[Intermittent hypoxic preconditioning relieves fear and anxiety behavior in post-traumatic stress model mice].

Intermittent hypoxia (IH) has preventive and therapeutic effects on hypertension, myocardial infarction, cerebral ischemia and depression, but its effect on post-traumatic stress disorder (PTSD) has not been known. In this study, we used inescapable electric foot shock combined with context recapture to build PTSD mouse model. The levels of fear and anxiety were valued by the open field, the elevated plus maze (EPM) and the fear conditioning tests; the level of spatial memory was valued by Y maze test; the number of Fos positive neurons in hippocampus, amygdala and medial prefrontal cortex was valued by immunohistochemical staining; and the protein expressions of hypoxia inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF) and brain derived neurotrophic factor (BDNF) in these brain area were valued by Western blot. The results showed that IH and model (foot shock) had an interaction on percentage of entering open arms (OE%) in EPM and freezing time and the number of fecal pellets in fear conditioning test. IH increased OE% in EPM and reduced the freezing time and the number of fecal pellets in fear conditioning test in PTSD model mice. At the same time, IH reduced the number of Fos positive neurons in the hippocampus, amygdala and medial prefrontal cortex of PTSD model mice, and increased the protein expression levels of HIF-1α, VEGF and BDNF in these brain tissues. In conclusion, IH pretreatment can relieve fear and anxiety behavior in post-traumatic stress model mice, suggesting that IH may be an effective means of preventing PTSD.

WIP1 phosphatase is a critical regulator of adipogenesis through dephosphorylating PPARγ serine 112.

WIP1, as a critical phosphatase, plays many important roles in various physiological and pathological processes through dephosphorylating different substrate proteins. However, the functions of WIP1 in adipogenesis and fat accumulation are not clear. Here, we report that WIP1-deficient mice show impaired body weight growth, dramatically decreased fat mass, and significantly reduced triglyceride and leptin levels in circulation. This dysregulation of adipose development caused by the deletion of WIP1 occurs as early as adipogenesis. In contrast, lentivirus-mediated WIP1 phosphatase overexpression significantly increases the adipogenesis of pre-adipocytes via an enzymatic activity-dependent mechanism. PPARγ is a master gene of adipogenesis, and the phosphorylation of PPARγ at serine 112 strongly inhibits adipogenesis; however, very little is known about the negative regulation of this phosphorylation. Here, we show that WIP1 phosphatase plays a pro-adipogenic role by interacting directly with PPARγ and dephosphorylating p-PPARγ S112 in vitro and in vivo.

miR-210 protects renal cell against hypoxia-induced apoptosis by targeting HIF-1 alpha.

The kidney is vulnerable to hypoxia-induced injury. One of the mechanisms underlying this phenomenon is cell apoptosis triggered by hypoxia-inducible factor-1-alpha (HIF-1α) activation. MicroRNA-210 (miR-210) is known to be induced by HIF-1α and can regulate various pathological processes, but its role in hypoxic kidney injury remains unclear. Here, in both kinds of rat systemic hypoxia and local kidney hypoxia models, we found miR-210 levels were upregulated significantly in injured kidney, especially in renal tubular cells. A similar increase was observed in hypoxia-treated human renal tubular HK-2 cells. We also verified that miR-210 can directly suppress HIF-1α expression by targeting the 3' untranslated region (UTR) of HIF-1α mRNA in HK-2 cells in severe hypoxia. Accordingly, miR-210 overexpression caused significant inhibition of the HIF-1α pathway and attenuated apoptosis caused by hypoxia, while miR-210 knockdown exerted the opposite effect. Taken together, our findings verify that miR-210 is involved in the molecular response in hypoxic kidney lesions in vivo and attenuates hypoxia-induced renal tubular cell apoptosis by targeting HIF-1α directly and suppressing HIF-1α pathway activation in vitro.

Hypoxia augments LPS-induced inflammation and triggers high altitude cerebral edema in mice.

