silva; Romano, Angélica; Wegener, Gregers; Joca, Sâmia R L

    2015-07-01

    Systemic treatment with NMDA receptor (NMDAR) antagonists, inhibitors of neuronal nitric oxide synthase (nNOS) or of soluble guanylyl cyclase (sGC), induce antidepressant-like effects in rats. Increased levels of glutamate and nitric oxide (NO) in the medial prefrontal cortex (MPFC) of stressed animals have been described in the literature. However, the role of the NMDAR-nNOS-sGC pathway of the MPFC in the mediation of forced swim-induced behaviors remains unclear. The aim of this work was to test the hypothesis that the inhibition of the NMDAR-nNOS-sGC pathway in the ventral MPFC (infralimbic (IL) or prelimbic (PL)) would elicit antidepressant-like effects in the forced swim test (FST). Rats implanted with cannulae aimed at the PL or the IL were exposed to the FST and injected with LY235959 (NMDAR antagonist), NPA (nNOS inhibitor), ODQ (sGC inhibitor), or carboxy-PTIO (NO scavenger). Additional groups received the AMPA antagonist, NBQX, before the effective doses of LY235959 or NPA. LY235959 administration into PL or IL before the FS pretest produced no effects. Administration of LY235959 (3 and 10 nmol/0.2 μL) after pretest was effective only when administered into the PL. However, the administration of NPA (0.01 nmol/0.2 μL), c-PTIO (1.0 nmol/0.2 μL), and ODQ (1.0 nmol/0.2 μL) into the PL or IL before the FST produced antidepressant-like effects. NBQX blocked the antidepressant-like effect of LY235959 but not of NPA. Blocking NMDAR or NO signaling in the vMPFC, either in the IL or the PL, induces antidepressant-like effects in the rat FST. These effects seemingly occur through independent mechanisms, since NBQX blocked the former effect but not the latter.

  17. Activation of the chemosensing transient receptor potential channel A1 (TRPA1) by alkylating agents.

    PubMed

    Stenger, Bernhard; Zehfuss, Franziska; Mückter, Harald; Schmidt, Annette; Balszuweit, Frank; Schäfer, Eva; Büch, Thomas; Gudermann, Thomas; Thiermann, Horst; Steinritz, Dirk

    2015-09-01

    The transient receptor potential ankyrin 1 (TRPA1) cation channel is expressed in different tissues including skin, lung and neuronal tissue. Recent reports identified TRPA1 as a sensor for noxious substances, implicating a functional role in the molecular toxicology. TRPA1 is activated by various potentially harmful electrophilic substances. The chemical warfare agent sulfur mustard (SM) is a highly reactive alkylating agent that binds to numerous biological targets. Although SM is known for almost 200 years, detailed knowledge about the pathophysiology resulting from exposure is lacking. A specific therapy is not available. In this study, we investigated whether the alkylating agent 2-chloroethyl-ethylsulfide (CEES, a model substance for SM-promoted effects) and SM are able to activate TRPA1 channels. CEES induced a marked increase in the intracellular calcium concentration ([Ca(2+)]i) in TRPA1-expressing but not in TRPA1-negative cells. The TRP-channel blocker AP18 diminished the CEES-induced calcium influx. HEK293 cells permanently expressing TRPA1 were more sensitive toward cytotoxic effects of CEES compared with wild-type cells. At low CEES concentrations, CEES-induced cytotoxicity was prevented by AP18. Proof-of-concept experiments using SM resulted in a pronounced increase in [Ca(2+)]i in HEK293-A1-E cells. Human A549 lung epithelial cells, which express TRPA1 endogenously, reacted with a transient calcium influx in response to CEES exposure. The CEES-dependent calcium response was diminished by AP18. In summary, our results demonstrate that alkylating agents are able to activate TRPA1. Inhibition of TRPA1 counteracted cellular toxicity and could thus represent a feasible approach to mitigate SM-induced cell damage.

  18. Traceable Coulomb blockade thermometry

    NASA Astrophysics Data System (ADS)

    Hahtela, O.; Mykkänen, E.; Kemppinen, A.; Meschke, M.; Prunnila, M.; Gunnarsson, D.; Roschier, L.; Penttilä, J.; Pekola, J.

    2017-02-01

    We present a measurement and analysis scheme for determining traceable thermodynamic temperature at cryogenic temperatures using Coulomb blockade thermometry. The uncertainty of the electrical measurement is improved by utilizing two sampling digital voltmeters instead of the traditional lock-in technique. The remaining uncertainty is dominated by that of the numerical analysis of the measurement data. Two analysis methods are demonstrated: numerical fitting of the full conductance curve and measuring the height of the conductance dip. The complete uncertainty analysis shows that using either analysis method the relative combined standard uncertainty (k  =  1) in determining the thermodynamic temperature in the temperature range from 20 mK to 200 mK is below 0.5%. In this temperature range, both analysis methods produced temperature estimates that deviated from 0.39% to 0.67% from the reference temperatures provided by a superconducting reference point device calibrated against the Provisional Low Temperature Scale of 2000.

  19. 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

  20. Class A1 scavenger receptor modulates glioma progression by regulating M2-like tumor-associated macrophage polarization

    PubMed Central

    Zhang, Hanwen; Zhang, Wenbin; Sun, Xuan; Dang, Ruoyu; Zhou, Rongmei; Bai, Hui; Ben, Jingjing; Zhu, Xudong; Zhang, Yan; Yang, Qing; Xu, Yong; Chen, Qi

    2016-01-01

    Macrophages enhance glioma development and progression by shaping the tumor microenvironment. Class A1 scavenger receptor (SR-A1), a pattern recognition receptor primarily expressed in macrophages, is up-regulated in many human solid tumors. We found that SR-A1 expression in 136 human gliomas was positively correlated with tumor grade (P<0.01), but not prognosis or tumor recurrence. SR-A1-expressing macrophages originated primarily from circulating monocytes attracted to tumor tissue, and were almost twice as numerous as resident microglia in glioma tissues (P<0.001). The effects of SR-A1 on glioma proliferation and invasion were assessed in vivo using an SR-A1-deficient murine orthotopic glioma model. SR-A1 deletion promoted M2-like tumor-associated macrophage (TAM) polarization in mice by activating STAT3 and STAT6, which resulted in robust orthotopic glioma proliferation and angiogenesis. Finally, we found that HSP70 might be an endogenous ligand that activates SR-A1-dependent anti-tumorigenic pathways in gliomas, although its expression does not appear informative for diagnostic purposes. Our findings demonstrate a relationship between TAMs, SR-A1 expression and glioma growth and provide new insights into the pathogenic role of TAMs in glioma. PMID:27367025

  1. Chronic hypoxia up-regulates expression of adenosine A1 receptors in DDT1-MF2 cells.

    PubMed

    Hammond, Lucy C; Bonnet, Claire; Kemp, Paul J; Yates, Michael S; Bowmer, Christopher J

    2004-02-01

    As the first step to understand how chronic hypoxia might regulate smooth muscle function in health and disease, we have employed an established immortalised cell model of smooth muscle, DDT1-MF2 cells, to address the hypothesis that adenosine A1 receptor density is modulated by O2 availability. Maximal specific binding (Bmax) of the selective adenosine A1 receptor antagonist, [3H]-DPCPX, to cell membranes increased 3.5-fold from 0.48 +/- 0.02 pmol/mg to 1.7 +/- 0.5 pmol/mg protein after 16 hr of hypoxia and this effect was not accompanied by any statistically significant changes in either binding affinity (0.84 +/- 0.2 nM vs. 1.2 +/- 0.3 nM) or Hill coefficient (1.1 +/- 0.1 vs. 0.99 +/- 0.03). Hypoxia-evoked increases in membrane receptor density were paralleled in intact DDT1-MF2 cells. In addition, the increase in [3H]-DPCPX binding to intact cells was inhibited by co-incubation during hypoxia with the translational inhibitor cycloheximide, the transcriptional blocker actinomycin D and the NFkappaB inhibitor sulphasalazine. Together, these data show that adenosine A1 receptor density is modulated, at least in part, by O2-dependent activation of the transcription factor NFkappaB and adds to the list of processes dynamically regulated by ambient oxygen availability. Since hypoxia is an initiating factor in acute renal failure, similar changes in transcription may account for up-regulation of adenosine A1 receptors noted previously in the renal vasculature of rats with acute renal failure.

