Myoclonus in guniea pigs is induced by indole-containing but not piperazine-containing 5HT agonists.
L-5-Hydroxytryptophan (5HTP) induces in guinea pigs a myoclonic jerking which is dependent upon stimulation of brainstem 5-hydroxytryptamine (5HT) receptors. We have investigated the ability of 5HT precursors and a range of synthetic 5HT agonists to produce myoclonus. The 5HT precursors and 5HT agonists containing an indole nucleus induced dose-dependent jerking in guinea pigs. In contrast, 5HT agonists possessing a piperazine moiety induced occasional jerking only at toxic doses, but not a those doses normally associated with 5HT agonist activity. The difference in activity between the indole-containing compounds and piperazine-containing 5HT agonists suggests that myoclonus is due to activation of an indole-selective brainstem 5HT receptor and provides further evidence for multiple cerebral 5HT receptors.
D000818:Animals; D001933:Brain Stem / Q000187:drug effects; D005260:Female; D006168:Guinea Pigs; D007211:Indoles / Q000494:pharmacology*; D009207:Myoclonus / Q000139:chemically induced / Q000503:physiopathology*; D011814:Quipazine / Q000031:analogs & derivatives / Q000494:pharmacology; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology; D012701:Serotonin / Q000031:analogs & derivatives* / Q000494:pharmacology; D013329:Structure-Activity Relationship; D014363:Tryptamines / Q000494:pharmacology; D014364:Tryptophan / Q000494:pharmacology
D007211:Indoles; D011985:Receptors, Serotonin; D014363:Tryptamines; D012701:Serotonin; C030820:tryptamine; D011814:Quipazine; D014364:Tryptophan