title: The neural mobilization technique modulates the expression of endogenous opioids in the periaqueductal gray and improves muscle strength and mobility in rats with neuropathic pain.
abstract: BACKGROUND
  The neural mobilization (NM) technique is a noninvasive method that has been proven to be clinically effective in reducing pain; however, the molecular mechanisms involved remain poorly understood. The aim of this study was to analyze whether NM alters the expression of the mu-opioid receptor (MOR), the delta-opioid receptor (DOR) and the Kappa-opioid receptor (KOR) in the periaqueductal gray (PAG) and improves locomotion and muscle force after chronic constriction injury (CCI) in rats.
  
  
  METHODS
  The CCI was imposed on adult male rats followed by 10 sessions of NM every other day, starting 14 days after the CCI injury. At the end of the sessions, the PAG was analyzed using Western blot assays for opioid receptors. Locomotion was analyzed by the Sciatic functional index (SFI), and muscle force was analyzed by the BIOPAC system.
  
  
  RESULTS
  An improvement in locomotion was observed in animals treated with NM compared with injured animals. Animals treated with NM showed an increase in maximal tetanic force of the tibialis anterior muscle of 172% (p < 0.001) compared with the CCI group. We also observed a decrease of 53% (p < 0.001) and 23% (p < 0.05) in DOR and KOR levels, respectively, after CCI injury compared to those from naive animals and an increase of 17% (p < 0.05) in KOR expression only after NM treatment compared to naive animals. There were no significant changes in MOR expression in the PAG.
  
  
  CONCLUSIONS
  These data provide evidence that a non-pharmacological NM technique facilitates pain relief by endogenous analgesic modulation.
authors.forename: Fabio Martinez
authors.initials: FM
authors.lastname: Santos
authors.forename: Leandro Henrique
authors.initials: LH
authors.lastname: Grecco
authors.forename: Marcelo Gomes
authors.initials: MG
authors.lastname: Pereira
authors.forename: Mara Evany
authors.initials: ME
authors.lastname: Oliveira
authors.forename: Priscila Abreu
authors.initials: PA
authors.lastname: Rocha
authors.forename: Joyce Teixeira
authors.initials: JT
authors.lastname: Silva
authors.forename: Daniel Oliveira
authors.initials: DO
authors.lastname: Martins
authors.forename: Elen Haruka
authors.initials: EH
authors.lastname: Miyabara
authors.affiliation: Department of Anatomy, Laboratory of Functional Neuroanatomy of Pain, Institute of Biomedical Sciences, University of São Paulo, Av, Prof, Lineu Prestes, 2415, São Paulo 05508-000 SP, Brazil. chacurm@icb.usp.br.
authors.forename: Marucia
authors.initials: M
authors.lastname: Chacur
mesh_terms: D000818:Animals; D008297:Male; D009068:Movement / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000503:physiopathology*; D009437:Neuralgia / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D010487:Periaqueductal Gray / Q000378:metabolism* / Q000503:physiopathology; D026741:Physical Therapy Modalities; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000378:metabolism*
chemical_list: D011957:Receptors, Opioid