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de Ávila C, Gugula A, Trenk A, Intorcia AJ, Suazo C, Nolz J, Plamondon J, Khatri D, Tallant L, Caron A, Blasiak A, Serrano GE, Beach TG, Gundlach AL, Mastroeni DF. Unveiling a novel memory center in human brain: neurochemical identification of the nucleus incertus, a key pontine locus implicated in stress and neuropathology. Biol Res 2024; 57:46. [PMID: 39014514 PMCID: PMC11253401 DOI: 10.1186/s40659-024-00523-z] [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: 10/13/2023] [Accepted: 06/07/2024] [Indexed: 07/18/2024] Open
Abstract
BACKGROUND The nucleus incertus (NI) was originally described by Streeter in 1903, as a midline region in the floor of the fourth ventricle of the human brain with an 'unknown' function. More than a century later, the neuroanatomy of the NI has been described in lower vertebrates, but not in humans. Therefore, we examined the neurochemical anatomy of the human NI using markers, including the neuropeptide, relaxin-3 (RLN3), and began to explore the distribution of the NI-related RLN3 innervation of the hippocampus. METHODS Histochemical staining of serial, coronal sections of control human postmortem pons was conducted to reveal the presence of the NI by detection of immunoreactivity (IR) for the neuronal markers, microtubule-associated protein-2 (MAP2), glutamic acid dehydrogenase (GAD)-65/67 and corticotrophin-releasing hormone receptor 1 (CRHR1), and RLN3, which is highly expressed in NI neurons in diverse species. RLN3 and vesicular GABA transporter 1 (vGAT1) mRNA were detected by fluorescent in situ hybridization. Pons sections containing the NI from an AD case were immunostained for phosphorylated-tau, to explore potential relevance to neurodegenerative diseases. Lastly, sections of the human hippocampus were stained to detect RLN3-IR and somatostatin (SST)-IR. RESULTS In the dorsal, anterior-medial region of the human pons, neurons containing RLN3- and MAP2-IR, and RLN3/vGAT1 mRNA-positive neurons were observed in an anatomical pattern consistent with that of the NI in other species. GAD65/67- and CRHR1-immunopositive neurons were also detected within this area. Furthermore, RLN3- and AT8-IR were co-localized within NI neurons of an AD subject. Lastly, RLN3-IR was detected in neurons within the CA1, CA2, CA3 and DG areas of the hippocampus, in the absence of RLN3 mRNA. In the DG, RLN3- and SST-IR were co-localized in a small population of neurons. CONCLUSIONS Aspects of the anatomy of the human NI are shared across species, including a population of stress-responsive, RLN3-expressing neurons and a RLN3 innervation of the hippocampus. Accumulation of phosphorylated-tau in the NI suggests its possible involvement in AD pathology. Further characterization of the neurochemistry of the human NI will increase our understanding of its functional role in health and disease.
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Affiliation(s)
- Camila de Ávila
- Arizona State University-Banner Neurodegenerative Disease Research Center, Tempe, AZ, USA.
| | - Anna Gugula
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Aleksandra Trenk
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Anthony J Intorcia
- Arizona Alzheimer's Consortium, Phoenix, AZ, USA
- Banner Sun Health Research Institute, Sun City, AZ, USA
| | - Crystal Suazo
- Arizona State University-Banner Neurodegenerative Disease Research Center, Tempe, AZ, USA
| | - Jennifer Nolz
- Arizona State University-Banner Neurodegenerative Disease Research Center, Tempe, AZ, USA
| | | | - Divyanshi Khatri
- Arizona State University-Banner Neurodegenerative Disease Research Center, Tempe, AZ, USA
| | - Lauren Tallant
- Department of Neuroscience, Mayo Clinic, Scottsdale, AZ, USA
| | - Alexandre Caron
- Quebec Heart and Lung Institute, Quebec City, QC, Canada
- Faculty of Pharmacy, Université Laval, Quebec City, QC, Canada
| | - Anna Blasiak
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Geidy E Serrano
- Arizona Alzheimer's Consortium, Phoenix, AZ, USA
- Banner Sun Health Research Institute, Sun City, AZ, USA
| | - Thomas G Beach
- Arizona Alzheimer's Consortium, Phoenix, AZ, USA
- Banner Sun Health Research Institute, Sun City, AZ, USA
| | - Andrew L Gundlach
- Florey Department of Neuroscience and Mental Health and Department of Anatomy and Physiology and The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Diego F Mastroeni
- Arizona State University-Banner Neurodegenerative Disease Research Center, Tempe, AZ, USA
- Arizona Alzheimer's Consortium, Phoenix, AZ, USA
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Gil-Miravet I, Núñez-Molina Á, Navarro-Sánchez M, Castillo-Gómez E, Ros-Bernal F, Gundlach AL, Olucha-Bordonau FE. Nucleus incertus projections to rat medial septum and entorhinal cortex: rare collateralization and septal-gating of temporal lobe theta rhythm activity. Brain Struct Funct 2023:10.1007/s00429-023-02650-x. [PMID: 37173580 DOI: 10.1007/s00429-023-02650-x] [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: 12/24/2022] [Accepted: 05/04/2023] [Indexed: 05/15/2023]
Abstract
Nucleus incertus (NI) neurons in the pontine tegmentum give rise to ascending forebrain projections and express the neuropeptide relaxin-3 (RLN3) which acts via the relaxin-family peptide 3 receptor (RXFP3). Activity in the hippocampus and entorhinal cortex can be driven from the medial septum (MS), and the NI projects to all these centers, where a prominent pattern of activity is theta rhythm, which is related to spatial memory processing. Therefore, we examined the degree of collateralization of NI projections to the MS and the medial temporal lobe (MTL), comprising medial and lateral entorhinal cortex (MEnt, LEnt) and dentate gyrus (DG), and the ability of the MS to drive entorhinal theta in the adult rat. We injected fluorogold and cholera toxin-B into the MS septum and either MEnt, LEnt or DG, to determine the percentage of retrogradely labeled neurons in the NI projecting to both or single targets, and the relative proportion of these neurons that were RLN3-positive ( +). The projection to the MS was threefold stronger than that to the MTL. Moreover, a majority of NI neurons projected independently to either MS or the MTL. However, RLN3 + neurons collateralize significantly more than RLN3-negative (-) neurons. In in vivo studies, electrical stimulation of the NI induced theta activity in the MS and the entorhinal cortex, which was impaired by intraseptal infusion of an RXFP3 antagonist, R3(BΔ23-27)R/I5, particularly at ~ 20 min post-injection. These findings suggest that the MS plays an important relay function in the NI-induced generation of theta within the entorhinal cortex.
