Abstract
Abstract only Introduction: Rehabilitative physical therapy is essential for reducing stroke-related functional deficits; however, comorbidities may limit patient participation. Whole body vibration (WBV; 40 Hz) offers an exercise-like alternative. Our studies show that one month of post-stroke WBV reduces ischemic damage and improves motor and cognitive function in middle-aged rats. Notably, WBV significantly increased circulating irisin, a muscle-derived hormone. We hypothesize that post-stroke WBV modifies the cerebral transcriptome and irisin treatment improves stroke outcome in middle-aged female rats. Methods: Middle-aged Sprague-Dawley rats were randomized to sham or transient middle cerebral artery occlusion (tMCAO; 90 min) surgery and divided into two cohorts. A cohort received either no-WBV (steady platform) or WBV (platform vibrating at 40 Hz) for 15 minutes twice a day for a week. Cortical tissue was then collected for RNA sequencing (RNAseq) and gene enrichment analysis. The second cohort received either saline or irisin (PeproTech, 0.2 µg/g BW) treatment at 4.5 hours post-tMCAO and then once a week for a month. At 21 days post-tMCAO, rats were assessed for cognitive deficits via the Morris water maze. At 1-month post-tMCAO, brains were collected for histological analysis. Results: RNAseq revealed significant (p<0.05) differential expression of 581 genes in the cortex due to WBV. Specifically, there was downregulation (log 2 (fold change) = -2.9; p= 0.03943) of Calcium Voltage-Gated Channel Auxiliary Subunit Gamma 7 ( Cacng7 ) and calcium-release channel activity (GO:0015278), which are both implicated in excitotoxicity following stroke. The expression of Vacuolar Protein Sorting-Associated Protein 37C ( Vps37c ), a component of an endosomal sorting complex that mediates apoptosis, was also downregulated (log 2 (fold change) = -7.1; p= 0.01888). In our second cohort, rats treated with irisin for 1-month post-tMCAO, as compared to saline, demonstrated significantly (p<0.05) reduced cognitive deficits in spatial learning (hidden platform) and memory (probe trial). Additionally, irisin treatment significantly (p<0.05) reduced infarct damage at 1-month post-tMCAO. Conclusion: Post-stroke WBV increases the expression of genes responsible for ischemic tolerance and irisin treatment improves cognitive outcomes in middle-aged rats. Future studies are needed to understand the underlying mechanism(s) responsible for irisin-conferred ischemic protection.