Chemicals that cause inflammation may be responsible for the throbbing pain of a migraine headache, according to Harvard researchers. They reported in Nature that experiments on rats show that nerves and blood vessels associated with the meninges, or membranes between the brain and skull, are highly sensitive to naturally occurring chemicals in the body.
Andrew Strassman and his colleagues cut open the skulls of rats, exposing the nerves in the meninges. They irritated these nerves with salt solution, capsaicin, which gives hot peppers their bite, and "a soup of inflammatory agents" such as histamine, the hormone serotonin and a prostaglandin. The nerves reacted strongly, which would probably translate to severe pain such as that seen in a headache.