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Rhizoma coptidis extract has a variety of pharmacological activities, including alleviating cognitive impairment in Alzheimer's disease(AD). The main mechanisms of its anti-AD activity include reducing the production of amyloid β(Aβ), inhibiting the phosphorylation of Tau protein, inhibiting cholinesterase, anti-inflammation, anti-oxidation, improving apoptosis, etc.This paper reviewed the anti-AD effect of Rhizoma coptidis extract and the specific mechanisms, aiming to provide a theoretical basis for relevant research and clinical practice.
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Objective:To explore the protective effects and mechanisms of L-carnitine (LCAR) on cognitive dysfunction in chronic cerebral hypoperfusion rats.Methods:Totally 90 SD male rats (SPF class) aged 3-4 months were divided into four groups according to random number talbe: sham operated control group (SHAM group, n=15), sham operated with L-carnitine treatment group (LCAR group, n=25), 2-vessel occlusion group (2VO group, n=25), and 2-vessel occlusion with L-carnitine treatment group (2VO+ LCAR group, n=25). The chronic cerebral hypoperfusion model was established by bilateral common carotid artery ligation, and the carotid arteries from SHAM group and LCAR group were only separated without ligation.L-carnitine was administered intraperitoneally (300 mg·kg -1·d -1) for 30 days after surgery in the LCAR and 2VO+ LCAR groups.After 30 days of L-carnitine intervention, Morris water maze was performed to test the spatial cognitive function of the rats, the ATP level of hippocampal tissue was detected by chemiluminescence, the mitochondrial structure and synaptic structure of hippocampal neurons were observed by transmission electron microscopy, the degree of mitochondrial damage was scored, the vesicle density was counted and measured, the level of N-methyl-D-aspartate receptor subunit 2A or 2B(NR2A/B) and postsynaptic density 95(PSD95) in hippocampal tissue were detected by Western blot.The expression and distribution levels of transcription factor cAMP response element-binding protein(CREB) in brain tissues were observed by immunofluorescence.SPSS 16.0 software was used for statistical analysis.The escape latency data of repeated learning training in Morris water maze was conducted by repetitive measurement ANOVA, while other data were adopted by one-way ANOVA, and Dunnett's t test was used for further pairwise comparison. Results:(1)Morris water maze results showed that the time and group interaction of escape latency was not significant among the 4 groups of rats ( F=1.4, P>0.05), but the time main effect and group main effect were significant( F=21.6, 15.2, both P<0.05). Morris water maze results showed that platform position learning from 3rd to 7th day, the escape latencies in 2VO group were longer than those in SHAM group and 2VO+ LCAR group (all P<0.05). The results of short-term memory showed that the escape latency in 2VO group was longer than those in SHAM group and 2VO+ LCAR group (all P<0.05). Meanwhile, the retention time and crossing times in the platform area of 2VO group were less than those in SHAM group and 2VO+ LCAR group (all P<0.05). (2) The absolute and relative levels of ATP in hippocampus showed that the difference among the 4 groups were statistically significant ( F=14.6, 13.2, both P<0.05). ATP level of hippocampus in 2VO group was lower than those in SHAM group and 2VO+ LCAR group (both P<0.05). Electron microscopic observation of mitochondrial morphology showed that the Flameng score of mitochondrial damage in the hippocampus of rats in 2VO group (2.82±0.17) was higher than those in SHAM group (0.25±0.07) and 2VO+ LCAR group (1.76±0.09) (both P<0.05). (3) The density of synaptic vesicles in the hippocampus of rats in 2VO group ((289.09±22.41)/μm 2)was lower than those in SHAM group ((497.49±28.89)/μm 2)and 2VO+ LCAR group ((401.23±45.09)/μm 2) (both P<0.01). Western blot results showed that the relative levels of synaptic proteins NR2A/B, PSD95 and CREB in 2VO group were lower than those in SHAM group and 2VO+ LCAR group (all P<0.05). Immunofluorescence results showed that the relative level of CREB expression in hippocampal subregions and cortex in 2VO group was lower than those in SHAM group and 2VO+ LCAR group (both P<0.01). Conclusion:L-carnitine can improve spatial learning and memory dysfunction in rats with chronic cerebral hypoperfusion, which are related with promoting ATP production and protecting mitochondrial morphology, and promoting synaptic vesicle synthesis and synaptic protein expression.
