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SUMMARY: Hypoxic preconditioning is known to induce neuroprotection, but its effects and pathways in chronic brain pathology still unknown. The aim was to establish an involvement of a7 subunit of nicotinic acetylcholine receptors (a7nAchRs), and sirtuins of 1 (SIRT1) and 3 (SIRT3) types in the effects of hypoxic hypobaric preconditioning on brain damage in mice with chronic cerebral hypoperfusion caused by the left common carotid artery occlusion. The male C57/6j (C57, wild type) and a7nAchRs(-/-) mice were divided to six experimental groups (10 mice per group): sham-operated C57, C57 with chronic cerebral hypoperfusion, C57 with hypoxic hypobaric preconditioning and chronic cerebral hypoperfusion, sham-operated a7nAchRs(-/-) mice, a7nAchRs(-/-) with chronic cerebral hypoperfusion, a7nAchRs(-/-) with hypoxic hypobaric preconditioning and chronic cerebral hypoperfusion. For preconditioning, mice were exposed to hypoxia by "lifting" in barochamber to simulated altitude of 5600 m a.s.l. for 1 h/day on 3 consecutive days before surgical manipulation. Expressions of SIRT1, SIRT3 in brain tissue, and histopathological changes of the hippocampi were examined. It was shown that 8-week chronic hypoperfusion of the brain, caused by unilateral occlusion of the common carotid artery, was accompanied by injury to the neurons of the hippocampi of both hemispheres, which was more pronounced on the side of the occlusion. This damage, as well as the mechanisms of neuroprotection induced by hypoxic preconditioning, were maintained for at least 8 weeks by mechanisms mediated through a7nAChRs. Deficite of a7nAChRs was accompanied with reduction of neuronal damage caused CCH in 8 weeks, as well as preconditioning effects, and lead to compensatory activation of regulatory and protective mechanisms mediated by SIRT1, in normal conditions and in CCH. In wild-type (C57) mice, protective mechanisms in CCH were realized to a greater extent by increased expression of SIRT3 in both hemispheres of the brain.
Se sabe que el precondicionamiento hipóxico induce neuroprotección, pero aún se desconocen sus efectos y vías en la patología cerebral crónica. El objetivo fue establecer la participación de la subunidad a7 de los receptores nicotínicos de acetilcolina (a7nAchR) y las sirtuinas de tipo 1 (SIRT1) y 3 (SIRT3) en los efectos del precondicionamiento hipóxico hipobárico sobre el daño cerebral en ratones con hipoperfusión cerebral crónica causada por la oclusión de la arteria carótida común izquierda. Los ratones macho C57/6j (C57, tipo salvaje) y a7nAchRs(-/-) se dividieron en seis grupos experimentales (10 ratones por grupo): C57 con operación simulada, C57 con hipoperfusión cerebral crónica, C57 con precondicionamiento hipobárico hipóxico y crónica. hipoperfusión cerebral, ratones a7nAchRs(-/-) operados de forma simulada, a7nAchRs(-/-) con hipoperfusión cerebral crónica, a7nAchRs(-/-) con precondicionamiento hipobárico hipóxico e hipoperfusión cerebral crónica. Para el preacondicionamiento, los ratones fueron expuestos a hipoxia "levantándolos" en una cámara de barro a una altitud simulada de 5600 m s.n.m. durante 1 h/día durante 3 días consecutivos antes de la manipulación quirúrgica. Se examinaron las expresiones de SIRT1, SIRT3 en tejido cerebral y los cambios histopatológicos de los hipocampos. Se demostró que la hipoperfusión cerebral crónica de 8 semanas, causada por la oclusión unilateral de la arteria carótida común, se acompañaba de lesión de las neuronas del hipocampo de ambos hemisferios y que era más pronunciada en el lado de la oclusión. Este daño, así como los mecanismos de neuroprotección inducidos por el precondicionamiento hipóxico, se mantuvieron durante al menos 8 semanas mediante mecanismos mediados por a7nAChR. El déficit de a7nAChR se acompañó de una reducción del daño neuronal causado por CCH en 8 semanas, así como de efectos de precondicionamiento, y condujo a una activación compensatoria de mecanismos reguladores y protectores mediados por SIRT1, en condiciones normales y en CCH. En ratones de tipo salvaje (C57), los mecanismos de protección en CCH se realizaron en mayor medida mediante una mayor expresión de SIRT3 en ambos hemisfe- rios del cerebro.
