Catecholestrogens and release of anterior pituitary gland hormones. I. Luteinizing hormone.

We investigated the effects of peripheral administration of 17 beta-estradiol (E2), estrone (E1), and the catecholestrogens, 2-hydroxyestradiol (2-OHE2) and 2-hydroxyestrone (2-OHE1), on anterior pituitary gland LH release in the prepuberal rat. Steroids in oil were injected sc into 25-day-old female and 35- to 40-day-old male rats. The injection of E2, E1, or 2-OHE2 caused a surge in serum LH levels in female rats 48 h later, during the after hours. Only E1 induced a LH surge 24 h after injection. The positive effects of 2-OHE2 in the females were only observed if a massive dose was administered, the steroid was injected on 2 consecutive days, or E2 or progesterone was given to 2-OHE2-primed rats. The 2-OHE1 was totally ineffective in causing a serum LH surge under a variety of experimental protocols. In male rats, the injection of any one of the four steroids decreased serum LH levels. Even the injection of E2 or 2-OHE2 for 2 days or the injection of E2 in 2-OHE2-primed rats failed to elevate the serum LH concentration in male rats. The results suggest that 2-OHE2 and E1 could play a role in the preovulatory release of LH in the female; 2-OHE2 and 2-OHE1 could play a role in the negative feedback control of LH release in the male.