Neurochemical effects of some ergot derivatives: a basis for their antiparkinson actions.

Bromocriptine and the two ergoline derivatives, CQ 32-084 and CM 29-712, exert dopamine-like effects in experimental models and have been shown to possess antiparkinsonian activity. Biochemical investigations indicate that they differ in their specificity towards the different dopamine receptor types and, in addition, interact with other neurotransmitter receptors. Bromocriptine appears to be a potent agonist at D2-receptors. Furthermore, it blocks adenylate cyclase coupled serotonin receptors and antagonizes central alpha-adrenergic receptors. The two ergoline derivatives are multiple agonists. CQ 32-084 stimulates both D1- and D2-, and CM 29-712 only D1-receptors. In addition, both compounds stimulate adenylate cyclase coupled serotonin receptors and antagonize central alpha-adrenergic receptors.