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

Drugs that enhance gastrointestinal motility include the benzamide drugs metoclopramide, cisapride and renzapride (BRL-24924). Because these agents also are serotonin-3 (5-HT3) receptor antagonists, which can promote gastric emptying in some species, the motor-stimulating properties of benzamide agents may be due to this mechanism. Metoclopramide (0.3-3.0 mg/kg i.v.), cisapride (0.03-1.0 mg/kg i.v.) and BRL-24924 (0.01-0.1 mg/kg i.v.) were evaluated for their relative motility-stimulating and 5-HT3 receptor antagonist activities in conscious dogs and were compared with selective 5-HT3 antagonist antiemetic compounds ICS-205-930, (3 alpha-tropanyl)1-H-indole-3-carboxylic acid ester and granisetron (BRL-43694). Gastric antral contractions and intestinal myoelectric motility were determined in response to drugs, as were their effects on solid and liquid emptying in a gamma scintigraphic model of gastroparesis. 5-HT3 receptor antagonist potency was examined by deriving ED50 values for inhibition of cisplatin emesis. All drugs were 5-HT3 antagonists as they blocked cisplatin emesis with relative potencies of BRL-43694 = ICS-205-930 greater than BRL-24924 greater than cisapride = metoclopramide. The order of potency for stimulating fasted dog antral contractile activity, however, was BRL-24924 = cisapride greater than metoclopramide greater than ICS-205-930 = BRL-43694. Maximally effective doses of BRL-24924 (0.1 mg/kg i.v.) and cisapride (0.67 mg/kg i.v.) in the antrum also stimulated intestinal myoelectrical activity, whereas ICS-205-930 (0.5 and 2.0 mg/kg i.v.) was not active.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Relationship of serotonin-3 receptor antagonist activity to gastric emptying and motor-stimulating actions of prokinetic drugs in dogs. 207 88

The gastrokinetic activity of 2[1-(4-piperonyl)piperazinyl]benzothiazole (VB20B7), a new compound with 5-HT4 receptor agonist and weak 5-HT3 receptor antagonist properties has been studied in rats and dogs. The effects of VB20B7 were investigated in physiological conditions and in a model of gastroparesis induced by the alpha 2-adrenergic agonist UK-14304 and compared with cisapride. In rats, both VB20B7 and cisapride enhanced gastric emptying of indigestible solids (steel spheroids) and liquids (phenol red) at doses of 5-10 mg kg-1 by mouth. Gastric emptying of solid radiopaque markers in fasted beagle dogs was enhanced significantly by VB20B7 (0.25-1 mg kg-1 p.o.) whereas the effect of cisapride (0.5-2 mg kg-1 p.o.) did not reach statistical significance. Similar results were found when the radiopaque markers were given to the dogs following a standard solid meal. The delayed gastric emptying of indigestible solids and radiopaque markers by UK-14304 was reversed by oral administration of VB20B7 in both rats and dogs. Cisapride, however, was only effective in rats. In addition, gastric emptying of a digestible solid/liquid meal was assessed by quantitating the rate of appearance of the radioactive markers in the duodenum of dogs. VB20B7 (0.2-1 mg kg-1, i.v.) enhanced gastric emptying of both solid and liquid phases while cisapride only enhanced emptying of the solid phase. The present study indicates that acute oral and intravenous administration of VB20B7 accelerates gastric emptying of both solids and liquids in different animal models.
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PMID:VB20B7, a novel 5-HT-ergic agent with gastrokinetic activity. II. Evaluation of the gastroprokinetic activity in rats and dogs. 912 Jul 73

The influence of diabetic hyperglycemia on solid gastric emptying in rats was examined. Diabetes was produced by streptozotocin (STZ, 40 mg/kg i.v.), and diabetic hyperglycemia was observed from 1 day after the STZ injection. The gastric emptying of glass beads in the diabetic rats was significantly delayed compared with that in age-matched control rats at 1, 3 and 7 days after diabetes induction. A slight decrease in gastric emptying was observed in the diabetic rats from 2 to 52 weeks after the diabetes induction. We also investigated the influence of gastroprokinetic agents on STZ-induced diabetic gastroparesis and subdiaphragmatic vagotomy-induced gastroparesis in rats. The selective 5-HT3 receptor antagonists ramosetron (YM060), YM114 (KAE-393), granisetron and ondansetron, and the substituted benzamides (5-HT4 receptor agonist/5-HT3 receptor antagonists) cisapride mosapride and SC-53116 dose-dependently enhanced gastric emptying in normal rats. These compounds also reversed the impairment of diabetic gastroparesis rats at 7 days after the STZ injection, but higher doses were required. The solid gastric emptying in subdiaphragmatic vagotomized rats was also delayed. Ramosetron and the substituted benzamides cisapride and zacopride partially reversed the gastroparesis in the vagotomized rats. These results suggest that acute hyperglycemia is important mechanism for the delay of solid gastric emptying in diabetic rats. It is also suggested that selective 5-HT3 receptor antagonists and substituted benzamides enhance gastric emptying not only in normal rats but also in diabetic and vagotomized rats.
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PMID:Effects of gastroprokinetic agents on gastroparesis in streptozotocin-induced diabetic rats. 922 2

