Expression of the Leptin Receptor during Germ Cell Development in the Mouse Testis

Leptin, a recently identified hormonal product of the ob gene, is known to regulate appetite, body metabolism, and reproductive functions. We investigated the expression of the leptin receptor (Ob-R) in testes from different age groups. The messenger RNA for Ob-R was found in testes from all age groups using RT-PCR. Using immunohistochemistry, we observed age-and stage-dependent distribution of the Ob-R in mouse testis. In testis of 5-day-old mice, its expression was mainly in type A spermatogonia. In the 20-and 30-day-old testis, Ob-R expression was in the spermatocytes; in the adult testis, it was specific to spermatocytes in stages IX and X of the cycle of the seminiferous epithelium. Five main immunoreactive proteins were de-