Effects of Intermittent Hypoxia Exposure on Symptoms of Chronic Fatigue Syndrome in Repeated Restraint Stress and Forced Swimming Induced-Mouse Model

Background: Chronic fatigue syndrome (CFS) shows as its main symptoms debilitating fatigue that is not relieved by physiological rest, depression, inflammation, learning disability and memory impairment. But, intermittent hypoxia, consisting of alternating exposure to hypoxia and normoxia, plays a very important role in improving CFS. However, the essential components for improving learning and memory in CFS patients as well as their mechanism are largely unknown. Objectives: This study aims to analyze the effects of 12% and 15% hypoxia on the expression of alpha tumor necrosis factor (TNF-α) and nuclear factor kappa B (NF-κB) in CFS induced-mouse model for clarifying the effects on the learning and memory function. Methods: A total of 48 type IC mice were used. The CFS mouse model was established using restrained stress and repeated forced swimming. Treatment of CFS was done by exposing CFS mice to intermittent hypoxia at 12% and 15%. The effects of intermittent hypoxia on learning and memory as well as its mechanism of action on inflammation were tested respectively with the Morris test, the SDS page, the immunohistochemistry technique and the Nissl staining. Results: We found that 12% and 15% intermittent hypoxia exposure improved learning capacity and memory of CFS induced-mice. SDS page showed that CFS caused higher TNF-α expression. By exposing CFS mice to 12% and 15% intermittent hypoxia, TNF-α expression decreased significantly, with a much better effect at 15%. Both TNF-α and NF-κB increased in CFS state and decreased after treatment with intermittent hypoxia. Conclusion: Intermittent hypoxia improves learning capacity and memory. It acted by decreasing NF-κB come to down-regulating TNF-α and ameliorates learning capacity and memory impairment in CFS mice.

Novel Role of Calcium-Sensitive Receptors in Chronic Hypoxia-Induced Proliferation of Pulmonary Vein Smooth Muscle Cells

Objective:Vascular remodeling due to chronic hypoxia(CH)occurs not only in the pulmonary arteries but also in the pulmonary veins.Pulmonary vascular remodeling arises from the proliferation of pulmonary vascular myocytes.However,the mechanism by which CH induces the proliferation of pulmonary vein smooth muscle cells(PVSMCs)is unknown.This study aimed to investigate the mechanism by which CH affects the proliferation of PVSMCs.Methods:PVSMCs were isolated from rat distal pulmonary veins and exposed to CH(4%O2,60h),and the expression of the calcium-sensitive receptor(CaSR)was detected by Western blotting and immunofluorescence.MTT assay was used to detect the proliferation viability of the cells,and the changes in the intracellular calcium concentration were detected by laser confocal scanning technique.Results:CaSR expression was present in rat distal PVSMCs,and CaSR protein expression was upregulated under hypoxia.The positive regulator spermine not only enhanced CH-induced CaSR upregulation but also enhanced CH-induced increase in cell viability and calcium ion concentration.The negative CaSR regulator NPS2143 not only attenuated CH-induced CaSR upregulation but also inhibited CH-induced cell viability and calcium ion concentration.Conclusion:CaSR-mediated hyperproliferation is a novel pathogenic mechanism for the development of proliferation in distal PVSMCs under CH conditions.

Effect of NADPH Oxidase Inhibitor Apocynin on the Expression of Hypoxia-induced Factor-1α and Endothelin-1 in Rat Carotid Body Exposed to Chronic Intermittent Hypoxia

