| Objective:Vascular dementia(VD)has already become a major publichealth problem, which is characterized by histopathological damage andprogressive intellectual decline produced by ischemic hypoxia or hemorrhagebrain lesion. VD is the second most common form of dementia afterAlzheimer’s disease and its incidence rate is increasing year by year. Theexact pathogenesis of VD is not very clear, but now it is generally acceptedthat brain ischemia-hypoxia is the main cause of VD. Ischemic hypoxia brainlesion will produce a large number of free radical, and an excess of freeradicals can cause lipid peroxidation, loss of protein function, DNA damageand so on. The hippocampus is an important structure for learning andmemory, and extremely sensitive to cerebral ischemia-hypoxia. Therefore,cerebral ischemia-hypoxia can easily lead to apoptosis of hippocampalneurons, thus the decline in learning and memory ability. Neuronal apoptosisis an autonomy and programmed cell death process regulated by gene, and isan important link of the cerebral ischemia-reperfusion injury. Bcl-2familymembers play a vital role in the gene regulation process of cell apoptosis.Bcl-2inhibits apoptosis, and bax promotes apoptosis. Both co-regulateapoptosis program, and are the most classical apoptosis regulation genes.Neuronal apoptosis after brain ischemia-hypoxia is related to oxidativestress. Probucol has the role of lipid-lowing, anti-oxidation, scavenging freeradicals. Several studies demonstrated that Probucol has strong antioxidanteffects. Now, the study concerning that probucol was used to treat vasculardementia is less. The study aimed to observe the effect of probucol againstvascular dementia rats on cognitive function and protein expression of bcl-2and bax in hippocampus, and explore its possible mechanism of action, thus toprovide experimental evidence for probucol clinical application. Methods: Healthy male SD rats were used to establish vascular dementiarat model by permanent occlusion of bilateral common carotid artery. The ratswere randomly divided into sham operated group, model group, probucolgroup, and there are12rats in each group. The rats in probucol group wereintragastrically given probucol500mg/kg/d. While the rats in sham operatedgroup and model group were given the same volume sodium carboxymethylcellulose. Morris water maze was used to evaluate learning and memoryability of rats in each group after8weeks administration. Positioningnavigation test was carried on to test escape latency time from the first day tothe fourth day, and the spatial exploration test was used to detect crossingplatform frequency at the fifth day. After ethology test, the level of bcl-2andbax in hippocampus were examined by western blot and immunohisto-chemical staining method.Results:1Influence of probucol on ethologe of VD rats1.1The results of escape latencyFrom the first day to the fourth day, escape latency time was tested toevaluate the learning ability of rats. The shorter escape latency time was, thestronger learning ability was. The escape latency time of rats was shortenedwith the increasing of the number of training days, indicating that training canenhance the learning ability, but there were differences in learning abilityamong the three groups. Within the first4days, escape latency time of rats inmodel group was significantly longer than that in sham operated group(P﹤0.05). There was no significant difference between probucol group and modelgroup at the first day(P﹥0.05), and from the second day to the fourth day, theescape latency time in probucol group was significantly shorter than that inmodel group(P﹤0.05). From the first day to the fourth day, there was nosignificant difference between probucol group and sham operated group(P﹥0.05).1.2The results of crossing platform frequencyCrossing platform frequency which represented memory ability was tested at the fifth day. The more crossing platform frequency was, the strongermemory ability was. The frequency of crossing platform in model group ratssignificantly decreased than that in sham operated group rats(1.75±1.14VS5.58±1.83,P﹤0.05). The frequency of crossing platform in probucolgroup rats significantly increased than that in model group rats (4.50±1.38VS1.75±1.14,P﹤0.05). The frequency of crossing platform was notsignificantly different between probucol group and sham operated group(4.50±1.38VS5.58±1.83,P﹥0.05).2Influence of probucol against vascular dementia rats on protein expressionof bcl-2and bax in hippocampus2.1The results of Western blot2.1.1The protein expression level of bcl-2in hippocampus of ratsThe protein expression level of bcl-2in hippocampus of model group ratswas significantly reduced than that of sham operated group rats(1.0783±0.1745VS1.4017±0.0880,P﹤0.05). The protein expression level of bcl-2inhippocampus of probucol group rats was significantly increased than that ofmodel group rats(1.5117±0.1734VS1.0783±0.1745,P﹤0.05). There was nosignificant difference in the protein expression level of bcl-2in rats’hippocampus between probucol group and sham operated group(1.5117±0.1734VS1.4017±0.0880,P﹥0.05).2.1.2The protein expression level of bax in hippocampus of ratsThe protein expression level of bax in hippocampus of model group ratswas significantly increased than that of sham operated group rats(0.4467±0.1133VS0.2050±0.0748,P﹤0.05). The protein expression level of bax inhippocampus of probucol group rats was significantly reduced than that ofmodel group rats(0.2300±0.0906VS0.4467±0.1133,P﹤0.05). The proteinexpression level of bax in rats’ hippocampus was not significantly differentbetween probucol group and sham operated group(0.2300±0.0906VS0.2050±0.0748,P﹥0.05).2.2The results of immunohistochemical staining2.2.1The number of bcl-2positive cells in hippocampal CA1region of rats The number of bcl-2positive cells in hippocampal CA1region of modelgroup rats significantly reduced than that of sham operated group rats(25.00±4.29VS35.00±3.03,P﹤0.05). The number of bcl-2positive cells inhippocampal CA1region of probucol group rats significantly increased thanthat of model group rats(39.17±4.12VS25.00±4.29,P﹤0.05). The numberof bcl-2positive cells in rats’ hippocampal CA1region was not significantlydifferent between probucol group and sham operated group(39.17±4.12VS35.00±3.03,P﹥0.05).2.2.2The number of bax positive cells in hippocampal CA1regionThe number of bax positive cells in hippocampal CA1region of modelgroup rats significantly increased than that of sham operated group rats(49.33±2.81VS25.33±3.83,P﹤0.05). The number of bax positive cells inhippocampal CA1region of probucol group rats significantly reduced thanthat of model group rats(27.00±4.65VS49.33±2.81,P﹤0.05). The numberof bax positive cells in rats’ hippocampal CA1region was not significantlydifferent between probucol group and sham operated group(27.00±4.65VS25.33±3.83,P﹥0.05).Conclusions:1The permanent occlusion of bilateral common carotid artery can be a goodsimulation of vascular dementia, and it is a deal VD animal model.2Abnormal expression of cell apoptotic factors exists in VD rats’hippocampus tissue, and this prompts that the cell apoptosis mechanismparticipates in the pathogenesis of VD.3Probucol can raise learning and memory ability of VD rats, and improvecognitive function of VD rats.4Probucol may inhibit neuronal apoptosis by increasing the proteinexpression of bcl-2and reducing the protein expression of bax inhippocampus of VD rats, thus play a role of neuron protection. |
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