Interleukin-1 induces c-Fos immunoreactivity in primary afferent neurons of the vagus nerve

Peripheral administration of bacterial endotoxin, an immune stimulant, induces evidence of activation in vagal primary afferent neurons. To determine whether interleukin-1 beta (IL-1 beta) is part of the molecular pathway leading to this activation, we assessed the expression of the neuronal activation marker c-Fos in vagal primary afferent neurons after intraperitoneal injections of IL-1 beta (2 mu g/kg). IL-1 beta, but not vehicle, induced c-Fos expression, demonstrating that IL-1 beta is likely an important signal from the immune system to the vagus nerve, and thus the brain. (C) 1998 Published by Elsevier Science B.V. All rights reserved.