Progressive cognitive impairment following chronic cerebral hypoperfusion induced by permanent occlusion of bilateral carotid arteries in rats

Local transplantation of mesenchymal stem cells improves encephalo-myo-synangiosis-mediated collateral neovascularization in chronic brain ischemia

BACKGROUND

To explore whether local transplantation of mesenchymal stem cells (MSCs) in temporal muscle can promote collateral angiogenesis and to analyze its main mechanisms of promoting angiogenesis.

METHODS

Bilateral carotid artery stenosis (BCAS) treated mice were administrated with encephalo-myo-synangiosis (EMS), and bone marrow mesenchymal stem cells (BMSCs) were transplanted into the temporal muscle near the cerebral cortex. On the 30th day after EMS, the Morris water maze, immunofluorescence, laser speckle imaging, and light sheet microscopy were performed to evaluate angiogenesis; In addition, rats with bilateral common carotid artery occlusion were also followed by EMS surgery, and BMSCs from GFP reporter rats were transplanted into the temporal muscle to observe the survival time of BMSCs. Then, the concentrated BMSC-derived conditioned medium (BMSC-CM) was used to stimulate HUVECs and BMECs for ki-67 immunocytochemistry, CCK-8, transwell and chick chorioallantoic membrane assays. Finally, the cortical tissue near the temporal muscle was extracted after EMS, and proteome profiler (angiogenesis array) as well as RT-qPCR of mRNA or miRNA was performed.

RESULTS

The results of the Morris water maze 30 days after BMSC transplantation in BCAS mice during the EMS operation, showed that the cognitive impairment in the BCAS + EMS + BMSC group was alleviated (P < 0.05). The results of immunofluorescence, laser speckle imaging, and light sheet microscopy showed that the number of blood vessels, blood flow and astrocytes increased in the BCAS + EMS + BMSC group (P < 0.05). The BMSCs of GFP reporter rats were applied to EMS and showed that the transplanted BMSCs could survive for up to 14 days. Then, the results of ki-67 immunocytochemistry, CCK-8 and transwell assays showed that the concentrated BMSC-CM could promote the proliferation and migration of HUVECs and BMECs (P < 0.05). Finally, the results of proteome profiler (angiogenesis array) in the cerebral cortex showed that the several pro-angiogenesis factors (such as MMP-3, MMP-9, IGFBP-2 or IGFBP-3) were notably highly expressed in MSC transplantation group compared to others.

CONCLUSIONS

Local MSCs transplantation together with EMS surgery can promote angiogenesis and cognitive behavior in chronic brain ischemia mice. Our study illustrated that MSC local transplantation can be the potential therapeutical option for improving EMS treatment efficiency which might be translated into clinical application.

Microvascular Contributions to Alzheimer Disease Pathogenesis: Is Alzheimer Disease Primarily an Endotheliopathy?

Alzheimer disease (AD) models are based on the notion that abnormal protein aggregation is the primary event in AD, which begins a decade or longer prior to symptom onset, and culminates in neurodegeneration; however, emerging evidence from animal and clinical studies suggests that reduced blood flow due to capillary loss and endothelial dysfunction are early and primary events in AD pathogenesis, which may precede amyloid and tau aggregation, and contribute to neuronal and synaptic injury via direct and indirect mechanisms. Recent data from clinical studies suggests that endothelial dysfunction is closely associated with cognitive outcomes in AD and that therapeutic strategies which promote endothelial repair in early AD may offer a potential opportunity to prevent or slow disease progression. This review examines evidence from clinical, imaging, neuropathological, and animal studies supporting vascular contributions to the onset and progression of AD pathology. Together, these observations support the notion that the onset of AD may be primarily influenced by vascular, rather than neurodegenerative, mechanisms and emphasize the importance of further investigations into the vascular hypothesis of AD.

Effects of Ceftriaxone on Oxidative Stress and Inflammation in a Rat Model of Chronic Cerebral Hypoperfusion

Ceftriaxone (CTX) exerts a neuroprotective effect by decreasing glutamate excitotoxicity. We further studied the underlying mechanisms and effects of CTX early post-treatment on behavior in a cerebral hypoperfusion rats. The rats’ common carotid arteries (2VO) were permanently ligated. CTX was treated after ischemia. Biochemical studies were performed to assess antioxidative stress and inflammation. Behavioral and histological studies were then tested on the ninth week after vessel ligation. The 2VO rats showed learning and memory deficits as well as working memory impairments without any motor weakness. The treatment with CTX was found to attenuate white matter damage, MDA production, and interleukin 1 beta and tumor necrosis factor alpha production, mainly in the hippocampal area. Moreover, CTX treatment could increase the expression of glia and the glial glutamate transporters, and the neuronal glutamate transporter. Taken together, our data indicate the neuroprotective mechanisms of CTX involving the upregulation of glutamate transporters’ expression. This increased expression contributes to a reduction in glutamate excitotoxicity and oxidative stress as well as pro-inflammatory cytokine production, thus resulting in the protection of neurons and tissue from further damage. The present study highlights the mechanism of the effect of CTX treatment and of the underlying ischemia-induced neuronal damage.

Tianma Formula Alleviates Dementia via ACER2-Mediated Sphingolipid Signaling Pathway Involving Aβ

Objective

To reveal the molecular mechanism of the antagonistic effect of traditional Chinese medicine Tianma formula (TF) on dementia including vascular dementia (VaD) and Alzheimer's disease (AD) and to provide a scientific basis for the study of traditional Chinese medicine for prevention and treatment of dementia.

Method

The TF was derived from the concerted application of traditional Chinese medicine. We detected the pharmacological effect of TF in VaD rats. The molecular mechanism of TF was examined by APP/PS1 mice in vivo, Caenorhabditis elegans (C. elegans) in vitro, ELISA, pathological assay via HE staining, and transcriptome. Based on RNA-seq analysis in VaD rats, the differentially expressed genes (DEGs) were identified and then verified by quantitative PCR (qPCR) and ELISA. The molecular mechanisms of TF on dementia were further confirmed by network pharmacology and molecular docking finally.

Results

The Morris water maze showed that TF could improve the cognitive memory function of the VaD rats. The ELISA and histological analysis suggested that TF could protect the hippocampus via reducing tau and IL-6 levels and increasing SYN expression. Meanwhile, it could protect the neurological function by alleviating Aβ deposition in APP/PS1 mice and C. elegans. In the RNA-seq analysis, 3 sphingolipid metabolism pathway-related genes, ADORA3, FCER1G, and ACER2, and another 5 nerve-related genes in 45 key DEGs were identified, so it indicated that the protection mechanism of TF was mainly associated with the sphingolipid metabolism pathway. In the qPCR assay, compared with the model group, the mRNA expressions of the 8 genes mentioned above were upregulated, and these results were consistent with RNA-seq. The protein and mRNA levels of ACER2 were also upregulated. Also, the results of network pharmacology analysis and molecular docking were consistent with those of RNA-seq analysis.

