亚热带平原绵羊的高温应激反应

对考湖杂种羊在夏季高温下的应激反应作了一些生理生化测试分析。环境温度逐渐增高时,绵羊的体温、心率、呼吸均有不同程度的增加,其中呼吸、心率增加到一定的程度后,又趋于平缓下降,呈“S”形曲线变化;当环境温度在35℃以下时,皮温高于毛丛温度,绵羊可以蒸发和非蒸发两种方式散热,环境温度接近35℃时,皮温与毛丛温度相等,绵羊只能以蒸发方式散热;高温下血清中K、Na、Cl、胆固醇的浓度显著降低(P<0.01或P<0.05),血清甲状腺激素T_3、T_4浓度显著增加(P<0.01),血清葡萄糖浓度也有所增加。     

脑缺血后HSP70表达的研究进展

Ritosso ( 1 962 )首先发现环境温度高于正常生理温度 4℃～ 6℃时 ,染色体上会出现特殊的膨突( Puffs) ,称其为热休克现象。后来 Tissieres等发现染色体的这一膨突与细胞中的一类特殊蛋白质的合成有关 ,并将这一类特殊蛋白质称为热休克蛋白 ( Heatshock protein,HSP)或热应激蛋白。近年来研究发现缺血性细胞损伤可以出现 HSP的表达 [1] ,还发现 HSP对受损细胞有保护作用。1　 HSP的分类　　 70 k Da家族是 HSP中最保守和最主要的一类 ,包括 68、70、72及 78k Da的 HSP。其中 HSP70是在缺血性脑损伤中研究最广泛的一种。氨基酸顺…     

昆虫的热休克反应和热休克蛋白

热休克（热激heatshock）是指短暂、迅速地向高温转换所诱导出的一种固定的应激反应。诱导该反应的温度在种与种之间有所不同。热休克反应最明显的特征是：伴随着正常蛋白质合成的抑制,一部分特殊蛋白质的诱导和表达增加,即为热休克蛋白（heatshockproteins,HSPs）。尽管热休克蛋白的合成也能被其它形式的应激反应所诱导,将它们认为是应激蛋白可能更恰当,但人们习惯上仍将这类蛋白质称为热休克蛋白。由于热休克反应和热休克蛋白是在果蝇（Drosophiliamelanogaster）中最初发现的,故在昆虫中,特别是果蝇等双翅目昆虫中研究得较深入…     

哺乳期高温经历导致布氏田鼠F1代的热中性区变窄

哺乳期是影响小型哺乳动物发育的关键时期，但关于哺乳叠加高温对后代代谢可塑性的影响，尚不清楚。为研究哺乳期母体(F0)高温经历对后代(F1代和F2代)能量代谢特征的影响，我们测定了哺乳期母体经历高温(30±1) oC的布氏田鼠(Lasiopodomys brandtii) F1代和F2代成体以及常温(23±1) oC经历的后代成体(作为对照)的体重和体温，采用开放式呼吸代谢仪测定不同环境温度暴露3 h后的代谢率，并计算热传导和呼吸商。哺乳期高温经历的F1代动物在成年期的体重显著低于常温对照组和高温经历的F2代动物。在5～33.5 oC环境温度范围内，布氏田鼠维持稳定的体温；35 oC高温胁迫时，常温组、高温经历F1代和F2代的体温均显著下降。常温组布氏田鼠的热中性区为27.5～33.5 oC，高温经历F1代的热中性区下临界温度点30 oC，热中性区比常温组变窄(30～33.5 oC)，高温经历F2代的热中性区与常温组相比无变化。在热中性区温度以上，热传导随环境温度的升高而显著增加，高温经历的F1代和F2代布氏田鼠热传导增加的起始温度点升高。呼吸商随环境温度的升高明显增加，但不受哺乳期高温...     

