The antioxidant tempol reduces obesity in mice by altering the intestinal microbiota, suggests a paper published in Nature Communications this week. The study presents another example of the involvement of the gut microbiota in both drug action and regulation of body weight and highlights a signalling pathway in the intestine that could prove a useful target for anti-obesity drugs.

Frank Gonzalez and colleagues treated mice with tempol and detected a shift in the major groups of microbes present in the intestine. This shift led to a reduction in the activity of a microbial enzyme involved in taurine-conjugated bile acid degradation, and accordingly bile acid levels in the intestine increased during treatment. Taurine-conjugated bile acids are known to negatively affect FXR signalling - a pathway that is involved in bile acid, lipid and glucose metabolism. While it is not yet clear whether tempol would have any effect on human obesity or the gut microbiota, this study provides a possible mechanism for explaining how tempol affects obesity in mice and suggests that the FXR signalling pathway may be a suitable target for the treatment of metabolic disease.