Regulation by the medial amygdala of copulation and medial preoptic dopamine release.

The medial preoptic area (MPOA) is a critical integrative site for male copulatory behavior in most vertebrate species. Extracellular dopamine (DA) is increased in the MPOA of male rats immediately before and during copulation. DA agonists microinjected into the MPOA of male rats facilitate and DA antagonists inhibit sexual behavior. A major source of input to the MPOA is the medial amygdala (MeA), which processes and relays olfactory information to the MPOA. We now report that microinjections of a DA agonist into the MPOA of animals with excitotoxic lesions of the amygdala restored copulatory ability that was lost after the lesions. Moreover, radio-frequency lesions of the MeA impaired copulation and blocked the increases in extracellular DA seen in animals with sham lesions during exposure to a receptive female and during copulation. Thus, both copulatory ability and the MPOA DA response, during exposure to a receptive female and during copulation, are facilitated by input from the MeA to the MPOA.