EFFECTS OF ALPHA-LINOLENIC ACID DEFICIENCY AND AGE ON OXIDATIVE-PHOSPHORYLATION AND FATTY-ACID COMPOSITION OF RAT-LIVER MITOCHONDRIA

Two weeks before mating, female rats from n-3 PUFA deficient lineage were divided into two groups; the first group continued to get the n-3 PUFA deficient diet (peanut oil) and the second one received a control diet (peanut and rapeseed oil mixture). Total phospholipid fatty acid composition, respiration, and succinic dehydrogenase (SDH) activity were studied in liver mitochondria from 14-, 30-, and 90-day-old male rats delivered by these two experimental groups. Moreover, the principal phospholipid classes (PC, PE, CL) content and F1F0 ATPase activity were studied in liver submitochondrial (inner) membrane from 30-day-old rats. The results showed that dietary n-3 PUFA deficiency did not modify cholesterol and phospholipid levels in total mitochondrial lipids whatever the animal age. However, 22:6 n-3 (DHA) level in phospholipids was considerably reduced by this deficiency; this reduction was compensated by an increase in 22:5 n-6 and 20:4 n-6 so that the total polyunsaturated fatty acid sum (n-6 + n-3) was not modified. It did not alter basal and stimulated succinic dehydrogenase specific activity, state 3, state 4, neither respiratory control ratio. However, the rate of oxidative phosphorylation pathway was doubled between 14- and 30-day-old animals independently of diet. The relative proportions of the major phospholipid classes in submitochondrial membrane were not altered. Also, there was no significant effect on F1F0 ATPase activity in submitochondrial membrane. Finally, the considerable reduction of DHA level and the parallel increase of the n-6/n-3 ratio in mitochondrial membrane phospholipids did not influence mitochondrial physiological activity, at least with regard to experimental conditions used and to the parameters studied.