腺苷对大鼠视交叉上核c-fos蛋白表达的影响

目的观察腺苷对大鼠视交叉上核（SCN）内c-fos蛋白表达的影响,探讨腺苷对睡眠—觉醒活动的影响。方法将大鼠随机分成四组,分别向腹腔内注射腺苷3.0 g/L（腺苷组）、生理盐水3.0 g/L（对照1组）、腺苷3.0 g/L＋茶碱6.0 g/L（腺苷加茶碱组）、生理盐水6.0 g/L（对组2组）。采用常规石蜡切片技术和Fos免疫组织化学染色ABC法检测各组视交叉上核c-fos蛋白的表达。结果腺苷组视交叉上核内c-fos蛋白表达较对照1组明显升高（P〈0.01）;腺苷＋茶碱组较对照2组亦明显升高（P〈0.01）。结论腺苷可通过刺激视交叉上核内c-fos蛋白表达促进睡眠。     

腺苷对大鼠视交叉上核神经元自发放电的影响

目的观察腺苷对大鼠视交叉上核（SCN）神经元自发放电的影响,探讨腺苷对睡眠—觉醒活动的影响。方法采用离体脑片灌流和胞外神经元记录的方法,观察腺苷对大鼠SCN神经元自发放电的影响。结果腺苷对SCN的自发神经元放电以增加为主。结论腺苷能够增加SCN神经元自发放电,可能与SCN神经元上腺苷A2受体结合有关。     

模拟失重对大鼠肠黏膜NF-κB表达的影响

目的:探讨模拟失重条件下健康大鼠肠道黏膜组织中核因子-κB(NF-κB)的表达变化及其意义.方法:成年Wistar大鼠807,,随机分为10组,按模拟失重时相分别为0.5、1、2、7、21 d和相应的对照组.采用尾悬吊法建立模拟失重动物模型.免疫组织化学法检测肠道黏膜组织中NF-κB的表达水平.结果:0.5、1、2、7、21 d模拟失重组大鼠肠道组织NF-κB表达水平均显著高于相应对照组(10.11%±3.29%vs 5.50%±1.92%,22.00%±5.31%vs 6.50%±2.32%,25.50%±4.11%vs8.75%±6.36%,21.50%±3.02%vs 6.75%±2.12%,10.87%±2.64%vs 5.62%±2.13%,均P＜0.01),模拟失重0.5 d组肠道组织NF-κB表达开始升高,2 d组达高峰,随模拟失重时间的延长,NF-κB表达水平依次下降,21 d组仍然高于相应对照组.结论:尾悬吊模拟失重大鼠肠道组织NF-κB表达水平明显上调,提示肠道组织NF-κB表达变化与失重应激反应和失重耐受有密切关系.     

模拟失重大鼠胰腺组织HSP70表达的变化

目的 研究模拟失重环境下大鼠胰腺组织HSP70表达的变化.方法 健康雄性Wistar 大鼠64只,采用尾悬吊法建立模拟失重动物模型.按完全随机法分为悬尾6、12 h及1、2、3、5、7d组和未悬尾对照组.应用免疫组化法、蛋白质印迹法和RT-PCR法检测各组大鼠胰腺组织HSP70蛋白和mRNA的表达.结果 免疫组化染色显示,对照组大鼠胰腺组织无HSP70蛋白表达,悬尾组大鼠胰腺组织均有HSP70蛋白表达,尤其是胰岛细胞的胞质和胞核在早期即深染.蛋白质印迹法结果显示,悬尾6、12 h及1、2d组大鼠胰腺组织HSP70蛋白持续高表达,分别为0.921±0.078、0.862±0.048、0.838±0.063、0.807±0.071,较对照组的0.693 ±0.055显著增加(P＜0.05);3、5、7d组的HSP70蛋白表达恢复到对照组水平.HSP70 mRNA表达在6h组即明显增加至0.881 ±0.013,然后逐渐回落,3d组降至0.694±0.027,5d组出现回升,达0.836±0.014,7d组又回落至0.674±0.013.结论 模拟失重使大鼠胰腺组织中HSP70蛋白和mRNA表达发生明显变化,早期过表达,后期恢复正常水平.     

