The hormetic effects of hypergravity on longevity and aging

This paper reviews the literature on the effects of hypergravity (HG, gravity levels higher than 1g, the terrestrial gravity) on longevity and aging. The different studies showed that life-long exposures to high gravity levels decreased longevity and accelerated the age-related decline observed on some physiological and behavioral variables. In contrast, chronic exposure to HG increased resistance to heat in young and middle-aged Drosophila melanogaster. A short exposure to HG at the beginning of adult life increased male longevity and delayed behavioral aging in D. melanogaster. All these results show that HG acts as a hormetic factor. Long exposures to HG have deleterious effects on longevity and aging, whereas short exposures have beneficial effects. Some potential mechanisms of action of the beneficial effects of HG are also reviewed here. However, the ones tested so far (heat shock proteins and antioxidant defense) have proven unable to explain the hormetic effects of HG and their mechanisms of action are still unknown.     

热应激和短暂心肌缺血对大鼠心肝组织热休克蛋白70表达的影响

目的探讨热应激及短暂心肌缺血对大鼠心、肝组织损伤及热休克蛋白（HSP70）表达的影响。方法24只雄性SD大鼠随机分为：对照组、假手术组、热休克组和短暂心肌缺血组,每组6只,应激后20h取心、肝组织,采用Western blotting、免疫组化及HE染色方法,观察大鼠心、肝组织的病理变化和HSP70的表达。结果（1）热应激及短暂心肌缺血后大鼠心、肝组织均有病理改变且HSP70表达与对照相比均显著增加（P〈0．05）;（2）短暂心肌缺血后心肌中HSP70表达量显著高于热应激后的表达量（P〈0．05）,而肝脏在两种刺激后HSP70表达量差异无统计学意义（P〉0．05）。结论短暂心肌缺血对心脏组织中HSP70表达的影响强于热应激,而对肝脏的影响两者无显著差异,这可能与不同刺激引起心、肝组织中HSP70表达机制不同有关。     

The early signal substances induced by heat stress in brains of mice

To study the effects of early signal substances induced by heat stress in brains of Kunming mice, six-month-old mice (n = 72) were pretreated with heat stress and subsequent ischemia/reperfusion by clipping of their bilateral cervical common arteries for 7 min. According to different treatments, animals were randomly divided into four groups: (1) normal control group; (2) heat stress pretreatment followed by ischemia and reperfusion group (HS/IR); (3) ischemia and reperfusion group (IR); (4) heat stress group (HS). Animals in the later three groups were subdivided into 3 subgroups (1 day, 4 days, 14 days), respectively. The changes in the expression of cAMP response element binding protein (CREB) and calcitonin gene-related peptide (CGRP) were detected by immunohistochemistry and computer image analysis methods. The results showed that compared with the normal group, the expressions of CREB in the hippocampal CA1 region increased significantly in the HS, HS/IR and IR groups (P < 0.05). Compared to the normal group, heat stress could result in CGRP excretion and redistribution in the cerebrum, with the highest level in the 4 d HS/IR group. Following heat stress, CGRP immunoreactivity was observed in varicose fibers and neuronal perikarya within the CA1 region. The results indicate that heat stress can induce CREB expression, which in turn stimulates CGRP secretion.     

Induction of heat shock proteins for protection against oxidative stress

Heat shock proteins (Hsps) have been studied for many years and there is now a large body of evidence that demonstrates the role of Hsp upregulation in tissue and cell protection in a wide variety of stress conditions. Oxidative stress is known to be involved in a number of pathological conditions, including neurodegeneration, cardiovascular disease and stroke, and even plays a role in natural aging. In this review we summarize the current understanding of the role of Hsps and the heat shock response (HSR) in these pathological conditions and discuss the therapeutic potential of an Hsp therapy for these disorders. However, although an Hsp based therapy appears to be a promising approach for the treatment of diseases that involve oxidative damage, there are some significant hurdles that must be overcome before this approach can be successful. For example, to be effective an Hsp based therapy will need to ensure that the upregulation of Hsps occurs in the right place (i.e. be cell specific), at the right time and to a level and specificity that ensures that all the important binding partners, namely the co-chaperones, are also present at the appropriate levels. It is therefore unlikely that strategies that involve genetic modifications that result in overexpression of specific Hsps will achieve such sophisticated and coordinated effects. Similarly, it is likely that some pharmaceutical inducers of Hsps may be too generic to achieve the desired specific effects on Hsp expression, or may simply fail to reach their target cells due to delivery problems. However, if these difficulties can be overcome, it is clear that an effective Hsp based therapy would be of great benefit to the wide range of depilating conditions in which oxidative stress plays a critical role.     

