2VO Surgery Research Articles

Profiling hippocampal expression of long non-coding RNA GM12371 in a rat model of vascular dementia

BackgroundDementia, characterized by synaptic dysfunction and memory loss, presents a significant challenge in medical research. Long non-coding RNAs (lncRNAs), known for their crucial roles in regulating gene expression, represent a gap in knowledge regarding their specific involvement in synaptic structure, transmission, and plasticity. This study aims to investigate the dynamic changes in hippocampal lncRNA GM12371 expression in response to acute and chronic hypoperfusion in the rat brain using the 2VO model.MethodsThe 2VO model was induced by permanently occluding the common carotid arteries. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to evaluate hippocampal lncRNA GM12371 expression at both acute (day 4) and chronic (day 28) stages post-2VO surgery. Comparative analysis was conducted with a sham-operated group.ResultsA notable reduction in GM12371 expression was observed in the rat hippocampus on day 4 following 2VO surgery compared to the sham group (P < 0.05). However, there was no significant difference in GM12371 expression between the sham and 2VO-28 groups.ConclusionThese findings suggest that the downregulation of GM12371 is a response to acute hippocampal blood flow reduction but tends to normalize during the chronic phase of cerebral hypoperfusion. This dynamic regulation of GM12371 expression may be significant in the adaptive response to vascular dementia. Further clinical studies are warranted to investigate potential peripheral alterations in GM12371 expression in individuals with dementia.

Taohong Siwu decoction alleviates cognitive impairment by suppressing endoplasmic reticulum stress and apoptosis signaling pathway in vascular dementia rats

Ethnopharmacological relevanceTaohong Siwu Decoction (TSD), a classic traditional Chinese medicine formula, is used for the treatment of vascular diseases, including vascular dementia (VD). However, the mechanisms remain unclear. Aim of studyThis study aimed to investigate whether TSD has a positive effect on cognitive impairment in VD rats and to confirm that the mechanism of action is related to the Endoplasmic Reticulum stress (ERs) and cell apoptosis signaling pathway. Materials and methodsA total of 40 male adult Sprague-Dawley rats were divided into four groups: sham-operated group (Sham), the two-vessel occlusion group (2VO), the 2VO treated with 4.5 g/kg/d TSD group (2VO + TSD-L), the 2VO treated with 13.5 g/kg/d TSD group (2VO + TSD-H). The rats underwent either 2VO surgery or sham surgery. Postoperative TSD treatment was given for 4 consecutive weeks. Behavioral tests were initiated at the end of gastrulation. Open-field test (OFT) was used to detect the activity level. The New Object Recognition test (NOR) was used to test long-term memory. The Morris water maze (MWM) test was used to examine the foundation of spatial learning and memory. As a final step, the hippocampus was taken for molecular testing. The protein levels of GRP78 (Bip), p-PERK, PERK, IRE1α, p-IRE1α, ATF6, eIF2α, p-eIF2α, ATF4, XBP1, Bcl-2 and Bax were determined by Western blot. Immunofluorescence visualizes molecular expression. ResultsIn the OFT, residence time in the central area was significantly longer in both TSD treatment groups compared to the 2VO group. In the NOR, the recognition index was obviously elevated in both TSD treatment groups. The 2VO group had a significantly longer escape latency and fewer times in crossing the location of the platform compared with the Sham group in MWM. TSD treatment reversed this notion. Pathologically, staining observations confirmed that TSD inhibited hippocampal neuronal loss and alleviated the abnormal reduction of the Nissl body. In parallel, TUNEL staining illustrated that TSD decelerated neuronal apoptosis. Western Blot demonstrated that TSD reduces the expression of ERs and apoptotic proteins. ConclusionIn this study, the significant ameliorative effect on cognitive impairment of TSD has been determined by comparing the behavioral data of the 4 groups of rats. Furthermore, it was confirmed that this effect of TSD was achieved by suppressing the ERs-mediated apoptosis signaling pathway.

Acrobatic training prevents motor deficits and neuronal loss in male and female rats following chronic cerebral hypoperfusion

BackgroundChronic cerebral hypoperfusion in vascular dementia leads to memory and motor deficits; Physical exercise improves these aspects and promotes neuroprotection. Sexual dimorphism may significantly influence both ischemic and exercise outcomes. AimsThe aim of this study was to investigate the effects of 2VO (Two-Vessel occlusion) and the acrobatic training on motor function, functional performance, and tissue loss in male and female rats. MethodsMale and female rats were randomly divided into 4 groups: sham acrobatic, sham sedentary, 2VO acrobatic and 2VO sedentary. After 45 days of 2VO surgery, the animals received 4 weeks of acrobatic training. At the end, open field, beam balance and horizontal ladder tests were performed. Brain samples were taken for histological and morphological evaluation. ResultsSpontaneous motor activity in the open field was not affected by 2VO, on the other hand, an impairment in forelimb placement was observed after 2VO and acrobatic training prevented errors and improved hindlimb placement. Neuronal loss was found in the motor cortex and striatum after 2VO, especially in females, which was prevented by acrobatic training. ConclusionMild motor damage was found in animals after 2VO when refined movement was evaluated, probably associated to neuronal death in the motor cortex and striatum. The acrobatic exercise showed a neuroprotective effect, promoting neuronal survival and attenuating the motor deficit.

