Further observations on the suppression of fever in rabbits by intracerebral action of anisomycin.

1. Anisomycin has been given into the cerebral ventricles of rabbits. The inhibitory action of a range of doses on fever and on [14C]leucine incorporation into hypothalamic protein has been studied. 2. Fever was far less sensitive to inhibition by anisomycin than was incorporation of [14C]leucine. The dose--response curves showed a general similarity in shape, which would be compatible with the hypothesis that protein synthesis may be necessary for the production of fever. 3. A comparison was made of the effects of giving anisomycin into the cerebral ventricles 0, 30 or 60 min after the intraventricular injection of leucocyte pyrogen. Anisomycin inhibited fever to some extent even when given 60 min after leucocyte pyrogen. This suggests that if protein synthesis is involved in fever, it may continue at least into the early phase of rising temperature, but probably not to any significant extent after the plateau has been reached.