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Objective:To explore the roles and mechanisms of metformin in the improvement of cognitive dysfunction induced by chronic cerebral hypoperfusion in rats.Methods:Total 82 SD male rats (SPF grade) aged 3-4 months were randomly divided into four groups: sham operation control group (Con group, n=15), sham operation with metformin treatment group (Met group, n=20), 2-vessel occlusion group (2VO group, n=22), and 2-vessel occlusion with metformin administration group (2VO+ Met group, n=25). The chronic cerebral hypoperfusion model was established by bilateral common carotid artery ligation, and the carotid arteries of rats in Con group and Met group were only separated without ligation.After 2VO operation, rats in 2VO+ Met group and Met group were given metformin solution in drinking water at a dose of 100 mg/kg per day for 4 weeks.After 4-week continuous intervention with metformin, Morris water maze was performed to test the spatial cognitive function of the rats, in vivo electrophysiological technology was used to detect the long-term potential of the rats, and enzyme-linked immunosorbent assay(ELISA) was used to detect the concentrations of inflammatory factor tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β) and interleukin-6(IL-6) in the hippocampus.The density of dendritic spines of hippocampal neurons was observed by Golgi staining, and the synaptic structure of hippocampal neurons, especially the vesicle density, was observed by transmission electron microscopy.SPSS 16.0 software was used for statistical analysis.Repetitive measurement ANOVA was used for the escape latency data of 7 days repeated learning training in water maze.One-way ANOVA was used for the comparison of other data among multiple groups, and Dunnett's t test was used for further pairwise comparison. Results:Morris water maze results showed that during 7 days of learning training, the time and group interaction for escape latency was not significant in the 4 groups of rats ( F=0.93, P>0.05), but the time main effect ( F=25.90, P<0.05) and group main effect ( F=13.20, P<0.05) were significant.Morris water maze test showed that from the 3rd to 7th day, the escape latencies in 2VO group were significantly longer than those in Con group and 2VO+ Met group(all P<0.05). The short-term memory of rats was detected after 1 day of rest.The results showed that the escape latency in 2VO group was significantly longer than that in Con group and 2VO + Met group( P<0.01). The retention time and crossing times in the platform area of 2VO rats were less than those in Con group and 2VO + Met group ( P<0.01). Electrophysiological results showed that the relative field excitatory postsynaptic potential slope of 2VO group (1.29±0.09) was significantly lower than that in Con group (2.07±0.09) and 2VO + Met group (1.69±0.08)( P<0.01). ELISA results showed that TNF-α level in hippocampal tissue of 2VO group was significantly higher than that in Con group and 2VO+ Met group; IL-1β and IL-6 levels in hippocampal tissue of 2VO group were significantly higher than those in Con group and 2VO + Met group.Density of dendritic spines in hippocampal neurons of 2VO group was significantly lower than that in Con group and 2VO+ Met group.The density and proportion of immature dendritic spines in hippocampal neurons of 2VO group were significantly higher than those in Con group and 2VO + Met group.Synaptic vesicle density of neurons in CA1 area of hippocampus in 2VO group ((230.29±19.44) vescicles/μm 2) was significantly lower than that in the Con group ((414.52±13.17) vescicles/μm 2) and 2VO+ Met group ((313.19±12.42) vescicles/μm 2). Conclusion:Metformin can reduce neuroinflammation of hippocampus with chronic cerebral hypoperfusion and improve synaptic plasticity and cognitive dysfunction.It may have potential application value in the treatment of vascular cognitive dysfunction.
