Correlation between cerebral blood flow and histologic changes in a new rat model of middle cerebral artery occlusion

Regulation of blood-brain barrier integrity by brain microvascular endothelial cells in ischemic stroke: A therapeutic opportunity

Stroke is the second leading cause of death from cardiovascular diseases. Brain microvascular endothelial cells (BMECs) are crucial in the treatment of cerebral ischemic stroke, as their functional status directly affects the integrity of the blood-brain barrier (BBB). This review systematically discusses the central role of BMECs in ischemia. The mitochondrial dysfunction and activation of apoptosis/necrosis pathways in BMECs directly disrupt the integrity of the BBB and the degradation of junctional complexes (such as TJs and AJs) further exacerbates its permeability. In the neurovascular unit (NVU), astrocytes, microglia, and pericytes regulate the function of BMECs by secreting cytokines (such as TGF-β and VEGF), showing dual effects of promoting repair and damage. The dynamic changes of transporters, including those from the ATP-binding cassette and solute carrier families, as well as ion channels and exchangers, such as potassium and calcium channels, offer novel insights for the development of targeted drug delivery systems.

Deacetylation of nuclear AIF provides a braking mechanism for caspase-independent chromatinolysis and necrotic brain injury

Programmed necrosis involves three consecutive stages: initiation, propagation, and execution. The initiation of necrosis has been widely studied, but due to the diversity and pleiotropy of the initiating pathways, it is difficult to identify ideal targets for necrosis inhibition from upstream necrosis pathways. Genetic evidence suggests that caspase-independent chromatinolysis, an execution process in multiple forms of necrosis, could be targeted to inhibit necrosis, but its regulatory mechanisms remain unclear. Previous studies suggest that the apoptosis-inducing factor AIF promotes chromatinolysis and caspase-independent necrosis, and its cytosol-to-nucleus translocation induces irreversible chromatinolysis. Here we report that AIF acetylation at lysine 295 is required for its cytosol-to-nucleus translocation and conduction of caspase-independent chromatinolysis upon necrotic stimuli, the SIRT1 deacetylase blocks necrotic chromatinolysis via deacetylating AIF, and pharmacological activation of SIRT1 inhibits AIF-dependent chromatinolysis and necrotic brain injury. Our results reveal a reversible blocking mechanism for AIF-dependent chromatinolysis and caspase-independent necrosis, supporting that targeting the late necrosis stage is a promising therapeutic strategy for treatment of necrosis-associated diseases.

Amygdalin's neuroprotective effects on acute ischemic stroke in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Amygdalin, a key component of Peach kernel (semen persicae), also known as Taoren, is a traditional Chinese herb known for promoting blood circulation and alleviating blood stasis, especially in stroke treatment. This study aimed to explore the effects of amygdalin on neurological function in a rat model of acute ischemic stroke.

METHODS

We induced acute ischemic stroke in Sprague-Dawley rats by occluding the right middle cerebral artery (MCAO) for 30 min, followed by reperfusion. Amygdalin was administered intraperitoneally at doses of 5 mg, 10 mg, and 20 mg per kilogram starting 24 h post-reperfusion for three consecutive days. We assessed cerebral infarct volume and neurological function, and analyzed the brain tissue using western blotting.

RESULTS

Amygdalin significantly reduced cerebral infarct volume resulting from MCAO in the 5-mg group (amygdalin 5 mg/kg; 18.02 ± 7.51 %), 10-mg group (amygdalin 10 mg/kg; 16.25 % ± 6.35 %) and 20-mg group (amygdalin 20 mg/kg; 12.26 ± 6.69 %) compared to the sham group (phosphate buffer saline; 28.99 ± 6.36 %) (all p < 0.001). The 10-mg and 20-mg groups showed significantly lower modified neurological severity scores (mNSS) than the sham group 5 days post-reperfusion (p < 0.05, p < 0.0001, respectively). Performance on the rotarod test also improved significantly in the 10-mg group (p < 0.05) and 20-mg group (p < 0.0001) compared to the sham group, and the distance traveled in the open-field test increased significantly in the 5-mg group (p < 0.001), 10-mg group (p < 0.0001) and 20-mg group (p < 0.0001) compared to the sham group. Western blotting revealed that the expression of uncleaved caspase-3 in the cerebral cortex was greater in the sham group compared to the control (without MCAO and treatment) and the 20-mg groups (both p < 0.05), while the expression of caspase-9 was greater in the control and 20-mg groups than in the sham group (both p < 0.05).

CONCLUSION

Intraperitoneal administration of amygdalin for three days reduced cerebral infarct volume and improved neurological function in a rat model of acute ischemic stroke. Additionally, amygdalin decreased uncleaved caspase-3 expression and increased caspase-9 expression. The findings suggest that amygdalin plays a neuroprotective role through modulation of apoptosis process via the intrinsic pathway.

Elemene mitigates oxidative stress and neuronal apoptosis induced by cerebral ischemia-reperfusion injury through the regulation of glutathione metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Chinese materia medica (CMM) has a long history and extensive experience in treating ischemic stroke. Wen Ezhu, the rhizome of Curcuma wenyujin Y.H. Chen et C. Ling, is renowned for promoting blood circulation, dispersing blood stasis, alleviating pain, and eliminating masses. Promoting blood circulation and removing blood stasis are essential principles in Traditional Chinese Medicine for treating stroke. Consequently, Wen Ezhu is frequently used in clinical practice as a key CMM for treating stroke. The Elemene active fraction (ELE), a sesquiterpene compound extracted from Wen Ezhu, primarily consists of β-Elemene. It also contains β-Caryophyllene, γ-Elemene, and δ-Elemene isomers. ELE has shown potential pharmacological effects in various diseases, including ischemic stroke. However, its precise mechanism of action in treating stroke remains to be confirmed.

AIM OF THE STUDY

To explore the therapeutic potential of ELE in acute ischemic stroke and elucidate its underlying mechanisms.

MATERIALS AND METHODS

A rat model of middle cerebral artery occlusion reperfusion (MCAO/R) was used to evaluate ELE's effects. Therapeutic efficacy was assessed through mNSS scoring, magnetic resonance imaging (MRI), tetrazolium chloride (TTC) staining, Hematoxylin and eosin (H&E), and Nissl staining. Non-targeted metabolomics identified key pathways, confirmed using biochemical analysis, immunohistochemistry, and Western blotting. ROS levels and apoptosis-related proteins were also evaluated.

RESULTS

Our findings show that ELE administration significantly reduced the cerebral infarct area and lowered modified neurological severity scores (mNSS) in animals, indicating a strong neuroprotective effect. Metabolomics results highlight the glutathione (GSH) metabolic pathway as a key mechanism through which ELE exerts its therapeutic effects. Specifically, ELE upregulates glutathione reductase (GR) protein expression and downregulates glutathione peroxidase (GPX) expression. The regulatory process of ELE decreases oxidized glutathione (GSSG) levels and increases GSH levels, effectively reducing oxidative stress damage (lower reactive oxygen species levels) during CI/RI. This results in the downregulation of the pro-apoptotic protein Bax and the upregulation of the pro-survival protein Bcl-2, thus reducing neuronal apoptosis.

CONCLUSIONS

ELE protects neurons in MCAO/R rats through the GSH metabolism pathway, balancing GSH and GSSG levels to mitigate oxidative stress and enhance neuroprotection in cerebral ischemia/reperfusion injury.

Rhynchophylline promotes microglia phenotypic transformation and repair of cerebral ischaemic injury through the JAK2/STAT3 pathway

BACKGROUND

Rhynchophylline (RIN) is an alkaloid known for its ability to effectively block signal transduction related to various neurodegenerative diseases. However, the specific mechanism by which RIN regulates microglial activation and cerebral ischemia remains unexplored. This study aims to investigate the function and molecular pathways through which RIN activates the JAK2/STAT3 signaling cascade, promoting the transformation of microglial phenotypes that contribute to recovery from cerebral ischemic injury.

METHODS

By establishing a microglia oxygen glucose deprivation/reoxygenation (OGD/R) model and a middle cerebral artery occlusion animal model, we assessed changes in the expression of phenotype-specific marker factors for M1 and M2 microglia, as well as key proteins in the JAK2/STAT3 pathway, utilizing ELISA and Western blot techniques. Histological examination, including HE staining, TUNEL assay, and immunofluorescence, was employed to evaluate pathological changes in brain tissue, along with cell apoptosis and proliferation.

RESULTS

The results indicated that microglial activity was significantly reduced and shifted towards the M1 phenotype following OGD/R. However, RIN treatment reversed these changes. When JAK2/STAT3 inhibitors were combined with RIN, it inhibited RIN's protective effect. Animal studies have shown that RIN reduces histopathological changes associated with cerebral ischemia. Additionally, RIN inhibited microglial proliferation in ischemic cortical tissue and increased the expression of M2-type marker proteins, as well as the levels of phosphorylated JAK2 and STAT3 in the ischemic tissue.

CONCLUSION

In conclusion, this study indicates that RIN may protect against cerebral ischemic injury by activating the JAK2/STAT3 pathway, which promotes the transition of microglia to the M2 phenotypic.

