Focal cerebral ischemia and mitochondrial dysfunction in the TNFα-transgenic rat

MyD88 Inhibition Attenuates Cerebral Ischemia-reperfusion Injury by Regulating the Inflammatory Response and Reducing Blood-brain Barrier Damage

Myeloid differentiation primary response gene 88 (MyD88), a downstream molecule directly linked to Toll-like receptor (TLRs) and IL1 receptor, has been implicated in ischemia-reperfusion injury across various organs. However, its role in cerebral ischemia-reperfusion injury (CIRI) remains unclear. Five transient middle cerebral artery occlusion (tMCAO) microarray datasets were obtained from the Gene Expression Omnibus (GEO) database. We screened these datasets for differentially expressed genes (DEGs) using the GSE35338 and GSE58720 datasets and performed weighted gene co-expression network analysis (WGCNA) using the GSE30655, GSE28731, and GSE32529 datasets to identify the core module related to tMCAO. A protein-protein interaction (PPI) network was constructed using the intersecting DEGs and genes in the core module. Finally, we identified Myd88 was the core gene. In addition, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Set Enrichment Analysis (GSEA) validated that TNFα, IL17, and MyD88 signaling pathways were significantly enriched in tMCAO. Subsequently, we investigated the mechanistic role of MyD88 in the tMCAO model using male C57BL/6 mice. MyD88 expression increased significantly 24 h after reperfusion. After intraperitoneal administration of TJ-M2010-5, a MyD88-specific inhibitor, during reperfusion, the infarction volumes in the mice were ameliorated. TJ-M2010-5 inhibits the activation of microglia and astrocytes. Moreover, it attenuates the upregulation of inflammatory cytokines TNFα, IL17, and MMP9 while preserving the expression level of ZO1 after tMCAO, thereby safeguarding against blood-brain barrier (BBB) disruption. Finally, our findings suggest that MyD88 regulates the IRAK4/IRF5 signaling pathway associated with microglial activation. MyD88 participates in CIRI by regulating the inflammatory response and BBB damage following tMCAO.

The alpha2-adrenergic receptor agonist clonidine protects against cerebral ischemia/reperfusion induced neuronal apoptosis in rats

Apoptosis is the crucial pathological mechanism following cerebral ischemic injury. Our previous studies demonstrated that clonidine, one agonist of alpha2-adrenergic receptor (α2-AR), could attenuate cerebral ischemic injury in a rat model of middle cerebral artery occlusion/reperfusion (MCAO/R). However, it's unclear whether clonidine exerts neuroprotective effects by regulating neuronal apoptosis. In this study, we elucidated whether clonidine can exert anti-apoptotic effects in cerebral ischemic injury, and further explored the possible mechanisms. Neurological deficit score was measured to evaluate the neurological function. TTC staining was used for the measurement of brain infarct size. Hematoxylin-Eosin (HE) staining was applied to examine the cell morphology. TUNEL and DAPI fluorescent staining methods were used to analyze the cell apoptosis in brain tissue. Fluorescence quantitative real-time PCR was performed to assess the gene expression of Caspase-3 and P53. Western blotting assay was applied to detect the protein expression of Caspase-3 and P53. The results showed that clonidine improved neurological function, reduced brain infarct size, alleviated neuronal damage, and reduced the ratio of cell apoptosis in the brain with MCAO/R injury. moreover, clonidine down-regulated the gene and protein expression of Caspase-3 and P53 which were over-expressed after MCAO/R injury. Whereas, yohimbine (one selective α2-AR antagonist) mitigated the anti-apoptosis effects of clonidine, accompanied by reversed gene and protein expression changes. The results indicated that clonidine attenuated cerebral MCAO/R injury via suppressing neuronal apoptosis, which may be mediated, at least in part, by activating α2-AR.

Comprehensive evaluation of mitochondrial redox profile, calcium dynamics, membrane integrity and apoptosis markers in a preclinical model of severe penetrating traumatic brain injury

Traumatic Brain Injury (TBI) is caused by the external physical assaults damages the brain. It is a heterogeneous disorder that remains a leading cause of death and disability in the military and civilian population of the United States. Preclinical investigations of mitochondrial responses in TBI have ascertained that mitochondrial dysfunction is an acute indicator of cellular damage and plays a pivotal role in long-term injury progression through cellular excitotoxicity. The current study was designed to provide an in-depth evaluation of mitochondrial endpoints with respect to redox and calcium homeostasis, and cell death responses following penetrating TBI (PTBI). To evaluate these pathological cascades, anesthetized adult male rats (N = 6/group) were subjected to either 10% unilateral PTBI or Sham craniectomy. Animals were euthanized at 24 h post-PTBI, and purified mitochondrial fractions were isolated from the brain injury core and perilesional areas. Overall, increased reactive oxygen and nitrogen species (ROS/RNS) production, and elevated oxidative stress markers such as 4-hydroxynonenal (4-HNE), 3-nitrotyrosine (3-NT), and protein carbonyls (PC) were observed in the PTBI group compared to Sham. Mitochondrial antioxidants such as glutathione, peroxiredoxin (PRX-3), thioredoxin (TRX), nicotinamide adenine dinucleotide phosphate (NADPH), superoxide dismutase (SOD), and catalase (CAT) levels were significantly decreased after PTBI. Likewise, PTBI mitochondria displayed significant loss of Ca²⁺ homeostasis, early opening of mitochondrial permeability transition pore (mPTP), and increased mitochondrial swelling. Both, outer and inner mitochondrial membrane integrity markers, such as voltage-dependent anion channels (VDAC) and cytochrome c (Cyt C) expression were significantly decreased following PTBI. The apoptotic cell death was evidenced by significantly decreased B-cell lymphoma-2 (Bcl-2) and increased glyceraldehyde 3-phosphate dehydrogenase (GAPDH) expression after PTBI. Collectively, current results highlight the comprehensive picture of mitochondria-centric acute pathophysiological responses following PTBI, which may be utilized as novel prognostic indicators of disease progression and theragnostic indicators for evaluating neuroprotection therapeutics following TBI.

