THE EFFECT OF MIR-206 ON MOTOR AND COGNITIVE FUNCTION IN RATS WITH CEREBRAL INFARCTION BY DOWN REGULATING BDNF

Lisha Yang¹, Wanfei Li², Xiaoou Ji³, Guofeng Shi^{1, *}

¹School of Nursing, Guizhou University of Traditional Chinese Medicine, Guiyang, Guizhou, China - ²School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China - ³Care management, Centers Plan for Healthy Living, Staten Island, NY, U.S.

Objective: To explore the relationship between miR-26 and brain-derived neurotrophic factor (BDNF), and the role of miR-26 in the neural function of rats with cerebral infarction (CI). 

Methods: The CI rat model was constructed by using cerebral artery ischemia/reperfusion. The triphenyltetrazolium chloride (TTC) method was used to detect the infarct area of rats in each group to determine whether the model was successfully constructed. At the same time, RT-qPCR was used to detect the transcription level of miR-206 and BDNF in the brain tissue of rats in each group. We then tested the luciferase activity of co-transfected miR-206 and BDNF 3`UTR plasmid ha cells by using double luciferase assay. To further verify the relationship between miR-206 and BDNF and the regulatory mechanism, we constructed the low expression HA cells of miR-206 by using an miR-206 inhibitor and constructed the in vitro model by anoxia/reoxygenation. Meanwhile, RT-qPCR was used to detect the transcription level of miR-206 and BDNF in each group of cells, and Western Blotting and TURNEL staining was used to detect the apoptosis level of each group of cells, as well as the expression of related apoptosis proteins and TrkB-Akt pathway related proteins. To further explore the role of miR-206 and BDNF in the motor and cognitive function recovery of rats with CI, we injected BDNF into the brain to intervene in the animal model, and detected the CI area of the model group and BDNF group by the TTC method, following which we observed the motor and cognitive ability recovery level of rats by neurological deficit score. 

Results: First, we confirmed the successful implementation of the brain infarction rat model through a TTC experiment. At the same time, RT-qPCR showed that the BDNF level was significantly down regulated and the miR-206 level was down regulated, which was negatively correlated. In addition, luciferase report showed that miR-206 could directly exert negative regulation on BDNF. RT-qPCR results revealed that the BDNF expression of hypoxia/reoxygenation HA cells was significantly up-regulated by the miR-206 inhibitor, whereas turn results showed that the apoptosis level of miR-206 inhibitor group was significantly reduced, and Western Blotting results showed that the ratio of Bax/Bcl-2 of apoptosis protein was significantly reduced, with the expression of TrkB and pAkt being significantly increased. Furthermore, the animal level indicated that the injection of BDNF into the brain could significantly improve the area of CI and promote the recovery of motor and cognitive function in rats with CI. 

Conclusion: miR-206 can inhibit the recovery of motor and cognitive function in rats with CI by down regulating the BDNF and TrkB-Akt pathway.