Validation of a preclinical animal model to assess brain recovery after acute stroke

Establishment of a pMCAO model in SD rats and screening for behavioral indicators suitable for long-term monitoring

OBJECTIVE

This study aimed to establish a permanent middle cerebral artery occlusion (pMCAO) model in rats to simulate the pathological process of stroke patients with no reperfusion. And screen highly sensitive items that could be used to detect long-term behavioral abilities in rat of intraluminal suture models.

METHOD

Established the pMCAO model then tested the rats for the bilateral asymmetry, modified neurological severity score, grid-walking, cylinder, rotating, and water maze test from week 1 to week 16.

RESULTS

The infarct volume of the model rats was stable (26.72% ±1.86%). The sensorimotor test of bilateral asymmetry, grid-walking, cylinder, and mNSS test showed significant differences from week 1 to week 16 after injury. The water maze test at week 16 showed significant differences in spatial exploration and learning ability between the two groups. We confirmed that there was no significant difference between MRI and TTC staining in detecting the degree of brain injury, which facilitated the diversity of subsequent detection methods. We also confirmed that at multiple time points, grid, cylinder and water maze test were significantly positively correlated with rat brain infarct volume.

CONCLUSION

They are suitable for the long-term observation of behaviors in the sequela stage of stroke in rat.

Protective effect and mechanism of styrax on ischemic stroke rats: metabonomic insights by UPLC-Q/TOF-MS analysis

CONTEXT

Styrax is used for prevention and treatment of cerebrovascular diseases. However, the underlying mechanism remains unclear.

OBJECTIVE

To elucidate styrax's anti-ischemic stroke protective effects and underlying mechanisms.

MATERIALS AND METHODS

An ischemic-stroke rat model was established based on middle cerebral artery occlusion (MCAO). Sprague-Dawley rats were randomly assigned to the following groups (n = 10) and administered intragastrically once a day for 7 consecutive days: sham, model, nimodipine (24 mg/kg), styrax-L (0.1 g/kg), styrax-M (0.2 g/kg) and styrax-H (0.4 g/kg). Neurological function, biochemical assessment, and ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q/TOF-MS)-based serum metabonomics were used to elucidate styrax's cerebral protective effects and mechanisms. Pearson correlation and western blot analyses were performed to verify.

RESULTS

The addition of 0.4 g/kg styrax significantly reduced cerebral infarct volume and neurobehavioral abnormality score. Different doses of styrax also decrease MDA, TNF-α, IL-6, and IL-1β, and increase SOD and GSH-Px in ischemic-stroke rats (p < 0.05; MDA, p < 0.05 only at 0.4 g/kg dose). Biochemical indicators and metabolic-profile analyses (PCA, PLS-DA, and OPLS-DA) also supported styrax's protective effects. Endogenous metabolites (22) were identified in ischemic-stroke rats, and these perturbations were reversible via styrax intervention, which is predominantly involved in energy metabolism, glutathione and glutamine metabolism, and other metabolic processes. Additionally, styrax significantly upregulated phosphorylated AMP-activated protein kinase and glutaminase brain-tissue expression.

CONCLUSION

Styrax treatment could ameliorate ischemic-stroke rats by intervening with energy metabolism and glutamine metabolism. This can help us understand the mechanism of styrax, inspiring more clinical application and promotion.

Pre exposure to enriched environment alleviates brain injury after ischemia-reperfusion by inhibiting p38MAPK/STAT1 pathway

BACKGROUND

Stroke is one of the major diseases that endangers human health. It is widely reported that enriched environment (EE) can improve the neurological function in different brain injury models. Recently, relevant researches have indicated that MAPK pathway is closely related to the inflammatory response in nervous system related diseases. However, whether pre exposure to EE (EE pretreatment) has a preventive effect, and its mechanism are not clear. Therefore, this study aimed to determine the possible benefits and related mechanisms of EE in preventing brain injury after acute ischemia-reperfusion.

