Hypoxic preconditioning stimulates angiogenesis in ischemic penumbra after acute cerebral infarction

Previous studies have demonstrated the protective effect of hypoxic preconditioning on acute cerebral infarction, but the mechanisms underlying this protection remain unclear. To investigate the protective mechanisms of hypoxic preconditioning in relation to its effects on angiogenesis, we in- duced a photochemical model of cerebral infarction in an inbred line of mice （BALB/c）. Mice were then exposed to hypoxic preconditioning 30 minutes prior to model establishment. Results showed significantly increased vascular endothelial growth factor and CD31 expression in the ischemic penumbra at 24 and 72 hours post infarction, mainly in neurons and vascular endothelial cells. Hypoxic preconditioning increased vascular endothelial growth factor and CD31 expression in the ischemic penumbra and the expression of vascular endothelial growth factor was positively related to that of CD31. Moreover, hypoxic preconditioning reduced the infarct volume and improved neu- rological function in mice. These findings indicate that the protective role of hypoxic preconditioning in acute cerebral infarction may possibly be due to an increase in expression of vascular endothelial growth factor and CD31 in the ischemic penumbra, which promoted angiogenesis.

Impact of hypoxic preconditioning on apoptosis and its possible mechanism in orthotopic liver autotransplantation in rats

BACKGROUND: Hepatocyte apoptosis is a severe form of cell death after hepatic ischemia-reperfusion injury (HIRI), and its relief is an important issue in liver transplantation. Hypoxic preconditioning (HP) is considered to have protective effects on HIRI. This study was designed to explore the impact of HP on apoptosis and its possible mechanism during orthotopic liver autotransplantation. METHODS: A modified orthotopic liver autotransplantation model was used to simulate HIRI. Sprague-Dawley rats were randomly divided into normal control, autotransplantation (AT) and HP groups. The HP group was subjected to an 8% oxygen atmosphere for 90 minutes before surgery. At 1, 6 and 24 hours after surgery, the rats were killed and their liver tissue was sampled to assess the expression of Bcl-2 protein. The samples were subjected to blood chemistry study, morphological study under a light or transmission electron microscope, and quantitative study of mitochondria. RESULTS: The serum levels of ALT and AST in the HP group were lower than those in the AT group at 1, 6 and 24 hours after orthotopic liver autotransplantation (P < 0.05). Bcl-2 protein expression was increased in the HP group at each measurement point (P < 0.05). Light microscopy showed that hepatic injury in the AT group was much more severe than in the HP group. Hepatocytes in the AT group showed typical apoptosis signs under a transmission electron microscope. The ultrastructural appearance of hepatocytes in the HP group was much better than in the AT group, and the area, perimeter and diameter of the mitochondria were smaller in the HP group than in the AT group (P < 0.05). CONCLUSIONS: Hepatocytes sense and respond to decreased tissue oxygenation. Stimulation by HP relieves apoptosis by upregulating expression of Bcl-2 protein and its protection of mitochondria after orthotopic liver autotransplantation.

Effect of Hypoxic Preconditioning on Neural Cell Apoptosis and Expression of Bcl-2 and Bax in Cerebral Ischemia-Reperfusion in Rats

In order to investigate the protective effect of hypoxic preconditioning on the cerebral ischemia-reperfusion injury, the expression of Bcl-2 and Bax was detected by using immunohistochemical staining after 3 h cerebral ischemia followed by 1, 6, 12, 24 and 48 h reperfusion respectively in rats treated with or without hypoxic preconditioning before cerebral ischemia. In addition, the apoptosis of neural cells and the behavioral scores for neurological functions recovery were evaluated by TUNEL staining and ＂crawling method＂, respectively. Compared with control group （cerebral ischemia-reperfusion without hypoxic preconditioning）, the expression of Bcl-2 was significantly increased, but that of Bax decreased in the hypoxic preconditioning group （cerebral ischemiareperfusion with hypoxie preconditioning）, both P〈0.05. The pre-treatment with hypoxic preconditioning could reduce the apoptosis of neural cells and promote the neurological function recovery as compared to control group. It was suggested that hypoxic preconditioning may have protective effects on the cerebral ischemia-reperfusion injury by inhibiting the apoptosis of neural cells, increase the expression of Bcl-2 and decrease the expression of Bax.

