| Objective:As the second largest dementia disease following Alzheimer's disease (AD), Vascular dementia (VD) is a kind of chronic, progressive and sustained mental dysfunction caused by various kinds of cerebral vascular disease. The clinical manifestations of VD in addition to symptoms and signs of damage location of nervous system, there are series of abnormal neuropsychological symptoms and spirit of the act.With the aging of the population, the incidence of VD increased year by year.VD is so far the only available prevention and treatment of dementia, which would have been reversible if give the early treatment. Therefore, to explore the pathogenesis and relevant factor of VD and seek the effective treatment measures, has important significance of social and medical.Currently considered that the chronic cerebral hypoperfusion is a major cause of VD.The pathogenesis of VD involves many aspects such as neurobiochemistrical, molecular immunity, and genetics. With increasing attention has been gave to the position of inflammatory mechanism in ischemic cerebrovascular disease, more and more data showed that the inflammatory reaction played a major role in secondary nerve injury after cerebral ischemia, and involved in the occurrence and development of VD.Inflammatory response begins with inflammatory cell adhesion, migration, infiltration, activation and inflammatory cytokine release.All kinds of factors involved in inflammation both have the respective roles, but also promote and adjust each other,forming a complex system of inflammatory response.As one of inflammatory cytokines which react earliest after cerebral ischemia, nuclear factor-КB (NF-κB) could code and control a variety of inflammatory cytokines, is considered one of the initiating mechanisms of the damage of vascular endothelial cell.With the help of adhesion molecules such as intercellular adhesion molecule -1 (ICAM-1), the inflammatory cells adhere to vascular endothelial cells,then enter the brain tissue and release various inflammatory factors furtherly.The reaction can lead to vasogenic and cell line-derived brain edema, increase secondary brain tissue damage after cerebrovascular,cause the neuron damage and apoptosis in brain tissue such as hippocampus, affect the overall cognitive function ultimately.As a kind of multi-target therapy drug that can act on multiple pathological aspects of brain ischemia, NBP has been widely used in clinical treatment of cerebral ischemia and VD,but the pharmacological mechanisms for treatment of VD is still exploring.The present study aims to observe the changes of NF-κB and ICAM-1 in hippocampus of mice through the establishment of VD model, then to explore the pharmacological mechanism of anti-inflammatory in improving the intelligence treatment of NBP.Methods: The study is made up of three sections. Section one was to establish VD models, Kunming mice were subjected for continuously three repeated times ischemia-reperfusion through the ligation of the bilateral common carotid arteries, accompanied by sham-operated group and treated group (NBP); the capabilies of learning and memory of mice were investigated by the stepdown test and water maze test, and the behaviors were observed after mice had been bred for 28 days. In section two, the mice's cerebral tissue were fast taken out, fixed up via perfusion of 4% paraformaldehyde solution, then we respectively observed the pathological change of hippocampus in each group after HE staining. In section three, the tissue were dyed by immunohistochemistry technique. Then the expressing change of NF-κB and ICAM-1 in hippocampus in each group was observed by light microscope, mean optical density (OD) of NF-κB and ICAM-1 positive cells were calculated, so that the differrent expression in each group was compared.Results: (1) Step-down test: The abilities to learning and memory in model group decreased evidently that was reflected by the prolongation of response period (P<0.05) and increase of the error times (P<0.05) during the learning phase, and by decrease of latent period (P<0.05) and increase of the error times (P<0.05) during the memory phase. However, the grades of learning and memory in treated group ameliorated apparently, compared with model group (P<0.05), nevertheless, no distinction was detected between treated group and sham-operated group (P>0.05). (2) Water maze test: The notably reduced grades of learning and memory in model group were shown as the prolongation of the whole course time of swimming and increase of the error times during both learning phase (P<0.05) and memory phase (P<0.05), whereas, the grades in treated group improved apparently, compared with model group (P<0.05), similarly, no difference was discovered between treated group and sham-operated group (P>0.05). (3) HE stainning in hippocampus: In sham-operated group, the hippocampal profile was clear,circinal and big nucleus, clear nucleolus. The many pyramidal cells ranged tightly, and dense nerve fibers were observed. However, in model group, there were decreased layers pyramidal cells that ranged loosely, their nucleus became small and dyed strongly ,the structure of nucleus was not clear, nerve fibers ranged unregularly. But the pathologic changes in treated group eased off. The number of normal neuron in each group per unit area in Sham-operated group, model group and treated group respectively were (102.46±13.16), (61.04±18.17) and (89.09±19.94).(4)Expression of NF-КB in hippocampus: The level of hippocampal CA1 area in sham-operated group was clear, NF-КB exist in the cytoplasm, occasionally weak positive expression within the nucleus. However the number of positive neurons increased significantly in model group, and the nucleus showed brown yellow or brown, loosely arranged, dyed dark. Compared with model group, the number of positive neurons decreased in treated group, arranged more compact, lighter staining. The mean optical density of positive cells in Sham-operated group, model group and treated group respectively were (0.0660±0.00436), (0.1533±0.01137), (0.0927±0.00379).Compared with the sham-operated group, the mean optical density of positive neurons increased significantly in model group (P<0.01), while the mean optical density value decreased significantly in the treated group compared with the model group(P<0.01).(5)Expression of ICAM-1 in hippocampus: The ICAM-1 positive cells could be seen occasionally in hippocampal CA1 area of the sham-operated group. the number of positive neurons that mainly had pale-brown stained cytoplasm increased significantly in the model group.And in the treated group the number of positive neurons decreased.The neurons arranged tightly and dyed lighter. The mean optical density of positive cells, in Sham-operated group, model group and treated group espectively were (0.0307±0.00416),(0.139±0.00917),(0.0833±0.0109). Compared with the sham-operated group, the mean optical density of ICAM-1 positive neurons increased significantly in model group(P<0.01), while the mean optical density of treated group decreased significantly compared with the model group (P<0.01).Conclusions: (1) The study has successfuly established VD model that imitated the clinical intelligent dysfunction of VD, as it was ascertained by step-down test and water maze test. (2) HE stainning in hippocampus show that pyramidal cells was damaged, in the mean time, the effect of NBP was demonstrated in the study. (3) It was confirmed that the increasing expression of NF-КB,ICAM-1 in hippocampus related to cognitive damage in VD, NBP could inhibit the inflammatory response in VD by inhibiting the expression of NF-КB and ICAM-1, thereby improved the clinical symptoms of VD.
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