Time-Course Evaluation of Brain Regional Mitochondrial Bioenergetics in a Pre-Clinical Model of Severe Penetrating Traumatic Brain Injury

Mitochondrial dysfunction is a pivotal target for neuroprotection strategies for traumatic brain injury (TBI). However, comprehensive time-course evaluations of mitochondrial dysfunction are lacking in the pre-clinical penetrating TBI (PTBI) model. The current study was designed to characterize temporal responses of mitochondrial dysfunction from 30 min to 2 weeks post-injury after PTBI. Anesthetized adult male rats were subjected to either PTBI or sham craniectomy (n = 6 animals per group × 7 time points). Animals were euthanized at 30 min, 3 h, 6 h, 24 h, 3 days, 7 days, and 14 days post-PTBI, and mitochondria were isolated from the ipsilateral hemisphere of brain regions near the injury core (i.e., frontal cortex [FC] and striatum [ST]) and a more distant region from the injury core (i.e., hippocampus [HIP]). Mitochondrial bioenergetics parameters were measured in real time using the high-throughput procedures of the Seahorse Flux Analyzer (Agilent Technologies, Santa Clara, CA). The post-injury time course of FC + ST showed a biphasic mitochondrial bioenergetics dysfunction response, indicative of reduced adenosine triphosphate synthesis rate and maximal respiratory capacity after PTBI. An initial phase of energy crisis was detected at 30 min (-42%; p < 0.05 vs. sham), which resolved to baseline levels between 3 and 6 h (non-significant vs. sham). This was followed by a second and more robust phase of bioenergetics dysregulation detected at 24 h that remained unresolved out to 14 days post-injury (-55% to -90%; p < 0.05 vs. sham). In contrast, HIP mitochondria showed a delayed onset of mitochondrial dysfunction at 7 days (-74%; p < 0.05 vs. sham) that remained evident out to 14 days (-51%; p < 0.05 vs. sham) post-PTBI. Collectively, PTBI-induced mitochondrial dysfunction responses were time and region specific, evident differentially at the injury core and distant region of PTBI. The current results provide the basis that mitochondrial dysfunction may be targeted differentially based on region specificity post-PTBI. Even more important, these results suggest that therapeutic interventions targeting mitochondrial dysfunction may require extended dosing regimens to achieve clinical efficacy after TBI.

Preconditioning with L-Ala-Gln reduces the expression of inflammatory markers (TNF-α, NF-κB, IL-6 and HO-1) in an injury animal model of cerebrovascular ischemia in Meriones unguiculatus (gerbils)

Purpose

To evaluate the neuroprotective effect of L-alanyl-glutamine in a gerbil model of brain ischemia-reperfusion injury based on immunohistochemical quantification of pro-inflammatory and cell activation biomarkers (TNF-α, NF-κB, IL-6 and HO-1).

Methods

Male gerbils weighing 100-180 g were pretreated with either 0.75 g/kg L-Ala-Gln (n=18) or 2.0 mL saline (n=18) administered i.v. 30 minutes before the bilateral ligation of the common carotid artery during 15 min and then the ligation was removed. Under anesthesia with urethane, brain tissue was harvested at 0 min (T₀), 30 min (T₃₀) and 60 min (T₆₀) after reperfusion. The tissue was embedded in 10% formalin overnight and 4-μm sections were prepared for immunostaining with monoclonal antibodies. Immunostained cells were counted by optical microscopy. The statistical analysis used mean values based on 4 sections.

Results

The pretreatment with L-Ala-Gln animal group 1 demonstrated significantly lower levels of TNF-α, NF-κB and IL-6. On the other hand, the levels of HO-1 were significantly higher, suggesting a protective role in model of brain ischemia-reperfusion injury.

Conclusion

These findings suggest a protective effect of L-Ala-Gln by decreasing levels of TNF-alpha, IL-6 and NF-κB and Increasing levels of HO-1.

Ponatinib-induced ischemic stroke in larval zebrafish for drug screening

Conventional mammalian ischemic stroke models for drug screening are technically challenging, laborious and time-consuming. In this study, using Ponatinib as an inducer, we developed and characterized a zebrafish ischemic stroke model. This zebrafish ischemic stroke had the cerebral vascular endothelial injury, thrombosis, reduced blood flow, inflammation and apoptosis as well as the reduced motility. The zebrafish ischemic stroke model was validated with 6 known human therapeutic drugs of ischemic stroke (Aspirin, Clopidogrel, Naoxintong capsules, Edaravone, Xingnaojing injection, Shuxuening injection). The mRNA levels of the neovascularization-related gene (vegfaa) and vascular endothelial growth factor receptor gene (VEGFR), neurodevelopment related genes (mbp and α1-tubulin), brain-derived neurotrophic factor (BDNF) and glial cell derived neurotrophic factor (GDNF) were significantly downregulated; whereas apoptosis-related genes (caspase-3, caspase-7, caspase-9 and bax/bcl-2), and inflammatory factor genes (IL-1β, IL-6, IL-10, TNF-α and NF-κB) were remarkably upregulated in the model. These results suggest that the pathophysiology of Ponatinib-induced zebrafish ischemic stroke is similar to that of human ischemic stroke patients and this whole animal model could be used to study the complex cellular and molecular pathogenesis of ischemic stroke and to rapidly identify therapeutic agents.

