5-hydroxytryptophan-induced myoclonus in guinea pigs. A physiological and pharmacological investigations.
5-Hydroxytryptophan (5-HTP) induces a characteristic behavioural syndrome of altered motor activity with muscle jerking in guinea pigs. Myoclonic jerking occurs synchronously in forelimbs and hindlimbs and is associated with a stereotyped electromyographic (EMG) pattern of a burst of activity lasting 40-50 msec in active muscles, followed by silence lasting 50-70 msec, followed by a further variable period of muscle activity. Such myoclonus may be induced also by the administration of L-tryptophan plus a monamine oxidase inhibitor (MAOI), or by agents acting as serotonin (5-HT) receptor agonists. The 5-HTP-induced syndrome is antagonised by a central decarboxylase inhibitor (NSD-1035) and by agents which block 5-HT receptors (methysergide and cyproheptadine). 5-HTP-induced jerking is abolished below the level of a spinal cord transection, but persists in decerebrate animals. No electroencephalographic (EEG) changes are seen preceding the muscle jerks. The clinical significance of this animal model of myoclonus is discussed.
D006916:5-Hydroxytryptophan / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000818:Animals; D003533:Cyproheptadine / Q000494:pharmacology; D004576:Electromyography; D005260:Female; D006168:Guinea Pigs; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009132:Muscles / Q000187:drug effects; D009207:Myoclonus / Q000139:chemically induced* / Q000503:physiopathology; D010293:Pargyline / Q000494:pharmacology; D014364:Tryptophan / Q000494:pharmacology
D003533:Cyproheptadine; D014364:Tryptophan; D010293:Pargyline; D006916:5-Hydroxytryptophan