浅水应激后黄斑蓝子鱼生理指标变化及牛磺酸的抗应激作用简

研究报道黄斑蓝子鱼受到短暂(4min)浅水应激后鱼体相关应激指标的变化及应激后20、40、60、80min时的恢复情况,以及牛磺酸的抗应激作用。结果表明,浅水应激后,该鱼血清肾上腺素浓度显著升高(P0.05),从应激前的(2.00±0.22)ng/mL达到应激后的(15.12±1.04)ng/mL,之后逐渐恢复到应激前水平;皮质醇和胆固醇浓度没有显著性变化(P0.05);葡萄糖浓度在应激后20min达到最大值(7.10±0.38)mmol/L,是应激前(2.15±0.02)mmol/L的约3.5倍(P0.05)。应激后60min时,脑中HSP70 mRNA的表达量达到最大值,为应激前的11.54倍(P0.05)。0.02‰牛磺酸浸泡能够显著降低蓝子鱼应激后的血清肾上腺素和葡萄糖水平以及脑HSP70 mRNA表达量(P0.05)。结果说明,交感神经-嗜铬组织系统可能是黄斑蓝子鱼的急性应激途径之一,鱼体通过释放肾上腺素来提高血糖浓度以满足应激时的能量需求,同时通过提高细胞HSP70的表达水平来增强鱼体的保护作用;牛磺酸具有一定的抗应激作用。     

冷拘束应激对大鼠心脏和肝脏HSP70表达及血清中CK、ALT含量的影响

目的通过研究冷拘束应激中大鼠心脏和肝脏组织热休克蛋白（HSP70）表达量以及血清中肌酸激酶（CK）、谷丙转氨酶（ALT）含量的变化,探讨冷拘束应激对心脏和肝脏的影响和差异。方法选取50日龄清洁级大鼠77只,随机分为7组,即0h,0.5h,1.0h,1.5h,2.0h,2.5h,3.0h。采用拘束冷应激法,应激相应时间后,用免疫组织化学方法观察大鼠心脏和肝脏组织HSP70的表达,并检测血清中CK和ALT含量。结果 （1）心脏中HSP70表达量随着应激时间的延长而增加,1.5h组较0h组有明显的增加（P〈0.05）,而2.0h后有极明显的增加（P〈0.01）。（2）肝脏中HSP70表达量随应激时间的延长呈缓慢增加,仅3.0h组有较明显的增加,与0h组、0.5h组及1.0h组比较有显著差异（P〈0.05）。（3）应激开始阶段大鼠血清中的CK含量迅速上升,之后平缓升高;大鼠血清中的ALT含量呈现上升趋势,2.5h以前上升较平缓,2.5h以后急骤升高。结论冷拘束应激可使大鼠心脏中HSP70的表达量和血清中CK含量在较短的时间内显著上升,且随着时间的增加而递增,而肝脏中HSP70的表达量和血清中ALT含量在较短的时间内无明显变化,只有在3.0h时才显著增加,提示心脏对冷拘束应激较敏感,而肝脏对冷拘束应激有较强的耐受性。     

热应激对大鼠睾丸HSPs mRNA表达的影响

目的:观察和分析大鼠睾丸局部短暂热应激对HSP70、HSP90、HSP105 mRNA表达的影响。方法:Wistar雄性大鼠随机分为5组:正常对照(N)组、热应激0天(H0)组、热应激5天(H5)组、热应激10天(H10)组、热应激15天(H15)组。N组睾丸局部22℃水浴20 min,其余各组均睾丸局部43℃水浴20 min。采用HE染色观察组织形态学变化,采用Real Time PCR的方法检测HSP70、HSP90、HSP105 mRNA的表达量。结果:HE染色镜下观察结果显示:与N组相比,H5组部分曲细精管萎缩,生精细胞明显消失,H10组、H15组大部分曲细精管萎缩,生精细胞大量消失。HE染色形态计量结果显示:与N组相比,H5组、H10组、H15组睾丸实质体积比明显减小(p0.05),睾丸间质体积比明显增加(P0.05)。RT-PCR结果显示:与N组相比,H0组HSP70 m RNA的表达H0组明显增高(p0.05),H5组、H10组、H15组HSP90 m RNA的表达明显降低(P0.05),H5组HSP105 m RNA的表达明显降低(P0.05)。结论:HSP70、HSP90、HSP105 m RNA的表达在热应激后都会发生变化,变化的具体情况不尽相同,推测它们热应激后在生殖细胞凋亡过程中发挥不同的作用有关,并且和组织的损伤有密切的联系。     