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Grants
- POSDOC/2021/19 Universitat Jaume I
- PREDOC/2021/19 Universitat Jaume I
- UJI-A2017-17 Universitat Jaume I
- POSDOC/2021/19 Universitat Jaume I
- PID2019-107809RB-I00 Ministerio de Ciencia, Innovación y Universidades
- RTI2018-095698-B-I00 Ministerio de Ciencia, Innovación y Universidades
- RTI2018-095698-B-I00 Ministerio de Ciencia, Innovación y Universidades
- RTI2018-095698-B-I00 Ministerio de Ciencia, Innovación y Universidades
- 19I436 Fundación Alicia Koplowitz
- 19I436 Fundación Alicia Koplowitz
- 19I436 Fundación Alicia Koplowitz
- AICO/2021/246 Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital, Generalitat Valenciana
- AICO/2021/246 Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital, Generalitat Valenciana
- AICO/2021/246 Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital, Generalitat Valenciana
- 1067522 National Health and Medical Research Council
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Affiliation(s)
- Isis Gil-Miravet
- Departamento de Medicina, Facultad de Ciencias de la Salud, Universitat Jaume I, CIBERSAM-ISCIII, S/N 12071, Castellón de la Plana, Spain
| | - Ángel Núñez-Molina
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - Mónica Navarro-Sánchez
- Departamento de Medicina, Facultad de Ciencias de la Salud, Universitat Jaume I, CIBERSAM-ISCIII, S/N 12071, Castellón de la Plana, Spain
| | - Esther Castillo-Gómez
- Departamento de Medicina, Facultad de Ciencias de la Salud, Universitat Jaume I, CIBERSAM-ISCIII, S/N 12071, Castellón de la Plana, Spain
| | - Francisco Ros-Bernal
- Departamento de Medicina, Facultad de Ciencias de la Salud, Universitat Jaume I, CIBERSAM-ISCIII, S/N 12071, Castellón de la Plana, Spain
| | - Andrew L Gundlach
- The Florey Institute of Neuroscience and Mental Health, Florey Department of Neuroscience and Mental Health and Department of Anatomy and Physiology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Francisco E Olucha-Bordonau
- Departamento de Medicina, Facultad de Ciencias de la Salud, Universitat Jaume I, CIBERSAM-ISCIII, S/N 12071, Castellón de la Plana, Spain.
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Ros-Bernal F, Gil-Miravet I, Lucerón J, Navarro-Sánchez M, Castillo-Gómez E, Gundlach AL, Olucha-Bordonau FE. Postnatal development of the relaxin-3 innervation of the rat medial septum. Front Neurosci 2023; 17:1176587. [PMID: 37234259 PMCID: PMC10206071 DOI: 10.3389/fnins.2023.1176587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 04/17/2023] [Indexed: 05/27/2023] Open
Abstract
Introduction The septal area provides a rich innervation to the hippocampus regulating hippocampal excitability to different behavioral states and modulating theta rhythmogenesis. However, little is known about the neurodevelopmental consequences of its alterations during postnatal development. The activity of the septohippocampal system is driven and/or modulated by ascending inputs, including those arising from the nucleus incertus (NI), many of which contain the neuropeptide, relaxin-3 (RLN3). Methods We examined at the molecular and cellular level the ontogeny of RLN3 innervation of the septal area in postnatal rat brains. Results Up until P13-15 there were only scattered fibers in the septal area, but a dense plexus had appeared by P17 that was extended and consolidated throughout the septal complex by P20. There was a decrease in the level of colocalization of RLN3 and synaptophysin between P15 and P20 that was reversed between P20 and adulthood. Biotinylated 3-kD dextran amine injections into the septum, revealed retrograde labeling present in the brainstem at P10-P13, but a decrease in anterograde fibers in the NI between P10-20. Simultaneously, a differentiation process began during P10-17, resulting in fewer NI neurons double-labeled for serotonin and RLN3. Discussion The onset of the RLN3 innervation of the septum complex between P17-20 is correlated with the onset of hippocampal theta rhythm and several learning processes associated with hippocampal function. Together, these data highlight the relevance and need for further analysis of this stage for normal and pathological septohippocampal development.
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Affiliation(s)
- Francisco Ros-Bernal
- Unitat Predepartamental de Medicina, Facultad de Ciencias de la Slud, Universitat Jaume I, Castellón, Spain
| | - Isis Gil-Miravet
- Unitat Predepartamental de Medicina, Facultad de Ciencias de la Slud, Universitat Jaume I, Castellón, Spain
| | - Jorge Lucerón
- Unitat Predepartamental de Medicina, Facultad de Ciencias de la Slud, Universitat Jaume I, Castellón, Spain
| | - Mónica Navarro-Sánchez
- Unitat Predepartamental de Medicina, Facultad de Ciencias de la Slud, Universitat Jaume I, Castellón, Spain
| | - Esther Castillo-Gómez
- Unitat Predepartamental de Medicina, Facultad de Ciencias de la Slud, Universitat Jaume I, Castellón, Spain
- Centro de Investigación Biomédica en Red de Salud Mental, (CIBERSAM), Madrid, Spain
| | - Andrew L. Gundlach
- The Florey Institute of Neuroscience and Mental Health, Florey Department of Neuroscience and Mental Health and Department of Anatomy and Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Francisco E. Olucha-Bordonau
- Unitat Predepartamental de Medicina, Facultad de Ciencias de la Slud, Universitat Jaume I, Castellón, Spain
- Centro de Investigación Biomédica en Red de Salud Mental, (CIBERSAM), Madrid, Spain
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Takeuchi Y, Nagy AJ, Barcsai L, Li Q, Ohsawa M, Mizuseki K, Berényi A. The Medial Septum as a Potential Target for Treating Brain Disorders Associated With Oscillopathies. Front Neural Circuits 2021; 15:701080. [PMID: 34305537 PMCID: PMC8297467 DOI: 10.3389/fncir.2021.701080] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 06/14/2021] [Indexed: 12/14/2022] Open
Abstract
The medial septum (MS), as part of the basal forebrain, supports many physiological functions, from sensorimotor integration to cognition. With often reciprocal connections with a broad set of peers at all major divisions of the brain, the MS orchestrates oscillatory neuronal activities throughout the brain. These oscillations are critical in generating sensory and emotional salience, locomotion, maintaining mood, supporting innate anxiety, and governing learning and memory. Accumulating evidence points out that the physiological oscillations under septal influence are frequently disrupted or altered in pathological conditions. Therefore, the MS may be a potential target for treating neurological and psychiatric disorders with abnormal oscillations (oscillopathies) to restore healthy patterns or erase undesired ones. Recent studies have revealed that the patterned stimulation of the MS alleviates symptoms of epilepsy. We discuss here that stimulus timing is a critical determinant of treatment efficacy on multiple time scales. On-demand stimulation may dramatically reduce side effects by not interfering with normal physiological functions. A precise pattern-matched stimulation through adaptive timing governed by the ongoing oscillations is essential to effectively terminate pathological oscillations. The time-targeted strategy for the MS stimulation may provide an effective way of treating multiple disorders including Alzheimer's disease, anxiety/fear, schizophrenia, and depression, as well as pain.
