AJP - Regulatory, Integrative and Comparative Physiology, Vol 245, Issue 3 379-R385, Copyright © 1983 by American Physiological Society
An investigation of the age-related deficits in the febrile response of the rabbit
A. V. Ferguson, L. Bauce, W. L. Veale and K. E. Cooper
The febrile response of the New Zealand White rabbit in animals less than 1
yr old was compared with that in 3-yr-old animals. A reduced febrile
response to both endotoxin and live bacteria injected intravenously was
observed in the older group of animals. Peripheral vasoconstriction was
observed, suggesting the drive to increase body temperature remained.
Plasma catecholamines increased significantly in both groups of animals
during fever. However, significantly greater increases in plasma
epinephrine were observed in the older animals. A significant deficit in
catecholamine-induced thermogenesis was observed in the older group of
rabbits. This deficit alone does not explain the reduced febrile response,
as beta-adrenergic blockade does not suppress the febrile response of young
animals. Thus it is suggested that the primary deficit resulting in a
reduced febrile response in the 3-yr-old rabbits is due to other
age-related changes in the thermoregulatory system.
