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)

The vasodilator mechanism of the putative serotonin1A (5-HT) receptor agonists, urapidil, 5-methyl-urapidil, ipsapirone, flesinoxan and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) was investigated in constant-pressure perfused rat kidneys. The compounds (10(-12)-10(-7) mol bolus injection) neither enhanced basal flow nor evoked vasodilatation in kidneys preconstricted by 27 mM KCl, 1.5 mM BaCl2 or 10(-6) M prostaglandin (PG)F2 alpha, but evoked a dose-dependent, reversible and spiroxatrine-resistant increase in vasodilatation of organs preconstricted by 6 x 10(-7) M noradrenaline. 5-Carboxamidotryptamine and sumatriptan did not reverse the vasoconstriction induced by all stimuli or that induced by noradrenaline in the presence of 5-HT2 plus 5-HT3 receptor blockade. No correlation for the vasorelaxant drugs was found between their -log ED50 in rat kidney and pKi values at 5-HT1A binding sites in pig cortex as determined in radioligand experiments. The relaxation in rat kidney induced by 5-HT1A receptor agonists and alpha 1A-adrenoceptor-selective antagonists (WB 4101 and (+)-niguldipine) was significantly correlated with pKi values at alpha 1A binding sites in rat cortex and the pA2 values derived from contraction studies for competitive antagonism at alpha 1-adrenoceptors in prostatic portions of the rat vas deferens, but differed from pKi values for alpha 1B binding sites in rat cortex. Thus, the vasodilator effect of the 5-HT1A receptor agonists urapidil, 5-methyl-urapidil, ipsapirone, flesinoxan and 8-OH-DPAT in the noradrenaline-perfused rat kidney appears to be mediated by their concomitant alpha 1A-adrenoceptor blockade. No evidence for a vasodilator effect mediated through 5-HT1A receptors was found under our experimental conditions.
Eur J Pharmacol 1991 Sep 04
PMID:Vasodilatation elicited by 5-HT1A receptor agonists in constant-pressure-perfused rat kidney is mediated by blockade of alpha 1A-adrenoceptors. 168 54

1. The effect of serotonin on inhibitory synaptic transmission was examined in forty-one CA1 pyramidal neurones using intracellular voltage recordings in vitro. 2. Serotonin (20-50 microM) increased the synaptic noise of most (85%) neurones loaded with chloride (n = 33). The duration of this effect was enhanced with increasing concentrations of serotonin and was fully reversible within 5 min. When serotonin was applied at short intervals (less than 10 min), fading of the response was observed. 3. The effect of serotonin on synaptic noise persisted in the presence of the glutamate NMDA and non-NMDA antagonists, APV (100 microM) and CNQX (10 microM), but it was blocked (n = 5) by a GABAA antagonist, bicuculline (10 microM). 4. The increase in inhibitory synaptic events resulted from an enhanced frequency of unitary IPSPs from 4.6 +/- 3.8 Hz in control to 17.2 +/- 12.5 Hz (n = 5) in serotonin, especially of large events. Serotonin caused no change in the amplitude and frequency of miniature synaptic events recorded in the presence of TTX (n = 5). The mean amplitude of unitary inhibitory postsynaptic potentials (IPSPs) increased from 1.37 +/- 0.35 mV in control to 3.67 +/- 1.38 mV in serotonin. The coefficient of variation of unitary IPSPs increased from 0.40 +/- 0.11 in control to 0.74 +/- 0.23 in serotonin when quantal size appeared unchanged. 5. The 5-HT3 agonist 2-methyl-serotonin (52 microM, n = 4) partially mimicked the effect of serotonin, increasing the inhibitory noise without affecting the pyramidal neurone conductance. The serotonin-induced facilitation of unitary IPSPs was blocked by the 5-HT3 antagonists ICS 205-930 (1-90 nM, n = 3) and metoclopramide (30 microM, n = 1). 6. These results suggest that serotonin directly excites GABAergic interneurones acting on a 5-HT3 receptor and consequently increasing the frequency of inhibitory synaptic events recorded in CA1 pyramidal cells.
J Physiol 1991 Sep
PMID:Serotonin facilitates GABAergic transmission in the CA1 region of rat hippocampus in vitro. 168 46

Using immunohistochemical techniques, a large number of serotonergic paracrine cells were identified in the urethral mucosa of the female rat. The functional significance of these cells was investigated. A model for the study of sexual climax in the anesthetized, acutely spinalized female rat was used. In this model, distension of the urethra with saline elicits a stereotyped coordinated genital response which closely resembles the neuromuscular concomitants of sexual climax. Addition of serotonin to the urethral perfusate (10(-4)-10(-7) M) caused a dose-dependent decrease in the mechanical threshold necessary to elicit the climax-like response. This effect was blocked by a specific 5-HT3 receptor antagonist. The physiological implications of these findings are discussed.
Pharmacol Biochem Behav 1991 Sep
PMID:Modulation by peripheral serotonin of the threshold for sexual reflexes in female rats. 178 Mar 36

