title: Altered synaptic transmission in rat anterior cingulate cortex following peripheral nerve injury.
abstract: BACKGROUND
  Patients with neuropathic pain present not only with persistent pain but also a complex set of additional symptoms, including mood disorders and cognitive disturbance. Given the important roles of the anterior thalamic nuclei (ATN) and anterior cingulate cortex (ACC) in the cognitive and emotional aspects of pain, investigation of the properties of ATN-ACC synapses will help us to understand the mechanisms underlying neuropathic pain.
  
  
  METHODS
  We studied changes in ATN-evoked ACC excitatory postsynaptic potentials (EPSPs) induced by neuropathic pain in a rat model under halothane anaesthesia.
  
  
  RESULTS
  Neuropathic pain caused significant suppression of EPSPs in the ACC compared with rats subjected to sham surgery. Similar to previous evidence, acute inflammatory pain induced by formalin injection into the hind paw significantly increased synaptic efficacy in the ACC compared with naive rats. Neither of the pain paradigms altered the paired-pulse responses.
  
  
  CONCLUSIONS
  A possible explanation for the neuropathic pain-related suppression of EPSPs is that the ACC was already sufficiently active at baseline as a result of neuropathic pain, and ATN stimulation could not further increase the already elevated level of ACC activity. This abnormal excitability of the ATN-ACC synapse may be important in understanding the mechanism underlying neuropathic pain, particularly with respect to the affective and cognitive aspects.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan. shibak@med.hokudai.ac.jp
authors.forename: Kaori
authors.initials: K
authors.lastname: Tachibana
authors.forename: Rui
authors.initials: R
authors.lastname: Kato
authors.forename: Kenkichi
authors.initials: K
authors.lastname: Tsuruga
authors.forename: Koichi
authors.initials: K
authors.lastname: Takita
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Hashimoto
authors.forename: Yuji
authors.initials: Y
authors.lastname: Morimoto
mesh_terms: D000818:Animals; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D006179:Gyrus Cinguli / Q000503:physiopathology*; D008026:Ligation; D008297:Male; D009437:Neuralgia / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000293:injuries / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology*