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Gutierrez-Castellanos N, Dias IC, Husain BFA, Lima S. Functional diversity along the anteroposterior axis of the ventromedial hypothalamus. J Neuroendocrinol 2024:e13447. [PMID: 39253818 DOI: 10.1111/jne.13447] [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: 05/12/2024] [Revised: 08/14/2024] [Accepted: 08/28/2024] [Indexed: 09/11/2024]
Abstract
Innate behaviors ensure animal survival and reproductive success. Defending their territory, escaping from predators or mating with a sexual partner, are fundamental behaviors determining the ecological fitness of individuals. Remarkably, all these behaviors share a common neural substrate, as they are under the control of the ventromedial hypothalamus (VMH). Decades of research have contributed to understanding the exquisite diversity of functional ensembles underlying the wide array of functions that the VMH carries out. These functional ensembles are usually distributed throughout the dorsoventral and mediolateral axes of this nucleus. However, increasing evidence is bringing to attention the functional diversity of the VMH across its anteroposterior axis. In this review, we will overview our current understanding of how different ensembles within the VMH control a wide array of animal behaviors, emphasizing the newly discovered roles for its anterior subdivision in the context of conspecific self-defense.
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Affiliation(s)
| | - Inês C Dias
- Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal
| | | | - Susana Lima
- Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal
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Zago AM, Carvalho FB, Rahmeier FL, Santin M, Guimarães GR, Gutierres JM, da C Fernandes M. Exendin-4 Prevents Memory Loss and Neuronal Death in Rats with Sporadic Alzheimer-Like Disease. Mol Neurobiol 2024; 61:2631-2652. [PMID: 37919602 DOI: 10.1007/s12035-023-03698-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 10/06/2023] [Indexed: 11/04/2023]
Abstract
This study investigated the neuroprotective effects of exendin-4 (EXE-4), an analog of the glucagon-like peptide 1 receptor (GLP-1R) on memory and on the neuronal populations that constitute the hippocampus of rats submitted to a sporadic dementia of Alzheimer's type (SDAT). Male Wistar rats received streptozotocin (STZ icv, 3 mg/kg diluted in aCFS, 5 µl/ventricle) and were treated for 21 days with EXE-4 (10 µg/kg, ip; saline as the vehicle). Four groups were formed: vehicle, EXE-4, STZ, and STZ + EXE-4. The groups were submitted to Y-Maze (YM), object recognition (ORT), and object displacement tasks (ODT) to assess learning and memory. The brains were used for immunohistochemical and immunofluorescent techniques with antibodies to NeuN, cleaved caspase-3 (CC3), PCNA, doublecortin (DCX), synaptophysin (SYP), and insulin receptor (IR). STZ worsened spatial memory in the YMT, as well as short-term (STM) and long-term (LTM) memories in the ORT and ODT, respectively. EXE-4 protected against memory impairment in STZ animals. STZ reduced mature neuron density (NeuN) and increased cell apoptosis (CC3) in the DG, CA1, and CA3. EXE-4 protected against neuronal death in all regions. EXE-4 increased PCNA+ cells in all regions of the hippocampus, and STZ attenuated this effect. STZ reduced neurogenesis in DG per se as well as synaptogenesis induced by EXE-4. EXE-4 increased immunoreactivity to IR in the CA1. From these findings, EXE-4 showed a beneficial effect on hippocampal pyramidal and granular neurons in the SDAT showing anti-apoptotic properties and promoting cell proliferation. In parallel, EXE-4 preserved the memory of SDAT rats. EXE-4 appears to enhance synapses at CA3 and DG. In conclusion, these data indicate that agonists to GLP-1R have a beneficial effect on hippocampal neurons in AD.
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Affiliation(s)
- Adriana M Zago
- Graduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Sarmento Leite, 245, Room 514, Building 3. CEP 90050-170, Porto Alegre, RS, Brazil
| | - Fabiano B Carvalho
- Graduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Sarmento Leite, 245, Room 514, Building 3. CEP 90050-170, Porto Alegre, RS, Brazil.
| | - Francine L Rahmeier
- Graduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Sarmento Leite, 245, Room 514, Building 3. CEP 90050-170, Porto Alegre, RS, Brazil
| | - Marta Santin
- Graduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Sarmento Leite, 245, Room 514, Building 3. CEP 90050-170, Porto Alegre, RS, Brazil
| | - Giuliano R Guimarães
- Graduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Sarmento Leite, 245, Room 514, Building 3. CEP 90050-170, Porto Alegre, RS, Brazil
| | - Jessié M Gutierres
- Graduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Sarmento Leite, 245, Room 514, Building 3. CEP 90050-170, Porto Alegre, RS, Brazil
| | - Marilda da C Fernandes
- Graduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Sarmento Leite, 245, Room 514, Building 3. CEP 90050-170, Porto Alegre, RS, Brazil.
