Characterization of group Ⅰ metabotropic glutamate receptors in rat superior cervical ganglion and their changes following chronic intermittent hypoxia / 解剖学报

Objective To observe the expression and localization of group Ⅰ metabotropic glutamate receptors (mGluR1/ 5) in rat superior cervical ganglion (SCG) and the effect of chronic intermittent hypoxia (CIH) on mGluR1/ 5 protein level. Methods Twelve male SD rats were randomly divided into control group(Ctrl)and CIH group(CIH), 6 rats in each group. After 6 weeks of modeling, the effect of CIH on mGluR1/ 5 protein level was detected by Western blotting, the expression and distribution of mGluR1/ 5 in SCG were detected by immunohistochemistry and double-immunofluorescent staining. Results mGluR1/ 5 was expressed in rat SCG. mGluR1 was distributed in neurons and small intensely fluorescent (SIF) cells, but not in satellite glial cells (SGCs), nerve fibers and blood vessels, whereas mGluR5 was mainly distributed in nerve fibers and a little in neurons, but not in SGCs, SIF cells and blood vessels. CIH increased the protein levels of mGluR1/ 5 (P<0. 01) in rat SCG. Conclusion Both mGluR1 and mGluR5 are expressed in the rat SCG, but their distribution are different, and the increased protein levels of both may be involved in CIH-induced hypertension.

Characterization of metabotropic glutamate receptor 7 and 8 in rat superior cervical ganglion and their changes following chronic intermittent hypoxia / 南方医科大学学报

OBJECTIVE@#To investigate the expression and localization of metabotropic glutamate receptors 7 and 8 (mGluR7/8) in rat superior cervical ganglion (SCG) and their changes in response to chronic intermittent hypoxia (CIH).@*METHODS@#We detected the expressions of mGluR7 and mGluR8 in the SCG of 8-week-old male SD rats using immunohistochemistry and characterized their distribution with immunofluorescence staining. The expression of mGluR7 and mGluR8 in the cytoplasm and nucleus was detected using Western blotting. A 6-week CIH rat model was established by exposure to intermittent hypoxia (6% oxygen for 30 s followed by normoxia for 4 min) for 8 h daily, and the changes in systolic blood pressure, diastolic blood pressure and mean arterial pressure were measured. The effect of CIH on expression levels of mGluR7 and mGluR8 in the SCG was analyzed using Western blotting.@*RESULTS@#Positive expressions of mGluR7 and mGluR8 were detected in rat SCG. mGluR7 was distributed in the neurons and small fluorescent (SIF) cells with positive staining in both the cytoplasm and nuclei, but not expressed in satellite glial cells (SGCs), nerve fibers or blood vessels; mGluR8 was localized in the cytoplasm of neurons and SIF cells, but not expressed in SGCs, nerve fibers, or blood vessels. Western blotting of the nuclear and cytoplasmic fractions of rat SCG further confirmed that mGluR7 was expressed in both the cytoplasm and the nucleus, while mGluR8 exists only in the cytoplasm. Exposure to CIH significantly increased systolic blood pressure, diastolic blood pressure and mean arterial pressure of the rats (all P < 0.001) and augmented the protein expressions of mGluR7 and mGluR8 in the SCG (P < 0.05).@*CONCLUSION@#mGluR7 and mGluR8 are present in rat SCG but with different localization patterns. CIH increases blood pressure of rats and enhanced protein expressions of mGluR7 and mGluR8 in rat SCG.

Intermittent hypoxia can improve myocardial energy metabolism / 中华物理医学与康复杂志

Objective:To explore any effect of intermittent hypoxia (IH) on myocardial energy metabolism and its mechanism.Methods:Twenty-one male Sprague-Dawley rats were randomly divided into a sham operation group, a myocardial infarction group and an observation group. The latter two groups received occlusion of the left anterior descending coronary artery. The observation group then lived in an hypoxic environment intermittently for 4 hours/day, 5 days/week for four weeks, while the other 2 groups were exposed to a normal level of oxygen. The ejection fraction of the left ventricle (LVEF) was measured at 1 week after the modeling and 4 weeks after the start of the intervention. Also at that point myocardial fibrosis, mitochondrial structure, ATP content, and the protein expressions of adenosine monophosphate-activated protein kinase alpha1 (AMPKα1) and sirtuins protein family member 3 (SIRT3) were assessed in all three groups.Results:A significant decrease in the LVEF, the number of mitochondria, ATP content, AMPKα1 and SIRT3 protein were observed in the infarction group compared with the sham group. There was also a significant increase in the myocardial fibrosis index. Moreover, the LVEF decreased significantly and the myocardial fibrosis index had increased significantly in the observation group compared with the sham operation group, though the two groups exhibited no significant differences the number of mitochondria, ATP content, or the expression of AMPKα1 or SIRT3. Compared with the myocardial infarction group, in the observation group there was a significant increase in the LVEF, the number of mitochondria, ATP content, and the expression of AMPKα1 and SIRT3 protein, with a significant decrease in the fibrosis index. AMPKα1 and SIRT3 level were positively inter-correlated and positively correlated with LVEF and ATP content.Conclusions:IH intervention can promote ATP synthesis and improve mitochondrial structure by regulating the AMPKα1/SIRT3 pathway, reducing myocardial fibrosis and enhancing cardiac function.

