Pregnancy hormone may offer hope for MS patients

By Will Dunham

WASHINGTON (Reuters) - Scientists intrigued by the fact that multiple sclerosis can go into remission when women are pregnant, believe that a pregnancy-related hormone may offer hope for treating the neurological disease.

Researchers at the University of Calgary said a study involving mice showed that a hormone called prolactin triggers production of myelin, a fatty substance that insulates nerve cells in the brain and spinal cord.

In multiple sclerosis, the immune system, which normally protects the body, is believed to attack the myelin that coats nerve cells, causing a worsening loss of sensation and movement that can range from relatively minor to profoundly disabling.

The damage can hamper nerve signals that govern muscle coordination, strength, sensation and vision. There is no cure.

The study, published in the Journal of Neuroscience, indicated that prolactin could be used in people to repair damage caused by MS and improve their symptoms.

Pregnant mice had many more myelin-producing cells, known as oligodendrocytes, than virgin female mice of the same age, the study found.

The researchers destroyed myelin around the nerve cells in the mice, as occurs in MS. Two weeks later, the pregnant mice had twice as much new myelin as the other mice. When the scientists injected prolactin into the non-pregnant mice, their myelin similarly was repaired.

"The implications are that prolactin may be a molecule that can be tested in MS patients for stimulating repair," Samuel Weiss, director of the Hotchkiss Brain Institute at the University of Calgary and senior author of the study, said in an interview.

Prolactin increases in the body during pregnancy and is involved in stimulating milk production among other things.

Weiss said he anticipated that one to two years of additional animal studies will be needed before testing prolactin in people with MS.

'A WHOLE NEW AVENUE'

William McIlroy, medical adviser for the Multiple Sclerosis Society of Canada, which helped fund the study, said scientists have known for years that during pregnancy women with MS experienced an improvement in symptoms, and that this extended into the first couple of months after giving birth.

"Then they sort of go back to the previous level of disease activity again," McIlroy said in an interview.

He said the study links that phenomenon to prolactin and offers hope for treating MS.

"It's repair rather than dampening down the immune system to prevent the damage in the first place. It just opens up a whole new avenue for future treatments down the road," McIlroy said.

He added that the findings also could have implications for other neurological conditions like spinal cord injury.

MS disrupts communication between the brain and other parts of the body.

Most people who develop MS experience their first symptoms between ages 20 and 50. MS affects about twice as many women as men. Its cause is unclear, with environmental and genetic factors possibly contributing.

Initial symptoms can be vision problems. Many patients have muscle weakness in their extremities and difficulty with coordination and balance that may impede walking or standing. MS can cause partial or total paralysis. MS patients can experience pain, numbness and tingling sensations along with slurred speech, tremors, dizziness and fatigue.