AppNL-G-F/NL-G-F mice overall do not show impaired motivation, but cored amyloid plaques in the striatum are inversely correlated with motivation

Takuya Hamaguchi, Iku Tsutsui-Kimura, Masaru Mimura, Takashi Saito, Takaomi C. Saido, Kenji F. Tanaka

Research output: Contribution to journalArticle

Abstract

Apathy is clinically defined as lack of motivation. Apathy is a frequent symptom in patients with Alzheimer's disease (AD). It is unclear whether amyloid β (Aβ)pathology is associated with apathy. To address this question, we employed the AppNL-G-F/NL-G-F mouse, an Aβ deposition-bearing mouse without neurofibrillary tangles and neuronal cell death throughout the lifespan and used a progressive-ratio (PR)task to monitor instrumental motivation between the ages of 16 and 39 weeks. In the PR task, the number of lever presses to receive one reward increases and the number of active lever presses in the final trial a mouse completes represents a break point, which is an index of motivation. During the observation period, AppNL-G-F/NL-G-F mice overall did not show impaired motivation. However, AppNL-G-F/NL-G-F mice showed a dispersion of the break point at 39 weeks of age within the group. Therefore, we examined the association between the degree of the break point and Aβ pathology; the number of cored amyloid plaques in the striatum was inversely correlated with the degree of motivation. Furthermore, we measured the dopamine transporter (DAT)levels in the subcortical tissues including the striatum using western blot analysis and showed that AppNL-G-F/NL-G-F mice have lower DAT levels than do C57BL/6J mice. Although we could not directly determine the effect of core amyloid plaques on the DAT, the results of this study suggest a pathway through which cored amyloid plaques damage the DAT and cause impaired motivation. These results will draw attention to cored amyloid plaques and will aid researchers searching for new strategies that are effective for the prevention and treatment of impaired motivation.

Original languageEnglish
Article number104470
JournalNeurochemistry International
Volume129
DOIs
Publication statusPublished - 2019 Oct

Keywords

  • Alzheimer
  • Apathy
  • Break point
  • Dopamine transporter
  • Lever
  • Operant

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Cell Biology

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