High altitude cerebral edema (HACE) is a life-threatening illness that develops during the rapid ascent to high altitudes, but its underlying mechanisms remain unclear. Growing evidence has implicated inflammation in the susceptibility to and development of brain edema. In the present study, we investigated the inflammatory response and its roles in HACE in mice following high altitude hypoxic injury. We report that acute hypobaric hypoxia induced a slight inflammatory response or brain edema within 24h in mice. However, the lipopolysaccharide (LPS)-induced systemic inflammatory response rapidly aggravated brain edema upon acute hypobaric hypoxia exposure by disrupting blood-brain barrier integrity and activating microglia, increasing water permeability via the accumulation of aquaporin-4 (AQP4), and eventually leading to impaired cognitive and motor function. These findings demonstrate that hypoxia augments LPS-induced inflammation and induces the occurrence and development of cerebral edema in mice at high altitude. Here, we provide new information on the impact of systemic inflammation on the susceptibility to and outcomes of HACE.

Dissolved oxygen concentration in the medium during cell culture: Defects and improvements.

In vitro cell culture has provided a useful model to study the effects of oxygen on cellular behavior. However, it remains unknown whether the in vitro operations themselves affect the medium oxygen levels and the living states of cells. In addition, a prevailing controversy is whether reactive oxygen species (ROS) production is induced by continuous hypoxia or reoxygenation. In this study, we have measured the effects of different types of cell culture containers and the oxygen environment where medium replacement takes place on the actual oxygen tension in the medium. We found that the deviations of oxygen concentrations in the medium are much greater in 25-cm(2) flasks than in 24-well plates and 35-mm dishes. The dissolved oxygen concentrations in the medium were increased after medium replacement in normoxia, but remained unchanged in glove boxes in which the oxygen tension remained at a low level (11.4, 5.7, and 0.5% O2 ). We also found that medium replacement in normoxia increased the number of ROS-positive cells and reduced the cell viability; meanwhile, medium replacement in a glove box did not produce the above effects. Therefore, we conclude that the use of 25-cm(2) flasks should be avoided and demonstrate that continuous hypoxia does not produce ROS, whereas the reoxygenation that occurs during the harvesting of cells leads to ROS and induces cell death.

Methylene Blue Reduces Acute Cerebral Ischemic Injury via the Induction of Mitophagy.

The treatment of stroke is limited by a short therapeutic window and a lack of effective clinical drugs. Methylene blue (MB) has been used in laboratories and clinics since the 1890s. Few studies have reported the neuroprotective role of MB in cerebral ischemia-reperfusion injury. However, whether and how MB protects against acute cerebral ischemia (ACI) injury was unclear. In this study, we investigated the effect of MB on this injury and revealed that MB protected against ACI injury by augmenting mitophagy. Using a rat middle cerebral artery occlusion (MCAO) model, we demonstrated that MB improved neurological function and reduced the infarct volume and necrosis after ACI injury. These improvements depended on the effect of MB on mitochondrial structure and function. ACI caused the disorder and disintegration of mitochondrial structure, while MB ameliorated the destruction of mitochondria. In addition, mitophagy was inhibited at 24 h after stroke and MB augmented mitophagy. In an oxygen-glucose deprivation (OGD) model in vitro, we further revealed that the elevation of mitochondrial membrane potential (MMP) by MB under OGD conditions mediated the augmented mitophagy. In contrast, exacerbating the decline of MMP during OGD abolished the MB-induced activation of mitophagy. Taken together, MB promotes mitophagy by maintaining the MMP at a relatively high level, which contributes to a decrease in necrosis and an improvement in neurological function, thereby protecting against ACI injury.

Enhanced hypoxia-inducible factor (HIF)-1α stability induced by 5-hydroxymethyl-2-furfural (5-HMF) contributes to protection against hypoxia.

