Potential roles of matrix metalloproteinases and characteristics of ovarian development in neonatal guinea pigs

• Injection of eCG sensitized the neonatal ovary and elevated serum concentrations of estradiol and progesterone, but not enough to stimulate ovarian follicular development in the ovaries.
• MMP-2 and MMP-9 were both immunolocalized to the surface of granulosa cells of primary and secondary follicles.
• We hypothesize that MMP-2, -9 and StAR are both involved in follicular atresia through their participation in cell proliferation and tissue remodeling.

The present study was conducted to investigate expression of matrix metalloproteinases (MMPs) and early ovarian development in neonatal guinea pigs. Thirty neonatal guinea pigs at 3 or 8 days of age were administrated 5 IU equine chorionic gonadotropin (eCG) or saline, and the ovaries were collected after 2 days of eCG. Serum concentrations of estradiol and progesterone were determined, and ovarian localization of StAR, MMP-2 and MMP-9 were analyzed by immunohistochemical staining. Results indicate that injection of eCG sensitized the neonatal ovary and elevated serum concentrations of estradiol and progesterone, but not enough to stimulate ovarian follicular development in the ovaries. MMP-2 and MMP-9 were both immunolocalized to the surface of granulosa cells of primary and secondary follicles, and high MMP-2 expression was accompanied by low StAR expression in eCG-treated ovaries. Collectively, we hypothesize that MMP-2, -9 and StAR are both involved in follicular atresia through their participation in cell proliferation and tissue remodeling.

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