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Sample records for 5-ht3 antagonist tropisetron

  1. The effects of the 5-HT3 receptor antagonist tropisetron on cocaine-induced conditioned taste aversions.

    PubMed

    Briscione, Maria A; Serafine, Katherine M; Merluzzi, Andrew P; Rice, Kenner C; Riley, Anthony L

    2013-04-01

    Although cocaine readily induces taste aversions, little is known about the mechanisms underlying this effect. Recent work has shown that cocaine's actions on serotonin (5-HT) may be involved. To address this possibility, the present experiments examined a role of the specific 5-HT receptor, 5-HT3, in this effect given that it is implicated in a variety of behavioral effects of cocaine. This series of investigations first assessed the aversive effects of the 5-HT3 receptor antagonist tropisetron alone (Experiment 1). Specifically, in Experiment 1 male Sprague-Dawley rats were given repeated pairings of a novel saccharin solution and tropisetron (0, 0.056, 0.18 and 0.56mg/kg). Following this, a non-aversion-inducing dose of tropisetron (0.18mg/kg) was assessed for its ability to block aversions induced by a range of doses of cocaine (Experiment 2). Specifically, in Experiment 2 animals were given access to a novel saccharin solution and then injected with tropisetron (0 or 0.18mg/kg) followed by an injection of various doses of cocaine (0, 10, 18 and 32mg/kg). Cocaine induced dose-dependent taste aversions that were not blocked by tropisetron, suggesting that cocaine's aversive effects are not mediated by 5-HT, at least at this specific receptor subtype. At the intermediate dose of cocaine, aversions appeared to be potentiated, suggesting 5-HT3 may play a limiting role in cocaine's aversive effects. These data are discussed in the context of previous examinations of the roles of serotonin, dopamine, and norepinephrine in cocaine-induced aversions.

  2. Acute treatment with 5-HT3 receptor antagonist, tropisetron, reduces immobility in intact female rats exposed to the forced swim test.

    PubMed

    Bravo, Gabriela; Maswood, Sharmin

    2006-10-01

    The effects of tropisetron, a 5-HT3 receptor antagonist, were evaluated in adult Fischer female rats exposed to the Forced Swim Test (FST). Rats selected on the days of proestrus or estrus was immersed in a cylinder of water for 2 consecutive days. Rats were exposed to the FST for 15 min on day 1 (pretest), followed by a 5-min session (test), 24 h later. The proestrous-estrous group consisted of rats that were exposed to the FST on their proestrous stage (pretest); then 24 h later the same rats were exposed to the FST on their estrous stage (test). Rats in the estrous-diestrous group were exposed to the FST on their estrous stage (pretest) and 24 h later on their diestrous stage (test). Rats were injected intraperitoneally with saline or 1.0 or 2.0 mg/kg tropisetron 30 min prior to exposure to the cylinder on the test day. Immobility, swimming, and struggling behaviors were scored for 5 min. There was a significant decline in immobility after treatment with 2.0 mg/kg tropisetron in both groups. In addition, a significant decline in swimming was observed in the estrous rats (proestrous-estrous group) after treatment with 2.0 mg/kg tropisetron. There were no significant effects of tropisetron on struggling in any groups examined.

  3. [5-HT3 receptor antagonist als analgetics in rheumatic diseases].

    PubMed

    Müller, W; Fiebich, B L; Stratz, T

    2006-10-01

    Various rheumatic diseases like fibromyalgia, systemic inflammatory rheumatic disorders and localized diseases, such as arthritides and activated arthroses, tendinopathies and periarthropathies, as well as trigger points can be improved considerably by treatment with the 5-HT3 receptor antagonist tropisetron. Particularly in the latter group of diseases, local injections have done surprisingly rapid analgesic action. This effect matches that of local anesthetics, but lasts considerably longer and is comparable to local injections of local anesthetics combined with corticosteroids. The action of the 5-HT3 receptor antagonists can be attributed to an antinociceptive effect that occurs at the same time as an antiphlogistic and probably also an immunosuppressive effect. Whereas an inhibited release of substance P from the nociceptors, and possibly some other neurokins as well, seems to be the most likely explanation for the antinociceptive action, the antiphlogistic effect is primarily due to an inhibited formation of various different phlogistic substances; in some conditions, like systemic inflammatory rheumatic diseases, for example, the 5-HT3 receptor antagonists may exert an immunosuppressive effect in addition to this.

  4. From Chemotherapy-Induced Emesis to Neuroprotection: Therapeutic Opportunities for 5-HT3 Receptor Antagonists.

    PubMed

    Fakhfouri, Gohar; Mousavizadeh, Kazem; Mehr, Sharam Ejtemaei; Dehpour, Ahmad Reza; Zirak, Mohammad Reza; Ghia, Jean-Eric; Rahimian, Reza

    2015-12-01

    5-HT3 receptor antagonists are extensively used as efficacious agents in counteracting chemotherapy-induced emesis. Recent investigations have shed light on other potential effects (analgesic, anxiolytic, and anti-psychotic). Some studies have reported neuroprotective properties for the 5-HT3 receptor antagonists in vitro and in vivo. When administered to Aβ-challenged rat cortical neurons, 5-HT3 receptor antagonists substantially abated apoptosis, elevation of cytosolic Ca(2), glutamate release, reactive oxygen species (ROS) generation, and caspase-3 activity. In addition, in vivo studies show that 5-HT3 receptor antagonists possess, alongside their anti-emetic effects, notable immunomodulatory properties in CNS. We found that pretreatment with tropisetron significantly improved neurological deficits and diminished leukocyte transmigration into the brain, TNF-α level, and brain infarction in a murine model of embolic stroke. Our recent investigation revealed that tropisetron protects against Aβ-induced neurotoxicity in vivo through both 5-HT3 receptor-dependent and -independent pathways. Tropisetron, in vitro, was found to be an efficacious inhibitor of the signaling pathway leading to the activation of pro-inflammatory NF-κB, a transcription factor pivotal to the upregulation of several neuroinflammatory mediators in brain. This mini review summarizes novel evidence concerning effects of 5-HT3 antagonists and their possible mechanisms of action in ameliorating neurodegenerative diseases including Alzheimer, multiple sclerosis, and stroke. Further, we discuss some newly synthesized 5-HT3 receptor antagonists with dual properties of 5-HT3 receptor blockade/alpha-7 nicotinic receptor activator and their potential in management of memory impairment. Since 5-HT3 receptor antagonists possess a large therapeutic window, they can constitute a scaffold for design and synthesis of new neuroprotective medications.

  5. Spinal 5-HT3 receptor mediates nociceptive effect on central neuropathic pain; possible therapeutic role for tropisetron

    PubMed Central

    Nasirinezhad, Farinaz; Hosseini, Marjan; Karami, Zohre; Yousefifard, Mahmoud; Janzadeh, Autosa

    2016-01-01

    Objectives To test the analgesic effect of 5-HT-3 receptor antagonist, tropisetron, in a clip compression injury model of spinal cord pain in rats. Methods Four weeks post compression of the spinal cord at lumbar level, tropisetron was administered intrathecally at 100 μg and 150 μg dosages. Behavioral tests were assessed before administration. Fifteen minutes after injection, behavioral tests were repeated. Randall-Sellitto and plantar test was used for mechanical and thermal hyperalgesia, respectively. Mechanical and cold allodynia were evaluated by Von Frey filament and acetone droplets, respectively. The analgesic effect of tropisetron was compared with intrathecal administration of salicylate. Locomotor score was evaluated by Basso, Beattie and Bresnahan (BBB) test every week after spinal cord injury. Results Intrathecal administration of tropisetron, decreased hyperalgesia and mechanical allodynia, but not cold allodynia were observed after compression of the spinal cord. Conclusion Blockade of 5-HT-3 receptors by tropisetron at the spinal level induces an antinociceptive effect on chronic central neuropathic pain and suggests that this compound may have potential clinical utility for the management of central neuropathic pain, particularly in patients with hyperalgesia and tactile allodynia. PMID:26338446

  6. Downregulated hypothalamic 5-HT3 receptor expression and enhanced 5-HT3 receptor antagonist-mediated improvement in fatigue-like behaviour in cholestatic rats.

    PubMed

    Nguyen, H; Wang, H; le, T; Ho, W; Sharkey, K A; Swain, M G

    2008-03-01

    The serotonin neurotransmitter system, including the 5-HT(3) receptor, has been implicated in the genesis of fatigue in patients with liver disease. Therefore, we examined the possible role of 5-HT(3) receptors in cholestasis-associated fatigue. Rats were either bile duct resected (BDR) or sham resected and studied 10 days postsurgery. A significant decrease in hypothalamic 5-HT(3) receptor expression was detected by immunohistochemistry and Western blot in BDR vs sham rats, coupled with increased hypothalamic serotonin turnover identified by an elevated 5-hydroxyindoleacetic acid (5-HIAA) to 5-HT ratio in BDR vs sham rats. To examine fatigue-like behaviour, an activity meter was used. BDR rats exhibited significantly lower locomotor activity than did sham animals. Subcutaneous injection of the 5-HT(3) receptor antagonist tropisetron (0.1 mg kg(-1)) resulted in significantly increased locomotor activity in BDR rats compared to the activity in saline-treated controls, but was without effect in sham rats. However, a 10-fold higher dose of tropisetron significantly increased locomotor activity in both BDR and sham rats compared to saline-injected controls. These findings indicate that cholestasis in the rat is associated with increased hypothalamic serotonin turnover, decreased hypothalamic 5-HT(3) receptor expression, and enhanced sensitivity to locomotor activation induced by 5-HT(3) receptor antagonism, thereby implicating the 5-HT(3) receptor system in cholestasis associated fatigue.

  7. [Medical economics evaluation of 5-HT3 receptor antagonist drugs].

    PubMed

    Utsunomiya, Junpei; Hirano, Shigeki; Fukui, Aiko; Funabashi, Kazuaki; Deguchi, Yuko; Yamada, Susumu; Naito, Kazuyuki

    2010-10-01

    At Komaki City Hospital, the drug cost in connection with cancer chemotherapy was re-examined as part of improved management along with the introduction of DPC in July 2008. With due attention to the 5-HT3 receptor antagonists, both the change from injections to oral drugs and the change from brand-name drugs to generic drugs were tried between July 2008 and June 2009. After that, in order to examine the economic impact of these changes, we investigated and analyzed the number of medications, the cost of medicine purchased, and the average drug cost per medication of the 5-HT3 receptor antagonists between April 2008 and September 2009. As a result, the cost of 5-HT3 receptor antagonists purchased decreased greatly, and the impact of the improvement was mainly due to the change to oral drugs, and partially to the change to generic drugs. Therefore, from the viewpoint of hospital economic improvement in DPC, it was thought that the change to oral drugs(5-HT3 receptor antagonists)is given top priority.

  8. 5-HT3 receptors antagonists reduce serotonin-induced scratching in mice.

    PubMed

    Ostadhadi, Sattar; Kordjazy, Nastaran; Haj-Mirzaian, Arya; Mansouri, Parvin; Dehpour, Ahmad Reza

    2015-06-01

    Serotonin (5-hydroxytryptamine, 5-HT) acts as a pruritogen in humans and animals, but the mechanisms of action through that serotonin induces itch response have not been extensively discovered. In our study, we attempted to investigate the role of 5-HT3 receptors in scratching behavior due to intradermal serotonin injection. Intradermal injection of serotonin (14.1-235 nmol/site) into the nape of the neck of mice was performed to elicit itch. Scratching behavior was evaluated by measuring the number of bouts during 60 min after injection. We evaluated the effect of intraperitoneal pretreatment with ondansetron and tropisetron (0.1, 0.3, and 1 mg/kg) on itch induced by serotonin. Also, intradermal ondansetron and tropisetron at doses 50, 100, and 200 nmol/site were concurrently administrated with serotonin. Serotonin produced a significant enhancement in scratching at dose 141 nmol/site. Concurrent administration of ondansetron (50, 100, and 200 nmol/site) and tropisetron (100 and 200 nmol/site) with serotonin reduced scratching activity compared to the animals that only received serotonin. Also, pretreatment with intraperitoneal ondansetron and tropisetron (0.3 and 1 mg/kg) 30 min before serotonin attenuated the itch response. We showed that the scratching induced by intradermal serotonin is mediated by 5-HT3 receptors subtype. It can be concluded that 5-HT3 may play a role in mediating serotonin-associated itch responses, and we introduce 5-HT3 receptors as possible targets for antipruritic agents.

  9. Local-anesthetic like inhibition of the cardiac sodium channel Nav1.5 α-subunit by 5-HT3 receptor antagonists.

    PubMed

    Van't Klooster, Mariet P; Foadi, Nilufar; Hage, Axel; Stoetzer, Carsten; Wegner, Florian; Eberhardt, Mirjam; Leffler, Andreas

    2016-10-15

    5-hydroxytryptamine 3 receptor (5-HT3 receptor) antagonists are administered for prevention and therapy of nausea and vomiting. Although regarded as safe therapeutics, they can also provoke arrhythmias by prolonging the QRS interval. However, the mechanisms mediating this cardiotoxicity are poorly understood. Here we investigated effects of 5-HT3 receptor antagonists on the cardiac Na(+) channel Nav1.5. We explored the interaction of dolasetron, tropisetron, granisetron and ondansetron on the human α-subunit Nav1.5 heterologously expressed in HEK293 cells. Sodium currents were explored by means of whole-cell patch clamp recordings. All four substances inhibited the Nav1.5 in a concentration and state-dependent manner. Dolasetron displayed the lowest blocking efficacy, and tropisetron was the most potent blocker with a half maximum blocking concentration of 18µM for tonic block of inactivated channels. Tropisetron was also the most potent use-dependent inhibitor, and it also induced a strong open -channel block. Both tonic and use-dependent block by tropisetron were abbreviated on the local-anesthetic insensitive mutant Nav1.5-F1760A. Co-administration of tropisetron and the local anesthetic bupivacaine or the hypnotic propofol augmented inhibition of Nav1.5. Our data demonstrate that 5-HT3 receptor antagonists induce a local-anesthetic like inhibition of Nav1.5, and that they display different blocking efficacies. Reports on a relevant cardiotoxicity of dolasetron as opposed to other 5-HT3 receptor antagonists do not seem to correlate with a block of Nav1.5. As inhibition of Nav1.5 was enhanced by propofol and bupivacaine however, it is possible that a combined administration of Na(+) channel blockers and 5-HT3 receptor antagonists can provoke arrhythmias.

  10. Synergistic antiemetic interactions between serotonergic 5-HT3 and tachykininergic NK1-receptor antagonists in the least shrew (Cryptotis parva).

    PubMed

    Darmani, Nissar A; Chebolu, Seetha; Amos, Barry; Alkam, Tursun

    2011-10-01

    Significant electrophysiological and biochemical findings suggest that receptor cross-talk occurs between serotonergic 5-HT(3)- and tachykininergic NK(1)-receptors in which co-activation of either receptor by ineffective doses of their corresponding agonists (serotonin (5-HT) or substance P (SP), respectively) potentiates the activity of the other receptor to produce a response. In contrast, selective blockade of any one of these receptors attenuates the increase in abdominal vagal afferent activity caused by either 5-HT or SP. This interaction has important implications in chemotherapy-induced nausea and vomiting (CINV) since 5-HT(3)- and NK(1)-receptor antagonists are the major classes of antiemetics used in cancer patients receiving chemotherapy. The purpose of this study was to demonstrate whether the discussed interaction produces effects at the behavioral level in a vomit-competent species, the least shrew. Our results demonstrate that pretreatment with either a 5-HT(3) (tropisetron)- or an NK(1) (CP99,994)-receptor specific antagonist, attenuates vomiting caused by a selective agonist (2-methyl 5-HT or GR73632, respectively) of both emetic receptors. In addition, relative to each antagonist alone, their combined doses were 4-20 times more potent against vomiting caused by each emetogen. Moreover, combined sub-maximal doses of the agonists 2-methyl 5-HT and GR73632, produced 8-12 times greater number of vomits relative to each emetogen tested alone. However, due to large variability in vomiting caused by the combination doses, the differences failed to attain significance. The antiemetic dose-response curves of tropisetron against both emetogens were U-shaped probably because larger doses of this antagonist behave as a partial agonist. The data demonstrate that 5-HT(3)- and NK(1)-receptors cross-talk to produce vomiting, and that synergistic antiemetic effects occur when both corresponding antagonists are concurrently used against emesis caused by each

  11. Is All Radiation-Induced Emesis Ameliorated by 5-HT3 Receptor Antagonists

    DTIC Science & Technology

    1992-01-01

    5 - HT3 receptor antagonists ;~// 9-72 Bernard M.I Rabin 0’) and Gregory L. Kingt2) -) Behavioral Sciences and 2 PhYSzo~o~y Dcpiarlrnvni . Arm,. ii - R...RY Exposing ferrets to gamuma rays or X-rays produces vomiting that can be attenuated by 5 - HT3 receptor antagonists and by subdiaphraqmatic vagotomy...Pretreating ferrets with serotonin type-3 ( 5 - HT3 ) receptor antagonists or performing bilateral subdiaphragmatic vagotomy reliably attenuates the

  12. Stability of tramadol with three 5-HT3 receptor antagonists in polyolefin bags for patient-controlled delivery systems

    PubMed Central

    Chen, Fu-chao; Zhu, Jun; Li, Bin; Yuan, Fang-jun; Wang, Lin-hai

    2016-01-01

    Background Mixing 5-hydroxytryptamine-3 (5-HT3) receptor antagonists with patient-controlled analgesia (PCA) solutions of tramadol has been shown to decrease the incidence of nausea and vomiting associated with the use of tramadol PCA for postoperative pain. However, such mixtures are not commercially available, and the stability of the drug combinations has not been duly studied. The study aimed to evaluate the stability of tramadol with three 5-HT3 receptor antagonists in 0.9% sodium chloride injection for PCA administration. Materials and methods Test samples were prepared by adding 1,000 mg tramadol hydrochloride, 8 mg ondansetron hydrochloride, and 6 mg granisetron hydrochloride or 5 mg tropisetron hydrochloride to 100 mL of 0.9% sodium chloride injection in polyolefin bags. The samples were prepared in triplicates, stored at either 25°C or 4°C for 14 days, and assessed using the following compatibility parameters: precipitation, cloudiness, discoloration, and pH. Chemical stability was also determined using a validated high-pressure liquid chromatography method. Results All of the mixtures were clear and colorless throughout the initial observation period. No change in the concentration of tramadol hydrochloride occurred with any of the 5-HT3 receptor antagonists during the 14 days. Similarly, little or no loss of the 5-HT3 receptor antagonists occurred over the 14-day period. Conclusion Our results suggest that mixtures of tramadol hydrochloride, ondansetron hydrochloride, granisetron hydrochloride, or tropisetron hydrochloride in 0.9% sodium chloride injection were physically and chemically stable for 14 days when stored in polyolefin bags at both 4°C and 25°C. PMID:27350741

  13. Stability of tramadol with three 5-HT3 receptor antagonists in polyolefin bags for patient-controlled delivery systems.

    PubMed

    Chen, Fu-Chao; Zhu, Jun; Li, Bin; Yuan, Fang-Jun; Wang, Lin-Hai

    2016-01-01

    Mixing 5-hydroxytryptamine-3 (5-HT3) receptor antagonists with patient-controlled analgesia (PCA) solutions of tramadol has been shown to decrease the incidence of nausea and vomiting associated with the use of tramadol PCA for postoperative pain. However, such mixtures are not commercially available, and the stability of the drug combinations has not been duly studied. The study aimed to evaluate the stability of tramadol with three 5-HT3 receptor antagonists in 0.9% sodium chloride injection for PCA administration. Test samples were prepared by adding 1,000 mg tramadol hydrochloride, 8 mg ondansetron hydrochloride, and 6 mg granisetron hydrochloride or 5 mg tropisetron hydrochloride to 100 mL of 0.9% sodium chloride injection in polyolefin bags. The samples were prepared in triplicates, stored at either 25°C or 4°C for 14 days, and assessed using the following compatibility parameters: precipitation, cloudiness, discoloration, and pH. Chemical stability was also determined using a validated high-pressure liquid chromatography method. All of the mixtures were clear and colorless throughout the initial observation period. No change in the concentration of tramadol hydrochloride occurred with any of the 5-HT3 receptor antagonists during the 14 days. Similarly, little or no loss of the 5-HT3 receptor antagonists occurred over the 14-day period. Our results suggest that mixtures of tramadol hydrochloride, ondansetron hydrochloride, granisetron hydrochloride, or tropisetron hydrochloride in 0.9% sodium chloride injection were physically and chemically stable for 14 days when stored in polyolefin bags at both 4°C and 25°C.

  14. Effects of iodoproxyfan, a potent and selective histamine H3 receptor antagonist, on alpha 2 and 5-HT3 receptors.

    PubMed

    Schlicker, E; Pertz, H; Bitschnau, H; Purand, K; Kathmann, M; Elz, S; Schunack, W

    1995-07-01

    We determined the affinity and/or potency of the novel H3 receptor antagonist iodoproxyfan at alpha 2 and 5-HT3 receptors. Iodoproxyfan and rauwolscine (a reference alpha 2 ligand) (i) monophasically displaced 3H-rauwolscine binding to rat brain cortex membranes (pKi 6.79 and 8.59); (ii) facilitated the electrically evoked tritium overflow from superfused mouse brain cortex slices preincubated with 3H-noradrenaline (pEC50 6.46 and 7.91) and (iii) produced rightward shifts of the concentration-response curve (CRC) of (unlabelled) noradrenaline for its inhibitory effect on the evoked overflow (pA2 6.65 and 7.88). In the guinea-pig ileum, iodoproxyfan 6.3 mumol/l failed to evoke a contraction by itself but depressed the maximum of the CRC of 5-hydroxytryptamine (pD'2 5.24). Tropisetron (a reference 5-HT3 antagonist) produced rightward shifts of the CRC of 5-hydroxytryptamine (pA2 7.84). In conclusion, the affinity/potency of iodoproxyfan at H3 receptors (range 8.3-9.7 [1]) exceeds that at alpha 2 receptors by at least 1.5 log units and that at 5-HT3 receptors by at least 3 log units.

  15. The muscarinic antagonists scopolamine and atropine are competitive antagonists at 5-HT3 receptors.

    PubMed

    Lochner, Martin; Thompson, Andrew J

    2016-09-01

    Scopolamine is a high affinity muscarinic antagonist that is used for the prevention of post-operative nausea and vomiting. 5-HT3 receptor antagonists are used for the same purpose and are structurally related to scopolamine. To examine whether 5-HT3 receptors are affected by scopolamine we examined the effects of this drug on the electrophysiological and ligand binding properties of 5-HT3A receptors expressed in Xenopus oocytes and HEK293 cells, respectively. 5-HT3 receptor-responses were reversibly inhibited by scopolamine with an IC50 of 2.09 μM. Competitive antagonism was shown by Schild plot (pA2 = 5.02) and by competition with the 5-HT3 receptor antagonists [(3)H]granisetron (Ki = 6.76 μM) and G-FL (Ki = 4.90 μM). The related molecule, atropine, similarly inhibited 5-HT evoked responses in oocytes with an IC50 of 1.74 μM, and competed with G-FL with a Ki of 7.94 μM. The reverse experiment revealed that granisetron also competitively bound to muscarinic receptors (Ki = 6.5 μM). In behavioural studies scopolamine is used to block muscarinic receptors and induce a cognitive deficit, and centrally administered concentrations can exceed the IC50 values found here. It is therefore possible that 5-HT3 receptors are also inhibited. Studies that utilise higher concentrations of scopolamine should be mindful of these potential off-target effects.

  16. Method for individualized evaluation of antiemetic effect induced by 5-HT3 receptor antagonist.

    PubMed

    Nakamura, Hironori; Yokoyama, Haruko; Yoshimoto, Koichi; Nakajima, Akihiro; Okuyama, Kiyoshi; Iwase, Osamu; Yamada, Yasuhiko

    2013-01-01

    5-HT3 receptor antagonists are widely used for prevention of chemotherapy-induced nausea and vomiting, though their antiemetic effects vary among patients. We investigated a method for evaluation of antiemetic effects in individual patients. We used the 5-HT3 receptor occupancy of serotonin for our evaluation, which was estimated based on the plasma concentration of granisetron and concentration of serotonin near the 5-HT3 receptor in the small intestine, obtained by measuring the urinary concentrations of granisetron and 5-hydroxyindoleacetic acid (5-HIAA)/creatinine (Cre). The mean cumulative percent for urinary excretion of granisetron at 24 h after administration and coefficient of variation were 16.19 ± 6.30% and 38.91%, respectively. The time course of urinary concentration of 5-HIAA/Cre also varied among the patients. The value for 5-HT3 receptor occupancy of serotonin without granisetron was higher than that prior to administration (blank), thus most treated patients had the possibility of induced emesis. In contrast, that with granisetron was lower than the blank value, indicating that those treated patients would not develop emesis. Furthermore, the estimated 5-HT3 receptor occupancy of serotonin in the small intestine and actual individual patient condition corresponded well, showing the validity of our method. Our results suggest that it is possible to evaluate individual antiemetic effects by estimating the 5-HT3 receptor occupancy of serotonin in the small intestine based on plasma concentrations of granisetron and serotonin near the 5-HT3 receptor in the small intestine using noninvasive urine samples. This method of individual evaluation is considered to be useful and effective.

  17. The antimalarial drug proguanil is an antagonist at 5-HT3 receptors.

    PubMed

    Lochner, Martin; Thompson, Andrew J

    2014-12-01

    Proguanil is an antimalarial prodrug that is metabolized to 4-chlorophenyl-1-biguanide (CPB) and the active metabolite cycloguanil (CG). These compounds are structurally related to meta-chlorophenyl biguanide (mCPBG), a 5-hydroxytryptamine 3 (5-HT3) receptor agonist. Here we examine the effects of proguanil and its metabolites on the electrophysiology and ligand-binding properties of human 5-HT3A receptors expressed in Xenopus oocytes and human embryonic kidney 293 cells, respectively. 5-HT3 receptor responses were reversibly inhibited by proguanil, with an IC50 of 1.81 μM. Competitive antagonism was shown by a lack of voltage-dependence, Schild plot (Kb = 1.70 μM), and radioligand competition (Ki = 2.61 μM) with the 5-HT3 receptor antagonist [(3)H]granisetron. Kinetic measurements (kon = 4.0 × 10(4) M(-1) s(-1) ; koff = 0.23 s(-1)) were consistent with a simple bimolecular reaction scheme with a Kb of 4.35 μM. The metabolites CG and CPB similarly inhibited 5-HT3 receptors as assessed by IC50 (1.48 and 4.36 μM, respectively), Schild plot (Kb = 2.97 and 11.4 μM), and radioligand competition (Ki = 4.89 and 0.41 μM). At higher concentrations, CPB was a partial agonist (EC50 = 14.1 μM; I/Imax = 0.013). These results demonstrate that proguanil competitively inhibits 5-HT3 receptors, with an IC50 that exceeds whole-blood concentrations following its oral administration. They may therefore be responsible for the occasional gastrointestinal side effects, nausea, and vomiting reported following its use. Clinical development of related compounds should therefore consider effects at 5-HT3 receptors as an early indication of possible unwanted gastrointestinal side effects.

  18. Serotonin (5-HT3) receptor antagonists for the reduction of symptoms of low anterior resection syndrome

    PubMed Central

    Itagaki, Ryohei; Koda, Keiji; Yamazaki, Masato; Shuto, Kiyohiko; Kosugi, Chihiro; Hirano, Atsushi; Arimitsu, Hidehito; Shiragami, Risa; Yoshimura, Yukino; Suzuki, Masato

    2014-01-01

    Purpose Serotonin (5-hydroxytryptamine [5-HT])3 receptor antagonists are effective for the treatment of diarrhea-predominant irritable bowel syndrome (IBS-D), in which exaggerated intestinal/colonic hypermotility is often observed. Recent studies have suggested that the motility disorder, especially spastic hypermotility, seen in the neorectum following sphincter-preserving operations for rectal cancer may be the basis of the postoperative defecatory malfunction seen in these patients. We investigated the efficacy of 5-HT3 receptor antagonists in patients suffering from severe low anterior resection syndrome. Patients and methods A total of 25 male patients with complaints of uncontrollable urgency or fecal incontinence following sphincter-preserving operations were enrolled in this study. Defecatory status, assessed on the basis of incontinence score (0–20), urgency grade (0–3), and number of toilet visits per day, was evaluated using a questionnaire before and 1 month after the administration of the 5-HT3 antagonist ramosetron. Results All the parameters assessed improved significantly after taking ramosetron for 1 month. The effect was more prominent in cases whose anastomotic line was lower, ie, inside the anal canal. Defecatory function was better in patients who commenced ramosetron therapy within 6 months postoperatively, as compared to those who were not prescribed ramosetron for more than 7 months postoperatively. Conclusion These results suggest that 5-HT3 antagonists are effective for the treatment of low anterior resection syndrome, as in diarrhea-predominant irritable bowel syndrome. The improvement in symptoms is not merely time dependent, but it is related to treatment with 5-HT3 antagonists. PMID:24648748

  19. New benzimidazole derivatives: selective and orally active 5-HT3 receptor antagonists.

    PubMed

    Pascual, David; Girón, Rocío; Alsasua, Angela; Benhamú, Belinda; López-Rodríguez, María Luz; Martín, María Isabel

    2003-02-21

    The synthesis of new 5-HT(3) receptor antagonists is an interesting field of research because of their wide therapeutic use. The aim of this work is to functionally characterise a new series of benzimidazole derivatives previously described. These compounds bind to 5-HT(3) receptors and have been evaluated using in vitro (rat tunica muscularis mucosae) and in vivo tests (Bezold-Jarisch reflex in rat and gastrointestinal motility and spontaneous motility in mice). Ondansetron and 1-[4-amino-5-chloro-2-(3,5-dimethoxyphenil)methyloxy]-3-[1-[2-methylsulfonylamino]piperidin-4-yl]propan-1-one hydrochloride (RS 39604) were used as well known 5-HT(3) and 5-HT(4) receptor antagonists. These benzimidazole derivatives have proved to be 5-HT(3) receptor antagonists. Interestingly, they are as active as ondansetron when they are intraperitoneally (i.p.) or orally (p.o.) administered and, in mice, they seem to induce fewer behavioural changes at similar effective doses than does ondansetron. The present results confirm the usefulness of the previously proposed pharmacophore and justify the interest in these new benzimidazole derivatives.

  20. Changes in characteristics of the specific binding of [3H]LY-278584, a 5-HT3-receptor antagonist, on differentiated NG108-15 cells.

    PubMed

    Matsushima, Kayoko; Imanishi, Takashi; Asano, Hajime; Funakami, Yoshinori; Wada, Tetsuyuki; Ichida, Seiji

    2010-01-01

    We have reported previously that the concentration of intracellular Ca2+ evoked by serotonin (5-HT) was significantly augmented in differentiated NG108-15 (NG) cells treated with dibutyryl cAMP and the enhanced response occurred via 5-HT3 receptors. We investigated changes in the characteristics for specific binding of [(3)H]LY-278584 (a specific antagonist of the 5-HT3 receptor) on membranes from differentiated NG cells. The results indicated that the K(d) and B(max) values for the specific binding to differentiated NG cells were significantly smaller and larger, respectively, than those for undifferentiated NG cells. The binding was significantly inhibited by 10 nM tropisetron, a specific 5-HT3-receptor antagonist, but not by any other types of 5-HT-receptor antagonists. These results suggested that the enhanced response by 5-HT in differentiated NG cells was due to both qualitative and quantitative changes in the 5-HT3 receptor.

  1. Ondansetron, a selective 5-HT3 antagonist, antagonizes methamphetamine-induced anorexia in mice.

    PubMed

    Ginawi, O T; Al-Majed, A A; Al-Suwailem, A K

    2005-03-01

    Effects of some selective serotonergic (5-HT) antagonists on methamphetamine-induced anorexia were investigated in male mice. The least possible dose of methamphetamine alone that caused significant anorectic activity was 11 micromolkg(-1), i.p. (2 mgkg(-1)). Various doses of some selective serotonergic receptor antagonists were administered half an hour before the above mentioned dose of methamphetamine. Methiothepin potentiated, whereas NAN-190, methysergide, mianserin and ondansetron antagonized methamphetamine-induced anorectic activity. The least possible doses of these antagonists which modified methamphetamine-induced anorexia were as follows: methiothepin (1.1 micromolkg(-1), i.p.), NAN-190 (4.2 micromolkg(-1), i.p.), methysergide (2.1 micromolkg(-1), i.p.), mianserin (3.3 micromolkg(-1), i.p.) and ondansetron (0.003 micromolkg(-1), i.p.). The serotonergic antagonists at the above mentioned doses did not modify the food intake of animals not treated with methamphetamine, except for methiothepin, which produced a significant reduction, and mianserin, which produced a significant increase in food intake. The results of the present study indicated that the anorectic activity induced by methamphetamine is related to the interactions of methamphetamine with 5-HT receptor. Since a very small dose (0.003 micromolkg(-1)) of ondansetron (the 5-HT(3) antagonist), as compared with the other antagonists used in this study, antagonized the anorexia induced by methamphetamine, the 5-HT(3) receptor is likely to be the site for this interaction.

  2. [Cost-effectiveness analysis of 5-HT3 receptor antagonist drugs in cancer chemotherapy].

    PubMed

    Ishimaru, Hiromasa; Takayama, Shinji; Shiokawa, Mitsuru; Inoue, Tadao

    2008-04-01

    Recently, ambulatory treatment centers (ATC) are markedly increasingboth in number and scale. It is therefore important to consolidate an efficient therapeutic system. A decrease in both treatment time and waitingtime leads to not only the improvement of the quality of life (QOL) for patients but also the efficient use of personnel and running costs for medical institutions by reducingthe bed occupation rate. In ATC, 5-HT3 receptor antagonists are extensively used for high emetic risk patients. However, their high cost and prolonged treatment causes one of the problems in improvingthe efficiency of the therapeutic system when they are administered by intravenous infusion. Amongthe 4 types of 5-HT3 receptor antagonists (injections) currently available in Japan, azasetron is the only drugthat is not designated as a powerful drug and that can be administered by bolus intravenous infusion. In this study, we investigated azasetron and granisetron from the standpoint of pharmacoeconomics with a simulation model using the results of clinical studies in Japan. Accordingto the results of cost-effectiveness analysis, therapeutic and time costs per patient for azasetron 10 mgand granisetron 2 mg (calculated in consideration of both medical institutions and patients) was 8,219 and 10,193 yen, respectively. This gap was attributable to the time loss due to the difference in administration methods. The result suggests that this time loss is more significant not only for patients but also for medical staff than the loss attributable to the drugcost. Furthermore, the bolus intravenous infusion of azasetron is considered superior to the non-bolus intravenous infusion of granisetron from a pharmacoeconomic standpoint. It is desirable to choose the appropriate administration method of 5-HT3 receptor antagonists in various chemotherapy regimens for the purpose of reducingthe treatment time and promotingthe efficiency of the therapeutic system at ATCs.

  3. Theoretical evaluation of antiemetic effects of 5-HT3 receptor antagonists for prevention of vomiting induced by cisplatin.

    PubMed

    Nakamura, Hironori; Yokoyama, Haruko; Takayanagi, Risa; Yoshimoto, Koichi; Nakajima, Akihiro; Okuyama, Kiyoshi; Iwase, Osamu; Yamada, Yasuhiko

    2015-03-01

    5-HT(3) receptor antagonists are widely used as antiemetic agents in clinical setting, of which palonosetron, with a long elimination half life (t(1/2)), has recently become available. It is important to evaluate the concentration of serotonin when investigating the antiemetic effects of 5-HT(3) receptor antagonists, as those effects are not based solely on the t(1/2) value. We theoretically evaluated the antiemetic effects of three 5-HT(3) receptor antagonists (granisetron, azasetron, palonosetron) on cisplatin-induced nausea and vomiting by estimating the time course of the 5-HT(3) receptor occupancy of serotonin. We estimated the 5-HT(3) receptor occupancy of serotonin in the small intestine, based on the time course of plasma concentration of each 5-HT(3) receptor antagonist and the time course of concentration of serotonin near the 5-HT(3) receptor in the small intestine after administration of cisplatin. The antiemetic effect of each 5-HT(3) receptor antagonist was evaluated based on the normal level of 5-HT(3) receptor occupancy of serotonin. Our results suggest that an adequate antiemetic effect will be provided when a dose of 75 mg/m(2) of cisplatin is given to patients along with any single administration of granisetron, azasetron, or palonosetron at a usual dose. On the other hand, the 5-HT(3) receptor occupancy of serotonin was found to be significantly lower than normal for several days after administration of palonosetron, as compared to granisetron and azasetron, indicating that constipation may be induced. Our results show that granisetron, azasetron, and palonosetron each have an adequate antiemetic effect after administration of 75 mg/m(2) of cisplatin.

  4. 2-Amino-6-chloro-3,4-dihydroquinazoline: A novel 5-HT3 receptor antagonist with antidepressant character.

    PubMed

    Dukat, Małgorzata; Alix, Katie; Worsham, Jessica; Khatri, Shailesh; Schulte, Marvin K

    2013-11-01

    2-Amino-6-chloro-3,4-dihydroquinazoline HCl (A6CDQ, 4) binds at 5-HT3 serotonin receptors and displays antidepressant-like action in the mouse tail suspension test (TST). Empirically, 4 was demonstrated to be a 5-HT3 receptor antagonist (two-electrode voltage clamp recordings using frog oocytes; IC50=0.26μM), and one that should readily penetrate the blood-brain barrier (logP=1.86). 5-HT3 receptor antagonists represent a potential approach to the development of new antidepressants, and 4 is an example of a structurally novel 5-HT3 receptor antagonist that is active in a preclinical antidepressant model (i.e., the mouse TST).

  5. 5-HT3 receptor influences the washing phenotype and visual organization in obsessive-compulsive disorder supporting 5-HT3 receptor antagonists as novel treatment option.

    PubMed

    Lennertz, Leonhard; Wagner, Michael; Grabe, Hans Jörgen; Franke, Petra E; Guttenthaler, Vera; Rampacher, Friederike; Schulze-Rauschenbach, Svenja; Vogeley, Andrea; Benninghoff, Jens; Ruhrmann, Stephan; Pukrop, Ralf; Klosterkötter, Joachim; Falkai, Peter; Maier, Wolfgang; Mössner, Rainald

    2014-01-01

    A role of the HTR3A-E genes in obsessive-compulsive disorder (OCD) can be expected based on promising effects of 5-HT3 receptor antagonists as adjunctive treatment of OCD. We therefore genotyped six common coding or promoter variants within the HTR3A-E genes in a case-control-sample consisting of N=236 OCD patients and N=310 control subjects and in N=58 parent-child-trios. Given the heterogeneous OCD phenotype, we also investigated OCD symptom dimensions and cognitive endophenotypes in subsamples. OCD patients scoring high for the washing subtype were significantly more likely to carry the c.256G-allele of the HTR3E variant rs7627615 (p=0.0001) as compared to OCD patients low for this symptom dimension. Visual organization was impaired in OCD patients and unaffected relatives as compared to healthy control subjects and carriers of the HTR3E c.256G/c.256G-genotype performed significantly worse (p=0.007). The case-control analyses revealed a nominal significant association of the HTR3D variant rs1000592 (p.H52R) with OCD (p=0.029) which was also evident after combination of the case-control and the trio-results (p=0.024). In male subjects, the variant rs6766410 (p.N163K) located in the HTR3C was significantly associated with OCD (p=0.007). The association findings of the HTR3C and the HTR3E remained significant after correction for the number of variants investigated. These findings indicate a role of common variants of the HTR3A-E genes in OCD and OCD-related phenotypes and further support the use of 5-HT3 receptor antagonists as novel treatment options. The HTR3E gene is a novel candidate gene impacting on the individual expression of OC symptoms and OCD-related cognitive dysfunction.

  6. Comparative Pharmacology and Guide to the Use of the Serotonin 5-HT3 Receptor Antagonists for Postoperative Nausea and Vomiting.

    PubMed

    Kovac, Anthony L

    2016-12-01

    Since the introduction of the serotonin 5-hydroxy tryptamine 3 (5-HT3) receptor antagonists in the early 1990s, the incidence of postoperative nausea and vomiting (PONV) and post-discharge nausea and vomiting (PDNV) has decreased, yet continues to be a problem for the surgical patient. The clinical application of the 5-HT3 receptor antagonists has helped define the approach and role of these antiemetics in the prevention and treatment of PONV and PDNV. Pharmacological and clinical differences exist among these medications resulting in corresponding differences in effectiveness, safety, optimal dosage, time of administration, and use as combination and rescue antiemetic therapy. The clinical application of the 5-HT3 receptor antagonist antiemetics has improved the prevention and treatment of PONV and PDNV. The most recent consensus guidelines for PONV published in 2014 outline the use of these antiemetics. The 5-HT3 receptor antagonists play an important role to help prevent PONV and PDNV in perioperative care pathways such as Enhanced Recovery After Surgery (ERAS). Comparisons and guidelines for use of the 5-HT3 receptor antagonists in relation to the risk for PONV and PDNV are reviewed.

  7. Interaction of pyridostigmine with the 5-HT(3) receptor antagonist ondansetron in guinea pigs

    SciTech Connect

    Capacio, B.R.; Byers, C.E.; Matthews, R.L.; Anderson, D.R.; Anders, J.C.

    1993-05-13

    Serotonin receptor subtype three (5HT3) antagonists, such as the drug ondansetron (OND), have been developed as effective anti-emetic compounds. The purpose of this study was to assess the drug interactions of OND (10, 20 and 30 mg/kg) with the organophosphorus pretreatment compound pyridostigmine (PYR; 0.94 mg/kg) after simultaneous oral administration to guinea pigs. Compatibility was assessed by determining (1) OND pharmacokinetics in the absence (Phase 1) and presence (Phase 2) of pyridostigmine (PYR) and (2) PYR-induced acetylcholinesterase (AChE) inhibition kinetics in the absence (Phase 1) and the presence (Phase 2) of OND. AChE inhibition was examined because it has been shown to be an indicator of PYR efficacy against OP-induced lethality. The pharmacokinetics of OND alone and in the presence of PYR were linear and best described by a one-compartment model with first-order absorption and elimination rate kinetics. For OND 30 mg/kg the K10 was found to be significantly smaller in Phase 2 than Phase 1 (p < 0.05).

  8. Eegraphic and behavioural effects of ondansetron, a 5HT3 antagonist, in rabbits.

    PubMed

    Bo, P; Marchioni, E; Soragna, D; Murelli, R; Savoldi, F

    1993-09-01

    1. EEGraphic and behavioural effects of ondansetron, a 5HT3 antagonist, have been studied in the rabbit. Subsequently we tested the neurophysiological and behavioural interactions between ondansetron and L-5-HTP induced serotonergic syndrome. 2. The drug produced a dose-dependent (0.001, 0.01, 0.1 mg/kg i.v.) increase in the cortical power density spectrum, particularly in the range of the lowest frequencies bands. This effect is expression of cortical synchronization. 3. The lowest and mild dose, but not the highest, failed to produce behavioural sedation and to inhibit the arousal induced by vibroacustical stimulation. 4. L-5-HTP (10 mg/kg i.v.) administration generated a typical EEGraphic-behavioural pattern characterized by a decrease of cortical power spectrum density and stereotyped movements. The EEGraphic effects were significantly suppressed by administration of mild and higher doses of ondansetron, while the behavioural effects were inhibited by all doses tested. 5. It is concluded that ondansetron acts with considerably efficacy on central nervous system. The administration of low and mild doses shows a singular dissociation between EEGraphic and behavioural actions. The inhibition of the L-5-HTP behavioural syndrome by ondansetron suggests that this drug acts on behaviour only when there is an altered physiological pattern.

  9. Impact of 5-HT3 receptor antagonists on chemotherapy-induced nausea and vomiting: a retrospective cohort study

    PubMed Central

    2012-01-01

    Background 1st generation 5-hydroxytryptamine receptor antagonists (5-HT3 RAs), and palonosetron, a 2nd generation 5-HT3 RA, are indicated for the prevention of chemotherapy (CT)-induced nausea and vomiting (CINV) associated with moderately (MEC) and highly emetogenic CT agents (HEC). This study explores the impact of step therapy policies requiring use of an older 5-HT3 RA before palonosetron on risk of CINV associated with hospital or emergency department (ED) admissions. Methods Patients who received cyclophosphamide post breast cancer (BC) surgery or who were diagnosed with lung cancer on carboplatin (LC-carboplatin) or cisplatin (LC-cisplatin) were selected from PharMetrics’ (IMS LifeLink) claims dataset (2005-2008). Patients were followed for 6 months from initial CT administration for CINV events identified through ICD-9-CM codes. Patients were grouped into those initiated with older, generic 5-HT3 RAs (ondansetron, granisetron, and dolasetron) and those initiated and maintained on palonosetron throughout study follow-up. CINV events and CINV days were analyzed using multivariate regressions controlling for demographic and clinical variables. Results Eligible patients numbered 3,606 in BC, 4,497 in LC-carboplatin and 1,154 in LC-cisplatin cohorts, with 52%, 40%, and 34% in the palonosetron group, respectively. There was no significant difference between the two 5-HT3 RA groups in age or Charlson Comorbidity Index among the two MEC cohorts (BC and LC-carboplatin). Among the LC-cisplatin cohort, palonosetron users were older with more males than the older 5-HT3 RA group (age: 60.1 vs. 61.3; males, 66.9% vs. 56.9%). Compared to the older 5-HT3 RAs, the palonosetron groups incurred 22%-51% fewer 5-HT3 RA pharmacy claims, had fewer patients with CINV events (3.5% vs. 5.5% in BC, 9.5% vs. 12.8% in LC-carboplatin, 16.4% vs. 21.7% in LC-cisplatin), and had lower risk for CINV events (odds ratios 0.62, 0.71, or 0.71, respectively; p < 0.05). The BC and LC

  10. MDL72222, a serotonin 5-HT3 receptor antagonist, blocks MDMA's ability to establish a conditioned place preference.

    PubMed

    Bilsky, E J; Reid, L D

    1991-06-01

    Methylenedioxymethamphetamine (MDMA) has previously been shown to produce a positive conditioned place preference (CPP) among rats. Here the effects of doses of a specific 5-HT3 antagonist, MDL72222, on MDMA's ability to produce a CPP were assessed. A dose of MDL72222 (0.03 mg/kg) blocked the establishment of a MDMA CPP. These results support the suggestions that compounds affecting the 5-HT3 receptor may be of particular interest in studying the pharmacology of self-administered drugs.

  11. The antiemetic 5-HT3 receptor antagonist Palonosetron inhibits substance P-mediated responses in vitro and in vivo.

    PubMed

    Rojas, Camilo; Li, Ying; Zhang, Jie; Stathis, Marigo; Alt, Jesse; Thomas, Ajit G; Cantoreggi, Sergio; Sebastiani, Silvia; Pietra, Claudio; Slusher, Barbara S

    2010-11-01

    Palonosetron is the only 5-HT(3) receptor antagonist approved for the treatment of delayed chemotherapy-induced nausea and vomiting (CINV) in moderately emetogenic chemotherapy. Accumulating evidence suggests that substance P (SP), the endogenous ligand acting preferentially on neurokinin-1 (NK-1) receptors, not serotonin (5-HT), is the dominant mediator of delayed emesis. However, palonosetron does not bind to the NK-1 receptor. Recent data have revealed cross-talk between the NK-1 and 5HT(3) receptor signaling pathways; we postulated that if palonosetron differentially inhibited NK-1/5-HT(3) cross-talk, it could help explain its efficacy profile in delayed emesis. Consequently, we evaluated the effect of palonosetron, granisetron, and ondansetron on SP-induced responses in vitro and in vivo. NG108-15 cells were preincubated with palonosetron, granisetron, or ondansetron; antagonists were removed and the effect on serotonin enhancement of SP-induced calcium release was measured. In the absence of antagonist, serotonin enhanced SP-induced calcium-ion release. After preincubation with palonosetron, but not ondansetron or granisetron, the serotonin enhancement of the SP response was inhibited. Rats were treated with cisplatin and either palonosetron, granisetron, or ondansetron. At various times after dosing, single neuronal recordings from nodose ganglia were collected after stimulation with SP; nodose ganglia neuronal responses to SP were enhanced when the animals were pretreated with cisplatin. Palonosetron, but not ondansetron or granisetron, dose-dependently inhibited the cisplatin-induced SP enhancement. The results are consistent with previous data showing that palonosetron exhibits distinct pharmacology versus the older 5-HT(3) receptor antagonists and provide a rationale for the efficacy observed with palonosetron in delayed CINV in the clinic.

  12. QoL evaluation of olanzapine for chemotherapy-induced nausea and vomiting comparing with 5-HT3 receptor antagonist.

    PubMed

    Liu, J; Tan, L; Zhang, H; Li, H; Liu, X; Yan, Z; Chen, J; Yang, H; Zhang, D

    2015-05-01

    This study evaluated the efficacy of olanzapine in preventing chemotherapy-induced nausea and vomiting (CINV) and improving the quality of life (QoL) of patients with cancer during chemotherapy. Two hundred twenty-nine patients with cancer who received chemotherapy from January 2008 to August 2008 were enrolled, and they were randomised to receive olanzapine or a 5-HT3 receptor antagonist. The patients completed a CINV questionnaire once daily on days 1-5 and a QoL questionnaire on days 0 and 6. The complete response (CR) rates for nausea (76.85% versus 46.2%) and vomiting (84.3% versus 67.6%) were significantly higher in the olanzapine group than in the 5-HT3 receptor antagonist group for delayed CINV but not for acute CINV. The CR rates for nausea (76.85% versus 44.44%) and vomiting (85.95% versus 67.59%) were also significantly higher in the olanzapine group for the 5 days post-chemotherapy. After chemotherapy, global health status, emotional functioning, and insomnia were improved in the olanzapine group but worsened in the 5-HT3 receptor antagonist group, whereas cognitive functioning and appetite loss were unchanged. Moreover, olanzapine significantly improved global health status, emotional functioning, social functioning, fatigue, nausea/vomiting, insomnia, and appetite loss. Olanzapine improved the QoL of patients with cancer during chemotherapy, in part by reducing the incidence of delayed CINV. © 2014 John Wiley & Sons Ltd.

  13. Effects of repeated daily treatments with a 5-HT3 receptor antagonist on dopamine neurotransmission and functional activity of 5-HT3 receptors within the nucleus accumbens of Wistar rats.

    PubMed

    Liu, Wen; Thielen, Richard J; McBride, William J

    2006-06-01

    A previous study indicated that pretreatment with repeated daily injections of serotonin-3 (5-HT3) receptor antagonists subsequently reduced the effectiveness of the 5-HT3 antagonists to attenuate ethanol intake under 24-h free-choice conditions; one possibility to account for this is that the functional activity of the 5-HT3 receptor may have been altered by prior treatment with the antagonists. The present experiments were conducted to examine the effects of local perfusion of the 5-HT3 agonist 1-(m-chlorophenyl)-biguanide (CPBG) on the extracellular levels of dopamine (DA) in the nucleus accumbens (ACB) and ventral tegmental area (VTA) of adult male Wistar rats that had received repeated daily injections of the 5-HT3 antagonist, MDL 72222 (MDL). In vivo microdialysis was used to test the hypothesis that alterations in 5-HT3 receptor function have occurred with repeated antagonist injections. One group was given daily injections of MDL (1 mg/kg, s.c.) for 10 consecutive days (MDL group), and the other group was administered saline for 10 days (saline group). On the day after the last treatment, rats were implanted with a unilateral guide cannula aimed at either the ACB or VTA. Two days later, the microdialysis probe was inserted into the guide cannula; on the next day, microdialysis experiments were conducted to determine the extracellular levels of DA in the ACB or VTA. Local perfusion of CPBG (17.5, 35, 70 microM) in the ACB significantly stimulated DA release in the saline- and MDL-treated animals. In terms of percent baseline, the CPBG-stimulated DA release was higher in the MDL-treated group than in the saline-treated group in both the ACB and VTA; however, on the basis of the extracellular concentration, there were no significant differences in the ACB between the two groups. Using the no-net-flux microdialysis, it was determine that the basal extracellular concentration of DA in the ACB was approximately 60% lower in the MDL group than saline group; there

  14. Inhibition of temporomandibular joint input to medullary dorsal horn neurons by 5HT3 receptor antagonist in female rats.

    PubMed

    Okamoto, K; Katagiri, A; Rahman, M; Thompson, R; Bereiter, D A

    2015-07-23

    Repeated forced swim (FS) conditioning enhances nociceptive responses to temporomandibular joint (TMJ) stimulation in female rats. The basis for FS-induced TMJ hyperalgesia remains unclear. To test the hypothesis that serotonin 3 receptor (5HT3R) mechanisms contribute to enhanced TMJ nociception after FS, ovariectomized female rats were treated with estradiol and subjected to FS for three days. On day 4, rats were anesthetized with isoflurane and TMJ-responsive neurons were recorded from superficial and deep laminae at the trigeminal subnucleus caudalis/upper cervical (Vc/C1-2) region and electromyographic (EMG) activity was recorded from the masseter muscle. Only Vc/C1-2 neurons activated by intra-TMJ injections of ATP were included for further analysis. Although neurons in both superficial and deep laminae were activated by ATP, only neurons in deep laminae displayed enhanced responses after FS. Local application of the 5HT3R antagonist, ondansetron (OND), at the Vc/C1-2 region reduced the ATP-evoked responses of neurons in superficial and deep laminae and reduced the EMG response in both sham and FS rats. OND also decreased the spontaneous firing rate of neurons in deep laminae and reduced the high-threshold convergent cutaneous receptive field area of neurons in superficial and deep laminae in both sham and FS rats. These results revealed that central application of a 5HT3R antagonist, had widespread effects on the properties of TMJ-responsive neurons at the Vc/C1-2 region and on jaw muscle reflexes under sham and FS conditions. It is concluded that 5HT3R does not play a unique role in mediating stress-induced hyperalgesia related to TMJ nociception.

  15. Antiemetic effects of YM060, a potent and selective serotonin (5HT)3-receptor antagonist, in ferrets and dogs.

    PubMed

    Kamato, T; Miyata, K; Ito, H; Yuki, H; Yamano, M; Honda, K

    1991-11-01

    YM060, (R)-5-[(1-methyl-3-indolyl)carbonyl]-4,5,6,7-tetrahydro-1H-benzimidazole hydrochloride, is a new serotonin (5HT)3-receptor antagonist. We examined the effects of YM060 on chemotherapeutic agent-, apomorphine- and copper sulfate-induced emesis. Intravenous YM060 potently prevented cisplatin (10 mg/kg, i.v.)-induced emesis with ED50 values of 0.06 (0.05-0.07) micrograms/kg, i.v. in ferrets. Based on the ED50 values, YM060 was 300, 20 and 100 times more potent than ondansetron, granisetron and the S-isomer of YM060, respectively. The relative potencies of these drugs described above were similar to those in the previously reported 5HT3-receptor antagonism. YM060 given orally also potently inhibited cisplatin (10 mg/kg, i.p.)- and cyclophosphamide (200 mg/kg, i.p.)-induced emesis in ferrets with ED50 values of 0.1 (0.09-0.11) and 0.02 (0.16-0.27) micrograms/kg, p.o., respectively. All tested 5HT3-receptor antagonists including YM060 failed to prevent apomorphine (0.1 mg/kg, s.c.)-induced emesis in dogs and copper sulfate (1%, 10 ml, p.o.)-induced emesis in ferrets. Our data indicate that YM060 is a highly potent inhibitor of chemotherapeutic agent-induced emesis and that the antiemetic effect of YM060 may be depend on 5HT3-receptor antagonism.

  16. Inhibition of temporomandibular joint input to medullary dorsal horn neurons by 5HT3 receptor antagonist in female rats

    PubMed Central

    Okamoto, Keiichiro; Katagiri, Ayano; Rahman, Mostafeezur; Thompson, Randall; Bereiter, David A.

    2015-01-01

    Repeated forced swim (FS) conditioning enhances nociceptive responses to temporomandibular joint (TMJ) stimulation in male and female rats. The basis for FS-induced TMJ hyperalgesia remains unclear. To test the hypothesis that serotonin 3 receptor (5HT3R) mechanisms contribute to enhanced TMJ nociception after FS, ovariectomized female rats were treated with estradiol and subjected to FS for three days. On day 4, rats were anesthetized with isoflurane and TMJ-responsive neurons were recorded from superficial and deep laminae at the trigeminal subnucleus caudalis/upper cervical (Vc/C1–2) region and electromyographic (EMG) activity was recorded from the masseter muscle. Only Vc/C1–2 neurons activated by intra-TMJ injections of ATP were included for further analysis. Although neurons in both superficial and deep laminae were activated by ATP, only neurons in deep laminae displayed enhanced responses after FS. Local application of the 5HT3R antagonist, ondansetron (OND), at the Vc/C1–2 region reduced the ATP-evoked responses of neurons in superficial and deep laminae and reduced the EMG response in both sham and FS rats. OND also decreased the spontaneous firing rate of neurons in deep laminae and reduced the high threshold convergent cutaneous receptive field area of neurons in superficial and deep laminae in both sham and FS rats. These results revealed that central application of a 5HT3R antagonist, had widespread effects on the properties of TMJ-responsive neurons at the Vc/C1–2 region and on jaw muscle reflexes under sham and FS conditions. It is concluded that 5HT3R does not play a unique role in mediating stress-induced hyperalgesia related to TMJ nociception. PMID:25913635

  17. Effects of DAU 6215, a novel 5-hydroxytryptamine3 (5-HT3) antagonist on electrophysiological properties of the rat hippocampus.

    PubMed Central

    Passani, M. B.; Pugliese, A. M.; Azzurrini, M.; Corradetti, R.

    1994-01-01

    1. The aim of the present study was to test the effects of DAU 6215 (endo-N-(8-methyl-8-azabicyclo-[3.2.1]-octo-3-yl)-2,3-dihydro-2-ox o-1H- benzimidazole-1-carboxamide carboxamide hydrochloride), a newly synthesized, selective 5-hydroxytryptamine3 (5-HT3) antagonist, on the cell membrane properties and on characterized 5-HT-mediated responses of pyramidal neurones in the hippocampal CA1 region. 2. Administration of DAU 6215, even at concentrations several hundred fold its Ki, did not affect the cell membrane properties of pyramidal neurones, nor modify extracellularly recorded synaptic potentials, evoked by stimulating the Schaffer's collaterals. 3. Micromolar concentrations (15-30 microM) of 5-HT elicited several responses in pyramidal neurones that are mediated by distinct 5-HT receptor subtypes. DAU 6215 did not antagonize the 5-HT1A-induced membrane hyperpolarization and conductance increase, a response that was blocked by the selective 5-HT1A antagonist NAN-190 (1-(2-methoxyphenyl)-4-[4-(2-phtalamido)butyl- piperazine). Similarly, DAU 6215 did not affect the membrane depolarization and decrease in amplitude of the afterhyperpolarization, elicited by the activation of putative 5-HT4 receptors. 4. 5-HT increased the frequency of spontaneous postsynaptic potentials (s.p.s.ps) recorded in pyramidal neurones loaded with chloride. In agreement with previous observations, most of the s.p.s.ps were reversed GABAergic events, produced by the activation of 5-HT3 receptors on interneurones, because they persisted in the presence of the glutamate NMDA and non NMDA antagonists, D-aminophosphonovaleric acid (APV; 50 microM) and 6,7-dinitroquinoxaline-2,3-dione (DNQX; 25 microM), and were elicited by the selective 5-HT3 agonist, 2-methyl-5-HT (2-Me-5-HT, 50 microM).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8075890

  18. Superagonist, Full Agonist, Partial Agonist, and Antagonist Actions of Arylguanidines at 5-Hydroxytryptamine-3 (5-HT3) Subunit A Receptors.

    PubMed

    Alix, Katie; Khatri, Shailesh; Mosier, Philip D; Casterlow, Samantha; Yan, Dong; Nyce, Heather L; White, Michael M; Schulte, Marvin K; Dukat, Małgorzata

    2016-11-16

    Introduction of minor variations to the substitution pattern of arylguanidine 5-hydroxytryptamine-3 (5-HT3) receptor ligands resulted in a broad spectrum of functionally-active ligands from antagonist to superagonist. For example, (i) introduction of an additional Cl-substituent(s) to our lead full agonist N-(3-chlorophenyl)guanidine (mCPG, 2; efficacy % = 106) yielded superagonists 7-9 (efficacy % = 186, 139, and 129, respectively), (ii) a positional isomer of 2, p-Cl analog 11, displayed partial agonist actions (efficacy % = 12), and (iii) replacing the halogen atom at the meta or para position with an electron donating OCH3 group or a stronger electron withdrawing (i.e., CF3) group resulted in antagonists 13-16. We posit based on combined mutagenesis, crystallographic, and computational analyses that for the 5-HT3 receptor, the arylguanidines that are better able to simultaneously engage the primary and complementary subunits, thus keeping them in close proximity, have greater agonist character while those that are deficient in this ability are antagonists.

  19. Block of the delayed rectifier current (IK) by the 5-HT3 antagonists ondansetron and granisetron in feline ventricular myocytes.

    PubMed

    de Lorenzi, F G; Bridal, T R; Spinelli, W

    1994-10-01

    1. We investigated the effects of two 5-HT3 antagonists, ondansetron and granisetron, on the action potential duration (APD) and the delayed rectifier current (IK) of feline isolated ventricular myocytes. Whole-cell current and action potential recordings were performed at 37 degrees C with the patch clamp technique. 2. Ondansetron and granisetron blocked IK with a KD of 1.7 +/- 1.0 and 4.3 +/- 1.7 microM, respectively. At a higher concentration (30 microM), both drugs blocked the inward rectifier (IKl). 3. The block of IK was dependent on channel activation. Both drugs slowed the decay of IK tail currents and produced a crossover with the pre-drug current trace. These results are consistent with block and unblock from the open state of the channel. 4. Granisetron showed an intrinsic voltage-dependence as the block increased with depolarization. The equivalent voltage-dependency of block (delta) was 0.10 +/- 0.04, suggesting that granisetron blocks from the intracellular side at a binding site located 10% across the transmembrane electrical field. 5. Ondansetron (1 microM) and granisetron (3 microM) prolonged APD by about 30% at 0.5 Hz. The prolongation of APD by ondansetron was abolished at faster frequencies (3 Hz) showing reverse rate dependence. 6. In conclusion, the 5-HT3 antagonists, ondansetron and granisetron, are open state blockers of the ventricular delayed rectifier and show a clear class III action.

  20. [Effect of the 5-HT3 receptor antagonist granisetron on estramustine phosphate sodium (Estracyt)-induced emesis in ferrets].

    PubMed

    Higashioka, Masaya; Yamaguchi, Emi; Takatori, Shingo; Tanaka, Mitsushi; Kyoi, Takashi

    2010-07-01

    Estracyt(R) is an antimitotic drug used for the treatment of prostate cancer, and its most common adverse effects are nausea and vomiting. In this study, we investigated the effect of a 5-HT3 receptor antagonist, granisetron, on emesis induced in ferrets by estramustine phosphate sodium (EMP), the active ingredient of Estracyt. To clarify the mechanism of action of EMP-induced emesis, we also investigated the effect of EMP on the release of serotonin (5-HT) in the isolated rat ileum. EMP (3 mg/kg, per os) induced 75.3+/-10.2 retching episodes and 7.5+/-1.3 vomiting episodes during a 2-h observation period. The latency to the first emetic response was 58.0+/-13.5 min. Granisetron (0.1 mg/kg, per os) administered 1 h before the administration of EMP reduced the number of EMP-induced retching and vomiting episodes to 1.3+/-1.3 and 1.0+/-1.0, respectively, and prolonged the latency by a factor of almost two. EMP (10-5 and 10-4 M) increased 5-HT release from isolated rat ileum, and 10 -7 M granisetron almost completely inhibited the increase induced by 10-4 M EMP. These results suggest that EMP induces nausea and vomiting via 5-HT release from the ileum, and that 5-HT3 receptor antagonists may be useful to prevent gastrointestinal adverse effects that occur during treatment with Estracyt.

  1. The 5-HT3 receptor antagonist, ondansetron, blocks the development and expression of ethanol-induced locomotor sensitization in mice.

    PubMed

    Umathe, Sudhir N; Bhutada, Pravinkumar S; Raut, Vivek S; Jain, Nishant S; Mundhada, Yogita R

    2009-02-01

    Manipulation of the serotonergic system has been shown to alter ethanol sensitization. Ondansetron is a 5-HT3 receptor antagonist, reported to attenuate cocaine and methamphetamine-induced behavioral sensitization, but no reports are available on its role in ethanol-induced behavioral sensitization. Therefore, an attempt has been made to assess this issue by using an earlier used animal model of ethanol-induced locomotor sensitization. Results indicated that ondansetron (0.25-1.0 mg/kg, subcutaneously) given before the challenge dose of ethanol (2.4 g/kg, intraperitoneally) injection, significantly and dose dependently attenuated the expression of sensitization. In addition, ondansetron (1.0 mg/kg, subcutaneously) given before ethanol injection on days 1, 4, 7, and 10 significantly blocked the development (days 1, 4, 7, and 10), and expression (day 15) of sensitization to the locomotor stimulant effect of ethanol injection. Ondansetron had no effect per se on locomotor activity and did not affect blood ethanol levels. Therefore, the results raise the possibility that ondansetron blocked the development and expression of ethanol-induced locomotor sensitization by acting on 5-HT3 receptors.

  2. A 5-HT3 receptor antagonist potentiates the behavioral, neurochemical and electrophysiological actions of an SSRI antidepressant.

    PubMed

    Bétry, C; Overstreet, D; Haddjeri, N; Pehrson, A L; Bundgaard, C; Sanchez, C; Mørk, A

    2015-04-01

    More effective treatments for major depression are needed. We studied if the selective 5-HT3 receptor antagonist ondansetron can potentiate the antidepressant potential of the selective serotonin (5-HT) reuptake inhibitor (SSRI) paroxetine using behavioral, neurochemical and electrophysiological methods. Flinders Sensitive Line (FSL) rats, treated with ondansetron, and/or a sub-effective dose of paroxetine, were assessed in the forced swim test. The effects of an acute intravenous administration of each compound alone and in combination were evaluated with respect to 5-HT neuronal firing rate in the dorsal raphe nucleus (DRN). Effects of s.c. administration of the compounds alone and in combination on extracellular levels of 5-HT were assessed in the ventral hippocampus of freely moving rats by microdialysis. The results showed that ondansetron enhanced the antidepressant activity of paroxetine in the forced swim test. It partially prevented the suppressant effect of paroxetine on DRN 5-HT neuronal firing and enhanced the paroxetine-induced increase of hippocampal extracellular 5-HT release. These findings indicate that 5-HT3 receptor blockade potentiates the antidepressant effects of SSRIs. Since both paroxetine and ondansetron are used clinically, it might be possible to validate this augmentation strategy in depressed patients.

  3. Identification of Glycyrrhiza as the rikkunshito constituent with the highest antagonistic potential on heterologously expressed 5-HT3A receptors due to the action of flavonoids

    PubMed Central

    Herbrechter, Robin; Ziemba, Paul M.; Hoffmann, Katrin M.; Hatt, Hanns; Werner, Markus; Gisselmann, Günter

    2015-01-01

    The traditional Japanese phytomedicine rikkunshito is traditionally used for the treatment of gastrointestinal motility disorders, cachexia and nausea. These effects indicate 5-HT3 receptor antagonism, due to the involvement of these receptors in such pathophysiological processes. E.g., setrons, specific 5-HT3 receptor antagonists are the strongest antiemetics, developed so far. Therefore, the antagonistic effects of the eight rikkunshito constituents at heterologously expressed 5-HT3Areceptors were analyzed using the two-electrode voltage-clamp technique. The results indicate that tinctures from Aurantii, Ginseng, Zingiberis, Atractylodis and Glycyrrhiza inhibited the 5-HT3A receptor response, whereas the tinctures of Poria cocos, Jujubae and Pinellia exhibited no effect. Surprisingly, the strongest antagonism was found for Glycyrrhiza, whereas the Zingiberis tincture, which is considered to be primarily responsible for the effect of rikkunshito, exhibited the weakest antagonism of 5-HT3A receptors. Rikkunshito contains various vanilloids, ginsenosides and flavonoids, a portion of which show an antagonistic effect on 5-HT3 receptors. A screening of the established ingredients of the active rikkunshito constituents and related substances lead to the identification of new antagonists within the class of flavonoids. The flavonoids (-)-liquiritigenin, glabridin and licochalcone A from Glycyrrhiza species were found to be the most effective inhibitors of the 5-HT-induced currents in the screening. The flavonoids (-)-liquiritigenin and hesperetin from Aurantii inhibited the receptor response in a non-competitive manner, whereas glabridin and licochalcone A exhibited a potential competitive antagonism. Furthermore, licochalcone A acts as a partial antagonist of 5-HT3A receptors. Thus, this study reveals new 5-HT3A receptor antagonists with the aid of increasing the comprehension of the complex effects of rikkunshito. PMID:26191003

  4. The effect of ondansetron, a 5-HT3 receptor antagonist, in chronic fatigue syndrome: a randomized controlled trial.

    PubMed

    The, Gerard K H; Bleijenberg, Gijs; Buitelaar, Jan K; van der Meer, Jos W M

    2010-05-01

    Accumulating data support the involvement of the serotonin (5-hydroxytryptamine [5-HT]) system in the pathophysiology of chronic fatigue syndrome. Neuropharmacologic studies point to a hyperactive 5-HT system, and open-label treatment studies with 5-HT(3) receptor antagonists have shown promising results. In this randomized controlled clinical trial, the effect of ondansetron, a 5-HT(3) receptor antagonist, was assessed on fatigue severity and functional impairment in adult patients with chronic fatigue syndrome. A randomized, placebo-controlled, double-blind clinical trial was conducted at Radboud University Nijmegen Medical Centre, The Netherlands. Sixty-seven adult patients who fulfilled the US Centers for Disease Control and Prevention (CDC) criteria for chronic fatigue syndrome and who were free from current psychiatric comorbidity participated in the clinical trial. Participants received either ondansetron 16 mg per day or placebo for 10 weeks. The primary outcome variables were fatigue severity (Checklist Individual Strength fatigue severity subscale [CIS-fatigue]) and functional impairment (Sickness Impact Profile-8 [SIP-8]). The effect of ondansetron was assessed by analysis of covariance. Data were analyzed on an intention-to-treat basis. All patients were recruited between June 2003 and March 2006. Thirty-three patients were allocated to the ondansetron condition, 34 to the placebo condition. The 2 groups were well matched in terms of age, sex, fatigue severity, functional impairment, and CDC symptoms. Analysis of covariance showed no significant differences between the ondansetron- and placebo-treated groups during the 10-week treatment period in fatigue severity and functional impairment. This clinical trial demonstrates no benefit of ondansetron compared to placebo in the treatment of chronic fatigue syndrome. www.trialregister.nl: ISRCTN02536681. ©Copyright 2010 Physicians Postgraduate Press, Inc.

  5. Spatial orientation of the antagonist granisetron in the ligand-binding site of the 5-HT3 receptor.

    PubMed

    Yan, Dong; White, Michael M

    2005-08-01

    The serotonin type 3 receptor (5-HT(3)R) is a member of the cys-loop ligand-gated ion channel (LGIC) superfamily. Like almost all membrane proteins, high-resolution structural data are unavailable for this class of receptors. We have taken advantage of the high degree of homology between LGICs and the acetylcholine binding protein (AChBP) from the freshwater snail Lymnea stagnalis, for which high-resolution structural data are available, to create a structural model for the extracellular (i.e., ligand-binding) domain of the 5-HT(3)R and to perform a series of ligand docking experiments to delineate the architecture of the ligand-binding site. Structural models were created using homology modeling with the AChBP as a template. Docking of the antagonist granisetron was carried out using a Lamarckian genetic algorithm to produce models of ligand-receptor complexes. Two energetically similar conformations of granisetron in the binding site were obtained from the docking simulations. In one model, the indazole ring of granisetron is near Trp90 and the tropane ring is near Arg92; in the other, the orientation is reversed. We used double-mutant cycle analysis to determine which of the two orientations is consistent with experimental data and found that the data are consistent with the model in which the indazole ring of granisetron interacts with Arg92 and the tropane ring interacts with Trp90. The combination of molecular modeling with double-mutant cycle analysis offers a powerful approach for the delineation of the architecture of the ligand-binding site.

  6. Effects of 5-HT2B, 5-HT3 and 5-HT4 receptor antagonists on gastrointestinal motor activity in dogs

    PubMed Central

    Morita, Hiroki; Mochiki, Erito; Takahashi, Nobuyuki; Kawamura, Kiyoshi; Watanabe, Akira; Sutou, Toshinaga; Ogawa, Atsushi; Yanai, Mitsuhiro; Ogata, Kyoichi; Fujii, Takaaki; Ohno, Tetsuro; Tsutsumi, Souichi; Asao, Takayuki; Kuwano, Hiroyuki

    2013-01-01

    AIM: To study the effects of 5-hydroxytryptamine (5-HT) receptor antagonists on normal colonic motor activity in conscious dogs. METHODS: Colonic motor activity was recorded using a strain gauge force transducer in 5 dogs before and after 5-HT2B, 5-HT3 and 5-HT4 receptor antagonist administration. The force transducers were implanted on the serosal surfaces of the gastric antrum, terminal ileum, ileocecal sphincter and colon. Test materials or vehicle alone was administered as an intravenous bolus injection during a quiescent period of the whole colon in the interdigestive state. The effects of these receptor antagonists on normal gastrointestinal motor activity were analyzed. RESULTS: 5-HT2B, 5-HT3 and 5-HT4 receptor antagonists had no contractile effect on the fasting canine terminal ileum. The 5-HT3 and 5-HT4 receptor antagonists inhibited phase III of the interdigestive motor complex of the antrum and significantly inhibited colonic motor activity. In the proximal colon, the inhibitory effect was dose dependent. Dose dependency, however, was not observed in the distal colon. The 5-HT2B receptor antagonist had no contractile effect on normal colonic motor activity. CONCLUSION: The 5-HT3 and 5-HT4 receptor antagonists inhibited normal colonic motor activity. The 5-HT2B receptor antagonist had no contractile effect on normal colonic motor activity. PMID:24151388

  7. Systemic injection of p-chloroamphetamine eliminates the effect of the 5-HT3 compounds on learning.

    PubMed

    Hong, E; Meneses, A

    1996-04-01

    There is evidence that 5-HT3 antagonists enhance learning and memory; however, their mechanisms of action are unknown. The aim of the present work was to investigate further the role of 5-HT3 receptors involved in learning, using the specific 5-HT3 agonist 1-(m-chlorophenyl)-biguanide (mCPBG) and the 5-HT3 antagonists ondansetron and tropisetron. p-Chloroamphetamine (PCA) pretreatment was used to determine whether pre- or postsynaptic 5-HT3 receptors are involved in learning. The posttraining intraperitoneal (IP) injection of each drug was analyzed on a lever-press response on autoshaping, which is an associative learning task. The results showed that mCPBG impaired retention of the conditioned response (CR), whereas tropisetron and ondansetron improved it. In other animals, PCA alone did not affect CR but was able to block the effects of the 5-HT3 ligands. The present data suggest that the actions of 5-HT3 compounds could be due to their interaction with presynaptic 5-HT3 receptors.

  8. A nanocomposite material formed by benzofulvene polymer nanoparticles loaded with a potent 5-HT3 receptor antagonist (CR3124)

    NASA Astrophysics Data System (ADS)

    Cappelli, Andrea; Galeazzi, Simone; Zanardi, Iacopo; Travagli, Valter; Anzini, Maurizio; Mendichi, Raniero; Petralito, Stefania; Memoli, Adriana; Paccagnini, Eugenio; Peris, Walter; Giordani, Antonio; Makovec, Francesco; Fresta, Massimo; Vomero, Salvatore

    2010-03-01

    Poly- BF3a, a new hydrophobic polymer obtained by spontaneous polymerization of 1-methylene-3-phenyl-1 H-indene, was found to give nanoparticles characterized by favorable shape and dimensions. Poly- BF3a nanoparticles were loaded with CR3124, a potent 5HT3 antagonist, as a drug model by desolvation methods either in the absence or in the presence of polyethylene glycol (PEG1000) as a wetting agent. The SEM studies showed that the introduction of CR3124 into the preparation led to a variable degree of aggregation-cementation, which afforded a sort of nanocomposite material. In the absence of PEG1000, the drug molecule was found to stay in the amorphous state (DSC studies) when its percentage is not higher than 10% by weight. In vitro release experiments showed that the formation and stability of the dispersion as well as the drug release were remarkably affected by the presence of PEG1000, demonstrating its beneficial effect to the nanoparticle morphology and disaggregation.

  9. Design, synthesis and structure-activity relationship of novel quinoxalin-2-carboxamides as 5-HT3 receptor antagonists for the management of depression.

    PubMed

    Mahesh, Radhakrishnan; Devadoss, Thangaraj; Pandey, Dilip Kumar; Bhatt, Shvetank; Yadav, Shushil Kumar

    2010-11-15

    A novel series of quinoxalin-2-carboxamides were designed based on the ligand-based approach, employing a three-point pharmacophore model; it consists of an aromatic residue and a linking carbonyl group and a basic nitrogen. The target new chemical entities were synthesized from the key intermediate, quinoxalin-2-carboxylic acid, by coupling it with various amines in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) and 1-hydroxybenzotriazole (HOBt). The obtained compounds' structures were confirmed by spectral data. The target new chemical entities were evaluated for their 5-HT(3) receptor antagonisms in longitudinal muscle myenteric plexus preparation from guinea pig ileum against 5-HT(3) agonist, 2-methyl-5-HT, which was expressed in the form of pA(2) value. All the synthesized compounds showed antagonism towards 5-HT(3) receptor; based on this result, a structure-activity relationship was derived, which reveals that the aromatic residue in 5-HT(3) receptor antagonists may have hydrophobic interaction with 5-HT(3) receptor. Regardless of their antagonistic potentials, all the synthesized molecules were screened for their anti-depressant potentials by using forced swim test in mice model; interestingly none of the tested compounds affect the locomotion of mice in the tested dose levels. Compounds with significant pA(2) values exhibited good anti-depressant-like activity as compared to the vehicle-treated group.

  10. Review of palonosetron: emerging data distinguishing it as a novel 5-HT(3) receptor antagonist for chemotherapy-induced nausea and vomiting.

