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Sample records for agonist carbachol cch

  1. The Cholinergic Agonist Carbachol Increases the Frequency of Spontaneous GABAergic Synaptic Currents in Dorsal Raphe Serotonergic Neurons in the Mouse

    PubMed Central

    Yang, Chun; Brown, Ritchie E.

    2013-01-01

    Dorsal raphe nucleus (DRN) serotonin (5-HT) neurons play an important role in feeding, mood control and stress responses. One important feature of their activity across the sleep-wake cycle is their reduced firing during rapid-eye-movement (REM) sleep which stands in stark contrast to the wake/REM-on discharge pattern of brainstem cholinergic neurons. A prominent model of REM sleep control posits a reciprocal interaction between these cell groups. 5-HT inhibits cholinergic neurons, and activation of nicotinic receptors can excite DRN 5-HT neurons but the cholinergic effect on inhibitory inputs is incompletely understood. Here, in vitro, in DRN brain slices prepared from GAD67-GFP knock-in mice, a brief (3 min) bath application of carbachol (50 μM) increased the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) in GFP-negative, putative serotonin neurons but did not affect miniature (tetrodotoxin-insensitive) IPSCs. Carbachol had no direct postsynaptic effect. Thus, carbachol likely increases the activity of local GABAergic neurons which synapse on 5-HT neurons. Removal of dorsal regions of the slice including the ventrolateral periaqueductal gray (vlPAG) region where GABAergic neurons projecting to the DRN have been identified, abolished the effect of carbachol on sIPSCs whereas removal of ventral regions containing the oral region of the pontine reticular nucleus (PnO) did not. In addition, carbachol directly excited GFP-positive, GABAergic vlPAG neurons. Antagonism of both muscarinic and nicotinic receptors completely abolished the effects of carbachol. We suggest cholinergic neurons inhibit DRN 5-HT neurons when acetylcholine levels are lower i.e. during quiet wakefulness and the beginning of REM sleep periods, in part via excitation of muscarinic and nicotinic receptors located on local vlPAG and DRN GABAergic neurons. Higher firing rates or burst firing of cholinergic neurons associated with attentive wakefulness or phasic REM sleep periods

  2. The cholinergic agonist carbachol increases the frequency of spontaneous GABAergic synaptic currents in dorsal raphe serotonergic neurons in the mouse.

    PubMed

    Yang, C; Brown, R E

    2014-01-31

    Dorsal raphe nucleus (DRN) serotonin (5-HT) neurons play an important role in feeding, mood control and stress responses. One important feature of their activity across the sleep-wake cycle is their reduced firing during rapid-eye-movement (REM) sleep which stands in stark contrast to the wake/REM-on discharge pattern of brainstem cholinergic neurons. A prominent model of REM sleep control posits a reciprocal interaction between these cell groups. 5-HT inhibits cholinergic neurons, and activation of nicotinic receptors can excite DRN 5-HT neurons but the cholinergic effect on inhibitory inputs is incompletely understood. Here, in vitro, in DRN brain slices prepared from GAD67-GFP knock-in mice, a brief (3 min) bath application of carbachol (50 μM) increased the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) in GFP-negative, putative 5-HT neurons but did not affect miniature (tetrodotoxin-insensitive) IPSCs. Carbachol had no direct postsynaptic effect. Thus, carbachol likely increases the activity of local GABAergic neurons which synapse on 5-HT neurons. Removal of dorsal regions of the slice including the ventrolateral periaqueductal gray (vlPAG) region where GABAergic neurons projecting to the DRN have been identified, abolished the effect of carbachol on sIPSCs whereas the removal of ventral regions containing the oral region of the pontine reticular nucleus (PnO) did not. In addition, carbachol directly excited GFP-positive, GABAergic vlPAG neurons. Antagonism of both muscarinic and nicotinic receptors completely abolished the effects of carbachol. We suggest cholinergic neurons inhibit DRN 5-HT neurons when acetylcholine levels are lower i.e. during quiet wakefulness and the beginning of REM sleep periods, in part via excitation of muscarinic and nicotinic receptors located on local vlPAG and DRN GABAergic neurons. Higher firing rates or burst firing of cholinergic neurons associated with attentive wakefulness or phasic REM sleep periods

  3. The novel β3-adrenoceptor agonist mirabegron reduces carbachol-induced contractile activity in detrusor tissue from patients with bladder outflow obstruction with or without detrusor overactivity.

    PubMed

    Svalø, Julie; Nordling, Jørgen; Bouchelouche, Kirsten; Andersson, Karl-Erik; Korstanje, Cees; Bouchelouche, Pierre

    2013-01-15

    β(3)-Adrenoceptors are major players in detrusor relaxation and have been suggested as a new putative target for the treatment of overactive bladder syndrome. We determined the effects of mirabegron (YM178), a novel β(3)-adrenoceptor agonist, on carbachol-induced tone in isolated human detrusor preparations from patients with bladder outflow obstruction (BOO) with and without detrusor overactivity (DO), and from patients with normal bladder function. We compared the effects to those of isoprenaline, a non-selective β-adrenoceptor agonist. Detrusor specimens were obtained from patients with benign prostatic hyperplasia undergoing cystoscopy and from patients undergoing radical prostatectomy/cystectomy (in total 33 donors). Detrusor contractility was evaluated by organ bath studies and strips were incubated with carbachol (1μM) to induce and enhance tension. Both mirabegron and isoprenaline reduced carbachol-induced tone in tissues from all groups. Isoprenaline decreased tension with higher potency than mirabegron in normal, BOO and BOO+DO detrusor strips with pIC(50) values of 7.49 ± 0.16 vs. 6.23 ± 0.26 (P=0.0002), 6.89 ± 0.34 vs. 6.04 ± 0.31 (P=0.01), and 6.57 ± 0.20 vs. 5.41 ± 0.08 (P<0.0001, n=4), respectively. The maximal relaxant effect of isoprenaline and mirabegron in the normal, BOO and BOO+DO detrusor was 37.7 ± 14.4% and 36.1 ± 23.3%, 14.4 ± 12.2% vs. 33.4 ± 21.0% and 18.3 ± 10.0% vs. 28.3 ± 12.2% (n=4, P>0.05), respectively. Mirabegron and isoprenaline reduced carbachol-induced tone in both normal bladders and obstructed bladder with and without DO. Isoprenaline had higher potency than mirabegron, but the efficacy of mirabegron effect was the same as that of isoprenaline. PMID:23246623

  4. Increase in sensitivity of the baroreceptor reflex following microinjection of carbachol into the posterior hypothalamic nucleus of awake rats.

    PubMed

    Newey, C R; Martin, J R

    2016-01-01

    In a rat model, the baroreceptor reflex can be assessed by graded infusions of either phenylephrine or sodium nitroprusside with continuous hemodynamic monitoring. Microinjection of the cholinergic agonist carbachol (CCh) into the posterior hypothalamic nucleus (PHN) evokes an increase in mean arterial pressure and a change in heart rate. Lower doses of CCh evoke only tachycardia, whereas middle and higher doses evoke a biphasic change in heart rate of tachycardia followed by bradycardia. The bradycardia following the microinjection of CCh into the PHN can be attenuated by the previous administration of the vasopressin V1 receptor antagonist [d(CH2 )5 Tyr(Me)] arginine vasopressin (AVPX). Circulating arginine vasopressin (AVP) has been shown to increase the sensitivity of the baroreceptor reflex by stimulating vasopressin V1 receptors in the area postrema. The attenuation by AVPX of the bradycardia that results following the high doses of CCh suggests that AVP is released into the circulation following stimulation of cholinergic systems within the PHN. Thus, microinjection of a high dose of CCh (11 nmol) into the PHN alters the sensitivity of the baroreceptor reflex by increasing peripheral levels of AVP. PMID:27555117

  5. Carbachol and bradykinin elevate cyclic AMP and rapidly deplete ATP in cultured rat sympathetic neurons.

    PubMed Central

    Suidan, H S; Murrell, R D; Tolkovsky, A M

    1991-01-01

    The agonists carbachol (CCh) and bradykinin (BK) and 54 mM KCl (high K+) were among the most potent stimulants of cyclic AMP (cAMP) production in cultured rat sympathetic neurons, measured with the use of a high-fidelity assay developed for small samples. The rise in cAMP evoked by CCh (through muscarinic receptors), BK, and high K+ was inhibited in Ca2(+)-depleted medium (1.3 mM Ca2+ and 2 mM BAPTA or EGTA), which also prevented the sustained rise in [Ca2+]i evoked by each of these stimuli, showing that elevation of cAMP requires extracellular Ca2+ and, possibly, Ca2+ influx. Preliminary results obtained with the novel calmodulin inhibitor CGS 9343B, which blocked the elevation of cAMP, and with the cyclogenase inhibitor indomethacin, which partially blocked the actions of the agonists but not those of high K+, suggest that calmodulin and arachidonate metabolites may be two components of the signaling pathway. In addition to their effects on cAMP metabolism, CCh, muscarine, and BK, but not nicotine, caused a 30-40% decrease in ATP levels. This effect was much greater than that evoked by high K+ and was largely inhibited by CGS 9343B but slightly enhanced in the Ca(+)-depleted medium, showing that agonists are still active in the absence of [Ca2+]o. Thus, agonists that activate phosphoinositide metabolism can also increase cAMP production and substantially deplete cells of ATP. These novel actions may have to be taken into account when the mechanisms by which such agonists regulate cell function are being considered. PMID:1848792

  6. The hypothermic action of carbachol in the rat brain periaqueductal grey area may involve neurotensin.

    PubMed Central

    Griffiths, E. C.; Slater, P.; Widdowson, P. S.

    1986-01-01

    Neurotensin (NT) and carbachol both caused hypothermia when injected into the periaqueductal grey area (PAG) of rat brain. Atropine prevented carbachol- but not NT-induced hypothermia. NT-induced hypothermia was unaffected by various neurotransmitter agonists and antagonists in the PAG. Both NT antibodies and thyrotrophin releasing hormone prevented carbachol hypothermia. It is concluded that the hypothermic action of carbachol in the PAG is mediated via endogenous NT. PMID:3742153

  7. Role of phosphatidic acid in carbachol-induced contraction in guinea pig Taenia coli.

    PubMed

    Ohata, H; Nobe, K; Momose, K

    1991-01-01

    Carbachol (CCh, 10(-8)-10(-4) M) increased in concentration-dependent manner the mass of phosphatidic acid (PA), but not the mass of diacylglycerol (DG) in the Taenia coli from guinea pig. The increase in the amount of PA caused by CCh was maintained for 20 min. Release of choline from choline phospholipids labeled with [methyl-3H]choline was not changed by CCh. A DG kinase inhibitor, R59022, inhibited the CCh-induced increase in the mass of PA. These results indicate that the increase in the mass of PA by CCh is due to immediate phosphorylation by DG kinase to PA, of the DG produced by phospholipase C (PLC). It is not due to formation of PA by the direct action of phospholipase D. CCh increased 45Ca2+ uptake into the tissue. R59022 inhibited the sustained phase of CCh-induced contraction and 45Ca2+ uptake into the tissue, but only slightly inhibited the initial phase of the CCh-induced contraction. This inhibition by R59022 may result from the inhibitory effect on the CCh-induced increase in PA. These results suggest that CCh activates both PLC and DG kinase and the resultant increase in the mass of PA contributes to the regulation of the sustained phase of CCh-induced contraction which is related to Ca2+ influx.

  8. Carbachol models of REM sleep: recent developments and new directions.

    PubMed

    Kubin, L

    2001-02-01

    Since the early '60s, injections of a broad-spectrum muscarinic cholinergic agonist, carbachol, into the medial pontine reticular formation (mPRF) of cats have been extensively used as a tool with which to study the neural mechanisms of rapid eye movement (REM) sleep. During the last decade, new carbachol models of REM sleep were introduced, including chronically instrumented/behaving rats and "reduced" preparations such as decerebrate or anesthetized cats and rats. The combined results from these distinct models show interspecies similarities and differences. The dual nature, both REM sleep-promoting and wakefulness (or arousal)-promoting, of the cholinergic effects exerted within the mPRF is more strongly expressed in rats than in cats. This strengthens the possibility suggested by earlier central neuronal recordings that active wakefulness and REM sleep have extensive common neuronal substrates, and may have evolved from a common behavioral state. Carbachol studies using different intact and reduced models also suggest that powerful REM sleep episode-terminating effects originate in suprapontine structures. In contrast, the timing of REM sleep-like episodes in decerebrate models is determined by a pontomedullary neuronal network responsible for the generation of an ultradian cycle similar to the basic rest-activity cycle of N. Kleitman. Other presumed species differences, such as the more widespread distribution of carbachol-sensitive sites or the relative failure of carbachol to increase the duration of REM sleep episodes in rats when compared to cats, may be of a quantitative or technical nature. While carbachol and many other neurotransmitters and peptides microinjected into the mPRF evoke, enhance or suppress REM sleep, the most sensitive site(s) of their actions have not been fully mapped, and the nature of the cellular and neurochemical interactions taking place at the sites where carbachol triggers the REM sleep-like state remain largely unknown

  9. Denatonium and 6-n-Propyl-2-thiouracil, Agonists of Bitter Taste Receptor, Inhibit Contraction of Various Types of Smooth Muscles in the Rat and Mouse.

    PubMed

    Sakai, Hiroyasu; Sato, Ken; Kai, Yuki; Chiba, Yoshihiko; Narita, Minoru

    2016-01-01

    Recently the global expression of taste 2 receptors (TAS2Rs) on smooth muscle cells in human airways was demonstrated. Here, the effects of agonists of taste receptor, type 2, denatonium and 6-n-propyl-2-thiouracil, on smooth-muscle contraction were examined in the rat and mouse. Contractions induced by carbachol (CCh), high K(+), and sodium fluoride, but not calyculin-A, were inhibited significantly in the presence of a TAS2R agonist in the bronchial smooth muscle of mice. The contraction induced by CCh was inhibited by TAS2R agonists in ileal smooth muscle. Phenylephrine-induced contraction was also inhibited by TAS2R agonists in aortic smooth muscle. Gastrointestinal motility and blood pressure were attenuated by administration of TAS2R agonists in vivo. These findings suggest that TAS2R may be receptor for endogenous biologically active substances as well as for bitter tastes on the tongue. TAS2R signaling could be employed in the development of anti-asthmatic, anti-spasmodic, and anti-hypertensive drugs.

  10. Denatonium and 6-n-Propyl-2-thiouracil, Agonists of Bitter Taste Receptor, Inhibit Contraction of Various Types of Smooth Muscles in the Rat and Mouse.

    PubMed

    Sakai, Hiroyasu; Sato, Ken; Kai, Yuki; Chiba, Yoshihiko; Narita, Minoru

    2016-01-01

    Recently the global expression of taste 2 receptors (TAS2Rs) on smooth muscle cells in human airways was demonstrated. Here, the effects of agonists of taste receptor, type 2, denatonium and 6-n-propyl-2-thiouracil, on smooth-muscle contraction were examined in the rat and mouse. Contractions induced by carbachol (CCh), high K, and sodium fluoride, but not calyculin-A, were inhibited significantly in the presence of a TAS2R agonist in the bronchial smooth muscle of mice. The contraction induced by CCh was inhibited by TAS2R agonists in ileal smooth muscle. Phenylephrine-induced contraction was also inhibited by TAS2R agonists in aortic smooth muscle. Gastrointestinal motility and blood pressure were attenuated by administration of TAS2R agonists in vivo. These findings suggest that TAS2R may be receptor for endogenous biologically active substances as well as for bitter tastes on the tongue. TAS2R signaling could be employed in the development of anti-asthmatic, anti-spasmodic, and anti-hypertensive drugs. PMID:27110632

  11. Denatonium and 6-n-Propyl-2-thiouracil, Agonists of Bitter Taste Receptor, Inhibit Contraction of Various Types of Smooth Muscles in the Rat and Mouse.

    PubMed

    Sakai, Hiroyasu; Sato, Ken; Kai, Yuki; Chiba, Yoshihiko; Narita, Minoru

    2016-01-01

    Recently the global expression of taste 2 receptors (TAS2Rs) on smooth muscle cells in human airways was demonstrated. Here, the effects of agonists of taste receptor, type 2, denatonium and 6-n-propyl-2-thiouracil, on smooth-muscle contraction were examined in the rat and mouse. Contractions induced by carbachol (CCh), high K(+), and sodium fluoride, but not calyculin-A, were inhibited significantly in the presence of a TAS2R agonist in the bronchial smooth muscle of mice. The contraction induced by CCh was inhibited by TAS2R agonists in ileal smooth muscle. Phenylephrine-induced contraction was also inhibited by TAS2R agonists in aortic smooth muscle. Gastrointestinal motility and blood pressure were attenuated by administration of TAS2R agonists in vivo. These findings suggest that TAS2R may be receptor for endogenous biologically active substances as well as for bitter tastes on the tongue. TAS2R signaling could be employed in the development of anti-asthmatic, anti-spasmodic, and anti-hypertensive drugs. PMID:26567724

  12. Nipecotic acid ethyl ester: a cholinergic agonist that may differentiate muscarinic receptor subtypes

    SciTech Connect

    Zorn, S.H.; Duman, R.S.; Enna, S.J.; Krogsgaard-Larsen, P.; Micheletti, R.; Giraldo, E.; Giachetti, A.

    1986-03-05

    Reports indicate that nipecotic acid ethyl ester (NAEE) displays cholinomimetic properties in vivo. In the present study a series of physiological and biochemical tests were conducted to characterize this action. NAEE had a negative inotropic effect on the guinea pig atrium, and stimulated contraction of the guinea pig ileum and isolated mouse stomach strip at concentrations similar to bethanechol (BCH). The atrial and ilial effects were reversed by atropine. Unlike BCH, NAEE had no effect on basal acid secretion in the isolated mouse stomach at concentrations < 100 ..mu..M. NAEE was more potent than carbachol (CCH) in displacing /sup 3/H-ONB binding from rat brain membranes. The potency of NAEE to inhibit antagonist binding in rat heart membranes was enhanced by Mg/sup + +/ (Hill coefficient < 1.0) and reduced by Gpp(NH)p. Like CCH, NAEE inhibited GTP-stimulated adenylate cyclase in rat brain striatal membranes. As compared to CCH, NAEE had little effect (< 5%) as a stimulator of inositol phosphate (IP) production in rat brain slices. The results indicate that NAEE is a direct-acting muscarinic receptor agonist. Moreover, its differential effects on acid secretion, IP accumulation, and adenylate cyclase suggest that it may be useful for defining cholinergic receptor subclasses.

  13. Carbachol ameliorates lipopolysaccharide-induced intestinal epithelial tight junction damage by down-regulating NF-{kappa}{beta} and myosin light-chain kinase pathways

    SciTech Connect

    Zhang, Ying; Li, Jianguo

    2012-11-16

    Highlights: Black-Right-Pointing-Pointer Carbachol reduced the lipopolysaccharide-induced intestinal barrier breakdown. Black-Right-Pointing-Pointer Carbachol ameliorated the lipopolysaccharide-induced ileal tight junction damage. Black-Right-Pointing-Pointer Carbachol prevented the LPS-induced NF-{kappa}{beta} and myosin light-chain kinase activation. Black-Right-Pointing-Pointer Carbachol exerted its beneficial effects in an {alpha}7 nicotinic receptor-dependent manner. -- Abstract: Carbachol is a cholinergic agonist that protects the intestines after trauma or burn injury. The present study determines the beneficial effects of carbachol and the mechanisms by which it ameliorates the lipopolysaccharide (LPS)-induced intestinal barrier breakdown. Rats were injected intraperitoneally with 10 mg/kg LPS. Results showed that the gut barrier permeability was reduced, the ultrastructural disruption of tight junctions (TJs) was prevented, the redistribution of zonula occludens-1 and claudin-2 proteins was partially reversed, and the nuclear factor-kappa beta (NF-{kappa}{beta}) and myosin light-chain kinase (MLCK) activation in the intestinal epithelium were suppressed after carbachol administration in LPS-exposed rats. Pretreatment with the {alpha}7 nicotinic acetylcholine receptor ({alpha}7nAchR) antagonist {alpha}-bungarotoxin blocked the protective action of carbachol. These results suggested that carbachol treatment can protect LPS-induced intestinal barrier dysfunction. Carbachol exerts its beneficial effect on the amelioration of the TJ damage by inhibiting the NF-{kappa}{beta} and MLCK pathways in an {alpha}7nAchR-dependent manner.

  14. Contribution of Ih to the relative facilitation of synaptic responses induced by carbachol in the entorhinal cortex during repetitive stimulation of the parasubiculum.

    PubMed

    Sparks, D W; Chapman, C A

    2014-10-10

    Neurons in the superficial layers of the entorhinal cortex provide the hippocampus with the majority of its cortical sensory input, and also receive the major output projection from the parasubiculum. This puts the parasubiculum in a position to modulate the activity of entorhinal neurons that project to the hippocampus. These brain areas receive cholinergic projections that are active during periods of theta- and gamma-frequency electroencephalographic (EEG) activity. The purpose of this study was to investigate how cholinergic receptor activation affects the strength of repetitive synaptic responses at these frequencies in the parasubiculo-entorhinal pathway and the cellular mechanisms involved. Whole-cell patch-clamp recordings of rat layer II medial entorhinal neurons were conducted using an acute slice preparation, and responses to 5-pulse trains of stimulation at theta- and gamma-frequency delivered to the parasubiculum were recorded. The cholinergic agonist carbachol (CCh) suppressed the amplitude of single synaptic responses, but also produced a relative facilitation of synaptic responses evoked during stimulation trains. The N-methyl-d-aspartate (NMDA) glutamate receptor blocker APV did not significantly reduce the relative facilitation effect. However, the hyperpolarization-activated cationic current (Ih) channel blocker ZD7288 mimicked the relative facilitation induced by CCh, suggesting that CCh-induced inhibition of Ih could produce the effect by increasing dendritic input resistance (Rin). Inward-rectifying and leak K(+) currents are known to interact with Ih to affect synaptic excitability. Application of the K(+) channel antagonist Ba(2+) depolarized neurons and enhanced temporal summation, but did not block further facilitation of train-evoked responses by ZD7288. The Ih-dependent facilitation of synaptic responses can therefore occur during reductions in inward-rectifying potassium current (IKir) associated with dendritic depolarization. Thus, in

  15. Carbachol dimers as homobivalent modulators of muscarinic receptors.

    PubMed

    Matucci, Rosanna; Nesi, Marta; Martino, Maria Vittoria; Bellucci, Cristina; Manetti, Dina; Ciuti, Elisa; Mazzolari, Angelica; Dei, Silvia; Guandalini, Luca; Teodori, Elisabetta; Vistoli, Giulio; Romanelli, Maria Novella

    2016-05-15

    A series of homodimers of the well-known cholinergic agonist carbachol have been synthesized, showing the two agonist units symmetrically connected through a methylene chain of variable length. The new compounds have been tested on the five cloned muscarinic receptors (hM1-5) expressed in CHO cells by means of equilibrium binding studies, showing an increase in affinity by rising the number of methylene units up to 7 and 9. Functional experiments on guinea-pig ileum and assessment of ERK1/2 phosphorylation on hM1, hM2 and hM3 on CHO cells have shown that the new compounds are endowed with muscarinic antagonistic properties. Kinetic binding studies have revealed that some of the tested compounds are able to slow the rate of dissociation of NMS, suggesting a bitopic behavior. Docking simulations, performed on the hM1 and hM2 receptors, give a sound rationalization of the experimental data revealing how these compounds are able to interact with both orthosteric and allosteric binding sites depending on the length of their connecting chain. PMID:26996304

  16. Motoneuron properties during motor inhibition produced by microinjection of carbachol into the pontine reticular formation of the decerebrate cat.

    PubMed

    Morales, F R; Engelhardt, J K; Soja, P J; Pereda, A E; Chase, M H

    1987-04-01

    It is well established that cholinergic agonists, when injected into the pontine reticular formation in cats, produce a generalized suppression of motor activity (1, 3, 6, 14, 18, 27, 33, 50). The responsible neuronal mechanisms were explored by measuring ventral root activity, the amplitude of the Ia-monosynaptic reflex, and the basic electrophysiological properties of hindlimb motoneurons before and after carbachol was microinjected into the pontine reticular formation of decerebrate cats. Intrapontine microinjections of carbachol (0.25-1.0 microliter, 16 mg/ml) resulted in the tonic suppression of ventral root activity and a decrease in the amplitude of the Ia-monosynaptic reflex. An analysis of intracellular records from lumbar motoneurons during the suppression of motor activity induced by carbachol revealed a considerable decrease in input resistance and membrane time constant as well as a reduction in motoneuron excitability, as evidenced by a nearly twofold increase in rheobase. Discrete inhibitory postsynaptic potentials were also observed following carbachol administration. The changes in motoneuron properties (rheobase, input resistance, and membrane time constant), as well as the development of discrete inhibitory postsynaptic potentials, indicate that spinal cord motoneurons were postsynaptically inhibited following the pontine administration of carbachol. In addition, the inhibitory processes that arose after carbachol administration in the decerebrate cat were remarkably similar to those that are present during active sleep in the chronic cat. These findings suggest that the microinjection of carbachol into the pontine reticular formation activates the same brain stem-spinal cord system that is responsible for the postsynaptic inhibition of alpha-motoneurons that occurs during active sleep. PMID:3585456

  17. Mechanisms involved in carbachol-induced Ca2+ sensitization of contractile elements in rat proximal and distal colon

    PubMed Central

    Takeuchi, Tadayoshi; Kushida, Masahiko; Hirayama, Nobue; Kitayama, Muneyoshi; Fujita, Akikazu; Hata, Fumiaki

    2004-01-01

    Mechanisms involved in Ca2+ sensitization of contractile elements induced by the activation of muscarinic receptors in membrane-permeabilized preparations of the rat proximal and distal colon were studied. In α-toxin-permeabilized preparations from the rat proximal and distal colon, Ca2+ induced a rapid phasic and subsequent tonic component. After Ca2+-induced contraction reached a plateau, guanosine 5′-triphosphate (GTP) and carbachol (CCh) in the presence of GTP further contracted preparations of both the proximal and distal colon (Ca2+ sensitization). Y-27632, a rho-kinase inhibitor, inhibited GTP plus CCh-induced Ca2+ sensitization more significantly in the proximal colon than in the distal colon. Y-27632 at 10 μM had no effect on Ca2+-induced contraction or slightly inhibited phorbol-12,13-dibutyrate-induced Ca2+ sensitization in either proximal or distal colon. Chelerythrine, a protein kinase C inhibitor, inhibited GTP plus CCh-induced Ca2+ sensitization in the distal colon, but not in the proximal colon. The component of Ca2+ sensitization that persisted after the chelerythrine treatment was completely inhibited by Y-27632. In β-escin-permeabilized preparations of the proximal colon, C3 exoenzyme completely inhibited GTP plus CCh-induced Ca2+ sensitization, but PKC(19–31) did not. In the distal colon, C3 exoenzyme abolished GTP-induced Ca2+ sensitization. It inhibited CCh-induced sensitization by 50 % and the remaining component was inhibited by PKC(19–31). These results suggest that both protein kinase C and rho pathways in parallel mediate the Ca2+ sensitization coupled to activation of muscarinic receptors in the rat distal colon, whereas the rho pathway alone mediates this action in the proximal colon. PMID:15159278

  18. Carbachol-Induced Reduction in the Activity of Adult Male Zebra Finch RA Projection Neurons.

    PubMed

    Meng, Wei; Wang, Song-Hua; Li, Dong-Feng

    2016-01-01

    Cholinergic mechanism is involved in motor behavior. In songbirds, the robust nucleus of the arcopallium (RA) is a song premotor nucleus in the pallium and receives cholinergic inputs from the basal forebrain. The activity of projection neurons in RA determines song motor behavior. Although many evidences suggest that cholinergic system is implicated in song production, the cholinergic modulation of RA is not clear until now. In the present study, the electrophysiological effects of carbachol, a nonselective cholinergic receptor agonist, were investigated on the RA projection neurons of adult male zebra finches through whole-cell patch-clamp techniques in vitro. Our results show that carbachol produced a significant decrease in the spontaneous and evoked action potential (AP) firing frequency of RA projection neurons, accompanying a hyperpolarization of the membrane potential, an increase in the evoked AP latency, afterhyperpolarization (AHP) peak amplitude, and AHP time to peak, and a decrease in the membrane input resistance, membrane time constant, and membrane capacitance. These results indicate that carbachol reduces the activity of RA projection neurons by hyperpolarizing the resting membrane potential and increasing the AHP and the membrane conductance, suggesting that the cholinergic modulation of RA may play an important role in song production. PMID:26904300

  19. The Role of Rac1 on Carbachol-induced Contractile Activity in Detrusor Smooth Muscle from Streptozotocin-induced Diabetic Rats.

    PubMed

    Evcim, Atiye Sinem; Micili, Serap Cilaker; Karaman, Meral; Erbil, Guven; Guneli, Ensari; Gidener, Sedef; Gumustekin, Mukaddes

    2015-06-01

    This study was designed to determine the role of the small GTPase Rac1 on carbachol-induced contractile activity in detrusor smooth muscle using small inhibitor NSC 23766 in diabetic rats. Rac1 expression in bladder tissue was also evaluated. In the streptozotocin (STZ)-induced diabetic rat model, three study groups were composed of control, diabetic and insulin-treated diabetic subjects. The detrusor muscle strips were suspended in organ baths at the end of 8-12 weeks after STZ injection. Carbachol (CCh) (10(-9) -10(-4) M) concentration-response curves were obtained both in the absence and in the presence of Rac1 inhibitor NSC 23766 (0.1, 1 and 10 μM). Diabetes-related histopathological changes and Rac1 expressions were assessed by haematoxylin and eosin staining and immunohistochemical staining, respectively. CCh caused dose-dependent contractile responses in all the study groups. Rac1 inhibitor NSC 23766 inhibited CCh-induced contractile responses in all groups, but this inhibition seen in both diabetes groups was greater than in the control group. Histological examination revealed an increased bladder wall thickness both in the diabetes and in the insulin-treated diabetes groups compared to the control group. In immunohistochemical staining, expression of Rac1 was observed to be increased in all layers of bladder in both diabetic groups compared to the control group. In the diabetic bladders, increased expression of Rac1 and considerable inhibition of CCh-induced responses in the presence of NSC 23766 compared to those of the control group may indicate a specific role of Rac1 in diabetes-related bladder dysfunction, especially associated with cholinergic mediated detrusor overactivity.

  20. Abundance anomaly of the 13C species of CCH

    NASA Astrophysics Data System (ADS)

    Sakai, N.; Saruwatari, O.; Sakai, T.; Takano, S.; Yamamoto, S.

    2010-03-01

    Aims: We have observed the N = 1-0 lines of CCH and its 13C isotopic species toward a cold dark cloud, TMC-1 and a star-forming region, L1527, to investigate the 13C abundances and formation pathways of CCH. Methods: The observations have been carried out with the IRAM 30 m telescope. Results: We have successfully detected the lines of 13CCH and C13CH toward the both sources and found a significant intensity difference between the two 13C isotopic species. The [C13CH] /[13CCH] abundance ratios are 1.6 ± 0.4 (3σ) and 1.6 ± 0.1 (3σ) for TMC-1 and L1527, respectively. The abundance difference between C13CH and 13CCH means that the two carbon atoms of CCH are not equivalent in the formation pathway. On the other hand, the [CCH]/[C13CH] and [CCH]/[13CCH] ratios are evaluated to be larger than 170 and 250 toward TMC-1, and to be larger than 80 and 135 toward L1527, respectively. Therefore, both of the 13C species are significantly diluted in comparison with the interstellar 12C/13C ratio of 60. The dilution is discussed in terms of a behavior of 13C in molecular clouds.

  1. Growling component of vocalization as a quantitative index of carbachol-induced emotional-defensive response in cats.

    PubMed

    Brudzyński, S M

    1981-01-01

    Vocalization and eye movements during emotional-defensive response evoked by unilateral intrahypothalamic carbachol injections (10 micrograms) were quantitatively determined. The growling episodes duration paralleled the development and the subsiding of the defensive behavior, while the changes of eye movements indicated rather a general arousal than the course of agonistic attitude. The growling component can be treated as (i) a specific form of vocalization for emotional-defensive response, (ii) quantitative intensity index of the response, and (iii) a value reflecting the dynamics and the time-course of the emotional state, unlike the hissing component which is inappropriate for quantitative determination. The results enable to treat the carbachol-induced response as a model for quantitative investigations on emotional-defensive states in cats. The vocalization changes compared with cardiovascular changes are discussed in terms of their usefulness in measurements of aversive emotional responses. PMID:7196680

  2. Cholinergic agonists transactivate EGFR and stimulate MAPK to induce goblet cell secretion.

    PubMed

    Kanno, Harumi; Horikawa, Yoshitaka; Hodges, Robin R; Zoukhri, Driss; Shatos, Marie A; Rios, Jose D; Dartt, Darlene A

    2003-04-01

    Conjunctival goblet cells are the primary source of mucins in the mucous layer, the innermost layer of the tear film. Conjunctival goblet cell mucin secretion is under neural control because exogenous addition of parasympathetic agonists stimulates goblet cell secretion. To elucidate the intracellular signal pathways used by cholinergic agonists to stimulate goblet cell mucin secretion, we determined whether p42/p44 mitogen-activated protein kinase (MAPK) is activated during cholinergic agonist-stimulated mucin secretion. Rat conjunctiva was removed, preincubated with or without antagonists, and stimulated with the cholinergic agonist carbachol (10(-4) M). Carbachol statistically significantly stimulated the phosphorylation of MAPK in a time- and concentration-dependent manner. U-0126, an inhibitor of MAPK activation, completely inhibited both the activation of MAPK and goblet cell secretion stimulated by carbachol. The M(1) muscarinic antagonist pirenzepine, the M(2) muscarinic antagonist gallamine, and the M(1)/M(3) muscarinic receptor antagonist N-(3-chloropropyl)-4-piperidinyl diphenylacetate (4-DAMP) also inhibited carbachol-stimulated MAPK activation. Increasing the intracellular Ca(2+) concentration with a Ca(2+) ionophore increased MAPK activation, and chelation of extracellular Ca(2+) inhibited carbachol-stimulated activation. Carbachol also increased tyrosine phosphorylation of Pyk2, p60Src, and the epidermal growth factor receptor (EGFR). The Src inhibitor PP1 and the EGFR inhibitor AG-1478 completely inhibited carbachol-stimulated MAPK activation. AG-1478 also inhibited goblet cell secretion. We conclude that carbachol transactivates the EGFR to activate MAPK, leading to conjunctival goblet cell secretion. In addition, carbachol also activates Pyk2 and p60Src that could play a role in the transactivation of the EGFR.

  3. Neocortical 40 Hz oscillations during carbachol-induced rapid eye movement sleep and cataplexy.

    PubMed

    Torterolo, Pablo; Castro-Zaballa, Santiago; Cavelli, Matías; Chase, Michael H; Falconi, Atilio

    2016-02-01

    Higher cognitive functions require the integration and coordination of large populations of neurons in cortical and subcortical regions. Oscillations in the gamma band (30-45 Hz) of the electroencephalogram (EEG) have been involved in these cognitive functions. In previous studies, we analysed the extent of functional connectivity between cortical areas employing the 'mean squared coherence' analysis of the EEG gamma band. We demonstrated that gamma coherence is maximal during alert wakefulness and is almost absent during rapid eye movement (REM) sleep. The nucleus pontis oralis (NPO) is critical for REM sleep generation. The NPO is considered to exert executive control over the initiation and maintenance of REM sleep. In the cat, depending on the previous state of the animal, a single microinjection of carbachol (a cholinergic agonist) into the NPO can produce either REM sleep [REM sleep induced by carbachol (REMc)] or a waking state with muscle atonia, i.e. cataplexy [cataplexy induced by carbachol (CA)]. In the present study, in cats that were implanted with electrodes in different cortical areas to record polysomnographic activity, we compared the degree of gamma (30-45 Hz) coherence during REMc, CA and naturally-occurring behavioural states. Gamma coherence was maximal during CA and alert wakefulness. In contrast, gamma coherence was almost absent during REMc as in naturally-occurring REM sleep. We conclude that, in spite of the presence of somatic muscle paralysis, there are remarkable differences in cortical activity between REMc and CA, which confirm that EEG gamma (≈40 Hz) coherence is a trait that differentiates wakefulness from REM sleep. PMID:26670051

  4. Neocortical 40 Hz oscillations during carbachol-induced rapid eye movement sleep and cataplexy.

    PubMed

    Torterolo, Pablo; Castro-Zaballa, Santiago; Cavelli, Matías; Chase, Michael H; Falconi, Atilio

    2016-02-01

    Higher cognitive functions require the integration and coordination of large populations of neurons in cortical and subcortical regions. Oscillations in the gamma band (30-45 Hz) of the electroencephalogram (EEG) have been involved in these cognitive functions. In previous studies, we analysed the extent of functional connectivity between cortical areas employing the 'mean squared coherence' analysis of the EEG gamma band. We demonstrated that gamma coherence is maximal during alert wakefulness and is almost absent during rapid eye movement (REM) sleep. The nucleus pontis oralis (NPO) is critical for REM sleep generation. The NPO is considered to exert executive control over the initiation and maintenance of REM sleep. In the cat, depending on the previous state of the animal, a single microinjection of carbachol (a cholinergic agonist) into the NPO can produce either REM sleep [REM sleep induced by carbachol (REMc)] or a waking state with muscle atonia, i.e. cataplexy [cataplexy induced by carbachol (CA)]. In the present study, in cats that were implanted with electrodes in different cortical areas to record polysomnographic activity, we compared the degree of gamma (30-45 Hz) coherence during REMc, CA and naturally-occurring behavioural states. Gamma coherence was maximal during CA and alert wakefulness. In contrast, gamma coherence was almost absent during REMc as in naturally-occurring REM sleep. We conclude that, in spite of the presence of somatic muscle paralysis, there are remarkable differences in cortical activity between REMc and CA, which confirm that EEG gamma (≈40 Hz) coherence is a trait that differentiates wakefulness from REM sleep.

  5. Activation of T84 cell chloride channels by carbachol involves a phosphoinositide-coupled muscarinic M3 receptor.

    PubMed

    Dickinson, K E; Frizzell, R A; Sekar, M C

    1992-04-10

    Muscarinic agonists stimulate Cl- secretion across monolayers of the colon tumor epithelial cell line, T84. The muscarinic receptor has been characterized in T84 cell homogenates by radioligand binding using [3H]N-methylscopolamine ([3H]NMS). [3H]NMS bound to a single population of sites at 25 degrees C in 100 mM NaCl, 20 mM HEPES, 10 mM MgCl2, pH 7.4 buffer, with calculated Kd = 278 (+/- 44) pM and Bmax = 40 (+/- 6) fmol/mg protein (n = 4). Binding was reversible (diss. t1/2 = 18 +/- 3 min) and stereoselective (dexetimide Ki = 0.3 nM) much greater than levetimide (Ki = 8300 nM). Antagonists exhibited the following rank order of potencies and Ki values (nM): atropine (0.54) greater than 4-diphenylacetoxy-N-methylpiperidine methobromide (4-DAMP) (0.84) greater than dicyclomine (14) = hexahydrosiladifenidol (18) greater than pirenzepine (136) greater than AF-DX 116 (3610). The same sequence was observed for inhibition of carbachol-induced 125I efflux from T84 monolayers. This is indicative of an M3 'glandular' muscarinic receptor. Coupling to second messenger systems was examined by labelling monolayers with [14C]arachidonic acid (AA) or [3H]inositol. Carbachol (0.3 mM) did not release [14C]AA from labelled lipids, but ionomycin produced a dose-dependent increase in media [14C]AA. Carbachol (0.3 mM) elevated inositol monophosphate 14-fold. The results suggest that muscarinic agonists stimulate Cl- secretion by interacting with an M3 receptor coupled to inositide lipid hydrolysis. PMID:1379932

  6. Carbon Chemistry in Planetary Nebulae: Observations of the CCH Radical

    NASA Astrophysics Data System (ADS)

    Schmidt, Deborah Rose; Ziurys, Lucy

    2015-08-01

    The presence of infrared (IR) emission features observed in interstellar environments is consistent with models that suggest they are produced by complex organic species containing both aliphatic and aromatic components (Kwok & Zhang 2011). These IR signals change drastically over the course of the AGB, proto-planetary, and planetary nebulae phases, and this dramatic variation is yet to be understood. The radical CCH is a potential tracer of carbon chemistry and its evolution in dying stars. CCH is very common in carbon-rich circumstellar envelopes of AGB stars, and is present in the proto-planetary nebulae. It has also been observed at one position in the very young planetary nebula, NGC 7027 (Hasegawa & Kwok 2001), as well as at one position in the Helix Nebula (Tenenbaum et al. 2009) - a dense clump east of the central white dwarf. In order to further probe the chemistry of carbon, we have initiated a search for CCH in eight PNe previously detected in HCN and HCO+ from a survey conducted by Schmidt and Ziurys, using the telescopes of the Arizona Radio Observatory (ARO). Observations of the N=1→0 transition of CCH at 87 GHz have been conducted using the new ARO 12-m ALMA prototype antenna, while measurements of the N=3→2 transition at 262 GHz are being made with the ARO Sub-Millimeter Telescope (SMT). We also have extended our study in the Helix Nebula. Thus far, CCH has been detected at 8 new positions across the Helix Nebula, and appears to be widespread in this source. The radical has also been identified in K4-47, M3-28, K3-17, and K3-58. These sources represent a range of nebular ages. Additional observations are currently being conducted for CCH in other PNe, as well as abundance analyses. These results will be presented.

  7. PLC-γ directly binds activated c-Src, which is necessary for carbachol-mediated inhibition of NHE3 activity in Caco-2/BBe cells.

    PubMed

    Zachos, Nicholas C; Lee, Luke J; Kovbasnjuk, Olga; Li, Xuhang; Donowitz, Mark

    2013-08-01

    Elevated levels of intracellular Ca(2+) ([Ca(2+)]i) inhibit Na(+)/H(+) exchanger 3 (NHE3) activity in the intact intestine. We previously demonstrated that PLC-γ directly binds NHE3, an interaction that is necessary for [Ca(2+)]i inhibition of NHE3 activity, and that PLC-γ Src homology 2 (SH2) domains may scaffold Ca(2+) signaling proteins necessary for regulation of NHE3 activity. [Ca(2+)]i regulation of NHE3 activity is also c-Src dependent; however, the mechanism by which c-Src is involved is undetermined. We hypothesized that the SH2 domains of PLC-γ might link c-Src to NHE3-containing complexes to mediate [Ca(2+)]i inhibition of NHE3 activity. In Caco-2/BBe cells, carbachol (CCh) decreased NHE3 activity by ∼40%, an effect abolished with the c-Src inhibitor PP2. CCh treatment increased the amount of active c-Src as early as 1 min through increased Y(416) phosphorylation. Coimmunoprecipitation demonstrated that c-Src associated with PLC-γ, but not NHE3, under basal conditions, an interaction that increased rapidly after CCh treatment and occurred before the dissociation of PLC-γ and NHE3 that occurred 10 min after CCh treatment. Finally, direct binding to c-Src only occurred through the PLC-γ SH2 domains, an interaction that was prevented by blocking the PLC-γ SH2 domain. This study demonstrated that c-Src 1) activity is necessary for [Ca(2+)]i inhibition of NHE3 activity, 2) activation occurs rapidly (∼1 min) after CCh treatment, 3) directly binds PLC-γ SH2 domains and associates dynamically with PLC-γ under elevated [Ca(2+)]i conditions, and 4) does not directly bind NHE3. Under elevated [Ca(2+)]i conditions, PLC-γ scaffolds c-Src into NHE3-containing multiprotein complexes before dissociation of PLC-γ from NHE3 and subsequent endocytosis of NHE3.

  8. AB Initio Characterization of MgCCH, MgCCH(+), and MgC2, and Pathways to their Formation in the Interstellar Medium

    NASA Technical Reports Server (NTRS)

    Woon, David E.

    1996-01-01

    A study of Mg-bearing compounds has been performed in order to determine molecular properties which are critical for planning new astronomical searches and laboratory studies. The primary focus of the work is on MgCCH, MgCCH(+), and the isomers of MgC2. Only MgCCH has been identified in laboratory studies. Additional calculations have been carried out on MgH, MgNC, MgCN, and their cations in an effort to evaluate pathways to the formation of MgCCH and MgCCH(+) in the InterStellar Medium (ISM) or in circumstellar envelopes. Correlated ab initio methods and correlation-consistent basis sets have been employed. Properties including structures, rotational constants, dipole moments, and harmonic frequencies are reported. A transition state between linear MgCC and cyclic MgC2 has been characterized and was found to yield a minimal barrier (approx. 0.5 kcal/mole), indicating easy interconversion to the cyclic form. Direct reactions in the ISM between Mg or Mg(+) and HCCH are precluded by energetic considerations, but a number of ion- molecule or neutral-neutral exchange reactions between CCH and various Mg-containing species offer plausible pathways to MgCCH or MgCCH(+). Weakly bound MgH may react with CCH to form MgCCH, but MgH has not been detected. Both MgNC and MgCN have been observed, but reactions with CCH are slightly endothermic by 1-3 kcal/mole. Although MgH(+), MgNC(+), and MgCN(+) have not been detected, their reactions with CCH to form MgCCH(+) are all exothermic. With only a small barrier separating linear MgCC and cyclic MgC2, the dissociative recombination of MgCCH(+) with an electron is expected to yield cyclic MgC2, and regenerate Mg and CCH. New astronomical searches for MgCCH, MgCCH(+), cyclic MgC2, MgNC(+), and MgCN(+) will provide further insight into organo-magnesium astrochemistry.

  9. Heart rate variability during carbachol-induced REM sleep and cataplexy.

    PubMed

    Torterolo, Pablo; Castro-Zaballa, Santiago; Cavelli, Matías; Velasquez, Noelia; Brando, Victoria; Falconi, Atilio; Chase, Michael H; Migliaro, Eduardo R

    2015-09-15

    The nucleus pontis oralis (NPO) exerts an executive control over REM sleep. Cholinergic input to the NPO is critical for REM sleep generation. In the cat, a single microinjection of carbachol (a cholinergic agonist) into the NPO produces either REM sleep (REMc) or wakefulness with muscle atonia (cataplexy, CA). In order to study the central control of the heart rate variability (HRV) during sleep, we conducted polysomnographic and electrocardiogram recordings from chronically prepared cats during REMc, CA as well as during sleep and wakefulness. Subsequently, we performed statistical and spectral analyses of the HRV. The heart rate was greater during CA compared to REMc, NREM or REM sleep. Spectral analysis revealed that the low frequency band (LF) power was significantly higher during REM sleep in comparison to REMc and CA. Furthermore, we found that during CA there was a decrease in coupling between the RR intervals plot (tachogram) and respiratory activity. In contrast, compared to natural behavioral states, during REMc and CA there were no significant differences in the HRV based upon the standard deviation of normal RR intervals (SDNN) and the mean squared difference of successive intervals (rMSSD). In conclusion, there were differences in the HRV during naturally-occurring REM sleep compared to REMc. In addition, in spite of the same muscle atonia, the HRV was different during REMc and CA. Therefore, the neuronal network that controls the HRV during REM sleep can be dissociated from the one that generates the muscle atonia during this state. PMID:25997581

  10. Heart rate variability during carbachol-induced REM sleep and cataplexy.

    PubMed

    Torterolo, Pablo; Castro-Zaballa, Santiago; Cavelli, Matías; Velasquez, Noelia; Brando, Victoria; Falconi, Atilio; Chase, Michael H; Migliaro, Eduardo R

    2015-09-15

    The nucleus pontis oralis (NPO) exerts an executive control over REM sleep. Cholinergic input to the NPO is critical for REM sleep generation. In the cat, a single microinjection of carbachol (a cholinergic agonist) into the NPO produces either REM sleep (REMc) or wakefulness with muscle atonia (cataplexy, CA). In order to study the central control of the heart rate variability (HRV) during sleep, we conducted polysomnographic and electrocardiogram recordings from chronically prepared cats during REMc, CA as well as during sleep and wakefulness. Subsequently, we performed statistical and spectral analyses of the HRV. The heart rate was greater during CA compared to REMc, NREM or REM sleep. Spectral analysis revealed that the low frequency band (LF) power was significantly higher during REM sleep in comparison to REMc and CA. Furthermore, we found that during CA there was a decrease in coupling between the RR intervals plot (tachogram) and respiratory activity. In contrast, compared to natural behavioral states, during REMc and CA there were no significant differences in the HRV based upon the standard deviation of normal RR intervals (SDNN) and the mean squared difference of successive intervals (rMSSD). In conclusion, there were differences in the HRV during naturally-occurring REM sleep compared to REMc. In addition, in spite of the same muscle atonia, the HRV was different during REMc and CA. Therefore, the neuronal network that controls the HRV during REM sleep can be dissociated from the one that generates the muscle atonia during this state.

  11. Effect of hydration on the organo-noble gas molecule HKrCCH: role of krypton in the stabilization of hydrated HKrCCH complexes.

    PubMed

    Biswas, Biswajit; Singh, Prashant Chandra

    2015-11-11

    The effect of hydration on the fluorine free organo-noble gas compound HKrCCH and the role of krypton in the stabilization of the hydrated HKrCCH complexes have been investigated using the quantum chemical calculations on the HKrCCH-(H2O)n=1-6 clusters. Structure and energetics calculations show that water stabilizes HKrCCH through the π hydrogen bond in which the OH group of water interacts with the C[triple bond, length as m-dash]C group of HKrCCH. A maximum of four water molecules can directly interact with the C[triple bond, length as m-dash]C of HKrCCH and after that only inter-hydrogen bonding takes place between the water molecules indicating that the primary hydration shell contains four water molecules. Atom in molecule analysis depicts that π hydrogen bonded complexes of the hydrated HKrCCH are cyclic structures in which the OKr interaction cooperates in the formation of strong O-HC[triple bond, length as m-dash]C interaction. Structure, energetics and charge analysis clearly established that krypton plays an important role in the stabilization as well as the formation of the primary hydration shell of hydrated HKrCCH complexes.

  12. Effect of hydration on the organo-noble gas molecule HKrCCH: role of krypton in the stabilization of hydrated HKrCCH complexes.

    PubMed

    Biswas, Biswajit; Singh, Prashant Chandra

    2015-11-11

    The effect of hydration on the fluorine free organo-noble gas compound HKrCCH and the role of krypton in the stabilization of the hydrated HKrCCH complexes have been investigated using the quantum chemical calculations on the HKrCCH-(H2O)n=1-6 clusters. Structure and energetics calculations show that water stabilizes HKrCCH through the π hydrogen bond in which the OH group of water interacts with the C[triple bond, length as m-dash]C group of HKrCCH. A maximum of four water molecules can directly interact with the C[triple bond, length as m-dash]C of HKrCCH and after that only inter-hydrogen bonding takes place between the water molecules indicating that the primary hydration shell contains four water molecules. Atom in molecule analysis depicts that π hydrogen bonded complexes of the hydrated HKrCCH are cyclic structures in which the OKr interaction cooperates in the formation of strong O-HC[triple bond, length as m-dash]C interaction. Structure, energetics and charge analysis clearly established that krypton plays an important role in the stabilization as well as the formation of the primary hydration shell of hydrated HKrCCH complexes. PMID:26523809

  13. Renshaw cells are inactive during motor inhibition elicited by the pontine microinjection of carbachol.

    PubMed

    Morales, F R; Engelhardt, J K; Pereda, A E; Yamuy, J; Chase, M H

    1988-04-12

    The present study was undertaken to determine whether the postsynaptic inhibition of motoneurons that occurs following the pontine microinjection of carbachol in the decerebrate cat is due to the activity of Renshaw cells. Thirty-two out of 37 Renshaw cells (86%) were spontaneously active prior to the administration of carbachol, whereas only 2 out of 13 Renshaw cells (15%) discharged during carbachol-induced motor inhibition. In addition, discrete inhibitory synaptic potentials were observed in 33% of the Renshaw cells from which intracellular recordings were obtained after carbachol administration, indicating that these cells were actively inhibited. The finding that a population of Renshaw cells, which inhibit motoneurons, were themselves inhibited during a period of profound motoneuron inhibition was quite unexpected. These results support the conclusion that Renshaw cells are not the inhibitory interneurons that are responsible for the powerful inhibition of motoneurons that occurs following the pontine microinjection of carbachol. PMID:3380320

  14. Carbachol promotes gastrointestinal function during oral resuscitation of burn shock

    PubMed Central

    Hu, Sen; Che, Jin-Wei; Tian, Yi-Jun; Sheng, Zhi-Yong

    2011-01-01

    AIM: To investigate the effect of carbachol on gastrointestinal function in a dog model of oral resuscitation for burn shock. METHODS: Twenty Beagle dogs with intubation of the carotid artery, jugular vein and jejunum for 24 h were subjected to 35% total body surface area full-thickness burns, and were divided into three groups: no fluid resuscitation (NR, n = 10), in which animals did not receive fluid by any means in the first 24 h post-burn; oral fluid resuscitation (OR, n = 8), in which dogs were gavaged with glucose-electrolyte solution (GES) with volume and rate consistent with the Parkland formula; and oral fluid with carbachol group (OR/CAR, n = 8), in which dogs were gavaged with GES containing carbachol (20 μg/kg), with the same volume and rate as the OR group. Twenty-four hours after burns, all animals were given intravenous fluid replacement, and 72 h after injury, they received nutritional support. Hemodynamic and gastrointestinal parameters were measured serially with animals in conscious and cooperative state. RESULTS: The mean arterial pressure, cardiac output and plasma volume dropped markedly, and gastrointestinal tissue perfusion was reduced obviously after the burn injury in all the three groups. Hemodynamic parameters and gastrointestinal tissue perfusion in the OR and OR/CAR groups were promoted to pre-injury level at 48 and 72 h, respectively, while hemodynamic parameters in the NR group did not return to pre-injury level till 72 h, and gastrointestinal tissue perfusion remained lower than pre-injury level until 120 h post-burn. CO2 of the gastric mucosa and intestinal mucosa blood flow of OR/CAR groups were 56.4 ± 4.7 mmHg and157.7 ± 17.7 blood perfusion units (BPU) at 24 h post-burn, respectively, which were significantly superior to those in the OR group (65.8 ± 5.8 mmHg and 127.7 ± 11.9 BPU, respectively, all P < 0.05). Gastric emptying and intestinal absorption rates of GES were significantly reduced to the lowest level (52.8% and

  15. The ? electronic band system of nickel acetylide, NiCCH

    NASA Astrophysics Data System (ADS)

    Johnson, Eric L.; Morse, Michael D.

    2015-08-01

    Optical spectra of the supersonically cooled NiCCH radical have been recorded in the 530-650 nm region using the resonant two-photon ionisation method, and five of the observed bands have been rotationally resolved. The rotationally resolved studies demonstrate that the ground state of NiCCH is of ? symmetry, corresponding to a 3d9 configuration on the nickel atom, with the hole located in a 3dδ orbital. Most of the observed bands are assigned to the ? electronic transition, which shows a progression in the Ni-C stretching mode, ν3. In addition, single excitations of the modes ν2 (C≡C stretch), ν4 (C≡C-H bend), and ν5 (Ni-C≡C bend) are observed, allowing these vibrational intervals to be determined for the ? state. Hot bands also allow the determination of ν5 in the ground ? state. Quantum chemical computations have also been performed, confirming that the ground state is of 2Δ symmetry. The results are placed in context via comparison to other monovalent, monoligated Ni complexes, particularly NiCu, NiH, and NiCN.

  16. Modeling carbachol-induced hippocampal network synchronization using hidden Markov models

    NASA Astrophysics Data System (ADS)

    Dragomir, Andrei; Akay, Yasemin M.; Akay, Metin

    2010-10-01

    In this work we studied the neural state transitions undergone by the hippocampal neural network using a hidden Markov model (HMM) framework. We first employed a measure based on the Lempel-Ziv (LZ) estimator to characterize the changes in the hippocampal oscillation patterns in terms of their complexity. These oscillations correspond to different modes of hippocampal network synchronization induced by the cholinergic agonist carbachol in the CA1 region of mice hippocampus. HMMs are then used to model the dynamics of the LZ-derived complexity signals as first-order Markov chains. Consequently, the signals corresponding to our oscillation recordings can be segmented into a sequence of statistically discriminated hidden states. The segmentation is used for detecting transitions in neural synchronization modes in data recorded from wild-type and triple transgenic mice models (3xTG) of Alzheimer's disease (AD). Our data suggest that transition from low-frequency (delta range) continuous oscillation mode into high-frequency (theta range) oscillation, exhibiting repeated burst-type patterns, occurs always through a mode resembling a mixture of the two patterns, continuous with burst. The relatively random patterns of oscillation during this mode may reflect the fact that the neuronal network undergoes re-organization. Further insight into the time durations of these modes (retrieved via the HMM segmentation of the LZ-derived signals) reveals that the mixed mode lasts significantly longer (p < 10-4) in 3xTG AD mice. These findings, coupled with the documented cholinergic neurotransmission deficits in the 3xTG mice model, may be highly relevant for the case of AD.

  17. Endothelial-dependent relaxant actions of carbachol and substance P in arterial smooth muscle.

    PubMed

    Bolton, T B; Clapp, L H

    1986-04-01

    In helical strips cut from the small mesenteric artery of guinea-pig (GPSMA) (0.3-0.6 mm o.d.) relaxations induced by substance P were more susceptible to damage of the endothelium by rubbing than were relaxations evoked by carbachol. Relaxations induced by 2-nicotin-amidoethyl nitrate (SG75) were unaffected by this procedure. Relaxations evoked by the calcium ionophore A23187 persisted when those to substance P had been abolished by rubbing the endothelium in GPSMA, rabbit mesenteric and rabbit ear arteries. In guinea-pig pulmonary artery and aorta relaxations to A23187 were lost after this treatment. Carbachol and SG75 were more effective in inhibiting phasic than tonic tension induced by noradrenaline in GPSMA, but substance P was more effective against tonic tension. In the GPSMA, carbachol and substance P inhibited tension produced by noradrenaline to similar extents. However, carbachol was less, and substance P much less effective in inhibiting tension evoked by high-potassium solution than by noradrenaline. Susceptibility of relaxations to blockade by haemoglobin in GPSMA was: substance P greater than carbachol greater than ATP greater than SG75. The membrane potential of smooth muscle cells in the media of the GPSMA was recorded by microelectrode. Carbachol, but not substance P, hyperpolarized the cells both in the presence and absence of noradrenaline at concentrations which relaxed the muscle. These results suggest a heterogeneity in the mechanisms of endothelial-dependent relaxations induced by various vascular relaxants. PMID:2423170

  18. REM sleep-like episodes of motoneuronal depression and respiratory rate increase are triggered by pontine carbachol microinjections in in situ perfused rat brainstem preparation.

    PubMed

    Brandes, Ivo F; Stettner, Georg M; Mörschel, Michael; Kubin, Leszek; Dutschmann, Mathias

    2011-05-01

    Hypoglossal nerve activity (HNA) controls the position and movements of the tongue. In persons with compromised upper airway anatomy, sleep-related hypotonia of the tongue and other pharyngeal muscles causes increased upper airway resistance, or total upper airway obstructions, thus disrupting both sleep and breathing. Hypoglossal nerve activity reaches its nadir, and obstructive episodes are longest and most severe, during rapid eye movement stage of sleep (REMS). Microinjections of a cholinergic agonist, carbachol, into the pons have been used in vivo to investigate the mechanisms of respiratory control during REMS. Here, we recorded inspiratory-modulated phrenic nerve activity and HNA and microinjected carbachol (25-50 nl, 10 mm) into the pons in an in situ perfused working heart-brainstem rat preparation (WHBP), an ex vivo model previously validated for studies of the chemical and reflex control of breathing. Carbachol microinjections were made into 40 sites in 33 juvenile rat preparations and, at 24 sites, they triggered depression of HNA with increased respiratory rate and little change of phrenic nerve activity, a pattern akin to that during natural REMS in vivo. The REMS-like episodes started 151 ± 73 s (SD) following microinjections, lasted 20.3 ± 4.5 min, were elicited most effectively from the dorsal part of the rostral nucleus pontis oralis, and were prevented by perfusion of the preparation with atropine. The WHBP offers a novel model with which to investigate cellular and neurochemical mechanisms of REMS-related upper airway hypotonia in situ without anaesthesia and with full control over the cellular environment.

  19. Changes in electrophysiological properties of cat hypoglossal motoneurons during carbachol-induced motor inhibition.

    PubMed

    Fung, S J; Yamuy, J; Xi, M C; Engelhardt, J K; Morales, F R; Chase, M H

    2000-12-01

    The control of hypoglossal motoneurons during sleep is important from a basic science perspective as well as to understand the bases for pharyngeal occlusion which results in the obstructive sleep apnea syndrome. In the present work, we used intracellular recording techniques to determine changes in membrane properties in adult cats in which atonia was produced by the injection of carbachol into the pontine tegmentum (AS-carbachol). During AS-carbachol, 86% of the recorded hypoglossal motoneurons were found to be postsynaptically inhibited on the basis of analyses of their electrical properties; the electrical properties of the remaining 14% were similar to motoneurons recorded during control conditions. Those cells that exhibited changes in their electrical properties during AS-carbachol also displayed large-amplitude inhibitory synaptic potentials. Following sciatic nerve stimulation, hypoglossal motoneurons which responded with a depolarizing potential during control conditions exhibited a hyperpolarizing potential during AS-carbachol. Both spontaneous and evoked inhibitory potentials recorded during AS-carbachol were comparable to those that have been previously observed in trigeminal and spinal cord motoneurons under similar experimental conditions as well as during naturally occurring active sleep. Calculations based on modeling the changes that we found in input resistance and membrane time constant with a three-compartment neuron model suggest that shunts are present in all three compartments of the hypoglossal motoneuron model. Taken together, these data indicate that postsynaptic inhibitory drives are widely distributed on the soma-dendritic tree of hypoglossal motoneurons during AS-carbachol. These postsynaptic inhibitory actions are likely to be involved in the pathophysiology of obstructive sleep apnea. PMID:11102580

  20. Selectivity of muscarinic agonists including (+/-)-aceclidine and antimuscarinics on the human intraocular muscles.

    PubMed

    Ishikawa, H; DeSantis, L; Patil, P N

    1998-08-01

    The average EC50 value and the maximum response of carbachol on the human circular ciliary muscle obtained within 24 h of postmortem hypoxia was 517 nmol/l and 135 mg, respectively. These values for carbachol did not differ significantly from that of the longitudinal ciliary muscle. However, when tested at 1 mumol/l of carbachol, the peak response of the longitudinal muscle occurred at 59 sec vs 173 sec for that of the circular muscle of 70 year old donors. The relative potency of the muscarinic agonists on the circular muscle was oxotremorine-M, 1 > carbachol, 1/4 > pilocarpine, 1/19 > aceclidine, 1/132. The relative order of potency of agonists was similar for the longitudinal muscle. Only pilocarpine and aceclidine were partial agonists which produced 80-85% of the maximum response. When compared with the EC50 values of aceclidine on the iris sphincter and the longitudinal ciliary muscles, the agonist potency was only 1/28 for the latter tissue. Implications of these findings in relation to the use of these agonists in glaucoma are discussed. The pKB values of muscarinic antagonists on the circular ciliary muscle were: atropine, 8.8; cyclopentolate, 7.8; tropicamide, 7.4; P.F. HHSiD, 7.0; pirenzepine, 6.4; and methoctramine, 5.7. Nearly equal pKB values of each antagonist were obtained for the longitudinal ciliary muscle and iris sphincter. Based on the affinity constants of various competitive antagonists, the human iris as well as ciliary muscles may contain M3, M2 or M4 subtypes of muscarinic receptors.

  1. The depolarizing action of acetylcholine or carbachol in intestinal smooth muscle.

    PubMed

    Bolton, T B

    1972-02-01

    1. The membrane potential of the longitudinal muscle of the guinea-pig ileum was recorded intracellularly with glass micro-electrodes.2. Acetylcholine or carbachol depolarized the membrane. The depolarization produced by 1.4 x 10(-6)M carbachol was only 3.6 mV less than that produced by 5.5 x 10(-5)M.3. When the change in size of the electrotonic potential was used to estimate the increase in membrane conductance produced by different concentrations of carbachol, the increase in conductance was about tenfold at 1.4 x 10(-6)M and about 100-fold at 5.5 x 10(-5)M. There was a significant (P < 0.025) regression of the change in size of the electrotonic potential on the logarithm of the concentration of carbachol over this dose range. This and other observations suggest that it is not the availability of receptors which curtails the depolarization produced by concentrations of carbachol in excess of 1.4 x 10(-6)M.4. Reducing the external sodium concentration shifted the level of peak depolarization produced by carbachol negatively, and increasing the external sodium concentration shifted it positively.5. Reducing the external chloride from 134 to 13 mM had no significant effect on the level of peak depolarization produced by carbachol. Reducing the external chloride to 7 mM shifted the level of peak depolarization 3.1 mV in a positive direction.6. Increasing the external potassium concentration had little effect on the level of peak depolarization produced by carbachol, and decreasing the external potassium shifted the level of peak depolarization positively.7. It was possible to account for the observed relationship between membrane potential and membrane conductance if the assumption was made that carbachol opens additional ion channels in the membrane which have an equilibrium potential of about -9 mV. It is suggested therefore that the depolarizing action of carbachol on this smooth muscle is limited by its equilibrium potential, and that the equilibrium potential

  2. Effect of calcium chloride on gross behavioural changes produced by carbachol and eserine in cats.

    PubMed

    Beleslin, D B; Samardzic, R; Krstić, S K; Strbac, M

    1982-01-01

    The effect of calcium chloride injected into the cerebral ventricles of group-housed unanaesthetized cats upon vocalization (rage, hissing and snarling), fighting (attack with paws and claws, defense with paws and claws and biting), mydriasis, tremor and clonic-tonic convulsions produced by carbachol and eserine injected similarly was investigated. Calcium chloride depressed or almost completely abolished the vocalization and fighting due to carbachol and eserine. On the other hand, mydriasis, tremor and clonic-tonic convulsions evoked by carbachol and eserine were not significantly changed by calcium chloride. It is apparent that calcium chloride can "dissociate" vocalization and fighting from autonomic and motor phenomena such as mydriasis, tremor and clonic-tonic convulsions caused by carbachol and eserine. Calcium chloride inhibited the vocalization and fighting produced by carbachol and eserine most probably by a nonspecific stabilizing action on central muscarinic cholinoceptive sites. These results further support the view that calcium ions in excess have an atropine-like action also in the central nervous system. PMID:6892185

  3. Prostaglandins and muscarinic agonists induce cyclic AMP attenuation by two distinct mechanisms in the pregnant-rat myometrium. Interaction between cyclic AMP and Ca2+ signals.

    PubMed Central

    Goureau, O; Tanfin, Z; Harbon, S

    1990-01-01

    In pregnant-rat myometrium (day 21 of gestation), isoprenaline-induced cyclic AMP accumulation, resulting from receptor-mediated activation of adenylate cyclase, was negatively regulated by prostaglandins [PGE2, PGF2 alpha; EC50 (concn. giving 50% of maximal response) = 2 nM] and by the muscarinic agonist carbachol (EC50 = 2 microM). PG-induced inhibition was prevented by pertussis-toxin treatment, supporting the idea that it was mediated by the inhibitory G-protein Gi through the inhibitory pathway of the adenylate cyclase. Both isoprenaline-induced stimulation and PG-evoked inhibition of cyclic AMP were insensitive to Ca2+ depletion. By contrast, carbachol-evoked attenuation of cyclic AMP accumulation was dependent on Ca2+ and was insensitive to pertussis toxin. The inhibitory effect of carbachol was mimicked by ionomycin. Indirect evidence was thus provided for the enhancement of cyclic AMP degradation by a Ca2(+)-dependent phosphodiesterase activity in the muscarinic-mediated effect. The attenuation of cyclic AMP elicited by carbachol coincided with carbachol-stimulated inositol phosphate (InsP3, InsP2 and InsP) generation, which displayed an almost identical EC50 (3 microM) and was similarly unaffected by pertussis toxin. Both carbachol effects were reproduced by oxotremorine, whereas pilocarpine (a partial muscarinic agonist) failed to induce any decrease in cyclic AMP accumulation and concurrently was unable to stimulate the generation of inositol phosphates. These data support our proposal for a carbachol-mediated enhancement of a Ca2(+)-dependent phosphodiesterase activity, compatible with the rises in Ca2+ associated with muscarinic-induced increased generation of inositol phosphates. They further illustrate that a cross-talk between the two major transmembrane signalling systems contributed to an ultimate decrease in cyclic AMP in the pregnant-rat myometrium near term. PMID:1700899

  4. Amyloid beta-peptide disrupts carbachol-induced muscarinic cholinergic signal transduction in cortical neurons.

    PubMed

    Kelly, J F; Furukawa, K; Barger, S W; Rengen, M R; Mark, R J; Blanc, E M; Roth, G S; Mattson, M P

    1996-06-25

    Cholinergic pathways serve important functions in learning and memory processes, and deficits in cholinergic transmission occur in Alzheimer disease (AD). A subset of muscarinic cholinergic receptors are linked to G-proteins that activate phospholipase C, resulting in the liberation of inositol trisphosphate and Ca2+ release from intracellular stores. We now report that amyloid beta-peptide (Abeta), which forms plaques in the brain in AD, impairs muscarinic receptor activation of G proteins in cultured rat cortical neurons. Exposure of rodent fetal cortical neurons to Abeta25-35 and Abeta1-40 resulted in a concentration and time-dependent attenuation of carbachol-induced GTPase activity without affecting muscarinic receptor ligand binding parameters. Downstream events in the signal transduction cascade were similarly attenuated by Abeta. Carbachol-induced accumulation of inositol phosphates (IP, IP2, IP3, and IP4) was decreased and calcium imaging studies revealed that carbachol-induced release of calcium was severely impaired in neurons pretreated with Abeta. Muscarinic cholinergic signal transduction was disrupted with subtoxic levels of exposure to AP. The effects of Abeta on carbachol-induced GTPase activity and calcium release were attenuated by antioxidants, implicating free radicals in the mechanism whereby Abeta induced uncoupling of muscarinic receptors. These data demonstrate that Abeta disrupts muscarinic receptor coupling to G proteins that mediate induction of phosphoinositide accumulation and calcium release, findings that implicate Abeta in the impairment of cholinergic transmission that occurs in AD. PMID:8692890

  5. Stretch-induced myogenic responses of airways after histamine and carbachol.

    PubMed

    Thulesius, O; Mustafa, S

    1994-03-01

    The purpose of the study described here was to determine the possible role of a myogenic response of bronchial smooth muscle in deep inspiration (DI)-induced bronchoconstriction. Model experiments were performed on sheep tracheal strips. The effect of sudden stepwise elongation on isometric tension of tracheal muscle was studied in the absence and presence of the bronchoconstrictors carbachol (10(-8) M) and histamine (10(-4) M). In control strips tension increased rapidly with stretch and was followed by stress relaxation which corresponds to creep or bronchial dilatation. In histamine- and carbachol-treated strips a reactive contraction with a rhythmic pattern interrupted the process of stress relaxation. These responses appeared after only 20% elongation and were characteristic of a myogenic contraction which in the in vivo situation would correspond to a bronchoconstriction. These findings are interpreted as a functional transformation of multiple- to single-unit smooth muscle due to the influence of carbachol and histamine. This suggests that stretching (DI) of bronchial smooth muscle in the presence of carbachol and histamine induces a protracted myogenic contraction, which may explain bronchoconstriction after DI in severe asthma. PMID:8205744

  6. Regional haemodynamic effects of carbachol injected into the hypothalamic paraventricular nuclei of conscious, unrestrained rats.

    PubMed

    Bachelard, H; Gardiner, S M; Kemp, P A; Bennett, T

    1994-06-01

    Carbachol was injected into the hypothalamic paraventricular nuclei (PVN) of conscious, unrestrained Long Evans rats, chronically instrumented with intravascular catheters and pulsed Doppler probes to assess changes in regional haemodynamics. Bilateral microinjections of carbachol (1 ng-1 microgram) produced increases in blood pressure, bradycardias and vasoconstrictions in renal, superior mesenteric and hindquarters vascular beds. In the presence of phentolamine, the bradycardic and hindquarters vasoconstrictor responses to carbachol were unchanged while the pressor response was smaller due to a reduction in the renal and the superior mesenteric vasoconstriction. In the presence of propranolol, the bradycardic response was reduced, but the pressor and renal vasoconstrictor responses were potentiated, whereas the superior mesenteric and hindquarter vasoconstrictions were not changed significantly. In the presence of phentolamine and propranolol, the heart rate and pressor responses, as well as the renal vasoconstriction, were unchanged, whereas the superior mesenteric vasoconstriction was reduced and the hindquarters vasoconstriction was potentiated. Together these results are consistent with an involvement of the sympathoadrenal system in the pressor response to carbachol injected into the PVN of untreated animals. They indicate that alpha-adrenoceptor-mediated vasoconstriction in the superior mesenteric vascular bed is a particularly important component in that regard. In the presence of the vasopressin antagonist, d(CH2)5(Tyr(Et))DAVP, alone or in combination with phentolamine and propranolol, the pressor response to carbachol was substantially reduced, while the renal and superior mesenteric vasoconstrictor effects were completely abolished; the bradycardia was not significantly affected by this treatment. These results indicate an important involvement of vasopressin in the cardiovascular responses to carbachol injected into the PVN of untreated animals

  7. The effect of M & B 22948 on carbachol-induced inositol trisphosphate accumulation and contraction in iris sphincter smooth muscle.

    PubMed

    Akhtar, R A; Abdel-Latif, A A

    1991-04-25

    The effect of a cyclic GMP phosphodiesterase inhibitor, M & B 22948, on carbachol-induced phosphatidylinositol 4,5-bis-phosphate (PIP2) breakdown and phosphatidic acid labeling, 1,4,5-inositol trisphosphate (IP3) accumulation and muscle contraction was studied in bovine iris sphincter smooth muscle. Addition of carbachol (10 microM) to 32P-labeled tissue resulted in increased labeling of phosphatidic acid and hydrolysis of PIP2. In myo[3H]inositol labeled tissue, carbachol caused rapid accumulation of IP3 which reached its maximum at about 2 min. Under identical experimental conditions, carbachol initiated a rapid increase in muscle contraction (phasic component) which was followed by a slightly lower contractile response (tonic component) that lasted for several minutes. Pretreatment of the iris sphincter with M & B 22948 did not alter carbachol-stimulated PIP2 breakdown and phosphatidic acid labeling, IP3 accumulation, or phasic component of the contractile response. However, the tonic component of the contractile response was increasingly attenuated by increasing concentrations of the drug. In conclusion, the data presented demonstrate a close correlation between carbachol-induced IP3 accumulation and muscle contraction, and that M & B 22948 does not inhibit carbachol-induced responses in the iris sphincter.

  8. Ion-molecule calculation of the abundance ratio of CCD to CCH in dense interstellar clouds

    NASA Technical Reports Server (NTRS)

    Herbst, Eric; Adams, Nigel G.; Smith, David; Defrees, D. J.

    1987-01-01

    Laboratory measurements and calculations have been performed to determine the abundance ratio of the deuterated ethynyl radical (CCD) to the normal radical (CCH) which can be achieved in dense interstellar clouds via isotopic fractionation in the C2H2(+) (HD)=C2HD(+)(H2) system of reactions. According to this limited treatment, the CCD/CCH abundance ratio which can be attained is in the range 0.02-0.03 for the Orion molecular cloud and 0.0l-0.02 for TMC-1. These ranges of numbers are in reasonable agreement with the observed values in Orion and TMC-1. However, the analysis of the CCD/CCH abundance ratio is complicated via the presence of competing fractionation mechanisms, especially in the low-temperature source TMC-1.

  9. Ion-molecule calculation of the abundance ratio of CCD to CCH in dense interstellar clouds.

    PubMed

    Herbst, E; Adams, N G; Smith, D; DeFrees, D J

    1987-01-01

    Laboratory measurements and calculations have been performed to determine the abundance ratio of the deuterated ethynyl radical (CCD) to the normal radical (CCH) which can be achieved in dense interstellar clouds via isotopic fractionation in the C2H2+ (HD) = C2HD+ (H2) system of reactions. According to this limited treatment, the CCD/CCH abundance ratio which can be attained is in the range 0.02-0.03 for the Orion molecular cloud and 0.01-0.02 for TMC-1. These ranges of numbers are in reasonable agreement with the observed values in Orion and TMC-1. However, the analysis of the CCD/CCH abundance ratio is complicated via the presence of competing fractionation mechanisms, especially in the low-temperature source TMC-1.

  10. Sensitivity-Enhanced MQ-HCN-CCH-TOCSY and MQ-HCN-CCH-COSY Pulse Schemes for 13C/ 15N Labeled RNA Oligonucleotides

    NASA Astrophysics Data System (ADS)

    Hu, Weidong; Jiang, Licong; Gosser, Yuying Q.

    2000-07-01

    Sensitivity enhanced multiple-quantum 3D HCN-CCH-TOCSY and HCN-CCH-COSY experiments are presented for the ribose resonance assignment of 13C/15N-labeled RNA sample. The experiments make use of the chemical shift dispersion of N1/N9 of pyrimidine/purine to distinguish the ribose spin systems. They provide a complementary approach for the assignment of ribose resonance to the currently used HCCH-COSY and HCCH-TOCSY type experiments in which either 13C or 1H is utilized to separate the different ribose spin systems. The pulse schemes have been demonstrated on a 23-mer 13C/15N-labeled RNA aptamer complexed with neomycin and tested on a 32-mer RNA complexed with a 23-residue peptide.

  11. From synapse to gene product: Prolonged expression of c-fos induced by a single microinjection of carbachol in the pontomesencephalic tegmentum

    PubMed Central

    Quattrochi, James J.; Bazalakova, Mihaela; Hobson, J. Allan

    2006-01-01

    It is not known how the brain modifies its regulatory systems in response to the application of a drug, especially over the long term of weeks and months. We have developed a model system approach to this question by manipulating cholinergic cell groups of the laterodorsal and pedunculopontine tegmental (LDT/PPT) nuclei in the pontomesencephalic tegmentum (PMT), which are known to be actively involved in the timing and quantity of rapid eye movement (REM) sleep. In a freely moving feline model, a single microinjection of the cholinergic agonist carbachol conjugated to a latex nanosphere delivery system into the caudolateral PMT elicits a long-term enhancement of one distinguishing phasic event of REM sleep, ponto-geniculo-occipital (PGO) waves, lasting 5 days but without any significant change in REM sleep or other behavioral state. Here, we test the hypothesis that cholinergic activation within the caudolateral PMT alters the postsynaptic excitability of the PGO network, stimulating the prolonged expression of c-fos that underlies this long-term PGO enhancement (LTPE) effect. Using quantitative Fos immunohistochemistry, we found that the number of Fos-immunoreactive (Fos-IR) neurons surrounding the caudolateral PMT injection site decreased sharply by postcarbachol day 03, while the number of Fos-IR neurons in the more rostral LDT/PPT increased >30-fold and remained at a high level following the course of LTPE. These results demonstrate a sustained c-fos expression in response to pharmacological stimulation of the brain and suggest that carbachol's acute effects induce LTPE via cholinergic receptors, with subsequent transsynaptic activation of the LDT/PPT maintaining the LTPE effect. PMID:15893601

  12. From synapse to gene product: prolonged expression of c-fos induced by a single microinjection of carbachol in the pontomesencephalic tegmentum.

    PubMed

    Quattrochi, James J; Bazalakova, Mihaela; Hobson, J Allan

    2005-05-20

    It is not known how the brain modifies its regulatory systems in response to the application of a drug, especially over the long term of weeks and months. We have developed a model system approach to this question by manipulating cholinergic cell groups of the laterodorsal and pedunculopontine tegmental (LDT/PPT) nuclei in the pontomesencephalic tegmentum (PMT), which are known to be actively involved in the timing and quantity of rapid eye movement (REM) sleep. In a freely moving feline model, a single microinjection of the cholinergic agonist carbachol conjugated to a latex nanosphere delivery system into the caudolateral PMT elicits a long-term enhancement of one distinguishing phasic event of REM sleep, ponto-geniculo-occipital (PGO) waves, lasting 5 days but without any significant change in REM sleep or other behavioral state. Here, we test the hypothesis that cholinergic activation within the caudolateral PMT alters the postsynaptic excitability of the PGO network, stimulating the prolonged expression of c-fos that underlies this long-term PGO enhancement (LTPE) effect. Using quantitative Fos immunohistochemistry, we found that the number of Fos-immunoreactive (Fos-IR) neurons surrounding the caudolateral PMT injection site decreased sharply by postcarbachol day 03, while the number of Fos-IR neurons in the more rostral LDT/PPT increased >30-fold and remained at a high level following the course of LTPE. These results demonstrate a sustained c-fos expression in response to pharmacological stimulation of the brain and suggest that carbachol's acute effects induce LTPE via cholinergic receptors, with subsequent transsynaptic activation of the LDT/PPT maintaining the LTPE effect.

  13. [The influence of L-glutamate and carbachol on burst firing of dopaminergic neurons in ventral tegmental area].

    PubMed

    Wang, Shan-shan; Wei, Chun-ling; Liu, Zhi-qiang; Ren, Wei

    2011-02-25

    Burst firing of dopaminergic neurons in ventral tegmental area (VTA) induces a large transient increase in synaptic dopamine (DA) release and thus is considered the reward-related signal. But the mechanisms of burst generation of dopaminergic neuron still remain unclear. This experiment investigated the burst firing of VTA dopaminergic neurons in rat midbrain slices perfused with carbachol and L-glutamate individually or simultaneously to understand the neurotransmitter mechanism underlying burst generation. The results showed that bath application of carbachol (10 μmol/L) and pulse application of L-glutamate (3 mmol/L) both induced burst firing in dopaminergic neuron. Co-application of carbachol and L-glutamate induced burst firing in VTA dopaminergic cells which couldn't be induced to burst by the two chemicals separately. The result indicates that carbachol and L-glutamate co-regulate burst firing of dopaminergic neuron.

  14. Effect of mineral salts, carbachol, and pilocarpine on nutrient digestibility and ruminal characteristics in cattle.

    PubMed

    Wiedmeier, R D; Arambel, M J; Lamb, R C; Marcinkowski, D P

    1987-03-01

    Fifty percent concentrate diets containing 2% sodium bicarbonate, sodium chloride, or no additional mineral salts were fed at a rate of 86 g dry matter/kg body weight X 75/d to three barren Holstein cows fitted with ruminal fistulas in a 3 X 3 Latin square design. Dietary adaptation was 14 d followed by 4 d collection. Ruminal pH, liquid volume, liquid dilution rate, and particulate rate of passage were increased with dietary mineral salts. Six Holstein cows fitted with ruminal fistulas were administered .01 mg carbachol/kg body weight/d, .10 mg pilocarpine/kg body weight/d, or saline placebo via subcutaneous, osmotically controlled pumps in a replicated 3 X 3 Latin square design. Treatments were administered for a 14-d adaptation period followed by an 8-d collection period. Both carbachol and pilocarpine increased liquid dilution rate, particulate rate of passage, and percent cellulolytic bacteria, whereas liquid volume was reduced.

  15. Relationships of nucleus reticularis pontis oralis neuronal discharge with sensory and carbachol evoked hippocampal theta rhythm.

    PubMed

    Nuñez, A; de Andrés, I; García-Austt, E

    1991-01-01

    The activity of 72 neurons recorded in the reticularis pontis oralis nucleus (RPO) was examined in anesthetized and curarized rats during hippocampal theta (theta) rhythm elicited by either sensory stimulation or carbachol microinjections. During hippocampal theta rhythm evoked by sensory stimulation, 63.9% of RPO neurons increased their discharge rate while the firing rate decreased in 20.8%. In all cases, the RPO neurons maintained a non-rhythmic discharge pattern. In 44% of the neurons the discharges tended to occur on the positive wave of the theta rhythm. Similar firing patterns were seen in 18 RPO neurons recorded during theta rhythm elicited by both, sensory stimulation and a carbachol microinjection; this effect was blocked by atropine. These results indicate that the RPO region contributes to the generation of hippocampal theta rhythm with a tonic and nonrhythmic outflow through a cholinergic system which may be muscarinic.

  16. Effects of nitric acid on carbachol reactivity of the airways in normal and allergic sheep

    SciTech Connect

    Abraham, W.M.; Kim, C.S.; King, M.M.; Oliver, W. Jr.; Yerger, L.

    1982-01-01

    The airway effects of a 4-hr exposure (via a Plexiglas hood) to 1.6 ppm nitric acid vapor were evaluated in seven normal and seven allergic sheep, i.e., animals that have a history of reacting with bronchospasm to inhalation challenge with Ascaris suum antigen. The nitric acid vapor was generated by ultrasonic nebulization of a 2% nitric acid solution. Airway effects were assessed by measuring the change in specific pulmonary flow resistance before and after a standard inhalation challenge with 2.5% carbachol aerosol. Nitric acid exposure did not produce bronchoconstriction in either group. Pre-exposure increases in specific pulmonary flow resistance after carbachol inhalation were 68% (SD+/- 13%) and 82% (SD+/- 35%) for the normal and allergic sheep, respectively. Within 24 hr, the largest post-exposure increases in specific pulmonary flow resistance for the normal and allergic sheep were 108% (SD+/- 51%(P<.06)) and 175% (SD+/- 87% (p<.02)), respectively. We conclude that a short-term exposure to nitric acid vapor at levels below the industrial threshold limit (2 ppm), produces airway hyperreactivity to aerosolized carbachol in allergic sheep.

  17. Analysis of agonist dissociation constants as assessed by functional antagonism in guinea pig left atria

    SciTech Connect

    Molenaar, P.; Malta, E.

