Effect of Catalase on Regional Cerebral Blood Flow and Brain Edema during the Early Phase of Experimental Pneumococcal Meningitis

Previous studies have demonstrated that the radical scavenger superoxide dismutase completely blocked the increase of regional cerebral blood flow (rCBF), intracranial pressure (ICP), and brain water content during the early phase of experimental pneumococcal meningitis in the rat. To obtain information on the nature of the reactive oxygen species involved, the effect of catalase, a hydrogen peroxide scavenger,wastested. Rats injected intracisternally with livepneumococci were either untreated or received intravenous catalase. The increase of rCBF and brain water content in infected untreated rats was significantlyattenuated bycatalase 6 h after intracisternal challenge. ICP increased in both infected groups, with a trend toward lower ICP with catalase treatment. Cerebrospinal fluid white blood cell counts were not significantly different between infected groups. These results and previous experiments using superoxide dismutase suggest that the increaseofrCBF, ICP, and brain water content is mainly causedbysuperoxide or superoxide reaction products.