模拟失重对大鼠心肌细胞凋亡的影响

目的:探讨模拟失重对体外培养的大鼠心肌细胞凋亡的影响。方法: 以原代培养的乳鼠心肌细胞为研究对象,以细胞回转器模拟失重效应,通过流式细胞检测技术观察模拟失重96 h对心肌细胞凋亡率的影响,进一步通过RT-PCR的方法,检测模拟失重96 h后,心肌细胞凋亡相关基因p53、bcl-2和caspase-3 mRNA表达的影响。结果: 模拟失重96 h可显著增高心肌细胞的凋亡率(P<0.05),与对照组相比,回转器模拟失重可显著增高促凋亡基因p53、caspase-3 mRNA的表达(P<0.05),而抑凋亡基因bcl-2 mRNA则表达显著减低(P<0.05)。结论: 回转器模拟失重96 h致心肌细胞凋亡表达增高,其可能机制是凋亡相关基因表达失衡有关。     

模拟失重大鼠肝组织中NF-κB的表达及意义

目的:研究模拟失重环境下大鼠肝脏组织中NF-κB的表达及意义.方法:成年♂ Wistar 大鼠84只,随机分为模拟失重组和对照组,每组又分别设1、2、3、4、5、6和7 d共7个时相点,每时相点模拟失重和同步对照各6只大鼠.采用尾悬吊法建立模拟失重动物模型.各组大鼠肝组织中NF-κB表达分别应用Western blot 和免疫组化PV-6001法进行检测.结果:在尾悬吊1-2 d期间,大鼠焦躁不安,饮食量减少,精神较差,活动减弱,2-3 d后有所适应,逐渐恢复稳定状态.模拟失重环境下大鼠肝脏NF-κB表达水平明显升高,1、2 d悬尾组大鼠肝组织中NF-κB表达率明显高于对照组(F=271.36,P＜0.01),其后,NF-κB表达水平呈明显下降趋势势(F=60.68,P＜0.05),5-7 d悬尾组NF-κB表达水平接近对照组,差异无统计学意义.NF-κB阳性产物主要见于实验大鼠肝细胞内,亦见于炎细胞及Kupffer 细胞内,可分为胞质型、核型、核浆型等三个类型,单独或混合存在.结论:模模拟失重使大鼠肝脏组织中NF-κB表达发生明显变化,提示在失重环境中肝脏NF-κB的早期高表达和逐渐恢复过程与失重应激反应及失重耐受有密切关系.     

模拟失重状态下大鼠抗肺炎链球菌感染能力的变化

目的 观察模拟航天失重状态下呼吸道感染肺炎链球菌后抗感染能力的变化,为航天医疗保障提供依据.方法 建立模拟失重状态下大鼠链球菌肺炎模型,将32只健康雄性清洁级Wistar大鼠按随机数字表法分为4组:悬吊注菌组(A组)、悬吊未注菌组(B组)、未悬吊注菌组(C组)及未悬吊未注菌组(D组),每组8只,采用国内外公认成熟的尾悬吊法(身体纵轴与水平面约成30°)模拟失重状态,悬吊第4天通过气管捕管法将0.4ml(细菌浓度约9.0×108 CFU/ml)的标准肺炎链球菌菌株(ATCC6303,血清型3型,美国菌种保藏中心保存)注入肺组织,建立肺炎链球菌感染模型,对照组同时注入同等量的无菌生理盐水,仅注入1次.悬吊7d后取材,测定血常规、C反应蛋白及CD4+/CD8+.观察肺组织(每组均取右肺上叶)的炎症反应,并测量实验前后动物体重的变化.结果 A组肺组织表面凹凸不平,呈颗粒样改变,光镜下可见较严重的肺淤血和小静脉、毛细血管充盈扩张,肺泡融合增多,肺泡间隔增厚及肺泡腔受压变形,B、C组也可见部分上述改变,但程度较轻.各组间白细胞总数未见明显差异(F=1.57,P=0.22);A组中性粒细胞数为(2.4±0.5)×109/L,B组为(2.0±0.3)×109/L,C组为(1.7±0.4)×109/L,均高于D组的(1.2±0.2)×109/L(u值分别为0、1.0和8.5,均P＜0.05),A组与C组比较,差异有统计学意义(u=9.0,P=0.02).中性粒细胞百分比A组为0.26±0.04,高于C组的0.19±0.05(u =8.5,P=0.01);B组为0.23±0.03,C组为0.19±0.05,均高于D组的0.15±0.02(u值分别为2.0和13.0,均P＜0.05),而B组和C组比较差异无统计学意义(u=20.0,P=0.21);各组淋巴细胞总数比较差异无统计学意义(F=0.72,P=0.55),但A组[(6.0±0.9)×109/L]低于D组[(6.3±0.6) ×109/L];淋巴细胞百分比A组为0.66±0.08,B组为0.68±0.05,均低于D组的0.79±0.02 (F=10.24,P＜0.001).A组C反应蛋白为(11.9±2.2) g/L,明显高于D组的(1.5±0.8)g/L (u =0,P =0.001);4组CD4+/CD8+比值无明显差别(F=1.23,P=0.32);与其他组比较,A组体重减轻最明显,差异有统计学意义(F=122.07,P＜0.001).结论 失重状态下大鼠机体免疫功能降低,抗肺炎链球菌感染能力降低,肺部炎症反应更强,体重减轻更明显,需要给予相应的保障措施.     

