growth/size/body
• females sustain normal body weight until 9 months of age, however they show marked reductions in weight at 12 months of age
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behavior/neurological
• preference for cued food in 4 month old mice is intact in the short-term memory test but is affected in the long-term memory component
• at 6 months of age, memory for cued food is altered for both short-term memory and long-term memory, with reduced preference in both delays, indicating an age-dependent reduction in semantic-like retrieval
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• mice show delayed habituation to a novel environment with increasing age
• mice exhibit increased exploration activity during the initial 3 hours of habituation to a novel environment, first seen as a trend at 3 months and with significant differences at 6 and 12 months of age
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• in the open-field water maze, mice show increased path length to find the hidden platform at 6 and 12 months of age, indicating decreased spatial precision
• in the open-field water maze, mutants show about 50% reduction in directed swims and a modest decrease of focal searches, are slower to abstain from wall hugging and maintain scanning, and have a high percentage (about 35%) of chaining responses to solve the task
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• in the spontaneous alternation task of the Y-maze, 6 month old mice show deficient alternations indicating a spatial working memory deficit
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• In the light/dark box, mice remain longer in the light compartment, indicating decreased anxiety
• in the elevated plus maze, mice show a trend in spending more time in the open arms and an increase in exploration (total distance moved)
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• in the open-field water maze, mutants do not show an age-dependent reduction in swim speed as is seen controls, such that at 12 months of age, mutants show enhanced swim speed
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• stride length is reduced in 6 month old females
• however, mice show normal motor coordination and other gait characteristics
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• habituated mice show a decrease in locomotor activity at 6 months of age during both light and dark periods
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nervous system
• toxic APP metabolites are formed that accumulate intra- and extraneuronally in hippocampus and cortex
• accumulation of 56 kDa oligomeric APP (amyloid beta*56) deposits and amyloid beta hexamers in the absence of plaque deposition
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astrocytosis
(
J:215577
)
• astrogliosis in dentate gyrus, hippocampal area CA1, piriform and parietal cortices at 6 and 12 months of age
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• neuronal nuclear inclusions in hippocampal areas, however amyloid plaques are infrequent
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• degenerated neurons are prominent and frequent
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taste/olfaction
N |
• mice show normal olfactory abilities
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