Preinduction of HSP70 promotes hypoxic tolerance and facilitates acclimatization to acute hypobaric hypoxia in mouse brain

It has been shown that induction of HSP70 by administration of geranylgeranylacetone (GGA) leads to protection against ischemia/reperfusion injury. The present study was performed to determine the effect of GGA on the survival of mice and on brain damage under acute hypobaric hypoxia. The data showed that the mice injected with GGA survived significantly longer than control animals (survival time of 9.55 ± 3.12 min, n = 16 vs. controls at 4.28 ± 4.29 min, n = 15, P < 0.005). Accordingly, the cellular necrosis or degeneration of the hippocampus and the cortex induced by sublethal hypoxia for 6 h could be attenuated by preinjection with GGA, especially in the CA2 and CA3 regions of the hippocampus. In addition, the activity of nitric oxide synthase (NOS) of the hippocampus and the cortex was increased after exposure to sublethal hypoxia for 6 h but could be inhibited by the preinjection of GGA. Furthermore, the expression of HSP70 was significantly increased at 1 h after GGA injection. These results suggest that administration of GGA improved survival rate and prevented acute hypoxic damage to the brain and that the underlying mechanism involved induction of HSP70 and inhibition of NOS activity.     

The protective role of 5-HMF against hypoxic injury

In an attempt to find new types of anti-hypoxic agents from herbs, we identified 5-hydroxymethyl-2-furfural (5-HMF) as a natural agent that fulfills the criterion. 5-HMF, the final product of carbohydrate metabolism, has favorable biological effects such as anti-oxidant activity and inhibiting sickling of red blood cells. The role of 5-HMF in hypoxia, however, is not yet. Our pilot results showed that pretreatment with 5-HMF markedly increased both the survival time and the survival rate of mice under hypoxic stress. The present study was aimed to further investigate the protective role of 5-HMF and the underlying mechanisms in hypoxic injury using ECV304 cells as an in vitro model. ECV304 cells pretreated with or without 5-HMF for 1 h were exposed to hypoxic condition (0.3% O₂) for 24 h and then cell apoptosis, necrosis, the changes of mitochondrial membrane potential (MMP) and the expressions of phosphorylation- extracellular signal-regulated kinase (p-ERK) were investigated. Pretreatment with 5-HMF markedly attenuated hypoxia-induced cell necrosis and apoptosis at late stage (p < 0.01). Furthermore, pretreatment with 5-HMF rescued both the decline of the MMP and the increase of p-ERK protein under hypoxia. In a word, these results indicated that 5-HMF had protective effects against hypoxic injury in ECV304 cells, and its effects on MMP and p-ERK may be involved in the mechanism.     

Comparisons of serum testosterone and corticosterone between exercise training during normoxia and hypobaric hypoxia in rats

The purpose of this study was to compare the effects of continuous and intermittent exercise training on serum testosterone [T] and corticosterone concentrations [Cort] during normoxia and hypobaric hypoxia. Male rats swam with loads of 3% (normoxia) or 2.25% (462 mmHg) body mass for 60 min in the continuous training groups, and 15 min separated by a 7-min rest  × 4, with 60-min total exercise duration in the intermittent training groups, 5␣days · week⁻¹ for 6 weeks. Serum [T] were measured at␣rest and following exercise after 6 weeks of training. Serum [Cort] were measured immediately after an acute period of exercise or after 6 weeks of training at rest and following exercise. Continuous exercise induced decreases in [T] under both conditions. Intermittent exercise showed a tendency to increase [T] during normoxia, but caused a suppression during hypobaric hypoxia. The [Cort] was elevated by a similar margin after an acute period of exercise during both conditions. After 6 weeks of training, however, [Cort] increased slightly after exercise during normoxia. A lower resting [Cort], which was increased after exercise, was found in the training groups during hypoxia. No relevant relationship was found between the behaviours of [T] and [Cort] after exercise during either conditions. Accepted: 20 April 1998     

