| Objectives: Chronic cerebral hypoperfusion is a common pathological course of the developing of vascular dementia (VD), Alzheimer's disease (AD) and Bingswanger's disease, et al. Chronic low-perfusion behavior is a kind of pathological status of chronic ischemic nerve system injury with long term low perfusion brain that lower than threshold caused by hypertension and cerebral artery sclerosis. cerebral ischemia is a common pathological status, it accompanied with many cerebrovascular diseases, such as cerebral arteriosclerosis, Vascular dementia, Alzheimer's, Arteriovenous malformation. impairment is the main clinical situation in earlier pcriod of chronic cerebral ischemia, and then the permanent neural impairment. In our country, VD is one of major senile dementia, which not only impairs patients'physical and mental health badly, but also brings about a heavy load to the society and family. At present, the pathogenesis of VD has not been illustrated clearly, and dealed with effectively, either. Therefore, it's an important subject in medicine field to explore the pathogenesis of VD and make a reasonable therapeutic regimen. Chronic cerebral hypoperfusion may be one of the major causes for VD. Some studies show that cognitive function can be impaired under hypoperfusion and hypometabolism. And the disorder of free radical metabolism in brain may be one of the major possible mechanism, which results in impairment of cerebral texture and microvascular system. At the same time, free oxidate increases, SOD, its clearer, discreases, LPQ increases with its toxic output -MDA increasing relatively. MDA is a kind of toxic matter, the production of oxyradical induce the fracture of DNA-chain, accordingly activate the activity of PARP, Activated PARP take the important effection in ischemic brain injured, It stimulate the exhaust of NAD+, thereby, lead to the exhaust of ATP and cell death, People think peroxidatic reaction and free radical Mediated damage is caused by actived PARP, the more evidence indicate the PARP of over activation take the important effection in cellular oxidative damage.Butylphthalide is isolated in the celery seed, which possess the function of anti-cerebral ischemia, block up pathology element of brain injured that resulted by ischemia cerebrovascular disease.it increase the level of NO and PGI2 in Cerebral blood vessel endothelium by inducing the content of arachidonic acid, restrain the releasing of glutamic acid, cut down the density of intracellular Ca2+, suppress free radical raise the activity of antioxidase. But most studies have only focused on acute cerebral ischemia model at home and abroad, while the researches about its effect on chronic cerebral ischemia model have still lacked.Methods: 80 Sprague-Dawlay rats, 10 weeks old, 200~250g in weight, were randomly divided into sham group(n=20), saline group(n=20) Butylphthalide low dose group(n=20)and Butylphthalide large dose group(n=20). Saline group and Butylphthalide group were followed permanent occlusion of bilateral common carotid arteries (2-VO) accoding to de la Torre's method. Sham group was handled as Saline and dingbentai group except not ligating bilateral common carotid arteries. After 4 weeks following the operation, Butylphthalide low dose group were injected Butylphthalide (2mg·kg-1·d-1) through abdomen cavity for 4 weeks. Butylphthalide large dose group were injected Butylphthalide (6mg·kg-1·d-1) through abdomen cavity for 4 weeks. Saline group were injected isodose saline for 4 weeks too. Each group rats were executed at the corresponding time after water maze test. We dissected rat brain at ice disk, removed brainstem and cerebellum, rinsed in 0~4℃physiological saline(PS) to get rid of blood and then dried it by fiter-paper. At post-chiasm opticum 1mm and 4mm, we cut off the brain coronally and took the middle tissue which was hippocampus to fix, dewater, immerse wax, embedded and made into paraffin section. Morphological change was examined by HE staining. The expression of PARP was assayed by immunohistochemistry analysis. SOD activity and MDA content of anterior-chiasm opticum brain tissue were assayed.One-way analysis of variance was carried out with SPSS 13.0 statistics software, LSD-t test was used to compare the differences among the groups. P<0.05 meant statistical significance.Results: (1) The survival condition of each group: 9 died in the sham group. 8 rats died in the saline group. The death rates was 45% and 60% respectively. 12 rats died respectively in the Butylphthalide low dose group and Butylphthalide large dose groups. The death rates were 55%. All survival rats of each group were as study objects. (2) Water maze test: Learning and memory performances of rats decreased obviously in saline group, showing escape latency(EL) extended which were clearly higher than sham group (P<0.05). Compared with saline group. Learning and memory performances in Butylphthalide low dose group and Butylphthalide large dose groups improved significantly(P<0.05), compared with sham group. The performances in Butylphthalide low dose group and Butylphthalide large dose groups still decreased(P<0.05). compared with Butylphthalide low dose group. The performances in Butylphthalide large dose groups improved significantly (P<0.05). (3) HE stainning in hippocampus: The arrangement of pyramydal neurons at hippocampus CA1 in sham group was tight and in order, nucleus were large and round, and the chromatospherites were evident; In saline group, the arrangement of pyramydal neurons was loose and not in order, pyramydal neurons lacked and inflammatory cells infiltrated, cell bodies shrinked, karyopycnosis and cytoplast dyed densely; The arrangement of pyramidal neurons was better than saline group in Butylphthalide group, the phenomenon of karyopycnosis and inflammatory cells infiltrate was less. (4) The expression of PARP at hippocampal CA1 area: only few positive neurons were observed at hippocampal CA1 area in sham group; There were a few of positive neurons expressed in saline group which aligned loosely, cell bodys shrinked and karyopycnosis. The integrated optic density (IOD) of positive neurons was higher obviously than that in sham group(P<0.05). A great quantity of PARP positive neurons distributed at hippocampal CA1 area in the Butylphthalide low and large dose group. The positive substance located mainly in intracytoplasm, and nucleuses also expressed a little. The positive neurons ranged tightly, brown and yellow, the cell bodies were round or ellipse, and prominences were observed in some bodies. We discovered that the IOD of Butylphthalide low and large dose group increased significantly compared with sham group (P<0.01). Similarly, the positive neuron IOD of Butylphthalide low and large dose group was clearly decreased compared with saline group (p<0.01).(5)The results of SOD and MDA : Compared with sham group, SOD activity of forebrain tissue decreased in Butylphthalide low and large dose group, and MDA content increased(P<0.05). Compared with saline group, the SOD activity of Butylphthalide low and large dose group increased more, and MDA content decreased more (P>0.05). Compared with Butylphthalide low dose group, the SOD activity of Butylphthalide large dose group increased and MDA content decreased(P<0.05).Conclusions: (1) 2 veins occlusion animal model were adopted in the experiment. It caused cerebrovasculer hypoperfusion, which is similar to cerebrovasculer hypoperfusion of human. Water maze test verified that model rats existed learning and memory disorder, At the same time, the effect of Butylphthalide was proved in the study. (2) With immunohistochemistry, this study confirmed that the expression of PARP increased at hippocampus of rats under chronic cerebral hypoperfusion, which may participate the compensation and accomodation mechanism of chronic cerebral hypoperfusion. We adopted xanthine-oxydation and thio-barbituric acid to measure SOD activty and MDA content respectivly, and proved that SOD activity of forebrain decreased while MDA content increased after 2-VO. After Butylphthalide treatment the expression of PARP at hippocampus decreased obviously, SOD activty of forebrain strengthened clearly and MDA content decreased significantly. All of those illuminated that Butylphthalide could improve vascular cognitive impairment by multi-ways such as promoting PARP expression, inhibiting the activity of xanthine oxidase and hypoxanthine oxidase, lowering hydroxy radical concentration and so on.
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