Scutellarin Exerts Anti-Inflammatory Effects in Activated Microglia/Brain Macrophage in Cerebral Ischemia and in Activated BV-2 Microglia Through Regulation of MAPKs Signaling Pathway
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Scutellarin, an herbal compound, can effectively suppress the inflammatory response in activated microglia/brain macrophage(AM/BM) in experimentally induced cerebral ischemia; however, the underlying mechanism for this has not been fully clarified. We sought to elucidate if scutellarin would exert its anti-inflammatory effects on AM/BM through the MAPKs pathway.
Materials and Methods
Western blot and immunofluorescence labeling were used to determine the expression of the MAPKs pathway in AM/BM in rats subjected to middle cerebral artery occlusion (MCAO) also in lipopolysaccharide (LPS)-activated BV-2 microglia in vitro. Furthermore, expression of p-p38 along with that of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta(IL-1β), and inducible nitric oxide synthase (iNOS) in LPS-activated microglia subjected to pretreatment with p38 inhibitor SB203580, p38 activator sc-201214, scutellarin, or a combination of them was evaluated.
Scutellarin markedly attenuated the expression of p-p38, p-JNK in AM/BM in MCAO rats and in vitro. Conversely, p-ERK1/2 expression level was significantly increased by scutellarin. Meanwhile, scutellarin suppressed the expression of proinflammatory mediators including iNOS, TNF-α, and IL-1β in AM/BM. More importantly, SB203580 suppressed p-p38 protein expression level in LPS-activated BV-2 microglia that was coupled with decreased expression of proinflammatory mediators (TNF-α, iNOS) in LPS-activated BV-2 microglia. However, p38 activator sc-201214 increased expression of proinflammatory mediators TNF-α, iNOS, and IL-1β. Interestingly, the decreased expression of both proinflammatory markers by p38 MAPK inhibitor and increased expression of proinflammatory markers by p38 MAPK activator were compatible with that in BV-2-activated microglia pretreated with scutellarin.
The results suggest that scutellarin down-regulates the expression of proinflammatory mediators in AM/BM through suppressing the p-JNK and p-p38 MAPKs. Of note, the anti-inflammatory effect of p38 MAPK inhibitor and scutellarin is comparable. Besides, p38 MAPKs activator reverses the effect of scutellarin. Additionally, scutellarin increases p-ERK1/2 expression that may be neuroprotective.
KeywordsScutellarin Activated microglia/brain macrophage MAPKs pathway Proinflammatory mediators Anti-inflammation
Central nervous system
Dulbecco’s modified Eagle’s medium
Extracellular signal-regulated kinase1/2
Fetal calf serum
Gastrodia elata Blume
Glycogen synthase kinase-3 beta
Inducible nitric oxide synthase
c-Jun N-terminal kinase
Mitogen-activated protein kinases
Mitochonic acid 5
Middle cerebral artery occlusion
Phosphate buffered saline
Phosphorylated c-Jun N-terminal kinase
- p38 MAPK
p38 mitogen-activated protein kinase
Phosphorylated extracellular signal-regulated kinase1/2
- SD rats
Tumor necrosis factor-alpha
Activated microglia/brain macrophage
This study was supported by National Natural Science Foundation of China (Project Number 31760297, Y Yuan), Applied Basic Research Projects of Yunnan Province (Project Number 2018FE001(-189)). It was also supported by Applied Basic Research Program Key Projects of Yunnan Province (Project Number 2015FA020, C-Y Wu), National Natural Science Foundation of China (Project Number 31260254, C-Y Wu).
Compliance with Ethical Standards
Conflict of interest
All authors declare that they have no conflict of interest.
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