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Mavanji V, Pomonis BL, Shekels L, Kotz CM. Interactions between Lateral Hypothalamic Orexin and Dorsal Raphe Circuitry in Energy Balance. Brain Sci 2024; 14:464. [PMID: 38790443 PMCID: PMC11117928 DOI: 10.3390/brainsci14050464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 04/30/2024] [Accepted: 05/04/2024] [Indexed: 05/26/2024] Open
Abstract
Orexin/hypocretin terminals innervate the dorsal raphe nucleus (DRN), which projects to motor control areas important for spontaneous physical activity (SPA) and energy expenditure (EE). Orexin receptors are expressed in the DRN, and obesity-resistant (OR) rats show higher expression of these receptors in the DRN and elevated SPA/EE. We hypothesized that orexin-A in the DRN enhances SPA/EE and that DRN-GABA modulates the effect of orexin-A on SPA/EE. We manipulated orexin tone in the DRN either through direct injection of orexin-A or through the chemogenetic activation of lateral-hypothalamic (LH) orexin neurons. In the orexin neuron activation experiment, fifteen minutes prior to the chemogenetic activation of orexin neurons, the mice received either the GABA-agonist muscimol or antagonist bicuculline injected into the DRN, and SPA/EE was monitored for 24 h. In a separate experiment, orexin-A was injected into the DRN to study the direct effect of DRN orexin on SPA/EE. We found that the activation of orexin neurons elevates SPA/EE, and manipulation of GABA in the DRN does not alter the SPA response to orexin neuron activation. Similarly, intra-DRN orexin-A enhanced SPA and EE in the mice. These results suggest that orexin-A in the DRN facilitates negative energy balance by increasing physical activity-induced EE, and that modulation of DRN orexin-A is a potential strategy to promote SPA and EE.
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Affiliation(s)
- Vijayakumar Mavanji
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Brianna L. Pomonis
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Laurie Shekels
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Catherine M. Kotz
- Research Service, Veterans Affairs Health Care System, Minneapolis, MN 55417, USA; (V.M.); (B.L.P.); (L.S.)
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN 55455, USA
- Geriatric Research, Education and Clinical Center, Minneapolis VA Health Care System, Minneapolis, MN 55417, USA
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Maxwell ND, Smiley CE, Sadek AT, Loyo-Rosado FZ, Giles DC, Macht VA, Woodruff JL, Taylor DL, Wilson SP, Fadel JR, Reagan LP, Grillo CA. Leptin activation of dorsal raphe neurons inhibits feeding behavior. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.24.538086. [PMID: 37162932 PMCID: PMC10168215 DOI: 10.1101/2023.04.24.538086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Leptin is a homeostatic regulatory element that signals the presence of energy stores -in the form of adipocytes-which ultimately reduces food intake and increases energy expenditure. Similarly, serotonin (5-HT), a signaling molecule found in both the central and peripheral nervous systems, also regulates food intake. Here we use a combination of pharmacological manipulations, optogenetics, retrograde tracing, and in situ hybridization, combined with behavioral endpoints to physiologically and anatomically identify a novel leptin-mediated pathway between 5-HT neurons in the dorsal raphe nucleus (DRN) and hypothalamic arcuate nucleus (ARC) that controls food intake. In this study, we show that microinjecting leptin directly into the DRN reduces food intake in male Sprague-Dawley rats. This effect is mediated by leptin-receptor expressing neurons in the DRN as selective optogenetic activation of these neurons at either their ARC terminals or DRN cell bodies also reduces food intake. Anatomically, we identified a unique population of serotonergic raphe neurons expressing leptin receptors that send projections to the ARC. Finally, by utilizing in vivo microdialysis and high-performance liquid chromatography, we show that leptin administration to the DRN increases 5-HT efflux into the ARC. Overall, this study identifies a novel circuit for leptin-mediated control of food intake through a DRN-ARC pathway, utilizing 5-HT as a mechanism to control feeding behavior. Characterization of this new pathway creates opportunities for understanding how the brain controls eating behavior, as well as opens alternative routes for the treatment of eating disorders. Significance Leptin and serotonin both play a vital role in the regulation of food intake, yet there is still uncertainty in how these two molecules interact to control appetite. The purpose of this study is to further understand the anatomical and functional connections between leptin receptor expressing neurons in the dorsal raphe nucleus, the main source of serotonin, and the arcuate nucleus of the hypothalamus, and how serotonin plays a role in this pathway to reduce food intake. Insight gained from this study will contribute to a more thorough understanding of the networks that regulate food intake, and open alternative avenues for the development of treatments for obesity and eating disorders.
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Behera CK, Joshi A, Wang DH, Sharp T, Wong-Lin K. Degeneracy and stability in neural circuits of dopamine and serotonin neuromodulators: A theoretical consideration. Front Comput Neurosci 2023; 16:950489. [PMID: 36761394 PMCID: PMC9905743 DOI: 10.3389/fncom.2022.950489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 12/30/2022] [Indexed: 01/26/2023] Open
Abstract
Degenerate neural circuits perform the same function despite being structurally different. However, it is unclear whether neural circuits with interacting neuromodulator sources can themselves degenerate while maintaining the same neuromodulatory function. Here, we address this by computationally modeling the neural circuits of neuromodulators serotonin and dopamine, local glutamatergic and GABAergic interneurons, and their possible interactions, under reward/punishment-based conditioning tasks. The neural modeling is constrained by relevant experimental studies of the VTA or DRN system using, e.g., electrophysiology, optogenetics, and voltammetry. We first show that a single parsimonious, sparsely connected neural circuit model can recapitulate several separate experimental findings that indicated diverse, heterogeneous, distributed, and mixed DRNVTA neuronal signaling in reward and punishment tasks. The inability of this model to recapitulate all observed neuronal signaling suggests potentially multiple circuits acting in parallel. Then using computational simulations and dynamical systems analysis, we demonstrate that several different stable circuit architectures can produce the same observed network activity profile, hence demonstrating degeneracy. Due to the extensive D2-mediated connections in the investigated circuits, we simulate the D2 receptor agonist by increasing the connection strengths emanating from the VTA DA neurons. We found that the simulated D2 agonist can distinguish among sub-groups of the degenerate neural circuits based on substantial deviations in specific neural populations' activities in reward and punishment conditions. This forms a testable model prediction using pharmacological means. Overall, this theoretical work suggests the plausibility of degeneracy within neuromodulator circuitry and has important implications for the stable and robust maintenance of neuromodulatory functions.
