Date of Award
Bachelor of Science Honours
Faculty of Computing, Health and Science
Dr Peter Roberts
Dr Peter Burton
Male infertility is now recognised as a significant factor in couples having difficulty conceiving. The impact of maternal age has long been known as a limiting factor, however recent research indicates that advancing paternal age can also negatively impact on a couple's chances of conception. One of the major contributing causes of male infertility has now been linked to spermatozoa exposure to reactive oxygen species (ROS). Such exposure induces oxidative stress when coupled with reduced total antioxidant capacity (TAC). Measures of both ROS and TAC are used as tests of oxidative stress status (OSS) which are used together to give further insight into male fertility status. Current research has revealed that the level of DNA fragmentation increases with age and, due to their composition, the sperm plasma membrane, DNA double helix and single stranded DNA are highly susceptible to ROS attack. ROS cause high levels of lipid peroxidation (LPO) that ultimately damages the plasma membrane and interferes with its vital functions. ROS also readily attack the purine and pyrimidine bases of DNA resulting in DNA damage. It is hypothesized that advancing paternal age will impact negatively of levels of ROS, TAC and DNA fragmentation in ageing men. The aim of this study was to determine the relationship between ROS, TAC and DNA damage on spermatozoon viability in relation to age. Ejaculated semen samples from 54 men undergoing infertility assessment were collected and divided into men aged ≥40 years (n=16) and men aged ≤39 years (n=38). Samples were examined for their level of ROS and TAC as a possible indication of oxidative stress status. Samples were also assessed for DNA fragmentation and damage using TUNEL. Statistical analysis consisted of independent t-tests, chi-square tests and multivariate logistic regression. Analysis found no significant associations between ROS, TAC, TUNEL and age. Significant differences were observed between abnormal sperm motility and age (p<0.05; t-test and regression analysis) and between abnormal sperm concentration and TUNEL (p<0.05; chi-square test and regression analysis). The results obtained in this present study did not support the hypothesis that there is an association between age, ROS, TAG and TUNEL. Research has identified a negative correlation between the effects of ROS and reduced TAG and advancing age on male fertility. ROS, either alone or in combination with reduced TAG, has also been directly associated with an increase in DNA damage. An increase in the incidence of certain childhood cancers and disease has been linked to spermatozoon DNA damage. Future research should be directed toward exploring the influences of these factors in relation to advancing paternal age given the potential benefits extend beyond the couple and to any future offspring.
McAndrew, T. (2008). The Effects of Oxidative Stress and Age on Human Spermatozoa. Retrieved from http://ro.ecu.edu.au/theses_hons/1106