Cardiopulmonary Resuscitation In Rats Research Articles

Molecular mechanism of HDAC6-mediated pyroptosis in neurological function recovery after cardiopulmonary resuscitation in rats

Brain injury after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) is the leading cause of neurological dysfunction and death. This study aimed to explore the mechanism of histone deacetylase 6 (HDAC6) in neurofunctional recovery following CA/CPR in rats. A rat model was established by CA/CPR treatment. Adenovirus-packaged sh-HDAC6 was injected into the tail vein. To evaluate the neurofunction of rats, survival time, neurofunctional scores, serum NSE/S100B, and brain water content were measured and Morris water maze test was performed. HDAC6, microRNA (miR)-138-5p, Nod-like receptor protein 3 (NLRP3), and pyroptotic factor levels were determined by real-time quantitative polymerase chain reaction or Western blot assay. HDAC6 and H3K9ac enrichment on miR-138-5p promoter were examined by chromatin immunoprecipitation. miR-138-5p-NLRP3 binding was analyzed by dual-luciferase reporter assay. NLRP3 inflammasome was activated with nigericin sodium salt. After CPR treatment, HDAC6 was highly expressed, while miR-138-5p was downregulated. HDAC6 downregulation improved neurofunction and reduced pyroptosis. HDAC6 enrichment on the miR-138-5p promoter deacetylated H3K9ac, inhibiting miR-138-5p, and promoting NLRP3-mediated pyroptosis. Downregulating miR-138-5p partially reversed the protective effect of HDAC6 inhibition after CPR. In Conclusion, HDAC6 enrichment on miR-138-5p promoter deacetylated H3K9ac, inhibiting miR-138-5p expression and promoting NLRP3-mediated pyroptosis, worsening neurological dysfunction in rats after CPR.

A ventricular fibrillation cardiac arrest model with extracorporeal cardiopulmonary resuscitation in rats: 8 minutes arrest time leads to increased myocardial damage but does not increase neuronal damage compared to 6 minutes.

Extracorporeal cardiopulmonary resuscitation (ECPR) is an emerging strategy in highly selected patients with refractory cardiac arrest (CA). Animal models can help to identify new therapeutic strategies to improve neurological outcome and cardiac function after global ischemia in CA. Aim of the study was to establish a reproducible ECPR rat model of ventricular fibrillation CA (VFCA) that leads to consistent neuronal damage with acceptable long-term survival rates, which can be used for future research. Male Sprague Dawley rats were resuscitated with ECPR from 6 min (n = 15) and 8 min (n = 16) VFCA. Animals surviving for 14 days after return of spontaneous resuscitation (ROSC) were compared with sham operated animals (n = 10); neurological outcome was assessed daily until day 14. In the hippocampal cornu ammonis 1 region viable neurons were counted. Microglia and astrocyte reaction was assessed by Iba1 and GFAP immunohistochemistry, and collagen fibers in the myocardium were detected in Azan staining. QuPath was applied for quantification. Of the 15 rats included in the 6 min CA group, all achieved ROSC (100%) and 10 (67%) survived to 14 days; in the 8 min CA group, 15 (94%) achieved ROSC and 5 (31%) reached the endpoint. All sham animals (n = 10) survived 2 weeks. The quantity of viable neurons was significantly decreased, while the area displaying Iba1 and GFAP positive pixels was significantly increased in the hippocampus across both groups that experienced CA. Interestingly, there was no difference between the two CA groups regarding these changes. The myocardium in the 8 min CA group exhibited significantly more collagen fibers compared to the sham animals, without differences between 6- and 8-min CA groups. However, this significant increase was not observed in the 6 min CA group. Our findings indicate a uniform occurrence of neuronal damage in the hippocampus across both CA groups. However, there was a decrease in survival following an 8-min CA. Consequently, a 6-min duration of CA resulted in predictable neurological damage without significant cardiac damage and ensured adequate survival rates up to 14 days. This appears to offer a reliable model for investigating neuroprotective therapies.

