Antioxidant responses to chronic hypoxia in the rat cerebellum and pons

Obstructive sleep apnea (OSA) is characterized by chronic intermittent hypoxia (CIH) and sleep fragmentation and deprivation. Exposure to CIH results in oxidative stress in the cortex, hippocampus and basal forebrain of rats and mice. We show that sustained and intermittent hypoxia induces antioxidant responses, an indicator of oxidative stress, in the rat cerebellum and pons. Increased glutathione reductase (GR) activity and thiobarbituric acid reactive substance (TBARS) levels were observed in the pons and cerebellum of rats exposed to CIH or chronic sustained hypoxia (CSH) compared with room air (RA) controls. Exposure to CIH or CSH increased GR activity in the pons, while exposure to CSH increased the level of TBARS in the cerebellum. The level of TBARS was increased to a greater extent after exposure to CSH than to CIH in the cerebellum and pons. Increased superoxide dismutase activity (SOD) and decreased total glutathione (GSHt) levels were observed after exposure to CIH compared with CSH only in the pons. We have previously shown that prolonged sleep deprivation decreased SOD activity in the rat hippocampus and brainstem, without affecting the cerebellum, cortex or hypothalamus. We therefore conclude that sleep deprivation and hypoxia differentially affect antioxidant responses in different brain regions.     

Protective effects of long term dietary restriction on swimming exercise-induced oxidative stress in the liver, heart and kidney of rat

In this study, we evaluated the hypothesis that long term dietary restriction would have beneficial effects on the oxidative stress and antioxidant enzyme systems in liver, heart and kidney in adult male rats undergoing different intensities of swimming exercise. Sixty male, Sprague-Dawley rats were assigned as either dietary restricted on every other week day (DR) or fed ad libitum (AL) groups, and each group was further subdivided into sedentary, endurance swimming exercise training (submaximal exercise) and exhaustive swimming exercise (maximal exercise) groups. Animals in the submaximal exercise group swam 5 days/week for 8 weeks, while maximal exercise was performed as an acute bout of exercise. In parallel with the increase in the intensity of the exercise, the degree of lipid peroxidation and protein oxidation were increased in both the DR and AL groups; however the rate of increase was lower in the DR group. Reduced glutathione (GSH), glutathione peroxidase (GSH-Px) and glutathione reductase (GR) enzyme activities were lower in the DR group than in the AL group. In parallel with the increase in exercise intensity, GSH and GR enzyme activities decreased, whereas an increase was observed in GSH-Px enzyme activity. In conclusion, the comparison between the DR and AL groups with the three swimming exercise conditions shows that the DR group is greatly protected against different swimming exercise-induced oxidative stress compared with the AL group.     

Effects of hypobaric hypoxia on the oxidative capacity of the extensor digitorum longus motor units in the rat

The fiber number, fiber type distribution, and succinate dehydrogenase activity were investigated from the fast-twitch extensor digitorum longus muscle of male rats exposed to 7 weeks of hypobaric hypoxia. The oxidative metabolic capacity of the motoneurons in the extensor digitorum longus neuron pool was also determined from quantitative histochemical analyses. The fiber number and oxidative enzyme activity of the muscle were not changed by hypoxia. An increase in the percentage of fast-twitch oxidative (FO) fibers and a concemitant decrease in the percentage of fast-twitch (F) fibers were observed in the hypoxic muscle. On the other hand, the oxidative capacity of small-to medium-sized alpha motoneurons (25–45 m average soma diameter) was increased. The increase in the oxidative capacity of small- to medium-sized motoneurons and the type shift of muscle fibers from F (low-oxidative) to FO (high-oxidative) indicate that hypoxia enhances the oxidative capacity of particular motor units in the neuron pool.     

