Effect of astragaloside IV on improvement of spatial learning and memory abilities and its mechanism in vascular dementia rat models of chronic cerebral ischemia / 中华神经医学杂志

ABSTRACT

Objective:To investigate whether astragaloside (AST) IV can improve spatial learning and memory abilities by alleviating oxidative stress damage to the frontal cortex and hippocampus in vascular dementia (VD) rats induced by chronic cerebral ischemia.Methods:Totally, 72 adult male Wistar rats were randomly assigned to four groups sham-operated group ( n=12), model group ( n=20), AST-IV 10 mg group ( n=20), and AST-IV 20 mg group ( n=20); chronic cerebral ischemia-induced VD models in the later three groups were established by permanent bilateral common carotid artery occlusion (BCCAO); 3 h after BCCAO, these rats were administered with saline, 10 mg/kg AST-IV, or 20 mg/kg AST-IV once daily for a consecutive 90 d. Ninety-four d after modeling, spatial learning and memory abilities were assessed by Morris water maze; the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT), and malondialdehyde (MDA) levels were measured by enzyme linked immunosorbent assay (ELISA). The levels of lipid peroxidation and oxidative DNA damage were assessed by immunohistochemical staining for 4-hydroxynonenal (4-HNE) and 8-hydroxy20-deoxyguanosine (8-OhdG), respectively. Results:(1) On the 3 rd, 4 th and 5 th d of place navigation test, the escape latency in rats of the model group was significantly longer than that in the sham-operated group, and that in the AST-IV 20 mg group was significantly shorter than that in the model group ( P<0.05); spatial probe test showed that the time percentage of rats spending in platform region in the model group (20.3%±1.7%) was significantly smaller than that in the sham-oprated group (48.2%±3.6%), and that in the AST-IV 20 mg group (39.7%±3.2%) was significantly larger than that in the model group ( P<0.05). (2) As compared with those in the sham-operated group, the SOD, GSH-Px and CAT activities were statistically decreased while MDA level was significantly increased in the frontal cortex and hippocampal CA1 area of rats in the model group ( P<0.05); as compared with those in the model group, the SOD, GSH-Px and CAT activities were statistically increased while MDA level was significantly decreased in the frontal cortex and hippocampal CA1 area of rats in the AST-IV 20 mg group ( P<0.05). (3) As compared with those in the model group, the numbers of 4-HNE and 8-oHdG positive cells in the frontal cortex and hippocampal CA1 area of rats in the AST-IV 20 mg group were significantly smaller ( P<0.05). Conclusion:Intraperitoneal injection of high dose AST-IV can ameliorate oxidative damage in the frontal cortex and hippocampal CA1 area in chronic cerebral ischemia-induced VD models, and has the potential to reverse spatial learning damages and memory dysfunction.