title: Gonadotropin-releasing hormone positively regulates steroidogenesis via extracellular signal-regulated kinase in rat Leydig cells.
abstract: 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 ERK1/2 by GnRHa reached peak at 5 min and it returned to the basal level within 60 min. PD-98059 completely blocked the activation of ERK1/2, 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-HSD gene expression and enzyme production, which may ultimately modulate steroidogenesis in rat Leydig cells.
authors: Department of Reproduction and Genetics, Nanjing Jingling Hospital, Nanjing 210002, China.
authors: Bing
authors: B
authors: Yao
authors: Hai-Yan
authors: HY
authors: Liu
authors: Yu-Chun
authors: YC
authors: Gu
authors: Shan-Shan
authors: SS
authors: Shi
authors: Xiao-Qian
authors: XQ
authors: Tao
authors: Xiao-Jun
authors: XJ
authors: Li
authors: Yi-Feng
authors: YF
authors: Ge
authors: Ying-Xia
authors: YX
authors: Cui
authors: Guo-Bin
authors: GB
authors: Yang
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000096:biosynthesis; D000818:Animals; D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects / Q000378:metabolism*; D005419:Flavonoids / Q000494:pharmacology; D007987:Gonadotropin-Releasing Hormone / Q000819:agonists / Q000494:pharmacology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D013739:Testosterone / Q000096:biosynthesis; D015854:Up-Regulation
chemical_list: D005419:Flavonoids; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D015096:3-Hydroxysteroid Dehydrogenases; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one