Abstract
Purpose: Most pre-clinical stroke studies address the acute phase after
injury, with less attention to long-term effects of injury, treatment, and experimental
testing itself. We addressed these questions: 1) Will functional deficits persist up to 8
weeks following transient stroke in older animals? 2) Will functional deficits resolve
spontaneously, with time and/or repeated behavioral testing?
Methods: Male Sprague-Dawley rats (12 months) were pre-trained on behavioral
tasks to provide baseline data and then underwent transient middle artery occlusion
(tMCAO) or sham surgery. We measured motor, sensory, cognitive and gait impairments over 8
weeks, and the extent of hemispheric brain infarction. One cohort underwent behavioral
testing once at 8 weeks post-stroke (LT); a second cohort (RLT) was tested at 3, 6 and 8
weeks post-stroke.
Results: Significant deficits were exhibited in all functional outcomes in
both cohorts after 8 weeks. We observed some recovery in some behavioral parameters in
both cohorts at 8 weeks.
Conclusions: Deficits persist for at least 8 weeks after tMCAO. The greater
spontaneous recovery seen in the RLT groups suggest that repeated testing did reduce the
severity of these stroke-induced impairments. These findings have implications for
designing future studies of agents to induce long-term functional recovery following
stroke.
