Objectives: Osteoarthritis (OA) is a predominant pathology with aging and occurs mainly in women. OA is refractory to various forms of treatment and is accompanied by persistent inflammation. Noninvasive auricular vagus nerve (aVNS) stimulation has shown surprising results in the treatment of inflammatory conditions, including OA. Objective: To compare the effects of left and right ear aVNS at different times on mechanical hyperalgesia in an animal model of inflammatory pain.
Design: The study was approved by the ethics committee under No. 18.048.2.07.IV. Female Swiss mice (35-45g) submitted to intraplantar injection of Complete Freund's Adjuvant (CFA) were distributed (n = 8 animals / group) into the following groups: CFA + aVNS off 30'; CFA + aVNS 10', CFA + aVNS 20' and CFA + aVNS 30'. aVNS parameters were: Frequency (1) = 2 Hz; Pulse width (1) = 700 µs; Time (1) = 5 seconds; Resting time = 0. Frequency (2) = 10 Hz; Pulse width (2) = 200 µs; Time (2) = 5 seconds; Resting time = 0. Mechanical hyperalgesia was evaluated with von Frey monofilaments (0.6g) applied to the right hind paw at 6 and 96hs after CFA injection.
Results: The results showed that aVNS for 10 min induced better antihyperalgesic effect (p < 0.05) both at 6 and 96 hours after CFA injection, when compared to 20 min and 30 min stimulation.
aVNS for 10 min in the left ear was more effective in reducing mechanical hyperalgesia in both phases of the inflammatory profile induced by CFA intraplantar injection.
Afonso Salgado– Associate Researcher, University of Southern Santa Catarina
Daiana Cristina Salm– Professor, University of Southern Santa Catarina
Francisco Cidral Filho– Associate Researcher, University of Southern Santa Catarina - Brazil
Edsel Bittencourt– PhD Student, Mayo Clinic / Jacksonville
Bruna Hoffmann de Oliveira– Student, University of Southern Santa Catarina
Júlia Koerich– Student, UNISUL
Carlos Omura– Student, UNISUL
Rodolfo Parreira– PhD Student, Instituto Salgado
Lisandro Ceci– Student, UNISUL
Leidiane Martins– Doutora, UFSC
Ari Moré– Assistent Professor, UFSC
Daniel Fernandes Martins– Professor, University of Southern Santa Catarina