| Objective Quantitative study of SD rat sciatic nerve pinch injury model was performed to determine the degree of damage caused by different pressures on the sciatic nerve,and a model of III degree sciatic nerve injury in Sunderland V degree classification was established.Based on the sciatic nerve injury model of degree III,the effects of different frequencies of vibration stimulation on skeletal muscle atrophy after sciatic nerve clamp injury in rats,the relationship between functional recovery and behaviour,the changes of relevant nerve growth factors and the role of muscle satellite cells were studied.Method The pressure of JZ06 Cr 14cm hemostatic forceps was measured.The model was made with JZ06 Cr 14cm hemostatic forceps.32 healthy 4-week-old male Sprague Dawley rats were randomly divided into 4 groups: blank control group(8 rats)and hemostatic forceps 1-button pressure group(8 rats),2-button pressure group(8 rats),3-button pressure group(8 rats)and nerve conduction velocity(NCV)were measured30 minutes after modeling.The degree III sciatic nerve injury model was established by HE staining.After the model was established,144 male SD rats weighing about 180 g were randomly divided into four groups: sham-operated group(n=24)and model group(n=120).The model group was randomly divided into model control group(n = 24),sham intervention group(n = 24),3Hz frequency group(n = 24),8Hz frequency group(n = 24),13 Hz frequency group(n = 24).One week after the establishment of the model,different intervention methods were given for treatment.Behavioral indicators were detected at 7 days,14 days,21 days and 28 days after the treatment.Biochemical indicators were sacrificed at 7,14 and 28 days after treatment.Observation indicators: gastrocnemius muscle wet weight ratio;sciatic nerve function index;immunohistochemistry(muscle satellite cells;IGF-1;Myo D).Result1.Quantitative Study of Peripheral Nerve Injury Model(1)Pressure measurement of JZ06 Cr 14 cm hemostatic forceps shows that 1buckling pressure is about 16 N,2 buckling pressure is about 31 N and 3 buckling pressure is about 46 N.(2)The sciatic nerve was clamped with 16 N pressure.The nerve conduction velocity in 16 N pressure group(1 buckle pressure group)was significantly higher than that in blank group(P < 0.05).The morphology showed that the nerve fibers were arranged parallel and compact,and the axons,myelin sheaths and nerve intima bundle modes were intact without rupture.(3)The sciatic nerve was clamped with 31 N pressure.The nerve conduction velocity in 31 N pressure group(2 buckle pressure group)was significantly different from that in blank group and 16 N pressure group(P < 0.05).The morphology showed axonal breakage,complete perineurium,partial nerve fiber breakage,partial damage of nerve intima and structural disorder.(4)The sciatic nerve was clamped with 46 N pressure.The nerve conduction velocities in the 46 N pressure group(3-button pressure group)could not be measured.There was statistical significance between the 46 N pressure group and other groups(P< 0.05).The nerve fibers were broken in morphology,but the epineurium and bundle pattern remained intact.2.Effect of different frequency vibration methods on behaviour after sciatic nerve injury in rats(1)Oblique plate experiment showed that 3,8 and 13 Hz frequency vibration could promote the recovery of muscle strength after sciatic nerve injury in rats,which had statistical significance compared with sham intervention group(P < 0.05);at each treatment time point,3 Hz frequency group was always higher than other frequency group,and there was statistical significance between other groups at 28 days of treatment(P < 0.05).(2)SFI experimental statistics showed that 3,8 and 13 Hz frequency vibration could promote the recovery of gait and sciatic nerve function after sciatic nerve injury in rats,which had statistical significance compared with the sham intervention group(P < 0.05);at 14 days after treatment,the 8 Hz frequency group was at the highest level,and had no statistical significance compared with the 3 Hz frequency group(P >0.05);after 28 times of treatment,the 3 Hz frequency group and the 8,13 Hz frequency group had both.There was no significant difference between 8 Hz frequency group and 13 Hz frequency group(P > 0.05).3.Effects of different frequencies of vibration on gastrocnemius muscle atrophy after sciatic nerve