The environmental enrichment ameliorates chronic cerebral hypoperfusion-induced cognitive impairment by activating autophagy signaling pathway and improving synaptic function in hippocampus

BackgroundChronic cerebral hypoperfusion (CCH) is a frequently observed underlying pathology of both Alzheimer's disease (AD) and vascular dementia (VD), which is a common consequence of cerebral blood flow (CBF) dysregulation. Synaptic damage has been proven as a crucial causative factor for CCH-related cognitive impairment. This study aimed to investigate the neuroprotective impact of environmental enrichment (EE) intervention on CCH-induced synaptic destruction and the consequent cognitive impairment. Furthermore, the underlying mechanism of this neuroprotective effect was explored to provide new insights into therapeutic interventions for individuals suffering from AD or VD. MethodsIn this experiment, all rats were initially acclimatized to a standard environment (SE) for a period of one week. On the seventh day, rats underwent either bilateral common carotid artery occlusion (2VO) surgery or sham surgery (Sham) before being subjected to a four-week procedure of exposure to an EE, except for the control group. During the EE or SE procedure, intraperitoneal injection of chloroquine (CQ) into rats was performed once daily for four weeks. Following this, cognitive function was assessed using the Morris water maze (MWM) test. The synapse ultrastructure was subsequently observed using transmission electron microscopy. Expression levels of autophagy-related proteins (LC3, LAMP1, and P62) and synapse-related proteins (Synapsin I and PSD-95) were detected through Western blotting. Finally, immunofluorescence was used to examine the expression levels of Synapsin I and PSD-95 and the colocalization of LAMP-1 and LC3 in the hippocampus. ResultsAfter undergoing 2VO, rats exposed to SE exhibited cognitive impairment, autophagic dysfunction, and synapse damage. The synapse damage was evidenced by ultrastructural damage and degradation of synapse-related proteins. However, these effects were significantly mitigated by exposure to an EE intervention. Moreover, the intervention led to an improvement in autophagic dysfunction. ConclusionThe study found that EE had a positive impact on CCH-induced synaptic damage. Specifically, EE was found to increase synaptic plasticity-associated proteins and postsynaptic density thickness, while decreasing synaptic space. This multifaceted effect resulted in an amelioration of CCH-induced cognitive impairment. It was shown that this beneficial outcome was mediated via the activation of the autophagy-lysosomal pathway. Overall, the findings suggest that EE may have a therapeutic potential for cognitive impairments associated with CCH through autophagy-mediated synaptic improvement.

Higher Circulating Trimethylamine N-Oxide Aggravates Cognitive Impairment Probably via Downregulating Hippocampal SIRT1 in Vascular Dementia Rats.

Oxidative stress and inflammation damage play pivotal roles in vascular dementia (VaD). Trimethylamine N-oxide (TMAO), an intestinal microbiota-stemming metabolite, was reported to promote inflammation and oxidative stress, involved in the etiology of several diseases. Still, these effects have not been investigated in VaD. Here, we tested whether pre-existing, circulating, high levels of TMAO could affect VaD-induced cognitive decline. TMAO (120 mg/kg) was given to rats for a total of 8 weeks, and these rats underwent a sham operation or bilateral common carotid artery (2VO) surgery after 4 weeks of treatment. Four weeks after surgery, the 2VO rats exhibited hippocampal-dependent cognitive function declines and synaptic plasticity dysfunction, accompanied by an increase in oxidative stress, neuroinflammation, and apoptosis. TMAO administration, which increased plasma and hippocampal TMAO at 4 weeks postoperatively, further aggravated these effects, resulting in exaggerated cognitive and synaptic plasticity impairment, though not within the Sham group. Moreover, TMAO treatment activated the NLRP3 inflammasome and decreased SIRT1 protein expression within the hippocampus. However, these effects of TMAO were significantly attenuated by the overexpression of SIRT1. Our findings suggest that TMAO increases oxidative stress-induced neuroinflammation and apoptosis by inhibiting the SIRT1 pathway, thereby exacerbating cognitive dysfunction and neuropathological changes in VaD rats.

