흰쥐에서 난소제거가 Follocle Stimulating Hormone(FSH)분비와 FSHβ Subunit mRNA에 미치는 영향

Abstract

Follicle stmulating hormone ( FSH ) consist of α and β subunits, which are encoded by se-parate genes. Pituitary release of FSH appears to be regulated by the hypothalamic GnRH and the gonadal steroid hormones. In addition , inhibin and follistatin produced by the gonad have been known to inhibit FSH secretion selectively. However , little is known about their regulation of the biosynthesis of FSH subunits at transcriptional and posttranscriptional levels. In the pre-sent study , we studied the time course of changes in α and FSHβ subunit mRNA concentrati-ons after castration and the effects of ovarian steroids of changes in α and FSHβ subunit mRNA concentrations after castration and the effects of ovarian steroids on α and FSHβ subunit mRNA in ovariectomized rats in order to determine Whether FSH subunit synthesis is modulated at the pretranslational levels, and whether synthesis and secretion are differently regulated. Results are as follows： 1. The time course of the rise in the steady state α subunit and FSHβ subunit mRNA levels were observed after ovariectomy, which paralleled the increases in serum and pituitary FSH concentrations. The time course experiments revealed differences in the patterns of α and FSHβ subunit mRNA responses , the rise in FSHβ subunit mRNA levels being more pro- minent than the rise in α subunit mRNA. 2. FSHβ mRNA levels were negatively regulated by the single injection of progesterone but not by estradiol , suggesting that FSHβ subunit mRNA seemed to be more sensitive to ne-gative feedback by progesterone than estradiol. Similar results were obtained by the continuous treatment of ovarian steroids for 1∼4 days , but inhibition was more prominent with continuous treatment. It is , therefore , concluded that estradiol and progesterone inhibit the synthesis of FSH at the pretranslational level by modulating the steady state levels of α and FSHβ subunit mRNA , progesterone effect being more promiment than that of estradiol and α and FSHβ subunit are regulated in a different manner.