In a study conducted using animal mice models, Mayo Clinic researchers have discovered that a modified antioxidant enzyme significantly delayed the onset and increased the survival of mice affected with familial amyotrophic lateral sclerosis (ALS or Lou Gehrig’s disease).
The results of the study are published in the December issue of Annals of Neurology, the journal of the American Neurological Association.
ALS, or Lou Gehrig’s disease, is an uncommon, severely debilitating neurologic disorder that affects some 30,000 people in the United States at any given time. Its cause remains unknown, although in some instances of inherited ALS, a defective gene can be identified.
"This study shows for the first time that the antioxidant enzyme called catalase, when modified by the naturally-occurring polyamine, putrescine, can better penetrate the blood-brain barrier and delay the progression of this disease," says Joseph Poduslo, Ph.D., a Mayo Clinic molecular neurobiologist and the senior author of the study.
"The blood-brain barrier protects the brain from certain toxic substances and allows only a very few select substances to reach portions of the brain. Once the putrescine-modified catalase was able to reach the brain and spinal cord, it delayed the clinical course of the disease," says Dr. Poduslo. "It is hypothesized that this polyamine-modified catalase decreased the levels of hydrogen peroxide and nitric oxide, which are thought to be elevated in ALS. These findings support a direct detrimental role for free radicals in ALS.
"This is the largest increase in survival for any systemically administered drug thus far achieved in mice which have ALS that closely mimics the disease in humans," says Dr. Poduslo. "While other studies remain to be done before human clinical trials can begin, we are very encouraged by these results."
"These results represent an important extension in our understanding of this disease, and how best to proceed with research into treatments," says Eric Sorenson, M.D., a Mayo Clinic neurologist who treats patients with ALS. "While it will be some time before we are ready to begin human clinical trials, this study gives us solid information based on research in mice. Because of this, we will be able to pursue this line of research based on fact and with a much more targeted approach."
ALS causes a progressive degeneration of nerve cells in the central nervous system (brain and spinal cord). The onset is gradual and commonly localized to one part of the body initially. As the disease progresses, its effects are more widespread and may include involuntary twitching of the involved muscles. In its later stages, ALS may involve the muscles of the throat and tongue, making swallowing difficult.
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