  2. Effects of tianeptine on onset time of pentylenetetrazole-induced seizures in mice: possible role of adenosine A1 receptors.

    PubMed

    Uzbay, Tayfun I; Kayir, Hakan; Ceyhan, Mert

    2007-02-01

    Depression is a common psychiatric problem in epileptic patients. Thus, it is important that an antidepressant agent has anticonvulsant activity. This study was organized to investigate the effects of tianeptine, an atypical antidepressant, on pentylenetetrazole (PTZ)-induced seizure in mice. A possible contribution of adenosine receptors was also evaluated. Adult male Swiss-Webster mice (25-35 g) were subjects. PTZ (80 mg/kg, i.p.) was injected to mice 30 min after tianeptine (2.5-80 mg/kg, i.p.) or saline administration. The onset times of 'first myoclonic jerk' (FMJ) and 'generalized clonic seizures' (GCS) were recorded. Duration of 600 s was taken as a cutoff time in calculation of the onset time of the seizures. To evaluate the contribution of adenosine receptors in the effect of tianeptine, a nonspecific adenosine receptor antagonist caffeine, a specific A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a specific A2A receptor antagonist 8-(3-chlorostyryl) caffeine (CSC) or their vehicles were administered to the mice 15 min before tianeptine (80 mg/kg) or saline treatments. Tianeptine (40 and 80 mg/kg) pretreatment significantly delayed the onset time of FMJ and GCS. Caffeine (10-60 mg/kg, i.p.) dose-dependently blocked the retarding effect of tianeptine (80 mg/kg) on the onset times of FMJ and GCS. DPCPX (20 mg/kg) but not CSC (1-8 mg/kg) blocked the effect of tianeptine (80 mg/kg) on FMJ. Our results suggest that tianeptine delayed the onset time of PTZ-induced seizures via adenosine A1 receptors in mice. Thus, this drug may be a useful choice for epileptic patients with depression.

  3. Adenosine A1 Receptors in Mouse Pontine Reticular Formation Depress Breathing, Increase Anesthesia Recovery Time, and Decrease Acetylcholine Release

    PubMed Central

    Gettys, George C.; Liu, Fang; Kimlin, Ed; Baghdoyan, Helen A.; Lydic, Ralph

    2012-01-01

    Background Clinical and preclinical data demonstrate the analgesic actions of adenosine. Central administration of adenosine agonists, however, suppresses arousal and breathing by poorly understood mechanisms. This study tested the two-tailed hypothesis that adenosine A1 receptors in the pontine reticular formation (PRF) of C57BL/6J mice modulate breathing, behavioral arousal, and PRF acetylcholine release. Methods Three sets of experiments used 51 mice. First, breathing was measured by plethysmography after PRF microinjection of the adenosine A1 receptor agonist N6-sulfophenyl adenosine (SPA) or saline. Second, mice were anesthetized with isoflurane and time to recovery of righting response (RoRR) was quantified after PRF microinjection of SPA or saline. Third, acetylcholine release in the PRF was measured before and during microdialysis delivery of SPA, the adenosine A1 receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX), or SPA and DPCPX. Results First, SPA significantly decreased respiratory rate (−18%), tidal volume (−12%) and minute ventilation (−16%). Second, SPA concentration accounted for 76% of the variance in RoRR. Third, SPA concentration accounted for a significant amount of the variance in acetylcholine release (52%), RoRR (98%), and breathing rate (86%). DPCPX alone caused a concentration-dependent increase in acetylcholine, decrease in RoRR, and decrease in breathing rate. Coadministration of SPA and DPCPX blocked the SPA-induced decrease in acetylcholine and increase in RoRR. Conclusions Endogenous adenosine acting at adenosine A1 receptors in the PRF modulates breathing, behavioral arousal, and acetylcholine release. The results support the interpretation that an adenosinergic-cholinergic interaction within the PRF comprises one neurochemical mechanism underlying the wakefulness stimulus for breathing. PMID:23263018

  4. Adenosine A(1) receptors in mouse pontine reticular formation depress breathing, increase anesthesia recovery time, and decrease acetylcholine release.

    PubMed

    Gettys, George C; Liu, Fang; Kimlin, Ed; Baghdoyan, Helen A; Lydic, Ralph

    2013-02-01

    Clinical and preclinical data demonstrate the analgesic actions of adenosine. Central administration of adenosine agonists, however, suppresses arousal and breathing by poorly understood mechanisms. This study tested the two-tailed hypothesis that adenosine A1 receptors in the pontine reticular formation (PRF) of C57BL/6J mice modulate breathing, behavioral arousal, and PRF acetylcholine release. Three sets of experiments used 51 mice. First, breathing was measured by plethysmography after PRF microinjection of the adenosine A1 receptor agonist N-sulfophenyl adenosine (SPA) or saline. Second, mice were anesthetized with isoflurane and the time to recovery of righting response (RoRR) was quantified after a PRF microinjection of SPA or saline. Third, acetylcholine release in the PRF was measured before and during microdialysis delivery of SPA, the adenosine A1 receptor antagonist 1, 3-dipropyl-8-cyclopentylxanthine, or SPA and 1, 3-dipropyl-8-cyclopentylxanthine. First, SPA significantly decreased respiratory rate (-18%), tidal volume (-12%), and minute ventilation (-16%). Second, SPA concentration accounted for 76% of the variance in RoRR. Third, SPA concentration accounted for a significant amount of the variance in acetylcholine release (52%), RoRR (98%), and breathing rate (86%). 1, 3-dipropyl-8-cyclopentylxanthine alone caused a concentration-dependent increase in acetylcholine, a decrease in RoRR, and a decrease in breathing rate. Coadministration of SPA and 1, 3-dipropyl-8-cyclopentylxanthine blocked the SPA-induced decrease in acetylcholine and increase in RoRR. Endogenous adenosine acting at adenosine A1 receptors in the PRF modulates breathing, behavioral arousal, and acetylcholine release. The results support the interpretation that an adenosinergic-cholinergic interaction within the PRF comprises one neurochemical mechanism underlying the wakefulness stimulus for breathing.

  5. Role of A1 and A2A adenosine receptor agonists in adipose tissue inflammation induced by obesity in mice.

    PubMed

    DeOliveira, Caroline Candida; Paiva Caria, Cintia Rabelo E; Ferreira Gotardo, Erica Martins; Ribeiro, Marcelo Lima; Gambero, Alessandra

    2017-03-15

    Adenosine receptors are expressed in adipose tissue and control physiological and pathological events such as lipolysis and inflammation. The aim of this study was to evaluate the activity of N 6 -cyclopentyladenosine (CPA), a potent and selective A 1 adenosine receptor agonist; 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxyamidoadenosine hydrochloride (CGS-21680), an A 2A adenosine receptor agonist; and 5'-N-ethylcarboxamidoadenosine (NECA), a potent non-selective adenosine receptor agonist on adipose tissue inflammatory alterations induced by obesity in mice. Swiss mice were fed with a high-fat diet for 12 weeks and agonists were administered in the last two weeks. Body weight, adiposity and glucose homeostasis were evaluated. Inflammation in adipose tissue was assessed by evaluation of adipokine production and macrophage infiltration. Adenosine receptor signaling in adipose tissue was also evaluated. Mice that received CGS21680 presented an improvement in glucose homeostasis in association with systemically reduced inflammatory markers (TNF-α, PAI-1) and in the visceral adipose tissue (TNF-α, MCP-1, macrophage infiltration). Activation of p38 signaling was found in adipose tissue of this group of mice. NECA-treated mice presented some improvements in glucose homeostasis associated with an observed weight loss. Mice that received CPA presented only a reduction in the ex vivo basal lipolysis rate measured within visceral adipose tissue. In conclusion, administration of the A 2A receptor agonist to obese mice resulted in improvements in glucose homeostasis and adipose tissue inflammation, corroborating the idea that new therapeutics to treat obesity could emerge from these compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. 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.

  7. Adenosine-Induced Atrial Fibrillation: Localized Reentrant Drivers in Lateral Right Atria due to Heterogeneous Expression of Adenosine A1 Receptors and GIRK4 Subunits in the Human Heart.

