Central temperature regulation in the conscious rabbit after monoamine oxidase inhibition.

1. Measured thermal loads were applied to conscious rabbits by intravenous infusions of hot or cold saline. The responses of the central temperature regulating mechanism were assessed by measuring hypothalamic temperature change. The relationship between thermal load and temperature response was established in normal animals.2. Intramuscular injection of tranylcypromine (20 mg/kg. day for 6-8 days) had no effect upon resting temperature or the temperature response to thermal loads, though the diencephalic concentrations of noradrenaline and 5-hydroxytryptamine (5-HT) were increased.3. Either hypothalamic monoamines are not concerned in the regulation of normal temperature or there is a monoamine ;pool' in the hypothalamus which is concerned with temperature regulation but which is unaffected by monoamine oxidase inhibition.