模拟失重可通过BKCa信号调控大鼠肠系膜小动脉血管功能的昼夜节律变化

目的 探讨模拟失重对大鼠肠系膜小动脉舒张功能昼夜节律的影响以及血管舒张调控分子大电导钙激活钾离子（BK_Ca）信号的时间节律特征。 方法 采用1周尾部悬吊大鼠模型,检测大鼠肠系膜小动脉的舒张功能,继而在一天24 h内不同的6个授时因子时间点（Zeitgeber time,ZT)（ZT 0、4、8、12、16和20）以膜片钳电生理学方法记录BK_Ca通道的全细胞电流,以Western blot分析和RT-PCR检测BK_Ca通道a亚基的蛋白和mRNA表达水平。 结果 对照组大鼠肠系膜小动脉的舒张功能表现为白天升高（ZT4,中午12:00）、夜晚（ZT16,凌晨12:00）降低的趋势;而悬吊组大鼠后肠系膜小动脉舒张功能在白天与夜晚均显著下降（P < 0.05）,且其昼夜波动幅度明显降低（P < 0.05）。对照组大鼠肠系膜小动脉血管平滑肌细胞BK_Ca通道电流密度、a亚基的蛋白与mRNA表达水平均呈现“昼高夜低”的节律特征;而悬吊组可显著降低BK_Ca通道在白天与夜晚的电流密度、a亚基的蛋白与mRNA表达水平,而且其通道活性和蛋白表达的昼夜波动幅度也显著降低（均P < 0.05）,但mRNA表达水平的昼夜波动幅度没有明显变化,提示存在转录后修饰调控。 结论 模拟失重可通过BK_Ca信号调控大鼠肠系膜小动脉血管的昼夜节律变化,深入研究BK_Ca通道昼夜节律特征,对揭示航天飞行后心血管功能失调和血管疾病的发生机制均有深远的意义。     

模拟失重对大鼠动脉血胃动素和一氧化氮的影响

背景:随着载人航天事业的迅速发展,对失重状态下身体各器官系统变化的研究越来越受到重视。目前,关于失重状态下胃肠激素变化的研究尚少。目的:研究模拟失重状态下大鼠动脉血中胃动素和一氧化氮的变化,初步探讨两者在失重状态下胃肠功能调控中的可能作用。方法:90只雄性Wistar大鼠随机分为三组,每组各30只。第一组悬吊14 d(SUS-14 d组),第二组悬吊21 d(SUS-21 d组),第三组(对照组)不予悬吊。腹主动脉采血,测定动脉血胃动素(放射免疫法)和一氧化氮(硝酸还原酶法)水平。结果:模拟失重状态下(SUS-14 d组和SUS-21 d组),大鼠动脉血胃动素水平较对照组明显升高,差异有统计学意义(P0.05);一氧化氮水平与对照组相比差异无统计学意义(P0.05)。结论:模拟失重状态下,大鼠动脉血胃动素水平明显升高,一氧化氮水平变化不明显。胃动素水平的变化可能与失重状态下发生的胃肠功能改变有关,其具体机制有待进一步研究。     