Conclusion

TF alleviates dementia by reducing Aβ deposition via the ACER2-mediated sphingolipid signaling pathway.

Potential therapeutic agents for ischemic white matter damage

Ischemic white matter damage (WMD) is increasingly being considered as one of the major causes of neurological disorders in older adults and preterm infants. The functional consequences of WMD triggers a progressive cognitive decline and dementia particularly in patients with ischemic cerebrovascular diseases. Despite the major stride made in the pathogenesis mechanisms of ischemic WMD in the last century, effective medications are still not available. So, there is an urgent need to explore a promising approach to slow the progression or modify its pathological course. In this review, we discussed the animal models, the pathological mechanisms and the potential therapeutic agents for ischemic WMD. The development in the studies of anti-oxidants, free radical scavengers, anti-inflammatory or anti-apoptotic agents and neurotrophic factors in ischemic WMD were summarized. The agents which either alleviate oligodendrocyte damage or promote its proliferation or differentiation may have potential value for the treatment of ischemic WMD. Moreover, drugs with multifaceted protective activities or a wide therapeutic window may be optimal for clinical translation.

Neural dysfunctions following experimental permanent occlusions of bilateral common carotid arteries cause an increase of rat voluntary alcohol drinking behavior

We have previously reported that ischemic animal models treated with a respiratory inhibitor, rotenon, show an increased voluntary alcohol intake. Although it is clear that ischemic brain, as a result of reduced-blood flow, shows pathological events and/or neuro-degenerations apparently, little is known of causal relationship between the mechanism of neural dysfunction and voluntary alcohol consumption. Authors have investigated effects of permanent two-vessel occlusion (p2VO) on rat voluntary alcohol drinking behavior. In first experiment the p2VO-treated rats showed an increase of voluntary alcohol drinking behavior, as compared with sham controls. Using brain microdialysis technique, increases of only nucleus accumbens (ACC) dopamine (DA) releases were suppressed in the p2VO-treated rats significantly, following the high K⁺ (40 mM) perfusion through the microdialysis probe membrane. Alcohol (200 mM) perfusion-induced DA and serotonin (5-HT) releases in the ACC of the p2VO-treated rats were suppressed significantly in the second experiment, as compared with the sham-treated rats. In third experiment p2VO-treated rats showed significant decreases of the contents of DA, not 5-HT, in the ACC, caudate-putamen (C/P), ventral tegmental area-substantia nigra (VT/SN) and lateral hypothalamus (LH). Dopaminergic neurons in the ACC showed more functional vulnerability against the p2VO treatments, as compared with the serotonergic neurons. An increase of alcohol intake in the p2VO-treated rats means the compensation for the neural degeneration of the dopaminergic system in the ACC consisted brain rewarding system. It was likely suggested that neural disturbance of higher functions involved with incomplete global brain ischemia leads the risk of an abnormal alcohol drinking in human.

Chronic stepwise cerebral hypoperfusion differentially induces synaptic proteome changes in the frontal cortex, occipital cortex, and hippocampus in rats

During chronic cerebral hypoperfusion (CCH), the cerebral blood flow gradually decreases, leading to cognitive impairments and neurodegenerative disorders, such as vascular dementia. The reduced oxygenation, energy supply induced metabolic changes, and insufficient neuroplasticity could be reflected in the synaptic proteome. We performed stepwise bilateral common carotid occlusions on rats and studied the synaptic proteome changes of the hippocampus, occipital and frontal cortices. Samples were prepared and separated by 2-D DIGE and significantly altered protein spots were identified by HPLC–MS/MS. We revealed an outstanding amount of protein changes in the occipital cortex compared to the frontal cortex and the hippocampus with 94, 33, and 17 proteins, respectively. The high alterations in the occipital cortex are probably due to the hypoxia-induced retrograde degeneration of the primary visual cortex, which was demonstrated by electrophysiological experiments. Altered proteins have functions related to cytoskeletal organization and energy metabolism. As CCH could also be an important risk factor for Alzheimer’s disease (AD), we investigated whether our altered proteins overlap with AD protein databases. We revealed a significant amount of altered proteins associated with AD in the two neocortical areas, suggesting a prominent overlap with the AD pathomechanism.

Characterization of Gut Microbiota in Prenatal Cold Stress Offspring Rats by 16S rRNA Sequencing

Simple Summary

Prenatal stress, including prenatal cold stress has long-term effects on offspring’s physical and mental health. Our previous study showed a reduction of anxiety-like behavior in offspring rats suffered from prenatal cold stress. It is well-known that gut microbiota was involved in a variety of physiological activities, such as emotion, cognition, and behavior. However, information on the comparison between prenatal cold stress and gut microbiota in offspring is limited. The current study compared the gut microbiota composition of the prenatal cold stress and non-stress offspring rats. Cold stressed during gestation period showed to change the offspring gut microbiota composition, and Bacteroides and Lactobacillus were significantly increased in prenatal cold stress offspring rat guts. With the hope, cold stress-induced negative effects of animals can be prevented by microbiological interventions.

Abstract

Our previous study showed a reduction of anxiety-like behavior in offspring rats suffered from prenatal cold stress; whether this was related to changes in the offspring gut microbiota is unclear. To obtain the evidence for the role of the gut microbiota in prenatal cold stress offspring, 16S rRNA sequencing technology was used. Male and female offspring rat feces were collected from a room temperature group and a prenatal cold stress group (n ≥ 8) for microbial DNA extraction, followed by 16S rRNA sequencing. The results indicated that prenatal cold stress could change the offspring’s gut microbiota composition. Prenatal cold stress significantly upregulates Lactobacillus, Lactobacillus_gasseri, Bacteroides, and Bacteroides-acidifaciens in female offspring, whereas prenatal cold stress significantly reduced Lachnospiraceae and Prevotellaceae in male offspring. These data showed the characterization of gut microbiota in prenatal cold stress offspring rats, and these data suggest that microbiological intervention in the future can potentially prevent the negative effects caused by cold stress to animals.

TGF-β Signaling: A Therapeutic Target to Reinstate Regenerative Plasticity in Vascular Dementia?

Vascular dementia (VaD) is the second leading form of memory loss after Alzheimer's disease (AD). Currently, there is no cure available. The etiology, pathophysiology and clinical manifestations of VaD are extremely heterogeneous, but the impaired cerebral blood flow (CBF) represents a common denominator of VaD. The latter might be the result of atherosclerosis, amyloid angiopathy, microbleeding and micro-strokes, together causing blood-brain barrier (BBB) dysfunction and vessel leakage, collectively originating from the consequence of hypertension, one of the main risk factors for VaD. At the histopathological level, VaD displays abnormal vascular remodeling, endothelial cell death, string vessel formation, pericyte responses, fibrosis, astrogliosis, sclerosis, microglia activation, neuroinflammation, demyelination, white matter lesions, deprivation of synapses and neuronal loss. The transforming growth factor (TGF) β has been identified as one of the key molecular factors involved in the aforementioned various pathological aspects. Thus, targeting TGF-β signaling in the brain might be a promising therapeutic strategy to mitigate vascular pathology and improve cognitive functions in patients with VaD. This review revisits the recent understanding of the role of TGF-β in VaD and associated pathological hallmarks. It further explores the potential to modulate certain aspects of VaD pathology by targeting TGF-β signaling.