Aspirin relieves the calcification of aortic smooth muscle cells by enhancing the heat shock response

ContextVascular calcification is a major complication of chronic renal failure, which has been identified as an active process partly driven by osteogenic transition of vascular smooth muscle cells (VSMCs). Aspirin could prevent cardiomyocyte damage by inducing heat shock response.ObjectiveThis study investigates the effect of aspirin on alleviating VSMC calcification.Materials and methodsAn in vitro VSMC calcification model was established by 10-day calcification induction in osteogenic medium. VSMCs were grouped as following: control group (normal medium), calcified group (osteogenic medium) and treated group (osteogenic medium with 1 or 4 mmol/L aspirin). VSMC calcification was evaluated by calcified nodules formation, intracellular calcium concentration and osteoblastic marker (OPN and Runx2) expression.ResultsAfter 10-day culture, the intracellular calcium concentration in calcified group was significantly higher than that in control group (1.16 ± 0.04 vs. 0.14 ± 0.01 μg/mg, p < 0.01), but significantly reduced in 1 mmol/L aspirin treated group (0.74 ± 0.05 μg/mg, p < 0.01), and 4 mmol/L aspirin treated group (0.93 ± 0.03 μg/mg, p < 0.01). The elevated expression of OPN and Runx2 induced by osteogenic medium was significantly relieved after 1 or 4 mmol/L aspirin treatment. The expression of HSF1, HSP70 and HSP90 was decreased in calcification-induced VSMCs, but significantly increased after treatment of aspirin. Furthermore, inhibition of HSP70 (or HSP90) by small-molecule inhibitor or small interfering RNA could partially abolish the anti-calcification effect of aspirin, proved by the changes of intracellular calcium concentration and osteoblastic marker expression.Discussion and conclusionsAspirin could relieve the calcification of VSMCs partially through HSP70- or HSP90-mediated heat shock response. These findings expanded the understanding of aspirin pharmacology, and imply that local induction expression of HSPs might be a potential therapeutic strategy for the prevention and therapy of vascular calcification.     

格尔德霉素通过诱导热休克蛋白反应抑制DA能神经元蛋白水解应激的研究

目的探讨格尔德霉素(geldanamycin,GA)通过诱导热休克蛋白(HSP)反应抑制α-突触核蛋白(α-syn)异常表达,加强泛素蛋白酶体降解功能的神经保护作用。方法鱼藤酮作用于NGF诱导的PC12细胞建立α-syn胞质内过表达细胞模型,MTT法检测GA不同浓度及用药时程条件下的细胞活力,应用Western blot技术及共聚焦免疫荧光双标染色观察GA预处理后细胞内HSP70和α-syn的表达。荧光分光光度计测量各组细胞内蛋白酶体水解酶活性的变化。结果MTT示GA20～300nmol·L-1预处理使细胞活力呈浓度依赖性上升,吸光度分别上升至正常的65%、76%、85%和94%(鱼藤酮组为59%,P<0·01),而GA与鱼藤酮同时给药或作用于其后20h细胞活力无明显变化。Western blot结果提示GA预处理使HSP70表达上升至正常的3倍左右。共聚焦显微镜观察显示α-syn过表达现象得以抑制,并证实两者的共定位现象。酶活性测定提示GA预处理使类胰蛋白酶,类糜蛋白酶活性明显增强,荧光指数分别上升至10·4±1·61和96·0±4·77(鱼藤酮组为7·9±0·90和82·4±3·51,P<0·05),PgH水解酶活性也轻度上升。结论格尔德霉素可诱发热休克蛋白反应,主要通过HSP70的作用抑制α-syn的异常表达,促进泛素蛋白酶体降解功能,减轻蛋白水解应激反应,发挥神经保护效应。     

