Accumulation of diacylglycerol in the liver membrane of the Long-Evans Cinnamon (LEC) rat with hepatitis: FT-IR spectroscopic and HPLC detection

Long-Evans Cinnamon (LEC) rats develop severe hepatitis and subsequent hepa toma with excess accumulation of copper in the liver with increasing age. L ipids extracted from the LEC rat liver membrane were studied using FT-IR sp ectroscopy and an HPLC technique at the stages of pre-hepatitis and hepatit is, i.e. at 10 and 16 weeks of age, respectively. The 10-week-old rats exhi bited an IR spectrum characteristic of a phosphatidylcholine and phosphatid ylethanolamine mixture with a ratio of 2:1. The 16-week-old rats developed new absorption bands at 1161 and 1070 cm(-1), which were assigned to the sp ectra of triglyceride, neutral Lipid, and diacylglycerol, an endogenous act ivator of protein kinase C, respectively. The diacylglycerol was estimated to amount to ca. 10% (w/w) of phospholipid extract by comparing the spectru m with those of model compounds. This was confirmed using an HPLC assay. Pr eviously, we found that a serum response factor is activated by copper in t he LEC rat liver, and suggested that it must mediate proto-oncogene c-fos i nduction. The results obtained here suggest that accumulation of diacylglyc erol plays an important role in development of hepatoma in LEC rats by medi ating proto-oncogene c-fos induction. (C) 2000 Elsevier Science Ireland Ltd . All rights reserved.