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Affiliation(s)
- Yuichi Takeuchi
- Department of Physiology, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Anett J. Nagy
- MTA-SZTE ‘Momentum’ Oscillatory Neuronal Networks Research Group, Department of Physiology, University of Szeged, Szeged, Hungary
| | - Lívia Barcsai
- MTA-SZTE ‘Momentum’ Oscillatory Neuronal Networks Research Group, Department of Physiology, University of Szeged, Szeged, Hungary
| | - Qun Li
- MTA-SZTE ‘Momentum’ Oscillatory Neuronal Networks Research Group, Department of Physiology, University of Szeged, Szeged, Hungary
| | - Masahiro Ohsawa
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Kenji Mizuseki
- Department of Physiology, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Antal Berényi
- MTA-SZTE ‘Momentum’ Oscillatory Neuronal Networks Research Group, Department of Physiology, University of Szeged, Szeged, Hungary
- Neurocybernetics Excellence Center, University of Szeged, Szeged, Hungary
- HCEMM-USZ Magnetotherapeutics Research Group, University of Szeged, Szeged, Hungary
- Neuroscience Institute, New York University, New York, NY, United States
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5
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Gil-Miravet I, Mañas-Ojeda A, Ros-Bernal F, Castillo-Gómez E, Albert-Gascó H, Gundlach AL, Olucha-Bordonau FE. Involvement of the Nucleus Incertus and Relaxin-3/RXFP3 Signaling System in Explicit and Implicit Memory. Front Neuroanat 2021; 15:637922. [PMID: 33867946 PMCID: PMC8044989 DOI: 10.3389/fnana.2021.637922] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 02/26/2021] [Indexed: 12/18/2022] Open
Abstract
Telencephalic cognitive and emotional circuits/functions are strongly modulated by subcortical inputs. The main focus of past research on the nature of this modulation has been on the widespread monoamine projections to the telencephalon. However, the nucleus incertus (NI) of the pontine tegmentum provides a strong GABAergic and peptidergic innervation of the hippocampus, basal forebrain, amygdala, prefrontal cortex, and related regions; and represents a parallel source of ascending modulation of cognitive and emotional domains. NI GABAergic neurons express multiple peptides, including neuromedin-B, cholecystokinin, and relaxin-3, and receptors for stress and arousal transmitters, including corticotrophin-releasing factor and orexins/hypocretins. A functional relationship exists between NI neurons and their associated peptides, relaxin-3 and neuromedin-B, and hippocampal theta rhythm, which in turn, has a key role in the acquisition and extinction of declarative and emotional memories. Furthermore, RXFP3, the cognate receptor for relaxin-3, is a Gi/o protein-coupled receptor, and its activation inhibits the cellular accumulation of cAMP and induces phosphorylation of ERK, processes associated with memory formation in the hippocampus and amygdala. Therefore, this review summarizes the role of NI transmitter systems in relaying stress- and arousal-related signals to the higher neural circuits and processes associated with memory formation and retrieval.
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Affiliation(s)
- Isis Gil-Miravet
- Unitat Predepartamental de Medicina, Facultat de Ciències de la Salut, Universitat Jaume I, Castelló de la Plana, Spain
| | - Aroa Mañas-Ojeda
- Unitat Predepartamental de Medicina, Facultat de Ciències de la Salut, Universitat Jaume I, Castelló de la Plana, Spain
| | - Francisco Ros-Bernal
- Unitat Predepartamental de Medicina, Facultat de Ciències de la Salut, Universitat Jaume I, Castelló de la Plana, Spain
| | - Esther Castillo-Gómez
- Unitat Predepartamental de Medicina, Facultat de Ciències de la Salut, Universitat Jaume I, Castelló de la Plana, Spain.,Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Madrid, Spain
| | - Hector Albert-Gascó
- Department of Clinical Neurosciences, UK Dementia Research Institute, University of Cambridge, Cambridge, United Kingdom
| | - Andrew L Gundlach
- The Florey Institute for Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Francisco E Olucha-Bordonau
- Unitat Predepartamental de Medicina, Facultat de Ciències de la Salut, Universitat Jaume I, Castelló de la Plana, Spain.,Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Madrid, Spain
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Topographical Visualization of the Reciprocal Projection between the Medial Septum and the Hippocampus in the 5XFAD Mouse Model of Alzheimer's Disease. Int J Mol Sci 2019; 20:ijms20163992. [PMID: 31426329 PMCID: PMC6721212 DOI: 10.3390/ijms20163992] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/13/2019] [Accepted: 08/14/2019] [Indexed: 12/13/2022] Open
Abstract
It is widely known that the degeneration of neural circuits is prominent in the brains of Alzheimer’s disease (AD) patients. The reciprocal connectivity of the medial septum (MS) and hippocampus, which constitutes the septo-hippocampo-septal (SHS) loop, is known to be associated with learning and memory. Despite the importance of the reciprocal projections between the MS and hippocampus in AD, the alteration of bidirectional connectivity between two structures has not yet been investigated at the mesoscale level. In this study, we adopted AD animal model, five familial AD mutations (5XFAD) mice, and anterograde and retrograde tracers, BDA and DiI, respectively, to visualize the pathology-related changes in topographical connectivity of the SHS loop in the 5XFAD brain. By comparing 4.5-month-old and 14-month-old 5XFAD mice, we successfully identified key circuit components of the SHS loop altered in 5XFAD brains. Remarkably, the SHS loop began to degenerate in 4.5-month-old 5XFAD mice before the onset of neuronal loss. The impairment of connectivity between the MS and hippocampus was accelerated in 14-month-old 5XFAD mice. These results demonstrate, for the first time, topographical evidence for the degradation of the interconnection between the MS and hippocampus at the mesoscale level in a mouse model of AD. Our results provide structural and functional insights into the interconnectivity of the MS and hippocampus, which will inform the use and development of various therapeutic approaches that target neural circuits for the treatment of AD.
