Augmented interleukin-1beta-induced depression of locomotor activity in cholestatic rats.

"Sickness behaviors" such as lethargy, fatigue, and malaise occur commonly in patients with cholestatic liver diseases and contribute significantly to the morbidity associated with these diseases. However, the cause of these symptoms is unknown. Interleukin-1beta (IL-1beta) released within the brain has been implicated in the genesis of a number of "sickness behaviors," including malaise and lethargy. Therefore, we investigated whether experimental cholestatic liver disease caused by bile duct resection (BDR) in rats is associated with enhanced central sensitivity to IL-1beta-induced "sickness behaviors." The central infusion of IL-1beta at a dose that produced an insignificant decrease in locomotor activity in control rats produced a striking reduction in locomotor activity in cholestatic rats. The anorectic response to central IL-1beta infusion was similar in cholestatic and noncholestatic animals and did not parallel our locomotor activity findings. Therefore, cholestatic liver injury is characterized by augmented central responsiveness to IL-1beta with respect to a decrease in locomotor activity. These findings may explain, at least in part, the high incidence of symptoms such as fatigue, malaise, and lethargy that occur in cholestatic patients and may open novel future avenues for their treatment.