A crosstalk between autophagy and apoptosis in intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a severe condition that devastatingly harms human health and poses a financial burden on families and society. Bcl-2 Associated X-protein (Bax) and B-cell lymphoma 2 (Bcl-2) are two classic apoptotic markers post-ICH. Beclin 1 offers a competitive architecture with that of Bax, both playing a vital role in autophagy. However, the interaction between Beclin 1 and Bcl-2/Bax has not been conjunctively analyzed. This review aims to examine the crosstalk between autophagy and apoptosis in ICH by focusing on the interaction and balance of Beclin 1, Bax, and Bcl-2. We also explored the therapeutic potential of Western conventional medicine and traditional Chinese medicine (TCM) in ICH via controlling the crosstalk between autophagy and apoptosis.

TMEM79 Ameliorates Cerebral Ischemia/Reperfusion Injury Through Regulating Inflammation and Oxidative Stress via the Nrf2/NLRP3 Pathway

BACKGROUND

Cerebral ischemia/reperfusion injury (CIRI) is still a complicated disease with high fatality rates worldwide. Transmembrane Protein 79 (TMEM79) regulates inflammation and oxidative stress in some other diseases.

METHODS

CIRI mouse model was established using C57BL/6J mice through middle cerebral artery occlusion-reperfusion (MCAO/R), and BV2 cells were subjected to oxygen and glucose deprivation/reoxygenation (OGD/R) to simulate CIRI. Brain tissue or BV2 cells were transfected or injected with lentivirus-carried TMEM79 overexpression vector. The impact of TMEM79 on CIRI-triggered oxidative stress was ascertained by dihydroethidium (DHE) staining and examination of oxidative stress indicators. Regulation of TMEM79 in neuronal apoptosis and inflammation was determined using TUNEL staining and ELISA.

RESULTS

TMEM79 overexpression mitigated neurological deficit induced by MCAO/R and decreased the extent of cerebral infarct. TMEM79 prevented neuronal death in brain tissue of MCAO/R mouse model and suppressed inflammatory response by reducing inflammatory cytokines levels. Moreover, TMEM79 significantly attenuated inflammation and oxidative stress caused by OGD/R in BV2 cells. TMEM79 facilitated the activation of Nrf2 and inhibited NLRP3 and caspase-1 expressions. Rescue experiments indicated that the Nrf2/NLRP3 signaling pathway mediated the mitigative effect of TMEM79 on CIRI in vivo and in vitro.

CONCLUSION

Overall, TMEM79 was confirmed to attenuate CIRI via regulating the Nrf2/NLRP3 signaling pathway.

Expression and metabolism profiles of CVT associated with inflammatory responses and oxygen carrier ability in the brain

AIM

As the main type of stroke, the incidence of cerebral venous thrombosis (CVT) has been rising. However, the comprehensive mechanisms behind it remain unclear. Thus, the multi-omics study is required to investigate the mechanism after CVT and elucidate the characteristic pathology of venous stroke and arterial stroke.

METHODS

Adult rats were subjected to CVT and MCAO models. Whole-transcriptome sequencing (RNA-seq) and untargeted metabolomics analysis were performed to construct the transcriptome and metabolism profiles of rat brains after CVT and also MCAO. The difference analysis, functional annotation, and enrichment analysis were also performed.

RESULTS

Through RNA-seq analysis, differentially expressed genes (DEGs) were screened. 174 CVT specific genes including Il1a, Ccl9, Cxxl6, Tnfrsf14, etc., were detected. The hemoglobin genes, including both Hba and Hbb, were significantly downregulated after CVT, compared both to the MCAO and Sham groups. Metabolism analysis showed that CVT had higher heterogeneity of metabolism compared to MCAO. Metabolites including N-stearoyltyrosine, 5-methoxy-3-indoleaceate, Afegostat, pipecolic acid, etc. were specially regulated in CVT. Through the immune infiltration analysis, it was found that CVT had a higher immune response, with the abundance of certain types of immune cells increased, especially T helper cells. It was important to find the prevalence of the activation of inflammatory chemokine, cytokine, NOD-like pathway, and neutrophil extracellular trap.

CONCLUSION

We explored and analyzed the gene expression and metabolomic characteristics of CVT, revealed the specific inflammatory reaction mechanism of CVT and found the markers in transcriptome and metabolism levels. It points out the direction for CVT early diagnosis and treatment.

Bicarbonate signalling via G protein-coupled receptor regulates ischaemia-reperfusion injury

Homoeostatic regulation of the acid-base balance is essential for cellular functional integrity. However, little is known about the molecular mechanism through which the acid-base balance regulates cellular responses. Here, we report that bicarbonate ions activate a G protein-coupled receptor (GPCR), i.e., GPR30, which leads to Gq-coupled calcium responses. Gpr30-Venus knock-in mice reveal predominant expression of GPR30 in brain mural cells. Primary culture and fresh isolation of brain mural cells demonstrate bicarbonate-induced, GPR30-dependent calcium responses. GPR30-deficient male mice are protected against ischemia-reperfusion injury by a rapid blood flow recovery. Collectively, we identify a bicarbonate-sensing GPCR in brain mural cells that regulates blood flow and ischemia-reperfusion injury. Our results provide a perspective on the modulation of GPR30 signalling in the development of innovative therapies for ischaemic stroke. Moreover, our findings provide perspectives on acid/base sensing GPCRs, concomitantly modulating cellular responses depending on fluctuating ion concentrations under the acid-base homoeostasis.

FNDC5 inhibits autophagy of bone marrow mesenchymal stem cells and promotes their survival after transplantation by downregulating Sp1

Regenerative therapy based on mesenchymal stem cells (MSCs) has great promise to achieve functional recovery in cerebral infarction patients. However, the survival rate of transplanted MSCs is extremely low because of destructive autophagy caused by the harsh ischemic microenvironment in cerebral infarct tissue. The mechanism by which fibronectin type III domain protein 5 (FNDC5) regulates autophagy of transplanted bone marrow-MSCs (BMSCs) following ischemic injury needs to be elucidated. In this study, we confirmed that FNDC5 promotes the survival of transplanted BMSCs in a rat cerebral infarction model. Furthermore, bioinformatic analysis and verification experiments revealed the transcription factor, Sp1, to be a key mediator of autophagy regulation by FNDC5. FNDC5 significantly inhibited BMSC autophagy by down-regulating Sp1 and the autophagy-related Sp1-target gene, ULK2. Transplanted BMSCs overexpressing FNDC5 (BMSCs-OE-FNDC5) promoted neurovascular proliferation and alleviated ischemic brain injury in cerebral infarct model rats. However, the increased survival and enhanced neuroprotective effect of transplanted BMSCs-OE-FNDC5 were reversed by simultaneous overexpression of Sp1. Our data indicate a role for FNDC5 in BMSC survival and reveal a novel mechanism of transcription regulation through Sp1 for the autophagy-related gene ULK2. Modulation of FNDC5 may promote survival capacity and improve the therapeutic effect of BMSCs in various tissues following ischemia.

Substance P Reduces Infarct Size and Mortality After Ischemic Stroke, Possibly Through the M2 Polarization of Microglia/Macrophages and Neuroprotection in the Ischemic Rat Brain

Substance-P (SP) is an 11 amino acid neuropeptide that is known to stimulate the peripheral mobilization of bone marrow mesenchymal stem cells and M2 polarization in monocytes/macrophages in a variety of acute and chronic tissue injuries. To examine the role of SP in protection and recovery from acute ischemic brain injury, experimental ischemic stroke was induced by transient middle cerebral artery occlusion (tMCAo) in rats for 1 h with subsequent reperfusion. Two injections of SP, immediately and one day post-tMCAo, resulted in approximately threefold lower mortality and 40% less infarct volume than those of saline-treated rats at seven days post-tMCAo. At 4.5 h, SP markedly increased CD11b/c+CD163+/CD 206+ cells in the blood, which were concomitantly decreased in the bone marrow, suggesting that SP preferentially mobilized M2-polarized monocytes. After two days, SP increased the expression of neuroprotective and anti-inflammatory genes in the ischemic brain and induced neuronal survival in the brain penumbra. Additionally, SP markedly increased CD68+CD163+ and CD68+CD206+ M2 microglia/macrophages in the ischemic brain during seven days post-tMCAo. Furthermore, SP preserved the blood‒brain barrier in the ischemic brain, which was confirmed by the abundant levels of SMI71+ brain endothelial cells that colocalized with α-SMA+ pericytes. The beneficial effects of SP on functional recovery and tissue preservation were maintained for six weeks. Collectively, SP treatment in the early phase of ischemic stroke markedly suppressed the destructive inflammatory response and improved the microenvironment for tissue protection and repair.

