[Cannabinoid receptor 1 agonist arachidonyl-2'-chloroethylamide (ACEA) improves sepsis-associated encephalopathy by inhibiting inflammatory factors].

Objective To investigate the impact of the cannabinoid receptor agonist arachidonyl-2'-chloroethylamide (ACEA) on cognitive function in mice with sepsis-associated encephalopathy (SAE). Methods C57BL/6 mice were randomly divided into artificial cerebrospinal fluid (ACSF) and lipopolysaccharide (LPS) groups. The SAE model was established by intraventricular injection of LPS. The severity of sepsis in mice was assessed by sepsis severity score (MSS) and body mass changes. Behavioral paradigms were used to evaluate motor ability (open field test) and cognitive function (contextual fear conditioning test, Y-maze test). To evaluate the effects of ACEA intervention on SAE, mice were randomly assigned to ACSF group, ACEA intervention combined with ACSF group, LPS group, and ACEA intervention combined with LPS group. The dosage of ACEA intervention was 1.5 mg/kg. Real-time quantitative PCR was used to measure the mRNA expression levels of interleukin 1ß (IL-1ß), IL-6, and tumor necrosis factor α (TNF-α) in mouse hippocampal tissues. Western blot analysis was used to assess the protein levels of IL-6 and TNF-α in the hippocampus. Nissl staining was performed to examine neuronal damage in the CA1 region of the mouse hippocampus. Behavioral paradigms were again employed to evaluate motor ability and cognitive function. Results Three days after intraventricular LPS injection, mice exhibited significant cognitive dysfunction, confirming SAE modeling. Compared to the control group, the LPS group showed significant increases in mRNA of inflammatory factors such as IL-6, TNF-α, and IL-1ß, together with significant increases in IL-6 and TNF-α protein levels in the hippocampus, a decrease in Nissl bodies in the CA1 region, and significant cognitive dysfunction. Compared to the LPS group, the ACEA intervention group showed a significant decrease in the mRNA of IL-6, TNF-α, and IL-1ß, a significant reduction in IL-6 and TNF-α protein levels, an increase in Nissl bodies, and improved cognitive function. Conclusion ACEA improves cognitive function in SAE mice by inhibiting the expression levels of inflammatory factors IL-6 and TNF-α.

LncRNA RPL29P2 promotes peritoneal fibrosis and impairs peritoneal transport function via miR-1184 in peritoneal dialysis.

Peritoneal dialysis (PD), hemodialysis and kidney transplantation are the three therapies to treat uremia. However, PD is discontinued for peritoneal membrane fibrosis (PMF) and loss of peritoneal transport function (PTF) due to damage from high concentrations of glucose in PD fluids (PDFs). The mechanism behind PMF is unclear, and there are no available biomarkers for the evaluation of PMF and PTF. Using microarray screening, we found that a new long noncoding RNA (lncRNA), RPL29P2, was upregulated in the PM (peritoneal membrane) of long-term PD patients, and its expression level was correlated with PMF severity and the PTF loss. In vitro and rat model assays suggested that lncRNA RPL29P2 targets miR-1184 and induces the expression of collagen type I alpha 1 chain (COL1A1). Silencing RPL29P2 in the PD rat model might suppress the HG-induced phenotypic transition of Human peritoneal mesothelial cells (HPMCs), alleviate HG-induced fibrosis and prevent the loss of PTF. Overall, our findings revealed that lncRNA RPL29P2, which targets miR-1184 and collagen, may represent a useful marker and therapeutic target of PMF in PD patients.

Immune checkpoint activity exacerbate renal interstitial fibrosis progression by enhancing PD-L1 expression in renal tubular epithelial cells.

