Calpain Inhibition Prevents Ethanol-Induced Alterations in Spinal Motoneurons

Abstract

Long-term exposure of ethanol (EtOH) alters the structure and function in brain and spinal cord. The present study addresses the mechanisms of EtOH-induced damaging effects on spinal motoneurons in vitro. Altered morphology and biochemical changes of such damage were demonstrated by in situ Wright staining and DNA ladder assay. EtOH at low to moderate (25-50mM) concentrations induced damaging effects in the motoneuronal scaffold which involved activation of proteases like μ-calpain and caspase-3. Caspase-8 was seen only at higher (100mM) EtOH concentration. Further, pretreatment with calpeptin, a potent calpain inhibitor, confirmed the involvement of active proteases in EtOH-induced damage to motoneurons. The lysosomal enzyme cathepsin D was also elevated in the motoneurons by EtOH, and this effect was significantly attenuated by inhibitor treatment. Overall, EtOH exposure rendered spinal motoneurons vulnerable to damage, and calpeptin provided protection, suggesting a critical role of calpain activation in EtOH-induced alterations in spinal motoneurons.