Abstract 318: Improvement In Cerebral Blood Flow Assessed By A Laser Speckle Imaging After Extracorporeal Cardiopulmonary Resuscitation In Rats

Introduction: The effect of extracorporeal cardiopulmonary resuscitation (ECPR) on recovery of cerebral blood flow (CBF) after achieving a return of spontaneous circulation (ROSC) has been undetermined. The objective of this study was to determine the impact of ECPR on the changes of CBF post-ROSC in a rat model of prolonged cardiac arrest (CA) and ECPR. Methods and Results: Adult Sprague-Dawley male rats (400- 500g) were subjected to 20-min of asphyxia CA whereupon animals were mechanically ventilated and resuscitated by conventional manual chest compression (CCPR, n = 6) or ECPR using venous-arterial cardiopulmonary bypass (ECPR, n = 5). Epinephrine was (20 μg/kg) intravenously injected once during CCPR but not ECPR. In the ECPR group, cardiopulmonary bypass was weaned 30 min after ROSC. ROSC was defined as achieving a mean arterial pressure > 60 mmHg. Serial changes in CBF were measured at baseline and 2 h after ROSC using the laser speckle imaging system. There was no difference in time to CA and time to ROSC as well as hemodynamics for 2 h after ROSC between the two groups. Representative CBF images at 0, 10, 60, and 120 min after ROSC are shown in Fig. 1A. As expected, CCPR resulted in a hyperemic phase at 10 min and then a hypoperfusion phase (~ 50 % of CBF reduction from baseline) at 60 min or later after ROSC. In the ECPR group, CBF maintained at baseline level even at 60 and 120 min after ROSC. Further, CBF levels at 60 and 120 min after ROSC were markedly higher in the ECPR group than in the CCPR group ( Fig. 1B ). Conclusions: Our data using laser speckle imaging suggests that ECPR is likely to improve CBF shortly after ROSC compared to CCPR.

Carbon monoxide-releasing molecule-2 ameliorates postresuscitation myocardial dysfunction in rat via mitochondrial-mediated apoptosis pathway and the regulation of mitochondrial dynamics

Mitochondrial dysfunction plays a significant role in the development of postresuscitation myocardial dysfunction (PRMD). Endogenous carbon monoxide (CO) has obvious protective effects on cardiomyocytes and that mitochondria are considered to be the main targets of CO action. This study aimed to investigate whether exogenous CO (carbon monoxide releasing molecule 2, CORM-2) could protect against PRMD, and improve cardiac function in rats via the mitochondria pathway. Forty male Sprague-Dawley rats were randomly divided into five groups: sham group, model cardiopulmonary resuscitation (CPR) group, CORM-2 treatment group, inactivated CORM-2 group, and DMSO (Dimethyl sulfoxide, CORM-2 vehicle) group. Excluding the sham group, all groups underwent CPR 4 min after cardiac arrest (CA), animals in every group underwent surgery for catheter insertion before the CA-CPR. In the treatment groups, CORM-2 and inactivated CORM-2 (both 4 mg/kg, dissolved in 2% dimethyl sulfoxide and diluted in normal saline) were intraperitoneally injected 12 h before CPR was started. In the sham, model CPR, and vehicle groups, animals were administered normal saline or vehicle as appropriate. The results demonstrated that the mitochondrial ultrastructure abnormalities in CORM-2 group was less severe than CPR rats. CORM-2 alleviated myocardial contractile and diastolic dysfunction after CPR, decreased caspase-3 and caspase-9 expression in myocardial tissues, and meanwhile suppressed cytochrome c release from mitochondria. Furthermore, CORM-2 lessen the production of reactive oxygen species (ROS) and increased myocardial mitochondrial respiratory complex IV enzyme activity after CPR. Dynamin-related protein 1（Drp1) was significantly less expressed in CORM-2 group with high expression of mitofusion-2 (Mfn2), suggesting that CORM-2 can promote mitochondrial fusion and reduce mitochondrial fission. Collectively, we provide the evidence that CORM-2 effectively relieved myocardial injury after CPR in rats, protected myocardial mitochondria, and preserved cardiac function after resuscitation. The proposed mechanisms of action were improved mitochondrial respiratory function, maintained mitochondrial dynamics balance, and suppressed the mitochondrial-mediated apoptosis.

