Increased renal semicarbazide-sensitive amine oxidase activity and methylglyoxal levels in aristolochic acid-induced nephrotoxicity

Abstract

AimsAristolochic acid (AA) nephrotoxicity is related to accumulation of methylglyoxal (MGO) and Nε-(carboxymethyl)lysine (CML) in the mouse kidney. We studied the activity of renal semicarbazide-sensitive amine oxidase (SSAO), a key enzyme involved in MGO generation, in AA-treated mice, and investigated nephroprotective effects produced by metformin, a MGO scavenger. MethodsMice were orally administered water or metformin for 15days (12 or 24mgkg−1day−1), and injected AA (5mgkg−1day−1) intraperitoneally for 8days starting on day 8. Renal function was studied, and histopathological examination, determination of renal SSAO activity, and measurement of MGO levels were performed. Key findingsCompared to control mice, AA-injected mice showed significant renal damage and approximately 2.7-fold greater renal SSAO activity (p<0.05). Further, compared to control treatment, administration of 12mg/kg metformin inhibited formation of renal lesions, and significantly decreased renal MGO levels (37.33±9.78 vs. 5.89±2.64μg/mg of protein, respectively, p<0.01). In the AA-treated mice, metformin also inhibited the accumulation of CML in renal tubules, but did not affect SSAO activity. SignificanceThis study is the first to show elevated renal SSAO activity in AA-treated mice, which could be involved in MGO accumulation. Moreover, MGO scavenging by metformin reduces AA nephrotoxicity. These findings suggest that reducing MGO accumulation produces nephroprotection, revealing new therapeutic strategies for the management. SSAO is a key enzyme involved in MGO generation, and consequently, inhibition of renal SSAO activity is worth investigating in AA nephrotoxicity and other renal pathologies further.