Abstract: Interleukin-1 is a key molecular factor involved in the process of brain-immune interactions. Many stressful stimuli may increase IL-1 bioactivity, and administering IL-1 produces sickness behavior. Peripherally released IL-1 acts on the brain via a fast transmission pathway involving primary afferent nerve innervating the bodily site of inflammation and a slow transmission pathway involving slowly diffusing IL-1 from the circumventricular organs and choroids plexus to brain targets.

Key words: interleukin-1, sickness behavior, stress response