Effect of cholecystokinin-octapeptide on dopamine release from slices of cat caudate nucleus.
The cat caudate nucleus has been reported to possess a rich and fairly even distribution of nerve endings, containing both dopamine- and cholecystokinin-like peptides. In this study, the effect of cholecystokinin-octapeptide (CCK-8) on basal and electrically evoked tritium outflow from slices of cat caudate nucleus previously labeled with [3H]dopamine was examined. Evoked tritium outflow from slices of cat caudate nucleus was Ca2+ dependent and abolished by tetrodotoxin, suggesting that it reflects action potential-induced [3H]dopamine release. In the presence of bovine serum albumin and bacitracin, the sulfated but not the unsulfated form of CCK-8 inhibited both basal and electrically evoked tritium outflow from slices of cat caudate nucleus at very low concentrations. CCK-8 sulfate was efficient in causing this effect in concentrations down to 10(-14) M, and the maximum effect was obtained with 10(-11) M. In contrast, without bovine serum albumin and bacitracin, no inhibitory effect of CCK-8 sulfate was seen, but instead, a marked enhancement of tritium outflow at 10(-7) M was observed. The findings suggest that CCK-8 sulfate in dopamine/CCK coexistence regions is involved in regulating dopamine release.
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D002415:Cats; D002421:Caudate Nucleus / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D004298:Dopamine / Q000378:metabolism*; D004558:Electric Stimulation; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D012844:Sincalide / Q000494:pharmacology*; D013779:Tetrodotoxin / Q000494:pharmacology; D014316:Tritium
D014316:Tritium; D013779:Tetrodotoxin; D012844:Sincalide; D001058:Apomorphine; D004298:Dopamine