Effect Of Hypoxic Preconditioning Research Articles

Potential for use of hypoxic preconditioning in aviation medicine

The paper evaluates Russian and foreign literature on the positive effects of dosed hypoxia on human body in the setting of training stimulation. This model can serve as a theoretical basis for the development of a hypoxic preconditioning technique, which can be extremely useful for air medical officers to maintain the professional health of pilots in modern conditions. The aim of this review was to inform a wide range of stakeholders about the various effects of hypoxic preconditioning, including cardioprotective, neuroprotective and vasoprotective effects. Existing hypoxic training techniques were reviewed, especially the advantages of normobaric hypoxic training to improve the functional status of pilots. The main advantages of this technique include possibility of wide use on flat terrain, the absence of changes in atmospheric pressure during training, no need for specially trained personnel and special premises, the possibility of selecting an individual training program, combination of hypoxic training with everyday tasks, minimal side effects, and long-term maintenance of training results. The mechanisms underlying hypoxic preconditioning are discussed, including the activation of genes encoding proteins involved in the regulation of oxygen homeostasis. The latest research data in hypoxic training are described. The paper also addresses issues that are not generally understood by practitioners who use hypoxia for therapeutic and preventive purposes (effectiveness of different techniques, role of blood saturation levels during hypoxic training, difference between preconditioning and postconditioning, and other aspects of practical hypoxic therapy). All these questions need to be answered in the near future in order to better understand the activation of human internal defense mechanisms by non-drug methods. Further studies are needed to determine the optimal preconditioning technique, including the duration and intensity of hypoxia exposure.

Postnatal hypoxic preconditioning attenuates lung damage from hyperoxia in newborn mice.

Preterm infants frequently require oxygen supplementation at birth. However, preterm lung is especially sensible to structural and functional damage caused by oxygen free radicals. The adaptive mechanisms implied in the fetal-neonatal transition from a lower to a higher oxygen environment were evaluated in a murine model using a custom-designed oxy-chamber. Pregnant mice were randomly assigned to deliver in 14% (hypoxic preconditioning group) or 21% (normoxic group) oxygen environment. Eight hours after birth FiO2 was increased to 100% for 60 min and then switched to 21% in both groups. A control group remained in 21% oxygen throughout the study. Mice in the normoxic group exhibited thinning of the alveolar septa, increased cell death, increased vascular damage, and decreased synthesis of pulmonary surfactant. However, lung histology, lamellar bodies microstructure, and surfactant integrity were preserved in the hypoxic preconditioning group after the hyperoxic insult. Postnatal hyperoxia has detrimental effects on lung structure and function when preceded by normoxia compared to controls. However, postnatal hypoxic preconditioning mitigates lung damage caused by a hyperoxic insult. Hypoxic preconditioning, implemented shortly after birth mitigates lung damage caused by postnatal supplemental oxygenation. The study introduces an experimental mice model to investigate the effects of hypoxic preconditioning and its effects on lung development. This model enables researchers to delve into the intricate processes involved in postnatal lung maturation. Our findings suggest that hypoxic preconditioning may reduce lung parenchymal damage and increase pulmonary surfactant synthesis in reoxygenation strategies during postnatal care.

Hypoxia preconditioning increases Notch1 activity by regulating DNA methylation in vitro and in vivo.

