calpastatin and Cerebral-Infarction

Two intracellular cysteine proteases (calpains and caspases) and inducible nitric oxide synthase (iNOS) participate in the ischemic brain injury. In vitro nitric oxide (NO) regulates calpain and caspase-3 activation. The present study investigated whether aminoguanidine (AG), an iNOS inhibitor, protected brain against experimental stroke through inhibiting calpain and caspase-3 activation. Rats received 1h ischemia by intraluminal filament, then, reperfused for 23 h (R 23 h). AG (100 mg/kg) was administered intraperitoneally 5 min before ischemia. Our data showed that treatment with AG markedly improved neurological deficit, reduced brain swelling, decreased infarct volume, and attenuated the necrotic cell death in ischemic penumbra and core, and apoptotic cell death in penumbra at R 23 h. Enzymatic studies demonstrated the significant inhibition of the activities of mu- and m-calpain and caspase-3, and Western blot analysis revealed marked increases in the levels of MAP-2 and spectrin in penumbra and core in AG-treated rats versus vehicle-treated rats. AG also significantly enhanced the calpastatin levels in core, although it had no significant effects on that in penumbra. These data demonstrate that inhibiting calpain and caspase-3 activation is one mechanism of AG against experimental stroke, suggesting that NO produced by iNOS may be involved in calpain- and caspase-3-mediated ischemic cell death, at least in part.

Topics: Animals; Apoptosis; Biotransformation; Blotting, Western; Brain; Brain Edema; Calcium-Binding Proteins; Calpain; Caspase 3; Cerebral Infarction; Cytosol; Enzyme Activation; Guanidines; Male; Microtubule-Associated Proteins; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Recovery of Function; Spectrin; Stroke

Calpastatin, a naturally occurring protein, is the only inhibitor that is specific for calpain. A novel blood-brain barrier (BBB)-permeant calpastatin-based calpain inhibitor, named B27-HYD, was developed and used to assess calpain's contribution to neurological dysfunction after stroke in rats. Postischemic administration of B27-HYD reduced infarct volume and neurological deficits by 35% and 44%, respectively, compared to untreated animals. We also show that the pharmacologic intervention has engaged the intended biologic target. Our data further demonstrates the potential utility of SBDP145, a signature biomarker of acute brain injury, in evaluating possible mechanisms of calpain in the pathogenesis of stroke and as an adjunct in guiding therapeutic decision making.

Topics: Animals; Blood-Brain Barrier; Brain; Calcium-Binding Proteins; Calpain; Cerebral Infarction; Cysteine Proteinase Inhibitors; Disease Models, Animal; Male; Peptide Fragments; Rats; Rats, Wistar; Spectrin