Thermal stress-induced HSP70 mediates protection against intrapancreatic trypsinogen activation and acute pancreatitis in rats.

BACKGROUND & AIMS: Prior thermal stress induces heat shock protein 70 (HSP70) expression in the pancreas and protects against secretagogue-induced pancreatitis, but it is not clear that this thermal stress-induced protection is actually mediated by HSP70 since thermal stress may have other, non-HSP related, effects. METHODS: In the present study, we have administered antisense (AS) oligonucleotides, which prevent pancreatic expression of HSP70 to rats, in vivo, to evaluate this issue. In a separate series of experiments, designed to examine the role of pancreatitis-induced HSP70 expression in modulating the severity of pancreatitis, rats not subjected to prior thermal stress were given AS-HSP70 before cerulein administration, and trypsinogen activation as well as the severity of pancreatitis were evaluated. RESULTS: Hyperthermia induced HSP70 expression, prevented intrapancreatic trypsinogen activation, and protected against cerulein-induced pancreatitis. Administration of AS-HSP70 but not sense-HSP70 reduced the thermal stress-induced HSP70 expression, restored the ability of supramaximal cerulein stimulation to cause intrapancreatic trypsinogen activation, and abolished the protective effect of prior thermal stress against pancreatitis. In non-thermally stressed animals, pretreatment with AS-HSP70 before the induction of pancreatitis exacerbated all the parameters associated with pancreatitis. CONCLUSIONS: These findings lead us to conclude that HSP70 induction, rather than some other thermal stress-related phenomenon, mediates the thermal stress-induced protection against pancreatitis and that it protects against pancreatitis by preventing intrapancreatic activation of trypsinogen. The worsening of pancreatitis, which occurs when non-thermally stressed animals are given AS-HSP70 before cerulein, suggests that cerulein-induced HSP70 expression in nontreated animals acts to limit the severity of pancreatitis.     

Increased heat shock protein 70 expression attenuates pancreatic fibrosis induced by dibutyltin dichloride

Abstract

Objectives: Heat shock protein (HSP) 70 performs a chaperoning function and protects cells against injury. Although the effect of HSPs against acute inflammatory change has been proven, the relationship between HSP70 and chronic pancreatitis remains unclear. This study aimed to investigate the protective effect of increased HSP70 expression induced by thermal stress against pancreatic fibrosis in experimental chronic pancreatitis.

Materials and Methods: Two experiments to evaluate pancreatic HSP70 expression induced by thermal stress and determine the effect of increased HSP70 expression against pancreatic fibrosis were performed. To investigate HSP70 expression, rats were immersed in a warm bath and sequentially killed, and pancreatic HSP70 expression was measured. To study the effect of increased HSP70 expression, pancreatic fibrosis was induced by intravenous injection of dibutyltin dichloride (DBTC) and analyzed under repeated thermal stress. The severity of pancreatic fibrosis was measured.

Results: Thermal stress significantly increased HSP70 expression in the pancreas. HSP70 expression peaked at 6–12?h after warm bathing, and the increased HSP70 expression was associated with the attenuation of pancreatic fibrosis. Although pancreatic fibrosis was induced by DBTC injection, HSP70 expression induced by repeated thermal stress diminished the severity of atrophy and fibrosis. On western blot analysis, collagen type 1 expression was diminished in the increased HSP70 expression group, but not α-smooth muscle actin expression.

Conclusions: Thermal stress could increase pancreatic HSP70 expression, and induced HSP70 expression showed a protective effect against pancreatic fibrosis. Modulation of HSP70 expression could be a potential therapeutic target in the treatment of chronic pancreatitis.     

