Elsevier

Neurobiology of Aging

Volume 33, Issue 1, January 2012, Pages 196.e29-196.e40
Neurobiology of Aging

Abstract of online article
Motor deficits, neuron loss, and reduced anxiety coinciding with axonal degeneration and intraneuronal Aβ aggregation in the 5XFAD mouse model of Alzheimer's disease

https://doi.org/10.1016/j.neurobiolaging.2010.05.027Get rights and content

Abstract

In the present report, we extend previous findings in the 5XFAD mouse model and demonstrate that these mice develop an age-dependent motor phenotype in addition to working memory deficits and reduced anxiety levels as demonstrated in an elevated plus maze task. Employing a variety of N- and C-terminal specific Aβ antibodies, abundant intraneuronal and plaque-associated pathology, including accumulation of pyroglutamate Aβ, was observed as early as the age of 3 months. Using unbiased stereology, we demonstrate that the 5XFAD mice develop a significant selective neuron loss in layer 5 of the cortex, leaving the overall neuron number of the total frontal cortex and hippocampus unaffected. This observation coincides with the accumulation of intraneuronal Aβ peptides only in cortical Layer 5, but not in CA1, despite comparable APP expression levels. The motor phenotype correlates with abundant spinal cord pathology, as demonstrated by abundant intraneuronal Aβ accumulation and extracellular plaque deposition. In addition, comparable to the APP/PS1KI mouse model, 5XFAD mice develop an age-dependent axonopathy likely contributing to the behavioral deficits.

Introduction

Alzheimer's disease (AD) is a severe neurodegenerative disorder representing the most frequent form of dementia. It is characterized by the deposition of extracellular plaques composed of the mainly 40–42 amino acid Aβ peptide, as well as intracellular neurofibrillary tangles consisting of hyperphosphorylated Tau protein. Over the past years numerous transgenic mouse models of AD have been generated, reflecting underlying pathological alterations (Duyckaerts et al., 2008). Extracellular Aβ deposition, as well as therapeutic strategies for plaque removal, have dominated research efforts in AD during the last years, however, the presence of intraneuronal Aβ accumulations has recently gained in importance. It has been shown that Aβ42 accumulates within neurons in AD-vulnerable brain regions in AD (Gouras et al., 2000) and Down syndrome patients (Gyure et al., 2001) and that neurons from sporadic and familial AD cases contain increased Aβ42 levels and an increased Aβ42/Aβ40 ratio (Aoki et al., 2008).

The data in AD mouse models regarding intraneuronal Aβ are much more consistent and an increasing consensus can be observed during the past years. Early intraneuronal accumulation has been reported in several mouse models, including APPSDLPS1M146L (Wirths et al., 2001), APPSLPS1M146L (Wirths et al., 2002), Tg2576 (Takahashi et al., 2002), 3xTg-AD (Oddo et al., 2003), 5XFAD (Oakley et al., 2006), APPArc (Knobloch et al., 2007, Lord et al., 2006), APPT714I mice (Van Broeck et al., 2008), in APPSLPS1KIM233T, L235P mice (Casas et al., 2004) in which it was recently shown to correlate with neuron loss (Breyhan et al., 2009; Christensen et al., 2008; Christensen et al., 2010), as well as in TBA2 mice expressing pyroglutamate modified Aβ3-42 (Wirths et al., 2009).

5XFAD mice expressing human APP with the Swedish, Florida (I716V) and London mutations, together with mutant PS1 (M14 6L, L28 6V) under the control of the murine Thy-1 promoter (Oakley et al., 2006) are particularly interesting due to cointegration of the transgenes, enabling easy generation of multitransgenic AD mouse models. These mice were generated on a B6/SJL-hybrid background and have been backcrossed with C57Bl6/J mice for five generations to facilitate comparison with other models which are mostly kept on the C57Bl6 genetic background.

In the present report, we extent previous findings in the 5XFAD mouse model and demonstrate that they develop an age-dependent motor phenotype in addition to working memory deficits in an alternation task and reduced anxiety levels as shown in the elevated plus maze task. Quantification of cortical layer 5 neurons in 12 month old 5XFAD mice by means of design-based stereology confirmed the previously assumed loss of neurons in this brain regions (Oakley et al., 2006, Ohno et al., 2007), however, the overall neuron number in frontal cortex and hippocampal CA1 layer was unchanged compared with age-matched wild-type littermates. This observation coincides with the accumulation of intraneuronal Aβ peptides only in cortical Layer 5, but not in CA1. The motor phenotype correlates well with abundant spinal cord pathology, including intraneuronal Aβ accumulation and development of an age-dependent axonal degeneration.