Resveratrol reduces inflammatory response and detrimental effects in chronic cerebral hypoperfusion by down-regulating stimulator of interferon genes/TANK-binding kinase 1/interferon regulatory factor 3 signaling.

Inflammatory responses induced by chronic cerebral hypoperfusion (CCH) play a critical role in the progression of vascular dementia. Stimulator of interferon genes (STING) signaling function as a key mediator of inflammation and immunological responses in the central nervous system (CNS), and resveratrol (RES) exerts potent anti-inflammatory effects. However, the role of STING signaling and the relationship between RES and STING signaling in persistent hypoperfusion-induced cerebral inflammation remain unclear. In this study, Sprague–Dawley rats were subjected to either Sham or bilateral common carotid artery occlusion (2VO) surgery and received RES or vehicle daily by intraperitoneal injection for 4 or 8 weeks. Morris’s water maze was used for the analysis of cognitive function. The neuroinflammatory responses in white matter and hippocampus of the rat brain were assessed by Western blot, Immunofluorescence staining, and qRT-PCR analyses. Myelin integrity, neutrophil infiltration, and microglia proliferation were assessed by Immunohistochemistry and histologic analysis. We demonstrated that after CCH, neurons, microglia, and astrocyte under endoplasmic reticulum (ER) stress upregulated the expression of STING, TANK-binding kinase 1 (TBK1), and the transcription factor interferon regulatory factor 3 (IRF3), as well as translocation of IRF3 into the nucleus. These were accompanied by infiltration of neutrophils, activation of microglia, and overproduction of proinflammatory mediators. Improvements in cognitive deficits were related to reduced hippocampal neuronal cell death and increased myelin integrity in RES-treated rats. The neuroprotective effects of RES were associated with suppression of the expression of tumor necrosis factor-alpha (TNF-α), intercellular adhesion molecule 1 (ICAM-1), VCAM-1, interferon-β (IFN-β), and IL-1β, likely through mitigation of the STING/TBK1/IRF3 pathway. These inhibitory effects exerted by RES also inhibited the levels of myeloperoxidase, reduced excess expression of reactive astrocytes, and activated microglia. In conclusion, the STING/TBK1/IRF3 axis may be critical for proinflammatory responses in cerebral tissue with persistent hypoperfusion, and RES exerts its anti-inflammatory effects by suppressing STING/TBK1/IRF3 signaling.

Depressive-like behaviors induced by chronic cerebral hypoperfusion associate with a dynamic change of GABAB1/B2 receptors expression in hippocampal CA1 region

Cerebral ischemia could induce depressive-like behaviors; however, the alteration of gamma-aminobutyric acid receptors type B (GABAB) receptors in these pathological processes has not been extensively investigated. The aim of the current study was to document the behavioral change and the alteration of GABAB receptors in chronic cerebral hypoperfusion. The permanent occlusion of the bilateral common carotid arteries (two-vessel occlusion, 2VO) was performed to induce chronic cerebral ischemia (CCH). The depressive-like behaviors were evaluated with sucrose preference test, novelty suppress feeding test as well as forced swim test at 4, 8, and 12 weeks after the 2VO surgery. The total, surface and intracellular expressions of GABAB subunit 1 (GABAB1) and subunit 2 (GABAB2) in hippocampal CA1 were quantified by western blot. The depressive-like behaviors were observed in rats suffered from 4, 8, and 12 weeks 2VO in sucrose preference test, novelty suppress feeding test and forced swim test. In addition, the surface and total expression of GABAB1 in CA1 was reduced at 4 weeks after 2VO rather than 8 or 12 weeks. While the surface and total expression of GABAB2 in CA1 was decreased throughout the ischemia timeline (4, 8, and 12 weeks). Taken together, our findings suggested the potential roles of GABAB1 and GABAB2 subunits involved in depressive-like behaviors caused by chronic cerebral hypoperfusion.

Adalimumab ameliorates memory impairments and neuroinflammation in chronic cerebral hypoperfusion rats.

Vascular dementia (VaD) is the second most common type of dementia worldwide. Although there are five FDA-approved drugs for the treatment of Alzheimer’s disease (AD), none of them have been applied to treat VaD. Adalimumab is a TNF-α inhibitor that is used for the treatment of autoimmune diseases such as rheumatoid arthritis. In a recent retrospective case-control study, the application of adalimumab for rheumatoid or psoriasis was shown to decrease the risk of AD. However, whether adalimumab can be used for the treatment of VaD is not clear. In this study, we used 2VO surgery to generate a VaD rat model and treated the rats with adalimumab or vehicle. We demonstrated that VaD rats treated with adalimumab exhibited significant improvements in memory. In addition, adalimumab treatment significantly alleviated neuronal loss in the hippocampi of VaD rats. Moreover, adalimumab significantly reduced microglial activation and reversed M1/M2 polarization in VaD rats. Furthermore, adalimumab treatment suppressed the activity of NF-κB, an important neuroinflammatory transcription factor. Finally, adalimumab displayed a protective role against oxidative stress in VaD rats. Our results indicate that adalimumab may be applied for the treatment of human patients with VaD.