injury in rats(1)The results of muscle wet weight ratio experiment showed that the frequencies of 3,8 and 13 Hz were higher than those of sham intervention group,suggesting that they could promote the repair of gastrocnemius muscle after sciatic nerve injury in rats.At 14 days of treatment,the frequencies of 13 Hz were higher than those of 3 and 8Hz,but there was no significant difference between them(P > 0.05).At 28 days of treatment,the level of 3Hz frequencies group was the highest,and there was statistical significance between the frequencies of 8 and 13 Hz groups.There was no significant difference between 8 Hz frequency group and 13 Hz frequency group(P > 0.05).(2)The results of positive expression of IGF-1 showed that the frequency of 3,8and 13 Hz was higher than that of sham intervention group,suggesting that it could promote the expression of IGF-1 in gastrocnemius muscle after sciatic nerve injury in rats.At 7 days of treatment,the frequency of 8 Hz was higher than that of 3 and 13 Hz,and there was a statistical difference with that of 13 Hz frequency group(P < 0.05);at28 days of treatment,the frequency of 3 Hz was the highest,and there was a unification between the frequency of 8 and 13 Hz groups.Meaning(P < 0.05).(3)The positive expression of Myo D in the 3,8 and 13 Hz frequency group was higher than that in the sham intervention group,suggesting that it could promote the expression of Myo D in gastrocnemius muscle after sciatic nerve injury in rats.At 7days of treatment,the 8 Hz frequency group was at the highest level,and there was a statistical difference between the 3 Hz frequency group and the 13 Hz frequency group(P < 0.05);at 14 days of treatment,the 13 Hz frequency group was at the highest level,and had a statistical difference with the 8 Hz frequency group(P < 0.05).At 28 days of treatment,the highest level was found in the 3Hz frequency group,but there was no significant difference between the other groups(P < 0.05).The positive expression of muscle satellite cells showed that the frequencies of 3,8and 13 Hz were higher than those of sham intervention group,suggesting that they could promote the division and proliferation of gastrocnemius muscle satellite cells after sciatic nerve injury in rats.On the 7th day of treatment,the 8Hz frequency group was at the highest level,and there were statistical differences among the frequency groups(P < 0.05);on the 14 th day of treatment,the 13 Hz frequency group was at the highest level,and there were statistical differences among the frequency groups(P <0.05);on the 28 th day of treatment,the 3Hz frequency group was at the highest level,and there were statistical differences among the frequency groups(P < 0.05).Conclusion1.About 16 N pressure sciatic nerve crush injury model meets Sunderland I degree damage.2.About 31 N pressure sciatic nerve crush injury model meets Sunderland II or III degree injury.3.About 46 N pressure sciatic nerve crush injury model meets Sunderland III degree injury.4.3,8,13 Hz frequency vibration method can increase the angle of rat oblique plate experiment,relieve muscle strength after peripheral nerve injury,improve lower limb muscle strength,lower vibration frequency can promote muscle strength recovery.5.3,8,and 13 Hz frequency vibration methods can increase the SFI value,improve the gait after sciatic nerve injury,and promote the recovery of motor function.6.The 3,8,and 13 Hz frequency vibration methods can effectively reduce the decrease of skeletal muscle muscle wet weight ratio,alleviate skeletal muscle atrophy and promote skeletal muscle repair.7.3,8,and 13 Hz frequency vibration methods can effectively promote the expression of IGF-1 and Myo D,accelerate the proliferation and differentiation of muscle satellite cells,and alleviate the skeletal muscle atrophy.8.Overall,3Hz frequency group can promote the recovery of muscle strength,improve gait after sciatic nerve injury,promote the recovery of motor function,accelerate the expression of IGF-1 and Myo D,accelerate the proliferation and differentiation of muscle satellite cells,and alleviate skeletal muscle atrophy.Phased observation showed that the rate of skeletal muscle repair by 3,8 and 13 Hz frequency vibration method varied in different treatment time,and appropriate treatment should be selected according to the treatment time. |
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