Effects of 1-O-hexyl-2,3,5-trimethylhydroquinone on carbon tetrachloride-induced hepatic cirrhosis in rats

Aim: The present study was undertaken to evaluate the effects of 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ), a synthesized vitamin E derivative, on carbon tetrachloride (CCl₄)-induced cirrhosis. Methods: Rats were treated with hypodermic injections of CCl₄ twice a week to induce the hepatic cirrhosis, and given drinking water containing HTHQ or solvent. Primary cultures of rat hepatocytes were performed to evaluate the effects of HTHQ on the expression of inducible nitric oxide synthase (iNOS). Results: Masson's staining of rat livers showed fibrosis around pseudo-lobules in the CCl₄ group, the lesions being reduced in the CCl₄ HTHQ group. Increases in liver tissue hydroxyproline and α₁(I) collagen, α-smooth muscle actin and iNOS induced by CCl₄, were also markedly diminished by HTHQ. Furthermore, both HTHQ and vitamin E attenuated interleukin-1β-induced iNOS protein expression in cultured hepatocytes, the potency of HTHQ being 10-times higher than that of vitamin E. Conclusion: HTHQ may inhibit development of hepatic cirrhosis in rats, more potently than vitamin E, by inhibiting the iNOS expression in hepatocytes. Because vitamin E has a radical scavenging action, roles of NO and peroxynitrite will be discussed in the effects of HTHQ on the fibrosis.