| Abstract: | Anterior pituitary gland and hypothalamic 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity was measured in the immature castrated estradiol primed rat to determine if differences in enzyme activity could explain the progesterone induced reduction of bound estradiol nuclear receptors of the anterior pituitary gland but not the hypothalamus. Higher levels of 17 beta-HSD activity were found in the anterior pituitary gland as compared to the hypothalamus. The enzyme activity in the anterior pituitary gland was stimulated by progesterone administered either in combination with estradiol for 4 days or as a single injection following 4 days of estradiol priming. No progesterone effects were found on hypothalamic 17 beta-HSD. Under the experimental conditions used, progesterone administration did not alter uterine 17 beta-HSD. An increase in anterior pituitary gland and uterine 17 beta-HSD was also induced by estrogen administration. |
