Effect of dietary docosahexaenoic acid on biosynthesis of docosahexaenoic acid from alpha-linolenic acid in young rats

Abstract

Docosahexaenoic acid (DHA), a crucial nervous system n-3 PUFA, may be obtained in the diet or synthesized in vivo from dietary a-linolenic acid (LNA). We addressed whether DHA synthesis is regulated by the availability of dietary DHA in artificially reared rat pups, during p8 to p28 development. Over 20 days, one group of rat pups was continuously fed deuterium-labeled LNA (d5-LNA) and no other n-3 PUFA (d5-LNA diet), and a second group of rat pups was fed a d5-LNA diet with unlabeled DHA (d5-LNA 1 DHA diet). The rat pups were then euthanized, and the total amount of deuterium-labeled docosahexaenoic acid (d5-DHA) (synthesized DHA) as well as other n-3 fatty acids present in various body tissues, was quantified. In the d5-LNA 1 DHA group, the presence of dietary DHA led to a marked decrease (3-to 5-fold) in the total amount of d5-DHA that accumulated in all tissues that we examined, except in adipose. Overall, DHA accretion from d5-DHA was generally diminished by availability of dietary preformed DHA, inasmuch as this was found to be the predominant source of tissue DHA. When preformed DHA was unavailable, d5-DHA and unlabeled DHA were preferentially accreted in some tissues along with a net loss of unlabeled DHA from other organs.-DeMar, Jr., J. C., C. DiMartino, A. W. Baca, W. Lefkowitz, and N. Salem, Jr. Effect of dietary docosahexaenoic acid on biosynthesis of docosahexaenoic acid from alpha-linolenic acid in young rats. J. Lipid Res. 2008Res. . 49: 1963Res. -1980 Supplementary key words essential fatty acids • lipid metabolism • early development • infant formula composition Docosahexaenoic acid (DHA; 22:6n-3) is an n-3 PUFA that is particularly enriched in the phospholipids of cells constituting the mammalian nervous system (1, 2). Functionally, DHA enhances membrane elasticity and molecular motion and thus promotes signal transduction via enhanced protein/receptor interactions (3-6). DHA is also the activating ligand for multiple transcriptional factors that control the expression of enzymes involved in fatty acid synthesis and b-oxidation (7). DHA may be directly obtained in the diet, as preformed DHA, or synthesized in vivo from other common dietary n-3 PUFAs such as a-linolenic acid (LNA, 18:3n-3), eicosapentaenoic acid (EPA, 20:5n-3), or docosapentaenoic acid (DPA, 22:5n-3) (8). All of these n-3 PUFAs may be converted in vivo to DHA through sequential steps of elongation, desaturation, and peroxisomal b-oxidation (9). Prolonged dietary deprivation of all n-3 PUFAs in rat pups, initiated prior to weaning, depletes up to 80% of their brain DHA (10-12). Such depletion of brain DHA in rodents leads to distinct impairments in brain function (11,(13)(14)(15)(16)(17). Piglets and monkeys also show impaired neural function when deprived of n-3 PUFA for an extended period during infancy (18,19). The essentiality of DHA for human infant nutrition in support of neuronal function has been shown by DHA supplementation, enhancing visual acuity and cognition-related test scores in human infants (20)(21)(2...

Global Estimates of Dietary Intake of Docosahexaenoic Acid and Arachidonic Acid in Developing and Developed Countries

“…Moreover, there is emerging data to confirm that there is global variation in the prevalence of the minor alleles of FADS SNPs and this may contribute to population differences in LCPUFA status and subsequent health outcomes [16]. Although these metabolic and genetic factors may influence the LCPUFA status, and recommendations on dietary intake of n-3 and n-6 LCPUFAs need to be sensitive to their effects, the adequacy of the dietary intake will play the dominant role in determining the LCPUFA status of a population [17]. …”

ELOVL4 protein preferentially elongates 20:5n3 to very long chain PUFAs over 20:4n6 and 22:6n3

“…AA, which is mostly acquired from the diet or synthesized through elongation and desaturation of 18:2n6, is the major n6 LC-PUFA of the neural and vascular tissues of the retina and brain ( 22 ). Over the decades, much has been done showing that these LC-PUFAs are necessary for normal neural development and function (24)(25)(26)(27)(28)(29)(30)(31)(32). They also play signifi cant roles in maintaining cell structure and physiological function by modulating cell differentiation and normal growth through signal transduction and cellular metabolism (33)(34)(35).…”

Alimentos ricos en ácidos grasos v-3 libres de contaminantes y aptos para vegetarianos, y su importancia en el desarrollo neurológico normal

“…Esto es así, igualmente, en otros mamí-feros como monos 36 , ratas 53 y ratones 54 . Consecuentemente, el consumo de v-3, especialmente DHA, garantiza el desarrollo normal y el buen funcionamiento del cerebro, según muestran estudios con ratas 1,2,55 . Ratas con deficiencia cerebral de DHA muestran una reducción en la expresión del factor de crecimiento neuronal (NGF de sus siglas en inglés) 56 , menor tamaño medio de las neuronas 57 , menor ramificación neuronal 58 , y alteraciones ultraestructurales en la morfología sináptica 45 .…”