Curcumin inhibits adenosine deaminase and arginase activities in cadmium-induced renal toxicity in rat kidney

Abstract

In this study, the effect of enzymes involved in degradation of renal adenosine and l-arginine was investigated in rats exposed to cadmium (Cd) and treated with curcumin, the principal active phytochemical in turmeric rhizome. Animals were divided into six groups (n = 6): saline/vehicle, saline/curcumin 12.5 mg/kg, saline/curcumin 25 mg/kg, Cd/vehicle, Cd/curcumin 12.5 mg/kg, and Cd/curcumin 25 mg/kg. The results of this study revealed that the activities of renal adenosine deaminase and arginase were significantly increased in Cd-treated rats when compared with the control (p < 0.05). However, co-treatment with curcumin inhibits the activities of these enzymes compared with Cd-treated rats. Furthermore, Cd intoxication increased the levels of some renal biomarkers (serum urea, creatinine, and electrolytes) and malondialdehyde level with a concomitant decrease in functional sulfhydryl group and nitric oxide (NO). However, co-treatment with curcumin at 12.5 mg/kg and 25 mg/kg, respectively, increases the nonenzymatic antioxidant status and NO in the kidney, with a concomitant decrease in the levels of malondialdehyde and renal biomarkers. Therefore, our results reinforce the importance of adenosine deaminase and arginase activities in Cd poisoning conditions and suggest some possible mechanisms of action by which curcumin prevent Cd-induced renal toxicity in rats.

Keywords: cadmium; curcumin; l-arginine; renal adenosine; renal biomarkers.

Figure 1

Effect of curcumin on renal adenosine deaminase activity in Cd-induced renal oxidative damage. Data are presented as the mean ± SEM (n = 5). Bars with different letters are significantly (p < 0.05) different from each other. Cd = group receiving vehicle + 2.5 mg/kg cadmium; Cd/Cur 12.5 = group receiving 12.5 mg/kg curcumin + 2.5 mg/kg cadmium; Cd/Cur 25 = group receiving 25 mg/kg curcumin + 2.5 mg/kg cadmium; Control = group receiving saline/vehicle; Cur 12.5 = group receiving 12.5 mg/kg curcumin only; Cur 25 = group receiving 25 mg/kg curcumin only; SEM = standard error of the mean.

Figure 2

Effect of curcumin on renal arginase activity in Cd-induced renal oxidative damage. Data are presented as the mean ± SEM (n = 5). Bars with different letters are significantly different (p < 0.05) from each other. Cd = group receiving vehicle + 2.5 mg/kg cadmium; Cd/Cur 12.5 = group receiving 12.5 mg/kg curcumin + 2.5 mg/kg cadmium; Cd/Cur 25 = group receiving 25 mg/kg curcumin + 2.5 mg/kg cadmium; Control = group receiving saline/vehicle; Cur 12.5 = group receiving 12.5 mg/kg curcumin only; Cur 25 = group receiving 25 mg/kg curcumin only; SEM = standard error of the mean.

Figure 3

Effect of curcumin on renal nitric oxide level in Cd-induced renal oxidative damage. Data are presented as the mean ± SEM (n = 5). Bars with different letters are significantly different (p < 0.05) from each other. Cd = group receiving vehicle + 2.5 mg/kg cadmium; Cd/Cur 12.5 = group receiving 12.5 mg/kg curcumin + 2.5 mg/kg cadmium; Cd/Cur 25 = group receiving 25 mg/kg curcumin + 2.5 mg/kg cadmium; Control = group receiving saline/vehicle; Cur 12.5 = group receiving 12.5 mg/kg curcumin only; Cur 25 = group receiving 25 mg/kg curcumin only; SEM = standard error of the mean.

Figure 4

Effect of curcumin on renal malondialdehyde (MDA) level in Cd-induced renal oxidative damage. Data are presented as the mean ± SEM (n = 5). Bars with different letters are significantly different (p < 0.05) from each other. Cd = group receiving vehicle + 2.5 mg/kg cadmium; Cd/Cur 12.5 = group receiving 12.5 mg/kg curcumin + 2.5 mg/kg cadmium; Cd/Cur 25 = group receiving 25 mg/kg curcumin + 2.5 mg/kg cadmium; Control = group receiving saline/vehicle; Cur 12.5 = group receiving 12.5 mg/kg curcumin only; Cur 25 = group receiving 25 mg/kg curcumin only; SEM = standard error of the mean.

Figure 5

Effect of curcumin on (A) renal total thiol and (B) nonprotein thiol levels in Cd-induced renal oxidative damage. Data are presented as the mean ± SEM (n = 5). Bars with different letters are significantly (p < 0.05) different from each other. Cd = group receiving vehicle + 2.5 mg/kg cadmium; Cd/Cur 12.5 = group receiving 12.5 mg/kg curcumin + 2.5 mg/kg cadmium; Cd/Cur 25 = group receiving 25 mg/kg curcumin + 2.5 mg/kg cadmium; Control = group receiving saline/vehicle; Cur 12.5 = group receiving 12.5 mg/kg curcumin only; Cur 25 = group receiving 25 mg/kg curcumin only; SEM = standard error of the mean.

Figure 6

Effect of curcumin on renal cadmium level in Cd-induced renal oxidative damage. Data are presented as the mean ± SEM (n = 5). Bars with different letters are significantly different (p < 0.05) from each other. Cd = group receiving vehicle + 2.5 mg/kg cadmium; Cd/Cur 12.5 = group receiving 12.5 mg/kg curcumin + 2.5 mg/kg cadmium; Cd/Cur 25 = group receiving 25 mg/kg curcumin + 2.5 mg/kg cadmium; Control = group receiving saline/vehicle; Cur 12.5 = group receiving 12.5 mg/kg curcumin only; Cur 25 = group receiving 25 mg/kg curcumin only; MDA = malondialdehyde; SEM = standard error of the mean.