Investigation of the effect of electrical stimulation of the lateral habenula on the acquisition and expression of conditioned place preference induced by morphine in rats

Background and Aim: The lateral habenula (LHb) has known as a potential location for interference in reward processes. LHb is an epithelial structure and plays an important role in regulating the midbrain monoaminergic system, through the fasciculus retroflexus (FR). LHb receives inputs from basal ganglia and limbic forebrain structures containing the lateral preoptic area and the lateral hypothalamus through the stria medullaris. LHb neurons generally contain excitatory glutamatergic and have great inhibitory connections with VTA dopaminergic neurons through an intermediate construction, GABAergic rostromedial tegmental nucleus (RMTg). In the recent study, effects of electrical stimulation (۲۵, ۷۵, ۱۵۰ μA) of the LHb on the acquisition and expression of morphine-induced conditioned place preference (CPP) in male rats have been studied. Methods: Stimulating electrodes were stereotaxically inserted into the LHb in anesthetized rats. We studied the influence of electrical stimulation of the LHb with ineffective and effective doses of morphine (۰.۵ and ۵ mg/kg, respectively) on acquisition and expression of CPP induced by morphine in male rats. Results: In this study male Wistar rats used. Subjects received doses of morphine (۰.۵, ۱.۵, ۲.۵, ۵, ۷.۵ mg/kg) subcutaneously or saline (۱.۰ ml/kg). Conclusion: The electrical stimulation of LHb (۲۵, ۷۵, ۱۵۰ μA) in combination with effective and ineffective doses of morphine exhibited a significant decrease only on acquisition phase that indicates deficits in the learning formation with a significant place aversion. Conclusion in this study proved that the electrical stimulation LHb may play a dynamic role in the acquisition of morphine-induced CPP.

Keywords:

morphine , cpp , electrical stimulation , lateral habenula , VTA