Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, Tokyo, Japan.
Gen Comp Endocrinol. 2011 Jul 1;172(3):475-86. doi: 10.1016/j.ygcen.2011.04.011. Epub 2011 Apr 20.
In vertebrates, gonadal production of steroid hormones is regulated by follicle-stimulating hormone (FSH) and luteinizing hormone (LH) via their receptors designated FSHR and LHR, respectively. We have shown recently that steroid hormones are synthesized in the differentiating gonad of tadpoles during sex determination in the frog Rana rugosa. To elucidate the role of gonadotropins (GTHs) and their receptors in the production of gonadal steroid hormones during sex determination, we isolated the full-length FSHβ, LHβ, FSHR and LHR cDNAs from R. rugosa and determined gonadal expression of FSHR (FSH receptor) and LHR (LH receptor) as well as brain expression of FSHβ and LHβ during sex determination in this species. The molecular structures of these four glycoproteins are conserved among different classes of vertebrates. FSHβ expression was observed at similar levels in the whole brain (including the pituitary) of tadpoles, but it showed no sexual dimorphism during gonadal sex determination. By contrast, LHβ mRNA was undetectable in the whole brain of tadpoles. FSHβ-immunopositive cells were observed in the pituitary of female tadpoles with a differentiating gonad. Furthermore, FSHR expression was significantly higher in the gonad of female tadpoles during sex determination than in that of males, whereas LHR was expressed at similar levels in males and females. The results collectively suggest that FSHR, probably in conjunction with FSH, is involved in the steroid-hormone production during female-sex determination in R. rugosa.
在脊椎动物中，性腺类固醇激素的产生受卵泡刺激素（FSH）和黄体生成素（LH）通过其各自的受体 FSHR 和 LHR 调节。我们最近表明，在青蛙 Rana rugosa 的性别决定过程中，类固醇激素是在分化性腺中合成的。为了阐明促性腺激素（GTHs）及其受体在性别决定过程中产生性腺类固醇激素的作用，我们从 R. rugosa 中分离出全长 FSHβ、LHβ、FSHR 和 LHR cDNA，并确定了 FSHR（FSH 受体）和 LHR（LH 受体）在该物种性别决定过程中的性腺表达以及 FSHβ和 LHβ在脑中的表达。这四种糖蛋白的分子结构在不同类别的脊椎动物中是保守的。FSHβ 的表达在幼蛙的整个大脑（包括垂体）中水平相似，但在性腺性别决定过程中没有性别二态性。相比之下，LHβ mRNA 在幼蛙的整个大脑中无法检测到。在具有分化性腺的雌性幼蛙的垂体中观察到 FSHβ-免疫阳性细胞。此外，在性别决定过程中，雌性幼蛙的 FSHR 表达明显高于雄性，而 LHR 在雄性和雌性中的表达水平相似。这些结果表明，FSHR 可能与 FSH 一起参与了 R. rugosa 雌性性别决定过程中的类固醇激素产生。
