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@#[Objective] To investigate the evolution of inflammation under conditions and the effects of ginsenosides on macrophages subjected to the simulated weightlessness, with the aim of mitigating the inflammation. [Methods] Initially, genes related to weightlessness, inflammation, and immunity were identified in the GeneCards database. Then, Search Tool for the Retrieval of Interaction Gene/Proteins (STRING) protein network analysis was conducted to determine the core targets involved in the weightlessness-induced inflammation. Subsequently, Label-Free Quantitative (LFQ) proteomics was carried out to discern the distinctive genes within ginsenoside-treated Tohoku Hospital Pediatrics-1 (THP-1) cells. Next, utilizing the outcomes of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, the biological processes and signaling pathways in which ginsenosides predominately engaged were scrutinized, and the primary targets of ginsenosides in combating weightlessness-induced inflammation were examined. Finally, enzyme-linked immunosorbent assay (ELISA) was performed to detect the secretion levels of interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α from lipopolysaccharide (LPS)-induced THP-1 cells under simulated weightlessness conditions, as well as during the weightlessness recovery period following treatment with ginsenosides. [Results] A total of 2 933 genes associated with inflammation, 425 genes linked to weightlessness, and 4 564 genes connected to immunity were retrieved from the GeneCards database. Protein-protein interaction (PPI) networks were generated to identify pivotal targets associated with weightlessness-induced inflammation such as IL-1β, IL-6, TNF, and albumin (ALB). It was found that ginsenosides primarily participated in the regulation of various inflammationrelated signaling pathways and pathways related to pathogenic microorganism infections. Moreover, it has a significant impact on the expression of proteins such as cluster of differentiation 40 (CD40), IL-1β, and poly ADP-ribose polymerase 1 (PARP1). As revealed in the simulated weightlessness cell test, ginsenosides exhibited a remarkable capacity to attenuate the secretion of inflammatory factors, specifically IL-6 and TNF-α (P < 0.000 1), in THP-1 macrophages following induction by LPS under simulated weightlessness conditions. In addition, it reduced the secretion of IL-1β, IL-6, IL-8, and TNF-α (P < 0.000 1) during the weightlessness recovery phase [Conclusion] Weightlessness can disrupt several inflammation-related signaling pathways, but ginsenosides were shown to mitigate the release of various inflammatory factors in macrophages subjected to simulated weightlessness, thereby exerting a protective role against inflammation. This study has laid a theoretical groundwork for further exploring the potential application of ginsenosides in safeguarding against LPS induced inflammation in a weightlessness environment.
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OBJECTIVE Microgravity exerts several negative effects on the learning and memory of astro-nauts during space flight.Rg1 and Rb1,the key steroidal components of ginseng,have shown potent neuroprotec-tive effects with a high safety profile.The object of the current study is to investigate the influence of Rg1 and Rb1 on simulated microgravity-induced memory and learning dysfunction in the hindlimb suspension(HLS)rat model.METHODS The HLS rats were orally administered Rg1(30 and 60 μmol·kg-1)or Rb1(30 and 60 μmol·kg-1)for four weeks.The Morris water maze test(MWM)and reward operating conditioning reflex test(ROCR)were conducted to evaluate spatial and associative learning and memory.After the behavior tests,the serum and the prefrontal cortex(PFC)were dissected to measure the mechanism.RESULTS Rg1 and Rb1 treatment amelio-rated the cognitive deficits of HLS-exposure rats in MWM and ROCR,reduced reactive oxygen species generation and increased antioxidant enzyme activity.Rg1 and Rb1 also assisted in the recovery of mitochondrial complex Ⅰ(NADH dehydrogenase)activities and Mfn2,and decrea-sed Drp-1 expression.Furthermore,Rg1 and Rb1 reduced the ratio of Bax/Bcl-2 and the expression of cleaved-cas-pase 3,cytochrome c,increased the levels of SYN,PSD95 and activated BDNF-TrkB/PI3K-Akt pathway in the PFC.CONCLUSION Rg1 and Rb1 treatment attenuated cog-nitive deficits induced by HLS,mitigated mitochondrial dysfunction,attenuated oxidative stress,inhibited apopto-sis,and increased the synaptic plasticity,which was partly mediated by the modulation of the BDNF-TrkB/PI3K-Akt signaling.
