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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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Median raphe serotonergic neurons projecting to the interpeduncular nucleus control preference and aversion. Nat Commun 2022; 13:7708. [PMID: 36550097 PMCID: PMC9780347 DOI: 10.1038/s41467-022-35346-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 11/30/2022] [Indexed: 12/24/2022] Open
Abstract
Appropriate processing of reward and aversive information is essential for survival. Although a critical role of serotonergic neurons in the dorsal raphe nucleus (DRN) in reward processing has been shown, the lack of rewarding effects with selective serotonin reuptake inhibitors (SSRIs) implies the presence of a discrete serotonergic system playing an opposite role to the DRN in the processing of reward and aversive stimuli. Here, we demonstrated that serotonergic neurons in the median raphe nucleus (MRN) of mice process reward and aversive information in opposite directions to DRN serotonergic neurons. We further identified MRN serotonergic neurons, including those projecting to the interpeduncular nucleus (5-HTMRN→IPN), as a key mediator of reward and aversive stimuli. Moreover, 5-HT receptors, including 5-HT2A receptors in the interpeduncular nucleus, are involved in the aversive properties of MRN serotonergic neural activity. Our findings revealed an essential function of MRN serotonergic neurons, including 5-HTMRN→IPN, in the processing of reward and aversive stimuli.
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Solórzano Hernández E, Cervantes Alfaro JM, Figueroa Rosales R, Gutiérrez Guzmán BÉ, López Vázquez MÁ, Olvera Cortés ME. Septal medial/diagonal band of Broca citalopram infusion reduces place learning efficiency and alters septohippocampal theta learning-related activity in rats. Behav Brain Res 2022; 435:114056. [PMID: 35963580 DOI: 10.1016/j.bbr.2022.114056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 11/26/2022]
Abstract
Increases in power and frequency of hippocampal theta activity have been related to efficient place learning and memory acquisition in hippocampal-dependent tests. The complex medial septum-diagonal band of Broca (MS/DBB) is the pacemaker of hippocampal theta activity, influenced by the ascending synchronizing system, and modulated by serotonergic raphe medial afferents, acting on cholinergic and GABAergic septal neurons. The suppression of hippocampal theta expression and the modulation of hippocampal learning and memory are attributed to serotonin. To simultaneously test these hypotheses, a daily local serotonin increase was induced by citalopram (CIT) infusion (100 µM, 0.88 µl, 0.2 µl/m) 15 min before training in the Morris water maze. The theta activity was recorded in the MS/DBB, dentate gyrus (DG) and CA1 of one group infused with artificial cerebrospinal liquid (ACL) and the other with CIT on Days 1-6 of training. After a probe trial (Day 7) and one resting day, the treatments were reversed (Days 8-11). The CIT MS/DBB infusion in the first 6 training days reduced the efficiency of spatial learning in association with reduced power in the DG, reduced MS/DBB-DG coherence, increased DG-CA1 coherence, and a lack of a negative correlation between MS/DBB power and swam distances. No effect of the CIT occurred once the information was acquired under ACL training. These results support a role of serotonin, in acting on the MS/DBB in the fine tuning of hippocampal learning and memory efficiency through the modulation of learning-related theta activity power and septohipocampal synchronization.
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Affiliation(s)
- Eduardo Solórzano Hernández
- Laboratorio de Neurociencias, División de Estudios de Posgrado, Facultad de Ciencias Médicas y Biológicas "Dr. Ignacio Chávez", Universidad Michoacana de San Nicolás de Hidalgo, Mexico; Laboratorio de Neurofisiología Experimental, División de Neurociencias, Centro de Investigación Biomédica de Michoacán, Instituto Mexicano del Seguro Social, Mexico.
| | - José Miguel Cervantes Alfaro
- Laboratorio de Neurociencias, División de Estudios de Posgrado, Facultad de Ciencias Médicas y Biológicas "Dr. Ignacio Chávez", Universidad Michoacana de San Nicolás de Hidalgo, Mexico.
| | - Rosalinda Figueroa Rosales
- Laboratorio de Neurofisiología Experimental, División de Neurociencias, Centro de Investigación Biomédica de Michoacán, Instituto Mexicano del Seguro Social, Mexico.
| | - Blanca Érika Gutiérrez Guzmán
- Laboratorio de Neurofisiología Experimental, División de Neurociencias, Centro de Investigación Biomédica de Michoacán, Instituto Mexicano del Seguro Social, Mexico.
| | - Miguel Ángel López Vázquez
- Laboratorio de Neuroplasticidad, División de Neurociencias, Centro de Investigación Biomédica de Michoacán, Instituto Mexicano del Seguro Social, Mexico.
| | - María Esther Olvera Cortés
- Laboratorio de Neurofisiología Experimental, División de Neurociencias, Centro de Investigación Biomédica de Michoacán, Instituto Mexicano del Seguro Social, Mexico.
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Stucynski JA, Schott AL, Baik J, Chung S, Weber F. Regulation of REM sleep by inhibitory neurons in the dorsomedial medulla. Curr Biol 2022; 32:37-50.e6. [PMID: 34735794 PMCID: PMC8752505 DOI: 10.1016/j.cub.2021.10.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 07/20/2021] [Accepted: 10/12/2021] [Indexed: 01/12/2023]
Abstract
The two major stages of mammalian sleep-rapid eye movement sleep (REMs) and non-REM sleep (NREMs)-are characterized by distinct brain rhythms ranging from millisecond to minute-long (infraslow) oscillations. The mechanisms controlling transitions between sleep stages and how they are synchronized with infraslow rhythms remain poorly understood. Using opto- and chemogenetic manipulation in mice, we show that GABAergic neurons in the dorsomedial medulla (dmM) promote the initiation and maintenance of REMs, in part through their projections to the dorsal and median raphe nuclei. Fiber photometry revealed that their activity is strongly increased during REMs and fluctuates during NREMs in close synchrony with infraslow oscillations in the sleep spindle band of the electroencephalogram. The phase of this rhythm influenced the latency and probability with which dmM activation induced REMs. Thus, dmM inhibitory neurons strongly promote REMs, and their slow activity fluctuations may coordinate the timing of REMs episodes with infraslow brain rhythms.