Formoterol, a β2-adrenoreceptor agonist, induces mitochondrial biogenesis and promotes cognitive recovery after traumatic brain injury

Traumatic brain injury (TBI) leads to acute necrosis at the site of injury followed by a sequence of secondary events lasting from hours to weeks and often years. Targeting mitochondrial impairment following TBI has shown improvements in brain mitochondrial bioenergetics and neuronal function. Recently formoterol, a highly selective β₂-adrenoreceptor agonist, was found to induce mitochondrial biogenesis (MB) via Gβγ-Akt-eNOS-sGC pathway. Activation of MB is a novel approach that has been shown to restore mitochondrial function in several disease and injury models. We hypothesized that activation of MB as a target of formoterol after TBI would mitigate mitochondrial dysfunction, enhance neuronal function and improve behavioral outcomes. TBI-injured C57BL/6 male mice were injected (i.p.) with vehicle (normal saline) or formoterol (0.3 mg/kg) at 15 min, 8 h, 16 h, 24 h and then daily after controlled cortical impact (CCI) until euthanasia. After CCI, mitochondrial copy number and bioenergetic function were decreased in the ipsilateral cortex of the CCI-vehicle group. Compared to CCI-vehicle, cortical and hippocampal mitochondrial respiration rates as well as cortical mitochondrial DNA copy number were increased in the CCI-formoterol group. Mitochondrial Ca²⁺ buffering capacity in the hippocampus was higher in the CCI-formoterol group compared to CCI-vehicle group. Both assessments of cognitive performance, novel object recognition (NOR) and Morris water maze (MWM), decreased following CCI and were restored in the CCI-formoterol group. Although no changes were seen in the amount of cortical tissue spared between CCI-formoterol and CCI-vehicle groups, elevated levels of hippocampal neurons and improved white matter sparing in the corpus callosum were observed in CCI-formoterol group. Collectively, these results indicate that formoterol-mediated MB activation may be a potential therapeutic target to restore mitochondrial bioenergetics and promote functional recovery after TBI.

Age- and Organ-Specific Differences in Mitochondrial Bioenergetics in Brown Norway Rats

Mitochondria play a central role in energy homeostasis and act as regulatory checkpoints for downstream metabolic responses and cell senescence processes during an entire life span. Acute or chronic environmental toxicant exposures have shown deleterious organ-specific human health issues at various life stages. Since mitochondria are a prime target for ensuing cellular bioenergetics responses and senescence, it is essential to understand mitochondrial bioenergetic responses in different organs over multiple life stages. Therefore, in the present study, we evaluated mitochondrial bioenergetic parameters in the liver, lung, and heart in four diverse age groups (young: 1 month; adult: 4 months; middle-aged: 12 months; old-aged: 24 month) using male Brown Norway rats as a model of aging (n = 5 sample size/organ/age group) and compared them with our previously published results on brain. Real-time mitochondrial bioenergetic parameters (i.e., State III, State IV, and State V) were measured using the Seahorse Extracellular Flux Analyzer. Additionally, mitochondrial enzyme pyruvate dehydrogenase complex (PDHC), Complex I, Complex II, and Complex IV activities were measured using Synergy HT plate reader. Our results indicated that nearly in all parameters, significant age- and organ-specific interactions were observed. We observed age-specific declines in State III (i.e., ATP synthesis rate) responses in both the heart and lung, where opposite was observed in the liver as age advances. Across the age, the heart has highest enzyme activities than the liver and lung. Interestingly, heart and liver mitochondrial bioenergetic rates and enzyme activities remain higher than the lung, which specifies their higher metabolic capabilities than the lung. Amongst all, bioenergetic rates and enzyme activities in the lung remain lowest suggesting the lung may display higher vulnerability and lower resilience to environmental toxicants during aging than other organs tested here. Overall, these age- and organ-specific findings may facilitate a more contextualized understanding of mitochondrial bioenergetic outcomes when considering the interactions of age-related sensitivities with exposure to chemical stressors from the environment.

