Peroxisomal Proliferation in Rat Liver and Essential Fatty Acid Deficiency

Abstract

SummaryThe effects of essential fatty acid (EFA) deficiency were studied on male Wistar rats membrane lipid composition, enzyme activities and proliferation of liver peroxisome by feeding the animals, during 4 weeks, with fat free diets supplemented or not with a peroxisome proliferator, clofibrate (CLO).In deficient (E) goup, peroxisomal membrane was characterized by higher level of total de nova synthesized unsaturated (n-9 and n-7 series) fatty acids and lower content of EFA (n-6 and n-3 series) and exhibited cholesterol (CHOL) to phospholipids (PLs) ratio diminution compared with that of control (C) group. Co-administration of CLO with the fat-free diet (EC group) enhanced the membrane uptake of n-9 fatty acids. Slight increase of membrane dihydroxyacetone-phosphate acyl-transferase (DHAP-AT) and decrease of palmitoyl-CoA synthetase activities were found in E group which featured normal-shaped peroxisomes.In EC group, enzyme inductions of peroxisomal pamitoyl-CoA oxidase and palmitoyl-CoA synthetase were slightly higher and significantly lower respectively compared with those of C group treated with CLO (CC group) whereas activity of DHAP-AT was stable. Identical marked proliferation of peroxisomes were observed in both groups.It is inferred that, despite the parallel alterations of membrane lipid composition and of enzyme activities of peroxisomes upon 4 weeks of EFA deficient-diet, the biogenesis and proliferation of the organelles were independently processed at a normal level. The possibility of homeostatic regulation and its physiological importance were discussed.