Aging-related compensated hypogonadism: Role of metabolomic analysis in physiopathological and therapeutic evaluation

Aging is a complex process that increases the risk of chronic disease development. Hormonal and metabolic alterations occur with aging, such as androgen activity decrease. Studies aim to understand the role of testosterone replacement therapy (TRT) in males, however biomarkers and the metabolic responses to TRT are not well characterized. Therefore, the present study investigated TRT effect in young adult and aged rats by metabolomics. Male Wistar rats were divided into four groups: adult and adult + testo (6months), old and old + testo (25-27months). TRT animals received daily testosterone propionate (1 mg/kg/subcutaneous). TRT changed the testicular weight index decrease induced by aging but did not change the body weight and liver weight index. Sera were analyzed by liquid chromatograph high resolution mass spectrometry (LCMS/MS). Testosterone was quantified by target LCMS/MS. A total of 126 metabolites were detected with known identification altered by TRT by non-target metabolomics analysis. Multivariate statistics shows that all groups segregated individually after principal component analysis. The treatment with testosterone induced several metabolic alterations in adult and old rats that were summarized by variable importance on projection score, metabolite interaction and pathway analysis. Aging-related hypogonadism induces a pattern of systemic metabolic alterations that can be partially reversed by TRT, however, this treatment in aged rats induces novel alterations in some metabolites that are possible new targets for monitoring in patients submitted to TRT.