Influence of Follicular Maturation on Inhibition of Luteinizing Hormone-, Cyclic 3′, 5′-Adenosine Monophosphate-, and Forskolin-Stimulated Progesterone Production in Chicken Ovarian Granulosa Cells Exposed to Bursal Anti-Steroidogenic Peptide1

Abstract

Previously, we demonstrated that a peptide from chicken bursa of Fabricius, bursal anti-steroidogenic peptide (BASP), inhibited LH-stimulated progesterone biosynthesis by granulosa cells from the two largest preovulatory follicles of the chicken ovary. In the present study, we investigated the influence of follicular maturation on the ability of BASP to inhibit granulosa cell steroidogenesis. Granulosa cells from the largest (F1), third largest (F3), and fifth largest (F5), preovulatory follicles of the laying hen were exposed to BASP in the presence or absence of ovine LH, forskolin, or dibutyryl-cAMP (db-cAMP). BASP (0.125 or 0.25 bursal equivalents [BEQ]) suppressed basal progesterone production in F5, but not in F1 or F3, granulosa cells. BASP suppressed LH-stimulated progesterone production in F1, F3, and F5 granulosa cells in a concentration-dependent manner; however, the lowest level (0.06 BEQ) did not suppress progesterone production in F5 granulosa cells. All levels of BASP suppressed forskolin-stimulated progesterone production in F1 granulosa cells, but only the highest level (0.25 BEQ) inhibited forskolin-stimulated steroidogenesis in F3 and F5 granulosa cells. Similar results were obtained with db-cAMP-stimulated granulosa cells. The inhibitory effects of BASP on F1, F3, and F5 granulosa cells were directly compared on a percentage basis. In the presence of each secret-agogue, the lowest level (0.06 BEQ) of BASP effectively suppressed progesterone synthesis in F1 and F3 but not F5 granulosa cells. At higher levels, there was no consistent difference in the ability of BASP to suppress stimulated progesterone production in granulosa cells at different stages of maturation.(ABSTRACT TRUNCATED AT 250 WORDS)