Oxymatrine Promotes Axonal Regeneration In Experimental Cerebral Infarction Mice And Its Mechanism Study

Objective: To explore whether oxymatrine(OMT)can promote the recovery of neurological function and the axonal regeneration after cerebral infarction in mice and explore its potential mechanism.Methods:Male,healthy C57BL/6 mice were randomly divided into Sham operation group(sham),vehicle control group(vehicle)and OMT treatment group(OMT).All the mice were subjected to distal middle cerebral artery occlusion(dMCAO)except to sham group.Equal volume distilled water or different doses of oxymatrine solution were intraperitoneally injected 24 hours after surgery,once a day for 14 days.Rota-rod test and grid walking test were performed at day 3,day 7,day 14,and day 28 after surgery.An optimal dose that promotes recovery of neurological function was determined based on the results.Biotinylated dextran amines(BDA)2 ?l were injected into the contralateral sensorimotor cortex of the mice in all groups at day 14 after surgery.The cell bodies and neurites of BDA-labeled neuron in bilateral cortex of the mice were detected at day 28 after surgery.Brain tissues were collected at day 3,day 7,day 14,and day 28 after surgery.The expression of Gap-43 in the peri-infarcted cortex was measured by immunofluorescence.The protein expression of Gap-43,BDNF and GDNF in peri-infarcted cortex was assayed by western blotting.Results:1.The results of behavioral experiment indicated that OMT could significantly improve the motor function and reduce the ratio of footfault of cerebral infarction mice.The middle dose(125 mg/kg)OMT group had the best effect.This dosage of OMT was chosen for subsequent experiments.2.Gap-43 immunofluorescence staining showed that the expression of Gap-43 protein increased in the cortex around the infarct at different stages after cerebral infarction.The expression of Gap-43 protein in OMT group was significantly higher than that in vehicle group(P < 0.05).The difference was statistically significant.Those suggest that OMT could promote axonal regeneration in the cortex around the infarct.3.In ipsilesional cortex,there were fewer BDA-labeled axonal fibers in sham group,and more BDA-labeled axonal fibers in vehicle group and OMT group.BDA-labeled axonal fibers in OMT group were much more than that in vehicle group(P < 0.05).In injection lateral cortex,long BDA-labeled axonal fibers can be found extending to the cortex around the infarct in OMT group mice,suggesting that OMT could promote the extension of new axons from the contralateral cortex to the infarct cortex.4.Western blotting results showed that,compared with vehicle group,the expression of Gap-43 protein in OMT group increased at 7 and 14 days after surgery(P < 0.05);the expression of BDNF protein increased at 3,7 and 14 days after surgery(P < 0.05);the expression of GDNF protein increased at 3 and 7 days after surgery(P < 0.05).Conclusions:1.Delayed treatment with OMT(125 mg/kg)after cerebral infarction in mice can significantly improve motor function.2.Delayed treatment with OMT after cerebral infarction in mice can increase the axonal regeneration in the cortex.3.OMT promote axonal regeneration may be achieved by up-regulating the expression of BDNF and GDNF in brain tissue.