Impacts of polyglycolic acid and analogues on glycolipid metabolism and circadian behavior in zebrafish

Abstract

For the past few years, new biodegradable polymers, such as polyglycolic acid (PGA) and polylactic acid (PLA), have been promising materials to solve the remarkable environmental issue, of microplastics (MPs) pollution. In this research, the impacts of five MPs, including PGA, PLA, polybutylene succinate (PBS), polyhydroxyalkanoate (PHA), and polybutylene adipate terephthalate (PBAT), were analyzed on zebrafish with different concentrations. We found that PGA and PLA at 1 mg/L did not have obvious effects on liver function, glucose level, and circadian rhythm in larvae. However, Exposure to PBS, PHA, and PBAT at 1 mg/L could cause mild pathological injury of the liver and decreased glucose levels. Furthermore, exposure to PBS, PHA, and PBAT at 100 mg/L caused abnormal early development and pathological injury of the liver, increased ALT and TG levels, as well as decreased glucose levels. The molecular explanation of this was the variational expression levels of genes related to many aspects of biochemical pathways, such as oxidative stress, apoptosis, endoplasmic reticulum stress, fatty acid oxidation, and glucose metabolism. Meanwhile, larvae exposed to PBS, PHA, and PBAT at 100 mg/L showed chaos in circadian behaviors, accompanied by the disturbed expression of clock genes. Overall, we observed a greater adverse effect of PBS, PHA, and PBAT relative to PLA and PGA when we compared the effects induced by five MPs at the same exposure concentration. Our study provided important data to evaluate the ecological risk of new biodegradable polymers.