A novel quantitative EEG injury measure of global cerebral ischemia

Hypoxia-preconditioned bone marrow-derived mesenchymal stem cells protect neurons from cardiac arrest-induced pyroptosis

JOURNAL/nrgr/04.03/01300535-202504000-00027/figure1/v/2024-07-06T104127Z/r/image-tiff Cardiac arrest can lead to severe neurological impairment as a result of inflammation, mitochondrial dysfunction, and post-cardiopulmonary resuscitation neurological damage. Hypoxic preconditioning has been shown to improve migration and survival of bone marrow-derived mesenchymal stem cells and reduce pyroptosis after cardiac arrest, but the specific mechanisms by which hypoxia-preconditioned bone marrow-derived mesenchymal stem cells protect against brain injury after cardiac arrest are unknown. To this end, we established an in vitro co-culture model of bone marrow-derived mesenchymal stem cells and oxygen-glucose deprived primary neurons and found that hypoxic preconditioning enhanced the protective effect of bone marrow stromal stem cells against neuronal pyroptosis, possibly through inhibition of the MAPK and nuclear factor κB pathways. Subsequently, we transplanted hypoxia-preconditioned bone marrow-derived mesenchymal stem cells into the lateral ventricle after the return of spontaneous circulation in an 8-minute cardiac arrest rat model induced by asphyxia. The results showed that hypoxia-preconditioned bone marrow-derived mesenchymal stem cells significantly reduced cardiac arrest-induced neuronal pyroptosis, oxidative stress, and mitochondrial damage, whereas knockdown of the liver isoform of phosphofructokinase in bone marrow-derived mesenchymal stem cells inhibited these effects. To conclude, hypoxia-preconditioned bone marrow-derived mesenchymal stem cells offer a promising therapeutic approach for neuronal injury following cardiac arrest, and their beneficial effects are potentially associated with increased expression of the liver isoform of phosphofructokinase following hypoxic preconditioning.

ML218 modulates calcium binding protein, oxidative stress, and inflammation during ischemia-reperfusion brain injury in mice

Cerebral ischemia disrupts calcium homeostasis in the brain causing excitotoxicity, oxidative stress, inflammation, and neuronal cell apoptosis. During ischemic conditions, T-type calcium channel channels contribute to increase in intracellular calcium ions in both neurons and glial cells therefore, the current study hypothesizes the antagonism of these channels using ML218, a novel specific T-Type inhibitor in experimental model of cerebral ischemia-reperfusion (CI/R) brain injury. CI/R injury was induced in Swiss Albino mice by occlusion of common carotid arteries followed by reperfusion. Animals were assessed for learning and memory (MWM), motor coordination (Rota rod), neurological function (neurological deficit score), cerebral infarction, edema, and histopathological alterations. Biochemical assessments were made for calcium binding proteins (Calmodulin- CaM, calcium/calmodulin-dependent protein kinase II-CaMKII, S100B), oxidative stress (4-hydroxy 2-nonenal-4-HNE, glutathione-GSH, inflammation (nuclear factor kappa-light-chain-enhancer of activated B-p65-NF-kB, tumor necrosis factor-TNF-α, interleukin-IL-10) inducible nitric oxide synthase (iNOS) levels, and acetylcholinesterase activity (AChE) in brain supernatants. Furthermore, serum levels of NF-kB, iNOS, and S100B were also assessed. CI/R animals showed impairment in learning, memory, motor coordination, and neurological function along with increase in cerebral infarction, edema, and histopathological alterations. Furthermore, increase in brain calcium binding proteins, oxidative stress, inflammation, and AChE activity along with serum NF-kB, iNOS, and S100B levels were recorded in CI/R animals. Administration of ML218 (5 mg/kg and 10 mg/kg; i.p.) was observed to recuperate CI/R induced impairments in behavioral, biochemical, and histopathological analysis. Hence, it may be concluded that ML218 mediates neuroprotection during CI/R via decreasing brain and serum calcium binding proteins, inflammation, iNOS, and oxidative stress markers.

Dichloroacetate attenuates brain injury through inhibiting neuroinflammation and mitochondrial fission in a rat model of sepsis-associated encephalopathy

Sepsis-associated encephalopathy (SAE) is a severe complication of sepsis, characterized by neuroinflammation, mitochondrial dysfunction, and oxidative stress, leading to cognitive decline and high mortality. The effectiveness of dichloroacetate (DCA) in modulating mitochondrial function provides a novel therapeutic strategy for SAE. In this study, we evaluated the neuroprotective effects of DCA in a rat model of SAE induced by cecal ligation and puncture (CLP). Rats treated with DCA exhibited significant improvements in neurological function and survival, as evidenced by less neuron loss from histopathologic analysis, restored neurologic deficit scores, improved Y-maze alternation percentages, and enhanced recognition index performance. Biochemical analyses showed that DCA administration at 25 mg/kg and 100 mg/kg reduced astrocyte and microglial activation, indicating reduced neuroinflammation. Furthermore, DCA simultaneously reduced the production of circulating and cerebral inflammatory cytokines (including TNF-α, IL-1β, and IL-10), concomitant with mitigating oxidative stress through down-regulating expression of 8-Hydroxy-2'-deoxyguanosine (8-OHdG) and reactive oxygen species (ROS) in the brain. Mechanistically, DCA modulated mitochondrial dynamics by suppressing Drp1 and pDrp1 expression, which are indicators of mitochondrial fission. This was corroborated by transmission electron microscopy, quantification of mitochondrial area, and Western blot analyses. Furthermore, DCA treatment improved ATP levels, mitochondrial complex I activity, and NAD+/NADH ratio, indicating a significant attenuation of brain mitochondrial dysfunction. In conclusion, our findings suggest that DCA confers neuroprotection in SAE by curtailing neuroinflammation and mitochondrial fission, outlining a promising therapeutic strategy for treating SAE in critically ill patients.

Endogenous orexin and hyperacute autonomic responses after resuscitation in a preclinical model of cardiac arrest

Objectives

The study of autonomic responses to cardiac arrest (CA) resuscitation deserves attention due to the impact of autonomic function on survival and arousal. Orexins are known to modulate autonomic function, but the role of endogenous orexin in hyperacute recovery of autonomic function post-resuscitation is not well understood. We hypothesized that endogenous orexin facilitates hyperacute cardiovascular sympathetic activity post-resuscitation, and this response could be attenuated by suvorexant, a dual orexin receptor antagonist.

Methods

A well-established 7-min asphyxial CA rat model was studied. Heart rate (HR) and blood pressure were monitored from baseline to 90-min post-resuscitation. Autonomic function was evaluated by spectral analysis of HR variability, whereby the ratio of low- and high-frequency components (LF/HF ratio) represents the balance between sympathetic/parasympathetic activities. Plasma orexin-A levels and orexin receptors immunoreactivity in the rostral ventrolateral medulla (RVLM), the key central region for regulating sympathetic output, were measured post-resuscitation. Neurological outcome was assessed via neurologic-deficit score at 4-h post-resuscitation.

Key results

A significant increase in HR was found over 25-40 min post-resuscitation (p < 0.01 vs. baseline), which was attenuated by suvorexant significantly (p < 0.05). Increased HR (from 15-to 25-min post-resuscitation) was correlated with better neurological outcomes (rs = 0.827, p = 0.005). There was no evident increase in mean arterial pressure over 25-40 min post-resuscitation, while systolic pressure was reduced greatly by suvorexant (p < 0.05). The LF/HF ratio was higher in animals with favorable outcomes than in animals injected with suvorexant over 30-40 min post-resuscitation (p < 0.05). Plasma orexin-A levels elevated at 15-min and peaked at 30-min post-resuscitation (p < 0.01 vs. baseline). Activated orexin receptors-immunoreactive neurons were found co-stained with tyrosine hydroxylase-immunopositive cells in the RVLM at 2-h post-resuscitation.

Conclusion

Together, increased HR and elevated LF/HF ratio indicative of sympathetic arousal during a critical window (25-40 min) post-resuscitation are observed in animals with favorable outcomes. The orexin system appears to facilitate this hyperacute autonomic response post-CA.

Neuroprotective effect of autologous mitochondrial transplantation against global ischemia/reperfusion injury in a rat model of cardiac arrest

BACKGROUND

Mitochondria have emerged as a promising target for ischemic disease. A previous study reported the application of mitochondrial transplantation in focal cerebral ischemia/reperfusion injury, but it is unclear whether exogenous mitochondrial transplantation could be a therapeutic strategy for global ischemia/reperfusion injury induced by cardiac arrest.

METHODS

We hypothesized that transplantation of autologous mitochondria would rescue hippocampal cells and alleviate neurological impairment after cardiac arrest. In this study, we employed a rat cardiac arrest-global cerebral ischemia injury model (CA-GCII) and transplanted isolated mitochondria intravenously. Behavior test was applied to assess neurological deficit. Apoptosis and mitochondria permeability transition pore opening in hippocampus was determined using immunoblotting and swelling assay, respectively.

RESULTS

Transplanted mitochondria distributed throughout hippocampal cells and reduced oxidative stress. An improved neurological outcome was observed in rats receiving autologous mitochondria. In the hippocampus, mitophagy was enhanced while cell apoptosis was induced by ischemia/reperfusion insult was downregulated by mitochondrial transplantation. Mitochondrial permeability transition pore (MPTP) opening in surviving hippocampal cells was also suppressed.

CONCLUSIONS

These results indicated that transplantation of autologous mitochondria rescued hippocampal cells from ischemia/reperfusion injury and ameliorated neurological impairment caused by cardiac arrest.

Quercetin Protects Against Global Cerebral ischemia‒reperfusion Injury by Inhibiting Microglial Activation and Polarization

Background

This study aims to investigate the protective effect of quercetin against global cerebral ischemia‒reperfusion (GCI/R) injury in rats and elucidate the underlying mechanism.

Methods

A GCI/R injury rat model was established using a four-vessel occlusion (4-VO) method. An oxygen-glucose deprivation/reoxygenation (OGD/R) injury model was induced in BV2 cells. The extent of injury was assessed by evaluating neurological deficit scores (NDS) and brain water content and conducting behavioral tests. Pathomorphological changes in the prefrontal cortex were examined. Additionally, the study measured the levels of inflammatory cytokines, the degree of microglial activation and polarization, and the protein expression of Toll-like receptor 4 (TLR4) and TIR-domain-containing adaptor inducing interferon-β (TRIF).