Ondansetron is a 5-hydroxytryptamine3 receptor antagonist for the treatment of chemotherapy- and radiotherapy-induced nausea and emesis. A sensitive, accurate, and precise HPLC method for the determination of ondansetron in plasma is described. Samples are prepared by solid-phase extraction and, after chromatography of the extracts on a silica analytical column, ondansetron is detected by UV absorbance at 305 nm. The method is sensitive down to 1 ng/mL, at which concentration the coefficient of variation was 6.2% in a single assay run. Repeated analyses of quality control samples, nominally at 2 ng/mL, were carried out over a number of assay runs with a coefficient of variation of 5.5%. The method is specific for ondansetron with respect to endogenous plasma components, identified phase I metabolites, and some co-administered chemotherapeutic drugs. In sustained use over several months, and in support of the clinical development of ondansetron, the method has been shown to be robust. An application of the assay in the investigation of the pharmacokinetics of ondansetron in the young and elderly is described.
J Pharm Sci 1991 Sep
PMID:Determination of ondansetron in plasma and its pharmacokinetics in the young and elderly. 183 13

The effects of cisapride on intestinal contractility and on release of acetylcholine (ACh) were examined using the longitudinal muscle with the myenteric plexus preparation from the guinea pig ileum, as related to the 5-hydoxytryptamine (5-HT) receptor. 5-HT exerted a dual effect, transient increase in ACh release (EC50 = 2 X 10(-6)M) via the 5-HT3 receptor, followed by inhibition (EC50 = 5 X 10(-9)M) via the 5-HT1 receptor. Cisapride at low concentrations (10(-9)M to 10(-8)M) enhanced electrical stimulation -evoked contraction and ACh release. The effect of cisapride was mimicked by methysergide and was not altered by ICS 205-930. Cisapride antagonized the 5-HT (5 X 10(-9) M)-induced inhibitory effect and the IC50 of cisapride was 1.5 X 10(-9) M. These findings indicate that enhancement by low concentrations of cisapride may be due to a block of the inhibitory 5-HT1 receptor. Cisapride at medium concentrations (10(-8) M to 3 X 10(-7) M) induced enhancement of electrical stimulation-evoked twitch contractions and ACh release evoked by electrical stimulation which were antagonized by 10(-6) M ICS 205-930, while this compound antagonized the 5-HT (2 X 10(-6) M)-and 2-methyl-5-HT-induced excitatory effects, and the IC50 of cisapride was 5.2 X 10(-8) M. Thus, cisapride acts on the putative 5-HT4 receptor as an agonist and the 5-HT3 receptor as an antagonist. Cisapride at high concentrations (10(-6) M to 10(-5) M) evoked contraction and the release of ACh, and these effects were antagonized by ICS 205-930 (10(-6) M).(ABSTRACT TRUNCATED AT 250 WORDS)
J Pharmacol Exp Ther 1991 Sep
PMID:Cisapride stimulates motility of the intestine via the 5-hydroxytryptamine receptors. 189 Jun 14

Chemical modification of the 5-HT3 receptors in membranes from NG108-15 hybridoma cells was achieved using protein modifying reagents specific for various amino acid residues: N-bromosuccinimide for tryptophan, dithiothreitol for cystine, sodium tetrathionate for cysteine, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline for aspartic and glutamic acids, diethylpyrocarbonate for histidine, tetranitromethane for tyrosine and 2,3-butanedione for arginine. Among all the reagents tested, N-bromosuccinimide produced the largest alteration in the specific binding of [3H]zacopride onto 5-HT3 receptors. A significant reduction in Bmax (approximately 50%) with no change in Kd were noted on [3H]zacopride specific binding to membranes which were incubated with 40 microM N-bromosuccinimide for 60 min at 25 degrees. The occupancy of 5-HT3 receptor binding sites by various 5-HT3 agonists and antagonists (phenylbiguanide, ondansetron, granisetron, MDL 72222) prevented, at least partially, any subsequent reduction in [3H]zacopride specific binding by N-bromosuccinimide treatment. However, neither m-chloro-phenylbiguanide, among the agonists, nor zacopride, among the antagonists, were able to prevent the effect of N-bromosuccinimide, suggesting that variations might exist in the molecular mechanisms implicated in the binding of 5-HT3 ligands to the recognition site on 5-HT3 receptors. Nevertheless, these data support the suggestion that tryptophan residue(s) are probably involved in the binding of agonists and antagonists onto 5-HT3 receptors in NG108-15 cell membranes.
Biochem Pharmacol 1991 Sep 12
PMID:Involvement of tryptophan residue(s) in the specific binding of agonists/antagonists to 5-HT3 receptors in NG108-15 clonal cells. 193 Feb 69

