Neuroprotective Effect of Acute Ethanol Administration in a Rat With Transient Cerebral Ischemia

Influence of alcohol on in-hospital survival rate among patients with traumatic brain injury: a nationwide cohort study

BACKGROUND

The impact of alcohol on the prognosis of patients with traumatic brain injury (TBI) remains unclear. While some reports suggest that alcohol may exert neuroprotective effects, others indicate that it can worsen neurological outcomes. This study aimed to evaluate the influence of alcohol consumption on TBI outcomes using a nationwide database in Japan.

METHODS

We analyzed data from approximately 290 hospitals contributing to the Japan Trauma Data Bank between 2004 and 2018. Patients with head injuries and documented pre-injury alcohol consumption were included. To adjust for potential confounders and institutional clustering, we employed propensity score methods-specifically inverse probability weighting (IPTW) and overlap weighting-and conducted multiple logistic regression with a generalized estimating equation. Covariates in the propensity score model included age, sex, day of the week, time of injury, period of injury, and past medical history. The primary outcome was in-hospital survival. Additionally, we fitted a multivariate logistic regression model (with survival as the outcome) to identify potential interactions and confounders. This model included type of trauma (blunt or penetrating), cause and setting of trauma, head Abbreviated Injury Scale score, multiple trauma status, the Injury Severity Score, and the propensity score.

RESULTS

Of the 83,789 patients who met the inclusion criteria, 15,752 had reported alcohol consumption prior to injury (alcohol group) and 68,037 did not (non-alcohol group). In-hospital survival was 91.5% in the alcohol group and 86.4% in the non-alcohol group (risk difference: 5.2%; 95% CI: 4.7-5.7). After adjustment, the alcohol group maintained a higher in-hospital survival rate (IPTW: 92.0% vs. 86.1%, risk difference: 6.2%; 95% CI: 5.9-6.2; overlap weighting: 91.7% vs. 85.4%, risk difference: 7.0%; 95% CI: 6.1-7.8). In the multivariate logistic regression, preinjury alcohol consumption was associated with higher survival (odds ratio: 1.58, 95% CI: 1.47-1.70, p < 0.001).

CONCLUSIONS

In this nationwide study, preinjury alcohol consumption was associated with higher in-hospital survival among patients with TBI. Further research is warranted to elucidate the underlying mechanisms and confirm these findings in more diverse populations.

Severe Traumatic Brain Injury Outcomes in Patients with Premorbid Psychiatric Illness

OBJECTIVE

Individuals with psychiatric illnesses (PIs) have increased rates of traumatic brain injury (TBI). Nonetheless, the influence of underlying PI on TBI outcomes is poorly understood.

METHODS

We analyzed the medical records of 633 adult-severe TBI patients admitted to our institution between 2010 and 2021. We identified patients with premorbid PI (Psych (+) group, n = 129) and a subset with only a substance use disorder (SUD (+) group, n = 60) and compared them to patients without PI (Psych (-) group, n = 480). Outcome measures included discharge Glasgow Coma Scale (GCS), length of stay, in-hospital survival, and Glasgow Outcome Scale-Extended (GOS-E).

RESULTS

The Psych (+) group had increased in-hospital survival (69.8% vs. 55.0%, P = 0.003) and fewer patients with severe (3-8) discharge-GCS (28.7% vs. 46.0%, P < 0.001). The SUD (+) group had increased in-hospital survival (70.0% vs. 55.0%, P = 0.028) and fewer patients with severe discharge-GCS (28.3% vs. 46.0%, P = 0.009). However, the Psych (+) (21.0 vs. 10.0 days, P < 0.001) and SUD (+) (16.0 v. 10.0 days, P = 0.011) groups had longer length of stay. The Psych (+) group had a higher mean GOS-E at discharge (2.7 vs. 2.4, P = 0.004), 6-months (3.8 vs. 3.0, P = 0.006) and 1-year (3.4 vs. 2.3, P = 0.027). The SUD (+) group also had a higher mean GOS-E at discharge (2.8 vs. 2.4, P = 0.034), six months (3.8 vs. 3.0, P = 0.035), and one year (3.5 vs. 2.3, P = 0.008). Additionally, there were no significant differences in injury severity or computed tomography scan findings.

CONCLUSIONS

Individuals with PI and SUD appeared to have better outcomes but more complicated hospital stays following severe TBI. Future studies should investigate the mechanisms underlying these outcomes.

Neuroprotective Potential of Nitroglycerin in Ischemic Stroke: Insights into Neural Glucose Metabolism and Endoplasmic Reticulum Stress Inhibition

BACKGROUND

Glyceryl trinitrate (GTN), also known as nitroglycerin, is predominantly recognized as a vasodilator for ischemic heart disease, and its potential neuroprotective properties in acute ischemic stroke remain under exploration. We sought to discover the therapeutic advantages and mechanisms of post-recanalization GTN administration in acute ischemic stroke.

METHODS AND RESULTS

A total of 118 male Sprague-Dawley rats were divided into groups: sham, transient/permanent middle cerebral artery occlusion (MCAO) with or without GTN treatment, and transient/permanent MCAO treated with both GTN and KT5823, an inhibitor of PKG. Acute ischemic stroke was induced by transient MCAO for 2 hours followed by 6 or 24 hours of reperfusion and permanent MCAO (28-hour MCAO without reperfusion). The study assessed infarct volumes, neurological deficits, glucose metabolism metrics, NO, and cGMP levels via ELISA. mRNA and protein expression of key molecules of hyperglycolysis, gluconeogenesis, endoplasmic reticulum stress as well as signaling molecules (PKG, AMPK) were conducted via reverse transcription polymerase chain reaction and Western blotting, and cell death was assessed with TUNEL and ELISA. GTN significantly reduced cerebral infarct volumes, neurological deficits, and cell death only after transient MCAO. GTN led to a significant reduction in the expression of NO and cGMP levels, key glucose metabolism, endoplasmic reticulum stress-related genes and proteins, and phosphorylated AMPK while boosting PKG expression, in transient MCAO but not permanent MCAO. The GTN-induced reduction in glucose metabolites, lactate, and reactive oxygen species was exclusive to transient MCAO groups. Coadministration of GTN and PKG inhibitors reversed the observed GTN benefits.

CONCLUSIONS

GTN induced neuroprotection in transient MCAO by improving glucose metabolism and potentially controlling endoplasmic reticulum stress through the NO-cGMP-PKG signaling cascade to inhibit AMPK phosphorylation.

A Systematic Review and Meta-Analysis of Therapeutic Hypothermia and Pharmacological Cotherapies in Animal Models of Ischemic Stroke

Therapeutic hypothermia (TH) lessens ischemic brain injury. Cytoprotective agents can augment protection, although it is unclear which combinations are most effective. The objective of this study is to identify which cytoprotective drug works best with delayed TH. Following PRISMA guidelines, a systematic review (PubMed, Web of Science, MEDLINE, Scopus) identified controlled experiments that used an in vivo focal ischemic stroke model and evaluated the efficacy of TH (delay of ≥1 hour) coupled with cytoprotective agents. This combination was our main intervention compared with single treatments with TH, drug, or no treatment. Endpoints were brain injury and neurological impairment. The CAMARADES checklist for study quality and the SYRCLE's risk of bias tool gauged study quality. Twenty-five studies were included. Most used young, healthy male rats, with only one using spontaneously hypertensive rats. Two studies used mice models, and six used adult animals. Study quality was moderate (median score = 6), and risk of bias was high. Pharmacological agents provided an additive effect on TH for all outcomes measured. Magnesium coupled with TH had the greatest impact compared with other agent-TH combinations on all outcomes. Longer TH durations improved both behavioral and histological outcomes and had greater cytoprotective efficacy than shorter durations. Anti-inflammatories were the most effective in reducing infarction (standardized mean difference [SMD]: -1.64, confidence interval [CI]: [-2.13, -1.15]), sulfonylureas reduced edema the most (SMD: -2.32, CI: [-3.09, -1.54]), and antiapoptotic agents improved behavioral outcomes the most (normalized mean difference: 52.38, CI: [45.29, 59.46]). Statistically significant heterogeneity was observed (I2 = 82 - 98%, all p < 0.001), indicating that studies wildly differ in their effect size estimates. Our results support the superiority of adding cytoprotective therapies with TH (vs. individual or no therapy). Additional exploratory and confirmatory studies are required to identify and thoroughly assess combination therapies owing to limited work and inconsistent translational quality.