Renal interstitial fibrosis (RIF) is often associated with inflammatory cell infiltration and no effective therapy. Programmed death cell-1 (PD-1) and its ligand PD-L1 were playing critical roles in T cell coinhibition and exhaustion, but the role in RIF is unclear. Here the data analyses of serum from 122 IgA nephrology (IgAN) patients showed that high level of soluble PD-1(sPD-1) was an independent risk factor for RIF and renal function progression. PD-L1 was also overexpressed in renal interstitial tissues from both IgAN patients with high level of sPD-1 and the unilateral ureteral obstruction (UUO) mouse. PD-L1 was significantly overexpressed in HK-2 cells with upregulated collagen and α-SMA when stimulated by inflammation or hypoxia in vitro. Additionally, matrix metalloproteinases (MMP-2) could increase the level of sPD-1 in culture supernatant when added in co-culture system of HK-2 and jurkat cells, which implied serum sPD-1 of IgAN might be cleaved by MMP-2 from T cells infiltrated into the tubulointerstitial inflammatory microenvironment. Crucially, injection of PD-L1 fusion protein, the blocker of sPD-1, could ameliorate kidney fibrosis in UUO mice by increasing T cell coinhibition and exhaustion, suggesting the therapeutic potential of PD-L1 fusion targeting for renal fibrosis. Take together, it reveals a novel causal role of sPD-1 in serum and PD-L1 of renal interstitial tissues in the development of renal fibrosis of IgAN, and targeting sPD-1 in serum by PD-L1 fusion protein is a potential therapeutic approach to prevent renal fibrosis of IgAN.

Effects of Nalbuphine on Gastrointestinal Function in Post-Operative Critical Ill Patients Admitted to the ICU: A Multicenter Randomized Controlled Trial.

BACKGROUND: Gastrointestinal (GI) function can be a significant problem in critically ill patients and is associated with detrimental outcomes. The administration of opioids for pain reduction is thought to contribute to GI dysfunction. We tested whether nalbuphine, a mixed agonist/antagonist opioid modulator, can promote GI recovery in postoperative critical patients admitted to the intensive care unit (ICU) and compared it with fentanyl, a selective mu opioid receptor (MOR) agonist. METHODS: This is a multicenter, single-blind, randomized controlled trial to investigate whether nalbuphine improves the GI recovery in ICU patients after surgery, and compared it with fentanyl. The primary outcome was the time to first defecation. Secondary outcomes included the use of sedatives, enemas or laxatives, the acute gastrointestinal injury (AGI) grade, the incidence of vomiting, and the lengths of ICU and hospital stays. RESULTS: We randomized 436 patients, and a total of 369 patients were included in the modified intention-to-treat population (mITT) (185 to the nalbuphine group and 184 to the fentanyl group). The baseline demographic characteristics of the two groups were comparable after randomization. There was no significant difference in the time to defecation between the two groups [hazard ratio (HR) 0.94, 95% CI 0.74-1.19, p = 0.62]. There was no significant difference in the secondary outcomes between the two groups. CONCLUSION: We found no evidence that nalbuphine administration can improve the GI function in postoperative critical patients admitted to the ICU compared with fentanyl. However, the CI was wide and we could not exclude the clinically important difference.

Microglia in the Pathophysiology of Hemorrhagic Stroke and the Relationship Between Microglia and Pain After Stroke: A Narrative Review.

Stroke is a leading cause of death worldwide, and about a quarter of stroke patients are dead within 1 month. The prognosis is even worse for those with hemorrhagic stroke because the 1-month mortality approaches 50%. Besides, most patients who survive experience complications such as nausea, vomiting, and chronic pain. These adverse experiences, especially the existence of chronic pain, can lead to a decline in the patient's quality of life. In order to improve the treatment and prognosis of hemorrhagic stroke, there is an urgent need to understand its pathophysiological mechanism as well as the chronic pain it induces. This paper reviews studies of the molecular mechanisms of hemorrhagic stroke, especially the activation of microglia and the relationship between microglia and pain after stroke, which could shed new light on hemorrhagic stroke treatment.

Rosmarinic acid protects rats against post-stroke depression after transient focal cerebral ischemic injury through enhancing antioxidant response.

