Exercise Improves Orofacial Pain and Modifies Neuropeptide Expression in a Rat Model of Parkinson's Disease

Author(s)

Binda, Karina Henrique ; Chacur, Marucia ; Martins, Daniel Oliveira

• Document type: Journal article
• Source: NEUROTOXICITY RESEARCH; v. N/A, p. 12-pg., 2023-06-02.

Abstract

Pain is a common non-motor symptom of Parkinson's disease (PD), which often occurs in the early disease stages. Despite the high prevalence, it remains inadequately treated. In a hemi-parkinsonian rat model, we aimed to investigate the neurochemical factors involved in orofacial pain development, with a specific focus on pain-related peptides and cannabinoid receptors. We also evaluated whether treadmill exercise could improve orofacial pain and modulate these mechanisms. Rats were unilaterally injected in the striatum with either 6-hydroxydopamine (6-OHDA) or saline. Fifteen days after stereotactic surgery, the animals were submitted to treadmill exercise (EX), or remained sedentary (SED). Pain assessment was performed before the surgical procedure and prior to each training session. Pain-related peptides, substance P (SP), calcitonin gene-related peptide (CGRP), and transient receptor potential vanilloid type 1 (TRPV1) activation and cannabinoid receptor type 1 (CB1) and type 2 (CB2) were evaluated in the trigeminal nucleus. In order to confirm the possible involvement of cannabinoid receptors, we also injected antagonists of CB1 and CB2 receptors. We confirmed the presence of orofacial pain after unilateral 6-OHDA-injection, which improved after aerobic exercise training. We also observed increased pain-related expression of SP, CGRP and TRPV1 and decreased CB1 and CB2 in the trigeminal ganglion and caudal spinal trigeminal nucleus in animals with PD, which was reversed after aerobic exercise training. In addition, we confirm the involvement of cannabinoid receptors since both antagonists decreased the nociceptive threshold of PD animals. These data suggest that aerobic exercise effectively improved the orofacial pain associated with the PD model, and may be mediated by pain-related neuropeptides and cannabinoid receptors in the trigeminal system. (AU)

• FAPESP's process: 14/24533-0 - Photodynamic therapy in trigeminal neuralgia
• Grantee: Marucia Chacur
• Support Opportunities: Regular Research Grants
• FAPESP's process: 15/24256-0 - Study of the structures involved in orofacial pain and perspectives of combined treatment of low level laser and B vitamins in a model of trigeminal neuralgia
• Grantee: Daniel de Oliveira Martins
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 21/02897-4 - Effect of photobiomodulation treatment on mitochondrial dynamics: analysis of the dorsal root ganglion in a type 1 Diabetes mellitus model
• Grantee: Marucia Chacur
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/26821-1 - Effect of physical exercise on induced nociception in the Parkinson's Disease model in rats
• Grantee: Karina Henrique Binda
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 17/05218-5 - Effect of photobiostimulation on different peripheral neuropathies in rats.
• Grantee: Marucia Chacur
• Support Opportunities: Regular Research Grants