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Surala M, Soso-Zdravkovic L, Munro D, Rifat A, Ouk K, Vida I, Priller J, Madry C. Lifelong absence of microglia alters hippocampal glutamatergic networks but not synapse and spine density. EMBO Rep 2024:10.1038/s44319-024-00130-9. [PMID: 38589666 DOI: 10.1038/s44319-024-00130-9] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 03/13/2024] [Accepted: 03/20/2024] [Indexed: 04/10/2024] Open
Abstract
Microglia sculpt developing neural circuits by eliminating excess synapses in a process called synaptic pruning, by removing apoptotic neurons, and by promoting neuronal survival. To elucidate the role of microglia during embryonic and postnatal brain development, we used a mouse model deficient in microglia throughout life by deletion of the fms-intronic regulatory element (FIRE) in the Csf1r locus. Surprisingly, young adult Csf1rΔFIRE/ΔFIRE mice display no changes in excitatory and inhibitory synapse number and spine density of CA1 hippocampal neurons compared with Csf1r+/+ littermates. However, CA1 neurons are less excitable, receive less CA3 excitatory input and show altered synaptic properties, but this does not affect novel object recognition. Cytokine profiling indicates an anti-inflammatory state along with increases in ApoE levels and reactive astrocytes containing synaptic markers in Csf1rΔFIRE/ΔFIRE mice. Notably, these changes in Csf1rΔFIRE/ΔFIRE mice closely resemble the effects of acute microglial depletion in adult mice after normal development. Our findings suggest that microglia are not mandatory for synaptic pruning, and that in their absence pruning can be achieved by other mechanisms.
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Affiliation(s)
- Michael Surala
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin, Institute of Neurophysiology, Charitéplatz 1, 10117, Berlin, Germany
| | - Luna Soso-Zdravkovic
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin, Institute of Neurophysiology, Charitéplatz 1, 10117, Berlin, Germany
| | - David Munro
- University of Edinburgh and UK Dementia Research Institute, Edinburgh, EH16 4TJ, UK
| | - Ali Rifat
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin, Institute of Neurophysiology, Charitéplatz 1, 10117, Berlin, Germany
- Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Koliane Ouk
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin, Neuropsychiatry and Laboratory of Molecular Psychiatry, Charitéplatz 1, 10117, Berlin, Germany
| | - Imre Vida
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt Universität zu Berlin, Institute for Integrative Neuroanatomy, Charitéplatz 1, 10117, Berlin, Germany
| | - Josef Priller
- University of Edinburgh and UK Dementia Research Institute, Edinburgh, EH16 4TJ, UK.
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin, Neuropsychiatry and Laboratory of Molecular Psychiatry, Charitéplatz 1, 10117, Berlin, Germany.
- DZNE Berlin, 10117, Berlin, Germany.
- Department of Psychiatry and Psychotherapy; School of Medicine and Health, Technical University of Munich and German Center for Mental Health (DZPG), 81675, Munich, Germany.
| | - Christian Madry
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin, Institute of Neurophysiology, Charitéplatz 1, 10117, Berlin, Germany.
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Kaur R, Surala M, Hoger S, Grössmann N, Grimm A, Timaeus L, Kallina W, Hummel T. Pioneer interneurons instruct bilaterality in the Drosophila olfactory sensory map. Sci Adv 2019; 5:eaaw5537. [PMID: 31681838 PMCID: PMC6810332 DOI: 10.1126/sciadv.aaw5537] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 09/28/2019] [Indexed: 06/10/2023]
Abstract
Interhemispheric synaptic connections, a prominent feature in animal nervous systems for the rapid exchange and integration of neuronal information, can appear quite suddenly during brain evolution, raising the question about the underlying developmental mechanism. Here, we show in the Drosophila olfactory system that the induction of a bilateral sensory map, an evolutionary novelty in dipteran flies, is mediated by a unique type of commissural pioneer interneurons (cPINs) via the localized activity of the cell adhesion molecule Neuroglian. Differential Neuroglian signaling in cPINs not only prepatterns the olfactory contralateral tracts but also prevents the targeting of ingrowing sensory axons to their ipsilateral synaptic partners. These results identified a sensitive cellular interaction to switch the sequential assembly of diverse neuron types from a unilateral to a bilateral brain circuit organization.
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Affiliation(s)
- Rashmit Kaur
- Department of Neurobiology, University of Vienna, Althanstrasse 14A, 1090 Vienna, Austria
| | - Michael Surala
- Department of Neurobiology, University of Vienna, Althanstrasse 14A, 1090 Vienna, Austria
| | - Sebastian Hoger
- Department of Neurobiology, University of Vienna, Althanstrasse 14A, 1090 Vienna, Austria
| | - Nicole Grössmann
- Ludwig Boltzmann Institute, Health Technology Assessment (LBI-HTA), Garnisongasse7/20, 1090 Vienna, Austria
- Department of Health Economics, Center for Public Health, Medical University of Vienna, Vienna, Austria
| | - Alexandra Grimm
- Department of Neurobiology, University of Vienna, Althanstrasse 14A, 1090 Vienna, Austria
| | - Lorin Timaeus
- Department of Neurobiology, University of Vienna, Althanstrasse 14A, 1090 Vienna, Austria
| | - Wolfgang Kallina
- Department of Neurobiology, University of Vienna, Althanstrasse 14A, 1090 Vienna, Austria
| | - Thomas Hummel
- Department of Neurobiology, University of Vienna, Althanstrasse 14A, 1090 Vienna, Austria
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