Direct evidence for the stimulation of rabbit retina dopamine receptors by ergot alkaloids

The effects of three ergot alkaloids on cyclic AMP concentrations in isolated retinae of the rabbit were investigated. Significant increases in cyclic AMP concentration were found after a 10 min exposure to 1 microM ergometrine or agroclavine. The increases in cyclic AMP elicited by ergometrine, agroclavine or 2-bromo-alpha-ergocryptine (CB-154), at 100 microM concentrations, were comparable to those seen after dopamine or the dopamine-like drug, apomorphine. Furthermore, the effects of the ergot alkaloids were blocked by the specific dopamine receptor blocking agent, fluphenazine. It is concluded that some ergot alkaloids or their derivatives are potential dopamine-mimetic drugs.