Effect of intracerebroventricular vasopressin on body temperature and endotoxin fever of macaque monkey.

In the adult monkey (Macaca fasicularis) acclimated to a primate restraint chair, intracerebroventricular (ICV) cannulas were stereotaxically implanted bilaterally in the lateral cerebral ventricle. During an experiment, colonic and skin temperatures were continuously recorded, and in selected cases heart and respiratory rates as well as O2 consumption were similarly monitored. Arginine vasopressin (AVP) was infused ICV in a volume of 500 microliter in one of six doses ranging from 16 to 4,240 ng. The results showed that AVP in all doses infused failed to alter the resting core and skin temperatures of the monkey or other recorded physiological responses. After a fever was produced in the monkey by 1/10-1/100 dilution of Escherichia coli endotoxin infused ICV, AVP at doses of 16-260 ng did not augment the febrile response. Further, AVP infused in the same range of doses caused only a negligible and inconsistent antipyretic action; i.e., the 65-ng dose of AVP lowered the mean core temperature of the febrile monkey by only 0.5 degrees C. This was in marked contrast to the antipyretic effect of dipyrone administered systemically. In addition, no reproducible changes occurred in respiratory, heart, or metabolic rates after ICV infusion of AVP. These results indicate that AVP does not affect the normal thermoregulatory function of this species of monkey and, in contrast to other species, a febrile response is neither enhanced nor antagonized in the monkey by a central action of AVP. Although AVP thus does not appear to be an endogenous antipyretic in the monkey, anatomic investigations will be required to substantiate this conclusion in the subhuman primate.