The effect of preceding mild hypoxia on the alteration of acquisition and retention of the conditioned passive avoidance behavior caused by severe hypobaric hypoxia in rats

The purpose of this study was to determine whether mild hypobaric hypoxic preconditioning provides protection against learning deficit caused by subsequent more severe hypoxia insult. Learning was examined using a passive avoidance task. Three groups of Wistar male rats: the intact and exposed to either severe hypoxia (160 Torr, exposition 3 h) or mild hypobaric hypoxic preconditioning (360 Torr, exposition 2 h, repeated three or six times daily) followed by severe hypoxia, were included in this study. In experiment 1 a passive avoidance response was acquired in 15 min immediately after hypoxia. In experiment 2 rats were exposed to hypoxia in 60 min after the acquisition of passive avoidance response. The mild hypobaric hypoxic preconditioning significantly attenuated the hypoxia-induced learning deficit in rats in Experiments 1 and 2. In experiment 1 the mild hypobaric hypoxic preconditioning repeated six times was more effective in protection against learning deficit in hypoxia exposed rats than in the case of triple mild hypobaric hypoxic preconditioning. The amount of rats suffered irreversible respiratory arrest was also assessed in this study. It was found that 50% of rats exposed to severe hypoxia died in consequence of this pathology, whereas in rats preconditioned before the severe hypoxia only 15% died for this reason. The overall results indicate that the mild hypobaric hypoxic preconditioning significantly increases CNS resistance to severe hypoxia in rats.     

Upregulation of transcription factor NRF2-mediated oxidative stress response pathway in rat brain under short-term chronic hypobaric hypoxia

Exposure to high altitude (and thus hypobaric hypoxia) induces electrophysiological, metabolic, and morphological modifications in the brain leading to several neurological clinical syndromes. Despite the known fact that hypoxia episodes in brain are a common factor for many neuropathologies, limited information is available on the underlying cellular and molecular mechanisms. In this study, we investigated the temporal effect of short-term (0–12 h) chronic hypobaric hypoxia on global gene expression of rat brain followed by detailed canonical pathway analysis and regulatory network identification. Our analysis revealed significant alteration of 33, 17, 53, 81, and 296 genes (p < 0.05, <1.5-fold) after 0.5, 1, 3, 6, and 12 h of hypoxia, respectively. Biological processes like regulation, metabolic, and transport pathways are temporally activated along with anti- and proinflammatory signaling networks like PI3K/AKT, NF-κB, ERK/MAPK, IL-6 and IL-8 signaling. Irrespective of exposure durations, nuclear factor (erythroid-derived 2)-like 2 (NRF2)-mediated oxidative stress response pathway and genes were detected at all time points suggesting activation of NRF2-ARE antioxidant defense system. The results were further validated by assessing the expression levels of selected genes in temporal as well as brain regions with quantitative RT-PCR and western blot. In conclusion, our whole brain approach with temporal monitoring of gene expression patterns during hypobaric hypoxia has resulted in (1) deciphering sequence of pathways and signaling networks activated during onset of hypoxia, and (2) elucidation of NRF2-orchestrated antioxidant response as a major intrinsic defense mechanism. The results of this study will aid in better understanding and management of hypoxia-induced brain pathologies.     

Myocardial ER chaperone activation and protein degradation occurs due to synergistic,not individual,cold and hypoxic stress

