A positive fever response by a poikilothermic mammal, the naked mole rat (Heterocephalus glaber)

1. 1.Heterocephalus glaber (the naked mole rat) is unique amongst mammals in that it is an endothermic poikilotherm. This unusual mode of thermoregulation leads one to question other thermoregulatory reactions such as the thermal response to pyrogens. 2. 2.The thermal component of the fever response of Heterocephalus glaber was investigated. Body temperature was measured following injections of a Gram-positive pyrogen (Staphylococcus aureus cell walls) and saline (n = 9). 3. 3.Injection with saline resulted in a 0.8 ± 0.2°C rise in temperature and a 4 h thermal response index of 1.5 ± 0.5°C · h. This is primarily attributed to handling stresses and was not different to the effects of handling without any injection. 4. 4.A significant monophasic fever developed 50min after S. aureus injection and was maintained until 190 min post-injection. Compared with pre-injection baseline measurements, the maximum change in temperature was 1.5 ± 0.2°C, and the 4 h thermal response index was 3.4 ± 0.5°C · h. After removing the apparent handling effects (as shown by the saline treatment) the pyrogen-induced elevation in body temperature was 0.7°C. 5. 5.This poikilothermic mammal can therefore endogenously elevate body temperature and shows a positive fever response to Gram-positive pyrogens.