Cholecystokinin-8 increases K(+)-evoked [3H] gamma-aminobutyric acid release in slices from various brain areas.
[3H] gamma-Aminobutyric acid (GABA) release was studied in rat brain slices in the absence or presence of cholecystokinin-8 (CCK-8). [3H]GABA release under the conditions used was Ca(2+)-dependent and insensitive to the presence of the glial uptake blocker beta-alanine. While the basal release of [3H]GABA was not affected by CCK-8, the K(+)-stimulated release of [3H]GABA was significantly enhanced by 300 nM of CCK-8 in the caudate putamen, the substantia nigra, the hippocampal formation and the parietofrontal cortex. In the cerebral cortex the CCK-8 enhancement of [3H]GABA release was concentration-dependent and abolished by the CCKB receptor antagonists PD135,158 (1.0 nM) and L-365,260 (100 nM). A significant counteraction of the CCK-8 action was also found with the CCKA receptor antagonist L-364,718 (100 nM) but only in concentrations at which both CCKA and CCKB receptors are blocked. No CCK-8 effects on [3H]GABA release were observed when tetrodotoxin was superfused 5 min before the K(+)-induced [3H]GABA release. It is suggested that the enhancing actions of CCK-8 on K(+)-stimulated [3H]GABA release is mainly related to an activation of CCKB receptors.
Pérez de la Mora
M
M
Departamento de Neurosciencias, Universidad Nacional Autonoma de México, D.F., Mexico.
Hernandez-Gómez
A M
AM
Méndez-Franco
J
J
Fuxe
K
K
D000818:Animals; D001570:Benzodiazepinones / Q000494:pharmacology; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D020109:Devazepide; D004305:Dose-Response Relationship, Drug; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008536:Meglumine / Q000031:analogs & derivatives / Q000494:pharmacology; D010671:Phenylurea Compounds; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011949:Receptors, Cholecystokinin / Q000037:antagonists & inhibitors*; D012844:Sincalide / Q000494:pharmacology*; D015091:beta-Alanine / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D001570:Benzodiazepinones; D007211:Indoles; D010671:Phenylurea Compounds; D011949:Receptors, Cholecystokinin; D015091:beta-Alanine; C065600:PD 135158; C058121:L 365260; D005680:gamma-Aminobutyric Acid; D008536:Meglumine; D020109:Devazepide; D012844:Sincalide; D011188:Potassium; D002118:Calcium