Rosmarinic acid (RA), a natural polyphenol, possesses potent antioxidant and anti-inflammatory activities. To evaluate the ability of RA to cure ischemic stroke and post-stroke depression (PSD), rats were treated with various doses of RA after cerebral ischemia. Neurological deficits and infarct volume of the brain were measured. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) were examined at different time points. In addition, a forced swimming test and sucrose preference test were performed to detect the anti-depressive effects of RA. Our results revealed RA administration significantly alleviated neurological deficits and reduced infarct volumes. RA attenuated the decrease of SOD, CAT activities and GSH levels in the ischemic penumbra of the brain. Most importantly, RA treatment alleviated the depression behaviors. Increased expression of Nrf2 was also induced by RA, while down regulation Nrf2 by Nrf2-short-hairpin RNA sequences reversed the increasing activity of SOD and CAT induced by RA, as well as the protection against PSD. The present study indicates that RA exerts a potent neuroprotective effect against stroke and PSD, which could be a promising therapeutic intervention for stroke.

Microglia: A Potential Therapeutic Target for Sepsis-Associated Encephalopathy and Sepsis-Associated Chronic Pain.

Neurological dysfunction, one of the severe manifestations of sepsis in patients, is closely related to increased mortality and long-term complications in intensive care units, including sepsis-associated encephalopathy (SAE) and chronic pain. The underlying mechanisms of these sepsis-induced neurological dysfunctions are elusive. However, it has been well established that microglia, the dominant resident immune cell in the central nervous system, play essential roles in the initiation and development of SAE and chronic pain. Microglia can be activated by inflammatory mediators, adjacent cells and neurotransmitters in the acute phase of sepsis and then induce neuronal dysfunction in the brain. With the spotlight focused on the relationship between microglia and sepsis, a deeper understanding of microglia in SAE and chronic pain can be achieved. More importantly, clarifying the mechanisms of sepsis-associated signaling pathways in microglia would shed new light on treatment strategies for SAE and chronic pain.

Protocol for a randomized controlled trial testing inhaled nitric oxide therapy in spontaneously breathing patients with COVID-19.

Introduction: the current worldwide outbreak of Coronavirus disease 2019 (COVID-19) due to a novel coronavirus (SARS-CoV-2) is seriously threatening the public health. The number of infected patients is continuously increasing and the need for Intensive Care Unit admission ranges from 5 to 26%. The mortality is reported to be around 3.4% with higher values for the elderly and in patients with comorbidities. Moreover, this condition is challenging the healthcare system where the outbreak reached its highest value. To date there is still no available treatment for SARS-CoV-2. Clinical and preclinical evidence suggests that nitric oxide (NO) has a beneficial effect on the coronavirus-mediated acute respiratory syndrome, and this can be related to its viricidal effect. The time from the symptoms' onset to the development of severe respiratory distress is relatively long. We hypothesize that high concentrations of inhaled NO administered during early phases of COVID-19 infection can prevent the progression of the disease. Methods and analysis: This is a multicenter randomized controlled trial. Spontaneous breathing patients admitted to the hospital for symptomatic COVID-19 infection will be eligible to enter the study. Patients in the treatment group will receive inhaled NO at high doses (140-180 parts per million) for 30 minutes, 2 sessions every day for 14 days in addition to the hospital care. Patient in the control group will receive only hospital care. The primary outcome is the percentage of patients requiring endotracheal intubation due to the progression of the disease in the first 28 days from enrollment in the study. Secondary outcomes include mortality at 28 days, proportion of negative test for SARS-CoV-2 at 7 days and time to clinical recovery. Ethics and dissemination: The trial protocol has been approved at the Investigation Review Boards of Xijing Hospital (Xi'an, China) and The Partners Human Research Committee of Massachusetts General Hospital (Boston, USA) is pending. Recruitment is expected to start in March 2020. Results of this study will be published in scientific journals, presented at scientific meetings, and on related website or media in fighting this widespread contagious disease.

