ABSTRACT
The effect of long term feeding of cholesterol 100 mg/kg/day for 20 weeks on free amino acid patterns in plasma and liver contents in rats was investigated using LKB-amino acid analyzer [Biochrom Ltd., Cambridge, England] and correlated these results with their effects on plasma levels of cholesterol, triglyceride, lipoprotein and Gamma Glutamyl Transferase [yGT]. indicate that all amino acid contents in the liver were significantly decreased in the cholesterol feed animal group. The amplitude of reductions varied between 40-100%. Glutamine and tryptophan were not detected in the liver of cholesterol feed group. The plasma concentrations of taurine, glutamate, alanine, valine and phenylalanine were elevated whose mean percentage increases were 48 +/- 4, 40 +/- 3, 25 +/- 3 and 35 +/- 4 respectively. These increases were associated with significant decrease in the concentration of ornithine [37%]. Meanwhile proline was not detected in the plasma of treated animals. Also, plasma cholesterol, triglyceride, lipoproteins and yGT were determined by colorimetric methods using Kits from Boehringer Mannheim [GmbH]. Results indicated that feeding cholesterol significantly increased the plasma yGT activity. In these experimental conditions the chronic intake of cholesterol had no significant effects on plasma cholesterol or other plasma lipids parameters tested except plasma triglyceride which was significantly increased, these results indicated that there are interactions between cholesterol intake and hepatic glutamine and tryptophan as well as plasma proline and these interaction mechanisms may be considered the factor generating metabolic events, which play physiological functions in the regulation of plasma cholesterol. Thus, under pathological conditions there is an imbalance between these interaction mechanisms which cause an increase in the circulating levels of cholesterol, leading to pathological processes such as hyperlipidemias, atherosclerosis and bile stones