DIETARY POLYUNSATURATED FATTY-ACIDS AND AGING MODULATE GLUTATHIONE-RELATED ANTIOXIDANTS IN RAT-LIVER

The effects of dietary polyunsaturated fatty acids (PUFA) on the age-d ependent changes in liver glutathione antioxidant system were investig ated in male Wistar rats fed diets supplying either balanced amounts o f linoleic and alpha-linolenic acids (control) or deficient in alpha-l inolenic acid [(n-3) deficient]. The animals were studied at the age o f 6 or 24 mo. Glutathione antioxidative metabolism was markedly affect ed by aging. Cytosolic concentration of reduced glutathione (GSH) was lower (P < 0.01), whereas that of oxidized glutathione (GSSG) as well as the GSSG:GSH ratio were greater (P < 0.001) in the 24-mo-old as com pared with the 6-mo-old rats, regardless of the diet. Glutathione pero xidase activities were lower (P < 0.001) in 24-mo-old rats, though mor e markedly in those fed the control diet. The lipid composition of rat liver microsomal membranes was strongly modified by both diet and agi ng. The age-related changes mainly involved the polyunsaturated fatty acids. These results suggest that the nature of dietary PUFA and not o nly their degree of unsaturation affects the cellular glutathione-depe ndent antioxidant system and thus may modify the age-related changes i n metabolic reactions.