Richard N, Galmiche G, Corvaisier S, Caraty A, Kottler M-L
Département Génétique et Reproduction, Unité de Formation et de Recherche de médecine, Centre Hospitalier Universitaire, Caen, France.
J Neuroendocrinol. 2008 Mar;20(3):381-93. doi: 10.1111/j.1365-2826.2008.01653.x. Epub 2008 Jan 17.
Kisspeptin, the product derived from KiSS-1, and its cognate receptor, GPR54, both exert a role in the neuroendocrine control of reproduction by regulating gonadotrophin-releasing hormone (GnRH) secretion. In the present study, we demonstrate, using dual immunofluorescence with specific antibodies, that the KiSS-1 and GPR54 genes are both expressed in rat gonadotrophs. All luteinising hormone beta-immunoreactive (LH beta-ir) cells were stained by the KiSS-1 antibody but some kisspeptin-ir cells were not LH beta positive; thus, we cannot exclude the possibility that kisspeptins are expressed in other pituitary cells. All GPR54-ir are co-localised with LH beta cells, but only a subset of LH beta cells are stained with the GPR54 antibody. Using the real-time reverse transcription-polymerase chain reaction (RT-PCR), we found that the expression of KiSS-1 and GPR54 is differentially regulated by steroids. In the female, KiSS-1 mRNA levels dramatically decreased following ovariectomy (OVX), and this decrease was prevented by administration of 17beta-oestradiol (E(2)), but not by administration of GnRH antagonist or agonist. Administration of E(2) in OVX rats receiving either GnRH antagonist or agonist clearly shows that E(2) acts directly on the pituitary to positively control KiSS-1 expression. In OVX rats, administration of the selective oestrogen receptor (ER)alpha ligand propylpyrazoletriol, but not the selective ER beta ligand diarylpropionitrile, mimics this effect. By contrast, our study shows that GPR54 expression is positively regulated by GnRH and negatively controlled by chronic exposure to E(2). In summary, our data document for the first time that, in the female rat pituitary, KiSS-1 expression is up-regulated by oestradiol, similarly to that seen in the anteroventral periventricular nucleus of the hypothalamus. Conversely, GPR54 is up-regulated by GnRH, which exclusively targets gonadotrophs.
亲吻素（Kisspeptin）是由KiSS-1基因产生的产物，其同源受体GPR54通过调节促性腺激素释放激素（GnRH）的分泌，在生殖的神经内分泌控制中发挥作用。在本研究中，我们使用特异性抗体进行双重免疫荧光实验，证明KiSS-1和GPR54基因均在大鼠促性腺细胞中表达。所有促黄体生成素β免疫反应性（LHβ-ir）细胞均被亲吻素抗体染色，但部分亲吻素免疫反应性（kisspeptin-ir）细胞并非LHβ阳性；因此，我们不能排除亲吻素在其他垂体细胞中表达的可能性。所有GPR54免疫反应性细胞均与LHβ细胞共定位，但只有一部分LHβ细胞被GPR54抗体染色。使用实时逆转录-聚合酶链反应（RT-PCR），我们发现KiSS-1和GPR54的表达受类固醇的差异调节。在雌性大鼠中，卵巢切除（OVX）后KiSS-1 mRNA水平显著下降，而给予17β-雌二醇（E₂）可防止这种下降，但给予GnRH拮抗剂或激动剂则无效。在接受GnRH拮抗剂或激动剂的OVX大鼠中给予E₂，清楚地表明E₂直接作用于垂体，对KiSS-1表达起正向调控作用。在OVX大鼠中，给予选择性雌激素受体（ER）α配体丙基吡唑三醇可模拟这种效应，而给予选择性ERβ配体二芳基丙腈则无此作用。相比之下，我们的研究表明，GPR54表达受GnRH正向调节，并受长期暴露于E₂的负向控制。总之，我们的数据首次证明，在雌性大鼠垂体中，KiSS-1的表达与在下丘脑室旁核前部所见情况类似，受雌二醇上调。相反，GPR54受GnRH上调，而GnRH仅作用于促性腺细胞。
