Canadian mouse study shows hormone associated with pregnancy may reverse MS

February 23, 2007

Researchers with the University of Calgary in Canada have found that prolactin, a hormone produced during pregnancy, may reverse the progression of multiple sclerosis (MS), according to a paper published this week in The Journal of Neuroscience.

The study, led by Drs. Samuel Weiss and V. Wee Yong of the Hotchkiss Brain Institute, compared virgin and pregnant mice with MS-like lesions introduced by lysolecithin, a chemical which destroys the myelin sheaths around neurons. They found the pregnant mice developed smaller lesions and fewer damaged neurons, and showed signs of repaired neurons. They also found the pregnant mice had higher levels of cells called oligodendrocytes, which create myelin and are able to repair some damaged neurons through remyelination. Because prolactin regulates the levels of precursors of oligodendrocytes, the scientists hypothesized that prolactin levels were responsible for the differences in damage. They also tested virgin mice given additional prolactin, and found results similar to pregnant mice.

Previous studies have shown that other hormones could reduce myelin damage, but this is the first study to show a mechanism to reverse myelin damage, and establish an empirical connection between that mechanism and pregnancy. Dr. Weiss says, “It is thought that during pregnancy, women’s immune systems no longer destroyed the myelin. However, no previous study has tested whether pregnancy actually results in the production of new myelin, which may lead to improvement of symptoms. "We're excited about this result because it suggests to us that prolactin has the potential to be used to enhance the production of new myelin.”

Dr. William McIlroy, national medical advisor for the Multiple Sclerosis Society of Canada, explains the significance of this study: “The results of this study should be well received by people living with MS today. It represents a new insight of how we might be able to reverse some of the effects of the disease and improve the quality of life for those who live under its influence.”

Dr. Luanne Metz, director of the Calgary MS Clinic in the Department of Clinical Neurosciences, University of Calgary and Calgary Health Region, adds, “This discovery has the potential to take MS therapy a step further than current treatments that stabilize the disease in its early stages. By promoting repair, which is the goal of prolactin therapy, we have hope of actually improving symptoms in people with MS.”

Further animal studies need to be done to examine the possibility of side effects, such as lactation in men and non-pregnant women, as well as increased inflammation which could worsen the MS. Researchers believe human trials may begin within a few years.

Funding and support were provided by the Canadian Institutes of Health Research and the Multiple Sclerosis Society of Canada, the Alberta Heritage Foundation for Medical Research and the Stem Cell Network.

MS is an autoimmune disease of the central nervous system where the body attacks the fatty myelin which helps nerves carry electrical signals, causing muscle weakness and spasming which may lead to disability. MS affects approximately one of every 1000 people in North America, northern Europe and Australasia.