Cerebroprotein Hydrolysate-Ⅰ Protects Cerebral Ischemia Reperfusion Injury By Inhibiting MEK/ERK1/2 Signaling Pathway In Rats

Objective: This experiment aims to investigate the neuroprotective effect and mechanism of cerebroprotein hydrolysate-Ⅰ(CH-Ⅰ)on cerebral ischemic reperfusion injury in rats.Methods: Total of 60 adult SPF male Sprague-Dawley(SD)rats,12 of which were randomly selected as sham group,and the other rats were used to built the middle cerebral artery occlusion/reperfusion(MCAO/R)models by suture-occluded method.The 36 successful models were randomly divided into 3 groups: model group,CH-Ⅰ treated group and cerebrolysin(CBL)positive drug group consisting of 12 rats in each group.The rats in CH-Ⅰ groups and CBL group were performed by intraperitoneal injection of CH-Ⅰ(20mg/kg)and CBL(20 mg/kg)respectively,and those in the model and sham groups were given the same amount normal solution at same times.After treatment,the neurobehavioral functional deficits of rats were evaluated by modified neurological severity scores(mNSS).Triphenyl tetrazolium chloride(TTC)staining was used to detect the cerebral infarction volume(CIV)of rats.HE staining and Nissl staining were used to observe the changes of nerve cells in the ischemic area of rats.The neuronal apoptosis was counted by TUNEL assay.IHC was used to detected the expressions of BDNF and pMEK1/2.The expressions of BDNF,pMEK1/2,pERK1/2 and pCREB were determined with Western blotting.Results: The rats in the sham group did not have neurobehavioral dysfunction and ischemic infarct lesions,but neurobehavioral dysfunction and ischemic infarction lesions were found in all rats after modeling.After treatment,the mNSS and CIV of rats were improved than those in the model group(P<0.05),while CH-Ⅰ group did not show significant difference compared with the positive drug CBL group(P>0.05).Neuronal structure and apoptotic staining showed that the denatured cell index(DCI)and apoptosis cell index(ACI)of rats in CH-Ⅰ and CBL groups were significantly decreased than those in the model group(P<0.01).Western blotting showed that the expressions of pMEK1/2,pERK1/2 and pCREB in rats were significantly increased while the expression of BDNF was decreased after modeling(P<0.05).After treatment,the expressions of pMEK1/2,pERK1/2 and pCREB in CH-Ⅰ group and CBL group were decreased(P<0.05),while the expression of BDNF was significantly increased(P<0.05)compared with the model group.IHC showed that the expressions of BDNF and pMEK1/2 were consistent with those in Western blotting.Conclurions: It is suggested that the CH-Ⅰ might play a neuroprotective role by inhibiting the expression of MEK-ERK-CREB and enhancing the expression of BDNF after cerebral ischemia/reperfuison injury,thus improving the neurobehavioral function of MCAO/R rats.