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Affiliation(s)
- Joseph A Stucynski
- Department of Neuroscience, Perelman School of Medicine, Chronobiology and Sleep Institute, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Amanda L Schott
- Department of Neuroscience, Perelman School of Medicine, Chronobiology and Sleep Institute, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Justin Baik
- Department of Neuroscience, Perelman School of Medicine, Chronobiology and Sleep Institute, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Shinjae Chung
- Department of Neuroscience, Perelman School of Medicine, Chronobiology and Sleep Institute, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Franz Weber
- Department of Neuroscience, Perelman School of Medicine, Chronobiology and Sleep Institute, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA.
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Cellular Effects of Rhynchophylline and Relevance to Sleep Regulation. Clocks Sleep 2021; 3:312-341. [PMID: 34207633 PMCID: PMC8293156 DOI: 10.3390/clockssleep3020020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/25/2021] [Accepted: 06/03/2021] [Indexed: 01/06/2023] Open
Abstract
Uncaria rhynchophylla is a plant highly used in the traditional Chinese and Japanese medicines. It has numerous health benefits, which are often attributed to its alkaloid components. Recent studies in humans show that drugs containing Uncaria ameliorate sleep quality and increase sleep time, both in physiological and pathological conditions. Rhynchophylline (Rhy) is one of the principal alkaloids in Uncaria species. Although treatment with Rhy alone has not been tested in humans, observations in rodents show that Rhy increases sleep time. However, the mechanisms by which Rhy could modulate sleep have not been comprehensively described. In this review, we are highlighting cellular pathways that are shown to be targeted by Rhy and which are also known for their implications in the regulation of wakefulness and sleep. We conclude that Rhy can impact sleep through mechanisms involving ion channels, N-methyl-d-aspartate (NMDA) receptors, tyrosine kinase receptors, extracellular signal-regulated kinases (ERK)/mitogen-activated protein kinases (MAPK), phosphoinositide 3-kinase (PI3K)/RAC serine/threonine-protein kinase (AKT), and nuclear factor-kappa B (NF-κB) pathways. In modulating multiple cellular responses, Rhy impacts neuronal communication in a way that could have substantial effects on sleep phenotypes. Thus, understanding the mechanisms of action of Rhy will have implications for sleep pharmacology.
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Hippocampal oscillatory dynamics and sleep atonia are altered in an animal model of fibromyalgia: Implications in the search for biomarkers. J Comp Neurol 2020; 528:1367-1391. [DOI: 10.1002/cne.24829] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 11/26/2019] [Accepted: 11/27/2019] [Indexed: 11/07/2022]
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Serotonin 5-HT 1A, 5-HT 2A and dopamine D 2 receptors strongly influence prefronto-hippocampal neural networks in alert mice: Contribution to the actions of risperidone. Neuropharmacology 2019; 158:107743. [PMID: 31430459 DOI: 10.1016/j.neuropharm.2019.107743] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 07/22/2019] [Accepted: 08/13/2019] [Indexed: 12/26/2022]
Abstract
Atypical antipsychotic drugs (APDs) used to treat positive and negative symptoms in schizophrenia block serotonin receptors 5-HT2AR and dopamine receptors D2R and stimulate 5-HT1AR directly or indirectly. However, the exact cellular mechanisms mediating their therapeutic actions remain unresolved. We recorded neural activity in the prefrontal cortex (PFC) and hippocampus (HPC) of freely-moving mice before and after acute administration of 5-HT1AR, 5-HT2AR and D2R selective agonists and antagonists and atypical APD risperidone. We then investigated the contribution of the three receptors to the actions of risperidone on brain activity via statistical modeling and pharmacological reversal (risperidone + 5-HT1AR antagonist WAY-100635, risperidone + 5-HT2A/2CR agonist DOI, risperidone + D2R agonist quinpirole). Risperidone, 5-HT1AR agonism with 8-OH-DPAT, 5-HT2AR antagonism with M100907, and D2R antagonism with haloperidol reduced locomotor activity of mice that correlated with a suppression of neural spiking, power of theta and gamma oscillations in PFC and HPC, and reduction of PFC-HPC theta phase synchronization. By contrast, activation of 5-HT2AR with DOI enhanced high-gamma oscillations in PFC and PFC-HPC high gamma functional connectivity, likely related to its hallucinogenic effects. Together, power changes, regression modeling and pharmacological reversals suggest an important role of 5-HT1AR agonism and 5-HT2AR antagonism in risperidone-induced alterations of delta, beta and gamma oscillations, while D2R antagonism may contribute to risperidone-mediated changes in delta oscillations. This study provides novel insight into the neural mechanisms for widely prescribed psychiatric medication targeting the serotonin and dopamine systems in two regions involved in the pathophysiology of schizophrenia.
