Preclinical research shows tobacco smoke exposure alters reproductive organs across sexes—affecting ovarian gene activity and testicular tissue structure.
RT’s Three Key Takeaways:
- Sex-Specific Biological Responses: Researchers found that cigarette smoke exposure disrupts reproductive organs through distinct pathways in males and females, altering ovarian gene activity while inducing physical tissue changes in the testes.
- Ovarian and Testicular Changes: The preclinical study revealed that smoke exposure reduced the expression of genes tied to cell division in ovaries, mirroring accelerated aging, while enlarging seminiferous tubules and dampening protective immune genes in testes.
- Mechanisms Behind Infertility: The findings provide healthcare providers and researchers with cellular insights into how tobacco smoke degrades sperm and egg quality, helping explain molecular contributors to global infertility.
Exposure to cigarette smoke directly alters biological processes critical to ovarian function and sperm production, according to a preclinical study published in Frontiers in Toxicology.
According to the World Health Organization (WHO), approximately one-in-six people globally experience infertility during their lifetime. Although smoking represents an established clinical risk factor for reproductive impairment, the underlying molecular mechanisms within ovaries and testes have remained poorly understood, according to researchers from the University of Sheffield and the University of Nottingham.
To evaluate these pathways, researchers exposed male and female mice to low or high doses of cigarette smoke extract for 12 weeks, subsequently evaluating organ structure and measuring gene activity in ovarian and testicular tissues.
Divergent Effects on Male and Female Reproductive Tissues
In female models, researchers observed that the count and structural architecture of ovarian follicles remained largely unchanged following smoke exposure, even at higher doses. However, the exposure significantly decreased the activity of genes involved in cell division and metabolism, while elevating the expression of genes controlling protein production—shifts that mirror biological markers of accelerated ovarian aging and declining fertility in women.
In male models, higher levels of smoke exposure led to physical alterations inside the testes, including enlargement of the seminiferous tubules where sperm develop. Furthermore, genes regulating sperm production became overactive, whereas genes responsible for defending against inflammation, cellular injury, and infection showed reduced activity, indicating that smoke exposure disrupts processes required for healthy testicular function.
“While it’s well-established that smoking is harmful to people’s reproductive health, exactly how it does this is not fully understood. What this research interestingly showed is how differently the two organs responded to cigarette smoke,” said Dr Adam Watkins, senior lecturer in reproductive medicine from the University of Sheffield School of Medicine and Population Health.
“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,” said Watkins. “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.”
Clinical and Research Implications
The investigators noted that while the research evaluated animal models, the data provide important insight into the mechanisms connecting tobacco exposure with reproductive outcomes in humans.
“Our study has identified potential biological mechanisms that could help explain the link between smoking and reproductive health in both men and women,” said Lucy Fairclough, professor from the School of Life Sciences at the University of Nottingham, in a news release. “In females, we identified changes in gene activity associated with biological processes that have previously been linked to ovarian ageing and reduced ovarian function. In males, we found changes in genes involved in sperm production and testicular function.”
According to the research team, future investigations will focus on whether parental exposure to cigarette smoke decreases pregnancy success rates, impairs embryonic development, and affects the long-term health of offspring.
