Effect of visfatin on testicular steroidogenesis in purified Leydig cells.

BACKGROUND Lower testosterone levels have been reported in men suffering from diabetes mellitus. Men with insulin resistance states such as obesity and type 2 diabetes mellitus have significantly lower testosterone levels than age-matched normal weight and non-diabetic controls. Adipose tissue secretes variety of adipokinesincluding adiponectin, resistin, visfatin, TNF-alpha. The study was designed to study the effect of visfatin on testicular steroidogenesis in purified Leydig cell in vitro. METHODS Leydig cells of Sprague Dawley rats were isolated and purified by Percoll. Cells were incubated for 3 hours with/without visfatin in the presence/absence of LH and intracellular signalling blockers including PKC blocker, PKA blocker and Raf1/Ras blocker. Cell culture extracts were stored at -80 before analysis for levels of testosterone hormone by ELISA. RESULTS Visfatin increased testosterone production (p < 0.001) from cultured Leydig cells. Raf1/Ras blocker decreased visfatin induced steroidogenesis (p < 0.001). CONCLUSION Visfatin increased testicular steroidogenesis from Leydig cells in vitro models and operates through variety of enzymes, but especially through Ras/Raf1 kinase enzymes.