The ganglioside profile of mouse brain does not respond to changes in dietary n-3 polyunsaturated fatty acid supply

Long chain polyunsaturated fatty acids (LC-PUFAs) of the n-3 and n-6 families are major components of brain lipids, both in terms of levels and biological significance. They play crucial roles in various neurological processes. The brain is largely dependent on food supply of LC-PUFAs and its lipid composition can be modulated by changes in dietary intake. Sufficient dietary supply of the n-3 LC-PUFAs as well as a balanced n-6/n-3 ratio are required for proper brain development and function. As dietary intervention using n-3 LC-PUFAs is considered a promising therapeutic approach to prevent or treat brain disorders, it is important to understand the associated biochemical changes as well as the mechanisms underlying the biological effects. In the present study, we performed lipidomic analyses to document the effects of dietary n-3 LC-PUFA supply on the composition of two families of FA-carrying complex membrane lipids playing important roles in the nervous system: phospholipids and gangliosides. We show that an unbalanced, n-3 LC-PUFA-deficient diet, from gestation to adulthood in mice resulted in decreased levels of docosahexaenoic acid (DHA, C22:6n-3) and increased levels of docosapentaenoic acid (DPA, C22:5n-6) in brain phospholipids, while a n-3 LC-PUFA-supplemented diet was associated with the reverse phenotype. However, the composition of brain gangliosides, which carry mainly saturated and mono-unsaturated fatty acids, was unaffected by the diet, suggesting that they do not directly contribute to mediating the neurological effects of dietary n-3 LC-PUFA manipulation.