Transcranial direct‐current stimulation reduces nociceptive behaviour in an orofacial pain model

Abstract

Background: Transcranial direct-current stimulation (tDCS) is a noninvasive method of brain stimulation suggested as a therapeutic tool for pain and is related to the reversal of maladaptive plasticity associated with chronic pain.Objectives: This study investigated the effect of tDCS, a non-pharmacological therapy, on local mechanical hyperalgesia, and remote thermal hyperalgesia in rats submitted to orofacial inflammatory pain model, by facial von Frey and hot plate tests, respectively. In addition, we evaluated levels of BDNF, NGF, IL-10 and IL-6 in the brainstem and blood serum of these animals at 24 hours and 7 days after the end of tDCS treatment. Methods:Rats were subjected to temporomandibular joint pain and treated with tDCS. The animals were divided into control, pain and pain + treatment groups.Mechanical and thermal hyperalgesia were evaluated at baseline, 7 days after administration of complete Freund's adjuvant, and immediately, 24 hours, and 7 days after the tDCS treatment. Neuroimmunomodulators levels were determined by ELISA.Statistical analyses were performed by (GEE)/Bonferroni (behavioural tests), threeway ANOVA/SNK (neurochemical tests) and Kruskal-Wallis (histological analysis).Results: Transcranial direct-current stimulation reduced mechanical and thermal hyperalgesia (P < 0.01). We observed interaction between factors (pain and treatment) increasing brainstem BDNF (P < 0.01) and NGF (P < 0.05) levels. Furthermore, we found an increase in IL-6 and IL-10 levels in the brainstem at 24 hours and 7 days after tDCS, respectively. Conclusion:We showed that tDCS reduces thermal and mechanical hyperalgesia induced by orofacial pain until 7 days after treatment. These findings demonstrate that tDCS was effective in the control of orofacial inflammatory pain. K E Y W O R D S hyperalgesia, neuromodulation, orofacial inflammatory pain, tDCS, temporomandibular joint | 41 SCARABELOT ET AL. How to cite this article: Scarabelot VL, de Oliveira C, Medeiros LF, et al. Transcranial direct-current stimulation reduces nociceptive behaviour in an orofacial pain model.

Changes in Experimental Pain Sensitivity from Using Home-Based Remotely Supervised Transcranial Direct Current Stimulation in Older Adults with Knee Osteoarthritis

“…The current study provides preliminary evidence that tDCS is effective for improving QST measurements in individuals with knee OA. These results are consistent with the limited number of previous studies supporting the role of tDCS for improving QST measurements [26,42,43], primarily in individuals with a variety of chronic pain conditions other than knee OA (e.g., central poststroke pain [44]; orofacial pain [45]; fibromyalgia, chronic migraine, and neuropathic pain [46,47]).…”

Neuroinflammatory effects of tDCS in ovariectomized rats with chronic inflammation

“…Also, chronic systemic inflammation promoted neuroinflammation mainly induced by IL-1β-positive microglia in female rats 44 . A previous study by our research group showed that CFA-induced orofacial pain increased brainstem IL-6 levels and decreased brainstem IL-10 levels, suggesting that the pain model induced an imbalance in the inflammatory system regarding the structure analyzed 45 . Altogether these studies highlight that peripheral CFA injection induces a response of inflammatory signaling in the peripheral and central nervous system.…”

Effects of transcranial direct current stimulation (tDCS) on pro-inflammatory cytokines: a systematic review

“…The first reported study was published in 2012 (Spezia Adachi et al, 2012) (Table 1). Eight of the nine studies were developed by the same research group at the Federal University of Rio Grande do Sul (Callai et al, 2019;De Oliveira et al, 2019;Scarabelot et al, 2019;Cioato et al, 2016;Lopes et al, 2020;Spezia Adachi et al, 2012;Regner et al, 2020;Santos et al, 2020). All nine were scientific articles published in well-known journals, in English, with a predominance of three published in the Journal Brain Stimulation (Spezia Adachi et al, 2012;Cioato et al, 2016;Lopes et al, 2020).…”

“…Seven studies used bimodal stimulation (Table 1) (Callai et al, 2019;De Oliveira et al, 2019;Scarabelot et al, 2019;Cioato et al, 2016;Lopes et al, 2020;Regner et al, 2020;Santos et al, 2020) and two article used anodal current (Spezia Adachi et al al., 2012;Guo et al, 2020). In addition, the electrode position varied: seven articles used the area between the parietal cortex hemispheres (Scarabelot et al, 2019;Callai et al, 2019;Regner et al, 2020;Lopes et al, 2020;Santos et al, 2020;Cioato et al, 2016;Spezia Adachi et al, 2012), one study on the prefrontal cortex (De Oliveira et al, 2019), and one reported the application on the skullcap (Guo et al, 2020).…”

“…Eight studies used currents of 0.5 mA for 20 minutes (Table 2) (Callai et al, 2019;De Oliveira et al, 2019;Scarabelot et al, 2019;Cioato et al, 2016;Spezia Adachi et al, 2012;Lopes et al, 2020;Regner et al, 2020;Santos et al, 2020) and one study applied a current of 200 uA for 30 minutes (Guo et al, 2020). The treatments consist of 8 (Callai et al, 2019;De Oliveira et al, 2019;Scarabelot et al, 2019;Cioato et al, 2016;Spezia Adachi et al, 2012;Lopes et al al., 2020;Santos et al, 2020) or 10 tDCS sessions (Guo et al, 2020;Regner et al, 2020) Most studies used the current intensity of 0.5mA and 20 minutes of application time. Several models were applied to study the effects of tDCS, including nerve and vascular manipulation.…”