Environmental stress at high altitude affects the myocardium at the physiological and molecular level. Characterized by hypobaric hypoxia and low temperatures, the cumulative impact of these stressors on the protein folding homeostasis in the heart is yet unexplored. The present study evaluates the collective effect of cold and hypoxia on the myocardial protein oxidation and activation of the endoplasmic reticulum (ER) stress response. Adult rats were exposed to either a singular acute stress of cold (10 °C; C), hypobaric hypoxia (7620 m; H) or simultaneously to both cold and hypobaric hypoxia (CH) for 6 h. Hypoxic stress amplified the free radical generation in H and CH groups, leading to enhanced HIF-1α expression. Coupled to cold stress, reduced oxygen availability caused substantial protein oxidative modifications, as well as cardiac tissue injury and matrix remodeling, evident in the histological staining. Presence of oxidized proteins caused a significant upregulation in expression of ER chaperones GRP78 and PDI in the cold hypoxia exposed animals. Enhanced proteolytic activity signaled the removal of misfolded proteins. Linked intricately to cellular stress response, cell survival kinases were expressed higher in CH group; however apoptotic CHOP (C/EBP homologous protein) expression remained unaltered. Administration of ER stress inducer, tunicamycin along with cold hypoxic stress, caused a discernible increase in protein oxidation and GRP78 expression, along with a significant elevation in proteasome and apoptotic activity. Highlighting the significance of a synergistic, rather than individual, effect of low oxygen and temperature on the protein folding machinery, our study provides evidence for the activation of ER stress response in the myocardium under acute high altitude stress.     

Mechanism of salidroside relieving the acute hypoxia-induced myocardial injury through the PI3K/Akt pathway

ObjectiveThe objective was to investigate the anti-inflammatory effects of salidroside through the PI3K/Akt signaling pathway and its protective effects on acute hypoxia-induced myocardial injury in rats.MethodsA total of 24 healthy Sprague-Dawley male rats were selected as the experimental subjects. All rats were divided into 4 groups by using the random number table method, with 6 rats in each group. The groups included the normal control group, the salidroside group, the hypobaric hypoxia group, and the hypobaric hypoxia + salidroside group. Rats in the salidroside group were fed in the original animal laboratory and were intragastrically administered with salidroside every morning at a dosage of 35 mg/kg. Rats in the normal control group were intragastrically administered with an equal dosage of saline. Rats in the hypobaric hypoxia + salidroside group were intragastrically administered with salidroside every morning at a dosage of 35 mg/kg, who were fed in the hypoxic experiment module for animals. The altitude was increased to 4000 m, and the rats were kept in the module for 24 h. Rats in the hypobaric hypoxia group were intragastrically administered with an equal dosage of saline in the same environment, and the altitude was increased to 4000 m after administration. Parameters of blood gas analysis, histopathological changes in cardiac tissues, cardiac indexes, and inflammatory factors IL-6 and TNF-α levels of rats in groups were compared.Results1. The cardiac indexes of rats in groups were compared. The differences between the hypobaric hypoxia group and the hypobaric hypoxia + salidroside group were statistically significant (P < 0.05). 2. The results of blood gas analysis of rats in groups were compared. The differences between the hypobaric hypoxia group and the hypobaric hypoxia + salidroside group were significantly different (P < 0.05). 3. In the hypobaric hypoxia group, the myocardial cells of rats were arranged disorderly and shaped differently, with cases such as edema, degeneration, necrosis, nucleus pyknosis, and massive infiltration of inflammatory cells. In the hypobaric hypoxia + salidroside group, the above-mentioned pathological changes in myocardial cells were relieved. 4. Compared with the hypobaric hypoxia group, in the hypobaric hypoxia + salidroside group, the concentrations of IL-6 and TNF-α in rats decreased apparently, and the differences were statistically significant (P < 0.05).ConclusionSalidroside had the repairing and protective effects on the hypobaric hypoxia-induced myocardial injuries in rats. The application of salidroside could reduce the inflammatory responses of rats with hypobaric hypoxia-induced myocardial injuries through PI3K/Akt signaling pathway, thereby protecting the myocardial cells.     

