Alteration of Nociceptive Integration in the Spinal Cord of a Rat Model of Parkinson's Disease

Background: Pain is a major non motor symptom that contributes to impaired quality of life in PD. However, its mechanism is unknown. Objectives and Methods: We sought to identify the pain phenotypes and parallel changes in spinal integration of peripheral stimuli in a rat model of PD induced by lesions of SN dopamine neurons, using behavioral plantar and von Frey tests as well as electrophysiology of the dorsal horn. Results: We show that dopamine depletion by 6-OHDA induced hypersensitivity to mechanical and thermal stimuli. These abnormal behaviors were paralleled by increased neuronal responses and hyperexcitability of wide dynamic range neurons of lamina V of the dorsal horn of the spinal cord in response to electrical stimulation of the sciatic nerve in the 6-OHDA model as compared to sham rats. Conclusions: These results provide evidence for alteration of nociceptive integration in the spinal dorsal horn neurons in 6-OHDA rats that can reflect changes in pain behavior. (C) 2018 International Parkinson and Movement Disorder Society