间歇性低压低氧与连续性低压低氧对大鼠血液动力学作用的比较(英文)

本研究旨在探讨并比较慢性间歇性低压低氧（intermitten thypobaric hypoxia,IHH）和慢性连续性低压低氧（continuous hypobaric hypoxia,CHH）对大鼠血液动力学作用的影响。40只成年Sprague—Dawley大鼠随机分为5组：对照组（CON）,28天IHH处理组（IHH28）,42天IHH处理组（IHH42）,28天CHH组（CHH28）和42天CHH组（CHH42）。IHH火鼠于低压氧舱分别接受28或42天模拟5000m海拔高度低氧（11．1％O2）处理、每天6h。CHH处理大鼠生活在低压氧舱环境中,除每天半小时常氧供食、供水和清洁外,其余时间均分别接受时程为28或42天的模拟5000m海拔高度低氧（11．1％O2）处理。每周定时测定大鼠体重。通过导管法测定基础常氧和急性低氧状态下的血液动力学,包括半均动脉压（meanartery blood pressure,MAP）、心率（heartrate,HR）、左审收缩峰压（1eft ventricular systolic pressure,LVSP）、正负左率最人压力变化速率（maximum change rate of left ventricular pressure,±LVdP／dtmax）。通过生物化学方法测定大鼠心肌超氧化物岐化酶活性和丙二醛含量。并分别测定全心、左心室和右心室重量。结果显示：（1）CHH42大鼠基础HR和MAP低于CON,IHH和CHH28大鼠（P〈0．05）。（2）IHH大鼠表现出明显的抗心肌缺氧／复氧损伤作用,表现为急性低氧状态下的HR、MAP、LVSP和＋LVdP/dtmax,改变明显低于CON大鼠（P〈0．05）;CHH大鼠表现出更为明显的抗急性低氧心脏保护作用,表现为急性低氧的HR、MAP、LVSP和±LVdP/dtmax;改变明显低于CON和IHH火鼠（P〈0．05）,但出现复氧损伤作用,表现为复氧过程中血液动力学的恢复明显低于CON和IHH大鼠（P〈0．05）。（3）与CON大鼠相比较,IHH和CHH大鼠心肌抗氧化能力明显增强（P〈0．05,P〈0．01）。（4）与IHH和CON大鼠相比较,CHH大鼠表现明显的右心室肥厚（P〈0．01）。结果表明,IHH可诱导有效的心脏保护作用,而无明显的不良反应,因而具有潜在的实际应用价值。     

氢气对慢性间歇性低氧大鼠肝脏氧化应激损伤的改善作用

目的：研究氢气对慢性间歇性低氧大鼠肝脏损伤的改善作用。方法：24只雄性成年SD大鼠,随机分为3组（n=8）：常氧组（Norm）、慢性间歇性低氧组（CIH）、氢气+慢性间歇性低氧组（H₂+CIH）。Norm组暴露于空气中,CIH组与H₂+CIH组接受间歇性低氧处理5周,其中H₂+CIH组在间歇性低氧处理前给予1 h 67%浓度的氢气吸入。5周后比较各组大鼠血清氧化应激指标、炎症因子指标、肝酶水平、血脂水平,并在电镜下观察大鼠肝组织超微结构变化。结果：与Norm组相比,CIH组肝组织超微结构受损严重,谷丙转氨酶（ALT）、谷草转氨酶（AST）水平显著升高（P<0.05）;血清8-羟基脱氧鸟苷（8-OHdG）水平显著升高;超氧化物歧化酶（SOD）活性显著降低;白介素-6（IL-6）水平显著升高。与CIH组相比,H₂+CIH组肝组织超微结构损伤减轻,ALT、AST水平显著降低（P<0.05）;8-OHdG与IL-6水平显著降低,SOD活性显著升高。与Norm组相比,CIH组IL-1水平升高;血清TC、TG、LDL水平升高,但无统计学差异。HDL在各组之间无统计学差异。结论：氢气可以减轻慢性间歇性低氧对大鼠肝脏的损伤,有效降低氧化应激水平,保护肝细胞受损。     

