Therapeutic Hypothermia Improves Hind Limb Motor Outcome and Attenuates Oxidative Stress and Neuronal Damage in the Lumbar Spinal Cord Following Cardiac Arrest

Differential Effects of Targeted Temperature Management on Sex-Dependent Outcomes After Experimental Asphyxial Cardiac Arrest

Asphyxial cardiac arrest (ACA) survivors face lasting neurological disability from hypoxic ischemic brain injury. Sex differences in long-term outcomes after cardiac arrest (CA) are grossly understudied and underreported. We used rigorous targeted temperature management (TTM) to understand its influence on survival and lasting sex-specific neurological and neuropathological outcomes in a rodent ACA model. Adult male and female rats underwent either sham or 5-minute no-flow ACA with 18 hours TTM at either ∼37°C (normothermia) or ∼36°C (mild hypothermia). Survival, temperature, and body weight (BW) were recorded over the 14-day study duration. All rats underwent neurological deficit score (NDS) assessment on days 1-3 and day 14. Hippocampal pathology was assessed for cell death, degenerating neurons, and microglia on day 14. Although ACA females were less likely to achieve return of spontaneous circulation (ROSC), post-ROSC physiology and biochemical profiles were similar between sexes. ACA females had significantly greater 14-day survival, NDS, and BW recovery than ACA males at normothermia (56% vs. 29%). TTM at 36°C versus 37°C improved 14-day survival in males, producing similar survival in male (63%) versus female (50%). There were no sex or temperature effects on CA1 histopathology. We conclude that at normothermic conditions, sex differences favoring females were observed after ACA in survival, NDS, and BW recovery. We achieved a clinically relevant ACA model using TTM at 36°C to improve long-term survival. This model can be used to more fully characterize sex differences in long-term outcomes and test novel acute and chronic therapies.

Screening and evaluation of metabolites binding PRAS40 from Erxian decoction used to treat spinal cord injury

Objective: The PRAS40 is an essential inhibitory subunit of the mTORC1 complex, which regulates autophagy. It has been suggested that Erxian Decoction (EXD) could treat spinal cord injury (SCI) via the autophagy pathway. However, the mechanism of whether EXD acts through PRAS40 remains unclear. Methods: With the help of immobilized PRAS40, isothermal titration calorimetry (ITC) and molecular docking, the bioactive metabolites in the EXD were screened. To establish in vitro SCI models, PC12 cells were exposed to hydrogen peroxide (H2O2) and then treated with the identified EXD substances. Furthermore, Western blot assay was carried out to identify potential molecular mechanisms involved. For assessing the effect of metabolites in vivo, the SCI model rats were first pretreated with or without the metabolite and then subjected to the immunohistochemistry (IHC) staining, Basso, Beattie & Bresnahan (BBB) locomotor rating scale, and H&E staining. Results: The immobilized PRAS40 isolated indole, 4-nitrophenol, terephthalic acid, palmatine, sinapinaldehyde, and 3-chloroaniline as the potential ligands binding to PRAS40. Furthermore, the association constants of palmatine and indole as 2.84 × 106 M-1 and 3.82 × 105 M-1 were elucidated via ITC due to the drug-like properties of these two metabolites. Molecular docking results also further demonstrated the mechanism of palmatine binding to PRAS40. Western blot analysis of PC12 cells demonstrated that palmatine inhibited the expression of p-mTOR by binding to PRAS40, activating the autophagic flux by markedly increasing LC3. The injection of palmatine (10μM and 20 μM) indicated notably increased BBB scores in the SCI rat model. Additionally, a dose-dependent increase in LC3 was observed by IHC staining. Conclusion: This research proved that EXD comprises PRAS40 antagonists, and the identified metabolite, palmatine, could potentially treat SCI by activating the autophagic flux.

Therapeutic Hypothermia after Cardiac Arrest Attenuates Hindlimb Paralysis and Damage of Spinal Motor Neurons and Astrocytes through Modulating Nrf2/HO-1 Signaling Pathway in Rats

