Superoxide dismutase activity is not affected by closed head injury in rats

Superoxide anion radicals are generated in association with prostaglandin production, and are implied in the mediation of secondary brain damage following cerebral ischemia or injury. In a model of closed head injury in rats we have demonstrated the activation of phospholipase A₂ (PLA₂) and the increased production of eicosanoids in the post-trauma period. In the present study we investigated the role of superoxide dismutase (SOD) in this model. Head trauma was induced over the left cerebral hemisphere of ether anesthetized rats by a calibrated weight drop device. Cortical tissue samples were taken 15 min, 4 and 24 h later. SOD activity was assayed by its ability to inhibit the xanthine oxidase-cytochrome c reduction. There was no significant change in SOD activity in any of the regions studied - the site of injury, and contralateral region as well as the remote frontal lobes of both hemispheres. Although intense PLA₂activity and production of eicosanoids was previously found in some of these regions, activity of SOD was unaffected. These results do not support an important role for endogenous SOD up to 24 h after head injury.