Chr9∶52042693|52047844⁃miR⁃351⁃5p⁃Pten Is Involved in the Development and Progression of Obstructive Sleep Apnea Syndrome through a ceRNA Mechanism / 中国生物化学与分子生物学报

Intermittent hypoxia (IH) is an important pathophysiological feature of obstructive sleep apnea (OSA), but its molecular mechanism is still unclear. We aim to investigate the role of endogenous competing endogenous RNA (ceRNA) regulatory network in the development of IH in OSA rats. An intermittent hypoxic rat model of OSA was constructed by hypoxic and reoxygenation cycles. CircRNAs and mRNAs were detected in rat bronchial tissues, and 230 up-regulated and 181 down-regulated circRNAs and 1238 up-regulated and 608 down-regulated mRNAs were analyzed and screened. The results of Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of the differential circRNAs and mRNAs suggested that they were mainly associated with metabolic pathways and PI3K-Akt signaling pathways. The key circRNAs (the top six circRNAs with the largest differences) were further validated by quantitative real-time polymerase chain reaction (qRT-PCR), chr9:52042693| 52047844 and chr4: 64889575|64899587 were expressed in bronchial tissues consistent with the sequencing results, which were used to further construct the ceRNA regulatory network. Four potential ceRNA regulatory networks were identified by TargetScan and miRanda database, combined with the results of differential circRNA and mRNA. The expression of molecules in the four potential ceRNA regulatory networks was detected by qRT-PCR in bronchial and lung tissues, and the results suggested that the expression of this regulatory network, chr9:52042693|52047844-miR-351-5p-Pten, was consistent with the sequencing results. The findings indicate that chr9:52042693 | 52047844-miR-351-5p-Pten may be involved in the development and progression of obstructive sleep apnea syndrome through a ceRNA mechanism.

Pyroptosis mediated renal injury caused by chronic intermittent hypoxia and the intervention effect of edaravone in rats / 中国临床药理学与治疗学

AIM: To study the protective effect of edaravone on renal injury induced by chronic intermittent hypoxia and its effect on Caspase-1 mediated pyroptosis signaling pathway in rats. METHODS: Twenty four SPF male SD rats were randomly divided into normal control group, intermittent hypoxia group, intermittent hypoxia + normal saline group and intermittent hypoxia + edaravone group, with 6 rats in each group. The four groups of rats were placed in the closed feeding chamber for modeling. The oxygen concentration in the NC group was maintained at about 21%; the IH group, IH + NS group and IH + EDA group were given regular input of pure oxygen, pure nitrogen and compressed air to form anoxic-reoxygenation cycle (60 s hypoxic period + 60 s reoxygenation period). During the hypoxic period, the oxygen concentration in the chamber was reduced to 6%-7%, and the rats in the IH + EDA group were intraperitoneally injected with edaravone at a dose of 5 mg/kg per day before modeling, while the rats in the IH + NS group were intraperitoneally injected with normal saline at the same dose per day. After 8 weeks of modeling, blood and kidney tissue samples were collected to measure the levels of Crea and Urea in each group. The pathological changes and fibrosis degree of kidney were observed under light microscope after HE and Masson staining. The content of malondialdehyde (MDA) and activity of superoxide dismutase (SOD) were determined by chemical method. The expression levels of NLRP3, Caspase-1 and IL-1β in renal tissues were determined by immunohistochemical staining. The expression levels of caspase-1 and IL-1β in renal tissues were determined by Western blot. GSDMD and IL-18 mRNA were detected by RT-PCR. RESULTS: After intermittent hypoxia exposure, serum Crea and Urea were increased significantly (P < 0.01), renal tubules were damaged by pathology, collagen fiber deposition occurred in balloon space of renal units, MDA content was increased and SOD activity was decreased (P < 0.01). Caspase-1, NLRP3, IL-1β protein expression increased (P < 0.01 or P < 0.05), GSDMD mRNA and IL-18 mRNA amplification increased (P < 0.01); After Edaravone intervention, the above indexes showed a reverse trend compared with that after intermittent hypoxia exposure, and the pathological damage of kidney was reduced (P < 0.01 or P < 0.05). CONCLUSION: Chronic intermittent hypoxia may mediate kidney injury through oxidative stress activation of caspase-1 involved in the cell pyroptosis signaling pathway, while edaravone may inhibit the activation of pyroptosis signaling pathway by scavenging oxygen free radicals and down-regulating the level of oxidative stress in the body, thus playing a protective role in kidney.