Subject(s)
Animals , Mice , Brain Ischemia , Sirtuin 1/metabolism , Sirtuin 3/metabolism , alpha7 Nicotinic Acetylcholine Receptor/metabolism , Hypoxia , Cerebrovascular Circulation , Blotting, Western , Carotid StenosisABSTRACT
A visual and quantitative method of dynamically measuring microcirculatory blood flow in a tissue or organ in real time was developed using laser speckle contrast imaging technology.It has been used in numerous microcirculation detection domains because of its benefits of in vivo detection,real-time imaging,and ease of operation.Most animal models of chronic cerebral hypoperfusion involve decreasing blood flow to the brain from bilateral common carotid arteries,which can lead to a protracted deficit in cerebral blood supply.By monitoring and analyzing cortical cerebral blood flow,collateral circulation opening,and neurovascular coupling responses,laser speckle contrast imaging technology assesses the efficacy of modeling and the therapeutic effect of interventions in animal models of chronic cerebral hypoperfusion.This article summarizes the benefits and drawbacks of laser speckle contrast imaging in an animal model of chronic cerebral hypoperfusion to promote novel approaches to clinical care and academic study.
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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 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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@#Chronic cerebral hypoperfusion (CCH) is a potential important pathological factor leading to cognitive impairment in vascular dementia (VaD). The pathological mechanisms are complex and diverse,with cerebral white matter lesions being the main pathological feature,which is present throughout the entire progression of cognitive impairment caused by CCH. Dysfunction of the blood-brain barrier and neuroinflammatory responses caused by chronic cerebral hypoperfusion are important causes of cerebral white matter lesions. This article discusses the relationship between cerebral white matter lesions and VaD and the improvement of cerebral white matter lesions in VaD to slow down its development and progression,and explores the mechanism and therapeutic methods for VaD,aiming to find therapeutic targets of VaD to prevent its occurrence and improve symptoms.
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Cognitive impairment caused by chronic cerebral hypoperfusion (CCH) is associated with white matter injury (WMI), possibly through the alteration of autophagy. Here, the autophagy-lysosomal pathway (ALP) dysfunction in white matter (WM) and its relationship with cognitive impairment were investigated in rats subjected to two vessel occlusion (2VO). The results showed that cognitive impairment occurred by the 28th day after 2VO. Injury and autophagy activation of mature oligodendrocytes and neuronal axons sequentially occurred in WM by the 3rd day. By the 14th day, abnormal accumulation of autophagy substrate, lysosomal dysfunction, and the activation of mechanistic target of rapamycin (MTOR) pathway were observed in WM, paralleled with mature oligodendrocyte death. This indicates autophagy activation was followed by ALP dysfunction caused by autophagy inhibition or lysosomal dysfunction. To target the ALP dysfunction, enhanced autophagy by systemic rapamycin treatment or overexpression of Beclin1 (BECN1) in oligodendrocytes reduced mature oligodendrocyte death, and subsequently alleviated the WMI and cognitive impairment after CCH. These results reveal that early autophagy activation was followed by ALP dysfunction in WM after 2VO, which was associated with the aggravation of WMI and cognitive impairment. This study highlights that alleviating ALP dysfunction by enhancing oligodendrocyte autophagy has benefits for cognitive recovery after CCH.
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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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The glymphatic system plays a pivotal role in maintaining cerebral homeostasis. Chronic cerebral hypoperfusion, arising from small vessel disease or carotid stenosis, results in cerebrometabolic disturbances ultimately manifesting in white matter injury and cognitive dysfunction. However, whether the glymphatic system serves as a potential therapeutic target for white matter injury and cognitive decline during hypoperfusion remains unknown. Here, we established a mouse model of chronic cerebral hypoperfusion via bilateral common carotid artery stenosis. We found that the hypoperfusion model was associated with significant white matter injury and initial cognitive impairment in conjunction with impaired glymphatic system function. The glymphatic dysfunction was associated with altered cerebral perfusion and loss of aquaporin 4 polarization. Treatment of digoxin rescued changes in glymphatic transport, white matter structure, and cognitive function. Suppression of glymphatic functions by treatment with the AQP4 inhibitor TGN-020 abolished this protective effect of digoxin from hypoperfusion injury. Our research yields new insight into the relationship between hemodynamics, glymphatic transport, white matter injury, and cognitive changes after chronic cerebral hypoperfusion.