Arginine induced acute pancreatitis alters the actin cytoskeleton and increases heat shock protein expression in rat pancreatic acinar cells

Arginine induced acute pancreatitis was evaluated as a novel and distinct form of experimental pancreatitis with particular attention to the actin cytoskeleton and expression of heat shock or stress proteins. Arginine induced a dose related necrotising pancreatitis in rats, as shown by histological evaluation, and an increase in serum amylase. Severe pancreatitis induced by 4.5 g/kg arginine was accompanied by dramatic changes in the actin cytoskeleton, as visualised with rhodamine phallodin. Intermediate filaments were also disrupted, as visualised by cytokeratin 8/18 immunocytochemistry. Arginine pancreatitis was accompanied by a stress response with a large increase in the small heat shock protein HSP27, as well as HSP70, peaking at 24 hours and localised to acinar cells. There was a lower increase in HSP60 and HSP90 and no effect on GRP78. HSP27 was also shifted to phosphorylated forms during pancreatitis. A lower dose of arginine (3.0 g/kg) induced less pancreatitis but a larger increase in HSP70 and HSP27 expression and phosphorylation of HSP27. Thus HSP expression can be overwhelmed by severe damage. The present work in conjunction with earlier work on caerulein induced pancreatitis indicates that changes in the actin cytoskeleton are an early component in experimental pancreatitis.     

Water immersion stress induces heat shock protein 60 expression and protects against pancreatitis in rats

BACKGROUND & AIMS: Heat shock proteins (Hsps), induced by cell stress, are known to protect against cellular injury. Recent studies have indicated that Hsp60 expression, induced by exposure to water immersion stress, protects against pancreatitis induced by administration of supramaximal doses of cerulein in rats. However, the mechanisms responsible for this protection are not known. Methods: Rats were water-immersed for 3-12 hours. Pancreatitis was induced by cerulein administration. RESULTS: The results confirm that prior induction of Hsp60 expression by water-immersion stress significantly ameliorates the severity of cerulein-induced pancreatitis as judged by the markedly reduced degree of hyperamylasemia, pancreatic edema, and acinar cell necrosis. Water immersion also prevents the subcellular redistribution of cathepsin B from a lysosome-enriched fraction to a heavier, zymogen granule-enriched fraction that is known to occur in this model of pancreatitis. Intra-acinar cell activation of trypsinogen that occurs shortly after exposure to a supramaximally stimulating dose of cerulein both in vivo and in vitro is prevented by prior water-immersion stress and Hsp60 expression. The protection against pancreatitis that follows water-immersion stress is not caused by alterations of cholecystokinin receptors, because water immersion does not alter the typical biphasic amylase secretory response to stimulation with cerulein. CONCLUSIONS: Water-immersion stress induces Hsp60 expression, ameliorates cerulein-induced pancreatitis, and prevents intra-acinar cell activation of trypsinogen. We suggest that Hsp60 protects against cerulein-induced pancreatitis by preventing trypsinogen activation within acinar cells.     

Hyperthermia, inducing pancreatic heat-shock proteins, fails to prevent cerulein-induced stress kinase activation.

The dually phosphorylated c-jun kinase and p38 mitogen-activated protein (MAP) kinase, also termed stress kinases, are members of the MAP kinase family. They are activated early during cerulein pancreatitis induction and have been proposed as regulators during pancreatitis development by us and others. We recently showed that hyperthermia preconditioning induces expression of pancreatic heat-shock proteins (HSP) and protects against cerulein pancreatitis. Because it was further reported that HSP70 can prevent activation of stress kinases in lymphoid tumor cells, we investigated whether hyperthermia preconditioning might reduce hyperstimulation-mediated activation of pancreatic stress kinases. Pancreatic HSP expression was induced by whole-body hyperthermia preconditioning. Without prior HSP induction, cerulein led to a rapid and dose-dependent increase in serum lipase and amylase levels, pancreatic wet weight through edema formation, and activation of pancreatic MAP kinases. Hyperthermia preconditioning, although strongly inducing HSP70 and almost completely preventing edema formation, as well as the increase of serum amylase and lipase, did not reduce cerulein-mediated stress kinase activation. This indicates that in the pancreas, cerulein can strongly activate MAP kinases even when pancreatitis development is greatly inhibited, and that pancreatic HSPs do not inhibit activation of pancreatic stress kinases in vivo.     

