8-Hydroxy-2′-deoxyguanosine in leukocyte DNA of spermatic vein as a biomarker of oxidative stress in patients with varicocele

Purpose: We examined oxidative damage to leukocyte DNA in the spermatic vein and sperm DNA of patients with varicocele. Materials and Methods: A total of 32 young male patients with varicocele (group 1), 20 young male patients with subclinical varicocele (group 2) and 15 normal young males without varicocele (group 3) were recruited in this study. Varicocele and subclinical varicocele were confirmed by physical examination and Doppler ultrasonography. Blood samples were drawn from peripheral and spermatic veins of controls and patients before varicocelectomy. The 8-hydroxy-2′-deoxyguanosine (8-OHdG) in leukocyte DNA and sperm DNA were measured by high performance liquid chromatography. The 4977 bp deletion of mitochondrial DNA (mtDNA) in spermatozoa was detected by polymerase chain reaction. Results: The mean 8-OHdG level ± SD in leukocyte DNA of spermatic veins was significantly higher than that of corresponding peripheral veins in groups 1 and 2 (12.39 ± 2.90 vs 7.11 ± 0.75/10⁶ deoxyguanosine for group 1 and 10.28 ± 2.43 vs 6.82 ± 0.62/10⁶ deoxyguanosine for group 2, p <0.001). The 8-OHdG level in leukocyte DNA of the spermatic vein and 8-OHdG in sperm DNA were highest in group 1 followed by those in groups 2 and 3, and correlated inversely with motility, morphology and density of spermatozoa. The incidence of 4977 bp deletion of mtDNA in sperm was 40.6%, 20% and 0% in groups 1, 2 and 3, respectively. These results indicate that oxidative stress in patients with varicocele or subclinical varicocele was greater than in healthy subjects. Conclusions: 8-OHdG in leukocyte DNA of the spermatic vein and in sperm DNA, and 4977 bp deletion of mtDNA in sperm might be useful markers for the assessment of oxidative stress in patients with varicocele and subclinical varicocele.