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Animals , Mice , Brain Ischemia , Carotid Stenosis/drug therapy , Cognitive Dysfunction/etiology , Digoxin , Disease Models, Animal , Mice, Inbred C57BL , White MatterABSTRACT
ObjectiveBased on the protective effect of Dengzhan Shengmai capsules （DZSM） on chronic cerebral hypoperfusion （CCH）， network pharmacology was employed to investigate the molecular mechanism. MethodCCH model was established by right common carotid artery ligation. The mice were divided into sham operation group， model group， ginaton group （48 mg·kg-1）， DZSM low- and high-dose groups （0.040 5， 0.162 g·kg-1）. The efficacy was evaluated by the Morris water maze test and open-field test. The underlying mechanism of DZSM for CCH was analyzed by network pharmacology and verified by molecular biology experiments. PubChem， GeneCards， Metascape and other databases were used for targets collection and enrichment analysis. Besides， the association of ingredients targets of DZSM with disease targets of CCH， core target network and chemical components-core targets-pathways network were constructed by STRING 11.0 and Cytoscape 3.7.1. ResultThe escape latency of CCH mice significantly shortened on the 3rd to 5th day after DZSM low-dose treatment， the crossing times， time spent in the target quadrant， movement distance and distance in the central region of CCH mice significantly increased after DZSM low-dose and high-dose treatment. The results of network pharmacology indicated that DZSM might play a key role by regulating inflammatory response， phosphatidylinositol 3-kinase/protein kinase B （PI3K/Akt） signaling pathway， cytokine-cytokine receptor interaction， tumor necrosis factor （TNF） signaling pathway， blood circulation， angiogenesis， extracellular matrix and other related biological processes and pathways， and acting as targets such as interleukin-6 （IL-6）， TNF， insulin-like growth factor 1 （IGF1）， vascular endothelial growth factor A （VEGFA）， epidermal growth factor （EGF）. The results of biological experiments showed that DZSM could reduce the expression of IL-6 in brain tissue of CCH mice. ConclusionDZSM provides a protective effect during CCH， and its multi-component， multi-pathway， multi-target mechanism is also revealed， which provides a basis for further study of the mechanism.
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Objective:To investigate the protective effect of Naoxin'an capsule （NC） against glial cell activation and inflammatory damage in brain of rats with chronic cerebral hypoperfusion-induced vascular cognitive impairment （VCI）. Method:One hundred and fifty rats were randomly divided into a sham operation group （<italic>n</italic>=20） and a modeling group （<italic>n</italic>=130）. Following the modeling with the two vessels occlusion （2-VO） technique， 87 successfully modeled rats were randomly divided into the model group， positive drug group （aricept， 0.5 mg·kg<sup>-1</sup>）， and low-， medium-， and high-dose （0.18， 0.36， 0.72 g·kg<sup>-1</sup>） NC groups， with 17-18 rats in each group. After intragastric administration of NC for eight weeks， the Morris water maze test and passive avoidance test were conducted to detect the effects of NC on learning and memory ability of VCI rats. Changes in neuronal structure of rat hippocampal CA1 area were observed by hematoxylin-eosin （HE） staining， and the neuronal apoptosis in hippocampus by terminal deoxynucleotidyl transferase （TdT）-mediated dUTP nick end labeling （TUNEL） staining. Western blot assay was used to detect the expression levels of glial fibrillary acidic protein （GFAP）， ionized calcium-binding adapter molecule 1 （Iba-1）， phosphorylated p38 mitogen-activated protein kinase （p38 MAPK）， and phosphorylated nuclear factor <italic>κ</italic>B （NF-<italic>κ</italic>B）， followed by the measurement of interleukin-1<italic>β</italic> （IL-1<italic>β</italic>） and tumor necrosis factor-<italic>α</italic> （TNF-<italic>α</italic>） in the brain by enzyme-linked immunosorbent assay （ELISA）. Result:Compared with the sham operation group， the model group displayed obviously decreased spatial learning and memory ability and memory retention ability （<italic>P</italic><0.05， <italic>P</italic><0.01）， neuronal damage in hippocampal CA1 area， enhanced neuronal apoptosis （<italic>P</italic><0.01）， up-regulated GFAP and Iba-1 （<italic>P</italic><0.01）， elevated phosphorylation of p38 MAPK and NF-<italic>κ</italic>B （<italic>P</italic><0.01）， and increased IL-1<italic>β</italic> and TNF-<italic>α</italic> （<italic>P</italic><0.01）. Compared with the model group， NC at each dose significantly improved the spatial learning and memory ability and memory retention ability of VCI rats （<italic>P</italic><0.05， <italic>P</italic><0.01）， ameliorated the neuronal damage in hippocampus CA1 area， reduced the apoptosis rate of nerve cells （<italic>P</italic><0.05， <italic>P</italic><0.01）， down-regulated the expression of GFAP and Iba-1 （<italic>P</italic><0.01）， decreased the phosphorylation levels of p38 MAPK and NF-<italic>κ</italic>B （<italic>P</italic><0.05， <italic>P</italic><0.01）， and lowered TNF-<italic>α</italic> and IL-1<italic>β</italic> levels （<italic>P</italic><0.01）. Conclusion:NC alleviates the inflammatory damage of the central nervous system caused by activated p38 MAPK and NF-<italic>κ</italic>B and improves chronic cerebral hypoperfusion-induced VCI in rats by inhibiting the activation of microglia and astrocytes.
