Research Models

TgF344-AD

Species: Rat
Genes: APP, PSEN1
Mutations: APP KM670/671NL (Swedish), PSEN1: deltaE9
Modification: APP: Transgenic; PSEN1: Transgenic
Disease Relevance: Alzheimer's Disease
Strain Name: N/A
Genetic Background: Fischer 344
Availability: Available through Terrence Town.

Summary

TgF344-AD rats express human APP with the Swedish mutation and human PSEN1 with the Δ exon 9 mutation. Both transgenes are driven by the mouse prion promoter (Cohen et al., 2013).

Compared with levels of the endogenous rat proteins, TgF344-AD rats express 2.6 times more human APP and 6.2 times more human PSEN1 in the brain (Cohen et al., 2013). TgF344-AD rats show age-dependent increases in levels of detergent-soluble and detergent-insoluble Aβ40 and Aβ42 between 6 and 26 months; the Aβ42/Aβ40 ratio increases with age in the soluble fraction but decreases in the insoluble fraction (Cohen et al., 2013).

Neuropathology

TgF344-AD rats show an age-dependent accumulation of amyloid plaques in hippocampus and cortex between 6 and 26 months of age. Plaques are also detected in the striatum and cerebellum. Cerebral amyloid angiopathy occurs in cortex, hippocampus, striatum, and cerebellum. Plaque-associated neuritic dystrophies are observed (Cohen et al., 2013).

Tau pathology has also been reported in TgF344-AD rats (Cohen et al., 2013). Antibodies directed against specific phospho-tau epitopes (AT8, CP13, pS199/202, pS396) and conformation-selective tau antibodies (MCI and PHF1) stained neurons in hippocampi and cortices of 16-month animals. Silver staining and immunostaining with antibody CP13 revealed neurofibrillary tangle-like structures.

Microgliosis and astrogliosis are apparent by 6 months (Cohen et al., 2013).

Neuron numbers in hippocampus and cortex of TgF344-AD rats are similar to those of wild-type animals at 6 months of age, but by 16 months there is an approximate 40 percent loss of neurons (Cohen et al., 2013).

Hirano bodies and spongiform vacuolar pathology are seen at 16 months (Cohen et al., 2013).

The locus coeruleus may be one of the first brain regions to exhibit tau pathology during the development of AD (Braak et al., 2011), prompting an investigation of locus coeruleus pathology and noradrenergic markers in TgF344-AD rats (Rorabaugh et al., 2017). Hyperphosphorylated tau was detected in the locus coeruleus by 6 months of age, prior to its appearance in medial entorhinal cortex or hippocampus. No neurofibrillary tangles, amyloid plaques, astrogliosis, or neuron loss were seen in the locus coeruleus in animals up to 16 months of age. However, the norepinephrine content in the hippocampus was lower in TgF344-AD rats than in wild-type rats at 16 months, while no differences between the genotypes were seen in the prefrontal cortex at this time.

Electrophysiology

Network dysfunction, assessed as the coupling between the phase of theta oscillations and the amplitude of gamma oscillations, was recorded in the somatosensory cortices of 9-month transgenic rats (Joo et al., 2017).

Cognition/Behavior

When tested at 6, 15, and 24 months, transgenic rats did not show neurologic abnormalities in a screen that included the righting response, eye blink, ear twitch, limb withdrawal in response to tactile stimuli, orienting response to olfactory and visual stimuli, startle response, and visual and tactile placing (Cohen et al., 2013).

Fifteen-month TgF344-AD rats were hyperactive in the open-field test (Cohen et al., 2013). In the elevated plus-maze, 4- to 6-month TgF344-AD rats spent less time in the open arms than did wild-type rats, perhaps indicating increased anxiety (Pentkowski et al., 2018).

Reversal learning in the Morris water maze was impaired in animals as young as 6 months of age (Rorabaugh et al., 2017), and learning deficits in the Barnes maze were reported in 15-month TgF344-AD rats (Cohen et al., 2013).

Deficits in novel object recognition were observed at 24 months (Cohen et al., 2013).

