title: Protein kinase C expression and activity after global incomplete cerebral ischemia in dogs.
abstract: OBJECTIVE
  Studies suggest that protein kinase C (PKC) activation during ischemia plays an important role in glutamate neurotoxicity and that PKC inhibition may be neuroprotective. We tested the hypothesis that elevations in the biochemical activity and protein expression of Ca2+-dependent PKC isoforms occur in hippocampus and cerebellum during the period of delayed neurodegeneration after mild brain ischemia.
  
  
  METHODS
  We used a dog model of 20 minutes of global incomplete ischemia followed by either 6 hours, 1 day, or 7 days of recovery. Changes in PKC expression (Western blotting and immunocytochemistry) and biochemical activity were compared with neuropathology (percent ischemically damaged neurons) by means of hematoxylin and eosin staining.
  
  
  RESULTS
  The percentage of ischemically damaged neurons increased from 13+/-4% to 52+/-10% in CA1 and 24+/-11% to 69+/-6% in cerebellar Purkinje cells from 1 to 7 days, respectively. The occurrence of neuronal injury was accompanied by sustained increases in PKC activity (240% and 211% of control in hippocampus and cerebellum, respectively) and increased protein phosphorylation as detected by proteins containing phosphoserine residues. By Western blotting, the membrane-enriched fraction showed postischemic changes in protein expression with increases of 146+/-64% of control in hippocampal PKCalpha and increases of 138+/-38% of control in cerebellar PKCalpha, but no changes in PKCbeta and PKCgamma were observed. By immunocytochemistry, the neuropil of CA1 and CA4 in hippocampus and the radial glia in the molecular layer of cerebellum showed increased PKCalpha expression after ischemia.
  
  
  CONCLUSIONS
  This study shows that during the period of progressive ischemic neurodegeneration there are regionally specific increases in PKC activity, isoform-specific increases in membrane-associated PKC, and elevated protein phosphorylation at serine sites.
authors.affiliation: Department of Anesthesiology, the Johns Hopkins Medical Institutions, Baltimore, MD, USA. fsieber@welchlink.welch.jhu.edu
authors.forename: F E
authors.initials: FE
authors.lastname: Sieber
authors.forename: R J
authors.initials: RJ
authors.lastname: Traystman
authors.forename: P R
authors.initials: PR
authors.lastname: Brown
authors.forename: L J
authors.initials: LJ
authors.lastname: Martin
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism* / Q000473:pathology; D002531:Cerebellum / Q000378:metabolism; D004285:Dogs; D006624:Hippocampus / Q000378:metabolism; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000473:pathology; D010768:Phosphoserine / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D007527:Isoenzymes; D009419:Nerve Tissue Proteins; D010768:Phosphoserine; D011493:Protein Kinase C