CGRP Protein In Anterior Horn Of Spinal Cord In Rats After Brachial Plexus Root Avulsion Injury

Objective:To explore the effects of puerarin,an extract of radix puerariae,on the expression of GFAP,iNOS,CGRP,p-Akt proteins in the anterior horn of spinal cord as well as iNOS and total NOS in serum of rats with brachial plexus root avulsion injury（BPRAI）.Methods:50 adult male SD rats were randomly divided into normal group,model group,low-dose,middle-dose and high-dose Puerarin Treatment group,with 10 rats in each group.The anterior and posterior roots of right spinal cord C₅-C₇ was avulsed in spinal canal of rats,and was cut at the same time to establish the BPRAI model.Puerarin was injected intraperitoneally into the low-dose,middle-dose and high-dose groups after operation at doses of 50 mg·kg^-1·d^-1,100 mg·kg^-1·d^-1 and 200 mg·kg^-1·d^-1,respectively.Normal and model groups were injected with saline of equal volume for4 weeks.Nissl staining was used to detect the survival rate of alpha-motorneurons（α-MNs）in the anterior horn of the spinal cord.Immunofluorescence was used to detect the expression of GFAP,p-Akt1/2/3 protein in the anterior horn of the spinal cord.Serum iNOS and total NOS were measured by colorimetry.Western blot was used to detect the expression of GFAP,iNOS and CGRP protein in the spinal cord on the injured side.Results:1.Nissl staining results showed that the survival rate ofα-MNs in the anterior horn of the spinal cord on the injured side in the model group was significantly lower than that in the normal group（P<0.01）;compared with the model group,the survival rate ofα-MNs was significantly higher in the middle-dose and high-dose puerarin therapy（P<0.01）.2.Immunofluorescence results showed that the expression of GFAP protein in the anterior horn of spinal cord on the injured side in the model group was higher than that in the normal group（P<0.01）;compared with the model group,the expression of GFAP protein in the middle-dose and high-dose Puerarin Treatment group was lower（P<0.01）;compared with the low-dose group,the expression of GFAP protein in the middle-dose and high-dose puerarin group decreased（P<0.05 or P<0.01）.Compared with the normal group,the glial cells in the anterior horn of spinal cord on the injured side of the model group expressed a large amount of p-Akt1/2/3（P<0.01）;compared with the model group,low-dose,middle-dose and high-dose of Puerarin could inhibit the expression of p-Akt1/2/3 in glial cells（P<0.05 or P<0.01）;compared with the low-dose group,high-dose puerarin could inhibit the expression of p-Akt1/2/3 in glial cells（P<0.05）.3.The results of serum biochemical test showed that the expressions of iNOS and total NOS in low-dose and middle-dose group were higher than those in model group（P<0.05 or P<0.01）;compared with the low-dose group,the total NOS expression in the high-dose group decreased（P<0.05）.4.Western blot test showed that the expression of iNOS protein in the spinal cord on the injured side of the high-dose group was significantly lower than that of the model group（P<0.05）;compared with the low-dose group,the expression of iNOS protein in the injured spinal cord decreased in the high-dose group（P<0.05）.Compared with the normal group,the expression of GFAP protein in the model group increased（P<0.05）;compared with the model group,the expression of GFAP protein in the low-dose,middle-dose and high-dose group decreased（P<0.05）.Compared with the normal group,the expression of CGRP protein in the model group decreased（P<0.05）;compared with the model group,the expression of CGRP protein in the high dose group increased（P<0.05）.Conclusion:Puerarin can improve the survival rate of MNs in the anterior horn of spinal cord after brachial plexus root avulsion.The mechanism may be related to its inhibition of astrocyte activation,iNOS and GFAP protein expression,and the promotion of CGRP protein expression,as well as the involvement of p-Akt signaling pathway.In addition,the therapeutic effect is dose-dependent,and the middle-dose and high-dose are the best.