Pyruvate Dehydrogenase Complex in Neonatal Hypoxic-Ischemic Brain Injury

The disruption of cerebral energy metabolism in relation to brain damage has been the subject of extensive research. However, the pyruvate dehydrogenase complex (PDHC), which is primarily characterized by poor cerebral energy metabolism following brain trauma, has received relatively little study in comparison to newborn hypoxic-ischemic brain injury. Mitochondrial PDHC, a multienzyme complex that functions as a crucial hub in energy metabolism and acts as a central metabolic node to mediate pyruvate oxidation after glycolysis and fuel the Krebs cycle to meet energy demands, has been reported to be one cause of energy metabolism dysfunction according to recent studies. Here we assess the potential mechanisms of neonatal hypoxic-ischemic brain injury-related brain dysfunction mediated by PDHC and further discuss the neuroprotective effects of therapeutic medicines that target PDHC activation. We also provide a summary of recent research on medicines that target PDHC in neonates with hypoxic-ischemic brain damage. Through an understanding of the mechanisms by which it is modulated and an investigation of the neuroprotective techniques available to activate brain PDHC and improve neonatal hypoxic-ischemic impairment, our review emphasizes the significance of PDHC impairment in neonatal hypoxic-ischemic brain injury.

Elevated Blood Alcohol Concentration Is Associated with Improved Clinical Outcomes of Intravenous Thrombolysis Treatment in Acute Ischemic Stroke Patients—A Retrospective Study

Background: Intravenous thrombolysis (IVT) improves acute ischemic stroke (AIS) outcomes, but with limited success. In addition, ethanol potentiates the effect of r-tPA in ischemia models. Methods: The effect of acute alcohol consumption on IVT outcomes was investigated in a retrospective cohort study. AIS patients with detectable blood alcohol concentration (BAC) during IVT were included (alcohol group; n = 60). For each case, 3 control subjects who underwent IVT but denied alcohol consumption were matched in terms of age, sex, affected brain area, and stroke severity. Outcomes were determined using the NIHSS at 7 days and the modified Rankin scale (mRS) at 90 days. Results: Patients were younger and had a less severe stroke than in a standard stroke study. Favorable long-term outcomes (mRS 0–2) occurred significantly more frequently in the alcohol group compared to controls (90% vs. 63%, p < 0.001). However, the rates of hemorrhagic transformation were similar. Multiple logistic regression models identified elevated BAC as a significant protective factor against unfavorable short-term (OR: 0.091, 95% CI: 0.036–0.227, p < 0.001) and long-term outcomes (OR: 0.187, 95% CI: 0.066–0.535, p = 0.002). In patients with BAC > 0.2%, significantly lower NIHSS was observed at 3 and 7 days after IVT vs. in those with 0.01–0.2% ethanol levels. Conclusion: Elevated BAC is associated with improved outcomes in IVT-treated AIS without affecting safety.

Modulators of ASIC1a and its potential as a therapeutic target for age-related diseases

Age-related diseases have become more common with the advancing age of the worldwide population. Such diseases involve multiple organs, with tissue degeneration and cellular apoptosis. To date, there is a general lack of effective drugs for treatment of most age-related diseases and there is therefore an urgent need to identify novel drug targets for improved treatment. Acid-sensing ion channel 1a (ASIC1a) is a degenerin/epithelial sodium channel family member, which is activated in an acidic environment to regulate pathophysiological processes such as acidosis, inflammation, hypoxia, and ischemia. A large body of evidence suggests that ASIC1a plays an important role in the development of age-related diseases (e.g., stroke, rheumatoid arthritis, Huntington's disease, and Parkinson's disease.). Herein we present: 1) a review of ASIC1a channel properties, distribution, and physiological function; 2) a summary of the pharmacological properties of ASIC1a; 3) and a consideration of ASIC1a as a potential therapeutic target for treatment of age-related disease.

Clinical factors associated with functional outcomes in patients with single subcortical infarction with neurological deterioration

Objective

Factors that predict poor outcomes in patients with single subcortical infarction (SSI) may differ from those that predict poor outcomes in the SSI subgroup with neurological deterioration (ND). This study aimed to investigate the effect of ND on functional outcomes in patients with SSI and the clinical factors that predict poor outcomes in patients with SSI with ND (SSI-ND) and in all patients with SSI.

Methods

Patients with SSI were consecutively enrolled in this study. ND was defined as an increase of ≥2 points in the National Institutes of Health Stroke Scale (NIHSS) total score, an increase of ≥1 point in the NIHSS subscore of consciousness or motor function, or any new neurological deficit.

Results

A total of 255 patients were enrolled, and nine (3.53%) were lost to a follow-up. ND [adjusted relative risk (aRR) = 1.37, 95% confidence interval (CI) = 1.22-1.55, p < 0.001], female sex (aRR = 1.13, 95% CI = 1.03-1.24, p = 0.12), initial NIHSS (aRR = 1.08, 95% CI = 1.07-1.10, p < 0.001), and parental arterial disease (PAD) (aRR = 1.16, 95% CI = 1.07-1.26, p = 0.038) were associated with a poor 90-day outcome (the modified Rankin scale (mRS) > 2 points) in patients with SSI. In the SSI-ND subgroup, PAD (aRR = 2.15, 95% CI = 1.20-3.86, p = 0.01), glycosylated hemoglobin (aRR = 1.17, 95% CI = 1.01-1.35, p = 0.035), and severe NIHSS (aRR = 1.15, 95% CI = 1.06-1.25, p = 0.001) were predictive of a poor outcome, and PAD (aRR = 1.87, 95% CI = 1.19-2.95, p = 0.007) was correlated with higher/worsened NIHSS [> 2 points (median)]. For predicting poor outcomes in patients with SSI-ND with PAD, a more severe NIHSS (aRR = 1.09, 95% CI = 1.02-1.17, p = 0.01) was the only determinant, with a cutoff of 4.5 points, a sensitivity of 94.0%, and a specificity of 83.3%.

Conclusions

ND is an independent predictor of poor outcomes in patients with SSI, and poor outcome determinants in the SSI-ND subgroup and in all patients with SSI are not identical. For patients with SSI-ND, PAD could aggravate ND and was therefore an essential predictor of poor outcomes.

Neuroprotective Effects of Pharmacological Hypothermia on Hyperglycolysis and Gluconeogenesis in Rats after Ischemic Stroke

Stroke is a leading threat to human life. Metabolic dysfunction of glucose may play a key role in stroke pathophysiology. Pharmacological hypothermia (PH) is a potential neuroprotective strategy for stroke, in which the temperature is decreased safely. The present study determined whether neuroprotective PH with chlorpromazine and promethazine (C + P), plus dihydrocapsaicin (DHC) improved glucose metabolism in acute ischemic stroke. A total of 208 adult male Sprague Dawley rats were randomly divided into the following groups: sham, stroke, and stroke with various treatments including C + P, DHC, C + P + DHC, phloretin (glucose transporter (GLUT)-1 inhibitor), cytochalasin B (GLUT-3 inhibitor), TZD (thiazolidinedione, phosphoenolpyruvate carboxykinase (PCK) inhibitor), and apocynin (nicotinamide adenine dinucleotide phosphate oxidase (NOX) inhibitor). Stroke was induced by middle cerebral artery occlusion (MCAO) for 2 h followed by 6 or 24 h of reperfusion. Rectal temperature was monitored before, during, and after PH. Infarct volume and neurological deficits were measured to assess the neuroprotective effects. Reactive oxygen species (ROS), NOX activity, lactate, apoptotic cell death, glucose, and ATP levels were measured. Protein expression of GLUT-1, GLUT-3, phosphofructokinase (PFK), lactate dehydrogenase (LDH), PCK1, PCK2, and NOX subunit gp91 was measured with Western blotting. PH with a combination of C + P and DHC induced faster, longer, and deeper hypothermia, as compared to each alone. PH significantly improved every measured outcome as compared to stroke and monotherapy. PH reduced brain infarction, neurological deficits, protein levels of glycolytic enzymes (GLUT-1, GLUT-3, PFK and LDH), gluconeogenic enzymes (PCK1 and PCK2), NOX activity and its subunit gp91, ROS, apoptotic cell death, glucose, and lactate, while raising ATP levels. In conclusion, stroke impaired glucose metabolism by enhancing hyperglycolysis and gluconeogenesis, which led to ischemic injury, all of which were reversed by PH induced by a combination of C + P and DHC.

Efficacy of melatonin in term neonatal models of perinatal hypoxia-ischaemia

OBJECTIVE

Neonatal encephalopathy (NE) is an important cause of mortality and disability worldwide. Therapeutic hypothermia (HT) is an effective therapy, however not all babies benefit. Novel agents are urgently needed to improve outcomes. Melatonin in preclinical studies has promising neuroprotective properties. This meta-analysis assessed the efficacy of melatonin in term animal models of NE on cerebral infarct size, neurobehavioural tests and cell death.

METHODS

A literature search was carried out using Embase, MEDLINE and Web of Science (31 May 2021). We identified 14 studies and performed a meta-analysis with a random effects model using standardised mean difference (SMD) as the effect size. The risk of bias was assessed using the Systematic Review Centre for Laboratory animal Experimentation tool and publication bias was assessed with funnel plots, and adjusted using trim and fill analysis. Subgroup and meta-regression analyses were performed to assess the effects of study design variables.

