Background:
In Australia, heavy use of the herbicide atrazine has led to widespread water and soil contamination. The reproductive health impacts of long-term low-level exposures to this environmental toxicant are unknown. Therefore, this study aimed to evaluate the effects of multi-generational exposure to environmental concentrations of atrazine on the ovary.
Method:
Female C57/Bl6 mice were continuously exposed to atrazine an environmentally relevant atrazine concentration (0.02 ng/ml) or control (DMSO vehicle control) via drinking water for 2 generations and ovaries were collected from generation 2 mice at 6 months of age (n=6/treatment/age). The numbers of healthy and atretic follicles were determined, and DNA, protein and lipid oxidative damage was assessed by immunostaining for 8-oxo-G, 4-HNE and NTY, respectively. In addition, oxidative stress related genes Sod1, Sod2, Ucp2, Cat and Gpx3 were examined using qRT-PCR.
Results:
The number of primordial follicles were significantly decreased, and atretic antral follicles increased, in 6-month-old atrazine-exposed generation 2 mice compared to controls, while no changes in the number of healthy primary, secondary, and antral were observed. The percentages of follicles positive for markers of oxidative stress induced damages in DNA, protein, lipid oxidation, were significantly increased in atrazine-exposed generation 2 mice compared to controls, as well as for late-stage apoptosis. The mRNA levels for antioxidant genes Cat and Gpx3 were also altered in atrazine-exposed generation 2 mice compared to controls.
Conclusion:
These data suggest that continuous multi-generational exposure of mice to low environmental levels of atrazine prematurely depletes the ovarian reserve, and increases follicular atresia, possibly through the induction of intra-ovarian oxidative stress. Understanding the impact of pervasive environmental toxicants, like atrazine, on female health is crucial to prevent reproductive disorders and diseases in current and future generations.