Non-binding site modulation of G protein-coupled receptor signalling

G protein-coupled receptors (GPCRs) are by far the most successful drug targets yet known, due to their key role in cellular communication. Historically, these drugs bind to the same site at which the endogenous agonist interacts. However, as the details of cell signalling are clarified, it is becoming apparent that there are many other sites at which GPCR signalling can be modulated. Furthermore, the emerging ability to block protein-protein interactions with small molecules means that these sites are now also viable therapeutic targets. Potential points of therapeutic intervention of GPCR signalling are at the level of the G protein, where the activities of both a and βγ subunits could be controlled; at multiple effectors such as the adenylyl cyclases, phospholipases and phosphodiesterases; at regulatory proteins such as the regulators of G protein signalling (RGS) proteins or receptor kinases; or at the mitogenic pathways, which offer many sites for intervention. By targeting these sites, perhaps just one arm of the multiple pathways through which a receptor works can be modified, thus providing a greater degree of therapeutic selectivity and specificity than can be attained using receptor agonists or antagonists.     

Oxidative stress and stress signaling： menace of diabetic cardiomyopathy

Cardiovascular disease is the most common cause of death in the diabetic population and is currently one of the leading causes of death in the United States and other industrialized countries. The health care expenses associated with cardiovascular disease are staggering, reaching more than 350 billion dollars in 2003. The risk factors for cardiovascular disease include high fat/cholesterol levels, alcoholism, smoking, genetics, environmental factors and hypertension, which are commonly used to gauge an individual's risk of cardiovascular disease and to track their progress during therapy. Most recently, these factors have become important in the early prevention of cardiovascular diseases. Oxidative stress, the imbalance between reactive oxygen species production and breakdown by endogenous antioxidants, has been implicated in the onset and progression of cardiovascular diseases such as congestive heart failure and diabetes-associated heart dysfunction (diabetic cardiomyopathy). Antioxidant therapy has shown promise in preventing the development of diabetic heart complications. This review focuses on recent advances in oxidative stress theory and antioxidant therapy in diabetic cardiomyopathy, with an emphasis on the stress signaling pathways hypothesized to be involved. Many of these stress signaling pathways lead to activation of reactive oxygen species, major players in the development and progression of diabetic cardiomyopathy.     

热休克蛋白70调节突触融合蛋白Syntaxin 1在哮喘中的表达

目的探讨热休克蛋白70(heat shock protein 70,HSP70)对突触融合蛋白Syntaxin1(SYX1)在哮喘大鼠肺组织中表达水平的调节及相互作用。方法 30只健康Wistar大鼠按随机原则分为对照组、哮喘组、哮喘+地塞米松组,每组10只。通过卵清蛋白(ovalbumin,OVA)致敏、激发建立哮喘大鼠模型,采用免疫组织化学、逆转录PCR及蛋白免疫印迹检测3组间HSP70及SYX1基因和蛋白表达水平,免疫共沉淀技术检测HSP70与SYX1的相互关系。结果与对照组比较,哮喘组HSP70及SYX1基因和蛋白表达水平均增加,差异有统计学意义(P<0.05,P<0.05);与哮喘组比较,哮喘组+地塞米松组HSP70及SYX1基因与蛋白表达水平均降低,差异有统计学意义(P<0.05,P<0.05),但与正常对照组比较,差异均无统计学意义(P>0.05,P>0.05)。免疫共沉淀结果显示在哮喘大鼠肺组织中HSP70与SYX1存在相互作用。结论 HSP70及SYX1在哮喘肺组织中表达水平均明显增高,HSP70通过调节SYX1表达水平及相互作用共同参与哮喘的发病机制,且其表达受地塞米松的抑制,为临床寻找药物干预新的靶点提供了理论依据。     

