Effect of celecoxib, a selective cyclooxygenase-2 inhibitor on carbon tetrachloride intoxication in rats.

CCl(4) (0.5 ml/kg as CCl(4)) was orally administered to rats. Twelve hours after administration of CCl(4), plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, indicators of liver necrosis, were significantly higher than those in the control group showing that active liver necrosis took place. At the same time the level of liver vitamin C was decreased significantly compared to that in the control group. Oral administration of 100 mg/kg each of celecoxib 3 and 8 h after CCl(4) treatment did not change plasma ALT and AST and liver vitamin C levels 12 h after CCl(4) treatment, but 24 h after CCl(4) treatment, significantly decreased plasma ALT and AST levels and elevated liver vitamin C level. These finding suggested that celecoxib effectively ameliorated the necrotic action and the oxidative stress induced by CCl(4) in the second phase. Although the plasma levels of all ceramide species were significantly increased 24 h after CCl(4) intoxication, treatment with celecoxib significantly reduced the total ceramide concentration in plasma. These results indicated that celecoxib significantly ameliorated the toxicity of CCl(4) in the second phase.

Neutral sphingomyelinase-induced ceramide accumulation by oxidative stress during carbon tetrachloride intoxication.

Ceramide is a biologically active lipid causing apoptosis in a variety of cells. In this study, we examined the effect of CCl4 on the ceramide metabolism and indicators of oxidative stress. After 12 h of oral administration of CCl4 (4 ml/kg body weight as a 1:1 mixture of CCl4 and mineral oil) to rats, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were increased. Antioxidants such as vitamins C and E were decreased in the liver and kidney. In addition, the ratio of GSH/GSSG in the liver, plasma, kidney, and brain decreased at 2h. The total ceramide in the liver significantly increased as early as 2h after CCl4 administration. After 24 and 36 h, the total ceramide in plasma and the kidney was also augmented. In the brain, the total ceramide dramatically increased at 36 h. These results suggested that the increased ceramide in plasma was transferred to the kidney and the brain. The activity of neutral sphingomyelinase (SMase), which was reported to be enhanced by the decrease of GSH, was significantly increased after CCl4 treatment in the liver, kidney, and brain. However, acid SMase activities were not increased in the liver and kidney. Thus, the activation of neutral SMase via oxidative stress induced the increase of ceramide during CCl4 intoxication in not only the liver but also other tissues. These results suggested that the excess accumulation of ceramide causes damage in other organs including the kidney and brain during fulminant hepatic failure.