Hormonal, Experiential, and Neural Regulation of Ventromedial Hypothalamic Glutamate in the Female Rat

Hormonal, Experiential, and Neural Regulation of Ventromedial Hypothalamic Glutamate in the Female Rat Michaela Georgescu, PhD Concordia University, 2010 Previous experiments have shown that enhanced glutamate neurotransmission in the ventromedial hypothalamus by administration of glutamate or its selective receptor agonists kainate, N-methyl-D-aspartic acid or a-amino-3-hydroxyl-5methyl-4-isoxazole-propionate (AMPA), results in a pronounced inhibition of proceptive and consummatory sexual behaviors. The five chapters encompassing this thesis were designed to expand our comprehension of the role that ventromedial hypothalamic glutamate plays in the control of sexual behavior in the female rat. The experiment presented in Chapter 1 shows that a substantial proportion of the neurons activated in the ventromedial hypothalamus by vaginocervical stimulation are glutamatergic, and that priming with estradiol benzoate and progesterone inhibits this activation. Chapter 2 investigated the effect of 6,7-Dinitroquinoxaline-2,3-dione (DNQX), a glutamate antagonist, on estrus termination, when infused in the ventromedial hypothalamus of female rats. DNQX effectively reversed the effect of vaginocervical stimulation on appetitive behaviors, lordosis quotient and lordosis magnitude, but had no effect on pacing, defensive behaviors, or male ejaculations. These results suggest that blocking glutamate transmission at the AMPA/kainate receptor delays onset of