All-trans-retinoic acid induces apoptosis in Leydig cells via activation of the mitochondrial death pathway and antioxidant enzyme regulation

In addition to playing a fundamental role indiverse processes, such as vision, growth and differentiation,vitamin A and its main biologically active derivative,retinoic acid (RA), are clearly involved in the regulation oftesticular functions. The present study was undertaken toexamine the direct effect of RA treatment on Leydig (TM-3)cells. TM-3 cells were cultured and treated with varyingconcentrations of RA for 24h. High doses of RA (1–20μM)induced a decrease in cell vitality and an increase in lipidperoxidation. RA treatment also induced a correspondingincrease in apoptosis in the same cells in a dose-dependentmanner. Apoptosis proceeded via the mitochondrial dependentpathway, as demonstrated by the release of cytochromec, caspase-3 enzymatic activation and DNA fragmentation.Conversely, at physiological doses (0.1–500nM) RA did notincrease lipid peroxidation or cell death and resulted in anincrease of antioxidant enzyme activity.