Germinated Brown Rice Attenuates Cell Death in Vascular Cognitive Impaired Mice and Glutamate-Induced Toxicity In HT22 Cells

Germinated brown rice (GBR) with unpolishing, soaking, and germinating processes can improve the texture, flavor, and nutritional value, including GABA and phenolic contents. The effect of GBR was first investigated in vascular cognitive impaired mice and glutamate-induced toxicity in HT22 cells with respect to standard pure GABA. Feeding mice with GBR for 5 weeks showed neuroprotection. In this study, the modified bilateral common carotid artery occlusion mice model was mild but a significant difference in cognitive impairment was still shown. Like pure GABA, GBR decreased cognitive deficits in memory behavioral tests and significantly attenuated hippocampal neuronal cell death at P < 0.001. Similarly to 0.125 μM of GABA, 100 μg/mL of GBR increased HT22 cell viability after glutamate toxicity. GBR affected less apoptotic cell death and less blocking by the GABA_A antangonist bicuculline in comparison to GABA. When the results are taken together, the underlying mechanism of GBR protection may mediate though the GABA_A receptor and its phenolic contents.

Effects of resveratrol on learning and memory in rats with vascular dementia

The purpose of the present study was to study the effects of resveratrol on cognitive function in rats with vascular dementia and to investigate the molecular mechanisms of its neuroprotective effects. Forty-five SD rats were randomly divided into 3 groups: The control group (Con group, n=15), the model group (VD group, n=15) and the resveratrol-treated VD group (Res group, n=15). The VD rats (the VD group and the Res group) were generated by bilateral common carotid artery occlusion. The rats in the Res group received daily resveratrol treatment intraperitoneally for 4 weeks. Cognitive function was tested using the Morris water maze test. The levels of SOD and MDA (oxidative stress indicators) were detected by ELISA kits. The protein expression of Bax, Bcl-2 and caspase-3 was detected by western blotting. Compared with the rats in the Con group, the rats in the VD group exhibited decreased cognitive function, significantly increased hippocampal content of MDA, Bax and caspase-3 (P<0.05), and significantly reduced hippocampal expression of SOD and Bcl-2 (P<0.05). Compared with the rats in the VD group, the rats in the Res group exhibited increased cognitive ability, reduced hippocampal content of MDA, Bax and caspase-3 (P<0.05), and increased hippocampal expression of SOD and Bcl-2 (P<0.05). Resveratrol treatment significantly improved the spatial learning and memory of the VD rats. The mechanism associated with the neuroprotective effects of resveratrol may be closely related to the inhibition of the apoptosis pathway and oxidative stress injury.

Quantitative measurement of regional cerebral blood flow and oxygen metabolism in a rat model of cerebral hypoperfusion

This study was aimed at evaluating the regional changes in the cerebral metabolic rate of oxygen (CMRO₂) in relation to the cerebral blood flow (CBF) in the bilateral common carotid artery occlusion (BCAO) rat model. Ligation of the bilateral common carotid arteries (or a sham operation in control animals) was performed in 10-week-old male Wistar rats. O-15 PET images were acquired in the subacute phase (1 week after the surgery) and chronic phase (6 weeks after the surgery) with the animals under anesthesia, using a small-animal PET system and the O-15 gas steady-state inhalation method with arterial blood sampling developed in our previous study. Histopathological staining by Klüver-Barrera method and immunocytochemistry staining by glial fibrillary acidic protein were performed. Cognitive function was tested by using the apparatus of Y-maze. Significantly lower CBF and higher oxygen extraction fraction were observed in broad areas of the cerebrum in the subacute phase in the BCAO rats, with recovery in the chronic phase. A stable decrease of the CMRO₂ in the subacute phase of arterial occlusion and later was observed in the BCAO rat model, mainly in the anterior cerebral artery territory. Atrophy and rarefaction of corpus callosum were found in the BCAO in the chronic phase. Activity of astrocytes in the BCAO was prominent in the both phases. Working memory was impaired in the BCAO in the chronic phase. Regional changes in cerebral perfusion and oxygen metabolism in the subacute and chronic phases of arterial occlusion were clarified in a rat model of BCAO by quantitative O-15 PET based on the steady-state method.

3'-Daidzein Sulfonate Sodium Protects Against Chronic Cerebral Hypoperfusion-Mediated Cognitive Impairment and Hippocampal Damage via Activity-Regulated Cytoskeleton-Associated Protein Upregulation

The learning and memory impairment caused by chronic cerebral hypoperfusion (CCH) is permanent and seriously affects the daily life of patients and their families. The compound 3'-daidzein sulfonate sodium (DSS) protects against CCH-mediated memory impairment and hippocampal damage in a rat model. In the present study, we further investigated the underlying mechanisms of this effect in the rat two-vessel occlusion (2VO) and the oxygen and glucose deprivation (OGD) primary hippocampal neuron models. The hippocampal expression of the activity-regulated cytoskeleton associated protein (Arc) following DSS administration was detected in vivo and in vitro and behavioral testing was used to investigate the role of Arc in the DSS-mediated rescue of CCH-induced neurotoxicity. DSS increased hippocampal Arc expression both in vivo and in vitro. Arc overexpression increased and Arc knockdown decreased hippocampal neuronal densities in rat 2VO model, when compared to DSS treatment alone. Arc overexpression decreased and Arc knockdown increased apoptotic hippocampal neurons in rat 2VO and OGD primary hippocampal neuron models, when compared to DSS treatment alone. Arc overexpression enhanced and Arc knockdown inhibited the beneficial effect of DSS on 2VO-induced cognitive impairment. DSS restored the neuronal OGD-mediated phosphorylation decrease in protein kinase alpha (PKA), extracellular signal-regulated protein kinases 1/2 (ERK1/2) and cAMP response element binding protein (CREB), in vitro. PKA and ERK1/2 inhibition blocked the DSS-mediated effects on neuronal apoptosis and OGD-induced Arc downregulation. In conclusion, DSS protects against CCH-mediated cognitive impairment and hippocampal damage via Arc upregulation, which is activated by the PKA/CREB and ERK/CREB signaling pathways. Our study further confirms the potential use of DSS as an effective treatment for CCH-associated diseases.