Ac2-26 Alleviates Brain Injury after Cardiac Arrest and Cardiopulmonary Resuscitation in Rats via the eNOS Pathway.

Background Brain injury is the leading cause of death following cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Ac2-26 and endothelial nitric oxide synthase (eNOS) have been shown to reduce neuroinflammation. This study is aimed at determining the mechanism by which Ac2-26 protects against inflammation during brain injury following CA and CPR. Methods Sixty-four rats were randomized into sham, saline, Ac2-26, and Ac2-26+L-NIO (endothelial nitric oxide synthase (eNOS) inhibitor) groups. Rats received Ac2-26, Ac2-26+L-NIO, or saline after CPR. Neurologic function was assessed at baseline, 24, and 72 hours after CPR. At 72 hours after resuscitation, serum and brain tissues were collected. Results Blood-brain barrier (BBB) permeability increased, and the number of surviving neurons and neurological function decreased in the saline group compared to the sham group. Anti-inflammatory and proinflammatory factors, neuron-specific enolase (NSE) levels, and the expression of eNOS, phosphorylated (p)-eNOS, inducible nitric oxide synthase (iNOS), and oxidative stress-related factors in the three CA groups significantly increased (P < 0.05). BBB permeability decreased, and the number of surviving neurons and neurological function increased in the Ac2-26 group compared to the saline group (P < 0.05). Ac2-26 increased anti-inflammatory and reduced proinflammatory markers, raised NSE levels, increased the expression of eNOS and p-eNOS, and reduced the expression of iNOS and oxidative stress-related factors compared to the saline group (P < 0.05). The effect of Ac2-26 on brain injury was reversed by L-NIO (P < 0.05). Conclusions Ac2-26 reduced brain injury after CPR by inhibiting oxidative stress and neuroinflammation and protecting the BBB. The therapeutic effect of Ac2-26 on brain injury was largely dependent on the eNOS pathway.

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

Objective We 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.

Inhibition of microRNA-155 Alleviates Neurological Dysfunction Following Transient Global Ischemia and Contribution of Neuroinflammation and Oxidative Stress in the Hippocampus.

Central pro-inflammatory cytokine (PIC) signal is involved in neurological deficits after transient global ischemia induced by cardiac arrest (CA). The present study was to examine the role of microRNA- 155 (miR-155) in regulating IL-1β, IL-6 and TNF-α in the hippocampus of rats with induction of CA. We further examined the levels of products of oxidative stress 8-isoprostaglandin F2α (8-iso PGF2α, indication of oxidative stress); and 8-hydroxy-2'-deoxyguanosine (8-OHdG, indication of protein oxidation) after cerebral inhibition of miR-155. CA was induced by asphyxia and followed by cardiopulmonary resuscitation in rats. ELISA and western blot analysis were used to determine the levels of PICs and products of oxidative stress; and the protein expression of NADPH oxidase (NOXs) in the hippocampus. In addition, neurological severity score and brain edema were examined to assess neurological functions. We observed amplification of IL-1β, IL-6 and TNF-α along with 8-iso PGF2α and 8-OHdG in the hippocampus of CA rats. Cerebral administration of miR-155 inhibitor diminished upregulation of PICs in the hippocampus. This also attenuated products of oxidative stress and upregulation of NOX4. Notably, inhibition of miR-155 improved neurological severity score and brain edema and this was linked to signal pathways of PIC and oxidative stress. We showed the significant role of blocking miR-155 signal in improving the neurological function in CA rats likely via inhibition of signal pathways of neuroinflammation and oxidative stress, suggesting that miR-155 may be a target in preventing and/or alleviating development of the impaired neurological functions during CA-evoked global cerebral ischemia.

