BRAIN MONOAMINERGIC NEUROTRANSMISSION IN THE MEDIATION OF LORDOSIS BEHAVIOR IN THE FEMALE RAT

The present paper reviews recent pharmacological evidence indicating an important role for central monoaminergic neurotransmission in the mediation of lordosis behavior in the female rat. Following the initial observations by Meyerson and his colleagues in the early 1960s, demonstrating an inhibitory serotonergic mechanism, continued studies have identified 5-hydroxytryptamine (5-HT) 5-HT1A receptors to be of particular importance. Stimulation of central 5-HT2 receptors appear to have an opposite role, i.e. facilitating the elicitation of the lordosis response. As regards brain dopaminergic neurotransmission, it appears that brain dopamine (DA) D2 receptors mediate an inhibitory effect on the lordosis behavior, whereas no distinct role has been ascribed to DA D1 receptors. The serotonergic and the dopaminergic mechanisms can be manipulated independently, perhaps indicating the operation of parallel mechanisms. Most of the evidence presented above has been obtained in experiments on ovariectomized female rats primed with subthreshold doses of estrogen. It appears, however, that at least the inhibitory effects mediated by serotonergic neurotransmission are not dependent on the presence of progesterone.