A functional interaction between GABA and 5-HT in inhibiting picrotoxin-induced myoclonus in rats.
Pretreatment with 5-hydroxytryptophan (5-HTP), a precursor of 5-HT, antagonised while pretreatment with p-chlorophenylalanine (PCPA), a 5-HT depletor, potentiated the myoclonus induced by picrotoxin, a GABA antagonist. Pretreatment with aminooxyacetic acid (AOAA), a GABA transaminase inhibitor, antagonised picrotoxin-induced myoclonus. The combined effect of the least protective doses of AOAA and 5-HTP was greater than the sum of their individual inhibitory effects on picrotoxin-induced myoclonus. Further, AOAA failed to inhibit picrotoxin-induced myoclonus in PCPA pretreated rats. These findings suggest that the central 5-HT-ergic system exerts a facilitatory influence on the GABA-ergic system and thus it is involved in the antimyoclonic action of GABA.
Paul
V
V
Department of Pharmacology & Environmental Toxicology, Dr. A. L. M. Postgraduate Institute of Basic Medical Sciences, University of Madras, Taramani.
Krishnamoorthy
M S
MS
D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000625:Aminooxyacetic Acid / Q000494:pharmacology; D000818:Animals; D010134:Fenclonine / Q000494:pharmacology; D008297:Male; D009207:Myoclonus / Q000139:chemically induced* / Q000503:physiopathology; D010852:Picrotoxin / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D006916:5-Hydroxytryptophan; D000625:Aminooxyacetic Acid; D010134:Fenclonine; D010852:Picrotoxin; D012701:Serotonin; D005680:gamma-Aminobutyric Acid