STUDY ON THE MECHANISM OF MIR-140-5P ON ALLEVIATING CEREBRAL ISCHEMIA- REPERFUSION INJURY IN RATS BY TARGETING TLR4

To investigate the effect and mechanism of miR-140-5p on alleviating cerebral ischemia-reperfusion injury in rats by targeting TLR4.Rat models of cerebral ischemia-reperfusion injury (IRI) and neuronal cell models of oxygen-glucose deprivation and reoxygenation (OGD/R) were established. miR-140-5p expression in brain tissues of cerebral IRI rats was interfered by lentivirus vectors. Transient transfection technique was used to interfere with the miR-140-5p and TLR4 expressions in neuron OGD/R cell model. RT-PCR was used to detect the miR-140-5p and TLR4 mRNA expression. Tetrazole chloride (TTC) staining was used to detect the cerebral infarction area of cerebral IRI rats. Western Blot was used to detect the TLR4 and apoptosis-related proteins expressions in cells. The expression of interleukin -6(IL-6), IL-10 and TNF-alpha in brain tissue was detected by ELISA. The superoxide dismutase (SOD) and malondialdehyde (MDA) expressions in tissues was detected by electrochemiluminescence immunoassay. Apoptosis was detected by flow cytometry. The relationship between miR-140-5p and TLR4 was verified by double fluorescein reporter enzyme.miR140-5p was low expressed and TLR4 was high expressed in the cerebral IRI ratsbrain tissues and neurons OGD/R cell model. The development of cerebral IRI will lead to the aggravation of inflammatory reaction and oxidative stress reaction in brain tissue and increase the cerebral infarction area. Over-expression of miR-140-5p can effectively relieve inflammatory reaction and oxidative stress reaction in brain tissue of cerebral IRI rats and reduce cerebral infarction area. Over-expression of miR-140-5p in neuron OGD/R cells or inhibition of TLR4 expression can effectively inhibit the apoptosis of Ht22 cells, up-regulate the anti-apoptotic protein Bcl2expression, and down-regulate the pro-apoptotic proteins Bax and Caspase-3expressions. The double fluorescein reporter enzyme verified the targeted relationship between miR-140-5p and TLR4.miR-140-5p was low expressed in brain tissues of cerebral IRI rats. It can reduce cerebral IRI of rats by targeting TLR4, improve neurological function of rats, and inhibit apoptosis of neuronal cells. It may be a potential therapeutic target for cerebral IRI.