title: Docosahexaenoic acid suppresses neuroinflammatory responses and induces heme oxygenase-1 expression in BV-2 microglia: implications of antidepressant effects for ω-3 fatty acids.
abstract: Accumulating evidence suggests that the pathophysiology of depression might be associated with neuroinflammation, which could be attenuated by pharmacological treatment for depression. Omega-3 polyunsaturated fatty acids (PUFAs) are anti-inflammatory and exert antidepressant effects. The aim of this study was to identify the molecular mechanisms through which docosahexaenoic acid (DHA), the main omega-3 PUFA in the brain, modulates oxidative reactions and inflammatory cytokine production in microglial and neuronal cells. The results of this study showed that DHA reduced expressions of tumor necrosis factor-α, interleukin-6, nitric oxide synthase, and cyclo-oxygenase-2, induced by interferon-γ, and induced upregulation of heme oxygenase-1 (HO-1) in BV-2 microglia. The inhibitory effect of DHA on nitric oxide production was abolished by HO-1 inhibitor zinc protoporphyrin IX. In addition, DHA caused AKT and ERK activation in a time-dependent manner, and the DHA-induced HO-1 upregulation could be attenuated by PI-3 kinase/AKT and MEK/ERK inhibitors. DHA also increased IKKα/β phosphorylation, IκBα phosphorylation, and IκBα degradation, whereas both nuclear factor-κB and IκB protease inhibitors could inhibit DHA-induced HO-1 expressions. The other major n-3 PUFA, eicosapentaenoic acid, showed similar effects of DHA on inflammation and HO-1 in repeated key experiments. In connecting with inflammation hypothesis of depression and clinical studies supporting the antidepressant effects of omega-3 PUFAs, this study provides a novel implication of the antidepressant mechanisms of DHA.
authors.affiliation: Graduate Institute of Neural and Cognitive Sciences, China Medical University, Taichung, Taiwan.
authors.forename: Dah-Yuu
authors.initials: DY
authors.lastname: Lu
authors.forename: Yin-Yin
authors.initials: YY
authors.lastname: Tsao
authors.forename: Yuk-Man
authors.initials: YM
authors.lastname: Leung
authors.forename: Kuan-Pin
authors.initials: KP
authors.lastname: Su
mesh_terms: D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology* / Q000627:therapeutic use; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004281:Docosahexaenoic Acids / Q000494:pharmacology* / Q000627:therapeutic use; D004790:Enzyme Induction / Q000187:drug effects / Q000502:physiology; D015525:Fatty Acids, Omega-3 / Q000494:pharmacology / Q000627:therapeutic use; D015971:Gene Expression Regulation, Enzymologic; D051547:Heme Oxygenase-1 / Q000096:biosynthesis*; D007249:Inflammation / Q000201:enzymology / Q000473:pathology / Q000517:prevention & control; D051379:Mice; D017628:Microglia / Q000187:drug effects* / Q000201:enzymology* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000928:Antidepressive Agents; D015525:Fatty Acids, Omega-3; D004281:Docosahexaenoic Acids; D051547:Heme Oxygenase-1