GnRH通过ERK途径来调控大鼠睾丸间质细胞类固醇激素的合成

GnRH是由下丘脑神经元分泌,且在脊椎动物生殖功能中非常的必要。GnRH还被发现存在于脑以外的组织中,在睾丸间质细胞的炎阎醇激素合成过程中发挥了重要的作用。然而,信号通路对其的调节作用仍然不清楚。本研究我们主要检测MAPK信号通路是否参与GnRH激动剂（GnRHa）诱导的雄激素的合成。我们建立了间质细胞的原代培养的方法。不同浓度GnRHa刺激间质细胞不同时间后3D—HSD和苇酮的量通过RT-PCR,Westernblot和RIA测定。在MAPK抑制剂PD-98059存在或不存在的情况下,我们也通过Westernblot的方法检测GnRHa对ERK1／2,JNK和p38的作用。结果显示GnRHa诱导睾酮的合成并且上调3β-HSDmRNA水平以及蛋A水平,同时也激活了ERK1／2水平,但是对JNK和p38的活化没有作用。虽然GnRHa最佳的浓度是100nmnol L-1,最佳时间是24h,但是GnRHa~]激细胞5min后ERK1／2活化作用达到最高水平,60min之内恢复到本地水平。而PD-98059则能完全阻滞ERKl／2活化,3β-HSD的上调以及睾酮合成。我们的数据显示GnRH通过ERK途径来调控大鼠睾丸间质细胞雄性激素的合成。GnRH对ERK1／2的活化诱导了3β—HSD基因和蛋白的表达,最终调节大鼠间质细胞类固醇激素的合成。

Gonadotropin-releasing hormone positively regulates steroidogenesis via extracellular signal-regulated kinase in rat Leydig cells

Gonadotropin-releasing hormone （GnRH） is secreted from neurons within the hypothalamus and is necessary for reproductive function in all vertebrates. GnRH is also found in organs outside of the brain and plays an important role in Leydig cell steroidogenesis in the testis. However, the signalling pathways mediating this function remain largely unknown. In this study, we investigated whether components of the mitogen-activated protein kinase （MAPK） pathways are involved in GnRH agonist （GnRHa）-induced testis steroidogenesis in rat Leydig cells. Primary cultures of rat Leydig cells were established. The expression of 3β-hydroxysteroid dehydrogenase （3β-HSD） and the production of testosterone in response to GnRHa were examined at different doses and for different durations by RT-PCR, Western blot analysis and radioimmunoassay （RIA）. The effects of GnRHa on ERK1/2, JNK and p38 kinase activation were also investigated in the presence or absence of the MAPK inhibitor PD-98059 by Western blot analysis. GnRHa induced testosterone production and upregulated 3β-HSD expression at both the mRNA and protein levels; it also activated ERK1/2, but not JNK and p38 kinase. Although the maximum effects of GnRHa were observed at a concentration of 100 nmnol L-1 after 24 h, activation of ERKI/2 by GnRHa reached peak at 5 min and it returned to the basal level within 60 min. PD-98059 completely blocked the activation of ERKI/2, the upregulation of 3β-HSD and testosterone production. Our data show that GnRH positively regulates steroidogenesis via ERK signalling in rat Leydig cells. ERK1/2 activation by GnRH may be responsible for the induction of 3β-HSDgene expression and enzyme production, which may ultimately modulate steroidogenesis in rat Leydig cells.