Protease-activated receptor-2 protects against pancreatitis by stimulating exocrine secretion

BACKGROUND: Protease-activated receptor-2 (PAR-2) is present in the pancreas, where it has been shown to play a protective role during pancreatitis. However, the mechanism by which it protects against pancreatitis still remains to be elucidated. Acute pancreatitis is associated with premature zymogen activation and a blockage in digestive enzyme secretion. AIM: To examine the effects of PAR-2 activation on the severity of pancreatitis, and to determine whether its protective effects are mediated by affecting either premature activation or secretory blockage, or both. RESULTS: The results confirmed that PAR-2 -/- mice have more severe pancreatitis than wild-type mice. Interestingly, intrapancreatic trypsin levels in the PAR-2 knockouts remained high after 6 h of pancreatitis, whereas they reverted to normal in the wild types. During pancreatitis, PAR-2 mRNA levels were upregulated in wild-type mice in response to supramaximal caerulein administration. Further, after a single injection of supramaximal caerulein, PAR-2 mRNA levels were also elevated, reaching a peak at 3 h. Stimulating PAR-2 with trypsin or the PAR-2-activating peptide, serine-leucine-isoleucine-glycine-arginine-leucine (SLIGRL), induced significantly more secretion from the acini of these caerulein-sensitised mice compared with the controls. PAR-2 activation also reversed the inhibition of secretion observed in both the caerulein and arginine models. CONCLUSIONS: Trypsin released during the early stages of pancreatitis activates PAR-2 receptors on the acinar cells and stimulates secretion from these cells. Thus, PAR-2 activation may decrease pancreatic injury and limit the severity of pancreatitis by allowing extracellular trypsin to act as a secretagogue.     

Pancreatic and bile duct obstruction exacerbates rat caerulein-induced pancreatitis: a new experimental model of acute hemorrhagic pancreatitis

Background Pancreatic duct obstruction induces edematous but not hemorrhagic pancreatitis even when combined with maximal secretory stimulation. The aim of the present study was to test the hypothesis that pancreatic and bile duct obstruction exacerbates edematous pancreatitis induced by supramaximal secretory stimulation by caerulein. Methods In in vivo studies using rats, biliopancreatic duct ligation was combined with supramaximal stimulation of caerulein, and pancreatic histology, serum amylase level, pancreatic edema, and intrapancreatic trypsin activation were evaluated. In in vitro studies, the pancreatic acini were isolated from the rats with biliopancreatic duct ligation, and amylase secretion, intracellular trypsin activation, and acinar cell fragility were evaluated. Results Biliopancreatic duct ligation exacerbated caerulein-induced pancreatitis from edematous to hemorrhagic only when the obstruction preceded caerulein administration. The amylase secretion from the acini was inhibited, and intracellular trypsin activation and the acinar cell fragility on the supramaximal stimulation with cholecystokinin in vitro were enhanced by the preceding in vivo biliopancreatic duct obstruction. Conclusions Preceding biliopancreatic duct obstruction exacerbates caerulein-induced pancreatitis. Enhancement of intracellular trypsin activation is possibly involved in this mechanism.     

Hyperthermia induces multiple pancreatic heat shock proteins and protects against subsequent arginine-induced acute pancreatitis in rats

Heat shock proteins (HSPs) which are induced by stress can provide protection against subsequent cellular damage. Whole body hyperthermia in rats leading to induction of HSP70 has been shown to protect against subsequent caerulein-induced acute pancreatitis. We studied the effect of hyperthermia on pancreatic HSP expression and found a significant increase in HSP70 (26.0-fold) and HPS27 (6.0-fold) but no change in HSP60, HSP90 or GRP78. Hyperthermia conferred significant protection against subsequent arginine-induced acute pancreatitis. More specifically, the degradation and disorganization of the actin cytoskeleton, an important early component of acute pancreatitis, was prevented. These results generalize previous work on caerulein-induced pancreatitis to another model of experimental pancreatitis, arginine-induced pancreatitis, and suggest that multiple HSPs may be involved in the cytoprotective effect in rat pancreas.     

