Gastrodin Inhibits Expression of Inducible NO Synthase, Cyclooxygenase-2 and Proinflammatory Cytokines in Cultured LPS-Stimulated Microglia via MAPK Pathways

Abstract

BackgroundMicroglial activation plays an important role in neurodegenerative diseases by producing several proinflammatory enzymes and proinflammatory cytokines. The phenolic glucoside gastrodin, a main constituent of a Chinese herbal medicine, has been known to display anti-inflammatory properties. The current study investigates the potential mechanisms whereby gastrodin affects the expression of potentially pro-inflammatory proteins by cultured murine microglial BV-2 cells stimulated with lipopolysaccharide (LPS).Methodology/Principal FindingsBV-2 cells were pretreated with gastrodin (30, 40, and 60 µM) for 1 h and then stimulated with LPS (1 µg/ml) for another 4 h. The effects on proinflammatory enzymes, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and proinflammatory cytokines, tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β), are analysed by double-immunofluorescence labeling and RT-PCR assay. To reveal the mechanisms of action of gastrodin we investigated the involvement of mitogen-activated protein kinases (MAPKs) cascades and their downstream transcription factors, nuclear factor-κB (NF-κB) and cyclic AMP-responsive element (CRE)-binding protein (CREB). Gastrodin significantly reduced the LPS-induced protein and mRNA expression levels of iNOS, COX-2, TNF-α, IL-1β and NF-κB. LPS (1 µg/ml, 30 min)-induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal protein kinase (JNK) and p38 mitogen-activated protein kinase (p38 MAPK) and this was inhibited by pretreatment of BV-2 cells with different concentrations of gastrodin (30, 40, and 60 µM). In addition, gastrodin blocked LPS-induced phosphorylation of inhibitor κB-α (IκB-α) (and hence the activation of NF-κB) and of CREB, respectively.Conclusion and ImplicationsThis study indicates that gastrodin significantly attenuate levels of neurotoxic proinflammatory mediators and proinflammatory cytokines by inhibition of the NF-κB signaling pathway and phosphorylation of MAPKs in LPS-stimulated microglial cells. Arising from the above, we suggest that gastrodin has a potential as an anti-inflammatory drug candidate in neurodegenerative diseases.

Propofol attenuates intermittent hypoxia induced up-regulation of proinflammatory cytokines in microglia through inhibiting the activation of NF-Bκ/p38 MAPK signalling

“…While suffering from inflammation, IκB is phosphorylated and subjected to degradation by proteasomes. Consequently, NF-κB will be disassociated from IκB and translocate into nucleus, followed by the activation of NF-κB-dependent proinflammatory molecules [6,7]. It has been demonstrated that propofol suppresses the IH-induced NF-κB activity by preventing the phosphorylation of IκB and accompanied by down-regulated secretion of proinflammatory cytokines in the vascular endothelial cells [16].…”

17β-estradiol attenuates homocysteine-induced oxidative stress and inflammatory response as well as MAPKs cascade via activating PI3-K/Akt signal transduction pathway in Raw 264.7 cells

“…MAPKs are implicated in the responses to a host of stimulus, such as proinflammatory cytokines, osmotic stress, heat shock, and mitogens, which regulate inflammation, proliferation, differentiation, mitosis, cell survival, and apoptosis [45]. It has also been shown that MAPKs play important roles in up-regulating the expression of classic proinflammatory enzymes iNOS, COX-2, and cytokines TNF-α and IL-1β in various types of cells treated with LPS [46][47][48]. It has long been recognized that inflammation significantly impacts bone turnover, and inflammatory cytokines such as IL-1, TNF-α, and M-CSF that are associated with osteoclastic bone loss [49].…”

GLP-2 Suppresses LPS-Induced Inflammation in Macrophages by Inhibiting ERK Phosphorylation and NF-κB Activation

“…This study analyzed the molecular mechanism by which GLP-2 suppresses inflammation following LPS stimulation in macrophages, and we found that GLP-2 significantly inhibited LPS-induced enhancement of pro-inflammatory enzymes (iNOS and COX-2) and pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) expression in macrophages at the mRNA and protein levels, which provides an underlying mechanism for the anti-inflammatory effects of GLP-2 in vitro. First, we examined the effect of GLP-2 on iNOS and COX-2 expression, which are two important inflammatory factors [9]. GLP-2 (10 -9…”

“…The synthesis of cytokines, such as TNF-α, IL-1β and IL-6, is mediated by NF-κB, as is the expression of COX-2 and iNOS [9]. In resting cells, NF-κB dimers are sequestered in the cytosol by inhibitory proteins of the IκB family [38].…”