Alleviation of carbon tetrachloride-induced chronic liver injury and related dysfunction by L-tryptophan in rats

We examined whether L-tryptophan (Trp) alleviates carbon tetrachloride (CCl 4)-induced chronic liver injury and related dysfunction. Fifty rats were cl assified into four groups: the first (15 rats) served as the control; the s econd (10 rats) received subcutaneous injections of CCl4 (10 mL/kg) twice w eekly for 8 weeks; the third (15 rats) received daily intraperitoneal injec tions of Trp (50 mg/kg) for 2 weeks after 6 weeks of CCl4 treatment; the fo urth (10 rats) received both treatments. The activities of serum transamina ses and the content of liver total hydroxyproline increased after 6 and 8 w eeks of CCl4 treatment. The concentrations of serum albumin and liver prote in and the in vitro activity of liver protein synthesis fell after 8 weeks of the treatment. Trp administration alleviated all these changes. At 6 and 8 weeks of CCl4 treatment the serum triglyceride concentration fell, where as the liver triglyceride and lipid peroxide concentrations were elevated. Trp administration hardly affected these changes. These results indicate th at Trp alleviates CCl4-induced chronic liver injury possibly by maintaining the activity of protein synthesis.