How Pain, Including Headache, Becomes Chronic.

The article presents several studies concerning headache. One of these studies aim to identify whether glial cells are involved in the mustard-oil induced central sensitization in trigeminal subnucleus caudalis (Vc) nociceptive neurons. Another one reveals the role of p38 mitogen-activated protein kinase (MAPK) (p38 MAPK) in the spinal cord as well as in development of chronic morphine antinociceptive tolerance. A review which illustrates the two roles of microglia and astrocytes is emphasized.