    1986-04-01

    In electrically driven guinea pig left atria, positive inotropic responses to (-)-isoprenaline and the selective beta 1-adrenoceptor agonist RO363 were obtained in the absence and in the presence of the functional antagonists adenosine, carbachol, gallopamil, nifedipine, and Ro 03-7894. Each of the functional antagonists reduced the maximum response to both agonists and produced nonparallel rightward shifts in the cumulative concentration effect curves. For both agonists, dissociation constants (KA) were calculated using the equation described by Furchgott (1966) for irreversible antagonism. For RO363, which is a partial agonist with high agonist activity, the equations outlined for functional interaction by Mackay (1981) were also employed to calculate KA values. The KA values obtained by each method were compared with the dissociation constants (KD) for the two agonists determined from their ability to displace the radioligand (-)-(/sup 125/I)iodocyanopindolol from beta 1-adrenoceptors in guinea pig left atrial membrane preparations. The estimates of KA varied substantially from KD values. The KD values were taken as more accurate estimates of the true values for the dissociation constants because a high degree of correlation exists between pKD and pD2 values for a number of other beta-adrenoceptor agonists that behave as partial agonists and between pKD and pKB values for a number of beta-adrenoceptor antagonists. Thus, it appears that there are serious limitations in the current theory for using functional antagonism as a means of obtaining agonist dissociation constants.

  18. Cch1p mediates Ca2+ influx to protect Saccharomyces cerevisiae against eugenol toxicity.

    PubMed

    Roberts, Stephen K; McAinsh, Martin; Widdicks, Lisa

    2012-01-01

    Eugenol has antifungal activity and is recognised as having therapeutic potential. However, little is known of the cellular basis of its antifungal activity and a better understanding of eugenol tolerance should lead to better exploitation of eugenol in antifungal therapies. The model yeast, Saccharomyces cerevisiae, expressing apoaequorin was used to show that eugenol induces cytosolic Ca(2+) elevations. We investigated the eugenol Ca(2+) signature in further detail and show that exponentially growing cells exhibit Ca(2+) elevation resulting exclusively from the influx of Ca(2+) across the plasma membrane whereas in stationary growth phase cells Ca(2+) influx from intracellular and extracellular sources contribute to the eugenol-induced Ca(2+) elevation. Ca(2+) channel deletion yeast mutants were used to identify the pathways mediating Ca(2+) influx; intracellular Ca(2+) release was mediated by the vacuolar Ca(2+) channel, Yvc1p, whereas the Ca(2+) influx across the plasma membrane could be resolved into Cch1p-dependent and Cch1p-independent pathways. We show that the growth of yeast devoid the plasma membrane Ca(2+) channel, Cch1p, was hypersensitive to eugenol and that this correlated with reduced Ca(2+) elevations. Taken together, these results indicate that a cch1p-mediated Ca(2+) influx is part of an intracellular signal which protects against eugenol toxicity. This study provides fresh insight into the mechanisms employed by fungi to tolerate eugenol toxicity which should lead to better exploitation of eugenol in antifungal therapies.

  19. Autoantibodies enhance agonist action and binding to cardiac muscarinic receptors in chronic Chagas' disease.

    PubMed

    Hernandez, Ciria C; Nascimento, Jose H; Chaves, Elen A; Costa, Patricia C; Masuda, Masako O; Kurtenbach, Eleonora; Campos DE Carvalho, Antonio C; Gimenez, Luis E

    2008-01-01

    Chronic Chagasic patient immunoglobulins (CChP-IgGs) recognize an acidic amino acid cluster at the second extracellular loop (el2) of cardiac M(2)-muscarinic acetylcholine receptors (M(2)AChRs). These residues correspond to a common binding site for various allosteric agents. We characterized the nature of the M(2)AChR/CChP-IgG interaction in functional and radioligand binding experiments applying the same mainstream strategies previously used for the characterization of other allosteric agents. Dose-response curves of acetylcholine effect on heart rate were constructed with data from isolated heart experiments in the presence of CChP or normal blood donor (NBD) sera. In these experiments, CChP sera but not NBD sera increased the efficacy of agonist action by augmenting the onset of bradyarrhythmias and inducing a Hill slope of 2.5. This effect was blocked by gallamine, an M(2)AChR allosteric antagonist. Correspondingly, CChP-IgGs increased acetylcholine affinity twofold and showed negative cooperativity for [(3)H]-N-methyl scopolamine ([(3)H]-NMS) in allosterism binding assays. A peptide corresponding to the M(2)AChR-el2 blocked this effect. Furthermore, dissociation assays showed that the effect of gallamine on the [(3)H]-NMS off-rate was reverted by CChP-IgGs. Finally, concentration-effect curves for the allosteric delay of W84 on [(3)H]-NMS dissociation right shifted from an IC(50) of 33 nmol/L to 78 nmol/L, 992 nmol/L, and 1670 nmol/L in the presence of 6.7 x 10(- 8), 1.33 x 10(- 7), and 2.0 x 10(- 7) mol/L of anti-el2 affinity-purified CChP-IgGs. Taken together, these findings confirmed a competitive interplay of these ligands at the common allosteric site and revealed the novel allosteric nature of the interaction of CChP-IgGs at the M(2)AChRs as a positive cooperativity effect on acetylcholine action. PMID:18702010

  20. Autoantibodies Enhance Agonist Action and Binding to Cardiac Muscarinic Receptors in Chronic Chagas’ Disease

    PubMed Central

    Hernández, Ciria C.; Nascimento, José H.; Chaves, Elen A.; Costa, Patrícia C.; Masuda, Masako O.; Kurtenbach, Eleonora; Campos de Carvalho, Antônio C.; Giménez, Luis E.

    2009-01-01

    Chronic Chagasic patient immunoglobulins (CChP-IgGs) recognize an acidic amino acid cluster at the second extracellular loop (el2) of cardiac M2-muscarinic acetylcholine receptors (M2AChRs). These residues correspond to a common binding site for various allosteric agents. We characterized the nature of the M2AChR/CChP-IgG interaction in functional and radioligand binding experiments applying the same mainstream strategies previously used for the characterization of other allosteric agents. Dose-response curves of acetylcholine effect on heart rate were constructed with data from isolated heart experiments in the presence of CChP or normal blood donor (NBD) sera. In these experiments, CChP sera but not NBD sera increased the efficacy of agonist action by augmenting the onset of bradyarrhythmias and inducing a Hill slope of 2.5. This effect was blocked by gallamine, an M2AChR allosteric antagonist. Correspondingly, CChP-IgGs increased acetylcholine affinity twofold and showed negative cooperativity for [3H]-N-methyl scopolamine ([3H]-NMS) in allosterism binding assays. A peptide corresponding to the M2AChR-el2 blocked this effect. Furthermore, dissociation assays showed that the effect of gallamine on the [3H]-NMS off-rate was reverted by CChP-IgGs. Finally, concentration-effect curves for the allosteric delay of W84 on [3H]-NMS dissociation right shifted from an IC50 of 33 nmol/L to 78 nmol/L, 992 nmol/L, and 1670 nmol/L in the presence of 6.7 × 10−8, 1.33 × 10−7, and 2.0 × 10−7 mol/L of anti-el2 affinity-purified CChP-IgGs. Taken together, these findings confirmed a competitive interplay of these ligands at the common allosteric site and revealed the novel allosteric nature of the interaction of CChP-IgGs at the M2AChRs as a positive cooperativity effect on acetylcholine action. PMID:18702010

  1. C-fos expression in the pons and medulla of the cat during carbachol-induced active sleep.

    PubMed

    Yamuy, J; Mancillas, J R; Morales, F R; Chase, M H

    1993-06-01

    Microinjection of carbachol into the rostral pontine tegmentum of the cat induces a state that is comparable to naturally occurring active (REM, rapid eye movement) sleep. We sought to determine, during this pharmacologically induced behavioral state, which we refer to as active sleep-carbachol, the distribution of activated neuron within the pons and medulla using c-fos immunocytochemistry as a functional marker. Compared with control cats, which were injected with saline, active sleep-carbachol cats exhibited higher numbers of c-fos-expressing neurons in (1) the medial and portions of the lateral reticular formation of the pons and medulla, (2) nuclei in the dorsolateral rostral pons, (3) various raphe nuclei, including the dorsal, central superior, magnus, pallidus, and obscurus, (4) the medial and lateral vestibular, prepositus hypoglossi, and intercalatus nuclei, and (5) the abducens nuclei. On the other hand, the mean number of c-fos-expressing neurons found in the masseter, facial, and hypoglossal nuclei was lower in carbachol-injected than in control cats. The data indicate that c-fos expression can be employed as a marker of state-dependent neuronal activity. The specific sites in which there were greater numbers of c-fos-expressing neurons during active sleep-carbachol are discussed in relation to the state of active sleep, as well as the functional role that these sites play in generating the various physiological patterns of activity that occur during this state. PMID:8501533

  2. Gudden's dorsal tegmental nucleus is activated in carbachol-induced active (REM) sleep and active wakefulness.

    PubMed

    Torterolo, Pablo; Sampogna, Sharon; Morales, Francisco R; Chase, Michael H

    2002-07-19

    Previous studies have shown that GABAergic processes in the ponto-mesencephalic region of the brainstem are involved in the generation of wakefulness and active sleep (AS). The dorsal and ventral tegmental nuclei of Gudden (DTN and VTN, respectively) are known to contain a large population of GABAergic neurons. In the present study, utilizing Fos immunoreactivity as a marker of neuronal activity, it was determined that GABAergic DTN pars dorsalis neurons are active during active wakefulness and AS induced by carbachol, but not during quiet wakefulness or quiet sleep. In contrast, no differences in the number of Fos immunoreactive neurons were observed in the DTN pars ventralis and VTN across behavioral states.

  3. Thermodynamic modeling of the C(CH2OH)4-(NH2)(CH3)C(CH2OH)2 binary system

    SciTech Connect

    Chellappa, Raja; Russell, Renee; Chandra, Dhanesh

    2004-10-12

    A new calculated phase diagram of pentaerythritol [PE:P C(CH2OH)4]-2-amino-2-methyl-1,3-propanediol [AMPL: (NH2)(CH3)C(CH2OH)2 ] 'plastic crystals' is presented. The low temperature PE-rich * phase has a tetragonal structure whereas the AMPL-rich * phase has a monoclinic structure. Upon heating, these low temperature * or * phases transform to a high temperature * or *' plastic crystal phases. The PE-rich * phase has an FCC structure and the AMPL-rich *' phase has a BCC structure. The system exhibits complex behavior with one low temperature peritectoid, a high temperature eutectoid, and a peritectic. The * and * phases are assumed to be regular solutions and the plastic crystal phases (* and *') are described using sub-regular solution models. The optimization for excess Gibbs energy parameters was perfomred using Thermo-Calc (TCC) software. The magnitudes of the interaction parameters are relatively large compared to those for similar plastic crystal binary systems.

  4. Generation and orientation of organoxenon molecule H-Xe-CCH in the gas phase

    SciTech Connect

    Poterya, Viktoriya; Votava, Ondrej; Farnik, Michal; Oncak, Milan; Slavicek, Petr; Buck, Udo; Friedrich, Bretislav

    2008-03-14

    We report on the first observation of the organoxenon HXeCCH molecule in the gas phase. This molecule has been prepared in a molecular beam experiment by 193 nm photolysis of an acetylene molecule on Xe{sub n} clusters (n{approx_equal}390). Subsequently the molecule has been oriented via the pseudo-first-order Stark effect in a strong electric field of the polarized laser light combined with the weak electrostatic field in the extraction region of a time-of-flight spectrometer. The experimental evidence for the oriented molecule has been provided by measurements of its photodissociation. For comparison, photolysis of C{sub 2}H{sub 2} on Ar{sub n} clusters (n{approx_equal}280) has been measured. Here the analogous rare gas molecule HArCCH could not be generated. The interpretation of our experimental findings has been supported by ab initio calculations. In addition, the experiment together with the calculations reveals information on the photochemistry of the HXeCCH molecule. The 193 nm radiation excites the molecule predominantly into the 2 {sup 1}{sigma}{sup +} state, which cannot dissociate the Xe-H bond directly, but the system evolves along the Xe-C coordinate to a conical intersection of a slightly nonlinear configuration with the dissociative 1 {sup 1}{pi} state, which then dissociates the Xe-H bond.

  5. Mechanism of carbachol-evoked contractions of guinea-pig ileal smooth muscle close to freezing point.

    PubMed Central

    Blackwood, A. M.; Bolton, T. B.

    1993-01-01

    1. The effect of lowering the temperature to near freezing-point upon the contractions and [3H]-inositol phosphate responses to carbachol were investigated in longitudinal smooth muscle from the guinea-pig ileum. 2. The peak amplitude of the contraction to a single application of 100 microM carbachol was the same at 37 degrees C and temperatures near freezing-point. However, the sensitivity to carbachol was reduced upon lowering the temperature and the time to peak contraction was increased from 5-10 s to 2-10 min. Even when the temperature was maintained near freezing-point, washing off carbachol produced a relaxation and eventual return of tension to basal levels. 3. Incubating the tissue in 140 mM K+, calcium-free solution or in calcium channel antagonists significantly reduced the carbachol-induced contraction to 10-30% of the control at 37 degrees C and also at 3 degrees C. Thus the majority of the activator calcium required for contraction entered the tissue via voltage-dependent calcium channels (VDCs) at both 37 degrees C and 3 degrees C. 4. The contractions produced by high potassium solutions were less at temperatures close to freezing-point than those at 37 degrees C suggesting that voltage-dependent calcium entry was inhibited as the temperature was lowered. 5. A small part of the contractile response to 100 microM carbachol was resistant to the removal of extracellular calcium at both 37 degrees C and 3 degrees C and this component was increased under depolarizing conditions.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8401915

  6. In vitro effect of nicorandil on the carbachol-induced contraction of the lower esophageal sphincter of the rat.

    PubMed

    Shimbo, Tomonori; Adachi, Takeshi; Fujisawa, Susumu; Hongoh, Mai; Ohba, Takayoshi; Ono, Kyoichi

    2016-08-01

    The lower esophageal sphincter (LES) is a specialized region of the esophageal smooth muscle that allows the passage of a swallowed bolus into the stomach. Nitric oxide (NO) plays a major role in LES relaxation. Nicorandil possesses dual properties of a NO donor and an ATP-sensitive potassium channel (KATP channel) agonist, and is expected to reduce LES tone. This study investigated the mechanisms underlying the effects of nicorandil on the LES. Rat LES tissues were placed in an organ bath, and activities were recorded using an isometric force transducer. Carbachol-induced LES contraction was significantly inhibited by KATP channel agonists in a concentration-dependent manner; pinacidil > nicorandil ≈ diazoxide. Nicorandil-induced relaxation of the LES was prevented by pretreatment with glibenclamide, whereas N(G)-nitro-l-arginine methyl ester (l-NAME), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and iberiotoxin were ineffective at preventing nicorandil-induced LES relaxation. Furthermore, nicorandil did not affect high K(+)-induced LES contraction. Reverse-transcription polymerase chain reaction analysis and immunohistochemistry revealed expression of KCNJ8 (Kir6.1), KCNJ11 (Kir6.2), ABCC8 (SUR1) and ABCC9 (SUR2) subunits of the KATP channel in the rat lower esophagus. These findings indicate that nicorandil causes LES relaxation chiefly by activating the KATP channel, and that it may provide an additional pharmacological tool for the treatment of spastic esophageal motility disorders. PMID:27562702

  7. Fos expression in pontomedullary catecholaminergic cells following rapid eye movement sleep-like episodes elicited by pontine carbachol in urethane-anesthetized rats.

    PubMed

    Rukhadze, I; Fenik, V B; Branconi, J L; Kubin, L

    2008-03-01

    Pontine noradrenergic neurons of the locus coeruleus (LC) and sub-coeruleus (SubC) region cease firing during rapid eye movement sleep (REMS). This plays a permissive role in the generation of REMS and may contribute to state-dependent modulation of transmission in the CNS. Whether all pontomedullary catecholaminergic neurons, including those in the A1/C1, A2/C2 and A7 groups, have REMS-related suppression of activity has not been tested. We used Fos protein expression as an indirect marker of the level of neuronal activity and linear regression analysis to determine whether pontomedullary cells identified by tyrosine hydroxylase (TH) immunohistochemistry have reduced Fos expression following REMS-like state induced by pontine microinjections of a cholinergic agonist, carbachol in urethane-anesthetized rats. The percentage of Fos-positive TH cells was negatively correlated with the cumulative duration of REMS-like episodes induced during 140 min prior to brain harvesting in the A7 and rostral A5 groups bilaterally (P < 0.01 for both), and in SubC neurons on the side opposite to carbachol injection (P < 0.05). Dorsal medullary A2/C2 neurons did not exhibit such correlation, but their Fos expression (and that in A7, rostral A5 and SubC neurons) was positively correlated with the duration of the interval between the last REMS-like episode and the time of perfusion (P < 0.05). In contrast, neither of these correlations was significant for A1 /C1 or caudal A5 neurons. These findings suggest that, similar to the prototypic LC neurons, neurons of the A7, rostral A5 and A2/C2 groups have reduced or abolished activity during REMS, whereas A1 /IC1 and caudal A5 neurons do not have this feature. The reduced activity of A2/C2, A5 and A7 neurons during REMS, and the associated decrements in norepinephrine release, may cause state-dependent modulation of.transmission in brain somato- and viscerosensory, somatomotor, and cardiorespiratory pathways.

  8. GABAergic neurons of the cat dorsal raphe nucleus express c-fos during carbachol-induced active sleep.

    PubMed

    Torterolo, P; Yamuy, J; Sampogna, S; Morales, F R; Chase, M H

    2000-11-24

    Serotonergic neurons of the dorsal raphe nucleus (DRN) cease firing during active sleep (AS, also called rapid-eye-movement sleep). This cessation of electrical activity is believed to play a 'permissive' role in the generation of AS. In the present study we explored the possibility that GABAergic cells in the DRN are involved in the suppression of serotonergic activity during AS. Accordingly, we examined whether immunocytochemically identified GABAergic neurons in the DRN were activated, as indicated by their expression of c-fos, during carbachol-induced AS (AS-carbachol). Three chronically-prepared cats were euthanized after prolonged episodes of AS that was induced by microinjections of carbachol into the nucleus pontis oralis. Another four cats (controls) were maintained 2 h in quiet wakefulness before being euthanized. Thereafter, immunocytochemical studies were performed on brainstem sections utilizing antibodies against Fos, GABA and serotonin. When compared with identically prepared tissue from awake cats, the number of Fos+ neurons was larger in the DRN during AS-carbachol (35.9+/-5.6 vs. 13.9+/-4.4, P<0.05). Furthermore, a larger number of GABA+ Fos+ neurons were observed during AS-carbachol than during wakefulness (24.8+/-3.3 vs. 4.0+/-1.0, P<0.001). These GABA+ Fos+ neurons were distributed asymmetrically with a larger number located ipsilaterally to the site of injection. There was no significant difference between control and experimental animals in the number of non-GABAergic neurons that expressed c-fos in the DRN. We therefore suggest that activated GABAergic neurons of the DRN are responsible for the inhibition of serotonergic neurons that occurs during natural AS. PMID:11082488

  9. The effect of sodium removal on the contractile response of the guinea-pig taenia coli to carbachol.

    PubMed Central

    Brading, A F; Burnett, M; Sneddon, P

    1980-01-01

    1. The effects of Na-free solutions (using Li, Tris, sucrose or Mg as Na substitutes) on the contractile responses, membrane depolarization and 42K efflux produced by carbachol in the smooth muscle of the guinea-pig taenia coli have been investigated. The effect of these Na-free solutions on intracellular ion content of the muscle has also been studied. 2. Na removal induced a pattern of changes in the tone of the muscle characteristic of the substitute used, probably reflecting changes in transmembrane Ca fluxes involving Na. 3. Contractile responses to 10 sec application of 5 x 10(-5) M-carbachol were greatly reduced in Na-free solutions with all the Na substitutes used. This did not correlate with reduction in membrane depolarization or 42K efflux produced by the drug in the various Na-free medial used. 4. Intracellular Na seems important for maintaining the contractile response, since in Na-free solutions cellular Na levels and contractile responses were better maintained at 13 degrees than 34 degrees C and in tissues stimulated with carbachol every 10 min the final magnitude of the response was related to cellular Na content. If, however, the tissues was left unstimulated in Na-free Mg or sucrose solution a large response could still be obtained when cellular Na content was very low. A model is described which could account for these results in terms of an intracellular Ca store released by carbachol and requiring intracellular Na. 5. In tissues continuously exposed to 10(-4) M-carbachol Na removal, even for only 10 sec, produced rapid relaxation, probably secondary to changes in electrical properties of the membrane caused by removal of external Na. PMID:7463367

  10. Population synaptic potentials evoked in lumbar motoneurons following stimulation of the nucleus reticularis gigantocellularis during carbachol-induced atonia.

    PubMed

    Yamuy, J; Jiménez, I; Morales, F; Rudomin, P; Chase, M

    1994-03-14

    The effect of electrical stimulation of the medullary nucleus reticularis gigantocellularis (NRGc) on lumbar spinal cord motoneurons was studied in the decerebrate cat using sucrose-gap recordings from ventral roots. The NRGc was stimulated ipsi- and contralaterally before and during atonia elicited by the microinjection of carbachol into the pontine reticular formation. Prior to carbachol administration, the NRGc-induced response recorded from the sucrose-gap consisted of two consecutive excitatory population synaptic potentials followed by a long-lasting, small amplitude inhibitory population synaptic potential. Following carbachol injection, the same NRGc stimulus evoked a distinct, large amplitude inhibitory population synaptic potential, whereas the excitatory population synaptic potentials decreased in amplitude. In addition, after carbachol administration, the amplitude of the monosynaptic excitatory population synaptic potential, which was evoked by stimulation of group Ia afferents in hindlimb nerves, was reduced by 18 to 43%. When evoked at the peak of the NRGc-induced inhibitory response, this potential was further decreased in amplitude. Systemic strychnine administration (0.07-0.1 mg/kg, i.v.) blocked the NRGc-induced inhibitory population synaptic potential and promoted an increase in the amplitude of the excitatory population synaptic potentials induced by stimulation of the NRGc and group Ia afferents. These data indicate that during the state of carbachol-induced atonia, the NRGc effects on ipsi- and contralateral spinal cord motoneurons are predominantly inhibitory and that glycine is likely to be involved in this inhibitory process. These results support the hypothesis that the nucleus reticularis gigantocellularis is part of the system responsible for state-dependent somatomotor inhibition that occurs during active sleep. PMID:8205484

  11. Carbachol induces a rapid and sustained hydrolysis of polyphosphoinositide in bovine tracheal smooth muscle measurements of the mass of polyphosphoinositides, 1,2-diacylglycerol, and phosphatidic acid

    SciTech Connect

    Takuwa, Y.; Takuwa, N.; Rasmussen, H.

    1986-11-05

    The effects of carbachol on polyphosphoinositides and 1,2-diacylglycerol metabolism were investigated in bovine tracheal smooth muscle by measuring both lipid mass and the turnover of (/sup 3/H)inositol-labeled phosphoinositides. Carbachol induces a rapid reduction in the mass of phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 4-monophosphate and a rapid increase in the mass of 1,2-diacylglycerol and phosphatidic acid. These changes in lipid mass are sustained for at least 60 min. The level of phosphatidylinositol shows a delayed and progressive decrease during a 60-min period of carbachol stimulation. The addition of atropine reverses these responses completely. Carbachol stimulates a rapid loss in (/sup 3/H)inositol radioactivity from phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 4-monophosphate associated with production of (/sup 3/H)inositol trisphosphate. The carbachol-induced change in the mass of phosphoinositides and phosphatidic acid is not affected by removal of extracellular Ca/sup 2 +/ and does not appear to be secondary to an increase in intracellular Ca/sup 2 +/. These results indicate that carbachol causes phospholipase C-mediated polyphosphoinositide breakdown, resulting in the production of inositol trisphosphate and a sustained increase in the actual content of 1,2-diacylglycerol. These results strongly suggest that carbachol-induced contraction is mediated by the hydrolysis of polyphosphoinositides with the resulting generation of two messengers: inositol 1,4,5-trisphosphate and 1,2-diacylglycerol.

  12. Carbachol induces a rapid and sustained hydrolysis of polyphosphoinositide in bovine tracheal smooth muscle measurements of the mass of polyphosphoinositides, 1,2-diacylglycerol, and phosphatidic acid.

    PubMed

    Takuwa, Y; Takuwa, N; Rasmussen, H

    1986-11-01

    The effects of carbachol on polyphosphoinositides and 1,2-diacylglycerol metabolism were investigated in bovine tracheal smooth muscle by measuring both lipid mass and the turnover of [3H]inositol-labeled phosphoinositides. Carbachol induces a rapid reduction in the mass of phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 4-monophosphate and a rapid increase in the mass of 1,2-diacylglycerol and phosphatidic acid. These changes in lipid mass are sustained for at least 60 min. The level of phosphatidylinositol shows a delayed and progressive decrease during a 60-min period of carbachol stimulation. The addition of atropine reverses these responses completely. Carbachol stimulates a rapid loss in [3H]inositol radioactivity from phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 4-monophosphate associated with production of [3H]inositol trisphosphate. The carbachol-induced change in the mass of phosphoinositides and phosphatidic acid is not affected by removal of extracellular Ca2+ and does not appear to be secondary to an increase in intracellular Ca2+. These results indicate that carbachol causes phospholipase C-mediated polyphosphoinositide breakdown, resulting in the production of inositol trisphosphate and a sustained increase in the actual content of 1,2-diacylglycerol. These results strongly suggest that carbachol-induced contraction is mediated by the hydrolysis of polyphosphoinositides with the resulting generation of two messengers: inositol 1,4,5-trisphosphate and 1,2-diacylglycerol.

  13. Subclassification of muscarinic receptors in the heart, urinary bladder and sympathetic ganglia in the pithed rat. Selectivity of some classical agonists.

    PubMed

    van Charldorp, K J; de Jonge, A; Thoolen, M J; van Zwieten, P A

    1985-12-01

    In pithed normotensive rats muscarinic receptors were characterized in heart, urinary bladder and sympathetic ganglia; the selectivity of some classical muscarinic agents for these subtypes was investigated. The potencies in decreasing heart rate, increasing bladder pressure and increasing diastolic blood pressure were measured for the following, intraarterially administered cholinergic agonists: McN-A-343 ([4-m-chlorophenylcarbamoyloxy]-2-butynyltrimethylammonium), pilocarpine, carbachol, oxotremorine, arecoline, acetyl-beta-methylcholine and acetylcholine. The selective M1-antagonist pirenzepine, the mixed M1/M2-antagonist dexetimide and the cardioselective M2-antagonist gallamine were used as tools for identification of the receptors. All data were obtained after intravenous pretreatment with a high dose of atenolol to eliminate tachycardia induced by stimulating sympathetic ganglionic muscarinic receptors. Dexetimide strongly antagonized the bradycardia as well as the increase in bladder pressure induced by pilocarpine, carbachol, oxotremorine, arecoline, acetyl-beta-methylcholine and acetylcholine, whereas pirenzepine was much less effective. Gallamine antagonized the bradycardia, whereas no influence was found on the bladder contraction. Pilocarpine acted as a partial agonist in reducing heart rate as well as in increasing bladder pressure, whereas McN-A-343 was almost ineffective in doses up to 1 mg/kg. The hypertensive response to pilocarpine and carbachol was less pronounced than that produced by McN-A-343. Pirenzepine and dexetimide significantly antagonized the hypertensive response to McN-A-343 and pilocarpine, whereas gallamine was much less effective. The hypertensive response induced by carbachol was totally blocked by hexamethonium. The other agonists used in this study did not produce a significant increase in diastolic blood pressure in doses that produced a maximal effect on heart rate and urinary bladder pressure.(ABSTRACT TRUNCATED AT 250 WORDS

  14. The microwave and millimeter spectrum of ZnCCH (X̃2Σ+): a new zinc-containing free radical.

    PubMed

    Min, J; Halfen, D T; Sun, M; Harris, B; Ziurys, L M

    2012-06-28

    The pure rotational spectrum of the ZnCCH (X̃(2)Σ(+)) radical has been measured using Fourier transform microwave (FTMW) and millimeter direct-absorption methods in the frequency range of 7-260 GHz. This work is the first study of ZnCCH by any type of spectroscopic technique. In the FTMW system, the radical was synthesized in a mixture of zinc vapor and 0.05% acetylene in argon, using a discharge assisted laser ablation source. In the millimeter-wave spectrometer, the molecule was created from the reaction of zinc vapor, produced in a Broida-type oven, with pure acetylene in a dc discharge. Thirteen rotational transitions were recorded for the main species, (64)ZnCCH, and between 4 and 10 for the (66)ZnCCH, (68)ZnCCH, (64)ZnCCD, and (64)Zn(13)C(13)CH isotopologues. The fine structure doublets were observed in all the data, and in the FTMW spectra, hydrogen, deuterium, and carbon-13 hyperfine splittings were resolved. The data have been analyzed with a (2)Σ Hamiltonian, and rotational, spin-rotation, and H, D, and (13)C hyperfine parameters have been established for this radical. From the rotational constants, an r(m) ((1)) structure was determined with r(Zn-C) = 1.9083 Å, r(C-C) = 1.2313 Å, and r(C-H) = 1.0508 Å. The geometry suggests that ZnCCH is primarily a covalent species with the zinc atom singly bonded to the C≡C-H moiety. This result is consistent with the hyperfine parameters, which suggest that the unpaired electron is localized on the zinc nucleus. The spin-rotation constant indicates that an excited (2)Π state may exist ∼19,000 cm(-1) in energy above the ground state.

  15. Electrophysiological properties of lumbar motoneurons in the alpha-chloralose-anesthetized cat during carbachol-induced motor inhibition.

    PubMed

    Xi, M C; Liu, R H; Yamuy, J; Morales, F R; Chase, M H

    1997-07-01

    The present study was undertaken 1) to examine the neuronal mechanisms responsible for the inhibition of spinal cord motoneurons that occurs in alpha-chloralose-anesthetized cats following the microinjection of carbachol into the nucleus pontis oralis (NPO), and 2) to determine whether the inhibitory mechanisms are the same as those that are responsible for the postsynaptic inhibition of motoneurons that is present during naturally occurring active sleep. Accordingly, the basic electrophysiological properties of lumbar motoneurons were examined, with the use of intracellular recording techniques, in cats anesthetized with alpha-chloralose and compared with those present during naturally occurring active sleep. The intrapontine administration of carbachol resulted in a sustained reduction in the amplitude of the spinal cord Ia monosynaptic reflex. Discrete large-amplitude inhibitory postsynaptic potentials (IPSPs), which are only present during the state of active sleep in the chronic cat, were also observed in high-gain recordings from lumbar motoneurons after the injection of carbachol. During carbachol-induced motor inhibition, lumbar motoneurons exhibited a statistically significant decrease in input resistance, membrane time constant and a reduction in the amplitude of the action potential's afterhyperpolarization. In addition, there was a statistically significant increase in rheobase and in the delay between the initial-segment (IS) and somadendritic (SD) portions of the action potential (IS-SD delay). There was a significant increase in the mean motoneuron resting membrane potential (i.e., hyperpolarization). The preceding changes in the electrophysiological properties of motoneurons, as well as the development of discrete IPSPs, indicate that lumbar motoneurons are postsynaptically inhibited after the intrapontine administration of carbachol in cats that are anesthetized with alpha-chloralose. These changes in the electrophysiological properties of lumbar

  16. Axonal transport of muscarinic cholinergic receptors in rat vagus nerve: high and low affinity agonist receptors move in opposite directions and differ in nucleotide sensitivity

    SciTech Connect

    Zarbin, M.A.; Wamsley, J.K.; Kuhar, M.J.

    1982-07-01

    The presence and transport of muscarinic cholinergic binding sites have been detected in the rat vagus nerve. These binding sites accumulate both proximal and distal to ligatures in a time-dependent manner. The results of double ligature and colchicine experiments are compatible with the notion that the anterogradely transported binding sites move by fast transport. Most of the sites accumulating proximal to ligatures bind the agonist carbachol with high affinity, while most of the sites accumulating distally bind carbachol with a low affinity. Also, the receptors transported in the anterograde direction are affected by a guanine nucleotide analogue (GppNHp), while those transported in the retrograde direction are less, or not, affected. The bulk of the sites along the unligated nerve trunk bind carbachol with a low affinity and are less sensitive to GppNHp modulation than the anterogradely transported sites. These results suggest that some receptors in the vagus may undergo axonal transport in association with regulatory proteins and that receptor molecules undergo changes in their binding and regulatory properties during their life cycle. These data also support the notion that the high and low affinity agonist form of the muscarinic receptor represent different modulated forms of a single receptor molecule.

  17. c-fos Expression in mesopontine noradrenergic and cholinergic neurons of the cat during carbachol-induced active sleep: a double-labeling study.

    PubMed

    Yamuy, J; Sampogna, S; Morales, F R; Chase, M H

    1998-01-01

    The interaction of cholinergic and catecholaminergic mechanisms in the mesopontine region has been hypothesized as being critical for the generation and maintenance of active (REM) sleep. To further examine this hypothesis, we sought to determine the pattern of neuronal activation (via c-fos expression) of catecholaminergic and cholinergic neurons in this region during active sleep induced by the pontine microapplication of carbachol (designated as active sleep-carbachol). Accordingly, we used two sets of double-labeling techniques; the first to identify tyrosine hydroxylase-containing neurons (putative catecholaminergic cells) which also express the c-fos protein product Fos, and the second to reveal choline acetyltransferase-containing neurons (putative cholinergic cells) which also express Fos. Compared to control cats, active sleep-carbachol cats exhibited a significantly greater number of Fos-expressing neurons in the dorsolateral region of the pons, which encompasses the locus coeruleus, the lateral pontine reticular formation, the peribrachial nuclei and the latero-dorsal and pedunculo-pontine tegmental nuclei. However, both control and active sleep-carbachol cats exhibited a similar number of catecholaminergic and cholinergic neurons in those regions that expressed Fos (i.e., double-labeled cells). A large number of c-fos-expressing neurons in the active sleep-carbachol cats whose neurotransmitter phenotype was not identified suggests that non-catecholaminergic, non-cholinergic neuronal populations in mesopontine regions are involved in the generation and maintenance of active sleep. The lack of increased c-fos expression in catecholaminergic neurons during active sleep-carbachol confirms and extends previous data that indicate that these cells are silent during active sleep-carbachol and naturally-occurring active sleep. The finding that cholinergic neurons of the dorsolateral pons were not activated either during wakefulness or active sleep-carbachol

  18. c-fos Expression in mesopontine noradrenergic and cholinergic neurons of the cat during carbachol-induced active sleep: a double-labeling study.

    PubMed

    Yamuy, J; Sampogna, S; Morales, F R; Chase, M H

    1998-01-01

    The interaction of cholinergic and catecholaminergic mechanisms in the mesopontine region has been hypothesized as being critical for the generation and maintenance of active (REM) sleep. To further examine this hypothesis, we sought to determine the pattern of neuronal activation (via c-fos expression) of catecholaminergic and cholinergic neurons in this region during active sleep induced by the pontine microapplication of carbachol (designated as active sleep-carbachol). Accordingly, we used two sets of double-labeling techniques; the first to identify tyrosine hydroxylase-containing neurons (putative catecholaminergic cells) which also express the c-fos protein product Fos, and the second to reveal choline acetyltransferase-containing neurons (putative cholinergic cells) which also express Fos. Compared to control cats, active sleep-carbachol cats exhibited a significantly greater number of Fos-expressing neurons in the dorsolateral region of the pons, which encompasses the locus coeruleus, the lateral pontine reticular formation, the peribrachial nuclei and the latero-dorsal and pedunculo-pontine tegmental nuclei. However, both control and active sleep-carbachol cats exhibited a similar number of catecholaminergic and cholinergic neurons in those regions that expressed Fos (i.e., double-labeled cells). A large number of c-fos-expressing neurons in the active sleep-carbachol cats whose neurotransmitter phenotype was not identified suggests that non-catecholaminergic, non-cholinergic neuronal populations in mesopontine regions are involved in the generation and maintenance of active sleep. The lack of increased c-fos expression in catecholaminergic neurons during active sleep-carbachol confirms and extends previous data that indicate that these cells are silent during active sleep-carbachol and naturally-occurring active sleep. The finding that cholinergic neurons of the dorsolateral pons were not activated either during wakefulness or active sleep-carbachol

  19. Ethanolamine utilization in Salmonella typhimurium: nucleotide sequence, protein expression, and mutational analysis of the cchA cchB eutE eutJ eutG eutH gene cluster.

    PubMed

    Stojiljkovic, I; Bäumler, A J; Heffron, F

    1995-03-01

    A fragment of the Salmonella typhimurium ethanolamine utilization operon was cloned and characterized. The 6.3-kb nucleotide sequence encoded six complete open reading frames, termed cchA, cchB, eutE, eutJ, eutG, and eutH. In addition, the nucleotide sequences of two incomplete open reading frames, termed eutX and eutI, were also determined. Comparison of the deduced amino acid sequences and entries in the GenBank database indicated that eutI encodes a phosphate acetyltransferase-like enzyme. The deduced amino acid sequences of the EutE and EutG proteins revealed a significant degree of homology with the Escherichia coli alcohol dehydrogenase AdhE sequence. Mutations in eutE or eutG completely abolished the ability of mutants to utilize ethanolamine as a carbon source and reduced the ability to utilize ethanolamine as a nitrogen source. The product of eutE is most probably an acetaldehyde dehydrogenase catalyzing the conversion of acetaldehyde into acetyl coenzyme A. The product of the eutG gene, an uncommon iron-containing alcohol dehydrogenase, may protect the cell from unconverted acetaldehyde by converting it into an alcohol. The deduced amino acid sequence of cchA resembles that of carboxysome shell proteins from Thiobacillus neapolitanus and Synechococcus sp. as well as that of the PduA product from S. typhimurium. CchA and CchB proteins may be involved in the formation of an intracellular microcompartment responsible for the metabolism of ethanolamine. The hydrophobic protein encoded by the eutH gene possesses some characteristics of bacterial permeases and might therefore be involved in the transport of ethanolamine. Ethanolamine-utilization mutants were slightly attenuated in a mouse model of S. typhimurium infection, indicating that ethanolamine may be an important source of nitrogen and carbon for S. typhimurium in vivo.

  20. Naloxone reduces the amplitude of IPSPs evoked in lumbar motoneurons by reticular stimulation during carbachol-induced motor inhibition.

    PubMed

    Xi, M C; Liu, R H; Yamuy, J; Morales, F R; Chase, M H

    1999-02-20

    During active sleep or carbachol-induced motor inhibition, electrical stimulation of the medullary nucleus reticularis gigantocellularis (NRGc) evoked large amplitude, glycinergic inhibitory postsynaptic potentials (IPSPs) in cat motoneurons. The present study was directed to determine whether these IPSPs, that are specific to the state of active sleep, are modulated by opioid peptides. Accordingly, intracellular recordings were obtained from lumbar motoneurons of acute decerebrate cats during carbachol-induced motor inhibition while an opiate receptor antagonist, naloxone, was microiontophoretically released next to the recorded cells. Naloxone reversibly reduced by 26% the mean amplitude of NRGc-evoked IPSPs (1.9+/-0.2 mV (S.E.M.) vs. 1.4+/-0.2 mV; n=11, control and naloxone, respectively, p<0.05), but had no effect on the other waveform parameters of these IPSPs (e.g., latency-to-onset, latency-to-peak, duration, etc.). The mean resting membrane potential, input resistance and membrane time constant of motoneurons following naloxone ejection were not statistically different from those of the control. These data indicate that opioid peptides have a modulatory effect on NRGc-evoked IPSPs during carbachol-induced motor inhibition. We therefore suggest that endogenous opioid peptides may act as neuromodulators to regulate inhibitory glycinergic synaptic transmission at motoneurons during active sleep. PMID:10082872

  1. Reliable Spectroscopic Constants for CCH-, NH2- and Their Isotopomers from an Accurate Potential Energy Function

    NASA Technical Reports Server (NTRS)

    Lee, Timothy J.; Dateo, Christopher E.; Schwenke, David W.; Chaban, Galina M.

    2005-01-01

    Accurate quartic force fields have been determined for the CCH- and NH2- molecular anions using the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations, CCSD(T). Very large one-particle basis sets have been used including diffuse functions and up through g-type functions. Correlation of the nitrogen and carbon core electrons has been included, as well as other "small" effects, such as the diagonal Born-Oppenheimer correction, and basis set extrapolation, and corrections for higher-order correlation effects and scalar relativistic effects. Fundamental vibrational frequencies have been computed using standard second-order perturbation theory as well as variational methods. Comparison with the available experimental data is presented and discussed. The implications of our research for the astronomical observation of molecular anions will be discussed.

  2. The rotational spectrum of CuCCH(X̃  1Σ+): a Fourier transform microwave discharge assisted laser ablation spectroscopy and millimeter/submillimeter study.

    PubMed

    Sun, M; Halfen, D T; Min, J; Harris, B; Clouthier, D J; Ziurys, L M

    2010-11-01

    The pure rotational spectrum of CuCCH in its ground electronic state (X̃  (1)Σ(+)) has been measured in the frequency range of 7-305 GHz using Fourier transform microwave (FTMW) and direct absorption millimeter/submillimeter methods. This work is the first spectroscopic study of CuCCH, a model system for copper acetylides. The molecule was synthesized using a new technique, discharge assisted laser ablation spectroscopy (DALAS). Four to five rotational transitions were measured for this species in six isotopologues ((63)CuCCH, (65)CuCCH, (63)Cu(13)CCH, (63)CuC(13)CH, (63)Cu(13)C(13)CH, and (63)CuCCD); hyperfine interactions arising from the copper nucleus were resolved, as well as smaller splittings in CuCCD due to deuterium quadrupole coupling. Five rotational transitions were also recorded in the millimeter region for (63)CuCCH and (65)CuCCH, using a Broida oven source. The combined FTMW and millimeter spectra were analyzed with an effective Hamiltonian, and rotational, electric quadrupole (Cu and D) and copper nuclear spin-rotation constants were determined. From the rotational constants, an r(m)(2) structure for CuCCH was established, with r(Cu-C) = 1.8177(6) Å, r(C-C) = 1.2174(6) Å, and r(C-H) = 1.046(2) Å. The geometry suggests that CuCCH is primarily a covalent species with the copper atom singly bonded to the C≡C-H moiety. The copper quadrupole constant indicates that the bonding orbital of this atom may be sp hybridized. The DALAS technique promises to be fruitful in the study of other small, metal-containing molecules of chemical interest.

  3. Signal transduction in insulin secretion: comparison between fuel stimuli and receptor agonists.

    PubMed

    Wollheim, C B; Biden, T J

    1986-01-01

    The initial events in signal transduction in insulin-secreting cells are summarized in FIGURE 8. Both nutrient stimuli, such as glucose and amino acids and the muscarinic agonist carbachol (carbamylcholine) raise [Ca2+]i. Although the rise in [Ca2+]i precedes the stimulation of insulin release, it is not a moment-to-moment regulator of release. The metabolizable fuel stimuli cause Ca2+ influx through voltage-dependent Ca2+ channels following depolarization of the membrane potential. In contrast, carbachol, which does not depolarize, elicits Ptd Ins 4,5-P2 hydrolysis, a reaction catalyzed by phospholipase C. The generation of Ins 1,4,5-P3 in this instance is Ca2+ independent, but appears to involve a GTP-binding protein. However, this protein is not a substrate for pertussis toxin. The levels of Ins 1,4,5-P3, which releases Ca2+ from an ATP-dependent Ca2+ pool of the endoplasmic reticulum, are increased prior to the rise in [Ca2+]i. The mitochondria may take up Ca2+ after large increases in [Ca2+]i. A previously proposed second messenger, arachidonic acid, is much less selective than Ins 1,4,5-P3 in that it releases Ca2+ from mitochondria as well as from the endoplasmic reticulum in a slow and irreversible manner. As Ins 1,4,5-P3 is also generated during glucose stimulation of islets, albeit in a Ca2+-dependent manner, this metabolite could mediate not only the action of carbachol but also contribute to amplifying the [Ca2+]i rise in response to glucose.

  4. Fos and serotonin immunoreactivity in the raphe nuclei of the cat during carbachol-induced active sleep: a double-labeling study.

    PubMed

    Yamuy, J; Sampogna, S; López-Rodríguez, F; Luppi, P H; Morales, F R; Chase, M H

    1995-07-01

    The microinjection of carbachol into the nucleus pontis oralis produces a state which is polygraphically and behaviorally similar to active sleep (rapid eye movement sleep). In the present study, using double-labeling techniques for serotonin and the protein product of c-fos (Fos), we sought to examine whether immunocytochemically identified serotonergic neurons of the raphe nuclei of the cat were activated, as indicated by their expression of c-fos, during this pharmacologically-induced behavioral state (active sleep-carbachol). Compared with control cats, which were injected with saline, active sleep-carbachol cats exhibited a significantly greater number of c-fos-expressing neurons in the raphe dorsalis, magnus and pallidus. Whereas most of the c-fos-expressing neurons in the raphe dorsalis were small, those in the raphe magnus were medium-sized and in the raphe pallidus they were small and medium-sized. The mean number of serotonergic neurons that expressed c-fos (i.e. double-labeled cells) was similar in control and active sleep-carbachol cats. These data indicate that there is an increased number of non-serotonergic, c-fos-expressing neurons in the raphe dorsalis, magnus and pallidus during the carbachol-induced state.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7477901

  5. Rotational Spectrum of Neopentyl Alcohol, (CH_3)_3CCH_2OH

    NASA Astrophysics Data System (ADS)

    Kisiel, Zbigniew; Pszczołkowski, Lech; Xue, Zhifeng; Suhm, Martin A.

    2012-06-01

    The rotational spectrum of neopentyl alcohol (2,2-dimethyl-1-propanol, (CH_3)_3CCH_2OH) has been investigated for the first time. This molecule differs from ethanol only in having the ^tBu group instead of the methyl group, and is likewise anticipated to exhibit two spectroscopic species, with trans and gauche hydroxyl orientation. Quantum chemistry computations predict the trans to be the more stable species. Rotational transitions of both species have now been assigned in supersonic expansion cm-wave FTMW experiment and in room temperature, mm-wave spectra up to 280 GHz. The supersonic expansion measurements with Ar carrier gas confirm that trans is the global minimum species. The trans spectrum is predominantly b-type, while the gauche is predominantly a-type and the frequencies of rotational transitions in both species appear to be perturbed in different ways. The results from effective and from coupled Hamiltonian fits for neopentyl alcohol are presented, and are compared with predictions from ab initio calculations.

  6. Density functional investigations on the (H 2O) n·CCH and (H 2O) n·HCC complexes ( n=1-3)

    NASA Astrophysics Data System (ADS)

    Qu, Zheng-wang; Zhu, Hui; Zhang, Xing-kang; Zhang, Qi-yuan

    2003-01-01

    The electronic structures and energies of (H 2O) n·CCH and (H 2O) n·HCC complexes ( n=1-3) between CCH and water have been theoretically investigated at the UB3LYP/6-311++G(2df,p)//UB3LYP/6-311G(d,p) level. The complexes with n=2-3 are cyclic structures with homodromic hydrogen-bond chain. The (H 2O) n·CCH ( n=1-3) complexes show increasing stabilities towards CCH- or H 2O-eliminations of 2.3, 5.8 and 7.6 kcal/mol and are energetically more stable than the corresponding (H 2O) n·HCC complexes by 0.8, 2.7 and 3.4 kcal/mol, respectively, due to the charge-separation-enhanced hydrogen bonds within (H 2O) n·CCH ( n=2,3). Strong interactions between CCH and (H 2O) 2 and (H 2O) 3 clusters suggest special solvent effects of water on the chemical behavior of unsaturated radicals.

  7. GABAergic neurons of the laterodorsal and pedunculopontine tegmental nuclei of the cat express c-fos during carbachol-induced active sleep.

    PubMed

    Torterolo, P; Yamuy, J; Sampogna, S; Morales, F R; Chase, M H

    2001-02-23

    The laterodorsal and pedunculopontine tegmental nuclei (LDT-PPT) are involved in the generation of active sleep (AS; also called REM or rapid eye movement sleep). Although the LDT-PPT are composed principally of cholinergic neurons that participate in the control of sleep and waking states, the function of the large number of GABAergic neurons that are also located in the LDT-PPT is unknown. Consequently, we sought to determine if these neurons are activated (as indicated by their c-fos expression) during active sleep induced by the microinjection of carbachol into the rostro-dorsal pons (AS-carbachol). Accordingly, immunocytochemical double-labeling techniques were used to identify GABA and Fos protein, as well as choline acetyltransferase (ChAT), in histological sections of the LDT-PPT. Compared to control awake cats, there was a larger number of GABAergic neurons that expressed c-fos during AS-carbachol (31.5+/-6.1 vs. 112+/-15.2, P<0.005). This increase in the number of GABA+Fos+ neurons occurred on the ipsilateral side relative to the injection site; there was a small decrease in GABA+Fos+ cells in the contralateral LDT-PPT. However, the LDT-PPT neurons that exhibited the largest increase in c-fos expression during AS-carbachol were neither GABA+ nor ChAT+ (47+/-22.5 vs. 228.7+/-14.0, P<0.0005). The number of cholinergic neurons that expressed c-fos during AS-carbachol was not significantly different compared to wakefulness. These data demonstrate that, during AS-carbachol, GABAergic as well as an unidentified population of neurons are activated in the LDT-PPT. We propose that these non-cholinergic LDT-PPT neurons may participate in the regulation of active sleep. PMID:11172778

  8. GABAergic neurons of the laterodorsal and pedunculopontine tegmental nuclei of the cat express c-fos during carbachol-induced active sleep.

    PubMed

    Torterolo, P; Yamuy, J; Sampogna, S; Morales, F R; Chase, M H

    2001-02-23

    The laterodorsal and pedunculopontine tegmental nuclei (LDT-PPT) are involved in the generation of active sleep (AS; also called REM or rapid eye movement sleep). Although the LDT-PPT are composed principally of cholinergic neurons that participate in the control of sleep and waking states, the function of the large number of GABAergic neurons that are also located in the LDT-PPT is unknown. Consequently, we sought to determine if these neurons are activated (as indicated by their c-fos expression) during active sleep induced by the microinjection of carbachol into the rostro-dorsal pons (AS-carbachol). Accordingly, immunocytochemical double-labeling techniques were used to identify GABA and Fos protein, as well as choline acetyltransferase (ChAT), in histological sections of the LDT-PPT. Compared to control awake cats, there was a larger number of GABAergic neurons that expressed c-fos during AS-carbachol (31.5+/-6.1 vs. 112+/-15.2, P<0.005). This increase in the number of GABA+Fos+ neurons occurred on the ipsilateral side relative to the injection site; there was a small decrease in GABA+Fos+ cells in the contralateral LDT-PPT. However, the LDT-PPT neurons that exhibited the largest increase in c-fos expression during AS-carbachol were neither GABA+ nor ChAT+ (47+/-22.5 vs. 228.7+/-14.0, P<0.0005). The number of cholinergic neurons that expressed c-fos during AS-carbachol was not significantly different compared to wakefulness. These data demonstrate that, during AS-carbachol, GABAergic as well as an unidentified population of neurons are activated in the LDT-PPT. We propose that these non-cholinergic LDT-PPT neurons may participate in the regulation of active sleep.

  9. A germin-like protein gene (CchGLP) of Capsicum chinense Jacq. is induced during incompatible interactions and displays Mn-superoxide dismutase activity.

    PubMed

    León-Galván, Fabiola; de Jesús Joaquín-Ramos, Ahuizolt; Torres-Pacheco, Irineo; Barba de la Rosa, Ana P; Guevara-Olvera, Lorenzo; González-Chavira, Mario M; Ocampo-Velazquez, Rosalía V; Rico-García, Enrique; Guevara-González, Ramón Gerardo

    2011-01-01

    A germin-like gene (CchGLP) cloned from geminivirus-resistant pepper (Capsicum chinense Jacq. Line BG-3821) was characterized and the enzymatic activity of the expressed protein analyzed. The predicted protein consists of 203 amino acids, similar to other germin-like proteins. A highly conserved cupin domain and typical germin boxes, one of them containing three histidines and one glutamate, are also present in CchGLP. A signal peptide was predicted in the first 18 N-terminal amino acids, as well as one putative N-glycosylation site from residues 44-47. CchGLP was expressed in E. coli and the recombinant protein displayed manganese superoxide dismutase (Mn-SOD) activity. Molecular analysis showed that CchGLP is present in one copy in the C. chinense Jacq. genome and was induced in plants by ethylene (Et) and salicylic acid (SA) but not jasmonic acid (JA) applications in the absence of pathogens. Meanwhile, incompatible interactions with either Pepper golden mosaic virus (PepGMV) or Pepper huasteco yellow vein virus (PHYVV) caused local and systemic CchGLP induction in these geminivirus-resistant plants, but not in a susceptible accession. Compatible interactions with PHYVV, PepGMV and oomycete Phytophthora capsici did not induce CchGLP expression. Thus, these results indicate that CchGLP encodes a Mn-SOD, which is induced in the C. chinense geminivirus-resistant line BG-3821, likely using SA and Et signaling pathways during incompatible interactions with geminiviruses PepGMV and PHYVV.

  10. A Germin-Like Protein Gene (CchGLP) of Capsicum chinense Jacq. Is Induced during Incompatible Interactions and Displays Mn-Superoxide Dismutase Activity

    PubMed Central

    León-Galván, Fabiola; de Jesús Joaquín-Ramos, Ahuizolt; Torres-Pacheco, Irineo; Barba de la Rosa, Ana P.; Guevara-Olvera, Lorenzo; González-Chavira, Mario M.; Ocampo-Velazquez, Rosalía V.; Rico-García, Enrique; Guevara-González, Ramón Gerardo

    2011-01-01

    A germin-like gene (CchGLP) cloned from geminivirus-resistant pepper (Capsicum chinense Jacq. Line BG-3821) was characterized and the enzymatic activity of the expressed protein analyzed. The predicted protein consists of 203 amino acids, similar to other germin-like proteins. A highly conserved cupin domain and typical germin boxes, one of them containing three histidines and one glutamate, are also present in CchGLP. A signal peptide was predicted in the first 18 N-terminal amino acids, as well as one putative N-glycosylation site from residues 44–47. CchGLP was expressed in E. coli and the recombinant protein displayed manganese superoxide dismutase (Mn-SOD) activity. Molecular analysis showed that CchGLP is present in one copy in the C. chinense Jacq. genome and was induced in plants by ethylene (Et) and salicylic acid (SA) but not jasmonic acid (JA) applications in the absence of pathogens. Meanwhile, incompatible interactions with either Pepper golden mosaic virus (PepGMV) or Pepper huasteco yellow vein virus (PHYVV) caused local and systemic CchGLP induction in these geminivirus-resistant plants, but not in a susceptible accession. Compatible interactions with PHYVV, PepGMV and oomycete Phytophthora capsici did not induce CchGLP expression. Thus, these results indicate that CchGLP encodes a Mn-SOD, which is induced in the C. chinense geminivirus-resistant line BG-3821, likely using SA and Et signaling pathways during incompatible interactions with geminiviruses PepGMV and PHYVV. PMID:22174599

  11. Electrophysiological characterization of neurons in the dorsolateral pontine REM sleep induction zone of the rat: intrinsic membrane properties and responses to carbachol and orexins

    PubMed Central

    Brown§, Ritchie E.; Winston, Stuart; Basheer, Radhika; Thakkar, Mahesh M; McCarley, Robert W.

    2006-01-01

    Pharmacological, lesion and single-unit recording techniques in several animal species have identified a region of the pontine reticular formation (Subcoeruleus, SubC) just ventral to the locus coeruleus as critically involved in the generation of rapid-eye-movement (REM) sleep. However, the intrinsic membrane properties and responses of SubC neurons to neurotransmitters important in REM sleep control, such as acetylcholine and orexins/hypocretins, have not previously been examined in any animal species and thus were targeted in this study. We obtained whole-cell patch-clamp recordings from visually identified SubC neurons in rat brain slices in vitro. Two groups of large neurons (mean diameter 30 and 27μm) were tentatively identified as cholinergic (rostral SubC) and noradrenergic (caudal SubC) neurons. SubC reticular neurons (non-cholinergic, non-noradrenergic) showed a medium-sized depolarizing sag during hyperpolarizing current pulses and often had a rebound depolarization (low-threshold spike, LTS). During depolarizing current pulses they exhibited little adaptation and fired maximally at 30–90 Hz. Those SubC reticular neurons excited by carbachol (n=27) fired spontaneously at 6 Hz, often exhibited a moderately sized LTS, and varied widely in size (17–42 μm). Carbachol-inhibited SubC reticular neurons were medium-sized (15–25 μm) and constituted two groups. The larger group (n=22) was silent at rest and possessed a prominent LTS and associated 1–4 action potentials. The second, smaller group (n=8) had a delayed return to baseline at the offset of hyperpolarizing pulses. Orexins excited both carbachol excited and carbachol inhibited SubC reticular neurons. SubC reticular neurons had intrinsic membrane properties and responses to carbachol similar to those described for other reticular neurons but a larger number of carbachol inhibited neurons were found (> 50 %), the majority of which demonstrated a prominent LTS and may correspond to PGO-on neurons

  12. Electrophysiological characterization of neurons in the dorsolateral pontine rapid-eye-movement sleep induction zone of the rat: Intrinsic membrane properties and responses to carbachol and orexins.

    PubMed

    Brown, R E; Winston, S; Basheer, R; Thakkar, M M; McCarley, R W

    2006-12-01

    Pharmacological, lesion and single-unit recording techniques in several animal species have identified a region of the pontine reticular formation (subcoeruleus, SubC) just ventral to the locus coeruleus as critically involved in the generation of rapid-eye-movement (REM) sleep. However, the intrinsic membrane properties and responses of SubC neurons to neurotransmitters important in REM sleep control, such as acetylcholine and orexins/hypocretins, have not previously been examined in any animal species and thus were targeted in this study. We obtained whole-cell patch-clamp recordings from visually identified SubC neurons in rat brain slices in vitro. Two groups of large neurons (mean diameter 30 and 27 mum) were tentatively identified as cholinergic (rostral SubC) and noradrenergic (caudal SubC) neurons. SubC reticular neurons (non-cholinergic, non-noradrenergic) showed a medium-sized depolarizing sag during hyperpolarizing current pulses and often had a rebound depolarization (low-threshold spike, LTS). During depolarizing current pulses they exhibited little adaptation and fired maximally at 30-90 Hz. Those SubC reticular neurons excited by carbachol (n=27) fired spontaneously at 6 Hz, often exhibited a moderately sized LTS, and varied widely in size (17-42 mum). Carbachol-inhibited SubC reticular neurons were medium-sized (15-25 mum) and constituted two groups. The larger group (n=22) was silent at rest and possessed a prominent LTS and associated one to four action potentials. The second, smaller group (n=8) had a delayed return to baseline at the offset of hyperpolarizing pulses. Orexins excited both carbachol excited and carbachol inhibited SubC reticular neurons. SubC reticular neurons had intrinsic membrane properties and responses to carbachol similar to those described for other reticular neurons but a larger number of carbachol inhibited neurons were found (>50%), the majority of which demonstrated a prominent LTS and may correspond to pontine

  13. Pharmacological estimation of agonist affinity: detection of errors that may be caused by the operation of receptor isomerisation or ternary complex mechanisms.

    PubMed

    Leff, P; Harper, D; Dainty, I A; Dougall, I G

    1990-09-01

    1. Recent theoretical studies have questioned the pharmacological estimation of agonist affinity. They showed that when receptor isomerisation or ternary complex mechanisms operate, the receptor inactivation method can substantially overestimate affinity, whereas methods for partial agonist analysis are more accurate. We previously suggested that the operation of such mechanisms and therefore the presence of errors could be detected by analysing the same partial agonist by the receptor inactivation and comparative methods. This paper describes the practical application of this test. 2. The ternary complex mechanism was simulated for a partial agonist under various conditions relating receptor (R) and transducer (T) concentrations, one of which also corresponds to the receptor isomerisation mechanism. The theoretical data so generated were then analysed by the inactivation and comparative methods to quantify the magnitude of error of affinity estimation that could occur. 3. This analysis showed that for a partial agonist with approximately 85% of the activity of a full agonist, the inactivation method could produce an affinity (pKA) estimate up to 0.7 log10 units higher than that produced by the comparative method. This difference would occur when the total receptor concentration ([R0]) is less than or equal to the total transducer concentration ([T0]). It also showed that the overestimation of affinity by the inactivation method was accompanied by drastic overestimation of Em, the maximal effect parameter. 4. The test was then exemplified using the muscarinic receptor system in the guinea-pig isolated left atrial preparation, where there is evidence that a ternary complex mechanism operates. The test agonist was pilocarpine, which produced on average 83% of the activity of the full agonist, carbachol. Pilocarpine was analysed in comparison with carbachol and by receptor inactivation in the same tissue resulting in small and statistically insignificant differences

  14. A natural history of "agonist".

    PubMed

    Russo, Ruth

    2002-01-01

    This paper constructs a brief history of the biochemical term agonist by exploring the multiple meanings of the root agôn in ancient Greek literature and describing how agonist first appeared in the scientific literature of the 20th century in the context of neurophysiologists' debates about the existence and properties of cellular receptors. While the narrow scientific definition of agonist may appear colorless and dead when compared with the web of allusions spun by the ancient Greek agôn, the scientific power and creativity of agonist actually resides precisely in its exact, restricted meaning for biomedical researchers.

  15. Observations of Methane Concentration and d13C-CH4 in the East Siberian Sea Waters

    NASA Astrophysics Data System (ADS)

    Shcherbakova, K.; Steinbach, J.; Holmstrand, H.; Kosmach, D.; Panova, E.; Gustafsson, O.; Semiletov, I. P.; Shakhova, N. E.; Sapart, C. J.

    2015-12-01

    Large amounts of methane (CH4) are stored beneath the East Siberian Arctic Shelf (ESAS) within subsea permafrost, as gas hydrates or free gas underneath. With the ongoing climate warming in that region, there is potential for significant release of CH4 to the water column and eventually to the atmosphere. Over a decade of shipboard expeditions has shown enhanced CH4 levels in large parts of the ESAS waters, but we still lack knowledge on which pools are responsible for the releases, as well release mechanisms and removal processes in the water column. Here we show dissolved methane concentration and d13C-CH4 data from water column profiles along a transect across the outer East Siberian Sea, ranging from 140°E to 170°E, taken during the SWERUS-C3 expedition in summer 2014. Elevated CH4 levels were observed throughout the transect; reaching a maximum value of 716nM and a median of 30nM. Due to ice cover in large parts, concentration maxima were mainly located close to the surface or around the picnocline, with the exception of bottom maximum close to a seep area around 160 °N. Initial results for d13C-CH4 range from -60 to -47 per mille vs VPDB.

  16. Unexpected Generation and Observation of a T-Shaped Complex of H_{2}C_{2}\\cdotsAgCCH

    NASA Astrophysics Data System (ADS)

    Walker, N. R.; Stephens, S. L.; Mizukami, W.; Tew, D. P.; Legon, A. C.

    2013-06-01

    An experiment to probe species generated within a supersonically-expanding jet consisting of SF_{6}, Ag, C_{2}H_{2} and argon by broadband rotational spectroscopy revealed the existence of a T-shaped complex of hitherto unknown origin. Empirical tests revealed that this complex requires the presence of C_{2}H_{2} and Ag within the gas sample. While the intensity of the associated transitions are enhanced by the presence of SF_{6}, theoretical calculations and empirical tests implied that the identified complex is H_{2}C_{2}\\cdotsAgCCH rather than the original target of the experiment, H_{2}C_{2}\\cdotsAgF. This deduction is now supported by evidence acquired through experiments exploiting ^{13}C-enriched isotopic samples. Transitions have been assigned for the H_{2}^{13}C_{2}\\cdotsAg^{13}C^{13}CH isotopologue. Data acquired from each isotopologue allows determination of the rotational constants (B}_{0}, C}_{0}) and centrifugal distortion constant, Δ_J}. The data are consistent with a T-shaped complex in which the Ag atom of AgCCH binds to electrons within the {π}-orbitals of ethyne. Preliminary determinations of bond lengths will be presented. Experiments are in progress to measure the spectra of deuterated isotopologues.

  17. In-plane bidimensional stripes in thin films of CCH-PCH mixtures: possible nucleation of a tilted smectic phase

    NASA Astrophysics Data System (ADS)

    Pikin, Sergei A.; Torgova, Sofia I.; Strigazzi, Alfredo

    1996-01-01

    Spontaneous in-plane bidimensional stripes are predicted to appear in thin films of tilted smectic liquid crystals, due to flexopolarization, provided the flexoelectric coefficients are great enough, as in several smectic C's. The two periodicities arise in orthogonal directions. In the presence of free ions, the charge distributions becomes also modulated in-plane, partially masking the direct flexopolarization influence. Both effective periods are of the order of 10 micrometers . The optical observations were performed on mixtures of trans-4-(trans-4'-n- amylcyclohexyl) cyclohexanecarboxylic acid (CCH) and of 4-(trans-4'-n-amylcyclohexyl) benzoic acid (PCH). Both pure compounds exhibit only a nematic phase, the first between 224 degree(s)C and 243 degree(s)C, and the second one between 180 degree(s)C and 265 degree(s)C. The experimental data are consistent with the present model, suggesting that, for certain CCH/PCH ratios less than 30%, a tilted smectic phase is nucleated close to the melting point.

  18. δ(13)C-CH4 reveals CH4 variations over oceans from mid-latitudes to the Arctic.

    PubMed

    Yu, Juan; Xie, Zhouqing; Sun, Liguang; Kang, Hui; He, Pengzhen; Xing, Guangxi

    2015-01-01

    The biogeochemical cycles of CH4 over oceans are poorly understood, especially over the Arctic Ocean. Here we report atmospheric CH4 levels together with δ(13)C-CH4 from offshore China (31°N) to the central Arctic Ocean (up to 87°N) from July to September 2012. CH4 concentrations and δ(13)C-CH4 displayed temporal and spatial variation ranging from 1.65 to 2.63 ppm, and from -50.34% to -44.94% (mean value: -48.55 ± 0.84%), respectively. Changes in CH4 with latitude were linked to the decreasing input of enriched δ(13)C and chemical oxidation by both OH and Cl radicals as indicated by variation of δ(13)C. There were complex mixing sources outside and inside the Arctic Ocean. A keeling plot showed the dominant influence by hydrate gas in the Nordic Sea region, while the long range transport of wetland emissions were one of potentially important sources in the central Arctic Ocean. Experiments comparing sunlight and darkness indicate that microbes may also play an important role in regional variations. PMID:26323236

  19. δ13C-CH4 reveals CH4 variations over oceans from mid-latitudes to the Arctic

    PubMed Central

    Yu, Juan; Xie, Zhouqing; Sun, Liguang; Kang, Hui; He, Pengzhen; Xing, Guangxi

    2015-01-01

    The biogeochemical cycles of CH4 over oceans are poorly understood, especially over the Arctic Ocean. Here we report atmospheric CH4 levels together with δ13C-CH4 from offshore China (31°N) to the central Arctic Ocean (up to 87°N) from July to September 2012. CH4 concentrations and δ13C-CH4 displayed temporal and spatial variation ranging from 1.65 to 2.63 ppm, and from −50.34% to −44.94% (mean value: −48.55 ± 0.84%), respectively. Changes in CH4 with latitude were linked to the decreasing input of enriched δ13C and chemical oxidation by both OH and Cl radicals as indicated by variation of δ13C. There were complex mixing sources outside and inside the Arctic Ocean. A keeling plot showed the dominant influence by hydrate gas in the Nordic Sea region, while the long range transport of wetland emissions were one of potentially important sources in the central Arctic Ocean. Experiments comparing sunlight and darkness indicate that microbes may also play an important role in regional variations. PMID:26323236

  20. Millimeter-wave spectroscopy of CrC (X(3)Σ(-)) and CrCCH (X̃ (6)Σ(+)): Examining the chromium-carbon bond.

    PubMed

    Min, J; Ziurys, L M

    2016-05-14

    Pure rotational spectroscopy of the CrC (X(3)Σ(-)) and CrCCH (X̃ (6)Σ(+)) radicals has been conducted using millimeter/sub-millimeter direct absorption methods in the frequency range 225-585 GHz. These species were created in an AC discharge of Cr(CO)6 and either methane or acetylene, diluted in argon. Spectra of the CrCCD were also recorded for the first time using deuterated acetylene as the carbon precursor. Seven rotational transitions of CrC were measured, each consisting of three widely spaced, fine structure components, arising from spin-spin and spin-rotation interactions. Eleven rotational transitions were recorded for CrCCH and five for CrCCD; each transition in these cases was composed of a distinct fine structure sextet. These measurements confirm the respective (3)Σ(-) and (6)Σ(+) ground electronic states of these radicals, as indicated from optical studies. The data were analyzed using a Hund's case (b) Hamiltonian, and rotational, spin-spin, and spin-rotation constants have been accurately determined for all three species. The spectroscopic parameters for CrC were significantly revised from previous optical work, while those for CrCCH are in excellent agreement; completely new constants were established for CrCCD. The chromium-carbon bond length for CrC was calculated to be 1.631 Å, while that in CrCCH was found to be rCr-C = 1.993 Å - significantly longer. This result suggests that a single Cr-C bond is present in CrCCH, preserving the acetylenic structure of the ligand, while a triple bond exists in CrC. Analysis of the spin constants suggests that CrC has a nearby excited (1)Σ(+) state lying ∼16 900 cm(-1) higher in energy, and CrCCH has a (6)Π excited state with E ∼ 4800 cm(-1).

  1. Millimeter-wave spectroscopy of CrC (X3Σ-) and CrCCH (X ˜ 6Σ+): Examining the chromium-carbon bond

    NASA Astrophysics Data System (ADS)

    Min, J.; Ziurys, L. M.

    2016-05-01

    Pure rotational spectroscopy of the CrC (X3Σ-) and CrCCH (X ˜ 6Σ+) radicals has been conducted using millimeter/sub-millimeter direct absorption methods in the frequency range 225-585 GHz. These species were created in an AC discharge of Cr(CO)6 and either methane or acetylene, diluted in argon. Spectra of the CrCCD were also recorded for the first time using deuterated acetylene as the carbon precursor. Seven rotational transitions of CrC were measured, each consisting of three widely spaced, fine structure components, arising from spin-spin and spin-rotation interactions. Eleven rotational transitions were recorded for CrCCH and five for CrCCD; each transition in these cases was composed of a distinct fine structure sextet. These measurements confirm the respective 3Σ- and 6Σ+ ground electronic states of these radicals, as indicated from optical studies. The data were analyzed using a Hund's case (b) Hamiltonian, and rotational, spin-spin, and spin-rotation constants have been accurately determined for all three species. The spectroscopic parameters for CrC were significantly revised from previous optical work, while those for CrCCH are in excellent agreement; completely new constants were established for CrCCD. The chromium-carbon bond length for CrC was calculated to be 1.631 Å, while that in CrCCH was found to be rCr—C = 1.993 Å — significantly longer. This result suggests that a single Cr—C bond is present in CrCCH, preserving the acetylenic structure of the ligand, while a triple bond exists in CrC. Analysis of the spin constants suggests that CrC has a nearby excited 1Σ+ state lying ˜16 900 cm-1 higher in energy, and CrCCH has a 6Π excited state with E ˜ 4800 cm-1.

  2. Long-term data on δ13C-CH4 emissions elucidate drivers of CH4 metabolism in temperate and northern wetlands

    NASA Astrophysics Data System (ADS)

    McCalley, C. K.; Shorter, J. H.; Crill, P. M.; Hodgkins, S. B.; Chanton, J.; Saleska, S. R.; Varner, R. K.

    2015-12-01

    Methane flux from wetlands is both a critical component of the global CH4 budget, and highly sensitive to global climate change. Gaps in our knowledge of the biological processes that underlie CH4 fluxes from natural ecosystems limit our ability to scale flux estimates as well as predict future emissions. To address these gaps, we used quantum cascade laser technology linked to automated chambers to quantify the isotopic composition of CH4 fluxes from a high latitude (68° N) wetland underlain by discontinuous permafrost (Stordalen Mire, Sweden) and a temperate wetland (43° N) undergoing shrub encroachment (Sallie's Fen, NH). Changes in plant communities and hydrology during permafrost thaw result in both large increases in CH4 emissions as well as shifts in the CH4 production pathway, from hydrogenotrophic to increasingly acetoclastic mechanisms. In contrast, shrub encroachment that replaces sedge species in the temperate wetland reduces CH4 emissions, but doesn't effect δ 13C-CH4, with predominantly acetoclastic production occurring across plant communities. Multi-year data sets identify temperature and hydrologic variability as key contributors to annual and interannual patterns in δ 13C-CH4. Fully-thawed fens at Stordalen had consistent δ13C-CH4 across years, with an annual pattern suggestive of more hydrogenotrophic production early and late in the growing season. In contrast, intermediate-thaw sites, where the water table was more dynamic, had large variations in δ13C-CH4 across years. At Sallie's Fen, patterns in δ13C-CH4 suggest an abrupt shift in CH4 transport and metabolism at the beginning of the growing season and then more stable δ13C-CH4 during the growing season. Together these results provide insights into how plant communities and variable environmental conditions interact to influence the microbial metabolisms that drive CH4 production and consumption in diverse wetland ecosystems.

  3. Differences in time to peak carbachol-induced contractions between circular and longitudinal smooth muscles of mouse ileum.

    PubMed

    Azuma, Yasu-Taka; Samezawa, Nanako; Nishiyama, Kazuhiro; Nakajima, Hidemitsu; Takeuchi, Tadayoshi

    2016-01-01

    The muscular layer in the GI tract consists of an inner circular muscular layer and an outer longitudinal muscular layer. Acetylcholine (ACh) is the representative neurotransmitter that causes contractions in the gastrointestinal tracts of most animal species. There are many reports of muscarinic receptor-mediated contraction of longitudinal muscles, but few studies discuss circular muscles. The present study detailed the contractile response in the circular smooth muscles of the mouse ileum. We used small muscle strips (0.2 mm × 1 mm) and large muscle strips (4 × 4 mm) isolated from the circular and longitudinal muscle layers of the mouse ileum to compare contraction responses in circular and longitudinal smooth muscles. The time to peak contractile responses to carbamylcholine (CCh) were later in the small muscle strips (0.2 × 1 mm) of circular muscle (5.7 min) than longitudinal muscles (0.4 min). The time to peak contractile responses to CCh in the large muscle strips (4 × 4 mm) were also later in the circular muscle (3.1 min) than the longitudinal muscle (1.4 min). Furthermore, a muscarinic M2 receptor antagonist and gap junction inhibitor significantly delayed the time to peak contraction of the large muscle strips (4 × 4 mm) from the circular muscular layer. Our findings indicate that muscarinic M2 receptors in the circular muscular layer of mouse ileum exert a previously undocumented function in gut motility via the regulation of gap junctions.

  4. Determination of mass changes in phosphatidylinositol 4,5-bisphosphate and evidence for agonist-stimulated metabolism of inositol 1,4,5-trisphosphate in airway smooth muscle.

    PubMed Central

    Chilvers, E R; Batty, I H; Challiss, R A; Barnes, P J; Nahorski, S R

    1991-01-01

    Stimulation of muscarinic receptors in bovine tracheal smooth muscle (BTSM) causes a sustained increase in muscle tone, but a transient increase in the second messenger Ins(1,4,5)P3. To examine whether this brief increase in Ins(1,4,5)P3 mass results from transient formation or is due to agonist-stimulation of Ins(1,4,5)P3 metabolism, we have studied the relationship between mass changes in PtdIns(4,5)P2 and Ins(1,4,5)P3 accumulation, and changes in [3H]InsP3, [3H]PtdIns, [3H]PtdInsP1 and [3H]PtdInsP2 in carbachol-stimulated myo-[3H]inositol-prelabelled BTSM slices. Carbachol (0.1 mM) caused a rapid transient increase in Ins(1,4,5)P3 concentration (basal, 12.9 +/- 0.8 pmol/mg of protein; 5 s carbachol treatment, 27.1 +/- 1.5 pmol/mg of protein), with values returning to basal levels by 30 s, but a sustained accumulation of total [3H]InsP3s, with [3H]Ins(1,3,4)P3 being the predominant isomer present at later time points. In contrast, PtdIns(4,5)P2 mass, determined by radioreceptor assay of Ins(1,4,5)P3 in desalted alkaline hydrolysates of acidified chloroform/methanol tissue extracts, declined rapidly (basal, 941 +/- 22 pmol/mg of protein; 120 s carbachol, 365 +/- 22 pmol/mg of protein; t1/2 14 s) and remained at this new steady-state level for at least 20 min in the continued presence of carbachol. Addition of 10 microM-atropine 2 min after carbachol caused a prompt return of PtdIns(4,5)P2 concentration to prestimulated values (t1/2 210 s). Ongoing resynthesis of PtdIns(4,5)P2 after carbachol stimulation was demonstrated in [3H]inositol-labelled tissue by observing a persistent increase in the specific radioactivity of [3H]PtdInsP2, shown to be exclusively [3H]PtdIns(4,5)P2, over a 10 min period. These findings strongly suggest the occurrence of persistent receptor-mediated increases in PtdIns(4,5)P2 hydrolysis and Ins(1,4,5)P3 formation which, in conjunction with the transient accumulation of Ins(1,4,5)P3 observed, provide evidence that regulation of the

  5. Regulation of muscarinic acetylcholine receptors in cultured guinea pig pancreatic acini

    SciTech Connect

    Hootman, S.R.; Brown, M.E.; Williams, J.A.; Logsdon, C.D.

    1986-07-01

    Regulation of muscarinic receptors in cultured guinea pig pancreatic acini was investigated by assessing the effects of cholinergic agonists on binding of (N-methyl-TH)scopolamine ((TH)NMS) and on amylase release. Freshly dispersed acini bound (TH)NMS with a K/sub d/ of 74 pM and a maximal binding level (B/sub max/) of 908 fmol/mg DNA. Carbachol (CCh) stimulated amylase secretion and inhibited (TH)NMS binding. Incubation of acini for 30 min with 0.1 mM CCh decreased the subsequent efficacy of CCh in stimulating amylase release by threefold but had no effect on its potency. In contrast, amylase release in response to cholecystokinin octapeptide (CCK-8) was not altered by CCh preincubation. (TH)NMS binding to acini was decreased only 15-20% after 30-min incubation with CCh. However, culture of acini with 0.1 mM CCh decreased (TH)NMS binding by 50% at 3-4 h and by 85-90% at 24 h. This decrease was attributable primarily to a reduction in B/sub max/ (TH)NMS binding also was decreased to a similar extent by the cholinergic agonists bethanechol and methacholine but not by other secretagogues. The decrease in antagonist binding induced by CCh was dose dependent, with the IC50, 5.8 M, approximating the EC50 for amylase release, 4.3 M. Cultured of acini for 24 h with CCh abolished subsequent amylase release in response to CCh but not to CCK-8. The results indicate that muscarinic receptor turnover in the pancreatic acinus is regulated by receptor activation and that both a decease in receptor numbers and sensitivity to agonists follows prolonged cholinergic agonist exposure.

  6. Changes in the contractile responses to carbachol and in the inhibitory effects of verapamil and nitrendipine on isolated smooth muscle preparations from rats subchronically exposed to Pb2+ and Zn2+.

    PubMed

    Vassilev, P P; Venkova, K; Pencheva, N; Radomirov, R; Staneva-Stoytcheva, D

    1994-01-01

    Male Wistar rats were exposed to Pb2+ or Zn2+ and to Pb2+ + Zn2+, receiving Pb(CH3COO)2 or/and ZnSO4 with drinking water for 30 days. Cumulative concentration-effect curves for carbachol were obtained in ileum and trachea isolated from control and heavy metal-treated rats. The effect of the Ca2+ channel blockers on the carbachol-induced contractions was studied by addition of increasing concentrations of verapamil or nitrendipine to the bath solution 20 min. prior to carbachol. The results showed that exposure of rats to heavy metals in doses which did not change the body weight and behaviour, altered the contractile responses to carbachol. The sensitivity to carbachol was higher in preparations from the ileum of Zn(2+)-exposed rats as compared to controls, while a tendency towards decreasing this sensitivity was observed in ileal preparations from Pb(2+)-treated animals. The concentration-effect curves for carbachol in ileal preparations from Pb2+ + Zn(2+)-treated rats did not differ from those in the preparations from untreated rats. The inhibitory effect of the Ca2+ channel blockers on the contractility of ileal and tracheal preparations from treated rats was weaker as compared to that in controls.

  7. Characterization and agonist regulation of muscarinic ([3H]N-methyl scopolamine) receptors in isolated ventricular myocytes from rat.

    PubMed

    Horackova, M; Robinson, B; Wilkinson, M

    1990-11-01

    Cell surface muscarinic cholinergic receptors have been characterized and quantified for the first time, in intact, isolated adult rat cardiomyocytes. The cells were previously established as functionally fully compatible with cellular responses in intact cardiac tissue. The specific binding of the hydrophilic radioligand, [3H]-NMS, (N-methyl-[3H]-scopolamine methylchloride) was found to be stereo-specific, saturable, reversible and of high affinity. Binding of [3H]-NMS demonstrated appropriate drug specificity and was positively correlated with increasing cell concentrations. Bmax for [3H]-NMS binding to ventricular myocytes, enzymatically dissociated from adult male rats, was 15.8 +/- 1.03 fmol/25 x 10(3) cells (at 4 degrees C) and KD was 0.27 +/- 0.05 nM (n = 14). Binding assays performed at a higher incubation temperature (30 degrees C) yielded a higher Bmax value (22.1 +/- 1.6 fmol/25 x 10(3) cells; n = 11; P less than 0.005 vs. Bmax at 4 degrees C) but an unchanged KD (0.23 +/- 0.06 nM). Pretreatment of myocytes with the muscarinic agonist carbachol (1 mM) at 37 degrees C resulted in a reduction (down-regulation) in specific binding of the hydrophilic ligand [3H]-NMS. The magnitude of this reduction and its rate of recovery were dependent on the time of the exposure to carbachol. Exposures of 30-60 min elicited down-regulated by 35% (Bmax = 14.29 +/- 1.66 changed to 9.5 +/- 1.79 fmol/25 x 10(3) cells, without change in KD P less than 0.01, n = 4). The down-regulation of the muscarinic receptors by carbachol was insensitive to application of bacitracin - an inhibitor of endocytosis. On the other hand preincubation with 10(-9)M atropine, a muscarinic antagonist, hindered the agonist-induced receptor "loss" from the cell surface confirming the muscarinic nature of these receptors. We conclude that our preparation of intact, isolated ventricular cardiomyocytes is ideally suited for the study of cell surface muscarinic receptor regulation under physiological and

  8. Characterization and agonist regulation of muscarinic ([3H]N-methyl scopolamine) receptors in isolated ventricular myocytes from rat.

    PubMed

    Horackova, M; Robinson, B; Wilkinson, M

    1990-11-01

    Cell surface muscarinic cholinergic receptors have been characterized and quantified for the first time, in intact, isolated adult rat cardiomyocytes. The cells were previously established as functionally fully compatible with cellular responses in intact cardiac tissue. The specific binding of the hydrophilic radioligand, [3H]-NMS, (N-methyl-[3H]-scopolamine methylchloride) was found to be stereo-specific, saturable, reversible and of high affinity. Binding of [3H]-NMS demonstrated appropriate drug specificity and was positively correlated with increasing cell concentrations. Bmax for [3H]-NMS binding to ventricular myocytes, enzymatically dissociated from adult male rats, was 15.8 +/- 1.03 fmol/25 x 10(3) cells (at 4 degrees C) and KD was 0.27 +/- 0.05 nM (n = 14). Binding assays performed at a higher incubation temperature (30 degrees C) yielded a higher Bmax value (22.1 +/- 1.6 fmol/25 x 10(3) cells; n = 11; P less than 0.005 vs. Bmax at 4 degrees C) but an unchanged KD (0.23 +/- 0.06 nM). Pretreatment of myocytes with the muscarinic agonist carbachol (1 mM) at 37 degrees C resulted in a reduction (down-regulation) in specific binding of the hydrophilic ligand [3H]-NMS. The magnitude of this reduction and its rate of recovery were dependent on the time of the exposure to carbachol. Exposures of 30-60 min elicited down-regulated by 35% (Bmax = 14.29 +/- 1.66 changed to 9.5 +/- 1.79 fmol/25 x 10(3) cells, without change in KD P less than 0.01, n = 4). The down-regulation of the muscarinic receptors by carbachol was insensitive to application of bacitracin - an inhibitor of endocytosis. On the other hand preincubation with 10(-9)M atropine, a muscarinic antagonist, hindered the agonist-induced receptor "loss" from the cell surface confirming the muscarinic nature of these receptors. We conclude that our preparation of intact, isolated ventricular cardiomyocytes is ideally suited for the study of cell surface muscarinic receptor regulation under physiological and

  9. Diminished agonist-stimulated inositol trisphosphate generation blocks stimulus-secretion coupling in mouse pancreatic acini during diet-induced experimental pancreatitis

    SciTech Connect

    Powers, R.E.; Saluja, A.K.; Houlihan, M.J.; Steer, M.L.