The effects of nicotinamide adenine dinucleotide phosphate （NADPH） oxidase inhibitor apocynin on the enhanced hypoxia induced factor-let （HIF-lct） and endothelin-1 （ET-1） expression, elevated systolic blood pressure under chronic intermittent hypoxia （CIH） condition and its action mechanism were investigated. Thirty healthy 8-week old Sprague-Dawley （SD） male rats were randomly divided into three groups （n=10 each）： sham group, CIH group, and apocynin-treated CIH group. Tail artery systolic blood pressure was measured by tail-cuff method. Real-time fluorescence quantitative polymerase chain reaction （PCR） was used to detect the mRNA expression of HIF-lu and ET-1 in the carotid body, and the HIF-1a protein expression was examined by using Western blotting. The levels of malondialdehyde （MDA） and superoxide dismutase （SOD） were determined by using colorimetric method. In addition, the plasma ET-1 and HIF-1a levels were measured by using enzyme-linked immunosorbent assay. It was found that CIH exposure was associated with increased MDA levels, and apo- cynin-treated CIH animals showed reduction in MDA levels. Apocynin treatment prevented CIH-induced hypertension as well as CIH-induced decrease in SOD. The increases of HIF-1a and ET-1 mRNA along with HIF-la protein expression in the carotid body, and elevated circulating HIF-1a and ET-1 levels were observed in CIH-exposed animals. Treatment with apocynin significantly decreased the ET-1 mRNA, HIF-lct protein expression and circulating HIF-la level in CIH-exposed animals, and there was no statistically significant difference in the HIF-lu mRNA expression between CIH group and apo- cynin-treated group. These results indicated that apocynin alleviated CIH-induced hypertension by inhibiting NADPH oxidase, further leading to the reduced vasoconstrictor ET-1 level and oxidative stress. HIF-1a/ET-1 system signal pathway may interact with CIH-induced NADPH oxidase-dependent oxidative stress. Inhibition of NADPH oxidase activity may hopefully serve as a useful strategy for prevention and treatment of obstructive sleep apnea hypopnea syndrome-induced hypertension.

Impairment of cognitive function and reduced hippocampal cholinergic activity in a rat model of chronic intermittent hypoxia

The present study established a rat model of chronic intermittent hypoxia （CIH） to simulate obstructive sleep apnea syndrome. CIH rats were evaluated for cognitive function using the Morris water maze, and neuronal pathology in the hippocampus was observed using hematoxylin-eosin staining. In addition, hippocampal choline acetyl transferase （CHAT） and nicotinic acetylcholine receptor （nAChR） expression was determined by immunohistochemistry. Our results revealed necrotic hippocampal neurons, decreased ChAT and nAChR expression, as well as cognitive impairment in CIH rats. These results suggest that hippocampal neuronal necrosis and decreased cholinerqic activity may be involved in CIH-induced cognitive impairment in rats.

Effects of hypoxia on bone metabolism and anemia in patients with chronic kidney disease

BACKGROUND Abnormal bone metabolism and renal anemia seriously affect the prognosis of patients with chronic kidney disease(CKD).Existing studies have mostly addressed the pathogenesis and treatment of bone metabolism abnormality and anemia in patients with CKD,but few have evaluated their mutual connection.Administration of exogenous erythropoietin to CKD patients with anemia used to be the mainstay of therapeutic approaches;however,with the availability of hypoxia-inducible factor(HIF)stabilizers such as roxadustat,more therapeutic choices for renal anemia are expected in the future.However,the effects posed by the hypoxic environment on both CKD complications remain incompletely understood.AIM To summarize the relationship between renal anemia and abnormal bone metabolism,and to discuss the influence of hypoxia on bone metabolism.METHODS CNKI and PubMed searches were performed using the key words“chronic kidney disease,”“abnormal bone metabolism,”“anemia,”“hypoxia,”and“HIF”to identify relevant articles published in multiple languages and fields.Reference lists from identified articles were reviewed to extract additional pertinent articles.Then we retrieved the Abstract and Introduction and searched the results from the literature,classified the extracted information,and summarized important information.Finally,we made our own conclusions.RESULTS There is a bidirectional relationship between renal anemia and abnormal bone metabolism.Abnormal vitamin D metabolism and hyperparathyroidism can affect bone metabolism,blood cell production,and survival rates through multiple pathways.Anemia will further attenuate the normal bone growth.The hypoxic environment regulates bone morphogenetic protein,vascular endothelial growth factor,and neuropilin-1,and affects osteoblast/osteoclast maturation and differentiation through bone metabolic changes.Hypoxia preconditioning of mesenchymal stem cells(MSCs)can enhance their paracrine effects and promote fracture healing.Concurrently,hypoxia reduces the inhibitory effect on osteocyte differentiation by inhibiting the expression of fibroblast growth factor 23.Hypoxia potentially improves bone metabolism,but it still carries potential risks.The optimal concentration and duration of hypoxia remain unclear.CONCLUSION There is a bidirectional relationship between renal anemia and abnormal bone metabolism.Hypoxia may improve bone metabolism but the concentration and duration of hypoxia remain unclear and need further study.

