The influence of hypothalamic temperature on some thermoregulatory effects of hypothalamic injections of norepinephrine.

Bilateral injections of norepinephrine bitartrate (5.0-20.0 microng) into the preoptic region and anterior hypothalamus were always followed by a reduction in core temperature and rate of behaviorally obtaining radiant heat in cold-exposed (5 degrees C) squirrel monkeys regardless of whether the temperature of this region was experimentally raised (40-42 degrees C) or lowered (32-34 degrees C). Decreases in tail temperature following injections of norepinephrine indicated that vasoconstriction was also associated with the reduction in body temperature and behavioral responses. Since conflicting behavioral and autonomic responses are observed following injections of norepinephrine, it is suggested that norepinephrine may be affecting thermoregulatory effector pathways nonspecifically rather than altering the set point about which body temperature is regulated.