Anticonvulsant and Antioxidant Effects of Cyano-carvone and Its Action on Acetylcholinesterase Activity in Mice Hippocampus

The anticonvulsant effect of cyano-carvone, a monoterpene monocyclic, was investigated in epilepsy model induced by pilocarpine. Cyano-carvone at doses of 25, 50 or 75 mg/kg promoted a reduction of 16.7, 33 and 66.7%, respectively, against pilocarpine-induced seizures, and it was efficacious in increasing both the latency to first seizures and the survival percentage, resulting in 33.3, 67 and 91.7% of protection against death induced by seizures, respectively (P < 0.05). The reference drug atropine (25 mg/kg) also produced a significant protection (100%). Its monoterpene, at 25, 50 and 75 mg/kg, was also capable to increase the latency for installation of status epilepticus induced by pilocarpine, and presented a significant protection against lipid peroxidation and nitrite formation in mice hippocampus (P < 0.05). In addition, it was observed that the cyano-carvone pretreatment increased the acetylcholinesterase activity in mice hippocampus after pilocarpine-induced seizures. The present results clearly indicate the anticonvulsant ability of cyano-carvone, which can be, at least in part, explained by the increased activity of the acetylcholinesterase enzyme. Our data suggest that the action mechanism can also be due to a direct activation of the antioxidant enzymes that could be associated with a reduction observed in oxidative stress in mice hippocampus, probably involving an inhibition of free radical production.     

锌对急性缺氧小鼠海马NOS和nNOS水平的影响

目的：观察锌对急性缺氧小鼠海马一氧化氮合酶（nitric oxide synthase,NOS）和神经元型一氧化氮合酶（neuronal NOS,nNOS）阳性神经元的影响,以探讨锌抗脑缺氧的作用机制。方法：复制小鼠急性缺氧模型,采用NADPH-d组织化学和nNOS免疫组织化学方法,研究给锌组和不给锌组急性缺氧小鼠海马各分区NOS和nNOS阳性神经元数量的变化。结果：给锌组比不给锌组小鼠缺氧耐受时间显著延长,差异有显著性（P〈0．05）;海马及其CA1区NOS和nNOS阳性神经元的数量明显减少,差异有显著性（P〈0．05）。结论：急性缺氧时锌通过减少海马NoS和nNOS水平而发挥其抗脑缺氧作用。     

Effects of Mutant Huntingtin on mGluR5-Mediated Dual Signaling Pathways: Implications for Therapeutic Interventions

Glutamate excitotoxicity is thought to play an important role in Huntington’s disease (HD), which is caused by a polyglutamine expansion in the HD protein huntingtin (htt). Overactivation of group I metabotropic glutamate receptors (mGluRs), which include mGluR1 as well as mGluR5 and are coupled via phospholipase C to the inositol phosphate pathway, is found to be involved in mutant htt-mediated neurotoxicity. However, activation of mGluR5 also leads to neuronal protection. Here, we report that mutant htt can activate both mGluR5-mediated ERK and JNK signaling pathways. While increased JNK signaling causes cell death, activation of ERK signaling pathway is protective against cell death. Expression of mutant htt in cultured cells causes greater activation of JNK than ERK. These findings suggest that selective inhibition of the JNK signaling pathway may offer an effective therapeutic approach for reducing htt-mediated excitotoxicity.     

Yohimbine Enhances Protection of Berberine against LPS-Induced Mouse Lethality through Multiple Mechanisms