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Objective:To explore the role and mechanism of kidney brain protein (KIBRA) down-regulation in cognitive dysfunction caused by chronic cerebral hypoperfusion.Methods:Ninety male SPF grade Sprague Dawley (SD) rats were divided into four groups according to random number table: sham operation group ( n=15), chronic hypoperfusion group (2VO group, n=25), chronic hypoperfusion stereotaxic injection of AAV-KIBRA group (2VO+ AAV-KIBRA group, n=25), chronic hypoperfusion stereotaxic injection of AAV-Vector group (2VO+ AAV-vector group, n=25). Chronic cerebral hypoperfusion model was established by bilateral ligation of common carotid artery, and stereotactic injection of 2 μL AAV-KIBRA or AAV-vector was performed for 30 days.Morris water maze, in vitro electrophysiology, p21-activated kinase 3(PAK3) activity detection, Western blot, immunoprecipitation and Golgi staining were used to detect spatial learning and memory ability, long-term potentiation(LTP), KIBRA level expression, PAK3 activity changes and the distribution of dendritic spines.SPSS 16.0 statistical software was used for statistical data.One-way ANOVA was used to compare the differences between groups.LSD test was used to compare the significance of data differences between the two groups.Welch test was used for uneven variance. Results:After 1 month of chronic cerebral hypoperfusion, the level of KIBRA in the hippocampus of rats was detected by homogenate and Western blot, and it was found that the level of KIBRA in 2VO group was lower than that of sham group(73.49±4.12)% ( P<0.01). AAV-KIBRA injection in hippocampal CA1 region significantly up-regulated the level of KIBRA to (91.91±7.01)% over 2VO group ( P<0.01). Morris water maze test showed that the latency of the 2VO group(3rd-7th day trail data: (48.18±2.82)s, (43.45±2.27)s, (32.27±2.22)s, (26.55±2.37)s, (17.18±2.67)s) were significantly longer than those of the sham group((41.67±2.74)s, (32.58±2.57)s, (22.50±2.94)s, (16.91±2.39)s, (8.75±1.52)s) (all P<0.05), and the latencies of the 2VO+ AAV-KIBRA group 3rd-7th day trail data: (43.83±2.95)s, (35.25±2.15)s, (26.58±2.03)s, (19.92±2.17)s, (17.75±1.35)s) was significantly shorter than that of the 2VO group ((all P<0.01). The Morris water maze test with the platform removed showed that the latency of rats in the 2VO group to reach the platform region was significantly longer than that of the sham group, while the latency of rats in the 2VO+ AAV-KIBRA group to reach the platform region was significantly shorter than that in the 2VO group ( P<0.01). At the same time, the retention time and the crossing times in the platform region of 2VO group were less than those of the sham group ( P<0.01), but the retention time and the crossing times in the platform region of 2VO+ AAV-KIBRA group were significantly higher than those in the 2VO group ( P<0.01). The electrophysiological records of the brain slices showed that the relative excitatory postsynaptic field potential of 2VO group (1.43±7.43) was significantly lower than that of sham group (2.21±6.54) after high frequency stimulation, while the relative excitatory postsynaptic field potential of 2VO+ AAV-KIBRA group (1.90±8.15) was higher than that of 2VO group ( P<0.01). Immunoprecipitation in rat hippocampus revealed that PAK3 could be detected by Western blot assay when KIBRA was precipitated.The results showed that the relative enzyme activity of PAK3 in 2VO hippocampal tissue (0.64±0.04) was significantly lower than that in sham group (1.02±0.07), while the relative enzyme activity of PAK3 in 2VO+ AAV-KIBRA group (0.86±0.03) was significantly higher than that in 2VO group.Golgi staining showed that the density of dendritic spines in 2VO hippocampal neurons((6.85±0.43)/10 μm) was significantly lower than that in sham group((11.83±0.58)/10 μm), while the density of dendritic spines in 2VO+ AAV-KIBRA group((10.22±0.39)/10 μm) was significantly higher than that in 2VO group. Conclusion:The down-regulated of KIBRA after chronic cerebral hypoperfusion plays a key role in cognitive dysfunction and is also involved in the decrease of synaptic functional plasticity.The downregulation of KIBRA is involved in the structural plasticity of dendrites through the regulation of PAK3 activity.Therefore, KIBRA may be an important target for the prevention and treatment of cognitive function of chronic cerebral hypoperfusion.
