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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Preconditioning the brain with sublethal cerebral ischemia induces tolerance to subsequent lethal periods of ischemia (ischemic tolerance). The purpose of this study is to investigate the role of low-molecular weight stress proteins, 27-kDa heat shock protein (HSP27) and alpha B crystallin, in ischemic tolerance. We measured the content of these proteins with enzyme immunoassay in the rat hippocampus and cerebral cortex following 6 min of ischemia with and without preconditioning with 3 min of ischemia and 3 days of reperfusion. We also visualized the localization of HSP27 immunohistochemically in comparison with that of HSP70. A 3-min period of ischemia caused a 2.4-fold increase in HSP27 content in the hippocampus after 3 days. Immunohistochemical localization of HSP27 was found in glial cells in all subregions of the hippocampus, whereas HSP70 immunostaining was seen only in CA1 pyramidal neurons. HSP27 content in the hippocampus decreased 2 h after 6 min of ischemia. HSP27 content progressively increased in the unpreconditioned hippocampus after 1 and 3 days, but returned to preischemic levels in the preconditioned hippocampus. HSP27 and HSP70 immunostaining was seen in CA1 pyramidal neurons after 1 day both with and without preconditioning. After 3 and 7 days, an intense HSP27 staining was observed in reactive glial cells in the CA1 without preconditioning, whereas the staining decreased in the preconditioned hippocampus. HSP70 staining was seen only in neurons at these time points. We observed no significant changes in HSP27 content in the cerebral cortex although neurons in the third and fifth layers were immunostained after 1 and 3 days. We observed no alterations in alpha B crystallin content after ischemia both in the hippocampus and the cortex. The present study demonstrated that cerebral ischemia induces HSP27 expression but not alpha B crystallin. Both HSP27 and HSP70 induction had a good temporal correlation with the induction of ischemic tolerance. However, different sites of action were suggested because the localization and cell types of HSP27 induction were quite different from those of HSP70 induction. The result suggests that it is unlikely that HSP27 is directly involved in the protection afforded by ischemic preconditioning.
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PMID:Induction of 27-kDa heat shock protein following cerebral ischemia in a rat model of ischemic tolerance. 813 Oct 73

The distribution of heat shock protein hsp70 mRNA after 10 min of middle cerebral artery (MCA) occlusion was investigated through in situ hybridization in transgenic (Tg) mice overexpressing CuZn-superoxide dismutase (CuZn-SOD) and in control nontransgenic (nTg) littermates. In the ischemic cortex of nTg mice, hsp70 mRNA was detected 1 h after reperfusion and was observed for up to 6 h. In Tg mice, however, it was still detectable within the cortex even at 24 h. In the caudate putamen, hsp70 mRNA appeared at 1 h and was present for up to 6 h in both nTg and Tg mice. Although hsp70 mRNA was detected in the thalamus only at 1 h in nTg mice, it was observed for up to 6 h in Tg mice. Similarly, hsp70 mRNA was detected in the hippocampus of nTg mice only at 1 h, whereas it was detected in Tg mice at 1 h and continued up to 24 h, with high intensity in the CA1 subfield. Despite the significant amounts of hsp70 mRNA in both Tg and nTg mice following ischemia, there was no observable neuronal necrosis (as assessed using hematoxylin and eosin staining) for up to 7 days. Cortical cerebral blood flow (CBF), measured by laser-Doppler flowmetry, did not differ between nTg and Tg mice during ischemia and reperfusion, despite exhibiting hyperemia following hypoperfusion. These results suggest that oxidative stress affects the expression of hsp70 following temporary focal ischemia. An alteration in oxidation stress, which resulted from reduced levels of superoxide radicals in the presence of the CuZn-SOD transgenes, may permit the prolonged expression of hsp70.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Prolonged expression of hsp70 mRNA following transient focal cerebral ischemia in transgenic mice overexpressing CuZn-superoxide dismutase. 816 90

It was recently reported that in rats exposure to heat shock leads to appearance of a myocardial heat shock protein (HSP 70) and to an increase in myocardial catalase activity. This correlated with an improvement in post-ischemic function either in Langendorff-perfused hearts after low-flow ischemia or in working hearts after short-term, no-flow ischemia. We investigated the effect of the same hyperthermic treatment on functional recovery from no-flow ischemia of various durations in isolated working rat hearts performing at high or low external workloads. Rats were heated to core temperature of 42 degrees C for 15 min. No significant protein oxidation (% oxidized methionine) was observed 2.5 hr after treatment. A protein with migration characteristics similar to HSP 70 was observed in hearts of heat shocked rats 24 hr after this treatment while their myocardial catalase activity was not increased. Hearts of similarly treated rats were excised 24 hr after hyperthermia and perfused in a working mode with Krebs-Henseleit buffer (1.25 mM Ca2+, 11 mM glucose). At 15 cm H2O preload and 100 cm H2O afterload after 30 min no-flow ischemia, control hearts recovered to 36.9%, 2%, 47.6%, and 21.5% of the preischemic values of heart rate-peak systolic pressure product (RPP), aortic output, coronary flow, and cardiac output, respectively. After only 25 min of ischemia the respective recovered values were 61.6%, 11.5%, 58.7%, and 33.5%. Throughout the recovery period these hemodynamic values were consistently higher in hearts of heat shocked animals than in those of control hearts but the differences were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Role of catalase in myocardial protection against ischemia in heat shocked rats. 817 41