    1986-05-01

    Young female mice fed a choline-deficient, ethionine-supplemented (CDE) diet rapidly develop acute hemorrhagic pancreatitis. We have observed that pancreatic acini prepared from these mice are unable to secrete amylase in response to addition of the cholinergic agonist carbachol, although they retain the ability to secrete amylase in response to the Ca2+ ionophore A23187. The CDE diet does not alter the binding characteristics (Kd or the maximal number of binding sites) for muscarinic cholinergic receptors as tested using the antagonist (/sup 3/H)N-methylscopolamine nor the competition for this binding by carbachol. Addition of carbachol to acini prepared from mice fed the CDE diet does not result in as marked an increase in cytosolic free Ca2+ levels as that noted in control samples (evaluated using quin2 fluorescence). These observations indicate that the CDE diet interferes with stimulus-secretion coupling in mouse pancreatic acini at a step subsequent to hormone-receptor binding and prior to Ca2+ release. This conclusion is confirmed by our finding that the hormone-stimulated generation of (/sup 3/H)inositol phosphates (inositol trisphosphate, inositol bisphosphate, and inositol monophosphate) from acini labeled with (/sup 3/H)myoinositol is markedly reduced in acini prepared from mice fed the CDE diet. This reduction is not due to a decrease in phosphatidylinositol-4,5-bisphosphate. This communication represents the first report of a system in which a blockade of inositol phosphate generation can be related to a physiologic defect and pathologic lesion.

  10. Agonist-trafficking and hallucinogens.

    PubMed

    González-Maeso, Javier; Sealfon, Stuart C

    2009-01-01

    Seven transmembrane domain receptors, also termed G protein-coupled receptors (GPCRs), represent the most common molecular target for therapeutic drugs. The generally accepted pharmacological model for GPCR activation is the ternary complex model, in which GPCRs exist in a dynamic equilibrium between the active and inactive conformational states. However, the demonstration that different agonists sometimes elicit a different relative activation of two signaling pathways downstream of the same receptor has led to a revision of the ternary complex model. According to this agonist- trafficking model, agonists stabilize distinct activated receptor conformations that preferentially activate specific signaling pathways. Hallucinogenic drugs and non-hallucinogenic drugs represent an attractive experimental system with which to study agonist-trafficking of receptor signaling. Thus many of the behavioral responses induced by hallucinogenic drugs, such as lysergic acid diethylamide (LSD), psilocybin or mescaline, depend on activation of serotonin 5-HT(2A) receptors (5-HT2ARs). In contrast, this neuropsychological state in humans is not induced by closely related chemicals, such as lisuride or ergotamine, despite their similar in vitro activity at the 5-HT2AR. In this review, we summarize the current knowledge, as well as unresolved questions, regarding agonist-trafficking and the mechanism of action of hallucinogenic drugs.

  11. Theoretical High-Resolution Spectroscopy Beyond Ccsd(t): the Interstellar Anions CN-, CCH-, C3N-, and C4H-

    NASA Astrophysics Data System (ADS)

    Botschwina, Peter; Schröder, Benjamin; Sebald, Peter; Oswald, Rainer

    2014-06-01

    Using extended coupled cluster methods well beyond fc-CCSD(T), spectroscopic properties of several molecular anions of astrochemical interest have been calculated. Excellent agreement with MW data is observed for CN-, CCH-, C3N-, and C4H- and accurate equilibrium structures are presented for all four species. The results for CCH- are superior to recent theoretical results of Huang and Lee and confirm the quality of our earlier predictions. The new calculations predict ν_1 = 3209.3 cm-1, ν_2 (band origin) = 510.0 cm-1, and ν_3 = 1804.4 cm-1, estimated errors not exceeding 1 cm-1. X. Huang, T. J. Lee J. Chem. Phys. 2009, {131}, 104301. M. Mladenović, P. Botschwina, P. Sebald, S. Carter, Theor. Chem. Acc. 1998, 100, 134

  12. Labelling of the solvent DMSO as side reaction of methylations with n.c.a. [11C]CH3I.

    PubMed

    Klein, A T; Holschbach, M

    2001-09-01

    Competing labelling of solvent dimethyl sulfoxide (DMSO) can occur during the 11C-methylation of amine precursors. A kinetic analysis of the methylation reaction of DMSO with n.c.a. [11C]CH3I was performed at 120 degrees C resulting in rate constants. The rate constant for the formation of the intermediate, methylated DMSO ([11C]DMSO-M), is compared to the reaction of [11C]CH3I with two tertiary amines, namely Dexetimide and Desmethyloxotremorine-M. The specific activity of the labelled product is reduced due to partial 12C-methylation of the precursor amines by [11C]DMSO-M in cases of significant DMSO labelling as side reaction. PMID:11515652

  13. Environmental effects on noble-gas hydrides: HXeBr, HXeCCH, and HXeH in noble-gas and molecular matrices

    SciTech Connect

    Tsuge, Masashi E-mail: leonid.khriachtchev@helsinki.fi; Lignell, Antti; Räsänen, Markku; Khriachtchev, Leonid E-mail: leonid.khriachtchev@helsinki.fi

    2013-11-28

    Noble-gas hydrides HNgY (Ng is a noble-gas atom and Y is an electronegative group) are sensitive probes of local environment due to their relatively weak bonding and large dipole moments. We experimentally studied HXeBr in Ar, Kr, and N{sub 2} matrices, HXeCCH in Ne and N{sub 2} matrices, and HXeH in an N{sub 2} matrix. These are the first observations of noble-gas hydrides in an N{sub 2} matrix. An N{sub 2} matrix strongly increases the H–Xe stretching frequency of HXeBr and HXeCCH with respect to a Ne matrix, which is presumably due to a strong interaction between the HNgY dipole moment and quadrupole moments of the surrounding lattice N{sub 2} molecules. The spectral shift of HXeBr in an N{sub 2} matrix is similar to that in a CO{sub 2} matrix, which is a rather unexpected result because the quadrupole moment of CO{sub 2} is about three times as large as that of N{sub 2}. The H–Xe stretching frequencies of HXeBr and HXeCCH in noble-gas matrices show a trend of ν(Ne) < ν(Xe) < ν(Kr) < ν(Ar), which is a non-monotonous function of the dielectric constants of the noble-gas solids. The MP2(full) calculations of HXeBr and HXeCCH with the polarizable continuum model as well as the CCSD(T) calculations of the HXeBr···Ng and HXeCCH···Ng (Ng = Ne, Ar, Kr, and Xe) complexes cannot fully explain the experimental observations. It is concluded that more sophisticated computational models should be used to describe these experimental findings.

  14. Photofragment imaging study of the CH{sub 2}CCH{sub 2}OH radical intermediate of the OH+allene reaction

    SciTech Connect

    Raman, Arjun S.; Justine Bell, M.; Lau, K.-C.; Butler, Laurie J.

    2007-10-21

    These velocity map imaging experiments characterize the photolytic generation of one of the two radical intermediates formed when OH reacts via an addition mechanism with allene. The CH{sub 2}CCH{sub 2}OH radical intermediate is generated photolytically from the photodissociation of 2-chloro-2-propen-1-ol at 193 nm. Detecting the Cl atoms using [2+1] resonance-enhanced multiphoton ionization evidences an isotropic angular distribution for the Cl+CH{sub 2}CCH{sub 2}OH photofragments, a spin-orbit branching ratio for Cl({sup 2}P{sub 1/2}):Cl({sup 2}P{sub 3/2}) of 0.28, and a bimodal recoil kinetic energy distribution. Conservation of momentum and energy allows us to determine from this data the internal energy distribution of the nascent CH{sub 2}CCH{sub 2}OH radical cofragment. To assess the possible subsequent decomposition pathways of this highly vibrationally excited radical intermediate, we include electronic structure calculations at the G3//B3LYP level of theory. They predict the isomerization and dissociation transition states en route from the initial CH{sub 2}CCH{sub 2}OH radical intermediate to the three most important product channels for the OH+allene reaction expected from this radical intermediate: formaldehyde+C{sub 2}H{sub 3}, H+acrolein, and ethene+CHO. We also calculate the intermediates and transition states en route from the other radical adduct, formed by addition of the OH to the center carbon of allene, to the ketene+CH{sub 3} product channel. We compare our results to a previous theoretical study of the O+allyl reaction conducted at the CBS-QB3 level of theory, as the two reactions include several common intermediates.

  15. On the nature of the oscillations of the membrane potential (slow waves) produced by acetylcholine or carbachol in intestinal smooth muscle.

    PubMed

    Bolton, T B

    1971-07-01

    1. Intracellular recording was made with glass micro-electrodes from cells of the longitudinal muscle of the guinea-pig ileum in isotonic and in hypertonic solution.2. In isotonic solution spontaneous bursts of electrical activity occurred; these consisted of a slow potential component which carried a burst of spike action potentials. Acetylcholine increased the size (and the frequency) of the slow potential component. This had the effect of first reducing and then abolishing the spike potentials; continuous slow wave activity was thus produced. Slow waves were about 1 sec in duration and up to 50 mV in size in isotonic solution.3. In hypertonic solution the membrane potential was stable. There were no spontaneous spikes and no slow potentials. However, spikes, but not slow potentials, were elicited by depolarizing current. Carbachol (or acetylcholine) reduced the membrane potential and initiated spikes and oscillations of the membrane potential (slow waves). Slow waves were 2-5 sec in duration and 10-40 mV in size in hypertonic solution.4. The response to carbachol in hypertonic solution was unaffected by surgical denervation of the tissue, by tetrodotoxin, or by ganglion blocking agents, indicating that muscarinic stimulants produced their effects by acting directly on the smooth muscle cell.5. In hypertonic solution slow waves occurred only in the presence of a muscarinic stimulant and could not be elicited with depolarizing current (unless carbachol was present) nor by increasing the external potassium concentration.6. In hypertonic solution slow waves were abolished by hyperpolarizing the membrane and their rate of rise was proportional to the level of the membrane potential from which they arose. The membrane resistance was reduced at the peak of the slow wave. Slow waves were rapidly abolished by sodium-deficient solutions but spikes were not.7. It is suggested that slow waves represent an inward current through a slow, sodium-sensitive and voltage

  16. Acute Aerobic Swimming Exercise Induces Distinct Effects in the Contractile Reactivity of Rat Ileum to KCl and Carbachol

    PubMed Central

    Araujo, Layanne C. da Cunha; de Souza, Iara L. L.; Vasconcelos, Luiz H. C.; Brito, Aline de Freitas; Queiroga, Fernando R.; Silva, Alexandre S.; da Silva, Patrícia M.; Cavalcante, Fabiana de Andrade; da Silva, Bagnólia A.

    2016-01-01

    Aerobic exercise promotes short-term physiological changes in the intestinal smooth muscle associated to the ischemia-reperfusion process; however, few studies have demonstrated its effect on the intestinal contractile function. Thus, this work describes our observations regarding the influence of acute aerobic swimming exercise in the contractile reactivity, oxidative stress, and morphology of rat ileum. Wistar rats were divided into sedentary (SED) and acutely exercised (EX-AC) groups. Animals were acclimated by 10, 10, and 30 min of swimming exercise in intercalated days 1 week before exercise. Then they were submitted to forced swimming for 1 h with a metal of 3% of their body weight attached to their body. Animals were euthanized immediately after the exercise section and the ileum was suspended in organ baths for monitoring isotonic contractions. The analysis of lipid peroxidation was performed in order to determinate the malondialdehyde (MDA) levels as a marker of oxidative stress, and intestinal smooth muscle morphology by histological staining. Cumulative concentration-response curves to KCl were altered in the EX-AC with an increase in both its efficacy and potency (Emax = 153.2 ± 2.8%, EC50 = 1.3 ± 0.1 × 10−2 M) compared to the SED group (Emax = 100%, EC50 = 1.8 ± 0.1 × 10−2 M). Interestingly, carbachol had its efficacy and potency reduced in the EX-AC (Emax = 67.1 ± 1.4%, EC50 = 9.8 ± 1.4 × 10−7 M) compared to the SED group (Emax = 100%, EC50 = 2.0 ± 0.2 × 10−7 M). The exercise did not alter the MDA levels in the ileum (5.4 ± 0.6 μ mol/mL) in the EX-AC compared to the SED group (8.4 ± 1.7 μ mol/mL). Moreover, neither the circular nor the longitudinal smooth muscle layers thickness were modified by the exercise (66.2 ± 6.0 and 40.2 ± 2.6 μm, respectively), compared to the SED group (61.6 ± 6.4 and 34.8 ± 3.7 μm, respectively). Therefore, the ileum sensitivity to contractile agents is differentially altered by the acute aerobic

  17. Distortion of ethyne on coordination to silver acetylide, C2H2ṡṡṡAgCCH, characterised by broadband rotational spectroscopy and ab initio calculations

    NASA Astrophysics Data System (ADS)

    Stephens, Susanna L.; Zaleski, Daniel P.; Mizukami, Wataru; Tew, David P.; Walker, Nicholas R.; Legon, Anthony C.

    2014-03-01

    The rotational spectra of six isotopologues of a complex of ethyne and silver acetylide, C2H2ṡṡṡAgCCH, are measured by both chirped-pulse and Fabry-Perot cavity versions of Fourier-transform microwave spectroscopy. The complex is generated through laser ablation of a silver target in the presence of a gas sample containing 1% C2H2, 1% SF6, and 98% Ar undergoing supersonic expansion. Rotational, A0, B0, C0, and centrifugal distortion ΔJ and ΔJK constants are determined for all isotopologues of C2H2ṡṡṡAgCCH studied. The geometry is planar, C2v and T-shaped in which the C2H2 sub-unit comprises the bar of the "T" and binds to the metal atom through its π electrons. In the r0 geometry, the distance of the Ag atom from the centre of the triple bond in C2H2 is 2.2104(10) Å. The r(HC≡CH) parameter representing the bond distance separating the two carbon atoms and the angle, ∠(CCH), each defined within the C2H2 sub-unit, are determined to be 1.2200(24) Å and 186.0(5)°, respectively. This distortion of the linear geometry of C2H2 involves the hydrogen atoms moving away from the silver atom within the complex. The results thus reveal that the geometry of C2H2 changes measurably on coordination to AgCCH. A value of 59(4) N m-1 is determined for the intermolecular force constant, kσ, confirming that the complex is significantly more strongly bound than hydrogen and halogen-bonded analogues. Ab initio calculations of the re geometry at the CCSD(T)(F12*)/ACVTZ level of theory are consistent with the experimental results. The spectra of the 107Ag13C13CH and 109Ag13C13CH isotopologues of free silver acetylide are also measured for the first time allowing the geometry of the AgCCH monomer to be examined in greater detail than previously.

  18. Beta 1- and beta 2-adrenoceptor antagonist activities of ICI-215001, a putative beta 3-adrenoceptor agonist.

    PubMed Central

    Tesfamariam, B.; Allen, G. T.

    1994-01-01

    1. The present study was undertaken to characterize the beta 3-adrenoceptor agonist activity of ICI-215001 and to determine whether it exhibits additional activities on beta 1- and beta 2-adrenoceptors in isolated spontaneously beating atrium, trachea and ileum of guinea-pig. 2. In guinea-pig atrium, isoprenaline, a non-selective beta-adrenoceptor agonist, caused concentration-dependent, positive chronotropic effects that were inhibited by atenolol, a selective beta 1-antagonist. ICI-215001 also competitively antagonized the increase in heart rate caused by isoprenaline. 3. ICI-215001 exhibited low intrinsic activity at increasing the beating rate of atrium and no activity on resting or induced tone of tracheal strips. 4. In strips of guinea-pig trachea, contracted submaximally with carbachol, isoprenaline, caused concentration-dependent relaxations. Both ICI-118551, a selective beta 2-adrenoceptor antagonist, and ICI-215001 competitively inhibited the relaxations caused by isoprenaline. 5. In isolated strips of guinea-pig ileum longitudinal smooth muscle contracted with histamine, isoprenaline and ICI-215001 caused relaxations which were inhibited by alprenolol, a beta-adrenoceptor antagonist with modest affinity for beta 3-adrenoceptors, but were resistant to ICI-118551 and atenolol. 6. These results indicate that ICI-215001 exhibits beta 3-adrenoceptor agonist activity as demonstrated by relaxations mediated via atypical beta-adrenoceptors in the longitudinal smooth muscle of guinea-pig ileum. Further, the studies demonstrate that ICI-215001 can act as an antagonist at beta 1- and beta 2-adrenoceptors in situations where its intrinsic agonist activity is low. PMID:7913381

  19. Changes in the contractile responses to carbachol and in the inhibitory effects of verapamil and nitrendipine on isolated smooth muscle preparations from rats subchronically exposed to Co2+ and Ni2+.

    PubMed

    Vassilev, P P; Venkova, K; Pencheva, N; Staneva-Stoytcheva, D

    1993-01-01

    Male Wistar rats were exposed to subtoxic doses of Co2+ or Ni2+, receiving Co(NO3)2 or NiSO4 with drinking water for 30 days. No significant differences in the body weight and no visible changes in the behaviour of the controls and experimental animals were established. Cumulative concentration-effect curves for carbachol were obtained in ileum and trachea isolated from control and Co(2+)- or Ni(2+)-treated rats. The effect of the Ca2+ antagonists on the carbachol-induced contractions was studied by adding increasing concentrations of verapamil or nitrendipine to the bath solution 20 min prior to carbachol. The results showed that exposure of rats to subtoxic doses of Co(NO3)2 or NiSO4 altered the contractile responses to carbachol. The changes in the pD2 values and the shift to the left of the concentration-effect curves suggest a higher sensitivity to carbachol in preparations from the ileum of Co(2+)- or Ni(2+)-exposed rats. The tracheal strips isolated from control and heavy metal-treated rats showed a less potent sensitiveness to carbachol as compared to the ileal segments. An opposite tendency for decreased cholinergic reactivity was observed in tracheal strips from Co(2+)- and Ni(2+)-treated animals. The inhibitory effect of the Ca(2+)-antagonists on the contractility of ileal preparations from Co(2+)-treated rats increased at all concentrations of verapamil and at the highest concentration of nitrendipine, but decreased at lower concentrations of nitrendipine. The effect of verapamil on the preparations from Ni(2+)-exposed rats was unchanged or even decreased at higher verapamil concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. The action of cholinergic agonists on the squid stellate ganglion giant synapse.

    PubMed

    Stanley, E F

    1984-07-01

    Although the giant synapse in the squid stellate ganglion has served as a model in the understanding of the ionic and electrical changes that occur during the release of transmitter from nerve terminals, little is known about the pharmacology of this synapse or the identity of its neurotransmitter. In the present study, the suggestion that acetylcholine (ACh) is the excitatory transmitter at this synapse was tested by exploring the actions of cholinergic agents on the pre- and postsynaptic giant axons and on the excitatory postsynaptic potential (EPSP). A novel arterial perfusion technique that circumvents the diffusion barrier from the bathing medium to the synapse has been used to demonstrate a depolarizing action of ACh and its agonist carbachol on the post- but not the presynaptic axon. The cholinergic receptors are distinct from receptors activated by amino acids, such as glutamate, have a reversal potential of about -48 mV, are anion-permeable, and desensitize without blocking the EPSP. It is concluded that these receptors are involved in an inhibitory input onto the postsynaptic giant axon and, therefore, that ACh is most probably not the transmitter at the squid giant synapse.

  1. Inhibition of Rho-associated kinase blocks agonist-induced Ca2+ sensitization of myosin phosphorylation and force in guinea-pig ileum

    PubMed Central

    Swärd, Karl; Dreja, Karl; Susnjar, Marija; Hellstrand, Per; Hartshorne, David J; Walsh, Michael P

    2000-01-01

    Ca2+ sensitization of smooth muscle contraction involves the small GTPase RhoA, inhibition of myosin light chain phosphatase (MLCP) and enhanced myosin regulatory light chain (LC20) phosphorylation. A potential effector of RhoA is Rho-associated kinase (ROK).The role of ROK in Ca2+ sensitization was investigated in guinea-pig ileum.Contraction of permeabilized muscle strips induced by GTPγS at pCa 6.5 was inhibited by the kinase inhibitors Y-27632, HA1077 and H-7 with IC50 values that correlated with the known Ki values for inhibition of ROK. GTPγS also increased LC20 phosphorylation and this was prevented by HA1077. Contraction and LC20 phosphorylation elicited at pCa 5.75 were, however, unaffected by HA1077.Pre-treatment of intact tissue strips with HA1077 abolished the tonic component of carbachol-induced contraction and the sustained elevation of LC20 phosphorylation, but had no effect on the transient or sustained increase in [Ca2+]i induced by carbachol.LC20 phosphorylation and contraction dynamics suggest that the ROK-mediated increase in LC20 phosphorylation is due to MLCP inhibition, not myosin light chain kinase activation.In the absence of Ca2+, GTPγS stimulated 35S incorporation from [35S]ATPγS into the myosin targeting subunit of MLCP (MYPT). The enhanced thiophosphorylation was inhibited by HA1077. No thiophosphorylation of LC20 was detected.These results indicate that ROK mediates agonist-induced increases in myosin phosphorylation and force by inhibiting MLCP activity through phosphorylation of MYPT. Under Ca2+-free conditions, ROK does not appear to phosphorylate LC20in situ, in contrast to its ability to phosphorylate myosin in vitro. In particular, ROK activation is essential for the tonic phase of agonist-induced contraction. PMID:10618150

  2. Genetic interactions between the Golgi Ca2+/H+ exchanger Gdt1 and the plasma membrane calcium channel Cch1/Mid1 in the regulation of calcium homeostasis, stress response and virulence in Candida albicans.

    PubMed

    Wang, Yanan; Wang, Junjun; Cheng, Jianqing; Xu, Dayong; Jiang, Linghuo

    2015-11-01

    The Golgi-localized Saccharomyces cerevisiae ScGdt1 is a member of the cation/Ca(2+) exchanger superfamily. We show here that Candida albicans CaGdt1 is the functional homolog of ScGdt1 in calcium sensitivity, and shows genetic interactions with CaCch1 or CaMid1 in response to ER stresses. In addition, similar to ScCCH1 and ScMID1, deletion of either CaCCH1 or CaMID1 leads to a growth sensitivity of cells to cold stress, which can be suppressed by deletion of CaGDT1. Furthermore, deletion of CaCCH1 leads to a severe delay in filamentation of C. albicans cells, and this defect is abolished by deletion of CaGDT1. In contrast, CaGDT1 does not show genetic interaction with CaMID1 in filamentation. Interestingly, C. albicans cells lacking both CaMID1 and CaGDT1 exhibit an intermediate virulence between C. albicans cells lacking CaCCH1 (non-virulent) and C. albicans cells lacking CaGDT1 (partially virulent), while C. albicans cells lacking both CaCCH1 and CaGDT1 are not virulent in a mouse model of systemic candidiasis. Therefore, CaGdt1 genetically interacts with the plasma membrane calcium channel, CaCch1/CaMid1, in the response of C. albicans cells to cold and ER stresses and antifungal drug challenge as well as in filamentation and virulence.

  3. Genetic interactions between the Golgi Ca2+/H+ exchanger Gdt1 and the plasma membrane calcium channel Cch1/Mid1 in the regulation of calcium homeostasis, stress response and virulence in Candida albicans.

    PubMed

    Wang, Yanan; Wang, Junjun; Cheng, Jianqing; Xu, Dayong; Jiang, Linghuo

    2015-11-01

    The Golgi-localized Saccharomyces cerevisiae ScGdt1 is a member of the cation/Ca(2+) exchanger superfamily. We show here that Candida albicans CaGdt1 is the functional homolog of ScGdt1 in calcium sensitivity, and shows genetic interactions with CaCch1 or CaMid1 in response to ER stresses. In addition, similar to ScCCH1 and ScMID1, deletion of either CaCCH1 or CaMID1 leads to a growth sensitivity of cells to cold stress, which can be suppressed by deletion of CaGDT1. Furthermore, deletion of CaCCH1 leads to a severe delay in filamentation of C. albicans cells, and this defect is abolished by deletion of CaGDT1. In contrast, CaGDT1 does not show genetic interaction with CaMID1 in filamentation. Interestingly, C. albicans cells lacking both CaMID1 and CaGDT1 exhibit an intermediate virulence between C. albicans cells lacking CaCCH1 (non-virulent) and C. albicans cells lacking CaGDT1 (partially virulent), while C. albicans cells lacking both CaCCH1 and CaGDT1 are not virulent in a mouse model of systemic candidiasis. Therefore, CaGdt1 genetically interacts with the plasma membrane calcium channel, CaCch1/CaMid1, in the response of C. albicans cells to cold and ER stresses and antifungal drug challenge as well as in filamentation and virulence. PMID:26208803

  4. Novel diazabicycloalkane delta opioid agonists.

    PubMed

    Loriga, Giovanni; Lazzari, Paolo; Manca, Ilaria; Ruiu, Stefania; Falzoi, Matteo; Murineddu, Gabriele; Bottazzi, Mirko Emilio Heiner; Pinna, Giovanni; Pinna, Gérard Aimè

    2015-09-01

    Here we report the investigation of diazabicycloalkane cores as potential new scaffolds for the development of novel analogues of the previously reported diazatricyclodecane selective delta (δ) opioid agonists, as conformationally constrained homologues of the reference δ agonist (+)-4-[(αR)-α((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide (SNC80). In particular, we have simplified the diazatricyclodecane motif of δ opioid agonist prototype 1a with bridged bicyclic cores. 3,6-diazabicyclo[3.1.1]heptane, 3,8-diazabicyclo[3.2.1]octane, 3,9-diazabicyclo[3.3.1]nonane, 3,9-diazabicyclo[4.2.1]nonane, and 3,10-diazabicyclo[4.3.1]decane were adopted as core motifs of the novel derivatives. The compounds were synthesized and biologically assayed as racemic (3-5) or diastereoisomeric (6,7) mixtures. All the novel compounds 3-7 showed δ agonism behaviour and remarkable affinity to δ receptors. Amongst the novel derivatives, 3,8-diazabicyclo[3.2.1]octane based compound 4 evidenced improved δ affinity and selectivity relative to SNC80.

  5. Microwave and Quantum Chemical Study of Intramolecular Hydrogen Bonding in 2-Propynylhydrazine (HC≡CCH2NHNH2).

    PubMed

    Møllendal, Harald; Samdal, Svein; Guillemin, Jean-Claude

    2016-06-16

    The microwave spectrum of 2-propynylhydrazine (HC≡CCH2NHNH2) was investigated in the 23-124 GHz spectral interval. The spectra of two conformers denoted I and II were assigned. I is the lower-energy form, and relative intensity measurements yielded an internal energy difference of 3.0(4) kJ/mol between I and II. The spectra of the ground and five vibrationally excited states were assigned for I, whereas only the spectrum of the ground vibrational state was assigned for II. Both I and II are each stabilized simultaneously by two intramolecular hydrogen bonds. The first of these hydrogen bonds is formed between the hydrogen atom of the -NH- part of the hydrazino group, and the second internal hydrogen bond is formed between one of the hydrogen atoms of the -NH2 part. The π-electrons of the triple bond is thus shared by these two hydrogen atoms. The shortest contact between a hydrogen atom of the hydrazino group and the π-electrons of the ethynyl group is found in lower-energy conformer I. The conformational properties of 2-propynylhydrazine were explored by MP2/cc-pVTZ and CCSD/cc-pVQZ calculations. The CCSD method predicts that seven rotameric forms exist for this compound. Five of these rotamers are stabilized by internal hydrogen bonding. The simultaneous sharing of the π-electrons of the triple bond by two hydrogen atoms occurs only in Conformers I and II, which are predicted to be the two forms with the lowest energies, with I 2.52 kJ/mol lower in energy than II. The effective rotational constants of the ground vibrational states of I and II were predicted by a combination of MP2 and CCSD calculations, whereas centrifugal distortion constants and vibration-rotation constants were calculated by the MP2 method. The theoretical spectroscopic constants are compared with the experimental counterparts. It is concluded that more refined calculations are necessary to obtain complete agreement. PMID:27196111

  6. Phase dependency of long-term potentiation induction during the intermittent bursts of carbachol-induced β oscillation in rat hippocampal slices.

    PubMed

    Nishimura, Motoshi; Nakatsuka, Hiroki; Natsume, Kiyohisa

    2012-01-01

    The rodent hippocampus possesses theta (θ) and beta (β) rhythms, which occur intermittently as bursts. Both rhythms are related to spatial memory processing in a novel environment. θ rhythm is related to spatial memory encoding process. β rhythm is related to the match/mismatch process. In the match/mismatch process, rodent hippocampus detects a representation matching sensory inputs of the current place among the retrieved internal representations of places. Long-term synaptic potentiation (LTP) is induced in both processes. The cholinergic agent carbachol induces intermittent θ and β oscillations in in vitro slices similar to in vivo bursts. LTP is facilitated during the generation of θ oscillation, suggesting that the facilitation of LTP is dependent upon the phases of intermittent burst (burst phases) of the oscillation. However, whether this is the case for β oscillation has not yet been studied. In the present study, LTP-inducing θ-burst stimulation was administered at the different burst phases of carbachol-induced β oscillations (CIBO), and the synaptic changes were measured at CA3-CA3 pyramidal cell synapses (CA3 synapse) and at CA3-CA1 pyramidal cell synapses (CA1 synapse). At the CA3 synapse, the largest magnitude of LTP was induced at the late burst phases of CIBO. At the CA1 synapse, LTP was induced only at the late burst phases. Modulation of LTP was suppressed when CIBO was blocked by the application of atropine at both synapses. The results suggest that the bursts of hippocampal β rhythm can determine the optimal temporal period for completing with the match/mismatch process.

  7. Kappa Opioid Receptor Agonist and Brain Ischemia

    PubMed Central

    Chunhua, Chen; Chunhua, Xi; Megumi, Sugita; Renyu, Liu

    2014-01-01

    Opioid receptors, especially Kappa opioid receptor (KOR) play an important role in the pathophysiological process of cerebral ischemia reperfusion injury. Previously accepted KOR agonists activity has included anti-nociception, cardiovascular, anti-pruritic, diuretic, and antitussive effects, while compelling evidence from various ischemic animal models indicate that KOR agonist have neuroprotective effects through various mechanisms. In this review, we aimed to demonstrate the property of KOR agonist and its role in global and focal cerebral ischemia. Based on current preclinical research, the KOR agonists may be useful as a neuroprotective agent. The recent discovery of salvinorin A, highly selective non-opioid KOR agonist, offers a new tool to study the role of KOR in brain HI injury and the protective effects of KOR agonist. The unique pharmacological profile of salvinorin A along with the long history of human usage provides its high candidacy as a potential alternative medication for brain HI injury. PMID:25574482

  8. Chemical and electrochemical oxidation of [Rh(β-diketonato)(CO)(P(OCH2)3CCH3)]: an experimental and DFT study.

    PubMed

    Erasmus, Johannes J C; Conradie, Jeanet

    2013-06-28

    An experimental and computational chemistry study of the reactivity of [Rh(β-diketonato)(CO)(P(OCH2)3CCH3)] complexes towards chemical and electrochemical oxidation shows that more electron withdrawing groups on the β-diketonato ligand reduce electron density on the rhodium atom to a larger extent than electron donating groups. This leads to a slower second-order oxidative addition rate, k1, and a higher electrochemical oxidation potential, E(pa)(Rh), linearly related by ln k1 = -11(1) E(pa)(Rh) - 2.3(5). The reactivity of these complexes can be predicted by their DFT calculated HOMO energies: E(HOMO) = -0.34(8)E(pa)(Rh) - 5.04(4) = 0.032(5) ln k1- 4.96(4). k1 of [Rh(β-diketonato)(CO)(P(OCH2)3CCH3)] complexes is slower than that of related [Rh(β-diketonato)(CO)(PPh3)] and [Rh(β-diketonato)(P(OPh)3)2] complexes due to the better π-acceptor ability of the CO-phosphite-rhodium combination than that of CO-PPh3-rhodium or di-phosphite-rhodium. PMID:23632432

  9. Beta-agonists and animal welfare

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of beta-agonists in animal feed is a high profile topic within the U.S. as consumers and activist groups continue to question its safety. The only beta-agonist currently available for use in swine is ractopamine hydrochloride (RAC). This is available as Paylean™ (Elanco Animal Health – FDA a...

  10. [Adrenergic beta-agonist intoxication].

    PubMed

    Carrola, Paulo; Devesa, Nuno; Silva, José Manuel; Ramos, Fernando; Alexandrino, Mário B; Moura, José J

    2003-01-01

    The authors describe two clinical cases (father and daughter), observed in the Hospital Urgency with distal tremors, anxiety, palpitations, nausea, headaches and dizziness, two hours after ingestión of cow liver. They also had leucocytosis (with neutrophylia), hypokalemia and hyperglycaemia. After treatment with potassium i.v. and propranolol, the symptoms disappeared. The symptoms recurred at home because the patients didn't take the prescribed medication and persisted for five days, with spontaneous disappearance. The serum of both patients revealed the presence of clenbuterol (65 hg/ml - father and 58 hg/ml - daughter). The animal's liver had a concentration of 1,42 mg/kg. Clenbuterol is a ß-adrenergic agonist with low specificity, with some veterinary indications. However, this substance has been illegally used as a growth's promotor. We intend to alert doctors for this problem, particularly those that work in the Urgency.

  11. β2-agonist therapy in lung disease.

    PubMed

    Cazzola, Mario; Page, Clive P; Rogliani, Paola; Matera, M Gabriella

    2013-04-01

    β2-Agonists are effective bronchodilators due primarily to their ability to relax airway smooth muscle (ASM). They exert their effects via their binding to the active site of β2-adrenoceptors on ASM, which triggers a signaling cascade that results in a number of events, all of which contribute to relaxation of ASM. There are some differences between β2-agonists. Traditional inhaled short-acting β2-agonists albuterol, fenoterol, and terbutaline provide rapid as-needed symptom relief and short-term prophylactic protection against bronchoconstriction induced by exercise or other stimuli. The twice-daily β2-agonists formoterol and salmeterol represent important advances. Their effective bronchodilating properties and long-term improvement in lung function offer considerable clinical benefits to patients. More recently, a newer β2-agonist (indacaterol) with a longer pharmacodynamic half-life has been discovered, with the hopes of achieving once-daily dosing. In general, β2-agonists have an acceptable safety profile, although there is still controversy as to whether long-acting β2-agonists may increase the risk of asthma mortality. In any case, they can induce adverse effects, such as increased heart rate, palpitations, transient decrease in PaO2, and tremor. Desensitization of β2-adrenoceptors that occurs during the first few days of regular use of β2-agonist treatment may account for the commonly observed resolution of the majority of these adverse events after the first few doses. Nevertheless, it can also induce tolerance to bronchoprotective effects of β2-agonists and has the potential to reduce bronchodilator sensitivity to them. Some novel once-daily β2-agonists (olodaterol, vilanterol, abediterol) are under development, mainly in combination with an inhaled corticosteroid or a long-acting antimuscarinic agent. PMID:23348973

  12. The evolution of beta2-agonists.

    PubMed

    Sears, M R

    2001-08-01

    Beta-agonists have been widely used in the treatment of asthma for many years Although concerns have been expressed over their safety based largely upon epidemics of increased mortality in asthmatics associated with high doses of isoprenaline in the 1960s and fenoterol in the 1970s and 1980s, the specific beta2-agonists are vital drugs in asthma management. The short-acting beta2-agonists have an important prophylactic role in the prevention of exercise-induced bronchoconstriction, and are essential in the emergency treatment of severe asthma. However, little if any benefit seems to be derived from regular use of short-acting beta2-agonists and regular or frequent use can increase the severity of the condition. The development of beta2-agonists with long-acting properties, such as salmeterol and formoterol, has provided advantages over short-acting beta-agonists, such as prolonged bronchodilation, reduced day- and night-time symptoms and improved quality of sleep, and has reduced the requirement for short-acting beta2-agonists as relief medication. Both drugs are well tolerated and, when added to inhaled corticosteroids, produce greater mprovement in lung function than increased steroid dose alone. Because of its rapid onset of action, formoterol also has the potential to be used for as-needed bronchodilator therapy in asthma.

  13. Silencing of a Germin-Like Protein Gene (CchGLP) in Geminivirus-Resistant Pepper (Capsicum chinense Jacq.) BG-3821 Increases Susceptibility to Single and Mixed Infections by Geminiviruses PHYVV and PepGMV.

    PubMed

    Mejía-Teniente, Laura; Joaquin-Ramos, Ahuizolt de Jesús; Torres-Pacheco, Irineo; Rivera-Bustamante, Rafael F; Guevara-Olvera, Lorenzo; Rico-García, Enrique; Guevara-Gonzalez, Ramon G

    2015-11-25

    Germin-like proteins (GLPs) are encoded by a family of genes found in all plants, and in terms of function, the GLPs are implicated in the response of plants to biotic and abiotic stresses. CchGLP is a gene encoding a GLP identified in a geminivirus-resistant Capsicum chinense Jacq accession named BG-3821, and it is important in geminivirus resistance when transferred to susceptible tobacco in transgenic experiments. To characterize the role of this GLP in geminivirus resistance in the original accession from which this gene was identified, this work aimed at demonstrating the possible role of CchGLP in resistance to geminiviruses in Capsicum chinense Jacq. BG-3821. Virus-induced gene silencing studies using a geminiviral vector based in PHYVV component A, displaying that silencing of CchGLP in accession BG-3821, increased susceptibility to geminivirus single and mixed infections. These results suggested that CchGLP is an important factor for geminivirus resistance in C. chinense BG-3821 accession.

  14. Silencing of a Germin-Like Protein Gene (CchGLP) in Geminivirus-Resistant Pepper (Capsicum chinense Jacq.) BG-3821 Increases Susceptibility to Single and Mixed Infections by Geminiviruses PHYVV and PepGMV

    PubMed Central

    Mejía-Teniente, Laura; Joaquin-Ramos, Ahuizolt de Jesús; Torres-Pacheco, Irineo; Rivera-Bustamante, Rafael F.; Guevara-Olvera, Lorenzo; Rico-García, Enrique; Guevara-Gonzalez, Ramon G.

    2015-01-01

    Germin-like proteins (GLPs) are encoded by a family of genes found in all plants, and in terms of function, the GLPs are implicated in the response of plants to biotic and abiotic stresses. CchGLP is a gene encoding a GLP identified in a geminivirus-resistant Capsicum chinense Jacq accession named BG-3821, and it is important in geminivirus resistance when transferred to susceptible tobacco in transgenic experiments. To characterize the role of this GLP in geminivirus resistance in the original accession from which this gene was identified, this work aimed at demonstrating the possible role of CchGLP in resistance to geminiviruses in Capsicum chinense Jacq. BG-3821. Virus-induced gene silencing studies using a geminiviral vector based in PHYVV component A, displaying that silencing of CchGLP in accession BG-3821, increased susceptibility to geminivirus single and mixed infections. These results suggested that CchGLP is an important factor for geminivirus resistance in C. chinense BG-3821 accession. PMID:26610554

  15. Tunable Electrical Conductivity and Magnetic Property of the Two Dimensional Metal Organic Framework [Cu(TPyP)Cu2(O2CCH3)4].

    PubMed

    Sengupta, Ananya; Datta, Subhadeep; Su, Chenliang; Herng, Tun Seng; Ding, Jun; Vittal, Jagadese J; Loh, Kian Ping

    2016-06-29

    The coordination chemistry between copper acetate [Cu2(OAc)4] and 5,10,15,20-tetra-4-pyridyl-21H,23H-porphine (porphyrin, H2TPyP) is found to give rise to either a 2D metal-organic framework (MOF) [Cu(TPyP)Cu2(O2CCH3)4] or a 3D MOF [Cu(TPyP)CuCl2]·2.5TCE·7H2O], depending on the choice of solvent. The 2D MOF can be made into a film, which was doped with 7,7,8,8-tetracyanoquinodimethane (TCNQ), and the electrical conductivity of the thin film was increased by 3 orders of magnitude with respect to that of the undoped Cu-MOF. The formation of a charge-transfer complex between TCNQ and the 2D Cu-MOF also imparts stronger paramagnetic properties than for the undoped MOF.

  16. Cannabinoid receptor agonist WIN55,212-2 and fatty acid amide hydrolase inhibitor URB597 may protect against cognitive impairment in rats of chronic cerebral hypoperfusion via PI3K/AKT signaling.

    PubMed

    Su, Shao-Hua; Wang, Yue-Qing; Wu, Yi-Fang; Wang, Da-Peng; Lin, Qi; Hai, Jian

    2016-10-15

    The present study further investigated the protective effects of cannabinoid receptor agonist WIN55,212-2 (WIN) and fatty acid amide hydrolase (FAAH) inhibitor URB597 (URB) on chronic cerebral hypoperfusion (CCH)-induced cognitive impairment in rats. Spatial learning and memory were assessed with the Morris water maze and by measuring Long-term potentiation. The expression of microtubule-associated protein-2 (MAP)-2, growth-associated protein-43 (GAP)-43, synaptophysin, cannabinoid receptor 1 (CB1), brain-derived neurotrophic factor (BDNF), FAAH, N-acylphosphatidylethanolamine phospholipase D(NAPE-PLD) and monoacyl glycerol lipase (MGL) as well as phosphoinositide 3-kinase (PI3K)/AKT signaling pathway molecules and downstream targets including AKT, phosphorylated (p-)AKT, cyclic AMP response element- binding protein (CREB), p-CREB, Bcl-2-associated death protein (BAD), p-BAD, glycogen synthase kinase (GSK)-3β, p-GSK-3β, forkhead box protein (FOXO) 3A and p-FOXO3A was determined by western blotting. WIN and URB treatment improved learning and memory performance, effects that were abolished by co-administration of the PI3K/AKT inhibitor LY294002. Moreover, WIN and URB reversed the decreases in MAP-2 and synaptophysin expression resulting from CCH, and stimulated BDNF and CB1 expression as well as CREB, FOXO3A, GSK-3β, and BAD phosphorylation, confirming that WIN and URB mediate neuroprotection by preventing neuronal apoptosis and improving cognition via PI3K/AKT signaling. These findings suggest that WIN and URB are promising agents for therapeutic management of CCH. PMID:27424778

  17. Aspirin metabolites are GPR35 agonists.

    PubMed

    Deng, Huayun; Fang, Ye

    2012-07-01

    Aspirin is widely used as an anti-inflammatory, anti-platelet, anti-pyretic, and cancer-preventive agent; however, the molecular mode of action is unlikely due entirely to the inhibition of cyclooxygenases. Here, we report the agonist activity of several aspirin metabolites at GPR35, a poorly characterized orphan G protein-coupled receptor. 2,3,5-Trihydroxybenzoic acid, an aspirin catabolite, was found to be the most potent GPR35 agonist among aspirin metabolites. Salicyluric acid, the main metabolite of aspirin, was also active. These results suggest that the GPR35 agonist activity of certain aspirin metabolites may contribute to the clinical features of aspirin. PMID:22526472

  18. Monoterpenoid agonists of TRPV3

    PubMed Central

    Vogt-Eisele, A K; Weber, K; Sherkheli, M A; Vielhaber, G; Panten, J; Gisselmann, G; Hatt, H

    2007-01-01

    Background and purpose: Transient receptor potential (TRP) V3 is a thermosensitive ion channel expressed predominantly in the skin and neural tissues. It is activated by warmth and the monoterpene camphor and has been hypothesized to be involved in skin sensitization. A selection of monoterpenoid compounds was tested for TRPV3 activation to establish a structure-function relationship. The related channel TRPM8 is activated by cool temperatures and a number of chemicals, among them the monoterpene (-)-menthol. The overlap of the receptor pharmacology between the two channels was investigated. Experimental approach: Transfected HEK293 cells were superfused with the test substances. Evoked currents were measured in whole cell patch clamp measurements. Dose-response curves for the most potent agonists were obtained in Xenopus laevis oocytes. Key results: Six monoterpenes significantly more potent than camphor were identified: 6-tert-butyl-m-cresol, carvacrol, dihydrocarveol, thymol, carveol and (+)-borneol. Their EC50 is up to 16 times lower than that of camphor. All of these compounds carry a ring-located hydroxyl group and neither activates TRPM8 to a major extent. Conclusions and implications: Terpenoids have long been recognized as medically and pharmacologically active compounds, although their molecular targets have only partially been identified. TRPV3 activation may be responsible for several of the described effects of terpenoids. We show here that TRPV3 is activated by a number of monoterpenes and that a secondary hydroxyl-group is a structural requirement. PMID:17420775

  19. Agonist-sensitive calcium pool in the pancreatic acinar cell. I. Permeability properties

    SciTech Connect

    Muallem, S.; Schoeffield, M.S.; Fimmel, C.J.; Pandol, S.J.

    1988-08-01

    45Ca2+ fluxes and free cytosolic Ca2+ (( Ca2+)i) were used to describe the Ca2+ permeability and Ca2+ reloading of the agonist-sensitive pool at rest, during stimulation, and at termination of stimulation. A sequence of stimulation with carbachol, inhibition with atropine (cycling), and restimulation with cholecystokinin octapeptide (CCK-8) was used to follow Ca2+ reloading. Reloading of the pool required extracellular Ca2+ and was measured as an increased rate and extent of 45Ca2+ uptake into the acini. The 45Ca2+ incorporated into cycled acini could be completely released with CCK-8. The dose-response curves for 45Ca uptake and release were identical to those of the hormonally evoked (Ca2+)i increase. The increased 45Ca2+ uptake during reloading was not due to an expansion of any intracellular pool size but reflects the labeling of the pool to isotopic equilibrium in cycled acini. The rate constant of Ca2+ efflux from the pool of resting cells was approximately 0.67 +/- 0.01/h. With stimulation, the Ca2+ permeability of the pool membrane rapidly increased, resulting in Ca2+ release into the cytosol and an increase in (Ca2+)i. With termination of stimulation, the Ca2+ permeability of the pool membrane rapidly decreased while the pool continued to reload with extracellular Ca2+. Labeling of the pool to isotopic equilibrium allowed determination of the amount of Ca2+ released from the pool, which was 2.94 +/- 0.06 nmol/mg protein. This indicates that total Ca2+ concentration in the pool is in the millimolar range.

  20. Agonist activation of cytosolic Ca2+ in subfornical organ cells projecting to the supraoptic nucleus

    NASA Technical Reports Server (NTRS)

    Johnson, R. F.; Beltz, T. G.; Sharma, R. V.; Xu, Z.; Bhatty, R. A.; Johnson, A. K.

    2001-01-01

    The subfornical organ (SFO) is sensitive to both ANG II and ACh, and local application of these agents produces dipsogenic responses and vasopressin release. The present study examined the effects of cholinergic drugs, ANG II, and increased extracellular osmolarity on dissociated, cultured cells of the SFO that were retrogradely labeled from the supraoptic nucleus. The effects were measured as changes in cytosolic calcium in fura 2-loaded cells by using a calcium imaging system. Both ACh and carbachol increased intracellular ionic calcium concentration ([Ca2+]i). However, in contrast to the effects of muscarinic receptor agonists on SFO neurons, manipulation of the extracellular osmolality produced no effects, and application of ANG II produced only moderate effects on [Ca2+]i in a few retrogradely labeled cells. The cholinergic effects on [Ca2+]i could be blocked with the muscarinic receptor antagonist atropine and with the more selective muscarinic receptor antagonists pirenzepine and 4-diphenylacetoxy-N-methylpiperdine methiodide (4-DAMP). In addition, the calcium in the extracellular fluid was required for the cholinergic-induced increase in [Ca2+]i. These findings indicate that ACh acts to induce a functional cellular response in SFO neurons through action on a muscarinic receptor, probably of the M1 subtype and that the increase of [Ca2+]i, at least initially, requires the entry of extracellular Ca2+. Also, consistent with a functional role of M1 receptors in the SFO are the results of immunohistochemical preparations demonstrating M1 muscarinic receptor-like protein present within this forebrain circumventricular organ.

  1. [Safety of beta-agonists in asthma].

    PubMed

    Oscanoa, Teodoro J

    2014-01-01

    Beta 2 agonist bronchodilators (β2A) are very important part in the pharmacotherapy of bronchial asthma, a disease that progresses in the world in an epidemic way. The β2A are prescribed to millions of people around the world, therefore the safety aspects is of public interest. Short-Acting β2 Agonists (SABAs), such as albuterol inhaler, according to current evidence, confirming its safety when used as a quick-relief or rescue medication. The long-acting β2 agonists (LABAs) The long-acting bronchodilators β2A (Long acting β2 Agonists or LABAs) are used associated with inhaled corticosteroids as controller drugs for asthma exacerbationsaccess, for safety reasons LABAs are not recommended for use as monotherapy.

  2. Modulation of NMDA effects on agonist-stimulated phosphoinositide turnover by memantine in neonatal rat cerebral cortex.

    PubMed Central

    Mistry, R; Wilke, R; Challiss, R A

    1995-01-01

    1. The ability of memantine (1-amino-3,5-dimethyladamantane) to antagonize the modulatory effects of N-methyl-D-aspartate (NMDA) on phosphoinositide turnover stimulated by muscarinic cholinoceptor- and metabotropic glutamate receptor-agonists has been examined in neonatal rat cerebral cortex slices. 2. Memantine antagonized the inhibitory effect of NMDA (100 microM) on both total [3H]-inositol phosphate ([3H]-InsPx) and inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) mass accumulations stimulated by carbachol (1 mM) with EC50 values of 21 and 16 microM respectively. 3. Memantine concentration-dependently antagonized (IC50 24 microM) the ability of NMDA (10 microM) to potentiate [3H]-InsPx accumulation in response to a sub-maximal concentration of the metabotropic glutamate receptor agonist, 1S,3R-ACPD (10 microM). 4. The small (approx. 3 fold), concentration-dependent increase in [3H]-InsPx accumulation stimulated by NMDA was completely antagonized by the prototypic NDMA receptor-channel blocker, MK-801 (1 microM) at all concentrations of NDMA studied (1-1000 microM). In contrast, antagonism by memantine (100 microM) was observed only at low concentrations of NMDA (1-10 microM), whilst [3H]-InsPx accumulation stimulated by high concentrations of NMDA (300-1000 microM) was markedly enhanced by memantine. 5. Assessment of the incorporation of [3H]-inositol into inositol phospholipids revealed that memantine (100 microM) caused an approximate 2 fold increase in the labelling of phosphatidylinositol, phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7773540

  3. RQ-00201894: A motilin receptor agonist causing long-lasting facilitation of human gastric cholinergically-mediated contractions.

    PubMed

    Broad, John; Takahashi, Nobuyuki; Tajimi, Masaomi; Sudo, Masaki; Góralczyk, Adam; Parampalli, Umesh; Mannur, Kesava; Yamamoto, Toshinori; Sanger, Gareth J

    2016-02-01

    The aim was to characterise RQ-00201894, a novel non-macrolide motilin agonist, using human recombinant receptors and then investigate its ability to facilitate cholinergic activity in human stomach. A reporter gene assay assessed motilin receptor function. Selectivity of action was determined using a panel of different receptors, ion channels, transporters and enzymes. Cholinergically-mediated muscle contractions were evoked by electrical field stimulation (EFS) of human gastric antrum. The results showed that RQ-00201894, motilin and erythromycin acted as full motilin receptor agonists (EC50: 0.20, 0.11, 69 nM, respectively). In this function, RQ-00201894 had >90-fold selectivity of action over its ability to activate the human ghrelin receptor (EC50 19 nM) and greater selectivity over all other receptors/mechanisms tested. In human stomach RQ-00201894 0.1-30 μM concentration-dependently increased EFS-evoked contractions (up to 1209%; pEC50 6.0). At 0.1-10 μM this activity was usually prolonged. At higher concentrations (3-30 μM) RQ-00201894 also caused a short-lasting muscle contraction, temporally disconnected from the increase in EFS-evoked contractions. RQ-00201894 10 μM did not consistently affect submaximal contractions evoked by carbachol. In conclusion, RQ-00201894 potently and selectively activates the motilin receptor and causes long-lasting facilitation of cholinergic activity in human stomach, an activity thought to correlate with an ability to increase gastric emptying. PMID:26685754

  4. Dopamine receptor partial agonists and addiction.

    PubMed

    Moreira, Fabricio A; Dalley, Jeffrey W

    2015-04-01

    Many drugs abused by humans acutely facilitate, either directly or indirectly, dopamine neurotransmission in the mesolimbic pathway. As a consequence dopamine receptor agonists and antagonists have been widely investigated as putative pharmacological therapies for addiction. This general strategy, however, has had only limited success due in part to poor treatment adherence and efficacy and the significant adverse effects of dopaminergic medications. In this perspective, we discuss the potential therapeutic use of dopamine receptor partial agonists in addiction, developed initially as antipsychotic agents. Recent research indicates that the dopamine D2 receptor partial agonists, such as aripiprazole, also shows useful ancillary efficacy in several animal models of psychostimulant and opioid addiction. Notably, these findings suggest that unlike full dopamine receptor agonists and antagonists these compounds have low abuse liability and are generally well tolerated. Indeed, partial dopamine agonists attenuate the rewarding properties of opioids without interfering with their analgesic effects. Herein we discuss the utility and potential of dopamine receptor partial agonists as treatments for both stimulant and non-stimulant drug addiction.

  5. PPAR Agonists and Cardiovascular Disease in Diabetes.

    PubMed

    Calkin, Anna C; Thomas, Merlin C

    2008-01-01

    Peroxisome proliferators activated receptors (PPARs) are ligand-activated nuclear transcription factors that play important roles in lipid and glucose homeostasis. To the extent that PPAR agonists improve diabetic dyslipidaemia and insulin resistance, these agents have been considered to reduce cardiovascular risk. However, data from murine models suggests that PPAR agonists also have independent anti-atherosclerotic actions, including the suppression of vascular inflammation, oxidative stress, and activation of the renin angiotensin system. Many of these potentially anti-atherosclerotic effects are thought to be mediated by transrepression of nuclear factor-kB, STAT, and activator protein-1 dependent pathways. In recent clinical trials, PPARalpha agonists have been shown to be effective in the primary prevention of cardiovascular events, while their cardiovascular benefit in patients with established cardiovascular disease remains equivocal. However, the use of PPARgamma agonists, and more recently dual PPARalpha/gamma coagonists, has been associated with an excess in cardiovascular events, possibly reflecting unrecognised fluid retention with potent agonists of the PPARgamma receptor. Newer pan agonists, which retain their anti-atherosclerotic activity without weight gain, may provide one solution to this problem. However, the complex biologic effects of the PPARs may mean that only vascular targeted agents or pure transrepressors will realise the goal of preventing atherosclerotic vascular disease.

  6. PPAR Agonists and Cardiovascular Disease in Diabetes

    PubMed Central

    Calkin, Anna C.; Thomas, Merlin C.

    2008-01-01

    Peroxisome proliferators activated receptors (PPARs) are ligand-activated nuclear transcription factors that play important roles in lipid and glucose homeostasis. To the extent that PPAR agonists improve diabetic dyslipidaemia and insulin resistance, these agents have been considered to reduce cardiovascular risk. However, data from murine models suggests that PPAR agonists also have independent anti-atherosclerotic actions, including the suppression of vascular inflammation, oxidative stress, and activation of the renin angiotensin system. Many of these potentially anti-atherosclerotic effects are thought to be mediated by transrepression of nuclear factor-kB, STAT, and activator protein-1 dependent pathways. In recent clinical trials, PPARα agonists have been shown to be effective in the primary prevention of cardiovascular events, while their cardiovascular benefit in patients with established cardiovascular disease remains equivocal. However, the use of PPARγ agonists, and more recently dual PPARα/γ coagonists, has been associated with an excess in cardiovascular events, possibly reflecting unrecognised fluid retention with potent agonists of the PPARγ receptor. Newer pan agonists, which retain their anti-atherosclerotic activity without weight gain, may provide one solution to this problem. However, the complex biologic effects of the PPARs may mean that only vascular targeted agents or pure transrepressors will realise the goal of preventing atherosclerotic vascular disease. PMID:18288280

  7. Inositol 1,4,5-trisphosphate (IP3)-mediated Ca2+ release evoked by metabotropic agonists and backpropagating action potentials in hippocampal CA1 pyramidal neurons.

    PubMed

    Nakamura, T; Nakamura, K; Lasser-Ross, N; Barbara, J G; Sandler, V M; Ross, W N

    2000-11-15

    We examined the properties of [Ca(2+)](i) changes that were evoked by backpropagating action potentials in pyramidal neurons in hippocampal slices from the rat. In the presence of the metabotropic glutamate receptor (mGluR) agonists t-ACPD, DHPG, or CHPG, spikes caused Ca(2+) waves that initiated in the proximal apical dendrites and spread over this region and in the soma. Consistent with previously described synaptic responses (Nakamura et al., 1999a), pharmacological experiments established that the waves were attributable to Ca(2+) release from internal stores mediated by the synergistic effect of receptor-mobilized inositol 1,4, 5-trisphosphate (IP(3)) and spike-evoked Ca(2+). The amplitude of the changes reached several micromoles per liter when detected with the low-affinity indicators fura-6F, fura-2-FF, or furaptra. Repetitive brief spike trains at 30-60 sec intervals generated increases of constant amplitude. However, trains at intervals of 10-20 sec evoked smaller increases, suggesting that the stores take 20-30 sec to refill. Release evoked by mGluR agonists was blocked by MCPG, AIDA, 4-CPG, MPEP, and LY367385, a profile consistent with the primacy of group I receptors. At threshold agonist concentrations the release was evoked only in the dendrites; threshold antagonist concentrations were effective only in the soma. Carbachol and 5-HT evoked release with the same spatial distribution as t-ACPD, suggesting that the distribution of neurotransmitter receptors was not responsible for the restricted range of regenerative release. Intracellular BAPTA and EGTA were approximately equally effective in blocking release. Extracellular Cd(2+) blocked release, but no single selective Ca(2+) channel blocker prevented release. These results suggest that IP(3) receptors are not associated closely with specific Ca(2+) channels and are not close to each other.

  8. High-viscosity carboxymethylcellulose reduces carbachol-stimulated intestinal chloride secretion in weaned piglets fed a diet based on skimmed milk powder and maltodextrin.

    PubMed

    Lallès, Jean-Paul; Boudry, Gaëlle; Favier, Christine; Sève, Bernard

    2006-03-01

    High-viscosity carboxymethylcellulose (CMC) promotes gastrointestinal disorders, tissue alterations and bacterial overgrowth in pigs. The impact of CMC on intestinal absorptive and secretory physiology is not known. We hypothesised that CMC consumption alters intestinal Na-dependent glucose absorption and stimulates electrogenic chloride secretion. For testing this hypothesis, twenty-four piglets were weaned at 21 d of age and pair-fed for 13 d a starter diet based on skimmed milk powder and maltodextrin containing cellulose (control) or CMC. Body weight and faecal total aerobe and coliform counts were measured kinetically. At slaughter, digesta were weighed and characterised for viscosity and pH. Gastrointestinal tissues were weighed and sampled for physiology in Ussing chambers, morphometry and enzymology. Glucose absorption tended to be higher (P = 0.08) and carbachol-stimulated chloride secretion was lower (P = 0.01) with CMC in the small intestine, without changes in the colon. Aerobes were transiently higher at day 7 (P < 0.05) but coliform counts remained unchanged (P = 0.78) and beta-haemolitic Escherichia coli were virtually absent. Stomach and small-intestinal segments were heavier, and viscosity higher with CMC (0.001 < P < 0.05). The pH in the stomach was higher, and in the caecum and proximal colon lower with CMC (0.001 < P < 0.05). Jejunal villus area was slightly reduced with CMC (P < 0.05) without effects on enzyme activities (P > 0.10). In conclusion, CMC supplementation had pro-absorptive effects on the small intestine, possibly due to the absence of pathogenic E. coli in the present study.

  9. beta2-Agonists at the Olympic Games.

    PubMed

    Fitch, Kenneth D

    2006-01-01

    The different approaches that the International Olympic Committee (IOC) had adopted to beta2-agonists and the implications for athletes are reviewed by a former Olympic team physician who later became a member of the Medical Commission of the IOC (IOC-MC). Steadily increasing knowledge of the effects of inhaled beta2-agonists on health, is concerned with the fact that oral beta2-agonists may be anabolic, and rapid increased use of inhaled beta2-agonists by elite athletes has contributed to the changes to the IOC rules. Since 2001, the necessity for athletes to meet IOC criteria (i.e., that they have asthma and/or exercise-induced asthma [EIA]) has resulted in improved management of athletes. The prevalence of beta2-agonist use by athletes mirrors the known prevalence of asthma symptoms in each country, although athletes in endurance events have the highest prevalence. The age-of-onset of asthma/EIA in elite winter athletes may be atypical. Of the 193 athletes at the 2006 Winter Olympics who met th IOC's criteria, only 32.1% had childhood asthma and 48.7% of athletes reported onset at age 20 yr or older. These findings lead to speculation that years of intense endurance training may be a causative factor in bronchial hyperreactivity. The distinction between oral (prohibited in sports) and inhaled salbutamol is possible, but athletes must be warned that excessive use of inhaled salbutamol can lead to urinary concentrations similar to those observed after oral administration. This article provides justification that athletes should provide evidence of asthma or EIA before being permitted to use inhaled beta2-agonists. PMID:17085798

  10. A Substellar-mass Protostar and its Outflow of IRAS 15398-3359 Revealed by Subarcsecond-resolution Observations of H2CO and CCH

    NASA Astrophysics Data System (ADS)

    Oya, Yoko; Sakai, Nami; Sakai, Takeshi; Watanabe, Yoshimasa; Hirota, Tomoya; Lindberg, Johan E.; Bisschop, Suzanne E.; Jørgensen, Jes K.; van Dishoeck, Ewine F.; Yamamoto, Satoshi

    2014-11-01

    Subarcsecond (0.''5) images of H2CO and CCH line emission have been obtained in the 0.8 mm band toward the low-mass protostar IRAS 15398-3359 in the Lupus 1 cloud as one of the Cycle 0 projects of the Atacama Large Millimeter/Submillimeter Array. We have detected a compact component concentrated in the vicinity of the protostar and a well-collimated outflow cavity extending along the northeast-southwest axis. The inclination angle of the outflow is found to be about 20°, or almost edge-on, based on the kinematic structure of the outflow cavity. This is in contrast to previous suggestions of a more pole-on geometry. The centrally concentrated component is interpreted by use of a model of the infalling rotating envelope with the estimated inclination angle and the mass of the protostar is estimated to be less than 0.09 M ⊙. Higher spatial resolution data are needed to infer the presence of a rotationally supported disk for this source, hinted at by a weak high-velocity H2CO emission associated with the protostar.

  11. A substellar-mass protostar and its outflow of IRAS 15398–3359 revealed by subarcsecond-resolution observations of H{sub 2}CO and CCH

    SciTech Connect

    Oya, Yoko; Sakai, Nami; Watanabe, Yoshimasa; Yamamoto, Satoshi; Sakai, Takeshi; Hirota, Tomoya; Lindberg, Johan E.; Bisschop, Suzanne E.; Jørgensen, Jes K.; Van Dishoeck, Ewine F.

    2014-11-10

    Subarcsecond (0.''5) images of H{sub 2}CO and CCH line emission have been obtained in the 0.8 mm band toward the low-mass protostar IRAS 15398–3359 in the Lupus 1 cloud as one of the Cycle 0 projects of the Atacama Large Millimeter/Submillimeter Array. We have detected a compact component concentrated in the vicinity of the protostar and a well-collimated outflow cavity extending along the northeast-southwest axis. The inclination angle of the outflow is found to be about 20°, or almost edge-on, based on the kinematic structure of the outflow cavity. This is in contrast to previous suggestions of a more pole-on geometry. The centrally concentrated component is interpreted by use of a model of the infalling rotating envelope with the estimated inclination angle and the mass of the protostar is estimated to be less than 0.09 M {sub ☉}. Higher spatial resolution data are needed to infer the presence of a rotationally supported disk for this source, hinted at by a weak high-velocity H{sub 2}CO emission associated with the protostar.

  12. Theoretical prediction of new noble-gas molecules FNgBNR (Ng = Ar, Kr, and Xe; R = H, CH3, CCH, CHCH2, F, and OH).

    PubMed

    Chen, Jien-Lian; Yang, Chang-Yu; Lin, Hsiao-Jing; Hu, Wei-Ping

    2013-06-28

    We have computationally predicted a new class of stable noble-gas molecules FNgBNR (Ng = Ar, Kr, Xe; R = H, CH3, CCH, CHCH2, F, and OH). The FNgBNR were found to have compact structures with F-Ng bond lengths of 1.9-2.2 Å and Ng-B bond lengths of ~1.8 Å. The endoergic three-body dissociation energies of FNgBNH to F + Ng + BNH were calculated to be 12.8, 31.7, and 63.9 kcal mol(-1), for Ng = Ar, Kr, and Xe, respectively at the CCSD(T)/CBS level. The energy barriers of the exoergic two-body dissociation to Ng + FBNH were calculated to be 16.1, 24.0, and 33.2 kcal mol(-1) for Ng = Ar, Kr, and Xe, respectively. Our results showed that the dissociation energetics is relatively insensitive to the identities of the terminal R groups. The current study suggested that a wide variety of noble-gas containing molecules with different types of R groups can be thermally stable at low temperature, and the number of potentially stable noble-gas containing molecules would thus increase very significantly. It is expected some of the FNgBNR molecules could be identified in future experiments under cryogenic conditions in noble-gas matrices or in the gas phase.

  13. Identification of Selective ERRγ Inverse Agonists.

    PubMed

    Kim, Jina; Im, Chun Young; Yoo, Eun Kyung; Ma, Min Jung; Kim, Sang-Bum; Hong, Eunmi; Chin, Jungwook; Hwang, Hayoung; Lee, Sungwoo; Kim, Nam Doo; Jeon, Jae-Han; Lee, In-Kyu; Jeon, Yong Hyun; Choi, Hueng-Sik; Kim, Seong Heon; Cho, Sung Jin

    2016-01-12

    GSK5182 (4) is currently one of the lead compounds for the development of estrogen-related receptor gamma (ERRγ) inverse agonists. Here, we report the design, synthesis, pharmacological and in vitro absorption, distribution, metabolism, excretion, toxicity (ADMET) properties of a series of compounds related to 4. Starting from 4, a series of analogs were structurally modified and their ERRγ inverse agonist activity was measured. A key pharmacophore feature of this novel class of ligands is the introduction of a heterocyclic group for A-ring substitution in the core scaffold. Among the tested compounds, several of them are potent ERRγ inverse agonists as determined by binding and functional assays. The most promising compound, 15g, had excellent binding selectivity over related subtypes (IC50 = 0.44, >10, >10, and 10 μM at the ERRγ, ERRα, ERRβ, and ERα subtypes, respectively). Compound 15g also resulted in 95% transcriptional repression at a concentration of 10 μM, while still maintaining an acceptable in vitro ADMET profile. This novel class of ERRγ inverse agonists shows promise in the development of drugs targeting ERRγ-related diseases.

  14. Multiple tyrosine metabolites are GPR35 agonists

    PubMed Central

    Deng, Huayun; Hu, Haibei; Fang, Ye

    2012-01-01

    Both kynurenic acid and 2-acyl lysophosphatidic acid have been postulated to be the endogenous agonists of GPR35. However, controversy remains whether alternative endogenous agonists exist. The molecular targets accounted for many nongenomic actions of thyroid hormones are mostly unknown. Here we report the agonist activity of multiple tyrosine metabolites at the GPR35. Tyrosine metabolism intermediates that contain carboxylic acid and/or catechol functional groups were first selected. Whole cell dynamic mass redistribution (DMR) assays enabled by label-free optical biosensor were then used to characterize their agonist activity in native HT-29. Molecular assays including β-arrestin translocation, ERK phosphorylation and receptor internalization confirmed that GPR35 functions as a receptor for 5,6-dihydroxyindole-2-carboxylic acid, 3,3′,5′-triiodothyronine, 3,3′,5-triiodothyronine, gentisate, rosmarinate, and 3-nitrotyrosine. These results suggest that multiple tyrosine metabolites are alternative endogenous ligands of GPR35, and GPR35 may represent a druggable target for treating certain diseases associated with abnormality of tyrosine metabolism. PMID:22523636

  15. Altered parasympathetic nervous system regulation of the sinoatrial node in Akita diabetic mice.

    PubMed

    Krishnaswamy, Pooja S; Egom, Emmanuel E; Moghtadaei, Motahareh; Jansen, Hailey J; Azer, John; Bogachev, Oleg; Mackasey, Martin; Robbins, Courtney; Rose, Robert A

    2015-05-01

    Cardiovascular autonomic neuropathy (CAN) is a serious complication of diabetes mellitus that impairs autonomic regulation of heart rate (HR). This has been attributed to damage to the nerves that modulate spontaneous pacemaker activity in the sinoatrial node (SAN). Our objective was to test the hypothesis that impaired parasympathetic regulation of HR in diabetes is due to reduced responsiveness of the SAN to parasympathetic agonists. We used the Akita mouse model of type 1 diabetes to study the effects of the parasympathetic agonist carbachol (CCh) on SAN function using intracardiac programmed stimulation, high resolution optical mapping and patch-clamping of SAN myocytes. CCh decreased HR by 30% and increased corrected SAN recovery time (cSNRT) by 123% in wildtype mice. In contrast, CCh only decreased HR by 12%, and only increased cSNRT by 37% in Akita mice. These alterations were due to smaller effects of CCh on SAN electrical conduction and spontaneous action potential firing in isolated SAN myocytes. Voltage clamp experiments demonstrate that the acetylcholine-activated K(+) current (IKACh) is reduced in Akita SAN myocytes due to enhanced desensitization and faster deactivation kinetics. These IKACh alterations were normalized by treating Akita SAN myocytes with PI(3,4,5)P3 or an inhibitor of regulator of G-protein signaling 4 (RGS4). There was no difference in the effects of CCh on the hyperpolarization-activated current (If) between wildtype and Akita mice. Our study demonstrates that Akita diabetic mice demonstrate impaired parasympathetic regulation of HR and SAN function due to reduced responses of the SAN to parasympathetic agonists. Our experiments demonstrate a key role for insulin-dependent phosphoinositide 3-kinase (PI3K) signaling in the parasympathetic dysfunction seen in the SAN in diabetes. PMID:25754673

  16. FXR agonist activity of conformationally constrained analogs of GW 4064

    SciTech Connect

    Akwabi-Ameyaw, Adwoa; Bass, Jonathan Y.; Caldwell, Richard D.; Caravella, Justin A.; Chen, Lihong; Creech, Katrina L.; Deaton, David N.; Madauss, Kevin P.; Marr, Harry B.; McFadyen, Robert B.; Miller, Aaron B.; Navas, III, Frank; Parks, Derek J.; Spearing, Paul K.; Todd, Dan; Williams, Shawn P.; Wisely, G. Bruce

    2010-09-27

    Two series of conformationally constrained analogs of the FXR agonist GW 4064 1 were prepared. Replacement of the metabolically labile stilbene with either benzothiophene or naphthalene rings led to the identification of potent full agonists 2a and 2g.

  17. FXR agonist activity of conformationally constrained analogs of GW 4064.

    PubMed

    Akwabi-Ameyaw, Adwoa; Bass, Jonathan Y; Caldwell, Richard D; Caravella, Justin A; Chen, Lihong; Creech, Katrina L; Deaton, David N; Madauss, Kevin P; Marr, Harry B; McFadyen, Robert B; Miller, Aaron B; Navas, Frank; Parks, Derek J; Spearing, Paul K; Todd, Dan; Williams, Shawn P; Bruce Wisely, G

    2009-08-15

    Two series of conformationally constrained analogs of the FXR agonist GW 4064 1 were prepared. Replacement of the metabolically labile stilbene with either benzothiophene or naphthalene rings led to the identification of potent full agonists 2a and 2g.

  18. Distortion of ethyne on coordination to silver acetylide, C{sub 2}H{sub 2}⋅⋅⋅AgCCH, characterised by broadband rotational spectroscopy and ab initio calculations

    SciTech Connect

    Stephens, Susanna L.; Zaleski, Daniel P.; Walker, Nicholas R. E-mail: a.c.legon@bristol.ac.uk; Mizukami, Wataru; Tew, David P.; Legon, Anthony C. E-mail: a.c.legon@bristol.ac.uk

    2014-03-28

    The rotational spectra of six isotopologues of a complex of ethyne and silver acetylide, C{sub 2}H{sub 2}⋅⋅⋅AgCCH, are measured by both chirped-pulse and Fabry-Perot cavity versions of Fourier-transform microwave spectroscopy. The complex is generated through laser ablation of a silver target in the presence of a gas sample containing 1% C{sub 2}H{sub 2}, 1% SF{sub 6}, and 98% Ar undergoing supersonic expansion. Rotational, A{sub 0}, B{sub 0}, C{sub 0}, and centrifugal distortion Δ{sub J} and Δ{sub JK} constants are determined for all isotopologues of C{sub 2}H{sub 2}⋅⋅⋅AgCCH studied. The geometry is planar, C{sub 2v} and T-shaped in which the C{sub 2}H{sub 2} sub-unit comprises the bar of the “T” and binds to the metal atom through its π electrons. In the r{sub 0} geometry, the distance of the Ag atom from the centre of the triple bond in C{sub 2}H{sub 2} is 2.2104(10) Å. The r(HC≡CH) parameter representing the bond distance separating the two carbon atoms and the angle, ∠(CCH), each defined within the C{sub 2}H{sub 2} sub-unit, are determined to be 1.2200(24) Å and 186.0(5)°, respectively. This distortion of the linear geometry of C{sub 2}H{sub 2} involves the hydrogen atoms moving away from the silver atom within the complex. The results thus reveal that the geometry of C{sub 2}H{sub 2} changes measurably on coordination to AgCCH. A value of 59(4) N m{sup −1} is determined for the intermolecular force constant, k{sub σ}, confirming that the complex is significantly more strongly bound than hydrogen and halogen-bonded analogues. Ab initio calculations of the r{sub e} geometry at the CCSD(T)(F12{sup *})/ACVTZ level of theory are consistent with the experimental results. The spectra of the {sup 107}Ag{sup 13}C{sup 13}CH and {sup 109}Ag{sup 13}C{sup 13}CH isotopologues of free silver acetylide are also measured for the first time allowing the geometry of the AgCCH monomer to be examined in greater detail than previously.

  19. Recent advances in the discovery of alpha1-adrenoceptor agonists.

    PubMed

    Bishop, Michael J

    2007-01-01

    The alpha(1) adrenoceptors are three of nine well-characterized receptors that are activated by epinephrine and norepinephrine. Agonists acting at the alpha(1) adrenoceptors produce numerous physiological effects, and are used therapeutically for several indications. Many known alpha(1) adrenoceptor agonists are alpha(1A) selective, but the discovery of highly selective alpha(1B) and alpha(1D) adrenoceptor agonists has proven to be an extremely difficult goal to achieve. This review will focus on recent advances in the discovery, development and clinical utility of subtype-specific alpha(1) agonists as well as contributions to our understanding of agonist-receptor interactions.

  20. Increased agonist affinity at the mu-opioid receptor induced by prolonged agonist exposure

    PubMed Central

    Birdsong, William T.; Arttamangkul, Seksiri; Clark, Mary J.; Cheng, Kejun; Rice, Kenner C.; Traynor, John R.; Williams, John T.

    2013-01-01

    Prolonged exposure to high-efficacy agonists results in desensitization of the mu opioid receptor (MOR). Desensitized receptors are thought to be unable to couple to G-proteins, preventing downstream signaling, however the changes to the receptor itself are not well characterized. In the current study, confocal imaging was used to determine whether desensitizing conditions cause a change in agonist-receptor interactions. Using rapid solution exchange, the binding kinetics of fluorescently labeled opioid agonist, dermorphin Alexa594 (derm A594), to MORs was measured in live cells. The affinity of derm A594 binding increased following prolonged treatment of cells with multiple agonists that are known to cause receptor desensitization. In contrast, binding of a fluorescent antagonist, naltrexamine Alexa 594, was unaffected by similar agonist pre-treatment. The increased affinity of derm A594 for the receptor was long-lived and partially reversed after a 45 min wash. Treatment of the cells with pertussis toxin did not alter the increase in affinity of the derm A594 for MOR. Likewise the affinity of derm A594 for MORs expressed in mouse embryonic fibroblasts derived from arrestin 1 and 2 knockout animals increased following treatment of the cells with the desensitization protocol. Thus, opioid receptors were “imprinted” with a memory of prior agonist exposure that was independent of G-protein activation or arrestin binding that altered subsequent agonist-receptor interactions. The increased affinity suggests that acute desensitization results in a long lasting but reversible conformational change in the receptor. PMID:23447620

  1. Agonistic and reproductive interactions in Betta splendens.

    PubMed

    Bronstein, P M

    1984-12-01

    Reproductive and agonistic behaviors in Siamese fighting fish were investigated in eight experiments, and some consequences and determinants of these sequences were isolated. First, fights and the formation of dominance-subordinancy relations were studied. Second, it was determined that large body size as well as males' prior residency in a tank produced an agonistic advantage; the magnitude of this advantage was positively related to the duration of residency. Third, the prior-residency effect in Bettas was determined by males' familiarity with visual and/or tactile cues in their home tanks. Fourth, dominant males had greater access to living space and were more likely to display at a mirror, build nests, and approach females than were subordinates. Finally, it was discovered that chemical cues associated with presumedly inert plastic tank dividers influence Bettas' social behavior.

  2. Signal Use by Octopuses in Agonistic Interactions.

    PubMed

    Scheel, David; Godfrey-Smith, Peter; Lawrence, Matthew

    2016-02-01

    Cephalopods show behavioral parallels to birds and mammals despite considerable evolutionary distance [1, 2]. Many cephalopods produce complex body patterns and visual signals, documented especially in cuttlefish and squid, where they are used both in camouflage and a range of interspecific interactions [1, 3-5]. Octopuses, in contrast, are usually seen as solitary and asocial [6, 7]; their body patterns and color changes have primarily been interpreted as camouflage and anti-predator tactics [8-12], though the familiar view of the solitary octopus faces a growing list of exceptions. Here, we show by field observation that in a shallow-water octopus, Octopus tetricus, a range of visible displays are produced during agonistic interactions, and these displays correlate with the outcome of those interactions. Interactions in which dark body color by an approaching octopus was matched by similar color in the reacting octopus were more likely to escalate to grappling. Darkness in an approaching octopus met by paler color in the reacting octopus accompanied retreat of the paler octopus. Octopuses also displayed on high ground and stood with spread web and elevated mantle, often producing these behaviors in combinations. This study is the first to document the systematic use of signals during agonistic interactions among octopuses. We show prima facie conformity of our results to an influential model of agonistic signaling [13]. These results suggest that interactions have a greater influence on octopus evolution than has been recognized and show the importance of convergent evolution in behavioral traits. PMID:26832440

  3. Signal Use by Octopuses in Agonistic Interactions.

    PubMed

    Scheel, David; Godfrey-Smith, Peter; Lawrence, Matthew

    2016-02-01

    Cephalopods show behavioral parallels to birds and mammals despite considerable evolutionary distance [1, 2]. Many cephalopods produce complex body patterns and visual signals, documented especially in cuttlefish and squid, where they are used both in camouflage and a range of interspecific interactions [1, 3-5]. Octopuses, in contrast, are usually seen as solitary and asocial [6, 7]; their body patterns and color changes have primarily been interpreted as camouflage and anti-predator tactics [8-12], though the familiar view of the solitary octopus faces a growing list of exceptions. Here, we show by field observation that in a shallow-water octopus, Octopus tetricus, a range of visible displays are produced during agonistic interactions, and these displays correlate with the outcome of those interactions. Interactions in which dark body color by an approaching octopus was matched by similar color in the reacting octopus were more likely to escalate to grappling. Darkness in an approaching octopus met by paler color in the reacting octopus accompanied retreat of the paler octopus. Octopuses also displayed on high ground and stood with spread web and elevated mantle, often producing these behaviors in combinations. This study is the first to document the systematic use of signals during agonistic interactions among octopuses. We show prima facie conformity of our results to an influential model of agonistic signaling [13]. These results suggest that interactions have a greater influence on octopus evolution than has been recognized and show the importance of convergent evolution in behavioral traits.

  4. A crossed molecular beam and ab-initio investigation of the reaction of boron monoxide (BO; X2Σ+) with methylacetylene (CH3CCH; X1A1): competing atomic hydrogen and methyl loss pathways.

    PubMed

    Maity, Surajit; Parker, Dorian S N; Dangi, Beni B; Kaiser, Ralf I; Fau, Stefan; Perera, Ajith; Bartlett, Rodney J

    2013-11-21

    The gas-phase reaction of boron monoxide ((11)BO; X(2)Σ(+)) with methylacetylene (CH3CCH; X(1)A1) was investigated experimentally using crossed molecular beam technique at a collision energy of 22.7 kJ mol(-1) and theoretically using state of the art electronic structure calculation, for the first time. The scattering dynamics were found to be indirect (complex forming reaction) and the reaction proceeded through the barrier-less formation of a van-der-Waals complex ((11)BOC3H4) followed by isomerization via the addition of (11)BO(X(2)Σ(+)) to the C1 and/or C2 carbon atom of methylacetylene through submerged barriers. The resulting (11)BOC3H4 doublet radical intermediates underwent unimolecular decomposition involving three competing reaction mechanisms via two distinct atomic hydrogen losses and a methyl group elimination. Utilizing partially deuterated methylacetylene reactants (CD3CCH; CH3CCD), we revealed that the initial addition of (11)BO(X(2)Σ(+)) to the C1 carbon atom of methylacetylene was followed by hydrogen loss from the acetylenic carbon atom (C1) and from the methyl group (C3) leading to 1-propynyl boron monoxide (CH3CC(11)BO) and propadienyl boron monoxide (CH2CCH(11)BO), respectively. Addition of (11)BO(X(2)Σ(+)) to the C1 of methylacetylene followed by the migration of the boronyl group to the C2 carbon atom and/or an initial addition of (11)BO(X(2)Σ(+)) to the sterically less accessible C2 carbon atom of methylacetylene was followed by loss of a methyl group leading to the ethynyl boron monoxide product (HCC(11)BO) in an overall exoergic reaction (78 ± 23 kJ mol(-1)). The branching ratios of these channels forming CH2CCH(11)BO, CH3CC(11)BO, and HCC(11)BO were derived to be 4 ± 3%, 40 ± 5%, and 56 ± 15%, respectively; these data are in excellent agreement with the calculated branching ratios using statistical RRKM theory yielding 1%, 38%, and 61%, respectively. PMID:23651442

  5. Synthesis and structure of bis[(2 E)-3-(2-furyl)prop-2-enoato]triphenylantimony Ph 3Sb[O2CCH=CH(C4H3O)]2

    NASA Astrophysics Data System (ADS)

    Kalistratova, O. S.; Andreev, P. V.; Gushchin, A. V.; Somov, N. V.; Chuprunov, E. V.

    2016-05-01

    Bis[(2 E)-3-(2-furyl)prop-2-enoato]triphenylantimony Ph 3Sb[O2CCH=CH(C4H3O)]2 is obtained for the first time by the reaction of triphenylantimony, hydrogen peroxide, and 2-furylpropene acid. The X-ray diffraction data show that the central atom of antimony is coordinated in the shape of a distorted trigonal bipyramid. The base of the bipyramid is formed by carbon atoms of phenyl ligands, and the apical vertices are occupied by acid residues. The IR and NMR spectra agree with the composition and structure of the compound.

  6. A crossed molecular beam and ab-initio investigation of the reaction of boron monoxide (BO; X2Σ+) with methylacetylene (CH3CCH; X1A1): competing atomic hydrogen and methyl loss pathways.

    PubMed

    Maity, Surajit; Parker, Dorian S N; Dangi, Beni B; Kaiser, Ralf I; Fau, Stefan; Perera, Ajith; Bartlett, Rodney J

    2013-11-21

    The gas-phase reaction of boron monoxide ((11)BO; X(2)Σ(+)) with methylacetylene (CH3CCH; X(1)A1) was investigated experimentally using crossed molecular beam technique at a collision energy of 22.7 kJ mol(-1) and theoretically using state of the art electronic structure calculation, for the first time. The scattering dynamics were found to be indirect (complex forming reaction) and the reaction proceeded through the barrier-less formation of a van-der-Waals complex ((11)BOC3H4) followed by isomerization via the addition of (11)BO(X(2)Σ(+)) to the C1 and/or C2 carbon atom of methylacetylene through submerged barriers. The resulting (11)BOC3H4 doublet radical intermediates underwent unimolecular decomposition involving three competing reaction mechanisms via two distinct atomic hydrogen losses and a methyl group elimination. Utilizing partially deuterated methylacetylene reactants (CD3CCH; CH3CCD), we revealed that the initial addition of (11)BO(X(2)Σ(+)) to the C1 carbon atom of methylacetylene was followed by hydrogen loss from the acetylenic carbon atom (C1) and from the methyl group (C3) leading to 1-propynyl boron monoxide (CH3CC(11)BO) and propadienyl boron monoxide (CH2CCH(11)BO), respectively. Addition of (11)BO(X(2)Σ(+)) to the C1 of methylacetylene followed by the migration of the boronyl group to the C2 carbon atom and/or an initial addition of (11)BO(X(2)Σ(+)) to the sterically less accessible C2 carbon atom of methylacetylene was followed by loss of a methyl group leading to the ethynyl boron monoxide product (HCC(11)BO) in an overall exoergic reaction (78 ± 23 kJ mol(-1)). The branching ratios of these channels forming CH2CCH(11)BO, CH3CC(11)BO, and HCC(11)BO were derived to be 4 ± 3%, 40 ± 5%, and 56 ± 15%, respectively; these data are in excellent agreement with the calculated branching ratios using statistical RRKM theory yielding 1%, 38%, and 61%, respectively.

