Introduction: Ghrelin is a peptide mainly produced by the stomach and released into the circulation, affecting energy balanced and growth hormone release. It is well know that learning and memory in labratory animals can be affected by ghrelin treatment.the extensive evidence that the hippocampus is involved in the learning and the memory. In this study we examined the involvement of the hippocampus on ghrelin effects on morphine induced memory impairment in male rats. Materials and Methods: The experimental groups consist of control group, morphine groups and treated groups with morphine + ghreline. A single trial step through passive avoidance task was used for the assessment of memory retention in male wistar rats. animals were bilaterary cannulated in the CA1 by stereotaxic instrument,and were allowed to recover for one week before behavioral testing. Results:post-training subcutaneous administration of different doses of morphine (0.5, 2.5, 5, 7.5 mg/kg) dose dependently decreased the learning and induced amnesia. Intra-CA1 injection of ghrelin (0.03, 0.3, 3 nmol) 5 minutes before the injection of effective dose of morphine (7.5 mg/kg) dose dependently restored the memory retieval (p<0.0001). Discussion: The results suggested that learning and memory can effecte by ghrelin. Intra-hippocampal ghrelin administration after training improved morphine-induced memory impairment.