RESULTS

We observed significant reduction in brain infarct size (SMD -2.05, 95% CI [-2.93, -1.16]), improved neurobehavioural outcomes (SMD -0.86, 95% CI [-1.23, -0.53]) and reduction in cell death (SMD -0.60, 95% CI [-1.06, -0.14]) favouring treatment with melatonin. Neuroprotection was evident as a single therapy and combined with HT. Subgroup analysis showed greater efficacy with melatonin given before or immediately after injury and with ethanol excipients. The overall effect size remained robust even after adjustment for publication bias.

INTERPRETATION

These studies demonstrate a significant neuroprotective efficacy of melatonin in term neonatal models of hypoxia-ischaemia, and suggest melatonin is a strong candidate for translation to clinical trials in babies with moderate-severe NE.

Alcohol does not increase in-hospital mortality due to severe blunt trauma: an analysis of propensity score matching using the Japan Trauma Data Bank

Aim

Alcohol‐related problems, including trauma, are a great burden on global health. Alcohol metabolism in the Japanese population is genetically inferior to other races. This study aimed to evaluate the effects of alcohol use among a Japanese severe blunt trauma cohort.

Methods

This retrospective observational study analyzed the data of trauma patients registered in the Japan Trauma Data Bank between 2004 and 2019. The primary outcome of this study was in‐hospital mortality. The lengths of hospital and intensive care unit stay were the secondary outcomes. Propensity score matching was used to adjust the anatomical severity and patient background to reduce the potential alcohol use bias.

Results

We analyzed 46,361 patients categorized into nondrinking (n = 37,818) and drinking (n = 8,543) groups. After a 1:1 propensity score matching (n = 8,428, respectively), despite the Glasgow Coma Scale and Revised Trauma Score scores being significantly lower in the drinking group (14 vs. 13 and 7.84 vs. 7.55, P < 0.001, respectively) and intensive care unit length of stay being significantly longer in the drinking group (6 vs. 7 days, P = 0.002), in‐hospital mortality was significantly lower in the alcohol group (11.8% vs. 9.0%, P < 0.001) and there were no differences in the duration of hospital stay (19 vs. 19 days, P = 0.848).

Conclusion

Despite increasing physiological severity on admission, after adjusting for anatomical severity, alcohol consumption could be beneficial in severe blunt trauma patients as regards in‐hospital mortality.

Phosphoenolpyruvate Carboxykinase (PCK) in the Brain Gluconeogenic Pathway Contributes to Oxidative and Lactic Injury After Stroke

To demonstrate the role of the rate-limiting and ATP-dependent gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PCK) in oxidative and lactic stress and the effect of phenothiazine on PCK after stroke, a total of 168 adult male Sprague Dawley rats (3 months old, 280-300 g) underwent 2-h intraluminal middle cerebral artery occlusion (MCAO) and reperfusion for 6, 24, 48 h, or 7 days. Phenothiazine (chlorpromazine and promethazine (C+P)) (8 mg/kg) and 3-mercaptopicolinic acid (3-MPA, a PCK inhibitor, 100 μM) were administered at reperfusion onset. The effects of phosphoenolpyruvate, 3-MPA, or PCK knockdown were studied in neuronal cultures subjected to oxygen/glucose deprivation. Reactive oxygen species, lactate, phosphoenolpyruvate (PEP; a gluconeogenic product), mRNA, and protein of total PCK, PCK-1, and PCK-2 increased after MCAO and oxygen-glucose deprivation (OGD). Oxaloacetate (a gluconeogenic substrate) decreased, while PEP and glucose were increased, suggesting reactive gluconeogenesis. These changes were attenuated by phenothiazine, 3-MPA, or PCK shRNA. PCK-1 and -2 existed primarily in neurons, while the effects of ischemic stroke on the PCK expression were seen predominately in astrocytes. Thus, phenothiazine reduced infarction and oxidative/lactic stress by inhibiting PCKs, leading to functional recovery.

Normobaric oxygen therapy attenuates hyperglycolysis in ischemic stroke

Normobaric oxygen therapy has gained attention as a simple and convenient means of achieving neuroprotection against the pathogenic cascade initiated by acute ischemic stroke. The mechanisms underlying the neuroprotective efficacy of normobaric oxygen therapy, however, have not been fully elucidated. It is hypothesized that cerebral hyperglycolysis is involved in the neuroprotection of normobaric oxygen therapy against ischemic stroke. In this study, Sprague-Dawley rats were subjected to either 2-hour middle cerebral artery occlusion followed by 3- or 24-hour reperfusion or to a permanent middle cerebral artery occlusion event. At 2 hours after the onset of ischemia, all rats received either 95% oxygen normobaric oxygen therapy for 3 hours or room air. Compared with room air, normobaric oxygen therapy significantly reduced the infarct volume, neurological deficits, and reactive oxygen species and increased the production of adenosine triphosphate in ischemic rats. These changes were associated with reduced transcriptional and translational levels of the hyperglycolytic enzymes glucose transporter 1 and 3, phosphofructokinase 1, and lactate dehydrogenase. In addition, normobaric oxygen therapy significantly reduced adenosine monophosphate-activated protein kinase mRNA expression and phosphorylated adenosine monophosphate-activated protein kinase protein expression. These findings suggest that normobaric oxygen therapy can reduce hyperglycolysis through modulating the adenosine monophosphate-activated protein kinase signaling pathway and alleviating oxidative injury, thereby exhibiting neuroprotective effects in ischemic stroke. This study was approved by the Institutional Animal Investigation Committee of Capital Medical University (approval No. AEEI-2018-033) on August 13, 2018.

Modafinil-coated nanoparticle increases expressions of brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor and neuronal nuclear protein, and protects against middle cerebral artery occlusion-induced neuron apoptosis in the rat hippocampus

The present study investigates the neuroprotective effects of modafinil-coated nanoparticle in rats' hippocampal CA1 region. Male Wistar rats (n = 48) were randomly divided into four groups. Then middle cerebral artery occlusion (MCAO) was performed by inserting a silicone coat filament in the right internal carotid artery via the external carotid artery until it reached the anterior cerebral artery. Modafinil (100 mg/kg) or modafinil-coated nanoparticle (100 mg/kg) was given to the rats as an oral gavage once a day. Infarct volume, brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), neuronal nuclear protein (NeuN) and Caspase-3 and, Caspase-8 as apoptotic genes were measured in the hippocampal CA1 region. Cresyl violet staining revealed that modafinil nanoparticle significantly decreased the neurodegeneration. Reverse transcription polymerase chain reaction results showed that modafinil nanoparticle use significantly increased the expression of neurotrophic factors (even more than modafinil alone group; p = .01). Moreover, the apoptotic markers were significantly decreased in nanoparticle modafinil (MN group); p < .05). The western blot analysis and Immunohistochemistry results confirmed the neuroprotective and anti-apoptotic effects of modafinil nanoparticle. This study's results showed that the use of modafinil-coated nanoparticle has neuroprotective effects by increasing neurotrophic factors and reducing apoptosis after MCAO in the CA1 area of the hippocampus. However, further studies are needed especially, in human samples.

Factors and Molecular Mechanisms Influencing the Protein Synthesis, Degradation and Membrane Trafficking of ASIC1a

Acid-sensing ion channels (ASICs) are members of the degenerin/epithelial sodium channel superfamily. They are extracellular pH sensors that are activated by protons. Among all ASICs, ASIC1a is one of the most intensively studied isoforms because of its unique ability to be permeable to Ca²⁺. In addition, it is considered to contribute to various pathophysiological conditions. As a membrane proton receptor, the number of ASIC1a present on the cell surface determines its physiological and pathological functions, and this number partially depends on protein synthesis, degradation, and membrane trafficking processes. Recently, several studies have shown that various factors affect these processes. Therefore, this review elucidated the major factors and underlying molecular mechanisms affecting ASIC1a protein expression and membrane trafficking.