Short-term Chronic Intermittent Hypobaric Hypoxia Alters Gut Microbiota Composition in Rats

Chronic intermittent hypobaric hypoxia (CIHH) is a treatment of moderate hypoxia that simulates high altitude interrupted by normoxia. Growing evidence shows that CIHH has multiple beneficial effects on

Hypoxia,angiogenesis and liver fibrogenesis in the progression of chronic liver diseases

Angiogenesis is a dynamic,hypoxia-stimulated and growth factor-dependent process,and is currently referred to as the formation of new vessels from preexisting blood vessels.Experimental and clinical studies have unequivocally reported that hepatic angiogenesis,irrespective of aetiology,occurs in conditions of chronic liver diseases(CLDs) characterized by perpetuation of cell injury and death,inflammatory response and progressive fibrogenesis.Angiogenesis and related changes in liver vascular architecture,that in turn concur to increase vascular resistance and portal hypertension and to decrease parenchymal perfusion,have been proposed to favour fibrogenic progression of the disease towards the end-point of cirrhosis.Moreover,hepatic angiogenesis has also been proposed to modulate the genesis of portal-systemic shunts and increase splanchnic blood flow,thus potentially affecting complications of cirrhosis.Hepatic angiogenesis is also crucial for the growth and progression of hepatocellular carcinoma.Recent literature has identified a number of cellular and molecular mechanisms governing the cross-talk between angiogenesis and fibrogenesis,with a specifi c emphasis on the crucial role of hypoxic conditions and hepatic stellate cells,particularly when activated to the myofibroblast-like pro-fibrogenic.Experimental anti-angiogenic therapy has been proven to be effective in limiting the progression of CLDs in animal models.From a clinical point of view,anti-angiogenic therapy is currently emerging as a new pharmacologic intervention in patients with advanced fibrosis and cirrhosis.

Expression of RUNX2 and MDM21 in rats with periodontitis under chronic intermittent hypoxia

Objective: To discuss the expression of RUNX2 and MDM21 in rats with periodontitis under the chronic intermittent hypoxia. Methods: A total of 32 SD healthy rats were randomly divided into four groups, with 8 rats in each group. The molecular biological techniques of immunohistochemistry, RT-PCR and Western blotting were employed to detect the effect of different hypoxia time(0, 6, 12, 24 and 48 h) and different concentrations of hypoxia(0.000, 0.001, 0.010, 0.060 and 0.100 ppm) on the expression of RUNX2 and MDM21 in rats of four groups. Results: The expression of RUNX2 and MDM21 in each group was significantly higher than the one at other concentrations when the concentration was 0.010 ppm, with the statistical difference(P<0.05). The expression of RUNX2 and MDM21 was that normoxic control group > periodontitis group> chronic intermittent hypoxia group > compound group under the action with the concentration of 0.010 ppm for 12 h, but there was no significant difference for the comparison among groups(P>0.05). Conclusions: The condition of chronic intermittent hypoxia can reduce the expression of RUNX2 and MDM21 in rats with periodontitis and aggravate the damage of periodontal bone.