Measuring Respiration in Isolated Murine Brain Mitochondria: Implications for Mechanistic Stroke Studies

Measuring mitochondrial respiration in brain tissue is very critical in understanding the physiology and pathology of the central nervous system. Particularly, measurement of respiration in isolated mitochondria provides the advantage over the whole cells or tissues as the changes in respiratory function are intrinsic to mitochondrial structures rather than the cellular signaling that regulates mitochondria. Moreover, a high-throughput technique for measuring mitochondrial respiration minimizes the experimental time and the sample-to-sample variation. Here, we provide a detailed protocol for measuring respiration in isolated brain non-synaptosomal mitochondria using Agilent Seahorse XFe24 Analyzer. We optimized the protocol for the amount of mitochondria and concentrations of ADP, oligomycin, and trifluoromethoxy carbonylcyanide phenylhydrazone (FCCP) for measuring respiratory parameters for complex I-mediated respiration. In addition, we measured complex II-mediated respiratory parameters. We observed that 10 µg of mitochondrial protein per well, ADP concentrations ranging between 2.5 and 10 mmol/L along with 5 µmol/L of oligomycin, and 5 µmol/L of FCCP are ideal for measuring the complex I-mediated respiration in isolated mouse brain mitochondria. Furthermore, we determined that 2.5 µg of mitochondrial protein per well is ideal for measuring complex II-mediated respiration. Notably, we provide a discussion of logical analysis of data and how the assay could be utilized to design mechanistic studies for experimental stroke. In conclusion, we provide detailed experimental design for measurement of various respiratory parameters in isolated brain mitochondria utilizing a novel high-throughput technique along with interpretation and analysis of data.

Brain mitochondrial bioenergetics change with rapid and prolonged shifts in aggression in the honey bee, Apis mellifera

Neuronal function demands high-level energy production, and as such, a decline in mitochondrial respiration characterizes brain injury and disease. A growing number of studies, however, link brain mitochondrial function to behavioral modulation in non-diseased contexts. In the honey bee, we show for the first time that an acute social interaction, which invokes an aggressive response, may also cause a rapid decline in brain mitochondrial bioenergetics. The degree and speed of this decline has only been previously observed in the context of brain injury. Furthermore, in the honey bee, age-related increases in aggressive tendency are associated with increased baseline brain mitochondrial respiration, as well as increased plasticity in response to metabolic fuel type in vitro. Similarly, diet restriction and ketone body feeding, which commonly enhance mammalian brain mitochondrial function in vivo, cause increased aggression. Thus, even in normal behavioral contexts, brain mitochondria show a surprising degree of variation in function over both rapid and prolonged timescales, with age predicting both baseline function and plasticity in function. These results suggest that mitochondrial function is integral to modulating aggression-related neuronal signaling. We hypothesize that variation in function reflects mitochondrial calcium buffering activity, and that shifts in mitochondrial function signal to the neuronal soma to regulate gene expression and neural energetic state. Modulating brain energetic state is emerging as a critical component of the regulation of behavior in non-diseased contexts.

Nobiletin improves propofol-induced neuroprotection via regulating Akt/mTOR and TLR 4/NF-κB signaling in ischemic brain injury in rats

BACKGROUND

Stroke is regarded as one of the main health concerns globally, presenting with high mortality and morbidity rates. Cerebral ischemic damage and infarction are critically associated with stroke. Various mechanisms related to inflammation, oxidative stress and excitotoxicity are found to be involved in ischemic damage. Very short time period for treatment has necessitated in development of more effective neuroprotective agents. Study aimed in investigated the effects of nobiletin on experimentally induced ischemic brain injury and also to assess whether nobiletin potentiated the neuroprotective effects of propofol.

METHODS

Male Sprague-Dawley rats were subjected to ischemia/reperfusion (I/R) injury. Induction of cerebral infarction and I/R was done by middle cerebral artery occlusion (MCAO). Nobiletin (100 or 200mg/kg b.wt.) was intragastrically administered to rats for 9 days before ischemia induction and on the day of induction nobiletin was administered an hour prior. Separate group of rats were post-conditioned with propofol (50mg/kg/h; i.v.) for 30min following 24h of reperfusion.

RESULTS

Propofol post-conditioning either with or without administration of nobiletin prior I/R injury attenuated pulmonary edema, neuronal apoptosis and reduced cerebral infarct volume. Overproduction of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) and nitric oxide following I/R were reduced. Propofol either alone or with prior nobiletin treatment had down-regulated TLR4 and TLR4-mediated NF-κB signaling and caused activation of Akt/mTOR cascade.

CONCLUSION

Propofol post-conditioning either with nobiletin prior I/R injury was found to be more effective than propofol alone, suggesting the positive effects of nobiletin on propofol-mediated anti-inflammatory and neuroprotective effects.

Plumbagin inhibits neuronal apoptosis, intimal hyperplasia and also suppresses TNF-α/NF-κB pathway induced inflammation and matrix metalloproteinase-2/9 expression in rat cerebral ischemia

Cerebral ischemic damage and infarction are well documented in stroke, which is presenting a foremost health concern globally with very high mortality and morbidity rates. Mechanisms that are associated with excitotoxicity, inflammation and oxidative stress are found to be critically involved in ischemic damage. Adverse effects of current therapies are imposing the need in development of neuroprotective agents that are very effective. To explore this we experimentally induced ischemic brain injury and investigated the effects of plumbagin. Induction of cerebral infarction and ischemia-reperfusion (I/R) was done by middle cerebral artery occlusion (MCAO) in Sprague-Dawley rats. Plumbagin (50, 100 or 200 mg/kg b.wt) was intragastrically administered for 9 days before ischemia induction and an hour prior on the day of ischemic insult. Plumbagin treatment attenuated pulmonary edema, neuronal apoptosis and reduced cerebral infarct volume. Cleaved caspase-3 and apoptotic cascade protein expressions were regulated. Overproduction of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) and nitric oxide (NO) following I/R were reduced. Prior plumbagin administration had down-regulated NF-κB signalling and MMP-2 and MMP-9 expression. Overall, the results reveal the potent neuroprotective efficacy of plumbagin against I/R-induced brain injury via effectively modulating apoptotic pathways, MMPs and neuro-inflammatory cascades.