脂筏在细胞信号特异性调节钾离子通道功能中的作用

钾离子通道在稳定细胞膜电位和调节细胞兴奋性等方面发挥重要作用,目前的研究主要集中在其信号转导通路的上下游的参与分子方面。细胞在接受刺激后,众多的信号通路同时在在一片很小的细胞膜上发生,此间必然存在着一个空间上的调节来协调不同通路的"特异性"转导。脂筏即是其中参与信号转导的平台之一。该文即对脂筏在钾离子通道调节中的作用及目前研究进展进行综述。     

Central leptin gene delivery evokes persistent leptin signal transduction in young and aged-obese rats but physiological responses become attenuated over time in aged-obese rats

The purpose of this study was to determine if long-term leptin treatment desensitizes leptin signal transduction and the subsequent downstream anorexic and thermogenic responses in normal and leptin-resistant age-related obese rats. To this end, we administered, i.c.v., recombinant adeno-associated virus encoding rat leptin cDNA (rAAV-leptin) or control virus into young and aged-obese rats and after 9 or 46 days, examined food intake, oxygen consumption, body weight, serum leptin, STAT3 phosphorylation, hypothalamic NPY and POMC mRNAs, and UCP1 expression and protein level in brown adipose tissue (BAT). In young rats, rAAV-leptin depleted body fat and both anorexic and thermogenic mechanisms contributed to this effect. Moreover, leptin signal transduction was not desensitized, and there were persistent physiological responses. Similarly, in the aged-obese rats, there was unabated leptin signal transduction, however, both the anorexic and thermogenic responses completely attenuated sometime after day 9. This attenuation, downstream of the leptin receptor, may be contributing to the leptin-resistance and age-related weight gain in these aged-obese rats. Finally, in young rats, although the initial responses to rAAV-leptin were dominated by anorexic responses, by 46 days, the predominant response was thermogenic rather than anorexic, suggesting that energy expenditure may be an important component of long-term weight maintenance.     

不同应激刺激后大鼠心脏、肝脏热休克蛋白(HSP70)的产生规律

目的 探讨热处理、心肌缺血及缺血预适应后大鼠心脏、肝脏热休克蛋白(HSP70)的产生规律。方法 采用聚丙烯酰胺凝胶电泳法测定不同应激刺激条件下各组动物心、肝组织产生HSP70的含量。结果 心肌组织对热休克、缺血等外源性应激刺激呈高敏感性，且随刺激形式的不同而产生的热休克蛋白含量也不同；而肝脏的反应则比较迟钝，对多数损伤反应的应答呈现一致性，但仍然显著高于对照组。结论 采用热休克蛋白作为研究指标时，应考虑到它的多源性和非特异性。慎下研究结论。     

G蛋白介导的信号传递在阿尔采末病中的功能变化

阿尔采末病 (AD)是一种神经退行性疾病 ,病理特点主要有 β 淀粉样蛋白的沉积和神经纤维缠结的形成。一直以为AD脑中神经元功能受损与突触后受体变化无关 ,但近来越来越多的证据表明中枢神经递质受体 /G蛋白介导的腺苷酸环化酶和磷酯酰肌醇水解信号转导途径在AD病程中均受到不同程度的损害 ,这亦解释了神经递质替代疗法在治疗AD中疗效有限的原因 ,同时为进一步研究和开发防治AD新药提供新思路     

