Effects of ergot drugs on serotonergic function: behavior and neurochemistry.

Several new ergot drugs were tested for behavioral and neurochemical effects related to serotonergic function. Lergotrile and bromocriptine potentiated the so-called "5-HT syndrome", a set of behaviours associated with increased serotonergic neurotransmission consequent to monoamine oxidase inhibition and tryptophan loading. Metergoline antagonized this behavior. In studies of receptor binding using 3H-5-HT or 3H-LSD, metergoline was the most potent at displacing specific ligand binding. Since the ergots also affect dopaminergic function, these results are discussed for their information on both dopaminergic and serotonergic actions of these drugs and their implications for clinical use of ergots.