Effects of ACTH on luteinizing hormone receptors in ovine follicular wall and corpus luteum

The effects of high systemic concentrations of ACTH during the days preceding ovulation on follicular wall and luteal tissue LH receptor concentration were studied at the expected time of ovulation and their evolution thereafter in 12 ewes. Controls (C; n = 3), received ten injections of sterile saline every 12 h, on days 11-16 of the estrous cycle, treated ewes (T-1, T-2, T-3; three animals each) received ten injections of ACTH (50 IU every 12 h). Ovariectomies were carried out in C and T-1 on day 16, in T-2 on day 18 and in T-3 on day 21. Relative to C, follicular concentration of LH receptors was approximately 50% in T-1 ewes (P < 0.025); but slightly higher (62%) in T-2, and dramatically increased (167%) in T-3. None of the animals displayed a preovulatory LH surge. ACTH treatment ment induced significant pathological effects on ovarian structures probably through treatment-induced increase in cortisol.