慢性复合应激对大鼠胰腺HAP1表达的影响

目的探讨慢性复合应激大鼠胰腺内胰岛内分泌细胞HAP1表达的变化及其意义。方法36只大鼠随机分为两组:慢性复合应激组和正常对照组。应激组动物无规律交替暴露于垂直旋转、睡眠剥夺、捆绑(6h/d)和夜间光照等慢性复合性应激,共6周;实验结束后,采用免疫组织化学和Western-blot等方法检测两组大鼠胰腺胰岛内分泌细胞内HAP1蛋白表达的变化。结果HAP1在大鼠胰腺内选择性表达于胰岛内分泌细胞中。与对照组相比,慢性复合应激组大鼠胰腺HAP1的表达明显增强(P<0.05)。结论6周慢性复合性应激可使大鼠胰腺中胰岛内分泌细胞的HAP1表达加强,提示HAP-1在慢性复合应激促进胰腺内分泌功能中可能发挥一定作用。     

荒漠沙蜥活动期间的体温节律

爬行动物的体温依赖于外界热环境的变化,本研究以荒漠沙蜥(Phrynocephalus przewalskii)为对象,收集其冬眠前活动期间的体温与地面和离地10 cm的空气温度,研究爬行动物体温节律性变化与环境温度的关系.研究结果表明,荒漠沙蜥在环境温度高于20℃后开始外出活动,其体温随着地面温度和空气温度的上升而逐步...     

小热应激蛋白与动物繁殖机能的关系研究进展

热应激是指机体受到超过本身体温调节能力的高温刺激而产生的非特异性防御反应,热应激蛋白是机体热应激反应发生后细胞新合成或合成数量增加的一类蛋白质,小分子热应激蛋白是热应激蛋白家族中重要的一类成员,作为分子伴侣在细胞的正常代谢和生理条件下表达和发挥作用。目前已证实小热应激蛋白还参与调控细胞增殖和凋亡、生物膜膜脂的流动性、核质穿梭作用、免疫应答和疾病治疗等。本综述分别就小热应激蛋白在雄性动物生精细胞发育过程中参与的增殖、分化及凋亡调控作用以及在雌性动物卵母细胞发育、成熟、妊娠维持和生育调节功能的研究进展做一概述,旨在为小热应激蛋白生物学功能深入研究提供参考。     

应激蛋白是否真正有用

应激蛋白(或热激蛋白)三十年前就已鉴定出来。现在终于到了可能成为商品的阶段。看来它们可能用来测定污染、改进医学诊断和治疗、提高rDNA蛋白的产量和监测发酵过程。在一些对生物不利的条件(如高温、缺氧、接触重金属和醇类)下,大多数应激蛋白会增加产生的数量,但有一些应激蛋白则与这些逆境并无关系。譬如,有一种与逆境无关的蛋白质——hsp70,试验证明它能使一些蛋白质透过细胞的膜层,并保护它们使它们避免因发生聚集作用而变性。但研究者认为,应激蛋白保护了细胞免受损害,却导致细胞进一步暴露在逆境之中。肿瘤细胞是这种情况的绝好例子,高温治疗(应用热力的冶疗)正越来越多地用来同放射治疗一起治疗肿瘤。但是第一次热疗后,肿瘤中应激蛋白的水平增加了,细胞对热的作     

PERK介导细胞应激反应的分子机制研究进展

内质网应激是未折叠蛋白质在内质网腔内的过量堆积和钙浓度失衡的一种应激反应,不仅参与细胞稳态的维持,而且在调节多种细胞应激反应方面具有重要意义。蛋白激酶R样内质网激酶(PERK)是介导内质网应激的三大关键信号分子之一,在细胞应激反应中具有明确和重要的调控作用。本文就PERK对基因毒应激、代谢应激和炎性应激的调节和分子机制做简要综述。     

热休克转录因子1的抗炎症作用

热休克转录因子1(heat shock factor 1, HSF1)是调节细胞保护性应激蛋白--热休克蛋白表达的主要转录因子,可被热应激、氧化应激等多种理化因素激活.近年研究表明,HSF1具有抗炎症作用:HSF1可抑制TNFα、IL-1β、M-CSF等致炎因子表达,促进IL-10等抗炎因子表达,并降低NF-κB、AP-1等致炎转录因子的活性.HSF1上调热休克蛋白和抑制炎症的双重活性,提示其很可能是联系应激反应和炎症反应的重要因子.     