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Martin H, Coursan A, Lallement J, Di Miceli M, Kandiah J, Raho I, Buttler J, Guilloux JP, De Deurwaerdere P, Layé S, Routh VH, Guiard BP, Magnan C, Cruciani-Guglielmacci C, Fioramonti X. Serotonergic neurons are involved in the counter-regulatory response to hypoglycemia. J Neuroendocrinol 2023; 35:e13344. [PMID: 37857383 DOI: 10.1111/jne.13344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/30/2023] [Accepted: 09/12/2023] [Indexed: 10/21/2023]
Abstract
OBJECTIVES Intensive insulin therapy provides optimal glycemic control in patients with diabetes. However, intensive insulin therapy causes so-called iatrogenic hypoglycemia as a major adverse effect. The ventromedial hypothalamus (VMH) has been described as the primary brain area initiating the counter-regulatory response (CRR). Nevertheless, the VMH receives projections from other brain areas which could participate in the regulation of the CRR. In particular, studies suggest a potential role of the serotonin (5-HT) network. Thus, the objective of this study was to determine the contribution of 5-HT neurons in CRR control. METHODS Complementary approaches have been used to test this hypothesis in quantifying the level of 5-HT in several brain areas by HPLC in response to insulin-induced hypoglycemia, measuring the electrical activity of dorsal raphe (DR) 5-HT neurons in response to insulin or decreased glucose level by patch-clamp electrophysiology; and measuring the CRR hormone glucagon as an index of the CRR to the modulation of the activity of 5-HT neurons using pharmacological or pharmacogenetic approaches. RESULTS HPLC measurements show that the 5HIAA/5HT ratio is increased in several brain regions including the VMH in response to insulin-induced hypoglycemia. Patch-clamp electrophysiological recordings show that insulin, but not decreased glucose level, increases the firing frequency of DR 5-HT neurons in the DR. In vivo, both the pharmacological inhibition of 5-HT neurons by intraperitoneal injection of the 5-HT1A receptor agonist 8-OH-DPAT or the chemogenetic inhibition of these neurons reduce glucagon secretion, suggesting an impaired CRR. CONCLUSION Taken together, these data highlight a new neuronal network involved in the regulation of the CRR. In particular, this study shows that DR 5-HT neurons detect iatrogenic hypoglycemia in response to the increased insulin level and may play an important role in the regulation of CRR.
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Affiliation(s)
- Hugo Martin
- Université Bordeaux, INRAE, Bordeaux INP, NutriNeuro, UMR 1286, Bordeaux, France
| | - Adeline Coursan
- Université Bordeaux, INRAE, Bordeaux INP, NutriNeuro, UMR 1286, Bordeaux, France
| | | | - Mathieu Di Miceli
- Worcester Biomedical Research Group, School of Science and the Environment, University of Worcester, Worcester, UK
| | - Janany Kandiah
- Université Paris Cité, BFA, UMR 8251, CNRS, Paris, France
| | - Ilyès Raho
- Université Paris Cité, BFA, UMR 8251, CNRS, Paris, France
| | - Jasmine Buttler
- INCIA, UMR CNRS, Bordeaux University, Neurocampus, Bordeaux, France
| | | | | | - Sophie Layé
- Université Bordeaux, INRAE, Bordeaux INP, NutriNeuro, UMR 1286, Bordeaux, France
| | - Vanessa H Routh
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, New Jersey, USA
| | - Bruno P Guiard
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Toulouse, France
| | | | | | - Xavier Fioramonti
- Université Bordeaux, INRAE, Bordeaux INP, NutriNeuro, UMR 1286, Bordeaux, France
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Jo D, Yoon G, Lim Y, Kim Y, Song J. Profiling and Cellular Analyses of Obesity-Related circRNAs in Neurons and Glia under Obesity-like In Vitro Conditions. Int J Mol Sci 2023; 24:ijms24076235. [PMID: 37047207 PMCID: PMC10094513 DOI: 10.3390/ijms24076235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 03/23/2023] [Accepted: 03/24/2023] [Indexed: 03/29/2023] Open