We first reported the role of 5-hydroxymethyl-2-furfural (5-HMF) against hypoxia. Here, we studied the mechanism by using oxygen-dependent degradation domain (ODD)-Luc mice, which are a useful model to probe the stabilization of hypoxia-inducible factor 1α (HIF-1α). Compared with three other compounds that have been reported to have a role in stabilizing HIF-1α, 5-HMF caused stronger bioluminescence, which is indicative of HIF-1α stability in the brain and kidney of ODD-Luc mice. We further demonstrated that the HIF-1α protein accumulated in response to 5-HMF in the brains and kidneys of these mice, as well as in PC12 cells. Additionally, 5-HMF promoted the nuclear translocation of HIF-1α and the transcriptional activity of HIF-1, which was evaluated by detecting vascular endothelial growth factor (VEGF ) mRNA expression. These results suggest that 5-HMF stabilized HIF-1α and increased its activity. Considering the role of proline hydroxylases (PHDs) in negatively regulating HIF-1α stability, we explored whether 5-HMF interacts with the substrates and cofactors of PHDs, such as 2-oxoglutarate (2-OG), Fe(2+) and vitamin C (VC), which affects the activity of PHDs. The result revealed that 5-HMF did not interact with Fe(2+) or 2-OG but interacted with VC. This interaction was confirmed by subsequent experiments, in which 5-HMF entered into cells and reduced the VC content. The enhanced stability of HIF-1α by 5-HMF was reversed by VC supplementation, and the improved survival of mice caused by 5-HMF under hypoxia was abrogated by VC supplementation. Thus, we demonstrated for the first time that 5-HMF increases HIF-1α stability by reducing the VC content, which mediates the protection against hypoxia.

Notch1 mediates postnatal neurogenesis in hippocampus enhanced by intermittent hypoxia.

Notch1 is a transcription factor on the membrane and regulates various stages of neurogenesis. Recently, studies have shown that in vitro neurogenesis is enhanced by hypoxia, and there is cross-coupling between Notch and hypoxia signaling pathways in vitro. However, to date, no data have reported whether Notch1 can be regulated by hypoxia in vivo and mediates hypoxia-induced neurogenesis. To determine causative links between Notch1, neurogenesis and hypoxia, we examined multiple steps of hippocampal neurogenesis followed intermittent hypoxia (IH) in wild type (WT) and Notch1 heterozygous deficient (N+/-) mice. We found that IH increased NSC proliferation, newborn neuron survival and migration, and spine morphogenesis in dentate gyrus of hippocampus, as well as neurogenesis in olfactory bulb in WT mice. However, IH-enhanced neurogenesis was inhibited in N+/- mice. It was shown that Notch1 signaling was activated following IH in WT mice, but not in N+/- mice. Our data indicated that IH, as a novel external stimulus, enhances neurogenesis at multiple stages and that Notch1 is activated by hypoxia in vivo and required for hypoxia-induced neurogenesis. These results suggest IH as a novel therapeutic strategy for degenerative neurological disorders and provide evidence for causative links between Notch1, neurogenesis and hypoxia.

FHL family members suppress vascular endothelial growth factor expression through blockade of dimerization of HIF1α and HIF1ß.

Four and a half LIM domain (FHL) proteins belong to a family of LIM-only proteins that have been implicated in the development and progression of various types of cancers. However, the role of FHL proteins in tumor angiogenesis remains to be elucidated. Herein, we demonstrate that FHL1-3 decrease the promoter activity and expression of vascular endothelial growth factor (VEGF), the key regulator of angiogenesis in cancer growth and progression as well as an important target gene of the transcription factor hypoxia-inducible factor 1 (HIF1α/HIF1ß). FHL1-3 interacted with HIF1α both in vitro and in vivo. A single LIM domain of FHL1 was sufficient for its interaction with HIF1α. FHL1 interacted with the HIF1α region containing basic helix-loop-helix (bHLH) motif and PER-ARNT-SIM domain, both of which aid in dimerization with HIF1ß and DNA binding. FHL1-3 inhibited HIF1 transcriptional activity and HIF1-mediated VEGF expression in a hypoxia-independent manner. Moreover, FHL1 blocked HIF1α-HIF1ß heterodimerization and HIF1α recruitment to the VEGF promoter. These data suggest that FHL proteins are involved in negative regulation of VEGF possibly by interfering with the dimerization and DNA binding of HIF1 subunits and may play an important role in tumor angiogenesis.

