Effects of gonadotropin-releasing hormone agonist on human chorionic gonadotropin activity in granulosa cells of immature female rats

Abstract

Although the expression of gonadotropin-releasing hormone (GnRH) in the ovaries is well established, its physiological role remains unknown. The aim of this study was to determine whether ovarian GnRH mediates the actions of human chorionic gonadotropin (hCG) in the granulosa cells of immature female rats. Follicular growth was induced by administration of pregnant mare serum gonadotropin (PMSG, 15 IU/0.15 ml) on day 25 after birth, and hCG (20 IU/0.2 ml) was administered on day 27 revealing the increase of plasma progesterone level. Primary cultures of granulosa cells were established from large follicles 2 days after PMSG treatment. Progesterone synthesis was augmented by hCG in a dose-dependent manner. Annexin A5 (ANXA5), a biomarker of GnRH, was expressed in the granulosa-luteal cells after hCG treatment, as shown by immunohistochemistry, suggesting that hCG treatment induced GnRH action. The GnRH mRNA level was increased by hCG, and treatment with GnRH agonist (GnRHa) increased ANXA5 mRNA levels in the primary cultures of granulosa cells. Concomitant incubation of GnRH (10–7 M) or GnRHa (fertirelin acetate, 10–8 M) with hCG suppressed progesterone synthesis during a 3 h incubation period. The mRNA expression of luteinizing hormone receptor (LHR) and follicle-stimulating hormone receptor (FSHR) was synergistically stimulated and suppressed by hCG and GnRHa, respectively. GnRHa stimulated p21 expression, and GnRHa and hCG synergistically reduced the mRNA expression levels of p27 and FOXO1. These data suggest that GnRH induced by LH may have a role for the LH-mediated luteinization of granulosa cells. In addition, ANXA5 may be involved in GnRH action. GnRH-ANXA5 would be an important mechanism in cell differentiation.

Resveratrol Protects Rat Ovarian Luteinized Granulosa Cells from H2O2-Induced Dysfunction by Activating Autophagy

“…In this period, luteinized granulosa cells secrete progesterone and estradiol, becoming an important model in vitro to study the functions of the corpus luteum [ 25 ]. Twenty-one-day-old female presexual SD rats were treated with a combined hormone treatment of PMSG and hCG to induce ovarian luteinization, and the luteinized granulosa cells were successfully isolated and cultured in vitro according to the methods in some previous studies [ 26 , 27 ]. Although some red blood cells may mix with the luteinized granulosa cells, since the red blood cells cultured in suspension can be effectively removed by refreshing medium, it will not affect the subsequent experiments.…”

Gonadotropin-releasing hormone stimulation of annexin A5 expression in the thymus of male rats

“…GnRH is expressed in the hypothalamus and various other tissues [ 6 , 7 , 14 , 15 , 21 , 24 , 25 ]. Although the function of GnRH in these tissues is of interest, it is not well understood.…”

“…GnRH is transported to the anterior pituitary gland by the pituitary portal vessel and affects gonadotropin secretion by gonadotropes. Although accumulating evidence on GnRH suggests the significance of GnRH in reproduction, the non-reproductive functions of GnRH expressed in various peripheral tissues are not known [ 6 , 7 , 14 , 15 , 21 , 24 , 25 ].…”