Résumé
Objective: To explore the effects of chronic restraint stress (CRS) on the abilities of spatial learning and memory and the levels of excitatory amino acids in the hippocampal dentate gyrus (DG) in the old rats, and to investigate the neurochemical mechanism of CRS in affecting the spatial learning and memory abilities. Methods: Sixteen male SD rats (18 months old) were randomly divided into control group (n=8) and CRS group (n=8), and the rats in CRS group received CRS 2 h every day for 30 d. And then the spatial learning and memory abilities of rats were measured by Morris water maze (MWM) test, and the extracellular levels of excitatory amino acids including asparate (Asp) and glutamate (Glu) in the DG were simultaneously determined by in vivo microdialysis and HPLC. The levels of corticosterone (CORT) and epinephrine (EPI) in serum of the rats were examined by ELISA assay. Results: In CRS group, the escape latencies on the 2nd-4th days were significantly increased and the percentage of time spent in target quadrant on the 5th day was markedly decreased in MWM test compared with control group (P0. 05). Compared with control group, the levels of CORT and EPI in the serum of the rats in CRS group were significantly increased (P<0. 05). Conclusion: CRS impairs the spatial learning and memory abilities in the old rats, which may be related to the decrease of Asp level in the hippicampal DG of the rats.
Résumé
Objective:To explore the effects of chronic restraint stress (CRS) on the abilities of spatial learning and memory and the levels of excitatory amino acids in the hippocampal dentate gyrus (DG) in the old rats,and to investigate the neurochemical mechanism of CRS in affecting the spatial learning and memory abilities.Methods:Sixteen male SD rats (18 months old) were randomly divided into control group (n =8) and CRS group (n=8),and the rats in CRS group received CRS 2 h every day for 30 d.And then the spatial learning and memory abilities of rats were measured by Morris water maze (MWM) test,and the extracellular levels of excitatory amino acids including asparate (Asp) and glutamate (Glu) in the DG were simultaneously determined by in vivo microdialysis and HPLC.The levels of corticosterone (CORT) and epinephrine (EPI) in serum of the rats wereexamined by ELISA assay.Results:In CRS group,the escape latencies on the 2nd-4th days were significantly increased and the percentage of time spent in target quadrant on the 5th day was markedly decreased in MWM test compared with control group (P＜0.05).Compared with before training,the extracelluar level of Asp in the DG in control group was significantly increased on the 2nd day in MWM test;compared with control group,the extracelluar level of Asp in the DG in CRS group was significantly decreased on the 3rd day in MWM test (P＜0.05).Compared with before training,the Glu levels in the DG in MWM test in both control and CRS groups were markedly increased (P＜0.05),but there was no significant difference between two groups (P＞0.05).Compared with control group,the levels of CORT and EPI in the serum of the rats in CRS group were significantly increased (P＜0.05).Conclusion:CRS impairs the spatial learning and memory abilities in the old rats,which may be related to the decrease of Asp level in the hippicampal DG of the rats.
Résumé
Objective To observe the effects of kidney-tonifying therapy on spatial learning, memory abilities and ultrastructure of hippocampal dentate gyrus ( DG ) cells of kidney deficiency rats induced by sexual intemperance. Methods SD rats with low reproductive capacity were caused by continuously mating for 6 months, and then were randomly divided into 5 groups, namely model group, low- and high-dose of Liuwei Dihuang pills (LDP) groups (in the dosage of 4.8, 9.6 g·kg-1·d-1), low-and high-dose of Jingui Shenqi pills (JSP) group (in the dosage of 5.2, 10.4 g·kg-1·d-1), 8 rats in each group. Except the model group, the other groups were respectively given with the corresponding medication. SD rats aged 2 months served as the normal control group. After treatment for 30 continuous days, the learning and memory abilities of rats were examined by Morris Water Maze. The cell ultra structure of hippocampal dentate gyrus was observed by transmission electron microscopy. Results The results of the place navigation test of Morris water maze showed that the escape latency of rats was prolonged obviously in the model group compared with that of the normal control group (P<0.01), and the escape latency of rats in the medication groups was shorter than the kidney deficiency model group (P<0.05 or P<0.01). The results of spatial probe test showed that the residence time in the former hidden platform quadrant and its surrounding area was significantly shortened in the model group compared with that of the normal control group ( P<0.01) , but was prolonged after medication of high-dose JSP ( P<0.05 or P<0.01 compared with that of the model group). Under the electron microscope, the cell ultra structure lesions of hippocampal dentate gyrus were much relieved in the high-dose LDP group, and high-dose JSP group as compared with those of the model group. Conclusion ( 1) Long-term sexual intemperance can impair spatial learning and memory abilities and causes the cell ultra structure lesions of hippocampal dentate gyrus of rats. (2) The kidney-tonifying therapy can significantly alleviate the spatial learning and memory disturbance and the cell ultra structure lesions of hippocampal dentate gyrus induced by sexual intemperance. ( 3) There are not significant differences between the two kidney-tonifying therapies in improving spatial learning and relieving cell ultra structure lesions. The effect of JSP on improving spatial memory abilities is better than that of LDP.