Atorvastatin Attenuates Myocardial Hypertrophy Induced by Chronic Intermittent Hypoxia In Vitro Partly through miR-31/PKCε Pathway

Atorvastatin is proven to ameliorate cardiac hypertrophy induced by chronic intermittent hypoxia （CIH）. However, little is known about the mechanism by which atorvastatin modulates CIH-induced cardiac hypertrophy, and whether specific hypertrophyrelated microRNAs are involved in the modulation. MiR-31 plays key roles in the development of cardiac hypertrophy induced by ischemia/hypoxia. This study examined whether miR-31 was involved in the protective role of atorvastatin against CIH-induced myocardial hypertrophy. H9c2 cells were subjected to 8-h intermittent hypoxia per day in the presence or absence of atorvastatin for 5 days. The size of cardiomyocytes, and the expression of caspase 3 and miR-31 were determined by Western blotting and RT-PCR, respectively. MiR-31 mimic or Ro 31-8220, a specific inhibitor of protein kinase C epsilon （PKCε）, was used to determine the role of miR-31 in the anti-hypertrophic effect of atorvastatin on cardiomyocytes. PKCε in the cardiomyocytes with miR-31 upregulation or downregulation was detected using RT-PCR and Western blotting. The results showed that CIH induced obvious enlargement of cardiomyocytes, which was paralleled with increased atrial natriuretic peptide （ANP）, brain natriuretic peptide （BNP）, and slow/beta cardiac myosin heavy-chain （MYHT） mRNA levels. All these changes were reversed by the treatment with atorvastatin. Meanwhile, miR-31 was increased by CIH in vitro. Of note, the atorvastatin pretreatment significantly increased the mRNA and protein expression of PKCε and decreased that of miR-31. Moreover, overexpression of miR-31 abolished the anti-hypertrophic effect of atorvastatin on cardiomyocytes. Upregulation and downregulation of miR-31 respectively decreased and increased the mRNA and protein expression of PKCε. These results suggest that atorvastatin provides the cardioprotective effects against CIH probably via up-regulating PKCε and down-regulating miR-31.

Evidence that chronic hypoxia causes reversible impairment on male fertility

Aim： To evaluate the effect of chronic hypoxia on human spermatogenic parameters and their recovery time. Methods： Seminological parameters of six male healthy mountain trekkers were evaluated in normoxia at sea level. After 26 days exposure to altitude （ranging from 2 000 m to 5 600 m, Karakorum Expedition） the same parameters were again evaluated after returning to sea level. These parameters were once again evaluated after 1 month and then again after 6 months. Results： Sperm count was found to be lower immediately after returning to sea level （P = 0.0004） and again after a month （P = 0.0008）. Normal levels were reached after 6 months. Spermatic motility （%） shows no reduction immediately after returning to sea level （P = 0.0583）, whereas after 1 month this reduction was significant （P = 0.0066）. After 6 months there was a recovery to pre-hypoxic exposure values. Abnormal or immature spermatozoa （%） increased immediately after returning to sea level （P = 0.0067） and then again after 1 month （P = 0.0004）. After 6 months there was a complete recovery to initial values. The total number of motile sperm in the ejaculate was found to be lower immediately after returning to sea level （P = 0.0024） and then again after 1 month （P = 0.0021）. After 6 months there was a recovery to pre-hypoxic exposure values. Conclusion： Chronic hypoxia induces a state of oligospermia and the normalization of such seminological parameters at the restoration of previous normoxic conditions after 6 months indicate the influence of oxygen supply in physiological mechanisms of spermatogenesis and male fertility.

Influence of chronic intermittent hypoxia on growth associated protein 43 expression in the hippocampus of young rats

This study aimed to explore the pathological change to hippocampal neurons and the expression of growth associated protein 43 in 21-day-old young rats following chronic intermittent hypoxia. Hematoxylin-eosin staining results showed varying degrees of degeneration and necrosis in hippocampal neurons depending on the modeling time. Immunohistochemistry revealed that growth associated protein 43 expression in young rats following chronic intermittent hypoxia decreased, but that levels were still higher than those of normal rats at each time point, especially 4 weeks after modeling. During 1 5 weeks after modeling, a slow growth in rat weight was observed. Experimental findings indicate that chronic intermittent hypoxia may induce growth dysfunction and necrosis of hippocampal neurons, as well as increase the expression of growth associated protein 43 in young rats.

