Project Two 2012: Oxidative stress in male infertility
Male infertility is present in a third of couples attending IVF clinics in Australia and combined male and female causes occur in another 40% of couples. In a high number of these cases the cause of the male infertility is not known. In recent years it has become apparent that a harmful process known as oxidative stress can cause male infertility. Specifically, increased oxidative stress levels are associated with abnormal sperm movement, increased sperm DNA damage and decreased fertility levels. Oxidative stress occurs in the body when damage to the cells (including sperm) is caused by the production of harmful molecules called “free radicals”. Male fertility is also known to decrease with advancing age and 40% of females who had IVF treatment at Concept in 2009 had partners who were aged over 40 years and 5% were over 50. So in study one in this series we will examine the role of oxidative stress in the relationship between age and male infertility. This study specifically investigates the question of whether oxidative stress in the sperm increases in older men. We will also examine whether the level of oxidative stress in the sperm is related to successful IVF outcomes and if this is affected by the age of the male partner.
It has recently been shown that high levels of sperm DNA damage is associated with lower pregnancy rates following IVF. In study two of this series we will examine sources of DNA damage in the sperm of fertile and infertile men, and the association between types of DNA damage and lifestyle factors such as smoking and length of the abstinence period.
Psychological stress is known to adversely affect fertility in both animals and humans but the mechanisms through which stress affects fertility are not known. In study three of this series we aim to find out whether the stress effect on male fertility is due to stress hormones causing an increase in oxidative stress in the sperm as they do in other areas of the body. In this experiment we will test whether cortisol (a stress hormone also present in semen) directly increases oxidative stress in human sperm. We will also examine whether cortisol levels in the semen are related to oxidative stress levels in fertile and infertile men.
These projects are being conducted by; Su-Ann Koh (PhD student, The University of Western Australia), Nicole Marjanovich (honours student, The University of Western Australia) and Gerard Chan (honours student, The University of Western Australia) under the supervision of Dr Burton and Assistant Professor Sanders.
In another related PhD project recently completed by Dr Gwyneth Gladstones in collaboration with Dr Burton and Dr Roberts at Edith Cowan University we showed that stress hormones cause oxidative stress in the epididymis (sperm maturation and storage area) which may affect the ability of sperm to mature and be able to fertilize the egg.