High-Dose Melatonin and Ethanol Excipient Combined with Therapeutic Hypothermia in a Newborn Piglet Asphyxia Model

With the current practice of therapeutic hypothermia for neonatal encephalopathy, disability rates and the severity spectrum of cerebral palsy are reduced. Nevertheless, safe and effective adjunct therapies are needed to optimize outcomes. This study's objective was to assess if 18 mg/kg melatonin given rapidly over 2 h at 1 h after hypoxia-ischemia with cooling from 1-13 h was safe, achieved therapeutic levels within 3 h and augmented hypothermic neuroprotection. Following hypoxia-ischemia, 20 newborn piglets were randomized to: (i) Cooling 1-13 h (HT; n = 6); (ii) HT+ 2.5% ethanol vehicle (HT+V; n = 7); (iii) HT + Melatonin (HT+M; n = 7). Intensive care was maintained for 48 h; aEEG was acquired throughout, brain MRS acquired at 24 and 48 h and cell death (TUNEL) evaluated at 48 h. There were no differences for insult severity. Core temperature was higher in HT group for first hour after HI. Comparing HT+M to HT, aEEG scores recovered more quickly by 19 h (p < 0.05); comparing HT+V to HT, aEEG recovered from 31 h (p < 0.05). Brain phosphocreatine/inorganic phosphate and NTP/exchangeable phosphate were higher at 48 h in HT+M versus HT (p = 0.036, p = 0.049 respectively). Including both 24 h and 48 h measurements, the rise in Lactate/N-acetyl aspartate was reduced in white (p = 0.030) and grey matter (p = 0.038) after HI. Reduced overall TUNEL positive cells were observed in HT+M (47.1 cells/mm²) compared to HT (123.8 cells/mm²) (p = 0.0003) and HT+V (97.5 cells/mm²) compared to HT (p = 0.012). Localized protection was seen in white matter for HT+M versus HT (p = 0.036) and internal capsule for HT+M compared to HT (p = 0.001) and HT+V versus HT (p = 0.006). Therapeutic melatonin levels (15-30mg/l) were achieved at 2 h and were neuroprotective following HI, but ethanol vehicle was partially protective.

The Effect of Exosomes Derived from Bone Marrow Stem Cells in Combination with Rosuvastatin on Functional Recovery and Neuroprotection in Rats After Ischemic Stroke

Rosuvastatin, known as a cholesterol-lowering agent, has been used as an alternative therapy after the onset of stroke. In this study, neuroprotection and functional recovery of exosomes in combination with rosuvastatin have been investigated. Sixty adult male Wistar rats were subjected to middle cerebral artery occlusion (MCAO). Exosome at the dose of 100 μg and/or rosuvastatin at the dose of 20 mg/kg/day for 7 days were administered to rats as a therapeutic strategy. The elevated body swing test (EBST) and Garcia score were conducted as behavioral tests for the measurement of functional recovery. The histopathological and immunohistochemical analyses were also performed for the assessment of infarcted volume and neuroprotection in the brain of rats. The real-time PCR method was carried out to determine the relative expressions of the NLRP-3 and NLRP1 genes. After 7 days of treatment with exosome and rosuvastatin in rats which underwent MCAO, the decrease in infarct volume of the animals treated with exosome was more pronounced compared with those treated only with exosome. The combination therapy remarkably lowered the size of infarct volume. Our observation was confirmed by the downregulation of the NLRP1 and NLRP3 genes in response to combinatory treatment of rats induced by MCOA, denoting a lower rate of cell death. The number of GFAP-positive cells were reduced in the exosome-treated group compared with the MCAO group. The rate of lipid peroxidation was measured by malondialdehyde (MDA) levels which demonstrated a significant reduction of MDA in the exosome- and rotuvastatin-treated groups when compared with the MCAO group. However, the levels of the SOD enzyme did not significantly alter when the treatment groups were compared with the MCAO group. According to our findings, it seems that the use of exosomes and rosuvastatin, as a novel treatment regimen, might promote neurological recovery after the onset of stroke.

Reduced Apoptotic Injury by Phenothiazine in Ischemic Stroke through the NOX-Akt/PKC Pathway

Phenothiazine treatment has been shown to reduce post-stroke ischemic injury, though the underlying mechanism remains unclear. This study sought to confirm the neuroprotective effects of phenothiazines and to explore the role of the NOX (nicotinamide adenine dinucleotide phosphate oxidase)/Akt/PKC (protein kinase C) pathway in cerebral apoptosis. Sprague-Dawley rats underwent middle cerebral artery occlusion (MCAO) for 2 h and were randomly divided into 3 different cohorts: (1) saline, (2) 8 mg/kg chlorpromazine and promethazine (C+P), and (3) 8 mg/kg C+P as well as apocynin (NOX inhibitor). Brain infarct volumes were examined, and cell death/NOX activity was determined by assays. Western blotting was used to assess protein expression of kinase C-δ (PKC-δ), phosphorylated Akt (p-Akt), Bax, Bcl-XL, and uncleaved/cleaved caspase-3. Both C+P and C+P/NOX inhibitor administration yielded a significant reduction in infarct volumes and cell death, while the C+P/NOX inhibitor did not confer further reduction. In both treatment groups, anti-apoptotic Bcl-XL protein expression generally increased, while pro-apoptotic Bax and caspase-3 proteins generally decreased. PKC protein expression was decreased in both treatment groups, demonstrating a further decrease by C+P/NOX inhibitor at 6 and 24 h of reperfusion. The present study confirms C+P-mediated neuroprotection and suggests that the NOX/Akt/PKC pathway is a potential target for efficacious therapy following ischemic stroke.

Artificial Hibernation by Phenothiazines: A Potential Neuroprotective Therapy Against Cerebral Inflammation in Stroke

Background:

The inflammatory response to acute cerebral ischemia is a major factor in stroke pathobiology and patient outcome. In the clinical setting, no effective pharmacologic treatments are currently available. Phenothiazine drugs, such as chlorpromazine and promethazine, (C+P) have been widely studied because of their ability to induce neuroprotection through artificial hibernation after stroke. The present study determined their effect on the inflammatory response.

Methods:

Sprague-Dawley rats were divided into 4 groups: (1) sham, (2) stroke, (3) stroke treated by C+P without temperature control and (4) stroke treated by C+P with temperature control (n=8 per group). To assess the neuroprotective effect of C+P, brain damage was measured using infarct volume and neurological deficits. The expression of inflammatory response molecules tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), and nuclear factor kappa light chain enhancer of activated B cells (NF-κB) was determined by real-time PCR and Western blotting

Results:

TNF-α, IL-1β, ICAM-1, VCAM-1, and NF-κB mRNA and protein expressions were upregulated, and brain damage and neurological deficits were increased after stroke. These markers of cerebral injury were significantly reduced following C+P administration under drug-induced hypothermia, while C+P administration under normal body temperature reduced them by a lesser degree.

Conclusion:

This study showed an inhibitory effect of C+P on brain inflammation, which may be partially dependent on drug-induced hibernation, as well as other mechanisms of action by these drugs. These findings further suggest the great potential of C+P in the clinical treatment of ischemic stroke.

Does alcohol play the role of confounder or neuroprotective agent in acute carbon monoxide poisoning?

Objectives: This study investigated whether alcohol influences the predictive value of initial blood lactate concentration and Glasgow Coma Scale (GCS) score at presentation for the severity of acute carbon monoxide (CO) poisoning and neurologic outcome in patients with acute CO poisoning. Additionally, whether alcohol has a neuroprotective effect after acute CO poisoning was evaluated.Methods: This retrospective study included 158 patients who presented with acute CO poisoning between January 2017 and July 2018 and had an available blood alcohol content (BAC) at presentation. The baseline characteristics, clinical course during hospitalization and neurologic status at 30 days after acute CO poisoning were collected and compared according to BAC. To account for possible confounding or neuroprotective effects of alcohol, BAC was introduced as a continuous variable and a stratified categorical variable in the analysis.Results: The mean and maximum BAC at presentation were 56.8 mg/dl and 408 mg/dl, respectively, in 158 patients presented at a mean of 1.0 hour after acute CO poisoning. Lactate, adjusted for previously suggested predictors, was not associated with acute CO poisoning severity; however, after additional adjustment with BAC variables, lactate was associated with CO poisoning severity. Initial GCS score was associated with CO poisoning severity during hospitalization and neurologic outcome at 30 days after acute CO poisoning, regardless of BAC adjustment. BAC variables were negatively associated with CO poisoning severity but not neurologic outcome at 30 days.Discussion and conclusion: The severity of CO poisoning should never be predicted based on serum lactate alone without adjusting for BAC. However, the initial GCS score can be used as a predictor of CO poisoning severity and the neurologic outcome at 30 days after acute CO poisoning, regardless of alcohol consumption history. Alcohol does not have a neuroprotective effect on acute CO poisoning. Further study is needed to validate these results.