Effects of imperatorin on apoptosis and synaptic plasticity in vascular dementia rats

In view of the complicated pathophysiological process of vascular dementia (VD), drugs for the clinical treatment of VD mainly target related risk factors, while drugs with excellent efficacy in cognitive function are still relatively lacking. Imperatorin (IMP), an active constituent extracted from angelica dahuricae and notopterygium Notopterygii, which has anti-inflammatory, vasodilator, anticoagulant, block calcium channel, anticonvulsant, and anti oxygen free radical injury properties. Therefore,the present study examined its effects on VD rats and the underlying molecular mechanisms, in order to provide promising therapeutic methods. VD was established by modified ligation of perpetual two-vessel occlusion (2VO). After 2VO surgery, IMP (2.5, 5, and 10 mg/kg) was administered by intraperitoneal injection for 12 consecutive weeks to evaluate therapeutic effects. Cognitive function was verified by the Morris water maze. The neuronal morphological changes were examined via Hematoxylin–Eosin staining. Real-Time PCR and Western blot were used for detecting pro- and antiapoptotic biomarkers, and the hippocampus synaptic damage was examined by Transmission electron microscope. We revealed that 2VO-induced cognitive impairment, hippocampus CA1 neuron damage, apoptosis and synaptic damage. IMP-treatment significantly improved 2VO-induced cognitive deficits and hippocampus neuron damage. Molecular analysis revealed that IMP inhibited apoptosis through the down regulation of Bax, Caspase-3 and upregulation of Bcl-2. Meanwhile, IMP-treatment markedly improved synaptic ultrastructure morphology, increased the SAZ length, PSD thickness and up-regulated PSD-95 expression. Collectively, our findings demonstrated that IMP was effective in the treatment of 2VO-induced VD via inhibiting apoptosis of hippocampus neurons and reducing the synaptic plasticity destroy.

Physical exercise modulates the astrocytes polarization, promotes myelin debris clearance and remyelination in chronic cerebral hypoperfusion rats

AimsWhite matter damage is the main pathological feature of chronic cerebral hypoperfusion (CCH) and glial activation is crucial in this process. Physical exercise has protective effects on CCH, but the mechanism is unclear. Therefore, this study focuses on investigating the influence of physical exercise on activated astrocytes polarization and its role in CCH. Main methodsRats were given wheel running 48 h after 2VO (2 vessel occlusion) surgery. The cognitive function was evaluated by Morris water maze and novel object recognition test. Inflammatory cytokines expressions were detected by ELISA. Astrocytes polarization was analyzed by immunofluorescence. Myelin debris clearance and remyelination were detected by immunofluorescence and transmission electron microscopy. Key findingsAstrocytes were activated and mainly switched to A1 phenotype in rats 2 and 3 months after 2VO. Myelin debris deposition and limited remyelination can be observed at the corresponding time. Whereas physical exercise can improve the cognitive function of 2VO rats, downregulate the expression of inflammatory factors IL-1α, C1q and TNF, upregulate the release of TGFβ, and promote activated astrocytes transformation from A1 to A2 phenotype. In addition, it can also enhance myelin debris removal and remyelination. SignificanceThese findings suggest that the benefits of physical exercise on white matter repair and cognition improvement may be related to its regulation of astrocytes polarization, which contributes to myelin debris clearance and effective remyelination in CCH.

Limb Remote Ischemic Conditioning Ameliorates Cognitive Impairment in Rats with Chronic Cerebral Hypoperfusion by Regulating Glucose Transport.

