Differential distribution of DHA-phospholipids in rat brain after feeding: A lipidomic approach

On a per-weight basis, the brain is the organ richest in lipids, including a remarkable proportion of polyunsaturated fatty acids (PUFAs) of the omega 3 series, namely eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The cerebral effects of exogenous DHA likely depend on its degree of incorporation into neuronal phospholipids and on its distribution among the various brain structures, after intake. Hence, because PUFAs are not evenly distributed among the brain phospholipid classes and because the existence of class-specific phospholipases that regulate their turnover, we sought to investigate the incorporation of omega 3 PUFAs in selected brain areas regions and specific phospholipid classes. Rats (n=7) were administered, by oral gavage, 100mg/kg/d of a commercially available fish oil (containing ∼84% of long-chain omega 3 fatty acids, of which ∼38% of DHA and ∼46% of EPA). Control rats (n=7) received liquid paraffin. This treatment was continued for 30 days. Thereafter, we dissected three areas, namely the hippocampus, the striatum, and the cortex. Quantization of individual phospholipid classes and their molecular species was performed by ESI-MS/MS. Principal component analysis was used to examine the variation of the molecular lipid profiles (as percentage) induced by omega 3 supplementation. Our results show that provision of omega 3 fatty acids to rats results in their incorporation into brain phospholipids, the extent of which is lower in the striatum as compared with cortex and hippocampus. These data might in part explain the mixed therapeutic results obtained in neurological disorders, many of which are likely region-specific.