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Objective:To explore the protective effect and mechanism of diammonium glycyrrhizinate (DAG) on cognitive dysfunction caused by chronic cerebral hypoperfusion.Methods:Seventy-three male Sprague Dawley rats in SPF degree were divided into sham group, chronic cerebral hypoperfusion group(2VO group), chronic cerebral hypoperfusion with DAG treatment group(2VO+ DAG group), and DAG treatment group(DAG group). During one-month chronic cerebral hypoperfusion models reproduced by the occlusion of bilateral common caroid artery, the rats were injected intraperitoneally with 2.917 mmol/L(20 mg·kg -1·d -1) DAG or saline for 15 days.Then the ability of learning and memory were tested by Morris water maze.Elisa, Western blot and Golgi staining were employed to test the spatial cognition, the changes of inflammatory factors, and inflammatory signal pathway molecules in hippocampus.The distribution of dendritic spines were observed and counted. Results:Morris water maze test showed that the learning latency of rats in 2VO group (3rd -7th day ) ((50.70±2.01)s, (43.53±3.22)s, (35.41±2.13)s, (25.26±1.85)s, (17.92±2.24)s) was significantly longer than that of sham group((40.28±1.94)s, (31.51±3.23)s, (24.7±2.25)s, (13.23±2.51)s, (9.42±1.91)s) (all P<0.01), while that of 2VO+ DAG group ((46.27±1.64)s, (38.54±1.51)s, (28.74±2.52)s, (19.73±2.13)s, (13.26±1.71)s) was significantly shorter than that of 2VO group ( P<0.05, P<0.01). After removing the platform to detect the memory of rats, the results showed that the latency of 2VO group (18.56±1.72)s) was significantly longer than that of sham operation group (11.25±2.11)s) ( P<0.01), while the time of 2VO+ DAG group was shorter than that of 2VO group (14.26±1.51)s ( P<0.01). In terms of the time of staying in the platform quadrant, the times of crossing through the platform area, the rats in the 2VO group were significantly less than those in the sham group ( P<0.01), while the rats in the 2VO+ DAG group were significantly more than those in the 2VO group ( P<0.01). Elisa data showed the levels of TNF-α, IL-1β and IL-6 in 2VO group (TNF-α: (27.42±1.91) pg/mg; IL-1β: (18.21±1.56)pg/mg; IL-6: (17.94±1.61)pg/mg)) were higher than those in sham group (TNF-α: (8.11±1.27)pg/mg; IL-1β: (6.78±1.12)pg/mg; IL-6: (5.67±0.91)pg/mg)) ( P<0.01), while the levels of three inflammatory factors in 2VO+ DAG group (TNF-α: (12.25±2.38)pg/mg; IL-1β: (9.93±0.96)pg/mg; IL-6: (8.72±0.65)pg/mg)) were significantly lower than those in 2VO group ( P<0.01). Western blotting data showed that the relative level of NF-κB in the nucleus of 2VO group (1.82±0.15) was significantly higher than that of sham group (1.00±0.09)( P<0.01), while that of 2VO+ DAG group (1.42±0.10) was significantly lower than that of 2VO group ( P<0.01). Golgi staining showed that the density of dendritic spines in CA1 area of hippocampus in 2VO group ((5.00±1.41)/10 μm) was significantly lower than that in sham group ((12.86±1.12)/10 μm) ( P<0.01), while that in 2VO+ DAG group was significantly higher than that in 2VO group ((9.23±1.65)/10 μm) ( P<0.01). Conclusion:DAG can effectively inhibit the neuroinflammatory response of hippocampus in chronic cerebral hypoperfusion, improve the damage of synaptic plasticity, and then improve the cognitive dysfunction caused by chronic hypoperfusion.DAG may be a potential effective drug for the treatment of chronic cerebral ischemia and vascular dementia.
