METHALLIBURE, DELAYED PUBERTY AND THE PITUITARY-HYPOTHALAMIC COMPLEX OF FEMALE RATS

Methallibure prevents the onset ofpuberty and ovulation and inhibits pituitary gonadotrophic activity in 30-day-old rats (Walpole, 1968). The compound also reduces food intake (Benson & Zagni, 1965) and body weight in adult rats(Labhsetwar & Walpole, 1972). Restriction of food intake per se causes a deficiency in LH secretion in adult rats (Howland, 1971), but Labhsetwar & Walpole (1972) have shown that the reduction in pituitary and plasma LH produced by methallibure in adult spayed rats is not secondary to its effect on food intake. It is due, presumably, to a primary effect on the hypothalamo-hypophysial complex (Malven, 1971). In the present study, we explored the recurrence of delayed puberty in intact rats treated with methallibure (Ayerst). Twenty-eight-day-old female rats of Sprague-Dawley strain from the Charles River Company were housed under standard conditions of lighting (07.00 to 21.00 hours) and temperature (71 to 72\s=deg\F).One group, having free access to food, served as fully fed controls. The treatment group received methallibure(40 mg/kg/day in 0\m=.\2 ml of 0\m=.\5 % Tween 80) orally for 20 days beginning at 28 days of age. The food consumption of these rats was measured daily and the same amount offered on the following day to those in the pair-fed group. (On