Abstract

Sperm DNA quality is important in male fertility. Oxidative stress increases sperm DNA damages. Antioxidants decrease production of free radicals and scavenge them. Nitric oxide (NO) is a free radical which is produced by most cells and has a dual role on cells. Low concentrations of NO is essential in biology and physiology of systems but high level of NO has a detrimental effect on cells. The aim of this study was to determine the role of the nitric oxide concentration and total antioxidant capacity (TAC) in seminal plasma with sperm DNA damage. Semen samples from 45 infertile men and 70 normozospermic men were examined for DNA damage, nitric oxide concentration and TAC. DNA damage was measured by comet assay and nitric oxide concentration was evaluated by Griess assay. TAC was measured in seminal plasma based on the generation of peroxyl radicals from 2,2-azinobis (2-amidino propane) dihydrochlorid (AAPH). Our results show that the means of DNA damage and nitric oxide concentration in infertile men was higher than fertile men. TAC level in infertile men was significantly lower than fertile men. DNA damage was significantly correlated with nitric oxide concentration in infertile men (p = 0.001, r = +0.598) and TAC (p = 0.04, r = - 0.3) in infertile men. In conclusion, sperm DNA damage in infertile men may be induced by nitric oxide-mediated oxidative stress and low levels of TAC.

Key words: Nitric oxide, male infertility, total antioxidant capacity, DNA damage.

Abbreviation

Abbreviations: GPX, Glutathione peroxidase; GRD, glutathione reductase; ROS,reactive oxygen species; TAC, total antioxidant capacity; FAD, flavin adenine dinucleotide; NADPH, nicotinamide adenine dinucleotide phosphate; NOS, nitric oxide synthase; nNOS, neuronal NOS; iNOS, inducible NOS; eNOS, endothelial NOS.