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Korotkova T, Ponomarenko A, Monaghan CK, Poulter SL, Cacucci F, Wills T, Hasselmo ME, Lever C. Reconciling the different faces of hippocampal theta: The role of theta oscillations in cognitive, emotional and innate behaviors. Neurosci Biobehav Rev 2018; 85:65-80. [DOI: 10.1016/j.neubiorev.2017.09.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 08/22/2017] [Accepted: 09/02/2017] [Indexed: 12/30/2022]
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9
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Broms J, Grahm M, Haugegaard L, Blom T, Meletis K, Tingström A. Monosynaptic retrograde tracing of neurons expressing the G-protein coupled receptor Gpr151 in the mouse brain. J Comp Neurol 2017; 525:3227-3250. [PMID: 28657115 PMCID: PMC5601234 DOI: 10.1002/cne.24273] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 06/16/2017] [Accepted: 06/19/2017] [Indexed: 12/11/2022]
Abstract
GPR151 is a G‐protein coupled receptor for which the endogenous ligand remains unknown. In the nervous system of vertebrates, its expression is enriched in specific diencephalic structures, where the highest levels are observed in the habenular area. The habenula has been implicated in a range of different functions including behavioral flexibility, decision making, inhibitory control, and pain processing, which makes it a promising target for treating psychiatric and neurological disease. This study aimed to further characterize neurons expressing the Gpr151 gene, by tracing the afferent connectivity of this diencephalic cell population. Using pseudotyped rabies virus in a transgenic Gpr151‐Cre mouse line, monosynaptic afferents of habenular and thalamic Gpr151‐expressing neuronal populations could be visualized. The habenular and thalamic Gpr151 systems displayed both shared and distinct connectivity patterns. The habenular neurons primarily received input from basal forebrain structures, the bed nucleus of stria terminalis, the lateral preoptic area, the entopeduncular nucleus, and the lateral hypothalamic area. The Gpr151‐expressing neurons in the paraventricular nucleus of the thalamus was primarily contacted by medial hypothalamic areas as well as the zona incerta and projected to specific forebrain areas such as the prelimbic cortex and the accumbens nucleus. Gpr151 mRNA was also detected at low levels in the lateral posterior thalamic nucleus which received input from areas associated with visual processing, including the superior colliculus, zona incerta, and the visual and retrosplenial cortices. Knowledge about the connectivity of Gpr151‐expressing neurons will facilitate the interpretation of future functional studies of this receptor.
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Affiliation(s)
- Jonas Broms
- Psychiatric Neuromodulation Unit, Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden
| | - Matilda Grahm
- Psychiatric Neuromodulation Unit, Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden
| | - Lea Haugegaard
- Psychiatric Neuromodulation Unit, Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden
| | - Thomas Blom
- Biomedical Services Division, Faculty of Medicine, Lund University, Lund, Sweden
| | | | - Anders Tingström
- Psychiatric Neuromodulation Unit, Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden
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Gutiérrez-Guzmán BE, Hernández-Pérez JJ, Olvera-Cortés ME. Serotonergic modulation of septo-hippocampal and septo-mammillary theta activity during spatial learning, in the rat. Behav Brain Res 2017; 319:73-86. [DOI: 10.1016/j.bbr.2016.11.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/08/2016] [Accepted: 11/08/2016] [Indexed: 11/16/2022]
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Vertes RP, Hoover WB, Viana Di Prisco G. Theta Rhythm of the Hippocampus: Subcortical Control and Functional Significance. ACTA ACUST UNITED AC 2016; 3:173-200. [PMID: 15653814 DOI: 10.1177/1534582304273594] [Citation(s) in RCA: 160] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The theta rhythm is the largest extracellular synchronous signal that can be recorded from the mammalian brain and has been strongly implicated in mnemonic processes of the hippocampus. We describe (a) ascending brain stem–forebrain systems involved in controlling theta and nontheta (desynchronization) states of the hippocampal electroencephalogram; (b) theta rhythmically discharging cells in several structures of Papez's circuit and their possible functional significance, specifically with respect to head direction cells in this same circuit; and (c) the role of nucleus reuniens of the thalamus as a major interface between the medial prefrontal cortex and hippocampus and as a prominent source of afferent limbic information to the hippocampus. We suggest that the hippocampus receives two main types of input: theta rhythm from ascending brain stem– diencephaloseptal systems and information bearing mainly from thalamocortical/cortical systems. The temporal convergence of activity of these two systems results in the encoding of information in the hippocampus, primarily reaching it from the entorhinal cortex and nucleus reuniens.
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Kazmierska P, Konopacki J. Development of theta rhythm in hippocampal formation slices perfused with 5-HT1A antagonist, (S)WAY 100135. Brain Res 2015; 1625:142-50. [DOI: 10.1016/j.brainres.2015.08.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 07/28/2015] [Accepted: 08/28/2015] [Indexed: 12/01/2022]
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Hernández-Pérez JJ, Gutiérrez-Guzmán BE, López-Vázquez MÁ, Olvera-Cortés ME. Supramammillary serotonin reduction alters place learning and concomitant hippocampal, septal, and supramammillar theta activity in a Morris water maze. Front Pharmacol 2015; 6:250. [PMID: 26578960 PMCID: PMC4625187 DOI: 10.3389/fphar.2015.00250] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 10/14/2015] [Indexed: 11/29/2022] Open
Abstract
Hippocampal theta activity is related to spatial information processing, and high-frequency theta activity, in particular, has been linked to efficient spatial memory performance. Theta activity is regulated by the synchronizing ascending system (SAS), which includes mesencephalic and diencephalic relays. The supramamillary nucleus (SUMn) is located between the reticularis pontis oralis and the medial septum (MS), in close relation with the posterior hypothalamic nucleus (PHn), all of which are part of this ascending system. It has been proposed that the SUMn plays a role in the modulation of hippocampal theta-frequency; this could occur through direct connections between the SUMn and the hippocampus or through the influence of the SUMn on the MS. Serotonergic raphe neurons prominently innervate the hippocampus and several components of the SAS, including the SUMn. Serotonin desynchronizes hippocampal theta activity, and it has been proposed that serotonin may regulate learning through the modulation of hippocampal synchrony. In agreement with this hypothesis, serotonin depletion in the SUMn/PHn results in deficient spatial learning and alterations in CA1 theta activity-related learning in a Morris water maze. Because it has been reported that SUMn inactivation with lidocaine impairs the consolidation of reference memory, we asked whether changes in hippocampal theta activity related to learning would occur through serotonin depletion in the SUMn, together with deficiencies in memory. We infused 5,7-DHT bilaterally into the SUMn in rats and evaluated place learning in the standard Morris water maze task. Hippocampal (CA1 and dentate gyrus), septal and SUMn EEG were recorded during training of the test. The EEG power in each region and the coherence between the different regions were evaluated. Serotonin depletion in the SUMn induced deficient spatial learning and altered the expression of hippocampal high-frequency theta activity. These results provide evidence in support of a role for serotonin as a modulator of hippocampal learning, acting through changes in the synchronicity evoked in several relays of the SAS.
