Mice study reveals distinct ovarian and testicular gene changes from smoke

Exposure to cigarette smoke triggers distinct biological alterations in the reproductive organs of mice, according to a new study published in Frontiers. Researchers from the Universities of Nottingham and Sheffield identified specific changes in gene activity within both ovaries and testes, offering insight into mechanisms that may link smoking to reduced fertility in humans.

Infertility statistics and study scope

The World Health Organization estimates that approximately one in six people globally experience infertility during their reproductive years. To investigate potential causes, the research team utilized a mouse model to examine how varying levels of smoke exposure impact reproductive tissues. The study focused on structural changes and the activity of genes responsible for normal ovarian function and sperm production.

Ovarian response to smoke exposure

In female subjects, the physical structure and number of ovarian follicles—where eggs develop—remained largely unchanged even after higher levels of smoke exposure. However, significant shifts occurred at the genetic level. Genes governing cell division and metabolism showed reduced activity, while those associated with protein production became more active. This pattern of gene expression mirrors biological processes previously linked to ovarian ageing and diminished function.

Testicular changes and sperm development

Male mice exhibited different responses, particularly at higher exposure levels. Researchers observed structural modifications in the testes, including the enlargement of seminiferous tubules, the sites of sperm development. Gene activity related to sperm production, immune responses, and cell signalling also shifted. Some genes involved in sperm creation increased in activity, whereas those regulating immune function decreased, suggesting smoke alters critical processes for testicular health.

Expert commentary on mechanisms

Professor Lucy Fairclough from the University of Nottingham’s School of Life Sciences noted that the findings help explain the connection between smoking and reproductive health. She emphasized that while the study identifies potential biological mechanisms, further research is required to determine how these specific changes translate to human fertility outcomes.

Dr Adam Watkins from the University of Sheffield highlighted the divergent reactions between the sexes. He stated that while it is well-established that smoking harms reproductive health, the exact mechanisms remain unclear. His comments pointed out that the ovary maintained its structural integrity despite genetic changes, whereas the testis showed measurable morphological alterations alongside shifts in genes regulating sperm production.

The researchers conclude that these findings add to existing evidence regarding smoking's impact on reproduction. They underscore the necessity for deeper understanding of the biological pathways through which parental smoking affects reproductive health.