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Objective To explore the roles of glycogen synthase kinase-3β (GSK-3β) in cognitive dysfunction and emotional alterations after rat's chronic cerebral ischemia.Methods 51 SD rats were randomly divided into sham group (sham group,n=17),chronic cerebral ischemia group (2VO group,n=17),chronic cerebral ischemia group + LiCl group (2VO + LiCl group,n=17),according to the table of random number.All groups were intraperitoneally injected with LiCl or saline on 3rd,7th,14th,21 st and 28th day,and then produced the chronic cerebral ischemia models.On the 28th day after model,the spatial learning and memory,fear memory,and anxiety emotion were detected.Results The Morris water maze test showed that 2VO group spent longer latent time searching and finding the platform than sham group (4th day P＜0.01,3rd,5th,6th,7th day P＜0.05).2VO+LiCl group spent shorter latent time than 2VO group (4th day P＜0.01,5th,6th,7th day P＜0.05).After removing the platform,2VO group spent longer time arriving the former location than sham group (P＜0.05).And 2VO+LiCl group spent dramatically different time compared to 2VO group (P＜0.01).Step-down test showed 2VO group spent shorter latent time than sham group (2VO group:(41.00±1.87)s,sham group:(44.55±2.77)s) (P＜0.05).2VO+ LiCl group spent dramatically longer latent time compared to 2VO group (2VO +LiCl group:(43.40± 1.35)s) (P＜ 0.05).2VO group made much more mistakes times than sham group (P＜0.05).2VO+LiCl group made dramatically less mistakes times compared to 2VO group (P＜0.05).The elevated plus maze test showed 2VO group had much less ratio of retention time in open arms (among total arms retention time) than sham group (2VO group:(0.23± 0.01),sham group:(0.25± 0.01)) (P＜ 0.01).2VO + LiCl group had much larger ratio than 2VO group (2VO + LiCl group:(0.24±0.01),P＜0.05).2VO group had much less ratio of entry times in open arms (among total arms entry times) than sham group (P＜0.01).2VO+LiC1 group had much larger ratio than 2VO group(P＜0.05).Conclusion Chronic cerebral ischemia can lead to deterioration of learning and memory,and anxiety emotion for rats.However,inhibition of GSK-3β can ameliorate these alterations.
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Objective To explore the effects of 4-phenylbutyric acid(PBA) on cognitive dysfunction after chronic cerebral hypoperfusion and underlying mechanisms.Methods 62 male Sprague Dawley rats in clean degree were divided into sham group(n=14),chronic cerebral ischemia group(bilateral carotid arteries occlusion,2VO group,n=24),and chronic cerebral ischemia with PBA treatment(2VO+PBA group,n=24).The chronic cerebral ischemia models were produced by the occlusion of bilateral common caroid artery for 1 month.During the hypoperfusion,the rats were injected intraperitoneally with 11.25 mg · ml-1 PBA(90 mg · kg-1 · d-1) or equal volume of saline once a day for 3 days followed by every other day for 27 days.Learning and memory abilities were tested by Morris water maze and novel object recognition test.The expression and distribution of NR2A in hippocampus were examined by Western blot and immunohistochemistry.Results Morris water maze test showed that the 2VO group had significantly longer latent time than sham group in searching platform (P＜0.01) (from 2nd day to 7th day latency time),and the 2VO+PBA group had dramatically shorter latent time than 2VO group (2nd,5th,6th,7th (P＜0.01),3rd(P＜0.05)).Then the rats' memory test showed that 2VO group spent markedly longer time than sham group to reach the location of the former platform(P＜0.01),but the 2VO+PBA group spent dramatically shorter latent time than 2VO group (P＜0.01).The novel object recognition test showed the exploration ratio and discrimination index of novel object in 2VO group were noticeably smaller than that in sham group (P＜0.01),but the exploration ratio and discrimination index of novel object in 2VO+PBA group were noticeably higher than that in 2VO group (P＜0.01).The Western blot data showed that the level of NR2A in 2VO group was significantly lower than that in sham group (P＜0.01),but the level of NR2A in 2VO+PBA group was significantly higher than that in 2VO group (P＜0.05).The level of NR2B in hippocampus of 2VO group had no significant difference with sham group and 2VO+PBA group (P＞0.05).Immunohistochemistry data was consistent with the data of Western blot for NR2A level and distribution.The ratio of p-CREB/total CREB in 2VO group(0.62±0.04) was remarkably lower than that in sham group(1.00±0.07),but the ratio of p-CREB/total CREB in 2VO+PBA group(0.97±0.07) was remarkably higher than that in 2VO group(P＜0.01).Conclusion NR2A reduction is associated with chronic cerebral hypoperfusion-induced cognitive impairment,which is rescued by the PBA treatment.It suggests that PBA may have a therapeutic effect on preventing chronic cerebral hypoperfusion-induced cognitive impairment.