  7. Hydrothermal plumes in the Gulf of Aden, as characterized by light transmission, Mn, Fe, CH4 and δ13C-CH4 anomalies

    NASA Astrophysics Data System (ADS)

    Gamo, Toshitaka; Okamura, Kei; Hatanaka, Hiroshi; Hasumoto, Hiroshi; Komatsu, Daisuke; Chinen, Masakazu; Mori, Mutsumi; Tanaka, Junya; Hirota, Akinari; Tsunogai, Urumu; Tamaki, Kensaku

    2015-11-01

    We conducted water column surveys to search for hydrothermal plumes over the spreading axes in the Gulf of Aden between 45°35‧E and 52°42‧E. We measured light transmission and chemical tracers Mn, Fe, CH4 and δ13C of CH4 in seawater taken using a CTD-Carrousel multi-sampling system at 12 locations including a control station in the Arabian Sea. We recognized three types of hydrothermal plumes at depths of ~650 to ~900 m (shallow plumes), ~1000 to ~1200 m (intermediate plumes), and >1500 m (deep plumes). The shallow plumes were apparently originated from newly discovered twin seamounts (12°03-06‧N and 45°35-41‧E) at the westernmost survey area, where two-dimensional distributions of light transmission and Mn were mapped by tow-yo observations of the CTD-sampling system with an in situ auto-analyzer GAMOS. The maximum concentrations of Mn, Fe, and CH4 of 46 nM, 251 nM, and 15 nM, respectively, were observed for collected seawater within the shallow plumes. The intermediate plumes were characterized by anomalies of light transmission, Mn, Fe, and δ13C of CH4, but by little CH4 anomalies, suggesting that CH4 had been consumed down to the background level during the aging of the plumes. Anomalies of δ3He already reported by the World Ocean Circulation Experiment (WOCE) program exhibited a hydrothermal plume-like peak at ~2000 m depth in the Gulf of Aden, which seems to coincide with the deep plumes observed in this study. The endmember δ13C-CH4 values for the shallow and the deep plumes were estimated to be in a range between -10‰ and -15‰, demonstrating that the sources of CH4 are not biogenic but magmatic as similarly observed at sediment-starved mid-oceanic ridges.

  8. Atmospheric chemistry of (CF3)2C=CH2: OH radicals, Cl atoms and O3 rate coefficients, oxidation end-products and IR spectra.

    PubMed

    Papadimitriou, Vassileios C; Spitieri, Christina S; Papagiannakopoulos, Panos; Cazaunau, Mathieu; Lendar, Maria; Daële, Véronique; Mellouki, Abdelwahid

    2015-10-14

    The rate coefficients for the gas phase reactions of OH radicals, k1, Cl atoms, k2, and O3, k3, with 3,3,3-trifluoro-2(trifluoromethyl)-1-propene ((CF3)2C=CH2, hexafluoroisobutylene, HFIB) were determined at room temperature and atmospheric pressure employing the relative rate method and using two atmospheric simulation chambers and a static photochemical reactor. OH and Cl rate coefficients obtained by both techniques were indistinguishable, within experimental precision, and the average values were k1 = (7.82 ± 0.55) × 10(-13) cm(3) molecule(-1) s(-1) and k2 = (3.45 ± 0.24) × 10(-11) cm(3) molecule(-1) s(-1), respectively. The quoted uncertainties are at 95% level of confidence and include the estimated systematic uncertainties. An upper limit for the O3 rate coefficient was determined to be k3 < 9.0 × 10(-22) cm(3) molecule(-1) s(-1). In global warming potential (GWP) calculations, radiative efficiency (RE) was determined from the measured IR absorption cross-sections and treating HFIB both as long (LLC) and short (SLC) lived compounds, including estimated lifetime dependent factors in the SLC case. The HFIB lifetime was estimated from kinetic measurements considering merely the OH reaction, τOH = 14.8 days and including both OH and Cl chemistry, τeff = 10.3 days. Therefore, GWP(HFIB,OH) and GWP(HFIB,eff) were estimated to be 4.1 (LLC) and 0.6 (SLC), as well as 2.8 (LLC) and 0.3 (SLC) for a hundred year time horizon. Moreover, the estimated photochemical ozone creation potential (ε(POCP)) of HFIB was calculated to be 4.60. Finally, HCHO and (CF3)2C(O) were identified as final oxidation products in both OH- and Cl-initiated oxidation, while HC(O)Cl was additionally observed in the Cl-initiated oxidation. PMID:26372403

  9. Syntheses and reactions of polymer-bound molybdenum complexes and hydrogenolyses of an alkynyl cobalt carbonyl cluster. [Co/sub 3/(CO)/sub 9/CCH/sub 2/CCH/sub 2/C(CH/sub 3/)/sub 3/; cyclopentadienyl-(tricarbonyl) hydridomolybdenum

    SciTech Connect

    Frommer, J.E.

    1980-08-01

    Co/sub 3/(CO)/sub 9/CCH/sub 2/C(CH/sub 3/)/sub 3/ reacted with hydrogen in aromatic solvents to yield 3,3-dimethylbutene, 2,2-dimethylbutane, and 4,4-dimethylpentanal. First order decomposition of starting material and a hydrogen pressure dependence for the rate of appearance of total products were indicated. The hydrogenation was inhibited in the presence of carbon monoxide (CO:H/sub 2/, 3.7:3.7 atm, 60/sup 0/C), but at 85/sup 0/ under the same CO/H/sub 2/ atmosphere, aldehyde production became the predominant reaction pathway at the expense of earlier-formed olefin. Incorporation of independently added olefins in the hydrogenation suggested the intermediacy of olefin aldehyde ad alkane production. A polystyrene-attached n/sup 5/-cyclopentadienyl(tricarbonyl)-hydridomolybdenum complex was prepared and its reactions with several THF-soluble bases were investigated. Enolates of ..beta..-dicarbonyl compounds quantitatively deprotonated this complex, giving polymer-bound salts of the corresponding anion. Little change in pKa in THF was induced by binding the molybdenum hydride to the polymer. Even though the polymer-supported partners rendered the reactions heterogeneous, the systems adhered reasonably well to conventional equilibrium behavior. A polymer-bound carboxylic acid and its conjugate base also displayed essentially conventional equilibrium dynamics.

  10. Agonist-Directed Desensitization of the β2-Adrenergic Receptor

    PubMed Central

    Goral, Vasiliy; Jin, Yan; Sun, Haiyan; Ferrie, Ann M.; Wu, Qi; Fang, Ye

    2011-01-01

    The β2-adrenergic receptor (β2AR) agonists with reduced tachyphylaxis may offer new therapeutic agents with improved tolerance profile. However, receptor desensitization assays are often inferred at the single signaling molecule level, thus ligand-directed desensitization is poorly understood. Here we report a label-free biosensor whole cell assay with microfluidics to determine ligand-directed desensitization of the β2AR. Together with mechanistic deconvolution using small molecule inhibitors, the receptor desensitization and resensitization patterns under the short-term agonist exposure manifested the long-acting agonism of salmeterol, and differentiated the mechanisms of agonist-directed desensitization between a full agonist epinephrine and a partial agonist pindolol. This study reveals the cellular mechanisms of agonist-selective β2AR desensitization at the whole cell level. PMID:21541288

  11. Sports doping: emerging designer and therapeutic β2-agonists.

    PubMed

    Fragkaki, A G; Georgakopoulos, C; Sterk, S; Nielen, M W F

    2013-10-21

    Beta2-adrenergic agonists, or β2-agonists, are considered essential bronchodilator drugs in the treatment of bronchial asthma, both as symptom-relievers and, in combination with inhaled corticosteroids, as disease-controllers. The use of β2-agonists is prohibited in sports by the World Anti-Doping Agency (WADA) due to claimed anabolic effects, and also, is prohibited as growth promoters in cattle fattening in the European Union. This paper reviews the last seven-year (2006-2012) literature concerning the development of novel β2-agonists molecules either by modifying the molecule of known β2-agonists or by introducing moieties producing indole-, adamantyl- or phenyl urea derivatives. New emerging β2-agonists molecules for future therapeutic use are also presented, intending to emphasize their potential use for doping purposes or as growth promoters in the near future.

  12. Modulation of Innate Immune Responses via Covalently Linked TLR Agonists

    PubMed Central

    2015-01-01

    We present the synthesis of novel adjuvants for vaccine development using multivalent scaffolds and bioconjugation chemistry to spatially manipulate Toll-like receptor (TLR) agonists. TLRs are primary receptors for activation of the innate immune system during vaccination. Vaccines that contain a combination of small and macromolecule TLR agonists elicit more directed immune responses and prolong responses against foreign pathogens. In addition, immune activation is enhanced upon stimulation of two distinct TLRs. Here, we synthesized combinations of TLR agonists as spatially defined tri- and di-agonists to understand how specific TLR agonist combinations contribute to the overall immune response. We covalently conjugated three TLR agonists (TLR4, 7, and 9) to a small molecule core to probe the spatial arrangement of the agonists. Treating immune cells with the linked agonists increased activation of the transcription factor NF-κB and enhanced and directed immune related cytokine production and gene expression beyond cells treated with an unconjugated mixture of the same three agonists. The use of TLR signaling inhibitors and knockout studies confirmed that the tri-agonist molecule activated multiple signaling pathways leading to the observed higher activity. To validate that the TLR4, 7, and 9 agonist combination would activate the immune response to a greater extent, we performed in vivo studies using a vaccinia vaccination model. Mice vaccinated with the linked TLR agonists showed an increase in antibody depth and breadth compared to mice vaccinated with the unconjugated mixture. These studies demonstrate how activation of multiple TLRs through chemically and spatially defined organization assists in guiding immune responses, providing the potential to use chemical tools to design and develop more effective vaccines. PMID:26640818

  13. Small Molecule Bax Agonists for Cancer Therapy

    PubMed Central

    Xin, Meiguo; Li, Rui; Xie, Maohua; Park, Dongkyoo; Owonikoko, Taofeek K.; Sica, Gabriel L.; Corsino, Patrick E.; Zhou, Jia; Ding, Chunyong; White, Mark A.; Magis, Andrew T.; Ramalingam, Suresh S.; Curran, Walter J.; Khuri, Fadlo R.; Deng, Xingming

    2014-01-01

    Bax, a central death regulator, is required at the decisional stage of apoptosis. We recently identified serine 184 (S184) of Bax as a critical functional switch controlling its proapoptotic activity. Here, we employed the structural pocket around S184 as a docking site to screen the NCI library of small molecules using the UCSF-DOCK program suite. Three compounds, small molecule Bax agonists SMBA1, SMBA2 and SMBA3, induce conformational changes in Bax by blocking S184 phosphorylation, facilitating Bax insertion into mitochondrial membranes and forming Bax oligomers. The latter leads to cytochrome c release and apoptosis in human lung cancer cells, which occurs in a Bax- but not Bak-dependent fashion. SMBA1 potently suppresses lung tumor growth via apoptosis by selectively activating Bax in vivo without significant normal tissue toxicity. Development of Bax agonists as a new class of anti-cancer drugs offers a strategy for the treatment of lung cancer and other Bax-expressing malignancies. PMID:25230299

  14. Muscarinic Type 3 Receptor Induces Cytoprotective Signaling in Salivary Gland Cells through Epidermal Growth Factor Receptor Transactivation

    PubMed Central

    Kajiya, Mikihito; Ichimonji, Isao; Min, Christine; Zhu, Tongbo; Jin, Jun-O; Yu, Qing; Almazrooa, Soulafa A.; Cha, Seunghee

    2012-01-01

    Muscarinic type 3 receptor (M3R) plays a pivotal role in the induction of glandular fluid secretions. Although M3R is often the target of autoantibodies in Sjögren's syndrome (SjS), chemical agonists for M3R are clinically used to stimulate saliva secretion in patients with SjS. Aside from its activity in promoting glandular fluid secretion, however, it is unclear whether activation of M3R is related to other biological events in SjS. This study aimed to investigate the cytoprotective effect of chemical agonist-mediated M3R activation on apoptosis induced in human salivary gland (HSG) cells. Carbachol (CCh), a muscarinic receptor-specific agonist, abrogated tumor necrosis factor α/interferon γ-induced apoptosis through pathways involving caspase 3/7, but its cytoprotective effect was decreased by a M3R antagonist, a mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (ERK) inhibitor, a phosphatidylinositol 3-kinase/Akt inhibitor, or an epidermal growth factor receptor (EGFR) inhibitor. Ligation of M3R with CCh transactivated EGFR and phosphorylated ERK and Akt, the downstream targets of EGFR. Inhibition of intracellular calcium release or protein kinase C δ, both of which are involved in the cell signaling of M3R-mediated fluid secretion, did not affect CCh-induced ERK or Akt phosphorylation. CCh stimulated Src phosphorylation and binding to EGFR. A Src inhibitor attenuated the CCh/M3R-induced cytoprotective effect and EGFR transactivation cascades. Overall, these results indicated that CCh/M3R induced transactivation of EGFR through Src activation leading to ERK and Akt phosphorylation, which in turn suppressed caspase 3/7-mediated apoptotic signals in HSG cells. This study, for the first time, proposes that CCh-mediated M3R activation can promote not only fluid secretion but also survival of salivary gland cells in the inflammatory context of SjS. PMID:22511543

  15. Physical Chemistry to the Rescue: Differentiating Nicotinic and Cholinergic Agonists

    ERIC Educational Resources Information Center

    King, Angela G.

    2005-01-01

    Researches suggest that two agonists can bind to the same binding site of an important transmembrane protein and elicit a biological response through strikingly different binding interactions. Evidence is provided which suggests two possible types of nicotinic acetylcholine receptor agonist binding like acetlycholine (cholinergic) or like nicotine…

  16. GLP-1 agonist treatment: implications for diabetic retinopathy screening.

    PubMed

    Varadhan, Lakshminarayanan; Humphreys, Tracy; Hariman, Christian; Walker, Adrian B; Varughese, George I

    2011-12-01

    Rapid improvement in glycaemic control induced by GLP-1 agonist therapy could be yet another illustration of transient or permanent progression of diabetic retinopathy, similar to documented examples such as pregnancy and continuous subcutaneous insulin infusion. Specific guidelines would be needed to monitor this paradoxical phenomenon during treatment with GLP-1 agonists. PMID:21906831

  17. TOXICITY OF AHR AGONISTS TO FISH EARLY LIFE STAGES

    EPA Science Inventory

    Fish early life stages are exceptionally sensitive to the lethal toxicity of chemicals that act as arylhydrocarbon receptor (AhR) agonists. Toxicity characterizations based on 2,3,7,8-tetrachlorodibenzo-p-dioxin, generally the most potent AhR agonist, support the toxicity equiva...

  18. Interactions between cannabinoid receptor agonists and mu opioid receptor agonists in rhesus monkeys discriminating fentanyl.

    PubMed

    Maguire, David R; France, Charles P

    2016-08-01

    Cannabinoid receptor agonists such as delta-9-tetrahydrocannabinol (Δ(9)-THC) enhance some (antinociceptive) but not other (positive reinforcing) effects of mu opioid receptor agonists, suggesting that cannabinoids might be combined with opioids to treat pain without increasing, and possibly decreasing, abuse. The degree to which cannabinoids enhance antinociceptive effects of opioids varies across drugs insofar as Δ(9)-THC and the synthetic cannabinoid receptor agonist CP55940 increase the potency of some mu opioid receptor agonists (e.g., fentanyl) more than others (e.g., nalbuphine). It is not known whether interactions between cannabinoids and opioids vary similarly for other (abuse-related) effects. This study examined whether Δ(9)-THC and CP55940 differentially impact the discriminative stimulus effects of fentanyl and nalbuphine in monkeys (n=4) discriminating 0.01mg/kg of fentanyl (s.c.) from saline. Fentanyl (0.00178-0.0178mg/kg) and nalbuphine (0.01-0.32mg/kg) dose-dependently increased drug-lever responding. Neither Δ(9)-THC (0.032-1.0mg/kg) nor CP55940 (0.0032-0.032mg/kg) enhanced the discriminative stimulus effects of fentanyl or nalbuphine; however, doses of Δ(9)-THC and CP55940 that shifted the nalbuphine dose-effect curve markedly to the right and/or down were less effective or ineffective in shifting the fentanyl dose-effect curve. The mu opioid receptor antagonist naltrexone (0.032mg/kg) attenuated the discriminative stimulus effects of fentanyl and nalbuphine similarly. These data indicate that the discriminative stimulus effects of nalbuphine are more sensitive to attenuation by cannabinoids than those of fentanyl. That the discriminative stimulus effects of some opioids are more susceptible to modification by drugs from other classes has implications for developing maximally effective therapeutic drug mixtures with reduced abuse liability. PMID:27184925

  19. A combustion setup to precisely reference δ13C and δ2H isotope ratios of pure CH4 to produce isotope reference gases of δ13C-CH4 in synthetic air

    NASA Astrophysics Data System (ADS)

    Sperlich, P.; Guillevic, M.; Buizert, C.; Jenk, T. M.; Sapart, C. J.; Schaefer, H.; Popp, T. J.; Blunier, T.

    2012-09-01

    Isotope records of atmospheric CH4 can be used to infer changes in the biogeochemistry of CH4. One factor currently limiting the quantitative interpretation of such changes are uncertainties in the isotope measurements stemming from the lack of a unique isotope reference gas, certified for δ13C-CH4 or δ2H-CH4. We present a method to produce isotope reference gases for CH4 in synthetic air that are precisely anchored to the VPDB and VSMOW scales and have δ13C-CH4 values typical for the modern and glacial atmosphere. We quantitatively combusted two pure CH4 gases from fossil and biogenic sources and determined the δ13C and δ2H values of the produced CO2 and H2O relative to the VPDB and VSMOW scales within a very small analytical uncertainty of 0.04‰ and 0.7‰, respectively. We found isotope ratios of -39.56‰ and -56.37‰ for δ13C and -170.1‰ and -317.4‰ for δ2H in the fossil and biogenic CH4, respectively. We used both CH4 types as parental gases from which we mixed two filial CH4 gases. Their δ13C was determined to be -42.21‰ and -47.25‰ representing glacial and present atmospheric δ13C-CH4. The δ2H isotope ratios of the filial CH4 gases were found to be -193.1‰ and -237.1‰, respectively. Next, we mixed aliquots of the filial CH4 gases with ultrapure N2/O2 (CH4 ≤ 2 ppb) producing two isotope reference gases of synthetic air with CH4 mixing ratios near atmospheric values. We show that our method is reproducible and does not introduce isotopic fractionation for δ13C within the uncertainties of our detection limit (we cannot conclude this for δ2H because our system is currently not prepared for δ2H-CH4 measurements in air samples). The general principle of our method can be applied to produce synthetic isotope reference gases targeting δ2H-CH4 or other gas species.

  20. A combustion setup to precisely reference δ13C and δ2H isotope ratios of pure CH4 to produce isotope reference gases of δ13C-CH4 in synthetic air

    NASA Astrophysics Data System (ADS)

    Sperlich, P.; Guillevic, M.; Buizert, C.; Jenk, T. M.; Sapart, C. J.; Schaefer, H.; Blunier, T.

    2012-05-01

    Isotope records of atmospheric CH4 can be used to infer changes in the biochemistry of CH4. One factor limiting quantitative estimates of changes in the biogeochemistry of CH4 are the uncertainties of the isotope measurements due to the lack of a unique isotope reference gas, certified for δ13C-CH4 or δ2H-CH4. We present a method to produce isotope reference gases for CH4 in synthetic airs that are precisely anchored to the VPDB and VSMOW scale and contain δ13C-CH4 values typical for the modern and glacial atmosphere. We quantitatively combusted two pure CH4 gases from fossil and biogenic sources and determined the δ13C and δ2H values of the produced CO2 and H2O relative to the VPDB and VSMOW scale within a very small analytical uncertainty of 0.04‰ and 0.7‰, respectively. We found isotope ratios of -39.56‰ and -56.37‰ for δ13C and -170.1‰ and -317.4‰ for δ2H in the fossil and biogenic CH4, respectively. We used both CH4 types as parental gases from which we mixed two filial CH4 gases. Their δ13C was determined to be -42.21‰ and -47.25‰, representing glacial and present atmospheric δ13C-CH4. The δ2H isotope ratios of the filial CH4 gases were found with -193.1‰ and -237.1‰, respectively. Next, we mixed aliquots of the filial CH4 gases with ultrapure N2/O2 (CH4 ≤ 2 ppb) producing two isotope reference gases of synthetic air with CH4 mixing ratios near atmospheric values. We show that our method is reproducible and does not introduce isotopic fractionation for δ13C within the uncertainties of our detection limit (we cannot conclude this for δ2H because our system is currently not prepared for δ2H-CH4 measurements in air samples). The general principle of our method can be applied to produce synthetic isotope reference gases targeting δ2H-CH4 or other gas species.

  1. The cardiovascular effects of peroxisome proliferator-activated receptor agonists.

    PubMed

    Friedland, Sayuri N; Leong, Aaron; Filion, Kristian B; Genest, Jacques; Lega, Iliana C; Mottillo, Salvatore; Poirier, Paul; Reoch, Jennifer; Eisenberg, Mark J

    2012-02-01

    Although peroxisome proliferator-activated receptor agonists are prescribed to improve cardiovascular risk factors, their cardiovascular safety is controversial. We therefore reviewed the literature to identify landmark randomized controlled trials evaluating the effect of peroxisome proliferator-activated receptor gamma agonists (pioglitazone and rosiglitazone), alpha agonists (fenofibrate and gemfibrozil), and pan agonists (bezafibrate, muraglitazar, ragaglitazar, tesaglitazar, and aleglitazar) on cardiovascular outcomes. Pioglitazone may modestly reduce cardiovascular events but also may increase the risk of bladder cancer. Rosiglitazone increases the risk of myocardial infarction and has been withdrawn in European and restricted in the United States. Fibrates improve cardiovascular outcomes only in select subgroups: fenofibrate in diabetic patients with metabolic syndrome, gemfibrozil in patients with dyslipidemia, and bezafibrate in patients with diabetes or metabolic syndrome. The cardiovascular safety of the new pan agonist aleglitazar, currently in phase II trials, remains to be determined. The heterogenous effects of peroxisome proliferator-activated receptor agonists to date highlight the importance of postmarketing surveillance. The critical question of why peroxisome proliferator-activated receptor agonists seem to improve cardiovascular risk factors without significantly improving cardiovascular outcomes requires further investigation. PMID:22269613

  2. [PPAR receptors and insulin sensitivity: new agonists in development].

    PubMed

    Pégorier, J-P

    2005-04-01

    Thiazolidinediones (or glitazones) are synthetic PPARgamma (Peroxisome Proliferator-Activated Receptors gamma) ligands with well recognized effects on glucose and lipid metabolism. The clinical use of these PPARgamma agonists in type 2 diabetic patients leads to an improved glycemic control and an inhanced insulin sensitivity, and at least in animal models, to a protective effect on pancreatic beta-cell function. However, they can produce adverse effects, generally mild or moderate, but some of them (mainly peripheral edema and weight gain) may conduct to treatment cessation. Several pharmacological classes are currently in pre-clinical or clinical development, with the objective to retain the beneficial metabolic properties of PPARgamma agonists, either alone or in association with the PPARalpha agonists (fibrates) benefit on lipid profile, but devoid of the side-effects on weight gain and fluid retention. These new pharmacological classes: partial PPARgamma agonists, PPARgamma antagonists, dual PPARalpha/PPARgamma agonists, pan PPARalpha/beta(delta)/gamma agonists, RXR receptor agonists (rexinoids), are presented in this review. Main results from in vitro cell experiments and animal model studies are discussed, as well as the few published short-term studies in type 2 diabetic patients. PMID:15959400

  3. Transient infrared absorption of t-CH3C(O)OO, c-CH3C(O)OO, and α-lactone recorded in gaseous reactions of CH3CO and O2

    NASA Astrophysics Data System (ADS)

    Chen, Sun-Yang; Lee, Yuan-Pern

    2010-03-01

    A step-scan Fourier-transform infrared spectrometer coupled with a multipass absorption cell was utilized to monitor the transient species produced in gaseous reactions of CH3CO and O2; IR absorption spectra of CH3C(O)OO and α-lactone were observed. Absorption bands with origins at 1851±1, 1372±2, 1169±6, and 1102±3 cm-1 are attributed to t-CH3C(O)OO, and those at 1862±3, 1142±4, and 1078±6 cm-1 are assigned to c-CH3C(O)OO. A weak band near 1960 cm-1 is assigned to α-lactone, cyc-CH2C(O)O, a coproduct of OH. These observed rotational contours agree satisfactorily with simulated bands based on predicted rotational parameters and dipole derivatives, and observed vibrational wavenumbers agree with harmonic vibrational wavenumbers predicted with B3LYP/aug-cc-pVDZ density-functional theory. The observed relative intensities indicate that t-CH3C(O)OO is more stable than c-CH3C(O)OO by 3±2 kJ mol-1. Based on these observations, the branching ratio for the OH+α-lactone channel of the CH3CO+O2 reaction is estimated to be 0.04±0.01 under 100 Torr of O2 at 298 K. A simple kinetic model is employed to account for the decay of CH3C(O)OO.

  4. Antifertility effects of luteinizing hormone-releasing hormone (LHRH) agonists.

    PubMed

    Labrie, F; Bélanger, A; Kelly, P A; Séguin, C; Cusan, L; Lefebvre, F A; Reeves, J J; Lemay, A; Faure, N; Gourdeau, Y; Raynaud, J P

    1981-01-01

    This paper reviews the mechanisms responsible for the antifertility effects of luteinizing hormone-releasing hormone (LHRH) agonists. Large doses of the LHRH agonist LHRH-EA lead to a marked reduction of testicular and secondary sex organ weight, LH receptor levels, and plasma testosterone concentration. A marked inhibition of basal testicular and testosterone concentrations is obtained after daily administration of the LHRH agonists at doses greater than 10 ng. Treatment with low doses of the LHRH agonist can lead to an increased steroidogenic response to LH. Treatment with low doses of LHRH agonists could stimulate Leydig cell function while high doses are history. A study of the effects of longterm treatment with an LHRH agonsist on spermatogenesis revelaed that testis, prostate, and seminal vesicle weight decreased and plasma LH and FSH levels increased over 12 weeks. Comparison of the effects of increasing doses of LHRH agonist on testicular and ovarian gonadotropin receptors and steroidogenesis in male rats indicates that single or repeated administration of LHRH agonists can lead to loss of testicular LH receptors in the absence of the pituitary gland. The loss of ovarian gonadotropin receptors in female rats is also investigated. Antifertility effects of LHRH ethylamide are accompanied by a marked loss of LH/hCG and FSH receptors in ovarian tissue. The injection of 1,3, or 10 ng LHRH-EA in intact rats has no significant effect on ovarian LH receptor levels. A study of the direct action of LHRH agonists at the ovarian level demonstrates a close relationship between the binding activity of a large series of LHRH agonists and antagonists in the anterior pituitary gland and the ovary. Inhibition of testicular steroidogenesis in man by treatment with a potent LHRH agonist is also demonstrated. Intranasal administration of LHRH ethylamide has luteolytic effects in normal women. Daily administration of LHRH-EA inhibited ovulation in all but 2 of 89 treatment

  5. [Effects of GLP-1 receptor agonists on carbohydrate metabolism control].

    PubMed

    Fernández-García, José Carlos; Colomo, Natalia; Tinahones, Francisco José

    2014-09-01

    Glucagon-like peptide-1 (GLP-1) receptor agonists are a new group of drugs for the treatment of type 2 diabetes mellitus (DM2). In the present article, we review the available evidence on the efficacy of GLP-1 receptor agonists as glucose-lowering agents, their place in therapeutic algorithms, and the clinical factors associated with a favorable treatment response. Finally, we describe the clinical characteristics of patients who may benefit from these drugs.

  6. [Effects of GLP-1 receptor agonists on carbohydrate metabolism control].

    PubMed

    Fernández-García, José Carlos; Colomo, Natalia; Tinahones, Francisco José

    2014-01-01

    Glucagon-like peptide-1 (GLP-1) receptor agonists are a new group of drugs for the treatment of type 2 diabetes mellitus (DM2). In the present article, we review the available evidence on the efficacy of GLP-1 receptor agonists as glucose-lowering agents, their place in therapeutic algorithms, and the clinical factors associated with a favorable treatment response. Finally, we describe the clinical characteristics of patients who may benefit from these drugs.

  7. [Effects of GLP-1 receptor agonists on carbohydrate metabolism control].

    PubMed

    Fernández-García, José Carlos; Colomo, Natalia; Tinahones, Francisco José

    2014-09-01

    Glucagon-like peptide-1 (GLP-1) receptor agonists are a new group of drugs for the treatment of type 2 diabetes mellitus (DM2). In the present article, we review the available evidence on the efficacy of GLP-1 receptor agonists as glucose-lowering agents, their place in therapeutic algorithms, and the clinical factors associated with a favorable treatment response. Finally, we describe the clinical characteristics of patients who may benefit from these drugs. PMID:25437461

  8. [Effects of GLP-1 receptor agonists on carbohydrate metabolism control].

    PubMed

    Fernández-García, José Carlos; Colomo, Natalia; Tinahones, Francisco José

    2014-01-01

    Glucagon-like peptide-1 (GLP-1) receptor agonists are a new group of drugs for the treatment of type 2 diabetes mellitus (DM2). In the present article, we review the available evidence on the efficacy of GLP-1 receptor agonists as glucose-lowering agents, their place in therapeutic algorithms, and the clinical factors associated with a favorable treatment response. Finally, we describe the clinical characteristics of patients who may benefit from these drugs. PMID:25326839

  9. PPAR dual agonists: are they opening Pandora's Box?

    PubMed

    Balakumar, Pitchai; Rose, Madhankumar; Ganti, Subrahmanya S; Krishan, Pawan; Singh, Manjeet

    2007-08-01

    Cardiovascular disorders are the major cause of mortality in patients of diabetes mellitus. Peroxisome proliferator activated receptors (PPARs) are ligand-activated transcription factors of nuclear hormone receptor superfamily comprising of three subtypes such as PPARalpha, PPARgamma and PPARdelta/beta. Activation of PPARalpha reduces triglycerides and involves in regulation of energy homeostasis. Activation of PPARgamma causes insulin sensitization and enhances glucose metabolism, whereas activation of PPARdelta enhances fatty acid metabolism. Current therapeutic strategies available for the treatment of diabetes do not inhibit the associated secondary cardiovascular complications. Hence, the development of multimodal drugs which can reduce hyperglycemia and concomitantly inhibit the progression of secondary cardiovascular complications may offer valuable therapeutic option. Several basic and clinical studies have exemplified the beneficial effects of PPARalpha and PPARgamma ligands in preventing the cardiovascular risks. The PPARalpha/gamma dual agonists are developed to increase insulin sensitivity and simultaneously prevent diabetic cardiovascular complications. Such compounds are under clinical trials and proposed for treatment of Type II diabetes with secondary cardiovascular complications. However, PPARalpha/gamma dual agonists such as muraglitazar, tesaglitazar and ragaglitazar have been noted to produce several cardiovascular risks and carcinogenicity, which raised number of questions about the clinical applications of dual agonists in diabetes and its associated complications. The ongoing basic studies have elucidated the cardio protective role of PPARdelta. Therefore, further studies are on the track to develop PPARalpha/delta and PPAR gamma/delta dual agonists and PPARalpha/gamma/delta pan agonists for the treatment of diabetic cardiovascular complications. The present review critically analyzes the protective and detrimental effect of PPAR agonists in

  10. Identification of M-CSF agonists and antagonists

    SciTech Connect

    Pandit, Jayvardhan; Jancarik, Jarmila; Kim, Sung-Hou; Koths, Kirston; Halenbeck, Robert; Fear, Anna Lisa; Taylor, Eric; Yamamoto, Ralph; Bohm, Andrew

    2000-02-15

    The present invention is directed to methods for crystallizing macrophage colony stimulating factor. The present invention is also directed to methods for designing and producing M-CSF agonists and antagonists using information derived from the crystallographic structure of M-CSF. The invention is also directed to methods for screening M-CSF agonists and antagonists. In addition, the present invention is directed to an isolated, purified, soluble and functional M-CSF receptor.

  11. Pharmacogenetics of beta2 adrenergic receptor agonists in asthma management.

    PubMed

    Ortega, V E

    2014-07-01

    Beta2 (β2) adrenergic receptor agonists (beta agonists) are a commonly prescribed treatment for asthma despite the small increase in risk for life-threatening adverse responses associated with long-acting beta agonist (LABA). The concern for life-threatening adverse effects associated with LABA and the inter-individual variability of therapeutic responsiveness to LABA-containing combination therapies provide the rationale for pharmacogenetic studies of beta agonists. These studies primarily evaluated genes within the β2-adrenergic receptor and related pathways; however, recent genome-wide studies have identified novel loci for beta agonist response. Recent studies have identified a role for rare genetic variants in determining beta agonist response and, potentially, the risk for rare, adverse responses to LABA. Before genomics research can be applied to the development of genetic profiles for personalized medicine, it will be necessary to continue adapting to the analysis of an increasing volume of genetic data in larger cohorts with a combination of analytical methods and in vitro studies.

  12. Pairwise agonist scanning predicts cellular signaling responses to combinatorial stimuli.

    PubMed

    Chatterjee, Manash S; Purvis, Jeremy E; Brass, Lawrence F; Diamond, Scott L

    2010-07-01

    Prediction of cellular response to multiple stimuli is central to evaluating patient-specific clinical status and to basic understanding of cell biology. Cross-talk between signaling pathways cannot be predicted by studying them in isolation and the combinatorial complexity of multiple agonists acting together prohibits an exhaustive exploration of the complete experimental space. Here we describe pairwise agonist scanning (PAS), a strategy that trains a neural network model based on measurements of cellular responses to individual and all pairwise combinations of input signals. We apply PAS to predict calcium signaling responses of human platelets in EDTA-treated plasma to six different agonists (ADP, convulxin, U46619, SFLLRN, AYPGKF and PGE(2)) at three concentrations (0.1, 1 and 10 x EC(50)). The model predicted responses to sequentially added agonists, to ternary combinations of agonists and to 45 different combinations of four to six agonists (R = 0.88). Furthermore, we use PAS to distinguish between the phenotypic responses of platelets from ten donors. Training neural networks with pairs of stimuli across the dose-response regime represents an efficient approach for predicting complex signal integration in a patient-specific disease milieu. PMID:20562863

  13. Perception of specific trigeminal chemosensory agonists

    PubMed Central

    Frasnelli, J; Albrecht, J; Bryant, B; Lundström, JN

    2011-01-01

    The intranasal trigeminal system is a third chemical sense in addition to olfaction and gustation. As opposed to smell and taste, we still lack knowledge on the relationship between receptor binding and perception for the trigeminal system. We therefore investigated the sensitivity of the intranasal trigeminal system towards agonists of the trigeminal receptors TRPM8 and TRPA1 by assessing subjects’ ability to identify which nostril has been stimulated in a monorhinal stimulation design. We summed the number of correct identifications resulting in a lateralization score. Stimuli were menthol (activating TRPM8 receptors), eucalyptol (TRPM8), mustard oil (TRPA1) and two mixtures thereof (menthol/eucalyptol and menthol/mustard oil). In addition, we examined the relationship between intensity and lateralization scores and investigated whether intensity evaluation and lateralization scores of the mixtures show additive effects. All stimuli were correctly lateralized significantly above chance. Across subjects the lateralization scores for single compounds activating the same receptor showed a stronger correlation than stimuli activating different receptors. Although single compounds were isointense, the mixture of menthol and eucalyptol (activating only TRPM8) was perceived as weaker and was lateralized less accurately than the mixture of menthol and mustard oil (activating both TRPM8 and TRPA1) suggesting suppression effects in the former mixture. In conclusion, sensitivity of different subpopulations of trigeminal sensory neurons seems to be related, but only to a certain degree. The large coherence in sensitivity between various intranasal trigeminal stimuli suggests that measuring sensitivity to one single trigeminal chemical stimulus may be sufficient to generally assess the trigeminal system’s chemosensitivity. Further, for stimuli activating the same receptor a mixture suppression effect appears to occur similar to that observed in the other chemosensory

  14. Identification of Determinants Required for Agonistic and Inverse Agonistic Ligand Properties at the ADP Receptor P2Y12

    PubMed Central

    Schmidt, Philipp; Ritscher, Lars; Dong, Elizabeth N.; Hermsdorf, Thomas; Cöster, Maxi; Wittkopf, Doreen; Meiler, Jens

    2013-01-01

    The ADP receptor P2Y12 belongs to the superfamily of G protein–coupled receptors (GPCRs), and its activation triggers platelet aggregation. Therefore, potent antagonists, such as clopidogrel, are of high clinical relevance in prophylaxis and treatment of thromboembolic events. P2Y12 displays an elevated basal activity in vitro, and as such, inverse agonists may be therapeutically beneficial compared with antagonists. Only a few inverse agonists of P2Y12 have been described. To expand this limited chemical space and improve understanding of structural determinants of inverse agonist-receptor interaction, this study screened a purine compound library for lead structures using wild-type (WT) human P2Y12 and 28 constitutively active mutants. Results showed that ATP and ATP derivatives are agonists at P2Y12. The potency at P2Y12 was 2-(methylthio)-ADP > 2-(methylthio)-ATP > ADP > ATP. Determinants required for agonistic ligand activity were identified. Molecular docking studies revealed a binding pocket for the ATP derivatives that is bordered by transmembrane helices 3, 5, 6, and 7 in human P2Y12, with Y105, E188, R256, Y259, and K280 playing a particularly important role in ligand interaction. N-Methyl-anthraniloyl modification at the 3′-OH of the 2′-deoxyribose leads to ligands (mant-deoxy-ATP [dATP], mant-deoxy-ADP) with inverse agonist activity. Inverse agonist activity of mant-dATP was found at the WT human P2Y12 and half of the constitutive active P2Y12 mutants. This study showed that, in addition to ADP and ATP, other ATP derivatives are not only ligands of P2Y12 but also agonists. Modification of the ribose within ATP can result in inverse activity of ATP-derived ligands. PMID:23093496

  15. Identification of Potent, Selective P2Y-Purinoceptor Agonists: Structure–Activity Relationships for 2-Thioether Derivatives of Adenosine 5′-Triphosphate†

    PubMed Central

    Fischer, Bilha; Boyer, José L.; Hoyle, Charles H. V.; Ziganshin, Airat U.; Brizzolara, Antonia L.; Knight, Gillian E.; Zimmet, Jeffrey; Burnstock, Geoffrey; Harden, T. Kendall; Jacobson, Kenneth A.

    2012-01-01

    Study of P2-purinoceptor subtypes has been difficult due to the lack of potent and selective ligands. With the goal of developing high affinity P2-purinoceptor-selective agonists, we have synthesized a series of analogues of adenine nucleotides modified on the purine ring as chain-extended 2-thioethers or as N6-methyl-substituted compounds. Chemical functionality incorporated in the thioether moiety included cyanoalkyl, nitroaromatic, amino, thiol, cycloalkyl, n-alkyl, and olefinic groups. Apparent affinity of the compounds for P2Y-purinoceptors was established by measurement of P2Y-purinoceptor-promoted phospholipase C activity in turkey erythrocyte membranes and relaxation of carbachol-contracted smooth muscle in three different preparations (guinea pig taenia coil, rabbit aorta, and rabbit mesenteric artery). Activity at P2X-purinoceptors was established by measurement of contraction of rabbit saphenous artery and of the guinea pig vas deferens and urinary bladder. All 11 of the 2-thioethers of ATP stimulated the production of inositol phosphates with K0.5 values of 1.5–770 nM, with an (aminophenyl)ethyl derivative being most potent. Two adenosine diphosphate analogues were equipotent to the corresponding ATP analogues. Adenosine monophosphate analogues were full agonists, although generally 4 orders of magnitude less potent. ATP 2-thioethers displayed pD2 values in the range of 6–8 in smooth muscle assay systems for activity at P2Y-receptors. There was a significant correlation for the 2-thioether compounds between the pK0.5 values for inositol phosphate production and the pD2 values for relaxation mediated via the P2Y-purinoceptors in the guinea pig taenia coli, but not for the vascular P2Y-receptors or for the P2X-receptors. At P2X-receptors, no activity was observed in the rabbit saphenous artery, but variable degrees of activity were observed in the guinea pig vas deferens and bladder depending on distal substituents of the thioether moiety. N6-Methyl

  16. RXR Partial Agonist CBt-PMN Exerts Therapeutic Effects on Type 2 Diabetes without the Side Effects of RXR Full Agonists

    PubMed Central

    2012-01-01

    Treating insulin resistance and type 2 diabetes in rodents, currently known retinoid X receptor (RXR) agonists induce significant adverse effects. Here we introduce a novel RXR partial agonist CBt-PMN (11b), which shows a potent glucose-lowering effect and improvements of insulin secretion and glucose tolerance without the serious adverse effects caused by RXR full agonists. We suggest that RXR partial agonists may be a new class of antitype 2 diabetes drug candidates. PMID:24900488

  17. Dihydrocodeine/Agonists for Alcohol Dependents

    PubMed Central

    Ulmer, Albrecht; Müller, Markus; Frietsch, Bernhard

    2012-01-01

    Objective: Alcohol addiction too often remains insufficiently treated. It shows the same profile as severe chronic diseases, but no comparable, effective basic treatment has been established up to now. Especially patients with repeated relapses, despite all therapeutic approaches, and patients who are not able to attain an essential abstinence to alcohol, need a basic medication. It seems necessary to acknowledge that parts of them need any agonistic substance, for years, possibly lifelong. For >14 years, we have prescribed such substances with own addictive character for these patients. Methods: We present a documented best possible practice, no designed study. Since 1997, we prescribed Dihydrocodeine (DHC) to 102 heavily alcohol addicted patients, later, also Buprenorphine, Clomethiazole (>6 weeks), Baclofen, and in one case Amphetamine, each on individual indication. This paper focuses on the data with DHC, especially. The Clomethiazole-data has been submitted to a German journal. The number of treatments with the other substances is still low. Results: The 102 patients with the DHC treatment had 1367 medically assisted detoxifications and specialized therapies before! The 4 years-retention rate was 26.4%, including 2.8% successfully terminated treatments. In our 12-steps scale on clinical impression, we noticed a significant improvement from mean 3.7 to 8.4 after 2 years. The demand for medically assisted detoxifications in the 2 years remaining patients was reduced by 65.5%. Mean GGT improved from 206.6 U/l at baseline to 66.8 U/l after 2 years. Experiences with the other substances are similar but different in details. Conclusion: Similar to the Italian studies with GHB and Baclofen, we present a new approach, not only with new substances, but also with a new setting and much more trusting attitude. We observe a huge improvement, reaching an almost optimal, stable, long term status in around 1/4 of the patients already. Many further

  18. Honokiol: A non-adipogenic PPARγ agonist from nature☆

    PubMed Central

    Atanasov, Atanas G.; Wang, Jian N.; Gu, Shi P.; Bu, Jing; Kramer, Matthias P.; Baumgartner, Lisa; Fakhrudin, Nanang; Ladurner, Angela; Malainer, Clemens; Vuorinen, Anna; Noha, Stefan M.; Schwaiger, Stefan; Rollinger, Judith M.; Schuster, Daniela; Stuppner, Hermann; Dirsch, Verena M.; Heiss, Elke H.

    2013-01-01

    Background Peroxisome proliferator-activated receptor gamma (PPARγ) agonists are clinically used to counteract hyperglycemia. However, so far experienced unwanted side effects, such as weight gain, promote the search for new PPARγ activators. Methods We used a combination of in silico, in vitro, cell-based and in vivo models to identify and validate natural products as promising leads for partial novel PPARγ agonists. Results The natural product honokiol from the traditional Chinese herbal drug Magnolia bark was in silico predicted to bind into the PPARγ ligand binding pocket as dimer. Honokiol indeed directly bound to purified PPARγ ligand-binding domain (LBD) and acted as partial agonist in a PPARγ-mediated luciferase reporter assay. Honokiol was then directly compared to the clinically used full agonist pioglitazone with regard to stimulation of glucose uptake in adipocytes as well as adipogenic differentiation in 3T3-L1 pre-adipocytes and mouse embryonic fibroblasts. While honokiol stimulated basal glucose uptake to a similar extent as pioglitazone, it did not induce adipogenesis in contrast to pioglitazone. In diabetic KKAy mice oral application of honokiol prevented hyperglycemia and suppressed weight gain. Conclusion We identified honokiol as a partial non-adipogenic PPARγ agonist in vitro which prevented hyperglycemia and weight gain in vivo. General significance This observed activity profile suggests honokiol as promising new pharmaceutical lead or dietary supplement to combat metabolic disease, and provides a molecular explanation for the use of Magnolia in traditional medicine. PMID:23811337

  19. Modification of opiate agonist binding by pertussis toxin

    SciTech Connect

    Abood, M.E.; Lee, N.M.; Loh, H.H.

    1986-03-05

    Opiate agonist binding is decreased by GTP, suggesting the possible involvement of GTP binding proteins in regulation of opiate receptor binding. This possibility was addressed by asking whether pertussis toxin treatment, which results in ADP-ribosylation and modification of G proteins, would alter opiate agonist binding. The striatum was chosen for the initial brain area to be studied, since regulation of opiate action in this area had been shown to be modified by pertussis toxin. Treatment of striatal membranes with pertussis toxin results in up to a 55% decrease in /sup 3/(H)-DADLE binding as compared with membranes treated identically without toxin. This corresponds to a near complete ADP-ribosylation of both G proteins in the striatal membrane. The decrease in agonist binding appears to be due to an altered affinity of the receptor for agonist as opposed to a decrease in the number of sites. This effect of pertussis toxin on opiate agonist binding demonstrates the actual involvement of G proteins in regulation of opiate receptor binding.

  20. Sound production during agonistic behavior of male Drosophila melanogaster

    PubMed Central

    Jonsson, Thorin; Kravitz, Edward A

    2011-01-01

    Male Drosophila fruit flies acquire and defend territories in order to attract females for reproduction. Both, male-directed agonistic behavior and female-directed courtship consist of series of recurrent stereotypical components. Various studies demonstrated the importance of species-specific sound patterns generated by wing vibration as being critical for male courtship success. In this study we analyzed the patterns and importance of sound signals generated during agonistic interactions of male Drosophila melanogaster. In contrast to acoustic courtship signals that consist of sine and pulse patterns and are generated by one extended wing, agonistic signals lack sine-like components and are generally produced by simultaneous movements of both wings. Though intra-pulse oscillation frequencies (carrier frequency) are identical, inter-pulse intervals are twice as long and more variable in aggression signals than in courtship songs, where their precise temporal pattern serves species recognition. Acoustic signals accompany male agonistic interactions over their entire course but occur particularly often after tapping behavior which is a major way to identify the gender of the interaction partner. Since similar wing movements may either be silent or generate sound and wing movements with sound have a greater impact on the subsequent behavior of a receiver, sound producing wing movements seem to be generated intentionally to serve as a specific signal during fruit fly agonistic encounters. PMID:20953152

  1. Radiation therapy generates platelet-activating factor agonists

    PubMed Central

    Sahu, Ravi P.; Harrison, Kathleen A.; Weyerbacher, Jonathan; Murphy, Robert C.; Konger, Raymond L.; Garrett, Joy Elizabeth; Chin-Sinex, Helen Jan; Johnston, Michael Edward; Dynlacht, Joseph R.; Mendonca, Marc; McMullen, Kevin; Li, Gengxin; Spandau, Dan F.; Travers, Jeffrey B.

    2016-01-01

    Pro-oxidative stressors can suppress host immunity due to their ability to generate oxidized lipid agonists of the platelet-activating factor-receptor (PAF-R). As radiation therapy also induces reactive oxygen species, the present studies were designed to define whether ionizing radiation could generate PAF-R agonists and if these lipids could subvert host immunity. We demonstrate that radiation exposure of multiple tumor cell lines in-vitro, tumors in-vivo, and human subjects undergoing radiation therapy for skin tumors all generate PAF-R agonists. Structural characterization of radiation-induced PAF-R agonistic activity revealed PAF and multiple oxidized glycerophosphocholines that are produced non-enzymatically. In a murine melanoma tumor model, irradiation of one tumor augmented the growth of the other (non-treated) tumor in a PAF-R-dependent process blocked by a cyclooxygenase-2 inhibitor. These results indicate a novel pathway by which PAF-R agonists produced as a byproduct of radiation therapy could result in tumor treatment failure, and offer important insights into potential therapeutic strategies that could improve the overall antitumor effectiveness of radiation therapy regimens. PMID:26959112

  2. Radiation therapy generates platelet-activating factor agonists.

    PubMed

    Sahu, Ravi P; Harrison, Kathleen A; Weyerbacher, Jonathan; Murphy, Robert C; Konger, Raymond L; Garrett, Joy Elizabeth; Chin-Sinex, Helen Jan; Johnston, Michael Edward; Dynlacht, Joseph R; Mendonca, Marc; McMullen, Kevin; Li, Gengxin; Spandau, Dan F; Travers, Jeffrey B

    2016-04-12

    Pro-oxidative stressors can suppress host immunity due to their ability to generate oxidized lipid agonists of the platelet-activating factor-receptor (PAF-R). As radiation therapy also induces reactive oxygen species, the present studies were designed to define whether ionizing radiation could generate PAF-R agonists and if these lipids could subvert host immunity. We demonstrate that radiation exposure of multiple tumor cell lines in-vitro, tumors in-vivo, and human subjects undergoing radiation therapy for skin tumors all generate PAF-R agonists. Structural characterization of radiation-induced PAF-R agonistic activity revealed PAF and multiple oxidized glycerophosphocholines that are produced non-enzymatically. In a murine melanoma tumor model, irradiation of one tumor augmented the growth of the other (non-treated) tumor in a PAF-R-dependent process blocked by a cyclooxygenase-2 inhibitor. These results indicate a novel pathway by which PAF-R agonists produced as a byproduct of radiation therapy could result in tumor treatment failure, and offer important insights into potential therapeutic strategies that could improve the overall antitumor effectiveness of radiation therapy regimens. PMID:26959112

  3. Tolerance with beta 2-adrenoceptor agonists: time for reappraisal.

    PubMed Central

    Grove, A; Lipworth, B J

    1995-01-01

    1. In spite of the widespread use of beta 2-adrenoceptor agonists in the treatment of asthma controversy continues regarding their possible role in increasing asthma mortality and morbidity. There is however no evidence available to suggest that tolerance to the bronchodilator or anti-bronchoconstrictor effects of these drugs is responsible for the deleterious effects reported with the regular use of bronchodilators. 2. There is no conclusive evidence to suggest that tolerance develops to the bronchodilator effects of short-acting beta 2-adrenoceptor agonists. Tolerance does however appear to develop to the anti-bronchoconstrictor effects of these drugs. 3. With regard to the long-acting beta 2-adrenoceptor agonists, there is evidence to suggest that tolerance develops both to their anti-bronchoconstrictor, and bronchodilator effects. Tolerance was however demonstrated in the presence of improved symptom control, therefore the clinical relevance of this phenomenon is uncertain. 4. Systemic corticosteroids can modulate lymphocyte beta 2-adrenoceptor function both preventing, and reversing tolerance. The situation regarding the effects of systemic or inhaled corticosteroids on modulating bronchodilator responses in asthmatics is less clear. There is some evidence to suggest that inhaled corticosteroids are unable to prevent bronchodilator or systemic tolerance to long-acting beta 2-adrenoceptor agonists. 5. On the basis of the current evidence, the British Thoracic Society guidelines for the management of asthma appear appropriate with regard to their recommendations for the use of long-acting beta 2-adrenoceptor agonists. PMID:7742147

  4. Current issues with beta2-adrenoceptor agonists: historical background.

    PubMed

    Tattersfield, Anne E

    2006-01-01

    The discovery that dessicated adrenal glands had beneficial effects in asthma arose in 1900 following a vogue for studying organotherapy at the end of the 19th century. The adrenal hormone adrenaline was found to have sympathomimetic properties and was isolated and synthesized in 1901. The first nonselective beta-agonist, isoproterenol, was isolated in 1940, followed by the development of selective beta2-agonists in the 1960s and the introduction of the long-acting beta2-agonists in the 1990s. The introduction of beta2-selectivity reduced adverse effects, as did developments in inhaler technology that allowed subjects to inhale much smaller doses of drug selectively to the airways. The beta2-agonists are some of the more important drugs to have been developed in the 20th century. Excessive doses can cause problems, and attempts to maximize the benefit from beta2-agonists and to reduce adverse effects has led to considerable epidemiological, clinical, and mechanistic research over the last 50 yr.

  5. Confounding of the Comparative Safety of Prenatal Opioid Agonist Therapy

    PubMed Central

    Brogly, Susan B; Hahn, Kristen A; Diaz, Sonia Hernandez; Werler, Martha

    2016-01-01

    Prenatal opioid agonist therapy with methadone or buprenorphine prevents maternal illicit opioid use and withdrawal and improves pregnancy outcomes compared to heroin use alone. Historically, methadone has been the first-line opioid agonist therapy for pregnant opioid dependent women; in recent years buprenorphine has become first-line treatment for some opioid dependent pregnant women. While there is some evidence of better outcomes in neonates exposed to buprenorphine vs. methadone, the effect of confounding from differences in women who use buprenorphine and methadone has not been carefully examined in most studies. This review explores mechanisms by which confounding can arise in measuring associations between prenatal buprenorphine vs. methadone exposure on neonatal outcomes using a graphical approach, directed acyclic graphs. The goal of this paper is to facilitate better understanding of the factors influencing neonatal abstinence syndrome and accurate assessment of the comparative safety of opioid agonist therapies on the neonate. PMID:27547489

  6. Adenosine receptor agonists for promotion of dermal wound healing

    PubMed Central

    Valls, María D.; Cronstein, Bruce N.; Montesinos, M. Carmen

    2009-01-01

    Wound healing is a dynamic and complex process that involves a well coordinated, highly regulated series of events including inflammation, tissue formation, revascularization and tissue remodeling. However, this orderly sequence is impaired in certain pathophysiological conditions such as diabetes mellitus, venous insufficiency, chronic glucocorticoid use, aging and malnutrition. Together with proper wound care, promotion of the healing process is the primary objective in the management of chronic poorly healing wounds. Recent studies have demonstrated that A2A adenosine receptor agonists promote wound healing in normal and diabetic animals and one such agonist, Sonedenoson, is currently being evaluated as a prospective new therapy of diabetic foot ulcers. We will review the mechanisms by which adenosine receptor activation affects the function of the cells and tissues that participate in wound healing, emphasizing the potential beneficial impact of adenosine receptor agonists in diabetic impaired healing. PMID:19041853

  7. Design, evaluation, and comparison of ghrelin receptor agonists and inverse agonists as suitable radiotracers for PET imaging.

    PubMed

    Chollet, Constance; Bergmann, Ralf; Pietzsch, Jens; Beck-Sickinger, Annette G

    2012-04-18

    Ghrelin agonist and inverse agonist radiotracers, suitable for positron emission tomography (PET), were developed to study the behavior of ghrelin receptor ligands in vivo and for further design of druggable peptides. The target peptides were synthesized on solid support and conjugated to the bifunctional chelator 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid (NODAGA), which is known to form a stable complex with Ga(3+). Complexation with (68)Ga could be achieved under mild conditions and led to radiotracers with high radiochemical purity and specific activity. The biological activity of the radiotracers was evaluated in vitro by an inositol phosphate turnover assay. Pharmacokinetic profile and metabolic stability of the (68)Ga-NODAGA-radiotracers were investigated by small animal PET in rodent. Ghrelin derived agonists presented very high kidney accumulation, negligible tissue distribution, fast blood clearance, and poor stability in blood. Contrarily, the inverse agonist radiotracer exhibited very high stability in blood, large diffusion in tissues, reasonable kidney and liver metabolism, and slow blood clearance. This pharmacokinetic profile makes the ghrelin inverse agonist motif KwFwLL-CONH(2) suitable for further development of radiotracers and a promising lead to design peptide-based therapeutics against obesity. PMID:22372770

  8. Agonist treatment in opioid use: advances and controversy.

    PubMed

    Viswanath, Biju; Chand, Prabhat; Benegal, Vivek; Murthy, Pratima

    2012-06-01

    Opioid dependence is a chronic relapsing condition which requires comprehensive care; pharmacological agents form the mainstay of its long term treatment. The two most popular approaches are the harm reduction method using agonists and the complete abstinence method using antagonists. Currently, particularly from the harm minimization perspective and the low feasibility of an abstinence based approach, there is an increasing trend toward agonist treatment. The use of buprenorphine has gained popularity in view of its safety profile and the availability of the buprenorphine-naloxone combination has made it popular as a take-home treatment. This review outlines the pharmacological advances and controversies in this area. PMID:22813654

  9. Insect Nicotinic Receptor Agonists as Flea Adulticides in Small Animals

    PubMed Central

    Vo, Dai Tan; Hsu, Walter H.; Martin, Richard J.

    2013-01-01

    Fleas are significant ectoparasites of small animals. They can be a severe irritant to animals and serve as a vector for a number of infectious diseases. In this article, we discuss the pharmacological characteristics of four insect nicotinic acetylcholine receptor (nAChR) agonists used as fleacides in dogs and cats, which include three neonicotinoids (imidacloprid, nitenpyram, and dinotefuran) and spinosad. Insect nAChR agonists are one of the most important new classes of insecticides, which are used to control sucking insects both on plants and on companion animals. These new compounds provide a new approach for practitioners to safely and effectively eliminate fleas. PMID:20646191

  10. Beta2-agonist extraction procedures for chromatographic analysis.

    PubMed

    dos Ramos, F J

    2000-06-01

    Normally, different procedures were necessary to prepare sample matrices for chromatographic determination of beta2-agonists. The present review includes sampling, pre-treatment and extraction/purification for urine, plasma, liver, meat, feeds, hair and milk powder, as previous steps for chromatographic analysis of beta2-agonists. Six methodologies were especially revised for extraction/purification namely, liquid-liquid extraction, solid-phase extraction (SPE), matrix solid-phase dispersion, immunoaffinity chromatography, dialysis and supercritical fluid extraction. SPE was discussed in detail and five mechanisms were described: adsorption, apolar, polar, ion-exchange and mixed phase. A brief conclusion in this field was also outlined.

  11. An unprecedented up-field shift in the 13C NMR spectrum of the carboxyl carbons of the lantern-type dinuclear complex TBA[Ru2(O2CCH3)4Cl2] (TBA+ = tetra(n-butyl)ammonium cation).

    PubMed

    Hiraoka, Yuya; Ikeue, Takahisa; Sakiyama, Hiroshi; Guégan, Frédéric; Luneau, Dominique; Gillon, Béatrice; Hiromitsu, Ichiro; Yoshioka, Daisuke; Mikuriya, Masahiro; Kataoka, Yusuke; Handa, Makoto

    2015-08-14

    A large up-field shift (-763 ppm) has been observed for the carboxyl carbons of the dichlorido complex TBA[Ru(2)(O(2)CCH(3))(4)Cl(2)] (TBA(+) = tetra(n-butyl)ammonium cation) in the (13)C NMR spectrum (CD(2)Cl(2) at 25 °C). The DFT calculations showed spin delocalization from the paramagnetic Ru(2)(5+) core to the ligands, in agreement with the large up-field shift.

  12. Infrared laser and Fourier transform spectroscopy of CCH: A highly excited bending vibration of the X ˜ 2Σ+ state and unique Renner-Teller levels of the A ˜ 2 Π state

    NASA Astrophysics Data System (ADS)

    Tokaryk, D. W.; Vervloet, M.; Phi, Tân-Trào

    2015-04-01

    New infrared bands of the linear carbon chain radical CCH are reported: X ˜ (0140 0)2Σ+ - X ˜ (000 0)2Σ+, recorded with a near-infrared diode laser spectrometer, and A ˜ (0 1 0) 22 Δ - X ˜ (011 0)2 Π, A ˜ (0 2 0) 32 Φ - X ˜ (022 0)2 Δ and A ˜ (0 3 0) 42 Γ - X ˜ (033 0)2 Φ, recorded in emission with a Fourier transform spectrometer. All of the upper levels in the transitions appear to be strongly affected by interactions with other levels. The data demonstrate the excellence of calculations by Tarroni and Carter (2003), which determine the upper state level positions, spin-orbit splitting A, and rotational parameter B to a remarkable level of accuracy, considering the very complex nature of the interactions between the X ˜ 2Σ+ and A ˜ 2 Π electronic states in the regions spanned by the observed levels.

  13. Reactions of vanadium dioxide molecules with acetylene: infrared spectra of VO2(η(2)-C2H2)(x) (x = 1, 2) and OV(OH)CCH in solid neon.

    PubMed

    Zhou, Xiaojie; Chen, Mohua; Zhou, Mingfei

    2013-07-01

    Reactions of vanadium dioxide molecules with acetylene have been studied by matrix isolation infrared spectroscopy. Reaction intermediates and products are identified on the basis of isotopic substitutions as well as density functional frequency calculations. Ground state vanadium dioxide molecule reacts with acetylene in forming the side-on-bonded VO2(η(2)-C2H2) and VO2(η(2)-C2H2)2 complexes spontaneously on annealing in solid neon. The VO2(η(2)-C2H2) complex is characterized to have a (2)B2 ground state with C2v symmetry, whereas the VO2(η(2)-C2H2)2 complex has a (2)A ground state with C2 symmetry. The VO2(η(2)-C2H2) and VO2(η(2)-C2H2)2 complexes are photosensitive. The VO2(η(2)-C2H2) complex rearranges to the OV(OH)CCH molecule upon UV-vis light excitation.

  14. Long-term exposure to [Cr3O(O2CCH2CH3)6(H2O)3]+ in Wistar rats fed normal or high-fat diets does not alter glucose metabolism

    PubMed Central

    Herring, Betty J.; Logsdon, Amanda L.; Lockard, Jarrett E.; Miller, Brittany M.; Kim, Hanna; Calderon, Eric A.; Vincent, John B.; Bailey, Melissa M.

    2013-01-01

    The essentiality of chromium(III) has been the subject of much debate, particularly in healthy subjects. Chromium(III)-containing supplements are widely used for body mass loss, building of lean muscle mass, and improving glucose and lipid metabolism. [Cr3O(O2CCH2CH3)6(H2O)3]+, Cr3, is one of the most-studied chromium nutritional supplements. The current study evaluates the effects of long-term (15 months) supplementation with Cr3 on body mass and glucose metabolism in Wistar rats on traditional and cafeteria-style (high fat, high carbohydrate) diets. Male Wistar rats were randomly assigned to one of four treatment groups: 1) control diet (milled Harlan Teklad LM-485 rodent diet), 2) control diet + 1 mg Cr3/kg body mass/day, 3) a cafeteria-style (CAF) diet (high fat, high carbohydrate), or 4) CAF diet + 1 mg Cr3/kg/day. Cr3 supplementation had no effect on fasting blood glucose levels or blood glucose levels in response to glucose and insulin challenges. Rats consuming the CAF + Cr3 diet tended to have a significantly higher body mass than rats consuming the CAF diet, but necropsy results showed no difference in visceral fat or body wall thickness between groups. These data suggest that long-term Cr3 supplementation does not significantly affect body mass in rats consuming a normal diet or glucose levels or metabolism in rats consuming either diet. PMID:23271681

  15. The emerging therapeutic roles of κ-opioid agonists.

    PubMed

    Jones, Mark R; Kaye, Alan D; Kaye, Aaron J; Urman, Richard D

    2016-01-01

    The current practice of μ-opioid receptor agonists such as morphine as the primary means of acute and chronic pain relief has several dangerous consequences that limit their effectiveness, including respiratory depression, gastrointestinal motility inhibition, addiction, tolerance, and abuse. Several other opioid receptors, notably the μ-opioid (KOP) receptor, have long been known to play a role in pain relief. Recent discoveries and advancements in laboratory techniques have allowed significant developments of KOP agonists as potential novel therapies for pain relief and other pathological processes. These drugs exhibit none of the classic opioid adverse effects and have displayed pronounced analgesia in several different scenarios. New formulations since 2014 have unveiled increased oral bioavailability, exceptional peripheral versus central selectivity, and a positive safety profile. Continued refinements of established μ-opioid agonist formulations have virtually eliminated the centrally mediated side effects of dysphoria and sedation that limited the applicability of previous KOP agonists. Further research is required to better elucidate the potential of these compounds in pain management, as well as in the mediation or modulation of other complex pathophysiological processes as therapeutic agents. PMID:27194194

  16. Systemic cancer immunotherapy with Toll-like receptor 7 agonists

    PubMed Central

    Hotz, Christian; Bourquin, Carole

    2012-01-01

    Toll-like receptor (TLR) 7 agonists represent a promising strategy for the immunotherapy of cancer. We have recently investigated the influence of TLR tolerance on the efficacy of systemic tumor treatment with TLR7 ligands. We propose that considering the kinetics of receptor sensitivity highly improves the outcome of cancer immunotherapy. PMID:22720251

  17. Synthesis and immunostimulatory activity of substituted TLR7 agonists.

    PubMed

    Akinbobuyi, Babatope; Wang, Lei; Upchurch, Katherine C; Byrd, Matthew R; Chang, Charles A; Quintana, Jeremy M; Petersen, Rachel E; Seifert, Zacharie J; Boquin, José R; Oh, SangKon; Kane, Robert R

    2016-09-01

    Fifteen new substituted adenines were synthesized as potential TLR7 agonists. These compounds, along with 9 previously reported compounds, were analyzed for TLR7 activity and for the selective stimulation of B cell proliferation. Several functionalized derivatives exhibit significant activity, suggesting their potential for use as vaccine adjuvants. PMID:27476423

  18. The emerging therapeutic roles of κ-opioid agonists.

    PubMed

    Jones, Mark R; Kaye, Alan D; Kaye, Aaron J; Urman, Richard D

    2016-01-01

    The current practice of μ-opioid receptor agonists such as morphine as the primary means of acute and chronic pain relief has several dangerous consequences that limit their effectiveness, including respiratory depression, gastrointestinal motility inhibition, addiction, tolerance, and abuse. Several other opioid receptors, notably the μ-opioid (KOP) receptor, have long been known to play a role in pain relief. Recent discoveries and advancements in laboratory techniques have allowed significant developments of KOP agonists as potential novel therapies for pain relief and other pathological processes. These drugs exhibit none of the classic opioid adverse effects and have displayed pronounced analgesia in several different scenarios. New formulations since 2014 have unveiled increased oral bioavailability, exceptional peripheral versus central selectivity, and a positive safety profile. Continued refinements of established μ-opioid agonist formulations have virtually eliminated the centrally mediated side effects of dysphoria and sedation that limited the applicability of previous KOP agonists. Further research is required to better elucidate the potential of these compounds in pain management, as well as in the mediation or modulation of other complex pathophysiological processes as therapeutic agents.

  19. Synthesis and immunostimulatory activity of substituted TLR7 agonists.

    PubMed

    Akinbobuyi, Babatope; Wang, Lei; Upchurch, Katherine C; Byrd, Matthew R; Chang, Charles A; Quintana, Jeremy M; Petersen, Rachel E; Seifert, Zacharie J; Boquin, José R; Oh, SangKon; Kane, Robert R

    2016-09-01

    Fifteen new substituted adenines were synthesized as potential TLR7 agonists. These compounds, along with 9 previously reported compounds, were analyzed for TLR7 activity and for the selective stimulation of B cell proliferation. Several functionalized derivatives exhibit significant activity, suggesting their potential for use as vaccine adjuvants.

  20. Activation of endplate nicotinic acetylcholine receptors by agonists.

    PubMed

    Auerbach, Anthony

    2015-10-15

    The interaction of a small molecule made in one cell with a large receptor made in another is the signature event of cell signaling. Understanding the structure and energy changes associated with agonist activation is important for engineering drugs, receptors and synapses. The nicotinic acetylcholine receptor (AChR) is a ∼300kD ion channel that binds the neurotransmitter acetylcholine (ACh) and other cholinergic agonists to elicit electrical responses in the central and peripheral nervous systems. This mini-review is in two sections. First, general concepts of skeletal muscle AChR operation are discussed in terms of energy landscapes for conformational change. Second, adult vs. fetal AChRs are compared with regard to interaction energies between ACh and agonist-site side chains, measured by single-channel electrophysiology and molecular dynamics simulations. The five aromatic residues that form the core of each agonist binding site can be divided into two working groups, a triad (led by αY190) that behaves similarly at all sites and a coupled pair (led by γW55) that has a large influence on affinity only in fetal AChRs. Each endplate AChR has 5 homologous subunits, two of α(1) and one each of β, δ, and either γ (fetal) or ϵ (adult). These nicotinic AChRs have only 2 functional agonist binding sites located in the extracellular domain, at αδ and either αγ or αϵ subunit interfaces. The receptor undergoes a reversible, global isomerization between structures called C and O. The C shape does not conduct ions and has a relatively low affinity for ACh, whereas O conducts cations and has a higher affinity. When both agonist sites are empty (filled only with water) the probability of taking on the O conformation (PO) is low, <10(-6). When ACh molecules occupy the agonist sites the C→O opening rate constant and C↔O gating equilibrium constant increase dramatically. Following a pulse of ACh at the nerve-muscle synapse, the endplate current rises rapidly

  1. Sex differences in opioid antinociception: kappa and 'mixed action' agonists.

    PubMed

    Craft, R M; Bernal, S A

    2001-08-01

    A number of investigators have shown that male animals are more sensitive than females to the antinociceptive effects of mu-opioid agonists. The present study was conducted to examine sex differences in opioid antinociception in the rat using agonists known to differ in selectivity for and efficacy at kappa- versus mu-receptors. Dose- and time-effect curves were obtained for s.c. U69593, U50488, ethylketazocine, (-)-bremazocine, (-)-pentazocine, butorphanol and nalbuphine on the 50 or 54 degrees C hotplate and warm water tail withdrawal assays; spontaneous locomotor activity was measured 32-52 min post-injection in the same rats. On the hotplate assay, only butorphanol (54 degrees C) and nalbuphine (50 degrees C) were significantly more potent in males than females. On the tail withdrawal assay, all agonists were significantly more potent or efficacious in males than females at one or both temperatures. In contrast, no agonist was consistently more potent in one sex or the other in decreasing locomotor activity. Estrous stage in female rats only slightly influenced opioid effects, accounting for an average of 2.6% of the variance in females' antinociceptive and locomotor responses to drug (50 degrees C experiment). These results suggest that (1) sex differences in antinociceptive effects of opioids are not mu-receptor-dependent, as they may occur with opioids known to have significant kappa-receptor-mediated activity; (2) the mechanisms underlying sex differences in kappa-opioid antinociception may be primarily spinal rather than supraspinal; (3) sex differences in antinociceptive effects of opioid agonists are not secondary to sex differences in their sedative effects. PMID:11418226

  2. Synthesis and structure-activity relationships of novel indazolyl glucocorticoid receptor partial agonists.

    PubMed

    Gilmore, John L; Sheppeck, James E; Wang, Jim; Dhar, T G Murali; Cavallaro, Cullen; Doweyko, Arthur M; Mckay, Lorraine; Cunningham, Mark D; Habte, Sium F; Nadler, Steven G; Dodd, John H; Somerville, John E; Barrish, Joel C

    2013-10-01

    SAR was used to further develop an indazole class of non-steroidal glucocorticoid receptor agonists aided by a GR LBD (ligand-binding domain)-agonist co-crystal structure described in the accompanying paper. Progress towards discovering a dissociated GR agonist guided by human in vitro assays biased the optimization of this compound series towards partial agonists that possessed excellent selectivity against other nuclear hormone receptors. PMID:23916594

  3. Synthesis and SAR of potent LXR agonists containing an indole pharmacophore

    SciTech Connect

    Washburn, David G.; Hoang, Tram H.; Campobasso, Nino; Smallwood, Angela; Parks, Derek J.; Webb, Christine L.; Frank, Kelly A.; Nord, Melanie; Duraiswami, Chaya; Evans, Christopher; Jaye, Michael; Thompson, Scott K.

    2009-03-27

    A novel series of 1H-indol-1-yl tertiary amine LXR agonists has been designed. Compounds from this series were potent agonists with good rat pharmacokinetic parameters. In addition, the crystal structure of an LXR agonist bound to LXR{alpha} will be disclosed.

  4. Agonists and partial agonists of rhodopsin: retinal polyene methylation affects receptor activation.

    PubMed

    Vogel, Reiner; Lüdeke, Steffen; Siebert, Friedrich; Sakmar, Thomas P; Hirshfeld, Amiram; Sheves, Mordechai

    2006-02-14

    Using Fourier transform infrared (FTIR) difference spectroscopy, we have studied the impact of sites and extent of methylation of the retinal polyene with respect to position and thermodynamic parameters of the conformational equilibrium between the Meta I and Meta II photoproducts of rhodopsin. Deletion of methyl groups to form 9-demethyl and 13-demethyl analogues, as well as addition of a methyl group at C10 or C12, shifted the Meta I/Meta II equilibrium toward Meta I, such that the retinal analogues behaved like partial agonists. This equilibrium shift resulted from an apparent reduction of the entropy gain of the transition of up to 65%, which was only partially offset by a concomitant reduction of the enthalpy increase. The analogues produced Meta II photoproducts with relatively small alterations, while their Meta I states were significantly altered, which accounted for the aberrant transitions to Meta II. Addition of a methyl group at C14 influenced the thermodynamic parameters but had little impact on the position of the Meta I/Meta II equilibrium. Neutralization of the residue 134 in the E134Q opsin mutant increased the Meta II content of the 13-demethyl analogue, but not of the 9-demethyl analogue, indicating a severe impairment of the allosteric coupling between the conserved cytoplasmic ERY motif involved in proton uptake and the Schiff base/Glu 113 microdomain in the 9-demethyl analogue. The 9-methyl group appears therefore essential for the correct positioning of retinal to link protonation of the cytoplasmic motif with protonation of Glu 113 during receptor activation.

  5. Illegal use of beta-adrenergic agonists: European Community.

    PubMed

    Kuiper, H A; Noordam, M Y; van Dooren-Flipsen, M M; Schilt, R; Roos, A H

    1998-01-01

    The use of veterinary medicinal products within the European Community is governed by a series of directives and regulations that describe the requirements for safety, quality, and efficacy of these products. Veterinary therapeutic use of beta-agonists has only been approved in the case of clenbuterol for bronchodilatation in horses and calves and for tocolysis in cows. No beta-agonists have been permitted in the European Community for growth-promoting purposes in farm animals. Surveillance for the presence of residues of veterinary agents in food-producing animals and meat is regulated by the Directive 86/469/EEC containing specific guidelines for sampling procedures on farms and in slaughterhouses. The level and frequency of sampling is dependent on the category of compounds and animal species. When positive samples have been identified (above certain action levels), sampling intensity is increased. Results of monitoring programs in EU member states during 1992 and 1993 for the occurrence of residues of beta-agonists in food-producing animals vary substantially with respect to the percentages of positive samples, ranging from 0 to 7%. The variability is partly explained by differences in sampling strategies, detection methods, and action levels applied. Identification of the proper matrices for sampling and detection of beta-agonists is important. In the case of clenbuterol, hair and choroid retinal tissue are appropriate tissues because clenbuterol accumulates in these matrices. A clear decrease in the use of clenbuterol in cattle has been observed in The Netherlands, Germany, Northern Ireland, and Spanish Basque Country over the last 3 yr. This is partly due to intensified surveillance activities at farms and slaughterhouses by governmental agencies and production sector organizations. There are data on human intoxication following consumption of liver or meat from cattle treated with beta-agonists. At the concentrations of clenbuterol measured in contaminated

  6. Cell type and gene-specific activity of the retinoid inverse agonist AGN 193109: divergent effects from agonist at retinoic acid receptor gamma in human keratinocytes.

    PubMed

    Thacher, S M; Nagpal, S; Klein, E S; Arefieg, T; Krasinski, G; DiSepio, D; Agarwal, C; Johnson, A; Eckert, R L; Chandraratna, R A

    1999-04-01

    Retinoids are important regulators of epithelial differentiation. AGN 193109 is a high-affinity antagonist and inverse agonist for the nuclear retinoic acid receptors (RARs). Paradoxically, both AGN 193109 and retinoid agonists inhibit the expression of the differentiation marker MRP-8 in normal human keratinocytes (NHKs). TTNPB, an RAR agonist, and AGN 193109 mutually antagonize MRP-8 inhibition at both mRNA and protein levels. We find that this antagonism, which is greatest at an AGN 193109:TTNPB ratio of about 10:1, is absent when either compound is in significant excess. The potent RARalpha-specific agonist, AGN 193836, has no effect on MRP-8 regulation. These data indicate that inverse agonists and agonists suppress MRP-8 in NHKs through RARgamma using distinct and mutually inhibitory mechanisms. The activity of AGN 193109 on MRP-8 is cell type specific. In differentiating ECE16-1 cervical cells, TTNPB inhibits while AGN 193109 induces MRP-8 mRNA levels. The effect of AGN 193109 on genes inhibited by retinoid agonists in NHKs is also selective; expression of the differentiation markers transglutaminase 1 and keratin 6 is not down-regulated by AGN 193109 whereas stromelysin-1 expression is suppressed. These results show a complex gene and cell context-specific interplay between agonist and inverse agonist for the regulation of gene expression.

  7. Agonist-antagonist combinations in opioid dependence: a translational approach

    PubMed Central

    Mannelli, P.

    2011-01-01

    Summary The potential therapeutic benefits of co-administering opiate agonist and antagonist agents remain largely to be investigated. This paper focuses on the mechanisms of very low doses of naltrexone that help modulate the effects of methadone withdrawal and review pharmacological properties of the buprenorphine/naltrexone combination that support its clinical investigation. The bench-to-bedside development of the very low dose naltrexone treatment can serve as a translational paradigm to investigate and treat drug addiction. Further research on putative mechanisms elicited by the use of opioid agonist-antagonist combinations may lead to effective pharmacological alternatives to the gold standard methadone treatment, also useful for the management of the abuse of non opioid drugs and alcohol. PMID:22448305

  8. Orvinols with Mixed Kappa/Mu Opioid Receptor Agonist Activity

    PubMed Central

    2013-01-01

    Dual-acting kappa opioid receptor (KOR) agonist and mu opioid receptor (MOR) partial agonist ligands have been put forward as potential treatment agents for cocaine and other psychostimulant abuse. Members of the orvinol series of ligands are known for their high binding affinity to both KOR and MOR, but efficacy at the individual receptors has not been thoroughly evaluated. In this study, it is shown that a predictive model for efficacy at KOR can be derived, with efficacy being controlled by the length of the group attached to C20 and by the introduction of branching into the side chain. In vivo evaluation of two ligands with the desired in vitro profile confirms both display KOR, and to a lesser extent MOR, activity in an analgesic assay suggesting that, in this series, in vitro measures of efficacy using the [35S]GTPγS assay are predictive of the in vivo profile. PMID:23438330

  9. Orvinols with mixed kappa/mu opioid receptor agonist activity.

    PubMed

    Greedy, Benjamin M; Bradbury, Faye; Thomas, Mark P; Grivas, Konstantinos; Cami-Kobeci, Gerta; Archambeau, Ashley; Bosse, Kelly; Clark, Mary J; Aceto, Mario; Lewis, John W; Traynor, John R; Husbands, Stephen M

    2013-04-25

    Dual-acting kappa opioid receptor (KOR) agonist and mu opioid receptor (MOR) partial agonist ligands have been put forward as potential treatment agents for cocaine and other psychostimulant abuse. Members of the orvinol series of ligands are known for their high binding affinity to both KOR and MOR, but efficacy at the individual receptors has not been thoroughly evaluated. In this study, it is shown that a predictive model for efficacy at KOR can be derived, with efficacy being controlled by the length of the group attached to C20 and by the introduction of branching into the side chain. In vivo evaluation of two ligands with the desired in vitro profile confirms both display KOR, and to a lesser extent MOR, activity in an analgesic assay suggesting that, in this series, in vitro measures of efficacy using the [(35)S]GTPγS assay are predictive of the in vivo profile.

  10. Grooming, rank, and agonistic support in tufted capuchin monkeys.

    PubMed

    Schino, Gabriele; Di Giuseppe, Francesca; Visalberghi, Elisabetta

    2009-02-01

    Studies investigating the relation between allogrooming and social rank in capuchin monkeys (genus Cebus) have yielded inconsistent results. In this study, we investigated the relation between grooming, agonistic support, aggression and social rank in a captive group of tufted capuchin monkeys (C. apella). Differently from most previous studies, we based our analyses on a relatively large database and studied a group with known genealogical relationships. Tufted capuchin females did not exchange grooming for rank-related benefits such as agonistic support or reduced aggression. Coherently with this picture, they did not groom up the hierarchy and did not compete for accessing high-ranking grooming partners. It is suggested that a small group size, coupled with a strong kin bias, may make the exchange of grooming for rank-related benefits impossible or unprofitable, thus eliminating the advantages of grooming up the hierarchy. We provide several possible explanations for the heterogeneity of results across capuchin studies that have addressed similar questions.

  11. Ligand Binding Ensembles Determine Graded Agonist Efficacies at a G Protein-coupled Receptor.

    PubMed

    Bock, Andreas; Bermudez, Marcel; Krebs, Fabian; Matera, Carlo; Chirinda, Brian; Sydow, Dominique; Dallanoce, Clelia; Holzgrabe, Ulrike; De Amici, Marco; Lohse, Martin J; Wolber, Gerhard; Mohr, Klaus

    2016-07-29

    G protein-coupled receptors constitute the largest family of membrane receptors and modulate almost every physiological process in humans. Binding of agonists to G protein-coupled receptors induces a shift from inactive to active receptor conformations. Biophysical studies of the dynamic equilibrium of receptors suggest that a portion of receptors can remain in inactive states even in the presence of saturating concentrations of agonist and G protein mimetic. However, the molecular details of agonist-bound inactive receptors are poorly understood. Here we use the model of bitopic orthosteric/allosteric (i.e. dualsteric) agonists for muscarinic M2 receptors to demonstrate the existence and function of such inactive agonist·receptor complexes on a molecular level. Using all-atom molecular dynamics simulations, dynophores (i.e. a combination of static three-dimensional pharmacophores and molecular dynamics-based conformational sampling), ligand design, and receptor mutagenesis, we show that inactive agonist·receptor complexes can result from agonist binding to the allosteric vestibule alone, whereas the dualsteric binding mode produces active receptors. Each agonist forms a distinct ligand binding ensemble, and different agonist efficacies depend on the fraction of purely allosteric (i.e. inactive) versus dualsteric (i.e. active) binding modes. We propose that this concept may explain why agonist·receptor complexes can be inactive and that adopting multiple binding modes may be generalized also to small agonists where binding modes will be only subtly different and confined to only one binding site.

  12. Dopamine Agonists and the Suppression of Impulsive Motor Actions in Parkinson’s Disease

    PubMed Central

    Wylie, S.A.; Claassen, D.O.; Huizenga, H.M.; Schewel, K.D.; Ridderinkhof, K.R.; Bashore, T.R.; van den Wildenberg, W.P.M.

    2012-01-01

    The suppression of spontaneous motor impulses is an essential facet of cognitive control that is linked to frontal-basal ganglia circuitry. Basal ganglia dysfunction caused by Parkinson’s disease (PD) disrupts the proficiency of action suppression, but how pharmacotherapy for PD impacts impulsive motor control is poorly understood. Dopamine agonists improve motor symptoms of PD, but can also provoke impulsive-compulsive behaviors (ICB). We investigated whether dopamine agonist medication has a beneficial or detrimental effect on impulsive action control in thirty-eight PD patients, half of whom had current ICB. Participants performed the Simon conflict task, which measures susceptibility to acting on spontaneous action impulses as well as the proficiency of suppressing these impulses. Compared to an off agonist state, patients on their agonist were no more susceptible to reacting impulsively, but were less proficient at suppressing the interference from the activation of impulsive actions. Importantly, agonist effects depended on baseline performance in the off agonist state; more proficient suppressors off agonist experienced a reduction in suppression on agonist, whereas less proficient suppressors off agonist showed improved suppression on agonist. Patients with active ICB were actually less susceptible to making fast, impulsive response errors than patients without ICB, suggesting that behavioral problems in this subset of patients may be less related to impulsivity in motor control. Our findings provide further evidence that dopamine agonist medication impacts specific cognitive control processes and that the direction of its effects depends on individual differences in performance off medication. PMID:22571461

  13. Ligand Binding Ensembles Determine Graded Agonist Efficacies at a G Protein-coupled Receptor.

    PubMed

    Bock, Andreas; Bermudez, Marcel; Krebs, Fabian; Matera, Carlo; Chirinda, Brian; Sydow, Dominique; Dallanoce, Clelia; Holzgrabe, Ulrike; De Amici, Marco; Lohse, Martin J; Wolber, Gerhard; Mohr, Klaus

    2016-07-29

    G protein-coupled receptors constitute the largest family of membrane receptors and modulate almost every physiological process in humans. Binding of agonists to G protein-coupled receptors induces a shift from inactive to active receptor conformations. Biophysical studies of the dynamic equilibrium of receptors suggest that a portion of receptors can remain in inactive states even in the presence of saturating concentrations of agonist and G protein mimetic. However, the molecular details of agonist-bound inactive receptors are poorly understood. Here we use the model of bitopic orthosteric/allosteric (i.e. dualsteric) agonists for muscarinic M2 receptors to demonstrate the existence and function of such inactive agonist·receptor complexes on a molecular level. Using all-atom molecular dynamics simulations, dynophores (i.e. a combination of static three-dimensional pharmacophores and molecular dynamics-based conformational sampling), ligand design, and receptor mutagenesis, we show that inactive agonist·receptor complexes can result from agonist binding to the allosteric vestibule alone, whereas the dualsteric binding mode produces active receptors. Each agonist forms a distinct ligand binding ensemble, and different agonist efficacies depend on the fraction of purely allosteric (i.e. inactive) versus dualsteric (i.e. active) binding modes. We propose that this concept may explain why agonist·receptor complexes can be inactive and that adopting multiple binding modes may be generalized also to small agonists where binding modes will be only subtly different and confined to only one binding site. PMID:27298318

  14. Mixed Kappa/Mu Opioid Receptor Agonists: The 6β-Naltrexamines

    PubMed Central

    Cami-Kobeci, Gerta; Neal, Adrian P.; Bradbury, Faye A.; Purington, Lauren C.; Aceto, Mario D.; Harris, Louis S.; Lewis, John W.; Traynor, John R.; Husbands, Stephen M.