    PubMed

    Saito, Mitsue; Tsukuda, Mamoru

    2010-04-01

    Since the advent of the 5-hydroxytryptamine 3 receptor antagonists (5-HT3RAs) in the 1990s, dramatic improvements have been achieved in the field of antiemetic therapy. The enhanced prevention of delayed and overall chemotherapy-induced nausea and vomiting (CINV) offered by palonosetron, a second-generation 5-HT3RA and aprepitant, the first neurokinin-1 receptor antagonists (NK-1RA) represent the only significant treatment advances in the past decade. While initial trials of single-dose palonosetron indicated a potential benefit over first-generation 5-HT3RAs, only recently have new data become available, increasing the weight of evidence distinguishing it as a new 5-HT3RA in the class. History of antiemetics and palonosetron, including clinical trials and pharmacological research, and literature published between 1981 and 2010 are covered. Unique pharmacological characteristics of palonosetron exhibiting prolonged half-life, high receptor affinity, allosteric interactions and positive cooperativity with 5-HT3 receptor resulting in long-term alteration and internalization of this receptor may explain the clinical observation of palonosetron. This review of recent progress in antiemetic therapy focuses on the newest data on palonosetron and discusses future trials and implications for clinical practice, with the overall goal of learning from history.

  11. Piperazine analogs of naphthyridine-3-carboxamides and indole-2-carboxamides: novel 5-HT3 receptor antagonists with antidepressant-like activity.

    PubMed

    Dhar, Arghya K; Mahesh, Radhakrishnan; Jindal, Ankur; Bhatt, Shvetank

    2015-01-01

    Series of piperazine analogs of naphthyridine-3-carboxamides and indole-2-carboxamides were designed using a ligand-based approach with consideration of the pharmacophoric requirements for 5-HT3 receptor antagonists. The title carboxamides were synthesized using appropriate synthetic routes. Initially, the 5-HT3 receptor antagonistic activity of all the compounds was determined on isolated guinea pig ileum tissue against the 5-HT3 agonist, 2-methyl-5-hydroxytryptamine, which was denoted in the form of pA2 values. The structure-activity relationship regarding the influence of the aromatic part and basic moiety as features in the 5-HT3 pharmacophore was derived. Among all the compounds screened, the piperazine derivatives of indole-2-carboxamide 13i and naphthyridine-3-carboxamide 8h exhibited prominent 5-HT3 receptor antagonism with pA2 values of 7.5 and 7.3, respectively. Subsequent investigation of the antidepressant activities of selected compounds in the mouse forced swim test (FST) led to the identification of the piperazine analogs of indole-2-carboxamide 13i and naphthyridine-3-carboxamide 8h as the most promising compounds. Both 13i and 8h demonstrated significant reduction in the duration of immobility as compared to the control. Importantly, none of the tested compounds affected the baseline locomotion of mice at the tested dose levels.

  12. Comparative efficacy and safety of palonosetron with the first 5-HT3 receptor antagonists for the chemotherapy-induced nausea and vomiting: a meta-analysis.

    PubMed

    Jin, Y; Sun, W; Gu, D; Yang, J; Xu, Z; Chen, J

    2013-01-01

    A number of studies have reported the difference between the 5-HT3 receptor antagonists and palonosetron in preventing the chemotherapy-induced nausea and vomiting (CINV). Through analysing the efficacy and safety in palonosetron-treated patients, it can provide evidence for palonosetron administration. We identified randomised controlled clinical trials comparing palonosetron with the first-generation 5-HT3 receptor antagonists in the prevention of CINV in cancer patients. Nine studies investigated the outcomes in a total of 3463 cases. Compared with the first-generation 5-HT3 receptor antagonists, the cumulative incidences of emesis were significantly reduced in the patients treated with palonosetron (0.25 mg i.v.) on the first day [relative risk (RR) = 1.11, 95% confidence interval (CI): 1.05-1.17], from 2 to 5 days (RR = 1.26, 95% CI: 1.16-1.36) and the overall five days (RR = 1.23, 95% CI: 1.13-1.34). Regarding the drug safety, there was no significant difference between palonosetron-treated group and the first-generation 5-HT3 receptor antagonists-treated group. Results from the analysis suggest that palonosetron is highly effective in preventing nausea and vomiting in the days after administration of moderately or highly emetogenic chemotherapy agents. © 2012 Blackwell Publishing Ltd.

  13. Antidepressant Potential of 5-HT3 Receptor Antagonist, N-n- propyl-3-ethoxyquinoxaline-2-carboxamide (6n).

    PubMed

    Mahesh, R; Bhatt, S; Devadoss, T; Jindal, Ak; Gautam, Bk; Pandey, Dk

    2012-10-01

    The present study was designed to evaluate the antidepressant potential of 5-HT3 receptor antagonist N-n-propyl-3-ethoxyquinoxaline-2-carboxamide (6n). The compound '6n' with optimum log P and pA 2 value identified from a series of compounds synthesized in our laboratory was subjected to forced Swim Test (FST) (1, 2, and 4 mg/kg, i.p) and Tail Suspension Test (TST) (1, 2, and 4 mg/kg, i.p.). The compound '6n' significantly reduced the duration of immobility in mice without affecting the baseline locomotion. Moreover, '6n' (2 mg/kg, i.p.) potentiated the 5-hydroxytryptophan (5-HTP)-induced head twitch responses in mice and '6n' at tested dose (1 and 2 mg/kg, i.p.) reversed the reserpine-induced hypothermia in rats. In interaction studies of '6n' with various standard drugs/ligands using FST, '6n' (1 mg/kg, i.p.) potentiated the antidepressant effect of venlafaxine (4 and 8 mg/kg, i.p.) and fluoxetine (10 and 20 mg/kg, i.p.). Additionally, '6n' (1 and 2 mg/kg, i.p.) influenced the effect of harmane (5 mg/ kg, i.p.) as well as reversed the effect of parthenolide (1 mg/kg, i.p.) by reducing the duration of immobility in FST. Furthermore, '6n' (1 mg/kg, i.p.) potentiated the effect of bupropion (10 and 20 mg/kg, i.p.) in TST. Chronic '6n' (1 and 2 mg/kg, i.p.) treatment attenuated the behavioral abnormalities in olfactory bulbectomized rats. In conclusion, these various findings reiterated the antidepressant-like effects of '6n' in behavioral models of depression.

  14. Antidepressant Potential of 5-HT3 Receptor Antagonist, N-n- propyl-3-ethoxyquinoxaline-2-carboxamide (6n)

    PubMed Central

    Mahesh, R; Bhatt, S; Devadoss, T; Jindal, AK; Gautam, BK; Pandey, DK

    2012-01-01

    The present study was designed to evaluate the antidepressant potential of 5-HT3 receptor antagonist N-n-propyl-3-ethoxyquinoxaline-2-carboxamide (6n). The compound ‘6n’ with optimum log P and pA2 value identified from a series of compounds synthesized in our laboratory was subjected to forced Swim Test (FST) (1, 2, and 4 mg/kg, i.p) and Tail Suspension Test (TST) (1, 2, and 4 mg/kg, i.p.). The compound ‘6n’ significantly reduced the duration of immobility in mice without affecting the baseline locomotion. Moreover, ‘6n’ (2 mg/kg, i.p.) potentiated the 5-hydroxytryptophan (5-HTP)-induced head twitch responses in mice and ‘6n’ at tested dose (1 and 2 mg/kg, i.p.) reversed the reserpine-induced hypothermia in rats. In interaction studies of ‘6n’ with various standard drugs/ligands using FST, ‘6n’ (1 mg/kg, i.p.) potentiated the antidepressant effect of venlafaxine (4 and 8 mg/kg, i.p.) and fluoxetine (10 and 20 mg/kg, i.p.). Additionally, ‘6n’ (1 and 2 mg/kg, i.p.) influenced the effect of harmane (5 mg/ kg, i.p.) as well as reversed the effect of parthenolide (1 mg/kg, i.p.) by reducing the duration of immobility in FST. Furthermore, ‘6n’ (1 mg/kg, i.p.) potentiated the effect of bupropion (10 and 20 mg/kg, i.p.) in TST. Chronic ‘6n’ (1 and 2 mg/kg, i.p.) treatment attenuated the behavioral abnormalities in olfactory bulbectomized rats. In conclusion, these various findings reiterated the antidepressant-like effects of ‘6n’ in behavioral models of depression. PMID:23493308

  15. 5HT3 Antagonists versus Dexamethasone in the Prevention of PONV in Patients Undergoing Laparoscopic Cholecystectomy: A Meta-Analysis of RCTs.

    PubMed

    Zhou, Chengmao; Zhu, Yu; Liu, Zhen; Ruan, Lin

    2016-01-01

    Background. 5HT3 antagonist, an antiemetic alternative to dexamethasone, is an effective drug for the prevention of postoperative nausea and vomiting (PONV). Methods. PubMed and The Cochrane Library (from inception to June 2016) were searched for relevant RCTs (randomized controlled trials). Results. Seven trials, totaling 682 patients, were included in this meta-analysis. This meta-analysis demonstrated that 5HT3 antagonist was as effective as dexamethasone in preventing PONV (RR, 1.12; 95% CI, [0.86, 1.45]; P = 0.40) within 24 hours of laparoscopic cholecystectomy, and no significant heterogeneity was observed among the studies (I(2) = 0%; P = 0.98). During the early postoperative period (0-6 h), 5HT3 antagonists were superior to dexamethasone in reducing POV (RR, 0.31; 95% CI, [0.11, 0.93]; P = 0.04), while, in other postoperative stages (6-12 h, 12-24 h, and 0-24 h), it was not more effective in the prevention of POV than dexamethasone. And no significant difference was found in the prevention of PON between 5HT3 antagonists and dexamethasone at different postoperative periods (0-6 h, 6-12 h, 12-24 h, and 0-24 h). Conclusions. As a result, it is advisable to encourage 5HT3 antagonists as an alternative to dexamethasone for the prevention of PONV in patients undergoing laparoscopic cholecystectomy.

  16. 5HT3 Antagonists versus Dexamethasone in the Prevention of PONV in Patients Undergoing Laparoscopic Cholecystectomy: A Meta-Analysis of RCTs

    PubMed Central

    Zhou, Chengmao; Zhu, Yu; Liu, Zhen

    2016-01-01

    Background. 5HT3 antagonist, an antiemetic alternative to dexamethasone, is an effective drug for the prevention of postoperative nausea and vomiting (PONV). Methods. PubMed and The Cochrane Library (from inception to June 2016) were searched for relevant RCTs (randomized controlled trials). Results. Seven trials, totaling 682 patients, were included in this meta-analysis. This meta-analysis demonstrated that 5HT3 antagonist was as effective as dexamethasone in preventing PONV (RR, 1.12; 95% CI, [0.86, 1.45]; P = 0.40) within 24 hours of laparoscopic cholecystectomy, and no significant heterogeneity was observed among the studies (I2 = 0%; P = 0.98). During the early postoperative period (0–6 h), 5HT3 antagonists were superior to dexamethasone in reducing POV (RR, 0.31; 95% CI, [0.11, 0.93]; P = 0.04), while, in other postoperative stages (6–12 h, 12–24 h, and 0–24 h), it was not more effective in the prevention of POV than dexamethasone. And no significant difference was found in the prevention of PON between 5HT3 antagonists and dexamethasone at different postoperative periods (0–6 h, 6–12 h, 12–24 h, and 0–24 h). Conclusions. As a result, it is advisable to encourage 5HT3 antagonists as an alternative to dexamethasone for the prevention of PONV in patients undergoing laparoscopic cholecystectomy. PMID:27891523

  17. The role of second-generation 5-HT3 receptor antagonists in managing chemotherapy-induced nausea and vomiting in hematological malignancies.

    PubMed

    Schwartzberg, Lee S; Jacobs, Peter; Matsouka, Panagiota; Azevedo, Wellington; Pinto, Antonio

    2012-07-01

    Compared with solid tumor patients, those with hematological malignancies are at particular risk of chemotherapy-induced nausea and vomiting (CINV) because of their young age, exposure to highly-emetogenic induction, consolidation and salvage regimens, the high-dose conditioning regimens used before stem cell transplantation (SCT), and the heavy psychological burden of such treatments. In the absence of prophylaxis, around 75% of patients undergoing SCT experience delayed CINV. With first-generation 5-HT(3) receptor antagonists, only about 20% are completely protected from nausea and vomiting, and this frequent and debilitating adverse event has not been fully addressed. In contrast to solid tumors, there are no internationally agreed guidelines for the prevention and treatment of CINV in hematological malignancies. Work on a consensus is urgently required. The second-generation 5-HT(3) antagonist palonosetron is highly effective in preventing CINV in patients with solid tumors. The extended half-life of this agent and its mechanisms of action including allosteric binding, positive cooperativity and 5-HT(3) receptor internalization, may make it particularly effective in controlling delayed CINV. Although controlled comparisons against first-generation 5HT(3) agents have not yet been conducted in the setting of SCT, available evidence suggests that palonosetron may prove beneficial in preventing CINV in high risk patients with hematological malignancies. Copyright © 2012. Published by Elsevier Ireland Ltd.

  18. Design, synthesis and evaluation of antidepressant activity of novel 2-methoxy 1, 8 naphthyridine 3-carboxamides as 5-HT3 receptor antagonists.

    PubMed

    Mahesh, Radhakrishnan; Dhar, Arghya Kusum; Jindal, Ankur; Bhatt, Shvetank

    2014-05-01

    A series of novel 1,8-naphthyridine-3-carboxamides as 5-HT3 receptor antagonists were synthesized with an intention to explore the antidepressant activity of these compounds. The title carboxamides were designed using ligand-based approach keeping in consideration the structural requirement of the pharmacophore of 5-HT3 receptor antagonists. The compounds were synthesized using appropriate synthetic route from the starting material nicotinamide. 5-HT3 receptor antagonism of all the compounds, which was denoted in the form of pA2 value, was determined in longitudinal muscle myenteric plexus preparation from guinea-pig ileum against 5-HT3 agonist, 2-methyl-5-HT. Compound 8g (2-methoxy-1, 8-naphthyridin-3-yl) (2-methoxy phenyl piperazine-1-yl) methanone was identified as the most active compound, which expressed a pA2 value of 7.67. The antidepressant activity of all the compounds was examined in mice model of forced swim test (FST); importantly, none of the compounds was found to cause any significant changes in the locomotor activity of mice at the tested dose levels. In FST, the compounds with considerably higher pA2 value exhibited promising antidepressant-like activity, whereas compounds with lower pA2 value did not show antidepressant-like activity as compared to the control group. © 2013 John Wiley & Sons A/S.

  19. The effects of varenicline on sensory gating and exploratory behavior with pretreatment with nicotinic or 5-HT3A receptor antagonists.

    PubMed

    Kucinski, Aaron; Wersinger, Scott; Stachowiak, Ewa K; Becker, Chani; Lippiello, Pat; Bencherif, Merouane; Stachowiak, Michal K

    2015-02-01

    Individuals with schizophrenia smoke at high frequency relative to the general population. Despite the harmful effects of cigarette smoking, smoking among schizophrenic patients improves cognitive impairments not addressed or worsened by common neuroleptics. Varenicline, a nonselective neuronal nicotinic receptor (NNR) agonist and full agonist of 5-HT3A receptors, helps reduce smoking among schizophrenic patients. To determine whether varenicline also improves a cognitive symptom of schizophrenia, namely, impaired sensory gating, a transgenic mouse with schizophrenia, th-fgfr1(tk-), was used. Varenicline dose-dependently increased prepulse inhibition (PPI) of the startle response, a measure of sensory gating, in th-fgfr1(tk-) mice and normalized PPI deficits relative to nontransgenic controls. With the highest dose (10 mg/kg), however, there was a robust elevation of PPI and startle response, as well as reduced exploratory behavior in the open field and elevated plus maze. Pretreatment with the nonspecific NNR antagonist mecamylamine attenuated the exaggerated PPI response and, similar to the 5-HT3A receptor antagonist ondansetron, it prevented the reduction in exploratory behavior. Collectively, these results indicate that varenicline at low-to-moderate doses may be beneficial against impaired sensory gating in schizophrenia; however, higher doses may induce anxiogenic effects, which can be prevented with antagonists of NNRs or 5-HT3A receptors.

  20. 5-HT3 and 5-HT4 antagonists inhibit peristaltic contractions in guinea-pig distal colon by mechanisms independent of endogenous 5-HT

    PubMed Central

    Sia, Tiong C.; Whiting, Malcolm; Kyloh, Melinda; Nicholas, Sarah J.; Oliver, John; Brookes, Simon J.; Dinning, Phil G.; Wattchow, David A.; Spencer, Nick J.

    2013-01-01

    Recent studies have shown that endogenous serotonin is not required for colonic peristalsis in vitro, nor gastrointestinal (GI) transit in vivo. However, antagonists of 5-Hydroxytryptamine (5-HT) receptors can inhibit peristalsis and GI-transit in mammals, including humans. This raises the question of how these antagonists inhibit GI-motility and transit, if depletion of endogenous 5-HT does not cause any significant inhibitory changes to either GI-motility or transit? We investigated the mechanism by which 5-HT3 and 5-HT4 antagonists inhibit distension-evoked peristaltic contractions in guinea-pig distal colon. In control animals, repetitive peristaltic contractions of the circular muscle were evoked in response to fixed fecal pellet distension. Distension-evoked peristaltic contractions were unaffected in animals with mucosa and submucosal plexus removed, that were also treated with reserpine (to deplete neuronal 5-HT). In control animals, peristaltic contractions were blocked temporarily by ondansetron (1–10 μM) and SDZ-205–557 (1–10 μM) in many animals. Interestingly, after this temporary blockade, and whilst in the continued presence of these antagonists, peristaltic contractions recovered, with characteristics no different from controls. Surprisingly, similar effects were seen in mucosa-free preparations, which had no detectable 5-HT, as detected by mass spectrometry. In summary, distension-evoked peristaltic reflex contractions of the circular muscle layer of the guinea-pig colon can be inhibited temporarily, or permanently, in the same preparation by selective 5-HT3 and 5-HT4 antagonists, depending on the concentration of the antagonists applied. These effects also occur in preparations that lack any detectable 5-HT. We suggest caution should be exercised when interpreting the effects of 5-HT3 and 5-HT4 antagonists; and the role of endogenous 5-HT, in the generation of distension-evoked colonic peristalsis. PMID:23935564

  1. Dopamine neurotransmission is involved in the attenuating effects of 5-HT3 receptor antagonist MDL 72222 on acute methamphetamine-induced locomotor hyperactivity in mice.

    PubMed

    Yoo, Ji-Hoon; Nam, Yun-Sun; Lee, Seok-Yong; Jang, Choon-Gon

    2008-01-01

    We have previously shown that 5-HT3 receptors are involved in the development and expression of methamphetamine (MAP)-induced locomotor sensitization in mice. In the present study, we further examined whether the dopaminergic system is involved in the attenuating effects of MDL 72222, a 5-HT3 receptor antagonist, on acute MAP-induced locomotor hyperactivity. For this, we examined alterations of dopamine (DA) in the form of D1 receptor, D2 receptor, and dopamine transporter (DAT) binding labeled with [3H]SCH23390 for D1, [3H]raclopride for D2, and [3H]mazindol for DAT binding in the mouse brains with acute MAP exposure or pretreatment of MDL 72222 with MAP. No significant differences were detected in the D1 receptor, D2 receptor, or DAT binding between any of the groups studied. Interestingly, we found increased DA levels in the striatum following acute MAP exposure; these increased levels were reversed by pretreatment with MDL 72222, but did not affect 5-HT levels in the dorsal raphe. Overall, our results suggest that dopamine neurotransmission plays an important role in the attenuating effects of 5-HT3 receptor antagonist MDL 72222 on acute MAP-induced locomotor hyperactivity in mice.

  2. Differential effects of a short-term high-fat diet in an animal model of depression in rats treated with the 5-HT3 receptor antagonist, ondansetron, the 5-HT3 receptor agonist, 2-methyl-5-HT, and the SSRI, fluoxetine.

    PubMed

    Sumaya, Isabel C; Bailey, Dee; Catlett, Susan L

    2016-05-01

    Investigation into the effects of a high-fat diet on depression in the context of 5-HT3 receptor function is important given 5-HT3 antagonism may represent a novel candidate for drug discovery. To more fully understand the relationship between the 5-HT3 receptor system, depression, and high-fat intake, our main interest was to study the short-term effects of a high-fat diet on the 5-HT3 receptor antagonist, ondansetron, and the 5-HT3 receptor agonist, 2-methyl-5-HT, as well as the SSRI, fluoxetine, in an animal model of depression. Male Sprague Dawley rats were fed either a standard diet (11% fat) or a high-fat diet (32.5% fat) for seven days then treated with either fluoxetine (10mg/kg, ip), ondansetron (1mg/kg, ip), 2-methyl-5-HT (3mg/kg, ip), fluoxetine+ondansetron or, 2-methyl-5-HT+ondansetron prior to the Forced Swim Test. In the standard diet group, treatment with the 5HT3 receptor agonist, 2-methyl-5-HT, served to significantly decrease time of immobility as compared to controls thus showing anti-depressive-like effects. Treatment with the 5-HT3 receptor antagonist, ondansetron, served to enhance the anti-depressive like effects of the SSRI, fluoxetine, as treatment with both the SSRI and 5-HT3 receptor antagonist dramatically decreased immobility. Importantly, in the high-fat diet groups, a week of high-fat intake served to: 1) counteract the anti-depressive-like effect of the SSRI, fluoxetine, 2) reverse the anti-depressive-like effect of the 5HT3 receptor agonist, 2-methyl-5-HT and 3) provide protection against the depressive-like effects induced by the Forced Swim Test as rats fed a high-fat diet displayed the lowest amounts of immobility. In the aggregate, these data suggest that both SSRIs and the 5HT3 receptor system are affected by short-term high-fat intake and that a short-term high-fat diet protects against depressive-like effects in an animal model of depression.

  3. Discovery of new anti-depressants from structurally novel 5-HT3 receptor antagonists: design, synthesis and pharmacological evaluation of 3-ethoxyquinoxalin-2-carboxamides.

    PubMed

    Mahesh, Radhakrishnan; Devadoss, Thangaraj; Pandey, Dilip Kumar; Bhatt, Shvetank

    2011-02-15

    A novel series of 3-ethoxyquinoxalin-2-carboxamides were designed as per the pharmacophoric requirements of 5-HT(3) receptor antagonist using ligand-based approach. The desired carboxamides were synthesized from the key intermediate, 3-ethoxyquinoxalin-2-carboxylic acid by coupling with appropriate amines in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) and 1-hydroxybenzotriazole (HOBt). The 5-HT(3) receptor antagonism was evaluated in longitudinal muscle myenteric plexus preparation from guinea pig ileum against 5-HT(3) agonist, 2-methy-5-HT, which was expressed in the form of pA(2) values. Compound 6h (3-ethoxyquinoxalin-2-yl)(4-methylpiperazin-1-yl)methanone was found to be the most active compound, which expressed a pA(2) value of 7.7. In forced swim test, the compounds with higher pA(2) value exhibited good anti-depressant-like activity and compounds with lower pA(2) value failed to show activity as compared to the vehicle-treated group.

  4. Expression of 5-HT3 receptors by extrinsic duodenal afferents contribute to intestinal inhibition of gastric emptying.

    PubMed

    Raybould, Helen E; Glatzle, Jorg; Robin, Carla; Meyer, James H; Phan, Thomas; Wong, Helen; Sternini, Catia

    2003-03-01

    Intestinal perfusion with carbohydrates inhibits gastric emptying via vagal and spinal capsaicin-sensitive afferent pathways. The aim of the present study was to determine the role of 1) 5-hydroxytryptamine (5-HT)(3) receptors (5-HT(3)R) in mediating glucose-induced inhibition of gastric emptying and 2) 5-HT(3)R expression in vagal and spinal afferents in innervating the duodenum. In awake rats fitted with gastric and duodenal cannulas, perfusion of the duodenum with glucose (50 and 100 mg) inhibited gastric emptying. Intestinal perfusion of mannitol inhibited gastric emptying only at the highest concentration (990 mosm/kgH(2)O). Pretreatment with the 5-HT(3)R antagonist tropisetron abolished both glucose- and mannitol-induced inhibition of gastric emptying. Retrograde labeling of visceral afferents by injection of dextran-conjugated Texas Red into the duodenal wall was used to identify extrinsic primary afferents. Immunoreactivity for 5-HT(3)R, visualized with an antibody directed to the COOH terminus of the rat 5-HT(3)R, was found in >80% of duodenal vagal and spinal afferents. These results show that duodenal extrinsic afferents express 5-HT(3)R and that the receptor mediates specific glucose-induced inhibition of gastric emptying. These findings support the hypothesis that enterochromaffin cells in the intestinal mucosa release 5-HT in response to glucose, which activates 5-HT(3)R on afferent nerve terminals to evoke reflex changes in gastric motility. The primary glucose sensors of the intestine may be mucosal enterochromaffin cells.

  5. Safety of serotonin (5-HT3) receptor antagonists in patients undergoing surgery and chemotherapy: protocol for a systematic review and network meta-analysis

    PubMed Central

    2013-01-01

    Background Serotonin (5-HT3) receptor antagonists are a class of antiemetic medications often used to prevent nausea and vomiting among patients undergoing chemotherapy, radiotherapy or surgery. However, recent studies suggest that these agents might be associated with increased cardiac harm. To examine this further, we are proposing to conduct a systematic review and network meta-analysis on the comparative safety of 5-HT3 receptor antagonists among patients undergoing chemotherapy or surgery. Methods/Design Studies reporting one or more safety outcomes of interest for 5-HT3 receptor antagonists compared with each other, placebo, and/or other anti-emetic agents (for example, benzamides, phenothiazines, butyrophenones, antihistamines, and anticholinergics) among children and adult patients undergoing surgery or chemotherapy will be included. Our primary outcome of interest is arrhythmia. Our secondary outcomes include cardiac death, QT prolongation, PR prolongation, all-cause mortality, nausea, and vomiting. We will include experimental studies, quasi-experimental studies (namely controlled before-after and interrupted time series), and observational studies (namely cohort studies). We will not limit inclusion by publication status, time period, duration of follow-up or language of dissemination. Electronic databases (for example, MEDLINE, EMBASE) will be searched from inception onwards. These main searches will be supplemented by searching for difficult to locate and unpublished studies, such as dissertations, and governmental reports. The eligibility criteria will be pilot-tested and subsequently used to screen the literature search results by two reviewers in duplicate. A similar process will be followed for full-text screening, data abstraction, and risk of bias/methodological quality appraisal. The Cochrane Risk of Bias tool will be used to appraise experimental and quasi-experimental studies, and cohort studies will be assessed using the Newcastle Ottawa

  6. 5HT3 receptor antagonist (ondansetron) reverses depressive behavior evoked by chronic unpredictable stress in mice: modulation of hypothalamic-pituitary-adrenocortical and brain serotonergic system.

    PubMed

    Gupta, Deepali; Radhakrishnan, Mahesh; Kurhe, Yeshwant

    2014-09-01

    Chronic stress is one of the major causes of depression, associated with behavioral and biochemical impairments. 5HT3 receptor antagonists (such as ondansetron) have shown alleviation of depressive symptomology in preclinical and in few clinical studies. However, their effects in chronic stress-induced depressive behavior and the underlying mechanism(s) are yet to be known. In the present study, the effects of a 5HT3 receptor antagonist, ondansetron were evaluated in chronic unpredictable stress (CUS)-evoked depressive behavior. In addition, the possible mechanism was determined by measuring plasma corticosterone (CORT) as a marker of hypothalamic-pituitary-adrenocortical (HPA)-axis activity and serotonin levels in the discrete brain regions. Mice were subjected to a battery of unpredictable stressors for 28 days. Ondansetron (0.05, 0.1 and 1mg/kg, p.o.) and fluoxetine (10mg/kg, p.o.) were administered during the last 14 days (day 15-28th) of CUS testing paradigm. The results showed that the 4-week CUS produced significant depressive behavior in mice, which included increased despair effects in forced swim test (FST) and reward-related deficits in sucrose preference test. Biochemical assays demonstrated a significant increase in percentage of plasma CORT and decrease in percentage of serotonin levels in the discrete brain regions of CUS mice. Chronic ondansetron treatment, similar to that of positive control fluoxetine, significantly reversed despair effects in FST and reward-related deficits in sucrose preference test. In addition, ondansetron and fluoxetine treatments significantly increased percentage of serotonin levels in the measured brain regions and attenuated HPA-axis hyperactivity, as evidenced by low percentage of plasma CORT levels in CUS mice. These findings indicate the potential role of ondansetron (a 5HT3 receptor antagonist) in reversing CUS-induced depressive behavior, which is possibly mediated by its modulating effects on the HPA-axis and

  7. Competitive interaction of agonists and antagonists with 5-HT3 recognition sites in membranes of neuroblastoma cells labelled with (/sup 3/H)ICS 205-930

    SciTech Connect

    Hoyer, D.; Neijt, H.C.; Karpf, A.

    1989-01-01

    (3H)ICS 205-930 labelled 5-HT3 recognition sites in membranes prepared from murine neuroblastoma N1E-115 cells. Binding was rapid, reversible, saturable and stereoselective to an apparently homogeneous population of sites. Kinetic studies revealed that agonists and antagonists produced a monophasic dissociation reaction of (3H)ICS 205-930 from its recognition sites. The dissociation rate constant of the radioligand was similar whether the dissociation was induced by an agonist or an antagonist. Competition studies carried out with agonists and antagonists also suggested the presence of a homogeneous population of (3H)ICS 205-930 recognition sites. Competition curves were best fit for a 1 site model. (3H)ICS 205-930 binding sites displayed the pharmacological profile of a 5-HT3 receptor. The interactions of agonists and antagonists with (3H)ICS 205-930 recognition sites were apparently competitive in nature, as demonstrated in kinetic and equilibrium experiments. In saturation experiments carried out with (3H)ICS 205-930 in the presence and the absence of unlabelled agonists and antagonists, apparent Bmax values were not reduced whereas apparent Kd values were increased in the presence of competing ligands. There was a good agreement between apparent pKB values calculated for the competing ligands in saturation experiments and pKd values calculated from competition experiments. The present data demonstrate that (3H)ICS 205-930 labels a homogeneous population of sites at which agonists and antagonists interact competitively.

  8. Differences in regional cerebral blood flow response to a 5HT3 antagonist in early- and late-onset cocaine-dependent subjects.

    PubMed

    Adinoff, Bryon; Devous, Michael D; Williams, Mark J; Harris, Thomas S; Best, Susan E; Dong, Hongyun; Zielinski, Tanya

    2014-03-01

    5-hydroxytryptamine 3 (5HT3) receptors are important modulators of mesostriatal dopaminergic transmission and have been implicated in the pathophysiology of cocaine reward, withdrawal and self-administration. In addition, the 5HT3 antagonist ondansetron is effective in treating early-onset, but not late-onset, alcohol-dependent subjects. To explore the role of 5HT3 receptor systems in cocaine addiction using functioning imaging, we administered ondansetron to 23 abstinent, treatment-seeking cocaine-addicted and 22 sex-, age- and race-matched healthy control participants. Differences between early- (first use before 20 years, n = 10) and late-onset (first use after 20 years, n = 10) cocaine-addicted subjects were also assessed. On two separate days, subjects were administered ondansetron (0.15 mg/kg intravenously over 15 minutes) or saline. Regional cerebral blood flow (rCBF) was measured following each infusion with single photon emission computed tomography. No significant rCBF differences between the cocaine-addicted and control participants were observed following ondansetron relative to saline. Early-onset subjects, however, showed increased (P < 0.001) right posterior parahippocampal rCBF following ondansetron. In contrast, late-onset subjects showed decreased rCBF following ondansetron in an overlapping region of the right parahippocampal/hippocampal gyrus. Early-onset subjects also displayed increased rCBF in the left anterior insula and subthalamic nucleus following ondansetron; late-onset subjects showed decreased rCBF in the right anterior insula. These findings suggest that the age of drug use onset is associated with serotonergic biosignatures in cocaine-addicted subjects. Further clarification of these alterations may guide targeted treatment with serotonergic medications similar to those successfully used in alcohol-dependent patients.

  9. 5-Chloroindole: a potent allosteric modulator of the 5-HT3 receptor

    PubMed Central

    Newman, Amy S; Batis, Nikolaos; Grafton, Gillian; Caputo, Francesca; Brady, Catherine A; Lambert, Jeremy J; Peters, John A; Gordon, John; Brain, Keith L; Powell, Andrew D; Barnes, Nicholas M

    2013-01-01

    Background and Purpose The 5-HT3 receptor is a ligand-gated ion channel that is modulated allosterically by various compounds including colchicine, alcohols and volatile anaesthetics. However the positive allosteric modulators (PAMs) identified to date have low affinity, which hinders investigation because of non-selective effects at pharmacologically active concentrations. The present study identifies 5-chloroindole (Cl-indole) as a potent PAM of the 5-HT3 receptor. Experimental Approach 5-HT3 receptor function was assessed by the increase in intracellular calcium and single-cell electrophysiological recordings in HEK293 cells stably expressing the h5-HT3A receptor and also the mouse native 5-HT3 receptor that increases neuronal contraction of bladder smooth muscle. Key Results Cl-indole (1–100 μM) potentiated agonist (5-HT) and particularly partial agonist [(S)-zacopride, DDP733, RR210, quipazine, dopamine, 2-methyl-5-HT, SR57227A, meta chlorophenyl biguanide] induced h5-HT3A receptor-mediated responses. This effect of Cl-indole was also apparent at the mouse native 5-HT3 receptor. Radioligand-binding studies identified that Cl-indole induced a small (∼twofold) increase in the apparent affinity of 5-HT for the h5-HT3A receptor, whereas there was no effect upon the affinity of the antagonist, tropisetron. Cl-indole was able to reactivate desensitized 5-HT3 receptors. In contrast to its effect on the 5-HT3 receptor, Cl-indole did not alter human nicotinic α7 receptor responses. Conclusions and Implications The present study identifies Cl-indole as a relatively potent and selective PAM of the 5-HT3 receptor; such compounds will aid investigation of the molecular basis for allosteric modulation of the 5-HT3 receptor and may assist the discovery of novel therapeutic drugs targeting this receptor. Linked Articles Recent reviews on allosteric modulation can be found at: Kenakin, T (2013). New concepts in pharmacological efficacy at 7TM receptors: IUPHAR Review 2

  10. Tropisetron attenuates cisplatin-induced nephrotoxicity in mice.

    PubMed

    Zirak, Mohammad Reza; Rahimian, Reza; Ghazi-Khansari, Mahmoud; Abbasi, Ata; Razmi, Ali; Mehr, Shahram Ejtemaei; Mousavizadeh, Kazem; Dehpour, Ahmad Reza

    2014-09-05

    Nephrotoxicity is one of the most important complications of cisplatin, a potent chemotherapeutic agent used in the treatment of various malignancies. 5-HT3 antagonists are widely used to counteract chemotherapy-induced emesis and new studies reveal that they poses notable anti-inflammatory properties. In current study, we investigated the effects of 5-HT3 antagonists on cisplatin induced nephrotoxicity in mice. To identify the underlying mechanism of renal protection by tropisetron, we investigated the probable involvement of alpha7 nicotinic acetylcholine receptor (α7nAChR). A single injection of cisplatin (20mg/kg; i.p) induced nephrotoxicity, 5-HT3 antagonists (tropisetron, granisetron and ondansetron,) were given twice daily for 3 day (3mg/kg; i.p). Finally animals were euthanized and blood sample was collected to measure urea and creatinin level. Also kidneys were removed for histopathological examination and biochemical measurements including glutathione (GSH), malondialdehyde (MDA), superoxide dismutase (SOD) activity, inducible nitric oxide synthase (iNOS) expression and inflammatory cytokines. Tropisetron decreased the expression of inflammatory molecules including tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and iNOS and improved histopathological damage and renal dysfunction. However other 5-HT3 antagonists, granisetron or ondansetron do not have any elicit effects on biochemical markers and histological damages. Since methyllycaconitine, antagonist of α7nAChR, was unable to reverse the beneficial effect of tropisetron, we concluded that this effect of tropisetron is not mediated by α7nAChR.Our results showed that tropisetron treatment markedly ameliorated the experimental cisplatin induced-nephrotoxicity and this effect might be 5-HT3 receptor and α7nAChR independent.

  11. Palonosetron versus other 5-HT(3) receptor antagonists for prevention of chemotherapy-induced nausea and vomiting in patients with cancer on chemotherapy in a hospital outpatient setting.

    PubMed

    Balu, Sanjeev; Buchner, Deborah; Craver, Chris; Gayle, Julie

    2011-04-01

    Despite favorable evidence from clinical trials for single-dose palonosetron versus other commercially available 5-HT(3)-receptor antagonists for the prophylaxis of chemotherapy-induced nausea and vomiting (CINV), clinical comparative data are scarce from hospital outpatient settings, where these antiemetic agents are used in patients diagnosed with cancer who are receiving chemotherapy (CTH). The purpose of our retrospective study was to assess the hospital claims to evaluate the rate of uncontrolled CINV with antiemetic prophylaxis using palonosetron versus other 5-HT(3)-receptor antagonists in patients diagnosed with cancer who are receiving CTH (highly emetogenic CTH, moderately emetogenic CTH, low-emetogenic CTH, or minimally emetogenic CTH) treatment in a hospital outpatient setting. Patients aged ≥18 years who had cancer and were being treated with CTH and antiemetic prophylaxis with palonosetron (Group 1) and other 5-HT(3) receptor antagonists (Group 2) for the first time between April 1, 2007, and March 31, 2009, were identified using a hospital-service database. Within each CTH cycle, CINV events were identified through International Classification of Diseases (ICD)-9 codes for nausea, vomiting, and/or volume depletion (from Day 1 of each CTH administration until the end of the CTH cycle) or for use of rescue medications (Day 2 until the end of the CTH cycle). A multivariate regression model was developed to predict uncontrolled CINV event rates per CTH cycle between Groups 1 and 2 matched on CTH emetogenicity distribution in the study follow-up period (first of 8 cycles or 6 months). A subgroup analysis of patients on CTH with the highest risk of nausea and vomiting (highly emetogenic CTH or moderately emetogenic CTH) was also conducted. Of 9144 identified patients, 1775 were prescribed palonosetron (Group 1). Group 1 patients were statistically younger (61.2 vs 62.8 years; P < 0.001), composed of more females (57.1% vs 51.9%; P < 0.001) and more

  12. Anti-depressant-like activity of a novel serotonin type-3 (5-HT3) receptor antagonist in rodent models of depression.

    PubMed

    Gupta, Deepali; Devadoss, Thangaraj; Bhatt, Shvetank; Gautam, Baldev; Jindal, Ankur; Pandey, Dilip; Mahesh, Radhakrishnan

    2011-08-01

    N-Cyclohexyl-3-methoxyquinoxalin-2-carboxamide (QCM-13), a novel 5-HT3 antagonist identified from a series of compounds with higher pA2 (7.6) and good log P (2.91) value was screened in rodent models of depression such as forced swim test (FST), tail suspension test (TST), interaction studies with standard anti-depressants and confirmatory studies such as reversal of parthenolide induced depression and reserpine induced hypothermia. In FST (2 and 4 mg/kg) and TST (2 and 4 mg/kg), QCM-13 significantly reduced the duration of immobility in mice without affecting the base line locomotion. QCM-13 (2 and 4 mg/kg) was also found to have significant interaction with standard anti-depressants (fluoxetine and bupropion in FST and TST respectively). Further, reversal of parthenolide induced depression in mice and reserpine induced hypothermia in rat models indicate the serotonergic influence of QCM-13 for anti-depressant potential.

  13. X-ray analysis of the effect of the 5-HT3 receptor antagonist granisetron on gastrointestinal motility in rats repeatedly treated with the antitumoral drug cisplatin.

    PubMed

    Vera, Gema; López-Pérez, Ana Esther; Martínez-Villaluenga, María; Cabezos, Pablo Antonio; Abalo, Raquel

    2014-08-01

    Cancer chemotherapy is associated with the development of numerous adverse effects, including nausea, emesis and other alterations in gastrointestinal (GI) motility. The administration of 5-HT3 receptor antagonists has provided a clinical advance in the treatment of chemotherapy-induced vomiting but these drugs lose efficacy throughout chronic treatment. The effects of these drugs in experimental animals under chronic administration are not well known. Our aim was to study, using radiographic methods, the effect of the 5-HT3 receptor antagonist granisetron on GI dysmotility induced in the rat by repeated cisplatin administration. First, invasive methods were used to select a dose of granisetron capable of reducing increased stomach weight due to acute cisplatin administration (6 mg/kg, ip). Second, rats received two intraperitoneal (ip) injections once a week for 4 weeks: granisetron (1 mg/kg, ip) or saline and, thirty min later, saline or cisplatin (2 mg/kg, ip). Body weight gain was measured throughout treatment. Radiological techniques were used to determine the acute (after first dose) and chronic (after last dose) effects of cisplatin and/or granisetron on GI motility. Repeated cisplatin-induced weight loss which granisetron did not prevent. Gastric emptying was delayed after the first cisplatin administration. Granisetron completely prevented this effect. After weekly administration, cisplatin-induced gastric dysmotility was enhanced and granisetron was not capable of completely preventing this effect. Granisetron prevents gastric emptying alterations, but its efficacy decreases throughout antineoplastic treatment. This might be due to the enhanced effect of cisplatin.

  14. Effects of 5-HT3 Antagonists on Symptom Relief and Constipation in Non-constipated Irritable Bowel Syndrome: A Systematic Review and Meta-analysis of Randomized Controlled Trials

    PubMed Central

    Andresen, Viola; Montori, Victor M.; Keller, Jutta; West, Colin P.; Layer, Peter; Camilleri, Michael

    2008-01-01

    Background & Aims We performed a systematic review and meta-analyses to estimate treatment efficacy and constipation rate of 5-HT3 antagonists in patients with non-constipated (NC) or diarrhea-predominant (D) -IBS. Methods Two reviewers independently searched MEDLINE, EMBASE, and Web of Science (1966 to December 15th 2006) for randomized controlled trials (RCTs) of 5-HT3 antagonists in IBS reporting clinical endpoints of the IBS symptom complex and safety parameters. Study characteristics, markers of methodological quality, and outcomes for the intention-to-treat population for each RCT were extracted independently. Results We found 14 eligible RCTs of alosetron (n=3024) or cilansetron (n=1116) vs. placebo (n=3043) or mebeverine (n=304). Random effects meta-analyses found 5-HT3 antagonists more effective than the comparators in achieving global improvement in IBS symptoms (pooled relative risk 1.60, 95% CI 1.49, 1.72; I2=0%) and relief of abdominal pain and discomfort (pooled relative risk 1.30, 95% CI 1.22, 1.39, I2=22%). Benefit was apparent for both agents, in patients of either sex. These agents were more likely to cause constipation (pooled relative risk 4.28, 95% CI 3.28, 5.60, I2=65%); there was less constipation with 5-HT3 antagonists in D-IBS patients than in mixed populations (NC- and D-IBS; ratio of RR 0.65, 95% CI 0.41, 0.99). Nine patients (0.2%) using 5-HT3 antagonists had, at least, possible ischemic colitis versus none in control groups. Conclusions 5-HT3 antagonists significantly improve symptoms of NC- or D-IBS in men and women. There is increased risk of constipation with 5-HT3 antagonists, although the risk is lower in those with D-IBS. PMID:18242143

  15. Effect of R3487/MEM3454, a novel nicotinic alpha7 receptor partial agonist and 5-HT3 antagonist on sustained attention in rats.

    PubMed

    Rezvani, Amir H; Kholdebarin, Ehsan; Brucato, Frederic H; Callahan, Patrick M; Lowe, David A; Levin, Edward D

    2009-03-17

    It is well established that nicotinic systems in the brain are critically involved in attentional processes in both animals and humans. The current study assessed the effects of a novel nicotinic alpha7 receptor partial agonist and 5-HT3 antagonist, R3487/MEM3454 (also referred to as R3487 or MEM 3454) on sustained attention in rats performing an operant visual signal detection task. The effects of R3487/MEM3454 were compared to those of the acetylcholinesterase inhibitor/nicotinic alpha7 allosteric positive modulator galanthamine. Adult female Sprague-Dawley rats were injected subcutaneously with R3487/MEM3454 (0.03, 0.1, 0.15, 0.3 and 0.6 mg/kg), galanthamine (0.25, 0.5, 1, 2 mg/kg) or vehicle 30 min before the attentional test. In the second study, the time-dependent effects of R3487/MEM3454 were assessed by injecting the compound (0.6 mg/kg, s.c.) at different pretreatment intervals (30, 60 or 90 min) before the start of the attentional task. Our results show a significant dose-effect for R3487/MEM3454 on percent hit accuracy performance without any significant alteration on percent correct rejection performance. In the time-dependent test, R3487/MEM3454 significantly increased the percent hit accuracy performance when animals were injected 60 min before the start of the attentional task. Administration of galanthamine failed to significantly increase percent hit accuracy performance and increasing the dose of galanthamine produced a decrease in percent correct rejection performance. The present findings with R3487/MEM3454 suggest that nicotinic alpha7 receptors and/or 5-HT3 receptors may play an important role in modulating sustained attention and that R3487/MEM3454 may have therapeutic potential in improving sustained attention in humans.

  16. Effect of a novel 5-HT3 receptor antagonist 4i, in corticosterone-induced depression-like behavior and oxidative stress in mice.

    PubMed

    Gupta, Deepali; Radhakrishnan, Mahesh; Kurhe, Yeshwant

    2015-04-01

    Stress in our daily life severely affects the normal physiology of the biological system. Dysregulation of hypothalamic-pituitary-adrenal (HPA) axis has been implicated in the development of depression-like behavior, which remains under diagnosed and poorly treated. Exogenous corticosterone (CORT) administration has been demonstrated to develop a depression model, which has shown to mimic HPA-axis induced depression-like state in rodents. In the present study, the effect of a novel 5HT3 receptor, 4i was examined on CORT induced depression in mice. CORT (30mg/kg, subcutaneously) was given for 4-weeks to mice in control group, while mice in drug treated group were given 4i (0.5-1mg/kg, intraperitoneally)/fluoxetine (as a positive control, 10mg/kg), for the last 2-weeks of CORT dosing. Repeated CORT dosing caused depression-like behavior in mice as indicated by increased despair effects in forced swim test (FST) and anhedonia in sucrose preference test. In addition, CORT administration induced oxidative load in the brain with significant increase in pro-oxidant (lipid peroxidation and nitrite levels) markers and a substantial decline in anti-oxidant defense (catalase and reduced glutathione levels) system, indicating a direct effect of stress hormones in the induction of the brain oxidative damage. On the other hand, 4i and fluoxetine treatment reversed the CORT induced depressive-like deficits. Furthermore, 4i and fluoxetine prevented CORT induced oxidative brain insults, which may plausibly demonstrate one of the key mechanisms for antidepressant-like effects of the compounds. Thus, the study suggests that 5HT3 antagonist; 4i may be implicated as pharmacological intervention targeting depressive-like anomaly associated with HPA-axis dysregulation.

  17. Palonosetron-5-HT3 Receptor Interactions As Shown by a Binding Protein Cocrystal Structure.

    PubMed

    Price, Kerry L; Lillestol, Reidun K; Ulens, Chris; Lummis, Sarah C R

    2016-12-21

    Palonosetron is a potent 5-HT3 receptor antagonist and an effective therapeutic agent against emesis. Here we identify the molecular determinants of compound recognition in the receptor binding site by obtaining a high resolution structure of palonosetron bound to an engineered acetylcholine binding protein that mimics the 5-HT3 receptor binding site, termed 5-HTBP, and by examining the potency of palonosetron in a range of 5-HT3 receptors with mutated binding site residues. The structural data indicate that palonosetron forms a tight and effective wedge in the binding pocket, made possible by its rigid tricyclic ring structure and its interactions with binding site residues; it adopts a binding pose that is distinct from the related antiemetics granisetron and tropisetron. The functional data show many residues previously shown to interact with agonists and antagonists in the binding site are important for palonosetron binding, and indicate those of particular importance are W183 (a cation-π interaction and a hydrogen bond) and Y153 (a hydrogen bond). This information, and the availability of the structure of palonosetron bound to 5-HTBP, should aid the development of novel and more efficacious drugs that act via 5-HT3 receptors.

  18. Broad-spectrum antiemetic potential of the L-type calcium channel antagonist nifedipine and evidence for its additive antiemetic interaction with the 5-HT(3) receptor antagonist palonosetron in the least shrew (Cryptotis parva).

    PubMed

    Darmani, Nissar A; Zhong, Weixia; Chebolu, Seetha; Vaezi, Mariam; Alkam, Tursun

    2014-01-05

    Cisplatin-like chemotherapeutics cause vomiting via release of multiple neurotransmitters (dopamine, serotonin (5-HT), or substance P (SP)) from the gastrointestinal enterochromaffin cells and/or the brainstem via a calcium dependent process. Diverse channels in the plasma membrane allow extracellular Ca(2+) entry into cells for the transmitter release process. Agonists of 5-HT3 receptors increase calcium influx through both 5-HT3 receptors and L-type Ca(2+) channels. We envisaged that L-type calcium agonists such as FPL 64176 should cause vomiting and corresponding antagonists such as nifedipine would behave as broad-spectrum antiemetics. Administration of FPL 64176 did cause vomiting in the least shrew in a dose-dependent fashion. Nifedipine and the 5-HT3 receptor antagonist palonosetron, potently suppressed FPL 64176-induced vomiting, while a combination of ineffective doses of these antagonists was more efficacious. Subsequently, we investigated the broad-spectrum antiemetic potential of nifedipine against diverse emetogens including agonists of serotonergic 5-HT3- (e.g. 5-HT or 2-Me-5-HT), SP tachykinin NK1- (GR73632), dopamine D2- (apomorphine or quinpirole), and cholinergic M1- (McN-A-343) receptors, as well as the non-specific emetogen, cisplatin. Nifedipine by itself suppressed vomiting in a potent and dose-dependent manner caused by the above emetogens except cisplatin. Moreover, low doses of nifedipine potentiated the antiemetic efficacy of non-effective or semi-effective doses of palonosetron against vomiting caused by either 2-Me-5-HT or cisplatin. Thus, our findings demonstrate that activation of L-type calcium channels causes vomiting, whereas blockade of these ion channels by nifedipine-like antagonists not only provides broad-spectrum antiemetic activity but can also potentiate the antiemetic efficacy of well-established antiemetics such as palonosetron. L-type calcium channel antagonists should also provide antiemetic activity against drug

  19. The interaction of trichloroethanol with murine recombinant 5-HT3 receptors.

    PubMed Central

    Downie, D L; Hope, A G; Belelli, D; Lambert, J J; Peters, J A; Bentley, K R; Steward, L J; Chen, C Y; Barnes, N M

    1995-01-01

    108-15 cells or HEK 293 cells. Similarly, competition for [3H]-granisetron binding by the 5-HT3 receptor antagonists ondansetron and tropisetron was unaffected. However, competition for [3H]-granisetron binding by the 5-HT3 receptor agonists, 5-HT, 2-methyl-5-HT and phenylbiguanide was enhanced by trichloroethanol (2.5 mM).(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7541281

  20. Antidepressant-like effect of novel 5-HT3 receptor antagonist N-n-butyl-3-ethoxyquinoxalin-2-carboxamide (6p): an approach using rodent behavioral antidepressant tests.

    PubMed

    Bhatt, Shvetank; Mahesh, Radhakrishnan; Devadoss, Thangaraj; Jindal, Ankur Kumar

    2013-01-01

    The present study was designed to investigate the antidepressant potential of N-n-butyl-3-ethoxyquinoxalin-2-carboxamide (6p), a novel 5-HT3 receptor antagonist in rodent behavioral models of depression. The compound 6p was examined in various behavioral models like forced swim test (FST), tail suspension test (TST), mechanistic models [5-hydroxytryptophan (5-HTP)-induced head twitch and reserpine-induced hypothermia (RIH)], and in chronic surgery model-olfactory bulbectomy in rats. Compound 6p (1, 2, and 4 mg/kg, i.p.) exhibited antidepressant-like effect in FST and TST after acute treatment without having an effect on baseline locomotor activity. Moreover, 6p (2 mg/kg, i.p.), potentiated the 5-HTP-induced head twitch responses in mice and inhibited the RIH in rats. Chronic treatment (14 days) with 6p (1 and 2 mg/kg, p.o.) and paroxetine (10 mg/kg, p.o.) in rats significantly reversed the behavioral anomalies induced by bilateral olfactory bulbectomy using open field exploration. The preliminary studies reveal that compound 6p exhibits antidepressant-like effect in behavioral rodent models of depression.

  1. Antidepressant and anxiolytic-like effects of 4n, a novel 5-HT3 receptor antagonist using behaviour based rodent models.

    PubMed

    Kumar, Baldev; Jindal, Ankur; Pandey, Dilip Kumar; Bhatt, Shvetank; Devadoss, Thangaraj; Mahesh, Radhakrishnan

    2012-09-01

    The present study was designed to investigate the putative antidepressant and anxiolytic-like effects of N-n-Butylquinoxalin-2-carboxamide (4n), a novel 5-HT3 receptor antagonist, with an optimal log P (2.01) and pA2 value (7.3) greater than ondansetron (6.9) using rodent behavioural models of depression and anxiety. Acute treatment of 4n (1-4 mg/kg, ip) in mice produced antidepressant-like effect in forced swim test (FST) without affecting the baseline locomotion in actophotometer test in mice. 4n (2-4 mg/kg, ip) treatment also potentiated the 5-hydroxytryptophan (5-HTP) induced head twitch response in mice. Further, 4n (1-4 mg/kg, ip) treatment antagonized reserpine induced hypothermia in rats. Chronic treatment (14 days) with 4n (1-4 mg/kg) and paroxetine (10 mg/kg) significantly attenuated the behavioural anomalies induced by bilateral olfactory bulbectomy in rats in modified open field paradigm. An anxiogenic-like behaviour was induced by light alone as the stimulus using light-dark aversion test. 4n (2-4 mg/kg, ip) treatment significantly increased no. of transitions between dark and lit area and the time spent in the lit area. In conclusion, these preliminary investigations confirm that 4n exhibited antidepressant and anxiolytic-like effects in rodent models of depression and anxiety.

  2. Antidepressant-like effect of novel 5-HT3 receptor antagonist N-n-butyl-3-ethoxyquinoxalin-2-carboxamide (6p): An approach using rodent behavioral antidepressant tests

    PubMed Central

    Bhatt, Shvetank; Mahesh, Radhakrishnan; Devadoss, Thangaraj; Jindal, Ankur Kumar

    2013-01-01

    Objective: The present study was designed to investigate the antidepressant potential of N-n-butyl-3-ethoxyquinoxalin-2-carboxamide (6p), a novel 5-HT3 receptor antagonist in rodent behavioral models of depression. Materials and Methods: The compound 6p was examined in various behavioral models like forced swim test (FST), tail suspension test (TST), mechanistic models [5-hydroxytryptophan (5-HTP)-induced head twitch and reserpine-induced hypothermia (RIH)], and in chronic surgery model-olfactory bulbectomy in rats. Results: Compound 6p (1, 2, and 4 mg/kg, i.p.) exhibited antidepressant-like effect in FST and TST after acute treatment without having an effect on baseline locomotor activity. Moreover, 6p (2 mg/kg, i.p.), potentiated the 5-HTP–induced head twitch responses in mice and inhibited the RIH in rats. Chronic treatment (14 days) with 6p (1 and 2 mg/kg, p.o.) and paroxetine (10 mg/kg, p.o.) in rats significantly reversed the behavioral anomalies induced by bilateral olfactory bulbectomy using open field exploration. Conclusion: The preliminary studies reveal that compound 6p exhibits antidepressant-like effect in behavioral rodent models of depression. PMID:24014909

  3. Effects of serotonin 5-HT3 receptor antagonists on stress-induced colonic hyperalgesia and diarrhoea in rats: a comparative study with opioid receptor agonists, a muscarinic receptor antagonist and a synthetic polymer.

    PubMed

    Hirata, T; Keto, Y; Nakata, M; Takeuchi, A; Funatsu, T; Akuzawa, S; Sasamata, M; Miyata, K

    2008-05-01

    In this study, we examined the effects of serotonin (5-HT)3 receptor antagonists (5-HT3RAs) including ramosetron, alosetron, and cilansetron on colonic nociceptive threshold in rats. Furthermore, we established a restraint stress-induced colonic hyperalgesia model in rats, and compared the inhibitory effects of 5-HT3RAs on restraint stress-induced colonic hyperalgesia and diarrhoea with those of loperamide, trimebutine, tiquizium and polycarbophil. The colonic nociceptive threshold was measured as the balloon pressure at the time the rat showed a nociceptive response during colonic distension by an intrarectally inserted balloon. Oral administration of ramosetron (3-30 microg kg(-1)), alosetron (30-300 microg kg(-1)), or cilansetron (30-300 microg kg(-1)) increased the colonic nociceptive threshold in a dose-dependent manner in non-stressed rats. Restraint stress for 1 h significantly decreased the colonic nociceptive threshold, but ramosetron (0.3-3 microg kg(-1)), alosetron (3-30 microg kg(-1)), cilansetron (3-30 microg kg(-1)) and trimebutine (100-1000 mg kg(-1)) significantly inhibited the decrease in the threshold. Loperamide (3-30 mg kg(-1)), tiquizium (100-1000 mg kg(-1)) and polycarbophil (1000 mg kg(-1)) did not affect the restraint stress-induced decrease in the colonic nociceptive threshold. All drugs tested in this study showed dose-dependent inhibition of restraint stress-induced diarrhoea in rats. These results indicate that, unlike existing antidiarrhoeal and spasmolytic agents, 5-HT3RAs have inhibitory effects on colonic nociception, and prevented restraint stress-induced both diarrhoea and hyperalgesia at almost the same doses in rats. This suggests that the 5-HT3RAs may be useful in ameliorating both colonic hyperalgesia and diarrhoea in patients with irritable bowel syndrome.

  4. Influence of Polymorphisms in the HTR3A and HTR3B Genes on Experimental Pain and the Effect of the 5-HT3 Antagonist Granisetron

    PubMed Central

    Hedenberg-Magnusson, Britt; List, Thomas; Svensson, Peter; Schalling, Martin

    2016-01-01

    The aim of this study was to investigate experimentally if 5-HT3 single nucleotide polymorphisms (SNP) contribute to pain perception and efficacy of the 5-HT3-antagonist granisetron and sex differences. Sixty healthy participants were genotyped regarding HTR3A (rs1062613) and HTR3B (rs1176744). First, pain was induced by bilateral hypertonic saline injections (HS, 5.5%, 0.2 mL) into the masseter muscles. Thirty min later the masseter muscle on one side was pretreated with 0.5 mL granisetron (1 mg/mL) and on the other side with 0.5 mL placebo (isotonic saline) followed by another HS injection (0.2 mL). Pain intensity, pain duration, pain area and pressure pain thresholds (PPTs) were assessed after each injection. HS evoked moderate pain, with higher intensity in the women (P = 0.023), but had no effect on PPTs. None of the SNPs influenced any pain variable in general, but compared to men, the pain area was larger in women carrying the C/C (HTR3A) (P = 0.015) and pain intensity higher in women with the A/C alleles (HTR3B) (P = 0.019). Pre-treatment with granisetron reduced pain intensity, duration and area to a lesser degree in women (P < 0.05), but the SNPs did not in general influence the efficacy of granisetron. Women carrying the C/T & T/T (HTR3A) genotype had less reduction of pain intensity (P = 0.041) and area (P = 0.005), and women with the C/C genotype (HTR3B) had less reduction of pain intensity (P = 0.030), duration (P = 0.030) and area compared to men (P = 0.017). In conclusion, SNPs did not influence experimental muscle pain or the effect of granisetron on pain variables in general, but there were some sex differences in pain variables that seem to be influenced by genotypes. However, due to the small sample size further research is needed before any firm conclusions can be drawn. PMID:28002447

  5. Antidepressant and anti-anxiety like effects of 4i (N-(3-chloro-2-methylphenyl) quinoxalin-2-carboxamide), a novel 5-HT3 receptor antagonist in acute and chronic neurobehavioral rodent models.

    PubMed

    Gupta, Deepali; Radhakrishnan, Mahesh; Thangaraj, Devadoss; Kurhe, Yeshwant

    2014-07-15

    Depression and anxiety are the most debilitating mood disorders with poor therapeutic recovery rates. In the last decades, 5-HT3 receptor antagonists have been identified as potential agents for mood disorders. The current investigation focuses on evaluating the, antidepressant and anti-anxiety like effects of a novel 5-HT3 antagonist, 4i (N-(3-chloro-2-methylphenyl) quinoxalin-2-carboxamide). Preliminary, in vitro 5-HT3 receptor binding affinity was performed in isolated longitudinal muscle-myenteric plexus from the guinea pig ileum. Consequently, neurobehavioral effects of 4i in acute and chronic rodent models were evaluated. In addition, involvement of serotonergic system in the postulated effects of the compound was analyzed by in vivo assay. in vitro, 4i demonstrated high 5-HT3 receptor antagonistic activity (pA2, 7.6). in vivo acute study, 4i exhibited decreased duration of immobility in forced swim and tail suspension tests, and increased exploratory parameters as number and duration of nose-poking in hole board test and latency and time spent in aversive brightly illuminated light chamber in light-dark model. Moreover, in chronic model of depression, i.e., olfactory bulbectomy with behavioral deficits, 4i reversed depressive anhedonia in sucrose preference test and anxious hyperactive behavior in open field test in rats. Furthermore, synergistic effect of 4i with fluoxetine (a selective serotonin reuptake inhibitor) and inhibitory effect of 1-(m-chlorophenyl)-biguanide (a 5-HT3 receptor agonist) revealed serotonergic modulation by 4i mediated 5-HT3 receptor antagonism, which was further confirmed by potentiation of 5-hydroxytryptophan (a serotonin synthesis precursor) induced head twitch response. These findings suggest the potential antidepressant and anti-anxiety like effects of 4i, which may be related to the modulation of serotonergic system. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Ondansetron, a 5HT3 receptor antagonist reverses depression and anxiety-like behavior in streptozotocin-induced diabetic mice: possible implication of serotonergic system.

    PubMed

    Gupta, Deepali; Radhakrishnan, Mahesh; Kurhe, Yeshwant

    2014-12-05

    Increased prevalence and high comorbidity of depression-like mood disorders and diabetes have prompted investigation of new targets and potential contributing agents. There is considerable evidence supporting the inconsistent clinical efficacy and persistent undesirable effects of existing antidepressant therapy for depression associated with diabetes. Therefore, the present study was aimed at investigating the effect of ondansetron, a selective 5HT3 receptor antagonist in attenuating depression and anxiety-like behavior comorbid with diabetes. Experimentally, Swiss albino mice were rendered diabetic by a single intraperitoneal (i.p.) injection of streptozotocin (STZ, 200 mg/kg). After 8 weeks, diabetic mice received a single dose of vehicle/ondansetron (0.5 and 1 mg/kg, p.o.)/fluoxetine (the positive control, 10 mg/kg p.o.) for 28 days. Thereafter, behavioral studies were conducted to test depression-like behavior using forced swim test (FST) and anxiety-like deficits using hole-board and light-dark tests, followed by biochemical estimation of serotonin content in discrete brain regions. The results demonstrated that, STZ-induced diabetic mice exhibited increased duration of immobility and decreased swimming behavior in FST, reduced exploratory behavior during hole-board test and increased aversion to brightly illuminated light area in light-dark test as compared to non-diabetic mice, while ondansetron (similar to fluoxetine) treatment significantly reversed the same. Biochemical assay revealed that ondansetron administration attenuated diabetes-induced neurochemical impairment of serotonin function, indicated by elevated serotonin levels in discrete brain regions of diabetic mice. Collectively, the data indicate that ondansetron may reverse depression and anxiety-like behavioral deficits associated with diabetes in mice and modulation of serotonergic activity may be a key mechanism of the compound.

  7. Evidence for an extra-abdominal site of action for the 5-HT3 receptor antagonist BRL24924 in the inhibition of radiation-evoked emesis in the ferret.

    PubMed

    Andrews, P L; Hawthorn, J

    1987-09-01

    Recent studies have implicated 5-HT3(5-HT-M) receptors in the genesis of retching and vomiting evoked by antineoplastic agents. Such receptors have so far only been located peripherally, notably on the vagus. Therefore, the effects of bilateral abdominal vagotomy and antagonism of 5-HT3 receptors have been investigated on retching and vomiting induced by radiation. The gastrokinetic substituted benzamide BRL24924, (Beecham Pharmaceuticals) which has 5-HT3 receptor antagonist properties, was used. Using the ferret, it was shown that whole body x-radiation produced retching and vomiting, which was most severe during the 30 min following irradiation, and continued for at least 90 min. Abdominal vagotomy almost totally abolished the retching and vomiting, occurring during the 30 min immediately after irradiation. The following 60 min period was similar to that of control animals. This would suggest that the emetic events can be divided into a vagally-dependent and independent phase. In a small dose, BRL 24924 mimicked abdominal vagtotomy, in a larger dose, it almost totally abolished the retching and vomiting throughout the entire 90 min period. These results suggest that 5-HT3 receptor antagonists are capable of ameliorating radiation-induced retching and vomiting and that, while an important site of their action could be the abdominal vagi, other areas are probably also involved.

  8. Role of 5-HT3 Receptors in the Antidepressant Response

    PubMed Central

    Bétry, Cécile; Etiévant, Adeline; Oosterhof, Chris; Ebert, Bjarke; Sanchez, Connie; Haddjeri, Nasser

    2011-01-01

    Serotonin (5-HT)3 receptors are the only ligand-gated ion channel of the 5-HT receptors family. They are present both in the peripheral and central nervous system and are localized in several areas involved in mood regulation (e.g., hippocampus or prefrontal cortex). Moreover, they are involved in regulation of neurotransmitter systems implicated in the pathophysiology of major depression (e.g., dopamine or GABA). Clinical and preclinical studies have suggested that 5-HT3 receptors may be a relevant target in the treatment of affective disorders. 5-HT3 receptor agonists seem to counteract the effects of antidepressants in non-clinical models, whereas 5-HT3 receptor antagonists, such as ondansetron, present antidepressant-like activities. In addition, several antidepressants, such as mirtazapine, also target 5-HT3 receptors. In this review, we will report major advances in the research of 5-HT3 receptor's roles in neuropsychiatric disorders, with special emphasis on mood and anxiety disorders.

  9. Does a single intravenous injection of the 5HT3 receptor antagonist ondansetron have an analgesic effect in neuropathic pain? A double-blinded, placebo-controlled cross-over study.

    PubMed

    McCleane, Gary J; Suzuki, Rie; Dickenson, Anthony H

    2003-11-01

    Neurokinin-1-expressing neurones in lamina I to III of the spinal cord are intimately involved in the regulation of ascending and spino-bulbal pathways that regulate excitatory transmission. In experimental animals, ablation of these neurones reduces the responses to a variety of nociceptive stimuli. Furthermore, in animals, spinal application of the selective 5HT3 receptor antagonist ondansetron mimics these effects, indicating that 5HT3 receptors play a pronociceptive role and mediate descending excitatory controls that allow spinal neurones to fully code peripheral stimuli. In this study, we examined the potential analgesic effect of a single IV injection of ondansetron in humans with chronic neuropathic pain. Each consenting subject received a single IV injection of 8 mg ondansetron and placebo in varying order at least 1 wk apart with pain scores being recorded for the 48 h preceding and after each injection. Pain scores were significantly reduced 2 h after ondansetron injection (but at no other time point). This suggests that ondansetron can have an analgesic effect in neuropathic pain. Side effects were minor and infrequent. The selective 5HT3 receptor antagonist ondansetron, currently used as an antiemetic, may also have analgesic properties. Side effects with a single IV injection are infrequent and usually mild.

  10. The neuroprotective effect of tropisetron on vincristine-induced neurotoxicity.

    PubMed

    Barzegar-Fallah, Anita; Alimoradi, Houman; Mehrzadi, Saeed; Barzegar-Fallah, Niloofar; Zendedel, Adib; Abbasi, Ata; Dehpour, Ahmad Reza

    2014-03-01

    Vincristine (VCR) peripheral neuropathy is a dose-limiting side effect. Several studies have shown that tropisetron, a 5-HT3 receptor antagonist, exerts anti-inflammatory and immunomodulatory properties. Current study was designed to investigate a suppressive effect of tropisetron on VCR-induced neuropathy and whether this effect exerts through the 5-HT3 receptor or not. Neuropathy was induced in rats by administration of vincristine (0.5mg/kg, 3 intraperitoneal injections on alternate days) and in treatment group, tropisetron (3mg/kg); m-chlorophenylbiguanide (mCPBG), a selective 5-HT3 receptor agonist (15mg/kg); tropisetron (3mg/kg) plus mCPBG (15mg/kg); granisetron, another selective 5-HT3 receptor antagonist (3mg/kg) were administered intraperitoneally 1h prior to vincristine injection. Hot plate, open field tests (total distance moved, mean velocity and percentage of total duration of the movement) and motor nerve conduction velocity (MNCV) were performed to evaluate the sensory and motor neuropathy. Further, plasma levels of tumor necrosis factor-alpha (TNF-α) and interleukin-2 (IL-2) and the level of TNF-α in sciatic nerve were assessed as well as histological examination. In only VCR-treated rats hot plate latencies were significantly increased, total distance moved, mean velocity, total duration of the movement and sciatic MNCV significantly decreased compared with control. In tropisetron and tropisetron plus mCPBG groups, one injection of tropisetron prior to each VCR injection robustly diminished TNF-α and IL-2 levels, and also prevented mixed sensory-motor neuropathy, as indicated by less mortality rate, better general conditions, behavioral and electrophysiological studies. Moreover, pathological evidence confirmed the results obtained from other findings. But granisetron and mCPBG had no significant effect on the mentioned parameters. In conclusion, these studies demonstrate that tropisetron significantly suppressed VCR-induced neuropathy and could

  11. Effect of acute and chronic treatment with QCF-3 (4-benzylpiperazin-1-yl) (quinoxalin-2-yl) methanone, a novel 5-HT(3) receptor antagonist, in animal models of depression.

    PubMed

    Devadoss, Thangaraj; Pandey, Dilip K; Mahesh, Radhakrishnan; Yadav, Shushil K

    2010-01-01

    The serotonin type 3 (5-HT(3)) receptor is unique among the seven recognized serotonin receptor "families". The existence serotonin type 3 receptor (5-HT(3)) in neuro-anatomical regions stimulated the research interest for novel therapeutic targets such as anxiety, depression, nociception and cognitive function. In the current study, (4-benzylpiperazin-1-yl) (quinoxalin-2-yl) methanone (QCF-3), a novel 5-HT(3) receptor antagonist, with an optimal log P (the logarithm of the ratio of the concentrations of the un-ionized solute in the solvents is called log P) and significant pA2 value (is a negative logarithm of the molar concentration of antagonist required to reduce the effect of multiple dose agonist to that of single dose) was screened for its anti-depressant potential using rodent behavioral models of depression. Psycho-pharmacological investigations involved acute and chronic treatment (14 days) with QCF-3 and assessment of behavior during the forced swim test (FST) and tail suspension test (TST) in mice and olfactory bulbectomised rats. A dose response study in mice revealed an initial anti-depressant-like effect of QCF-3 (0.5-4 mg/kg, ip) in the FST and TST. Interaction studies showed that QCF-3 (1 and 2 mg/kg) significantly enhanced the antidepressant action of fluoxetine and bupropion in the FST and TST, respectively. QCF-3 (1 and 2 mg/kg) potentiated the 5-hydroxytryptophan (5-HTP) induced head twitches response in mice and reversed reserpine-induced hypothermia in rats. Further, OBX rats exhibited behavioral anomalies in the open field and hyper-emotionality tests that were attenuated by chronic QCF-3 treatment. In conclusion, this behavioral study describes an antidepressant-like effect of QCF-3 in rodent behavioral models of depression.

  12. 2-(4-substituted piperazin-1-yl)-1,8-naphthyridine-3-carboxylic acids: novel 5-HT3 receptor antagonists with anxiolytic-like activity in rodent behavioral models.

    PubMed

    Mahesh, Radhakrishnan; Dhar, Arghya Kusum; Jindal, Ankur; Bhatt, Shvetank

    2013-10-01

    The aim of this study was to investigate the anxiolytic potential of a series of novel carboxylic acid based 1,8 naphthyridines as 5-HT3 receptor antagonists. The pA2 values of all the compounds were determined against agonist 2-methyl-5-hydroxytryptamine in longitudinal muscle myenteric plexus preparations from guinea pig ileum. Compounds with higher pA2 values, particularly those greater than ondansetron, a standard 5-HT3 receptor antagonist, and optimal log P values were screened in mice by using behavioral tests such as a light-dark (L/D) aversion test, elevated plus maze (EPM) test, and an open field test (OFT). In the L/D test, compounds 7a, 7b, 7d, 7e, and 7i (2 mg/kg body mass, intraperitoneal) significantly (P < 0.05) increased the latency time to leave the light compartment, total time spent in the light compartment, and the number of transitions between the light and dark compartments. Compounds 7a, 7d, 7f, 7h, and 7i (2 mg/kg, i.p.) significantly (P < 0.05) increased the time spent in the open arms and the number of entries into the open arms in the EPM test. In addition, compounds 7a, 7d, 7e, 7f, and 7h (2 mg/kg, i.p.) significantly (P < 0.05) increased the ambulation scores and the frequency of rearing in the OFT.

  13. Chemotherapy-induced nausea and vomiting and antiemetic prophylaxis with palonosetron versus other 5-HT3 receptor antagonists in patients with cancer treated with low emetogenic chemotherapy in a hospital outpatient setting in the United States.

    PubMed

    Schwartzberg, Lee; Morrow, Gary; Balu, Sanjeev; Craver, Chris; Gayle, Julie; Cox, David

    2011-08-01

    The incidence of overall (acute and delayed) chemotherapy-induced nausea and vomiting (CINV) events among patients treated with single- and multi-day low emetogenic chemotherapy (LEC) is not well established. We studied a cohort of patients receiving LEC and antiemetic prophylaxis with palonosetron (Group 1) versus other 5-HT(3) receptor antagonists (5-HT(3)-RAs) (Group 2), to determine the overall rate of CINV and the proportion of patients experiencing delayed CINV (days 2-7 of a CT cycle) in a hospital outpatient setting. Patients aged ≥18 years with cancer diagnosis initiating single-day and multi-day LEC for the first time between 4/1/2007 and 3/31/2009 were identified from the Premier Perspective database. CINV events (ICD-9-CM codes for nausea, vomiting, or volume depletion or CINV-related rescue medications) were assessed descriptively. A generalized linear multivariate regression model was developed, estimating the overall CINV event rate among Group 1 and 2 patients in the follow-up period (first of eight chemotherapy [CT] cycles or 6 months). In the follow-up period, out of a total of 10,137 overall CINV events (single-day and multi-day LEC), 8783 events (86.6%) were identified in single-day LEC treated patients. Within single-day LEC treated events, in the first cycle, of 3184 events, 2996 (94.1%) events were delayed. Average number of delayed events per patient remained consistent throughout the eight cycles (3.1 [1st cycle] vs. 2.9 [8th cycle]; P = 0.842]). Among 2439 patients on antiemetic prophylaxis with a 5-HT(3)-RA, 10.1% (n = 247) initiated palonosetron. Regression analysis indicated that Group 1 patients (versus Group 2) had a 15.2% reduction in CINV event rate per CT cycle; P = 0.0403. Study limitations include potential lack of generalizability, absence of data on certain confounders including alcohol consumption and prior history of motion sickness, potential underestimation of incidence of uncontrolled CINV, and inability to

  14. Presynaptic 5-HT3 receptor-mediated modulation of synaptic GABA release in the mechanically dissociated rat amygdala neurons

    PubMed Central

    Koyama, Susumu; Matsumoto, Nozomu; Kubo, Chiharu; Akaike, Norio

    2000-01-01

    Nystatin-perforated patch recordings were made from mechanically dissociated basolateral amygdala neurons with preserved intact native presynaptic nerve terminals to study the mechanism of 5-HT3 receptor-mediated serotonergic modulation of GABAergic inhibition. The specific 5-HT3 agonist mCPBG (1 μM) rapidly facilitated the frequency of GABAergic miniature inhibitory postsynaptic currents (mIPSCs) and this facilitation desensitized within 1 min. Tropisetron (30 nM), a specific 5-HT3 antagonist, blocked the mCPBG effect. mCPBG augmented mIPSC amplitude. However, no direct postsynaptic serotonergic currents were evoked by mCPBG. Neither GABA-evoked current amplitude nor the kinetics of individual GABAergic mIPSCs were affected by mCPBG. Therefore, the augmentation is unlikely to be due to postsynaptic effects evoked by mCPBG. At higher concentrations mCPBG produced shorter-duration facilitation of miniature events. While mCPBG increased the mIPSC frequency in calcium-containing solution with Cd2+, this increase was absent in Ca2+-free external solution. It appears that the Ca2+ influx through voltage-dependent calcium channels was not as crucial as that through 5-HT3 receptors for synaptic GABA release. When two pulses of mCPBG (each 1 μM, 1 min) were given, the response to the second pulse elicited full recovery when the interval between pulses was at least 9 min. Protein kinase A (PKA) activation by 8-Br-cAMP (300 μM) shortened and PKA inhibition by Rp-cAMP (100 μM) prolonged the recovery time. PKA activity did not affect the time course of fast desensitization. Our results suggest that a 5-HT3-specific agonist acts on presynaptic nerve terminals facilitating synaptic GABA release without postsynaptic effects. The facilitation requires calcium influx through presynaptic 5-HT3 receptors. PKA modulates the recovery process from desensitization of presynaptic 5-HT3 receptor-mediated regulation of synaptic GABA release. PMID:11101647

  15. Neuropharmacological effect of novel 5-HT3 receptor antagonist, N-n-propyl-3-ethoxyquinoxaline-2-carboxamide (6n) on chronic unpredictable mild stress-induced molecular and cellular response: Behavioural and biochemical evidences.

    PubMed

    Bhatt, Shvetank; Mahesh, Radhakrishnan; Jindal, Ankur; Devadoss, Thangaraj

    2014-10-01

    Chronic unpredictable stressors can produce a situation similar to human depression and such animal models can be used for the preclinical evaluation of antidepressants. The 5-HT3 receptor antagonists modulate serotonergic pathways and show antidepressant-like effect in various animal models of depression. In this study, a novel and potential 5-HT3 receptor antagonist N-n-propyl-3-ethoxyquinoxaline-2-carboxamide (6n) with good Log P (2.52) value and pA2 (7.6) values, synthesized in our laboratory was explore to study the effects on CUMS-induced behavioural and biochemical alterations in mice. Mice were subjected to different stress paradigms daily for a period of 28 days to induce depressive-like behaviour. CUMS caused depression-like behaviour in mice, as indicated by the significant decrease in sucrose consumption and increase in immobility time in the forced swim test (FST) while there was no significant effect on spontaneous locomotor activity (SLA) observed. In addition it was found that lipid peroxide and nitrite levels were significantly increased, whereas glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) levels were decreased in brain tissue of CUMS-treated mice. Compound 6n (1 and 2mg/kg, po, 21 days) and fluoxetine treatment (20mg/kg, po, 21 days) significantly altered the CUMS-induced behavioural (increased immobility period, reduced sucrose preference) and biochemical (increased lipid peroxidation, increased brain nitrite; decreased GSH, SOD and CAT levels) parameters while there was no significant effect of observed on SLA. Compound 6n produced antidepressant-like effects in behavioural despair paradigm in chronically stressed mice by restoring antioxidant enzyme activity up to significant level. Copyright © 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  16. Role of 5-HT3 receptors in basal and K(+)-evoked dopamine release from rat olfactory tubercle and striatal slices.

