title: Sex differences in n-3 and n-6 fatty acid metabolism in EFA-depleted rats.
abstract: We studied the effect of sex on the distribution of long-chain n-3 and n-6 fatty acids in essential fatty acid-deficient rats fed gamma-linolenate (GLA) concentrate and/or eicosapentaenoate and docosahexaenoate-rich fish oil (FO). Male and female weanling rats were rendered essential fatty acid deficient by maintaining them on a fat-free semisynthetic diet for 8 weeks. Thereafter, animals of each sex were separated into three groups (n = 6) and given, for 2 consecutive days by gastric intubation, 4 g/kg body wt per day of GLA concentrate (containing 84% 18:2n-6), n-3 fatty acid-rich FO (containing 18% 20:5n-3 and 52% 22:6n-3), or an equal mixture of the two oil preparations (GLA + FO). The fatty acid distributions in plasma and liver lipids were then examined. GLA treatment increased the levels of C-20 and C-22 n-6 fatty acids in all lipid fractions indicating that GLA was rapidly metabolized. However, the increases in 20:3n-6 were less in females than those in males, while those in 20:4n-6 were greater, suggesting that the conversion of 20:3n-6 to 20:4n-6 was more active in female than in male rats. FO treatment increased the levels of 20:5n-3 and 22:6n-3 and reduced those of 20:4n-6. The increase in n-3 fatty acids was greater in females than that in males and the reduction in 20:4n-6 was smaller. Consequently, the sum of total long-chain EFAs incorporated was greater in females than that in males. The administration of n-3 fatty acids also reduced the ratio of 20:4n-6 to 20:3n-6 in GLA + FO-treated rats indicating that n-3 fatty acids inhibited the activity of delta-5-desaturase. However, this effect was not affected by the sex difference.
mesh_terms: D000818:Animals; D001835:Body Weight; D005227:Fatty Acids / Q000097:blood / Q000378:metabolism*; D005228:Fatty Acids, Essential / Q000172:deficiency*; D005260:Female; D005395:Fish Oils / Q000494:pharmacology; D008042:Linolenic Acids / Q000494:pharmacology; D050356:Lipid Metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012727:Sex Characteristics; D017965:gamma-Linolenic Acid
chemical_list: D005227:Fatty Acids; D005228:Fatty Acids, Essential; D005395:Fish Oils; D008042:Linolenic Acids; D017965:gamma-Linolenic Acid