Protocol of a randomized controlled trial testing inhaled Nitric Oxide in mechanically ventilated patients with severe acute respiratory syndrome in COVID-19 (SARS-CoV-2).

Introduction: Severe acute respiratory syndrome due to novel Coronavirus (SARS-CoV-2) related infection (COVID-19) is characterized by severe ventilation perfusion mismatch leading to refractory hypoxemia. To date, there is no specific treatment available for COVID-19. Nitric oxide is a selective pulmonary vasodilator gas used as a rescue therapy in refractory hypoxemia due to acute respiratory distress syndrome (ARDS). In has also shown invitro and clinical evidence that inhaled nitric oxide gas (iNO) has antiviral activity against other strains of coronavirus. The primary aim of this study is to determine whether inhaled NO improves oxygenation in patients with hypoxic COVID-19. This is a multicenter randomized controlled trial with 1:1 individual allocation. Patients will be blinded to the treatment. Methods and analysis: Intubated patients admitted to the intensive care unit with confirmed SARS-CoV-2 infection and severe hypoxemia will be randomized to receive inhalation of NO (treatment group) or not (control group). Treatment will be stopped when patients are free from hypoxemia for more than 24 hours. The primary outcome evaluates levels of oxygenation between the two groups at 48 hours. Secondary outcomes include rate of survival rate at 28 and 90 days in the two groups, time to resolution of severe hypoxemia, time to achieve negativity of SARS-CoV-2 RT-PCR tests. Ethics and dissemination: The study protocol has been approved by the Investigational Review Board of Xijing Hospital (Xi'an, China) and by the Partners Human Research Committee (Boston, USA). Recruitment will start after approval of both IRBs and local IRBs at other enrolling centers. Results of this study will be published in scientific journals, presented at scientific meetings, reported through flyers and posters, and published on related website or media in combating against this widespread contagious disease. Trial registration: Clinicaltrials.gov. NCT04306393.

[How to improve the teaching ability of young teachers of critical care medicine?]

Intensive care unit (ICU) in teaching hospital plays important roles in teaching work. The young teachers of critical care medicine are gradually becoming the backbone of teaching work. Improving the teaching ability of young teachers is essential to increase learning motivation of the students and to promote the overall teaching quality of critical care medicine. Therefore, pay attention to help the young teachers of critical care medicine to improve their teaching skill is good for enhancing the faculty developing of critical care medicine, as well as essential for the prosperity and sustainable development of critical care medicine. Based on the problems existing during the teaching process of young teachers of critical care medicine and aimed to train excellent teachers, this article discussed the teaching methods and experience of young teachers of critical care medicine which focuses on teaching program design, class affinity improvement and humanistic education in order to improve the teaching level of young teachers of critical care medicine.

Male sexual dysfunction: A review of literature on its pathological mechanisms, potential risk factors, and herbal drug intervention.

Sexual dysfunction (SD) is a disorder of sexual behavior and sexual sensation that appears as an abnormality or absence of sexual psychology and physiological reaction. It is a general term for many different symptoms includes several aspects, erectile dysfunction (ED), failure of sexual intercourse and loss of libido/desire. According to statistics, 52% of 40˜70 year old men suffer from varying degrees of SD. And these diseases caused by a variety of biological and psychological factors. In world about 15% of couples are affected by sexual disharmony among these 40 to 50% are because of male factors. Considering the sensitivity of male reproduction system, it is being easily affected by multiple risk factors, such as chronic diseases, environmental contaminants, drug toxicity and unhealthy lifestyle and so on. In the last few years, significant progress have been made toward understanding the various forms of male SD and the possible potential pathological mechanisms. However, for the time being, the exact cause of SD is not fully understood from the literature. What is also significant about there are quite limited treatments in reproductive medicine being directed against these lesions. The purpose of this review is to summarize the current findings of pathogenic factors of SD in clinical or animal studies, to elaborate the underlying mechanisms of these diseases from studies in vivo and in vitro, to analyses the risk factors, and to describe the management strategies traditionally recommended of male sexual dysfunction. The review findings elucidate a systematic strategies for effectively preventing these diseases.

