Interleukin-1 induces conditioned taste aversion in rats: a possible explanation for its pituitary-adrenal stimulating activity.

To investigate the possible aversive stimulus properties of peripherally administered interleukin 1 (IL-1), rats received two pairings of ingestion of a saccharin solution with various doses of recombinant rat interleukin 1 in a conditioned taste aversion paradigm, using 20 mg/kg lipopolysaccharide endotoxin as a positive control. Rats treated with 1 and 10 micrograms IL-1 showed a dose-dependent reduced preference for saccharin together with dose-dependent impairments in weight gain. Since these effects were obtained within the range of doses that has been previously reported to stimulate the release of ACTH, it is proposed that this last action of IL-1 is likely to be secondary to the aversive effects of IL-1.