Cardiac arrest (CA) and return of spontaneous circulation (ROSC), a global ischemia and reperfusion event, lead to neuronal damage and/or death in the spinal cord as well as the brain. Hypothermic therapy is reported to protect neurons from damage and improve hindlimb paralysis after resuscitation in a rat model of CA induced by asphyxia. In this study, we investigated roles of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) in the lumbar spinal cord protected by therapeutic hypothermia in a rat model of asphyxial CA. Male Sprague-Dawley rats were subjected to seven minutes of asphyxial CA (induced by injection of 2 mg/kg vecuronium bromide) and hypothermia (four hours of cooling, 33 ± 0.5 °C). Survival rate, hindlimb motor function, histopathology, western blotting, and immunohistochemistry were examined at 12, 24, and 48 h after CA/ROSC. The rats of the CA/ROSC and hypothermia-treated groups had an increased survival rate and showed an attenuated hindlimb paralysis and a mild damage/death of motor neurons located in the anterior horn of the lumbar spinal cord compared with those of the CA/ROSC and normothermia-treated groups. In the CA/ROSC and hypothermia-treated groups, expressions of cytoplasmic and nuclear Nrf2 and HO-1 were significantly higher in the anterior horn compared with those of the CA/ROSC and normothermia-treated groups, showing that cytoplasmic and nuclear Nrf2 was expressed in both motor neurons and astrocytes. Moreover, in the CA/ROSC and hypothermia-treated group, interleukin-1β (IL-1β, a pro-inflammatory cytokine) expressed in the motor neurons was significantly reduced, and astrocyte damage was apparently attenuated compared with those found in the CA/ROSC and normothermia group. Taken together, our results indicate that hypothermic therapy after CA/ROSC attenuates CA-induced hindlimb paralysis by protecting motor neurons in the lumbar spinal cord via activating the Nrf2/HO-1 signaling pathway and attenuating pro-inflammation and astrocyte damage (reactive astrogliosis).

Protective Effect of Mild Hypothermia on Spinal Cord Ischemia-Induced Delayed Paralysis and Spinal Cord Injury

To explore the mechanism regarding the regulation of spinal cord ischemia (SCI) in rats by mild hypothermia. A SCI rat model was established through aorta occlusion, and in some cases, the rats were intervened with mild hypothermia, after which motor function, microglia activation, and M1/M2 polarization in rats were measured. Also, the expression of inflammatory cytokines (IL-1β, IL-6 and TNF-α) and neuronal apoptosis were examined. Lipopolysaccharide (LPS)-induced M1 microglia and IL-4-induced M2 microglia were intrathecally injected into rats to evaluate the effect of microglial polarization on SCI. In in vitro experiments, primary microglial cells were treated under hypothermic condition, in which M1/M2 polarization and microglia apoptosis, the levels of iNOS, CD86, CD206, Arg-1 and inflammatory cytokines were assessed. Western blot analysis detected the activation of the TLR4/NF-κB pathway to investigate the role of this pathway in M1/M2 polarization. SCI treatment impaired motor function, induced higher M1 microglia proportion, and increased the levels of pro-inflammatory cytokines in rats, and mild hypothermic treatment attenuated these trends. Moreover, injection of M1 microglia increased M1 microglia proportion and increased the levels of pro-inflammatory cytokines, while injection of M2 microglia induced the reverse results, i.e. decreased M1 microglia proportion and reduced pro-inflammatory cytokine levels. In LPS-induced microglial cells, mild hypothermia treatment increased M2 microglia proportion and decreased pro-inflammatory cytokine levels, relative to normothermia. Mild hypothermia inactivated the TLR4/NF-κB pathway in LPS-treated microglia. TLR4 overexpression reversed the function of mild hypothermia in LPS-stimulated microglia, and under normal condition, TLR4/NF-κB pathway suppressed microglial M2 polarization. Mild hypothermia inhibits TLR4/NF-κB pathway and promotes microglial M2 polarization, thus attenuating SCI-induced injury and inflammation.

Delving into the recent advancements of spinal cord injury treatment: a review of recent progress

Spinal cord injury (SCI) research is a very complex field lending to why reviews of SCI literatures can be beneficial to current and future researchers. This review focuses on recent articles regarding potential modalities for the treatment and management of SCI. The modalities were broken down into four categories: neuroprotection-pharmacologic, neuroprotection-non-pharmacologic, neuroregeneration-pharmacologic, neuroregeneration-non-pharmacologic. Peer-reviewed articles were found using PubMed with search terms: "spinal cord injury", "spinal cord injury neuroregeneration", "olfactory ensheathing cells spinal cord injury", "rho-rock inhibitors spinal cord injury", "neural stem cell", "scaffold", "neural stem cell transplantation", "exosomes and SCI", "epidural stimulation SCI", "brain-computer interfaces and SCI". Most recent articles spanning two years were chosen for their relevance to the categories of SCI management and treatment. There has been a plethora of pre-clinical studies completed with their results being difficult to replicate in clinical studies. Therefore, scientists should focus on understanding and applying the results of previous research to develop more efficacious preclinical studies and clinical trials.