Sepsis remains a major cause of mortality in intensive care units, better therapies are urgently needed. Gram-negative bacterial lipopolysaccharide (LPS) is an important trigger of sepsis. We have demonstrated that berberine (Ber) protects against lethality induced by LPS, which is enhanced by yohimbine (Y) pretreatment, and Ber combined with Y also improves survival in septic mice. However, the precise mechanisms by which Y enhances protection of Ber against LPS - induced lethality remain unclear. The present study confirmed that simultaneously administered Y also enhanced protection of Ber against LPS-induced lethality. Ber or/and Y attenuated liver injury, but not renal injury in LPS-challenged mice. Ber or/and Y all inhibited LPS-stimulated IκBα, JNK and ERK phosphorylation, NF-κB activation as well as TNF-α production. Ber also increased IL-10 production in LPS-challenged mice, which was enhanced by Y. Furthermore, Ber or/and Y all suppressed LPS-induced IRF3, TyK2 and STAT1 phosphorylation, as well as IFN-β and IP-10 mRNA expression in spleen of mice at 1 h after LPS challenge. Especially, Y enhanced the inhibitory effect of Ber on LPS-induced IP-10 mRNA expression. In vitro experiments further demonstrated that Y significantly enhanced the inhibitory effect of Ber on TNF-α production in LPS-treated peritoneal macrophages, Ber combined with Y promoted LPS-induced IL-10 production and LPS-stimulated IκBα, JNK, ERK and IRF3 phosphorylation and NF-κB activation were also suppressed by Ber or/and Y pretreatment in peritoneal macrophages. Taken together, these results demonstrate that Y enhances the protection of Ber against LPS-induced lethality in mice via attenuating liver injury, upregulating IL-10 production and suppressing IκBα, JNK, ERK and IRF3 phosphorylation. Ber combined with Y may be an effective immunomodulator agent for the prevention of sepsis.     

The effect of hyperbaric oxygen preconditioning on heat shock protein 72 expression following in vitro stress in human monocytes

Hyperbaric oxygen (HBO) is thought to confer protection to cells via a cellular response to free radicals. This process may involve increased expression of heat shock proteins, in particular the highly inducible heat shock protein 72 (Hsp72). Healthy male volunteers (n = 16) were subjected to HBO for 1 h at 2.8 ATA. Inducible Hsp72 expression was measured by flow cytometry pre-, post- and 4 h-post HBO. Peripheral blood mononuclear cells (PBMC) were isolated from whole blood via density centrifugation pre-, post- and 4 h post-HBO. PBMC were then subjected to an in vitro heat shock at 40°C or hypoxia at 37°C (5% O₂) with a control at 37°C. Cells were then analysed for Hsp72 expression by flow cytometry. Monocytes showed no significant changes in Hsp72 expression following HBO. No detectable Hsp72 was seen in lymphocytes or neutrophils. Following in vitro hypoxic exposure, a significant increase in Hsp72 expression was observed in monocytes isolated immediately post- (p = 0.006) and 4 h post-HBO (p = 0.010) in comparison to control values. HBO does not induce Hsp72 expression in PBMC. The reported benefits of HBO in terms of pre-conditioning are not due to inducement of Hsp72 expression in circulating blood cells, but may involve an enhancement of the stress response.     

+]-Huperzine A protects against soman toxicity in guinea pigs

The chemical warfare nerve agent (CWNA) soman irreversibly inhibits acetylcholinesterase (AChE) causing seizure, neuropathology and neurobehavioral deficits. Pyridostigmine bromide (PB), the currently approved pretreatment for soman, is a reversible AChE inhibitor that does not cross the blood–brain barrier (BBB) to protect against central nervous system damage. [−]-Huperzine A, a natural reversible AChE inhibitor, rapidly passes through the BBB and has numerous neuroprotective properties that are beneficial for protection against soman. However, [−]-Huperzine A is toxic at higher doses due to potent AChE inhibition which limits the utilization of its neuroprotective properties. [+]-Huperzine A, a synthetic stereoisomer of [−]-Huperzine A and a weak inhibitor of AChE, is non-toxic. In this study, we evaluated the efficacy of [+]-Huperzine A for protection against soman toxicity in guinea pigs. Pretreatments with [+]-Huperzine A, i.m., significantly increased the survival rate in a dose-dependent manner against 1.2× LD₅₀ soman exposures. Behavioral signs of soman toxicity were significantly reduced in 20 and 40 mg/kg [+]-Huperzine A treated animals at 4 and 24 h compared to vehicle and PB controls. Electroencephalogram (EEG) power spectral analysis showed that [+]-Huperzine A significantly reduces soman-induced seizure compared to PB. [+]-Huperzine A (40 mg/kg) preserved higher blood and brain AChE activity compared to PB in soman exposed animals. These data suggest that [+]-Huperzine A protects against soman toxicity stronger than PB and warrant further development as a potent medical countermeasure against CWNA poisoning.     

