Eicosapentaenoic acid and gamma-linolenic acid increase hippocampal concentrations of IL-4 and IL-10 and abrogate lipopolysaccharide-induced inhibition of long-term potentiation

Abstract 

Inflammatory changes in brain exert a negative impact on cognitive function and in animal studies, these changes are associated with impairment in hippocampal-dependent learning paradigms and in long-term potentiation (LTP), which is a putative biological substrate for learning and/or memory. Lipopolysaccharide (LPS), a component of the cell wall of gram negative bacteria, induces inflammatory changes in the brain and leads to impairment of LTP. Since eicosapentaenoic acid (EPA) inhibits LPS-induced changes in vitro, we assessed the possibility that treatment of rats with EPA, alone or in combination with gamma-linolenic acid (GLA) might inhibit LPS-induced changes in vivo. The data presented indicate that the LPS-induced inhibition of LTP and decrease in hippocampal concentration of anti-inflammatory cytokines IL-10 and IL-4 are blocked in rats treated with EPA, GLA or both. The evidence suggests that these effects may be coupled with fatty acid-induced up-regulation of peroxisome proliferator-activated receptor-gamma which possesses known anti-inflammatory effects.