Eleven ergot compounds were competed against [3H]-ketanserin-labelled 5-HT2 receptors in rat and human cortex. Four of the ergots are selective for rat 5-HT2 receptors--mesulergine, methysergide, nicergoline and metergoline, whereas pergolide, d-lysergic acid, ergonovine, ergotamine, d-lysergic acid diethylamide, lisuride and dihydroergotamine display selectivity for human 5-HT2 receptors....