Behavioral efficacy of posttraumatic calpain inhibition is not accompanied by reduced spectrin proteolysis, cortical lesion, or apoptosis

Kathryn E. Saatman, Chen Zhang, Raymond T. Bartus, Tracy K. McIntosh

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

Administration of the selective calpain inhibitor AK295 has been shown to attenuate motor and cognitive dysfunction after brain trauma in rats. To explore mechanisms underlying the behavioral efficacy of posttraumatic calpain inhibition, we investigated histologic consequences of AK295 administration. Anesthetized Sprague-Dawley rats received lateral fluid percussion brain injury of moderate severity (2.2 to 2.4 atm) or served as uninjured controls. At 15 minutes after injury, animals were randomly assigned to receive a 48-hour infusion of either 2 mmol/L AK295 (120 to 140 mg/kg) or saline via the carotid artery. At 48 hours and 1 week after injury, spectrin fragments generated specifically by calpain were detected by Western blotting and immunohistochemistry, respectively, in saline-treated, brain- injured animals. Interestingly, equivalent spectrin breakdown was observed in AK295-treated animals when cortical and hippocampal regions were evaluated. Similarly, administration of the calpain inhibitor did not attenuate cortical lesion size or the numbers of apoptotic cells in the cortex, subcortical white matter, or hippocampus, as verified by terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nick-end labeling and morphology, at 48 hours after injury. These data suggest that an overt reduction in spectrin proteolysis, cortical lesion, or apoptotic cell death at 48 hours or 1 week is not required for behavioral improvements associated with calpain inhibition by AK295 after experimental brain injury in rats.

Original languageEnglish
Pages (from-to)66-73
Number of pages8
JournalJournal of Cerebral Blood Flow and Metabolism
Volume20
Issue number1
DOIs
StatePublished - 2000

Keywords

  • Calcium-activated protease
  • Cytoskeleton
  • Histology
  • Rat
  • Traumatic brain injury

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Cardiology and Cardiovascular Medicine

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