Stress-induced hyperthermia in the rat: comparison of classical and novel recording methods

Stress causes a rise in body temperature in laboratory animals (stress-induced hyperthermia). However, the direct effect of common stressors in animal research, i.e. transportation between holding and test rooms or isolation of animals, on body temperature has not been investigated to its full extent. To address this question, it is important to have a reliable and simple monitoring technique, which does not induce stress itself. In the present study, we investigated stress-related changes in body temperature of F344/Hw rats after (1) moving the cage within the holding room, (2) moving the cage from the holding room to another test room and (3) social deprivation (isolation). A combination of two different body temperature recording methods was used to clarify their accuracy and stress-inductive character: rectal temperature recording and peritoneal implanted temperature sensors (Thermochron iButtons). The results demonstrate that (1) different stressors induce a significant rise in body temperature, (2) which is detectable for more than 60 min and (3) it is of importance to standardize temperature recording methods in order to avoid confounding effects of the recording method itself. Furthermore, Thermochron iButtons are more accurate and reliable for body temperature studies than rectal recordings.