STRESS HYPERTHERMIA - PHYSIOLOGICAL ARGUMENTS THAT IT IS A FEVER

The theory that stress (or emotional) rise in central temperature (T(c)) in rats is a fever with an upward shift of the set-point temperature was tested with three experiments: 1) Measurement of tail skin temperature and T(c) during the emotional T(c) rise; 2) Investigation of the effect of ambient temperature on the emotional T(c) rise; and 3) The assessment of emotional T(c) rise during daytime and nighttime. Skin vasomotor responses helped the increase of T(c) toward a higher level and contributed to the regulation of central temperature at this new higher level. The cold environment did not diminish the emotional rise of central temperature as it would be expected in the case of a hyperthermia. However, at night emotional fever reached a higher level than during the daytime, suggesting that prostaglandin rise in T(c) is distinct from emotional or stress-induced hyperthermia. In conclusion, the experiments reported here confirm the hypothesis that the rise of T(c) induced by handling or disturbance of the rats is regulated, and is due to a shift of the set-point as occurs in fever.