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Objective:To investigate the effect of GluA2-3Y which is an inhibitor of AMPA(α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid) receptor internalization on cognitive function and hippocampal postsynaptic protein expression in rats with chronic cerebral hypoperfusion.Methods:Forty-eight adult male SD rats were randomly divided into Sham group, 2VO group, high-dose GluA2-3Y group and low-dose GluA2-3Y group according to random number table, with 12 rats in each group.The chronic cerebral hypoperfusion model of rat was established by two vessel occlusion (2VO) while the Sham operation was performed in rats of Sham group.The rats in high dose GluA2-3Y group and low dose GluA2-3Y group were intraperitoneal injected with 3 μmol/kg and 0.03 μmol/kg GluA2-3Y respectively once a day for 2 weeks. Rats in 2VO group and Sham group were intraperitoneally injected with control peptide. Morris water maze test and new object recognition test were performed to evaluate the learning and memory ability of rats, and Western blot was used to evaluate the expression of Akt1、GSK3β、p-GSK3β、GluA2 and PSD-95 in rat hippocampus. The expressions of GluA2 and PSD-95 in rat hippocampus were evaluated by immunofluorescence. SPSS 23.0 software was used for data analysis. The comparison between multiple groups was analyzed by one-way ANOVA and repeated measurement ANOVA was used to analyze Morris water maze results. And independent-samples t-test was used for pairwise comparisons. Results:(1)In Morris water maze trials, the results of repeated measurement ANOVA showed that the interaction between group and time of escape latency of rats in each group was not significant ( F=0.79, P>0.05), and the group main effect and time main effect were significant ( F=24.44, 40.42, both P<0.05). On the 5th day of navigation trials, the escape latency of rats in 2VO group was longer than that in sham group ( t=5.87, P<0.05). The escape latency of rats in low dose GluA2-3Y group and high dose GluA2-3Y group were significantly shorter than that in 2VO group ( t=2.20, 3.41, both P<0.05), but there was no significant difference between low dose GluA2-3Y group and high dose GluA2-3Y group ( t=1.37, P>0.05). The target quadrant residence time and resolution coefficient ((14.57±1.40)s, (0.15±0.10)) in 2VO group were significantly lower than those in Sham group ((23.71±2.57)s, (0.40±0.06)) ( t=3.23, 2.24, both P<0.05), while the target quadrant residence time in high dose GluA2-3Y group ((20.19±1.53)s) and low dose GluA2-3Y group ((20.31±2.06)s) were longer than that in 2VO group( t=2.71, 2.35, both P<0.05). The discrimination coefficients in high dose GluA2-3Y group (0.47±0.10) and low dose GluA2-3Y group (0.59±0.06) were higher than that of 2VO group ( t=2.21, 3.94, both P<0.05). (2)The Western blot results showed that the expression of PSD-95 and GluA2 in hippocampus of rats in 2VO group were significantly lower than those in Sham group ( t=2.31, 2.20, both P<0.05), and the expression of PSD-95 in high dose GluA2-3Y group (1.026±0.056) was significantly higher than that in 2VO group ((0.760±0.061), t=2.49, P<0.05), while there was no significant difference between low-dose GluA2-3Y group and 2VO group( t=0.96, P>0.05). The expression of GluA2 in low-dose GluA2-3Y group was higher than that in 2VO Group ((1.130±0.087), (0.766±0.080), t=2.37, P<0.05), but there was no significant difference between high-dose GluA2-3Y group and 2VO group( t=1.06, P>0.05). (3) Immunofluorescence showed that compared with Sham