Effects of the daily administration of gonadotrophin-releasing hormone on the anterior pituitary gland of rats with restricted feeding

Abstract

ABSTRACT To investigate the influence of weight reduction on pituitary function and its modulation by gonadotrophin-releasing hormone (GnRH), female rats were restricted to 10 g food/day for 60 days. GnRH (5 μg) or saline (0·2 ml) were administered daily between days 31 and 60 of the period of underfeeding. Underfeeding brought about a decrease in the pituitary gonadotrophin content, serum levels of gonadotrophins and oestradiol, and the number and size of both LH- and FSH-positive pituitary cells. The administration of GnRH to underfed rats produced an increase in the pituitary and serum gonadotrophin levels and the number and size of both LH- and FSH-positive pituitary cells. These observations suggest that underfeeding and/or weight loss diminish the number and activity of the pituitary gonadotrophs, and that daily administration of GnRH both increases the number of gonadotrophs and augments their activity. Journal of Endocrinology (1992) 134, 177–182