A REPRODUCIBLE MODEL OF MIDDLE CEREBRAL INFARCTS, COMPATIBLE WITH LONG-TERM SURVIVAL, IN AGED RATS

Background and Purpose Stroke is a disease associated with aging, but experimental stroke studies are generally done in young male animals. Because there are numerous differences associated with aging, such as an altered immune system and altered neurochemistry, that could affect the outcome of these experiments, a model of reproducible cerebral in farction in aged rats is needed. Methods We attempted to produce middl e cerebral artery (MCA) infarcts in aged (22 months of age) rats using two standard methods. A nylon suture with a heat-induced bulb was pas sed through the external carotid artery in seven animals, with an atte mpt to place the tip at the origin of the MCA. The MCA was ligated thr ough a craniotomy just proximal to the internal cerebral vein in 14 ra ts. Survival potential was tested by attempting 2-week survival in fou r rats and 2-month survival in one rat. Results The suture model faile d to produce MCA infarcts, even when the bulb of the suture was proper ly placed in the MCA. The intracranial MCA occlusion resulted in repro ducible MCA infarcts. There were no deaths, including the animals allo wed to survive 2 weeks and 2 months. Conclusions We conclude that repr oducible MCA infarcts can be produced in aged rats by craniotomy and t hat these lesions may be compatible with long-term survival. This shou ld be a useful technique for studying therapeutic interventions and re habilitation strategies in an animal model that immunologically and ne urochemically more closely resembles humans at risk for stroke.