Buzhong Yiqitang Reduces CIH-induced Pulmonary Inflammatory Injury by ACE2-Ang（1-7）-Mas Axis / 中国实验方剂学杂志

ObjectiveTo investigate the intervention effect of Buzhong Yiqitang （BZYQT） on pulmonary inflammation in mice induced by chronic intermittent hypoxia （CIH） and preliminarily elucidate its mechanism. MethodForty healthy male C57BL/6 mice aged 6-8 weeks were randomly divided into the following groups： normoxia group， model group （exposed to CIH）， and low-， medium-， and high-dose BZYQT groups. The normoxia group was exposed to a normoxic environment， while the model group and the low-， medium-， and high-dose BZYQT groups were exposed to intermittent hypoxia. In the BZYQT groups， the BZYQT （8.1， 16.2， 32.4 g·kg-1·d-1） was administered orally 30 min before placing the mice in the hypoxic chamber， while the model group and the normoxia group received an equivalent volume of normal saline. After five weeks of modeling， pulmonary function of the mice was measured using an EMKA animal lung function analyzer， and lung tissue samples were collected after the pulmonary function tests. Hematoxylin-eosin （HE） staining was performed to observe the histopathological changes in the lung tissue of each group. Enzyme-linked immunosorbent assay （ELISA） was used to measure the levels of interleukin-6 （IL-6）， interleukin-8 （IL-8）， tumor necrosis factor-α （TNF-α） in the serum， as well as angiotensin Ⅱ （Ang Ⅱ） and angiotensin-（1-7） ［Ang（1-7）］ in lung tissue. Western blot and immunohistochemistry were used to detect the protein expression of IL-6， IL-8， TNF-α， angiotensin-converting enzyme 2 （ACE2）， and mitochondrial assembly receptor （Mas）. ResultCompared with the normoxia group， the model group showed significant abnormalities in lung function （P<0.05， P<0.01）， lung tissue changes， such as thickening of alveolar walls and inflammatory cell infiltration， increased levels of IL-6， IL-8， TNF-α in the serum and Ang Ⅱ in lung tissue （P<0.01）， decreased level of Ang（1-7） （P<0.01）， increased protein expression of IL-6， IL-8， and TNF-α， and decreased protein expression of ACE2 and Mas （P<0.05， P<0.01）. Compared with the model group， the BZYQT groups showed improvement in lung function （P<0.05， P<0.01）， and HE staining of lung tissue showed approximately normal alveolar wall thickness and reduced inflammatory cell infiltration. Immunohistochemistry and Western blot analysis showed a significant decrease in the expression of inflammatory-related proteins （P<0.05， P<0.01）， and a significant increase in ACE2 and Mas protein expression （P<0.05， P<0.01）. ConclusionBZYQT can improve lung injury in mice exposed to CIH by regulating the ACE2-Ang（1-7）-Mas axis to inhibit inflammatory responses.

The role of NMDA glutamate receptors in lung injury caused by chronic long-term intermittent hypobaric hypoxia

Chronic intermittent hypoxia (CIH), a component of sleep apnea-hypopnea syndrome, is suggested to cause damage to lung tissue, and the role of glutamate is not well studied. We used a chronic long-term intermittent hypobaric hypoxia (CLTIHH) model of rats to find out if such procedure causes lung injury and the potential effect of N-methyl-D-aspartate receptors (NMDARs) by using receptor antagonist MK-801 (dizocilpine). Thirty-two rats were placed into four groups; a control and three CLTIHH groups where rats were placed into a low-pressure chamber set to 430 mmHg for 5 h/day, 5 days/week, for 5 weeks. Only one group received MK-801 (0.3 mg/kg, ip) daily. We evaluated tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-10, and nuclear factor (NF)-kB for the inflammatory process, superoxide dismutase (SOD), malondialdehyde (MDA), catalase (CAT), glutathione peroxidase (GPX), total antioxidant status (TAS), and total oxidant status (TOS) for oxidative stress, and caspase-9 levels. Blood plasma, bronchoalveolar fluid (BALF), and lung tissue extracts were evaluated. Both oxidant and inflammatory parameters were significantly increased in all the mediums of the CLTIHH groups except the group that received MK-801. Significant evidence was collected on MK-801 alleviating the effect of CLTIHH. Histological evaluations revealed lung damage and fibrotic changes in the CLTIHH groups. It was first shown that the CLTIHH procedure caused chronic lung injury, and that inflammation and oxidant stress were influential in the formation of lung injury. Secondly, NMDAR antagonist MK-801 effectively inhibited the development of lung injury and fibrosis.