红花注射液对慢性低O2高CO2肺动脉高压的影响

目的：探讨红花注射液对大鼠在慢性低O2高CO2下肺动脉高压的抑制作用。方法：将SD大鼠分为对照组,慢性低O2高CO2组,慢性低O2高CO2＋红花注射液组。用电镜、放免等方法,观察各组大鼠肺动脉平均压、颈动脉平均压、肺细小动脉显微结构、血浆和肺匀浆TXB2及6-keto-PGF1a含量的变化。结果：①慢性低O2高CO2组mPAP比对照组显著增高,红花注射液组的mPAP比慢性低O2高CO2组显著降低,3组间mCAP比较差异无显著性。②慢性低O2高CO2组与对照组相比血浆和肺匀浆TXB2浓度、TXB2／6-keto-PGF1a比值显著增高,6-keto-PGF1a浓度显著下降;红花注射液组与慢性低P2高CO2相比血浆和肺匀浆TXB2浓度、TXB2／6-keto-PGF1a显著下降,6-keto-PGF1a显著升高。③光镜下慢性低O2高CO2组与对照组相比,肺细小动脉管壁面积／管总面积（WA／TA）和肺细小动脉中膜厚度（PAMT）均显著增高。红花注射液组WA／TA和PAMT显著降低。④电镜下慢性低O2高CO2组大鼠肺细小动脉内皮细胞吞饮小泡增多,血管壁增厚,中膜平滑肌细胞增生,纤维细胞增多,肺泡Ⅱ型上皮细胞微绒毛脱落;红花注射液组肺细小动脉中膜平滑肌细胞增生减轻,纤维细胞少,胶原纤维减少,肺泡Ⅱ型上皮细胞微绒毛丰富、结构清。结论：红花注射液有减轻慢性低O2高CO2性肺动脉高压和肺血管结构重建的作用,可能与抑制TXA2的合成,保护血管内皮细胞,使TXA2/PGI2比值降低有关.     

Effect of dietary ascorbic acid supplementation and chronic hypoxia on sea bream growth and vitamin C status

Hypoxia (55% DO) and ascorbic acid (AA) supplementation level (0, 10, 25 and 50 mg AA equivalent kg^—1 diet, supplied as ascorbyl polyphosphate) did not significantly alter juvenile sea bream Sparus aurata growth, body composition, survival and skin hydroxyproline concentration. Liver, head kidney and spleen AA concentrations significantly decreased with decreasing dietary AA level, but were not influenced by hypoxia. This study showed that sea bream AA requirements were not influenced by chronic hypoxic stress.     

慢性低氧对大鼠肺内几种原癌基因表达的影响

本文用原位杂交技术动态观察了慢性低氧大鼠肺内原癌基因ｊｕｎ、ｆｏｓ和ｍｙｂ的表达,结果发现：（１）正常大鼠肺内有一定量的ｊｕｎｍＲＮＡ表达,少见到ｍｙｂ及ｆｏｓ的表达;（２）低氧１周时,ｊｕｎ的表达较正常下降,２周后有所增加。低氧３周后,ｊｕｎ的ｍＲＮＡ表达较正常明显上升;（３）低氧１、２周后,ｍｙｂ的表达明显增加,３周时基本恢复到正常水平;（４）ｆｏｓ原癌基因在低氧１、２周时有一定量的表达,低氧３周时达最大值。提示低氧可刺激大鼠肺内原癌基因ｊｕｎ、ｍｙｂ和ｆｏｓ的表达。     

Potential role for pyruvate kinase M2 in the regulation of murine cardiac glycolytic flux during in vivo chronic hypoxia

Carbohydrate metabolism in heart failure shares similarities to that following hypoxic exposure, and is thought to maintain energy homoeostasis in the face of reduced O₂ availability. As part of these in vivo adaptations during sustained hypoxia, the heart up-regulates and maintains a high glycolytic flux, but the underlying mechanism is still elusive. We followed the cardiac glycolytic responses to a chronic hypoxic (CH) intervention using [5-³H]-glucose labelling in combination with detailed and extensive enzymatic and metabolomic approaches to provide evidence of the underlying mechanism that allows heart survivability. Following 3 weeks of in vivo hypoxia (11% oxygen), murine hearts were isolated and perfused in a retrograde mode with function measured via an intraventricular balloon and glycolytic flux quantified using [5-³H]-glucose labelling. At the end of perfusion, hearts were flash-frozen and central carbon intermediates determined via liquid chromatography tandem mass spectrometry (LC-MS/MS). The maximal activity of glycolytic enzymes considered rate-limiting was assessed enzymatically, and protein abundance was determined using Western blotting. Relative to normoxic hearts, CH increased ex vivo cardiac glycolytic flux 1.7-fold with no effect on cardiac function. CH up-regulated cardiac pyruvate kinase (PK) flux 3.1-fold and cardiac pyruvate kinase muscle isoenzyme M2 (PKM2) protein content 1.4-fold compared with normoxic hearts. CH also augmented cardiac pentose phosphate pathway (PPP) flux, reflected by higher ribose-5-phosphate (R5P) content. These findings support an increase in the covalent (protein expression) and allosteric (flux) control of PKM2 as being central to the sustained up-regulation of the glycolytic flux in the chronically hypoxic heart.     

