High temperature and humidity in the environment disrupt bile acid metabolism, the gut microbiome, and GLP-1 secretion in mice.

High temperature and humidity in the environment are known to be associated with discomfort and disease, yet the underlying mechanisms remain unclear. We observed a decrease in plasma glucagon-like peptide-1 levels in response to high-temperature and humidity conditions. Through 16S rRNA gene sequencing, alterations in the gut microbiota composition were identified following exposure to high temperature and humidity conditions. Notably, changes in the gut microbiota have been implicated in bile acid synthesis. Further analysis revealed a decrease in lithocholic acid levels in high-temperature and humidity conditions. Subsequent in vitro experiments demonstrated that lithocholic acid increases glucagon-like peptide-1 secretion in NCI-H716 cells. Proteomic analysis indicated upregulation of farnesoid X receptor expression in the ileum. In vitro experiments revealed that the combination of lithocholic acid with farnesoid X receptor inhibitors resulted in a significant increase in GLP-1 levels compared to lithocholic acid alone. In this study, we elucidate the mechanism by which reduced lithocholic acid suppresses glucagon-like peptide 1 via farnesoid X receptor activation under high-temperature and humidity condition.

Combined LC-MS/MS and 16S rDNA analysis on mice under high temperature and humidity and Herb Yinchen protection mechanism.

With increased global warming, the impact of high temperature and humidity (HTH) on human health is increasing. Traditional Chinese medicine describes the Herb Yinchen as a remedy for reducing heat and eliminating dampness. This study focused on the impact of HTH conditions on mice and the potential protective effect of Herb Yinchen. Five male Balb/c mouse groups included two normal control groups, two HTH-exposed groups, and one Yinchen-treated group. For either three or ten days, normal and HTH-exposed mice were housed under normal or HTH (33 ± 2 °C,85% relative humidity) conditions, respectively. Yinchen-treated mice, housed under HTH conditions, received the Herb Yinchen decoction for three days. Metabolite profiles of plasma and liver samples from each group were analyzed using LC-MS/MS. Fecal DNA was extracted for 16S rDNA analysis to evaluate the intestinal microbiome. Spearman correlation analysis was performed on metabolites, bacteria, and bile acids that differed between the groups. We found that HTH altered the host metabolite profiles and reduced microbial diversity, causing intestinal microbiome imbalance. Interestingly, Herb Yinchen treatment improved HTH-mediated changes of the metabolite profiles and the intestinal microbiome, restoring them to values observed in normal controls. In conclusion, our study reveals that HTH causes intestinal bacterial disturbances and metabolic disorders in normal mice, while Herb Yinchen could afford protection against such changes.