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Objective@#To explore the therapeutic effects of ginseng total saponins (GTSs) on cognitive impairments in astronauts caused by prolonged exposure to microgravity environment.@*Methods@#Fifty specific pathogen-free (SPF) male Wistar rats were randomized into control, hindlimb suspension (HLS), Huperzine A (HLS-Hup A 0.1 mg/kg), low-dose GTSs (HLS-GTSs 100 mg/kg), and high-dose GTSs (HLS-GTSs 200 mg/kg) groups, based on the completion time of reward-directed conditioning tasks. Except for rats in the control group, the others were subjected to HLS and treated with drugs (day 20 – 58), received reflex test under the condition of rewarding, and underwent Nissl body staining and Western blot detection on hippocampal.@*Results@#After modeling, rats in HLS group exhibited a reduction in the number of lever presses and an increase in the completion time of the reward-directed operant conditioning task Ⅰ (P < 0.05) when compared with the control group, which were not substantially altered in the HLS-GTSs 100 and 200 mg/kg groups (P > 0.05). In the reward-directed operant conditioning task Ⅱ, the HLS group rats demonstrated a marked decrease in the number of lever presses (P < 0.05) and nose pokes (P < 0.01) when compared with the control group rats; the HLS-GTSs 100 mg/kg showed a significant increase in the number of lever presses and nose pokes (P < 0.05), while the HLS-GTSs 200 mg/kg demonstrated a significant reduction in completion time and an elevation in the number of lever presses (P < 0.05) when compared with the HLS group rats. In visual signal discrimination task, compared with the control group rats, the HLS group rats showed decrease in the indexes of the visual signal discrimination(P < 0.01), while HLS-GTSs 100 and 200 mg/kg groups exhibited manifest increase in it (P < 0.01). In reward extinction experiment, the number of lever presses in HLS rats significantly increased when compared with the control group (P < 0.01); compared with the HLS group, HLS-GTSs 100 and 200 mg/kg groups demonstrated a marked descrease (P < 0.05). The expressions of N-methyl-D-aspartic acid receptor 1 (NR1) and phosophorylated N-methyl-Daspartic acid receptor 2B (p-NR2B) proteins were markedly decreased in rats in the HLS group (P < 0.05 and P < 0.01, respectively), while that of NR2B protein maintained the same (P > 0.05). GTSs increased the expression levels of p-NR2B (P < 0.01).@*Conclusion@#GTSs improved the learning and memory ability of complex operations by regulating the NR1/NR2B phosphorylation pathways in rats.