CHL1 negatively regulates the proliferation and neuronal differentiation of neural progenitor cells through activation of the ERK1/2 MAPK pathway.

Neural recognition molecules of the immunoglobulin superfamily play important roles in the development and regeneration of nervous system. Close Homologue of L1 (CHL1) is a member of the L1 family of recognition molecules which are expressed during neuronal development, suggesting a potential role in neural progenitor cells (NPCs). Here, we investigated the role of CHL1 in the proliferation and differentiation of NPCs both in vivo and in vitro, and the possible mechanism involved. The number of BrdU-positive cells in the subventricular zone (SVZ) significantly increased in CHL1-/- mice compared with CHL1+/+ mice. Moreover, there were more Tuj1-positive cells in the cortical plate region in CHL1-/- mice than in CHL1+/+ controls. To further examine the function of CHL1 in the proliferation and differentiation of NPCs, NPCs from CHL1-/- mice versus littermate wild-type mice were isolated and cultured in vitro. NPCs derived from CHL1-/- mice showed increased proliferation and self-renewal ability compared with CHL1+/+ mice. In the course of differentiation, CHL1 deficiency enhanced neuronal differentiation in the absence of growth factors. Furthermore, CHL1 deficiency on the proliferation of NPCs is accompanied by means of enhanced activation of ERK1/2 mitogen-activated protein kinase (MAPK) and the inhibitor of ERK1/2 MAPK eliminates the effect of CHL1 deficiency on the proliferation of NPCs. Our results first describe the negative modulation of the proliferation and neuronal differentiation of NPCs by CHL1/ERK1/2 MAPK signaling.

Loss of NB-3 aggravates cerebral ischemia by impairing neuron survival and neurite growth.

BACKGROUND AND PURPOSE: NB-3 is a member of the F3/contactin family of neural recognition molecules, which are crucial for cell morphogenesis and motility. NB-3 is expressed in neurons and plays an important role in axonal extension and neuronal survival. However, the role of NB-3 in cerebral ischemic injury remains unknown. METHODS: Adult male wild-type and NB-3 knockout mice were subjected to ischemic injury by unilateral middle cerebral carotid artery occlusion for 3 hours, 6 hours, and 12 hours. Ischemic infarction volumes were then determined by 2, 3, 5-triphenyltetrazolium chloride staining. Neurological dysfunction analysis was also performed. Primary culture of neuronal cells from wild-type and knockout animals was also used for analysis of neuronal survival and neurite outgrowth. RESULTS: NB-3 expression in the ischemic hemisphere was decreased after transient middle cerebral artery occlusion (MCAO). NB-3-knockout mice developed a 2.6-fold larger infarct volume and exhibited increased neurological deficit scores after transient middle cerebral artery occlusion compared with control mice. Substrate with NB-3 promoted neuronal survival and neurite outgrowth in vitro, whereas neurite outgrowth and neuronal survival were significantly reduced in NB-3-deficient neurons. In addition, NB-3 deficiency renders neurons more susceptible to oxygen-glucose deprivation-induced damage and NB-3 as substrate could partially through homophilic mechanisms. CONCLUSIONS: These data demonstrate that NB-3 deficiency may aggravate brain damage after middle cerebral artery occlusion by impairing neuronal survival and neurite growth.

Small ncRNA expression and regulation under hypoxia in neural progenitor cells.

Small non-coding RNA (ncRNA) plays critical roles in a large number of cellular processes, including neural development, cell survival and cell determination. Our previous work showed that low oxygen promoted the survival and proliferation of neural progenitor cells (NPCs) in vitro. In this study, we examine the expression and regulation of small ncRNAs in the hypoxia-driven proliferation of NPCs. The expression profiles of ncRNAs in NPCs under hypoxia were detected using microarray analysis. Results of significance analysis of microarrays (SAM) revealed that 15 small RNAs were up-regulated at least threefold and 11 were down-regulated under hypoxic conditions. The differentially expressed small ncRNAs were confirmed by quantitative RT-PCR, and miR-210 was observed to be highly expressed in NPCs under hypoxic conditions. Further study showed that hypoxia-inducible factor (HIF)-1α had a direct impact on the putative promoter regions of miR-210. From these results, we conclude that some small ncRNAs participate in the regulation of the proliferation of NPCs under hypoxia and that miR-210 is directly regulated by HIF-1α.