Cognitive impairment is closely associated with the slowing of glucose metabolism in the brain. Glucose transport, a rate-limiting step of glucose metabolism, plays a key role in this phenomenon. Previous studies have reported that limb remote ischemic conditioning (LRIC) improves cognitive performance in rats with chronic cerebral hypoperfusion (CCH). Here, we determined whether LRIC could ameliorate cognitive impairment in rats with CCH by regulating glucose transport. A total of 170 male Sprague-Dawley rats were used. Animals subjected to permanent double carotid artery occlusion (2VO) were assigned to the control or LRIC treatment group. LRIC was applied beginning 3 days after the 2VO surgery. We found that LRIC can improve learning and memory; decrease the ratio of ADP/ATP; increase glucose content; upregulate the expression of pAMPKα, GLUT1 and GLUT3; and increase the number of GLUT1 and GLUT3 transporters in cerebral cortical neurons. The expression of GLUT1 and GLUT3 in the cortex displayed a strong correlation with learning and memory. Pearson correlation analysis showed that the levels of GLUT1 and GLUT3 are correlated with neurological function scores. All of these beneficial effects of LRIC were ablated by application of the AMPK inhibitor, dorsomorphin. In summary, LRIC ameliorated cognitive impairment in rats with CCH by regulating glucose transport via the AMPK/GLUT signaling pathway. We conclude that AMPK-mediated glucose transport plays a key role in LRIC. These data also suggest that supplemental activation of glucose transport after CCH may provide a clinically applicable intervention for improving cognitive impairment.

Epimedium flavonoids protect neurons and synapses in the brain via activating NRG1/ErbB4 and BDNF/Fyn signaling pathways in a chronic cerebral hypoperfusion rat model

Cerebral hypoperfusion is a common feature of cerebral small vascular disease (CSVD), which has been considered as one of the causes of cognitive decline in recent years. Epimedium flavonoids (EF) are the main ingredients extracted from Epimedium. The purpose of this study was to investigate the effects of EF on cognitive impairment, and the underlying mechanisms in rats with permanent occlusion of the bilateral common carotid artery (2VO). EF (50, 100, and 200 mg/kg) was intragastrically administered for 12 weeks starting 2 weeks after 2VO surgery. The results showed that EF treatment improved learning and memory impairment in 2VO rats evaluated by novel object recognition and Y-maze tests. NeuN immunohistochemical staining indicated that EF alleviated neuronal loss in the hippocampus and cerebral cortex of 2VO rats. MAP-2 immunofluorescence staining and western blotting showed that EF protected neuronal dendrites and increased the expression of cytoskeleton proteins MAP-2 and NF200 in the hippocampus of 2VO rats. Moreover, EF protected the synapse ultrastructure detected by transmission electron microscopy, and increased the expression of synaptic plasticity-related proteins, including synaptophysin, synaptotagmin-I, synapsin I, PSD-95, p-NMDA2B, and p-CaMKII-α in the hippocampus of 2VO rats. In addition, EF increased the expression of neuregulin-1 (NRG-1), p-ErbB4, brain-derived neurotrophic factor (BDNF), p-Fyn, PI3K, p-Akt, and p-CREB in the hippocampus of 2VO rats. These results suggest that EF may protect neurons and synapses by activating the NRG1/ErbB4, BDNF/Fyn, and P13 K/Akt/CREB pathways in the hippocampus and cerebral cortex, thus improving cognitive impairment induced by chronic cerebral hypoperfusion. EF may be a potential candidate drug for chronic cerebral hypoperfusion and CSVD therapy.

Epimedium flavonoids improve cognitive impairment and white matter lesions induced by chronic cerebral hypoperfusion through inhibiting the Lingo-1/Fyn/ROCK pathway and activating the BDNF/NRG1/PI3K pathway in rats

Chronic cerebral hypoperfusion is a common cause of cerebral small vascular disease (CSVD). White matter (WM) lesions are the typical pathological manifestation of CSVD and contribute to cognitive decline. Epimedium flavonoids (EF) are the main component in Epimedium brevicornu Maxim., which is commonly used in traditional Chinese medicine. The purpose of this study was to investigate the effects of EF on cognitive impairment and the underlying mechanisms in a CSVD rat model induced with chronic cerebral hypoperfusion. The model was established by permanent bilateral common carotid artery occlusion (2VO) in rats. EF (50, 100, and 200 mg/kg) was intragastrically administered once a day for 12 weeks starting 2 weeks after 2VO surgery. The learning and memory capacity of the rats were measured using the Morris water maze and step-through tests. WM lesions were observed by MRI-diffusion tensor imaging, transmission electron microscopy, and LFB staining. Oligodendrocytes were detected by immunohistochemistry. Western blotting assay was used to determine the level of protein expression. The results showed that EF significantly improved learning and memory impairment, alleviated WM nerve fiber injuries and demyelination, and increased the number of mature oligodendrocytes in the corpus callosum, subcortical WM, and periventricular WM in 2VO rats. Mechanistically, EF reduced the expression of Lingo-1 and ROCK2 and increased the levels of phosphorylated (p-) Fyn, brain-derived neurotrophic factor (BDNF), TrkB, neuregulin-1 (NRG-1), p-ErbB4, PI3K p85 and p110α, p-Akt, and p-CREB in the corpus callosum of 2VO rats. These results suggest that EF may improve cognitive impairment and WM lesions induced by chronic cerebral hypoperfusion through inhibiting the Lingo-1/Fyn/ROCK pathway and activating the BDNF/TrkB, NRG-1/ErbB4, and the downstream PI3K/Akt/CREB pathways in WM. Thus, EF can be used as a potential neuroprotective agent in CSVD therapy.