    PubMed

    Li, Ning; Csepe, Thomas A; Hansen, Brian J; Sul, Lidiya V; Kalyanasundaram, Anuradha; Zakharkin, Stanislav O; Zhao, Jichao; Guha, Avirup; Van Wagoner, David R; Kilic, Ahmet; Mohler, Peter J; Janssen, Paul M L; Biesiadecki, Brandon J; Hummel, John D; Weiss, Raul; Fedorov, Vadim V

    2016-08-09

    Adenosine provokes atrial fibrillation (AF) with a higher activation frequency in right atria (RA) versus left atria (LA) in patients, but the underlying molecular and functional substrates are unclear. We tested the hypothesis that adenosine-induced AF is driven by localized reentry in RA areas with highest expression of adenosine A1 receptor and its downstream GIRK (G protein-coupled inwardly rectifying potassium channels) channels (IK,Ado). We applied biatrial optical mapping and immunoblot mapping of various atrial regions to reveal the mechanism of adenosine-induced AF in explanted failing and nonfailing human hearts (n=37). Optical mapping of coronary-perfused atria (n=24) revealed that adenosine perfusion (10-100 µmol/L) produced more significant shortening of action potential durations in RA (from 290±45 to 239±41 ms, 17.3±10.4%; P<0.01) than LA (from 307±24 to 286±23 ms, 6.7±6.6%; P<0.01). In 10 hearts, adenosine induced AF (317±116 s) that, when sustained (≥2 minutes), was primarily maintained by 1 to 2 localized reentrant drivers in lateral RA. Tertiapin (10-100 nmol/L), a selective GIRK channel blocker, counteracted adenosine-induced action potential duration shortening and prevented AF induction. Immunoblotting showed that the superior/middle lateral RA had significantly higher adenosine A1 receptor (2.7±1.7-fold; P<0.01) and GIRK4 (1.7±0.8-fold; P<0.05) protein expression than lateral/posterior LA. This study revealed a 3-fold RA-to-LA adenosine A1 receptor protein expression gradient in the human heart, leading to significantly greater RA versus LA repolarization sensitivity in response to adenosine. Sustained adenosine-induced AF is maintained by reentrant drivers localized in lateral RA regions with the highest adenosine A1 receptor/GIRK4 expression. Selective atrial GIRK channel blockade may effectively treat AF during conditions with increased endogenous adenosine. © 2016 American Heart Association, Inc.

  8. Ischaemic tolerance in aged mouse myocardium: the role of adenosine and effects of A1 adenosine receptor overexpression

    PubMed Central

    Headrick, John P; Willems, Laura; Ashton, Kevin J; Holmgren, Kirsten; Peart, Jason; Matherne, G Paul

    2003-01-01

    The genesis of the ischaemia intolerant phenotype in aged myocardium is poorly understood. We tested the hypothesis that impaired adenosine-mediated protection contributes to ischaemic intolerance, and examined whether this is countered by A1 adenosine receptor (A1AR) overexpression. Responses to 20 min ischaemia and 45 min reperfusion were assessed in perfused hearts from young (2–4 months) and moderately aged (16–18 months) mice. Post-ischaemic contractility was impaired by ageing with elevated ventricular diastolic (32 ± 2 vs. 18 ± 2 mmHg in young) and reduced developed (37 ± 3 vs. 83 ± 6 mmHg in young) pressures. Lactate dehydrogenase (LDH) loss was exaggerated (27 ± 2 vs. 16 ± 2 IU g−1in young) whereas the incidence of tachyarrhythmias was similar in young (15 ± 1 %) and aged hearts (16 ± 1 %). Functional analysis confirmed equipotent effects of 50 μm adenosine at A1 and A2 receptors in young and aged hearts. Nonetheless, while 50 μm adenosine improved diastolic (5 ± 1 mmHg) and developed pressures (134 ± 7 mmHg) and LDH loss (6 ± 2 IU g−1) in young hearts, it did not alter these variables in the aged group. Adenosine did attenuate arrhythmogenesis for both ages (to ∼10 %). In contrast to adenosine, 50 μm diazoxide reduced ischaemic damage and arrhythmogenesis for both ages. Contractile and anti-necrotic effects of adenosine were limited by 100 μm 5-hydroxydecanoate (5-HD) and 3 μm chelerythrine. Anti-arrhythmic effects were limited by 5-HD but not chelerythrine. Non-selective (100 μm 8-sulfophenyltheophylline) and A1-selective (150 nm 8-cyclopentyl-1,3-dipropylxanthine) adenosine receptor antagonism impaired ischaemic tolerance in young but not aged hearts. Quantitative real-time PCR and radioligand analysis indicated that impaired protection is unrelated to changes in A1AR mRNA transcription, or receptor density (∼8 fmol mg−1 protein in both age groups). However, A1AR overexpression improved tolerance for both ages, restoring

  9. A1 adenosine receptor attenuates intracerebral hemorrhage-induced secondary brain injury in rats by activating the P38-MAPKAP2-Hsp27 pathway.

    PubMed

    Zhai, Weiwei; Chen, Dongdong; Shen, Haitao; Chen, Zhouqing; Li, Haiying; Yu, Zhengquan; Chen, Gang

    2016-06-14

    This study was designed to determine the role of the A1 adenosine receptors in intracerebral hemorrhage (ICH)-induced secondary brain injury and the underlying mechanisms. A collagenase-induced ICH model was established in Sprague-Dawley rats, and cultured primary rat cortical neurons were exposed to oxyhemoglobin at a concentration of 10 μM to mimic ICH in vitro. The A1 adenosine receptor agonist N(6)-cyclohexyladenosine and antagonist 8-phenyl-1,3-dipropylxanthine were used to study the role of A1 adenosine receptor in ICH-induced secondary brain injury, and antagonists of P38 and Hsp27 were used to study the underlying mechanisms of A1 adenosine receptor actions. The protein level of A1 adenosine receptor was significantly increased by ICH, while there was no significant change in protein levels of the other 3 adenosine receptors. In addition, the A1 adenosine receptor expression could be increased by N(6)-cyclohexyladenosine and decreased by 8-phenyl-1,3-dipropylxanthine under ICH conditions. Activation of the A1 adenosine receptor attenuated neuronal apoptosis in the subcortex, which was associated with increased phosphorylation of P38, MAPK, MAPKAP2, and Hsp27. Inhibition of the A1 adenosine receptor resulted in opposite effects. Finally, the neuroprotective effect of the A1 adenosine receptor agonist N(6)-cyclohexyladenosine was inhibited by antagonists of P38 and Hsp27. This study demonstrates that activation of the A1 adenosine receptor by N(6)-cyclohexyladenosine could prevent ICH-induced secondary brain injury via the P38-MAPKAP2-Hsp27 pathway.

  10. Importance of GluA1 Subunit-Containing AMPA Glutamate Receptors for Morphine State-Dependency

    PubMed Central

    Aitta-aho, Teemu; Möykkynen, Tommi P.; Panhelainen, Anne E.; Vekovischeva, Olga Yu.; Bäckström, Pia; Korpi, Esa R.

    2012-01-01

    In state-dependency, information retrieval is most efficient when the animal is in the same state as it was during the information acquisition. State-dependency has been implicated in a variety of learning and memory processes, but its mechanisms remain to be resolved. Here, mice deficient in AMPA-type glutamate receptor GluA1 subunits were first conditioned to morphine (10 or 20 mg/kg s.c. during eight sessions over four days) using an unbiased procedure, followed by testing for conditioned place preference at morphine states that were the same as or different from the one the mice were conditioned to. In GluA1 wildtype littermate mice the same-state morphine dose produced the greatest expression of place preference, while in the knockout mice no place preference was then detected. Both wildtype and knockout mice expressed moderate morphine-induced place preference when not at the morphine state (saline treatment at the test); in this case, place preference was weaker than that in the same-state test in wildtype mice. No correlation between place preference scores and locomotor activity during testing was found. Additionally, as compared to the controls, the knockout mice showed unchanged sensitization to morphine, morphine drug discrimination and brain regional μ-opioid receptor signal transduction at the G-protein level. However, the knockout mice failed to show increased AMPA/NMDA receptor current ratios in the ventral tegmental area dopamine neurons of midbrain slices after a single injection of morphine (10 mg/kg, s.c., sliced prepared 24 h afterwards), in contrast to the wildtype mice. The results indicate impaired drug-induced state-dependency in GluA1 knockout mice, correlating with impaired opioid-induced glutamate receptor neuroplasticity. PMID:22675452

  11. Malondialdehyde-acetaldehyde (MAA) adducted surfactant protein induced lung inflammation is mediated through scavenger receptor a (SR-A1).