Results

Quercetin pretreatment significantly ameliorated neurological impairment, improved learning and memory abilities, and reduced anxiety in rats subjected to GCI/R injury. Furthermore, quercetin administration effectively mitigated neuronal injury and brain edema. Notably, it suppressed microglial activation and hindered polarization toward the M1 phenotype. Simultaneously, quercetin downregulated the expression of TLR4 and TRIF proteins and attenuated the release of IL-1β and TNF-α.

Conclusion

This study highlights the novel therapeutic potential of quercetin in alleviating GCI/R injury. Quercetin demonstrates its neuroprotective effects by inhibiting neuroinflammation and microglial activation while impeding their transformation into the M1 phenotype through modulation of the TLR4/TRIF pathway.

BAICALEIN RELIEVES BRAIN INJURY VIA INHIBITING FERROPTOSIS AND ENDOPLASMIC RETICULUM STRESS IN A RAT MODEL OF CARDIAC ARREST

ABSTRACT

Background: Cardiac arrest (CA) is one of the leading causes of death worldwide. Endoplasmic reticulum (ER) stress and ferroptosis are proven pathological mechanisms implicated in neuronal damage. Baicalein, a ferroptosis Inhibitor, improved outcomes after traumatic brain injury. We aimed to explore the effects of baicalein on brain injury via ferroptosis and ER stress in a rat model of CA.Methods: Cardiac arrest models were established in Sprague-Dawley (SD) rats. The sham group (n = 6) was untreated with inducing ventricular fibrillation to cardiac arrest and cardiopulmonary resuscitation (CPR). Survival rats were randomly divided into five groups (n = 6). Ferroptosis inhibitor and ER stress agonist were administered separately and together in three groups. There was no drug intervention in the remaining group. The neurological deficit scores were recorded. Characteristics of ferroptosis were observed. And the associated protein of ferroptosis and ER stress were determined by Western blot. Cerebral ROS production was measured by using 2',7'-dichlorofluorescein diacetate as the oxidative fluorescent probe. Results: Baicalein treatment improved neurological outcomes and decreased neurocyte injuries compared with CPR group. The changes of ferroptosis, more specifically, iron content, glutathione peroxidase 4 (GPX4), reactive oxygen species (ROS), arachidonate 15-lipoxygenase (ALOX15) and mitochondrial characteristics, were observed in brain tissue after ROSC. ALOX15 was lower in baicalein group than in CPR group. The morphology and structure of mitochondria in baicalein group were better than in CPR group. The ER stress markers, glucose-regulated protein 78, activating Transcription Factor 4 and C/EBP homologous protein was lower in baicalein group compared with CPR group. ROS in tunicamycin group was higher than in CPR group. And ROS in baicalein +tunicamycin group was lower than in tunicamycin group. Conclusion: Ferroptosis and ER stress are both involved in brain injury after ROSC. Baicalein alleviates brain injury via suppressing the ferroptosis and ER stress, and reduces ROS partly through inhibiting ER stress. Baicalein is a potential drug to relieve brain injury after ROSC.

Rat model of asphyxia-induced cardiac arrest and resuscitation

Neurologic injury after cardiopulmonary resuscitation is the main cause of the low survival rate and poor quality of life among patients who have experienced cardiac arrest. In the United States, as the American Heart Association reported, emergency medical services respond to more than 347,000 adults and more than 7,000 children with out-of-hospital cardiac arrest each year. In-hospital cardiac arrest is estimated to occur in 9.7 per 1,000 adult cardiac arrests and 2.7 pediatric events per 1,000 hospitalizations. Yet the pathophysiological mechanisms of this injury remain unclear. Experimental animal models are valuable for exploring the etiologies and mechanisms of diseases and their interventions. In this review, we summarize how to establish a standardized rat model of asphyxia-induced cardiac arrest. There are four key focal areas: (1) selection of animal species; (2) factors to consider during modeling; (3) intervention management after return of spontaneous circulation; and (4) evaluation of neurologic function. The aim was to simplify a complex animal model, toward clarifying cardiac arrest pathophysiological processes. It also aimed to help standardize model establishment, toward facilitating experiment homogenization, convenient interexperimental comparisons, and translation of experimental results to clinical application.

Establishment of a nonshockable rhythm cardiac arrest model caused by asphyxia

OBJECTIVE

Cardiac arrest (CA) is caused by a nonshockable rhythm with a low success rate of return of spontaneous circulation (ROSC) and a poor prognosis. This study intended to establish a nonshockable rhythm CA model caused by asphyxia.

MATERIALS AND METHODS

Healthy adult male Wistar rats were injected with vecuronium bromide to induce CA. After the CA duration reached the target time point, cardiopulmonary resuscitation was performed. The survival status and neurological and cardiac function were evaluated after ROSC. Brain histopathology, including hematoxylin staining, Nissl staining and Terminal dUTP nick-end labeling (TUNEL) staining, was performed to evaluate the surviving cells and apoptotic cells. Apoptosis-related proteins after ROSC for 72 h were analyzed by western blot.

RESULTS

CA was successfully induced in all animals. The time for the three groups of animals to PEA was 320 ± 22 s in the CA-8 group, 322 ± 28 s in the CA-12 group and 320 ± 18 s in the CA-15 group. The time to asystole was 436 ± 54 s in the CA-8 group, 438 ± 62 s in the CA-12 group and 433 ± 56 s in the CA-15 group. The NDS of rats in the CA group was significantly decreased after ROSC for 24 h. The NDS in the CA-15 group was 5-16 points, while it was 58-67 points and 15-43 points in the CA-8 and CA-12 groups, respectively. The cardiac function of animals in the CA group was impaired after ROSC, and the ejection fraction, fractional shortening, stroke volume and cardiac output, were all significantly decreased. Brain histopathology showed that the number of surviving neurons was decreased, and the number of apoptotic cells was increased in CA group, the longer the CA duration, the more apoptotic cells increased. The expression of the proapoptotic protein Bax and the apoptotic executive protein caspase3 in the hippocampus of CA rats was significantly increased, while the expression of the antiapoptotic protein Bcl-2 was significantly reduced.

CONCLUSIONS

The use of vecuronium can successfully induce CA caused by nonshockable rhythm in rats, which will help to further study the pathophysiological changes after CA by nonshockable rhythm.

Time-Frequency Analysis of Somatosensory Evoked High-Frequency (600 Hz) Oscillations as an Early Indicator of Arousal Recovery after Hypoxic-Ischemic Brain Injury

Cardiac arrest (CA) remains the leading cause of coma, and early arousal recovery indicators are needed to allocate critical care resources properly. High-frequency oscillations (HFOs) of somatosensory evoked potentials (SSEPs) have been shown to indicate responsive wakefulness days following CA. Nonetheless, their potential in the acute recovery phase, where the injury is reversible, has not been tested. We hypothesize that time-frequency (TF) analysis of HFOs can determine arousal recovery in the acute recovery phase. To test our hypothesis, eleven adult male Wistar rats were subjected to asphyxial CA (five with 3-min mild and six with 7-min moderate to severe CA) and SSEPs were recorded for 60 min post-resuscitation. Arousal level was quantified by the neurological deficit scale (NDS) at 4 h. Our results demonstrated that continuous wavelet transform (CWT) of SSEPs localizes HFOs in the TF domain under baseline conditions. The energy dispersed immediately after injury and gradually recovered. We proposed a novel TF-domain measure of HFO: the total power in the normal time-frequency space (NTFS) of HFO. We found that the NTFS power significantly separated the favorable and unfavorable outcome groups. We conclude that the NTFS power of HFOs provides earlier and objective determination of arousal recovery after CA.

Glibenclamide Directly Prevents Neuroinflammation by Targeting SUR1-TRPM4-Mediated NLRP3 Inflammasome Activation In Microglia

Glibenclamide (GLB) reduces brain edema and improves neurological outcome in animal experiments and preliminary clinical studies. Recent studies also suggested a strong anti-inflammatory effect of GLB, via inhibiting nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome activation. However, it remains unknown whether the anti-inflammatory effect of GLB is independent of its role in preventing brain edema, and how GLB inhibits the NLRP3 inflammasome is not fully understood. Sprague-Dawley male rats underwent 10-min asphyxial cardiac arrest and cardiopulmonary resuscitation or sham-operation. The Trpm4 siRNA and GLB were injected to block sulfonylurea receptor 1-transient receptor potential M4 (SUR1-TRPM4) channel in rats. Western blotting, quantitative real-time polymerase chain reaction, behavioral analysis, and histological examination were used to evaluate the role of GLB in preventing NLRP3-mediated neuroinflammation through inhibiting SUR1-TRPM4, and corresponding neuroprotective effect. To further explore the underlying mechanism, BV2 cells were subjected to lipopolysaccharides, or oxygen-glucose deprivation/reperfusion. Here, in rat model of cardiac arrest with brain edema combined with neuroinflammation, GLB significantly alleviated neurocognitive deficit and neuropathological damage, via the inhibition of microglial NLRP3 inflammasome activation by blocking SUR1-TRPM4. Of note, the above effects of GLB could be achieved by knockdown of Trpm4. In vitro under circumstance of eliminating distractions from brain edema, SUR1-TRPM4 and NLRP3 inflammasome were also activated in BV2 cells subjected to lipopolysaccharides, or oxygen-glucose deprivation/reperfusion, which could be blocked by GLB or 9-phenanthrol, a TRPM4 inhibitor. Importantly, activation of SUR1-TRPM4 in BV2 cells required the P2X7 receptor-mediated Ca2+ influx, which in turn magnified the K+ efflux via the Na+ influx-driven opening of K+ channels, leading to the NLRP3 inflammasome activation. These findings suggest that GLB has a direct anti-inflammatory neuroprotective effect independent of its role in preventing brain edema, through inhibition of SUR1-TRPM4 which amplifies K+ efflux and promotes NLRP3 inflammasome activation.

p38 MAPK Endogenous Inhibition Improves Neurological Deficits in Global Cerebral Ischemia/Reperfusion Mice

Cerebral ischemia/reperfusion (I/R) injury is a complex pathophysiological process that can lead to neurological function damage and the formation of cerebral infarction. The p38 MAPK pathway has attracted considerable attention in cerebral I/R injury (IRI), but little research has been carried out on its direct role in vivo. In this study, to observe the effects of p38 MAPK endogenous inhibition on cerebral IRI, p38 heterozygous knockdown (p38^KI/+) mice were used. We hypothesized that p38 signaling might be involved in I/R injury and neurological damage reduction and that neurological behavioral deficits improve when p38 MAPK is inhibited. First, we examined the neurological damage and neurological behavioral deficit effects of I/R injury in WT mice. Cerebral I/R injury was induced by the bilateral common carotid artery occlusion (BCCAO) method. The cerebral infarction area and volume were assessed and analyzed by 2,3,5-triphenyltetrazolium chloride (TTC) staining. p38 MAPK and caspase-3 were detected by western blotting. Neuronal apoptosis was measured using TUNEL staining. Neurological deficits were detected by behavioral testing. Furthermore, to assess whether these neuroprotective effects occurred when p38 MAPK was inhibited, p38 heterozygous knockdown (p38^KI/+) mice were used. We found that p38 MAPK endogenous inhibition rescued hippocampal cell apoptosis, reduced ischemic penumbra, and improved neurological behavioral deficits. These findings showed that p38 MAPK endogenous inhibition had a neuroprotective effect on IRI and that p38 MAPK may be a potential therapeutic target for cerebral IRI.