Protective effects of sulforaphane in experimental vascular cognitive impairment: Contribution of the Nrf2 pathway

The major pathophysiological process of vascular cognitive impairment (VCI) is chronic cerebral ischemia, which causes disintegration of the blood-brain barrier (BBB), neuronal death, and white matter injury. This study aims to test whether sulforaphane (Sfn), a natural activator of nuclear factor erythroid 2-related factor 2 (Nrf2), reduces the chronic ischemic injury and cognitive dysfunction after VCI. Experimental VCI was induced in rats by permanent occlusion of both common carotid arteries for six weeks. This procedure caused notable neuronal death in the cortex and hippocampal CA1, myelin loss in the corpus callosum and hippocampal fimbria, accumulation of myelin debris in the corpus callosum, and remarkable cognitive impairment. Sfn treatment alleviated these ischemic injuries and the cognitive dysfunction. Sfn-mediated neuroprotection was associated with enhanced activation of Nrf2 and upregulation of heme oxygenase 1. Sfn also reduced neuronal and endothelial death and maintained the integrity of BBB after oxygen-glucose deprivation in vitro in an Nrf2 dependent manner. Furthermore, Nrf2 knockdown in endothelial cells decreased claudin-5 protein expression with downregulated claudin-5 promoter activity, suggesting that claudin-5 might be a target gene of Nrf2. Our results demonstrate that Sfn provides robust neuroprotection against chronic brain ischemic injury and may be a promising agent for VCI treatment.

Ambiguous Effects of Autophagy Activation Following Hypoperfusion/Ischemia

Autophagy primarily works to counteract nutrient deprivation that is strongly engaged during starvation and hypoxia, which happens in hypoperfusion. Nonetheless, autophagy is slightly active even in baseline conditions, when it is useful to remove aged proteins and organelles. This is critical when the mitochondria and/or proteins are damaged by toxic stimuli. In the present review, we discuss to that extent the recruitment of autophagy is beneficial in counteracting brain hypoperfusion or, vice-versa, its overactivity may per se be detrimental for cell survival. While analyzing these opposite effects, it turns out that the autophagy activity is likely not to be simply good or bad for cell survival, but its role varies depending on the timing and amount of autophagy activation. This calls for the need for an appropriate autophagy tuning to guarantee a beneficial effect on cell survival. Therefore, the present article draws a theoretical pattern of autophagy activation, which is hypothesized to define the appropriate timing and intensity, which should mirrors the duration and severity of brain hypoperfusion. The need for a fine tuning of the autophagy activation may explain why confounding outcomes occur when autophagy is studied using a rather simplistic approach.

Histidine Alleviates Impairments Induced by Chronic Cerebral Hypoperfusion in Mice

Chronic cerebral hypoperfusion is one of the fundamental pathological causes of brain disease such as vascular dementia. Exploration of effective treatments for this is of great interest. Histidine has been reported to be effective in anti-apoptosis, antioxidant, and against excitotoxicity. In the present study, we aim to investigate whether histidine could have a therapeutic effect on the impairments induced by chronic cerebral hypoperfusion. Cerebral hypoperfusion model was established through bilateral common carotid arteries stenosis (BCAS) operation in Tie2-GFP mice. Radial arm maze and Morris water maze revealed that histidine showed potential improvement of the tendency of cognitive impairments induced by hypoperfusion. The possible mechanisms were further investigated. After administration of histidine in hypoperfusion mice, immunofluorescent BrdU staining revealed more new-born nerve cells. In vivo observation through a cranial window under two-photon laser-scanning microscopy demonstrated that the blood flow velocity in capillary was improved, the distance between the astrocytes and the penetrating artery was shortened. Histidine administration also significantly increased the protein expression level of zonula occludens protein 1, an indicator of the integrity of blood–brain barrier (BBB). These results suggest that histidine could alleviate the impairments induced by chronic cerebral hypoperfusion in mice, and this effect may be related to the neurogenesis, astrocytes, and the integrity of the BBB.

Xiaoshuan enteric-coated capsule alleviates cognitive impairment by enhancing hippocampal glucose metabolism, hemodynamics and neuroplasticity of rat with chronic cerebral hypoperfusion

Chronic cerebral hypoperfusion (CCH) is identified as a critical risk factor of dementia in patients with cerebrovascular disease. Xiaoshuan enteric-coated capsule (XSECC) is a compound Chinese medicine approved by Chinese State Food and Drug Administration for promoting brain remodeling and plasticity after stroke. The present study aimed to explore the potential of XSECC to improve cognitive function after CCH and further investigate the underlying mechanisms. CCH was induced by bilateral common carotid artery occlusion (BCCAO) in rats. XSECC (420 or 140 mg/kg) treatment remarkably reversed BCCAO-induced cognitive deficits. Notably, after XSECC treatment, magnetic resonance angiography combined with arterial spin labeling noninvasively demonstrated significantly improved hippocampal hemodynamics, and ¹⁸F-FDG PET/CT showed enhanced hippocampal glucose metabolism. In addition, XSECC treatment markedly alleviated neuropathologies and improved neuroplasticity in the hippocampus. More importantly, XSECC treatment facilitated axonal remodeling by regulating the phosphorylation of axonal growth related proteins including protein kinase B (AKT), glycogen synthase kinase-3β (GSK-3β) and collapsin response mediator protein-2 (CRMP2) in the hippocampus. Taken together, the present study demonstrated the beneficial role of XSECC in alleviating BCCAO-induced cognitive deficits by enhancing hippocampal glucose metabolism, hemodynamics and neuroplasticity, suggesting that XSECC could be a useful strategy in cerebral hypoperfusion state and dementia.

Effects of repetitive transcranial magnetic stimulation on cognitive function and cholinergic activity in the rat hippocampus after vascular dementia

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive treatment that can enhance the recovery of neurological function after stroke. Whether it can similarly promote the recovery of cognitive function after vascular dementia remains unknown. In this study, a rat model for vascular dementia was established by the two-vessel occlusion method. Two days after injury, 30 pulses of rTMS were administered to each cerebral hemisphere at a frequency of 0.5 Hz and a magnetic field intensity of 1.33 T. The Morris water maze test was used to evaluate learning and memory function. The Karnovsky-Roots method was performed to determine the density of cholinergic neurons in the hippocampal CA1 region. Immunohistochemical staining was used to determine the number of brain-derived neurotrophic factor (BDNF)-immunoreactive cells in the hippocampal CA1 region. rTMS treatment for 30 days significantly improved learning and memory function, increased acetylcholinesterase and choline acetyltransferase activity, increased the density of cholinergic neurons, and increased the number of BDNF-immunoreactive cells. These results indicate that rTMS can ameliorate learning and memory deficiencies in rats with vascular dementia. The mechanism through which this occurs might be related to the promotion of BDNF expression and subsequent restoration of cholinergic system activity in hippocampal CA1 region.