Natural selection against a circadian clock gene mutation in mice

Circadian rhythms with an endogenous period close to or equal to the natural light–dark cycle are considered evolutionarily adaptive (“circadian resonance hypothesis”). Despite remarkable insight into the molecular mechanisms driving circadian cycles, this hypothesis has not been tested under natural conditions for any eukaryotic organism. We tested this hypothesis in mice bearing a short-period mutation in the enzyme casein kinase 1ε (tau mutation), which accelerates free-running circadian cycles. We compared daily activity (feeding) rhythms, survivorship, and reproduction in six replicate populations in outdoor experimental enclosures, established with wild-type, heterozygous, and homozygous mice in a Mendelian ratio. In the release cohort, survival was reduced in the homozygote mutant mice, revealing strong selection against short-period genotypes. Over the course of 14 mo, the relative frequency of the tau allele dropped from initial parity to 20%. Adult survival and recruitment of juveniles into the population contributed approximately equally to the selection for wild-type alleles. The expression of activity during daytime varied throughout the experiment and was significantly increased by the tau mutation. The strong selection against the short-period tau allele observed here contrasts with earlier studies showing absence of selection against a Period 2 (Per2) mutation, which disrupts internal clock function, but does not change period length. These findings are consistent with, and predicted by the theory that resonance of the circadian system plays an important role in individual fitness.Circadian clocks are a ubiquitous feature of life on earth, and serve to maintain synchrony of internal physiology with the external 24-h environment. Colin Pittendrigh, one of the founders of chronobiology, hypothesized that natural selection should favor circadian systems to operate in resonance with the external cycle (1, 2). A prediction from this hypothesis is that individuals exhibiting circadian rhythms with frequencies that are not in close resonance with the 24-h cycle should be selected against in nature. The hypothesis was initially supported by laboratory experiments in fly species that lived longer in a 24-h light–dark (LD) cycle than in non-24-h LD cycles (2–4). Stronger support emerged from dyadic competition experiments in batch cultures of cyanobacteria carrying single gene mutations affecting their circadian period (τ). Strains (either wild type or mutant) with a τ similar to the external LD cycle outcompeted strains with a τ different from the Zeitgeber (5, 6). Whether periods out of resonance with the external cycle entail a real fitness deficit in a natural setting has not been tested in any of these systems.The Ck1ε^tau (hereafter defined as the tau mutation) is a gain-of-function mutation (7) that accelerates the cellular dynamics of the circadian PERIOD protein (8, 9) and affects circadian behavior and physiology (10). It was first detected in Syrian hamsters (Mesocricetus auratus), where it causes τ to shorten with ∼2 h for each copy of the mutant allele (11). In mice, the same mutation shortens the circadian cycle to an almost identical extent (10). As a consequence of the accelerated circadian clockwork, both homozygote tau mice and hamsters are unable to entrain to 24-h LD cycles in the laboratory. Because its frequency deviates considerably from the natural 24-h cycle, the tau mutation provides an excellent model to study effects of deviant circadian periods on fitness in a natural setting. Here we report the consequences of deviant circadian rhythms in six replicate outdoor populations of mice. These populations were established with the release of mice, all born to two heterozygote parents, in identical enclosures, with ∼49% mutant tau alleles in a near Mendelian ratio in each pen. We used s.c. transponders to record each individual’s visits to feeders in each enclosure, which allowed us to quantify the rhythm of feeding activity and to keep track of each individual’s presence—and, hence, monitor lifespan, mortality, and the tau allele frequency in each population.     

The circadian clock controls the expression pattern of the circadian input photoreceptor, phytochrome B

Developmental and physiological responses are regulated by light throughout the entire life cycle of higher plants. To sense changes in the light environment, plants have developed various photoreceptors, including the red/far-red light-absorbing phytochromes and blue light-absorbing cryptochromes. A wide variety of physiological responses, including most light responses, also are modulated by circadian rhythms that are generated by an endogenous oscillator, the circadian clock. To provide information on local time, circadian clocks are synchronized and entrained by environmental time cues, of which light is among the most important. Light-driven entrainment of the Arabidopsis circadian clock has been shown to be mediated by phytochrome A (phyA), phytochrome B (phyB), and cryptochromes 1 and 2, thus affirming the roles of these photoreceptors as input regulators to the plant circadian clock. Here we show that the expression of PHYB::LUC reporter genes containing the promoter and 5' untranslated region of the tobacco NtPHYB1 or Arabidopsis AtPHYB genes fused to the luciferase (LUC) gene exhibit robust circadian oscillations in transgenic plants. We demonstrate that the abundance of PHYB RNA retains this circadian regulation and use a PHYB::Luc fusion protein to show that the rate of PHYB synthesis is also rhythmic. The abundance of bulk PHYB protein, however, exhibits only weak circadian rhythmicity, if any. These data suggest that photoreceptor gene expression patterns may be significant in the daily regulation of plant physiology and indicate an unexpectedly intimate relationship between the components of the input pathway and the putative circadian clock mechanism in higher plants.