Acrolein-mediated mechanisms of neuronal death

It is well known that traumatic injury in the central nervous system can be viewed as a primary injury and a secondary injury. Increases in oxidative stress lead to breakdown of membrane lipids (lipid peroxidation) during secondary injury. Acrolein, an alpha,beta-unsaturated aldehyde, together with other aldehydes, increases as a result of self-propagating lipid peroxidation. Historically, most research on the pathology of secondary injury has focused on reactive oxygen species (ROS) rather than lipid peroxidation products. Little is known about the toxicology and cell death mediated by these aldehydes. In this study, we investigated and characterized certain features of cell death induced by acrolein on PC12 cells as well as cells from dorsal root ganglion (DRG) and sympathetic ganglion in vitro. In the companion paper, we evaluated a possible means to interfere with this toxicity by application of a compound that can bind to and inactivate acrolein. Here we use both light and atomic force microscopy to study cell morphology after exposure to acrolein. Administration of 100 microM acrolein caused a dramatic change in cell morphology as early as 4 hr. Cytoskeletal structures significantly deteriorated after exposure to 100 microM acrolein as demonstrated by fluorescence microscopy, whereas calpain activity increased significantly at this concentration. Cell viability assays indicated significant cell death with 100 microM acrolein by 4 hr. Caspase 3 activity and DNA fragmentation assays were performed and supported the notion that 100 microM acrolein induced PC12 cell death by the mechanism of necrosis, not apoptosis.