With considerable concerns about the associations between metabolic disorders and agricultural biocides, there are scattered data suggesting that the triazole fungicide prothioconazole (PTC) at lower doses than the no observed adverse effect level of 5000 μg/kg/d possibly has the potential to disrupt glycolipid metabolism in mammals. Here, we investigated the effects of 50, 500, and 5000 μg/kg/d of PTC on glycolipid metabolism in mice following 8 weeks of administration via drinking water, with specific attention on brown adipose tissue (BAT) and white adipose tissue (WAT) in addition to the liver. We found that along with the increased serum triglyceride level in the 5000 μg/kg/d group, small fatty vacuoles occurred in livers in all treatment groups, indicating lipid accumulation. No change in WAT was observed, but PTC caused BAT whitening, characterized by adipocyte hypertrophy, more unilocular adipocytes with enlarged lipid droplets, reduced UCP1 levels, and down-regulated Doi2 expression, and even the dose of 50 μg/kg/d was effective. Transcriptomic analysis revealed immune inhibition and circadian rhythm disturbance in BAT from the 5000 μg/kg/d group, which are in agreement with BAT whitening and inactivation. On employing the C3H10T1/2 cells in vitro, we found that PTC treatment concentration-dependently promoted lipid accumulation in brown adipocytes, along with altered expression of thermogenesis-related and circadian genes. Taken together, our study shows that low doses of PTC caused BAT whitening, calling for much attention to the new target by pollutants.
Keywords: brown adipose tissue; circadian rhythm; lipid metabolism; prothioconazole; triazole fungicide.