Changes of hypoxia-inducible factor-1 signaling and the effect of cilostazol in chronic cerebral ischemia

Hypoxiainducible factor1 and its specific target gene heme oxygenase1, are involved in acute cerebral ischemia. However, very few studies have examined in detail the changes in the hy poxiainducible factor1/heme oxygenase1 signaling pathway in chronic cerebral ischemia. In this study, a rat model of chronic cerebral ischemia was established by permanent bilateral common carotid artery occlusion, and these rats were treated with intragastric cilostazol （30 mg/kg） for 9 weeks. Morris water maze results showed that cognitive impairment gradually worsened as the cerebral ischemia proceeded. Immunohistochemistry, semiquantitative PCR and western blot analysis showed that hypoxiainducible factorla and heme oxygenase1 expression levels in creased after chronic cerebral ischemia, with hypoxiainducible factorla expression peaking at 3 weeks and heme oxygenase1 expression peaking at 6 weeks. These results suggest that the elevated levels of hypoxiainducible factorla may upregulate heine oxygenase1 expression fol lowing chronic cerebral ischemia and that the hypoxiainducible factor1/heme oxygenase1 sig naling pathway is involved in the development of cognitive impairment induced by chronic cerebral ischemia. Cilostazol treatment alleviated the cognitive impairment in rats with chronic cerebral ischemia, decreased hypoxiainducible factorla and heme oxygenase1 expression levels, and reduced apoptosis in the frontal cortex. These findings demonstrate that cilostazol can protect against cognitive impairment induced by chronic cerebral ischemic injury through an antiapoptotic mechanism.

Establishment and Characterization of Chronic-hypoxia-resistant Gastric Cancer Cell Line MNK45/HYP

The chronic-hypoxia-resistant gastric cancer cell line was established,and its biological characteristics were explored and compared with the parental cell line.Gastric cancer cell lines were cultured under the degressive oxygen concentration.Cell doubling time was calculated by cell counting method.Chemo-resistance ability of cells was tested by MTT assay.Irradiation tolerance of cells was evaluated by colony forming method.Cell cycle distribution was tested with flow cytometry.Invasive ability was tested by Transwell method.The expression levels of GLUT-1 and HIF-1α were detected by using Western blot.MNK45/HYP cells successfully survived under the 1% concentration of oxygen and its cell doubling time was 35.01±1.02 h,while that of MNK45 was 27.35±0.83 h（P〈0.01）.The percentage of MNK45/HYP cells in G0/G1 stage was（58.3±6.1）%,and that of MNK45 cells was（42.2±6.0）%（P〈0.05）.Comparing with the parental cells MNK45,drug resistance indexes of 5-Fu,PTX,OXA,Sn38,GEM and VP16 in MNK45/HYP cells were respectively 5.3,1.3,3.6,2.2,4.8 and 4.4.Colony forming ability of MNK45/HYP cells after irradiation was also significantly higher than MNK45 cells.The invasive number of MNK45/HYP cells was 107.7±17.5,while that of MNK45 cells was 59.0±9.9.The expression levels of GLUT-1 and HIF-1α in MNK45/HYP cells were significantly higher than those in MNK45 cells.MNK45/HYP cells hold biological characteristics of hypoxia tumor with good tolerance to chronic hypoxia,and can be used for the research of solid tumor under chronic hypoxia condition.

