Microinjections of GABA(B) receptor antagonist into the lateral habenula suppress the acquisition and expression of conditioned place preference induced by morphine in rats

Background and Aim : The habenula divided into lateral and medial regions. The lateral habenula (LHb) plays an important role in the reward circuit. LHb neurons are predominantly glutamatergic and convey negative reward information to the ventral tegmental area (VTA) dopaminergic neurons through an intermediary structure, GABAergic rostromedial tegmental nucleus (RMTg). In the recent study, effects of bilateral injection of GABAB receptor antagonist into the LHb on the acquisition and expression of morphine-induced conditioned place preference(CPP) in male rats have been studiedMethods : In this study using adult male Wistar rats as subjects and were divided into groups (n = 6). We investigated the influence of microinjection of GABAB receptor antagonist, phaclofen (0.5–2 μg/rat) into the LHb with ineffective and effective dose of morphine (0.5 and 5 mg/kg, respectively) on acquisition and expression of CPP induced by morphine in male rats.Results : Subcutaneous injection of different doses of morphine sulphate (0.5–7.5mg/kg) induced a dose-dependent CPP. Using a 3-day schedule of conditioning, we found that microinjection of phaclofen (0.5–2 μg/rat) into the LHb decreased the acquisition and expression of CPP induced by morphine that this indicates defects in the learning and memory formation with a significant place aversion.Conclusion : Our data indicated that the GABAB receptors of the LHb may play an active role in the acquisition and expression of morphine-induced CPP

کلیدواژه ها:

morphine ، cpp ، phaclofen ، lateral habenula ، VTA