Hydroxyapatite nanoparticle-induced mitochondrial energy metabolism impairment in liver cells: in vitro and in vivo studies

Hydroxyapatite nanoparticles (HAP-NPs) have been extensively developed as drug carriers, bone implants, coating materials, etc. in the human body. However, research focusing on the potential side effects of HAP-NPs on the mitochondria-associated energy metabolism in liver cells is lacking. In this study, HAP-NPs with a long diameter of 80 nm and a short diameter of 20 nm were evaluated for their ability to induce mitochondrial energy metabolism dysfunction in vitro and in vivo. In the in vitro system, the buffalo rat hepatocyte (BRL) cell line was directly exposed to the HAP-NPs. The results of these experiments showed that the HAP-NPs induced inhibition of mitochondrial dehydrogenase activity, which was accompanied by a decrease in the mitochondrial membrane potential (MMP). In addition, HAP-NPs elevated the hepatic levels of reactive oxygen species (ROS) and malondialdehyde (MDA) and decreased the levels of GSH and SOD. These data indicated that HAP-NPs induced a lowered rate of electron transfer in the mitochondrial respiratory chain, accompanied by a decrease in the activity of the mitochondrial respiratory chain complexes I, II and III. Furthermore, HAP-NPs induced a decline in the enzymatic expression in the Krebs cycle. We also investigated the role of Kupffer cells (KCs, rat-derived) in the effects induced by the HAP-NPs. The supernatant from the HAP-NP-treated KCs was used to stimulate the BRL cells. We observed that the HAP-NPs had the ability to induce KC activation. The activation of KCs then led to the release of tumor necrosis factor-α (TNF-α), nitric oxide (NO) and reactive oxygen species (ROS), and induced the inhibition of mitochondrial respiratory chain complexes I, II and III in the BRL cells. In the in vivo study, the TEM examination revealed mitochondrial swelling and vacuolar degeneration in the HAP-NP-treated hepatocytes. In addition, the amount of succinate (Suc), an intermediate in the mitochondrial Krebs cycle, also declined in the ¹ H NMR spectroscopic measurements. Copyright © 2017 John Wiley & Sons, Ltd.

Protection against cerebral infarction by Withaferin A involves inhibition of neuronal apoptosis, activation of PI3K/Akt signaling pathway, and reduced intimal hyperplasia via inhibition of VSMC migration and matrix metalloproteinases

PURPOSE

Stroke is a major public health concern with high rates of morbidity and mortality worldwide. Cerebral ischemia and infarction are commonly associated with stroke. Currently used medications, though effective, are also associated with adverse effects. Development of effective neuroprotective agents with fewer side effects would be of clinical value. We evaluated the effects of Withaferin A (WA), a steroidal lactone derived from the plant Withania somnifera, on experimentally induced cerebral infarction.

MATERIALS AND METHODS

The ability of WA to inhibit neuroapoptosis and modulate vascular smooth muscle cell (VSMC) migration and PI3K/Akt signaling was assessed. Separate groups of Sprague Dawley rats were subjected to cerebral occlusion and reperfused for 24h.

RESULTS

WA treatment (25, 50 or 100mg/kg bodyweight) significantly reduced the infarct area in a carotid ligation model; WA reduced intimal hyperplasia and proliferating cell nuclear antigen (PCNA)-positive cell counts. Western blotting analysis revealed significantly suppressed PI3K/Akt signaling following cerebral ischemia/reperfusion injury. WA supplementation was found to downregulate apoptotic pathway proteins. WA suppressed PTEN and enhanced p-Akt and GSK-3β levels and elevated mTORc1, cyclinD1 and NF-κB p65 expression, suggesting activation of the PI3K/Akt pathway. In vitro studies with PDGF-stimulated A7r5 cells revealed that WA exposure severely downregulated matrix metalloproteinases (MMP)-2 and -9 and inhibited migration of A7r5 cells. Additionally, WA reduced the proliferation of A7r5 cells significantly.

CONCLUSIONS

WA exerted neuroprotective effects by activating the PI3K/Akt pathway, modulating the expression of MMPs, and inhibiting the migration of VSMCs.

Proteomic Analysis of a Rat Cerebral Ischemic Injury Model after Human Cerebral Endothelial Cell Transplantation

Objective

Cerebral endothelial cells have unique biological features and are fascinating candidate cells for stroke therapy.

Methods

In order to understand the molecular mechanisms of human cerebral endothelial cell (hCMEC/D3) transplantation in a rat stroke model, we performed proteomic analysis using 2-dimensional electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Protein expression was confirmed by quantitative real-time PCR and Western blot.

Results

Several protein spots were identified by gel electrophoresis in the sham, cerebral ischemia (CI), and CI with hCMEC/D3 treatment cerebral ischemia with cell transplantation (CT) groups, and we identified 14 differentially expressed proteins in the CT group. Proteins involved in mitochondrial dysfunction (paraplegin matrix AAA peptidase subunit, SPG7), neuroinflammation (peroxiredoxin 6, PRDX6), and neuronal death (zinc finger protein 90, ZFP90) were markedly reduced in the CT group compared with the CI group. The expression of chloride intracellular channel 4 proteins involved in post-ischemic vasculogenesis was significantly decreased in the CI group but comparable to sham in the CT group.