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Affiliation(s)
- Chandan K. Behera
- Intelligent Systems Research Centre, School of Computing, Engineering and Intelligent Systems, Ulster University, Derry∼Londonderry, United Kingdom,*Correspondence: Chandan K. Behera,
| | - Alok Joshi
- Intelligent Systems Research Centre, School of Computing, Engineering and Intelligent Systems, Ulster University, Derry∼Londonderry, United Kingdom
| | - Da-Hui Wang
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China,School of Systems Science, Beijing Normal University, Beijing, China
| | - Trevor Sharp
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - KongFatt Wong-Lin
- Intelligent Systems Research Centre, School of Computing, Engineering and Intelligent Systems, Ulster University, Derry∼Londonderry, United Kingdom,KongFatt Wong-Lin,
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Aklan I, Sayar-Atasoy N, Deng F, Kim H, Yavuz Y, Rysted J, Laule C, Davis D, Li Y, Atasoy D. Dorsal raphe serotonergic neurons suppress feeding through redundant forebrain circuits. Mol Metab 2023; 69:101676. [PMID: 36682413 PMCID: PMC9923194 DOI: 10.1016/j.molmet.2023.101676] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 12/04/2022] [Accepted: 01/13/2023] [Indexed: 01/21/2023] Open
Abstract
OBJECTIVE Serotonin (5HT) is a well-known anorexigenic molecule, and 5HT neurons of dorsal raphe nucleus (DRN) have been implicated in suppression of feeding; however, the downstream circuitry is poorly understood. Here we explored major projections of DRN5HT neurons for their capacity to modulate feeding. METHODS We used optogenetics to selectively activate DRN5HT axonal projections in hypothalamic and extrahypothalamic areas and monitored food intake. We next used fiber photometry to image the activity dynamics of DRN5HT axons and 5HT levels in projection areas in response feeding and metabolic hormones. Finally, we used electrophysiology to determine how DRN5HT axons affect downstream neuron activity. RESULTS We found that selective activation of DRN5HT axons in (DRN5HT → LH) and (DRN5HT → BNST) suppresses feeding whereas activating medial hypothalamic projections has no effect. Using in vivo imaging, we found that food access and satiety hormones activate DRN5HT projections to LH where they also rapidly increase extracellular 5HT levels. Optogenetic mapping revealed that DRN5HT → LHvGAT and DRN5HT → LHvGlut2 connections are primarily inhibitory and excitatory respectively. Further, in addition to its direct action on LH neurons, we found that 5HT suppresses GABA release from presynaptic terminals arriving from AgRP neurons. CONCLUSIONS These findings define functionally redundant forebrain circuits through which DRN5HT neurons suppress feeding and reveal that these projections can be modulated by metabolic hormones.
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Affiliation(s)
- Iltan Aklan
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Nilufer Sayar-Atasoy
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Fei Deng
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
| | - Hyojin Kim
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Yavuz Yavuz
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA,Department of Physiology, School of Medicine, Yeditepe University, Istanbul, Turkey
| | - Jacob Rysted
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Connor Laule
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Debbie Davis
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
| | - Deniz Atasoy
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA; Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA; Fraternal Order of Eagles Diabetes Research Center (FOEDRC), Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
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Gołyszny M, Zieliński M, Paul-Samojedny M, Filipczyk Ł, Pałasz A, Obuchowicz E. Escitalopram alters the hypothalamic OX system but does not affect its up-regulation induced by early-life stress in adult rats. Neurosci Res 2022; 180:58-71. [PMID: 35219722 DOI: 10.1016/j.neures.2022.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 02/07/2022] [Accepted: 02/23/2022] [Indexed: 01/06/2023]
Abstract
We hypothesized that there is a relationship between the orexinergic system (OX) alterations and changes elicited by escitalopram or venlafaxine in adult rats subjected to maternal separation (MS). This animal model of childhood adversity induces long-lasting consequences in adult physiology and behavior. Male Wistar rats from the control and MS groups were injected with escitalopram or venlafaxine (10 mg/kg) IP from postnatal day (PND) 69-89. Adult rats were subjected to behavioral assessment, estimation of hypothalamic-pituitary-adrenal (HPA) axis activity and analysis of the OX system (quantitative PCR and immunohistochemistry) in the hypothalamus and amygdala. MS caused anxiety- and depressive-like behavior, endocrine stress-related response, and up-regulation of the OX system in the hypothalamus. Escitalopram, but not venlafaxine, increased the activity of hypothalamic OX system in the control rats and both drugs had no effect on OXs in the MS group. The disturbed signaling of the OX pathway may be significant for harmful long-term consequences of early-life stress. Our data show that the normal brain and brain altered by MS respond differently to escitalopram. Presumably, anti-anxiety and antidepressant effects of this drug do not depend on the activity of hypothalamic OX system.