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Affiliation(s)
- J. Jesús Hernández-Pérez
- Laboratorio de Neurofisiología Experimental, División de Neurociencias, Centro de Investigación Biomédica de Michoacán, Instituto Mexicano del Seguro SocialMorelia, México
| | - Blanca E. Gutiérrez-Guzmán
- Laboratorio de Neurofisiología Experimental, División de Neurociencias, Centro de Investigación Biomédica de Michoacán, Instituto Mexicano del Seguro SocialMorelia, México
| | - Miguel Á. López-Vázquez
- Laboratorio de Neuroplasticidad de los Procesos Cognitivos, División de Neurociencias, Centro de Investigación Biomédica de Michoacán, Instituto Mexicano del Seguro SocialMorelia, México
- Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de HidalgoMorelia, México
| | - María E. Olvera-Cortés
- Laboratorio de Neurofisiología Experimental, División de Neurociencias, Centro de Investigación Biomédica de Michoacán, Instituto Mexicano del Seguro SocialMorelia, México
- *Correspondence: María E. Olvera-Cortés
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The hippocampus participates in the control of locomotion speed. Neuroscience 2015; 311:207-15. [PMID: 26597762 DOI: 10.1016/j.neuroscience.2015.10.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 09/30/2015] [Accepted: 10/20/2015] [Indexed: 12/25/2022]
Abstract
The hippocampus role in sensory-motor integration remains unclear. In these experiments we study its function in the locomotor control. To establish the connection between the hippocampus and the locomotor system, electrical stimulation in the CA1 region was applied and EMG recordings were obtained. We also evaluated the hindlimbs and forelimbs kinematic patterns in rats with a penetrating injury (PI) in the hippocampus as well as in a cortex-injured group (CI), which served as control. After the PI, tamoxifen a selective estrogen receptor modulator (SERM) that has been described as a neuroprotector and antiinflammatory drug, or vehicle was administered. Electrical stimulation in the hippocampus produces muscle contractions in the contralateral triceps, when 6 Hz or 8 Hz pulse trains were applied. The penetrating injury in the hippocampus reduced the EMG amplitude after the electrical stimulation. At 7 DPI (days post-injury) we observed an increase in the strides speed in all four limbs of the non-treated group, decreasing the correlation percentage of the studied joints. After 15 DPI the strides speed in the non-treated returned to normal. These changes did not occur in the tamoxifen group nor in cortex-injured group. After 30 days, the nontreated group presented a reduction in the number of pyramidal cell layer neurons at the injury site, in comparison to the tam-treated group. The loss of neurons, may cause the interruption of the trisynaptic circuit and changes in the locomotion speed. Tamoxifen preserves the pyramidal neurons after the injury, probably resulting in the strides speed recovery.
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Bland BH, Bland CE, MacIver MB. Median raphe stimulation-induced motor inhibition concurrent with suppression of type 1 and type 2 hippocampal theta. Hippocampus 2015; 26:289-300. [PMID: 26314691 DOI: 10.1002/hipo.22521] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 08/24/2015] [Accepted: 08/24/2015] [Indexed: 11/10/2022]
Abstract
This study investigated behavioral, anatomical and electrophysiological effects produced by electrical stimulation of posterior hypothalamic (PH) or median raphe (MR) nuclei, independently and during combined stimulation of both PH and MR. These three stimulation conditions were applied during spontaneous behavior in an open field and during PH stimulation-induced wheel running, while simultaneously recording hippocampal (HPC) field activity. An additional objective was to determine the effects of MR stimulation on Type 1 movement related theta and Type 2 sensory processing related theta. To achieve the latter, when behavioral studies were completed we studied the same rats under urethane anesthesia and then during urethane anesthesia with the addition of atropine sulfate (ATSO4). Here we demonstrated that electrical stimulation of a localized region of the MR nucleus resulted in a profound inhibition of both spontaneously occurring theta related motor behaviors and the theta related motor behaviors induced by electrical stimulation of the PH nucleus. Furthermore, this motor inhibition occurred concurrently with strong suppression of hippocampal theta field oscillations in the freely moving rat, a condition where the theta recorded is Type 2 sensory processing theta occurring coincidently with Type 1 movement related theta (Bland, 1986). Our results indicate that motor inhibition resulted from stimulation of neurons located in the mid central region of the MR, while stimulation in adjacent regions produced variable responses, including movements and theta activity. The present study provided evidence that the pharmacological basis of the suppression of Type 2 sensory processing HPC theta was cholinergic. However, MR inhibition of PH-induced wheel running was not affected by cholinergic blockade, which blocks Type 2 theta, indicating that MR stimulation-induced motor inhibition also requires the suppression of Type 1 theta.
