General pharmacology of ergot alkaloids.

Ergot alkaloids possess a wide and divergent spectrum of central and peripheral pharmacodynamic actions. They interfere with different receptor sites to stimulate and/or inhibit effector structures. The concept of partial agonism on alpha-adrenoreceptors has replaced the ancient hypothesis of direct stimulation of vascular and uterine smooth muscle. The mechanisms which are considered to be relevant for the therapeutic use of dihydroergotamine, a potent drug increasing venous tone, and of bromocriptine, a specific inhibitor of prolactin secretion, are discussed in more detail.