MiR-126 suppresses neuronal apoptosis in rats after cardiopulmonary resuscitation via regulating p38MAPK

In this study, we aimed to evaluate the effect of microRNA-126 (miR-126) on neuronal apoptosis in cardiopulmonary resuscitation rats and to explore the related molecular mechanism. The expression of miR-126 in brain tissues of rats after cardiopulmonary resuscitation was measured by real-time fluorescence quantitative polymerase chain reaction (RT-qPCR). The basic parameters of cardiopulmonary resuscitation were recorded by miR-126 mimic injection in rats after cardiopulmonary resuscitation. Hematoxylin-eosin staining was used to observe the pathological changes of hippocampus. Immunohistochemistry was used to observe the expression of p38 and caspase-3 protein. Furthermore, the expression of p38 mitogen-activated protein kinase (p38MAPK), Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase 1/2 (ERK1/2) in rat hippocampus was detected by RT-qPCR and Western blot. In order to confirm whether miR-126 takes part in the p38MAPK pathway in the hippocampus of rats after cardiopulmonary resuscitation, the p38MAPK pathway inhibitor (SB203580) and activator (anisomycin) were added. The results showed overexpression of miR-126 could significantly increase the neurological function score and improve the pathological morphology of hippocampus in rats after cardiopulmonary resuscitation. miR-126 overexpression also could reduce the neuronal apoptosis, p38, and caspase-3 expression in the hippocampus. Moreover, the p38MAPK and JNK expression was downregulated and ERK1/2 expression was upregulated after miR-126 mimic injection (p < 0.05). The results of inhibition of p38MAPK pathway were consistent with those of overexpression of miR-126 (p > 0.05). This study indicated miR-126 could significantly reduce neuronal apoptosis of hippocampus in rats after cardiopulmonary resuscitation, which might be involved in the regulation of p38MAPK pathway.

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.

Effect of ulinastatin combined with mild therapeutic hypothermia on intestinal barrier dysfunction following cardiopulmonary resuscitation in rats.

The aim of the present study was to investigate the effect of ulinastatin (UTI) alone or combined with mild therapeutic hypothermia (MTH) on intestinal barrier dysfunction following cardiopulmonary resuscitation (CPR) in rats. A total of 25 adult male Sprague-Dawley rats were randomly organized into five groups: Sham; control; UTI; MTH; and the combined group. The latter four groups were induced with the asphyxiated cardiac arrest rat model and treated with different interventions. After 6 h of treatment, the intestinal tissues of the rats were examined by electron microscopy, and the levels of intestinal malondialdehyde (MDA) and superoxide dismutase (SOD) were determined. The results of the present study indicated that the target temperature had successfully been attained in MTH and the combined group, and the other three groups of rats all survived at a normal temperature. In the rats treated with UTI or MTH, the epithelial cells exhibited pathological changes in their tight junctions and epithelial cell surface microvilli compared with the sham group. In the rats treated with a combination of UTI and MTH, whilst the epithelial cells exhibited a few slight changes, including mitochondrial edema, they were largely similar to the normal epithelial cells. However, there were significant differences in the levels of MDA and SOD between the different treatment groups. UTI combined with MTH may serve a protective role by suppressing oxidative stress in the small intestinal mucosa following CPR in rats compared with either UTI or MTH treatment alone.

Ultrasound improves the outcomes of cardiopulmonary resuscitation in rats by stimulating the cholinergic anti‑inflammatory pathway.

