Antinociceptive effects of treadmill exercise in a rat model of Parkinson's disease: The role of cannabinoid and opioid receptors

Author(s)

Binda, K. H. ^[1] ; Real, C. C. ^[2] ; Ferreira, A. F. F. ^[3] ; Britto, L. R. ^[3] ; Chacur, M. ^[1]

Affiliation

^[1] Univ Sao Paulo, Dept Anat, Lab Funct Neuroanat Pain, Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Fac Med, Lab Nucl Med LIM 43, Sao Paulo, SP - Brazil

^[3] Univ Sao Paulo, Dept Physiol & Biophys, Lab Cellular Neurobiol, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Brain Research; v. 1727, JAN 15 2020.
• Web of Science Citations: 0

Abstract

In addition to motor symptoms, Parkinson's disease (PD) presents high prevalence of painful symptoms responsible for worsening quality of life of PD patients. Physical exercise can improve such painful symptoms. This study evaluated the effects of exercise on nociceptive threshold using an unilateral rat model of PD, as well as the role played by cannabinoid and opioid receptors in areas responsible for pain pathways. For PD induction, Wistar rats were injected with 6-OHDA. 15?days after, rats either remained sedentary or were forced to exercise three times a week for 40 min. Motor and nociceptive behaviors were evaluated through cylinder and mechanical hyperalgesia tests, respectively. The animals were euthanized for analysis of cannabinoid receptor type 1 (CB1) and type 2 (CB2), and mu-opioid receptor (MOR) in the anterior cingulate cortex (ACC), periaqueductal gray matter (PAG), and thalamus areas by immunohistochemistry (IHC) and Western blotting. Our data revealed a decrease in the nociceptive threshold in both forepaws after surgery; in contrast, there was improvement in painful symptoms after the exercise protocol. For cannabinoid system there were an increase in CB2 expression in the ACC and PAG, and in CB1 levels in the PAG. And for opioid system there was an increase of MOR expression in the thalamus. Thus, modulation of those receptors by physical exercise can be an important non-pharmacological intervention to reduce painful symptoms in a rat model of PD, contributing to knowledge and promotion of better treatment aimed at improving the quality of life of PD patients. (AU)

• FAPESP's process: 17/05218-5 - Effect of photobiostimulation on different peripheral neuropathies in rats.
• 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