Expression of peroxisome proliferator-activated receptor α messenger ribonucleic acid and protein in human and rat testis

Peroxisome proliferator-activated receptor ct (PPAR alpha), a member of the steroid hormone receptor superfamily, has been linked to lipid homeostasis and tumorigenesis in tissues with high expression of receptor protein. On the other hand, the role of PPAR alpha in tissues with a lower expression is not well known. Here we demonstrate the localization of PPAR alpha messenger RNA (mRNA) and protein in developing and adult rat testis. Additionally, we demonstrate the expression of PPAR alpha protein in adult human testis. Our experiments with Northern analysis, in situ hybridization and immunocytochemistry reveal a complex distribution of PPAR alpha in tubular and interstitial cells of both adult and developing rat testis. The overall expression is rather low but may be modified by exogenous or endogenous stimuli. An up-regulation of PPAR alpha mRNA could be observed after stimulation with FSH. In the developing rat testis, a clear expression of PPAR alpha mRNA was present from the first days after birth. Additionally, PPAR alpha mRNA and protein increased toward adulthood. In adult human testis PPAR alpha immunoreactivity (IR) was present in interstitial Leydig cells and tubular cells. In the seminiferous epithelium of adult human testis the expression of PPAR alpha-IR could be seen in meiotic spermatocytes, spermatids and myoid peritubular cells. The findings of our study suggest that PPAR alpha may be involved in the regulation of growth and differentiation of tubular and interstitial cells in rat and human testis.