Our previous research has demonstrated that hypoxic preconditioning (HPC) can improve spatial learning and memory abilities in adult mice. Adult hippocampal neurogenesis has been associated with learning and memory. The Neurogenic locus notch homolog protein (Notch) was involved in adult hippocampal neurogenesis, as well as in learning and memory. It is currently unclear whether the Notch pathway regulates hippocampal neuroregeneration by modifying the DNA methylation status of the Notch gene following HPC. The HPC animal model and cell model were established through repeated hypoxia exposure using mice and the mouse hippocampal neuronal cell line HT22. Step-down test was conducted on HPC mice. Real-time PCR and Western blot analysis were used to assess the mRNA and protein expression levels of Notch1 and hairy and enhancer of split1 (HES1). The presence of BrdU-positive cells and Notch1 expression in the hippocampal dental gyrus (DG) were examined with confocal microscopy. The methylation status of the Notch1 was analyzed using methylation-specific PCR (MS-PCR). HT22 cells were employed to elucidate the impact of HPC on Notch1 in vitro. HPC significantly improved the step-down test performance of mice with elevated levels of mRNA and protein expression of Notch1 and HES1 (P < 0.05). The intensities of the Notch1 signal in the control group, the H group and the HPC group were 2.62 ± 0.57 × 107, 2.87 ± 0.84 × 107, and 3.32 ± 0.14 × 107, respectively, and the number of BrdU (+) cells in the hippocampal DG were 1.83 ± 0.54, 3.71 ± 0.64, and 7.29 ± 0.68 respectively. Compared with that in C and H group, the intensity of the Notch1 signal and the number of BrdU (+) cells increased significantly in HPC group (P < 0.05). The methylation levels of the Notch1 promoter 0.82 ± 0.03, 0.65 ± 0.03, and 0.60 ± 0.02 in the C, H, and HPC groups, respectively. The methylation levels of Notch1 decreased significantly (P < 0.05). The effect of HPC on HT22 cells exhibited similarities to that observed in the hippocampus. HPC may confer neuroprotection by activating the Notch1 signaling pathway and regulating its methylation level, resulting in the regeneration of hippocampal neurons.

Hypoxia preconditioning of human amniotic mesenchymal stem cells enhances proliferation and migration and promotes their homing via the HGF/C-MET signaling axis to augment the repair of acute liver failure

BackgroundTransplantation of mesenchymal stem cells (MSCs) is a newly developed strategy for treating acute liver failure (ALF). Nonetheless, the low survival rate of MSCs after transplantation and their poor homing to damaged tissues limit the clinical application of MSCs. The research assessed whether hypoxic preconditioning (HPC) can improve the biological activity of human amniotic mesenchymal stem cells (hA-MSCs), promote their homing ability to the liver of mice with ALF, and influence liver tissue repair. MethodsFlow cytometry, CCK8, Transwell, and Western blotting assays were conducted to assess the effects of hypoxic preconditioning on the phenotype, proliferation, and migration of hA-MSCs and the changes in the c-Met and CXCR4 gene expression levels were studied. To evaluate the effects of the transplantation of hypoxic preconditioning of hA-MSCs on the homing and repair of D-galactosamine (D-GalN)/LPS-induced ALF, the mechanism was elucidated by adding c-Met, CXCR4-specific blockers (SU11274 and AMD3100). ResultsAfter hypoxia pretreatment (1% oxygen volume fraction), hA-MSCs maintained the morphological characteristics of adherence and vortex colony growth and showed high CD44, CD90, and CD105 and low CD31, CD34, and CD45 expression levels. Hypoxic preconditioning of hA-MSCs significantly increased their proliferation and migration and highly expressed the c-Met and CXCR4 genes. In vivo and in vitro, this migration-promoting effect was suppressed by the c-Met specific blocker SU11274. In the acute liver failure mouse model, the HGF expression level was considerably elevated in the liver than that in the serum, lungs and kidneys. The transplantation of hypoxic preconditioned hA-MSCs introduced a remarkable improvement in the liver function and survival rate of mice with ALF and enhanced the anti-apoptosis ability of liver cells. The anti-apoptotic enhancing effect of hypoxic preconditioning was suppressed by the c-Met specific blocker SU11274. Hypoxic hA-MSCs administration was observed to have considerably increased the fluorescent cells in the liver than that recorded after administering normal oxygen-hA-MSCs. The number of hepatic fluorescent cells decreased remarkably after adding the c-Met inhibitor SU11274, compared to that recorded after hypoxic pretreatment, whereas the effect of c-Met inhibitor SU11274 on normal oxygen-hA-MSCs was not significant. ConclusionsHypoxic preconditioning depicted no impact on the morphology and phenotype features of the human amniotic mesenchymal stem cells, but it can promote their proliferation, migration, anti-apoptotic effect, and homing rate and improve the repair of acute liver failure, which might be mediated by the HGF/c-Met signaling axis.

