Sex differences in the distribution of androgen receptors in the human hypothalamus

The present study reports for the first time the distribution of androgen r eceptor immunoreactivity (AR-ir) in the human hypothalamus of ten human sub jects (five men and five women) ranging in age between 20 years and 39 year s using the antibody PG21. Prolonged postmortem delay (72:00 hours) or fixa tion time (100 days) did not influence the AR-ir. In men, intense nuclear A R-ir was found in neurons of the horizontal limb of the diagonal band of Br oca. in neurons of the lateromamillary nucleus (LMN), and in the medial mam illary nucleus (MMN). An intermediate nuclear staining was found in the dia gonal band of Broca, sexually dimorphic nucleus of the preoptic area, parav entricular nucleus, suprachiasmatic nucleus, ventromedial nucleus, and infu ndibular nucleus, whereas weaker labeling was found in the bed nucleus of t he stria terminalis, medial preoptic area, dorsal and ventral zones of the periventricular nucleus, supraoptic nucleus, and nucleus basalis of Meynert . In most brain areas, women revealed less staining than men. In the LMN an d the MMN, a strong sex difference was found. Cytoplasmic labeling was obse rved in neurons of both sexes, although women showed a higher variability i n the intensity of such staining. However, no sex differences in AR-ir were observed in the bed nucleus of the stria terminalis, the nucleus basalis o f Meynert, or the islands of Calleja. Species differences and similarities of the AR-ir distribution are discussed. The present results suggest the pa rticipation of androgens in the regulation of various hypothalamic processe s that are sexually dimorphic. J. Comp. Neurol. 425:422-435, 2000. (C) 2000 Wiley-Liss, Inc.