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Results for “Serotonin Antagonists”

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At least 19 recordsLinked to original sources
PubMed1982

Human EEG slow-wave sleep increased by a serotonin antagonist.

Serotonin has been held to play a necessary role in EEG slow-wave sleep. A central serotonin antagonist, known as FU 29-245, 200 mg, was taken nightly for 6 nights by 10 volunteers, mean age 59 years. Compared with baseline sleep the drug significantly increased the duration of slow-wave sleep, with a significant rebound decrease below baseline after withdrawal. The drug also caused fewer transitions into stage 1 and less time in stage 1 and less time in stage 2. There were significant tolerance effects by the fifth and sixth nights. No subjective effects were present.

Adult↗
PubMed1981

Action of selected serotonin antagonists on hyperthermia evoked by intracerebrally injected beta-endorphin.

Methergoline, an antagonist of cerebral serotonin receptors, has been shown to significantly reduce the rise in rectal temperature (Tre) produced by the intracerebral microinjection of beta-endorphin. In this study the role of serotonin in the increase in Tre elicited by beta-endorphin was further examined using three additional serotonin antagonists. beta-Endorphin was administered twice to rats using a crossover design in which half of the animals were first pretreated with the vehicle solution and half with the antagonist. Serotonin antagonists used were: methergoline, methysergide, cinanserin and cyproheptadine. Although methergoline did cause a marked reduction in the beta-endorphin-induced rise in Tre, neither methysergide, nor cinanserin, nor cyproheptadine produced a marked reduction in the hyperthermia. Since methergoline also interacts with the dopamine receptor, the effect of a dopamine antagonist, haloperidol, on the endorphin-evoked response was also examined. Haloperidol failed to attenuate the rise in Tre. The reason for the apparent discrepancy in the action of these serotonin antagonists is unclear. Further research may reveal distinct subpopulations of serotonin receptors at which these antagonists exert differential effects.

Animals↗
PubMedDate not supplied

The serotonin antagonist mianserin for treatment of serotonin reuptake inhibitor-induced sexual dysfunction in women: an open-label add-on study.

The aim of this study was to determine if the serotonin antagonist mianserin improves antidepressant-induced sexual dysfunction in women. The work was prompted by an earlier study of men by our team of researchers. The study population included 16 women aged 20-65 years undergoing treatment at a psychiatric outpatient clinic, who presented with sexual dysfunction subsequent to intake of a serotonin reuptake inhibitor (SRI) for depression. Sexual function (four domains) was evaluated by semistructured interviews before and after the administration of mianserin 15 mg/d for 3 weeks. The most prominent sexual dysfunction was anorgasmia. Clinically significant improvement was noted in all domains in two thirds of the patients, in most cases in the first or second week of treatment. None of the patients with panic disorder (PD) responded to mianserin, in contrast to those with affective disorder or obsessive compulsive disorder (OCD), indicating a possible relevance of the psychiatric diagnosis to mianserin effectiveness. There were no major adverse effects and no changes in the patients' stabilized psychiatric status. We conclude that mianserin is beneficial in reversing sexual function caused by SRI intake. Further large-scale, placebo-controlled studies are needed to confirm these findings.

Adult↗
PubMedDate not supplied

[The action of neurotransmitters and their antagonists on oocyte maturation. The action of serotonin antagonists on the in-vitro maturation of amphibian oocytes].

Serotonin antagonists (inmecarb hydrochloride and inmecarb methiodide) stimulate in vitro maturation of Bufo viridis and Xenopus laevis oocytes or potentiate the action of progesterone. In contrast to that, serotonin inhibits or blocks oocyte maturation stimulated by progesterone or serotonin antagonists. Sensitivity of B. viridis oocytes to serotonin, its agonists and antagonists is subject to seasonal changes. A maximum sensitivity of intact oocytes is observed in February-March, and that of denuded ones in May-June. We suggest that endogenous serotonin is involved in maintenance of the block of meiosis and in the oocyte maturation control in amphibians.

Animals↗
PubMed1984

Serotonin antagonists.

The realisation that serotonin plays a role not only in the carcinoid syndrome but also in migraine, nociception, dumping syndrome, vascular disease and hypertension, has led to an enormous amount of activity in search of serotonin antagonists. Numerous such pharmacological agents have been identified but only few have found their way into clinical use. All of them are competitive serotonin inhibitors, in that they vie for the same receptor as the amine itself and are thus able to block its action as well as imitate its effects. By far the widest use of such inhibitors is in the prevention of migraine, where they have effectively eliminated the dread of an attack from the life of the majority of patients. Whilst useful in the control of diarrhea in patients with carcinoid and dumping syndromes, their role in these diseases is limited. However, the possible role of serotonin in hypertension and nociception opens new avenues in the use of existing serotonin antagonists and calls for the discovery of a new generation of such pharmacological agents for the control of these conditions.

Cyproheptadine↗
PubMed1982

Actions of serotonin antagonists on dog coronary artery.

