Chronic pain is a major complaint for up to 85% of Parkinson Disease patients, however, often not identified as a symptom of Parkinson’s disease. Adequate treatment of motor symptoms often provides analgesic effects in Parkinson’s patients, how this occurs remains unclear. Studies have shown both Parkinson’s patients and 6-hydroxydopamine lesioned rats exhibit decreased sensory thresholds. In humans, some show improvements in these deficits after subthalamic deep brain stimulation, while others report no change. Differing methods of testing and response criteria may explain these varying results. We examined this effect in 6-hydroxydopamine lesioned rats. Sprague dawley rats were unilaterally implanted with subthalamic stimulating electrodes in the lesioned right hemisphere and sensory thresholds were tested using vonFrey, tail flick and hot plate tests. Tests were done during and off subthalamic stimulation at 50 and 150Hz to assess its effects on sensory thresholds. 6-hydroxydopamine lesioned animals exhibited lower mechanical (left paw, p<0.01) and thermal thresholds than shams (hot plate, p<0.05). Both 50 and 150Hz increased mechanical (left paw; p<0.01) and thermal thresholds in 6-hydroxydopamine lesioned rats (HPT; 150Hz, p<0.05, 50Hz, p<0.01). Interestingly, the magnitude of improvement in mechanical thresholds during LFS was similar between animals, whereas during HFS was much more diverse. This study shows that subthalamic deep brain stimulation improves mechanical allodynia and thermal hyperalgesia in 6-hydroxydopamine lesioned animals at both high and low frequencies. Furthermore, we suggest considering using low frequency stimulation when treating Parkinson’s patients where pain remains the predominant complaint.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.