    PubMed

    Sapkota, Muna; DeVasure, Jane M; Kharbanda, Kusum K; Wyatt, Todd A

    2017-02-13

    Co-exposure to cigarette smoke and alcohol leads to the generation of high concentrations of acetaldehyde and malondialdehyde in the lung. These aldehydes being highly electrophilic in nature react with biologically relevant proteins such as surfactant protein D (SPD) through a Schiff base reaction to generate SPD adducted malondialdehyde-acetaldehyde adduct (SPD-MAA) in mouse lung. SPD-MAA results in an increase in lung pro-inflammatory chemokine, keratinocyte chemoattractant (KC), and the recruitment of lung lavage neutrophils. Previous in vitro studies in bronchial epithelial cells and macrophages show that scavenger receptor A (SR-A1/CD204) is a major receptor for SPD-MAA. No studies have yet examined the in vivo role of SR-A1 in MAA-mediated lung inflammation. Therefore, we hypothesize that in the absence of SR-A1, MAA-induced inflammation in the lung is reduced or diminished. To test this hypothesis, C57BL/6 WT and SR-A1 KO mice were nasally instilled with 50 μg/mL of SPD-MAA for 3 weeks (wks). After 3 weeks, bronchoalveolar lavage (BAL) fluid was collected and assayed for a total cell count, a differential cell count and CXCL1 (KC) chemokine. Lung tissue sections were stained with hematoxylin and eosin (H&E) and antibodies to MAA adduct. Results showed that BAL cellularity and influx of neutrophils were decreased in SR-A1 KO mice as compared to WT following repetitive SPD-MAA exposure. MAA adduct staining in the lung epithelium was decreased in SR-A1 KO mice. In comparison to WT, no increase in CXCL1 was observed in BAL fluid from SR-A1 KO mice over time. Overall, the data demonstrate that SR-A1/CD204 plays an important role in SPD-MAA induced inflammation in lung.

  12. Adenosine A1 Receptors in Mouse Pontine Reticular Formation Modulate Nociception Only in the Presence of Systemic Leptin

    PubMed Central

    Watson, Sarah L.; Watson, Christopher J.; Baghdoyan, Helen A.; Lydic, Ralph

    2014-01-01

    Human obesity is associated with increased leptin levels and pain, but the specific brain regions and neurochemical mechanisms underlying this association remain poorly understood. This study used adult male C57BL/6J (B6, n = 14) mice and leptin-deficient, obese B6.Cg-Lepob/J (obese, n = 10) mice to evaluate the hypothesis that nociception is altered by systemic leptin levels and by adenosine A1 receptors in the pontine reticular formation. Nociception was quantified as paw withdrawal latency (PWL) in s after onset of a thermal stimulus. PWL was converted to percent maximum possible effect (%MPE). After obtaining baseline PWL measures, the pontine reticular formation was microinjected with saline (control), three concentrations of the adenosine A1 receptor agonist N6-p-sulfophenyladenosine (SPA), or super-active mouse leptin receptor antagonist (SMLA) followed by SPA 15 min later, and PWL was again quantified. In obese, leptin-deficient mice, nociception was quantified before and during leptin replacement via subcutaneous osmotic pumps. SPA was administered into the pontine reticular formation of leptin-replaced mice and PWL testing was repeated. During baseline (before vehicle or SPA administration), PWL was significantly (p = 0.0013) lower in leptin-replaced obese mice than in B6 mice. Microinjecting SPA into the pontine reticular formation of B6 mice caused a significant (p = 0.0003) concentration-dependent increase in %MPE. SPA also significantly (p < 0.05) increased %MPE in B6 mice and in leptin-replaced obese mice, but not in leptin-deficient obese mice. Microinjection of the mouse super-active leptin antagonist (SMLA) into the pontine reticular formation before SPA did not alter PWL. The results show for the first time that pontine reticular formation administration of the adenosine A1 receptor agonist SPA produced antinociception only in the presence of systemic leptin. The concentration-response data support the interpretation that adenosine A1 receptors

  13. Non-genomic effects of the NR4A1/Nur77/TR3/NGFIB orphan nuclear receptor.

    PubMed

    Pawlak, Alicja; Strzadala, Leon; Kalas, Wojciech

    2015-03-01

    The orphan nuclear receptor NR4A1/Nur77/TR3/NGFIB acts primarily as a transcription factor to regulate the expression of multiple genes. However, increasing research attention has recently been given to non-genomic activities of NR4A1. The first description of a non-genomic action of NR4A1 referred to the conversion of anti-apoptotic Bcl-2 into a pro-apoptotic protein by direct interaction with NR4A1. In response to certain apoptotic stimuli, NR4A1 translocates from the nucleus to the mitochondrial outer membrane (MOM) where it associates with Bcl-2 and thereby causes apoptosis. Afterwards, it appeared that NR4A1 could also bind and convert other anti-apoptotic Bcl-2 family members. The latest studies indicate a significant role of NR4A1 in the process of autophagy. For example, a new NR4A1-mediated pathway specific for melanoma cells has been described where NR4A1 interacts with the adenine nucleotide translocase 1 (ANT1) on the mitochondrial inner membrane (MIM) leading to induction of the autophagy pathway. Moreover, NR4A1 interaction with cytoplasmic p53 may also contribute to the induction of autophagy. In addition to mitochondria, NR4A1 could be translocated to the outer membrane of the endoplasmic reticulum (ER) and associate with Bcl-2 or translocon-associated protein subunit γ (TRAPγ) causing ER stress-induced apoptosis. NR4A1 also contributes to the proteasomal degradation of β-catenin in colon cancer cells in vitro and in vivo, as well as to the stabilization of hypoxia-inducible factor-1α (HIF-1α) under non-hypoxic conditions. This review summarizes research findings on non-genomic effects of NR4A1 in normal and cancer cells. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. The EphA2 Receptor and EphrinA1 Ligand in Solid Tumors: Function and Therapeutic Targeting

    PubMed Central

    Wykosky, Jill; Debinski, Waldemar

    2013-01-01

    The Eph receptor tyrosine kinases and ephrin ligands have been studied extensively for their roles in developmental processes. In recent years, Eph receptors and ephrins have been found to be integral players in cancer formation and progression. Among these are EphA2 and ephrinA1, which are involved in the development and maintenance of many different types of solid tumors. The function of EphA2 and ephrinA1 in tumorigenesis and tumor progression is complex and seems to be dependent on cell type and microenvironment. These variables affect the expression of the EphA2 and ephrinA1 proteins, the pathways through which they induce signaling, and the functional consequences of that signaling on the behavior of tumor cells and tumor-associated cells. This review will specifically focus on the roles that EphA2 and ephrinA1 play in the different cell types that contribute to the malignancy of solid tumors, with emphasis on the opportunities for therapeutic targeting. PMID:19074825

  15. Mediation of the neuroprotective action of R-phenylisopropyl-adenosine through a centrally located adenosine A1 receptor.

    PubMed Central

    MacGregor, D. G.; Miller, W. J.; Stone, T. W.

    1993-01-01

    1. Systemic injections of kainic acid, 10 mg kg-1, into adult rats resulted in lesions in the hippocampus, as assessed by peripheral benzodiazepine ligand binding. Co-administration of clonazepam at 1 mg kg-1 or 0.2 mg kg-1 prevented major seizures associated with kainate injections, but did not alter significantly the production of hippocampal damage. 2. The co-administration of the adenosine A1 agonist R-phenylisopropyladenosine (R-PIA, 25 micrograms kg-1, i.p.) abolished the lesions induced by kainic acid. 3. The presence of the selective A1 antagonist, 8-cyclopentyl-1,3-dipropylxanthine (250 or 50 micrograms kg-1, i.p.) abolished the R-PIA neuroprotective action. 4. The A1/A2 antagonist, 8-(p-sulphophenyl)theophylline (20 mg kg-1, i.p.) which cannot cross the blood brain barrier, did not alter significantly the neuroprotective action of R-PIA, indicating that the neuroprotective action of the purine may be predominantly central. 5. The time course of the neuroprotection was also examined. R-PIA was effective when administered 2 h before or after kainate administration. 6. The results emphasise the potential utility of systemically active adenosine A1 receptor ligands in reducing CNS gliosis induced by the activation of excitatory amino acid receptors. PMID:8220909

  16. Presynaptic M1, M2, and A1 receptors play roles in tetanic fade induced by pancuronium or cisatracurium.

    PubMed

    Bornia, Elaine Campana Sanches; Bando, Erika; Machinski, Miguel; Pereira, Monalisa Wolski; Alves-Do-Prado, Wilson

