VPL-DBS on neuropathic pain rat model is effective in mechanical allodynia than cold allodynia

Recently, deep brain stimulation (DBS) is widely used in various types of neurodegenerative disorders for minimal invasiveness and safety of the procedure. Deep brain stimulation is consistently applied for the treatment of patients with neuropathic pain even though the success rate is not as high as other neurodegenerative disorders. Furthermore, it is also unclear how DBS improves neuropathic pain. In this study, we investigated the role of DBS following the stimulation parameter for analgesic effect on mechanical allodynia and cold allodynia in neuropathic pain rats. We used a sciatic nerve injury model to induce neuropathic pain, and observed responses to mechanical and cold stimulation by the von Frey test and acetone test, respectively. We classified the rats into four groups: naïve (naïve, n = 10), naïve + DBS (N + DBS, n = 10), neuropathic pain (NP, n = 10), and neuropathic pain + DBS (NP + DBS, n = 10). We inserted the DBS electrode into the ventral posterolateral nucleus (VPL) into the rats (VPL-DBS). The score for mechanical allodynia was significantly decreased in NP + DBS group (p<0.01). However, the score for cold allodynia did not significantly drop in any groups including NP + DBS group (p>0.05). In this study, we found that the electrical stimulation of the VPL works more effectively with mechanical allodynia than cold one, and pain signal induced by mechanical stimulus and cold stimulus may be processed through different pathways in the brain.