MicroRNA-181c Ameliorates Cognitive Impairment Induced by Chronic Cerebral Hypoperfusion in Rats

Chronic cerebral hypoperfusion (CCH) characterized by global cerebral ischemia is an important risk factor contributing to the development of dementia. MicroRNAs (miRNAs) play important roles in the cellular adaptation to long-term ischemia/hypoxia by turning off or on the expression of target genes. MiR-181c is widely expressed in the nervous system, and tripartite motif 2 (TRIM2) is one of its target genes. In this work, we had identified that progressive spatial memory deficiency was induced in the bilateral common carotid artery occlusion (2-VO) rat models. Meanwhile, inhibition of miR-181c expression and upregulation of TRIM2 in the hippocampus of 2-VO rats were found accompanying with reduction in the dendritic branching and dendrite spine density of the hippocampal neurons. Viral vector-mediated miR-181c delivery might improve the cognitive deficiency via TRIM2 on neurofilament light (NF-L) ubiquitination resulting in remodeling of the hippocampal neurons as well as increase in N-methyl-D-aspartate receptor 1 (NR1) subunit cell surface expression. Meanwhile, miR-181c might rescue the cellular activity from ischemia/hypoxia. These results indicated a novel miRNA-mediated mechanism involving miR-181c and TRIM2 in the cognitive impairment induced by CCH and provided a rationale for the development of miRNA-based strategies for prevention of dementia.

Chronic cerebral hypoperfusion and plasticity of the posterior cerebral artery following permanent bilateral common carotid artery occlusion

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.

Cannabinoid receptor agonist WIN55,212-2 and fatty acid amide hydrolase inhibitor URB597 ameliorate neuroinflammatory responses in chronic cerebral hypoperfusion model by blocking NF-κB pathways

The present study explored the protective effects of cannabinoid receptor agonist WIN55,212-2 (WIN) and fatty acid amide hydrolase inhibitor URB597 (URB) against neuroinflammation in rats with chronic cerebral hypoperfusion (CCH). Activated microglia, astrocytes, and nuclear factor kappa B (NF-κB) p65-positive cells were measured by immunofluorescence. Reactive oxygen species (ROS) was assessed by dihydroethidium staining. The protein levels of cluster of differentiation molecule 11b (OX-42), glial fibrillary acidic protein (GFAP), NF-κB p65, inhibitor of kappa B alpha (IκB-a), IκB kinase a/β (IKK a/β), phosphorylated IKK a/β (p-IKK a/β), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), tumor necrosis factor (TNF)-α, and interleukin-1β (IL-1β) were examined by western blotting or enzyme-linked immunosorbent assay. All the protein levels of OX-42, GFAP, TNF-a, IL-1β, COX-2, and iNOS are increased in CCH rats. WIN and URB downregulated the levels of OX-42, GFAP, TNF-α, IL-1β, COX-2 and iNOS and inhibited CCH-induced ROS accumulation in CCH rats, indicating that WIN and URB might exert their neuroprotective effects by inhibiting the neuroinflammatory response. In addition, the NF-κB signaling pathway was activated by CCH in frontal cortex and hippocampus, while the aforementioned changes were reversed by WIN and URB treatment. These findings suggest that WIN and URB treatment ameliorated CCH-induced neuroinflammation through inhibition of the classical pathway of NF-κB activation, resulting in mitigation of chronic ischemic injury.

Electroacupuncture Improves Cognitive Deficits through Increasing Regional Cerebral Blood Flow and Alleviating Inflammation in CCI Rats

Objective. To investigate the effect of EA on regional cerebral blood flow, cognitive deficits, inflammation, and its probable mechanisms in chronic cerebral ischemia (CCI) rats. Methods. Rats were assigned randomly into sham operation group (sham group) and operation group. For operation group, CCI model was performed using the permanent bilateral common carotid artery occlusion (BCCAO) method, and then rats were further randomly divided into model group and electroacupuncture (EA) group. 2/15 Hz low-frequency pulse electric intervention was applied at “Baihui” and “Dazhui” acupoints in EA group. Four weeks later, Morris water maze test was adopted to assess the cognitive function, using laser Doppler flowmetry to test changes of regional cerebral blood flow (rCBF); double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) to measure proinflammatory cytokines (IL-6, TNF-α, and IL-1β); western blot to test the protein expression quantities of proinflammatory cytokines, JAK2, and STAT3; and RT-PCR to test JAK2 mRNA and STAT3 mRNA in the hippocampus in each group. Results. Compared with the model group, learning and memory abilities and rCBF and IL-6 expression of the EA group enhanced markedly; IL-1β and JAK2 significantly decreased; TNF-α and STAT3 also declined, but the difference was not apparent. Conclusion. Our research suggests that EA can improve cognitive deficits which may be induced by increasing rCBF and anti-inflammatory effect.

Edaravone injection reverses learning and memory deficits in a rat model of vascular dementia

Edaravone is a novel free radical scavenger that exerts neuroprotective effects by inhibiting endothelial injury and by ameliorating neuronal damage in brain ischemia. Recently, it was reported that edaravone could alleviate the pathology and cognitive deficits of Alzheimer's disease patients. However, its relevance to vascular dementia (VaD) is not clear. In this study, we partially occluded the bilateral carotid arteries of rats surgically to induce chronic cerebral hypoperfusion (CCH), a well-known rat model of VaD. Water maze and step-down inhibitory test were used to evaluate the memory deficit. The activities of superoxide dismutase (SOD) and lactate dehydrogenase (LDH), the content of malondialdehyde (MDA) and total reactive oxygen species were measured to evaluate the oxidative stress level. Western blot analysis was used to evaluate the synaptic protein expression. It was found that treatment with edaravone for a 5-week period was able to reverse both spatial and fear-memory deficits in rats with CCH. Edaravone significantly reduced the level of oxidative stress in the brains of rats with CCH by increasing SOD activity and decreasing the content of MDA, LDH, and total reactive oxygen species. Furthermore, edaravone treatment also restored the levels of multiple synaptic proteins in the hippocampi of rats with CCH. Our data provide direct evidence supporting the neuroprotective effects of edaravone in VaD. We propose that the alleviation of oxidative stress and restoration of synaptic proteins play important roles in neuroprotection.

Cinepazide Maleate Improves Cognitive Function and Protects Hippocampal Neurons in Diabetic Rats with Chronic Cerebral Hypoperfusion

To determine the combined effect of type 2 diabetes (T2D) and chronic cerebral hypoperfusion (CCH) on learning and spatial memory, we developed a rat model of CCH by permanent occlusion of bilateral common carotid arteries (2-vessel occlusion (2VO)) in high-fat diet (HFD)-fed rats injected with low-dose streptozotocin (STZ). Furthermore, we examined the effect of cinepazide maleate (CM) on cognitive deficits and brain damage in this rat model. Rats were maintained on HFD for 6 weeks and then injected with 35 mg/kg STZ to induce T2D. Sham or 2VO surgery was performed in non-diabetic or diabetic (DM) rats to obtain four groups: blank, DM, CCH, and DM-CCH groups. Cognitive function was tested by the Morris water maze (MWM) test. To determine the effects of the vasodilator cinepazide maleate (CM) on cognitive deficits and brain damage, DM-CCH rats were administered with 10 mg/kg CM or saline daily for 14 d. Neuronal damage in DM-CCH rats was associated with increased expression of glial fibrillary acidic protein (GFAP) and β-secretase 1 (BACE1), but decreased expression of choline acetyltransferase (ChAT). Moreover, the levels of all these proteins were significantly alleviated by CM treatment. These results suggest that T2D exacerbated CCH-induced brain damage and cognitive impairment, and CM ameliorated these effects.

