Abstract
ObjectivesLutein, a carotenoid with anti-oxidant functions, preferentially accumulates in primate brain and is positively related to cognition in humans. Docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid (PUFA), is also beneficial for cognition, but is susceptible to oxidation. The present study characterized the membrane distribution of lutein in brain regions important for different domains of cognitive function and determined whether membrane lutein was associated with brain PUFA oxidation.MethodsAdult rhesus monkeys were fed a stock diet (~2 mg/day lutein or ~0.5 μmol/kg body weight/day) (n = 9) or the stock diet plus a daily supplement of lutein (~4.5 mg/day or~1 μmol/kg body weight/day) and zeaxanthin (~0.5 mg/day or 0.1 μmol/kg body weight/day) for 6–12 months (n = 4). Nuclear, myelin, mitochondrial, and neuronal plasma membranes were isolated using a Ficoll density gradient from prefrontal cortex (PFC), cerebellum (CER), striatum (ST), and hippocampus (HC). Carotenoids, PUFAs, and PUFA oxidation products were measured using HPLC, GC, and LC-GC/MS, respectively.ResultsAll-trans-lutein (ng/mg protein) was detected in all regions and membranes and was highly variable among monkeys. Lutein/zeaxanthin supplementation significantly increased total concentrations of lutein in serum, PFC and CER, as well as lutein in mitochondrial membranes and total DHA concentrations in PFC only (P<0.05). In PFC and ST, mitochondrial lutein was inversely related to DHA oxidation products, but not those from arachidonic acid (P <0.05).DiscussionThis study provides novel data on subcellular lutein accumulation and its relationship to DHA oxidation in primate brain. These findings support the hypothesis that lutein may be associated with antioxidant functions in the brain.
Highlights
Lutein, a dietary carotenoid found in spinach, kale, eggs, and corn [1], is known to selectively accumulate in the retina of primates where, along with its isomer, zeaxanthin, it forms macular pigment (MP) [2]
In prefrontal cortex (PFC) and ST, mitochondrial lutein was inversely related to Docosahexaenoic acid (DHA) oxidation products, but not those from arachidonic acid (P
This study provides novel data on subcellular lutein accumulation and its relationship to DHA oxidation in primate brain
Summary
A dietary carotenoid found in spinach, kale, eggs, and corn [1], is known to selectively accumulate in the retina of primates where, along with its isomer, zeaxanthin, it forms macular pigment (MP) [2]. Lutein and zeaxanthin serve as antioxidants to protect polyunsaturated fatty acids (PUFAs) in retinal photoreceptors from oxidation [3,4]. MP density is positively correlated to brain lutein concentrations in matched retina and brain tissue of humans and non-human primates [5,6]. Studies in both infants and adults have shown that, despite not being the predominant carotenoid in the diet, concentrations of lutein in the human brain are higher than those of other carotenoids [7,8]. Preferential accumulation of lutein in the brain during multiple life stages may be indicative of an important function
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