Hypoxic preconditioning reduces NLRP3 inflammasome expression and protects against cerebral ischemia/reperfusion injury

Hypoxic preconditioning can protect against cerebral ischemia/reperfusion injury. However, the underlying mechanisms that mediate this effect are not completely clear. In this study, mice were pretreated with continuous, intermittent hypoxic preconditioning;1 hour later, cerebral ischemia/reperfusion models were generated by middle cerebral artery occlusion and reperfusion. Compared with control mice, mice with cerebral ischemia/reperfusion injury showed increased Bederson neurological function scores, significantly increased cerebral infarction volume, obvious pathological damage to the hippocampus, significantly increased apoptosis;upregulated interleukin-1β, interleukin-6, and interleukin-8 levels in brain tissue;and increased expression levels of NOD-like receptor family pyrin domain containing 3(NLRP3), NLRP inflammasome-related protein caspase-1, and gasdermin D. However, hypoxic preconditioning significantly inhibited the above phenomena. Taken together, these data suggest that hypoxic preconditioning mitigates cerebral ischemia/reperfusion injury in mice by reducing NLRP3 inflammasome expression. This study was approved by the Medical Ethics Committee of the Fourth Hospital of Baotou, China(approval No. DWLL2019001) in November 2019.

Gene expression changes after hypoxic preconditioning in rat hepatocytes

BACKGROUND: Hypoxic preconditioning can protect hepatocytes against hypoxic injury, but its mechanism has not been elucidated. The aim of this study was to profile gene expression patterns involved in hypoxic preconditioning and probable mechanism at the level of gene expression. METHODS: Hepatocytes were divided into 2 groups: control group and hypoxic preconditioning group. Biotinlabeled cRNA from the control group and the hypoxic preconditioning group was hybridized by oligonucleotide microarray. Genes that were significantly associated with hypoxic preconditioning were filtered, and validated at the level of transcript expression. RESULTS: Forty-three genes with significantly altered expression patterns were discovered and most of them had not been previously reported. Among these genes,genes encoding superoxide dismutase 2 (SOD2)and interleukin 10 (IL-10) in the hypoxic preconditioning group were confirmed to be up-regulated with real-time quantitative PCR. CONCLUSIONS: Many cytokines are involved in hypoxic preconditioning and protect hepatocytes from hypoxiareoxygenation injury, and the increase of oxygen freeradical scavengers and anti-inflammatory factors may play a key role in this phenomenon. Diverse signal pathways are probably involved.

Cerebrospinal fluid from rats given hypoxic preconditioning protects neurons from oxygen-glucose deprivation-induced injury

Hypoxic preconditioning activates endogenous mechanisms that protect against cerebral isch- emic and hypoxic injury. To better understand these protective mechanisms, adult rats were housed in a hypoxic environment （8% 02/92% N2） for 3 hours, and then in a normal oxygen environment for 12 hours. Their cerebrospinal fluid was obtained to culture cortical neurons from newborn rats for 1 day, and then the neurons were exposed to oxygen-glucose deprivation for 1.5 hours. The cerebrospinal fluid from rats subjected to hypoxic preconditioning reduced oxygen-glucose deprivation-induced injury, increased survival rate, upregulated Bcl-2 expression and downregulated Bax expression in the cultured cortical neurons, compared with control. These results indicate that cerebrospinal fluid from rats given hypoxic preconditioning protects against oxygen-glucose deprivation-induced injury by affecting apoptosis-related protein expres- sion in neurons from newborn rats.