Inhibiting a spinal cord signaling pathway protects against ischemia injury in rats.

OBJECTIVE: The aim of the study was to examine whether the cannabinoid agonist WIN55212-2 could attenuate ischemic spinal cord injury (SCI) in rats through inhibition of GAPDH/Siah1 signaling. METHODS: Male Sprague-Dawley rats were distributed randomly into 5 groups: (1) sham group that received no aortic occlusion and injected intraperitoneally (i.p.) with vehicle control after reperfusion; (2) control group that received a 12-minute aortic occlusion and injected i.p. with vehicle control after reperfusion; (3) WIN55212-2 group (WIN) that received the aortic occlusion and injected i.p. with 1 mg/kg of WIN55212-2 after reperfusion; and (4) WIN55212-2 plus AM251 group and (5) WIN55212-2 plus AM630 group that received the same surgical operation as the WIN group, except that 1 mg/kg of AM251 or AM630 was injected i.p. 30 min before each dose of WIN55212-2 injection, respectively. Neurologic function was assessed 48 hours after reperfusion. Histopathologic examination was performed to determine the number of normal neurons in anterior spinal cord. Protein expression of active caspase-3, total caspase-3, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), inducible nitric oxide synthase (iNOS), nuclear factor kappa light chain enhancer of activated B cells (NF-κB), Siah1, tumor necrosis factor α, and interleukin 1ß were determined with Western blot and enzyme-linked immunosorbent assay; coimmunoprecipitation assays were also used to determine GAPDH/Siah1 complexing. Finally, terminal deoxynucleotidyl transferase dUTP nick end labeling staining was used to determine neuronal apoptosis in the lumbar spinal cord. RESULTS: The nuclear translocation of GAPDH and Siah1 in the spinal cord was initiated after ischemic spinal cord injury (SCI) along with the increased formation of GAPDH/Siah1 complexes. However, the activation of GAPDH/Siah1 was blocked by WIN. In addition, the treatment of WIN55212-2 promoted neuronal survival in the spinal cord, reduced apoptosis and inflammation, and improved neurologic scores. Furthermore, these beneficial effects of WIN55212-2 were abolished by the combined treatment of the CB2 antagonist AM630, but not the CB1 antagonist AM251. CONCLUSIONS: Our findings reveal GAPDH/Siah1 signaling cascades as a novel therapeutic target for ischemic SCI and identify WIN55212-2 with the potential to treat ischemic SCI by targeting this pathway.

The synthetic cannabinoid WIN55212-2 ameliorates traumatic spinal cord injury via inhibition of GAPDH/Siah1 in a CB2-receptor dependent manner.

The essential role of GAPDH/Siah1 signaling pathway in the pathogenesis of various injurious conditions such as traumatic spinal cord injury (SCI) has been gradually recognized. However, the drugs targeting this signaling pathway are still lacking. The endocannabinoid system, including its receptors (CB1 and CB2), act as neuroprotective and immunomodulatory modulators in SCI. WIN55212-2, an agonist for CB1 and CB2 receptors, has been demonstrated with anti-inflammatory and anti-apoptotic effects in multiple neurological diseases. Therefore, the present study aimed to investigate whether WIN55212-2 could promote functional recovery after traumatic SCI via inhibition of the GAPDH/Siah1 signaling. The traumatic SCI was induced by dropping a 10-g impactor from 25mm on the dorsal surface of T9 and T10. Our results showed that WIN55212-2 alleviated the activation of GAPDH/Siah1 signaling pathway after SCI, as indicated by the reduction in GAPDH nuclear expression, GAPDH-Siah1 complex formation and iNOS protein expression. Furthermore, WIN55212-2 reduced apoptosis, production of IL-1ß and TNF-α and activation of NF-κB signaling in the spinal cord after SCI. The behavioral tests showed that WIN55212-2 improved the functional recovery after traumatic SCI as indicated by sustained increase in the locomotor scores. However, these neuroprotective effects of WIN55212-2 were blocked in the presence of the combined treatment of AM630 (an antagonist of CB2) rather than AM251 (an antagonist of CB1). In conclusion, our study indicates that, WIN55212-2 improves the functional recovery after SCI via inhibition of GAPDH/Siah1 cascades in a CB2 receptor dependent manner, indicative of its therapeutic potential for traumatic SCI or other traumatic conditions.

