Abstract: BACKGROUND AND OBJECTIVE：To study the effects of insulin-like growth factor-I (IGF-I) and human chorionic gonadotropin (hCG) on expressions of glucose transporters (GLUTs) gene and testosterone production in adult rat Leydig cells and the relationship between steroidogenesis and glucose metabolism in adult rat Leydig cells. MATERIAL AND METHODS：The rat Leydig cells were isolated using modified Klinefelter’s method. The regulatory effects of IGF-Ⅰand hCG on GLUTs gene expression in primary cultured rat Leydig cells were investigated by RT-PCR. RESULTS：The rat Leydig cells with the purity of 98 ％ were isolated. hCG caused dose- and time-dependent increases of GLUT8 mRNA levels. IGF-I (100 ng/ml) could also increase GLUT8 mRNA expression significantly. IGF-I and hCG had synergistic effects on GLUT8 mRNA expression (P<0.001). This result was consistent to the result from the experiment in which IGF-I (100 ng/ml) and hCG (10 ng/ml) can increase testosterone level synergistically (P<0.001). However, in primary cultured rats Leydig cells, neither GLUT1 nor GLUT3 mRNA expression was affected by the treatment with hCG(10 ng/ml), IGF-I (100 ng/ml), or the combination of hCG (10 ng/ml) and IGF-I (100 ng/ml). CONCLUSION： In adult rat Leydig cells, regulatory effects of IGF-I and hCG on GLUT8 mRNA expression are specific. IGF-I and hCG can significantly increase GLUT8 mRNA expression level synergistically.

Key words: rat Leydig cell, insulin-like growth factor-I, human chorionic gonadotropin, glucose transporter, regulation