Prevention and suppression of pyrogenic fever in rabbits by hyperbaric oxygen

Current investigation was to determine whether hyperbaric oxygen had an effect on the febrile responses to systemic administration of lipopolysaccharide. An intravenous dose of lipopolysaccharide (2 microg/kg) caused an increase in core temperature accompanied by both plasma tumor necrosis factor-alpha and hypothalamic prostaglandin E(2) overproduction in rabbits. Administering hyperbaric oxygen (100% at 253 kPa) but not normobaric oxygen (100% at 101 kPa), once a day for consecutive 7 days prior to or 1 h after injecting lipopolysaccharide significantly reduced the lipopolysaccharide-induced elevation of both core temperature and circulating tumor necrosis factor-alpha. As compared to those of the simultaneous administration of normobaric air and lipopolysaccharide, administering hyperbaric oxygen or air plus lipopolysaccharide simultaneously had lesser febrile effects in terms of core temperature elevation, tumor necrosis factor-alpha overproduction and hypothalamic prostaglandin E(2) accumulation. However, the febrile responses produced by simultaneous application of normobaric oxygen plus lipopolysaccharide were not significantly different from those of normobaric air plus lipopolysaccharide. The results indicate that hyperbaric oxygen, and to some extent hyperbaric air, may cause prevention and suppression of pyrogenic fever by reducing overproduction of both circulating tumor necrosis factor-alpha and hypothalamic prostaglandin E(2).