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

Introduction: Rats with burn injury to ≥50% of the BSA demonstrate a significant increase in body temperature (TB) during light hours, and decrease of circadian variation in TB. This study investigated the hypothesis that part or all of the signal for increased TB 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 TB 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 TB was a small but significant reduction in TB during dark hours. At least 87% of this decrease in post-burn TB was also present for the control vagotomy group. Vagotomy had no effect on the increase in TB for the burn groups during light hours. During dark hours, VagX significantly reduced TB in burns and controls, and burn injury significantly reduced activity. Conclusions: One may speculate that afferent vagal signals are partially responsible for maintenance of TB, with or without burn injury, and that the major signal for increase in TB for animals with burn injury is not a neural one via afferent vagal pathways.