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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.
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Objective: To observe the changes of dopamine (DA) levels in the hippocampal dentate gyrus (DG) region of the rats during the establishment and extinction process of active avoidance conditioned reflex, and to investigate the effect of D1 receptor in the active avoidance learning of the rats and its mechanism. Methods: A total of 24 male SD rats were randomly divided into non-training group, training group, control group and SCH group (n= 6). The rats in training group were trained for active avoidance whereas the rats in non-training group were only put into the shuttle box without training, and then the DA levels in extracellular fluid in DG region of the rats in two groups were measured. In control and SCH groups, the saline or SCH-23390 was injected into the DG region of the rats before the active avoidance training, and then the glutamate (Glu) levels and the field excitatory postsynaptic potential (fEPSP) amplitudes in extracellular fluid in DG region of the rats in two groups were examined. The rates of active avoidance of the rats were recorded by behavioral analysis system of the shuttle box. The levels of DA and Glu in DG region of the rats were measured by microdialysis and HPLC techniques, and the amplitude of fEPSP in DG region of the rats was examined by electrophysiological recording. Results: The DA level in DG region of the rats in training group was gradually increased during the establishment process and was gradually decreased during the extinction process of conditioned reflex; compared with the 1st day, the DA level in DG region of the rats on the 5th day was markedly increased (P0. 05). In control group, the rats reached the establishment criterion on the 5th day (active avoidance rate > 65%) and reached the criterion of extinction on the 7th day (active avoidance rate 0. 05). Compared with control group, the Glu level and fEPSP amplitude of the rats in SCH group on the 5th day were markedly decreased (P<0. 05). Conclusion: DA in hippocampal DG region of the rats can facilitate the active avoidance learning via activation of D1 receptors, and its mechanism is associated with the enhancement of Glu level and synaptic transmission efficiency.
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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.
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AIM:To explore the effect of Vaccinium vitis procyanidin on the growth of glioma cells .METH-ODS:Glioma C6 cells were cultured and divided into control and 10, 20 and 40μg/L Vaccinium vitis procyanidin groups . The influence of Vaccinium vitis procyanidin on the growth of C 6 cells was measured by MTT assay and the observation un-der inverted microscope .The apoptotic rate was detected by Annexin V/PI staining .The protein expression of Bcl-2 and Bax was determined by immunocytochemistry .The protein levels of Bcl-2, Bax and caspase-3 were also examined by West-ern blotting .RESULTS:The growth of C6 glioma cells was inhibited by Vaccinium vitis procyanidin at concentrations of 10, 20 and 40 μg/L.The growth was significantly inhibited in 40 μg/L Vaccinium vitis procyanidin group at 24 h and 48 h, and in 20 and 40 μg/L Vaccinium vitis procyanidin groups at 72 h (P<0.01).The density of the cells was decreased when the concentration of Vaccinium vitis procyanidin increased .The apoptotic rate was increased when the concentration of Vaccinium vitis procyanidin increased either .The expression of Bcl-2 was decreased and Bax was increased after 10, 20 and 40 μg/L Vaccinium vitis procyanidin treatments .The ratio of Bax/Bcl-2 was increased when the dose of Vaccinium vitis pro-cyanidin increased (P<0.05 or P<0.01).The expression of Bcl-2 was decreased (P<0.01), and Bax and caspase-3 were increased after 10, 20 and 40 μg/L Vaccinium vitis procyanidin treatments .The ratio of Bax/Bcl-2 was increased when the dose of Vaccinium vitis procyanidin increased (P<0.01).CONCLUSION:Vaccinium vitis procyanidin inhibits the growth of glioma cells by down-regulating Bcl-2 protein and up-regulating Bax protein to activate caspase-3, thus indu-cing apoptosis .
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Objective To study the influence of Rhizoma typhonii extract on the growth of glioma SHG-44 cells cultured invitro,and to explore the mechanism of the inhibitory effect of Rhizoma typhonii extract on the growth of glioma cells.Methods The SHG-44 cells were cultured and divided into blank control group and 8, 40, 200, 1 000μg·L-1 Rhizoma typhonii extract groups.The inhibitory effect of Rhizoma typhonii extract on the growth of glioma SHG-44 cells was measured by MTT assay. The secretion levels of Bax and caspase-3 proteins were examined by ELISA assay. The expression level of caspase-3 protein was examined by Western blotting method. Results Compared with blank control group, the inhibitory rates of the growth of SHG-44 cells in 200, 1 000μg·L-1 Rhizoma typhonii extract groups at 24 h,and 8,40,200,and 1 000μg·L-1 Rhizoma typhonii extract groups at 48 h were significantly increased (P<0.05 or P<0.01).The secretion levels of Bax and caspase-3 proteins in 40,200,and 1 000μg· L-1 Rhizoma typhonii extract groups at 48 h were increased compared with blank control group (P<0.05 or P<0.01 ). Compared with blank control group, the expression levels of caspase-3 protein in different doses of Rhizoma typhonii extract groups were increased significantly (P<0.01). Conclusion Rhizoma Typhonii extract can inhibit the growth of cells through up-regulating the expression of Bax protein,increasing the expression level of caspase-3 protein and activating apoptosis pathway.
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AIM:To explore the effect of component II of broccoli polypeptide on the apoptosis in glioma cells . METHODS:Human glioma SHG-44 cells were cultured and divided into control group and 3, 10, 30 and 100 mg/L com-ponent II of broccoli polypeptide groups .Cell viability was detected by MTT assay .The apoptotic rates were examined by Annexin V/PI staining.The morphological changes of the cells were observed under inverted microscope .The protein ex-pression of Bax and Bcl-2 was detected by immunocytochemistry and Western blotting .The protein level of caspase-3 was also examined by Western blotting .RESULTS:Treatment with component II of broccoli polypeptide for 24 h, 48 h or 72 h induced significant inhibition of viability of SHG-44 cells in a time-and dose-dependent manner .The results of Annexin V/PI staining showed that the apoptotic rates were increased in treatment groups in a dose -dependent manner .The density of glioma cells was decreased after treated with increasing concentrations of the drug , and the apoptotic bodies were ob-served under inverted microscope at 72 h.The results of immunocytochemistry and Western blotting showed that the expres-sion of Bax protein was increased but Bcl-2 protein expression was decreased , and the ratio of Bax/Bcl-2 was increased sig-nificantly compared with control group (P<0.05 or P<0.01).The level of caspase-3 protein was increased in 30 and 100 mg/L component II of broccoli polypeptide groups compared with control group (P<0.01).CONCLUSION:The compo-nent II of broccoli polypeptide increases the ratio of Bax /Bcl-2 and activates caspase-3 protein, thus inducing the apoptosis of glioma cells.