Positive effects of hypoxic preconditioning of the extracellular matrix and stromal vascular fraction from adipose tissue

BackgroundNumerous approaches have been developed to decelerate the aging process of facial skin. Synthetic fillers and cell-enriched fat grafts are the main procedures employed to fill wrinkles. ObjectiveThe aim of this study was to evaluate the in vitro and in vivo safety and efficiency of a new process developed by SYMBIOKEN: the AmeaCell, which facilitates the extraction of the stromal vascular fraction (SVF) and the associated hypoxia pre-conditioned matrix to promote fat graft survival. MethodsThe AmeaCell device allows the extraction from adipose tissue of SVF and pre-conditioned MatriCS and promotes a hypoxic environment. Experiments were carried out on human cells and then in mice. ResultsCharacterization of cells and MatriCS showed that after their extraction using the new process developed by SYMBIOKEN, the extracted cells expressed stem-cell markers. The presence of characteristic proteins and lipid fractions found in the adipose matrix were confirmed in MatriCS. Cobalt chloride treatment of the matrix using the AmeaCell device induced modifications in the matrix composition with a decrease in laminin and without collagen modification, both of which promote adhesion and differentiation of SVF or adipose-derived stromal cells. The combination of MatriCS and SVF (1 × 106 and 5 × 106, respectively) is safe and efficient to fill winkles induced by UVB irradiation. The cross-talk between MatriCS and SVF can act a durable filler compared to the filling performed using cells or matrix or fat alone, which need to be replaced frequently. ConclusionThese results indicate that the combination of MatriCS and SVF is safe and effective as a biological filler for achieving skin rejuvenation and wrinkle filling.

The ischaemic preconditioning paradox and its implications for islet isolation from heart-beating and non heart-beating donors

The impact of ischaemia can severely damage procured donor organs for transplantation. The pancreas, and pancreatic islets in particular, is one of the most sensitive tissues towards hypoxia. The present study was aimed to assess the effect of hypoxic preconditioning (HP) performed ex-vivo in islets isolated from heart-beating donor (HBD) and non heart-beating donor (NHBD) rats. After HP purified islets were cultured for 24 h in hypoxia followed by islet characterisation. Post-culture islet yields were significantly lower in sham-treated NHBD than in HBD. This difference was reduced when NHBD islets were preconditioned. Similar results were observed regarding viability, apoptosis and in vitro function. Reactive oxygen species generation after hypoxic culture was significantly enhanced in sham-treated NHBD than in HBD islets. Again, this difference could be diminished through HP. qRT-PCR revealed that HP decreases pro-apoptotic genes but increases HIF-1 and VEGF. However, the extent of reduction and augmentation was always substantially higher in preconditioned NHBD than in HBD islets. Our findings indicate a lower benefit of HBD islets from HP than NHBD islets. The ischaemic preconditioning paradox suggests that HP should be primarily applied to islets from marginal donors. This observation needs evaluation in human islets.

Attenuation of the cytoprotection induced by hypoxic preconditioning upon transfection with BNIP3-siRNA in human neuroblastoma SH-SY5Y cells

Purpose The aim of this study was to investigate the functional role of hypoxic preconditioning (HPC) in human neuroblastoma cells. Methods BNIP3 small-interfering RNA (BNIP3-siRNA) sequence was synthesized and used to transfect human neuroblastoma SH-SY5Y cell lines. Thereafter, BNIP3 expression at mRNA and protein levels and its effects on the cell proliferation were analyzed. The most effective pair of siRNA was selected to knockdown the expression level of BNIP3. Moreover, the effects of HPC on oxygen-glucose deprivation/reperfusion (OGD/R)-induced apoptosis and autophagy in SH-SY5Y cells were explored to further reveal the possible mechanisms underlying HPC. Results BNIP3-siRNA attenuated the protective effects of HPC by decreasing the cell viability, increasing the enzymatic activity of caspase-3 and 9, increasing the rate of apoptosis, and increasing the protein expression level of activated caspase-3. Additionally, BNIP3-siRNA had no significant influence on the expression level of HIF-1α induced by HPC, while it substantially inhibited HPC-induced BNIP3/Beclin1 and autophagy. Conclusions HPC promoted autophagy through regulating BNIP3 to reduce OGD/R.

