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On the nature of the 5‐HT receptor subtype inhibiting acetylcholine release in the guinea‐pig ileum
Author(s) -
Ramírez M.J.,
Río J.,
Cenarruzabeitia E.,
Lasheras B.
Publication year - 1994
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1994.tb16176.x
Subject(s) - methysergide , agonist , medicine , endocrinology , acetylcholine , myenteric plexus , chemistry , receptor antagonist , tachykinin receptor , receptor , biology , pharmacology , serotonin , substance p , antagonist , neuropeptide , immunohistochemistry
1 The nature of the 5‐hydroxytryptamine (5‐HT) receptor subtype controlling acetylcholine release and contraction induced by stimulation of the neurokinin NK 3 receptor has been studied in the longitudinal muscle‐myenteric plexus preparation from guinea‐pig ileum. 2 In preparations preloaded with [ 3 H]‐choline, the selective NK 3 agonist, senktide, produced a concentration‐dependent increase in tritium overflow, an index of [ 3 H]‐acetylcholine release. Low concentrations of neurokinin B, also markedly increased tritium efflux. 3 The senktide‐induced acetylcholine release was markedly increased by the same concentration of methysergide and mesulergine. The 5‐HT 2A/2C agonist DOI (1 μ m ) inhibited the tritium overflow while 8‐OH‐DPAT, sumatriptan and ketanserin (1 μ m each) were without effect on the senktide‐induced tritium efflux. 4 The contractile response to senktide in the guinea‐pig ileum was attenuated by atropine, 0.1 μ m . Methysergide, a 5‐HT 1/2 receptor antagonist, and mesulergine, a 5‐HT 2A/2B/2C receptor antagonist, (1 μ m each), enhanced the contractile effect of the NK 3 receptor agonist. 5 It is concluded that the acetylcholine release induced by a NK 3 receptor agonist is inhibited by stimulation of a 5‐HT receptor, possibly of the 5‐HT 2C or 5‐HT 2B subtype.