AJP - Regulatory, Integrative and Comparative Physiology, Vol 265, Issue 6 1351-R1354, Copyright © 1993 by American Physiological Society
Tumor necrosis factor is not involved in exercise-induced elevation in core temperature
P. J. Rowsey, K. T. Borer and M. J. Kluger
Division of Kinesiology, University of Michigan, Ann Arbor 48109.
Female Sprague-Dawley rats (12:12-h light-dark photoperiod) with access to
running wheels have an elevated body temperature (BT) both during exercise
(nighttime) and nonexercise periods (daytime). We studied whether the
exercise-induced increase in BT is modulated by the release of the
cytokine, tumor necrosis factor-alpha (TNF). Two weeks after the onset of
exercise, nighttime temperatures of exercising rats were elevated
approximately 0.5 degree C compared with preexercise values (P = 0.006). By
3 wk after the onset of exercise, daytime temperatures had increased 0.3
degree C (P = 0.03) above control levels. To confirm that endogenously
produced TNF can modulate fever in female rats, we injected six rats with
antiserum to TNF (300 microliters/rat) and six rats with control serum 24 h
before intraperitoneal injection of lipopolysaccharide (50 micrograms/kg).
As occurred in earlier studies on male rats, antiserum-treated female rats
had significantly enhanced fevers (P = 0.017). To determine whether
endogenously produced TNF was involved in modulating the daytime and
nighttime increases in BT, antiserum to TNF (300 microliters/rat, n = 7) or
control serum (300 microliters/rat, n = 5) was injected intraperitoneally
in exercising rats. Neither injection of antiserum nor control serum had
any effect on daytime or nighttime BTs. Because BTs of exercising female
rats injected with antiserum against TNF were not affected, we conclude
that TNF is not responsible for modulating their exercise-induced rise in
BT.
