RESEARCH INTERESTS: My research program investigates the neuroendocrine control of male rat sexual behavior. We have shown that dopamine is released in the medial preoptic area (MPOA) as soon as a male rat encounters a receptive female; release is further increased during copulation. Stimulation of dopamine receptors in the MPOA controls genital reflexes and sexual motivation. This brain area is essential for male sexual behavior in all vertebrate species that have been studied, from fish through humans. Testosterone promotes copulation, in part, by up-regulating nitric oxide synthase in the MPOA; the resultant production of nitric oxide increases both basal and female-stimulated dopamine release. We have also shown that serotonin is released in the anterior lateral hypothalamus at the time of ejaculation and contributes to the postejaculatory sexual quiescence, in part by decreasing mesolimbic dopamine release. Recent research centers on the roles of dopamine and glutamate in the increase in sexual proficiency due to sexual experience. Similar mechanisms may underlie other forms of memory and drug addiction. Finally, we are interested in how the circuitry underlying sexual behavior is integrated with that subserving other motivated behaviors.