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7
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Bueno D, Lima LB, Souza R, Gonçalves L, Leite F, Souza S, Furigo IC, Donato J, Metzger M. Connections of the laterodorsal tegmental nucleus with the habenular‐interpeduncular‐raphe system. J Comp Neurol 2019; 527:3046-3072. [DOI: 10.1002/cne.24729] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 06/06/2019] [Accepted: 06/07/2019] [Indexed: 02/06/2023]
Affiliation(s)
- Debora Bueno
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo São Paulo Brazil
| | - Leandro B. Lima
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo São Paulo Brazil
| | - Rudieri Souza
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo São Paulo Brazil
| | - Luciano Gonçalves
- Department of Human AnatomyFederal University of the Triângulo Mineiro Uberaba Brazil
| | - Fernanda Leite
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo São Paulo Brazil
| | - Stefani Souza
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo São Paulo Brazil
| | - Isadora C. Furigo
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo São Paulo Brazil
| | - Jose Donato
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo São Paulo Brazil
| | - Martin Metzger
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo São Paulo Brazil
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Sabetghadam A, Grabowiecka-Nowak A, Kania A, Gugula A, Blasiak E, Blasiak T, Ma S, Gundlach AL, Blasiak A. Melanin-concentrating hormone and orexin systems in rat nucleus incertus: Dual innervation, bidirectional effects on neuron activity, and differential influences on arousal and feeding. Neuropharmacology 2018; 139:238-256. [DOI: 10.1016/j.neuropharm.2018.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 06/20/2018] [Accepted: 07/04/2018] [Indexed: 12/24/2022]
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9
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Olucha-Bordonau FE, Albert-Gascó H, Ros-Bernal F, Rytova V, Ong-Pålsson EKE, Ma S, Sánchez-Pérez AM, Gundlach AL. Modulation of forebrain function by nucleus incertus and relaxin-3/RXFP3 signaling. CNS Neurosci Ther 2018; 24:694-702. [PMID: 29722152 DOI: 10.1111/cns.12862] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 03/22/2018] [Accepted: 03/28/2018] [Indexed: 01/05/2023] Open
Abstract
The nucleus incertus (NI) in the pontine tegmentum sends ascending projections to the midbrain, hypothalamus, amygdala, basal forebrain, hippocampus, and prefrontal cortex, and has a postulated role in modulating several forebrain functions. A substantial population of GABAergic NI neurons expresses the neuropeptide, relaxin-3, which acts via the Gi/o -protein-coupled receptor, RXFP3, present throughout the forebrain target regions. Broad and specific manipulations of these systems by activation or inhibition of the NI or modulating RXFP3 signaling have revealed key insights into the likely influence of the NI/relaxin-3/RXFP3 system on modalities including arousal, feeding, stress responses, anxiety and addiction, and attention and memory. This range of actions corresponds to a likely impact of NI/(relaxin-3) projections on multiple integrated circuits, but makes it difficult to draw conclusions about a generalized function for this network. This review will focus on the key physiological process of oscillatory theta rhythm and the neural circuits that promote it during behavioral activation, highlighting the ability of NI and relaxin-3/RXFP3 signaling systems to modulate these circuits. A better understanding of these mechanisms may provide a way to therapeutically adjust malfunction of forebrain activity present in several pathological conditions.
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Affiliation(s)
| | - Héctor Albert-Gascó
- Department of Medicine, School of Health Sciences, Universitat Jaume I, Castellón de la Plana, Spain
| | - Francisco Ros-Bernal
- Department of Medicine, School of Health Sciences, Universitat Jaume I, Castellón de la Plana, Spain
| | - Valeria Rytova
- The Florey Institute of Neuroscience and Mental Health, Parkville, Vic., Australia
| | - Emma K E Ong-Pålsson
- The Florey Institute of Neuroscience and Mental Health, Parkville, Vic., Australia
| | - Sherie Ma
- The Florey Institute of Neuroscience and Mental Health, Parkville, Vic., Australia
| | - Ana M Sánchez-Pérez
- Department of Medicine, School of Health Sciences, Universitat Jaume I, Castellón de la Plana, Spain
| | - Andrew L Gundlach
- The Florey Institute of Neuroscience and Mental Health, Parkville, Vic., Australia
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10
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Albert-Gascó H, Ma S, Ros-Bernal F, Sánchez-Pérez AM, Gundlach AL, Olucha-Bordonau FE. GABAergic Neurons in the Rat Medial Septal Complex Express Relaxin-3 Receptor (RXFP3) mRNA. Front Neuroanat 2018; 11:133. [PMID: 29403361 PMCID: PMC5777284 DOI: 10.3389/fnana.2017.00133] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 12/18/2017] [Indexed: 11/13/2022] Open
Abstract
The medial septum (MS) complex modulates hippocampal function and related behaviors. Septohippocampal projections promote and control different forms of hippocampal synchronization. Specifically, GABAergic and cholinergic projections targeting the hippocampal formation from the MS provide bursting discharges to promote theta rhythm, or tonic activity to promote gamma oscillations. In turn, the MS is targeted by ascending projections from the hypothalamus and brainstem. One of these projections arises from the nucleus incertus in the pontine tegmentum, which contains GABA neurons that co-express the neuropeptide relaxin-3 (Rln3). Both stimulation of the nucleus incertus and septal infusion of Rln3 receptor agonist peptides promotes hippocampal theta rhythm. The Gi/o-protein-coupled receptor, relaxin-family peptide receptor 3 (RXFP3), is the cognate receptor for Rln3 and identification of the transmitter phenotype of neurons expressing RXFP3 in the septohippocampal system can provide further insights into the role of Rln3 transmission in the promotion of septohippocampal theta rhythm. Therefore, we used RNAscope multiplex in situ hybridization to characterize the septal neurons expressing Rxfp3 mRNA in the rat. Our results demonstrate that Rxfp3 mRNA is abundantly expressed in vesicular GABA transporter (vGAT) mRNA- and parvalbumin (PV) mRNA-positive GABA neurons in MS, whereas ChAT mRNA-positive acetylcholine neurons lack Rxfp3 mRNA. Approximately 75% of Rxfp3 mRNA-positive neurons expressed vGAT mRNA (and 22% were PV mRNA-positive), while the remaining 25% expressed Rxfp3 mRNA only, consistent with a potential glutamatergic phenotype. Similar proportions were observed in the posterior septum. The occurrence of RXFP3 in PV-positive GABAergic neurons gives support to a role for the Rln3-RXFP3 system in septohippocampal theta rhythm.
