Intermittent hypobaric hypoxia causes deleterious effects on the reproductive system in female rats.

BACKGROUNDS: Numerous studies have revealed that hypobaric hypoxia exposure elicited imbalance of homeostasis. However, the effects of intermittent hypobaric hypoxia (IHH) exposure on the female reproductive system have been rarely reported. This study aims to assess the effects of IHH on rat female reproductive system and explore the corresponding mechanism at the histological, endocrine and molecular levels. METHODS: The female rats were randomly divided into control and IHH groups. Multiple pathophysiological parameters, including body weight gain, organ coefficients, estrus cycle, and health signs were measured. Also, the reproductive hormones, hormone receptor mRNA expression and oxidant/antioxidant level were evaluated. RESULTS: Significant increases of the heart, liver and lung coefficients were observed after IHH exposure. There were no statistically significant differences in ovarian and uterine coefficients, but changes were found in the morphology of the ovary and uterus. Additionally, the diestrus phase duration was significantly increased during IHH exposure. Furthermore, estrogen increased and the Luteinizing hormone and progesterone decreased after IHH exposure. Altered expression of ER, PR and LHR were also found in the IHH exposed rats. Importantly, IHH exposure significantly repressed the activities of GSH-Px and T-SOD and improved the contents of MDA. CONCLUSIONS: Our results evince that IHH exposure caused estrus cycle irregularity. IHH induced oxidative stress along with ovarian and uterine structure damages, reproductive hormone disturbances and unusual expression of hormone receptors, thus suggesting a potential mechanism underlying IHH-induced reproductive system dysfunction.

Quantitative Proteomics Reveals the Effects of Resveratrol on High-Altitude Polycythemia Treatment.

High-altitude polycythemia (HAPC) is a common plateau chronic disease in which red blood cells are compensatory hyperproliferative due to high altitude hypoxic environment. HAPC severely affects the physical and mental health of populations on the plateau. However, the pathogenesis and treatment of HAPC has been rarely investigated. Here, the hypoxia-induced HAPC model of rat is established, in which hemoglobin concentration significantly increases and platelets clearly decrease. The effect of resveratrol upon hypoxia enables HAPC remission and makes hemoglobin and platelet tend to a normal level. Furthermore, quantitative proteomics is applied to investigate the plasma proteome variation and the underlying molecular regulation during HAPC occurrence and treatment with resveratrol. Hypoxia promotes erythrocyte developing and differentiating and disrupts cytoskeleton organization. Notably, the resveratrol administration reverses the proteome change pattern due to hypoxia and contributes to plateau adaption. Quantitative verification of differentially expressed proteins confirms the roles of resveratrol in HAPC. Resveratrol is expected to be useful for HAPC treatment.

Downregulation of miR-541 induced by heat stress contributes to malignant transformation of human bronchial epithelial cells via HSP27.

Environmental factors are one of the important factors affecting the occurrence of lung cancer. However, few studies have been done on the relationship between hot environment and lung cancer. In the present study, we demonstrated that heat stress leads to anchorage-independent proliferation, mitochondrial apoptosis, and autophagy of Beas-2B cells, which are normal lung bronchial epithelial cells. Heat shock protein 27 (HSP27) promoted heat stress-induced anchorage-independent proliferation and autophagy, but suppressed mitochondrial apoptosis, indicating that HSP27 might act as an oncogene in the malignant transformation of lung epithelial cells. We also showed that HSP27 promoted autophagy of these cells under heat stress via autophagy related 7 (ATG7) and ETS Transcription Factor ELK1 (ELK1), a transcription factor of ATG7, under heat stress. In addition, we showed that HSP27 translation could be repressed by microRNA miR-541, and the biological effects of miR-541 were the opposite to HSP27, suggesting that HSP27 is a downstream target of miR-541. In this study, we characterized a new mechanism whereby HSP27 promotes cell transformation during the onset of lung cancer. Our studies provide new insights into the molecular mechanisms underlying the lung carcinogenic effect of heat exposure. Specifically, heat stress promotes translation of HSP27 by inhibiting miR-541 accumulation, ultimately resulting in activation of autophagy, inhibition of mitochondrial apoptotic pathway and malignant transformation of Human Bronchial Epithelial Cells. This study identifies miR-541 as a potential prognostic biomarker or therapeutic target to improve theory of environmental carcinogenesis.

PASS: A Proteomics Alternative Splicing Screening Pipeline.

