DHA involvement in neurotransmission process

International audience; The very high enrichment of the nervous system in the polyunsaturated fatty acids, arachidonic (AA, 20: 4n-6) and docosahexaenoic acids (DHA, 22: 6n-3), is dependant of the dietary availability of their respective precursors, linoleic (18: 2n-6) and_-linolenic acids (18: 3n-3). Inadequate amounts of DHA in brain membranes have been linked to a wide variety of abnormalities ranging from visual acuity and learning irregularities, to psychopathologies. However, the molecular mechanisms involved remain unknown. Several years ago, we hypothesized that a modification of DHA contents of neuronal membranes by dietary modulation could change the neurotransmission function and then underlie inappropriate behavioural response. We showed that, in parallel to a severe loss of brain DHA concomitant to a compensatory substitution by 22:5n-6, the dietary lack of α-linolenic acid during development induced important changes in the release of neurotransmitters (dopamine, serotonin, acetylcholine) in cerebral areas specifically involved in learning, memory and reward processes. Data suggested alteration of presynaptic storage process and dysregulations of reciprocal functional interactions between monoaminergic and cholinergic pathways. Moreover, we showed that recovery of these neurochemical changes was possible when the deficient diet was switched to a diet balanced in n-3 and n-6 PUFA before weaning. The next step is to understand the mechanism involved. Particularly, we focus on the study of the metabolic cooperation between the endothelial cell, the astrocyte and the neuron which regulate synaptic transmission.These works could contribute to the understanding of the link between some neuropsychiatric disorders and the metabolism of n-3 PUFA, through their action on neurotransmission.