Stimulatory Action of Lisuride on Dopamine-Sensitive Adenylate Cyclase in the Rat Striatal Homogenate

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Abstract
The effect of lisuride, an ergot derivative of isolysergic structure, on dopamine-sensitive adenylate cyclase was studied in the homogenate of rat corpus striatum. Stimulatory action of lisuride, similar to the actions of dopamine and apomorphine, on striatal adenylate cyclase was potentiated significantly by GTP and by guanyl-5''-yl imidodiphosphate (GMP-PNP) but with lisuride alone, there was only a slight stimulation. The maximal stimulation attained in the presence of GTP corresponded to .apprx. 1.4 times the basal rate of cAMP formation in the homogenate and was abolished by an addition of haloperidol. Lisuride at a concentration > 3 .mu.M inhibited stimulation of cAMP formation by dopamine. The effect of lisuride and the extent of potentiation by the guanyl nucleotides were comparable to the effects of apomorphine, under corresponding conditions. Lisuride, like apomorphine, acts as a partial agonist-antagonist and has the ability to stimulate the dopamine-sensitive adenylate cyclase in the rat corpus striatum.
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