Continuous systemic interleukin-1 alpha infusion suppresses food intake without increasing lateral hypothalamic dopamine activity

In addition to its immunomodulatory action, interleukin-1 (IL-1 alpha) induces anorexia centrally. Whether IL-1-induced anorexia is mediated by dopaminergic activity in the lateral hypothalamic area (LHA) was investigated by using microdialysis in freely moving rats. After recovery from jugular vein catheterization and LHA cannulation, rats had a microdialysis probe inserted into the LHA. Microdialysis samples were continuously collected in control rats not infused, and in IL-1-treated rats during and after a 24 h continuous systemic infusion of 6 micrograms IL-1 alpha. IL-1 alpha significantly suppressed food intake from 13.6 +/- 0.1 g to 4.3 +/- 0.8 g (p < 0.001), but there was no significant difference in dopamine concentration in the LHA dialysates before, during and after IL-1 alpha infusion relative to controls. Although IL-1 alpha has been shown to act centrally, our results suggest that the anorexic effect of IL-1 alpha is not mediated through dopaminergic activity in the LHA.