Liposome-entrapped superoxide dismutase ameliorates infarct volume in focal cerebral ischaemia.

We studied the role of superoxide radicals in the pathogenesis of focal ischaemic brain injury using liposome-entrapped copper-zinc-superoxide dismutase which can penetrate the blood-brain barrier and cell membranes efficiently. Superoxide dismutase activities were significantly elevated in the blood and in the normal brain tissue 1, 2, 8, and 24 hours after a bolus intravenous administration of liposome-entrapped copper-zinc-superoxide dismutase. Copper-zinc-superoxide dismutase activities were also increased significantly in the ischaemic hemisphere and the contralateral cortex as well. The infarct sizes were reduced by 33%, 24% and 18%, respectively, for the anterior artery area, middle artery area, and posterior artery area by treatment at 24 hours following the injection of liposome-entrapped superoxide dismutase. These data demonstrate that superoxide radicals are important determinants of the size of an infarct following focal cerebral ischaemia, and that liposome-entrapped copper-zinc-superoxide dismutase may have pharmacological value for focal cerebral ischaemic injury.