group, the expression of PSD-95 and GluA2 in 2VO group decreased ( t=4.23, 2.57, P<0.05). Compared with 2VO group, the expression of PSD-95 and GluA2 in high dose GluA2-3Y group and low dose GluA2-3Y group increased significantly, and the differences were statistically significant (PSD-95: (7.757±0.578), (12.057±0.578), t=3.14, 6.96, both P<0.05; (9.721±0.950), (16.610±0.950), t=4.56, 9.34, both P<0.05). (4) The results of Western blot showed that the expression GSK3β in hippocampus of rats in each group were not statistically different( F=2.03, P>0.05). There were significant differences in the expression of Akt1, p-GSK3β and the percentage of p-GSK3β/GSK3β in hippocampus of rats in each group ( F=8.30, 4.76, 3.57, all P<0.05). Compared with Sham group, the levels of Akt1, p-GSK3β and the percentage of p-GSK3β/GSK3β in 2VO group were significantly lower ( t=3.00, 2.81, 3.17, all P<0.05). Compared with 2VO group, the levels of Akt1, p-GSK3β and p-GSK3β/GSK3β percentage in low dose GluA2-3Y group and high-dose GluA2-3Y group were significantly higher (Akt1: t=2.05, 5.20, both P<0.05; p-GSK3β: t=2.49, 4.15, both P<0.05; p-GSK3β/GSK3β percentage: t=2.30, 2.97, both P<0.05). Conclusion:GluA2-3Y, an AMPA receptor internalization inhibitor, can alleviate the cognitive impairment in rats with chronic cerebral hypoperfusion, which may be related to the increased expression of Akt1, p-GSK3β and postsynaptic proteins.
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BACKGROUND: Previous studies have found that chronic cerebral hypoperfusion can cause changes in the intestinal mucosal barrier in rats, and Occludin and Claudin are important components of the intestinal mucosal barrier.OBJECTIVE: To explore the effect of chronic cerebral hypoperfusion on the ileum mucosal barrier. METHODS: Twenty male Sprague-Dawley rats were randomly divided into sham operation (sham) group and chronic cerebral hypoperfusion model group. Animal model of chronic cerebral hypoperfusion was built by permanent bilateral common carotid artery ligation. The bilateral common carotid arteries of the sham group were isolated without ligation. The animals were killed at 4 weeks after operation, and their ileums were isolated for morphological observation and pathological scoring using hematoxylin-eosin staining. Apoptosis in the ileum cells was detected using TUNEL. Western blot was used to detect the expression of Claudin-2 and Occludin. immunohistochemical staining was used to detect the expression of Occludin. The study protocol was approved by the Animal Experiment Ethics Committee of General Hospital of Western Theater Command. RESULTS AND CONCLUSION: Compared with the sham group, hematoxylin-eosin staining showed that the ileum in the model group did not develop obvious injury with no higher pathological scores (P > 0.05). Western blot results indicated that compared with the sham group, the expression of claudin-2 was increased in the ileum tissue of the rats with chronic cerebral hypoperfusion, while the expression of Occludin was decreased (P < 0.05). TUNEL fluorescence staining showed that the apoptotic rate in the model group was significantly increased compared with the sham group (P < 0.05). Immunohistochemical results showed that the expression of Occludin in the ileum tissue of the chronic cerebral hypoperfusion group was significantly reduced (P < 0.05). These findings indicate that chronic cerebral hypoperfusion may damage the intestinal mucosal barrier by downregulating Occludin expression and upregulating Claudin-2 expression.