    2009-01-01

    We investigated whether presynaptic facilitatory M1 and/or inhibitory M2 muscarinic receptors contributed to pancuronium- and cisatracurium-induced tetanic fade. Phrenic nerve-diaphragm muscle preparations of rats were indirectly stimulated with tetanic frequency (75 +/- 3.3 Hz; mean +/- SD). Doses of pancuronium, cisatracurium, hexamethonium, and d-tubocurarine for producing approximately 25% fade were determined. The effects of pirenzepine and methoctramine, blockers of presynaptic M1 and M2 receptors, respectively, on the tetanic fade were investigated. The concentrations required for approximately 25% fade were 413 microM for hexamethonium (26.8 +/- 2.4% 4% fade), 55 nM for d-tubocurarine (28.7 +/- 2.55% fade), 0.32 microM for pancuronium (25.4 +/- 2.2% fade), and 0.32 microM for cisatracurium (24.7 +/- 0.8% fade). Pirenzepine or methoctramine alone did not produce the fade. Methoctramine, 1 microM, attenuated the fade induced by hexamethonium (to 16.0 +/- 2.5% fade), d-tubocurarine (to 6.0 +/- 1.6 fade), pancuronium (to 8.0 +/- 4.0% fade), and cisatracurium (to 11.0 +/- 3.3% fade). 10 nM pirenzepine attenuated only the fades produced by pancuronium (to 5.0 +/- 0.11% fade) and cisatracurium (to 13.3 +/- 5.3% fade). Cisatracurium (0.32 microM) showed antiacetylcholinesterase activity (in plasma, 14.2 +/- 1.6%; 6%; in erythrocyt 17.2 +/- 2.66%) similar to that of pancuronium (0.32 microM). The selective A1 receptor blocker, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; 2.5 nM), also attenuated the fades induced by pancuronium and cisatracurium. The tetanic fades produced by pancuronium and cisatracurium depend on the activation of presynaptic inhibitory M2 receptors; these agents also have anticholinesterase activities. The fades induced by these agents also depend on the activation of presynaptic inhibitory A1 receptors through the activation of stimulatory M1 receptors by acetylcholine.

  17. A novel mechanism of renal blood flow autoregulation and the autoregulatory role of A1 adenosine receptors in mice.

    PubMed

    Just, Armin; Arendshorst, William J

    2007-11-01

    Autoregulation of renal blood flow (RBF) is mediated by a fast myogenic response (MR; approximately 5 s), a slower tubuloglomerular feedback (TGF; approximately 25 s), and potentially additional mechanisms. A1 adenosine receptors (A1AR) mediate TGF in superficial nephrons and contribute to overall autoregulation, but the impact on the other autoregulatory mechanisms is unknown. We studied dynamic autoregulatory responses of RBF to rapid step increases of renal artery pressure in mice. MR was estimated from autoregulation within the first 5 s, TGF from that at 5-25 s, and a third mechanism from 25-100 s. Genetic deficiency of A1AR (A1AR-/-) reduced autoregulation at 5-25 s by 50%, indicating a residual fourth mechanism resembling TGF kinetics but independent of A1AR. MR and third mechanism were unaltered in A1AR-/-. Autoregulation in A1AR-/- was faster at 5-25 than at 25-100 s suggesting two separate mechanisms. Furosemide in wild-type mice (WT) eliminated the third mechanism and enhanced MR, indicating TGF-MR interaction. In A1AR-/-, furosemide did not further impair autoregulation at 5-25 s, but eliminated the third mechanism and enhanced MR. The resulting time course was the same as during furosemide in WT, indicating that A1AR do not affect autoregulation during furosemide inhibition of TGF. We conclude that at least one novel mechanism complements MR and TGF in RBF autoregulation, that is slower than MR and TGF and sensitive to furosemide, but not mediated by A1AR. A fourth mechanism with kinetics similar to TGF but independent of A1AR and furosemide might also contribute. A1AR mediate classical TGF but not TGF-MR interaction.

  18. Prolonged P300 latency in children with the D[sub 2] dopamine receptor A1 allele

    SciTech Connect

    Noble, E.P.; Berman, S.M.; Ozkaragoz, T.Z.

    1994-04-01

    Previous studies have indicated the presence of a hereditary component in the generation of the P300, or P3, a late positive component of the event-related potential. Moreover, the dopaminergic system has been implicated in the P3. In the present study, 98 healthy Caucasian boys, mean age of 12.5 years and of above-average intelligence, were studied. The sample was composed of 32 sons of active alcoholic (SAA) fathers, 36 sons of recovering alcoholic (SRA) fathers, and 30 sons of social drinker (SSD) fathers, with none of them having yet begun to consume alcohol or other drugs. TaqI A D[sub 2] dopaminemore » receptor alleles (A1 and A2) were determined. A significant difference in the frequency of the A1 allele was found among these three groups of boys, with the SAA group having the highest A1 allele frequency (.313), followed by the SRA (.139) and the SSD (.133) groups. The relationship of the A1 and A2 alleles to P3 amplitude and latency was also determined. The results showed no significant difference in P3 amplitude between boys with the A1 and A2 allele. However, P3 latency was significantly longer in the total sample of boys with the A1 allele compared with those carrying the A2 allele. These findings suggest that polymorphism of the D[sub 2] dopamine receptor gene is an important determinant of P3 latency. 84 refs., 2 figs., 3 tabs.« less

  19. Activation of microglial cells triggers a release of brain-derived neurotrophic factor (BDNF) inducing their proliferation in an adenosine A2A receptor-dependent manner: A2A receptor blockade prevents BDNF release and proliferation of microglia

    PubMed Central

    2013-01-01

    Background Brain-derived neurotrophic factor (BDNF) has been shown to control microglial responses in neuropathic pain. Since adenosine A2A receptors (A2ARs) control neuroinflammation, as well as the production and function of BDNF, we tested to see if A2AR controls the microglia-dependent secretion of BDNF and the proliferation of microglial cells, a crucial event in neuroinflammation. Methods Murine N9 microglial cells were challenged with lipopolysaccharide (LPS, 100 ng/mL) in the absence or in the presence of the A2AR antagonist, SCH58261 (50 nM), as well as other modulators of A2AR signaling. The BDNF cellular content and secretion were quantified by Western blotting and ELISA, A2AR density was probed by Western blotting and immunocytochemistry and cell proliferation was assessed by BrdU incorporation. Additionally, the A2AR modulation of LPS-driven cell proliferation was also tested in primary cultures of mouse microglia. Results LPS induced time-dependent changes of the intra- and extracellular levels of BDNF and increased microglial proliferation. The maximal LPS-induced BDNF release was time-coincident with an LPS-induced increase of the A2AR density. Notably, removing endogenous extracellular adenosine or blocking A2AR prevented the LPS-mediated increase of both BDNF secretion and proliferation, as well as exogenous BDNF-induced proliferation. Conclusions We conclude that A2AR activation plays a mandatory role controlling the release of BDNF from activated microglia, as well as the autocrine/paracrine proliferative role of BDNF. PMID:23363775

  20. Association analysis of the vitamin D receptor gene, the type I collagen gene COL1A1, and the estrogen receptor gene in idiopathic osteoarthritis.

    PubMed

    Loughlin, J; Sinsheimer, J S; Mustafa, Z; Carr, A J; Clipsham, K; Bloomfield, V A; Chitnavis, J; Bailey, A; Sykes, B; Chapman, K

    2000-03-01

    Evidence has accumulated supporting a role for genes in the etiology of osteoarthritis (OA). Several candidates have been targeted as potential susceptibility loci including genes that are involved in the regulation of bone density. Genetic association analysis has suggested a role for the vitamin D receptor gene (VDR) and the estrogen receptor gene (ER) in susceptibility. Such findings must be tested in additional independent cohorts. We tested for association of these 2 genes, plus a third gene implicated in bone density, COL1A1, with idiopathic OA. A case-control cohort of 371 affected probands and 369 unaffected spouses was used. Association was tested using 4 intragenic single nucleotide polymorphisms (SNP), one each for the VDR and COL1A1 genes, and 2 for the ER gene. The VDR and ER SNP are the same SNP that have been associated with OA. All 4 SNP affect restriction enzyme sites and were genotyped using polymerase chain reaction and enzyme digestion. Allele and genotype distributions for each SNP were compared between cases and controls and analyzed using Fisher's exact test. There was no evidence of association of the VDR or the ER gene SNP to OA. There was weak evidence of association of the COL1A1 SNP in female cases (p = 0.017), reflected by a difference in the distribution of genotypes at this SNP between female cases and controls (p = 0.027). However, when corrected for multiple testing, these results were not significant. If the VDR, ER, or COL1A1 genes do encode predisposition to OA then the 4 SNP tested are not associated with major susceptibility alleles at these 3 loci.

