Involvement of dopamine D1 and D2 receptors in the rat nucleus accumbens in immunostimulation

Analysis of the nature of changes in the immune response in operated Wistar rats showed that electrolytic lesioning of the nucleus accumbens, the site of the greatest density of dopamine D₁ and D₂ receptors, led to suppression of the immune response in animals immunized with sheep erythrocytes. Administration of SKF 38393 (20 mg/kg) and quinpirol (1 mg/kg), selective agonists of dopamine D₁ and D₂ receptors respectively, to sham-operated rats induced significant increases in immune responses. However, no immunostimulation was seen on administration of the selective dopamine D₂ agonist quinpirol to animals with lesions to the nucleus accumbens as compared with controls. At the same time, treatment of animals with nucleus accumbens lesions using the dopamine D₁ receptor agonist SKF 38393 had no effect on the immune response as compared with that in sham-operated animals given the D₁ receptor agonist. These data provide evidence that dopamine D₂ receptors in the nucleus accumbens have a role in the mechanisms of immunostimulation, though D₂ receptors in other brain structures may also make some contribution to this process; D₁ receptors in the nucleus accumbens make no significant contribution to controlling the immune response. __________ Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 91, No. 11, pp. 1281–1287, November, 2005.