Expression and localization of Hsps in the heart and blood vessel of heat-stressed broilers

The objective of this study was to investigate the kinetics of Hsp60, Hsp70, Hsp90 protein, and messenger RNA (mRNA) expression levels and to correlate these heat shock protein (Hsp) levels with tissue damage resulting from exposure to high temperatures for varying amounts of time. One hundred broilers were heat-stressed for 0, 2, 3, 5, and 10 h, respectively, by rapidly increasing the ambient temperature from 22 +/- 1 degrees C to 37 +/- 1 degrees C. Obvious elevations of plasma creatine kinase indicate damage to myocardial cells after heat stress. Hsp70 and Hsp90, and their corresponding mRNAs in the heart tissue of heat-stressed broilers, elevated significantly after 2 h of heat exposure and decreased quickly with continued heat stress. However, the levels of hsp60 mRNA in the heart of heat-stressed broilers increased sharply (P < 0.01) at 2 h of heat stress but then decreased quickly after 3 h, while the level of Hsp60 protein in the heart increased (P < 0.01) at 2 h of heat stress and maintained a high level throughout heat exposure. The results indicate that the elevation of the three Hsps, especially Hsp60 in heart, may be important markers at the beginning of heat stress and act as protective proteins in adverse environments. The reduction of Hsp signals in the cytoplasm of myocardial cells implies that myocardial cell lesions may have an adverse impact on the function of Hsps during heat stress. Meanwhile, the localization of Hsp70 in blood vessels of broiler hearts suggests another possible mechanism for protection of the heart after heat exposure.     

Heat shock causes oxidative stress and induces a variety of cell rescue proteins in Saccharomyces cerevisiae KNU5377

In this study, we attempted to characterize the physiological response to oxidative stress by heat shock in Saccharomyces cerevisiae KNU5377 (KNU5377) that ferments at a temperature of 40 degrees C. The KNU5377 strain evidenced a very similar growth rate at 40 degrees C as was recorded under normal conditions. Unlike the laboratory strains of S. cerevisiae, the cell viability of KNU5377 was affected slightly under 2 hours of heat stress conditions at 43 degrees C. KNU5377 evidenced a time-dependent increase in hydroperoxide levels, carbonyl contents, and malondialdehyde (MDA), which increased in the expression of a variety of cell rescue proteins containing Hsp104p, Ssap, Hsp30p, Sod1p, catalase, glutathione reductase, G6PDH, thioredoxin, thioredoxin peroxidase (Tsa1p), Adhp, Aldp, trehalose and glycogen at high temperature. Pma1/2p, Hsp90p and H+-ATPase expression levels were reduced as the result of exposure to heat shock. With regard to cellular fatty acid composition, levels of unsaturated fatty acids (USFAs) were increased significantly at high temperatures (43 degrees C), and this was particularly true of oleic acid (C18:1). The results of this study indicated that oxidative stress as the result of heat shock may induce a more profound stimulation of trehalose, antioxidant enzymes, and heat shock proteins, as well as an increase in the USFAs ratios. This might contribute to cellular protective functions for the maintenance of cellular homeostasis, and may also contribute to membrane fluidity.     

Tissue-Specific Induction of Hsp90 mRNA and Plasma Cortisol Response in Chinook Salmon following Heat Shock, Seawater Challenge, and Handling Challenge

In studying the whole-body response of chinook salmon (Oncorhynchus tshawytscha) to various stressors, we found that 5-hour exposure to elevated temperature (mean 21.6°C; + 10.6°C over ambient) induced a marked increase in Hsp90 messenger RNA accumulation in heart, brain, gill, muscle, liver, kidney, and tail fin tissues. The most vital tissues (heart, brain, gill, and muscle) showed the greatest Hsp90-mRNA response, with heart tissue increasing approximately 35-fold. Heat shock induced no increase in plasma cortisol. In contrast, a standard handling challenge induced high plasma cortisol levels, but no elevation in Hsp90 mRNA in any tissue, clearly separating the physiological and cellular stress responses. We saw no increase either in tissue Hsp90 mRNA levels or in plasma cortisol concentrations after exposing the fish to seawater overnight. Received October 1, 1999; accepted January 21, 2000     

Responses of cattle to the combined exposure to diurnal temperature rhythm (−5 to 25°C) and to simulated high-altitude (4,000 m)