Hypoxic preconditioning：effect,mechanism and clinical implication(Part 1)

Hypoxic preconditioning(HPC) refers to exposure of organisms,systems,organs,tissues or cells to moderate hypoxia/ischemia that is able to result in a resistance to subsequent severe hypoxia/ischemia in tissues and cells.The effects exerted by HPC are well documented.The original local in situ(LiHPC) is now broadened to remote ectopic organs-tissues(ReHPC) and extended crossly to cross pluripotential HPC(CpHPC) induced by a variety of stresses other than hypoxia/ischemia,including cancer,for example.We developed a unique animal model of repetitive autohypoxia in adult mice,and studied systematically on the effects and mechanisms of HPC on the model in our laboratory since the early 1960 s.The tolerances to hypoxia and protection from injury increased significantly in this model.The adult mice behave like hypoxia-intolerant mammalian newborns and hypoxia-tolerant adult animals during their exposure to repetitive autohypoxia.The overall energy supply and demand decreased,the microorganization of the brain maintained and the spacial learning and memory ability improved but not impaired,the detrimental neurochemicals such as free radicals down-regulated and the beneficial neurochemicals such as adenosine(ADO) and antihypoxic gene(s)/factor(s)(AHGs/AHFs) up-regulated.Accordingly,we hypothesize that mechanisms for the tolerance / protective effects of HPC are fundamentally depending on energy saving and brain plasticity in particular.It is thought that these two major mechanisms are triggered by exposure to hypoxia/ischemia via oxygen sensing-transduction pathways and HIF-1 initiation cascades.We suggest that HPC is an intrinsic mechanism developed in biological evolution and is a novel potential strategy for fighting against hypoxia-ischemia and other stresses.Motivation of endogenous antihypoxic potential,activation of oxygen sensing- signal transduction systems and supplement of exogenous antihypoxic substances as well as development of HPC appliances and HPC medicines such as AHFs are encouraged based on our basic research on HPC.HPC may result in therapeutic augmentation of the endogenous cytoprotection in hypoxic-ischemic or suffering from other diseases' patients.Evolutionary consideration of HPC and clinical implications of HPC are both discussed to guide future research.The product of AHF is expected to be one of the most effective first aid medicines to rescue patients in critical condition.HPC is beginning to be used in surgery and is expected to be developed into a feasible adaptive medicine in the near future.

Hypoxic Preconditioning Eliminates Differences in the Innate Resistance of Rats to Severe Hypoxia

Hypoxic preconditioning is able to increase the body’s resistance to hypoxic/ischemic stress. Understanding how to apply the hypoxic response to initiate the protective mechanism of ischemic preconditioning is a high priority. However, the relationship between innate resistance to hypoxic stress and preconditioning efficiency of moderate hypoxia has been poorly studied. In our work, the efficiency of single moderate hypobaric hypoxia (HBH) for resistance to severe hypobaric hypoxia (SHBH) was studied on intact rats and those pre-tested under SHBH with low, intermediate and high resistance to hypoxia. HBH has a significant preconditioning action on the resistance to hypoxia over a wide range from 270 to 1464 s (4.5 to 24.5 min) and at the same time eliminates the differences in the endurance under SHBH between all rat groups. It is concluded that 1) HBH preconditioning efficiency does not depend on an innate resistance to SHBH and prior hypoxic experience of rats;and 2) the pretesting to severe hypoxia has no value for predicting the hypoxic preconditioning efficiency and study of adaptive mechanisms.

Hypoxic/ischemic preconditioning attenuate PKCδ-medi-ated injury in patients and mice with cerebral infarction

Objective:cerebral ischemic/hypox-ic preconditioning(I/HPC)is an endogenous strategy in which brief periods of sublethal ischemia/hypoxia render neural tissues resistant to subsequent ischemic/hypoxic damage.This phenomenon has been found in the brain,heart,liver,intestine,muscle,kidneys,and lung.How-ever,whether HPC has a protective effect on secondary cerebral ischemic injury or protein kinase Cδ(PKCδ)within ischemic patients and animal models is still un-clear.Methods:using a hypoxic preconditioned mouse model and a middle cerebral artery occlusion mouse mod-el,combined with 2,3,5-triphenyl tetrazolium chloride(TTC)staining,SDS-polyacrylamide gel electrophoresis(SDS-PAGE),and Western blot,we observed changes in infarction size,density,edema ratio,and changes in PKCδand membrane translocation within the ischemic cortex of the middle cerebral artery occlusion(MCAO)mice.Results:HPC can attenuate neurological deficits and cerebral ischemic injuries of mice following MCAO,including decreases in infarct size,edema ratio,densities of infarct area,and neuron loss.In addition,HPC inhib-its PKCδmembrane translocation in the penumbra of the MCAO-induced ischemic cortex.We found that admin-istration of PKCδ-specific inhibitor dV1-1 mimics the neuroprotective effects of HPC,and nonisoform-specif-ic activation of PKC can partially abolish HPC-induced neuroprotection.Ischemic preconditioning decreased the levels of PKCδin the serum of patients with cerebral in-farction and reduced the cerebral nerve damage caused by ischemia.Conclusion:hypoxic/ischemic precondi-tioning attenuates PKCδ-mediated injury in patients and mice.These findings enrich our understanding of the sig-nal transduction mechanism underlying cerebral HPC and provide clues to developing medicine against ischemia/hypoxia-induced cerebral injuries.

