A new mouse model for

A new mouse model for

- Scientists have genetically Alzheimer's a new strain of mice that can be a model of the early stages of Alzheimer's disease. Even before the brains of human patients develop a characteristic of the disease - the clusters of proteins called plaques - their memories are deteriorating and they lose neurons. The new mice, described in tomorrow's issue Nature , also show neurons and memory loss without plaques, suggesting they could provide a testing ground for drugs intended to slow the progression of the disease in humans. But all the experts are not convinced that the team created an accurate model for early Alzheimer's disease.

In recent years, plaques, which accumulate over time from sticky protein, called insoluble amyloid, became the first suspect to cause the debilitating symptoms of Alzheimer's disease . But some researchers have come to suspect that another protein, produced as an intermediate step when cells chop a long molecule called amyloid precursor protein (APP) to form amyloid could injure neurons before scar plates the brain. test tube studies, for example, suggested that the APP fragment is toxic to neurons.

Now Jo Nalbantoglu, a molecular biologist at McGill University in Montreal and colleagues created mice that have brains that are riddled with these precursor fragments. To do this, they added that the part of the APP gene for amyloid precursor mouse embryos. When they grew into adults, the experimental group had much more trouble remembering how to solve a maze that made the mice in a control group.

Researchers then dissected the brains to see why. When they electrically stimulated living slices of the hippocampus, a memory center for the signal persisted in neural pathways known for 0 minutes in the control mice, but died after about 15 minutes in mice with large amounts of amyloid precursor fragment. In addition, 18-month-old experimental mice had a lower density of 20% of the neurons in the CA1 region of the hippocampus - an effect observed in human Alzheimer's patients. Previous mouse models, however, have failed to show that death characteristic of nerve cells.

neuroscientist Mark Mattson of the University of Kentucky, Lexington, called the work "important progress." But Sangram Sisodia Johns Hopkins University School of Medicine, who is working on mouse models of Alzheimer ' Alzheimer others think neuronal loss could be an artifact of how the Canadian team had neurons to be a true Alzheimer model mice are going to produce amyloid plaques and develop -. and they show no biochemical evidence either. then Nalbantoglu plans to seek these plaques in aged mice while investigating how the precursor proteins could be the cause of memory loss.

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