  1. Phosphatidic acid phospholipase A1 mediates ER–Golgi transit of a family of G protein–coupled receptors

    PubMed Central

    Kunduri, Govind; Yuan, Changqing; Parthibane, Velayoudame; Nyswaner, Katherine M.; Kanwar, Ritu; Nagashima, Kunio; Britt, Steven G.; Mehta, Nickita; Kotu, Varshika; Porterfield, Mindy; Tiemeyer, Michael; Dolph, Patrick J.; Acharya, Usha

    2014-01-01

    The coat protein II (COPII)–coated vesicular system transports newly synthesized secretory and membrane proteins from the endoplasmic reticulum (ER) to the Golgi complex. Recruitment of cargo into COPII vesicles requires an interaction of COPII proteins either with the cargo molecules directly or with cargo receptors for anterograde trafficking. We show that cytosolic phosphatidic acid phospholipase A1 (PAPLA1) interacts with COPII protein family members and is required for the transport of Rh1 (rhodopsin 1), an N-glycosylated G protein–coupled receptor (GPCR), from the ER to the Golgi complex. In papla1 mutants, in the absence of transport to the Golgi, Rh1 is aberrantly glycosylated and is mislocalized. These defects lead to decreased levels of the protein and decreased sensitivity of the photoreceptors to light. Several GPCRs, including other rhodopsins and Bride of sevenless, are similarly affected. Our findings show that a cytosolic protein is necessary for transit of selective transmembrane receptor cargo by the COPII coat for anterograde trafficking. PMID:25002678

  2. 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.

  3. Homeostatic action of adenosine A3 and A1 receptor agonists on proliferation of hematopoietic precursor cells.

    PubMed

    Hofer, Michal; Pospísil, Milan; Znojil, Vladimír; Holá, Jirina; Streitová, Denisa; Vacek, Antonín

    2008-07-01

    Two adenosine receptor agonists, N6-(3-iodobenzyl)adenosine-5'-N-methyluronamide (IB-MECA) and N6-cyclopentyladenosine (CPA), which selectively activate adenosine A3 and A1 receptors, respectively, were tested for their ability to influence proliferation of granulocytic and erythroid cells in femoral bone marrow of mice using morphological criteria. Agonists were given intraperitoneally to mice in repeated isomolar doses of 200 nmol/kg. Three variants of experiments were performed to investigate the action of the agonists under normal resting state of mice and in phases of cell depletion and subsequent regeneration after treatment with the cytotoxic drug 5-fluorouracil. In the case of granulopoiesis, IB-MECA 1) increased by a moderate but significant level proliferation of cells under normal resting state; 2) strongly increased proliferation of cells in the cell depletion phase; but 3) did not influence cell proliferation in the regeneration phase. CPA did not influence cell proliferation under normal resting state and in the cell depletion phase, but strongly suppressed the overshooting cell proliferation in the regeneration phase. The stimulatory effect of IB-MECA on cell proliferation of erythroid cells was observed only when this agonist was administered during the cell depletion phase. CPA did not modulate erythroid proliferation in any of the functional states investigated, probably due to the lower demand for cell production as compared with granulopoiesis. The results indicate opposite effects of the two adenosine receptor agonists on proliferation of hematopoietic cells and suggest the plasticity and homeostatic role of the adenosine receptor expression.

  4. Deletion of the GluA1 AMPA receptor subunit impairs recency-dependent object recognition memory

    PubMed Central

    Sanderson, David J.; Hindley, Emma; Smeaton, Emily; Denny, Nick; Taylor, Amy; Barkus, Chris; Sprengel, Rolf; Seeburg, Peter H.; Bannerman, David M.

    2011-01-01

    Deletion of the GluA1 AMPA receptor subunit impairs short-term spatial recognition memory. It has been suggested that short-term recognition depends upon memory caused by the recent presentation of a stimulus that is independent of contextual–retrieval processes. The aim of the present set of experiments was to test whether the role of GluA1 extends to nonspatial recognition memory. Wild-type and GluA1 knockout mice were tested on the standard object recognition task and a context-independent recognition task that required recency-dependent memory. In a first set of experiments it was found that GluA1 deletion failed to impair performance on either of the object recognition or recency-dependent tasks. However, GluA1 knockout mice displayed increased levels of exploration of the objects in both the sample and test phases compared to controls. In contrast, when the time that GluA1 knockout mice spent exploring the objects was yoked to control mice during the sample phase, it was found that GluA1 deletion now impaired performance on both the object recognition and the recency-dependent tasks. GluA1 deletion failed to impair performance on a context-dependent recognition task regardless of whether object exposure in knockout mice was yoked to controls or not. These results demonstrate that GluA1 is necessary for nonspatial as well as spatial recognition memory and plays an important role in recency-dependent memory processes. PMID:21378100

  5. Sodium intake, RAAS-blockade and progressive renal disease.

    PubMed

    de Borst, Martin H; Navis, Gerjan

    2016-05-01

    Pharmacological blockade of the renin-angiotensin-aldosterone system (RAAS) by angiotensin converting enzyme inhibitors or angiotensin receptor blockers is the current standard treatment to prevent progressive renal function loss in patients with chronic kidney disease. Yet in many patients the renal protective effect of RAAS-blockade is incomplete. Short-term clinical studies have demonstrated that dietary sodium restriction potentiates the antiproteinuric effect of RAAS-blockade. More recently, it was shown that this effect is accompanied by a lower risk of end-stage renal disease and adverse cardiovascular outcomes. The modulation of RAAS-blockade efficacy by sodium intake is likely multifactorial, and is mediated by effects of sodium on local tissue RAAS in kidney, vasculature and brain, and by effects on the immune system. Despite the evidence showing the beneficial effects of even a moderate sodium restriction (∼2.5g/d), it remains difficult to realize in clinical practice. In an analysis based on 24-h urinary sodium excretion data from more than 10,000 CKD patients and renal transplant recipients, we found that sodium intake in these patients is on average 3.8g/d, closely resembling the global general population (3.95g/d). Behavioral approaches including the use of online dietary coaching (ehealth) and feedback using data from 24-h urine collections may be useful to successfully lower dietary sodium intake, aiming to improve cardio-renal outcomes in patients with CKD. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Diadenosine tetraphosphate stimulates atrial ANP release via A(1) receptor: involvement of K(ATP) channel and PKC.

    PubMed

    Yuan, Kuichang; Cao, Chunhua; Bai, Guang Yi; Kim, Sung Zoo; Kim, Suhn Hee

    2007-07-01

    Diadenosine polyphosphates (APnAs) are endogenous compounds and exert diverse cardiovascular functions. However, the effects of APnAs on atrial ANP release and contractility have not been studied. In this study, the effects of diadenosine tetraphosphate (AP4A) on atrial ANP release and contractility, and their mechanisms were studied using isolated perfused rat atria. Treatment of atria with AP4A resulted in decreases in atrial contractility and extracellular fluid (ECF) translocation whereas ANP secretion and cAMP levels in perfusate were increased in a dose-dependent manner. These effects of AP4A were attenuated by A(1) receptor antagonist but not by A(2A) or A(3) receptor antagonist. Other purinoceptor antagonists also did not show any effects on AP4A-induced ANF release and contractility. The increment of ANP release and negative inotropy induced by AP4A was similar to those induced by AP3A, AP5A, and AP6A. Protein kinase A inhibitors accentuated AP4A-induced ANP secretion. In contrast, an inhibitor of phospholipase C, protein kinase C or sarcolemma K(ATP) channel completely blocked AP4A-induced ANP secretion. However, an inhibitor of adenylyl cyclase or mitochondria K(ATP) channel had no significant modification of AP4A effects. These results suggest that AP4A regulates atrial inotropy and ANP release mainly through A(1) receptor signaling involving phospholipase C-protein kinase C and sarcolemmal K(ATP) channel and that protein kinase A negatively modulates the effects of AP4A.