Nausea and vomiting are debilitating symptoms complicating many clinical conditions. Conventional antiemetic agents act as muscarinic, histamine, and dopamine receptor antagonists in the central nervous system. In a retrospective analysis, tricyclic antidepressant drugs demonstrated efficacy in long-term treatment of functional nausea. Some cases of vomiting result from impaired gastrointestinal motor activity. Agents which act on gastric serotonin (5-HT4), dopamine, and motilin receptors accelerate gastric emptying and relieve symptoms in gastroparesis. Recent investigations suggest that some patients with refractory gastroparesis may benefit from gastric electrical pacing. The treatment of acute chemotherapy-induced emesis was revolutionized by 5-HT3 receptor antagonists; however, these agents are less efficacious in delayed vomiting. Neurokinin (NK-1) receptor antagonists show promise in treating delayed chemotherapy-evoked emesis. Furthermore, animal studies indicate a broad spectrum of action for NK-1 antagonists in treating diverse causes of nausea and vomiting. The cyclic vomiting syndrome is characterized by discrete episodes of relentless vomiting separated by asymptomatic intervals and is associated with migraine headaches. Antimigraine therapies including the 5-HT1D receptor agonists sumatriptan reduce the severity of cyclic vomiting attacks. Investigations into these and other novel treatments may provide important advances in the care of difficult cases of nausea and vomiting resulting from disparate illnesses.
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PMID:Novel approaches to the treatment of nausea and vomiting. 1069 61

This study aimed to dissect the mechanisms involved in malaise induced by the anti-cancer drug cisplatin by attempting to uncouple its effects on locomotor activity, arguably at least partly indicative of fatigue, from those effects indicative of emesis (pica, gastric stasis, reduced food intake) using pharmacological agents in the rat. Over 2 days cisplatin (6 mg/kg i.p.) reduced food intake, stimulated kaolin consumption, increased the wet weight of gastric contents and reduced locomotor activity. In animals treated with cisplatin: the 5-HT3 receptor antagonist ondansetron (1 mg/kg s.c. bd.) had no effect on either activity or weight of gastric contents but did increase food intake on day 1 (P<0.05) and the total over both days (27.6+/-1.8 vs. 19.9+/-2.3g, P<0.05), reducing kaolin consumption on day 2 (P<0.01) but not the total over both days; the NK1 receptor antagonist GR205171 (1 mg/kg s.c. bd.) was without effect on activity, but reduced the wet weight of gastric contents (P<0.05), increased food intake on day 2 (P<0.01) and total consumption over both days (28.1+/-1.7 g vs. 19.9+/-2.3 g; P<0.05) and reduced kaolin consumption on day 2 (P<0.05) but not over both days; dexamethasone (2 mg/kg s.c. bd.) blocked the cisplatin-induced reduction in activity on days 1 and 2 (P<0.01), reduced the wet weight of gastric contents by 43% (P<0.01), reduced kaolin consumption on both days (P<0.01) and arguably decreased the reduction in food intake caused by cisplatin. This study has revealed novel insights into the different spectra of activities of 5-HT3 and NK1 receptor antagonists and dexamethasone, which have implications for therapeutic strategies to alleviate the emetic, anorectic, dyspeptic and activity-reducing effects of anti-cancer chemotherapy.
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PMID:Differential effects of dexamethasone, ondansetron and a tachykinin NK1 receptor antagonist (GR205171) on cisplatin-induced changes in behaviour, food intake, pica and gastric function in rats. 1714 Dec 13

Serotonin (5-HT) is involved in the regulation of motoric and sensory functions of the upper gastrointestinal tract. The aim of the current study was to determine whether serotonergic signalling is altered in patients with idiopathic gastroparesis. Mucosal biopsy specimens were collected from the duodenum, antrum and fundus of 11 patients with idiopathic gastroparesis and 11 healthy controls. Neuroendocrine cells, specifically 5-HT producing cells, were counted after immunohistochemistry, and non-neuronal mRNA expression levels of tryptophan hydroxylase (TPH)-1, 5-HT transport protein (SERT), 5-HT3 and 5-HT4 receptor were quantified by real time RT-PCR. The number of 5-HT producing cells was comparable between patients and controls. No difference in expression of TPH-1 (rate limiting enzyme in 5-HT biosynthetic pathway) and SERT (responsible for 5-HT uptake) was found between patients and controls (P > 0.05). In the duodenum, the expression of the 5-HT3 receptor subunits and the 5-HT4 receptor was comparable between both groups. However, the 5-HT4(c) splice variant was expressed more abundantly in healthy controls compared to patients (P = 0.015). This study suggests that the delayed gastric emptying and upper abdominal symptoms in idiopathic gastroparesis do not result from altered mucosal 5-HT biosynthetic and uptake capacity.
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PMID:Serotonergic signalling in the stomach and duodenum of patients with gastroparesis. 1820 80

