title: Relationship between metabolic dysfunctions, gene responses and delayed cell death after mild focal cerebral ischemia in mice.
abstract: The evolution of brain injury was examined in mice subjected to focal cerebral ischemia as induced by 30 min of intraluminar thread occlusion of the middle cerebral artery, followed by 3 h to 3 days of reperfusion. Metabolic dysfunctions were studied by 3H-leucine autoradiography for the measurement of cerebral protein synthesis and by regional ATP bioluminescent imaging. Metabolic changes were compared with responses of the genes c-fos, c-jun, heat-shock protein gene (hsp)72, p53-activated gene (pag)608 and caspase-3, which were investigated by in situ hybridization histochemistry and immunocytochemistry, and correlated with the degree of DNA fragmentation, as assessed by the terminal TdT-mediated dUTP-biotin nick end labeling method. Intraluminar thread occlusion led to a reproducible reduction of cerebral laser Doppler flow to 20-30% of control. Thread withdrawal was followed by a short-lasting post-ischemic hyperperfusion to approximately 120%. In non-ischemic control animals, fractional protein synthesis values of 0.81+/-0.26 and 0.94+/-0.23 were obtained. Thread occlusion resulted in a suppression of protein synthesis throughout the territory of the middle cerebral artery after 3 h of reperfusion (0.04+/-0.08 in caudate-putamen and 0.14+/-0.19 in somatosensory cortex, P<0.05). Protein synthesis partly recovered in the cortex after 24 h and 3 days (0.71+/-0.40 and 0.63+/-0.26, respectively), but remained suppressed in the caudate-putamen (0.14+/-0.22 and 0.28+/-0.28). Regional ATP levels did not show any major disturbances at the reperfusion times examined. Thread occlusion resulted in a transient increase of c-fos mRNA levels in ischemic and non-ischemic parts of the cortex and caudate-putamen at 3 h after ischemia, which suggests that spreading depressions were elicited in the tissue. At the same time, c-jun and hsp72 mRNAs were elevated only in ischemic brain areas showing inhibition of protein synthesis. C-fos and c-jun responses completely disappeared within 24 h of reperfusion. Hsp72 mRNA levels remained elevated in the cortex after 24 h, but decreased to basal values in the caudate-putamen. Twenty-four hours after reperfusion, pag608 and caspase-3 mRNA levels increased in the caudate-putamen, where protein synthesis rates were still reduced, and remained elevated even after 3 days. However, pag608 and caspase-3 mRNA levels did not increase in the cortex, where protein synthesis recovered. After 24 h and 3 days, functionally active p20 fragment of caspase-3 was detected in the caudate-putamen, closely associated with the appearance of DNA fragmented cells. Neither activated caspase-3 nor DNA fragmentation were noticed in the cortex.In summary, the suppression of protein synthesis is reversible in the ischemia-resistant cortex following 30 min of thread occlusion in mice, but persists in the vulnerable caudate-putamen. In the caudate-putamen, apoptotic programs are induced, closely in parallel with the manifestation of delayed cell death. Thus, the recovery of protein synthesis may be a major factor influencing tissue survival after transient focal ischemia.
authors.affiliation: Department of Experimental Neurology, Max-Planck-Institute for Neurological Research, Cologne, Germany. dirk.hermann@uni-tuebingen.de
authors.forename: D M
authors.initials: DM
authors.lastname: Hermann
authors.forename: E
authors.initials: E
authors.lastname: Kilic
authors.forename: R
authors.initials: R
authors.lastname: Hata
authors.forename: K A
authors.initials: KA
authors.lastname: Hossmann
authors.forename: G
authors.initials: G
authors.lastname: Mies
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D002545:Brain Ischemia / Q000235:genetics* / Q000378:metabolism* / Q000503:physiopathology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004734:Energy Metabolism / Q000502:physiology*; D015870:Gene Expression / Q000502:physiology*; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D007930:Leucine / Q000493:pharmacokinetics; D008163:Luminescent Measurements; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D016601:RNA-Binding Proteins; D015427:Reperfusion Injury / Q000235:genetics* / Q000378:metabolism* / Q000503:physiopathology; D013997:Time Factors
chemical_list: D004268:DNA-Binding Proteins; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D016601:RNA-Binding Proteins; C491518:Wig1 protein, mouse; D000255:Adenosine Triphosphate; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D007930:Leucine