| Background and Objective Alzheimer disease which is suffered by the elderly is a kind of disease in the central nervous system and develop gradually. But its etiopathogenisis is not clear. At present, AD has been the fourth leading cause of death in the developed country; with the advent of ageing society in our country and the increase of incidence rate of AD, the treatment and nursing care of AD sufferer will bring grave burden to the society. Rencenly, studys had indicated that AD has extremely close Relationship with ischemic cerebrovascular disease; the decrease of cerebral blood flow can aggravate the changes of cognitive impairment and pathology in the AD. It hint that vascular facts participate the development of AD. But so far systematic studys about cerebral ischemia intervention AD are lack and concrete pathogenesis of cerebral ischemia involvement or acceleration AD. Our study trys to investigate the function of learning and memory and expression of Aβ1-40 and bcl-2/bax in the cerebral hippocampus and cortex of rats and neuroprotective effect of puerarin on AD model after cerebral ischemia. So we may determine the relationship between cerebral ischemia and AD and provide a new idea with the diagnosis and prevention of AD.Methods 70 healthy male SD rats were devided randomly into 7 groups:AD group(10 rats); AD plus puerarin group (AD+Pue ,10 rats); cerebral ischemia group (CI,10 rats); cerebral ischemia plus puerarin group( CI+Pue ,10 rats); AD after ischemia group (AD+CI ,10 rats); AD after ischemia plus puerarin group (AD+CI+Pue ,10 rats); sham-operated groups(10 rats). AD model were induced by Aβ25-35 injection into the right amygdala ; CI model were made by left common carotid artery occlusion permanently and right common carotid artery repatency after transient occlusion ;AD+CI model were that cerebral ischemic operation were built after AD model succeeded on the 14th day. From the 14th to 21th day after surgery, groups of puerarin treatment received daily intraperitoneal injection of puerarin (80mg/kg), groups of puerarin nonintervention received daily intraperitoneal injection of 4.3%polyvinylpyrrolidone. Learning and memory ability in rats was detected through Y-maze on preoperation and on the 14th and 21th day after operation . On the 21th day , animals in each group are anaesthetized and perfused afterY-maze detection. HE staining was applied as a general observation of cell damage.The expression of Aβ1-40and bcl-2/bax in the brain of rats were determined by immunohistochemistry.Results1.The learning and memory abilities of rats in the Sham-operated groups were normal. Compared with Sham-operated group, the learning and memory ability of rats in the AD groups and cerebral ischemia groups and AD after cerebral ischemia groups were impaired (P<0.05); compared with AD groups and cerebral ischemia groups, The spatiallearning and memory impairment in the AD after cerebral ischemia groups aggravated(P<0.05). Puerarin significantly improved the spatial learning and memory impariment of rats.2.Immunostaining showd that there are few brown positive neuron of Aβ1-40 and bcl-2/bax in the Sham-operated groups. Compared with Sham-operated groups , The number of Aβ1-40 and bcl-2/bax positive cells significantly increased in the cortex and hippocampus of AD groups and cerebral ischemia groups and AD after cerebral ischemia groups ;the ratio of bax / bcl-2 rised (P<0.05); compared with AD groups and cerebral ischemia groups, The number of Aβ1-40 and bcl-2/bax positive cells obviously rocketed in the cortex and hippocampus of AD after cerebral ischemia groups ;the ratio of bax / bcl-2 went up (P<0.05). After treatment with Puerarin, the expression of Aβ1-40 and Bax protein downgraded and the expression of bcl-2 on the cortex and hippocampus of rats in each group except for sham-operated group upgrade.On the same time , the ratio of bax / bcl-2 reduced .Conclusions1.The spatial learning and memory imparement in AD model rats aggravated after cerebral ischemia. The mechanisms is closely related with nerve poison ofβ-amyloid peptide and the neuronal apoptosis .2.Puerarin can improve the learning and memory ability in AD model rats after cerebral ischemia may be involved with resistance nerve poison ofβ-amyloid peptide and inhibition neuronal apoptosis.
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