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The within-subject application of diffusion tensor MRI and CLARITY reveals brain structural changes in Nrxn2 deletion mice

BACKGROUND: Of the many genetic mutations known to increase the risk of autism spectrum disorder, a large proportion cluster upon synaptic proteins. One such family of presynaptic proteins are the neurexins (NRXN), and recent genetic and mouse evidence has suggested a causative role for NRXN2 in gen...

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Autores principales: Pervolaraki, Eleftheria, Tyson, Adam L., Pibiri, Francesca, Poulter, Steven L., Reichelt, Amy C., Rodgers, R. John, Clapcote, Steven J., Lever, Colin, Andreae, Laura C., Dachtler, James
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6394023/
https://www.ncbi.nlm.nih.gov/pubmed/30858964
http://dx.doi.org/10.1186/s13229-019-0261-9
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author Pervolaraki, Eleftheria
Tyson, Adam L.
Pibiri, Francesca
Poulter, Steven L.
Reichelt, Amy C.
Rodgers, R. John
Clapcote, Steven J.
Lever, Colin
Andreae, Laura C.
Dachtler, James
author_facet Pervolaraki, Eleftheria
Tyson, Adam L.
Pibiri, Francesca
Poulter, Steven L.
Reichelt, Amy C.
Rodgers, R. John
Clapcote, Steven J.
Lever, Colin
Andreae, Laura C.
Dachtler, James
author_sort Pervolaraki, Eleftheria
collection PubMed
description BACKGROUND: Of the many genetic mutations known to increase the risk of autism spectrum disorder, a large proportion cluster upon synaptic proteins. One such family of presynaptic proteins are the neurexins (NRXN), and recent genetic and mouse evidence has suggested a causative role for NRXN2 in generating altered social behaviours. Autism has been conceptualised as a disorder of atypical connectivity, yet how single-gene mutations affect such connectivity remains under-explored. To attempt to address this, we have developed a quantitative analysis of microstructure and structural connectivity leveraging diffusion tensor MRI (DTI) with high-resolution 3D imaging in optically cleared (CLARITY) brain tissue in the same mouse, applied here to the Nrxn2α knockout (KO) model. METHODS: Fixed brains of Nrxn2α KO mice underwent DTI using 9.4 T MRI, and diffusion properties of socially relevant brain regions were quantified. The same tissue was then subjected to CLARITY to immunolabel axons and cell bodies, which were also quantified. RESULTS: DTI revealed increases in fractional anisotropy in the amygdala (including the basolateral nuclei), the anterior cingulate cortex, the orbitofrontal cortex and the hippocampus. Axial diffusivity of the anterior cingulate cortex and orbitofrontal cortex was significantly increased in Nrxn2α KO mice, as were tracts between the amygdala and the orbitofrontal cortex. Using CLARITY, we find significantly altered axonal orientation in the amygdala, orbitofrontal cortex and the anterior cingulate cortex, which was unrelated to cell density. CONCLUSIONS: Our findings demonstrate that deleting a single neurexin gene (Nrxn2α) induces atypical structural connectivity within socially relevant brain regions. More generally, our combined within-subject DTI and CLARITY approach presents a new, more sensitive method of revealing hitherto undetectable differences in the autistic brain. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13229-019-0261-9) contains supplementary material, which is available to authorized users.
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spelling pubmed-63940232019-03-11 The within-subject application of diffusion tensor MRI and CLARITY reveals brain structural changes in Nrxn2 deletion mice Pervolaraki, Eleftheria Tyson, Adam L. Pibiri, Francesca Poulter, Steven L. Reichelt, Amy C. Rodgers, R. John Clapcote, Steven J. Lever, Colin Andreae, Laura C. Dachtler, James Mol Autism Research BACKGROUND: Of the many genetic mutations known to increase the risk of autism spectrum disorder, a large proportion cluster upon synaptic proteins. One such family of presynaptic proteins are the neurexins (NRXN), and recent genetic and mouse evidence has suggested a causative role for NRXN2 in generating altered social behaviours. Autism has been conceptualised as a disorder of atypical connectivity, yet how single-gene mutations affect such connectivity remains under-explored. To attempt to address this, we have developed a quantitative analysis of microstructure and structural connectivity leveraging diffusion tensor MRI (DTI) with high-resolution 3D imaging in optically cleared (CLARITY) brain tissue in the same mouse, applied here to the Nrxn2α knockout (KO) model. METHODS: Fixed brains of Nrxn2α KO mice underwent DTI using 9.4 T MRI, and diffusion properties of socially relevant brain regions were quantified. The same tissue was then subjected to CLARITY to immunolabel axons and cell bodies, which were also quantified. RESULTS: DTI revealed increases in fractional anisotropy in the amygdala (including the basolateral nuclei), the anterior cingulate cortex, the orbitofrontal cortex and the hippocampus. Axial diffusivity of the anterior cingulate cortex and orbitofrontal cortex was significantly increased in Nrxn2α KO mice, as were tracts between the amygdala and the orbitofrontal cortex. Using CLARITY, we find significantly altered axonal orientation in the amygdala, orbitofrontal cortex and the anterior cingulate cortex, which was unrelated to cell density. CONCLUSIONS: Our findings demonstrate that deleting a single neurexin gene (Nrxn2α) induces atypical structural connectivity within socially relevant brain regions. More generally, our combined within-subject DTI and CLARITY approach presents a new, more sensitive method of revealing hitherto undetectable differences in the autistic brain. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13229-019-0261-9) contains supplementary material, which is available to authorized users. BioMed Central 2019-02-28 /pmc/articles/PMC6394023/ /pubmed/30858964 http://dx.doi.org/10.1186/s13229-019-0261-9 Text en © The Author(s). 2019 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Pervolaraki, Eleftheria
Tyson, Adam L.
Pibiri, Francesca
Poulter, Steven L.
Reichelt, Amy C.
Rodgers, R. John
Clapcote, Steven J.
Lever, Colin
Andreae, Laura C.
Dachtler, James
The within-subject application of diffusion tensor MRI and CLARITY reveals brain structural changes in Nrxn2 deletion mice
title The within-subject application of diffusion tensor MRI and CLARITY reveals brain structural changes in Nrxn2 deletion mice
title_full The within-subject application of diffusion tensor MRI and CLARITY reveals brain structural changes in Nrxn2 deletion mice
title_fullStr The within-subject application of diffusion tensor MRI and CLARITY reveals brain structural changes in Nrxn2 deletion mice
title_full_unstemmed The within-subject application of diffusion tensor MRI and CLARITY reveals brain structural changes in Nrxn2 deletion mice
title_short The within-subject application of diffusion tensor MRI and CLARITY reveals brain structural changes in Nrxn2 deletion mice
title_sort within-subject application of diffusion tensor mri and clarity reveals brain structural changes in nrxn2 deletion mice
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6394023/
https://www.ncbi.nlm.nih.gov/pubmed/30858964
http://dx.doi.org/10.1186/s13229-019-0261-9
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