Oclusão seletiva e permanente da artéria cerebral média em ratos: uma abordagem experimental para o estudo de déficits motores e de memória espacial

Abstract

Introduction: Ischemic stroke (IS) has high clinical relevance and demands experimental approaches capable of enabling the development of novel adjuvant therapies. Due to the similarity of cerebral vascular anatomy to that of humans, rats are widely used as experimental models of IS. However, there remains a need for methods that generate an ischemic environment more closely resembling that observed in humans, using an approach that prioritizes selective occlusion of the middle cerebral artery (MCA), the vessel most commonly employed in experimental occlusion models. Objective: To establish a reproducible method for performing craniectomy followed by permanent and selective occlusion of the middle cerebral artery (MCA) in rats, aiming to standardize the procedure, reduce technical challenges, and enable its application in studies of motor deficits and spatial memory impairment. Methods: Twenty-eight Wistar rats (N = 28) were equally allocated into two groups: a craniectomy-only group (SHAM) and a craniectomy combined with selective MCA occlusion group (SMCAO). On postoperative days 7 and 8, animals underwent the postural test and the object location recognition memory test, respectively. After euthanasia, brain tissues were sectioned and processed using Nissl staining. A detailed surgical protocol was developed to demonstrate the feasibility and effectiveness of the method, encompassing preoperative preparation, anesthesia, positioning, craniectomy, MCA occlusion, and closure. Results: The method produced significant deficits in the SMCAO group, as evidenced by the postural test (p = 0.015) and the object location recognition memory test (p < 0.001). Histological examination confirmed the selectivity of the approach, with injury localized to regions associated with the hippocampal network—such as the perirhinal, entorhinal, and piriform cortices—and the external capsule, while deeper brain structures remained preserved. Conclusions: This protocol proved to be a reproducible and effective method for inducing selective MCA ischemia in rats. It represents a valid and technically accessible experimental tool for studies investigating the pathophysiological mechanisms and potential therapeutic strategies in ischemic stroke.