This article details the procedure for performing transient middle cerebral artery occlusion (MCAO) in mice, a model for studying stroke. The methodology includes surgical techniques to temporarily block blood flow to the brain, simulating stroke conditions.
The neck region of the mouse has a pair of common carotid arteries, or CCA. As the left CCA advances toward the head region, it bifurcates into the external carotid artery, or ECA, and the internal carotid artery, or ICA. The ICA branches further, forming the middle cerebral artery, or MCA, which supplies oxygenated blood to the brain. Any disruption to the blood flow within the MCA can cause a stroke.
To perform transient middle cerebral artery occlusion, or MCAO, place an anesthetized mouse in the supine position. Make a small incision on the neck. Retract the skin and muscle layers to locate the CCA and ligate it, stopping the blood flow toward the brain. Subsequently, use a removable surgical clip to ligate the ICA transiently.
Place two slightly distant sutures to ensure a tight and a loose ligation around the ECA before reaching the bifurcation point of the ICA. Make a small incision between the two ECA sutures and insert the silicon-coated filament intraluminally into the ECA.
Remove the clip clamping the ICA. Advance the filament further through the length of the ICA until the filament head blocks the origin of the MCA. With all the sutures in place, close the surgery site. Return the mouse to the cage and monitor it.
Transient MCAO causes an abrupt reduction in the blood flow, eventually leading to a stroke.
Turn the mouse to the supine position, then put the snout into the anesthesia cone, and fix the paws with tape. Disinfect the skin and hair surrounding the chest, and make a 2 centimeter long midline incision in the neck.
Use forceps to pull the skin, submandibular gland, and sternomastoid muscle apart. Use retractors to expose the surgical field and find the left common carotid artery or CCA.
Dissect the CCA free from connective tissue and surrounding nerves, without harming the vagal nerve, and perform a transient ligation before the bifurcation. Dissect the external carotid artery or ECA and tie a permanent knot at the most distal, visible part.
Place another suture under the ECA, and close to the bifurcation, then prepare a loose knot to be used later. Dissect the internal carotid artery, or ICA, and place a microvascular clip on it about 5 millimeters over the bifurcation. Make sure not to damage the vagal nerve. Then, cut a small hole into the ECA between the tight and the loose ligations, ensuring not to cut the entire ECA.
Introduce the filament and advance it towards the CCA. Tighten the loose ligation in the ECA around the lumen to momentarily secure the filament in that position, removing the microvascular clip, and prevent bleeding. After removing the microvascular clip, insert the filament through the ICA until the origin of the MCA is reached. Fix the filament in this position by further tightening the knot around the ECA. Remove the retractor and relocate the sternomastoid muscle in the submandibular gland before suturing the wound.
繁體中文