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Affiliation(s)
- Miłosz Gołyszny
- Department of Pharmacology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, Medyków 18 street, Katowice 40-752, Poland.
| | - Michał Zieliński
- Department of Pharmacology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, Medyków 18 street, Katowice 40-752, Poland
| | - Monika Paul-Samojedny
- Department of Medical Genetics, Faculty of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia, Jedności 8, Sosnowiec 41-200, Poland
| | - Łukasz Filipczyk
- Department of Histology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, Medyków 18 street, Katowice 40-752, Poland
| | - Artur Pałasz
- Department of Histology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, Medyków 18 street, Katowice 40-752, Poland
| | - Ewa Obuchowicz
- Department of Pharmacology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, Medyków 18 street, Katowice 40-752, Poland
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Lo Y, Yi PL, Hsiao YT, Chang FC. Hypocretin in locus coeruleus and dorsal raphe nucleus mediates inescapable footshock stimulation (IFS)-induced REM sleep alteration. Sleep 2021; 45:6490200. [PMID: 34969120 DOI: 10.1093/sleep/zsab301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 11/12/2021] [Indexed: 11/14/2022] Open
Abstract
Hypocretin (hcrt) is a stress-reacting neuropeptide mediating arousal and energy homeostasis. An inescapable footshock stimulation (IFS) could initiate the hcrt release from the lateral hypothalamus (LHA) and suppresses rapid eye movement (REM) sleep in rodents. However, the effects of the IFS-induced hcrts on REM-off nuclei, the locus coeruleus (LC) and dorsal raphe nucleus (DRN), remained unclear. We hypothesized that the hcrt projections from the LHA to LC or DRN mediate IFS-induced sleep disruption. Our results demonstrated that the IFS increased hcrt expression and the neuronal activities in the LHA, hypothalamus, brainstem, thalamus, and amygdala. Suppressions of REM sleep and slow wave activity during non-REM (NREM) sleep caused by the high expression of hcrts were blocked when a non-specific and dual hcrt receptor antagonist was administered into the LC or DRN. Furthermore, the IFS also caused an elevated innate anxiety, but was limitedly influenced by the hcrt antagonist. This result suggests that the increased hcrt concentrations in the LC and DRN mediate stress-induced sleep disruptions and might partially involve IFS-induced anxiety.
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Affiliation(s)
- Yun Lo
- Department of Veterinary Medicine, School of Veterinary Medicine, National Taiwan, University, Taipei, Taiwan
| | - Pei-Lu Yi
- Department of Sport Management, College of Tourism, Leisure and Sports, Aletheia, University, New Taipei City, Taiwan
| | - Yi-Tse Hsiao
- Department of Veterinary Medicine, School of Veterinary Medicine, National Taiwan, University, Taipei, Taiwan
| | - Fang-Chia Chang
- Department of Veterinary Medicine, School of Veterinary Medicine, National Taiwan, University, Taipei, Taiwan.,Graduate Institute of Brain & Mind Sciences, College of Medicine, National Taiwan, University, Taipei, Taiwan.,Graduate Institute of Acupuncture Science, College of Chinese Medicine, China, Medical University, Taichung, Taiwan.,Department of Medicine, College of Medicine, China Medical University, Taichung, Taiwan
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7
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van Galen KA, Ter Horst KW, Serlie MJ. Serotonin, food intake, and obesity. Obes Rev 2021; 22:e13210. [PMID: 33559362 PMCID: PMC8243944 DOI: 10.1111/obr.13210] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/28/2020] [Accepted: 12/28/2020] [Indexed: 12/16/2022]
Abstract
The role of serotonin in food intake has been studied for decades. Food intake is mainly regulated by two brain circuitries: (i) the homeostatic circuitry, which matches energy intake to energy expenditure, and (ii) the hedonic circuitry, which is involved in rewarding and motivational aspects of energy consumption. In the homeostatic circuitry, serotonergic signaling contributes to the integration of metabolic signals that convey the body's energy status and facilitates the ability to suppress food intake when homeostatic needs have been met. In the hedonic circuitry, serotonergic signaling may reduce reward-related, motivational food consumption. In contrast, peripherally acting serotonin promotes energy absorption and storage. Disturbed serotonergic signaling is associated with obesity, emphasizing the importance to understand the role of serotonergic signaling in food intake. However, unraveling the serotonin-mediated regulation of food intake is complex, as the effects of serotonergic signaling in different brain regions depend on the regional expression of serotonin receptor subtypes and downstream effects via connections to other brain regions. We therefore provide an overview of the effects of serotonergic signaling in brain regions of the homeostatic and hedonic regulatory systems on food intake. Furthermore, we discuss the disturbances in serotonergic signaling in obesity and its potential therapeutic implications.