离体大鼠心肌内质网应激模型构建条件的优化

目的探讨构建体外心肌内质网应激（endoplasmic reticulum stress,ERS）模型的方法及实验条件。方法应用Langendorff灌流装置制作大鼠心脏离体缺血/再灌注模型,采用PowerLab系统持续监测血流动力学参数,Western blot检测缺血（停止灌流）不同时间/再灌注120 min后心肌ERS标志性分子糖调节蛋白（GRP）78的表达,并检测C/EBP同源蛋白（CHOP）的表达;逆转录-聚合酶链反应（RT-PCR）检测二者mRNA的表达;体外孵育心肌组织切片,分别应用不同浓度的衣霉素（tunicamycin,Tm）和二硫苏糖醇（dithiothreitol,DTT）处理3 h和6 h,Western-blot检测心肌GRP78及CHOP的表达。结果与对照组相比,离体灌注心脏缺血40 min/再灌注120 min时,心肌GRP78表达最高（P〈0.01）,CHOP蛋白、GRP78 mRNA及CHOP mRNA表达均明显升高（P〈0.01,P〈0.05和P〈0.05）,同时,各项血流动力学参数受损（均P〈0.01）;Tm 10μg/mL和DTT 2 mmol/L孵育心肌组织切片3 h时,GRP78表达较对照组显著升高（均P〈0.001）,CHOP表达亦均明显升高（P〈0.05和P〈0.01）。结论使用离体大鼠心脏缺血/再灌注和孵育心肌组织切片的方法,均可成功构建体外心肌ERS模型。     

热应激对齐口裂腹鱼非特异性免疫功能及细胞凋亡的影响

为研究热应激及恢复对齐口裂腹鱼（Schizothorax prenanti）机体损伤、非特异性免疫功能和细胞凋亡的影响,测定了热应激前（19℃,对照组）、热应激（27℃,0、2h、4h、8h、12h,实验组）及恢复适温6h后（19℃,恢复组）的非特异性免疫相关生理生化指标及细胞凋亡率。结果表明,超氧化物歧化酶（Superoxide dismutase,SOD）在应激0、4h、8h、12h后活性上升,应激0和12h与应激前差异极显著（P<0.01）;髓过氧化物酶（Myeloper oxidase,MPO）在热应激4h达到最大值;谷草转氨酶（Glutamic-oxalacetic transaminase,GOT）的活性实验组与对照组差异不显著,恢复6h后GOT活性极显著高于对照组（P<0.01）;谷丙转氨酶（Glutamic-pyruvic transaminase,GPT）在应激0、4h、12h和恢复到适温6h后的活性极显著高于对照组（P<0.01）;丙二醛（Malondialdehyde,MDA）含量在热应激2h、4h和12h时极显著高于对照组（P<0.01）,8h时显著高于应激前（P<0.05）,应激12h MDA含量达到最大值,恢复6h后MDA含量恢复至应激前水平（P<0.05）;补体3（Complement 3,C3）含量升高,在热应激12h时显著高于对照组（P<0.05）,恢复6h C3含量下降,与对照组差异不显著（P>0.05）。持续27℃热应激不同时间后,各实验组的细胞凋亡率都显著高于对照组（P<0.05）,且在处理4h时细胞凋亡率达到最高值（52.42%）,恢复19℃ 6h后细胞凋亡率显著降低（P<0.05）。研究表明,持续27℃热应激改变了机体非特异性免疫力,导致鱼体出现炎症,损伤细胞,恢复到适温后,鱼体各项机能逐渐恢复。研究结果可为深入研究齐口裂腹鱼高温适应调控机理提供基础数据,也为齐口裂腹鱼养殖、运输等过程中的温度控制提供科学依据。     

