Hippocampal D1- but not D2-like receptors modulate the phosphorylation of ERK in food deprivation-induced reinstatement of morphine in extinguished rats

Background and Aim : Reinstatement to drug abuse is the most challenging issue in the addiction field so comprehensive knowledge of the involved neurobiological mechanisms is a fundamental necessity. It is known that dopamine is complicated in the neurobiology of numerous psychiatric diseases, including addiction and it is being considered a crucial element in the brain reward system.Methods : Our behavioral results documented that the administration of dopamine receptor antagonists inhibited reinstatement of morphine in FD rats. Previous studies present the ERK pathway plays a critical role in the control of cellular responses to stress and reward. Therefore, the purpose of this study was to evaluate the effect of intra-DG administration of dopamine receptors antagonists on the phosphorylation of hippocampal ERK in the reinstatement of morphine in FD rats.Results : All groups of animals passed conditional place preference (CPP) and were bilaterally given different doses of D1- or D2-like dopamine receptors, (0.25, 1 and 4 g/0.5 l) into the DG. Each animal was immediately killed after the reinstatement phase and its hippocampus was immediately dissected out and then, p-ERK/ERK ratio was evaluated by using Western blot analysis in the DG region.Conclusion : The principal findings in this study demonstrated that intra-DG administration of the highest dose of D1 receptor antagonist could enhance the hippocampal pERK/ERK ratio in FD rats while D2 receptor antagonist failed to change this ratio.

کلیدواژه ها:

Conditioned place preference ، Dentate gyrus ، Dopamine receptor ، Food deprivation ، pERK/ERK ratio ، Reinstatement