Abstract WP257: Microrna-20a-3p is Neuroprotective in Both Males and Females in an Ischemic Stroke Model

Abstract

Background: Previous studies in our lab have shown that neuroprotective miRs let-7f and mir-363-3p were both only protective in females but not males. In an effort to identify a more universal miRNA-based therapeutic, a large scale profiling of astrocytic microRNA (miR) in young and middle aged male and female rats was conducted. This approach revealed that members of the mir17~92 cluster were regulated by age and sex. Mir-20a-3p, a member of this cluster, was inversely related to infarct volume, such that adult females, who display the smallest infarct volumes, had the highest expression of miR-20a-3p, while mir20a-3p was virtually absent in middle-aged females. Few validated targets of mir20a-3p are identified, however matrix metalloproteinases (MMPs) are ‘predicted’ targets of this miRNA. In view of the evidence that MMPs exacerbate blood brain barrier permeability, we hypothesize that increasing mir20a-3p expression would be neuroprotective. Therefore, the present study was designed to determine if mir20a-3p was mechanistically related to stroke outcomes. Methods: Young males (5 mo) and middle-aged female (12 mo) rats were subject to middle cerebral artery occlusion (MCAo) by stereotaxic injection of endothelin-1. At 4h post-stroke, animals received a tail-vein injection of miR-20a-3p or scrambled control. Adhesive removal test was performed pre and post MCAo to assess motor deficits. All animals were terminated at 5d post MCAo and the brains processed for infarct analysis by standard histological procedures. Results: Cortico-striatal infarct volumes at 5d post stroke were significantly reduced in the miR-20a-3p treated young males and middle-aged females. In young males, infarct volume was reduced by 24%, while in middle-aged females mir20a-3p treatment reduced infarct volume by 47% as compared to age-matched controls (p ≤ 0.05). Sticky tape test indicated significant motor recovery post-stroke in the contralateral limb in miR-20a-3p mimic treated groups as well. Conclusion: Collectively, the data suggests that exogenous post stroke miR-20a-3p treatment is more universally neuroprotective as compared to other miRNA tested previously. These findings also highlights a potential for astrocyte-targeted treatment options for stroke.