METHODS

Adult Sprague Dawley rats were kept in enriched or standardized environments for 21 days. Then the middle cerebral artery of rats was occluded for one hour and 30 min, and then reperfusion was performed. Then their neurological deficit score was evaluated. Cerebral edema, along with ELISA and protein quantities of p38MAPK, JNK, ERK, IL-1β, TNF-α, and co-localization of Iba1 were assessed. Changes in neuroinflammation and apoptosis were also detected in the penumbra cortex.

RESULTS

Our research showed that EE pretreatment significantly alleviated acute cerebral ischemia-reperfusion injury in rats. Including the reduction of brain edema and apoptosis, and the improvement of neurological scores. In addition, the protein level of p38MAPK was significantly down regulated in EE pretreatment group, and the downstream protein STAT1 had the same trend. In addition, immunofluorescence results showed that Iba1 in EE pretreatment group decreased, the ELISA results showed that the classical proinflammatory cytokines increased significantly, while anti-inflammatory cytokines in EE pretreatment group increased, and the same results were obtained by Western blot analysis.

CONCLUSION

On the whole, our research demonstrated that EE pretreatment can have a protective effect on the organism by inhibiting the p38 MAPK/STAT1 pathway. Thus, EE can be one of the most promising means of disease prevention. Secondly, p38MAPK/STAT1 pathway may be a latent target for the prevention of acute ischemic stroke.

Analysis of differential gene expression profiles uncovers mechanisms of Xuesaitong injection against cerebral ischemia-reperfusion injury

BACKGROUND

Xuesaitong injection (XST), a well-known traditional Chinese patent medicine, has been widely used in the treatment of cardiovascular and cerebrovascular diseases. The exact mechanisms of XST in ischemic stroke remain to be thoroughly elucidated.

PURPOSE

This study aims to characterize the candidate differentially expressed genes (DEGs) and pathways of XST in ischemic stroke by bioinformatics analysis, and to explore new clues for the underlying mechanisms of XST.

METHODS

A dataset (GSE61616) was performed to screen out DEGs for deep analysis. Series Test of Cluster analysis for DEGs was carried out. For all DEGs, Gene Ontology (GO) annotation analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed for visualization. The screened hub gene expression characteristics were verified in middle cerebral artery occlusion (MCAO) rats. In vivo studies have demonstrated the mechanisms of XST against cerebral ischemia-reperfusion (CIR) injury.

RESULTS

A total of 8066 DEGs were screened out and the expression of genes in profile 8 was suggested to have clinical significance. The MAPK signaling pathway was indicated as the most significantly enriched pathway in profile 8. Bdnf was identified as the most significant hub gene according to node degree. Animal experiments demonstrated that XST attenuated CIR injury. XST increased brain-derived neurotrophic factor (BDNF) and its high-affinity receptor tropomyosin-related kinase B (TrkB) levels in MCAO. Furthermore, the knockdown of BDNF by siRNA abolished the in vivo effects of XST on brain injury, neurodegeneration and apoptosis after CIR.

CONCLUSION

The integrated strategy, based on bioinformatics analyses with experimental verification, provides a novel cellular mechanism by which XST alleviates CIR injury. The BDNF-TrkB pathway was highly thought to play a vital role in the neuroprotective effects of XST.

An Optimal Animal Model of Ischemic Stroke Established by Digital Subtraction Angiography-Guided Autologous Thrombi in Cynomolgus Monkeys

Objective

Ischemic stroke seriously threatens human health, characterized by the high rates of incidence, disability, and death. Developing a reliable animal model that mimics most of the features of stroke is critical for pathological studies and clinical research. In this study, we aimed to establish and examine a model of middle cerebral artery occlusion (MCAO) guided by digital subtraction angiography (DSA) in cynomolgus monkeys.

Materials and Methods

In this study, 15 adult male cynomolgus monkeys were enrolled. Under the guidance of DSA, a MCAO model was established by injecting an autologous venous clot into the middle cerebral artery (MCA) via femoral artery catheter. Thrombolytic therapy with alteplase (rt-PA) was given to eight of these monkeys at 3 h after the occlusion. Blood test and imaging examination, such as computed tomography angiography (CTA), CT perfusion (CTP), brain magnetic resonance imaging (MRI), and brain magnetic resonance angiography (MRA), were performed after the operation to identify the post-infarction changes. The behavioral performance of cynomolgus monkeys was continuously observed for 7 days after operation. The animals were eunthanized on the 8th day after operation, and then the brain tissues of monkeys were taken for triphenyltetrazolium chloride (TTC) staining.