Protective effect of 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine on lung injury with intermittent hypoxia in premature rats / 中华实用儿科临床杂志

Objective:To investigate the effects of 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine (Tempol) on the expressions of hypoxia inducible factor-1 α (HIF-1α)/vascular endothelial growth factor (VEGF) and lung development in premature neonatal rats under intermittent hypoxia (achieved by supplying a low concentration of oxygen).Methods:The intermittent hypoxia model was established.Caesarean section of rats was performed at 21 days of gestation when the fetal rats were estimated to be in labor.A total of 192 premature neonatal rats survived and were randomly divided into 6 groups according to random number table method: air control+ saline group, air control+ Tempol group, constant oxygen + saline group, constant oxygen + Tempol group, intermittent hypoxia + saline group, and intermittent hypoxia + Tempol group, 32 rats in each group.On the 7 th, 14 th and 21 st day of birth, the lung tissues of 8 neonatal preterm rats in each group were taken.Malondialdehyde (MDA) and total antioxidant capacity (TAOC) were detected by chemical analysis.The mRNA and protein levels of HIF-1α and VEGF were detected by real-time fluorescence quantitative PCR (qPCR) and immunohistochemistry, respectively.Another 8 neonatal rats in each group were taken for pulmonary function test on the 21 st day after birth. One- way ANOVA and SNK- q test were used for comparison among and between groups, respectively. Results:Compared with the constant oxygen + saline group, the intermittent hypoxia + saline group showed mild pulmonary septal thickening, increased MDA, decreased TAOC, elevated mRNA and protein expression levels of VEGF and HIF-1 α, and decreased lung function indexes.The differences were statistically significant (all P<0.05). Compared with the corresponding saline group, the intermittent hypoxia + Tempol group had decreased MDA and increased TAOC, and the differences were statistically significant at 14 d[MDA(3.09±0.45) nmol/(mg·pr) vs.4.02±0.30) nmol/(mg·pr), TAOC(3.13±0.31) U/(mg·pr) vs.(2.44±0.22) U/(mg·pr)]and 21 d[MDA(2.87±0.43) nmol/(mg·pr) vs.(4.47±0.56) nmol/(mg·pr), TAOC(3.47±0.35) U/(mg·pr) vs.(2.31±0.32) U/(mg·pr)] (all P<0.05). Compared with the corresponding saline group, the mRNA and protein expression of HIF-1 α and VEGF decreased in the intermittent hypoxia+ Tempol group, and the decrease in the mRNA expression of HIF-1 α was statistically significant at 14 d (2.11±0.60 vs.2.88±0.59) (all P<0.05). Lung function indexes, including tidal volume[(0.41 ± 0.01) mL vs.(0.36±0.02) mL], minute respiratory ventilation[(35.48 ± 2.95) mL vs.(30.62±2.27) mL], maximum expiratory flow[(2.19 ± 0.19) mL/s vs.(1.51±0.19) mL/s]and dynamic lung compliance[(2.65 ± 0.40) mL/cmH 2O vs.(1.83±0.34) mL/cmH 2O, 1 cmH 2O=0.098 kPa]increased (all P<0.05). Conclusions:Tempol can alleviate the lung injury induced by intermittent hypoxia under the intervention of a low concentration of oxygen to premature newborn rats and improve their lung function.

Rehabilitation of Moderate Intermittent Hypoxia on Clinical Related Diseases (review) / 中国康复理论与实践

Objective:To systematically review the rehabilitation effects of moderate intermittent hypoxia on clinical related diseases. Methods:Literatures about rehabilitation effects of moderate intermittent hypoxia on clinical related diseases from 2004 to 2021 were searched in PubMed, ScienceDirect, CNKI and Wanfang databases using a systematic review method. Results:A total of 27 literatures were included, which focused on the effects on neural system, respiratory system, and cardiovascular diseases, as well as the regulation of metabolic and the improvement of exercise ability. Conclusion:Moderate intermittent hypoxia could improve the cognitive function, alleviate the symptoms of ischemic stroke, accelerate the recovery of spinal cord injury, resist depression and reduce blood pressure; regulate metabolism, improve aerobic capacity, enhance respiratory function and myocardial function. However, more researches are needed to make it clear that the standard on the duration of hypoxia within episodes, the number of hypoxia/reoxygenation cycles (episodes) per session every day, the pattern of presentation, and the cumulative duration of exposure.