Electroacupuncture pretreatment attenuates spinal cord ischemia-reperfusion injury via inhibition of high-mobility group box 1 production in a LXA4 receptor-dependent manner.

Paraplegia caused by spinal cord ischemia is a severe complication following surgeries in the thoracic aneurysm. HMGB1 has been recognized as a key mediator in spinal inflammatory response after spinal cord injury. Electroacupuncture (EA) pretreatment could provide neuroprotection against cerebral ischemic injury through inhibition of HMGB1 release. Therefore, the present study aims to test the hypothesis that EA pretreatment protects against spinal cord ischemia-reperfusion (I/R) injury via inhibition of HMGB1 release. Animals were pre-treated with EA stimulations 30min daily for 4 successive days, followed by 20-min spinal cord ischemia induced by using a balloon catheter placed into the aorta. We found that spinal I/R significantly increased mRNA and cytosolic protein levels of HMGB1 after reperfusion in the spinal cord. The EA-pretreated animals displayed better motor performance after reperfusion along with the decrease of apoptosis, HMGB1, TNF-α and IL-1ß expressions in the spinal cord, whereas these effects by EA pretreatment was reversed by rHMGB1 administration. Furthermore, EA pretreatment attenuated the down-regulation of LXA4 receptor (ALX) expression induced by I/R injury, while the decrease of HMGB1 release in EA-pretreated rats was reversed by the combined BOC-2 (an inhibitor of LXA4 receptor) treatment. In conclusion, EA pretreatment may promote spinal I/R injury through the inhibition of HMGB1 release in a LXA4 receptor-dependent manner. Our data may represent a new therapeutic technique for treating spinal cord ischemia-reperfusion injury.

Neuroprotective effect of endogenous cannabinoids on ischemic brain injury induced by the excess microglia-mediated inflammation.

Increasing evidence has demonstrated the role of endogenous cannabinoids system (ECS) on protecting brain injury caused by ischemia (IMI). Papers reported that microglia-mediated inflammation has become one of the most pivotal mechanisms for IMI. This study was aimed to investigate the potential roles of ECS on neuron protection under microglia-mediated inflammation. Inflammatory cytokines level both in vitro (BV-2 cells) and in vivo (brain tissue from constructed IMI model and brain-isolated microglia) was detected. ECS levels were detected, and its effects on inflammations was also analyzed. Influence of microglia-mediated inflammation on neuron injury was analyzed. Moreover, the effects of ECS on protecting neuron injury were also analyzed. Our results showed that the levels of inflammatory cytokines including TNFα and IL-1ß were higher while IKBα was lower in IMI model brain tissue, brain-isolated microglia and BV-2 cells compared to the control. Inflammation was activated in microglia, as well as the activation of ECS characterized by the increasing level of AEA and 2-AG. Furthermore, the activated microglia-mediated self-inflammation performed harmful influence on neurons via suppressing cell viability and inducing apoptosis. Moreover, ECS functioned as a protector on neuron injury though promoting cell proliferation and suppressing cell apoptosis which were caused by the activated BV-2 cells (LPS induced for 3 h). Our data suggested that ECS may play certain neuroprotective effects on microglia-mediated inflammations-induced IMI through anti-inflammatory function.

GAPDH/Siah1 cascade is involved in traumatic spinal cord injury and could be attenuated by sivelestat sodium.