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Objective:To investigate the effect of total ginsenoside ginseng root on the learning and memory impairment and anxiety of hindlimb suspension rats by detecting the performance of rats in the water maze， elevated plus maze， and the expression of hypothalamic-pituitary-adrenal （HPA） axis， inflammatory factors and tryptophan pathway related factors through the intervention of ginsenosides in hindlimb suspension rats. Method:The Wistar male rats were divided into normal group， hindlimb suspension model group， Huperzine A group （0.1 mg·kg<sup>-1</sup>）， and total ginsenoside ginseng root low and high dose groups （100， 200 mg·kg<sup>-1</sup>）， with 8 rats in each group. Except for the normal group， the rats in the other groups maintained a -30° hindlimb suspension state for 24 h. The normal group and the model group received intragastric administration of 10 mL·kg<sup>-1</sup> pure water . After 28 days of continuous administration， the water maze and elevated plus maze behavioral tests were performed. After the tests， blood was taken from the abdominal aorta， and the rat brain cortex was peeled off on ice， quenched with liquid nitrogen， and stored at -80 ℃ for later use. LC-MS/MS was used to detect neurotransmitter levels of dopamine， acetylcholine， glutamate， <italic>γ</italic>-aminobutyric acid and tryptophan pathway metabolites （tryptophan， 5-hydroxytryptamine， 5-hydroxyindoleacetic acid， kynurenine， 3-hydroxykynurenine， and kynurenine） in rat brain cortex. An enzyme-linked immunosorbent assay （ELISA） kit was used to detect the levels of inflammatory factors interleukin-6 （IL-6）， interleukin-10 （IL-10， the HPA axis-related hormone corticotropin （ACTH）， and the level of corticosterone （CORT）. Result:Compared with the normal group， the escape latency in the water maze significantly increased， the number of crossings was significantly reduced， and the number of open-arm entry and the percentage of open-arm entry were significantly reduced in the elevated plus maze in model group （<italic>P</italic><0.05，<italic> P</italic><0.01）， the content of dopamine， acetylcholine， glutamic acid， and <italic>γ</italic>-aminobutyric acid in the cortex decreased， kynurenine and kynurenic acid showed an upward trend， 3-hydroxykynurenine， 5-hydroxytryptamine， 5-hydroxyindole acetic acid showed a downward trend， and the levels of IL-6， IL-10， ACTH， and CORT in the serum significantly increased （<italic>P</italic><0.05， <italic>P</italic><0.01）. Compared with the model group of rats， total ginsenoside ginseng root low and high dose groups group reduced the avoidance latency in the water maze， and increased the number of crossings and the number of open arms of the elevated plus maze， dopamine， acetylcholine， glutamate， and <italic>γ</italic>-aminobutyl content increased， while kynurenine and kynurenic acid showed a downward trend， 3-hydroxykynurenine， serotonin， and 5-hydroxyindole acetic acid showed an upward trend， and IL-6， IL-10， ACTH， and CORT factor levels were down-regulated（<italic>P</italic><0.05， <italic>P</italic><0.01）. Conclusion:Hindlimb suspension for 28 days in simulated microgravity can impair the learning and memory ability of rats and cause anxiety-like behaviors. Total ginsenoside ginseng root can improve their learning and memory impairment and anxiety-like behaviors. The mechanism may be mainly related to inhibiting body inflammation and regulating HPA axis imbalance.
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The Chinese space station will be built around 2020. As a national space laboratory, it will offer unique opportunities for studying the physiological effects of weightlessness and the efficacy of the countermeasures against such effects. In this paper, we described the development of countermeasure systems in the Chinese space program. To emphasize the need of the Chinese space program to implement its own program for developing countermeasures, we reviewed the literature on the negative physiological effects of weightlessness, the challenges of completing missions, the development of countermeasure devices, the establishment of countermeasure programs, and the efficacy of the countermeasure techniques in American and Russian manned spaceflights. In addition, a brief overview was provided on the Chinese research and development on countermeasures to discuss the current status and goals of the development of countermeasures against physiological problems associated with weightlessness.