Renzapride is a novel drug currently under clinical evaluation for the treatment of irritable bowel syndrome (IBS). Renzapride is a mixed 5-hydroxytryptamine type 4 (5-HT4) agonist and 5-HT3 receptor antagonist that has a stimulatory effect on gastrointestinal motility and transit, as established by in vivo and in vitro studies. Its therapeutic efficacy, tolerability and safety have been evaluated in diabetic gastroparesis in a single study, as well as in IBS in a few other studies. Phase II studies indicated potential beneficial effects on symptoms and bowel habits in patients with constipation-predominant IBS and mixed-type IBS. The outcome of Phase III studies is currently under evaluation.
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PMID:Renzapride: a new drug for the treatment of constipation in the irritable bowel syndrome. 1892 3

Nausea is one of a cluster of symptoms described subjectively by patients with delayed gastric emptying. The mechanisms and treatments are unclear (anti-emetic drugs are not fully effective against nausea). Can nausea be relieved by stimulating gastric emptying? Physostigmine (together with atropine) has been shown experimentally to stimulate gastric motility, relieve nausea and restore normal gastric motility. Is this mimicked by gastric prokinetic drugs? The answer is complicated by mixed pharmacology. Metoclopramide increases gastric motility by activating myenteric 5-HT4 receptors but also directly inhibits vomiting via D2 and 5-HT3 receptor antagonism; relationships between increased gastric motility and relief from nausea are therefore unclear. Similarly, the D2 receptor antagonist domperidone has direct anti-emetic activity. Nevertheless, more selective 5-HT4 and motilin receptor agonists (erythromycin, directly stimulating gastric motility) inhibit vomiting in animals; low doses of erythromycin can also relieve symptoms in patients with gastroparesis. Ghrelin stimulates gastric motility and appetite mostly via vagus-dependent pathways, and inhibits vomiting in animals. To date, ghrelin receptor activation has failed to consistently improve gastric emptying or symptoms in patients with gastroparesis. We conclude that nausea can be relieved by gastric prokinetic drugs, but more clinical studies are needed using drugs with selective activity. Other mechanisms (e.g. ghrelin, vagal and central pathways, influencing a mechanistic continuum between appetite and nausea) also require exploration. These and other issues will be further explored in a forthcoming special issue of the European Journal of Pharmacology, which focusses on mechanisms of nausea and vomiting.
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PMID:The relationship between gastric motility and nausea: gastric prokinetic agents as treatments. 2383 91

The activation of Corticotrophin Releasing-Factor (CRF) receptors in the brain is well established to coordinate the endocrine, behavioral, autonomic and visceral responses to stress. In addition, CRF receptors are also expressed within the gut where they exert biological actions and play a role in modulating stress-related gastrointestinal function. In particular, peripheral injection of CRF and related peptides, urocortin 1, 2 or 3 inhibit Gastric Emptying (GE) and alters fasted and fed pattern of gastroduodenal motility in several experimental species. Urocortin 1 interacts synergistically with cholecystokin-8 to inhibit gastric emptying in lean mice which is no longer observed in diet-induced obese rats. In in vitro circular or longitudinal muscle preparation of rat antrum, CRF and urocortin 1 and 2 suppressed spontaneous contractile activity. CRF and urocortins interact with the CRF receptor 2 (CRF-R2) to inhibit gastric motor function monitored both in vivo and in vitro. The CRF-R2 mediated inhibition of antral and corpus contractility involves a direct action on gastric myenteric neurons where CRF-R2 is expressed and may also involve the activation of serotonin acting on 5-HT3 receptor. The involvement of peripheral CRF receptors in gastric motor alterations occurring under stress conditions are stressors specific with CRF-R2 mediating the early phase of gastric ileus induced by abdominal surgery and the delayed emptying elicited by acute restraint stress. However gastric stasis elicited by endotoxin is not mediated by CRF-R2 and CRF receptors are not involved in the basal regulation of fed or fasted pattern of gastric motility.
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PMID:Peripheral Corticotropin Releasing Factor Signaling Inhibits Gastric Emptying: Mechanisms of Action and Role in Stress-related Gastric Alterations of Motor Function. 2824 60