The Effects of Chronic Hypoxia on Thermoregulation and Metabolism in Phrynocephalus vlangalii

Phrynocephalus vlangalii are widely distributed on Tibetan plateau spanning diverse altitudes and habitats. In the present study, P vlangalii were exposed to 8% oxygen concentration in a hypoxic chamber for 6 weeks. Then the body temperature （Tb）, standard metabolic rate （SMR）, heart rate and metabolic enzyme activities of the lizards were measured at 20℃ and 30℃. The results indicated that hypoxia exposure decreased Tb, SMR and heart rate. Lactate dehydrogenase （LDH） activity of 8% 02 group became significant elevated in liver and skeletal muscle compared with control group at 20℃, but descended significantly in heart. Using electrophoresis we found that LDH contains five isozymes （LDH1, LDH2, LDH3, LDH4 and LDH5） and are expressed specifically in liver, skeletal muscle and heart. Citrate synthase （CS） activity in the liver also decreased at 20℃ and 30℃. No significant difference of CS activity was found between the two groups in skeletal muscle and heart.

Adiponectin Ameliorated Pancreatic Islet Injury Induced by Chronic Intermittent Hypoxia through Inhibiting the Imbalance in Mitochondrial Fusion and Division

Objective This study aimed to assess the protective value of adiponectin(APN)in pancreatic islet injury induced by chronic intermittent hypoxia(CIH).Methods Sixty rats were randomly divided into three groups:normal control(NC)group,CIH group,and CIH with APN supplement(CIH+APN)group.After 5 weeks of CIH exposure,we conducted oral glucose tolerance tests(OGTT)and insulin released test(IRT),examined and compared the adenosine triphosphate(ATP)levels,mitochondrial membrane potential(MMP)levels,reactive oxygen species(ROS)levels,enzymes gene expression levels of Ant1,Cs,Hmox1,and Cox4 i1 which represented mitochondrial tricarboxylic acid cycle function,the protein and gene expression levels of DRP1,FIS1,MFN1,and OPA1 which represented mitochondrial fusion and division,and the protein expression levels of BAX,BCL-2,cleaved Caspase-3,and cleaved PARP which represented mitochondrial associated apoptosis pathway of pancreatic islet.Results OGTT and IRT showed blood glucose and insulin levels had no differences among the NC,CIH and CIH+APN groups(both P>0.05)at 0 min,20 min,30 min,60 min,120 min.However,we found that compared to NC group,CIH increased the ROS level,reduced ATP level and MMP level.The islets of CIH exposed rats showed reduced gene expression levels of Ant1,Cs,Hmox1,and Cox4 i1,decreased protein and gene expression levels of MFN1 and OPA1,increased protein and gene expression levels of DRP1 and FIS1,increased protein expression levels of cleaved Caspase-3 and cleaved PARP,with lower ratio of BCL-2/BAX at protein expression level.All the differences among three groups were statistically significant.APN treated CIH rats showed mitigated changes in the above measurements associated with islet injuries.Conclusion APN may ameliorate the pancreatic islet injury induced by CIH via inhibiting the imbalance in mitochondrial fusion and division.

Effects of Endoplasmic Reticulum Stress on Pulmonary Hypertension in Rat Induced by Chronic Hypoxia and Hypercapnia

