Dual effects of 5-hydroxytryptamine on the release of gamma-aminobutyric acid from myenteric neurones of the guinea-pig ileum.
The effects of 5-hydroxytryptamine (5-HT) on the release of gamma-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 [3H]-GABA. The 5-HT-evoked release was Ca2+-dependent and tetrodotoxin-sensitive, and was antagonized by (3 alpha-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-HT3 receptor and an inhibitory effect via the 5-HT1A receptor.
Shirakawa
J
J
Department of Pharmacology, Kobe University School of Medicine, Japan.
Takeda
K
K
Taniyama
K
K
Tanaka
C
C
D000818:Animals; D004558:Electric Stimulation; D006168:Guinea Pigs; D007082:Ileum / Q000294:innervation / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009197:Myenteric Plexus / Q000166:cytology / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D012701:Serotonin / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D012701:Serotonin; D005680:gamma-Aminobutyric Acid