It is conceivable that mediators of inflammation, like interleukin 1β, IL-6 and TNF-α, that are elevated in the brain of animals with acid saline-induced fibromyalgia [39] may activate IDO [40], which, in the presence of an excess of Trp, would lead to increased KYN levels in the brain. The gene discussed is TNF; the disease is fibromyalgia.