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Gamma-Linolenic Acid Inhibits Inflammatory Responses by Regulating NF-κB and AP-1 Activation in Lipopolysaccharide-Induced RAW 264.7 Macrophages

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Gamma linolenic acid (GLA) is a member of the n-6 family of polyunsaturated fatty acids and can be synthesized from linoleic acid (LA) by the enzyme delta-6-desaturase. The therapeutic values of GLA supplementation have been documented, but the molecular mechanism behind the action of GLA in health benefits is not clear. In this study, we assessed the effect of GLA with that of LA on lipopolysaccharide (LPS)-induced inflammatory responses and further explored the molecular mechanism underlying the pharmacological properties of GLA in mouse RAW 264.7 macrophages. GLA significantly inhibited LPS-induced protein expression of inducible nitric oxide synthase, pro-interleukin-1β, and cyclooxygenase-2 as well as nitric oxide production and the intracellular glutathione level. LA was less potent than GLA in inhibiting LPS-induced inflammatory mediators. Both GLA and LA treatments dramatically inhibited LPS-induced IκB-α degradation, IκB-α phosphorylation, and nuclear p65 protein expression. Moreover, LPS-induced nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) nuclear protein–DNA binding affinity and reporter gene activity were significantly decreased by LA and GLA. Exogenous addition of GLA but not LA significantly reduced LPS-induced expression of phosphorylated extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK)-1. Our data suggest that GLA inhibits inflammatory responses through inactivation of NF-κB and AP-1 by suppressed oxidative stress and signal transduction pathway of ERK and JNK in LPS-induced RAW 264.7 macrophages.

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activator protein-1




electrophoretic mobility shift assay


extracellular signal-regulated kinase1/2


glyceraldehydes-3-phosphate dehydrogenase


gamma-linolenic acid






inducible form of NOS


internal standard


c-Jun NH2-terminal kinase


linoleic acid




mitogen-activated protein kinase


3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide


nuclear factor-κB


nitric oxide


nitric oxide synthase

PGE2 :

prostaglandin E2


phenylmethylsulfonyl fluoride


recombinant RNA


reverse transcriptase polymerase chain reaction


secretory alkaline phosphatase


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This research was funded by the National Science Council, Republic of China, under Grant NSC 95-2320-B-040-034 and by Chung Shan Medical University, under Grant CSMU 94-OM-B-003.

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Correspondence to Kai-Li Liu.

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Cheng-Shu Chang and HaiLun Sun contributed equally to this work.

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Chang, CS., Sun, HL., Lii, CK. et al. Gamma-Linolenic Acid Inhibits Inflammatory Responses by Regulating NF-κB and AP-1 Activation in Lipopolysaccharide-Induced RAW 264.7 Macrophages. Inflammation 33, 46–57 (2010).

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