    2011-01-01

    Ligands from the naltrexamine series have consistently demonstrated agonist activity at kappa opioid receptors (KOR), with varying activity at the mu opioid receptor (MOR). Various 6β-cinnamoylamino derivatives were made with the aim of generating ligands with a KOR agonist/MOR partial agonist profile, as ligands with this activity may be of interest as treatment agents for cocaine abuse. The ligands all displayed the desired high affinity, non-selective binding in vitro and in the functional assays were high efficacy KOR agonists with some partial agonist activity at MOR. Two of the new ligands (12a, 12b) have been evaluated in vivo, with 12a acting as a KOR agonist, and therefore somewhat similar to the previously evaluated analogues 3–6, while 12b displayed predominant MOR agonist activity. PMID:19253970

  15. Octopaminergic agonists for the cockroach neuronal octopamine receptor

    PubMed Central

    Hirashima, Akinori; Morimoto, Masako; Kuwano, Eiichi; Eto, Morifusa

    2003-01-01

    The compounds 1-(2,6-diethylphenyl)imidazolidine-2-thione and 2-(2,6-diethylphenyl)imidazolidine showed the almost same activity as octopamine in stimulating adenylate cyclase of cockroach thoracic nervous system among 70 octopamine agonists, suggesting that only these compounds are full octopamine agonists and other compounds are partial octopamine agonists. The quantitative structure-activity relationship of a set of 22 octopamine agonists against receptor 2 in cockroach nervous tissue, was analyzed using receptor surface modeling. Three-dimensional energetics descriptors were calculated from receptor surface model/ligand interaction and these three-dimensional descriptors were used in quantitative structure-activity relationship analysis. A receptor surface model was generated using some subset of the most active structures and the results provided useful information in the characterization and differentiation of octopaminergic receptor. Abbreviation: AEA arylethanolamine AII 2-(arylimino)imidazolidine AIO 2-(arylimino)oxazolidine AIT 2-(arylimino)thiazolidine APAT 2-(α-phenylethylamino)-2-thiazoline BPAT 2-(β-phenylethylamino)-2-thiazoline CAO 2-(3-chlorobenzylamino)-2-oxazoline DCAO 2-(3,5-dichlorobenzylamino)-2-oxazoline DET5 2-(2,6-diethylphenylimino)-5-methylthiazolidine DET6 2-(2,6-diethylphenylimino)thiazine EGTA ethylene glycol bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid GFA genetic function approximation G/PLS genetic partial least squares IND 2-aminomethyl-2-indanol LAH lithium aluminum hydride MCSG maximum common subgroup MCT6 2-(2-methyl-4-chlorophenylimino)thiazine OA octopamine PLS partial least squares QSAR quantitative structure-activity relationship SBAT 2-(substituted benzylamino)-2-thiazoline SD the sum of squared deviations of the dependent variable values from their mean SPIT 3-(substituted phenyl)imidazolidine-2-thione THI 2-amino-1-(2-thiazoyl)ethanol TMS tetramethyl silane PMID:15841226

  16. Newspapers and newspaper ink contain agonists for the ah receptor.

    PubMed

    Bohonowych, Jessica E S; Zhao, Bin; Timme-Laragy, Alicia; Jung, Dawoon; Di Giulio, Richard T; Denison, Michael S

    2008-04-01

    Ligand-dependent activation of the aryl hydrocarbon receptor (AhR) pathway leads to a diverse array of biological and toxicological effects. The best-studied ligands for the AhR include polycyclic and halogenated aromatic hydrocarbons, the most potent of which is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). However, as new AhR ligands are identified and characterized, their structural and physiochemical diversity continues to expand. Our identification of AhR agonists in crude extracts from diverse materials raises questions as to the magnitude and extent of human exposure to AhR ligands through normal daily activities. We have found that solvent extracts of newspapers from countries around the world stimulate the AhR signaling pathway. AhR agonist activity was observed for dimethyl sulfoxide (DMSO), ethanol, and water extracts of printed newspaper, unprinted virgin paper, and black printing ink, where activation of luciferase reporter gene expression was transient, suggesting that the AhR active chemical(s) was metabolically labile. DMSO and ethanol extracts also stimulated AhR transformation and DNA binding, and also competed with [(3)H]TCDD for binding to the AhR. In addition, DMSO extracts of printed newspaper induced cytochrome P450 1A associated 7-ethoxyresorufin-O-deethylase activity in zebrafish embryos in vivo. Although the responsible bioactive chemical(s) remain to be identified, our results demonstrate that newspapers and printing ink contain relatively potent metabolically labile agonists of the AhR. Given the large amount of recycling and reprocessing of newspapers throughout the world, release of these easily extractable AhR agonists into the environment should be examined and their potential effects on aquatic organisms assessed. PMID:18203687

  17. Synthesis of fluorinated agonist of sphingosine-1-phosphate receptor 1.

    PubMed

    Aliouane, Lucie; Chao, Sovy; Brizuela, Leyre; Pfund, Emmanuel; Cuvillier, Olivier; Jean, Ludovic; Renard, Pierre-Yves; Lequeux, Thierry

    2014-09-01

    The bioactive metabolite sphingosine-1-phosphate (S1P), a product of sphingosine kinases (SphKs), mediates diverse biological processes such as cell differentiation, proliferation, survival and angiogenesis. A fluorinated analogue of S1P receptor agonist has been synthesized by utilizing a ring opening reaction of oxacycles by a lithiated difluoromethylphosphonate anion as the key reaction. In vitro activity of this S1P analogue is also reported.

  18. A human platelet calcium calculator trained by pairwise agonist scanning.

    PubMed

    Lee, Mei Yan; Diamond, Scott L

    2015-02-01

    Since platelet intracellular calcium mobilization [Ca(t)]i controls granule release, cyclooxygenase-1 and integrin activation, and phosphatidylserine exposure, blood clotting simulations require prediction of platelet [Ca(t)]i in response to combinatorial agonists. Pairwise Agonist Scanning (PAS) deployed all single and pairwise combinations of six agonists (ADP, convulxin, thrombin, U46619, iloprost and GSNO used at 0.1, 1, and 10xEC50; 154 conditions including a null condition) to stimulate platelet P2Y1/P2Y12 GPVI, PAR1/PAR4, TP, IP receptors, and guanylate cyclase, respectively, in Factor Xa-inhibited (250 nM apixaban), diluted platelet rich plasma that had been loaded with the calcium dye Fluo-4 NW. PAS of 10 healthy donors provided [Ca(t)]i data for training 10 neural networks (NN, 2-layer/12-nodes) per donor. Trinary stimulations were then conducted at all 0.1x and 1xEC50 doses (160 conditions) as was a sampling of 45 higher ordered combinations (four to six agonists). The NN-ensemble average was a calcium calculator that accurately predicted [Ca (t)]i beyond the single and binary training set for trinary stimulations (R = 0.924). The 160 trinary synergy scores, a normalized metric of signaling crosstalk, were also well predicted (R = 0.850) as were the calcium dynamics (R = 0.871) and high-dimensional synergy scores (R = 0.695) for the 45 higher ordered conditions. The calculator even predicted sequential addition experiments (n = 54 conditions, R = 0.921). NN-ensemble is a fast calcium calculator, ideal for multiscale clotting simulations that include spatiotemporal concentrations of ADP, collagen, thrombin, thromboxane, prostacyclin, and nitric oxide.

  19. Alpha-adrenoceptor agonistic activity of oxymetazoline and xylometazoline.

    PubMed

    Haenisch, Britta; Walstab, Jutta; Herberhold, Stephan; Bootz, Friedrich; Tschaikin, Marion; Ramseger, René; Bönisch, Heinz

    2010-12-01

    Oxymetazoline and xylometazoline are both used as nasal mucosa decongesting α-adrenoceptor agonists during a common cold. However, it is largely unknown which of the six α-adrenoceptor subtypes are actually present in human nasal mucosa, which are activated by the two alpha-adrenoceptor agonists and to what extent. Therefore, mRNA expression in human nasal mucosa of the six α-adrenoceptor subtypes was studied. Furthermore, the affinity and potency of the imidazolines oxymetazoline and xylometazoline at these α-adrenoceptor subtypes were examined in transfected HEK293 cells. The rank order of mRNA levels of α-adrenoceptor subtypes in human nasal mucosa was: α(2A) > α(1A) ≥ α(2B) > α(1D) ≥ α(2C) > α(1B) . Oxymetazoline and xylometazoline exhibited in radioligand competition studies higher affinities than the catecholamines adrenaline and noradrenaline at most α-adrenoceptor subtypes. Compared to xylometazoline, oxymetazoline exhibited a significantly higher affinity at α(1A) - but a lower affinity at α(2B) -adrenoceptors. In functional studies in which adrenoceptor-mediated Ca(2+) signals were measured, both, oxymetazoline and xylometazoline behaved at α(2B) -adrenoceptors as full agonists but oxymetazoline was significantly more potent than xylometazoline. Furthermore, oxymetazoline was also a partial agonist at α(1A) -adrenoceptors; however, its potency was relatively low and it was much lower than its affinity. The higher potency at α(2B) -adrenoceptors, i.e. at receptors highly expressed at the mRNA level in human nasal mucosa, could eventually explain why in nasal decongestants oxymetazoline can be used in lower concentrations than xylometazoline.

  20. Alpha-adrenoceptor agonistic activity of oxymetazoline and xylometazoline.

    PubMed

    Haenisch, Britta; Walstab, Jutta; Herberhold, Stephan; Bootz, Friedrich; Tschaikin, Marion; Ramseger, René; Bönisch, Heinz

    2010-12-01

    Oxymetazoline and xylometazoline are both used as nasal mucosa decongesting α-adrenoceptor agonists during a common cold. However, it is largely unknown which of the six α-adrenoceptor subtypes are actually present in human nasal mucosa, which are activated by the two alpha-adrenoceptor agonists and to what extent. Therefore, mRNA expression in human nasal mucosa of the six α-adrenoceptor subtypes was studied. Furthermore, the affinity and potency of the imidazolines oxymetazoline and xylometazoline at these α-adrenoceptor subtypes were examined in transfected HEK293 cells. The rank order of mRNA levels of α-adrenoceptor subtypes in human nasal mucosa was: α(2A) > α(1A) ≥ α(2B) > α(1D) ≥ α(2C) > α(1B) . Oxymetazoline and xylometazoline exhibited in radioligand competition studies higher affinities than the catecholamines adrenaline and noradrenaline at most α-adrenoceptor subtypes. Compared to xylometazoline, oxymetazoline exhibited a significantly higher affinity at α(1A) - but a lower affinity at α(2B) -adrenoceptors. In functional studies in which adrenoceptor-mediated Ca(2+) signals were measured, both, oxymetazoline and xylometazoline behaved at α(2B) -adrenoceptors as full agonists but oxymetazoline was significantly more potent than xylometazoline. Furthermore, oxymetazoline was also a partial agonist at α(1A) -adrenoceptors; however, its potency was relatively low and it was much lower than its affinity. The higher potency at α(2B) -adrenoceptors, i.e. at receptors highly expressed at the mRNA level in human nasal mucosa, could eventually explain why in nasal decongestants oxymetazoline can be used in lower concentrations than xylometazoline. PMID:20030735

  1. Antipsychotic Induced Symptomatic Hyperprolactinemia: Are Dopamine Agonists Safe?

    PubMed Central

    Lertxundi, Unax; Domingo-Echaburu, Saioa; Peral, Javier; García, Montserrat

    2011-01-01

    Published literature shows that dopamine agonists can reverse antipsychotic-induced hyperprolactinemia without worsening psychotic symptoms in the majority of schizophrenic patients. However, psychiatrists have been reluctant to use drugs with dopaminergic properties for fear of exacerbating psychiatric symptoms. There are reported cases of psychosis worsening published for both cabergoline and bromocriptine. Cabergoline has proven to be more effective and safe when used to treat hyperprolactinemia, but whether cabergoline is also safer than bromocriptine in antipsychotic induced hyperprolactinemia remains unproven.

  2. A human platelet calcium calculator trained by pairwise agonist scanning.

    PubMed

    Lee, Mei Yan; Diamond, Scott L

    2015-02-01

    Since platelet intracellular calcium mobilization [Ca(t)]i controls granule release, cyclooxygenase-1 and integrin activation, and phosphatidylserine exposure, blood clotting simulations require prediction of platelet [Ca(t)]i in response to combinatorial agonists. Pairwise Agonist Scanning (PAS) deployed all single and pairwise combinations of six agonists (ADP, convulxin, thrombin, U46619, iloprost and GSNO used at 0.1, 1, and 10xEC50; 154 conditions including a null condition) to stimulate platelet P2Y1/P2Y12 GPVI, PAR1/PAR4, TP, IP receptors, and guanylate cyclase, respectively, in Factor Xa-inhibited (250 nM apixaban), diluted platelet rich plasma that had been loaded with the calcium dye Fluo-4 NW. PAS of 10 healthy donors provided [Ca(t)]i data for training 10 neural networks (NN, 2-layer/12-nodes) per donor. Trinary stimulations were then conducted at all 0.1x and 1xEC50 doses (160 conditions) as was a sampling of 45 higher ordered combinations (four to six agonists). The NN-ensemble average was a calcium calculator that accurately predicted [Ca (t)]i beyond the single and binary training set for trinary stimulations (R = 0.924). The 160 trinary synergy scores, a normalized metric of signaling crosstalk, were also well predicted (R = 0.850) as were the calcium dynamics (R = 0.871) and high-dimensional synergy scores (R = 0.695) for the 45 higher ordered conditions. The calculator even predicted sequential addition experiments (n = 54 conditions, R = 0.921). NN-ensemble is a fast calcium calculator, ideal for multiscale clotting simulations that include spatiotemporal concentrations of ADP, collagen, thrombin, thromboxane, prostacyclin, and nitric oxide. PMID:25723389

  3. Improving the developability profile of pyrrolidine progesterone receptor partial agonists

    SciTech Connect

    Kallander, Lara S.; Washburn, David G.; Hoang, Tram H.; Frazee, James S.; Stoy, Patrick; Johnson, Latisha; Lu, Qing; Hammond, Marlys; Barton, Linda S.; Patterson, Jaclyn R.; Azzarano, Leonard M.; Nagilla, Rakesh; Madauss, Kevin P.; Williams, Shawn P.; Stewart, Eugene L.; Duraiswami, Chaya; Grygielko, Eugene T.; Xu, Xiaoping; Laping, Nicholas J.; Bray, Jeffrey D.; Thompson, Scott K.

    2010-09-17

    The previously reported pyrrolidine class of progesterone receptor partial agonists demonstrated excellent potency but suffered from serious liabilities including hERG blockade and high volume of distribution in the rat. The basic pyrrolidine amine was intentionally converted to a sulfonamide, carbamate, or amide to address these liabilities. The evaluation of the degree of partial agonism for these non-basic pyrrolidine derivatives and demonstration of their efficacy in an in vivo model of endometriosis is disclosed herein.

  4. A Human Platelet Calcium Calculator Trained by Pairwise Agonist Scanning

    PubMed Central

    Lee, Mei Yan; Diamond, Scott L.

    2015-01-01

    Since platelet intracellular calcium mobilization [Ca(t)]i controls granule release, cyclooxygenase-1 and integrin activation, and phosphatidylserine exposure, blood clotting simulations require prediction of platelet [Ca(t)]i in response to combinatorial agonists. Pairwise Agonist Scanning (PAS) deployed all single and pairwise combinations of six agonists (ADP, convulxin, thrombin, U46619, iloprost and GSNO used at 0.1, 1, and 10xEC50; 154 conditions including a null condition) to stimulate platelet P2Y1/P2Y12 GPVI, PAR1/PAR4, TP, IP receptors, and guanylate cyclase, respectively, in Factor Xa-inhibited (250 nM apixaban), diluted platelet rich plasma that had been loaded with the calcium dye Fluo-4 NW. PAS of 10 healthy donors provided [Ca(t)]i data for training 10 neural networks (NN, 2-layer/12-nodes) per donor. Trinary stimulations were then conducted at all 0.1x and 1xEC50 doses (160 conditions) as was a sampling of 45 higher ordered combinations (four to six agonists). The NN-ensemble average was a calcium calculator that accurately predicted [Ca (t)]i beyond the single and binary training set for trinary stimulations (R = 0.924). The 160 trinary synergy scores, a normalized metric of signaling crosstalk, were also well predicted (R = 0.850) as were the calcium dynamics (R = 0.871) and high-dimensional synergy scores (R = 0.695) for the 45 higher ordered conditions. The calculator even predicted sequential addition experiments (n = 54 conditions, R = 0.921). NN-ensemble is a fast calcium calculator, ideal for multiscale clotting simulations that include spatiotemporal concentrations of ADP, collagen, thrombin, thromboxane, prostacyclin, and nitric oxide. PMID:25723389

  5. Gonadotropin-releasing hormone agonist-induced pituitary apoplexy

    PubMed Central

    Keane, Fergus; Navin, Patrick; Brett, Francesca; Dennedy, Michael C

    2016-01-01

    Summary Pituitary apoplexy represents an uncommon endocrine emergency with potentially life-threatening consequences. Drug-induced pituitary apoplexy is a rare but important consideration when evaluating patients with this presentation. We describe an unusual case of a patient with a known pituitary macroadenoma presenting with acute-onset third nerve palsy and headache secondary to tumour enlargement and apoplexy. This followed gonadotropin-releasing hormone (GNRH) agonist therapy used to treat metastatic prostate carcinoma. Following acute management, the patient underwent transphenoidal debulking of his pituitary gland with resolution of his third nerve palsy. Subsequent retrospective data interpretation revealed that this had been a secretory gonadotropinoma and GNRH agonist therapy resulted in raised gonadotropins and testosterone. Hence, further management of his prostate carcinoma required GNRH antagonist therapy and external beam radiotherapy. This case demonstrates an uncommon complication of GNRH agonist therapy in the setting of a pituitary macroadenoma. It also highlights the importance of careful, serial data interpretation in patients with pituitary adenomas. Finally, this case presents a unique insight into the challenges of managing a hormonal-dependent prostate cancer in a patient with a secretory pituitary tumour. Learning points While non-functioning gonadotropinomas represent the most common form of pituitary macroadenoma, functioning gonadotropinomas are exceedingly rare. Acute tumour enlargement, with potential pituitary apoplexy, is a rare but important adverse effect arising from GNRH agonist therapy in the presence of both functioning and non-functioning pituitary gonadotropinomas. GNRH antagonist therapy represents an alternative treatment option for patients with hormonal therapy-requiring prostate cancer, who also have diagnosed with a pituitary gonadotropinoma. PMID:27284452

  6. Testosterone and farnesoid X receptor agonist INT-747 counteract high fat diet-induced bladder alterations in a rabbit model of metabolic syndrome.

    PubMed

    Morelli, Annamaria; Comeglio, Paolo; Filippi, Sandra; Sarchielli, Erica; Cellai, Ilaria; Vignozzi, Linda; Yehiely-Cohen, Ravit; Maneschi, Elena; Gacci, Mauro; Carini, Marco; Adorini, Luciano; Vannelli, Gabriella B; Maggi, Mario

    2012-10-01

    In the male, metabolic syndrome (MetS) is associated to an increased risk of benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTS). A recently established rabbit model of high fat diet (HFD)-induced MetS showed hypogonadism and the presence of prostate gland alterations, including inflammation, hypoxia and fibrosis. The present study investigated whether HFD-induced MetS might also alter bladder structure and function. Testosterone and the farnesoid X receptor (FXR) agonist INT-747, were evaluated for possible effects on HFD bladder. MetS rabbits develop bladder alterations, including fibrosis (reduced muscle/fiber ratio), hypoxia [2-fold increase as compared to regular diet (RD) group], low-grade inflammation (increased leukocyte infiltration and inflammatory markers) and RhoA/ROCK hyperactivity. Bladder strips from HFD rabbits, pre-contracted with carbachol, showed an overactive response to the selective ROCK inhibitor Y-27632. All these HFD-induced bladder alterations were partially blunted by testosterone and almost completely reverted by INT-747. Both treatments prevented some MetS features (glucose intolerance and visceral fat increase), thus suggesting that their effects on bladder could be ascribed to an improvement of the metabolic and/or hypogonadal state. However, a pathogenetic role for hypogonadism has been ruled out as GnRH analog-induced hypogonadal rabbits, fed a regular diet, did not show any detectable bladder alterations. In addition, INT-747 did not revert the MetS-induced hypogonadal state. FXR mRNA was highly expressed in rabbit bladder and positively associated with visceral fat increase. A direct effect of INT-747 on bladder smooth muscle was further suggested by inhibition of RhoA/ROCK-mediated activity by in vitro experiments on isolated cells. In conclusion, HFD-related MetS features are associated to bladder derangements, which are ameliorated by testosterone or INT-747 administration. INT-747 showed the most marked

  7. Increased flow precedes remote arteriolar dilations for some microapplied agonists.

    PubMed

    Frame, M D

    2000-04-01

    This study asks which occurs first in time for remote responses: a dilation or a remote change in flow. Arteriolar diameter (approximately 20 microm) and fluorescently labeled red blood cell (RBC) velocity were measured in the cremaster muscle of anesthetized (pentobarbital sodium, 70 mg/kg) hamsters (n = 51). Arterioles were locally stimulated for 60 s with micropipette-applied 10 microg/ml LM-609 (alpha(v)beta(3)-integrin agonist), 10(-3) M adenosine, or 10(-3) M 3-morpholinosydnonimine (SIN-1, nitric oxide donor) as remote response agonists or with 10(-3) M papaverine, which dilates only locally. Observations were made at a remote site 1,200 microm upstream. With LM-609 or adenosine, the RBC velocity increased first (within 5 s), and the remote dilation followed 5-7 s later. N-nitro-L-arginine (100 microM) blocked the LM-609 (100%) and adenosine (60%) remote dilations. SIN-1 induced a concurrent remote dilation and decrease in RBC velocity (approximately 10 s), suggesting the primary signal was to dilate. Papaverine had no remote effects. This study suggests that, although remote responses to some agonists are induced by primary signals to dilate, additionally, network changes in flow can stimulate extensive remote changes in diameter.

  8. Suppression of atherosclerosis by synthetic REV-ERB agonist

    SciTech Connect

    Sitaula, Sadichha; Billon, Cyrielle; Kamenecka, Theodore M.; Solt, Laura A.; Burris, Thomas P.

    2015-05-08

    The nuclear receptors for heme, REV-ERBα and REV-ERBβ, play important roles in the regulation of metabolism and inflammation. Recently it was demonstrated that reduced REV-ERBα expression in hematopoetic cells in LDL receptor null mice led to increased atherosclerosis. We sought to determine if synthetic REV-ERB agonists that we have developed might have the ability to suppress atherosclerosis in this model. A previously characterized synthetic REV-ERB agonist, SR9009, was used to determine if activation of REV-ERB activity would affect atherosclerosis in LDL receptor deficient mice. Atherosclerotic plaque size was significantly reduced (p < 0.05) in mice administered SR9009 (100 mg/kg) for seven weeks compared to control mice (n = 10 per group). SR9009 treatment of bone marrow-derived mouse macrophages (BMDM) reduced the polarization of BMDMs to proinflammatory M1 macrophage while increasing the polarization of BMDMs to anti-inflammatory M2 macrophages. Our results suggest that pharmacological targeting of REV-ERBs may be a viable therapeutic option for treatment of atherosclerosis. - Highlights: • Synthetic REV-ERB agonist treatment reduced atherosclerosis in a mouse model. • Pharmacological activation of REV-ERB decreased M1 macrophage polarization. • Pharmacological activation of REV-ERB increased M2 macrophage polarization.

  9. Emerging strategies for exploiting cannabinoid receptor agonists as medicines.

    PubMed

    Pertwee, Roger G

    2009-02-01

    Medicines that activate cannabinoid CB(1) and CB(2) receptor are already in the clinic. These are Cesamet (nabilone), Marinol (dronabinol; Delta(9)-tetrahydrocannabinol) and Sativex (Delta(9)-tetrahydrocannabinol with cannabidiol). The first two of these medicines can be prescribed to reduce chemotherapy-induced nausea and vomiting. Marinol can also be prescribed to stimulate appetite, while Sativex is prescribed for the symptomatic relief of neuropathic pain in adults with multiple sclerosis and as an adjunctive analgesic treatment for adult patients with advanced cancer. One challenge now is to identify additional therapeutic targets for cannabinoid receptor agonists, and a number of potential clinical applications for such agonists are mentioned in this review. A second challenge is to develop strategies that will improve the efficacy and/or the benefit-to-risk ratio of a cannabinoid receptor agonist. This review focuses on five strategies that have the potential to meet either or both of these objectives. These are strategies that involve: (i) targeting cannabinoid receptors located outside the blood-brain barrier; (ii) targeting cannabinoid receptors expressed by a particular tissue; (iii) targeting up-regulated cannabinoid receptors; (iv) targeting cannabinoid CB(2) receptors; or (v) 'multi-targeting'. Preclinical data that justify additional research directed at evaluating the clinical importance of each of these strategies are also discussed. PMID:19226257

  10. Molecular impact of juvenile hormone agonists on neonatal Daphnia magna.

    PubMed

    Toyota, Kenji; Kato, Yasuhiko; Miyakawa, Hitoshi; Yatsu, Ryohei; Mizutani, Takeshi; Ogino, Yukiko; Miyagawa, Shinichi; Watanabe, Hajime; Nishide, Hiroyo; Uchiyama, Ikuo; Tatarazako, Norihisa; Iguchi, Taisen

    2014-05-01

    Daphnia magna has been used extensively to evaluate organism- and population-level responses to pollutants in acute toxicity and reproductive toxicity tests. We have previously reported that exposure to juvenile hormone (JH) agonists results in a reduction of reproductive function and production of male offspring in a cyclic parthenogenesis, D. magna. Recent advances in molecular techniques have provided tools to understand better the responses to pollutants in aquatic organisms, including D. magna. DNA microarray was used to evaluate gene expression profiles of neonatal daphnids exposed to JH agonists: methoprene (125, 250 and 500 ppb), fenoxycarb (0.5, 1 and 2 ppb) and epofenonane (50, 100 and 200 ppb). Exposure to these JH analogs resulted in chemical-specific patterns of gene expression. The heat map analyses based on hierarchical clustering revealed a similar pattern between treatments with a high dose of methoprene and with epofenonane. In contrast, treatment with low to middle doses of methoprene resulted in similar profiles to fenoxycarb treatments. Hemoglobin and JH epoxide hydrolase genes were clustered as JH-responsive genes. These data suggest that fenoxycarb has high activity as a JH agonist, methoprene shows high toxicity and epofenonane works through a different mechanism compared with other JH analogs, agreeing with data of previously reported toxicity tests. In conclusion, D. magna DNA microarray is useful for the classification of JH analogs and identification of JH-responsive genes. PMID:24038158

  11. Structure of the agonist-bound neurotensin receptor.

    PubMed

    White, Jim F; Noinaj, Nicholas; Shibata, Yoko; Love, James; Kloss, Brian; Xu, Feng; Gvozdenovic-Jeremic, Jelena; Shah, Priyanka; Shiloach, Joseph; Tate, Christopher G; Grisshammer, Reinhard

    2012-10-25

    Neurotensin (NTS) is a 13-amino-acid peptide that functions as both a neurotransmitter and a hormone through the activation of the neurotensin receptor NTSR1, a G-protein-coupled receptor (GPCR). In the brain, NTS modulates the activity of dopaminergic systems, opioid-independent analgesia, and the inhibition of food intake; in the gut, NTS regulates a range of digestive processes. Here we present the structure at 2.8 Å resolution of Rattus norvegicus NTSR1 in an active-like state, bound to NTS(8-13), the carboxy-terminal portion of NTS responsible for agonist-induced activation of the receptor. The peptide agonist binds to NTSR1 in an extended conformation nearly perpendicular to the membrane plane, with the C terminus oriented towards the receptor core. Our findings provide, to our knowledge, the first insight into the binding mode of a peptide agonist to a GPCR and may support the development of non-peptide ligands that could be useful in the treatment of neurological disorders, cancer and obesity.

  12. Molecular impact of juvenile hormone agonists on neonatal Daphnia magna.

    PubMed

    Toyota, Kenji; Kato, Yasuhiko; Miyakawa, Hitoshi; Yatsu, Ryohei; Mizutani, Takeshi; Ogino, Yukiko; Miyagawa, Shinichi; Watanabe, Hajime; Nishide, Hiroyo; Uchiyama, Ikuo; Tatarazako, Norihisa; Iguchi, Taisen

    2014-05-01

    Daphnia magna has been used extensively to evaluate organism- and population-level responses to pollutants in acute toxicity and reproductive toxicity tests. We have previously reported that exposure to juvenile hormone (JH) agonists results in a reduction of reproductive function and production of male offspring in a cyclic parthenogenesis, D. magna. Recent advances in molecular techniques have provided tools to understand better the responses to pollutants in aquatic organisms, including D. magna. DNA microarray was used to evaluate gene expression profiles of neonatal daphnids exposed to JH agonists: methoprene (125, 250 and 500 ppb), fenoxycarb (0.5, 1 and 2 ppb) and epofenonane (50, 100 and 200 ppb). Exposure to these JH analogs resulted in chemical-specific patterns of gene expression. The heat map analyses based on hierarchical clustering revealed a similar pattern between treatments with a high dose of methoprene and with epofenonane. In contrast, treatment with low to middle doses of methoprene resulted in similar profiles to fenoxycarb treatments. Hemoglobin and JH epoxide hydrolase genes were clustered as JH-responsive genes. These data suggest that fenoxycarb has high activity as a JH agonist, methoprene shows high toxicity and epofenonane works through a different mechanism compared with other JH analogs, agreeing with data of previously reported toxicity tests. In conclusion, D. magna DNA microarray is useful for the classification of JH analogs and identification of JH-responsive genes.

  13. Meclizine is an agonist ligand for mouse constitutive androstane receptor (CAR) and an inverse agonist for human CAR.

    PubMed

    Huang, Wendong; Zhang, Jun; Wei, Ping; Schrader, William T; Moore, David D

    2004-10-01

    The constitutive androstane receptor (CAR, NR1I3) is a key regulator of xenobiotic and endobiotic metabolism. The ligand-binding domains of murine (m) and human (h) CAR are divergent relative to other nuclear hormone receptors, resulting in species-specific differences in xenobiotic responses. Here we identify the widely used antiemetic meclizine (Antivert; Bonine) as both an agonist ligand for mCAR and an inverse agonist for hCAR. Meclizine increases mCAR transactivation in a dose-dependent manner. Like the mCAR agonist 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene, meclizine stimulates binding of steroid receptor coactivator 1 to the murine receptor in vitro. Meclizine administration to mice increases expression of CAR target genes in a CAR-dependent manner. In contrast, meclizine suppresses hCAR transactivation and inhibits the phenobarbital-induced expression of the CAR target genes, cytochrome p450 monooxygenase (CYP)2B10, CYP3A11, and CYP1A2, in primary hepatocytes derived from mice expressing hCAR, but not mCAR. The inhibitory effect of meclizine also suppresses acetaminophen-induced liver toxicity in humanized CAR mice. These results demonstrate that a single compound can induce opposite xenobiotic responses via orthologous receptors in rodents and humans. PMID:15272053

  14. Additive antinociceptive effects of mixtures of the κ-opioid receptor agonist spiradoline and the cannabinoid receptor agonist CP55940 in rats.

    PubMed

    Maguire, David R; France, Charles P

    2016-02-01

    Pain is a significant clinical problem, and there is a need for pharmacotherapies that are more effective with fewer adverse effects than currently available medications. Cannabinoid receptor agonists enhance the antinociceptive effects of μ-opioid receptor agonists; it is unclear whether they impact the effects of agonists acting at other opioid receptors. κ-Opioid receptor agonists have antinociceptive effects, but their clinical use is precluded by adverse effects; however, their therapeutic potential might be realized if antinociceptive effects could be selectively enhanced. In this study, the antinociceptive effects of the cannabinoid receptor agonist CP55940 and the κ-opioid receptor agonist spiradoline, alone and in combination, were studied in rats (n=7) using a warm water tail-withdrawal procedure. When administered alone, CP55940 (0.032-1.0 mg/kg) and spiradoline (1.0-32.0 mg/kg) increased tail-withdrawal latency, and mixtures of CP55940 and spiradoline (ratios of 1 : 3, 1 : 1, and 3 : 1) produced additive effects. It remains to be determined whether this additive interaction between a κ-opioid receptor agonist and a cannabinoid receptor agonist is selective for antinociception and whether it can be generalized to other drugs. PMID:26292184

  15. Different serotonin receptor agonists have distinct effects on sound-evoked responses in inferior colliculus.

    PubMed

    Hurley, Laura M

    2006-11-01

    The neuromodulator serotonin has a complex set of effects on the auditory responses of neurons within the inferior colliculus (IC), a midbrain auditory nucleus that integrates a wide range of inputs from auditory and nonauditory sources. To determine whether activation of different types of serotonin receptors is a source of the variability in serotonergic effects, four selective agonists of serotonin receptors in the serotonin (5-HT) 1 and 5-HT2 families were iontophoretically applied to IC neurons, which were monitored for changes in their responses to auditory stimuli. Different agonists had different effects on neural responses. The 5-HT1A agonist had mixed facilitatory and depressive effects, whereas 5-HT1B and 5-HT2C agonists were both largely facilitatory. Different agonists changed threshold and frequency tuning in ways that reflected their effects on spike count. When pairs of agonists were applied sequentially to the same neurons, selective agonists sometimes affected neurons in ways that were similar to serotonin, but not to other selective agonists tested. Different agonists also differentially affected groups of neurons classified by the shapes of their frequency-tuning curves, with serotonin and the 5-HT1 receptors affecting proportionally more non-V-type neurons relative to the other agonists tested. In all, evidence suggests that the diversity of serotonin receptor subtypes in the IC is likely to account for at least some of the variability of the effects of serotonin and that receptor subtypes fulfill specialized roles in auditory processing. PMID:16870843

  16. Defining Nicotinic Agonist Binding Surfaces through Photoaffinity Labeling†

    PubMed Central

    Tomizawa, Motohiro; Maltby, David; Medzihradszky, Katalin F.; Zhang, Nanjing; Durkin, Kathleen A.; Presley, Jack; Talley, Todd T.; Taylor, Palmer; Burlingame, Alma L.; Casida, John E.

    2016-01-01

    Nicotinic acetylcholine (ACh) receptor (nAChR) agonists are potential therapeutic agents for neurological dysfunction. In the present study, the homopentameric mollusk ACh binding protein (AChBP), used as a surrogate for the extracellular ligand-binding domain of the nAChR, was specifically derivatized by the highly potent agonist azidoepibatidine (AzEPI) prepared as a photoaffinity probe and radioligand. One EPI-nitrene photoactivated molecule was incorporated in each subunit interface binding site based on analysis of the intact derivatized protein. Tryptic fragments of the modified AChBP were analyzed by collision-induced dissociation and Edman sequencing of radiolabeled peptides. Each specific EPI-nitrene-modified site involved either Tyr195 of loop C on the principal or (+)-face or Met116 of loop E on the complementary or (−)-face. The two derivatization sites were observed in similar frequency, providing evidence of the reactivity of the azido/nitrene probe substituent and close proximity to both residues. [3H]AzEPI binds to the α4β2 nAChR at a single high-affinity site and photoaffinity-labels only the α4 subunit, presumably modifying Tyr225 spatially corresponding to Tyr195 of AChBP. Phe137 of the β2 nAChR subunit, equivalent to Met116 of AChBP, conceivably lacks sufficient reactivity with the nitrene generated from the probe. The present photoaffinity labeling in a physiologically relevant condition combined with the crystal structure of AChBP allows development of precise structural models for the AzEPI interactions with AChBP and α4β2 nAChR. These findings enabled us to use AChBP as a structural surrogate to define the nAChR agonist site. PMID:17614369

  17. INSIGHT AGONISTES: A READING OF SOPHOCLES'S OEDIPUS THE KING.

    PubMed

    Mahon, Eugene J

    2015-07-01

    In this reading of Sophocles's Oedipus the King, the author suggests that insight can be thought of as the main protagonist of the tragedy. He personifies this depiction of insight, calling it Insight Agonistes, as if it were the sole conflicted character on the stage, albeit masquerading at times as several other characters, including gods, sphinxes, and oracles. This psychoanalytic reading of the text lends itself to an analogy between psychoanalytic process and Sophocles's tragic hero. The author views insight as always transgressing against, always at war with a conservative, societal, or intrapsychic chorus of structured elements. A clinical vignette is presented to illustrate this view of insight.

  18. Narrow SAR in odorant sensing Orco receptor agonists.

    PubMed

    Romaine, Ian M; Taylor, Robert W; Saidu, Samsudeen P; Kim, Kwangho; Sulikowski, Gary A; Zwiebel, Laurence J; Waterson, Alex G

    2014-06-15

    The systematic exploration of a series of triazole-based agonists of the cation channel insect odorant receptor is reported. The structure-activity relationships of independent sections of the molecules are examined. Very small changes to the compound structure were found to exert a large impact on compound activity. Optimal substitutions were combined using a 'mix-and-match' strategy to produce best-in-class compounds that are capable of potently agonizing odorant receptor activity and may form the basis for the identification of a new mode of insect behavior modification. PMID:24813736

  19. Clenbuterol, a beta(2)-agonist, retards atrophy in denervated muscles

    NASA Technical Reports Server (NTRS)

    Zeman, Richard J.; Ludemann, Robert; Etlinger, Joseph D.

    1987-01-01

    The effects of a beta(2) agonist, clenbuterol, on the protein content as well as on the contractile strength and the muscle fiber cross-sectional area of various denervated muscles from rats were investigated. It was found that denervated soleus, anterior tibialis, and gastrocnemius muscles, but not the extensor digitorum longus, of rats treated for 2-3 weeks with clenbuterol contained 95-110 percent more protein than denervated controls. The twofold difference in the protein content of denervated solei was paralleled by similar changes in contractile strength and muscle fiber cross-sectional area.

  20. INSIGHT AGONISTES: A READING OF SOPHOCLES'S OEDIPUS THE KING.

    PubMed

    Mahon, Eugene J

    2015-07-01

    In this reading of Sophocles's Oedipus the King, the author suggests that insight can be thought of as the main protagonist of the tragedy. He personifies this depiction of insight, calling it Insight Agonistes, as if it were the sole conflicted character on the stage, albeit masquerading at times as several other characters, including gods, sphinxes, and oracles. This psychoanalytic reading of the text lends itself to an analogy between psychoanalytic process and Sophocles's tragic hero. The author views insight as always transgressing against, always at war with a conservative, societal, or intrapsychic chorus of structured elements. A clinical vignette is presented to illustrate this view of insight. PMID:26198605

  1. Induction of depersonalization by the serotonin agonist meta-chlorophenylpiperazine.

    PubMed

    Simeon, D; Hollander, E; Stein, D J; DeCaria, C; Cohen, L J; Saoud, J B; Islam, N; Hwang, M

    1995-09-29

    Sixty-seven subjects, including normal volunteers and patients with obsessive-compulsive disorder, social phobia, and borderline personality disorder, received ratings of depersonalization after double-blind, placebo-controlled challenges with the partial serotonin agonist meta-chlorophenylpiperazine (m-CPP). Challenge with m-CPP induced depersonalization significantly more than did placebo. Subjects who became depersonalized did not differ in age, sex, or diagnosis from those who did not experience depersonalization. There was a significant correlation between the induction of depersonalization and increase in panic, but not nervousness, anxiety, sadness, depression, or drowsiness. This report suggests that serotonergic dysregulation may in part underlie depersonalization.

  2. Estrogen Receptor Agonists and Antagonists in the Yeast Estrogen Bioassay.

    PubMed

    Wang, Si; Bovee, Toine F H

    2016-01-01

    Cell-based bioassays can be used to predict the eventual biological activity of a substance on a living organism. In vitro reporter gene bioassays are based on recombinant vertebrate cell lines or yeast strains and especially the latter are easy-to-handle, cheap, and fast. Moreover, yeast cells do not express estrogen, androgen, progesterone or glucocorticoid receptors, and are thus powerful tools in the development of specific reporter gene systems that are devoid of crosstalk from other hormone pathways. This chapter describes our experience with an in-house developed RIKILT yeast estrogen bioassay for testing estrogen receptor agonists and antagonists, focusing on the applicability of the latter. PMID:26585147

  3. Discovery of a potent and selective GPR120 agonist.

    PubMed

    Shimpukade, Bharat; Hudson, Brian D; Hovgaard, Christine Kiel; Milligan, Graeme; Ulven, Trond

    2012-05-10

    GPR120 is a receptor of unsaturated long-chain fatty acids reported to mediate GLP-1 secretion, insulin sensitization, anti-inflammatory, and anti-obesity effects and is therefore emerging as a new potential target for treatment of type 2 diabetes and metabolic diseases. Further investigation is however hindered by the lack of suitable receptor modulators. Screening of FFA1 ligands provided a lead with moderate activity on GPR120 and moderate selectivity over FFA1. Optimization led to the discovery of the first potent and selective GPR120 agonist.

  4. Phosphatidic acid-induced contraction in guinea-pig taenia coli.

    PubMed

    Ohata, H; Momose, K

    1990-06-01

    Natural phosphatidic acid from egg yolk lecithin (PA) caused a sustained contraction in guinea-pig taenia coli. The contractile response to PA was concentration-dependent (10(-6)-10(-4) M) in the normal medium and the maximal response to PA was about 20% of the response to carbachol (CCh) at 10(-6) M. Phospholipase D mimicked PA-induced contraction. This result suggests that increase in endogenous PA can induce contraction. The PA-induced contraction was not inhibited by atropine (10(-6) M). The contraction was more dependent on concentration of extracellular Ca2+ than CCh-induced contraction. PA increased 45Ca2+ uptake into the tissue. These results suggest that the PA-induced contraction results from increase in Ca2+ influx across plasma membranes, but not release of Ca2+ from intracellular stores in guinea-pig taenia coli. The PA-induced contraction was inhibited to 42% of the control response by propyl gallate (0.2 mM), a combined inhibitor of cyclooxygenase and lipoxygenase. This result indicates that a portion of the contraction is related to release of arachidonic acid and its metabolites, and the other portions are based on direct action of PA. These results suggest a possibility that increased PA by agonist stimulation is related to the following extracellular Ca2(+)-dependent contraction.

  5. Contamination with retinoic acid receptor agonists in two rivers in the Kinki region of Japan.

    PubMed

    Inoue, Daisuke; Nakama, Koki; Sawada, Kazuko; Watanabe, Taro; Takagi, Mai; Sei, Kazunari; Yang, Min; Hirotsuji, Junji; Hu, Jianying; Nishikawa, Jun-ichi; Nakanishi, Tsuyoshi; Ike, Michihiko

    2010-04-01

    This study was conducted to investigate the agonistic activity against human retinoic acid receptor (RAR) alpha in the Lake Biwa-Yodo River and the Ina River in the Kinki region of Japan. To accomplish this, a yeast two-hybrid assay was used to elucidate the spatial and temporal variations and potential sources of RARalpha agonist contamination in the river basins. RARalpha agonistic activity was commonly detected in the surface water samples collected along two rivers at different periods, with maximum all-trans retinoic acid (atRA) equivalents of 47.6 ng-atRA/L and 23.5 ng-atRA/L being observed in Lake Biwa-Yodo River and Ina River, respectively. The results indicated that RARalpha agonists are always present and widespread in the rivers. Comparative investigation of RARalpha and estrogen receptor alpha agonistic activities at 20 stations along each river revealed that the spatial variation pattern of RARalpha agonist contamination was entirely different from that of the estrogenic compound contamination. This suggests that the effluent from municipal wastewater treatment plants, a primary source of estrogenic compounds, seemed not to be the cause of RARalpha agonist contamination in the rivers. Fractionation using high performance liquid chromatography (HPLC) directed by the bioassay found two bioactive fractions from river water samples, suggesting the presence of at least two RARalpha agonists in the rivers. Although a trial conducted to identify RARalpha agonists in the major bioactive fraction was not completed as part of this study, comparison of retention times in HPLC analysis and quantification with liquid chromatography-mass spectrometry analysis revealed that the major causative contaminants responsible for the RARalpha agonistic activity were not RAs (natural RAR ligands) and 4-oxo-RAs, while 4-oxo-RAs were identified as the major RAR agonists in sewage in Beijing, China. These findings suggest that there are unknown RARalpha agonists with high

  6. Substituted isoxazole analogs of farnesoid X receptor (FXR) agonist GW4064

    SciTech Connect

    Bass, Jonathan Y.; Caldwell, Richard D.; Caravella, Justin A.; Chen, Lihong; Creech, Katrina L.; Deaton, David N.; Madauss, Kevin P.; Marr, Harry B.; McFadyen, Robert B.; Miller, Aaron B.; Parks, Derek J.; Todd, Dan; Williams, Shawn P.; Wisely, G. Bruce

    2010-09-27

    Starting from the known FXR agonist GW 4064 1a, a series of alternately 3,5-substituted isoxazoles was prepared. Several of these analogs were potent full FXR agonists. A subset of this series, with a tether between the isoxazole ring and the 3-position aryl substituent, were equipotent FXR agonists to GW 4064 1a, with the 2,6-dimethyl phenol analog 1t having greater FRET FXR potency than GW 4064 1a.

  7. Substituted isoxazole analogs of farnesoid X receptor (FXR) agonist GW4064.

    PubMed

    Bass, Jonathan Y; Caldwell, Richard D; Caravella, Justin A; Chen, Lihong; Creech, Katrina L; Deaton, David N; Madauss, Kevin P; Marr, Harry B; McFadyen, Robert B; Miller, Aaron B; Parks, Derek J; Todd, Dan; Williams, Shawn P; Wisely, G Bruce

    2009-06-01

    Starting from the known FXR agonist GW 4064 1a, a series of alternately 3,5-substituted isoxazoles was prepared. Several of these analogs were potent full FXR agonists. A subset of this series, with a tether between the isoxazole ring and the 3-position aryl substituent, were equipotent FXR agonists to GW 4064 1a, with the 2,6-dimethyl phenol analog 1t having greater FRET FXR potency than GW 4064 1a.

  8. Discovery of potent and selective nonsteroidal indazolyl amide glucocorticoid receptor agonists.

    PubMed

    Sheppeck, James E; Gilmore, John L; Xiao, Hai-Yun; Dhar, T G Murali; Nirschl, David; Doweyko, Arthur M; Sack, Jack S; Corbett, Martin J; Malley, Mary F; Gougoutas, Jack Z; Mckay, Lorraine; Cunningham, Mark D; Habte, Sium F; Dodd, John H; Nadler, Steven G; Somerville, John E; Barrish, Joel C

    2013-10-01

    Modification of a phenolic lead structure based on lessons learned from increasing the potency of steroidal glucocorticoid agonists lead to the discovery of exceptionally potent, nonsteroidal, indazole GR agonists. SAR was developed to achieve good selectivity against other nuclear hormone receptors with the ultimate goal of achieving a dissociated GR agonist as measured by human in vitro assays. The specific interactions by which this class of compounds inhibits GR was elucidated by solving an X-ray co-crystal structure. PMID:23953070

  9. In vitro and in vivo efficacy of a potent opioid receptor agonist, biphalin, compared to subtype-selective opioid receptor agonists for stroke treatment

    PubMed Central

    Yang, Li; Islam, Mohammad R; Karamyan, Vardan T.; Abbruscato, Thomas J.

    2015-01-01

    To meet the challenge of identification of new treatments for stroke, this study was designed to evaluate a potent, nonselective opioid receptor (OR) agonist, biphalin, in comparison to subtype selective OR agonists, as a potential neuroprotective drug candidate using in vitro and in vivo models of ischemic stroke. Our in vitro approach included mouse primary neuronal cells that were challenged with glutamate and hypoxic/aglycemic (H/A) conditions. We observed that 10 nM biphalin, exerted a statistically significant neuroprotective effect after glutamate challenge, compared to all selective opioid agonists, according to lactate dehydrogenase (LDH) and 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assays. Moreover, 10 nM biphalin provided superior neuroprotection after H/A-reoxygenation compared to selective opioid agonists in all cases. Our in vitro investigations were supported by in vivo studies which indicate that the nonselective opioid agonist, biphalin, achieves enhanced neuroprotective potency compared to any of the selective opioid agonists, evidenced by reduced edema and infarct ratios. Reduction of edema and infarction was accompanied by neurological improvement of the animals in two independent behavioral tests. Collectively these data strongly suggest that concurrent agonist stimulation of mu, kappa and delta ORs with biphalin is neuroprotective and superior to neuroprotection by activation of any single OR subtype. PMID:25801116

  10. Effects of LAAM and methadone utilization in an opiate agonist treatment program.

    PubMed

    Valdivia, J F; Khattak, S

    2000-01-01

    The development and approval of levo-alpha-acetylmethadol (LAAM) as a pharmacotherapeutic agent in opioid agonist therapy provided an alternative to methadone. Clinicians recognized the potential benefits that LAAM, a synthetic mu agonist with pharmacological properties which differ from those of methadone,could have in the treatment management of addicts in opioid agonist therapy. We report our experience utilizing LAAM from 1995 to 1999 at the Hines VA opioid agonist therapy clinic. The addition of LAAM to the clinic's treatment armamentarium has resulted in management options that have improved the areas of patient recruitment, patient retention, patient traffic, take-home medication, detoxification, and treatment outcomes.

  11. Trial Watch: Immunostimulation with Toll-like receptor agonists in cancer therapy

    PubMed Central

    Iribarren, Kristina; Bloy, Norma; Buqué, Aitziber; Cremer, Isabelle; Eggermont, Alexander; Fridman, Wolf Hervé; Fucikova, Jitka; Galon, Jérôme; Špíšek, Radek; Zitvogel, Laurence; Kroemer, Guido; Galluzzi, Lorenzo

    2016-01-01

    ABSTRACT Accumulating preclinical evidence indicates that Toll-like receptor (TLR) agonists efficiently boost tumor-targeting immune responses (re)initiated by most, if not all, paradigms of anticancer immunotherapy. Moreover, TLR agonists have been successfully employed to ameliorate the efficacy of various chemotherapeutics and targeted anticancer agents, at least in rodent tumor models. So far, only three TLR agonists have been approved by regulatory agencies for use in cancer patients. Moreover, over the past decade, the interest of scientists and clinicians in these immunostimulatory agents has been fluctuating. Here, we summarize recent advances in the preclinical and clinical development of TLR agonists for cancer therapy. PMID:27141345

  12. Dopamine agonist-induced substance addiction: the next piece of the puzzle.

    PubMed

    Evans, Andrew

    2011-02-01

    Traditional antiparkinson treatment strategies strive to balance the antiparkinson effects of dopaminergic drugs with the avoidance of motor response complications. Dopamine agonists have an established role in delaying the emergence of motor response complications or reducing motor "off" periods. The recent recognition of a range of "behavioural addictions" that are linked to dopamine agonist use has highlighted the role of dopamine in brain reward function and addiction disorders in general. Dopamine agonists have now even been linked occasionally to new substance addictions. The challenge now for the Parkinsonologist is to also balance the net benefits of using dopamine agonists for their motor effects with avoiding the harm from behavioural compulsions. PMID:20980151

  13. Structural complexes of the agonist, inverse agonist and antagonist bound C5a receptor: insights into pharmacology and signaling.

    PubMed

    Rana, Soumendra; Sahoo, Amita Rani; Majhi, Bharat Kumar

    2016-04-26

    The C5a receptor (C5aR) is a pharmacologically important G-protein coupled receptor (GPCR) that interacts with (h)C5a, by recruiting both the "orthosteric" sites (site1 at the N-terminus and site2 at the ECS, extra cellular surface) on C5aR in a two site-binding model. However, the complex pharmacological landscape and the distinguishing chemistry operating either at the "orthosteric" site1 or at the functionally important "orthosteric" site2 of C5aR are still not clear, which greatly limits the understanding of C5aR pharmacology. One of the major bottlenecks is the lack of an experimental structure or a refined model structure of C5aR with appropriately defined active sites. The study attempts to understand the pharmacology at the "orthosteric" site2 of C5aR rationally by generating a highly refined full-blown model structure of C5aR through advanced molecular modeling techniques, and further subjecting it to automated docking and molecular dynamics (MD) studies in the POPC bilayer. The first series of structural complexes of C5aR respectively bound to a linear native peptide agonist ((h)C5a-CT), a small molecule inverse agonist (NDT) and a cyclic peptide antagonist (PMX53) are reported, apparently establishing the unique pharmacological landscape of the "orthosteric" site2, which also illustrates an energetically distinct but coherent competitive chemistry ("cation-π" vs. "π-π" interactions) involved in distinguishing the established ligands known for targeting the "orthosteric" site2 of C5aR. Over a total of 1 μs molecular dynamics (MD) simulation in the POPC bilayer, it is evidenced that while the agonist prefers a "cation-π" interaction, the inverse agonist prefers a "cogwheel/L-shaped" interaction in contrast to the "edge-to-face/T-shaped" type π-π interactions demonstrated by the antagonist by engaging the F275(7.28) of the C5aR. In the absence of a NMR or crystallographically guided model structure of C5aR, the computational model complexes not only

  14. Serotonergic agonists stimulate inositol lipid metabolism in rabbit platelets

    SciTech Connect

    Schaechter, M.; Godfrey, P.P.; Minchin, M.C.W.; McClue, S.J.; Young, M.M.

    1985-10-28

    The metabolism of inositol phospholipids in response to serotonergic agonists was investigated in rabbit platelets. In platelets prelabelled with (/sup 3/H)-inositol, in a medium containing 10 mM LiCl which blocks the enzyme inositol-1-phosphatase, 5-hydroxytryptamine (5-HT) caused a dose-dependent accumulation of inositol phosphates (IP). This suggests a phospholipase-C-mediated breakdown of phosphoinositides. Ketanserin, a selective 5-HT/sub 2/ antagonist, was a potent inhibitor of the 5-HT response, with a Ki of 28 nM, indicating that 5-HT is activating receptors of the 5-HT/sub 2/ type in the platelet. Lysergic acid diethylamide (LSD) and quipazine also caused dose-related increases in inositol phosphate levels, though these were considerably less than those produced by 5-HT. These results show that relatively small changes in phosphoinositide metabolism induced by serotonergic agonists can be investigated in the rabbit platelet, and this cell may therefore be a useful model for the study of some 5-HT receptors. 30 references, 4 figures.

  15. Long-Acting Beta Agonists Enhance Allergic Airway Disease

    PubMed Central

    Knight, John M.; Mak, Garbo; Shaw, Joanne; Porter, Paul; McDermott, Catherine; Roberts, Luz; You, Ran; Yuan, Xiaoyi; Millien, Valentine O.; Qian, Yuping; Song, Li-Zhen; Frazier, Vincent; Kim, Choel; Kim, Jeong Joo; Bond, Richard A.; Milner, Joshua D.; Zhang, Yuan; Mandal, Pijus K.; Luong, Amber; Kheradmand, Farrah

    2015-01-01

    Asthma is one of the most common of medical illnesses and is treated in part by drugs that activate the beta-2-adrenoceptor (β2-AR) to dilate obstructed airways. Such drugs include long acting beta agonists (LABAs) that are paradoxically linked to excess asthma-related mortality. Here we show that LABAs such as salmeterol and structurally related β2-AR drugs such as formoterol and carvedilol, but not short-acting agonists (SABAs) such as albuterol, promote exaggerated asthma-like allergic airway disease and enhanced airway constriction in mice. We demonstrate that salmeterol aberrantly promotes activation of the allergic disease-related transcription factor signal transducer and activator of transcription 6 (STAT6) in multiple mouse and human cells. A novel inhibitor of STAT6, PM-242H, inhibited initiation of allergic disease induced by airway fungal challenge, reversed established allergic airway disease in mice, and blocked salmeterol-dependent enhanced allergic airway disease. Thus, structurally related β2-AR ligands aberrantly activate STAT6 and promote allergic airway disease. This untoward pharmacological property likely explains adverse outcomes observed with LABAs, which may be overcome by agents that antagonize STAT6. PMID:26605551

  16. Agonistic induction of PPARγ reverses cigarette smoke–induced emphysema

    PubMed Central

    Shan, Ming; You, Ran; Yuan, Xiaoyi; Frazier, Michael V.; Porter, Paul; Seryshev, Alexander; Hong, Jeong-Soo; Song, Li-zhen; Zhang, Yiqun; Hilsenbeck, Susan; Whitehead, Lawrence; Zarinkamar, Nazanin; Perusich, Sarah; Corry, David B.; Kheradmand, Farrah

    2014-01-01

    The development of emphysema in humans and mice exposed to cigarette smoke is promoted by activation of an adaptive immune response. Lung myeloid dendritic cells (mDCs) derived from cigarette smokers activate autoreactive Th1 and Th17 cells. mDC-dependent activation of T cell subsets requires expression of the SPP1 gene, which encodes osteopontin (OPN), a pleiotropic cytokine implicated in autoimmune responses. The upstream molecular events that promote SPP1 expression and activate mDCs in response to smoke remain unknown. Here, we show that peroxisome proliferator–activated receptor γ (PPARG/Pparg) expression was downregulated in mDCs of smokers with emphysema and mice exposed to chronic smoke. Conditional knockout of PPARγ in APCs using Cd11c-Cre Ppargflox/flox mice led to spontaneous lung inflammation and emphysema that resembled the phenotype of smoke-exposed mice. The inflammatory phenotype of Cd11c-Cre Ppargflox/flox mice required OPN, suggesting an antiinflammatory mechanism in which PPARγ negatively regulates Spp1 expression in the lung. A 2-month treatment with a PPARγ agonist reversed emphysema in WT mice despite continual smoke exposure. Furthermore, endogenous PPARγ agonists were reduced in the plasma of smokers with emphysema. These findings reveal a proinflammatory pathway, in which reduced PPARγ activity promotes emphysema, and suggest that targeting this pathway in smokers could prevent and reverse emphysema. PMID:24569375

  17. A novel PPARgamma agonist monascin's potential application in diabetes prevention.

    PubMed

    Hsu, Wei-Hsuan; Pan, Tzu-Ming

    2014-07-25

    Edible fungi of the Monascus species have been used as traditional Chinese medicine in eastern Asia for several centuries. Monascus-fermented products possess a number of functional secondary metabolites, including the anti-inflammatory pigments monascin and ankaflavin. Monascin has been shown to prevent or ameliorate several conditions, including hypercholesterolemia, hyperlipidemia, diabetes, and obesity. Recently, monascin has been shown to improve hyperglycemia, attenuate oxidative stress, inhibit insulin resistance, and suppress inflammatory cytokine production. In our recent study, we have found that monascin is a peroxisome proliferator-activated receptor-gamma (PPARgamma) agonist. The PPARgamma agonist activity had been investigated and its exerted benefits are inhibition of inflammation in methylglyoxal (MG)-treated rats, prevention of pancreas impairment causing advanced glycation endproducts (AGEs), promotion of insulin expression in vivo and in vitro, and attenuated carboxymethyllysine (CML)-induced hepatic stellate cell (HSC) activation in the past several years. Moreover, our studies also demonstrated that monascin also activated nuclear factor-erythroid 2-related factor 2 (Nrf2) in pancreatic RIN-m5F cell line thereby invading methylglyoxal induced pancreas dysfunction. In this review, we focus on the chemo-preventive properties of monascin against metabolic syndrome through PPARgamma and Nrf2 pathways. PMID:24752777

  18. Nicotinic acetylcholine receptor agonist attenuates ILC2-dependent airway hyperreactivity

    PubMed Central

    Galle-Treger, Lauriane; Suzuki, Yuzo; Patel, Nisheel; Sankaranarayanan, Ishwarya; Aron, Jennifer L.; Maazi, Hadi; Chen, Lin; Akbari, Omid

    2016-01-01

    Allergic asthma is a complex and chronic inflammatory disorder that is associated with airway hyperreactivity (AHR) and driven by Th2 cytokine secretion. Type 2 innate lymphoid cells (ILC2s) produce large amounts of Th2 cytokines and contribute to the development of AHR. Here, we show that ILC2s express the α7-nicotinic acetylcholine receptor (α7nAChR), which is thought to have an anti-inflammatory role in several inflammatory diseases. We show that engagement of a specific agonist with α7nAChR on ILC2s reduces ILC2 effector function and represses ILC2-dependent AHR, while decreasing expression of ILC2 key transcription factor GATA-3 and critical inflammatory modulator NF-κB, and reducing phosphorylation of upstream kinase IKKα/β. Additionally, the specific α7nAChR agonist reduces cytokine production and AHR in a humanized ILC2 mouse model. Collectively, our data suggest that α7nAChR expressed by ILC2s is a potential therapeutic target for the treatment of ILC2-mediated asthma. PMID:27752043

  19. A novel PPARgamma agonist monascin's potential application in diabetes prevention.

    PubMed

    Hsu, Wei-Hsuan; Pan, Tzu-Ming

    2014-07-25

    Edible fungi of the Monascus species have been used as traditional Chinese medicine in eastern Asia for several centuries. Monascus-fermented products possess a number of functional secondary metabolites, including the anti-inflammatory pigments monascin and ankaflavin. Monascin has been shown to prevent or ameliorate several conditions, including hypercholesterolemia, hyperlipidemia, diabetes, and obesity. Recently, monascin has been shown to improve hyperglycemia, attenuate oxidative stress, inhibit insulin resistance, and suppress inflammatory cytokine production. In our recent study, we have found that monascin is a peroxisome proliferator-activated receptor-gamma (PPARgamma) agonist. The PPARgamma agonist activity had been investigated and its exerted benefits are inhibition of inflammation in methylglyoxal (MG)-treated rats, prevention of pancreas impairment causing advanced glycation endproducts (AGEs), promotion of insulin expression in vivo and in vitro, and attenuated carboxymethyllysine (CML)-induced hepatic stellate cell (HSC) activation in the past several years. Moreover, our studies also demonstrated that monascin also activated nuclear factor-erythroid 2-related factor 2 (Nrf2) in pancreatic RIN-m5F cell line thereby invading methylglyoxal induced pancreas dysfunction. In this review, we focus on the chemo-preventive properties of monascin against metabolic syndrome through PPARgamma and Nrf2 pathways.

  20. Mood disorders, circadian rhythms, melatonin and melatonin agonists.

    PubMed

    Quera Salva, M A; Hartley, S

    2012-01-01

    Recent advances in the understanding of circadian rhythms have led to an interest in the treatment of major depressive disorder with chronobiotic agents. Many tissues have autonomous circadian rhythms, which are orchestrated by the master clock, situated in the suprachiasmatic nucleus (SNC). Melatonin (N-acetyl-5-hydroxytryptamine) is secreted from the pineal gland during darkness. Melatonin acts mainly on MT1 and MT2 receptors, which are present in the SNC, regulating physiological and neuroendocrine functions, including circadian entrainment, referred to as the chronobiotic effet. Circadian rhythms has been shown to be either misaligned or phase shifted or decreased in amplitude in both acute episodes and relapse of major depressive disorder (MDD) and bipolar disorder. Manipulation of circadian rhythms either using physical treatments (such as high intensity light) or behavioral therapy has shown promise in improving symptoms. Pharmacotherapy using melatonin and pure melatonin receptor agonists, while improving sleep, has not been shown to improve symptoms of depression. A novel antidepressant, agomelatine, combines 5HT2c antagonist and melatonin agonist action, and has shown promise in both acute treatment of MDD and in preventing relapse.

  1. Pindolol--the pharmacology of a partial agonist.

    PubMed Central

    Clark, B J; Menninger, K; Bertholet, A

    1982-01-01

    1 Pindolol is a non-selective beta-adrenoceptor blocking agent; its affinity to adrenoceptors in guinea pig atria (beta 1) is not significantly different from that in guinea pig trachea (beta 1 + beta 2) and canine vascular smooth muscle (beta 2). 2 Pindolol displays a striking diversity of agonist activities in isolated tissues. Stimulant effects correspond to 40--50% of the maximum effects of isoprenaline in isolated kitten atria and guinea pig trachea and to only 10% in guinea pig atria. Effects in canine isolated mesenteric vessels are those of a full agonist, maximum responses equaling those of isoprenaline. These findings suggest that the stimulant effects of pindolol are exerted principally on beta 2-adrenoceptors. 3 Cardiac stimulation produced by pindolol in the dog is sufficient to compensate for the cardiac depression resulting from blockade of beta-adrenoceptors in the heart. Reductions in cardiac output and compensatory increases in total peripheral resistance do not occur or are much smaller than those produced by beta-adrenoceptor blocking agents lacking sympathomimetic activity. 4 Pindolol-induced relaxation of bronchial smooth muscle prevents or minimizes the bronchoconstrictor effects of injected spasmogens in the cat. 5 Pindolol has marked vasodilator activity, small doses reducing femoral and mesenteric vascular resistance by approximately 30%. Doses comparable to those used in hypertensive patients lower blood pressure by 20 mmHg in non-anaesthetized dogs. PMID:7049208

  2. Pharmacology and toxicology of Cannabis derivatives and endocannabinoid agonists.

    PubMed

    Gerra, Gilberto; Zaimovic, Amir; Gerra, Maria L; Ciccocioppo, Roberto; Cippitelli, Andrea; Serpelloni, Giovanni; Somaini, Lorenzo

    2010-01-01

    For centuries Cannabis sativa and cannabis extracts have been used in natural medicine. Delta(9)-tetrahydrocannabinol (THC) is the main active ingredient of Cannabis. THC seems to be responsible for most of the pharmacological and therapeutic actions of cannabis. In a few countries THC extracts (i.e. Sativex) or THC derivatives such as nabilone, and dronabinol are used in the clinic for the treatment of several pathological conditions like chemotherapy-induced nausea and vomiting, multiple sclerosis and glaucoma. On the other hand the severe side effects and the high abuse liability of these agents represent a serious limitation in their medical use. In addition, diversion in the use of these active ingredients for recreational purpose is a concern. Over recent years, alternative approaches using synthetic cannabinoid receptor agonists or agents acting as activators of the endocannabinoid systems are under scrutiny with the hope to develop more effective and safer clinical applications. Likely, in the near future few of these new molecules will be available for clinical use. The present article review recent study and patents with focus on the cannabinoid system as a target for the treatment of central nervous system disorders with emphasis on agonists. PMID:19832688

  3. Pharmacology and toxicology of Cannabis derivatives and endocannabinoid agonists.

    PubMed

    Gerra, Gilberto; Zaimovic, Amir; Gerra, Maria L; Ciccocioppo, Roberto; Cippitelli, Andrea; Serpelloni, Giovanni; Somaini, Lorenzo

    2010-01-01

    For centuries Cannabis sativa and cannabis extracts have been used in natural medicine. Delta(9)-tetrahydrocannabinol (THC) is the main active ingredient of Cannabis. THC seems to be responsible for most of the pharmacological and therapeutic actions of cannabis. In a few countries THC extracts (i.e. Sativex) or THC derivatives such as nabilone, and dronabinol are used in the clinic for the treatment of several pathological conditions like chemotherapy-induced nausea and vomiting, multiple sclerosis and glaucoma. On the other hand the severe side effects and the high abuse liability of these agents represent a serious limitation in their medical use. In addition, diversion in the use of these active ingredients for recreational purpose is a concern. Over recent years, alternative approaches using synthetic cannabinoid receptor agonists or agents acting as activators of the endocannabinoid systems are under scrutiny with the hope to develop more effective and safer clinical applications. Likely, in the near future few of these new molecules will be available for clinical use. The present article review recent study and patents with focus on the cannabinoid system as a target for the treatment of central nervous system disorders with emphasis on agonists.

  4. Identification of agonists for a group of human odorant receptors

    PubMed Central

    Gonzalez-Kristeller, Daniela C.; do Nascimento, João B. P.; Galante, Pedro A. F.; Malnic, Bettina

    2015-01-01

    Olfaction plays a critical role in several aspects of the human life. Odorants are detected by hundreds of odorant receptors (ORs) which belong to the superfamily of G protein-coupled receptors. These receptors are expressed in the olfactory sensory neurons of the nose. The information provided by the activation of different combinations of ORs in the nose is transmitted to the brain, leading to odorant perception and emotional and behavioral responses. There are ~400 intact human ORs, and to date only a small percentage of these receptors (~10%) have known agonists. The determination of the specificity of the human ORs will contribute to a better understanding of how odorants are discriminated by the olfactory system. In this work, we aimed to identify human specific ORs, that is, ORs that are present in humans but absent from other species, and their corresponding agonists. To do this, we first selected 22 OR gene sequences from the human genome with no counterparts in the mouse, rat or dog genomes. Then we used a heterologous expression system to screen a subset of these human ORs against a panel of odorants of biological relevance, including foodborne aroma volatiles. We found that different types of odorants are able to activate some of these previously uncharacterized human ORs. PMID:25784876

  5. How does agonistic behaviour differ in albino and pigmented fish?

    PubMed Central

    Horký, Pavel; Wackermannová, Marie

    2016-01-01

    In addition to hypopigmentation of the skin and red iris colouration, albino animals also display distinct physiological and behavioural alterations. However, information on the social interactions of albino animals is rare and has mostly been limited to specially bred strains of albino rodents and animals from unique environments in caves. Differentiating between the effects of albinism and domestication on behaviour in rodents can be difficult, and social behaviour in cave fish changes according to species-specific adaptations to conditions of permanent darkness. The agonistic behaviours of albino offspring of pigmented parents have yet to be described. In this study, we observed agonistic behaviour in albino and pigmented juvenile Silurus glanis catfish. We found that the total number of aggressive interactions was lower in albinos than in pigmented catfish. The distance between conspecifics was also analysed, and albinos showed a tendency towards greater separation from their same-coloured conspecifics compared with pigmented catfish. These results demonstrate that albinism can be associated with lower aggressiveness and with reduced shoaling behaviour preference, as demonstrated by a tendency towards greater separation of albinos from conspecifics. PMID:27114883

  6. [Ni(OH)3W6O18(OCH2)3CCH2OH]4–: the first tris-functionalized Anderson-type heteropolytungstate† †Electronic supplementary information (ESI) available: Experimental procedures, synthesis details, characterization data, including IR, ESI-MS, TGA, elemental analysis and X-ray crystallography with CIF file. CCDC 1477611. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6cc04326g Click here for additional data file. Click here for additional data file.

    PubMed Central

    Gumerova, Nadiia I.; Roller, Alexander

    2016-01-01

    Na2[TMA]2[Ni(OH)3W6O18(OCH2)3CCH2OH]·9H2O represents the first covalent tris-functionalized Anderson-type heteropolytungstate and was characterized by single-crystal X-ray diffraction, electrospray ionization mass spectrometry, TGA and IR spectroscopy. Zeta potential measurements in solutions containing human serum albumin were performed to investigate electrostatic interactions with [Ni(OH)3W6O18(OCH2)3CCH2OH]4–. PMID:27355393

  7. The direct l-type resonance spectrum of CF 3CCH in the vibrational state v10=3: Extension of the theory of reduction to H 6 n terms

    NASA Astrophysics Data System (ADS)

    Wötzel, U.; Mäder, H.; Harder, H.; Pracna, P.; Sarka, K.

    2006-01-01

    The direct l-type resonance spectrum of CF 3CCH has been measured in the v10=3 vibrational state by means of waveguide microwave Fourier transform spectroscopy in the range 8-26 GHz. Three types of direct l-type resonance transitions induced by the (Δ k=Δ l=±2) interaction could be observed: 140 transitions following the Δ J=0, Δ k=Δ l=±2, Δ| l|=0, selection rule covering values of J=17-61 and G=| k- l| from 1 to 7, 94 transitions following the Δ J=0, Δ k=Δ l=±2, Δ| l|=±2, selection rule covering values of J=26-57 and G from 15 to 24, 90 transitions following the Δ J=0, Δ k=Δ l=±4 selection rule covering values of J=34-80 and G from 3 to 12 and 13 transitions following the Δ J=0, Δ k=Δ l=±6, k=∓1, l=∓1⇔ k=±5, l=±3 selection rule for J=71-83. 14 A 1-A 2 splitting transitions with kl=+1 were measured from J=33 to 49. Strong perturbations due to Δ (k- l)=±3 interactions made possible the observation of perturbation-allowed transitions with selection rule k=±4, l=±3⇔ k=±3, l=∓1. Furthermore, the rotational transitions J=2-1, 3-2 and 4-3 have been measured. To make use of the multiple fitting concept, the theory of reduction developed for the vt=2 vibrational state by Sarka and Harder [K. Sarka, H. Harder, J. Mol. Spectrosc. 197 (1999) 254] has been extended to the vt=3 vibrational state including terms up to H 62. Owing to problems in the reproduction of data with low K and A 1-A 2 symmetry, two types of fits have been performed using five reduced forms of the effective Hamiltonian. The first type of fit used a reduced data set for which part of the transitions has been omitted. The unitary equivalence of the determined parameter sets has been demonstrated including newly derived relations for parameters in v10=3. In the second type of fit, the complete data set has been included, yielding satisfactory results only in one reduction. In both type of fits, parameters up to sixth order have been determined including the axial

  8. Modulation of PPAR subtype selectivity. Part 2: Transforming PPARα/γ dual agonist into α selective PPAR agonist through bioisosteric modification.

    PubMed

    Zaware, Pandurang; Shah, Shailesh R; Pingali, Harikishore; Makadia, Pankaj; Thube, Baban; Pola, Suresh; Patel, Darshit; Priyadarshini, Priyanka; Suthar, Dinesh; Shah, Maanan; Jamili, Jeevankumar; Sairam, Kalapatapu V V M; Giri, Suresh; Patel, Lala; Patel, Harilal; Sudani, Hareshkumar; Patel, Hiren; Jain, Mukul; Patel, Pankaj; Bahekar, Rajesh

    2011-01-15

    A novel series of oxime containing benzyl-1,3-dioxane-r-2-carboxylic acid derivatives (6a-k) were designed as selective PPARα agonists, through bioisosteric modification in the lipophilic tail region of PPARα/γ dual agonist. Some of the test compounds (6a, 6b, 6c and 6f) showed high selectivity towards PPARα over PPARγ in vitro. Further, highly potent and selective PPARα agonist 6c exhibited significant antihyperglycemic and antihyperlipidemic activity in vivo, along with its improved pharmacokinetic profile. Favorable in-silico interaction of 6c with PPARα binding pocket correlate its in vitro selectivity profile toward PPARα over PPARγ. Together, these results confirm discovery of novel series of oxime based selective PPARα agonists for the safe and effective treatment of various metabolic disorders. PMID:21195611

  9. Direct muscarinic and nicotinic receptor-mediated excitation of rat medial vestibular nucleus neurons in vitro

    NASA Technical Reports Server (NTRS)

    Phelan, K. D.; Gallagher, J. P.

    1992-01-01

    We have utilized intracellular recording techniques to investigate the cholinoceptivity of rat medial vestibular nucleus (MVN) neurons in a submerged brain slice preparation. Exogenous application of the mixed cholinergic agonists, acetylcholine (ACh) or carbachol (CCh), produced predominantly membrane depolarization, induction of action potential firing, and decreased input resistance. Application of the selective muscarinic receptor agonist muscarine (MUSC), or the selective nicotinic receptor agonists nicotine (NIC) or 1,1-dimethyl-4-phenylpiperazinium (DMPP) also produced membrane depolarizations. The MUSC-induced depolarization was accompanied by decreased conductance, while an increase in conductance appeared to underlie the NIC- and DMPP-induced depolarizations. The muscarinic and nicotinic receptor mediated depolarizations persisted in tetrodotoxin and/or low Ca2+/high Mg2+ containing media, suggesting direct postsynaptic receptor activation. The MUSC-induced depolarization could be reversibly blocked by the selective muscarinic-receptor antagonist, atropine, while the DMPP-induced depolarization could be reversibly suppressed by the selective ganglionic nicotinic-receptor antagonist, mecamylamine. Some neurons exhibited a transient membrane hyperpolarization during the depolarizing response to CCh or MUSC application. This transient inhibition could be reversibly blocked by the gamma-aminobutyric acid (GABA) antagonist, bicuculline, suggesting that the underlying hyperpolarization results indirectly from the endogenous release of GABA acting at GABA receptors. This study confirms the cholinoceptivity of MVN neurons and establishes that individual MVN cells possess muscarinic as well as nicotinic receptors. The data provide support for a prominent role of cholinergic mechanisms in the direct and indirect regulation of the excitability of MVN neurons.

  10. Benzodiazepine Site Agonists Differentially Alter Acetylcholine Release in Rat Amygdala

    PubMed Central

    Hambrecht-Wiedbusch, Viviane S.; Mitchell, Melinda F.; Firn, Kelsie A.; Baghdoyan, Helen A.; Lydic, Ralph

    2014-01-01

    Background Agonist binding at the benzodiazepine site of γ-aminobutric acid type A receptors diminishes anxiety and insomnia by actions in the amygdala. The neurochemical effects of benzodiazepine-site agonists remain incompletely understood. Cholinergic neurotransmission modulates amygdala function, and in this study we tested the hypothesis that benzodiazepine-site agonists alter acetylcholine (ACh) release in the amygdala. Methods Microdialysis and high performance liquid chromatography quantified ACh release in the amygdala of Sprague-Dawley rats (n=33). ACh was measured before and after IV administration (3 mg/kg) of midazolam or eszopiclone, with and without anesthesia. ACh in isoflurane-anesthetized rats during dialysis with Ringer’s solution(control) was compared to ACh release during dialysis with Ringer’s solution containing (100 μM) midazolam, diazepam, eszopiclone, or zolpidem. Results In unanesthetized rats, ACh in the amygdala was decreased by IV midazolam (−51.1%; P=0.0029; 95% CI= −73.0% to −29.2%) and eszopiclone (−39.6%; P=0.0222; 95% CI= −69.8% to −9.3%). In anesthetized rats, ACh in the amygdala was decreased by IV administration of midazolam (−46.2%; P=0.0041; 95% CI= −67.9% to −24.5%) and eszopiclone (−34.0%; P=0.0009; 95% CI= −44.7% to −23.3%), and increased by amygdala delivery of diazepam (43.2%; P=0.0434; 95% CI= 2.1% to 84.3%), and eszopiclone (222.2%; P=0.0159; 95% CI= 68.5% to 375.8%). Conclusions ACh release in the amygdala was decreased by IV delivery of midazolam and eszopiclone. Dialysis delivery directly into the amygdala caused either increased (eszopiclone and diazepam) or likely no significant change (midazolam and zolpidem) in ACh release. These contrasting effects of delivery route on ACh release support the interpretation that systemically administered midazolam and eszopiclone decrease ACh release in the amygdala by acting on neuronal systems outside of the amygdala. PMID:24842176

  11. Discriminative stimulus properties of indorenate, a serotonin agonist.

    PubMed Central

    Velázquez-Martínez, D N; López Cabrera, M; Sánchez, H; Ramírez, J I; Hong, E

    1999-01-01

    OBJECTIVE: To determine whether indorenate, a serotonin-receptor agonist, can exert discriminative control over operant responses, to establish the temporal course of discriminative control and to compare its stimulus properties to a (5-HT)IA receptor agonist. [3H]-8-hydroxy-2-(di-N-propylamino) tetralin (8-OH-DPAT). DESIGN: Prospective animal study. ANIMALS: Ten male Wistar rats. INTERVENTIONS: Rats were trained to press either of 2 levers for sucrose solution according to a fixed ratio schedule, which was gradually increased. Rats were given injections of either indorenate or saline solution during discrimination training. Once they had achieved an 83% accuracy rate, rats underwent generalization tests after having received a different dose of indorenate, the training dose of indorenate at various intervals before the test, various doses of 8-OH-DPT, or NAN-190 administered before indorenate or 8-OH-DPAT. OUTCOME MEASURES: Distribution of responses between the 2 levers before the first reinforcer of the session, response rate for all the responses in the session, and a discrimination index that expressed the drug-appropriate responses as a proportion of the total responses. RESULTS: Indorenate administration resulted in discriminative control over operant responses, maintained at fixed ratio 10, at a dose of 10.0 mg/kg (but not 3.0 mg/kg). When the interval between the administration of indorenate and the start of the session was varied, the time course of its cue properties followed that of its described effects on 5-HT turnover. In generalization tests, the discrimination index was a function of the dose of indorenate employed; moreover, administration of 8-OH-DPAT (from 0.1 to 1.0 mg/kg) fully mimicked the stimulus properties of indorenate in a dose-dependent way. The (5-HT)IA antagonist NAN-190 prevented the stimulus generalization from indorenate to 8-OH-DPAT. Also, NAN-190 antagonized the stimulus control of indorenate when administered 45 minutes before

  12. Impact of Efficacy at the μ-Opioid Receptor on Antinociceptive Effects of Combinations of μ-Opioid Receptor Agonists and Cannabinoid Receptor Agonists

    PubMed Central

    Maguire, David R.

    2014-01-01

    Cannabinoid receptor agonists, such as Δ9-tetrahydrocannabinol (Δ9-THC), enhance the antinociceptive effects of μ-opioid receptor agonists, which suggests that combining cannabinoids with opioids would improve pain treatment. Combinations with lower efficacy agonists might be preferred and could avoid adverse effects associated with large doses; however, it is unclear whether interactions between opioids and cannabinoids vary across drugs with different efficacy. The antinociceptive effects of μ-opioid receptor agonists alone and in combination with cannabinoid receptor agonists were studied in rhesus monkeys (n = 4) using a warm water tail withdrawal procedure. Etorphine, fentanyl, morphine, buprenorphine, nalbuphine, Δ9-THC, and CP 55,940 (2-[(1R,2R,5R)-5-hydroxy-2-(3-hydroxypropyl) cyclohexyl]-5-(2-methyloctan-2-yl)phenol) each increased tail withdrawal latency. Pretreatment with doses of Δ9-THC (1.0 mg/kg) or CP 55,940 (0.032 mg/kg) that were ineffective alone shifted the fentanyl dose-effect curve leftward 20.6- and 52.9-fold, respectively, and the etorphine dose-effect curve leftward 12.4- and 19.6-fold, respectively. Δ9-THC and CP 55,940 shifted the morphine dose-effect curve leftward only 3.4- and 7.9-fold, respectively, and the buprenorphine curve only 5.4- and 4.1-fold, respectively. Neither Δ9-THC nor CP 55,940 significantly altered the effects of nalbuphine. Cannabinoid receptor agonists increase the antinociceptive potency of higher efficacy opioid receptor agonists more than lower efficacy agonists; however, because much smaller doses of each drug can be administered in combinations while achieving adequate pain relief and that other (e.g., abuse-related) effects of opioids do not appear to be enhanced by cannabinoids, these results provide additional support for combining opioids with cannabinoids to treat pain. PMID:25194020

  13. Yawning and locomotor behavior induced by dopamine receptor agonists in mice and rats.

    PubMed

    Li, Su-Min; Collins, Gregory T; Paul, Noel M; Grundt, Peter; Newman, Amy H; Xu, Ming; Grandy, David K; Woods, James H; Katz, Jonathan L

    2010-05-01

    Dopaminergic (DA) agonist-induced yawning in rats seems to be mediated by DA D3 receptors, and low doses of several DA agonists decrease locomotor activity, an effect attributed to presynaptic D2 receptors. Effects of several DA agonists on yawning and locomotor activity were examined in rats and mice. Yawning was reliably produced in rats, and by the cholinergic agonist, physostigmine, in both the species. However, DA agonists were ineffective in producing yawning in Swiss-Webster or DA D2R and DA D3R knockout or wild-type mice. The drugs significantly decreased locomotor activity in rats at one or two low doses, with activity returning to control levels at higher doses. In mice, the drugs decreased locomotion across a 1000-10 000-fold range of doses, with activity at control levels (U-91356A) or above control levels [(+/-)-7-hydroxy-2-dipropylaminotetralin HBr, quinpirole] at the highest doses. Low doses of agonists decreased locomotion in all mice except the DA D2R knockout mice, but were not antagonized by DA D2R or D3R antagonists (L-741 626, BP 897, or PG01037). Yawning does not provide a selective in-vivo indicator of DA D3R agonist activity in mice. Decreases in mouse locomotor activity by the DA agonists seem to be mediated by D2 DA receptors.

  14. Prolonging Survival of Corneal Transplantation by Selective Sphingosine-1-Phosphate Receptor 1 Agonist

    PubMed Central

    Gao, Min; Liu, Yong; Xiao, Yang; Han, Gencheng; Jia, Liang; Wang, Liqiang; Lei, Tian; Huang, Yifei

    2014-01-01

    Corneal transplantation is the most used therapy for eye disorders. Although the cornea is somewhat an immune privileged organ, immune rejection is still the major problem that reduces the success rate. Therefore, effective chemical drugs that regulate immunoreactions are needed to improve the outcome of corneal transplantations. Here, a sphingosine-1-phosphate receptor 1 (S1P1) selective agonist was systematically evaluated in mouse allogeneic corneal transplantation and compared with the commonly used immunosuppressive agents. Compared with CsA and the non-selective sphingosine 1-phosphate (S1P) receptor agonist FTY720, the S1P1 selective agonist can prolong the survival corneal transplantation for more than 30 days with a low immune response. More importantly, the optimal dose of the S1P1 selective agonist was much less than non-selective S1P receptor agonist FTY720, which would reduce the dose-dependent toxicity in drug application. Then we analyzed the mechanisms of the selected S1P1 selective agonist on the immunosuppression. The results shown that the S1P1 selective agonist could regulate the distribution of the immune cells with less CD4+ T cells and enhanced Treg cells in the allograft, moreover the expression of anti-inflammatory cytokines TGF-β1 and IL-10 unregulated which can reduce the immunoreactions. These findings suggest that S1P1 selective agonist may be a more appropriate immunosuppressive compound to effectively prolong mouse allogeneic corneal grafts survival. PMID:25216235

  15. Conformationally constrained farnesoid X receptor (FXR) agonists: Naphthoic acid-based analogs of GW 4064.

    PubMed

    Akwabi-Ameyaw, Adwoa; Bass, Jonathan Y; Caldwell, Richard D; Caravella, Justin A; Chen, Lihong; Creech, Katrina L; Deaton, David N; Jones, Stacey A; Kaldor, Istvan; Liu, Yaping; Madauss, Kevin P; Marr, Harry B; McFadyen, Robert B; Miller, Aaron B; Iii, Frank Navas; Parks, Derek J; Spearing, Paul K; Todd, Dan; Williams, Shawn P; Wisely, G Bruce

    2008-08-01

    Starting from the known FXR agonist GW 4064 1a, a series of stilbene replacements were prepared. The 6-substituted 1-naphthoic acid 1b was an equipotent FXR agonist with improved developability parameters relative to 1a. Analog 1b also reduced the severity of cholestasis in the ANIT acute cholestatic rat model.