Neuroprotective effect of ethanol and Modafinil on focal cerebral ischemia in rats

Ethanol is known as an effective agent against cerebral lesions after ischemia. Modafinil is a stimulant of the central nervous system (CNS) with antioxidant properties. We assessed the neuroprotective effect of modafinil in combination with ethanol after focal cerebral ischemia. Male wistar rats weighing 280-300 g were divided into nine groups (n = 12 each group): The groups consisted of the MCAO (middle cerebral artery occlusion) group (i.e. ischemia without treatment); the vehicle group(Dimethylsulfoxide); the modafinil group including three subgroups which pretreated with Modafinil (10, 30, 100 mg/kg), respectively, for seven days prior to the induction of MCAO; the ethanol group which received 1.5g/kg ethanol at the time of reperfusion; and modafinil+ethanol group which was divided into three subgroups that received three doses of modanifil (10, 30,100 mg/kg), respectively, for seven days prior to MCAO as well as ethanol at the time of reperfusion. Transient cerebral ischemia was induced by 60-min intraluminal occlusion of the right middle cerebral artery. Edema, infarct volume, glial scar formation (gliosis) and apoptosis were analyzed. The ethanol alone treatment (with a less significant effect), modafinil (in a dose-dependent way), and the combination of modafinil and ethanol significantly decreased the brain infarct volume, edema, apoptosis, and gliosis (P ≤ 0.05). Additionally, modafinil+ethanol mediated the restoration of aerobic metabolism and hyper-glycolysis suppress, thereby resulting in an increase in pyruvate dehydrogenase and a decrease in lactate dehydrogenase activity, respectively, which ultimately reduced oxidative reperfusion injury. These results demonstrate that pretreatment with modafinil (100 mg/kg) and modafinil+ethanol(1.5 g/kg) may prevent ischemic brain injuries.

Therapeutic Target and Cell-signal Communication of Chlorpromazine and Promethazine in Attenuating Blood-Brain Barrier Disruption after Ischemic Stroke

Ischemic stroke destroys blood-brain barrier (BBB) integrity. There are currently no effective treatments available in the clinical setting. Post-ischemia treatment with phenothiazine drugs [combined chlorpromazine and promethazine (C+P)] has been shown to be neuroprotective in stroke. The present study determined the effect of C+P in BBB integrity. Sprague-Dawley rats were divided into the following groups ( n=8 each): (1) stroke, (2) stroke treated by C+P with temperature control, and (3) stroke treated by C+P without temperature control. Infarct volume and neurological deficits were measured to assess the neuroprotective effect of C+P. BBB permeability was determined by brain edema and Evans blue leakage. Expression of BBB integral molecules, including proteins of aquaporin-4 and -9 (AQP-4, AQP-9), matrix metalloproteinase-2 and -9 (MMP-2, MMP-9), zonula occludens-1 (ZO-1), claudin-1/5, occludin, and laminin were determined by Western blot. Stroke caused brain infarction and neurological deficits, as well as BBB damage, which were all attenuated by C+P through drug-induced hypothermia. When the reduced temperature was controlled to physiological levels, C+P still conferred neuroprotection, suggesting a therapeutic effect independent of hypothermia. Furthermore, C+P significantly attenuated the increase in AQP-4, AQP-9, MMP-2, and MMP-9 levels after stroke, and reversed the decrease in tight junction protein (ZO-1, claudin-1/5, occludin) and basal laminar protein (laminin) levels. This study clearly indicates a beneficial effect of C+P on BBB integrity after stroke, which may be independent of drug-induced hypothermia. These findings further prove the clinical target and cell-signal communication of C+P treatment, which may direct us closer toward the development of an efficacious neuroprotective therapy.

Role of HIF-1α in Alcohol-Mediated Multiple Organ Dysfunction

Excess alcohol consumption is a global crisis contributing to over 3 million alcohol-related deaths per year worldwide and economic costs exceeding $200 billion dollars, which include productivity losses, healthcare, and other effects (e.g., property damages). Both clinical and experimental models have shown that excessive alcohol consumption results in multiple organ injury. Although alcohol metabolism occurs primarily in the liver, alcohol exposure can lead to pathophysiological conditions in multiple organs and tissues, including the brain, lungs, adipose, liver, and intestines. Understanding the mechanisms by which alcohol-mediated organ dysfunction occurs could help to identify new therapeutic approaches to mitigate the detrimental effects of alcohol misuse. Hypoxia-inducible factor (HIF)-1 is a transcription factor comprised of HIF-1α and HIF-1β subunits that play a critical role in alcohol-mediated organ dysfunction. This review provides a comprehensive analysis of recent studies examining the relationship between HIF-1α and alcohol consumption as it relates to multiple organ injury and potential therapies to mitigate alcohol’s effects.

Melatonin as an adjunct to therapeutic hypothermia in a piglet model of neonatal encephalopathy: A translational study

Therapeutic hypothermia is only partially protective for neonatal encephalopathy; there is an urgent need to develop treatments that augment cooling. Our objective was to assess safety, efficacy and pharmacokinetics of 5 and 15 mg/kg/24 h melatonin (proprietary formulation) administered at 2 h and 26 h after hypoxia-ischemia (HI) with cooling in a piglet model. Following moderate cerebral HI, 30 piglets were eligible and randomized to: i) Hypothermia (33.5 °C, 2-26 h) and vehicle (HT + V;n = 13); b) HT and 5 mg/kg melatonin over 6 h at 2 h and 26 h after HI (HT + Mel-5;n = 4); c) HT and 15 mg/kg melatonin over 6 h at 2 h and 26 h after HI (HT + Mel-15;n = 13). Intensive care was maintained for 48 h; brain MRS was acquired and cell death (TUNEL) evaluated at 48 h. Comparing HT + V with HT + Mel-5 and HT + Mel-15, there was no difference in blood pressure or inotropic support needed, brain Lactate/N Acetylaspartate at 24 h and 48 h was similar, ATP/phosphate pool was higher for HT + Mel-15 versus HT + V at 24 h (p = 0.038) but not 48 h. A localized reduction in TUNEL positive cell death was observed in the sensorimotor cortex in the 15 mg/kg melatonin group (HT + Mel-15 versus HT + V; p < 0.003) but not in the 5 mg/kg melatonin group (HT + Mel-5 versus HT + V; p = 0.808). Putative therapeutic melatonin levels were reached 8 h after HI (10⁴ increase from baseline; ~15-30 mg/l). Mean ± SD peak plasma melatonin levels after the first infusion were 0.0014 ± 0.0012 mg/l in the HT + V group, 3.97 ± 1.53 mg/l in the HT + Mel-5 group and 16.8 ± 8.3 mg/l in the HT + Mel-15 group. Protection was dose dependent; 15 mg/kg melatonin started 2 h after HI, given over 6 h, was well tolerated and augmented hypothermic protection in sensorimotor cortex. Earlier attainment of therapeutic plasma melatonin levels may optimize protection by targeting initial events of reperfusion injury. The time window for intervention with melatonin, as adjunct therapy with cooling, is likely to be narrow and should be considered in designing future clinical studies.

Morphological and immunohistochemical analysis of proteins CASPASE 3 and XIAP in rats subjected to cerebral ischemia and chronic alcoholism

PURPOSE

To evaluate histopathological and ultrastructural changes and expression of proteins related to apoptosis CASPASE 3 and XIAP after experimental induction of temporary focal cerebral ischemia (90 minutes) due to obstruction of the middle cerebral artery in alcoholism model.

METHODS

Forty adult Wistar rats were used, subdivided into 5 experimental groups: control group (C); Sham group (S); Ischemic group (I); Alcoholic group (A); and Ischemic and Alcoholized group (I+A): animals submitted to the same treatment of group A and after four weeks were submitted to focal cerebral ischemia during 90 minutes, followed by reperfusion of 48 hours. Were processed for histopathological analysis and immunohistochemistry (for the protein expression of CASPASE -3 and XIAP).

RESULTS

Greater histopathological changes were observed in the animals of groups I and I+A in the three areas analyzed. The neuronal loss was higher in the medial striatum region of the animals of groups I and I + A. The protein expression of CASPASE -3 was higher than that of XIAP in the groups I and I + A for both proteins.

CONCLUSION

The expression of XIAP was slightly higher where the histopathological changes and expression of CASPASE -3 was less evident.

Suppression of the interleukin-1ß-induced inflammatory response of human Chang liver cells by acute and subacute exposure to alcohol: an in vitro study

Aim

To evaluate protective immunosuppressive dose and time-dependent effects of ethanol in an in vitro model of acute inflammation in human Chang liver cells.

Method

The study was performed in 2016 and 2017 in the research laboratory of the Department of Trauma, Hand and Reconstructive Surgery, the University Hospital of the Goethe-University Frankfurt. Chang liver cells were stimulated with either interleukin (IL)-1β or IL-6 and subsequently treated with low-dose ethanol (85 mmol/L) or high-dose ethanol (170 mmol/L) for one hour (acute exposure) or 72 hours (subacute exposure). IL-6 and IL-1β release were determined by enzyme-linked immunosorbent assay. Neutrophil adhesion to Chang liver monolayers, production of reactive oxygen species, and apoptosis or necrosis were analyzed.

