Long-Chain Polyunsaturated Fatty Acids Modulate Interleukin-1β–Induced Changes in Behavior, Monoaminergic Neurotransmitters, and Brain Inflammation in Rats ,

Abstract

Recent evidence has suggested that an imbalance between membrane (n-3) and (n-6) fatty acids may contribute to the etiology of autoimmune and neurodegenerative diseases. In this study, the mechanisms by which eicosapentaenoic acid (EPA), γ-linolenic acid (GLA), and arachidonic acid (AA) modulate neurotransmitters, behavior, and brain inflammation were evaluated in rats that received central saline or interleukin-1 β (IL-1) administrations. In rats treated with saline, only the AA-enriched diet significantly increased anxiety-like behavior in the elevated plus maze, which was associated with increased corticosterone secretion. AA also increased the turnover of dopamine (DA), noradrenaline (NA), and serotonin (5-HT) in the amygdala and increased the prostaglandin (PG)E2 level in the hippocampus. IL-1 administration slowed rat learning in the water maze and increased anxiety-like behavior, changes which were associated with increased homovanillic acid and 5-HT turnover, decreased NA in the hippocampus and amygdala, decreased DA in the frontal cortex, and decreased IL-10 in limbic brain regions. Increased corticosterone secretion following IL-1 administration was accompanied by increased NA turnover in the hippocampus (P < 0.05) and increased PGE2 concentration (P < 0.01) in the limbic brain regions. Of the 3 diets tested, only EPA attenuated IL-1–induced behavioral changes (P < 0.05 or 0.01), which was associated with the modulation of EPA on the neuroendocrine and immune changes induced by IL-1. GLA reduced hippocampal PGE2 concentration in rats given IL-1 (P < 0.01). AA did not counteract any of the changes induced by IL-1. These results suggest that EPA, GLA, and AA play different roles in the neuroendocrine-immune network.