Alternative splicing (AS) has been well-investigated at the trancriptome level by the application of RNA-seq technology. There is an ongoing debate on the biological importance of AS to proteome complexity. A toolkit for accurately identifying AS from proteome data is urgently needed. Here, a software called PASS is developed to comprehensively detect AS events for the proteomics mass spectrometry (MS) data. Moreover, PASS is well compatible with MS identification by the proteogenomics approach, which provides novel AS candidates for proteome identification. The workflow of PASS mainly contains five core steps: transcripts reconstruction from RNA-Seq data, novel protein sequence generation, MS data searching, proSAM file formatting, and AS detection. Access to the program from either step is supported. PASS is successfully applied to proteome data of mouse hepatocytes and 407 AS events are first identified with proteomics MS evidences. PASS is expected to be widely used to identify AS events on proteome data and provide a deeper understanding of the proteome isoforms. The PASS software is freely available at https://github.com/wupengomics/PASS.

Epigenetic upregulation of miR-126 induced by heat stress contributes to apoptosis of rat cardiomyocytes by promoting Tomm40 transcription.

TOMM40 is the channel-forming subunit of a translocase of the mitochondrial outer membrane (TOM) that is essential for protein transport into mitochondria. TOMM40 plays an important role in maintaining normal mitochondrial function. The correlation between occupational thermal exposure and mitochondria dysfunction has been demonstrated; however, nothing is known about the alteration and role of TOMM40 in response to environmental heat stress. In the present study, we showed that environmental thermal exposure upregulated microRNA miR-126, consequently reducing AU-rich element RNA-binding protein 1 (AUF1)-mediated SP1 mRNA degradation and increasing TOMM40 transcription, which in turn decreased the mitochondria membrane potential and apoptosis of cardiomyocytes. Mechanistically, miR-126 upregulation was attributed to heat stress-induced promoter demethylation via elevated TET2 (Tet methylcytosine dioxygenase 2) expression, while SP1 mRNA degradation was caused by decreased translation of AUF1 induced by miR-126. Moreover, TOMM40 transcription was upregulated via increasing its transcription factor SP1 resulting from AUF1 inhibition in the heat stress responses. The results of the present study increased our understanding of the role of miR-126 and TOMM40 in heat stressed cardiomyocytes.

[Effects of soybean isoflavones on the energy metabolism of swimming mice].

OBJECTIVE: To establish an animal model for loaded swimming, so as to investigate the energy metabolism effects of soybean isoflavones (SI) on swimming mice. METHODS: Thirty male Kunming mice were randomly divided into three groups:normal control, swimming group, and swimming+SI group. The normal control group mice were fed a basic AIN-93M diet, the SI groups were supplied with soybean isoflavones(4 g/kg).Two weeks later, the mice were forced to swim for an hour,and then all the mice were killed, the samples of blood, liver and muscles of hind were collected.The serum contents of lactic acid(Lac), the activities of lactic dehydrogenase (LDH), succinate dehydrogenase (SDH), creatine kinase (CK) and ATPase were measured. RESULTS: Compared with normal control,the serum content of Lac was significantly improved in the group of the swimming control and SI(P<0.05),the activity of LDH in the serum was obviously improved in the group of the swimming control and SI, and the activity of CK and SDH were both significantly improved in the group of the swimming control and SI except the activity of SDH in the liver of the group SI; compared with the swimming control,the serum contents of Lac,the activities of LDH, ATPase, SDH, CK were obviously improved(P<0.05). CONCLUSIONS: Soybean isoflavones can improve the energy metabolism,antioxidant capacity of the swimming mice.

Therapeutic Efficacy of Methazolamide Against Intermittent Hypoxia-Induced Excessive Erythrocytosis in Rats.