The present study investigated the effects of the ultrasound (US), a noninvasive technique, on ischemia-reperfusion injury (IRI) following cardiopulmonary resuscitation (CPR). The animals used in the present study were randomized into five groups (n=8 per group) as follows: i) The CPR group, where the rats underwent 6 min of untreated ventricular fibrillation (VF) followed by CPR and defibrillation; ii) the US group, in which the treatment was identical to the CPR group with the exception that rats were exposed to US treatment 24 h prior to CPR; iii) the MLA group, in which the treatment was identical to the US group with the exception that the α7 nicotinic acetylcholine receptor (α7nAChR) antagonist MLA (4 mg/kg) was administered 30 min prior to US and VF respectively; iv) the GTS group, in which the treatment was identical to the CPR group with the exception that the α7nAChR agonist GTS-21 (4 mg/kg) was injected 30 min prior to VF; and v) the SHAM group, in which the rats were exposed to surgical preparation without CPR and US application. At 1 day prior to CPR, the US treatment was administered to the left kidney by US pulses (contrast general mode with 9 MHz) with a bursting mechanical index of 0.72 for 2 min. Following treatment of the left kidney, the right kidney was exposed to identical US treatment for an additional 2 min. The results demonstrated that US preconditioning decreased the number of defibrillations required and shortened the duration of CPR. US also suppressed tumor necrosis factor-α and interleukin-6 levels following resuscitation (P<0.05), and a significantly longer overall survival time was observed in the US-treated animals (P<0.01). In addition, US attenuated neuronal injury and promoted the expression of α7nAChR in hippocampal neurons (P<0.05). However, the protective effects of US were abolished by MLA and imitated by GTS-21. The results of the present study demonstrated that prior exposure to US may improve animal outcomes following CPR, and the protective effects of US may be dependent on the cholinergic anti-inflammatory pathway (CAP) via α7nAChR.

Xuezhikang improves the outcomes of cardiopulmonary resuscitation in rats by suppressing the inflammation response through TLR4/NF-κB pathway

Background/AimsXuezhikang (XZK), a red yeast rice extract with lipid-lowering effect, contains a family of naturally statins, such as lovastatin. In recent years, its effect beyond the regulation of lipids has also been received increasing attention. Therefore, the purpose of this study was to explore the protective effects and possible molecular mechanisms of XZK on brain injury after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR), and to investigate whether it has a dose-dependent effect and the difference with lovastatin. MethodsRats were treated with low-dose XZK (XZK-L, 20 mg/kg/d), high-dose XZK (XZK-H, 200 mg/kg/d) and lovastatin by gavage once daily for 2 weeks before CA. The levels of TNF-α, IL-6 and IL-1β were evaluated at 1, 4, and 72 h post-CA/CPR. The survival rate, neurological deficit score (NDS), and expression of TLR4, phosphorylated NF-κB and TNF-α in hippocampal tissues were evaluated at 72 h post-CA/CPR. ResultsCA/CPR induced a significant increase in serum TNF-α, IL-6 and IL-1β, as well as increased expressions of TLR4, phosphorylated NF-κB and TNF-α in the hippocampus. Both low-dose and high-dose XZK treatment inhibited the expression of these inflammatory cytokines. In addition, it reduced the number of defibrillations and shortened the duration of CPR required for return of spontaneous circulation (ROSC). XZK treatment also improved neurological function and 72-hour survival rate in rats. However, high-dose XZK was superior to lovastatin in the suppression of IL-1β mRNA level and TNF-α protein level in hippocampal tissue after CPR. There were no significant differences observed among high-dose XZK, low-dose XZK and lovastatin groups in other respects. ConclusionThese results indicated that XZK had a protective effect against brain injury post-CA/CPR. The mechanisms underlying the protective effects of XZK may be related to the suppressing of CA/CPR-induced inflammatory response through the inhibiting TLR4/NF-κB signaling pathway.

A Combination of Ulinastatin and Xuebijing Amplifies Neuroprotection after Transient Cerebral Ischemia via Attenuating Apoptosis Signal Pathways in Hippocampus.