Telocytes accompanying cardiomyocyte in primary culture: two- and three-dimensional culture environment.

Recently, the presence of telocytes was demonstrated in human and mammalian tissues and organs (digestive and extra-digestive organs, genitourinary organs, heart, placenta, lungs, pleura, striated muscle). Noteworthy, telocytes seem to play a significant role in the normal function and regeneration of myocardium. By cultures of telocytes in two- and three-dimensional environment we aimed to study the typical morphological features as well as functionality of telocytes, which will provide important support to understand their in vivo roles. Neonatal rat cardiomyocytes were isolated and cultured as seeding cells in vitro in two-dimensional environment. Furthermore, engineered myocardium tissue was constructed from isolated cells in three-dimensional collagen/Matrigel scaffolds. The identification of telocytes was performed by using histological and immunohistochemical methods. The results showed that typical telocytes are distributed among cardiomyocytes, connecting them by long telopodes. Telocytes have a typical fusiform cell body with two or three long moniliform telopodes, as main characteristics. The vital methylene blue staining showed the existence of telocytes in primary culture. Immunohistochemistry demonstrated that some c-kit or CD34 immuno-positive cells in engineered heart tissue had the morphology of telocytes, with a typical fusiform cell body and long moniliform telopodes. Also, a significant number of vimentin+ telocytes were present within engineered heart tissue. We suggest that the model of three-dimensional engineered heart tissue could be useful for the ongoing research on the functional relationships of telocytes with cardiomyocytes. Because the heart has the necessary potential of changing the muscle and non-muscle cells during the lifetime, telocytes might play an active role in the heart regeneration process. Moreover, telocytes might be a useful tool for cardiac tissue engineering.

Efficient isolation of cardiac stem cells from brown adipose.

Cardiac stem cells represent a logical cell type to exploit in cardiac regeneration. The efficient harvest of cardiac stem cells from a suitable source would turn promising in cardiac stem cell therapy. Brown adipose was recently found to be a new source of cardiac stem cells, instrumental to myocardial regeneration. Unfortunately, an efficient method for the cell isolation is unavailable so far. In our study we have developed a new method for the efficient isolation of cardiac stem cells from brown adipose by combining different enzymes. Results showed that the total cell yield dramatically increased (more than 10 times, P < .01) compared with that by previous method. The content of CD133-positive cells (reported to differentiate into cardiomyocytes with a high frequency) was much higher than that in the previous report (22.43% versus 3.5%). Moreover, the isolated cells could be the efficiently differentiated into functional cardiomyocytes in optimized conditions. Thus, the new method we established would be of great use in further exploring cardiac stem cell therapy.

Close Homolog of L1 Deficiency Exacerbated Intestinal Epithelial Barrier Function in Mouse Model of Dextran Sulfate Sodium-Induced Colitis.

The cell adhesion molecule CHL1, which belongs to the immunoglobulin superfamily, functions in a variety of physiological and pathological processes, including neural development, tissue injury, and repair. We previously found that the loss of CHL1 exacerbated the dextran sulfate sodium (DSS)-induced colitis in mice. In the present study, we further addressed the role of CHL1 in mouse model of DSS-induced colitis and its' potential mechanism. Colon tissues were collected from CHL1+/+, CHL1+/-, and CHL1-/- mice after DSS induction to investigate the effects of CHL1 on the development of colitis. The data showed that CHL1 was expressed in intestine tissue, and expression of CHL1 was increased by DSS-induced inflammation. CHL1 deficiency induced more pronounced colitis features, exacerbated inflammation, and damage to colonic tissues in DSS-induced mice. Moreover, colonic tissues of CHL1-/- mice showed a marked increase in neutrophil and macrophage infiltration, be accompanied by more severe damage to intestinal epithelial cells and higher fluorescein isothiocyanate (FITC) leakage. Our results revealed deficiency of CHL1 exacerbated DSS-induced colitis, and this pathogenesis was potentially mediated by disruption of intestinal barrier integrity, indicating that CHL1 may be an attractive therapeutic target for inflammatory bowel diseases (IBDs) in mice.

