Environmental enrichment: Music, day and dusk, how do they influence the rat's behaviour in laboratory (Rattus norvegicus)?

A great deal of studies show that many factors such as noise, light, presen ce of human beings can disturb the physiology and the behaviour of animal t hat are housed and manipuled in laboratory, in modifying their welfare stat e. According to some authors, to house animals in an enriched environment i ncreases their ability to adapt to the environment and lowers their level o f stress and emotion in new situations. The aim of the study here presented and carried out in the animal house of the Sanofi-Synthelabo centre is to determine the influence of the reproduct ion of dawn and dusk as well as the presence of temporary music in the hous ing room on the rat's behaviour at various moments said to be stressful for it. The results show that the enriched environment decreases the rat's rea ctivity in housing rooms but has only little influence when rats are taken out to be manipulated and has no influence on the results obtained during a n anxiety test (Elevated Plus-Maze).