  16. Agonist-induced platelet procoagulant activity requires shear and a Rac1-dependent signaling mechanism

    PubMed Central

    Delaney, Michael Keegan; Liu, Junling; Kim, Kyungho; Shen, Bo; Stojanovic-Terpo, Aleksandra; Zheng, Yi; Cho, Jaehyung

    2014-01-01

    Activated platelets facilitate blood coagulation by exposing phosphatidylserine (PS) and releasing microvesicles (MVs). However, the potent physiological agonists thrombin and collagen poorly induce PS exposure when a single agonist is used. To obtain a greater procoagulant response, thrombin is commonly used in combination with glycoprotein VI agonists. However, even under these conditions, only a percentage of platelets express procoagulant activity. To date, it remains unclear why platelets poorly expose PS even when stimulated with multiple agonists and what the signaling pathways are of soluble agonist-induced platelet procoagulant activity. Here we show that physiological levels of shear present in blood significantly enhance agonist-induced platelet PS exposure and MV release, enabling low doses of a single agonist to induce full-scale platelet procoagulant activity. PS exposed on the platelet surface was immediately released as MVs, revealing a tight coupling between the 2 processes under shear. Using platelet-specific Rac1−/− mice, we discovered that Rac1 plays a common role in mediating the low-dose agonist-induced procoagulant response independent of platelet aggregation, secretion, and the apoptosis pathway. Platelet-specific Rac1 function was not only important for coagulation in vitro but also for fibrin accumulation in vivo following laser-induced arteriolar injury. PMID:25079357

  17. TSH and Thyrotropic Agonists: Key Actors in Thyroid Homeostasis

    PubMed Central

    Dietrich, Johannes W.; Landgrafe, Gabi; Fotiadou, Elisavet H.

    2012-01-01

    This paper provides the reader with an overview of our current knowledge of hypothalamic-pituitary-thyroid feedback from a cybernetic standpoint. Over the past decades we have gained a plethora of information from biochemical, clinical, and epidemiological investigation, especially on the role of TSH and other thyrotropic agonists as critical components of this complex relationship. Integrating these data into a systems perspective delivers new insights into static and dynamic behaviour of thyroid homeostasis. Explicit usage of this information with mathematical methods promises to deliver a better understanding of thyrotropic feedback control and new options for personalised diagnosis of thyroid dysfunction and targeted therapy, also by permitting a new perspective on the conundrum of the TSH reference range. PMID:23365787

  18. Proopiomelanocortin Deficiency Treated with a Melanocortin-4 Receptor Agonist.

    PubMed

    Kühnen, Peter; Clément, Karine; Wiegand, Susanna; Blankenstein, Oliver; Gottesdiener, Keith; Martini, Lea L; Mai, Knut; Blume-Peytavi, Ulrike; Grüters, Annette; Krude, Heiko

    2016-07-21

    Patients with rare defects in the gene encoding proopiomelanocortin (POMC) have extreme early-onset obesity, hyperphagia, hypopigmentation, and hypocortisolism, resulting from the lack of the proopiomelanocortin-derived peptides melanocyte-stimulating hormone and corticotropin. In such patients, adrenal insufficiency must be treated with hydrocortisone early in life. No effective pharmacologic treatments have been available for the hyperphagia and obesity that characterize the condition. In this investigator-initiated, open-label study, two patients with proopiomelanocortin deficiency were treated with setmelanotide, a new melanocortin-4 receptor agonist. The patients had a sustainable reduction in hunger and substantial weight loss (51.0 kg after 42 weeks in Patient 1 and 20.5 kg after 12 weeks in Patient 2). PMID:27468060

  19. [Safety and tolerability of GLP-1 receptor agonists].

    PubMed

    Soldevila, Berta; Puig-Domingo, Manel

    2014-01-01

    Glucagon-like peptide-1 receptor agonists (GLP-1ra) are a new group of drugs with a glucose-lowering action due to their incretin effect. The GLP-1 receptor is expressed in various human tissues, which could be related to the pleiotropic effects of human GLP-1, as well as to the adverse effects described in patients treated with GLP-1ra. The risk of hypoglycaemia is low, which is one of the main considerations in the safety of this family of compounds and is also important to patients with diabetes. The most frequent adverse effect is nausea, which usually occurs at the start of treatment and is transient in 20-60% of affected patients. This article also reviews the information available on antibody formation, the potential effect on the thyroid gland, and the controversial association between this group of drugs with pancreatitis and cancer.

  20. [Safety and tolerability of GLP-1 receptor agonists].

    PubMed

    Soldevila, Berta; Puig-Domingo, Manel

    2014-09-01

    Glucagon-like peptide-1 receptor agonists (GLP-1ra) are a new group of drugs with a glucose-lowering action due to their incretin effect. The GLP-1 receptor is expressed in various human tissues, which could be related to the pleiotropic effects of human GLP-1, as well as to the adverse effects described in patients treated with GLP-1ra. The risk of hypoglycaemia is low, which is one of the main considerations in the safety of this family of compounds and is also important to patients with diabetes. The most frequent adverse effect is nausea, which usually occurs at the start of treatment and is transient in 20-60% of affected patients. This article also reviews the information available on antibody formation, the potential effect on the thyroid gland, and the controversial association between this group of drugs with pancreatitis and cancer.

  1. Locomotion induced by ventral tegmental microinjections of a nicotinic agonist.

    PubMed

    Museo, E; Wise, R A

    1990-03-01

    Bilateral microinjections of the nicotinic agonist cytisine (0.1, 1 or 10 nanomoles per side) into the ventral tegmental area increased locomotor activity. This increase in locomotion was antagonized by mecamylamine (2 mg/kg, IP), a nicotinic antagonist that readily crosses the blood-brain barrier, and by pimozide (0.3 mg/kg, IP), a central dopaminergic antagonist. Hexamethonium (2 mg/kg, IP), a nicotinic antagonist that, unlike mecamylamine, does not cross the blood-brain barrier, had no effect; this suggests that mecamylamine's attenuation of cytisine-induced locomotor activity resulted from a blockade of central and not peripheral nicotinic receptors. The data support the notion that nicotinic and dopaminergic substrates interact at the level of the VTA to produce increases in locomotor activity.

  2. The GLP-1 agonist, liraglutide, as a pharmacotherapy for obesity.

    PubMed

    Crane, James; McGowan, Barbara

    2016-03-01

    There is a global obesity epidemic that will continue to be a financial burden on healthcare systems around the world. Tackling obesity through diet and exercise should always be the first intervention, but this has not proved to be effective for a large number of patients. Pharmacotherapeutic options have been limited and many previously available drugs have been withdrawn due to safety concerns. Currently, only bariatric surgery has the capability to induce both substantial and durable weight loss. This article briefly reviews the history of pharmacotherapy for obesity before focusing on the clinical trial evidence for the use of the GLP-1 agonist liraglutide as a weight loss agent and comparing its efficacy with other emerging drug therapies for obesity. PMID:26977279

  3. The GLP-1 agonist, liraglutide, as a pharmacotherapy for obesity

    PubMed Central

    Crane, James; McGowan, Barbara

    2015-01-01

    There is a global obesity epidemic that will continue to be a financial burden on healthcare systems around the world. Tackling obesity through diet and exercise should always be the first intervention, but this has not proved to be effective for a large number of patients. Pharmacotherapeutic options have been limited and many previously available drugs have been withdrawn due to safety concerns. Currently, only bariatric surgery has the capability to induce both substantial and durable weight loss. This article briefly reviews the history of pharmacotherapy for obesity before focusing on the clinical trial evidence for the use of the GLP-1 agonist liraglutide as a weight loss agent and comparing its efficacy with other emerging drug therapies for obesity. PMID:26977279

  4. Effects of dopamine agonists on hypothalamic defensive attack in cats.

    PubMed

    Maeda, H; Sato, T; Maki, S

    1985-07-01

    The effects of methamphetamine (MAT) and apomorphine (APO), dopamine agonists, were studied in 16 cats to evaluate their effects on threshold for defensive attack behavior elicited by electrical stimulation of the ventromedial hypothalamic nucleus (VMH). Directed attack and hissing were selected from elementary responses as constituting a defensive attack. Hissing threshold was measured in two situations, one with human provocation and the other without provocation. MAT administered systemically lowered the thresholds for all three types of responses in a dose-related manner (0.5, 1.0, and 3.0 mg/kg). The effects of 1.0 mg/kg of APO were almost identical to those observed with 0.5 or 1.0 mg/kg of MAT. These results suggest that MAT-induced aggressive behavior may be mediated by a dopamine-induced increase in the excitability of the VMH. PMID:4059404

  5. Antiinfective applications of toll-like receptor 9 agonists.

    PubMed

    Krieg, Arthur M

    2007-07-01

    The innate immune system detects pathogens by the presence of highly conserved pathogen-expressed molecules, which trigger host immune defenses. Toll-like receptor (TLR) 9 detects unmethylated CpG dinucleotides in bacterial or viral DNA, and can be stimulated for therapeutic applications with synthetic oligodeoxynucleotides containing immune stimulatory "CpG motifs." TLR9 activation induces both innate and adaptive immunity. The TLR9-induced innate immune activation can be applied in the prevention or treatment of infectious diseases, and the adaptive immune-enhancing effects can be harnessed for improving vaccines. This article highlights the current understanding of the mechanism of action of CpG oligodeoxynucleotides, and provides an overview of the preclinical data and early human clinical trial results, applying these TLR9 agonists in the field of infectious diseases. PMID:17607015

  6. Could Dopamine Agonists Aid in Drug Development for Anorexia Nervosa?

    PubMed Central

    Frank, Guido K. W.

    2014-01-01

    Anorexia nervosa is a severe psychiatric disorder most commonly starting during the teenage-years and associated with food refusal and low body weight. Typically there is a loss of menses, intense fear of gaining weight, and an often delusional quality of altered body perception. Anorexia nervosa is also associated with a pattern of high cognitive rigidity, which may contribute to treatment resistance and relapse. The complex interplay of state and trait biological, psychological, and social factors has complicated identifying neurobiological mechanisms that contribute to the illness. The dopamine D1 and D2 neurotransmitter receptors are involved in motivational aspects of food approach, fear extinction, and cognitive flexibility. They could therefore be important targets to improve core and associated behaviors in anorexia nervosa. Treatment with dopamine antagonists has shown little benefit, and it is possible that antagonists over time increase an already hypersensitive dopamine pathway activity in anorexia nervosa. On the contrary, application of dopamine receptor agonists could reduce circuit responsiveness, facilitate fear extinction, and improve cognitive flexibility in anorexia nervosa, as they may be particularly effective during underweight and low gonadal hormone states. This article provides evidence that the dopamine receptor system could be a key factor in the pathophysiology of anorexia nervosa and dopamine agonists could be helpful in reducing core symptoms of the disorder. This review is a theoretical approach that primarily focuses on dopamine receptor function as this system has been mechanistically better described than other neurotransmitters that are altered in anorexia nervosa. However, those proposed dopamine mechanisms in anorexia nervosa also warrant further study with respect to their interaction with other neurotransmitter systems, such as serotonin pathways. PMID:25988121

  7. Asimadoline, a κ-Opioid Agonist, and Visceral Sensation

    PubMed Central

    Camilleri, Michael

    2009-01-01

    SUMMARY Asimadoline is a potent κ-opioid receptor agonist with a diaryl acetamide structure. It has high affinity for the κ receptor, with IC50 of 5.6 nM (guinea pig) and 1.2 nM (human recombinant), and high selectively with κ: μ: δ binding ratios of 1:501:498 in human recombinant receptors. It acts as a complete agonist in in vitro assay. Asimadoline reduced sensation in response to colonic distension at subnoxious pressures in healthy volunteers and in IBS patients without alteration of colonic compliance. Asimadoline reduced satiation and enhanced the postprandial gastric volume (in female volunteers). However, there were no significant effects on gastrointestinal transit, colonic compliance, fasting or postprandial colonic tone. In a clinical trial in 40 patients with functional dyspepsia (Rome II), asimadoline did not significantly alter satiation or symptoms over 8 weeks. However, asimadoline, 0.5 mg, significantly decreased satiation in patients with higher postprandial fullness scores, and daily postprandial fullness severity (over 8 weeks); the asimadoline 1.0 mg group was borderline significant. In a clinical trial in patients with IBS, average pain 2 hours post-on-demand treatment with asimadoline was not significantly reduced. Post-hoc analyses suggest asimadoline was effective in mixed IBS. In a 12-week study in 596 patients, chronic treatment with asimadoline, 0.5 mg and 1.0 mg, was associated with adequate relief of pain and discomfort, improvement in pain score and number of pain free days in patients with IBS-D. The 1.0 mg dose was also efficacious in IBS-alternating. There were also weeks with significant reduction in bowel frequency and urgency. Asimadoline has been well tolerated in human trials to date. PMID:18715494

  8. Recent advances in the development of farnesoid X receptor agonists

    PubMed Central

    Carey, Elizabeth J.; Lindor, Keith D.

    2015-01-01

    Farnesoid X receptors (FXRs) are nuclear hormone receptors expressed in high amounts in body tissues that participate in bilirubin metabolism including the liver, intestines, and kidneys. Bile acids (BAs) are the natural ligands of the FXRs. FXRs regulate the expression of the gene encoding for cholesterol 7 alpha-hydroxylase, which is the rate-limiting enzyme in BA synthesis. In addition, FXRs play a critical role in carbohydrate and lipid metabolism and regulation of insulin sensitivity. FXRs also modulate live growth and regeneration during liver injury. Preclinical studies have shown that FXR activation protects against cholestasis-induced liver injury. Moreover, FXR activation protects against fatty liver injury in animal models of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH), and improved hyperlipidemia, glucose intolerance, and insulin sensitivity. Obeticholic acid (OCA), a 6α-ethyl derivative of the natural human BA chenodeoxycholic acid (CDCA) is the first-in-class selective FXR agonist that is ~100-fold more potent than CDCA. Preliminary human clinical trials have shown that OCA is safe and effective. In a phase II clinical trial, administration of OCA was well-tolerated, increased insulin sensitivity and reduced markers of liver inflammation and fibrosis in patients with type II diabetes mellitus and NAFLD. In two clinical trials of OCA in patients with primary biliary cirrhosis (PBC), a progressive cholestatic liver disease, OCA significantly reduced serum alkaline phosphatase (ALP) levels, an important disease marker that correlates well with clinical outcomes of patients with PBC. Together, these studies suggest that FXR agonists could potentially be used as therapeutic tools in patients suffering from nonalcoholic fatty and cholestatic liver diseases. Larger and Longer-term studies are currently ongoing. PMID:25705637

  9. Theory of partial agonist activity of steroid hormones

    PubMed Central

    Chow, Carson C.; Ong, Karen M.; Kagan, Benjamin; Simons, S. Stoney

    2015-01-01

    The different amounts of residual partial agonist activity (PAA) of antisteroids under assorted conditions have long been useful in clinical applications but remain largely unexplained. Not only does a given antagonist often afford unequal induction for multiple genes in the same cell but also the activity of the same antisteroid with the same gene changes with variations in concentration of numerous cofactors. Using glucocorticoid receptors as a model system, we have recently succeeded in constructing from first principles a theory that accurately describes how cofactors can modulate the ability of agonist steroids to regulate both gene induction and gene repression. We now extend this framework to the actions of antisteroids in gene induction. The theory shows why changes in PAA cannot be explained simply by differences in ligand affinity for receptor and requires action at a second step or site in the overall sequence of reactions. The theory also provides a method for locating the position of this second site, relative to a concentration limited step (CLS), which is a previously identified step in glucocorticoid-regulated transactivation that always occurs at the same position in the overall sequence of events of gene induction. Finally, the theory predicts that classes of antagonist ligands may be grouped on the basis of their maximal PAA with excess added cofactor and that the members of each class differ by how they act at the same step in the overall gene induction process. Thus, this theory now makes it possible to predict how different cofactors modulate antisteroid PAA, which should be invaluable in developing more selective antagonists. PMID:25984562

  10. Agonistic and antagonistic estrogens in licorice root (Glycyrrhiza glabra).

    PubMed

    Simons, Rudy; Vincken, Jean-Paul; Mol, Loes A M; The, Susan A M; Bovee, Toine F H; Luijendijk, Teus J C; Verbruggen, Marian A; Gruppen, Harry

    2011-07-01

    The roots of licorice (Glycyrrhiza glabra) are a rich source of flavonoids, in particular, prenylated flavonoids, such as the isoflavan glabridin and the isoflavene glabrene. Fractionation of an ethyl acetate extract from licorice root by centrifugal partitioning chromatography yielded 51 fractions, which were characterized by liquid chromatography-mass spectrometry and screened for activity in yeast estrogen bioassays. One third of the fractions displayed estrogenic activity towards either one or both estrogen receptors (ERs; ERα and ERβ). Glabrene-rich fractions displayed an estrogenic response, predominantly to the ERα. Surprisingly, glabridin did not exert agonistic activity to both ER subtypes. Several fractions displayed higher responses than the maximum response obtained with the reference compound, the natural hormone 17β-estradiol (E(2)). The estrogenic activities of all fractions, including this so-called superinduction, were clearly ER-mediated, as the estrogenic response was inhibited by 20-60% by known ER antagonists, and no activity was found in yeast cells that did not express the ERα or ERβ subtype. Prolonged exposure of the yeast to the estrogenic fractions that showed superinduction did, contrary to E(2), not result in a decrease of the fluorescent response. Therefore, the superinduction was most likely the result of stabilization of the ER, yeast-enhanced green fluorescent protein, or a combination of both. Most fractions displaying superinduction were rich in flavonoids with single prenylation. Glabridin displayed ERα-selective antagonism, similar to the ERα-selective antagonist RU 58668. Whereas glabridin was able to reduce the estrogenic response of E(2) by approximately 80% at 6 × 10(-6) M, glabrene-rich fractions only exhibited agonistic responses, preferentially on ERα.

  11. Agonist-specific behaviour of the intracellular Ca2+ response in rat hepatocytes.

    PubMed Central

    Chatton, J Y; Cao, Y; Stucki, J W

    1997-01-01

    A variety of agonists stimulate in hepatocytes a response that takes the shape of repetitive cytosolic free Ca2+ transients called Ca2+ oscillations. The shape of spikes and the pattern of oscillations in a given cell differ depending on the agonist of the phosphoinositide pathway that is applied. In this study, the response of individual rat hepatocytes to maximal stimulation by arginine vasopressin (AVP), phenylephrine and ADP was investigated by fluorescence microscopy and flash photolysis. Hepatocytes loaded with Ca2+-sensitive probes were stimulated with a first agonist to evoke a maximal response, and then a second agonist was added. When phenylephrine or ADP was used as the first agonist, AVP applied subsequently could elicit an additional response, which did not happen when AVP was first applied and phenylephrine or ADP was applied later. Cells microinjected with caged myo-inositol 1,4,5-trisphosphate (IP3) were challenged with the different agonists and, when a maximal response was obtained, photorelease of IP3 was triggered. Cells maximally stimulated with AVP did not respond to IP3 photorelease, whereas those stimulated with phenylephrine or ADP responded with a fast Ca2+ spike above the elevated steady-state level, which was followed by an undershoot. In contrast, with all three agonists, IP3 photorelease triggered at the top of an oscillatory Ca2+ transient was able to mobilize additional Ca2+. These experiments indicate that the differential response of cells to agonists is found not only during Ca2+ oscillations but also during maximal agonist stimulation and that potency and efficacy differences exist among agonists. PMID:9371717

  12. Dissociated sterol-based liver X receptor agonists as therapeutics for chronic inflammatory diseases.

    PubMed

    Yu, Shan; Li, Sijia; Henke, Adam; Muse, Evan D; Cheng, Bo; Welzel, Gustav; Chatterjee, Arnab K; Wang, Danling; Roland, Jason; Glass, Christopher K; Tremblay, Matthew

    2016-07-01

    Liver X receptor (LXR), a nuclear hormone receptor, is an essential regulator of immune responses. Activation of LXR-mediated transcription by synthetic agonists, such as T0901317 and GW3965, attenuates progression of inflammatory disease in animal models. However, the adverse effects of these conventional LXR agonists in elevating liver lipids have impeded exploitation of this intriguing mechanism for chronic therapy. Here, we explore the ability of a series of sterol-based LXR agonists to alleviate inflammatory conditions in mice without hepatotoxicity. We show that oral treatment with sterol-based LXR agonists in mice significantly reduces dextran sulfate sodium colitis-induced body weight loss, which is accompanied by reduced expression of inflammatory markers in the large intestine. The anti-inflammatory property of these agonists is recapitulated in vitro in mouse lamina propria mononuclear cells, human colonic epithelial cells, and human peripheral blood mononuclear cells. In addition, treatment with LXR agonists dramatically suppresses inflammatory cytokine expression in a model of traumatic brain injury. Importantly, in both disease models, the sterol-based agonists do not affect the liver, and the conventional agonist T0901317 results in significant liver lipid accumulation and injury. Overall, these results provide evidence for the development of sterol-based LXR agonists as novel therapeutics for chronic inflammatory diseases.-Yu, S., Li, S., Henke, A., Muse, E. D., Cheng, B., Welzel, G., Chatterjee, A. K., Wang, D., Roland, J., Glass, C. K., Tremblay, M. Dissociated sterol-based liver X receptor agonists as therapeutics for chronic inflammatory diseases. PMID:27025962

  13. Allosteric coupling from G protein to the agonist-binding pocket in GPCRs.

    PubMed

    DeVree, Brian T; Mahoney, Jacob P; Vélez-Ruiz, Gisselle A; Rasmussen, Soren G F; Kuszak, Adam J; Edwald, Elin; Fung, Juan-Jose; Manglik, Aashish; Masureel, Matthieu; Du, Yang; Matt, Rachel A; Pardon, Els; Steyaert, Jan; Kobilka, Brian K; Sunahara, Roger K

    2016-07-01

    G-protein-coupled receptors (GPCRs) remain the primary conduit by which cells detect environmental stimuli and communicate with each other. Upon activation by extracellular agonists, these seven-transmembrane-domain-containing receptors interact with heterotrimeric G proteins to regulate downstream second messenger and/or protein kinase cascades. Crystallographic evidence from a prototypic GPCR, the β2-adrenergic receptor (β2AR), in complex with its cognate G protein, Gs, has provided a model for how agonist binding promotes conformational changes that propagate through the GPCR and into the nucleotide-binding pocket of the G protein α-subunit to catalyse GDP release, the key step required for GTP binding and activation of G proteins. The structure also offers hints about how G-protein binding may, in turn, allosterically influence ligand binding. Here we provide functional evidence that G-protein coupling to the β2AR stabilizes a ‘closed’ receptor conformation characterized by restricted access to and egress from the hormone-binding site. Surprisingly, the effects of G protein on the hormone-binding site can be observed in the absence of a bound agonist, where G-protein coupling driven by basal receptor activity impedes the association of agonists, partial agonists, antagonists and inverse agonists. The ability of bound ligands to dissociate from the receptor is also hindered, providing a structural explanation for the G-protein-mediated enhancement of agonist affinity, which has been observed for many GPCR–G-protein pairs. Our data also indicate that, in contrast to agonist binding alone, coupling of a G protein in the absence of an agonist stabilizes large structural changes in a GPCR. The effects of nucleotide-free G protein on ligand-binding kinetics are shared by other members of the superfamily of GPCRs, suggesting that a common mechanism may underlie G-protein-mediated enhancement of agonist affinity. PMID:27362234

  14. 17β-Aminoestrogens induce guinea pig airway smooth muscle hyperresponsiveness through L-type Ca(2+) channels activation.

    PubMed

    Flores-Soto, Edgar; Martínez-Villa, Inocencio; Solís-Chagoyán, Héctor; Sommer, Bettina; Lemini, Cristina; Montaño, Luis M

    2015-09-01

    Therapy with estrogens is frequently used in menopausal women and as hormonal contraception. Because of its thrombotic effects, long term estrogen administration used in hormonal replacement therapy (HRT) and contraception could represent a health hazard. In this regard, 17β-aminoestrogens such as aminoestrol, butolame and pentolame have shown promising HRT potential, because they have a weak agonist estrogenic action and antithrombotic activity. Additionally, estrogens play a protective role in airway smooth muscle, but the effect of 17β-aminoestrogens on the airway smooth muscle has not been tested yet. In guinea pig tracheal smooth muscle pentolame and butolame induced hyperresponsiveness to histamine (His), carbachol (Cch) and KCl. Interestingly, aminoestrol did not show this effect at the highest concentration studied, it even lowered the contraction induced by Cch. The hyperresponsiveness induced by pentolame to His was abolished by nifedipine. In single tracheal myocytes, KCl induced an increment in the intracellular Ca(2+) concentration [Ca(2+)]i, pentolame also showed an increase in [Ca(2+)]i and the addition of KCl in the plateau of this rise further significantly augmented the [Ca(2+)]i response. Additionally, in patch clamp experiments pentolame increased the L-type Ca(2+) currents. Thus, 17β-aminoestrogens such as pentolame and butolame, but not aminoestrol, activate L-type Ca(2+) channel to induced hyperresponsiveness to Cch, His and KCl in guinea pig tracheal smooth muscle. Due to its lack of effect on airways and to its anticoagulant characteristics, aminoestrol seems to be the best alternative in the HRT among the 17β-aminoestrogens studied.

  15. Mimicking corticosterone's daily rhythm with specific receptor agonists: effects on food, water, and sodium intake.

    PubMed

    Devenport, L; Stith, R

    1992-06-01

    The endogenous pattern of type I and II corticosteroid receptor stimulation was systematically assembled from specific agonists in order to detect any unique receptor interactions in the control of ingestive behavior. The type II agonists dexamethasone (0, 5, or 25 micrograms/kg) or RU28362 (0, 5, or 25 micrograms/kg) were injected daily in the final hour of the light phase of the illumination cycle of adrenalectomized rats. This was carried out in the presence or absence of continuous aldosterone (type I agonist) infusion. Additional comparisons were made with sham-operated groups and animals receiving type II agonists by continuous infusion. Type II agonists increased the intake of 2% saline and the proportion of food taken at night, but had negligible effects on total food intake. Type II agonists did not interact with the type I agonist. Type II effects were greatly potentiated by continuous infusion, though administered at the same doses as acute injection. When the effects of type II receptor stimulation emerged, they always consisted of an exacerbation of the adrenalectomy syndrome, not a return to normal quantities or patterns. In contrast, type I receptor stimulation restored both the quantities and unique day-night patterns of saline, water, and food intake to values matching intact animals. The findings suggest that the behavioral significance of corticosterone's nocturnal peak of type II stimulation is small, and that its most important function may lie in the metabolic processes it instigates during its steady rise in the light phase.

  16. Gonadotropin-releasing hormone agonist use in men without a cancer registry diagnosis of prostate cancer

    PubMed Central

    Kuo, Yong-fang; Goodwin, James S; Shahinian, Vahakn B

    2008-01-01

    Background Use of gonadotropin-releasing hormone (GnRH) agonists has become popular for virtually all stages of prostate cancer. We hypothesized that some men receive these agents after only a limited work-up for their cancer. Such cases may be missed by tumor registries, leading to underestimates of the total extent of GnRH agonist use. Methods We used linked Surveillance, Epidemiology and End-Results (SEER)-Medicare data from 1993 through 2001 to identify GnRH agonist use in men with either a diagnosis of prostate cancer registered in SEER, or with a diagnosis of prostate cancer based only on Medicare claims (from the 5% control sample of Medicare beneficiaries residing in SEER areas without a registered diagnosis of cancer). The proportion of incident GnRH agonist users without a registry diagnosis of prostate cancer was calculated. Factors associated with lack of a registry diagnosis were examined in multivariable analyses. Results Of incident GnRH agonist users, 8.9% had no diagnosis of prostate cancer registered in SEER. In a multivariable logistic regression model, lack of a registry diagnosis of prostate cancer in GnRH agonist users was significantly more likely with increasing comorbidity, whereas it was less likely in men who had undergone either inpatient admission or procedures such as radical prostatectomy, prostate biopsy, or transurethral resection of the prostate. Conclusion Reliance solely on tumor registry data may underestimate the rate of GnRH agonist use in men with prostate cancer. PMID:18620606

  17. Luminescence Spectroscopy and Crystal Field Simulations of Europium Propylenediphosphonate EuH[O 3P(CH 2) 3PO 3] and Europium Glutarate [Eu(H 2O)] 2[O 2C(CH 2) 3CO 2] 3·4H 2O

    NASA Astrophysics Data System (ADS)

    Serpaggi, F.; Férey, G.; Antic-Fidancev, E.

    1999-12-01

    The results of investigations on the photoluminescence of two europium hybrid compounds, EuH[O3P(CH2)3PO3] (Eu[diph]) and [Eu(H2O)]2[O2C(CH2)3CO2]3·4H2O (Eu[glut]), are presented. In both compounds one local environment is found for the rare earth (Re) ion and the symmetry of the Re polyhedron is low (Cs) as evidenced by the Eu3+ luminescence studies. The electrostatic crystal field (cf) parameters of the 7F multiplet are obtained by the application of the phenomenological cf theory. The simulations using C2v symmetry for the rare earth ion give good agreement between the calculated and the experimental 7F0-4 energy level schemes. The observed optical data are discussed in relation to the crystal structure of the compounds.

  18. Use of gonadotrophin-releasing hormone agonists in controlled ovarian hyperstimulation for in vitro fertilization.

    PubMed

    Muasher, S J

    1992-01-01

    The aim of ovarian hyperstimulation for in vitro fertilization (IVF) is the recruitment of multiple fertilizable healthy oocytes. Transfer of multiple embryos yields a better success rate than single-embryo transfers. Moreover, cryopreservation of excess pre-embryos allows patients an added opportunity to achieve a pregnancy without undergoing a repeat stimulated cycle. In the last 4 years, gonadotrophin-releasing hormone (Gn-RH) agonists have been used widely as adjuncts to gonadotrophins for ovarian hyperstimulation. Advantages of Gn-RH agonist use include prevention of a premature luteinising hormone (LH) surge, suppression of endogenous basal LH levels and recruitment of a larger cohort of follicles. Gn-RH agonists can be used in a long (suppression) or a short (stimulatory, flare-up) protocol. In our clinic, the use of Gn-RH agonist suppression (starting in the mid-luteal phase) prior to ovarian hyperstimulation was demonstrated to be extremely beneficial in intermediate and high responder patients but not in low responders (defined endocrinologically as patients with a basal follicle-stimulating hormone [FSH]: LH ratio of 1:1 and a basal LH:FSH ratio of greater than or equal to 1.5, respectively). We have not been able to demonstrate any beneficial effects from the use of Gn-RH agonist suppression in low responder patients (defined endocrinologically as patients with a basal FSH greater than or equal to 15 mIU/ml). In such low responder patients, the use of a 'flare-up' Gn-RH agonist protocol (Gn-RH agonist starting on day 2 of the cycle, followed by gonadotrophins on day 4 of the cycle), taking advantage of the initial agonistic stimulatory effect of Gn-RH agonists on endogenous FSH and LH secretion, has provided significant improvements in stimulation characteristics and better pregnancy results. It should be emphasised that comparisons of results cannot be attempted due to the selective use of each protocol in different patient populations.

  19. Inhibition by TRPA1 agonists of compound action potentials in the frog sciatic nerve

    SciTech Connect

    Matsushita, Akitomo; Ohtsubo, Sena; Fujita, Tsugumi; Kumamoto, Eiichi

    2013-04-26

    Highlights: •TRPA1 agonists inhibited compound action potentials in frog sciatic nerves. •This inhibition was not mediated by TRPA1 channels. •This efficacy was comparable to those of lidocaine and cocaine. •We found for the first time an ability of TRPA1 agonists to inhibit nerve conduction. -- Abstract: Although TRPV1 and TRPM8 agonists (vanilloid capsaicin and menthol, respectively) at high concentrations inhibit action potential conduction, it remains to be unknown whether TRPA1 agonists have a similar action. The present study examined the actions of TRPA1 agonists, cinnamaldehyde (CA) and allyl isothiocyanate (AITC), which differ in chemical structure from each other, on compound action potentials (CAPs) recorded from the frog sciatic nerve by using the air-gap method. CA and AITC concentration-dependently reduced the peak amplitude of the CAP with the IC{sub 50} values of 1.2 and 1.5 mM, respectively; these activities were resistant to a non-selective TRP antagonist ruthenium red or a selective TRPA1 antagonist HC-030031. The CA and AITC actions were distinct in property; the latter but not former action was delayed in onset and partially reversible, and CA but not AITC increased thresholds to elicit CAPs. A CAP inhibition was seen by hydroxy-α-sanshool (by 60% at 0.05 mM), which activates both TRPA1 and TRPV1 channels, a non-vanilloid TRPV1 agonist piperine (by 20% at 0.07 mM) and tetrahydrolavandulol (where the six-membered ring of menthol is opened; IC{sub 50} = 0.38 mM). It is suggested that TRPA1 agonists as well as TRPV1 and TRPM8 agonists have an ability to inhibit nerve conduction without TRP activation, although their agonists are quite different in chemical structure from each other.

  20. Utility of gonadotropin-releasing hormone agonists in programs of ovarian hyperstimulation with intrauterine insemination.

    PubMed

    Gagliardi, C L

    1993-09-01

    The GnRH agonists have practical and theoretic advantages for adjunctive use in ovulation induction. The IVF cycles demonstrate a decrease in the cancellation rate, an increase in the ease of scheduling, and an increase in the number of oocytes obtained per retrieval when GnRH agonists are employed. Other advantages, such as an improvement in the fertilization and cleavage rate, an increased length of the luteal phase, and an increased pregnancy rate, are suggested but not universally accepted. The utility of adding GnRH agonists to human menopausal gonadotropin-intrauterine insemination cycles is similarly in dispute. Although controlled ovarian hyperstimulation with both human menopausal gonadotropins alone and in conjunction with GnRH agonists have produced pregnancies when coupled with intrauterine insemination, it was demonstrated that there was a significantly greater pregnancy rate per cycle with the use of a GnRH agonist in a recalcitrant infertile population. Others did not substantiate this improvement in pregnancy rate per cycle in their patient population of regularly ovulating women undergoing their first controlled ovarian stimulation cycle either with or without GnRH agonist therapy. This suggests that women with ovulatory dysfunction, and particularly women who previously have not responded to therapy with human menopausal gonadotropin therapy, will reap the most benefits from the addition of a GnRH agonist to their ovulation induction regimen. The addition of a GnRH agonist to controlled ovarian hyperstimulation is a highly effective method of inducing pregnancy in a recalcitrant infertile population. Patients who did not conceive with human menopausal gonadotropins-intrauterine insemination may conceive with GnRH agonist-human menopausal gonadotropins-intrauterine insemination therapy.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8403617

  1. Pairwise agonist scanning-flow cytometry (PAS-FC) measures inside-out signaling and patient-specific response to combinatorial platelet agonists.

    PubMed

    Jaeger, Daniel T L; Diamond, Scott L

    2013-05-01

    Understanding the response of cells to multiple stimuli is vital for predicting donor specific responses and better understanding the signaling pathways involved. This is of particular importance in platelets because exposure of phosphatidylserine (PS) occurs upon costimulation but not with a single agonist. Here, we describe a multiplexed pairwise agonist scanning-flow cytometry (PAS-FC) method of measuring platelet inside-out responses to all pairs of six platelet agonists (convulxin, SFLLRN, AYPGKF, ADP, U46619, and PGE(2)) used at their EC(50) concentrations. These agonists allowed exploration of platelet signaling downstream of GPVI, PAR-1, PAR-4, P2Y(1), P2Y(12), TP, and IP receptors. The three-color flow cytometry method simultaneously measured integrin α(IIb)β(3) activation with PAC-1 antibody, P-selectin exposure (via α granule release) with anti-P-selectin, and PS exposure with annexin V. These responses were consistent across a healthy male donor pool. In duplicate measurements with each donor, 4 of the 10 donors had a sufficiently unique 45-parameter (15 pairs × 3 colors) phenotype to self-cluster (P < 0.001). This method has the potential for efficiently scanning for patient specific responses across a broad agonist-receptor space.

  2. Pairwise agonist scanning-flow cytometry (PAS-FC) measures inside-out signaling and patient-specific response to combinatorial platelet agonists.

    PubMed

    Jaeger, Daniel T L; Diamond, Scott L

    2013-05-01

    Understanding the response of cells to multiple stimuli is vital for predicting donor specific responses and better understanding the signaling pathways involved. This is of particular importance in platelets because exposure of phosphatidylserine (PS) occurs upon costimulation but not with a single agonist. Here, we describe a multiplexed pairwise agonist scanning-flow cytometry (PAS-FC) method of measuring platelet inside-out responses to all pairs of six platelet agonists (convulxin, SFLLRN, AYPGKF, ADP, U46619, and PGE(2)) used at their EC(50) concentrations. These agonists allowed exploration of platelet signaling downstream of GPVI, PAR-1, PAR-4, P2Y(1), P2Y(12), TP, and IP receptors. The three-color flow cytometry method simultaneously measured integrin α(IIb)β(3) activation with PAC-1 antibody, P-selectin exposure (via α granule release) with anti-P-selectin, and PS exposure with annexin V. These responses were consistent across a healthy male donor pool. In duplicate measurements with each donor, 4 of the 10 donors had a sufficiently unique 45-parameter (15 pairs × 3 colors) phenotype to self-cluster (P < 0.001). This method has the potential for efficiently scanning for patient specific responses across a broad agonist-receptor space. PMID:23662898

  3. Infrared absorption of 1-chloro-2-methyl-2-propyl [ṡC(CH3)2CH2Cl] and 2-chloro-2-methylpropyl [ṡCH2C(CH3)2Cl] radicals produced in the addition reactions of Cl with isobutene (i-C4H8) in solid para-hydrogen

    NASA Astrophysics Data System (ADS)

    Chou, Ching-Yin; Lee, Yuan-Pern

    2016-10-01

    The addition reactions of chlorine atom with isobutene (i-C4H8) in solid para-hydrogen (p-H2) were investigated with infrared (IR) absorption spectra. When a p-H2 matrix containing Cl2 and isobutene was irradiated with ultraviolet light at 365 nm, intense lines in a set at 534.5, 1001.0, 1212.9, 1366.0, 2961.6, and 2934.7 cm-1, and several weaker others due to the 1-chloro-2-methyl-2-propyl radical, ṡC(CH3)2CH2Cl, and those in a second set including intense ones at 642.7, 799.2, 1098.2, 1371.8, and 3027.3 cm-1 due to the 2-chloro-2-methylpropyl radical, ṡCH2C(CH3)2Cl, appeared; the ratio of ṡC(CH3)2CH2Cl to ṡCH2C(CH3)2Cl was approximately (3 ± 1):1. The observed wavenumbers and relative intensities agree with the vibrational wavenumbers and IR intensities predicted with the B3PW91/aug-cc-pVTZ method. That the Cl atom adds to both carbons of the C=C bond of isobutene with the terminal site slightly favored is consistent with the energies of products predicted theoretically, but is in contrast to the reaction of Cl + propene in solid p-H2 in which the addition of Cl to mainly the central C atom was previously reported. The role of the p-H2 matrix in affecting the reaction paths is discussed. Absorption lines of the complex i-C4H8ṡCl2 and the dichloro-product anti-1,2-dichloro-2-methylpropane, a-CH2ClCCl(CH3)2, are also characterized.

  4. Agonist/antagonist modulation in a series of 2-aryl benzimidazole H4 receptor ligands.

    PubMed

    Savall, Brad M; Edwards, James P; Venable, Jennifer D; Buzard, Daniel J; Thurmond, Robin; Hack, Michael; McGovern, Patricia

    2010-06-01

    The present work details the transformation of a series of human histamine H(4) agonists into potent functional antagonists. Replacement of the aminopyrrolidine diamine functionality with a 5,6-fused pyrrolopiperidine ring system led to an antagonist. The dissection of this fused diamine led to the eventual replacement with heterocycles. The incorporation of histamine as the terminal amine led to a very potent and selective histamine H(4) agonist; whereas incorporation of the constrained histamine analog, spinacamine, modulated the functional activity to give a partial agonist. In two separate series, we demonstrate that constraining the terminal amino portion modulated the spectrum of functional activity of histamine H(4) ligands.

  5. Agonist-Specific Recruitment of Arrestin Isoforms Differentially Modify Delta Opioid Receptor Function

    PubMed Central

    Perroy, Julie; Walwyn, Wendy M.; Smith, Monique L.; Vicente-Sanchez, Ana; Segura, Laura; Bana, Alia; Kieffer, Brigitte L.; Evans, Christopher J.

    2016-01-01

    Ligand-specific recruitment of arrestins facilitates functional selectivity of G-protein-coupled receptor signaling. Here, we describe agonist-selective recruitment of different arrestin isoforms to the delta opioid receptor in mice. A high-internalizing delta opioid receptor agonist (SNC80) preferentially recruited arrestin 2 and, in arrestin 2 knock-outs (KOs), we observed a significant increase in the potency of SNC80 to inhibit mechanical hyperalgesia and decreased acute tolerance. In contrast, the low-internalizing delta agonists (ARM390, JNJ20788560) preferentially recruited arrestin 3 with unaltered behavioral effects in arrestin 2 KOs. Surprisingly, arrestin 3 KO revealed an acute tolerance to these low-internalizing agonists, an effect never observed in wild-type animals. Furthermore, we examined delta opioid receptor–Ca2+ channel coupling in dorsal root ganglia desensitized by ARM390 and the rate of resensitization was correspondingly decreased in arrestin 3 KOs. Live-cell imaging in HEK293 cells revealed that delta opioid receptors are in pre-engaged complexes with arrestin 3 at the cell membrane and that ARM390 strengthens this membrane interaction. The disruption of these complexes in arrestin 3 KOs likely accounts for the altered responses to low-internalizing agonists. Together, our results show agonist-selective recruitment of arrestin isoforms and reveal a novel endogenous role of arrestin 3 as a facilitator of resensitization and an inhibitor of tolerance mechanisms. SIGNIFICANCE STATEMENT Agonists that bind to the same receptor can produce highly distinct signaling events and arrestins are a major mediator of this ligand bias. Here, we demonstrate that delta opioid receptor agonists differentially recruit arrestin isoforms. We found that the high-internalizing agonist SNC80 preferentially recruits arrestin 2 and knock-out (KO) of this protein results in increased efficacy of SNC80. In contrast, low-internalizing agonists (ARM390 and JNJ20788560

  6. Synthesis and characterization of photoactivatable peptide agonists of the human thrombin receptor.

    PubMed

    Bischoff, R; Cordier, Y; Rasmussen, U B; Schlesinger, Y; Gachet, C; Jaquinod, M; Tripet, B; Chong, P C; Pavirani, A

    1994-08-01

    Chemical synthesis and biochemical analysis of modified agonist peptides of the human thrombin receptor derived from the sequence SFLLRNP containing photoactivatable azido groups and biotin for sensitive detection is described. Substitution of leucine in position three with p-azidophenylalanine and extension of the C-terminus with a KGGK spacer containing biotin covalently linked to the side chain of the C-terminal lysine residue resulted in an active receptor agonist as determined by intracellular Ca2+ mobilization in human erythroleukemia (HEL) cells. In contrast, substitution of phenylalanine in position two with p-azidophenylalanine reduced agonist activity significantly. PMID:8050586

  7. PPARα agonist, fenofibrate, ameliorates age-related renal injury.

    PubMed

    Kim, Eun Nim; Lim, Ji Hee; Kim, Min Young; Kim, Hyung Wook; Park, Cheol Whee; Chang, Yoon Sik; Choi, Bum Soon

    2016-08-01

    The kidney ages quickly compared with other organs. Expression of senescence markers reflects changes in the energy metabolism in the kidney. Two important issues in aging are mitochondrial dysfunction and oxidative stress. Peroxisome proliferator-activated receptor α (PPARα) is a member of the ligand-activated nuclear receptor superfamily. PPARα plays a major role as a transcription factor that regulates the expression of genes involved in various processes. In this study, 18-month-old male C57BL/6 mice were divided into two groups, the control group (n=7) and the fenofibrate-treated group (n=7) was fed the normal chow plus fenofibrate for 6months. The PPARα agonist, fenofibrate, improved renal function, proteinuria, histological change (glomerulosclerosis and tubular interstitial fibrosis), inflammation, and apoptosis in aging mice. This protective effect against age-related renal injury occurred through the activation of AMPK and SIRT1 signaling. The activation of AMPK and SIRT1 allowed for the concurrent deacetylation and phosphorylation of their target molecules and decreased the kidney's susceptibility to age-related changes. Activation of the AMPK-FOXO3a and AMPK-PGC-1α signaling pathways ameliorated oxidative stress and mitochondrial dysfunction. Our results suggest that activation of PPARα and AMPK-SIRT1 signaling may have protective effects against age-related renal injury. Pharmacological targeting of PPARα and AMPK-SIRT1 signaling molecules may prevent or attenuate age-related pathological changes in the kidney. PMID:27130813

  8. Object-horning in goitered gazelle: agonistic or marking behaviour?

    PubMed

    Blank, David; Yang, Weikang

    2014-03-01

    We studied object-horning behaviour in goitered gazelles in the natural, arid environment of Kazakhstan over a 6-year period. We found that object-horning was used by adult males mostly as a threat display during territorial conflicts. Therefore object-horning was observed most frequently in territorial single males during the rut in November-December. Object-horning, though, also had a marking effect, with the males' use of this behaviour leaving visible traces that advertized the location of preorbital and urination-defecation scent marks. Therefore, this pattern also was observed linked with preorbital marking and urination-defecation marking behaviours, especially during the rut. Goitered gazelle males chose the most abundant and eatable shrubs for object horning. In contrast to other gazelle species, object-horning in goitered gazelle was observed much more frequently and at the same rate as preorbital and urination-defecation scent markings. This, then, proved a more vigorous and aggressive level of rutting behaviour of the goitered gazelle compared to tropical gazelles, and most likely connected to the short rutting period in the studied species. We concluded, therefore, that object-horning was a manifold phenomenon that played a very important role in goitered gazelle agonistic displays, but without loosing the marking intention of this behaviour. PMID:24365541

  9. Therapeutic applications of TRAIL receptor agonists in cancer and beyond

    PubMed Central

    Amarante-Mendes, Gustavo P.; Griffith, Thomas S.

    2016-01-01

    TRAIL/Apo-2L is a member of the TNF superfamily first described as an apoptosis-inducing cytokine in 1995. Similar to TNF and Fas ligand, TRAIL induces apoptosis in caspase-dependent manner following TRAIL death receptor trimerization. Because tumor cells were shown to be particularly sensitive to this cytokine while normal cells/tissues proved to be resistant along with being able to synthesize and release TRAIL, it was rapidly appreciated that TRAIL likely served as one of our major physiologic weapons against cancer. In line with this, a number of research laboratories and pharmaceutical companies have attempted to exploit the ability of TRAIL to kill cancer cells by developing recombinant forms of TRAIL or TRAIL receptor agonists (e.g., receptor-specific mAb) for therapeutic purposes. In this review article we will describe the biochemical pathways used by TRAIL to induce different cell death programs. We will also summarize the clinical trials related to this pathway and discuss possible novel uses of TRAIL-related therapies. In recent years, the physiological importance of TRAIL has expanded beyond being a tumoricidal molecule to one critical for a number of clinical settings — ranging from infectious disease and autoimmunity to cardiovascular anomalies. We will also highlight some of these conditions where modulation of the TRAIL/TRAIL receptor system may be targeted in the future. PMID:26343199

  10. Glyoxalase 1 increases anxiety by reducing GABAA receptor agonist methylglyoxal

    PubMed Central

    Distler, Margaret G.; Plant, Leigh D.; Sokoloff, Greta; Hawk, Andrew J.; Aneas, Ivy; Wuenschell, Gerald E.; Termini, John; Meredith, Stephen C.; Nobrega, Marcelo A.; Palmer, Abraham A.

    2012-01-01

    Glyoxalase 1 (Glo1) expression has previously been associated with anxiety in mice; however, its role in anxiety is controversial, and the underlying mechanism is unknown. Here, we demonstrate that GLO1 increases anxiety by reducing levels of methylglyoxal (MG), a GABAA receptor agonist. Mice overexpressing Glo1 on a Tg bacterial artificial chromosome displayed increased anxiety-like behavior and reduced brain MG concentrations. Treatment with low doses of MG reduced anxiety-like behavior, while higher doses caused locomotor depression, ataxia, and hypothermia, which are characteristic effects of GABAA receptor activation. Consistent with these data, we found that physiological concentrations of MG selectively activated GABAA receptors in primary neurons. These data indicate that GLO1 increases anxiety by reducing levels of MG, thereby decreasing GABAA receptor activation. More broadly, our findings potentially link metabolic state, neuronal inhibitory tone, and behavior. Finally, we demonstrated that pharmacological inhibition of GLO1 reduced anxiety, suggesting that GLO1 is a possible target for the treatment of anxiety disorders. PMID:22585572

  11. Therapeutic applications of TRAIL receptor agonists in cancer and beyond.

    PubMed

    Amarante-Mendes, Gustavo P; Griffith, Thomas S

    2015-11-01

    TRAIL/Apo-2L is a member of the TNF superfamily first described as an apoptosis-inducing cytokine in 1995. Similar to TNF and Fas ligand, TRAIL induces apoptosis in caspase-dependent manner following TRAIL death receptor trimerization. Because tumor cells were shown to be particularly sensitive to this cytokine while normal cells/tissues proved to be resistant along with being able to synthesize and release TRAIL, it was rapidly appreciated that TRAIL likely served as one of our major physiologic weapons against cancer. In line with this, a number of research laboratories and pharmaceutical companies have attempted to exploit the ability of TRAIL to kill cancer cells by developing recombinant forms of TRAIL or TRAIL receptor agonists (e.g., receptor-specific mAb) for therapeutic purposes. In this review article we will describe the biochemical pathways used by TRAIL to induce different cell death programs. We will also summarize the clinical trials related to this pathway and discuss possible novel uses of TRAIL-related therapies. In recent years, the physiological importance of TRAIL has expanded beyond being a tumoricidal molecule to one critical for a number of clinical settings - ranging from infectious disease and autoimmunity to cardiovascular anomalies. We will also highlight some of these conditions where modulation of the TRAIL/TRAIL receptor system may be targeted in the future.

  12. Neurotensin agonist attenuates nicotine potentiation to cocaine sensitization.

    PubMed

    Fredrickson, Paul; Boules, Mona; Stennett, Bethany; Richelson, Elliott

    2014-03-01

    Tobacco usage typically precedes illicit drug use in adolescent and young adult populations. Several animal studies suggest nicotine increases the risk for subsequent cocaine abuse, and may be a negative prognostic factor for treatment of cocaine addiction; i.e., a "gateway drug". Neurotensin (NT) is a 13-amino acid neuropeptide that modulates dopamine, acetylcholine, glutamate, and GABA neurotransmission in brain reward pathways. NT69L, a NT(8-13) analog, blocks behavioral sensitization (an animal model for psychostimulant addiction) to nicotine, and nicotine self-administration in rats. The present study tested the effect of NT69L on the potentiating effects of nicotine on cocaine-induced locomotor sensitization. Male Wistar rats were injected daily for seven days with nicotine or saline (control) followed by four daily injections of cocaine. NT69L was administered 30 min prior to the last cocaine injection. Behavior was recorded with the use of activity chambers. Subchronic administration of nicotine enhanced cocaine-induced behavioral sensitization in Wistar rats, consistent with an hypothesized gateway effect. These behavioral effects of cocaine were attenuated by pretreatment with NT69L. The effect of the neurotensin agonist on cocaine sensitization in the nicotine treated group indicated a possible therapeutic effect for cocaine addiction, even in the presence of enhanced behavioral sensitization induced by nicotine. PMID:25379267

  13. Lipid metabolome-wide effects of the PPARgamma agonist rosiglitazone.

    PubMed

    Watkins, Steven M; Reifsnyder, Peter R; Pan, Huei-ju; German, J Bruce; Leiter, Edward H

    2002-11-01

    Successful therapy for chronic diseases must normalize a targeted aspect of metabolism without disrupting the regulation of other metabolic pathways essential for maintaining health. Use of a limited number of single molecule surrogates for disease, or biomarkers, to monitor the efficacy of a therapy may fail to predict undesirable side effects. In this study, a comprehensive metabolomic assessment of lipid metabolites was employed to determine the specific effects of the peroxisome proliferator-activated receptor gamma (PPARgamma) agonist rosiglitazone on structural lipid metabolism in a new mouse model of Type 2 diabetes. Dietary supplementation with rosiglitazone (200 mg/kg diet) suppressed Type 2 diabetes in obese (NZO x NON)F1 male mice, but chronic treatment markedly exacerbated hepatic steatosis. The metabolomic data revealed that rosiglitazone i) induced hypolipidemia (by dysregulating liver-plasma lipid exchange), ii) induced de novo fatty acid synthesis, iii) decreased the biosynthesis of lipids within the peroxisome, iv) substantially altered free fatty acid and cardiolipin metabolism in heart, and v) elicited an unusual accumulation of polyunsaturated fatty acids within adipose tissue. These observations suggest that the phenotypes induced by rosiglitazone are mediated by multiple tissue-specific metabolic variables. Because many of the effects of rosiglitazone on tissue metabolism were reflected in the plasma lipid metabolome, metabolomics has excellent potential for developing clinical assessments of metabolic response to drug therapy. PMID:12401879

  14. Agonist Derived Molecular Probes for A2A Adenosine Receptors

    PubMed Central

    Jacobson, Kenneth A.; Pannell, Lewis K.; Ji, Xiao-duo; Jarvis, Michael F.; Williams, Michael; Hutchison, Alan J.; Barrington, William W.; Stiles, Gary L.

    2011-01-01

    The adenosine agonist 2-(4-(2-carboxyethyl)phenylethylamino)-5′-N-ethylcarboxamidoadenosine (CGS21680) was recently reported to be selective for the A2A adenosine receptor subtype, which mediates its hypotensive action. To investigate structurelactivity relationships at a distal site, CGS21680 was derivatized using a functionalized congener approach. The carboxylic group of CGS21680 has been esterified to form a methyl ester, which was then treated with ethylenediamine to produce an amine congener. The amine congener was an intermediate for acylation reactions, in which the reactive acyl species contained a reported group, or the precursor for such. For radioiodination, derivatives of p-hydroxyphenylpropionic, 2-thiophenylacetic, and p-aminophenylacetic acids were prepared. The latter derivative (PAPA-APEC) was iodinated electrophilically using [125I]iodide resulting in a radioligand which was used for studies of competition of binding to striatal A, adenosine receptors in bovine brain. A biotin conjugate and an aryl sulfonate were at least 350-fold selective for A, receptors. For spectroscopic detection, a derivative of the stable free radical tetramethyl-1-piperidinyloxy (TEMPO) was prepared. For irreversible inhibition of receptors, meta- and para-phenylenediisothiocyanate groups were incorporated in the analogs. We have demonstrated that binding at A2A receptors is relatively insensitive to distal structural changes at the 2-position, and we report high affinity molecular probes for receptor characterization by radioactive, spectroscopic and affinity labelling methodology. PMID:2561548

  15. Agonists and Antagonists of TGF-β Family Ligands.

    PubMed

    Chang, Chenbei

    2016-08-01

    The discovery of the transforming growth factor β (TGF-β) family ligands and the realization that their bioactivities need to be tightly controlled temporally and spatially led to intensive research that has identified a multitude of extracellular modulators of TGF-β family ligands, uncovered their functions in developmental and pathophysiological processes, defined the mechanisms of their activities, and explored potential modulator-based therapeutic applications in treating human diseases. These studies revealed a diverse repertoire of extracellular and membrane-associated molecules that are capable of modulating TGF-β family signals via control of ligand availability, processing, ligand-receptor interaction, and receptor activation. These molecules include not only soluble ligand-binding proteins that were conventionally considered as agonists and antagonists of TGF-β family of growth factors, but also extracellular matrix (ECM) proteins and proteoglycans that can serve as "sink" and control storage and release of both the TGF-β family ligands and their regulators. This extensive network of soluble and ECM modulators helps to ensure dynamic and cell-specific control of TGF-β family signals. This article reviews our knowledge of extracellular modulation of TGF-β growth factors by diverse proteins and their molecular mechanisms to regulate TGF-β family signaling.

  16. Minireview: Challenges and opportunities in development of PPAR agonists.

    PubMed

    Wright, Matthew B; Bortolini, Michele; Tadayyon, Moh; Bopst, Martin

    2014-11-01

    The clinical impact of the fibrate and thiazolidinedione drugs on dyslipidemia and diabetes is driven mainly through activation of two transcription factors, peroxisome proliferator-activated receptors (PPAR)-α and PPAR-γ. However, substantial differences exist in the therapeutic and side-effect profiles of specific drugs. This has been attributed primarily to the complexity of drug-target complexes that involve many coregulatory proteins in the context of specific target gene promoters. Recent data have revealed that some PPAR ligands interact with other non-PPAR targets. Here we review concepts used to develop new agents that preferentially modulate transcriptional complex assembly, target more than one PPAR receptor simultaneously, or act as partial agonists. We highlight newly described on-target mechanisms of PPAR regulation including phosphorylation and nongenomic regulation. We briefly describe the recently discovered non-PPAR protein targets of thiazolidinediones, mitoNEET, and mTOT. Finally, we summarize the contributions of on- and off-target actions to select therapeutic and side effects of PPAR ligands including insulin sensitivity, cardiovascular actions, inflammation, and carcinogenicity. PMID:25148456

  17. The estrogen receptor antagonist ICI 182,780 can act both as an agonist and an inverse agonist when estrogen receptor α AF-2 is modified

    PubMed Central

    Movérare-Skrtic, Sofia; Börjesson, Anna E.; Farman, Helen H.; Sjögren, Klara; Windahl, Sara H.; Lagerquist, Marie K.; Andersson, Annica; Stubelius, Alexandra; Carlsten, Hans; Gustafsson, Jan-Åke; Ohlsson, Claes

    2014-01-01

    The bone-sparing effect of estrogen is primarily mediated via estrogen receptor (ER) α, which stimulates target gene transcription through two activation functions (AFs), AF-1 in the N-terminal and AF-2 in the ligand-binding domain. It was recently demonstrated that the ER antagonist ICI 182,780 (ICI) acts as an ER agonist in uterus of mice with mutations in the ERα AF-2. To evaluate the estrogen-like effects of ICI in different tissues, ovariectomized wild-type mice and mice with mutations in the ERα AF-2 (ERαAF-20) were treated with ICI, estradiol, or vehicle for 3 wk. Estradiol increased the trabecular and cortical bone mass as well as the uterine weight, whereas it reduced fat mass, thymus weight, and the growth plate height in wild-type but not in ERαAF-20 mice. Although ICI had no effect in wild-type mice, it exerted tissue-specific effects in ERαAF-20 mice. It acted as an ERα agonist on trabecular bone mass and uterine weight, whereas no effect was seen on cortical bone mass, fat mass, or thymus weight. Surprisingly, a pronounced inverse agonistic activity was seen on the growth plate height, resulting in enhanced longitudinal bone growth. In conclusion, ICI uses ERα AF-1 in a tissue-dependent manner in mice lacking ERαAF-2, resulting in no effect, agonistic activity, or inverse agonistic activity. We propose that ERα lacking AF-2 is constitutively active in the absence of ligand in the growth plate, enabling ICI to act as an inverse agonist. PMID:24395795

  18. The long-acting β2-adrenoceptor agonist, indacaterol, enhances glucocorticoid receptor-mediated transcription in human airway epithelial cells in a gene- and agonist-dependent manner

    PubMed Central

    Joshi, T; Johnson, M; Newton, R; Giembycz, M A

    2015-01-01

    Background and Purpose Inhaled glucocorticoid (ICS)/long-acting β2-adrenoceptor agonist (LABA) combination therapy is a recommended treatment option for patients with moderate/severe asthma in whom adequate control cannot be achieved by an ICS alone. Previously, we discovered that LABAs can augment dexamethasone-inducible gene expression and proposed that this effect may explain how these two drugs interact to deliver superior clinical benefit. Herein, we extended that observation by analysing, pharmacodynamically, the effect of the LABA, indacaterol, on glucocorticoid receptor (GR)-mediated gene transcription induced by seven ligands with intrinsic activity values that span the spectrum of full agonism to antagonism. Experimental Approach BEAS-2B human airway epithelial cells stably transfected with a 2× glucocorticoid response element luciferase reporter were used to model gene transcription together with an analysis of several glucocorticoid-inducible genes. Key Results Indacaterol augmented glucocorticoid-induced reporter activation in a manner that was positively related to the intrinsic activity of the GR agonist. This effect was demonstrated by an increase in response maxima without a change in GR agonist affinity or efficacy. Indacaterol also enhanced glucocorticoid-inducible gene expression. However, the magnitude of this effect was dependent on both the GR agonist and the gene of interest. Conclusions and Implications These data suggest that indacaterol activates a molecular rheostat, which increases the transcriptional competency of GR in an agonist- and gene-dependent manner without apparently changing the relationship between fractional GR occupancy and response. These findings provide a platform to rationally design ICS/LABA combination therapy that is based on the generation of agonist-dependent gene expression profiles in target and off-target tissues. PMID:25598440

  19. A study of [D-Pro2, D-Phe7, D-Trp9]-substance P and [D-Trp7,9]-substance P as tachykinin partial agonists in the rat colon.

    PubMed Central

    Bailey, S. J.; Jordan, C. C.

    1984-01-01

    Two substance P (SP) analogues, [D-Pro2, D-Phe7, D-Trp9]-SP (DPDPDT) and [D-Trp7,9]-SP (DT79), previously described as tachykinin antagonists, have been shown to contract the rat colon muscularis mucosae preparation. The maximum response exhibited by these analogues was about 30% that of the SP maximum, suggesting that they were acting as partial agonists relative to SP. The responses to DPDPDT were unaffected by pretreatment with mepyramine, methysergide or [Sar1, Ile5, Ala8]-angiotensin II, which abolished the responses to histamine, 5-hydroxytryptamine (5-HT) and angiotensin II, respectively. Methysergide also did not affect the responses to DT79; the other antagonists were not tested against this analogue. Indomethacin and cimetidine also had no inhibitory effect. Atropine (2 microM) was present in all experiments to prevent indirect muscarinic effects. Phenoxybenzamine did not affect the dose-response curves to SP, eledoisin-related peptide (ERP), kassinin, eledoisin or physalaemin, nor did it affect the responses to individual doses of DPDPDT or DT79. However, in the absence of atropine, it shifted the carbachol dose-response curve markedly to the right, and reduced its maximum. The tachykinin antagonist [D-Pro4, D-Trp7,9,10]-SP4-11 reduced the responses to individual matched doses of DPDPDT, DT79 and SP to the same degree, whilst leaving responses to 5-HT or angiotensin II unaffected. This suggested that DPDPDT and DT79 were acting at the same receptor as SP. The inhibitory effects of DPDPDT on responses to SP, ERP and kassinin, and that of DT79 on responses to SP, were analysed. All four combinations yielded data compatible with an interaction at only one receptor, although DPDPDT appeared slightly more potent at inhibiting responses to kassinin. The results are discussed in the light of the proposed existence of multiple tachykinin receptor subtypes. The possible influence of differential metabolism of tachykinin analogues is also considered. PMID:6203595

  20. Magnesium ions and opioid agonist activity in streptozotocin-induced hyperalgesia.

    PubMed

    Bujalska, Magdalena; Malinowska, Ewelina; Makulska-Nowak, Helena; Gumułka, Stanisław Witold

    2008-01-01

    Streptozotocin-induced hyperglycemia accompanied by a chronic decrease in the nociceptive threshold is considered a useful model of experimental hyperalgesia. We examined (1) the effect of the opioid receptor agonists and (2) the effect of the magnesium ions (Mg(2+)) on the antinociceptive action of opioid agonists in a diabetic neuropathic pain model. When administered alone, opioid agonists like morphine (5 mg/kg i.p.) and fentanyl (0.0625 mg/kg i.p.), as well as the partial agonist buprenorphine (0.075 mg/kg) had only little effect on streptozotocin-induced hyperalgesia. However, pretreatment with Mg(2+) at a dose of 40 mg magnesium sulfate/kg i.p. markedly enhanced the analgesic activity of all three investigated opioids. Practical aspects of co-administration of magnesium and opioids in diabetic neuropathy are discussed. PMID:18701828

  1. Increasing Potential Access to Opioid Agonist Treatment in U.S. Treatment Shortage Areas

    PubMed Central

    Dick, Andrew W.; Pacula, Rosalie Liccardo; Gordon, Adam J.; Sorbero, Mark; Burns, Rachel M.; Leslie, Douglas L.; Stein, Bradley D.

    2015-01-01

    Opioid use disorders are a significant public health problem, affecting over 2 million individuals in the US. Although opioid agonist treatment, predominantly offered in licensed methadone clinics, is both effective and cost-effective, many individuals do not receive it. Buprenorphine, approved in 2002 for prescription by waivered physicians, could improve opioid agonist treatment access for individuals unable or unwilling to receive methadone. We examine the extent to which the geographic distribution of waivered physicians has enhanced potential opioid agonist treatment access, particularly in non-metropolitan areas with fewer methadone clinics. We found that while the approximately 90% of counties classified as methadone clinic shortage areas remained constant, buprenorphine shortage areas fell from 99% of counties in 2002 to 51% in 2011, lowering the US population percentage residing in opioid treatment shortage counties to approximately 10%. The increase in buprenorphine-waivered physicians has dramatically increased potential access to opioid agonist treatment, especially in non-metropolitan counties. PMID:26056209

  2. Agonist binding to the NMDA receptor drives movement of its cytoplasmic domain without ion flow

    PubMed Central

    Dore, Kim; Aow, Jonathan; Malinow, Roberto

    2015-01-01

    The NMDA receptor (R) plays important roles in brain physiology and pathology as an ion channel. Here we examine the ion flow-independent coupling of agonist to the NMDAR cytoplasmic domain (cd). We measure FRET between fluorescently tagged cytoplasmic domains of GluN1 subunits of NMDARs expressed in neurons. Different neuronal compartments display varying levels of FRET, consistent with different NMDARcd conformations. Agonist binding drives a rapid and transient ion flow-independent reduction in FRET between GluN1 subunits within individual NMDARs. Intracellular infusion of an antibody targeting the GluN1 cytoplasmic domain blocks agonist-driven FRET changes in the absence of ion flow, supporting agonist-driven movement of the NMDARcd. These studies indicate that extracellular ligand binding to the NMDAR can transmit conformational information into the cell in the absence of ion flow. PMID:26553997

  3. Lepidozenolide from the liverwort Lepidozia fauriana acts as a farnesoid X receptor agonist.

    PubMed

    Lin, Hsiang-Ru

    2015-01-01

    Lepidozenolide is a sesquiterpenoid isolated from the liverwort Lepidozia fauriana and its possible bioactivity is unclear. The farnesoid X receptor (FXR) is a member of nuclear receptor superfamily that has been widely targeted for developing treatments for chronic liver disease and hyperglycemia. In this study, whether lepidozenolide may act as a FXR agonist was determined. Indeed, in mammalian one-hybrid and transient transfection reporter assays, lepidozenolide transactivated FXR to modulate promoter action including GAL4, CYP7A1, and PLTP promoters in a dose-dependent manner, while it exhibited slightly less agonistic activity than chenodeoxycholic acid, an endogenous FXR agonist. Through the molecular modeling docking studies lepidozenolide was shown to bind to FXR ligand binding pocket fairly well. All these results indicate that lepidozenolide acts as a FXR agonist. PMID:25315435

  4. Potent agonists of a hematopoietic stem cell cytokine receptor, c-Mpl.

    PubMed

    Tarasova, Anna; Haylock, David N; Meagher, Laurence; Be, Cheang Ly; White, Jacinta; Nilsson, Susan K; Andrade, Jessica; Cartledge, Kellie; Winkler, David A

    2013-05-01

    Several growth factors feature prominently in the control of hematopoiesis. Thrombopoietin, a class I hematopoietic cytokine, plays critical roles in regulating hematopoietic stem cell numbers and also stimulates the production and differentiation of megakaryocytes, the bone marrow cells that ultimately produce platelets. Thrombopoietin interacts with the c-Mpl cell-surface receptor. Recently, several peptide and small-molecule agonists and antagonists of c-Mpl have been reported. We conducted a bioinformatics and molecular modeling study aimed at understanding the agonist activities of peptides that bind to c-Mpl, and developed new potent peptide agonists with low nanomolar activity. These agonists also show very high activity in human CD34(+) primary cell cultures, and doubled the mean blood platelet counts when injected into mice.

  5. The pharmacokinetics of Toll-like receptor agonists and the impact on the immune system.

    PubMed

    Engel, Abbi L; Holt, Gregory E; Lu, Hailing

    2011-03-01

    Toll-like receptor (TLR) ligation activates both the innate and adaptive immune systems, and plays an important role in antiviral and anti-tumor immunity. Therefore, a significant amount of effort has been devoted to exploit the therapeutic potential of TLR agonists. Depending on the therapeutic purpose, either as adjuvants to vaccine, chemotherapy or standalone therapy, TLR agonists have been administered via different routes. Both preclinical and clinical studies have suggested that the route of administration has significant effects on pharmacokinetics, and that understanding these effects is critical to the success of TLR agonist drug development. This article will summarize the pharmacokinetics of TLR agonists with different administration routes, with an emphasis on clinical studies of TLR ligands in oncologic applications. PMID:21643519

  6. The pharmacokinetics of Toll-like receptor agonists and the impact on the immune system

    PubMed Central

    Engel, Abbi L; Holt, Gregory E; Lu, Hailing

    2011-01-01

    Toll-like receptor (TLR) ligation activates both the innate and adaptive immune systems, and plays an important role in antiviral and anti-tumor immunity. Therefore, a significant amount of effort has been devoted to exploit the therapeutic potential of TLR agonists. Depending on the therapeutic purpose, either as adjuvants to vaccine, chemotherapy or standalone therapy, TLR agonists have been administered via different routes. Both preclinical and clinical studies have suggested that the route of administration has significant effects on pharmacokinetics, and that understanding these effects is critical to the success of TLR agonist drug development. This article will summarize the pharmacokinetics of TLR agonists with different administration routes, with an emphasis on clinical studies of TLR ligands in oncologic applications. PMID:21643519

  7. Long-acting beta2-agonist in addition to tiotropium versus either tiotropium or long-acting beta2-agonist alone for chronic obstructive pulmonary disease

    PubMed Central

    Karner, Charlotta; Cates, Christopher J

    2014-01-01

    Background Long-acting bronchodilators comprising long-acting beta2-agonists and the anticholinergic agent tiotropium are commonly used for managing persistent symptoms of chronic obstructive pulmonary disease. Combining these treatments, which have different mechanisms of action, may be more effective than the individual components. However, the benefits and risks of combining tiotropium and long-acting beta2-agonists for the treatment of chronic obstructive pulmonary (COPD) disease are unclear. Objectives To assess the relative effects of treatment with tiotropium in addition to long-acting beta2-agonist compared to tiotropium or long-acting beta2-agonist alone in patients with chronic obstructive pulmonary disease. Search methods We searched the Cochrane Airways Group Specialised Register of trials and clinicaltrials.gov up to January 2012. Selection criteria We included parallel group, randomised controlled trials of three months or longer comparing treatment with tiotropium in addition to long-acting beta2-agonist against tiotropium or long-acting beta2-agonist alone for patients with chronic obstructive pulmonary disease. Data collection and analysis Two review authors independently assessed trials for inclusion and then extracted data on trial quality and the outcome results. We contacted study authors for additional information. We collected information on adverse effects from the trials. Main results Five trials were included in this review, mostly recruiting participants with moderate or severe chronic obstructive pulmonary disease. All of them compared tiotropium in addition to long-acting beta2-agonist to tiotropium alone, but only one trial additionally compared a combination of the two types of bronchodilator with long-acting beta2-agonist (formoterol) alone. Two studies used the long-acting beta2-agonist indacaterol, two used formoterol and one used salmeterol. Compared to tiotropium alone (3263 patients), treatment with tiotropium plus long

  8. Competitive molecular docking approach for predicting estrogen receptor subtype α agonists and antagonists

    PubMed Central

    2014-01-01

    Background Endocrine disrupting chemicals (EDCs) are exogenous compounds that interfere with the endocrine system of vertebrates, often through direct or indirect interactions with nuclear receptor proteins. Estrogen receptors (ERs) are particularly important protein targets and many EDCs are ER binders, capable of altering normal homeostatic transcription and signaling pathways. An estrogenic xenobiotic can bind ER as either an agonist or antagonist to increase or inhibit transcription, respectively. The receptor conformations in the complexes of ER bound with agonists and antagonists are different and dependent on interactions with co-regulator proteins that vary across tissue type. Assessment of chemical endocrine disruption potential depends not only on binding affinity to ERs, but also on changes that may alter the receptor conformation and its ability to subsequently bind DNA response elements and initiate transcription. Using both agonist and antagonist conformations of the ERα, we developed an in silico approach that can be used to differentiate agonist versus antagonist status of potential binders. Methods The approach combined separate molecular docking models for ER agonist and antagonist conformations. The ability of this approach to differentiate agonists and antagonists was first evaluated using true agonists and antagonists extracted from the crystal structures available in the protein data bank (PDB), and then further validated using a larger set of ligands from the literature. The usefulness of the approach was demonstrated with enrichment analysis in data sets with a large number of decoy ligands. Results The performance of individual agonist and antagonist docking models was found comparable to similar models in the literature. When combined in a competitive docking approach, they provided the ability to discriminate agonists from antagonists with good accuracy, as well as the ability to efficiently select true agonists and antagonists from

  9. Agonist-sensitive calcium pool in the pancreatic acinar cell. II. Characterization of reloading

    SciTech Connect

    Muallem, S.; Schoeffield, M.S.; Fimmel, C.J.; Pandol, S.J.

    1988-08-01

    45Ca2+ fluxes and free cytosolic Ca2+ measurements in guinea pig pancreatic acini indicated that after agonist stimulation and the release of Ca2+ from the agonist-sensitive pool at least part of the Ca2+ is extruded from the cell, resulting in 45Ca2+ efflux. In the continued presence of agonist, the pool remains permeable to Ca2+ but partially refills with Ca2+. This reloading is dependent on the concentration of extracellular Ca2+. In the absence of extracellular Ca2+, the pool is completely depleted of Ca2+. However, with increasing concentrations of CaCl2 in the incubation solution (from 0.5 to 2.0 mM) there is increasing repletion of the pool with Ca2+ during agonist stimulation. With termination of agonist stimulation, the Ca2+ permeability of the agonist-sensitive pool is rapidly reduced to that measured in the unstimulated cell. As a result, the Ca2+ incorporated into the pool during the stimulation period is rapidly trapped within the pool and exchanges poorly with medium Ca2+. Subsequently, the pool completely refills with Ca2+. The rate of Ca2+ reloading at the termination of agonist stimulation is slower than the conversion of the pool to the impermeable state. In incubation media containing 1.3 mM CaCl2, the half-time for reloading at the termination of stimulation is 5 min. These observations demonstrate the characteristics of Ca2+ reloading of the agonist-sensitive pool both during stimulation and at the termination of stimulation.

  10. Effects of oxytocin on serotonin 1B agonist-induced autism-like behavior in mice.

    PubMed

    Lawson, Sarah K; Gray, Andrew C; Woehrle, Nancy S

    2016-11-01

    Social impairments in autism remain poorly understood and without approved pharmacotherapies. Novel animals models are needed to elucidate mechanisms and evaluate novel treatments for the social deficits in autism. Recently, serotonin 1B receptor (5-HT1B) agonist challenge in mice was shown to induce autism-like behaviors including perseveration, reduced prepulse inhibition, and delayed alternation deficits. However, the effects of 5-HT1B agonists on autism-related social behaviors in mice remain unknown. Here, we examine the effects of 5-HT1B agonist challenge on sociability and preference for social novelty in mice. We also examine the effects of 5-HT1B agonist treatment on average rearing duration, a putative rodent measure of non-selective attention. Non-selective attention is an associated feature of autism that is also not well understood. We show that 5-HT1B receptor activation reduces sociability, preference for social novelty, and rearing in mice. In addition, we examine the ability of oxytocin, an off-label treatment for the social impairments in autism, to reverse 5-HT1B agonist-induced social and attention deficits in mice. We show that oxytocin restores social novelty preference in mice treated with a 5-HT1B agonist. We also show that oxytocin attenuates 5-HT1B agonist-induced sociability and rearing deficits in mice. Our results suggest that 5-HT1B agonist challenge provides a useful pharmacological mouse model for aspects of autism, and implicate 5-HT1B in autism social and attention deficits. Moreover, our findings suggest that oxytocin may treat the social deficits in autism through a mechanism involving 5-HT1B.

  11. Discovery of Azetidinone Acids as Conformationally-Constrained Dual PPARalpha/gamma Agonists

    SciTech Connect

    Wang, W.; Devasthale, P; Farrelly, D; Gu, L; Harrity, T; Cap, M; Chu, C; Kunselman, L; Morgan, N; et. al.

    2008-01-01

    A novel class of azetidinone acid-derived dual PPAR{alpha}/{gamma} agonists has been synthesized for the treatment of diabetes and dyslipidemia. The preferred stereochemistry in this series for binding and functional agonist activity against both PPARa and PPAR? receptors was shown to be 3S,4S. Synthesis, in vitro and in vivo activities of compounds in this series are described. A high-yielding method for N-arylation of azetidinone esters is also described.

  12. Rational design of orally-active, pyrrolidine-based progesterone receptor partial agonists

    SciTech Connect

    Thompson, Scott K.; Washburn, David G.; Frazee, James S.; Madauss, Kevin P.; Hoang, Tram H.; Lapinski, Leahann; Grygielko, Eugene T.; Glace, Lindsay E.; Trizna, Walter; Williams, Shawn P.; Duraiswami, Chaya; Bray, Jeffrey D.; Laping, Nicholas J.

    2010-09-03

    Using the X-ray crystal structure of an amide-based progesterone receptor (PR) partial agonist bound to the PR ligand binding domain, a novel PR partial agonist class containing a pyrrolidine ring was designed. Members of this class of N-alkylpyrrolidines demonstrate potent and highly selective partial agonism of the progesterone receptor, and one of these analogs was shown to be efficacious upon oral dosing in the OVX rat model of estrogen opposition.

  13. Identification of Hydroxybenzoic Acids as Selective Lactate Receptor (GPR81) Agonists with Antilipolytic Effects.

    PubMed

    Dvorak, Curt A; Liu, Changlu; Shelton, Jonathan; Kuei, Chester; Sutton, Steven W; Lovenberg, Timothy W; Carruthers, Nicholas I

    2012-08-01

    Following the characterization of the lactate receptor (GPR81), a focused screening effort afforded 3-hydroxybenzoic acid 1 as a weak agonist of both GPR81 and GPR109a (niacin receptor). An examination of structurally similar arylhydroxy acids led to the identification of 3-chloro-5-hydroxybenzoic acid 2, a selective GPR81 agonist that exhibited favorable in vivo effects on lipolysis in a mouse model of obesity.

  14. Identification of Hydroxybenzoic Acids as Selective Lactate Receptor (GPR81) Agonists with Antilipolytic Effects

    PubMed Central

    2012-01-01

    Following the characterization of the lactate receptor (GPR81), a focused screening effort afforded 3-hydroxybenzoic acid 1 as a weak agonist of both GPR81 and GPR109a (niacin receptor). An examination of structurally similar arylhydroxy acids led to the identification of 3-chloro-5-hydroxybenzoic acid 2, a selective GPR81 agonist that exhibited favorable in vivo effects on lipolysis in a mouse model of obesity. PMID:24900524

  15. Identification of benzoxazole analogs as novel, S1P(3) sparing S1P(1) agonists.

    PubMed

    Deng, Guanghui; Meng, Qinghua; Liu, Qian; Xu, Xuesong; Xu, Qiongfeng; Ren, Feng; Guo, Taylor B; Lu, Hongtao; Xiang, Jia-Ning; Elliott, John D; Lin, Xichen

    2012-06-15

    A novel series of benzoxazole-derived S1P(1) agonists were designed based on scaffold hopping molecular design strategy combined with computational approaches. Extensive SAR studies led to the discovery of compound 17d as a selective S1P(1) agonist (over S1P(3)) with high CNS penetration and favorable DMPK properties. 17d also demonstrated in vivo pharmacological efficacy to reduce blood lymphocyte in mice after oral administration.

  16. SAR of psilocybin analogs: discovery of a selective 5-HT 2C agonist.

    PubMed

    Sard, Howard; Kumaran, Govindaraj; Morency, Cynthia; Roth, Bryan L; Toth, Beth Ann; He, Ping; Shuster, Louis

    2005-10-15

    An SAR study of psilocybin and psilocin derivatives reveals that 1-methylpsilocin is a selective agonist at the h5-HT(2C) receptor. The corresponding phosphate derivative, 1-methylpsilocybin, shows efficacy in an animal model for obsessive-compulsive disorder, as does 4-fluoro-N,N-dimethyltryptamine. These results suggest a new area for development of novel 5-HT(2C) agonists with applications for drug discovery.

  17. The Good, the Bad, and the Ugly: Agonistic Behaviour in Juvenile Crocodilians

    PubMed Central

    Brien, Matthew L.; Lang, Jeffrey W.; Webb, Grahame J.; Stevenson, Colin; Christian, Keith A.

    2013-01-01

    We examined agonistic behaviour in seven species of hatchling and juvenile crocodilians held in small groups (N = 4) under similar laboratory conditions. Agonistic interactions occurred in all seven species, typically involved two individuals, were short in duration (5–15 seconds), and occurred between 1600–2200 h in open water. The nature and extent of agonistic interactions, the behaviours displayed, and the level of conspecific tolerance varied among species. Discrete postures, non-contact and contact movements are described. Three of these were species-specific: push downs by C. johnstoni; inflated tail sweeping by C. novaeguineae; and, side head striking combined with tail wagging by C. porosus. The two long-snouted species (C. johnstoni and G. gangeticus) avoided contact involving the head and often raised the head up out of the way during agonistic interactions. Several behaviours not associated with aggression are also described, including snout rubbing, raising the head up high while at rest, and the use of vocalizations. The two most aggressive species (C. porosus, C. novaeguineae) appeared to form dominance hierarchies, whereas the less aggressive species did not. Interspecific differences in agonistic behaviour may reflect evolutionary divergence associated with morphology, ecology, general life history and responses to interspecific conflict in areas where multiple species have co-existed. Understanding species-specific traits in agonistic behaviour and social tolerance has implications for the controlled raising of different species of hatchlings for conservation, management or production purposes. PMID:24349018

  18. Scaffold-Based Pan-Agonist Design for the PPARα, PPARβ and PPARγ Receptors

    PubMed Central

    Xu, Wei-Ren; Wang, Run-Ling; Wang, Jing-Fang

    2012-01-01

    As important members of nuclear receptor superfamily, Peroxisome proliferator-activated receptors (PPAR) play essential roles in regulating cellular differentiation, development, metabolism, and tumorigenesis of higher organisms. The PPAR receptors have 3 identified subtypes: PPARα, PPARβ and PPARγ, all of which have been treated as attractive targets for developing drugs to treat type 2 diabetes. Due to the undesirable side-effects, many PPAR agonists including PPARα/γ and PPARβ/γ dual agonists are stopped by US FDA in the clinical trials. An alternative strategy is to design novel pan-agonist that can simultaneously activate PPARα, PPARβ and PPARγ. Under such an idea, in the current study we adopted the core hopping algorithm and glide docking procedure to generate 7 novel compounds based on a typical PPAR pan-agonist LY465608. It was observed by the docking procedures and molecular dynamics simulations that the compounds generated by the core hopping and glide docking not only possessed the similar functions as the original LY465608 compound to activate PPARα, PPARβ and PPARγ receptors, but also had more favorable conformation for binding to the PPAR receptors. The additional absorption, distribution, metabolism and excretion (ADME) predictions showed that the 7 compounds (especially Cpd#1) hold high potential to be novel lead compounds for the PPAR pan-agonist. Our findings can provide a new strategy or useful insights for designing the effective pan-agonists against the type 2 diabetes. PMID:23119024

  19. Scaffold-based pan-agonist design for the PPARα, PPARβ and PPARγ receptors.

    PubMed

    Zhang, Li-Song; Wang, Shu-Qing; Xu, Wei-Ren; Wang, Run-Ling; Wang, Jing-Fang

    2012-01-01

    As important members of nuclear receptor superfamily, Peroxisome proliferator-activated receptors (PPAR) play essential roles in regulating cellular differentiation, development, metabolism, and tumorigenesis of higher organisms. The PPAR receptors have 3 identified subtypes: PPARα, PPARβ and PPARγ, all of which have been treated as attractive targets for developing drugs to treat type 2 diabetes. Due to the undesirable side-effects, many PPAR agonists including PPARα/γ and PPARβ/γ dual agonists are stopped by US FDA in the clinical trials. An alternative strategy is to design novel pan-agonist that can simultaneously activate PPARα, PPARβ and PPARγ. Under such an idea, in the current study we adopted the core hopping algorithm and glide docking procedure to generate 7 novel compounds based on a typical PPAR pan-agonist LY465608. It was observed by the docking procedures and molecular dynamics simulations that the compounds generated by the core hopping and glide docking not only possessed the similar functions as the original LY465608 compound to activate PPARα, PPARβ and PPARγ receptors, but also had more favorable conformation for binding to the PPAR receptors. The additional absorption, distribution, metabolism and excretion (ADME) predictions showed that the 7 compounds (especially Cpd#1) hold high potential to be novel lead compounds for the PPAR pan-agonist. Our findings can provide a new strategy or useful insights for designing the effective pan-agonists against the type 2 diabetes. PMID:23119024

  20. How neighborhood disorder increases blood pressure in youth: agonistic striving and subordination

    PubMed Central

    Elder, Gavin J.; Smyth, Joshua M.