    PubMed Central

    Zazpe, A; Artaiz, I; Del Río, J

    1994-01-01

    1. The present study was aimed at examining the role of 5-HT3 receptors in basal and depolarization-evoked dopamine release from rat olfactory tubercle and striatal slices. [3H]-dopamine ([3H]-DA) release was measured in both brain regions and endogenous dopamine release from striatal slices was also studied. 2. The selective 5-HT3 receptor agonist 2-methyl-5-HT (0.5-10 microM) produced a concentration-dependent increase in [3H]-DA efflux evoked by K+ (20 mM) from slices of rat olfactory tubercle. 1-Phenylbiguanide (PBG) and 5-HT also increased K(+)-evoked [3H]-DA efflux. 3. 5-HT (1-100 microM) increased in a concentration-dependent manner basal [3H]-DA release from olfactory tubercle and striatal slices as well as endogenous DA release from striatal slices. The selective 5-HT3 receptor agonists 2-methyl-5-HT and 1-phenylbiguanide were weaker releasing agents. In all cases, the release was Ca2+ independent and tetrodotoxin insensitive. 4. 5-HT3 receptor antagonists such as ondansetron, granisetron and tropisetron (0.2 microM) significantly blocked the enhanced K(+)-evoked [3H]-DA efflux from rat olfactory tubercle slices induced by 2-methyl-5HT. A ten fold higher concentration of the 5-HT2 receptor antagonist ketanserin was ineffective. 5. Much higher concentrations, up to 50 microM, of the same 5-HT3 receptor antagonists did not block the increase in basal [3H]-DA release from striatal or olfactory tubercle slices induced by 5-HT or the release of endogenous DA induced by 5-HT from striatal slices.2+ off PMID:7858893

  17. Structural basis of ligand recognition in 5-HT3 receptors

    PubMed Central

    Kesters, Divya; Thompson, Andrew J; Brams, Marijke; van Elk, René; Spurny, Radovan; Geitmann, Matthis; Villalgordo, Jose M; Guskov, Albert; Helena Danielson, U; Lummis, Sarah C R; Smit, August B; Ulens, Chris

    2013-01-01

    The 5-HT3 receptor is a pentameric serotonin-gated ion channel, which mediates rapid excitatory neurotransmission and is the target of a therapeutically important class of anti-emetic drugs, such as granisetron. We report crystal structures of a binding protein engineered to recognize the agonist serotonin and the antagonist granisetron with affinities comparable to the 5-HT3 receptor. In the serotonin-bound structure, we observe hydrophilic interactions with loop E-binding site residues, which might enable transitions to channel opening. In the granisetron-bound structure, we observe a critical cation–π interaction between the indazole moiety of the ligand and a cationic centre in loop D, which is uniquely present in the 5-HT3 receptor. We use a series of chemically tuned granisetron analogues to demonstrate the energetic contribution of this electrostatic interaction to high-affinity ligand binding in the human 5-HT3 receptor. Our study offers the first structural perspective on recognition of serotonin and antagonism by anti-emetics in the 5-HT3 receptor. PMID:23196367

  18. Menthol inhibits 5-HT3 receptor-mediated currents.

    PubMed

    Ashoor, Abrar; Nordman, Jacob C; Veltri, Daniel; Yang, Keun-Hang Susan; Shuba, Yaroslav; Al Kury, Lina; Sadek, Bassem; Howarth, Frank C; Shehu, Amarda; Kabbani, Nadine; Oz, Murat

    2013-11-01

    The effects of alcohol monoterpene menthol, a major active ingredient of the peppermint plant, were tested on the function of human 5-hydroxytryptamine type 3 (5-HT3) receptors expressed in Xenopus laevis oocytes. 5-HT (1 μM)-evoked currents recorded by two-electrode voltage-clamp technique were reversibly inhibited by menthol in a concentration-dependent (IC50 = 163 μM) manner. The effects of menthol developed gradually, reaching a steady-state level within 10-15 minutes and did not involve G-proteins, since GTPγS activity remained unaltered and the effect of menthol was not sensitive to pertussis toxin pretreatment. The actions of menthol were not stereoselective as (-), (+), and racemic menthol inhibited 5-HT3 receptor-mediated currents to the same extent. Menthol inhibition was not altered by intracellular 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid injections and transmembrane potential changes. The maximum inhibition observed for menthol was not reversed by increasing concentrations of 5-HT. Furthermore, specific binding of the 5-HT3 antagonist [(3)H]GR65630 was not altered in the presence of menthol (up to 1 mM), indicating that menthol acts as a noncompetitive antagonist of the 5-HT3 receptor. Finally, 5-HT3 receptor-mediated currents in acutely dissociated nodose ganglion neurons were also inhibited by menthol (100 μM). These data demonstrate that menthol, at pharmacologically relevant concentrations, is an allosteric inhibitor of 5-HT3 receptors.

  19. Tropisetron suppresses colitis-associated cancer in a mouse model in the remission stage.

    PubMed

    Amini-Khoei, Hossein; Momeny, Majid; Abdollahi, Alireza; Dehpour, Ahmad Reza; Amiri, Shayan; Haj-Mirzaian, Arya; Tavangar, Seyed Mohammad; Ghaffari, Seyed Hamid; Rahimian, Reza; Mehr, Shahram Ejtemaei

    2016-07-01

    Patients with inflammatory bowel disease (IBD) have a high risk for development of colitis-associated cancer (CAC). Serotonin is a neurotransmitter produced by enterochromaffin cells of the intestine. Serotonin and its receptors, mainly 5-HT3 receptor, are overexpressed in IBD and promote development of CAC through production of inflammatory cytokines. In the present study, we demonstrated the in vivo activity of tropisetron, a 5-HT3 receptor antagonist, against experimental CAC. CAC was induced by azoxymethane (AOM)/dextran sodium sulfate (DDS) in BALB/c mice. The histopathology of colon tissue was performed. Beta-catenin and Cox-2 expression was evaluated by immunohistochemistry as well as quantitative reverse transcription-PCR (qRT-PCR). Alterations in the expression of 5-HT3 receptor and inflammatory-associated genes such as Il-1β, Tnf-α, Tlr4 and Myd88 were determined by qRT-PCR. Our results showed that tumor development in tropisetron-treated CAC group was significantly lower than the controls. The qRT-PCR analysis demonstrated that the expression of 5-HT3 receptor was significantly increased following CAC induction. In addition, tropisetron reduced expression of β-catenin and Cox-2 in the CAC experimental group. The levels of Il-1β, Tnf-α, Tlr4 and Myd88 were significantly decreased upon tropisetron treatment in the AOM/DSS group. Taken together, our data show that tropisetron inhibits development of CAC probably by attenuation of inflammatory reactions in the colitis. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Neuropharmacological evaluation of a novel 5-HT3 receptor antagonist (6g) on chronic unpredictable mild stress-induced changes in behavioural and brain oxidative stress parameters in mice

    PubMed Central

    Bhatt, Shvetank; Radhakrishnan, Mahesh; Jindal, Ankur; Devadoss, Thangaraj; Dhar, Arghya Kusum

    2014-01-01

    Aim: The aim of the study was to evaluate a novel 5 HT3 receptor antagonist (6g) on chronic stress induced changes in behavioural and brain oxidative stress parameter in mice. A complicated relationship exists among stressful stimuli, body's reaction to stress and the onset of clinical depression. Chronic unpredictable stressors can produce a situation similar to human depression, and such animal models can be used for the preclinical evaluation of antidepressants. Materials and Methods: In the present study, a novel and potential 5-HT3 receptor antagonist (4-benzylpiperazin-1-yl)(3-methoxyquinoxalin-2-yl) methanone (6g) with good Log P (3.08) value and pA2(7.5) values, synthesized in our laboratory was investigated to study the effects on chronic unpredictable mild stress (CUMS)-induced behavioural and biochemical alterations in mice. Mice were subjected to different stress paradigms daily for a period of 28 days to induce depressive-like behaviour. Results: The results showed that CUMS caused depression-like behaviour in mice, as indicated by the significant (P < 0.05) decrease in sucrose consumption and locomotor activity and increase in immobility the forced swim test. In addition, it was found that lipid peroxidation and nitrite levels were significantly (P < 0.05) increased, whereas glutathione levels, superoxide dismutase and catalase activities decreased in brain tissue of CUMS-treated mice. ‘6g’ (1 and 2 mg/kg, p.o., 21 days) and fluoxetine treatment (20 mg/kg, p.o., 21 days) significantly (P < 0.05) reversed the CUMS-induced behavioural (increased immobility period, reduced sucrose preference and decreased locomotor activity) and biochemical (increased lipid peroxidation; decreased glutathione levels, superoxide dismutase and catalase activities). However fluoxetine treatment (20 mg/kg, p.o., 21 days) significantly decreased the nitrite level in the brain while ‘6g’ (1 and 2 mg/kg, p.o., 21 days) did not show significant (P < 0.05) effect on the

  1. Sleep Deprivation-Induced Blood-Brain Barrier Breakdown and Brain Dysfunction are Exacerbated by Size-Related Exposure to Ag and Cu Nanoparticles. Neuroprotective Effects of a 5-HT3 Receptor Antagonist Ondansetron.

    PubMed

    Sharma, Aruna; Muresanu, Dafin F; Lafuente, José V; Patnaik, Ranjana; Tian, Z Ryan; Buzoianu, Anca D; Sharma, Hari S

    2015-10-01

    Military personnel are often subjected to sleep deprivation (SD) during combat operations. Since SD is a severe stress and alters neurochemical metabolism in the brain, a possibility exists that acute or long-term SD will influence blood-brain barrier (BBB) function and brain pathology. This hypothesis was examined in young adult rats (age 12 to 14 weeks) using an inverted flowerpot model. Rats were placed over an inverted flowerpot platform (6.5 cm diameter) in a water pool where the water levels are just 3 cm below the surface. In this model, animals can go to sleep for brief periods but cannot achieve deep sleep as they would fall into water and thus experience sleep interruption. These animals showed leakage of Evans blue in the cerebellum, hippocampus, caudate nucleus, parietal, temporal, occipital, cingulate cerebral cortices, and brain stem. The ventricular walls of the lateral and fourth ventricles were also stained blue, indicating disruption of the BBB and the blood-cerebrospinal fluid barrier (BCSFB). Breakdown of the BBB or the BCSFB fluid barrier was progressive in nature from 12 to 48 h but no apparent differences in BBB leakage were seen between 48 and 72 h of SD. Interestingly, rats treated with metal nanoparticles, e.g., Cu or Ag, showed profound exacerbation of BBB disruption by 1.5- to 4-fold, depending on the duration of SD. Measurement of plasma and brain serotonin showed a close correlation between BBB disruption and the amine level. Repeated treatment with the serotonin 5-HT3 receptor antagonist ondansetron (1 mg/kg, s.c.) 4 and 8 h after SD markedly reduced BBB disruption and brain pathology after 12 to 24 h SD but not following 48 or 72 h after SD. However, TiO2-nanowired ondansetron (1 mg/kg, s.c) in an identical manner induced neuroprotection in rats following 48 or 72 h SD. However, plasma and serotonin levels were not affected by ondansetron treatment. Taken together, our observations are the first to show that (i) SD could induce BBB

  2. Involvement of nitric oxide-cyclic guanosine monophosphate pathway in the antidepressant-like effect of tropisetron and ondansetron in mice forced swimming test and tail suspension test.

    PubMed

    Haj-Mirzaian, Arya; Kordjazy, Nastaran; Amiri, Shayan; Haj-Mirzaian, Arvin; Amini-Khoei, Hossien; Ostadhadi, Sattar; Dehpour, AhmadReza

    2016-06-05

    Antidepressant-like effects of 5-hydroxytryptamine subtype 3 (5-HT3) antagonists including tropisetron and ondansetron have been previously demonstrated in the literature. It was reported that stimulation of 5-HT3 receptors activate the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway, which is involved in regulation of behavioral and emotional functions. In our study, treating animals with tropisetron (5, 10, and 30mg/kg) and ondansetron (0.01 and 0.1µg/kg) significantly decreased the immobility time in forced swimming test (FST) and tail-suspension test (TST). Co-administration of subeffective doses of tropisetron (1mg/kg) and ondansetron (0.001µg/kg) with subeffective dose of l-NAME (10mg/kg, nonselective NO synthase (NOS) inhibitor) and 7-nitroindazole (25mg/kg, neural NOS inhibitor) exerted antidepressant-like effect in FST and TST, while aminoguanidine (50mg/kg, inducible NOS inhibitor) did not enhance the antidepressant-like effect of 5-HT3 antagonists. Besides, l-arginine (750mg/kg, NO precursor) and sildenafil (5mg/kg, phosphodiesterase inhibitor) suppressed the anti-immobility effect of 5-HT3 antagonists. None of the treatments altered the locomotor behavior of mice in open-field test. Also, hippocampal (but not cortical) nitrite level was significantly lower in tropisetron and ondansetron-treated mice compared with saline-injected mice. Also, co-administration of 7-nitroindazole with tropisetron or ondansetron caused a significant decrease in hippocampal nitrite levels. In conclusion, we suggest that antidepressant-like effect of tropisetron and ondansetron are partially mediated by modulation of NO-cGMP pathway.

  3. Antidepressant-like activity of (4-phenylpiperazin-1-yl) (quinoxalin-2-yl) methanone (4a), a novel 5-HT(3) receptor antagonist: an investigation in behaviour-based rodent models of depression.

    PubMed

    Mahesh, Radhakrishnan; Kumar, Baldev; Jindal, Ankur; Bhatt, Shvetank; Devadoss, Thangaraj; Pandey, Dilip Kumar

    2012-01-01

    The present study was designed to investigate the antidepressant potential of (4-phenylpiperazin-1-yl) (quinoxalin-3-yl) methanone (4a), a novel 5-HT(3) receptor antagonist, with an optimal log P (2.84) and pA(2) value (7.3) greater than ondansetron (6.9) using rodent behavioural models of depression. Swiss albino mice were used in actophotometer test, forced swim test (FST) and 5-hydroxytryptophan (5-HTP) induced head twitch response. Reserpine induced hypothermia (RIH) and olfactory bulbectomy were performed in male Wistar rats. Statistical analysis was carried out by using one-way analysis of variance followed by Tukey's test. Acute treatment of 4a (1-4 mg/kg, i.p.) in mice produced antidepressant-like effects in FST without affecting the baseline locomotion in actophotometer test. Further, 4a (2-4 mg/kg, i.p.) potentiated the 5-HTP induced head twitches response in mice and also antagonized RIH in rats. Furthermore, sub-chronic (14 days) treatment with 4a (2-4 mg/ kg, p.o.) significantly attenuated the behavioural anomalies induced by bilateral olfactory bulbectomy in rats in modified open field exploration. These preliminary investigations confirm that 4a exhibits antidepressant-like activity in behaviour based rodent models of depression.

  4. Inhibitory effects of ramosetron, a potent and selective 5-HT3-receptor antagonist, on conditioned fear stress-induced abnormal defecation and normal defecation in rats: comparative studies with antidiarrheal and spasmolytic agents.

    PubMed

    Hirata, Takuya; Funatsu, Toshiyuki; Keto, Yoshihiro; Akuzawa, Shinobu; Sasamata, Masao; Miyata, Keiji

    2008-02-01

    We examined the effect of ramosetron, a potent serotonin (5-HT)(3)-receptor antagonist for irritable bowel syndrome with diarrhea, on conditioned fear stress (CFS)-induced defecation and normal (non-stressed) defecation in rats and compared ramosetron with the antidiarrheal agent loperamide and the spasmolytic agents trimebutine and tiquizium. Ramosetron, loperamide, trimebutine, and tiquizium significantly inhibited CFS-induced defecation in a dose-dependent manner with ED(50) (95% confidence limit) values of 0.019 (0.01 - 0.028), 9.4 (4.0 - 22), 850 (520 - 2,400), and 300 (190 - 450) mg/kg, respectively. A significant effect of ramosetron on CFS-induced defecation appeared at 10 min after dosing and was sustained for 8 h. In contrast, loperamide, trimebutine, and tiquizium significantly inhibited CFS-induced defecation between 1 - 8, 1 - 4, and 1 - 8 h after administration, respectively. High doses of ramosetron did not affect normal defecation, whereas loperamide, trimebutine, and tiquizium significantly inhibited this process. In conclusion, ramosetron has potent, rapid-onset, and long-lasting inhibitory effects on CFS-induced defecation in rats, but does not influence normal defecation. The present findings indicate that ramosetron will be a useful therapeutic agent for irritable bowel syndrome with diarrhea, showing greater efficacy and safety than other antidiarrheal and spasmolytic agents.

  5. Structural, conformational, biochemical, and pharmacological study of some amides derived from 3,7-dimethyl-3,7-diazabicyclo [3.3.1] nonan-9-amine as potential 5-HT 3 receptor antagonists

    NASA Astrophysics Data System (ADS)

    Fernández, M. J.; Huertas, R. M.; Gálvez, E.; Orjales, A.; Berisa, A.; Labeaga, L.; Garcia, A. G.; Uceda, G.; Server-Carrió, J.; Martinez-Ripoll, M.

    1995-12-01

    A series of amides derived from 3,7-dimethyl-3,7-diazabicyclo [3.3.1] nonan-9-amine have been synthesized and examined by 1H and 13C NMR spectroscopy and the crystal structure of 9-(2,4,6-trichlorobenzamido)-3,7-dimethyl-3,7-diazabicyclo[3.3.1] nonane hydrochloride ( 4a·HCl) has been determined by X-ray diffraction. These compounds adopt an almost perfect chair-chair conformation with the NCH 3 groups in equatorial position. This conformation is nearly the same as that observed for compound 4a in the solid state. From binding studies of compounds 4a-c, compound 4b demonstrated the ability to efficiently displace [ 3H]GR65630 bound to bovine brain area postrema membranes to an extent comparable to MDL 72222. In the von Bezold-Jarish reflex, compound 4b showed significant results at a dose of 25 mg Kg -1. It is shown for the first time that a series of compounds with a bispidine skeleton linked through an amide moiety to several aromatic rings, shows 5-HT 3 antagonistic profiles.

  6. Effect of (4a) a novel 5-HT3 receptor antagonist on chronic unpredictable mild stress induced depressive-like behavior in mice: an approach using behavioral tests battery.

    PubMed

    Kurhe, Yeshwant; Mahesh, Radhakrishnan; Gupta, Deepali; Thangaraj, Devadoss

    2015-01-01

    The inconsistent therapeutic outcome necessitates designing and identifying novel therapeutic interventions for depression. Hence, the present study deals with the investigation of antidepressant-like effects of a novel 5-HT3 receptor antagonist (4-phenylpiperazin-1-yl) (quinoxalin-2-yl) methanone (4a) on chronic unpredictable mild stress (CUMS) induced behavioral and biochemical alterations. Animals were subjected to different stressors for a period of 28 days. On day 15 after the subsequent stress procedure, mice were administered with (4a) (2 and 4 mg/kg p.o.), escitalopram (10 mg/kg p.o.), or vehicle (10 mL/kg p.o.) until day 28 along with the CUMS. Thereafter, behavioral battery tests like locomotor score, sucrose preference test, forced swim test (FST), tail suspension test (TST), and elevated plus maze (EPM) were performed. Biochemical assays like lipid peroxidation, nitrite levels, reduced glutathione (GSH), catalase, and superoxide dismutase (SOD) were estimated in the mice brain homogenate. (4a) Dose dependently attenuated the behavioral alterations by increasing the sucrose consumption, reducing the immobility time in FST and TST, increasing the open arm number of entries and time in EPM. Furthermore, biochemical alterations were reversed by (4a) as examined by reduced lipid peroxidation and nitrite levels and elevated antioxidant enzyme levels like GSH, catalase and SOD. (4a) exhibits antidepressant potential by reversing the CUMS induced behavioral and biochemical changes in mice.

  7. The effect of paracetamol and tropisetron on pain: experimental studies and a review of published data.

    PubMed

    Tiippana, Elina; Hamunen, Katri; Kontinen, Vesa; Kalso, Eija

    2013-02-01

    Experimental studies suggest that paracetamol-induced analgesia is mediated via central serotonergic pathways and attenuated by 5-HT3-antagonists. However, clinical studies do not support this, and 5-HT3-antagonists are expected to reduce pain by blocking the descending pronociceptive pathway. The current project tested whether tropisetron attenuates analgesia by paracetamol. Two randomized, double-blind, crossover studies with 18 healthy male volunteers in each were performed. Pain stimuli were cold water immersion (cold pressor test), contact heat pain (study 1) and electrical stimulation (study 2). In both studies, tropisetron 5 mg i.v. or saline was administered, followed by paracetamol 2 g i.v. 30 min. later. Individual changes in heat and cold pain intensity, cold pain tolerance and unpleasantness were recorded. The same thresholds were also expressed as scores (% of the individual score at baseline). Additionally, previously published findings on the effects of paracetamol and its interaction with 5HT3-antagonists in human experimental pain models were reviewed. After calculation of the sensory and pain scores (%), tropisetron seemed to amplify the analgesic action of paracetamol. Paracetamol 2 g i.v. did not show any statistically significant analgesia in thermal tests (study 1), or differences in sensory, pain detection or moderate pain thresholds of the electrical stimulus (study 2). As paracetamol did not have a measurable analgesic effect in these tests, no conclusions can be drawn about the interaction between paracetamol and tropisetron. However, tropisetron may have an analgesic effect of its own. Clinicians should not avoid using these drugs together, unless larger clinical studies indicate otherwise.

  8. Effect of intravenous tropisetron on modulation of pain and central hypersensitivity in chronic low back pain patients.

    PubMed

    Neziri, Alban Y; Dickenmann, Martina; Scaramozzino, Pasquale; Andersen, Ole K; Arendt-Nielsen, Lars; Dickenson, Anthony H; Curatolo, Michele

    2012-02-01

    The activation of 5-hydroxytryptamine-3 (5-HT-3) receptors in spinal cord can enhance intrinsic spinal mechanisms of central hypersensitivity, possibly leading to exaggerated pain responses. Clinical studies suggest that 5-HT-3 receptor antagonists may have an analgesic effect. This randomized, double-blind, placebo-controlled crossover study tested the hypothesis that the 5-HT-3 receptor antagonist tropisetron attenuates pain and central hypersensitivity in patients with chronic low back pain. Thirty patients with chronic low back pain, 15 of whom were women (aged 53 ± 14 years) and 15 men (aged 48 ± 14 years), were studied. A single intravenous injection of 0.9% saline solution, tropisetron 2mg, and tropisetron 5mg was administrated in 3 different sessions, in a double-blind crossover manner. The main outcome was the visual analogue scale (VAS) score of spontaneous low back pain before, and 15, 30, 60, and 90 minutes after drug administration. Secondary outcomes were nociceptive withdrawal reflexes to single and repeated electrical stimulation, area of reflex receptive fields, pressure pain detection and tolerance thresholds, conditioned pain modulation, and area of clinical pain. The data were analyzed by analysis of variance and panel multiple regressions. All 3 treatments reduced VAS scores. However, there was no statistically significant difference between tropisetron and placebo in VAS scores. Compared to placebo, tropisetron produced a statistically significant increase in pain threshold after single electrical stimulation, but no difference in all other secondary outcomes was found. A single-dose intravenous administration of tropisetron in patients with chronic low back pain had no significant specific effect on intensity of pain and most parameters of central hypersensitivity.

  9. P2X3 receptors induced inflammatory nociception modulated by TRPA1, 5-HT3 and 5-HT1A receptors.

    PubMed

    Krimon, Suzy; Araldi, Dionéia; do Prado, Filipe César; Tambeli, Cláudia Herrera; Oliveira-Fusaro, Maria Cláudia G; Parada, Carlos Amílcar

    2013-11-01

    It has been described that endogenous ATP via activation of P2X3 and P2X2/3 receptors contributes to inflammatory nociception in different models, including the formalin injected in subcutaneous tissue of the rat's hind paw. In this study, we have evaluated whether TRPA1, 5-HT3 and 5-HT1A receptors, whose activation is essential to formalin-induced inflammatory nociception, are involved in the nociception induced by activation of P2X3 receptors on subcutaneous tissue of the rat's hind paw. We have also evaluated whether the activation of P2X3 receptors increases the susceptibility of primary afferent neurons to formalin action modulated by activation of TRPA1, 5-HT3 or 5-HT1A receptors. Nociceptive response intensity was measured by observing the rat's behavior and considering the number of times the animal reflexively raised its hind paw (flinches) in 60min. Local subcutaneous administration of the selective TRPA1, 5-HT3 or 5-HT1A receptor antagonists HC 030031, tropisetron and WAY 100,135, respectively, prevented the nociceptive responses induced by the administration in the same site of the non-selective P2X3 receptor agonist αβmeATP. Administration of the selective P2X3 and P2X2/3 receptor antagonist A-317491 or pretreatment with oligonucleotides antisense against P2X3 receptor prevented the formalin-induced behavioral nociceptive responses during the first and second phases. Also, the co-administration of a subthreshold dose of αβmeATP with a subthreshold dose of formalin induced nociceptive behavior, which was prevented by local administration of tropisetron, HC 030031 or WAY 100, 135. These findings have demonstrated that the activation of P2X3 receptors induces inflammatory nociception modulated by TRPA1, 5-HT3 and 5-HT1A receptors. Also, they suggest that inflammatory nociception is modulated by the release of endogenous ATP and P2X3 receptor activation, which in turn, increases primary afferent nociceptor susceptibility to the action of inflammatory

  10. Antidepressant-like effect of a novel 5-HT3 receptor antagonist N-(benzo[d] thiazol-2-yl)-3-ethoxyquinoxalin-2-carboxamide 6k using rodents behavioral battery tests.

    PubMed

    Kurhe, Yeshwant; Mahesh, Radhakrishnan; Devadoss, Thangaraj; Gupta, Deepali

    2014-07-01

    To investigate the antidepressant-like effect of N-(benzo[d] thiazol-2-yl)-3- ethoxyquinoxalin-2-carboxamide 6k, a 5-hydroxytryptamine type 3 (5-HT3) receptor antagonist using rodents behavioral battery tests. 6k screening was performed with behavioral assays for depression-like forced swim test (FST) at several single doses (0.25-4 mg/kg, intraperitoneal injection (i.p.)) to test the potency of 6k, in which 2 and 4 mg/kg doses were found to be most effective and hence, in further behavioral assays including mechanistic model like 5-hydroxytryptophan (5-HTP)-induced head twitches was performed in mice at acute doses of 6k (2 and 4 mg/kg, i.p.). Furthermore, olfactory bulbectomy (OBX), a surgical model-induced behavioral alterations was performed in rats, and the effect of 6k administered orally (2 and 4 mg/kg, p.o.) after subchronic treatment for 14 days starting from day 15 of postsurgery was examined by percent sucrose preference test and modified open field test (OFT). 6k (1, 2, and 4 mg/kg, i.p.) reduced the immobility time and increased the swimming behavior in FST without affecting the baseline locomotor score showing antidepressant-like effect. 5-HTP-induced head twitch response was potentiated by 6k (2 and 4 mg/kg, i.p.), which indicated rise in the serotonergic neurotransmission in the brain. 6k (2 and 4 mg/kg, p.o.) showed anti-anhedonia effect by increasing the sucrose consumption and reversed the behavioral alterations when exposed to modified open field in OBX rats after subchronic treatment for 14 days, thus exhibiting antidepressant-like effect. 6k attenuated the behavioral derangement in rodents-based behavioral battery tests for depression, indicating antidepressant-like potential.

  11. Antidepressant-like effect of a novel 5-HT3 receptor antagonist N-(benzo[d] thiazol-2-yl)-3-ethoxyquinoxalin-2-carboxamide 6k using rodents behavioral battery tests

    PubMed Central

    Kurhe, Yeshwant; Mahesh, Radhakrishnan; Devadoss, Thangaraj; Gupta, Deepali

    2014-01-01

    Objective: To investigate the antidepressant-like effect of N-(benzo[d] thiazol-2-yl)-3- ethoxyquinoxalin-2-carboxamide 6k, a 5-hydroxytryptamine type 3 (5-HT3) receptor antagonist using rodents behavioral battery tests. Materials and Methods: 6k screening was performed with behavioral assays for depression-like forced swim test (FST) at several single doses (0.25-4 mg/kg, intraperitoneal injection (i.p.)) to test the potency of 6k, in which 2 and 4 mg/kg doses were found to be most effective and hence, in further behavioral assays including mechanistic model like 5-hydroxytryptophan (5-HTP)-induced head twitches was performed in mice at acute doses of 6k (2 and 4 mg/kg, i.p.). Furthermore, olfactory bulbectomy (OBX), a surgical model-induced behavioral alterations was performed in rats, and the effect of 6k administered orally (2 and 4 mg/kg, p.o.) after subchronic treatment for 14 days starting from day 15 of postsurgery was examined by percent sucrose preference test and modified open field test (OFT). Results: 6k (1, 2, and 4 mg/kg, i.p.) reduced the immobility time and increased the swimming behavior in FST without affecting the baseline locomotor score showing antidepressant-like effect. 5-HTP-induced head twitch response was potentiated by 6k (2 and 4 mg/kg, i.p.), which indicated rise in the serotonergic neurotransmission in the brain. 6k (2 and 4 mg/kg, p.o.) showed anti-anhedonia effect by increasing the sucrose consumption and reversed the behavioral alterations when exposed to modified open field in OBX rats after subchronic treatment for 14 days, thus exhibiting antidepressant-like effect. Conclusion: 6k attenuated the behavioral derangement in rodents-based behavioral battery tests for depression, indicating antidepressant-like potential. PMID:25210400

  12. Design, synthesis, and pharmacological evaluation of novel 2-(4-substituted piperazin-1-yl)1, 8 naphthyridine 3-carboxylic acids as 5-HT3 receptor antagonists for the management of depression.

    PubMed

    Dhar, Arghya K; Mahesh, Radhakrishnan; Jindal, Ankur; Devadoss, Thangaraj; Bhatt, Shvetank

    2014-12-01

    1, 8-naphthyridine-3-carboxylic acid analogs were synthesized and found to possess potential 5-HT3 receptor antagonism as well as antidepressant-like activity. Initially, 5-HT3 receptor antagonism of all the compounds was determined in the form of pA2 value against agonist 2-methyl 5-HT in longitudinal muscle-myenteric plexus preparation from guinea-pig ileum. Among all the compounds tested, compound 7a demonstrated most promising pA2 value of 7.6. Subsequently, all the compounds were evaluated for antidepressant activity using forced swim test and tail suspension test in mice. Compounds 7a, 7d, 7f, 7h, and 7i exhibited significant (p < 0.05) antidepressant-like activity as compound to vehicle-treated group. Importantly, none of the tested compound affected locomotor activity of mice at tested dose levels.

  13. The Role of 5-HT3 Receptors in Signaling from Taste Buds to Nerves.

    PubMed

    Larson, Eric D; Vandenbeuch, Aurelie; Voigt, Anja; Meyerhof, Wolfgang; Kinnamon, Sue C; Finger, Thomas E

    2015-12-02

    Activation of taste buds triggers the release of several neurotransmitters, including ATP and serotonin (5-hydroxytryptamine; 5-HT). Type III taste cells release 5-HT directly in response to acidic (sour) stimuli and indirectly in response to bitter and sweet tasting stimuli. Although ATP is necessary for activation of nerve fibers for all taste stimuli, the role of 5-HT is unclear. We investigated whether gustatory afferents express functional 5-HT3 receptors and, if so, whether these receptors play a role in transmission of taste information from taste buds to nerves. In mice expressing GFP under the control of the 5-HT(3A) promoter, a subset of cells in the geniculate ganglion and nerve fibers in taste buds are GFP-positive. RT-PCR and in situ hybridization confirmed the presence of 5-HT(3A) mRNA in the geniculate ganglion. Functional studies show that only those geniculate ganglion cells expressing 5-HT3A-driven GFP respond to 10 μM 5-HT and this response is blocked by 1 μM ondansetron, a 5-HT3 antagonist, and mimicked by application of 10 μM m-chlorophenylbiguanide, a 5-HT3 agonist. Pharmacological blockade of 5-HT3 receptors in vivo or genetic deletion of the 5-HT3 receptors reduces taste nerve responses to acids and other taste stimuli compared with controls, but only when urethane was used as the anesthetic. We find that anesthetic levels of pentobarbital reduce taste nerve responses apparently by blocking the 5-HT3 receptors. Our results suggest that 5-HT released from type III cells activates gustatory nerve fibers via 5-HT3 receptors, accounting for a significant proportion of the neural taste response.

  14. The Role of 5-HT3 Receptors in Signaling from Taste Buds to Nerves

    PubMed Central

    Vandenbeuch, Aurelie; Voigt, Anja; Meyerhof, Wolfgang; Kinnamon, Sue C.; Finger, Thomas E.

    2015-01-01

    Activation of taste buds triggers the release of several neurotransmitters, including ATP and serotonin (5-hydroxytryptamine; 5-HT). Type III taste cells release 5-HT directly in response to acidic (sour) stimuli and indirectly in response to bitter and sweet tasting stimuli. Although ATP is necessary for activation of nerve fibers for all taste stimuli, the role of 5-HT is unclear. We investigated whether gustatory afferents express functional 5-HT3 receptors and, if so, whether these receptors play a role in transmission of taste information from taste buds to nerves. In mice expressing GFP under the control of the 5-HT3A promoter, a subset of cells in the geniculate ganglion and nerve fibers in taste buds are GFP-positive. RT-PCR and in situ hybridization confirmed the presence of 5-HT3A mRNA in the geniculate ganglion. Functional studies show that only those geniculate ganglion cells expressing 5-HT3A-driven GFP respond to 10 μm 5-HT and this response is blocked by 1 μm ondansetron, a 5-HT3 antagonist, and mimicked by application of 10 μm m-chlorophenylbiguanide, a 5-HT3 agonist. Pharmacological blockade of 5-HT3 receptors in vivo or genetic deletion of the 5-HT3 receptors reduces taste nerve responses to acids and other taste stimuli compared with controls, but only when urethane was used as the anesthetic. We find that anesthetic levels of pentobarbital reduce taste nerve responses apparently by blocking the 5-HT3 receptors. Our results suggest that 5-HT released from type III cells activates gustatory nerve fibers via 5-HT3 receptors, accounting for a significant proportion of the neural taste response. SIGNIFICANCE STATEMENT Historically, serotonin (5-hydroxytryptamine; 5-HT) has been described as a candidate neurotransmitter in the gustatory system and recent studies show that type III taste receptor cells release 5-HT in response to various taste stimuli. In the present study, we demonstrate that a subset of gustatory sensory neurons express functional

  15. The multi-functional drug tropisetron binds APP and normalizes cognition in a murine Alzheimer’s model

    PubMed Central

    Spilman, Patricia; Descamps, Olivier; Gorostiza, Olivia; Peters-Libeu, Clare; Poksay, Karen S.; Matalis, Alexander; Patent, Alexander; Rao, Rammohan; John, Varghese; Bredesen, Dale E.

    2014-01-01

    Tropisetron was identified in a screen for candidates that increase the ratio of the trophic, neurite-extending peptide sAPPα to the anti-trophic, neurite-retractive peptide Aβ, thus reversing this imbalance in Alzheimer’s disease (AD). We describe a hierarchical screening approach to identify such drug candidates, moving from cell lines to hippocampal neuronal cultures to in vivo studies. By screening a clinical compound library in the primary assay using CHO-7W cells stably transfected with human APPwt, we identified tropisetron as a candidate that consistently increased sAPPα. Secondary assay testing in neuronal cultures from J20 (PDAPP, huAPPSwe/Ind) mice showed that tropisetron consistently increased the sAPPα/Aβ 1-42 ratio. In in vivo studies in J20 mice, tropisetron improved the sAPPα/Aβ ratio along with spatial and working memory in mice, and was effective both during the symptomatic, pre-plaque phase (5-6 months) and in the late plaque phase (14 months). This ameliorative effect occurred at a dose of 0.5 mg/kg/d (mkd), translating to a human-equivalent dose of 5 mg/day, the current dose for treatment of postoperative nausea and vomiting (PONV). Although tropisetron is a 5-HT3 antagonist and an α7nAChR partial agonist, we found that it also binds to the ectodomain of APP. Direct comparison of tropisetron to the current AD therapeutics memantine (Namenda) and donepezil (Aricept), using similar doses for each, revealed that tropisetron induced greater improvements in memory and sAPPα/Aβ1-42. The improvements observed with tropisetron in the J20 AD mouse model, and its known safety profile, suggest that it may be suitable for transition to human trials as a candidate therapeutic for mild cognitive impairment (MCI) and AD, and therefore it has been approved for testing in clinical trials to begin in 2014. PMID:24389031

  16. The involvement of 5-HT3 and 5-HT4 receptors in two models of gastrointestinal transit in mice.

    PubMed

    Pascual, D; Alsasua, A; Goicoechea, C; Martín, M I

    2002-07-05

    Our aim was to study the involvement of 5-hydroxytryptamine (5-HT)(3) and 5-HT(4) receptors in two models of gastrointestinal transit (GIT) in mice: the 5-hydroxytryptophan (5-HTP)-induced diarrhea and intestinal inflammation produced by an irritant agent, croton oil (CO). 5-HTP (10 mg/kg) produced diarrhea that was significantly inhibited after pretreatment with ondansetron (5-HT(3) antagonist) or RS 39604 (5-HT(4) antagonist) (1-5 mg/kg). The GIT speed was increased after CO and 5-HTP administration. 5-HT(3-4) antagonists decreased GIT after 5-HTP-treatment but not after CO-treatment. Our results show that 5-HT(3) and 5-HT(4) receptors are involved in 5-HTP-induced diarrhea. This may be the reason why 5-HT(3-4) antagonists could be useful in the treatment of carcinoid syndrome diarrhea. 5-HT(3-4) antagonists were not effective in the modifications of GIT; nevertheless, they could be useful in the treatment of inflammatory bowel diseases because some symptoms as abdominal pain, discomfort or abnormal bowel function are modulated via 5-HT(3).

  17. Bivalent Ligands for the Serotonin 5-HT3 Receptor

    PubMed Central

    2011-01-01

    The serotonin 5-HT3 receptor is a ligand-gated ion channel, which by virtue of its pentameric architecture, can be considered to be an intriguing example of intrinsically multivalent biological receptors. This paper describes a general design approach to the study of multivalency in this multimeric ion channel. Bivalent ligands for 5-HT3 receptor have been designed by linking an arylpiperazine moiety to probes showing different functional features. Both homobivalent and heterobivalent ligands have shown 5-HT3 receptor affinity in the nanomolar range, providing evidence for the viability of our design approach. Moreover, the high affinity shown by homobivalent ligands suggests that bivalency is a promising approach in 5-HT3 receptor modulation and provides the rational basis for applying the concepts of multivalency to the study of 5-HT3 receptor function. PMID:24900351

  18. Synthesis and characterization of photoaffinity probes that target the 5-HT3 receptor.

    PubMed

    Jack, Thomas; Ruepp, Marc-David; Thompson, Andrew J; Mühlemann, Oliver; Lochner, Martin

    2014-01-01

    The 5-HT3 receptor is one of several ion channels responsible for the transmission of nerve impulses in the peripheral and central nervous systems. Until now, it has been difficult to characterize transmembrane receptors with classical structural biology approaches like X-ray crystallography. The use of photoaffinity probes is an alternative approach to identify regions in the protein where small molecules bind. To this end, we present two photoaffinity probes based on granisetron, a well known antagonist of the 5-HT3 receptor. These new probes show nanomolar binding affinity for the orthosteric binding site. In addition, we investigated their reactivity using irradiation experiments.

  19. Seizure susceptibility alteration through 5-HT(3) receptor: modulation by nitric oxide.

    PubMed

    Gholipour, Taha; Ghasemi, Mehdi; Riazi, Kiarash; Ghaffarpour, Majid; Dehpour, Ahmad Reza

    2010-01-01

    There is some evidence that epileptic seizures could be induced or increased by 5-hydroxytryptamine (5-HT) attenuation, while augmentation of serotonin functions within the brain (e.g. by SSRIs) has been reported to be anticonvulsant. This study was performed to determine the effect of selective 5-HT(3) channel/receptor antagonist granisetron and agonist SR57227 hydrochloride on the pentylenetetrazole (PTZ)-induced seizure threshold in mice. The possible interaction of this effect with nitrergic system was also examined using the nitric oxide (NO) synthase inhibitor N(G)-nitro-l-arginine methyl ester (l-NAME) and the NO precursor l-arginine. SR57227 (10mg/kg, i.p.) significantly increased the seizure threshold compared to control group, while high dose granisetron (10mg/kg, i.p.) proved proconvulsant. Co-administration of sub-effective doses of the 5-HT(3) agonist with l-NAME (5 and 60mg/kg, i.p., respectively) exerted a significant anticonvulsive effect, while sub-effective doses of granisetron (3mg/kg) was observed to have a proconvulsive action with the addition of l-arginine (75mg/kg, i.p.). Our data demonstrate that enhancement of 5-HT(3) receptor function results in as anticonvulsant effect in the PTZ-induced seizure model, and that selective antagonism at the 5-HT(3) receptor yields proconvulsive effects. Furthermore, the NO system may play a role in 5-HT(3) receptor function.

  20. 5-HT3 receptors as important mediators of nausea and vomiting due to chemotherapy.

    PubMed

    Navari, Rudolph M

    2015-10-01

    Chemotherapy-induced nausea and vomiting (CINV) is associated with a significant deterioration in quality of life. The emetogenicity of the chemotherapeutic agents, repeated chemotherapy cycles, and patient risk factors significantly influence CINV. The use of a combination of a 5-hydroxytryptamine-3 (5-HT3) receptor antagonist, dexamethasone, and a neurokinin-1 (NK-1) receptor antagonist has significantly improved the control of acute and delayed emesis in single-day chemotherapy. The first generation 5-HT3 receptor antagonists have been very effective in the control of chemotherapy induced emesis in the first 24 h postchemotherapy (acute emesis), but have not been as effective against delayed emesis (24-120 h postchemotherapy). Palonosetron, a second generation 5-HT3 receptor antagonist with a different half-life, a different binding capacity, and a different mechanism of action than the first generation 5-HT3 receptor antagonists appears to be the most effective agent in its class. Despite the control of emesis, nausea has not been well controlled by current agents. Olanzapine, a FDA approved antipsychotic that blocks multiple neurotransmitters: dopamine at D1, D2, D3, D4 brain receptors, serotonin at 5-HT2a, 5-HT2c, 5-HT3, 5-HT6 receptors, catecholamines at alpha1 adrenergic receptors, acetylcholine at muscarinic receptors, and histamine at H1 receptors, has emerged in recent trials as an effective preventative agent for chemotherapy-induced emesis and nausea, as well as a very effective agent for the treatment of breakthrough emesis and nausea. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

  1. The serotonin 5-HT3 receptor: a novel neurodevelopmental target.

    PubMed

    Engel, Mareen; Smidt, Marten P; van Hooft, Johannes A

    2013-01-01

    Serotonin (5-hydroxytryptamine, 5-HT), next to being an important neurotransmitter, recently gained attention as a key-regulator of pre- and postnatal development in the mammalian central nervous system (CNS). Several receptors for 5-HT are expressed in the developing brain including a ligand-gated ion channel, the 5-HT3 receptor. Over the past years, evidence has been accumulating that 5-HT3 receptors are involved in the regulation of neurodevelopment by serotonin. Here, we review the spatial and temporal expression patterns of 5-HT3 receptors in the pre- and early postnatal rodent brain and its functional implications. First, 5-HT3 receptors are expressed on GABAergic interneurons in neocortex and limbic structures derived from the caudal ganglionic eminence. Mature inhibitory GABAergic interneurons fine-tune neuronal excitability and thus are crucial for the physiological function of the brain. Second, 5-HT3 receptors are expressed on specific glutamatergic neurons, Cajal-Retzius cells in the cortex and granule cells in the cerebellum, where they regulate morphology, positioning, and connectivity of the local microcircuitry. Taken together, the 5-HT3 receptor emerges as a potential key-regulator of network formation and function in the CNS, which could have a major impact on our understanding of neurodevelopmental disorders in which 5-HT plays a role.

  2. Toward Biophysical Probes for the 5-HT3 Receptor: Structure−Activity Relationship Study of Granisetron Derivatives

    PubMed Central

    2010-01-01

    This report describes the synthesis and biological characterization of novel granisetron derivatives that are antagonists of the human serotonin (5-HT3A) receptor. Some of these substituted granisetron derivatives showed low nanomolar binding affinity and allowed the identification of positions on the granisetron core that might be used as attachment points for biophysical tags. A BODIPY fluorophore was appended to one such position and specifically bound to 5-HT3A receptors in mammalian cells. PMID:20146481

  3. Protective effects of a novel 5-HT3 receptor antagonist, N-n-butyl-3-methoxy quinoxaline-2-carboxamide (6o) against chronic unpredictable mild stress-induced behavioral changes and biochemical alterations.

    PubMed

    Bhatt, Shvetank; Mahesh, Radhakrishnan; Jindal, Ankur; Devadoss, Thangaraj

    2014-07-01

    Stimulation of high oxidative stress in the brain is considered as an important factor for neurotoxicity towards the pathophysiology of chronic stress-induced depression disorder. In the present research, a potential 5-HT₃ receptor antagonist N-n-butyl-3-methoxy quinoxaline-2-carboxamide (6o) having good Log P (2.60) and pA₂ (7.7) values was examined for its effect on the behavioral and biochemical changes induced by the chronic unpredictable mild stress (CUMS) model. In the current investigation mice were introduced to different stress procedures daily for a period of 28 days to induce a depressive-like behavior. The results show that CUMS caused a depression-like behavior in mice, as indicated by the significant decrease in sucrose consumption and locomotor activity and increase in immobility in the forced swim test (FST). Moreover, it was found that oxidative stress markers such as lipid peroxide and nitrite levels were significantly increased, whereas, antioxidant enzymes such as glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) levels were decreased in the brain tissue of CUMS-subjected mice. "Compound 6o" (1 and 2 mg/kg, p.o.) and fluoxetine treatment (20 mg/kg, p.o.) for a period of 21 days altered the CUMS-induced behavioral (increased immobility period, reduced sucrose preference and decreased locomotor activity) and biochemical (increased lipid peroxide, increased brain nitrite; decreased GSH, SOD and CAT levels) alterations. Moreover normal mice treated with "compound 6o" (2 mg/kg, p.o.) showed a significant decrease in the duration of immobility in FST as compared to normal vehicle treated mice. In conclusion, "compound 6o" produced antidepressant-like effects in behavioral despair paradigm in chronically stressed mice by restoring antioxidant enzyme activity.

  4. Shuyu Capsules Relieve Premenstrual Syndrome Depression by Reducing 5-HT3AR and 5-HT3BR Expression in the Rat Brain

    PubMed Central

    Li, Fang; Feng, Jizhen; Gao, Dongmei; Wang, Jieqiong; Song, Chunhong; Wei, Sheng

    2016-01-01

    The effects of the Shuyu capsule on 5-HT3AR and 5-HT3BR expression in a rat model of premenstrual syndrome (PMS) depression and on 5-HT3AR and 5-HT3BR expression and hippocampal neuron 5-HT3 channel current were investigated, to elucidate its mechanism of action against PMS depression. PMS depression model rats were divided into depression and Shuyu- and fluoxetine-treated groups, which were compared to control rats for frontal lobe and hippocampal 5-HT3AR and 5-HT3BR expression and behavior. The depressed model rats displayed symptoms of depression, which were reduced in treated and normal control rats. Frontal lobe and hippocampal 5-HT3AR and 5-HT3BR levels were significantly higher in the model versus the control group and were significantly lower in the Shuyu group. As compared to control rats, the 5-HT3R channel current in the model group was significantly higher; the 5-HT3R channel current in hippocampal neurons treated with serum from Shuyu group rats was significantly lower than that in those treated with model group serum. Thus, PMS depression may be related to 5-HT3AR and 5-HT3BR expression and increased 5-HT3 channel current. Shuyu capsules rectified abnormal 5-HT3AR and 5-HT3BR expression and 5-HT3 channel current changes in a rat model; this finding may provide insight into treating PMS depression. PMID:27725889

  5. The multi-functional drug tropisetron binds APP and normalizes cognition in a murine Alzheimer's model.

    PubMed

    Spilman, Patricia; Descamps, Olivier; Gorostiza, Olivia; Peters-Libeu, Clare; Poksay, Karen S; Matalis, Alexander; Campagna, Jesus; Patent, Alexander; Rao, Rammohan; John, Varghese; Bredesen, Dale E

    2014-03-10

    Tropisetron was identified in a screen for candidates that increase the ratio of the trophic, neurite-extending peptide sAPPα to the anti-trophic, neurite-retractive peptide Aβ, thus reversing this imbalance in Alzheimer's disease (AD). We describe here a hierarchical screening approach to identify such drug candidates, moving from cell lines to primary mouse hippocampal neuronal cultures to in vivo studies. By screening a clinical compound library in the primary assay using CHO-7W cells stably transfected with human APPwt, we identified tropisetron as a candidate that consistently increased sAPPα. Secondary assay testing in neuronal cultures from J20 (PDAPP, huAPP(Swe/Ind)) mice showed that tropisetron consistently increased the sAPPα/Aβ 1-42 ratio. In in vivo studies in J20 mice, tropisetron improved the sAPPα/Aβ ratio along with spatial and working memory in mice, and was effective both during the symptomatic, pre-plaque phase (5-6 months) and in the late plaque phase (14 months). This ameliorative effect occurred at a dose of 0.5mg/kg/d (mkd), translating to a human-equivalent dose of 5mg/day, the current dose for treatment of postoperative nausea and vomiting (PONV). Although tropisetron is a 5-HT3 receptor antagonist and an α7nAChR partial agonist, we found that it also binds to the ectodomain of APP. Direct comparison of tropisetron to the current AD therapeutics memantine (Namenda) and donepezil (Aricept), using similar doses for each, revealed that tropisetron induced greater improvements in memory and the sAPPα/Aβ1-42 ratio. The improvements observed with tropisetron in the J20 AD mouse model, and its known safety profile, suggest that it may be suitable for transition to human trials as a candidate therapeutic for mild cognitive impairment (MCI) and AD, and therefore it has been approved for testing in clinical trials beginning in 2014. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Involvement of 5-HT3 receptors in the action of vortioxetine in rat brain: Focus on glutamatergic and GABAergic neurotransmission.

    PubMed

    Riga, Maurizio S; Sánchez, Connie; Celada, Pau; Artigas, Francesc

    2016-09-01

    The antidepressant vortioxetine is a 5-HT3-R, 5-HT7-R and 5-HT1D-R antagonist, 5-HT1B-R partial agonist, 5-HT1A-R agonist, and serotonin (5-HT) transporter (SERT) inhibitor. Vortioxetine occupies all targets at high therapeutic doses and only SERT and 5-HT3-R at low doses. Vortioxetine increases extracellular monoamine concentrations in rat forebrain more than selective serotonin reuptake inhibitors (SSRI) and shows pro-cognitive activity in preclinical models. Given its high affinity for 5-HT3-R (Ki = 3.7 nM), selectively expressed in GABA interneurons, we hypothesized that vortioxetine may disinhibit glutamatergic and monoaminergic neurotransmission following 5-HT3-R blockade. Here we assessed vortioxetine effect on pyramidal neuron activity and extracellular 5-HT concentration using in vivo extracellular recordings of rat medial prefrontal cortex (mPFC) pyramidal neurons and microdialysis in mPFC and ventral hippocampus (vHPC). Vortioxetine, but not escitalopram, increased pyramidal neuron discharge in mPFC. This effect was prevented by SR57227A (5-HT3-R agonist) and was mimicked by ondansetron (5-HT3-R antagonist) and by escitalopram/ondansetron combinations. In microdialysis experiments, ondansetron augmented the 5-HT-enhancing effect of escitalopram in mPFC and vHPC. Local ondansetron in vHPC augmented escitalopram effect, indicating the participation of intrinsic mechanisms. Since 5-HT neurons express GABAB receptors, we examined their putative involvement in controlling 5-HT release after 5-HT3-R blockade. Co-perfusion of baclofen (but not muscimol) reversed the increased 5-HT levels produced by vortioxetine and escitalopram/ondansetron combinations in vHPC. The present results suggest that vortioxetine increases glutamatergic and serotonergic neurotransmission in rat forebrain by blocking 5-HT3 receptors in GABA interneurons.

  7. Comparative receptor mapping of serotoninergic 5-HT3 and 5-HT4 binding sites*

    NASA Astrophysics Data System (ADS)

    López-Rodríguez, María L.; Morcillo, María José; Benhamú, Bellinda; Rosado, María Luisa

    1997-11-01

    The clinical use of currently available drugs acting at the5-HT4 receptor has been hampered by their lack of selectivityover 5-HT3 binding sites. For this reason, there is considerableinterest in the medicinal chemistry of these serotonin receptor subtypes, andsignificant effort has been made towards the discovery of potent and selectiveligands. Computer-aided conformational analysis was used to characterizeserotoninergic 5-HT3 and 5-HT4 receptorrecognition. On the basis of the generally accepted model of the5-HT3 antagonist pharmacophore, we have performed a receptormapping of this receptor binding site, following the active analog approach(AAA) defined by Marshall. The receptor excluded volume was calculated as theunion of the van der Waals density maps of nine active ligands(pKi ≥ 8.9), superimposed in pharmacophoric conformations.Six inactive analogs (pKi < 7.0) were subsequently used todefine the essential volume, which in its turn can be used to define theregions of steric intolerance of the 5-HT3 receptor. Five activeligands (pKi ≥ 9.3) at 5-HT4 receptors wereused to construct an antagonist pharmacophore for this receptor, and todetermine its excluded volume by superimposition of pharmacophoricconformations. The volume defined by the superimposition of five inactive5-HT4 receptor analogs that possess the pharmacophoric elements(pKi ≤ 6.6) did not exceed the excluded volume calculated forthis receptor. In this case, the inactivity may be due to the lack of positiveinteraction of the amino moiety with a hypothetical hydrophobic pocket, whichwould interact with the voluminous substituents of the basic nitrogen ofactive ligands. The difference between the excluded volumes of both receptorshas confirmed that the main difference is indeed in the basic moiety. Thus,the 5-HT3 receptor can only accommodate small substituents inthe position of the nitrogen atom, whereas the 5-HT4 receptorrequires more voluminous groups. Also, the basic nitrogen is located at ca

  8. Human-derived gut microbiota modulates colonic secretion in mice by regulating 5-HT3 receptor expression via acetate production.

    PubMed

    Bhattarai, Yogesh; Schmidt, Bradley A; Linden, David R; Larson, Eric D; Grover, Madhusudan; Beyder, Arthur; Farrugia, Gianrico; Kashyap, Purna C

    2017-07-01

    Serotonin [5-hydroxytryptamine (5-HT)], an important neurotransmitter and a paracrine messenger in the gastrointestinal tract, regulates intestinal secretion by its action primarily on 5-HT3 and 5-HT4 receptors. Recent studies highlight the role of gut microbiota in 5-HT biosynthesis. In this study, we determine whether human-derived gut microbiota affects host secretory response to 5-HT and 5-HT receptor expression. We used proximal colonic mucosa-submucosa preparation from age-matched Swiss Webster germ-free (GF) and humanized (HM; ex-GF colonized with human gut microbiota) mice. 5-HT evoked a significantly greater increase in short-circuit current (ΔIsc) in GF compared with HM mice. Additionally, 5-HT3 receptor mRNA and protein expression was significantly higher in GF compared with HM mice. Ondansetron, a 5-HT3 receptor antagonist, inhibited 5-HT-evoked ΔIsc in GF mice but not in HM mice. Furthermore, a 5-HT3 receptor-selective agonist, 2-methyl-5-hydroxytryptamine hydrochloride, evoked a significantly higher ΔIsc in GF compared with HM mice. Immunohistochemistry in 5-HT3A-green fluorescent protein mice localized 5-HT3 receptor expression to enterochromaffin cells in addition to nerve fibers. The significant difference in 5-HT-evoked ΔIsc between GF and HM mice persisted in the presence of tetrodotoxin (TTX) but was lost after ondansetron application in the presence of TTX. Application of acetate (10 mM) significantly lowered 5-HT3 receptor mRNA in GF mouse colonoids. We conclude that host secretory response to 5-HT may be modulated by gut microbiota regulation of 5-HT3 receptor expression via acetate production. Epithelial 5-HT3 receptor may function as a mediator of gut microbiota-driven change in intestinal secretion.NEW & NOTEWORTHY We found that gut microbiota alters serotonin (5-HT)-evoked intestinal secretion in a 5-HT3 receptor-dependent mechanism and gut microbiota metabolite acetate alters 5-HT3 receptor expression in colonoids.View this article

  9. From mouse to man: the 5-HT3 receptor modulates physical dependence on opioid narcotics

    PubMed Central

    Chu, Larry F.; Liang, De-Yong; Li, Xiangqi; Sahbaie, Peyman; D'Arcy, Nicole; Liao, Guochun; Peltz, Gary; Clark, J. David

    2009-01-01

    Objectives Addiction to opioid narcotics represents a major public health challenge. Animal models of one component of addiction, physical dependence, show this trait to be highly heritable. The analysis of opioid dependence using contemporary in-silico techniques offers an approach to discover novel treatments for dependence and addiction. Methods In these experiments, opioid withdrawal behavior in 18 inbred strains of mice was assessed. Mice were treated for 4 days with escalating doses of morphine before the administration of naloxone allowing the quantification of opioid dependence. After haplotypic analysis, experiments were designed to evaluate the top gene candidate as a modulator of physical dependence. Behavioral studies as well as measurements of gene expression on the mRNA and protein levels were completed. Finally, a human model of opioid dependence was used to quantify the effects of the 5-HT3 antagonist ondansetron on signs and symptoms of withdrawal. Results The Htr3a gene corresponding to the 5-HT3 receptor emerged as the leading candidate. Pharmacological studies using the selective 5-HT3 antagonist ondansetron supported the link in mice. Morphine strongly regulated the expression of the Htr3a gene in various central nervous system regions including the amygdala, dorsal raphe, and periaqueductal gray nuclei, which have been linked to opioid dependence in previous studies. Using an acute morphine administration model, the role of 5-HT3 in controlling the objective signs of withdrawal in humans was confirmed. Conclusion These studies show the power of in-silico genetic mapping, and reveal a novel target for treating an important component of opioid addiction. PMID:19214139

  10. From mouse to man: the 5-HT3 receptor modulates physical dependence on opioid narcotics.

    PubMed

    Chu, Larry F; Liang, De-Yong; Li, Xiangqi; Sahbaie, Peyman; D'arcy, Nicole; Liao, Guochun; Peltz, Gary; David Clark, J

    2009-03-01

    Addiction to opioid narcotics represents a major public health challenge. Animal models of one component of addiction, physical dependence, show this trait to be highly heritable. The analysis of opioid dependence using contemporary in-silico techniques offers an approach to discover novel treatments for dependence and addiction. In these experiments, opioid withdrawal behavior in 18 inbred strains of mice was assessed. Mice were treated for 4 days with escalating doses of morphine before the administration of naloxone allowing the quantification of opioid dependence. After haplotypic analysis, experiments were designed to evaluate the top gene candidate as a modulator of physical dependence. Behavioral studies as well as measurements of gene expression on the mRNA and protein levels were completed. Finally, a human model of opioid dependence was used to quantify the effects of the 5-HT3 antagonist ondansetron on signs and symptoms of withdrawal. The Htr3a gene corresponding to the 5-HT3 receptor emerged as the leading candidate. Pharmacological studies using the selective 5-HT3 antagonist ondansetron supported the link in mice. Morphine strongly regulated the expression of the Htr3a gene in various central nervous system regions including the amygdala, dorsal raphe, and periaqueductal gray nuclei, which have been linked to opioid dependence in previous studies. Using an acute morphine administration model, the role of 5-HT3 in controlling the objective signs of withdrawal in humans was confirmed. These studies show the power of in-silico genetic mapping, and reveal a novel target for treating an important component of opioid addiction.

  11. Spinal 5-HT3AR contributes to BmK I-induced inflammatory pain in rats.

    PubMed

    Fu, Jin; Jiao, Yun-Lu; Li, Zheng-Wei; Ji, Yong-Hua

    2015-06-25

    Subcutaneous injection of BmK I could be adopted to well establish a novel pain model. Moreover, 5-hydroxytryptamine (serotonin, 5-HT) receptor is involved in regulating animal pain-related behaviors. However, the underlying mechanism of 5-HT3R on BmK I-induced pain remains unclear. Animal behavioral testing, RT-PCR and Western blotting were used to yield the following results: first, intraplantar (i.pl.) injection of BmK I (10 μg) induced elevated mRNA and protein levels of 5-HT3AR in bilateral L4-L5 spinal cord; Second, intrathecal (i.t.) injection of ondansetron (a specific antagonist of 5-HT3AR) reduced spontaneous pain responses, attenuated unilateral thermal and bilateral mechanical hypersensitivity elicited by BmK I; Microglia could be activated by BmK I (i.pl.) in both sides of L4-L5 spinal cord, and this effect was reversed by intrathecal pre-treatment with 5-HT3AR antagonist. Meanwhile, the 5-HT3AR in L4-L5 spinal cord was almost co-localized with NeuN (a marker of nerve cell), but not co-expressed with Iba-1 (a marker of microglia). Finally, the expression level of CX3CL1 and CX3CR1 was reduced by intrathecal pre-treatment with ondansetron. Our results indicate that both 5-HT3AR signaling pathway and microglia are activated in the process of induction and maintenance of BmK I-induced pain nociception. Meanwhile, our results suggest that the neuronal 5-HT3AR may communicate with microglia indirectly via CX3CL1 which is involved in regulating the BmK I-induced hyperalgesia and sensitization.

  12. Role of 5-HT3 Receptor on Food Intake in Fed and Fasted Mice

    PubMed Central

    Li, Bingjin; Shao, Dongyuan; Luo, Yungang; Wang, Pu; Liu, Changhong; Zhang, Xingyi; Cui, Ranji

    2015-01-01

    Background Many studies have shown that 5-hydroxytryptamine (5-HT) receptor subtypes are involved in the regulation of feeding behavior. However, the relative contribution of 5-HT3 receptor remains unclear. The present study was aimed to investigate the role of 5-HT3 receptor in control of feeding behavior in fed and fasted mice. Methodology/Principal Findings Food intake and expression of c-Fos, tyrosine hydroxylase (TH), proopiomelanocortin (POMC) and 5-HT in the brain were examined after acute treatment with 5-HT3 receptor agonist SR-57227 alone or in combination with 5-HT3 receptor antagonist ondansetron. Food intake was significantly inhibited within 3 h after acute treatment with SR 57227 in fasted mice but not fed mice, and this inhibition was blocked by ondansetron. Immunohistochemical study revealed that fasting-induced c-Fos expression was further enhanced by SR 57227 in the brainstem and the hypothalamus, and this enhancement was also blocked by ondansetron. Furthermore, the fasting-induced downregulation of POMC expression in the hypothalamus and the TH expression in the brain stem was blocked by SR 57227 in the fasted mice, and this effect of SR 57227 was also antagonized by ondansetron. Conclusion/Significance Taken together, our findings suggest that the effect of SR 57227 on the control of feeding behavior in fasted mice may be, at least partially, related to the c-Fos expression in hypothalamus and brain stem, as well as POMC system in the hypothalamus and the TH system in the brain stem. PMID:25789930

  13. Partial Agonism of 5-HT3 Receptors: A Novel Approach to the Symptomatic Treatment of IBS-D

    PubMed Central

    2012-01-01

    Irritable bowel syndrome (IBS) is a functional bowel disorder characterized by abdominal pain, discomfort, and altered bowel habits, which have a significant impact on quality of life for approximately 10–20% of the population. IBS can be divided into three main types IBS-D (diarrhea predominant), IBS-C (constipation predominant), and mixed or alternating IBS. 5-HT3 receptor antagonism has proved to be an efficacious treatment option for IBS-D. For example, alosetron displays efficacy in the treatment of multiple symptoms, including abdominal pain, discomfort, urgency, stool frequency and consistency. However, significant constipation occurred in approximately 25% of patients, leading to withdrawal of up to 10% of patients in clinical trials. Targeting compounds with partial agonist activity at the 5-HT3 receptor represents a mechanistic departure from the classic 5-HT3 receptor antagonist approach and should result in agents that are applicable to a broader array of IBS patient populations. Attenuation of the activity of the ion channel without completely abolishing its function may control or normalize bowel function without leading to a total block associated with severe constipation. We have identified a new class of selective, orally active 5-HT3 receptor ligands with high 5-HT3 receptor affinity and low partial agonist activity currently in preclinical development that should offer a significant advantage over existing therapies. PMID:23342199

  14. Tropisetron sensitizes α7 containing nicotinic receptors to low levels of acetylcholine in vitro and improves memory-related task performance in young and aged animals.

    PubMed

    Callahan, Patrick M; Bertrand, Daniel; Bertrand, Sonia; Plagenhoef, Marc R; Terry, Alvin V

    2017-03-01

    Tropisetron, a 5-HT3 receptor antagonist commonly prescribed for chemotherapy-induced nausea and vomiting also exhibits high affinity, partial agonist activity at α7 nicotinic acetylcholine receptors (α7 nAChRs). α7 nAChRs are considered viable therapeutic targets for neuropsychiatric disorders such as Alzheimer's disease (AD). Here we further explored the nAChR pharmacology of tropisetron to include the homomeric α7 nAChR and recently characterized heteromeric α7β2 nAChR (1:10 ratio) and we evaluated its cognitive effects in young and aged animals. Electrophysiological studies on human nAChRs expressed in Xenopus oocytes confirmed the partial agonist activity of tropisetron at α7 nAChRs (EC50 ∼2.4 μM) with a similar effect at α7β2 nAChRs (EC50 ∼1.5 μM). Moreover, currents evoked by irregular pulses of acetylcholine (40 μM) at α7 and α7β2 nAChRs were enhanced during sustained exposure to low concentrations of tropisetron (10 and 30 nM) indicative of a "priming" or co-agonist effect. Tropisetron (0.1-10 mg/kg) improved novel object recognition performance in young Sprague-Dawley rats and in aged Fischer rats. In aged male and female rhesus monkeys, tropisetron (0.03-1 mg/kg) produced a 17% increase from baseline levels in delayed match to sample long delay accuracy while combination of non-effective doses of donepezil (0.1 mg/kg) and tropisetron (0.03 and 0.1 mg/kg) produced a 24% change in accuracy. Collectively, these animal experiments indicate that tropisetron enhances cognition and has the ability to improve the effective dose range of currently prescribed AD therapy (donepezil). Moreover, these effects may be explained by tropisetron's ability to sensitize α7 containing nAChRs to low levels of acetylcholine.

  15. Molecular properties of psychopharmacological drugs determining non-competitive inhibition of 5-HT3A receptors.

    PubMed

    Kornhuber, Johannes; Terfloth, Lothar; Bleich, Stefan; Wiltfang, Jens; Rupprecht, Rainer

    2009-06-01

    We developed a structure-property-activity relationship (SPAR)-model for psychopharmacological drugs acting as non-competitive 5-HT(3A) receptor antagonists by using a decision-tree learner provided by the RapidMiner machine learning tool. A single molecular descriptor, namely the molecular dipole moment per molecular weight (mu/MW), predicts whether or not a substance non-competitively antagonizes 5-HT-induced Na(+) currents. A low mu/MW is compatible with drug-cumulation in apolar lipid rafts. This study confirms that size-intensive descriptors allow the development of compact SPAR models.

  16. Influence of sodium substitutes on 5-HT-mediated effects at mouse 5-HT3 receptors

    PubMed Central

    Barann, M; Schmidt, K; Göthert, M; Urban, B W; Bönisch, H

    2004-01-01

    The influence of sodium ion substitutes on the 5-hydroxytryptamine (5-HT)-induced flux of the organic cation [14C]guanidinium through the ion channel of the mouse 5-HT3 receptor and on the competition of 5-HT with the selective 5-HT3 receptor antagonist [3H]GR 65630 was studied, unless stated otherwise, in mouse neuroblastoma N1E-115 cells. Under physiological conditions (135 mM sodium), 5-HT induced a concentration-dependent [14C]guanidinium influx with an EC50 (1.3 μM) similar to that in electrophysiological studies. The stepwise replacement of sodium by increasing concentrations of the organic cation hydroxyethyl trimethylammonium (choline) concentration dependently caused both a rightward shift of the 5-HT concentration–response curve and an increase in the maximum effect of 5-HT. Complete replacement of sodium resulted in a 34-fold lower potency of 5-HT and an almost two times higher maximal response. A low potency of 5-HT in choline buffer was also observed in other 5-HT3 receptor-expressing rodent cell lines (NG 108-15 or NCB 20). Replacement of Na+ by Li+ left the potency and maximal effects of 5-HT almost unchanged. Replacement by tris (hydroxymethyl) methylamine (Tris), tetramethylammonium (TMA) or N-methyl-D-glucamine (NMDG) caused an increase in maximal response to 5-HT similar to that caused by choline. The potency of 5-HT was only slightly reduced by Tris, to a high degree decreased by TMA (comparable to the decrease by choline), but not influenced by NMDG. The potency of 5-HT in inhibiting [3H]GR65630 binding to intact cells was 35-fold lower when sodium was completely replaced by choline, but remained unchanged after replacement by NMDG. The results are compatible with the suggestion that choline competes with 5-HT for the 5-HT3 receptor; the increase in maximal response may be partly due to a choline-mediated delay of the 5-HT-induced desensitization. For studies of 5-HT-evoked [14C]guanidinium flux through 5-HT3 receptor channels, NMDG appears

  17. Effects of serotonin on acid secretion in isolated rat stomach: the role of 5-HT3 receptors.

    PubMed

    Lai, Yung-Chih; Ho, Yih; Huang, Kai-Han; Tsai, Li Hsueh

    2009-11-30

    Serotonin (5-hydroxytryptamin; 5-HT) content has been measured using high-performance liquid chromatography with electrochemical detection (HPLC-ECD). The distributions of 5-HT-containing cells and 5-HT3 receptors have been determined with specific antibodies against 5-HT and 5-HT3 receptors, respectively. The effect of serotonin on acid secretion has been studied using an isolated rat stomach model. It has been shown that 5-HT concentrations in the fundus, mucosal layers of the corpus, remaining layer of the corpus and antrum are approximately 152, 498, 1494 and 972 nmol/mg protein, respectively. The distribution of 5-HT-containing cells is concentrated in the enteric plexus and enterochromaffin (EC) cells in the deep mucosal layer. Immunoreactivity to 5-HT3 receptors is localized in numerous neurons of the myenteric and submucosal plexus and concentrated in the neuronal plasma membrane, submucosa, endocrine cells and lamina propria. In the present study, the effect of 5-HT on gastric acid secretion was investigated on an everted preparation of isolated rat stomach. 5-HT at 1-100 microM reduced acid secretion stimulated by oxotremorine while 10 microM 5-HT did not modify the basal secretion of gastric acid. We further showed that 10 microM 5-HT reduced acid secretion and pepsin output stimulated by oxotremorine, histamine and pentagastrin; among the 5-HT receptors agonists tested, 2-methyl-5-HT (1-10 microM), a 5-HT3 receptor agonist, inhibited oxotremorine-, histamine- and pentagastrin-stimulated acid secretions, and this inhibitory effect was blocked by 1 microM MDL 72222, a specific 5-HT3 receptor antagonist. These results suggest that 5-HT is released from serotoninergic neurons, their processes and EC cells. The effect of 5-HT mediated by 5-HT3 receptors involves distinct neuronal and non-neuronal pathways which modulate gastric acid secretion.

  18. Structure-activity relationships of quinoxaline-based 5-HT3A and 5-HT3AB receptor-selective ligands.

    PubMed

    Thompson, Andrew J; Verheij, Mark H P; van Muijlwijk-Koezen, Jacqueline E; Lummis, Sarah C R; Leurs, Rob; de Esch, Iwan J P

    2013-06-01

    Until recently, discriminating between homomeric 5-HT3A and heteromeric 5-HT3AB receptors was only possible with ligands that bind in the receptor pore. This study describes the first series of ligands that can discriminate between these receptor types at the level of the orthosteric binding site. During a recent fragment screen, 2-chloro-3-(4-methylpiperazin-1-yl)quinoxaline (VUF10166) was identified as a ligand that displays an 83-fold difference in [(3)H]granisetron binding affinity between 5-HT3A and 5-HT3AB receptors. Fragment hit exploration, initiated from VUF10166 and 3-(4-methylpiperazin-1-yl)quinoxalin-2-ol, resulted in a series of compounds with higher affinity at either 5-HT3A or 5-HT3AB receptors. These ligands reveal that a single atom is sufficient to change the selectivity profile of a compound. At the extremes of the new compounds were 2-amino-3-(4-methylpiperazin-1-yl)quinoxaline, which showed 11-fold selectivity for the 5-HT3A receptor, and 2-(4-methylpiperazin-1-yl)quinoxaline, which showed an 8.3-fold selectivity for the 5-HT3AB receptor. These compounds represent novel molecular tools for studying 5-HT3 receptor subtypes and could help elucidate their physiological roles.

  19. Epigenetic and pharmacological regulation of 5HT3 receptors controls compulsive ethanol seeking in mice.

    PubMed

    Barker, Jacqueline M; Zhang, Huiping; Villafane, J Joshua; Wang, Tiffany L; Torregrossa, Mary M; Taylor, Jane R

    2014-03-01

    Factors underlying individual vulnerability to develop alcoholism are largely unknown. In humans, the risk for alcoholism is associated with elevated cue reactivity. Recent evidence suggests that in animal models, reactivity to reward-paired cues is predictive of addictive behaviors. To model cue reactivity in mice, we used a Pavlovian approach (PA) paradigm in which mice were trained to associate a cue with delivery of a food reinforcer. We then investigated the relationship between PA status with habitual and compulsive-like ethanol seeking. After training mice to respond for 10% ethanol, habitual behavior was investigated using both an outcome devaluation paradigm, in which ethanol was devalued via association with lithium chloride-induced malaise, and a contingency degradation paradigm in which the relationship between action and outcome was disrupted. Compulsive-like behavior was investigated in a modified conditioned place preference paradigm in which footshock was paired with the reward-paired chamber. PA was found to be predictive of habitual and compulsive-like ethanol seeking. Additionally, innate risk status was related to epigenetic changes in the gene encoding the requisite subunit of the 5HT3 receptor, Htr3a, as well as 5HT3A protein expression in the amygdala. We then used pharmacological tools to demonstrate that risk status determines the ability of a 5HT3 antagonist to reduce compulsive ethanol seeking. These data indicate that risk status can be identified prior to any alcohol exposure by assessment of cue reactivity, and further that this endophenotype may be predictive of response to pharmacological treatment for components of alcoholism.

  20. Epigenetic and pharmacological regulation of 5HT3 receptors controls compulsive ethanol seeking

    PubMed Central

    Barker, Jacqueline M; Zhang, Huiping; Villafane, J Joshua; Wang, Tiffany L; Torregrossa, Mary M; Taylor, Jane R

    2014-01-01

    Factors underlying individual vulnerability to develop alcoholism are largely unknown. In humans, risk for alcoholism is associated with elevated cue reactivity. Recent evidence suggests that in animal models, reactivity to reward-paired cues is predictive of addictive behaviors. To model cue reactivity in mice, we used a Pavlovian approach (PA) paradigm in which mice were trained to associate a cue with delivery of a food reinforcer. We then investigated the relationship between PA status with habitual and compulsive-like ethanol seeking. After training mice to respond for 10% ethanol, habitual behavior was investigated using both an outcome devaluation paradigm, in which ethanol was devalued via association with lithium chloride induced malaise, and a contingency degradation paradigm in which the relationship between action and outcome was disrupted. Compulsive-like behavior was investigated in a modified conditioned place preference paradigm in which footshock was paired with the reward-paired chamber. We saw that high PA was predictive of habitual and compulsive-like ethanol seeking. Additionally, innate risk status was related to epigenetic changes in the gene encoding the requisite subunit of the 5HT3 receptor, Htr3a, as well as 5HT3A protein expression in the amygdala. We then used pharmacological tools to demonstrate that risk status determines the ability of a 5HT3 antagonist to reduce compulsive ethanol seeking. These data indicate that risk status can be identified prior to any alcohol exposure by assessment of cue reactivity, and further, that this endophenotype may be predictive of response to pharmacological treatment for components of alcoholism. PMID:24772465

  1. Anti-inflammatory effect of ondansetron through 5-HT3 receptors on TNBS-induced colitis in rat

    PubMed Central

    Motavallian-Naeini, Azadeh; Minaiyan, Mohsen; Rabbani, Mohammad; Mahzuni, Parvin

    2012-01-01

    Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the intestinal tract whose etiology has not yet been fully elucidated. Available medicines for treatment of IBD are not universally effective and result in marked deleterious effects. This challenge has thus heightened the need for research in order to adopt new therapeutic approaches for the treatment of IBD. 5-HT3 receptor antagonists have shown analgesic and anti-inflammatory properties in vitro and in vivo. Our aim was to investigate the effect of ondansetron, 5-HT3 receptor antagonist, in an immune-based animal model of IBD, trinitrobenzene sulfonic acid (TNBS)-induced rat colitis and probable involvement of 5-HT3 receptors. Two hours after induction of colitis (instillation of 50 mg/kg of TNBS dissolved in 0.25 ml of ethanol 50 % v/v) to male Wistar rats, ondansetron (2 mg/kg), dexamethasone (1 mg/kg), meta-chlorophenylbiguanide (mCPBG, 5 mg/kg), a 5-HT3 receptor agonist, or ondansetron + mCPBG were administrated intraperitoneally (ip) and continued daily for six days. The animals were sacrificed and distal colons were assessed macroscopically, histologically and biochemically [myeloperoxidase (MPO), tumor necrosis factor-alpha, interleukin-6 and interleukin-1 beta]. Ondansetron and dexamethasone resulted in a decrease in macroscopic and microscopic colonic damage significantly. In addition a dramatic reduction in MPO activity and colonic levels of inflammatory cytokines were seen. The protective effects of ondansetron were antagonized by concurrent administration of mCPBG. Our data suggests that the beneficial effects of ondansetron in TNBS-induced colitis could be mediated by 5-HT3 receptors. PMID:27350767

  2. Occupancy of α7 Nicotinic Acetylcholine Receptors in the Brain by Tropisetron: A Positron Emission Tomography Study Using [11C]CHIBA-1001 in Healthy Human Subjects

    PubMed Central

    Ishikawa, Masatomo; Sakata, Muneyuki; Toyohara, Jun; Oda, Keiichi; Ishii, Kenji; Wu, Jin; Yoshida, Taisuke; Iyo, Masaomi; Ishiwata, Kiichi

    2011-01-01

    Objective Agonists of α7-nicotinic acetylcholine receptors (nAChRs) have been developed as potential therapeutic drugs for neuropsychiatric diseases such as schizophrenia and Alzheimer's disease. Positron emission tomography (PET) is a noninvasive brain imaging technique to measure receptor occupancy in the living human brain. Although much effort has been expended to create specific PET radioligands for α7-nAChRs in the brain, only 4-[11C]methylphenyl-1,4-diazabicyclo[3.2.2.]nonane-4-carboxylate ([11C]CHIBA-1001) is currently available for clinical studies. In contrast, two 5-hydroxytryptamine-3 (5-HT3) receptor antagonists, tropisetron and ondansetron, have been used to treat patients with chemotherapy-induced or postoperative nausea and vomiting. Furthermore, tropisetron, but not ondansetron, possesses high affinity for α7-nAChRs. In the present study, we evaluated the receptor occupancy in the human brain after a single oral administration of tropisetron and ondansetron using [11C]CHIBA-1001 and PET. Methods Two serial dynamic PET scans using [11C]CHIBA-1001 in healthy non-smoking male subjects were performed before and after receiving an oral administration of these medications. Results A single oral administration of tropisetron, but not ondansetron, decreased the total distribution volume of [11C]CHIBA-1001 in the human brain. Conclusion This study shows that tropisetron, but not ondansetron, could bind to α7-nAChRs in the human brain after a single oral administration. Therefore, [11C]CHIBA-1001 may be a useful PET radioligand to measure the occupancy of α7-nAChRs in the human brain. PMID:23430308

  3. Contrasting effects of 5-HT3 receptor stimulation of the nucleus accumbens or ventral tegmentum on food intake in the rat.

