Regulation of Angiogenesis by Insulin-Like Growth Factor in the Bovine Corpus Luteum: A Preliminary Study
In the ovary, growth of a new vascular network, or angiogenesis, is a hallmark of corpus luteum (CL) development. This process requires several angiogenic factors and matrix metalloproteinases (MMPs). Recently, we reported the expression of an angiogenic inducer, Cysteine rich 61-Connective tissue growth factor-Nephroblastoma overexpressed (CCN1), in the bovine CL. However, it is not known how CCN1 is regulated in the CL. Therefore, the goals of the present study were 1) to determine the regulation of CCN1 by insulin-like growth factor (IGF-1) during the early (Day 4), mid (Day 8), and late (Day 16) stages of CL development, and 2) to determine the effect of IGF-1 on MMP 2 and 9, both of which are involved in angiogenesis. Preliminary results showed that CCN1 was rapidly induced within 2 to 4 hours. As such, luteal cells were treated for 2 hours with IGF-1 (50 ng/mL and 100 ng/mL). Analysis via quantitative PCR (qPCR) suggests that treatment with IGF-1 may increase CCN1 expression in the mid and late stage CLs. Zymography results suggest that IGF-1 may increase MMP 2 expression in mid and late stage CL and MMP 9 expression in the early and mid-stage CL. These experiments will be repeated to confirm observations.