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Release of γ‐aminobutyric acid and acetylcholine by neurotensin in guinea‐pig ileum
Author(s) -
Nakamoto Mitsuharu,
Tanaka Chikako,
Taniyama Kohtaro
Publication year - 1987
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.1476-5381.1987.tb11204.x
Subject(s) - neurotensin , hexamethonium , tetrodotoxin , acetylcholine , endocrinology , medicine , neuropeptide , substance p , neurotensin receptor , chemistry , neurotransmitter , biology , receptor , biochemistry , central nervous system
1 The release of γ‐aminobutyric acid (GABA) and acetylcholine (ACh) from the strips of guinea‐pig ileum was investigated in the presence of neurotensin. 2 Neurotensin evoked the release of [ 3 H]‐GABA from the strips preloaded with [ 3 H]‐GABA, and the evoked release was Ca 2+ ‐dependent and tetrodotoxin‐sensitive. 3 Hexamethonium, scopolamine, [D‐Pro 2 , d ‐Trp 7,9 ] substance P and pretreatment with substance P did not alter the neurotensin‐evoked release of [ 3 H]‐GABA. 4 Pretreatment with neurotensin inhibited the release of [ 3 H]‐GABA evoked by neurotensin but not by high K + , thereby indicating that neurotensin induced a specific desensitization of its own receptor. These observations indicate that neurotensin may stimulate the GABAergic neurone through its own receptor. 5 Neurotensin evoked the release of [ 3 H]‐ACh from strips preloaded with [ 3 H]‐choline and this release was Ca 2+ ‐dependent and tetrodotoxin‐sensitive. 6 The evoked release of [ 3 H]‐ACh was not affected by hexamethonium, scopolamine and [D‐Pro 2 , d ‐Trp 7,9 ] substance P. 7 Bicuculline partly inhibited the neurotensin‐evoked release of [ 3 H]‐ACh; thus neurotensin seems to induce a release of ACh partly through the release of endogenous GABA. 8 All this evidence indicates that neurotensin induces release of GABA as well as ACh from the myenteric neurones of the guinea‐pig ileum.