Male castration alters the gut microbiota, leading to increased serum levels of branched-chain amino acids and adiposity

Abstract

Background: Testosterone deficiency is positively correlated with fat accumulation and obesity-related comorbidities, such as metabolic syndrome. Castration of young males is widely used in the cattle industry to improve meat quality. However, the mechanism linking hypogonadism and host metabolism is not clear. We aimed to evaluate the effect of male hypogonadism on the gut microbiota and serum metabolites, and the contribution of the altered microbiota to the host metabolic phenotype during hypogonadism. Results: We used metataxonomic and metabolomic approaches to evaluate the intestinal microbiota and host metabolism in male, castrated male (CtM), and female cattle. We then used a male mouse castration model to evaluate the causative factor(s) that underpin the alteration of the intestinal microbiota and host metabolic phenotype in response to hypogonadism. After pubescence, the CtM cattle harbored distinct ileal microbiota dominated by the family Peptostreptococcaceae, and exhibited distinct serum and muscle amino acid profiles (i.e., highly abundant branched-chain amino acids), with increased extra- and intramuscular fat storage. Castration of male mice phenocopied both the intestinal microbial alterations and obese-prone metabolism observed in cattle. Antibiotic treatment and fecal microbiota transplantation experiments in a mouse model further revealed that the intestinal microbial alterations associated with hypogonadism are a key contributor to the obese phenotype in the CtM animals. Conclusions: We demonstrated altered gut microbial profiles in the hypogonadal animals, with a negative feedback between the serum testosterone levels and the ileal abundance of Peptostreptococcaceae, and a distinct metabolic phenotype, with an enhanced amino acid metabolism. These findings suggest targeting the gut microbiota as a potential therapeutic strategy for the treatment of both hypogonadism and obesity.