| Objectives:Cerebral vascular disease (CVD) is one of three diseases that are severely harmful to the human. With the progress in therapy to CVD, the mortality due to CVD decreased, however, the mental and intelligent handicaps caused by CVD is increased. Vascular dementia(VD) which is seriously harming the body and the mentality of the elderly, is intelligent dysfunction syndrome, acquired and durative, resulted from all sorts CVD, as well as a heavy load to the society and the family, so the prevention and therapy to VD is increasingly attended. At present, the pathogenesis of VD can't be fully explained, and huperzine A which can ameliorate intelligent dysfunction, were widely treated in Alzheimer's disease, however, the pharmacological mechanism of treating VD were still in discussion. Hippocampus is considered as a important structure associated with learning and memory. Cholinergic neurons of medial septal nucleus and Broca diagonal band nucleus release acetylcholines(Ach) to hippocampus, which are main sources of cholinergic fiber in hippocampus, participate in the form of learning and memory. If cerebral tissue is suffered from ischemia and anoxia, the distribution and concentration of acetylcholinesterase(AchE) and choline acetyltransferase(CHAT) will be affected so that the concentration of Ach will change. The VD mice models were established in the experiment, the changes of AchE and CHAT in hippocampus were observed, then cholinergic pathogenesis of VD wouldl be in discussion, and the mechanism of huperzine A improving learning and memory function in VD would be discusssed. 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 group and drug group (Huperzine A); the capabilies of learning and memory of mice were investigated by the step-down 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, and were dyed by immunohistochemistry and in situ hybridization technique. Then we respectively observed the expressing change of CHAT and its mRNA in hippocampus in each group by light microscope, surface density value about CHAT and CHAT mRNA positive cells were calculated, so that the different expression in each group was compared. In section three, the cerebral tissue was rapidly taken out, the hippocampal tissue was regarded as a studied object throughrapid separation and preservation in low temperature, then the active change of hippocampal AchE in each group was observed respectively. 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<0.01) and increase of the error times (P<0.01) during the learning phase, and by decrease of latent period (P<0.01) and increase of the error times (P<0.01) during the memory phase. However, the grades of learning and memory in drug group ameliorated apparently, compared with model group (P<0.01), nevertheless, no distinction was detected between drug group and sham 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<0.01) and memory phase (P<0.01), whereas, the grades in drug group improved apparently, compared with model group (P<0.01), similarly, no difference was discovered between drug group and sham group (P>0.05). (3) thionine stainning in hippocampus: In sham group, the hippocampal profile was clear, there were 3 to 5 layers pyramidal cells, circinal and big nucleus, clear nucleolus, abundant Nissl body in cytoplasm were observed. The many pyramidal cells ranged tightly, and dense nerve fibers were observed. However, in mo... |
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