Ethanol anapyrexia in rats

In the present series of experiments we tested whether ethanol decreases body temperature by impairing thermal regulation (poikilothermia) or by shifting the set point downwards. The central temperature of rats kept in a thermocline and the selected ambient temperature were recorded by telemetry. After an IP injection of 2 g/kg of ethanol the rats selected an ambient temperature 7 degrees C lower than the one they selected before the ethanol injection and 8 degrees C lower than the one selected by the same rats after saline injection. At the same time the central temperature decreased by 2.5 degrees C. After about 40 min the rats preferred warmer ambient temperatures and 10 min later the central temperature began to rise. When, after ethanol, the rats were kept at 30 degrees C the central temperature remained at the normal level. At 35-36 degrees C the central temperature of normal rats without ethanol rose, in 1 h, from 37 degrees C to 39.75 degrees C. The results suggest that ethanol hypothermia is due to a downward shift of the set point and, in fact, is an anapyrexia, a condition inverse to fever.