THE PRESENCE OF 4-HYDROXYNONENAL PROTEIN COMPLEX AS AN INDICATOR OF OXIDATIVE STRESS AFTER EXPERIMENTAL SPINAL-CORD CONTUSION IN A RAT MODEL/

Object. The authors tested the hypothesis that breach of the blood-spi nal cord barrier (BSCB) will produce evidence of oxidative stress and that a similar staining pattern will be seen between 4-hydroxynonenal (HNE)/protein complexes and extravasated immunoglobulin G (Igc). Metho ds. Adult female Fischer 344 rats, each weighing 200 to 225 g, were su bjected to a spinal cord contusion at T-10 by means of a weight-drop d evice. Spinal cord tissue was assessed for oxidative stress by localiz ing extravasated plasma contents with a monoclonal antibody for rat Ig G and protein conjugation with HNE, which is an aldehyde byproduct of lipid peroxidation. The animals were killed at 1 and 6 hours, and 1, 2 , and 7 days after surgery. Maximum HNE/protein staining was observed at 2 days postinjury, and HNE/protein and IgG manifested similar stain ing patterns. Analysis revealed a graduated but asymmetrical rostral-c audal response relative to the T-10 injury site. Both HNE/protein comp lex and IgG staining revealed that the caudal levels T-11 and T-12 sta ined significantly more intensely than the rostral levels T-9 and T-8, respectively. A higher percentage of neurons positive for HNE/protein immunostaining was observed in spinal cord levels caudal to the injur y site compared with equidistant rostral regions. Protein dot-blot ass ays also revealed a similar asymmetrical rostral-caudal HNE/protein co ntent. To analyze the timing of the BSCB breach. another group of anim als received identical contusions, and horseradish peroxidase (HRP) wa s injected 10 minutes before or at various times after injury (1, 3, a nd 6 hours, and 1, 2, and 7 days). Maximum HRP permeability was seen i mmediately after injury, with a significant decrease occurring by 1 ho ur and a return to control levels by 2 days posttrauma. Conclusions. D ata from this study indicate possible compromise of neuronal, axonal, glial, and synaptic function after trauma, which may be a factor in mo tor deficits seen in animals after spinal cord contusion. The colocali zation of the Ige stain with the HNE/protein stain is consistent with the hypothesis of a mutual cause-effect relationship between BSCB and oxidative stress in central nervous system trauma.