Sensory plasticity of carotid body is correlated with oxidative stress in paraventricular nucleus during chronic intermittent hypoxia

Chronic intermittent hypoxia (CIH) is known to induce hypertension, but the mechanism is not well understood. We hypothesized that sensory plasticity of the carotid body (CB) and oxidative stress in the paraventricular nucleus (PVN) are involved in CIH-induced hypertension. In this study, rats were exposed to CIH for 28 days (intermittent hypoxia of 21% O₂ for 60 s and 5% O₂ for 30 s, cyclically repeated for 8 hr/day) and then randomly grouped for intracerebroventricular injection of 5-HT2 receptor antagonist ritanserin, Rho-associated protein kinase (ROCK) inhibitor Y-27632, and NADPH oxidase (NOX) inhibitor diphenyleneiodonium (DPI), respectively. We found that CIH increased blood pressure (BP), elevated carotid sinus nerve (CSN) and renal sympathetic nerve (RSN) activities, oxidative stress, and cell apoptosis in PVN. NOX-derived reactive oxygen species (ROS) production and cell apoptosis decreased when CIH-induced activation of 5-HT/5-HT2AR/PKC signaling was inhibited by ritanserin. In addition, RhoA expression was downregulated when oxidative stress was attenuated by DPI, while Y-27632 decreased the expression of endothelin-1, which is overexpressed in the vascular wall during hypertension. Moreover, treatment with ritanserin, DPI or Y-27632 attenuated the sensory plasticity and sympathetic hyperactivity as well as CIH-induced elevation of BP. In conclusion, CIH-induced activation of 5-HT/5-HT2AR/PKC signaling contributes to NOX-derived oxidative stress in PVN, which may cause sensory plasticity of CB, RSN hyperactivity, and elevated BP.     

Differential metabolic adaptation to acute and long-term hypoxia in rat primary cortical astrocytes

Brain astrocytes provide structural and metabolic support to surrounding cells during ischemia. Glucose and oxygen are critical to brain function, and glucose uptake and metabolism by astrocytes are essential to their metabolic coupling to neurons. To examine astrocyte metabolic response to hypoxia, cell survival and metabolic parameters were assessed in rat primary cortical astrocytes cultured for 3 weeks in either normoxia or in either 1 day or 3 weeks sustained hypoxia (5% O2). Although cell survival and proliferation were not affected by the mildly hypoxic environment, substantial differences in glucose consumption and lactate release after either acute or prolonged hypoxia suggest that astrocyte metabolism may contribute to their adaptation. Hypoxia over a period of 1 day increased glucose uptake, lactate release, and glucose transporter 1 (GLUT1) and monocarboxylate transporter 1 (MCT1) expression, whereas hypoxia over a period of 3 weeks resulted in a decrease of all parameters. Furthermore, increased glucose uptake at 1 day of hypoxia was not inhibited by cytochalasin B suggesting the involvement of additional glucose transporters. We uncovered hypoxia-regulated expression of sodium-dependent glucose transporters (SGLT1) in astrocytes indicating a novel adaptive strategy involving both SGLT1 and GLUT1 to regulate glucose intake in response to hypoxia. Overall, these findings suggest that although increased metabolic response is required for the onset of astrocyte adaptation to hypoxia, prolonged hypoxia requires a shift to an energy conservation mode. These findings may contribute to the understanding of the relative tolerance of astrocytes to hypoxia compared with neurons and provide novel therapeutic strategies aimed at maintaining brain function in cerebral pathologies involving hypoxia.     

间歇性低压低氧通过促进细胞凋亡抗大鼠胶原诱导性关节炎

本文旨在研究慢性间歇性低压低氧(chronic intermittent hypobaric hypoxia,CIHH)对大鼠胶原诱导性关节炎(collagen-induced arthritis,CIA)影响.雄性成年Sprague-Dawley大鼠50只,随机分为5组:CIHH预处理组(Pre-T)、预处理对照组(...     

