Comparative analysis of the ability of precursor germ cells and epididymal spermatozoa to generate reactive oxygen metabolites

Abstract

Male germ cells at various stages of differentiation from pachytene spermatocytes to mature caudal epididymal spermatozoa were examined for their ability to generate reactive oxygen species (ROS) using sensitive chemiluminescence techniques. In general, spermatozoa were found to spontaneously generate hydrogen peroxide as they progressed through the epididymis, maximal activity being observed on the release of mature cells from the caudal region into a modified Krebs‐Ringer's solution. The spontaneous production of hydrogen peroxide rose rapidly during the first 10 min after the spermatozoa had been diluted into culture medium and thereafter stabilized, neither phorbol esters nor A23187 subsequently influencing this activity. Low levels of superoxide generation were also detected in suspensions of epididymal spermatozoa, but did not correlate with maturation status. However, superoxide production could be dramatically enhanced by the addition of exogenous NADPH, in a manner that was closely correlated with the stage of epididymal development being maximal for immature cells recovered from the caput epididymis in all species. Precursor germ cells (pachytene spermatocytes, round and elongate spermatids) similarly generated chemiluminescent signals compatible with the low level generation of ROS. Superoxide generation in these cells could again be stimulated by NADPH, via mechanisms that were inversely related to the stage of germ cell differentiation, the greatest activity being observed in pachytene spermatocytes. These results demonstrate that differentiating male germ cells have the potential to generate ROS, and have implications for the redox regulation of gonadal function and the development of reproductive pathologies involving oxidative stress. J. Exp. Zool. 277:390–400, 1997. © 1997 Wiley‐Liss, Inc.

Impact of a mild scrotal heat stress on DNA integrity in murine spermatozoa

“…The effects of oxidative stress on the genomic integrity of spermatozoa have been studied by inducing oxidative stress in the testis and in mature spermatozoa (Aitken et al 1989, Lucesoli & Fraga 1995. Within the testis a number of cell types produce high levels of reactive oxygen species (ROS) that may result in oxidative damage to DNA, proteins and cell membranes and to combat this, the testis has developed a very complex antioxidant system (Bauche et al 1994, Fisher & Aitken 1997. Therefore decreased expression of oxidative stress response genes, including extracellular superoxide dismutase (SOD) 3, manganese SOD 2 and genes involved in the metabolism of glutathione, which has been reported to occur following heating, may leave cells more susceptible to oxidative DNA damage (Barroso et al 2000, Rockett et al 2001 A number of DNA repair mechanisms have been documented to be active during spermatogenesis (Richardson et al 2000, Aguilar-Mahecha et al 2001, Aitken & Krausz 2001, Rockett et al 2001, Hsai et al 2003.…”

Apurinic/Apyrimidinic Endonuclease (APE/REF-1) Haploinsufficient Mice Display Tissue-specific Differences in DNA Polymerase β-Dependent Base Excision Repair

“…We have established previously that oxidative stress is capable of inducing the ␤-pol-mediated BER pathway in various tissues (52). Furthermore, in response to an active state of spermatogenesis, there is a constant level of oxidative stress in testes (62,63), and unrepaired oxidative damage has been shown to induce abnormal sperm with reduced fertility (64). However, recent reports (65) have indicated that nuclear DNA of human spermatozoa is relatively resistant to damage induced by H 2 O 2 and iron treatment in vitro.…”

Role of reactive oxygen species in the pathophysiology of human reproduction

“…Thus, the impact of ROS on male fertility is a question of degree rather than the presence or absence of the pathology. A study by Fisher and Aitken (26) has indicated that male germ cells at various stages of differentiation from pachytene spermatocytes to mature caudal epididymal spermatozoa from mature male rats, mice, hamsters, and guinea pigs have the potential to generate ROS. Clear evidence also suggests that human sperm can produce ROS (27,28).…”