Results

Contrary to high-dose ethanol, acute low-dose ethanol exposure significantly reduced IL-1β-induced IL-6 and IL-6-induced IL-1β release (P < 0.05). Subacute ethanol exposure did not change proinflammatory cytokine release. Acute low-dose ethanol exposure significantly decreased inflammation-induced formation of reactive oxygen species (P < 0.05) and significantly improved cell survival (P < 0.05). Neither acute nor subacute high-dose ethanol exposure significantly changed inflammation-induced changes in reactive oxygen species or survival. Acute and subacute ethanol exposure, independently of the dose, significantly decreased neutrophil adhesion to inflamed Chang liver cells (P < 0.05).

Conclusion

Acute treatment of inflamed Chang liver cells with ethanol showed its immunosuppressive potential. However, the observed effects were limited to low-dose setting, indicating the relevance of ethanol dose in the modulation of inflammatory cell response.

Acute Ethanol Exposure Promotes Autophagy-Lysosome Pathway-Dependent ASIC1a Protein Degradation and Protects Against Acidosis-Induced Neurotoxicity

Tissue acidosis is a common feature of brain ischemia which causes neuronal injury. Activation of acid-sensing ion channel 1a (ASIC1a) plays an important role in acidosis-mediated neurotoxicity. Acute ethanol administration has been shown to provide neuroprotective effects during ischemic stroke, but the precise mechanisms have yet to be determined. In this study, we investigated the effect of ethanol on the activity/expression of ASIC1a channels and acidosis-induced neurotoxicity. We showed that acute treatment of neuronal cells with ethanol for more than 3 h could reduce ASIC1a protein expression, ASIC currents, and acid-induced [Ca²⁺]_i elevation. We further demonstrated that ethanol-induced reduction of ASIC1a expression is mediated by autophagy-lysosome pathway (ALP)-dependent protein degradation. Finally, we showed that ethanol protected neuronal cells against acidosis-induced cytotoxicity, which effect was mimicked by autophagy activator rapamycin and abolished by autophagy inhibitor CQ. Together, these results indicate that moderate acute ethanol exposure can promote autophagy-lysosome pathway-dependent ASIC1a protein degradation and protect against acidosis-induced neurotoxicity.

Synergistically Induced Hypothermia and Enhanced Neuroprotection by Pharmacological and Physical Approaches in Stroke

Hypothermia is considered as a promising neuroprotective treatment for ischemic stroke but with many limitations. To expand its clinical relevance, this study evaluated the combination of physical (ice pad) and pharmacological [transient receptor potential vanilloid channel 1 (TRPV1) receptor agonist, dihydrocapsaicin (DHC)] approaches for faster cooling and stronger neuroprotection. A total of 144 male Sprague Dawley rats were randomized to 7 groups: sham (n=16), stroke only (n=24), stroke with physical hypothermia at 31ºC for 3 h after the onset of reperfusion (n=24), high-dose DHC (H-DHC)(1.5 mg/kg, n=24), low-dose DHC (L-DHC)(0.5 mg/kg, n=32) with (n=8) or without (n=24) external body temperature control at ~38 ºC (L-DHC, 38 ºC), and combination therapy (L-DHC+ ice pad, n=24). Rats were subjected to middle cerebral artery occlusion (MCAO) for 2 h. Infarct volume, neurological deficits and apoptotic cell death were determined at 24 h after reperfusion. Expression of pro- and anti-apoptotic proteins was evaluated by Western blot. ATP and reactive oxygen species (ROS) were detected by biochemical assays at 6 and 24 h after reperfusion. Combination therapy of L-DHC and ice pad significantly improved every measured outcome compared to monotherapies. Combination therapy achieved hypothermia faster by 28.6% than ice pad, 350% than L-DHC and 200% than H-DHC alone. Combination therapy reduced (p<0.05) neurological deficits by 63% vs. 26% with L-DHC. No effect was observed when using ice pad or H-DHC alone. L-DHC and ice pad combination improved brain oxidative metabolism by reducing (p<0.05) ROS at 6 and 24 h after reperfusion and increasing ATP levels by 42.9% compared to 25% elevation with L-DHC alone. Finally, combination therapy decreased apoptotic cell death by 48.5% vs. 24.9% with L-DHC, associated with increased anti-apoptotic protein and reduced pro-apoptotic protein levels (p<0.001). Our study has demonstrated that combining physical and pharmacological hypothermia is a promising therapeutic approach in ischemic stroke, and warrants further translational investigations.

Exacerbation of Brain Injury by Post-Stroke Exercise Is Contingent Upon Exercise Initiation Timing

Accumulating evidence has demonstrated that post-stroke physical rehabilitation may reduce morbidity. The effectiveness of post-stroke exercise, however, appears to be contingent upon exercise initiation. This study assessed the hypothesis that very early exercise exacerbates brain injury, induces reactive oxygen species (ROS) generation, and promotes energy failure. A total of 230 adult male Sprague-Dawley rats were subjected to middle cerebral artery (MCA) occlusion for 2 h, and randomized into eight groups, including two sham injury control groups, three non-exercise and three exercise groups. Exercise was initiated after 6 h, 24 h and 3 days of reperfusion. Twenty-four hours after completion of exercise (and at corresponding time points in non-exercise controls), infarct volumes and apoptotic cell death were examined. Early brain oxidative metabolism was quantified by examining ROS, ATP and NADH levels 0.5 h after completion of exercise. Furthermore, protein expressions of angiogenic growth factors were measured in order to determine whether post-stroke angiogenesis played a role in rehabilitation. As expected, ischemic stroke resulted in brain infarction, apoptotic cell death and ROS generation, and diminished NADH and ATP production. Infarct volumes and apoptotic cell death were enhanced (p < 0.05) by exercise that was initiated after 6 h of reperfusion, but decreased by late exercise (24 h, 3 days). This exacerbated brain injury at 6 h was associated with increased ROS levels (p < 0.05), and decreased (p < 0.05) NADH and ATP levels. In conclusion, very early exercise aggravated brain damage, and early exercise-induced energy failure with ROS generation may underlie the exacerbation of brain injury. These results shed light on the manner in which exercise initiation timing may affect post-stroke rehabilitation.

Hibernation-like neuroprotection in stroke by attenuating brain metabolic dysfunction

Many mammalian species naturally undergo hibernation, a process that is associated with drastic changes in metabolism and systemic physiology. Their ability to retain an undamaged central nervous system during severely reduced cerebral blood flow has been studied for possible therapeutic application in human ischemic stroke. By inducing a less extreme 'hibernation-like' state, it has been hypothesized that similar neuroprotective effects reduce ischemia-mediated tissue damage in stroke patients. This manuscript includes reviews and evaluations of: (1) true hibernation, (2) hibernation-like state and its neuroprotective characteristics, (3) the preclinical and clinical methods for induction of artificial hibernation (i.e., therapeutic hypothermia, phenothiazine drugs, and ethanol), and (4) the mechanisms by which cerebral ischemia leads to tissue damage and how the above-mentioned induction methods function to inhibit those processes.

Combining Normobaric Oxygen with Ethanol or Hypothermia Prevents Brain Damage from Thromboembolic Stroke via PKC-Akt-NOX Modulation

In a thromboembolic stroke model after reperfusion by recombinant tissue plasminogen activator (rt-PA), we aimed to determine whether therapeutic hypothermia (TH) and ethanol (EtOH) in combination with low concentration (60 %) of normobaric oxygen (NBO) enhanced neuroprotection, as compared to using each of these agents alone. We further aimed to elucidate a potential role of the NADPH oxidase (NOX), phosphorylated protein kinase B (Akt), and protein kinase C-δ (PKC-δ) pathway in oxidative stress and neuroprotection. In Sprague-Dawley rats, a focal middle cerebral artery (MCA) occlusion was induced by an autologous embolus in the following experimental groups: rt-PA treatment alone, rt-PA + NBO treatment, rt-PA + TH at 33 °C, rt-PA + EtOH, rt-PA + NBO + EtOH, rt-PA + NBO + TH, rt-PA + NOX inhibitor, rt-PA + EtOH + NOX inhibitor, or rt-PA + EtOH + Akt inhibitor. Control groups included sham-operated without stroke or stroke without treatment. Infarct volume and neurological deficit were assessed at 24 h after rt-PA-induced reperfusion with or without treatments. ROS levels, NOX activity, and the protein expression of NOX subunits p22phox, p47phox, p67phox, gp91phox, as well as PKC-δ and phosphorylated Akt were measured at 3 and 24 h after rt-PA-induced reperfusion. Following rt-PA in thromboembolic stroke rats, NBO combined with TH or EtOH more effectively decreased infarct volume and neurological deficit, as well as reactive oxygen species (ROS) production than with any of the used monotherapies. NOX activity and subunit expressions were downregulated and temporally associated with reduced PKC-δ and increased p-Akt expression. The present study demonstrated that combining NBO with either TH or EtOH conferred similar neuroprotection via modulation of NOX activation. The results suggest a role of Akt in NOX activation and implicate an upstream PKC-δ pathway in the Akt regulation of NOX. It is possible to substitute EtOH for TH, thus circumventing the difficulties in clinical application of TH through the comparatively easier usage of EtOH as a potential stroke management.

