| Ovarian follicular growth and dominance is controlled by a series of hormonal events including a decrease in intrafollicular IGF-binding proteins-2, -4 and -5 levels. Proteolytic enzymes such as pregnancy-associated plasma protein-A (PAPP-A) degrade IGFBPs and increase availability of IGF-I and -II during follicular development. The objective of this study was to determine the effect of IGF-I, IGF-II, insulin (INS), LH, FSH, estradiol (E), leptin or cortisol on ovarian PAPP-A mRNA levels. Granulosa (GC) from small (SM) (<5 mm) and large (LG) (>7.9 mm) follicles as well as theca cells (TC) from LG follicles were collected from bovine ovaries and cultured for 48 h in medium containing 10% FCS and then treated with various hormones in serum-free medium for an additional 12 or 24 h. LG-GC and LG-TC were cultured for either 12 or 24 h with 0 or 100 ng/mL of IGF-I or -II (exp 1 and 2). In all other experiments, SM-GC LG-GC and LG-TC were treated with various combinations of IGF-I, IGF-II, FSH, LH, E, INS, leptin and (or) cortisol for 24 h (exp 3 through 12). PAPP-A mRNA expression levels quantified using quantitative real-time RT-PCR. (Abstract shortened by UMI.)... |