急性热应激对西伯利亚鲟HSP70 mRNA表达、血清皮质醇和非特异性免疫的影响

为研究西伯利亚鲟(Acipenser baerii)对急性热应激的抗逆机理, 将体质量为(155.4719.50) g的鱼从17.5 ℃迅速转至27.5 ℃水中, 在1h和3h取样测定HSP70 mRNA表达变化、血清皮质醇和非特异性免疫指标。结果显示: 急性热应激时鳃、脾和脑的HSP70 mRNA表达量升高, 具有组织特异性, 热应激1h时鳃的表达量升高最快(P0.05), 3h时保持1h时的表达水平; 脾和脑热应激1h时表达量变化不显著, 在1h至3h时升高较快, 并且脑组织的表达量升高最快(P0.05)。热应激1h时血清皮质醇(Cortisol)含量迅速升高(P0.05), 之后快速回落。脾脏巨噬细胞呼吸暴发在热应激1h时显著升高(P0.05), 3h时降低。血清补体C3在1h时略有升高, 3h时显著性降低(P0.05)。血清溶菌酶活性(LZM activity)先升高后降低差异不显著。血清超氧化物歧化酶(SOD)活力随热应激时间延长逐渐降低, 3h时显著降低(P0.05)。血清丙二醛(MDA)含量随热应激时间延长逐渐降低, 差异不显著。以上结果表明: 1h的短暂急性应激增强了西伯利亚鲟的非特异性免疫, 3h的应激使免疫力和抗氧化能力显著下降; 在热应激过程中, HSP70表达升高, 其中鳃组织最快, 起到应激保护作用, 提高了机体热耐受力。       

牛磺酸对HepG2细胞甘油三酯合成的影响研究

本文探讨牛磺酸对HepG2细胞甘油三酯合成的影响,为牛磺酸预防/改善机体高脂状态的深入研究提供参考。在DMEM培养基中添加0.05 mmol/L油酸建立高甘油三酯细胞模型,分别以终浓度为1、5、10、20 mmol/L的牛磺酸处理细胞24、48、72 h,测定细胞内甘油三酯水平;并检测5 mmol/L牛磺酸作用24 h后细胞内固醇调节元件结合蛋白1c(SREBP-1c)及脂肪合成相关酶乙酰辅酶A合成酶(AceCS)、乙酰辅酶A羧化酶(ACC)、脂肪酸合成酶(FAS)、长链酰基辅酶A合成酶1(ACSL1)的蛋白表达水平。1 mmol/L牛磺酸作用72 h,5和10 mmol/L牛磺酸作用24、48、72 h,20 mmol/L牛磺酸作用24和48 h均可使高脂HepG2细胞内甘油三酯水平显著下降(P0.05);5 mmol/L牛磺酸作用24 h,高脂HepG2细胞的SREBP-1c、FAS、ACC、AceCS1、ACSL1表达明显减少(P0.05),磷酸化ACC表达显著增加(P0.05)。结论:牛磺酸通过调控SREBP-1c及其下游靶基因而抑制高脂HepG2细胞脂肪酸/甘油三酯的合成。     

热应激和吡虫啉对大豆蚜hsp70和hsc70基因mRNA表达的影响

【目的】昆虫在高温或农药的胁迫下,通过高效表达热休克蛋白(HSP)等建立应激自我保护机制。本研究为从转录组水平上认识大豆蚜Aphis glycines在热应激和吡虫啉胁迫下hsp70和hsc70 mRNA表达分子机制,进而寻找自我保护应激反应中的薄弱环节,为大豆蚜的生物防治提供理论基础。【方法】采用同源克隆、RACE技术和实时荧光定量PCR等方法研究不同热激时间和热激后不同恢复时间及不同吡虫啉浓度对大豆蚜4龄若虫hsp70和hsc70的表达影响。【结果】37℃热激后,大豆蚜4龄若虫中hsp70表达量先上调,1 h时升至对照组的10.36倍（P<0.05）,然后逐渐下降。同样热激后恢复时间的长短对大豆蚜若蚜中hsp70的表达具有显著影响。热激处理后,大豆蚜若蚜中hsp70立即大量表达,表达量为对照组的8.78倍（P<0.05）,随后表达量下降至对照组水平,而hsc70的表达量并没有显著变化（P>0.05）。大豆蚜若蚜受吡虫啉的胁迫时,其hsp70和hsc70的表达量受吡虫啉的浓度及胁迫的时间的影响,呈现先升高后下降的趋势,具有明显的短期效应。【结论】吡虫啉诱导大豆蚜hsp70和hsc70表达量的上调;而热胁迫对hsp70和hsc70 mRNA具有不同的表达模式,高温可以诱导hsp70的表达,但对hsc70没有明显的诱导作用。     