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Affiliation(s)
- Katy A van Galen
- Department of Endocrinology and Metabolism, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Kasper W Ter Horst
- Department of Endocrinology and Metabolism, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Mireille J Serlie
- Department of Endocrinology and Metabolism, Amsterdam University Medical Centers, Amsterdam, The Netherlands
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Romanova IV, Morina IY, Shpakov AO. Localization of 5-HT2C and
5-HT1B Serotonin Receptors in Orexinergic
Neurons of the Hypothlamic Perifornical Area of Rodents. J EVOL BIOCHEM PHYS+ 2020. [DOI: 10.1134/s0022093020020076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Joshi A, Wang DH, Watterson S, McClean PL, Behera CK, Sharp T, Wong-Lin K. Opportunities for multiscale computational modelling of serotonergic drug effects in Alzheimer's disease. Neuropharmacology 2020; 174:108118. [PMID: 32380022 PMCID: PMC7322519 DOI: 10.1016/j.neuropharm.2020.108118] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 04/13/2020] [Accepted: 04/27/2020] [Indexed: 12/17/2022]
Abstract
Alzheimer's disease (AD) is an age-specific neurodegenerative disease that compromises cognitive functioning and impacts the quality of life of an individual. Pathologically, AD is characterised by abnormal accumulation of beta-amyloid (Aβ) and hyperphosphorylated tau protein. Despite research advances over the last few decades, there is currently still no cure for AD. Although, medications are available to control some behavioural symptoms and slow the disease's progression, most prescribed medications are based on cholinesterase inhibitors. Over the last decade, there has been increased attention towards novel drugs, targeting alternative neurotransmitter pathways, particularly those targeting serotonergic (5-HT) system. In this review, we focused on 5-HT receptor (5-HTR) mediated signalling and drugs that target these receptors. These pathways regulate key proteins and kinases such as GSK-3 that are associated with abnormal levels of Aβ and tau in AD. We then review computational studies related to 5-HT signalling pathways with the potential for providing deeper understanding of AD pathologies. In particular, we suggest that multiscale and multilevel modelling approaches could potentially provide new insights into AD mechanisms, and towards discovering novel 5-HTR based therapeutic targets. Alzheimer's disease (AD) drug treatment is limited, and alternatives are needed. Serotonin (5-HT) mediated signalling pathways may regulate Aβ and tau levels. 5-HT based drugs have the potential to provide as novel therapeutics for AD. Complex 5-HT signalling mechanisms for AD and related drugs hinder understanding. Multiscale models may offer insights into mechanisms and therapeutic targets.
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Affiliation(s)
- Alok Joshi
- Intelligent Systems Research Centre, Ulster University, Derry~Londonderry, Northern Ireland, UK.
| | - Da-Hui Wang
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China; School of System Science, Beijing Normal University, Beijing, China
| | - Steven Watterson
- Northern Ireland Centre for Stratified Medicine, Biomedical Sciences Research Institute, Ulster University, Derry~Londonderry, Northern Ireland, UK
| | - Paula L McClean
- Northern Ireland Centre for Stratified Medicine, Biomedical Sciences Research Institute, Ulster University, Derry~Londonderry, Northern Ireland, UK
| | - Chandan K Behera
- Intelligent Systems Research Centre, Ulster University, Derry~Londonderry, Northern Ireland, UK
| | - Trevor Sharp
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - KongFatt Wong-Lin
- Intelligent Systems Research Centre, Ulster University, Derry~Londonderry, Northern Ireland, UK.
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10
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Tanaka S, Higuchi M, Seki S, Enomoto A, Kogo M. Orexins modulate membrane excitability in rat trigeminal motoneurons. J Oral Sci 2020; 62:265-270. [DOI: 10.2334/josnusd.19-0141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Affiliation(s)
- Susumu Tanaka
- First Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University
| | - Masataka Higuchi
- First Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University
| | - Soju Seki
- First Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University
| | - Akifumi Enomoto
- Department of Oral and Maxillofacial Surgery, Faculty of Medicine, Kindai University
| | - Mikihiko Kogo
- First Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University
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11
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Abstract
Sleep and circadian rhythms are regulated across multiple functional, spatial and temporal levels: from genes to networks of coupled neurons and glial cells, to large scale brain dynamics and behaviour. The dynamics at each of these levels are complex and the interaction between the levels is even more so, so research have mostly focused on interactions within the levels to understand the underlying mechanisms—the so-called reductionist approach. Mathematical models were developed to test theories of sleep regulation and guide new experiments at each of these levels and have become an integral part of the field. The advantage of modelling, however, is that it allows us to simulate and test the dynamics of complex biological systems and thus provides a tool to investigate the connections between the different levels and study the system as a whole. In this paper I review key models of sleep developed at different physiological levels and discuss the potential for an integrated systems biology approach for sleep regulation across these levels. I also highlight the necessity of building mechanistic connections between models of sleep and circadian rhythms across these levels.
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Affiliation(s)
- Svetlana Postnova
- School of Physics, University of Sydney, Sydney 2006, NSW, Australia;
- Center of Excellence for Integrative Brain Function, University of Sydney, Sydney 2006, NSW, Australia
- Charles Perkins Center, University of Sydney, Sydney 2006, NSW, Australia
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12
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da Silva Soares R, Falconi-Sobrinho LL, dos Anjos-Garcia T, Coimbra NC. 5-Hydroxytryptamine 2A receptors of the dorsal raphe nucleus modulate panic-like behaviours and mediate fear-induced antinociception elicited by neuronal activation in the central nucleus of the inferior colliculus. Behav Brain Res 2019; 357-358:71-81. [DOI: 10.1016/j.bbr.2017.07.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 06/14/2017] [Accepted: 07/15/2017] [Indexed: 12/26/2022]
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13
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Abstract
Purpose of Review The aim of this review was to summarize collected data on the role of orexin and orexin neurons in the control of sleep and blood pressure. Recent Findings Although orexins (hypocretins) have been known for only 20 years, an impressive amount of data is now available regarding their physiological role. Hypothalamic orexin neurons are responsible for the control of food intake and energy expenditure, motivation, circadian rhythm of sleep and wake, memory, cognitive functions, and the cardiovascular system. Multiple studies show that orexinergic stimulation results in increased blood pressure and heart rate and that this effect may be efficiently attenuated by orexinergic antagonism. Increased activity of orexinergic neurons is also observed in animal models of hypertension. Summary Pharmacological intervention in the orexinergic system is now one of the therapeutic possibilities in insomnia. Although the role of orexin in the control of blood pressure is well described, we are still lacking clinical evidence that this is a possibility for a new approach in the treatment of cardiovascular diseases.