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Humans , China , Program Evaluation , Space Flight , Weightlessness , Weightlessness SimulationABSTRACT
Objective To observe the effect of simulated microgravity on the photopic negative response (PhNR) of full-field flash ERG in adult mice.Methods In an experimental study,forty-eight adult male C57BL/6J mice (48 eyes) were randomly divided into model and control groups.Model mice were further divided into three subgroups of 8 each:tail-suspended for 15 days (subgroup A),tail-suspended for 30 days (subgroup B),and tail-suspended for 30 days followed by returning to normal position for 30 days (subgroup C).The three control subgroups were similarly fixed with a harness but kept in the normal position for corresponding periods of 15,30,and 60 days.The mice were immediately examined using ERG-PhNR,flash VEP,OCT and visually-guided behavior in vivo,and subsequently sacrificed to analyze the retinal histology in vitro.PhNR amplitude was measured from baseline to PhNR trough.N1 peak-time and N1-P1 amplitude of VEP was analyzed.The escape duration was used to quantitatively evaluate the visual function of mice.In addition,inner retinal thickness was analyzed by OCT imaging.Data were compared by the independent sample t-test.Results PhNR amplitude in the model subgroup A was obviously lower than the corresponding control subgroup,the difference was statistically significant (t=-3.196,P＜0.01).There was no significant difference in PhNR amplitude between the model subgroup B or C and the corresponding control subgroup (t=-1.976,0.285;P＞0.05).There was no significant difference in FVEP N1 peak-time or N1-P1 amplitude between any of the three model subgroups and the corresponding control subgroup (P＞0.05).There was no significant difference in OCT-measured inner retinal thickness between any of the three model subgroups and the corresponding control subgroup (t=-0.461,2.073,-0.402;P＞0.05).The three model subgroups showed almost normal retinal structure,including the retinal ganglion cell,inner pexiform layer,inner nuclear layer,outer plexiform layer,outer nuclear layer,ellipsoid zone and RPE.There was no significant difference in visually-guided escape time between any of the three model subgroups and the corresponding control subgroup (t=-0.637,-0.955,1.297;P＞0.05).Conclusion Via tail-suspension,short-term simulated microgravity can affect the PhNR of flash ERG;however,the change is reversible and does not affect visual function of mice.
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As an effective physical training method to improve the explosive power of athletes, plyometric training(exercise) has made great contributions to the physical training of Chinese Olympic Teams.However,the way this method is used for astronaut onboard training and the maintenance of human body strength is not yet clear enough.There is no training program or system of astronaut onboard training currently available that uses this training method in China.Based on the analysis of related researches at home and abroad, this paper comprehensively and systematically expounds the principles of plyometric training and research related to athletic performance.The view that this method is used for astronaut onboard training is also proposed innovatively in this paper.The aim of this study is to expand the field of physical training for astronauts and provide reference for the training of weightlessness protection in the field of aerospace in China.
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Objective:To investigate the changes of gene or protein expression and activity of matrix metalloprotein9 (MMP9) and tissue inhibitor ofmetalloproteinasel (TIMP1) in the carotid artery (CA) of 4 wk hindlimb unweighted rat.Methods:A 4 weeks(wk) hindlimb unweighted (HU) rat model was used to simulate the effect of weightlessness on the cardiovascular system.Transmission electron microscopy was used to detect the content of ECM.Reverse transcriptase polymerase chain reaction(RT-PCR) was conducted to measure the mRNA content MMP and TIMP1.Immunohistochemistry and Western blot technique were used to measure the protein abundance.Gelatin zymography was carried out to detect the activity of MMP9.Results:Compared to the control group (CON),the area of ECM was enhanced (P＜0.05) and the content of collage fiber was increased (P＜0.05) in the CA of HU rats;moreover,HU did not affect the mRNA expression of MMP9,but significantly reduced the protein content (P＜0.05) or enzymatic activity (P＜0.05).Accordingly,the mRNA or protein expression of TIMP1 in the CA was significantly increased by HU (P＜0.05).Conclusion:Simulated weightlessness caused imbalance between MMP and TIMP1 expression,which might contribute to the ECM aggregation and stiffness of CA.
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Objective: To observe the morphological changes on cochlear hair cells of rats in simulated weightlessness and inboard noise and to investigate the different changes in three turns of hair cells.Methods: Thirty-two healthy SD rats, all males, were randomly divided into four groups: control group, weightlessness group, noise group and weightlessness+noise groups (n=8).Then rats were exposed to-30° head down tilt as simulated weightlessness and inboard noise including steady-state noise which was (72±2) dB SPL and impulse noise up to 160 dB SPL in spaceship environment.The control group was kept in normal condition for 8 weeks.Bilateral auditory brainstem response (ABR) thresholds were tested before and after exposure respectively, and immunofluorescence staining and scanning electron microscopy (SEMs) of basilar membrane were applied after exposure.Results: ABR threshold shifts of each group were higher after exposure.There was difference between ABRs of the experiment groups before and after exposure (Pnoise group>weightlessness group>control group and the damage degree of the four turns of hair cells: basal turn>mid turn>top turn.Conclusion: The rats exposed to the above environment for 2 weeks displayed obvious changes in cochlea morphology, and the weightlessness+noise group had the most obvious damage.
