ALTERED OVARIAN FOLLICLE FUNCTION IN ACTH-TREATED GILTS

To assess the possible influence of increased endogenous glucocorticoi d levels on ovarian function, gilts were treated with either adrenocor ticotrophic hormone (ACTH) or saline during the luteal phase of the oe strous cycle, from day 9 to day 14, and ovariectomised on day 14. Indi vidual follicles were dissected from each ovary and their follicular f luid (FF), granulosa and theca cells were recovered. Cell viability wa s determined by dye exclusion. Cortisol (C), oestradiol-17 beta (E(2)) , oestrone (E(1)), testosterone (T) and androstenedione (A) concentrat ions were measured in FF while cellular oestrogen and androgen product ion was assessed during a 3 h incubation period. The steroid hormone p rofile in FF was significantly altered in the treatment group. Follicl es collected from ACTH-treated gilts were characterised by elevated C (P<0.001), and E(1) (P < 0.05), but lower T and A (P < 0.01) levels; E (2) values also tended to be lower, but not significantly so. An incre ase (P < 0.01) in the proportion of follicles with lower granulosa cel l viability was observed on the ovaries of ACTH-treated gilts. There w ere no significant differences in E(2) or E(1) production, based on vi able cell numbers, during the 3 h incubation by either granulosa or th eca cells from control and ACTH-treated gilts. Theca cells collected f rom treated animals, however, produced significantly lower (P<0.01) A concentrations. These results indicate that ACTH treatment leading to elevated endogenous glucocorticoid levels during the luteal phase of t he oestrous cycle, prior to follicle recruitment, can reduce the propo rtion of viable granulosa cells per follicle. This change is associate d with altered steroid hormone concentrations in FF, but does not appe ar to involve suppression of aromatase activity.