Zhang, Zhiqing, Zhonghai Xiao, Bingnan Deng, Xiaohua Liu, Wei Liu, Hongjing Nie, Xi Li, Zhaoli Chen, Danfeng Yang, and Ruifeng Duan. Therapeutic efficacy of methazolamide against intermittent hypoxia-induced excessive erythrocytosis in rats. High Alt Med Biol 19:69-80, 2018.-This study aimed to determine whether methazolamide is effective for the treatment of chronic mountain sickness. Forty-eight male Wistar rats were randomly divided into eight groups: normoxia control, hypoxia control, hypoxia + acetazolamide (30 mg·kg-1·d-1), and five hypoxia + methazolamide groups (5, 10, 30, 90, and 120 mg·kg-1·d-1). Excessive erythrocytosis was induced through 4 weeks of hypobaric hypoxia (8 hours O2 10%/16 hours O2 21%). Rats were then treated for 4 weeks, and their body weight was measured. Hematological, hemorheological, and biochemical parameters were analyzed. Renal hypoxia-inducible factor-1alpha (HIF-1α) and vascular endothelial growth factor (VEGF) levels were detected by immunohistochemistry. Proteomic analysis of plasma was conducted to determine the most differentially expressed proteins. Methazolamide with doses lower than 30 mg·kg-1·d-1 had no significant effects on body weight compared with the hypoxia control group (p > 0.05). Methazolamide dose-dependently reduced the hemoglobin concentration, hematocrit (Hct), and blood viscosity. Hct/blood viscosity, an oxygen delivery index, dose-dependently increased after methazolamide treatment. A methazolamide dose of 10 mg·kg-1·d-1 showed similar efficacy to an acetazolamide dose of 30 mg·kg-1·d-1 for all the above parameters. Plasma levels of low-density lipoprotein cholesterol, total cholesterol, creatinine, and hemoglobin increased substantially after long-term hypoxia, but decreased after methazolamide treatment. HIF-1α and VEGF both increased substantially after long-term hypoxia and decreased in the kidney after methazolamide treatment. The most differentially expressed protein was haptoglobin, an endogenous protective factor, which was depleted in rats with excessive erythrocytosis and increased substantially after methazolamide treatment. In summary, methazolamide exhibits dose-dependent efficacy for the treatment of excessive erythrocytosis induced by long-term hypoxia. It also has beneficial effects on oxygen transport and lipid metabolism, which are encouraging with regard to the development of methazolamide-based chronic mountain sickness therapies.

Diazoxide protects rat vascular endothelial cells against hypoxia and cold-induced damage.

The present study aimed to examine the effects of hypoxia and cold on vascular endothelial cells (VECs), as well as the protective ability of novel VECs-protective drugs against these injuries. A rat model simulating exposure to hypoxia and cold at high altitude environments was established. Based on these animal experiments, rat aortic VECs were established as injury models and exposed to hypoxia and/or adrenaline (ADR) in vitro. The results revealed that hypoxia significantly altered the levels of nitric oxide and vascular endothelial growth factor, while the cold temperature significantly increased the release of ADR and noradrenaline. Exposure to hypoxia combined with cold temperature significantly affected all these indices. In vitro experiments demonstrated that hypoxia, ADR (which was used to simulate cold in the animal experiments) and the combination of the two factors resulted in damage to the VECs and endothelial dysfunction. In addition, the results also showed that diazoxide, a highly selective mitoKATP opener, protected VECs against these injuries. In conclusion, hypoxia and cold temperature induced endothelial cell dysfunction and endocrine disorders, respectively. Improving endothelial function using diazoxide may be an effective therapeutic strategy in patients with altitude-associated disorders. However, the potential for clinical application requires further study.

The physiological effects of resveratrol and its potential application in high altitude medicine.

Resveratrol, as a natural polyphenolic compound, has a wide range of beneficial effects, which includes anti-tumor, cardiovascular protection, anti-oxidant and estrogen-like effects, and so on. Its various physiological properties are closely related to the therapeutic principle for prevention and treatment of high altitude hypoxia injury. Resveratrol may play an important role in relieving or curing high altitude diseases, especially high altitude polycythemia(HAPC). However, the literature about study and application of resveratrol in plateau medicine field is rarely reported up to now. In this review, we summarized the physiological effects of resveratrol, discussed the possible main principle of resveratrol for HAPC therapy, and looked forward to resveratrol's perspective or potential application in high altitude medicine.

A rat model of high altitude polycythemia rapidly established by hypobaric hypoxia exposure.

OBJECTIVE: To investigate the effects of simple hypobaric hypoxia on parameters of hematology and blood rheology in order to establish a rat model of simulated high altitude polycythemia (HAPC) for the study of pathophysiologic mechanisms and medical prevention and treatment of HAPC. METHODS: Forty-eight male Wistar rats were randomly divided into three normal control groups and three hypoxia model groups. Normal control group rats were bred in normoxia conditions, and hypoxia group rats were subjected to hypoxic exposure for 8 hours per day at simulated 5 500 m high altitude in a hypobaric chamber. After hypoxic exposure for 2, 4, 12 weeks, one group of normal control and hypoxia model rats were killed and blood was collected, respectively. Then parameters of erythrocyte and blood rheology were examined. RESULTS: Mucous membrane of hypoxia model rats showed obviously cyanosis after 2 weeks hypoxic exposure. Hemoglobin concentration of hypoxia model rats were beyond 210 g/L after 2 weeks, 4 weeks and 12 weeks hypoxia exposure and significantly increased than that of normal control rats respectively. Besides, RBC counts, hematocrit, whole blood viscosity, erythrocyte aggregation index of hypoxia model rats were all notably higher than those of normal control rats respectively. CONCLUSION: A rat model of high altitude polycythemia can be rapidly established by hypobaric hypoxia exposure at simulated 5 500 m high altitude for 8 hours daily.