Pomelo Peel Essential Oil Ameliorates Cerebral Ischemia-Reperfusion Injury through Regulating Redox Homeostasis in Rats and SH-SY5Y Cells

Background

In cardiac accident/cardiopulmonary resuscitation (CA/CPR) rat model, oxidative stress occurs during cerebral ischemia/reperfusion injury (CIRI), and antioxidative treatment has a neuroprotective effect. The antioxidant capabilities of pomelo peel essential oil (PPEO) have mostly been investigated in vitro, with little convincing data in vivo, particularly whether PPEO has a neuroprotective role against CIRI.

Methods

In this investigation, a CA/CPR SD rat model and an oxygen-glucose deprivation/reperfusion (OGD/R) SH-SY5Y cell model were used to imitate the CIRI, and the neuroprotective role of PPEO was discovered in both. The morphological changes of neurons after PPEO treatment were observed using Nissl staining and transmission electron microscopy, while biochemical markers such as MDA, GSH, and Fe²⁺ were evaluated. Furthermore, western blot, immunofluorescence, and immunohistochemistry were used to examine the proteins GPX4, SLC7A11, ACSL4, and Nrf2.

Results

Significant morphological alterations were identified during the pathological progression of CIRI. The neurologic deficit scores improved after PPEO therapy, and the expression of GPX4 and SLC7A11 increased, while the levels of intracellular Fe²⁺, ROS, and ACSL4 declined. PPEO also prevented CIRI caused by erastin (a specific inhibitor of SLC7A11) or RSL3 (inhibitor of GPX4). Furthermore, PPEO-induced increases in SLC7A11 and GPX4 may be related to Nrf2 translocation to the nucleus.

Conclusions

In vitro and in vivo, we verified and investigated the neuroprotective effects of PPEO on CIRI. The underlying process may be connected to redox homeostasis regulation, which enhances antioxidative capacity through upmodulation of SLC7A11 and GPX4. It implies that PPEO will be considered as a source of potential adjuvant therapeutic agents for improving CIRI outcomes.

The Effect of Mild Hypothermia on Nogo-A and Neurological Function in the Brain after Cardiopulmonary Resuscitation in Rats

ObjectiveWe investigated the dynamic changes of Nogo-A protein in brain and the effects of mild therapeutic hypothermia (MTH) on its expression after cardiopulmonary resuscitation (CPR). Methods: Western-blotting and neurological scoring of 45 rats subjected to cardiac arrest and CPR with and without MTR were performed to investigate the changes in the expression of Nogo-A protein in the hippocampus and cortex over a period of time ranging from 6 h to 72 h after restoration of spontaneous circulation (ROSC). Results: Nogo-A expression levels were increased at 6 h after CPR in the hippocampus and cortex, peaked at 24 h in the cortex, and at 48 h in the hippocampus. The expression of Nogo-A in the MTR group was significantly lower at 12 h (p < 0.05) compared to those with no MTR after ROSC. Conclusions: MTR blunts the expression of Nogo-A protein in the hippocampus and cortex after cardiac arrest and resuscitation, and MTR may provide cerebral protection after ischemia.

Early Thalamocortical Reperfusion Leads to Neurologic Recovery in a Rodent Cardiac Arrest Model

BACKGROUND

Cerebral blood flow (CBF) plays an important role in neurological recovery after cardiac arrest (CA) resuscitation. However, the variations of CBF recovery in distinct brain regions and its correlation with neurologic recovery after return of spontaneous circulation (ROSC) have not been characterized. This study aimed to investigate the characteristics of regional cerebral reperfusion following resuscitation in predicting neurological recovery.

METHODS

Twelve adult male Wistar rats were studied, ten resuscitated from 7-min asphyxial CA and two uninjured rats, which were designated as healthy controls (HCs). Dynamic changes in CBF in the cerebral cortex, hippocampus, thalamus, brainstem, and cerebellum were assessed by pseudocontinuous arterial spin labeling magnetic resonance imaging, starting at 60 min after ROSC to 156 min (or time to spontaneous arousal). Neurologic outcomes were evaluated by the neurologic deficit scale at 24 h post-ROSC in a blinded manner. Correlations between regional CBF (rCBF) and neurological recovery were undertaken.

RESULTS

All post-CA animals were found to be nonresponsive during the 60-156 min post ROSC, with reductions in rCBF by 24-42% compared with HC. Analyses of rCBF during the post-ROSC time window from 60 to 156 min showed the rCBF recovery of hippocampus and thalamus were positively associated with better neurological outcomes (rs = 0.82, p = 0.004 and rs = 0.73, p < 0.001, respectively). During 96 min before arousal, thalamic and cortical rCBF exhibited positive correlations with neurological recovery (rs = 0.80, p < 0.001 and rs = 0.65, p < 0.001, respectively); for predicting a favorable neurological outcome, the thalamic rCBF threshold was above 50.84 ml/100 g/min (34% of HC) (area under the curve of 0.96), whereas the cortical rCBF threshold was above 60.43 ml/100 g/min (38% of HC) (area under the curve of 0.88).

CONCLUSIONS

Early magnetic resonance imaging analyses showed early rCBF recovery in thalamus, hippocampus, and cortex post ROSC was positively correlated with neurological outcomes at 24 h. Our findings suggest new translational insights into the regional reperfusion and the time window that may be critical in neurological recovery and warrant further validation.

Systemic administration of dendrimer N-acetyl cysteine improves outcomes and survival following cardiac arrest

Cardiac arrest (CA), the sudden cessation of effective cardiac pumping function, is still a major clinical problem with a high rate of early and long-term mortality. Post-cardiac arrest syndrome (PCAS) may be related to an early systemic inflammatory response leading to exaggerated and sustained neuroinflammation. Therefore, early intervention with targeted drug delivery to attenuate neuroinflammation may greatly improve therapeutic outcomes. Using a clinically relevant asphyxia CA model, we demonstrate that a single (i.p.) dose of dendrimer-N-acetylcysteine conjugate (D-NAC), can target "activated" microglial cells following CA, leading to an improvement in post-CA survival rate compared to saline (86% vs. 45%). D-NAC treatment also significantly improved gross neurological score within 4 h of treatment (p < 0.05) and continued to show improvement at 48 h (p < 0.05). Specifically, there was a substantial impairment in motor responses after CA, which was subsequently improved with D-NAC treatment (p < 0.05). D-NAC also mitigated hippocampal cell density loss seen post-CA in the CA1 and CA3 subregions (p < 0.001). These results demonstrate that early therapeutic intervention even with a single D-NAC bolus results in a robust sustainable improvement in long-term survival, short-term motor deficits, and neurological recovery. Our current work lays the groundwork for a clinically relevant therapeutic approach to treating post-CA syndrome.

Pomelo peel oil suppresses TNF-α-induced necroptosis and cerebral ischaemia-reperfusion injury in a rat model of cardiac arrest

CONTEXT

Pomelo peel oil (PPO) [Citrus maxima (Burm.) Merr. (Rutaceae)] is reported to possess antioxidant and antimelanogenic activities.

OBJECTIVE

To investigate the effect of PPO [Citrus maxima (Burm.) Merr. cv. Shatian Yu] on tumour necrosis factor-α (TNF-α)-induced necroptosis in cerebral ischaemia-reperfusion injury (CIRI) after cardiac arrest (CA).

MATERIALS AND METHODS

Male Sprague Dawley rats were randomly assigned to six groups: sham group, PP0-L (10 mg/kg), PPO-M (20 mg/kg), PPO-H (40 mg/kg) and two control groups (CA, 0.9% saline; Gly, 10% glycerol). All drugs were administered intravenously to the CA/CPR rats within 10 min after return of spontaneous circulation (ROSC). After 24 h, rats were assessed for neuronal injury via the neurological deficit score (NDS), cerebral cortex staining and transmission electron microscopy (TEM) and expression levels of TNF-α and necroptosis-related proteins by immunoreactivity staining and western blotting.

RESULTS

Compared to those in the sham group (survival rate, 100% and NDS, 80), the survival rate and NDS were significantly reduced in the model groups (CA, 56.25%, 70; Gly, 62.5%, 71; PPO-L, 75%, 72; PPO-M, 87.5%, 75; PPO-H, 81.25%, 74). In the PPO-M group, Nissl bodies were significantly increased (43.67 ± 1.906 vs. 17 ± 1.732), the incidence of pathomorphological injury was lower and the necroptosis markers (TNF-α, RIPK1, RIPK3, p-MLKL/MLKL) expression was downregulated compared to those in the CA group (p < 0.05).

DISCUSSION AND CONCLUSIONS

The neuroprotective effects of PPO in the CA rats suggested that PPO possibility as a health product enhances the resistance ability against brain injury for humans.

