Effects of waiting time between trials and water temperature on cognitive functions, body temperature and body weight in rats in Morris water maze

Abstract

The Morris water maze (MWM) is a widely used test among neurobiologists to measure spatial memory. The implementation of this test carries the risk of hypothermia periods in animals. The level of hypothermia may affect age-related memory processes as a significant factor. The occurrence of hypothermia throughout the MWM protocol should be better understood as hypothermia may impair memory performance. Ensuring the standardization of the experiments and minimizing side effects require a detailed examination of the hypothermia-related processes. Our study aims to replicate and extend the data of previous studies in terms of determining the possible species-specific variations and provide data for reorganizing the time intervals. In this study, rats (Wistar Hannover) were used and grouped according to the differences in the inter-trial interval (ITI) (30-s and 13-min) and water temperatures (20 °C and 24 °C). The effects of ITI and water temperature on probe performance were analysed statistically (mixed two-way ANOVA). Results showed that the 13 minute waiting group of animals performed statistically better in the MWM probe phase compared to the 30 second waiting group. The prolongation of ITI between the tests was found to have a positive impact on the memory performance. Longer ITI should be preferred instead of the frequently used 30-60 second test intervals. Thus, animals will be exposed to less stress and more reliable results can be obtained, also possible side effects of hypothermia can be minimized while performing the MWM test.