Differential responses of carbon‐degrading enzyme activities to warming: Implications for soil respiration

Extracellular enzymes catalyze rate‐limiting steps in soil organic matter decomposition, and their activities (EEAs) play a key role in determining soil respiration (SR). Both EEAs and SR are highly sensitive to temperature, but their responses to climate warming remain poorly understood. Here, we present a meta‐analysis on the response of soil cellulase and ligninase activities and SR to warming, synthesizing data from 56 studies. We found that warming significantly enhanced ligninase activity by 21.4% but had no effect on cellulase activity. Increases in ligninase activity were positively correlated with changes in SR, while no such relationship was found for cellulase. The warming response of ligninase activity was more closely related to the responses of SR than a wide range of environmental and experimental methodological factors. Furthermore, warming effects on ligninase activity increased with experiment duration. These results suggest that soil microorganisms sustain long‐term increases in SR with warming by gradually increasing the degradation of the recalcitrant carbon pool.     

CLA对急性缺氧大鼠肝脏线粒体呼吸链酶活性及氧化应激的影响

目的:观察共轭亚油酸(CLA)对急性缺氧大鼠肝脏线粒体呼吸链酶活性及肝脏内氧化应激(OS)的影响。方法:将60只SD大鼠随机分为正常对照组,模拟海拔5000米高原环境连续缺氧暴露3d的急性缺氧组,急性缺氧CLA干预组。生化法测定肝脏组织中丙二醛(MDA)、还原型谷胱甘肽(GSH)含量及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性,Clark氧电极法观察大鼠肝脏线粒体呼吸链酶活性。结果:成功诱导大鼠急性缺氧模型。与对照组比,急性缺氧组大鼠肝脏MDA含量明显升高(P<0.05),同时肝脏线粒体呼吸链酶活性以及抗氧化酶活性(SOD,CAT)及GSH显著降低(P<0.05),与急性缺氧相比,CLA治疗组大鼠以上各项指标均有改善,并存在一定的剂量效应关系。结论:CLA通过抑制氧化应激增强大鼠肝脏线粒体呼吸链酶活性改善了急性缺氧大鼠肝脏的能量代谢障碍,对急性缺氧引起的氧化损伤有保护作用。     

Molecular cloning and restriction enzyme analysis of a long repetitive DNA sequence in rice

Rice long repetitive DNA (9–20 kbp) reassociating at Cot 50 M.s was cloned in pBR325. Out of several recombinants (Cam^r Amp^r Tet^s), only a few were selected randomly for further characterization. The insert size in all these clones was 3–4 kbp. Restriction enzyme analysis showed the absence ofEcoRI andBclI sites, presence of a singlePstI andPvuII site and multiple sites forAluI in 3 clones namely pRLl, pRL7 and pRL10. TheBamHI-PstI fragment of about 0.4 kbp in the pRL7 insert DNA (pRL7-0.4 kbp) was subcloned in M13mpl8 and partially sequenced using Sanger’s dideoxynucleotide chain termination method. Dot matrix comparison of this sequence with rice rDNA sequences revealed low homology with the 25 S rDNA sequence of rice, however, hybridisation did not indicate any homology.     

An approach to the hypoxic and oxidative stress responses in Kluyveromyces lactis by analysis of mRNA levels

Genome duplication, after the divergence of Saccharomyces cerevisiae from Kluyveromyces lactis along evolution, has been proposed as a mechanism of yeast evolution from strict aerobics, such as Candida albicans, to facultatives/fermentatives, such as S. cerevisiae. This feature, together with the preponderance of respiration and the use of the pentose phosphate pathway in glucose utilization, makes K. lactis a model yeast for studies related to carbon and oxygen metabolism. In this work, and based on the knowledge of the sequence of the genome of K. lactis, obtained by the Génolevures project, we have constructed DNA arrays from K. lactis including a limited amount of selected probes. They are related to the aerobiosis-hypoxia adaptation and to the oxidative stress response, and have been used to test changes in mRNA levels in response to hypoxia and oxidative stress generated by H(2)O(2). The study was carried out in both wild-type and rag2 mutant K. lactis strains in which glycolysis is blocked at the phosphoglucose isomerase step. This approach is the first analysis carried out in K. lactis for the majority of the genes selected.     

