Serotonin involvement in lisuride-induced mounting and in sleep.

Mounting behavior of rats induced by several drugs, such as e.g. p-CPA, 5,7-dihydroxytryptamine, L-DOPA or lisuride, appears to result from a combined decrease of 5-hydroxytryptamine (5-HT) and increase of dopamine (DA) neurotransmission. In this paper, lisuride-induced mounting is proposed as a behavioral model for detecting pharmacologically active drugs that interact with monoaminergic mechanisms, e.g. 5-HT reuptake blockers and type A monoamine oxidase inhibitors. With regard to sleep, 5-HT appears to sustain a relevant part in controlling the sleep-wakefulness cycle. However, other transmitters or neuromodulators (catecholamines, oligopeptides etc.) may also be involved in sleep mechanisms.