[Effects of CHL1 deficiency,a cell adhesion molecule,on the inflammatory bowel disease].

OBJECTIVE: To investigate the effects of deficiency of CHL1 in inflammatory bowel disease (IBD). METHODS: Dextran Sulfate Sodium (DSS)-induced colitis model was used to study the effects of deficiency of CHL1 on the development of IBD. Ten CHL1(+/+) mice in C57/BL6 background were randomly divided into CHL1(+/+) group and DSS-induced CHL1(+/+) group. Ten CHL1(-/-) mice in C57/BL6 background were randomly divided into CHL1(-/-) group and DSS-induced CHL1(-/-) group. DSS-induced CHL1(+/+) group and DSS-induced CHL1(-/-)group were fed with 1.5% DSS for 7 days, and then drinking distilled water for 2 days. CHL1(+/+) group and CHL1(-/-) group as control group were fed with distilled water for 9 days. The changes of weight, survival, fecal blood and the change of colon length in this study were observed. RESULTS: On the 7th day, the weight of DSS-induced CHL1(-/-) group were reduced significantly, and DSS-induced CHL1(-/-) group had extreme mortality on the 9th day. The fecal blood of DSS-induced CHL1(-/-) group also had higher score than that of DSS-induced CHL1(+/+) group. In the DSS-induced CHL1(-/-) group,the length of colon was shortened obviously. CONCLUSIONS: The loss of CHL1 aggravates the development of IBD.

Ketogenic diet improves the spatial memory impairment caused by exposure to hypobaric hypoxia through increased acetylation of histones in rats.

Exposure to hypobaric hypoxia causes neuron cell damage, resulting in impaired cognitive function. Effective interventions to antagonize hypobaric hypoxia-induced memory impairment are in urgent need. Ketogenic diet (KD) has been successfully used to treat drug-resistant epilepsy and improves cognitive behaviors in epilepsy patients and other pathophysiological animal models. In the present study, we aimed to explore the potential beneficial effects of a KD on memory impairment caused by hypobaric hypoxia and the underlying possible mechanisms. We showed that the KD recipe used was ketogenic and increased plasma levels of ketone bodies, especially ß-hydroxybutyrate. The results of the behavior tests showed that the KD did not affect general locomotor activity but obviously promoted spatial learning. Moreover, the KD significantly improved the spatial memory impairment caused by hypobaric hypoxia (simulated altitude of 6000 m, 24 h). In addition, the improving-effect of KD was mimicked by intraperitoneal injection of BHB. The western blot and immunohistochemistry results showed that KD treatment not only increased the acetylated levels of histone H3 and histone H4 compared to that of the control group but also antagonized the decrease in the acetylated histone H3 and H4 when exposed to hypobaric hypoxia. Furthermore, KD-hypoxia treatment also promoted PKA/CREB activation and BDNF protein expression compared to the effects of hypoxia alone. These results demonstrated that KD is a promising strategy to improve spatial memory impairment caused by hypobaric hypoxia, in which increased modification of histone acetylation plays an important role.

WIP1 Phosphatase Plays a Critical Neuroprotective Role in Brain Injury Induced by High-Altitude Hypoxic Inflammation.

The hypobaric hypoxic environment in high-altitude areas often aggravates the severity of inflammation and induces brain injury as a consequence. However, the critical genes regulating this process remain largely unknown. The phosphatase wild-type p53-induced phosphatase 1 (WIP1) plays important roles in various physiological and pathological processes, including the regulation of inflammation in normoxia, but its functions in hypoxic inflammation-induced brain injury remain unclear. Here, we established a mouse model of this type of injury and found that WIP1 deficiency augmented the release of inflammatory cytokines in the peripheral circulation and brain tissue, increased the numbers of activated microglia/macrophages in the brain, aggravated cerebral histological lesions, and exacerbated the impairment of motor and cognitive abilities. Collectively, these results provide the first in vivo evidence that WIP1 is a critical neuroprotector against hypoxic inflammation-induced brain injury.