Objective: To observe the pulmonary vascular remodeling in rats with pulmonary hypertension induced by hypoxia and hypercapnia, and to explore the role of endoplasmic reticulum stress in pulmonary hypertension. Methods: 1) 40 SD rats were randomly divided into four groups: normoxic control group (N), hypoxia hypercapnia group (HH), endoplasmic reticulum stress (ERS) inhibitor 4-phenyl butyric acid group (4-PBA), ERS pathway agonist tunicamycin group (TM). 2) The mean pulmonary arterial pressure (mPAP) and the right ventricular hypertrophy index (RV/(LV + S)) were measured in each group. 3) Identification of pulmonary artery smooth muscle cells (PASMCs) in each group by immunofluorescence α-SMA. 4) Morphological changes of lung tissue and pulmonary artery were observed by electron microscope. 5) The apoptotic index of PASMCs in each group was detected by TUNEL. 6) Reverse transcription polymerase chain reaction (RT-PCR) and Western Blot (WB) were used to detect the expression of ERS related protein and mRNA (GRP78, CHOP, JNK, Caspase-12) in each group. Results: 1) Compared with the N group, the mPAP, RV/(LV + S) and vascular wall area (WA)/total area (TA) value of HH group, 4-PBA group and TM group were increased (P < 0.01), and the vascular lumen area (LA)/TA values, PASMCs apoptosis index were significantly decreased. GRP78, CHOP, JNK, Caspase-12 expression were increased, and the differences were statistically significant. 2) Compared with the HH group, the mPAP, RV/(LV + S) and WA/TA of 4-PBA group were decreased (P < 0.01);the LA/TA value and PASMCs apoptosis index were increased (P < 0.05);and the mRNA and protein expression of CHOP, JNK, Caspase-12 and GRP78 had a significant decrease (P < 0.05). 3) Compared with the HH, the mPAP, RV/(LV + S) and WA/TA of TM group were increased (P P P < 0.01);and? PASMCs apoptotic index was increased (P < 0.01). Meanwhile, the mRNA expression of Caspase-12, CHOP, JNK and GRP78 was increased to varying degrees (P < 0.05), and the protein expression of Caspase-12, CHOP and JNK was also increased significantly (P Conclusion: Hypoxia and hypercapnia induced pulmonary vascular remodeling may be related to the proliferation of PASMCs, and ERS related factors (JNK, Caspase12 and CHOP) are involved in the regulation of hypoxic hypercapnia.

DL-3-n-butylphthalide improved physical and learning and memory performance of rodents exposed to acute and chronic hypobaric hypoxia

Background:Studies have revealed the protective effect of DL-3-n-butylphthalide(NBP)against diseases associated with ischemic hypoxia.However,the role of NBP in animals with hypobaric hypoxia has not been elucidated.This study investigated the effects of NBP on rodents with acute and chronic hypobaric hypoxia.Methods:Sprague-Dwaley rats and Kunming mice administered with NBP(0,60,120,and 240 mg/kg for rats and 0,90,180,and 360 mg/kg for mice)were placed in a hypobaric hypoxia chamber at 10,000 m and the survival percentages at 30 min were determined.Then,the time and distance to exhaustion of drug-treated rodents were evaluated during treadmill running and motor-driven wheel-track treadmill experiments,conducted at 5800 m for 3 days or 20 days,to evaluate changes in physical functions.The frequency of active escapes and duration of active escapes were also determined for rats in a shuttle-box experiment,conducted at 5800 m for 6 days or 27 days,to evaluate changes in learning and memory function.ATP levels were measured in the gastrocnemius muscle and malonaldehyde(MDA),superoxide dismutase(SOD),hydrogen peroxide(H_(2)O_(2)),glutathione peroxidase(GSH-Px),and lactate were detected in sera of rats,and routine blood tests were also performed.Results:Survival analysis at 10,000 m indicated NBP could improve hypoxia tolerance ability.The time and distance to exhaustion for mice(NBP,90 mg/kg)and time to exhaustion for rats(NBP,120 and 240 mg/kg)significantly increased under conditions of acute hypoxia compared with control group.NBP treatment also significantly increased the time to exhaustion for rats when exposed to chronic hypoxia.Moreover,240 mg/kg NBP significantly increased the frequency of active escapes under conditions of acute hypoxia.Furthermore,the levels of MDA and H_(2)O_(2) decreased but those of SOD and GSH-Px in the sera of rats increased under conditions of acute and chronic hypoxia.Additionally,ATP levels in the gastrocnemius muscle significantly increased,while lactate levels in sera significantly decreased.Conclusion:NBP improved physical and learning and memory functions in rodents exposed to acute or chronic hypobaric hypoxia by increasing their anti-oxidative capacity and energy supply.

