INFLUENCE OF LUTEINIZING-HORMONE-RELEASING HORMONE (LHRH) TREATMENT ON CELLULAR PROLIFERATION IN THE VAT ANTERIOR-PITUITARY

This study was designed to gain insight into the action of LHRH on the control of cellular proliferation in the anterior pituitary. The frac tion of cells labelled with bromodeoxyuridine (S-phase cells) was stud ied in cytospin preparations of anterior pituitary cells taken from co ntrol male and female rats and from rats treated with daily doses of 2 mu g/100 g body weight of LHRH (7 days), with doses of 40 mu g of LHR H given on alternate days for 14 days (7 doses) or, finally, treated w ith daily doses of 50 ng of busereline acetate (14 days). Treatment wi th LHRH for 14 days resulted in a significant increase in the fraction of S-phase cells. However, neither the blockade of gonadotrophin secr etion with busereline acetate nor its stimulation with LHRH for seven days resulted in a significant change in the proliferative activity of anterior pituitary cells. This action was independent of sex. No sign ificant changes were seen in the proportions of pituitary gonadotrops of the different study groups. Regardless of the treatment-group very few cells doubly-immunostained for BrdU and LH were found. It is concl uded that LHRH may stimulate cellular proliferation in the anterior pi tuitary, but further studies are needed to define which cells are invo lved in this action.