AJP - Regulatory, Integrative and Comparative Physiology, Vol 257, Issue 1 150-R155, Copyright © 1989 by American Physiological Society
Fever response in laboratory-maintained and free-ranging chuckwallas (Sauromalus obesus)
A. E. Muchlinski, R. J. Stoutenburgh and J. M. Hogan
Department of Biology, California State University, Los Angeles 90032.
The fever response was studied in laboratory-maintained and free-ranging
chuckwallas. Five animals were used in a self-pairing laboratory experiment
in which each animal was first injected with a sterile, pyrogen-free saline
solution. Approximately 7 days later, each individual was injected with a
solution of 4.75 x 10(9) Aeromonas sobria (formerly A. hydrophila).
Saline-injected individuals had a mean preferred body temperature (MPBT) of
36.8 +/- 0.4 (SE) degrees C, whereas bacteria-injected animals had a MPBT
of 39.1 +/- 0.6 (SE) degrees C (an increase of 2.3 degrees C). The
within-animal variance associated with MPBT was significantly decreased in
bacteria-injected animals. In the natural environment, 10 chuckwallas were
divided into five pairs, so that both animals of a pair could be monitored
simultaneously. One animal in a pair was given an injection of sterile,
pyrogen-free saline, whereas the other animal received an injection of 4.75
x 10(9) A. sobria. On day 2, both the MPBT and the rate of heating were
greater in bacteria-injected animals. The between-animal variation in fever
MPBT was greater than the mean increase in MPBT of fever animals. Also, the
absolute level of the MPBT during the fever response was related to time of
the year, with spring-active animals having the highest fever MPBTs.
