Uptake and retention of tritiated estradiol in brain and peripheral tissues of male, female and neonatally androgenized female rats

Male and female rats respond differently to estrogen treatment in terms of the elicitation of mating responses. It was hypothesized that this differential behavioral response may reflect a differential accumulation and/or retention of estrogen in those neural cells which mediate behavior. To test this hypothesis, male, female and neonatally androgen-treated female rats, gonadectomized in adulthood, were administered tritiated estradiol iv and were sacrificed 5, 30 or 60 min later. Radioactivity levels were assessed in the following samples: brain-hypothalamus, preoptic-diagonal band region and cortex; pituitary, muscle and uterus. All tissues exhibited an accumulation of radioactivity. Except for pituitary, all tissue showed decreasing radioactivity with time after treatment. Except for cortex, males exhibited lower radioactivity levels than females. Males, however, weighed more than females at the time of treatment. Therefore, similar procedures were followed in a second experiment in which males and fem...