Temporary Occlusion of Common Carotid Arteries Does Not Evoke Total Inhibition in the Activity of Corticospinal Tract Neurons in Experimental Conditions

Temporary occlusion of the common cervical artery is the reason for ischemic stroke in 25% of patients. Little data is provided on its effects, especially regarding neurophysiological studies verifying the neural efferent transmission within fibers of the corticospinal tract in experimental conditions. Studies were performed on 42 male Wistar rats. In 10 rats, ischemic stroke was evoked by permanent occlusion of the right carotid artery (group A); in 11 rats, by its permanent bilateral occlusion (B); in 10 rats, by unilateral occlusion and releasing after 5 min (C); and in 11 rats, by bilateral occlusion and releasing after 5 min (D). Efferent transmission of the corticospinal tract was verified by motor evoked potential (MEP) recordings from the sciatic nerve after transcranial magnetic stimulation. MEPs amplitude and latency parameters, oral measurements of temperature, and verification of ischemic effects in brain slides stained with hematoxylin and eosin staining (H + E) were analyzed. In all groups of animals, the results showed that five minutes of uni- or bilateral occlusion of the common carotid artery led to alterations in brain blood circulation and evoked changes in MEP amplitude (by 23.2% on average) and latency parameters (by 0.7 ms on average), reflecting the partial inability of tract fibers to transmit neural impulses. These abnormalities were associated with a significant drop in the body temperature by 1.5 °C on average. Ten minutes occlusion in animals from groups A and B resulted in an MEP amplitude decrease by 41.6%, latency increase by 0.9 ms, and temperature decrease by 2.9 °C of the initial value. In animals from groups C and D, five minutes of recovery of arterial blood flow evoked stabilization of the MEP amplitude by 23.4%, latency by 0.5 ms, and temperature by 0.8 °C of the initial value. In histological studies, the results showed that ischemia was most prominent bilaterally in sensory and motor areas, mainly for the forelimb, rather than the hindlimb, innervation of the cortex, putamen and caudate nuclei, globulus pallidus, and areas adjacent to the fornix of the third ventricle. We found that the MEP amplitude parameter is more sensitive than the latency and temperature variability in monitoring the ischemia effects course following common carotid artery infarction, although all parameters are correlated with each other. Temporary five-minute lasting occlusion of common carotid arteries does not evoke total and permanent inhibition in the activity of corticospinal tract neurons in experimental conditions. The symptoms of rat brain infarction are much more optimistic than those described in patients after stroke, and require further comparison with the clinical observations.

Inter-synergized Neuroprotection of Costunolide Engineered Bone Marrow Mesenchymal Stem Cells Targeting System

Treatment of stroke remains difficult due to the unsatisfactory or unlocalized delivery of small molecule- and cell-based therapeutics in injured brain tissues. This is particularly the case for costunolide (Cos), which is highly neuroprotective and anti-inflammatory but finds great difficulty in reaching the brain. Here, we present that Cos induces the differentiation of bone marrow mesenchymal stem cells (bMSCs) into glia-like cells (C-bMSCs) capable of secreting neurotrophic factors and homing to injured brain tissues. By taking advantage of the homing effect, Cos and C-bMSCs were simultaneously funneled into the damaged brain by: (i) preparing Cos micelles (Cos-M) through entrapping Cos into the amphiphilic copolymer mPEG-PLGA [poly(ethylene oxide) monomethyl ether-poly(lactide-co-glycolide)], and (ii) incorporating Cos-M into C-bMSCs to give an intravenously injectable cell-like composite termed Cos@C-bMSCs, which displayed the inter-synergized neuroprotective efficacy in the cerebral ischemia reperfusion (CIR) injured rats. As desired, in the injured brain area, Cos@C-bMSCs simultaneously released Cos and C-bMSCs (glia-like cells) to repair the injured brain and to secret neurotrophic factors such as nerve growth factor (NGF). In view of the availability and reliability of autologous MSCs, the proof-of-concept design, development, and in vivo efficacy of Cos@C-bMSCs signify a movement in our management of brain damages.

Serum and brain metabolomic study reveals the protective effects of Bai-Mi-Decoction on rats with ischemic stroke

Bai-Mi-Decoction (BMD), which is composed of Eugenia caryophyllata, Myristica fragrans, Moschus berezovskii, and Crocus sativu, is a characteristic TCM multi-herb formula for brain disease. However, the mechanism of protective effects of BMD on ischemic stroke (IS) still has not been clarified. Our study is designed to elucidate the protective effects and underlying mechanisms of BMD on IS by employing pharmacodynamic and serum and brain metabolomic methods. In this experiment, 90 adult male Sprague-Dawley rats were randomly divided into the sham operation group (SHAM, vehicle), middle cerebral artery occlusion-reperfusion injury model group (MCAO/R, vehicle), positive control group (NMDP, 36 mg/kg/day nimodipine), and low (BMDL, 0.805 g/kg/day), moderate (BMDM, 1.61 g/kg/day), and high (BMDH, 3.22 g/kg/day) dosage of BMD prophylactic administration groups. The drugs were dissolved in 0.5% CMC-Na and orally administered to rats with equal volumes (100 g/ml body weight) once a day for 14 consecutive days. Neurological deficit score, cerebral infarct volume, change in body weight, and serum NO, SOD, MDA, GSH, and GSSG levels were determined. Pathological abnormalities using hematoxylin and eosin staining and the expression of VEGF, caspase-3, and NF-κB were analyzed. Furthermore, serum and brain metabolic profiles were explored to reveal the underlying mechanism using UHPLC-QTOF-MS/MS technology. BMD exhibited significant neuroprotective effects on MCAO/R rats. As compared to the MCAO/R model group, it could reduce the neurological deficit score and cerebral infarct volume, increase body weight, enhance GSH, SOD, and GSSG activities, and decrease NO and MDA contents of MCAO/R rats. Meanwhile, BMD could ameliorate pathological abnormalities of MCAO/R rats through reducing neuronal loss, vacuolated spaces, shrunken neurons, and destructed neuron structure, as well as regulating the expression of VEGF, caspase-3, and NF-κB. UHPLC-QTOF-MS/MS-based serum and brain metabolomics analysis found a total of 53 differential metabolites between MCAO/R and SHAM groups, of which 30 were significantly regulated by BMD intervention, and further metabolic pathway analysis implied that the protective effects were mainly associated with amino acid and glycerophospholipid metabolisms. Our pharmacodynamic and metabolomic results revealed the neuroprotective effects of BMD on MCAO/R rats, and the underlying mechanisms were probably related to amino acid and glycerophospholipid metabolisms.

The Combination of Individual Herb of Mi-Jian-Chang-Pu Formula Exerts a Synergistic Effect in the Treatment of Ischemic Stroke in Rats

Mi-Jian-Chang-Pu formula (MJCPF), composed of Crocus sativus L. and Acorus tatarinowii Schott, is a well-known TCM for treatment of hemiplegia, facial paralysis as well as language dysfunction caused by stroke both in ancient and modern times. By using pharmacodynamics, pharmacokinetics, and metabolomics, our present study discusses whether the combination of individual herbs or major active components of MJCPF possess synergistic neuroprotective effects against ischemic stroke (IS). 108 adult male Sprague-Dawley rats were randomly and equally divided into 9 groups, including sham group (N, vehicle), middle cerebral artery occlusion (MCAO) model group (M, vehicle), positive group (P, 36 mg/kg/day nimodipine), crocin I (A1, 40 mg/kg/day), β-asarone (B1, 15 mg/kg/day), crocin I + β-asarone (A1B1, 55 mg/kg/day), C. sativus (A, 580 mg/kg/day), A. tatarinowii (B, 480 mg/kg/day), and C. sativus + A. tatarinowii, also named MJCPF (AB, 1060 mg/kg/day) groups. All drugs were orally administered to rats once a day for 14 consecutive days. Neurological deficit score, cerebral infarct volume, body weight change, TTC, HE and IHC staining, behavioral evaluation, metabolic profiles, and pharmacokinetic parameters were determined. MCAO led to severe brain damage including large infarct volume, more severe brain tissue injury, and worse neurological function as compared to the sham rats. All treatment groups showed a significant neuroprotective effect on MCAO rats. Furthermore, the pharmacodynamics' results demonstrated that MJCPF had a synergistic effect evidenced by small infarct volume, more regular arrangement of neuronal cells, and more improved neural function, and the levels of inflammatory factors were closer to normality. A total of 53 differential metabolites between MCAO and sham groups were screened by integration of serum and brain metabolisms, all of which were restored at varying degrees in treatment. PCA and PLS-DA analysis showed that the levels of differential metabolites treated with MJCPF were closer to the sham group than the individual herb and single compound alone or A1B1 combination. The pharmacokinetic parameters further verified the above results that MJCPF could synergistically promote drug absorption greater than others. Our integrated pharmacodynamics, metabolomics, and pharmacokinetic approach reveals the synergistic effect of MJCPF on treatment of IS, which powerfully contribute to the understanding of scientific connotation of TMC formula.

A Review on Preclinical Models of Ischemic Stroke: Insights Into the Pathomechanisms and New Treatment Strategies

BACKGROUND

Stroke is a serious neurovascular problem and the leading cause of disability and death worldwide. The disrupted demand to supply ratio of blood and glucose during cerebral ischemia develops hypoxic shock, and subsequently necrotic neuronal death in the affected regions. Multiple causal factors like age, sex, race, genetics, diet, and lifestyle play an important role in the occurrence as well as progression of post-stroke deleterious events. These biological and environmental factors may be contributed to vasculature variable architecture and abnormal neuronal activity. Since recombinant tissue plasminogen activator is the only clinically effective clot bursting drug, there is a huge unmet medical need for newer therapies for the treatment of stroke. Innumerous therapeutic interventions have shown promise in the experimental models of stroke but failed to translate it into clinical counterparts.