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Affiliation(s)
- Brian H Bland
- Department of Psychology, Behavioral Neuroscience Research Group, the University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, Faculty of Medicine, the University of Calgary, Calgary, Alberta, Canada
| | - Cheryl E Bland
- Department of Psychology, Behavioral Neuroscience Research Group, the University of Calgary, Calgary, Alberta, Canada
| | - M Bruce MacIver
- Neuropharmacology Laboratory, Stanford School of Medicine, Stanford, California
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Orzeł-Gryglewska J, Matulewicz P, Jurkowlaniec E. Brainstem system of hippocampal theta induction: The role of the ventral tegmental area. Synapse 2015; 69:553-75. [PMID: 26234671 DOI: 10.1002/syn.21843] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 07/03/2015] [Accepted: 07/22/2015] [Indexed: 12/13/2022]
Abstract
This article summarizes the results of studies concerning the influence of the ventral tegmental area (VTA) on the hippocampal theta rhythm. Temporary VTA inactivation resulted in transient loss of the hippocampal theta. Permanent destruction of the VTA caused a long-lasting depression of the power of the theta and it also had some influence on the frequency of the rhythm. Activation of glutamate (GLU) receptors or decrease of GABAergic tonus in the VTA led to enhancement of dopamine release and increased hippocampal theta power. High time and frequency cross-correlation was detected for the theta band between the VTA and hippocampus during paradoxical sleep and active waking. Thus, the VTA may belong to the broad network involved in theta rhythm regulation. This article also presents a model of brainstem-VTA-hippocampal interactions in the induction of the hippocampal theta rhythm. The projections from the VTA which enhance theta rhythm are incorporated into the main theta generation pathway, in which the septum acts as the central node. The neuronal activity that may be responsible for the ability of the VTA to regulate theta probably derives from the structures associated with rapid eye movement (sleep) (REM) sleep or with sensorimotor activity (i.e., mainly from the pedunculopontine and laterodorsal tegmental nuclei and also from the raphe).
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Affiliation(s)
| | - Paweł Matulewicz
- Department of Animal and Human Physiology, University of Gdańsk, Gdańsk, 80-308, Poland
| | - Edyta Jurkowlaniec
- Department of Animal and Human Physiology, University of Gdańsk, Gdańsk, 80-308, Poland
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Puig MV, Gener T. Serotonin Modulation of Prefronto-Hippocampal Rhythms in Health and Disease. ACS Chem Neurosci 2015; 6:1017-25. [PMID: 25799292 DOI: 10.1021/cn500350e] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
There is mounting evidence that most cognitive functions depend upon the coordinated activity of neuronal networks often located far from each other in the brain. Ensembles of neurons synchronize their activity, generating oscillations at different frequencies that may encode behavior by allowing an efficient communication between brain areas. The serotonin system, by virtue of the widespread arborisation of serotonergic neurons, is in an excellent position to exert strong modulatory actions on brain rhythms. These include specific oscillatory activities in the prefrontal cortex and the hippocampus, two brain areas essential for many higher-order cognitive functions. Psychiatric patients show abnormal oscillatory activities in these areas, notably patients with schizophrenia who display psychotic symptoms as well as affective and cognitive impairments. Synchronization of neural activity between the prefrontal cortex and the hippocampus seems to be important for cognition and, in fact, reduced prefronto-hippocampal synchrony has been observed in a genetic mouse model of schizophrenia. Here, we review recent advances in the field of neuromodulation of brain rhythms by serotonin, focusing on the actions of serotonin in the prefrontal cortex and the hippocampus. Considering that the serotonergic system plays a crucial role in cognition and mood and is a target of many psychiatric treatments, it is surprising that this field of research is still in its infancy. In that regard, we point to future investigations that are much needed in this field.
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Affiliation(s)
- M. Victoria Puig
- Neuroscience Programme, Hospital del Mar Medical Research Institute (IMIM), Barcelona Biomedical Research Park (PRBB), Barcelona, Spain
| | - Thomas Gener
- Neuroscience Programme, Hospital del Mar Medical Research Institute (IMIM), Barcelona Biomedical Research Park (PRBB), Barcelona, Spain
- Systems Biology Program, Centre for Genomic Regulation (CRG), Barcelona Biomedical Research Park (PRBB), Barcelona, Spain
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18
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Mesopontine median raphe regulates hippocampal ripple oscillation and memory consolidation. Nat Neurosci 2015; 18:728-35. [PMID: 25867120 PMCID: PMC4414896 DOI: 10.1038/nn.3998] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 03/13/2015] [Indexed: 12/14/2022]
Abstract
Sharp-wave associated field-oscillations (~200 Hz) of the hippocampus, referred to as “ripples”, are believed to be important for consolidation of explicit memory. Little is known about how ripples are regulated by other brain regions. Here we show that the median raphe region (MnR) plays a key role in regulating hippocampal ripple activity and memory consolidation. We performed in vivo simultaneous recording in the MnR and hippocampus, and found that when a group of MnR neurons were active, ripples were absent. Consistently, optogenetic stimulation of MnR neurons suppressed ripple activity, while inhibition of these neurons increased ripple activity. Importantly, using a fear conditioning procedure, we provided evidence that photostimulation of MnR neurons interfered with memory consolidation. Our results demonstrate a critical role of the MnR in regulating ripples and memory consolidation.
