Effects of lecithinized superoxide dismutase on traumatic brain injury in rats

Only small amounts of superoxide dismutase (SOD) are present in the extracellular space to scavenge excess amounts of superoxide anions (O2^-) released after traumatic brain injury (TBI). Experiments were performed in rats with cerebral contusion produced by weight-drop technique. We investigated the effects of exogenous lecithinized SOD (PC-SOD) on accumulation of O2^- produced in our model, by measuring the level of SOD activity (using the NBT-reducing method) and the expression of copper, zinc- SOD (Cu, Zn-SOD) mRNA (by Northern blot analysis). As determined by tissue- specific gravity, administration of PC-SOD reduced brain edema in the periphery of the lesion 6 h after contusion. SOD activity increased in the peripheral region at 30 min after contusion, but returned to normal levels at 6 h after TBI. Administration of PC-SOD increased SOD activity up to 6 h after TBI. The expression of Cu, Zn-SOD mRNA increased in the core region, peripheral portion, and contralateral hemisphere up to 6 h after TBI, then was suppressed in all three regions by PC-SOD. Our results confirm the important role of O2^- in the development of brain edema after TBI and indicate that PC-SOD diminishes brain edema through a protective effect against O2^-.