Analysis of the impact of intracellular reactive oxygen species generation on the structural and functional integrity of human spermatozoa: lipid peroxidation, DNA fragmentation and effectiveness of antioxidants

Abstract

Exposure of human spermatozoa to nicotinamide adenine dinucleotide phosphate (NADPH) resulted in the dose dependent generation of reactive oxygen species (ROS) which, at a critical level of intensity, induced lipid peroxidation, DNA damage and a dramatic decline of sperm motility. This system was then used as a model for screening the ability of different antioxidants to combat oxidative stress created through the excessive intracellular generation of toxic oxygen products of metabolism. A variety of antioxidants that has previously been shown to be protective against extracellularly derived oxidants (e.g. superoxide dismutase, catalase, vitamin E, hypotaurine) were ineffective in this system. Albumin, however, could provide complete protection against NADPH induced oxidative stress via mechanisms that did not involve the suppression of the lipid peroxidation cascade but rather the inactivation of lipid peroxides generated during this process. Albumin did not protect against DNA damage induced by NADPH but was extremely effective at preventing DNA fragmentation arising from the suppression of glutathione peroxidase activity with mercaptosuccinate. These studies emphasize that the design of clinically effective antioxidant treatments will depend, critically, upon the source of the oxidative stress. For cases involving excessive intracellular ROS generation, albumin appears to be an important means of neutralizing lipid peroxide-mediated damage to the sperm plasma membrane and DNA.

The role of antioxidant therapy in the treatment of male infertility: an overview

“…It should also be stressed that in McKinney's study, 73 reduced lipid peroxidation was observed after the addition of pentoxifylline (dosages from 3.6 to 7.2 mmol l 21 ), and that in Okada's study 74 doses from 1 to 10 mmol l 21 led to preserved motility, due to reduced loss of curvilinear velocity and beat-cross frequency. [71][72][73][74] However, in 1998 Twigg et al 19 found no improvement in lipid peroxidation after the addition of 3.6 mmol l 21 of pentoxifylline.…”

“…Only four of these studies [28][29][30][31] found little or no effect on semen parameters, whereas beneficial effects were reported in the remaining 18 studies. 8,19,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] In vitro studies. Two studies by Aitken et al 8,32 on the effects of vitamin E showed that 10 mmol l 21 suppressed lipid peroxidation, leading to preserved motility in vitro, with a dose-dependent effect.…”

“…Twigg et al 19 found that an in vitro dose of 1 mmol l 21 of vitamin E had no effect on lipid peroxidation induced by nicotinamide adenine dinucleotide phosphate. Thus, it is possible that the effectiveness of vitamin E and other antioxidants on lipid peroxidation depends on the source of oxidative stress.…”

“…Kessopoulou et al, 1995 28 No effects (600 mg day 21 for 3 months, in vivo) Moilanen and Hovatta, 1995 29 No effects (600-1200 mg day 21 for 3 weeks, in vivo) Geva et al, 1996 30 No effects (200 mg day 21 for 3 months, in vivo) Vezina et al, 1996 35 Increased motility, morphology, viability; no effects on concentration (400 mg day 21 1 100-200 mg day 21 Se for 6 months, in vivo) Suleiman et al, 1996 36 Increased pregnancy rate, increased motility, reduced lipid peroxidation (300 mg day 21 for 6 months, in vivo) Kodama et al, 1997 37 Increased concentration, reduced DNA damage (200 mg vitamin C1200 mg vitamin E1GSH 400 mg every day for 2 months, in vivo) Hughes et al, 1998 38 Reduced DNA damage after Percoll preparation (30-60 mmol l 21 vitamin E, in vitro) Hughes et al, 1998 38 Increased DNA damage after Percoll preparation (300-600 mmol l 21 vitamin C1 30-60 mmol l 21 vitamin E, in vitro) Twigg et al, 1998 19 No effects on NADPH-induced lipid peroxidation (1 mmol l 21 , in vitro) Donnelly et al, 1999 39,40 Reduced H 2 O 2 -induced ROS production and DNA damage (40-60 mmol l 21 , in vitro) Rolf et al, 1999 31 No effects (800 mg vitamin E11000 mg vitamin C daily for 56 days, in vivo) Comhaire et al, 2000 41 Reduced ROS quantity; no effects on semen parameters (30 b-carotene1180 mg vitamin E daily for 3 months, in vivo) 38 Increased DNA damage after Percoll preparation (300-600 mmol l 21 vitamin C1 30-60 mmol l 21 vitamin E, in vitro) Verma and Kanwar, 1998 34 Preserved motility (800 mmol l 21 , in vitro) Donnelly et al, 1999 39,40 Reduced H 2 O 2 -induced ROS production and DNA damage (300-600 mmol l 21 , in vitro) Rolf et al, 1999 31 No effects (800 mg day 21 vitamin E11000 mg day 21 To be continued…”

“…The presence of too many variables in most studies that focus on antioxidants and male infertility has also led to controversy, [17][18][19] not only because the authors have used different antioxidants, different combinations and different doses in patients with differing characteristics, but also because of the different end points evaluated in their studies. An improvement in sperm quality does not always translate into clinical benefit.…”