GR 125487 sulfamate

Possible involvement of 5-HT4 receptors, in addition to 5-HT3 receptors, in the emesis induced by high-dose cisplatin in Suncus murinus.[Pubmed:11243577]

Jpn J Pharmacol. 2001 Jan;85(1):70-4.

To clarify the mechanism for the severe emesis concomitant with intensive chemotherapy, we investigated the effects of 5-HT3- and 5-HT4-receptor antagonists on the emesis induced by the high-dose of cisplatin in Suncus murinus. The emesis induced by 50 mg/kg of cisplatin was reduced by the oral pretreatment with tropisetron, which is known as a 5-HT3- and 5-HT4-receptor dual antagonist in vitro, with the ID50 value of 0.52 mg/kg. On the contrary, granisetron, a selective 5-HT3-receptor antagonist, did not markedly inhibit the emesis at up to 30 mg/kg. Moreover, GR125487, a selective 5-HT4-receptor antagonist, did not inhibit the emesis. However, co-administration of GR125487 and granisetron significantly reduced the number of emetic episodes. The study of the co-administration of GR125487 with tropisetron showed that GR125487 did not further enhance the inhibitory effect of tropisetron alone, suggesting that the anti-emetic effect of tropisetron is mediated via the blockade of both 5-HT3 and 5-HT4 receptors. These results suggest that both the 5-HT3 and 5-HT4 receptors are involved in the emesis induced by the high-dose of cisplatin in Suncus murinus.

Role of 5-HT4 receptors in the mouse passive avoidance test.[Pubmed:9732367]

J Pharmacol Exp Ther. 1998 Sep;286(3):1115-21.

The effects of the administration of different 5-HT4 receptor antagonists (SDZ 205557, GR 125487) and 5-HT4 receptor agonists (BIMU 1, BIMU 8) on memory processes were evaluated in the mouse passive avoidance test. The administration of SDZ 205557 (10 mg kg-1 i.p.) and GR 125487 (10 mg kg-1 i.p.) immediately after termination of the training session produced an amnesic effect. BIMU 1 (20 mg kg-1 i.p.) and BIMU 8 (30 mg kg-1 i.p.), administered 20 min before the training session, prevented the 5-HT4 receptor antagonist-induced amnesia. In the same experimental conditions BIMU 1 (10 mg kg-1 i.p.; 25 microgram/mouse intracerebroventricularly) and BIMU 8 (30 mg kg-1 i.p.; 30 microgram per mouse intracerebroventricularly) prevented scopolamine (1 mg kg-1 i.p.) and dicyclomine (2 mg kg-1 i.p.) amnesia and, at the dose of 10 and 30 mg kg-1 i.p. respectively, prevented amnesia induced by exposure to a hypoxic environment. At the highest effective doses, none of the drugs impaired motor coordination, as revealed by the rota rod test, or modified spontaneous motility and inspection activity, as revealed by the hole board and Animex tests. The 5-HT3 antagonist ondansetron (0.1-1 mg kg-1 i.p.) was unable to prevent scopolamine-, 5-HT4 antagonist- and hypoxia-induced amnesia. These results suggest that the modulation of 5-HT4 receptors plays an important role in the regulation of memory processes. On these bases, the 5-HT4 receptor agonists could be useful in the treatment of cognitive deficits although 5-HT4 receptor antagonists may represent pharmacological tools for investigation of new potential antiamnesic drugs.

Identification of serotonin 5-HT4 recognition sites in the porcine caudate nucleus by radioligand binding.[Pubmed:7984293]

Neuropharmacology. 1994 Mar-Apr;33(3-4):543-9.

Specific binding for the serotonin 5-HT4 receptor (5-HT4R) radioligand [3H]GR 113808 was identified in pig caudate nucleus and characterized by serotonin subtype selective drugs. Binding was inhibited by serotonin and by synthetic indoles, benzamides and benzimidazolones known to characterize the 5-HT4R in functional tests. Rank order of potency of 5-HT4R antagonists was: GR 125487 (Ki, 0.19 nM) > GR 113808 >> SC 53606 > SDZ 205,557 > RS 235971/190 > DAU 6285 > tropisetron > DAU 6215. GR 125487 and GR 113808 were highly selective with respect to the 5-HT3 receptor (5-HT3R). Rank order of potency of 5-HT4R agonists was: SC 53116 (Ki, 21 nM) > BIMU 1 > cisapride > BIMU 8 > serotonin > renzapride > S-zacopride > metoclopramide > R-zacopride > 5-methoxytryptamine >> 5-carboxamidotryptamine. BIMU 8, renzapride, metoclopramide and the zacopride enantiomers gave shallow competition curves. The agonists were substantially less selective than the antagonists with respect to the 5-HT3R. With only two exceptions, SCH 23390 and metergoline, which bound with sub-microM affinity to the 5-HT4R, binding was not inhibited by compounds selective for other G-protein-coupled or channel-gated receptors. Highly significant correlations in affinities of compounds for 5-HT4R in caudata of pigs, guinea pigs and humans were found suggesting no difference among mammalian species.