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Anxious and nonanxious mice show similar hippocampal sensory evoked oscillations under urethane anesthesia: difference in the effect of buspirone. Neural Plast 2015; 2015:186323. [PMID: 25949829 PMCID: PMC4408632 DOI: 10.1155/2015/186323] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Revised: 03/17/2015] [Accepted: 03/17/2015] [Indexed: 11/18/2022] Open
Abstract
Hippocampal oscillations recorded under urethane anesthesia are proposed to be modulated by anxiolytics. All classes of clinically effective anxiolytics were reported to decrease the frequency of urethane theta; however, recent findings raise concerns about the direct correlation of anxiolysis and the frequency of hippocampal theta. Here, we took advantage of our two inbred mouse strains displaying extremes of anxiety (anxious (AX) and nonanxious (nAX)) to compare the properties of hippocampal activity and to test the effect of an anxiolytic drugs. No difference was observed in the peak frequency or in the peak power between AX and nAX strains. Buspirone (Bus) applied in 2.5 mg/kg decreased anxiety of AX but did not have any effect on nAX as was tested by elevated plus maze and open field. Interestingly, Bus treatment increased hippocampal oscillatory frequency in the AX but left it unaltered in nAX mice. Saline injection did not have any effect on the oscillation. Paired-pulse facilitation was enhanced by Bus in the nAX, but not in the AX strain. Collectively, these results do not support the hypothesis that hippocampal activity under urethane may serve as a marker for potential anxiolytic drugs. Moreover, we could not confirm the decrease of frequency after anxiolytic treatment.
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Pezzato FA, Can A, Hoshino K, Horta JDAC, Mijares MG, Gould TD. Effect of lithium on behavioral disinhibition induced by electrolytic lesion of the median raphe nucleus. Psychopharmacology (Berl) 2015; 232:1441-50. [PMID: 25345734 PMCID: PMC4388762 DOI: 10.1007/s00213-014-3775-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 10/13/2014] [Indexed: 11/28/2022]
Abstract
RATIONALE Alterations in brainstem circuits have been proposed as a possible mechanism underlying the etiology of mood disorders. Projections from the median raphe nucleus (MnR) modulate dopaminergic activity in the forebrain and are also part of a behavioral disinhibition/inhibition system that produces phenotypes resembling behavioral variations manifested during manic and depressive phases of bipolar disorder. OBJECTIVE The aim of this study is to assess the effect of chronic lithium treatment on behavioral disinhibition induced by MnR lesions. METHODS MnR electrolytic lesions were performed in C57BL/6J mice, with sham-operated and intact animals as control groups. Following recovery, mice were chronically treated with lithium (LiCl, added in chow) followed by behavioral testing. RESULTS MnR lesion induced manic-like behavioral alterations including hyperactivity in the open field (OF), stereotyped circling, anxiolytic/risk taking in the elevated plus maze (EPM) and light/dark box (LDB) tests, and increased basal body temperature. Lithium was specifically effective in reducing OF hyperactivity and stereotypy but did not reverse (EPM) or had a nonspecific effect (LDB) on anxiety/risk-taking measures. Additionally, lithium decreased saccharin preference and prevented weight loss during single housing. CONCLUSIONS Our data support electrolytic lesions of the MnR as an experimental model of a hyper-excitable/disinhibited phenotype consistent with some aspects of mania that are attenuated by the mood stabilizer lithium. Given lithium's relatively specific efficacy in treating mania, these data support the hypothesis that manic symptoms derive not only from the stimulation of excitatory systems but also from inactivation or decreased activity of inhibitory mechanisms.
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21
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Sánchez-Pérez AM, Arnal-Vicente I, Santos FN, Pereira CW, ElMlili N, Sanjuan J, Ma S, Gundlach AL, Olucha-Bordonau FE. Septal projections to nucleus incertus in the rat: bidirectional pathways for modulation of hippocampal function. J Comp Neurol 2014; 523:565-88. [PMID: 25269409 DOI: 10.1002/cne.23687] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 09/26/2014] [Accepted: 09/26/2014] [Indexed: 11/10/2022]
Abstract
Projections from the nucleus incertus (NI) to the septum have been implicated in the modulation of hippocampal theta rhythm. In this study we describe a previously uncharacterized projection from the septum to the NI, which may provide feedback modulation of the ascending circuitry. Fluorogold injections into the NI resulted in retrograde labeling in the septum that was concentrated in the horizontal diagonal band and areas of the posterior septum including the septofimbrial and triangular septal nuclei. Double-immunofluorescent staining indicated that the majority of NI-projecting septal neurons were calretinin-positive and some were parvalbumin-, calbindin-, or glutamic acid decarboxylase (GAD)-67-positive. Choline acetyltransferase-positive neurons were Fluorogold-negative. Injection of anterograde tracers into medial septum, or triangular septal and septofimbrial nuclei, revealed fibers descending to the supramammillary nucleus, median raphe, and the NI. These anterogradely labeled varicosities displayed synaptophysin immunoreactivity, indicating septal inputs form synapses on NI neurons. Anterograde tracer also colocalized with GAD-67-positive puncta in labeled fibers, which in some cases made close synaptic contact with GAD-67-labeled NI neurons. These data provide evidence for the existence of an inhibitory descending projection from medial and posterior septum to the NI that provides a "feedback loop" to modulate the comparatively more dense ascending NI projections to medial septum and hippocampus. Neural processes and associated behaviors activated or modulated by changes in hippocampal theta rhythm may depend on reciprocal connections between ascending and descending pathways rather than on unidirectional regulation via the medial septum.