Imaging

PET imaging showed uptake of the tracer 18F-FDDNP in the frontal cortices of 15-month transgenic rats (Cohen et al., 2013). This tracer binds amyloid plaques and, to a lesser extent, neurofibrillary tangles (Agdeppa et al., 2001).

In a study of male animals, MRI showed differences in structural and functional connectivity between TgF344-AD rats (approximately 6 months of age) and wild-type rats (about 5 months of age) (Munoz-Moreno et al., 2018).

Other

Cerebrovascular dysfunction accompanies vascular amyloid deposition: In cortical penetrating arterioles, normal increases in blood flow in response to hypercapnia were abolished (Joo et al., 2017).

Compared with wild-type rats, TgF344-AD rats showed decreased visual acuity but increased contrast sensitivity at 19 months of age (Tsai et al., 2014).

Modification Details

Pronuclei of Fischer 344 zygotes were co-injected with two cDNAs encoding human APP with the Swedish mutation and PSEN1 with the Δ exon 9 mutation; both genes are driven by the mouse prion promoter (Cohen et al., 2013).

Related Strain

TgF344-AD rats on a Fischer344/NHsd background are available from the Rat Resource & Research Center, Stock# 00699.

Phenotype Characterization

When visualized, these models will distributed over a 18 month timeline demarcated at the following intervals: 1mo, 3mo, 6mo, 9mo, 12mo, 15mo, 18mo+.

Absent

No Data

  • Synaptic Loss
  • Changes in LTP/LTD

Plaques

Age-dependent accumulation of amyloid plaques in hippocampus and cortex between 6 and 26 months of age.

Tangles

Structures similar in appearance to neurofibrillary tangles revealed by Gallyas staining and immunostaining using an antibody directed against phospo-tau.

Neuronal Loss

Approximate 40 percent loss of neurons in hippocampus and cortex by 16 months.

Gliosis

Microgliosis and astrogliosis are apparent by 6 months.

Synaptic Loss

No data.

Changes in LTP/LTD

No data.

Cognitive Impairment

Deficits in reversal learning in the Morris water maze apparent by 6 months.

Last Updated: 31 Aug 2018

COMMENTS / QUESTIONS

  1. This work deserves a lot of attention. One thing that is unclear is the definition of tauopathy.

    View all comments by Takaomi Saido

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References

Paper Citations

  1. . A transgenic Alzheimer rat with plaques, tau pathology, behavioral impairment, oligomeric aβ, and frank neuronal loss. J Neurosci. 2013 Apr 10;33(15):6245-56. PubMed.
  2. . Stages of the pathologic process in Alzheimer disease: age categories from 1 to 100 years. J Neuropathol Exp Neurol. 2011 Nov;70(11):960-9. PubMed.
  3. . Chemogenetic locus coeruleus activation restores reversal learning in a rat model of Alzheimer's disease. Brain. 2017 Nov 1;140(11):3023-3038. PubMed.
  4. . Early neurovascular dysfunction in a transgenic rat model of Alzheimer's disease. Sci Rep. 2017 Apr 12;7:46427. PubMed.
  5. . Anxiety-like behavior as an early endophenotype in the TgF344-AD rat model of Alzheimer's disease. Neurobiol Aging. 2018 Jan;61:169-176. Epub 2017 Oct 5 PubMed.
  6. . Binding characteristics of radiofluorinated 6-dialkylamino-2-naphthylethylidene derivatives as positron emission tomography imaging probes for beta-amyloid plaques in Alzheimer's disease. J Neurosci. 2001 Dec 15;21(24):RC189. PubMed.
  7. . Early brain connectivity alterations and cognitive impairment in a rat model of Alzheimer's disease. Alzheimers Res Ther. 2018 Feb 7;10(1):16. PubMed.
  8. . Ocular changes in TgF344-AD rat model of Alzheimer's disease. Invest Ophthalmol Vis Sci. 2014 Jan 29;55(1):523-34. PubMed.

Other Citations

  1. Terrence Town

External Citations

  1. Rat Resource & Research Center, Stock# 00699

Further Reading