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. (October 2019)

• Record Type: Journal Article
• Authors: Hamaguchi, Takuya; Tsutsui-Kimura, Iku; Mimura, Masaru; Saito, Takashi; Saido, Takaomi C.; Tanaka, Kenji F.
• Is Part Of: Neurochemistry international. Volume 129(2019)
• Publication Date: 2019-10
• Subjects: Alzheimer -- Apathy -- Operant -- Lever -- Break point -- Dopamine transporter; Neurochemistry -- Periodicals; Neurochemistry -- Periodicals; Neurochimie -- Périodiques; Neurochemistry; Periodicals; 612.804205
• DOI: 10.1016/j.neuint.2019.104470
• Languages: English
• ISSNs: 0197-0186

Abstract

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 App NL - 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, App NL - G-F/NL - G-F mice overall did not show impaired motivation. However, App NL - 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 App NL - 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. Highlights: App NL-G-F/NL-G-F mice overall did not show impaired motivation by 39 weeks of age. Existence of amyloid plaques had no influence on motivation. The striatal cored amyloid plaque number was inversely correlated with motivation. App NL-G-F/NL-G-F mice showed dopamine transporter decrease in subcortical tissues.