Protective and Therapeutic Effects of Licorice in Rats With Acute Tubular Necrosis

OBJECTIVES: Various protective and therapeutic effects such as antioxidant, anti-inflammatory, anticancer, antihistaminic, and antibacterial effects have been depicted for licorice. However, its biological effects in the kidney are still not clear. Therefore, we aimed to investigate the efficiency of licorice in rats with gentamicin (GM)-induced acute tubular necrosis. DESIGN AND METHODS: Rats were randomized into the control group (only saline for 12 days), licorice group (licorice for 12 days), GM group (GM for 12 days), GM + licorice group, and licorice-treated GM group (licorice for 12 days after taking GM for 12 days). Blood urea, creatinine, and uric acid levels were measured and histopathological analyses of the kidneys were performed. The oxidative side of oxidant-antioxidant balance was evaluated by detecting lipid peroxidation (LPO) and total peroxide levels, and antioxidative side was determined by measuring total antioxidant capacity (TAC) and reduced glutathione (GSH) levels in plasma and kidney tissues. RESULTS: The oxidant-antioxidant balance seemed to be shifted to the oxidative side in the GM group when compared with the control and GM + licorice groups. In GM group, biochemical profiles showed a remarkable increase in blood uric acid, urea, and creatinine levels, and depletion of renal tissue and plasma TAC and GSH levels. In addition, histopathologic studies revealed severe acute tubular necrosis, congestion, and hyaline casts, verifying GM-induced nephrotoxicity. Licorice was effective in reduction of blood urea, creatinine, and uric acid levels, and also effective in decreasing the tubular necrosis score. Licorice treatment also significantly reduced LPO and total peroxide levels, and increased TAC and GSH levels in both renal tissue and blood. Moreover, these changes in rats subjected to the combined therapy (GM + licorice) were significantly less than those of GM group. CONCLUSIONS: Licorice ameliorates GM-induced nephrotoxicity and oxidative damage by scavenging oxygen free radicals, decreasing LPO, and improving antioxidant defense.