O'Shaughnessy P J, Gray S A
Department of Veterinary Physiology, University of Glasgow Veterinary School, United Kingdom.
Endocrinology. 1995 May;136(5):2060-5. doi: 10.1210/endo.136.5.7720655.
The inhibins and activins are dimeric growth factors with important regulatory functions during development. In this study, changes in inhibin subunit messenger RNA (mRNA) levels were measured in the ovary during early postnatal development in the normal mouse and the hypogonadal (hpg) mouse, which lacks circulating gonadotropins. Levels of inhibin alpha-, beta A-, and beta B-subunit mRNAs were measured relative to beta-actin using a semiquantitative reverse transcription-polymerase chain reaction technique. Transcripts encoding all three subunits were present at birth; the alpha-subunit was the most abundant, followed by beta A-subunit (6% of alpha) and beta B-subunit (0.4% of alpha). After birth, levels of all three subunit transcripts increased between 6- and 10-fold. Changes in inhibin beta A- and beta B-subunit levels were most marked around 7 days, the period of secondary follicle development, whereas alpha-subunit transcript levels increased constantly after day 1 to reach a peak at 10 days, when mature secondary follicles are present. In hpg mice, levels of ovarian inhibin alpha-subunit mRNA levels were normal at all ages up to 15 days. In contrast, inhibin beta A-subunit mRNA levels were normal at birth in hpg mice, but did not increase after that up to day 15. Levels of beta B-subunit mRNA were significantly lower than normal on day 1 in hpg mice and also failed to show a significant increase up to 15 days. These results show that inhibin subunit mRNA levels are differentially regulated during ovarian development in the mouse. Normal expression of beta-subunits is completely gonadotropin dependent around the period of late primary to secondary follicle development. The inhibin alpha-subunit, in contrast, is expressed at a high level during development independent of gonadotropin stimulation.
抑制素和激活素是二聚体生长因子，在发育过程中具有重要的调节功能。在本研究中，我们检测了正常小鼠和缺乏循环促性腺激素的性腺功能减退（hpg）小鼠出生后早期发育过程中卵巢中抑制素亚基信使核糖核酸（mRNA）水平的变化。使用半定量逆转录-聚合酶链反应技术，相对于β-肌动蛋白测量抑制素α-、βA-和βB-亚基mRNA的水平。出生时即存在编码所有三个亚基的转录本；α-亚基最为丰富，其次是βA-亚基（α的6%）和βB-亚基（α的0.4%）。出生后，所有三个亚基转录本的水平增加了6至10倍。抑制素βA-和βB-亚基水平的变化在约7天时最为明显，这是次级卵泡发育的时期，而α-亚基转录本水平在第1天后持续增加，在第10天达到峰值，此时存在成熟的次级卵泡。在hpg小鼠中，直至15日龄时卵巢抑制素α-亚基mRNA水平在所有年龄段均正常。相比之下，hpg小鼠出生时抑制素βA-亚基mRNA水平正常，但之后直至15日龄均未增加。hpg小鼠在第1天时βB-亚基mRNA水平显著低于正常水平，直至15日龄也未显示出显著增加。这些结果表明，在小鼠卵巢发育过程中抑制素亚基mRNA水平受到不同的调节。在初级卵泡晚期至次级卵泡发育期间，β-亚基的正常表达完全依赖于促性腺激素。相比之下，抑制素α-亚基在发育过程中高水平表达，不依赖于促性腺激素刺激。