METHODS

Original publications regarding pathophysiology, preclinical experimental models, new targets and therapies targeting ischemic stroke have been reviewed since the 1970s.

RESULTS

We highlighted the critical underlying pathophysiological mechanisms of cerebral stroke and preclinical stroke models. We discuss the strengths and caveats of widely used ischemic stroke models, and commented on the potential translational problems. We also describe the new emerging treatment strategies, including stem cell therapy, neurotrophic factors and gut microbiome-based therapy for the management of post-stroke consequences.

CONCLUSION

There are still many inter-linked pathophysiological alterations with regards to stroke, animal models need not necessarily mimic the same conditions of stroke pathology and newer targets and therapies are the need of the hour in stroke research.

Potential Therapeutic Effects of Mi-Jian-Chang-Pu Decoction on Neurochemical and Metabolic Changes of Cerebral Ischemia-Reperfusion Injury in Rats

As a traditional Chinese medicine formula, Mi-Jian-Chang-Pu decoction (MJCPD) has been successfully used in patients with language dysfunction and hemiplegia after ischemic stroke (IS). Given the excellent protective effects of MJCPD against nerve damage caused by IS in clinical settings, the present investigation mainly focused on its underlying mechanism on ischemia-reperfusion (IR) injury. Firstly, by applying the MCAO-induced cerebral IR injury rats, the efficacy of MJCPD on IS was estimated using the neurological deficit score, TTC, HE, and IHC staining, and neurochemical measurements. Secondly, an UHPLC-QTOF-MS/MS-based nontargeted metabolomics was developed to elucidate the characteristic metabolites. MJCPD groups showed significant improvements in the neurological score, infarction volume, and histomorphology, and the changes of GSH, GSSG, GSH-PX, GSSG/GSH, LDH, L-LA, IL-6, TNF-α, and VEGF-c were also reversed to normal levels after the intervention compared to the MCAO model group. Metabolomics profiling identified 21 different metabolites in the model group vs. the sham group, 10 of which were significantly recovered after treatment of MJCPD, and those 10 metabolites were all related to the oxidative stress process including glucose, fatty acid, amino acid, glutamine, and phospholipid metabolisms. Therefore, MJCPD might protect against IS by inhibiting oxidative stress during IR.

Zinc finger E-Box binding homeobox 2 (ZEB2)-induced astrogliosis protected neuron from pyroptosis in cerebral ischemia and reperfusion injury

Ischemia injury can cause cell death or impairment of neuron and astrocytes, and thus induce loss of nerve function. central nervous systems injury induces an aberrant activation of astrocytes called astrogliosis. Pyroptosis, which is a kind of programmed cell death, was proved play an important role in ischemia injury. Zinc Finger E-Box Binding Homeobox 2 (ZEB2) promoted neuron astrogliosis, which play a protected role in neuron regeneration. However, its precise mechanism remains unclear. This study investigated the mechanism of ZEB2 on astrogliosis and neuron regeneration after cerebral ischemia reperfusion condition. To confirm our hypothesis, Neurons and astrocytes were isolated from fetal Sprague Dawley rats, in vivo Middle Cerebral Artery Occlusion/reperfusion (MCAO/R) rat model and in vitro oxygen-glucose deprivation/reperfusion (OGD/R)-treated astrocytes and neurocytes model were constructed. Our results showed that ZEB2 was expressed in nucleus of astrocyte and upregulated after OGD/R induction, ZEB2 promoted astrogliosis. Further upregulation of ZEB2 promoted the astrogliosis, which promoted neuron proliferation and regeneration by decreased pyroptosis. Moreover, this finding was further confirmed in vivo MCAO/R rat model. Overexpression of ZEB2 promoted astrogliosis, which decreased infarct volume and accumulated recovery of neurological function by alleviated pyroptosis. This finding revealed that ZEB2 was a regulator of the astrogliosis after ischemia/reperfusion injury, and then astrogliosis promoted neuron regeneration via decreased neuron pyroptosis. Therefore, ZEB2 may be a potential therapeutic target for ischemia/reperfusion injury.

Animal models of stroke

Stroke is a devastating disease with high morbidity and mortality. Animal models are indispensable tools that can mimic stroke processes and can be used for investigating mechanisms and developing novel therapeutic regimens. As a heterogeneous disease with complex pathophysiology, mimicking all aspects of human stroke in one animal model is impossible. Each model has unique strengths and weaknesses. Models such as transient or permanent intraluminal thread occlusion middle cerebral artery occlusion (MCAo) models and thromboembolic models are the most commonly used in simulating human ischemic stroke. The endovascular filament occlusion model is characterized by easy manipulation and accurately controllable reperfusion and is suitable for studying the pathogenesis of focal ischemic stroke and reperfusion injury. Although the reproducibility of the embolic model is poor, it is more convenient for investigating thrombolysis. Rats are the most frequently used animal model for stroke. This review mainly outlines the stroke models of rats and discusses their strengths and shortcomings in detail.

Zeb2/Axin2-Enriched BMSC-Derived Exosomes Promote Post-Stroke Functional Recovery by Enhancing Neurogenesis and Neural Plasticity

Exosomes harvested from bone marrow-derived mesenchymal stromal cells (BMSCs) have shown treatment potential in many diseases. In vitro, Zeb2/Axin2 stimulated endogenous neurogenesis, which induced functional recovery after stroke. Here, we investigated whether the Zeb2/Axin2-enriched exosomes harvested from BMSCs transfected with a Zeb2/Axin2 overexpression plasmid would enhance neurological recovery. Compared with the control, both exosome treatments significantly improved functional recovery, and Zeb2/Axin2-enriched exosomes had significantly more improved effects on neurological function, neurogenesis, and neurite remodeling/neuronal dendrite plasticity than the control BMSC exosome treatment in a middle cerebral artery occlusion MCAO rat model. After stimulation with Zeb2/Axin2-enriched BMSC exosomes, the spatial memory and nerve function of MCAO rats showed marked recovery. The number of neurons was increased in the subventricular zone (SVZ), hippocampus, and cortex area, while the expression of nerve growth factors (NGF, BDNF, etc.) was upregulated. In the ischemic boundary zone, Zeb2/Axin2-enriched exosomes promoted synaptic remodeling by increasing the number of synapses and reversed the axonal loss of phosphorylated neurofilament (SMI-31) and synaptophysin (SYN) caused by ischemic injury, thus alleviating axonal demise and promoting synaptic proliferation. In vitro, Zeb2/Axin2-enriched exosomes significantly increased neurite branching and elongation of cultured cortical embryonic rat neurons under oxygen- and glucose-deprived (OGD) conditions. Moreover, Ex-Zeb2/Axin2-enriched exosomes downregulated the protein level of SOX10, endothelin-3/EDNRB, and Wnt/β-catenin expression. In conclusion, exosomes harvested from Ex-Zeb2/Axin2 BMSC could improve post-stroke neuroplasticity and functional recovery in MCAO rats by promoting proliferation and differentiation of neural stem cells. The mechanism may be related to the SOX10, Wnt/β-catenin, and endothelin-3/EDNRB pathways.

Association of central arterial stiffness with hippocampal blood flow and N-acetyl aspartate concentration in hypertensive adult Dahl salt sensitive rats

BACKGROUND

Central arterial stiffness (CAS) is associated with elevated arterial blood pressure (BP) and is likely associated with stiffening of cerebral artery walls, with attendant cerebral hypoperfusion, neuronal density loss and cognitive decline. Dahl salt-sensitive (Dahl-S) rats exhibit age-associated hypertension and memory loss, even on a normal salt intake.

METHOD

We sought to explore whether central arterial pulse wave velocity (PWV), a marker of CAS, is associated with hippocampal cerebral blood flow (CBF) and neuronal density in hypertensive Dahl-S rats. We measured systolic BP (by tail-cuff plethysmography), aortic PWV (by echocardiography) and CBF and N-acetyl aspartate (NAA) (by magnetic resonance imaging) in 6 month-old male Dahl-S rats (n = 12).

RESULTS

Greater PWV was significantly associated with lower CBF and lower NAA concentration in the hippocampus, supporting a role of CAS in cerebrovascular dysfunction and decline in cognitive performance with aging.

CONCLUSION

These findings implicate increased CAS in cerebral hypoperfusion and loss of neuronal density and function in the Dahl-S model of age-associated cardiovascular dysfunction.

Release rate is a key variable affecting the therapeutic effectiveness of liposomal fasudil for the treatment of cerebral ischemia/reperfusion injury

Liposomal fasudil as a treatment for cerebral ischemia/reperfusion (I/R) injury has been demonstrated to be effective in animal models due to the high accumulation of liposomes in damaged brain tissue. However, it is still unclear what effect drug release rate has on the treatment of I/R injury, where pathology progresses dramatically in a short time. In the present study, we assessed four formulations of liposomal fasudil. The results of an in vitro drug release assay showed that the release properties of fasudil were changed by varying the lipid composition and internal phase of the liposomes. Based on these results, differences in the transition of fasudil plasma concentration were monitored after the administration of each type of liposomal fasudil in normal rats. A pharmacokinetic study showed that higher levels of drug retention in liposomal fasudil resulted in higher fasudil plasma concentration. Finally, treatment of I/R injury model rats with liposomal fasudil revealed that a mid-level release rate of fasudil from liposomes resulted in the greatest therapeutic effect among the formulations. In conclusion, these results demonstrate that an optimized drug release rate from liposomes enhances the therapeutic effect of fasudil for the treatment of cerebral I/R injury.

