Effects of Dietary Arachidonic Acid Supplementation on Age-Related Changes in Endothelium-Dependent Vascular Responses

Abstract

SummaryThe purpose of the present study was to examine the effects of dietary supplementation of arachidonic acid (ARA) on age-related changes in endothelium-dependent vascular responses. Young male Fisher-344 rats (2-mo-old) and aged rats of the same strain (22-mo-old) were randomly separated into a control diet group (young control, YC; old control, OC) and an ARA-containing diet group (young ARA, YA; old ARA, OA). After a 2-mo feeding period, vascular responses were evaluated using both endothelium-intact and -denuded aortic rings. Phenylephrine ( ␣ 1 -adrenoceptor agonist)-induced vasoconstrictor responses in endothelium-intact rings from group OC tended to be augmented compared with those of rings from groups YC and YA, although this augmentation was significantly suppressed by dietary supplementation of ARA. There were no significant differences in vascular responses to phenylephrine in endothelium-denuded rings among groups YC, YA, OC, and OA. Acetylcholine (Ach)-induced, endothelium-dependent vasorelaxation was attenuated in groups OC and OA compared with that in groups YC and YA. ARA supplementation induced slight enhancement of Ach-induced vasorelaxation in aged rats. Ach-induced vasorelaxation correlated very well with aortic ARA concentration in aged rats, but not in young rats. There were no significant differences in endothelium-independent vasodilator responses to sodium nitroprusside in endothelium-denuded rings among groups YC, YA, OC, and OA. These findings suggest that dietary ARA supplementation improves the age-related endothelial dysfunction that leads to various cardiovascular diseases. Key Words aging, arachidonic acid, endothelial dysfunction, acetylcholine, phenylephrine Age is a recognized independent risk factor for the development of cardiovascular disease. There is accumulating evidence in both humans and experimental animals that aging is associated with endothelial dysfunction characterized by progressive decline in endothelium-dependent vasorelaxation in resistance and conductance arteries ( 1-3 ). Although the mechanisms underlying this age-related endothelial dysfunction are not fully understood, several factors, including attenuation of nitric oxide (NO)-mediated vasodilation, augmented production of oxygen-derived free radicals, and increased release of cyclooxygenase-derived vasoconstrictor substances, appear to contribute to this vascular change ( 4 ).Arachidonic acid (ARA) is a major constituent of cell membranes, and in this capacity plays important roles in the maintenance of physiological function. Several studies have demonstrated that the amount of ARA in membrane phospholipids in the brain is lower in aged animals than in young animals, and that certain neural deficiencies in aged animals are closely related to this decrease in membrane ARA concentration ( 5, 6 ). It has recently been reported that dietary ARA supplementation to aged rats can alleviate age-related neural dysfunction ( 7 , 8 ).However, little is known concerning the involvement of membrane ARA in age-...

Supplementation of arachidonic acid-enriched oil increases arachidonic acid contents in plasma phospholipids, but does not increase their metabolites and clinical parameters in Japanese healthy elderly individuals: a randomized controlled study

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Intake of arachidonic acid-containing lipids in adult humans: dietary surveys and clinical trials

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Pharmacology in Health Foods: Effects of Arachidonic Acid and Docosahexaenoic Acid on the Age-Related Decline in Brain and Cardiovascular System Function

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