Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P46098 (5-HT3 receptor)
 2,290 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antidepressants have previously been associated with paranoid reactions in psychiatric patients. Five cases of paranoid exacerbation with the serotonin reuptake inhibitors fluoxetine and amitriptyline are reported here. Elements common to these cases included a history of paranoid symptomatology and the concomitant occurrence of depressive and psychotic symptoms. Complicated depressive disorders (including atypicality of course and symptomatology, chronicity, psychosis, bipolarity, and secondary onset in the course of a primary psychosis) may present particular vulnerability to paranoid exacerbations associated with serotonin reuptake inhibitors. Although the pharmacology and neurobiology of paranoia remain cryptic, several mechanisms, including 5HT3 receptor-mediated dopamine release, beta-noradrenergic receptor downregulation, or GABAB receptor upregulation acting in the vicinity of the ventral basal ganglia (possibly in lateral orbitofrontal or anterior cingulate circuits), might apply to this phenomenon. These cases call attention to possible paranoid exacerbations with serotonin reuptake blockers in select patients and raise neurobiological considerations regarding paranoia.
Clin Neuropharmacol 1991 Dec
PMID:Serotonin reuptake inhibitors, paranoia, and the ventral basal ganglia. 183 56

The selective 5-HT3 receptor antagonist, ICS 205-930 (Sandoz), has potent effects on gastrointestinal motor activity in vitro and in vivo. This double-blind, crossover study compared the effects of 20 mg of ICS 205-930 infused intravenously with those of a placebo on the motor activity of the oesophageal body and the lower oesophageal sphincter (LOS). Each of twelve healthy young men participated in two recording sessions one week apart. Oesophageal pressures were recorded using a catheter assembly with orifices 2, 5, 8, 11, and 14 cm above the oral border of the LOS and a Dent sleeve for measurement within the LOS. During and after the infusion of ICS 205-930, amplitude and duration of swallow-initiated contractions in the smooth muscle oesophagus increased slightly, the area under the curve as a measure of contraction strength being significantly greater than after placebo (P less than 0.05). LOS resting pressure increased slightly during ICS 205-930 infusion and was significantly higher than it was in the case of the placebo (P less than 0.001). Propagation velocity of contractions, incidence of tertiary contractions and relaxation of LOS upon swallowing remained unaffected. ICS 205-930 was well tolerated. It is concluded that ICS 205-930 has slight but distinct stimulatory effects on contraction strength in the smooth muscle oesophagus and LOS resting pressure.
Hepatogastroenterology 1990 Dec
PMID:Effects of the 5-HT3 receptor antagonist, ICS 205-930, on oesophageal motor activity and on lower oesophageal sphincter pressure: a double-blind cross-over study. 208 22

1. The cardiovascular effects of the 5-HT2 antagonist ICI 169,369 have been investigated in pentobarbitone anaesthetized rats and in pithed rats whose blood pressure was supported by a vasopressin infusion. 2. In anaesthetized rats, cumulative doses (0.1-3.0 mg kg-1) of ICI 169,369 caused dose-related large transient falls in heart rate and blood pressure followed by a slow dose-related decline in both parameters. 3. Pretreatment with atropine methonitrate (1 mg kg-1) alone or in combination with atenolol (1 mg kg-1) or bi-vagotomy blocked the transient changes in blood pressure and heart rate caused by ICI 169,369. The long-term fall in heart rate was also attenuated by either atropine or atenolol; however, the combination of atenolol and atropine was more effective. None of the above pretreatments affected the long-term fall in blood pressure caused by ICI 169,369. 4. The cardiovascular effects of ICI 169,369 were unaffected by pretreatment with MDL 72222 (1 mg kg-1) and failed to show cross-tachyphylaxis with phenylbiguanide. 5. In pithed rats whose blood pressure was maintained with vasopressin, ICI 169,369 failed to cause any of the above transient and long-term effects on blood pressure and heart rate. 6. The study indicates that ICI 169,369 is capable of stimulating cardiopulmonary afferents through a non 5-HT3 receptor mechanism and has a central hypotensive action.
J Auton Pharmacol 1990 Dec
PMID:Evidence suggesting that the 5-HT2 antagonist ICI 169,369 activates vagal afferents and in addition has a central hypotensive action in anaesthetized rats. 209 95