Remote Ischemic Postconditioning Inhibited Mitophagy to Achieve Neuroprotective Effects in the Rat Model of Cardiac Arrest

Remote ischemic postconditioning (RI-postC) is an effective measure to improve nerve function after cardiac arrest. However, the brain protective mechanism of RI-postC has not been fully elucidated, and whether it is related to mitophagy is unclear. In this study, we used the rat model of cardiac arrest to study the effect of RI-postC on mitophagy and explore its possible signaling pathways. Rats were randomly divided into Sham group, CA/CPR group, Mdivi-1 group and RI-postC group. The animal model of cardiac arrest was established by asphyxia. RI-postC was performed by clamping and loosening the left femoral artery. Mdivi-1 was treated with a single intravenous injection. Levels of TOMM20, TIM23, Mfn1, PINK1 and parkin were detected by western blots. Mitochondrial membrane potential was measured by flow cytometry. Real-time PCR was used to detect relative mitochondrial DNA levels. The apoptosis of hippocampal neurons was detected by flow and TUNEL. In addition, Histopathological tests were performed. The results showed that RI-postC was similar to the mitophagy inhibitor Mdivi-1, which could inhibit the decrease of mitophagy-related protein level, improve mitochondrial membrane potential and up-regulate the ratio of mt-Atp6/Rpl13 after cardiopulmonary resuscitation (CPR). Furthermore, RI-postC could also reduce the rate of hippocampal nerve apoptosis and the damage of hippocampal neurons after CPR. Moreover, RI-postC and Mdivi-1 could reduce the protein levels of PINK1 and parkin in mitochondria after CPR, while increasing PINK1 levels in the cytoplasm. These findings suggested that RI-postC could inhibit the overactivation mitophagy through the PINK1/parkin signaling pathway, thus providing neuroprotective effects.

Intranasal Orexin After Cardiac Arrest Leads to Increased Electroencephalographic Gamma Activity and Enhanced Neurologic Recovery in Rats

Objectives

Prolonged cardiac arrest is known to cause global ischemic brain injury and functional impairment. Upon resuscitation, electroencephalographic recordings of brain activity begin to resume and can potentially be used to monitor neurologic recovery. We have previously shown that intrathecal orexin shows promise as a restorative drug and arousal agent in rodents. Our goal is to determine the electrophysiology effects of orexin in a rodent model of asphyxial cardiac arrest, focusing on the electroencephalographic activity in the gamma and super-gamma bands (indicative of return of higher brain function).

Design

Experimental animal study.

Setting

University-based animal research laboratory.

Subjects

Adult male Wistar rats.

Interventions

In an established model of asphyxial cardiac arrest (n = 24), we treated half of Wistar rats with orexin administered intranasally by atomizer 30 minutes post return of spontaneous circulation in one of two dose levels (10 and 50 µM); the rest were treated with saline as control. Continuous electroencephalographic recording was obtained and quantitatively analyzed for the gamma fraction. Gamma and high-frequency super-gamma band measures were compared against clinical recovery according to Neuro-Deficit Score.

Measurements and Main Results

Compared with the control cohort, the high-dose orexin cohort showed significantly better Neuro-Deficit Score 4 hours after return of spontaneous circulation (55.17 vs 47.58; p < 0.02) and significantly higher mean gamma fraction (0.251 vs 0.177; p < 0.02) in cerebral regions surveyed by rostral electrodes for the first 170 minutes after administration of orexin.

Conclusions

Our findings support early and continuous monitoring of electroencephalography-based gamma activity as a marker of better functional recovery after intranasal administration of orexin as measured by Neuro-Deficit Score in an established animal model of asphyxial cardiac arrest.

Effects of Different Degrees of Carotid Artery Stenosis on the Expression of XIAP and Smac in the Ischemic Penumbra of Rats with Cerebral Ischemia-Reperfusion

OBJECTIVE

To investigate the effects of different degrees of carotid artery stenosis (CAS) on the expression of XIAP and Smac in ischemic penumbra of rats with cerebral ischemia-reperfusion (I/R).

MATERIALS AND METHODS

Samples were collected at 12 h and 24 h after reperfusion, and then the treated groups were divided into the NC-12 group, NC-24 group, MIS-12 group, MIS-24 group, MOS-12 group, MOS-24 group, SES-12 group and SES-24 group. HE staining was used to observe the pathological changes of the brain tissue. TUNEL assay was used to detect the apoptosis in the ischemic penumbra. IHC and RT-qPCR were used to detect the expression of XIAP and Smac in the brain tissue.

RESULTS

By observing the pathological sections of brain tissue, the rats in MIS, MOS and SES groups showed loose brain tissue on the infarcted side and neuronal pyknosis in the ischemic penumbra. And with the aggravation and prolongation of the degree of stenosis, the degree of brain injury deepened. It was further found that the TUNEL positive rate was significantly increased in the ischemic penumbra in the SES and MOS groups compared with that in the normal control (NC) group. The results of IHC and RT-qPCR showed that the mRNA expression of XIAP and Smac in the ischemic penumbra was significantly up-regulated in the MIS, MOS and SES groups compared with that in the NC group.

CONCLUSIONS

CAS may activate XIAP/Smac signaling pathway to induce neuronal apoptosis and promote the injury in the ischemic penumbra caused by cerebral I/R.

Short-term dietary restriction ameliorates brain injury after cardiac arrest by modulation of mitochondrial biogenesis and energy metabolism in rats

Background

Dietary restriction (DR) is a well-known intervention that increases lifespan and resistance to multiple forms of acute stress, including ischemia reperfusion injury. However, the effect of DR on neurological injury after cardiac arrest (CA) remains unknown.

Methods

The effect of short-term DR (one week of 70% reduced daily diet) on neurological injury was investigated in rats using an asphyxial CA model. The survival curve was obtained using Kaplan-Meier survival analysis. Serum S-100β levels were detected by enzyme linked immunosorbent assay. Cellular apoptosis and neuronal damage were assessed by terminal deoxyribonucleotide transferase dUTP nick end labeling assay and Nissl staining. The oxidative stress was evaluated by immunohistochemical staining of 8-hydroxy-2'-deoxyguanosine (8-OHdG). Mitochondrial biogenesis was examined by electron microscopy and mitochondrial DNA copy number determination. The protein expression was detected by western blot. The reactive oxygen species (ROS) and metabolite levels were measured by corresponding test kits.

Results

Short-term DR significantly improved 3-day survival, neurologic deficit scores (NDS) and decreased serum S-100β levels after CA. Short-term DR also significantly attenuated cellular apoptosis, neuronal damage and oxidative stress in the brain after CA. In addition, short-term DR increased mitochondrial biogenesis as well as brain PGC-1α and SIRT1 protein expression after CA. Moreover, short-term DR increased adenosine triphosphate, β-hydroxybutyrate, acetyl-CoA levels and nicotinamide adenine dinucleotide (NAD⁺)/reduced form of NAD⁺ (NADH) ratios as well as decreased serum lactate levels.

Conclusions

Reduction of oxidative stress, upregulation of mitochondrial biogenesis and increase of ketone body metabolism may play a crucial role in preserving neuronal function after CA under short-term DR.

NLRP3 inflammasome-mediated microglial pyroptosis is critically involved in the development of post-cardiac arrest brain injury

Background

Brain injury is the leading cause of death and disability in survivors of cardiac arrest, where neuroinflammation is believed to play a pivotal role, but the underlying mechanism remains unclear. Pyroptosis is a pro-inflammatory form of programmed cell death that triggers inflammatory response upon infection or other stimuli. This study aims to understand the role of microglial pyroptosis in post-cardiac arrest brain injury.

Methods

Sprague-Dawley male rats underwent 10-min asphyxial cardiac arrest and cardiopulmonary resuscitation or sham-operation. Flow cytometry analysis, Western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), co-immunoprecipitation, and immunofluorescence were used to evaluate activated microglia and CD11b-positive leukocytes after cardiac arrest and assess inflammasome activation and pyroptosis of specific cellular populations. To further explore the underlying mechanism, MCC950 or Ac-YVAD-cmk was administered to block nod-like receptor family protein 3 (NLRP3) or caspase-1, respectively.

Results

Our results showed that, in a rat model, successful resuscitation from cardiac arrest resulted in microglial pyroptosis and consequential inflammatory infiltration which was mediated by the activation of NLRP3 inflammasome. Targeting NLRP3 and caspase-1, the executor of pyroptosis, with selective inhibitors MCC950 and Ac-YVAD-cmk treatment significantly prevented microglial pyroptosis, reduced infiltration of leukocytes, improved neurologic outcome, and alleviated neuro-pathological damages after cardiac arrest in modeling rats.

Conclusions

This study demonstrates that microglial pyroptosis mediated by NLRP3 inflammasome is critically involved in the pathogenesis of post-cardiac arrest brain injury and provides a new therapeutic strategy.

Electroencephalogram (EEG) Alpha Power as a Marker of Visuospatial Attention Orienting and Suppression in Normoxia and Hypoxia. An Exploratory Study

While electroencephalogram (EEG) alpha desynchronization has been related to anticipatory orienting of visuospatial attention, an increase in alpha power has been associated to its inhibition. A separate line of findings indicated that alpha is affected by a deficient oxygenation of the brain or hypoxia, although leaving unclear whether the latter increases or decreases alpha synchronization. Here, we carried out an exploratory study on these issues by monitoring attention alerting, orienting, and control networks functionality by means of EEG recorded both in normoxia and hypoxia in college students engaged in four attentional cue-target conditions induced by a redesigned Attention Network Test. Alpha power was computed through Fast Fourier Transform. Regardless of brain oxygenation condition, alpha desynchronization was the highest during exogenous, uncued orienting of spatial attention, the lowest during alerting but spatially unpredictable, cued exogenous orienting of attention, and of intermediate level during validly cued endogenous orienting of attention, no matter the motor response workload demanded by the latter, especially over the left hemisphere. Hypoxia induced an increase in alpha power over the right-sided occipital and parietal scalp areas independent of attention cueing and conflict conditions. All in all, these findings prove that attention orienting is undergirded by alpha desynchronization and that alpha right-sided synchronization in hypoxia might sub-serve either the effort to sustain attention over time or an overall suppression of attention networks functionality.

