Curcumin decreased oxidative stress, inhibited NF-kappaB activation, and improved liver pathology in ethanol-induced liver injury in rats

Abstract

To study the mechanism of curcumin-attenuated inflammation and liver pathology in early stage of alcoholic liver disease, female Sprague-Dawley rats were divided into four groups and treated with ethanol or curcumin via an intragastric tube for 4 weeks. A control group treated with distilled water, and an ethanol group was treated with ethanol (7.5 g/kg bw). Treatment groups were fed with ethanol supplemented with curcumin (400 or 1 200 mg/kg bw). The liver histopathology in ethanol group revealed mild-to-moderate steatosis and mild necroinflammation. Hepatic MDA, hepatocyte apoptosis, and NF-kappaB activation increased significantly in ethanol-treated group when compared with control. Curcumin treatments resulted in improving of liver pathology, decreasing the elevation of hepatic MDA, and inhibition of NF-kappaB activation. The 400 mg/kg bw of curcumin treatment revealed only a trend of decreased hepatocyte apoptosis. However, the results of SOD activity, PPARgamma protein expression showed no difference among the groups. In conclusion, curcumin improved liver histopathology in early stage of ethanol-induced liver injury by reduction of oxidative stress and inhibition of NF-kappaB activation.

Figure 1

Hematoxylin-eosin-stained liver sections (x400). (a) Control group showed normal liver histopathology. (b) Ethanol-treated group showed steatosis (small arrows) and infiltration of inflammatory cells (block arrow). (c) and (d) Curcumin treatment (400 or 1,200 mg/kg bw a day) showed examples of improvement in steatosis and inflammation.

Figure 2

Hepatic MDA levels in all groups. All data are expressed as mean ± SD. The hepatic MDA levels were significantly higher in the ethanol-treated group (Ethanol) when compared with control group (^aP < .05). Two doses of curcumin treatment (Ethanol + curI and Ethanol + curII) decreased significantly hepatic MDA levels when compared with Ethanol (^bP < .05).

Figure 3

Hepatic SOD activity in all groups. All data are expressed as mean ± SD. No significant differences were observed among groups.

Figure 4

Number of apoptosis cells in all groups. All data are expressed as mean ± SD. Ethanol-treated group (Ethanol) increased significantly apoptotic cells when compared with control group (^aP < .05).

Figure 5

Representative liver sections processed for apoptosis assay by TUNEL reaction (x400). (a) Control group. (b) Ethanol-treated group, the black arrows indicated a TUNEL-positive apoptoic hepatocyte found frequently around central vein. (c) and (d) curcumin treatment (400 or 1,200 mg/kg bw a day) showed a decrease of apoptotic hepatocytes.

Figure 6

Number of NF-κB p65 positive cells/high-power field in all groups. All data are expressed as mean ± SD. Ethanol-treated group (Ethanol) increased significantly NF-κB p65 positive cells when compared with control group (^aP < .05). Two doses of curcumin treatment (Ethanol + curI and Ethanol + curII) decreased significantly NF-κB p65 positive cells when compared with Ethanol (^bP < .05).

Figure 7

Immunohistochemistry of NF-κB p65 expression in rat liver (x400). (a) Control group. (b) Ethanol-treated group showed NF-κB p65 positive cells in nuclei (black arrow). (c) and (d) curcumin treatment (400 or 1,200 mg/kg bw a day) showed a diminishment of NF-κB expression in hepatocyte nuclei.

Figure 8

PPARγ protein expression determined by Western blot analysis. (a) represented bands of PPARγ and β-actin. (b) normalized densitometric ratio of PPARγ to β-actin.