Causal Link between n-3 Polyunsaturated Fatty Acid Deficiency and Motivation Deficits

Reward-processing impairment is a common symptomatic dimension of several psychiatric disorders. However, whether the underlying pathological mechanisms are common is unknown. Herein, we asked if the decrease in the n-3 Polyunsaturated Fatty Acids (PUFAs) lipid species, consistently described in these pathologies, could underlie reward-processing deficits. We show that reduced n-3 PUFA biostatus in mice leads to selective motivational deficits. Electrophysiological recordings revealed increased collateral inhibition of dopamine D2 receptor (D2R)-expressing medium spiny neurons (iMSNs) onto dopamine D1 receptor-expressing (d)MSNs in the nucleus accumbens, a main brain region for the modulation of motivation. Strikingly, transgenically preventing n-3 PUFA deficiency selectively in D2R-expressing neurons normalizes MSNs collateral inhibition and enhances motivation. These results constitute the first demonstration of a causal link between a behavioral deficit and n-3 PUFA decrease in a discrete neuronal population and suggest that lower n-3 PUFA biostatus in psychopathologies could participate to the etiology of reward-related symptoms.