    PubMed

    Pratt, Wayne E; Lin, Peagan; Pierce-Messick, Zachary; Ilesanmi, Adeolu O; Clissold, Kara A

    2017-04-14

    Although serotonin (5-HT) signaling is known to regulate food intake and energy homeostasis, the roles of the 5-HT3 receptor in feeding processes have been elusive. 5-HT3 receptors are found throughout mesolimbic circuitry that promote feeding not only in response to hunger, but also to the palatable and rewarding properties of food. These experiments examined if stimulation or blockade of the 5-HT3 receptor of the nucleus accumbens (NAcc) or ventral tegmentum affected food intake in the rat in response to hunger or the presence of a palatable diet. Rats (N=6-9/group) received bilateral injections of the 5-HT3 agonist m-chlorophenylbiguanide hydrochloride (mCPBG; at 0.0, 10.0, or 20.0μg/0.5μl/side) or the 5-HT3 antagonist ondansetron hydrochloride (at 0.0, 1.0, 2.0, or 5.0μg/0.5μl/side) into either the NAcc or the ventral tegmentum. NAcc 5-HT3 receptor stimulation significantly increased 2-h food intake in food-deprived animals offered rat chow and in a separate group of unrestricted rats offered a sweetened fat diet. In contrast to the feeding increase seen with NAcc treatments, stimulation of 5-HT3 receptors of the ventral tegmentum significantly reduced food and water intake in food-restricted animals; reductions of intake in non-restricted rats offered the palatable diet did not approach significance. Blockade of the 5-HT3 receptor had no effect on feeding in either brain region. These data support a functional role for serotonergic signaling in the mesolimbic pathway on motivated behavior, and demonstrate that 5-HT3 receptors differentially modulate food consumption in a region-dependent manner.

  4. 5-HT3 receptor blocking activity of arylalkanes isolated from the rhizome of Zingiber officinale.

    PubMed

    Abdel-Aziz, H; Nahrstedt, A; Petereit, F; Windeck, T; Ploch, M; Verspohl, E J

    2005-07-01

    Different extracts (ethanolic, hexane, aqueous) of ginger (rhizomes of Zingiber officinale) and the essential oil were tested using [14C]guanidinium influx into N1E-115 cells and the isolated rat ileum in order to identify their activity in inhibiting 5-HT3 receptor function. The hexane extract proved to be the most active and yielded upon bioassay-guided fractionation nine constituents: [6]-, [8]-, [10]-gingerols, [6]- and [8]-shogaols which were previously shown as active in vivo against cytotoxic drug-induced emesis; [4]-gingerol, [6]-gingerdiol, diacetyl-[6]-gingerdiol and [6]-dehydrogingerdione have not been previously tested for anti-emetic or 5-HT3 receptor antagonistic effects. Even though the latter four compounds are only minor constituents, their identification contributed towards the characterisation of a structure-activity relationship of this class of compounds. The order of potency for the nine constituents in the N1E-115 cell system was [6]-gingerdiol approximately diacetyl-[6]-gingerdiol approximately [6]-dehydrogingerdione approximately [6]-shogaol > or = [8]-shogaol approximately [8]-gingerol > [10]-gingerol > or = [6]-gingerol > [4]-gingerol.

  5. Building a 5-HT3A Receptor Expression Map in the Mouse Brain

    PubMed Central

    Koyama, Yoshihisa; Kondo, Makoto; Shimada, Shoichi

    2017-01-01

    Of the many serotonin receptors, the type 3 receptors (5-HT3R) are the only ionotropic ones, playing a key role in fast synaptic transmission and cognitive and emotional brain function through controlled neuronal excitation. To better understand the various functions of 5-HT3Rs, it is very important to know their expression pattern in the central nervous system (CNS). To date, many distributional studies have shown localized 5-HT3R expression in the brain and spinal cord. However, an accurate pattern of 5-HT3R expression in the CNS remains to be elucidated. To investigate the distribution of 5-HT3R in the mouse brain in detail, we performed immunofluorescent staining using 5-HT3AR-GFP transgenic mice. We found strong 5-HT3AR expression in the olfactory bulb, cerebral cortex, hippocampus, and amygdala; and partial expression in the pons, medulla, and spinal cord. Meanwhile, the thalamus, hypothalamus, and midbrain exhibited a few 5-HT3AR-expressing cells, and no expression was detected in the cerebellum. Further, double-immunostaining using neural markers confirmed that 5-HT3AR is expressed in GABAergic interneurons containing somatostatin or calretinin. In the present study, we built a 5-HT3AR expression map in the mouse brain. Our findings make significant contributions in elucidating the novel functions of 5-HT3R in the CNS. PMID:28276429

  6. Blockade of 5-Ht3 receptors in the septal area increases Fos expression in selected brain areas.

    PubMed

    Urzedo-Rodrigues, Lilia S; Ferreira, Hilda S; Santana, Rejane Conceição; Luz, Carla Patrícia; Perrone, Camila F; Fregoneze, Josmara B

    2014-04-01

    Serotonin is widely distributed throughout the brain and is involved in a multiplicity of visceral, cognitive and behavioral responses. It has been previously shown that injections of different doses of ondansetron, a 5-HT3 receptor antagonist, into the medial septum/vertical limb of the diagonal band complex (MS/vDB) induce a hypertensive response in rats. On the other hand, administration of m-CPBG, a 5-HT3 agonist, into the MS/vDB inhibits the increase of blood pressure during restraint stress. However, it is unclear which neuronal circuitry is involved in these responses. The present study investigated Fos immunoreactive nuclei (Fos-IR) in different brain areas following the blockade of 5-HT3 receptors located in the MS/vDB in sham and in sinoaortic denervated (SAD) rats. Ondansetron injection into the MS/vDB increases Fos-IR in different brain areas including the limbic system (central amygdala and ventral part of the bed nucleus of the stria terminalis), hypothalamus (medial parvocellular parts of the paraventricular nucleus, anterodorsal preoptic area, dorsomedial hypothalamic nucleus), mesencephalon (ventrolateral periaqueductal gray region) and rhombencephalon (lateral parabrachial nucleus) in sham rats. Barodenervation results in higher Fos expression at the parvocellular and magnocellular part of the paraventricular nucleus, the lateral parabrachial nucleus, the central nucleus of amygdala, the locus coeruleus, the medial part of the nucleus of the solitary tract, the rostral ventrolateral medulla and the caudal ventrolateral medulla following 5-HT3receptor blockade in the MS/vDB. Based on the present results and previous data showing a hypertensive response to ondansetron injected into the MS/vDB, it is reasonable to suggest that 5-HT3receptors in the MS/vDB exert an inhibitory drive that may oscillate as a functional regulatory part of the complex central neuronal network participating in the control of blood pressure.

  7. Kampo Medicine: Evaluation of the Pharmacological Activity of 121 Herbal Drugs on GABAA and 5-HT3A Receptors

    PubMed Central

    Hoffmann, Katrin M.; Herbrechter, Robin; Ziemba, Paul M.; Lepke, Peter; Beltrán, Leopoldo; Hatt, Hanns; Werner, Markus; Gisselmann, Günter

    2016-01-01

    Kampo medicine is a form of Japanese phytotherapy originating from traditional Chinese medicine (TCM). During the last several decades, much attention has been paid to the pharmacological effects of these medical plants and their constituents. However, in many cases, a systematic screening of Kampo remedies to determine pharmacologically relevant targets is still lacking. In this study, a broad screening of Kampo remedies was performed to look for pharmacologically relevant 5-HT3A and GABAA receptor ligands. Several of the Kampo remedies are currently used for symptoms such as nausea, emesis, gastrointestinal motility disorders, anxiety, restlessness, or insomnia. Therefore, the pharmacological effects of 121 herbal drugs from Kampo medicine were analyzed as ethanol tinctures on heterologously expressed 5-HT3A and GABAA receptors, due to the involvement of these receptors in such pathophysiological processes. The tinctures of Lindera aggregata (radix) and Leonurus japonicus (herba) were the most effective inhibitory compounds on the 5-HT3A receptor. Further investigation of known ingredients in these compounds led to the identification of leonurine from Leonurus as a new natural 5-HT3A receptor antagonist. Several potentiating herbs (e.g., Magnolia officinalis (cortex), Syzygium aromaticum (flos), and Panax ginseng (radix)) were also identified for the GABAA receptor, which are all traditionally used for their sedative or anxiolytic effects. A variety of tinctures with antagonistic effects Salvia miltiorrhiza (radix) were also detected. Therefore, this study reveals new insights into the pharmacological action of a broad spectrum of herbal drugs from Kampo, allowing for a better understanding of their physiological effects and clinical applications. PMID:27524967

  8. [Pharmacoeconomical model for cost calculation using a study on prophylaxis of nausea and vomiting in the postoperative phase as an example. Cost effectiveness analysis of a tropisetron supplemented desflurane anaesthesia in comparison to a propofol total intravenous anaesthesia (TIVA)].

    PubMed

    Eberhart, L H J; Bernert, S; Wulf, H; Geldner, G

    2002-06-01

    Postoperative nausea and vomiting (PONV) are among the most frequent complications after general anaesthesia. Avoiding these symptoms is of utmost importance for most patients; PONV is not only a major source of discomfort for patients but also a cause of additional costs for the patients and the health care provider. The economical impact of PONV will become even more important in the near future because the number of surgical procedures performed on an ambulatory basis is increasing. The following article gives a short overview of the terminology and measures used in pharmacoeconomical studies concerning PONV. Furthermore the economical aspects of a low-flow anaesthesia supplemented with the 5-HT(3)-antagonist tropisetron compared with a total intravenous anaesthesia (TIVA) using propofol are described. For this comparison a decision analysis was performed using data of a randomised control trial on 150 female patients undergoing major gynaecological surgery. The patients were randomised to receive a total intravenous anaesthesia with propofol-alfentanil or a balanced anaesthesia with desfluran (fresh gas flow 1 l.min(-1)) supplemented by 2 mg tropisetron at the end of surgery. Indirect costs associated with anaesthesia using desflurane-tropisetron (4.94 Euro) are not different from that of propofol-TIVA (4.81 Euro) because of a similar incidence of PONV in the PACU. Furthermore, the total cost for 100 min general anaesthesia is higher in the desflurane-tropisetron group (30.94 Euro) compared with the TIVA group (24.55 Euro) due to the decreasing acquisition costs of propofol in the last 2 years. Total intravenous anaesthesia with propofol is more cost-efficient than balanced anaesthesia with desflurane and additional tropisetron as a prophylactic antiemetic.

  9. Design, Synthesis, and Structure–Activity Relationships of Highly Potent 5-HT3 Receptor Ligands

    PubMed Central

    2012-01-01

    The 5-HT3 receptor, a pentameric ligand-gated ion channel (pLGIC), is an important therapeutic target. During a recent fragment screen, 6-chloro-N-methyl-2-(4-methyl-1,4-diazepan-1-yl)quinazolin-4-amine (1) was identified as a 5-HT3R hit fragment. Here we describe the synthesis and structure–activity relationships (SAR) of a series of (iso)quinoline and quinazoline compounds that were synthesized and screened for 5-HT3R affinity using a [3H]granisetron displacement assay. These studies resulted in the discovery of several high affinity ligands of which compound 22 showed the highest affinity (pKi > 10) for the 5-HT3 receptor. The observed SAR is in agreement with established pharmacophore models for 5-HT3 ligands and is used for ligand–receptor binding mode prediction using homology modeling and in silico docking approaches. PMID:23006041

  10. Lamotrigine, an antiepileptic drug, inhibits 5-HT3 receptor currents in NCB-20 neuroblastoma cells

    PubMed Central

    Kim, Ki Jung; Jeun, Seung Hyun

    2017-01-01

    Lamotrigine is an antiepileptic drug widely used to treat epileptic seizures. Using whole-cell voltage clamp recordings in combination with a fast drug application approach, we investigated the effects of lamotrigine on 5-hydroxytryptamine (5-HT)3 receptors in NCB-20 neuroblastoma cells. Co-application of lamotrigine (1~300 µM) resulted in a concentration-dependent reduction in peak amplitude of currents induced by 3 µM of 5-HT for an IC50 value of 28.2±3.6 µM with a Hill coefficient of 1.2±0.1. These peak amplitude decreases were accompanied by the rise slope reduction. In addition, 5-HT3-mediated currents evoked by 1 mM dopamine, a partial 5-HT3 receptor agonist, were inhibited by lamotrigine co-application. The EC50 of 5-HT for 5-HT3 receptor currents were shifted to the right by co-application of lamotrigine without a significant change of maximal effect. Currents activated by 5-HT and lamotrigine co-application in the presence of 1 min pretreatment of lamotrigine were similar to those activated by 5-HT and lamotrigine co-application alone. Moreover, subsequent application of lamotrigine in the presence of 5-HT and 5-hydroxyindole, known to attenuate 5-HT3 receptor desensitization, inhibited 5-HT3 receptor currents in a concentration-dependent manner. The deactivation of 5-HT3 receptor was delayed by washing with an external solution containing lamotrigine. Lamotrigine accelerated the desensitization process of 5-HT3 receptors. There was no voltage-dependency in the inhibitory effects of lamotrigine on the 5-HT3 receptor currents. These results indicate that lamotrigine inhibits 5-HT3-activated currents in a competitive manner by binding to the open state of the channels and blocking channel activation or accelerating receptor desensitization. PMID:28280410

  11. Lamotrigine, an antiepileptic drug, inhibits 5-HT3 receptor currents in NCB-20 neuroblastoma cells.

    PubMed

    Kim, Ki Jung; Jeun, Seung Hyun; Sung, Ki-Wug

    2017-03-01

    Lamotrigine is an antiepileptic drug widely used to treat epileptic seizures. Using whole-cell voltage clamp recordings in combination with a fast drug application approach, we investigated the effects of lamotrigine on 5-hydroxytryptamine (5-HT)3 receptors in NCB-20 neuroblastoma cells. Co-application of lamotrigine (1~300 µM) resulted in a concentration-dependent reduction in peak amplitude of currents induced by 3 µM of 5-HT for an IC50 value of 28.2±3.6 µM with a Hill coefficient of 1.2±0.1. These peak amplitude decreases were accompanied by the rise slope reduction. In addition, 5-HT3-mediated currents evoked by 1 mM dopamine, a partial 5-HT3 receptor agonist, were inhibited by lamotrigine co-application. The EC50 of 5-HT for 5-HT3 receptor currents were shifted to the right by co-application of lamotrigine without a significant change of maximal effect. Currents activated by 5-HT and lamotrigine co-application in the presence of 1 min pretreatment of lamotrigine were similar to those activated by 5-HT and lamotrigine co-application alone. Moreover, subsequent application of lamotrigine in the presence of 5-HT and 5-hydroxyindole, known to attenuate 5-HT3 receptor desensitization, inhibited 5-HT3 receptor currents in a concentration-dependent manner. The deactivation of 5-HT3 receptor was delayed by washing with an external solution containing lamotrigine. Lamotrigine accelerated the desensitization process of 5-HT3 receptors. There was no voltage-dependency in the inhibitory effects of lamotrigine on the 5-HT3 receptor currents. These results indicate that lamotrigine inhibits 5-HT3-activated currents in a competitive manner by binding to the open state of the channels and blocking channel activation or accelerating receptor desensitization.

  12. Design and validation of a homogeneous time-resolved fluorescence cell-based assay targeting the ligand-gated ion channel 5-HT3A.

    PubMed

    Blanc, Emilie; Wagner, Patrick; Plaisier, Fabrice; Schmitt, Martine; Durroux, Thierry; Bourguignon, Jean-Jacques; Partiseti, Michel; Dupuis, Elodie; Bihel, Frederic

    2015-09-01

    Ligand-gated ion channels (LGICs) are considered as attractive protein targets in the search for new therapeutic agents. Nowadays, this strategy involves the capability to screen large chemical libraries. We present a new Tag-lite ligand binding assay targeting LGICs on living cells. This technology combines the use of suicide enzyme tags fused to channels of interest with homogeneous time-resolved fluorescence (HTRF) as the detection readout. Using the 5-HT3 receptor as system model, we showed that the pharmacology of the HALO-5HT3 receptor was identical to that of the native receptor. After validation of the assay by using 5-HT3 agonists and antagonists of reference, a pilot screen enabled us to identify azelastine, a well-known histamine H1 antagonist, as a potent 5-HT3 antagonist. This interesting result was confirmed with electrophysiological experiments. The method described here is easy to implement and could be applicable for other LGICs, opening new ways for the screening of chemical libraries.

  13. Functional expression and properties of a nicotinic alpha9/5-HT3A chimeric receptor.

    PubMed

    Verbitsky, Miguel; Plazas, Paola V; Elgoyhen, A Belén

    2003-10-27

    We describe the functional properties of a nicotinic alpha9/serotonin subtype 3A (5HT3A) chimeric receptor expressed in Xenopus laevis oocytes. The chimera preserved ligand-binding properties of alpha9 and channel properties of 5HT3A. Thus, it responded to acetylcholine in a concentration-dependent manner with an EC50 of 70 microM but not to serotonin. It was blocked by methyllycaconitine, strychnine, atropine and nicotine, with the same rank order of potency as alpha9 receptors. The current-voltage relationship of currents through the alpha9/5HT3A chimera was similar to that of the 5HT3A receptors. These results are an evidence of functional coupling between the ligand-binding and the channel domains of the chimeric receptor.

  14. Anxiolytic-like effect of a serotonergic ligand with high affinity for 5-HT1A, 5-HT2A and 5-HT3 receptors.

    PubMed

    Delgado, Mercedes; Caicoya, Anne G; Greciano, Virginia; Benhamú, Bellinda; López-Rodríguez, María Luz; Fernández-Alfonso, María Soledad; Pozo, Miguel A; Manzanares, Jorge; Fuentes, José A

    2005-03-21

    S-(-)-2-[[4-(napht-1-yl)piperazin-1-yl]methyl]-1,4-dioxoperhydropyrrolo[1,2-alpha]-pyrazine (CSP-2503) is a serotonin (5-HT) receptor ligand with selectivity and high affinity for 5-HT1A, 5-HT2A and 5-HT3 receptors. CSP-2503 reduced rectal temperature and 5-HT neuronal hypothalamic activity in mice, decreased electrical activity of raphe nuclei cells in rats and blocked the enhancement of adenylate cyclase activity induced by forskolin in HeLa cells transfected with the human 5-HT1A receptor. This compound also blocked head-twitches induced by the 5-HT(2A/2C) receptor agonist 2,5-dimethoxy-4-iodoamphetamine (DOI). Contractions of guinea pig ileum induced by the 5-HT3 receptor agonist 2-methyl-5-HT were prevented by CSP-2503. Moreover, it reduced the bradycardia reflex induced by 2-methyl-5-HT in anaesthetized rats. In the light/dark box and social interaction tests, CSP-2503 presented anxiolytic activity, an action shared by 5-HT1 agonists and 5-HT3 antagonists. Taken together, these results suggest that CSP-2503 is a new 5-HT1 receptor agonist with 5-HT2A and 5-HT3)receptor antagonist activities that might be useful in a number of conditions associated with anxiety.

  15. Roles of serotonin 5-HT3 receptor in the formation of dendrites and axons in the rat cerebral cortex: an in vitro study.

    PubMed

    Hayashi, Takahiro; Ohtani, Akiko; Onuki, Fumiaki; Natsume, Masaki; Li, Fei; Satou, Tomomi; Yoshikawa, Masaaki; Senzaki, Kouji; Shiga, Takashi

    2010-01-01

    The serotonin type 3 (5-HT(3)) receptor is an only ligand-gated ion channel among 14 serotonin receptors. Here, we examined the roles of the 5-HT(3) receptor in the formation of dendrites and axons, using a dissociation culture of embryonic rat cerebral cortex. Cortical neurons at embryonic day 16 were cultured for 4 days in the presence of a selective 5-HT(3) receptor agonist with or without an antagonist. Neurons were then immunostained by antibodies against microtubule-associated protein 2 (MAP2) and glutamic acid decarboxylase (GAD) 65. All cells expressed MAP2, whereas only limited number of cells expressed GAD65. From the immunoreactivity and the cell shape, we tentatively divided neurons into 3 types; GAD-positive multipolar, GAD-positive bipolar/tripolar and GAD-negative neurons. The total length of axons and dendrites, the number of primary dendrites and the dendritic branching of GAD-negative neurons were decreased by the agonist (10 or 100nM), most of which were reversed by the concomitant treatment of the antagonist. In contrast, no or little effect was observed on the formation of dendrites and axons of GAD-positive multipolar neurons, and the neurite formation of GAD-positive bipolar/tripolar neurons. The present study revealed differential roles of the 5-HT(3) receptor in the formation of dendrites and axons of subtypes of cortical neurons.

  16. The rapid recovery of 5-HT cell firing induced by the antidepressant vortioxetine involves 5-HT(3) receptor antagonism.

    PubMed

    Bétry, Cécile; Pehrson, Alan L; Etiévant, Adeline; Ebert, Bjarke; Sánchez, Connie; Haddjeri, Nasser

    2013-06-01

    The therapeutic effect of current antidepressant drugs appears after several weeks of treatment and a significant number of patients do not respond to treatment. Here, we report the effects of the multi-modal antidepressant vortioxetine (Lu AA21004), a 5-HT(3) and 5-HT(7) receptor antagonist, 5-HT(1B) receptor partial agonist, 5-HT(1A) receptor agonist and 5-HT transporter (SERT) inhibitor, on rat 5-HT neurotransmission. Using in vivo electrophysiological recordings in the dorsal raphe nucleus of anaesthetized rats, we assessed the acute and subchronic effects of vortioxetine and/or the selective 5-HT(3) receptor agonist, SR57227 or the selective 5-HT(1A) receptor agonist flesinoxan, on 5-HT neuronal firing activity. Using ex-vivo autoradiography, we correlated SERT occupancy and presumed 5-HT firing activity. The selective serotonin reuptake inhibitor, fluoxetine, was used as comparator. Importantly, the recovery of 5-HT neuronal firing was achieved after 1 d with vortioxetine and 14 d with fluoxetine. SR57227 delayed this recovery. In contrast, vortioxetine failed to alter the reducing action of 3 d treatment of flesinoxan. Acute dosing of vortioxetine inhibited neuronal firing activity more potently than fluoxetine. SR57227 prevented the suppressant effect of vortioxetine, but not of fluoxetine. In contrast, flesinoxan failed to modify the suppressant effect of vortioxetine acutely administered. Differently to fluoxetine, vortioxetine suppressed neuronal firing without saturating occupancy at the SERT. Vortioxetine produced a markedly faster recovery of 5-HT neuronal firing than fluoxetine. This is at least partly due to 5-HT(3) receptor antagonism of vortioxetine in association with its reduced SERT occupancy.

  17. The Impact of 5-HT3RA Use on Cost and Utilization in Patients with Chemotherapy-Induced Nausea and Vomiting: Systematic Review of the Literature

    PubMed Central

    Broder, Michael S.; Faria, Claudio; Powers, Annette; Sunderji, Jehangeer; Cherepanov, Dasha

    2014-01-01

    Background Individual studies have assessed the impact of standard prophylactic therapy with 5-hydroxytryptamine receptor antagonists (5-HT3RAs) for chemotherapy-induced nausea and vomiting (CINV) on cost and utilization, but no synthesis of the findings exists. Objective To systematically review published literature on costs and utilization associated with CINV prophylaxis with palonosetron and other 5-HT3RAs. Methods PubMed and the National Institute for Health Research Centre for Reviews and Dissemination databases, conferences of 4 organizations (ie, Academy of Managed Care Pharmacy, American Society of Clinical Oncology, International Society for Pharmacoeconomics and Outcomes Research, and Multinational Association of Supportive Care in Cancer), and the bibliographies of relevant articles were queried for the medical subject headings and key terms of “ondansetron,” “granisetron,” “palonosetron,” “dolasetron mesylate,” “costs,” “cost analysis,” and “economics.” We included records published (full-length articles after 1997 and conference presentations after 2010) in English and with human patients, reporting data on cost and utilization (rescue medication, outpatient and inpatient services) associated with the use of 5-HT3RAs for the treatment or prevention of CINV. Results Of the 434 identified studies, 32 are included in the current analysis: 7 studies report costs, 18 report utilization, and 7 studies report both. The costs are reported in US dollars (7 studies), in Euros (5 studies), and in Canadian dollars (2 studies). The studies vary in designs, patients, 5-HT3RA regimens, and the definition of outcomes. The US studies report higher drug costs for CINV prophylaxis with palonosetron compared with ondansetron, lower medical outpatient and inpatient costs for palonosetron versus other 5-HT3RAs, and higher acquisition costs for palonosetron versus ondansetron or other 5-HT3RAs. Fewer patients receiving palonosetron versus with

  18. Role of central vagal 5-HT3 receptors in gastrointestinal physiology and pathophysiology

    PubMed Central

    Browning, Kirsteen N.

    2015-01-01

    Vagal neurocircuits are vitally important in the co-ordination and modulation of GI reflexes and homeostatic functions. 5-hydroxytryptamine (5-HT; serotonin) is critically important in the regulation of several of these autonomic gastrointestinal (GI) functions including motility, secretion and visceral sensitivity. While several 5-HT receptors are involved in these physiological responses, the ligand-gated 5-HT3 receptor appears intimately involved in gut-brain signaling, particularly via the afferent (sensory) vagus nerve. 5-HT is released from enterochromaffin cells in response to mechanical or chemical stimulation of the GI tract which leads to activation of 5-HT3 receptors on the terminals of vagal afferents. 5-HT3 receptors are also present on the soma of vagal afferent neurons, including GI vagal afferent neurons, where they can be activated by circulating 5-HT. The central terminals of vagal afferents also exhibit 5-HT3 receptors that function to increase glutamatergic synaptic transmission to second order neurons of the nucleus tractus solitarius within the brainstem. While activation of central brainstem 5-HT3 receptors modulates visceral functions, it is still unclear whether central vagal neurons, i.e., nucleus of the tractus solitarius (NTS) and dorsal motor nucleus of the vagus (DMV) neurons themselves also display functional 5-HT3 receptors. Thus, activation of 5-HT3 receptors may modulate the excitability and activity of gastrointestinal vagal afferents at multiple sites and may be involved in several physiological and pathophysiological conditions, including distention- and chemical-evoked vagal reflexes, nausea, and vomiting, as well as visceral hypersensitivity. PMID:26578870

  19. Immunohistochemical characterization of 5-HT(3A) receptors in the Syrian hamster forebrain.

    PubMed

    Carrillo, Maria; Ricci, Lesley A; Schwartzer, Jared J; Melloni, Richard H

    2010-05-06

    The Syrian hamster (Mesocricetus auratus) has been extensively used as an animal model to investigate neuronal networks underlying various behaviors where 5-HT(3A) receptors have been found to play a critical role. To date, however, there is no comprehensive description of the distribution of 5-HT(3A) receptors in the Syrian hamster brain. The current study examined the localization of 5-HT(3A) receptors across the neuraxis of the Syrian hamster forebrain using immunohistochemistry. Overall, 5-HT(3A) receptors were widely and heterogeneously distributed across the neuraxis of the Syrian hamster brain. Notably, the most intense 5-HT(3A) immunolabeling patterns were observed in the cerebral cortex and amygdala. In addition, high variability in receptor density and expression patterns (i.e., perikarya, fibers and/or neuropilar puncta) was observed within the majority of brain areas examined, indicating that the role this receptor has in the modulation of a particular neural function differs depending on brain region. In some regions (i.e., nucleus accumbens) differences in the immunolabeling pattern between rostral, medial and caudal portions were also observed, suggesting functional heterogeneity of this receptor within a single brain region. Together, these results and the localization of this receptor to brain areas involved in the regulation of sexual behavior, aggression, circadian rhythm, drug abuse and anxiety implicate 5-HT(3A) receptors in the modulation of various behaviors and neural functions in the Syrian hamster. Further, these results underscore the importance of evaluating 5-HT(3A) receptors as a pharmacological target for the treatment of various psychopathological disorders.

  20. The role of 5-HT3 receptors in drug abuse and as a target for pharmacotherapy.

    PubMed

    Engleman, E A; Rodd, Z A; Bell, R L; Murphy, J M

    2008-11-01

    Alcohol and drug abuse continue to be a major public health problem in the United States and other industrialized nations. Extensive preclinical research indicates the mesolimbic dopamine (DA) pathway and associated regions mediate the rewarding and reinforcing effects of drugs of abuse and natural rewards, such as food and sex. The serotonergic (5-HT) system, in concert with others neurotransmitter systems, plays a key role in modulating neuronal systems within the mesolimbic pathway. A substantial portion of this modulation is mediated by activity at the 5-HT3 receptor. The 5-HT3 receptor is unique among the 5-HT receptors in that it directly gates an ion channel inducing rapid depolarization that, in turn, causes the release of neurotransmitters and/or peptides. Preclinical findings indicate that antagonism of the 5-HT3 receptor in the ventral tegmental area, nucleus accumbens or amygdala reduces alcohol self-administration and/or alcohol-associated effects. Less is known about the effects of 5-HT3 receptor activity on the self-administration of other drugs of abuse or their associated effects. Clinical findings parallel the preclinical findings such that antagonism of the 5-HT3 receptor reduces alcohol consumption and some of its subjective effects. This review provides an overview of the structure, function, and pharmacology of 5-HT3 receptors, the role of these receptors in regulating DA neurotransmission in mesolimbic brain areas, and discusses data from animal and human studies implicating 5-HT3 receptors as targets for the development of new pharmacological agents to treat addictions.

  1. The Role of 5-HT3 Receptors in Drug Abuse and as a Target for Pharmacotherapy

    PubMed Central

    Engleman, E.A.; Rodd, Z.A.; Bell, R.L.; Murphy, J.M.

    2010-01-01

    Alcohol and drug abuse continue to be a major public health problem in the United States and other industrialized nations. Extensive preclinical research indicates the mesolimbic dopamine (DA) pathway and associated regions mediate the rewarding and reinforcing effects of drugs of abuse and natural rewards, such as food and sex. The serotonergic (5-HT) system, in concert with others neurotransmitter systems, plays a key role in modulating neuronal systems within the mesolimbic pathway. A substantial portion of this modulation is mediated by activity at the 5-HT3 receptor. The 5-HT3 receptor is unique among the 5-HT receptors in that it directly gates an ion channel inducing rapid depolarization that, in turn, causes the release of neurotransmitters and/or peptides. Preclinical findings indicate that antagonism of the 5-HT3 receptor in the ventral tegmental area, nucleus accumbens or amygdala reduces alcohol self-administration and/or alcohol-associated effects. Less is known about the effects of 5-HT3 receptor activity on the self-administration of other drugs of abuse or their associated effects. Clinical findings parallel the preclinical findings such that antagonism of the 5-HT3 receptor reduces alcohol consumption and some of its subjective effects. This review provides an overview of the structure, function, and pharmacology of 5-HT3 receptors, the role of these receptors in regulating DA neurotransmission in mesolimbic brain areas, and discusses data from animal and human studies implicating 5-HT3 receptors as targets for the development of new pharmacological agents to treat addictions. PMID:19128203

  2. Pathways and Barriers for Ion Translocation through the 5-HT3A Receptor Channel

    PubMed Central

    Di Maio, Danilo; Chandramouli, Balasubramanian; Brancato, Giuseppe

    2015-01-01

    Pentameric ligand gated ion channels (pLGICs) are ionotropic receptors that mediate fast intercellular communications at synaptic level and include either cation selective (e.g., nAChR and 5-HT3) or anion selective (e.g., GlyR, GABAA and GluCl) membrane channels. Among others, 5-HT3 is one of the most studied members, since its first cloning back in 1991, and a large number of studies have successfully pinpointed protein residues critical for its activation and channel gating. In addition, 5-HT3 is also the target of a few pharmacological treatments due to the demonstrated benefits of its modulation in clinical trials. Nonetheless, a detailed molecular analysis of important protein features, such as the origin of its ion selectivity and the rather low conductance as compared to other channel homologues, has been unfeasible until the recent crystallization of the mouse 5-HT3A receptor. Here, we present extended molecular dynamics simulations and free energy calculations of the whole 5-HT3A protein with the aim of better understanding its ion transport properties, such as the pathways for ion permeation into the receptor body and the complex nature of the selectivity filter. Our investigation unravels previously unpredicted structural features of the 5-HT3A receptor, such as the existence of alternative intersubunit pathways for ion translocation at the interface between the extracellular and the transmembrane domains, in addition to the one along the channel main axis. Moreover, our study offers a molecular interpretation of the role played by an arginine triplet located in the intracellular domain on determining the characteristic low conductance of the 5-HT3A receptor, as evidenced in previous experiments. In view of these results, possible implications on other members of the superfamily are suggested. PMID:26465896

  3. Hypoxia switches episodic breathing to singlet breathing in red-eared slider turtles (Trachemys scripta) via a tropisetron-sensitive mechanism.

    PubMed

    Johnson, Stephen M; Krisp, Ashley R; Bartman, Michelle E

    2015-02-01

    Hypoxia-induced changes in the chelonian breathing pattern are poorly understood. Thus, breathing was measured in freely swimming adult red-eared slider turtles breathing air prior to breathing nitrogen for 4h. Ventilation increased 10-fold within 10min due to increased breath frequency and tidal volume. Breaths/episode decreased by ∼50% within after 1h of hypoxia while the number of singlet breaths increased from 3.1±1.6singlets/h to a maximum of 66.1±23.5singlets/h. Expiratory and inspiratory duration increased during hypoxia. For doublet and triplet breaths, expiratory duration increased during the first breath only, while inspiratory duration increased for all breaths. Tropisetron (5-HT3 receptor antagonist, 5mg/kg) administration prior to hypoxia attenuated the hypoxia-induced increase in singlet breath frequency. Along with results from previous in vitro studies, this study suggests that 5-HT3 receptor activation may be required for the hypoxia-induced increase in singlet breathing pattern in red-eared slider turtles.

  4. Quantitation of 5HT3 receptors in forebrain of serotonin transporter deficient mice.

    PubMed

    Mössner, R; Schmitt, A; Hennig, T; Benninghoff, J; Gerlach, M; Riederer, P; Deckert, J; Lesch, K P

    2004-01-01

    Mice deficient in the serotonin transporter (5HTT) display highly elevated extracellular 5HT levels. 5HT exerts ist effects via at least fourteen different cloned 5HT receptors located pre- and postsynaptically. In contrast to the other 5HT receptors, the 5HT3 receptor is a ionotropic receptor with ligand-gated cation channel function. Since G-protein-coupled 5HT receptors show extensive adaptive changes in 5HTT-deficient mice, we investigated whether 5HT3 receptors are also altered in these mice. Using quantitative autoradiography, we found that 5HT3 receptors are upregulated in frontal cortex (+46%), parietal cortex (+42%), and in stratum oriens of the CA3 region of the hippocampus (+18%) of 5HTT knockout mice. Changes in 5HT3 receptor mRNA expression, as determined by quantitative in situ hybridisation, were less pronounced. The adaptive changes of 5HT3 receptor expression constitute a part of the complex regulatory pattern of 5HT receptors in 5HTT knockout mice.

  5. The Structure of the Mouse Serotonin 5-HT3 Receptor in Lipid Vesicles.

    PubMed

    Kudryashev, Mikhail; Castaño-Díez, Daniel; Deluz, Cédric; Hassaine, Gherici; Grasso, Luigino; Graf-Meyer, Alexandra; Vogel, Horst; Stahlberg, Henning

    2016-01-05

    The function of membrane proteins is best understood if their structure in the lipid membrane is known. Here, we determined the structure of the mouse serotonin 5-HT3 receptor inserted in lipid bilayers to a resolution of 12 Å without stabilizing antibodies by cryo electron tomography and subtomogram averaging. The reconstruction reveals protein secondary structure elements in the transmembrane region, the extracellular pore, and the transmembrane channel pathway, showing an overall similarity to the available X-ray model of the truncated 5-HT3 receptor determined in the presence of a stabilizing nanobody. Structural analysis of the 5-HT3 receptor embedded in a lipid bilayer allowed the position of the membrane to be determined. Interactions between the densely packed receptors in lipids were visualized, revealing that the interactions were maintained by the short horizontal helices. In combination with methodological improvements, our approach enables the structural analysis of membrane proteins in response to voltage and ligand gating.

  6. Molecular dynamics simulation of the structure and dynamics of 5-HT3 serotonin receptor

    NASA Astrophysics Data System (ADS)

    Antonov, M. Yu.; Popinako, A. V.; Prokopiev, G. A.

    2016-10-01

    In this work, we investigated structure, dynamics and ion transportation in transmembrane domain of the 5-HT3 serotonin receptor. High-resolution (0.35 nm) structure of the 5-HT3 receptor in complex with stabilizing nanobodies was determined by protein crystallography in 2014 (Protein data bank (PDB) code 4PIR). Transmembrane domain of the structure was prepared in complex with explicit membrane environment (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC)) and solvent (TIP3P water model). Molecular dynamics protocols for simulation and stabilization of the transmembrane domain of the 5-HT3 receptor model were developed and 60 ns simulation of the structure was conducted in order to explore structural parameters of the system. We estimated the mean force profile for Na+ ions using umbrella sampling method.

  7. Key role of 5-HT3 receptors in the nucleus tractus solitarii in cardiovagal stress reactivity.

    PubMed

    Sévoz-Couche, Caroline; Brouillard, Charly

    2017-03-01

    Serotonin plays a modulatory role in central control of the autonomic nervous system (ANS). The nucleus tractus solitarii (NTS) in the medulla is an area of viscerosomatic integration innervated by both central and peripheral serotonergic fibers. Influences from different origins therefore trigger the release of serotonin into the NTS and exert multiple influences on the ANS. This major influence on the ANS is also mediated by activation of several receptors in the NTS. In particular, the NTS is the central zone with the highest density of serotonin3 (5-HT3) receptors. In this review, we present evidence that 5-HT3 receptors in the NTS play a key role in one of the crucial homeostatic responses to acute and chronic stress: inhibitory modulation of the parasympathetic component of the ANS. The possible functional interactions of 5-HT3 receptors with GABAA and NK1 receptors in the NTS are also discussed.

  8. Investigation of 5-HT3 receptor-triggered serotonin release from guinea-pig isolated colonic mucosa: a role of PYY-containing endocrine cell.

    PubMed

    Kojima, Shu-Ichi; Kojima, Ken; Fujita, Tomoe

    2017-03-15

    The effect of a 5-HT3 receptor-selective agonist SR57227A was investigated on the outflow of 5-hydroxytryptamine (5-HT) from isolated muscle layer-free mucosal preparations of guinea-pig colon. The mucosal preparations were incubated in vitro and the outflow of 5-HT from these preparations was determined by high-performance liquid chromatography with electrochemical detection. SR57227A (100μM) produced a tetrodotoxin-resistant and sustained increase in the outflow of 5-HT from the mucosal preparations. The SR57227A-evoked sustained 5-HT outflow was completely inhibited by the 5-HT3 receptor antagonist ramosetron (1μM). The neuropeptide Y1 receptor antagonist BIBO3304 (100nM) partially inhibited the SR57227A-evoked sustained 5-HT outflow, but the Y2 receptor antagonist BIIE0246 (1μM) or the glucagon-like peptide-1 (GLP-1) receptor antagonist exendin-(9-39) (1μM), showed a minimal effect on the SR57227A-evoked sustained 5-HT outflow. In the presence of BIBO3304 (100nM) and exendin-(9-39) (1μM), SR57227A (100μM) failed to produce a sustained increase in the outflow of 5-HT. The Y1 receptor agonist [Leu(31), Pro(34)]-neuropeptide Y (10nM), but not GLP-1-(7-36) amide (100nM), produced a sustained increase in the outflow of 5-HT. We found that 5-HT3 receptor-triggered 5-HT release from guinea-pig colonic mucosa is mediated by the activation of 5-HT3 receptors located at endocrine cells (enterochromaffin cells and peptide YY (PYY)-containing endocrine cells). The activation of both Y1 and GLP-1 receptors appears to be required for the maintenance of 5-HT3 receptor-triggered 5-HT release. It is therefore considered that 5-HT3 receptors located at colonic mucosa play a crucial role in paracrine signaling between enterochromaffin cells and PYY-containing endocrine cells.

  9. Regulation of central noradrenergic activity by 5-HT(3) receptors located in the locus coeruleus of the rat.

    PubMed

    Ortega, Jorge E; Mendiguren, Aitziber; Pineda, Joseba; Meana, J Javier

    2012-06-01

    A functional interaction between serotonergic and noradrenergic systems has been shown in the locus coeruleus (LC). Noradrenaline (NA) levels in the prefrontal cortex (PFC) are dependent on the firing rate of LC neurons, which is controlled by α(2) adrenoceptors (α2ADR). The aim of the present study was to investigate the role of 5-HT(3) receptors (5HT3R) in the modulation of central noradrenergic activity. We measured extracellular NA concentrations in the LC and PFC by dual-probe microdialysis in awake rats and the firing rate of LC neurons by electrophysiological techniques in vitro. Administration of the 5HT3R agonists SR57227 (1-100 μM) and m-chlorophenylbiguanide (mCPBG, 1-100 μM) into the LC increased NA in this nucleus (E(max) = 675 ± 121% and E(max) = 5575 ± 1371%, respectively) and decreased NA in the PFC (E(max) = -49 ± 6% and E(max) = -25 ± 11%, respectively). Administration of the 5HT3R antagonist Y25130 (50 μM) into LC attenuated SR57227 effect in the LC (E(max) = 323 ± 28%) and PFC (E(max) = -37 ± 7%). The α2ADR antagonist RS79948 (1 μM) blocked the SR57227 effect in the PFC but it did not change the effect in the LC (E(max) = 677 ± 202%). In electrophysiological assays, both mCPBG (1-10 μM) and SR57227 (1-10 μM) reduced the firing rate of about 50% of tested LC neurons (maximal effect = -37 ± 2% and -31 ± 4%, respectively); this effect was partially blocked by Y25130 (50 μM). Administration of RS79948 (1 μM) reversed the inhibition induced by mCPBG. Competition radioligand assays against [(3)H]UK14304 and [(3)H]RX821002 (α2ADR selective drugs) in the rat brain cortex showed a very weak affinity of SR57227 for α2ADR, whereas the affinity of mCPBG for α2ADR was 17-fold higher than that of SR57227 for α2ADR. The present results suggest that 5HT3R stimulate NA release in the LC, which promotes simultaneously a decrease in the firing rate of LC neurons through α2ADR and then a decrease

  10. Discovery of a novel allosteric modulator of 5-HT3 receptors: inhibition and potentiation of Cys-loop receptor signaling through a conserved transmembrane intersubunit site.

    PubMed

    Trattnig, Sarah M; Harpsøe, Kasper; Thygesen, Sarah B; Rahr, Louise M; Ahring, Philip K; Balle, Thomas; Jensen, Anders A

    2012-07-20

    The ligand-gated ion channels in the Cys-loop receptor superfamily mediate the effects of neurotransmitters acetylcholine, serotonin, GABA, and glycine. Cys-loop receptor signaling is susceptible to modulation by ligands acting through numerous allosteric sites. Here we report the discovery of a novel class of negative allosteric modulators of the 5-HT(3) receptors (5-HT(3)Rs). PU02 (6-[(1-naphthylmethyl)thio]-9H-purine) is a potent and selective antagonist displaying IC(50) values of ~1 μM at 5-HT(3)Rs and substantially lower activities at other Cys-loop receptors. In an elaborate mutagenesis study of the 5-HT(3)A receptor guided by a homology model, PU02 is demonstrated to act through a transmembrane intersubunit site situated in the upper three helical turns of TM2 and TM3 in the (+)-subunit and TM1 and TM2 in the (-)-subunit. The Ser(248), Leu(288), Ile(290), Thr(294), and Gly(306) residues are identified as important molecular determinants of PU02 activity with minor contributions from Ser(292) and Val(310), and we propose that the naphthalene group of PU02 docks into the hydrophobic cavity formed by these. Interestingly, specific mutations of Ser(248), Thr(294), and Gly(306) convert PU02 into a complex modulator, potentiating and inhibiting 5-HT-evoked signaling through these mutants at low and high concentrations, respectively. The PU02 binding site in the 5-HT(3)R corresponds to allosteric sites in anionic Cys-loop receptors, which emphasizes the uniform nature of the molecular events underlying signaling through the receptors. Moreover, the dramatic changes in the functional properties of PU02 induced by subtle changes in its binding site bear witness to the delicate structural discrimination between allosteric inhibition and potentiation of Cys-loop receptors.

  11. Impact of intracellular domain flexibility upon properties of activated human 5-HT3 receptors*

    PubMed Central

    Kozuska, J L; Paulsen, I M; Belfield, W J; Martin, I L; Cole, D J; Holt, A; Dunn, S M J

    2014-01-01

    Background and Purpose It has been proposed that arginine residues lining the intracellular portals of the homomeric 5-HT3A receptor cause electrostatic repulsion of cation flow, accounting for a single-channel conductance substantially lower than that of the 5-HT3AB heteromer. However, comparison of receptor homology models for wild-type pentamers suggests that salt bridges in the intracellular domain of the homomer may impart structural rigidity, and we hypothesized that this rigidity could account for the low conductance. Experimental Approach Mutations were introduced into the portal region of the human 5-HT3A homopentamer, such that putative salt bridges were broken by neutralizing anionic partners. Single-channel and whole cell currents were measured in transfected tsA201 cells and in Xenopus oocytes respectively. Computational simulations of protein flexibility facilitated comparison of wild-type and mutant receptors. Key Results Single-channel conductance was increased substantially, often to wild-type heteromeric receptor values, in most 5-HT3A mutants. Conversely, introduction of arginine residues to the portal region of the heteromer, conjecturally creating salt bridges, decreased conductance. Gating kinetics varied significantly between different mutant receptors. EC50 values for whole-cell responses to 5-HT remained largely unchanged, but Hill coefficients for responses to 5-HT were usually significantly smaller in mutants. Computational simulations suggested increased flexibility throughout the protein structure as a consequence of mutations in the intracellular domain. Conclusions and Implications These data support a role for intracellular salt bridges in maintaining the quaternary structure of the 5-HT3 receptor and suggest a role for the intracellular domain in allosteric modulation of cooperativity and agonist efficacy. Linked Article This article is commented on by Vardy and Kenakin, pp. 1614–1616 of volume 171 issue 7. To view this commentary

  12. Mode of action of peppermint oil and (-)-menthol with respect to 5-HT3 receptor subtypes: binding studies, cation uptake by receptor channels and contraction of isolated rat ileum.

    PubMed

    Heimes, Katharina; Hauk, Florian; Verspohl, Eugen J

    2011-05-01

    Peppermint oil (Mentha × piperita L. (Lamiaceae) has been shown to exert potent antiemetic properties, but its mode of action has not yet been elucidated. Among its active constituents (-)-menthol is the most important. Three different in vitro models were used to investigate the effects on 5-HT(3) receptors (serotonin receptor subtype): [(14)C]guanidinium influx into N1E-115 cells which express 5-HT(3) receptors, isotonic contractions of the isolated rat ileum and equilibrium competition binding studies using a radioactively labelled 5-HT(3) receptor antagonist ([(3)H]GR65630) (3-(5-methyl-1H-imidazol-4-yl)-1-(1-methyl-1H-indol-3-yl)-1-propanone). Both peppermint oil and (-)-menthol inhibited [(14)C]guanidinium influx through 5-HT(3) receptor channels as well as contractions of the ileum induced by serotonin. Neither the peppermint oil nor (-)-menthol, however, was able to displace [(3)H]GR65630 from 5-HT(3) binding sites. It may be concluded that peppermint oil and (-)-menthol exert their antiemetic effect at least partly by acting on the 5-HT(3) receptor ion-channel complex, probably by binding to a modulatory site distinct from the serotonin binding site. Copyright © 2010 John Wiley & Sons, Ltd.

  13. Intrathecal nefopam-induced antinociception through activation of descending serotonergic projections involving spinal 5-HT7 but not 5-HT3 receptors.

    PubMed

    Lee, Hyung Gon; Kim, Woong Mo; Kim, Joung Min; Bae, Hong-Beom; Choi, Jeong Il

    2015-02-05

    We examined the involvement of spinal 5-HT(5-hydroxytryptamine) receptor 3(5-HT3R) and 7(5-HT7R) as well as the overall role of descending serotonergic projections in the analgesic effects of intrathecal(i.t.) nefopam for two rat models of formalin and paw incision test. I.t. nefopam produced an antinociceptive effect in a dose-dependent manner in both tests. Lesioning the spinal serotonergic projections using i.t. 5,7-dihydroxytryptamine(5,7-DHT) did not influence the intensity of allodynia in the paw incision test, but i.t. 5,7-DHT abolished the effect of nefopam. In the formain test, i.t. 5,7-DHT alone significantly diminished the flinches, but the effect of nefopam was not affected by i.t. 5,7-DHT. Antagonism study showed that i.t. 5-HT7R antagonist, SB269970 significantly blocked the antinociceptive effect of nefopam in both tests, but i.t. 5-HT3R antagonist, ondansetron has no influence on the effect of nefopam. The present study demonstrates that descending spinal serotonergic projections play a vital role in antinociceptive effect of i.t. nefopam in the paw incision test, but indeterminate in the formalin test. In both tests, the antinociceptive effect of i.t. nefopam involves the spinal 5-HT7R, but not 5-HT3R.

  14. Synthesis and biochemical evaluation of tritium-labeled 1-methyl-N-(8-methyl-8-azabicyclo(3. 2. 1)oct-3-yl)-1H-indazole-3-carboxa mide, a useful radioligand for 5HT3 receptors

    SciTech Connect

    Robertson, D.W.; Bloomquist, W.; Cohen, M.L.; Reid, L.R.; Schenck, K.; Wong, D.T. )

    1990-12-01

    The advent of potent, highly selective 5HT3 receptor antagonists has stimulated considerable interest in 5HT3 receptor mediated physiology and pharmacology. To permit detailed biochemical studies regarding interaction of the indazole class of serotonin (5HT) antagonists with 5HT3 receptors in multiple tissues, we synthesized 1-methyl-N-(8-methyl-8-azabicyclo(3.2.1)oct-3-yl)-1H-indazole- 3-carboxamide (LY278584, compound 9) in high specific activity, tritium-labeled form. This radioligand was selected as a synthetic target because of its potency as a 5HT3-receptor antagonist, its selectivity for this receptor viz a viz other 5HT-receptor subtypes, and the ability to readily incorporate three tritia via the indazole N-CH3 substituent. Alkylation of N-(8-methyl-8-azabicyclo(3.2.1)oct-3-yl)-1H-indazole-3-carboxamide (8) with sodium hydride and tritium-labeled iodomethane, followed by HPLC purification, resulted in (3H)-9 with a radiochemical purity of 99% and a specific activity of 80.5 Ci/mmol. This radioligand bound with high affinity to a single class of saturable recognition sites in membranes isolated from cerebral cortex of rat brain. The Kd was 0.69 nM and the Bmax was 16.9 fmol/mg of protein. The specific binding was excellent, and accounted for 83-93% of total binding at concentrations of 2 nM or less. The potencies of known 5HT3-receptor antagonists as inhibitors of (3H)-9 binding correlated well with their pharmacological receptor affinities as antagonists of 5HT-induced decreases in heart rate and contraction of guinea pig ileum, suggesting the central recognition site for this radioligand may be extremely similar to or identical with peripheral 5HT3 receptors.

  15. Tropisetron ameliorates early diabetic nephropathy in streptozotocin-induced diabetic rats.

    PubMed

    Barzegar-Fallah, Anita; Alimoradi, Houman; Asadi, Firouzeh; Dehpour, Ahmad Reza; Asgari, Mojgan; Shafiei, Massoumeh

    2015-04-01

    to be independent of the 5-HT3 receptor.

  16. Glucose-dependent trafficking of 5-HT3 receptors in rat gastrointestinal vagal afferent neurons

    PubMed Central

    Babic, Tanja; Troy, Amanda E; Fortna, Samuel R; Browning, Kirsteen N

    2012-01-01

    Background Intestinal glucose induces gastric relaxation via vagally mediated sensory-motor reflexes. Glucose can alter the activity of gastrointestinal (GI) vagal afferent (sensory) neurons directly, via closure of ATP-sensitive potassium channels, as well as indirectly, via the release of 5-hydroxytryptamine (5-HT) from mucosal enteroendocrine cells. We hypothesized that glucose may also be able to modulate the ability of GI vagal afferent neurons to respond to the released 5-HT, via regulation of neuronal 5-HT3 receptors. Methods Whole cell patch clamp recordings were made from acutely dissociated GI-projecting vagal afferent neurons exposed to equiosmolar Krebs’ solution containing different concentrations of D-glucose (1.25–20mM) and the response to picospritz application of 5-HT assessed. The distribution of 5-HT3 receptors in neurons exposed to different glucose concentrations was also assessed immunohistochemically. Key Results Increasing or decreasing extracellular D-glucose concentration increased or decreased, respectively, the 5-HT-induced inward current as well as the proportion of 5-HT3 receptors associated with the neuronal membrane. These responses were blocked by the Golgi-disrupting agent Brefeldin-A (5µM) suggesting involvement of a protein trafficking pathway. Furthermore, L-glucose did not mimic the response of D-glucose implying that metabolic events downstream of neuronal glucose uptake are required in order to observe the modulation of 5-HT3 receptor mediated responses. Conclusions & Inferences These results suggest that, in addition to inducing the release of 5-HT from enterochromaffin cells, glucose may also increase the ability of GI vagal sensory neurons to respond to the released 5-HT, providing a means by which the vagal afferent signal can be amplified or prolonged. PMID:22845622

  17. Tropisetron and its targets in Alzheimer's disease.

    PubMed

    Hashimoto, Kenji

    2015-01-01

    Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder. Despite this, there are no drugs for preventing the onset of AD. Preclinical studies suggest that the interaction between amyloid-β peptides (Aβ) and the α7 nicotinic acetylcholine receptor (α7 nAChR) plays a key role in AD pathology, and that α7 nAChR agonists could act as potential therapeutic drugs for AD. A recent study demonstrated that tropisetron, a potent α7 nAChR agonist and serotonin 5-hydroxytryptamine3 receptor antagonist, also bound to the ectodomain of amyloid precursor protein. Furthermore, tropisetron promoted greater improvements in memory than current AD therapeutic drugs, such as memantine and donepezil. Positron emission tomography studies detected Aβ deposition and inflammation in the brains of subjects with amnestic mild cognitive impairment (MCI) before the onset of AD. Given the role of α7 nAChR in Aβ deposition and inflammation, tropisetron represents an attractive potential therapeutic drug to delay or prevent MCI and AD. Additionally as this drug is used internationally to treat chemotherapy-induced emesis, its safety record is already known.

  18. The 5-HT3 receptor is essential for exercise-induced hippocampal neurogenesis and antidepressant effects.

    PubMed

    Kondo, M; Nakamura, Y; Ishida, Y; Shimada, S

    2015-11-01

    Exercise has a variety of beneficial effects on brain structure and function, such as hippocampal neurogenesis, mood and memory. Previous studies have shown that exercise enhances hippocampal neurogenesis, induces antidepressant effects and improves learning behavior. Brain serotonin (5-hydroxytryptamine, 5-HT) levels increase following exercise, and the 5-HT system has been suggested to have an important role in these exercise-induced neuronal effects. However, the precise mechanism remains unclear. In this study, analysis of the 5-HT type 3A receptor subunit-deficient (htr3a(-/-)) mice revealed that lack of the 5-HT type 3 (5-HT3) receptor resulted in loss of exercise-induced hippocampal neurogenesis and antidepressant effects, but not of learning enhancement. Furthermore, stimulation of the 5-HT3 receptor promoted neurogenesis. These findings demonstrate that the 5-HT3 receptor is the critical target of 5-HT action in the brain following exercise, and is indispensable for hippocampal neurogenesis and antidepressant effects induced by exercise. This is the first report of a pivotal 5-HT receptor subtype that has a fundamental role in exercise-induced morphological changes and psychological effects.

  19. Interaction of Pyridostigmine with the 5-HT(3) Receptor Antagonist Ondansetron in Guinea Pigs

    DTIC Science & Technology

    1993-05-13

    associated with other anti- emetic compounds such as metoclopramide (6). Pyridostigmine (PYR) has been utilized as the drug of choice for pretreatment...Naylor RJ, Richardson BP. 5-Hydroxytryptamine Receptor Antagonism by Metoclopramide and ICS 205- 930 in the Guinea-Pig Leads to Enhancement of

  20. Synergistic effect between prelimbic 5-HT3 and CB1 receptors on memory consolidation deficit in adult male Sprague-Dawley rats: An isobologram analysis.

    PubMed

    Ahmadi-Mahmoodabadi, N; Nasehi, M; Emam Ghoreishi, M; Zarrindast, M-R

    2016-03-11

    The serotonergic system has often been defined as a neuromodulator system, and is specifically involved in learning and memory via its various receptors. Serotonin is involved in many of the same processes affected by cannabinoids. The present study investigated the influence of bilateral post-training intra-prelimbic (PL) administrations of serotonergic 5-hydroxytryptamine type-3 (5-HT3) receptor agents on arachidonylcyclopropylamide (ACPA) (cannabinoid CB1 receptor agonist)-induced amnesia, using the step-through inhibitory avoidance (IA) task to assess memory in adult male Sprague-Dawley rats. The results indicated that sole intra-PL microinjection of ACPA (0.1 and 0.5 μg/rat) and 5-HT3 serotonin receptor agonist (m-Chlorophenylbiguanide hydrochloride, m-CPBG; 0.001, 0.01 and 0.1 μg/rat) impaired, whereas Y-25130 (a selective 5-HT3 serotonin receptor antagonist; 0.001 and 0.01 and 0.1 μg/rat) did not alter IA memory consolidation, by itself. Moreover, intra-PL administration of subthreshold dose of m-CPBG (0.0005 μg/rat) potentiated, while Y-25130 (0. 1 μg/rat) restored ACPA-induced memory consolidation deficit. The isobologram analysis showed that there is a synergistic effect between ACPA and m-CPBG on memory consolidation deficit. These findings suggest that 5-HT3 receptor mechanism(s), at least partly, play(s) a role in modulating the effect of ACPA on memory consolidation in the PL area.

  1. Synthesis and Pharmacological Evaluation of [(11)C]Granisetron and [(18)F]Fluoropalonosetron as PET Probes for 5-HT3 Receptor Imaging.

    PubMed

    Mu, Linjing; Müller Herde, Adrienne; Rüefli, Pascal M; Sladojevich, Filippo; Milicevic Sephton, Selena; Krämer, Stefanie D; Thompson, Andrew J; Schibli, Roger; Ametamey, Simon M; Lochner, Martin

    2016-11-16

    Serotonin-gated ionotropic 5-HT3 receptors are the major pharmacological targets for antiemetic compounds. Furthermore, they have become a focus for the treatment of irritable bowel syndrome (IBS) and there is some evidence that pharmacological modulation of 5-HT3 receptors might alleviate symptoms of other neurological disorders. Highly selective, high-affinity antagonists, such as granisetron (Kytril) and palonosetron (Aloxi), belong to a family of drugs (the "setrons") that are well established for clinical use. To enable us to better understand the actions of these drugs in vivo, we report the synthesis of 8-fluoropalonosetron (15) that has a binding affinity (Ki = 0.26 ± 0.05 nM) similar to the parent drug (Ki = 0.21 ± 0.03 nM). We radiolabeled 15 by nucleophilic (18)F-fluorination of an unsymmetrical diaryliodonium palonosetron precursor and achieved the radiosynthesis of 1-(methyl-(11)C)-N-granisetron ([(11)C]2) through N-alkylation with [(11)C]CH3I, respectively. Both compounds [(18)F]15 (chemical and radiochemical purity >95%, specific activity 41 GBq/μmol) and [(11)C]2 (chemical and radiochemical purity ≥99%, specific activity 170 GBq/μmol) were evaluated for their utility as positron emission tomography (PET) probes. Using mouse and rat brain slices, in vitro autoradiography with both [(18)F]15 and [(11)C]2 revealed a heterogeneous and displaceable binding in cortical and hippocampal regions that are known to express 5-HT3 receptors at significant levels. Subsequent PET experiments suggested that [(18)F]15 and [(11)C]2 are of limited utility for the PET imaging of brain 5-HT3 receptors in vivo.

  2. Wood creosote prevents CRF-induced motility via 5-HT3 receptors in proximal and 5-HT4 receptors in distal colon in rats.

    PubMed

    Ataka, Koji; Kuge, Tomoo; Fujino, Kazunori; Takahashi, Toku; Fujimiya, Mineko

    2007-05-30

    Wood creosote has been used as an herbal medicine against acute diarrhea caused by food poisoning and has an inhibitory effect on colonic motility and enterotoxin-induced ion secretion. Since no previous studies have examined the effects of wood creosote on stress-induced alteration of colonic motility, we examined the effects on the colonic motility altered by intracerebroventricular (i.c.v.) injection of corticotropin-releasing factor (CRF), which is a key mediator in responses to stress. We recorded motor activity in proximal and distal colon of unrestrained conscious rats via two manometory catheters. The frequencies of phase III-like contraction and the % motor indices in both proximal and distal colon were measured. At the same time the number of fecal pellets excreted was counted. I.c.v. injection of CRF increased the motor activity in both proximal and distal colon, and these effects were completely antagonized by i.c.v. injection of a selective CRF type 1 antagonist but not by a CRF type 2 antagonist. Changes in colonic motility induced by CRF were reversed by intravenously administered wood creosote. Intraluminal administration of the 5-HT(3) receptor antagonist granisetron, or the 5-HT(4) receptor antagonist SB 204070 blocked the increase in colonic motility induced by i.c.v. injection of CRF. Wood creosote prevented the increase in colonic motility induced by the 5-HT(3) receptor agonist SR57227A in the proximal colon, while it prevented the increase in colonic motility induced by the 5-HT(4) receptor agonist RS67506 in the distal colon. These results indicate that wood creosote prevents the increase in colonic motility induced by CRF via 5-HT(3) receptors in the proximal colon, and via 5-HT(4) receptors in the distal colon, suggesting that wood creosote might be useful to treat stress-induced diarrhea.

  3. Serotonin 5-HT3 Receptor-Mediated Vomiting Occurs via the Activation of Ca2+/CaMKII-Dependent ERK1/2 Signaling in the Least Shrew (Cryptotis parva)

    PubMed Central

    Zhong, Weixia; Hutchinson, Tarun E.; Chebolu, Seetha; Darmani, Nissar A.

    2014-01-01

    Stimulation of 5-HT3 receptors (5-HT3Rs) by 2-methylserotonin (2-Me-5-HT), a selective 5-HT3 receptor agonist, can induce vomiting. However, downstream signaling pathways for the induced emesis remain unknown. The 5-HT3R channel has high permeability to extracellular calcium (Ca2+) and upon stimulation allows increased Ca2+ influx. We examined the contribution of Ca2+/calmodulin-dependent protein kinase IIα (Ca2+/CaMKIIα), interaction of 5-HT3R with calmodulin, and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling to 2-Me-5-HT-induced emesis in the least shrew. Using fluo-4 AM dye, we found that 2-Me-5-HT augments intracellular Ca2+ levels in brainstem slices and that the selective 5-HT3R antagonist palonosetron, can abolish the induced Ca2+ signaling. Pre-treatment of shrews with either: i) amlodipine, an antagonist of L-type Ca2+ channels present on the cell membrane; ii) dantrolene, an inhibitor of ryanodine receptors (RyRs) Ca2+-release channels located on the endoplasmic reticulum (ER); iii) a combination of their less-effective doses; or iv) inhibitors of CaMKII (KN93) and ERK1/2 (PD98059); dose-dependently suppressed emesis caused by 2-Me-5-HT. Administration of 2-Me-5-HT also significantly: i) enhanced the interaction of 5-HT3R with calmodulin in the brainstem as revealed by immunoprecipitation, as well as their colocalization in the area postrema (brainstem) and small intestine by immunohistochemistry; and ii) activated CaMKIIα in brainstem and in isolated enterochromaffin cells of the small intestine as shown by Western blot and immunocytochemistry. These effects were suppressed by palonosetron. 2-Me-5-HT also activated ERK1/2 in brainstem, which was abrogated by palonosetron, KN93, PD98059, amlodipine, dantrolene, or a combination of amlodipine plus dantrolene. However, blockade of ER inositol-1, 4, 5-triphosphate receptors by 2-APB, had no significant effect on the discussed behavioral and biochemical parameters. This study demonstrates

  4. Serotonin 5-HT3 receptor-mediated vomiting occurs via the activation of Ca2+/CaMKII-dependent ERK1/2 signaling in the least shrew (Cryptotis parva).

    PubMed

    Zhong, Weixia; Hutchinson, Tarun E; Chebolu, Seetha; Darmani, Nissar A

    2014-01-01

    Stimulation of 5-HT3 receptors (5-HT3Rs) by 2-methylserotonin (2-Me-5-HT), a selective 5-HT3 receptor agonist, can induce vomiting. However, downstream signaling pathways for the induced emesis remain unknown. The 5-HT3R channel has high permeability to extracellular calcium (Ca(2+)) and upon stimulation allows increased Ca(2+) influx. We examined the contribution of Ca(2+)/calmodulin-dependent protein kinase IIα (Ca(2+)/CaMKIIα), interaction of 5-HT3R with calmodulin, and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling to 2-Me-5-HT-induced emesis in the least shrew. Using fluo-4 AM dye, we found that 2-Me-5-HT augments intracellular Ca(2+) levels in brainstem slices and that the selective 5-HT3R antagonist palonosetron, can abolish the induced Ca(2+) signaling. Pre-treatment of shrews with either: i) amlodipine, an antagonist of L-type Ca(2+) channels present on the cell membrane; ii) dantrolene, an inhibitor of ryanodine receptors (RyRs) Ca2+-release channels located on the endoplasmic reticulum (ER); iii) a combination of their less-effective doses; or iv) inhibitors of CaMKII (KN93) and ERK1/2 (PD98059); dose-dependently suppressed emesis caused by 2-Me-5-HT. Administration of 2-Me-5-HT also significantly: i) enhanced the interaction of 5-HT3R with calmodulin in the brainstem as revealed by immunoprecipitation, as well as their colocalization in the area postrema (brainstem) and small intestine by immunohistochemistry; and ii) activated CaMKIIα in brainstem and in isolated enterochromaffin cells of the small intestine as shown by Western blot and immunocytochemistry. These effects were suppressed by palonosetron. 2-Me-5-HT also activated ERK1/2 in brainstem, which was abrogated by palonosetron, KN93, PD98059, amlodipine, dantrolene, or a combination of amlodipine plus dantrolene. However, blockade of ER inositol-1, 4, 5-triphosphate receptors by 2-APB, had no significant effect on the discussed behavioral and biochemical parameters. This study

  5. Unraveling mechanisms underlying partial agonism in 5-HT3A receptors.

    PubMed

    Corradi, Jeremías; Bouzat, Cecilia

    2014-12-10

    Partial agonists have emerged as attractive therapeutic molecules. 2-Me-5HT and tryptamine have been defined as partial agonists of 5-HT3 receptors on the basis of macroscopic measurements. Because several mechanisms may limit maximal responses, we took advantage of the high-conductance form of the mouse serotonin type 3A (5-HT3A) receptor to understand their molecular actions. Individual 5-HT-bound receptors activate in long episodes of high open probability, consisting of groups of openings in quick succession. The activation pattern is similar for 2-Me-5HT only at very low concentrations since profound channel blockade takes place within the activating concentration range. In contrast, activation episodes are significantly briefer in the presence of tryptamine. Generation of a full activation scheme reveals that the fully occupied receptor overcomes transitions to closed preopen states (primed states) before opening. Reduced priming explains the partial agonism of tryptamine. In contrast, 2-Me-5HT is not a genuine partial agonist since priming is not dramatically affected and its low apparent efficacy is mainly due to channel blockade. The analysis also shows that the first priming step is the rate-limiting step and partial agonists require an increased number of priming steps for activation. Molecular docking suggests that interactions are similar for 5-HT and 2-Me-5HT but slightly different for tryptamine. Our study contributes to understanding 5-HT3A receptor activation, extends the novel concept of partial agonism within the Cys-loop family, reveals novel aspects of partial agonism, and unmasks molecular actions of classically defined partial agonists. Unraveling mechanisms underlying partial responses has implications in the design of therapeutic compounds.

  6. 5-HT3a Receptors Modulate Hippocampal Gamma Oscillations by Regulating Synchrony of Parvalbumin-Positive Interneurons.

    PubMed

    Huang, Ying; Yoon, Kristopher; Ko, Ho; Jiao, Song; Ito, Wataru; Wu, Jian-Young; Yung, Wing-Ho; Lu, Bai; Morozov, Alexei

    2016-02-01

    Gamma-frequency oscillatory activity plays an important role in information integration across brain areas. Disruption in gamma oscillations is implicated in cognitive impairments in psychiatric disorders, and 5-HT3 receptors (5-HT3Rs) are suggested as therapeutic targets for cognitive dysfunction in psychiatric disorders. Using a 5-HT3aR-EGFP transgenic mouse line and inducing gamma oscillations by carbachol in hippocampal slices, we show that activation of 5-HT3aRs, which are exclusively expressed in cholecystokinin (CCK)-containing interneurons, selectively suppressed and desynchronized firings in these interneurons by enhancing spike-frequency accommodation in a small conductance potassium (SK)-channel-dependent manner. Parvalbumin-positive interneurons therefore received diminished inhibitory input leading to increased but desynchronized firings of PV cells. As a consequence, the firing of pyramidal neurons was desynchronized and gamma oscillations were impaired. These effects were independent of 5-HT3aR-mediated CCK release. Our results therefore revealed an important role of 5-HT3aRs in gamma oscillations and identified a novel crosstalk among different types of interneurons for regulation of network oscillations. The functional link between 5-HT3aR and gamma oscillations may have implications for understanding the cognitive impairments in psychiatric disorders.

  7. Fluorophore assisted light inactivation (FALI) of recombinant 5-HT3A receptor constitutive internalization and function

    PubMed Central

    Morton, Russell A.; Luo, Guoxiang; Davis, Margaret I.; Hales, Tim G.; Lovinger, David M.

    2011-01-01

    Fluorescent proteins and molecules are now widely used to tag and visualize proteins resulting in an improved understanding of protein trafficking, localization, and function. In addition, fluorescent tags have also been used to inactivate protein function in a spatially and temporally-defined manner, using a technique known as fluorophore-assisted light inactivation (FALI) or chromophore-assisted light inactivation (CALI). In this study we tagged the serotonin3 A subunit with the α-bungarotoxin binding sequence (BBS) and subsequently labeled 5-HT3A/BBS receptors with fluorescently conjugated α-bungarotoxin in live cells. We show that 5-HT3A/BBS receptors are constitutively internalized in the absence of an agonist and internalization as well as receptor function are inhibited by fluorescence. The fluorescence-induced disruption of function and internalization was reduced with oxygen radical scavengers suggesting the involvement of reactive oxygen species, implicating the FALI process. Furthermore, these data suggest that intense illumination during live-cell microscopy may result in inadvertent FALI and inhibition of protein trafficking. PMID:21338684

  8. Serotonin enhances urinary bladder nociceptive processing via a 5-HT3 receptor mechanism.

    PubMed

    Hall, Jason D; DeWitte, Cary; Ness, Timothy J; Robbins, Meredith T

    2015-09-14

    Serotonin from the descending pain modulatory pathway is critical to nociceptive processing. Its effects on pain modulation may either be inhibitory or facilitatory, depending on the type of pain and which receptors are involved. Little is known about the role of serotonergic systems in bladder nociceptive processing. These studies examined the effect of systemic administration of the serotonin precursor, 5-hydroxytryptophan (5-HTP), on normal bladder and somatic sensation in rats. ELISA was used to quantify peripheral and central changes in serotonin and its major metabolite following 5-HTP administration, and the potential role of the 5-HT3 receptor on changes in bladder sensation elicited by 5-HTP was investigated. 5-HTP produced bladder hypersensitivity and somatic analgesia. The pro-nociceptive effect of 5-HTP was attenuated by intrathecal, but not systemic, ondansetron. Peripheral increases in serotonin, its metabolism and rate of turnover were detectable within 30min of 5-HTP administration. Significant enhancement of serotonin metabolism was observed centrally. These findings suggest that 5-HTP increases serotonin, which may then affect descending facilitatory systems to produce bladder hypersensitivity via activation of spinal 5-HT3 receptors. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  9. Open probability of homomeric murine 5-HT3A serotonin receptors depends on subunit occupancy

    PubMed Central

    Mott, David D; Erreger, Kevin; Banke, Tue G; Traynelis, Stephen F

    2001-01-01

    The time course of macroscopic current responses of homomeric murine serotonin 5-HT3A receptors was studied in whole cells and excised membrane patches under voltage clamp in response to rapid application of serotonin. Serotonin activated whole cell currents with an EC50 value for the peak response of 2 μm and a Hill slope of 3.0 (n = 12), suggesting that the binding of at least three agonist molecules is required to open the channel. Homomeric 5-HT3A receptors in excised membrane patches had a slow activation time course (mean ±s.e.m. 10-90 % rise time 12.5 ± 1.6 ms; n = 9 patches) for 100 μm serotonin. The apparent activation rate was estimated by fitting an exponential function to the rising phase of responses to supramaximal serotonin to be 136 s−1. The 5-HT3A receptor response to 100 μm serotonin in outside-out patches (n = 19) and whole cells (n = 41) desensitized with a variable rate that accelerated throughout the experiment. The time course for desensitization was described by two exponential components (for patches τslow 1006 ± 139 ms, amplitude 31 % τfast 176 ± 25 ms, amplitude 69 %). Deactivation of the response following serotonin removal from excised membrane patches (n = 8) and whole cells (n = 29) was described by a dual exponential time course with time constants similar to those for desensitization (for patches τslow 838 ± 217 ms, 55 % amplitude; τfast 213 ± 44 ms, 45 % amplitude). In most patches (6 of 8), the deactivation time course in response to a brief 1-5 ms pulse of serotonin was similar to or slower than desensitization. This suggests that the continued presence of agonist can induce desensitization with a similar or more rapid time course than agonist unbinding. The difference between the time course for deactivation and desensitization was voltage independent over the range -100 to -40 mV in patches (n = 4) and -100 to +50 mV in whole cells (n = 4), suggesting desensitization of these receptors in the presence of

  10. In silico investigation into the interactions between murine 5-HT3 receptor and the principle active compounds of ginger (Zingiber officinale).

    PubMed

    Lohning, Anna E; Marx, Wolfgang; Isenring, Liz

    2016-11-01

    Gingerols and shogaols are the primary non-volatile actives within ginger (Zingiber officinale). These compounds have demonstrated in vitro to exert 5-HT3 receptor antagonism which could benefit chemotherapy-induced nausea and vomiting (CINV). The site and mechanism of action by which these compounds interact with the 5-HT3 receptor is not fully understood although research indicates they may bind to a currently unidentified allosteric binding site. Using in silico techniques, such as molecular docking and GRID analysis, we have characterized the recently available murine 5-HT3 receptor by identifying sites of strong interaction with particular functional groups at both the orthogonal (serotonin) site and a proposed allosteric binding site situated at the interface between the transmembrane region and the extracellular domain. These were assessed concurrently with the top-scoring poses of the docked ligands and included key active gingerols, shogaols and dehydroshogaols as well as competitive antagonists (e.g. setron class of pharmacologically active drugs), serotonin and its structural analogues, curcumin and capsaicin, non-competitive antagonists and decoys. Unexpectedly, we found that the ginger compounds and their structural analogs generally outscored other ligands at both sites. Our results correlated well with previous site-directed mutagenesis studies in identifying key binding site residues. We have identified new residues important for binding the ginger compounds. Overall, the results suggest that the ginger compounds and their structural analogues possess a high binding affinity to both sites. Notwithstanding the limitations of such theoretical analyses, these results suggest that the ginger compounds could act both competitively or non-competitively as has been shown for palonosetron and other modulators of CYS loop receptors.

  11. Presynaptic 5-HT3 receptors evoke an excitatory response in dorsal vagal preganglionic neurones in anaesthetized rats

    PubMed Central

    Wang, Yun; Ramage, Andrew G; Jordan, David

    1998-01-01

    Recordings were made from a total of sixty-four vagal preganglionic neurones in the dorsal vagal motor nucleus (DVMN) of pentobarbitone sodium anaesthetized rats. The effects of ionophoretic administration of Mg2+ and Cd2+, inhibitors of neurotransmitter release, and the selective NMDA and non-NMDA receptor antagonists (±)-2-amino-5-phosphono-pentanoic acid (AP5) and 6,7-dinitroquinoxaline-2,3-dione (DNQX) on the excitatory actions of the 5-HT3 receptor agonist 1-phenylbiguanide (PBG) were studied. In extracellular recording experiments, PBG (0-40 nA) increased the firing rate of thirty-five of the thirty-nine neurones tested. The PBG-evoked excitation was attenuated by application of Mg2+ (1-10 nA) in sixteen of seventeen neurones or Cd2+ (2-10 nA) in seven of eight neurones tested. At these low ejection currents neither Mg2+ nor Cd2+ altered baseline firing rates and Mg2+ had no effect on the excitations evoked by DL-homocysteic acid (n = 4), NMDA (n = 4) or (AMPA; n = 2). Ionophoresis of AP5 (2-10 nA), at currents which selectively inhibited NMDA-evoked excitations, attenuated PBG-evoked excitations in all eight neurones tested. DNQX (5-20 nA), at currents which selectively inhibited AMPA-evoked excitations, also attenuated PBG-evoked excitations (n = 3). Intracellular activity was recorded in nine DVMN neurones. In six neurones ionophoretic application of PBG (10-200 nA) depolarized the membrane and increased firing rate whilst in the other three neurones, PBG had no effect on membrane potential though it increased synaptic noise (n = 3) and firing rate (n = 2). In all six neurones tested, ionophoresis of Mg2+ (10-120 nA) attenuated the PBG-evoked increases in synaptic noise and firing rate. In conclusion, the data are consistent with the hypothesis that 5-HT3 receptor agonists activate DVMN neurones partly by acting on receptors located at sites presynaptic to the neurones. Activation of these receptors appears to facilitate release of glutamate, which, in

  12. Vortioxetine dose-dependently reverses 5-HT depletion-induced deficits in spatial working and object recognition memory: a potential role for 5-HT1A receptor agonism and 5-HT3 receptor antagonism.