The glyceraldehyde-3-phosphate dehydrogenase (GAPDH)/Siah1 signaling pathway has been recognized as a sensor of nitric oxide (NO). It is associated with a variety of injurious conditions, suggesting its therapeutic potential for spinal cord injury (SCI). Sivelestat sodium (SIV), a neutrophil elastase (NE) inhibitor initially used to treat acute lung injury, has been known to protect against compression-induced and ischemic SCI. However, little is known about the relationship between the GAPDH/Siah1 cascade and SIV. Thus, we aimed to assess the role of GAPDH/Siah1 cascade in traumatic SCI and its possible link with SIV. Rats were assigned to four groups: sham group, SCI group, 5-mg/kg SIV group, and 10-mg/kg SIV. The traumatic SCI was induced by dropping a 10-g impactor from a height of 25mm on the dorsal surface of T9 and T10. SIV was injected intraperitoneally immediately after surgery. Our results showed that the nuclear translocation of GAPDH was induced together with the nuclear translocation of Siah1 and the formation of the GAPDH/Siah1 complex in the spinal cord after traumatic SCI. However, the activation of the GAPDH/Siah1 cascade was attenuated by treatment with SIV. We also found that SIV suppressed apoptosis, NE and inducible nitric oxide synthase (iNOS) protein expressions, the number of NE and iNOS immunostained cells, the production of interleukin (IL)-1ß and tumor necrosis factor-alpha (TNF-α), and the activation of nuclear factor kappa light-chain enhancer of activated B cells (NF-κB) signaling in the spinal cord. The behavioral tests showed that SIV promoted functional recovery after traumatic SCI as reflected in the sustained increase in the Basso-Beattie-Bresnahan (BBB) scores throughout the observation period. In conclusion, our results reveal GAPDH/Siah1 as a novel signaling pathway during the progression of SCI, which can be blocked by SIV.

The neuroprotective effects of isoflurane preconditioning in a murine transient global cerebral ischemia-reperfusion model: the role of the Notch signaling pathway.

Inhalational anesthetic preconditioning can induce neuroprotective effects, and the notch signaling pathway plays an important role in neural progenitor cell differentiation and the inflammatory response after central nervous system injury. This study evaluated whether the neuroprotective effect of isoflurane preconditioning is mediated by the activation of the notch signaling pathway. Mice were divided into two groups consisting of those that did or did not receive preconditioning with isoflurane. The expression levels of notch-1, notch intracellular domain (NICD), and hairy and enhancer of split (HES-1) were measured in mice subjected to transient global cerebral ischemia-reperfusion injury. The notch signaling inhibitor DAPT and conditional notch-RBP-J knockout mice were used to investigate the mechanisms of isoflurane preconditioning-induced neuroprotection. Immunohistochemical staining, real-time polymerase chain reaction assays, and Western blotting were performed. Isoflurane preconditioning induced neuroprotection against global cerebral ischemia. Preconditioning up-regulated the expression of notch-1, HES-1, and NICD after ischemic-reperfusion. However, these molecules were down-regulated at 72 h after ischemic-reperfusion. The inhibition of notch signaling activity by DAPT significantly attenuated the isoflurane preconditioning-induced neuroprotection, and similar results were obtained using notch knockout mice. Our results demonstrate that the neuroprotective effects of isoflurane preconditioning are mediated by the pre-activation of the notch signaling pathway.

Ischemic postconditioning protects the spinal cord from ischemia-reperfusion injury via modulation of redox signaling.

