β-amyloid oligomers in aging and Alzheimer's disease

Alzheimer’s disease (AD) is a fatal neurodegenerative disorder, and the most common cause of dementia in the elderly. The cause of AD is not known, but genetic evidence strongly supports the hypothesis that pathological aggregation of the β-amyloid protein (Aβ) triggers the disease process. AD has a long preclinical phase, lasting a decade or more. It is during this preclinical phase, before the irreversible neuron loss that characterizes the dementia phase of the disease, that therapies are most likely to be effective. If we are to block AD during the preclinical phase, we must identify the Aβ species that are present before there are overt symptoms and that are associated with downstream markers of pathology. A specific soluble Aβ assembly, the putative dodecamer Aβ*56, is present in the brains and cerebrospinal fluid of cognitively intact individuals and correlates with markers of synaptic dysfunction and neuronal injury. This assembly also correlates with memory dysfunction in multiple lines of transgenic mice that model the preclinical phase of AD. We suggest that Aβ*56 has a critical role during the earliest phase of AD and might serve as a molecular trigger of the disease

Morris Water Maze Test: Optimization for Mouse Strain and Testing Environment

The Morris water maze (MWM) is a commonly used task to assess hippocampal-dependent spatial learning and memory in transgenic mouse models of disease, including neurocognitive disorders such as Alzheimer’s disease. However, the background strain of the mouse model used can have a substantial effect on the observed behavioral phenotype, with some strains exhibiting superior learning ability relative to others. To ensure differences between transgene negative and transgene positive mice can be detected, identification of a training procedure sensitive to the background strain is essential. Failure to tailor the MWM protocol to the background strain of the mouse model may lead to under- or over- training, thereby masking group differences in probe trials. Here, a MWM protocol tailored for use with the F1 FVB/N x 129S6 background is described. This is a frequently used background strain to study the age-dependent effects of mutant P301L tau (rTg(TauP301L)4510 mice) on the memory deficits associated with Alzheimer’s disease. Also described is a strategy to re-optimize, as dictated by the particular testing environment utilized