Human neural stem cells improve early stage stroke outcome in delayed tissue plasminogen activator-treated aged stroke brains

INTRODUCTION

Clinically, significant stroke injury results from ischemia-reperfusion (IR), which induces a deleterious biphasic opening of the blood-brain barrier (BBB). Tissue plasminogen activator (tPA) remains the sole pharmacological agent to treat ischemic stroke. However, major limitations of tPA treatment include a narrow effective therapeutic window of 4.5 h in most patients after initial stroke onset and off-target non-thrombolytic effects (e.g., the risk of increased IR injury). We hypothesized that ameliorating BBB damage with exogenous human neural stem cells (hNSCs) would improve stroke outcome to a greater extent than treatment with delayed tPA alone in aged stroke mice.

METHODS

We employed middle cerebral artery occlusion to produce focal ischemia with subsequent reperfusion (MCAO/R) in aged mice and administered tPA at a delayed time point (6 h post-stroke) via tail vein. We transplanted hNSCs intracranially in the subacute phase of stroke (24 h post-stroke). We assessed the outcomes of hNSC transplantation on pathophysiological markers of stroke 48 h post-stroke (24 h post-transplant).

RESULTS

Delayed tPA treatment resulted in more extensive BBB damage and inflammation relative to MCAO controls. Notably, transplantation of hNSCs ameliorated delayed tPA-induced escalated stroke damage; decreased expression of proinflammatory factors (tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6), decreased the level of matrix metalloprotease-9 (MMP-9), increased the level of brain-derived neurotrophic factor (BDNF), and reduced BBB damage.

CONCLUSIONS

Aged stroke mice that received delayed tPA treatment in combination with hNSC transplantation exhibited reduced stroke pathophysiology in comparison to non-transplanted stroke mice with delayed tPA. This suggests that hNSC transplantation may synergize with already existing stroke therapies to benefit a larger stroke patient population.

The protective effect of cordyceps sinensis extract on cerebral ischemic injury via modulating the mitochondrial respiratory chain and inhibiting the mitochondrial apoptotic pathway

Cerebral ischemia is a common refractory brain disease, resulting from a reduction in the blood flow to the brain. Mitochondrial dysfunction leads to ischemic stroke and brain injury. Cordyceps sinensis (CS) is an important traditional Chinese medicine, which has been linked to neuroprotection in recent studies. In this study, we investigated the role of the mitochondrial respiratory chain and the mitochondrial apoptotic pathway on the protective effect of Cordyceps sinensis extract (CSE) against cerebral ischemia injury both in vivo and in vitro. In a murine middle cerebral artery occlusion (MCAO) model, administration of CSE relieved neuronal morphological damage and attenuated the neuronal apoptosis. CSE also reduced neurobehavioral scores and oxygen free radical (OFR), while improving the levels of ATP, cytochrome c oxidase (COX), and mitochondrial complexes I-IV. Furthermore, the mRNA expression of Bax, cytochrome c (Cyt c) and caspase-3 were down-regulated. In brain microvascular endothelial cells (BMECs) exposed to oxygen and glucose deprivation (OGD), CSE prevented OGD-induced cellular apoptosis, and recovered the reduction of mitochondrial membrane potential (MMP). Moreover, CSE treatment induced an increase of Bcl-2 protein expression and a decrease of Bax, Cyt c and caspase-3 protein expression. Meanwhile, the caspase-3, -8, and -9 activities were also inhibited. The results indicate that CSE can relieve cerebral ischemia injury and exhibit protective effects via modulating the mitochondrial respiratory chain and inhibiting the mitochondrial apoptotic pathway.

Models of poststroke depression and assessments of core depressive symptoms in rodents: How to choose?

Our previous studies have indicated that depression and declined cognition have been involved in some neurodegenerative diseases including Stroke, Parkinson's diseases and Vascular Parkinsonism. Post-stroke depression (PSD) is the most common psychiatric disorder following a stroke and has high morbidity and mortality. Studies on PSD are increasingly common, but the specific mechanisms remain unknown. Current research mainly includes clinical and animal aspects. Questionnaires and peripheral blood examination are two of the most common methods used to study clinical PSD. The results of questionnaires are influenced by multiple factors such as disease history, education background, occupation, economic status, family relationships and social support. There are certain limitations to blood sample testing; for example, it is influenced by cerebrovascular diseases and some other disruptions of the internal environment. It is difficult for either method to fully clarify the pathophysiological mechanism of PSD. Animal models provide alternative methods to further understand the pathophysiological mechanisms of PSD, such as the involvement of neuronal circuits and cytokines. More than ten animal models of PSD have been developed, and new models are constantly being introduced. Therefore, it is important to choose the appropriate model for any given study. In this paper, we will discuss the characteristics of the different models of PSD and comment on the advantages and disadvantages of each model, drawing from research on model innovation. Finally, we briefly describe the current assessment methods for the core symptoms of PSD models, point out the shortcomings, and present the improved sucrose preference test as a rational evaluation of anhedonia.

Pathological Comparisons of the Hippocampal Changes in the Transient and Permanent Middle Cerebral Artery Occlusion Rat Models

Ischemic strokes are categorized by permanent or transient obstruction of blood flow, which impedes delivery of oxygen and essential nutrients to brain. In the last decade, the therapeutic window for tPA has increased from 3 to 5-6 h, and a new technique, involving the mechanical removal of the clot (endovascular thrombectomy) to allow reperfusion of the injured area, is being used more often. This last therapeutic approach can be done until 24 h after stroke onset. Due to this fact, more acute ischemic stroke patients are now being recanalized, and so tMCAO is probably the "best" model to address these patients that have a potential good outcome in terms of survival and functional recovery. However, permanent occlusion patients are also important, not only to increase survival rate but also to improve functional outcomes, although these are more difficult to achieve. So, both models are important, and which target different stroke patients in the clinical scenario. Hippocampus has a vital role in memory and cognition, is prone to ischemic induced neurodegeneration. This study was designed to delineate the molecular, pathological, and neurological changes in rat models of t-MCAO, permanent MCAO (pMCAO), and pMCAO with diabetic conditions in hippocampal tissue. Our results showed that these three models showed distinct discrepancies at numerous pathological process, including key signaling molecules involved in neuronal apoptosis, glutamate induced excitotoxicity, neuroinflammation, oxidative stress, and neurotrophic changes. Our result suggests that the two commonly used MCAO models exhibited tremendous differences in terms of neuronal cell loss, glutamate excitotoxic related signaling, synaptic transmission markers, neuron inflammatory and oxidative stress molecules. These differences may reflect the variations in different models, which may provide valuable information for mechanistic and therapeutic inconsistences as experienced in both preclinical models and clinical trials.

Suppression of Cerebral Ischemia/Reperfusion Injury by Efficient Release of Encapsulated Ifenprodil From Liposomes Under Weakly Acidic pH Conditions

Although N-methyl-d-aspartate receptor antagonists are hopeful therapeutic agents against cerebral ischemia/reperfusion (I/R) injury, effective approaches are needed to allow such agents to pass through the blood-brain barrier, thus increasing bioavailability of the antagonists to realize secure treatment. We previously demonstrated the usefulness of liposomal delivery of neuroprotectants via spaces between the disrupted blood-brain barrier induced after cerebral I/R. In the present study, a liposomal formulation of an N-methyl-d-aspartate receptor antagonist, ifenprodil, was newly designed; and the potential of liposomal ifenprodil was evaluated in transient middle cerebral artery occlusion rats. Ifenprodil was encapsulated into liposomes by a remote loading method using pH gradient between internal and external water phases of liposomes, focusing on differences of its solubility in water depending on pH. The encapsulated ifenprodil could be quickly released from the liposomes in vitro under a weakly acidic pH condition, which is a distinctive condition after cerebral I/R. Liposomal ifenprodil treatment significantly alleviated I/R-induced increase in permeability of the BBB by inhibiting superoxide anion production, resulting in ameliorating ischemic brain damage. Taken together, these results suggest that Ifen-Lip could become a hopeful neuroprotectant for cerebral I/R injury via efficient release of the encapsulated ifenprodil under weakly acidic pH conditions.

Applications of Liposomal Drug Delivery Systems to Develop Neuroprotective Agents for the Treatment of Ischemic Stroke

Ischemic stroke is one of the leading causes of severe disability and death. In clinical settings, tissue plasminogen activator (t-PA) for thrombolytic therapy is the only globally approved drug for the treatment of ischemic stroke. However, the proportion of patients who receive t-PA therapy is extremely limited due to its narrow therapeutic time window (TTW) and the risk of cerebral hemorrhage. Cerebral ischemia-reperfusion (I/R) injury is also a serious problem for patients' outcomes. Hence, the development of more effective therapies has been desired to prolong the TTW of t-PA and prevent cerebral I/R injury. For delivering drugs into the brain, the blood-brain barrier (BBB) must be overcome since it limits drug penetration into the brain, leading to insufficient therapeutic efficacy. As a distinctive pathology after an ischemic stroke, it was reported that the vascular permeability of the BBB is increased around the ischemic region. We found that nano-sized liposomes can pass through the disrupted BBB and accumulate in the I/R region, and that delivery of neuroprotective agents using a liposomal drug delivery system (DDS) is effective for the treatment of cerebral I/R injury. Moreover, we have recently demonstrated that combination therapy with liposomal drugs and t-PA can suppress the deleterious effects of t-PA and extend its TTW in a rat ischemic stroke model. These findings indicate that applications of nanoparticle DDS technology could be a hopeful approach to drug development for ischemic stroke therapy. In this review, we introduce our findings on ischemic stroke treatment using liposomal DDS and recent advances from other research groups.

