Gene expression related to growth axis and gonadal axis in puberty rats

Abstract

To elucidate the effect and effective mechanism of gonadotropin-releasing hormone analog (GnRHa) on growth axis and gonadal axis in puberty rats.After injecting GnRHa on puberty rats, hypothalamus, pituitary, ovary and epiphyseal cartilage of legs were taken, and related gene expression was detected by fluorescence quantitative PCR (FQ-PCR).GnRHa could reduce the gene expression of gonadotropin-releasing hormone (GnRH) in hypothalamus and its receptor (GnRHR) in pituitary, increase the gene expression of growth hormone releasing inhibiting hormone (SRIH), and not affect the gene expression of growth hormone releasing hormone (GHRH) in hypothalamus. And GnRHa could reduce the gene expression of growth hormone (GH) in pituitary, estrogen receptor (ER) in ovary and insulin-like growth factors-I (IGF-1) in epiphyseal cartilage of legs.Besides restraining the gene expression of GnRHR in pituitary and leading to descent regulation of receptor, GnRHa can reduce the gene expression of GnRH in hypothalamus and down-regulate gonadal hormone level. At last, GnRHa can reduce the maturity degree and pace of the second sexual characteristics. By means of increasing the gene expression of SRIH in hypothalamus, GnRHa can reduce the gene expression of GH in pituitary and IGF-1 in epiphyseal cartilage of legs. It could be one of the mechanisms of GnRHa reducing epiphyseal maturity for the patients with idiopathic central precocious puberty.