Role of platelet activating factor in pathogenesis of acute pancreatitis in rats.

The importance of platelet activating factor in acute pancreatitis was examined by determining the tissue content of endogenous platelet activating factor and the protective effects of TCV-309, a highly selective platelet activating factor blocker, against caerulein induced pancreatitis in rats. Infusion of caerulein (10 micrograms/kg/h) for five hours resulted in about 70% increase in pancreatic weight, 22% rise in protein content, 50% reduction in tissue blood flow, nine fold increase in tissue level of platelet activating factor and 165% rise in plasma amylase as well as histological evidence of acute pancreatitis. Such infusion of caerulein in chronic pancreatic fistula rats caused a marked increase in protein output from basal secretion of 10 mg/30 minutes to 40 mg/30 minutes in the first hour of infusion followed by a decline in protein output to 15-20 mg/30 minutes in the following hours of the experiment. Exogenous platelet activating factor (50 micrograms/kg) injected ip produced similar alterations in weight, protein content, blood flow, and histology of the pancreas but the increment in serum amylase was significantly smaller and pancreatic secretion was reduced below the basal level. TCV-309 (50 micrograms/kg) given ip before caerulein or platelet activating factor administration significantly reduced the biochemical and morphological alterations caused by caerulein and abolished those induced by exogenous platelet activating factor. These results indicate that platelet activating factor plays an important role in the pathogenesis of acute pancreatitis probably by reducing the blood flow and increasing vascular permeability in the pancreas.     

p38 MAPK inhibition alleviates experimental acute pancreatitis in mice

BACKGROUND: The mitogen-activated protein kinases (MAPKs) signaling pathway is involved in inflammatory process. However,the mechanism is not clear. The present study was to investigate the role of p38 MAPK in acute pancreatitis in mice.METHODS: Mice were divided into 4 groups: saline control; acute pancreatitis induced with repeated injections of cerulein; control plus p38 MAPK inhibitor SB203580; and acute pancreatitis plus SB203580. The pancreatic histology, pancreatic enzymes, cytokines, myeloperoxidase activity, p38 MAPK and heat shock protein (HSP) 60 and 70 were evaluated.RESULTS: Repeated injections of cerulein resulted in acute pancreatitis in mice, accompanying with the activation of p38 MAPK and overexpression of HSP60 and HSP70 in the pancreatic tissues. Treatment with SB203580 significantly inhibited the activation of p38 MAPK, and furthermore, inhibited the expression of HSP60 and HSP70 in the pancreas, the inflammatory cytokines in the serum, and myeloperoxidase activity in the lung.CONCLUSION: The p38 MAPK signaling pathway is involved in the regulation of inflammatory response and the expression of HSP60 and HSP70 in acute pancreatitis.     

Suppression of transforming growth factor beta signalling aborts caerulein induced pancreatitis and eliminates restricted stimulation at high caerulein concentrations