TAT-PEP Enhanced Neurobehavioral Functional Recovery by Facilitating Axonal Regeneration and Corticospinal Tract Projection After Stroke

Paired immunoglobulin-like receptor B (PirB) has been identified as a new receptor for myelin-associated inhibitory (MAI) proteins, which may play important role in axonal regeneration and corticospinal tract (CST) projection associated with neurobehavioral function recovery after stroke. Here, we found that the expression of PirB was increased in the cortical penumbra from 1 to 28 days after transient focal cerebral ischemic reperfusion of rats. Then, transactivator of transcription-PirB extracellular peptide (TAT-PEP) was generated that might block the interactions between MAIs and PirB. The results showed that TAT-PEP displayed high affinity for MAIs and ameliorated their inhibitory effect on neurite growth. Furthermore, TAT-PEP can widely distribute in the penumbra after intraperitoneal injection. Then, we found that TAT-PEP enhanced neurite growth and alleviated growth cone collapse after oxygen glucose deprivation (OGD) injury. In addition, TAT-PEP promoted long-term neurobehavioral functional recovery through enhancing axonal regeneration and CST projection. Finally, the observations demonstrated that POSH/RhoA/growth-associated protein 43 (GAP43) as PirB-associated downstream signaling molecules played important role in neurobehavioral functional recovery after stroke. Moreover, the underlying mechanism associated with TAT-PEP-mediated promoting axonal regeneration and CST projection was by intervening in the expression of POSH, RhoA, and GAP43. These studies suggest that TAT-PEP may represent an attractive therapeutic strategy against stroke.

Early rehabilitation aggravates brain damage after stroke via enhanced activation of nicotinamide adenine dinucleotide phosphate oxidase (NOX)

INTRODUCTION

Although physical exercise has emerged as a potential therapeutic modality for functional deficits following ischemic stroke, the extent of this effect appears to be contingent upon the time of exercise initiation. In the present study, we assessed how exercise timing affected brain damage through hyperglycolysis-associated NADPH oxidase (NOX) activation.

METHODS

Using an intraluminal filament, adult male Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 2h and assigned to one non-exercise and three exercise groups. Exercise on Rota-rod was initiated for 30min at 6h (considered very early), at 24h (early), and at day 3 (relatively late) after reperfusion. Lactate production was measured 30min after exercise completion, and NOX activity and protein expression of NOX subunits (p47(phox), gp91(phox), p22(phox) and p67(phox)) and glucose transporter 1 and 3 (Glut-1 and -3) were measured at 3 and 24h after exercise. Apoptotic cell death was determined at 24h after exercise.

RESULTS

Lactate production and Glut-1 and Glut-3 expression were increased after very early exercise (6h), but not after late exercise (3 days), suggesting hyperglycolysis. NOX activity was increased with the initiation of exercise at 6h (P<0.05), but not 24h or 3 days, following stroke. Early (6 and 24h), but not late (3 days), post-stroke exercise was associated with increased (P<0.05) expression of the NOX protein subunit p47(phox), gp91(phox)and p67(phox). This may have led to the enhanced apoptosis observed after early exercise in ischemic rats.

CONCLUSION

Hyperglycolysis and NOX activation was associated with an elevation in apoptotic cell death after very early exercise, and the detrimental effect of exercise on stroke recovery began to decrease when exercise was initiated 24h after reperfusion.

Enhanced apoptosis from early physical exercise rehabilitation following ischemic stroke

The effectiveness of the rehabilitative benefits of physical exercise appears to be contingent upon when the exercise is initiated after stroke. The present study assessed the hypothesis that very early exercise increases the extent of apoptotic cell death via increased expression of proapoptotic proteins in a rat stroke model. Adult male Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 2 hr using an intraluminal filament and assigned to four nonexercise and three exercise groups. Exercise on a Rota-Rod was initiated for 30 min at 6 hr (considered very early), at 24 hr (early), and at 3 days (relatively late) after reperfusion. At 24 hr after exercise, apoptotic cell death was determined. At 3 and 24 hr after exercise, the expression of pro- and antiapoptotic proteins was evaluated through Western blotting. As expected, ischemic stroke significantly increased the levels of apoptotic cell death. Compared with the stroke group without exercise, apoptotic cell death was further increased (P < 0.05) at 6 hr but not at 24 hr or 3 days with exercise. This exacerbated cell injury was associated with increased expression of proapoptotic proteins (BAX and caspase-3). The expression of Bcl-2, an antiapoptotic protein, was not affected by exercise. In ischemic stroke, apoptotic cell death was enhanced by very early exercise in association with increased expression of proapoptotic proteins. These results shed light on the time-sensitive effect of exercise in poststroke rehabilitation. © 2016 Wiley Periodicals, Inc.

Pyruvate dehydrogenase complex in cerebral ischemia-reperfusion injury

Pyruvate dehydrogenase (PDH) complex is a mitochondrial matrix enzyme that serves a critical role in the conversion of anaerobic to aerobic cerebral energy. The regulatory complexity of PDH, coupled with its significant influence in brain metabolism, underscores its susceptibility to, and significance in, ischemia-reperfusion injury. Here, we evaluate proposed mechanisms of PDH-mediated neurodysfunction in stroke, including oxidative stress, altered regulatory enzymatic control, and loss of PDH activity. We also describe the neuroprotective influence of antioxidants, dichloroacetate, acetyl-L-carnitine, and combined therapy with ethanol and normobaric oxygen, explained in relation to PDH modulation. Our review highlights the significance of PDH impairment in stroke injury through an understanding of the mechanisms by which it is modulated, as well as an exploration of neuroprotective strategies available to limit its impairment.

Cocktail treatment, a promising strategy to treat acute cerebral ischemic stroke?

Up to now, over 1,000 experimental treatments found in cells and rodents have been difficult to translate to human ischemic stroke. Since ischemia and reperfusion, two separate stages of ischemic stroke, have different pathophysiological mechanisms leading to brain injury, a combination of protective agents targeting ischemia and reperfusion respectively may obtain substantially better results than a single agent. Normobaric hyperoxia (NBO) has been shown to exhibit neuro- and vaso-protective effects by improving tissue oxygenation when it is given during ischemia, however the effect of NBO would diminish when the duration of ischemia and reperfusion was extended. Therefore, during reperfusion drug treatment targeting inflammation, oxidative stress and free radical scavenger would be a useful adjuvant to extend the therapeutic window of tissue plasminogen activator, the only United States Food and Drug Administration (FDA) approved treatment for acute ischemic stroke. In this review, we discussed the neuro- and vaso-protective effects of NBO and recent finding of combining NBO with other drugs.

Adjuvant therapies using normobaric oxygen with hypothermia or ethanol for reducing hyperglycolysis in thromboembolic cerebral ischemia

BACKGROUND AND PURPOSE

Normobaric oxygen (NBO), ethanol (EtOH), and therapeutic hypothermia (TH) delivered alone or in combination have neuroprotective properties after acute stroke. We used an autologous thromboembolic rat stroke model to assess the additive effects of these treatments for reducing the deleterious effects of hyperglycolysis post-stroke in which reperfusion is induced with recombinant tissue plasminogen activator (rt-PA).

METHODS

Sprague-Dawley rats were subjected to middle cerebral artery (MCA) occlusion with an autologous embolus. One hour after occlusion, rt-PA was administered alone or with NBO (60%), EtOH (1.0 g/kg), TH (33 °C), either singly or in combination. Infarct volume and neurological deficit were assessed at 24h after rt-PA-induced reperfusion with or without other treatments. The extent of hyperglycolysis, as determined by cerebral glucose and lactate levels was evaluated at 3 and 24h after rt-PA administration. At the same time points, expressions of glucose transporter 1 (Glut1), glucose transporter 3 (Glut3), phosphofructokinase1 (PFK-1), and lactate dehydrogenase were (LDH) measured by Western blotting.

RESULTS

Following rt-PA in rats with thromboembolic stroke, NBO combined with TH or EtOH most effectively decreased infarct volume and neurological deficit. As compared to rt-PA alone, EtOH or TH but not NBO monotherapies significantly reduced post-stroke hyperglycolysis. The increased utilization of glucose and production of lactate post-stroke was prevented most effectively when NBO was combined with either EtOH or TH after reperfusion with rt-PA, as shown by the significantly decreased Glut1, Glut3, PFK-1, and LDH levels.

CONCLUSIONS

In a rat thromboembolic stroke model, both EtOH and TH used individually offer neuroprotection after the administration of rt-PA. While NBO monotherapy does not appear to be effective, it significantly potentiates the efficacy of EtOH and TH. The similar neuroprotection and underlying mechanisms pertaining to the attenuation of hyperglycolysis provided by EtOH or TH in combination with NBO suggest a possibility of substituting EtOH for TH. Thus a combination of NBO and EtOH, which are widely available and easily used, could become a novel and effective neuroprotective strategy in the clinical setting.