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22
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McAllister-Williams RH, Alhaj HA, Massey A, Pankiv J, Reckermann U. Somatodendritic 5-hydroxytryptamine1A (5-HT1A) autoreceptor function in major depression as assessed using the shift in electroencephalographic frequency spectrum with buspirone. Psychol Med 2014; 44:767-777. [PMID: 23809646 DOI: 10.1017/s0033291713001475] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Positron emission tomography and post-mortem studies of the number of somatodendritic 5-hydroxytryptamine(1A) (5-HT(1A)) autoreceptors in raphé nuclei have found both increases and decreases in depression. However, recent genetic studies suggest they may be increased in number and/or function. The current study examined the effect of buspirone on the electroencephalographic (EEG) centroid frequency, a putative index of somatodendritic 5-HT(1A) receptor functional status, in a cohort of medication-free depressed patients and controls. METHOD A total of 15 depressed patients (nine male) and intelligence quotient (IQ)-, gender- and age-matched healthy controls had resting EEG recorded from 29 scalp electrodes prior to and 30, 60 and 90 min after oral buspirone (30 mg) administration. The effect of buspirone on somatodendritic 5-HT(1A) receptors was assessed by calculating the EEG centroid frequency between 6 and 10.5 Hz. The effect of buspirone on postsynaptic 5-HT(1A) receptors was assessed by measuring plasma growth hormone, prolactin and cortisol concentrations. RESULTS Analysis of variance revealed a significantly greater effect of buspirone on the EEG centroid frequency in patients compared with controls (F1,28 = 6.55, p = 0.016). There was no significant difference in the neuroendocrine responses between the two groups. CONCLUSIONS These findings are consistent with an increase in the functional status of somatodendritic, but not postsynaptic, 5-HT1A autoreceptors, in medication-free depressed patients in line with hypotheses based on genetic data. This increase in functional status would be hypothesized to lead to an increase in serotonergic negative feedback, and hence decreased release of 5-HT at raphé projection sites, in depressed patients.
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Affiliation(s)
| | - H A Alhaj
- Academic Clinical Psychiatry, University of Sheffield, UK
| | - A Massey
- Northumberland, Tyne and Wear NHS Foundation Trust, Newcastle upon Tyne, UK
| | - J Pankiv
- Northumberland, Tyne and Wear NHS Foundation Trust, Newcastle upon Tyne, UK
| | - U Reckermann
- Northumberland, Tyne and Wear NHS Foundation Trust, Newcastle upon Tyne, UK
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23
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Paul ED, Lowry CA. Functional topography of serotonergic systems supports the Deakin/Graeff hypothesis of anxiety and affective disorders. J Psychopharmacol 2013; 27:1090-106. [PMID: 23704363 DOI: 10.1177/0269881113490328] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Over 20 years ago, Deakin and Graeff hypothesized about the role of different serotonergic pathways in controlling the behavioral and physiologic responses to aversive stimuli, and how compromise of these pathways could lead to specific symptoms of anxiety and affective disorders. A growing body of evidence suggests these serotonergic pathways arise from topographically organized subpopulations of serotonergic neurons located in the dorsal and median raphe nuclei. We argue that serotonergic neurons in the dorsal/caudal parts of the dorsal raphe nucleus project to forebrain limbic regions involved in stress/conflict anxiety-related processes, which may be relevant for anxiety and affective disorders. Serotonergic neurons in the "lateral wings" of the dorsal raphe nucleus provide inhibitory control over structures controlling fight-or-flight responses. Dysfunction of this pathway could be relevant for panic disorder. Finally, serotonergic neurons in the median raphe nucleus, and the developmentally and functionally-related interfascicular part of the dorsal raphe nucleus, give rise to forebrain limbic projections that are involved in tolerance and coping with aversive stimuli, which could be important for affective disorders like depression. Elucidating the mechanisms through which stress activates these topographically and functionally distinct serotonergic pathways, and how dysfunction of these pathways leads to symptoms of neuropsychiatric disorders, may lead to the development of novel approaches to both the prevention and treatment of anxiety and affective disorders.
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Affiliation(s)
- Evan D Paul
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, Boulder, USA
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24
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Olvera-Cortés ME, Gutiérrez-Guzmán BE, López-Loeza E, Hernández-Pérez JJ, López-Vázquez MÁ. Serotonergic modulation of hippocampal theta activity in relation to hippocampal information processing. Exp Brain Res 2013; 230:407-26. [DOI: 10.1007/s00221-013-3679-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 08/07/2013] [Indexed: 10/26/2022]
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25
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The synchronous activity of lateral habenular neurons is essential for regulating hippocampal theta oscillation. J Neurosci 2013; 33:8909-21. [PMID: 23678132 DOI: 10.1523/jneurosci.4369-12.2013] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Lateral habenula (LHb) has attracted growing interest as a regulator of serotonergic and dopaminergic neurons in the CNS. However, it remains unclear how the LHb modulates brain states in animals. To identify the neural substrates that are under the influence of LHb regulation, we examined the effects of rat LHb lesions on the hippocampal oscillatory activity associated with the transition of brain states. Our results showed that the LHb lesion shortened the theta activity duration both in anesthetized and sleeping rats. Furthermore, this inhibitory effect of LHb lesion on theta maintenance depended upon an intact serotonergic median raphe, suggesting that LHb activity plays an essential role in maintaining hippocampal theta oscillation via the serotonergic raphe. Multiunit recording of sleeping rats further revealed that firing of LHb neurons showed significant phase-locking activity at each theta oscillation cycle in the hippocampus. LHb neurons showing activity that was coordinated with that of the hippocampal theta were localized in the medial LHb division, which receives afferents from the diagonal band of Broca (DBB), a pacemaker region for the hippocampal theta oscillation. Thus, our findings indicate that the DBB may pace not only the hippocampus, but also the LHb, during rapid eye movement sleep. Since serotonin is known to negatively regulate theta oscillation in the hippocampus, phase-locking activity of the LHb neurons may act, under the influence of the DBB, to maintain the hippocampal theta oscillation by modulating the activity of serotonergic neurons.
