Cm. Deen et Vh. Hutchison, Effects of lipopolysaccharide and acclimation temperature on induced behavioral fever in juvenile Iguana iguana, J THERM BIO, 26(1), 2001, pp. 55-63
We examined the effects of acclimation temperature and two doses (2.5 and 2
5 mg kg(-1)) of a pyrogen (lipopolysaccharide, LPS) on behavioral thermoreg
ulation in juvenile green iguanas. Overall means of body temperatures for t
he three-day trial periods were compared among three groups of animals accl
imated at 15, 25, and 34 degreesC. The responses of each group of animals t
o the two dosages of LPS and a control saline injection were examined. With
in each treatment block, animals either chose high body temperatures charac
teristic of a fever response or chose low body temperatures characteristic
of a hypothermic response. Thermoregulation was influenced by interaction e
ffects between and among, and independent effects of, acclimation temperatu
re, dose of LPS, and day. In some treatment blocks, individual lizard mass
positively correlated with mean individual body temperature. Mean mass of l
izards that chose higher body temperatures within a treatment block was hig
her than the mean mass of lizards that chose lower body temperatures. From
these results, we concluded that LPS may induce two different behavioral th
ermoregulatory responses: fever or hypothermia. The actual amplitude and di
rection of body temperature change appears to be affected by acclimation te
mperature and possibly by mass or energy reserves of the animal. If the ene
rgy reserves an not sufficient to sustain the higher rate of metabolism ass
ociated with the higher body temperatures of a hyperthermic or feverish sta
te, the animal may resort to hypothermia. (C) 2001 Elsevier Science Ltd. Al
l rights reserved.