Steroid autoradiography of the sexually dimorphic nucleus of the preoptic area.

Autoradiography was performed to determine if the neurons of the sexually dimorphic nucleus of the preoptic area (SDN-POA) in the adult rat accumulate estradiol (E2), testosterone (T), and/or dihydrotestosterone (DHT). Three days prior to steroid administration, adult male and female Sprague-Dawley rats were gonadectomized and adrenalectomized. Animals were then given either [3H]T, [3H]E2, or [3H]DHT through an indwelling jugular cannula. One hour later, animals were decapitated and brain sections processed for thaw mount autoradiography. The autoradiograms which contained the SDN-POA and an adjacent area of the medial preoptic area (MPOA) were quantitatively analyzed using the 3 times background, 5 times background, and Poisson criteria for labeled cells. In general, cells in the SDN-POA and the MPOA accumulate T, E2, or DHT. For both sexes, there is a greater percentage of labeled cells in the SDN-POA than in the MPOA, and a greater percentage of labeled cells following E2 exposure than following T or DHT exposure. In addition, there is a sex difference (male greater than female) in the percentage of labeled cells following T exposure. In summary, these data indicate that adult SDN-POA neurons do accumulate gonadal steroids.