Abstract
Recent evidence indicates that the pathogenesis of neurodegenerative diseases, including Alzheimer’s disease, is associated with metabolic disorders such as diabetes and obesity. Various circular RNAs (circRNAs) have been found in brain tissues and recent studies have suggested that circRNAs are related to neuropathological mechanisms in the brain. However, there is a lack of interest in the involvement of circRNAs in metabolic imbalance-related neuropathological problems until now. Herein we profiled and analyzed diverse circRNAs in mouse brain cell lines (Neuro-2A neurons, BV-2 microglia, and C8-D1a astrocytes) exposed to obesity-related in vitro conditions (high glucose, high insulin, and high levels of tumor necrosis factor-alpha, interleukin 6, palmitic acid, linoleic acid, and cholesterol). We observed that various circRNAs were differentially expressed according to cell types with many of these circRNAs conserved in humans. After suppressing the expression of these circRNAs using siRNAs, we observed that these circRNAs regulate genes related to inflammatory responses, formation of synaptic vesicles, synaptic density, and fatty acid oxidation in neurons; scavenger receptors in microglia; and fatty acid signaling, inflammatory signaling cyto that may play important roles in metabolic disorders associated with neurodegenerative diseases.
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Affiliation(s)
- Danbi Jo
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
| | - Gwangho Yoon
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
| | - Yeonghwan Lim
- Department of Biochemistry, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
| | - Youngkook Kim
- Department of Biochemistry, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
- Correspondence: (Y.K.); (J.S.)
| | - Juhyun Song
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
- Correspondence: (Y.K.); (J.S.)
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Rawlinson S, Reichenbach A, Clarke RE, Nuñez-Iglesias J, Dempsey H, Lockie SH, Andrews ZB. In Vivo Photometry Reveals Insulin and 2-Deoxyglucose Maintain Prolonged Inhibition of VMH Vglut2 Neurons in Male Mice. Endocrinology 2022; 163:6631280. [PMID: 35788848 DOI: 10.1210/endocr/bqac095] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Indexed: 11/19/2022]
Abstract
The ventromedial hypothalamic (VMH) nucleus is a well-established hub for energy and glucose homeostasis. In particular, VMH neurons are thought to be important for initiating the counterregulatory response to hypoglycemia, and ex vivo electrophysiology and immunohistochemistry data indicate a clear role for VMH neurons in sensing glucose concentration. However, the temporal response of VMH neurons to physiologically relevant changes in glucose availability in vivo has been hampered by a lack of available tools for measuring neuronal activity over time. Since the majority of neurons within the VMH are glutamatergic and can be targeted using the vesicular glutamate transporter Vglut2, we expressed cre-dependent GCaMP7s in Vglut2 cre mice and examined the response profile of VMH to intraperitoneal injections of glucose, insulin, and 2-deoxyglucose (2DG). We show that reduced available glucose via insulin-induced hypoglycemia and 2DG-induced glucoprivation, but not hyperglycemia induced by glucose injection, inhibits VMH Vglut2 neuronal population activity in vivo. Surprisingly, this inhibition was maintained for at least 45 minutes despite prolonged hypoglycemia and initiation of a counterregulatory response. Thus, although VMH stimulation, via pharmacological, electrical, or optogenetic approaches, is sufficient to drive a counterregulatory response, our data suggest VMH Vglut2 neurons are not the main drivers required to do so, since VMH Vglut2 neuronal population activity remains suppressed during hypoglycemia and glucoprivation.
