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Voelz C, Schaack LEM, Kogel V, Beyer C, Seitz J, Trinh S. Reversibility of Endoplasmic Reticulum Stress Markers During Long-Term Glucose Starvation in Astrocytes. J Mol Neurosci 2024; 74:53. [PMID: 38750341 PMCID: PMC11096255 DOI: 10.1007/s12031-024-02223-5] [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: 12/14/2023] [Accepted: 04/10/2024] [Indexed: 05/18/2024]
Abstract
Previous studies have demonstrated a brain volume decrease linked to long-term starvation in patients with anorexia nervosa (AN). Food intake is critically diminished in this disorder, leading to one of the highest mortality rates within the psychiatric disease spectrum. As reported in animal models, astrocytes seem to be the most affected cell type in AN. In a recently established primary cell culture model, an elevated unfolded protein response (UPR) was observed in long-term glucose semi-starved astrocytes. A well-functioning protein machinery is essential for every cell, and prolonged UPR will lead to cell death. As a nucleic acid stress-sensing pathway with the activator located in the endoplasmic reticulum, the regulation of the cGAS-STING pathway (cyclic GMP-AMP synthase/stimulator of interferon genes) was additionally investigated in the starvation context. In the current study, a glucose semi-starvation protocol of 15 days, during which cells were supplied with 2 mM glucose in the medium, was prolonged with an additional 6-day long recovery period. Our findings showed that increased UPR mRNA expression was reversible after re-establishing the standard glucose concentration of 25 mM. Furthermore, we were able to verify the presence of cGAS and STING in astrocytes with a characteristic presence of cGAS in the astrocyte nucleus during starvation. A correlation between STING and the glial fibrillary acidic protein (GFAP) could be established, hinting at a conditional presence of STING with a specific astrocyte phenotype.
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Affiliation(s)
- Clara Voelz
- Institute of Neuroanatomy, RWTH Aachen University, Aachen, Germany.
| | - Lena E M Schaack
- Institute of Neuroanatomy, RWTH Aachen University, Aachen, Germany
| | - Vanessa Kogel
- Institute of Neuroanatomy, RWTH Aachen University, Aachen, Germany
| | - Cordian Beyer
- Institute of Neuroanatomy, RWTH Aachen University, Aachen, Germany
| | - Jochen Seitz
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University of Duisburg-Essen, Essen, Germany
| | - Stefanie Trinh
- Institute of Neuroanatomy, RWTH Aachen University, Aachen, Germany
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Kipp M. How to Use the Cuprizone Model to Study De- and Remyelination. Int J Mol Sci 2024; 25:1445. [PMID: 38338724 PMCID: PMC10855335 DOI: 10.3390/ijms25031445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 01/19/2024] [Accepted: 01/22/2024] [Indexed: 02/12/2024] Open
Abstract
Multiple sclerosis (MS) is an autoimmune and inflammatory disorder affecting the central nervous system whose cause is still largely unknown. Oligodendrocyte degeneration results in demyelination of axons, which can eventually be repaired by a mechanism called remyelination. Prevention of demyelination and the pharmacological support of remyelination are two promising strategies to ameliorate disease progression in MS patients. The cuprizone model is commonly employed to investigate oligodendrocyte degeneration mechanisms or to explore remyelination pathways. During the last decades, several different protocols have been applied, and all have their pros and cons. This article intends to offer guidance for conducting pre-clinical trials using the cuprizone model in mice, focusing on discovering new treatment approaches to prevent oligodendrocyte degeneration or enhance remyelination.
