TDK conference 2018

Noise can alter normal phyisology in mammals leading to behavioural changes and can be used as a variable in scientific studies. Laboratory mice which are universally used in scientific research are known to be sensitive to environmental disturbances highlighting the importance of generating the least possible external variables on research specimens. A near genetically identical batch of laboratory mice can display significant phenotypic variability when exposed to environmental factors. Our study was conducted to investigate the effects of exposure to a variety of everyday noises on two main groups of laboratory mice, namely noise-acclimatised (desensitized) compared to noise sensitive (non- acclimatised), in order to distinguish behavioural responses. We used 26 SPF (specified pathogen-free) CD1 laboratory mice, randomly divided into four groups: control males, control females, treated males, treated females. ‘Treated’ groups were exposed to a combination of sounds other than used in the final experiment. Behaviour of experimental individuals was assigned to the following groups: glancing, grooming, sniffing, moving on all fours, rearing, sitting. Each individual was also evaluated in terms of location during the experiments as follows: corner of the cage, middle of the cage, side (edge) of the cage. We further investigated the brains of 24 of our laboratory mice subjects following euthanasia, to determine the presence of any noticeable physiological changes. We found that in general, the effects of noise on the behaviour of the mice were not clearly significant. Exceptions were (a) Week 2, control males spent significantly more time in the middle of the cage than the other three groups and (b) also Week 2, significant differences occurred between control males and control females in terms of sniffing behaviour. Significant differences were also regularly noted among treated females in terms of rearing behaviour. Histopathological examination of brain and other tissues did not indicate significant effects, however, brain tissue samples from the desensitized groups displayed modification of lipidperoxidation, resulting in less free radicals in the brains of treated female mice compared to control females, while there was no difference between control and noise acclimatised males. This could be a considerable implication since male mice are predominantly used in scientific experiments. We suggest that reducing background noise levels in laboratory experiments is important and that laboratory animal holding facilities should be designed and built with the intention of generating the minimum of environmental noise.