Ulinastatin (UTI) plays the beneficial roles in modifying cerebral ischemic injury evoked by cardiac arrest (CA). XueBiJing (XBJ), comprised of extracts from Chinese herbals, has been used for the treatment of sepsis and ischemic disorders linked to multiple organ dysfunction syndromes. The current study was to find interventions that can enhance effectiveness of these drugs and further to provide a fundamental for their rational application in clinical practice. Thus, we examined how apoptosis signal in the hippocampus is engaged in a facilitating role of UTI and XBJ in improving neural injury and neurological functions after transient cerebral ischemia. CA was induced by asphyxia followed by cardiopulmonary resuscitation in rats. Western Blot analysis and ELISA were employed to determine the protein expression of Caspase-3 and Caspase-9 in the hippocampus; and representative apoptosis pathways. The modified neurological severity score (mNSS) and spatial working memory performance were used to assess neurological deficiencies in CA rats. CA increased Caspase-3 and Caspase-9 in the hippocampus CA1 region. A lower dose of UTI did not attenuate upregulation of apoptosis signal pathways evoked by CA. However, a systemic administration of XBJ significantly amplified the inhibitory effects of the lower dose of UTI on apoptosis signal of the hippocampus. In addition, a combination of UTI and XBJ improved mNSS and spatial working memory performance to a greater degree. Our data indicate that a combination of XBJ and UTI plays a facilitating role in improving neuronal injury and neurological deficits observed in transient cerebral ischemia; and an inhibition of apoptosis signal pathways is involved in neuroprotective effects of united XBJ and UTI.

Inhibition of RHO Kinase by Fasudil Attenuates Ischemic Lung Injury After Cardiac Arrest in Rats.

Lung injury is a common complication after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR), and Rho kinase (ROCK) may be involved in the process of this injury. In this study, we aimed to study the effects of ROCK inhibition by fasudil on lung injury induced by asphyxial CA and CPR in rats. A total of 130 rats were randomized into three groups: Sham, Control, and Fasudil intervention group. Animals in the Fasudil intervention group were intraperitoneally administered with 10 mg/kg of the drug, 1 h before inducing CA. Rats in the Control group received equivalent volume of saline and were subjected to the same experimental procedures with as the Fasudil group. Blood was collected and lungs were harvested at 3, 6, 12, 24, and 48 h after return of spontaneous circulation (ROSC) for blood gas and biochemical analysis. Fasudil significantly increased the partial pressure of oxygen and pH in arterial blood, as well as attenuated lung histological injury and lung edema after ROSC. Additionally, it significantly decreased lung inflammatory response (decreased levels of tumor necrosis factor-α and interleukin-6, and myeloperoxidase activity) and oxidative stress (decreased malonaldehyde level and increased superoxide dismutase activity) after ROSC. Using western blot analysis, we found that fasudil inhibited both isoforms ROCK1 and ROCK2, and intercellular adhesion molecule-1; nevertheless, it increased vascular endothelial cadherin protein expression after ROSC. Our study suggested that the Rho kinase signaling pathway is critical for CA-induced lung injury and fasudil has protective effects on lung injury after CA and CPR.

Improved Outcomes of Cardiopulmonary Resuscitation in Rats Treated With Vagus Nerve Stimulation and Its Potential Mechanism.

Studies have demonstrated that vagus nerve stimulation (VNS) reduces ischemia/reperfusion injury. In this study, we investigated the protective effects of VNS in a rat model of cardiopulmonary resuscitation (CPR). We further investigated whether the beneficial effects of VNS were dependent on the alpha 7 nicotinic acetylcholine receptor (α7nAChR). Forty animals were randomized into four groups and all underwent CPR (n = 10 each): CPR alone (control); VNS during CPR; α7nAChR antagonist methyllycaconitine citrate (MLA) with VNS; α7nAChR agonist 3-(2, 4-dimethoxybenzylidene) anabaseine (GTS-21 dihydrochloride) without VNS. The right vagus nerve was exteriorized in all animals. Ventricular fibrillation was induced and untreated for 8 min. Defibrillation was attempted after 8 min of CPR. VNS was initiated at the beginning of precordial chest compressions and continued for 4 h after return of spontaneous circulation (ROSC) in both the VNS and MLA groups. Hemodynamic measurements and myocardial function, including ejection fraction and myocardial performance index, were assessed at baseline, 1 and 4 h after ROSC. The neurological deficit score was measured at 24-h intervals for a total of 72 h. The heart rate was reduced in the VNS and MLA groups, while no difference was found in mean arterial pressure between the four groups. Better post-resuscitation myocardial and cerebral function and longer duration of survival were observed in the VNS-treated animals. The protective effects of VNS could be abolished by MLA and imitated by GTS-21. In addition, VNS decreased the number of electrical shocks and the duration of CPR required. VNS improves multiple outcomes after CPR.

