Melatonin, a widely used naturally occurring hormone used to treat insomnia and jet lag, reverses the formation of a protein complex that is a hallmark of Alzheimer's disease, report researchers in the December 11, 2001 issue of the journal, Biochemistry, published by the American Chemical Society.
The findings of the study conducted by Dr. Miguel Pappolla of the USA Medical Center and the University of South Alabama, and associates from New York University, Case Western Reserve University and the Indiana University School of Medicine, are based upon animal and human cell culture studies.
"Our results clearly demonstrate the ability of melatonin to inhibit the process of forming the "signature" amyloid protein bundles seen in Alzheimer's disease [AD]," said Pappolla. In AD, toxic fibrillar aggregates of a protein called amyloid beta protein are the pathologic landmark of the disease. "What is equally intriguing is that persons with AD also show remarkably lower concentrations of melatonin in their brains," he added.
In the current study melatonin was added to solutions containing the building blocks of the abnormal brain amyloid fibrils along with an additional protein associated with AD, human apoE. Melatonin inhibited the formation of amyloid beta, which is toxic to nerve cells, in the experiments performed.
Because melatonin has antioxidant actions its inhibitory effects were compared to other antioxidants like vitamins C and E, and a synthetic antioxidant. All were without effect. Additionally, a naturally occurring brain chemical very similar to melatonin was evaluated and it, too, lacked inhibitory activity.
"This activity attributed to the 'indole' structure of melatonin appears to be specific'" added Dr. Pappolla. "We also observed melatonin completely preventing neurotoxicity to human nerve cells exposed to amyloid Beta.
"These exciting findings, however, mandate much more research before we can convincingly state melatonin can halt or prevent Alzheimer's disease," he concluded.
"The use of dietary supplements to promote brain function is an exciting aspect of the growing field of nutritional neuroscience", noted Dr. Jeffrey Blumberg, Professor of Nutrition at Tufts University and Scientific Advisory Board member to the Dietary Supplement Education Alliance™, "and these findings from basic research suggest practical applications may not be too far away."
The study was supported by a grant from the National Institute on Aging .