黄芩苷对D半乳糖诱导衰老大鼠拮抗脑老化糖基化氧化应激及胰岛素抵抗作用

目的 观察黄芩苷( baicalin,Bai)对D-半乳糖(D-gal)诱导大鼠体内蛋白非酶糖基化-氧化应激、醛糖还原酶(AR)活性、血糖、胰岛素抵抗(IR)及空间探索能力的作用.方法 除空白对照组外,其余大鼠均采用腹腔注射( ip) D-gal 150 mg·kg-1,qd×70d致病.D-gal处理大鼠28 d后,将大鼠按体重均衡随机分成5组,每组15只:模型对照组(二甲双胍150 ng·kg-1、氨基胍150 mg·kg-1)以及Bai高和低剂量组(300 ng·kg-1和150 mg·kg-1),然后继续ip D-gal处理,同时灌胃给予不同药物或蒸馏水(10ml·kg-1),qd×42 d;实验结束时,观察药物对D-半乳精诱导大鼠血糖(FBG)、果糖胺(FRA)、糖化血红蛋白(HbAlc)、晚期糖基化终末产物( AG Es)、胰岛素和丙二醛(MDA)含量,并计算胰岛素敏感指数(ISI),醛糖还原酶(AR)和超氧化物歧化酶( SOD)活性,以及测定Moris水迷宫空间探索能力的作用.结果 与空白对照组比较,D-gal处理大鼠出现FBG、FRA、HbAIc、AGEs和MDA及胰岛素含量增高,SOD活性和ISI降低,红细胞内AR活性增强(P＜0.01 );二甲双胍、氨基胍以及Bai高和低剂量,均能不同程度降低D-gal诱导大鼠FBG、FRA、HbAlc、AGEs和胰岛素含量(P＜ 0.01或0.05),提高ISI( P＜ 0.01),降低MDA含量而提高SOD活性,并明显抑制AR活性(P＜0.01或0.05),提高大鼠空间探索能力.结论 Bai能对抗D-gal致衰老大鼠IR,改善胰岛素敏感性,抑制糖基化-氧化应激反应、多元醇通路代谢以及炎症反应,改善大鼠空间探索能力.Bai的上述作用,呈量效关系.     

水飞蓟宾对D-半乳糖诱导衰老大鼠抑制糖氧化应激反应及改善学习记忆作用

目的:观察水飞蓟宾对D-半乳糖(D-gal)诱导衰老大鼠糖化氧化应激反应及学习记忆作用的影响。方法:采用D-gal诱导衰老大鼠模型;采用Morris水迷宫测定法检测大鼠学习记忆能力。实验结束后测定大鼠血浆糖化血红蛋白(HbA1c)、血浆非酶糖基化终产物(AGEs)和果糖胺(FRA)含量、红细胞醛糖还原酶(AR)活性及脑组织超氧化物歧化酶(SOD)活性和丙二醛(MDA)、AGEs含量。结果:水飞蓟宾150mg/kg和75mg/kg均能明显抑制D-gal诱导的AR活性增高(P<0.01),降低FRA、HbA1c和AGEs含量(P<0.01或P<0.05),能不同程度地降低大鼠脑组织AGEs和MDA含量,提高SOD活性(P<0.01)。结论:水飞蓟宾对D-半乳糖所致衰老大鼠学习记忆障碍具有保护作用,能增强学习记忆能力,其机制可能与抑制糖氧化应激反应有关。     

热休克预处理对对乙酰氨基酚所致小鼠急性肝损伤的保护作用

目的探讨热休克预处理对对乙酰氨基酚(AAP)诱导的小鼠急性肝损伤的保护作用。方法40℃分别热休克(HS)处理小鼠10min(HS10组)、20min(HS20组)和30min(HS30组),室温恢复8h后,小鼠ip给予AAP 550mg·kg-1诱导急性肝损伤,分别于AAP后0,6,24,42和72h进行相关指标检测。赖氏法检测小鼠血清中天冬氨酸转氨酶(AST)和丙氨酸转氨酶(ALT)活性,HE染色进行病理学分析,免疫组化法检测给予AAP后0 h,小鼠肝热休克蛋白70(HSP70),细胞色素P4501A2(CYP1A2)和增殖细胞核抗原(PCNA)的表达,Western印迹法检测给予AAP后0,6,24,42和72h时小鼠PCNA的表达。结果与AAP对照组相比,HS20组小鼠血清中AST和ALT酶活水平显著降低(P<0.05),而HS10组和HS30组小鼠无显著差异。与AAP对照组相比,HS20显著降低了AAP诱导的小鼠肝损伤程度(P<0.05),而HS10和HS30未显著降低肝损伤的程度。HS20显著诱导了小鼠肝HSP70(P<0.01),CYP1A2(P<0.01)和PCNA(P<0.05)的表达,而HS10和HS30显著诱导了小鼠肝HSP70和CYP1A2(P<0.05)的表达,但未明显诱导PCNA的表达。与HS10和HS30相比,HS20更加显著地诱导了HSP70和CYP1A2的表达(P<0.05)。HS20组小鼠在注射AAP后0,6,24,42和72h,小鼠肝PCNA的表达均显著高于AAP对照组(P<0.05)、HS10和HS30组(P<0.05)。结论 40℃热休克预处理20min可以有效降低AAP诱导的小鼠急性肝损伤程度,加速肝损伤后的修复。     

