Cholecystokinin [corrected] octapeptide modulates dopamine release in rat striatum

Abstract

The effect of cholecystokinin octapeptide sulfated (CCK8S) on the basal and electrically evoked release of [3H]dopamine ([3H]DA) in striatal slices from the rat brain was studied. Cholecystokinin octapeptide did not influence the basal release of [3H]DA. Field electrical stimulation (FES) (2 Hz) induced an increase of dopamine release from striatal slices, which was Ca2+ dependent and was abolished by tetrodotoxin, 10(-6) M. Cholecystokinin octapeptide (10(-9) M, 10(-8) M and 10(-7) M) dose dependently reduced the electrically evoked release of [3H]DA. This effect was antagonized by the CCK-A receptor antagonists loxiglumide (10(-7) M, 10(-6) M and 10(-5) M) or proglumide (10(-5) M, 10(-4) M and 10(-3) M). The results suggest that CCK receptors type A are involved in this effect of CCK8S in the striatum.