Astragaloside IV alleviating chronic intermittent hypoxia-induced cardiac injury by enhancing autophagy / 解剖学报

Objective To investigate the protective effects of astragaloside IV (AS IV) on chronic intermittent hypoxia (CIH) -induced cardiac injury. Methods Twenty-four male adult Sprague Dawley rats were randomly assigned to control, CIH, CIH+ASIV, and ASIV group, 6 rats in each group. Circular nitrogen and oxygen were filled to make oxygen concentration change between 9%-21% for the CIH treated rats. The exposure cycle was repeated every 3 minutes, 8 hours/ day for 35 days. ASIV was given by intragastric administration daily before intermittent hypoxia exposure in the CIH+ASIV group and AS IV group. The control group and CIH group were given normal saline of the same quantity. Echocardiography was used to analyse cardiac function. Myocardial structure was assessed by HE and wheat germ agglutinin staining. The apoptosis of cardiomyocytes was detected by TUNEL assay. The levels of superoxide dismutase (SOD) and malondialdehyde (MDA) in heart were detected by commercial kits. Western blotting was used to evaluate the levels of Bcl-2, Bax, LC3, Beclinl, P62, and mammalian target of rapamycin (mTOR). Results In the CIH group, the left ventricular ejection fraction (LVEF) and left ventricular internal diameter at end-systole (LVIDs) were inhibited, the myocyte cells showed disordered arranged, enlarged diameters and higher apoptosis rate. The MDA content was significantly elevated and the SOD activity decreased in CIH group when compared with those of control. What's more, the expression level of Beclin 1 decreased while the P62 expression and the p-mTOR/mTOR ratio increased in the CIH group. Compared with the model group, the LVEF, LVIDs, SOD activity, LC3 H / I ratio, and Beclinl expression of rats in the CIH + AS IV group increased. The cardiomyocytes in the rats of CIH + ASIV group showed normal arrangement and diameters. The apoptosis rate, MDA content, P62 expression and the p-mTOR/mTOR ratio decreased in the CIH+ASIV group when compared with the CIH group. Conclusion AS IV can alleviate CIH-induced cardiac injury by promoting autophagy via mTOR.

Adiponectin Ameliorated Pancreatic Islet Injury Induced by Chronic Intermittent Hypoxia through Inhibiting the Imbalance in Mitochondrial Fusion and Division / 中国医学科学杂志(英文版)

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

Altitude effect on sleep quality and serum melatonin levels in Chilean mining workers / Efecto de la Altitud en la calidad de sueño y niveles séricos de melatonina en trabajadores mineros en Chile

High altitude (HA) mining operations are a very important business in Chile, but reduced availability of oxygen affects the sleep quality, increasing the risk of accidents. An important regulator of sleep-wake cycle is the hormone Melatonin, produced by pineal gland as a sleep inductor. The aim of this study is to evaluate the effect of high altitude (4,500 m) on the quality of sleep of workers undergoing to Chronic Intermittent Hypobaric Hypoxia (CIHH) using self-reported surveys of sleepiness and sleep quality, measurement of sleep apnea (using nocturnal oximetry) and serum levels of melatonin. The Desaturation index (ID4) results revealed higher HA scores compared to sea level (SL). Regarding melatonin levels, the results show that it is increased in HA versus SL and this increase would be related to oxygen saturation during sleep. These data link sleep quality in HA to its melatonin levels, suggesting that melatonin may be a potential biomarker for sleep quality.

Effect of cyclic intermittent hypoxia on the expression of β-site amyloid precursor protein cleaving enzyme 1 in rat adrenal gland / 解剖学报

Objective To observe the expression and localization of β-site amyloid precursor protein cleaving enzyme 1 (BACE1) in rat adrenal gland and to detect the effect of cyclic intermittent hypoxia (CIH) on the expression of BACE1. Methods The expression and localization of BACE1 in rat adrenal gland were detected by Western blotting and immunohistochemistry. Sixteen male Sprague-Dawley (SD) rats were randomly divided into two groups: control group and CIH group, 8 rats in each group. The protein levels of BACE1 and tyrosine hydroxylase (TH) in rat adrenal medulla were detected by Western blotting after CIH 2 weeks treatment. Results BACE1 was mainly localized in rat adrenal medullary nerve fibers. Compared with the control group, BACE1 protein level decreased and TH protein level increased in the adrenal medulla in the CIH group. Conclusion BACE1 is located in rat adrenal medullary nerve fibers. The decreased level of BACE1 may participate in slowing down the excessive enhancement of sympathetic activity induced by CIH.

Effect of beta-carotene on learning, memory and expression of caspase-3 and phosphorylated tau in hippocampus of rats with obstructive sleep apnea syndrome / 临床神经病学杂志

Objective To observe the effect of β-carotene ( β-C ) on the learning and memory and the expression of caspase-3 and p-tau expression in hippocampus of obstructive sleep apnea syndrome ( OSAS) rats. Methods Twenty-four adult SD rats were randomly divided into normal control group, OSAS model group ( model group) and β-C intervention group (intervention group), with 8 rats in each group. A hypoxic chamber was used to establish an OSAS rat animal model. The rats in model group and intervention group were given by gavage before intragastric administration, and no treatment was performed in the normal group. After completion of the modeling, the Morris water maze was used to test the learning and memory ability of the experimental rats. Observing the pathological changes of hippocampal tissue in rats by HE staining. The protein expression of caspase-3 and p-tau in hippocampus was detected by Western Blotting. Results Escape latency time of model group in each time point were significantly prolonged than those in normal control group ( all P<0. 05), and escape latency time of intervention group at 2-5 d were significantly shorter than those in model group (all P<0. 05). The number of times of crossing the platform in model group was significantly less than that in normal control group and intervention group ( all P<0. 05). Compared with those in model group, the expression of caspase-3 and p-tau in normal control group and intervention group were significantly lower (all P<0. 05). Conclusion β-C can reduce the impairment of learning and memory ability caused by OSAS, and the mechanism may be related to its inhibition of caspase-3 and p-tau protein expression.

