Zhang Lihong, Kessler Ann E, Tsai Pei-San
School of Life Sciences, Zhongshan (Sun Yat-Sen) University, Guangzhou 510275, PR China.
Gen Comp Endocrinol. 2007 Jan 1;150(1):66-74. doi: 10.1016/j.ygcen.2006.07.006. Epub 2006 Aug 22.
In ranid frogs, the secretion of gonadotropins (GtHs), luteinizing hormone (LH), and follicle-stimulating hormone (FSH), is potently regulated by gonadal steroids. To better understand the gonadal regulation of GtHs at the molecular level, we elucidated the full-length cDNA sequences of LH and FSH beta subunits from the leopard frog, Rana pipiens. The cDNAs for LHbeta and FSHbeta were 1084 and 667 bp in size excluding the poly (A) tail, and encoded proteins of 138 and 127 amino acids, respectively. Using reverse-transcription polymerase chain reaction (RT-PCR), the messages for LHbeta and FSHbeta were found in the pituitary, but not in the brain, heart, kidney, or the liver. Semi-quantitative RT-PCR revealed a significant elevation of FSHbeta, but not LHbeta, in mature male R. pipiens 21 days after gonadectomy (GDX). 17beta-estradiol implant for 21 days in GDX male frogs significantly suppressed the levels of both LHbeta and FSHbeta transcripts, whereas 5alpha-dihydrotestosterone implant suppressed only the latter. Together, these results laid the groundwork for investigating gonadal regulation of GtHbeta subunits in a ranid frog. Importantly, these data also revealed differential feedback effects of an androgen and an estrogen upon GtHbeta expression.
在蛙科蛙类中，促性腺激素（GtHs）、促黄体生成素（LH）和促卵泡激素（FSH）的分泌受到性腺类固醇的有效调节。为了在分子水平上更好地理解性腺对促性腺激素的调节作用，我们阐明了豹蛙（北美豹蛙）促黄体生成素和促卵泡激素β亚基的全长cDNA序列。促黄体生成素β亚基（LHβ）和促卵泡激素β亚基（FSHβ）的cDNA大小分别为1084和667 bp（不包括poly(A)尾），分别编码138和127个氨基酸的蛋白质。利用逆转录聚合酶链反应（RT-PCR）发现，LHβ和FSHβ的信使核糖核酸（mRNA）存在于垂体中，但在脑、心脏、肾脏或肝脏中未发现。半定量RT-PCR显示，在性腺切除术后21天的成熟雄性北美豹蛙中，FSHβ显著升高，但LHβ未升高。在性腺切除的雄性蛙中植入17β-雌二醇21天可显著抑制LHβ和FSHβ转录本的水平，而植入5α-双氢睾酮仅抑制后者。这些结果共同为研究蛙科蛙类中促性腺激素β亚基的性腺调节奠定了基础。重要的是，这些数据还揭示了雄激素和雌激素对促性腺激素β亚基表达的不同反馈作用。