Effect of Hypoxic Preconditioning on Angiogenesis and Senescence in Human Adipose Tissue-Derived Mesenchymal Stem Cells

Effect of Hypoxic Preconditioning on Angiogenesis and Senescence in Human Adipose Tissue-Derived Mesenchymal Stem Cells

Whole body hypoxic preconditioning-mediated multiorgan protection in db/db mice via nitric oxide-BDNF-GSK-3β-Nrf2 signaling pathway.

The beneficial effects of hypoxic preconditioning are abolished in the diabetes. The present study was designed to investigate the protective effects and mechanisms of repeated episodes of whole body hypoxic preconditioning (WBHP) in db/db mice. The protective effects of preconditioning were explored on diabetes-induced vascular dysfunction, cognitive impairment and ischemia-reperfusion (IR)-induced increase in myocardial injury. Sixteen-week old db/db (diabetic) and C57BL/6 (non-diabetic) mice were employed. There was a significant impairment in cognitive function (Morris Water Maze test), endothelial function (acetylcholine-induced relaxation in aortic rings) and a significant increase in IR-induced heart injury (Langendorff apparatus) in db/db mice. WBHP stimulus was given by exposing mice to four alternate cycles of low (8%) and normal air O2 for 10 min each. A single episode of WBHP failed to produce protection; however, two and three episodes of WBHP significantly produced beneficial effects on the heart, brain and blood vessels. There was a significant increase in the levels of brain-derived neurotrophic factor (BDNF) and nitric oxide (NO) in response to 3 episodes of WBHP. Moreover, pretreatment with the BDNF receptor, TrkB antagonist (ANA-12) and NO synthase inhibitor (L-NAME) attenuated the protective effects imparted by three episodes of WBHP. These pharmacological agents abolished WBHP-induced restoration of p-GSK-3β/GSK-3β ratio and Nrf2 levels in IR-subjected hearts. It is concluded that repeated episodes of WHBP attenuate cognitive impairment, vascular dysfunction and enhancement in IR-induced myocardial injury in diabetic mice be due to increase in NO and BDNF levels that may eventually activate GSK-3β and Nrf2 signaling pathway to confer protection.

The role of reactive oxygen species in the infarct-limiting effect of hypoxic preconditioning

Introduction. Increased resistance of the heart to ischemia/reperfusion (I/R) is an urgent aim of physiology, pharmacology, and cardiac surgery, since I/R injury of the heart is often the cause of cardiogenic shock and subsequent death of patients in the postoperative period. Materials and methods. The study was carried out in male rats which were subjected to coronary artery occlusion (45 min) and reperfusion (2 h). Before coronary occlusion, early hypoxic preconditioning (HP) was modeled. The rats were subjected to six sessions of hypoxia (8 % O2, 10 min) and reoxygenation (21 % O2, 10 min) 30 min before coronary artery occlusion. The rats were injected with the following drugs: 1,3-dimethylthiourea (DMTM), 2-mercaptopropionyl glycine (2-MPG), deferoxamine. Results. It was found that HP contributes to infarct size reduction by 30 %. Preliminary administration of DMTM, 2-MPG, deferoxamine eliminated the infarct-reducing effect of HP. Conclisuon. The obtained data indicate that reactive oxygen species are involved in the cardioprotective effect of HP.

The Role of Reactive Oxygen Species and Opioid Receptors in the Infarct‐Reducing Effect of Hypoxic Preconditioning

