Photothrombotically induced unilateral selective hippocampal ischemia in rat.

Abstract

INTRODUCTION: The vulnerability of hippocampal formation to ischemic insult has been documented in both humans and animal models. Ischemic injury induction through photothrombosis is an invasive and reproducible model of ischemic stroke which provides the ability to induce ischemia selectively in any desired area. In this study, we describe a method to induce selective unilateral hippocampal ischemia in rat through modified photothrombotic model. METHODS: Male wistar rats (n&#x202f;=&#x202f;66) were subjected to stereotaxic surgery to insert a guide cannula just above the ascending part of hippocampal fissure. After recovery femoral vein was cannulated and rats were mounted in stereotaxic frame to optical fiber insertion in guide cannula and illumination of hippocampal fissure for 25&#x202f;min. Rose Bengal dye was slowly injected through femoral vein during the first two-minute of illumination. Twenty-four hours later, infarct volume and histological change were evaluated in rat hippocampus. Cognitive function was also evaluated 48&#x202f;h after ischemia induction. RESULTS: This procedure caused significant neuronal necrosis and infarct formation in the right hemisphere hippocampus. The infarct size was consisted in different subjects and was paralleled to cognitive impairment. The mean volume of infarction was 6.5% which affected whole right hippocampus and caused significant cognitive impairment compared to sham group (P&#x202f;< 0.001). DISCUSSION: The method described in this study provides the ability of selective hippocampal ischemia induction and study of hippocampal injury consequences following ischemia or other neurodegenerative disease that affect hippocampus.