    PubMed

    du Jardin, Kristian Gaarn; Jensen, Jesper Bornø; Sanchez, Connie; Pehrson, Alan L

    2014-01-01

    We previously reported that the investigational multimodal antidepressant, vortioxetine, reversed 5-HT depletion-induced memory deficits while escitalopram and duloxetine did not. The present report studied the effects of vortioxetine and the potential impact of its 5-HT1A receptor agonist and 5-HT3 receptor antagonist properties on 5-HT depletion-induced memory deficits. Recognition and spatial working memory were assessed in the object recognition (OR) and Y-maze spontaneous alternation (SA) tests, respectively. 5-HT depletion was induced in female Long-Evans rats using 4-cholro-DL-phenylalanine methyl ester HCl (PCPA) and receptor occupancies were determined by ex vivo autoradiography. Rats were acutely dosed with vortioxetine, ondansetron (5-HT3 receptor antagonist) or flesinoxan (5-HT1A receptor agonist). The effects of chronic vortioxetine administration on 5-HT depletion-induced memory deficits were also assessed. 5-HT depletion reliably impaired memory performance in both the tests. Vortioxetine reversed PCPA-induced memory deficits dose-dependently with a minimal effective dose (MED) ≤0.1mg/kg (∼80% 5-HT3 receptor occupancy; OR) and ≤3.0mg/kg (5-HT1A, 5-HT1B, 5-HT3 receptor occupancy: ∼15%, 60%, 95%) in SA. Ondansetron exhibited a MED ≤3.0μg/kg (∼25% 5-HT3 receptor occupancy; OR), but was inactive in the SA test. Flesinoxan had a MED ≤1.0mg/kg (∼25% 5-HT1A receptor occupancy; SA); only 1.0mg/kg ameliorated deficits in the NOR. Chronic p.o. vortioxetine administration significantly improved memory performance in OR and occupied 95%, 66%, and 9.5% of 5-HT3, 5-HT1B, and 5-HT1A receptors, respectively. Vortioxetine's effects on SA performance may involve 5-HT1A receptor agonism, but not 5-HT3 receptor antagonism, whereas the effects on OR performance may involve 5-HT3 receptor antagonism and 5-HT1A receptor agonism. Copyright © 2013 Elsevier B.V. and ECNP. All rights reserved.

  13. On the voltage-dependent Ca2+ block of serotonin 5-HT3 receptors: a critical role of intracellular phosphates

    PubMed Central

    Noam, Yoav; Wadman, Wytse J; van Hooft, Johannes A

    2008-01-01

    Natively expressed serotonin 5-HT3 receptors typically possess a negative-slope conductance region in their I–V curve, due to a voltage-dependent block by external Ca2+ ions. However, in almost all studies performed with heterologously expressed 5-HT3 receptors, this feature was not observed. Here we show that mere addition of ATP to the pipette solution is sufficient to reliably observe a voltage-dependent block in homomeric (h5-HT3A) and heteromeric (h5-HT3AB) receptors expressed in HEK293 cells. A similar block was observed with a plethora of molecules containing a phosphate moiety, thus excluding a role of phosphorylation. A substitution of three arginines in the intracellular vestibule of 5-HT3A with their counterpart residues from the 5-HT3B subunit (RRR-QDA) was previously shown to dramatically increase single channel conductance. We find this mutant to have a linear I–V curve that is unaffected by the presence of ATP, with a fractional Ca2+ current (Pf%) that is reduced (1.8 ± 0.2%) compared to that of the homomeric receptor (4.1 ± 0.2%), and similar to that of the heteromeric form (2.0 ± 0.3%). Moreover, whereas ATP decreased the Pf% of the homomeric receptor, this was not observed with the RRR-QDA mutant. Finally, ATP was found to be critical for voltage-dependent channel block also in hippocampal interneurons that natively express 5-HT3 receptors. Taken together, our results indicate a novel mechanism by which ATP, and similar molecules, modulate 5-HT3 receptors via interactions with the intracellular vestibule of the receptor. PMID:18566001

  14. Spinal 5-HT1A, not the 5-HT1B or 5-HT3 receptors, mediates descending serotonergic inhibition for late-phase mechanical allodynia of carrageenan-induced peripheral inflammation.

    PubMed

    Kim, Joung Min; Jeong, Seong Wook; Yang, Jihoon; Lee, Seong Heon; Kim, Woon Mo; Jeong, Seongtae; Bae, Hong Beom; Yoon, Myung Ha; Choi, Jeong Il

    2015-07-23

    Previous electrophysiological studies demonstrated a limited role of 5-hydroxytryptamine 3 receptor (5-HT3R), but facilitatory role of 5-HT1AR and 5-HT1BR in spinal nociceptive processing of carrageenan-induced inflammatory pain. The release of spinal 5-HT was shown to peak in early-phase and return to baseline in late-phase of carrageenan inflammation. We examined the role of the descending serotonergic projections involving 5-HT1AR, 5-HT1BR, and 5-HT3R in mechanical allodynia of early- (first 4h) and late-phase (24h after) carrageenan-induced inflammation. Intrathecal administration of 5-HT produced a significant anti-allodynic effect in late-phase, but not in early-phase. Similarly, intrathecal 5-HT1AR agonist (8-OH-DPAT) attenuated the intensity of late-phase allodynia in a dose dependent fashion which was antagonized by 5-HT1AR antagonist (WAY-100635), but produced no effect on the early-phase allodynia. However, other agonists or antagonists of 5-HT1BR (CP-93129, SB-224289) and 5-HT3R (m-CPBG, ondansetron) did not produce any anti- or pro-allodynic effect in both early- and late- phase allodynia. These results suggest that spinal 5-HT1A, but not 5-HT1B or 5-HT3 receptors mediate descending serotonergic inhibition on nociceptive processing of late-phase mechanical allodynia in carrageenan-induced inflammation.

  15. On the role of brain 5-HT7 receptor in the mechanism of hypothermia: comparison with hypothermia mediated via 5-HT1A and 5-HT3 receptor.

    PubMed

    Naumenko, Vladimir S; Kondaurova, Elena M; Popova, Nina K

    2011-12-01

    Intracerebroventricular administration of selective agonist of serotonin 5-HT(7) receptor LP44 (4-[2-(methylthio)phenyl]-N-(1,2,3,4-tetrahydro-1-naphthalenyl)-1-pyperasinehexanamide hydrochloride; 10.3, 20.5 or 41.0 nmol) produced considerable hypothermic response in CBA/Lac mice. LP44-induced (20.5 nmol) hypothermia was significantly attenuated by the selective 5-HT(7) receptor antagonist SB 269970 (16.1 fmol, i.c.v.) pretreatment. At the same time, intraperitoneal administration of LP44 in a wide range of doses 1.0, 2.0 or 10.0 mg/kg (2.0, 4.0, 20.0 μmol/kg) did not cause considerable hypothermic response. These findings indicate the implication of central, rather than peripheral 5-HT(7) receptors in the regulation of hypothermia. The comparison of LP44-induced (20.5 nmol) hypothermic reaction in eight inbred mouse strains (DBA/2J, CBA/Lac, C57BL/6, BALB/c, ICR, AKR/J, C3H and Asn) was performed and a significant effect of genotype was found. In the same eight mouse strains, functional activity of 5-HT(1A) and 5-HT(3) receptors was studied. The comparison of hypothermic responses produced by 5-HT(7) receptor agonist LP44 (20.5 nmol, i.c.v.) and 5-HT(1A) receptor agonist 8-OH-DPAT 1.0 mg/kg, i.p. (3.0 μmol/kg), 5-HT(3) receptor agonist m-CPBG (40.0 nmol, i.c.v.) did not reveal considerable interstrain correlations between 5-HT(7) and 5-HT(1A) or 5-HT(3) receptor-induced hypothermia. The selective 5-HT(7) receptor antagonist SB 269970 (16.1 fmol, i.c.v.) failed to attenuate the hypothermic effect of 8-OH-DPAT 1.0 mg/kg, i.p. (3.0 μmol/kg) and m-CPBG (40.0 nmol, i.c.v.) indicating that the brain 5-HT(7) receptor is not involved in the hypothermic effects of 8-OH-DPAT or m-CPBG. The obtained results suggest that the central 5-HT(7) receptor plays an essential role in the mediation of thermoregulation independent of 5-HT(1A) and 5-HT(3) receptors.

  16. Involvement of 5-HT1, 5-HT2, and 5-HT3 receptors in the mediation of the prolactin response to serotonin and 5-hydroxytryptophan.

    PubMed

    Jørgensen, H; Knigge, U; Warberg, J

    1992-03-01

    Serotonin (5-HT) is involved in the neuroendocrine regulation of prolactin (PRL) secretion as a stimulator. Within the last decade several 5-HT receptor types have been identified, but their individual role in the mediation of the PRL response to 5-HT is only partly understood. We investigated in conscious male rats the effect of different 5-HT1, 5-HT2, and 5-HT3 receptor antagonists on the PRL response to 5-HT or to the 5-HT precursor 5-hydroxytrytophan (5-HTP) which was administered in combination with the 5-HT reuptake inhibitor fluoxetine. 5-HT (0.5-5.0 mg/kg BW i.v.) or 5-HTP (25-100 mg/kg i.p.) in combination with saline or fluoxetine (10 mg/kg i.p.) increased the plasma PRL concentration dose-dependently. Pretreatment with the 5-HT1+2 receptor antagonist methysergide (2.5 mg/kg i.p.) prevented the stimulatory effect of 5-HT or 5-HTP + fluoxetine. Pretreatment with the 5-HT2 receptor antagonists ketanserin or LY 53857 (2.5 mg/kg i.p.) inhibited the PRL response to 5-HT by approximately 80% and to 5-HTP + fluoxetine approximately 100%. A higher dose (10 mg/kg) of the 5-HT2 receptor antagonists possessed only 50% inhibitory effect. Pretreatment with the 5-HT3 receptor antagonists ICS 205-930 or GR 38032F (0.05-2.5 mg/kg i.p.) inhibited the PRL response induced by 5-HT or by 5-HTP + fluoxetine. The maximal inhibitory effect (approximately 80%) was obtained by a dose of 0.1 mg/kg of both compounds.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Ondansetron reverses anti-hypersensitivity from clonidine in rats following peripheral nerve injury: Role of γ-amino butyric acid in α2-adrenoceptor and 5-HT3 serotonin receptor analgesia

    PubMed Central

    Hayashida, Ken-ichiro; Kimura, Masafumi; Yoshizumi, Masaru; Hobo, Shotaro; Obata, Hideaki; Eisenach, James C.

    2012-01-01

    Introduction Monoaminergic pathways, impinging an α2-adrenoceptors and 5-HT3 serotonin receptors, modulate nociceptive transmission, but their mechanisms and interactions after neuropathic injury are unknown. Here we examine these interactions in rodents after nerve injury. Methods Male Sprague-Dawley rats following L5-L6 spinal nerve ligation (SNL) were used for either behavioral testing, in vivo microdialysis for γ-amino butyric acid (GABA) and acetylcholine release, or synaptosome preparation for GABA release. Results Intrathecal administration of the α2-adrenoceptor agonist (clonidine) and 5-HT3 receptor agonist (chlorophenylbiguanide) reduced hypersensitivity in SNL rats via GABA receptor-mediated mechanisms. Clonidine increased GABA and acetylcholine release in vivo in the spinal cord of SNL rats but not in normal rats. Clonidine-induced spinal GABA release in SNL rats was blocked by α2-adrenergic and nicotinic cholinergic antagonists. The 5-HT3 receptor antagonist ondansetron decreased and chlorophenylbiguanide increased spinal GABA release in both normal and SNL rats. In synaptosomes from the spinal dorsal horn of SNL rats, pre-synaptic GABA release was increased by nicotinic agonists and decreased by muscarinic and α2-adrenergic agonists. Spinally administered ondansetron significantly reduced clonidine-induced anti-hypersensitivity and spinal GABA release in SNL rats. Conclusion These results suggest that spinal GABA contributes to anti-hypersensitivity from intrathecal α2-adrenergic and 5-HT3 receptor agonists in the neuropathic pain state, that cholinergic neuroplasticity after nerve injury is critical for α2-adrenoceptor-mediated GABA release, and that blockade of spinal 5-HT3 receptors reduces α2-adrenoceptor-mediated anti-hypersensitivity via reducing total GABA release. PMID:22722575

  18. Functional evidence for the rapid desensitization of 5-HT(3) receptors on vagal afferents mediating the Bezold-Jarisch reflex

    NASA Technical Reports Server (NTRS)

    Whalen, E. J.; Johnson, A. K.; Lewis, S. J.

    2000-01-01

    The aim of this study was to determine whether 5-hydroxytryptamine (5-HT)(3) receptors on cardiopulmonary afferents mediating the Bezold-Jarisch reflex (BJR) desensitize upon repeated exposure to selective agonists. BJR-mediated falls in heart rate, diastolic arterial blood pressure and cardiac output elicited by the 5-HT(3)-receptor agonists, phenylbiguanide (100 microg/kg, i.v.) or 2-methyl-5-HT (100 microg/kg, i.v.), progressively diminished upon repeated injection in conscious rats. The BJR responses elicited by 5-HT (40 microg/kg, i.v.) were markedly reduced in rats which had received the above injections of phenylbiguanide or 2-methyl-5-HT whereas the BJR responses elicited by L-S-nitrosocysteine (10 micromol/kg, i.v.) were similar before and after the injections of the 5-HT(3) receptor agonists. These findings suggest that tachyphylaxis to 5-HT(3) receptor agonists may be due to the desensitization of 5-HT(3) receptors on cardiopulmonary afferents rather than the impairment of the central or peripheral processing of the BJR.

  19. Functional evidence for the rapid desensitization of 5-HT(3) receptors on vagal afferents mediating the Bezold-Jarisch reflex

    NASA Technical Reports Server (NTRS)

    Whalen, E. J.; Johnson, A. K.; Lewis, S. J.

    2000-01-01

    The aim of this study was to determine whether 5-hydroxytryptamine (5-HT)(3) receptors on cardiopulmonary afferents mediating the Bezold-Jarisch reflex (BJR) desensitize upon repeated exposure to selective agonists. BJR-mediated falls in heart rate, diastolic arterial blood pressure and cardiac output elicited by the 5-HT(3)-receptor agonists, phenylbiguanide (100 microg/kg, i.v.) or 2-methyl-5-HT (100 microg/kg, i.v.), progressively diminished upon repeated injection in conscious rats. The BJR responses elicited by 5-HT (40 microg/kg, i.v.) were markedly reduced in rats which had received the above injections of phenylbiguanide or 2-methyl-5-HT whereas the BJR responses elicited by L-S-nitrosocysteine (10 micromol/kg, i.v.) were similar before and after the injections of the 5-HT(3) receptor agonists. These findings suggest that tachyphylaxis to 5-HT(3) receptor agonists may be due to the desensitization of 5-HT(3) receptors on cardiopulmonary afferents rather than the impairment of the central or peripheral processing of the BJR.

  20. Spinal 5-HT2 and 5-HT3 receptors mediate low, but not high, frequency TENS-induced antihyperalgesia in rats

    PubMed Central

    Radhakrishnan, Rajan; King, Ellen W.; Dickman, Janelle K.; Herold, Carli A.; Johnston, Natalie F.; Spurgin, Megan L.; Sluka, Kathleen A.

    2009-01-01

    Transcutaneous electrical nerve stimulation (TENS) is a form of non-pharmacological treatment for pain. Involvement of descending inhibitory systems is implicated in TENS-induced analgesia. In the present study, the roles of spinal 5-HT and α2-adrenoceptors in TENS analgesia were investigated in rats. Hyperalgesia was induced by inflaming the knee joint with 3% kaolin—carrageenan mixture and assessed by measuring paw withdrawal latency (PWL) to heat before and 4 h after injection. The (1) α2-adrenergic antagonist yohimbine (30 μg), (2) 5-HT antagonist methysergide (5-HT1 and 5-HT2,30 μg), one of the 5-HT receptor subtype antagonists, (3) NAN-190 (5-HT1A, 15 μg), (4) ketanserin (5-HT2A, 30 μg), (5) MDL-72222 (5-HT3, 12 μg), or (6) vehicle was administered intrathecally prior to TENS treatment. Low (4 Hz) or high (100 Hz) frequency TENS at sensory intensity was then applied to the inflamed knee for 20 min and PWL was determined. Selectivity of the antagonists used was confirmed using respective agonists administered intrathecally. Yohimbine had no effect on the antihyperalgesia produced by low or high frequency TENS. Methysergide and MDL-72222 prevented the antihyperalgesia produced by low, but not high, frequency TENS. Ketanserin attenuated the antihyperalgesic effects of low frequency TENS whereas NAN-190 had no effect. The results from the present study show that spinal 5-HT receptors mediate low, but not high, frequency TENS-induced antihyperalgesia through activation of 5-HT2A and 5-HT3 receptors in rats. Furthermore, spinal noradrenergic receptors are not involved in either low or high frequency TENS antihyperalgesia. PMID:14499437

  1. Psychotropic and Nonpsychotropic Cannabis Derivatives Inhibit Human 5-HT3A receptors through a Receptor Desensitization-Dependent Mechanism

    PubMed Central

    Xiong, Wei; Koo, Bon-Nyeo; Morton, Russell; Zhang, Li

    2011-01-01

    Δ9 tetrahydrocannabinol (THC) and cannabidiol (CBD) are the principal psychoactive and non-psychoactive components of cannabis. While most THC-induced behavioral effects are thought to depend on endogenous cannabinoid 1 (CB1) receptors, the molecular targets for CBD remain unclear. Here, we report that CBD and THC inhibited the function of human 5-HT3A receptors (h5-HT3ARs) expressed in HEK 293 cells. The magnitude of THC and CBD inhibition was maximal 5 min after a continuous incubation with cannabinoids. The EC50 values for CBD and THC-induced inhibition were 110 nM and 322 nM respectively in HEK 293 cells expressing h5-HT3ARs. In these cells, CBD and THC did not stimulate specific [35S]-GTP-γs binding in membranes, suggesting that the inhibition by cannabinoids is unlikely mediated by a G-protein dependent mechanism. On the other hand, both CBD and THC accelerated receptor desensitization kinetics without significantly changing activation time. The extent of cannabinoid inhibition appeared to depend on receptor desensitization. Reducing receptor desensitization by nocodazole, 5-hydroxyindole and a point-mutation in the large cytoplasmic domain of the receptor significantly decreased CBD-induced inhibition. Similarly, the magnitude of THC and CBD-induced inhibition varied with the apparent desensitization rate of h5-HT3ARs expressed in Xenopus oocytes. For instance, with increasing amount of h5-HT3AR cRNA injected into the oocytes, the receptor desensitization rate at steady state decreased. THC and CBD-induced inhibition was correlated with the change in the receptor desensitization rate. Thus, CBD and THC inhibit h5-HT3A receptors through a mechanism that is dependent on receptor desensitization. PMID:21477640

  2. Subunit rotation models activation of serotonin 5-HT3AB receptors by agonists

    NASA Astrophysics Data System (ADS)

    Maksay, Gábor; Simonyi, Miklós; Bikádi, Zsolt

    2004-10-01

    The N-terminal extracellular regions of heterooligomeric 3AB-type human 5-hydroxytryptamine receptors (5-HT 3ABR) were modelled based on the crystal structure of snail acetylcholine binding protein AChBP. Stepwise rotation of subunit A by 5° was performed between -10° and 15° to mimic agonist binding and receptor activation. Anticlockwise rotation reduced the size of the binding cavity in interface AB and reorganised the network of hydrogen bonds along the interface. AB subunit dimers with different rotations were applied for docking of ligands with different efficacies: 5-HT, m-chlorophenylbiguanide, SR 57227, quinolinyl piperazine and lerisetron derivatives. All ligands were docked into the dimer with -10° rotation representing ligand-free, open binding cavities similarly, without pharmacological discrimination. Their ammonium ions were in hydrogen bonding distance to the backbone carbonyl of W183. Anticlockwise rotation and contraction of the binding cavity led to distinctive docking interactions of agonists with E129 and cation-π interactions of their ammonium ions. Side chains of several further amino acids participating in docking (Y143, Y153, Y234 and E236) are in agreement with the effects of point mutations in the binding loops. Our model postulates that 5-HT binds to W183 in a hydrophobic cleft as well as to E236 in a hydrophilic vestibule. Then it elicits anticlockwise rotation to draw in loop C via π-cation-π interactions of␣its ammonium ion with W183 and Y234. Finally, closure of the binding cavity might end in rebinding of 5-HT to E129 in the hydrophilic vestibule.

  3. Spinal 5-HT(3) receptor activation induces behavioral hypersensitivity via a neuronal-glial-neuronal signaling cascade.

    PubMed

    Gu, Ming; Miyoshi, Kan; Dubner, Ronald; Guo, Wei; Zou, Shiping; Ren, Ke; Noguchi, Koichi; Wei, Feng

    2011-09-07

    Recent studies indicate that the descending serotonin (5-HT) system from the rostral ventromedial medulla (RVM) in the brainstem and the 5-HT(3) receptor subtype in the spinal dorsal horn are involved in enhanced descending pain facilitation after tissue and nerve injury. However, the mechanisms underlying the activation of the 5-HT(3) receptor and its contribution to facilitation of pain remain unclear. In the present study, activation of spinal 5-HT(3) receptor by intrathecal injection of a selective 5-HT(3) receptor agonist, SR57227, induced spinal glial hyperactivity, neuronal hyperexcitability, and pain hypersensitivity in rats. We found that there was neuron-to-microglia signaling via chemokine fractalkine, microglia to astrocyte signaling via the cytokine IL-18, astrocyte to neuronal signaling by IL-1β, and enhanced activation of GluN (NMDA) receptors in the spinal dorsal horn. In addition, exogenous brain-derived neurotrophic factor-induced descending pain facilitation was accompanied by upregulation of CD11b and GFAP expression in the spinal dorsal horn after microinjection in the RVM, and these events were significantly prevented by functional blockade of spinal 5-HT(3) receptors. Enhanced expression of spinal CD11b and GFAP after hindpaw inflammation was also attenuated by molecular depletion of the descending 5-HT system by intra-RVM Tph-2 shRNA interference. Thus, these findings offer new insights into the cellular and molecular mechanisms at the spinal level responsible for descending 5-HT-mediated pain facilitation during the development of persistent pain after tissue and nerve injury. New pain therapies should focus on prime targets of descending facilitation-induced glial involvement, and in particular the blocking of intercellular signaling transduction between neuron and glia.

  4. Spinal 5-HT3 receptor activation induces behavioral hypersensitivity via a neuronal-glial-neuronal signaling cascade

    PubMed Central

    Gu, Ming; Miyoshi, Kan; Dubner, Ronald; Guo, Wei; Zou, Shiping; Ren, Ke; Noguchi, Koichi; Wei, Feng

    2011-01-01

    Recent studies indicate that the descending serotonin (5-HT) system from the rostral ventromedial medulla (RVM) in brainstem and the 5-HT3 receptor subtype in the spinal dorsal horn are involved in enhanced descending pain facilitation after tissue and nerve injury. However, the mechanisms underlying the activation of the 5-HT3 receptor and its contribution to facilitation of pain remain unclear. In the present study, activation of spinal 5-HT3 receptor by intrathecal injection of a selective 5-HT3 receptor agonist SR 57227 induced spinal glial hyperactivity, neuronal hyperexcitability and pain hypersensitivity in rats. We found that there was neuron-to-microglia signaling via chemokine fractalkine, microglia to astrocyte signaling via cytokine IL-18, astrocyte to neuronal signaling by IL-1β, and enhanced activation of GluN (NMDA) receptors in the spinal dorsal horn. In addition, exogenous BDNF-induced descending pain facilitation was accompanied with up-regulation of CD11b and GFAP expression in the spinal dorsal horn after microinjection in the RVM, which were significantly prevented by functional blockade of spinal 5-HT3 receptors. Enhanced expression of spinal CD11b and GFAP after hindpaw inflammation was also attenuated by molecular depletion of the descending 5-HT system by intra-RVM Tph-2 shRNA interference. Thus, these findings offer new insights into the cellular and molecular mechanisms at the spinal level responsible for descending 5-HT-mediated pain facilitation during the development of persistent pain after tissue and nerve injury. New pain therapies should focus on prime targets of descending facilitation-induced glial involvement, and in particular the blocking of intercellular signaling transduction between neuron and glia. PMID:21900561

  5. The N-methyl-D-aspartate receptor channel blockers memantine, MRZ 2/579 and other amino-alkyl-cyclohexanes antagonise 5-HT(3) receptor currents in cultured HEK-293 and N1E-115 cell systems in a non-competitive manner.

    PubMed

    Rammes, G; Rupprecht, R; Ferrari, U; Zieglgänsberger, W; Parsons, C G

    2001-06-22

    The type 3 serotonin (5-HT(3)) receptor is a ligand-gated ion channel. In concentration-clamp experiments, we investigated the effects of the uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonists memantine, amantadine and MRZ 2/579 on 5-HT receptors stabley expressed in HEK-293 cells and on native 5-HT(3) receptors in the N1E-115 cell line. All agents antagonized serotonin (10 microM)-induced inward currents with similar potency to that reported for NMDA receptors. This effect was characterized by inducing a pronounced receptor desensitization, and was probably non-competitive and voltage-independent. In contrast, (S)-ketamine was much weaker as an antagonist of 5-HT(3) receptors than NMDA receptors. Similar effects on 5-HT(3) receptors have been reported previously for a variety of anti-depressants and it is possible that the clinical anti-depressant effects reported for both memantine and amantadine are mediated, at least in part, by antagonistic effects at 5-HT(3) receptors.

  6. Dynamic Expression of Serotonin Receptor 5-HT3A in Developing Sensory Innervation of the Lower Urinary Tract

    PubMed Central

    Ritter, K. Elaine; Southard-Smith, E. Michelle

    2017-01-01

    Sensory afferent signaling is required for normal function of the lower urinary tract (LUT). Despite the wide prevalence of bladder dysfunction and pelvic pain syndromes, few effective treatment options are available. Serotonin receptor 5-HT3A is a known mediator of visceral afferent signaling and has been implicated in bladder function. However, basic expression patterns for this gene and others among developing bladder sensory afferents that could be used to inform regenerative efforts aimed at treating deficiencies in pelvic innervation are lacking. To gain greater insight into the molecular characteristics of bladder sensory innervation, we conducted a thorough characterization of Htr3a expression in developing and adult bladder-projecting lumbosacral dorsal root ganglia (DRG) neurons. Using a transgenic Htr3a-EGFP reporter mouse line, we identified 5-HT3A expression at 10 days post coitus (dpc) in neural crest derivatives and in 12 dpc lumbosacral DRG. Using immunohistochemical co-localization we observed Htr3a-EGFP expression in developing lumbosacral DRG that partially coincides with neuropeptides CGRP and Substance P and capsaicin receptor TRPV1. A majority of Htr3a-EGFP+ DRG neurons also express a marker of myelinated Aδ neurons, NF200. There was no co-localization of 5-HT3A with the TRPV4 receptor. We employed retrograde tracing in adult Htr3a-EGFP mice to quantify the contribution of 5-HT3A+ DRG neurons to bladder afferent innervation. We found that 5-HT3A is expressed in a substantial proportion of retrograde traced DRG neurons in both rostral (L1, L2) and caudal (L6, S1) axial levels that supply bladder innervation. Most bladder-projecting Htr3a-EGFP+ neurons that co-express CGRP, Substance P, or TRPV1 are found in L1, L2 DRG, whereas Htr3a-EGFP+, NF200+ bladder-projecting neurons are from the L6, S1 axial levels. Our findings contribute much needed information regarding the development of LUT innervation and highlight the 5-HT3A serotonin receptor as

  7. Anxiolytic-like effects observed in rats exposed to the elevated zero-maze following treatment with 5-HT2/5-HT3/5-HT4 ligands

    PubMed Central

    Bell, Rob; Duke, Aaron A.; Gilmore, Paula E.; Page, Deaglan; Bègue, Laurent

    2014-01-01

    The present study examined the effects of administering selective 5-HT antagonists and agonists to rats tested in the elevated zero-maze (EZM) model of anxiety. The EZM paradigm has advantages over the elevated plus-maze (EPM) paradigm with respect to measuring anxiety, yet has been utilized less frequently. Three experiments were conducted each with a diazepam control (0.25, 0.5 and 0.75 mg/kg). In the first experiment, we administered the 5-HT2C antagonist RS 102221 (0.5, 1.0, and 2.0 mg/kg) and 5-HT2C agonist MK-212 (0.25, 0.5 and 0.75 mg/kg); in the second experiment, we administered the 5-HT3 antagonist Y-25130 (0.1, 1.0 and 3.0 mg/kg) and 5-HT3 agonist SR 57227A (0.1, 1.0 and 3.0 mg/kg), and in the third experiment, we administered the 5-HT4 antagonist RS 39604 (0.01, 0.1, 1.0 mg/kg) and 5-HT4 agonist RS 67333 (0.01, 0.1 and 0.5 mg/kg). The administration of 5-HT2/3/4 subtype antagonists all generated behavioral profiles indicative of anxiolytic-like effects in the EZM, which was apparent from examination of both traditional and ethological measures. While little effect was observed from 5-HT2 and 5-HT3 agonists, the 5-HT4 agonist RS 67333 was found to produce a paradoxical anxiolytic-like effect similar to that produced by the 5-HT4 antagonist RS 39604. We conclude by discussing the implications of these findings. PMID:24457553

  8. Alpha-thujone reduces 5-HT3 receptor activity by an effect on the agonist-reduced desensitization.

    PubMed

    Deiml, T; Haseneder, R; Zieglgänsberger, W; Rammes, G; Eisensamer, B; Rupprecht, R; Hapfelmeier, G

    2004-02-01

    The convulsant effects of alpha-thujone, the psychotropic component of absinthe, were attributed to inhibitory actions at the GABAA receptor. Here, we investigated for the first time the 5-HT3 receptor as a potential site of the psychotropic actions of alpha-thujone. This cation permeable ligand-gated ion channel shows considerable homology to the GABAA receptor. We previously demonstrated that in homomeric assemblies of cloned human 5-HT,A receptor subunits. the endogenous agonist 5-HT induced desensitization via channel blockade. When the 5-HT3 B receptor subunit was co-expressed, the resulting heteromeric assemblies desensitized independent from channel blockade. In the present study, patch-clamp experiments revealed an inhibitory action of alpha-thujone on both homomeric and heteromeric 5-HT3 receptors. This inhibitory action was mediated via channel blockade. However, it was not alpha-thujone itself which blocked the channel. The present experiments suggested that, in homomeric receptors, alpha-thujone enhanced the inherent channel-blocking potency of the natural ligand. 5-HT. In heteromeric receptors, alpha-thujonerecruited an additional channel-blocking component of the agonist. By means of kinetic modeling, we simulated possible mechanisms by which alpha-thuljone decreased the 5-HT-induced responses. It is suggested that alpha-thujone reduced 5-HT3 receptor activity by an effect on mechanisms involved in receptor desensitization, which depend on receptor subunit composition. It remains to be shown if this inhibitory action on serotonergic responses contributes to behavioral effects of alpha-thujone.

  9. L-type calcium channels contribute to 5-HT3-receptor-evoked CaMKIIα and ERK activation and induction of emesis in the least shrew (Cryptotis parva).

    PubMed

    Hutchinson, Tarun E; Zhong, Weixia; Chebolu, Seetha; Wilson, Sean M; Darmani, Nissar A

    2015-05-15

    Activation of serotonergic 5-HT3 receptors by its selective agonist 2-methyl serotonin (2-Me-5-HT) induces vomiting, which is sensitive to selective antagonists of both 5-HT3 receptors (palonosetron) and L-type calcium channels (LTCC) (amlodipine or nifedipine). Previously we demonstrated that 5-HT3 receptor activation also causes increases in a palonosetron-sensitive manner in: i) intracellular Ca(2+) concentration, ii) attachment of calmodulin (CaM) to 5-HT3 receptor, and iii) phosphorylation of Ca(2+)/calmodulin-dependent protein kinase IIα (CaMKIIα) and extracellular-signal-regulated kinase 1/2 (ERK1/2). Here, we investigate the role of the short-acting LTCC blocker nifedipine on 2-Me-5-HT-evoked intracellular Ca(2+) increase and on downstream intracellular emetic signaling, which have been shown to be coupled with 2-Me-5-HT׳s emetic effects in the least shrew. Using the cell-permeant Ca(2+) indicator fluo-4 AM, here we present evidence for the contribution of Ca(2+) influx through LTCCs (sensitive to nifedipine) in 2-Me-5-HT (1µM) -evoked rise in cytosolic Ca(2+) levels in least shrew brainstem slices. Nifedipine pretreatment (10mg/kg, s.c.) also suppressed 2-Me-5-HT-evoked interaction of 5-HT3 receptors with CaM as well as phosphorylation of CaMKIIα and ERK1/2 in the least shrew brainstem, and 5-HT3 receptors -CaM colocalization in jejunum of the small intestine. In vitro exposure of isolated enterochromaffin cells of the small intestine to 2-Me-5-HT (1µM) caused CaMKIIα phosphorylation, which was also abrogated by nifedipine pretreatment (0.1µM). In addition, pretreatment with the CaMKII inhibitor KN62 (10mg/kg, i.p.) suppressed emesis and also the activation of CaMKIIα, and ERK in brainstem caused by 2-Me-5-HT (5mg/kg, i.p.). This study provides further mechanistic explanation for our published findings that nifedipine can dose-dependently protect shrews from 2-Me-5-HT-induced vomiting.

  10. 5-Hydroxytryptamine (5-HT) Cellular Sequestration during Chronic Exposure Delays 5-HT3 Receptor Resensitization due to Its Subsequent Release*

    PubMed Central

    Hothersall, J. Daniel; Alexander, Amy; Samson, Andrew J.; Moffat, Christopher; Bollan, Karen A.; Connolly, Christopher N.

    2014-01-01

    The serotonergic synapse is dynamically regulated by serotonin (5-hydroxytryptamine (5-HT)) with elevated levels leading to the down-regulation of the serotonin transporter and a variety of 5-HT receptors, including the 5-HT type-3 (5-HT3) receptors. We report that recombinantly expressed 5-HT3 receptor binding sites are reduced by chronic exposure to 5-HT (IC50 of 154.0 ± 45.7 μm, t½ = 28.6 min). This is confirmed for 5-HT3 receptor-induced contractions in the guinea pig ileum, which are down-regulated after chronic, but not acute, exposure to 5-HT. The loss of receptor function does not involve endocytosis, and surface receptor levels are unaltered. The rate and extent of down-regulation is potentiated by serotonin transporter function (IC50 of 2.3 ± 1.0 μm, t½ = 3.4 min). Interestingly, the level of 5-HT uptake correlates with the extent of down-regulation. Using TX-114 extraction, we find that accumulated 5-HT remains soluble and not membrane-bound. This cytoplasmically sequestered 5-HT is readily releasable from both COS-7 cells and the guinea pig ileum. Moreover, the 5-HT level released is sufficient to prevent recovery from receptor desensitization in the guinea pig ileum. Together, these findings suggest the existence of a novel mechanism of down-regulation where the chronic release of sequestered 5-HT prolongs receptor desensitization. PMID:25281748

  11. Inhibitory effects of dextrorotatory morphinans on the human 5-HT(3A) receptor expressed in Xenopus oocytes: Involvement of the N-terminal domain of the 5-HT(3A) receptor.

    PubMed

    Lee, Byung-Hwan; Hwang, Sung-Hee; Choi, Sun-Hye; Shin, Tae-Joon; Kang, Jiyeon; Kim, Hyun-Joong; Kim, Hyoung-Chun; Lee, Joon-Hee; Nah, Seung-Yeol

    2012-07-05

    We previously developed a series of dextromethorphan (DM, 3-methoxy-17-methylmorphinan) analogs modified at positions 3 and 17 of the morphinan ring system. Recent reports have shown that DM attenuates abdominal pain caused by irritable bowel syndrome, and multidrug regimens that include DM prevent nausea/vomiting following cancer surgery. However, little is known regarding the molecular mechanisms underlying the beneficial effects of DM. Here, we investigated the effects of DM, 3 of its analogs (AM, 3-allyloxy-17-methoxymorphian; CM, 3-cyclopropyl-17-methoxymorphinan; and DF, 3-methyl-17-methylmorphinan), and 1 of its metabolites (HM, 3-methoxymorphinan) on the activity of the human 5-HT(3A) receptor channel expressed in Xenopus laevis oocytes, using the 2-microelectrode voltage clamp technique. We found that intra-oocyte injection of human 5-HT(3A) receptor cRNAs elicited an inward current (I(5-HT)) in the presence of 5-HT. Cotreatment with AM, CM, DF, DM, or HM inhibited I(5-HT) in a dose-dependent, voltage-independent, and reversible manner. The IC(50) values for AM, CM, DF, DM, and HM were 24.5±1.4, 21.5±4.2, 132.6±35.8, 181.3±23.5, and 191.3±31.5μM, respectively. The IC(50) values of AM and CM were 7-fold lower than that of DM, and mechanistic analysis revealed that DM, DF, HM, AM, and CM were competitive inhibitors of I(5-HT). Point mutations of Arg241 in the N-terminal, but not amino acids in the pore region, to other amino acid residues attenuated or abolished DM- and DM-analog-induced inhibition of I(5-HT). Together, these results demonstrated that dextrorotatory morphinans might regulate 5-HT(3A) receptor channel activity via interaction with its N-terminal domain.

  12. Noncompetitive Inhibition of 5-HT3 Receptors by Citral, Linalool, and Eucalyptol Revealed by Nonlinear Mixed-Effects Modeling.

    PubMed

    Jarvis, Gavin E; Barbosa, Roseli; Thompson, Andrew J

    2016-03-01

    Citral, eucalyptol, and linalool are widely used as flavorings, fragrances, and cosmetics. Here, we examined their effects on electrophysiological and binding properties of human 5-HT3 receptors expressed in Xenopus oocytes and human embryonic kidney 293 cells, respectively. Data were analyzed using nonlinear mixed-effects modeling to account for random variance in the peak current response between oocytes. The oils caused an insurmountable inhibition of 5-HT-evoked currents (citral IC50 = 120 µM; eucalyptol = 258 µM; linalool = 141 µM) and did not compete with fluorescently labeled granisetron, suggesting a noncompetitive mechanism of action. Inhibition was not use-dependent but required a 30-second preapplication. Compound washout caused a slow (∼180 seconds) but complete recovery. Coapplication of the oils with bilobalide or diltiazem indicated they did not bind at the same locations as these channel blockers. Homology modeling and ligand docking predicted binding to a transmembrane cavity at the interface of adjacent subunits. Liquid chromatography coupled to mass spectrometry showed that an essential oil extracted from Lippia alba contained 75.9% citral. This inhibited expressed 5-HT3 receptors (IC50 = 45 µg ml(-1)) and smooth muscle contractions in rat trachea (IC50 = 200 µg ml(-1)) and guinea pig ileum (IC50 = 20 µg ml(-1)), providing a possible mechanistic explanation for why this oil has been used to treat gastrointestinal and respiratory ailments. These results demonstrate that citral, eucalyptol, and linalool inhibit 5-HT3 receptors, and their binding to a conserved cavity suggests a valuable target for novel allosteric modulators.

  13. Evidence for the involvement of the serotonergic 5-HT2A/C and 5-HT3 receptors in the antidepressant-like effect caused by oral administration of bis selenide in mice.

    PubMed

    Jesse, Cristiano R; Wilhelm, Ethel A; Bortolatto, Cristiani F; Nogueira, Cristina W

    2010-03-17

    The present study investigated a possible antidepressant-like activity of bis selenide using two predictive tests for antidepressant effect on rodents: the forced swimming test (FST) and the tail suspension test (TST). Bis selenide (0.5-5 mg/kg, p.o.) decreased the immobility time in the mouse FST and TST. The anti-immobility effect of bis selenide (1 mg/kg, p.o.) in the TST was prevented by the pretreatment of mice with p-chlorophenylalanine methyl ester (PCPA; 100 mg/kg, i.p., an inhibitor of serotonin synthesis), ketanserin (1 mg/kg, i.p., a 5-HT(2A/2C) receptor antagonist), and ondasentron (1 mg/kg, i.p., a 5-HT(3) receptor antagonist). Pretreatment of mice with prazosin (1 mg/kg, i.p., an alpha(1)-adrenoceptor antagonist), yohimbine (1 mg/kg, i.p., an alpha(2)-adrenoceptor antagonist), propranolol (2 mg/kg, i.p., a beta-adrenoceptor antagonist), SCH23390 (0.05 mg/kg, s.c., a dopamine D(1) receptor antagonist), sulpiride (50 mg/kg, i.p., a dopamine D(2) receptor antagonist), or WAY 100635 (0.1 mg/kg, s.c., a selective 5-HT(1A) receptor antagonist) did not block the antidepressant-like effect of bis selenide (1 mg/kg, p.o.) in the TST. Administration of bis selenide (0.1 mg/kg, p.o.) and fluoxetine (1 mg/kg), at subeffective doses, produced an antidepressant-like effect in the TST. Bis selenide did not alter Na(+) K(+) ATPase, MAO-A and MAO-B activities in whole brains of mice. Bis selenide produced an antidepressant-like effect in the mouse TST and FST, which may be related to the serotonergic system (5-HT(2A/2C) and 5-HT(3) receptors).

  14. Transcriptomic and anatomic parcellation of 5-HT3AR expressing cortical interneuron subtypes revealed by single-cell RNA sequencing

    PubMed Central

    Frazer, Sarah; Prados, Julien; Niquille, Mathieu; Cadilhac, Christelle; Markopoulos, Foivos; Gomez, Lucia; Tomasello, Ugo; Telley, Ludovic; Holtmaat, Anthony; Jabaudon, Denis; Dayer, Alexandre

    2017-01-01

    Cortical GABAergic interneurons constitute a highly diverse population of inhibitory neurons that are key regulators of cortical microcircuit function. An important and heterogeneous group of cortical interneurons specifically expresses the serotonin receptor 3A (5-HT3AR) but how this diversity emerges during development is poorly understood. Here we use single-cell transcriptomics to identify gene expression patterns operating in Htr3a-GFP+ interneurons during early steps of cortical circuit assembly. We identify three main molecular types of Htr3a-GFP+ interneurons, each displaying distinct developmental dynamics of gene expression. The transcription factor Meis2 is specifically enriched in a type of Htr3a-GFP+ interneurons largely confined to the cortical white matter. These MEIS2-expressing interneurons appear to originate from a restricted region located at the embryonic pallial–subpallial boundary. Overall, this study identifies MEIS2 as a subclass-specific marker for 5-HT3AR-containing interstitial interneurons and demonstrates that the transcriptional and anatomical parcellation of cortical interneurons is developmentally coupled. PMID:28134272

  15. Comparative safety and effectiveness of serotonin receptor antagonists in patients undergoing chemotherapy: a systematic review and network meta-analysis.

    PubMed

    Tricco, Andrea C; Blondal, Erik; Veroniki, Areti Angeliki; Soobiah, Charlene; Vafaei, Afshin; Ivory, John; Strifler, Lisa; Cardoso, Roberta; Reynen, Emily; Nincic, Vera; Ashoor, Huda; Ho, Joanne; Ng, Carmen; Johnson, Christy; Lillie, Erin; Antony, Jesmin; Roberts, Derek J; Hemmelgarn, Brenda R; Straus, Sharon E

    2016-12-23

    Although serotonin (5-HT3) receptor antagonists are effective in reducing nausea and vomiting, they may be associated with increased cardiac risk. Our objective was to examine the comparative safety and effectiveness of 5-HT3 receptor antagonists (e.g., dolasetron, granisetron, ondansetron, palonosetron, tropisetron) alone or combined with steroids for patients undergoing chemotherapy. We searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials from inception until December 2015 for studies comparing 5-HT3 receptor antagonists with each other or placebo in chemotherapy patients. The search results were screened, data were abstracted, and risk of bias was appraised by pairs of reviewers, independently. Random-effects meta-analyses and network meta-analyses (NMAs) were conducted. After screening 9226 citations and 970 full-text articles, we included 299 studies (n = 58,412 patients). None of the included studies reported harms for active treatment versus placebo. For NMAs on the risk of arrhythmia (primary outcome; three randomized controlled trials [RCTs], 627 adults) and mortality (secondary outcome; eight RCTs, 4823 adults), no statistically significant differences were observed between agents. A NMA on the risk of QTc prolongation showed a significantly greater risk for dolasetron + dexamethasone versus ondansetron + dexamethasone (four RCTs, 3358 children and adults, odds ratio 2.94, 95% confidence interval 2.13-4.17). For NMAs on the number of patients without nausea (44 RCTs, 11,664 adults, 12 treatments), number of patients without vomiting (63 RCTs, 15,460 adults, 12 treatments), and number of patients without chemotherapy-induced nausea or vomiting (27 RCTs, 10,924 adults, nine treatments), all agents were significantly superior to placebo. For a NMA on severe vomiting (10 RCTs, 917 adults), all treatments decreased the risk, but only ondansetron and ramosetron were significantly superior to placebo. According to a rank

  16. Interactions of metoclopramide and ergotamine with human 5-HT3A receptors and human 5-HT reuptake carriers

    PubMed Central

    Walkembach, Jan; Brüss, Michael; Urban, Bernd W; Barann, Martin

    2005-01-01

    The actions of metoclopramide and ergotamine, drugs which are used as a combined migraine medication, on human (h)5-HT3A receptors and 5-HT reuptake carriers, stably expressed in HEK-293 cells, were studied with patch-clamp- and ([3H]5-HT)-uptake techniques. At clinical concentrations, metoclopramide inhibited peak and integrated currents through h5-HT3A receptors concentration-dependently (IC50=0.064 and 0.076 μM, respectively) when it was applied in equilibrium (60 s before and during 5-HT (30 μM) exposure). The onset and offset time constants of metoclopramide action were 1.3 and 2.1 s, respectively. The potency of metoclopramide when exclusively applied during the agonist pulse decreased more than 200-fold (IC50=19.0 μM, peak current suppression). Metoclopramide (0.10 μM) did not alter the EC50 of 5-HT-induced peak currents. In contrast to the lack of competitive interaction between metoclopramide and 5-HT in this functional assay, metoclopramide inhibited specific [3H]GR65630 binding to human h5-HT3A receptors in a surmountable manner. This seeming discrepancy between functional studies and radioligand binding experiments may be accounted for by (1) the slow kinetics of inhibition of peak currents by metoclopramide compared with the fast onset and offset kinetics of 5-HT-induced currents and (2) the low efficacy of metoclopramide in inhibiting radioligand binding (e.g. only 20% binding inhibition compared to 79% peak current suppression by 200 nM metoclopramide). At low concentrations (1–10 nM), ergotamine had no effect on 5-HT (30 μM)-induced peak currents. Above clinical concentrations, ergotamine (>3 μM) inhibited them. When both drugs were applied together (0.10 μM metoclopramide+0.001 to 0.01 μM ergotamine), an inhibition of both, peak and integrated current responses was observed. Neither metoclopramide (⩽30 μM) nor ergotamine (⩽30 μM) had an effect on the 5-HT reuptake carrier as they did not alter the

  17. Investigation of 5-HT3A receptor gene expression in peripheral blood mononuclear cells of individuals who had been exposed to air pollution.

    PubMed

    Ahangari, Ghasem; Amirabad, Leila Mohammadi; Mozafari, Sona; Majeidi, Ali; Deilami, Gholamreza Derkhshan

    2013-12-01

    The role of air pollution in exacerbation of allergic symptoms is well known. Several studies have shown the effect of air pollution on serotonergic system. The changes in serotonergic system could trigger several allergic symptoms. 5-HT(3A) is among serotonin receptors on the peripheral Blood Mononuclear Cells (PBMCs) as well as other cells. In the present study we compared the 5-HT(3A) gene expression in PBMCs of the asthmatic patients as well as individuals who had been exposed to the air pollution. Normal individuals were also included in the study as control for comparison of 5-HT(3A) gene expression. Following the synthesis of the cDNA using mRNA extracted from PBMCs the level of 5- HT(3A) gene expression was measured using real-time PCR. The results showed t a significant increase in the relative expression level of 5-HT(3A) receptor in PBMCs from asthmatic patients and individuals exposed to the air pollutants compared to normal controls. Our result indicates that significant increase in 5-HT(3A) receptor may contribute to the pathogenesis as well as allergic symptoms which resulted from air pollution.

  18. Dual role of serotonin in the pathogenesis of indomethacin-induced small intestinal ulceration: pro-ulcerogenic action via 5-HT3 receptors and anti-ulcerogenic action via 5-HT4 receptors.

    PubMed

    Kato, Shinichi; Matsuda, Narumi; Matsumoto, Kenjiro; Wada, Mai; Onimaru, Naoki; Yasuda, Masashi; Amagase, Kikuko; Horie, Syunji; Takeuchi, Koji

    2012-09-01

    Serotonin (5-HT) exerts multiple physiological functions not only in the central and peripheral nervous systems but also in the gastrointestinal tract, and these multiple functions are accounted for by a variety of 5-HT receptor subtypes. We investigated the role of 5-HT in the pathogenesis of indomethacin-induced intestinal lesions in mice, in relation to 5-HT receptor subtypes. A single oral administration of indomethacin (10 mg/kg) provoked damage in the small intestine of mice 24 h later, and this response was prevented by pretreatment with p-chlorophenylalanine (a 5-HT synthesis inhibitor). The administration of 5-HT3 receptor antagonists, such as ondansetron and ramosetron, dose-dependently reduced the severity of the intestinal lesions, whereas a high dose of GR113808 (a 5-HT4 receptor antagonist) significantly aggravated these lesions. In contrast, NAN-190 (a 5-HT1 receptor antagonist), ketanserin (a 5-HT2 receptor antagonist), and SB269970 (a 5-HT7 receptor antagonist) had no effect on these lesions. Mosapride (a 5-HT4 receptor agonist) significantly reduced the severity of indomethacin-induced intestinal lesions, and this protective effect was totally prevented by either GR113808 or methyllycaconitine (an α7-nicotinic acetylcholine receptor antagonist). Indomethacin increased the activity of myeloperoxidase and the expression of inducible nitric oxide synthase, inflammatory cytokines, and chemokines in the small intestine; these responses were significantly attenuated by ondansetron and mosapride. These findings suggest that endogenous 5-HT exerts a dual role in the pathogenesis of indomethacin-induced intestinal lesions: pro-ulcerogenic action via 5-HT3 receptors and anti-ulcerogenic action via 5-HT4 receptors, and the latter effect via 5-HT4 receptors may be mediated by activation of α7-nicotinic acetylcholine receptors.

  19. Noncompetitive Inhibition of 5-HT3 Receptors by Citral, Linalool, and Eucalyptol Revealed by Nonlinear Mixed-Effects Modeling

    PubMed Central

    Jarvis, Gavin E.; Barbosa, Roseli

    2016-01-01

    Citral, eucalyptol, and linalool are widely used as flavorings, fragrances, and cosmetics. Here, we examined their effects on electrophysiological and binding properties of human 5-HT3 receptors expressed in Xenopus oocytes and human embryonic kidney 293 cells, respectively. Data were analyzed using nonlinear mixed-effects modeling to account for random variance in the peak current response between oocytes. The oils caused an insurmountable inhibition of 5‐HT–evoked currents (citral IC50 = 120 µM; eucalyptol = 258 µM; linalool = 141 µM) and did not compete with fluorescently labeled granisetron, suggesting a noncompetitive mechanism of action. Inhibition was not use‐dependent but required a 30-second preapplication. Compound washout caused a slow (∼180 seconds) but complete recovery. Coapplication of the oils with bilobalide or diltiazem indicated they did not bind at the same locations as these channel blockers. Homology modeling and ligand docking predicted binding to a transmembrane cavity at the interface of adjacent subunits. Liquid chromatography coupled to mass spectrometry showed that an essential oil extracted from Lippia alba contained 75.9% citral. This inhibited expressed 5‐HT3 receptors (IC50 = 45 µg ml−1) and smooth muscle contractions in rat trachea (IC50 = 200 µg ml−1) and guinea pig ileum (IC50 = 20 µg ml−1), providing a possible mechanistic explanation for why this oil has been used to treat gastrointestinal and respiratory ailments. These results demonstrate that citral, eucalyptol, and linalool inhibit 5-HT3 receptors, and their binding to a conserved cavity suggests a valuable target for novel allosteric modulators. PMID:26669427

  20. Review: 5-Ht1, 5-Ht2, 5-Ht3, And 5-Ht7 Receptors And Their Role In The Modulation Of Pain Response In The Central Nervous System.

    PubMed

    Cortes-Altamirano, José Luis; Olmos-Hernández, Adriana; Bonilla-Jaime, Herlinda; Carrillo-Mora, Paul; Bandala, Cindy; Reyes-Long, S; Alfaro-Rodríguez, Alfonso

    2017-09-11

    The aim of this review was to identify the mechanisms by which serotonin receptors involved at the central level are able to modulate the nociceptive response. Pain is a defense mechanism of the body that entails physiological, anatomical, neurochemical, and psychological changes, and is defined as an unpleasant sensory and emotional experience with potential risk of tissue damage, comprising the leading cause of appointments with Physicians worldwide. Treatment for this symptom has generated several neuropharmacological lines of research, due to the different types of pain and the various drugs employed to treat this condition. Serotonin [5-HydroxyTryptamine (5-HT)] is a neurotransmitter with seven families (5-HT1–5-HT7) and approximately 15 receptor subtypes. Serotonin modulates neuronal activity; however, this neurotransmitter is related with a number of physiological processes, such as cardiovascular function, gastric motility, renal function, etc. On the other hand, several researches reported that serotonin modulates nociceptive response through 5-HT1, 5-HT2, 5-HT3, and 5-HT7 receptors in the Central Nervous System (CNS). In this review, a search was conducted on PubMed, ProQuest, EBSCO, and the Science Citation Index for studies evaluating the effects of 5-HT1, 5-HT2, 5-HT3, and 5-HT7 receptors in the CNS on the modulation of different types of pain. Conclusions We concluded that 5-HT1, 5-HT2, 5-HT3, and 5-HT7 receptors in the CNS modulate the pain, but this depends on the distribution of the receptors, dose of agonists or antagonists, administration route, pain type and duration to order to inhibit, to excite, or even maintain the nociceptive response. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  1. Contribution of Hippocampal 5-HT3 Receptors in Hippocampal Autophagy and Extinction of Conditioned Fear Responses after a Single Prolonged Stress Exposure in Rats.

    PubMed

    Wu, Zhong-Min; Yang, Li-Hua; Cui, Rong; Ni, Gui-Lian; Wu, Feng-Tian; Liang, Yong

    2017-05-01

    One of the hypotheses about the pathogenesis of posttraumatic stress disorder (PTSD) is the dysfunction of serotonin (5-HT) neurotransmission. While certain 5-HT receptor subtypes are likely critical for the symptoms of PTSD, few studies have examined the role of 5-HT3 receptor in the development of PTSD, even though 5-HT3 receptor is critical for contextual fear extinction and anxiety-like behavior. Therefore, we hypothesized that stimulation of 5-HT3 receptor in the dorsal hippocampus (DH) could prevent hippocampal autophagy and the development of PTSD-like behavior in animals. To this end, we infused SR57227, selective 5-HT3 agonist, into the DH after a single prolonged stress (SPS) treatment in rats. Three weeks later, we evaluated the effects of this pharmacological treatment on anxiety-related behaviors and extinction of contextual fear memory. We also accessed hippocampal autophagy and the expression of 5-HT3A subunit, Beclin-1, LC3-I, and LC3-II in the DH. We found that SPS treatment did not alter anxiety-related behaviors but prolonged the extinction of contextual fear memory, and such a behavioral phenomenon was correlated with increased hippocampal autophagy, decreased 5-HT3A expression, and increased expression of Beclin-1 and LC3-II/LC3-I ratio in the DH. Furthermore, intraDH infusions of SR57227 dose-dependently promoted the extinction of contextual fear memory, prevented hippocampal autophagy, and decreased expression of Beclin-1 and LC3-II/LC3-I ratio in the DH. These results indicated that 5-HT3 receptor in the hippocampus may play a critical role in the pathogenesis of hippocampal autophagy, and is likely involved in the pathophysiology of PTSD.

  2. Electroacupuncture at ST-36 relieves visceral hypersensitivity and decreases 5-HT(3) receptor level in the colon in chronic visceral hypersensitivity rats.

    PubMed

    Chu, Dan; Cheng, Pengfei; Xiong, Huiling; Zhang, Junjun; Liu, Shi; Hou, Xiaohua

    2011-05-01

    Visceral hypersensitivity is an important pathological mechanism of irritable bowel syndrome. Electroacupuncture (EA) could relieve chronic visceral hypersensitivity (CVH) in rats. However, little information is available about the mechanism. The aim of this study was to confirm the effects of EA at acupoint ST-36 (Zusanli) on CVH induced by the chemical colorectal irritation during postnatal development of rats, and to explore the possible 5-HT(3) receptor mechanism. Rats were randomized into four groups, including the normal control group, CVH group, CVH with EA group, and CVH with sham EA group. The abdominal electromyogram (EMG) in response to colorectal distension was selected as the index for measurement of visceral hypersensitivity. 5-HT(3) receptors were analyzed through reverse transcription-polymerase chain reaction and western blot. EA at ST-36 significantly decreased evoked EMG. The expression of 5-HT(3) receptor in the colon was increased in rats with CVH, and decreased after EA treatment. EA at acupoint ST-36 attenuates CVH in rats and decreases 5-HT(3) receptor level in the colon. Decreased 5-HT(3) receptor level in the colon may mediate the beneficial effect of EA in rats with CVH.

  3. 5-HT3A -driven green fluorescent protein delineates gustatory fibers innervating sour-responsive taste cells: A labeled line for sour taste?

    PubMed

    Stratford, J M; Larson, E D; Yang, R; Salcedo, E; Finger, T E

    2017-07-01

    Taste buds contain multiple cell types with each type expressing receptors and transduction components for a subset of taste qualities. The sour sensing cells, Type III cells, release serotonin (5-HT) in response to the presence of sour (acidic) tastants and this released 5-HT activates 5-HT3 receptors on the gustatory nerves. We show here, using 5-HT3A GFP mice, that 5-HT3 -expressing nerve fibers preferentially contact and receive synaptic contact from Type III taste cells. Further, these 5-HT3 -expressing nerve fibers terminate in a restricted central-lateral portion of the nucleus of the solitary tract (nTS)-the same area that shows increased c-Fos expression upon presentation of a sour tastant (30 mM citric acid). This acid stimulation also evokes c-Fos in the laterally adjacent mediodorsal spinal trigeminal nucleus (DMSp5), but this trigeminal activation is not associated with the presence of 5-HT3 -expressing nerve fibers as it is in the nTS. Rather, the neuronal activation in the trigeminal complex likely is attributable to direct depolarization of acid-sensitive trigeminal nerve fibers, for example, polymodal nociceptors, rather than through taste buds. Taken together, these findings suggest that transmission of sour taste information involves communication between Type III taste cells and 5-HT3 -expressing afferent nerve fibers that project to a restricted portion of the nTS consistent with a crude mapping of taste quality information in the primary gustatory nucleus. © 2017 Wiley Periodicals, Inc.

  4. 5-HT3 and 5-HT4 receptor-mediated facilitation of the emptying phase of the peristaltic reflex in the marmoset isolated ileum.

    PubMed Central

    Tuladhar, B. R.; Costall, B.; Naylor, R. J.

    1996-01-01

    .83 +/- 0.36 respectively in the presence of GR 113808 (30 nM). 6. In the presence of a high concentration of (10 microM) 5-methoxytryptamine the subsequent addition of 2-methyl-5-HT (3-10 microM) but not 5-methoxytryptamine (10 microM) facilitated peristalsis; the effect of 3 microM 2-methyl-5-HT was significantly decreased by 2 microM ondansetron. 7. It is concluded that the facilitation of the peristaltic reflex in the marmoset intestine induced by 5-HT at submicromolar concentrations involves a 5-HT4 receptor stimulation with an additional 5-HT3 receptor activation at higher concentrations. PMID:8732276

  5. Effects of various serotonin agonists, antagonists, and uptake inhibitors on the discriminative stimulus effects of methamphetamine in rats.

    PubMed

    Munzar, P; Laufert, M D; Kutkat, S W; Nováková, J; Goldberg, S R

    1999-10-01

    Neurochemical studies indicate that methamphetamine increases central serotonin (5-HT) levels more markedly than other psychomotor stimulants such as amphetamine or cocaine. In the present study, we investigated 5-HT involvement in the discriminative stimulus effects of methamphetamine. In Sprague-Dawley rats trained to discriminate 1.0 mg/kg methamphetamine i.p. from saline under a fixed-ratio schedule of food presentation, the effects of selected 5-HT agonists, antagonists, and uptake inhibitors were tested. Fluoxetine (1.8-18.0 mg/kg) and clomipramine (3.0-18.0 mg/kg), selective serotonin uptake inhibitors, did not produce any methamphetamine-like discriminative stimulus effects when administered alone, but fluoxetine (5.6 mg/kg), unlike clomipramine (5.6 mg/kg), significantly shifted the methamphetamine dose-response curve to the left. Both 8-hydroxy-2-dipropylaminotetralin (0.03-0.56 mg/kg), a full agonist, and buspirone (1.0-10.0 mg/kg), a partial agonist at 5-HT(1A) receptors, partially generalized to the training dose of methamphetamine but only at high doses that decreased response rate. This generalization was antagonized by the coadministration of the 5-HT(1A) antagonist WAY-100635 (1.0 mg/kg). WAY-100635 (1.0 mg/kg) also partially reversed the leftward shift of the methamphetamine dose-response curve produced by fluoxetine. (+/-)-1-(2, 5-Dimethoxy-4-iodophenyl)-2-aminopropane (0.3 mg/kg), a 5-HT(2A/2C) agonist, shifted the methamphetamine dose-response curve to the left, and this leftward shift was antagonized by the coadministration of ketanserin (3.0 mg/kg), a 5-HT(2A/2C) antagonist. Ketanserin (3.0 mg/kg) also produced a shift to the right in the methamphetamine dose-response curve and completely reversed the leftward shift in the methamphetamine dose-response curve produced by fluoxetine. In contrast, tropisetron (1.0 mg/kg), a 5-HT(3) antagonist, produced a shift to the left of the methamphetamine dose-response curve, and this effect of tropisetron

  6. A molecular dynamics approach to receptor mapping: application to the 5HT3 and beta 2-adrenergic receptors.

    PubMed

    Gouldson, P R; Winn, P J; Reynolds, C A

    1995-09-29

    A molecular dynamics-based approach to receptor mapping is proposed, based on the method of Rizzi (Rizzi, J. P.; et al. J. Med. Chem. 1990, 33, 2721). In Rizzi's method, the interaction energy between a series of drug molecules and probe atoms (which mimic functional groups on the receptor, such as hydrogen bond donors) was calculated. These interactions were calculated on a three-dimensional grid within a molecular mechanics parameters, were placed at these minima. The distances between the dummy atom sites were monitored during molecular dynamics simulations and plotted as distance distribution functions. Important distances within the receptor became apparent, as drugs with a common mode of binding share similar peaks in the distance distribution functions. In the case of specific 5HT3 ligands, the important donor--acceptor distance within the receptor has a range of ca. 7.9--8.9 A. In the case of specific beta 2-adrenergic ligands, the important donor--acceptor distances within the receptor lie between ca. 7--9 A and between 8 and 10 A. These distances distribution functions were used to assess three different models of the beta 2-adrenergic G-protein-coupled receptor. The comparison of the distance distribution functions for the simulation with the actual donor--acceptor distances in the receptor models suggested that two of the three receptor models were much more consistent with the receptor-mapping studies. These receptor-mapping studies gave support for the use of rhodopsin, rather than the bacteriorhodopsin template, for modeling G-protein-coupled receptors but also sounded a warning that agreement with binding data from site-directed mutagenesis experiments does not necessarily validate a receptor model.

  7. Modes and nodes explain the mechanism of action of vortioxetine, a multimodal agent (MMA): blocking 5HT3 receptors enhances release of serotonin, norepinephrine, and acetylcholine.

    PubMed

    Stahl, Stephen M

    2015-10-01

    Vortioxetine is an antidepressant with multiple pharmacologic modes of action at targets where serotonin neurons connect with other neurons. 5HT3 receptor antagonism is one of these actions, and this leads to increased release of norepinephrine (NE), acetylcholine (ACh), and serotonin (5HT) within various brain circuits.

  8. Spinal 5-HT3 receptors mediate descending facilitation and contribute to behavioral hypersensitivity via a reciprocal neuron-glial signaling cascade

    PubMed Central

    2014-01-01

    Background It has been recently recognized that the descending serotonin (5-HT) system from the rostral ventromedial medulla (RVM) in the brainstem and the 5-HT3 receptor subtype in the spinal dorsal horn are involved in enhanced descending pain facilitation after tissue and nerve injury. However, the mechanisms underlying the activation of the 5-HT3 receptor and its contribution to facilitation of pain remain unclear. Results In the present study, activation of spinal 5-HT3 receptors by intrathecal injection of a selective 5-HT3 receptor agonist SR 57227 induced spinal glial hyperactivity, neuronal hyperexcitability and pain hypersensitivity in rats. We found that there was neuron-to-microglia signaling via the chemokine fractalkine, microglia to astrocyte signaling via cytokine IL-18, astrocyte to neuronal signaling by IL-1β, and enhanced activation of NMDA receptors in the spinal dorsal horn. Glial hyperactivation in spinal dorsal horn after hindpaw inflammation was also attenuated by molecular depletion of the descending 5-HT system by intra-RVM Tph-2 shRNA interference. Conclusions These findings offer new insights into the cellular and molecular mechanisms at the spinal level responsible for descending 5-HT-mediated pain facilitation during the development of persistent pain after tissue and nerve injury. New pain therapies should focus on prime targets of descending facilitation-induced glial involvement, and in particular the blocking of intercellular signaling transduction between neurons and glia. PMID:24913307

  9. Dual role of serotonin in the acquisition and extinction of reward-driven learning: involvement of 5-HT1A, 5-HT2A and 5-HT3 receptors.

    PubMed

    Frick, Luciana Romina; Bernardez-Vidal, Micaela; Hocht, Christian; Zanutto, Bonifacio Silvano; Rapanelli, Maximiliano

    2015-01-15

    Serotonin (5-HT) has been proposed as a possible encoder of reward. Nevertheless, the role of this neurotransmitter in reward-based tasks is not well understood. Given that the major serotonergic circuit in the rat brain comprises the dorsal raphe nuclei and the medial prefrontal cortex (mPFC), and because the latter structure is involved in the control of complex behaviors and expresses 1A (5-HT1A), 2A (5-HT2A), and 3 (5-HT3) receptors, the aim was to study the role of 5-HT and of these receptors in the acquisition and extinction of a reward-dependent operant conditioning task. Long Evans rats were trained in an operant conditioning task while receiving fluoxetine (serotonin reuptake inhibitor, 10mg/kg), tianeptine (serotonin reuptake enhancer, 10mg/kg), buspirone (5-HT1A partial agonist, 10mg/kg), risperidone (5-HT2A antagonist, 1mg/kg), ondansetron (5-HT3 antagonist, 2mg/kg) or vehicle. Then, animals that acquired the operant conditioning without any treatment were trained to extinct the task in the presence of the pharmacological agents. Fluoxetine impaired acquisition but improved extinction. Tianeptine administration induced the opposite effects. Buspirone induced a mild deficit in acquisition and had no effects during the extinction phase. Risperidone administration resulted in learning deficits during the acquisition phase, although it promoted improved extinction. Ondansetron treatment showed a deleterious effect in the acquisition phase and an overall improvement in the extinction phase. These data showed a differential role of 5-HT in the acquisition and extinction of an operant conditioning task, suggesting that it may have a dual function in reward encoding.

  10. Cation-pi interactions in ligand recognition by serotonergic (5-HT3A) and nicotinic acetylcholine receptors: the anomalous binding properties of nicotine.

    PubMed

    Beene, Darren L; Brandt, Gabriel S; Zhong, Wenge; Zacharias, Niki M; Lester, Henry A; Dougherty, Dennis A

    2002-08-13

    A series of tryptophan analogues has been introduced into the binding site regions of two ion channels, the ligand-gated nicotinic acetylcholine and serotonin 5-HT(3A) receptors, using unnatural amino acid mutagenesis and heterologous expression in Xenopus oocytes. A cation-pi interaction between serotonin and Trp183 of the serotonin channel 5-HT(3A)R is identified for the first time, precisely locating the ligand-binding site of this receptor. The energetic contribution of the observed cation-pi interaction between a tryptophan and the primary ammonium ion of serotonin is estimated to be approximately 4 kcal/mol, while the comparable interaction with the quaternary ammonium of acetylcholine is approximately 2 kcal/mol. The binding mode of nicotine to the nicotinic receptor of mouse muscle is examined by the same technique and found to differ significantly from that of the natural agonist, acetylcholine.

  11. Regulation of the 5-HT3A receptor-mediated current by alkyl 4-hydroxybenzoates isolated from the seeds of Nelumbo nucifera.

    PubMed

    Youn, Ui Joung; Lee, Jun-Ho; Lee, Yoo Jin; Nam, Joo Won; Bae, Hyunsu; Seo, Eun-Kyoung

    2010-09-01

    Four known alkyl 4-hydroxybenzoates, i.e., methyl 4-hydroxybenzoate (1), ethyl 4-hydroxybenzoate (2), propyl 4-hydroxybenzoate (3), and butyl 4-hydroxybenzoate (4), were isolated from the seeds of Nelumbo nucifera Gaertner (Nymphaeaceae) for the first time. The structures of the isolates were identified by 1D- and 2D-NMR spectroscopy and comparison with published values. The compounds were evaluated for their effects on the 5-HT-stimulated inward current (I(5-HT)) mediated by the human 5-HT(3)A receptors expressed in Xenopus oocytes. Compounds 1 and 2 enhanced the I(5-HT), but 4 reduced it. These results indicate that 4 is an inhibitor of the 5-HT(3)A receptors expressed in Xenopus oocytes.

  12. Alcohols potentiate the function of 5-HT3 receptor–channels on NCB-20 neuroblastoma cells by favouring and stabilizing the open channel state

    PubMed Central

    Zhou, Qing; Verdoorn, Todd A; Lovinger, David M

    1998-01-01

    5-HT3 receptor-mediated ion current was recorded from NCB-20 neuroblastoma cells using the whole-cell patch-clamp technique. Rapid drug superfusion was used to study the mechanism of alcohol potentiation of 5-HT3 receptor function and to analyse effects of alcohols on receptor-channel kinetics in detail.Trichloroethanol (TCEt) increased in a dose-dependent way the initial slope, 20–80 % rise time and measured desensitization rate of the current induced by low concentrations (1–2 μm) of 5-HT. Ethanol (EtOH) and butanol (ButOH) had similar effects on the 5-HT3 receptor-induced current.TCEt and ButOH decreased the measured desensitization rate of current induced by 10 μm 5-HT, a maximally effective concentration of agonist. These alcohols also increased the relative amplitude of steady state to peak current induced by 2 or 10 μm 5-HT, indicating a possible decrease in the intrinsic rate of desensitization.TCEt also decreased the deactivation rate of the current activated by 2 μm 5-HT after a short pulse of agonist application.Current sweeps generated by 1 μm 5-HT in the presence or absence of 10 mm TCEt or 100 mm EtOH were well fitted using a modified standard kinetic model derived from the nicotinic acetylcholine receptor. This analysis indicated that potentiation by alcohols could be accounted for by increases in the association rate constant coupled with decreases in the dissociation and desensitization rate constants.This study suggests that alcohols potentiate 5-HT3 receptor-mediated current by both increasing the rate of channel activation and stabilizing the open state by decreasing the rates of channel deactivation and desensitization. PMID:9518697

  13. Fluvoxamine alleviates seizure activity and downregulates hippocampal GAP-43 expression in pentylenetetrazole-kindled mice: role of 5-HT3 receptors.

    PubMed

    Alhaj, Momen W; Zaitone, Sawsan A; Moustafa, Yasser M

    2015-06-01

    Epilepsy has been documented to lead to many changes in the nervous system including cell loss and mossy fiber sprouting. Neuronal loss and aberrant neuroplastic changes in the dentate gyrus of the hippocampus have been identified in the pentylenetetrazole (PTZ) kindling model. Antiseizure activity of selective serotonin reuptake inhibitors has been reported in several studies. In the current study, the protective effect of fluvoxamine against PTZ-kindling was investigated in terms of seizure scores, neuronal loss, and regulation of hippocampal neuroplasticity. Further, the role of 5-HT3 receptors was determined. Kindling was induced by repeated injections of PTZ (35 mg/kg) thrice weekly, for a total of 13 injections. One hundred male albino mice were allocated into 10 groups: (1) saline, (2) PTZ, (3) diazepam (1 mg/kg)+PTZ, (4-6) fluvoxamine (5, 10 or 20 mg/kg)+PTZ, (7) ondansetron+fluvoxamine (20 mg/kg)+PTZ, (8) ondansetron+PTZ group, (9) ondansetron (2 mg/kg, i.p.)+saline, and (10) fluvoxamine (20 mg/kg)+saline. PTZ-kindled mice showed high seizure activity, hippocampal neuronal loss, and expression of growth-associated phosphoprotein (GAP-43) compared with saline-treated mice. Repeated administration of fluvoxamine (20 mg/kg) in PTZ-kindled mice suppressed seizure scores, protected against hippocampal neuronal loss, and downregulated GAP-43 expression, without producing any signs of the 5-HT syndrome in healthy rats. Importantly, pretreatment with a selective 5-HT3 receptor blocker (ondansetron) attenuated the aforementioned effects of fluvoxamine. In conclusion, the ameliorating effect of fluvoxamine on hippocampal neurons and neuroplasticity in PTZ-kindled mice was, at least in part, dependent on enhancement of hippocampal serotoninergic transmission at 5-HT3 receptors.

  14. Involvement of nitric oxide in 5-HT(3) receptor agonist-induced fluid accumulation in jejunum and colon of anesthetized rats.

    PubMed

    Veeresh, B; Patil, Basanagouda M; Veeresh Babu, S V; Jeedi, Neelakanth M; Unger, Banappa S

    2009-10-01

    The aim of the present study was to investigate the involvement of nitric oxide in 5-HT(3) receptor agonist-induced fluid accumulation in jejunum and colon of anesthetized rats. Fluid movement in jejunum and colon were determined simultaneously in the same rat, by modifying the Beubler method. Nomega-nitro-L-arginine (L-NNA, 20 mg/kg, s.c) alone and in combination with L-arginine (L-Arg, 150 mg/kg s.c) or D-arginine (D-Arg, 150 mg/kg, s.c) were administered 30 min before administration of 1-PBG (18.5 mug/kg, i.v). Intravenous administration of 1-phenylbiguanide (1-PBG) induced a net secretion of fluid in both jejunum and colon. 1-PBG had a more prominent secretory effect in the colon, causing a three-fold increase in volume of fluid secreted/g of colon than in the jejunum. Pretreatment with (L-NNA) prevented the 1-PBG-induced fluid accumulation in both jejunum and colon. The inhibitory effect of L-NNA on 1-PBG-induced fluid accumulation was reversed by L-Arg but not by D-Arg. These results provide evidence that nitric oxide plays an important role in 5-HT(3) receptor agonist-induced fluid accumulation in jejunum and colon of anesthetized rats.

  15. Involvement of nitric oxide in 5-HT3 receptor agonist-induced fluid accumulation in jejunum and colon of anesthetized rats

    PubMed Central

    Veeresh, B.; Patil, Basanagouda M.; Veeresh Babu, S.V.; Jeedi, Neelakanth M.; Unger, Banappa S.

    2009-01-01

    Objectives: The aim of the present study was to investigate the involvement of nitric oxide in 5-HT3 receptor agonist-induced fluid accumulation in jejunum and colon of anesthetized rats. Materials and Methods: Fluid movement in jejunum and colon were determined simultaneously in the same rat, by modifying the Beubler method. Nω-nitro-L-arginine (L-NNA, 20 mg/kg, s.c) alone and in combination with L-arginine (L-Arg, 150 mg/kg s.c) or D-arginine (D-Arg, 150 mg/kg, s.c) were administered 30 min before administration of 1-PBG (18.5 μg/kg, i.v). Results: Intravenous administration of 1-phenylbiguanide (1-PBG) induced a net secretion of fluid in both jejunum and colon. 1-PBG had a more prominent secretory effect in the colon, causing a three-fold increase in volume of fluid secreted/g of colon than in the jejunum. Pretreatment with (L-NNA) prevented the 1-PBG-induced fluid accumulation in both jejunum and colon. The inhibitory effect of L-NNA on 1-PBG-induced fluid accumulation was reversed by L-Arg but not by D-Arg. Conclusion: These results provide evidence that nitric oxide plays an important role in 5-HT3 receptor agonist-induced fluid accumulation in jejunum and colon of anesthetized rats. PMID:20177493

  16. Effect of palonosetron (5HT-3 antagonist) and pantoprazole (proton pump inhibitor) against surgical esophagitis induced by forestomach and pylorus ligation in albino rats.

    PubMed

    Kumar, A; Gautam, S; Rawat, J K; Singh, M; Saraf, S A; Kaithwas, G

    2016-01-01

    This study was embarked upon to evaluate the effects of pantoprazole and palonosetron on experimental esophagitis in albino wistar rats. Groups of rats, fasted for 36 h, were subjected to pylorus and forestomach ligation, supervened by treatment with normal saline (3 ml/kg, po, sham control), esophagitis control (3 ml/kg, po), pantoprazole (30 mg/kg, po), palonosetron (0.5 mg/kg, po), and their combination. Animals were sacrificed after 12 h and appraised for the volume of gastric juices, total acidity, free acidity, and esophagitis index. Esophageal tissues were further figured out biochemically for markers of oxidative stress and inflammatory mediators. The combination therapy comparably inhibited the esophagitis index (52.86%), gastric volume (66.04%), free acidity (43.76%), and total acidity (42.60%) in comparison with toxic control. The combination therapy also subsidized the biochemical and inflammatory markers to the purview less than toxic control. The morphological changes were scrutinized by scanning electron microscopy and were observed to demonstrate momentous protection by the amalgamation therapy. Combination therapy with pantoprazole and palonosetron flaunted sententious protection against experimental esophagitis.