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Affiliation(s)
- Hector Albert-Gascó
- Unitat Predepartamental de Medicina, Facultat de Ciències de la Salut, Universitat Jaume I, Castellón, Spain.,The Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
| | - Sherie Ma
- The Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Francisco Ros-Bernal
- Unitat Predepartamental de Medicina, Facultat de Ciències de la Salut, Universitat Jaume I, Castellón, Spain
| | - Ana M Sánchez-Pérez
- Unitat Predepartamental de Medicina, Facultat de Ciències de la Salut, Universitat Jaume I, Castellón, Spain
| | - Andrew L Gundlach
- The Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Francisco E Olucha-Bordonau
- Unitat Predepartamental de Medicina, Facultat de Ciències de la Salut, Universitat Jaume I, Castellón, Spain
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11
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Banqueri M, Méndez M, Arias JL. Spatial memory-related brain activity in normally reared and different maternal separation models in rats. Physiol Behav 2017; 181:80-85. [DOI: 10.1016/j.physbeh.2017.09.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 09/04/2017] [Accepted: 09/07/2017] [Indexed: 01/31/2023]
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12
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Lima LB, Bueno D, Leite F, Souza S, Gonçalves L, Furigo IC, Donato J, Metzger M. Afferent and efferent connections of the interpeduncular nucleus with special reference to circuits involving the habenula and raphe nuclei. J Comp Neurol 2017; 525:2411-2442. [DOI: 10.1002/cne.24217] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 03/13/2017] [Accepted: 03/15/2017] [Indexed: 02/06/2023]
Affiliation(s)
- Leandro B. Lima
- Department of Physiology & Biophysics; Institute of Biomedical Sciences, University of São Paulo; São Paulo Brazil
| | - Debora Bueno
- Department of Physiology & Biophysics; Institute of Biomedical Sciences, University of São Paulo; São Paulo Brazil
| | - Fernanda Leite
- Department of Physiology & Biophysics; Institute of Biomedical Sciences, University of São Paulo; São Paulo Brazil
| | - Stefani Souza
- Department of Physiology & Biophysics; Institute of Biomedical Sciences, University of São Paulo; São Paulo Brazil
| | - Luciano Gonçalves
- Department of Physiology & Biophysics; Institute of Biomedical Sciences, University of São Paulo; São Paulo Brazil
| | - Isadora C. Furigo
- Department of Physiology & Biophysics; Institute of Biomedical Sciences, University of São Paulo; São Paulo Brazil
| | - Jose Donato
- Department of Physiology & Biophysics; Institute of Biomedical Sciences, University of São Paulo; São Paulo Brazil
| | - Martin Metzger
- Department of Physiology & Biophysics; Institute of Biomedical Sciences, University of São Paulo; São Paulo Brazil
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13
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Haidar M, Guèvremont G, Zhang C, Bathgate RAD, Timofeeva E, Smith CM, Gundlach AL. Relaxin-3 inputs target hippocampal interneurons and deletion of hilar relaxin-3 receptors in "floxed-RXFP3" mice impairs spatial memory. Hippocampus 2017; 27:529-546. [PMID: 28100033 DOI: 10.1002/hipo.22709] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 01/10/2017] [Accepted: 01/12/2017] [Indexed: 11/10/2022]
Abstract
Hippocampus is innervated by γ-aminobutyric acid (GABA) "projection" neurons of the nucleus incertus (NI), including a population expressing the neuropeptide, relaxin-3 (RLN3). In studies aimed at gaining an understanding of the role of RLN3 signaling in hippocampus via its Gi/o -protein-coupled receptor, RXFP3, we examined the distribution of RLN3-immunoreactive nerve fibres and RXFP3 mRNA-positive neurons in relation to hippocampal GABA neuron populations. RLN3-positive elements were detected in close-apposition with a substantial population of somatostatin (SST)- and GABA-immunoreactive neurons, and a smaller population of parvalbumin- and calretinin-immunoreactive neurons in different hippocampal areas, consistent with the relative distribution patterns of RXFP3 mRNA and these marker transcripts. In light of the functional importance of the dentate gyrus (DG) hilus in learning and memory, and our anatomical data, we examined the possible influence of RLN3/RXFP3 signaling in this region on spatial memory. Using viral-based Cre/LoxP recombination methods and adult mice with a floxed Rxfp3 gene, we deleted Rxfp3 from DG hilar neurons and assessed spatial memory performance and affective behaviors. Following infusions of an AAV(1/2) -Cre-IRES-eGFP vector, Cre expression was observed in DG hilar neurons, including SST-positive cells, and in situ hybridization histochemistry for RXFP3 mRNA confirmed receptor depletion relative to levels in floxed-RXFP3 mice infused with an AAV(1/2) -eGFP (control) vector. RXFP3 depletion within the DG hilus impaired spatial reference memory in an appetitive T-maze task reflected by a reduced percentage of correct choices and increased time to meet criteria, relative to control. In a continuous spontaneous alternation Y-maze task, RXFP3-depleted mice made fewer alternations in the first minute, suggesting impairment of spatial working memory. However, RXFP3-depleted and control mice displayed similar locomotor activity, anxiety-like behavior in light/dark box and elevated-plus maze tests, and learning and long-term memory retention in the Morris water maze. These data indicate endogenous RLN3/RXFP3 signaling can modulate hippocampal-dependent spatial reference and working memory via effects on SST interneurons, and further our knowledge of hippocampal cognitive processing. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- M Haidar
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia
| | - G Guèvremont
- Department of Psychiatry and Neurosciences, Faculty of Medicine, Laval University, Quebec, Canada
| | - C Zhang
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia
| | - R A D Bathgate
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia.,Department of Biochemistry and Molecular Biology, The University of Melbourne, Victoria, Australia
| | - E Timofeeva
- Department of Psychiatry and Neurosciences, Faculty of Medicine, Laval University, Quebec, Canada
| | - C M Smith
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia.,School of Medicine, Deakin University, Victoria, Australia
| | - A L Gundlach
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia.,Department of Anatomy and Neuroscience, The University of Melbourne, Victoria, Australia
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14
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Martínez-Bellver S, Cervera-Ferri A, Luque-García A, Martínez-Ricós J, Valverde-Navarro A, Bataller M, Guerrero J, Teruel-Marti V. Causal relationships between neurons of the nucleus incertus and the hippocampal theta activity in the rat. J Physiol 2017; 595:1775-1792. [PMID: 27880004 DOI: 10.1113/jp272841] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 11/12/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The nucleus incertus is a key node of the brainstem circuitry involved in hippocampal theta rhythmicity. Synchronisation exists between the nucleus incertus and hippocampal activities during theta periods. By the Granger causality analysis, we demonstrated a directional information flow between theta rhythmical neurons in the nucleus incertus and the hippocampus in theta-on states. The electrical stimulation of the nucleus incertus is also able to evoke a phase reset of the hippocampal theta wave. Our data suggest that the nucleus incertus is a key node of theta generation and the modulation network. ABSTRACT In recent years, a body of evidence has shown that the nucleus incertus (NI), in the dorsal tegmental pons, is a key node of the brainstem circuitry involved in hippocampal theta rhythmicity. Ascending reticular brainstem system activation evokes hippocampal theta rhythm with coupled neuronal activity in the NI. In a recent paper, we showed three populations of neurons in the NI with differential firing during hippocampal theta activation. The objective of this work was to better evaluate the causal relationship between the activity of NI neurons and the hippocampus during theta activation in order to further understand the role of the NI in the theta network. A Granger causality analysis was run to determine whether hippocampal theta activity with sensory-evoked theta depends on the neuronal activity of the NI, or vice versa. The analysis showed causal interdependence between the NI and the hippocampus during theta activity, whose directional flow depended on the different neuronal assemblies of the NI. Whereas type I and II NI neurons mainly acted as receptors of hippocampal information, type III neuronal activity was the predominant source of flow between the NI and the hippocampus in theta states. We further determined that the electrical activation of the NI was able to reset hippocampal waves with enhanced theta-band power, depending on the septal area. Collectively, these data suggest that hippocampal theta oscillations after sensory activation show dependence on NI neuron activity, which could play a key role in establishing optimal conditions for memory encoding.