BACKGROUND: Transforming growth factors betas (TGF-betas) are implicated in pancreatic tissue repair but their role in acute pancreatitis is not known. To determine whether endogenous TGF-betas modulate the course of caerulein induced acute pancreatitis, caerulein was administered to wild-type (FVB-/-) and transgenic mice that are heterozygous (FVB+/-) for expression of a dominant negative type II TGF-beta receptor. METHODS: After 7 hourly supramaximal injections of caerulein, the pancreas was evaluated histologically and serum was assayed for amylase and lipase levels. Next, the effects of caerulein on amylase secretion were determined in mouse pancreatic acini, and cholecystokinin (CCK) receptor expression was assessed. RESULTS: The normal mouse pancreas was devoid of inflammatory cells whereas the pancreas from transgenic mice contained lymphocytic infiltrates. Caerulein injection in wild-type mice resulted in 6- and 36-fold increases in serum amylase and lipase levels, respectively, increased serum trypsinogen activation peptide (TAP) levels, gross oedema and a marked inflammatory response in the pancreas that consisted mainly of neutrophils and macrophages. By contrast, FVB+/- mice exhibited minimal alterations in response to caerulein with attenuated neutrophil-macrophage infiltrates. Moreover, acini from FVB+/- mice did not exhibit restricted stimulation at high caerulein concentrations, even though CCK receptor mRNA levels were not decreased. CONCLUSION: Our findings indicate that a functional TGF-beta signalling pathway may be required for caerulein to induce acute pancreatitis and for the CCK receptor to induce acinar cell damage at high ligand concentrations. Our results also support the concept that restricted stimulation at high caerulein concentrations contributes to the ability of caerulein to induce acute pancreatitis.     

Induction of HSP72 by sodium arsenite fails to protect against cholecystokinin-octapeptide-induced acute pancreatitis in rats

A number of investigators have demonstrated that the preinduction of heat-shock protein (HSP) expression (particularly HSP60 and HSP72) by hyper- or hypothermia may have a protective effect against cerulein-induced acute pancreatitis. The aim of the present study was to induce HSPs in the pancreas and lungs by thermal (hot-water immersion, HWI) and nonthermal methods (injection of sodium arsenite intraperitoneally) and to investigate the potential effects of HSP preinduction on cholecystokinin-octapeptide (CCK) induced acute pancreatitis and pancreatitis-associated lung injury in rats. The dose–response and time–effect curves observed following HWI and sodium arsenite treatments were evaluated. Animals were injected with 3 × 75 g/kg CCK subcutaneously at intervals of 2 hr at the peak level of HSP synthesis, as determined by Western blot analysis. The rats were killed by exsanguination through the abdominal aorta 2 or 6 hr after the last CCK injection. HWI and the injection of sodium arsenite significantly elevated the expression of HSP72 in the pancreas and lungs, whereas they did not influence the levels of HSP60. Overall, HWI pretreatment had a protective effect against CCK-induced pancreatitis and pancreatitis-associated lung injury. In contrast, the nonthermal preinduction of HSP72 by sodium arsenite did not result in any beneficial effects on the measured parameters of the disease. The findings suggest that the preinduction of HSP72 is not sufficient to protect against CCK-induced acute pancreatitis and pancreatitis-associated lung injury or that the beneficial effect of hyperthermia may not be exclusively related to HSP72 expression.     

Potentiation of baroreceptor reflex response by heat shock protein 70 in nucleus tractus solitarii confers cardiovascular protection during heatstroke

BACKGROUND: Whereas hypotension and bradycardia seen during the onset of heatstroke may be protected by prior induction of heat shock protein 70 (HSP70) in the brain, the underlying mechanism is not fully understood. We evaluated the hypothesis that HSP70 may confer cardiovascular protection during heatstroke by potentiating the baroreceptor reflex (BRR) control of peripheral hemodynamic performance. METHODS AND RESULTS: Adult male Sprague-Dawley rats subjected to a brief hyperthermic heat shock (HS; 42 degrees C for 15 minutes) induced discernible expression of HSP70 in the bilateral nucleus tractus solitarii (NTS), the terminal site in the brain stem for primary baroreceptor afferents. This HSP70 expression was detected at 8 hours, peaked at 24 hours, and returned to baseline by 48 hours after HS. Brief hyperthermia also significantly potentiated the BRR response in a temporal profile that correlated positively with changes in HSP70 expression at the NTS. Prior HS also appreciably alleviated hyperthermia, severe hypotension, and bradycardia manifested during the onset of heatstroke (45 degrees C for 60 minutes) elicited 24 hours later. Microinjection bilaterally of anti-HSP70 antiserum (1:20) into the NTS or denervation of the sinoaortic baroreceptor afferents significantly reversed the enhancement of BRR response and cardiovascular protection during heatstroke induced by prior HS. CONCLUSIONS: These results suggest that HS-induced expression of HSP70 in the NTS may alleviate severe hypotension and bradycardia exhibited during the onset of heatstroke by potentiating both the sensitivity and capacity of BRR response.     