An increase in cardiac resistance to ischemia/reperfusion (I/R) is an urgent aim of physiology, pharmacology, and cardiac surgery, since I/R injury of the heart is often the cause of cardiogenic shock and subsequent death of patients in the postoperative period. We have previously established that early hypoxic preconditioning has the infarct-limiting effect in rats. We hypothesized that reactive oxygen species (ROS) and opioid receptors (ORs) can be involved in this protective effect. The study was carried out in male Wistar rats which were subjected to coronary artery occlusion (45 min) and reperfusion (2 h). Before coronary occlusion, early hypoxic preconditioning (HP) was modeled. The rats were exposed to six sessions of hypoxia (8% O2, 10 min) and reoxygenation (21% O2, 10 min) 30 min before ischemia. The total duration of HP was 2 h. 2′,7′-dichlorodihydrofluorescein diacetate was used for the detection of free radicals in myocardial homogenates. Amplex Red was used for the detection of H2O2 in myocardial tissue. The rats were injected with the following compounds: a hydroxyl radical (OH•) scavenger 1,3-dimethylthiourea (DMTM), a non-selective OH• scavenger 2-mercaptopropionyl glycine (2-MPG), a Fe2+ chelator deferoxamine and the OR antagonist naltrexone. It was found that HP contributes to infarct size reduction by 30%. Preliminary administration of DMTM, 2-MPG, deferoxamine eliminated the infarction-limiting effect of HP. Naltrexone did not abolish the infarct-sparing effect of HP. These compounds did not affect the infarct size/area at risk ratio in non-preconditioned rats. The total ROS level was increased in the myocardium after HP by 2-fold. The H2O2 level was increased by about 10%. These data indicate that ROS are involved in the cardioprotective effect of HP. Opioid receptors are not involved in the infarct-limiting effect of HP.

Neuroprotective effect of hypoxic preconditioning and neuronal activation in a in vitro human model of the ischemic penumbra

Objective. In ischemic stroke, treatments to protect neurons from irreversible damage are urgently needed. Studies in animal models have shown that neuroprotective treatments targeting neuronal silencing improve brain recovery, but in clinical trials none of these were effective in patients. This failure of translation poses doubts on the real efficacy of treatments tested and on the validity of animal models for human stroke. Here, we established a human neuronal model of the ischemic penumbra by using human induced pluripotent stem cells and we provided an in-depth characterization of neuronal responses to hypoxia and treatment strategies at the network level.Approach. We generated neurons from induced pluripotent stem cells derived from healthy donor and we cultured them on micro-electrode arrays. We measured the electrophysiological activity of human neuronal networks under controlled hypoxic conditions. We tested the effect of different treatment strategies on neuronal network functionality.Main results. Human neuronal networks are vulnerable to hypoxia reflected by a decrease in activity and synchronicity under low oxygen conditions. We observe that full, partial or absent recovery depend on the timing of re-oxygenation and we provide a critical time threshold that, if crossed, is associated with irreversible impairments. We found that hypoxic preconditioning improves resistance to a second hypoxic insult. Finally, in contrast to previously tested, ineffective treatments, we show that stimulatory treatments counteracting neuronal silencing during hypoxia, such as optogenetic stimulation, are neuroprotective.Significance. We presented a human neuronal model of the ischemic penumbra and we provided insights that may offer the basis for novel therapeutic approaches for patients after stroke. The use of human neurons might improve drug discovery and translation of findings to patients and might open new perspectives for personalized investigations.

Effects of Hypoxic Preconditioning and Vascular Endothelial Growth Factor on the Survival of Isolated Primary Retinal Ganglion Cells.

This study aimed to investigate the effect of hypoxic preconditioning (HPC) on primary retinal ganglion cell (RGC) survival and the associated mechanism, including the role of vascular endothelial growth factor (VEGF). Retinas were separated from the enucleated eyeballs of Sprague–Dawley rats on postnatal days 1–4. RGCs were harvested using an immunopanning-magnetic separation system and maintained for 24 h in a defined medium. Hypoxic damage (0.3% O2) was inflicted on the cells using a CO₂ chamber. Anti-VEGF antibody (bevacizumab) was administered to RGCs exposed to hypoxic conditions, and RGC survival rate was compared to that of non-anti-VEGF antibody-treated RGCs. HPC lasting 4 h significantly increased RGC survival rate. In the RGCs exposed to hypoxic conditions for 4 h, VEGF mRNA and protein levels were significantly increased. Treatment with high dose bevacizumab (>1 mg/mL) countered HPC-mediated RGC survival. Protein kinase B and focal adhesion kinase levels were significantly increased in 4-h hypoxia-treated RGCs. HPC showed beneficial effects on primary RGC survival. However, only specifically controlled exposure to hypoxic conditions rendered neuroprotective effects. Strong inhibition of VEGF inhibited HPC-mediated RGC survival. These results indicate that VEGF may play an essential role in promoting cell survival under hypoxic conditions.