Activation of GABAB2 subunits alleviates chronic cerebral hypoperfusion-induced anxiety-like behaviours: A role for BDNF signalling and Kir3 channels

Anxiety is an affective disorder that is commonly observed after irreversible brain damage induced by cerebral ischemia and can delay the physical and cognitive recovery, which affects the quality of life of both the patient and family members. However, anxiety after ischemia has received less attention, and mechanisms underlying anxiety-like behaviours induced by chronic cerebral ischemia are under-investigated. In the present study, the chronic cerebral hypoperfusion model was established by the permanent occlusion of the bilateral common carotid arteries (two-vessel occlusion, 2VO) in rats, and anxiety-related behaviours were evaluated. Results indicated that 2VO induced obvious anxiety-like behaviours; the surface expressions of GABAB2 subunits were down-regulated; Brain derived neurotrophic factor (BDNF), tyrosine kinase B (TrkB) and neural cell adhesion molecule (NCAM) were reduced; Meanwhile, the surface expressions of G protein-activated inwardly rectifying potassium (GIRK, Kir3) channels were up-regulated in hippocampal CA1 in 2VO rats. Baclofen, a GABAB receptor agonist, significantly ameliorated the anxiety-like behaviours. It also improved the down-regulation of GABAB2 surface expressions, restored the levels of BDNF, TrkB and NCAM, and reversed the increased surface expressions of Kir3 in hippocampal CA1 in 2VO rats. However, the effects of baclofen were absent in shRNA-GABAB2 infected 2VO rats. These results suggested that activation of GABAB2 subunits could improve BDNF signalling and reverse Kir3 channel surface expressions in hippocampal CA1, which may alleviate the anxiety-like behaviours in rats with chronic cerebral hypoperfusion.

Cerebral hypoperfusion and glucose hypometabolism: Key pathophysiological modulators promote neurodegeneration, cognitive impairment, and Alzheimer's disease

Aging, hypertension, diabetes, hypoxia/obstructive sleep apnea (OSA), obesity, vitamin B12/folate deficiency, depression, and traumatic brain injury synergistically promote diverse pathological mechanisms including cerebral hypoperfusion and glucose hypometabolism. These risk factors trigger neuroinflammation and oxidative-nitrosative stress that in turn decrease nitric oxide and enhance endothelin, Amyloid-β deposition, cerebral amyloid angiopathy, and blood-brain barrier disruption. Proinflammatory cytokines, endothelin-1, and oxidative-nitrosative stress trigger several pathological feedforward and feedback loops. These upstream factors persist in the brain for decades, upregulating amyloid and tau, before the cognitive decline. These cascades lead to neuronal Ca²⁺ increase, neurodegeneration, cognitive/memory decline, and Alzheimer's disease (AD). However, strategies are available to attenuate cerebral hypoperfusion and glucose hypometabolism and ameliorate cognitive decline. AD is the leading cause of dementia among the elderly. There is significant evidence that pathways involving inflammation and oxidative-nitrosative stress (ONS) play a key pathophysiological role in promoting cognitive dysfunction. Aging and several comorbid conditions mentioned above promote diverse pathologies. These include inflammation, ONS, hypoperfusion, and hypometabolism in the brain. In AD, chronic cerebral hypoperfusion and glucose hypometabolism precede decades before the cognitive decline. These comorbid disease conditions may share and synergistically activate these pathophysiological pathways. Inflammation upregulates cerebrovascular pathology through proinflammatory cytokines, endothelin-1, and nitric oxide (NO). Inflammation-triggered ONS promotes long-term damage involving fatty acids, proteins, DNA, and mitochondria; these amplify and perpetuate several feedforward and feedback pathological loops. The latter includes dysfunctional energy metabolism (compromised mitochondrial ATP production), amyloid-β generation, endothelial dysfunction, and blood-brain-barrier disruption. These lead to decreased cerebral blood flow and chronic cerebral hypoperfusion- that would modulate metabolic dysfunction and neurodegeneration. In essence, hypoperfusion deprives the brain from its two paramount trophic substances, viz., oxygen and nutrients. Consequently, the brain suffers from synaptic dysfunction and neuronal degeneration/loss, leading to both gray and white matter atrophy, cognitive dysfunction, and AD. This Review underscores the importance of treating the above-mentioned comorbid disease conditions to attenuate inflammation and ONS and ameliorate decreased cerebral blood flow and hypometabolism. Additionally, several strategies are described here to control chronic hypoperfusion of the brain and enhance cognition. © 2016 Wiley Periodicals, Inc.

Bilateral common carotid artery stenosis in normotensive rats impairs endothelium-dependent dilation of parenchymal arterioles

Chronic cerebral hypoperfusion is a risk factor for cognitive impairment. Reduced blood flow through the common carotid arteries induced by bilateral carotid artery stenosis (BCAS) is a physiologically relevant model of chronic cerebral hypoperfusion. We hypothesized that BCAS in 20-wk-old Wistar-Kyoto (WKY) rats would impair cognitive function and lead to reduced endothelium-dependent dilation and outward remodeling in the parenchymal arterioles (PAs). After 8 wk of BCAS, both short-term memory and spatial discrimination abilities were impaired. In vivo assessment of cerebrovascular reserve capacity showed a severe impairment after BCAS. PA endothelial function and structure were assessed by pressure myography. BCAS impaired endothelial function in PAs, as evidenced by reduced dilation to carbachol. Addition of nitric oxide synthase and cyclooxygenase inhibitors did not change carbachol-mediated dilation in either group. Inhibiting CYP epoxygenase, the enzyme that produces epoxyeicosatrienoic acid (EETs), a key determinant of endothelium-derived hyperpolarizing factor (EDHF)-mediated dilation, abolished dilation in PAs from Sham rats, but had no effect in PAs from BCAS rats. Expression of TRPV4 channels, a target for EETs, was decreased and maximal dilation to a TRPV4 agonist was attenuated after BCAS. Together these data suggest that EET-mediated dilation is impaired in PAs after BCAS. Thus impaired endothelium-dependent dilation in the PAs may be one of the contributing factors to the cognitive impairment observed after BCAS.

Effect of exercise-induced neurogenesis on cognitive function deficit in a rat model of vascular dementia

Chronic cerebral hypoperfusion (CCH) is strongly correlated with progressive cognitive decline in neurological diseases, such as vascular dementia (VaD) and Alzheimer's disease. Exercise can enhance learning and memory, and delay age-related cognitive decline. However, exercise-induced hippocampal neurogenesis in experimental animals submitted to CCH has not been investigated. The present study aimed to investigate whether hippocampal neurogenesis induced by exercise can improve cognitive deficit in a rat model of VaD. Male Wistar rats (age, 8 weeks; weight, 292±3.05 g; n=12–13/group) were subjected to bilateral common carotid artery occlusion (2VO) or sham-surgery and each group was then subdivided randomly into no exercise and treadmill exercise groups. Exercise groups performed treadmill exercise daily at 15 m/min for 30 min for 4 weeks from the third to the seventh week after 2VO. It was demonstrated that the number of neural progenitor cells and mature neurons in the subgranular zone of 2VO rats was increased by exercise, and cognitive impairment in 2VO rats was attenuated by treadmill exercise. In addition, mature brain-derived neurotrophic factor (BDNF) levels in the hippocampus were increased in the exercise groups. Thus the present study suggests that exercise delays cognitive decline by the enhancing neurogenesis and increasing BDNF expression in the context of VaD.

