Postnatal ovarian development and its relationship with steroid hormone receptors in JiNing Grey goats

Abstract

In this work, we examined the ovarian development and its relationship with steroid hormone receptors levels and the precocious puberty in JiNing Gray goats by using optical microscopy, immunohistochemistry, quantitative real-time RT-PCR (qPCR) and Western blotting. We found that in the ovaries of neonatal kids, high level of receptors for estrogen (ERα and ERβ) and progesterone (PR) and their mRNA were observed along with growing follicles. From 0 to 30 days of age, the weight and volume of ovaries increased significantly and the boundary between the inner and outer cortex disappeared, while the expression of ERα, ERβ and PR and their mRNA decreased sharply. When 60 days old, the animals began to ovulate; the expression of ERα, ERβ and PR and their mRNA significantly increased, and the animals reached puberty. On day 90, the animals manifested sexual maturity with biggest mature follicles 6.18mm in diameter, the expression of ERβ and PR protein and their mRNA was maintained at a high level, with decreased expression of ERα and its mRNA. Before puberty, the expression of ovarian ERα (prepubertal dominant receptor) and it's mRNA was significantly higher than that of ERβ (dominant receptor after sexual maturity). The results showed that JiNing Grey goats' ovaries had fast development and early maturation, and ERα, ERβ and PR protein and mRNA expression in the ovary had distinct specificity for time and space, which may be closely related to the strain's progenitive characteristics.