  17. Anti-depressant like activity of N-n-butyl-3-methoxyquinoxaline-2-carboxamide (6o) a 5-HT3 receptor antagonist.

    PubMed

    Bhatt, Shvetank; Mahesh, Radhakrishnan; Devadoss, Thangaraj; Jindal, Ankur

    2013-06-01

    The compound 6o (at 0.5, 1 and 2 mg/kg, ip) with optimum log P and pA2 value, was subjected to forced swim test (FST) and tail suspension test (TST). The compound 6o significantly reduced the duration of immobility in mice without affecting the base line locomotion in actophotometer. Moreover, 6o (2 mg/kg, ip), potentiated the 5-hydroxytryptophan (5-HTP)-induced head twitch responses in mice and at 1 and 2 mg/kg, ip antagonized the reserpine-induced hypothermia (RIH) in rats. In interaction studies with various standard drugs/ligands using FST, 6o (1 and 2 mg/kg, ip) potentiated the anti-depressant effect fluoxetine (5 mg/kg, ip) and reversed the depressant effect of parthenolide (1 mg/kg, ip) by reducing the duration of immobility. Furthermore, 6o (1 and 2 mg/kg, ip) potentiated the effect of bupropion (10 mg/kg, ip) in TST. The behavioural anomalies of the olfactory bulbectomised (OBX) rats were augmented by chronic 6o (1 and 2 mg/kg) treatment as observed from the modified open field test (parameters: ambulation, rearing, fecal pellet). The results suggest that compound 6o exhibited anti-depressant like effect in rodent models of depression.

  18. Bidirectional amygdaloid control of neuropathic hypersensitivity mediated by descending serotonergic pathways acting on spinal 5-HT3 and 5-HT1A receptors.

    PubMed

    Sagalajev, B; Bourbia, N; Beloushko, E; Wei, H; Pertovaara, A

    2015-04-01

    Amygdala is involved in processing of primary emotions and particularly its central nucleus (CeA) also in pain control. Here we studied mechanisms mediating the descending control of mechanical hypersensitivity by the CeA in rats with a peripheral neuropathy in the left hind limb. For drug administrations, the animals had a guide cannula in the right CeA and an intrathecal catheter or another guide cannula in the medullary raphe. Hypersensitivity was tested with monofilaments. Glutamate administration in the CeA produced a bidirectional effect on hypersensitivity that varied from an increase at a low-dose (9μg) to a reduction at high doses (30-100μg). The increase but not the reduction of hypersensitivity was prevented by blocking the amygdaloid NMDA receptor with a dose of MK-801 that alone had no effects. The glutamate-induced increase in hypersensitivity was reversed by blocking the spinal 5-HT3 receptor with ondansetron, whereas the reduction in hypersensitivity was reversed by blocking the spinal 5-HT1A receptor with WAY-100635. Both the increase and decrease of hypersensitivity induced by amygdaloid glutamate treatment were reversed by medullary administration of a 5-HT1A agonist, 8-OH-DPAT, that presumably produced autoinhibition of serotonergic cell bodies in the medullary raphe. The results indicate that depending on the dose, glutamate in the CeA has a descending facilitatory or inhibitory effect on neuropathic pain hypersensitivity. Serotoninergic raphe neurons are involved in mediating both of these effects. Spinally, the 5-HT3 receptor contributes to the increase and the 5-HT1A receptor to the decrease of neuropathic hypersensitivity induced by amygdaloid glutamate.

  19. Effect of quipazine, a selective 5-HT3 agonist, on dietary self-selection of different macronutrient diets in male and female rats.

    PubMed

    Mok, E; Paquette, M; Thibault, L

    2000-06-01

    Macronutrient intakes, 2h and 12h, following administration of a selective 5-HT3 agonist, quipazine, N methyl, dimaleate (QUIPAZINE; 2.5, 5.0 and 7.5 mg/kg, i.p.) at dark onset were examined in three groups of adult male and female Wistar rats fed different sources of the three macronutrients: Group 1 (casein, corn starch, safflower oil), Group 2 (egg protein, corn starch/sucrose, lard) and Group S (casein hydrolysate, maltose dextrin, butter). QUIPAZINE decreased total food intake only in female rats from Group 1 (2 h) at a dose of 7.5 mg/kg and Group 2 (2h and 12h) with doses of 2.5 and 7.5 mg/kg. Intakes from corn starch and corn starch/sucrose diet (12h) were reduced in male and female rats, respectively, with doses of 2.5 and 7.5 mg/kg of QUIPAZINE. In conclusion, when provided with different sources of the three macronutrients, quipazine injection reduces specifically carbohydrate ingestion from corn starch-containing diets in male and female rats. Thus, the nature of the macronutrient source is of major importance to assess the effect of a drug on nutrient-specific selection.

  20. Stimulation of 5-HT1A, 5-HT1B, 5-HT2A/2C, 5-HT3 and 5-HT4 receptors or 5-HT uptake inhibition: short- and long-term memory.

    PubMed

    Meneses, Alfredo

    2007-11-22

    In order to determine whether short- (STM) and long-term memory (LTM) function in serial or parallel manner, serotonin (5-hydroxtryptamine, 5-HT) receptor agonists were tested in autoshaping task. Results show that control-vehicle animals were modestly but significantly mastering the autoshaping task as illustrated by memory scores between STM and LTM. Thus, post-training administration of 8-OHDPAT (agonist for 5-HT(1A/7) receptors) only at 0.250 and 0.500 mg/kg impaired both STM and LTM. CGS12066 (agonist for 5-HT(1B)) produced biphasic affects, at 5.0 mg/kg impaired STM but at 1.0 and 10.0 mg/kg, respectively, improved or impaired LTM. DOI (agonist for 5-HT(2A/2C) receptors) dose-dependently impaired STM and, at 10.0 mg/kg only impaired LTM. Both, STM and LTM were impaired by either mCPP (mainly agonist for 5-HT(2C) receptors) or mesulergine (mainly antagonist for 5-HT(2C) receptors) lower dose. The 5-HT(3) agonist mCPBG at 1.0 impaired STM and its higher dose impaired both STM and LTM. RS67333 (partial agonist for 5-HT(4) receptors), at 5.0 and 10.0 mg/kg facilitated both STM and LTM. The higher dose of fluoxetine (a 5-HT uptake inhibitor) improved both STM and LTM. Using as head-pokes during CS as an indirect measure of food-intake showed that of 30 memory changes, 21 of these were unrelated to the former. While some STM or LTM impairments can be attributed to decrements in food-intake, but not memory changes (either increase or decreases) produced by 8-OHDPAT, CGS12066, RS67333 or fluoxetine. Except for animals treated with DOI, mCPBG or fluoxetine, other groups treated with 5-HT agonists 6 h following autoshaping training showed similar LTM and unmodified CS-head-pokes scores.

  1. Importance of M2-M3 loop in governing properties of genistein at the α7 nicotinic acetylcholine receptor inferred from α7/5-HT3A chimera.

    PubMed

    Grønlien, Jens Halvard; Ween, Hilde; Thorin-Hagene, Kirsten; Cassar, Steven; Li, Jinhe; Briggs, Clark A; Gopalakrishnan, Murali; Malysz, John

    2010-11-25

    Genistein and 5-hydroxyindole (5-HI) potentiate the α7 nicotinic acetylcholine receptor current by primarily increasing peak amplitude, a property of type I α7 positive allosteric modulation. In this study, the effects of these two compounds were investigated at two different α7/5-HT(3) chimeras (chimera 1, comprising of extracellular α7 N-terminus fused to the remainder of 5-HT(3A), and chimera 2 containing an additional α7 encoded M2-M3 loop), and wild-type α7 and 5-HT(3A) receptors. Agonist-evoked responses, examined by expression of the chimeras in Xenopus laevis oocytes or HEK-293 cells, revealed that currents decayed slower and compounds {rank order: N-[(3R)-1-azabicyclo[2.2.2]oct-3-yl]-4-chlorobenzamide hydrochloride (PNU-282987)~2-(1,4-diazabicyclo[3.2.2]nonan-4-yl)-5-phenyl-1,3,4-oxadiazole (NS6784)>acetylcholine>choline} were more potent in chimera 2 than chimera 1 or α7 receptors. In chimera 2, genistein and 5-HI potentiated agonist-evoked responses (EC(50): 4-5 μM for genistein and 300-500 μM for 5-HI) and at higher concentrations evoked current directly consistent with ago-allosteric modulation. At chimera 1 and 5-HT(3A) receptors, neither compound directly evoked any current and 5-HI, only at chimera 1, was able to potentiate agonist-evoked responses. Genistein and 5-HI did not inhibit the binding of the α7 agonist [(3)H](1S,4S)-2,2-dimethyl-5-(6-phenylpyridazin-3-yl)-5-aza-2-azoniabicyclo[2.2.1] heptane ([(3)H]A-585539) to rat brain or chimera 2. In summary, this study supports the role of the M2-M3 loop being critical for the positive allosteric effect of genistein, but not 5-HI, and in agonist-evoked response fine-tuning. The identification of distinct α7 receptor modulatory sites offers unique opportunities for developing CNS therapeutics and understanding its pharmacology.

  2. On-line focusing of 5-hydroxy-tryptamine type 3 receptor antagonists via the combination of field-enhanced sample injection and dynamic pH junction in capillary electrophoresis with amperometric detection.

    PubMed

    Li, Libo; Xu, Lei; Huang, Jianshe; You, Tianyan

    2014-02-28

    In the present work, an on-line dual focusing technique based on field-enhance sample injection (FASI) and dynamic pH junction (DypH) was developed for the analysis of two 5-hydroxy-tryptamine type 3 receptor (5-HT3) antagonists ondansetron (Ond) and tropisetron (Tro) by capillary electrophoresis with amperometric detection (CE-AD) system. By preparing the sample in a lower conductivity (FASI condition) and lower pH value (DypH condition) matrix relative to the background electrolyte (BGE) solution, a simple and effective dual focusing approach, FASI-DypH was achieved. In this stacking mode, a large amount of analytes could be electrokinetically injected into the capillary and stacked at the boundary of the sample and the BGE zone as a result of deprotonation and decrease in the electric field. Effects of separation, detection and FASI-DypH focusing conditions were investigated in detail. Under the optimum conditions, good separation for Ond and Tro was achieved within 8min. In comparison with the conventional CE-AD analysis method, the present dual focusing technique enabled the enhancement factors in terms of peak heights to reach 357-fold and 345-fold for Ond and Tro, respectively. The limits of detection (LODs) (S/N=3) for Ond and Tro were 2nM and 5nM, respectively. The intraday and interday repeatabilities (RSDs) were less than 4.5% and 2.9% for peak height and migration time, respectively. The proposed method was successfully applied for the analysis of Ond and Tro in human urine sample. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Efficacy and safety of 5-hydroxytryptamine 3 receptor antagonists in irritable bowel syndrome: A systematic review and meta-analysis of randomized controlled trials

    PubMed Central

    Tang, Yurong; Xiong, Wenjie; Shen, Xiaoxue; Jiang, Ling; Lin, Lin

    2017-01-01

    Aim We assessed the efficacy and safety of 5-hydroxytryptamine (5-HT3) receptor antagonists in adults with non-constipated irritable bowel syndrome (IBS) or diarrhea-predominant IBS (IBS-D). Methods We searched PubMed, MEDLINE, EMBASE, and the Cochrane Controlled Trials Register for randomized controlled trials (RCTs) involving adults with non-constipated IBS or IBS-D that compared 5-HT3 receptor antagonists with placebo or other conventional treatment. Dichotomous symptom data were pooled to obtain the relative risk (RR) and 95% confidence intervals (CIs) for improving global IBS symptoms, abdominal pain and abnormal bowel habits, or stool consistency symptoms after therapy, and adverse events, including constipation. Meta- analysis was performed with Mantel Haenszel method using Revman 5.3 software. Results We included 21 RCTs; 16 were high quality (Jadad score ≥ 4). The pooled RR of global IBS symptoms improved by 5-HT3 receptor antagonists versus placebo or mebeverine was 1.56 (95% CI: 1.43–1.71); alosetron, ramosetron, and cilansetron had similar treatment effects. The pooled RR of abdominal pain relieved by 5-HT3 receptor antagonists versus placebo was 1.33 (95% CI: 1.26–1.39). The pooled RR showed that 5-HT3 receptor antagonists improved abnormal bowel habits or stool consistency symptoms (RR = 1.63, 95% CI: 1.33, 1.99). The pooled RR of adverse events following 5-HT3 receptor antagonist treatment was 1.15 (95% CI: 1.08, 1.22). Subgroup analysis indicated that alosetron had a high rate of adverse effects (RR = 1.16, 95% CI: 1.08, 1.25); adverse events following ramosetron treatment were not statistically significantly different. 5-HT3 receptor antagonists were likelier to cause constipation: the pooled RR of constipation developing with 5-HT3 receptor antagonist versus placebo was 3.71 (95% CI: 2.98–4.61). However, constipation was likelier in patients with non-constipated IBS after taking 5-HT3 receptor antagonists than in patients with IBS-D only

  4. Efficacy of palonosetron (PAL) compared to other serotonin inhibitors (5-HT3R) in preventing chemotherapy-induced nausea and vomiting (CINV) in patients receiving moderately or highly emetogenic (MoHE) treatment: systematic review and meta-analysis.

    PubMed

    Botrel, Tobias Engel Ayer; Clark, Otávio Augusto C; Clark, Luciana; Paladini, Luciano; Faleiros, Enéas; Pegoretti, Bruna

    2011-06-01

    The objective of this work is to perform a systematic review and meta-analysis of all randomized controlled trials comparing a single intravenous dose of palonosetron (PAL) 0.25 mg with other 5-HT(3)R in patients receiving moderately or highly emetogenic (MoHE) chemotherapy. Several databases were searched, including MEDLINE, EMBASE, LILACS, and CENTRAL. The primary endpoints were the incidence of acute and delayed nausea and vomiting. The side effects of each treatment were analyzed. A subgroup analysis was performed to evaluate the influence of the use of corticosteroids. The results are expressed as risk ratio (RR) and the correspondent 95% confidence interval (CI). Five studies were included, with 2057 patients. PAL was compared with ondansetron, granisetron, and dolasetron. Patients in PAL group had less nausea, both acute (RR = 0.86; CI 95% = 0.76 to 0.96; p = 0.007) and delayed (RR = 0.82; CI95% = 0.75 to 0.89; p < 0.00001). They also had less acute vomiting (RR = 0.76; CI 95% = 0.66 to 0.88; p = 0.0002) and delayed vomiting (RR = 0.76; CI95% = 0.68 to 0.85; p < 0.00001). There were no statistical differences in side effects like headache (RR = 0.84; CI 95% = 0.61 to 1.17; p = 0.30), dizziness (RR = 0.40; CI 95% = 0.13 to 1.27; p = 0.12), constipation (RR = 1.29; CI 95% = 0.77 to 2.17; p = 0.33) or diarrhea (RR = 0.67; CI 95% = 0.24 to 1.85; p = 0.44). Patients receiving PAL presented less nausea and vomiting regardless of the use of corticoids. We found no statistical heterogeneity in the global analysis. PAL was more effective than the other 5-HT(3)R in preventing acute and delayed CINV in patients receiving MoHE treatments, regardless of the use of concomitant corticosteroids.

  5. Palonosetron for the prevention of chemotherapy-induced nausea and vomiting.

    PubMed

    Mori-Vogt, Sherry; Blazer, Marlo

    2013-08-01

    Chemotherapy-induced nausea and vomiting (CINV) remains both a feared side effect of cancer treatment and a focus of many supportive care initiatives/guidelines. The class of medications known as serotonin receptor antagonists (5-HT3RAs) are integral in the prevention of CINV from both moderately and highly emetogenic chemotherapy. Palonosetron (ALOXI(®)), a second-generation 5-HT3RA, has a higher affinity for the 5-HT3 receptor, has a longer half-life and has unique interactions with the 5-HT3 receptor compared with the current first-generation 5-HT3RA such as ondansetron, granisetron, dolasetron and tropisetron. This may allow palonosetron an advantage in control of CINV. This review article examines the available evidence, the pharmacokinetics and the safety and tolerability of palonosetron in the prevention of CINV.

  6. [Tropisetron for the prevention of nausea and vomiting during chemotherapy: multicenter clinical study].

    PubMed

    Gutiérrez, J; Bronfman, L; Cao, C; Vásquez, A; Derio, L; Rosas, J; del Castillo, C; Yáñez, M; Fodor, M; Gallardo, J; Cerda, B; Torres, R; Orlandi, L; Orlandi, F; Kleinman, S; Vogel, C

    1996-08-01

    The antiemetic effect of tropisetron was studied in 97 cancer patients (67 men, 30 women) receiving cisplatin in doses of 75 mg/m2 or higher. On 279 chemotherapy cycles studied (max 6 per patient) 5 mg of tropisetron was administered once a day i.v on day 1 and p.o. on days 2 to 6. Efficacy preventing vomiting and nausea was measured in 24 hour period as: complete control O episodes, major control 1 to 2 episodes, minor control 3 to 4 episodes and no control 5 or more episodes. Satisfactory vomiting control (complete and major) was 69%, 63%, 82%, 88%, 96% and 96% in days 1 to 6 of cycle 1. Satisfactory nausea control (complete and major) for the same days was 70%, 66%, 72%, 85%, 92% and 97%. Similar data was obtained for the subsequent cycles. Complete vomiting control was obtained in 47%, 35%, 56%, 72%, 81% and 84% and for nausea in 42%, 39%, 48%, 64%, 81% and 87%. 19 patients presented adverse effects (19.6%). Only 2 headache episodes had a definite relation with the antiemetic drug. 12 patients discontinued the medication; 6 due to drug inefficacy, 2 to illness unrelated to the drug, 1 to lack of collaboration, and 3 due to other reasons. We conclude that tropisetron allows satisfactory control of acute and delayed vomiting in a high percentage of patients treated with high doses of cisplatin. The drug does not have significant secondary effects. Tropisetron administration in only one daily dose implies an evident advantage and a treatment cost reduction.

  7. Stability of butorphanol-tropisetron mixtures in 0.9% sodium chloride injection for patient-controlled analgesia use.

    PubMed

    Chen, Fu-Chao; Shi, Xiao-Ya; Li, Peng; Yang, Jin-Guo; Zhou, Ben-Hong

    2015-02-01

    Tropisetron is an adjuvant for butorphanol used in intravenous patient-controlled analgesia (PCA) and has been reported to provide superior pain control. It is efficacious in reducing the incidence of postoperative nausea and vomiting. However, this admixture is not available commercially and stability data applicable to hospital practice are limited. This study aimed to describe the drug compounding and evaluates the long-term (up to 14 days) stability of butorphanol and tropisetron in 0.9% sodium chloride injection for PCA use.In this study, commercial solutions of butorphanol tartrate and tropisetron hydrochloride were combined and further diluted with 0.9% sodium chloride injection to final concentrations of butorphanol tartrate 0.08 mg/mL and tropisetron hydrochloride 0.05 mg/mL. The polyolefin bags and glass bottles were stored at 4°C and 25°C for up to 14 days. The drug stabilities were determined by visual inspection, pH measurement, and high-pressure liquid chromatography assay of drug concentrations.The data obtained for admixtures prepared and stored at temperatures of 25°C and 4°C show the drugs have maintained at least 98% of the initial concentration. All solutions remained clear and colorless over the 14-day period, and the pH value did not change significantly.The results indicate that admixtures of butorphanol tartrate 0.08 mg/mL and tropisetron hydrochloride 0.05 mg/mL in 0.9% sodium chloride injection solution were stable for 14 days when stored in polyolefin bags or glass bottles at 4°C and 25°C and protected from light. The infusion is feasible for manufacturing in pharmacy aseptic units and can be stored for up to 14 days for routine use in PCA infusions.

  8. Stability of Butorphanol–Tropisetron Mixtures in 0.9% Sodium Chloride Injection for Patient-Controlled Analgesia Use

    PubMed Central

    Chen, Fu-Chao; Shi, Xiao-Ya; Li, Peng; Yang, Jin-Guo; Zhou, Ben-Hong

    2015-01-01

    Tropisetron is an adjuvant for butorphanol used in intravenous patient-controlled analgesia (PCA) and has been reported to provide superior pain control. It is efficacious in reducing the incidence of postoperative nausea and vomiting. However, this admixture is not available commercially and stability data applicable to hospital practice are limited. This study aimed to describe the drug compounding and evaluates the long-term (up to 14 days) stability of butorphanol and tropisetron in 0.9% sodium chloride injection for PCA use. In this study, commercial solutions of butorphanol tartrate and tropisetron hydrochloride were combined and further diluted with 0.9% sodium chloride injection to final concentrations of butorphanol tartrate 0.08 mg/mL and tropisetron hydrochloride 0.05 mg/mL. The polyolefin bags and glass bottles were stored at 4°C and 25°C for up to 14 days. The drug stabilities were determined by visual inspection, pH measurement, and high-pressure liquid chromatography assay of drug concentrations. The data obtained for admixtures prepared and stored at temperatures of 25°C and 4°C show the drugs have maintained at least 98% of the initial concentration. All solutions remained clear and colorless over the 14-day period, and the pH value did not change significantly. The results indicate that admixtures of butorphanol tartrate 0.08 mg/mL and tropisetron hydrochloride 0.05 mg/mL in 0.9% sodium chloride injection solution were stable for 14 days when stored in polyolefin bags or glass bottles at 4°C and 25°C and protected from light. The infusion is feasible for manufacturing in pharmacy aseptic units and can be stored for up to 14 days for routine use in PCA infusions. PMID:25674732

  9. Tropisetron Protects Against Acetaminophen-Induced Liver Injury via Suppressing Hepatic Oxidative Stress and Modulating the Activation of JNK/ERK MAPK Pathways

    PubMed Central

    Lee, Hung-Chen; Liao, Chia-Chih; Li, Allen H.

    2016-01-01

    Objectives. To investigate the protective effects of tropisetron on acetaminophen- (APAP-) induced liver injury in a mice model. Methods. C57BL/6 male mice were given tropisetron (0.3 to 10 mg/kg) 30 minutes before a hepatotoxic dose of acetaminophen (300 mg/kg) intraperitoneally. Twenty hours after APAP intoxication, sera alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, hepatic myeloperoxidase (MPO), malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) activities, and liver histopathological changes were examined. The MAP kinases were also detected by western blotting. Results. Our results showed that tropisetron pretreatment significantly attenuated the acute elevations of the liver enzyme ALT level, hepatic MPO activity, and hepatocytes necrosis in a dose-dependent manner (0.3–10 mg/kg) in APAP-induced hepatotoxicity mice. Tropisetron (1 and 3 mg/kg) suppressed APAP-induced hepatic lipid peroxidation expression and alleviated GSH and SOD depletion. Administration of tropisetron also attenuated the phosphorylation of c-Jun-NH2-terminal protein kinase (JNK) and extracellular signal-regulated kinase (ERK) caused by APAP. Conclusion. Our data demonstrated that tropisetron's hepatoprotective effect was in part correlated with the antioxidant, which were mediated via JNK and ERK pathways on acetaminophen-induced liver injury in mice. PMID:27891510

  10. Prophylaxis of Radiation-Induced Nausea and Vomiting Using 5-Hydroxytryptamine-3 Serotonin Receptor Antagonists: A Systematic Review of Randomized Trials

    SciTech Connect

    Salvo, Nadia; Doble, Brett; Khan, Luluel; Amirthevasar, Gayathri; Dennis, Kristopher; Pasetka, Mark; DeAngelis, Carlo; Tsao, May; Chow, Edward

    2012-01-01

    Purpose: To systematically review the effectiveness and safety of 5-hydroxytryptamine-3 receptor antagonists (5-HT3 RAs) compared with other antiemetic medication or placebo for prophylaxis of radiation-induced nausea and vomiting. Methods and Materials: We searched the following electronic databases: MEDLINE, Embase, the Cochrane Central Register of Controlled Clinical Trials, and Web of Science. We also hand-searched reference lists of included studies. Randomized, controlled trials that compared a 5-HT3 RA with another antiemetic medication or placebo for preventing radiation-induced nausea and vomiting were included. We excluded studies recruiting patients receiving concomitant chemotherapy. When appropriate, meta-analysis was conducted using Review Manager (v5) software. Relative risks were calculated using inverse variance as the statistical method under a random-effects model. We assessed the quality of evidence by outcome using the Grading of Recommendations Assessment, Development, and Evaluation approach. Results: Eligibility screening of 47 articles resulted in 9 included in the review. The overall methodologic quality was moderate. Meta-analysis of 5-HT3 RAs vs. placebo showed significant benefit for 5-HT3 RAs (relative risk [RR] 0.70; 95% confidence interval [CI] 0.57-0.86 for emesis; RR 0.84, 95% CI 0.73-0.96 for nausea). Meta-analysis comparing 5-HT3 RAs vs. metoclopramide showed a significant benefit of the 5-HT3 RAs for emetic control (RR 0.27, 95% CI 0.15-0.47). Conclusion: 5-Hydroxytryptamine-3 RAs are superior to placebo and other antiemetics for prevention of emesis, but little benefit was identified for nausea prevention. 5-Hydroxytryptamine-3 RAs are suggested for prevention of emesis. Limited evidence was found regarding delayed emesis, adverse events, quality of life, or need for rescue medication. Future randomized, controlled trials should evaluate different 5-HT3 antiemetics and new agents with novel mechanisms of action such at the NK

  11. Neurokinin-1 Receptor Antagonist-Based Triple Regimens in Preventing Chemotherapy-Induced Nausea and Vomiting: A Network Meta-Analysis.

    PubMed

    Zhang, Yaxiong; Yang, Yunpeng; Zhang, Zhonghan; Fang, Wenfeng; Kang, Shiyang; Luo, Youli; Sheng, Jin; Zhan, Jianhua; Hong, Shaodong; Huang, Yan; Zhou, Ningning; Zhao, Hongyun; Zhang, Li

    2017-02-01

    Neurokinin-1 receptor antagonists (NK-1RAs) are widely used for chemotherapy-induced nausea and vomiting (CINV) control in patients with highly emetogenic chemotherapy (HEC) and/or moderately emetogenic chemotherapy (MEC). Whether the efficacy and toxicity of antiemesis are different among various NK-1RA-based triple regimens is unknown. Data of complete responses (CRs) in the acute, delayed, and overall phases and treatment-related adverse events (TRAEs) were extracted from electronic databases. Efficacy and toxicity were integrated by pairwise and network meta-analyses. Thirty-six trials involving 18 889 patients using triple regimens (NK-1RA+serotonin receptor antagonists [5HT3RA] + dexamethasone) or duplex regimen (5HT3RA+dexamethasone) to control CINV were included in the analysis. Different NK-1RA-based triple regimens shared equivalent effect on CRs. In patients with HEC, almost all triple regimens showed statistically significantly higher CRs than duplex regimen (odds ratio [OR]duplex/triple = 0.47-0.66). However, in patients with MEC, only aprepitant-based triple regimen showed better effect than duplex regimen statistically significantly in CRs (ORduplex/triple = 0.52, 95% confidence interval [CI] = 0.34 to 0.68). No statistically significant difference of TRAEs was found among different triple regimens. Palonosetron-based triple regimens were equivalent to first-generation 5HT3RAs-based triple regimens for CRs. Moreover, different doses of dexamethasone plus NK-1RA and 5HT3RA showed no statistically significant difference in CRs. Different NK-1RAs-based triple regimens shared equivalent effect on CINV control. Various triple regimens had superior antiemetic effect than duplex regimen in patients with HEC. Only aprepitant-based triple regimen showed better CINV control compared with duplex regimen in patients receiving MEC. Palonosetron and first-generation 5HT3RAs might share equivalent CINV control in the combination of NK-1RAs and dexamethasone. Lower

  12. Simultaneous Determination of Dexamethasone, Ondansetron, Granisetron, Tropisetron, and Azasetron in Infusion Samples by HPLC with DAD Detection

    PubMed Central

    Chen, Fu-chao; Wang, Lin-hai; Guo, Jun; Shi, Xiao-ya

    2017-01-01

    A simple and rapid high-performance liquid chromatography with diode array detector (HPLC-DAD) method has been developed and validated for simultaneous quantification of five antiemetic agents in infusion samples: dexamethasone, ondansetron, granisetron, tropisetron, and azasetron. The chromatographic separation was achieved on a Phenomenex C18 column (4.6 mm × 150 mm, 5 μm) using acetonitrile-50 mM KH2PO4 buffer-triethylamine (25 : 74 : 1; v/v; pH 4.0). Flow rate was 1.0 mL/min with a column temperature of 30°C. Validation of the method was made in terms of specificity, linearity, accuracy, and intra- and interday precision, as well as quantification and detection limits. The developed method can be used in the laboratory to routinely quantify dexamethasone, ondansetron, granisetron, tropisetron, and azasetron simultaneously and to evaluate the physicochemical stability of referred drugs in mixtures for endovenous use. PMID:28168082

  13. Management of platinum-based chemotherapy-induced acute nausea and vomiting: is there a superior serotonin receptor antagonist?

    PubMed

    Hamadani, Mehdi; Chaudhary, Lubna; Awan, Farrukh T; Khan, Jawad K; Kojouri, Kiarash; Ozer, Howard; Tfayli, Arafat

    2007-06-01

    The last decade has witnessed the great impact of 5-hydroxytryptamine-3 receptor (5-HT(3))antagonists in revolutionizing the management of platinum-based chemotherapy-induced acute nausea and vomiting (CINV). However, despite the availability of a variety of 5-HT(3) antagonists, little data is published to support superiority of one drug over another, leaving the choice of serotonin receptor antagonist largely empirical. The National Comprehensive Cancer Network and American Society of Clinical Oncology guidelines for management of chemotherapy-associated nausea and vomiting cleary endorse the use of serotonin receptor antagonist; however, no single agent is preferred over the rest. Data for patients (n=159) receiving platinum-based chemotherapy regimens were retrospectively collected . Patients getting 5-HT(3) antagonists without steriods or those with known history of brain metastasis, gastroparesis, and intestinal obstruction were not eligible for the study. Patient characteristics including age, gender, primary diagnosis, history of heavy alcohol intake, chemotherapy regimen administered , number of cycles, and Eastern Cooperative Group performance status at the start of therapy were noted. Primary outcome was the complete control of platinum-induced acute nausea and vomiting. Secondary outcome measures included control of > or = grade 1 nausea or vomiting, comparison of two doses of dexamethasone, and antiemetic eficacy among various platinum drugs. National Cancer Institute Common Toxicity Criteria version 2.0 was used to assess toxicity. A total of 126 patients received 369 cycles of platinum-based therapy. Dolasetron ( n=157), granisetron ( n=81), and ondansetron ( n=131) achieved complete control of vomiting in 89.8, 95.5, and 92.3% (p=0.67) of cycles, respectively. Respectively, complete nausea control was observed in 68.1, 75.3 and, 69.4% (p=0.50). Dexamethasone 20 mg was not superior to 10 mg in complete control of nausea and vomiting ( p= 0.15 and p=0

  14. Re-examination for pharmacological properties of serotonin-induced tachycardia in isolated guinea-pig atrium.

    PubMed

    Nishio, H; Fujii, A; Nakata, Y

    1996-01-01

    In the presence of 10(-6) M atropine, 5-HT induced a positive chronotropic and inotropic effect in isolated guinea-pig atrium preparation. Both propranolol, a beta-adrenoceptor blocker, and imipramine, a 5-HT uptake inhibitor, did not affect the response induced by 5-HT, indicating that a tyramine-like mechanism is not involved. The positive chronotropic effect of 5-HT was mimicked by several 5-HT3 receptor agonists. N omega-Methyl-5-HT, reported to have a high affinity for 5-HT1B recognition sites, was found to act as a 5-HT3 receptor agonist with higher efficacy. The other 5-HT receptor agonists tested did not produced any responses. The positive chronotropic effect of 5-HT was inhibited by various 5-HT3 receptor antagonists, such as tropisetron, granisetron, ondansetron, cisapride and zacopride, but it was unaffected by various 5-HT receptor antagonists which are not selective for 5-HT3 receptor. Thus, the positive chronotropic response to 5-HT is a direct effect, and it was suggested to be mediated by 5-HT3 receptor subtype with rather an atypical profile.

  15. [Prophylaxis of chemotherapy-induced vomiting and nausea].

    PubMed

    Tóth, Judit; Szántó, János

    2008-12-01

    Chemotherapy-induced vomiting and nausea is the most common adverse event of anticancer therapy. In different guide-lines (MASCC, NCCN, ESMO and ASCO) antiemetic prophylaxis is directed toward the emetogenic potential of the chemotherapy and the type of vomiting and nausea. Chemotherapeutic agents are classified into four emetic risk groups: high, moderate, low, and minimal. Steroids, dexamethasone, metoclopramide, cannabinoids, benzodiazepines, 5-HT3 receptor antagonists (ondansetron, granisetron, tropisetron) and a new group of antiemetics, the neurokinin1 receptor antagonists are used to prevent anticipatory, acute and delayed vomiting and nausea. This paper examines evidence-based recommendations for optimal use of antiemetics.

  16. HPLC, TLC, and first-derivative spectrophotometry stability-indicating methods for the determination of tropisetron in the presence of its acid degradates.

    PubMed

    Abdel-Fattah, Laila S; El-Sherif, Zeinab A; Kilani, Khadiga M; El-Haddad, Dalia A

    2010-01-01

    Three stability-indicating assay methods were developed for the determination of tropisetron in a pharmaceutical dosage form in the presence of its degradation products. The proposed techniques are HPLC, TLC, and first-derivative spectrophotometry (1D). Acid degradation was carried out, and the degradation products were separated by TLC and identified by IR, NMR, and MS techniques. The HPLC method was based on determination of tropisetron in the presence of its acid-induced degradation product on an RP Nucleosil C18 column using methanol-water-acetonitrile-trimethylamine (65 + 20 + 15 + 0.2, v/v/v/v) mobile phase and UV detection at 285 nm. The TLC method was based on the separation of tropisetron and its acid-induced degradation products, followed by densitometric measurement of the intact spot at 285 nm. The separation was carried out on silica gel 60 F254 aluminum sheets using methanol-glacial acetic acid (22 + 3, v/v) mobile phase. The 1D method was based on the measurement of first-derivative amplitudes of tropisetron in H2O at the zero-crossing point of its acid-induced degradation product at 271.9 nm. Linearity, accuracy, and precision were found to be acceptable over concentration ranges of 40-240 microg/mL, 1-10 microg/spot, and 6-36 micro/mL for the HPLC, TLC, and 1D methods, respectively. The suggested methods were successfully applied for the determination of the drug in bulk powder, laboratory-prepared mixtures, and a commercial sample.

  17. Aryl biphenyl-3-ylmethylpiperazines as 5-HT7 receptor antagonists.

    PubMed

    Kim, Jeeyeon; Kim, Youngjae; Tae, Jinsung; Yeom, Miyoung; Moon, Bongjin; Huang, Xi-Ping; Roth, Bryan L; Lee, Kangho; Rhim, Hyewhon; Choo, Il Han; Chong, Youhoon; Keum, Gyochang; Nam, Ghilsoo; Choo, Hyunah

    2013-11-01

    The 5-HT7 receptor (5-HT7 R) is a promising therapeutic target for the treatment of depression and neuropathic pain. The 5-HT7 R antagonist SB-269970 exhibited antidepressant-like activity, whereas systemic administration of the 5-HT7 R agonist AS-19 significantly inhibited mechanical hypersensitivity and thermal hyperalgesia. In our efforts to discover selective 5-HT7 R antagonists or agonists, aryl biphenyl-3-ylmethylpiperazines were designed, synthesized, and biologically evaluated against the 5-HT7 R. Among the synthesized compounds, 1-([2'-methoxy-(1,1'-biphenyl)-3-yl]methyl)-4-(2-methoxyphenyl)piperazine (28) was the best binder to the 5-HT7 R (pKi =7.83), and its antagonistic property was confirmed by functional assays. The selectivity profile of compound 28 was also recorded for the 5-HT7 R over other serotonin receptor subtypes, such as 5-HT1 R, 5-HT2 R, 5-HT3 R, and 5-HT6 R. In a molecular modeling study, the 2-methoxyphenyl moiety attached to the piperazine ring of compound 28 was proposed to be essential for the antagonistic function.

  18. Fosaprepitant: a neurokinin-1 receptor antagonist for the prevention of chemotherapy-induced nausea and vomiting.

    PubMed

    Navari, Rudolph M

    2008-11-01

    Chemotherapy-induced nausea and vomiting (CINV) is a distressing and common adverse event associated with cancer treatment. Updated antiemetic guidelines were published in 2008 by the National Comprehensive Cancer Network and, in 2006, by the American Society of Clinical Oncology, which have included the use of the new and more effective antiemetic agents 5-hydroxytryptamine-3 (5-HT(3)) receptor antagonist and neurokinin (NK)-1 receptor antagonist. Aprepitant is a selective NK-1 receptor antagonist approved as part of combination therapy with a corticosteroid and a 5-HT(3) receptor antagonist for the prevention of acute and delayed CINV in patients receiving moderately and highly emetogenic chemotherapy. Fosaprepitant (also known as MK-0517 and L-758,298) is a water-soluble phosphoryl prodrug for aprepitant, which, when administered intravenously, is converted to aprepitant within 30 min of intravenous administration via the action of ubiquitous phosphatases. Owing to the rapid conversion of fosaprepitant to the active form (aprepitant), fosaprepitant 115 mg provided the same aprepitant exposure in terms of AUC as aprepitant 12 mg orally, and fosaprepitant is expected to provide a correspondingly similar antiemetic effect as aprepitant. Clinical studies have suggested that fosaprepitant could be appropriate as an intravenous alternative to the aprepitant oral capsule. In a study in healthy subjects, fosaprepitant 115 mg was generally well tolerated at a final drug concentration of 1 mg/ml, and fosaprepitant 115 mg was AUC bioequivalent to aprepitant 125 mg. Fosaprepitant in the dose of 115 mg has been approved by the US FDA, the EU and the Australian authorities on day 1 of a 3-day oral aprepitant regimen, with oral aprepitant administered on days 2 and 3. Fosaprepitant may be a useful parenteral alternative to oral aprepitant. Further study is needed to clarify the utility of fosaprepitant in the prevention of CINV and to clarify optimal dosing regimens that may

  19. Mechanisms linking depression co-morbid with obesity: An approach for serotonergic type 3 receptor antagonist as novel therapeutic intervention.

    PubMed

    Kurhe, Yeshwant; Mahesh, Radhakrishnan

    2015-10-01

    Despite of the enormous research, therapeutic treatment for depression has always been a serious issue. Even though depression and obesity are individual abnormal health conditions, each act as a triggering factor for the other. Obese individuals are twice prone to develop depression than that of non-obese persons. The exact mechanism how obesity increases the risk for depression still remains an area of interest for research in neuropsychopharmacology. Depression and obesity share some common pathological pathways such as hyperactivity of hypothalamic-pituitary-adrenal (HPA) axis, dysregulation of oxidant/antioxidant system balance, higher level of inflammatory cytokines, leptin resistance, altered plasma glucose, insulin resistance, reduced neuronal brain derived neurotrophic factor (BDNF) and decreased serotonergic neurotransmission in various regions of brain. The antidepressant-like effect of 5-HT3 receptor antagonists through allosteric modulation of serotonergic pathways is well evident from several research investigations belonging to our and some in other laboratories. Furthermore, serotonin regulates diet intake, leptin, corticosterone, inflammatory mechanisms, altered plasma glucose, insulin resistance and BDNF concentration in brain. The present review deals with various biological mechanisms involved in depression co-morbid with obesity and 5-HT3 receptor antagonists by modulation of serotonergic system as a therapeutic target for such co-morbid disorder. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Selective corticotropin-releasing factor 1 receptor antagonist E2508 reduces restraint stress-induced defecation and visceral pain in rat models.

    PubMed

    Taguchi, Ryota; Shikata, Kodo; Furuya, Yoshiaki; Hirakawa, Tetsuya; Ino, Mitsuhiro; Shin, Kogyoku; Shibata, Hisashi

    2017-01-01

    N-Cyclopropylmethyl-7-(2,6-dimethoxy-4-methoxymethylphenyl)-2-ethyl-N-(tetrahydro-2H-pyran-4-ylmethyl)pyrazolo[1,5-a]pyridin-3-amine tosylate (E2508) is a newly discovered selective corticotropin-releasing factor 1 receptor antagonist. Here, we investigated the effects of E2508 on wrap restraint stress-induced defecation and visceral pain in rats. Oral pretreatment with E2508 dose-dependently decreased stool weights after 20min wrap restraint stress and significant effects were observed at doses of 30 and 100mg/kg. However, E2508 did not affect basal defecation at doses up to 100mg/kg. In contrast, alosetron, a 5-HT3 receptor antagonist, decreased both wrap restraint stress-induced and basal stool output at a dose of 0.1mg/kg. In a rat visceral pain model, subcutaneous injections of both E2508 (0.01 and 0.1mg/kg) and alosetron (0.001 and 0.01mg/kg) significantly decreased the number of abdominal muscle contractions induced by colonic distention, suggesting these drugs reduced visceral pain. Together, these results demonstrate E2508 has the potential to be an effective therapy for the treatment of irritable bowel syndrome with a lower risk of adverse events such as constipation compared with the current clinically used 5-HT3 receptor antagonist.

  1. Nanoethosomes for transdermal delivery of tropisetron HCl: multi-factorial predictive modeling, characterization, and ex vivo skin permeation.

    PubMed

    Abdel Messih, Hanaa A; Ishak, Rania A H; Geneidi, Ahmed S; Mansour, Samar

    2017-06-01

    The aim of the present work is to exclusively optimize and model the effect of phospholipid type either egg phosphatidylcholine (EPC) or soybean phosphatidylcholine (SPC), together with other formulation variables, on the development of nano-ethosomal systems for transdermal delivery of a water-soluble antiemetic drug. Tropisetron HCl (TRO) is available as hard gelatin capsules and IV injections. The transdermal delivery of TRO is considered as a novel alternative route supposing to improve BAV as well as patient convenience. TRO-loaded ethanolic vesicular systems were prepared by hot technique. The effect of formulation variables were optimized through a response surface methodology using 3 × 2(2)-level full factorial design. The concentrations of both PC (A) and ethanol (B) and PC type (C) were the factors, while entrapment efficiency (Y1), vesicle size (Y2), polydispersity index (Y3), and zeta potential (Y4) were the responses. The drug permeation across rat skin from selected formulae was studied. Particle morphology, drug-excipient interactions, and vesicle stability were also investigated. The results proved the critical role of all formulation variables on ethosomal characteristics. The suggested models for all responses showed good predictability. Only the concentration of phospholipid, irrespective to PC type, had a significant effect on the transdermal flux (p < 0.01). The ethosomal vesicles were unilamellar with a nearly spherical shape. EPC-based ethosomes proved good stability. The study suggests the applicability of statistical modeling as a promising tool for prediction of ethosomal characteristics. The ethanolic vesicles were considered as novel potential nanocarriers for accentuated transdermal TRO delivery.

  2. Kisspeptin antagonists.

    PubMed

    Roseweir, Antonia Kathryn; Millar, Robert P

    2013-01-01

    Kisspeptin is now known to be an important regulator of the hypothalamic--pituitary-gonadal axis and is the target of a range of regulators, such as steroid hormone feedback, nutritional and metabolic regulation. Kisspeptin binds to its cognate receptor, KISS1R (also called GPR54), on GnRH neurons and stimulates their activity, which in turn provides an obligatory signal for GnRH secretion-thus gating down-stream events supporting reproduction. The development of peripherally active kisspeptin antagonists could offer a unique therapeutic agent for treating hormone-dependent disorders of reproduction, including precocious puberty, endometriosis, and metastatic prostate cancer. The following chapter discusses the advances made in the search for both peptide and small molecule kisspeptin antagonists and their use in delineating the role of kisspeptin within the reproductive system. To date, four peptide antagonists and one small molecule antagonist have been designed.

  3. 5-HT receptors involved in opioid-activated descending inhibition of spinal withdrawal reflexes in the decerebrated rabbit.

    PubMed

    Lo, W Caroline; Jackson, Elizabeth; Merriman, Andrew; Harris, John; Clarke, Rob W

    2004-05-01

    The role of 5-HT(1B/1D), 5-HT(2) and 5-HT(3) receptors in mediating descending inhibition of spinal reflexes activated by application of fentanyl to the fourth ventricle has been studied in rabbits decerebrated under N(2)O/isoflurane anaesthesia. In the control state, intraventricular fentanyl (3-30 microg kg(-1)) depressed, to an equal extent, short- and long-latency reflexes in the medial gastrocnemius muscle nerve evoked by electrical stimulation of all sural nerve afferents. Inhibition of reflexes resulted from a decreased base line excitability in the reflex pathway accompanied by a reduction in the rate of temporal summation of responses. Fentanyl-induced suppression of short- and long-latency reflexes was significantly reduced after intrathecal administration of the selective 5-HT(2)-receptor antagonist ICI 170,809 (300 microg). The same dose of the selective 5-HT(1B/1D) blocker GR 127,935 reduced inhibition from intraventricular fentanyl only for long-latency reflexes (i.e. those parts of the response for which the afferent drive is provided mainly by Adelta and C-fibre afferents). The 5-HT(3) antagonist tropisetron (also 300 microg intrathecal) did not significantly alter the descending inhibition of reflexes evoked by fentanyl. Both GR 127,935 and tropisetron reduced temporal summation of reflexes per se, effects that were reversed by intraventricular fentanyl. These data suggest that the descending pathway(s) activated by intraventricular fentanyl liberate 5-HT in the spinal cord to inhibit withdrawal reflexes by acting at 5-HT(2) and 5-HT(1B/1D), but not 5-HT(3) receptors. 5-HT(1B/1D), and to a lesser extent 5-HT(3) receptors also appear to have a role in modulating temporal summation of reflexes evoked by repetitive stimuli.

  4. The pharmacology of the 5-HT4 receptor.

    PubMed

    Costall, B; Naylor, R J

    1993-11-01

    Dumuis and colleagues (1988) in their investigation of a 5-HT receptor positively linked to adenylate cyclase in the central nervous system, concluded that the receptor was not 5-HT1, 5-HT2 or 5-HT3-like and suggested that it belonged to a new class of 5-HT receptor called 5-HT4. A similar, if not identical receptor was located by Craig and Clark (1990) in the guinea pig ileum and a functional role for the peripheral 5-HT4 receptor has since been established in many species to mediate muscle contraction or relaxation within the gut and positive inotropic effects in the heart. In contrast, a functional role for central 5-HT4 receptors has remained obscure. Using measurements of rodent behaviour in the mouse light and dark test box and rat social interaction, anxiolytic agents such as diazepam and putative anxiolytic agents such as the 5-HT1A and 5-HT3 receptor ligands 8-OH-DPAT and low doses of tropisetron release behaviour suppressed by the aversive situation. 5-Hydroxytryptophan has the opposite effect exacerbating the behavioural response to the aversive situation. But an anxiolytic profile is revealed by co-treatment with ritanserin plus 5-hydroxytryptophan. The drug-induced anxiolytic profiles are inhibited by SDZ205-557 and a high dose of tropisetron. Both compounds are 5-HT3/5-HT4 receptor antagonists yet the selective 5-HT3 receptor antagonist ondansetron fails to inhibit the drug-induced anxiolytic profiles.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. Casopitant: a novel NK1-receptor antagonist in the prevention of chemotherapy-induced nausea and vomiting

    PubMed Central

    Ruhlmann, Christina; Herrstedt, Jørn

    2009-01-01

    Chemotherapy-induced nausea and vomiting (CINV) are among the most feared and distressing symptoms experienced by patients with cancer. The knowledge of the pathogenesis and neuropharmacology of CINV has expanded enormously over the last decades, the most significant discoveries being the role of 5-hydroxytryptamine (5-HT)3- and neurokinin (NK)1 receptors in the emetic reflex arch. This has led to the development of two new classes of antiemetics acting as highly selective antagonists at one of these receptors. These drugs have had a huge impact in the protection from chemotherapy-induced vomiting, whereas the effect on nausea seems to be limited. The first NK1 receptor antagonist, aprepitant, became clinically available in 2003, and casopitant, the second in this class of antiemetics, has now completed phase III trials. This review delineates the properties and clinical use of casopitant in the prevention of CINV. PMID:19536319

  6. Fosaprepitant (MK-0517): a neurokinin-1 receptor antagonist for the prevention of chemotherapy-induced nausea and vomiting.

    PubMed

    Navari, Rudolph M

    2007-12-01

    Chemotherapy-induced nausea and vomiting (CINV) is a distressing and common adverse event associated with cancer treatment. Updated anti-emetic guidelines were published in 2007 by the National Comprehensive Cancer Network and in 2006 by the American Society of Clinical Oncology, which have included the use of the new and more effective anti-emetic agents (5-hydroxytryptamine-3 [5-HT(3)] receptor antagonists and neurokinin-1 [NK-1] receptor antagonists). Aprepitant is a selective NK-1 receptor antagonist approved as part of combination therapy with a corticosteroid and a 5-HT(3) receptor antagonist for the prevention of acute and delayed CINV. Fosaprepitant (also known as MK-0517 and L-758,298) is a water-soluble phosphoryl prodrug for aprepitant, which, when administered intravenously, is converted to aprepitant within 30 min after intravenous administration via the action of ubiquitous phosphatases. Because fosaprepitant is rapidly converted to the active form (aprepitant), it is expected to provide the same aprepitant exposure in terms of AUC, and a correspondingly similar anti-emetic effect. Clinical studies have suggested that fosaprepitant could be appropriate as an intravenous alternative to the aprepitant oral capsule. In a study in healthy subjects, fosaprepitant was well tolerated up to 150 mg (1 mg/ml), and fosaprepitant 115 mg was bioequivalent in its AUC to aprepitant 125 mg. Fosaprepitant 115 mg has been submitted for FDA approval as an alternative on day 1 of a 3-day oral aprepitant regimen, with oral aprepitant administered on days 2 and 3. Fosaprepitant may be a useful parenteral alternative to oral aprepitant. Further study is needed to clarify the use of fosaprepitant for the prevention of CINV, and to clarify optimal dosing regimens that may be appropriate substitutes for oral aprepitant.

  7. Multiple 5-HT receptors in the guinea-pig superior cervical ganglion.

    PubMed Central

    Watkins, C. J.; Newberry, N. R.

    1996-01-01

    1. We have studied the pharmacology of the depolarization by 5-hydroxytryptamine (5-HT) of the guinea-pig isolated superior cervical ganglion (SCG) using the grease-gap technique. We studied the effects of selective and non-selective antagonists on the responses to 5-HT and other 5-HT receptor agonists. 2. We have extended the pharmacology of the 5-HT3 receptor in this preparation by studying the effects of granisetron, BRL 46470 and mianserin on the concentration-response curve (CRC) to 2-methyl-5-HT. As with other 5-HT3 receptor antagonists, these compounds exhibited a lower affinity for guinea-pig 5-HT3 receptors than for rat 5-HT3 receptors. 3. We have confirmed that low concentrations of 5-HT (< or = 1 microM) mediate ketanserin-sensitive responses and higher concentrations of 5-HT also recruit 5-HT3 receptors. The responses to low concentrations of 5-HT were antagonized by low concentrations of ketanserin, spiperone, mianserin, DOI and LSD indicating probably mediation by 5-HT2A receptors. At high concentrations, the hallucinogen, DOI, but not LSD, evoked a ketanserin-sensitive depolarization. 4. Although mianserin could bind to the 5-HT2A receptors in this preparation, we could not demonstrate a down-regulation of depolarizations evoked by these receptors after a 10 day oral treatment with mianserin (10 mg kg-1, daily). 5. 5-Carboxamidotryptamine (5-CT) evoked a prolonged depolarization. Although high concentrations of 5-CT (> or = microM) appeared to activate 5-HT2A receptors, lower concentrations of 5-CT evoked a response with a distinct pharmacology. After studying the action of 20 selective and non-selective 5-HT receptor ligands we believe that this response may be mediated by a novel receptor; but its pharmacology is closest to that of receptors in the 5-HT2 receptor family. Like 5-CT, 5-HT (3-300 microM) could evoke an LSD-sensitive response in the presence of the 5-HT2 receptor antagonist, ketanserin and the 5-HT3 receptor antagonist, tropisetron

  8. Actions of 5-hydroxytryptophan to inhibit and disinhibit mouse behaviour in the light/dark test.

    PubMed

    Cheng, C H; Costall, B; Kelly, M E; Naylor, R J

    1994-04-01

    The involvement of 5-HT receptors in behavioural responding to an aversive situation was investigated in the mouse light/dark test. The administration of 5-hydroxytryptophan (5-HTP) (12.5-50 mg/kg i.p.) increased brain 5-HT turnover and inhibited mouse behaviour in the light/dark test box. The 5-HT2C/5-HT2A receptor antagonists methysergide (1.0 and 5.0 mg/kg i.p.) and ritanserin (0.1-1.0 mg/kg i.p.) antagonised (methysergide) or reversed (ritanserin) the effects of 5-HTP to an increased exploration of the light compartment; a low dose of the 5-HT3 receptor antagonist ondansetron (0.01 mg/kg i.p.) had a similar effect. The disinhibitory effect of the 5-HTP/ritanserin interaction was antagonised by the 5-HT3/5-HT4 receptor antagonists SDZ205-557 (0.001-0.1 mg/kg) and a high dose of tropisetron (1.0 mg/kg i.p.) but not by ondansetron (1.0 mg/kg i.p.). At these doses tropisetron and ondansetron had no effect in their own right. Thus the dominant effect of 5-HTP in the mouse is to inhibit behaviour, a response mediated via 5-HT2C/5-HT2A and 5-HT3 receptors. A 5-HT4 receptor may effect an opposing disinhibitory potential as revealed by ritanserin.

  9. ACTH Antagonists

    PubMed Central

    Clark, Adrian John; Forfar, Rachel; Hussain, Mashal; Jerman, Jeff; McIver, Ed; Taylor, Debra; Chan, Li

    2016-01-01

    Adrenocorticotropin (ACTH) acts via a highly selective receptor that is a member of the melanocortin receptor subfamily of type 1 G protein-coupled receptors. The ACTH receptor, also known as the melanocortin 2 receptor (MC2R), is unusual in that it is absolutely dependent on a small accessory protein, melanocortin receptor accessory protein (MRAP) for cell surface expression and function. ACTH is the only known naturally occurring agonist for this receptor. This lack of redundancy and high degree of ligand specificity suggests that antagonism of this receptor could provide a useful therapeutic aid and a potential investigational tool. Clinical situations in which this could be useful include (1) Cushing’s disease and ectopic ACTH syndrome – especially while preparing for definitive treatment of a causative tumor, or in refractory cases, or (2) congenital adrenal hyperplasia – as an adjunct to glucocorticoid replacement. A case for antagonism in other clinical situations in which there is ACTH excess can also be made. In this article, we will explore the scientific and clinical case for an ACTH antagonist, and will review the evidence for existing and recently described peptides and modified peptides in this role. PMID:27547198

  10. Efficacy benefit of an NK1 receptor antagonist (NK1RA) in patients receiving carboplatin: supportive evidence with NEPA (a fixed combination of the NK1 RA, netupitant, and palonosetron) and aprepitant regimens.

    PubMed

    Jordan, Karin; Gralla, Richard; Rizzi, Giada; Kashef, Kimia

    2016-11-01

    Antiemetic guideline recommendations are inconsistent as to whether a neurokinin-1 receptor antagonist (NK1 RA) should be administered with a 5-hydroxytryptamine-3 (5HT3) RA + dexamethasone (DEX) in patients receiving carboplatin. Patients receiving cisplatin routinely receive an NK1 RA-containing regimen with a resulting 14-22 % benefit in no emesis rates over a 5-HT3 RA/DEX control. Recent studies suggest a similar benefit in patients receiving carboplatin. NEPA is the first fixed antiemetic combination agent and comprises the highly selective NK1 RA, netupitant, and pharmacologically distinct 5-HT3 RA, palonosetron (PALO). This paper presents the efficacy of NEPA in the subset of patients receiving carboplatin in a phase 3 trial (NCT01376297), in the context of aprepitant (APR) data in the carboplatin setting. One hundred ninety-six patients (47 % of all study patients: n = 145 NEPA + DEX; n = 51 APR + PALO + DEX) received carboplatin in a multinational, double-blind, randomized phase 3 study. Complete response (CR: no emesis/rescue) and no significant nausea (NSN: score ≤25 on 100 mm visual analog scale) rates were calculated. Cycle 1-4 overall (0-120 h) CR rates were similar for NEPA (80, 91, 92, and 93 %) and APR (82, 88, 88, and 90 %). Overall NSN rates were also similar (NEPA 84-96 %; APR 82-90 %). Response rates for NEPA and APR regimens were similar and consistent with prior studies evaluating the contribution of adding NK1 RAs in patients receiving carboplatin. Considering such evidence, guideline groups/practitioners should consider giving a NK1 RA antiemetic triplet in patients receiving carboplatin.

  11. Neurokinin-1 receptor antagonists for chemotherapy-induced nausea and vomiting: a systematic review.

    PubMed

    dos Santos, Lucas Vieira; Souza, Fabiano Hahn; Brunetto, Andre Tesainer; Sasse, Andre Deeke; da Silveira Nogueira Lima, João Paulo

    2012-09-05

    The addition of neurokinin-1 receptor (NK1R) antagonists to antiemetic regimens has substantially reduced chemotherapy-induced nausea and vomiting (CINV). We sought to systematically review the overall impact of NK1R antagonists on CINV prevention. We systematically searched the MEDLINE, EMBASE, and CENTRAL databases, and meeting proceedings for randomized controlled trials (RCTs) that evaluated NK1R antagonists plus standard antiemetic therapy for CINV prevention. Complete response (CR) to therapy was defined as the absence of emesis and the absence of rescue therapy. The endpoints were defined as CR in the overall phase (during the first 120 hours of chemotherapy), CR in the acute phase (first 24 hours), and the delayed phase (24-120 hours) after chemotherapy, nausea, and toxicity. Subgroup analyses evaluated the type of NK1R antagonist used, the emetogenic potential of the chemotherapy regimen, and prolonged use of 5-HT3 (serotonin) receptor antagonists, a class of standard antiemetic agents. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random-effects model. Statistical tests for heterogeneity were one-sided; statistical tests for effect estimates and publication bias were two-sided. Seventeen trials (8740 patients) were included in this analysis. NK1R antagonists increased the CR rate in the overall phase from 54% to 72% (OR = 0.51, 95% CI = 0.46 to 0.57, P < .001). CR and nausea were improved in all phases and subgroups. The expected side effects from NK1R antagonists did not statistically significantly differ from previous reports; however, this analysis suggests that the incidence of severe infection increased from 2% to 6% in the NK1R antagonist group (three RCTs with a total of 1480 patients; OR = 3.10; 95% CI = 1.69 to 5.67, P < .001). NK1R antagonists increased CINV control in the acute, delayed, and overall phases. They are effective for both moderately and highly emetogenic chemotherapy regimens. Their use might be

  12. Intestinal serotonin acts as a paracrine substance to mediate vagal signal transmission evoked by luminal factors in the rat

    PubMed Central

    Zhu, J X; Wu, X Y; Owyang, C; Li, Y

    2001-01-01

    The vagus nerve conveys primary afferent information produced by a meal to the brainstem. Serotonin (5-HT), which abounds in intestinal enterochromaffin cells, is released in response to various stimuli. We have recently demonstrated that 5-HT released from intestinal enterochromaffin cells activates 5-HT3 receptors on vagal afferent fibres to mediate luminal non-cholecystokinin-stimulated pancreatic secretion. The present study was designed to evaluate the responses of vagal sensory neurons to intraluminal osmotic stimulation and luminal infusion of maltose, glucose or 5-HT. We investigated the role of endogenous 5-HT in signal transmission evoked by luminal stimuli to activate vagal sensory neurons. The discharges of vagal primary afferent neurons innervating the intestine were recorded from rat nodose ganglia. Luminal factors such as intestinal osmotic stimuli and perfusion of carbohydrates elicited powerful vagal nodose responses. Electrical subdiaphragmatic vagal stimulation activated 364 single units; 40 of these responded to intestinal mucosal stimuli. Of these 40, 30 responded to intraduodenal perfusion of hyperosmolar NaCl (500 mosmol l−1), 27 responded to tap water (5 mosmol l−1) and 20 and 19 responded to maltose (300 mM) and glucose (277.5 mM), respectively. The 5-HT3/4 antagonist tropisetron (ICS 205-930) or 5-HT3 antagonist granisetron abolished luminal stimuli-evoked nodose neuronal responses. Intraluminal infusion of 10−5 and 10−4 M 5-HT elicited increases in vagal afferent discharge in 25 and 31 units, respectively, by activating the 5-HT3 receptors. Acute subdiaphragmatic vagotomy, intestinal mucosal application of the local anaesthetic lidocaine (lignocaine) or administration of 5-HT3 antagonist each abolished the luminal 5-HT-induced nodose neuronal responses. In contrast, distension-sensitive neurons did not respond to duodenal infusion of 5-HT. Pharmacological depletion of 5-HT stores using p-chlorophenylalanine (PCPA), a 5-HT

  13. Cardiovascular effects of selective agonists and antagonists of histamine H3 receptors in the anaesthetized rat.

    PubMed

    Coruzzi, G; Gambarelli, E; Bertaccini, G; Timmerman, H

    1995-06-01

    The cardiovascular responses to a series of selective histamine H3 receptor agonists, (R) alpha-methylhistamine, imetit and immepip and selective antagonists, thioperamide, clobenpropit and clophenpropit, were studied in anaesthetized rats. At 0.003-1 mumol/kg i.v. doses, H3 agonists failed to produce any significant change in the basal blood pressure and heart rate. Larger doses of (R) alpha-methylhistamine increased the blood pressure and heart rate and higher doses of imetit caused vasodepressor responses and reduced heart rate, whereas immepip proved virtually inactive. While (R) alpha-methylhistamine-induced effects were not blocked by histamine H1-, H2- and H3-receptor antagonists, they were however reduced by idazoxan and propranolol, which indicates that the mechanisms involved are adrenergic. The effects induced by imetit are not related to histamine H3 receptors but are mediated by indirect (via 5HT3 receptors) cholinergic mechanisms, since these effects were prevented by 1 mg/kg i.v. atropine and by 0.1 mg/kg i.v. ondansetron. Similarly, the H3 antagonists per se failed to change basal cardiovascular function up to 10 mumol/kg i.v. and only at 30 mumol/kg i.v. were marked decreases observed in the blood pressure and heart rate with a significant reduction in the effects of noradrenaline. These data indicate that in anaesthetized rats, histamine H3 receptor activation or blockade has no effect on basal cardiovascular function. The effects recorded after the administration of large doses of (R) alpha-methylhistamine and imetit are clearly unrelated to histamine H3 receptors and should be taken into account when using these compounds as H3 ligands for "in vivo" experiments.

  14. Effects of the 5-HT(6) receptor antagonist Ro 04-6790 on learning consolidation.

    PubMed

    Meneses, A

    2001-01-08

    The 5-HT(6) receptor antagonist Ro-04-6790 or 8-OH-DPAT injection improved learning consolidation on an autoshaping task, while mCPP, scopolamine and dizocilpine decreased the performance. The effect induced by scopolamine, but not that induced by mCPP, was reversed completely by Ro-04-6790, while dizocilpine effect was antagonized partially. Nevertheless, ritanserin or WAY 100635, but not Ro 04-6790, antagonized the 8-OH-DPAT facilitatory effects on learning consolidation. As WAY 100635 did not modify the Ro 04-6790 facilitatory effect, hence 5-HT(1A), and/or 5-HT(7), but not 5-HT(6), receptors might mediate the 8-OH-DPAT facilitatory effect on learning consolidation. Since, the Ro 04-6790 facilitatory effect was unaffected by 5-HT(1A), 5-HT(2A)/(2B)/(2C), 5-HT(3) or 5-HT(4) receptor blockade, thereby, the facilitatory effect induced by Ro 04-6790 involved specifically 5-HT(6) receptors. Indeed, the present data provide further support to the notion that, 5-HT(6) receptors play a significant part in the learning consolidation under normal and dysfunctional memory conditions.

  15. Fosaprepitant dimeglumine (MK-0517 or L-785,298), an intravenous neurokinin-1 antagonist for the prevention of chemotherapy induced nausea and vomiting.

    PubMed

    Van Belle, Simon Jp; Cocquyt, Veronique

    2008-12-01

    This paper reviews the existing literature on fosaprepitant, an intravenous neurokinin-1 anatgonist for the prevention of chemotherapy induced nausea and vomiting. To describe the development of fosaprepitant and to situate the intravenous form of aprepitant in the current market of available antiemetics. Literature was screened and selected in order to compare the intravenous form of the already commonly used NK-1 receptor antagonist aprepitant. Aprepitant is the first and still the only marketed neurokinin-1 (NK-1) antagonist. Interestingly, the first studies were performed with fosaprepitant dimeglumine (MK-0517 or L-785,298), the water-soluble prodrug of aprepitant. Fosaprepitant is converted into aprepitant within 30 min after intravenous administration. Based on equivalence studies, 115 mg fosaprepitant seems to be the substitute for 125 mg orally administrated aprepitant. Tolerability of the prodrug is no different from the active drug. The number of efficacy studies with fosaprepitant is very limited and most data are derived from existing aprepitant results. Fosaprepitant has recently been approved by FDA and EMEA as an intravenous substitute for oral aprepitant on day 1 of the standard 3-day CINV prevention regimen, which also includes dexamethasone and a 5-HT3 antagonist.

  16. 2016 updated MASCC/ESMO consensus recommendations: Prevention of acute chemotherapy-induced nausea and vomiting in children.

    PubMed

    Dupuis, L Lee; Sung, Lillian; Molassiotis, Alexander; Orsey, Andrea D; Tissing, Wim; van de Wetering, Marianne

    2017-01-01

    To update the 2009 recommendations for the prevention of acute chemotherapy-induced emesis in children. We updated the original systematic literature search. Randomized studies were included in the evidence to support this guideline if they were primary studies fully published in full text in English or French; included only children less than 18 years old or, for mixed studies of adults and children, reported the pediatric results separately or the median or mean age was no more than 13 years; evaluated acute chemotherapy-induced nausea and vomiting (CINV) prophylaxis; provided sufficient information to permit determination of the emetogenicity of the antineoplastic therapy administered or the study investigators stated the emetogenicity of the chemotherapy administered; included an implicit or explicit definition of complete acute CINV response; described the antiemetic regimen in full; and reported the complete acute CINV response rate as a proportion. Twenty-five randomized studies, including eight published since 2009, met the criteria for inclusion in this systematic review. Prophylaxis with a 5-HT3 antagonist (granisetron or ondansetron or palonosetron or tropisetron) ± dexamethasone ± aprepitant is recommended for children receiving highly or moderately emetogenic chemotherapy. For children receiving chemotherapy of low emetogenicity, a 5-HT3 antagonist is recommended. The findings of several randomized trials were used to update recommendations for the prevention of acute CINV. However, significant research gaps remain and must be addressed before CINV control in children can be optimized.

  17. Muscarinic Receptor Antagonists.

    PubMed

    Matera, Maria Gabriella; Cazzola, Mario

    2017-01-01

    Parasympathetic activity is increased in patients with chronic obstructive pulmonary disease (COPD) and asthma and appears to be the major reversible component of airway obstruction. Therefore, treatment with muscarinic receptor antagonists is an effective bronchodilator therapy in COPD and also in asthmatic patients. In recent years, the accumulating evidence that the cholinergic system controls not only contraction by airway smooth muscle but also the functions of inflammatory cells and airway epithelial cells has suggested that muscarinic receptor antagonists could exert other effects that may be of clinical relevance when we must treat a patient suffering from COPD or asthma. There are currently six muscarinic receptor antagonists licenced for use in the treatment of COPD, the short-acting muscarinic receptor antagonists (SAMAs) ipratropium bromide and oxitropium bromide and the long-acting muscarinic receptor antagonists (LAMAs) aclidinium bromide, tiotropium bromide, glycopyrronium bromide and umeclidinium bromide. Concerns have been raised about possible associations of muscarinic receptor antagonists with cardiovascular safety, but the most advanced compounds seem to have an improved safety profile. Further beneficial effects of SAMAs and LAMAs are seen when added to existing treatments, including LABAs, inhaled corticosteroids and phosphodiesterase 4 inhibitors. The importance of tiotropium bromide in the maintenance treatment of COPD, and likely in asthma, has spurred further research to identify new LAMAs. There are a number of molecules that are being identified, but only few have reached the clinical development.

  18. Role of the 5HT3 Receptor in Alcohol Drinking and Aggression Using a Transgenic Mouse Model

    DTIC Science & Technology

    2006-09-01

    regions such as the hippocampus and amygdala, demonstrating that expression of genes can be influenced by maternal behavior (Francis et al. 1999...Aggressive behavior and altered amounts of brain serotonin and norepinephrine in mice lacking MAOA . Science 268:1763-6. Coccaro EF, Astill JL, Herbert

  19. Role of the 5HT3 Receptor in Alcohol Drinking and Aggression Using A Transgenic Mouse Model

    DTIC Science & Technology

    2005-09-01

    female rats have changes in mRNA in regions such as the hippocampus and amygdala, demonstrating that expression of genes can be influenced by maternal...norepinephrine in mice lacking MAOA . Science 268:1763-6. Coccaro EF, Astill JL, Herbert JL, and Schut AG. Fluoxetine Treatment of Impulsive Aggression in DSM

  20. Emesis and Defecations Induced by the 5-Hydroxytryptamine (5-HT3) Receptor Anatagonist Zacopride in the Ferret

    DTIC Science & Technology

    1990-02-16

    vehicle pretreatment in order screened for evidence of disease prior to release from quarantine- to re-establish that a response to zacopride would occur...dorsal vagus primarily innervates the dorsal aspects reported here (n.033 mg/kg). In contrast, Costall et al. (1987) of the stomach and the coeliac ...receptor. This was anatomically beyond the coeliac ganglion (MacKay and An- demonstrated by the reduced emesis seen after pretreatment drews, 1983

  1. AHR-16303B, a novel antagonist of 5-HT2 receptors and voltage-sensitive calcium channels

    SciTech Connect

    Barrett, R.J.; Appell, K.C.; Kilpatrick, B.F.; Proakis, A.G.; Nolan, J.C.; Walsh, D.A. )

    1991-01-01

    In vivo and in vitro methods were used to characterize AHR-16303B, a novel compound with antagonistic action at 5-HT2 receptors and voltage-sensitive calcium channels. The 5-HT2 receptor-antagonistic properties of AHR-16303B were demonstrated by inhibition of (a) (3H)ketanserin binding to rat cerebral cortical membranes (IC50 = 165 nM); (b) 5-hydroxytryptamine (5-HT)-induced foot edema in rats (minimum effective dose, (MED) = 0.32 mg/kg orally, p.o.); (c) 5-HT-induced vasopressor responses in spontaneously hypertensive rats (SHR) (ID50 = 0.18 mg/kg intravenously (i.v.), 1.8 mg/kg p.o.), (d) 5-HT-induced antidiuresis in rats (MED = 1 mg/kg p.o.), and (e) platelet aggregation induced by 5-HT + ADP (IC50 = 1.5 mM). The calcium antagonist properties of AHR-16303B were demonstrated by inhibition of (a) (3H)nimodipine binding to voltage-sensitive calcium channels on rabbit skeletal muscle membranes (IC50 = 15 nM), (b) KCl-stimulated calcium flux into cultured PC12 cells (IC50 = 81 nM), and (c) CaCl2-induced contractions of rabbit thoracic aortic strips (pA2 = 8.84). AHR-16303B had little or no effect on binding of radioligands to dopamine2 (DA2) alpha 1, alpha 2, H1, 5-HT1 alpha, beta 2, muscarinic M1, or sigma opioid receptors; had no effect on 5-HT3 receptor-mediated vagal bradycardia; and had only minor negative inotropic, chronotropic, and dromotropic effects on isolated guinea pig atria. In conscious SHR, 30 mg/kg p.o. AHR-16303B completely prevented the vasopressor responses to i.v. 5-HT, and decreased blood pressure (BP) by 24% 3 h after dosing.

  2. CCR2 antagonists.

    PubMed

    Struthers, Mary; Pasternak, Alexander

    2010-01-01

    Inhibition of CCR2 has been considered as a target for multiple therapeutic diseases including autoimmune disease, atherosclerosis, pain, and metabolic disease, based in part on the critical role this receptor plays on monocyte migration. Numerous companies have reported programs to identify CCR2 antagonists. Common challenges to the development of CCR2 agents have included poor activity at the rodent receptor and selectivity for both other chemokine receptors and ion channels. This review summarizes the rationale for targeting CCR2 in disease, the recent progress in the identification of potent and select CCR2 antagonists, and the current status of clinical trials for CCR2 agents.

  3. Induction of emesis in Suncus murinus by pyrogallol, a generator of free radicals.

    PubMed Central

    Torii, Y.; Saito, H.; Matsuki, N.

    1994-01-01

    1. We investigated whether or not pyrogallol, a generator of free radicals, is emetogenic in Suncus murinus, the house musk shrew. Pyrogallol (i.p.) caused dose-dependent emesis in suncus with an ED50 value of 77.3 mg kg-1. At a dose of 128 mg kg-1, all suncus vomited with mean latency of 18.8 +/- 5.2 min and the number of vomiting episodes was 8.6 +/- 2.9. 2. The prophylactic effects of N-(2-mercaptopropionyl)-glycine (MPG), an antioxidant, and tropisetron, a 5-hydroxytryptamine3 (5-HT3) receptor antagonist, were studied. Pyrogallol (128 mg kg-1, i.p.)-induced emesis was prevented by treatment with MPG (i.p.) or tropisetron (s.c.) with ID50 values of 149 mg kg-1 and 117 micrograms kg-1, respectively. 3. Pyrogallol-induced emesis was completely prevented by surgical abdominal vagotomy. 4. The present results indicate that pyrogallol-induced emesis is characteristically very similar to that caused by cisplatin and support the idea that generation of free radicals causes the release of peripheral 5-HT, which stimulates vagal afferent sensory nerves to cause emesis. PMID:8004387

  4. Opioid Antagonist Impedes Exposure.

    ERIC Educational Resources Information Center

    Merluzzi, Thomas V.; And Others

    1991-01-01

    Thirty spider-phobic adults underwent exposure to 17 phobic-related, graded performance tests. Fifteen subjects were assigned to naltrexone, an opioid antagonist, and 15 were assigned to placebo. Naltrexone had a significant effect on exposure, with naltrexone subjects taking significantly longer to complete first 10 steps of exposure and with…

  5. Opioid Antagonist Impedes Exposure.

    ERIC Educational Resources Information Center

    Merluzzi, Thomas V.; And Others

    1991-01-01

    Thirty spider-phobic adults underwent exposure to 17 phobic-related, graded performance tests. Fifteen subjects were assigned to naltrexone, an opioid antagonist, and 15 were assigned to placebo. Naltrexone had a significant effect on exposure, with naltrexone subjects taking significantly longer to complete first 10 steps of exposure and with…

  6. Advantages of an antagonist: bicuculline and other GABA antagonists

    PubMed Central

    Johnston, Graham AR

    2013-01-01

    The convulsant alkaloid bicuculline continues to be investigated more than 40 years after the first publication of its action as an antagonist of receptors for the inhibitory neurotransmitter GABA. This historical perspective highlights key aspects of the discovery of bicuculline as a GABA antagonist and the sustained interest in this and other GABA antagonists. The exciting advances in the molecular biology, pharmacology and physiology of GABA receptors provide a continuing stimulus for the discovery of new antagonists with increasing selectivity for the myriad of GABA receptor subclasses. Interesting GABA antagonists not structurally related to bicuculline include gabazine, salicylidene salicylhydrazide, RU5135 and 4-(3-biphenyl-5-(4-piperidyl)-3-isoxazole. Bicuculline became the benchmark antagonist for what became known as GABAA receptors, but not all ionotropic GABA receptors are susceptible to bicuculline. In addition, not all GABAA receptor antagonists are convulsants. Thus there are still surprises in store as the study of GABA receptors evolves. PMID:23425285

  7. Indications for Opioid Antagonists.

    PubMed

    Coppes, O J Michael; Sang, Christine N

    2017-06-01

    As opioids have become more common in clinical practice for the treatment of both acute and chronic pain, so too has the need for a deeper understanding of the clinical applications of opioid antagonists. The purpose of this review is to present both the longstanding and potential new indications for the use of drugs that block the effects of opioid receptors. There is a growing body of data demonstrating the modulation of pain by opioid antagonists. Additional clinical studies that show their direct antinociceptive effects and/or enhancement of the analgesic potency of opioid agonists are warranted. We briefly discuss the well-established role that these agents play in the reversal of life-threatening opioid toxicity and explore both existing and expanding clinical applications, including their apparent paradox that they may themselves be associated with analgesia.

  8. alpha2-Adrenoreceptor antagonists.

    PubMed

    Mayer, P; Imbert, T

    2001-06-01

    A review of the literature relating to the therapeutic potential of alpha2-adrenoceptor antagonists published between 1990 and 2000 is presented. Although extensively studied since the early 1970s in a wide spectrum of therapeutic applications, the distinction of alpha2-adrenoceptor subtypes and some emerging evidence concerning new applications in neurodegenerative disorders, such as Alzheimer's and Parkinson's diseases, obesity and schizophrenia, have refreshed an interest in this class of agents.

  9. Calcium antagonists and vasospasm.

    PubMed

    Meyer, F B

    1990-04-01

    A critical review of the clinical data supports the conclusion that nimodipine decreases the severity of neurologic deficits and improves outcome after subarachnoid hemorrhage. The mechanisms by which mortality and morbidity are reduced are still controversial. First, the frequency of vasospasm is not altered (Figs. 5 and 6). Second, the consistent reversal of vasospasm once present has not been demonstrated either angiographically or by noninvasive cerebral blood flow studies. These observations suggest that there is either modification of microcirculatory flow (i.e., dilation of pial conducting vessels or decreased platelet aggregation) or a direct neuronal protective effect. As suggested previously, support for either mechanism is not resolute, and further investigation is necessary. Currently, nimodipine has been the most thoroughly investigated calcium antagonist both from an experimental and clinical perspective. Oral administration has had few reported complications. Therefore, the benefit/risk ratio clearly supports the prophylactic use of this calcium antagonist in patients of all clinical grades after subarachnoid hemorrhage. Evidence also indicates that starting nimodipine after the onset of delayed ischemic deficits is of benefit. Finally, it can be predicted that in the future additional calcium antagonists with more selective vascular or neuronal effects will be developed for use in neurologic disorders.

