Acute in vitro exposure to environmentally relevant atrazine levels perturbs bovine preimplantation embryo metabolism and cell number.

Atrazine is a widely used herbicide known to negatively alter endocrine systems and perturb metabolism. Preimplantation exposure to pesticides may adversely affect long-term health, however few studies examine the effect of environmental levels and whether specific periods of development are particularly sensitive. In this study, the effect of acute, preimplantation atrazine exposure (days 3.5-7.5 post-fertilization) at levels detected and deemed safe in drinking water (0.02 and 20 μg/L respectively) on in vitro bovine embryo development, quality, metabolism, and gene expression was investigated. Atrazine exposure had no effect on development or quality, but significantly reduced blastocyst total cell numbers, attributable to a decrease in trophectoderm cells. Notably, atrazine (20 μg/L) markedly increased carbohydrate metabolism. Therefore, short-term exposure to environmentally relevant atrazine concentrations perturbs bovine preimplantation embryo metabolism and cell number, highlighting a potential mechanism by which atrazine can mediate embryo viability and health.