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Tan Z, Garduño BM, Aburto PF, Chen L, Ha N, Cogram P, Holmes TC, Xu X. Cognitively impaired aged Octodon degus recapitulate major neuropathological features of sporadic Alzheimer's disease. Acta Neuropathol Commun 2022; 10:182. [PMID: 36529803 PMCID: PMC9761982 DOI: 10.1186/s40478-022-01481-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 11/20/2022] [Indexed: 12/23/2022] Open
Abstract
The long-lived Chilean rodent (Octodon degus) has been reported to show spontaneous age-dependent neuropathology and cognitive impairments similar to those observed in human AD. However, the handful of published papers on degus of differing genetic backgrounds yield inconsistent findings about sporadic AD-like pathological features, with notably differing results between lab in-bred degus versus outbred degus. This motivates more extensive characterization of spontaneously occurring AD-like pathology and behavior in degus. In the present study, we show AD-like neuropathological markers in the form of amyloid deposits and tau abnormalities in a cognitively impaired subset of aged outbred degus. Compared to the aged degus that show normal burrowing behavior, the age-matched degus with burrowing behavior deficits correlatively exhibit detectable human AD-like Aβ deposits and tau neuropathology, along with neuroinflammatory markers that include enhanced microglial activation and higher numbers of reactive astrocytes in the brain. This subset of cognitively impaired aged degus also exhibits cerebral amyloid angiopathy and tauopathy. We find robust neurodegenerative features in behaviorally deficient aged degus, including hippocampal neuronal loss, altered parvalbumin and perineuronal net staining in the cortex, and increased c-Fos neuronal activation in the cortex that is consistent with the neural circuit hyperactivity reported in human AD patients. By focusing on the subset of aged degus that show AD-like behavioral deficits and correlative neuropathology, our findings establish outbred degus as a natural model of sporadic AD and demonstrate the potential importance of wild-type outbred genetic backgrounds for AD pathogenesis.
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Affiliation(s)
- Zhiqun Tan
- Department Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA, 92697, USA
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
- The Center for Neural Circuit Mapping, University of California, Irvine, CA, 92697, USA
| | - B Maximiliano Garduño
- Department Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA, 92697, USA
| | - Pedro Fernández Aburto
- Institute of Ecology and Biodiversity, Department of Ecological Sciences, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Lujia Chen
- Department Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA, 92697, USA
| | - Nicole Ha
- Department Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA, 92697, USA
| | - Patricia Cogram
- Institute of Ecology and Biodiversity, Department of Ecological Sciences, Faculty of Sciences, University of Chile, Santiago, Chile
- The Center for Neural Circuit Mapping, University of California, Irvine, CA, 92697, USA
| | - Todd C Holmes
- Department Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, 92697, USA
- The Center for Neural Circuit Mapping, University of California, Irvine, CA, 92697, USA
| | - Xiangmin Xu
- Department Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA, 92697, USA.
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA.
- The Center for Neural Circuit Mapping, University of California, Irvine, CA, 92697, USA.
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