Urinary time- or dose-dependent metabolic biomarkers of aristolochic acid-induced nephrotoxicity in rats

Abstract

The metabolicmechanisms underlying aristolochic acid (AA)-induced nephrotoxicity are inconclusive. A Gas Chromatography- Mass Spectrometer (GC-MS)-basedmetabolomic study was performed to analyze urinarymetabolites in AA-treated rats at different dosages (10, 20, and 40mg/kg) and time points (2, 4, and 6 days). Serum blood urea nitrogen (BUN), creatinine, and kidney injury were significantly changed only on the 6th day in 40mg/kg AA group, whereasmetabolic alternation appeared even on the 2nd day in 10mg/kg AA group. A total of 84 differential metabolites were identified in 40mg/kg AA groups timedependently and 81 in 10, 20, and 40mg/kg AA groups dose-dependently (6 days) compared with control group. Eightmetabolites were selected as potentialmetabolic biomarkers includingmethylsuccinic acid, nicotinamide, 3-hydroxyphenylacetic acid, citric acid, creatinine, uric acid, glycolic acid, and gluconic acid. Four of them were dose-dependently altered includingmethylsuccinic acid, citric acid, creatinine, and 3-hydroxyphenylacetic acid, which were defined as "earlymetabolic biomarker." The alteration of nicotinamide, uric acid, and gluconic acid was time- and dose-dependent, whereas the change of glycolic acid was time- or doseindependent. The latter 4metabolites were defined as "latemetabolic biomarker" because of the obvious reduction on the 6th day in 40mg/kg AA group. In summary, the urinarymetabolic alterations were more sensitive than conventional biomarkers of renal injury. The identifiedmetabolites suggested pathways of energy metabolism, gutmicrobiota, and purine metabolism were associated with AA-induced nephrotoxicity time- or dose-dependently. Further investigation was warranted to determine the roles of the 8 potential metabolic biomarkers in AA-induced nephrotoxicity.