To test the possible role of biogenic amines as neurotransmitters in thermoregulation, norepinephrine, epinephrine, 5-HT, and dopamine were infused into the anterior hypothalamus or third ventricle of the brain of conscious baboons. Norepinephrine infused at 1 µg/min for 15 min evoked cutaneous vasodilation, bradycardia, hypotension, and a 1.2°C (SE) fall in mid-brain temperature (Tmb), used as an index of core temperature, within 1 h (p