Effect of cervical vagotomy on sympathetic nerve responses to peripheral interleukin-1β

Although the vagus nerve is an important neural pathway mediating immune-to-brain communication, the role of the vagus in mediating sympathetic nerve discharge (SND) responses to peripheral cytokines is not well established. In the present study we determined renal, interscapular brown adipose tissue (IBAT), splenic, and lumbar SND responses before and for 60 min after the intravenous administration of interleukin-1β (IL-1β, 100 ng) in chloralose-anesthetized, sham-vagotomized and cervical-vagotomized (bilateral) rats. In sham-vagotomized rats, IL-1β administration increased (P<0.05) splenic and lumbar SND while renal and IBAT SND remained unchanged from control levels. Renal, splenic, and lumbar SND were increased (P<0.05) whereas IBAT SND remained unchanged from control after IL-1β in vagotomized rats. Renal, splenic, and lumbar SND responses were significantly higher after IL-1β in vagotomized compared with sham-vagotomized rats. These results demonstrate that regionally-selective SND (renal, splenic, and lumbar) responses to IL-1β can occur in the absence of the vagus nerve and suggest that the vagus nerve provides a tonic inhibition to the discharges in these nerves in response to peripheral IL-1β.