Huiping Ma

Introduction: Cognitive impairment is a common symptom for these people entering high altitude. Unfortunately, the potential molecular mechanisms are not totally clear. This study aimed to identify the genes and signaling pathways associated with high-altitude cognitive dysfunction (HACD) in mice. Methods: Male C57BL/6 J mice were allocated into two groups: control group and hypobaric hypoxia (HH) group. The cognitive function was assessed using novel object recognition test and Morris water maze test. The histological analysis was performed using Hematoxylin-Eosin (HE) staining and Nissl staining. Evans blue (EB) assay was performed to evaluate the integrity of the blood-brain barrier (BBB). The gene levels in hippocampal tissue were assessed via RNA-Seq technique. Differentially expressed genes (DEGs) were identified using the DESeq2 R package, followed by functional and pathway enrichment analyses. The protein-protein interaction (PPI) network was established for screening hub genes, which were subsequently validated by qRT-PCR. The related proteins were detected by Western blot. Results: HH exposure led to pathological changes in hippocampal tissue, accompanied by increased oxidative stress, inflammatory response, and BBB disruption, and then induced impaired cognitive function in mice. In the HACD mice, 178 DEGs (70 upregulated and 108 downregulated genes) were found, in comparison to the control, and 8 hub genes were identified. GO and KEGG enrichment analysis demonstrated that PI3K/AKT signaling pathway is a significantly enriched pathway, suggesting its potential involvement in the pathogenesis of HACD. Then, we performed validation experiments via qRT-PCR for four hub genes ( Vwf , Vegfa , Kdr , Spp1 ) closely related to the PI3K/AKT signaling pathway, and the results aligned with the RNA-seq data. Furthermore, Western blot analysis indicated that the PI3K/AKT pathway was substantially inhibited following HH exposure. Downstream analysis revealed significantly decreased expression of antioxidant proteins Nrf2 and HO-1, accompanied by increased phosphorylation of NF-κB, indicating enhanced neuroinflammation and impaired antioxidant defenses. Conclusions: Our results reveal a significant association between PI3K/AKT signaling pathway inhibition and HACD and offer potential therapeutic targets for developing novel treatment strategies for HACD.

Background: High-altitude pulmonary edema (HAPE) is a severe and potentially fatal complication without effective and safe measures. 7-hydroxyethyl chrysin (7-HEC) is a derivative of chrysin and exhibits excellent anti-hypoxia activities. The objective of this study was to investigate the protective effect and mechanism of 7-HEC against HAPE. Methods: The HAPE rat model was established using a hypobaric hypoxic cabin. The lung water content (LWC) and pulmonary microvascular permeability were measured, and the pathological changes of lung tissue were assessed by HE staining. The arterial blood gas indexes and routine blood indexes were measured. The levels of oxidative stress, inflammatory, energy metabolism and endothelial function markers in lung tissue or serum were quantified by commercial kits. qRT-PCR and Western blotting were employed to analyze the expressions of inflammatory and permeability associated genes and proteins. Network pharmacology and molecular docking were performed to reveal the pivotal targets of 7-HEC against HAPE and underlying mechanisms. Results: 7-HEC treatment reduced the LWC, attenuated pulmonary microvascular hyperpermeability, and improved lung tissue pathology in HAPE rats. Moreover, 7-HEC treatment normalized HAPE-induced changes in arterial blood gas and routine blood parameters. In addition, 7-HEC treatment significantly inhibited oxidative stress and inflammation, suppressed the energy metabolism dysfunction, and maintained the endothelial function. PI3K/AKT signaling pathway was identified as the core pathway for 7-HEC against HAPE by the results of network pharmacology analysis, molecular docking and Western blotting. Furthermore, LY294002, a selective PI3K/AKT inhibitor, significantly attenuated the protective effects of 7-HEC against HAPE. Conclusion: These findings indicate that 7-HEC may mitigate HAPE by activating the PI3K/AKT signaling pathway and could serve as an effective agent for preventing HAPE.

