Estrogen Treatment Attenuates Apoptotic Cell Death Following Spinal Cord Injury in Rats

Abstract

Estrogen exerts a neuroprotective effect by reducing apoptotic cell death in both brain injury and spinalcord injury. This study investigated whether estrogen contributes to the cleavage of poly (ADP-ribose)polymerase (PARP), an indicator of apoptotic cell death, during spinal cord injury. Adult female rats wereovariectomized and treated with oil or estrogen prior to spinal cord injury. Spinal cord tissues werecollected at 24 hr after injury. Estrogen treatment showed a significant improvement of spinal cord tissuemorphology and markedly reduced numbers of terminal deoxynucleotidyl transferase-mediated dUTPnick-end labeling (TUNEL)-positive cells. Using Western blot analysis, we found that the level of cleavedPARP was increased in oil-treated animals, whereas estrogen prevented the injury-induced increase inPARP cleavage. The results of this study provide further evidence that estrogen inhibits apoptotic celldeath through the down-regulation of cleaved PARP in spinal cord injury.