CONVERSION OF TESTOSTERONE INTO 5α-REDUCED METABOLITES IN THE ANTERIOR PITUITARY AND IN THE BRAIN OF MATURING RATS

Abstract

The anterior pituitary of normal female rats shows a considerable 5α-reductase activity. Such an activity is higher in the very first days of life and decreases from birth until the 28th day of age. The anterior pituitary of normal male rats also shows 5α-reductase activity, but this is smaller than that of the anterior pituitary of female animals. Significant differences between activities present in the two sexes can be observed from birth until the 21st day of age. A slight difference in the 5α-reductase activity of the hypothalami of maturing male and female animals has also been observed. As previously stated, the 5α-reductase activity of the anterior pituitary of female rats is much higher than that of male animals on day 14 of life. Castration performed on neonatal male rats brings about an increase in the 5α-reductase activity of their anterior pituitaries evaluated on day 14 of age. The levels of the enzyme become very similar to those found in the anterior pituitary of normal females of the same age. Conversely, the neonatal administration of testosterone propionate to female rats induces a decrease of the 5α-reductase activity of their pituitaries measured on day 14 of life. Such an activity becomes very similar to that of normal males of the same age. Analogous variations, although of a smaller magnitude, have been observed at hypothalamic level following neonatal castration in male animals or following neonatal administration of testosterone to female animals.