Developmental sensitivity of the piglet brain to docosahexanoic acid

Abstract

Human formula-fed infants have a lower concentration of docosahexanoic acid (DHA) in cerebral cortex compared with breast-fed infants. It is uncertain whether this biochemical deficit is reversible in later infancy. We used a piglet model to determine whether a critical window exists for the deposition of DHA in cerebral cortex during early postnatal development. Milk formula supplemented with DHA was fed to piglets for one of two 14-day periods commencing at either 2 or 16 d of life (early or late supplementation). Comparison of cortical DHA levels in response to supplemented formula was made with age-matched piglets receiving a control formula devoid of DHA. The level of DHA incorporated into whole brain during supplemented formula-feeding seemed to be less with increasing postnatal age. However, when cerebral cortex was examined, dietary DHA was efficiently incorporated during both early and late supplementation periods. Thus, analysis of whole brain was misleading, emphasizing the need to consider the effect of myelination when interpreting developmental changes in brain fatty acids. We conclude that the piglet cerebral cortex is responsive to dietary DHA during the postnatal phase of the brain growth spurt. The lower cortical DHA levels of human formula-fed infants may, therefore, be reversible in later infancy. Plasma phospholipid DHA levels were approximately doubled and liver phospholipid DHA levels increased 50% relative to starting values during control formula-feeding. This suggests a higher rate of DHA synthesis in the piglet in comparison with the human infant, which may be an important limitation of the piglet model.