Researchers at the University of Sheffield and University of Nottingham have identified how cigarette smoke damages reproductive health at a molecular level in both men and women.
The study examined how different levels of cigarette smoke exposure affect the ovaries and testes. Male and female mice were exposed to cigarette smoke extract at lower or higher doses for 12 weeks. Researchers then studied the structure of the reproductive organs and measured gene activity in each.
Effects on female fertility
In females, the number and structure of ovarian follicles — where eggs develop — showed relatively little change following exposure, even at higher levels. However, smoke exposure reduced the activity of genes responsible for cell division and metabolism, while increasing the activity of genes that control protein production.
These shifts mirror biological changes typically seen in accelerated ovarian ageing and declining fertility in women.
Effects on male fertility
In males, higher levels of smoke exposure led to physical changes inside the testes, including enlargement of the seminiferous tubules where sperm develop. Genes regulating sperm production became overactive, while genes that protect against infection and inflammation became less active.
The results suggest that cigarette smoke directly disrupts essential biological processes for healthy testicular function and sperm development.
Research findings
Dr Adam Watkins, Senior Lecturer in Reproductive Medicine from the University of Sheffield School of Medicine and Population Health, said the research showed how differently the two organs responded to cigarette smoke.
"In the ovary, the overall structure of the tissue was unaltered, but the genes told a different story, we saw changes in those that regulate cell proliferation and protein synthesis," Dr Watkins said. "In the testis, the changes were visible in the tissue itself, with measurable differences in morphology, alongside altered expression of genes that regulate sperm production. These results suggest that the quality of the sperm and eggs produced might be compromised by smoking."
Professor Lucy Fairclough from the School of Life Sciences at the University of Nottingham added: "Our study has identified potential biological mechanisms that could help explain the link between smoking and reproductive health in both men and women."
Next steps
The research team will establish whether parental smoking reduces the ability of mice to become pregnant and whether the health of their offspring is affected.