Chronic indomethacin administration blocks increased body temperature after burn injury in rats

This study investigates the hypothesis that continuous administration of indomethacin (a cyclo-oxygenase inhibitor) will chronically reduce body temperature (TB) in burned rats (i.e., modulate "true" fever). Male Sprague-Dawley rats had radio transmitters and osmotic pumps (containing indomethacin) placed in the peritoneal cavity, and 7 days later large full-thickness scald burns were produced. Activity and TB were continually recorded through the 14th postburn day (PBD). There were 4 experimental groups: burn + indomethacin (B-In), n = 9; burn + polyethylene glycol (B-Peg), n = 6; control + indomethacin (C-In), n = 9; and control + polyethylene glycol (C-Peg), n = 6. From PBD 5 through PBD 10, the B-Peg group had consistently and significantly higher TB during light hours than the B-In, C-In, and C-Peg groups. From PBD 7 through PBD 12, the B-In group had an average TB during light hours significantly lower or not different than the C-In and C-Peg groups. These results support the hypothesis that in this burned-rat model chronically increased TB during the light hours may be "fever" (rather than hyperthermia) and that the final effector link could be a prostanoid because changes in activity do not explain the changes in body temperature.