Polystyrene Microplastics Affect the Reproductive Performance of Male Mice and Lipid Homeostasis in Their Offspring

The potential health risks of microplastics (MPs) to humans and other mammals have attracted global attention. However, whether long-term exposure to environmentally relevant doses of MPs could impair the reproductive functions of mammals and cause transgenerational effects on their offspring remains largely unclear. Our study revealed that long-term (i.e., 21 weeks) exposure to environmentally relevant doses of polystyrene MPs (40–100 μm) not only significantly decreased testicle relative weight but also decreased sperm quality (i.e., decreased sperm number and changed sperm phenotype), thus affecting the reproductive performance of male mice. The exposure also dysregulated lipid metabolism in their F1 offspring by altering 17 of 23 lipid classes. In particular, three lipid classes were closely related to non-alcoholic fatty liver disease; i.e., levels of alkylphosphatidylcholine, alkenylphosphatidylcholine, and alkenylphosphatidylethanolamine were significantly increased in the liver and plasma of F1 offspring. The lipid metabolism disruption also exhibited a dose-, gender-, and tissue-specific pattern. Our findings demonstrate for the first time the in vivo evidence of the male reproductive effects of exposure to environmentally relevant doses of MPs on terrestrial mammals and transgenerational effects on their offspring.