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Affiliation(s)
- Mariusz Sieminski
- Department of Emergency Medicine, Medical University of Gdansk, Smoluchowskiego 17, 80-235, Gdansk, Poland.
| | - Jacek Szypenbejl
- Department of Emergency Medicine, Medical University of Gdansk, Smoluchowskiego 17, 80-235, Gdansk, Poland
| | - Eemil Partinen
- Department of Neurology, University of Helsinki, Helsinki, Finland
- Vitalmed Helsinki Sleep Clinic, Helsinki, Finland
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14
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Dimatelis JJ, Mtintsilana A, Naidoo V, Stein DJ, Russell VA. Chronic light exposure alters serotonergic and orexinergic systems in the rat brain and reverses maternal separation-induced increase in orexin receptors in the prefrontal cortex. Metab Brain Dis 2018; 33:433-441. [PMID: 29039077 DOI: 10.1007/s11011-017-0123-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 10/04/2017] [Indexed: 12/22/2022]
Abstract
Maternal separation (MS) is a well-established rodent model of depression. Chronic constant light (CCL) treatment during adolescence has been shown to reverse the depression-like behaviour induced by MS. We aimed to further delineate the antidepressant effect of light by investigating the involvement of the dopaminergic, serotonergic and orexinergic systems. MS was used to induce changes in adult male Sprague-Dawley rats, some of whom were also treated with CCL for 3 weeks during adolescence. At P80, rats were decapitated and brain tissue collected for analysis of glutamate- and potassium-stimulated dopamine release in the nucleus accumbens (NAc) using an in vitro superfusion technique. Enzyme-linked immunosorbent assays were employed to measure 5-hydroxytryptamine (5-HT) levels in the hypothalamus and prefrontal cortex (PFC). Western blotting was used to measure orexin receptor 1 (OXR-1) and 2 (OXR-2) in the PFC. MS did not affect 5-HT levels in these rats. However, CCL increased hypothalamic 5-HT and reduced 5-HT levels in the PFC. CCL had opposite effects on OXR levels in the PFC of maternally separated and non-separated rats. MS increased OXR-1 and OXR-2 levels in the PFC, an effect that was normalized by CCL treatment. MS reduced glutamate-stimulated dopamine release in the NAc, an effect that was not reversed by CCL. The present results suggest that CCL treatment affects 5-HT and orexinergic systems in the MS model while not affecting the MS-induced decrease in dopamine release in the NAc. The reversal of changes in the orexinergic system may be of particular relevance to the antidepressant effect of CCL in depression.
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Affiliation(s)
- J J Dimatelis
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa.
| | - A Mtintsilana
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa
| | - V Naidoo
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa
| | - D J Stein
- Department of Psychiatry and Mental Health and MRC Unit on Anxiety & Stress Disorders, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa
| | - V A Russell
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa
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15
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Joshi A, Youssofzadeh V, Vemana V, McGinnity TM, Prasad G, Wong-Lin K. An integrated modelling framework for neural circuits with multiple neuromodulators. J R Soc Interface 2017; 14:rsif.2016.0902. [PMID: 28100828 PMCID: PMC5310738 DOI: 10.1098/rsif.2016.0902] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 12/16/2016] [Indexed: 12/04/2022] Open
Abstract
Neuromodulators are endogenous neurochemicals that regulate biophysical and biochemical processes, which control brain function and behaviour, and are often the targets of neuropharmacological drugs. Neuromodulator effects are generally complex partly owing to the involvement of broad innervation, co-release of neuromodulators, complex intra- and extrasynaptic mechanism, existence of multiple receptor subtypes and high interconnectivity within the brain. In this work, we propose an efficient yet sufficiently realistic computational neural modelling framework to study some of these complex behaviours. Specifically, we propose a novel dynamical neural circuit model that integrates the effective neuromodulator-induced currents based on various experimental data (e.g. electrophysiology, neuropharmacology and voltammetry). The model can incorporate multiple interacting brain regions, including neuromodulator sources, simulate efficiently and easily extendable to large-scale brain models, e.g. for neuroimaging purposes. As an example, we model a network of mutually interacting neural populations in the lateral hypothalamus, dorsal raphe nucleus and locus coeruleus, which are major sources of neuromodulator orexin/hypocretin, serotonin and norepinephrine/noradrenaline, respectively, and which play significant roles in regulating many physiological functions. We demonstrate that such a model can provide predictions of systemic drug effects of the popular antidepressants (e.g. reuptake inhibitors), neuromodulator antagonists or their combinations. Finally, we developed user-friendly graphical user interface software for model simulation and visualization for both fundamental sciences and pharmacological studies.