The 5-HT3 receptor antagonists, ICS205-930, granisetron and zacopride, at low doses, inhibited the hyperactivity caused by a 13 day mesolimbic dopamine infusion in the rat. The antagonism decreased with the use of higher doses of the 5-HT3 receptor antagonists. The ability of low doses of the 5-HT3 receptor antagonists to inhibit dopamine-induced behavioural changes is similar to the inhibitory profile of known antipsychotic agents. It is suggested that 5-HT3 receptor antagonists may represent a new class of atypical antipsychotic agents.
Neuroreport 1990 Sep
PMID:5-HT3 receptor antagonists attenuate dopamine-induced hyperactivity in the rat. 196 1

Ondansetron, a 5HT3 antagonist, was given to 20 children aged 4 to 18 years who were undergoing treatment with the Australian and New Zealand Childhood Cancer Study Group Acute Lymphocytic Leukaemia (ALL) Study V Protocol. The study was open, dose ranging, and noncomparative, and designed to evaluate safety and efficacy of ondansetron in preventing nausea and vomiting caused by cyclophosphamide intravenous (IV) 1,000 mg/m2 day 1, and cytarabine IV subcutaneously (SC) 75 mg/m2 on days 2 to 5. Ten patients were given ondansetron 5 mg/m2 IV (group A) and subsequently another 10 patients were given ondansetron 3 mg/m2 IV (group B). Oral ondansetron was given for 14 doses, at the same dosage for both groups, commencing simultaneously with the IV infusion and continuing at 8 hourly intervals, ie, until day 5. The oral dose was based on surface area with the following schedule: 0.3 to 0.6 m2, 2 mg; 0.6 to 1 m2, 3 mg; and greater than 1 m2, 4 mg. Vomiting on the first day of chemotherapy was reported in group A by one patient and by one patient in group B. Vomiting during days 2 to 5 was reported by two group-A patients and by three group-B patients. Nausea was recorded on day 1 by one patient in group A, and two in group B, and on days 2 to 5 by three patients in group A, and by seven in group B. All patients were alert during treatment with ondansetron and there was no dystonia. There were no changes in renal function or hematology values that could be ascribed to the study drug. Transient elevations in bilirubin and liver enzymes were observed. We conclude that our results indicate that ondansetron is a safe and extremely effective single-agent antiemetic with minimal side effects, when administered both IV and orally.
J Clin Oncol 1990 Sep
PMID:Prevention of cyclophosphamide/cytarabine-induced emesis with ondansetron in children with leukemia. 214 19

Sixty five chemotherapy naive patients receiving cisplatin (50-120 mg/m2) containing chemotherapy participated in an evaluation of ondansetron, a 5-HT3 receptor antagonist, in the prophylaxis of acute and delayed nausea and emesis. Ondansetron was given as three 0.15 mg/kg doses intravenously (0.5 h before, 3.5 h and 7.5 h after cisplatin) for acute emesis followed by 8 mg orally 8-hourly for five days at 24 h post-cisplatin for delayed emesis. For acute emesis (first 24 h, n = 63), complete control was achieved in 34 patients (54%) and major control (1-2 episodes) in 16 patients (25%). Complete protection from acute nausea was achieved in 48 patients (76%). For delayed emesis (days 2-6, n = 55), 33 patients (60%) were completely protected or reported one to two episodes during the entire 5-day observation period; 63% reported only mild or no nausea. Ondansetron was well tolerated with no significant drug-related adverse events. These results are consistent with serotonin being a significant transmitter of cisplatin-induced emesis.
Clin Oncol (R Coll Radiol) 1990 Sep
PMID:Ondansetron (GR38032) in the prophylaxis of acute and delayed cisplatin-induced emesis. 214 9

The highly selective 5-HT3 receptor antagonist [3H]GR65630 has been used to characterize 5-HT3 receptors in intact N1E-115 neuroblastoma cells. Equilibrium binding analysis demonstrated high-affinity binding to a single class of receptors with a Kd of 0.69 (+/- 0.12) nM and Bmax of 31.4 (+/- 11.4) fmol/10(5) cells, equivalent to approximately 200,000 sites per cell. Specific binding was displaced by low concentrations of 5-HT3-selective ligands, and by the nicotinic antagonist d-tubocurarine.
Eur J Pharmacol 1990 Sep 18
PMID:Characterization of 5-HT3 receptors in intact N1E-115 neuroblastoma cells. 225 4


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