title: Endogenous dopamine release induced by repetitive transcranial magnetic stimulation over the primary motor cortex: an [11C]raclopride positron emission tomography study in anesthetized macaque monkeys.
abstract: BACKGROUND
  Repetitive transcranial magnetic stimulation (rTMS) has been used as a treatment for neuropsychiatric disorders such as depression and Parkinson's disease (PD). Despite the growing interest in therapeutic application of rTMS, precise mechanisms of its action remain unknown. With respect to PD, activation of the mesostriatal dopaminergic pathway is likely to be a candidate mechanism underlying the therapeutic effects; however, modulating effects of rTMS over the primary motor cortex (M1) on the dopaminergic system have not been studied.
  
  
  METHODS
  We used [11C]raclopride positron emission tomography to measure changes of extracellular dopamine concentration after 5Hz rTMS over the M1 in eight anesthetized monkeys.
  
  
  RESULTS
  rTMS over the right M1 induced a reduction of [11C]raclopride binding potential (BP) in the bilateral ventral striatum, including the nucleus accumbens, and a significant increase of BP in the right putamen; no significant BP reduction was found in the dorsal striatum. These data indicate that rTMS over the motor cortex induces a release of endogenous dopamine in the ventral striatum.
  
  
  CONCLUSIONS
  Our results suggest that therapeutic mechanisms of rTMS may be explained in part by an activation of the mesolimbic dopaminergic pathway, which plays critical roles in rewards, reinforcement, and incentive motivation.
authors.affiliation: Department of Investigative Radiology, National Cardio-Vascular Center Research Institute, Osaka, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohnishi
authors.forename: Takuya
authors.initials: T
authors.lastname: Hayashi
authors.forename: Shingo
authors.initials: S
authors.lastname: Okabe
authors.forename: Ikuo
authors.initials: I
authors.lastname: Nonaka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsuda
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Iida
authors.forename: Etsuko
authors.initials: E
authors.lastname: Imabayashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Watabe
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Miyake
authors.forename: Mikako
authors.initials: M
authors.lastname: Ogawa
authors.forename: Noboru
authors.initials: N
authors.lastname: Teramoto
authors.forename: Yoichirou
authors.initials: Y
authors.lastname: Ohta
authors.forename: Norimasa
authors.initials: N
authors.lastname: Ejima
authors.forename: Tohru
authors.initials: T
authors.lastname: Sawada
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Ugawa
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D002421:Caudate Nucleus / Q000000981:diagnostic imaging / Q000378:metabolism / Q000528:radiation effects; D004298:Dopamine / Q000378:metabolism* / Q000528:radiation effects; D018492:Dopamine Antagonists / Q000493:pharmacokinetics; D004565:Electroconvulsive Therapy / Q000295:instrumentation / Q000379:methods; D004574:Electromagnetic Fields; D008252:Macaca fascicularis; D008297:Male; D009044:Motor Cortex / Q000528:radiation effects*; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000378:metabolism / Q000528:radiation effects; D009714:Nucleus Accumbens / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000528:radiation effects; D011699:Putamen / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000528:radiation effects; D020891:Raclopride / Q000493:pharmacokinetics; D014055:Tomography, Emission-Computed; D050781:Transcranial Magnetic Stimulation / Q000627:therapeutic use
chemical_list: D002250:Carbon Radioisotopes; D018492:Dopamine Antagonists; D020891:Raclopride; D004298:Dopamine