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

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

SummaryIn 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 μM) significantly attenuated maitotoxin induced neuronal cell death and markedly reduced expression of the 145 kD calpain-mediated α-spectrin breakdown product after maitotoxin injury. Neither the 120 kD caspase-mediated α-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 α-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.Journal of Cerebral Blood Flow & Metabolism (2004) 24, 1119–1132; doi:10.1097/01.WCB.0000138664.17682.32

BRAIN injuries; INSULIN synthesis inhibitors; HYDROLYSIS; PROTEIN hydrolysates; MEMBRANE proteins; CELL death

Journal of Cerebral Blood Flow & Metabolism, 2004, Vol 24, Issue 10, p1119

0271-678X

Academic Journal

10.1097/01.WCB.0000138664.17682.32