The influence of chronic intermittent hypoxia on hypothalamic-somatotropic axis in rats / 中华内科杂志

Objective To investigate the effects of chronic intermittent hypoxia on somatotropic axis hormone levels in rats.Methods Mature male Wistar rats were exposed to air or intermittent hypoxia randomly.The serum levels of growth hormone-releasing hormone (GHRH),growth hormone (GH) and somatostatin (SS) were measured before exposure,at the 4th,8th,and 12th week after exposure.Different hormone levels in two groups were compared and analyzed.Results Compared with the control group,GHRH levels in chronic intermittent hypoxic group showed a significant decline at the 4th week [(732.77± 46.99)pg/ml vs.(893.59±40.00) pg/ml,P＜0.05],while SS levels at the 8th week [(30.71 ±2.27) pg/ml vs.(44.69±3.36) pg/ml,P＜0.05] and GH levels at the 12th week [(1.20±0.29) ng/ml vs.(2.06±0.13) ng/ml,P＜0.05]were similarly reduced.As the duration of intermittent hypoxia was prolonged,the GHRH levels did not decrease further [4th week (732.77±46.99) pg/ml vs.8th week (607.54± 131.61) pg/ml vs.12th week (730.05±40.63) pg/ml,P＞0.05].However,the serum SS levels decreased further from the 8th week to the 12th week [(30.71±2.27) pg/ml vs.(24.41±4.06) pg/ml,P＜0.05].Conclusion Chronic intermittent hypoxia might inhibit the function of somatotropic axis.Hypothalamic hormones are the earlyonesto be influenced,thereafter the entire axis.

Protective effect of Rhodiola rosea on vascular endothelium in rats with intermittent hypoxia / 中国中西医结合急救杂志

Objective To observe the protective effect of Rhodiola rosea on vascular endothelium in rats with intermittent hypoxia (IH) and to explore its possible mechanism. Methods According to random number table method, 45 male Sprague-Dawley (SD) rats were divided into normal control group, IH group and Rhodiola rosea low, medium and high dose groups, with 9 rats in each group. The IH model was reproduced by putting the rats into IH model chamber, and then feeding them with nitrogen, oxygen and compressed air for 45 days. The feeding bin and feeding time of rats in the normal control group were consistent with those in other groups, and the oxygen concentration in the tank was maintained at 20%-21%. The rats in Rhodiola rosea high, medium and low dose groups were intraperitoneally injected with Rhodiola rosea (0.2, 0.1 and 0.05 mL/100 g), starting from the 15 th day in IH chamber, and the injection continued for 30 days. The levels of malondialdehyde (MDA), superoxide dismutase (SOD) and nitric oxide (NO) in the coronary arteries of rats in each group were detected by automatic biochemical analyzer. The contents of coronary hypoxia-inducible factor-1α(HIF-1α) and tumor necrosis factor-α(TNF-α) in rats were determined by enzyme linked immunosorbent assay (ELISA). The mRNA expression levels of endothelin-1 (ET-1) and vascular endothelial growth factor (VEGF) in coronary artery tissues of rats in each group were measured by reverse transcription-polymerase chain reaction (RT-PCR). The pathological changes of aorta in each group were observed under light microscope. Results Compared with the normal control group, SOD and NO in the IH group decreased [SOD (U/mg): 4.43±0.22 vs. 8.60±0.34, NO (μmol/g): 3.09±0.07 vs. 4.81±0.41, both P < 0.01], MDA, TNF-α, HIF-1α and mRNA expression of ET-1 and VEGF increased [MDA (nmol/mg): 0.78±0.03 vs. 0.50±0.03, TNF-α(pg/mg): 6.35±0.29 vs. 3.27±0.14, HIF-1α (ng/mg): 14.55±0.70 vs. 7.16±0.17, ET-1 mRNA (2-ΔΔCt): 1.75±0.03 vs. 1.10±0.07, VEGF mRNA (2-ΔΔCt):4.38±0.10 vs. 1.20±0.07, all P < 0.01]. Compared with the IH group, SOD and NO were increased in three Rhodiola rosea groups, MDA, TNF-α, HIF-1α and mRNA expression of ET-1 and VEGF were decreased in three Rhodiola rosea groups, and the changes in the Rhodiola rosea high dose group were more significant than those in the low and medium dose Rhodiola rosea groups [SOD(U/mg): 7.47±0.19 vs. 5.41±0.37, 6.71±0.28, MDA (nmol/mg): 0.57±0.20 vs. 0.74±0.04, 0.70±0.03, NO (μmol/g): 4.00±0.28 vs. 3.27±0.18, 3.47±0.28, TNF-α(pg/mg): 3.90±0.17 vs. 5.08±0.27, 4.39±0.26, HIF-1α(ng/mg): 8.40±0.23 vs. 11.07±0.41, 9.81±0.44, ET-1 mRNA (2-ΔΔCt): 1.12±0.04 vs. 1.71±0.03, 1.63±0.07, VEGF mRNA (2-ΔΔCt): 2.45±0.09 vs. 3.99±0.12, 3.27±0.08, all P < 0.05]. Under light microscope, the inner membrane of the normal control group was intact, and the endothelial cells were loose and slightly stained on the surface of the inner membrane; in the IH group, part of the arterial areas showed endointima edema or even abscission, and interstitial edema in the vascular wall. The pathological changes in three Rhodiola rosea groups were less than that in the IH group, and the changes of Rhodiola rosea high dose group were more significant. Conclusion Rhodiola rosea can protect the vascular endothelium caused by IH exposure through improving the level of anti-hypoxia in tissues and inhibiting oxidative stress and inflammatory response.