黄斑蓝子鱼皮肤黏液对刺激隐核虫及一些病原菌的抑杀作用

黄斑蓝子鱼(Siganus oramin)具有天然抗刺激隐核虫(Cryptocaryon irritans)能力, 并从其血清中分离纯化了一种抗虫蛋白。以黄斑蓝子鱼皮肤黏液为对象, 研究了其对刺激隐核虫(C. irritans)、多子小瓜虫(Ichthyophthirius multifiliis)、布氏锥虫(Trypanosoma brucei brucei)及一些病原菌的杀灭和抑制效果。结果显示: 黄斑蓝子鱼黏液对刺激隐核虫、多子小瓜虫和布氏锥虫均具有明显的杀虫效果, 黏液蛋白对3种寄生虫的最低杀寄生虫浓度(Minimum Parasiticidal Concentration, MPC)分别为4.0、5.0和3.0 mg/mL。显微镜观察发现, 刺激隐核虫和多子小瓜虫的幼虫在经过黄斑蓝子鱼黏液作用后, 均出现纤毛脱落、虫体肿胀、外膜破裂和内容物泄漏等现象。黏液抑菌活性实验结果表明, 除大肠杆菌(Escherichia coli)外, 黄斑蓝子鱼皮肤黏液对金黄色葡萄球菌(Staphylococcus aureus)、霍乱弧菌(Vibrio cholerae)、海豚链球菌(Streptococcus iniae)、温和气单胞菌(Aeromonas sobria)、溶藻弧菌(Vibrio alginolyticus)、副溶血弧菌(Vibrio Parahaemolyticus)、星形诺卡氏菌(Nocadia asteroides)和美人鱼发光杆菌杀鱼亚种(Photobacterium damselae subsp.)皆有明显的抑菌效果。在最低抑菌浓度(Minimum Inhibitory Concentration, MIC)测定中, 黄斑蓝子鱼黏液对金黄色葡萄球菌、霍乱弧菌、海豚链球菌、溶藻弧菌、温和气单胞菌和副溶血弧菌的MIC 分别为0.16、0.16、0.08、0.63、0.63和0.63 mg/mL。黄斑蓝子鱼皮肤黏液对小麦赤霉菌(Gibberella saubinetii)和黑曲霉菌(Aspergillus niger)没有明显抑菌作用。       

日粮中不同水平维生素C对团头鲂幼鱼免疫力的影响

以酪蛋白和明胶为蛋白源,豆油为脂肪源配制团头鲂幼鱼基础饲料,制成维生素C水平为0.2、33.4、65.8、133.7、251.5和501.5 mg/kg 的6种等氮等能的试验饲料。对均重为（6.400.05）g的团头鲂幼鱼进行为期90d的饲养试验,以血清相关免疫指标、肝脏抗氧化指标、三种HSPs mRNA表达以及抗病原菌能力等指标为依据,研究Vc 对团头鲂幼鱼免疫力的影响。试验结果表明,与对照组相比,501.5 mg/kg Vc 试验组能显著提高血清补体3（C3）的浓度,133.7 mg/kg Vc 试验组能显著提高补体4（C4）的浓度;65.8、133.7和 251.5 mg/kg Vc 试验组能显著提高肝脏超氧化物歧化酶（SOD）的活性,各Vc 试验组均能显著提高肝脏抗超氧阴离子（ASAFR）的活性;133.7和251.7 mg/kg Vc 试验组能显著提高肝脏HSP60基因表达水平,251.5 mg/kg Vc 试验组能显著提高肝脏HSP70和HSP90基因表达水平（P0.05）;各Vc 试验组鱼的成活率在感染嗜水气单胞菌后12h、24h均显著高于对照组（P0.05）,其中以251.5 mg/kg Vc 试验组效果最佳。在日粮中添加Vc 对鱼体血清碱性磷酸酶（ALP）、总蛋白（TP）、白蛋白（Alb）、皮质醇（COR）以及肝脏丙二醛（MDA）的水平无显著影响（P0.05）。综上所述,在试验条件下,Vc 作为免疫刺激剂,其水平为133.7251.5 mg/kg时能有效地增强团头鲂幼鱼的免疫力。       

