Mohammed F Hamad1, Wael A Abu Dayyih2, Mohammad Laqqan3, Yasir AlKhaled3, Mathias Montenarh4, Mohammed E Hammadeh3. 1. Department of Basic Sciences, College of Science and Health Professions, King Saud Bin Abdulaziz University for Health Sciences, Jeddah, Saudi Arabia; IVF and Andrology Laboratory, Department of Obstetrics and Gynaecology, Saarland University Hospital, Building 9, Homburg/Saar 66424, Germany; Department of Medical Biochemistry and Molecular Biology, Saarland University, Building 44, 66424, Homburg/Saar, Germany. Electronic address: hamadm@ksau-hs.edu.sa. 2. Department of Pharmaceutical Medicinal Chemistry and Pharmacognosy, Faculty of Pharmacy and Medical Sciences, University of Petra, Amman, Jordan. 3. IVF and Andrology Laboratory, Department of Obstetrics and Gynaecology, Saarland University Hospital, Building 9, Homburg/Saar 66424, Germany. 4. Department of Medical Biochemistry and Molecular Biology, Saarland University, Building 44, 66424, Homburg/Saar, Germany.
Abstract
RESEARCH QUESTION: Does regular smoking affect semen quality and the levels of DNA methylation in mature human spermatozoa? DESIGN: Spermatozoa from 109 men were evaluated (55 smokers and 54 non-smokers). DNA was extracted from purified spermatozoa, and DNA methylation was quantified by enzyme-linked immunosorbent assay (ELISA). RESULTS: Global DNA methylation of non-smokers is significantly lower (P < 0.001) than that of smokers (4.85 ± 2.72 and 7.08 ± 1.77 ng/μl, respectively). Moreover, the mean global DNA methylation levels were significantly correlated (r = 0.22;P = 0.02) with non-condensed chromatin in the spermatozoa. Levels of non-condensed chromatin were significantly higher (P < 0.001) in smokers (29.75 ± 9.38%) compared with non-smokers (20.96 ± 11.31%). Furthermore, global sperm DNA methylation was negatively correlated with high significance (P < 0.010) with sperm: count (r = -0.27), motility (r = -0.30) and vitality (r = -0.26). CONCLUSION: Smoking interferes with DNA methylation. Also, DNA methylation is significantly correlated with sperm parameters and sperm non-condensed chromatin. These data emphasize another detrimental effect of smoking on male fertility. DNA methylation may, therefore, be considered as a fertility marker in men.
RESEARCH QUESTION: Does regular smoking affect semen quality and the levels of DNA methylation in mature human spermatozoa? DESIGN: Spermatozoa from 109 men were evaluated (55 smokers and 54 non-smokers). DNA was extracted from purified spermatozoa, and DNA methylation was quantified by enzyme-linked immunosorbent assay (ELISA). RESULTS: Global DNA methylation of non-smokers is significantly lower (P < 0.001) than that of smokers (4.85 ± 2.72 and 7.08 ± 1.77 ng/μl, respectively). Moreover, the mean global DNA methylation levels were significantly correlated (r = 0.22;P = 0.02) with non-condensed chromatin in the spermatozoa. Levels of non-condensed chromatin were significantly higher (P < 0.001) in smokers (29.75 ± 9.38%) compared with non-smokers (20.96 ± 11.31%). Furthermore, global sperm DNA methylation was negatively correlated with high significance (P < 0.010) with sperm: count (r = -0.27), motility (r = -0.30) and vitality (r = -0.26). CONCLUSION: Smoking interferes with DNA methylation. Also, DNA methylation is significantly correlated with sperm parameters and sperm non-condensed chromatin. These data emphasize another detrimental effect of smoking on male fertility. DNA methylation may, therefore, be considered as a fertility marker in men.