Expression of leptin and leptin receptor in the testis of fertile and infertile patients

The aim of our study was to investigate the relationships between the expression of leptin, leptin receptor in the testis and spermatogenesis, and testosterone (T) concentration in infertile men. Testicular tissue samples were collected from the testes of five fertile volunteers, eight patients with obstructive azoospermia (OA), six patients with Sertoli cell-only syndrome (SCO) and 32 oligospermic patients with varicocele testis. In testicular tissue, leptin and leptin receptor were identified by staining with polyclonal antibodies. Serum follicle stimulating hormone, lutenising hormone (LH), and T were determined by chemiluminescence assays. Leptin was expressed on germ cells, mainly on spermatocytes. The ratio of immunostained germ cells to total germ cells was inversely correlated with the concentration of T (r = -0.32, P = 0.01), sperm concentration (r = -0.51, P = 0.002) and Johnsen's score (r = -0.44,P = 0.005). In contrast, leptin receptor immunostained cells were found in the interstitium, primarily in Leydig cells. Leptin receptor expression on Leydig cells was inversely correlated with serum T concentration (r = -0.50, P < 0.001). The dysfunction of spermatogenesis is associated with an increase in leptin and leptin receptor expression in the testis.