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Affiliation(s)
- Sergio Martínez-Bellver
- Neuronal Circuits Laboratory, Department of Anatomy and Human Embryology, University of Valencia, Valencia, Spain
| | - Ana Cervera-Ferri
- Neuronal Circuits Laboratory, Department of Anatomy and Human Embryology, University of Valencia, Valencia, Spain
| | - Aina Luque-García
- Neuronal Circuits Laboratory, Department of Anatomy and Human Embryology, University of Valencia, Valencia, Spain
| | - Joana Martínez-Ricós
- Neuronal Circuits Laboratory, Department of Anatomy and Human Embryology, University of Valencia, Valencia, Spain
| | - Alfonso Valverde-Navarro
- Neuronal Circuits Laboratory, Department of Anatomy and Human Embryology, University of Valencia, Valencia, Spain
| | - Manuel Bataller
- Digital Signal Processing Group, Department of Electronics and Engineering, University of Valencia, Burjassot (Valencia), Spain
| | - Juan Guerrero
- Digital Signal Processing Group, Department of Electronics and Engineering, University of Valencia, Burjassot (Valencia), Spain
| | - Vicent Teruel-Marti
- Neuronal Circuits Laboratory, Department of Anatomy and Human Embryology, University of Valencia, Valencia, Spain
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15
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Ma S, Smith CM, Blasiak A, Gundlach AL. Distribution, physiology and pharmacology of relaxin-3/RXFP3 systems in brain. Br J Pharmacol 2016; 174:1034-1048. [PMID: 27774604 DOI: 10.1111/bph.13659] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 10/12/2016] [Accepted: 10/17/2016] [Indexed: 01/29/2023] Open
Abstract
Relaxin-3 is a member of a superfamily of structurally-related peptides that includes relaxin and insulin-like peptide hormones. Soon after the discovery of the relaxin-3 gene, relaxin-3 was identified as an abundant neuropeptide in brain with a distinctive topographical distribution within a small number of GABAergic neuron populations that is well conserved across species. Relaxin-3 is thought to exert its biological actions through a single class-A GPCR - relaxin-family peptide receptor 3 (RXFP3). Class-A comprises GPCRs for relaxin-3 and insulin-like peptide-5 and other peptides such as orexin and the monoamine transmitters. The RXFP3 receptor is selectively activated by relaxin-3, whereas insulin-like peptide-5 is the cognate ligand for the related RXFP4 receptor. Anatomical and pharmacological evidence obtained over the last decade supports a function of relaxin-3/RXFP3 systems in modulating responses to stress, anxiety-related and motivated behaviours, circadian rhythms, and learning and memory. Electrophysiological studies have identified the ability of RXFP3 agonists to directly hyperpolarise thalamic neurons in vitro, but there are no reports of direct cell signalling effects in vivo. This article provides an overview of earlier studies and highlights more recent research that implicates relaxin-3/RXFP3 neural network signalling in the integration of arousal, motivation, emotion and related cognition, and that has begun to identify the associated neural substrates and mechanisms. Future research directions to better elucidate the connectivity and function of different relaxin-3 neuron populations and their RXFP3-positive target neurons in major experimental species and humans are also identified. LINKED ARTICLES This article is part of a themed section on Recent Progress in the Understanding of Relaxin Family Peptides and their Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.10/issuetoc.
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Affiliation(s)
- Sherie Ma
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia
| | - Craig M Smith
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia.,School of Medicine, Deakin University, Geelong, Victoria, Australia
| | - Anna Blasiak
- Department of Neurophysiology and Chronobiology, Institute of Zoology, Jagiellonian University, Krakow, Poland
| | - Andrew L Gundlach
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia.,Department of Anatomy and Neuroscience, The University of Melbourne, Victoria, Australia
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16
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Ma S, Allocca G, Ong-Pålsson EKE, Singleton CE, Hawkes D, McDougall SJ, Williams SJ, Bathgate RAD, Gundlach AL. Nucleus incertus promotes cortical desynchronization and behavioral arousal. Brain Struct Funct 2016; 222:515-537. [PMID: 27206427 DOI: 10.1007/s00429-016-1230-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 04/26/2016] [Indexed: 01/09/2023]
Abstract
Arousal and vigilance are essential for survival and relevant regulatory neural circuits lie within the brainstem, hypothalamus and forebrain. The nucleus incertus (NI) is a distinct site within the pontine periventricular gray, containing a substantial population of GABAergic neurons with long-range, ascending projections. Existing neuroanatomical data and functional studies in anesthetized rats, suggest the NI is a central component of a midline behavioral control network well positioned to modulate arousal, vigilance and exploratory navigation, yet none of these roles have been established experimentally. We used a chemogenetic approach-clozapine-N-oxide (CNO) activation of virally delivered excitatory hM3Dq-DREADDs-to activate the NI in rats and examined the behavioral and physiological effects, relative to effects in naïve rats and appropriate viral-treated controls. hM3Dq activation by CNO resulted in long-lasting depolarization of NI neurons with action potentials, in vitro. Peripheral injection of CNO significantly increased c-Fos immunoreactivity in the NI and promoted cortical electroencephalograph (EEG) desynchronization. These brain changes were associated with heightened arousal, and increased locomotor activity in the homecage and in a novel environment. Furthermore, NI activation altered responses in a fear conditioning paradigm, reflected by increased head-scanning, vigilant behaviors during conditioned fear recall. These findings provide direct evidence that the NI promotes general arousal via a broad behavioral activation circuit and support early hypotheses, based on its connectivity, that the NI is a modulator of cognition and attention, and emotional and motivated behaviors.
