Demonstration of nuclear 3H-estradiol binding in hypothalamus and amygdala of female, androgenized-female, and male rats.

Abstract

The subcellular distribution of radioactivity in female, androgenized female, and male rats 1 hour after the iv administration of tritiated estradiol was examined. High regional specificity among nucle ar fractions of brain areas was seen with the preoptic-anterior hypothal amic area (POA-AH), median eminence-basal hypothalamus (ME-BH), and amygdala having much higher nuclear binding than other brain areas. Nuc lear binding was receptor-mediated in POA-AH, ME-BH, amygdala, dorsal hypothalamus, and the prehypothalamic area in all groups, as demonstrate d by competetive inhibition with diethylstilbestrol (DES). At this time period no differences between male and female rats in DES-blockable radioactivity levels of either nuclear or supernatant fractions in any brain area or pituitary were observed. Androgenized females had lower DES-blockable, nuclear radioactivity levels in POA-AH, ME-BH, and uteri but the % of total tissue radioactivity in the nuclei did not differ between groups for any tissue. These results demonstrate that males and females have similar estradiol uptake systems that are capable of high levels of nuclear binding in various brain areas.