Abstract TP96: Neuroprotective Effects of IGF-1 in Middle-Aged Females Can Be Replicated by Antagomirs to microRNA (miR)-92b and miR-33a

Abstract

Background: Our previous studies show that intracerebroventricular (ICV) delivery of Insulin-like growth factor (IGF)-1 reduces MCAo-induced infarction in middle-aged female rats. Analysis of ischemic tissue at 4h showed that IGF1 treatment significantly reduced the expression of a group of miRNAs. To determine if inhibiting these miRNAs could replicate IGF-1-mediated neuroprotection, we examined the effects of antagomirs to miR-33a (A-mir33a) and miR-92b (A-mir92b) in in vivo and in vitro models of ischemia. Methods: Middle-aged (12 mo) acyclic female rats were subject to intraluminal MCAo for 90 min followed by reperfusion. Animals received a single tail vein injection of A-miR-33a, A-miR-92b, A-miR-33a+A-miR-92b or scrambled oligos (7ug/kg bwt) after 4h of reperfusion. We evaluated infarct volume (TTC staining) at 2d post stroke and behavioral recovery using neurological scores and adhesive removal test (ART). In parallel, human brain endothelial cell cultures were exposed to oxygen-glucose deprivation (OGD) in the presence of A-mir-33a, A-mir-92b or scrambled oligos. The integrity of the cell monolayer was assessed by tomato-lectin staining and cell death was assayed by LDH. Results: Single injection of A-mir92b during the acute stroke phase reduced infarct volume (p<0.04) and improved sensorimotor behavior (p<0.04) while A-mir33a treated animals were not different from scrambled control. However, the combination of A-mir-33a+A-mir-92b resulted in significantly smaller infarct volumes (p<0.04), less motor impairment (neurological score; p<0.02) and sensorimotor deficits (ART; p<0.05). In vitro studies showed that neither of the antagomirs reduced media LDH under OGD. As reported previously, OGD caused cell retraction and A-mir33a notably preserved the cell geometry (continuous lectin staining) to maintain the monolayer integrity and was similar to the normoxic control. Conclusions: IGF-1 regulated microRNAs appear to modulate specific aspects of stroke recovery. IV delivery of a combination of miRNA inhibitors may replicate the neuroprotective actions of IGF-1, thus providing a safer alternate to ICV delivery of IGF-1. Supported by R56 NS074895 and RF1 AG04218906