Objective  Nanoparticles (NPs) in haze are potentially hazardous to health, which is more severe in the winter. Brown adipose tissue (BAT) plays important roles in obesity, insulin resistance, and diabetes. Though the toxicology of NPs has been intensively studied, few studies have been reported on the antagonistic effects between Silicon dioxide(SiO₂) NPs and cold exposure in brown adipocytes.  Materials and methods  We evaluated changes by quantitative real-time reverse-transcriptase polymerase chain reaction (qRT-PCR) on metabolism genes, plasticity genes and the inflammatory responses genes in brown adipocytes in vitro.  Results  The expression of adipogenic genes PRDM16, Dio2, PGC-1α and UCP1 was upregulated upon cold exposure (P < 0.05), but downregulated by SiO₂ NPs (P < 0.05). The results demonstrated that there was antagonistic effect between SiO₂ NPs and cold exposure on the plasticity genes and metabolism genes in brown adipocytes, where the main effects of SiO₂ NPs or cold exposure on the plasticity genes and metabolism genes were significant (P < 0.05). Moreover, the levels of interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α were upregulated by SiO₂ NPs or cold exposure (P < 0.05). The factorial analysis indicated that there was also antagonistic effect between SiO₂ NPs and cold exposure on the toxic effects in brown adipocytes, in which the main effects of cold exposure and/or SiO₂ NPs on the toxic effects were significant (P < 0.05).  Conclusion  SiO₂ NPs inhibit the effect of cold exposure on metabolic genes and inflammatory responses genes in brown adipocytes.

The gut microflora is a combination of all microbes in intestine and their microenvironment, and its change can sensitively reflect the relevant response of the body to external environment and remarkably affect body's metabolism as well. Recent studies have found that cold exposure affects the body's gut microflora, which can lead to changes in the body's metabolism of glucose and lipid. This review summarizes recent research on the effects of cold exposure on gut microbes and metabolism of glucose and lipid, aiming to provide some new ideas on the approaches and measures for the prevention and treatment of diabetes and obesity.