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Dual effects of 5‐hydroxytryptamine on the release of γ‐aminobutyric acid from myenteric neurones of the guinea‐pig ileum
Author(s) -
Shirakawa Junji,
Takeda Koichiro,
Taniyama Kohtaro,
Tanaka Chikako
Publication year - 1989
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.1476-5381.1989.tb12601.x
Subject(s) - methysergide , ketanserin , myenteric plexus , tetrodotoxin , inhibitory postsynaptic potential , serotonin , 5 ht receptor , chemistry , serotonergic , ileum , guinea pig , medicine , endocrinology , gabaergic , receptor , pharmacology , biology , biochemistry , immunohistochemistry
The effects of 5‐hydroxytryptamine (5‐HT) on the release of γ‐aminobutyric acid (GABA) were examined in the longitudinal muscle‐myenteric plexus (LM‐MP) preparation of guinea‐pig ileum. 5‐HT increased the spontaneous release and inhibited the electrically‐evoked release of [ 3 H]‐GABA. The 5‐HT‐evoked release was Ca 2+ ‐dependent and tetrodotoxin‐sensitive, and was antagonized by (3α‐tropanyl)‐1H‐indole‐3‐carboxylic acid ester (ICS 205–930), but not by methysergide and ketanserin. The inhibitory effect of 5‐HT was antagonized by methysergide, but not by ketanserin and ICS 205–930. 8‐Hydroxy‐2‐(di‐ n ‐propylamino)tetralin mimicked the inhibitory effect of 5‐HT. Thus, 5‐HT may exert an excitatory effect on the enteric GABAergic neurone via the 5‐HT 3 receptor and an inhibitory effect via the 5‐HT 1A receptor.