Influence of Follicular Maturation on Progesterone Release in Chicken Granulosa Cells in Response to Turkey and Ovine Gonadotropins

Abstract

Progesterone release in response to ovine and turkey LH and FSH was studied in chicken granulosa cells isolated from ovarian follicles of different maturational stages. The turkey LH (tLH) preparation was about 10 times more potent than ovine LH (oLH) whereas oFSH had a greater steroidogenic potency than tFSH when incubated with granulosa cells from the largest follicle (PRF-1). Turkey LH and oLH were less effective in stimulating progesterone production in cells from less mature follicles. Conversely, the FSH preparations showed a greater effect on the less mature follicles. LH-stimulated progesterone production by cells isolated from the postovulatory follicle (POF-1) 2–4 h after follicular rupture was greatly diminished and was similar to that of PRF-3 cells (68–70 h prior to ovulation). Treatment of tFSH and tLH with anti-tLH serum completely abolished the steroidogenic effect of tLH on all of the developing granulosa cells, and the effect of tFSH in PRF-1 cells was also eliminated. On the other hand, control tFSH (treated with normal rabbit serum) optimally stimulated PRF-1 cells, indicating that FSH-elicited progesterone secretion in granulosa cells from mature follicles was entirely due to LH-contamination. In cells from immature follicles (PRF-5), both untreated and antiserum-treated FSH promoted progesterone to a similar extent whereas tLH-induced responses were dramatically reduced. These studies demonstrate that in avian granulosa cells, as in mammalian ovarian cells, the maturational state of the follicle has a profound influence on gonadotropin-induced steroidogenesis.