Studies on the Role of the Preoptic Area in the Control of Reproductive Function in the Rat

Abstract

The effects of bilateral lesions restricted to the medial preoptic area on reproductive function in rats was determined. Adult female rats were placed in a stereotaxic instrument, and bilateral lesions were made in the medial preoptic area of the diencephalon using an anodic current and platinum or stainless steel electrodes. Both types of lesions produced identical effects. Most animals with lesions restricted to the medial preoptic area showed repeated periods of pseudopregnancy for the duration of their lives. Ova were detected in the oviducts on the day of estrus between pseudopregnancies and deciduomata could be produced by uterine traumatization during pseudopregnancy. Daily administration of lergotrile mesylate, a dopamine agonist, for about 2 wk, to the pseudopregnant rats with lesions resulted in the appearance of normal 4 or 5-day estrous cycles. The medial preoptic area apparently may not be necessary for ovulation in the rat, and the normal function of the preoptic area in the contol of reproductive cyclicity may be mediated via dopaminergic neurons. In agreement with earlier studies, it was found that lesions that extended into the anterior hypothalamus resulted in constant estrus.