  10. Possible involvement of 5-HT and 5-HT2 receptors in acceleration of gastrointestinal transit by escin Ib in mice.

    PubMed

    Matsuda, H; Li, Y; Yoshikawa, M

    2000-01-01

    We have reported previously that escin Ib accelerated gastrointestinal transit (GIT) in mice, and that its effect may be mediated by the release of endogenous prostaglandins (PGs) and nitric oxide (NO). In this study, the possible involvement of 5-HT and 5-HT receptors in the GIT acceleration of escin Ib was investigated in mice. The acceleration of GIT by escin Ib (25 or 50 mg/kg, p.o.) was attenuated by pretreatment with ritanserin (0.5-5 mg/kg, s.c., a 5-HT(2A/2C/2B) receptor antagonist), but not with MDL 72222 (1 and 5 mg/kg, s.c.) and metoclopramide (10 mg/kg, s.c.) (5-HT3 receptor antagonists) or tropisetron (1 and 10 mg/kg, s.c., a 5-HT(3/4) receptor antagonist). Furthermore, pretreatment with ketanserin (0.05-5 mg/kg, s.c.), haloperidol (1-5 mg/kg, s.c.) and spiperone (0.5-5 mg/kg, s.c.) (5-HT2A receptor antagonists), as well as a bolus of dl-p-chlorophenylalanine methyl ester (PCPA, 1000 mg/kg, p.o., 1, 6 or 24 h before administration of the sample) (an inhibitor of 5-HT synthesizing enzyme tryptophan hydroxylase) and reserpine (5 mg/kg, p.o.) (a 5-HT depletor), but not 6-hydroxydopamine (80 mg/kg, i.p., a dopamine depletor) or repeated PCPA (300 mg/kg x2, p.o., 72 and 48 h before administration of the sample), also attenuated the effects of escin Ib. It is postulated that escin Ib accelerates GIT, at least in part, by stimulating the synthesis of 5-HT to act through 5-HT2, possibly 5-HT2A receptors, which in turn causes the release of NO and PGs.

  11. Tetrahydroindolizinone NK1 antagonists.

    PubMed

    Bao, Jianming; Lu, Huagang; Morriello, Gregori J; Carlson, Emma J; Wheeldon, Alan; Chicchi, Gary G; Kurtz, Marc M; Tsao, Kwei-Lan C; Zheng, Song; Tong, Xinchun; Mills, Sander G; DeVita, Robert J

    2010-04-01

    A new class of potent NK(1) receptor antagonists with a tetrahydroindolizinone core has been identified. This series of compounds demonstrated improved functional activities as compared to previously identified 5,5-fused pyrrolidine lead structures. SAR at the 7-position of the tetrahydroindolizinone core is discussed in detail. A number of compounds displayed high NK(1) receptor occupancy at both 1 h and 24 h in a gerbil foot tapping model. Compound 40 has high NK(1) binding affinity, good selectivity for other NK receptors and promising in vivo properties. It also has clean P(450) inhibition and hPXR induction profiles. 2010 Elsevier Ltd. All rights reserved.

  12. Serotonergic Drugs: Agonists/Antagonists at Specific Serotonergic Subreceptors for the Treatment of Cognitive, Depressant and Psychotic Symptoms in Alzheimer's Disease.

    PubMed

    Werner, Felix-Martin; Covenas, Rafael

    2016-01-01

    Alzheimer's disease is a neurodegenerative disease showing alterations in classical neurotransmitters, above all in the hippocampus and prefrontal/temporal cortices. In this disease, acetylcholine shows hypoactivity, noradrenaline first shows hyperactivity, and during the course of the disease an increasing hypoactivity, glutamate shows hyperactivity and excitotoxicity and GABA shows hypoactivity. In post-mortem studies, serotonin levels and the number of specific serotonergic subreceptors, for example 5-HT1B receptors, decreased. We summarized the alterations of classical neurotransmitters in the brain regions involved in cognitive, depressive and psychotic symptoms in Alzheimer's disease. Starting from these neurotransmitter alterations, we describe neural networks including specific serotonergic subreceptors in the involved brain regions. In the hippocampus and prefrontal cortex, serotonin levels are associated with cognitive functions, whereas in the brainstem serotonin levels are related with affective symptoms. Psychotic symptoms which can occur in patients with Alzheimer's disease are associated with dopamine and serotonin hyperactivity in the mesolimbic system and hippocampus. The interaction between classical neurotransmitters and their specific subreceptors is shown in different brain areas. In clinical trials, the therapeutic effects of 5-HT4, 5-HT7 agonists and 5-HT3, 5-HT6 antagonists have been examined to improve cognitive symptoms in Alzheimer's disease. In these trials, 5-HT4 agonists and 5-HT4 antagonists showed a significant better effect in improving cognitive functions than placebo. The effect of such drugs on the formation of amyloid plaques is also examined. The appropriate use of antidepressant and antipsychotic drugs with an agonism or antagonism at specific serotonergic subreceptors is pointed out. Serotonin-selective antidepressant drugs significantly improve depressant symptoms and daily activities in Alzheimer patients and they are used

  13. QCM-4, a 5-HT₃ receptor antagonist ameliorates plasma HPA axis hyperactivity, leptin resistance and brain oxidative stress in depression and anxiety-like behavior in obese mice.

    PubMed

    Kurhe, Yeshwant; Mahesh, Radhakrishnan; Devadoss, Thangaraj

    2015-01-02

    Several preclinical studies have revealed antidepressant and anxiolytic-like effect of 5-HT3 receptor antagonists. In our earlier study, we have reported the antidepressive-like effect of 3-methoxy-N-p-tolylquinoxalin-2-carboxamide (QCM-4) in obese mice subjected to chronic stress. The present study deals with the biochemical mechanisms associated with depression co-morbid with obesity. Mice were fed with high fat diet (HFD) for 14 weeks, further subjected for treatment with QCM-4 (1 and 2mg/kg p.o.) and standard antidepressant escitalopram (ESC) (10mg/kg p.o.) for 28 days. Behavioral assays for depression such as sucrose preference test (SPT), forced swim test (FST) and for anxiety such as light and dark test (LDT) and hole board test (HBT) were performed in obese mice. Biochemical assessments including plasma leptin and corticosterone concentration followed by brain oxidative stress parameters malonaldehyde (MDA) and reduced glutathione (GSH) were performed. Results confirmed that QCM-4 exhibits antidepressive effect by increasing the sucrose consumption in SPT, reducing immobility time in FST and anxiolytic effect by increasing transitions and time in light chamber in LDT, increasing head dip and crossing score in HBT. Furthermore, QCM-4 attenuated the hypothalamic-pituitary-adrenal (HPA) axis hyperactivity by reducing the plasma corticosterone, reversing altered plasma leptin, restoring the imbalance of brain MDA and GSH concentration. In conclusion, QCM-4 showed antidepressive and anxiolytic effect by reversing the behavioral alterations that were supported by biochemical estimations in obese mice.

  14. Characterization of serotonergic mechanisms involved in the behavioural inhibition induced by 5-hydroxytryptophan in a modified light-dark test in mice.

    PubMed

    Artaiz, I; Zazpe, A; Del Río, J

    1998-03-01

    In a modified light-dark exploration test in mice, 5-hydroxytryptophan, at doses (25-50 mg/kg) that approximately doubled the 5-HT content in the cerebral cortex, reduced the time spent by mice in the white compartment, suggesting an anxiogenic effect. Depletion of brain 5-HT content with p-chlorophenylalanine (300 mg/kg/day for three consecutive days) resulted in an anxiolytic-like effect. Conversely, the 5-HT reuptake blocker fluoxetine reduced the time spent by mice in the white compartment. No significant interaction of either p-chlorophenylalanine or fluoxetine with 5-hydroxytryptophan was found. Several 5-HT agents, some of them with an intrinsic anxiolytic-like effect in this test, were studied in combination with 5-hydroxytryptophan. All of the drugs with a selective affinity at 5-HT1A receptors interacted significantly with 5-hydroxytryptophan. The suppressant effect of 5-hydroxytryptophan was antagonized or reversed by buspirone, a partial agonist at postsynaptic 5-HT1A receptors, and also by the "silent" 5-HT1A receptor antagonist WAY 100635, but not by the full agonist 8-OH-DPAT. The 5-HT2 receptor antagonist ritanserin partly counteracted the 5-hydroxytryptophan effect at the lower dose used. The 5-HT3 receptor antagonist ondansetron was able to prevent, at a low dose, the anxiogenic effect of 5-hydroxytryptophan; however, the 5-HT3 antagonists VA21B7 and granisetron as well as the 5-HT3/5-HT4 antagonist tropisetron and the selective 5-HT4 receptor antagonist RS 23597-190 were ineffective. The results appear to be consistent with the hypothesis that relates increased activity of the 5-HT systems to increased anxiety. Even though different 5-HT receptor subtypes may be involved in the anxiogenic effect of a high dose of 5-hydroxytryptophan, postsynaptic 5-HT1A receptors appear to play a prominent role. Administration of 5-hydroxytryptophan may consequently represent a valid approach to analyse further the role of 5-HT agents, in particular those acting

  15. Role of catecholamines and serotonin receptor subtypes in nefopam-induced antinociception.

    PubMed

    Girard, Philippe; Coppé, Marie-Claude; Verniers, Danielle; Pansart, Yannick; Gillardin, Jean-Marie

    2006-09-01

    The non-opiate analgesic nefopam has been shown to inhibit monoamines uptake, but little is known about receptor subtypes effectively involved in its analgesic effect. In vitro binding assays yielded the following measures of affinity (IC(50)): serotonergic 5-HT(2C) (1.4 microM), 5-HT(2A) (5.1 microM), 5-HT(3) (22.3 microM), 5-HT(1B) (41.7 microM), 5-HT(1A) (64.9 microM), adrenergic alpha(1) (15.0 microM) and dopaminergic D(1) (100 microM). Subcutaneous nefopam administration dose-dependently inhibited pain in acetic acid-induced writhing (1-30 mg kg(-1)) and formalin (1-10 mg kg(-1)) tests in the mouse. Pretreatments with adrenergic alpha(1) (prazosin) and alpha(2) (yohimbine), and serotonergic 5-HT(1B) (GR127935) receptor antagonists significantly increased the nefopam ED(50) in the writhing test. The serotonergic 5-HT(2C) (RS102221) and the dopaminergic D(2) (sulpiride) receptor antagonists inhibited nefopam antinociception in the formalin test. However, in both tests, nefopam analgesic activity was not modified by the following receptor antagonists: dopaminergic D(1) (SCH23390), serotonergic 5-HT(1A) (NAN-190, WAY100635), 5-HT(2A) (R96544, ketanserin), 5-HT(3) (tropisetron), and 5-HT(4) (SDZ205557). In conclusion, nefopam analgesic activity could be modulated by the adrenergic alpha(1) and alpha(2) receptors, the dopaminergic D(2) receptors, and the serotonergic 5-HT(1B) and 5-HT(2C) receptor subtypes.

  16. Small Molecule CXCR3 Antagonists.

    PubMed

    Andrews, Stephen P; Cox, Rhona J

    2016-04-14

    Chemokines and their receptors are known to play important roles in disease. More than 40 chemokine ligands and 20 chemokine receptors have been identified, but, to date, only two small molecule chemokine receptor antagonists have been approved by the FDA. The chemokine receptor CXCR3 was identified in 1996, and nearly 20 years later, new areas of CXCR3 disease biology continue to emerge. Several classes of small molecule CXCR3 antagonists have been developed, and two have shown efficacy in preclinical models of inflammatory disease. However, only one CXCR3 antagonist has been evaluated in clinical trials, and there remain many opportunities to further investigate known classes of CXCR3 antagonists and to identify new chemotypes. This Perspective reviews the known CXCR3 antagonists and considers future opportunities for the development of small molecules for clinical evaluation.

  17. The binding orientations of structurally-related ligands can differ; A cautionary note.

    PubMed

    Ruepp, Marc-David; Wei, Hao; Leuenberger, Michele; Lochner, Martin; Thompson, Andrew J

    2017-01-27

    Crystal structures can identify ligand-receptor interactions and assist the development of novel therapeutics, but experimental challenges sometimes necessitate the use of homologous proteins. Tropisetron is an orthosteric ligand at both 5-HT3 and α7 nACh receptors and its binding orientation has been determined in the structural homologue AChBP (pdbid: 2WNC). Co-crystallisation with a structurally-related ligand, granisetron, reveals an almost identical orientation (pdbid; 2YME). However, there is a >1000-fold difference in the affinity of tropisetron at 5-HT3 versus α7 nACh receptors, and α7 nACh receptors do not bind granisetron. These striking pharmacological differences prompt questions about which receptor the crystal structures most closely represent and whether the ligand orientations are correct. Here we probe the binding orientation of tropisetron and granisetron at 5-HT3 receptors by in silico modelling and docking, radioligand binding on cysteine-substituted 5-HT3 receptor mutants transiently expressed in HEK 293 cells, and synthetic modification of the ligands. For 15 of the 23 cysteine substitutions, the effects on tropisetron and granisetron were different. Structure-activity relationships on synthesised derivatives of both ligands were also consistent with different orientations, revealing that contrary to the crystallographic evidence from AChBP, the two ligands adopt different orientations in the 5-HT3 receptor binding site. Our results show that even quite structurally similar molecules can adopt different orientations in the same binding site, and that caution may be needed when using homologous proteins to predict ligand binding.

  18. A nonsteroidal glucocorticoid receptor antagonist.

    PubMed

    Miner, Jeffrey N; Tyree, Curtis; Hu, Junlian; Berger, Elaine; Marschke, Keith; Nakane, Masaki; Coghlan, Michael J; Clemm, Dave; Lane, Ben; Rosen, Jon

    2003-01-01

    Selective intracellular receptor antagonists are used clinically to ameliorate hormone-dependent disease states. Patients with Cushing's syndrome have high levels of the glucocorticoid, cortisol, and suffer significant consequences from this overexposure. High levels of this hormone are also implicated in exacerbating diabetes and the stress response. Selectively inhibiting this hormone may have clinical benefit in these disease states. To this end, we have identified the first selective, nonsteroidal glucocorticoid receptor (GR) antagonist. This compound is characterized by a tri-aryl methane core chemical structure. This GR-specific antagonist binds with nanomolar affinity to the GR and has no detectable binding affinity for the highly related receptors for mineralocorticoids, androgens, estrogens, and progestins. We demonstrate that this antagonist inhibits glucocorticoid-mediated transcriptional regulation. This compound binds competitively with steroids, likely occupying a similar site within the ligand-binding domain. Once bound, however, the compound fails to induce critical conformational changes in the receptor necessary for agonist activity.

  19. 5-HT1-like receptor-mediated contraction in the human internal mammary artery.

    PubMed

    Yildiz, O; Ciçek, S; Ay, I; Tatar, H; Tuncer, M

    1996-07-01

    We wished to characterize the 5-hydroxytryptamine (5-HT) receptors mediating vasoconstriction in the human internal mammary artery (IMA). Segments of the IMA obtained from patients undergoing coronary by-pass surgery were suspended in an organ bath and exposed to 5-HT and sumatriptan (SUM), a 5-HT1-like receptor agonist, in the presence and absence of potassium chloride (KCl) and angiotensin II. 5-HT induced concentration-dependent contractions in all quiescent and pre-contracted preparations. SUM induced small contractions in 70% of quiescent IMA rings, whereas it elicited marked and concentration-dependent contractions in all of the preparations given a moderate tone by a threshold concentration of KCl and angiotensin II. The efficacy of SUM was higher in precontracted arteries. Concentration-effect curves (CEC) of 5-HT and SUM were not affected by the 5-HT3-receptor antagonist tropisetron (1 microM). The nonselective antagonist, methiothepin (30 nM), shifted the CEC of SUM to the right. 5-HT2A-receptor antagonist, ketanserin (1 microM) inhibited responses to 5-HT, whereas it affected only the responses to the smaller concentrations of SUM. When methiothepin (30 nM) was applied in the presence of ketanserin (1 microM), a further inhibition in the responses to 5-HT was observed. These results suggest that 5-HT1-like receptors mediate the contractile action of SUM and contribute to that of 5-HT in IMA.

  20. Anti-Hu antibodies activate enteric and sensory neurons

    PubMed Central

    Li, Qin; Michel, Klaus; Annahazi, Anita; Demir, Ihsan E.; Ceyhan, Güralp O.; Zeller, Florian; Komorowski, Lars; Stöcker, Winfried; Beyak, Michael J.; Grundy, David; Farrugia, Gianrico; De Giorgio, Roberto; Schemann, Michael

    2016-01-01

    IgG of type 1 anti-neuronal nuclear antibody (ANNA-1, anti-Hu) specificity is a serological marker of paraneoplastic neurological autoimmunity (including enteric/autonomic) usually related to small-cell lung carcinoma. We show here that IgG isolated from such sera and also affinity-purified anti-HuD label enteric neurons and cause an immediate spike discharge in enteric and visceral sensory neurons. Both labelling and activation of enteric neurons was prevented by preincubation with the HuD antigen. Activation of enteric neurons was inhibited by the nicotinic receptor antagonists hexamethonium and dihydro-β-erythroidine and reduced by the P2X antagonist pyridoxal phosphate-6-azo (benzene-2,4-disulfonic acid (PPADS) but not by the 5-HT3 antagonist tropisetron or the N-type Ca-channel blocker ω-Conotoxin GVIA. Ca++ imaging experiments confirmed activation of enteric neurons but not enteric glia. These findings demonstrate a direct excitatory action of ANNA-1, in particular anti-HuD, on visceral sensory and enteric neurons, which involves nicotinic and P2X receptors. The results provide evidence for a novel link between nerve activation and symptom generation in patients with antibody-mediated gut dysfunction. PMID:27905561

  1. Potential serotonergic agents for the treatment of schizophrenia.

    PubMed

    Garay, Ricardo P; Bourin, Michel; de Paillette, Evelyne; Samalin, Ludovic; Hameg, Ahcène; Llorca, Pierre-Michel

    2016-01-01

    For the last 30 years, drugs targeting serotonin receptors (5-HTR) have been intensively investigated in schizophrenia. New drugs targeting 5-HTRs are under development in patients with schizophrenia. In this review, the authors describe the recent clinical trials for schizophrenia with selective serotonergic agents and provide an opinion on how the investigated drugs can help to fulfil current treatment needs. Clinical trials were found in US and EU clinical trial registries and in the medical literature. Relevant 5-HTR antagonists active in animal models of schizophrenia were also analysed. Antipsychotics reduce positive symptoms of schizophrenia (delusions, hallucinations and disordered thought), but have undesirable side effects. Moreover, satisfactory treatment of negative symptoms (apathy, poverty of speech, lack of interest in social interactions) and cognitive dysfunction is currently not available. The selective 5-HT2CR full agonist vabicaserin showed antipsychotic efficacy with fewer side effects than olanzapine. Adjunctive pimavanserin (a selective 5-HT2AR inverse agonist) facilitated antipsychotic dose and side-effect reductions. Selective 5-HT3R antagonists (ondansetron, tropisetron and granisetron) showed positive results on negative symptoms and/or cognitive impairments in phase II trials. Adjunctive ondansetron has now entered a phase III trial for such indications. Finally, 5-HTA5R and 5-HT7R antagonists have shown procognitive actions in animal models of schizophrenia. These novel serotonergic drugs seem promising for improving the current treatment of schizophrenia.

  2. Platelet-activating factor antagonists.

    PubMed

    Negro Alvarez, J M; Miralles López, J C; Ortiz Martínez, J L; Abellán Alemán, A; Rubio del Barrio, R

    1997-01-01

    Platelet-activating factor (PAF), identified as 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine, exhibits potent proinflammatory properties. PAF is produced by numerous cell types, including endothelial cells, neutrophils, monocytes, macrophages, basophils, eosinophils and mastocytes. Since the discovery and identification of the chemical structure of PAF, a large variety of specific PAF-receptor antagonists, both natural and synthetic compounds, have been described. Intensive research has been conducted and development programs set up by more 25 pharmaceutical companies world-wide, studying the therapeutic interest of more than 50 PAF-receptors antagonists in various pathophysiological conditions. Medline (1966-1996), Embase (Excerpta Medica; 1974-1996), and other biomedical and drug directory databases were searched to identify English-language articles (basic science, clinical trial research, and review articles) and abstracts of conference proceedings on PAF receptor antagonists and related terms. The most important PAF receptor antagonists are reviewed with their effectiveness in various experimental tests. Fundamentally, PAF antagonists may be divided in two groups: natural and synthetic compounds. Natural (Ginkgolides, Kadsurenone, Chantancin, Phomactin, Swietemohonin A, Prehispalone, THC-7-oic acid, Aglafoline, FR 900452, PCA 4248 and SCH 37370), and synthetic antagonists (CV-3988, CV-6209, SRI 63-072, SRI 63-441, UR-10324, UR-11353, E-5880, CL 184005, 6-Mono and Bis-aryl phosphate antagonists, TCV-309, Ro-74719, WEB 2086, Y 24180, BN 50726, BN 50727, BN 50730, BN 50739, Ro 24-4736, Ro 24-0238, RP 55778, RP 59227, RP 66681, YM 264, YM 461, SM 10661, SR 27417, UK 74505, BB 182, BB 823, BB 654, SDZ 64-412, SDZ 65-123, L 652731, L 659898, L 668750, L 671284, L680573, L 680574, CIS 19, ABT-299 and Pinusolide) have a great variability in their chemical structure that might have importance in their different pharmacological profile. The great majority of these

  3. Defining the efficacy of neurokinin-1 receptor antagonists in controlling chemotherapy-induced nausea and vomiting in different emetogenic settings-a meta-analysis.

    PubMed

    Jordan, Karin; Warr, David G; Hinke, Axel; Sun, Linda; Hesketh, Paul J

    2016-05-01

    This meta-analysis was performed to evaluate the efficacy of neurokinin-1 receptor antagonists (NK1RAs) for the prevention of chemotherapy-induced nausea and vomiting (CINV) across different categories of chemotherapeutic emetogenicity. A systematic review of MEDLINE (via PubMed) and OVID databases, plus major oncology conferences, identified randomized, controlled trials evaluating NK1RAs in combination with a 5-HT3 RA plus a glucocorticoid for management of CINV. Efficacy end points were no emesis, no nausea, and complete response (CR) rates. Data were analyzed using a random effects model. Twenty-three trials (N = 11,814) were identified. Based on absolute differences (AD) for no emesis (21 %), no nausea (8 %), CR (16 %), and odd ratios (OR) of 2.62, 1.43, and 2.16, respectively, NK1RA regimens provided better CINV protection versus control groups (all p < 0.00001) in patients receiving cisplatin-based highly emetogenic chemotherapy (HEC). In patients receiving anthracycline/cyclophosphamide (AC)-based HEC, respective ADs and ORs were 14, 4, and 11 % and 1.97 (p < 0.0001), 1.17 (p = 0.04), and 1.62 (p < 0.00001). In patients receiving moderately emetogenic chemotherapy (3 trials), no statistically significant benefit of NK1RAs was found; however, positive trends were detected for CR and no emesis. NK1RAs were effective for CINV prevention in a small number of studies using high-dose chemotherapy as conditioning prior to stem cell transplant and cisplatin-based multiple-day chemotherapy (MDC). This meta-analysis demonstrated the efficacy of NK1RA in preventing vomiting in patients receiving HEC (including AC), with smaller effects on prevention of nausea. Efficacy is also seen with high-dose chemotherapy and cisplatin-based MDC.

  4. Antidepressant & anxiolytic activities of N-(pyridin-3-yl) quinoxalin-2-carboxamide: A novel serotonin type 3 receptor antagonist in behavioural animal models

    PubMed Central

    Pandey, Dilip Kumar; Devadoss, Thangraj; Modak, Neha; Mahesh, Radhakrishnan

    2016-01-01

    Background & objectives: Alteration in the serotonin leads to the psychological illness, such as depression, anxiety, schizophrenia, eating disorders, obsessive-compulsive disorder, panic disorders and migraines. The objective of the current study was to investigate the antidepressant and anxiolytic activities of N-(pyridin-3-yl) quinoxalin-2-carboxamide (QCF-21), a novel 5-HT3 receptor antagonist in preclinical models of depression and anxiety. Methods: Antidepressant activity was evaluated in preliminary tests such as forced swim and tail suspension tests (FST & TST). Anti-anxiety effect of QCF-21 was investigated by employing elevated plus maze (EPM), light/dark and hole board tests. Olfactory bulbectomy (OBX) in rats was used as chronic model of depression. Mechanistic test of QCF-21 was evaluated by reserpine-induced hypothermia and 5-hydroxytryptophan (5-HTP)-induced head-twitch response. Results: The dose-response study revealed an initial antidepressant-like effect of QCF-21(0.25-1 mg/kg, i.p.) in the FST and TST and anxiolytic-like effect in EPM, light and dark and hole board tests. QCF-21 potentiated the 5-HTP-induced head-twitches response in mice and reversed reserpine-induced hypothermia in rats. QCF-21 significantly reversed the behavioural anomalies post-OBX in rats. Interpretation & conclusions: The present findings indicate the potential antidepressant-like and anxiolytic-like effects of QCF-21 at low doses in rodent behavioural models of depression and anxiety. Further studies need to be done to understand the underlying mechanism. PMID:28256473

  5. Analysis of free ACh and 5-HT in milk from four different species and their bioactivity on 5-HT(3) and nACh receptors.

    PubMed

    Gallegos-Perez, Jose-Luis; Limon, Agenor; Reyes-Ruiz, Jorge M; Alshanqeeti, Ali S; Aljohi, Mohammad A; Miledi, Ricardo

    2014-07-25

    Milk is one of the most beneficial aliments and is highly recommended in normal conditions; however, in certain disorders, like irritable bowel syndrome, cow milk and dairy products worsen the gastric symptoms and their use is not recommended. Among the most recognized milk-induced gatrointestinal symptoms are abdominal pain, nausea and vomiting, which are processes controlled by cholinergic and serotonergic transmission. Whether the presence of bioavailable ACh and 5-HT in milk may contribute to normal peristalsis, or to the developing of these symptoms, is not known. In this work we attempt to determine whether the content of free ACh and 5-HT is of physiological significance in milk from four different species: cow (bovine), goat, camel and human. Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was used to identify and quantify free ACh and 5-HT in milk, and activation of the serotonergic and cholinergic ionotropic receptors was investigated using electrophysiological experiments. Our principal hypothesis was that milk from these four species had sufficient free ACh and 5-HT to activate their correspondent receptors expressed in a heterologous system. Our results showed a more complex picture, in which free ACh and 5-HT and their ability to activate cholinergic and serotonergic receptors are not correlated. This work is a first step to elucidate whether 5-HT and ACh, at the concentrations present in the milk, can be associated to a direct function in the GI.

  6. Opioid antagonists for smoking cessation

    PubMed Central

    David, Sean P; Lancaster, Tim; Stead, Lindsay F; Evins, A. Eden; Prochaska, Judith J

    2014-01-01

    Background The reinforcing properties of nicotine may be mediated through release of various neurotransmitters both centrally and systemically. People who smoke report positive effects such as pleasure, arousal, and relaxation as well as relief of negative affect, tension, and anxiety. Opioid (narcotic) antagonists are of particular interest to investigators as potential agents to attenuate the rewarding effects of cigarette smoking. Objectives To evaluate the efficacy of opioid antagonists in promoting long-term smoking cessation. The drugs include naloxone and the longer-acting opioid antagonist naltrexone. Search methods We searched the Cochrane Tobacco Addiction Group Specialised Register for trials of naloxone, naltrexone and other opioid antagonists and conducted an additional search of MEDLINE using ’Narcotic antagonists’ and smoking terms in April 2013. We also contacted investigators, when possible, for information on unpublished studies. Selection criteria We considered randomised controlled trials comparing opioid antagonists to placebo or an alternative therapeutic control for smoking cessation. We included in the meta-analysis only those trials which reported data on abstinence for a minimum of six months. We also reviewed, for descriptive purposes, results from short-term laboratory-based studies of opioid antagonists designed to evaluate psycho-biological mediating variables associated with nicotine dependence. Data collection and analysis We extracted data in duplicate on the study population, the nature of the drug therapy, the outcome measures, method of randomisation, and completeness of follow-up. The main outcome measure was abstinence from smoking after at least six months follow-up in patients smoking at baseline. Abstinence at end of treatment was a secondary outcome. We extracted cotinine- or carbon monoxide-verified abstinence where available. Where appropriate, we performed meta-analysis, pooling risk ratios using a Mantel

  7. Mineralcorticoid antagonists in heart failure.

    PubMed

    D'Elia, Emilia; Krum, Henry

    2014-10-01

    Mineralocorticoid receptor antagonists (MRAs) have become mandated therapy in patients with reduced ejection fraction (systolic) heart failure (HF) across all symptom classes. These agents should also be prescribed in the early post-myocardial infarction setting in those with reduced ejection fraction and either HF symptoms or diabetes. This article explores the pathophysiological role of aldosterone, an endogenous ligand for the mineralcorticoid receptor (MR), and summarizes the clinical data supporting guideline recommendations for these agents in systolic HF. The use of MRAs in novel areas beyond systolic HF ejection is also explored. Finally, the current status of newer agents will be examined.

  8. NK-1 Antagonists and Itch.

    PubMed

    Ständer, Sonja; Luger, Thomas A

    2015-01-01

    Substance P (SP) is an important mediator of pro-inflammatory mechanisms in the skin. It targets multiple cells such as keratinocytes, mast cells, and fibroblasts which are involved in the cutaneous generation of pruritus. This suggests that SP is an interesting target for therapy. In fact, in recent case reports and case series, SP antagonists demonstrated a significant antipruritic effect in acute and chronic pruritus such as drug-induced pruritus, paraneoplastic pruritus, prurigo nodularis, cutaneous T-cell lymphoma, and brachioradial pruritus.

  9. Synthesis and structure-activity relationships of a new model of arylpiperazines. 5. Study of the physicochemical influence of the pharmacophore on 5-HT(1a)/alpha(1)-adrenergic receptor affinity: synthesis of a new derivative with mixed 5-HT(1a)/d(2) antagonist properties.

    PubMed

    López-Rodríguez, M L; Morcillo, M J; Fernández, E; Porras, E; Orensanz, L; Beneytez, M E; Manzanares, J; Fuentes, J A

    2001-01-18

    In this paper we have designed and synthesized a test series of 32 amide arylpiperazine derivatives VI in order to gain insight into the physicochemical influence of the pharmacophores of 5-HT(1A) and alpha(1)-adrenergic receptors. The training set was designed applying a fractional factorial design using six physicochemical descriptors. The amide moiety is a bicyclohydantoin or a diketopiperazine (X = -(CH(2))(3)-, -(CH(2))(4)-; m = 0, 1), the spacer length is 3 or 4 methylene units, which are the optimum values for both receptors, and the aromatic substituent R occupies the ortho- or meta-position and has been selected from a database of 387 substituents using the EDISFAR program. The 5-HT(1A) and alpha(1)-adrenergic receptor binding affinities of synthesized compounds VI (1-32) have been determined. This data set has been used to derive classical quantitative structure-activity relationships (QSAR) and neural networks models for both receptors (following paper). A comparison of these models gives information for the design of the new ligand EF-7412 (46) (5-HT(1A): K(i) = 27 nM; alpha(1): K(i) > 1000 nM). This derivative displays affinity for the dopamine D(2) receptor (K(i) = 22 nM) and is selective versus all other receptors examined (5-HT(2A), 5-HT(3), 5-HT(4) and Bz; K(i) > 1000 nM). EF-7412 (46) acts as an antagonist in vivo in pre- and postsynaptic 5-HT(1A) receptor sites and as an antagonist in the dopamine D(2) receptor. Thus, EF-7412 (46) is a derivative with mixed 5-HT(1A)/D(2) antagonist properties and this derivative could be useful as a pharmacological tool.

  10. Synthetic peptide antagonists of glucagon.

    PubMed Central

    Unson, C G; Andreu, D; Gurzenda, E M; Merrifield, R B

    1987-01-01

    Several glucagon analogs were synthesized in an effort to find derivatives that would bind with high affinity to the glucagon receptor of rat liver membranes but would not activate membrane-bound adenylate cyclase and, therefore, would serve as antagonists of the hormone. Measurements on a series of glucagon/secretin hybrids indicated that replacement of Asp9 in glucagon by Glu9, found in secretin, was the important sequence difference in the N terminus of the two hormones. Further deletion of His1 and introduction of a C-terminal amide resulted in des-His1-[Glu9]glucagon amide, which had a 40% binding affinity relative to that of native glucagon but caused no detectable adenylate cyclase activation in the rat liver membrane. This antagonist completely inhibited the effect of a concentration of glucagon that alone gave a full agonist response. It had an inhibition index of 12. The pA2 was 7.2. An attempt was made to relate conformation with receptor binding. The peptides were synthesized by solid-phase methods and purified to homogeneity by reverse-phase high-performance liquid chromatography on C18-silica columns. PMID:3035568

  11. Vitamin K antagonists: beyond bleeding.

    PubMed

    Krüger, Thilo; Floege, Jürgen

    2014-01-01

    Warfarin is the most widely used oral anticoagulant in clinical use today. Indications range from prosthetic valve replacement to recurrent thromboembolic events due to antiphospholipid syndrome. In hemodialysis (HD) patients, warfarin use is even more frequent than in the nonrenal population due to increased cardiovascular comorbidities. The use of warfarin in dialysis patients with atrial fibrillation requires particular caution because side effects may outweigh the assumed benefit of reduced stroke rates. Besides increased bleeding risk, coumarins exert side effects which are not in the focus of clinical routine, yet they deserve special consideration in dialysis patients and should influence the decision of whether or not to prescribe vitamin K antagonists in cases lacking clear guidelines. Issues to be taken into consideration in HD patients are the induction or acceleration of cardiovascular calcifications, a 10-fold increased risk of calciphylaxis and problems related to maintaining a target INR range. New anticoagulants like direct thrombin inhibitors are promising but have not yet been approved for ESRD patients. Here, we summarize the nontraditional side effects of coumarins and give recommendations about the use of vitamin K antagonists in ESRD patients.

  12. Cholinergic antagonists in a solitary wasp venom.

    PubMed

    Piek, T; Mantel, P

    1986-01-01

    The venom of the solitary wasp Philanthus triangulum contains a cholinergic antagonist of the nicotinic receptor of the rectus abdominis muscle of the frog, Xenopus laevis. The venom of African P. triangulum contains two different cholinergic factors, a competitive and a non-competitive antagonist. The venom of the European P. triangulum may not contain a competitive antagonist of the nicotinic receptor of X. laevis, but only a very strong non-competitive antagonist. The possible non-synonymity of both groups of P. triangulum is discussed.

  13. Existence of Brain 5-HT1A-5-HT2A Isoreceptor Complexes with Antagonistic Allosteric Receptor-Receptor Interactions Regulating 5-HT1A Receptor Recognition.

    PubMed

    Borroto-Escuela, Dasiel O; Li, Xiang; Tarakanov, Alexander O; Savelli, David; Narváez, Manuel; Shumilov, Kirill; Andrade-Talavera, Yuniesky; Jimenez-Beristain, Antonio; Pomierny, Bartosz; Díaz-Cabiale, Zaida; Cuppini, Riccardo; Ambrogini, Patrizia; Lindskog, Maria; Fuxe, Kjell

    2017-08-31

    Studies on serotonin-selective reuptake inhibitors have established that disturbances in the ascending 5-HT neuron systems and their 5-HT receptor subtypes and collateral networks to the forebrain contribute to the etiology of major depression and are targets for treatment. The therapeutic action of serotonin-selective reuptake inhibitors is of proven effectiveness, but the mechanisms underlying their effect are still unclear. There are many 5-HT subtypes involved; some need to be blocked (e.g., 5-HT2A, 5-HT3, and 5-HT7), whereas others need to be activated (e.g., postjunctional 5-HT1A and 5-HT4). These state-of-the-art developments are in line with the hypothesis that the development of major depression can involve an imbalance of the activity between different types of 5-HT isoreceptors. In the current study, using in situ proximity ligation assay (PLA), we report evidence for the existence of brain 5-HT1A-5-HT2A isoreceptor complexes validated in cellular models with bioluminescence resonance energy transfer (BRET(2)) assay. A high density of PLA-positive clusters visualizing 5-HT1A-5-HT2A isoreceptor complexes was demonstrated in the pyramidal cell layer of the CA1-CA3 regions of the dorsal hippocampus. A marked reduction in the density of PLA-positive clusters was observed in the CA1 and CA2 regions 24 h after a forced swim test session, indicating the dynamics of this 5-HT isoreceptor complex. Using a bioinformatic approach, previous work indicates that receptors forming heterodimers demonstrate triplet amino acid homologies. The receptor interface of the 5-HT1A-5-HT2A isoreceptor dimer was shown to contain the LLG and QNA protriplets in the transmembrane and intracellular domain, respectively. The 5-HT2A agonist TCB2 markedly reduced the affinity of the 5-HT1A agonist ipsapirone for the 5-HT1A agonist binding sites in the frontal lobe using the 5-HT1A radioligand binding assay. This action was blocked by the 5-HT2A antagonist ketanserin. It is proposed that

  14. A new alcohol antagonist: Phaclofen

    SciTech Connect

    Allan, A.M. ); Harris, R.A. )

    1989-01-01

    The ability of the GABA{sub B} receptor antagonist, phaclofen to alter behavioral effects of ethanol was evaluated by loss of righting reflex (sleep time), motor incoordination (bar holding), spontaneous locomotion (open field activity) and hypothermia. Pretreatment with phaclofen significantly decreased the effects of ethanol on motor incoordination, locomotor activity and hypothermia. However, phaclofen had no effect on either pentobarbital- or diazepam-induced motor incoordination. Phaclofen slightly increased the ED{sub 50} for loss of the righting reflex but did not alter either the duration of reflex loss produced by ethanol or blood ethanol levels at awakening. Our results suggest phaclofen is rapidly inactivated resulting in difficulty in observing antagonism of long duration ethanol effects. These findings suggest that the GABA{sub B} system may play a role in mediating several important actions of ethanol.

  15. Long-acting muscarinic antagonists.

    PubMed

    Melani, Andrea S

    2015-01-01

    Chronic obstructive pulmonary disease (COPD) is a major cause of death and disability worldwide. Inhaled bronchodilators are the mainstay of COPD pharmacological treatment. Long-acting muscarinic antagonists (LAMAs) are a major class of inhaled bronchodilators. Some LAMA/device systems with different characteristics and dosing schedules are currently approved for maintenance therapy of COPD and a range of other products are being developed. They improve lung function and patient-reported outcomes and reduce acute bronchial exacerbations with good safety. LAMAs are used either alone or associated with long-acting β₂-agonists, eventually in fixed dose combinations. Long-acting β₂-agonist/LAMA combinations assure additional benefits over the individual components alone. The reader will obtain a view of the safety and efficacy of the different LAMA/device systems in COPD patients.

  16. Client Perceptions of Two Antagonist Programs.

    ERIC Educational Resources Information Center

    Capone, Thomas A.; And Others

    1980-01-01

    Reports results of a questionnaire administered to participants in an antagonist drug outpatient clinic and an antagonist drug work-release program to obtain awareness of acceptance of the program participants. Naltrexone patients recommended an alternative method of administering the drug and changing the money system to award deserving inmates…

  17. Antidepressant-like activity of 2-(4-phenylpiperazin-1-yl)-1, 8-naphthyridine-3-carboxylic acid (7a), a 5-HT₃ receptor antagonist in behaviour based rodent models: evidence for the involvement of serotonergic system.

    PubMed

    Gautam, Baldev Kumar; Jindal, Ankur; Dhar, Arghya Kusum; Mahesh, Radhakrishnan

    2013-08-01

    The present study was designed to investigate the putative antidepressant-like activity of 7a, a 5-HT₃ receptor antagonist, (although indirect evidence of 5-HT3 antagonism) with an optimal log P (3.35) and pA₂ value (7.6) greater than ondansetron (pA₂--6.6) using behavioural tests battery of depression. Acute treatment of 7a (0.5-2 mg/kg, i.p.) in mice produced antidepressant-like effects in forced swim test (FST) and tail suspension test (TST) without affecting the baseline locomotion in actophotometer test in mice. Moreover, the combination of a sub-effective dose of 7a (0.25 mg/kg, i.p.) and fluoxetine (5 mg/kg, i.p.) produced an anti-immobility effect in mouse FST. Pretreatment of mice with p-chlorophenylalanine methyl ester (PCPA; 100 mg/kg, i.p., an inhibitor of serotonin (5-HT) synthesis, for 4 consecutive days) and 1-(m-Chlorophenyl)-biguanide (mCPBG, 10 mg/kg, i.p., a 5-HT₃ receptor agonist) prevented the anti-immobility effects of 7a (2 mg/kg, i.p.) in the mouse FST. In addition, 7a (0.5-2 mg/kg, i.p.) treatment also potentiated the 5-hydroxytryptophan (5-HTP) and pargyline induced head twitch response in mice. Furthermore, sub-chronic treatment (14 days) with 7a (0.5-2 mg/kg, i.p.) and paroxetine (10 mg/kg, i.p.) significantly attenuated the behavioural anomalies induced by bilateral olfactory bulbectomy in rats in a modified open field paradigm. These results suggest that the antidepressant-like action of 7a may be mediated by an interaction with the serotonergic system and this molecule should be further investigated as an alternative therapeutic approach for the treatment of depression.

  18. Antagonistic coevolution accelerates molecular evolution

    PubMed Central

    Paterson, Steve; Vogwill, Tom; Buckling, Angus; Benmayor, Rebecca; Spiers, Andrew J.; Thomson, Nicholas R.; Quail, Mike; Smith, Frances; Walker, Danielle; Libberton, Ben; Fenton, Andrew; Hall, Neil; Brockhurst, Michael A.

    2013-01-01

    The Red Queen hypothesis proposes that coevolution of interacting species (such as hosts and parasites) should drive molecular evolution through continual natural selection for adaptation and counter-adaptation1–3. Although the divergence observed at some host-resistance4–6 and parasite-infectivity7–9 genes is consistent with this, the long time periods typically required to study coevolution have so far prevented any direct empirical test. Here we show, using experimental populations of the bacterium Pseudomonas fluorescens SBW25 and its viral parasite, phage Φ2 (refs 10, 11), that the rate of molecular evolution in the phage was far higher when both bacterium and phage coevolved with each other than when phage evolved against a constant host genotype. Coevolution also resulted in far greater genetic divergence between replicate populations, which was correlated with the range of hosts that coevolved phage were able to infect. Consistent with this, the most rapidly evolving phage genes under coevolution were those involved in host infection. These results demonstrate, at both the genomic and phenotypic level, that antagonistic coevolution is a cause of rapid and divergent evolution, and is likely to be a major driver of evolutionary change within species. PMID:20182425

  19. Antianginal Actions of Beta-Adrenoceptor Antagonists

    PubMed Central

    2007-01-01

    Angina pectoris is usually the first clinical sign of underlying myocardial ischemia, which results from an imbalance between oxygen supply and oxygen demand in the heart. This report describes the pharmacology of β-adrenoceptor antagonists as it relates to the treatment of angina. The β-adrenoceptor antagonists are widely used in long-term maintenance therapy to prevent acute ischemic episodes in patients with chronic stable angina. Beta-adrenoceptor antagonists competitively inhibit the binding of endogenous catecholamines to β1-adrenoceptors in the heart. Their anti-ischemic effects are due primarily to a reduction in myocardial oxygen demand. By decreasing heart rate, myocardial contractility and afterload, β-adrenoceptor antagonists reduce myocardial workload and oxygen consumption at rest as well as during periods of exertion or stress. Predictable adverse effects include bradycardia and cardiac depression, both of which are a direct result of the blockade of cardiac β1-adrenoceptors, but adverse effects related to the central nervous system (eg, lethargy, sleep disturbances, and depression) may also be bothersome to some patients. Beta-adrenoceptor antagonists must be used cautiously in patients with diabetes mellitus, peripheral vascular disease, heart failure, and asthma or other obstructive airway diseases. Beta-adrenoceptor antagonists may be used in combination with nitrates or calcium channel blockers, which takes advantage of the diverse mechanisms of action of drugs from each pharmacologic category. Moreover, concurrent use of β-adrenoceptor antagonists may alleviate the reflex tachycardia that sometimes occurs with other antianginal agents. PMID:17998992

  20. Acute Radiation Sickness Amelioration Analysis

    DTIC Science & Technology

    1994-05-01

    it was found that metoclopramide , the most efficacious of the existing anti-emetic drugs, also acted as an antagonist at 5-HT3 receptors. Unlike the...newer, more specific 5-HT3 antagonists listed above, however, metoclopramide also acts as an antagonist at dopamine type-2 receptors. It is known...that the dopamine-blocking actions of metoclopramide are responsible for the undesirable side effects produced by this drug and a number of other less

  1. Ago-antagonist theory in Darwinian evolution.

    PubMed

    Bazzani, Armando; Freguglia, Paolo

    2013-01-01

    In this paper we discuss a proposal on the essential structural aspects of Darwinian Evolution Theory. Using this point of view we apply a mathematical ago-antagonist theory inspired by Y. Cherruault's (1998) ideas, which we have extended. In the ago-antagonist model, the phenotype characters measure the individual propensity to perform an innovative x(t) (agonist) or conservative y(t) (antagonist) action with respect to mutation and to speciation process. We have mathematically introduced the conflict concept and we present a model that takes into account the environmental effects by means of a stochastic multiplicative process. We shortly discuss the properties of the related stochastic differential equations.

  2. Antagonists of the kappa opioid receptor.

    PubMed

    Urbano, Mariangela; Guerrero, Miguel; Rosen, Hugh; Roberts, Edward

    2014-05-01

    The research community has increasingly focused on the development of OPRK antagonists as pharmacotherapies for the treatment of depression, anxiety, addictive disorders and other psychiatric conditions produced or exacerbated by stress. Short-acting OPRK antagonists have been recently developed as a potential improvement over long-acting prototypic ligands including nor-BNI and JDTic. Remarkably the short-acting LY2456302 is undergoing phase II clinical trials for the augmentation of the antidepressant therapy in treatment-resistant depression. This Letter reviews relevant chemical and pharmacological advances in the identification and development of OPRK antagonists.

  3. Plant Evolution: Evolving Antagonistic Gene Regulatory Networks.

    PubMed

    Cooper, Endymion D

    2016-06-20

    Developing a structurally complex phenotype requires a complex regulatory network. A new study shows how gene duplication provides a potential source of antagonistic interactions, an important component of gene regulatory networks.

  4. The Evolution of Sexually Antagonistic Phenotypes

    PubMed Central

    Perry, Jennifer C.; Rowe, Locke

    2015-01-01

    Sexual conflict occurs whenever there is sexually antagonistic selection on shared traits. When shared traits result from interactions (e.g., mating rate) and have a different genetic basis in each sex (i.e., interlocus conflict), then sex-specific traits that shift the value of these interaction traits toward the sex-specific optimum will be favored. Male traits can be favored that increase the fitness of their male bearers, but decrease the fitness of interacting females. Likewise, female traits that reduce the costs of interacting with harmful males may simultaneously impose costs on males. If the evolution of these antagonistic traits changes the nature of selection acting on the opposite sex, interesting coevolutionary dynamics will result. Here we examine three current issues in the study of sexually antagonistic interactions: the female side of sexual conflict, the ecological context of sexual conflict, and the strength of evidence for sexually antagonistic coevolution. PMID:26032715

  5. Emerging cardiovascular indications of mineralocorticoid receptor antagonists.

    PubMed

    Parviz, Yasir; Iqbal, Javaid; Pitt, Bertram; Adlam, David; Al-Mohammad, Abdallah; Zannad, Faiez

    2015-04-01

    Mineralocorticoid receptor (MR) antagonism is a well-established treatment modality for patients with hypertension, heart failure, and left ventricular systolic dysfunction (LVSD) post-myocardial infarction (MI). There are emerging data showing potential benefits of MR antagonists in other cardiovascular conditions. Studies have shown association between MR activation and the development of myocardial fibrosis, coronary artery disease, metabolic syndrome, and cerebrovascular diseases. This review examines the preclinical and clinical data of MR antagonists for novel indications including heart failure with preserved ejection fraction (HFPEF), pulmonary arterial hypertension (PAH), arrhythmia, sudden cardiac death, valvular heart disease, metabolic syndrome, renal disease, and stroke. MR antagonists are not licensed for these conditions yet; however, emerging data suggest that indication for MR antagonists are likely to broaden; further studies are warranted.

  6. Macrophages: micromanagers of antagonistic signaling nanoclusters.

    PubMed

    Eggeling, Christian; Davis, Simon J

    2017-04-03

    How cells integrate antagonistic receptor signaling events is enigmatic. Using superresolution optical microscopy, Lopes et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201608094) demonstrate the nanometer-scale molecular reorganization of antagonistic signaling receptors in macrophages, after engagement by the receptors of activating and inhibitory ligands. They propose that large-scale rearrangements of this type underpin decision-making by these cells.

  7. Pharmacological profile of the 5-HT-induced inhibition of cardioaccelerator sympathetic outflow in pithed rats: correlation with 5-HT1 and putative 5-ht5A/5B receptors

    PubMed Central

    Sánchez-López, Araceli; Centurión, David; Vázquez, Erika; Arulmani, Udayasankar; Saxena, Pramod R; Villalón, Carlos M

    2003-01-01

    Continuous infusions of 5-hydroxytryptamine (5-HT) inhibit the tachycardiac responses to preganglionic (C7-T1) sympathetic stimulation in pithed rats pretreated with desipramine. The present study identified the pharmacological profile of this inhibitory action of 5-HT. The inhibition induced by intravenous (i.v.) continuous infusions of 5-HT (5.6 μg kg−1 min−1) on sympathetically induced tachycardiac responses remained unaltered after i.v. treatment with saline or the antagonists GR 127935 (5-HT1B/1D), the combination of WAY 100635 (5-HT1A) plus GR 127935, ritanserin (5-HT2), tropisetron (5-HT3/4), LY215840 (5-HT7) or a cocktail of antagonists/inhibitors consisting of yohimbine (α2), prazosin (α1), ritanserin, GR 127935, WAY 100635 and indomethacin (cyclooxygenase), but was abolished by methiothepin (5-HT1/2/6/7 and recombinant 5-ht5A/5B). These drugs, used in doses high enough to block their respective receptors/mechanisms, did not modify the sympathetically induced tachycardiac responses per se. I.v. continuous infusions of the agonists 5-carboxamidotryptamine (5-CT; 5-HT1/7 and recombinant 5-ht5A/5B), CP 93,129 (r5-HT1B), sumatriptan (5-HT1B/1D), PNU-142633 (5-HT1D) and ergotamine (5-HT1B/1D and recombinant 5-ht5A/5B) mimicked the above sympatho-inhibition to 5-HT. In contrast, the agonists indorenate (5-HT1A) and LY344864 (5-ht1F) were inactive. Interestingly, 5-CT-induced cardiac sympatho-inhibition was abolished by methiothepin, the cocktail of antagonists/inhibitors, GR 127935 or the combination of SB224289 (5-HT1B) plus BRL15572 (5-HT1D), but remained unchanged when SB224289 or BRL15572 were given separately. Therefore, 5-HT-induced cardiac sympatho-inhibition, being unrelated to 5-HT2, 5-HT3, 5-HT4, 5-ht6, 5-HT7 receptors, α1/2-adrenoceptor or prostaglandin synthesis, seems to be primarily mediated by (i) 5-HT1 (probably 5-HT1B/1D) receptors and (ii) a novel mechanism antagonized by methiothepin that, most likely, involves putative 5-ht5A/5B

  8. Effects of 5-HT receptor agonists on depolarization-induced [3H]-noradrenaline release in rabbit hippocampus and human neocortex.

    PubMed Central

    Allgaier, C.; Warnke, P.; Stangl, A. P.; Feuerstein, T. J.

    1995-01-01

    1. The present study attempted to determine whether noradrenaline (NA) release in rabbit hippocampus and human neocortex is modulated by presynaptic 5-hydroxytryptamine (5-HT) receptors. 2. Slices of rabbit hippocampus and human neocortex, loaded with [3H]-noradrenaline ([3H]-NA) were superfused and the effects of 5-hydroxytryptamine (5-HT) receptor ligands on electrically evoked [3H]-NA release were investigated. 3. In rabbit hippocampus, 5-HT, 5-carboxamidotryptamine (5-CT; 32 microM) and 2-CH3-5-HT (32 microM) increased [3H]-NA release elicited with 360 pulses/3 Hz. Facilitation of transmitter release was not influenced by the 5-HT3 receptor antagonist, tropisetron but was prevented by the alpha 2-adrenoceptor antagonist, rauwolscine. When autoinhibition was avoided by stimulating the tissue with 4 pulses/100 Hz (pseudo-one pulse-(POP) stimulation), 2-CH3-5-HT decreased evoked transmitter release, whereas 5-HT and 5-CT had no effect. Inhibition caused by 2-CH3-5-HT was not affected by tropisetron but counteracted by the alpha 2-adrenoceptor ligands, clonidine and rauwolscine. Inhibition caused by clonidine was diminished in the presence of 5-CT or 2-CH3-5-HT. 4. In human neocortex, [3H]-NA release elicited with 360 pulses/3 Hz was increased by 10 microM 5-HT and 32 microM 5-CT, whereas 2-CH3-5-HT was ineffective. [3H]-NA release evoked with a modified POP stimulation (2 bursts of 4 pulses/100 Hz, 3.5 min apart) was not affected by 2-CH3-5-HT or 5-CT. 5. The present results indicate that 5-HT, 2-CH3-5-HT and 5-CT can act on presynaptic alpha 2-autoreceptors as partial agonists (2-CH3-5-HT; in rabbit hippocampal tissue) or antagonists (5-HT and 5-CT; in tissue of rabbit hippocampus and human neocortex). Furthermore the existence of autoinhibition dictates whether these drugs cause facilitation of release, inhibition or have no effect. PMID:8528558

  9. Calcium antagonists and atherosclerosis protection in hypertension.

    PubMed

    Hernández, Rafael Hernández; Armas-Hernández, María José; Velasco, Manuel; Israili, Zafar H; Armas-Padilla, María Cristina

    2003-01-01

    Calcium antagonists are effective in hypertensive patients of all ethnic groups, irrespective of age, dietary salt intake, salt-sensitivity status or plasma renin activity profile. Some prospective studies show that the calcium antagonists, nifedipine GITS and nitrendipine, reduce cardiovascular morbidity and mortality at least to the same extent as the diuretics. Other prospective studies are in progress to evaluate the effect of calcium antagonists on cardiovascular morbidity and mortality, and the progression of atherosclerosis in hypertensive patients. Calcium antagonists, especially the highly lipophilic amlodipine, lacidipine and nisoldipine, are shown to possess antioxidant properties. These drugs reduce the oxidation of LDL and its influx into the arterial wall, and reduce atherosclerotic lesions in animals. Platelet production of malondialdehyde, a marker of oxygen free radical formation, is suppressed by amlodipine, lacidipine or nifedipine in hypertensive patients. New evidence from long-term clinical trials of calcium antagonists indicates that these drugs can reduce the rate of progression of atherosclerosis in hypertensive and coronary heart disease patients. In the Regression Growth Evaluation Statin Study (REGRESS), co-administration of calcium antagonist, amlodipine or nifedipine with pravasatin caused a significant reduction in the appearance of new angiographic lesions. In the Verapamil in Hypertension and Atherosclerosis Study (VHAS), verapamil was more effective than chlorthalidone in promoting regression of thicker carotid lesions in parallel with a reduction in the incidence of cardiovascular events. In the Prospective Randomized Evaluation of the Vascular Effects of Norvasc Trial (PREVENT), amlodipine slowed the progression of early coronary atherosclerosis in patients with coronary artery disease. In a subprotocol of the Intervention as a Goal in the Hypertension Treatment (INSIGHT) study, nifedipine GITS significantly decreased intima

  10. Embryo implantation and GnRH antagonists: embryo implantation: the Rubicon for GnRH antagonists.

    PubMed

    Hernandez, E R

    2000-06-01

    When gonadotrophin-releasing hormone (GnRH) was discovered, the agonist and antagonist of GnRH were developed to control the release of FSH and LH by the gonadotrophs. More than 10 years of research were needed to develop a GnRH antagonist free of histamine release. Recent studies have shown that these GnRH antagonists are effective in preventing a rise in LH during ovarian stimulation in IVF. However, a decrease in ongoing pregnancies seems to suggest that implantation rates per transferred embryo are reduced in GnRH antagonist-stimulated cycles. In my opinion, these data highlight an area less well known to clinicians: the role of the GnRH antagonist at the cellular level in extrapituitary tissues. There are sufficient data in the literature suggesting that GnRH antagonist is an inhibitor of the cell cycle by decreasing the synthesis of growth factors. Given that, for folliculogenesis, blastomere formation and endometrium development, mitosis is everything; the interaction between the GnRH antagonist and the GnRH receptor (present in all these cells and tissues) may compromise the mitotic programme of these cells. This is the Rubicon for the GnRH antagonist: to demonstrate irrevocably that, at the minimal doses necessary to suppress LH release, it does not affect processes such as implantation, embryo development and folliculogenesis.

  11. [Antagonistic activity of novel green microalgae strain].

    PubMed

    Selivanova, E A; Ignatenko, M E; Nemtseva, N V

    2014-01-01

    Screening of novel microalgae strains for the presence of pronounced antagonistic (antibacterial) activity against opportunistic bacteria. 11 pure cultures of green unicellular algae isolated from fresh and salt basins of Orenburg region were studied for the presence of antagonistic activity against 4 test-strains of opportunistic bacteria by a photometric method. The effect of water extracts of microalgae Astermonas gracilis on the speed of self-purification of brine from Escherichia coli as well as antibacterial activity of peloid were evaluated under co-cultivation conditions. Pure cultures of green unicellular algae Scenedesmus obliquus (Turpin) Kütz, Scenedesmus magnus Meyen var. magnus, Pediastru duplex Meyen var. duplex, Chlorella vulgaris Bory, Monoraphidium arcuatum (Korschikov) Hindak (=Ankistrodesmus arcuatus Korschikov), Dictyosphaerium sp. had the most pronounced antagonistic activit against opportunistic bacteria. Water extract ofA. gracilis microalgae accelerated brine self-purification fro E. coli due to antibacterial effect. Peloid containing extracts of microorganism cells had a pronounced antibacterial effect against opportunistic bacteria. Antagonistic substances localized inside cells of microalgae increased the speed of allochthonic microorganism elimination that is one of the mechanisms of self-purification of a basin and antibacterial effect of peloid. The novel green microalgae strains studied due to the presence of pronounced antagonistic activity may have a wide practical application.

  12. Neuropharmacology of emesis in relation to clinical response.

    PubMed Central

    Costall, B.; Naylor, R. J.

    1992-01-01

    5-HT3 receptor antagonists such as ondansetron, granisetron, ICS205-930 and zacopride are highly effective in the ferret, cat or dog to prevent emesis caused by cisplatin and other chemotherapeutic agents, and radiation treatment. The anti-emetic effects may be mediated centrally in the area postrema and associated structures of the emetic reflex such as the nucleus tractus solitarius, which have a very high density of 5-HT3 receptors. Additional sites of action may be found on the 5-HT3 receptors located on the vagus nerve or enteric neuronal elements in the gastro-intestinal tract. The precise site(s) and mechanism(s) of action of different cytotoxic treatments to induce emesis remains to be determined, but appears to involve a common action on a 5-HT3 system. The 5-HT3 receptor antagonists do not impair normal behaviour and, in particular, fail to affect the extrapyramidal motor system and do not cause sedation. Of potential benefit, the 5-HT3 receptor antagonists have an anxiolytic profile of action in rodent and primate models. The 5-HT3 receptor antagonists are revealed as an important group of drugs to prevent emesis induced by a wide range of cytotoxic treatments. PMID:1467196

  13. Palonosetron Injection

    MedlinePlus

    ... that may occur several days after receiving certain chemotherapy medications. Palonosetron injection is in a class of medications called 5-HT3 receptor antagonists. It works by blocking the action of serotonin, a natural ...

  14. Tramadol

    MedlinePlus

    ... in a class of medications called opiate (narcotic) analgesics. It works by changing the way the brain ... promethazine; quinidine; rifampin (Rifadin, Rimactane, others); 5-HT3 receptor antagonists such as alosetron (Lotronex), dolasetron (Anzemet), granisetron ( ...

  15. High-affinity neuropeptide Y receptor antagonists.

    PubMed Central

    Daniels, A J; Matthews, J E; Slepetis, R J; Jansen, M; Viveros, O H; Tadepalli, A; Harrington, W; Heyer, D; Landavazo, A; Leban, J J

    1995-01-01

    Neuropeptide Y (NPY) is one of the most abundant peptide transmitters in the mammalian brain. In the periphery it is costored and coreleased with norepinephrine from sympathetic nerve terminals. However, the physiological functions of this peptide remain unclear because of the absence of specific high-affinity receptor antagonists. Three potent NPY receptor antagonists were synthesized and tested for their biological activity in in vitro, ex vivo, and in vivo functional assays. We describe here the effects of these antagonists inhibiting specific radiolabeled NPY binding at Y1 and Y2 receptors and antagonizing the effects of NPY in human erythroleukemia cell intracellular calcium mobilization perfusion pressure in the isolated rat kidney, and mean arterial blood pressure in anesthetized rats. PMID:7568074

  16. High-affinity neuropeptide Y receptor antagonists.

    PubMed

    Daniels, A J; Matthews, J E; Slepetis, R J; Jansen, M; Viveros, O H; Tadepalli, A; Harrington, W; Heyer, D; Landavazo, A; Leban, J J; Spaltenstein, A

    1995-09-26

    Neuropeptide Y (NPY) is one of the most abundant peptide transmitters in the mammalian brain. In the periphery it is costored and coreleased with norepinephrine from sympathetic nerve terminals. However, the physiological functions of this peptide remain unclear because of the absence of specific high-affinity receptor antagonists. Three potent NPY receptor antagonists were synthesized and tested for their biological activity in in vitro, ex vivo, and in vivo functional assays. We describe here the effects of these antagonists inhibiting specific radiolabeled NPY binding at Y1 and Y2 receptors and antagonizing the effects of NPY in human erythroleukemia cell intracellular calcium mobilization perfusion pressure in the isolated rat kidney, and mean arterial blood pressure in anesthetized rats.

  17. Skimmianine and related furoquinolines function as antagonists of 5-hydroxytryptamine receptors in animals.

    PubMed

    Cheng, J T; Chang, T K; Chen, I S

    1994-10-01

    1. Skimmianine, kokusaginine and confusameline, three furoquinolines extracted from the leaves of Evodia merrillii (Rutaceae), were investigated to characterize their selective effects on subtypes of 5-hydroxytryptamine (5-HT) receptors. 2. In the isolated membranes of rat cerebrocortex, using [3H]-5-HT and [3H]-ketanserin as radioligands, skimmianine and the two other furoquinolines displaced radioligand bindings in a concentration-dependent manner. Lower concentrations were required to affect [3H]-ketanserin binding than [3H]-5-HT binding in the order skimmianine > kokusaginine > confusameline. 3. Furoquinolines inhibited 5-HT-induced contraction mediated by 5-HT2 receptors in the presence of methiothepin in rat isolated aorta. Also, the combination of furoquinolines with ketanserin showed an additive antagonism. 4. These furoquinolines were inactive on the 5-carboxamidotryptamine-induced relaxation of guinea-pig ileum, a 5-HT1-mediated event. However, 5-HT-induced contraction via 5-HT2 receptors was reduced by these furoquinolines in a way similar to that in blood vessels. 5. The failure of these compounds to affect the 5-HT-induced Bezold-Jarisch-like reflex in anaesthetized rats, the major 5-HT3-mediated action, ruled out an action on 5-HT3 receptors. 6. The results obtained suggest that three furoquinoline alkaloids may act on 5-HT receptors in animals, more selectively to the 5-HT2 subtype, in the order of skimmianine > kokusaginine > confusameline.

  18. Evidence for 5-HT1B/1D and 5-HT2A receptors mediating constriction of the canine internal carotid circulation

    PubMed Central

    Centurión, David; Ortiz, Mario I; Sánchez-López, Araceli; De Vries, Peter; Saxena, Pramod R; Villalón, Carlos M

    2001-01-01

    The present study has investigated the preliminary pharmacological profile of the receptors mediating vasoconstriction to 5-hydroxytryptamine (5-HT) in the internal carotid bed of vagosympathectomised dogs. One minute intracarotid infusions of the agonists 5-HT (0.1–10 μg min−1), sumatriptan (0.3–10 μg min−1; 5-HT1B/1D), 5-methoxytryptamine (1–100 μg min−1; 5-HT1, 5-HT2, 5-HT4, 5-ht6 and 5-HT7) or DOI (0.31–10 μg min−1; 5-HT2), but not 5-carboxamidotryptamine (0.01–0.3 μg min−1; 5-HT1, 5-ht5A and 5-HT7), 1-(m-chlorophenyl)-biguanide (mCPBG; 1–1000 μg min−1; 5-HT3) or cisapride (1–1000 μg min−1; 5-HT4), resulted in dose-dependent decreases in internal carotid blood flow, without changing blood pressure or heart rate. The vasoconstrictor responses to 5-HT, which remained unaffected after saline, were resistant to blockade by i.v. administration of the antagonists ritanserin (100 μg kg−1; 5-HT2A/2B/2C) in combination with tropisetron (3000 μg kg−1; 5-HT3/4) or the cyclo-oxygenase inhibitor, indomethacin (5000 μg kg−1), but were abolished by the 5-HT1B/1D receptor antagonist, GR127935 (30 μg kg−1). Interestingly, after administration of GR127935, the subsequent administration of ritanserin unmasked a dose-dependent vasodilator component. GR127935 or saline did not practically modify the vasoconstrictor effects of 5-MeO-T. In animals receiving GR127935, the subsequent administration of ritanserin abolished the vasoconstrictor responses to 5-MeO-T unmasking a dose-dependent vasodilator component. The vasoconstriction induced by sumatriptan was antagonized by GR127935, but not by ritanserin. Furthermore, ritanserin (100 μg kg−1) or ketanserin (100 μg kg−1; 5-HT2A), but not GR127935, abolished DOI-induced vasoconstrictor responses. The above results suggest that 5-HT-induced internal carotid vasoconstriction is predominantly mediated by 5-HT1B/1D and 5-HT2A receptors

  19. Antagonistic Interactions among Marine Pelagic Bacteria

    PubMed Central

    Long, Richard A.; Azam, Farooq

    2001-01-01

    Recent studies suggest that bacterial abundance and species diversity in the ocean's water column are variable at the millimeter scale, apparently in response to the small-scale heterogeneity in the distribution of organic matter. We hypothesized that bacterium-bacterium antagonistic interactions may contribute to variations in community structure at the microscale. We examined each of the 86 isolates for their inhibition of growth of the remaining 85 isolates by the Burkholder agar diffusion assay. More than one-half of the isolates expressed antagonistic activity, and this trait was more common with particle-associated bacteria than with free-living bacteria. This was exemplified by members of the α subclass of the class Proteobacteria (α-proteobacteria), in which production of antagonistic molecules was dominated by attached bacteria. We found that γ-proteobacteria (members of the orders Alteromonadales and Vibrionales) are the most prolific producers of inhibitory materials and also the most resilient to them, while members of the Bacteriodetes were the organisms that were least productive and most sensitive to antagonistic interactions. Widespread interspecies growth inhibition is consistent with the role of this phenomenon in structuring bacterial communities at the microscale. Furthermore, our results suggest that bacteria from pelagic marine particles may be an underutilized source of novel antibiotics. PMID:11679315

  20. Treatment of established postoperative nausea and vomiting: a quantitative systematic review

    PubMed Central

    Kazemi-Kjellberg, Faranak; Henzi, Iris; Tramèr, Martin R

    2001-01-01

    Background The relative efficacy of antiemetics for the treatment of postoperative nausea and vomiting (PONV) is poorly understood. Methods Systematic search (MEDLINE, Embase, Cochrane Library, bibliographies, any language, to 8.2000) for randomised comparisons of antiemetics with any comparator for the treatment of established PONV. Dichotomous data on prevention of further nausea and vomiting, and on side effects were combined using a fixed effect model. Results In seven trials (1,267 patients), 11 different antiemetics were tested without placebos; these data were not further analysed. Eighteen trials (3,809) had placebo controls. Dolasetron 12.5–100 mg, granisetron 0.1–3 mg, tropisetron 0.5–5 mg, and ondansetron 1–8 mg prevented further vomiting with little evidence of dose-responsiveness; with all regimens, absolute risk reductions compared with placebo were 20%–30%. The anti-nausea effect was less pronounced. Headache was dose-dependent. Results on propofol were contradictory. The NK1 antagonist GR205171, isopropyl alcohol vapor, metoclopramide, domperidone, and midazolam were tested in one trial each with a limited number of patients. Conclusions Of 100 vomiting surgical patients receiving a 5-HT3 receptor antagonist, 20 to 30 will stop vomiting who would not have done so had they received a placebo; less will profit from the anti-nausea effect. There is a lack of evidence for a clinically relevant dose-response; minimal effective doses may be used. There is a discrepancy between the plethora of trials on prevention of PONV and the paucity of trials on treatment of established symptoms. Valid data on the therapeutic efficacy of classic antiemetics, which have been used for decades, are needed. PMID:11734064

  1. Antagonistic and synergistic interactions among predators.

    PubMed

    Huxel, Gary R

    2007-08-01

    The structure and dynamics of food webs are largely dependent upon interactions among consumers and their resources. However, interspecific interactions such as intraguild predation and interference competition can also play a significant role in the stability of communities. The role of antagonistic/synergistic interactions among predators has been largely ignored in food web theory. These mechanisms influence predation rates, which is one of the key factors regulating food web structure and dynamics, thus ignoring them can potentially limit understanding of food webs. Using nonlinear models, it is shown that critical aspects of multiple predator food web dynamics are antagonistic/synergistic interactions among predators. The influence of antagonistic/synergistic interactions on coexistence of predators depended largely upon the parameter set used and the degree of feeding niche differentiation. In all cases when there was no effect of antagonism or synergism (a ( ij )=1.00), the predators coexisted. Using the stable parameter set, coexistence occurred across the range of antagonism/synergism used. However, using the chaotic parameter strong antagonism resulted in the extinction of one or both species, while strong synergism tended to coexistence. Whereas using the limit cycle parameter set, coexistence was strongly dependent on the degree of feeding niche overlap. Additionally increasing the degree of feeding specialization of the predators on the two prey species increased the amount of parameter space in which coexistence of the two predators occurred. Bifurcation analyses supported the general pattern of increased stability when the predator interaction was synergistic and decreased stability when it was antagonistic. Thus, synergistic interactions should be more common than antagonistic interactions in ecological systems.

  2. Antagonist-Elicited Cannabis Withdrawal in Humans

    PubMed Central

    Gorelick, David A.; Goodwin, Robert S.; Schwilke, Eugene; Schwope, David M.; Darwin, William D.; Kelly, Deanna L.; McMahon, Robert P.; Liu, Fang; Ortemann-Renon, Catherine; Bonnet, Denis; Huestis, Marilyn A.

    2013-01-01

    Cannabinoid CB1 receptor antagonists have potential therapeutic benefits, but antagonist-elicited cannabis withdrawal has not been reported in humans. Ten male daily cannabis smokers received 8 days of increasingly frequent 20-mg oral Δ9-tetrahydrocannabinol (THC) dosages (40–120 mg/d) around-the-clock to standardize cannabis dependence while residing on a closed research unit. On the ninth day, double-blind placebo or 20- (suggested therapeutic dose) or 40-mg oral rimonabant, a CB1-cannabinoid receptor antagonist, was administered. Cannabis withdrawal signs and symptoms were assessed before and for 23.5 hours after rimonabant. Rimonabant, THC, and 11-hydroxy-THC plasma concentrations were quantified by mass spectrometry. The first 6 subjects received 20-mg rimonabant (1 placebo); the remaining 4 subjects received 40-mg rimonabant (1 placebo). Fourteen subjects enrolled; 10 completed before premature termination because of withdrawal of rimonabant from clinical development. Three of 5 subjects in the 20-mg group, 1 of 3 in the 40-mg group, and none of 2 in the placebo group met the prespecified withdrawal criterion of 150% increase or higher in at least 3 visual analog scales for cannabis withdrawal symptoms within 3 hours of rimonabant dosing. There were no significant associations between visual analog scale, heart rate, or blood pressure changes and peak rimonabant plasma concentration, area-under-the-rimonabant-concentration-by-time curve (0–8 hours), or peak rimonabant/THC or rimonabant/(THC + 11-hydroxy-THC) plasma concentration ratios. In summary, prespecified criteria for antagonist-elicited cannabis withdrawal were not observed at the 20- or 40-mg rimonabant doses. These data do not preclude antagonist-elicited withdrawal at higher rimonabant doses. PMID:21869692

  3. Antagonist-elicited cannabis withdrawal in humans.

    PubMed

    Gorelick, David A; Goodwin, Robert S; Schwilke, Eugene; Schwope, David M; Darwin, William D; Kelly, Deanna L; McMahon, Robert P; Liu, Fang; Ortemann-Renon, Catherine; Bonnet, Denis; Huestis, Marilyn A

    2011-10-01

    Cannabinoid CB1 receptor antagonists have potential therapeutic benefits, but antagonist-elicited cannabis withdrawal has not been reported in humans. Ten male daily cannabis smokers received 8 days of increasingly frequent 20-mg oral Δ⁹-tetrahydrocannabinol (THC) dosages (40-120 mg/d) around-the-clock to standardize cannabis dependence while residing on a closed research unit. On the ninth day, double-blind placebo or 20- (suggested therapeutic dose) or 40-mg oral rimonabant, a CB1-cannabinoid receptor antagonist, was administered. Cannabis withdrawal signs and symptoms were assessed before and for 23.5 hours after rimonabant. Rimonabant, THC, and 11-hydroxy-THC plasma concentrations were quantified by mass spectrometry. The first 6 subjects received 20-mg rimonabant (1 placebo); the remaining 4 subjects received 40-mg rimonabant (1 placebo). Fourteen subjects enrolled; 10 completed before premature termination because of withdrawal of rimonabant from clinical development. Three of 5 subjects in the 20-mg group, 1 of 3 in the 40-mg group, and none of 2 in the placebo group met the prespecified withdrawal criterion of 150% increase or higher in at least 3 visual analog scales for cannabis withdrawal symptoms within 3 hours of rimonabant dosing. There were no significant associations between visual analog scale, heart rate, or blood pressure changes and peak rimonabant plasma concentration, area-under-the-rimonabant-concentration-by-time curve (0-8 hours), or peak rimonabant/THC or rimonabant/(THC + 11-hydroxy-THC) plasma concentration ratios. In summary, prespecified criteria for antagonist-elicited cannabis withdrawal were not observed at the 20- or 40-mg rimonabant doses. These data do not preclude antagonist-elicited withdrawal at higher rimonabant doses.

  4. Combining Elements from Two Antagonists of Formyl Peptide Receptor 2 Generates More Potent Peptidomimetic Antagonists.

    PubMed

    Skovbakke, Sarah Line; Holdfeldt, André; Nielsen, Christina; Hansen, Anna Mette; Perez-Gassol, Iris; Dahlgren, Claes; Forsman, Huamei; Franzyk, Henrik

    2017-08-24

    Structural optimization of a peptidomimetic antagonist of formyl peptide receptor 2 (FPR2) was explored by an approach involving combination of elements from the two most potent FPR2 antagonists described: a Rhodamine B-conjugated 10-residue gelsonin-derived peptide (i.e., PBP10, RhB-QRLFQVKGRR-OH) and the palmitoylated α-peptide/β-peptoid hybrid Pam-(Lys-βNspe)6-NH2. This generated an array of hybrid compounds from which a new subclass of receptor-selective antagonists was identified. The most potent representatives displayed activity in the low nanomolar range. The resulting stable and potent FPR2-selective antagonists (i.e., RhB-(Lys-βNphe)n-NH2; n = 4-6) are expected to become valuable tools in further elucidation of the physiological role of FPR2 in health and disease.

  5. Palonosetron for the treatment of chemotherapy-induced nausea and vomiting.

    PubMed

    Navari, Rudolph M

    2014-12-01

    Chemotherapy-induced nausea and vomiting (CINV) is associated with a significant deterioration in quality of life. The emetogenicity of the chemotherapeutic agents, repeated chemotherapy cycles, and patient risk factors significantly influence CINV. The introduction of 5-hydroxytryptamine-3 (5-HT3) receptor antagonists has been a major factor in the improvement of the prevention of chemotherapy-induced acute and delayed emesis. Palonosetron , a second-generation 5-HT3 receptor antagonist with a different half-life, a different binding capacity, and a different mechanism of action than the first-generation 5-HT3 receptor antagonists appears to be the most effective agent in this drug class. Palonosetron's chemistry, pharmacodynamics, pharmacokinetics, metabolism, clinical efficacy, including comparison with other antiemetics, role in controlling nausea, potential role in multi-day chemotherapy and bone marrow transplantation, and overall safety are discussed. The clinical data in the literature have established palonosetron as the 5-HT3 receptor antagonist of choice in terms of efficacy and safety for the prevention of CINV for patients receiving moderately or highly emetogenic chemotherapy. Three international guidelines have listed palonosetron as the preferred 5-HT3 receptor antagonist. Due to its higher efficacy, the use of palonosetron may be more cost effective compared to the generic first-generation 5-HT3 receptor antagonists. Clinical organizations' pharmacy and formulary committees should consider efficacy when making recommendations for agents for the prevention of CINV.

  6. Progress in corticotropin-releasing factor-1 antagonist development

    PubMed Central

    Zorrilla, Eric P.; Koob, George F.

    2010-01-01

    Corticotropin-releasing factor (CRF) receptor antagonists have been sought since the stress-secreted peptide was isolated in 1981. Although evidence suggests the limited efficacy of CRF1 antagonists as antidepressants, CRF1 antagonists might be novel pharmacotherapies for anxiety and addiction. Progress in understanding the two-domain model of ligand–receptor interactions for CRF family receptors might yield chemically novel CRF1 receptor antagonists, including peptide CRF1 antagonists, antagonists with signal transduction selectivity and nonpeptide CRF1 antagonists that act via the extracellular (rather than transmembrane) domains. Novel ligands that conform to prevalent pharmacophore and exhibit drug-like pharmacokinetic properties have been identified. The therapeutic utility of CRF1 antagonists should soon be clearer: several small molecules are currently in Phase II/III clinical trials for depression, anxiety and irritable bowel syndrome. PMID:20206287

  7. Novel benzimidazole-based MCH R1 antagonists.

    PubMed

    Carpenter, Andrew J; Al-Barazanji, Kamal A; Barvian, Kevin K; Bishop, Michael J; Britt, Christy S; Cooper, Joel P; Goetz, Aaron S; Grizzle, Mary K; Hertzog, Donald L; Ignar, Diane M; Morgan, Ronda O; Peckham, Gregory E; Speake, Jason D; Swain, Will R

    2006-10-01

    The identification of an MCH R1 antagonist screening hit led to the optimization of a class of benzimidazole-based MCH R1 antagonists. Structure-activity relationships and efforts to optimize pharmacokinetic properties are detailed along with the demonstration of the effectiveness of an MCH R1 antagonist in an animal model of obesity.