Effects of emodin and vitamin C on growth performance, biochemical parameters and two HSP70s mRNA expression of Wuchang bream (Megalobrama amblycephala Yih) under high temperature stress

In order to study the effects of dietary emodin, high-dose vitamin C (Vc) and their combination on growth of Wuchang bream (Megalobrama amblycephala Y.) and its resistance to high temperature stress, 1200 healthy Wuchang bream with initial body weight of 133.44 ± 2.11 g were randomly divided into four groups: a control group fed with basal diet (containing 50.3 mg/kg Vc) and three treated groups fed with basal diets supplemented with 60 mg/kg emodin, 700 mg/kg Vc, and the combination of 60 mg/kg emodin + 700 mg/kg Vc, respectively. After feeding for 60 days, the growth performance of Wuchang bream was measured. Then 25 fish per tank were exposed to heat stress of 34 °C. The biochemical parameters of blood and liver, and expression levels of liver two HSP70s mRNA before and after heat stress were determined and the cumulative mortality of each group under heat stress was counted. The results showed that before stress, compared with the control, the weight gain (WG) and specific growth rate (SGR), serum total protein (TP), lysozyme (LSZ), and alkaline phosphatase (ALP) levels, liver superoxide dismutase (SOD) activity and expression level of HSP70 mRNA significantly increased in emodin and Vc groups while feed conversion rate (FCR), serum cortisol (COR), triglyceride (TG) and liver malondialdehyde (MDA) contents decreased (P < 0.05); liver catalase (CAT) activity also significantly increased in emodin group (P < 0.05). Although serum TP, LSZ, and liver HSP70 mRNA levels significantly increased and liver MDA level decreased in combination group (P < 0.05), no synergism was observed. After heat stress, compared with the control, the serum TP, LSZ, ALP levels, liver SOD, CAT activities, and expression levels of HSC70 and HSP70 mRNAs increased in emodin and Vc groups in varying degrees and serum COR, glucose, glutamic-pyruvic transaminase (GPT), glutamic-oxaloacetic transaminase (GOT), TG and liver MDA levels decreased to some extent. Although these parameters had similar changing trend as above ones in combination group, it did not show any synergism either. Statistics showed that under heat stress, the cumulative mortalities of emodin and Vc groups, except at 6 h in emodin group, were significantly lower than that of the control (P < 0.05) while the difference between the combination and control groups was not significant (P > 0.05). Thus, the basal diet supplemented with 60 mg/kg emodin or 700 mg/kg Vc could promote the growth of Wuchang bream, reduce FCR, increase non-specific immunity of fish, antioxidant capacity, and two HSP70s mRNA expression levels, and enhance resistance to heat stress in fish. However, the combination of emodin and high-dose Vc showed no better effect.     

Maximal eccentric exercise induces a rapid accumulation of small heat shock proteins on myofibrils and a delayed HSP70 response in humans

