Age effect on motor recovery in a post-acute animal stroke model

Male Fischer 344 rats aged 3, 6, 12, 18 and 24 months were trained to walk on a narrow beam, then lesioned in the right hindlimb sensorimotor cortex by photothrombosis. Motor performance was measured daily for 60 days using a 7-point rating scale from which deficit scores were calculated. Tissue analysis included lesion volume measurement after Nissl staining. Animals aged 3 and 6 months fully recovered by day 10 and 31, respectively. Animals aged 18 months acquired significant neurological impairment that persisted greater than 60 days. Deficit scores were significantly greater than in groups aged 12, 6 and 3 months. Degenerative morbidity and mortality confounded behavioral study of animals aged 24 months. The duration of neurological impairment after photochemical sensorimotor cortex lesion increased with age. Animals aged 18 months at lesion acquired the greatest chronic impairment. This aged post-acute animal model is clinically relevant to stroke rehabilitation.