A novel quinone-based derivative (DTNQ-Pro) induces apoptotic death via modulation of heat shock protein expression in Caco-2 cells

Background and purpose:

The resistance of human colon adenocarcinoma cells to antineoplastic agents may be related to the high endogenous expression of stress proteins, including the family of heat shock proteins (HSPs). Recently, a quinone-based pentacyclic derivative, DTNQ-Pro, showed high cytotoxic activity in human colon carcinoma cell lines. The aim of the present study was to determine the precise cellular mechanisms of this cytotoxic action of DTNQ-Pro.

Experimental approach:

Using human colorectal carcinoma-derived Caco-2 cells as a model, we studied the effects of DTNQ-Pro on cellular viability and oxidative stress; HSP70 and HSP27 accumulation; and cell cycle, differentiation and apoptosis.

Key results:

Incubation of Caco-2 cells with DTNQ-Pro reduced cell growth and increased the levels of reactive oxygen species in mitochondria. After 48 h of treatment, cells surviving showed an increased expression of Mn-superoxide dismutase (SOD), nitric oxide production and membrane lipid peroxidation. Treatment with DTNQ-Pro decreased HSP70 expression, and redistributed HSP27 and vimentin within the cell. DTNQ-Pro down-regulated the expression of A and B cyclins with arrest of the cell cycle in S phase and increased cellular differentiation. A second treatment of Caco-2 cells with DTNQ-Pro induced cellular death by activation of the apoptotic pathway.

Conclusions and implications:

DTNQ-Pro causes Caco-2 cell death by induction of apoptosis via inhibition of HSP70 accumulation and the intracellular redistribution of HSP27. These findings suggest the potential use of DTNQ-Pro in combination chemotherapy for colon cancer.     

Cardiac mitochondrial complex activity is enhanced by heat shock proteins

1. Prolonged ischaemia and reperfusion in heart transplantation results in mitochondrial dysfunction and loss of cardio-energetics. Improved myocardial tolerance to ischaemia-reperfusion can be increased by de novo synthesis of heat shock protein (Hsp) groups, transiently expressed following mild hyperthermic or oxidative stress. Consideration of the roles of various Hsp in ischaemic-reperfused myocardium can provide new insights into potential therapeutic adjuncts to cardiac surgery. 2. Several Hsp classes have been located within or in association with mitochondrial elements. Cardiac Hsp research has focused primarily on the 70 kDa group, involved in protein folding functions within the cytosol and matrix. Similarly, Hsp 60 and 10 have been shown to form a mitochondrial chaperonin complex conferring protection to ischaemia-challenged myocytes. Equally pertinent is Hsp 32, an isoform of the haem-metabolizing enzyme heme oxygenase. 3. Our studies have shown that mitochondrial respiratory enzyme activity can be protected by Hsp, affording protection to cardiac energetics during preservation for transplantation. Upregulation of Hsp 32, 60 and 72 in rats, achieved by mild hyperthermic stress, improved cardiac function, ultrastructure and mitochondrial respiratory and complex activities in ex vivo perfused hearts subjected to cold cardioplegic arrest and ischaemia-reperfusion. Pre-ischaemic mitochondrial complex activities were increased in heat stress versus sham-treated groups for complex I, IV and V. 4. Investigation of the direct effect of upregulation of Hsp 72 by gene transfection resulted in a similar pattern of response, with increased complex I activity and improved ventricular function. 5. These studies provide the first evidence of Hsp-mediated enhancement of mitochondrial energetic capacity. Enhanced protection of mitochondrial energetics, as a result of increased Hsp expression, contributes to the recovery of myocardial function in ischaemia-reperfusion.