  7. Gustatory Receptor Neurons in Manduca sexta Contain a TrpA1-Dependent Signaling Pathway that Integrates Taste and Temperature

    PubMed Central

    2013-01-01

    Temperature modulates the peripheral taste response of many animals, in part by activating transient receptor potential (Trp) cation channels. We hypothesized that temperature would also modulate peripheral taste responses in larval Manduca sexta. We recorded excitatory responses of the lateral and medial styloconic sensilla to chemical stimuli at 14, 22, and 30 °C. The excitatory responses to 5 chemical stimuli—a salt (KCl), 3 sugars (sucrose, glucose, and inositol) and an alkaloid (caffeine)—were unaffected by temperature. In contrast, the excitatory response to the aversive compound, aristolochic acid (AA), increased robustly with temperature. Next, we asked whether TrpA1 mediates the thermally dependent taste response to AA. To this end, we 1) identified a TrpA1 gene in M. sexta; 2) demonstrated expression of TrpA1 in the lateral and medial styloconic sensilla; 3) determined that 2 TrpA1 antagonists (HC-030031 and mecamylamine) inhibit the taste response to AA, but not caffeine; and then 4) established that the thermal dependence of the taste response to AA is blocked by HC-030031. Taken together, our results indicate that TrpA1 serves as a molecular integrator of taste and temperature in M. sexta. PMID:23828906

  8. Negative Effects of SRD5A1 on Nuclear Activity of Progesterone Receptor Isoform B in JEG3 Cells.

    PubMed

    Miao, Zhuo; Sun, Min; Jiang, Feng; Yao, Yuanqing; Li, Yi

    2016-02-01

    Progesterone withdrawal signals labor in mammals. Elevated intracellular metabolism contributes to progesterone functional withdrawal through unknown mechanism, which is thought to act via progesterone receptor (PR). This study aims to investigate molecular mechanisms underlying progesterone withdrawal during pregnancy and labor. We investigated the role of 5α-reductase type I (SRD5A1) in enzymatic catalysis of progesterone and loss of PR function in a human trophoblast choriocarcinoma cell line JEG3. The PR isoform B (PR-B) was robustly expressed in JEG3 cells. The SRD5A1 small-interfering RNA knockdown led to significant increase in PR-B nuclear import, ectopic, whereas SRD5A1 overexpression resulted in remarkable inhibition of nuclear PR-B in P4-treated cells. Repression of SRD5A1 activated PR-B responsive gene, whereas overexpression of SRD5A1 possessed an inhibitory effect. JEG3 cell line is a valuable tool to study mechanisms responsible for loss of PR function and screening of drugs for preterm birth treatment. Our study aims to investigate the molecular mechanisms underlying progesterone withdrawal during pregnancy and labor. © The Author(s) 2015.

  9. Adenosine A1 Receptor Protects Against Cisplatin Ototoxicity by Suppressing the NOX3/STAT1 Inflammatory Pathway in the Cochlea

    PubMed Central

    Kaur, Tejbeer; Borse, Vikrant; Sheth, Sandeep; Sheehan, Kelly; Ghosh, Sumana; Tupal, Srinivasan; Jajoo, Sarvesh; Mukherjea, Debashree; Rybak, Leonard P.

    2016-01-01

    Cisplatin is a commonly used antineoplastic agent that produces ototoxicity that is mediated in part by increasing levels of reactive oxygen species (ROS) via the NOX3 NADPH oxidase pathway in the cochlea. Recent studies implicate ROS generation in mediating inflammatory and apoptotic processes and hearing loss by activating signal transducer and activator of transcription (STAT1). In this study, we show that the adenosine A1 receptor (A1AR) protects against cisplatin ototoxicity by suppressing an inflammatory response initiated by ROS generation via NOX3 NADPH oxidase, leading to inhibition of STAT1. Trans-tympanic administration of the A1AR agonist R-phenylisopropyladenosine (R-PIA) inhibited cisplatin-induced ototoxicity, as measured by auditory brainstem responses and scanning electron microscopy in male Wistar rats. This was associated with reduced NOX3 expression, STAT1 activation, tumor necrosis factor-α (TNF-α) levels, and apoptosis in the cochlea. In vitro studies in UB/OC-1 cells, an organ of Corti immortalized cell line, showed that R-PIA reduced cisplatin-induced phosphorylation of STAT1 Ser727 (but not Tyr701) and STAT1 luciferase activity by suppressing the ERK1/2, p38, and JNK mitogen-activated protein kinase (MAPK) pathways. R-PIA also decreased the expression of STAT1 target genes, such as TNF-α, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and reduced cisplatin-mediated apoptosis. These data suggest that the A1AR provides otoprotection by suppressing NOX3 and inflammation in the cochlea and could serve as an ideal target for otoprotective drug therapy. SIGNIFICANCE STATEMENT Cisplatin is a widely used chemotherapeutic agent for the treatment of solid tumors. Its use results in significant and permanent hearing loss, for which no US Food and Drug Administration-approved treatment is currently available. In this study, we targeted the cochlear adenosine A1 receptor (A1AR) by trans-tympanic injections of the agonist R

  10. Adenosine A1 Receptor Protects Against Cisplatin Ototoxicity by Suppressing the NOX3/STAT1 Inflammatory Pathway in the Cochlea.

    PubMed

    Kaur, Tejbeer; Borse, Vikrant; Sheth, Sandeep; Sheehan, Kelly; Ghosh, Sumana; Tupal, Srinivasan; Jajoo, Sarvesh; Mukherjea, Debashree; Rybak, Leonard P; Ramkumar, Vickram

    2016-04-06

    Cisplatin is a commonly used antineoplastic agent that produces ototoxicity that is mediated in part by increasing levels of reactive oxygen species (ROS) via the NOX3 NADPH oxidase pathway in the cochlea. Recent studies implicate ROS generation in mediating inflammatory and apoptotic processes and hearing loss by activating signal transducer and activator of transcription (STAT1). In this study, we show that the adenosine A1 receptor (A1AR) protects against cisplatin ototoxicity by suppressing an inflammatory response initiated by ROS generation via NOX3 NADPH oxidase, leading to inhibition of STAT1. Trans-tympanic administration of the A1AR agonist R-phenylisopropyladenosine (R-PIA) inhibited cisplatin-induced ototoxicity, as measured by auditory brainstem responses and scanning electron microscopy in male Wistar rats. This was associated with reduced NOX3 expression, STAT1 activation, tumor necrosis factor-α (TNF-α) levels, and apoptosis in the cochlea. In vitro studies in UB/OC-1 cells, an organ of Corti immortalized cell line, showed that R-PIA reduced cisplatin-induced phosphorylation of STAT1 Ser(727) (but not Tyr(701)) and STAT1 luciferase activity by suppressing the ERK1/2, p38, and JNK mitogen-activated protein kinase (MAPK) pathways.R-PIA also decreased the expression of STAT1 target genes, such as TNF-α, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and reduced cisplatin-mediated apoptosis. These data suggest that the A1AR provides otoprotection by suppressing NOX3 and inflammation in the cochlea and could serve as an ideal target for otoprotective drug therapy. Cisplatin is a widely used chemotherapeutic agent for the treatment of solid tumors. Its use results in significant and permanent hearing loss, for which no US Food and Drug Administration-approved treatment is currently available. In this study, we targeted the cochlear adenosine A1 receptor (A1AR) by trans-tympanic injections of the agonist R

  11. Proximal tubule sphingosine kinase-1 has a critical role in A1 adenosine receptor-mediated renal protection from ischemia

    PubMed Central

    Park, Sang Won; Kim, Mihwa; Kim, Joo Yun; Brown, Kevin M.; Haase, Volker H.; D’Agati, Vivette D.; Lee, H. Thomas

    2012-01-01

    Renal ischemia reperfusion injury is a major cause of acute kidney injury. We previously found that renal A1 adenosine receptor (A1AR) activation attenuated multiple cell death pathways including necrosis, apoptosis and inflammation. Here, we tested whether induction of cytoprotective sphingosine kinase (SK)-1 and sphingosine-1 phosphate (S1P) synthesis might be the mechanism of protection. A selective A1AR agonist (CCPA) increased the synthesis of S1P and selectively induced SK-1 in mouse kidney and HK-2 cells. This agonist failed to protect SK1-knockout but protected SK2-knockout mice against renal ischemia reperfusion injury indicating a critical role of SK1 in A1AR-mediated renal protection. Inhibition of SK prevented A1AR-mediated defense against necrosis and apoptosis in HK-2 cells. A selective S1P1R antagonist (W146) and global in vivo gene knockdown of S1P1Rs with small interfering RNA completely abolished the renal protection provided by CCPA. Mice selectively deficient in renal proximal tubule S1P1Rs (S1P1Rflox/flox PEPCKCre/−) were not protected against renal ischemia reperfusion injury by CCPA. Mechanistically, CCPA increased nuclear translocation of hypoxia inducible factor-1α in HK-2 cells and selective hypoxia inducible factor-1α inhibition blocked A1AR-mediated induction of SK1. Thus, proximal tubule SK-1 has a critical role in A1AR-mediated protection against renal ischemia reperfusion injury. PMID:22695326

  12. Food cravings, food addiction, and a dopamine-resistant (DRD2 A1) receptor polymorphism in Asian American college students.

