Increase by 5-hydroxykynuramine of spontaneous acetylcholine release from myenteric neurons: mediated by serotonin M receptors.
The effects of 5-hydroxykynuramine (5-OH-K) and of 3-(2-amino-5-hydroxyphenyl)-propaneamine (AHPP) on spontaneous and electrically evoked release of [3H]acetylcholine were studied in the guinea-pig myenteric plexus longitudinal muscle preparation preincubated with [3H]choline. 5-OH-K caused a concentration-dependent increase in spontaneous [3H]acetylcholine release (EC50 5.3 microM). This effect was diminished in the presence of a desensitizing concentration of 5-hydroxytryptamine (5-HT). AHPP (1-100 microM) did not affect the spontaneous outflow of [3H]acetylcholine. The electrically evoked release of [3H]acetylcholine was significantly reduced in the presence of 100 microM of either 5-OH-K or AHPP. Metitepine did not antagonize the inhibition, which suggests that 100 microM of either compound non-specifically depressed the evoked release. It is concluded that 5-OH-K is inactive at the release-inhibitory 5-HT1 receptor, but is a potent agonist at the M receptor of myenteric neurons.
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007735:Kynuramine / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008297:Male; D008719:Methiothepin / Q000494:pharmacology; D009197:Myenteric Plexus / Q000187:drug effects* / Q000378:metabolism; D011427:Propiophenones / Q000494:pharmacology*; D011437:Propylamines / Q000494:pharmacology; D011985:Receptors, Serotonin / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology
D011427:Propiophenones; D011437:Propylamines; D011985:Receptors, Serotonin; D012701:Serotonin; D007735:Kynuramine; D008719:Methiothepin; C001402:5-hydroxykynuramine; C052917:4-amino-3-(3-aminopropyl)phenol; D000109:Acetylcholine