Physical exercise promotes astrocyte coverage of microvessels in a model of chronic cerebral hypoperfusion

BackgroundBrain circulation disorders such as chronic cerebral hypoperfusion have been associated with a decline in cognitive function during the development of dementia. Astrocytes together with microglia participate in the immune response in the CNS and make them potential sentinels in the brain parenchyma. In addition, astrocytes coverage integrity has been related to brain homeostasis. Currently, physical exercise has been proposed as an effective intervention to promote brain function improvement. However, the neuroprotective effects of early physical exercise on the astrocyte communication with the microcirculation and the microglial activation in a chronic cerebral hypoperfusion model are still unclear. The aim of this study was to investigate the impact of early intervention with physical exercise on cognition, brain microcirculatory, and inflammatory parameters in an experimental model of chronic cerebral hypoperfusion induced by permanent bilateral occlusion of the common carotid arteries (2VO).MethodsWistar rats aged 12 weeks were randomly divided into four groups: Sham-sedentary group (Sham-Sed), Sham-exercised group (Sham-Ex), 2VO-sedentary group (2VO-Sed), and 2VO-exercised group (2VO-Ex). The early intervention with physical exercise started 3 days after 2VO or Sham surgery during 12 weeks. Then, the brain functional capillary density and endothelial-leukocyte interactions were evaluated by intravital microscopy; cognitive function was evaluated by open-field test; hippocampus postsynaptic density protein 95 and synaptophysin were evaluated by western blotting; astrocytic coverage of the capillaries, microglial activation, and structural capillary density were evaluated by immunohistochemistry.ResultsEarly moderate physical exercise was able to normalize functional capillary density and reduce leukocyte rolling in the brain of animals with chronic cerebral hypoperfusion. These effects were accompanied by restore synaptic protein and the improvement of cognitive function. In addition, early moderate exercise improves astrocytes coverage in blood vessels of the cerebral cortex and hippocampus, decreases microglial activation in the hippocampus, and improves structural capillaries in the hippocampus.ConclusionsMicrocirculatory and inflammatory changes in the brain appear to be involved in triggering a cognitive decline in animals with chronic cerebral ischemia. Therefore, early intervention with physical exercise may represent a preventive approach to neurodegeneration caused by chronic cerebral hypoperfusion.

MicroRNA-153 impairs presynaptic plasticity by blocking vesicle release following chronic brain hypoperfusion

BackgroundChronic brain hypoperfusion (CBH) is closely related to Alzheimer’s disease (AD) and vascular dementia (VaD). Meanwhile, synaptic pathology plays a prominent role in the initial stage of AD and VaD. However, whether and how CBH impairs presynaptic plasticity is currently unclear.MethodsIn the present study, we performed a battery of techniques, including primary neuronal culture, patch clamp, stereotaxic injection of the lentiviral vectors, morris water maze (MWM), dual luciferase reporter assay, FM1–43 fluorescence dye evaluation, qRT-PCR and western blot, to investigate the regulatory effect of miR-153 on hippocampal synaptic vesicle release both in vivo and in vitro. The CBH rat model was generated by bilateral common carotid artery ligation (2VO).ResultsCompared to sham rats, 2VO rats presented decreased field excitatory postsynaptic potential (fEPSP) amplitude and increased paired-pulse ratios (PPRs) in the CA3-CA1 pathway, as well as significantly decreased expression of multiple vesicle fusion-related proteins, including SNAP-25, VAMP-2, syntaxin-1A and synaptotagmin-1, in the hippocampi. The levels of microRNA-153 (miR-153) were upregulated in the hippocampi of rats following 2VO surgery, and in the plasma of dementia patients. The expression of the vesicle fusion-related proteins affected by 2VO was inhibited by miR-153, elevated by miR-153 inhibition, and unchanged by binding-site mutation or miR masks. FM1–43 fluorescence images showed that miR-153 blunted vesicle exocytosis, but this effect was prevented by either 2′-O-methyl antisense oligoribonucleotides to miR-153 (AMO-153) and miR-masking of the miR-153 binding site in the 3′ untranslated region (3’UTR) of the Snap25, Vamp2, Stx1a and Syt1 genes. Overexpression of miR-153 by lentiviral vector-mediated miR-153 mimics (lenti-pre-miR-153) decreased the fEPSP amplitude and elevated the PPR in the rat hippocampus, whereas overexpression of the antisense molecule (lenti-AMO-153) reversed these changes triggered by 2VO. Furthermore, lenti-AMO-153 attenuated the cognitive decline of 2VO rats.ConclusionsOverexpression of miR-153 controls CBH-induced presynaptic vesicle release impairment by posttranscriptionally regulating the expression of four vesicle release-related proteins by targeting the 3’UTRs of the Stx1a, Snap25, Vamp2 and Syt1 genes. These findings identify a novel mechanism of presynaptic plasticity impairment during CBH, which may be a new drug target for prevention or treatment of AD and VaD.E8TH8SFpmLGUrZnTkkAYxHVideo Graphical abstract