A simple modification to improve the accuracy of methylation-sensitive restriction enzyme quantitative polymerase chain reaction

DNA digestion with endonucleases sensitive to CpG methylation such as HpaII followed by polymerase chain reaction (PCR) quantitation is commonly used in molecular studies as a simple and inexpensive solution for assessment of region-specific DNA methylation. We observed that the results of such analyses were highly overestimated if mock-digested samples were applied as the reference. We determined DNA methylation levels in several promoter regions in two setups implementing different references: mock-digested and treated with a restriction enzyme that has no recognition sites within examined amplicons. Fragmentation of reference templates allowed removing the overestimation effect, thereby improving measurement accuracy.     

Combined influence of dietary restriction and treadmill running on MCP-1 and the expression of oxidative stress-related mRNA in the adipose tissue in obese mice

[Purpose]

This study suggests that the negative effects of inflammation caused by obesity could be prevented through diet restriction and exercise.

[Methods]

In this study, 44 C57/BL6 male mice at about 4 weeks old (Orient bio, South Korea) were given a high fat diet for 5 weeks to make them obese. To help the mice lose weight, their dietary intake was limited and they were exercised on the treadmill for 8 weeks, and during that period, we analyzed the changes of MCP-1, ERK, Mn-SOD, HIF-1, and NOX in epididymal adipose tissue. There ND control group and obese group with high fat diet (HFD), and it is divided into four groups; HFD-ND-EX group, HFD-ND-nonEX group, HFD-DR-EX group and HFD-DR-nonEX group.

[Results]

During their progress, the mRNA expressions of HIF-1α and ERK2 decreased, as did the expression of MCP-1 contained in the nucleus by suppressing oxygen free radicals, which was observed after the exercise program. However, dietary restriction without exercise training triggered an increase in the mRNA expression of MCP-1.

[Conclusion]

To put this in perspective, combining exercise and dietary intake restriction likely prevented an influx of macrophages by reducing the number of fat cells, whereas only dietary restriction was not effective against reducing inflammation.     

慢性低氧对雄性大鼠血浆皮质酮及睾酮水平的影响

目的:研究低氧对雄性大鼠性腺及相关激素水平的影响。方法:分别检测3km、5km及杭州海拔水平雄性大鼠睾丸和附睾指数、血浆皮质酮和睾酮水平。结果:3km组体重、睾酮含量均显著下降,睾丸指数、血浆皮质酮显著上升;5km组体重、附睾指数和睾酮含量均显著下降,皮质酮含量显著上升。结论:慢性低氧能显著影响雄性成年大鼠性腺及血浆睾酮水平,该结果显示哺乳动物在慢性低氧条件下生殖内分泌功能呈现抑制状态。     

Impact of chronic intermittent hypoxia on the long non-coding RNA and mRNA expression profiles in myocardial infarction

Chronic intermittent hypoxia (CIH) is the primary feature of obstructive sleep apnoea (OSA), a crucial risk factor for cardiovascular diseases. Long non-coding RNAs (lncRNAs) in myocardial infarction (MI) pathogenesis have drawn considerable attention. However, whether CIH participates in the modulation of lncRNA profiles during MI is yet unclear. To investigate the influence of CIH on MI, cardiac damage was assessed by histology and echocardiography, and lncRNA and mRNA integrated microarrays were screened. MI mouse model showed myocardial hypertrophy, aggravated inflammation and fibrosis, and compromised left ventricle function under CIH. Compared with normoxia, 644 lncRNAs and 1084 differentially expressed mRNAs were identified following CIH for 4 weeks, whereas 1482 lncRNAs and 990 mRNAs were altered at 8 weeks. Strikingly, reoxygenation after CIH markedly affected 1759 lncRNAs and 778 mRNAs. Of these, 11 lncRNAs modulated by CIH were restored after reoxygenation and were validated by qPCR. The GO terms and KEGG pathways of genes varied significantly by CIH. lncRNA-mRNA correlation further showed that lncRNAs, NONMMUT032513 and NONMMUT074571 were positively correlated with ZEB1 and negatively correlated with Cmbl. The current results demonstrated a causal correlation between CIH and lncRNA alternations during MI, suggesting that lncRNAs might be responsible for MI aggravation under CIH.