| Background:Vascular dementia(VD) refers to a cognitive impairment syndrome caused by cerebrovascular blood supply obstacles resulting from cerebrovascular diseases such as cerebral infarction, hypoperfusion and bleeding. VD is a kind of continous impairment of acquired mental retardation based on memory and cognitive impairment or accompanying language or visual spatial skills and emotional or personality disorder. At present, VD is the second major cause of presenile dementia besides Alzheimer's disease. With changes of the diet structure and social environmental factors and an increasing number of aged population, the incidence rate of cerebrovascular disease increased, of which ischemic cerebrovascular diseases account for more than 80%, in which 20% ~ 30% develop to vascular dementia. Currently VD lacks of effective treatment , mainly on prevention.Salidroside alpine has a significant protective effect on chronic neurodegenerative disease such as Alzheimer's disease (Alzheimer's disease, AD), Parkinson's disease (Parkinson's disease, PD), cerebral ischemia / hypoxia et al. Salidroside alpine effectively improves cerebral blood rheology and enhances energy metabolism at the level of organ ,and captures free radicals and changes central neurotransmitter and receptor function at the level of molecule , so that the internal environment of human disorders can be corrected, and blood can be smooth. As the human cells potential activator, salidroside alpine can stimulate the body's natural defense capabilities and change the slack status of organs. Based on MCAO model in rats, we can observe combined with water maze dynamically the effects of salidroside on rats'learning and memory capacity, and evaluate comprehensively the dynamic changes of cognitive impairment after cerebrovascular injury and salidrosid's effective intervention on cognitive impairment combined with morphology index and changes of peripheral blood acetylcholine level. By this research, it is expected to provide guidance reference on salidroside vascular dementia in the preventive protection and treatment.Methods:44 male SD rats were randomly divided into sham-operated control group, cerebral ischemia / reperfusion group, preoperative and postoperative treatment group. Intraperitoneal injection of Salidroside, 12mg/ml of each rat. Through the TTC, HE and Nissl staining, we can operate morphological observation, through the Morris water maze to assess spatial learning and memory ability in rats and determine the ACh content in peripheral blood in order to explore mechanisms.Results:1. MCAO model of cerebral ischemiaThe success rate of model is not high, its average success rate is 63.8 %, one of them occurred epileptic seizure symptoms, death mostly occurred within 24hs after ischemia. There is no difference among cerebral ischemia / reperfusion group , the preoperative treatment group and postoperative treatment group in neurology score. Before and after surgery, we monitored the weight of the rats, which decreased after 24h, 3d and weight picked up in the 7d, RSGS preoperative treatment group weighed 237.43±9.02 g in the 24h, significantly lower than the control group(P<0.05), which weighed 227.29±35.96 g in 3d. There was a significant difference compared with the control group and cerebral ischemia groups(P<0.05). It indicated RSGS plays a role in weight loss. Morphological observation showed that the middle cerebral artery suture mainly damage cortical and caudate putamen.2. Assessment of spatial learning and memory ability2.1 Positioning navigation test: through comparing incubation period of rat during 4 day's training to find the platform, we found that the incubation period in each group is similar in 1~3 d-trained rats and there was no significant difference. But in the forth day of training, incubation period of cerebral I/ R group is 37.69±12.95s, while in sham-operated control group it is 17.35±16.00s, there was a significant difference between the two groups(P<0.05). However, there were no significant differences among sham-operated control group, preoperative treatment group(34.5±19.27s), postoperative treatment group(20.27±6.58 s) . It indicates that cerebral I/ R group may exist cognitive impairment of spatial learning ability , while slidroside may improve the damage.2.2 Space exploration experiment: when the15th day of cerebralI/ R, the capacity of space exploration has no significant difference in each group; the 24th day of cerebralI/R, memory reproduction capacity has no significant differences in each group.3. Determination of ACh concentration in peripheral bloodWhen the 15th day of cerebralI/R, the cerebral ischemia/reperfusion rat peripheral blood ACh content increased to 194.22±17.48μg/100ml, compared with the control group it increased significantly(P<0.05), but when the 24d it reduces dramatically to 85.33±22.31μg/100ml, comparing with the control group it showed significant differences(P<0.001), suggesting that the level of ACh in peripheral blood exists some regular changes after long period of time's cerebral ischemia/reperfusion. When the 15 days, the preoperative treatment group significantly increased compared with control group and the cerebral ischemia group reaching 237.27±27.07μg/100 ml(P<0.01), 24d when the ACh content of preoperative treatment group is higher than the ischemic group which is 195.11±70.00μg/100 ml, nearly close to the level of the control group; the level of ACh in postoperative treatment group in the 15 d is similar to the control group, it's 177.18±30.82μg/100 ml, but significant higher than ischemic group(P<0.01), but in 24 d, the postoperative treatment group ACh levels decreased to 155.24±17.48μg/100 ml, but hasn't yet returned to the level of the control group(P<0.05), but significantly higher than cerebral ischemia group(P<0.01). These results suggest that cerebral ischemia exist changes of ACh content in the blood which increased slightly then decreased significantly, preoperative application of RSGS increased obviously ACh content . Conclusion:1. The late phase of MCAO cerebral ischemia/reperfusion model can imitate cognitive impairment of the vascular dementia .2. Pre-treatment and treatment of salidroside alpine can effectively improve cerebral ischemia/reperfusion injury.3. Salidroside alpine can enhance the space learning ability of animals, but the impact on spatial memory was not obvious.4. Salidroside alpine significantly affects the level of peripheral ACh.
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