Prevention of liver cirrhosis in rats by curcumin.

BACKGROUND AND AIM: Curcumin, the major polyphenolic compound in turmeric, has been shown to attenuate hepatic damage in several animal models of liver injury. The aim of the present study was to examine the efficacy of curcumin in preventing thioacetamide-induced cirrhosis and to unravel the mechanism of curcumin's effect on hepatic fibrosis in rats. METHODS: Liver cirrhosis was induced by thioacetamide (TAA; 200 mg/kg, i.p.) twice weekly for 12 weeks. One group of rats concomitantly received curcumin (300 mg/kg/day, by gavage for 12 weeks); the control group received the solvent at identical amounts and duration. RESULTS: TAA administration induced liver cirrhosis, which was inhibited by curcumin. Liver histopathology, hydroxyproline levels and spleen weights were significantly lower in the rats treated with TAA+curcumin compared with TAA only (P<0.001). Immunohistochemical studies and in situ hybridization demonstrated inhibition of hepatic stellate cell (alpha smooth muscle actin-positive) activation and collagen alpha1 (I) gene expression in the livers of the TAA+curcumin-treated rats. Curcumin reduced oxidative stress as shown by the decreased hepatic nitrotyrosine staining in the curcumin+TAA-treated rats. Curcumin treatment had no effect on pre existing liver cirrhosis. As determined by in vitro studies using the rat HSC-T6 cell line, curcumin had no direct inhibitory effect on collagen alpha1 (I) messenger RNA expression. Further studies in these cells using reverse transcriptase-polymerase chain reaction demonstrated that curcumin had no effect on the expression of PDGF-induced TIMP-1 and TIMP-2, TGFbeta1, TGFbeta2 and MCP-1 but significantly inhibited tumor necrosis factor alpha expression. Curcumin had no effect on hepatic stellate cells proliferation. Zymography showed that curcumin had no effect on matrix metalloproteinase-2 activity. CONCLUSIONS: Curcumin inhibited the development of TAA-induced liver cirrhosis mainly due to its anti-inflammatory activities and not by a direct anti-fibrotic effect. As curcumin ingestion is safe in humans, it may be reasonable to assess in clinical studies the beneficial effect of curcumin in slowing the development of liver cirrhosis.

Curcumin ameliorates acute thioacetamide-induced hepatotoxicity.

BACKGROUND AND AIM: Increased production of reactive oxygen species and nitric oxide and activation of nuclear factor kappa B are implicated in the pathogenesis of various liver diseases, including fulminant hepatic failure. Curcumin is a naturally occurring anti-oxidant that reduces oxidative stress and inhibits nuclear factor kappa B and nitric oxide formation. The aim of the present study is to assess curcumin's therapeutic potential in acute thioacetamide hepatotoxicity, a rat model of fulminant hepatic failure. METHODS: Fulminant hepatic failure was induced by two intraperitoneal (i.p.) injections of 300 mg/kg thioacetamide (TAA) at 24-h intervals. The experimental groups received a low-dose (200 mg/kg per day, i.p.) or a high-dose (400 mg/kg per day) of curcumin, initiated 48 h prior to the first TAA injection. A fourth group was administered neither TAA nor curcumin and served as a control. RESULTS: The survival rate was higher in both curcumin-treated groups compared to the TAA only treated group. Biochemical parameters of liver injury, blood ammonia and hepatic necroinflammation were lower in the low-dose curcumin group compared to TAA controls, and were further reduced in the high-dose group (P < 0.05 and P < 0.01, respectively). Curcumin treatment also reduced the TAA-induced elevated hepatic levels of thiobarbituric acid-reactive substances (TBARS), and inhibited the nuclear binding of nuclear factor kappa B (NFkappaB) and inducible nitric oxide (iNOS) protein expression. CONCLUSIONS: Curcumin improved survival and minimized oxidative stress, hepatocellular injury and hepatic necroinflammation, NFkappaB binding and iNOS expression in a rat model of FHF. These findings support the role of ROS, NFkappaB and iNOS in mediating liver insult due to TAA, and that of curcumin as a hepato-protectant.