Neuroprotective effects of caspase-3 inhibition on functional recovery and tissue sparing after acute spinal cord injury.
METHODS
We used gene microarrays and found that caspase-related death genes were upregulated. We tested caspase inhibition and evaluated its effect on the spinal cord after traumatic injury.


OBJECTIVE
The logical extension of previous studies was to determine whether downstream CASP genes might also be involved and whether inhibition might prevent injury-induced cell death.


BACKGROUND
Apoptotic cell death occurs in all endogenous cellular compartments of the spinal cord, peaking at 3 days after injury in neurons, astrocytes, and microglia. The downstream effector caspase-3 cleaves several important cellular sites after being activated by upstream initiator caspases. Along with others, we have previously identified caspase signature cleavage of PARP, alpha-fodrin, and DFF45/ICAD in the injured rat spinal cord. We also showed rapid upregulation of caspase-3 gene expression along with localization of active caspase-3 in neurons and activated microglia after SCI. Others have reported that a more general active-site mimetic peptide ketone, benzylocarbonyl-Val-Ala-Asp-fluromethylketone (zVAD-fmk) was neuroprotective after rat spinal cord injury (SCI).


METHODS
In this study, we administered the caspase-3 subfamily tetrapeptide cell permeable inhibitor Z-Asp(O-Me)-Glu(O-Me)-Val-Asp(O-Me) fluoromethyl ketone (DEVD-fmk) intraperitoneally 1 hour after laminectomy and moderate (25 g cm force) SCI in rats. RESULTS.: We used the open field locomotor rating (LRS) over a 14-day course and found statistically significant improvement in DEVD-fmk-treated rats, LRS, 9.8 +/- 0.93 SEM, compared with vehicle, 6.6 +/- 0.4 (P < 0.05). Histologic analysis of percent spinal cord tissue volume spared was 50% greater for DEVD-fmk versus control (P < 0.5).


CONCLUSIONS
These results indicate neuroprotection at both the cellular level and with substantial functional recovery, suggesting caspase-3 inhibition may be a viable therapy in the early hours after experimental SCI.
Citron
Bruce A
BA
Neurobiology Research Laboratory, Veterans Affairs Medical Center, Kansas City, MO 64128, USA.
Arnold
Paul M
PM
Haynes
Neal G
NG
Ameenuddin
Syed
S
Farooque
Mohammed
M
Santacruz
Karen
K
Festoff
Barry W
BW
D000208:Acute Disease; D000818:Animals; D053148:Caspase 3 / Q000378:metabolism; D061945:Caspase Inhibitors; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D009046:Motor Neurons / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D018696:Neuroprotective Agents / Q000494:pharmacology / Q000627:therapeutic use*; D011480:Protease Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000187:drug effects / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000188:drug therapy* / Q000201:enzymology* / Q000473:pathology
D061945:Caspase Inhibitors; D018696:Neuroprotective Agents; D011480:Protease Inhibitors; D053148:Caspase 3