[Photochemically induced focal cerebral infarction in rat and its pathological observation].

Cerebral infarction in Wistar rats was induced by photochemical method. A photochemical reaction was produced by the photosensitive agent rose bengal under the effects of green light (560 +/- 60 nm). This reaction released free radicals which may damage the endothelium of cerebral vessels and induce platelet aggregation, and then may cause thrombosis in cerebral parenchymal vessels. There were typical changes of thrombosis and ischemic necrosis in the irradiated region of the cerebrum under light and electron microscopy. Serial pathologic findings suggested that the critical phase of progressive necrosis lies at the time of 1-6 hours after cerebral ischemia induced photochemically. Therefore, effective protection of the brain is important in the early stage of cerebral ischemia.