NOTTINGHAM AND SHEFFIELD STUDY LINKS SMOKING TO FERTILITY GENE CHANGES

Researchers at the University of Nottingham and the University of Sheffield have identified gene changes in mice exposed to cigarette smoke that could help explain how smoking affects the ovaries and testes, according to a study published in the journal Frontiers. The scientists examined the structure of the ovaries and testes, along with gene activity, in mice exposed to cigarette smoke extract at lower and higher doses over 12 weeks. In female mice, the number and structure of ovarian follicles, where eggs develop, showed little change even after high exposure to cigarette smoke, the researchers said. However, they identified gene changes similar to those seen in biological processes linked to ovarian ageing and reduced ovarian function. In male mice, higher levels of smoke exposure were associated with changes to testicular structures, including enlargement of the seminiferous tubules where sperm develop, along with altered activity in genes involved in sperm production, immune responses and cell signalling.

According to the World Health Organisation, about one in six people worldwide experience infertility at some point in their lives, the researchers noted. Links between smoking and reduced fertility are already well established, but how smoking affects the ovaries and testes at a biological level has not been well understood, according to the study. The researchers said some genes involved in sperm production became more active following smoke exposure, while some genes involved in immune function became less active. They said the findings suggest that cigarette smoke exposure may alter biological processes important for normal testicular function and sperm development.

Professor Lucy Fairclough of the University of Nottingham, a co-author of the study, said the research had identified potential biological mechanisms that could help explain the link between smoking and reproductive health in both men and women. She said the team had identified changes in gene activity in female mice associated with biological processes previously linked to ovarian ageing and reduced ovarian function. The researchers said the gene changes found in both male and female mice add to limited existing understanding of how smoking affects reproductive organs. The study was carried out on mice, and the researchers presented the findings as a step towards explaining the established link between smoking and fertility in humans.