Intermittent hypoxia maintains glycemia in streptozotocin-induced diabetic rats.

Increasing studies have shown protective effects of intermittent hypoxia on brain injury and heart ischemia. However, the effect of intermittent hypoxia on blood glucose metabolism, especially in diabetic conditions, is rarely observed. The aim of this study was to investigate whether intermittent hypoxia influences blood glucose metabolism in type 1 diabetic rats. Streptozotocin-induced diabetic adult rats and age-matched control rats were treated with intermittent hypoxia (at an altitude of 3 km, 4 h per day for 3 weeks) or normoxia as control. Fasting blood glucose, body weight, plasma fructosamine, plasma insulin, homeostasis model assessment of insulin resistance (HOMA-IR), pancreas ß-cell mass, and hepatic and soleus glycogen were measured. Compared with diabetic rats before treatment, the level of fasting blood glucose in diabetic rats after normoxic treatment was increased (19.88 ± 5.69 mmol/L vs. 14.79 ± 5.84 mmol/L, p < 0.05), while it was not different in diabetic rats after hypoxic treatment (13.14 ± 5.77 mmol/L vs. 14.79 ± 5.84 mmol/L, p > 0.05). Meanwhile, fasting blood glucose in diabetic rats after hypoxic treatment was also lower than that in diabetic rats after normoxic treatment (13.14 ± 5.77 mmol/L vs. 19.88 ± 5.69 mmol/L, p<0.05). Plasma fructosamine in diabetic rats receiving intermittent hypoxia was significantly lower than that in diabetic rats receiving normoxia (1.28 ± 0.11 vs. 1.39 ± 0.11, p < 0.05), while there were no significant changes in body weight, plasma insulin and ß-cell mass. HOMA-IR in diabetic rats after hypoxic treatment was also lower compared with diabetic rats after normoxic treatment (3.48 ± 0.48 vs. 3.86 ± 0.42, p < 0.05). Moreover, intermittent hypoxia showed effect on the increase of soleus glycogen but not hepatic glycogen. We conclude that intermittent hypoxia maintains glycemia in streptozotocin-induced diabetic rats and its regulation on muscular glycogenesis may play a role in the underlying mechanism.

A method for establishing the high-altitude cerebral edema (HACE) model by acute hypobaric hypoxia in adult mice.

BACKGROUND: Exposure to acute hypobaric hypoxia (AHH) during ascent to high altitudes (>3500 m) is one of the main causes of acute mountain sickness (AMS) and high-altitude cerebral edema (HACE). Therefore, the aim of this study was to develop a model of HACE. NEW METHODS: We developed a model of HACE in mice using a decompression chamber with rapid ascent speed. RESULTS: Healthy male C57BL/6 mice were randomly divided into the control group and the AHH group. The AHH group was housed in a decompression chamber (at a velocity of 50 m/s within 5 min to 6000 m). Compared with the controls, brain water content was increased in the early stage (within 24 h) in the AHH group. After 72 h of exposure to AHH, there was a higher BBB permeability observed. In addition, the brain structure showed significant widening of the pericellular spaces and a dilatation of the cortical blood vessels after exposure to AHH, and some of the neurons appeared shrunken with darkly stained pyknotic nuclei, resulting in neuronal structural damage. Further, exposure to AHH also decreased cognitive function in the mice. COMPARISON WITH EXISTING METHODS: At present, there are no simple and rapid mouse models to study this syndrome in terms of its genetic basis, gene polymorphisms and susceptibility. CONCLUSION: Our findings show that AHH can increase BBB permeability and lead to cerebral edema in mice; thus, we provide an effective and stable model of HACE in mice.