Endogenous inhibitors of picrotoxinin-convulsant binding sites in rat brain.
The binding of [3H]-alpha-dihydropicrotoxinin (DHP) to rat brain membranes was inhibited by aqueous extracts of the same tissue, as well as by several naturally occurring substances such as pyrimidines, purines, and their metabolites. The 200 000 X g supernatant fraction of cortex homogenates inhibited DHP binding competitively, reversibly, without preincubation, at 0 degrees C, with 40 microgram protein inhibiting 50%. Compounds such as adenine, hypoxanthine, inosine, cytosine, allantoin and uric acid at about 0.1 mM also inhibited DHP binding competitively, suggesting a relationship between DHP binding sites, benzodiazepine binding sites, and GABA receptor binding sites.
D000818:Animals; D000927:Anticonvulsants / Q000302:isolation & purification; D001569:Benzodiazepines / Q000378:metabolism; D001665:Binding Sites; D001667:Binding, Competitive; D001923:Brain Chemistry; D002540:Cerebral Cortex / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D010852:Picrotoxin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011687:Purines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D051381:Rats; D014020:Tissue Extracts / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D000927:Anticonvulsants; D001569:Benzodiazepines; D010852:Picrotoxin; D011687:Purines; D011743:Pyrimidines; D014020:Tissue Extracts; D005680:gamma-Aminobutyric Acid