CAPTOPRIL INHIBITS BOTH DOPAMINERGIC AND CHOLINERGIC NEUROTRANSMISSION IN THE CENTRAL, NERVOUS-SYSTEM

1. The present study was performed to investigate the effects of capto pril on both dopaminergic and cholinergic neurotransmission in the rat central nervous system. 2, Slices of rat striatum were prepared and p relabelled with [H-3]-dopamine or [H-3]-choline, Slices were continuou sly superfused with Krebs'-Ringer solution and electrical stimulation (1 Hz) was performed. 3. Captopril significantly inhibited stimulation -evoked [H-3]-dopamine release from rat striatal slices in a concentra tion-dependent manner (S2/S1 ratios: control 0.835+/-0.018 (n = 6); 1 x 10(-5) mol/L captopril 0.597+/-0.035 (n=6; P<0.05); 5 x 10(-5) mol/L captopril 0.561+/-0.041 (n = 6; P<0.05)). How ever, the basal release of [3H]-dopamine was not affected by captopril, 4, Captopril also red uced stimulation-evoked [H-3]-acetylcholine release in the striatum (S 2/S1 ratios: control 0.891+/-0.016 (n=6); 1 x 10(-5) mol/L captopril 0 .794+/-0.011 (n = 6; P<0.05)), 5, These results show that captopril in hibits the release of both dopamine and acetylcholine in the rat stria tum, Although the mechanisms underlying the neurosuppressive effects o f captopril remain to be determined, the findings suggest that the inh ibition of dopaminergic and cholinergic neurotransmission may be relat ed to the central action of the angiotensin-converting enzyme inhibito r.