Animal models of middle cerebral artery occlusion of brain injury

Rats were anesthetized with sodium pentobarbital (50 mg/kg, intraperitoneal) and turned to the supine position, fixed to the surgical table using surgical tapes. Transient focal cerebral ischemia was induced by middle cerebral artery occlusion as described in previous literatures [40, 41]. Briefly, the left carotid artery was exposed to separate the external carotid artery and the internal carotid artery, external carotid artery was occluded at the level the middle cerebral artery branches for 60 min, using a 4-0 monofilament nylon suture (Beijing Cinontech Co. Ltd, China). After 60 min, the occlusion was removed to allow for reperfusion for 24 hours. For sham-operated rats, all the arteries were exposed during the surgical period but the filament was not inserted into the middle cerebral artery. The body temperature of the rats was maintained at 37.5±0.5°C during the surgery using a heating pad and a thermometer. For the mouse ischemia-reperfusion brain injury model, the protocol is modified from previous studies [42]. Briefly, mice were anesthetized by isoflurane and maintained under anesthesia throughout the 1-hour occlusion period. The external carotid artery was incised and a blunt-tip 6-0 nylon monofilament was used to occlude the external carotid artery. After 60 minutes, the nylon thread and the common carotid artery ligature are removed. In the sham surgery group, the arteries are visualized but not disturbed.