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Bosch PJ, Kerr G, Cole R, Warwick CA, Wendt LH, Pradeep A, Bagnall E, Aldridge GM. Enhanced Spine Stability and Survival Lead to Increases in Dendritic Spine Density as an Early Response to Local Alpha-Synuclein Overexpression in Mouse Prefrontal Cortex. Cell Mol Neurobiol 2024; 44:42. [PMID: 38668880 PMCID: PMC11052719 DOI: 10.1007/s10571-024-01472-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 03/18/2024] [Indexed: 04/29/2024]
Abstract
Lewy Body Dementias (LBD), including Parkinson's disease dementia and Dementia with Lewy Bodies, are characterized by widespread accumulation of intracellular alpha-Synuclein protein deposits in regions beyond the brainstem, including in the cortex. However, the impact of local pathology in the cortex is unknown. To investigate this, we employed viral overexpression of human alpha-Synuclein protein targeting the mouse prefrontal cortex (PFC). We then used in vivo 2-photon microscopy to image awake head-fixed mice via an implanted chronic cranial window to assess the early consequences of alpha-Synuclein overexpression in the weeks following overexpression. We imaged apical tufts of Layer V pyramidal neurons in the PFC of Thy1-YFP transgenic mice at 1-week intervals from 1 to 2 weeks before and 9 weeks following viral overexpression, allowing analysis of dynamic changes in dendritic spines. We found an increase in the relative dendritic spine density following local overexpression of alpha-Synuclein, beginning at 5 weeks post-injection, and persisting for the remainder of the study. We found that alpha-Synuclein overexpression led to an increased percentage and longevity of newly-persistent spines, without significant changes in the total density of newly formed or eliminated spines. A follow-up study utilizing confocal microscopy revealed that the increased spine density is found in cortical cells within the alpha-Synuclein injection site, but negative for alpha-Synuclein phosphorylation at Serine-129, highlighting the potential for effects of dose and local circuits on spine survival. These findings have important implications for the physiological role and early pathological stages of alpha-Synuclein in the cortex.
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Affiliation(s)
- Peter J Bosch
- Department of Neurology, Carver College of Medicine, University of Iowa, 169 Newton Road, Pappajohn Biomedical Discovery Building, Iowa City, 52242, USA
| | - Gemma Kerr
- Department of Neurology, Carver College of Medicine, University of Iowa, 169 Newton Road, Pappajohn Biomedical Discovery Building, Iowa City, 52242, USA
| | - Rachel Cole
- Department of Neurology, Carver College of Medicine, University of Iowa, 169 Newton Road, Pappajohn Biomedical Discovery Building, Iowa City, 52242, USA
| | | | - Linder H Wendt
- Institute for Clinical and Translational Science, University of Iowa, Iowa City, IA, USA
| | - Akash Pradeep
- Department of Neurology, Carver College of Medicine, University of Iowa, 169 Newton Road, Pappajohn Biomedical Discovery Building, Iowa City, 52242, USA
| | - Emma Bagnall
- Department of Neurology, Carver College of Medicine, University of Iowa, 169 Newton Road, Pappajohn Biomedical Discovery Building, Iowa City, 52242, USA
| | - Georgina M Aldridge
- Department of Neurology, Carver College of Medicine, University of Iowa, 169 Newton Road, Pappajohn Biomedical Discovery Building, Iowa City, 52242, USA.
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, USA.
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Bosch PJ, Kerr G, Cole R, Warwick CA, Wendt LH, Pradeep A, Bagnall E, Aldridge GM. Enhanced spine stability and survival lead to increases in dendritic spine density as an early response to local alpha-synuclein overexpression in mouse prefrontal cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.28.559765. [PMID: 37808820 PMCID: PMC10557684 DOI: 10.1101/2023.09.28.559765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Lewy Body Dementias (LBD), including Parkinson's disease dementia and Dementia with Lewy Bodies, are characterized by widespread accumulation of intracellular alpha-Synuclein protein deposits in regions beyond the brainstem, including in the cortex. Patients with LBDs develop cognitive changes, including abnormalities in executive function, attention, hallucinations, slowed processing, and cognitive fluctuations. The causes of these non-motor symptoms remain unclear; however, accumulation of alpha-Synuclein aggregates in the cortex and subsequent interference of synaptic and cellular function could contribute to psychiatric and cognitive symptoms. It is unknown how the cortex responds to local pathology in the absence of significant secondary effects of alpha-Synuclein pathology in the brainstem. To investigate this, we employed viral overexpression of human alpha-Synuclein protein targeting the mouse prefrontal cortex (PFC). We then used in vivo 2-photon microscopy to image awake head-fixed mice via an implanted chronic cranial window to assess the early consequences of alpha-Synuclein overexpression in the weeks following overexpression. We imaged apical tufts of Layer V pyramidal neurons in the PFC of Thy1-YFP transgenic mice at 1-week intervals from 1-2 weeks before and 9 weeks following viral overexpression, allowing analysis of dynamic changes in dendritic spines. We found an increase in the relative dendritic spine density following local overexpression of alpha-Synuclein, beginning at 5 weeks post-injection, and persisting for the remainder of the study. We found that alpha-Synuclein overexpression led to an increased percentage and longevity of newly-persistent spines, without significant changes in the total density of newly formed or eliminated spines. A follow up study utilizing confocal microscopy revealed that the increased spine density is found in cortical cells within the alpha-Synuclein injection site, but negative for alpha-Synuclein phosphorylation at Serine-129, highlighting the potential for effects of dose and local circuits on spine survival. These findings have important implications for the physiological role and early pathological stages of alpha-Synuclein in the cortex.
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Khiroug L, Verkhratsky A. Coming full circle: In vivo Veritas, or expanding the neuroscience frontier. Cell Calcium 2021; 98:102452. [PMID: 34399234 DOI: 10.1016/j.ceca.2021.102452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 08/02/2021] [Indexed: 11/25/2022]
Abstract
The 25-century long history of brain science can be divided into four distinct 'Eras': Era 1 (∼2000 years) started around 500 BC with reductionist studies of human and animal brains using invasive in vivo and ex vivo methods; Era 2 (∼200 years) started in the 17th century and introduced the first invasive methods to study the function of living tissues; Era 3 started around 1838 and is the ongoing era of cellular neurophysiology; finally, Era 4 (in statu nascendi) is the era of non-invasive, holistic yet mechanistic, studies of the brain. Animal experimentation is becoming increasingly more holistic as multimodal imaging and recording techniques are combined in a single experiment on the brain of awake behaving animal. This newly emerged approach can be called in vigilo (from Latin 'in awake' or 'in vigilant state'), by analogy to the earlier introduced terms in vivo or in vitro. We introduce the Special Issue "In Vigilo Veritas: New Frontiers of Optical Imaging and Electrical Recording in the Brain of Awake Behaving Mice", which features original research articles and reviews that represent some of the finest examples of a truly multimodal studies, where behavioural readouts and tasks are combined in the same longitudinal experiment and on the same mouse with the two-photon imaging, optogenetics and/or electrophysiological recordings. This exciting multi-methodological approach creates a fertile ground for breakthrough discoveries in neurophysiology and neuropsychology of an awake behaving mammalian brain.
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Affiliation(s)
- Leonard Khiroug
- Neuroscience Center, University of Helsinki, 00790 Helsinki, Finland.
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK; Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain; Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102, Vilnius, Lithuania
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