    2012-01-01

    Growing evidence links perceptions of neighborhood disorder to adverse health outcomes but little is known about psychological processes that may mediate this association. We tested the hypothesis that two psychological mechanisms—agonistic striving and subordination—mediate the link between perceived neighborhood disorder and hypertension risk in youth. Perceived neighborhood disorder, agonistic striving, subordination experiences, negative affect, obesity, and ambulatory blood pressure during daily activities (48 h) were assessed in a multiethnic sample of 167 low- to middle-income urban adolescents. Path analyses revealed that agonistic striving, subordination, and obesity each independently mediated the association between neighborhood disorder and blood pressure; these variables accounted for 73 % of the shared variance, 42 % of which was explained by agonistic striving. The direct relationship between perceived neighborhood disorder and blood pressure was no longer significant in the presence of these mediators. Negative affect was associated with neighborhood disorder and subordination, but not blood pressure. Agonistic striving proved to be a significant and substantial mediator of the association between perceived neighborhood disorder, blood pressure, and future hypertension risk. New research should seek to clarify the processes by which stressful neighborhoods induce persistent agonistic motives and perceptions of subordination in adolescents. PMID:23229689

  1. Comparative Review of Approved Melatonin Agonists for the Treatment of Circadian Rhythm Sleep-Wake Disorders.

    PubMed

    Williams, Wilbur P Trey; McLin, Dewey E; Dressman, Marlene A; Neubauer, David N

    2016-09-01

    Circadian rhythm sleep-wake disorders (CRSWDs) are characterized by persistent or recurrent patterns of sleep disturbance related primarily to alterations of the circadian rhythm system or the misalignment between the endogenous circadian rhythm and exogenous factors that affect the timing or duration of sleep. These disorders collectively represent a significant unmet medical need, with a total prevalence in the millions, a substantial negative impact on quality of life, and a lack of studied treatments for most of these disorders. Activation of the endogenous melatonin receptors appears to play an important role in setting the circadian clock in the suprachiasmatic nucleus of the hypothalamus. Therefore, melatonin agonists, which may be able to shift and/or stabilize the circadian phase, have been identified as potential therapeutic candidates for the treatment of CRSWDs. Currently, only one melatonin receptor agonist, tasimelteon, is approved for the treatment of a CRSWD: non-24-hour sleep-wake disorder (or non-24). However, three additional commercially available melatonin receptor agonists-agomelatine, prolonged-release melatonin, and ramelteon-have been investigated for potential use for treatment of CRSWDs. Data indicate that these melatonin receptor agonists have distinct pharmacologic profiles that may help clarify their clinical use in CRSWDs. We review the pharmacokinetic and pharmacodynamic properties of these melatonin agonists and summarize their efficacy profiles when used for the treatment of CRSWDs. Further studies are needed to determine the therapeutic potential of these melatonin agonists for most CRSWDs.

  2. GLP-1 receptor agonists or DPP-4 inhibitors: how to guide the clinician?

    PubMed

    Scheen, André J

    2013-12-01

    Pharmacological treatment of type 2 diabetes has been enriched during recent years, with the launch of incretin therapies targeting glucagon-like peptide-1 (GLP-1). Such medications comprise either GLP-1 receptor agonists, with short (one or two daily injections: exenatide, liraglutide, lixisenatide) or long duration (one injection once weekly: extended-released exenatide, albiglutide, dulaglutide, taspoglutide); or oral compounds inhibiting dipeptidyl peptidase-4 (DPP-4), the enzyme that inactives GLP-1, also called gliptins (sitagliptin, vildagliptin, saxagliptin, linagliptin, alogliptin). Although both pharmacological approaches target GLP-1, important differences exist concerning the mode of administration (subcutaneous injection versus oral ingestion), the efficacy (better with GLP-1 agonists), the effects on body weight and systolic blood pressure (diminution with agonists versus neutrality with gliptins), the tolerance profile (nausea and possibly vomiting with agonists) and the cost (higher with GLP-1 receptor agonists). Both agents may exert favourable cardiovascular effects. Gliptins may represent a valuable alternative to a sulfonylurea or a glitazone after failure of monotherapy with metformin while GLP-1 receptor agonists may be considered as a good alternative to insulin (especially in obese patients) after failure of a dual oral therapy. However, this scheme is probably too restrictive and modalities of using incretins are numerous, in almost all stages of type 2 diabetes. Physicians may guide the pharmacological choice based on clinical characteristics, therapeutic goals and patient's preference.

  3. β-Adrenoreceptor agonists in the management of pain associated with renal colic: a systematic review

    PubMed Central

    Johnson, Graham David; Fakis, Apostolos; Surtees, Jane; Lennon, Robert Iain

    2016-01-01

    Objectives To determine whether β-adrenoreceptor agonists are effective analgesics for patients with renal colic through a systematic review of the literature. Setting Adult emergency departments or acute assessment units. Participants Human participants with proven or suspected renal colic. Interventions β-adrenoreceptor agonists. Outcome measures Primary: level of pain at 30 min following administration of the β-agonist. Secondary: level of pain at various time points following β-agonist administration; length of hospital stay; analgesic requirement; stone presence, size and position; degree of hydronephrosis. Results 256 records were screened and 4 identified for full-text review. No articles met the inclusion criteria. Conclusions and implications There is no evidence to support or refute the proposed use of β-agonists for analgesia in patients with renal colic. Given the biological plausibility and existing literature base, clinical trials investigating the use of β-adrenoreceptor agonists in the acute setting for treatment of the pain associated with renal colic are recommended. Trial registration number CRD42015016266. PMID:27324714

  4. Three-dimensional common-feature hypotheses for octopamine agonist 2-(arylimino)imidazolidines.

    PubMed

    Hirashima, Akinori; Morimoto, Masako; Kuwano, Eiichi; Taniguchi, Eiji; Eto, Morifusa

    2002-01-01

    Three-dimensional pharmacophore hypotheses were built from a set of 10 octopamine (OA) agonist 2-(Arylimino)imidazolidines (AIIs), 2-(Arylimino)thiazolidines (AITs) and 2-(Arylimino)oxazolidines (AIOs). Among the 10 common-featured models generated by program Catalyst/HipHop, a hypothesis including a ring aromatic (RA), a positive ionizable (PI) and three hydrophobic aliphatic (HpAl) features was considered to be important in evaluating the OA-agonist activity. Active OA agonist 2,6-Et2 AII mapped well onto all the RA, PI and HpAl features of the hypothesis. On the other hand, less active compounds were shown to be difficult to achieve the energetically favorable conformation which is found in the active molecules in order to fit the 3-D common-feature pharmacophore models. Taken together, 2,6-Et2-Ph and foramidine structures are important as OA agonists. The present studies on OA agonists demonstrate that a RA, a PI and three HpAl sites located on the molecule seem to be essential for OA-agonist activity. PMID:11738614

  5. Identification of metals from osteoblastic ST-2 cell supernatants as novel OGR1 agonists.

    PubMed

    Abe-Ohya, Rie; Ishikawa, Tomio; Shiozawa, Hideyuki; Suda, Koji; Nara, Futoshi

    2015-01-01

    Ovarian cancer G-protein-coupled receptor 1 (OGR1) is a G-protein-coupled receptor (GPCR), which has previously been identified as a receptor for protons. It has been reported in this and previous studies that OGR1 expression was markedly up-regulated during osteoclast differentiation. We predicted the possibility of other molecules activating OGR1 in neutral pH, and that osteoblasts might release OGR1 agonistic molecules and activate OGR1 expressed in osteoclasts such as RANKL. We screened for cell supernatants and organ extracts and discovered OGR1 agonistic activity in ST-2 osteoblastic cell supernatants and pancreatic tissues. Finally, we partially purified and identified essential metals, Fe, Zn, Co, Ni and Mn, as novel OGR1 agonists. These OGR1 agonistic metals induce intracellular Gq-coupled inositol phosphate signals in OGR1-expressing cells and primary osteoclasts through OGR1. We also confirmed that these OGR1 agonistic metals activated OGR1 through the same residues which act with protons. Here, we demonstrate that metals, Fe, Zn, Co, Ni and Mn are the novel OGR1 agonists, which can singly activate OGR1 in neutral pH.

  6. Functional assays to define agonists and antagonists of the sigma-2 receptor

    PubMed Central

    Zeng, Chenbo; Rothfuss, Justin M.; Zhang, Jun; Vangveravong, Suwanna; Chu, Wenhua; Li, Shihong; Tu, Zhude; Xu, Jinbin; Mach, Robert H.

    2014-01-01

    The sigma-2 receptor has been identified as a biomarker in proliferating tumors. Up to date there is no well-established functional assay for defining sigma-2 agonists and antagonists. Many sigma-2 ligands with diverse structures have been shown to induce cell death in a variety of cancer cells by triggering caspase-dependent and independent apoptosis. Therefore, in the current study, we used the cell viability assay and the caspase-3 activity assay to determine sigma-2 agonists and antagonists. Three classes of sigma-2 ligands developed in our laboratory were evaluated for their potency to induce cell death in two tumor cell lines, mouse breast cancer cell line EMT-6 and human melanoma cell line MDA-MB-435. The data showed that the EC50 values of the sigma-2 ligands using the cell viability assay ranged from 11.4 μM to >200 μM, which were comparable with the EC50 values obtained using the caspase-3 assay. Based on the cytotoxicity of a sigma-2 ligand relative to that of siramesine, a commonly accepted sigma-2 agonist, we have categorized our sigma-2 ligands into agonists, partial agonists, and antagonists. The establishment of functional assays for defining sigma-2 agonists and antagonists will facilitate functional characterization of sigma-2 receptor ligands and sigma-2 receptors. PMID:24333652

  7. Do inhaled beta(2)-agonists have an ergogenic potential in non-asthmatic competitive athletes?

    PubMed

    Kindermann, Wilfried

    2007-01-01

    The prevalence of asthma is higher in elite athletes than in the general population. The risk of developing asthmatic symptoms is the highest in endurance athletes and swimmers. Asthma seems particularly widespread in winter-sport athletes such as cross-country skiers. Asthmatic athletes commonly use inhaled beta(2)-agonists to prevent and treat asthmatic symptoms. However, beta(2)-agonists are prohibited according to the Prohibited List of the World Anti-Doping Agency. An exception can be made only for the substances formoterol, salbutamol, salmeterol and terbutaline by inhalation, as long as a therapeutic use exemption has been applied for and granted. In this context, the question arises of whether beta(2)-agonists have ergogenic benefits justifying the prohibition of these substances. In 17 of 19 randomised placebo-controlled trials in non-asthmatic competitive athletes, performance-enhancing effects of the inhaled beta(2)-agonists formoterol, salbutamol, salmeterol and terbutaline could not be proved. This is particularly true for endurance performance, anaerobic power and strength performance. In three of four studies, even supratherapeutic doses of salbutamol (800-1200 microg) had no ergogenic effect. In contrast to inhaled beta(2)-agonists, oral administration of salbutamol seems to be able to improve the muscle strength and the endurance performance. There appears to be no justification to prohibit inhaled beta(2)-agonists from the point of view of the ergogenic effects. PMID:17241101

  8. Three-dimensional common-feature hypotheses for octopamine agonist 2-(arylimino)imidazolidines.

    PubMed

    Hirashima, Akinori; Morimoto, Masako; Kuwano, Eiichi; Taniguchi, Eiji; Eto, Morifusa

    2002-01-01

    Three-dimensional pharmacophore hypotheses were built from a set of 10 octopamine (OA) agonist 2-(Arylimino)imidazolidines (AIIs), 2-(Arylimino)thiazolidines (AITs) and 2-(Arylimino)oxazolidines (AIOs). Among the 10 common-featured models generated by program Catalyst/HipHop, a hypothesis including a ring aromatic (RA), a positive ionizable (PI) and three hydrophobic aliphatic (HpAl) features was considered to be important in evaluating the OA-agonist activity. Active OA agonist 2,6-Et2 AII mapped well onto all the RA, PI and HpAl features of the hypothesis. On the other hand, less active compounds were shown to be difficult to achieve the energetically favorable conformation which is found in the active molecules in order to fit the 3-D common-feature pharmacophore models. Taken together, 2,6-Et2-Ph and foramidine structures are important as OA agonists. The present studies on OA agonists demonstrate that a RA, a PI and three HpAl sites located on the molecule seem to be essential for OA-agonist activity.

  9. Alpha/sub 1/ receptor coupling events initiated by methoxy-substituted tolazoline partial agonists

    SciTech Connect

    Wick, P.; Keung, A.; Deth, R.

    1986-03-01

    A series of mono- and dimethyoxy substituted tolazoline derivatives, known to be partial agonists at the alpha/sub 1/ receptor, were compared with the ..cap alpha../sub 1/ selective full agonist phenylephrine (PE) on isolated strips of rabbit aorta Agonist activity was evaluated in contraction, /sup 45/Ca influx, /sup 45/Ca efflux, and /sup 32/P-Phospholipid labelling studies. Maximum contractile responses for the 2-, 3-, and 3, 5- methoxy substituted tolazoline derivatives (10/sup -5/M) were 53.8, 67.6 and 99.7% of the PE (10/sup -5/M) response respectively. These same partial agonists caused a stimulation of /sup 45/Ca influx to the extent of 64, 86, and 95% of the PE response respectively. In /sup 45/Ca efflux studies, (a measure of the intracellular Ca/sup +2/ release) the tolazolines caused: 30%, 63%, and 78% of the PE stimulated level. /sup 32/P-Phosphatidic acid (PA) labelling was measured as an index of PI turnover after ..cap alpha../sub 1/ receptor stimulation. Compared to PE, the 2-, 3-, and 3,5- methoxy substituted tolazoline derivatives caused 22, 46, and 72% PA labelling. The above values are all in reasonable accord with the rank order or agonist activity shown in maximum contractile responses. The results of this investigation suggest that partial agonists stimulate ..cap alpha.. receptor coupling events at a level which is quantitatively comparable to their potencies in causing contraction of arterial smooth muscle.

  10. The good, the bad, and the ugly: agonistic behaviour in juvenile crocodilians.

    PubMed

    Brien, Matthew L; Lang, Jeffrey W; Webb, Grahame J; Stevenson, Colin; Christian, Keith A

    2013-01-01

    We examined agonistic behaviour in seven species of hatchling and juvenile crocodilians held in small groups (N = 4) under similar laboratory conditions. Agonistic interactions occurred in all seven species, typically involved two individuals, were short in duration (5-15 seconds), and occurred between 1600-2200 h in open water. The nature and extent of agonistic interactions, the behaviours displayed, and the level of conspecific tolerance varied among species. Discrete postures, non-contact and contact movements are described. Three of these were species-specific: push downs by C. johnstoni; inflated tail sweeping by C. novaeguineae; and, side head striking combined with tail wagging by C. porosus. The two long-snouted species (C. johnstoni and G. gangeticus) avoided contact involving the head and often raised the head up out of the way during agonistic interactions. Several behaviours not associated with aggression are also described, including snout rubbing, raising the head up high while at rest, and the use of vocalizations. The two most aggressive species (C. porosus, C. novaeguineae) appeared to form dominance hierarchies, whereas the less aggressive species did not. Interspecific differences in agonistic behaviour may reflect evolutionary divergence associated with morphology, ecology, general life history and responses to interspecific conflict in areas where multiple species have co-existed. Understanding species-specific traits in agonistic behaviour and social tolerance has implications for the controlled raising of different species of hatchlings for conservation, management or production purposes.

  11. Selective Retinoic Acid Receptor γ Agonists Promote Repair of Injured Skeletal Muscle in Mouse

    PubMed Central

    Di Rocco, Agnese; Uchibe, Kenta; Larmour, Colleen; Berger, Rebecca; Liu, Min; Barton, Elisabeth R.; Iwamoto, Masahiro

    2016-01-01

    Retinoic acid signaling regulates several biological events, including myogenesis. We previously found that retinoic acid receptor γ (RARγ) agonist blocks heterotopic ossification, a pathological bone formation that mostly occurs in the skeletal muscle. Interestingly, RARγ agonist also weakened deterioration of muscle architecture adjacent to the heterotopic ossification lesion, suggesting that RARγ agonist may oppose skeletal muscle damage. To test this hypothesis, we generated a critical defect in the tibialis anterior muscle of 7-week-old mice with a cautery, treated them with RARγ agonist or vehicle corn oil, and examined the effects of RARγ agonist on muscle repair. The muscle defects were partially repaired with newly regenerating muscle cells, but also filled with adipose and fibrous scar tissue in both RARγ-treated and control groups. The fibrous or adipose area was smaller in RARγ agonist–treated mice than in the control. In addition, muscle repair was remarkably delayed in RARγ-null mice in both critical defect and cardiotoxin injury models. Furthermore, we found a rapid increase in retinoid signaling in lacerated muscle, as monitored by retinoid signaling reporter mice. Together, our results indicate that endogenous RARγ signaling is involved in muscle repair and that selective RARγ agonists may be beneficial to promote repair in various types of muscle injuries. PMID:26205250

  12. Identification of Ecdysone Hormone Receptor Agonists as a Therapeutic Approach for Treating Filarial Infections

    PubMed Central

    Mhashilkar, Amruta S.; Vankayala, Sai L.; Liu, Canhui; Kearns, Fiona; Mehrotra, Priyanka; Tzertzinis, George; Palli, Subba R.; Woodcock, H. Lee; Unnasch, Thomas R.

    2016-01-01

    Background A homologue of the ecdysone receptor has previously been identified in human filarial parasites. As the ecdysone receptor is not found in vertebrates, it and the regulatory pathways it controls represent attractive potential chemotherapeutic targets. Methodology/ Principal Findings Administration of 20-hydroxyecdysone to gerbils infected with B. malayi infective larvae disrupted their development to adult stage parasites. A stable mammalian cell line was created incorporating the B. malayi ecdysone receptor ligand-binding domain, its heterodimer partner and a secreted luciferase reporter in HEK293 cells. This was employed to screen a series of ecdysone agonist, identifying seven agonists active at sub-micromolar concentrations. A B. malayi ecdysone receptor ligand-binding domain was developed and used to study the ligand-receptor interactions of these agonists. An excellent correlation between the virtual screening results and the screening assay was observed. Based on both of these approaches, steroidal ecdysone agonists and the diacylhydrazine family of compounds were identified as a fruitful source of potential receptor agonists. In further confirmation of the modeling and screening results, Ponasterone A and Muristerone A, two compounds predicted to be strong ecdysone agonists stimulated expulsion of microfilaria and immature stages from adult parasites. Conclusions The studies validate the potential of the B. malayi ecdysone receptor as a drug target and provide a means to rapidly evaluate compounds for development of a new class of drugs against the human filarial parasites. PMID:27300294

  13. Metabolic mapping of A3 adenosine receptor agonist MRS5980.

    PubMed

    Fang, Zhong-Ze; Tosh, Dilip K; Tanaka, Naoki; Wang, Haina; Krausz, Kristopher W; O'Connor, Robert; Jacobson, Kenneth A; Gonzalez, Frank J

    2015-09-15

    (1S,2R,3S,4R,5S)-4-(2-((5-Chlorothiophen-2-yl)ethynyl)-6-(methylamino)-9H-purin-9-yl)-2,3-dihydroxy-N-methylbicyclo[3.1.0]hexane-1-carboxamide (MRS5980) is an A3AR selective agonist containing multiple receptor affinity- and selectivity-enhancing modifications and a therapeutic candidate drug for many inflammatory diseases. Metabolism-related poor pharmacokinetic behavior and toxicities are a major reason for drug R&D failure. Metabolomics with UPLC-MS was employed to profile the metabolism of MRS5980 and MRS5980-induced disruption of endogenous compounds. Recombinant drug-metabolizing enzymes screening experiment were used to determine the enzymes involved in MRS5980 metabolism. Analysis of lipid metabolism-related genes was performed to investigate the reason for MRS5980-induced lipid metabolic disorders. Unsupervised principal components analysis separated the control and MRS5980 treatment groups in feces, urine, and liver samples, but not in bile and serum. The major ions mainly contributing to the separation of feces and urine were oxidized MRS5980, glutathione (GSH) conjugates and cysteine conjugate (degradation product of the GSH conjugates) of MRS5980. The major ions contributing to the group separation of liver samples were phosphatidylcholines. In vitro incubation experiments showed the involvement of CYP3A enzymes in the oxidative metabolism of MRS5980 and direct GSH reactivity of MRS5980. The electrophilic attack by MRS5980 is a minor pathway and did not alter GSH levels in liver or liver histology, and thus may be of minor clinical consequence. Gene expression analysis further showed decreased expression of PC biosynthetic genes choline kinase a and b, which further accelerated conversion of lysophosphatidylcholine to phosphatidylcholines through increasing the expression of lysophosphatidylcholine acyltransferase 3. These data will be useful to guide rational design of drugs targeting A3AR, considering efficacy, metabolic elimination, and

  14. Cardiovascular Effects of Glucagon-Like Peptide-1 Receptor Agonists

    PubMed Central

    Kang, Yu Mi

    2016-01-01

    Glucagon-like peptide-1 (GLP-1) is a member of the proglucagon incretin family, and GLP-1 receptor agonists (RAs) have been introduced as a new class of antidiabetic medications in the past decade. The benefits of GLP-1 RAs are derived from their pleiotropic effects, which include glucose-dependent insulin secretion, suppressed glucagon secretion, and reduced appetite. Moreover, GLP-1 RAs also exert beneficial roles on multiple organ systems in which the GLP-1 receptors exist, including the cardiovascular system. Cardiovascular effects of GLP-1 RAs have been of great interest since the burden from cardiovascular diseases (CVD) has been unbearably increasing in a diabetic population worldwide, despite strict glycemic control and advanced therapeutic techniques to treat CVD. Preclinical studies have already demonstrated the beneficial effects of GLP-1 on myocardium and vascular endothelium, and many clinical studies evaluating changes in surrogate markers of CVD have suggested potential benefits from the use of GLP-1 RAs. Data from numerous clinical trials primarily evaluating the antihyperglycemic effects of multiple GLP-1 RAs have also revealed that changes in most CVD risk markers reported as secondary outcomes have been in favor of GLP-1 RAs treatment. However, to date, there is only one randomized clinical trial of GLP-1 RAs (the ELIXA study) evaluating major cardiovascular events as their primary outcomes, and in this study, a neutral cardiovascular effect of lixisenatide was observed in high-risk diabetic subjects. Therefore, the results of ongoing CVD outcome trials with the use of GLP-1 RAs should be awaited to elucidate the translation of benefits previously seen in CVD risk marker studies into large clinical trials with primary cardiovascular outcomes. PMID:27118277

  15. Metabolic mapping of A3 adenosine receptor agonist MRS5980

    PubMed Central

    Fang, Zhong-Ze; Tosh, Dilip K.; Tanaka, Naoki; Wang, Haina; Krausz, Kristopher W.; O'Connor, Robert; Jacobson, Kenneth A.; Gonzalez, Frank J.

    2015-01-01

    (1S,2R,3S,4R,5S)-4-(2-((5-Chlorothiophen-2-yl)ethynyl)-6-(methylamino)-9H-purin-9-yl)-2,3-dihydroxy-N-methylbicyclo[3.1.0]hexane-1-carboxamide (MRS5980) is an A3AR selective agonist containing multiple receptor affinity- and selectivity-enhancing modifications and a therapeutic candidate drug for many inflammatory diseases. Metabolism-related poor pharmacokinetic behavior and toxicities are a major reason of drug R&D failure. Metabolomics with UPLC-MS was employed to profile the metabolism of MRS5980 and MRS5980-induced disruption of endogenous compounds. Recombinant drug-metabolizing enzymes screening experiment were used to determine the enzymes involved in MRS5980 metabolism. Analysis of lipid metabolism-related genes was performed to investigate the reason for MRS5980-induced lipid metabolic disorders. Unsupervised principal components analysis separated the control and MRS5980 treatment group in feces, urine, and liver samples, but not in bile and serum. The major ions mainly contributing to the separation for feces and urine were oxidized MRS5980, glutathione (GSH) conjugates and cysteine conjugate (degradation product of the GSH conjugates) of MRS5980. The major ions contributing to the group separation of liver samples were phosphatidylcholines. In vitro incubation experiments showed the major involvement of CYP3A enzymes in the oxidative metabolism of MRS5980 and direct GSH reactivity of MRS5980. The electrophilic attack by MRS5980 is a minor pathway and did not alter GSH levels in liver or liver histology, and thus may be of minor clinical consequence. Gene expression analysis further showed decreased expression of PC biosynthetic genes choline kinase a and b, which further accelerated conversion of lysophosphatidylcholine to phosphatidylcholines through increasing the expression of lysophosphatidylcholine acyltransferase 3. These data will be useful to guide rational design of drugs targeting A3AR, considering efficacy, metabolic elimination, and

  16. Radiolabelled D2 agonists as prolactinoma imaging agents

    SciTech Connect

    Otto, C.A.

    1989-08-01

    During the past year, further studies on mAChR were conducted. These studies included verification of the difference in pituitary distribution based on ligand charge. The pituitary localization of TRB. A neutral mAChR ligand, was verified. The lack of QNB blockade of TRB uptake was tested by blockage with scopolamine, another mAChR antagonist and by testing the effect in a different strain of rat. Neither scopolamine or change of rat strain had any effect. We concluded that TRB uptake in pituitary is not a receptor-mediated process. Further studies were conducted with an additional quaternized mAChR ligand: MQNB. Pituitary localization of MQNB, like MTRB, could be blocked by pretreatment with QNB. We have tentatively concluded that permanent charge on a mAChR antagonist changes the mechanism of uptake in the pituitary. Time course studies and the effects of DES on myocardial uptake are reported. A brief report on preliminary results of evaluation of quaternized mAChR ligands in the heart is included. In a limited series of such ligands, we have observed a single binding site and a difference in B{sub max} values: QNB competition studies yield larger B{sub max} values than studies with {sup 3}H-NMS. Progress in the synthesis of D{sub 2} agonists includes solving a synthetic problem and preparation of the cold'' analogue of N-0437 using procedures applicable to eventual synthesis with {sup 11}C-CH{sub 3}I. 2 refs., 5 figs., 1 tab.

  17. GABAA agonist reduces visual awareness: a masking-EEG experiment.

    PubMed

    van Loon, Anouk M; Scholte, H Steven; van Gaal, Simon; van der Hoort, Björn J J; Lamme, Victor A F

    2012-04-01

    Consciousness can be manipulated in many ways. Here, we seek to understand whether two such ways, visual masking and pharmacological intervention, share a common pathway in manipulating visual consciousness. We recorded EEG from human participants who performed a backward-masking task in which they had to detect a masked figure form its background (masking strength was varied across trials). In a within-subject design, participants received dextromethorphan (a N-methyl-d-aspartate receptor antagonist), lorazepam (LZP; a GABA(A) receptor agonist), scopolamine (a muscarine receptor antagonist), or placebo. The behavioral results show that detection rate decreased with increasing masking strength and that of all the drugs, only LZP induced a further decrease in detection rate. Figure-related ERP signals showed three neural events of interest: (1) an early posterior occipital and temporal generator (94-121 msec) that was not influenced by any pharmacological manipulation nor by masking, (2) a later bilateral perioccipital generator (156-211 msec) that was reduced by masking as well as LZP (but not by any other drugs), and (3) a late bilateral occipital temporal generator (293-387 msec) that was mainly affected by masking. Crucially, only the intermediate neural event correlated with detection performance. In combination with previous findings, these results suggest that LZP and masking both reduce visual awareness by means of modulating late activity in the visual cortex but leave early activation intact. These findings provide the first evidence for a common mechanism for these two distinct ways of manipulating consciousness. PMID:22264199

  18. RXR partial agonist produced by side chain repositioning of alkoxy RXR full agonist retains antitype 2 diabetes activity without the adverse effects.

    PubMed

    Kawata, Kohei; Morishita, Ken-ichi; Nakayama, Mariko; Yamada, Shoya; Kobayashi, Toshiki; Furusawa, Yuki; Arimoto-Kobayashi, Sakae; Oohashi, Toshitaka; Makishima, Makoto; Naitou, Hirotaka; Ishitsubo, Erika; Tokiwa, Hiroaki; Tai, Akihiro; Kakuta, Hiroki

    2015-01-22

    We previously reported RXR partial agonist CBt-PMN (1-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydro-2-naphthyl)-1H-benzotriazole-5-carboxylic acid: 5, EC50 = 143 nM, Emax = 75%), which showed a potent glucose-lowering effect without causing serious adverse effects. However, it remains important to elucidate the structural requirements for RXR efficacy and the glucose-lowering effect because RXR-permissive heterodimers such as PPAR/RXR or LXR/RXR are reported to be activated differently depending upon the chemical structure of RXR agonists. In this work, we show that an RXR partial agonist, NEt-4IB (6-[ethyl-(4-isobutoxy-3-isopropylphenyl)amino]pyridine-3-carboxylic acid: 8b, EC50 = 169 nM, Emax = 55%), can be obtained simply by repositioning the side chains (interchanging the isobutoxy and isopropoxy groups) at the hydrophobic moiety of the RXR full agonist NEt-3IB (6-[ethyl-(3-isobutoxy-4-isopropylphenyl)amino]pyridine-3-carboxylic acid: 7b, EC50 = 19 nM). NEt-4IB (8b) showed antitype 2 diabetes activity without the above side effects upon repeated oral administration to mice at 10 mg/kg/day, similarly to 5. PMID:25486327

  19. Agonist-bound structure of the human P2Y12 receptor

    PubMed Central

    Zhang, Jin; Zhang, Kaihua; Gao, Zhan-Guo; Paoletta, Silvia; Zhang, Dandan; Han, Gye Won; Li, Tingting; Ma, Limin; Zhang, Wenru; Müller, Christa E.; Yang, Huaiyu; Jiang, Hualiang; Cherezov, Vadim; Katritch, Vsevolod; Jacobson, Kenneth A.; Stevens, Raymond C.; Wu, Beili; Zhao, Qiang

    2014-01-01

    The P2Y12 receptor (P2Y12R), one of eight members of the P2YR family expressed in humans, has been identified as one of the most prominent clinical drug targets for inhibition of platelet aggregation. Consequently, extensive mutagenesis and modeling studies of the P2Y12R have revealed many aspects of agonist/antagonist binding1-4. However, the details of agonist and antagonist recognition and function at the P2Y12R remain poorly understood at the molecular level. Here, we report the structures of the human P2Y12R in complex with a full agonist 2-methylthio-adenosine-5′-diphosphate (2MeSADP, a close analogue of endogenous agonist ADP) at 2.5 Å resolution, and the corresponding ATP derivative 2-methylthio-adenosine-5′-triphosphate (2MeSATP) at 3.1 Å resolution. Analysis of these structures, together with the structure of the P2Y12R with antagonist ethyl 6-(4-((benzylsulfonyl)carbamoyl)piperidin-1-yl)-5-cyano-2-methylnicotinate (AZD1283)5, reveals dramatic conformational changes between nucleotide and non-nucleotide ligand complexes in the extracellular regions, providing the first insight into a different ligand binding landscape in the δ-group of class A G protein-coupled receptors (GPCRs). Agonist and non-nucleotide antagonist adopt different orientations in the P2Y12R, with only partially overlapped binding pockets. The agonist-bound P2Y12R structure answers long-standing ambiguities surrounding P2Y12R-agonist recognition, and reveals interactions with several residues that had not been reported to be involved in agonist binding. As a first example of a GPCR where agonist access to the binding pocket requires large scale rearrangements in the highly malleable extracellular region, the structural studies therefore will provide invaluable insight into the pharmacology and mechanisms of action of agonists and different classes of antagonists for the P2Y12R and potentially for other closely related P2YRs. PMID:24784220

  20. Dopamine agonists, anti-progestins, anti-androgens, long-term-release GnRH agonists and anti-estrogens in canine reproduction: a review.

    PubMed

    Gobello, C

    2006-10-01

    Over the last 10 years, new drugs have been applied to canine reproduction, widening the spectrum of therapeutic possibilities for diseases that were previously surgically treated, and facilitating better control of the estrous cycle and fertility. Some are not approved for use in dogs; their use is experimental and further clinical trials are necessary. Dopamine agonists such as cabergoline, bromocriptine or metergoline are ergoderivative alkaloids that exert an anti-prolactinergic effect via stimulation of D2 pituitary receptors or inhibition of central serotoninergic ones. Their main indication is suppression of lactation. Anti-prolactinergic compounds have also been successfully used for pregnancy termination and shortening of interestrous intervals. Anti-progestins, (e.g. mifepristone and aglepristone) are synthetic steroids that bind with high affinity to progesterone (P4) receptors, preventing P4 from exerting its biological effects. Anti-progestins have been indicated in P4-dependent conditions, such as pregnancy termination, induction of parturition and the medical treatment of pyometra. Several groups of drugs have been described to have anti-androgenic properties through different mechanisms of action: progestins, receptor binding anti-androgens (e.g. flutamide), competitive enzyme inhibitors (e.g. finasteride), aromatase inhibitors, and GnRH agonists. Their main application is medical treatment of benign prostatic hyperplasia. Long-term release formulations of GnRH agonists (e.g. leuprolide or deslorelin acetate) postponed puberty and reversibly suppressed reproductive function in male and female dogs for periods exceeding 1 year. Anti-estrogens (e.g. clomiphene and tamoxifen citrate) are synthetic non-steroidal type I anti-estrogenic compounds that competitively block estrogen receptors with a combined antagonist-agonistic effect. In dogs, their action is more agonistic than antagonistic. PMID:16542717

  1. Selective α4β2 nicotinic acetylcholine receptor agonists target epigenetic mechanisms in cortical GABAergic neurons.

    PubMed

    Maloku, Ekrem; Kadriu, Bashkim; Zhubi, Adrian; Dong, Erbo; Pibiri, Fabio; Satta, Rosalba; Guidotti, Alessandro

    2011-06-01

    Nicotine improves cognitive performance and attention in both experimental animals and in human subjects, including patients affected by neuropsychiatric disorders. However, the specific molecular mechanisms underlying nicotine-induced behavioral changes remain unclear. We have recently shown in mice that repeated injections of nicotine, which achieve plasma concentrations comparable to those reported in high cigarette smokers, result in an epigenetically induced increase of glutamic acid decarboxylase 67 (GAD(67)) expression. Here we explored the impact of synthetic α(4)β(2) and α(7) nAChR agonists on GABAergic epigenetic parameters. Varenicline (VAR), a high-affinity partial agonist at α(4)β(2) and a lower affinity full agonist at α(7) neuronal nAChR, injected in doses of 1-5 mg/kg/s.c. twice daily for 5 days, elicited a 30-40% decrease of cortical DNA methyltransferase (DNMT)1 mRNA and an increased expression of GAD(67) mRNA and protein. This upregulation of GAD(67) was abolished by the nAChR antagonist mecamylamine. Furthermore, the level of MeCP(2) binding to GAD(67) promoters was significantly reduced following VAR administration. This effect was abolished when VAR was administered with mecamylamine. Similar effects on cortical DNMT1 and GAD(67) expression were obtained after administration of A-85380, an agonist that binds to α(4)β(2) but has negligible affinity for α(3)β(4) or α(7) subtypes containing nAChR. In contrast, PNU-282987, an agonist of the homomeric α(7) nAChR, failed to decrease cortical DNMT1 mRNA or to induce GAD(67) expression. The present study suggests that the α(4)β(2) nAChR agonists may be better suited to control the epigenetic alterations of GABAergic neurons in schizophrenia than the α(7) nAChR agonists.

  2. Find novel dual-agonist drugs for treating type 2 diabetes by means of cheminformatics

    PubMed Central

    Liu, Lei; Ma, Ying; Wang, Run-Ling; Xu, Wei-Ren; Wang, Shu-Qing; Chou, Kuo-Chen

    2013-01-01

    The high prevalence of type 2 diabetes mellitus in the world as well as the increasing reports about the adverse side effects of the existing diabetes treatment drugs have made developing new and effective drugs against the disease a very high priority. In this study, we report ten novel compounds found by targeting peroxisome proliferator-activated receptors (PPARs) using virtual screening and core hopping approaches. PPARs have drawn increasing attention for developing novel drugs to treat diabetes due to their unique functions in regulating glucose, lipid, and cholesterol metabolism. The reported compounds are featured with dual functions, and hence belong to the category of dual agonists. Compared with the single PPAR agonists, the dual PPAR agonists, formed by combining the lipid benefit of PPARα agonists (such as fibrates) and the glycemic advantages of the PPARγ agonists (such as thiazolidinediones), are much more powerful in treating diabetes because they can enhance metabolic effects while minimizing the side effects. This was observed in the studies on molecular dynamics simulations, as well as on absorption, distribution, metabolism, and excretion, that these novel dual agonists not only possessed the same function as ragaglitazar (an investigational drug developed by Novo Nordisk for treating type 2 diabetes) did in activating PPARα and PPARγ, but they also had more favorable conformation for binding to the two receptors. Moreover, the residues involved in forming the binding pockets of PPARα and PPARγ among the top ten compounds are explicitly presented, and this will be very useful for the in-depth conduction of mutagenesis experiments. It is anticipated that the ten compounds may become potential drug candidates, or at the very least, the findings reported here may stimulate new strategies or provide useful insights for designing new and more powerful dual-agonist drugs for treating type 2 diabetes. PMID:23630413

  3. PPAR agonists regulate brain gene expression: relationship to their effects on ethanol consumption.

    PubMed

    Ferguson, Laura B; Most, Dana; Blednov, Yuri A; Harris, R Adron

    2014-11-01

    Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that act as ligand-activated transcription factors. Although prescribed for dyslipidemia and type-II diabetes, PPAR agonists also possess anti-addictive characteristics. PPAR agonists decrease ethanol consumption and reduce withdrawal severity and susceptibility to stress-induced relapse in rodents. However, the cellular and molecular mechanisms facilitating these properties have yet to be investigated. We tested three PPAR agonists in a continuous access two-bottle choice (2BC) drinking paradigm and found that tesaglitazar (PPARα/γ; 1.5 mg/kg) and fenofibrate (PPARα; 150 mg/kg) decreased ethanol consumption in male C57BL/6J mice while bezafibrate (PPARα/γ/β; 75 mg/kg) did not. We hypothesized that changes in brain gene expression following fenofibrate and tesaglitazar treatment lead to reduced ethanol drinking. We studied unbiased genomic profiles in areas of the brain known to be important for ethanol dependence, the prefrontal cortex (PFC) and amygdala, and also profiled gene expression in liver. Genomic profiles from the non-effective bezafibrate treatment were used to filter out genes not associated with ethanol consumption. Because PPAR agonists are anti-inflammatory, they would be expected to target microglia and astrocytes. Surprisingly, PPAR agonists produced a strong neuronal signature in mouse brain, and fenofibrate and tesaglitazar (but not bezafibrate) targeted a subset of GABAergic interneurons in the amygdala. Weighted gene co-expression network analysis (WGCNA) revealed co-expression of treatment-significant genes. Functional annotation of these gene networks suggested that PPAR agonists might act via neuropeptide and dopaminergic signaling pathways in the amygdala. Our results reveal gene targets through which PPAR agonists can affect alcohol consumption behavior.

  4. Agonist self-inhibition at the nicotinic acetylcholine receptor a nonspecific action

    SciTech Connect

    Forman, S.A.; Firestone, L.L.; Miller, K.W.

    1987-05-19

    Agonist concentration-response relationships at nicotinic postsynaptic receptors were established by measuring /sup 86/Rb/sup +/ efflux from acetylcholine receptor rich native Torpedo membrane vesicles under three different conditions: (1) integrated net ion efflux (in 10 s) from untreated vesicles, (2) integrated net efflux from vesicles in which most acetylcholine sites were irreversibly blocked with ..cap alpha..-bungarotoxin, and (3) initial rates of efflux (5-100 ms) from vesicles that were partially blocked with ..cap alpha..-bungarotoxin. Exposure to acetylcholine, carbamylcholine, suberyldicholine, phenyltrimethylammonium, or (-)-nicotine over 10/sup 8/-fold concentration ranges results in bell-shaped ion flux response curves due to stimulation of acetylcholine receptor channel opening at low concentrations and inhibition of channel function at 60-2000 times higher concentrations. Concentrations of agonists that inhibit their own maximum /sup 86/Rb/sup +/ efflux by 50% (K/sub B/ values) are 110, 211, 3.0, 39, and 8.9 mM, respectively, for the agonists listed above. For acetylcholine and carbamylcholine, K/sub B/ values determined from both 10-s and 15-ms efflux measurements are the same, indicating that the rate of agonist-induced desensitization increases to maximum at concentrations lower than those causing self-inhibition. For all partial and full agonists studied, Hill coefficients for self-inhibition are close to 1.0. Concentrations of agonists up to 8 times K/sub B/ did not change the order parameter reported by a spin-labeled fatty acid incorporated in Torpedo membranes. The authors conclude that agonist self-inhibition cannot be attributed to a general nonspecific membrane perturbation. Instead, these results are consistent with a saturable site of action either at the lipid-protein interface or on the acetylcholine receptor protein itself.

  5. β2-Adrenoceptor agonists as novel, safe and potentially effective therapies for Amyotrophic lateral sclerosis (ALS).

    PubMed

    Bartus, Raymond T; Bétourné, Alexandre; Basile, Anthony; Peterson, Bethany L; Glass, Jonathan; Boulis, Nicholas M

    2016-01-01

    Amyotrophic lateral sclerosis (ALS) is a chronic and progressive neuromuscular disease for which no cure exists and better treatment options are desperately needed. We hypothesize that currently approved β2-adrenoceptor agonists may effectively treat the symptoms and possibly slow the progression of ALS. Although β2-agonists are primarily used to treat asthma, pharmacologic data from animal models of neuromuscular diseases suggest that these agents may have pharmacologic effects of benefit in treating ALS. These include inhibiting protein degradation, stimulating protein synthesis, inducing neurotrophic factor synthesis and release, positively modulating microglial and systemic immune function, maintaining the structural and functional integrity of motor endplates, and improving energy metabolism. Moreover, stimulation of β2-adrenoceptors can activate a range of downstream signaling events in many different cell types that could account for the diverse array of effects of these agents. The evidence supporting the possible therapeutic benefits of β2-agonists is briefly reviewed, followed by a more detailed review of clinical trials testing the efficacy of β-agonists in a variety of human neuromuscular maladies. The weight of evidence of the potential benefits from treating these diseases supports the hypothesis that β2-agonists may be efficacious in ALS. Finally, ways to monitor and manage the side effects that may arise with chronic administration of β2-agonists are evaluated. In sum, effective, safe and orally-active β2-agonists may provide a novel and convenient means to reduce the symptoms of ALS and possibly delay disease progression, affording a unique opportunity to repurpose these approved drugs for treating ALS, and rapidly transforming the management of this serious, unmet medical need. PMID:26459114

  6. PPAR agonists regulate brain gene expression: relationship to their effects on ethanol consumption.

    PubMed

    Ferguson, Laura B; Most, Dana; Blednov, Yuri A; Harris, R Adron

    2014-11-01

    Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that act as ligand-activated transcription factors. Although prescribed for dyslipidemia and type-II diabetes, PPAR agonists also possess anti-addictive characteristics. PPAR agonists decrease ethanol consumption and reduce withdrawal severity and susceptibility to stress-induced relapse in rodents. However, the cellular and molecular mechanisms facilitating these properties have yet to be investigated. We tested three PPAR agonists in a continuous access two-bottle choice (2BC) drinking paradigm and found that tesaglitazar (PPARα/γ; 1.5 mg/kg) and fenofibrate (PPARα; 150 mg/kg) decreased ethanol consumption in male C57BL/6J mice while bezafibrate (PPARα/γ/β; 75 mg/kg) did not. We hypothesized that changes in brain gene expression following fenofibrate and tesaglitazar treatment lead to reduced ethanol drinking. We studied unbiased genomic profiles in areas of the brain known to be important for ethanol dependence, the prefrontal cortex (PFC) and amygdala, and also profiled gene expression in liver. Genomic profiles from the non-effective bezafibrate treatment were used to filter out genes not associated with ethanol consumption. Because PPAR agonists are anti-inflammatory, they would be expected to target microglia and astrocytes. Surprisingly, PPAR agonists produced a strong neuronal signature in mouse brain, and fenofibrate and tesaglitazar (but not bezafibrate) targeted a subset of GABAergic interneurons in the amygdala. Weighted gene co-expression network analysis (WGCNA) revealed co-expression of treatment-significant genes. Functional annotation of these gene networks suggested that PPAR agonists might act via neuropeptide and dopaminergic signaling pathways in the amygdala. Our results reveal gene targets through which PPAR agonists can affect alcohol consumption behavior. PMID:25036611

  7. Differential effects of subtype-specific nicotinic acetylcholine receptor agonists on early and late hippocampal LTP.

    PubMed

    Kroker, Katja S; Rast, Georg; Rosenbrock, Holger

    2011-12-01

    Brain nicotinic acetylcholine receptors are involved in several neuropsychiatric disorders, e.g. Alzheimer's and Parkinson's diseases, Tourette's syndrome, schizophrenia, depression, autism, attention deficit hyperactivity disorder, and anxiety. Currently, approaches selectively targeting the activation of specific nicotinic acetylcholine receptors are in clinical development for treatment of memory impairment of Alzheimer's disease patients. These are α4β2 and α7 nicotinic acetylcholine receptor agonists which are believed to enhance cholinergic and glutamatergic neurotransmission, respectively. In order to gain a better insight into the mechanistic role of these two nicotinic acetylcholine receptors in learning and memory, we investigated the effects of the α4β2 nicotinic acetylcholine receptor agonist TC-1827 and the α7 nicotinic acetylcholine receptor partial agonist SSR180711 on hippocampal long-term potentiation (LTP), a widely accepted cellular experimental model of memory formation. Generally, LTP is distinguished in an early and a late form, the former being protein-synthesis independent and the latter being protein-synthesis dependent. TC-1827 was found to increase early LTP in a bell-shaped dose dependent manner, but did not affect late LTP. In contrast, the α7 nicotinic acetylcholine receptor partial agonist SSR180711 showed enhancing effects on both early and late LTP in a bell-shaped manner. Furthermore, SSR180711 not only increased early LTP, but also transformed it into late LTP, which was not observed with the α4β2 nicotinic acetylcholine receptor agonist. Therefore, based on these findings α7 nicotinic acetylcholine receptor (partial) agonists appear to exhibit stronger efficacy on memory improvement than α4β2 nicotinic acetylcholine receptor agonists. PMID:21968142

  8. β2-Adrenergic agonists attenuate organic dust-induced lung inflammation.

    PubMed

    Romberger, Debra J; Heires, Art J; Nordgren, Tara M; Poole, Jill A; Toews, Myron L; West, William W; Wyatt, Todd A

    2016-07-01

    Agricultural dust exposure results in significant lung inflammation, and individuals working in concentrated animal feeding operations (CAFOs) are at risk for chronic airway inflammatory diseases. Exposure of bronchial epithelial cells to aqueous extracts of hog CAFO dusts (HDE) leads to inflammatory cytokine production that is driven by protein kinase C (PKC) activation. cAMP-dependent protein kinase (PKA)-activating agents can inhibit PKC activation in epithelial cells, leading to reduced inflammatory cytokine production following HDE exposure. β2-Adrenergic receptor agonists (β2-agonists) activate PKA, and we hypothesized that β2-agonists would beneficially impact HDE-induced adverse airway inflammatory consequences. Bronchial epithelial cells were cultured with the short-acting β2-agonist salbutamol or the long-acting β2-agonist salmeterol prior to stimulation with HDE. β2-Agonist treatment significantly increased PKA activation and significantly decreased HDE-stimulated IL-6 and IL-8 production in a concentration- and time-dependent manner. Salbutamol treatment significantly reduced HDE-induced intracellular adhesion molecule-1 expression and neutrophil adhesion to epithelial cells. Using an established intranasal inhalation exposure model, we found that salbutamol pretreatment reduced airway neutrophil influx and IL-6, TNF-α, CXCL1, and CXCL2 release in bronchoalveolar lavage fluid following a one-time exposure to HDE. Likewise, when mice were pretreated daily with salbutamol prior to HDE exposure for 3 wk, HDE-induced neutrophil influx and inflammatory mediator production were also reduced. The severity of HDE-induced lung pathology in mice repetitively exposed to HDE for 3 wk was also decreased with daily salbutamol pretreatment. Together, these results support the need for future clinical investigations to evaluate the utility of β2-agonist therapies in the treatment of airway inflammation associated with CAFO dust exposure. PMID:27190062

  9. CAR and PXR agonists stimulate hepatic bile acid and bilirubin detoxification and elimination pathways in mice.

    PubMed

    Wagner, Martin; Halilbasic, Emina; Marschall, Hanns-Ulrich; Zollner, Gernot; Fickert, Peter; Langner, Cord; Zatloukal, Kurt; Denk, Helmut; Trauner, Michael

    2005-08-01

    Induction of hepatic phase I/II detoxification enzymes and alternative excretory pumps may limit hepatocellular accumulation of toxic biliary compounds in cholestasis. Because the nuclear xenobiotic receptors constitutive androstane receptor (CAR) and pregnane X receptor (PXR) regulate involved enzymes and transporters, we aimed to induce adaptive alternative pathways with different CAR and PXR agonists in vivo. Mice were treated with the CAR agonists phenobarbital and 1,4-bis-[2-(3,5-dichlorpyridyloxy)]benzene, as well as the PXR agonists atorvastatin and pregnenolone-16alpha-carbonitrile. Hepatic bile acid and bilirubin-metabolizing/detoxifying enzymes (Cyp2b10, Cyp3a11, Ugt1a1, Sult2a1), their regulatory nuclear receptors (CAR, PXR, farnesoid X receptor), and bile acid/organic anion and lipid transporters (Ntcp, Oatp1,2,4, Bsep, Mrp2-4, Mdr2, Abcg5/8, Asbt) in the liver and kidney were analyzed via reverse-transcriptase polymerase chain reaction and Western blotting. Potential functional relevance was tested in common bile duct ligation (CBDL). CAR agonists induced Mrp2-4 and Oatp2; PXR agonists induced only Mrp3 and Oatp2. Both PXR and CAR agonists profoundly stimulated bile acid-hydroxylating/detoxifying enzymes Cyp3a11 and Cyp2b10. In addition, CAR agonists upregulated bile acid-sulfating Sult2a1 and bilirubin-glucuronidating Ugt1a1. These changes were accompanied by reduced serum levels of bilirubin and bile acids in healthy and CBDL mice and by increased levels of polyhydroxylated bile acids in serum and urine of cholestatic mice. Atorvastatin significantly increased Oatp2, Mdr2, and Asbt, while other transporters and enzymes were moderately affected. In conclusion, administration of specific CAR or PXR ligands results in coordinated stimulation of major hepatic bile acid/bilirubin metabolizing and detoxifying enzymes and hepatic key alternative efflux systems, effects that are predicted to counteract cholestasis. PMID:15986414

  10. Preclinical pharmacology of mGlu2/3 receptor agonists: novel agents for schizophrenia?

    PubMed

    DD, Darryle D Schoepp; Marek, Gerard J

    2002-04-01

    Agonists for mGlu2/3 receptors decrease the evoked release of glutamate at certain (ie. forebrain / limbic) glutamatergic synapses, indicating that the functional role of mGlu2 and/or mGlu3 receptors is to suppress glutamate excitations. This offers a mechanism for dampening glutamate excitation under pathological states resulting from excessive glutamate release. Based, in part, on the psychotomimetic actions of phencyclidine (PCP)- like drugs, excessive or pathological glutamate release has been implicated in a number of clinical conditions including psychosis. With this in mind, the pharmacology of multiple mGlu2/3 receptor agonists have been investigated in PCP treated rats. Agonists for mGlu2/3 receptors such as LY354740 and LY379268 have been shown to block certain behavioral responses to PCP in rats. The effects of mGlu2/3 agonists on PCP-induced behaviors are blocked by a low doses of a selective mGlu2/3 receptor antagonist, indicating that these actions are mediated via mGlu2/3 receptors. In addition, mGlu2/3 agonists potently suppress glutamate release in rat prefrontal cortex, as reflected by excitatory post-synaptic potentials (EPSPs) induced by serotonin (5-HT) acting on 5HT(2A) receptors. These actions of LY354740 and LY379268 are also blocked by a selective mGlu2/3 antagonist. Atypical antipsychotic drugs such as clozapine also suppress 5-HT-induced EPSPs in this brain region, thus suggesting a common pathway for the actions of atypical antipsychotic drugs and mGlu2/3 receptor agonists. As glutamatergic dysfunction has been implicated in psychotic states and possibly in the etiology of schizophrenia, clinical studies with mGlu2/3 agonists may be warranted to further explore the validity of the glutamatergic hypothesis of schizophrenia. PMID:12769628

  11. Antimitogenic effect of bitter taste receptor agonists on airway smooth muscle cells.

    PubMed

    Sharma, Pawan; Panebra, Alfredo; Pera, Tonio; Tiegs, Brian C; Hershfeld, Alena; Kenyon, Lawrence C; Deshpande, Deepak A

    2016-02-15

    Airway remodeling is a hallmark feature of asthma and chronic obstructive pulmonary disease. Clinical studies and animal models have demonstrated increased airway smooth muscle (ASM) mass, and ASM thickness is correlated with severity of the disease. Current medications control inflammation and reverse airway obstruction effectively but have limited effect on remodeling. Recently we identified the expression of bitter taste receptors (TAS2R) on ASM cells, and activation with known TAS2R agonists resulted in ASM relaxation and bronchodilation. These studies suggest that TAS2R can be used as new therapeutic targets in the treatment of obstructive lung diseases. To further establish their effectiveness, in this study we aimed to determine the effects of TAS2R agonists on ASM growth and promitogenic signaling. Pretreatment of healthy and asthmatic human ASM cells with TAS2R agonists resulted in a dose-dependent inhibition of ASM proliferation. The antimitogenic effect of TAS2R ligands was not dependent on activation of protein kinase A, protein kinase C, or high/intermediate-conductance calcium-activated K(+) channels. Immunoblot analyses revealed that TAS2R agonists inhibit growth factor-activated protein kinase B phosphorylation without affecting the availability of phosphatidylinositol 3,4,5-trisphosphate, suggesting TAS2R agonists block signaling downstream of phosphatidylinositol 3-kinase. Furthermore, the antimitogenic effect of TAS2R agonists involved inhibition of induced transcription factors (activator protein-1, signal transducer and activator of transcription-3, E2 factor, nuclear factor of activated T cells) and inhibition of expression of multiple cell cycle regulatory genes, suggesting a direct inhibition of cell cycle progression. Collectively, these findings establish the antimitogenic effect of TAS2R agonists and identify a novel class of receptors and signaling pathways that can be targeted to reduce or prevent airway remodeling as well as

  12. Glucagon-like peptide-1 receptor agonist administration suppresses both water and saline intake in rats.

    PubMed

    McKay, N J; Daniels, D

    2013-10-01

    Glucagon-like peptide-1 (GLP-1) plays an important role in energy homeostasis. Injections of GLP-1 receptor (GLP-1R) agonists suppress food intake, and endogenous GLP-1 is released when nutrients enter the gut. There is also growing evidence that the GLP-1 system is involved in the regulation of body fluid homeostasis. GLP-1R agonists suppress water intake independent of their effects on food intake. It is unknown, however, whether this suppressive effect of GLP-1R agonists extends to saline intake. Accordingly, we tested the effect of the GLP-1R agonists liraglutide (0.05 μg) and exendin-4 (0.05 μg) on water and saline intake, as stimulated either by angiotensin II (AngII) or by water deprivation with partial rehydration (WD-PR). Each agonist suppressed AngII-induced water intake; however, only exendin-4 suppressed saline intake. WD-PR-induced water and saline intakes were both attenuated by each agonist. Analysis of drinking microstructure after WD-PR found a reliable effect of the agonists on burst number. Furthermore, exendin-4 conditioned a robust taste avoidance to saccharine; however, there was no similar effect of liraglutide. To evaluate the relevance of the conditioned taste avoidance, we tested whether inducing visceral malaise by injection of lithium chloride (LiCl) suppressed fluid intake. Injection of LiCl did not suppress water or saline intakes. Overall, these results indicate that the fluid intake suppression by GLP-1R activation is not selective to water intake, is a function of post-ingestive feedback, and is not secondary to visceral malaise.

  13. Glucagon-like peptide-1 receptor agonists suppress water intake independent of effects on food intake.

    PubMed

    McKay, Naomi J; Kanoski, Scott E; Hayes, Matthew R; Daniels, Derek

    2011-12-01

    Glucagon-like peptide-1 (GLP-1) is produced by and released from the small intestine following ingestion of nutrients. GLP-1 receptor (GLP-1R) agonists applied peripherally or centrally decrease food intake and increase glucose-stimulated insulin secretion. These effects make the GLP-1 system an attractive target for the treatment of type 2 diabetes mellitus and obesity. In addition to these more frequently studied effects of GLP-1R stimulation, previous reports indicate that GLP-1R agonists suppress water intake. The present experiments were designed to provide greater temporal resolution and site specificity for the effect of GLP-1 and the long-acting GLP-1R agonists, exendin-4 and liraglutide, on unstimulated water intake when food was and was not available. All three GLP-1R ligands suppressed water intake after peripheral intraperitoneal administration, both in the presence of and the absence of food; however, the magnitude and time frame of water intake suppression varied by drug. GLP-1 had an immediate, but transient, hypodipsic effect when administered peripherally, whereas the water intake suppression by IP exendin-4 and liraglutide was much more persistent. Additionally, intracerebroventricular administration of GLP-1R agonists suppressed water intake when food was absent, but the suppression of intake showed modest differences depending on whether the drug was administered to the lateral or fourth ventricle. To the best of our knowledge, this is the first demonstration of GLP-1 receptor agonists affecting unstimulated, overnight intake in the absence of food, the first test for antidipsogenic effects of hindbrain application of GLP-1 receptor agonists, and the first test of a central effect (forebrain or hindbrain) of liraglutide on water intake. Overall, these results show that GLP-1R agonists have a hypodipsic effect that is independent of GLP-1R-mediated effects on food intake, and this occurs, in part, through central nervous system GLP-1R activation.

  14. PPAR agonists regulate brain gene expression: Relationship to their effects on ethanol consumption

    PubMed Central

    Ferguson, Laura B.; Most, Dana; Blednov, Yuri A.; Harris, R. Adron

    2014-01-01

    Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that act as ligand-activated transcription factors. Although prescribed for dyslipidemia and type-II diabetes, PPAR agonists also possess anti-addictive characteristics. PPAR agonists decrease ethanol consumption and reduce withdrawal severity and susceptibility to stress-induced relapse in rodents. However, the cellular and molecular mechanisms facilitating these properties have yet to be investigated. We tested three PPAR agonists in a continuous access two-bottle choice (2BC) drinking paradigm and found that tesaglitazar (PPARα/γ; 1.5 mg/kg) and fenofibrate (PPARα; 150 mg/kg) decreased ethanol consumption in male C57BL/6J mice while bezafibrate (PPARα/γ/β; 75 mg/kg) did not. We hypothesized that changes in brain gene expression following fenofibrate and tesaglitazar treatment lead to reduced ethanol drinking. We studied unbiased genomic profiles in areas of the brain known to be important for ethanol dependence, the prefrontal cortex (PFC) and amygdala, and also profiled gene expression in liver. Genomic profiles from the non-effective bezafibrate treatment were used to filter out genes not associated with ethanol consumption. Because PPAR agonists are anti-inflammatory, they would be expected to target microglia and astrocytes. Surprisingly, PPAR agonists produced a strong neuronal signature in mouse brain, and fenofibrate and tesaglitazar (but not bezafibrate) targeted a subset of GABAergic interneurons in the amygdala. Weighted gene co-expression network analysis (WGCNA) revealed co-expression of treatment-significant genes. Functional annotation of these gene networks suggested that PPAR agonists might act via neuropeptide and dopaminergic signaling pathways in the amygdala. Our results reveal gene targets through which PPAR agonists can affect alcohol consumption behavior. PMID:25036611

  15. Signaling pathways used by EGF to stimulate conjunctival goblet cell secretion.

    PubMed

    Hodges, Robin R; Bair, Jeffrey A; Carozza, Richard B; Li, Dayu; Shatos, Marie A; Dartt, Darlene A

    2012-10-01

    The purpose of this study was to identify the signaling pathways that epidermal growth factor (EGF) uses to stimulate mucin secretion from cultured rat conjunctival goblet cells and to compare the pathways used by EGF with those used by the known secretagogue muscarinic, cholinergic agonists. To this end, goblet cells from rat conjunctiva were grown in culture using RPMI media. For immunofluorescence experiments, antibodies against EGF receptor (EGFR) and ERK 2 as well as muscarinic receptors (M(1)AchR, M(2)AchR, and M(3)AchR) were used, and the cells viewed by fluorescence microscopy. Intracellular [Ca(2+)] ([Ca(2+)](i)) was measured using fura 2/AM. Glycoconjugate secretion was determined after cultured goblet cells were preincubated with inhibitors, and then stimulated with EGF or the cholinergic agonist carbachol (Cch). Goblet cell secretion was measured using an enzyme-linked lectin assay with UEA-I or ELISA for MUC5AC. In cultured goblet cells EGF stimulated an increase in [Ca(2+)](i) in a concentration-dependent manner. EGF-stimulated increase in [Ca(2+)](i) was blocked by inhibitors of the EGF receptor and removal of extracellular Ca(2+). Inhibitors against the EGFR and ERK 1/2 blocked EGF-stimulated mucin secretion. In addition, cultured goblet cells expressed M(1)AchR, M(2)AchR, and M(3)AchRs. Cch-stimulated increase in [Ca(2+)](i) was blocked by inhibitors for the M(1)AchRs, matrix metalloproteinases, and EGF receptors. Inhibitors against the EGF receptor and ERK 1/2 also blocked Cch-stimulated mucin secretion. We conclude that in conjunctival goblet cells, EGF itself increases [Ca(2+)](i) and activates ERK 1/2 to stimulate mucin secretion. EGF-stimulated secretion is dependent on extracellular Ca(2+). This mechanism of action is similar to cholinergic agonists that use muscarinic receptors to transactivate the EGF receptor, increase [Ca(2+)](i), and activate ERK 1/2 leading to an increase in mucin secretion.

  16. Successful Treatment of Chronic Hepatitis C with Triple Therapy in an Opioid Agonist Treatment Program

    PubMed Central

    Litwin, Alain H.; Soloway, Irene J.; Cockerham-Colas, Lauren; Reynoso, Sheila; Heo, Moonseong; Tenore, Christopher; Roose, Robert J.

    2015-01-01

    Background People who inject drugs (PWID) constitute 10 million people globally with hepatitis C virus, including many opioid agonist treatment patients. Little data exist describing clinical outcomes for patients receiving HCV treatment with direct-acting antiviral agents (DAAs) in opioid agonist treatment settings. Methods In this retrospective observational study, we describe clinical outcomes for 50 genotype-1 patients receiving HCV treatment with triple therapy: telaprevir (n = 42) or boceprevir (n = 8) in combination with pegylated interferon and ribavirin on-site in an opioid agonist treatment program. Results Overall, 70% achieved an end of treatment response (ETR) and 62% achieved a sustained virological response (SVR). These treatment outcomes are nearly equivalent to previously published HCV outcomes shown in registration trials, despite high percentages of recent drug use prior to treatment (52%), ongoing drug use during treatment (45%) and psychiatric comorbidity (86%). Only 12% (n=6) discontinued antiviral treatment early for non-virological reasons. Four patients received a blood transfusion, and one discontinued telaprevir due to severe rash. Conclusions These data demonstrate that on-site HCV treatment with direct-acting antiviral agents is effective in opioid agonist treatment patients including patients who are actively using drugs. Future interferon-free regimens will likely be even more effective. Opioid agonist treatment programs represent an opportunity to safely and effectively treat chronic hepatitis C, and PWID should have unrestricted access to DAAs. PMID:26341685

  17. Effects of an LH-RH agonist on reproductive responses and endocrinological parameters in landais ganders.

    PubMed

    Sellier, N; Do Thi, D X; Rousselot-Pailley, D; Péczely, P; de Reviers, M; Guémené, D

    1995-10-15

    Semen quantitative (sperm production) and qualitative parameters (percentage of live and normal spermatozoa, sperm motility, egg fertility and hatchability), as well as hormonal parameters (LH and testosterone plasma concentrations) were compared for landais ganders, which were treated or not, with an LH-RH agonist prior to being sexually active. Treatment with the LH-RH agonist at this physiological stage delayed the onset of sperm production in some of the treated males. Although, comparable data were obtained during the first half of the reproductive period, treatment with the LH-RH agonist maintained sperm output at higher levels during its second half. Although the percentage of normal and live spermatozoa, sperm motility and true hatchability did not differ, the LH-RH agonist treatment had a positive effect on gosling production because of the higher fertility of the treated birds during the second part of the reproductive period. Treatment induced a large short-term decrease in testosterone levels followed by a rebound, leading to higher levels during the second half of the reproductive period. We conclude that treatment of ganders with an LH-RH agonist partially prevented the naturally occurring decline in sperm production and induced an increase in the rate of fertility rates during the second half of the productive period.

  18. GLP-1 Receptor Agonists: Nonglycemic Clinical Effects in Weight Loss and Beyond

    PubMed Central

    Ryan, Donna; Acosta, Andres

    2015-01-01

    Obective Glucagon-like peptide-1 (GLP-1) receptor agonists are indicated for treatment of type 2 diabetes since they mimic the actions of native GLP-1 on pancreatic islet cells, stimulating insulin release, while inhibiting glucagon release, in a glucose-dependent manner. The observation of weight loss has led to exploration of their potential as antiobesity agents, with liraglutide 3.0 mg day−1 approved for weight management in the US on December 23, 2014, and in the EU on March 23, 2015. This review examines the potential nonglycemic effects of GLP-1 receptor agonists. Methods A literature search was conducted to identify preclinical and clinical evidence on nonglycemic effects of GLP-1 receptor agonists. Results GLP-1 receptors are distributed widely in a number of tissues in humans, and their effects are not limited to the well-recognized effects on glycemia. Nonglycemic effects include weight loss, which is perhaps the most widely recognized nonglycemic effect. In addition, effects on the cardiovascular, neurologic, and renal systems and on taste perception may occur independently of weight loss. Conclusions GLP-1 receptor agonists may provide other nonglycemic clinical effects besides weight loss. Understanding these effects is important for prescribers in using GLP-1 receptor agonists for diabetic patients, but also if approved for chronic weight management. PMID:25959380

  19. Identification of dual PPARα/γ agonists and their effects on lipid metabolism.

    PubMed

    Gao, Quanqing; Hanh, Jacky; Váradi, Linda; Cairns, Rose; Sjöström, Helena; Liao, Vivian W Y; Wood, Peta; Balaban, Seher; Ong, Jennifer Ai; Lin, Hsuan-Yu Jennifer; Lai, Felcia; Hoy, Andrew J; Grewal, Thomas; Groundwater, Paul W; Hibbs, David E

    2015-12-15

    The three peroxisome proliferator-activated receptor (PPAR) isoforms; PPARα, PPARγ and PPARδ, play central roles in lipid metabolism and glucose homeostasis. Dual PPARα/γ agonists, which stimulate both PPARα and PPARγ isoforms to similar extents, are gaining popularity as it is believed that they are able to ameliorate the unwanted side effects of selective PPARα and PPARγ agonists; and may also be used to treat dyslipidemia and type 2 diabetes mellitus simultaneously. In this study, virtual screening of natural product libraries, using both structure-based and ligand-based drug discovery approaches, identified ten potential dual PPARα/γ agonist lead compounds (9-13 and 16-20). In vitro assays confirmed these compounds to show no statistically significant toxicity to cells, with the exception of compound 12 which inhibited cell growth to 74.5%±3.5 and 54.1%±3.7 at 50μM and 100μM, respectively. In support of their potential as dual PPARα/γ agonists, all ten compounds upregulated the expression of cholesterol transporters ABCA1 and ABCG1 in THP-1 macrophages, with indoline derivative 16 producing the greatest elevation (2.3-fold; 3.3-fold, respectively). Furthermore, comparable to the activity of established PPARα and PPARγ agonists, compound 16 stimulated triacylglycerol accumulation during 3T3-L1 adipocyte differentiation as well as fatty acid β-oxidation in HuH7 hepatocytes. PMID:26616289

  20. Evolution of the Bifunctional Lead μ Agonist / δ Antagonist Containing the Dmt-Tic Opioid Pharmacophore.

    PubMed

    Balboni, Gianfranco; Salvadori, Severo; Trapella, Claudio; Knapp, Brian I; Bidlack, Jean M; Lazarus, Lawrence H; Peng, Xuemei; Neumeyer, John L

    2010-02-17

    Based on a renewed importance recently attributed to bi- or multifunctional opioids, we report the synthesis and pharmacological evaluation of some analogues derived from our lead μ agonist / δ antagonist, H-Dmt-Tic-Gly-NH-Bzl. Our previous studies focused on the importance of the C-teminal benzyl function in the induction of such bifunctional activity. The introduction of some substituents in the para position of the phenyl ring (-Cl, -CH(3), partially -NO(2), inactive -NH(2)) was found to give a more potent μ agonist / antagonist effect associated with a relatively unmodified δ antagonist activity (pA(2) = 8.28-9.02). Increasing the steric hindrance of the benzyl group (using diphenylmethyl and tetrahydroisoquinoline functionalities) substantially maintained the μ agonist and δ antagonist activities of the lead compound. Finally and quite unexpectedly D-Tic2, considered as a wrong opioid message now; inserted into the reference compound in lieu of L-Tic, provided a μ agonist / δ agonist better than our reference ligand (H-Dmt-Tic-Gly-NH-Ph) and was endowed with the same pharmacological profile.

  1. Use of clinically available PPAR agonists for heart failure; do the risks outweigh the potential benefits?

    PubMed

    Sarma, Satyam

    2012-06-01

    PPAR agonists represent a heterogeneous group of compounds that have been used in the treatment of cardiovascular and metabolic diseases for over thirty years. While the primary indications for PPAR agonist therapy focus on hyperlipidemia and diabetes, there is a growing body of pre-clinical data that suggests they may be beneficial in the treatment of heart failure; a disease marked by abnormal myocardial metabolism, fibrosis and insulin insensitivity. PPAR agonist treatment in numerous animal models of systolic heart failure have demonstrated improvement in cardiac function with decreased fibrosis, improved contractility and endothelial function. However, considerable controversy exists on the cardiac safety profile of PPAR agonists, particularly concern for inducing lipotoxicty and precipitating or worsening heart failure. In addition during pre-clinical testing, many compounds have been associated with increased death and adverse cardiovascular outcomes casting a pall over their future use for treating disorders of myocardial function. This article will review cardiac pathways involved in PPAR activation and their potential regulation of maladaptive pathways involved in heart failure and highlight molecular mechanisms that may contribute to adverse events and raise safety concerns. Specific attention will be focused on PPAR alpha and gamma, subtypes for which commercially available PPAR agonists are currently available.

  2. PPAR-γ Agonists and Their Effects on IGF-I Receptor Signaling: Implications for Cancer

    PubMed Central

    Belfiore, A.; Genua, M.; Malaguarnera, R.

    2009-01-01

    It is now well established that the development and progression of a variety of human malignancies are associated with dysregulated activity of the insulin-like growth factor (IGF) system. In this regard, promising drugs have been developed to target the IGF-I receptor or its ligands. These therapies are limited by the development of insulin resistance and compensatory hyperinsulinemia, which in turn, may stimulate cancer growth. Novel therapeutic approaches are, therefore, required. Synthetic PPAR-γ agonists, such as thiazolidinediones (TZDs), are drugs universally used as antidiabetic agents in patients with type 2 diabetes. In addition of acting as insulin sensitizers, PPAR-γ agonists mediate in vitro and in vivo pleiotropic anticancer effects. At least some of these effects appear to be linked with the downregulation of the IGF system, which is induced by the cross-talk of PPAR-γ agonists with multiple components of the IGF system signaling. As hyperinsulinemia is an emerging cancer risk factor, the insulin lowering action of PPAR-γ agonists may be expected to be also beneficial to reduce cancer development and/or progression. In light of these evidences, TZDs or other PPAR-γ agonists may be exploited in those tumors “addicted” to the IGF signaling and/or in tumors occurring in hyperinsulinemic patients. PMID:19609453

  3. Combined sodium ion sensitivity in agonist binding and internalization of vasopressin V1b receptors

    PubMed Central

    Koshimizu, Taka-aki; Kashiwazaki, Aki; Taniguchi, Junichi

    2016-01-01

    Reducing Na+ in the extracellular environment may lead to two beneficial effects for increasing agonist binding to cell surface G-protein coupled receptors (GPCRs): reduction of Na+-mediated binding block and reduce of receptor internalization. However, such combined effects have not been explored. We used Chinese Hamster Ovary cells expressing vasopressin V1b receptors as a model to explore Na+ sensitivity in agonist binding and receptor internalization. Under basal conditions, a large fraction of V1b receptors is located intracellularly, and a small fraction is in the plasma membrane. Decreases in external Na+ increased cell surface [3H]AVP binding and decreased receptor internalization. Substitution of Na+ by Cs+ or NH4+ inhibited agonist binding. To suppress receptor internalization, the concentration of NaCl, but not of CsCl, had to be less than 50 mM, due to the high sensitivity of the internalization machinery to Na+ over Cs+. Iso-osmotic supplementation of glucose or NH4Cl maintained internalization of the V1b receptor, even in a low-NaCl environment. Moreover, iodide ions, which acted as a counter anion, inhibited V1b agonist binding. In summary, we found external ionic conditions that could increase the presence of high-affinity state receptors at the cell surface with minimum internalization during agonist stimulations. PMID:27138239

  4. The therapeutic potential of nicotinic acetylcholine receptor agonists for pain control.

    PubMed

    Decker, M W; Meyer, M D; Sullivan, J P

    2001-10-01

    Due to the limitations of currently available analgesics, a number of novel alternatives are currently under investigation, including neuronal nicotinic acetylcholine receptor (nAChR) agonists. During the 1990s, the discovery of the antinociceptive properties of the potent nAChR agonist epibatidine in rodents sparked interest in the analgesic potential of this class of compounds. Although epibatidine also has several mechanism-related toxicities, the identification of considerable nAChR diversity suggested that the toxicities and therapeutic actions of the compound might be mediated by distinct receptor subtypes. Consistent with this view, a number of novel nAChR agonists with antinociceptive activity and improved safety profiles in preclinical models have now been identified, including A-85380, ABT-594, DBO-83, SIB-1663 and RJR-2403. Of these, ABT-594 is the most advanced and is currently in Phase II clinical evaluation. Nicotinically-mediated antinociception has been demonstrated in a variety of rodent pain models and is likely mediated by the activation of descending inhibitory pathways originating in the brainstem with the predominant high-affinity nicotine site in brain, the alpha4beta2 subtype, playing a critical role. Thus, preclinical findings suggest that nAChR agonists have the potential to be highly efficacious treatments in a variety of pain states. However, clinical proof-of-principle studies will be required to determine if nAChR agonists are active in pathological pain.

  5. Modulation Effect of Peroxisome Proliferator-Activated Receptor Agonists on Lipid Droplet Proteins in Liver.

    PubMed

    Zhu, Yun-Xia; Zhang, Ming-Liang; Zhong, Yuan; Wang, Chen; Jia, Wei-Ping

    2016-01-01

    Peroxisome proliferator-activated receptor (PPAR) agonists are used for treating hyperglycemia and type 2 diabetes. However, the mechanism of action of these agonists is still under investigation. The lipid droplet-associated proteins FSP27/CIDEC and LSDP5, regulated directly by PPARγ and PPARα, are associated with hepatic steatosis and insulin sensitivity. Here, we evaluated the expression levels of FSP27/CIDEC and LSDP5 and the regulation of these proteins by consumption of a high-fat diet (HFD) or administration of PPAR agonists. Mice with diet-induced obesity were treated with the PPARγ or PPARα agonist, pioglitazone or fenofibrate, respectively. Liver tissues from db/db diabetic mice and human were also collected. Interestingly, FSP27/CIEDC was expressed in mouse and human livers and was upregulated in obese C57BL/6J mice. Fenofibrate treatment decreased hepatic triglyceride (TG) content and FSP27/CIDEC protein expression in mice fed an HFD diet. In mice, LSDP5 was not detected, even in the context of insulin resistance or treatment with PPAR agonists. However, LSDP5 was highly expressed in humans, with elevated expression observed in the fatty liver. We concluded that fenofibrate greatly decreased hepatic TG content and FSP27/CIDEC protein expression in mice fed an HFD, suggesting a potential regulatory role for fenofibrate in the amelioration of hepatic steatosis.

  6. Neuroprotection by a selective estrogen receptor beta agonist in a mouse model of global ischemia.

    PubMed

    Carswell, H V O; Macrae, I M; Gallagher, L; Harrop, E; Horsburgh, K J

    2004-10-01

    The present study employs selective estrogen receptor (ER) agonists to determine whether 17beta-estradiol-induced neuroprotection in global ischemia is receptor mediated and, if so, which subtype of receptor (ERalpha or ERbeta) is predominantly responsible. Halothane-anesthetized female C57Bl/6J mice were ovariectomized, and osmotic minipumps containing ERbeta agonist diarylpropiolnitrile (DPN) (8 mg.kg(-1).day(-1), n = 12) or vehicle (50% DMSO in 0.9% saline) (n = 9) or ERalpha agonist propyl pyrazole triol (PPT) (2 mg.kg(-1).day(-1), n = 13) or vehicle (50% DMSO in 0.9% saline) (n = 10) were implanted subcutaneously. One week later transient global ischemia was induced by bilateral carotid artery occlusion under halothane anesthesia, and the mice were perfusion fixed 72 h later. ERbeta agonist DPN significantly reduced ischemic damage by 70% in the caudate nucleus and 55% in the CA1 region compared with vehicle controls (P < 0.05, Mann-Whitney U-statistic). In contrast, pretreatment with the ERalpha agonist PPT had no effect on the extent of neuronal damage compared with controls. The data indicate a significant estrogen receptor-mediated neuroprotection in a global cerebral ischemia model involving ERbeta.

  7. Computational Prediction and Biochemical Analyses of New Inverse Agonists for the CB1 Receptor.

    PubMed

    Scott, Caitlin E; Ahn, Kwang H; Graf, Steven T; Goddard, William A; Kendall, Debra A; Abrol, Ravinder

    2016-01-25

    Human cannabinoid type 1 (CB1) G-protein coupled receptor is a potential therapeutic target for obesity. The previously predicted and experimentally validated ensemble of ligand-free conformations of CB1 [Scott, C. E. et al. Protein Sci. 2013 , 22 , 101 - 113 ; Ahn, K. H. et al. Proteins 2013 , 81 , 1304 - 1317] are used here to predict the binding sites for known CB1-selective inverse agonists including rimonabant and its seven known derivatives. This binding pocket, which differs significantly from previously published models, is used to identify 16 novel compounds expected to be CB1 inverse agonists by exploiting potential new interactions. We show experimentally that two of these compounds exhibit inverse agonist properties including inhibition of basal and agonist-induced G-protein coupling activity, as well as an enhanced level of CB1 cell surface localization. This demonstrates the utility of using the predicted binding sites for an ensemble of CB1 receptor structures for designing new CB1 inverse agonists.

  8. Alcohol Screening among Opioid Agonist Patients in a Primary Care Clinic and an Opioid Treatment Program

    PubMed Central

    Klimas, Jan; Muench, John; Wiest, Katharina; Croff, Raina; Rieckmann, Traci; McCarty, Dennis

    2016-01-01

    Problem alcohol use is associated with adverse health and economic outcomes, especially among people in opioid agonist treatment. Screening, brief intervention and referral to treatment (SBIRT) are effective in reducing alcohol use; however, issues involved in SBIRT implementation among opioid agonist patients are unknown. To assess identification and treatment of alcohol use disorders, we reviewed clinical records of opioid agonist patients screened for an alcohol use disorder in a primary care clinic (n =208) and in an opioid treatment program (n = 204) over a two year period. In the primary care clinic, 193 (93%) buprenorphine patients completed an annual alcohol screening and six (3%) had elevated AUDIT scores. Among the patients treated in the opioid treatment program, an alcohol abuse or dependence diagnosis was recorded for 54 (27%) methadone patients. Practitioner focus groups were completed in the primary care (n = 4 physicians) and the opioid treatment program (n = 11 counsellors) to assess experience with and attitudes towards screening opioid agonist patients for alcohol use disorders. Focus groups suggested organizational, structural, provider, patient and community variables hindered or fostered alcohol screening. Alcohol screening is feasible among opioid agonist patients. Effective implementation, however, requires physician training and systematic changes in workflow. PMID:25715074

  9. Identification of adiponectin receptor agonist utilizing a fluorescence polarization based high throughput assay.

    PubMed

    Sun, Yiyi; Zang, Zhihe; Zhong, Ling; Wu, Min; Su, Qing; Gao, Xiurong; Zan, Wang; Lin, Dong; Zhao, Yan; Zhang, Zhonglin

    2013-01-01

    Adiponectin, the adipose-derived hormone, plays an important role in the suppression of metabolic disorders that can result in type 2 diabetes, obesity, and atherosclerosis. It has been shown that up-regulation of adiponectin or adiponectin receptor has a number of therapeutic benefits. Given that it is hard to convert the full size adiponectin protein into a viable drug, adiponectin receptor agonists could be designed or identified using high-throughput screening. Here, we report on the development of a two-step screening process to identify adiponectin agonists. First step, we developed a high throughput screening assay based on fluorescence polarization to identify adiponectin ligands. The fluorescence polarization assay reported here could be adapted to screening against larger small molecular compound libraries. A natural product library containing 10,000 compounds was screened and 9 hits were selected for validation. These compounds have been taken for the second-step in vitro tests to confirm their agonistic activity. The most active adiponectin receptor 1 agonists are matairesinol, arctiin, (-)-arctigenin and gramine. The most active adiponectin receptor 2 agonists are parthenolide, taxifoliol, deoxyschizandrin, and syringin. These compounds may be useful drug candidates for hypoadiponectin related diseases. PMID:23691032

  10. Reconstitution of high-affinity opioid agonist binding in brain membranes

    SciTech Connect

    Remmers, A.E.; Medzihradsky, F. )

    1991-03-15

    In synaptosomal membranes from rat brain cortex, the {mu} selective agonist ({sup 3}H)dihydromorphine in the absence of sodium, and the nonselective antagonist ({sup 3}H)naltrexone in the presence of sodium, bound to two populations of opioid receptor sites with K{sub d} values of 0.69 and 8.7 nM for dihydromorphine, and 0.34 and 5.5 nM for naltrexone. The addition of 5 {mu}M guanosine 5{prime}-({gamma}-thio)triphosphate (GTP({gamma}S)) strongly reduced high-affinity agonist but not antagonist binding. Exposure of the membranes to high pH reduced the number of GTP({gamma}-{sup 35}S) binding sites by 90% and low K{sub m}, opioid-sensitive GTPase activity by 95%. In these membranes, high-affinity agonist binding was abolished and modulation of residual binding by GTP({gamma}S) was diminished. Alkali treatment of the glioma cell membranes prior to fusion inhibited most of the low K{sub m} GTPase activity and prevented the reconstitution of agonist binding. The results show that high-affinity opioid agonist binding reflects the ligand-occupied receptor - guanine nucleotide binding protein complex.

  11. Pharmacological Profiles of Alpha 2 Adrenergic Receptor Agonists Identified Using Genetically Altered Mice and Isobolographic Analysis

    PubMed Central

    Fairbanks, Carolyn A.; Stone, Laura S.; Wilcox, George L.

