Presynaptic muscarinic receptor activation enhances striatal dopamine release evoked by depolarization but not that induced by non-depolarizing stimuli.
The release of [(3)H]dopamine stimulated by depolarization with 15 mM KCl of superfused rat striatal synaptosomes was potentiated by acetylcholine through the activation of presynaptic muscarinic receptors. In contrast, acetylcholine did not potentiate the release of [(3)H]dopamine elicited by d-amphetamine nor that caused by the calcium ionophore A23187. The dopamine carrier blocker nomifensine prevented the releasing action of amphetamine but not that of acetylcholine. The results suggest that the activation of muscarinic receptors on dopamine terminals in the rat corpus striatum selectively affects the calcium-dependent depolarization-induced release of the [(3)H]catecholamine. Moreover, the [(3)H]dopamine release caused by acetylcholine seems to occur independently of the membrane dopamine carrier.
Marchi
M
M
Instituto de Farmacologia e Farmacognosia, Università degli Studi di Genova, Viale Cembrano 4, 16148 Genova, Italy.
Paudice
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P
Bonanno
G
G
Raiteri
M
M