Mechanism of endothelin-1 mediated the cyclic intermittent hypoxia on carotid body plasticity in rats / 解剖学报

Objective To investigate the potential molecular mechanism of endothelin-1 (ET-1) involved in cyclic intermittent hypoxia (CIH) induced carotid body chemoreceptor plasticity. Methods (1) Animal experiment: 32 male Sprague-Dawley (SD) rats were randomly divided into two groups: Control group (Con) and CIH group (CIH), 16 rats per group. After 21 days of CIH exposure, each group (Con and CIH) was subdivided into 2 groups: Lail vein injection of ET-1 (1 x 10~6 mol/kg body weight) or same volume of saline according to the above dose. After 30 minutes of injection, carotid bodies were collected and Western blotting was used to detect the change of tested proteins. (2) Carotid body organ culture: Rat carotid bodies were isolated and cultured in the incubator, and treated with ET-i (lxlO"4 mol/L) for different times (0 minute, 10 minutes, 60 minutes). The effect of ET-1 on the phosphorylation of p38 mitogen-activated protein l kinase (p38 MAPK) was detected by Western blotting. Results (1) CIH increased the protein level of endothelin receptor A (ET-A)and ET-B in the rat carotid body. (2) Compared with the ET-1 injected Con group, phosphorylated protein kinase A (p-PKA), p-p38 MAPK, phosphorylated Ca2;/calmodulin-dependent protein kinase D (p-CaMK II) and phosphorylated cAMP response element-binding protein (p-CREB) and RhoA protein level were significantly up-regulated in ET-1 injected CIH rats. (3) Application of ET-1 to organ cultured carotid bodies resulted in the elevation of p-p38 MAPK in a time-dependent manner. Conclusion ET-1 may regulate CIH-induced carotid body chemoreflex plasticity through PKA/p38 MAPK/CaMK II/CREIJ and IthoA signaling.

Intervention effects and mechanism of Chinese herbal medicine of supplementing Qi and activating blood circulation on chronic intermittent hypoxia composite insulin resistance ApoE~(-/-) mice model / 中国中药杂志

This study aims to observe the intervention effects of Chinese herbal medicine of supplementing Qi and activating blood circulation on chronic intermittent hypoxia(CIH) composite insulin resistance(IR) mediated atherosclerosis(AS) mice model,and to observe the mechanism of SREBP-1 c signaling molecule.IR Apo E-/-mice model was induced by high-fat diet combined with STZ injection.Then the mice were treated with hypoxic animal incubator for 8 h per day and 8 weeks to establish a CIH+IR-ApoE-/-mouse model.Model mice were randomly and averagely divided into normoxic control group(NC),model group(CIH) and SREBPs inhibitor group(betulin),atorvastatin group(WM),TCM low-dose group(TCM-L),TCM middle-dose group(TCM-M) and TCM high-dose group(TCM-H) group.Chinese herbal medicine of supplementing Qi and activating blood circulation including ginsenosides combined with ligustrazine(TMP) were used as intervention drugs.The study observed the effect of drugs on IR,serum lipid,inflammation,stress,AS and SREBP-1 c related molecules.The results showed that fasting blood glucose in TCM-H group decreased compared with other experimental groups(P<0.05).HDL-C level in betulin group,WM group,TCM-H group was higher than that in CIH group(P<0.05).LDL-C level in TCM-M group,TCM-H group is lower than that in CIH group(P<0.05).The level of CRP in CIH group was higher than that in other groups(P<0.05).The level of SOD in TCM-H group was higher than that in CIH group(P<0.05).NC group and CIH group showed obvious AS aortic plaque,while betulin group,WM group,TCM-H group showed reduction in AS plaque(P<0.05).For descending aorta,AS plaque in CIH group was multiple and large,while less and smaller in WM group and TCM-H(P<0.05).The expression of SREBP-1 c and FAS in aorta and skeletal muscle in TCM-H group was lower than that in CIH group(P<0.05).In aorta,the expression of TNF-α and CD106(VCAM-1) was lower in TCM-H group than that in CIH group(P<0.05).In aorta,skeletal muscle and liver,the level of p-IRS-1 in TCM-H group was significantly higher than that in CIH group(P<0.05).In aorta and liver,the expression of HIF-1α in TCM-H group was lower than that in CIH group(P<0.05).The study demonstrated that combination ginsenosides with TMP could improve IR and serum lipid level and inhibit inflammation and oxidative stress as well as ultimately alleviate AS to some extent.And the mechanism of its interventional effects might be related to the inhibition of CIH-induced upregulation of SREBP-1 c related molecules.

