Association of cellular and molecular alterations in Leydig cells with apoptotic changes in germ cells from testes of Graomys griseoflavus × Graomys centralis male hybrids

Spermatogenesis is disrupted in Graomys griseoflavus × Graomys centralis male hybrids. This study was aimed to determine whether morphological alterations in Leydig cells from hybrids accompany the arrest of spermatogenesis and cell death of germ cells and whether apoptotic pathways are also involved in the response of these interstitial cells. We used three groups of 1-, 2- and 3-month-old male animals: (1) G. centralis, (2) G. griseoflavus and (3) hybrids obtained by crossing G. griseoflavus females with G. centralis males. Testicular ultrastructure was analyzed by transmission electron microscopy. TUNEL was studied using an in situ cell death detection kit and the expression of apoptotic molecules by immunohistochemistry. The data confirmed arrest of spermatogenesis and intense apoptotic processes of germ cells in hybrids. These animals also showed ultrastructural alterations in the Leydig cells. Fas, FasL and calbindin D28k overexpression without an increase in DNA fragmentation was detected in the Leydig cells from hybrids. In conclusion, the sterility of Graomys hybrids occurs with ultrastructural changes in germ and Leydig cells. The enhancement of Fas and FasL is not associated with cell death in the Leydig cells. Probably the apoptosis in these interstitial cells is inhibited by the high expression of the antiapoptotic molecule calbindin D28k.