While it's a long way from being tested in people, Italian medical researchers claim injections of thyroid hormone may be beneficial for those with multiple sclerosis. In a study published last month in the journal Proceedings of the National Academy of Sciences,¹ doctors at the University of Bologna found that treating mice that had a disease with a similar pathology to MS can repair the destruction in the brain and spinal cord that results.

MS is thought to be an autoimmune disease that affects the central nervous system. The destruction in MS involves the stripping away of a fatty tissue called myelin, responsible for protecting nerve fibers and helping them conduct electrical impulses.  In MS, myelin is lost in multiple areas, leaving scar tissue known as sclerosis. When myelin is gone, the ability of nerves to conduct electrical impulses to and from the brain is disrupted, and the symptoms of MS result.²

Benefits of Thyroid Hormone Postulated
Doctors in the new study believe treatment with thyroid hormone could replace myelin after it's destroyed. According to the authors, previous studies had shown that thyroid hormone was necessary for the normal growth and development of precursor (or parent) cells that eventually form oligodendrocytes (oh-lih-goh-DEN-droh-sites), the cells that make myelin. That was the basis for this study.

In one earlier preclinical trial of their own, the Italian investigators showed that thyroid hormone helped restore myelin. But the strain of rat used in the previous investigation only produces limited myelin destruction. In this case, they wanted to learn if thyroid hormone was also effective in a rat strain that produces much more extensive damage to myelin.

Thyroid Hormone Induces Dramatic Changes
In rats induced to contract the MS-like disease known as experimental allergic encephalomyelitis (EAE), the researchers injected doses of thyroid hormone. Beforehand, they noticed progressive myelin loss in the animals. When analyzing the effect of treatment, they found markers indicating the formation of oligodendrocyte parent cells. The researchers also noticed that the treatment "almost completely restores" levels of an antibody that serves as an indicator of healthy oligodendrocytes.

However, the researchers pointed out that the treatment is only effective when given early.

The Molecular Basis
Why does thyroid hormone work so well in this case? "Positive effects on remyelination could be due to direct thyroid hormone control of gene [activity] for several genes involved in myelin formation in oligodendrocytes," the researchers speculate. Thyroid hormone could also spark the production of certain beneficial growth factors in the central nervous system, they write.

In conclusion, they suggested that the renewal of myelin in MS and experimental diseases like EAE "requires a complex interplay among different cellular partners", and "the role of these partners in this representation changes according to the phase of the disease." As a result, they theorize that multiple therapies will likely be the final goal for an effective MS treatment.

"We suggest that thyroid hormone could have a role in potentiating reluctant myelination by inducing [the precursors of oligodendrocytes] to differentiate into myelinating oligodendrocytes during a specific phase of the disease," the researchers stated.

1. Fernandez M, Giuliani A, Pirondi S et al. Thyroid hormone administration enhances remyelination in chronic demyelinating inflammatory disease. Proc Natl Acad Sci USA 2004 Nov 16;101(46):16363-8. Epub 2004 Nov 16.
2. National Multiple Sclerosis Society. About MS: Symptoms.

John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include coverage of health news for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.