In this study the stress protein response to unaccustomed maximal eccentric exercise in humans was investigated. Eleven healthy males performed 300 maximal eccentric actions with the quadriceps muscle. Biopsies from vastus lateralis were collected at 30 min and 4, 8, 24, 96, and 168 h after exercise. Cellular regulation and localization of heat shock protein (HSP) 27, alpha B-crystallin, and HSP70 were analyzed by immunohistochemistry, ELISA technique, and Western blotting. Additionally, mRNA levels of HSP27, alpha B-crystallin, and HSP70 were quantified by Northern blotting. After exercise (30 min), 81 +/- 8% of the myofibers showed strong HSP27 staining (P < 0.01) that gradually decreased during the following week. alpha B-Crystallin mimicked the changes observed in HSP27. After exercise (30 min), the ELISA analysis showed a 49 +/- 13% reduction of the HSP27 level in the cytosolic fraction (P < 0.01), whereas Western blotting revealed a 15-fold increase of the HSP27 level in the myofibrillar fraction (P < 0.01). The cytosolic HSP70 level increased to 203 +/- 37% of the control level 24 h after exercise (P < 0.05). After 4 days, myofibrillar-bound HSP70 had increased approximately 10-fold (P < 0.01) and was accompanied by strong staining on cross sections. mRNA levels of HSP27, alpha B-crystallin, and HSP70 were all elevated the first day after exercise (P < 0.01); HSP70 mRNA showed the largest increase (20-fold at 8 h). HSP27 and alpha B-crystallin seemed to respond immediately to maximal eccentric exercise by binding to cytoskeletal/myofibrillar proteins, probably to function as stabilizers of disrupted myofibrillar structures. Later, mRNA and total HSP protein levels, especially HSP70, increased, indicating that HSPs play a role in skeletal muscle recovery and remodeling/adaptation processes to high-force exercise.     

多囊卵巢综合征患者血清HSP70、IMA水平的变化及与性激素和氧化应激的相关性研究

目的:探讨多囊卵巢综合征(PCOS)患者血清热休克蛋白70(HSP70)、缺血修饰白蛋白(IMA)水平的变化及与性激素指标和氧化应激指标的相关性。方法:选择2017年6月~2018年6月华中科技大学同济医学院附属同济医院收治的未经治疗的初诊PCOS患者87例为PCOS组,另随机选择同期在本院进行体检的健康育龄妇女87例为对照组,比较两组血清HSP70、IMA、性激素指标、氧化应激指标,分析血清HSP70、IMA水平与性激素、氧化应激的相关性。结果:PCOS组患者血清卵泡刺激素(FSH)、促黄体生成素(LH)、睾酮(T)、8-异前列腺素F2α(8-isoPGF2α)、丙二醛(MDA)、HSP70、IMA水平显著高于对照组,差异有统计学意义(P<0.05);PCOS组患者血清超氧化物歧化酶(SOD)、谷胱甘肽过氧化酶(GSH-Px)水平低于对照组,差异有统计学意义(P<0.05);PCOS组血清雌二醇(E2)、泌乳素(PRL)水平与对照组比较差异无统计学意义(P>0.05)。PCOS患者血清HSP70、IMA水平与血清FSH、LH、T、8-iso PGF2α、MDA水平呈正相关关系,与SOD、GSH-Px水平呈负相关关系(P<0.05),与E2、PRL水平无显著相关性(P>0.05)。结论:血清HSP70、IMA水平在PCOS患者呈现异常升高,其水平改变与性激素及氧化应激水平密切相关,提示HSP70、IMA可能参与了PCOS的病理过程,临床检测HSP70、IMA的水平变化有可能为PCOS诊疗提供有效的预测作用。     

Hormonal regulation of potassium shifts during graded exhausting exercise

Serum potassium, aldosterone and insulin, and plasma adrenaline, noradrenaline and cyclic adenosine 3':5'-monophosphate (cAMP) concentrations were measured during graded exhausting exercise and during the following 30 min recovery period in six untrained young men. During exercise there was an increase in concentration of serum potassium (4.74 mmol.l-1, SEM 0.12 at the end of exercise vs 3.80 mmol.l-1, SEM 0.05 basal, P less than 0.001), plasma adrenaline (2.14 nmol.l-1, SEM 0.05 at the end of exercise vs 0.30 nmol.l-1, SEM 0.02 basal, P less than 0.001), plasma noradrenaline (1.10 nmol.l-1, SEM 0.64 at the end of exercise vs 1.50 nmol.l-1, SEM 0.05 basal, P less than 0.001), serum aldosterone (0.92 nmol.l-1, SEM 0.14 at the end of exercise vs 0.36 nmol.l-1, SEM 0.05 basal, P less than 0.01), and plasma cAMP (35.4 nmol.l-1, SEM 2.3 at the end of exercise vs 21.4 nmol.l-1, SEM 4.5 basal, P less than 0.05). While concentrations of serum potassium, plasma adrenaline and cAMP returned to their basal levels immediately after exercise, those of plasma noradrenaline and serum aldosterone remained elevated 30 min later (1.90 nmol.l-1, SEM 0.01, P less than 0.01; and 0.85 nmol.l-1, SEM 0.12, P less than 0.01, respectively). Serum insulin concentration did not change during exercise (6.47 mlU.l-1, SEM 0.58 at the end of exercise vs 5.47 mlU.l-1, SEM 0.41 basal, NS) but increased significantly (P less than 0.02) at the end of the recovery period (7.12 mlU.l-1, SEM 0.65).(ABSTRACT TRUNCATED AT 250 WORDS)     

