Fig. 1:

Housing guidelines for experimental mice regulate many environmental factors which affect the physiology of mice used in pre-clinical experiments; variations in these parameters can create differing degrees of stress. In the case of temperature, mice housed at standard sub-thermoneutral housing temperatures (22°C) are subjected to chronic cold-stress compared to mice housed at thermoneutral temperatures (30°C) and, although the body temperatures in both cases are normal, cold-stressed mice have elevated levels of norepinephrine. Thus these mice have a pre-existing level stress which is biologically significant and the effects of this stress on different experimental models is largely unknown.