Vagotomy modifies but does not eliminate the increase in body temperature following burn injury in rats

Introduction: Rats with burn injury to greater than or equal to 50% of the BSA demonstrate a significant increase in body temperature (TB) during light hours, and decrease of circadian variation in T-B This study investigated the hypothesis that part or all of the signal for increased T-B in rats with burn injury is transmitted to the central nervous system by way of afferent vagal fibers. Methods: Four groups of animals were studied: Burn-Sham Vagotomy; Control-Sham Vagotomy; Burn-Vagotomy and Control-Vagotomy. Anesthetized animals had bilateral subdiaphragmatic vagotomy (VagX) or sham VagX performed, and AM radio transmitters were implanted in the peritoneal cavity for the purpose of recording T-B and activity index (AI). Following a one week recovery period, burn animals received scald burns equal to 50.3 +/- 2.5% BSA. Results: The main effect of VagX upon T-B was a Small but significant reduction in T-B during dark hours. At least 87% of this decrease in post-burn T-B was also present for the control vagotomy group. Vagotomy had no effect on the increase in T-B for the burn groups during light hours. During dark hours, VagX significantly reduced T-B in burns and controls, and burn injury significantly reduced activity. Conclusions: One may speculate that afferent vagal signals are partially responsible for maintenance of T-B, with or without burn injury, and that the major signal for increase in T-B for animals with burn injury is not a neural one via afferent vagal pathways. (C) 1999 Elsevier Science Ltd and ISBI. All rights reserved.