Eight 1/2-year old calves were exposed in a climatized altitude chamber to the following four conditions: 400 and 4,000 m at constant T_a (17°C), 400 and 4,000 m at alternating T_a (–5° to 25°C). Each exposure lasted for 24 h and for the rhythmic conditions included a cold night and warm midday hours, supplemented by infrared heaters. During exposure, hourly measurements were made of heart rate, respiratory rate, rectal and three skin temperatures. Every 3-h blood samples were collected for the determination of 10 blood variables. The following main results were obtained: (a) Altitude alone caused increases in respiratory rate, heart rate, erythrocyte number, haemoglobin, specific gravity of blood and plasma, LDH and all four body temperatures. (b) In the rhythmic exposures, high correlation coefficients were found between ambient temperature on the one hand and skin temperatures (0.88 to 0.94), rectal temperature (–0.43) and respiratory rate (0.49) on the other hand. A change in ambient temperature by 1°C lead, on average, to a change in ear temperature by 1.2°C. (c) in response to falling ambient temperature during the night, rectal temperature and heart rate increased. This was interpreted as indicating a compensatory elevation in meta bolic heat production. At the same time, there was haemoconcentration as shown by elevations in erythrocyte number, haematocrit and haemoglobin. This haemoconcentration might have reflected splenic discharge, possibly supplemented by some loss of water from the plasma. (d) The warm environmental conditions around midday produced mild heat responses in terms of elevated values for respiratory rate, heart rate and body temperatures. (e) It is concluded that the rhythmic temperature with alternating stress of cold and mild heat, especially in combination with high altitude, was a strain on the animals and that they were forced to expend extra energy for combatting altitude- and temperature stress, energy which no longer would be available for productive processes.Presented at the Eight International Congress of Biometeorology, 9–14 September 1979, Shefayim, Israel.     

Adrenergic receptors mediate stress-induced elevations in extracellular Hsp72.

Heat-shock protein concentrations in the blood increase after exposure to a variety of stressors, including trauma and psychological stress. Although the physiological function of extracellular heat shock protein remains controversial, there is evidence that extracellular heat shock protein 72 (Hsp72) can facilitate immunologic responses. The signal(s) that mediate(s) the in vivo elevation of extracellular Hsp72 in the blood after stressor exposure remain(s) unknown. Here we report that Hsp72 increases in the circulation via an alpha1-adrenergic receptor-mediated signaling pathway. Activation of alpha1-adrenoceptors results in a rapid increase in circulating Hsp72, and blockade of alpha1-adrenoceptors prevents the stress-induced rise in circulating Hsp72. Furthermore, our studies exclude a role for beta-adrenoceptors, glucocorticoids, and ACTH in mediating stress-induced elevations in circulating extracellular Hsp72. Understanding the signals involved in elevating extracellular Hsp72 could facilitate the use of extracellular Hsp72 to bolster immunity and perhaps prevent exacerbation of inflammatory diseases during stress.     

Response of mice to continuous 5-day passive hyperthermia resembles human heat acclimation

Chronic repeated exposure to hyperthermia in humans results in heat acclimation (HA), an adaptive process that is attained in humans by repeated exposure to hyperthermia and is characterized by improved heat elimination and increased exercise capacity, and acquired thermal tolerance (ATT), a cellular response characterized by increased baseline heat shock protein (HSP) expression and blunting of the acute increase in HSP expression stimulated by re-exposure to thermal stress. Epidemiologic studies in military personnel operating in hot environments and elite athletes suggest that repeated exposure to hyperthermia may also exert long-term health effects. Animal models demonstrate that coincident exposure to mild hyperthermia or prior exposure to severe hyperthermia can profoundly affect the course of experimental infection and injury, but these models do not represent HA. In this study, we demonstrate that CD-1 mice continuously exposed to mild hyperthermia (ambient temperature ~37°C causing ~2°C increase in core temperature) for 5 days and then exposed to a thermal stress (42°C ambient temperature for 40 min) exhibited some of the salient features of human HA, including (1) slower warming during thermal stress and more rapid cooling during recovery and (2) increased activity during thermal stress, as well as some of the features of ATT, including (1) increased baseline expression of HSP72 and HSP90 in lung, heart, spleen, liver, and brain; and (2) blunted incremental increase in HSP72 expression following acute thermal stress. This study suggests that continuous 5-day exposure of CD-1 mice to mild hyperthermia induces a state that resembles the physiologic and cellular responses of human HA. This model may be useful for analyzing the molecular mechanisms of HA and its consequences on host responsiveness to subsequent stresses.     