Bone marrow-derived mesenchymal stem cell transplantation attenuates overexpression of inflammatory mediators in rat brain after cardiopulmonary resuscitation

Emerging evidence suggests that bone marrow-derived mesenchymal stem cell transplantation improves neurological function after cardiac arrest and cardiopulmonary resuscitation; however, the precise mechanisms remain unclear. This study aimed to investigate the effect of bone marrow-derived mesenchymal stem cell treatment on expression profiles of multiple cytokines in the brain after cardiac arrest and cardiopulmonary resuscitation. Cardiac arrest was induced in rats by asphyxia and cardiopulmonary resuscitation was initiated 6 minutes after cardiac arrest. One hour after successful cardiopulmonary resuscitation, rats were injected with either phosphate-buffered saline (control) or 1 × 10⁶ bone marrow-derived mesenchymal stem cells via the tail vein. Serum S100B levels were measured by enzyme-linked immunosorbent assay and neurological deficit scores were evaluated to assess brain damage at 3 days after cardiopulmonary resuscitation. Serum S100B levels were remarkably decreased and neurological deficit scores were obviously improved in the mesenchymal stem cell group compared with the phosphate-buffered saline group. Brains were isolated from the rats and expression levels of 90 proteins were determined using a RayBio Rat Antibody Array, to investigate the cytokine profiles. Brain levels of the inflammatory mediators tumor necrosis factor-α, interferon-γ, macrophage inflammatory protein-1α, macrophage inflammatory protein-2, macrophage inflammatory protein-3α, macrophage-derived chemokine, and matrix metalloproteinase-2 were decreased ≥ 1.5-fold, while levels of the anti-inflammatory factor interleukin-10 were increased ≥ 1.5-fold in the mesenchymal stem cell group compared with the control group. Donor mesenchymal stem cells were detected by immunofluorescence to determine their distribution in the damaged brain, and were primarily observed in the cerebral cortex. These results indicate that bone marrow-derived mesenchymal stem cell transplantation attenuates brain damage induced by cardiac arrest and cardiopulmonary resuscitation, possibly via regulation of inflammatory mediators. This experimental protocol was approved by the Institutional Animal Care and Use Committee of Fujian Medical University, China in January 2016 (approval No. 2016079).

Anti‑Nogo‑A antibody promotes brain function recovery after cardiopulmonary resuscitation in rats by reducing apoptosis

Brain injury after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) is the main cause of neurological dysfunction and death in cardiac arrest. To assess the effect of Nogo-A antibody on brain function in rats following CPR and to explore the underlying mechanisms, CA/CPR (ventricular fibrillation) rats were divided into the CPR+Nogo-A, CPR+saline and sham groups. Hippocampal caspase-3 levels were detected by RT-PCR and immunoblotting. Next, Nogo-A, glucose regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), cysteinyl aspartate specific proteinase-12 (casapse-12), Bcl-2 and Bax protein levels in the hippocampus were detected by immunoblotting. Coronal brain sections were analyzed by TUNEL assay to detect apoptosis at 72 h, while Nissl staining and electron microscopy were performed to detect Nissl bodies and microstructure at 24 h, respectively. Finally, rats were assessed for neurologic deficits at various times. Nissl staining revealed morphological improvement after Nogo-A antibody treatment. Sub-organelle structure was preserved as assessed by electron microscopy in model animals post-antibody treatment; neurological function was improved as well (P<0.05), while the apoptosis index was decreased (26.2±9.85 vs. 46.6±12.95%; P<0.05). Hippocampal caspase-3 mRNA and protein, Nogo-A protein levels were significantly decreased after antibody treatment (P<0.05). Hippocampal Nogo-A expression was positively correlated with caspase-3 (Pearson's correlation; r=0.790, P=0.000). Hippocampal GRP78 and Bcl-2 protein levels were higher after antibody treatment than these levels noted in the model animals (P<0.05), while CHOP, caspase-12 and Bax levels were reduced (P<0.05). Nogo-A antibody ameliorates neurological function after restoration of spontaneous circulation (ROSC), possibly by suppressing apoptosis induced by endoplasmic reticulum stress.

Therapeutic hypothermia promotes cerebral blood flow recovery and brain homeostasis after resuscitation from cardiac arrest in a rat model

Laboratory and clinical studies have demonstrated that therapeutic hypothermia (TH), when applied as soon as possible after resuscitation from cardiac arrest (CA), results in better neurological outcome. This study tested the hypothesis that TH would promote cerebral blood flow (CBF) restoration and its maintenance after return of spontaneous circulation (ROSC) from CA. Twelve Wistar rats resuscitated from 7-min asphyxial CA were randomized into two groups: hypothermia group (7 H, n = 6), treated with mild TH (33-34℃) immediately after ROSC and normothermia group (7 N, n = 6,37.0 ± 0.5℃). Multiple parameters including mean arterial pressure, CBF, electroencephalogram (EEG) were recorded. The neurological outcomes were evaluated using electrophysiological (information quantity, IQ, of EEG) methods and a comprehensive behavior examination (neurological deficit score, NDS). TH consistently promoted better CBF restoration approaching the baseline levels in the 7 H group as compared with the 7 N group. CBF during the first 5-30 min post ROSC of the two groups was 7 H:90.5% ± 3.4% versus 7 N:76.7% ± 3.5% (P < 0.01). Subjects in the 7 H group showed significantly better IQ scores after ROSC and better NDS scores at 4 and 24 h. Early application of TH facilitates restoration of CBF back to baseline levels after CA, which in turn results in the restoration of brain electrical activity and improved neurological outcome.

Neuroprotective effects of irisin against cerebral ischemia/ reperfusion injury via Notch signaling pathway

Irisin, a 112-amino acid peptide induced with exercise in mice and human is thought to have correlation with the short-term outcomes of patients in ischemic stroke. In the present study, the neuroprotective effects of irisin were evaluated in vivo and in vitro and its underlying mechanism was also explored. The global cerebral ischemia/reperfusion (I/R) model was established by bilateral common carotid artery occlusion for 20 min and reperfusion for 24 h in mice and oxygen-glucose deprivation/reperfusion in HT22 cells. Neurological function was scored and then the mice were sacrificed. The brains were harvested for HE staining and detection of brain water content (BWC). The percentage of neuronal apoptosis was evaluated by TUNEL and flow cytometry analysis. The mRNA expression of TNF-α and IL-1β was detected by RT-PCR analysis. The Notch intracellular domain (NICD) was detected by double immunofluorescence staining and western blot, and the protein expression of Notch1 and Hes 1 was detected by western blot. It was observed that irisin could alleviate morphological damage and improve neurological function after global cerebral I/R injury in mice. The apoptosis of hippocampal neurons reduced in the presence of irisin in vivo and in vitro. Additionally irisin could downregulate the expression of IL-1β and TNF-α and upregulate the expression of NICD, Notch1 and Hes 1 in vitro and in vivo. After the application of γ-secretase inhibitor DAPT, all the morphological, neurological and biochemical changes were reversed. Taken together, these results suggest that irisin could regulate the Notch signaling pathway that leads to the alleviation of transient global cerebral I/R injury.

Hypothermic properties of dexmedetomidine provide neuroprotection in rats following cerebral ischemia-reperfusion injury

Dexmedetomidine (Dex) is a sedative and analgesic agent that is widely administered to patients admitted to the intensive care unit, and has been demonstrated to result in hypothermia. Many patients have been revealed to benefit from therapeutic hypothermia, which can mitigate cerebral ischemia/reperfusion (I/R) injury following successful cardiopulmonary resuscitation. However, studies investigating the efficacy of Dex in I/R treatment is lacking. The present study aimed to investigate the efficacy of Dex in mitigating neuronal damage, and to determine the possible mechanism of its effects in a rat model of cardiac arrest (CA). CA was induced in Sprague-Dawley rats by asphyxiation for 5 min. Following successful resuscitation, the surviving rats were randomly divided into two treatment groups; one group was intraperitoneally administered with Dex (D group), whereas the control group was treated with normal saline (N group). Critical parameters, including core temperature and blood pressure were monitored following return of spontaneous circulation (ROSC). Arterial blood samples were collected at 10 min after surgery (baseline) 30 and 120 min post-ROSC; and neurological deficit scores (NDS) of the rats were taken 12 or 24 h after ROSC prior to euthanasia. The hippocampal tissue was then removed for analysis by histology, electron microscopy and western blotting. Rats in the D group exhibited a lower core temperature and higher NDS scores compared with the N group (P<0.05). In addition, Dex injection resulted in reduced expression of apoptotic and autophagy-associated factors in the hippocampus (P<0.05). Dex treatment induced hypothermia and improved neurological function in rats after ROSC following resuscitation from CA by inhibiting neuronal apoptosis and reducing autophagy, which suggested that Dex may be a potential therapy option for patients with CA.

Surge of corticocardiac coupling in SHRSP rats exposed to forebrain cerebral ischemia

Sudden death is an important but underrecognized consequence of stroke. Acute stroke can disturb central control of autonomic function and result in cardiac dysfunction and sudden death. Previous study showed that bilateral common carotid artery ligation (BCCAL) in the spontaneously hypertensive stroke-prone rat strain (SHRSP) is a well-established model for forebrain ischemic sudden death. This study aims to investigate the temporal dynamic changes in electrical activities of the brain and heart and functional interactions between the two vital organs following forebrain ischemia. EEG and ECG signals were simultaneously collected from nine SHRSP and eight Wistar-Kyoto (WKY) rats. RR interval was analyzed to investigate the cardiac response to brain ischemia. EEG power and coherence (CCoh) analysis were conducted to study the cortical response. Corticocardiac coherence (CCCoh) and directional connectivity (CCCon) were analyzed to determine brain-heart connection. Heart rate variability (HRV) was analyzed to evaluate autonomic functionality. BCCAL resulted in 100% mortality in SHRSP within 14 h, whereas no mortality was observed in WKY rats. The functionality of both the brain and the heart were significantly altered in SHRSP compared with WKY rats after BCCAL. SHRSP, but not WKY rats, exhibited intermittent surge of CCCoh, which paralleled the elevated CCCon and reduced HRV, following the onset of ischemia until sudden death. Elevated brain-heart coupling invariably associated with the disruption of the autonomic nervous system and the risk of sudden death. This study may improve our understanding of the mechanism of forebrain ischemia-induced sudden death. NEW & NOTEWORTHY This study demonstrates a marked surge of corticocardiac coupling in rats dying from focal cerebral ischemia, consistent with our earlier data in rats exposed to fatal asphyxia. Since the bidirectional electrical signal coupling (corticocardiac coherence) and communication (corticocardiac connectivity) between the brain and the heart are only identified in dying animals, they could be used as potential biomarkers to predict the risk of sudden death.

