Hypothermia produced by peripheral and central injections of chlorpromazine in aged rabbits

Hypothermia produced by IV administration of chlorpromazine (CPZ, 0.5-2.0 mg/kg) in a thermoneutral environment was greater in rabbits 2-4.5 years old than in animals under 24 months of age. One microgram CPZ given intracerebroventricularly (ICV) produced greater hypothermia in the older animals in tests performed in a thermoneutral environment while 0.25 and 0.5 microgram doses did not. The hypothermogenic effect of all three ICV doses of CPZ was enhanced in older rabbits exposed to cold. The brain of the older rabbit appears to be more sensitive to the hypothermogenic effects of CPZ. The findings suggest that this widely used tranquilizer can contribute to accidental hypothermia of the aged.