Effect Of Monosialoganglioside Pretreating On Bupivacaine Induced Neurotoxicity Caused By Endoplasmic Reticulum Stress In Rats

OBJECTIVE:This study was based on the establishment of spinal neurotoxicity model in rats underwent subarachnoid catheterization and intrathecal injection of bupivacaine,to investigate the effect of bupivacaine on endoplasmic reticulum stress induced by GRP78/PERK/eIF2a/ATF4 signaling pathway in rat spinal cord and therapeutic effect of intrathecal pretreatment of monosialoganglioside(GM-1)on bupivacaine-induced neurotoxicity in rat spinal cord.METHODS:180 healthy male Sprague-Dawley rats were randomly divided into 3 groups(n=60):saline group(group S),bupivacaine group(group B)and GM-1 group(group G).Rats in each group were treated with intrathecal catheter via L5?L6,and the rats with successful catheterization were screened out(the nerve injury was removed due to the trauma of the catheter operation;the tube was removed to the epidural space).Neurotoxicity model of local spinal anesthetics was established by intrathecal injection of 5%bupivacaine(0.12ul/g)in group B,group G was given intrathecal GM-1(30mg/kg)24 hours before the injection of bupivacaine and intrathecal injection the same amount of saline in group S.After intrathecal administration,rats were observed for Od(1.5 h),1d,3d,5d,7d and 14d(T1?T6),respectively.The tail flick latency test(TFL)was performed on rats at each time point(n=10)before and after the establishment of the model and converted to the percent maximum possible effect(%MPE),moreover,the motor function scores of hind limbs were evaluated with Basso,Beattie and Bresnahan score(BBB).The rats' lumbar enlargement was harvested,the histomorphology of spinal cord was observed by HE staining and the histopathological damage score was evaluated.Ultrastructural changes of spinal cord were observed under transmission electron microscopy(TEM)and apoptosis of spinal cord neurons was measured by TUNNEL method.The expression of GRP78,p-PERK,p-eIF2a and ATF4 protein and gene in spinal cord was detected by immunofluorescence,Western Blot and RT-PCR.RESULTS:Compared with group S,the pain threshold of tail fever,the apoptotic level of tissue,the expression of GRP78,p-PERK,p-eIF2a and ATF4 in spinal cord tissue in group B significantly increased and the BBB score significantly decreased(P<0.05)from T1 to T6.Compared with group B,the pain threshold of tail fever,the apoptotic level of tissue,the expression of GRP78,p-PERK,p-eIF2a and ATF4 in spinal cord tissue in group B significantly decreased and the BBB score significantly increased(P<0.05)from T5 to T6.Histomorphology and ultrastructural of spinal cord lumbar enlargement damage seriously in group B(T1?T6)and G(T1?T4)were observed,and the injury gradually recovered to normal in group G(T5?T6).CONCLUSIONS:Bupivacaine can induce neurotoxicity in rat spinal cord,which may be related to activation of GRP78/PERK/eIF2a/ATF4 signaling pathway induced by endoplasmic reticulum stress.Intrathecal pretreatment of GM-1 has certain therapeutic effect on spinal cord toxicity induced by bupivacaine spinal anesthesia in rats,and its mechanism may be related to the inhibition of endoplasmic reticulum stress GRP78/PERK/eIF2a/ATF4 signaling pathway.