Heat Shock Response is Associated with Protection Against Acute Interstitial Pancreatitis in Rats

We recently reported that hyperthermia induces pancreatic expression of heat shock proteins (HSPs), particularly HSP70 isoforms, and protects against cerulein pancreatitis. We have now studied whether a double hyperthermia amplifies these effects and whether hyperthermia also protects against dibutyltin dichloride (DBTC)-induced pancreatitis. A further aim was to examine whether hyperthermia induces changes in transforming growth factor-₁ (TGF-₁). Following pretreatment without or with a single or double hyperthermia, pancreatitis was induced by application of cerulein or DBTC. Pancreatic HSP and TGF-₁ expression were studied by immunoblotting. Pancreas injury was assessed by light microscopy and serum pancreatic enzyme activity. Hyperthermia as well as DBTC induced HSP72, whereas cerulein did not. A double hyperthermia led to a further increase in HSP72 compared to a single heat stress. In both models, hyperthermia significantly reduced pancreatic injury. Although a double hyperthermia slightly decreased the severity of cerulein pancreatitis compared to a single heat treatment, an improved pancreas protection against DBTC cytotoxicity was not achieved. We also found that hyperthermia induces the expression of TGF-₁. In conclusion, hyperthermia preconditioning exerts protective effects against two pathophysiologically different types of pancreatitis by a mechanism that involves the up-regulation of HSP70 isoforms as well as TGF-₁.     

Heat shock proteins and autophagy in rats with cerulein-induced acute pancreatitis

Background/Aims

Heat shock proteins (HSPs) protect rats from cerulein-induced acute pancreatitis (AP) by preventing the subcellular redistribution of cathepsin B and the activation of trypsinogen. Autophagy plays a critical role in the secretion of digestive enzymes and triggering of cerulein-induced AP via the colocalization of trypsinogen and lysosomes. Therefore, using a rat cerulein-induced AP model, we investigated whether HSPs prevent AP by regulating autophagy.

Methods

Twelve hours after fed standard laboratory chow and water, the experimental groups (cerulein, water-immersion [WI]-cerulein and heat-shock [HS]-cerulein) and the control groups (control, WI, and HS) received one intraperitoneal injection of cerulein (50 µg/kg) or saline, respectively. All of the rats were sacrificed at 6 hours after injection. The severity of the AP was assessed based on the serum amylase level and the histological and electron microscopy findings. Western blotting was also performed for HSP60/70 and LC3B-II.

Results

WI and HS induced HSP60 and HSP70, respectively. The induced HSP60/70 effectively prevented the development of cerulein-induced AP. Autophagy developed in the rats with cerulein-induced AP and was documented by the expression of LC3-II and electron microscopy findings. The WI-stressed rats and HS-treated rats did not develop cerulein-induced autophagy.

Conclusions

HSPs exert protective effects against cerulein-induced AP in rats by inhibiting autophagy.     

