Researchers know what causes endometriosis, but how the cysts that are characteristic of the disease maintain themselves and produce severe pain in some women has remained a mystery.
New research led by Florida State University Professor of Neuroscience Karen Berkley indicates that endometrial cysts develop their own nerve supply that could contribute both to the pain symptoms and the body's ability to maintain the disease.
"The new nerves likely sprout from those that supply the blood vessels that grow along with and nourish the cysts," Berkley said. "It has been well known that the cysts need a blood supply to survive. It also has been well known that blood vessels have their own nerve supply. Surprisingly, no one before us had put the two ideas together - that the cysts would be supplied by nerves that grow and extend from those that supply the cyst's blood vessels."
Berkley and colleagues Natalia Dmitrieva and Kathleen Curtis, both of FSU, and Raymond Papka, of Northeastern Ohio Universities College of Medicine, drew the conclusion after studying rats with surgically induced endometriosis. Their findings will be published in the Proceedings of the National Academy of Sciences journal.
The researchers transplanted small pieces of the rats' uteruses into their abdomens to produce cysts similar to those found in women with endometriosis. When the full-grown cysts were later removed, Berkley and her colleagues found that the cysts had become supplied by two main types of nerves, sensory and sympathetic. The sensory nerves are a type that transmits information about inflammation and injury from the cysts to the central nervous system. These nerves could therefore influence the brain's systems that give rise to bodily perceptions such as pain.
The sympathetic nerves send information from the central nervous system to the cysts. These nerves normally control functions such as blood vessel constriction and thus could influence the cysts' blood supply and growth.