Circadian and ultradian extrasystole rhythms in healthy individuals at elevated versus lowland altitudes

We defined chronobiologic norms for supraventricular and ventricular single extrasystoles (SV and VE, respectively) in healthy older males in lowland areas. The study was extended to higher altitudes, where hypobaric hypoxia was expected to increase extrasystole frequency, while perhaps not changing rhythmicity. In healthy men (lowland n = 37, altitude n = 22), aged 49–72 years, mean numbers of SVs and VEs were counted over a 24-h period. Cosinor regression was used to test the 24-h rhythm and its 2nd–10th harmonics. The resulting approximating function for either extrasystole type includes its point, 95% confidence interval of the mean, and 95% tolerance for single measurement estimates. Separate hourly differences (delta) between altitude and lowland (n = 59) were also analysed. Hourly means were significantly higher in the mountains versus lowland, by +0.8 beats/h on average for SVs, and by +0.9 beats/h for VEs. A relatively rich chronogram for VEs in mountains versus lowland exists. Delta VEs clearly display a 24-h component and its 2nd, 3rd, 4th and 7th harmonics. This results in significantly higher accumulation of VEs around 8.00 a.m., 11.00 a.m. and 3.00 p.m. in the mountains. The increase in extrasystole occurrence in the mountains is probably caused by higher hypobaric hypoxia and resulting sympathetic drive. Healthy men at elevated altitudes show circadian and several ultradian rhythms of single VEs dependent on the hypoxia level. This new methodological approach—evaluating the differences between two locations using delta values—promises to provide deeper insight into the occurrence of premature beats.     

慢性间歇低压低氧暴露对小鼠空间记忆及海马谷氨酸受体磷酸化 水平的影响

目的:观察慢性间歇低压低氧暴露对成年C57小鼠认知功能、海马区p-Glu R-831、845位点蛋白表达以及海马区突触囊泡释放的影响。方法:雄性C57小鼠,随机分为对照组(n=16)与暴露组(n=16)。暴露组给予每天6 h 5000 m低压低氧暴露,持续4w;对照组无低压低氧暴露。两组小鼠其他饲养条件一致。利用Morris水迷宫实验检测每组小鼠空间记忆能力;免疫印迹实验检测Glu R1蛋白ser831和ser845位点磷酸化水平变化;透射电镜实验观察低氧对突触囊泡的影响。结果:(1)水迷宫结果显示慢性间歇低压低氧暴露后,暴露组平均逃脱潜伏期(17.6±1.69 s)显著低于对照组(27.3±1.45 s),暴露组小鼠平台搜索能力提升;(2)免疫印迹结果显示,暴露组小鼠海马Glu R1蛋白ser831和ser845位点磷酸化水平显著高于对照组小鼠;(3)透射电镜结果显示,暴露组小鼠海马区突触囊泡数目显著多于对照组,且差异有统计学意义。结论:慢性间歇低压低氧暴露可以显著提升C57小鼠空间认知功能,其机制可能是通过增加Glu R1蛋白ser831和ser845位点磷酸化水平,并增加突触结构内囊泡数目。     