    PubMed

    Yeh, Joanna; Trang, Amy; Henning, Susanne M; Wilhalme, Holly; Carpenter, Catherine; Heber, David; Li, Zhaoping

    2016-01-01

    In an era where obesity remains an important public health concern, food addiction has emerged as a possible contributor to obesity. The DRD2 gene is the most studied polymorphism. The aim of this study was to investigate a relationship between food addiction questionnaires, body composition measurements, and a dopamine- resistant receptor polymorphism (DRD2 A1) among Asian Americans. A total of 84 Asian American college students were recruited. Participants underwent body composition measurement via bioelectrical impedance, answered questionnaires (Food Craving Inventory and Power of Food Scale), and had blood drawn for genotyping (PCR). There was no difference in body composition (BMI, percent body fat) between the A1 (A1A1 or A1A2) and A2 (A2A2) groups. There were statistically significant differences in food cravings of carbohydrates and fast food on the Food Craving Inventory between the A1 and A2 groups (p=0.03), but not for sugar or fat. Among Asian college females, there was also a difference on the Power of Food questionnaire (p=0.04), which was not seen among men. 13 out of 55 women also had >30% body fat at a BMI of 21.4 to 28.5 kg/m2. Greater carbohydrate and fast food craving was associated with the DRD2 A1 versus A2 allele among Asian Americans. Further studies examining the ability of dopamine agonists to affect food craving and to reduce body fat in Asian American are warranted. More studies in food addiction among obese Asian Americans are needed with careful definition of obesity, specifically for Asian women.

  13. Activity-dependent ubiquitination of GluA1 mediates a distinct AMPA receptor endocytosis and sorting pathway.

    PubMed

    Schwarz, Lindsay A; Hall, Benjamin J; Patrick, Gentry N

    2010-12-08

    The accurate trafficking of AMPA receptors (AMPARs) to and from the synapse is a critical component of learning and memory in the brain, whereas dysfunction of AMPAR trafficking is hypothesized to be an underlying mechanism of Alzheimer's disease. Previous work has shown that ubiquitination of integral membrane proteins is a common posttranslational modification used to mediate endocytosis and endocytic sorting of surface proteins in eukaryotic cells. Here we report that mammalian AMPARs become ubiquitinated in response to their activation. Using a mutant of GluA1 that is unable to be ubiquitinated at lysines on its C-terminus, we demonstrate that ubiquitination is required for internalization of surface AMPARs and their trafficking to the lysosome in response to the AMPAR agonist AMPA but not for internalization of AMPARs in response to the NMDA receptor agonist NMDA. Through overexpression or RNA interference-mediated knockdown, we identify that a specific E3 ligase, Nedd4-1 (neural-precursor cell-expressed developmentally downregulated gene 4-1), is necessary for this process. Finally, we show that ubiquitination of GluA1 by Nedd4-1 becomes more prevalent as neurons mature. Together, these data show that ubiquitination of GluA1-containing AMPARs by Nedd4-1 mediates their endocytosis and trafficking to the lysosome. Furthermore, these results provide insight into how hippocampal neurons regulate AMPAR trafficking and degradation with high specificity in response to differing neuronal signaling cues and suggest that changes to this pathway may occur as neurons mature.

  14. Human Anti-Oxidation Protein A1M—A Potential Kidney Protection Agent in Peptide Receptor Radionuclide Therapy

    PubMed Central

    Ahlstedt, Jonas; Tran, Thuy A.; Strand, Sven-Erik; Gram, Magnus; Åkerström, Bo

    2015-01-01

    Peptide receptor radionuclide therapy (PRRT) has been in clinical use for 15 years to treat metastatic neuroendocrine tumors. PRRT is limited by reabsorption and retention of the administered radiolabeled somatostatin analogues in the proximal tubule. Consequently, it is essential to develop and employ methods to protect the kidneys during PRRT. Today, infusion of positively charged amino acids is the standard method of kidney protection. Other methods, such as administration of amifostine, are still under evaluation and show promising results. α1-microglobulin (A1M) is a reductase and radical scavenging protein ubiquitously present in plasma and extravascular tissue. Human A1M has antioxidation properties and has been shown to prevent radiation-induced in vitro cell damage and protect non-irradiated surrounding cells. It has recently been shown in mice that exogenously infused A1M and the somatostatin analogue octreotide are co-localized in proximal tubules of the kidney after intravenous infusion. In this review we describe the current situation of kidney protection during PRRT, discuss the necessity and implications of more precise dosimetry and present A1M as a new, potential candidate for renal protection during PRRT and related targeted radionuclide therapies. PMID:26694383

  15. Effect of long term caffeine treatment on A1 and A2 adenosine receptor binding and on mRNA levels in rat brain.

    PubMed

    Johansson, B; Ahlberg, S; van der Ploeg, I; Brené, S; Lindefors, N; Persson, H; Fredholm, B B

    1993-04-01

    The effect of long-term oral treatment with caffeine on A1 and A2 receptors in the rat brain was studied. Caffeine was added to the drinking water and the animals were sacrificed after a 12 day treatment period. The plasma caffeine concentration was close to 100 microM. A1 receptors were studied using quantitative autoradiography with [3H]cyclohexyladenosine (CHA). Caffeine treatment increased the number of A1 receptors in the CA3 subfield of the hippocampus from 337 to 393 fmol/mg with no change in KD (0.692 vs. 0.675 nM). A1 mRNA was measured using Northern blots and quantitative in situ hybridization. There was no increase in A1 mRNA. A2a receptors, located in dopamine rich regions of the rat brain, were studied with quantitative autoradiography using [3H]CGS 21680 as the ligand, and the A2a mRNA was determined using quantitative in situ hybridization. Caffeine treatment produced no significant change in either receptor number or mRNA, even though the apparent Bmax tended to increase from 322 +/- 8 to 352 +/- 8 fmol/mg. The results show that treatment with caffeine in a dose that causes tolerance to several effects of caffeine and increases some effects of adenosine analogues increases the number of A1 receptors without any change in A1 mRNA, suggesting that the adaptive changes are at a post-translational level. There were no significant changes in A2 receptors indicating that the two types are regulated differently and/or that the amount of endogenous agonist is sufficient to regulate A1, but not A2 receptors.

  16. Embryonic caffeine exposure acts via A1 adenosine receptors to alter adult cardiac function and DNA methylation in mice.

    PubMed

    Buscariollo, Daniela L; Fang, Xiefan; Greenwood, Victoria; Xue, Huiling; Rivkees, Scott A; Wendler, Christopher C

    2014-01-01

    Evidence indicates that disruption of normal prenatal development influences an individual's risk of developing obesity and cardiovascular disease as an adult. Thus, understanding how in utero exposure to chemical agents leads to increased susceptibility to adult diseases is a critical health related issue. Our aim was to determine whether adenosine A1 receptors (A1ARs) mediate the long-term effects of in utero caffeine exposure on cardiac function and whether these long-term effects are the result of changes in DNA methylation patterns in adult hearts. Pregnant A1AR knockout mice were treated with caffeine (20 mg/kg) or vehicle (0.09% NaCl) i.p. at embryonic day 8.5. This caffeine treatment results in serum levels equivalent to the consumption of 2-4 cups of coffee in humans. After dams gave birth, offspring were examined at 8-10 weeks of age. A1AR+/+ offspring treated in utero with caffeine were 10% heavier than vehicle controls. Using echocardiography, we observed altered cardiac function and morphology in adult mice exposed to caffeine in utero. Caffeine treatment decreased cardiac output by 11% and increased left ventricular wall thickness by 29% during diastole. Using DNA methylation arrays, we identified altered DNA methylation patterns in A