Neuregulin-1β Plays a Neuroprotective Role by Inhibiting the Cdk5 Signaling Pathway after Cerebral Ischemia-Reperfusion Injury in Rats

This study investigated the effects of neuregulin-1β (NRG1β) after middle cerebral artery occlusion/reperfusion (MCAO/R) in rats to evaluate whether they occur via the cyclin-dependent kinase (Cdk)5 signaling pathway. One hundred adult male Wistar rats were randomly divided into sham, MCAO/R, treatment (NRG1β), inhibitor (roscovitine; Ros), and inhibitor + treatment (Ros + NRG1β) groups. The MCAO/R model was established using the intraluminal thread method. The neurobehavioral function was evaluated by the modified neurological severity score (mNSS). The cerebral infarction volume (CIV) was measured by triphenyl tetrazolium chloride (TTC) staining. Morphological changes were observed by hematoxylin-eosin (HE) staining. The apoptotic cell index (ACI) was detected by the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Immunohistochemistry and Western blotting were performed to detect the expression of calpain 1, p35/p25 (regulatory binding partners of Cdk5), Cdk5, and p-Tau in neurons. The neuronal morphology in the MCAO/R, NRG1β, Ros + NRG1β, and Ros groups differed compared to the sham group; the mNSS, CIV, ACI, and the expression of calpain 1, p35/p25, Cdk5, and p-Tau were significantly increased in all four groups (P < 0.05). In the NRG1β, Ros and Ros + NRG1β groups, the neuronal morphology was significantly improved compared to the MCAO/R group, as were the mNSS, CIV, and ACI. The levels of calpain 1, p35/p25, and p-Tau were decreased compared with the MCAO/R group (P < 0.05), while the Cdk5 expression was not significantly different (P > 0.05). NRG1β may exert neuroprotective effects by inhibiting the expression of calpain 1, p35/p25, and p-Tau after cerebral ischemia-reperfusion injury.

Low-frequency ESR studies on permeable and impermeable deuterated nitroxyl radicals in corn oil solution

Low-frequency electron spin resonance studies were performed for 2 mM concentration of deuterated permeable and impermeable nitroxyl spin probes, 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl and 3-carboxy-2,2,5,5,-tetramethyl-1-pyrrolidinyloxy in pure water and various concentrations of corn oil solution. The electron spin resonance parameters such as the line width, hyperfine coupling constant, g factor, rotational correlation time, permeability, and partition parameter were estimated. The broadening of line width was observed for nitroxyl radicals in corn oil mixture. The rotational correlation time increases with increasing concentration of corn oil, which indicates the less mobile nature of spin probe in corn oil mixture. The membrane permeability and partition parameter values were estimated as a function of corn oil concentration, which reveals that the nitroxyl radicals permeate equally into the aqueous phase and oil phase at the corn oil concentration of 50%. The electron spin resonance spectra demonstrate the permeable and impermeable nature of nitroxyl spin probes. From these results, the corn oil concentration was optimized as 50% for phantom studies. In this work, the corn oil and pure water mixture phantom models with various viscosities correspond to plasma membrane, and whole blood membrane with different hematocrit levels was studied for monitoring the biological characteristics and their interactions with permeable nitroxyl spin probe. These results will be useful for the development of electron spin resonance and Overhauser-enhanced magnetic resonance imaging modalities in biomedical applications.

Intervention effect of total flavonoids of ilex pubesceus on tolerant rat models under cerebral anoxia

Objective: To observe the intervention effect of total flavonoid of ilex pubesceus on animal models of cerebral ischemic tolerance. Methods: A rat model of global-focal cerebral ischemic tolerance was established by blocking bilateral common carotid artery blood flow and occluding left middle cerebral artery using thread-occlusion method. After the first operation, the Ginaton group and large-dosage, medium-dosage and small-dosage groups of total flavonoid of ilex pubesceus were given intragastric administration of corresponding drugs. The sham-operated group, pretreatment model group and ischemia-reperfusion group were given intragastric administration of the same volume of normal saline, 1 time a day, and administrated for 4d. At 24 h after the second operation, the neurological deficit was assessed, the whole blood viscosity, plasma viscosity, iNOS activity as well as NO level, IL-1β content and TNF-α content in the brain tissue of the rats were determined, and the morphological changes of brain tissue of the rats were observed by HE staining. Results: All the rat models of cerebral ischemic tolerance were established successfully. The total flavonoid of ilex pubesceus can obviously or significantly reduce the neurological deficit score, whole blood viscosity and plasma viscosity, obviously or significantly increase the NO level in the brain tissue of the rats, and significantly reduce the pathological damage of brain tissue of the rats. But compared with the ischemia-reperfusion group, the total flavonoid of ilex pubesceus can significantly or obviously increase the iNOS activity, IL-1β content and TNF-α content in the brain tissue of the rats.

Neuroprotective effect of total flavonoids from Ilex pubescens against focal cerebral ischemia/reperfusion injury in rats

Ilex pubescens is commonly used in traditional Chinese medicine to treat cardiovascular and cerebrovascular diseases, such as coronary artery disease and stroke. However, the underlying mechanisms remain to be fully elucidated. The aim of the present study was to investigate the effects of Ilex pubescens total flavonoids (IPTF) on neuroprotection and the potential mechanisms in a rat model of focal cerebral ischemia/reperfusion (I/R) injury. Rats were pretreated with intragastric administration of IPTF at doses of 200 and 100 mg/kg for 5 days; middle cerebral artery occlusion surgery was then performed to induce cerebral I/R injury. Neurological deficits were determined using the 5‑point neurological function score evaluation system, brain infarct sizes were determined by 2,3,5‑triphenyltetrazolium chloride staining and alterations in brain histology were determined by hematoxylin and eosin staining. The neurological deficit score, the infarcted area and the brain tissue pathological injury were significantly reduced when the rats were pretreated with IPTF. In addition, inflammatory mediators and neurotrophic factors in the brain were investigated. IPTF pretreatment decreased the activities of total nitric oxide synthase (TNOS), induced NOS (iNOS) and constitutive NOS (cNOS), and the levels of nitric oxide (NO), interleukin‑1β (IL‑1β) and tumor necrosis factor‑α (TNF‑α), however, it increased the levels of IL‑10 in brain tissues. Furthermore, pretreatment with IPTF also increased the protein expressions of brain‑derived neurotrophic factor, glial cell‑derived neurotrophic factor and vascular endothelial growth factor, when compared with the model group. In conclusion, the results of the present study demonstrated that IPTF has a neuroprotective effect against focal cerebral I/R injury in rats. The mechanism may be associated with the decreased production of certain proinflammatory cytokines including NO, IL‑1β, TNF‑α, TNOS, iNOS and cNOS, the increased production of the anti‑inflammatory cytokine IL‑10 and the increased secretion of neurotrophic factors.

Stem cell transplantation therapy for multifaceted therapeutic benefits after stroke

One of the exciting advances in modern medicine and life science is cell-based neurovascular regeneration of damaged brain tissues and repair of neuronal structures. The progress in stem cell biology and creation of adult induced pluripotent stem (iPS) cells has significantly improved basic and pre-clinical research in disease mechanisms and generated enthusiasm for potential applications in the treatment of central nervous system (CNS) diseases including stroke. Endogenous neural stem cells and cultured stem cells are capable of self-renewal and give rise to virtually all types of cells essential for the makeup of neuronal structures. Meanwhile, stem cells and neural progenitor cells are well-known for their potential for trophic support after transplantation into the ischemic brain. Thus, stem cell-based therapies provide an attractive future for protecting and repairing damaged brain tissues after injury and in various disease states. Moreover, basic research on naïve and differentiated stem cells including iPS cells has markedly improved our understanding of cellular and molecular mechanisms of neurological disorders, and provides a platform for the discovery of novel drug targets. The latest advances indicate that combinatorial approaches using cell based therapy with additional treatments such as protective reagents, preconditioning strategies and rehabilitation therapy can significantly improve therapeutic benefits. In this review, we will discuss the characteristics of cell therapy in different ischemic models and the application of stem cells and progenitor cells as regenerative medicine for the treatment of stroke.

Intraluminal spindle-shaped-head suture induced occlusion of middle cerebral artery in the rats

OBJECTIVE

This study aimed to introduce a modified animal model of middle cerebral arterial occlusion (MCAO) through placement of intraluminal spindle-shaped head suture by comparing the traditional MCAO model.