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Objective To explore the correlationship between Cystatin C and the cognitive dysfunction, encephalatrophy and the cerebral perfusion in Alzheimer's disease ( AD ) patients, and to analyze the probable mechanisms of the Cystatin C level alterations. Methods For the 61 male and 55 female AD patients,the levels of Cystatin C,Urea,Cr andβ2?microglobulin were detected by biochemistry analysis.The hypocampus volume and Ev?ans index were measured by MRI imaging. The cerebral perfusion was evaluated by magnetic resonance perfusion imaging of arterial spin labeling technique and image processing. The cognitive level of AD patients was done by MMSE scale and MoCA scale. Results The Cystatin C levels in serum of male AD patients were dramatically dif?ferent from female AD patients(male:(0.95±0.20)mg/L,female:(1.32±0.41)mg/L)(P=0.04). For male AD patients,age and Cystatin C had a correlationship among the hypocampus volume((6157.14±355.58)mm3),Evans index(0.33±0.02),MMSE score(21.66±7.97),and MoCA score(21.96±6.19)(age:P=0.040,0.049,0.035, 0.039;Cystatin C:P=0.035,0.038,0.037,0.035),but for female only age((79.52±8.82)years) had a correla?tionship with the hypocampus volume((6319.53±377.74)mm3),Evans index(0.31±0.02),MMSE score(22.93± 6.22),and MoCA score(23.41±8.20)(P=0.044,0.045,0.047,0.046). For male AD patients,the marked correla?tionship was showed between Cystatin C and the index of cerebral perfusion(P=0.034),but for female patients, there's no correlationship(P=0.086) . Conclusion The Cystatin C level is distinctly different in male and female AD patients. The Cystatin C level in male AD patients maybe be an index to predict the degree of the cognitive dys?function and the level of cerebral perfusion.
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Objective To explore the roles and related mechanisms of Protein Phosphatase 2A(PP2A) in cognitive dysfunction after the chronic cerebral ischemia.Methods 70 male Sprague Dawley rats in clean degree were divided into sham group,chronic cerebral ischemia group (Bilateral carotid arteries occlusion,2VO),and chronic cerebral ischemia group with PP2A activation group(2VO+aPP2A).The rats were injected intraperitoneally with 1.88 μmol/ml sodium selenate(15 μmol · kg-1 · d-1) or equal volume of saline for 4 weeks.After one month,the chronic cerebral ischemia models were reproduced by the occlusion of bilateral common caroid artery.Then the abilities of learning and memory were tested by Morris water maze,electrophysiological indices were recorded to analyze the LTP changes,and destribution of synaptic vesicles was observed by electron microscope.Results Morris water maze test showed that the 2VO group had significantly longer latent time than sham group in searching platform(P＜0.05),and the 2VO+aPP2A group had dramatically shorter latent time (P＜0.01) than that of 2VO group.Then removing platform to test the rats memory,the data showed that 2VO group spent markedly longer time than sham group to reach the location of the former platform (sham group:(14.50±1.98)s ; 2VO group:(17.30±2.11) s) (P＜0.01),and the 2VO+aPP2A group((15.09± 1.45) s) spent dramatically shorter latent time(P＜0.05) than that of 2VO group.The electrophysiological data showed that 2VO group had the noticeably smaller field excitable postsynaptic potential slope (fEPSP) slope ratio between pre and post of the high frequency stimulations (Long-term potential,LTP) than sham group(sham group:1.69±0.27; 2VO group:2.02±0.137) (P＜0.01),and the 2VO+aPP2A group(1.86±0.19) had strikingly higher ratio than that of 2VO group(P＜0.01).The electromicroscope observation showed that presynaptic vesicles density of 2VO was remarkably lower than that of sham group (sham group:(4.51±0.29) /μm2 ; 2VO group:(2.02±0.14) /μm2) (P＜0.01),and presynaptic vesicles density of 2VO+aPP2A group((3.58±0.50) /μm2) was noticeably higher than that of 2VO group(P＜0.01).Conclusion Activating PP2A can prevent the cognitive dysfunction after chronic cerebral ischemia through regulating LTP and synaptic vesicle density.And PP2A is probably a potential target for preventing and treating the cognitive dysfunction after chronic cerebral ischemia.