Hypoxic Preconditioning Improved Neuroprotective Effect of Bone Marrow-Mesenchymal Stem Cells Transplantation in Acute Glaucoma Models

This study explored the novel strategy of hypoxic preconditioning of Bone Marrow Mesenchymal Stem Cells (BM-MSCs) before intra vitreal transplantation to improve neuroprotective effects of Retinal Ganglion Cells (RGCs) in Acute Glaucoma Models. The methods of this research were isolated mesenchymal stem cells from the bone marrow of adult wild-type Sprague-Dawley (SD) rats. BM-MSCs were cultured under normoxic or hypoxic (1% oxygen for 24 hours) conditions. Normoxic or hypoxic BM-MSCs were transplanted intravitreally 1 week after ocular hypertension induction by acutely increasing IOP to 100 - 120 mmHg for 60 minutes. Rats were killed 4 weeks after transplanted. Apoptosis was examined by tunnel assay and expression Brn3b (Brn3b = RGCs marker) by immunohistochemical analysis of the retina. Results showed that transplantation of hypoxic preconditioning BM-MSCs in acute glaucoma models resulted in a significant apoptosis decreasing (p < 0.05) and an significant increasing in RGCs (p < 0.05), as well as enhanced mor-phologic and functional benefits of stem cell therapy versus normoxic BM-MSCs transplantation. Conclusions: Hypoxic preconditioning enhances the capacity of BM-MSCs transplantation to improve neuroprotective effects of RGCs in Acute Glaucoma Models.

Effects of hypoxic preconditioning on myocardial mitochondrial energy metabolism during acute hypoxia in rats

The effects of hypoxic preconditioning (HP) on the functions of myocardial mitochondria and ATP content were studiedin the rat. Rats were exposed to a simulated altitude of 4000m (with a barometric pressure of 43 kPa) for 1d. The myocardialmitochondrial respiratory function was determined with the Clark type O2 electrode, mitochondrial membrane fluidity (MMF) wasassayed with fluorescence polarizative method, and the myocardial content of ATP, ADP and AMP were measured with high performance liquid chromatography. It was found that after the administration of HP, the ATP content was increased from 31.89±2.42/mg·g-1 to 60. 55±3.52/mg·g-1 (P<0.01 ), mitochondrial respiratory control rate (RGR) was increased from 1.84 ±0.58 to4. 55 ± 0. 32 (P<0.01), MMF was significantly increased (P< 0.05) and the activities of FO F1 -ATPase and Na+ -K+ -ATPasewere increased by 66% and 25%, respectively. It is concluded that HP is efficacious to improve myocardial energy metabolismthrough the mechanism of the increase of mitochondrial membrane fluidity and the improvement of mitochondrial respiratory function.

