Sex differences in cytosolic progestin receptors in microdissected regions of the hypothalamus/preoptic area of guinea pigs

Abstract

Cytosolic progestin receptors (CPRS) were measured in microdissected nuclei of the hypothalamus and preoptic area of male and female guinea pigs. Adult gonadectomized animals were given 3 daily injections of 20 μg/day estradiol benzoate (EB) or oil vehicle. 24 h later, animals were sacrificed and cytosolic progestin receptors were measured using the synthetic progestin 3H-R5020. CPR levels did not differ significantly between oil treated females in any barin areas examined. With EB treatment, males showed significant increases in CPRs inmost of the brain areas in which females showed increases, i.e. in the medial preoptic area, the periventricular part of the preoptic area, the periventricular part of the anterior hypothalamus, the ventromedial nucleus of the hypothalamus, the periventricular part of the medial hypothalamus and the arcuate-median eminence. However, EB treated males showed significantly lower CPR levels than EB treated females in both the periventricular part of the preoptic area and the periventricular part of the medial hypothalamus.