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Affiliation(s)
- Sherie Ma
- The Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia. .,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia.
| | - Giancarlo Allocca
- The Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Emma K E Ong-Pålsson
- The Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Caitlin E Singleton
- The Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - David Hawkes
- The Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia.,Department of Pharmacology and Therapeutics, The University of Melbourne, Parkville, VIC, Australia
| | - Stuart J McDougall
- The Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Spencer J Williams
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Ross A D Bathgate
- The Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia.,Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Andrew L Gundlach
- The Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia. .,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia. .,Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia.
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17
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Central relaxin-3 receptor (RXFP3) activation increases ERK phosphorylation in septal cholinergic neurons and impairs spatial working memory. Brain Struct Funct 2016; 222:449-463. [PMID: 27146679 DOI: 10.1007/s00429-016-1227-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 04/12/2016] [Indexed: 01/09/2023]
Abstract
The medial septum/diagonal band (MS/DB) is a relay region connecting the hypothalamus and brainstem with the hippocampus, and both the MS/DB and dorsal/ventral hippocampus receive strong topographic GABA/peptidergic projections from the nucleus incertus of the pontine tegmentum. The neuropeptide relaxin-3, released by these neurons, is the cognate ligand for a Gi/o-protein-coupled receptor, RXFP3, which is highly expressed within the MS/DB, and both cholinergic and GABAergic neurons in this region of rat brain receive relaxin-3 positive terminals/boutons. Comprehensive in vitro studies have demonstrated that the cell signaling pathways altered by RXFP3 stimulation, include inhibition of forskolin-activated cAMP levels and activation of ERK phosphorylation. In this study we investigated whether intracerebroventricular (icv) injection of RXFP3-A2, a selective relaxin-3 receptor agonist, altered ERK phosphorylation levels in the MS/DB of adult male rats. We subsequently assessed the neurochemical phenotype of phosphorylated (p) ERK-positive neurons in MS/DB after icv RXFP3-A2 administration by dual-label immunostaining for pERK and neuronal markers for cholinergic and GABAergic neurons. Central RXFP3-A2 injection significantly increased levels of pERK immunoreactivity (IR) in MS/DB at 20 and 90 min post-injection, compared to vehicle and naive levels. In addition, RXFP3-A2 increased the number of cells expressing pERK-IR in the MS/DB at 90 (but not 20) min post-injection in cholinergic (but not GABAergic) neurons, which also expressed putative RXFP3-IR. Moreover, icv injection of RXFP3-A2 impaired alternation in a delayed spontaneous T-maze test of spatial working memory. The presence of RXFP3-like IR and the RXFP3-related activation of the MAPK/ERK pathway in MS/DB cholinergic neurons identifies them as a key target of ascending relaxin-3 projections with implications for the acute and chronic modulation of cholinergic neuron activity and function by relaxin-3/RXFP3 signaling.
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18
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Inactivation of nucleus incertus impairs passive avoidance learning and long term potentiation of the population spike in the perforant path-dentate gyrus evoked field potentials in rats. Neurobiol Learn Mem 2016; 130:185-93. [PMID: 26927304 DOI: 10.1016/j.nlm.2016.02.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 02/14/2016] [Accepted: 02/20/2016] [Indexed: 11/21/2022]
Abstract
Involvement of brainstem nucleus incertus (NI) in hippocampal theta rhythm suggests that this structure might play a role in hippocampal-dependent learning and memory. In the present study we aimed to address if NI is involved in an avoidance learning task as well as dentate gyrus (DG) short-term and long-term potentiation. Lidocaine was injected into the NI to transiently inactivate the nucleus, and control rats received saline. Role of NI was studied in passive avoidance learning (PAL) in 3 memory phases of acquisition, consolidation and retrieval. Levels of hippocampal phosphorylated p70 were also assessed in rats involved in PAL. Perforant path-DG short-term synaptic plasticity was studied upon NI inactivation before the paired-pulse stimulation, and also before or after tetanic stimulation in freely moving rats. It was found that NI inactivation delayed learning and impaired retention in the PAL task, with decreased levels of phosphorylated p70 in the respective groups. However, short-term plasticity was not affected by NI inactivation. But long term potentiation (LTP) of DG population spike was poorly induced with NI inactivation compared to the saline group, and it had no effect on population excitatory post-synaptic potential. Furthermore, when NI was inactivated after the induction of LTP, there was no difference between the saline and lidocaine groups. These observations suggest that NI has a role in PAL task, and its inactivation does not change the perforant path-DG granule cell synaptic input but decreases the excitability of the DG granule cells. Further studies should elucidate direct and indirect paths through which NI might influence hippocampal activity.