Section snippets

Transgenic mice

The generation of 5XFAD mice (Tg6799) has been described previously (Oakley et al., 2006). In brief, 5XFAD overexpress the 695 amino acids isoform of the human amyloid precursor protein (APP695) carrying the Swedish, Florida, and London mutations under the control of the murine Thy-1-promoter. In addition, human presenilin-1 (PS1) carrying the M14 6L and L28 6V mutations mice is expressed also under the control of the murine Thy-1-promoter. Five male mice on a C57Bl/6 x SJL genetic background

Phenotypical characterization

5XFAD mice showed a reduced body weight in comparison with their WT littermates. Analysis by Two-way ANOVA revealed a significant genotype effect starting at 9 months of age (p < 0.05, Fig. 1A). In addition, 5XFAD mice showed a characteristic clasping phenotype presented by an unusual simultaneous retraction of both fore- and hind paws. Quantitative measurement of this behavior at 12 mo of age, by suspending the animals by their tail and evaluating the clasping score, revealed a significant

Discussion

The 5XFAD mouse model represents a double transgenic APP/PS1 mouse line coexpressing five familial Alzheimer disease (5XFAD) mutations that are inherited together and lead to accelerated plaque formation and increased Aβ42 levels. It was previously described as one of the few AD models showing several AD hallmarks, including neuron loss (Oakley et al., 2006). The aim of the present work was to perform a detailed characterization of the 5XFAD mouse model on a C57/BLJ genetic background,

Disclosure statement

Animal studies were performed with the approval of the Local Research Ethics Committee in accordance with national and international guidelines. All efforts were made to minimize animal suffering and the number of animals used. The authors have no financial, personal, or other conflicts of interest to disclose.

Acknowledgements

The expert technical assistance of Petra Tucholla is gratefully acknowledged. We thank Gerd Multhaup for the generous gift of 23850 and 692 antibodies. This work was supported by The European Commission, Marie Curie Early Stage Training, MEST-CT-2005-020013 (NEURAD), Alzheimer Ph.D. Graduate School, Alzheimer Forschung Initiative e.V. (to O.W.), and the Competence Network Degenerative Dementias of the German Federal Ministry of Education (grant no. 01 GI 0718, to T.A.B.).

References (65)

  • R. Lalonde et al.

    Spatial learning, exploration, anxiety, and motor coordination in female APP23 transgenic mice with the Swedish mutation

    Brain Res

    (2002)
  • R. Lalonde et al.

    Exploratory activity and spatial learning in 12 month old APP(695)SWE/co+PS1/DeltaE9 mice with amyloid plaques

    Neurosci Lett

    (2005)
  • R. Lalonde et al.

    Transgenic mice expressing the betaAPP695SWE mutation: effects on exploratory activity, anxiety, and motor coordination

    Brain Res

    (2003)
  • R. Lalonde et al.

    Transgenic mice expressing the PS1-A246E mutation: effects on spatial learning, exploration, anxiety, and motor coordination

    Behav. Brain Res

    (2003)
  • A. Lord et al.

    The Arctic Alzheimer mutation facilitates early intraneuronal Abeta aggregation and senile plaque formation in transgenic mice

    Neurobiol. Aging

    (2006)
  • S. Oddo et al.

    Triple-transgenic model of Alzheimer's disease with plaques and tangles: intracellular Abeta and synaptic dysfunction

    Neuron

    (2003)
  • M. Ohno

    Failures to reconsolidate memory in a mouse model of Alzheimer's disease

    Neurobiol. Learn. Mem

    (2009)
  • M. Ohno et al.

    BACE1 gene deletion prevents neuron loss and memory deficits in 5XFAD APP/PS1 transgenic mice

    Neurobiol. Dis

    (2007)
  • C. Schmitz et al.

    Design-based stereology in neuroscience

    Neuroscience

    (2005)
  • C. Schmitz et al.

    Hippocampal neuron loss exceeds amyloid plaque load in a transgenic mouse model of Alzheimer's disease

    Am. J. Pathol

    (2004)
  • K. Spittaels et al.

    Prominent axonopathy in the brain and spinal cord of transgenic mice overexpressing four-repeat human tau protein

    Am. J. Pathol

    (1999)
  • R.H. Takahashi et al.

    Intraneuronal Alzheimer abeta42 accumulates in multivesicular bodies and is associated with synaptic pathology

    Am. J. Pathol

    (2002)
  • I. Tesseur et al.

    Prominent axonopathy and disruption of axonal transport in transgenic mice expressing human apolipoprotein E4 in neurons of brain and spinal cord

    Am. J. Pathol

    (2000)
  • B. Van Broeck et al.

    Intraneuronal amyloid beta and reduced brain volume in a novel APP T714I mouse model for Alzheimer's disease

    Neurobiol. Aging

    (2008)
  • M.J. West

    Design-based stereological methods for counting neurons

    Prog. Brain Res

    (2002)
  • O. Wirths et al.

    Deficits in working memory and motor performance in the APP/PS1ki mouse model for Alzheimer's disease

    Neurobiol. Aging

    (2008)
  • O. Wirths et al.

    Intraneuronal Abeta accumulation precedes plaque formation in beta-amyloid precursor protein and presenilin-1 double-transgenic mice

    Neurosci. Lett

    (2001)
  • O. Wirths et al.

    Age-dependent axonal degeneration in an Alzheimer mouse model

    Neurobiol. Aging

    (2007)
  • X. Zhu et al.

    Alzheimer's disease: an intracellular movement disorder?

    Trends Mol. Med

    (2005)
  • M. Aoki et al.

    Amyloid beta-peptide levels in laser capture microdissected cornu ammonis 1 pyramidal neurons of Alzheimer's brain

    Neuroreport

    (2008)
  • G.W. Arendash et al.

    Behavioral assessment of Alzheimer's transgenic mice following long-term Abeta vaccination: task specificity and correlations between Abeta deposition and spatial memory

    DNA Cell Biol

    (2001)
  • H. Breyhan et al.

    APP/PS1KI bigenic mice develop early synaptic deficits and hippocampus atrophy

    Acta Neuropathol

    (2009)
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