BACKGROUND: Orexin A (ORA) regulates food intake, energy metabolism, gastrointestinal and reproductive functions. AIM: The purpose of this study was to demonstrate whether the expression of 3β-hydroxysteroid dehydrogenase (3β-HSD) and testosterone was stimulated by ORA and mediated through mitogen-activated protein kinases (MAPK) in rat Leydig cells. METHODS: Primary Leydig cells were isolated from male rat testes, cultured, and treated with ORA under various conditions. RESULTS: Orexin receptor 1 (OX (1) R) mRNA, but not orexin receptor 2 mRNA, was detected in primary Leydig cells. ORA up-regulated the expression of OX( 1) R mRNA and protein in a dose-responsive manner and increased the phosphorylation of extracellular receptor kinase 1/2 (ERK1/2) and p38 MAPK levels, but did not affect the phosphorylation of the JNK MAPK. Phosphorylation of ERK1/2 and p38 MAPKs by ORA was blocked with U0126 and SB203580 inhibitors, respectively. An OX(1)R-specific inhibitor, SB334867, also blocked the phosphorylation of ERK1/2 and p38 by ORA. Inhibitor treatment also blocked 3β-HSD expression and testosterone production. CONCLUSIONS: These results demonstrate that ORA activation of OX(1)R up-regulates 3β-HSD expression and testosterone production via the ERK1/2 and p38 MAPKs signaling pathways in primary rat Leydig cells.
BACKGROUND:Orexin A (ORA) regulates food intake, energy metabolism, gastrointestinal and reproductive functions. AIM: The purpose of this study was to demonstrate whether the expression of 3β-hydroxysteroid dehydrogenase (3β-HSD) and testosterone was stimulated by ORA and mediated through mitogen-activated protein kinases (MAPK) in rat Leydig cells. METHODS: Primary Leydig cells were isolated from male rat testes, cultured, and treated with ORA under various conditions. RESULTS:Orexin receptor 1 (OX (1) R) mRNA, but not orexin receptor 2 mRNA, was detected in primary Leydig cells. ORA up-regulated the expression of OX( 1) R mRNA and protein in a dose-responsive manner and increased the phosphorylation of extracellular receptor kinase 1/2 (ERK1/2) and p38MAPK levels, but did not affect the phosphorylation of the JNK MAPK. Phosphorylation of ERK1/2 and p38 MAPKs by ORA was blocked with U0126 and SB203580 inhibitors, respectively. An OX(1)R-specific inhibitor, SB334867, also blocked the phosphorylation of ERK1/2 and p38 by ORA. Inhibitor treatment also blocked 3β-HSD expression and testosterone production. CONCLUSIONS: These results demonstrate that ORA activation of OX(1)R up-regulates 3β-HSD expression and testosterone production via the ERK1/2 and p38 MAPKs signaling pathways in primary rat Leydig cells.
Authors: H F Zhao; C Labrie; J Simard; Y de Launoit; C Trudel; C Martel; E Rhéaume; E Dupont; V Luu-The; G Pelletier Journal: J Biol Chem Date: 1991-01-05 Impact factor: 5.157
Authors: Gary Aston-Jones; Rachel J Smith; Gregory C Sartor; David E Moorman; Lema Massi; Pouya Tahsili-Fahadan; Kimberlei A Richardson Journal: Brain Res Date: 2009-10-06 Impact factor: 3.252