Expression of apoptotic genes in testicular germ cells and their modulation by luteinizing hormone

Gonadotropins regulate spermatogenesis by promoting survival and differentiation of germ cells. The molecular markers that are modulated by these hormones to ensure survival however have not been described in great detail. Immunoneutralization of LH in particular leads to apoptotic cell death of the spermatocytes and the round spermatids. In the present study, the expression pattern and regulation of apoptotic markers after specific immunoneutralization of LH in germ cells purified from rats has been investigated at the RNA and protein level. Of the several markers tested, Bax, caspases 1 and 2 and Fadd exhibit differential expression, with the round spermatids expressing higher levels of caspases 1 and 2, and the spermatocytes expressing higher levels of Bax and Fadd. The two cell types therefore exhibit differential expression of apoptotic markers. The cell types also differ with respect to their response to LH antiserum treatment. Fas and Bax both are up-regulated in the round spermatids after 24h of antiserum treatment. In the spermatocytes, Fas was up-regulated as early as 12h after antiserum treatment while Bax was up-regulated after 2 days. These results demonstrate that LH regulates survival of germ cells by modulating the levels of pro and anti-apoptotic proteins.