Activation of Sigma-1 Receptor by Cutamesine Attenuates Neuronal Apoptosis by Inhibiting Endoplasmic Reticulum Stress and Mitochondrial Dysfunction in a Rat Model of Asphyxia Cardiac Arrest

BACKGROUND

Global cerebral ischemic/reperfusion (I/R) injury after cardiac arrest (CA) is a major cause of mortality and morbidity in survivors of resuscitation. We utilized a rat model of asphyxia CA to explore the functional effects and mechanisms of Sigma-1 receptor (Sig-1R) activation in cerebral protection using the Sig-1R agonist cutamesine (SA-4503).

METHODS

After resuscitation, the surviving rats were randomly divided into three groups (n = 18 each): the cardiopulmonary resuscitation (CPR) group (0.9% saline at 1 mL/kg); the SA4503 low-dose group (1 mg/kg SA4503); and the SA4503 high-dose group (2.5 mg/kg SA4503). The neurological deficit scores were recorded, and the cerebral cortex was harvested for western blotting. Mitochondrial transmembrane potential, adenosine triphosphate (ATP) concentrations, calcium homeostasis, and mitochondrial ultrastructure were also studied.

RESULTS

The SA4503 treatment groups exhibited improved neurological outcomes compared with the CPR group. The protein levels of caspase-3 and the endoplasmic reticulum stress markers C/EBP homologous protein and caspase-12 were lower in the SA4503 treatment groups compared with the CPR group. SA4503 treatment also normalized mitochondrial membrane potential, tissue ATP concentrations, intracellular Ca overload, and upregulated Sig-1R protein level compared with the CPR group. The SA4503 high dose treatment showed significant cerebral protective effects compared with the SA4503 low dose treatment. The therapeutic effect of SA4503 was dose-dependent.

CONCLUSIONS

CA downregulated Sig-1R protein expression. Activating Sig-1R using SA4503 protected against global cerebral I/R injury in a rat model of asphyxia CA by alleviating endoplasmic reticulum stress and mitochondrial dysfunction and eventually inhibiting neuronal apoptosis.

Intravenous Transplants of Human Adipose-Derived Stem Cell Protect the Rat Brain From Ischemia-Induced Damage

BACKGROUND

Survival following cardiac arrest (CA) and subsequent cardiopulmonary resuscitation (CPR), to a great extent, depends on brain damage. Adipose-derived stem cells (ADSCs), as a source of paracrine growth factors and the capacity of neural differentiation may reduce this brain damage.

OBJECTIVE

The purpose of this study is to evaluate the protection of ADSCs to brain damage following CPR.

METHODS

Rats were divided into 3 groups, sham, CA, and ADSCs group. Rats in sham group went through sham surgery. Rats in CA group went through CA, CPR, and injection PBS (phosphate buffer saline). Rats in ADSCs group went through CA, CPR, and intravenous injection of ADSCs. Rats in sham group were sacrificed immediately after operation. At 24, 72, and 168 hours after return of spontaneous circulation operation, rats in CA and ADSCs group were randomly selected and sacrificed. Brain damage was evaluated by using Neurological Deficit Scale (NDS) score, hippocampal pathology, serum level of S100β, and apoptosis ratio of hippocampal neurons. Protein of brain derived neurotrophic factor (BDNF) and IL-6 (interleukin-6) in the hippocampus were detected.

RESULTS

Compared with sham group, CA and ADSCs group showed a decrease in NDS score, an increased apoptosis ratio of hippocampal nerve cells, increased serum level of S100-β, and a significant increase in neuroprotective IL-6 and BDNF. In comparison to CA group, ADSCs group had a mild degree of brain damage and higher expression of IL-6 and BDNF.

CONCLUSIONS

In the acute stage of cerebral injury following CA, ADSCs might improve the prognosis of brain damage by stimulating the expression of neuroprotective IL-6 and BDNF.

Glibenclamide Prevents Water Diffusion Abnormality in the Brain After Cardiac Arrest in Rats

BACKGROUND

Glibenclamide (GBC) improves neurological outcome after cardiac arrest (CA) in rats. In this study, we sought to elucidate the mechanism responsible for the neuroprotective effects of GBC by using a high-field MRI system.

METHODS

Male Sprague-Dawley rats were subjected to 10-min asphyxial CA followed by cardiopulmonary resuscitation (CPR). Diffusion-weighted imaging (DWI) as well as conventional T2-weighted imaging was conducted prior to CA and at 24, 48, and 72 h after resuscitation. Afterward, histological examination was performed.

RESULTS

Twelve rats were randomized to receive GBC (n = 6) or vehicle (n = 6) at 15 min after return of spontaneous circulation, while four rats were set as sham control. Rats that underwent CA/CPR and received vehicle exhibited distinct neurological deficit, which was alleviated by GBC treatment. Marked water diffusion abnormality as demonstrated by hyperintense DWI in vulnerable regions of the brain was detected after CA/CPR, with the most prominent hyperintense DWI observed in the hippocampal CA1 region at 72 h. Consistently, histological examination revealed neuronal swelling, dendritic injury, and activation of astrocytes and microglia in the hippocampal CA1 region in vehicle-treated rats. Correlation analysis revealed that the ADC values in the hippocampus were significantly correlated with the histological findings (all p < 0.05).

CONCLUSION

These results suggest that the neuroprotective effects of GBC after CA was exerted, as least in part, through prevention of water diffusion abnormality, namely brain edema.

Metformin Improves Neurologic Outcome Via AMP-Activated Protein Kinase-Mediated Autophagy Activation in a Rat Model of Cardiac Arrest and Resuscitation

BACKGROUND

Sudden cardiac arrest (CA) often results in severe injury to the brain, and neuroprotection after CA has proved to be difficult to achieve. Herein, we sought to investigate the effects of metformin pretreatment on brain injury secondary to CA and cardiopulmonary resuscitation.

METHODS AND RESULTS

Rats were subjected to 9-minute asphyxial CA after receiving daily metformin treatment for 2 weeks. Survival rate, neurologic deficit scores, neuronal loss, AMP-activated protein kinase (AMPK), and autophagy activation were assessed at indicated time points within the first 7 days after return of spontaneous circulation. Our results showed that metformin pretreatment elevated the 7-day survival rate from 55% to 85% and significantly reduced neurologic deficit scores. Moreover, metformin ameliorated CA-induced neuronal degeneration and glial activation in the hippocampal CA1 region, which was accompanied by augmented AMPK phosphorylation and autophagy activation in affected neuronal tissue. Inhibition of AMPK or autophagy with pharmacological inhibitors abolished metformin-afforded neuroprotection, and augmented autophagy induction by metformin treatment appeared downstream of AMPK activation.

CONCLUSIONS

Taken together, our data demonstrate, for the first time, that metformin confers neuroprotection against ischemic brain injury after CA/cardiopulmonary resuscitation by augmenting AMPK-dependent autophagy activation.

An enhanced cerebral recovery index for coma prognostication following cardiac arrest

Prognostication of coma outcomes following cardiac arrest is both qualitative and poorly understood in current practice. Existing quantitative metrics are powerful, but lack rigorous approaches to classification. This is due, in part, to a lack of available data on the population of interest. In this paper we describe a novel retrospective data set of 167 cardiac arrest patients (spanning three institutions) who received electroencephalography (EEG) monitoring. We utilized a subset of the collected data to generate features that measured the connectivity, complexity and category of EEG activity. A subset of these features was included in a logistic regression model to estimate a dichotomized cerebral performance category score at discharge. We compared the predictive performance of our method against an established EEG-based alternative, the Cerebral Recovery Index (CRI) and show that our approach more reliably classifies patient outcomes, with an average increase in AUC of 0.27.

Dynamic Changes of Mitochondrial Fusion and Fission in Brain Injury after Cardiac Arrest in Rats

Mitochondria change their morphology dynamically by continual fusion and fission processes to fulfill their function. However, little is known about the effect of cardiac arrest on mitochondrial dynamics. This study aimed to investigate time-dependent change of the mitochondrial dynamics after brain ischemic injury in rats of cardiac arrest. After resuscitation, obvious neuronal injury, reduced adenosine triphosphate (ATP) levels, excessive reactive oxygen species (ROS) generation, decreased mitochondrial membrane potential (MMP), and increased release of mitochondrial cytochrome c were observed at 12 h and 24 h after cardiac arrest. Moreover, we found that elongation of mitochondria was observed at 4 h after cardiac arrest, whereas fragmented mitochondria were significantly increased, along with concomitant increase in the fission proteins Drp1 and Fis1 and a reduction in the fusion proteins Mfn1 and Mfn2 at 12 h and 24 h after cardiac arrest. Taken together, these findings suggest that imbalance in mitochondrial dynamics probably contributes to brain injury after cardiac arrest.

Effect of hypothermia on apoptosis in traumatic brain injury and hemorrhagic shock model

INTRODUCTION

The neuroprotective mechanisms of therapeutic hypothermia against trauma-related injury have not been fully understood yet. In this study, we aimed to investigate the effects of therapeutic hypothermia on biochemical and histopathological markers of apoptosis using Traumatic brain injury (TBI) and hemorrhagic shock (HS) model.

METHODS

A total of 50 male albino-wistar rats were divided into five groups: Group isolated TBI, Group NT (HT+HS+normothermia), Group MH (HT+HS+mild hypothermia), Group MoH (HT+HS+moderate hypothermia) and Group C (control). Neurological deficit scores were assessed at baseline and at 24h. The rats were, then, sacrificed to collect serum and brain tissue samples. Levels of Caspase-3,6,8, proteoglycan-4 (PG-4), malondialdehyde (MDA), and nitric oxide (NO) were measured in serum and brain tissue samples. Histopathological examination was performed in brain tissue.

