The inhibitory effect of Gualou Guizhi Decoction on post-ischemic neuroinflammation via miR-155 in MCAO rats

Abstract

Gualou Guizhi Decoction (GLGZD) is commonly used to treat stroke. The present study investigated the potential roles of GLGZD on inflammation involving microRNA-155 (miR-155) in a model of ischemic stroke using middle cerebral artery occlusion (MCAO) rats. Sprague-Dawley rats were randomly divided into three groups: Sham operated group, MCAO model group, and GLGZD treatment group. The ischemic model was established by 2 h left MCAO followed by reperfusion. Neurological deficits were evaluated with a modified Ashworth scale in each group. The changes in individual paw parameters were assessed by Catwalk gait analysis. Inflammatory cytokines were measured by enzyme linked immunosorbent assay (ELISA) and protein levels and gene expression related to inflammation were detected by Western blot and quantitative reverse transcription-PCR (qRTPCR) assays, respectively. The expression of inflammatory signaling proteins was additionally detected by immunohistochemistry. Treatment of MCAO rats with GLGZD improved neuronal defects and limb motivity. Additionally, GLGZD was able to inhibit miR-155 upregulation, resulting in down-regulation of miR155-targeted molecules in MCAO rats, including suppressor of cytokine signaling 1 (SOCS1), inhibitor of nuclear factor kappa-B kinase (IKK), mothers against decapentaplegic homolog 2 (SMAD2) and CCAAT/ enhancer binding protein beta (CEBPβ). Meanwhile, the production of anti-inflammatory cytokines was dramatically enhanced by GLGZD treatment when comparing with the MCAO model group. In conclusion, GLGZD down-regulates miR-155, mediating subsequent neuroinflammation and resulting in neuroprotection which contributes to reduced spasticity after ischemic stroke.