The effect of mild hypothermia on Nogo-A and neurological function in the brain after cardio-pulmonary resuscitation in rats

The aim of the current study was to investigate dynamic changes in brain Nogo-A protein in rats, and the effects of mild hypothermia therapy on its expression after Cardio-Pulmonary Resuscitation (CPR). Western-blotting and neurological scoring of 45 rats subjected to cardiac arrest and CPR were performed to investigate the expression of Nogo-A protein in the hippocampus and cortex 6 h, 12 h, 24 h, 48 h, and 72 h after restoration of spontaneous circulation (ROSC). Nogo-A expression levels gradually increased from 6 h after CPR in the brain. In the hippocampus and cortex, Nogo-A exhibited a unimodal waveform-first it increased, but then it decreased. It peaked at 24 h in the hippocampus, and at 48 h in the cortex. The expression of Nogo-A in the mild hypothermia group was significantly lower at 12 h (p<0.05). Mild hypothermia can reduce the expression of Nogo-A protein in the hippocampus and cortex after CPR, which may be one of the mechanisms that play a role in cerebral protection.

Tea polyphenols down-regulate JNK phosphorylation to inhibit neuron apoptosis in rats with cardiac arrest

To study the effect of tea polyphenols (TP) on c-Jun N-terminal kinase 1/2 (JNK1/2) phosphorylation and cell apoptosis in brain tissues in rats with cardiac arrest (CA) following cardiopulmonary resuscitation (CPR). Healthy male Sprague-Dawley (SD) rats were randomly divided into sham group (n = 6), CA group (n = 12), and TP group (n = 12). The rats in CA and TP groups were induced ventricular fibrillation (VF) via esophagus stimulation with alternating current. Five minutes after CA, CPR was performed. Once restoration of spontaneous circulation (ROSC) was gained, normal saline (NS) and TP were injected intravenously in CA and TP groups with 10 mg/kg, respectively. Cortex of 6 rats in each group was harvested at 12 hours and 72 hours after ROSC. Cortex of sham group was harvested at 72 hours after operation without VF induction. The expressions of phosphorylated JNK1/2 (p-JNK1/2), JNK1/2, caspase-3, Bax and Bcl-2 were measured by Western Blot. Cell apoptosis was detected by TdT-mediated dUTP nick end labeling (TUNEL), and p-JNK/TUNEL double positive cells were detected by fluorescence double staining. Compared with sham group, the expressions of p-JNK, caspase-3 and Bax were increased, the expression of Bcl-2 was declined, and the apoptotic cells were significantly increased at 72 hours after ROSC in CA group. Compared with CA group, the phosphorylation of JNK was significantly declined at 12 hours and 72 hours after ROSC in TP group (the ratio of p-JNK1/2 and JNK1/2: 3.200±0.060 vs. 5.700±0.210, 1.400±0.060 vs. 5.400±0.090, both P < 0.05), the expressions of caspase-3 and Bax were decreased [caspase-3 (gray value): 42.00±5.23 vs. 54.00±7.84, 38.74±4.60 vs. 58.68±7.19; Bax (gray value): 38.04±6.21 vs. 68.76±6.08, 58.84±7.99 vs. 70.03±7.36, all P < 0.05], the expression of Bcl-2 was increased (gray value: 37.36±3.11 vs. 28.47±7.46, 48.78±6.55 vs. 29.54±3.13, both P < 0.05); the cell apoptosis rate was reduced at 72 hours [(31.14±4.51)% vs. (45.87±3.95)%, P < 0.01], and p-JNK/TUNEL double positive cells/TUNEL cells ratio was significantly decreased (10.00±0.85 vs. 52.70±3.05, P < 0.01). The inhibition of neuron apoptosis caused by TP after CPR in rats with CA is related to the inhibition of JNK1/2 phosphorylation.

