Fluoxetine-induced downregulation of circMap2k1 signaling cascade to improve neurological function after ischemic stroke

Background: Ischemic stroke (IS) is known for its high incidence, disability, and mortality, and there is an urgent need to investigate the pathophysiological mechanisms and develop novel treatment strategies.

Objectives: We aimed to investigate the mechanisms of the novel circMap2k1/miR-135b-5p/Pidd1 axis in the treatment of IS progression with fluoxetine.

Methods: The middle cerebral artery occlusion (MCAO) model was done in adult male Sprague-Dawley (SD) rats and followed by fluoxetine treatment and the injection of adeno-associated virus (AAV)-sh-ctr and AAV-sh-circMap2k1 into the bilateral hippocampal tissues of rats. Dual-luciferase reporter gene assay was employed to confirm the binding between miR-135b-5p and Pidd1. Enzyme-linked immunosorbent assay was performed to measure the concentrations of the inflammatory factors TNF-α, IL-6, and IL-1β in the plasma. The role of circMap2k1 in cells was tested by overexpression of circMap2k1. Cell viability was assessed using Cell Counting Kit-8 assay, while apoptosis was measured by flow cytometry.

Results: Knockdown of circMap2k1 enhanced the therapeutic and protective effect of fluoxetine on IS injury in rats. Dual-luciferase reporter gene assay confirmed the targeting of miR-135b-5p to Pidd1. Additionally, fluoxetine deactivated the adsorption of miR-135b-5p by downregulating circMap2k1, and miR-135b-5p further exerted its inhibitory effect on Pidd1 and finally attenuated the inflammatory response caused by microglial polarization after IS. Cell experiments revealed that overexpression of circMap2k1 repressed cell viability and promoted cell apoptosis.

Conclusions: Fluoxetine downregulated of circMap2k1 was associated ameliorate neurological injury and inflammatory responses induced by microglial polarization after IS. The manuscript is available as a preprint at this link: doi.org/10.21203/rs.3.rs-3209057/v1.