Purpose: Our Prior research has shown that 6-hydroxygenistein (6-OHG) alleviates hypobaric hypoxia induced brain injury (HHBI) achieved by its powerful antioxidant, anti-inflammatory, and anti-apoptotic capabilities, but its mechanism still requires additional investigation. The objective of this study was to uncover the protective mechanism of 6-OHG against HHBI based on transcriptomics analysis and experimental validation. Methods: The gene levels in brain tissue obtained from previous study were accessed via the RNA-Seq technique. DESeq2 R package was used to identify the differentially expressed genes (DEGs). Functional enrichment analysis and molecular docking were investigated utilizing the clusterProfiler R package and Autodock Vina software, respectively. In experimental validation stage, histological analysis was performed using Hematoxylin-Eosin (HE) staining. Oxidative stress, inflammatory, and apoptotic indexes in brain tissue were measured using commercial kits. Western blot was applied for detecting related protein expression. Results: The RNA-Seq analysis revealed 905 differentially expressed genes (DEGs) between the Con and Mod groups, with 239 upregulated and 666 downregulated. Between the 6-OHG and Mod groups, there were 192 DEGs, including 98 upregulated and 94 downregulated genes. Go and KEGG function analyses highlighted the PI3K/AKT signaling pathway as a crucial regulatory mechanism. Western blot analysis showed that HH exposure caused a decrease in the ratios of p-PI3K/PI3K and p-AKT/AKT in the mouse brain, but this effect was reversed by 6-OHG treatment, indicating that 6-OHG activates the PI3K/AKT signaling pathway. Furthermore, LY294002, a selective PI3K inhibitor, effectively blocked this activation and also abolished the protective effects of 6-OHG on histopathological damage, as well as its antioxidant, anti-inflammatory, and anti-apoptotic activities in HHBI mice. Conclusion: 6-OHG mitigates HHBI by activating the PI3K/AKT signaling pathway, suggesting its potential therapeutic application for HHBI treatment.

Oxidative stress has been considered to be closely related to spaceflight‐induced bone loss; however, mechanism is elusive and there are no effective countermeasures. Using cultured rat calvarial osteoblasts exposed to microgravity simulated by a random positioning machine, this study addressed the hypotheses that microgravity‐induced shortening of primary cilia leads to oxidative stress and that primary cilium protection prevents oxidative stress and osteogenesis loss. Microgravity was found to induce oxidative stress (as represented by increased levels of reactive oxygen species (ROS) and malondialdehyde production, and decreased activities of antioxidant enzymes), which was perfectly replicated in osteoblasts growing in NG with abrogated primary cilia (created by transfection of an interfering RNA), suggesting the possibility that shortening of primary cilia leads to oxidative stress. Oxidative stress was accompanied by mitochondrial dysfunction (represented by increased mitochondrial ROS and decreased mitochondrial membrane potential) and intracellular Ca²⁺ overload, and the latter was found to be caused by increased activity of Ca²⁺ channel transient receptor potential vanilloid 4 (TRPV4), as also evidenced by TRPV4 agonist GSK1016790A‐elicited Ca²⁺ influx. Supplementation of HC‐067047, a specific antagonist of TRPV4, attenuated microgravity‐induced mitochondrial dysfunction, oxidative stress, and osteogenesis loss. Although TRPV4 was found localized in primary cilia and expressed at low levels in NG, microgravity‐induced shortening of primary cilia led to increased TRPV4 levels and Ca²⁺ influx. When primary cilia were protected by miR‐129‐3p overexpression or supplementation with a natural flavonoid moslosooflavone, microgravity‐induced increased TRPV4 expression, mitochondrial dysfunction, oxidative stress, and osteogenesis loss were all prevented. Our data revealed a new mechanism that primary cilia function as a controller for TRPV4 expression. Microgravity‐induced injury on primary cilia leads to increased expression and overactive channel of TRPV4, causing intracellular Ca²⁺ overload and oxidative stress, and primary cilium protection could be an effective countermeasure against microgravity‐induced oxidative stress and loss of osteogenic potential of osteoblasts.