Distribution of heat shock protein (HSP) 90 alpha mRNA induction after 10 min of transient global ischemia was investigated in gerbil hippocampus by in situ hybridization. A small amount of HSP90 alpha mRNA was normally present in hippocampal cells and the mRNA was further induced with a peak at 8 h after ischemia. In hippocampal CA1 cells that are vulnerable to ischemia, HSP90 alpha mRNA was continuously induced by 1 day and finally diminished at 2 days. The temporal profile of HSP90 alpha mRNA induction in hippocampal CA1 cells was similar to that of HSP70 mRNA reported previously, suggesting a cooperative role of HSP90 alpha with other HSPs after ischemia.
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PMID:Induction of HSP90 alpha heat shock mRNA after transient global ischemia in gerbil hippocampus. 822 Oct 63

In situ hybridization and Northern blot analysis were used to characterize the mRNA expression of alpha-tubulin, a neuroprotein crucial for neuronal structural and functional restoration, in comparison to that of the stress inducible heat shock protein-70 (HSP-70), in the same gerbil brain following 10 min of forebrain ischemia. The HSP-70 expression was noted in the dentate granule layer 1 h postischemia (PI) and became prominent in all pyramidal cell fields of the hippocampus in addition to the dentate layer at 6 h PI. The induction of HSP-70 persisted in CA1 and CA2 regions and partly in dentate gyrus for up to the 1 day PI period examined. There was no significant HSP-70 expression in any of the regions of the nonischemic or 15 min PI brain. alpha-Tubulin, on the other hand, was expressed in all pyramidal fields of the hippocampus as well as dentate gyrus in nonischemic controls. A decline was noted in the CA1 region 1 h PI onward and was maximal at 6 h PI. Its expression, however, increased at 24 h PI (significant only in comparison to 15 min and 6 h PI but not to control) when it became rather strong in the dentate gyrus. Thus, the temporal pattern of expression of alpha-tubulin sharply contrasted with that of HSP-70 in the PI brain as it declined in the vulnerable CA1 region during the 1st 24 h PI, i.e., the period when HSP-70 was induced and its expression was lowest in the 6 h group when HSP-70 peaked. It was maximum in the dentate gyrus at 24 h PI when HSP-70 was marginally detectable in that region. These studies indicate that in early recirculation period following prolonged ischemia, HSP-70 mRNA is expressed in both vulnerable regions as well as in regions of the brain that are destined to survive while alpha-tubulin is diminished in vulnerable regions. These data suggest a positive correlation between the loss of alpha-tubulin mRNA and delayed neuronal necrosis that follows in the vulnerable CA1 region.
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PMID:Comparison of alpha-tubulin mRNA and heat shock protein-70 mRNA in gerbil brain following 10 min of ischemia. 825 74

Inductions of mRNAs for heat shock protein (HSP) 70 and heat shock cognate protein (HSC) 70 were examined in the cerebral cortex, cerebellum, heart, lung, kidney, and liver of gerbils after a 10-min transient forebrain ischemia. HSP70 mRNA was normally expressed in a small amount in the cerebellum, lung, and kidney, but was not expressed in the heart or liver in a detectable amount. A very small amount of HSP70 mRNA was also present in the cerebral cortex. HSC70 mRNA was normally present in all the organs examined with a variety in the amount. Eight hours after the cerebral ischemia, the level of HSP70 mRNA increased in the cerebral cortex, lung, and kidney. HSC70 mRNA levels also increased in all the organs. However, the increase of HSC70 mRNA was remarkable in the heart. Transient cerebral ischemia caused subsequent hyperthermia. Treatment of gerbils with an artificial hyperthermia without cerebral ischemia increased the HSP70 and HSC70 mRNA levels as well. However, the HSC70 mRNA level in the heart after cerebral ischemia was much higher than that in the case with hyperthermic treatment. These results suggest that HSC70 mRNA was preferentially induced in the heart after transient forebrain ischemia that was not only due to the subsequent hyperthermia.
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PMID:Preferential expression of HSC70 heat shock mRNA in gerbil heart after transient brain ischemia. 826 47

