Abstract
We have recently reported that, in the testis, porcine immature Sertoli cells cultured in a serum-free defined medium, release Somatomedin C / immunoreactive IGF 1 (irSmC) stimulated by FGF but not by GH (Ann. Endocrinol. 1985, 46, 287). In the present report, we show that SmC/IGF1 is a potent regulator of Leydig cell differentiation. The effect of SmC/IGF 1 on Leydig cell activity was studied by incubating porcine immature Leydig cells with a biosynthetic SmC. SmC/IGF1 exerted a dose and time dependent stimulating effect on Leydig cell function, with the maximal response obtained at 50 ng/ml after 48hrs treament. SmC/IGF1 increased both LH/hCG binding (x4-5), basal(x4) and hCG-stimulated (x15.5) testosterone secretion. The slight effects of SmC/IGF1 (100ng/ml for 48hrs) on Leydig cell number (x1.3) and DNA synthesis (x1.5) in the comparison with the high steroidogenic effect support the concept that SmC/IGF1 acts as a cytodifferenciative factor rather than a growth factor. The steroidogenic action of SmC/IGF1 was not suppressed by cytosine arabinoside C, a DNA synthesis inhibitor, supporting the concept of the cytodifferenciative role of this peptlde. In conclusion, the production by Sertoli cells of irSmC/IGF1 associated with the stimulating effect of SmC/IGF1 on steroidogenesis, suggest that this peptide could be an intratesticular regulator of Leydig ceil differentiation.
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Benahmed, M., Morera, A., Chauvin, M. et al. SOMATOMEDIN C/INSULIN LIKE GROWTH FACTOR 1: AN INTRATESTICULAR DIFFERENTIATING FACTOR OF LEYDIG CELLS?. Pediatr Res 20, 1192 (1986). https://doi.org/10.1203/00006450-198611000-00110
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DOI: https://doi.org/10.1203/00006450-198611000-00110