Development of sweating ability in winter- and summer-born Friesian calves aged 1 to 6 weeks

Sweating rate, rectal and skin temperatures and respiration rate were measured at weekly intervals from 7 days of age (for 4 weeks in Experiment 1; 6 weeks in Experiment 2) in winter- and summer-born Friesian calves exposed to a temperature of 39°C dry bulb and 32°C wet bulb in a climate chamber. Four calves were studied in each season in both experiments. In Experiment 1, ambient temperatures were from 3° to 9°C higher in early summer than in late winter. During each 39°C exposure, sweating rate increased from basal levels of 40–90 to plateau levels of 120–300 g/m² per h after 90–120 min. The increase in sweating rate with age was most pronounced in winter-born calves, but summer-born calves had higher values at 1 week of age (167±52.4 vs 94.4±30.1 g/m² per h). Seasonal differences in ambient temperature were greater in Experiment 2 (11° to 17°C). In this case summer-born calves had higher sweating rates at each age (plateau values of 220–320 g/m² per h), and showed a more rapid increase in sweating rate during each 39°C exposure than winter-born calves (plateau values of 100–250 g/m² per h). The results demonstrate major changes in sweating competence during the first 4–6 weeks of life in Friesian calves, a quite pronounced effect of season (ambient temperature) on the levels of sweating achieved, and indicate that low sweating rates in newborn calves are a contributing factor in deaths due to hyperthermia in semi-arid grazing areas.     

Induction of the 72-kilodalton heat shock protein and protection from ultraviolet B-induced cell death in human keratinocytes by repetitive exposure to heat shock or 15-deoxy-delta(12,14)-prostaglandin J2

It has been demonstrated that hyperthermia protects keratinocytes from ultraviolet B (UVB)-induced cell death in culture and in vivo. This effect is mediated by the antiapoptotic effect of heat shock proteins that are transiently induced after exposure to heat at sublethal temperatures. Consequently, induction of Hsp has been proposed as a novel means of photoprotection. However, in the face of daily UVB exposure of human skin in vivo, this approach would not be useful if keratinocytes become less sensitive to Hsp induction with repeated exposure to the inducing agent. The aim of this study was to investigate whether repeated exposure to hyperthermia or to the stress protein activating cyclopentenone prostaglandin 15-deoxy-delta(12,14)-prostaglandin J2 (15dPGJ2) leads to adaptation of the cells, attenuation of the heat shock response, and abrogation of the protective effect. Normal human epidermal keratinocytes (NHEK) and the carcinoma-derived cell line A431 were exposed to either 42 degrees C or to 15dPGJ2 for 4 hours at 24-hour intervals for 4 consecutive days. The intracellular level of the 72-kDa heat shock protein (Hsp72) was determined by enzyme-linked immunosorbent assay (ELISA). Cells were exposed to UVB from a metal halide source after the last heat or 15dPGJ2 treatment, and survival was determined 24 hours after exposure by a MTT assay. Our results demonstrate that (1) heat shock and 15dPGJ2 are potent inducers of Hsp72 expression and lead to increased resistance to UVB-induced cell death in human keratinocytes; (2) re-exposure to heat shock leads to a superinduction without attenuation of the absolute increase in Hsp72 and of its UVB-protective effect; (3) the UVB tolerance induced by 15dPGJ2 is enhanced by repeated exposure without a further increase of Hsp72; (4) repeated heat shock and 15dPGJ2 up to a concentration of 1 microg/mL have no influence on cell growth over a period of 4 days. We conclude that through repeated exposure to Hsp-inducing factors, stress tolerance can be maintained without additional toxicity in human keratinocytes. These results provide a basis for the development of nontoxic Hsp inducers that can be repeatedly applied without loss of effect.     

Hyperthermia assists survival of astrocytes from oxidative-mediated necrotic cell death.

In response to many stresses and pathologic states, including different models of nervous system injury, cells synthesize a variety of proteins, most notably the inducible 72 kDa heat shock protein 70 (Hsp70), which plays important roles in maintaining cellular integrity and viability. We report here that cultured astrocytes from rat diencephalon express high levels of Hsp70 upon exposure to elevated temperatures, and are less vulnerable to a subsequent oxidative stress. Complex oxidative stress was induced by exposure of astrocytes to an aqueous extract of tobacco smoke. This resulted in both glutathione and ATP depletion, along with cell death that proceeded through a necrotic pathway. Pretreatment of cultures with the glutathione replenishing agent, N-acetyl-L-cysteine, prevented glutathione and ATP loss as well as necrotic cell death. Thermal stress also protected astrocytes from necrotic cell death but without affecting glutathione or ATP levels. We propose that heat shock protects astrocytes from necrosis induced by oxidative stress, probably as a result of Hsp70 synthesis, through an antioxidant-ATP independent mechanism. As Hsp70 may transfer from glial to neuronal cells, its synthesis by astrocytes may represent an important survival mechanism by which astrocytes protect neurons against oxidative-mediated cell death.