Therapeutic Effects of Risperidone against Spinal Cord Injury in a Rat Model of Asphyxial Cardiac Arrest: A Focus on Body Temperature, Paraplegia, Motor Neuron Damage, and Neuroinflammation

Cardiac arrest (CA) causes severe spinal cord injury and evokes spinal cord disorders including paraplegia. It has been reported that risperidone, an antipsychotic drug, effectively protects neuronal cell death from transient ischemia injury in gerbil brains. However, until now, studies on the effects of risperidone on spinal cord injury after asphyxial CA (ACA) and cardiopulmonary resuscitation (CPR) are not sufficient. Therefore, this study investigated the effect of risperidone on hind limb motor deficits and neuronal damage/death in the lumbar part of the spinal cord following ACA in rats. Mortality, severe motor deficits in the hind limbs, and the damage/death (loss) of motor neurons located in the anterior horn were observed two days after ACA/CPR. These symptoms were significantly alleviated by risperidone (an atypical antipsychotic) treatment after ACA. In vehicle-treated rats, the immunoreactivities of tumor necrosis factor-alpha (TNF-α) and interleukin 1-beta (IL-1β), as pro-inflammatory cytokines, were increased, and the immunoreactivities of IL-4 and IL-13, as anti-inflammatory cytokines, were reduced with time after ACA/CPR. In contrast, in risperidone-treated rats, the immunoreactivity of the pro-inflammatory cytokines was significantly decreased, and the anti-inflammatory cytokines were enhanced compared to vehicle-treated rats. In brief, risperidone treatment after ACA/CPR in rats significantly improved the survival rate and attenuated paralysis, the damage/death (loss) of motor neurons, and inflammation in the lumbar anterior horn. Thus, risperidone might be a therapeutic agent for paraplegia by attenuation of the damage/death (loss) of spinal motor neurons and neuroinflammation after ACA/CPR.

Higenamine mitigates interleukin-1β-induced human nucleus pulposus cell apoptosis by ROS-mediated PI3K/Akt signaling

Intervertebral disc degeneration (IDD) is a natural problem linked to the inflammation. Higenamine exerts multiple pharmacological properties in inflammation-related disorders. Our study aimed to explore the function of higenamine on interleukin (IL)-1β-caused apoptosis of human nucleus pulposus cells (HNPCs). Cell apoptosis was investigated by TUNEL and flow cytometry. Apoptosis-related biomarkers were determined by qRT-PCR or Western blotting. The protein in the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling was measured by Western blotting. We found that higenamine showed little effect on cell apoptosis, but mitigated IL-1β-caused apoptosis in a dose-dependent pattern. Higenamine attenuated IL-1β-induced decrease of Bcl-2 and increase of Bax and cleaved caspase-3. Higenamine did not affect the reactive oxygen species (ROS) level and the PI3K/Akt signaling, but attenuated IL-1β-induced ROS production and inhibition of the PI3K/Akt signaling. IL-1β repressed the activation of the PI3K/Akt pathway, but ROS inhibition using N-acetylcysteine (NAC) rescued this pathway. The PI3K/Akt signaling suppression using LY294002 reversed the inhibitive effect of higenamine on IL-1β-caused apoptosis, and this effect was weakened by ROS inhibition. In conclusion, higenamine attenuates IL-1β-caused apoptosis of HNPCs via ROS-mediated PI3K/Akt pathway.

Effects of hypothermia on inflammatory cytokine expression in rat liver following asphyxial cardiac arrest

Hypothermic treatment is known to protect against cardiac arrest (CA) and improve survival rate. However, few studies have evaluated the CA-induced liver damage and the effects of hypothermia on this damage. Therefore, the aim of the present study was to determine possible protective effects of hypothermia on the liver after asphyxial CA. Rats were subjected to a 5-min asphyxial CA followed by return of spontaneous circulation (ROSC). The body temperature was controlled at 37±0.5˚C (normothermia group) or 33±0.5˚C (hypothermia group) for 4 h after ROSC. Livers were examined at 6, 12 h, 1 and 2 days after ROSC. Histopathological examination was performed by H&E staining. Alterations in the expression levels of pro-inflammatory (TNF-α and interleukin IL-2) and anti-inflammatory cytokines (IL-4 and IL-13) were investigated by immunohistochemistry. Sinusoidal dilatation and vacuolization were observed after asphyxial CA by histopathological examination. However, these CA-induced structural alterations were prevented by hypothermia. In immunohistochemical examination, the expression levels of pro-inflammatory cytokines were reduced in the hypothermia group compared with those in the normothermia group while the expression levels of anti-inflammatory cytokines were increased in the hypothermia group compared with those in the normothermia group. In conclusion, hypothermic treatment for 4 h following asphyxial CA in rats inhibited the increase of pro-inflammatory cytokines and stimulated the expression of anti-inflammatory cytokines compared with the normothermic group. The results of the present study suggested that hypothermic treatment after asphyxial CA reduced liver damage via the regulation of inflammation.

