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Caspase Inhibitor z-DEVD-fmk Attenuates Calpain and Necrotic Cell Death in Vitro and after Traumatic Brain Injury

2004; SAGE Publishing; Volume: 24; Issue: 10 Linguagem: Inglês

10.1097/01.wcb.0000138664.17682.32

1559-7016

Susan M. Knoblach, Daniel A. Alroy, Maria Nikolaeva, Ibolja Černak, Bogdan A. Stoica, Alan I. Faden,

Connexins and lens biology

In studies designed to evaluate the therapeutic window for treatment of traumatic brain injury, the caspase 3 inhibitor z-DEVD-fmk improved neurologic function and reduced lesion volumes when administered at 1 but not at 4, 8, or 24 hours after injury. Moreover, neither caspase 3 nor PARP, a caspase 3 substrate, were cleaved in injured, untreated cortex from 1 to 72 hours after injury. Few cortical neurons expressed active caspase 3 or were TUNEL positive from 6 to 24 hours after injury, and TUNEL staining was primarily Type I (necrotic). Nissl staining revealed extensive neuronal necrosis in the injured cortex from 6 to 24 hours after impact. Considered together, these data suggested that z-DEVD-fmk may reduce neuronal necrosis, so we used an in vitro model of necrotic cell death induced by maitotoxin to test this further and explore the potential mechanism(s) involved. Z-DEVD-fmk (1 nM-100 microM) significantly attenuated maitotoxin induced neuronal cell death and markedly reduced expression of the 145 kD calpain-mediated alpha-spectrin breakdown product after maitotoxin injury. Neither the 120 kD caspase-mediated alpha-spectrin cleavage product nor cathepsin B were expressed after maitotoxin injury. In a cell free assay, z-DEVD-fmk reduced hydrolysis of casein by purified calpain I. Finally, z-DEVD-fmk reduced expression of the 145 kD calpain-mediated alpha-spectrin cleavage fragment after traumatic brain injury in vivo. These data suggest that neuroprotection by z-DEVD-fmk may, in part, reflect inhibition of calpain-related necrotic cell death.