    2009-01-01

    Endogenous, descending noradrenergic fibers convey powerful analgesic control over spinal afferent circuitry mediating the rostrad transmission of pain signals. These fibers target alpha 2 adrenergic receptors (α2ARs) on both primary afferent terminals and secondary neurons, and their activation mediates substantial inhibitory control over this transmission, rivaling that of opioid receptors which share similar a similar pattern of distribution. The terminals of primary afferent nociceptive neurons and secondary spinal dorsal horn neurons express α2AAR and α2CAR subtypes, respectively. Spinal delivery of these agents serves to reduce their side effects, which are mediated largely at supraspinal sites, by concentrating the drugs at the spinal level. Targeting these spinal α2ARs with one of five selective therapeutic agonists, clonidine, dexmedetomidine, brimonidine, ST91 and moxonidine, produces significant antinociception that can work in concert with opioid agonists to yield synergistic antinociception. Application of several genetically altered mouse lines had facilitated identification of the primary receptor subtypes that likely mediate the antinociceptive effects of these agents. This review provides first an anatomical description of the localization of the three subtypes in the central nervous system, second a detailed account of the pharmacological history of each of these six primary agonists, and finally a comprehensive report of the specific interactions of other GPCR agonists with each of the six principal α2AR agonists featured. PMID:19393691

  12. Agonists-induced platelet activation varies considerably in healthy male individuals: studies by flow cytometry.

    PubMed

    Panzer, Simon; Höcker, Lisa; Koren, Daniela

    2006-02-01

    Flow cytometric evaluation of platelet function extends our understanding of platelets' role in various clinical conditions associated with either bleeding disorders, thrombosis, or monitoring of antiplatelet therapy. The use of suboptimal concentrations of various agonists may allow assessing the "activatability" of platelets. We determined platelet responsiveness to thrombin-receptor-activating peptide-6, arachidonic acid, adenosine 5c-diphosphate (ADP), epinephrine, collagen, and ristocetin at suboptimal concentrations by determination of P-selectin expression and binding of PAC-1 in 26 healthy male individuals. The response varied considerably from one individual to the next. However, within individuals, responses to all agonists except collagen correlated strongly (p<0.05), suggesting a global variability of platelet responses. Moreover, P-selectin expression and PAC-1 binding were strongly correlated (p<0.05). Interestingly, with epinephrine, PAC-1 positive events outnumbered P-selectin positive events, while this was not seen with the other agonists. Thus, epinephrine may specifically affect the conformational switch mechanism and receptor clustering. Our data indicate that the in vitro response to suboptimal concentrations of agonists varies, but individuals with selective platelet defects may still be identified based on data obtained with the various agonists. PMID:16283308

  13. Functional selectivity of dopamine D1 receptor agonists in regulating the fate of internalized receptors *

    PubMed Central

    Ryman-Rasmussen, Jessica P.; Griffith, Adam; Oloff, Scott; Vaidehi, Nagarajan; Brown, Justin T.; Goddard, William A.; Mailman, Richard B.

    2007-01-01

    Recently, we demonstrated that D1 agonists can cause functionally selective effects when the endpoints of receptor internalization and adenylate cyclase activation are compared. The present study was designed to probe the phenomenon of functional selectivity at the D1 receptor further by testing the hypothesis that structurally dissimilar agonists with efficacies at these endpoints that equal or exceed those of dopamine would differ in ability to influence receptor fate after internalization, a functional endpoint largely unexplored for the D1 receptor. We selected two novel agonists of therapeutic interest that meet these criteria (the isochroman A-77636, and the isoquinoline dinapsoline), and compared the fates of the D1 receptor after internalization in response to these two compounds with that of dopamine. We found that dopamine caused the receptor to be rapidly recycled to the cell surface within 1 h of removal. Conversely, A-77636 caused the receptor to be retained intracellularly up to 48 h after agonist removal. Most surprisingly, the D1 receptor recovered to the cell surface 48 h after removal of dinapsoline. Taken together, these data indicate that these agonists target the D1 receptor to different intracellular trafficking pathways, demonstrating that the phenomenon of functional selectivity at the D1 receptor is operative for cellular events that are temporally downstream of immediate receptor activation. We hypothesize that these differential effects result from interactions of the synthetic ligands with aspects of the D1 receptor that are distal from the ligand binding domain. PMID:17067639

  14. Agonist mediated conformational changes of solubilized calf forebrain muscarinic acetylcholine receptors.

    PubMed

    Vanderheyden, P; Andre, C; de Backer, J P; Vauquelin, G

    1984-10-01

    Muscarinic receptors in calf forebrain membranes can be identified by the specific binding of the radiolabelled antagonist [3H]dexetimide. These receptors (2.8 pM/mg protein) comprise two non-interconvertible subpopulations with respectively high and low agonist affinity but with the same antagonist affinity. For all the agonists tested the low affinity sites represent 85 +/- 5% of the total receptor population. 0.5% Digitonin solubilized extracts contain 0.8 pM muscarinic receptor/mg protein. In contrast with the membranes, these extracts contain only sites with low agonist affinity. The alkylating reagent N-ethylmaleimide causes an increase of the acetylcholine affinity for the low affinity sites in membranes as well as for the solubilized sites. This effect is time dependent until a maximal 3-fold increase in affinity is attained. The rate of N-ethylmaleimide action is enhanced by the concomitant presence of agonists. In contrast, N-ethylmaleimide does not affect antagonist binding. This suggests that agonists mediate a conformational change of both the membrane bound low affinity muscarinic sites and of the solubilized sites, resulting in their increased susceptibility towards NEM alkylation. PMID:6487351

  15. Effect of different beta-adrenergic agonists on the intestinal absorption of galactose and phenylalanine.

    PubMed

    Díez-Sampedro, A; Pérez, M; Cobo, M T; Martínez, J A; Barber, A

    1998-08-01

    Nutrient transport across the mammalian small intestine is regulated by several factors, including intrinsic and extrinsic neural pathways, paracrine modulators, circulating hormones and luminal agents. Because beta-adrenoceptors seem to regulate gastrointestinal functions such as bicarbonate and acid secretion, intestinal motility and gastrointestinal mucosal blood flow, we have investigated the effects of different beta-adrenergic agonists on nutrient absorption by the rat jejunum in-vitro. When intestinal everted sacs were used the beta2-agonist salbutamol had no effect either on galactose uptake by the tissue or mucosal-to-serosal flux whereas mixed beta1- and beta2-agonists (isoproterenol and orciprenaline) and beta3-agonists (BRL 35135, Trecadrine, ICI 198157 and ZD 7114) inhibited galactose uptake and transfer of D-galactose from the mucosal-to-serosal media across the intestinal wall (although the inhibiting effects of isoproterenol and Trecadrine were not statistically significant). In intestinal everted rings both Trecadrine and BRL 35135 clearly reduced galactose uptake, the effect being a result of inhibition of the phlorizin-sensitive component. Total uptake of phenylalanine by the intestinal rings was also reduced by those beta3-adrenergic agonists. These results suggest that beta1- and beta3-adrenergic receptors could be involved in the regulation of intestinal active transport of sugars and amino acids. PMID:9751456

  16. Can HN[double bond, length as m-dash]NH, FN[double bond, length as m-dash]NH, or HN[double bond, length as m-dash]CHOH bridge the σ-hole and the lone pair at P in binary complexes with H2XP, for X = F, Cl, NC, OH, CN, CCH, CH3, and H?

    PubMed

    Del Bene, Janet E; Alkorta, Ibon; Elguero, José

    2015-11-11

    Ab initio MP2/aug'-cc-pVTZ calculations have been carried out to investigate the properties of complexes formed between H2XP, for X = F, Cl, NC, OH, CN, CCH, CH3, and H, and the possible bridging molecules HN[double bond, length as m-dash]NH, FN[double bond, length as m-dash]NH, and HN[double bond, length as m-dash]CHOH. H2XP:HNNH and H2XP:FNNH complexes are stabilized by PN pnicogen bonds, except for H2(CH3)P:FNNH and H3P:FNNH which are stabilized by N-HP hydrogen bonds. H2XP:HNCHOH complexes are stabilized by PN pnicogen bonds and nonlinear O-HP hydrogen bonds. For a fixed H2XP molecule, binding energies decrease in the order HNCHOH > HNNH > FNNH, except for the binding energies of H2(CH3)P and H3P with HNNH and FNNH. Binding energies of complexes with HNCHOH and HNNH increase as the P-N1 distance decreases, but binding energies of complexes with FNNH show little dependence on this distance. The large binding energies of H2XP:HNCHOH complexes arise from a cooperative effect involving electron-pair acceptance by P to form a pnicogen bond, and electron-pair donation by P to form a hydrogen bond. The dominant charge-transfer interaction in these complexes involves electron-pair donation by N across the pnicogen bond, except for complexes in which X is one of the more electropositive substituents, CCH, CH3, and H. For these, lone-pair donation by P across the hydrogen bond dominates. AIM and NBO data for these complexes are consistent with their bonding characteristics, showing molecular graphs with bond critical points and charge-transfer interactions associated with hydrogen and pnicogen bonds. EOM-CCSD spin-spin coupling constants (1p)J(P-N) across the pnicogen bond for each series of complexes correlate with the P-N distance. In contrast, (2h)J(O-P) values for complexes H2XP:HNCHOH do not correlate with the O-P distance, a consequence of the nonlinearity of these hydrogen bonds.

  17. Identification of PPARgamma Partial Agonists of Natural Origin (I): Development of a Virtual Screening Procedure and In Vitro Validation

    PubMed Central

    Guasch, Laura; Sala, Esther; Castell-Auví, Anna; Cedó, Lidia; Liedl, Klaus R.; Wolber, Gerhard; Muehlbacher, Markus; Mulero, Miquel; Pinent, Montserrat; Ardévol, Anna; Valls, Cristina; Pujadas, Gerard; Garcia-Vallvé, Santiago

    2012-01-01

    Background Although there are successful examples of the discovery of new PPARγ agonists, it has recently been of great interest to identify new PPARγ partial agonists that do not present the adverse side effects caused by PPARγ full agonists. Consequently, the goal of this work was to design, apply and validate a virtual screening workflow to identify novel PPARγ partial agonists among natural products. Methodology/Principal Findings We have developed a virtual screening procedure based on structure-based pharmacophore construction, protein-ligand docking and electrostatic/shape similarity to discover novel scaffolds of PPARγ partial agonists. From an initial set of 89,165 natural products and natural product derivatives, 135 compounds were identified as potential PPARγ partial agonists with good ADME properties. Ten compounds that represent ten new chemical scaffolds for PPARγ partial agonists were selected for in vitro biological testing, but two of them were not assayed due to solubility problems. Five out of the remaining eight compounds were confirmed as PPARγ partial agonists: they bind to PPARγ, do not or only moderately stimulate the transactivation activity of PPARγ, do not induce adipogenesis of preadipocyte cells and stimulate the insulin-induced glucose uptake of adipocytes. Conclusions/Significance We have demonstrated that our virtual screening protocol was successful in identifying novel scaffolds for PPARγ partial agonists. PMID:23226391

  18. 3D-Pharmacophore Identification for κ-Opioid Agonists Using Ligand-Based Drug-Design Techniques

    NASA Astrophysics Data System (ADS)

    Yamaotsu, Noriyuki; Hirono, Shuichi

    A selective κ-opioid receptor (KOR) agonist might act as a powerful analgesic without the side effects of μ-opioid receptor-selective drugs such as morphine. The eight classes of known KOR agonists have different chemical structures, making it difficult to construct a pharmacophore model that takes them all into account. Here, we summarize previous efforts to identify the pharmacophore for κ-opioid agonists and propose a new three-dimensional pharmacophore model that encompasses the κ-activities of all classes. This utilizes conformational sampling of agonists by high-temperature molecular dynamics and pharmacophore extraction through a series of molecular superpositions.

  19. Diamine Derivatives as Novel Small-Molecule, Potent, and Subtype-Selective Somatostatin SST3 Receptor Agonists

    PubMed Central

    2014-01-01

    A novel class of small-molecule, highly potent, and subtype-selective somatostatin SST3 agonists was discovered through modification of a SST3 antagonist. As an example, (1R,2S)-9 demonstrated not only potent in vitro SST3 agonist activity but also in vivo SST3 agonist activity in a mouse oral glucose tolerance test (OGTT). These agonists may be useful reagents for studying the physiological roles of the SST3 receptor and may potentially be useful as therapeutic agents. PMID:24944745

  20. Incorporation of Phosphonate into Benzonaphthyridine Toll-like Receptor 7 Agonists for Adsorption to Aluminum Hydroxide.

    PubMed

    Cortez, Alex; Li, Yongkai; Miller, Andrew T; Zhang, Xiaoyue; Yue, Kathy; Maginnis, Jillian; Hampton, Janice; Hall, De Shon; Shapiro, Michael; Nayak, Bishnu; D'Oro, Ugo; Li, Chun; Skibinski, David; Mbow, M Lamine; Singh, Manmohan; O'Hagan, Derek T; Cooke, Michael P; Valiante, Nicholas M; Wu, Tom Y-H

    2016-06-23

    Small molecule Toll-like receptor 7 (TLR7) agonists have been used as vaccine adjuvants by enhancing innate immune activation to afford better adaptive response. Localized TLR7 agonists without systemic exposure can afford good adjuvanticity, suggesting peripheral innate activation (non-antigen-specific) is not required for immune priming. To enhance colocalization of antigen and adjuvant, benzonaphthyridine (BZN) TLR7 agonists are chemically modified with phosphonates to allow adsorption onto aluminum hydroxide (alum), a formulation commonly used in vaccines for antigen stabilization and injection site deposition. The adsorption process is facilitated by enhancing aqueous solubility of BZN analogs to avoid physical mixture of two insoluble particulates. These BZN-phosphonates are highly adsorbed onto alum, which significantly reduced systemic exposure and increased local retention post injection. This report demonstrates a novel approach in vaccine adjuvant design using phosphonate modification to afford adsorption of small molecule immune potentiator (SMIP) onto alum, thereby enhancing co-delivery with antigen. PMID:27270029

  1. Label-Free Cell Phenotypic Identification of D-Luciferin as an Agonist for GPR35.

    PubMed

    Hu, Heidi; Deng, Huayun; Fang, Ye

    2016-01-01

    D-Luciferin (also known as beetle or firefly luciferin) is one of the most widely used bioluminescent reporters for monitoring in vitro or in vivo luciferase activity. The identification of several natural phenols and thieno[3,2-b]thiophene-2-carboxylic acid derivatives as agonists for GPR35, an orphan G protein-coupled receptor, had motivated us to examine the pharmacological activity of D-Luciferin, given that it also contains phenol and carboxylic acid moieties. Here, we describe label-free cell phenotypic assays that ascertain D-Luciferin as a partial agonist for GPR35. The agonistic activity of D-Luciferin at the GPR35 shall evoke careful interpretation of biological data when D-Luciferin or its analogues are used as probes. PMID:27424891

  2. Nicotinamide is an endogenous agonist for a C. elegans TRPV OSM-9 and OCR-4 channel

    PubMed Central

    Upadhyay, Awani; Pisupati, Aditya; Jegla, Timothy; Crook, Matt; Mickolajczyk, Keith J.; Shorey, Matthew; Rohan, Laura E.; Billings, Katherine A.; Rolls, Melissa M.; Hancock, William O.; Hanna-Rose, Wendy

    2016-01-01

    TRPV ion channels are directly activated by sensory stimuli and participate in thermo-, mechano- and chemo-sensation. They are also hypothesized to respond to endogenous agonists that would modulate sensory responses. Here, we show that the nicotinamide (NAM) form of vitamin B3 is an agonist of a Caenorhabditis elegans TRPV channel. Using heterologous expression in Xenopus oocytes, we demonstrate that NAM is a soluble agonist for a channel consisting of the well-studied OSM-9 TRPV subunit and relatively uncharacterized OCR-4 TRPV subunit as well as the orthologous Drosophila Nan-Iav TRPV channel, and we examine stoichiometry of subunit assembly. Finally, we show that behaviours mediated by these C. elegans and Drosophila channels are responsive to NAM, suggesting conservation of activity of this soluble endogenous metabolite on TRPV activity. Our results in combination with the role of NAM in NAD+ metabolism suggest an intriguing link between metabolic regulation and TRPV channel activity. PMID:27731314

  3. PPARγ AGONISTS AS THERAPEUTICS FOR THE TREATMENT OF ALZHEIMER’S DISEASE

    PubMed Central

    Landreth, Gary; Jiang, Qingguang; Mandrekar, Shweta; Heneka, Michael

    2008-01-01

    Alzheimer’s Disease is characterized by the deposition of β-amyloid within the brain parenchyma and is accompanied by the impairment of neuronal metabolism and function, leading to extensive neuronal loss. The disease involves the perturbation of synaptic function, energy and lipid metabolism. The development of amyloid plaques results in the induction of microglial-mediated inflammatory response. The nuclear receptor PPARγ is a ligand-activated transcription factor whose biological actions are to regulate glucose and lipid metabolism and suppress inflammatory gene expression. Thus, agonists of this receptor represent an attractive therapeutic target for AD. There is now an extensive body of evidence that has demonstrated the efficacy of PPARγ agonists in ameliorating disease–related pathology and improved learning and memory in animal models of AD. Recent clinical trials of the PPARγ agonist rosiglitazone have shown significant improvement in memory and cognition in AD patients. Thus, PPARγ represents an important new therapeutic target in treating AD. PMID:18625459

  4. PPAR{alpha} agonists up-regulate organic cation transporters in rat liver cells

    SciTech Connect

    Luci, Sebastian; Geissler, Stefanie; Koenig, Bettina; Koch, Alexander; Stangl, Gabriele I.; Hirche, Frank; Eder, Klaus . E-mail: klaus.eder@landw.uni-halle.de

    2006-11-24

    It has been shown that clofibrate treatment increases the carnitine concentration in the liver of rats. However, the molecular mechanism is still unknown. In this study, we observed for the first time that treatment of rats with the peroxisome proliferator activated receptor (PPAR)-{alpha} agonist clofibrate increases hepatic mRNA concentrations of organic cation transporters (OCTNs)-1 and -2 which act as transporters of carnitine into the cell. In rat hepatoma (Fao) cells, treatment with WY-14,643 also increased the mRNA concentration of OCTN-2. mRNA concentrations of enzymes involved in carnitine biosynthesis were not altered by treatment with the PPAR{alpha} agonists in livers of rats and in Fao cells. We conclude that PPAR{alpha} agonists increase carnitine concentrations in livers of rats and cells by an increased uptake of carnitine into the cell but not by an increased carnitine biosynthesis.

  5. Clinical use of deslorelin (GnRH agonist) in companion animals: a review.

    PubMed

    Lucas, X

    2014-10-01

    Over the years, many contraceptive medications have been developed for companion animals, but many secondary adverse effects have limited their use. A major advancement was achieved with the use of gonadotropin-releasing hormone (GnRH) analogues, mainly GnRH agonists, which mimic the effects of native GnRH. The development of effective low-dose, slow-release implants with potent agonists such as deslorelin (Suprelorin®, Virbac) have allowed their use to become widespread in recent years, with many potential benefits in companion animals. While the major application of deslorelin was initially male contraception, due to its two differing actions, either the stimulation of oestrus or the sterilization of fertility, its use has been increasing in the bitch as well. The aim of this study is to review the applications of deslorelin GnRH agonist implants in companion animal, such as dogs, cats and some exotic pets.

  6. Quantitative Measure of Receptor Agonist and Modulator Equi-Response and Equi-Occupancy Selectivity

    PubMed Central

    Zhang, Rumin; Kavana, Michael

    2016-01-01

    G protein-coupled receptors (GPCRs) are an important class of drug targets. Quantitative analysis by global curve fitting of properly designed dose-dependent GPCR agonism and allosterism data permits the determination of all affinity and efficacy parameters based on a general operational model. We report here a quantitative and panoramic measure of receptor agonist and modulator equi-response and equi-occupancy selectivity calculated from these parameters. The selectivity values help to differentiate not only one agonist or modulator from another, but on-target from off-target receptor or functional pathway as well. Furthermore, in conjunction with target site free drug concentrations and endogenous agonist tones, the allosterism parameters and selectivity values may be used to predict in vivo efficacy and safety margins. PMID:27116909

  7. Structure-guided development of dual β2 adrenergic/dopamine D2 receptor agonists.

    PubMed

    Weichert, Dietmar; Stanek, Markus; Hübner, Harald; Gmeiner, Peter

    2016-06-15

    Aiming to discover dual-acting β2 adrenergic/dopamine D2 receptor ligands, a structure-guided approach for the evolution of GPCR agonists that address multiple targets was elaborated. Starting from GPCR crystal structures, we describe the design, synthesis and biological investigation of a defined set of compounds leading to the identification of the benzoxazinone (R)-3, which shows agonist properties at the adrenergic β2 receptor and substantial G protein-promoted activation at the D2 receptor. This directed approach yielded molecular probes with tuned dual activity. The congener desOH-3 devoid of the benzylic hydroxyl function was shown to be a β2 adrenergic antagonist/D2 receptor agonist with Ki values in the low nanomolar range. The compounds may serve as a promising starting point for the investigation and treatment of neurological disorders. PMID:27132867

  8. Bifunctional epitope-agonist ligands of the bradykinin B(2) receptor.

    PubMed

    Gera, Lajos; Roy, Caroline; Marceau, François

    2013-03-01

    Two bradykinin (BK) B(2) receptor agonists N-terminally extended with the myc epitope were synthesized and evaluated: myc-KPG-BK and myc-KGP-B-9972. The latter was modeled on the inactivation-resistant agonist B-9972 (D-Arg(0), Hyp(3), Igl(5), Oic(7), Igl(8)-BK) and is also resistant to endosomal inactivation. Despite a large loss of affinity relative to the parent peptide, the tagged analogs are conventional agonists in the umbilical vein contractility assay and compete for [(3)H]BK binding at the rabbit B(2) receptor. Endocytosed myc-KGP-B-9972 most effectively carried AlexaFluor-488-conjugated anti-myc monoclonal antibodies into intact cells expressing the B(2) receptor. Results support the prospects of functionally-active cargoes entering cells in a pharmacologically controlled manner.

  9. Metabotropic glutamate receptor agonists potentiate a slow afterdepolarization in CNS neurons

    NASA Technical Reports Server (NTRS)

    Zheng, F.; Gallagher, J. P.

    1992-01-01

    We have previously reported that, in the rat dorsolateral septal nucleus (DLSN), metabotropic glutamate receptor (met-GluR) agonists evoked a slow depolarization accompanied by an increase in membrane conductance and burst firing. We have speculated that the burst firing elicited by met-GluR agonists may be due to activation or enhancement of a non-specific cation current, which exists in some DLSN neurons. Now we report that a slow afterdepolarization (sADP) mediated by a non-specific cation current was potentiated by both 1S,3R-ACPD and quisqualate. In addition, met-GluR agonists unmask a sADP in DLSN neurons which did not show a sADP under control conditions. Our data suggest that a non-specific cation current can be potentiated by activation of the met-GluR.

  10. Thrombin receptor agonist Peptide immobilized in microspheres stimulates reparative processes in rats with gastric ulcer.

    PubMed

    Rusanova, A V; Makarova, A M; Strukova, S M; Markvicheva, E A; Gorbachyova, L R; Stashevskaya, K S; Vasil'eva, T V; Sidorova, E I; Bespalova, Zh D; Grandfils, Ch

    2006-07-01

    The effect of synthetic thrombin receptor (PAR1) agonist peptide encapsulated in microspheres made of lactic and glycolic acid copolymer on tissue reparation was studied in rats with acetate-induced ulcer. PAR1 agonist peptide was immobilized in biodegraded lactic and glycolic acid microspheres by double emulgation, the kinetics of peptide release was analyzed, and the dynamics of ulcer healing was studied in experimental (administration of microspheres with the peptide into the stomach) and two control groups (administration of saline or spheres without peptide). Thrombin receptor agonist peptide gradually released from lactic and glycolic acid microspheres into the stomach shortened the inflammation phase and shifted the proliferation phase to the earlier period, thus accelerating healing of experimental ulcers in rats. PMID:17369897

  11. Competitive Agonists and Antagonists of Steroid Nuclear Receptors: Evolution of the Concept or Its Reversal.

    PubMed

    Smirnova, O V

    2015-10-01

    The mechanisms displaying pure and mixed steroid agonist/antagonist activity as well as principles underlying in vivo action of selective steroid receptor modulators dependent on tissue or cell type including interaction with various types of nuclear receptors are analyzed in this work. Mechanisms of in vitro action for mixed agonist/antagonist steroids are discussed depending on: specific features of their interaction with receptor hormone-binding pocket; steroid-dependent allosteric modulation of interaction between hormone-receptor complex and hormone response DNA elements; features of interacting hormone-receptor complex with protein transcriptional coregulators; level and tissue-specific composition of transcriptional coregulators. A novel understanding regarding context-selective modulators replacing the concept of steroid agonists and antagonists is discussed.

  12. GABAergic Agonists Modulate the Glutamate Release from Frontal Cortex Synaptosomes of Rats with Experimental Autoimmune Encephalomyelitis.

    PubMed

    Fernández Hurst, Nicolás; Chanaday, Natalí L; Roth, German A

    2015-01-01

    Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease that mimics many of the clinical and pathological features of multiple sclerosis. We have previously described a significant diminution in the GABAergic regulation of glutamate release from synaptosomes of EAE rats isolated during the acute stage of the disease. In order to explore the possible metabolic pathways responsible for this alteration, in this work we evaluate the direct effect of different GABAergic agonists on the glutamate release and concomitant synapsin I phosphorylation in synaptosomes from the frontal cortex of control and EAE animals. The results show that GABA as well as the GABA receptor agonists Muscimol (GABAA agonist) and Baclofen (GABAB agonist) caused a decrease in glutamate release in control rats paralleled by a similar reduction in synapsin I phosphorylation. Meanwhile synaptosomes from EAE animals are responsive only to Baclofen with respect to nontreated EAE synaptosomes, since glutamate release from the synaptosomes treated with Muscimol was similar to that observed in EAE rat synaptosomes which was already reduced as consequence of the disease. In the case of the benzodiazepines Diazepam and Clonazepam (GABAA allosteric agonists), both of them induced a reduction in glutamate release in synaptosomes from the CFA rats, effect that was only observed in synaptosomes of EAE rats treated with Clonazepam. In all cases both benzodiazepines showed a higher effect on synapsin I phosphorylation than in glutamate release. These results indicate that the extent of GABAergic modulation of presynaptic terminals depends on the type of agonist employed and this regulation is altered in the frontal cortex during the acute phase of EAE with respect to control animals. PMID:26631092

  13. Estrogen receptor agonists alleviate cardiac and renal oxidative injury in rats with renovascular hypertension.

    PubMed

    Özdemir Kumral, Zarife Nigâr; Kolgazi, Meltem; Üstünova, Savaş; Kasımay Çakır, Özgür; Çevik, Özge Dağdeviren; Şener, Göksel; Yeğen, Berrak Ç

    2016-01-01

    Although endogenous estrogen is known to offer cardiac and vascular protection, the involvement of estrogen receptors in mediating the protective effect of estrogen on hypertension-induced cardiovascular and renal injury is not fully explained. We aimed to investigate the effects of estrogen receptor (ER) agonists on oxidative injury, cardiovascular and renal functions of rats with renovascular hypertension (RVH). Female Sprague-Dawley rats were randomly divided as control and RVH groups, and RVH groups had either ovariectomy (OVX) or sham-OVX. Sham-OVX-RVH and OVX-RVH groups received either ERβ agonist diarylpropiolnitrile (1 mg/kg/day) or ERα agonist propyl pyrazole triol (1 mg/kg/day) for 6 weeks starting at the third week following the surgery. At the end of the 9(th) week, systolic blood pressures were recorded, cardiac functions were determined, and the contraction/relaxation responses of aortic rings were obtained. Serum creatinine levels, tissue malondialdehyde, glutathione, superoxide dismutase, catalase levels, and myeloperoxidase activity in heart and kidney samples were analyzed, and Na(+), K(+)-ATPase activity was measured in kidney samples. In both sham-OVX and OVX rats, both agonists reduced blood pressure and reversed the impaired contractile performance of the heart, while ERβ agonist improved renal functions in both the OVX and non-OVX rats. Both agonists reduced neutrophil infiltration, lipid peroxidation, and elevated antioxidant levels in the heart, but a more ERβ-mediated protective effect was observed in the kidney. Our data suggest that activation of ERβ might play a role in preserving the function of the stenotic kidney and delaying the progression of renal injury, while both receptors mediate similar cardioprotective effects. PMID:27399230

  14. Early postnatal stress alters place conditioning to both mu- and kappa-opioid agonists.

    PubMed

    Michaels, Clifford C; Holtzman, Stephen G

    2008-04-01

    Clinical literature has established a link between early childhood incidents of neglect and trauma and adult problems with substance abuse. In rats, such early life stress has been modeled using a maternal separation (MS) paradigm in which rat pups were removed from their mothers for a few hours daily during the first two postnatal weeks. In this study, we used the MS model to investigate the effects of early postnatal stress on place conditioning to both mu- and kappa-opioid agonists in male and female Long-Evans rats. Offspring of both rearing conditions [MS or nonhandled (NH)] were conditioned using a biased procedure to saline, the mu-opioid agonist morphine (3.0, 5.6, and 10 mg/kg s.c.), or the kappa-opioid agonist spiradoline (0.3, 1.0, and 3.0 mg/kg) for 3 days, followed by a drug-free place-conditioning test 24 h later. Saline was administered in the morning, 30 min before confinement in one compartment, whereas morphine or spiradoline was administered in a similar manner 6 h later in the opposite compartment. MS offspring spent significantly more time in the morphine-paired compartment than NH offspring, indicating a greater place preference for the mu-opioid agonist. In the case of spiradoline, NH offspring spent significantly less time in the spiradoline-paired compartment, indicating a greater aversion to the kappa-opioid agonist in these animals than in MS offspring. These findings indicate that early postnatal stress can significantly alter the rewarding or aversive value of mu- and kappa-opioid agonists when measured using place conditioning. PMID:18203949

  15. Diabetogenic effect of a series of tricyclic delta opioid agonists structurally related to cyproheptadine.

    PubMed

    Codd, Ellen E; Baker, Judith; Brandt, Michael R; Bryant, Stewart; Cai, Chaozhong; Carson, John R; Chevalier, Kristen M; Colburn, Raymond W; Coogan, Timothy P; Dax, Scott L; Decorte, Bart; Kemmerer, Michael; Legrand, Edmund K; Lenhard, James M; Leone, Angelique M; Lin, Ling; Mabus, John R; McDonnell, Mark E; McMillian, Michael K; McNally, James J; Stone, Dennis J; Wang, Charles Y; Zhang, Sui-Po; Flores, Christopher M

    2010-10-01

    The unexpected observation of a hyperglycemic effect of some tricycle-based delta opioid receptor (DOR) agonists led to a series of studies to better understand the finding. Single administration of two novel tricyclic DOR agonists dose dependently elevated rat plasma glucose levels; 4-week toxicology studies confirmed the hyperglycemic finding and further revealed pancreatic β-cell hypertrophy, including vacuole formation, as well as bone dysplasia and Harderian gland degeneration with regeneration. Similar diabetogenic effects were observed in dog. A review of the literature on the antiserotonergic and antihistaminergic drug cyproheptadine (CPH) and its metabolites revealed shared structural features as well as similar hyperglycemic effects to the present series of DOR agonists. To further evaluate these effects, we established an assay measuring insulin levels in the rat pancreatic β-cell-derived RINm5F cell line, extensively used to study CPH and its metabolites. Like CPH, the initial DOR agonists studied reduced RINm5F cell insulin levels in a concentration-dependent manner. Importantly, compound DOR potency did not correlate with the insulin-reducing potency. Furthermore, the RINm5F cell insulin results correlated with the diabetogenic effect of the compounds in a 5-day mouse study. The RINm5F cell insulin assay enabled the identification of aryl-aryl-amine DOR agonists that lacked an insulin-reducing effect and did not elevate blood glucose in repeated dosing studies conducted over a suprapharmacologic dose range. Thus, not only did the RINm5F cell assay open a path for the further discovery of DOR agonists lacking diabetogenic potential but also it established a reliable, economical, and high-throughput screen for such potential, regardless of chemotype or target pharmacology. The present findings also suggest a mechanistic link between the toxicity observed here and that underlying Wolcott-Rallison Syndrome.

  16. Ligand-based receptor tyrosine kinase partial agonists: New paradigm for cancer drug discovery?

    PubMed Central

    Riese, David J.

    2010-01-01

    Introduction Receptor tyrosine kinases (RTKs) are validated targets for oncology drug discovery and several RTK antagonists have been approved for the treatment of human malignancies. Nonetheless, the discovery and development of RTK antagonists has lagged behind the discovery and development of agents that target G-protein coupled receptors. In part, this is because it has been difficult to discover analogs of naturally-occurring RTK agonists that function as antagonists. Areas covered Here we describe ligands of ErbB receptors that function as partial agonists for these receptors, thereby enabling these ligands to antagonize the activity of full agonists for these receptors. We provide insights into the mechanisms by which these ligands function as antagonists. We discuss how information concerning these mechanisms can be translated into screens for novel small molecule- and antibody-based antagonists of ErbB receptors and how such antagonists hold great potential as targeted cancer chemotherapeutics. Expert opinion While there have been a number of important key findings into this field, the identification of the structural basis of ligand functional specificity is still of the greatest importance. While it is true that, with some notable exceptions, peptide hormones and growth factors have not proven to be good platforms for oncology drug discovery; addressing the fundamental issues of antagonistic partial agonists for receptor tyrosine kinases has the potential to steer oncology drug discovery in new directions. Mechanism based approaches are now emerging to enable the discovery of RTK partial agonists that may antagonize both agonist-dependent and –independent RTK signaling and may hold tremendous promise as targeted cancer chemotherapeutics. PMID:21532939

  17. PPARγ Agonists Promote Oligodendrocyte Differentiation of Neural Stem Cells by Modulating Stemness and Differentiation Genes

    PubMed Central

    Kanakasabai, Saravanan; Pestereva, Ecaterina; Chearwae, Wanida; Gupta, Sushil K.; Ansari, Saif; Bright, John J.

    2012-01-01

    Neural stem cells (NSCs) are a small population of resident cells that can grow, migrate and differentiate into neuro-glial cells in the central nervous system (CNS). Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear receptor transcription factor that regulates cell growth and differentiation. In this study we analyzed the influence of PPARγ agonists on neural stem cell growth and differentiation in culture. We found that in vitro culture of mouse NSCs in neurobasal medium with B27 in the presence of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) induced their growth and expansion as neurospheres. Addition of all-trans retinoic acid (ATRA) and PPARγ agonist ciglitazone or 15-Deoxy-Δ12,14-Prostaglandin J2 (15d-PGJ2) resulted in a dose-dependent inhibition of cell viability and proliferation of NSCs in culture. Interestingly, NSCs cultured with PPARγ agonists, but not ATRA, showed significant increase in oligodendrocyte precursor-specific O4 and NG2 reactivity with a reduction in NSC marker nestin, in 3–7 days. In vitro treatment with PPARγ agonists and ATRA also induced modest increase in the expression of neuronal β-III tubulin and astrocyte-specific GFAP in NSCs in 3–7 days. Further analyses showed that PPARγ agonists and ATRA induced significant alterations in the expression of many stemness and differentiation genes associated with neuro-glial differentiation in NSCs. These findings highlight the influence of PPARγ agonists in promoting neuro-glial differentiation of NSCs and its significance in the treatment of neurodegenerative diseases. PMID:23185633

  18. Structural insights into selective agonist actions of tamoxifen on human Estrogen Receptor alpha

    PubMed Central

    Chakraborty, Sandipan; Biswas, P. K.

    2014-01-01

    Tamoxifen, an anti-estrogenic ligand in breast tissues and being used as a first-line treatment in ER-positive breast cancers, is found to develop resistance followed by resumption of growth of the tumor in about 30% of cases. Whether tamoxifen starts assisting in proliferation in such cases or there exists any ligand-independent pathways to transcription is not fully understood; also, no ERα mutants have been detected so far which could lead to tamoxifen resistance. Performing in-silico conformational analysis of ERα ligand binding domain, in the absence and presence of selective agonist (Diethylstilbestrol; DES), antagonist (Faslodex; ICI), and SERM (4-hydroxy tamoxifen; 4-OHT) ligands, we elucidated ligand-responsive structural modulations of ERα-LBD dimer in their agonist and antagonist complexes and address the issue of “tamoxifen resistance”. We found DES and ICI to stabilize the dimer in their agonist and antagonist conformations, respectively. The ERα-LBD dimer without the presence of any bound ligand also leads to a stable structure in agonist conformation. However, the binding of 4-OHT to antagonist structure is found to lead to a flexible conformation allowing the protein visiting conformations populated by agonists as are evident from principal component analysis and radius of gyration plots. Further, the relaxed conformations of the 4-OHT bound protein is found to exhibit a diminished size of the co-repressor binding pocket at LBD, thus signaling a partial blockage of the co-repressor binding motif. Thus, the ability of 4-OHT bound ERα-LBD to assume flexible conformations visited by agonists and reduced co-repressor binding surface at LBD provide crucial structural insights into tamoxifen-resistance complementing our existing understanding. PMID:25060147

  19. Synergistic teratogenic effects induced by retinoids in mice by coadministration of a RARalpha- or RARgamma-selective agonist with a RXR-selective agonist.

    PubMed

    Elmazar, M M; Rühl, R; Nau, H

    2001-01-01

    To study the interaction of retinoid-induced limb defects and cleft palate on day 11 of gestation, a RXR-selective agonist (AGN191701, an arylpropenyl-thiophene-carboxylic acid derivative, 20 mg/kg orally) was coadministered with a RARalpha-agonist (Am580, an arylcarboxamidobenzoic acid derivative, 5 mg/kg orally) to NMRI mice. AGN191701 was neither fetotoxic nor teratogenic at the dose used but potentiated Am580-induced limb defects and cleft palate and prevented Am580-induced fetal weight retardation. These results suggest that Am580-induced limb defects and probably cleft palate on day 11 of gestation may be mediated via RARalpha-RXR heterodimerization, particularly in the absence of toxicokinetic interactions. AGN191701 was also coadministered with a RARgamma-agonist (CD437, an adamantyl-hydroxyphenyl naphthoic acid derivative, 15 mg/kg orally) on days 8 and 11 of gestation to investigate which CD437-induced defects are mediated via RARgamma-RXR heterodimerization. On day 8 of gestation, AGN191701 potentiated CD437-induced embryolethality, exencephaly, spina bifida aperta, cleft palate, and tail defects, as well as visceral and skeletal defects, but not micrognathia. On day 11 of gestation, the incidence of CD437-induced cleft palate and limb defects was also potentiated when coadministered with the RXR agonist. These results suggest that synergistic teratogenic effects can be induced by coadministration of two receptor-selective retinoids, indicating the importance of RARalpha-RXR and RARgamma-RXR heterodimers in producing structural defects during organogenesis.

  20. The role of inhaled long-acting beta-2 agonists in the management of asthma.

    PubMed Central

    Kelly, H. William; Harkins, Michelle S.; Boushey, Homer

    2006-01-01

    The role of inhaled beta-2 agonists in the management of asthma has changed significantly over the last several years. This review outlines the most recent understanding of the pathophysiology of asthma and the studies that define the roles that both short- and long-acting beta-2 agonists play in therapy for this disease. A concentration on the clinical pharmacology and genetic implications for clinical use of this class of drugs in accordance with the national and international guidelines are described. PMID:16532973

  1. The CRTH2 agonist Pyl A prevents lipopolysaccharide-induced fetal death but induces preterm labour

    PubMed Central

    Sykes, Lynne; Herbert, Bronwen R; MacIntyre, David A; Hunte, Emma; Ponnampalam, Sathana; Johnson, Mark R; Teoh, Tiong G; Bennett, Phillip R

    2013-01-01

    We have previously demonstrated that the anti-inflammatory prostaglandin 15-deoxy-Δ 12,14-prostaglandin J2 (15dPGJ2) delays inflammation-induced preterm labour in the mouse and improves pup survival through the inhibition of nuclear factor-κB (NF-κB) by a mechanism yet to be elucidated. 15dPGJ2 is an agonist of the second prostaglandin D2 receptor, chemoattractant receptor homologous to the T helper 2 cell (CRTH2). In human T helper cells CRTH2 agonists induce the production of the anti-inflammatory interleukins IL-10 and IL-4. We hypothesized that CRTH2 is involved in the protective effect of 15dPGJ2 in inflammation-induced preterm labour in the murine model. We therefore studied the effects of a specific small molecule CRTH2 agonist on preterm labour and pup survival. An intrauterine injection of lipopolysaccharide (LPS) was administered to CD1 mice at embryonic day 16, ± CRTH2 agonist/vehicle controls. Mice were killed at 4.5 hr to assess fetal wellbeing and to harvest myometrium and pup brain for analysis of NF-κB, and T helper type 1/2 interleukins. To examine the effects of the CRTH2 agonist on LPS-induced preterm labour, mice were allowed to labour spontaneously. Direct effects of the CRTH2 agonist on uterine contractility were examined ex vivo on contracting myometrial strips. The CRTH2 agonist increased fetal survival from 20 to 100% in LPS-treated mice, and inhibited circular muscle contractility ex vivo. However, it augmented LPS-induced labour and significantly increased myometrial NF-κB, IL-1β, KC-GRO, interferon-γ and tumour necrosis factor-α. This suggests that the action of 15dPGJ2 is not via CRTH2 and therefore small molecule CRTH2 agonists are not likely to be beneficial for the prevention of inflammation-induced preterm labour. PMID:23374103

  2. Beta 2-adrenergic agonist as adjunct therapy to levodopa in Parkinson's disease.

    PubMed

    Alexander, G M; Schwartzman, R J; Nukes, T A; Grothusen, J R; Hooker, M D

    1994-08-01

    We studied the effect of the beta 2-adrenergic agonist albuterol on Parkinson's disease (PD) patients receiving chronic levodopa treatment. The albuterol-treated patients demonstrated reduced parkinsonian symptoms and an increased ability to tap their index finger between two points 20 cm apart, and were able to perform a "walk test" in 70% of their control time. Three patients currently on chronic albuterol therapy still show amelioration of their parkinsonian symptoms, and two have reduced their daily levodopa dose. This study suggests that beta 2-adrenergic agonists as adjunct therapy to levodopa may be beneficial in PD.

  3. Potent complement C3a receptor agonists derived from oxazole amino acids: Structure-activity relationships.

    PubMed

    Singh, Ranee; Reed, Anthony N; Chu, Peifei; Scully, Conor C G; Yau, Mei-Kwan; Suen, Jacky Y; Durek, Thomas; Reid, Robert C; Fairlie, David P

    2015-12-01

    Potent ligands for the human complement C3a receptor (C3aR) were developed from the almost inactive tripeptide Leu-Ala-Arg corresponding to the three C-terminal residues of the endogenous peptide agonist C3a. The analogous Leu-Ser-Arg was modified by condensing the serine side chain with the leucine carbonyl with elimination of water to form leucine-oxazole-arginine. Subsequent elaboration with a variety of N-terminal amide capping groups produced agonists as potent as human C3a itself in stimulating Ca(2+) release from human macrophages. Structure-activity relationships are discussed.

  4. Synthesis and pharmacological characterization of beta2-adrenergic agonist enantiomers: zilpaterol.

    PubMed

    Kern, Christopher; Meyer, Thorsten; Droux, Serge; Schollmeyer, Dieter; Miculka, Christian

    2009-03-26

    The beta-adrenergic agonist 1 (zilpaterol) is used as production enhancer in cattle. Binding experiments of separated enantiomers on recombinant human beta(2)-adrenergic and mu-opioid receptors and functional studies showed that the (-)-1 enantiomer accounts for essentially all the beta(2)-adrenergic agonist activity and that it exhibits less affinity toward the mu-opioid receptor than (+)-1, which is a mu-opioid receptor antagonist. X-ray crystallography revealed the absolute configuration of (-)-1 to be 6R,7R.

  5. Thrombopoietin receptor agonists: a new immune modulatory strategy in immune thrombocytopenia?

    PubMed

    Schifferli, Alexandra; Kühne, Thomas

    2016-04-01

    In 2008, new drugs that mimic the effects of thrombopoietin became available for the treatment of primary immune thrombocytopenia, eg, romiplostim and eltrombopag. These drugs activate the thrombopoietin receptor, stimulate the production of megakaryocytes, and increase the production of platelets. Important clinical observation has been gained, such as unexpected long-term remission after stopping thrombopoietin receptor agonists. The pathophysiology of this unforeseen cure is currently the subject of discussion and is investigated in clinical trials and laboratory research projects. Here we evaluate the different hypotheses on how thrombopoietin receptor agonists can affect the immune system, particularly the induction of tolerance, and by which mechanisms this may be achieved. PMID:27312161

  6. Dimethyl-diphenyl-propanamide derivatives as nonsteroidal dissociated glucocorticoid receptor agonists.

    PubMed

    Yang, Bingwei V; Weinstein, David S; Doweyko, Lidia M; Gong, Hua; Vaccaro, Wayne; Huynh, Tram; Xiao, Hai-Yun; Doweyko, Arthur M; McKay, Lorraine; Holloway, Deborah A; Somerville, John E; Habte, Sium; Cunningham, Mark; McMahon, Michele; Townsend, Robert; Shuster, David; Dodd, John H; Nadler, Steven G; Barrish, Joel C

    2010-12-01

    A series of 2,2-dimethyl-3,3-diphenyl-propanamides as novel glucocorticoid receptor modulators is reported. SAR exploration led to the identification of 4-hydroxyphenyl propanamide derivatives displaying good agonist activity in GR-mediated transrepression assays and reduced agonist activity in GR-mediated transactivation assays. Compounds 17 and 30 showed anti-inflammatory activity comparable to prednisolone in the rat carrageenan-induced paw edema model, with markedly decreased side effects with regard to increases in blood glucose and expression of hepatic tyrosine aminotransferase. A hypothetical binding mode accounting for the induction of the functional activity by a 4-hydroxyl group is proposed. PMID:21073190

  7. Synthesis and SAR of aminothiazole fused benzazepines as selective dopamine D2 partial agonists.

    PubMed

    Urbanek, Rebecca A; Xiong, Hui; Wu, Ye; Blackwell, William; Steelman, Gary; Rosamond, Jim; Wesolowski, Steven S; Campbell, James B; Zhang, Minli; Brockel, Becky; Widzowski, Daniel V

    2013-01-15

    Dopamine (D(2)) partial agonists (D2PAs) have been regarded as a potential treatment for schizophrenia patients with expected better side effect profiles than currently marketed antipsychotics. Herein we report the synthesis and SAR of a series of aminothiazole fused benzazepines as selective D(2) partial agonists. These compounds have good selectivity, CNS drug-like properties and tunable D(2) partial agonism. One of the key compounds, 8h, has good in vitro/in vivo ADME characteristics, and is active in a rat amphetamine-induced locomotor activity model. PMID:23237836

  8. Biperiden enhances L-DOPA methyl ester and dopamine D(l) receptor agonist SKF-82958 but antagonizes D(2)/D(3) receptor agonist rotigotine antihemiparkinsonian actions.

    PubMed

    Domino, Edward F; Ni, Lisong

    2008-12-01

    The effects of biperiden (0, 100, and 320 microg/kg), a selective muscarinic M(1)/M(4) receptor cholinergic antagonist, were studied alone and in combination with those of L-DOPA methyl ester (16.7 mg/kg), a selective dopamine D(1) receptor agonist SKF-82958 (74.8 microg/kg), or a selective D(2)/D(3) receptor agonist rotigotine (32 microg/kg) on circling behavior in MPTP induced hemiparkinsonian monkeys. The doses selected were given i.m. in approximately equieffective doses to produce contraversive circling. Biperiden alone with 5% dextrose vehicle produced a slight increase in contraversive circling in a dose related manner. When combined with L-DOPA methyl ester, it enhanced contraversive circling and decreased ipsiversive circling. When biperiden was combined with SKF-82958, contraversive circling also was enhanced and ipsiversive circling decreased. Exactly the opposite was observed with the combination of biperiden and rotigotine. The results indicate a dramatic difference in effects of a prototypic muscarinic M(1)/M(4) receptor cholinergic antagonist in combination with prototypic full dopamine D(1) or D(2)/D(3) receptor agonists. Biperiden interactions with L-DOPA methyl ester were more predominantly D(l) than D(2)/D(3) receptor-like in this animal model of hemiparkinsonism.

  9. New 4-Functionalized Glutamate Analogues Are Selective Agonists at Metabotropic Glutamate Receptor Subtype 2 or Selective Agonists at Metabotropic Glutamate Receptor Group III.

    PubMed

    Huynh, Tri H V; Erichsen, Mette N; Tora, Amélie S; Goudet, Cyril; Sagot, Emmanuelle; Assaf, Zeinab; Thomsen, Christian; Brodbeck, Robb; Stensbøl, Tine B; Bjørn-Yoshimoto, Walden E; Nielsen, Birgitte; Pin, Jean-Philippe; Gefflaut, Thierry; Bunch, Lennart

    2016-02-11

    The metabotropic glutamate (Glu) receptors (mGluRs) play key roles in modulating excitatory neurotransmission in the brain. In all, eight subtypes have been identified and divided into three groups, group I (mGlu1,5), group II (mGlu2,3), and group III (mGlu4,6-8). In this article, we present a L-2,4-syn-substituted Glu analogue, 1d, which displays selective agonist activity at mGlu2 over the remaining mGluR subtypes. A modeling study and redesign of the core scaffold led to the stereoselective synthesis of four new conformationally restricted Glu analogues, 2a-d. Most interestingly, 2a retained a selective agonist activity profile at mGlu2 (EC50 in the micromolar range), whereas 2c/2d were both selective agonists at group III, subtypes mGlu4,6,8. In general, 2d was 20-fold more potent than 2c and potently activated mGlu4,6,8 in the low-mid nanomolar range.

  10. Coordination Compounds of Strontium. Syntheses, Characterizations, and Crystal Structures of [Sr(u-ONc)(2)(HONc(4))]2 and Sr(5)(u(4)-O)(u(3)-ONep)(4)(u-ONep)(4)(HONep)(solv)(4) (ONc=O(2)CCH(2)CMe(3));Nep=CH(2)CMe(3); solv=tetrahydrofuran or 1-methyl-imida

    SciTech Connect

    Boyle, Timothy J.; Tafoya, Cory J.; Scott, Brian L.; Ziller, Joseph W.

    1999-07-21

    The authors have synthesized and characterized two novel Sr compounds: [Sr({mu}-ONc){sub 2}(HONc){sub 4}]{sub 2} (1, ONc = O{sub 2}CCH{sub 2}CMe{sub 3}), and Sr{sub 5}({mu}{sub 4}-O)({mu}{sub 3}-ONep){sub 4}({mu}-ONep){sub 4}(HONep)(solv){sub 4} [ONep = OCH{sub 2}CMe{sub 3}, solv = tetrahydrofuran (THF), 2a; 1-methyl-imidazole (MeIm), (2b)], that demonstrate increased solubility in comparison to the commercially available Sr precursors. The two metal centers of 1 share 4 unidentate bridging {mu}-ONc ligands and complete their octahedral geometry through the coordination of 4 monodentate terminal HONc ligands. The structure arrangement of the central core of 2a and b are identical, wherein 4 octahedral Sr atoms are arranged in a square geometry around a {mu}{sub 4}-O ligand. An additional 7-coordinated Sr atom sits directly atop the {mu}{sub 4}-O to form a square base pyramidal arrangement of the Sr atoms but the apical Sr-O distance is too long to be considered a bond. In solution, compound 1 is disrupted forming a monomer but 2a and b retain their structures.

  11. Infrared resonance Raman, and excitation profile studies of Os/sub 2/(O/sub 2/CCH/sub 3/)/sub 4/Cl/sub 2/ and Os/sub 2/(O/sub 2/CCD/sub 3/)/sub 4/Cl/sub 2/. The assignment of the osmium-osmium stretching vibration for a complex involving an osmium-osmium multiple bond

    SciTech Connect

    Clark, R.J.H.; Hempleman, A.J.; Tocher, D.A.

    1988-08-31

    Extensive Raman studies (1525-40 cm/sup /minus/1/) of Os/sub 2/(O/sub 2/CCH/sub 3/)/sub 4/Cl/sub 2/ have led to the identification of the three strong bands, /nu//sub 1/, /nu//sub 2/, and /nu//sub 3/, at 229, 393, and 292 cm/sup /minus/1/ to the key skeletal stretching modes, /nu/(OsOs), /nu/(OsO), and /nu/(OsCl), respectively. Raman spectra of the complex at resonance with the intense electronic band at /lambda//sub max/ = 383 nm lead to the development of a six-membered overtone progression in /nu//sub 1/ as well as combination band progressions in /nu//sub 1/ based upon one quantum of either /nu//sub 2/ or /nu//sub 3/. This indicates that the principal structural change attendant upon excitation to the resonant state is along the OsOs coordinate. Fourier transform infrared spectra (3500-40 cm/sup /minus/1/) have also been obtained. Acetate deuteriation provides conclusive evidence for many of the infrared and Raman band assignments. The study provides the first firm identification of /nu/(OsOs) for a multiply bonded species.

  12. MUC-1 Tumor Antigen Agonist Epitopes for Enhancing T-cell Responses to Human Tumors | NCI Technology Transfer Center | TTC

    Cancer.gov

    Scientists at NIH have identified 7 new agonist epitopes of the MUC-1 tumor associated antigen. Compared to their native epitope counterparts, peptides reflecting these agonist epitopes have been shown to enhance the generation of human tumor cells, which in turn have a greater ability to kill human tumor cells endogenously expressing the native MUC-1 epitope.

  13. Effect of beta-ADrenergic Agonist on Cyclic AMP Synthesis in Chicken Skeletal Muscle Cells in Culture

    NASA Technical Reports Server (NTRS)

    Young, R. B.; Bridge, K. Y.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Because it seems logical that these agonists exert their action on muscle through stimulation of cAMP synthesis, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate cAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of cAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of cAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax levels were approximately 15-fold weaker than isoproterenol in stimulating the rate of cAMP synthesis. In addition, the EC50 values for isoproterenol, cimaterol, clenbuterol, epinephrine, and albuterol were 360 nM, 630 nM, 900 nM, 2,470 nM, and 3,650 nM, respectively. Finally, dose response curves show that the concentrations of cimaterol and clenbuterol in culture media at concentrations known to cause significant muscle hypertrophy in animals had no detectable effect on stimulation of CAMP accumulation in chicken skeletal muscle cells.

  14. Self-administration of agonists selective for dopamine D2, D3, and D4 receptors by rhesus monkeys.

    PubMed

    Koffarnus, Mikhail N; Collins, Gregory T; Rice, Kenner C; Chen, Jianyong; Woods, James H; Winger, Gail

    2012-08-01

    Dopamine receptor mechanisms are believed to play a role in the reinforcing effects of cocaine and other drugs of abuse. The lack of receptor-selective agonists has made it difficult to determine the role of the individual dopamine receptors in mediating these reinforcing effects. In this study, rhesus monkeys with a history of intravenous cocaine self-administration were tested for the reinforcing effects of several D(3)-preferring agonists, a D(2)-preferring agonist, and a D(4) agonist. The D(2)-preferring agonist did not maintain responding in any monkeys, and the D(4) agonist was self-administered at low rates, just above those maintained by saline, in one monkey. The D(3)-preferring agonists were self-administered by approximately half of the animals, although at lower rates than cocaine. These results indicate that the apparent limited reinforcing effectiveness of D(2)-like agonists requires activity at D(3) receptors. Previous data from this laboratory and others also suggest that these drugs may not serve as reinforcers directly; the behavior may be maintained by response-contingent delivery of stimuli previously paired with cocaine. The ability of drug-related stimuli to maintain responding apparently differs among monkeys and other organisms, and may be related to individual differences in drug-taking behavior in humans. PMID:22785383

  15. Multifunctional Antibody Agonists Targeting Glucagon-like Peptide-1, Glucagon, and Glucose-Dependent Insulinotropic Polypeptide Receptors.

    PubMed

    Wang, Ying; Du, Jintang; Zou, Huafei; Liu, Yan; Zhang, Yuhan; Gonzalez, Jose; Chao, Elizabeth; Lu, Lucy; Yang, Pengyu; Parker, Holly; Nguyen-Tran, Van; Shen, Weijun; Wang, Danling; Schultz, Peter G; Wang, Feng

    2016-09-26

    Glucagon-like peptide-1 (GLP-1) receptor (GLP-1R), glucagon (GCG) receptor (GCGR), and glucose-dependent insulinotropic polypeptide (GIP, also known as gastric inhibitory polypeptide) receptor (GIPR), are three metabolically related peptide hormone receptors. A novel approach to the generation of multifunctional antibody agonists that activate these receptors has been developed. Native or engineered peptide agonists for GLP-1R, GCGR, and GIPR were fused to the N-terminus of the heavy chain or light chain of an antibody, either alone or in pairwise combinations. The fusion proteins have similar in vitro biological activities on the cognate receptors as the corresponding peptides, but circa 100-fold longer plasma half-lives. The GLP-1R mono agonist and GLP-1R/GCGR dual agonist antibodies both exhibit potent effects on glucose control and body weight reduction in mice, with the dual agonist antibody showing enhanced activity in the latter. PMID:27595986

  16. A Robotic BG1Luc Reporter Assay to Detect Estrogen Receptor Agonists

    PubMed Central

    Stoner, Matthew A.; Yang, Chun Z.; Bittner, George D.

    2014-01-01

    Endocrine disrupting chemicals with estrogenic activity (EA) have been associated with various adverse health effects. US agencies (ICCVAM/NICEATM) tasked to assess in vitro transcription activation assays to detect estrogenic receptor (ER) agonists for EA have recently validated a BG1Luc assay in manual format, but prefer robotic formats. We have developed a robotic BG1Luc EA assay to detect EA that demonstrated 100% concordance with ICCVAM meta-analyses and ICCVAM BG1Luc results in manual format for 27 ICCVAM test substances, i.e. no false negatives or false positives. This robotic assay also consistently assessed other, more problematic ICCVAM test substances such as clomiphene citrate, L-thyroxin, and tamoxifen. Agonist responses using this robotic BG1Luc assay were consistently inhibited by the ER antagonist ICI 182,780, confirming that agonist responses were due to binding to ERs rather than to a non-specific agonist response. This robotic assay also detected EA in complex mixtures of substances such as extracts of personal care products, plastic resins or plastic consumer products. This robotic BG1Luc assay had at least as high accuracy and greater sensitivity and repeatability when compared to its manual version or to the other ICCVAM/OECD validated assays for EA (manual BG1Luc and CERI). PMID:24747293

  17. Incretin-like effects of small molecule trace amine-associated receptor 1 agonists

    PubMed Central

    Raab, Susanne; Wang, Haiyan; Uhles, Sabine; Cole, Nadine; Alvarez-Sanchez, Ruben; Künnecke, Basil; Ullmer, Christoph; Matile, Hugues; Bedoucha, Marc; Norcross, Roger D.; Ottaway-Parker, Nickki; Perez-Tilve, Diego; Conde Knape, Karin; Tschöp, Matthias H.; Hoener, Marius C.; Sewing, Sabine

    2015-01-01

    Objective Type 2 diabetes and obesity are emerging pandemics in the 21st century creating worldwide urgency for the development of novel and safe therapies. We investigated trace amine-associated receptor 1 (TAAR1) as a novel target contributing to the control of glucose homeostasis and body weight. Methods We investigated the peripheral human tissue distribution of TAAR1 by immunohistochemistry and tested the effect of a small molecule TAAR1 agonist on insulin secretion in vitro using INS1E cells and human islets and on glucose tolerance in C57Bl6, and db/db mice. Body weight effects were investigated in obese DIO mice. Results TAAR1 activation by a selective small molecule agonist increased glucose-dependent insulin secretion in INS1E cells and human islets and elevated plasma PYY and GLP-1 levels in mice. In diabetic db/db mice, the TAAR1 agonist normalized glucose excursion during an oral glucose tolerance test. Sub-chronic treatment of diet-induced obese (DIO) mice with the TAAR1 agonist resulted in reduced food intake and body weight. Furthermore insulin sensitivity was improved and plasma triglyceride levels and liver triglyceride content were lower than in controls. Conclusions We have identified TAAR1 as a novel integrator of metabolic control, which acts on gastrointestinal and pancreatic islet hormone secretion. Thus TAAR1 qualifies as a novel and promising target for the treatment of type 2 diabetes and obesity. PMID:26844206

  18. Identification of a New Type of Covalent PPARγ Agonist using a Ligand-Linking Strategy.

    PubMed

    Ohtera, Anna; Miyamae, Yusaku; Yoshida, Kotaro; Maejima, Kazuhiro; Akita, Toru; Kakizuka, Akira; Irie, Kazuhiro; Masuda, Seiji; Kambe, Taiho; Nagao, Masaya

    2015-12-18

    Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated transcription factor that plays an important role in adipogenesis and glucose metabolism. The ligand-binding pocket (LBP) of PPARγ has a large Y-shaped cavity with multiple subpockets where multiple ligands can simultaneously bind and cooperatively activate PPARγ. Focusing on this unique property of the PPARγ LBP, we describe a novel two-step cell-based strategy to develop PPARγ ligands. First, a combination of ligands that cooperatively activates PPARγ was identified using a luciferase reporter assay. Second, hybrid ligands were designed and synthesized. For proof of concept, we focused on covalent agonists, which activate PPARγ through a unique activation mechanism regulated by a covalent linkage with the Cys285 residue in the PPARγ LBP. Despite their biological significance and pharmacological potential, few covalent PPARγ agonists are known except for endogenous fatty acid metabolites. With our strategy, we determined that plant-derived cinnamic acid derivatives cooperatively activated PPARγ by combining with GW9662, an irreversible antagonist. GW9662 covalently reacts with the Cys285 residue. A docking study predicted that a cinnamic acid derivative can bind to the open cavity in GW9662-bound PPARγ LBP. On the basis of the putative binding mode, structures of both ligands were linked successfully to create a potent PPARγ agonist, which enhanced the transactivation potential of PPARγ at submicromolar levels through covalent modification of Cys285. Our approach could lead to the discovery of novel high-potency PPARγ agonists.

  19. Pyridopyrimidine based cannabinoid-1 receptor inverse agonists: Synthesis and biological evaluation.

    PubMed

    Debenham, John S; Madsen-Duggan, Christina B; Wang, Junying; Tong, Xinchun; Lao, Julie; Fong, Tung M; Schaeffer, Marie-Therese; Xiao, Jing Chen; Huang, Cathy C R-R; Shen, Chun-Pyn; Sloan Stribling, D; Shearman, Lauren P; Strack, Alison M; Euan Macintyre, D; Hale, Jeffrey J; Walsh, Thomas F

    2009-05-01

    The synthesis, SAR and binding affinities are described for cannabinoid-1 receptor (CB1R) specific inverse agonists based on pyridopyrimidine and heterotricyclic scaffolds. Food intake and pharmacokinetic evaluation of several of these compounds indicate that they are effective orally active modulators of CB1R.

  20. Inhibitory GTP binding protein G/sub i/ regulates US -adrenoceptor affinity towards US -agonists

    SciTech Connect

    Marbach, I.; Levitzki, A.

    1987-05-01

    Treatment of S-49 lymphoma cell membranes with pertussis toxin (PT) causes a three-fold reduction of US -adrenoceptor (US AR) affinity towards isoproterenol. A similar treatment with cholera toxin (CT) does not cause such a modulation. The effects were studied by the detailed analysis of SVI-cyanopindolol (CYP) binding curves in the absence and presence of increasing agonist concentrations. Thus, the authors were able to compare in detail the effects of G/sub s/ and G/sub i/ on the agonist-associated state of the US AR. In contrast to these findings, PT treatment does not have any effect on the displacement of SVI-CYP by (-)isoproterenol. These results demonstrate that the inhibitory GTP protein G/sub i/ modulates the US AR affinity towards US -agonists. This might be due to the association of G/sub i/ with the agonist-bound US AR x G/sub s/ x C complex within the membrane. This hypothesis, as well as others, is under investigation.

  1. Agonist-Mediated Activation of STING Induces Apoptosis in Malignant B Cells.

    PubMed

    Tang, Chih-Hang Anthony; Zundell, Joseph A; Ranatunga, Sujeewa; Lin, Cindy; Nefedova, Yulia; Del Valle, Juan R; Hu, Chih-Chi Andrew

    2016-04-15

    Endoplasmic reticulum (ER) stress responses through the IRE-1/XBP-1 pathway are required for the function of STING (TMEM173), an ER-resident transmembrane protein critical for cytoplasmic DNA sensing, IFN production, and cancer control. Here we show that the IRE-1/XBP-1 pathway functions downstream of STING and that STING agonists selectively trigger mitochondria-mediated apoptosis in normal and malignant B cells. Upon stimulation, STING was degraded less efficiently in B cells, implying that prolonged activation of STING can lead to apoptosis. Transient activation of the IRE-1/XBP-1 pathway partially protected agonist-stimulated malignant B cells from undergoing apoptosis. In Eμ-TCL1 mice with chronic lymphocytic leukemia, injection of the STING agonist 3'3'-cGAMP induced apoptosis and tumor regression. Similarly efficacious effects were elicited by 3'3'-cGAMP injection in syngeneic or immunodeficient mice grafted with multiple myeloma. Thus, in addition to their established ability to boost antitumoral immune responses, STING agonists can also directly eradicate malignant B cells. Cancer Res; 76(8); 2137-52. ©2016 AACR. PMID:26951929

  2. Agonistic aptamer to the insulin receptor leads to biased signaling and functional selectivity through allosteric modulation.

    PubMed

    Yunn, Na-Oh; Koh, Ara; Han, Seungmin; Lim, Jong Hun; Park, Sehoon; Lee, Jiyoun; Kim, Eui; Jang, Sung Key; Berggren, Per-Olof; Ryu, Sung Ho

    2015-09-18

    Due to their high affinity and specificity, aptamers have been widely used as effective inhibitors in clinical applications. However, the ability to activate protein function through aptamer-protein interaction has not been well-elucidated. To investigate their potential as target-specific agonists, we used SELEX to generate aptamers to the insulin receptor (IR) and identified an agonistic aptamer named IR-A48 that specifically binds to IR, but not to IGF-1 receptor. Despite its capacity to stimulate IR autophosphorylation, similar to insulin, we found that IR-A48 not only binds to an allosteric site distinct from the insulin binding site, but also preferentially induces Y1150 phosphorylation in the IR kinase domain. Moreover, Y1150-biased phosphorylation induced by IR-A48 selectively activates specific signaling pathways downstream of IR. In contrast to insulin-mediated activation of IR, IR-A48 binding has little effect on the MAPK pathway and proliferation of cancer cells. Instead, AKT S473 phosphorylation is highly stimulated by IR-A48, resulting in increased glucose uptake both in vitro and in vivo. Here, we present IR-A48 as a biased agonist able to selectively induce the metabolic activity of IR through allosteric binding. Furthermore, our study also suggests that aptamers can be a promising tool for developing artificial biased agonists to targeted receptors. PMID:26245346

  3. Profound and rapid reduction in body temperature induced by the melanocortin receptor agonists

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The melanocortin receptor 4 (MC4R) plays a major role in body weight regulation and its agonist MTII has been widely used to study the role of MC4Rs in energy expenditure promotion and feeding reduction. Unexpectedly, we observed that intraperitoneal (i.p.) administration of MTII induced a rapid red...

  4. Identification of novel multitargeted PPARα/γ/δ pan agonists by core hopping of rosiglitazone.

    PubMed

    Wang, Xue-Jiao; Zhang, Jun; Wang, Shu-Qing; Xu, Wei-Ren; Cheng, Xian-Chao; Wang, Run-Ling

    2014-01-01

    The thiazolidinedione class peroxisome proliferator-activated receptor gamma (PPARγ) agonists are restricted in clinical use as antidiabetic agents because of side effects such as edema, weight gain, and heart failure. The single and selective agonism of PPARγ is the main cause of these side effects. Multitargeted PPARα/γ/δ pan agonist development is the hot topic in the antidiabetic drug research field. In order to identify PPARα/γ/δ pan agonists, a compound database was established by core hopping of rosiglitazone, which was then docked into a PPARα/γ/δ active site to screen out a number of candidate compounds with a higher docking score and better interaction with the active site. Further, absorption, distribution, metabolism, excretion, and toxicity prediction was done to give eight compounds. Molecular dynamics simulation of the representative Cpd#1 showed more favorable binding conformation for PPARs receptor than the original ligand. Cpd#1 could act as a PPARα/γ/δ pan agonist for novel antidiabetic drug research. PMID:25422585

  5. Sphenoid wing meningioma progression after placement of a subcutaneous progesterone agonist contraceptive implant.

    PubMed

    Piper, J G; Follett, K A; Fantin, A

    1994-04-01

    A causal relationship between sex steroids and meningioma proliferation has long been suspected. We report a case of the clinical progression of a sphenoid wing meningioma after the placement of Norplant, a subcutaneous contraceptive implant containing levonorgestrel, a progesterone agonist. Although not proof of causation, this observation lends further credence to the importance of progesterone receptors in the growth and possible treatment of meningiomas.

  6. Nebulized PPARγ Agonists: A Novel Approach to Augment Neonatal Lung Maturation and Injury Repair

    PubMed Central

    Morales, Edith; Sakurai, Reiko; Husain, Sumair; Paek, Dave; Gong, Ming; Ibe, Basil; Li, Yishi; Husain, Maleha; Torday, John S.; Rehan, Virender K.

    2014-01-01

    BACKGROUND By stimulating lipofibroblast maturation, parenterally administered PPARγ agonists promote lung homeostasis and injury repair in the neonatal lung. In this study, we determined whether PPARγ agonists could be delivered effectively via nebulization to neonates, and whether this approach would also protect against hyperoxia-induced lung injury. METHODS One-day old Sprague-Dawley rat pups were administered PPARγ agonists rosiglitazone (RGZ, 3 mg/kg), pioglitazone (PGZ, 3 mg/kg), or the diluent, via nebulization every 24h; animals were exposed to 21% or 95% O2 for up to 72h. Twenty-four and 72h following initial nebulization, the pups were sacrificed for lung tissue and blood collection to determine markers of lung maturation, injury repair, and RGZ and PGZ plasma levels. RESULTS Nebulized RGZ and PGZ enhanced lung maturation in both males and females, as evidenced by the increased expression of markers of alveolar epithelial and mesenchymal maturation. This approach also protected against hyperoxia-induced lung injury, since hyperoxia-induced changes in bronchoalveolar lavage cell and protein contents and lung injury markers were all blocked by nebulized PGZ. CONCLUSIONS Nebulized PPARγ agonist administration promotes lung maturation and prevents neonatal hyperoxia-induced lung injury in both males and females. PMID:24488089

  7. Development of agonistic encounters in dominance hierarchy formation in juvenile crayfish.

    PubMed

    Sato, Daisuke; Nagayama, Toshiki

    2012-04-01

    We have characterized the behavioural patterns of crayfish during agonistic bouts between groups of crayfish of four different body lengths (9-19, 20-32, 41-48 and 69-75 mm) to characterize changes in the patterns of agonistic encounter during development. The behaviour of both dominant and subordinate animals was analysed by single frame measurement of video recordings. Behavioural acts that occurred during agonistic bouts were categorized as one of seven types: capture, fight, contact, approach, retreat, tailflip and neutral. Dominant-subordinate relationships were formed between juvenile crayfish as early as the third stage of development. Patterns of agonistic bouts to determine social hierarchy became more aggressive during development. The dominant-subordinate relationship was usually determined after contact in crayfish of less than 20 mm and 20-32 mm in length, while several bouts of fights were necessary for crayfish of 41-48 and 69-75 mm in length. Furthermore, social hierarchy was formed more rapidly in small crayfish. In larger animals, the number of approaches by dominant animals that promoted retreat in subordinate animals increased after the establishment of the winner-loser relationship. In smaller crayfish, in contrast, no measurable changes in these behaviour patterns were observed before and after the establishment of the winner-loser relationship. With increasing body size, the probability of tailflips decreased while that of retreats increased as the submissive behavioural act of subordinate animals.

  8. Discovery and characterization of novel small-molecule CXCR4 receptor agonists and antagonists

    PubMed Central

    Mishra, Rama K.; Shum, Andrew K.; Platanias, Leonidas C.; Miller, Richard J.; Schiltz, Gary E.

    2016-01-01

    The chemokine CXCL12 (SDF-1) and its cognate receptor CXCR4 are involved in a large number of physiological processes including HIV-1 infectivity, inflammation, tumorigenesis, stem cell migration, and autoimmune diseases. While previous efforts have identified a number of CXCR4 antagonists, there have been no small molecule agonists reported. Herein, we describe the identification of a novel series of CXCR4 modulators, including the first small molecules to display agonist behavior against this receptor, using a combination of structure- and ligand-based virtual screening. These agonists produce robust calcium mobilization in human melanoma cell lines which can be blocked by the CXCR4-selective antagonist AMD3100. We also demonstrate the ability of these new agonists to induce receptor internalization, ERK activation, and chemotaxis, all hallmarks of CXCR4 activation. Our results describe a new series of biologically relevant small molecules that will enable further study of the CXCR4 receptor and may contribute to the development of new therapeutics. PMID:27456816

  9. Environmental enrichment improves novel object recognition and enhances agonistic behavior in male mice.

    PubMed

    Mesa-Gresa, Patricia; Pérez-Martinez, Asunción; Redolat, Rosa

    2013-01-01

    Environmental enrichment (EE) is an experimental paradigm in which rodents are housed in complex environments containing objects that provide stimulation, the effects of which are expected to improve the welfare of these subjects. EE has been shown to considerably improve learning and memory in rodents. However, knowledge about the effects of EE on social interaction is generally limited and rather controversial. Thus, our aim was to evaluate both novel object recognition and agonistic behavior in NMRI mice receiving EE, hypothesizing enhanced cognition and slightly enhanced agonistic interaction upon EE rearing. During a 4-week period half the mice (n = 16) were exposed to EE and the other half (n = 16) remained in a standard environment (SE). On PND 56-57, animals performed the object recognition test, in which recognition memory was measured using a discrimination index. The social interaction test consisted of an encounter between an experimental animal and a standard opponent. Results indicated that EE mice explored the new object for longer periods than SE animals (P < .05). During social encounters, EE mice devoted more time to sociability and agonistic behavior (P < .05) than their non-EE counterparts. In conclusion, EE has been shown to improve object recognition and increase agonistic behavior in adolescent/early adulthood mice. In the future we intend to extend this study on a longitudinal basis in order to assess in more depth the effect of EE and the consistency of the above-mentioned observations in NMRI mice.

  10. Conversion of the interleukin 1 receptor antagonist into an agonist by site-specific mutagenesis.

    PubMed Central

    Ju, G; Labriola-Tompkins, E; Campen, C A; Benjamin, W R; Karas, J; Plocinski, J; Biondi, D; Kaffka, K L; Kilian, P L; Eisenberg, S P

    1991-01-01

    Interleukin 1 (IL-1) receptor antagonist (IL-1ra) is a naturally occurring protein that binds to the IL-1 receptor present on T cells, fibroblasts, and other cell types and acts to block IL-1-induced responses. IL-1ra is a pure antagonist and has no agonist activity in in vitro or in vivo systems. By site-specific mutagenesis, an analog of IL-1ra was created that contained a substitution of a single amino acid, Lys-145----Asp. This analog, IL-1ra K145D, exhibited partial agonist activity in the D10.G4.1 cell proliferation assay. The newly acquired agonist activity could not be neutralized by antisera to IL-1 alpha or IL-1 beta, but it could be blocked by a monoclonal antibody to the T-cell IL-1 receptor. The analog also showed agonist activity as assayed by increased prostaglandin E2 synthesis from CHO cells expressing recombinant mouse IL-1 receptor. These results with IL-1ra K145D demonstrate the importance of the region surrounding the corresponding Asp-145 residue in IL-1 beta for triggering the biological response to IL-1. Images PMID:1826365

  11. In silico analysis of the binding of agonists and blockers to the β2-adrenergic receptor

    PubMed Central

    Vilar, Santiago; Karpiak, Joel; Berk, Barkin; Costanzi, Stefano

    2011-01-01

    Activation of G protein-coupled receptors (GPCRs) is a complex phenomenon. Here, we applied Induced Fit docking (IFD) in tandem with linear discriminant analysis (LDA) to generate hypotheses on the conformational changes induced to the β2-adrenergic receptor by agonist binding, preliminary to the sequence of events that characterize activation of the receptor. This analysis, corroborated by a follow-up molecular dynamics study, suggested that agonists induce subtle movements to the fifth transmembrane domain (TM5) of the receptor. Furthermore, molecular dynamics also highlighted a correlation between movements of TM5 and the second extracellular loop (EL2), suggesting that freedom of motion of EL2 is required for the agonist-induced TM5 displacement. Importantly, we also showed that the IFD/LDA procedure can be used as a computational means to distinguish agonists from blockers on the basis of the differential conformational changes induced to the receptor. In particular, the two most predictive models obtained are based on the RMSD induced to Ser207 and on the counterclockwise rotation induced to TM5. PMID:21334234

  12. The use of Toll-like receptor 7/8 agonists as vaccine adjuvants.

    PubMed

    Vasilakos, John P; Tomai, Mark A

    2013-07-01

    Small molecule Toll-like receptor (TLR) 7/8 agonists have demonstrated potential as vaccine adjuvants, since they directly activate APCs and can enhance both humoral and cellular immune responses, especially Th1 responses. Although the natural ligands for TLR7 and TLR8 are ssRNA, the vast majority of vaccine studies performed thus far have been performed with synthetic small molecule imidazoquinolines, such as imiquimod and resiquimod. Despite the approved clinical use of the topical TLR7 agonist, imiquimod (Aldara(®) Imiquimod 5% cream; 3M, MN, USA), for external genital warts, superficial basal cell carcinoma and actinic keratosis, no vaccines using TLR7, TLR8 or TLR7/8 agonists have progressed beyond early-phase clinical studies thus far. This review will highlight the nonclinical and clinical studies that indicate promise for TLR7/8 ligands as vaccine adjuvants, reasons for inconsistent results thus far, problems with current technology and potential paths forward for TLR7/8 agonists as vaccine adjuvants.

  13. NICOTINE EFFECTS ON THE ACTIVITY OF MICE EXPOSED PRENATALLY TO THE NICOTINIC AGONIST ANATOXIN-A.

    EPA Science Inventory

    Considerable research has shown long-lasting effects of early exposure in experimental animals to nicotine. Anatoxin-a is produced by cyanobacteria and has been shown to be a potent nicotinic agonist. This experiment evaluated the motor activity of adult mice, and their respons...

  14. Characterizing novel metabolic pathways of melatonin receptor agonist agomelatine using metabolomic approaches

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agomelatine (AGM), an analog of melatonin, is a potential agonist at melatonin receptors 1/2 and a selective antagonist at 5-hydroxytryptamine 2C receptors. AGM is widely used for the treatment of major depressive episodes in adults. However, multiple adverse effects associated with AGM have been re...

  15. CoMSIA study on substituted aryl alkanoic acid analogs as GPR40 agonists.

    PubMed

    Bhatt, Aaditya; Patel, Pallav D; Patel, Maulik R; Singh, Satyakam; Lau-Cam, Cesar A; Talele, Tanaji T

    2011-05-01

    GPR40, a G-protein-coupled receptor has been well established to play a crucial role in regulating blood glucose levels. Hence, GPR40 is a potential target for future antidiabetic agents. The present 3D QSAR study is aimed at delineating structural parameters governing GPR40 agonistic activity. To meet this objective, a comparative molecular similarity indices analysis for 63 different GPR40 agonists was performed using two methods; a ligand-based 3D QSAR model employing the atom fit alignment method and a receptor-based 3D QSAR model that was derived from the predicted binding conformations obtained by docking all the GPR40 agonists at the active site of GPR40. The results of these studies showed the ligand-based model to be superior (r(cv)(2) value of 0.610) to the receptor-based model (r(cv)(2) value of 0.519) in terms of statistical data. The predictive ability of these models was evaluated using a test set of 15 compounds not included in the preliminary training set of 48 compounds. The predictive r(2) values for the ligand- and the receptor-based models were found to be 0.863 and 0.599, respectively. Further, interpretation of the comparative molecular similarity indices analysis contour maps with reference to the active site of GPR40 provided an insight into GPR40-agonist interactions. PMID:21352503

  16. Peroxisome proliferator-activated receptor-delta agonist ameliorated inflammasome activation in nonalcoholic fatty liver disease

    PubMed Central

    Lee, Hyun Jung; Yeon, Jong Eun; Ko, Eun Jung; Yoon, Eileen L; Suh, Sang Jun; Kang, Keunhee; Kim, Hae Rim; Kang, Seoung Hee; Yoo, Yang Jae; Je, Jihye; Lee, Beom Jae; Kim, Ji Hoon; Seo, Yeon Seok; Yim, Hyung Joon; Byun, Kwan Soo

    2015-01-01

    AIM: To evaluate the inflammasome activation and the effect of peroxisome proliferator-activated receptors (PPAR)-δ agonist treatment in nonalcoholic fatty liver disease (NAFLD) models. METHODS: Male C57BL/6J mice were classified according to control or high fat diet (HFD) with or without PPAR-δ agonist (GW) over period of 12 wk [control, HFD, HFD + lipopolysaccharide (LPS), HFD + LPS + GW group]. HepG2 cells were exposed to palmitic acid (PA) and/or LPS in the absence or presence of GW. RESULTS: HFD caused glucose intolerance and hepatic steatosis. In mice fed an HFD with LPS, caspase-1 and interleukin (IL)-1β in the liver were significantly increased. Treatment with GW ameliorated the steatosis and inhibited overexpression of pro-inflammatory cytokines. In HepG2 cells, PA and LPS treatment markedly increased mRNA of several nucleotide-binding and oligomerization domain-like receptor family members (NLRP3, NLRP6, and NLRP10), caspase-1 and IL-1β. PA and LPS also exaggerated reactive oxygen species production. All of the above effects of PA and LPS were reduced by GW. GW also enhanced the phosphorylation of AMPK-α. CONCLUSION: PPAR-δ agonist reduces fatty acid-induced inflammation and steatosis by suppressing inflammasome activation. Targeting the inflammasome by the PPAR-δ agonist may have therapeutic implication for NAFLD. PMID:26668503

  17. Novel Zn2+ Modulated GPR39 Receptor Agonists Do Not Drive Acute Insulin Secretion in Rodents

    PubMed Central

    Yasuda, Shin-ichiro; Tsuchida, Takuma; Oguma, Takahiro; Marley, Anna; Wennberg-Huldt, Charlotte; Hovdal, Daniel; Fukuda, Hajime; Yoneyama, Yukimi; Sasaki, Kazuyo; Johansson, Anders; Lundqvist, Sara; Brengdahl, Johan; Isaacs, Richard J.; Brown, Daniel; Geschwindner, Stefan; Benthem, Lambertus; Priest, Claire; Turnbull, Andrew

    2015-01-01

    Type 2 diabetes (T2D) occurs when there is insufficient insulin release to control blood glucose, due to insulin resistance and impaired β-cell function. The GPR39 receptor is expressed in metabolic tissues including pancreatic β-cells and has been proposed as a T2D target. Specifically, GPR39 agonists might improve β-cell function leading to more adequate and sustained insulin release and glucose control. The present study aimed to test the hypothesis that GPR39 agonism would improve glucose stimulated insulin secretion in vivo. A high throughput screen, followed by a medicinal chemistry program, identified three novel potent Zn2+ modulated GPR39 agonists. These agonists were evaluated in acute rodent glucose tolerance tests. The results showed a lack of glucose lowering and insulinotropic effects not only in lean mice, but also in diet-induced obese (DIO) mice and Zucker fatty rats. It is concluded that Zn2+ modulated GPR39 agonists do not acutely stimulate insulin release in rodents. PMID:26720709

  18. Agonistic aptamer to the insulin receptor leads to biased signaling and functional selectivity through allosteric modulation

    PubMed Central

    Yunn, Na-Oh; Koh, Ara; Han, Seungmin; Lim, Jong Hun; Park, Sehoon; Lee, Jiyoun; Kim, Eui; Jang, Sung Key; Berggren, Per-Olof; Ryu, Sung Ho

    2015-01-01

    Due to their high affinity and specificity, aptamers have been widely used as effective inhibitors in clinical applications. However, the ability to activate protein function through aptamer-protein interaction has not been well-elucidated. To investigate their potential as target-specific agonists, we used SELEX to generate aptamers to the insulin receptor (IR) and identified an agonistic aptamer named IR-A48 that specifically binds to IR, but not to IGF-1 receptor. Despite its capacity to stimulate IR autophosphorylation, similar to insulin, we found that IR-A48 not only binds to an allosteric site distinct from the insulin binding site, but also preferentially induces Y1150 phosphorylation in the IR kinase domain. Moreover, Y1150-biased phosphorylation induced by IR-A48 selectively activates specific signaling pathways downstream of IR. In contrast to insulin-mediated activation of IR, IR-A48 binding has little effect on the MAPK pathway and proliferation of cancer cells. Instead, AKT S473 phosphorylation is highly stimulated by IR-A48, resulting in increased glucose uptake both in vitro and in vivo. Here, we present IR-A48 as a biased agonist able to selectively induce the metabolic activity of IR through allosteric binding. Furthermore, our study also suggests that aptamers can be a promising tool for developing artificial biased agonists to targeted receptors. PMID:26245346

  19. Systemic cancer immunotherapy with Toll-like receptor 7 agonists: Timing is everything.

    PubMed

    Hotz, Christian; Bourquin, Carole

    2012-03-01

    Toll-like receptor (TLR) 7 agonists represent a promising strategy for the immunotherapy of cancer. We have recently investigated the influence of TLR tolerance on the efficacy of systemic tumor treatment with TLR7 ligands. We propose that considering the kinetics of receptor sensitivity highly improves the outcome of cancer immunotherapy. PMID:22720251

  20. Differential Effects of Cannabinoid Receptor Agonist on Social Discrimination and Contextual Fear in Amygdala and Hippocampus

    ERIC Educational Resources Information Center

    Segev, Amir; Akirav, Irit

    2011-01-01

    We examined whether the cannabinoid receptor agonist WIN55,212-2 (WIN; 5 [mu]g/side) microinjected into the hippocampus or the amygdala would differentially affect memory processes in a neutral vs. an aversive task. In the aversive contextual fear task, WIN into the basolateral amygdala impaired fear acquisition/consolidation, but not retrieval.…