Hypoxia preconditioning improves structure and function of astrocytes mitochondria via PGC-1α/HIF signal

The protective effect of astrocytes on nerves was demonstrated by mitochondrial transfer. The neuroprotective effect of hypoxic pretreatment is widely accepted. The aim of this research is to investigate the role of hypoxic preconditioning on astrocytes mitochondria. Rat neuronal cells and astrocytes were isolated and cultured. A hypoxic preconditioned astrocyte and oxygen glucose deprivation (OGD) neuronal cell co-culture experiment was used to detect the effect of hypoxic preconditioning (HP) on nerve damage. The silencing of proliferatoractivated receptor γ coactivator-1α (PGC-1α) with siRNA was used to explore the role of HP in the repair of nerve damage and biogenesis of mitochondria. HP increased astrocyte viability and promoted neuroprotective factor secretion. The expression levels of antioxidant enzymes, PGC-1α and uncoupling protein2 (UCP2) were up-regulated by HP. In addition, HP improved mitochondrial function and reduced oxidative stress induced by OGD. It was found that HP astrocytes had a greater neuroprotective effect than normal astrocytes cells. Neuronal apoptosis and reactive oxygen species levels were down-regulated by cell co-culture. The PGC-1α siRNA experiment showed that hypoxia treatment promotes mitochondrial biogenesis and plays a neuroprotective role. HP significantly enhanced the efficacy of astrocytes in the treatment of neuronal injury.

BDNF Overexpression Enhances the Preconditioning Effect of Brief Episodes of Hypoxia, Promoting Survival of GABAergic Neurons

Hypoxia causes depression of synaptic plasticity, hyperexcitation of neuronal networks, and the death of specific populations of neurons. However, brief episodes of hypoxia can promote the adaptation of cells. Hypoxic preconditioning is well manifested in glutamatergic neurons, while this adaptive mechanism is virtually suppressed in GABAergic neurons. Here, we show that brain-derived neurotrophic factor (BDNF) overexpression in neurons enhances the preconditioning effect of brief episodes of hypoxia. The amplitudes of the NMDAR- and AMPAR-mediated Ca2+ responses of glutamatergic and GABAergic neurons gradually decreased after repetitive brief hypoxia/reoxygenation cycles in cell cultures transduced with the (AAV)-Syn-BDNF-EGFP virus construct. In contrast, the amplitudes of the responses of GABAergic neurons increased in non-transduced cultures after preconditioning. The decrease of the amplitudes in GABAergic neurons indicated the activation of mechanisms of hypoxic preconditioning. Preconditioning suppressed apoptotic or necrotic cell death. This effect was most pronounced in cultures with BDNF overexpression. Knockdown of BDNF abolished the effect of preconditioning and promoted the death of GABAergic neurons. Moreover, the expression of the anti-apoptotic genes Stat3, Socs3, and Bcl-xl substantially increased 24 h after hypoxic episodes in the transduced cultures compared to controls. The expression of genes encoding the pro-inflammatory cytokines IL-10 and IL-6 also increased. In turn, the expression of pro-apoptotic (Bax, Casp-3, and Fas) and pro-inflammatory (IL-1β and TNFα) genes decreased after hypoxic episodes in cultures with BDNF overexpression. Inhibition of vesicular BDNF release abolished its protective action targeting inhibition of the oxygen-glucose deprivation (OGD)-induced [Ca2+]i increase in GABAergic and glutamatergic neurons, thus promoting their death. Bafilomycin A1, Brefeldin A, and tetanus toxin suppressed vesicular release (including BDNF) and shifted the gene expression profile towards excitotoxicity, inflammation, and apoptosis. These inhibitors of vesicular release abolished the protective effects of hypoxic preconditioning in glutamatergic neurons 24 h after hypoxia/reoxygenation cycles. This finding indicates a significant contribution of vesicular BDNF release to the development of the mechanisms of hypoxic preconditioning. Thus, our results demonstrate that BDNF plays a pivotal role in the activation and enhancement of the preconditioning effect of brief episodes of hypoxia and promotes tolerance of the most vulnerable populations of GABAergic neurons to hypoxia/ischemia.