Heat stress preconditioning does not protect renal epithelial Na(+),K(+),Cl(-) and Na(+),P(i) cotransporters from their modulation by severe heat stress

This study compares the effects of heat and osmotic stress on heat stress protein (HSP) production while examining the putative protective action of HSPs on modulation of Na(+),K(+),Cl(-) and Na(+),P(i) cotransporters in Madin-Darby canine kidney (MDCK) epithelial cells by severe heat stress (46 degrees C, 15 min). Preconditioning heat stress (43 degrees C, 20 min) followed by 4 h recovery at 37 degrees C led to a 35-fold increase of HSP70 mRNA expression measured by Northern blot analysis. The protein content of HSP70 and HSP27, assessed by Western blots, was augmented by 5- and 2-fold, respectively, after 6 h of recovery. In contrast to preconditioning heat stress, hyperosmotic stress (520 vs. 320 mosm) elevated HSP70 mRNA content only by 7-fold and did not significantly affect the protein content of HSP70 or HSP27. Neither cell survival, assessed as lactate dehydrogenase (LDH) release, nor the basal activities of the ion transporters and their modulation by protein kinase C, P(2)-purinoceptor and cell volume were altered by preconditioning heat stress. Severe heat stress increased extracellular LDH content from 3+/-2 to 23+/-5% and enhanced Na(+),K(+),Cl(-) and Na(+),P(i) cotransport activity by 2-3-fold. The volume- and protein kinase C-dependent regulation of these carriers was abolished by severe heat stress while regulation by P(2)-purinoceptors was preserved. Preconditioning heat stress diminished severe heat stress-induced LDH release to 11+/-4% but did not protect Na(+),K(+),Cl(-) and Na(+),P(i) cotransporters from activation by severe heat stress and did not prevent severe heat stress-induced inactivation of protein kinase C- and volume-dependent signaling pathways. These results show that in MDCK cells, preconditioning heat stress-induced HSPs are not involved in the regulation of Na(+),K(+),Cl(-) and Na(+),P(i) cotransporters and do not protect them from modulation by severe heat stress.     

Insulin modulates early-phase noradrenaline response to glucose ingestion in humans

To clarify the relationship between the early-phase insulin response and the early-phase noradrenaline (NA) response to glucose ingestion in humans, serum NA, adrenaline, immunoreactive insulin (IRI), C-peptide immunoreactivity, potassium, nonesterified fatty acid and plasma glucose levels were measured in 8 non-diabetics and 10 diabetics without autonomic disturbance after oral 75 g glucose load. Following results were obtained: 1) In non-diabetics, the maximal NA response was observed at 30 min after glucose ingestion, but in diabetics, mean serum NA levels remained unchanged. The effect of glucose ingestion on the NA response was significantly different between non-diabetics and diabetics by the repeated measurements analysis of variance (F ratio = 5.72, P less than 0.05). 2) In total group (n = 18), at early-phase after glucose ingestion (at 30 min), positive correlation was found between dIRI level and dNA level (r = 0.52, P less than 0.05), between dIRI level and %dNA level (r = 0.56, P less than 0.05), between dIRI/dglucose ratio (insulinogenic index) and dNA level (r = 0.70, P less than 0.01). 3) In four diabetics, NA responses to glucose ingestion were studied again after mild energy restriction for 2 wk. In three of them, both early-phase IRI response and early-phase NA response to glucose ingestion improved after diet therapy, but in the remainder, early-phase NA response to glucose ingestion remained unchanged in accordance with sustained impaired early-phase insulin response to glucose ingestion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Aging effects on the habitual expression of HSP70 mRNA in the hippocampus of rats

