Cerebrolysin Alleviates Vascular Cognition Impairment In Rats By Regulating The Expression Of CREB And Apoptosis-related Proteins In Hippocampus

Objective: With the dramatic increase in the proportion of elderly people worldwide,the morbidity of dementia increased year by year.Up to now,vascular dementia has became the second most common form of dementia after Alzhimer’s disease which has imposed a heavy burden to families and society.Due to the extremely pathogenesis of VD,there were failed to find successful drugs treatment of dementia.Cerebrolysin(CBL)is a porcine brain-derived peptide preparation that has pharmacodynamic properties similar to those of endogenous neurotrophic factors.Therefore,we think that CBL plays an important role in the maintenance of neuronal function and thus results in improved cognitive and behavioral performance.However,the effect and mechanism of the CBL is still lack of the reliable clinical evidence in vascular dementia induced by chronic hypoperfusion.The current study aim to observe rats’ the ability of learning and memory,hippocampal CA1 region morphology and the protein expressions of CREB,Bcl-2,Bax changes in vascular dementia model.To explore the intervention mechanism of method of modified CBL in treating vascular dementia model.Methods: Male Spague-Dawley rats aged 3 mouths were subjected to bilateral common carotid artery occlusion/two vessel occlusion(BCCAO/2VO)surgery.The animals were randomly divided into four groups after operation: sham+saline group,2VO+saline group,2VO+CBL(2.5ml/Kg)group and 2VO+CBL(5ml/Kg)group.The four groups were injected intraperitoneally after operation for 28 d,and then observed the changes of rats’ behavioral by Morris water maze experiment at day 29-34,including the place navigation test and the spatial probe test.After the behavioral test,HE staining was used to observe the pathological changes in the hippocampus by light microscopy.The protein expression of CREB,p-CREB,Bcl-2,Bax in hippocampal tissue were detected by Western blot.CREB was measured via immunohistochemical technique.Results:1 In the Morris water maze,all the animals showed a decreasing trend in the average escape latency with training.Compared with the sham+saline group,the rats in 2VO+saline group showed significant prolonged escape latencies during the 5-day training period.After the CBL treatment,however,these two groups exhibited shorter escape latencies compared with the 2VO+saline group,with statistic significance.In space exploration trial,with the platform removed,there were significant differences among four groups.In 2VO+saline group the percentage of swimming time in target quadrant significantly decreased.In CBL 2.5ml/Kg and 5ml/Kg groups,the deficits were significantly alleviated.2 HE staining observation: The pyramidal cells in the hippocampal CA1 areas of the sham+saline group were dense and hierarchy arrangement in neat.The morphology was integrity and clarity.The nuclei were rounder and larger,with clear nucleolus.Compared with the sham group,the 2VO+saline group pyramidal cells of structure were scattered and failure.Some pyramidal neurons turned karyopyknosis,with the nucleolus lost,cytoplasm pyknotic,hyperchromatic and cell count decreased significantly.While treatment with CBL partly alleviated the hippocampus damage exhibited in the 2VO+saline group.3 Protein and gene expression:3.1 Western blot results: Compared with the sham+saline group,the protein expression of p-CREB,Bcl-2 in 2VO+saline were downregulated with statistical significance(P<0.01).There was also a decline in CREB expression,without statistical significance.Bax were significantly increased(P<0.01).3.2 Western blot results: Compared with the 2VO+saline group,treatment with CBL downregulated Bax and upregulated p-CREB,Bcl-2 statistical significantly(P<0.05,respectively).3.3 Western blot results: There were no statistical significance between CBL 2.5ml/Kg and CBL 5ml/Kg.(P>0.05).4 The result of immunohistochemical: Microscopic findings showed that p-CREB immunoreation was negative in normal control group.Immunoreactiaction was brown and expressed in the cytoplasm and nucleus of neurons.The result of image analysis showed that the average optical density of p-CREB in 2VO group of hippocampus was significantly lower as compared with normal group and treatment group.Conclusions:1 By BCCAO to build the VD model was stable,valid and perfect animal model.2 Neurons loss and structural damage in hippocamal CA1 may be the morphological basis of VD model to learning and memory defect.3 CBL can effectively improve the cognitive functions of BCCAO rats and alleviate the pathological injuries of the hippocampal region.The mechanism may be closely related to the regulation of CREB and apoptosis-related protein.