Increasing evidence has suggested that cholecystokinin (CCK) is involved in immune-to-brain communication. The afferent vagus nerve is an important component for transmitting peripheral immune signals to the brain, such as those determining interleukin (IL)-1beta expression in the brain and anorexia. In the present study, we investigated whether the anorexic effect of CCK, which also activates the afferent vagus nerve, is mediated via IL-1beta expression in the brain. CCK-8 dose-dependently (8-320 microg/kg, i.p.) inhibited food intake in mice. However, IL-1beta transcripts in the hypothalamus, the hippocampus and the brainstem were not significantly increased after the administration of CCK-8, even at the larger dose of 320 microg/kg. These findings suggest that the CCK-induced inhibition of food intake may be independent of IL-1beta production in the brain, and indicate the diverse role of CCK in the regulation of the neuro-immune interaction.