P38MAPK磷酸化水平增高参与HPC降低MCAO所致小鼠缺血性脑损伤

目的探讨P38丝裂原激活蛋白激酶(P38 MAPK)磷酸化和蛋白表达水平在低氧预适应(HPC)降低脑中动脉阻塞(MCAO)所致缺血性脑损伤中的变化。方法利用已建小鼠HPC-MCAO模型,将健康雄性BALB/c小鼠随机分为常氧假手术(H0 Sham)、HPC假手术(H4 Sham)、常氧缺血(H0)和HPC缺血(H4)4组,应用2,3,5-氯化三苯基四氮唑(TTC)染色、N issl染色等方法观察脑损伤情况,应用W estern b lot并结合Gel Doc凝胶成像系统,定量检测小鼠脑组织内P38 MAPK磷酸化和蛋白表达水平的变化。结果HPC可明显减小MCAO所致的脑梗死体积(P<0.05)。与H0 sham相比,缺血组小鼠皮层缺血核心区和半影区P38 MAPK磷酸化水平显著升高(P<0.05,n=6),HPC可进一步增加缺血半影区和对侧皮层组织中P38 MAPK磷酸化水平(P<0.05,n=6)。各组间P38MAPK蛋白表达量水平无明显变化。结论P38 MAPK可能参与了HPC降低MCAO所致小鼠缺血性脑损伤的作用。

miRNA-21-5p is an important contributor to the promotion of injured peripheral nerve regeneration using hypoxia-pretreated bone marrow-derived neural crest cells

Our previous study found that rat bone marrow–derived neural crest cells(acting as Schwann cell progenitors)have the potential to promote long-distance nerve repair.Cell-based therapy can enhance peripheral nerve repair and regeneration through paracrine bioactive factors and intercellular communication.Nevertheless,the complex contributions of various types of soluble cytokines and extracellular vesicle cargos to the secretome remain unclear.To investigate the role of the secretome and extracellular vesicles in repairing damaged peripheral nerves,we collected conditioned culture medium from hypoxia-pretreated neural crest cells,and found that it significantly promoted the repair of sensory neurons damaged by oxygen-glucose deprivation.The mRNA expression of trophic factors was highly expressed in hypoxia-pretreated neural crest cells.We performed RNA sequencing and bioinformatics analysis and found that miR-21-5p was enriched in hypoxia-pretreated extracellular vesicles of neural crest cells.Subsequently,to further clarify the role of hypoxia-pretreated neural crest cell extracellular vesicles rich in miR-21-5p in axonal growth and regeneration of sensory neurons,we used a microfluidic axonal dissociation model of sensory neurons in vitro,and found that hypoxia-pretreated neural crest cell extracellular vesicles promoted axonal growth and regeneration of sensory neurons,which was greatly dependent on loaded miR-21-5p.Finally,we constructed a miR-21-5p-loaded neural conduit to repair the sciatic nerve defect in rats and found that the motor and sensory functions of injured rat hind limb,as well as muscle tissue morphology of the hind limbs,were obviously restored.These findings suggest that hypoxia-pretreated neural crest extracellular vesicles are natural nanoparticles rich in miRNA-21-5p.miRNA-21-5p is one of the main contributors to promoting nerve regeneration by the neural crest cell secretome.This helps to explain the mechanism of action of the secretome and extracellular vesicles of neural crest cells in repairing damaged peripheral nerves,and also promotes the application of miR-21-5p in tissue engineering regeneration medicine.

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

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

cPKCγ在HPC抗N2a细胞OGD损伤中作用及其分子机制

目的在离体细胞水平,探讨经典型蛋白激酶Cγ(cPKCγ)在低氧预适应(HPC)对抗小鼠成神经瘤细胞(N2a)氧糖剥夺(OGD)损伤中作用及其可能的细胞分子机制。方法建立N2a细胞HPC和OGD模型,用3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐(MTT)比色法、乳酸脱氢酶(LDH)漏出率、原位末端标记(TUNEL)和蛋白印迹(Western blot)几种方法,分别检测N2a细胞损伤、坏死、凋亡和自噬水平。结果 OGD 2和4 h可使N2a细胞的生存率显著降低、死亡率明显增高(P<0.05,n=6);HPC(20 min)明显改善OGD 3 h对N2a细胞的损伤作用,而cPKCγ抑制剂Go6983(6 nmol/L)则显著解除HPC对OGD细胞的保护作用(P<0.05,n=16);OGD 3 h明显增加N2a细胞的凋亡数目(P<0.05,n=6),但HPC和Go6983+HPC均不能明显影响OGD细胞凋亡水平;OGD 3 h显著提高N2a细胞的自噬水平,Go6983和HPC+Go6983均可明显降低OGD细胞的自噬水平(P<0.05,n=6),而HPC则对OGD细胞的自噬水平无明显影响;HPC明显改善OGD 3 h致N2a细胞坏死的程度,而Go6983则可解除HPC的保护作用(P<0.05,n=16)。结论在离体细胞水平证实了cPKCγ在HPC改善N2a细胞OGD损伤中的作用,且这种作用主要与降低OGD细胞的坏死水平有关。