Conclusion

These results contribute to our understanding of the early phase processes that follow cerebral endothelial cell treatment in CI. Moreover, some of the identified proteins may present promising new targets for stroke therapy.

Neuroprotective effects of Kaempferide-7-O-(4″-O-acetylrhamnosyl)-3-O-rutinoside on cerebral ischemia-reperfusion injury in rats

In the present study, we aim to evaluate the potential neuroprotective effect and the underlying mechanism of Kaempferide-7-O-(4″-O-acetylrhamnosyl)-3-O-rutinoside (A-F-B) against cerebral I/R injury. Adult male rats were pretreated with A-F-B by intragastric administration once a day for 3 days. One hour after the third day administration, animals were subjected to 2h of transient middle cerebral artery occlusion (MCAO) followed by 24h of reperfusion. Neurological deficit, infarct volume, histopathological changes, oxidative stress-related biochemical parameters, neuronal apoptosis, apoptosis-related proteins and the expression of pro-inflammator cytokines genes were measured. A-F-B significantly decreased neurological and histological deficits, reduced the infarct volume, and decreased neuroapoptosis. Meanwhile, A-F-B inhibited the expression of Bax, cleaved caspase-3, cleaved caspase-9, and promoted Bcl-2 expression. In addition, the expression of pro-inflammator cytokines, including phospho-NF-kBp65, interleukin-1β, interleukin-6, tumor necrosis factor-α, intercellular adhesion molecule-1, cyclooxygenase-2 and inducible nitric oxide synthase, were also suppressed by A-F-B pretreatment. Furthermore, pretreatment with A-F-B could significantly increase the activities of superoxide dismutase, glutathione peroxidase, but decrease the content of malondiadehyde in blood serum. These results suggest that A-F-B has the neuroprotective effect in ischemic stroke by suppressing neuroinflammation, reactive oxygen species and neuroapoptosis.

Age- and brain region-specific differences in mitochondrial bioenergetics in Brown Norway rats

Mitochondria are central regulators of energy homeostasis and play a pivotal role in mechanisms of cellular senescence. The objective of the present study was to evaluate mitochondrial bioenergetic parameters in 5 brain regions (brain stem [BS], frontal cortex, cerebellum, striatum, hippocampus [HIP]) of 4 diverse age groups (1 month [young], 4 months [adult], 12 months [middle-aged], 24 months [old age]) to understand age-related differences in selected brain regions and their possible contribution to age-related chemical sensitivity. Mitochondrial bioenergetic parameters and enzyme activities were measured under identical conditions across multiple age groups and brain regions in Brown Norway rats (n = 5/group). The results indicate age- and brain region-specific patterns in mitochondrial functional endpoints. For example, an age-specific decline in ATP synthesis (State III respiration) was observed in BS and HIP. Similarly, the maximal respiratory capacities (State V1 and V2) showed age-specific declines in all brain regions examined (young > adult > middle-aged > old age). Amongst all regions, HIP had the greatest change in mitochondrial bioenergetics, showing declines in the 4, 12, and 24-months age groups. Activities of mitochondrial pyruvate dehydrogenase complex and electron transport chain complexes I, II, and IV enzymes were also age and brain region specific. In general, changes associated with age were more pronounced with enzyme activities declining as the animals aged (young > adult > middle-aged > old age). These age- and brain region-specific observations may aid in evaluating brain bioenergetic impact on the age-related susceptibility to environmental chemical stressors.

Decreased mitochondrial bioenergetics and calcium buffering capacity in the basal ganglia correlates with motor deficits in a nonhuman primate model of aging

Altered mitochondrial function in the basal ganglia has been hypothesized to underlie cellular senescence and promote age-related motor decline. We tested this hypothesis in a nonhuman primate model of human aging. Six young (6-8 years old) and 6 aged (20-25 years old) female Rhesus monkeys (Macaca mulatta) were behaviorally characterized from standardized video records. Additionally, we measured mitochondrial bioenergetics along with calcium buffering capacity in the substantia nigra and putamen (PUT) from both age groups. Our results demonstrate that the aged animals had significantly reduced locomotor activity and movement speed compared with younger animals. Moreover, aged monkeys had significantly reduced ATP synthesis capacity (in substantia nigra and PUT), reduced pyruvate dehydrogenase activity (in PUT), and reduced calcium buffering capacity (in PUT) compared with younger animals. Furthermore, this age-related decline in mitochondrial function in the basal ganglia correlated with decline in motor function. Overall, our results suggest that drug therapies designed to enhance altered mitochondrial function may help improve motor deficits in the elderly.