Serotonin released from platelets may initiate coronary vasospasm in patients with variant angina. If this hypothesis is correct, serotonin antagonists without constrictor activity may be useful in this form of angina. We have investigated drugs classified as serotonin antagonists on dog circumflex coronary artery ring segments in vitro. Ergotamine, dihydroergotamine, bromocriptine, lisuride, ergometrine, ketanserin, trazodone, cyproheptadine and pizotifen caused non-competitive antagonism of serotonin concentration-response curves. In addition, ketanserin, trazodone, bromocriptine and pizotifen inhibited noradrenaline responses in concentrations similar to those required for serotonin antagonism. All drugs with the exception of ketanserin, cyproheptadine and pizotifen showed some degree of intrinsic constrictor activity. Methysergide antagonized responses to serotonin competitively but also constricted the coronary artery. The lack of a silent competitive serotonin antagonist precludes a definite characterization of coronary serotonin receptors at this time. However, the profile of activity observed for the antagonist drugs in the coronary artery differs from that seen in other vascular tissues. Of the drugs tested, ketanserin may be the most useful in variant angina since it is a potent 5HT antagonist, lacks agonist activity and has alpha-adrenoceptor blocking activity.

Adrenergic alpha-Antagonists↗
PubMed1983

Hypotensive activity of serotonin antagonists; correlation with alpha 1-adrenoceptor and serotonin receptor blockade.

For a series of 12 serotonin antagonists, largely varying in potency, the decrease in diastolic pressure was determined after intravenous injection into pentobarbitone-anaesthetized normotensive rats. The hypotensive activity of these antagonists was correlated with their affinity for alpha 1-adrenoceptors, established by [3H]prazosin radioligand displacement, and the 5-HT2 serotonergic receptor, determined by inhibition of specific [3H]mianserin binding. The radioligand binding assays were performed since they correspond to the in vivo antagonistic potencies of the antagonists at alpha 1--and 5-HT2-receptors, respectively. A close correlation (r = 0.963) was found between the affinity for alpha 1-adrenoceptors and hypotensive activity. On the other hand, a negative correlation of lower statistical quality (r = -0.808) existed between the affinity for 5-HT2-receptors and the depressor potency. In this series of 12 compounds, the new antihypertensive drug ketanserin is included for which it has been speculated that it lowers blood pressure by virtue of its serotonin antagonistic activity. The results of the present study, however, point towards alpha 1-adrenolytic potency as an important mechanism in the hypotensive action of the drug.

Animals↗
PubMed1984

Differential actions of serotonin antagonists on two behavioral models of serotonin receptor activation in the rat.

Ligand binding studies have identified certain serotonin (5-HT) antagonists with selective affinity for 5-HT2 receptors and other serotonin antagonists with affinity for both 5-HT1 and 5-HT2 receptors. This study compared the actions of ketanserin and pipamperone, selective 5-HT2 receptor antagonists, with metergoline and methysergide, nonselective 5-HT antagonists, on two behavioral responses in rats that are produced by the activation of 5-HT receptors: 1) the head shake response and 2) the 5-HT syndrome. Both the selective and the nonselective 5-HT antagonists blocked the head shake response produced by 5-hydroxy-L-tryptophan. The order of relative potency was: metergoline greater than ketanserin greater than pipamperone greater than methysergide. All four antagonists also blocked the head shake response produced by the 5-HT agonist quipazine. In contrast, the symptoms of the 5-HT syndrome produced by 5-methoxy-N,N-dimethyltryptamine were blocked by pretreatment with the nonselective 5-HT receptor antagonists but not by the 5-HT2 receptor antagonists. The differential actions of 5-HT antagonists on these behavioral responses suggest that different 5-HT receptors are involved in the head shake response and the 5-HT syndrome. That the order of relative potency for these drugs to block the head shake response was the same as their reported affinity for the 5-HT2 receptor suggests that the 5-HT2 receptor is involved in the head shake response. In contrast, the ability of 5-HT antagonists with affinity for the 5-HT1 receptor to block the 5-HT syndrome and the inability of 5-HT2 receptor antagonists to block the syndrome suggests that this behavioral response probably involves the activation of 5-HT1 receptors.

Animals↗
PubMedDate not supplied

[Reception and extrareceptor binding of cytostatic serotonin antagonists by early embryos of the sea urchin Arbacia lixula].

Unfertilized eggs and early embryos of the sea urchin Arbacia lixula incubated for 60 min in a medium containing the antagonists of prenervous serotonin, i.e. inmecarb (21 microM) or imipramine (40 microM), bind up to 5 microM of these drugs per 1 ml of cells. At high cell concentrations (more than 10,000 eggs or embryos per 1 ml), this binding is not followed by inhibition of cleavage divisions or by increase in the sensitivity to cytostatic effects of these drugs, which is taken as an indication that this binding is a nonreceptive one. The decrease in concentration of eggs or embryos does not affect total binding of the drugs, although their antiserotonin effects become evident indicating the existence of the receptor sites of binding. In experiments with 3H-imipramine, two binding pools were found (Bmax being correspondingly equal to about 20 and 0.75 microM/ml of embryos; the values of Kd amount to 200 and 15 microM). One of them is a nonreceptive pool, whereas the other presumably coincides with receptor binding sites of prenervous serotonin antagonists.