Hypoxia preconditioning protects Ca^(2+)-ATPase activation of intestinal mucosal cells against R/I injury in a rat liver transplantation model

AIM To investigate the effect of ischaemia and reperfusion(I/R) injury on the Ca^(2+)-ATPase activation in the intestinal tissue of a rat autologous orthotopic liver transplantation model and to determine if hypoxia preconditioning(HP) therapy induces HIF-1α to protect rat intestinal tissue against I/R injury.METHODS Rats received non-lethal hypoxic preconditioning therapy to induce HIF-1α expression. We used an autologous orthotopic liver transplantation model to imitate the I/R injury in intestinal tissue. Then, we detected the microstructure changes in small intestinal tissues, Ca^(2+)-ATPase activity, apoptosis, and inflammation within 48 h postoperatively. RESULTS HIF-1α expression was significantly increased in intestinal tissue at 12 h postoperatively in rats that were exposed to a hypoxic environment for 90 min compared with a non-HP group(HP vs AT, P = 0.0177). Pathological analysis was performed on the intestinal mucosa cells, and the cells in the HP group appeared healthier than the cells in the AT group. The Ca^(2+)-ATPase activity in the small intestinal cells in the AT group was significantly lower after the operation, and the Ca^(2+)-ATPase activity in the HP group recovered faster than that in the AT group at 6 h postoperatively(HP vs AT, P = 0.0106). BCL-2 expression in the HP group was significantly higher than that in the AT group at 12 h postoperatively(HP vs AT P = 0.0010). The expression of the inflammatory factors NO, SOD, IL-6, and TNF-α was significantly lower in the HP group than in the AT group.CONCLUSION Hypoxia-induced HIF-1α could protect intestinal mucosal cells against mitochondrial damage after I/R injury. HP could improve hypoxia tolerance in small intestinal mucosal cells and increase Ca^(2+)-ATPase activity to reduce the apoptosis of and pathological damage to intestinal cells. HP could be a useful way to promote the earlier recovery of intestinal function after graft procedure.

低氧预适应对魁蚶在低氧胁迫下生理生化指标的影响

本研究以未进行低氧预适应的魁蚶(Scapharcabroughtonii)为对照组(C组),分析了2次低氧预适应(H2组)和4次低氧预适应(H4组)的魁蚶在溶解氧(DO)约为2.0mg/L低氧胁迫48h内的摄食、呼吸代谢和酶活力的变化规律。结果显示,3组魁蚶的摄食率(IR)在胁迫初期急剧下降,后期均随时间的延长逐渐恢复,至48 h时,H组恢复程度显著高于C组(P<0.05);C组、H2组和H4组魁蚶的耗氧率(OR)随时间变化呈逐渐升高的趋势,48 h比0 h分别提高了1.15、1.08、0.73倍;3组排氨率(NR)表现出不同的变化趋势,至48h时,C组、H2组和H4组分别为0h的1.67、1.30、0.97倍;C组的氧氮比(O/N)相对平稳,H组的变化范围相对较大。3组的细胞色素C氧化酶(COX)随着低氧胁迫时间的延长呈逐渐降低的趋势,乳酸脱氢酶(LDH)活力和还原型谷胱甘肽酶(GSH)含量整体呈上升趋势,与对照组相比,预低氧组的酶活力在低氧胁迫期间变化相对平稳,应激反应小。研究表明,魁蚶经低氧预适应后再次受到低氧胁迫时,IR升高,OR降低,酶活性相对稳定,低氧预适应能提高魁蚶的耐低氧能力。本研究丰富了魁蚶低氧耐受相关研究的基础数据,为进一步探讨魁蚶低氧耐受机制和创制耐低氧新种质提供了参考资料。

