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Abstract:
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Docosohexaenoic acid (DHA; 226n-3) is an omega-3 fatty acid critical for normal brain function. DHA in humans is
incorporated late in gestation and postnatally, during periods of rapid brain development. We hypothesized altered brain DHA levels in developing rats would correlate with altered neural function at maturity. We asked 1) if low brain DHA levels during gestation and development would yield changes in sensory cortex responsiveness at maturity, and 2) whether such changes could be reversed if the diet was supplemented with DHA at different developmental ages. Long-Evans rats were raised from conception on diets deficient or replete (controls) in alpha-linolenic acid (DHA precursor). The deficient diet in three additional groups of animals was supplemented with 4% DHA at one of three ages (P0-P35, P35-P70, or continuously after P21). After 90 days of age, monocular light flashes evoked activity of retina and visual cortex. Responses to stimuli of
graded intensities were evaluated across diet conditions. Weight gain during development and composition of brain fatty
acids also were determined. All diets yielded similar retinal responses. The deficient diet enhanced visual cortex responses relative to the control diet,
particularly in the portion of the response 100 – 300 ms after stimulus delivery. Extended periods of DHA supplementation
reversed these changes; reversal did not occur with shorter periods of supplementation. These findings suggest increased cortical excitability related to suboptimal brain DHA levels may be addressed by supplementing the diet with DHA, but an extended period of supplementation may be required. (funding: Lied Foundation) |