Abstract WMP78: The Efficacy of Angiotensin II Peptide Vaccination Against White Matter Lesions of Vascular Dementia in Rats

Background &amp; Purposes: There had been no attempt to show the efficacy of therapeutic vaccination in vascular dementia. A rat model of vascular dementia was prepared by bilateral common carotid artery ligation (2VO). The purpose of this study is to investigate whether pre-exposure Angiotensin II (Ang II) peptide vaccination exhibits the protective effects against white matter lesions (WML) in 2VO rats. Methods: After subcutaneous injection of Ang II peptide vaccine (10μg/200μl) or saline (200μl) to Wistar rats (male) at the time point of 6, 8 and 10 week-old, 2VO or sham surgery was performed at 12 week-old. Cognitive function was evaluated after 14 days of 2VO using the novel object recognition (NOR) test. Anti-Ang II antibody (Ab) level was quantified using ELISA. Histological examinations of WML and demyelination in the corpus callosum (CC) were evaluated using immunohistochemistry (IHC), 5-bromodeoxyuridine (BrdU) assay and Klüver-Barrera staining. Western blot analyses of VCAM-1, FGF2, phospho-CREB and CREB using proteins extracted from CC were performed to investigate the mechanism of restoration of WML by Ang II vaccination. Results: Histological examinations presented that exacerbation of WML and demyelination observed in saline treated (S) rats was ameliorated in Ang II vaccinated (V) rats. The results of NOR test indicated that cognitive dysfunction observed in S rats was improved in V rats at 14 days after 2VO. Expression of VCAM-1 in CC of S rats was significantly reduced in V rats at 7 days after 2VO. BrdU assay exhibited that vaccination accelerated the differentiation of oligodendrocyte progenitor cells (OPCs) in WML from 14 days to 28 days of 2VO. Western blot presented that both CREB phosphorylation and FGF2 expression in CC were increased in V rats compared with S rats at 14 days after 2VO. Double IHC showed that FGF2 expressing cells were mostly endothelial cells and astrocytes in WML. Conclusions: Ang II vaccination restored WML as well as cognitive function in 2VO rats. Our findings suggested that Ang II vaccination ameliorated cerebrovascular endothelial dysfunction which could accelerate the OPCs differentiation through increased expression of FGF2 in endothelial cells or astrocytes in 2VO rats.

Influence of metabolic syndrome on cerebral perfusion and cognition

Vascular cognitive impairment (VCI) is associated with chronic cerebral hypoperfusion (CCH) and memory deficits, and often occurs concurrently with metabolic syndrome (MetS). Despite their common occurrence, it is unknown whether CCH and MetS act synergistically to exacerbate VCI-associated pathology. Here, using male Sprague-Dawley rats, we examined the effects of a clinically relevant model of adolescent-onset MetS and adult-onset CCH on neuro-vascular outcomes, combining a cafeteria diet with a 2-vessel occlusion (2VO) model. Using longitudinal imaging, histology, and behavioural assessments, we identified several features of MetS and CCH including reduced cerebral blood volume, white matter atrophy, alterations in hippocampal cell density, and memory impairment. Furthermore, we identified a number of significant associations, potentially predictive of MetS and pathophysiological outcomes. White matter volume was positively correlated to HDL cholesterol; hippocampal cell density was negatively correlated to fasted blood glucose; cerebral blood flow and volume was negatively predicted by the combination of 2VO surgery and increased fasted blood glucose. These results emphasize the importance of including comorbid conditions when modeling VCI, and they outline a highly translational preclinical model that could be used to investigate potential interventions to mitigate VCI-associated pathology and cognitive decline.