Buyang Huanwu Decoction fraction protects against cerebral ischemia/reperfusion injury by attenuating the inflammatory response and cellular apoptosis

Buyang Huanwu Decoction fraction extracted from Buyang Huanwu Decoction contains saponins of Astragalus, total paeony glycoside and safflower flavones. The aim of this study was to demonstrate the neuroprotective effect and mechanism of Buyang Huanwu Decoction fraction on ischemic injury both in vivo and in vitro. In vivo experiments showed that 50-200 mg/kg Buyang Huanwu Decoction fraction reduced infarct volume and pathological injury in ischemia/reperfusion rats, markedly inhibited expression of nuclear factor-κB and tumor necrosis factor-α and promoted nestin protein expression in brain tissue. Buyang Huanwu Decoction fraction (200 mg/kg) exhibited significant effects, which were similar to those of 100 mg/kg Ginkgo biloba extract. In vitro experimental results demonstrated that 10-100 mg/L Buyang Huanwu Decoction fraction significantly improved cell viability, decreased the release of lactate dehydrogenase and malondialdehyde levels, and inhibited the rate of apoptosis in HT22 cells following oxygen-glucose deprivation. Buyang Huanwu Decoction fraction (100 mg/L) exhibited significant effects, which were similar to those of 100 mg/L Ginkgo biloba extract. These findings suggest that Buyang Huanwu Decoction fraction may represent a novel, protective strategy against cerebral ischemia/reperfusion injury in rats and oxygen-glucose deprivation-induced damage in HT22 cells in vitro by attenuating the inflammatory response and cellular apoptosis.

TNF and TNF-receptors: From mediators of cell death and inflammation to therapeutic giants - past, present and future

Tumor Necrosis Factor (TNF), initially known for its tumor cytotoxicity, is a potent mediator of inflammation, as well as many normal physiological functions in homeostasis and health, and anti-microbial immunity. It also appears to have a central role in neurobiology, although this area of TNF biology is only recently emerging. Here, we review the basic biology of TNF and its normal effector functions, and discuss the advantages and disadvantages of therapeutic neutralization of TNF - now a commonplace practice in the treatment of a wide range of human inflammatory diseases. With over ten years of experience, and an emerging range of anti-TNF biologics now available, we also review their modes of action, which appear to be far more complex than had originally been anticipated. Finally, we highlight the current challenges for therapeutic intervention of TNF: (i) to discover and produce orally delivered small molecule TNF-inhibitors, (ii) to specifically target selected TNF producing cells or individual (diseased) tissue targets, and (iii) to pre-identify anti-TNF treatment responders. Although the future looks bright, the therapeutic modulation of TNF now moves into the era of personalized medicine with society's challenging expectations of durable treatment success and of achieving long-term disease remission.

SiO₂ nanoparticle-induced impairment of mitochondrial energy metabolism in hepatocytes directly and through a Kupffer cell-mediated pathway in vitro

The liver has been shown to be a primary target organ for SiO₂ nanoparticles in vivo, and may be highly susceptible to damage by these nanoparticles. However, until now, research focusing on the potential toxic effects of SiO₂ nanoparticles on mitochondria-associated energy metabolism in hepatocytes has been lacking. In this work, SiO₂ nanoparticles 20 nm in diameter were evaluated for their ability to induce dysfunction of mitochondrial energy metabolism. First, a buffalo rat liver (BRL) cell line was directly exposed to SiO₂ nanoparticles, which induced cytotoxicity and mitochondrial damage accompanied by decreases in mitochondrial dehydrogenase activity, mitochondrial membrane potential, enzymatic expression in the Krebs cycle, and activity of the mitochondrial respiratory chain complexes I, III and IV. Second, the role of rat-derived Kupffer cells was evaluated. The supernatants from Kupffer cells treated with SiO₂ nanoparticles were transferred to stimulate BRL cells. We observed that SiO₂ nanoparticles had the ability to activate Kupffer cells, leading to release of tumor necrosis factor-α, nitric oxide, and reactive oxygen species from these cells and subsequently to inhibition of mitochondrial respiratory chain complex I activity in BRL cells.

Short-term preoperative dietary restriction is neuroprotective in a rat focal stroke model

Stroke is a major complication of cardiovascular surgery, resulting in over 100,000 deaths and over a million postoperative encephalopathies annually in the US and Europe. While mitigating damage from stroke after it occurs has proven elusive, opportunities to reduce the incidence and/or severity of stroke prior to surgery in at-risk individuals remain largely unexplored. We tested the potential of short-term preoperative dietary restriction to provide neuroprotection in rat models of focal stroke. Rats were preconditioned with either three days of water-only fasting or six days of a protein free diet prior to induction of transient middle cerebral artery occlusion using two different methods, resulting in either a severe focal stroke to forebrain and midbrain, or a mild focal stroke localized to cortex only. Infarct volume, functional recovery and molecular markers of damage and protection were assessed up to two weeks after reperfusion. Preoperative fasting for 3 days reduced infarct volume after severe focal stroke. Neuroprotection was associated with modulation of innate immunity, including elevation of circulating neutrophil chemoattractant C-X-C motif ligand 1 prior to ischemia and suppression of striatal pro-inflammatory markers including tumor necrosis factor α, its receptor and downstream effector intercellular adhesion molecule-1 after reperfusion. Similarly, preoperative dietary protein restriction for 6 days reduced ischemic injury and improved functional recovery in a milder cortical infarction model. Our results suggest that short-term dietary restriction regimens may provide simple and translatable approaches to reduce perioperative stroke severity in high-risk elective vascular surgery.

