A selective cysteine protease inhibitor is non-toxic and cerebroprotective in rats undergoing transient middle cerebral artery ischemia

Brain Res. 2001 May 18;901(1-2):94-101. doi: 10.1016/s0006-8993(01)02289-2.


Ischemic neuronal injury mediated by cysteine proteases such as calpains and caspases has been demonstrated in various experimental models. Cathepsins B and L are also cysteine proteases which may contribute to neuronal death after ischemia. The authors measured in vitro and in vivo toxicity and post-ischemic cytoprotective effects of a cysteine protease inhibitor which does not block calpain or caspase but, rather, is relatively selective for cathepsins B and L. The compound belongs to the peptidyl-diazomethane family (cysteine protease inhibitor 1, termed CP-1). In vitro toxicity was measured using an assay of cell viability, and in vivo toxicity was measured by histological tissue analysis after infusion of CP-1 in rats. Two hours of middle cerebral artery (MCA) occlusion in rats was performed by the intravascular suture method. Immediately following reperfusion, intravenous infusion of CP-1 or vehicle was performed for 4 h at 0.9 ml/h. After a 7-day survival, the infarct volumes were measured. CP-1 was non-toxic to cultured glial cells to a local concentration of 200 microM, and relatively non-toxic to cultured endothelial cells at concentrations of 100-200 microM. No animal exhibited toxic effects at any of the doses used. Histologic comparisons revealed no signs of tissue toxicity. CP-1 significantly reduced hemispheric infarct volume compared to control (37+/-8.2%) at concentrations of 10, 50, and 250 microM [22+/-15%, P=0.008; 20+/-13%, P=0.002; 23+/-15%, P=0.022, respectively (mean+/-standard deviation; N=7-10 per group)]. CP-1, at the concentration of 50 microM, improved the functional score of the animals, but did not significantly alter cerebral blood flow. This study supports the hypothesis that the lysosomal cathepsins B and/or L contribute to cerebral injury after focal ischemia with reperfusion. Cysteine protease inhibitors which are relatively selective for cathepsins B and L, but not the calpains or caspases, are effective at reducing infarct volume after intravenous post-ischemic administration.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Blood Glucose / drug effects
  • Brain / drug effects
  • Brain / metabolism
  • Brain / physiopathology
  • Brain Ischemia / drug therapy*
  • Brain Ischemia / metabolism
  • Brain Ischemia / physiopathology
  • Cardiovascular Physiological Phenomena / drug effects
  • Cathepsin B / drug effects
  • Cathepsin B / metabolism
  • Cathepsin L
  • Cathepsins / drug effects
  • Cathepsins / metabolism
  • Cell Death / drug effects*
  • Cell Death / physiology
  • Cerebrovascular Circulation / drug effects
  • Cerebrovascular Circulation / physiology
  • Cysteine Endopeptidases
  • Cysteine Proteinase Inhibitors / toxicity*
  • Diazomethane / analogs & derivatives
  • Diazomethane / pharmacology
  • Dipeptides / pharmacology
  • Dose-Response Relationship, Drug
  • Endopeptidases*
  • Infarction, Middle Cerebral Artery / drug therapy
  • Infarction, Middle Cerebral Artery / metabolism
  • Infarction, Middle Cerebral Artery / physiopathology
  • Injections, Intravenous
  • Male
  • Nerve Degeneration / drug therapy*
  • Nerve Degeneration / metabolism
  • Nerve Degeneration / physiopathology
  • Neuroprotective Agents / pharmacology*
  • Neurotoxins / toxicity
  • Rats
  • Rats, Wistar
  • Reperfusion Injury / drug therapy*
  • Reperfusion Injury / metabolism
  • Reperfusion Injury / physiopathology
  • Tumor Cells, Cultured / cytology
  • Tumor Cells, Cultured / drug effects
  • Tumor Cells, Cultured / metabolism


  • Blood Glucose
  • Cysteine Proteinase Inhibitors
  • Dipeptides
  • Neuroprotective Agents
  • Neurotoxins
  • carbobenoxy-phenylalanyl-serine(O-benzyl)diazomethane
  • Diazomethane
  • Cathepsins
  • Endopeptidases
  • Cysteine Endopeptidases
  • Cathepsin B
  • Cathepsin L
  • Ctsl protein, rat