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BACKGROUND: Chronic cerebral hypoperfusion is significantly associated with cognitive decline. Our previous studies have found that mitochondrial aging, increased silent synapses and α-synuclein are important pathological changes of chronic cerebral hypoperfusion. Simvastatin is a traditional lipid regulation agent that can traverse the blood brain barrier, and exerts anti-atherosclerosis, anti-thrombosis and anti-inflammatory effects to improve cognitive function. OBJECTIVE: To observe the effect of continuous oral simvastatin for 3 months on cognitive function of chronic cerebral hypoperfusion male Sprague-Dawley rats, and explore the clinical significance of simvastatin in preventing and treating vascular cognitive impairment and dementia. METHODS: Sprague-Dawley rats were randomly divided into model group, sham group, solvent group and simvastatin group. In the model group, rats were subjected to bilateral common carotid artery occlusion. In the sham group, the bilateral common carotid arteries were not ligated. In the solvent group, the model rats were intragastrically treated with 0.5% carboxymethyl cellulose sodium. In the simvastatin group, the model rats were intragastrically treated with simvastatin suspension. Interventions in each group lasted for 3 months. Behavioral tests were then used to evaluate the learning and memory ability of rats in each group. The expressions of synaptophysin and post-synaptic density 95, key proteins of presynaptic and postsynaptic membrane, were detected by western blot. Ethical approval was obtained from the Animal Experimental Ethics Committee of the General Hospital of Western Theater Command with approval No. 2019ky79. RESULTS AND CONCLUSION: Compared with the sham group, the learning and memory functions of the rats in the model group were significantly impaired. In the open-field test, the moving distance within 5 minutes was significantly reduced in the model group compared with the sham group (P < 0.05), suggesting that autonomous exploration behavior was impaired. In the place navigation test, escape latency was significantly shortened in the model group, implicating the reference memory was damaged. In the spatial probe test, the frequency of passing through the platform and the time for passing through target quadrant were reduced, indicating that the space exploration ability was reduced. In the simvastatin group, however, these indexes were all improved. Western blot results showed that the protein expression of synaptophysin and post-synaptic density 95 decreased significantly in the model group (P < 0.05), but increased in the simvastatin group as compared with the solvent group. Therefore, chronic cerebral hypoperfusion can significantly impair learning and memory function and reduce cognitive level in rats. Continuous oral simvastatin for 3 months can improve cognitive function in chronic cerebral hypoperfusion rats, which indicates that simvastatin may be used as an adjunctive drug to improve the prognosis of patients with vascular cognitive impairment and dementia.
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Ginkgo biloba and Panax notoginseng are both herb medicines for cerebrovascular disease, and play an active role in treating ischemic cerebrovascular disease(ICVD). Their mechanisms of action include antioxidant stress, nerve protection, vascular protection. According to the comparative study of literatures, G. biloba has a certain protective effect from the early stage of free radical formation throughout the whole process of causing cell inflammation and apoptosis in antioxidant stress; while P. notoginseng has mainly anti-inflammatory, anti-apoptosis effects. In the nerve protection and repair of nerve damage caused by glutamate, both could promote neurogenesis, repair damaged axons and protect nerve cells. In addition, G. biloba could also relieve neurotoxicity caused by glutamate damage, while P. notoginseng have a unique effect in repairing blood-brain barrier(BBB) and blood vessel regeneration. In clinic, they are used as auxiliary drugs in combination with thrombolytic therapy, and play curative effects in alleviating inflammation, eliminating edema, improving the cure rate and the prognosis. For cerebral diseases caused by chronic cerebral hypoperfusion, G. biloba could reduce inflammation and improve cognition. In addition, G. biloba could protect neurocyte by adjusting the secretion of dopamine in vivo, and has a certain effect on antidepressant diseases, which however needs further studies.
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Humans , Brain Ischemia , Drug Therapy , Ginkgo biloba , Panax notoginseng , Phytotherapy , Plant Extracts , Therapeutic Uses , Plants, MedicinalABSTRACT
Objective To investigate the effect of capsaicin on cognitive function and the expression of TRPV1 protein in hippocampus of rats with chronic cerebral hypoperfusion (CCH).Methods 60 SD rats were randomly divided into control group (SHAM group),chronic cerebral hypoperfusion group (CCH group),placebo control group(PC group) and capsaicin group(CAP group) with 15 in each group.The chronic cerebral hypoperfusion rat model was established by permanent bilateral common carotid artery occlusion.The rats in CAP group and PC group were given capsaicin and saline respectively by intraperitoneal injection,twice a week.The spatial learning and memory ability and emotion of rats were observed by Morris water maze test and open field test,and the expression of TRPV1 in the hippocampus of rats was detected by Western blot.Results (1) In the open field experiment,compared with the SHAM group (22.60±4.60),the standing times of the CCH group(12.10±2.80) decreased (P＜0.01),but the standing times of CAP group (19.30± 4.16) increased compared with that of h PC group(12.50 ±2.68) (P＜0.01).(2) In Morris water maze test,positioning navigation experiment showed that compared with the SHAM group,the escape latency of the CCH group and the PC group increased (P＜0.05),while the escape latency of CAP group was shorter than that of the PC group (P＜ 0.05).And in the space exploration experiment,compared with the SHAM group (1.87 ± 0.64),the times of crossing the platform in CCH group (0.75 ± 0.89) and the PC group (1.00± 0.93) decreased,while the latency of crossing the platform increased (P＜0.01).And the times of crossing the platform in CAP group((2.38±0.74) increased compared with that of PC group,and the latency of crossing the platform of CAP group decreased compared with that of PC group (P＜0.01).(3) Results of Western blot showed that compared with the SHAM group,the level of TRPV1 in rat hippocampus of CCH group was down regulated (P＜0.05),and the expression of TRPV1 in CAP group was higher than that of PC group (P＜0.05).Conclusion Capsaicin can effectively improve cognitive impairment in rats with chronic cerebral hypoperfusion,which may be related to the up-regulation of TRPV1 protein expression in hippocampal tissues.