R(+)- and S(-)-zacopride were assessed as potential 5-HT3 receptor antagonists in behavioural and biochemical tests. The S(-)isomer was more potent than the R(+)isomer to antagonise the hyperactivity induced by the injection of amphetamine or the infusion of dopamine into the nucleus accumbens in the rat. In contrast, the R(+)isomer was more potent to reduce the aversive behaviour of mice to a brightly illuminated environment and in a marmoset human threat test, to facilitate social interaction in rats, to increase performance in a mouse habituation test and prevent a scopolamine-induced impairment, and to antagonise the inhibitory effect of 2-methyl-5-hydroxytryptamine to reduce [3H]acetylcholine release in slices of the rat entorhinal cortex. In binding assays, [3H]S(-)-zacopride and [3H]R(+)-zacopride labelled homogenous populations of high-affinity binding sites in the rat entorhinal cortex, R(+)-zacopride compete for a further 10 to 20% of the binding of [3H]R(+)/S(-)-zacopride or [3H]R(+)-zacopride in excess of that competed for by (S)(-)-zacopride. It is concluded that both isomers of zacopride have potent but different pharmacological activities, with the possibility of different recognition sites to mediate their effects.
Pharmacol Biochem Behav 1990 Dec
PMID:The differential activities of R (+)- and S(-)-zacopride as 5-HT3 receptor antagonists. 212 57

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.
J Med Chem 1990 Dec
PMID: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. 225 3

The results of an open study designed to evaluate the prevention of cisplatin-induced emesis by the specific 5-HT3 receptor antagonist ICS 205-930 are reported. Fifty-four cancer patients, treated with diverse chemotherapy regimens, all including cisplatin (greater than = 50 mg/m2), received ICS 205-930 for a total of 165 courses. ICS 205-930 (10 mg) was given i.v. immediately before the cisplatin infusion and a second 10-mg dose was given immediately after. In 109 courses (66%) the patients did not have any vomiting episodes. Nausea was absent in 44.8% of courses. More than 3 vomiting episodes occurred only in 17 (10.4%) courses, and severe nausea only in 11 (6.6%). ICS 205-930 was extremely well tolerated. Mild headache occurred during 7 courses (4.2%) in 4 patients, hypotension during 5 courses (3%) in 3 patients and lipothymia in 2 courses (1.2%) in 2 patients. These results suggest that ICS 205-930 is an effective and well tolerated antiemetic drug in patients receiving cisplatin chemotherapy.
Tumori 1990 Dec 31
PMID:Prevention of nausea and vomiting in cisplatin-treated patients by a selective 5-hydroxytryptamine (5-HT3) receptor antagonist, ICS 205-930. 228 99

Ionic currents induced by 5-hydroxytryptamine (5-HT) in cultured neuroblastoma N18 cells were studied using whole-cell voltage clamp. The response was blocked by 1-10 nM 5-HT3 receptor-specific antagonists MDL 7222 or ICS 205-930, but not by 1 microM 5-HT1/5-HT2 receptor antagonist spiperone or 5-HT2 receptor-specific antagonist ketanserin. These 5-HT3 receptors seem to be ligand-gated channels because the response (a) did not require internal ATP or GTP, (b) persisted with long internal dialysis of CsF (90 mM), A1F4- (100 microM), or GTP gamma S (100 microM), and (c) with ionophoretic delivery of 5-HT developed with a delay of less than 10 ms and rose to a peak in 34-130 ms. Fluctuation analysis yielded an apparent single-channel conductance of 593 fS. The relative permeabilities of the channel for a variety of ions were determined from reversal potentials. The channel was only weakly selective among small cations, with permeability ratios PX/PNa of 1.22, 1.10, 1.01, 1.00, and 0.99 for Cs+, K+, Li+, Na+, and Rb+, and 1.12, 0.79, and 0.73 for Ca2+, Ba2+, and Mg2+ (when studied in mixtures of 20 mM divalent ions and 120 mM N-methyl-D-glucamine). Apparent permeability ratios for the divalent ions decreased as the concentration of divalent ions was increased. Small monovalent organic cations were highly permeant. Large organic cations such as Tris and glucosamine were measurably permeant with permeability ratios of 0.20 and 0.08, and N-methyl-D-glucamine was almost impermeant. Small anions, NO3-, Cl-, and F-, were slightly permeant with permeability ratios of 0.08, 0.04, and 0.03. The results indicate that the open 5-HT3 receptor channel has an effective minimum circular pore size of 7.6 A and that ionic interactions in the channel may involve negative charges near the pore mouth.
J Gen Physiol 1990 Dec
PMID:Ion permeation through 5-hydroxytryptamine-gated channels in neuroblastoma N18 cells. 228 32