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Objective To investigate the effects of simulated microgravity by rotary cell culture system (RCCS) on expression profiles of miRNA in mouse fibroblasts L929 cell line.Methods L929 cells were cultured in vitro and divided into simulated microgravity (SMG) group and normal gravity (NG) group according to the simple random method.Samples of two groups were collected on 7th day of culture and the total RNAs were extracted,labeled,and hybridized in sequence.Feature Extraction Software was used to collect the array images and get raw data,which were analyzed by Genespring Software.Differentially expressed miRNAs were identified and then validated by qRT-PCR.Target genes of differentially expressed miRNAs were predicted by the databases of Targetscan and microRNAorg,and the intersections of databases were identified as potential regulatory target genes.Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) analysis were applied to determine the roles of these target genes.Relevant biological functions and/or signaling pathways of the regulated genes especially related with wound healing process were categorized based on their enrichments.Then integration predictions of the miRNA and mRNA expression profiles had been proposed to refine the functional miRNA-mRNA relationships.The miRNA-mRNA functional network and miRNA-mRNA control network were constructed.Results Four miRNA genes were up-regulated significantly including mmumiR-669j,-122-5p,-30a-3p,-6516-3p,among which mmu-miR-669j was up-regulated at 52.84 folds with the greatest significance (P ＜ 0.05).Seventeen miRNA genes were down-regulated significantly including mmu-miR-21a-3p,-miR-28a-5p,-218-5p,-210-3p,-miR-19a-3p,-miR-31-3p,and-miR-19b-3p,among which mmu-miR-28a-5p was down-regulated at 15.47 folds with the greatest significance (P ＜ 0.05).The qRT-PCR showed a high concordance with the microarray results (P ＜ 0.05).Target gene prediction and functional enrichment analysis suggested that a variety of biological processes and signaling pathways involved in wound repair were significantly enriched (P ＜ 0.05).Function network and regulation network of miRNA-mRNA covered all the differentially expressed miRNAs,which suggested that miR-21 a-3p and predicted target gene Smad3 might play an important role in wound healing under microgravity.Conclusions Simulated microgravity by RCCS can significantly affect the expression of stress-related miRNAs in mouse fibroblasts L929.The miRNA target gene prediction and functional enrichment analysis based on gene chip technology may provide theoretical basis for illustrating the mechanism and management of weightlessness stress injury.
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OBJECTIVE To investigate the effects of simulated noise-weightlessness combined factors on auditory brainstem response thresholds and the cochlear structure after a medium-long term (2-8 weeks). METHODS Healthy adult rats were randomly divided into male/female experimental and control groups. The male and female experimental groups were exposed to simulated noise-weightlessness environment and exerted impulse noise exposure at the end. Auditory brainstem response (ABR) threshold was recorded at the beginning, the 2nd, 4th and 8th weeks and after impulse noise exposure exerting. The cochlea was also examined by scanning electron microscopy each time after ABR threshold record. RESULTS ABR thresholds in experimental groups after impulse noise exposure were significantly increased (P<0.05). Female experimental group were lower than those of the male experimental group at 2 and 4 weeks (P<0.05). Scanning electron microscope observation showed that the inner and outer hair cell were losing and lodging, and the longer exposed to the compound factors, the heavier pathological changes observed on the cochlear hair cell. CONCLUSION Noise-weightlessness combined factors can cause the morphology and function damage of rat cochlear in medium-long term. The damage of impulse noise was more than steady noise on rat auditory function. Sex differences was also observed. Rat cochlear hair cell pathological changes increased with the exposed time.