Animals↗
PubMed2004

Effect of treatment at weaning with the serotonin antagonist mianserin on the brain serotonin and cerebrospinal fluid nocistatin level of adult female rats: a case of late imprinting.

Four weeks old (weanling) female rats were treated with the tricyclic antidepressant and histamine/serotonin receptor blocker mianserin for studying its faulty hormonal imprinting effect. Measurements were done four months later. Brain serotonin levels significantly decreased in four regions (hippocampus, hypothalamus, striatum and brainstem), without any change in the cortex. Sexual activity of the treated and control rats was similar. Cerebrospinal fluid nocistatin level was one magnitude higher in the treated rats, than in the controls. The density of uterine estrogen receptors was significantly reduced, while binding capacity of glucocorticoid receptors of liver and thymus remained at control level. The results call attention to the possibility of 1. a broad spectrum imprinting at the time of weaning by a receptor level acting non-hormone molecule 2. imprinting of the brain in a non-neonatal period of life and 3. a very durable (lifelong?) effect of the late imprinting with an antidepressant.

Animals↗
PubMed1985

The influence of ritanserin, a serotonin antagonist, in anxiety disorders: a double-blind placebo-controlled study versus lorazepam.

A double-blind study was performed in 83 patients with generalized anxiety disorder comparing daily doses of 5 and 10 mg ritanserin (a selective antagonist of serotonine S2 receptors) versus placebo and 4 mg lorazepam as reference drug. Patients treated with 10 mg ritanserin or 4 mg lorazepam improved significantly better (p less than 0.05) after two weeks than those treated with placebo. On the other hand a daily dose of 5 mg ritanserin appeared to be not superior to placebo. Patients treated with 4 mg lorazepam complained significantly more about sedation and dizziness than patients treated with 10 mg ritanserin (p less than 0.05).

Adult↗
PubMed1991

A single-blind comparison of intravenous ondansetron, a selective serotonin antagonist, with intravenous metoclopramide in the prevention of nausea and vomiting associated with high-dose cisplatin chemotherapy.

Ondansetron (GR 38032F), a selective antagonist of serotonin subtype 3 receptors, is effective in the prevention of emesis associated with cisplatin as well as other chemotherapeutic agents. In this randomized, single-blind, multicenter, parallel group study, we compared the efficacy and safety of intravenous (IV) ondansetron with IV metoclopramide in the prevention of nausea and vomiting associated with high-dose (greater than or equal to 100 mg/m2) cisplatin chemotherapy. Three hundred seven patients receiving their first dose of cisplatin, either alone or in combination with other antineoplastic agents, were randomized to receive ondansetron 0.15 mg/kg IV every 4 hours for three doses or metoclopramide 2 mg/kg IV every 2 hours for three doses, then every 3 hours for three additional doses. The study prohibited the concurrent administration of other antiemetics or dexamethasone. Patients receiving ondansetron had a higher rate of complete protection from emesis (40% v 30%, P = .07), a higher complete plus major response rate (65% v 51%, P = .016), a lower rate of failure (21% v 36%, P = .007), and a lower median number of emetic episodes (one v two, P = .005) than did those receiving metoclopramide. The median time to the first emetic episode was longer on ondansetron (20.5 v 4.3 hours, P less than .001). Adverse events occurred in 48% of patients receiving ondansetron and 69% of those receiving metoclopramide (P less than .001). Akathisia and acute dystonic reactions occurred only on metoclopramide; headache (controlled with acetaminophen) was significantly more frequent with ondansetron. Ondansetron is more effective, produces fewer adverse events, and is easier to administer than metoclopramide for the prevention of emesis associated with high-dose cisplatin chemotherapy.

Adult↗
PubMed1975

Blockade of the stimulus properties of mescaline by a serotonin antagonist.

It is known that the effects of mescaline (3, 4, 5-trimethoxyphenylethylamine), a hallucinogen, can function as a discriminative stimulus. The present investigation examined the ability of cinanserin, a serotinin antagonist, to block the stimulus properties of mescaline in the rat. After a reliable discrimination was established between the effects following the injection of mescaline (10 mg/kg) and those following administration of saline, subjects were pretreated with cinanserin HC1 (3 mg/kg) and then treated with mescaline. Such pretreatment was found to block discrimination, i.e., the response rate following the administration of mescaline plus cinanserin was appropriate for the saline condition. The present data suggest that antagonists of serotonin may be useful in furthering our understanding of phenethylamine hallucinogens.

Animals↗