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Chronic cerebral hypoperfusion (CCH), which is associated with onset of vascular dementia, causes cognitive impairment and neuropathological alterations in the brain. In the present study, we examined the neuroprotective effect of duloxetine (DXT), a potent and balanced serotonin/norepinephrine reuptake inhibitor, on CCH-induced neuronal damage in the hippocampal CA1 region using a rat model of permanent bilateral common carotid arteries occlusion. We found that treatment with 20 mg/kg DXT could attenuate the neuronal damage, the reduction of phosphorylations of mTOR and p70S6K as well as the elevations of TNF-α and IL-1β levels in the hippocampal CA1 region at 28 days following CCH. These results indicate that DXT displays the neuroprotective effect against CCH-induced hippocampal neuronal death, and that neuroprotective effect of DXT may be closely related with the attenuations of CCH-induced decrease of mTOR/p70S6K signaling pathway as well as CCH-induced neuroinflammatory process.
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Brain , CA1 Region, Hippocampal , Carotid Artery, Common , Cognition Disorders , Dementia, Vascular , Duloxetine Hydrochloride , Models, Animal , Neurons , Neuroprotection , Neuroprotective Agents , Phosphorylation , Ribosomal Protein S6 Kinases, 70-kDaABSTRACT
Vascular dementia (VaD) is a group of heterogeneous diseases with the common feature of cerebral hypoperfusion. To identify key factors contributing to VaD pathophysiology, we performed a detailed comparison of Wistar and Sprague–Dawley (SD) rats subjected to permanent bilateral common carotid artery occlusion (BCCAo). Eight-week old male Wistar and SD rats underwent BCCAo, followed by a reference memory test using a five-radial arm maze with tactile cues. Continuous monitoring of cerebral blood flow (CBF) was performed with a laser Doppler perfusion imaging (LDPI) system. A separate cohort of animals was sacrificed for evaluation of the brain vasculature and white matter damage after BCCAo. We found reference memory impairment in Wistar rats, but not in SD rats. Moreover, our LDPI system revealed that Wistar rats had significant hypoperfusion in the brain region supplied by the posterior cerebral artery (PCA). Furthermore, Wistar rats showed more profound CBF reduction in the forebrain region than did SD rats. Post-mortem analysis of brain vasculature demonstrated greater PCA plasticity at all time points after BCCAo in Wistar rats. Finally, we confirmed white matter rarefaction that was only observed in Wistar rats. Our studies show a comprehensive and dynamic CBF status after BCCAo in Wistar rats in addition to severe PCA dolichoectasia, which correlated well with white matter lesion and memory decline.