Molecular Mechanism Underlying Hypoxic Preconditioning-Promoted Mitochondrial Translocation of DJ-1 in Hypoxia/Reoxygenation H9c2 Cells.

DJ-1 was recently reported to be involved in the cardioprotection of hypoxic preconditioning (HPC) against hypoxia/reoxygenation (H/R)-induced oxidative stress damage, by preserving mitochondrial complex I activity and, subsequently, inhibiting mitochondrial reactive oxygen species (ROS) generation. However, the molecular mechanism by which HPC enables mitochondrial translocation of DJ-1, which has no mitochondria-targeting sequence, to preserve mitochondrial complex I, is largely unknown. In this study, co-immunoprecipitation data showed that DJ-1 was associated with glucose-regulated protein 75 (Grp75), and this association was significantly enhanced after HPC. Immunofluorescence imaging and Western blot analysis showed that HPC substantially enhanced the translocation of DJ-1 from cytosol to mitochondria in H9c2 cells subjected to H/R, which was mimicked by DJ-1 overexpression induced by pFlag-DJ-1 transfection. Importantly, knockdown of Grp75 markedly reduced the mitochondrial translocation of DJ-1 induced by HPC and pFlag-DJ-1 transfection. Moreover, HPC promoted the association of DJ-1 with mitochondrial complex I subunits ND1 and NDUFA4, improved complex I activity, and inhibited mitochondria-derived ROS production and subsequent oxidative stress damage after H/R, which was also mimicked by pFlag-DJ-1 transfection. Intriguingly, these effects of HPC and pFlag-DJ-1 transfection were also prevented by Grp75 knockdown. In conclusion, these results indicated that HPC promotes the translocation of DJ-1 from cytosol to mitochondria in a Grp75-dependent manner and Grp75 is required for DJ-1-mediated protection of HPC on H/R-induced mitochondrial complex I defect and subsequent oxidative stress damage.

Potential role of the cAMP/PKA/CREB signalling pathway in hypoxic preconditioning and effect on propofol‑induced neurotoxicity in the hippocampus of neonatal rats.

Hypoxic preconditioning (HPC) is neuroprotective against ischaemic brain injury; however, the roles of potential anti-apoptotic signals in this process have not been assessed. To elucidate the molecular mechanisms involved in HPC-induced neuroprotection, the effects of HPC on the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA)/cAMP response element-binding protein (CREB) signalling pathway and apoptosis in Sprague-Dawley pups (postnatal day 7) treated with propofol were investigated. Western blot and histological analyses demonstrated that HPC exerts multiple effects on the hippocampus, including the upregulation of cAMP and phosphorylation of CREB. These effects were partially blocked by intracerebroventricular injection of the protein kinase antagonist H89 (5 µmol/5 µl). Notably, the level of cleaved caspase-3 was significantly downregulated by treatment with the cAMP agonist Sp-cAMP (20 nmol/5 µl). The results indicate that propofol increased the level of cleaved caspase-3 and Bax by suppressing the activity of cAMP-dependent proteins and Bcl-2; thus, HPC prevents propofol from triggering apoptosis via the cAMP/PKA/CREB signalling pathway.

Cardioprotective Effect of the Adaptive Phenomenon of Early Hypoxic Preconditioning and Its Pharmacological Imitation

The roles of NO synthase and ATP-dependent K+ channels (KATP channels) in the development of the infarct-limiting effect of early hypoxic preconditioning (HP) in rats were studied and the potential for pharmacological simulation of this phenomenon was demonstrated. HP was modeled by alternation of six 10-min sessions of normobaric hypoxia (8% O2) and six 10-min periods of reoxygenation with atmospheric oxygen (21% O2). The total duration of the adaptive action was 120 min. These results indicate that NO synthase and KATP channels play the role of mediators in the signal mechanism of HP. NO donors and KATP channel activators allow the protective effect of hypoxic preconditioning to be reproduced by administration 1 h before ischemia/reperfusion but not when given 2 h 30 min before coronary occlusion.

