Polyunsaturated fatty acid levels in rat tissues after chronic treatment with dietetic oils

The essential fatty acids can be helpful in the prevention of several pathologies. The purpose of this study was to quantify the major n-3 and n-6 fatty acids in tissues of rats fed with flaxseed oil and with a dietetic oil in order to evaluate how their chronic supplementation could influence the correspondent in vivo levels and to study the effectiveness of the dietetic oil compared to flaxseed oil. Fatty acids were successfully extracted from biological samples, subjected to derivatization procedure and analysed by high-performance liquid chromatography with UV detection under gradient elution mode. The developed method showed good linearity, precision and accuracy, with recoveries ranging from 89% to 92%. Animals treated with flaxseed and dietetic oils showed enhanced levels of n-3 fatty acids compared to control groups, with significantly higher levels of eicosapentaenoic acid and docosahexaenoic acid in the brain and in the adipose tissue of the dietetic group compared to the flaxseed group. The obtained data underline that the tested oils can effectively enhance the tissue levels of n-3 fatty acids and therefore they could be successfully used in the dietetic treatment of lipid-related diseases.  (Authors abstract)

The aim of the present work was to study the PUFA tissue levels after a chronic supplementation with flaxseed oil compared to treatment with a dietetic oil containing flaxseed, fish and sunflower oils. The investiagators wanted to verify whether the plasma levels of n-3 PUFAs lead to their in vivo incorporation into different biological tissues (liver, brain and adipose tissue). In this research, the investigators optimized an analytical procedure for the quantification of the principal fatty acids of n-3 and n-6 series in rat tissues: α-linolenic acid (C18:3; ALA), eicosapentaenoic acid (C20:5; EPA), docosapentaenoic acid (C22:5; DPA),  docosahexaenoic acid( C22:6;DHA), linoleic acid (C18:2;LA) and arachidonic acid (C20:4; AA). PUFAs were extracted from the biological samples and subjected to derivatization in the presence of p-bromophenacyl bromide to form highly chromophoric derivatives which are suitable for reversed-phase HPLC/UV (RP-HPLC/UV) quantitative analyses. Satisfactory separations were achieved with a mobile phase of acetonitrile/water under gradient conditions; reliable quantitative results were obtained by using an internal standard to compensate for experimental errors. The analytical procedure was validated on spiked samples and then applied to tissues of rats treated with flaxseed oil and dietetic oil in order to determine the effects of these treatments on the correspondent tissue levels of n-3 and n-6 fatty acids.The method was applied to tissue samples obtained from rats  and the correspondent fatty acids levels were found in liver, brain and adipose tissue. ALA levels were found to be increased in all the analysed tissues, with no significant differences between the flaxseed group and the dietetic group. EPA content increased in all tissues after both treatments, with significantly higher levels in the dietetic oil group.  DPA levels were found to be increased in all the analysed tissues, with a slightly higher increase for the dietetic group in the brain. DHA levels were found to be increased in brain and adipose tissue after both treatments, with significantly higher levels in the dietetic oil group. It has been well documented that the fatty acid composition of adipose tissue in a healthy individual is related to the fatty acid composition of dietary lipids. It is very difficult, but not impossible, to alter the fatty acid profile of the brain cell membranes by dietary supplement, as occurred in this study. (Editors comments)