Cigarette smoke affects male and female fertility in mice

New research using mice may reveal how smoking affects reproductive health via different mechanisms in men and women.

Researchers in England used a mouse model to investigate the effects of smoking on male and female reproductive health, focusing on gene activity and structural changes in the ovaries and testes. They found that male and female reproductive tissues respond differently to cigarette smoke and were affected by different biological processes.

'While it is well-established that smoking is harmful for your reproductive health, the exact mechanisms are not fully understood,' said Dr Adam Watkins from the University of Sheffield, co-senior author of the study published in Frontiers in Toxicology. 'Our mouse study has enabled us to explore how the ovaries and testes respond following exposure to cigarette smoke.'

Male and female mice were exposed to a higher or lower dose of cigarette smoke extract for 12 weeks. In female mice, they observed little change in the number or structure of ovarian follicles. However, changes in gene expression similar to processes associated with ovarian ageing were observed. Genes involved in cell division and metabolism became less active, and genes involved with protein production became more active.

In male mice, high cigarette smoke extract caused changes in testicular structure, including enlargement of seminiferous tubules, where sperm development occurs. The researchers also observed changes in the expression of genes involved in sperm production, cell signalling and immune responses, suggesting that cigarette smoke exposure may hinder testes' normal function and sperm development.

Co-senior author Professor Lucy Fairclough from the University of Nottingham said the research had 'identified potential biological mechanisms that could help explain the link between smoking and reproductive health in both men and women.'

Previous research had already linked smoking to poorer fertility outcomes. The purpose of this study was to use the mouse model to identify patterns and generate hypotheses about which cellular pathways contribute to smoke-associated reproductive toxicity.

'These findings are important because they help us understand how exposure to cigarette smoke could affect reproductive health. Further research will be needed to establish how these biological changes relate to fertility in humans,' said Professor Fairclough.