Role of D1- and D2-like dopamine receptors within the dentate gyrus in stress- and morphine-induced reinstatement in the food-deprived rats

Background and Aim : The high rate of relapse to drug abuse is one of the main problems in the treatment of addiction. Stress plays an essential role in relapse to the drug. In the present study, we evaluated the role of dopamine receptors (D1- and D2-like) and compared their activities in the dentate gyrus (DG) region, focusing on the reinstatement induced by the food deprivation stress (FDS) and a sub-threshold dose of morphine (0.5 mg/kg, s.c.).Methods : The animals received different doses of SCH23390 or sulpiride (0.25, 1 and 4 μg/0.5 μl vehicle), as D1- and D2-like dopamine receptors antagonist respectively, into the DG, on the 8th day of the extinction. After the administration of the antagonists, they were placed in stress circumstances of food deprivation for 24h and conditioning scores were measured on reinstatement day.Results : Our results showed that the administration of SCH23390 and sulpiride dose-dependently attenuated the extinguished morphine- CPP reinstated by FDS and morphine. The behavioral results were more prominent in the groups of animals that received SCH23390 as compared to sulpiride.Conclusion : In conclusion, these results show that D1- and D2-like dopamine receptors in the DG area are involved in reinstatement induced by FDS and a sub-threshold dose of morphine and these receptors are might be as a potential target for addiction treatment.

Keywords:

Reward , Stress , Dopamine receptors , Dentate gyrus , Reinstatement , Food deprivation , Conditioned place preference , Rat