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Objective To observe the different characteristics of spontaneous activitiy after simulated weightlessness 21 days in rats , aimed to provide a evaluation method for space weightlessness induced function change in human beings and to provide a reference for researches on the astronauts protective measures .Methods 30 Wistar male rats were randomly divided into three groups , the control group , the sham tail-suspended hindlimb unloading group ( the sham group ) , the tail-suspended hindlimb unloading group ( the suspending group ) , ten animals in each group .All animals were placed in the simulated space flight environmental equipment which has a real -time monitor system for 21 days.During the 21 days, the intake of water , food and the body weight were measured every week .Meanwhile, five independent activity data were collect every day , for example, morning(8:00am~12:00am), afternoon(2:00pm~6:00pm), daytime(8:00am~8:00pm),night(8:00pm~8:00am),and whole day (8:00am ~8:00am).Results The spontaneous activity of normal rats in the control group between morning and afternoon had no significant difference , but it is significantly between night and daytime .The movement time and distance in night are 2 -3 times than that of the daytime.After 10 days of tail suspending , the circadian rhythm was disordered , and the spontaneous activity in day and night become more similar in rats of the suspending group .Because of the individual difference , the spontaneous activity is not stable at the first 10 days in rats of the sham group , but after 10 days, it become close to the control group .Conclusion Rat is nocturnal animal and sleeps in the daytime , the spontaneous activity in night is 2 -3 times as compared with the daytime.The sham tail-suspended hindlimb unloading 21 days can not influence the circadian rhythm in rats .Tail suspending 21 days will caused to the disappearance in the circadian rhythm in rats .
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Objective To investigate the effect of simulated microgravity on growth , morphology, protein expression and virulence gene expression of Klebsiella pneumoniae (KPN).Methods KPN was divided into simulated microgravity group and control group in the experiment .The former group was in the ambient of simulated microgravity in a clinostat .The bacterial growth curves , morphologyical changes in electron microscopy , and protein expression were detected by SELDI-TOF-MS, and the expression of 4 virulence genes(ureA,wabG,uge and fimH) by real-time fluorescence quantitative PCR (RT-PCR) in both groups.Results Compared with the control group , the growth of KPN under simulated microgravity was accelerated , and the total bacterial count increased in microgravity group .The bacterial morphology in microgravity group was changed under scanning electron microscopy (SEM), and thinner and longer bacteria were increased .The transmission electron microscopy ( TEM) analysis revealed increase in cytoplasmic granular substance in microgravity group .Proteome analysis showed that the expression of 18 proteins was changed , half of which up-regulated and the rest were down-regula-ted.Those 18 proteins were searched in the protein library .And 21 proteins of a similar molecular mass were retrieved ,13 of which,proteins with known functions ,were closely related to bacterial life activities .RT-PCR results showed that four virulence genes of KPN were down-regulated.Conclusion Upon exposure to simulated microgravity , the growth and repro-duction of KPN are accelerated and enhanced .The bacterial morphology is changed .The strain′s protein expression and four virulence genes expressionare also changed .Therefore,microgravity can change the characteristics of KPN .