We investigated the temporal profile of heat shock protein 70 induction in the rat hippocampus using immunohistochemistry to clarify the mechanism of ischemic tolerance following preconditioning with sublethal ischemia. Although a 6-min period of forebrain ischemia produced severe neuronal damage to the hippocampal CA1 subfield, preconditioning with 3 min of ischemia followed by three days of reperfusion protected against the CA1 neuronal damage after 6 min of ischemia. Immunohistochemical staining against heat shock protein 70 showed that the protein is induced in CA1 pyramidal cells one, three and seven days after 3 min of ischemia, the immunostaining being most intense after three days. Heat shock protein synthesis was observed in CA1, CA3 and dentate hilar neurons one and three days after 6 min of ischemia, both with and without preconditioning. In addition, the heat shock protein was stained in the CA1 2 h and seven days after 6 min of ischemia with preconditioning, but the intensity of staining was relatively weak at these time points. The results suggest that stress response induced by sublethal ischemia protects against ischemic neuronal damage, and that the induced stress response, including heat shock protein 70 synthesis during and immediately after the second ischemic episode, is correlated with the protection because late induction of the heat shock protein did not prevent neuronal death.
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PMID:Temporal profile of heat shock protein 70 synthesis in ischemic tolerance induced by preconditioning ischemia in rat hippocampus. 828 44

We studied the possible role of prior ischemic stress as a protective mechanism against cerebral infarction in rats. Two brief periods of global cerebral ischemia, separated by 24 h, did not cause cell death in brain, but did produce neuronal stress, as demonstrated by induction of the nonconstitutive 72 kDa heat shock protein (HSP72). Forty-eight hours later, animals subjected to prior ischemia had smaller infarct from permanent middle cerebral artery occlusion than did sham-operated controls. These findings support an association between ischemia-induced stress, HSP72 induction, and attenuation of injury from subsequent focal cerebral ischemia.
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PMID:Prior ischemic stress protects against experimental stroke. 830 18

To evaluate the mechanism of tolerance to ischemia, inductions of heat shock protein (HSP) 70 and heat shock cognate protein (HSC) 70 mRNAs in gerbil hippocampus were compared with in situ hybridization between cases of a single 3.5-min period of forebrain ischemia and a 3.5-min period of ischemia 2 days after 2-min pretreatment with ischemia. Immunohistochemistry for HSP70 protein and morphological studies were also performed in the same brains up to 7 days after the reperfusion. Following a single 3.5-min period of ischemia, HSP70 and HSC70 mRNAs were induced in all hippocampal cells. However, the hippocampal CA1 cells produced only a minimum of HSP70 protein, and the cells were almost lost by 7 days. Following 3.5 min of ischemia after 2-min pretreatment, large populations of the CA1 cells survived at 7 days. The peak time of the HSP70 and HSC70 mRNA induction shifted to an earlier period of reperfusion in all hippocampal cells as compared with the case of a single episode of ischemia. The peak of HSP70 and HSC70 mRNA induction shifted from 1 day to 3 h in the CA1 cells. The CA1 cells produced strongly immunoreactive HSP70 from 3 hr to 2 days. These results suggest that pretreatment with an initial period of ischemia (for 2 min) accelerated HSP70 and HSC70 gene expression at the transcriptional level, ameliorated the translational disturbance of HSP70 mRNA to protein, and saved the CA1 cells from subsequent lethal ischemia (for 3.5 min). These changes of heat shock gene expression might play important roles in the acquisition of ischemic tolerance of hippocampal CA1 neurons.
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PMID:Acceleration of HSP70 and HSC70 heat shock gene expression following transient ischemia in the preconditioned gerbil hippocampus. 836 Feb 84

The effect of bifemelane hydrochloride (BFH) on the induction of heat shock protein (HSP) 70 and heat shock cognate protein (HSC) 70 mRNAs after transient global ischemia in gerbil brain was investigated by in situ hybridization using cloned cDNA probes selective for each mRNA species. Following 3.5 min of ischemia, HSP70 and HSC70 mRNAs were induced in all hippocampal cells. The CA1 cells were almost lost by 7 days. Treatment with BFH twice before and after ischemia (total 60 mg/kg, i.p.) reduced the induction of HSP70 and HSC70 mRNAs both at 8 h and 1 day of the reperfusion, and about half of the CA1 cells survived at 7 days. Thus, the reduction of HSP70 and HSC70 mRNA inductions after ischemia may suggest that BFH reduced intra- and/or post-ischemic stress, and protected CA1 cells from ischemic damage.
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PMID:Reduction of HSP70 and HSC70 mRNA inductions by bifemelane hydrochloride after transient ischemia in gerbil brain. 836 50


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