Transcriptional Profile Alteration of Peripheral Blood in Chronic Hypoxia

Objective Many physiological and pathological conditions,including cyanotic congenital heart diseases(CCHD),are accompanied by chronic hypoxia,which might interfere with the transcription process.However,the transcriptome profile in peripheral blood under hypoxia is still unidentified.The present work aimed to explore the transcriptional profile alteration of peripheral blood in chronic hypoxia.Methods The present study used a chronic hypoxia rat model to simulate the hypoxic state of CCHD patients.Two groups of Sprague-Dawley rats(n=6 per group)were either exposed to hypoxia(10%O2)or normoxia(21%O2)for 3 weeks.Body weight was measured weekly.Peripheral blood was collected and total RNA was extracted for RNA-Seq at the end of the hypoxia treatment.After quality assessment,the library was sequenced by the Illumina Hiseq platform.The differentially expressed genes were screened(false discovery rate<0.05 and fold change>2).The functional annotation analysis and cluster analysis of differentially expressed genes were performed based on the adjusted P-value(padj<0.05).Results Compared with the control group,the body weight of the rats in the hypoxia group was significantly lowered(P<0.01).RNA-Seq results showed that the transcriptome patterns of the two groups had significant differences.In total,872 genes were identified as differentially expressed.Among all,803 genes were downregulated,while only 69 genes were up-regulated in the hypoxia group.The functional enrichment analysis of the 872 genes showed that multiple biological processes involved,such as porphyrin-containing compound metabolic process,hemoglobin complex and oxygen transporter activity.Conclusions Our study demonstrated the transcriptional profile alteration in peripheral blood of chronic hypoxia rat model.This study provided basic data and directions to further understand the physiological and pathological changes in patients with CCHD.

Study of band 3 protein and intraerythrocytic acid-base regulation under chronic isobaric hypoxia and hypoxia-hypercapnia in rats

The changes of the structure and content of the erythrocyte membrane band 3 protein and its function of anion transport and blood gases inside and out of the erythrocytes were observed under isobaric hypoxia and hypoxia-hypercapnia in rats. It was found t

PGE₂Generation in Myocardium from Isolated Rat Atrium under Hypoxia and Reoxygenation Conditions. Effect of Anti-<i>β</i>₁IgG from Patients with Chronic Severe Periodontitis

Background: Hypoxia is one of the most frequently encountered stresses in health and disease. Methods: We compared the effects of an anti-β1 periodontal IgG (pIgG) and an authentic β1 adrenergic agonist, xamoterol, on isolated myocardium from rat atria contractility. We used an ELISA assay to measure the generation of PGE2 in vitro after the addition of either the antibody or the adrenergic agonist. We analyzed the myocardium histopathologically in the presence of both the antibody and/or the adrenergic agonist drug during normoxia, hypoxia and reperfusion conditions. Results: PGE2 generation increased during the hypoxia and was unchanged during reoxygenation period compared with the production of this prostanoid in atria during normoxia condition. A β1 specific adrenoceptor antagonist atenolol and the β1 synthetic peptide abrogated the increment of the prostanoid in the presence of pIgG but only atenolol due to it in the presence of xamoterol. The increment of PGE2 was dependent on the activation of cox-1 and cox-2 isoforms. Moreover, cox-2 was more active and produced more increments in the production of PGE2 in the presence of the pIgG than cox-1 activation. Histopathologically, studies of myocardium specimens during these different periods of the experimental protocol: basal (B), hypoxia (H) and reoxygenation (R), were also performed and showed tissue necrosis and edematization at the myocardium level. Conclusion: The phenomenon studied here supports the notion that PGE2 may be responsible for tissue edematization. PGE2 maybe acts as a beneficial modulator in the myocardium and prevents a major injury of it. The inflammation damage to the heart organ and cardiomyocytes caused by the actions of the antibodies in the course of heart lesions provoked by cardiovascular autoimmune disease, explains some of these results obtained in the present experiments. Further studies will be needed to establish the real role of PGE2 during hypoxia injury of the heart in the course of autoimmune diseases.