Canadian scientists believe they may be some way to solving the mystery of why women suffering from multiple sclerosis (MS) go into remission while they are pregnant.
According to University of Calgary researchers the hormone prolactin, which is produced in abundance during pregnancy, is responsible for rebuilding the protective coating around nerve cells.
A woman's body produces prolactin in the greatest quantities during pregnancy in order to prepare the body for breast-feeding and the researchers believe this could be the key to treating the devastating neurodegenerative disease.
Multiple sclerosis is caused by the body's immune system turning on itself and attacking myelin, the protective fatty sheath that surrounds the nerve fibres in the brain and spinal cord.
This leads to a progressive loss of sensation and movement.
MS affects approximately 2.5 million people worldwide and Canadians have one of the highest rates of the disease in the world.
The Canadian team have found that prolactin can repair the damaged nerve cells responsible for the disease's devastating symptoms.
They hope the discovery will provide new ways to reverse some of the effects of the disease and improve the quality of life for those who live under its influence.
For their study the Canadian scientists compared pregnant and virgin female mice of the same age and found that pregnant mice had twice as many myelin-producing cells, called oligodendrocytes, and continued to generate new ones during pregnancy.
Dr. Samuel Weiss and Dr.V. Wee Yong of the Hotchkiss Brain Institute, the study authors say the study is the first to show that prolactin is directly responsible for the formation of new myelin in the brains and spinal cords of pregnant mice.
They found that when non-pregnant mice with MS-like lesions were injected with prolactin, their myelin was also repaired.
This they say is the first example of a natural, biological mechanism that produces new myelin in the adult brain and spinal cord and identifies prolactin as a potential therapeutic substance for future testing in people with MS.
Trials on both men and women could start in the next few years after more animal tests are carried out.
The study was funded by the Canadian Institutes of Health Research and the Multiple Sclerosis Society of Canada, with the support of the Alberta Heritage Foundation for Medical Research and the Stem Cell Network
The study is published in the current issue of The Journal of Neuroscience.