CONTROL OF GONADOTROPIN FEEDBACK - THE POSSIBLE ROLE OF ESTROGEN-INDUCED HYPOTHALAMIC SYNAPTIC PLASTICITY

The preovulatory gonadotropin surge is a critical event in reproductio n. Although many explanations have been given for the inhibition-disin hibition cycle referred to as positive feedback, none are completely s atisfactory. Recent evidence indicates that the preovulatory surge of gonadotropin is induced, in part, by the disengagement of inhibitory s ynaptic connections in the hypothalamic arcuate nucleus. This disinhib ition of gonadotropin-releasing hormone secretion results in a massive release by the estrogen-sensitized pituitary gonadotrophs. Investigat ions are presently under way to determine whether other areas of the h ypothalamus are involved in this estrogen-induced synaptic plasticity.