title: Permanent brain ischemia induces marked increments in hsp72 expression and local protein synthesis in synapses of the ischemic hemisphere.
abstract: Transient focal ischemia induced in rat brain by occlusion of the middle cerebral artery (MCAo) elicits a generalized induction of the 72 kDa heat-shock protein (hsp72) heralding functional recovery. As this effect implies activation of protein synthesis, and local systems of protein synthesis are present in brain synapses, and may be analyzed in preparations of brain synaptosomes, we evaluated hsp72 expression and protein synthesis in synaptosomal fractions of spontaneously hypertensive rats (SHRs) subjected to permanent MCAo. SHRs were randomly divided in ischemics and sham controls, anaesthesia controls and passive controls. Focal ischemia was induced under chloral hydrate anaesthesia by unilateral permanent MCAo. Protein synthesis was determined by [35S]methionine incorporation into synaptosomal proteins from ischemic and contralateral cortex/striatum, and from cerebellum. Hsp72 expression was measured in the same fractions by immunoblotting. Our data demonstrate that under these conditions synaptic hsp72 markedly increases in the ischemic hemisphere 1 and 2 days after MCAo, progressively declining in the following 2 days, while no significant change occurs in control rats. In addition, in the ischemic hemisphere the rate of synaptic protein synthesis increases more than two-fold between 1 and 4 days after MCAo, without showing signs of an impending decline. The present data provide the first demonstration that synaptic protein synthesis is massively involved in brain plastic events elicited by permanent focal ischemia.
authors.affiliation: Department of Experimental Medicine, University of Perugia, Perugia, Italy.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Mariucci
authors.forename: Michela
authors.initials: M
authors.lastname: Tantucci
authors.forename: Antonio
authors.initials: A
authors.lastname: Giuditta
authors.forename: Maria Vittoria
authors.initials: MV
authors.lastname: Ambrosini
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002545:Brain Ischemia / Q000378:metabolism* / Q000503:physiopathology; D050884:HSP72 Heat-Shock Proteins / Q000378:metabolism*; D020244:Infarction, Middle Cerebral Artery / Q000378:metabolism; D008297:Male; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D009473:Neuronal Plasticity / Q000502:physiology*; D017729:Presynaptic Terminals / Q000378:metabolism*; D051381:Rats; D011918:Rats, Inbred SHR; D020127:Recovery of Function / Q000502:physiology; D013312:Stress, Physiological / Q000378:metabolism / Q000503:physiopathology; D013574:Synaptosomes / Q000378:metabolism; D013687:Telencephalon / Q000098:blood supply / Q000378:metabolism* / Q000503:physiopathology; D013997:Time Factors; D015854:Up-Regulation / Q000502:physiology
chemical_list: D015415:Biomarkers; D050884:HSP72 Heat-Shock Proteins; D009419:Nerve Tissue Proteins