Role of glutamate receptors in the ventromedial hypothalamus in the regulation of female rat sexual behaviors I. Behavioral effects of glutamate and its selective receptor agonists AMPA, NMDA and kainate.

Bilateral infusions of glutamate or kainate to the ventromedial hypothalamus (VMH) have been shown previously to produce a rapid inhibition of lordosis in estrogen-primed female rats induced by manual flank stimulation. The present study examined whether glutamate or selective ionotrophic glutamate receptor agonists can disrupt appetitive and consummatory sexual behaviors following bilateral infusions to the VMH of females during copulation with male rats. Ovariectomized, sexually experienced female rats were implanted bilaterally with guide cannulae aimed at the ventrolateral VMH. After recovery from surgery, females were primed with estradiol benzoate and progesterone and infused with different doses of glutamate, AMPA, NMDA or kainate (n=9-10 in each dose group) 3 min prior to a test with sexually vigorous males in bilevel chambers. Glutamate infusions decreased the display of hops and darts and produced a trend toward decreased lordosis. AMPA infusions decreased the display of solicitations, hops and darts, and lordosis. NMDA infusions decreased lordosis and increased defensive behaviors and pacing. Kainate infusions decreased solicitations, hops and darts, and lordosis, and increased defensive behaviors and pacing. These data indicate that the activation of glutamate receptors in the VMH is inhibitory for both appetitive and consummatory aspects of sexual behavior in the female rat.