The effect of melatonin and luzindole on spatial learning and memory in rats treated with darkness

Background: During critical periods of growth, evolution dependent of sensory experience has a deep effect on the formation and proper function of mammal’s CNS. The aim of this study is to assess the interaction of melatonin and its antagonist, luzindole on rat’s spatial learning and memory processes treated in darkness using the Morris Water Maze (MWM). Materials and Method: This experimental study was carried out on 60 Wistar male rats of 45 days which randomly distributed in two groups. Animals of the control group experienced 12 hour-periods of darkness & light and the test group developed in complete darkness. Each group has 3 subgroups: Control, receiving Melatonin and receiving Luzindole (n=10 for each). Using MWM, the learning process and memory consolidation of animals were evaluated for 5 nights and 4 times each night. Results: The results of this study showed that the learning stage in animals deprived of light phase needed more time to find the platform than the control group (p=0.011). Also, melatonin can increase this time in the control rats (p=0.012). Darkness treatment and melatonin were not effective on memory consolidation of these animals. Luzindole in control rats needed less time spending in the target quadrant (p=0.009).Conclusion: Darkness treatment causes impairment in spatial learning process in rats and melatonin will make it difficult spatial learning in control animals. None of the above two interventions are effective on the process of memory consolidation