Heat shock proteins are induced by stressful stimuli and have been shown to protect cells and organs from such stresses both in vitro and in vivo. This study examined the regulation of HSP70 mRNA expression and detected the effect of aging on RNA expression in hippocampus of rats. The stress models were built by using forced-swimming in 25 degrees C and 4 degrees C water, respectively. Two groups of male rats, 2-month-old and 16-month-old, respectively, were randomly divided into three subgroups: acute stress (AS) model, chronic habituation stress (CHS) model and chronic dishabituation stress (CDS) model. Observation of exploratory behavior in an open-field (OF) test indicated stress levels. The expression of HSP70 mRNA in hippocampus was measured by RT-PCR after 0, 30, 60, 180, and 360 min of stress, respectively. Results showed that the number of quadrant crossing in both aged CHS and young CHS groups decreased gradually with the process of stress, reflecting an adaptation to the stress condition. Repeated swimming in warm water resulted in habitual expression of HSP70 mRNA in both young and aged CHS group, indicating an adaptation to the stress. The RNA expression of young CHS group was significantly stronger than that of the aged CHS group at 30, 60, 180, and 360 min after stress (P < 0.05). Meanwhile, in an intensive stress level in which the rats swam in 4 degrees C water, a high expression level of HSP70 mRNA was achieved in CDS groups, producing a dishabituation that proved the habitual expression from the other side. These results showed that senescence dramatically affected both exploratory behavior and HSP70 mRNA expression in rats' hippocampus. The results also suggested that chronic stress could lead to the habituational expression of HSP70 mRNA, but high intensive stress could reverse the habituational state and lead to the dishabituational expression. Moreover, the duration of stimuli is one of the important factors that affect the level of HSP70 mRNA expression.     

Effects of active and passive hyperthermia on heat shock protein 70 (HSP70)

Summary. The purpose of this study was to delineate the effects of hyperthermia and physical exercise on the heat shock protein 70 (HSP70) response in circulating peripheral blood mononuclear cells (PBMCs). Six healthy, young (age: 24 ± 3 yrs), moderately trained males (VO_2max: 48.9 ± 2.7 ml · kg · min⁻¹) undertook two experimental trials in a randomised fashion in which the core temperature (T _c) was increased and then maintained at 39 °C during a 90 min bout by either active (AH) or passive (PH) means. AH involved subjects cycling at 90% of their lactate threshold in attire designed to impede heat loss mechanisms. In the PH trial, subjects were immersed up to the neck in a hot bath (40.2 ± 0.4 °C), once the critical T _c was achieved, intermittent cycling and water immersions were prescribed for the AH and PH conditions, respectively, to maintain the T _c at 39 °C. HSP70 was measured intracellularly pre, post and 4 h after trials, from circulating PBMCs using an ELISA technique. T _c reached 39 °C quicker in PH than during AH trials (PH: 21 ± 4 min vs. AH: 39 ± 6 min; P < 0.01), thereafter T _c was maintained around 39 °C (PH: 39.1 ± 0.2 °C; AH: 38.8 ± 0.3 °C; P > 0.05). AH induced a marked leukocytosis in all sub-sets (P < 0.05). PH generated significant monocytosis and granulocytosis (P < 0.05), without changes in lymphocyte counts (P > 0.05). There were no significant increases in intracellular HSP70 at 0 h (AH: Δ − 21.1 ± 44.8; PH: Δ + 12.5 ± 32.4 ng/mg TP/10³/μl PBMCs; P > 0.05) and 4 h (AH: Δ − 30.0 ± 40.1; PH: Δ + 36.3 ± 70.4 ng/mg TP/10³/μl PBMCs; P > 0.05) post active and passive heating. Peak HSP70 expressed as a fold-change from rest was also not increased by AH (1.1 ± 0.9; P > 0.05) or PH (3.2 ± 4.8; P > 0.05). There were no significant differences between the AH and PH trials at any time-point, and the HSP70 response appeared to be individual specific. These results did not allow us to delineate the effects of hyperthermia and other exercise associated stressors on the heat shock response and therefore further work is warranted. Authors’ address: Ric Lovell, Department of Sport, Health and Exercise Science, University of Hull, Hull HU6 7RX, U.K.