Article

Benign focal ischemic preconditioning induces neuronal Hsp70 and prolonged astrogliosis with expression of Hsp27

Laboratory of Molecular Neurobiology, Department of Anatomy and Neurobiology, Faculty of Medicine, Dalhousie University, Halifax, Canada.
Brain Research (Impact Factor: 2.83). 05/2000; 863(1-2):169-81. DOI: 10.1016/S0006-8993(00)02133-8
Source: PubMed

ABSTRACT We have established a focal preconditioning (PC) paradigm that produces significant and prolonged ischemic tolerance (IT) of the brain to subsequent permanent middle cerebral artery occlusion (MCAO). PC using 10 min of MCAO induces brain tolerance at 1-7 days of reperfusion that requires active protein synthesis. The protective protein(s) involved are unknown. In these studies the increased transcription and translation of the inducible 70-kDa heat shock protein (Hsp70) and the 27-kDa heat shock protein (Hsp27), and astrogliosis/glial fibrillary acidic protein (GFAP) were determined by Northern analysis and immunohistochemistry following PC. Cellular localization of proteins was determined by double labeling. PC produced no brain injury but did increase Hsp70 mRNA transiently at 6 h and increased Hsp27 mRNA later at 24 h for at least 5 days. Protein expression induced by PC exhibited a similar profile. Hsp70 protein was primarily expressed in neurons from 1 to 5 days post-PC throughout the PC cortex. Hsp27 protein expression was initiated later for a much longer period of time. A remarkable astroglyosis was verified with increased astrocytic Hsp27 from 1 to 7 days after PC. Gliosis with increased Hsp27 in the PC cortex was still present but reduced 4 weeks after PC. Therefore, PC that results in brain tolerance/neuroprotection increases neuronal Hsp70 in the PC cortex and activated astrocytic Hsp27 in the PC cortex in a temporal fashion associated with developing IT. The short duration of benign ischemia (PC) that produces IT produces a robust, long-lived cellular and protein synthetic response that extends throughout the entire cortex (i.e. well beyond the MCA perfusion territory). The resulting IT is associated with changes in astrocyte-activation that might provide increased support and protection from injury. Although both Hsp70 and Hsp27 may participate in the neuroprotection/brain tolerance induced by PC, the temporal expression patterns of these proteins indicate that they are not solely responsible for the tolerance to brain injury.

0 Followers
 · 
71 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Recombinant 70 kDa heat shock protein (Hsp70) is an antiapoptotic protein that has a cell protective activity in stress stimuli and thus could be a useful therapeutic agent in the management of patients with acute ischemic stroke. The neuroprotective and neurotherapeutic activity of recombinant Hsp70 was explored in a model of experimental stroke in rats. Ischemia was produced by the occlusion of the middle cerebral artery for 45 minutes. To assess its neuroprotective capacity, Hsp70, at various concentrations, was intravenously injected 20 minutes prior to ischemia. Forty-eight hours after ischemia, rats were sacrificed and brain tissue sections were stained with 2% triphenyl tetrazolium chloride. Preliminary treatment with Hsp70 significantly reduced the ischemic zone (optimal response at 2.5 mg/kg). To assess Hsp70's neurotherapeutic activity, we intravenously administered Hsp70 via the tail vein 2 hours after reperfusion (2 hours and 45 minutes after ischemia). Rats were then kept alive for 72 hours. The ischemic region was analyzed using a high-field 11 T MRI scanner. Administration of the Hsp70 decreased the infarction zone in a dose-dependent manner with an optimal (threefold) therapeutic response at 5 mg/kg. Long-term treatment of the ischemic rats with Hsp70 formulated in alginate granules with retarded release of protein further reduced the infarct volume in the brain as well as apoptotic area (annexin V staining). Due to its high neurotherapeutic potential, prolonged delivery of Hsp70 could be useful in the management of acute ischemic stroke.
    Drug Design, Development and Therapy 01/2014; 8:639-50. DOI:10.2147/DDDT.S62024 · 3.03 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: This study aimed to study the dynamic changes of B cell lymphoma/leukaemia 2 (Bcl-2), caspase-3 and heat shock response protein 70 (Hsp70) in blood serum following acute middle cerebral artery occlusion (MCAO) in rats. Methods: Occlusion of the cerebral artery was accomplished via the intraluminal filament, followed by the TTC staining evaluation and neurological deficit score. Meanwhile, the blood serum was extracted at 0.5, 2, 3, 6, 12 and 24 hours and 3 and 7 days after surgery. The serum expression levels of caspase-3, Bcl-2 and Hsp70 were determined using ELISA kits according to the manufacturer’s protocols. Expression correlations between Bcl-2 and Hsp70, Bcl-2 and caspase-3 were analysed using correl function. A rats model was successfully established. Results: The expression of all three indexes, including Bcl-2, caspase-3 and Hsp70, was significantly increased after surgery (p < 0.05) and peaked at 12, 24 and 24 hours, respectively. Up to 7 days after MCAO, the expression levels of these proteins recovered to the control levels. There were positive correlations between the expressions of Bcl-2 and Hsp70, Bcl-2 and caspase-3 (p < 0.05). Conclusions: The altered expressions of these proteins in the blood serum may result in many symptoms in acute ischaemic stroke individuals.
    Brain Injury 08/2014; 29(1). DOI:10.3109/02699052.2014.945958 · 1.86 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Inducible heat shock proteins (Hsps) are upregulated in the central nervous system in response to a wide variety of injuries. Surprisingly, however, no coherent picture has emerged regarding the magnitude, duration and cellular distribution of inducible Hsps in the visual system following injury to retinal ganglion cells (RGCs). The current study sought, therefore, to achieve the following two objectives. The first aim of this study was to systematically characterise the patterns of Hsp27 and -70 expression in the retina and optic nerve in four discrete models of retinal ganglion cell (RGC) degeneration: axonal injury (ON crush), somato-dendritic injury (NMDA-induced excitotoxicity), chronic hypoperfusion (bilateral occlusion of the carotid arteris) and experimental glaucoma. The second aim was to document Hsp27 and -70 expression in the optic tract, the subcortical retinorecipient areas of the brain, and the visual cortex during Wallerian degeneration of RGC axons. Hsp27 was robustly upregulated in the retina in each injury paradigm, with the chronic models, 2VO and experimental glaucoma, displaying a more persistent Hsp27 transcriptional response than the acute models. Hsp27 expression was always associated with astrocytes and with a subset of RGCs in each of the models excluding NMDA. Hsp27 was present within astrocytes of the optic nerve/optic tract in control rats. During Wallerian degeneration, Hsp27 was upregulated in the optic nerve/optic tract and expressed de novo by astrocytes in the lateral geniculate nucleus and the stratum opticum of the superior colliculus. Conversely, the results of our study indicate Hsp70 was minimally induced in any of the models of injury, either in the retina, or in the optic nerve/optic tract, or in the subcortical, retinorecipient areas of the brain. The findings of the present study augment our understanding of the involvement of Hsp27 and Hsp70 in the response of the visual system to RGC degeneration.
    PLoS ONE 12/2014; 9(12):e114838. DOI:10.1371/journal.pone.0114838 · 3.53 Impact Factor