Selective immunoneutralization of luteinizing hormone results in the apoptotic cell death of pachytene spermatocytes and spermatids in the rat testis

Abstract

The selective withdrawal of pituitary gonadotropins through specific antibodies is known to cause disruption of spermatogenesis. The cellular mechanism responsible for the degenerative changes under isolated effect of luteinizing hormone (LH) deprivation is not clear. Using antibodies specific to LH we have investigated the effect of immunoneutralization of LH on apoptotic cell death in the testicular cells of the immature and the adult rats. Specific neutralization of LH resulted in apoptotic cell death of germ cells, both in the immature and the adult rats. The germ cells from control animals showed predominantly high molecular weight DNA, while the antiserum treated group showed DNA cleavage into low molecular weight DNA ladder characteristic of apoptosis. This pattern could be observed within 24 h of a/s administration and the effect could be reversed by testosterone. The germ cells were purified by centrifugal elutriation and the vulnerability of germ cell types to undergo apoptosis under LH deprivation was investigated. The round spermatids and the pachytene spermatocytes were found to be the most sensitive germ cells to lack of LH and underwent apoptosis. Interestingly, spermatogonial cells were found to be the least sensitive germ cells to the lack of LH in terms of apoptotic cell death. Results show that LH, in addition to being involved in the germ cell differentiation, 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 spermatogenesis and the specific neutralization of gonadotropic hormones can be a reliable model for the study of the molecular mechanism of apoptosis.

Studies on the European hare. 56. Seasonal variation of testicular activity in European brown hare Lepus europaeus

“…The output of spermatozoa is determined largely by the shifts in degeneration vs survival of dividing and developing germ cells (Bartke 1995). The survival of spermatogenic cells is dependent on gonadotropins as well as on intratesticular androgens induced by LH (Tapanainen et al 1993, Troiano et al 1994, Billig et al 1995, Marathe et al 1995. Testosterone plays an essential role in preventing apoptotic cell death in androgen-dependent tissues (reviewed in Tenniswood et al 1992, Thompson 1994.…”

Hormonal regulation of male germ cell development

“…A recent study has reported the regulation of both the intrinsic and extrinsic pathway components, Bcl2l2, Casp8, and Casp9, in hpg mice at 13 dpp; however, the specific contribution of testosterone to this process is not known (Chausiaux et al 2008). In adults, several studies have shown that testosterone withdrawal from rat testis leads to an increase in meiotic and spermatogenic cell apoptosis in a stage-dependent manner, and suggested that testosterone may act as a survival factor (Billig et al 1995, Henriksén et al 1995, Marathe et al 1995, Bakalska et al 2004. Few studies have investigated the molecular mechanism by which testosterone affects germ cell apoptosis in rodents.…”

“…In immature rats, testosterone is an absolute requirement for the completion of the first wave of spermatogenesis during puberty (Cameron et al 1993, Marathe et al 1995. Similarly, AR Sertoli cell knockout mice have also displayed arrest at late spermatocytes and beyond (Chang et al 2004, De Gendt et al 2004, suggesting that the completion of meiosis and spermiogenesis is dependent on androgen action in the first wave.…”

“…The role that testosterone plays in germ cell survival during the first wave of spermatogenesis has not been explored in the last decade; however, studies have shown that testosterone regulates spermatocyte and spermatid survival in in vivo and in vitro conditions of immature rats (Tapanainen et al 1993, Marathe et al 1995. A recent study has reported the regulation of both the intrinsic and extrinsic pathway components, Bcl2l2, Casp8, and Casp9, in hpg mice at 13 dpp; however, the specific contribution of testosterone to this process is not known (Chausiaux et al 2008).…”

The effects of FSH and of testosterone on the completion of meiosis and the very early steps of spermiogenesis of the rat: an in vitro study

“…Indeed, what would seem to be a relatively simple question to answer has remained unclear. The elucidation of the role of each hormone in vivo requires perturbation of the system by a variety of experimental conditions: hypophysectomy (Ahmad et al 1975, Russell et al 1987, treatment with a gonadotropin-releasing hormone (GnRH) antagonist (Sinha Hikim & Swerdloff 1993, Billig et al 1995, immunoneutralization of gonadotropin (Marathe et al 1995, Shetty et al 1996 or GnRH (McLachlan et al 1995), treatment with ethane dimethanesulfonate, a cytotoxic compound for Leydig cells (Henriksen et al 1995) or steroid implants (McLachlan et al 1994), or use of specific animal models such as the hypogonadal mouse (O'Shaughnessy et al 1992) or mice rendered deficient in FSH (Kumar et al 1997) or FSH receptor (Dierich et al 1998) by knockout (KO) strategies. However, it has become clear that it is difficult in vivo to perturb testosterone production independently of gonadotropin secretion and reciprocally (Sinha Hikim & Swerdloff 1993, McLachlan et al 1994.…”