Obese mice Neotomodon alstoni show learning impairment in Morris Water Maze test, differences between midday and midnight

Abstract

ABSTRACT Spatial memory and information retention are affected by the obesity condition and the time of day evaluated at the Morris Water Maze test Neotomodon alstoni. A group of animals was studied in a first trial at noon or midnight for four consecutive days, and memory retention was tested at the fifth and the 15th day. One month later, the same mice were evaluated with the same protocol in the opposite phase of the photoperiod that first time. Results show that lean mice achieve a shorter latency than obese mice to find the platform in the test during the first trial, without being clear the differences between midday and midnight. In the second trial, lean mice show a shorter latency time at night than during the day, while obese mice show longer latency times without nictemeral differences. Lean mice spent more time in the quadrant where the platform was located. We conclude that there is a remarkable deficit in obese mice when analysed in Morris Water Maze, and that subtle differences can be observed between day and night between groups.