growth/size/body
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• mice are smaller than wild-type controls at 12-17 weeks of age
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• body weight is reduced at 12-17 weeks of age
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behavior/neurological
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• mice show no signs of a gait disorder in the rotarod test, balance-beam test and open-field test
• no alterations are noted in grip strength, pain sensitivity, motor coordination or balance, anxiety-related behavior, sociability or social novelty preference, and spatial reference or working memory
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• when traversing the wide beam in the balance-beam test, mice stop and occasionally turn in the opposite direction instead of heading straight for the goal, resulting in an increased number of movements that may reflect a decline in goal-oriented behavior, attention and concentration
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• in the cued fear-conditioning test, mice show reduced freezing time and increased distance traveled relative to wild-type controls, indicating impaired cued fear memory
• however, contextual fear memory is normal
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• in the Porsolt forced-swim test, mice exhibit a longer immobility time and a shorter distance traveled on day 1, but not on day 2, relative to age-matched wild-type controls at both 12-17 weeks and 56-66 weeks of age, suggesting a depression-like behavior
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• mice show a reduced startle response to a single loud sound at 120 dB, but not to a single sound at 110 db, relative to wild-type controls
• however, prepulse inhibition is normal
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• in the home-cage social-interaction test, mice exhibit a higher mean activity level than wild-type controls, indicating hyperactivity in a familiar environment
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nervous system
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• mice show no signs of hereditary spastic paraplegia
• synaptic plasticity in the hippocampus appears unaffected
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