Morphine is an opioid and a mu opioid receptors agonist that effects memory and learning processes and causes memory impairment. In this investigation, involvement of the ventral tegmental area (VTA) in effects of ghrelin on morphine induced amnesia were studied. 28 male wistar rats were tested and divided in to 4 groups. Surgery and cannulation in the VTA were performed in animals of control group and experimental groups. The control group immediately received intracranial saline training and received subcutaneous morphine (7.5 mg/kg) 5 minutes after training. Intravenous ghrelin injection in the second, third and fourth groups were administrated systemically (0.3-1.5-3 nmol/ µl)5 minutes before injection of morphine to investigate the role of ghrelin on morphine memory and behavioral testing. Subcutaneous injection of morphine (7.5 mg/kg) was performed after induction of amnesia and behavioral tests and animals` memory was examined with passive avoidance test. The statistical analysis was performed using one-way analysis and spss software. Ghrelin (3 nmol/µl) injection significantly (P<0.0001) increased memory retention in the VTA compared to the control group. Thus ghrelin can to increase the activity of dopamine neurons, synaptic formation and memory improvement by binding to its receptors on neurons in the region of the VTA.
