[Electroacupuncture ameliorates cognitive impairment and suppresses TLR4/MyD88/NF-κB pathway-mediated astrocyte activation in rats with vascular dementia].

Abstract

Objectives: To investigate the effects of electroacupuncture (EA) on cognitive function and neuroinflammation in a rat model of vascular dementia (VD) and the underlying mechanism.

Methods: Sixty male SD rats were randomly assigned to sham-operated group (n=10) and VD model group (n=50) receiving bilateral common carotid artery occlusion. Thirty rats with successful VD modeling were randomized into model group, EA group, and donepezil treatment group (n=10). EA treatment was administered at the acupoints Baihui (GV20) and Shenting (GV24) with a disperse-dense wave (2/15 Hz, 1 mA, 30 min/day), and donepezil was given by gavage at 0.45 mg/kg. Both interventions lasted 28 days. Cognitive function of the rats was assessed using Morris water maze test, and neuronal pathologies were observed using HE and Nissl staining. GFAP-labeled astrocyte activation was assessed by immunohistochemistry, and astrocytic ultrastructure was examined with transmission electron microscopy. GFAP/p-NF-κB colocalization was detected by immunofluorescence staining. Hippocampal IL-1β, IL-6, and TNF-α levels were measured by ELISA, and the protein expression levels of C3, S100A10, TLR4, and MyD88 and the p-NF-κB/NF‑κB ratio were detected by Western blotting.

Results: Compared with the sham-operated rats, VD rats showed significant cognitive impairment, obvious neuronal disorganization and pyknosis in the hippocampus, excessive astrocyte activation, increased GFAP/p-NF‑κB colocalization, inflammatory cytokine levels and expressions of C3 and TLR4/MyD88/NF-κB pathway proteins, and decreased expression of S100A10. Treatment with EA and donepezil significantly improved the performance of the rats in Morris water maze test, alleviated neuronal injury, inhibited astrocyte overactivation and ultrastructural damage, reduced inflammatory cytokine levels, expressions of C3, TLR4, and MyD88 proteins and the p-NF-κB/NF-κB ratio, and increased the expression of S100A10 in the hippocampus.

Conclusions: EA at GV20 and GV24 improves cognitive impairment and attenuate neuroinflammation in VD rats possibly by inhibiting TLR4/MyD88/NF-κB signaling and regulating astrocytic A1/A2-like phenotypic imbalance.