RESULTS

There were significant differences in the serum levels of Caspase-3 between Group NT and Group C (p=0.018). The serum levels of Caspase-6 in Group NT (0.70±0.58) were lower than Group MH (1.39±0.28), although the difference was not statistically significant (p=0.068). There were significant differences in the brain tissue samples for Caspase-3 levels between Group NT and Group C (p=0.049). A significant difference in the Caspase-8 brain tissue levels was also observed between Group NT and Group C (p=0.022). Group NT had significantly higher scores of all the pathological variables (for edema p<0.017; for gliosis p<0.001; for congestion p<0.003, for hemorrhage p<0.011) than Group C.

CONCLUSION

Our study results suggest that hypothermia may exert its neuroprotective effects by reducing markers of apoptotic pathway, particularly Caspase-3 on TBI and HS.

The Molecular Mechanism and Neuroprotective Effect of Dihydrocapsaicin-Induced Mild Hypothermia After Cardiopulmonary Resuscitation in Rats

To investigate the molecular mechanism of dihydrocapsaicin (DHC)-induced mild hypothermia in rats, and to compare its protective effect on the central nervous system with that of a conventional method of inducing hypothermia, 24 healthy male Sprague Dawley rats were randomly divided into four groups based on the following conditions: control group, cardiopulmonary resuscitation (CPR) group, body surface cooling group, and DHC group. Tracheal clipping was used to mimic asphyxia arrest. Rats were assessed for their neurological deficit scores. After sacrifice, immunohistochemical staining was used to examine caspase-3 expression in the cerebral cortex and TRPV1 (transient receptor potential vanilloid subfamily, member 1) expression in the hypothalamus. Terminal TdT-mediated dUTP-biotin nick end labeling (TUNEL) staining was used to evaluate cell apoptosis in the cerebral cortex. Furthermore, intracellular Ca²⁺ concentration in the hypothalamus and arginine vasopressin (AVP) concentration in ventral septal tissues were also detected in these four groups. Results of our study showed that neurological deficit scores in the DHC group were significantly higher than those in the CPR and body surface cooling groups (p < 0.05). Caspase-3 expression in the cerebral cortex of control group rats was significantly lower than that in other three groups (p < 0.05). Hypothalamic TRPV1 expression, hypothalamic intracellular Ca²⁺ concentration, and AVP concentration in the ventral septum in the DHC group were significantly higher than that in the other three groups (p < 0.05). Within these three groups, there were significantly fewer apoptotic cells in the DHC and body surface cooling group rats than in the CPR group rats (p < 0.05). DHC has the neuroprotective effect. DHC induced mild hypothermia and reduces apoptosis through a mechanism whereby DHC activates TRPV1 on hypothalamic cells to cause a large Ca²⁺ influx, which alters corresponding physiological functions and causes the release of AVP to induce hypothermia.

Intranasal post-cardiac arrest treatment with orexin-A facilitates arousal from coma and ameliorates neuroinflammation

Cardiac arrest (CA) entails significant risks of coma resulting in poor neurological and behavioral outcomes after resuscitation. Significant subsequent morbidity and mortality in post-CA patients are largely due to the cerebral and cardiac dysfunction that accompanies prolonged whole-body ischemia post-CA syndrome (PCAS). PCAS results in strong inflammatory responses including neuroinflammation response leading to poor outcome. Currently, there are no proven neuroprotective therapies to improve post-CA outcomes apart from therapeutic hypothermia. Furthermore, there are no acceptable approaches to promote cortical or cognitive arousal following successful return of spontaneous circulation (ROSC). Hypothalamic orexinergic pathway is responsible for arousal and it is negatively affected by neuroinflammation. However, whether activation of the orexinergic pathway can curtail neuroinflammation is unknown. We hypothesize that targeting the orexinergic pathway via intranasal orexin-A (ORXA) treatment will enhance arousal from coma and decrease the production of proinflammatory cytokines resulting in improved functional outcome after resuscitation. We used a highly validated CA rat model to determine the effects of intranasal ORXA treatment 30-minute post resuscitation. At 4hrs post-CA, the mRNA levels of proinflammatory markers (IL1β, iNOS, TNF-α, GFAP, CD11b) and orexin receptors (ORX1R and ORX2R) were examined in different brain regions. CA dramatically increased proinflammatory markers in all brain regions particularly in the prefrontal cortex, hippocampus and hypothalamus. Post-CA intranasal ORXA treatment significantly ameliorated the CA-induced neuroinflammatory markers in the hypothalamus. ORXA administration increased production of orexin receptors (ORX1R and ORX2R) particularly in hypothalamus. In addition, ORXA also resulted in early arousal as measured by quantitative electroencephalogram (EEG) markers, and recovery of the associated behavioral neurologic deficit scale score (NDS). Our results indicate that intranasal delivery of ORXA post-CA has an anti-inflammatory effect and accelerates cortical EEG and behavioral recovery. Beneficial outcomes from intranasal ORXA treatment lay the groundwork for therapeutic clinical approach to treating post-CA coma.

Enhanced neuroprotective efficacy of bone marrow mesenchymal stem cells co-overexpressing BDNF and VEGF in a rat model of cardiac arrest-induced global cerebral ischemia

Cardiac arrest-induced global cerebral ischemia injury (CA-GCII) usually leads to a poor neurological outcome without an effective treatment. Bone marrow-derived mesenchymal stem cells (BMMSCs) may provide a potential cell-based therapy against neurologic disorders through induction of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF). To optimize the neuroprotective efficacy of BMMSCs further, in this study we have derived BMMSCs, which co-overexpress both BDNF and VEGF, and tested them for the treatment of CA-GCII in a rat model. Lentiviruses that express rat BDNF exon IV or VEGF-A were created using the bicistronic shuttle vectors of pLVX-IRES-ZsGreen1 and pLVX-IRES-tdTomato, respectively. BMMSCs that were co-transduced with the engineered lentiviruses with co-overexpression of both BDNF and VEGF along with corresponding fluorescent protein reporters were injected via jugular vein of rats that just recovered from a cardiac arrest. Animals were then scored for neurofunctional deficits and examined for brain pathology and gene expression relevant to the engraftment seven days after the treatments. We demonstrate that anchorage of lentiviral vector-transduced BMMSCs, which co-overexpressed both BDNF and VEGF in the hippocampus and temporal cortex along with significantly ameliorated brain pathology and improved neurofunctional performance in CA-GCII rats after transplantation. These findings provide a proof of concept for the further validation of engineered BMMSCs for the treatment of CA-GCII patients in clinical practice in the future.

Diazoxide Attenuates Postresuscitation Brain Injury in a Rat Model of Asphyxial Cardiac Arrest by Opening Mitochondrial ATP-Sensitive Potassium Channels

Objective. We investigated whether and how diazoxide can attenuate brain injury after cardiopulmonary resuscitation (CPR) by selective opening of mitochondrial ATP-sensitive potassium (mitoKATP) channels. Methods. Adult male Sprague-Dawley rats with induced cerebral ischemia (n = 10 per group) received an intraperitoneal injection of 0.1% dimethyl sulfoxide (1 mL; vehicle group), diazoxide (10 mg/kg; DZ group), or diazoxide (10 mg/kg) plus 5-hydroxydecanoate (5 mg/kg; DZ + 5-HD group) 30 min after CPR. The control group (sham group, n = 5) underwent sham operation, without cardiac arrest. Mitochondrial respiratory control rate (RCR) was determined. Brain cell apoptosis was assessed using TUNEL staining. Expression of Bcl-2, Bax, and protein kinase C epsilon (PKCε) in the cerebral cortex was determined by Western blotting and immunohistochemistry. Results. The neurological deficit scores (NDS) in the vehicle group decreased significantly at 24 h and 48 h after CPR. Diazoxide significantly improved NDS and mitochondrial RCR after CPR at both time points; 5-HD cotreatment abolished these effects. Diazoxide decreased TUNEL-positive cells following CPR, upregulated Bcl-2 and PKCε, downregulated Bax, and increased the Bcl-2/Bax ratio; 5-HD cotreatment reversed these effects. Conclusions. Diazoxide attenuates postresuscitation brain injury, protects mitochondrial function, inhibits brain cell apoptosis, and activates the PKC pathway by opening mitoKATP channels.

Carbon Monoxide Improves Neurologic Outcomes by Mitochondrial Biogenesis after Global Cerebral Ischemia Induced by Cardiac Arrest in Rats

Mitochondrial dysfunction contributes to brain injury following global cerebral ischemia after cardiac arrest. Carbon monoxide treatment has shown potent cytoprotective effects in ischemia/reperfusion injury. This study aimed to investigate the effects of carbon monoxide-releasing molecules on brain mitochondrial dysfunction and brain injury following resuscitation after cardiac arrest in rats. A rat model of cardiac arrest was established by asphyxia. The animals were randomly divided into the following 3 groups: cardiac arrest and resuscitation group, cardiac arrest and resuscitation plus carbon monoxide intervention group, and sham control group (no cardiac arrest). After the return of spontaneous circulation, neurologic deficit scores (NDS) and S-100B levels were significantly decreased at 24, 48, and 72 h, but carbon monoxide treatment improved the NDS and S-100B levels at 24 h and the 3-day survival rates of the rats. This treatment also decreased the number of damaged neurons in the hippocampus CA1 area and increased the brain mitochondrial activity. In addition, it increased mitochondrial biogenesis by increasing the expression of biogenesis factors including peroxisome proliferator-activated receptor-γ coactivator-1α, nuclear respiratory factor-1, nuclear respiratory factor-2 and mitochondrial transcription factor A. Thus, this study showed that carbon monoxide treatment alleviated brain injury after cardiac arrest in rats by increased brain mitochondrial biogenesis.

Glibenclamide Is Comparable to Target Temperature Management in Improving Survival and Neurological Outcome After Asphyxial Cardiac Arrest in Rats

Background

We previously have shown that glibenclamide (GBC), a sulfonylurea receptor 1–transient receptor potential M4 (SUR1‐TRPM4) channel inhibitor, improves survival and neurological outcome after asphyxial cardiac arrest and cardiopulmonary resuscitation (ACA/CPR). Here, we further compare the efficacy of GBC with target temperature management (TTM) and determine whether the efficacy of GBC is affected by TTM.