Neurologic complications of cardiac arrest

Cardiac arrest is a catastrophic event with high morbidity and mortality. Despite advances over time in cardiac arrest management and postresuscitation care, the neurologic consequences of cardiac arrest are frequently devastating to patients and their families. Targeted temperature management is an intervention aimed at limiting postanoxic injury and improving neurologic outcomes following cardiac arrest. Recovery of neurologic function governs long-term outcome after cardiac arrest and prognosticating on the potential for recovery is a heavy burden for physicians. An early and accurate estimate of the potential for recovery can establish realistic expectations and avoid futile care in those destined for a poor outcome. This chapter reviews the epidemiology, pathophysiology, therapeutic interventions, prognostication, and neurologic sequelae of cardiac arrest.

Healthful aging mediated by inhibition of oxidative stress

The progressive increase in lifespan over the past century carries with it some adversity related to the accompanying burden of debilitating diseases prevalent in the older population. This review focuses on oxidative stress as a major mechanism limiting longevity in general, and healthful aging, in particular. Accordingly, the first goal of this review is to discuss the role of oxidative stress in limiting longevity, and compare healthful aging and its mechanisms in different longevity models. Secondly, we discuss common signaling pathways involved in protection against oxidative stress in aging and in the associated diseases of aging, e.g., neurological, cardiovascular and metabolic diseases, and cancer. Much of the literature has focused on murine models of longevity, which will be discussed first, followed by a comparison with human models of longevity and their relationship to oxidative stress protection. Finally, we discuss the extent to which the different longevity models exhibit the healthful aging features through physiological protective mechanisms related to exercise tolerance and increased β-adrenergic signaling and also protection against diabetes and other metabolic diseases, obesity, cancer, neurological diseases, aging-induced cardiomyopathy, cardiac stress and osteoporosis.

The Spinal Cord Damage in a Rat Asphyxial Cardiac Arrest/Resuscitation Model

BACKGROUND

After cardiac arrest/resuscitation (CA/R), animals often had massive functional restrictions including spastic paralysis of hind legs, disturbed balance and reflex abnormalities. Patients who have survived CA also develop movement restrictions/disorders. A successful therapy requires detailed knowledge of the intrinsic damage pattern and the respective mechanisms. Beside neurodegenerations in the cerebellum and cortex, neuronal loss in the spinal cord could be a further origin of such movement artifacts.

METHODS

Thus, we aimed to evaluate the CA/R-induced degeneration pattern of the lumbar medulla spinalis by immunocytochemical expression of SMI 311 (marker of neuronal perikarya and dendrites), IBA1 (microglia marker), GFAP (marker of astroglia), calbindin D28k (marker of the cellular neuroprotective calcium-buffering system), MnSOD (neuroprotective antioxidant), the transcription factor PPARγ and the mitochondrial marker protein PDH after survival times of 7 and 21 days. The CA/R specimens were compared with those from sham-operated and completely naïve rats. RESULTS & CONCLUSION: The main ACA/R-mediated results were: (1) degeneration of lumbar spinal cord motor neurons, characterized by neuronal pyknotization and peri-neuronal tissue artifacts; (2) attendant activation of microglia in the short-term group; (3) attendant activation of astroglia in the long-term group; (4) degenerative pattern in the intermediate gray matter; (5) activation of the endogenous anti-oxidative defense systems calbindin D28k and MnSOD; (6) activation of the transcription factor PPARγ, especially in glial cells of the gray matter penumbra; and (7) activation of mitochondria. Moreover, marginal signs of anesthesia-induced cell stress were already evident in sham animals when compared with completely naïve spinal cords. A correlation between the NDS and the motor neuronal loss could not be verified. Thus, the NDS appears to be unsuitable as prognostic tool.