Neuroprotective Effects of Electroacupuncture on an Animal Model of Bilateral Common Carotid Artery Occlusion

Mild cognitive impairment (MCI) is considered as an intermediate zone between normal aging and dementia. The most prominent feature of MCI is an isolated mild decline in memory, whereas other cognitive functions remain intact. The symptoms of vascular cognitive impairment (VCI) range from MCI to dementia, and an animal model of VCI has been established in a gerbil by transient bilateral common carotid artery occlusion (BCCAO). In the current study, we set out to investigate whether electroacupuncture (EA) could improve memory in gerbils with BCCAO-induced MCI. Animals were randomly divided into two groups: sham-operated group (n = 17) and a model group that was subdivided into BCCAO, n = 17, and EA-treated BCCAO, n = 28. Gerbils were treated with EA at KI3 or GV20 four times every other day using a set of electrical stimulus pulses (1 mA, 2 Hz) that were applied for 20 min. For investigation of cognitive function, we performed a Y-maze test and Western blotting to identify the expression of neuroinflammatory proteins. EA treatment at KI3 ("Taegye" acupoint) improved cognitive function and reduced the expression of neuroinflammatory proteins including ionized calcium-binding adaptor molecule 1, toll-like receptor 4, tumor necrosis factor alpha, and phospho-extracellular signal-regulated kinase in the hippocampus of gerbils that had undergone BCCAO. Furthermore, using micro-positron emission tomography/computed tomography, we demonstrated that EA treatment increased glucose metabolism in the hippocampus of these animals. The present study highlights the neuroprotective effect of EA treatment against BCCAO-induced memory dysfunction, neuroinflammation, and glucose metabolism. Our findings suggest that EA, which has previously been used in complementary and alternative medicine, might also be considered as a therapy that can improve memory and reduce neuroinflammation associated with dementia.

Resveratrol Reverses the Synaptic Plasticity Deficits in a Chronic Cerebral Hypoperfusion Rat Model

BACKGROUND

Dementia is the most prevalent neurological disease in aged people. Chronic cerebral hypoperfusion (CCH) is one of the causes of vascular dementia (VaD) and is also an etiological factor for Alzheimer's disease (AD). However, effective therapy for those two diseases is still missing. Resveratrol is a polyphenol produced by plants that have multiple biological functions, such as increased life span and delay in the onset of diseases associated with aging. It is known supplement with resveratrol could exert neuroprotection against multiple injury factors induced neuronal death and degeneration, as well as the cognitive decline of CCH rat model.

METHODS

The morris water maze was used to evaluate the learning and memory, electrophysiological recording was used to detect the synaptic plasticity, the Golgi staining was used to examine the change of dendritic spines, the western blot was used to detect the proteins levels.

RESULTS

We reported that resveratrol pretreatment effectively restore the synaptic plasticity in CCH rats both functional and structural. We also found that the PKA-CREB activation may be a major player in resveratrol-mediated neuroprotection in CCH model.

CONCLUSIONS

Our data provide the mechanistic evidence for the neuroprotective effects of resveratrol in vascular dementia.

Considerations for the Optimization of Induced White Matter Injury Preclinical Models

White matter (WM) injury in relation to acute neurologic conditions, especially stroke, has remained obscure until recently. Current advances in imaging technologies in the field of stroke have confirmed that WM injury plays an important role in the prognosis of stroke and suggest that WM protection is essential for functional recovery and post-stroke rehabilitation. However, due to the lack of a reproducible animal model of WM injury, the pathophysiology and mechanisms of this injury are not well studied. Moreover, producing selective WM injury in animals, especially in rodents, has proven to be challenging. Problems associated with inducing selective WM ischemic injury in the rodent derive from differences in the architecture of the brain, most particularly, the ratio of WM to gray matter in rodents compared to humans, the agents used to induce the injury, and the location of the injury. Aging, gender differences, and comorbidities further add to this complexity. This review provides a brief account of the techniques commonly used to induce general WM injury in animal models (stroke and non-stroke related) and highlights relevance, optimization issues, and translational potentials associated with this particular form of injury.

Effect of modified Bo-yang-Hwan-o-Tang, a polyherbal medicine on the hippocampal neuronal damage in a rat model of global ischemia

Background:

Chronic cerebral hypoperfusion has been well-characterized as a common pathological status contributing to vascular dementia (VD). In this study, the neuroprotective effect of modified Bo-yang-Hwan-O Tang (mBHT), a polyherbal medicine for ischemic stroke, was investigated in a rat model for global ischemia.

Materials and Methods:

Global ischemia model was prepared in Sprague-Dawley rats by the permanent occlusion of bilateral common carotid arteries (two-vessel occlusion [2VO])-induced chronic cerebral hypoperfusion. mBHT at doses of 250 and 500 mg/kg was orally administrated for 4 weeks once a day, 24 h after 2VO. Histopathological change of the hippocampal region was observed by hematoxylin and eosin, Nissl, and Fluoro-Jade B staining and immunohistochemistry with anti-glial fibrillary acidic protein and anti-neuronal nuclei antibodies. The expression of Bax, Bcl-2, and caspase-3 was investigated in the hippocampus by Western blot. The nuclear factor-kappa B (NF-κB) expression was also analyzed in hippocampal CA1 region using immunofluorescence staining.

Results:

The administration of mBHT at doses of 250 and 500 mg/kg significantly inhibited chronic cerebral hypoperfusion-induced neuronal damage and astroglial activation in the hippocampal CA1 region in 2VO rats. mBHT increased the NF-κB expression in the CA1 neuronal cells but decreased in activated astrocytes. In addition, mBHT significantly decreased the hippocampal expression of Bax and caspase-3 and increased the Bcl-2 expression in 2VO rats.

Conclusions:

Our data indicate that mBHT has a neuroprotective property in VD induced by chronic cerebral hypoperfusion through inhibiting the hippocampal neuronal damage and astrogliosis.

Protective effect of Daming capsule against chronic cerebral ischemia

Background

Accumulating evidence has shown that chronic cerebral ischemia (CCI) is one of the major causes of vascular dementia (VD) characterized by dysregulated cholesterol homeostasis and lipoprotein disturbances. Positive value of lipid-lowering agents has been widely evaluated for the treatment of VD. In the present study, we investigated whether Daming capsule (DMC) protected against CCI-induced VD and its possible mechanisms of action. DMC is a multi-herbal formula composed of Rheum palmatum L., Cassia obtusifolia L., Salvia miltiorrhiza, and Panax ginseng C.A., which has been used to treat hyperlipidemia for years in China.

