Dopamine receptors in the anterior insular cortex modulate long‐term nociception in the rat

The rostral agranular insular cortex (RAIC) receives dopaminergic projections from the mesolimbic system, which has been involved in the modulation of nociceptive processes. In this study we determined the contribution of dopamine D₁ and D₂ receptors in the RAIC regarding nociception processing in a neuropathic pain model, as well as inflammatory articular nociception measured as pain‐induced functional impairment in the rat (PIFIR). Microinjection of vehicle or substances into the RAIC was performed after the induction of nociception. The groups were treated with: a dopamine D₁ receptor antagonist (SCH‐23390), a dopamine D₁ receptor agonist (SKF‐38393), a dopamine D₂ receptor agonist (TNPA) and a dopamine D₂ receptor antagonist (spiperone). Chronic nociception, induced by denervation, was measured by the autotomy score in which onset and incidence were also determined. The SCH‐23390 and TNPA groups showed a decrease in the autotomy score and a delay on the onset as compared to control, whereas the PIFIR groups did not show statistical differences. This work shows the differential role of dopamine receptors within the RAIC in which the activation of D₂ or the blockade of D₁ receptors elicit antinociception.