低氧预处理脐带间充质干细胞源外泌体抑制肺动脉平滑肌细胞的增殖

背景:已有研究表明外泌体可以改善低氧性肺动脉高压,而且不同来源、不同环境的外泌体功能存在显著差别。低氧预处理脐带间充质干细胞来源外泌体对大鼠肺动脉平滑肌细胞增殖的影响尚不清楚。目的:探讨低氧预处理人脐带间充质干细胞来源外泌体对低氧诱导的大鼠肺动脉平滑肌细胞增殖的影响。方法:采用组织贴壁法分离培养原代人脐带间充质干细胞,用超滤法提取人脐带间充质干细胞来源外泌体;采用组织消化法分离大鼠肺动脉平滑肌细胞,用CCK-8法测定不同质量浓度外泌体干预肺动脉平滑肌细胞不同时间后的细胞增殖抑制率,确定外泌体作用的适宜质量浓度和干预时间。将第3代肺动脉平滑肌细胞分为常氧对照组、低氧对照组、低氧+常氧外泌体处理组和低氧+低氧外泌体处理组,EdU法检测各组细胞增殖情况,Western blot检测各组细胞核增殖抗原蛋白表达水平。结果与结论:①与常氧对照组相比,低氧对照组肺动脉平滑肌细胞增殖能力明显增加;与低氧对照组相比,低氧+常氧外泌体组细胞增殖能力下降,且低氧+低氧外泌体组增殖能力下降更明显;②与常氧对照组相比,低氧对照组细胞的细胞核增殖抗原蛋白表达升高;与低氧对照组相比,低氧+常氧外泌体组细胞核增殖抗原蛋白表达水平稍微降低,低氧+低氧外泌体组细胞核增殖抗原蛋白表达水平明显降低;③结果表明,低氧预处理人脐带间充质干细胞来源外泌体具有抑制肺动脉平滑肌细胞增殖的能力。

运动预适应介导氧化应激调控PI3K/Akt和Nrf2/HO-1通路对大鼠认知和学习障碍的影响

目的:探究运动预适应调控PI3K/Akt、Nrf2/HO-1信号通路和氧化应激减轻低氧暴露大鼠认知、学习障碍的基本机制。方法:将60只6周龄SPF级雄性SD大鼠,按照随机数字表法分为对照组、运动组、暴露组和运动+暴露组,每组15只。对照组和暴露组不进行运动预适应干预,运动组与运动+暴露组接受运动预处理干预(跑台训练,2次/d,6 d/周,共训练4周);运动预适应结束次日,暴露组和运动+暴露组大鼠接受7 d低氧暴露。7 d低氧暴露后,采用旷场实验及Morris水迷宫实验评估大鼠认知、学习能力;采用酶联免疫吸附测定法(ELISA)检测大鼠血清SOD、GSH活性,MDA含量和IL-1β、IL-6、TNF-α水平;通过尼氏染色观察海马CA1区尼氏小体变化;RT-PCR检测PI3K、Nox1、Duox2、Akt mRNA相对表达水平;采用Western blot法检测海马组织Nox1、Duox2、GCLM蛋白及PI3K/Akt、Nrf2/HO-1通路蛋白相对表达量。结果:与对照组和运动组比较,暴露组3 d逃避潜伏期上升(P<0.05),穿越平台次数和平台所在象限停留时间明显降低(P<0.05);血清MDA含量,IL-1β、IL-6、TNF-α水平均明显上升(P<0.05),SOD、GSH活性明显下降(P<0.05);CA1区尼氏小体数量下降(P<0.05);PI3K、Nox1、Duox2 mRNA相对表达水平上升(P<0.05),同时Akt mRNA相对表达水平下降(P<0.05);海马组织Nox1、Duox2、GCLM蛋白相对表达量显著上升(P<0.05),p-PI3K/PI3K、p-Akt/Akt、p-GSK-3β/GSK-3β比值和Nrf2、HO-1蛋白相对表达量明显下调(P<0.05)。与暴露组比较,运动+暴露组中心区域活动时间、3 d逃避潜伏期降低(P<0.05),穿越平台次数和平台所在象限停留时间上升(P<0.05);血清MDA含量,IL-1β、IL-6、TNF-α水平均明显下降(P<0.05),SOD、GSH活性明显上升(P<0.05);CA1区神经元损伤减轻,尼氏小体数量上升;海马组织PI3K、Nox1、Duox2 mRNA相对表达水平下降(P<0.05),Akt mRNA相对表达水平上升(P<0.05);海马组织Nox1、Duox2、GCLM蛋白相对表达量明显降低(P<0.05),p-PI3K/PI3K、p-Akt/Akt、p-GSK-3β/GSK-3β比值和Nrf2、HO-1蛋白相对表达量明显上升(P<0.05)。结论:运动预适应可能通过激活PI3K/Akt和Nrf2/HO-1信号通路参与调节脑组织氧化应激并减轻损伤程度,进而改善低氧暴露大鼠神经行为功能。