The radiation inactivation technique has been used to estimate the molecular size of the 5-HT3 receptor binding site labelled by [3H]zacopride, in comparison with that of the 5-HT1A receptor binding site labelled by [3H]8-OH-DPAT, in rat cortical membranes. The calculated molecular weight of the 5-HT3 site: 35.4 +/- 2.2 kDa (mean +/- S.E.M., n = 4) was significantly less than that of the 5-HT1A site: 62.9 +/- 1.8 kDa (mean +/- S.E.M., n = 4) and of other 5-HT1 and 5-HT2 receptors of the G-protein coupled family. These data further support that the 5-HT3 receptor is not coupled to G-proteins in the rat brain.
Eur J Pharmacol 1989 Dec 05
PMID:Determination of the molecular size of the 5-HT3 receptor binding site by radiation inactivation. 253 81

This study has employed receptor autoradiography to localise the distribution of binding sites for the 5-HT3 receptor ligand [3H]BRL 43694 in sections of the brain of the rat (using a concentration of 10 nM [3H]BRL 43694 with 100 microM GR38032F to define non-specific binding). The highest density of binding sites for [3H]BRL 43694 was observed in the nucleus tractus solitarius and amounted to 652 fmol/mg tissue. The binding of [3H]BRL 43694 was also examined in sections prepared 10 days after unilateral nodose ganglionectomy, in an attempt to determine the neuronal location of these binding sites. Denervation reduced the binding of [3H]BRL 43694 by around 50% in the ipsilateral side of the nucleus tractus solitarius, relative to the contralateral side. This would indicate that the 5-HT3 binding sites may have a presynaptic location on vagal afferent terminals.
Neuropharmacology 1989 Dec
PMID:The 5-HT3 receptor ligand, [3H]BRL 43694, binds to presynaptic sites in the nucleus tractus solitarius of the rat. 255 49

Using rat and mouse models of aversive behaviour, we have further investigated the properties of the 5-HT3 receptor antagonist ondansetron (GR38032F) that are relevant to its proposed use as an anxiolytic agent. Tolerance to the disinhibitory properties of diazepam was readily demonstrated in the social interaction test in the rat, but did not occur after subchronic treatment with ondansetron. In both the light/dark exploration test in mice and the social interaction test in rats, withdrawal from subchronic treatment with diazepam increased behavioural suppression, whereas this was not observed with ondansetron. The behavioural suppression and weight loss induced by either the withdrawal of diazepam or the administration of the benzodiazepine receptor antagonist, flumazenil, in animals treated subchronically with diazepam, was prevented or antagonised by diazepam or ondansetron. Buspirone was ineffective. It is concluded that, in rats and mice, tolerance to the disinhibitory effects of ondansetron does not occur, that withdrawal from subchronic treatment with ondansetron is not associated with any behavioural disturbances and that ondansetron is highly effective in preventing the behavioural suppression and weight loss following withdrawal from subchronic diazepam treatment. These data suggest that ondansetron may have major therapeutic advantages over currently available anxiolytic agents, particularly in patients who have previously received prolonged benzodiazepine therapy.
Pharmacol Biochem Behav 1989 Dec
PMID:The effects of ondansetron (GR38032F) in rats and mice treated subchronically with diazepam. 257 43


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