Methods

A network pharmacology method was established to reveal whether DMC contained any chemical constituent targeting CCI-related proteins. Furthermore, the potential anti-CCI effects of DMC (100 mg/kg or 200 mg/kg) administered for 30 days were investigated in vivo on rats that were subjected to permanent bilateral occlusion of the carotid arteries (2-VO). Spatial learning and memory abilities were evaluated using a Morris water maze (MWM) and morphological changes of cerebral cortex and hippocampus were assessed using hematoxylin and eosin staining. Moreover, the lipid peroxidation levels and antioxidative capabilities were measured using biochemical analysis.

Results

Our network pharmacology analysis revealed the existence of multiple CCI-related chemical-target interactions in DMC, suggesting a potential protective effect. An in vivo experiment verified that 200 mg/kg DMC improved cognitive deficits of 2-VO rats in the MWM test and attenuated pathological alterations in both the cerebral cortex and the hippocampus. Biochemical assays indicated that DMC decreased malondialdehyde levels and CCI-elevated superoxide dismutase activities, but increased the activities of glutathione peroxidase and catalase.

Conclusions

Our findings suggested that DMC protected against cognitive dysfunction and nerve injuries caused by CCI, which is most likely related to its antioxidant actions.

Salidroside prevents cognitive impairment induced by chronic cerebral hypoperfusion in rats

OBJECTIVE

To investigate the effects of salidroside on cognitive dysfunction induced by chronic cerebral hypoperfusion in rats.

METHODS

Male Sprague-Dawley rats (n = 36) were divided into three groups (n = 12 per group): sham operation; bilateral permanent occlusion of the common carotid arteries (2-VO); 2-VO + salidroside. Rats received 20 mg/kg per day salidroside or vehicle intraperitoneal injection beginning the day before surgery and continuing until 34 days postoperatively. Cognitive function was evaluated by Morris water maze test and hippocampal long-term potentiation (LTP) measurement. Hippocampal neuronal apoptosis was evaluated via immunofluorescence.

RESULTS

Chronic cerebral hypoperfusion caused marked cognitive deficit and LTP inhibition. These effects were largely ameliorated by salidroside administration. Salidroside prevented caspase-3 activation, increased the ratio of Bax/Bcl-2, and reversed hippocampal neuronal loss induced by chronic cerebral hypoperfusion.

CONCLUSIONS

Salidroside prevents cognitive deficits caused by chronic cerebral hypoperfusion in rats, and alleviates apoptosis in the hippocampal CA1 area.

(2R,3S)-Pinobanksin-3-cinnamate improves cognition and reduces oxidative stress in rats with vascular dementia

This study investigated the neuroprotective effects of (2R,3S)-pinobanksin-3-cinnamate (PNC) in rats with occlusion-damaged bilateral common carotid arteries. Administration with PNC (5 and 10 mg/kg/day) for 5 weeks significantly improved the behavioral performance of rats with vascular dementia, as showed in the Morris water maze test by shortening the escape latency and latency of crossing, completing more platform crossings, as well as spending more time in the target zone. Further evaluations found that PNC could markedly decrease malondialdehyde levels, enhance superoxide dismutase activity and glutathione levels, and decrease the release of cytochrome c as well as the activities of caspases. Moreover, PNC increased Nrf2 and anti-apoptotic bcl-2 protein expression, while Nox1 and pro-apopotic bax protein expression was decreased. PNC may exert its neuroprotective effects through counteracting oxidative stress and has the potential to treat vascular dementia.

Bilateral common carotid artery occlusion induced brain lesions in rats: A longitudinal diffusion tensor imaging study

Bilateral common carotid artery occlusion (BCCAO) has been widely used to reproduce the white matter (WM) and gray matter (GM) damage associated with chronic cerebral hypoperfusion (CCH). This study investigated whether diffusion tensor imaging (DTI) could be used at the early stages of disease to assess brain damage induced by BCCAO. To this end, DTI, together with histological methods, was used to evaluate the progression of WM lesions and GM neurodegeneration following BCCAO. The DTI was sufficiently sensitive to detect WM abnormalities in selected regions of the brain at 4weeks after BCCAO. These abnormalities may indicate damage to the myelin and axons in the optic nerve (ON) and optic tract (OT). Our longitudinal results showed that DTI could be used to detect abnormalities of the WM and GM in select regions of the brain as early as 2days after ligation. The DTI parameter patterns of change were region-specific throughout the detection time course. Lesions of the external capsule (EC) and periventricular hypothalamic nucleus (Pe) have not been thoroughly studied before. We found that the EC and Pe were both vulnerable to BCCAO and that the associated lesions could be detected using DTI. The current study demonstrated that in vivo DTI could potentially be used to measure WM damage evolution in a BCCAO rat model as well as early brain injury following CCH.

The neuroprotection of repetitive transcranial magnetic stimulation pre-treatment in vascular dementia rats

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive technique that could interfere cortical excitability though brief electric currents induced by alternating magnetic fields from the inductive coil. Currently, it has been applied in many fields of basic and clinical neuro-research. The aims of the present study are to investigate the effect of rTMS pre-treatment on cognitive function in vascular dementia (VaD) rats and further explore the molecular mechanism of rTMS neuroprotection on VaD. We found that rTMS pre-treated VaD rats showed significantly better memory and learning abilities in Morris water maze test compared to the untreated group. Moreover, the mRNA and protein expression levels of BDNF, TrkB, and SYN were significantly higher in the rTMS pre-treated group, indicating that rTMS pre-treatment has neuroprotective effect for VaD, which may have resulted from the increased level of BDNF, TrkB, and SYN in the hippocampal CA1 area.

A cognitive rehabilitation paradigm effective in male rats lacks efficacy in female rats

Cognitive dysfunction, as a consequence of dementia, is a significant cause of morbidity lacking efficacious treatment. Females comprise at least half of this demographic but have been vastly underrepresented in preclinical studies. The current study addressed this gap by assessing the protective efficacy of physical exercise and cognitive activity on learning and memory outcomes in a rat model of vascular dementia. Forty ovariectomized Sprague-Dawley rats (∼6 months old) were exposed to either a diet high in saturated fats and refined sugars or standard laboratory chow and underwent either chronic bilateral carotid occlusion or Sham surgery. Learning and memory abilities were evaluated using standard cognitive outcomes over the ensuing 6 months, followed by histologic analyses of hippocampal CA1 neurons. In Experiment 1, we confirmed hypoperfusion-induced cognitive dysfunction using a 2 × 2 (Surgery × Diet) experimental design, without alterations in hippocampal architecture. In Experiment 2, hypoperfused animals were either exposed to alternating days of physical (wheel running) and cognitive activity (modified Hebb-Williams maze) or sedentary housing. In contrast to males, this combination rehabilitation paradigm did not improve cognition or histopathologic outcomes in hypoperfused animals. These findings, highlighting differences between female and male animals, show the necessity of including both sexes in preclinical experimentation.