Abstract
The loss of docosahexaenoic acid (DHA) from the retina or brain has been associated with a loss in nervous-system function in experimental animals, as well as in human infants fed vegetable oil-based formulas. The reversibility of the loss of DHA and the compensation by an increase in the n-6 docosapentaenoic acid (DPAn-6) was studied in young adult rats. Long-Evans rats were subjected to a very low level of n-3 fatty acids through two generations. The F2 generation, n-3-deficient animals at 7 weeks of age were provided a repletion diet containing both α-linolenate and DHA. A separate group of F2 generation rats had been maintained on an n-3-adequate diet of the same composition. Tissues from the brain, retina, liver, and serum were collected on weeks 0, 1, 2, 4, and 8 from both groups of animals. The concentrations of DHA, DPAn-6, and other fatty acids were determined and the rate of recovery and length of time needed to complete DHA recovery were determined for each tissue. The DHA level in the brain at 1 and 2 weeks after diet reversal was only partially recovered, rising to approximately 20% and 35%, respectively, of the n-3-adequate group level. Full recovery was not obtained until 8 weeks after initiation of the repletion diet. Although the initial rate of retinal DHA accretion was greater than that of brain DHA, the half-time for DHA recovery was only marginally greater. On the other hand, the levels of DHA in the serum and liver were approximately 90% and 100% replaced, respectively, within 2 weeks of diet reversal. A consideration of the total amounts and time courses of DHA repleted in the nervous system compared with the liver and circulation suggests that transport-related processes may limit the rate of DHA repletion in the retina and brain. —Moriguchi, T., J. Loewke, M. Garrison, J. N. Catalan, N. Salem, Jr. Reversal of docosahexaenoic acid deficiency in the rat brain, retina, liver, and serum.
Highlights
The loss of docosahexaenoic acid (DHA) from the retina or brain has been associated with a loss in nervoussystem function in experimental animals, as well as in human infants fed vegetable oil-based formulas
This study investigates the time course of reversal of fatty acid compositional differences induced by an n-3-Def diet over two generations
The n-3-Def diet was very effective in inducing n-3 fatty acid deficiency in the nervous system (Table 2)
Summary
The loss of docosahexaenoic acid (DHA) from the retina or brain has been associated with a loss in nervoussystem function in experimental animals, as well as in human infants fed vegetable oil-based formulas. Infants who receive formulas with vegetable oil sources of essential fatty acids (EFA) have lower levels of brain DHA, with a compensatory increase in docosapentaenoic acid (22:5n-6, DPAn-6) [20,21,22]. Randomized, placebo-controlled studies of the effects on neural function of long chain polyunsaturate supplementation of infant formula have demonstrated a benefit for various functional measures, including visual acuity (23 – 26), cognitive tests [27, 28], visual recognition memory [29, 30], and a means-end problem-solving test [31] Taken together, these studies indicate that the lack of preformed DHA in the infant diet leads to losses in nervous system DHA that, in turn, leads to losses in brain and retinal functions. When the level of brain or retinal DHA falls, there are functional
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