Chemokine-induced fever: intracerebroventricular actions of MIP-1 and MIP-1 alpha in rats.

The central pyrogenic actions in the rat of doublet macrophage inflammatory protein-1 (MIP-1) and MIP-1 alpha were determined by their intracerebroventricular infusion. Doses of 560 pg and 11.2 ng of MIP-1 or 10.0 ng MIP-1 alpha infused into the third cerebral ventricle induced a long lasting fever. However, MIP-1 alpha was much less potent than MIP-1 in terms of intensity and longer latency. Overall, these cytokines are pyrogenic when acting on the walls of the third ventricle; however, a dose 10 times greater than that injected directly into the anterior hypothalamus is required to evoke fever, as based on earlier experiments. Finally, circulating MIP-1 could act centrally by its entry through the choroid plexus into the ventricular system of the brain.