The second of two studies on latrepirdine demonstrates new potential for the compound in the treatment of Alzheimer's disease, Parkinson's disease and other neurodegenerative conditions.
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Before the failed trials however, Mount Sinai researchers led by Sam Gandy, MD, PhD, Professor of Neurology, and Psychiatry, and Director of the Mount Sinai Center for Cognitive Health, began studying how latrepirdine worked.
"Despite the failure to replicate the positive Russian trial results in U.S. patients, we found unexpected evidence that latrepirdine had potential as a treatment for a number of neurodegenerative disorders," said Dr. Gandy. "Our study shows that the compound prevents neurodegeneration in multiple ways and should remain a contender for battling these devastating diseases. The anti-amyloid approach – most recently exemplified by reports that a second bapineuzumab trial has failed – might only help patients if begun before the brain pathology begins to build up."
In the new study, the researchers administered the drug to three different systems: yeast, mice and mammal cells all showing build-up of alpha-synuclein, a protein known to cause neurodegeneration. In all three systems, they determined that latrepiridine activated autophagy, the so-called "self-eating" process of cells that protects the brain from neurodegeneration, which targeted synuclein and protected against its toxicity. In mice, the drug reduced the amount of synuclein accumulated in the brain through autophagy.
John Steele, PhD, a Mount Sinai neuroscience graduate student, devoted his PhD thesis to these studies. Lenard Lachenmayer, MD, a postdoctoral fellow working under the supervision of Zhenyu Yue, PhD, Associate Professor of Neurology at Mount Sinai, shares first authorship of the new paper with Steele and with Shulin Ju, PhD, a postdoctoral fellow at Brandeis University working under the direction of Greg Petsko, PhD, and Dagmar Ringe, PhD, both professors of biochemistry, chemistry and neuroscience at Brandeis.
This study is the second of two published by Dr. Gandy's team in Molecular Psychiatry. The first, published July 31, 2012, determined that latrepiridine stopped the toxicity of amyloid-beta protein accumulation in mice present with Alzheimer's disease by inducing autophagy. In that study, they randomly administered either latrepirdine or placebo to mice engineered to have the early stages of Alzheimer's disease and found that, through autophagy, the drug improved memory.
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"The specificity of latrepirdine protection of yeast cells from alpha-synuclein poisoning was unexpected but highly specific and, we believe, occurs at doses of drug potentially relevant to the clinic," Dr. Petsko said.
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Drs. Gandy and Yue are testing whether latrepirdine might be beneficial in treating or preventing disorders associated with high levels of alpha-synuclein such as Parkinson's disease, Lewy body dementia, and REM sleep disorder.
Source-Eurekalert