| Objective To investigate the effects of high-frequency repetitive transcranial magnetic stimulation (rTMS) with different intensity on the motor evoked potential (MEP)of rats with cerebral infarction, so as to explore the probable mechanism.Methods 43 rats were randomly divided into blank control group(n=7), middle cerebral artery occlusion(MCAO)model control group(n=7), sham stimulation control group(n=8) and rTMS group which was divided into 3 subgroups 80% MT group, 100% MT group and 120% MT group(n=21, each subgroup n=7). Firstly,determined resting motor threshold (MT) of another 12 rats, then established right middle cerebral artery occlusion (MCAO) model except the blank control group. After the model was made successfully 24 hours, 14 successive blocks of rTMS was given at 20 Hz of 2 seconds duration, 28 seconds intermittent time and 1200 total number of pulses in all the rTMS subgroups and the sham control group in corresponding intensity. The sham stimulation control group was given the same frequency and intensity as the 100% MT group with the coil perpendicular to the scalp of the same area. The model control group and the blank control group didn't receive any special treatment. Before the MCAO operation, 1 day after operation, 7 days after stimulation and 14 days after stimulation, the central motor conduction time (CMCT) and cortical latency (CL) was detected to observe the changes in electrophysiology.Results Before the MCAO operation ,CMCT and CL between both sides had no significantly difference in each group(P>0.05). 1 day after operation, both CMCT and CL on the left side was significantly reduced as compared with the right side and operation before(P<0.01). 7 days after stimulation, CMCT and CL on both sides had on difference between the groups , also each group had on difference on the two sides(P>0.05). 14 days after stimulation, CMCT and CL on the left side was reduced as compared with the blank control group and 7 days after stimulation in 100% MT group(P<0.05), both sides in which also reduced as compared with operation before (left P<0.01 and right P<0.05 ), CMCT and CL on the right side was reduced as compared with 1 day after operation in 80% MT group(P<0.05).Conclusions 20 Hz rTMS might promote the balance of the contralesional and ipsilesional hemisphere or evoke the unaffected hemisphere to compensate the functional impairments of the affected hemisphere through the decrease of CMCT and CL on both sides. RTMS of 80% MT and 100% MT seem to have the best effect. Objective To investigate the behavioral effects and the expression of Glial fibrillary acidic protein (GFAP) in the ischemic penumbra, so as to explore the probable mechanism of 20 Hz repetitive transcranial magnetic stimulation (rTMS) with different intensity in rats with cerebral infarction.Methods 43 rats were randomly divided into blank control group(n=7), middle cerebral artery occlusion(MCAO)model control group(n=7), sham stimulation control group(n=8) and rTMS group which was divided into 3 subgroups 80% MT group, 100% MT group and 120% MT group(n=21, each subgroup n=7). The cerebral infarction model was established by right middle cerebral artery occlusion in each group except the blank control group. After the MCAO model was made successfully 24 hours, the 3 rTMS subgroup and the sham control group were given 14 successive blocks of 20 Hz rTMS in corresponding intensity. The sham stimulation control group was given the same frequency and intensity as the 100% MT group with the coil perpendicular to the scalp of the same area. The model control group and the blank control group didn't receive any special treatment. Functional assessments were detected at 3 different time points. After 14 days'treatment, the expression of GFAP protein in the ischemic penumbra was tested in immunohistochemistry.Results Functional outcome was better in 100% MT group after 14 days stimulation than 1 day after operation reflected from 3 behavioral tests, while the other MCAO groups just better in 2 behavioral tests. The expression of GFAP in the 3 rTMS subgroups was all less than the model control group. Conclusions 20 Hz rTMS in 80% MT and 100% MT might be safe and effective to improve the functional outcome, especially in the 100% MT. The expression of GFAP decrease in the ischemic penumbra might be one of the mechanisms of the beneficial effect of rTMS in ischemia brain injury. Objective To investigate the effects of high-frequency repetitive transcranial magnetic stimulation (rTMS) with different intensity on the brain ultrastructure in the ischemic penumbra and expression of brain-derived neurotrophic factor of rats with permanent middle cerebral artery occlusion (MCAO), so as to explore the probable mechanism.Methods 42 rats were randomly divided into blank control group, MCAO model control group, sham stimulation control group, rTMS group which was divided into 3 subgroups 80% MT group, 100% MT group and 120% MT group(n=7 in each group). The cerebral infarction model was established by right MCAO. RTMS treatment was given after the MCAO model was made successfully 24 hours. The 3 rTMS subgroup and the sham control group were given 14 successive blocks of 20 Hz rTMS in corresponding intensity. The sham stimulation control group was given the same frequency and intensity as the 100% MT group with the coil perpendicular to the scalp of the same area. The model control group and the blank control group didn't receive any special treatment. After 14 days'treatment, transmission electron microscope was used to investigate the ultrastructure in the ischemic penumbra, and immunohistochemical and Western blot methods were used to detect the expression of brain-derived neurotrophic factor.Results Damage reflected from the ultrastructure in the 3 rTMS subgroups was lower than the model control group and the sham stimulation control group. Expression of BDNF protein in the Western blot test was significantly increased in the 100% MT group and the blank control group as compared with which in the sham stimulation control group (P<0.01 and P<0.05, respectively), while the blank control group and the 3 rTMS subgroups had no statistically significant difference in comparison with the MCAO model control group (P>0.05). Aslo, the expression of BDNF protein in the immunohistochemical detection had no statistically significant difference between all the groups (P>0.05).Conclusions 20 Hz rTMS might promote the recovery of the ultrastructure of neural tissues in the acute cerebral ischemic and enhance the expression of BDNF in the ipsilesional hemisphere especially in the 100% MT intensity, which might be one of the mechanisms of rTMS in the treatment of ischemia brain injury. |
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