Normal body temperature of rats: The setpoint controversy

Emotional hyperthermia, circadian variations and the rise of body temperature related to exercise, have all been attributed to setpoint temperature shifts. The accepted theory holds that core temperature is regulated by corrective thermoregulatory responses opposing the core temperature deviations from the setpoint level. However, in fever and anapyrexia the thermoregulatory responses appear to be not corrective but helping, that is in the same direction as the core temperature deviation. A supplementary ad hoc hypothesis that setpoint level shifts explains why the thermoregulatory responses still could be considered "corrective" in spite of being in the same direction as the core temperature deviation. But supplementary ad hoc hypotheses immunize a theory to experimental challenges and therefore can no longer be considered a scientific theory. The present work shows that most of the arguments adduced to explain almost every biothermal phenomenon as being due to setpoint shifts cannot withstand a critical analysis. (C) 1998 Elsevier Science Ltd. All rights reserved.