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Abstract The present study assessed the effect of oral supplementation with docosapentaenoic acid (DPA, 22:5n-3) on the levels of serum and tissue lipid classes and their fatty acid compositions including individual phospholipid types in rat liver, heart, and kidney. Sprague-Dawley rats received daily oral gavage over 10 days as corn oil without (controls) or with purified DPA in free fatty acid form (21.2 mg/day). The DPA group exhibited significantly lower serum lipid concentrations. The concentrations in µmol/100 g serum or lmol/g tissue of DPA in the total lipid (TL) were higher by 2.3-, 2.4-, 10.9-, and 5.1-fold in the DPA group of serum, liver, heart, and kidney, respectively, with the phospholipids (PL) being the major DPA reservoir (45.2-52.1%of the DPA in the TL). No significant differences in DHA (22:6n-3) amounts in TL appeared. The highest relative mol% values as DPA were in heart tissue (means of 11.1% in PL and 16.2% in phosphatidylinositol) and lowest in kidney. The EPA (20:5n-3) concentrations were markedly higher in the DPA group and most pronounced in the kidney (5.1 times higher in the TL as compared to controls) relative to liver and heart yielding an estimated apparent % conversion of DPA to EPA of 67% and EPA:DPA ratios reaching 5.74 in kidney phosphatidylethanolamine. The serum lipid-lowering potential of dietary DPA and its impact in the kidney with the derived EPA warrants investigation.
Keywords Docosapentaenoic acid (DPA 22:5n-3) * Rat serum * Cholesteryl esters * Triacylglycerol(s) * Liver * Heart * Kidney * Apparent retroconversion * Eicosapentaenoic acid (EPA 20:5n-3) * Individual phospholipids
Abbreviations
ARA Arachidonic acid 20:4n-6
ACAT Acyl-CoA:cholesterol acyltransferase
CE Cholesteryl esters
CerPCho Sphingomyelin
DHA Docosahexaenoic acid 22:6n-3
DPA Docosapentaenoic acid 22:5n-3
EPA Eicosapentaenoic acid 20:5n-3
LCAT Lecithin:cholesterol acyltransferase
NEFA Non-esterified fatty acids
PL Phospholipid(s)
PtdCho Phosphatidylcholine
PtdEtn Phosphatidylethanolamine
PtdIns Phosphatidylinositol
PtdSer Phosphatidylserine
PUFA Polyunsaturated fatty acid
TAG Triacylglycerol(s)
TC Total cholesterol
TL Total lipid(s)
TLC Thin-layer chromatography
Introduction
Docosapentaenoic acid (DPA, 22:5n-3) as present in seal meat, whale meat/blubber, plus some fish/fish oils to a lesser extent is a significant component of the long-chain omega-3 fatty acids found in the Inuit diet [1]. While eicosapentaenoic acid (EPA, 20:5n-3) plus docosahexaenoic acid (DHA, 22:6n-3) are credited for the apparent cardioprotective effects of diets rich in marine fats...