Interleukin-1beta reduces temperature sensitivity but elevates thermal thresholds in different populations of...

Extracellularly recorded firing rates of neurons in slices of the preoptic area and anterior hypothalamus (PO/AH) of the rat were determined during thermal stimulation. Human recombinant interleukin-1beta (20 ng/ml) did not influence temperature-insensitive neurons, but reduced the firing rate and thermosensitivity in linear warm-sensitive neurons, and shifted the thermal thresholds of activation in threshold warm- and cold-sensitive neurons by 1.1-2.3 degrees C to hyperthermic temperatures. The data support the suggestion that endogenous pyrogens may act on different populations of thermosensitive PO/AH neurons to induce fever. The shift of the thermal thresholds of activation of threshold warm- and cold-sensitive neurons in combination with the otherwise maintained temperature sensitivity of these neurons appears to play a major part for the controlled shift of body temperature and the maintenance of the elevated body temperature during cytokine-induced fever.