Effects of mild hypothermia on expression of NF-E2-related factor 2 and heme-oxygenase-1 in cerebral cortex and hippocampus after cardiopulmonary resuscitation in rats.

Objective(s):The aim of this study was to investigate the effects of mild hypothermia on expression of NF-E2-related factor 2 (Nrf2) and heme-oxygenase-1 (HO-1) of rat cerebral cortex and hippocampus after cardiopulmonary resuscitation and further investigate the possible mechanism of action.Material and Methods:To copy an asphyxia heart arrest model, Sprague Dawley rats were randomly divided into normothermia group, mild hypothermia group before restoration of spontaneous circulation (ROSC), and mild hypothermia group after ROSC. Body temperature in normothermia group was maintained at 37.5-39 °C, while in mild hypothermia group maintained at 32-34 °C by surface cooling with the ice pack. Each group then divided into three subgroups: 15 min, 30 min, and 60 min. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to detect the expression of Nrf2 and HO-1 mRNA in cerebral cortex and hippocampus. Hematoxylin-eosin (H&E) staining was performed to observe histological changes. Immunohistochemistry was performed to detect the expression of Nrf2 and HO-1 protein expression.Results:The expression of Nrf2 and HO-1 in cerebral cortex and hippocampus after cardiopulmonary resuscitation (CPR) was significantly increased and mild hypothermia up regulated this level. HE staining showed that mild hypothermia significantly improved neuronal injury.Conclusion:Mild hypothermia has neuroprotective effects on cerebral ischemia/reperfusion injury after cardiac arrest. The possible mechanism is that Nrf2-ARE pathway in cerebral cortex and hippocampus after CPR is activated.

Rosuvastatin improves myocardial and neurological outcomes after asphyxial cardiac arrest and cardiopulmonary resuscitation in rats.

Rosuvastatin, a potent HMG-CoA reductase inhibitor, is cholesterol-lowering drugs and reduce the risk of myocardial infarction and stroke. This study is to explore whether rosuvastatin improves outcomes after cardiac arrest in rats. Male Sprague-Dawley rats were subjected to 8min of cardiac arrest (CA) by asphyxia and randomly assigned to three experimental groups immediately following successful resuscitation: Sham; Control; and Rosuvastatin. The survival, hemodynamics, myocardial function, neurological outcomes and apoptosis were assessed. The 7-d survival rate was greater in the rosuvastatin treated group compared to the Control group (P=0.019 by log-rank test). Myocardial function, as measured by cardiac output and ejection fraction, was significantly impaired after CA and notably improved in the animals treated with rosuvastatin beginning at 60min after return of spontaneous circulation (ROSC) (P<0.05). Moreover, rosuvastatin treatment significantly ameliorated brain injury after ROSC, which was characterized by the increase of neurological function scores, and reduction of brain edema in cortex and hippocampus (P<0.05). Meanwhile, the levels of cardiac troponin T and neuron-specific enolase and the caspase-3 activity were significantly decreased in the Rosuvastatin group when compared with the Control group (P<0.05). In conclusion, rosuvastatin treatment substantially improves the 7-d survival rate as well as myocardial function and neurological outcomes after ROSC.

GW27-e1192 CB1 receptor attenuate neurons apoptosis to improve the outcome of Win55, 212-2 inducing hypothermia after cardiopulmonary resuscitation in rats

To investigate whether the CB1 receptor attenuate neurons apoptosis to improve the outcome of Win55,212-2 inducing hypothermia after cardiopulmonary resuscitation. Cardiac Arrest (CA) was induced by transoesophageal ventricular pacing in Sprague-Dawley rats. 5min after onset of CA, cardiopulmonary