Pulsed electromagnetic fields (PEMFs) have long been recognized being safe and effective in treating bone fracture nonunion and osteoporosis. However, the mechanism of osteogenic action of PEMFs is still unclear. While primary cilia are reported to be a sensory organelle for PEMFs, and nitric oxide (NO) plays an indispensable role in osteogenic effect of PEMFs, the relationship between NO and primary cilia is unknown. In this study, effects of treatment with 50 Hz 0.6 mT PEMFs on osteogenic differentiation and mineralization, NO secretion, and ciliary location of specific proteins were examined in rat calvarial osteoblasts (ROBs) with normal or abrogated primary cilia. It was found that PEMFs stimulated the osteogenic differentiation by activating the NOS/NO/sGC/cGMP/PKG signaling pathway, which need the existence of primary cilia. All components of the signaling pathway including iNOS, eNOS, sGC, PKG‐1, and PKG‐2 were localized to primary cilia, and eNOS was phosphorylated inside the primary cilia. Besides, primary cilia were elongated significantly by PEMF treatment and changed dynamically with the activation NO/cGMP pathway. When the pathway was blocked by L‐NAME, PEMFs could no longer elongate the primary cilia and stimulate the osteoblastic differentiation. Thus, this study for the first time observed activation of the NO/cGMP signaling pathway in ciliary compartment of osteoblasts, and PEMFs could not stimulate the osteoblastic differentiation if the NO signaling pathway was blocked or the ciliogenesis was inhibited. Our findings indicate the interdependent relationship between NO and primary cilia in the PEMF‐promoted osteogenesis.

Severe oxidative stress triggered by acute hypobaric hypoxia (AHH) is harmful for lots of organs in body, especial brain and heart. Flavonoids with antioxidant properties can protect organs from oxidative stress. Our previous study found that 5,6,7,8-trtrahydroxyflavone (5,6,7,8-THF), a flavones with four consecutive hydrogen group on ring A, showed excellent antioxidant properties in vitro. In the present study, the protective of 5,6,7,8-THF against oxidative stress caused by AHH was investigated. Mice were administered with 5,6,7,8-THF(500mg/kg) for 5 consecutive days before HH exposure. The heart rate (HR) and blood pressure (BP) was measured. The activity of SOD, CAT, GSH-Px, LDH, Na+-K+-ATPase and Ca2+-Mg2+-ATPase and the content of H2O2, MDA, LD and ATP in brain and heart tissue was evaluated using commercial kit. AHH led to a significant increase in HR and decrease in BP. Pretreatment of 5,6,7,8THF could reversed these changes. In addition, administration of 5,6,7,8-THF could significantly increase the activity of SOD, CAT and GSH-Px and decrease the content of H2O2 and MDA in the brain and heart of mice under AHH. Furthermore, 5,6,7,8-THF inhibited the activity of LDH, decreased the level of LD and improved ATPase activity. These results indicate that 5,6,7,8-THF may protect the mice against AHH injury via scavenging free radical, inhibiting lipid peroxidation, enhancing antioxidant enzyme activity, preserving energy metabolism and can be further explored as an excellent anti-hypoxia agent for preventing acute mountain sickness.

Background: Norwogonin is a natural flavone with three phenolic hydroxyl groups in skeletal structure and has excellent antioxidant activity. However, the neuroprotective effect of norwogonin remains unclear. Here, we investigated the protective capacity of norwogonin against oxidative damage elicited by hypoxia in PC12 cells. Methods: The cell viability and apoptosis were examined by MTT assay and Annexin V-FITC/PI staining, respectively. Reactive oxygen species (ROS) content was measured using DCFH-DA assay. Lactate dehydrogenase (LDH), malondialdehyde (MDA) and antioxidant enzyme levels were determined using commercial kits. The expression of related genes and proteins was measured by real-time quantitative PCR and Western blotting, respectively. Results: We found that norwogonin alleviated hypoxia-induced injury in PC12 cells by increasing the cell viability, reducing LDH release, and ameliorating the changes of cell morphology. Norwogonin also acted as an antioxidant by scavenging ROS, reducing MDA production, maintaining the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), and decreasing the expression levels of HIF-1α and VEGF. In addition, norwogonin prevented cell apoptosis via inhibiting the expression levels of caspase-3, cytochrome c and Bax, while increasing the expression levels of Bcl-2 and the ratio of Bcl-2/Bax. Conclusions: Norwogonin attenuates hypoxia-induced injury in PC12 cells by quenching ROS, maintaining the activities of antioxidant enzymes, and inhibiting mitochondrial apoptosis pathway.