Combined Effects of Ambient PM2.5 and Cold Exposure on the Development of Metabolic Disorder

Abstract

The coexistence of temperature changes and air pollution poses a severe global environmental issue, exacerbating health burdens. The aim of this study was to clarify the combined effects of ambient PM2.5 and cold exposure on the development of metabolic disorders. Male C57BL/6 mice were randomly divided into four groups: TN-FA, TN-PM, TC-FA and TC-PM. The mice were then exposed to concentrated PM2.5 or filtered air (FA) under normal (22 °C) or cold (4 °C) environment conditions for 4 weeks. Metabolic-disorder-related indicators, blood pressure, serous lipids, fasting blood glucose and insulin, energy metabolism, mitochondria and protein expression in tissues were detected for comprehensively assessing metabolic disorder. The results showed that, compared to being exposed to PM2.5 only, when mice were exposed to both PM2.5 and the cold (non-optimal), they exhibited more significant metabolic disorders regarding glucose tolerance (p < 0.05), insulin resistance (p < 0.05), lipid metabolism, adipocytes (p < 0.01) and mitochondrial function. This study suggested that a cold environment might substantially exacerbate PM2.5-induced metabolic disorder. The interaction between temperature changes and air pollution implied that implementing the necessary environment-related policies is a critical and complex challenge.