Abstract

Mohaddes Gisou, Rasi Soheila and Naghdi Nasser*

Leptin is a peptide hormone secreted by adipose tissue. Some studies have suggested that leptin may affect learning and memory. The hippocampus has been implicated in many learning and memory functions including spatial memory. The present study is scheduled to investigate the effect of intrahippocampal (IH) injection of different doses of leptin on spatial memory formation. 40 male rats were divided into 4 groups in our experiment: (1) sham (saline treated animals), and (2), (3), (4) intrahippocampal injection of 0.1, 0.5 and 1 µg doses of leptin respectively. All groups were trained in Morris water maze for two consecutive days. Learning parameters were compared among groups. Our results showed, there were significant differences of learning parameters between sham group and test groups in spatial learning. Lower dose of leptin improved spatial learning better than high dose. In conclusion, our findings indicate that leptin in the hippocampus is involved in memory processing in rat and suggests also that low levels of leptin may perform better.