Necrostatin-1对雨蛙肽诱导的小鼠急性胰腺炎的保护作用

目的观察Necrostatin-1(Nec-1)对雨蛙肽诱导的小鼠急性胰腺炎(AP)的影响。方法 C57BL/6小鼠予以50μg/kg的雨蛙肽腹腔注射7次,间隔1 h,建立AP模型。于第1次雨蛙肽注射后3 h、6 h、9 h和12 h,取出胰腺组织,HE染色。Western blot检测RIP1和RIP3蛋白的表达;C57BL/6小鼠随机分为:Control组、Vehicle组、Nec-1组和Nec-1i组,予以50μg/kg的雨蛙肽腹腔注射10次,间隔1 h,第1次雨蛙肽注射2 h前,腹腔注射Nec-1(1 mg/kg,每6 h 1次)、Nec-1i或等体积溶剂和空白对照。于第1次雨蛙肽注射后12 h、18 h和24 h,收集血清和胰腺组织。检测血清淀粉酶和脂肪酶。HE染色评估胰腺损伤程度。Real-time RT-PCR检测胰腺组织IL-1β和TNF-αmRNA的表达。结果 RIP1和RIP3蛋白在雨蛙肽诱导的AP中逐渐升高,且与胰腺腺泡细胞的坏死呈正相关;应用Nec-1后,与Vehicle组和Nec-1i组比较,于12 h、18 h和24 h,小鼠血清淀粉酶和脂肪酶水平明显降低,胰腺组织病理评分也明显减少,同时胰腺组织中IL-1β和TNF-αmRNA的水平也明显降低。结论 Nec-1对实验性胰腺炎具有明显的保护作用;程序性坏死可能促进了急性胰腺炎的损伤。     

Heat shock does not induce tolerance to hyperoxia

Thermal stress is associated with the induction of a specific set of proteins called heat shock proteins and with the induction of thermal tolerance. Heat stress has been shown to be capable of inducing at least partial tolerance to other stresses, including some oxidant stresses. Furthermore, these oxidant stresses are reported to be inducers of heat shock proteins. We hypothesized that hyperoxic stress would induce heat shock proteins and that factors induced by thermal stress, including heat shock proteins, would offer at least partial protection from hyperoxic exposure. We were particularly interested in a level of protection that would be relevant to clinical situations. Lung fibroblasts and live animals were exposed to thermal stress and/or hyperoxic stress and examined for induction of HSP70 (the most conserved of the heat shock proteins) and for induced tolerance as determined by the ability of cells to metabolize 3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and by comparison of lung wet to dry weight ratios in live animals. Each stress induced tolerance to itself, but there was no evidence of heat stress inducing tolerance to hyperoxic stress. Furthermore, there was only minimal induction of HSP70 mRNA by hyperoxic exposure. We conclude that some overlap of mechanisms of induced tolerance by hyperoxic and thermal stress exists, but that differences far outweigh similarities. Offprint requests to: H. C. Jacobs     

热休克蛋白70对过氧化氢所致乳鼠心肌细胞核仁损伤的保护作用

为探讨氧化应激时体外培养的新生Wistar大鼠心肌细胞核仁损伤以及热休克蛋白70对损伤核仁的保护作用。用0.5mmol/L过氧化氢处理原代培养的心肌细胞0,30,60min，采用甲苯胺兰染色核仁及电镜技术观察核仁结构的改变；并通过热休克预处理及反义技术诱导或阻断热休克蛋白70的表达，观察其对核仁损伤的保护作用。结果发现，光镜下过氧化氢损伤组心肌细胞核仁染色颗粒数增多，电镜下核仁结构松散，核仁组份分离。热休克预处理导致心肌细胞中热休克蛋白70表达明显增加，并使过氧化氢缺致心肌细胞核仁损伤明显减轻，免疫组织化学显示过氧化氢可引起热休克蛋白70从胞浆到胞核，再到核仁的移位，热休克蛋白70反义寡核苷酸很大程度上能阻断热休克预处理对心肌细胞核仁损伤的保护作用。结果提示，过氧化氢可导致体外培养的新生大鼠心肌细胞核仁结构损伤，热休克蛋白70高表达及其向核仁的移位对上述损伤具有明显保护作用。