Central mediation of the effects of interleukin-1 on social exploration and body weight in mice

To study the role of central IL-1 receptors in the effects of recombinant human IL-1 beta (IL-1 beta) on behavior and body weight, intracerebroventricular (ICV) injection of the specific antagonist of IL-1 receptors, IL-1ra, was administered to mice injected intraperitoneally (IP) and ICV with various doses of IL-1 beta. Doses of 500 ng IP IL-1 beta and 900 pg ICV IL-1 beta induced a comparable decrease in social behavior and loss of body weight. Pretreatment with IL-1ra (1.8 mu g/mouse, ICV) blocked the effects of ICV IL-1 beta (900 pg/mouse) on social behavior. ICV IL-1ra (3.6 mu g/mouse) also attenuated the effects of IP IL-1 beta (500 ng/mouse) on social behavior and change in body weight, suggesting that the effects of peripheral IL-1 beta are centrally mediated. (C) 1997 Elsevier Science Ltd.