Methods and Results

Male Sprague‐Dawley rats (n=213) subjected to 10‐minute ACA/CPR were randomized to 4 groups after return of spontaneous circulation (ROSC): normothermia control (NT); GBC; TTM; and TTM+GBC. Survival, neurodeficit scores, histological injury, as well as the expressions of SUR1 and TRPM4 were evaluated. The 7‐day survival rate was 34.4% (11 of 32) in the NT group, 65% (13 of 20) in the GBC group, 50% (10 of 20) in the TTM group, and 70% (14 of 20) in the TTM+GBC group. Rats that received either GBC, TTM alone, or in combination showed less neurological deficit than NT control at 24, 48, and 72 hours and 7 days after ROSC. Moreover, TTM or GBC ameliorated neuronal degeneration and glial activation in the hippocampal CA1 region with similar efficacy, whereas the combination of them had a trend toward better effect. The subunits of SUR1‐TRPM4 heterodimers were both strongly upregulated after ACA/CPR and expressed in multiple types of brain cells, but partly suppressed by TTM.

Conclusions

GBC is comparable to TTM in improving survival and neurological outcome after ACA/CPR. When GBC is given along with TTM, less histological injury tended to be achieved.

Therapeutic effects of various methods of MSC transplantation on cerebral resuscitation following cardiac arrest in rats

In the present study, mesenchymal stem cells (MSCs) were transplanted into the brain of rats following cardiopulmonary resuscitation (CPR) by three different methods: Direct stereotaxic injection into the lateral cerebral ventricle (LV), intra-carotid administration (A), and femoral venous infusion (V). The three different methods were compared by observing the effects of MSCs on neurological function following global cerebral hypoxia-ischemia, in order to determine the optimum method for MSC transplantation. MSCs were transplanted in groups A, V and LV following the restoration of spontaneous circulation. Neurological deficit scale scores were higher in the transplantation groups, as compared with the control group. Neuronal damage, brain water content and serum levels of S100 calcium-binding protein B were reduced in the hippo-campus and temporal cortex of the transplantation groups, as compared with the control rats following resuscitation. MSCs were able to migrate inside the brain tissue following transplantation, and were predominantly distributed in the hippocampus and temporal cortex where the neurons were vulnerable during global cerebral ischemia. These results suggest that transplantation of MSCs may notably improve neurological function following CPR in a rat model. Of the three different methods of MSC transplantation tested in the present study, LV induced the highest concentration of MSCs in brain areas vulnerable to global cerebral ischemia, and therefore, produced the best neurological outcome.

Applications of electroencephalography to characterize brain activity: perspectives in stroke

A wide array of neuroimaging technologies are now available that offer unprecedented opportunities to study the brain in health and disease. Each technology has associated strengths and weaknesses that need to be considered to maximize their utility, especially when used in combination. One imaging technology, electroencephalography (EEG), has been in use for more than 80 years, but as a result of recent technologic advancements EEG has received renewed interest as an inexpensive, noninvasive and versatile technique to evaluate neural activity in the brain. In part, this is due to new opportunities to combine EEG not only with other imaging modalities, but also with neurostimulation and robotics technologies. When used in combination, noninvasive brain stimulation and EEG can be used to study cause-and-effect relationships between interconnected brain regions providing new avenues to study brain function. Although many of these approaches are still in the developmental phase, there is substantial promise in their ability to deepen our understanding of brain function. The ability to capture the causal relationships between brain function and behavior in individuals with neurologic disorders or injury has important clinical implications for the development of novel biomarkers of recovery and response to therapeutic interventions. The goals of this paper are to provide an overview of the fundamental principles of EEG; discuss past, present, and future applications of EEG in the clinical management of stroke; and introduce the technique of combining EEG with a form of noninvasive brain stimulation, transcranial magnetic stimulation, as a powerful synergistic research paradigm to characterize brain function in both health and disease.Video Abstract available (see Supplemental Digital Content 1, http://links.lww.com/JNPT/A87) for more insights from the authors.

Neuroprotective effects of quercetin in a mouse model of brain ischemic/reperfusion injury via anti-apoptotic mechanisms based on the Akt pathway

The present study provided experimental evidence for the neuroprotective effects of quercetin using a rat model of global brain ischemic/reperfusion (I/R) injury. Pre‑treatment with quercetin (5 or 10 mg/kg orally (p.o.); once daily) induced a dose‑dependent reduction in I/R‑induced hippocampal neuron cell loss, with 10 mg/kg/day being the lowest dose that achieved maximal neuroprotection. Administration of 10 mg/kg quercetin over at least 3 days prior to I/R was required to improve the survival rate of I/R rats. Fluorescence‑assisted cell sorting, hematoxylin and eosin staining and terminal deoxynucleotidyl transferase dUTP nick end labeling indicated neuronal cell loss in the CA1 hippocampus. Rats that had undergone transient global cerebral ischemia for 15 min followed by 1 h of reperfusion exhibited a significant increase in reactive oxygen species (ROS) production in the hippocampus. The I/R‑induced ROS overproduction in the hippocampus at 1, 12 and 24 h following I/R was significantly decreased by quercetin pre‑treatment. Western blot analysis revealed that the neuroprotective effects of quercetin (5 and 10 mg/kg/day, p.o.) were associated with an upregulation of the I/R‑induced suppression of B‑cell lymphoma‑2 (Bcl‑2), Bcl extra large and survivin expression as well as phosphorylation of Bcl‑2‑associated death promoter. Furthermore, the neuroprotective effects of quercetin (5, 10 mg/kg/day) in the brain were associated with an upregulation of Akt signaling. These findings suggested that the inhibition of I/R‑induced brain injury by quercetin likely involves a transcriptional mechanism to enhance anti‑apoptotic signaling.

Effects of mild hypothermia on the ROS and expression of caspase-3 mRNA and LC3 of hippocampus nerve cells in rats after cardiopulmonary resuscitation

BACKGROUND

Cardiac arrest (CA) is a common and serious event in emergency medicine. Despite recent improvements in resuscitation techniques, the survival rate of patients with CA is unchanged. The present study was undertaken to observe the effect of mild hypothermia (MH) on the reactive oxygen species (ROS) and the effect of neurological function and related mechanisms.

METHODS

Sixty-five healthy male Sprague Dawley (SD) adult rats were randomly (random number) divided into 2 groups: blank control group (n=5) and CPR group (n=60). CA was induced by asphyxia. The surviving rats were randomly (random number) divided into two groups: normothermia CPR group (NT) and hypothermia CPR group (HT). Normothermia of 37 °C was maintained in the NT group after return of spontaneous circulation (ROSC), hypothermal intervention of 32 °C was carried out in the HT group for 4 hours immediately after ROSC. Both the NT and HT groups were then randomly divided into 2 subgroups 12 hours and 24 hours after ROSC (NT-12, NT-24, HT-12, HT-24 subgroups). During observation, the neurological deficit scores (NDSs) was recorded, then the bilateral hippocampi were obtained from rats' head, and monoplast suspension of fresh hippocampus tissue was made immediately to determine the level of intracellular ROS by flow cytometry. Transmission electron microscope was used to observe the ultramicro changes of cellular nucleus and mitochondria. Reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the expression of caspase-3 mRNA, and western-blotting (WB) was used to determine the level of LC3 in frozen hippocampus tissue. Measured data were analyzed with paired sample t test and One-Way ANOVA.

RESULTS

Of 60 rats with CA, 44 (73%) were successfully resuscitated and 33 (55%) survived until the end of the experiment. The NDSs of rats in the NT and HT groups were more significantly reduced than those in the BC group (F=8.107, P<0.05), whereas the NDSs of rats in the HT-12 and HT-24 subgroups were significantly increased in comparison with those NDSs of rats in the NT-12 and NT-24 subgroups, respectively (t=9.692, P<0.001; t=14.374, P<0.001). The ROS in hippocampus nerve cells in the NT and HT groups significantly increased compared to the BC group (F=16.824, P<0.05), whereas the ROS in the HT-12 and HT-24 subgroups significantly reduced compared with that ROS in the NT-12 and NT-24 subgroups, respectively (t=9.836, P<0.001; t=7.499, P<0.001). The expression of caspase-3 mRNA in hippocampus nerve cells in the NT and HT groups were significantly increased compared to the BC group (F=24.527, P<0.05), whereas the expression of caspase-3 mRNA in rats of the HT-12 and HT-24 subgroups was significantly reduced compared to the NT-12 and NT-24 subgroups, respectively (t=6.935, P<0.001; t=4.317, P<0.001). The expression of LC3B-II/I in hippocampus nerve cells of rats in the NT and HT groups significantly increased compared to the BC group (F=6.584, P<0.05), whereas the expression of LC3B-II/I in rats of the HT-12 and HT-24 subgroups significantly reduced compared to the NT-12 and NT-24 subgroups, respectively (t=10.836, P<0.001; t=2.653, P=0.02). Ultrastructure damage of nucleus and mitochondria in the NT group was more evident than in the BC group, and eumorphism of nucleus and mitochondria were maintained in rats of the HT group compared with the NT group.

CONCLUSION

Mild hypothermia lessened the injury of nerve cells and improved the neurological function of rats that survived from cardiac arrest by reducing the ROS production of nerve cells and inhibiting the expression of caspase-3 mRNA and LC3, leading to cellular apoptosis and massive autophagy in rats that survived from cardiac arrest after CPR.

A comparative study of event-related coupling patterns during an auditory oddball task in schizophrenia

OBJECTIVE

The aim of this research is to explore the coupling patterns of brain dynamics during an auditory oddball task in schizophrenia (SCH).

APPROACH

Event-related electroencephalographic (ERP) activity was recorded from 20 SCH patients and 20 healthy controls. The coupling changes between auditory response and pre-stimulus baseline were calculated in conventional EEG frequency bands (theta, alpha, beta-1, beta-2 and gamma), using three coupling measures: coherence, phase-locking value and Euclidean distance.

MAIN RESULTS

Our results showed a statistically significant increase from baseline to response in theta coupling and a statistically significant decrease in beta-2 coupling in controls. No statistically significant changes were observed in SCH patients.

SIGNIFICANCE

Our findings support the aberrant salience hypothesis, since SCH patients failed to change their coupling dynamics between stimulus response and baseline when performing an auditory cognitive task. This result may reflect an impaired communication among neural areas, which may be related to abnormal cognitive functions.