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Affiliation(s)
- Markus Kipp
- Rostock University Medical Center, Institute of Anatomy, 18057 Rostock, Germany
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Zimmermann A, Böge N, Schuster K, Staffeld A, Lang S, Gill S, Rupprecht H, Frintrop L. Glial cell changes in the corpus callosum in chronically-starved mice. J Eat Disord 2023; 11:227. [PMID: 38111061 PMCID: PMC10726510 DOI: 10.1186/s40337-023-00948-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 12/04/2023] [Indexed: 12/20/2023] Open
Abstract
Anorexia nervosa (AN) is characterized by emaciation, hyperactivity, and amenorrhea. Imaging studies in AN patients have revealed reductions in grey and white matter volume, which correlate with the severity of neuropsychological deficits. However, the cellular basis for the observed brain atrophy is poorly understood. Although distinct hypothalamic centers, including the arcuate nucleus (ARC) are critically involved in regulating feeding behavior, little is known about potential hypothalamic modifications in this disorder. Since glia e.g. astrocytes and microglia influence neuronal circuits, we investigated the glial changes underlying pathophysiology of starvation in the corpus callosum (CC) and hypothalamus. Female mice were given a limited amount of food once a day and had unlimited access to a running wheel until a 20% weight reduction was achieved (acute starvation). This weight reduction was maintained for two weeks to mimic chronic starvation. Immunohistochemistry was used to quantify the density of astrocytes, microglia, oligodendrocytes, and the staining intensity of neuropeptide Y (NPY), a potent orexigenic peptide. Chronic starvation induced a decreased density of OLIG2+ oligodendrocytes, GFAP+ astrocytes, and IBA1+ microglia in the CC. However, the densities of glial cells remained unchanged in the ARC following starvation. Additionally, the staining intensity of NPY increased after both acute and chronic starvation, indicating an increased orexigenic signaling. Chronic starvation induced glial cell changes in the CC in a mouse model of AN suggesting that glia pathophysiology may play a role in the disease.
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Affiliation(s)
- Annelie Zimmermann
- Institute of Anatomy, Rostock University Medical Center, Gertrudenstr. 9, 18057, Rostock, Germany
| | - Natalie Böge
- Institute of Anatomy, Rostock University Medical Center, Gertrudenstr. 9, 18057, Rostock, Germany
| | - Katharina Schuster
- Institute of Anatomy, Rostock University Medical Center, Gertrudenstr. 9, 18057, Rostock, Germany
| | - Anna Staffeld
- Institute of Anatomy, Rostock University Medical Center, Gertrudenstr. 9, 18057, Rostock, Germany
| | - Stephan Lang
- Institute of Anatomy, Rostock University Medical Center, Gertrudenstr. 9, 18057, Rostock, Germany
| | - Sadaf Gill
- Institute of Anatomy, Rostock University Medical Center, Gertrudenstr. 9, 18057, Rostock, Germany
| | - Hanna Rupprecht
- Institute of Anatomy, Rostock University Medical Center, Gertrudenstr. 9, 18057, Rostock, Germany
| | - Linda Frintrop
- Institute of Anatomy, Rostock University Medical Center, Gertrudenstr. 9, 18057, Rostock, Germany.
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Kipp M. Astrocytes: Lessons Learned from the Cuprizone Model. Int J Mol Sci 2023; 24:16420. [PMID: 38003609 PMCID: PMC10671869 DOI: 10.3390/ijms242216420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 11/06/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
A diverse array of neurological and psychiatric disorders, including multiple sclerosis, Alzheimer's disease, and schizophrenia, exhibit distinct myelin abnormalities at both the molecular and histological levels. These aberrations are closely linked to dysfunction of oligodendrocytes and alterations in myelin structure, which may be pivotal factors contributing to the disconnection of brain regions and the resulting characteristic clinical impairments observed in these conditions. Astrocytes, which significantly outnumber neurons in the central nervous system by a five-to-one ratio, play indispensable roles in the development, maintenance, and overall well-being of neurons and oligodendrocytes. Consequently, they emerge as potential key players in the onset and progression of a myriad of neurological and psychiatric disorders. Furthermore, targeting astrocytes represents a promising avenue for therapeutic intervention in such disorders. To gain deeper insights into the functions of astrocytes in the context of myelin-related disorders, it is imperative to employ appropriate in vivo models that faithfully recapitulate specific aspects of complex human diseases in a reliable and reproducible manner. One such model is the cuprizone model, wherein metabolic dysfunction in oligodendrocytes initiates an early response involving microglia and astrocyte activation, culminating in multifocal demyelination. Remarkably, following the cessation of cuprizone intoxication, a spontaneous process of endogenous remyelination occurs. In this review article, we provide a historical overview of studies investigating the responses and putative functions of astrocytes in the cuprizone model. Following that, we list previously published works that illuminate various aspects of the biology and function of astrocytes in this multiple sclerosis model. Some of the studies are discussed in more detail in the context of astrocyte biology and pathology. Our objective is twofold: to provide an invaluable overview of this burgeoning field, and, more importantly, to inspire fellow researchers to embark on experimental investigations to elucidate the multifaceted functions of this pivotal glial cell subpopulation.
