Behavioral determination of the preferred foot pad temperature of the mouse

Most thermoregulatory research in rodents focuses on air temperature (T-air) and its effects on convective, radiative, and evaporative heat loss. On the other hand, the foot pad temperature (T-fp), which is influenced by conductive heat exchange with the floor, is also thought to be important in driving behavioral and autonomic thermoeffectors. In this study the role of T-fp and T-air on behavioral thermoregulation was assessed by constructing an automated system which measured the selected floor temperature (T-f(s)) of mice placed on a copper floor with a temperature gradient. Drawing air through slots in the floor allowed T-air to be kept nearly constant. The frequency distribution of T-f(s) of female CD-1 mice was measured over 2 h periods in the gradient T-air at of 25-40 degrees C. Mean T-f(s) was similar to 34.5 degrees C and the mode ranged from 33 to 37 degrees C at T-air of 30-35 degrees C. Mean T-f(s) decreased at a T-air of 40 degrees C. There was a paradoxical reduction in T-f(s) at T-air of 25 and 27.5 degrees C. The measurement of T-f(s) as a function of T-air allows one to discern the role of T-fp on thermoregulatory control. Moreover, it can be used to assess peripheral neuropathies resulting from exposure to neurotoxicants. Published by Elsevier Science Ltd.