Abstract Objective Vagus nerve stimulation (VNS) has been shown to improve chronic pain, including fibromyalgia, migraine headaches, and gastrointestinal pain, as well as inflammation in rheumatoid arthritis. Here, we investigated the efficacy of transcutaneous VNS (tVNS) in providing pain relief in a mouse model of post-traumatic osteoarthritis (PTOA). Methods Destabilization of the medial meniscus (DMM) surgery was performed in 16-week-old female and male mice. Beginning at 4 weeks post-injury, mice were randomized to receive tVNS (10 minutes daily, 5 days per week) delivered via the tragus of the ear or sham stimulation for 8 weeks. Mechanical hyperalgesia, as measured using an algometer, and weight distribution were monitored at three time points: (1) pre-VNS, (2) 4-week treatment, and (3) 8-week treatment (end point of study). Results Compared to sham treatment, 4 weeks of tVNS reduced mechanical hyperalgesia in female mice, and eight weeks of tVNS improved weight-bearing in male and female mice. tVNS altered serum pro-inflammatory cytokine and chemokine levels in a sex-dependent manner. Eight weeks of tVNS improved the lateral femur compartment of the DMM-affected joints in males. Conclusion Our results reveal that tVNS improves PTOA-related pain and suppresses pro-inflammatory cytokine production, making it a promising, non-addictive intervention for chronic OA pain.
Yadav et al. (Thu,) studied this question.