Interleukin-6 in the aging brain.

Astrocytes, microglia, and neurons express the cytokine interleukin-6 (IL-6), which in the brain has been suggested to reduce food intake, inhibit memory and learning, cause neurodegeneration, and exacerbate sickness behavior induced by other cytokines. Recent evidence indicates IL-6 levels are increased in brain of healthy aged animals, thus it may play a role in the neurophysiological manifestations of old age. The purpose of this brief report is to discuss the new evidence that suggests an age-related increase in brain IL-6 and the impact this inflammatory cytokine may have on "successful" aging.