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Objective To investigate the effects of simulated null gravity on the secretion of adrenomedullary hormones and miRNA-375 expression in rats. Method Fifty-six healthy adult male Wistar rats were randomly divided into 7 experimental groups (8 each), including suspension for 6h, 12h, 1d, 3d, 5d, 7d and 0h (control). Tail-suspension was used to establish the weightlessness animal model according to Morey-Holton's method. At the end of the experiment, the blood samples were obtained from the postorbitor vein, and the bilateral adrenal glands were harvested. The serum concentrations of catecholamines were determined by radioimmunological analysis. The expression of TH mRNA and miRNA-375 were assessed by quantitative RTPCR. TH protein in adrenal medulla was assayed using Western blotting analysis and immunohistochemistry. Results(1) The serum concentrations of rat's adrenomedullary hormones fluctuated obviously during the period of tail-suspension simulated weightlessness, with a temporary decline during 6-12h, followed by a sharp increase with a peak value on the 3rd day of suspension. (2) RT-PCR assay showed that TH mRNA expression in adrenal medulla of rats also fluctuated obviously, with a temporary decline at 6h and then elevated with a peak value at 1 day of suspension, followed by a downward trend forming a trough value on 5d of suspension. The immunohistochemistry showed that TH protein was stained as brown particles and the cytoplasm of adrenal medulla was stained deeply on 3d of suspension. (3) RT-PCR assay revealed that the expression of miRNA-375 in adrenal medulla increased temporarily at 6h of suspension, and it decreased significantly during 12h to 3d of suspension compared with that of control group (P<0.05). The miRNA-375 expression was up-regulated again during sustained suspension with a significant increase on 7d of experiment compared with that of control group (P<0.05). Conclusion The simulated weightlessness could affect the secretion of hormone of adrenal medulla in rats, and it may be related to the regulation of TH through miRNA-375 messenger network.
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With the development of business of manned spaceflight, the body damage of astronauts on the space en-vironment has received growing concern. Weight loss is the most important cause of various diseases, and the weightlessness muscle atrophy is one of urgent problems to be solved in aerospace medicine. Although there is no concept of weightlessness or weightlessness muscle atrophy in the theory of traditional Chinese medicine (TCM), TCM can grasp the pathogenesis of complex diseases, and provide important theoretical references for the prevention and management of weightlessness diseases, especially weightlessness muscle atrophy. In this paper, TCM Cognition of weightlessness and the pathogenesis of weightlessness muscle atrophy was studied by the sight of TCM theory of qi hoisting. The discussion was made from aspects of circulation of qi and blood, zang-fu function. This work is wished to be beneficial to apply the TCM theory in aerospace medicine.
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BACKGROUND: Weightlessness is one of the important reasons to cause lower limb muscle atrophy of the astronauts, which is serious harm to the health of astronauts. OBJECTIVE: To explore the progress of weightlessness that cause lower limb muscle atrophy. METHODS: A computer-based online search of PubMed database and CNKI database was performed to search related articles between May 1981 and March 2013 with the key words of “weightless, weightlessness, muscle, atrophy, space” in English and Chinese, respectively. Literatures related to progress of weightlessness that cause lower limb muscle atrophy were selected; in the same field, the literatures published lately in authoritative journals were preferred. RESULTS AND CONCLUSION: A total of 409 literatures were primarily selected, and 47 documents were involved for summary according to the inclusion criteria. The progress of weightlessness that cause muscle atrophy is the hot topic among the space medical research. The main reasons that cause weightlessness muscular atrophy include the reduced muscle spindle neurotrophic factor synthesis caused by reduced information transmission of peripheral sensory nerve, damage of muscle cel ultrastructure, substantial decline in mitochondrial myofibrils, troponin decreasing, decreased intracel ular calcium content, and decreased antigravity muscle blood flow in lower limbs.