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Animals , Humans , Male , Rats , Arm , Brain , Carotid Artery, Common , Cerebrovascular Circulation , Cohort Studies , Cues , Dementia, Vascular , Memory , Passive Cutaneous Anaphylaxis , Perfusion Imaging , Plastics , Posterior Cerebral Artery , Prosencephalon , Rats, Wistar , White MatterABSTRACT
Objective To observe the effect of IcarisideⅡ (ICSⅡ) on spatial learning and memory impairments and axonal regeneration induced by chronic cerebral hypoperfusion (CCH) in rats.Methods 90 male SD rats were randomly divided into normal group,sham operation group,CCH group and ICS Ⅱ low,middle and high-dose treatment groups.The chronic cerebral hypoperfusion model was established by permanent bilateral common carotid artery occlusion.Then these rats in ICS Ⅱ low,middle and high-dose treatment groups were given ICS Ⅱ4,8 and 16 mg/(kg · d) by gavage on the 1st day after modeling.There were 5 rats in every group at each observing time(4,8 and 12 week).Morris water maze experiment was utilized to assess the escape latency and the target quadrant residence time while HE and immunohistochemistry analysis were applied to test the morphology change and expressions of GAP-43,MAP-2 and Nogo-A in hippocampal CA 1.Results Compared with those of sham operation groups at 4,8 and 12 week respectively,the escape latency in CCH group were significantly prolonged(40.02±4.95) s,(42.29±5.75) s,(53.68±6.14) s vs (26.43±2.68) s,(26.84±2.06) s,(31.53±4.12) s,P＜0.05;the target quadrant residence time were significantly reduced(28.53±2.40) s,(28.02±4.28) s,(22.60±4.03) s vs (33.34±2.89) s,(33.31 ±4.14) s,(31.63±2.20)s,P＜0.05);the expressions of GAP-43 and Nogo-A were increased with that of MAP-2 reduced(P＜0.05).Meanwhile,the neuropathological changes with more denatured neurons and less normal neurons were found in hippocampal CA1.However,compared with those of CCH group,the escape latency of ICS Ⅱ middle and high-dose groups (30.58±3.03) s,(29.19±4.23) s,(38.77±5.80) s;(28.90±2.98) s,(26.91 ±6.63) s,(36.51 ±3.98) s) were shortened (P＜0.05);the target quadrant residence time (32.54± 3.41) s,(32.69±3.47) s,(28.27±3.57) s;(32.69±3.54) s,(33.20±4.29) s,(28.07±4.04) s) were increased (P＜ 0.05);the expression of Nogo-A was decreased while those of GAP-43 and MAP-2 were conversely increased (P＜0.05).Moreover,few denatured neurons were observed in hippocampal CA1.But there were no differences for those indexs between CCH group and ICS Ⅱ low-dose treatment groups (P＞0.05).Compared with those in 8 week and 4 week,the escape latency and the target quadrant residence time were prolonged and reduced with the expression of Nogo-A increased in all groups except normal group and sham operation group(P＜0.05),the expressions of GAP-43 and MAP-2 were decreased in CCH group and ICS Ⅱ low-dose treatment group(P＜0.05),but there were no significant differences in ICS Ⅱ middle and high-dose treatment groups at 12 week(P＞0.05).However,there were no statistical significance of all indexes between 8 week and 4 week(P＞0.05).Conclusion ICS Ⅱ can improve the spatial learning and memory in chronic cerebral hypoperfusion rats,which may be achieved by neuroprotective effects and reducing the expression of Nogo-A consequently promotes the regeneration of axons.
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Mammalian target of rapamycin (mTOR) has an important role in various biological processes in cells. In the present study, we investigated temporal changes in mTOR and phosphorylated-mTOR (p-mTOR) expressions in the rat hippocampal CA1 region following chronic cerebral hypoperfusion (CCH) induced by permanent bilateral common carotid arteries occlusion (2VO). The mTOR immunoreactivity in the pyramidal neurons and mTOR protein level in the hippocampal CA1 region were markedly decreased at 21 and 28 days after 2VO surgery. However, p-mTOR protein expression was significantly increased at 7 days following CCH but then decreased with time. The results indicate that mTOR and p-mTOR expressions change in the hippocampal CA1 region after 2VO surgery and that reduced expressions of mTOR and p-mTOR may be closely related to the CCH-induced neuronal damage in the hippocampal CA1 region.
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Animals , Rats , Biological Phenomena , CA1 Region, Hippocampal , Carotid Artery, Common , Dementia, Vascular , Mammals , Neurons , Pyramidal Cells , Sirolimus , TOR Serine-Threonine KinasesABSTRACT
Objective To observe the effects of icarisid Ⅱ (ICS Ⅱ)on cognitive deficits and expression of synaptophysin(SYN)in chronic cerebral hypoperfusion(CCH)rat models.Methods 40 male SD rats were randomly divided into four groups:normal group,sham operation group,model group and ICSⅡgroup.The model was established by permanent bilateral common carotid artery occlusion(BCCAO).ICS Ⅱ group was administered ICS Ⅱ at a dose of 8mg·kg -1 ·d -1 by gavage on 1st day after modeling.Sham group and CCH group were injected double -distilled water.The escape latency(s)and spatial probe times were measured by water maze test.Then,the morphology change and expression of SYN in hippocampal were assayed by HE and immunohistochemistry analysis.Results At the 1st month and 2nd month,the escape latency in the model group[(40.02 ±4.95)s,(42.29 ±5.75)s]were significantly prolonged compared with the sham operation group[(26.43 ±2.68)s,(26.84 ±2.06)s](t =4.89,5.06,all P 0.05 ). Conclusion ICS Ⅱ can improve the cognitive deficits in CCH rat models and this effect may be associated with increased expressions of SYN in hippocampal.