METHODS

A total of 60 male Spraque-Dawley (SD) rats were divided into two groups and MCAO was induced using spindle-shaped head suture or round head suture. The mortality, infarct volume, neurological function, success rate of the surgery, and stability of modeling were examined to evaluate the effectiveness of this model.

RESULTS

Our results showed the success rate was 90.0% in spindle-shaped head group and 83.3% in round head group showing no significant difference; spindle-shaped head achieved a better establishment of MCAO model as shown in neurological examination. The infarct volume was 31.99 ± 5.44% in spindle-shaped head group and was significantly higher than in round head group (24.59 ± 7.17%; p < 0.05), and the coefficient of variation of infarct volume in spindle-shaped head group was lower than in round head group.

CONCLUSION

Our findings indicate that the modified suture induces a more reproducible and stable ischemic stroke following MCAO in SD rats.

RETRACTED: Role of fractalkine/CX3CR1 signaling pathway in the recovery of neurological function after early ischemic stroke in a rat model

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the authors and Editor-in-Chief. Concern was raised about the reliability of the Western blot results, as detailed here: https://pubpeer.com/publications/7BB8F6559AF31100A59484E5D97802; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. In addition, a portion of Figure 5A, CA3 ‘Positive control’ group appears to contain image similarities with Figure 5A, CA1 ‘CX3CR1 inhibitor’ group. The journal requested that the corresponding author comment on these concerns and provide the raw data. However, the authors were not able to satisfactorily fulfill this request and therefore the Editor-in-Chief decided to retract the article.

RhGLP-1 (7-36) protects diabetic rats against cerebral ischemia-reperfusion injury via up-regulating expression of Nrf2/HO-1 and increasing the activities of SOD

The present study aimed to explore the neuroprotective effect and possible mechanisms of rhGLP-1 (7–36) against transient ischemia/reperfusion injuries induced by middle cerebral artery occlusion (MCAO) in type 2 diabetic rats. First, diabetic rats were established by a combination of a high-fat diet and low-dose streptozotocin (STZ) (30 mg/kg, intraperitoneally). Second, they were subjected to MCAO for 2 h, then treated with rhGLP-1 (7–36) (10, 20, 40 µg/kg i.p.) at the same time of reperfusion. In the following 3 days, they were injected with rhGLP-1 (7–36) at the same dose and route for three times each day. After 72 h, hypoglycemic effects were assessed by blood glucose changes, and neuroprotective effects were evaluated by neurological deficits, infarct volume and histomorphology. Mechanisms were investigated by detecting the distribution and expression of the nuclear factor erythroid-derived factor 2 related factor 2 (Nrf2) in ischemic brain tissue, the levels of phospho-PI3 kinase (PI3K)/PI3K ratio and heme-oxygenase-1 (HO-l), as well as the activities of superoxide dismutase (SOD) and the contents of malondialdehyde (MDA). Our results showed that rhGLP-1 (7–36) significantly reduced blood glucose and infarction volume, alleviated neurological deficits, enhanced the density of surviving neurons and vascular proliferation. The nuclear positive cells ratio and expression of Nrf2, the levels of P-PI3K/PI3K ratio and HO-l increased, the activities of SOD increased and the contents of MDA decreased. The current results indicated the protective effect of rhGLP-1 (7–36) in diabetic rats following MCAO/R that may be concerned with reducing blood glucose, up-regulating expression of Nrf2/HO-1 and increasing the activities of SOD.

Picroside II protects the blood-brain barrier by inhibiting the oxidative signaling pathway in cerebral ischemia-reperfusion injury

BACKGROUND AND PURPOSE

Thrombolysis is used to improve cerebral circulation; at the same time, neuroprotective drugs such as antioxidants should also be used. The aim of these experiments was to explore the protective mechanism of an antioxidant, picroside II, on the blood-brain barrier (BBB) after cerebral ischemia-reperfusion (CI/R) injury.

METHODS

To observe the antagonistic effect of picroside II on CI/R damage, the neurological deficit score and the infarct volume were measured. To detect the protective effect of picroside II on nerve cells and the BBB, the morphology and structure of cortical brain tissue were observed, respectively. To investigate the antioxidant effect and mechanism of picroside II, reactive oxygen species (ROS) content, the activity of Nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase), and the protein levels of Nox2 and Rac-1 were detected. To investigate the protective mechanism of picroside II on the BBB, the levels of ROCK, MLCK, MMP-2 and claudin-5 were tested.

RESULTS

A higher neurological score, bigger cortex infarction, more damaged neuron structure and injured BBB, increased content of ROS and activity of NADPH oxidase, higher protein levels of Nox2, Rac-1, ROCK, MLCK and MMP-2 and lower levels of claudin-5 were observed in the model group. In the picroside group, the neurological score, neuronal damage, BBB injury, ROS content and NADPH oxidase activity were reduced (P<0.05), and the protein levels of Rac-1, Nox2, ROCK, MLCK and MMP-2 were down-regulated (P<0.05), while the expression of claudin-5 was up-regulated (P<0.05).

CONCLUSIONS

Picroside II could protect the nervous system possibly through reducing the content of ROS by down-regulating the expression of Rac-1 and Nox2 and could protect the BBB through reducing the expression of ROCK, MLCK, and MMP-2, while enhancing the expression of claudin-5.

Visual Field Progression is Associated with Systemic Concentration of Macrophage Chemoattractant Protein-1 in Normal-Tension Glaucoma

PURPOSE

To investigate the associations between endothelin-1 (ET-1) and macrophage chemoattractant protein-1 (MCP-1) levels and visual field (VF) progression in normal-tension glaucoma (NTG).

METHODS

We conducted a prospective, longitudinal study in 71 patients with NTG. Blood samples from all subjects were assayed for ET-1 and MCP-1 concentrations, and baseline ophthalmic examinations, including the VF, were performed. Baseline data were compared with follow-up data over 3 years.

RESULTS

After 3 years of follow-up, 14 of the 71 patients showed VF progression, and the systemic MCP-1 level was significantly associated with VF progression (r = 0.318, p = 0.007). Multiple regression analysis showed that VF progression was significantly associated with MCP-1 (odds ratio, OR = 1.021, 95% CI = 1.003-1.040; p = 0.020) and optic disc hemorrhage (ODH; OR = 1.573; 95% CI = 1.140-2.170; p = 0.023).

CONCLUSIONS

Systemic MCP-1 levels were associated with VF progression in patients with NTG.

Ischemic brain injury: New insights on the protective role of melatonin

Stroke represents one of the most common causes of brain's vulnerability for many millions of people worldwide. The plethora of physiopathological events associated with brain ischemia are regulate through multiple signaling pathways leading to the activation of oxidative stress process, Ca²⁺ dyshomeostasis, mitochondrial dysfunction, proinflammatory mediators, excitotoxicity and/or programmed neuronal cell death. Understanding this cascade of molecular events is mandatory in order to develop new therapeutic strategies for stroke. In this review article, we have highlighted the pleiotropic effects of melatonin to counteract the multiple processes of the ischemic cascade. Additionally, experimental evidence supports its actions to ameliorate ischemic long-term behavioural and neuronal deficits, preserving the functional integrity of the blood-brain barrier, inducing neurogenesis and cell proliferation through receptor-dependent mechanism, as well as improving synaptic transmission. Consequently, the synthesis of melatonin derivatives designed as new multitarget-directed products has focused a great interest in this area. This latter has been reinforced by the low cost of melatonin and its reduced toxicity. Furthermore, its spectrum of usages seems to be wide and with the potential for improving human health. Nevertheless, the molecular and cellular mechanisms underlying melatonin´s actions need to be further exploration and accordingly, new clinical studies should be conducted in human patients with ischemic brain pathologies.

Combination therapy with liposomal neuroprotectants and tissue plasminogen activator for treatment of ischemic stroke

For ischemic stroke treatment, extension of the therapeutic time window (TTW) of thrombolytic therapy with tissue plasminogen activator (tPA) and amelioration of secondary ischemia/reperfusion (I/R) injury are most desirable. Our previous studies have indicated that liposomal delivery of neuroprotectants into an ischemic region is effective for stroke treatment. In the present study, for solving the above problems in the clinical setting, the usefulness of combination therapy with tPA and liposomal fasudil (fasudil-Lip) was investigated in ischemic stroke model rats with photochemically induced thrombosis, with clots that were dissolved by tPA. Treatment with tPA 3 h after occlusion markedly increased blood-brain barrier permeability and activated matrix metalloproteinase (MMP)-2 and -9, which are involved in cerebral hemorrhage. However, an intravenous administration of fasudil-Lip before tPA markedly suppressed the increase in permeability and the MMP activation stemming from tPA. The combination treatment showed significantly larger neuroprotective effects, even in the case of delayed tPA administration compared with each treatment alone or the tPA/fasudil-treated group. These findings suggest that treatment with fasudil-Lip before tPA could decrease the risk of tPA-derived cerebral hemorrhage and extend the TTW of tPA and that the combination therapy could be a useful therapeutic option for ischemic stroke.-Fukuta, T., Asai, T., Yanagida, Y., Namba, M., Koide, H., Shimizu, K., Oku, N. Combination therapy with liposomal neuroprotectants and tissue plasminogen activator for treatment of ischemic stroke.

