The effects of deep brain stimulation in neuropathic pain induced rats

Abstract

Neuropathic pain induced by peripheral nerve injury is clinically very common. High-frequency deep brain stimulation (DBS) is an effective treatment for chronic neuropathic pain, but the mechanisms underlying its analgesic effects are not precisely known. I investigated the mechanism of high-frequency DBS-related analgesia on neuropathic symptoms using male Sprague-Dawley rats with peripheral nerve injuries to induce neuropathic pain. Rats were divided into four groups, naive, naive + VPL-DBS, neuropathic pain, and neuropathic pain + VPL-DBS. Before and after VPL-DBS, c-fos and GAD65 in the prefrontal cortex, thalamus, and spinal dorsal horn were measured by western blot. In the neuropathic pain + VPL-DBS group, an analgesic effect was observed compared to the neuropathic pain group, and significant c-fos expressions was seen after VPL-DBS in the prefrontal cortex and thalamus. Also, the expressions of GAD65 in the neuropathic pain + VPL-DBS group was slightly higher in the spinal dorsal horn than in the neuropathic pain group, while c-fos expression was decreased. These results suggested that VPL-DBS exerts an effect at both the brain and spinal cord level. High-frequency DBS suppressed the hyper-excited neuronal activities, especially in the prefrontal cortex and thalamus area, and modulate the pain threshold by upregulation of GAD65 expression in spinal dorsal horn.