BACKGROUND: It is well known that ischemic postconditioning reduces ischemic-reperfusion injury, but the underlying mechanism is not fully understood. The current study investigated the role of reactive oxygen species-mediated upregulation of endogenous antioxidant enzymes in the generation of a protective effect induced by ischemic postconditioning against spinal cord reperfusion injury in the rabbit. METHODS: New Zealand White rabbits were randomly allocated to sham, ischemia-reperfusion, and postconditioning groups (3 cycles of 30 seconds of reperfusion and 30 seconds of occlusion during the onset of reperfusion). Spinal cord ischemia was induced by clamping the infrarenal abdominal aorta for 20 minutes in the ischemia-reperfusion and postconditioning groups. Forty-eight hours after reperfusion, the neurologic status of the lower limbs was assessed. Blood samples were collected for analysis of serum neuron-specific enolase levels, and the lumbar spinal cord segments (L5-7) were harvested for histopathologic and antioxidant enzyme activities and mRNA analysis with or without administration of N-2-mercaptopropionylglycine (an effective oxygen free radical scavenger) given at different reperfusion times. RESULTS: Continuous administration of N-2-mercaptopropionylglycine for 13 minutes, starting at 10 minutes before (but not 10 minutes after) the beginning of reperfusion, attenuated the neuroprotective effect of postconditioning against spinal cord ischemia and reversed the increase in activity of the antioxidant enzymes superoxide dismutase and catalase in spinal cord tissue subjected to ischemic postconditioning. CONCLUSIONS: The results indicate that reactive oxygen species-triggered upregulation of endogenous antioxidant enzyme activities may be involved in the mechanism of neuroprotection of ischemic postconditioning.

TREK1 activation mediates spinal cord ischemic tolerance induced by isoflurane preconditioning in rats.

The aim of this study is to examine the role of one of the two-pore (2P) domain K(+) channels, TREK (TWIK-related K(+) channels, TREK)-1, mediated neuroprotection on spinal cord afforded by isoflurane preconditioning. In Experiment 1, male Sprague-Dawley rats were randomly assigned to control (Con) group, an isoflurane preconditioning (Iso) group, and sham group. Twenty-four hours after the last pretreatment, spinal cord ischemia was induced in Con and Iso groups. Neurobehavioral testing and histopathologic examination were performed after reperfusion. In Experiment 2, the expression of the TREK1 in the spinal cord was assessed by immunohistochemistry, Western blot and real-time polymerase chain reaction. In Experiment 3, Amiloride, a blocker of stretch-sensitive channels, was administered intraperitoneally immediately prior to each isoflurane preconditioning. Iso group showed a significant reductions in motor deficit index as well as increases in the number of normal neurons compared with the Con group. The expression of TREK1 protein and the level of mRNA after ischemia were higher in the rats of the Iso group than those in the Con group. Amiloride pretreatment abolished the protective effects of Iso preconditioning. These finding indicate that isoflurane preconditioning had a neuroprotective effect against spinal cord ischemia reperfusion injury. These effects may be mediated through the TREK1 pathway.

Limb remote ischemic preconditioning protects the spinal cord from ischemia-reperfusion injury: a newly identified nonneuronal but reactive oxygen species-dependent pathway.

BACKGROUND: It remains to be established whether spinal cord ischemic tolerance can be induced by limb remote ischemic preconditioning (RIPC), and the mechanisms underlying the neuroprotective effects of RIPC on the spinal cord need to be clarified. METHODS: Spinal cord ischemia was studied in New Zealand White rabbits. In experiment 1, all rabbits were subjected to 20-min spinal cord ischemia by aortic occlusion. Thirty minutes before ischemia, rabbits were subjected to sham intervention or RIPC achieved by bilateral femoral artery occlusion (10 min ischemia/10 min reperfusion, two cycles). Dimethylthiourea (500 mg/kg, intravenously), a hydroxyl radical scavenger, or vehicle was given 1 h before RIPC. Antioxidant enzyme activity was measured along with spinal cord histology and neurologic function. In experiment 2, rabbits were subjected to spinal cord ischemia, with or without RIPC. In addition, rabbits were pretreated with various doses of hexamethonium. RESULTS: RIPC improved neurologic function and reduced histologic damage. This was associated with increased endogenous antioxidant activity. Dimethylthiourea inhibited the protective effects of RIPC. In contrast, there was no effect of hexamethonium on the protective effect of RIPC. CONCLUSIONS: An initial oxidative stress acts as a trigger to upregulate antioxidant enzyme activity, rather than the neural pathway, and plays an important role in the formation of the tolerance against spinal cord ischemia by limb RIPC.