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Affiliation(s)
- Alok Joshi
- School of Computer Science, University of Manchester, Manchester, UK
| | - Vahab Youssofzadeh
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Vinith Vemana
- Computer Science and Engineering, Indian Institute of Technology (IIT) Jodhpur, Jodhpur, India
| | - T M McGinnity
- Intelligent Systems Research Centre (ISRC), University of Ulster, Derry-Londonderry, UK.,College of Science and Technology, Nottingham Trent University, Nottingham, UK
| | - Girijesh Prasad
- Intelligent Systems Research Centre (ISRC), University of Ulster, Derry-Londonderry, UK
| | - KongFatt Wong-Lin
- Intelligent Systems Research Centre (ISRC), University of Ulster, Derry-Londonderry, UK
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16
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Wong-Lin K, Wang DH, Moustafa AA, Cohen JY, Nakamura K. Toward a multiscale modeling framework for understanding serotonergic function. J Psychopharmacol 2017; 31:1121-1136. [PMID: 28417684 PMCID: PMC5606304 DOI: 10.1177/0269881117699612] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Despite its importance in regulating emotion and mental wellbeing, the complex structure and function of the serotonergic system present formidable challenges toward understanding its mechanisms. In this paper, we review studies investigating the interactions between serotonergic and related brain systems and their behavior at multiple scales, with a focus on biologically-based computational modeling. We first discuss serotonergic intracellular signaling and neuronal excitability, followed by neuronal circuit and systems levels. At each level of organization, we will discuss the experimental work accompanied by related computational modeling work. We then suggest that a multiscale modeling approach that integrates the various levels of neurobiological organization could potentially transform the way we understand the complex functions associated with serotonin.
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Affiliation(s)
- KongFatt Wong-Lin
- Intelligent Systems Research Centre, School of Computing and Intelligent Systems, University of Ulster, Magee Campus, Derry~Londonderry, UK
| | - Da-Hui Wang
- School of Systems Science, and National Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
| | - Ahmed A Moustafa
- School of Social Sciences and Psychology, and Marcs Institute for Brain and Behaviour, University of Western Sydney, Sydney, Australia
| | - Jeremiah Y Cohen
- Solomon H. Snyder Department of Neuroscience, Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Kae Nakamura
- Department of Physiology, Kansai Medical University, Hirakata, Osaka, Japan
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17
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Xu L, Wang H, Gong Y, Pang M, Sun X, Guo F, Gao S. Nesfatin-1 regulates the lateral hypothalamic area melanin-concentrating hormone-responsive gastric distension-sensitive neurons and gastric function via arcuate nucleus innervation. Metabolism 2017; 67:14-25. [PMID: 28081774 DOI: 10.1016/j.metabol.2016.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 10/18/2016] [Accepted: 10/23/2016] [Indexed: 12/15/2022]
Abstract
Nesfatin-1, a recently discovered neuropeptide involved in satiety. Recent studies have revealed that central nesfatin-1 inhibits gastric emptying and gastric acid secretion, though the mechanisms involved in these processes are not known. We aim to explore the effects of nesfatin-1 on a population of gastric distension (GD)-sensitive neurons in the lateral hypothalamus (LHA), gastric motility, and gastric secretion and the role for an arcuate nucleus (Arc)-LHA neural pathway in these processes. Single unit extracellular discharge recordings were made in of LHA. Further, gastric motility and gastric secretion in rats were monitored. Retrograde tracing and fluorescent immunohistochemical staining were used to explore nesfatin-1 neuron projection. The results revealed that administration of nesfatin-1 to the LHA or electric stimulation of the Arc could alter the neuronal activity of melanin-concentrating hormone (MCH)-responsive, GD-responsive neurons in LHA, which could be blocked by pretreatment with MCH receptor-1 antagonist PMC-3881-PI or weakened by pretreatment of a nesfatin-1 antibody in LHA. Administration of nesfatin-1 into LHA could inhibit gastric motility and gastric secretion, and these effects could be enhanced by administration of PMC-3881-PI. Electrical stimulation of Arc promoted the gastric motility and gastric secretion. Nesfatin-1 antibody or PMC-3881-PI pretreatment to LHA had no effect on Arc stimulation-induced gastric motility, but these pretreatments did alter Arc stimulation-induced effects on gastric secretion. Our findings suggest that nesfatin-1 signaling in LHA participates in the regulation of efferent information from the gastrointestinal tract and gastric secretion which also involve MCH signaling. Further, they show that a nesfatin-1-positive Arc to LHA pathway is critical for these effects.
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Affiliation(s)
- Luo Xu
- Department of Pathophysiology, Medical College of Qingdao University, Qingdao, Shandong, China.
| | - Hongbo Wang
- Department of Gastroenterology, Jimo People's Hospital, Qingdao, Shandong, China
| | - Yanling Gong
- Department of Pharmacy, College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, Shandong, China
| | - Mingjie Pang
- Department of Otolaryngology, Qingdao Municipal Hospital (Group), Qingdao, Shandong, China
| | - Xiangrong Sun
- Department of Pathophysiology, Medical College of Qingdao University, Qingdao, Shandong, China
| | - Feifei Guo
- Department of Pathophysiology, Medical College of Qingdao University, Qingdao, Shandong, China
| | - Shengli Gao
- Department of Pathophysiology, Medical College of Qingdao University, Qingdao, Shandong, China
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18
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McCue DL, Kasper JM, Hommel JD. Regulation of motivation for food by neuromedin U in the paraventricular nucleus and the dorsal raphe nucleus. Int J Obes (Lond) 2017; 41:120-128. [PMID: 27748746 PMCID: PMC5209284 DOI: 10.1038/ijo.2016.178] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 09/02/2016] [Accepted: 09/13/2016] [Indexed: 12/02/2022]
Abstract
BACKGROUND Motivation for high-fat food is thought to contribute to excess caloric intake in obese individuals. A novel regulator of motivation for food may be neuromedin U (NMU), a highly-conserved neuropeptide that influences food intake. Although these effects of NMU have primarily been attributed to signaling in the paraventricular nucleus of the hypothalamus (PVN), NMU has also been found in other brain regions involved in both feeding behavior and motivation. We investigate the effects of NMU on motivation for food and food intake, and identify the brain regions mediating these effects. METHODS The motivational state for a particular reinforcer (e.g., high-fat food) can be assessed using a progressive-ratio schedule of reinforcement under which an increasing number of lever presses are required to obtain subsequent reinforcers. Here, we have used a progressive-ratio operant responding paradigm in combination with an assessment of cumulative food intake to evaluate the effects of NMU administration in rats, and identify the brain regions mediating these effects. RESULTS We found that peripheral administration of NMU decreases operant responding for high-fat food in rats. Evaluation of Fos-like immunoreactivity in response to peripheral NMU indicated the PVN and dorsal raphe nucleus (DRN) as sites of action for NMU. NMU infusion into either region mimics the effects of peripheral NMU on food intake and operant responding for food. NMU-containing projections from the lateral hypothalamus (LH) to the PVN and DRN were identified as an endogenous source of NMU. CONCLUSIONS These results identify the DRN as a site of action for NMU, demonstrate that the LH provides endogenous NMU to the PVN and DRN and implicate NMU signaling in the PVN and DRN as a novel regulator of motivation for high-fat foods.
