The relationship between steroidogenesis and tissue remodeling enzymes in ovulation in cycling pony mares

摘要

Ovulation is a dynamic process which involves a poorly understood series of tissue remodeling events, likely involving matrix metalloproteinases (MMPs) and their inhibitors (TIMPs). There is evidence suggesting that one action of progesterone (P4) is to regulate the expression of MMPs, leading to ovulation and luteinization [1,2]. It has been shown in many species that gonadotropin stimulation by LH can increase MMP activity. LH specifically stimulates MMPs such as collagenase, gelatinase and proteoglycans, all of which are believed to play a critical role in the overall tissue remodeling associated with ovulation [3,4]. LH-like compounds such as hCG are commonly used throughout the horse industry to stimulate ovulation, yet very little is known about how use of gonadotropins affects follicular tissue remodeling to promote ovulation. Therefore, these studies were designed to evaluate the relationship of steroidogenesis and the tissue-remodeling enzymes and their role in the ovulatory process in response to gonadotropin stimulus. Specifically, we tested the hypotheses that: (1) gonadotropin administration to mares in estrus enhances MMPs, and affects steroidogenesis; (2) inhibition of MMPs leads to altered steroidogenesis and (3) inhibition of steroid action negatively affects MMPs.