Effects of Antioxidant Tempol on Systematic Inflammation and Endothelial Apoptosis in Emphysematous Rats Exposed to Intermittent Hypoxia

PURPOSE: Obstructive sleep apnea and chronic obstructive pulmonary disease are independent risk factors of cardiovascular disease (CVD), and their coexistence is known as overlap syndrome (OS). Endothelial dysfunction is the initial stage of CVD; however, underlying mechanisms linking OS and CVD are not well understood. The aim of this study was to explore whether OS can lead to more severe inflammation and endothelial apoptosis by promoting endothelial dysfunction, and to assess the intervention effects of antioxidant tempol. MATERIALS AND METHODS: Male Wistar rats (n=66) were exposed to normal oxygen [normal control (NC) group], intermittent hypoxia (IH group), cigarette smoke (CH group), as well as cigarette smoke and IH (OS group). Tempol intervention was assessed in OS group treated with tempol (OST group) or NaCl (OSN group). After an 8-week challenge, lung tissues, serum, and fresh blood were harvested for analysis of endothelial markers and apoptosis. RESULTS: The levels of intracellular adhesion molecule-1, vascular cellular adhesion molecule-1, and apoptosis in circulating epithelial cells were the highest in OS group and the lowest in NC group. These levels were all greater in IH group than in CH group, and were lower in OST group than in OS and OSN groups (all p < 0.001). CONCLUSION: Synergistic effects of IH with cigarette smoke-induced emphysema produce a greater inflammatory status and endothelial apoptosis. OS-related inflammation and endothelial cell apoptosis may play important roles in promoting cardiovascular dysfunction, and antioxidant tempol could achieve a partial protective effect.

Improvement of hydrogen on liver oxidative stress injury in chronic intermittent hypoxia rats / 中国应用生理学杂志

OBJECTIVE@#To explore the effects of hydrogen on liver injury in chronic intermittent hypoxia rats and the related oxidative stress mechanism.@*METHODS@#Twenty-four male adult SD rats were randomly divided into 3 groups(=8):the normoxia group (Norm), the chronic intermittent hypoxia group (CIH), the chronic intermittent hypoxia and hydrogen group (H + CIH). Rats in Norm group were exposed in air, those in the other 2 groups suffered from chronic intermittent hypoxia conditions for 5 weeks. Before the CIH treatment, rats in H+CIH group inhaled hydrogen gas at 67% concentration for 1 hour. The serum biochemical indicators of oxidative stress, pro-inflammatory cytokine, liver enzyme and blood lipid were inspected after five weeks treatment, the pathological changes of liver tissue were also observed in the transmission electron microscope.@*RESULTS@#Compared with Norm group, the microstructure of liver cells was severely injured, and the serum levels of glutamic-pyruvic transaminase(ALT),glutamic-oxalacetic transaminase (AST) were significantly higher in CIH group (<0.05); the serum level of 8-hydroxy-2 deoxyguanosine(8-OHdG) and interleukin-6(IL-6) was significantly higher, the serum level of superoxide dismutase (SOD) was significantly lower. Compared with CIH group, the pathology of liver microstructure were significantly improved and the serum levels of ALT, AST were significantly lower in H+CIH group (<0.05); the serum levels of 8-OHdG and IL-6 were significantly lower, the serum level of SOD was significantly higher. Compared with Norm group, the serum level of IL-1 was higher, the serum level of TC, TG, and low density lipoprotein(LDL) were lower, but there was no statistical difference with those in CIH group. There was no statistical difference in the serum level of high density lipoprotein (HDL)among the three groups.@*CONCLUSIONS@#Pre-treatment with hydrogen could improve the liver injury caused by chronic intermittent hypoxia, and reducing oxidative stress level for protecting the liver cells damage.