Objective To investigate the changes of learning and memory function ,vascular endothelial growth factor (VEGF) and heme oxygenase‐1(HO‐1) expression in cerebral cortex and hippocampus of chronic ischemic vascular dementia rats . Methods Thirty‐six healthy SD rats were divided into the control group ,sham operation group and model group ,12 cases in each group .The chronic ischemic vascular dementia rat model was established by the permanent bilateral carotid artery occlusion The sham operation group received the same treatment to the model group except without bilateral carotid artery occlusion .The learning and memory abilities were tested by the Morris water maze experiment and climbing rope strength experiment at 1 ,4 ,8 ,12 weeks respectively .The expressions of VEGF and HO‐1 in rat cerebral cortex and hippocampus was determined by immunohistochemical SP technique .Results The escape latency time at 8 ,12 weeks in the model group was longer than that in the sham operation group and control group ,and the number of crossing the platform was less than that in the sham operation group and control group ,the differences were statistically significant (P<0 .05);the time of climbing at 1 -12 weeks had no statistical difference between the model group and the sham operation group and between the model group and the control group (P>0 .05) .The positive expression of HO‐1 and VEGF protein contents in the control group and sham operation group was less than that in the model group with sta‐tistical difference(P<0 .05) .Conclusion Chronic cerebral hypoperfusion has a permanent damage to the learning and memory abil‐ities in rats ,while has no influence on the motor function .VEGF and HO‐1 may play a protective role in chronic cerebral ischemia .

To study the chemical constituents from the bark of Myrica rubra, fourteen compounds were isolated from the methanolic extract using various chromatographic techniques, including silica gel, Sephadex LH-20 and preparative HPLC. Their structures were identified on the basis of chemical properties and spectroscopic data, as 3, 5-dimethoxy-4-hydroxymyricanol (1), myricanol (2), myricanone (3), myricanol 11-sulfate (4), myricitrin (5), quercetin (6), quercetin-3-rhamnoside (7), tamarixol (8), uvaol (9), ursolic acid (10), taraxerol (11), myricadiol (12), β-sitosterol (13) and β-daucosterol (14). Among them, compound 1 is a new compound, named as 3, 5-dimethoxy-4-hydroxymyricanol, compounds 8, 9 were isolated from the genus Myrica for the first time.