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Affiliation(s)
- Markus Kipp
- Institute of Anatomy, Rostock University Medical Center, 18057 Rostock, Germany
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Mitchell JS, Anijärv TE, Levenstein JL, Hermens DF, Lagopoulos J. Excitatory and inhibitory neurometabolites in anorexia nervosa: A systematic review of proton magnetic resonance spectroscopy studies. Neurosci Biobehav Rev 2023; 152:105279. [PMID: 37307945 DOI: 10.1016/j.neubiorev.2023.105279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 06/02/2023] [Accepted: 06/08/2023] [Indexed: 06/14/2023]
Abstract
The dysregulation of excitatory and inhibitory neurotransmission is considered a pathological marker of Anorexia Nervosa (AN), however, no systematic evaluation of the proton Magnetic Resonance Spectroscopy (1H-MRS) literature has been conducted to date. Accordingly, we conducted a systematic review of neurometabolite differences between individuals with AN and healthy controls (HC). A comprehensive database search (until June 2023) identified seven studies meeting inclusion criteria. Samples included adolescents and adults with similar mean age (AN: 22.20 HC: 22.60), and female percentages (AN: 98%; HC: 94%). The review found a considerable need for improving study design and the reporting of MRS sequence parameters and analysis. Reduced glutamate concentrations in the ACC and OCC, and reduced Glx concentrations in the ACC were reported by one and two studies, respectively. Lastly, only one study to date has quantified GABA concentrations, with no significant differences found. In conclusion, there is currently insufficient evidence of excitatory and inhibitory neurometabolites changes in AN. As the 1H-MRS literature in AN increases, the key questions herein proposed must be revisited.
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Affiliation(s)
- Jules S Mitchell
- Thompson Institute, University of Sunshine Coast, 12 Innovation Parkway, Birtinya, 4575 Sunshine Coast, Queensland, Australia.
| | - Toomas E Anijärv
- Thompson Institute, University of Sunshine Coast, 12 Innovation Parkway, Birtinya, 4575 Sunshine Coast, Queensland, Australia
| | - Jacob L Levenstein
- Thompson Institute, University of Sunshine Coast, 12 Innovation Parkway, Birtinya, 4575 Sunshine Coast, Queensland, Australia
| | - Daniel F Hermens
- Thompson Institute, University of Sunshine Coast, 12 Innovation Parkway, Birtinya, 4575 Sunshine Coast, Queensland, Australia
| | - Jim Lagopoulos
- Thompson Institute, University of Sunshine Coast, 12 Innovation Parkway, Birtinya, 4575 Sunshine Coast, Queensland, Australia
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Abstract
Anorexia nervosa is a disorder associated with serious adverse health outcomes, for which there is currently considerable treatment ineffectiveness. Characterised by restrictive eating behaviours, distorted body image perceptions and excessive physical activity, there is growing recognition anorexia nervosa is associated with underlying dysfunction in excitatory and inhibitory neurometabolite metabolism and signalling. This narrative review critically explores the role of N-methyl-D-aspartate receptor-mediated excitatory and inhibitory neurometabolite dysfunction in anorexia nervosa and its associated biomarkers. The existing magnetic resonance spectroscopy literature in anorexia nervosa is reviewed and we outline the brain region-specific neurometabolite changes that have been reported and their connection to anorexia nervosa psychopathology. Considering the proposed role of dysfunctional neurotransmission in anorexia nervosa, the potential utility of zinc supplementation and sub-anaesthetic doses of ketamine in normalising this is discussed with reference to previous research in anorexia nervosa and other neuropsychiatric conditions. The rationale for future research to investigate the combined use of low-dose ketamine and zinc supplementation to potentially extend the therapeutic benefits in anorexia nervosa is subsequently explored and promising biological markers for assessing and potentially predicting treatment response are outlined.
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Abstract
Anorexia is a loss of appetite or an inability to eat and is often associated with eating disorders. However, animal anorexia is physiologically regulated as a part of the life cycle; for instance, during hibernation, migration or incubation. Anorexia nervosa (AN), on the other hand, is a common eating disorder among adolescent females that experience an intense fear of gaining weight due to body image distortion that results in voluntary avoidance of food intake and, thus, severe weight loss. It has been shown that the neurobiology of feeding extends beyond the hypothalamus. The prefrontal cortex (PFC) is involved in food choice and body image perception, both relevant in AN. However, little is known about the neurobiology of AN, and the lack of effective treatments justifies the use of animal models. Glial cells, the dominant population of nerve cells in the central nervous system, are key in maintaining brain homeostasis. Accordingly, recent studies suggest that glial function may be compromised by anorexia. In this review, we summarize recent findings about anorexia and glial cells.
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