SELECTIVE IMMUNONEUTRALIZATION OF LUTEINIZING-HORMONE RESULTS IN THE APOPTOTIC CELL-DEATH OF PACHYTENE SPERMATOCYTES AND SPERMATIDS IN THE RAT TESTIS

The selective withdrawal of pituitary gonadotropins through specific a ntibodies is known to cause disruption of spermatogenesis. The cellula r mechanism responsible for the degenerative changes under isolated ef fect of luteinizing hormone (LH) deprivation is not clear. Using antib odies specific to LH we have investigated the effect of immunoneutrali zation of LH on apoptotic cell death in the testicular cells of the im mature and the adult rats. Specific neutralization of LH resulted in a poptotic cell death of germ cells, both in the immature and the adult rats. The germ cells from control animals showed predominantly high mo lecular weight DNA, while the antiserum treated group showed DNA cleav age into low molecular weight DNA ladder characteristic of apoptosis. This pattern could be observed within 24 h of a/s administration and t he effect could be reversed by testosterone. The germ cells were purif ied by centrifugal elutriation and the vulnerability of germ cell type s to undergo apoptosis under LH deprivation was investigated. The roun d spermatids and the pachytene spermatocytes were found to be the most sensitive germ cells to lack of LH and underwent apoptosis. Interesti ngly, spermatogonial cells were found to be the least sensitive germ c ells to the lack of LH in terms of apoptotic cell death. Results show that LH, in addition to being involved in the germ cell differentiatio n, is also involved in cell survival and prevent degeneration of germ cells during spermatogenesis. Apoptotic DNA fragmentation may serve as a useful marker for the study of hormonal regulation of spermatogenes is and the specific neutralization of gonadotropic hormones can be a r eliable model for the study of the molecular mechanism of apoptosis.