Up-regulation of lncRNA NEAT1 in cerebral ischemic stroke promotes activation of astrocytes by modulation of miR-488-3p/RAC1

We aim to research the molecular mechanism of lncRNA NEAT1 in the activation of astrocytes in a cerebral ischemia-reperfusion injury model. Mouse model of cerebral ischemia-reperfusion injury was constructed, and shNEAT1 was transfected. The infarct area, brain water content, and neurological deficiency were detected. Immunofluorescence detection and fluorescence in situ hybridization (FISH) assay were processed to detect glial fibrillary acidic protein (GFAP) expression. Astrocyte cells were cultured for oxygen-glucose deprivation/re-oxygenation (OGD)/re-oxygenation model construction. After treatment by shNEAT1, miR-488-3p mimic, miR-488-3p inhibitor, Q-PCR assay, western blot and ELISA were undertaken to detect the expressions of NEAT1, miR-488-3p, RAC1, inflammatory cytokines, RAC1 and GFAP. Dual luciferase reporter assay and RNA-binding protein immunoprecipitation (RIP) assay were used to verify the binding of NEAT1, miR-488-3p and RAC1. The expression of NEAT1 in brain tissue was significantly higher than that in Sham operation group. Knockdown of NEAT1 inhibited the brain damage caused by middle cerebral artery occlusion (MCAO) treatment, reduced the inflammatory response, and suppressed the activation of astrocytes. By constructing an in vitro OGD/R cell model, it was found that NEAT1 knockdown also inhibited the activation of astrocytes caused by OGD/R. Knockdown of NEAT1 caused the up-regulation of miR-488-3p and the down-regulation of RAC1. Knockdown of miR-488-3p or over-expression of RAC1 reversed the inhibitory effect of shNEAT1 on OGD/R-induced astrocyte activation. Over-expression of NEAT1 in cerebral ischemic stroke promotes activation of astrocytes by modulation miR-488-3p/RAC1, which is proved in vitro. Our study may provide a new idea for the diagnosis and treatment of MCAO.

The analgesic activities of total alkaloids of the ethnic medicine Cynanchum komarovii Al. Iljinski

ETHNOPHARMACOLOGICAL RELEVANCE

Cynanchum komarovii Al. Iljinski is a ethnomedicinal herb and this ethno-medicine is used mainly to treat arthritis, toothache, reducing phlegm, relieving cough. Total alkaloids of Cynanchum komarovii Al. Iljinski (TACKI) is the main active compound of Cynanchum komarovii Al. Iljinski. Previous investigations have revealed that TACKI can significantly inhibit rat foot swelling caused by carrageenan; it has a significant inhibitory effect on granulation tissue proliferation. Pharmacology study showed that Cynanchum komarovii Al. Iljinski has analgesia, anti-inflammatory, antibacterial, anti-tumor, relieving cough and relieving asthma. However, there is no any investigation on the mechanism of analgesia and anti-inflammation.

AIM OF THE STUDY

To clarify the analgesic effect and material basis of Cynanchum komarovii Al. Iljinski, determine the analgesic effect of TACKI, and provide experimental data support for its traditional application in the treatment of various pains.

MATERIALS AND METHODS

TACKI were prepared by the traditional acid extraction and alkaline precipitation method, and TACKI was analyzed through classic animal models of acute antinociceptive animal models and chronic antinociceptive. Evaluation of analgesic effects, and preliminary discussion of the mechanism of its analgesic effects were performed in this work.

RESULTS

Acute toxicity experiments showed that the LD₅₀ of TACKI mice was 2960.88 mg/kg, and symptoms of poisoning appeared. Patholog of liver and kidney studies have shown that TACKI reduces eosinophils and increases basophils in kidney glomeruli. In the study of analgesic effects, TACKI had analgesic activity through the PWL, formalin test, and acetic acid writhing test. In the chronic inflammatory antinociceptive study, the latency of the withdrawal reflex in the TACKI group was prolonged, and the mechanical withdrawal reflex threshold was significantly increased. The protein expression of NMDA, GFAP and Iba-1 in rat brain tissue can be reduced significantly byTACKI. Meanwhile, the content of TNF-α and IL-6 in rat brain tissue is reduced.

CONCLUSION

TACKI has a significant analgesic activities. It may be related to inhibiting the activation of astrocytes and reducing the content of inflammatory mediators.