Anorexia, weight loss and increased plasma interleukin-6 caused by chronic intracerebroventricular infusion of interleukin-1β in the rat

Pro-inflammatory cytokines produced in the central nervous system (CNS) have been suggested to have a role in the anorexia and cachexia of disease. In the present study, the effects of chronic exposure of the CNS to interleukin-1 β (IL-1β) on several indicators of cachexia were studied. Rats were prepared with an intracerebroventricular (i.c.v.) cannula and an osmotic minipump that delivered vehicle or 1.56 ng/h recombinant murine IL- 1 β for 4 days. Food intake and body weight were determined daily during the 4-day infusion period and plasma IL-6 and corticosterone concentrations were determined from plasma collected postinfusion. Chronic i.c.v. infusion of IL-1β resulted in a chronic reduction in food intake. Rats infused i.c.v. with IL-1β ate less food each day compared to vehicle controls and, at the end of the 4-day infusion period, consumed an average of 17.2 g less. Intracerebroventricular infusion of IL-1β also caused an immediate and substantial loss of body weight that was sustained throughout the infusion period. In addition, rats infused with IL-1β had plasma levels of IL-6 double those of vehicle controls (401 pg/ml vs. 185 pg/ml). Plasma corticosterone concentrations were similar between treatments. These results suggest that chronic exposure of the CNS to cytokines such as IL-1β may be sufficient to induce anorexia and cachexia.