  8. Effect of a Hypocretin/Orexin Antagonist on Neurocognitive Performance

    DTIC Science & Technology

    2010-09-30

    a novel hypocretiniorexin antagonist, almorexant (ALM), to a standard hypnotic , zolpidem (ZOL), and placebo (PBO) on neurocognitive performance at...Placebo-Controlled, Randomized, Parallel- Group Study Comparing the Effect of a Novel HypocretiniOrexin Antagonist (Almorexant) Versus a Standard Hypnotic ...Group Study Comparing the Effect of a Novel HypocretiniOrexin Antagonist (Almorexant) Versus a Standard Hypnotic (Zolpidem) and Placebo on

  9. The treatment of hyponatraemia using vasopressin antagonists.

    PubMed

    Gross, P; Palm, C

    2000-03-01

    Hyponatraemia is a frequent electrolyte disorder. It is primarily attributable to vasopressin excess plus sustained fluid intake. Hyponatraemia causes CNS symptoms, especially during the first 2-4 days; these symptoms are related to brain swelling. Hyponatraemia occurs in the setting of liver cirrhosis and congestive cardiac failure, in which it is related to stimulation by low arterial blood pressure acting through baroreceptors. Hyponatraemia also occurs in the syndrome of inappropriate antidiuretic hormone secretion, usually from neoplasms releasing vasopressin. The conventional treatment of hyponatraemia used to be fluid restriction and treatment of the underlying disorder. This kind of treatment has been unreliable, cumbersome and difficult to comply with for the patient. In the future, effective vasopressin V2 antagonists will become available for clinical use in the treatment of hyponatraemia, and are expected to improve the management of hyponatraemia. Pharmacological characteristics and observations of biological effects of three antagonists are reported in the present article.

  10. Development of Kappa Opioid Receptor Antagonists

    PubMed Central

    Carroll, F. Ivy; Carlezon, William A.

    2013-01-01

    Kappa opioid receptors (KORs) belong to the G-protein coupled class of receptors (GPCRs). They are activated by the endogenous opioid peptide dynorphin (DYN) and expressed at particularly high levels within brain areas implicated in modulation of motivation, emotion, and cognitive function. Chronic activation of KORs in animal models has maladaptive effects including increases in behaviors that reflect depression, the propensity to engage in drug-seeking behavior, and drug craving. The fact that KOR activation has such a profound influence on behaviors often triggered by stress has led to interest in selective KOR antagonists as potential therapeutic agents. This perspective provides a description of preclinical research conducted in the development of several different classes of selective KOR antagonists, a summary of the clinical studies conducted thus far, and recommendations for the type of work needed in the future to determine if these agents would be useful as pharmacotherapies for neuropsychiatric illness. PMID:23360448

  11. [PAF antagonistic benzofuran neolignans from Piper kadsura].

    PubMed

    Ma, Y; Han, G Q; Wang, Y Y

    1993-01-01

    In a continuing search for PAF antagonists, five benzofuran neolignans have been isolated from the aerial part of Piper kadsura (Choisy) Ohwi, a Chinese traditional drug used for the treatment of inflammation and rheumatic conditions. The structure determination was based upon spectroscopic analysis. Two of the neolignans were found to have new structures and were named as (-)-denudatin B (the enantiomer of denudatin B, II) and kadsurenin M (7S,8S-3,4,3'-trimethoxy-7'-oxo-nor-8',9'-7.O. 4',8,5'-neolignan, V). The known compounds kadsurenon (I), (-)-acuminatin(III) and (+)-licarin A(IV) were also obtained from the same source. (-)-Denudatin B (II) showed potent PAF antagonistic activity in 3H-PAF receptor binding assay.

  12. Interactions of Freshwater Cyanobacteria with Bacterial Antagonists

    PubMed Central

    Beier, Sara; Grabherr, Manfred

    2017-01-01

    ABSTRACT Cyanobacterial and algal mass development, or blooms, have severe effects on freshwater and marine systems around the world. Many of these phototrophs produce a variety of potent toxins, contribute to oxygen depletion, and affect water quality in several ways. Coexisting antagonists, such as cyanolytic bacteria, hold the potential to suppress, or even terminate, such blooms, yet the nature of this interaction is not well studied. We isolated 31 cyanolytic bacteria affiliated with the genera Pseudomonas, Stenotrophomonas, Acinetobacter, and Delftia from three eutrophic freshwater lakes in Sweden and selected four phylogenetically diverse bacterial strains with strong-to-moderate lytic activity. To characterize their functional responses to the presence of cyanobacteria, we performed RNA sequencing (RNA-Seq) experiments on coculture incubations, with an initial predator-prey ratio of 1:1. Genes involved in central cellular pathways, stress-related heat or cold shock proteins, and antitoxin genes were highly expressed in both heterotrophs and cyanobacteria. Heterotrophs in coculture expressed genes involved in cell motility, signal transduction, and putative lytic activity. l,d-Transpeptidase was the only significantly upregulated lytic gene in Stenotrophomonas rhizophila EK20. Heterotrophs also shifted their central metabolism from the tricarboxylic acid cycle to the glyoxylate shunt. Concurrently, cyanobacteria clearly show contrasting antagonistic interactions with the four tested heterotrophic strains, which is also reflected in the physical attachment to their cells. In conclusion, antagonistic interactions with cyanobacteria were initiated within 24 h, and expression profiles suggest varied responses for the different cyanobacteria and studied cyanolytes. IMPORTANCE Here, we present how gene expression profiles can be used to reveal interactions between bloom-forming freshwater cyanobacteria and antagonistic heterotrophic bacteria. Species

  13. TRPV1 antagonists as potential antitussive agents.

    PubMed

    McLeod, Robbie L; Correll, Craig C; Jia, Yanlin; Anthes, John C

    2008-01-01

    Cough is an important defensive pulmonary reflex that removes irritants, fluids, or foreign materials from the airways. However, when cough is exceptionally intense or when it is chronic and/or nonproductive it may require pharmacologic suppression. For many patients, antitussive therapies consist of OTC products with inconsequential efficacies. On the other hand, the prescription antitussive market is dominated by older opioid drugs such as codeine. Unfortunately, "codeine-like" drugs suppress cough at equivalent doses that also often produce significant ancillary liabilities such as GI constipation, sedation, and respiratory depression. Thus, the discovery of a novel and effective antitussive drug with an improved side effect profile relative to codeine would fulfill an unmet clinical need in the treatment of cough. Afferent pulmonary nerves are endowed with a multitude of potential receptor targets, including TRPV1, that could act to attenuate cough. The evidence linking TRPV1 to cough is convincing. TRPV1 receptors are found on sensory respiratory nerves that are important in the generation of the cough reflex. Isolated pulmonary vagal afferent nerves are responsive to TRPV1 stimulation. In vivo, TRPV1 agonists such as capsaicin elicit cough when aerosolized and delivered to the lungs. Pertinent to the debate on the potential use of TRPV1 antagonist as antitussive agents are the observations that airway afferent nerves become hypersensitive in diseased and inflamed lungs. For example, the sensitivity of capsaicin-induced cough responses following upper respiratory tract infection and in airway inflammatory diseases such as asthma and COPD is increased relative to that of control responses. Indeed, we have demonstrated that TRPV1 antagonism can attenuate antigen-induced cough in the allergic guinea pig. However, it remains to be determined if the emerging pharmacologic profile of TRPV1 antagonists will translate into a novel human antitussive drug. Current

  14. Interactions of Freshwater Cyanobacteria with Bacterial Antagonists.

    PubMed

    Osman, Omneya Ahmed; Beier, Sara; Grabherr, Manfred; Bertilsson, Stefan

    2017-04-01

    Cyanobacterial and algal mass development, or blooms, have severe effects on freshwater and marine systems around the world. Many of these phototrophs produce a variety of potent toxins, contribute to oxygen depletion, and affect water quality in several ways. Coexisting antagonists, such as cyanolytic bacteria, hold the potential to suppress, or even terminate, such blooms, yet the nature of this interaction is not well studied. We isolated 31 cyanolytic bacteria affiliated with the genera Pseudomonas, Stenotrophomonas, Acinetobacter, and Delftia from three eutrophic freshwater lakes in Sweden and selected four phylogenetically diverse bacterial strains with strong-to-moderate lytic activity. To characterize their functional responses to the presence of cyanobacteria, we performed RNA sequencing (RNA-Seq) experiments on coculture incubations, with an initial predator-prey ratio of 1:1. Genes involved in central cellular pathways, stress-related heat or cold shock proteins, and antitoxin genes were highly expressed in both heterotrophs and cyanobacteria. Heterotrophs in coculture expressed genes involved in cell motility, signal transduction, and putative lytic activity. l,d-Transpeptidase was the only significantly upregulated lytic gene in Stenotrophomonas rhizophila EK20. Heterotrophs also shifted their central metabolism from the tricarboxylic acid cycle to the glyoxylate shunt. Concurrently, cyanobacteria clearly show contrasting antagonistic interactions with the four tested heterotrophic strains, which is also reflected in the physical attachment to their cells. In conclusion, antagonistic interactions with cyanobacteria were initiated within 24 h, and expression profiles suggest varied responses for the different cyanobacteria and studied cyanolytes.IMPORTANCE Here, we present how gene expression profiles can be used to reveal interactions between bloom-forming freshwater cyanobacteria and antagonistic heterotrophic bacteria. Species-specific responses in

  15. NMDA Receptor Antagonists for Treatment of Depression

    PubMed Central

    Ates-Alagoz, Zeynep; Adejare, Adeboye

    2013-01-01

    Depression is a psychiatric disorder that affects millions of people worldwide. Individuals battling this disorder commonly experience high rates of relapse, persistent residual symptoms, functional impairment, and diminished well-being. Medications have important utility in stabilizing moods and daily functions of many individuals. However, only one third of patients had considerable improvement with a standard antidepressant after 2 months and all patients had to deal with numerous side effects. The N-methyl-d-aspartate (NMDA) receptor family has received special attention because of its critical role in psychiatric disorders. Direct targeting of the NMDA receptor could result in more rapid antidepressant effects. Antidepressant-like effects of NMDA receptor antagonists have been demonstrated in different animal models. MK-801 (a use-dependent channel blocker), and CGP 37849 (an NMDA receptor antagonist) have shown antidepressant properties in preclinical studies, either alone or combined with traditional antidepressants. A recent development is use of ketamine clinically for refractory depression. The purpose of this review is to examine and analyze current literature on the role of NMDA receptor antagonists for treatment of depression and whether this is a feasible route in drug discovery. PMID:24276119

  16. Medicinal Chemistry of Competitive Kainate Receptor Antagonists

    PubMed Central

    2010-01-01

    Kainic acid (KA) receptors belong to the group of ionotropic glutamate receptors and are expressed throughout in the central nervous system (CNS). The KA receptors have been shown to be involved in neurophysiological functions such as mossy fiber long-term potentiation (LTP) and synaptic plasticity and are thus potential therapeutic targets in CNS diseases such as schizophrenia, major depression, neuropathic pain and epilepsy. Extensive effort has been made to develop subtype-selective KA receptor antagonists in order to elucidate the physiological function of each of the five subunits known (GluK1−5). However, to date only selective antagonists for the GluK1 subunit have been discovered, which underlines the strong need for continued research in this area. The present review describes the structure−activity relationship and pharmacological profile for 10 chemically distinct classes of KA receptor antagonists comprising, in all, 45 compounds. To the medicinal chemist this information will serve as reference guidance as well as an inspiration for future effort in this field. PMID:22778857

  17. Medicinal chemistry of competitive kainate receptor antagonists.

    PubMed

    Larsen, Ann M; Bunch, Lennart

    2011-02-16

    Kainic acid (KA) receptors belong to the group of ionotropic glutamate receptors and are expressed throughout in the central nervous system (CNS). The KA receptors have been shown to be involved in neurophysiological functions such as mossy fiber long-term potentiation (LTP) and synaptic plasticity and are thus potential therapeutic targets in CNS diseases such as schizophrenia, major depression, neuropathic pain and epilepsy. Extensive effort has been made to develop subtype-selective KA receptor antagonists in order to elucidate the physiological function of each of the five subunits known (GluK1-5). However, to date only selective antagonists for the GluK1 subunit have been discovered, which underlines the strong need for continued research in this area. The present review describes the structure-activity relationship and pharmacological profile for 10 chemically distinct classes of KA receptor antagonists comprising, in all, 45 compounds. To the medicinal chemist this information will serve as reference guidance as well as an inspiration for future effort in this field.

  18. Pharmacological analysis of calcium antagonist receptors

    SciTech Connect

    Reynolds, I.J.

    1987-01-01

    This work focuses on two aspects of the action of calcium antagonist drugs, namely, the interaction of drugs with receptors for verapamil-like calcium antagonists, and the interactions of drugs with voltage-sensitive calcium fluxes in rat brain synaptosomes. From binding studies I have found that the ligand of choice for labeling the verapamil receptor is (-)(/sup 3/H)desmethoxy-verapamil. This drug labels potently, reversibly and stereoselectively two receptors in membranes prepared from rat brain and rabbit skeletal muscle tissues. In equilibrium studies dihydropyridine calcium antagonists interact in a non-competitive fashion, while many non-DHPs are apparently competitive. In-depth kinetic studies in skeletal muscle membranes indicate that the two receptors are linked in a negative heterotropic fashion, and that low-affinity binding of (-) (/sup 3/H)desmethoxy-verapamil may be to the diltiazem receptor. However, these studies were not able to distinguish between the hypothesis that diltiazem binds to spatially separate, allosterically coupled receptors, and the hypothesis that diltiazem binds to a subsite of the verapamil receptor.

  19. From the Cover: Glutamate antagonists limit tumor growth

    NASA Astrophysics Data System (ADS)

    Rzeski, Wojciech; Turski, Lechoslaw; Ikonomidou, Chrysanthy

    2001-05-01

    Neuronal progenitors and tumor cells possess propensity to proliferate and to migrate. Glutamate regulates proliferation and migration of neurons during development, but it is not known whether it influences proliferation and migration of tumor cells. We demonstrate that glutamate antagonists inhibit proliferation of human tumor cells. Colon adenocarcinoma, astrocytoma, and breast and lung carcinoma cells were most sensitive to the antiproliferative effect of the N-methyl-D-aspartate antagonist dizocilpine, whereas breast and lung carcinoma, colon adenocarcinoma, and neuroblastoma cells responded most favorably to the -amino-3-hydroxy-5-methyl-4-isoxazole-propionate antagonist GYKI52466. The antiproliferative effect of glutamate antagonists was Ca2+ dependent and resulted from decreased cell division and increased cell death. Morphological alterations induced by glutamate antagonists in tumor cells consisted of reduced membrane ruffling and pseudopodial protrusions. Furthermore, glutamate antagonists decreased motility and invasive growth of tumor cells. These findings suggest anticancer potential of glutamate antagonists.

  20. Investigation of orexin-2 selective receptor antagonists: Structural modifications resulting in dual orexin receptor antagonists.

    PubMed

    Skudlarek, Jason W; DiMarco, Christina N; Babaoglu, Kerim; Roecker, Anthony J; Bruno, Joseph G; Pausch, Mark A; O'Brien, Julie A; Cabalu, Tamara D; Stevens, Joanne; Brunner, Joseph; Tannenbaum, Pamela L; Wuelfing, W Peter; Garson, Susan L; Fox, Steven V; Savitz, Alan T; Harrell, Charles M; Gotter, Anthony L; Winrow, Christopher J; Renger, John J; Kuduk, Scott D; Coleman, Paul J

    2017-03-15

    In an ongoing effort to explore the use of orexin receptor antagonists for the treatment of insomnia, dual orexin receptor antagonists (DORAs) were structurally modified, resulting in compounds selective for the OX2R subtype and culminating in the discovery of 23, a highly potent, OX2R-selective molecule that exhibited a promising in vivo profile. Further structural modification led to an unexpected restoration of OX1R antagonism. Herein, these changes are discussed and a rationale for selectivity based on computational modeling is proposed.

  1. Combination decongestion therapy in hospitalized heart failure: loop diuretics, mineralocorticoid receptor antagonists and vasopressin antagonists.

    PubMed

    Vaduganathan, Muthiah; Mentz, Robert J; Greene, Stephen J; Senni, Michele; Sato, Naoki; Nodari, Savina; Butler, Javed; Gheorghiade, Mihai

    2015-01-01

    Congestion is the most common reason for admissions and readmissions for heart failure (HF). The vast majority of hospitalized HF patients appear to respond readily to loop diuretics, but available data suggest that a significant proportion are being discharged with persistent evidence of congestion. Although novel therapies targeting congestion should continue to be developed, currently available agents may be utilized more optimally to facilitate complete decongestion. The combination of loop diuretics, natriuretic doses of mineralocorticoid receptor antagonists and vasopressin antagonists represents a regimen of currently available therapies that affects early and persistent decongestion, while limiting the associated risks of electrolyte disturbances, hemodynamic fluctuations, renal dysfunction and mortality.

  2. Antagonistic functional duality of cancer genes.

    PubMed

    Stepanenko, A A; Vassetzky, Y S; Kavsan, V M

    2013-10-25

    Cancer evolution is a stochastic process both at the genome and gene levels. Most of tumors contain multiple genetic subclones, evolving in either succession or in parallel, either in a linear or branching manner, with heterogeneous genome and gene alterations, extensively rewired signaling networks, and addicted to multiple oncogenes easily switching with each other during cancer progression and medical intervention. Hundreds of discovered cancer genes are classified according to whether they function in a dominant (oncogenes) or recessive (tumor suppressor genes) manner in a cancer cell. However, there are many cancer "gene-chameleons", which behave distinctly in opposite way in the different experimental settings showing antagonistic duality. In contrast to the widely accepted view that mutant NADP(+)-dependent isocitrate dehydrogenases 1/2 (IDH1/2) and associated metabolite 2-hydroxyglutarate (R)-enantiomer are intrinsically "the drivers" of tumourigenesis, mutant IDH1/2 inhibited, promoted or had no effect on cell proliferation, growth and tumorigenicity in diverse experiments. Similar behavior was evidenced for dozens of cancer genes. Gene function is dependent on genetic network, which is defined by the genome context. The overall changes in karyotype can result in alterations of the role and function of the same genes and pathways. The diverse cell lines and tumor samples have been used in experiments for proving gene tumor promoting/suppressive activity. They all display heterogeneous individual karyotypes and disturbed signaling networks. Consequently, the effect and function of gene under investigation can be opposite and versatile in cells with different genomes that may explain antagonistic duality of cancer genes and the cell type- or the cellular genetic/context-dependent response to the same protein. Antagonistic duality of cancer genes might contribute to failure of chemotherapy. Instructive examples of unexpected activity of cancer genes and

  3. Neuromuscular adaptations following antagonist resisted training.

    PubMed

    MacKenzie, Sasho J; Rannelli, Luke A; Yurchevich, Jordan J

    2010-01-01

    The purpose was to assess a novel form of strength training, antagonist resisted training (ART), with potential use in microgravity and athletic rehabilitation settings. ART uses the force from antagonist muscles, during cocontractions, as the source of resistance for the agonists. Strength and electromyography (EMG) measurements were recorded before and after a 6-week training program during which participants trained the left arm while the right arm served as a control. Training was designed so that the elbow extensors (antagonists) served as resistance for the elbow flexors (agonists). Elbow flexor and extensor strengths were measured during maximal isometric contractions with the elbow fixed at 90 degrees. EMG was recorded from the biceps brachii and lateral head of the triceps brachii during all strength tests. EMG was also recorded from both muscles during a maximal isometric cocontraction of the elbow flexors and extensors. Elbow flexion strength increased significantly for the trained arm (5.8%) relative to the control (0.5%) (p = 0.003). Elbow extension strength of the trained limb also increased significantly (8.5%) relative to the control (4.5%) (p = 0.029). Biceps and triceps EMG, during maximum strength tests, increased significantly for the trained arm (18.5 and 18.6%) relative to the control (0.5 and -5.2%) (p = 0.035 and p = 0.01). Biceps and triceps EMG, during maximum cocontraction tests, increased significantly for the trained arm (30.1 and 61.1%) relative to the control (9.2 and 1.1%) (p = 0.042 and p = 0.0005). ART was found to increase strength and therefore could be an effective form of resistance training. Because it requires no equipment, ART may be especially applicable in microgravity environments, which have space and weight constraints.

  4. Agonists and antagonists for P2 receptors

    PubMed Central

    Jacobson, Kenneth A.; Costanzi, Stefano; Joshi, Bhalchandra V.; Besada, Pedro; Shin, Dae Hong; Ko, Hyojin; Ivanov, Andrei A.; Mamedova, Liaman

    2015-01-01

    Recent work has identified nucleotide agonists selective for P2Y1, P2Y2 and P2Y6 receptors and nucleotide antagonists selective for P2Y1, P2Y12 and P2X1 receptors. Selective non-nucleotide antagonists have been reported for P2Y1, P2Y2, P2Y6, P2Y12, P2Y13, P2X2/3/P2X3 and P2X7 receptors. For example, the dinucleotide INS 37217 (Up4dC) potently activates the P2Y2 receptor, and the non-nucleotide antagonist A-317491 is selective for P2X2/3/P2X3 receptors. Nucleotide analogues in which the ribose moiety is substituted by a variety of novel ring systems, including conformation-ally locked moieties, have been synthesized as ligands for P2Y receptors. The focus on conformational factors of the ribose-like moiety allows the inclusion of general modifications that lead to enhanced potency and selectivity. At P2Y1,2,4,11 receptors, there is a preference for the North conformation as indicated with (N)-methanocarba analogues. The P2Y1 antagonist MRS2500 inhibited ADP-induced human platelet aggregation with an IC50 of 0.95 nM. MRS2365, an (N)-methanocarba analogue of 2-MeSADP, displayed potency (EC50) of 0.4 nM at the P2Y1 receptor, with >10 000-fold selectivity in comparison to P2Y12 and P2Y13 receptors. At P2Y6 receptors there is a dramatic preference for the South conformation. Three-dimensional structures of P2Y receptors have been deduced from structure activity relationships (SAR), mutagenesis and modelling studies. Detailed three-dimensional structures of P2X receptors have not yet been proposed. PMID:16805423

  5. Muscarinic Receptor Antagonists: Effects on Pulmonary Function

    PubMed Central

    Buels, Kalmia S.

    2014-01-01

    In healthy lungs, muscarinic receptors control smooth muscle tone, mucus secretion, vasodilation, and inflammation. In chronic obstructive pulmonary disease (COPD) and asthma, cholinergic mechanisms contribute to increased bronchoconstriction and mucus secretion that limit airflow. This chapter reviews neuronal and nonneuronal sources of acetylcholine in the lung and the expression and role of M1, M2, and M3 muscarinic receptor subtypes in lung physiology. It also discusses the evidence for and against the role of parasympathetic nerves in asthma, and the current use and therapeutic potential of muscarinic receptor antagonists in COPD and asthma. PMID:22222705

  6. Azetidinones as Vasopressin V1a Antagonists

    PubMed Central

    Guillon, Christophe D.; Koppel, Gary A.; Brownstein, Michael J.; Chaney, Michael O.; Ferris, Craig F.; Lu, Shi-fang; Fabio, Karine M.; Miller, Marvin J.; Heindel, Ned D.; Hunden, David C.; Cooper, Robin D. G.; Kaldor, Stephen W.; Skelton, Jeffrey J.; Dressman, Bruce A.; Clay, Michael P.; Steinberg, Mitchell I.; Bruns, Robert F.; Simon, Neal G.

    2007-01-01

    The azetidinone LY307174 (1) was identified as a screening lead for the vasopressin V1a receptor (IC50 45 nM at the human V1a receptor) based on molecular similarity to ketoconazole (2), a known antagonist of the luteinizing hormone releasing hormone receptor. Structure-activity relationships for the series were explored to optimize receptor affinity and pharmacokinetic properties, resulting in compounds with Ki values < 1 nM and brain levels after oral dosing ~100-fold higher than receptor affinities. PMID:17234419

  7. Endothelin antagonists: new bullets against lung injury?

    PubMed

    Leeman, Marc

    2005-06-01

    Acute lung injury is a syndrome of inflammation and of increased permeability of the blood-gas barrier. Endothelins are thought to exert proinflammatory effects. Kuklin and colleagues show that the endothelin receptor antagonist tezosentan reduces pulmonary edema in endotoxemic sheep, in parallel with a prevention of protein kinase C-alpha activation. In turn, the level of some cytokines increased after tezosentan treatment. Whether these contrasting effects of endothelin blockade on inflammatory mechanisms have clinical relevance and whether these agents might benefit patients with acute lung injury is unknown.

  8. Mineralocorticoid receptor antagonists and endothelial function

    PubMed Central

    Maron, Bradley A.; Leopold, Jane A.

    2010-01-01

    Hyperaldosteronism has been associated with endothelial dysfunction and impaired vascular reactivity in patients with hypertension or congestive heart failure. The mineralocorticoid receptor (MR) antagonists spironolactone and eplerenone have been shown to reduce morbidity and mortality, in part, by ameliorating the adverse effects of aldosterone on vascular function. Although spironolactone and eplerenone are increasingly utilized in patients with cardiovascular disease, widespread clinical use is limited by the development of gynecomastia with spironolactone and hyperkalemia with both agents. This suggests that the development of newer agents with favorable side effect profiles is warranted. PMID:18729003

  9. Elucidating the `Jekyll and Hyde' Nature of PXR: The Case for Discovering Antagonists or Allosteric Antagonists

    PubMed Central

    Biswas, Arunima; Mani, Sridhar; Redinbo, Matthew R.; Krasowski, Matthew D.; Li, Hao; Ekins, Sean

    2010-01-01

    The pregnane X receptor belongs to the nuclear hormone receptor superfamily and is involved in the transcriptional control of numerous genes. It was originally thought that it was a xenobiotic sensor controlling detoxification pathways. Recent studies have shown an increasingly important role in inflammation and cancer, supporting its function in abrogating tissue damage. PXR orthologs and PXR-like pathways have been identified in several non-mammalian species which corroborate a conserved role for PXR in cellular detoxification. In summary, PXR has a multiplicity of roles in vivo and is being revealed as behaving like a “Jekyll and Hyde” nuclear hormone receptor. The importance of this review is to elucidate the need for discovery of antagonists of PXR to further probe its biology and therapeutic applications. Although several PXR agonists are already reported, virtually nothing is known about PXR antagonists. Here, we propose the development of PXR antagonists through chemical, genetic and molecular modeling approaches. Based on this review it will be clear that antagonists of PXR and PXR-like pathways will have widespread utility in PXR biology and therapeutics. PMID:19415465

  10. Sexually Antagonistic Selection in Human Male Homosexuality

    PubMed Central

    Camperio Ciani, Andrea; Cermelli, Paolo; Zanzotto, Giovanni

    2008-01-01

    Several lines of evidence indicate the existence of genetic factors influencing male homosexuality and bisexuality. In spite of its relatively low frequency, the stable permanence in all human populations of this apparently detrimental trait constitutes a puzzling ‘Darwinian paradox’. Furthermore, several studies have pointed out relevant asymmetries in the distribution of both male homosexuality and of female fecundity in the parental lines of homosexual vs. heterosexual males. A number of hypotheses have attempted to give an evolutionary explanation for the long-standing persistence of this trait, and for its asymmetric distribution in family lines; however a satisfactory understanding of the population genetics of male homosexuality is lacking at present. We perform a systematic mathematical analysis of the propagation and equilibrium of the putative genetic factors for male homosexuality in the population, based on the selection equation for one or two diallelic loci and Bayesian statistics for pedigree investigation. We show that only the two-locus genetic model with at least one locus on the X chromosome, and in which gene expression is sexually antagonistic (increasing female fitness but decreasing male fitness), accounts for all known empirical data. Our results help clarify the basic evolutionary dynamics of male homosexuality, establishing this as a clearly ascertained sexually antagonistic human trait. PMID:18560521

  11. Sexually antagonistic selection in human male homosexuality.

    PubMed

    Camperio Ciani, Andrea; Cermelli, Paolo; Zanzotto, Giovanni

    2008-06-18

    Several lines of evidence indicate the existence of genetic factors influencing male homosexuality and bisexuality. In spite of its relatively low frequency, the stable permanence in all human populations of this apparently detrimental trait constitutes a puzzling 'Darwinian paradox'. Furthermore, several studies have pointed out relevant asymmetries in the distribution of both male homosexuality and of female fecundity in the parental lines of homosexual vs. heterosexual males. A number of hypotheses have attempted to give an evolutionary explanation for the long-standing persistence of this trait, and for its asymmetric distribution in family lines; however a satisfactory understanding of the population genetics of male homosexuality is lacking at present. We perform a systematic mathematical analysis of the propagation and equilibrium of the putative genetic factors for male homosexuality in the population, based on the selection equation for one or two diallelic loci and Bayesian statistics for pedigree investigation. We show that only the two-locus genetic model with at least one locus on the X chromosome, and in which gene expression is sexually antagonistic (increasing female fitness but decreasing male fitness), accounts for all known empirical data. Our results help clarify the basic evolutionary dynamics of male homosexuality, establishing this as a clearly ascertained sexually antagonistic human trait.

  12. Antagonistic coevolution between quantitative and Mendelian traits.

    PubMed

    Yamamichi, Masato; Ellner, Stephen P

    2016-03-30

    Coevolution is relentlessly creating and maintaining biodiversity and therefore has been a central topic in evolutionary biology. Previous theoretical studies have mostly considered coevolution between genetically symmetric traits (i.e. coevolution between two continuous quantitative traits or two discrete Mendelian traits). However, recent empirical evidence indicates that coevolution can occur between genetically asymmetric traits (e.g. between quantitative and Mendelian traits). We examine consequences of antagonistic coevolution mediated by a quantitative predator trait and a Mendelian prey trait, such that predation is more intense with decreased phenotypic distance between their traits (phenotype matching). This antagonistic coevolution produces a complex pattern of bifurcations with bistability (initial state dependence) in a two-dimensional model for trait coevolution. Furthermore, with eco-evolutionary dynamics (so that the trait evolution affects predator-prey population dynamics), we find that coevolution can cause rich dynamics including anti-phase cycles, in-phase cycles, chaotic dynamics and deterministic predator extinction. Predator extinction is more likely to occur when the prey trait exhibits complete dominance rather than semidominance and when the predator trait evolves very rapidly. Our study illustrates how recognizing the genetic architectures of interacting ecological traits can be essential for understanding the population and evolutionary dynamics of coevolving species. © 2016 The Author(s).

  13. Antagonistic coevolution between quantitative and Mendelian traits

    PubMed Central

    Ellner, Stephen P.

    2016-01-01

    Coevolution is relentlessly creating and maintaining biodiversity and therefore has been a central topic in evolutionary biology. Previous theoretical studies have mostly considered coevolution between genetically symmetric traits (i.e. coevolution between two continuous quantitative traits or two discrete Mendelian traits). However, recent empirical evidence indicates that coevolution can occur between genetically asymmetric traits (e.g. between quantitative and Mendelian traits). We examine consequences of antagonistic coevolution mediated by a quantitative predator trait and a Mendelian prey trait, such that predation is more intense with decreased phenotypic distance between their traits (phenotype matching). This antagonistic coevolution produces a complex pattern of bifurcations with bistability (initial state dependence) in a two-dimensional model for trait coevolution. Furthermore, with eco-evolutionary dynamics (so that the trait evolution affects predator–prey population dynamics), we find that coevolution can cause rich dynamics including anti-phase cycles, in-phase cycles, chaotic dynamics and deterministic predator extinction. Predator extinction is more likely to occur when the prey trait exhibits complete dominance rather than semidominance and when the predator trait evolves very rapidly. Our study illustrates how recognizing the genetic architectures of interacting ecological traits can be essential for understanding the population and evolutionary dynamics of coevolving species. PMID:27009218

  14. D-Cycloserine: Agonist turned antagonist.

    PubMed

    Lanthorn, T H

    1994-10-01

    D-Cycloserine can enhance activation of the NMDA receptor complex and could enhance the induction of long-term potentiation (LTP). In animals and humans, D-cycloserine can enhance performance in learning and memory tasks. This enhancing effect can disappear during repeated administration. The enhancing effects are also lost when higher doses are used, and replaced by behavioral and biochemical effects like those produced by NMDA antagonists. It has been reported that NMDA agonists, applied before or after tetanic stimulation, can block the induction of LTP. This may be the result of feedback inhibition of second messenger pathways stimulated by receptor activation. This may explain the antagonist-like effects of glycine partial agonists like D-cycloserine. In clinical trials of D-cycloserine in age-associated memory impairment (AAMI) and Alzheimer's disease, chronic treatment provided few positive effects on learning and memory. This may be due to inhibition of second messenger pathways following chronic stimulation of the receptor complex.

  15. Hypocretin antagonists in insomnia treatment and beyond.

    PubMed

    Ruoff, Chad; Cao, Michelle; Guilleminault, Christian

    2011-01-01

    Hypocretin neuropeptides have been shown to regulate transitions between wakefulness and sleep through stabilization of sleep promoting GABAergic and wake promoting cholinergic/monoaminergic neural pathways. Hypocretin also influences other physiologic processes such as metabolism, appetite, learning and memory, reward and addiction, and ventilatory drive. The discovery of hypocretin and its effect upon the sleep-wake cycle has led to the development of a new class of pharmacologic agents that antagonize the physiologic effects of hypocretin (i.e. hypocretin antagonists). Further investigation of these agents may lead to novel therapies for insomnia without the side-effect profile of currently available hypnotics (e.g. impaired cognition, confusional arousals, and motor balance difficulties). However, antagonizing a system that regulates the sleep-wake cycle while also influencing non-sleep physiologic processes may create an entirely different but equally concerning side-effect profile such as transient loss of muscle tone (i.e. cataplexy) and a dampened respiratory drive. In this review, we will discuss the discovery of hypocretin and its receptors, hypocretin and the sleep-wake cycle, hypocretin antagonists in the treatment of insomnia, and other implicated functions of the hypocretin system.

  16. The antiatherogenic potential of calcium antagonists.

    PubMed

    Weinstein, D B

    1988-01-01

    Atherosclerosis is an arterial disease characterized by focal accumulation of collagen, elastin, lipids, and calcium at sites associated with macrophage infiltration and altered smooth muscle metabolic function. Studies in several types of animal models, especially cholesterol-fed rabbits, have shown that calcium competitors, calcium chelators, anticalcifying agents, and calcium channel blockers can reduce the accumulation of atherogenic lesion components and thus apparently decrease the progression of lesions. Although there are some conflicting data in the animal model studies using calcium channel antagonists, as a result of differences in experimental designs, it is now apparent that several classes of calcium channel blockers inhibit the progression of early arterial lesions induced by cholesterol feeding. The dihydropyridine calcium channel blockers appear to be more potent antiatherosclerotic agents than other classes of calcium channel antagonists. Several mechanisms involving regulation of endothelial cell, smooth muscle cell, and macrophage metabolic functions may be responsible for the calcium channel blocker effects on early lesion progression. For example, recent studies in cell culture model systems suggest that calcium channel blockers may significantly alter activities that regulate lipoprotein-derived cholesterol accumulation by cells. Some of these activities are independent of calcium flux across voltage-operated calcium channels. Thus, calcium channel blockers may reduce the progression of atherogenic lesions by a combination of decreasing calcium accumulation within arterial wall cells and by altering calcium-independent metabolic activities.

  17. Zebrafish phenotypic screen identifies novel Notch antagonists.

    PubMed

    Velaithan, Vithya; Okuda, Kazuhide Shaun; Ng, Mei Fong; Samat, Norazwana; Leong, Sze Wei; Faudzi, Siti Munirah Mohd; Abas, Faridah; Shaari, Khozirah; Cheong, Sok Ching; Tan, Pei Jean; Patel, Vyomesh

    2017-04-01

    Zebrafish represents a powerful in vivo model for phenotype-based drug discovery to identify clinically relevant small molecules. By utilizing this model, we evaluated natural product derived compounds that could potentially modulate Notch signaling that is important in both zebrafish embryogenesis and pathogenic in human cancers. A total of 234 compounds were screened using zebrafish embryos and 3 were identified to be conferring phenotypic alterations similar to embryos treated with known Notch inhibitors. Subsequent secondary screens using HEK293T cells overexpressing truncated Notch1 (HEK293TΔE) identified 2 compounds, EDD3 and 3H4MB, to be potential Notch antagonists. Both compounds reduced protein expression of NOTCH1, Notch intracellular domain (NICD) and hairy and enhancer of split-1 (HES1) in HEK293TΔE and downregulated Notch target genes. Importantly, EDD3 treatment of human oral cancer cell lines demonstrated reduction of Notch target proteins and genes. EDD3 also inhibited proliferation and induced G0/G1 cell cycle arrest of ORL-150 cells through inducing p27(KIP1). Our data demonstrates the utility of the zebrafish phenotypic screen and identifying EDD3 as a promising Notch antagonist for further development as a novel therapeutic agent.

  18. Rational discovery of novel nuclear hormone receptor antagonists

    NASA Astrophysics Data System (ADS)

    Schapira, Matthieu; Raaka, Bruce M.; Samuels, Herbert H.; Abagyan, Ruben

    2000-02-01

    Nuclear hormone receptors (NRs) are potential targets for therapeutic approaches to many clinical conditions, including cancer, diabetes, and neurological diseases. The crystal structure of the ligand binding domain of agonist-bound NRs enables the design of compounds with agonist activity. However, with the exception of the human estrogen receptor-, the lack of antagonist-bound "inactive" receptor structures hinders the rational design of receptor antagonists. In this study, we present a strategy for designing such antagonists. We constructed a model of the inactive conformation of human retinoic acid receptor- by using information derived from antagonist-bound estrogen receptor-α and applied a computer-based virtual screening algorithm to identify retinoic acid receptor antagonists. Thus, the currently available crystal structures of NRs may be used for the rational design of antagonists, which could lead to the development of novel drugs for a variety of diseases.

  19. Antioxidant effects of calcium antagonists in rat brain homogenates.

    PubMed

    Yao, K; Ina, Y; Nagashima, K; Ohmori, K; Ohno, T

    2000-06-01

    We studied the antioxidant activities of calcium antagonists against autoxidation in rat brain homogenates. The homogenates were incubated for 30 min at 37 degrees C with or without a calcium antagonist and subsequently assayed for lipid peroxide content. Percent inhibition of the lipid peroxidation was used as an index of the antioxidant effect. Dihydropyridine calcium antagonists exhibited concentration-dependent (3-300 micromol/l) inhibitory effects against lipid peroxidation. The relative order of antioxidant potency and associated IC50 values (micromol/l) of the calcium antagonists for inhibition of the lipid peroxidation were as follows: nifedipine (51.5)>barnidipine (58.6)>benidipine (71.2)>nicardipine (129.3)>amlodipine (135.5)>nilvadipine (167.3)>nitrendipine (252.1)> diltiazem (>300)=verapamil (>300). These results suggest that some dihydropyridine calcium antagonists show antioxidant properties. The antioxidant effects of the calcium antagonists may contribute to their pharmacological actions.

  20. Phenylacetamides as selective alpha-1A adrenergic receptor antagonists.

    PubMed

    Patane, M A; DiPardo, R M; Newton, R C; Price, R P; Broten, T P; Chang, R S; Ransom, R W; Di Salvo, J; Nagarathnam, D; Forray, C; Gluchowski, C; Bock, M G

    2000-08-07

    A novel class of potent and selective alpha-1a receptor antagonists has been identified. The structures of these antagonists were derived from truncating the 4-aryl dihydropyridine subunit present in known alpha-1a antagonists. The design principles which led to the discovery of substituted phenylacetamides, the synthesis and SAR of key analogues, and the results of select in vitro and in vivo studies are described.

  1. Synthesis of actively adjustable springs by antagonistic redundant actuation

    NASA Technical Reports Server (NTRS)

    Yi, Byung-Ju; Freeman, Robert A.

    1992-01-01

    A methodology for active spring generation is presented based on antagonistic redundant actuation. Antagonistic properties are characterized using an effective system stiffness. 'Antagonistic stiffness' is generated by preloading a closed-chain (parallel) linkage system. Internal load distribution is investigated along with the necessary conditions for spring synthesis. The performance and stability of a proposed active spring are shown by simulation, and applications are discussed.

  2. Mutually-antagonistic interactions in baseball networks

    NASA Astrophysics Data System (ADS)

    Saavedra, Serguei; Powers, Scott; McCotter, Trent; Porter, Mason A.; Mucha, Peter J.

    2010-03-01

    We formulate the head-to-head matchups between Major League Baseball pitchers and batters from 1954 to 2008 as a bipartite network of mutually-antagonistic interactions. We consider both the full network and single-season networks, which exhibit structural changes over time. We find interesting structure in the networks and examine their sensitivity to baseball’s rule changes. We then study a biased random walk on the matchup networks as a simple and transparent way to (1) compare the performance of players who competed under different conditions and (2) include information about which particular players a given player has faced. We find that a player’s position in the network does not correlate with his placement in the random walker ranking. However, network position does have a substantial effect on the robustness of ranking placement to changes in head-to-head matchups.

  3. Drug effects: agonistic and antagonistic processes.

    PubMed

    Flaten, Magne Arve

    2009-12-01

    The research presented here has shown that tolerance to drugs can be accelerated by conditioning processes. Placebo effects may be considered the opposite of tolerance, and we have shown that placebo effects may be objectively recorded by physiological measures (electromyography, skin conductance responses, and event-related potentials), as well as by behavioral and subjective methods. The placebo response, or more precisely, the expectation of drug effects, can add to the effect of the drug. Drug antagonistic expectations can also reverse the effect of the drug. There is some evidence that placebo effects are strongest when expectations are reinforced by administration of an active drug. Expectations have graded effects and may affect symptoms to a smaller or larger degree. Although drug effects can be considered stimuli, the investigation of the role of classical conditioning in drug use and drug effects involves special issues that must be carefully considered.

  4. Antagonists of IAP proteins as cancer therapeutics.

    PubMed

    Dynek, Jasmin N; Vucic, Domagoj

    2013-05-28

    Inhibitor of apoptosis (IAP) proteins play pivotal roles in cellular survival by blocking apoptosis, modulating signal transduction, and affecting cellular proliferation. Through their interactions with inducers and effectors of apoptosis IAP proteins can effectively suppress apoptosis triggered by diverse stimuli including death receptor signaling, irradiation, chemotherapeutic agents, or growth factor withdrawal. Evasion of apoptosis, in part due to the action of IAP proteins, enhances resistance of cancer cells to treatment with chemotherapeutic agents and contributes to tumor progression. Additionally, IAP genes are known to be subject to amplification, mutation, and chromosomal translocation in human malignancies and autoimmune diseases. In this review we will discuss the role of IAP proteins in cancer and the development of antagonists targeting IAP proteins for cancer treatment.

  5. Pervasive antagonistic interactions among hybrid incompatibility loci.

    PubMed

    Guerrero, Rafael F; Muir, Christopher D; Josway, Sarah; Moyle, Leonie C

    2017-06-01

    Species barriers, expressed as hybrid inviability and sterility, are often due to epistatic interactions between divergent loci from two lineages. Theoretical models indicate that the strength, direction, and complexity of these genetic interactions can strongly affect the expression of interspecific reproductive isolation and the rates at which new species evolve. Nonetheless, empirical analyses have not quantified the frequency with which loci are involved in interactions affecting hybrid fitness, and whether these loci predominantly interact synergistically or antagonistically, or preferentially involve loci that have strong individual effects on hybrid fitness. We systematically examined the prevalence of interactions between pairs of short chromosomal regions from one species (Solanum habrochaites) co-introgressed into a heterospecific genetic background (Solanum lycopersicum), using lines containing pairwise combinations of 15 chromosomal segments from S. habrochaites in the background of S. lycopersicum (i.e., 95 double introgression lines). We compared the strength of hybrid incompatibility (either pollen sterility or seed sterility) expressed in each double introgression line to the expected additive effect of its two component single introgressions. We found that epistasis was common among co-introgressed regions. Interactions for hybrid dysfunction were substantially more prevalent in pollen fertility compared to seed fertility phenotypes, and were overwhelmingly antagonistic (i.e., double hybrids were less unfit than expected from additive single introgression effects). This pervasive antagonism is expected to attenuate the rate at which hybrid infertility accumulates among lineages over time (i.e., giving diminishing returns as more reproductive isolation loci accumulate), as well as decouple patterns of accumulation of sterility loci and hybrid incompatibility phenotypes. This decoupling effect might explain observed differences between pollen and

  6. Activation of serotonin 3 receptors changes in vivo auditory responses in the mouse inferior colliculus

    PubMed Central

    Bohorquez, Alexander; Hurley, Laura M.

    2009-01-01

    Metabotropic serotonin receptors such as 5-HT1A and 5-HT1B receptors shape the level, selectivity, and timing of auditory responses in the inferior colliculus (IC). Less is known about the effects of ionotropic 5-HT3 receptors, which are cation channels that depolarize neurons. In the current study, the influence of the 5-HT3 receptor on auditory responses in vivo was explored by locally iontophoresing a 5-HT3 receptor agonist and antagonists onto single neurons recorded extracellularly in mice. Three main findings emerge from these experiments. First, activation of the 5-HT3 receptor can either facilitate or suppress auditory responses, but response suppressions are not consistent with 5-HT3 effects on presynaptic GABAergic neurons. Both response facilitations and suppressions are less pronounced in neurons with high precision in response latency, suggesting functional differences in the role of receptor activation for different classes of neuron. Finally, the effects of 5-HT3 activation vary across repetition rate within a subset of single neurons, suggesting that the influence of receptor activation sometimes varies with the level of activity. These findings contribute to the view of the 5-HT3 receptor as an important component of the serotonergic infrastructure in the IC, with effects that are complex and neuron- selective. PMID:19236912

  7. Pharmacological and clinical importance of narcotic antagonists and mixed antagonists — use in cardiology

    PubMed Central

    Coltart, D. John; Malcolm, Alasdair D.

    1979-01-01

    1 The treatment of pain of cardiac origin requires a knowledge of the haemodynamic action of the analgesic agents used. 2 The haemodynamic effects of morphine, diamorphine, pavaveretum, pethidine and pentazocine are reviewed. 3 Clinical experience with the new antagonist analgesic buprenorphine is reported. 4 These studies indicate that buprenorphine may be the agent of choice for the relief of severe pain in patients with unstable circulation. PMID:465292

  8. Antagonistic and Bargaining Games in Optimal Marketing Decisions

    ERIC Educational Resources Information Center

    Lipovetsky, S.

    2007-01-01

    Game theory approaches to find optimal marketing decisions are considered. Antagonistic games with and without complete information, and non-antagonistic games techniques are applied to paired comparison, ranking, or rating data for a firm and its competitors in the market. Mix strategy, equilibrium in bi-matrix games, bargaining models with…

  9. Antagonistic and Bargaining Games in Optimal Marketing Decisions

    ERIC Educational Resources Information Center

    Lipovetsky, S.

    2007-01-01

    Game theory approaches to find optimal marketing decisions are considered. Antagonistic games with and without complete information, and non-antagonistic games techniques are applied to paired comparison, ranking, or rating data for a firm and its competitors in the market. Mix strategy, equilibrium in bi-matrix games, bargaining models with…

  10. [Effects of PAF antagonists in experimental models. Therapeutical perspectives].

    PubMed

    Desquand, S

    1993-01-01

    The discovery, during the last ten years, of Platelet Activating Factor (PAF) antagonists with different frameworks, but efficient on platelets tests, led the authors to study their activity in vivo against PAF-induced effects. These antagonists inhibit, with various potencies, the effects of PAF administration such as hypotension and bronchoconstriction in different animal species. Since PAF is assumed to play a central role in many diseases, effects of its antagonists have been studied in experimentally induced pathologies and in few clinical studies. We have been particularly interested in their effects on the first manifestation of asthma which is hypersensitivity. This manifestation is experimentally reproduced by anaphylactic bronchoconstriction, usually in the guinea-pig. Our results showed that different sensitization procedures may determine the relative efficiency of a PAF antagonist on subsequent antigen challenge. Indeed, the booster injection of antigen to a pre-sensitized animal could account for the refractoriness of anaphylactic bronchoconstriction to PAF antagonists. This booster injection mimics the clinical situation of atopic patients repeatedly exposed to allergen. Thus, it seems that immediate hypersensitivity could not be treated by the unique administration of a PAF antagonist. However, those antagonists may have more benefit in the clinical management of the late phase of asthma and of hyperreactivity and could thus provide anti-asthmatic drugs. PAF antagonists may have also therapeutical effects in septic shock, in myocardial ischemia and cardiac rhythm disturbances, in brain damage following cerebral ischemia and neurological trauma, in gastric and intestinal damages or in some inflammatory reactions.

  11. Microbial antagonists of Verticillium dahliae colonize cotton root system

    USDA-ARS?s Scientific Manuscript database

    Verticillium wilt remains one of the most severe diseases affecting cotton production in Uzbekistan. We are investigating microbial antagonist to control this pathogen. To this end, we have identified several antagonists of Verticillium dahliae (Bacillus sp. 234, Bacillus sp. 3, Streptomyces roseofl...

  12. Identification of a sulfonamide series of CCR2 antagonists.

    PubMed

    Peace, Simon; Philp, Joanne; Brooks, Carl; Piercy, Val; Moores, Kitty; Smethurst, Chris; Watson, Steve; Gaines, Simon; Zippoli, Mara; Mookherjee, Claudette; Ife, Robert

    2010-07-01

    A series of sulfonamide CCR2 antagonists was identified by high-throughput screening. Management of molecular weight and physical properties, in particular moderation of lipophilicity and study of pK(a), yielded highly potent CCR2 antagonists exhibiting good pharmacokinetic properties and improved potency in the presence of human plasma.

  13. Third Generation Mineralocorticoid Receptor Antagonists; Why We Need a Fourth

    PubMed Central

    Gomez-Sanchez, Elise

    2015-01-01

    The first mineralocorticoid receptor (MR) antagonist, spironolactone, was developed almost 60 years ago to treat primary aldosteronism and pathological edema. Its use waned in part due to its lack of selectivity. Subsequently knowledge of the scope of MR function was expanded along with clinical evidence of the therapeutic importance of MR antagonists to prevent the ravages of inappropriate MR activation. Forty-two years elapsed between the first and MR-selective second generation of MR antagonists. Fifteen years later, despite serious shortcomings of the existing antagonists, a third generation antagonist has yet to be marketed. Progress has been slowed by the lack of appreciation of the large variety of cell types that express the MR and its diverse cell-type-specific actions, as well as its uniquely complex interactions actions at the molecular level. New MR antagonists should preferentially target the inflammatory and fibrotic effects of MR and perhaps its excitatory effects on sympathetic nervous system, but not the renal tubular epithelium or neurons of the cortex and hippocampus. This review briefly describes efforts to develop a third generation MR antagonist and why fourth generation antagonists and selective agonists based on structural determinants of tissue and ligand-specific MR activation should be contemplated. PMID:26466326

  14. Early gonadotropin-releasing hormone antagonist start improves follicular synchronization and pregnancy outcome as compared to the conventional antagonist protocol.

    PubMed

    Park, Chan Woo; Hwang, Yu Im; Koo, Hwa Seon; Kang, Inn Soo; Yang, Kwang Moon; Song, In Ok

    2014-12-01

    To assess whether an early GnRH antagonist start leads to better follicular synchronization and an improved clinical pregnancy rate (CPR). A retrospective cohort study. A total of 218 infertile women who underwent IVF between January 2011 and February 2013. The initial cohort (Cohort I) that underwent IVF between January 2011 and March 2012 included a total of 68 attempted IVF cycles. Thirty-four cycles were treated with the conventional GnRH antagonist protocol, and 34 cycles with an early GnRH antagonist start protocol. The second cohort (Cohort II) that underwent IVF between June 2012 and February 2013 included a total of 150 embryo-transfer (ET) cycles. Forty-three cycles were treated with the conventional GnRH antagonist protocol, 34 cycles with the modified early GnRH antagonist start protocol using highly purified human menopause gonadotropin and an addition of GnRH agonist to the luteal phase support, and 73 cycles with the GnRH agonist long protocol. The analysis of Cohort I showed that the number of mature oocytes retrieved was significantly higher in the early GnRH antagonist start cycles than in the conventional antagonist cycles (11.9 vs. 8.2, p=0.04). The analysis of Cohort II revealed higher but non-significant CPR/ET in the modified early GnRH antagonist start cycles (41.2%) than in the conventional antagonist cycles (30.2%), which was comparable to that of the GnRH agonist long protocol cycles (39.7%). The modified early antagonist start protocol may improve the mature oocyte yield, possibly via enhanced follicular synchronization, while resulting in superior CPR as compared to the conventional antagonist protocol, which needs to be studied further in prospective randomized controlled trials.

  15. Prostanoid receptor antagonists: development strategies and therapeutic applications

    PubMed Central

    Jones, RL; Giembycz, MA; Woodward, DF

    2009-01-01

    Identification of the primary products of cyclo-oxygenase (COX)/prostaglandin synthase(s), which occurred between 1958 and 1976, was followed by a classification system for prostanoid receptors (DP, EP1, EP2 …) based mainly on the pharmacological actions of natural and synthetic agonists and a few antagonists. The design of potent selective antagonists was rapid for certain prostanoid receptors (EP1, TP), slow for others (FP, IP) and has yet to be achieved in certain cases (EP2). While some antagonists are structurally related to the natural agonist, most recent compounds are ‘non-prostanoid’ (often acyl-sulphonamides) and have emerged from high-throughput screening of compound libraries, made possible by the development of (functional) assays involving single recombinant prostanoid receptors. Selective antagonists have been crucial to defining the roles of PGD2 (acting on DP1 and DP2 receptors) and PGE2 (on EP1 and EP4 receptors) in various inflammatory conditions; there are clear opportunities for therapeutic intervention. The vast endeavour on TP (thromboxane) antagonists is considered in relation to their limited pharmaceutical success in the cardiovascular area. Correspondingly, the clinical utility of IP (prostacyclin) antagonists is assessed in relation to the cloud hanging over the long-term safety of selective COX-2 inhibitors. Aspirin apart, COX inhibitors broadly suppress all prostanoid pathways, while high selectivity has been a major goal in receptor antagonist development; more targeted therapy may require an intermediate position with defined antagonist selectivity profiles. This review is intended to provide overviews of each antagonist class (including prostamide antagonists), covering major development strategies and current and potential clinical usage. PMID:19624532

  16. Antagonistic neural networks underlying differentiated leadership roles

    PubMed Central

    Boyatzis, Richard E.; Rochford, Kylie; Jack, Anthony I.

    2014-01-01

    The emergence of two distinct leadership roles, the task leader and the socio-emotional leader, has been documented in the leadership literature since the 1950s. Recent research in neuroscience suggests that the division between task-oriented and socio-emotional-oriented roles derives from a fundamental feature of our neurobiology: an antagonistic relationship between two large-scale cortical networks – the task-positive network (TPN) and the default mode network (DMN). Neural activity in TPN tends to inhibit activity in the DMN, and vice versa. The TPN is important for problem solving, focusing of attention, making decisions, and control of action. The DMN plays a central role in emotional self-awareness, social cognition, and ethical decision making. It is also strongly linked to creativity and openness to new ideas. Because activation of the TPN tends to suppress activity in the DMN, an over-emphasis on task-oriented leadership may prove deleterious to social and emotional aspects of leadership. Similarly, an overemphasis on the DMN would result in difficulty focusing attention, making decisions, and solving known problems. In this paper, we will review major streams of theory and research on leadership roles in the context of recent findings from neuroscience and psychology. We conclude by suggesting that emerging research challenges the assumption that role differentiation is both natural and necessary, in particular when openness to new ideas, people, emotions, and ethical concerns are important to success. PMID:24624074

  17. Autoimmune encephalomyelitis ameliorated by AMPA antagonists.

    PubMed

    Smith, T; Groom, A; Zhu, B; Turski, L

    2000-01-01

    Multiple sclerosis is an immune-mediated disorder of the central nervous system leading to progressive decline of motor and sensory functions and permanent disability. The therapy of multiple sclerosis is only partially effective, despite anti-inflammatory, immunosuppresive and immunomodulatory measures. White matter inflammation and loss of myelin, the pathological hallmarks of multiple sclerosis, are thought to determine disease severity. Experimental autoimmune encephalomyelitis reproduces the features of multiple sclerosis in rodents and in nonhuman primates. The dominant early clinical symptom of acute autoimmune encephalomyelitis is progressive ascending muscle weakness. However, demyelination may not be profound and its extent may not correlate with severity of neurological decline, indicating that targets unrelated to myelin or oligodendrocytes may contribute to the pathogenesis of acute autoimmune encephalomyelitis. Here we report that within the spinal cord in the course of autoimmune encephalomyelitis not only myelin but also neurons are subject to lymphocyte attack and may degenerate. Blockade of glutamate AMPA receptors ameliorated the neurological sequelae of autoimmune encephalomyelitis, indicating the potential for AMPA antagonists in the therapy of multiple sclerosis.

  18. Antagonists of alcohol inhibition of cell adhesion

    PubMed Central

    Wilkemeyer, Michael F.; Sebastian, Anita B.; Smith, Sherri A.; Charness, Michael E.

    2000-01-01

    Increasing evidence suggests that alcohols act within specific binding pockets of selective neural proteins; however, antagonists at these sites have not been identified. 1-Alcohols from methanol through 1-butanol inhibit with increasing potency the cell–cell adhesion mediated by the immunoglobulin cell adhesion molecule L1. An abrupt cutoff exists after 1-butanol, with 1-pentanol and higher 1-alcohols showing no effect. Here, we demonstrate surprisingly strict structural requirements for alcohol inhibition of cell–cell adhesion in L1-transfected NIH 3T3 fibroblasts and in NG108–15 neuroblastoma × glioma hybrid cells treated with BMP-7, an inducer of L1 and neural cell adhesion molecule. The target site discriminates the tertiary structure of straight-chain and branched-chain alcohols and appears to comprise both a hydrophobic binding site and an adjacent hydrophilic allosteric site. Modifications to the 2- and 3-carbon positions of 1-butanol increased potency, whereas modifications that restrict movement about the 4-carbon abolished activity. The effects of ethanol and 1-butanol on cell–cell adhesion were antagonized by 1-pentanol (IC50 = 715 μM) and 1-octanol (IC50 = 3.6 μM). Antagonism by 1-octanol was complete, reversible, and noncompetitive. 1-Octanol also antagonized ethanol inhibition of BMP-7 morphogenesis in NG108–15 cells. 1-Octanol and related compounds may prove useful in dissecting the role of altered cell adhesion in ethanol-induced injury of the nervous system. PMID:10725368

  19. Noradrenergic antagonists mitigate amphetamine-induced recovery.

    PubMed

    Hylin, M J; Brenneman, M M; Corwin, J V

    2017-09-15

    Brain injury, including that due to stroke, leaves individuals with cognitive deficits that can disrupt daily aspect of living. As of now there are few treatments that shown limited amounts of success in improving functional outcome. The use of stimulants such as amphetamine have shown some success in improving outcome following brain injury. While the pharmacological mechanisms for amphetamine are known; the specific processes responsible for improving behavioral outcome following injury remain unknown. Understanding these mechanisms can help to refine the use of amphetamine as a potential treatment or lead to the use of other methods that share the same pharmacological properties. One proposed mechanism is amphetamine's impact upon noradrenaline (NA). In the current, study noradrenergic antagonists were administered prior to amphetamine to pharmacologically block α- and β-adrenergic receptors. The results demonstrated that the blockade of these receptors disrupted amphetamines ability to induce recovery from hemispatial neglect using an established aspiration lesion model. This suggests that amphetamine's ability to ameliorate neglect deficits may be due in part to noradrenaline. These results further support the role of noradrenaline in functional recovery. Finally, the development of polytherapies and combined therapeutics, while promising, may need to consider the possibility that drug interactions can negate the effectiveness of treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. HIGH AFFINITY ACYLATING ANTAGONISTS FOR MUSCARINIC RECEPTORS

    PubMed Central

    Baumgold, Jesse; Karton, Yishai; Malka, Naftali; Jacobson, Kenneth A.

    2012-01-01

    Summary The muscarinic antagonists pirenzepine and telenzepine were derivitized as alkylamino derivatives at a site on the molecules corresponding to a region of bulk tolerance in receptor binding. The distal primary amino groups were coupled to the cross-linking reagent meta-phenylene diisothiocyanate, resulting in two isothiocyanate derivatives that were found to inhibit muscarinic receptors irreversibly and in a dose-dependent fashion. Preincubation of rat forebrain membranes with an isothiocyanate derivative followed by radioligand binding using [3H]N-methylscopolamine diminished the Bmax value, but did not affect the Kd value. The receptor binding site was not restored upon repeated washing, indicating that irreversible inhibition had occurred. IC50 values for the irreversible inhibition at rat forebrain muscarinic receptors were 0.15 nM and 0.19 nM, for derivatives of pirenzepine and telenzepine, respectively. The isothiocyanate derivative of pirenzepine was non-selective as an irreversible muscarinic inhibitor, and the corresponding derivative prepared from telenzepine was 5-fold selective for forebrain (mainly m1) vs. heart (m2) muscarinic receptors. PMID:1625525

  1. Adrenergic antagonists restrict replication of Legionella.

    PubMed

    Harrison, Christopher F; Kicka, Sébastien; Kranjc, Agata; Finsel, Ivo; Chiriano, Gianpaolo; Ouertatani-Sakouhi, Hajer; Soldati, Thierry; Scapozza, Leonardo; Hilbi, Hubert

    2015-07-01

    Legionella pneumophila is a facultative intracellular bacterium, which upon inhalation can cause a potentially fatal pneumonia termed Legionnaires' disease. The opportunistic pathogen grows in environmental amoebae and mammalian macrophages within a unique membrane-bound compartment, the 'Legionella-containing vacuole'. Bacteria are exposed to many environmental cues including small signalling molecules from eukaryotic cells. A number of pathogenic bacteria sense and respond to catecholamine hormones, such as adrenalin and noradrenalin, a process mediated via the QseBC two-component system in some bacteria. In this study, we examined the effect of adrenergic compounds on L. pneumophila, and discovered that the adrenergic receptor antagonists benoxathian, naftopidil, propranolol and labetalol, as well as the QseC sensor kinase inhibitor LED209, reduced the growth of L. pneumophila in broth or amoebae, while replication in macrophages was enhanced. Growth restriction was common to members of the genus Legionella and Mycobacterium, and was observed for L. pneumophila in the replicative but not stationary phase of the biphasic life cycle. Deletion of the L. pneumophila qseBC genes indicated that growth inhibition by adrenergics or LED209 is mediated only to a minor extent by this two-component system, implying the presence of other adrenergic sensing systems. This study identifies adrenergic molecules as novel inhibitors of extra- and intracellular growth of Legionella and reveals LED209 as a potential lead compound to combat infections with Legionella or Mycobacterium spp.

  2. Antagonistic interactions among coral-associated bacteria.

    PubMed

    Rypien, Krystal L; Ward, Jessica R; Azam, Farooq

    2010-01-01

    Reef-building corals are comprised of close associations between the coral animal, symbiotic zooxanthellae, and a diversity of associated microbes (including Bacteria, Archaea and Fungi). Together, these comprise the coral holobiont - a paradigm that emphasizes the potential contributions of each component to the overall function and health of the coral. Little is known about the ecology of the coral-associated microbial community and its hypothesized role in coral health. We explored bacteria-bacteria antagonism among 67 bacterial isolates from the scleractinian coral Montastrea annularis at two temperatures using Burkholder agar diffusion assays. A majority of isolates exhibited inhibitory activity (69.6% of isolates at 25 degrees C, 52.2% at 31 degrees C), with members of the gamma-proteobacteria (Vibrionales and Alteromonadales) being especially antagonistic. Elevated temperatures generally reduced levels of antagonism, although the effects were complex. Several potential pathogens were observed in the microbial community of apparently healthy corals, and 11.6% of isolates were able to inhibit the growth of the coral pathogen Vibrio shiloi at 25 degrees C. Overall, this study demonstrates that antagonism could be a structuring force in coral-associated microbial communities and may contribute to pathogenesis as well as disease resistance.

  3. Antagonists for acute oral cadmium chloride intoxication

    SciTech Connect

    Basinger, M.A.; Jones, M.M.; Holscher, M.A.; Vaughn, W.K.

    1988-01-01

    An examination has been carried out on the relative efficacy of a number of chelating agents when acting as antagonists for oral cadmium chloride intoxication in mice. The compounds were administered orally after the oral administration of cadmium chloride at 1 mmol/kg. Of the compounds examined, several were useful in terms of enhancing survival, but by far the most effective in both enhancing survival and leaving minimal residual levels of cadmium in the liver and the kidney, was meso-2,3-dimercaptosuccinic acid (DMSA). Several polyaminocarboxylic acids also enhanced survival. The most effective of these in reducing liver and kidney levels of cadmium were diethylenetriaminepentaacetic acid (DTPA), trans-1,2-diaminocyclohexane-N,N,N'N'-tetraacetic acid (CDTA), and triethylenetetraminehexaacetic acid (TTHA). D-Penicillamine (DPA) was found to promote survival but also led to kidney cadmium levels higher than those found in the controls. Sodium 2,3-dimercaptopropane-1-sulfonate (DMPS) was as effective in promoting survival as DMSA but left levels of cadmium in the kidney and liver that were approximately four times greater than those found with DMSA.

  4. Antagonistic neural networks underlying differentiated leadership roles.

    PubMed

    Boyatzis, Richard E; Rochford, Kylie; Jack, Anthony I

    2014-01-01

    The emergence of two distinct leadership roles, the task leader and the socio-emotional leader, has been documented in the leadership literature since the 1950s. Recent research in neuroscience suggests that the division between task-oriented and socio-emotional-oriented roles derives from a fundamental feature of our neurobiology: an antagonistic relationship between two large-scale cortical networks - the task-positive network (TPN) and the default mode network (DMN). Neural activity in TPN tends to inhibit activity in the DMN, and vice versa. The TPN is important for problem solving, focusing of attention, making decisions, and control of action. The DMN plays a central role in emotional self-awareness, social cognition, and ethical decision making. It is also strongly linked to creativity and openness to new ideas. Because activation of the TPN tends to suppress activity in the DMN, an over-emphasis on task-oriented leadership may prove deleterious to social and emotional aspects of leadership. Similarly, an overemphasis on the DMN would result in difficulty focusing attention, making decisions, and solving known problems. In this paper, we will review major streams of theory and research on leadership roles in the context of recent findings from neuroscience and psychology. We conclude by suggesting that emerging research challenges the assumption that role differentiation is both natural and necessary, in particular when openness to new ideas, people, emotions, and ethical concerns are important to success.

  5. TRPV1 Antagonist Suppresses Allergic Conjunctivitis in a Murine Model.

    PubMed

    Kwon, Ji Young; Lee, Hyun Soo; Joo, Choun-Ki

    2016-10-11

    To determine the immunologic functions of TRPA1 or TRPV1 in allergic conjunctivitis (AC). Mice were sensitized with ovalbumin (OVA), after which TRPA1 antagonist or TRPV1 antagonist was administered before topical OVA challenge. Expression of TRPV1 or TRPA1 in AC was examined by western blotting and multicolor immunofluorescence. Clinical signs, OVA-specific IgE, infiltration of inflammatory cells into conjunctivae (CJs), and Th2 cytokine in draining lymph nodes (LNs) were evaluated by microscopy, flow cytometry, and ELISA. TRPV1 expression was increased in CJs and LNs from AC mice, but TRPA1 expression was only increased in LNs. TRPV1 antagonist but not TRPA1 antagonist attenuated the clinical signs of AC and OVA-specific IgE in sera. TRPV1 antagonist furthermore inhibited the infiltration of inflammatory cells into CJ and the production of Th2 cytokines in LNs. TRPV1 antagonist but not TRPA1 antagonist may ameliorate AC by suppressing the Th2 response in LNs.

  6. Cannabinoid receptor antagonists: pharmacological opportunities, clinical experience, and translational prognosis.

    PubMed

    Janero, David R; Makriyannis, Alexandros

    2009-03-01

    The endogenous cannabinoid (CB) (endocannabinoid) signaling system is involved in a variety of (patho)physiological processes, primarily by virtue of natural, arachidonic acid-derived lipids (endocannabinoids) that activate G protein-coupled CB1 and CB2 receptors. A hyperactive endocannabinoid system appears to contribute to the etiology of several disease states that constitute significant global threats to human health. Consequently, mounting interest surrounds the design and profiling of receptor-targeted CB antagonists as pharmacotherapeutics that attenuate endocannabinoid transmission for salutary gain. Experimental and clinical evidence supports the therapeutic potential of CB1 receptor antagonists to treat overweight/obesity, obesity-related cardiometabolic disorders, and substance abuse. Laboratory data suggest that CB2 receptor antagonists might be effective immunomodulatory and, perhaps, anti-inflammatory drugs. One CB1 receptor antagonist/inverse agonist, rimonabant, has emerged as the first-in-class drug approved outside the United States for weight control. Select follow-on agents (taranabant, otenabant, surinabant, rosonabant, SLV-319, AVE1625, V24343) have also been studied in the clinic. However, rimonabant's market withdrawal in the European Union and suspension of rimonabant's, taranabant's, and otenabant's ongoing development programs have highlighted some adverse clinical side effects (especially nausea and psychiatric disturbances) of CB1 receptor antagonists/inverse agonists. Novel CB1 receptor ligands that are peripherally directed and/or exhibit neutral antagonism (the latter not affecting constitutive CB1 receptor signaling) may optimize the benefits of CB1 receptor antagonists while minimizing any risk. Indeed, CB1 receptor-neutral antagonists appear from preclinical data to offer efficacy comparable to or better than that of prototype CB1 receptor antagonists/inverse agonists, with less propensity to induce nausea. Continued

  7. Single exposure of dopamine D1 antagonist prevents and D2 antagonist attenuates methylphenidate effect

    PubMed Central

    Claussen, Catherine M; Witte, Lindsey J; Dafny, Nachum

    2015-01-01

    Methylphenidate (MPD) is a readily prescribed drug for the treatment of attention deficit hyperactivity disorder (ADHD) and moreover is used illicitly by youths for its cognitive-enhancing effects and recreation. MPD exposure in rodents elicits increased locomotor activity. Repetitive MPD exposure leads to further augmentation of their locomotor activity. This behavioral response is referred to as behavioral sensitization. Behavioral sensitization is used as an experimental marker for a drug’s ability to elicit dependence. There is evidence that dopamine (DA) is a key player in the acute and chronic MPD effect; however, the role of DA in the effects elicited by MPD is still debated. The objective of this study was to investigate the role of D1 and/or D2 DA receptors in the acute and chronic effect of MPD on locomotor activity. The study lasted for 12 consecutive days. Seven groups of male Sprague Dawley® rats were used. A single D1 or D2 antagonist was given before and after acute and chronic MPD administration. Single injection of D1 DA antagonist was able to significantly attenuate the locomotor activity when given prior to the initial MPD exposure and after repetitive MPD exposure, while the D2 DA antagonist partially attenuated the locomotor activity only when given before the second MPD exposure. The results show the role, at least in part, of the D1 DA receptor in the mechanism of behavioral sensitization, whereas the D2 DA receptor only partially modulates the response to acute and chronic MPD. PMID:27186140

  8. Multiple Targeting Approaches on Histamine H3 Receptor Antagonists

    PubMed Central

    Khanfar, Mohammad A.; Affini, Anna; Lutsenko, Kiril; Nikolic, Katarina; Butini, Stefania; Stark, Holger

    2016-01-01

    With the very recent market approval of pitolisant (Wakix®), the interest in clinical applications of novel multifunctional histamine H3 receptor antagonists has clearly increased. Since histamine H3 receptor antagonists in clinical development have been tested for a variety of different indications, the combination of pharmacological properties in one molecule for improved pharmacological effects and reduced unwanted side-effects is rationally based on the increasing knowledge on the complex neurotransmitter regulations. The polypharmacological approaches on histamine H3 receptor antagonists on different G-protein coupled receptors, transporters, enzymes as well as on NO-signaling mechanism are described, supported with some lead structures. PMID:27303254

  9. Intractable pneumococcal meningoencephalitis associated with a TNF-α antagonist.

    PubMed

    Kang, Seok-Jae; Kim, Hyun Young; Kim, Young Seo; Lee, Ha Neul; Kim, Hee Tae; Kim, Seung H

    2014-09-15

    A 34-year-old man was treated with a TNF-α antagonist for ankylosing spondylitis, and this subsequently developed a CNS infection. Magnetic resonance imaging showed diffuse subcortical white matter lesions. Streptococcus pneumoniae was cultured from the cerebrospinal fluid and blood. The patient died of multifocal widespread brain damage and subarachnoid hemorrhage, despite intensive antibacterial medication. Pneumococcal meningoencephalitis can occur in association with TNF-α antagonists. Clinicians should be aware of both the risk of fatal bacterial meningoencephalitis associated with TNF-α antagonists and the possibility of an unusual presentation of bacterial meningitis. Copyright © 2014. Published by Elsevier B.V.

  10. Multiple Targeting Approaches on Histamine H3 Receptor Antagonists.

    PubMed

    Khanfar, Mohammad A; Affini, Anna; Lutsenko, Kiril; Nikolic, Katarina; Butini, Stefania; Stark, Holger

    2016-01-01

    With the very recent market approval of pitolisant (Wakix®), the interest in clinical applications of novel multifunctional histamine H3 receptor antagonists has clearly increased. Since histamine H3 receptor antagonists in clinical development have been tested for a variety of different indications, the combination of pharmacological properties in one molecule for improved pharmacological effects and reduced unwanted side-effects is rationally based on the increasing knowledge on the complex neurotransmitter regulations. The polypharmacological approaches on histamine H3 receptor antagonists on different G-protein coupled receptors, transporters, enzymes as well as on NO-signaling mechanism are described, supported with some lead structures.

  11. New potential uroselective NO-donor alpha1-antagonists.

    PubMed

    Boschi, Donatella; Tron, Gian Cesare; Di Stilo, Antonella; Fruttero, Roberta; Gasco, Alberto; Poggesi, Elena; Motta, Gianni; Leonardi, Amedeo

    2003-08-14

    A recent uroselective alpha(1)-adrenoceptor antagonist, REC15/2739, has been joined with nitrooxy and furoxan NO-donor moieties to give new NO-donor alpha(1)-antagonists. All the compounds studied proved to be potent and selective ligands of human cloned alpha(1a)-receptor subtype. Derivatives 6 and 7 were able to relax the prostatic portion of rat vas deferens contracted by (-)-noradrenaline because of both their alpha(1A)-antagonist and their NO-donor properties.

  12. [Research progress of selective mGluR1 antagonists].

    PubMed

    Yang, Yi-lei; Sun, Wei; Peng, Cheng; Zhang, Xiao-ye; Yang, Xiao-hong

    2011-10-01

    As an important member of metabotropic glutamate receptors (mGluR), metabotropic glutamate receptor 1 (mGluR1) plays an important role in the signal transduction of central nervous system. Selective mGluR1 antagonists can block the signaling pathway activated by mGluR1 and exert a series of physiological actions including analgesia, antianxiety, antidepression, etc. Currently, the discovery and modification of selective mGluR1 antagonists have become a hot research focus. This paper reviews the structural catalogs of selective mGluR1 antagonists and their structure-activity relationships in the last decade.

  13. Pharmacological mechanisms of 5-HT₃ and tachykinin NK₁ receptor antagonism to prevent chemotherapy-induced nausea and vomiting.

    PubMed

    Rojas, Camilo; Slusher, Barbara S

    2012-06-05

    Nausea and vomiting are among the most common and distressing consequences of cytotoxic chemotherapies. Nausea and vomiting can be acute (0-24h) or delayed (24-72 h) after chemotherapy administration. The introduction of 5-HT(3) receptor antagonists in the 90s was a major advance in the prevention of acute emesis. These receptor antagonists exhibited similar control on acute emesis but had no effect on delayed emesis. These findings led to the hypothesis that serotonin plays a central role in the mechanism of acute emesis but a lesser role in the pathogenesis of delayed emesis. In contrast, delayed emesis has been largely associated with the activation of neurokinin 1 (NK(1)) receptors by substance P. However, in 2003, a new 5-HT(3) receptor antagonist was introduced into the market; unlike first generation 5-HT(3) receptor antagonists, palonosetron was found to be effective in preventing both acute and delayed chemotherapy induced nausea and vomiting. Recent mechanistic studies have shown that palonosetron, in contrast to first generation receptor antagonists, exhibits allosteric binding to the 5-HT(3) receptor, positive cooperativity, persistent inhibition of receptor function after the drug is removed and triggers 5-HT(3) receptor internalization. Further, in vitro and in vivo experiments have shown that palonosetron can inhibit substance P-mediated responses, presumably through its unique interactions with the 5-HT(3) receptor. It appears that the crossroads of acute and delayed emeses include interactions among the 5-HT(3) and NK(1) receptor neurotransmitter pathways and that inhibitions of these interactions lend the possibility of improved treatment that encompasses both acute and delayed emeses. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Anthropomorphic finger antagonistically actuated by SMA plates.

    PubMed

    Engeberg, Erik D; Dilibal, Savas; Vatani, Morteza; Choi, Jae-Won; Lavery, John

    2015-08-20

    Most robotic applications that contain shape memory alloy (SMA) actuators use the SMA in a linear or spring shape. In contrast, a novel robotic finger was designed in this paper using SMA plates that were thermomechanically trained to take the shape of a flexed human finger when Joule heated. This flexor actuator was placed in parallel with an extensor actuator that was designed to straighten when Joule heated. Thus, alternately heating and cooling the flexor and extensor actuators caused the finger to flex and extend. Three different NiTi based SMA plates were evaluated for their ability to apply forces to a rigid and compliant object. The best of these three SMAs was able to apply a maximum fingertip force of 9.01N on average. A 3D CAD model of a human finger was used to create a solid model for the mold of the finger covering skin. Using a 3D printer, inner and outer molds were fabricated to house the actuators and a position sensor, which were assembled using a multi-stage casting process. Next, a nonlinear antagonistic controller was developed using an outer position control loop with two inner MOSFET current control loops. Sine and square wave tracking experiments demonstrated minimal errors within the operational bounds of the finger. The ability of the finger to recover from unexpected disturbances was also shown along with the frequency response up to 7 rad s(-1). The closed loop bandwidth of the system was 6.4 rad s(-1) when operated intermittently and 1.8 rad s(-1) when operated continuously.