Abstract
To determine how the level of dietary n-6 PUFA affects the rate of loss of arachidonic acid (ARA) and DHA in brain phospholipids, male rats were fed either a deprived or adequate n-6 PUFA diet for 15 weeks postweaning, and then subjected to an intracerebroventricular infusion of (3)H-ARA or (3)H-DHA. Brains were collected at fixed times over 128 days to determine half-lives and the rates of loss from brain phospholipids (J out). Compared with the adequate n-6 PUFA rats, the deprived n-6-PUFA rats had a 15% lower concentration of ARA and an 18% higher concentration of DHA in their brain total phospholipids. Loss half-lives of ARA in brain total phospholipids and fractions (except phosphatidylserine) were longer in the deprived n-6 PUFA rats, whereas the J out was decreased. In the deprived versus adequate n-6 PUFA rats, the J out of DHA was higher. In conclusion, chronic n-6 PUFA deprivation decreases the rate of loss of ARA and increases the rate of loss of DHA in brain phospholipids. Thus, a low n-6 PUFA diet can be used to target brain ARA and DHA metabolism.
Highlights
To determine how the level of dietary n-6 PUFA affects the rate of loss of arachidonic acid (ARA) and DHA in brain phospholipids, male rats were fed either a deprived or adequate n-6 PUFA diet for 15 weeks postweaning, and subjected to an intracerebroventricular infusion of 3HARA or 3H docosahexaenoic acid (3H-DHA)
Alterations in brain DHA concentration and metabolism appear to occur below a threshold of 0.8% ALA in the diet, Abbreviations: ALA, ␣-linolenic acid; ARA, arachidonic acid; ChoGpl, choline glycerophospholipid; COX, cyclooxygenase; cPLA2, cytosolic phospholipase A2; DPA, docosapentaenoic acid; EtnGpl, ethanolamine glycerophospholipid; FAME, fatty acid methyl esters; GCFID, gas chromatography with flame-ionization detection; 3H-ARA, 5,6,8,9,11,12,14,15-3H arachidonic acid; 3H-DHA, 4,7,10,13,16,19-3H docosahexaenoic acid; iPLA2, calcium-independent phospholipase A2; LA, linoleic acid; LSC, liquid scintillation counting; PtdIns, phosphatidylinositol; PtdSer, phosphatidylserine
Rats fed an n-6 PUFA-deprived diet (2% LA) or an n-6 PUFA-adequate diet (24% LA) for 15 weeks were infused with 3H-ARA or 3H-DHA, which allowed for the determination of the rate of loss of ARA and DHA
Summary
To determine how the level of dietary n-6 PUFA affects the rate of loss of arachidonic acid (ARA) and DHA in brain phospholipids, male rats were fed either a deprived or adequate n-6 PUFA diet for 15 weeks postweaning, and subjected to an intracerebroventricular infusion of 3HARA or 3H-DHA. Feeding rats an n-3 PUFAdeprived diet that contains ALA at a concentration of 0.04% versus an n-3 PUFA-adequate diet containing ALA at 4.4% of all fatty acids decreased the concentration of DHA by 37% and increased docosapentaenoic acid (DPA) n-6 concentration by 95% in brain total phospholipids, but did not change the concentration of ARA [10]. Alterations in brain DHA concentration and metabolism appear to occur below a threshold of 0.8% ALA in the diet, Abbreviations: ALA, ␣-linolenic acid; ARA, arachidonic acid; ChoGpl, choline glycerophospholipid; COX, cyclooxygenase; cPLA2, cytosolic phospholipase A2; DPA, docosapentaenoic acid; EtnGpl, ethanolamine glycerophospholipid; FAME, fatty acid methyl esters; GCFID, gas chromatography with flame-ionization detection; 3H-ARA, 5,6,8,9,11,12,14,15-3H arachidonic acid; 3H-DHA, 4,7,10,13,16,19-3H docosahexaenoic acid; iPLA2, calcium-independent phospholipase A2; LA, linoleic acid; LSC, liquid scintillation counting; PtdIns, phosphatidylinositol; PtdSer, phosphatidylserine
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