Therapeutic effects of repeated transcranial acupuncture stimulation on facial nerve compression injury-induced facial paralysis in rats via Janus kinase-signal transducer and activator of transcription pathway activation

Abstract

Background

Facial nerve injury is a neurological condition that involves paralysis or weakness of the facial muscles. Repeated transcranial acupuncture stimulation (rTAS) is a specialized acupuncture technique that has shown effectiveness in clinical studies for treating facial nerve paralysis; however, its underlying mechanisms are incompletely understood. We aimed to clarify the therapeutic effects and mechanisms of rTAS on facial nerve compression injury-induced facial paralysis in rats.

Methods

Fifty rats were divided into five groups (n = 10 per group): control group (CG), model group (MG), and three rTAS groups: 0-min repeated transcranial acupuncture stimulation group (rTAS-0), 2-min repeated transcranial acupuncture stimulation group (rTAS-2), 5-min repeated transcranial acupuncture stimulation group (rTAS-5). The MG and rTAS groups underwent facial nerve compression to model paralysis, whereas CG underwent nerve exposure only. The rTAS groups then received acupuncture (30 min daily for 14 days) with varying twisting and rest durations. We assessed facial function, temperature, and electrophysiology, followed by serum and facial nerve collection for hematoxylin and eosin, Nissl, and Masson's staining, and for immunohistochemistry, enzyme-linked immunosorbent assay, and reverse transcription polymerase chain reaction to explore nerve repair factors.

Results

Compared with the CG, the MG showed reduced facial function, prolonged latency and decreased amplitude of compound muscle action potentials, and more severe nerve injury, including lower Nissl body counts and collagen fiber ratios (p < 0.05). rTAS treatment alleviated facial nerve damage; rTAS-5 exhibited the greatest effects, with improved facial function, nerve activity, and electrophysiological indices and reduced pathological scores. rTAS-5 also enhanced histological features such as Nissl body density and collagen fiber ratios (p < 0.05). Moreover, rTAS-5 upregulated JAK1 and STAT3 expression in the facial nerve, suggesting activation of the JAK/STAT pathway during the repair process.

Conclusions

rTAS may improve facial function in rats with facial paralysis, and a longer twisting time might yield better results. Our findings suggest that rTAS increases JAK1 and STAT3 expression to activate the JAK/STAT pathway, thereby promoting the regeneration and repair of damaged nerves.