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Affiliation(s)
- David L. McCue
- Department of Neuroscience, University of Texas Medical Branch, Galveston, TX 77555-0615
- Center for Addiction Research, University of Texas Medical Branch, Galveston, TX 77555-0615
| | - James M. Kasper
- Center for Addiction Research, University of Texas Medical Branch, Galveston, TX 77555-0615
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555-0615
| | - Jonathan D. Hommel
- Center for Addiction Research, University of Texas Medical Branch, Galveston, TX 77555-0615
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555-0615
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19
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Cullen M, Wong-Lin K. Integrated dopaminergic neuronal model with reduced intracellular processes and inhibitory autoreceptors. IET Syst Biol 2016; 9:245-58. [PMID: 26577159 DOI: 10.1049/iet-syb.2015.0018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Dopamine (DA) is an important neurotransmitter for multiple brain functions, and dysfunctions of the dopaminergic system are implicated in neurological and neuropsychiatric disorders. Although the dopaminergic system has been studied at multiple levels, an integrated and efficient computational model that bridges from molecular to neuronal circuit level is still lacking. In this study, the authors aim to develop a realistic yet efficient computational model of a dopaminergic pre-synaptic terminal. They first systematically perturb the variables/substrates of an established computational model of DA synthesis, release and uptake, and based on their relative dynamical timescales and steady-state changes, approximate and reduce the model into two versions: one for simulating hourly timescale, and another for millisecond timescale. They show that the original and reduced models exhibit rather similar steady and perturbed states, whereas the reduced models are more computationally efficient and illuminate the underlying key mechanisms. They then incorporate the reduced fast model into a spiking neuronal model that can realistically simulate the spiking behaviour of dopaminergic neurons. In addition, they successfully include autoreceptor-mediated inhibitory current explicitly in the neuronal model. This integrated computational model provides the first step toward an efficient computational platform for realistic multiscale simulation of dopaminergic systems in in silico neuropharmacology.
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Affiliation(s)
- Maell Cullen
- Intelligent Systems Research Centre, University of Ulster, Magee Campus, Northland Road, L'Derry BT48 7JL, Northern Ireland, UK
| | - KongFatt Wong-Lin
- Intelligent Systems Research Centre, University of Ulster, Magee Campus, Northland Road, L'Derry BT48 7JL, Northern Ireland, UK.
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20
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Interacting Neural Processes of Feeding, Hyperactivity, Stress, Reward, and the Utility of the Activity-Based Anorexia Model of Anorexia Nervosa. Harv Rev Psychiatry 2016; 24:416-436. [PMID: 27824637 PMCID: PMC5485261 DOI: 10.1097/hrp.0000000000000111] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Anorexia nervosa (AN) is a psychiatric illness with minimal effective treatments and a very high rate of mortality. Understanding the neurobiological underpinnings of the disease is imperative for improving outcomes and can be aided by the study of animal models. The activity-based anorexia rodent model (ABA) is the current best parallel for the study of AN. This review describes the basic neurobiology of feeding and hyperactivity seen in both ABA and AN, and compiles the research on the role that stress-response and reward pathways play in modulating the homeostatic drive to eat and to expend energy, which become dysfunctional in ABA and AN.
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21
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Duan Y, Zhou S, Ma J, Yin P, Cao X. Forebrain NR2B overexpression enhancing fear acquisition and long-term potentiation in the lateral amygdala. Eur J Neurosci 2015; 42:2214-23. [PMID: 26118841 DOI: 10.1111/ejn.13008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 06/09/2015] [Accepted: 06/23/2015] [Indexed: 11/29/2022]
Abstract
N-methyl-d-aspartic acid (NMDA) receptor-dependent long-term potentiation (LTP) at the thalamus-lateral amygdala (T-LA) synapses is the basis for acquisition of auditory fear memory. However, the role of the NMDA receptor NR2B subunit in synaptic plasticity at T-LA synapses remains speculative. In the present study, using transgenic mice with forebrain-specific overexpression of the NR2B subunit, we have observed that forebrain NR2B overexpression results in enhanced LTP but does not alter long-term depression (LTD) at the T-LA synapses in transgenic mice. To elucidate the cellular mechanisms underlying enhanced LTP at T-LA synapses in these transgenic mice, AMPA and NMDA receptor-mediated postsynaptic currents have been measured. The data show a marked increasing in the amplitude and decay time of NMDA receptor-mediated currents in these transgenic mice. Consistent with enhanced LTP at T-LA synapses, NR2B-transgenic mice exhibit better performance in the acquisition of auditory fear memory than wild-type littermates. Our results demonstrate that up-regulation of NR2B expression facilitates acquisition of auditory cued fear memory and enhances LTP at T-LA synapses.