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Objective To study the effects of compound factors of simulated weightlessness and noise in spaceship on auditory function ,and the expression of apoptotic marker Caspase -3 in inner ear in guinea pigs ,and study the influence of compound factor above on its hearing loss and apoptosis of inner ear .Methods Thirty -six guinea pigs were randomly divided into four groups ,6 in control group ,10 in simulated weightlessness with noise group (Group A) ,treatment estrogen group (Group B) and prevention estrogen (Group C) ,respectively .All the experiment groups were suspended posterior limb ,with the exposure of the simulated noise circumstance in space-ship .Estrogen prevention group received intramuscular injection of estradiol benzoate for 3 days before the experiment ,while estrogen treatment group was treated in the same way for 8 days from the beginning of experiment to 3 days after the experiment .Bilateral auditory brainstem response thresholds (ABR) were tested in pre- exposure ,post-exposure and 3 -day recovery respectively .Cochleae were obtoined for immunohistochemistry staining to observe the expression of the apoptotic marker Caspase -3 in inner ear .Results At the time point of post -exposure ,ABR threshold in Group B was lower than those in Group A by 14 .5 dB and Group C by 9 dB .For the ABR change of pre ,and post-exposure ,Group B was lower 12 .75 dB than those of in Group A and 7 .75 dB than in Group C .For the ABR change between pre ,and post-recovery ,ABR threshold of Group C was higher than those of in Group A by 14 .5 dB and in Group B by 7 dB .These differences were significant (P<0 .05) .The expression of Caspase-3 was positive in the hair cell ,spiral ganglion cells and stria vascularis of three groups in both post exposure and 3-day recovery .The expression of Caspase-3 in hair cell and stria vascularis was strongly positive in spiral ganglion cells in Group C in post -exposure ,while it was slightly positive in Group B .After 3 -day recovery ,Group A turned to negative ,while Group B and Group C were still in positive expression with an increase of that in post -ex-posure .Conclusion Estrogen treatment could effectively reduce the hearing loss and the apoptosis of inner ear in-duced by the compound factor of weightlessness and noise .Preventive use of estrogen could not produce an instant protection on the hearing loss induced by exposure ,and the apoptosis was enhanced .However ,it speeded up the procedure of recovery and reduced the apoptosis of inner ear .
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Microgravity is one of the important environmental conditions during spaceflight. A series of studies have shown that many kinds of bacteria could be detected in space station and space shuttle. Space environment or simulated microgravity may throw a certain influence on those opportunistic pathogens and lead to some changes on their virulence, biofilm formation and drug tolerance. The mechanism of bacteria response to space environment or simulated microgravity has not been defined. However, the conserved RNA-binding protein Hfq has been identified as a likely global regulator involved in the bacteria response to this environment. In addition, microgravity effects on bacterial pathogenicity may threaten astronauts' health. The present paper will focus on microgravity-induced alterations of pathogenicity and relative mechanism in various opportunistic pathogens.
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Objective To explore the effect of weightlessness simulation on processing speed of mental rotation of males in 72 h head-down tilt,in order to further reveal human performance changes caused by weightlessness.Methods During 72 h weightlessness simulation (9 am day 1 to 9 pm day 4,head-down tilt started from 9 pm day 1),16 male subjects were processed speed of rotation data byhand picture mental rotation (test 8 times),using self cross-references design,and the variation of processing speed of mental rotation by duration was analyzed.Results The linear regression analysis showed,the reaction time of each time point for each subject as the independent variable,the angle of rotation as the dependent variable,with the extension of simulated weightlessness time.The intercept(constant term of the regression equation),indicating the processing speed of non-rotation,were gradually increased with HDT time,but didn(t) reached significantly difference (F(3,14) =0.551,P =0.650) ;the slope(Regression coefficient of the regression equation),indicating the processing speed of rotation.were gradually increased with HDT time,and reached the significantly difference (F(3,14) =4.338,P =0.009).The value of intercept and slope was like upside-down U in three days,and reached the highest value at day 2.Conclusion Weightlessness simulation have affection on the speed of mental rotation,especially on the rotation speed.
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Microgravity environment is a stress and extracellular signal that affects cellular morphology and function through signal transduction system, thus leading to certain biological effect. At present, many signaling pathways have been reported to be involved in the regulation of cell function under microgravity environment, such as NF-κB signaling pathway, Notch signaling pathway, MAPK signaling pathway, HSP signaling pathway and so on, and these reports have laid a foundation for the molecular studies of cytolergy under outer space environment. The recent progress in the researches on intracellular signaling pathways affected by microgravity is herewith reviewed in present paper in the hope of providing references for understanding the cell activity in space environment, and to find the ways to alleviate the harmful effects caused by the microgravity environment.