PAPP-A degrades IGFBPs in the ovary, and increases availability of IGFs. The objective of this study was to determine the effect of IGF-s, insulin, LH, FSH, estradiol, leptin or cortisol on ovarian PAPP-A mRNA in small- (SM) and large- (LG) follicle granulosa (GC) and LG theca (TC) cells. More PAPP-A mRNA was produced by GC than TC, but none of the treatments affected (P>0.10) PAPP-A mRNA in SM-GC and LG-GC. In LG-TC, insulin with or without LH decreased (P<0.05) PAPP-A mRNA; estradiol alone decreased PAPP-A mRNA and amplified the insulin-induced inhibition of PAPP-A mRNA expression. We conclude that PAPP-A gene expression is differentially regulated in granulosa and theca cells. Estradiol and insulin may act as negative feedback regulators to prevent excessive IGF-I - induced androgen production, and prevent excessive estradiol production by GC via decreased thecal PAPP-A production, maintaining desirable levels of IGFBP-4/-5 and subsequently free IGF-I /-II within the follicle.Department of Animal Scienc
