title: Endocannabinoid mechanism for orofacial antinociception induced by electroacupuncture in acupoint St36 in rats.
abstract: BACKGROUND
  This study was conducted with the aim of evaluating whether electroacupuncture (EA) at acupoint St36 could produce antinociception through the activation of an endocannabinoid mechanism.
  
  
  METHODS
  Male Wistar rats were divided into experimental groups. Heat was applied to the faces of rats, and the latency to withdraw the face was measured. Furthermore, the influence of electrical stimulation (100HzP) of acupoint St36, at a 0.5mA intensity, was investigated in the facial withdrawal threshold.
  
  
  RESULTS
  The EA produced antinociception, which lasted for 180min. This effect was antagonized by the pre-injection of AM 251, a CB1cannabinoid receptor antagonist, but not by AM 630, a CB2cannabinoid receptor antagonist. Additionally, pretreatment with an endocannabinoid metabolizing enzyme inhibitor (MAFP) and an anandamide reuptake inhibitor (VDM11) prolonged and intensified the antinociceptive effect produced by EA.
  
  
  CONCLUSIONS
  This study demonstrated for the first time that the CB1 cannabinoid receptor participates in the antinociceptive effect induced by EA.
authors: Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors: Renato Teixeira
authors: RT
authors: Almeida
authors: Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors: Thiago Roberto Lima
authors: TR
authors: Romero
authors: Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors: Marina Gomes Miranda E Castor
authors: MG
authors: Romero
authors: Department of Physiotherapy, Federal University of Alfenas, Alfenas, Minas Gerais, Brazil.
authors: Giovane Galdino
authors: GG
authors: de Souza
authors: Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors: Andrea de Castro
authors: AC
authors: Perez
authors: Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil. Electronic address: dimitri@icb.ufmg.br.
authors: Igor Dimitri Gama
authors: ID
authors: Duarte
mesh_terms: D015669:Acupuncture Points; D000818:Animals; D063386:Cannabinoid Receptor Agonists / Q000494:pharmacology / Q000627:therapeutic use; D063387:Cannabinoid Receptor Antagonists / Q000494:pharmacology / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D015671:Electroacupuncture / Q000379:methods*; D063388:Endocannabinoids / Q000378:metabolism*; D005157:Facial Pain / Q000378:metabolism* / Q000628:therapy*; D007211:Indoles / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods*; D010880:Piperidines / Q000494:pharmacology / Q000627:therapeutic use; D011720:Pyrazoles / Q000494:pharmacology / Q000627:therapeutic use; D051381:Rats; D017208:Rats, Wistar
chemical_list: D063386:Cannabinoid Receptor Agonists; D063387:Cannabinoid Receptor Antagonists; D063388:Endocannabinoids; D007211:Indoles; D010880:Piperidines; D011720:Pyrazoles; C103505:AM 251; C094023:iodopravadoline
keywords: Acupoint St36; Antinociception; Electroacupuncture; Endocannabinoid system; Orofacial nociception