Therapeutic effect of tPA in ischemic stroke is enhanced by its combination with normobaric oxygen and hypothermia or ethanol

BACKGROUND AND PURPOSE

Our lab has previously elucidated the neuroprotective effects of normobaric oxygen (NBO) and ethanol (EtOH) in ischemic stroke. The present study further evaluated the effect of EtOH or hypothermia (Hypo) in the presence of low concentration of NBO and determined whether EtOH can substitute hypothermia in a more clinically relevant autologous embolus rat stroke model in which reperfusion was established by tissue-type plasminogen activator (t-PA).

METHODS

At 1h of middle cerebral artery occlusion (MCAO) by an autologous embolus, rats received t-PA. In addition, at the same time, ischemic animals were treated with either EtOH (1.0 g/kg) or hypothermia (33°C for 3h) in combination with NBO (60% for 3h). Extent of neuroprotection was assessed by apoptotic cell death measured by ELISA and Western immunoblotting analysis for pro- (AIF, activated Caspase-3, Bax) and anti-apoptotic (Bcl-2) protein expression at 3 and 24h of reperfusion induced by t-PA administration.

RESULTS

Compared to ischemic rats treated only with t-PA, animals with NBO, hypothermia or EtOH had significantly reduced apoptotic cell death by 32.5%, 43.1% and 36.0% respectively. Furthermore, combination therapy that included NBO+EtOH or NBO+Hypo with t-PA exhibited a much larger decline (p<0.01) in the cell death by 71.1% and 73.6%, respectively. Similarly, NBO+EtOH or NBO+Hypo treatment in addition to t-PA enhanced beneficial effects on both pro- and anti-apoptotic protein expressions as compared to other options.

CONCLUSIONS

Neuroprotection after stroke can be enhanced by combination treatment with either EtOH or hypothermia in the presence of t-PA and 60% NBO. Because the effects produced by EtOH and hypothermia are comparable, their mechanism of action may be not only similar but also could be interchangeable in future clinical trials.

IV thrombolysis in patients with ischemic stroke and alcohol abuse

OBJECTIVE

To determine whether chronic alcohol consumption or acute alcohol intoxication affects the rate of IV thrombolysis (IVT) and associated risk of symptomatic intracranial hemorrhage (SICH) in patients with acute ischemic stroke (IS).

METHODS

We analyzed data from the nationwide Austrian Stroke Unit Registry for all patients with IS admitted to one of 35 stroke units between 2004 and 2014. We compared demographic and clinical characteristics for patients with chronic alcohol consumption (>2 drinks/d) or acute intoxication and for patients without these factors and their rates of IVT and associated SICH.

RESULTS

We identified 47,422 patients with IS. Of these patients, 3,999 (8.5%) consumed alcohol chronically and 216 (0.5%) presented with acute intoxication. Alcohol abusers were younger, more frequently men, and less often functionally disabled before the index event. Stroke severity was comparable between alcoholic and nonalcoholic IS patients. Nevertheless, patients who abused alcohol were less likely to receive IVT (16.6% vs 18.9%) and this difference remained after accounting for possible confounders. Rates of SICH after IVT were not increased in patients who abused alcohol (2.1% vs 3.7%, p = 0.04). Multivariate analysis including age, NIH Stroke Scale score, and time from symptom onset to IVT treatment showed that alcohol abuse was not an independent risk factor for SICH and was not protective (odds ratio 0.73, 95% confidence interval 0.43-1.25, p = 0.2).

CONCLUSIONS

IS patients with chronic alcohol consumption or acute intoxication have decreased likelihood of receiving IVT and are not at an increased risk of associated SICH. This supports current practice guidelines, which do not list chronic alcohol consumption or acute intoxication as an exclusion criterion.

Isoflurane preconditioning provides neuroprotection against stroke by regulating the expression of the TLR4 signalling pathway to alleviate microglial activation

Excessive microglial activation often contributes to inflammation-mediated neurotoxicity in the ischemic penumbra during the acute stage of ischemic stroke. Toll-like receptor 4 (TLR4) has been reported to induce microglial activation via the NF-κB pathway. Isoflurane preconditioning (IP) can provide neuroprotection and inhibit microglial activation. In this study, we investigated the roles of the TLR4 signalling pathway in IP to exert neuroprotection following ischemic stroke in vivo and in vitro. The results showed that 2% IP alleviated neurological deficits, reduced the infarct volume, attenuated apoptosis and weakened microglial activation in the ischemic penumbra. Furthermore, IP down-regulated the expression of HSP 60, TLR4 and MyD88 and up-regulated inhibitor of IκB-α expression compared with I/R group in vivo. In vitro, 2% IP and a specific inhibitor of TLR4, CLI-095, down-regulated the expression of TLR4, MyD88, IL-1β, TNF-α and Bax, and up-regulated IκB-α and Bcl-2 expression compared with OGD group. Moreover, IP and CLI-095 attenuated microglial activation-induced neuronal apoptosis, and overexpression of the TLR4 gene reversed the neuroprotective effects of IP. In conclusion, IP provided neuroprotection by regulating TLR4 expression directly, alleviating microglial activation and neuroinflammation. Thus, inhibiting the activation of microglial activation via TLR4 may be a new avenue for stroke treatment.

Reduced cerebral monocarboxylate transporters and lactate levels by ethanol and normobaric oxygen therapy in severe transient and permanent ischemic stroke

OBJECTIVES

Neuroprotective benefits of ethanol (EtOH) and normobaric oxygenation (NBO) were previously demonstrated in transient and permanent ischemic stroke. Here we sought to identify whether the enhanced lactic acidosis and increased expression of monocarboxylate transporters (MCTs) observed after stroke might be attenuated by single and/or combined EtOH and NBO therapies.

METHODS

Sprague-Dawley rats (n=96) were subjected to right middle cerebral artery occlusion (MCAO) for 2 or 4h (transient ischemia), or 28 h (permanent ischemia) followed by 3, 24h, or no reperfusion. Rats received: (1) either an intraperitoneal injection of saline (sham treatment), one dose of EtOH (1.5 g/kg), two doses of EtOH (1.5 g/kg at 2h of MCAO, followed by 1.0 g/kg 2h after 1st dose), or (2) EtOH+95% NBO (at 2h of MCAO for 6h in permanent ischemia). Lactate levels were detected at 3 and 24h of reperfusion. Gene and protein expressions of MCT-1, -2, -4 were assessed by real-time PCR and western blotting.

RESULTS

A dose-dependent EtOH neuroprotection was found in transient ischemia. Following transient ischemia, a single dose of EtOH (in 2h-MCAO) or a double dose (in 4h-MCAO), significantly attenuated lactate levels, as well as the mRNAs and protein expressions of MCT-1, MCT-2, and MCT-4. However, while two doses of EtOH alone was ineffective in permanent stroke, the combined therapy (EtOH+95% NBO) resulted in a more significant attenuation in all the above levels and expressions.

CONCLUSIONS

Our study demonstrates that acute EtOH administration attenuated lactic acidosis in transient or permanent ischemic stroke. This EtOH-induced beneficial effect was potentiated by NBO therapy in permanent ischemia. Because both EtOH and NBO are readily available, inexpensive and easy to administer, their combination could be implemented in the clinics shortly after stroke.

Weight loss: indication of brain damage and effect of combined normobaric oxygen and ethanol therapy after stroke

BACKGROUND AND PURPOSE

Weight loss is commonly seen after stroke. However, there is paucity of data that objectively examines the relationship between weight loss and infarction. We have used two unique models of middle cerebral artery (MCA) occlusion in rats to determine if weight loss can be used as indicator for severity of brain damage and for beneficial effects of stroke therapy.

METHODS

Sprague-Dawley rats underwent MCA occlusion using the rat intraluminal filament or auto-thrombus stroke models. Reperfusion was established at different intervals by removing the intraluminal filament or injecting r-tPA, followed by treatment with either ethanol (EtOH), normobaric oxygen (NBO), NBO plus EtOH or no treatment. The extent of brain injury was determined using infarct volume and motor performance.

RESULTS

The intraluminal filament ischaemic model demonstrated a significant positive correlation between weight loss and infarct volume size after acute stroke, as well as compared to infarct volumes post-treatment with NBO, EtOH and NBO plus EtOH. There was also a positive significant correlation between weight loss and infarct volume size in the thromboembolism ischaemic model with or without treatment. Furthermore a positive correlation was observed between weight loss and deficit score in both ischaemic models.

DISCUSSION

Degree of weight loss after stroke is largely associated with severity of infarction as well as damage reduction after treatment administration.