Vegetable oils rich in alpha linolenic acid increment hepatic n-3 LCPUFA, modulating the fatty acid metabolism and antioxidant response in rats.

Key Findings

The present study assessed the effect of feeding rats with oils having high levels of ALA on the hepatic and epididymal n-3 LCPUFA metabolism (fatty acid accretion, activity and expression of key enzymes and transcription factors) along with changes in the oxidative status and the antioxidant response. Vegetable oils having different content of LA and increasing high content of ALA produced the following results (i) increasing the accretion of ALA and its transformation to EPA and DHA; (ii) reducing the desaturation activity and expression of Δ-5 and Δ-6 desaturases as a regulatory action due to the tissue increasing of n-3 LCPUFA, (iii) increasing the expression and DNA-binding activity of the transcription factor PPAR-α ; (iv) decreasing the expression and DNA-binding activity of the transcription factor SREBP-1c; (v) inhibiting the activity of hepatic lipogenic enzymes ACC, FAS and increasing the activity of the fat pro-oxidizing enzyme CPT-I; (vi) decreasing the activity of epididymal lipogenic enzymes ACC, G-6-PDH and MA; and (vii) increasing the hepatic antioxidant status (high GSH and GSH/GSSG ratio and the activity of antioxidant enzymes SOD, CAT, GPX y GR). Diets with high ALA content improve tissue n-3 LCPUFA content, the antioxidant status, the capacity of fat oxidation and reduce the activity of fat synthesis.

ABSTRACT

Alpha-linolenic acid (C18:3 n-3, ALA) is an essential fatty acid and the metabolic precursor of long-chain polyunsaturated fatty acids (LCPUFA) from the n-3 family with relevant physiological and metabolic roles: eicosapentaenoic acid (C20:5 n-3, EPA) and docosahexaenoic acid (C22:6 n-3, DHA). Western diet lacks of suitable intake of n-3 LCPUFA and there are recommendations to increase the dietary supply of such nutrients. Seed oils rich in ALA such as those from rosa mosqueta (Rosa rubiginosa), sacha inchi (Plukenetia volubis) and chia (Salvia hispanica) may constitute an alternative that merits research. This study evaluated hepatic and epididymal accretion and biosynthesis of n-3 LCPUFA, the activity and expression of Δ-5 and Δ-6 desaturase enzymes, the expression and DNA-binding activity of PPAR-α and SREBP-1c, oxidative stress parameters and the activity of antioxidative enzymes in rats fed sunflower oil (SFO, 1% ALA) as control group, canola oil (CO, 10% ALA), rosa mosqueta oil (RMO, 33% ALA), sacha inchi oil (SIO, 49% ALA) and chia oil (ChO, 64% ALA) as single lipid source. A larger supply of ALA increased the accretion of n-3 LCPUFA, the activity and expression of desaturases, the antioxidative status, the expression and DNA-binding of PPAR-α, the oxidation of fatty acids and the activity of antioxidant enzymes, whereas the expression and DNA-binding activity of SREBP-1c transcription factor and the biosynthetic activity of fatty acids declined. Results showed that oils rich in ALA such as SIO and ChO may trigger metabolic responses in rats such as those produced by n-3 PUFA.