Morphine dependence and body temperature in rhesus monkeys.

Rectal temperature was recorded in monkeys restrained in primate chairs. Morphine dependence was produced by the s.c. administration of morphine (3.0 mg/kg) repeated every 6 hr. In nondependent monkeys, chair restraint produced a small fall in temperature (0.6 ± 0.1°C). In morphine-dependent monkeys placement in the restraining chair 3 to 7 hr after a regular injection of morphine precipitated falls in body temperature as large as 8°C. Body temperature returned to normal when morphine was administered. These hypothermic responses did not occur if the monkeys were placed in the restraining chair within the first 3 hr after morphine. Administration of 1.0 mg/kg of nalorphine to morphine-dependent monkeys, a dose which produced no change of body temperature in nondependent monkeys, precipitated a severe abstinence syndrome and a large hypothermia. This hypothermic effect of nalorphine could be demonstrated after only 1 week of morphine treatment. Nalorphine also produced hypothermia in ketobemidone-dependent monkeys.