PO-045 Effect of Hypoxic Pre-conditioning and Altitude Training on CD55 and CD59 Expressions of Swimmers

Objective By studying the swimmer after preconditioning during altitude training again after the change of erythrocyte immune and immune function, summarizes the change law of erythrocyte immune to try on erythrocyte immune to the connection between the immune index, further perfect the study on hypoxic training for athletes erythrocyte immune level, provide help and reference for scientific plateau training, comprehensive monitoring the immune function, so that more clear understanding of the athlete's body function condition, effective judgment level of fatigue, for the early diagnosis of overtraining and training plan of reasonable adjustment has important significance.&#x0D; Methods . Subjects: 8 first-line swimmers in Shanghai, aged 16.9 + 3.5 years. 2. Hypoxic training program: the 3-week hypoxic training was conducted in the east green boat hypoxic training laboratory with a starting height of 1500m and a height of 2200m after 3 days. Sleep from 19:00 PM to 6:00 am in the hypoxic laboratory six days a week. Day training in an aerobic environment. 3 days after the end of hypoxic training, I went to kunming (2,200m) for 3 weeks of altitude training. After the highland training, go to the field to prepare for the competition. 3. Test indicators: RBC immune indicators CD55,CD59; Functional status indicators RBC,HGB,HCT; Test time: 1 week before hypoxic start, 1 week before hypoxic start, 1 week after hypoxic end (i.e. before plateau training start), and 4 times of day elbow-venous blood taken at the end of altitude training was used for testing. P&lt;0.05 indicates a significant difference, while P&lt;0.01 indicates a very significant difference.&#x0D; Results It was founded that:1)The CD55 levels of the swimmers increased 0.56% at the 10th day,decreased 2.74% at the 3rd week and increased 9.89% 1 week after hypoxic pre-conditioning training. 2) The CD59 levels of the rowers revealed the similar changes as the CD55 during hypoxic pre-conditioning training. 3) The CD3 decreased by 4.13% and CD4/CD8 by 2.4% at the 1st week after hypoxic pre-conditioning training. 4)Compared with normal altitude training,CD55 and CD59 were kept in a high level in the third week of altitude training. CD59 of this week was lower than last two weeks.5 )WBC of the first hypoxic training week increased a little,and then,it come down in the next two weeks.In the third week of altitude training,WBC has gone up again.Three white cell subsets have different reaction.This result is similar with other researches.&#x0D; Conclusions These results suggest that the effect of our altitude training method takes a different stimulation compared with normal altitude training. Mainly presented: 1).The expressions of CD55 and CD59 increased after hypoxic pre-conditioning and altitude training. 2).The erythrocyte immunity was more sensitive to the hypoxic training. CD55 and CD59 kept in a high level in the third week of altitude training. CD3 increased also. These showed that three weeks hypoxic training accelerated the adaption to altitude training.It suggested that our method took good effects on improving physical functions in altitude training period.

Mutation in the Sip1 transcription factor leads to a disturbance of the preconditioning of AMPA receptors by episodes of hypoxia in neurons of the cerebral cortex due to changes in their activity and subunit composition. The protective effects of interleukin-10

The Sip1 mutation plays the main role in pathogenesis of the Mowat-Wilson syndrome, which is characterized by the pronounced epileptic symptoms. Cortical neurons of homozygous mice with Sip1 mutation are resistant to AMPA receptor activators. Disturbances of the excitatory signaling components are also observed on such a phenomenon of neuroplasticity as hypoxic preconditioning. In this work, the mechanisms of loss of the AMPA receptor's ability to precondition by episodes of short-term hypoxia were investigated on cortical neurons derived from the Sip1 homozygous mice. The preconditioning effect was estimated by the level of suppression of the AMPA receptors activity with hypoxia episodes. Using fluorescence microscopy, we have shown that cortical neurons from the Sip1fl/fl mice are characterized by the absence of hypoxic preconditioning effect, whereas the amplitude of Ca2+-responses to the application of the AMPA receptor agonist, 5-Fluorowillardiine, in neurons from the Sip1 mice brainstem is suppressed by brief episodes of hypoxia. The mechanism responsible for this process is hypoxia-induced desensitization of the AMPA receptors, which is absent in the cortex neurons possessing the Sip1 mutation. However, the appearance of preconditioning in these neurons can be induced by phosphoinositide-3-kinase activation with a selective activator or an anti-inflammatory cytokine interleukin-10.