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19
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Brown RE, McKenna JT. Turning a Negative into a Positive: Ascending GABAergic Control of Cortical Activation and Arousal. Front Neurol 2015; 6:135. [PMID: 26124745 PMCID: PMC4463930 DOI: 10.3389/fneur.2015.00135] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 05/28/2015] [Indexed: 01/01/2023] Open
Abstract
Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the brain. Recent technological advances have illuminated the role of GABAergic neurons in control of cortical arousal and sleep. Sleep-promoting GABAergic neurons in the preoptic hypothalamus are well-known. Less well-appreciated are GABAergic projection neurons in the brainstem, midbrain, hypothalamus, and basal forebrain, which paradoxically promote arousal and fast electroencephalographic (EEG) rhythms. Thus, GABA is not purely a sleep-promoting neurotransmitter. GABAergic projection neurons in the brainstem nucleus incertus and ventral tegmental nucleus of Gudden promote theta (4-8 Hz) rhythms. Ventral tegmental area GABAergic neurons, neighboring midbrain dopamine neurons, project to the frontal cortex and nucleus accumbens. They discharge faster during cortical arousal and regulate reward. Thalamic reticular nucleus GABAergic neurons initiate sleep spindles in non-REM sleep. In addition, however, during wakefulness, they tonically regulate the activity of thalamocortical neurons. Other GABAergic inputs to the thalamus arising in the globus pallidus pars interna, substantia nigra pars reticulata, zona incerta, and basal forebrain regulate motor activity, arousal, attention, and sensory transmission. Several subpopulations of cortically projecting GABAergic neurons in the basal forebrain project to the thalamus and neocortex and preferentially promote cortical gamma-band (30-80 Hz) activity and wakefulness. Unlike sleep-active GABAergic neurons, these ascending GABAergic neurons are fast-firing neurons which disinhibit and synchronize the activity of their forebrain targets, promoting the fast EEG rhythms typical of conscious states. They are prominent targets of GABAergic hypnotic agents. Understanding the properties of ascending GABAergic neurons may lead to novel treatments for diseases involving disorders of cortical activation and wakefulness.
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Affiliation(s)
- Ritchie E Brown
- Laboratory of Neuroscience, Department of Psychiatry, VA Boston Healthcare System, Harvard Medical School , Brockton, MA , USA
| | - James T McKenna
- Laboratory of Neuroscience, Department of Psychiatry, VA Boston Healthcare System, Harvard Medical School , Brockton, MA , USA
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20
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Ma S, Gundlach AL. Ascending control of arousal and motivation: role of nucleus incertus and its peptide neuromodulators in behavioural responses to stress. J Neuroendocrinol 2015; 27:457-67. [PMID: 25612218 DOI: 10.1111/jne.12259] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 01/12/2015] [Accepted: 01/15/2015] [Indexed: 02/06/2023]
Abstract
Arousal is a process that involves the activation of ascending neural pathways originating in the rostral pons that project to the forebrain through the midbrain reticular formation to promote the activation of key cortical, thalamic, hypothalamic and limbic centres. Established modulators of arousal include the cholinergic, serotonergic, noradrenergic and dopaminergic networks originating in the pons and midbrain. Recent data indicate that a population of largely GABAergic projection neurones located in the nucleus incertus (NI) are also involved in arousal and motivational processes. The NI has prominent efferent connections with distinct hypothalamic, amygdalar and thalamic nuclei, in addition to dense projections to key brain regions associated with the generation and pacing of hippocampal activity. The NI receives strong inputs from the prefrontal cortex, lateral habenula and the interpeduncular and median raphe nuclei, suggesting it is highly integrated in circuits regulating higher cognitive behaviours (hippocampal theta rhythm) and emotion. Anatomical and functional studies have revealed that the NI is a rich source of multiple peptide neuromodulators, including relaxin-3, and may mediate extra-hypothalamic effects of the stress hormone corticotrophin-releasing factor, as well as other key modulators such as orexins and oxytocin. This review provides an overview of earlier studies and highlights more recent research that implicates this neural network in the integration of arousal and motivated behaviours and has begun to identify the associated mechanisms. Future research that should help to better clarify the connectivity and function of the NI in major experimental species and humans is also discussed.
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Affiliation(s)
- S Ma
- Neuropeptides Division, The Florey Institute of Neuroscience and Mental Health, Melbourne, VIC, Australia
- Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - A L Gundlach
- Neuropeptides Division, The Florey Institute of Neuroscience and Mental Health, Melbourne, VIC, Australia
- Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC, Australia
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21
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García-Avilés Á, Albert-Gascó H, Arnal-Vicente I, Elhajj E, Sanjuan-Arias J, Sanchez-Perez AM, Olucha-Bordonau F. Acute oral administration of low doses of methylphenidate targets calretinin neurons in the rat septal area. Front Neuroanat 2015; 9:33. [PMID: 25852493 PMCID: PMC4369875 DOI: 10.3389/fnana.2015.00033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 03/02/2015] [Indexed: 11/23/2022] Open
Abstract
Methylphenidate (MPD) is a commonly administered drug to treat children suffering from attention deficit hyperactivity disorder (ADHD). Alterations in septal driven hippocampal theta rhythm may underlie attention deficits observed in these patients. Amongst others, the septo-hippocampal connections have long been acknowledged to be important in preserving hippocampal function. Thus, we wanted to ascertain if MPD administration, which improves attention in patients, could affect septal areas connecting with hippocampus. We used low and orally administered MPD doses (1.3, 2.7 and 5 mg/Kg) to rats what mimics the dosage range in humans. In our model, we observed no effect when using 1.3 mg/Kg MPD; whereas 2.7 and 5 mg/Kg induced a significant increase in c-fos expression specifically in the medial septum (MS), an area intimately connected to the hippocampus. We analyzed dopaminergic areas such as nucleus accumbens and striatum, and found that only 5 mg/Kg induced c-fos levels increase. In these areas tyrosine hydroxylase correlated well with c-fos staining, whereas in the MS the sparse tyrosine hydroxylase fibers did not overlap with c-fos positive neurons. Double immunofluorescence of c-fos with neuronal markers in the septal area revealed that co-localization with choline acethyl transferase, parvalbumin, and calbindin with c-fos did not change with MPD treatment; whereas, calretinin and c-fos double labeled neurons increased after MPD administration. Altogether, these results suggest that low and acute doses of methylphenidate primary target specific populations of caltretinin medial septal neurons.
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Affiliation(s)
- Álvaro García-Avilés
- Departamento de Medicina, Facultad de Ciencias de la Salud, Universitat Jaume I Castellón, Spain
| | - Héctor Albert-Gascó
- Departamento de Medicina, Facultad de Ciencias de la Salud, Universitat Jaume I Castellón, Spain
| | - Isabel Arnal-Vicente
- CIBERSAM, INCLIVA, Unidad de Psiquiatría, Departamento Medicina, Facultad Medicina, Universitat de Valencia Valencia, Spain
| | - Ebtisam Elhajj
- Faculty of Science, University of Alexandria Alexandria, Egypt
| | - Julio Sanjuan-Arias
- CIBERSAM, INCLIVA, Unidad de Psiquiatría, Departamento Medicina, Facultad Medicina, Universitat de Valencia Valencia, Spain
| | - Ana María Sanchez-Perez
- Departamento de Medicina, Facultad de Ciencias de la Salud, Universitat Jaume I Castellón, Spain
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