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Affiliation(s)
- Yanhong Duan
- Key Laboratory of Brain Functional Genomics, Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, School of Life Sciences, East China Normal University, 3663 N. Zhongshan Rd., Shanghai, 200062, China
| | - Siqi Zhou
- Key Laboratory of Brain Functional Genomics, Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, School of Life Sciences, East China Normal University, 3663 N. Zhongshan Rd., Shanghai, 200062, China
| | - Jing Ma
- Key Laboratory of Brain Functional Genomics, Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, School of Life Sciences, East China Normal University, 3663 N. Zhongshan Rd., Shanghai, 200062, China
| | - Pengcheng Yin
- Key Laboratory of Brain Functional Genomics, Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, School of Life Sciences, East China Normal University, 3663 N. Zhongshan Rd., Shanghai, 200062, China
| | - Xiaohua Cao
- Key Laboratory of Brain Functional Genomics, Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, School of Life Sciences, East China Normal University, 3663 N. Zhongshan Rd., Shanghai, 200062, China
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22
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Calabrò RS, Cacciola A, Bramanti P, Milardi D. Neural correlates of consciousness: what we know and what we have to learn! Neurol Sci 2015; 36:505-13. [PMID: 25588680 DOI: 10.1007/s10072-015-2072-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 01/09/2015] [Indexed: 12/11/2022]
Abstract
Consciousness is a multifaceted concept with two major components: awareness of environment and of self (i.e., the content of consciousness) and wakefulness (i.e., the level of consciousness). Medically speaking, consciousness is the state of the patient's awareness of self and environment and his responsiveness to external stimulation and inner need. A basic understanding of consciousness and its neural correlates is of major importance for all clinicians, especially those involved with patients suffering from altered states of consciousness. To this end, in this review it is shown that consciousness is dependent on the brainstem and thalamus for arousal; that basic cognition is supported by recurrent electrical activity between the cortex and the thalamus at gamma band frequencies; and that some kind of working memory must, at least fleetingly, be present for awareness to occur. New advances in neuroimaging studies are also presented in order to better understand and demonstrate the neurophysiological basis of consciousness. In particular, recent functional magnetic resonance imaging studies have offered the possibility to measure directly and non-invasively normal and severely brain damaged subjects' brain activity, whilst diffusion tensor imaging studies have allowed evaluating white matter integrity in normal subjects and patients with disorder of consciousness.
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Affiliation(s)
- Rocco Salvatore Calabrò
- IRCCS Centro Neurolesi "Bonino Pulejo", S.S. 113, Via Palermo, Contrada Casazza, 98124, Messina, Italy,
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23
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Jalewa J, Wong-Lin K, McGinnity TM, Prasad G, Hölscher C. Increased number of orexin/hypocretin neurons with high and prolonged external stress-induced depression. Behav Brain Res 2014; 272:196-204. [DOI: 10.1016/j.bbr.2014.05.030] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 05/13/2014] [Accepted: 05/16/2014] [Indexed: 01/14/2023]
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24
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Sakhi K, Wegner S, Belle MDC, Howarth M, Delagrange P, Brown TM, Piggins HD. Intrinsic and extrinsic cues regulate the daily profile of mouse lateral habenula neuronal activity. J Physiol 2014; 592:5025-45. [PMID: 25194046 DOI: 10.1113/jphysiol.2014.280065] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The epithalamic lateral habenula (LHb) is implicated as part of the mammalian brain's circadian system. Anatomical evidence suggests that the LHb receives extrinsic circadian timing cues from retinal ganglion cells and the master clock in the suprachiasmatic nuclei (SCN). Intriguingly, some LHb neurones contain the molecular circadian clock, but it is unclear if and how intrinsic and extrinsic circadian processes influence neuronal activity in the mouse LHb. Here, using an in vitro brain slice preparation isolating the LHb from the SCN, we show through whole-cell patch-clamp recordings that LHb neurones exhibit heterogeneity in their resting state, but the majority spontaneously fire action potentials (APs). Discharge rate of APs varied from low firing in the early day to higher firing later in the day and was absent in LHb brain slices prepared from Cry1(-/-)Cry2(-/-) mice that lack a functional molecular clock. Low amplitude circadian oscillations in the molecular circadian clock were also monitored in LHb brain slices, but were absent in Cry1(-/-)Cry2(-/-) LHb brain tissue. A putative neurochemical output signal of the SCN, prokineticin 2 (PK2), inhibited some LHb neurones by elevating the frequency of GABA release in the LHb. Using multi-electrode recordings in vivo, we found that LHb neurones sluggishly respond to retinal illumination, suggesting that they receive such information through polysynaptic processes. In summary, our results show for the first time that intrinsic circadian signals are important for regulating LHb neuronal state, while the SCN-derived signal PK2 is less influential. Moreover, we demonstrate that mouse LHb neurones have access to and can respond to visual input, but such signals are unlikely to be directly communicated to the LHb. Broadly, these findings raise the possibility that intrinsic circadian signals are likely to be influential in shaping LHb contributions to cognition and emotionality.
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Affiliation(s)
- Kanwal Sakhi
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Sven Wegner
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Mino D C Belle
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Michael Howarth
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Philippe Delagrange
- Unité de Recherches et Découvertes en Neurosciences, Institut de Recherches Servier, 78290, Croissy-sur-Seine, France
| | - Timothy M Brown
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Hugh D Piggins
- Faculty of Life Sciences, University of Manchester, Manchester, UK
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