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Affiliation(s)
- Sasha Rawlinson
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Alex Reichenbach
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Rachel E Clarke
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425, USA
| | - Juan Nuñez-Iglesias
- Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Clayton, Victoria, 3800, Australia
| | - Harry Dempsey
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Sarah H Lockie
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Zane B Andrews
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria, 3800, Australia
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Staricoff EO, Evans ML. Recent advances in understanding hypothalamic control of defensive responses to hypoglycaemia. CURRENT OPINION IN ENDOCRINE AND METABOLIC RESEARCH 2022; 24:100353. [PMID: 39183767 PMCID: PMC11339540 DOI: 10.1016/j.coemr.2022.100353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
Maintenance of normal blood glucose is important for survival. In particular, brain function is dependent on circulating glucose. In health, a series of powerful counterregulatory defences operate to prevent/limit hypoglycaemia. These defences are altered to varying degrees in diabetes and in particular, a subset of people with diabetes can develop profound deficits in these defences placing them at increased risk of suffering episodes of severe hypoglycaemia. Brain is an important controller of glucose homeostasis and developments in molecular techniques have allowed the neurocircuitry of a number of important centrally-controlled homeostatic processes such as energy balance, thirst and thermoregulation to be defined. This review describes how some of these advances have allowed a better understanding of the neuronal/brain ensembles which help protect against hypoglycaemia.
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Affiliation(s)
- Emily O. Staricoff
- Wellcome Trust MRC Institute of Metabolic Science, University of Cambridge, UK
| | - Mark L. Evans
- Wellcome Trust MRC Institute of Metabolic Science, University of Cambridge, UK
- Department of Medicine, Addenbrookes NIHR Biomedical Campus, Cambridge, UK
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Tu L, Fukuda M, Tong Q, Xu Y. The ventromedial hypothalamic nucleus: watchdog of whole-body glucose homeostasis. Cell Biosci 2022; 12:71. [PMID: 35619170 PMCID: PMC9134642 DOI: 10.1186/s13578-022-00799-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 04/25/2022] [Indexed: 02/06/2023] Open
Abstract
The brain, particularly the ventromedial hypothalamic nucleus (VMH), has been long known for its involvement in glucose sensing and whole-body glucose homeostasis. However, it is still not fully understood how the brain detects and responds to the changes in the circulating glucose levels, as well as brain-body coordinated control of glucose homeostasis. In this review, we address the growing evidence implicating the brain in glucose homeostasis, especially in the contexts of hypoglycemia and diabetes. In addition to neurons, we emphasize the potential roles played by non-neuronal cells, as well as extracellular matrix in the hypothalamus in whole-body glucose homeostasis. Further, we review the ionic mechanisms by which glucose-sensing neurons sense fluctuations of ambient glucose levels. We also introduce the significant implications of heterogeneous neurons in the VMH upon glucose sensing and whole-body glucose homeostasis, in which sex difference is also addressed. Meanwhile, research gaps have also been identified, which necessities further mechanistic studies in future.
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Affiliation(s)
- Longlong Tu
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street #8066, Houston, TX, 77030, USA
| | - Makoto Fukuda
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street #8066, Houston, TX, 77030, USA
| | - Qingchun Tong
- Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Yong Xu
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street #8066, Houston, TX, 77030, USA.
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
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Hypothalamic Expression of Neuropeptide Y (NPY) and Pro-OpioMelanoCortin (POMC) in Adult Male Mice Is Affected by Chronic Exposure to Endocrine Disruptors. Metabolites 2021; 11:metabo11060368. [PMID: 34207679 PMCID: PMC8228876 DOI: 10.3390/metabo11060368] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 06/04/2021] [Accepted: 06/06/2021] [Indexed: 02/07/2023] Open
Abstract
In the arcuate nucleus, neuropeptide Y (NPY) neurons, increase food intake and decrease energy expenditure, and control the activity of pro-opiomelanocortin (POMC) neurons, that decrease food intake and increase energy expenditure. Both systems project to other hypothalamic nuclei such as the paraventricular and dorsomedial hypothalamic nuclei. Endocrine disrupting chemicals (EDCs) are environmental contaminants that alter the endocrine system causing adverse health effects in an intact organism or its progeny. We investigated the effects of long-term exposure to some EDCs on the hypothalamic NPY and POMC systems of adult male mice that had been previously demonstrated to be a target of some of these EDCs after short-term exposure. Animals were chronically fed for four months with a phytoestrogen-free diet containing two different concentrations of bisphenol A, diethylstilbestrol, tributyltin, or E2. At the end, brains were processed for NPY and POMC immunohistochemistry and quantitatively analyzed. In the arcuate and dorsomedial nuclei, both NPY and POMC immunoreactivity showed a statistically significant decrease. In the paraventricular nucleus, only the NPY system was affected, while the POMC system was not affected. Finally, in the VMH the NPY system was affected whereas no POMC immunoreactive material was observed. These results indicate that adult exposure to different EDCs may alter the hypothalamic circuits that control food intake and energy metabolism.
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