Results

Among the 15 cynomolgus monkeys, 12 of them were successfully modeled, as confirmed by the imaging findings and staining assessment. One monkey died of brain hernia resulted from intracranial hemorrhage confirmed by necropsy. DSA, CTA, and MRA indicated the presence of an arterial occlusion. CTP and MRI showed acute focal cerebral ischemia. TTC staining revealed infarct lesions formed in the brain tissues.

Conclusion

Our study may provide an optimal non-human primate model for an in-depth study of the pathogenesis and treatment of focal cerebral ischemia.

Beta-Boswellic Acid Protects Against Cerebral Ischemia/Reperfusion Injury via the Protein Kinase C Epsilon/Nuclear Factor Erythroid 2-like 2/Heme Oxygenase-1 Pathway

Ischemic strokes are associated with a high rate of disability and death globally. Cerebral ischemia/reperfusion (I/R) injury is a type of brain damage associated with oxidative stress after an ischemic stroke. Beta-boswellic acid (β-BA) reportedly exerts antioxidant and neuroprotective effects, but its role in cerebral I/R injury is unclear. The aim of this research was to investigate the neuroprotective effects, as well as the mechanisms of β-BA in cerebral I/R injury. In vivo experiments were conducted using a rat middle cerebral artery occlusion and reperfusion (MCAO/R) model, and in vitro experiments were performed using a rat neuronal oxygen-glucose deprivation and reoxygenation (OGD/R) model. Triphenyltetrazolium chloride staining, neurological function scores, terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling, hematoxylin and eosin staining, and antioxidant levels in the brain were used to assess the effects of β-BA. Flow cytometry was used to detect reactive oxygen species and apoptotic cells. Western blotting and immunofluorescence staining were used to measure protein levels. The results showed that β-BA markedly improved neurological deficits and decreased infarct volume and necrotic neurons in rats. The in vitro results showed that β-BA protected neurons against OGD/R-induced injury. Additionally, β-BA significantly increased the phosphorylation of protein kinase C epsilon (PRKCE) at S729, the translocation of nuclear factor erythroid 2-like 2 (NFE2L2), and expression of heme oxygenase-1 (HMOX1). This study demonstrates that β-BA exerts neuroprotective effects against cerebral I/R via the activation of the PRKCE/NFE2L2/HMOX1 pathway and is a potential therapeutic candidate for ischemic stroke.

Therapeutic effects of JLX-001 on ischemic stroke by inducing autophagy via AMPK-ULK1 signaling pathway in rats

(3β,5α,16α,20S)-4,4,14-trimethyl-3,20-bis(methylamino)-9,19-cyclopregnan-16-ol-dihydrochloride (JLX-001), a structural analogue of cyclovirobuxine D (CVB-D), is a novel compound from synthesis. This study aims to confirm the therapeutic effects of JLX001 on ischemic stroke (IS) and research its induction of autophagy function via 5'-AMP-activated protein kinase (AMPK)-Human Serine/threonine-protein kinase (ULK1) signaling pathway activation. The therapeutic effects of JLX001 were evaluated by infarct sizes, brain edema, neurological scores and proportion of apoptotic neurons in Sprague-Dawley (SD) rats with middle cerebral artery occlusion/reperfusion (MCAO/R). The number of autophagosomes was obtained by transmission electron microscopy. The expression of LC3-II was measured by immunofluorescence. p-AMPK and activated ULK1 were detected by western blots. Results showed that JLX001 treatment markedly alleviated cerebral infarcts, edema, neurological scores and proportion of apoptotic neurons in MCAO/R rats. The number of autophagosomes was increased, accompanying with the increased expressions of LC3-II, p-AMPK and ULK1. In summary, JLX001 attenuates cerebral ischemia injury and the underlying mechanisms may relate to inducing autophagy via AMPK-ULK1 signaling pathway activation.