TDB protects vascular endothelial cells against oxygen-glucose deprivation/reperfusion-induced injury by targeting miR-34a to increase Bcl-2 expression

Prolonged ischemia can result in apoptotic death of vascular endothelial cells and lead to ischemic vascular diseases including vascular dementia, arteriosclerosis and brain oedema. Finding protective strategies to prevent this is therefore an urgent mission. Recent studies have shown that dysregulation of microRNAs (miRNAs) can lead to imbalance of Bcl-2 family proteins and mitochondrial dysfunction, leading to further damage of vascular cells under ischemic conditions. However, whether miRNAs can be used as a drug target for treating vascular diseases is not fully understood. In this study, we observed that the natural product 2,4,5-trihydroxybenzaldehyde (TDB) could effectively inhibit vascular cell apoptosis following oxygen-glucose deprivation/reperfusion (OGD/R) by maintaining mitochondrial membrane potential (MMP) and suppressing activation of the mitochondria-dependent caspase-9/3 apoptosis pathway. Furthermore, we identified miR-34a, a crucial negative regulator of Bcl-2, as a target for the protective effect of TDB on vascular cells. TDB-induced suppression of miR-34a resulted in a significant upregulation of Bcl-2 protein, MMP maintenance, and the survival of vascular cells following OGD/R. Our findings suggest that targeting miR-34a with the natural product TDB may provide a novel strategy for the treatment of ischemic vascular injuries, and demonstrate the therapeutic potential in targeting miRNAs using appropriate small molecules.

Pathological and Clinical Analysis of Vascular Catheterization Models in Rats, with Exploration of Interventions to Improve Clinical Tolerance

Permanent vascular catheterization for intravascular access is one of the most commonly applied techniques used on rodents in pharmacology studies. However, use of the intravascular catheters is complicated by nontolerance due to thromboembolic disease and sepsis. We have undertaken an extensive pathologic and clinical analysis of an intravascular catheterization model in Wistar Han and Sprague-Dawley rats, with a particular focus on carotid artery catheterization with or without jugular vein catheterization, in order to define the pathologic mechanisms behind nontolerance and define clinical end points to ensure maximal animal welfare. Further, we have explored various potential solutions to increase the tolerance of the procedure. In these studies, indwelling catheters were found to cause a high degree of thromboembolic disease with infarction in the brain, cecal tip, and kidneys being the primary causes of nontolerance. Loss of greater than 10% body weight was determined to be the most sensitive indicator of nontolerance and was closely correlated with degree of renal parenchymal loss. Sepsis was noted as a very rare complication, indicating that routine aseptic surgical techniques are adequate for preventing this complication.

Is shorter transient middle cerebral artery occlusion (t-MCAO) duration better in stroke experiments on diabetic female Sprague Dawely rats?

AIM

To determine optimal duration of transient middle cerebral artery occlusion (t-MCAO) for a stroke model in female diabetic Sprague-Dawley (SD) rats.

METHODS

Streptozotocin-induced type-1 diabetic SD female rats (n = 25, 12 weeks old, five groups; n = 5 per group) were subjected to different duration of t-MCAO (20, 30, 45, 60 and 90 minutes) followed by reperfusion. A control group of rats without diabetes (n = 5) was subjected to 30 minutes of t-MCAO followed by reperfusion. Twenty-four hours after reperfusion, infarct volumes were evaluated by 2,3,5-triphenyltetrazolium chloride (TTC) staining.

RESULTS

Intra-ischaemic reductions of regional cerebral blood flow (rCBF) were similar in all groups (68-75% of baseline values). Reperfusion was significantly impaired in the 90-minute ischaemia group (56-62% vs 80-125% in other groups). Twenty minutes of t-MCAO induced a small infarct (3 ± 5% of ischaemic hemisphere). Thirty minutes of ischaemia produced a significantly larger infarct (46 ± 6%). In the 45 and 60 minute groups, ischaemia infarct was 52 ± 5% and 59 ± 3% of the ischaemic hemisphere, respectively. Ischaemia of 90' led to a massive stroke (89 ± 6% of ischaemic hemisphere encompassing the whole striatum (22 ± 3%) and almost the whole MCA irrigated cortex area (67 ± 6%)). Thirty minutes of t-MCAO did not produce stroke in the control group.

CONCLUSION

The diabetic rat stroke model should be different from the non-diabetic, because female type-1 diabetic SD rats are highly sensitive to brain ischaemia and it is necessary to significantly shorten the duration of t-MCAO, optimally to 30 minutes.

Enhancement in the Neuroprotective Power of Riluzole Against Cerebral Ischemia Using a Brain Targeted Drug Delivery Vehicle

Riluzole is the only available drug for motor neuron diseases quite well-known for its neuroprotective activity. But its poor aqueous solubility, short half-life with some side-effects at higher concentration poses a limitation to its use as a therapeutic agent. The present study was performed to investigate the therapeutic potential of nanoriluzole (NR), i.e., riluzole encapsulated in nanoparticles against cerebral ischemia (stroke) at three different concentrations [10 (NRL), 20 (NRM), and 40 (NRH) μg/kg body weight intraperitoneally (i.p.)]. Chitosan conjugated NIPAAM (N-isopropylacrylamide) nanoparticles coated with tween80 were synthesized through free radical polymerization. The particles were characterized with Transmission Electron Microscopy, Dynamic Light Scattering, and Fourier Transform Infrared spectroscopy and were found to have size of ∼50 nm. Cerebral ischemia was induced by Middle Cerebral Artery Occlusion (MCAO) model for 1 h and NR was given intraperitoneally after 1 h of MCAO. Animals were dissected after a reperfusion period of 24 h for evaluation of various parameters. Triphenyl tetrazolium chloride staining shows substantial reduction in infarct size in all three treated groups. It was also supported by histopathological results, biochemical parameters, and behavioral studies. Immunological parameters like NOS-2, NF-kB, and COX-2 also show profound reduction in expression in NR treated groups. Thus, the present work clearly demonstrated that the nanoparticle was good enough to carry large amount of drug across the Blood Brain Barrier which results in significant neuroprotection even at a very low concentration. It also substantially lowered the required concentration by overcoming the poor aqueous solubility; hence hardly leaving any scope for side-effects.

Non-invasive evaluation of neuroprotective drug candidates for cerebral infarction by PET imaging of mitochondrial complex-I activity

The development of a diagnostic technology that can accurately determine the pathological progression of ischemic stroke and evaluate the therapeutic effects of cerebroprotective agents has been desired. We previously developed a novel PET probe, 2-tert-butyl-4-chloro-5-{6-[2-(2-¹⁸F-fluoroethoxy)-ethoxy]-pyridin-3-ylmethoxy}-2H-pyridazin-3-one ([¹⁸F]BCPP-EF) for detecting activity of mitochondrial complex I (MC-I). This probe was shown to visualize neuronal damage in the living brain of rodent and primate models of neurodegenerative diseases. In the present study, [¹⁸F]BCPP-EF was applied to evaluate the therapeutic effects of a neuroprotectant, liposomal FK506 (FK506-liposomes), on cerebral ischemia/reperfusion (I/R) injury in transient middle cerebral artery occlusion rats. The PET imaging using [¹⁸F]BCPP-EF showed a prominent reduction in the MC-I activity in the ischemic brain hemisphere. Treatment with FK506-liposomes remarkably increased the uptake of [¹⁸F]BCPP-EF in the ischemic side corresponding to the improvement of blood flow disorders and motor function deficits throughout the 7 days after I/R. Additionally, the PET scan could diagnose the extent of the brain damage accurately and showed the neuroprotective effect of FK506-liposomes at Day 7, at which 2, 3, 5-triphenyltetrazolium chloride staining couldn’t visualize them. Our study demonstrated that the PET technology using [¹⁸F]BCPP-EF has a potent capacity to evaluate the therapeutic effect of drug candidates in living brain.

Blood-Spinal Cord Barrier Alterations in Subacute and Chronic Stages of a Rat Model of Focal Cerebral Ischemia

We previously demonstrated blood-brain barrier impairment in remote contralateral brain areas in rats at 7 and 30 days after transient middle cerebral artery occlusion (tMCAO), indicating ischemic diaschisis. Here, we focused on effects of subacute and chronic focal cerebral ischemia on the blood-spinal cord barrier (BSCB). We observed BSCB damage on both sides of the cervical spinal cord in rats at 7 and 30 days post-tMCAO. Major BSCB ultrastructural changes in spinal cord gray and white matter included vacuolated endothelial cells containing autophagosomes, pericyte degeneration with enlarged mitochondria, astrocyte end-feet degeneration and perivascular edema; damaged motor neurons, swollen axons with unraveled myelin in ascending and descending tracts and astrogliosis were also observed. Evans Blue dye extravasation was maximal at 7 days. There was immunofluorescence evidence of reduction of microvascular expression of tight junction occludin, upregulation of Beclin-1 and LC3B immunoreactivities at 7 days and a reduction of the latter at 30 days post-ischemia. These novel pathological alterations on the cervical spinal cord microvasculature in rats after tMCAO suggest pervasive and long-lasting BSCB damage after focal cerebral ischemia, and that spinal cord ischemic diaschisis should be considered in the pathophysiology and therapeutic approaches in patients with ischemic cerebral infarction.