银杏内酯B和低氧预适应对小鼠急性缺氧损伤的保护作用

目的：通过观察缺氧预适应和银杏内酯B预处理对小鼠急性缺氧的影响,了解银杏内酯B的脑保护作用。方法：采用小鼠常压缺氧模型,观察小鼠的行为学并记录各组小鼠的最后死亡时间,脑组织含水量,用RT-PCR、Western blot分别检测各组小鼠皮层组织中RTP801mRNA表达和EPO蛋白表达。结果：银杏内酯B和低氧预适应均能明显延长常压缺氧小鼠的存活时间,降低脑水肿程度,并且银杏内酯组和低氧预适应组RTP801mRNA表达和EPO的表达均明显增加。结论：银杏内酯B与低氧预适应具有相类似的对抗小鼠急性低氧的作用,其脑保护作用与上调RTPS01mRNA和EPO蛋白的表达有关。     

Volume changes in the forearm and lower limbs during 2 h of acute hypobaric hypoxia in nonacclimatized subjects

 To investigate the role of fluid shifts during the short-term adjustment to acute hypobaric hypoxia (AHH), the changes in lower limb (LV) and forearm volumes (FV) were measured using a strain-gauge plethysmograph technique in ten healthy volunteers exposed to different altitudes (450 m, 2500 m, 3500 m, 4500 m) in a hypobaric chamber. Arterial blood pressure, heart rate, arterial oxygen saturation (S _aO₂), endtidal gases, minute ventilation and urine flow were also determined. A control experiment was performed with an analogous protocol under normobaric normoxic conditions. The results showed mean decreases both in LV and FV of −0.52 (SD 0.39) ml · 100 ml⁻¹ and −0.65 (SD 0.32) ml · 100 ml⁻¹, respectively, in the hypoxia experiments [controls: LV −0.28 (SD 0.37), FV −0.41 (SD 0.47) ml · 100 ml⁻¹]. Descent to normoxia resulted in further small but not significant decreases in mean LV [−0.02 (SD 0.11) ml · 100 ml⁻¹], whereas mean FV tended to increase slightly [ + 0.02 (SD 0.14) ml · 100 ml⁻¹]; in the control experiments mean LV and FV decreased continuously during the corresponding times [−0.19 (SD 0.31), −0.18 (SD 0.10) ml · 100 ml⁻¹, respectively]. During the whole AHH, mean urine flow increased significantly from 0.84 (SD 0.41) ml · min⁻¹ to 3.29 (SD 1.43) ml · min⁻¹ in contrast to the control conditions. We concluded that peripheral fluid volume shifts form a part of the hypoxia-induced acute cardiovascular changes at high altitude. In contrast to the often reported formation of peripheral oedema after prolonged exposure to hypobaric hypoxia, the results provided no evidence for the development of peripheral oedema during acute induction to high altitude. However, the marked increase in interindividual variance in S _aO₂ and urine flow points to the appearance of the first differences in the short-term adjustment even after 2 h of acute hypobaric hypoxia. Accepted: 27 August 1996     

17-AAG,a Hsp90 inhibitor,attenuates the hypoxia-induced expression of SDF-1α and ILK in mouse RPE cells

The aim of this study was to investigate the changes of SDF-1α and ILK expression in mouse retinal pigment epithelium (RPE) cells in response to hypoxia, and the effect of 17-Allylamino-17-demethoxygeldanamycin (17-AAG), a heat shock protein 90 (Hsp90) inhibitor, on the hypoxia-induced expression of SDF-1α and ILK. RPE cells were cultured with 200 μmol/L cobalt chloride (CoCl₂) for different times (1, 3, 6, 12, 24, 72 h) to imitate chemical hypoxia. Pretreatment of 17-AAG was 1 h prior to hypoxic insult. Cellular viability after 17-AAG treatment was assessed by MTT assay, and the changes of SDF-1α and ILK expression were examined by RT-PCR and Western blot. Up-regulation of SDF-1α and ILK expression in response to hypoxia was observed. One hour pretreatment of 17-AAG could remarkably decreased the hypoxia-induced SDF-1α and ILK expression in vitro. Our results indicated that SDF-1α and ILK involved in the hypoxic response of RPE cells, and 1 h pretreatment of 17-AAG had an inhibitive effect on the hypoxia-induced SDF-1α and ILK expression.