| Objective:To investigate the effects of Panax quinquefolium L.-Acorus tatarinowii on learning and memory ability and cognitive function,morphological structure of neurons and mitochondria in hippocampi,the expression of glucose transporter-4（GLUT-4）protein in the cell membrane of hippocampal neurons,the markers of energy generation and oxidative stress in tissue and mitochondria in hippocampi in diabetic rats,so as to further clarify the reasons of Panax quinquefolium L.-Acorus tatarinowii on prevention and treatment of diabetes-associated cognitive decline.Methods:115 healthy male Wistar rats of SPF grade were randomly divided into control group（n=16）and model group（n=99）,the rats in model group were intraperitoneally injected with streptozotocin 60 mg·kg-1 to replicate diabetic model.After 7 days of model replication,the fasting blood glucose level in rats were measured,and the fasting blood glucose level≥16.7 mmol·L-1 was regarded as the successful model replication.The diabetic rats with successful model replication were randomly divided into diabetic group（n=67）and metformin group（n=15）and Panax quinquefolium L.-Acorus tatarinowii group（n=15）.After 9 days of model replication,the rats in metformin group and Panax quinquefolium L.-Acorus tatarinowii group were given intragastric administration,meanwhile,the rats in control group and diabetic group were given the same dosage of distilled water once a day for 75 days continuously.After3,6,9 and 12 weeks of model replication,the fasting blood glucose level in rats in each group were measured.After 12 weeks of model replication,the Morris water maze and the novel object recognition tests were used to evaluate the learning and memory ability in rats in each group,and the rats in each group were screened for cognitive impairment and non-cognitive impairment by the Morris water maze performance.After the Morris water maze test,the glycated hemoglobin level in rats in each group were measured.The changes of morphological structure changes of neurons and mitochondria in hippocampi and the expression of GLUT-4protein in the cell membrane of hippocampal neurons in rats in each group were observed by the methods of HE staining and transmisson electron microscopy and immunohistochemistry.The levels of adenosine triphosphate（ATP）and superoxide dismutase（SOD）and malondialdehyde（MDA）in hippocampal tissue,and the levels of ATP and SOD in hippocampal mitochondria in rats in each group were measured.Results:97 diabetic rat models were successfully replicated,and the rate was 97.98%.Compared with control group,the fasting blood glucose level in rats in diabetic group were significantly increased at 3,6,9 and 12 weeks（P<0.01）,the glycated hemoglobin level in rats in diabetic group was significantly increased（P<0.05）.Compared with diabetic group,there were no significant differences in the levels of fasting blood glucose and glycated hemoglobin in rats in metformin group and Panax quinquefolium L.-Acorus tatarinowii group（P>0.05）.In the Morris water maze test,compared with control group,the escape latency in rats in diabetic group were significantly increased at the 8th,9th,10th times of orientation navigation and test period（P<0.05,P<0.01）.Compared with diabetic group,there were no significant differences in the escape latency in rats in metformin group and Panax quinquefolium L.-Acorus tatarinowii group（P>0.05）.After screening,the incidences of cognitive impairment in rats in diabetic group and metformin group and Panax quinquefolium L.-Acorus tatarinowii group were 40.00%and 28.57%and 20.00%,respectively,and there was no cognitive impairment in rats in control group.The rates of non-cognitive impairment in rats in control group and diabetic group and metformin group and Panax quinquefolium L.-Acorus tatarinowii group were 85.71%and 33.33%and 28.57%and 40.00%,respectively.There were no significant differences in the relative discrimination index of the novel object recognition test in rats in each group（P>0.05）.Compared with control group,the hippocampal neurons were loosely arranged or apoptotic,and the hippocampal mitochondria were swollen or pyknotic in rats in diabetes-associated cognitive decline group were severe.Compared with diabetes-associated cognitive decline group,the hippocampal neurons were loosely arranged or apoptotic,and the hippocampal mitochondria were swollen or pyknotic in rats in diabetes non-cognitive decline group and metformin group and Panax quinquefolium L.-Acorus tatarinowii group were alleviated.Compared with control group,the expression of GLUT-4 protein in the cell membrane of hippocampal neurons in rats in diabetes-associated cognitive decline group was significantly decreased（P<0.01）.Compared with diabetes-associated cognitive decline group,the expression of GLUT-4 protein in the cell membrane of hippocampal neurons in rats in metformin group was significantly increased（P<0.05）,there was no significant difference in the expression of GLUT-4 protein in the cell membrane of hippocampal neurons in rats in Panax quinquefolium L.-Acorus tatarinowii group（P>0.05）.There were no significant differences in the levels of ATP and SOD and MDA in hippocampal tissue,and the levels of ATP and SOD in hippocampal mitochondria in rats in each group（P>0.05）.Conclusion:In this experiment,after 12 weeks of model replication,the spatial learning and memory ability decreased and the cognitive impairment appeared in diabetic rats.Panax quinquefolium L.-Acorus tatarinowii may alleviate hippocampal neuronal damage by mitochondrial protection of hippocampi,thereby reducing the incidence of cognitive impairment,and improving the rate of non-cognitive impairment in diabetic rats. |
