title: Expression of the dopaminergic D1 and D2 receptors in the anterior cingulate cortex in a model of neuropathic pain.
abstract: BACKGROUND
  The anterior cingulate cortex (ACC) has been related to the affective component of pain. Dopaminergic mesocortical circuits, including the ACC, are able to inhibit neuropathic nociception measured as autotomy behaviour. We determined the changes in dopamine D1 and D2 (D1R and D2R) receptor expression in the ACC (cg1 and cg2) in an animal model of neuropathic pain. The neuropathic group had noxious heat applied in the right hind paw followed 30 min. later by right sciatic denervation. Autotomy score (AS) was recorded for eight days and subsequently classified in low, medium and high AS groups. The control consisted of naïve animals.A semiquantitative RT-PCR procedure was done to determine mRNA levels for D1R and D2R in cg1 and cg2, and protein levels were measured by Western Blot.
  
  
  RESULTS
  The results of D1R mRNA in cg1 showed a decrease in all groups. D2R mRNA levels in cg1 decreased in low AS and increased in medium and high AS. Regarding D1R in cg2, there was an increase in all groups. D2R expression levels in cg2 decreased in all groups. In cg1, the D2R mRNA correlated positively with autotomy behaviour. Protein levels of D2R in cg1 increased in all groups but to a higher degree in low AS. In cg2 D2R protein only decreased discretely. D1R protein was not found in either ACC region.
  
  
  CONCLUSIONS
  This is the first evidence of an increase of inhibitory dopaminergic receptor (D2R) mRNA and protein in cg1 in correlation with nociceptive behaviour in a neuropathic model of pain in the rat.
authors.affiliation: Laboratorio de Neurofisiología Integrativa, Dirección de Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente, México.
authors.forename: J Manuel
authors.initials: JM
authors.lastname: Ortega-Legaspi
authors.forename: Patricia
authors.initials: P
authors.lastname: de Gortari
authors.forename: René
authors.initials: R
authors.lastname: Garduño-Gutiérrez
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Amaya
authors.forename: Martha
authors.initials: M
authors.lastname: León-Olea
authors.forename: Ulises
authors.initials: U
authors.lastname: Coffeen
authors.forename: Francisco
authors.initials: F
authors.lastname: Pellicer
mesh_terms: D000818:Animals; D015870:Gene Expression; D006179:Gyrus Cinguli / Q000378:metabolism*; D008297:Male; D009437:Neuralgia / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017447:Receptors, Dopamine D1 / Q000235:genetics* / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000235:genetics* / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2