Selectivity of some ergot derivatives for 5-HT1 and 5-HT2 receptors of rat cerebral cortex.

The affinities of several ergot derivatives for 5-HT1 and 5-HT2 receptors were evaluated using [3H]5-HT and [3H]mianserin, and membranes prepared from rat frontal cortex. CQ 32-084, which had a Ki value against the 5-HT2 component of [3H]mianserin binding of 9 nM, had little effect on [3H]5-HT binding and was selective for the 5-HT2 receptor. Lisuride and LY-158A also displayed preferential affinity for the 5-HT2 receptor. Dihydroergocryptine, CM 29-712, lergotrile and LY-062 were more selective for the 5-HT1 receptor. Bromocriptine showed little selectivity for either subtype. Overall, the ergot derivatives displayed markedly different affinities and selectivities for central 5-HT receptors suggesting that their serotonergic actions should be considered when evaluating their pharmacological spectrum of activity.