Cold exposure, gut microbiota, and hypertension: A mechanistic study

Cold exposure has been recognized as an important risk factor for hypertension, and altered gut microbiota has been reported to be associated with hypertension. We hypothesized that there is a plausible relationship between gut microbiota and cold-induced hypertension (CIH). Therefore, we explored the potential link between the gut microbiota and its metabolites with CIH. Male Sprague-Dawley (SD) rats were randomly divided into the normal temperature group (NT, 20 ± 2 °C) and the cold exposure group (CE, 4 ± 1 °C), and faecal bacteria cross-transplantation was performed after six weeks. We analyzed the gut microbiota of rats using the 16S rDNA sequence and measured the blood pressure of rats and the content of short-chain fatty acids in rat faeces. After six weeks of cold exposure, the CIH rat model was successfully established. The cold exposure reduced the diversity of the gut microbiota, increased the abundance of potentially pathogenic and conditionally pathogenic bacteria (e.g., Quinella, Rothia, and Senegalimassilia genera), and reduced the abundance of beneficial bacteria (e.g., Lactobacillus genus) and butyric acid-producing bacteria (e.g., Lachnospiraceae UCG-008 and Ruminococcaceae UCG-013 genera). Faecal bacteria cross-transplantation altered gut microbiota composition and regulated blood pressure levels. The NT group rats transplanted with CIH rats' faecal bacteria were enriched with certain conditional pathogenic bacteria such as Prevotellaceae UCG-003 genus. The CIH rats transplanted with faecal bacteria from the NT group rats were enriched with beneficial bacteria such as Bacteroides genus. In addition, we found a significant reduction in butyric acid levels in CIH rats, which may be related to the increase in blood pressure. In conclusion, CIH is associated with altered gut microbiota and reduced butyric acid. Our findings provide novel insights for the prevention and treatment of CIH by modulating the gut microbiota through supplementation of beneficial bacteria/butyrate.