The Modulatory Effect of N-Acetyl Cysteine Supplementation on Hepatic Glutathione Concentration and Lipid Peroxidation Status in Old Rats Fed a Low-Protein Diet

Abstract

There is growing evidence in the literature linking oxidant molecules and the degenerative and physiological changes that occur with advancing age. It is now well documented that oxidant molecules cause cell injury and have been shown to be a common factor in many of the age-associated diseases. On the other hand, the body has many antioxidant compounds that minimize oxidant molecules toxic effects. However, with advanced age, oxidant molecule production may overwhelm the antioxidant defenses, thus contributing to many degenerative diseases of aging. Aging is also a risk factor for protein-energy malnutrition; which was shown to be common among elderly populations. Insufficient intake of protein is frequently found in elderly populations. Glutathione (GSH) is one of the major antioxidant compounds in tissue. The presence of GSH in adequate amount may help in reducing the development of aging process and lead to healthy life. One of the most effective compounds used to serve as a cysteine delivery agent is N-acetyle-cysteine (NAC). The aim of the study is to investigate the effect of NAC and dietary protein on hepatic GSH and lipid peroxidation status in old rats. Rats fed a normal-protein (NP) diet, a low-protein (LP) diet, or a low-protein diet supplemented with the NAC (LP+NAC). GSH concentration in liver, serum albumin concentration and thiobarbituric acid reactive substances (TBARS), as an indication of oxidative tissue damage, were measured. Furthermore, a liver sample of each group was histologically examined using electron microscope. There was an increase in the weight gain of rats fed the LP+NAC diet compared to the rats fed the LP diet, despite the similarity of the daily food intake. Dietary supplementation of NAC to the LP diet restored GSH concentration in the liver to that level seen in rats fed the NP diet. The increase in hepatic GSH concentration in the LP+NAC group was parallel to the decrease in the plasma TBARS level. Furthermore, albumin level was increased in animals fed the LP+NAC diet. The study shows the effectiveness of NAC in restoring hepatic GSH concentration and in reducing plasma TBARS concentration in old rats fed low-protein diet.