Role of the dopamine D3 receptor in the core and shell of the nucleus accumbens in conditioned modulation of memory consolidation.

There is evidence suggesting that the effect of conditioned stimuli (CS) on memory consolidation is mediated by the dopamine D3 receptor (D3R). The current study explored the hypothesis that D3Rs located in the nucleus accumbens core (NAcC) and shell (NAcS) are involved in this effect. Therefore, using male Sprague-Dawley rats and the object recognition memory task, it was tested whether: 1) intra-NAcC or intra-NAcS infusions of the selective D3R antagonist SB-277011A (0, 1 and 4 μg/side) could block facilitation of memory consolidation by a CS stablished through optimal conditioning on a signaled active avoidance task; and 2) intra-NAcC or intra-NAcS infusions of the D3R agonist 7-OH-DPAT (0 and 10 μg/side) could enhance conditioned memory facilitation by a CS which was ineffective on its own due to suboptimal conditioning. It was found that both 1 and 4 μg/side SB-277011A blocked CS-induced modulation of object memory when infused in NAcC, but not in the NAcS. In contrast, 10 μg/side 7-OH-DPAT infused in the NAcS, but not in the NAcC, enhanced modulation of object memory by a CS that was ineffective by itself. Taken together, these results suggest complementary roles of NAcS and NAcC D3Rs under varying CS predictability conditions in modulation of memory consolidation.