Photothrombotic Occlusion of Rat Middle Cerebral Artery: Histopathological and Hemodynamic Sequelae of Acute Recanalization

Abstract

The histopathological and hemodynamic consequences of photochemically induced middle cerebral artery (MCA) thrombosis and recanalization were studied in the rat. Recanalization of the thrombosed MCA segment was achieved by the topical application of nimodipine at 1 h following photochemically induced occlusion. Pathological consequences of permanent and temporary occlusion were compared by morphometric procedures 7 days following thrombus formation. Rats with permanent thrombosis exhibited consistent infarction of both striatum and cortex. MCA recanalization at 1 h was associated with a significant reduction in total infarct volume. In recanalized rats, small cortical infarcts, confined to the peripheral MCA territory, were observed in only three of six rats. In contrast, a mixed pattern of infarction and ischemic cell damage was documented throughout the striatum in all rats. Local CBF (ICBF), measured autoradiographically, was significantly reduced in the MCA territory following 1 h of MCA occlusion, especially within the striatum. At 1 h after recanalization, lCBF recovered within the previously ischemic brain regions to >50% of control. Perfusion deficits were detected by carbon black infusion within focal areas of the striatum following reperfusion. Thus, cortical neurons appear to tolerate 1 h of MCA occlusion in this model. In contrast, reperfusion following 1 h of photochemically induced MCA occlusion gives rise to selective injury to the striatum.

Does a relative perfusion measure predict cerebral infarct size?

“…Although 14 C-iodoantipyrine autoradiography is a reliable quantitative method for evaluation of absolute local parenchymal perfusion (16), it has the methodologic limitation of evaluating absolute CBF distributions only at a single time point (12,15).…”

Applications of Dye‐sensitized Photoreactions in Neurobiology

“…The effects of short-term and permanent sensitized photothrombotic occlusion of the middle cerebral artery in rats on the histopathology of the resulting ischemic and infarcted areas of the brain have been examined; blood flow in the damaged regions of the brain was also measured (Nakayama et al, 1988). Sensitized phototreatment of the common carotid artery of the rat results in the localized formation of aggregates of platelets; later, platelet aggregates, presumably emboli from the aggregated material in the carotid artery, produce cerebral infarcts (Futrell et a/.…”

Postischemic (S)-emopamil therapy ameliorates focal ischemic brain injury in rats.

“…As some degree of reperfusion is common in human ischemic stroke and serves to alter the resulting histopathologic picture, 32 it will be important in future studies to assess the therapeutic efficacy of (S)-emopamil in the latter setting as well. This is particularly relevant in that therapeutic thrombolysis is currently under active clinical scrutiny in the setting of ischemic stroke.…”