Electroacupuncture pretreatment alleviates spasticity after stroke in rats by inducing the NF-κB/NLRP3 signaling pathway and the gut-brain axis

Abstract

Objective: Spasticity is one of the most prevalent ischemic stroke sequelae and the leading cause of disability after stroke. Although electroacupuncture pretreatment has been shown to be effective in the treatment of ischemic stroke, its therapeutic effect and mechanism on post-stroke spasm remain unknown. The purpose of this study was to look into the potential mechanism of electroacupuncture pretreatment in inducing the NF-κB/NLRP3 signaling pathway and the gut-brain axis in the therapy of spasm after stroke.

Methods: After electroacupuncture treatment at Baihui (DU20) and Qubin (G87), the rat model of middle cerebral artery occlusion (MCAO) was first established. HE, Nissl, and TUNEL staining were used to detect pathological alterations in the rat brain. The relative levels of IL-4, IL-6, TNF-α, and TMAO were determined by ELISA. qRT-PCR and Western blot were used to evaluate the mRNA and protein levels of NF-κB p65, NLRP3, caspase3 and caspase9. Gas chromatography-mass spectrometry (GC-MS) was used to determine the levels of short-chain fatty acids (SCFAs) in rat gut.

Results: Hippocampal cells from rats with spasticity following stroke in the MCAO group were chaotic and loosely distributed with an unclear border, a blurred nucleolus, and vanished cytoplasm when compared to those from the sham operation group. Furthermore, the number of surviving neurons decreased while the number of apoptotic cells increased. In the I/R group, relative levels of IL-6, TNF-α, and TMAO increased considerably, while NF-κB p65, NLRP3, caspase3, and caspase9 were dramatically downregulated. The intestinal contents of n-propyl acetate and propyl butyrate were lowered in rats with spasticity following stroke. Electroacupuncture treatments miraculously remedied all of the foregoing pathogenic alterations.

Conclusion: Pretreatment with electroacupuncture relieves spasticity after stroke by decreasing the inflammatory response, suppressing the NF-κB/NLRP3 signaling pathway, and modulating the gut-brain axis by increasing n-propyl acetate and propyl butyrate levels in the bowel. Our findings establish a new molecular mechanism and theoretical foundation for electroacupuncture therapy of ischemic stroke.

Keywords: Electroacupuncture; NF-κB/NLRP3; Short-chain fatty acids; Spasticity after stroke; The gut-brain axis.