Cornel iridoid glycoside improves cognitive impairment induced by chronic cerebral hypoperfusion via activating PI3K/Akt/GSK-3β/CREB pathway in rats

Chronic cerebral hypoperfusion is an important risk factor for vascular dementia (VaD) and other brain dysfunctions, for which there are currently no effective medications available. In the present study, we investigated the potential therapeutic effects of cornel iridoid glycoside (CIG) on VaD in rats modeled by permanent bilateral common carotid artery ligation (2-vessel occlusion, 2VO). The object recognition test (ORT) and Morris water maze (MWM) test were conducted to evaluate the learning and memory function. Western blot analysis and immunohistochemical staining were used to detect the expression of related proteins. Results showed that intragastric administration of CIG (30, 60, and 120 mg/kg) for 3 months significantly increased the discrimination index in ORT and decreased the escape latency in MWM test, ameliorating the learning and memory deficit in 2VO rats. Further data indicated that CIG increased the expression of neurotrophic factors (NGF and BDNF) and their receptors (TrkA and TrkB), glutamate receptor subunits (NMDAR1 and GluR2) in the cerebral cortex and hippocampus of 2VO rats. In addition, CIG elevated the expression of PI3K subunits p110α and p85, further upregulated the phosphorylation of Akt, GSK3β-ser9 and CREB in the cerebral cortex and hippocampus at 3 months after 2VO surgery. Collectively, CIG treatment improved learning and memory deficit induced by chronic cerebral hypoperfusion via increasing neurotrophic factors thus protecting glutamate receptors and activating PI3K/Akt/GSK3β/CREB signaling pathway in rats. These results suggest that CIG may be beneficial to VaD therapy.

Efficacy of a low-dose melatonin pretreatment in protecting against the neurobehavioral consequences of chronic hypoperfusion in middle-aged female rats

Mild cognitive impairment (MCI) is characterized by a reduction in cerebral blood flow. Permanent ligation of the common carotid arteries (2VO) in the rat mimics the chronic decrease in CBF that characterizes aMCI. The current study determined if melatonin (a pineal hormone with neuroprotective properties) can attenuate the neurobehavioral consequences of 2VO using middle-aged female rats. Two weeks following 2VO or sham surgery, rats were tested on various learning and memory tasks. 2VO resulted in hyperlocomotion on the open field. Melatonin attenuated this 2VO-induced hyperactivity. 2VO impaired visual memory however this was not attenuated by melatonin administration. Neither 2VO nor melatonin affected spatial memory performance on the MWM or spatial recognition task. Y-maze testing revealed 2VO rats exhibited a lower spontaneous alternation pattern and performed a greater number of alternate arm returns compared to 2VO rats treated with melatonin. 2VO resulted in a significant loss of CA1 hippocampal neurons which was attenuated with melatonin treatment. Chronic melatonin was found to attenuate the neuronal consequences of chronic cerebral hypoperfusion but only conferred partial behavioral protection in middle-aged female rats. Our results demonstrate that inclusion of older rodents is important in neuroprotection studies as neuroprotective agents may act differently in an aged brain.

Neuroprotective Effect of Oral Administration of Trigonella Foenum-Graecum on Chronic Cerebral Hypoperfusion in Rat Model

Introduction: Decreased cerebral blood supply to the brain can generate a condition of chronic cerebral hypoperfusion, which is one of the pathophysiological mechanisms of neuronal degeneration and cognitive impairment in Alzheimer’s disease. This study aimed to evaluate the potential neuroprotective effects of Trigonella foenum graecum seeds on chronic cerebral hypoperfusion in a rat model. Materials and Methods: Chronic cerebral hypoperfusion was induced by permanent bilateral ligation of the common carotid arteries (a two-vessel occlusion, 2VO) in male Sprague–Dawley rats. The experimental groups were divided into three groups (11 rats/group): i) sham (control) group; ii) 2VO group without any treatment; and iii) 2VO group that was administered orally with the Trigonella foenum graecum extract (100 mg/kg/day) by oral gavage from 3 days before the date of 2VO surgery and continued daily until the end of the 8th postoperative week. Spatial memory performance was assessed by the Morris water maze test. Malondialdehyde and C-reactive protein (CRP) concentration, superoxide dismutase and glutathione activities were measured in serum after 8 weeks from 2VO injury. Results: Chronic cerebral hypoperfusion rats resulted in spatial memory impairments. This behavioral dysfunction was accompanied by decreasing superoxide dismutase and glutathione activities, and increasing malondialdehyde and CRP levels in serum. Oral administration of Trigonella foenum graecum extract significantly improved the memory impairment, enhanced antioxidant enzyme activities, and decreased the malondialdehyde and CRP levels to near normal levels. Conclusion: The potential activity offered by Trigonella foenum graecum extract showed the neuroprotective effect that may be beneficial in cerebrovascular type dementia.