Interleukin-1 Beta Has Excitatory Effects on Neurons of the Bed Nucleus of the Stria Terminalis

Arginine vasopressin (AVP) is an endogenous antipyretic which acts in the ventral septal area (VSA) of the brain following its release from terminals of neurons from the bed nucleus of the stria terminalis (BST). The neurochemical mechanisms involved in the activation of these BST neurons are unknown. The present study was conducted to determine whether a naturally occurring brain cytokine (interleukin-1 beta, IL-1) selectively activates the population of BST neurons projecting to the VSA or another locus known to receive vasopressinergic input from the BST, the habenular nuclei (HAB). Single unit extracellular recordings were made from identified BST neurons in urethane-anesthetized rats. Human recombinant IL-1 applied iontophoretically or by micropressure, evoked marked excitations of long duration in 24% of all BST cells observed (n = 102 cells). Iontophoresis of sodium salicylate attenuated or reversed the effects of the cytokine in all cases tested. The selective and long-lasting excitatory actions of IL-1 on BST neurons are consistent with a direct CNS function for this cytokine. In addition, these results are compatible with a role for IL-1 in evoking AVP release from BST neurons during fever.