Concentration dependent effect of calcium on brain mitochondrial bioenergetics and oxidative stress parameters

Mitochondrial dysfunction following traumatic brain and spinal cord injury (TBI and SCI) plays a pivotal role in the development of secondary pathophysiology and subsequent neuronal cell death. Previously, we demonstrated a loss of mitochondrial bioenergetics in the first 24 h following TBI and SCI initiates a rapid and extensive necrotic event at the primary site of injury. Within the mitochondrial derived mechanisms, the cross talk and imbalance amongst the processes of excitotoxicity, Ca²⁺ cycling/overload, ATP synthesis, free radical production and oxidative damage ultimately lead to mitochondrial damage followed by neuronal cell death. Mitochondria are one of the important organelles that regulate intracellular calcium (Ca²⁺) homeostasis and are equipped with a tightly regulated Ca²⁺ transport system. However, owing to the lack of consensus and the link between downstream effects of calcium in published literature, we undertook a systematic in vitro study for measuring concentration dependent effects of calcium (100–1000 nmols/mg mitochondrial protein) on mitochondrial respiration, enzyme activities, reactive oxygen/nitrogen species (ROS/RNS) generation, membrane potential (ΔΨ) and oxidative damage markers in isolated brain mitochondria. We observed a dose- and time-dependent inhibition of mitochondrial respiration by calcium without influencing mitochondrial pyruvate dehydrogenase complex (PDHC) and NADH dehydrogenase (Complex I) enzyme activities. We observed dose-dependent decreased production of hydrogen peroxide and total ROS/RNS species generation by calcium and no significant changes in protein and lipid oxidative damage markers. These results may shed new light on the prevailing dogma of the direct effects of calcium on mitochondrial bioenergetics, free radical production and oxidative stress parameters that are primary regulatory mitochondrial mechanisms following neuronal injury.

Polyphenols: multipotent therapeutic agents in neurodegenerative diseases

Aging leads to numerous transitions in brain physiology including synaptic dysfunction and disturbances in cognition and memory. With a few clinically relevant drugs, a substantial portion of aging population at risk for age-related neurodegenerative disorders require nutritional intervention. Dietary intake of polyphenols is known to attenuate oxidative stress and reduce the risk for related neurodegenerative diseases such as Alzheimer's disease (AD), stroke, multiple sclerosis (MS), Parkinson's disease (PD), and Huntington's disease (HD). Polyphenols exhibit strong potential to address the etiology of neurological disorders as they attenuate their complex physiology by modulating several therapeutic targets at once. Firstly, we review the advances in the therapeutic role of polyphenols in cell and animal models of AD, PD, MS, and HD and activation of drug targets for controlling pathological manifestations. Secondly, we present principle pathways in which polyphenol intake translates into therapeutic outcomes. In particular, signaling pathways like PPAR, Nrf2, STAT, HIF, and MAPK along with modulation of immune response by polyphenols are discussed. Although current polyphenol researches have limited impact on clinical practice, they have strong evidence and testable hypothesis to contribute clinical advances and drug discovery towards age-related neurological disorders.

Calpain cleaves methionine aminopeptidase-2 in a rat model of ischemia/reperfusion

Ischemic stroke results in multiple injurious signals within a cell including dysregulation of calcium homeostasis. Consequently, there is an increase in the enzymatic activity of the calpains, calcium dependent proteases that are thought to contribute to neuronal injury. In addition, cellular stress due to ischemia/reperfusion also triggers a decrease in protein translation through activation of the unfolded protein response (UPR). In the present study we found that methionine aminopeptidase 2 (MetAP2), a critical component of the translation initiation complex, is a calpain substrate. In vitro calpain assays demonstrated that while MetAP2 has autoproteolytic activity, calpain also produces a stable proteolytic fragment at 50kDa using recombinant MetAP2. This 50kDa fragment, in addition to a 57kDa fragment was present in in vitro digestions of rat brain homogenates. Production of these fragments was inhibited by calpastatin, the endogenous and specific inhibitor of calpain. Using an in vivo middle cerebral artery occlusion (MCAO) model only the 57kDa fragment of MetAP2 was observed. These data suggest that calpain activation in stroke may regulate MetAP2-mediated protein translation giving calpains a larger role in the cellular stress response than previously determined.

Asiatic acid attenuates infarct volume, mitochondrial dysfunction, and matrix metalloproteinase-9 induction after focal cerebral ischemia

BACKGROUND AND PURPOSE

Asiatic acid (AA) has been shown to attenuate cerebral infarction in a mouse model of focal ischemia and shows promise as a neuroprotective stroke therapy. To facilitate translation of these findings to clinical studies, we determined pharmacokinetics, a dose-response relationship, the therapeutic time window, and efficacy using multiple stroke models. We also explored potential mechanisms of action.

METHODS

Escalating doses of intravenous AA were administered and serum concentrations were measured at multiple time points for the pharmacokinetic studies. Subsequently, a dose-response relationship was determined followed by administration at different intervals after the onset of ischemia to establish a therapeutic time window for neuroprotection. Outcome measurements included both histological and behavioral. Mitochondrial function and matrix metalloproteinase activity in controls and treated rats were also determined.

RESULTS

The pharmacokinetic studies showed that AA (75 mg/kg) has a half-life of 2.0 hours. AA significantly decreased infarct volume and improved neurological outcome even when administration was at time points up to 12 hours after the onset of ischemia. Infarct volume was also significantly decreased in female rats and spontaneously hypertensive rats. AA attenuated mitochondrial dysfunction and reduced matrix metalloproteinase-9 induction.

CONCLUSIONS

Our study shows AA is effective against multiple models of focal ischemia, has a long therapeutic time window, and is also effective in females and hypertensive animals. AA may mediate neuroprotection by protecting mitochondria and inhibiting matrix metalloproteinase-9 induction and activation. Taken together these data suggest that AA is an excellent candidate for development as a stroke therapy.