低氧运动预适应激活自噬调控Hippo/YAP/TAZ信号通路减轻急性低氧力竭运动大鼠骨骼肌损伤

目的:探讨低氧运动预适应激活自噬调控Hippo/YAP/TAZ信号通路对急性低氧力竭运动大鼠骨骼肌保护的机制。方法:50只6周龄SPF级雄性SD大鼠,随机分为空白对照组(Con组,n=10)、单纯急性低氧力竭运动组(HE组,n=10)、低氧预适应+急性低氧力竭运动组(HP+HE组,n=10)、运动预适应+急性低氧力竭运动组(EP+HE组,n=10)、低氧预适应+运动预适应+急性低氧力竭运动组(EP/HP+HE组,n=10)。预适应周期2 w, EP+HE组及EP/HP+HE组进行2次/d常压常氧跑台训练;HP+HE组及EP/HP+HE组进行10 h/d间歇性低氧暴露(FiO213.5%)。预适应后HE组、HP+HE组、EP+HE组及EP/HP+HE组大鼠进行低氧环境跑台力竭训练(FiO211.9%~12.0%)。低氧力竭运动后2 h,尾静脉取血检测血清骨骼肌损伤、炎症反应和氧化应激指标,苏木精-伊红染色观察腓肠肌病理特征,并检测腓肠肌自噬相关蛋白、Hippo/YAP/TAZ信号通路蛋白及mRNA。结果:(1)与HE组比较,预适应组大鼠低氧力竭运动后的腓肠肌结构损伤、炎症反应和氧化应激明显减轻。(2)HE组Atg5、Beclin1蛋白表达显著低于EP+HE组及EP/HP+HE组(P<0.05),EP/HP+HE组Atg5、Beclin1蛋白表达显著高于HP+HE组(P<0.05);HE组LC3-Ⅱ蛋白表达显著高于EP+HE组及EP/HP+HE组(P<0.05),EP+HE组及EP/HP+HE组显著高于HP+HE组(P<0.05)。(3)HE组MST1 mRNA显著高于EP+HE组及EP/HP+HE组(P<0.05),EP+HE组及EP/HP+HE组显著高于HP+HE组(P<0.05);HE组LATS1 mRNA显著低于预适应组(P<0.05);HE组YAP mRNA显著高于预适应组(P<0.05),EP/HP+HE组显著低于HP+HE组(P<0.05);HE组及HP+HE TAZ mRNA显著高于EP+HE组及EP/HP+HE组均显著降低(P<0.05)。(4)HE组MST1、LATS1及其磷酸化水平显著低于EP+HE组及EP/HP+HE组(P<0.05),EP/HP+HE组MST1显著高于HP+HE组(P<0.05);HE组YAP蛋白显著高于EP+HE组及EP/HP+HE组(P<0.05);HE组TAZ蛋白显著高于预适应组均显著降低(P<0.05),EP/HP+HE组均显著低于HP+HE组(P<0.05)。结论:低氧运动预适应可能通过激活骨骼肌自噬抑制Hippo/YAP/TAZ信号通路减轻急性低氧力竭运动大鼠的骨骼肌损伤、炎症反应和氧化应激反应。