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  • Aging decreases docosahexaenoic acid transport across the blood-brain barrier in C57BL/6J mice.

Aging decreases docosahexaenoic acid transport across the blood-brain barrier in C57BL/6J mice.

PloS one (2023-02-17)
Takuro Iwao, Fuyuko Takata, Junichi Matsumoto, Hisataka Aridome, Miho Yasunaga, Miki Yokoya, Yasufumi Kataoka, Shinya Dohgu
ABSTRACT

Nutrients are actively taken up by the brain via various transporters at the blood-brain barrier (BBB). A lack of specific nutrients in the aged brain, including decreased levels of docosahexaenoic acid (DHA), is associated with memory and cognitive dysfunction. To compensate for decreased brain DHA, orally supplied DHA must be transported from the circulating blood to the brain across the BBB through transport carriers, including major facilitator superfamily domain-containing protein 2a (MFSD2A) and fatty acid-binding protein 5 (FABP5) that transport esterified and non-esterified DHA, respectively. Although it is known that the integrity of the BBB is altered during aging, the impact of aging on DHA transport across the BBB has not been fully elucidated. We used 2-, 8-, 12-, and 24-month-old male C57BL/6 mice to evaluate brain uptake of [14C]DHA, as the non-esterified form, using an in situ transcardiac brain perfusion technique. Primary culture of rat brain endothelial cells (RBECs) was used to evaluate the effect of siRNA-mediated MFSD2A knockdown on cellular uptake of [14C]DHA. We observed that the 12- and 24-month-old mice exhibited significant reductions in brain uptake of [14C]DHA and decreased MFSD2A protein expression in the brain microvasculature compared with that of the 2-month-old mice; nevertheless, FABP5 protein expression was up-regulated with age. Brain uptake of [14C]DHA was inhibited by excess unlabeled DHA in 2-month-old mice. Transfection of MFSD2A siRNA into RBECs decreased the MFSD2A protein expression levels by 30% and reduced cellular uptake of [14C]DHA by 20%. These results suggest that MFSD2A is involved in non-esterified DHA transport at the BBB. Therefore, the decreased DHA transport across the BBB that occurs with aging could be due to age-related down-regulation of MFSD2A rather than FABP5.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Phosphatase Inhibitor Cocktail 3, DMSO solution
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Anti-MFSD2A antibody produced in rabbit, affinity isolated antibody, buffered aqueous solution
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Sodium orthovanadate, ≥90% (titration)
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Phenylmethanesulfonyl fluoride, ≥98.5% (GC)
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Protease Inhibitor Cocktail powder, for general use, lyophilized powder
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Phosphatase Inhibitor Cocktail 2, aqueous solution (dark coloration may develop upon storage, which does not affect the activity)
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HEPES, BioPerformance Certified, ≥99.5% (titration), suitable for cell culture
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Hydrocortisone, γ-irradiated, powder, BioXtra, suitable for cell culture
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Anti-FABP5 antibody produced in rabbit, purified immunoglobulin, buffered aqueous solution
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Anti-β-Actin antibody, Mouse monoclonal, clone AC-15, purified from hybridoma cell culture