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Sidorova M, Kronenberg G, Matthes S, Petermann M, Hellweg R, Tuchina O, Bader M, Alenina N, Klempin F. Enduring Effects of Conditional Brain Serotonin Knockdown, Followed by Recovery, on Adult Rat Neurogenesis and Behavior. Cells 2021; 10:3240. [PMID: 34831469 PMCID: PMC8618971 DOI: 10.3390/cells10113240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/14/2021] [Accepted: 11/16/2021] [Indexed: 01/31/2023] Open
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) is a crucial signal in the neurogenic niche of the hippocampus, where it is involved in antidepressant action. Here, we utilized a new transgenic rat model (TetO-shTPH2), where brain 5-HT levels can be acutely altered based on doxycycline (Dox)-inducible shRNA-expression. On/off stimulations of 5-HT concentrations might uniquely mirror the clinical course of major depression (e.g., relapse after discontinuation of antidepressants) in humans. Specifically, we measured 5-HT levels, and 5-HT metabolite 5-HIAA, in various brain areas following acute tryptophan hydroxylase 2 (Tph2) knockdown, and replenishment, and examined behavior and proliferation and survival of newly generated cells in the dentate gyrus. We found that decreased 5-HT levels in the prefrontal cortex and raphe nuclei, but not in the hippocampus of TetO-shTPH2 rats, lead to an enduring anxious phenotype. Surprisingly, the reduction in 5-HT synthesis is associated with increased numbers of BrdU-labeled cells in the dentate gyrus. At 3 weeks of Tph2 replenishment, 5-HT levels return to baseline and survival of newly generated cells is unaffected. We speculate that the acutely induced decrease in 5-HT concentrations and increased neurogenesis might represent a compensatory mechanism.
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Affiliation(s)
- Maria Sidorova
- School of Life Sciences, Immanuel Kant Baltic Federal University, 236041 Kaliningrad, Russia; (M.S.); (O.T.)
- Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany; (S.M.); (M.P.); (M.B.); (N.A.)
| | - Golo Kronenberg
- Department of Psychiatry, Psychotherapy, and Psychosomatics, Psychiatrische Universitätsklinik, 8032 Zürich, Switzerland;
- Department of Psychiatry and Psychotherapy, Charité University Medicine, 10117 Berlin, Germany;
| | - Susann Matthes
- Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany; (S.M.); (M.P.); (M.B.); (N.A.)
| | - Markus Petermann
- Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany; (S.M.); (M.P.); (M.B.); (N.A.)
- Department of Clinical Pharmacy and Pharmacotherapy, Institute of Pharmacy, Martin Luther University, 06120 Halle, Germany
| | - Rainer Hellweg
- Department of Psychiatry and Psychotherapy, Charité University Medicine, 10117 Berlin, Germany;
| | - Oksana Tuchina
- School of Life Sciences, Immanuel Kant Baltic Federal University, 236041 Kaliningrad, Russia; (M.S.); (O.T.)
| | - Michael Bader
- Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany; (S.M.); (M.P.); (M.B.); (N.A.)
| | - Natalia Alenina
- Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany; (S.M.); (M.P.); (M.B.); (N.A.)
- Institute of Translational Biomedicine, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Friederike Klempin
- School of Life Sciences, Immanuel Kant Baltic Federal University, 236041 Kaliningrad, Russia; (M.S.); (O.T.)
- Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany; (S.M.); (M.P.); (M.B.); (N.A.)
- Department of Psychiatry and Psychotherapy, Charité University Medicine, 10117 Berlin, Germany;
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Turkin A, Tuchina O, Klempin F. Microglia Function on Precursor Cells in the Adult Hippocampus and Their Responsiveness to Serotonin Signaling. Front Cell Dev Biol 2021; 9:665739. [PMID: 34109176 PMCID: PMC8182052 DOI: 10.3389/fcell.2021.665739] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/12/2021] [Indexed: 12/18/2022] Open
Abstract
Microglia are the resident immune cells of the adult brain that become activated in response to pathogen- or damage-associated stimuli. The acute inflammatory response to injury, stress, or infection comprises the release of cytokines and phagocytosis of damaged cells. Accumulating evidence indicates chronic microglia-mediated inflammation in diseases of the central nervous system, most notably neurodegenerative disorders, that is associated with disease progression. To understand microglia function in pathology, knowledge of microglia communication with their surroundings during normal state and the release of neurotrophins and growth factors in order to maintain homeostasis of neural circuits is of importance. Recent evidence shows that microglia interact with serotonin, the neurotransmitter crucially involved in adult neurogenesis, and known for its role in antidepressant action. In this chapter, we illustrate how microglia contribute to neuroplasticity of the hippocampus and interact with local factors, e.g., BDNF, and external stimuli that promote neurogenesis. We summarize the recent findings on the role of various receptors in microglia-mediated neurotransmission and particularly focus on microglia’s response to serotonin signaling. We review microglia function in neuroinflammation and neurodegeneration and discuss their novel role in antidepressant mechanisms. This synopsis sheds light on microglia in healthy brain and pathology that involves serotonin and may be a potential therapeutic model by which microglia play a crucial role in the maintenance of mood.
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Affiliation(s)
- Andrei Turkin
- School of Life Sciences, Immanuel Kant Baltic Federal University, Kaliningrad, Russia
| | - Oksana Tuchina
- School of Life Sciences, Immanuel Kant Baltic Federal University, Kaliningrad, Russia
| | - Friederike Klempin
- Department of Psychiatry and Psychotherapy, Charité University Medicine Berlin, Berlin, Germany
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