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26
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Ly S, Pishdari B, Lok LL, Hajos M, Kocsis B. Activation of 5-HT6 receptors modulates sleep-wake activity and hippocampal theta oscillation. ACS Chem Neurosci 2013; 4:191-9. [PMID: 23336058 DOI: 10.1021/cn300184t] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 12/10/2012] [Indexed: 01/20/2023] Open
Abstract
The modulatory role of 5-HT neurons and a number of different 5-HT receptor subtypes has been well documented in the regulation of sleep-wake cycles and hippocampal activity. A high level of 5-HT(6) receptor expression is present in the rat hippocampus. Further, hippocampal function has been shown to be modulated by both 5-HT(6) agonists and antagonists. In the current study, the potential involvement of 5-HT(6) receptors in the control of hippocampal theta rhythms and sleep-wake cycles has been investigated. Hippocampal activity was recorded by intracranial hippocampal electrodes both in anesthetized (n = 22) and in freely moving rats (n = 9). Theta rhythm was monitored in different sleep-wake states in freely moving rats and was elicited by stimulation of the brainstem reticular formation under anesthesia. Changes in theta frequency and power were analyzed before and after injection of the 5-HT(6) antagonist (SAM-531) and the 5-HT(6) agonist (EMD386088). In freely moving rats, EMD386088 suppressed sleep for several hours and significantly decreased theta peak frequency, while, in anesthetized rats, EMD386088 had no effect on theta power but significantly decreased theta frequency, which could be blocked by coadministration of SAM-531. SAM-531 alone did not change sleep-wake patterns and had no effect on theta parameters in both unanesthetized and anesthetized rats. Decreases in theta frequency induced by the 5-HT(6) receptor agonist correspond to previously described electrophysiological patterns shared by all anxiolytic drugs, and it is in line with its behavioral anxiolytic profile. The 5-HT(6) antagonist, however, failed to potentiate theta power, which is characteristic of many pro-cognitive substances, indicating that 5-HT(6) receptors might not tonically modulate hippocampal oscillations and sleep-wake patterns.
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Affiliation(s)
- Susanna Ly
- Department of Psychiatry, Beth Israel Deaconess
Medical Center, Harvard Medical School,
Boston, Massachusetts, United States
| | - Bano Pishdari
- Department of Psychiatry, Beth Israel Deaconess
Medical Center, Harvard Medical School,
Boston, Massachusetts, United States
| | - Ling Ling Lok
- Department of Psychiatry, Beth Israel Deaconess
Medical Center, Harvard Medical School,
Boston, Massachusetts, United States
| | - Mihaly Hajos
- Translational Neuropharmacology, Section of Comparative Medicine, Yale University School of Medicine, New Haven, Connecticut,
United States
| | - Bernat Kocsis
- Department of Psychiatry, Beth Israel Deaconess
Medical Center, Harvard Medical School,
Boston, Massachusetts, United States
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27
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Abstract
This review summarizes the brain mechanisms controlling sleep and wakefulness. Wakefulness promoting systems cause low-voltage, fast activity in the electroencephalogram (EEG). Multiple interacting neurotransmitter systems in the brain stem, hypothalamus, and basal forebrain converge onto common effector systems in the thalamus and cortex. Sleep results from the inhibition of wake-promoting systems by homeostatic sleep factors such as adenosine and nitric oxide and GABAergic neurons in the preoptic area of the hypothalamus, resulting in large-amplitude, slow EEG oscillations. Local, activity-dependent factors modulate the amplitude and frequency of cortical slow oscillations. Non-rapid-eye-movement (NREM) sleep results in conservation of brain energy and facilitates memory consolidation through the modulation of synaptic weights. Rapid-eye-movement (REM) sleep results from the interaction of brain stem cholinergic, aminergic, and GABAergic neurons which control the activity of glutamatergic reticular formation neurons leading to REM sleep phenomena such as muscle atonia, REMs, dreaming, and cortical activation. Strong activation of limbic regions during REM sleep suggests a role in regulation of emotion. Genetic studies suggest that brain mechanisms controlling waking and NREM sleep are strongly conserved throughout evolution, underscoring their enormous importance for brain function. Sleep disruption interferes with the normal restorative functions of NREM and REM sleep, resulting in disruptions of breathing and cardiovascular function, changes in emotional reactivity, and cognitive impairments in attention, memory, and decision making.
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Affiliation(s)
- Ritchie E Brown
- Laboratory of Neuroscience, VA Boston Healthcare System and Harvard Medical School, Brockton, Massachusetts 02301, USA
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28
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Crooks R, Jackson J, Bland BH. Dissociable pathways facilitate theta and non-theta states in the median raphe-Septohippocampal circuit. Hippocampus 2011; 22:1567-76. [DOI: 10.1002/hipo.20999] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/03/2011] [Indexed: 11/05/2022]
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29
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Alhaj H, Wisniewski G, McAllister-Williams RH. The use of the EEG in measuring therapeutic drug action: focus on depression and antidepressants. J Psychopharmacol 2011; 25:1175-91. [PMID: 21106608 DOI: 10.1177/0269881110388323] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A major issue in proof of concept studies and early clinical trials of novel therapeutic agents is that the active drugs can often have a relatively small additional effect compared with placebo. This is especially the case in psychiatry when we usually have no direct method of measuring the pathology underlying the disorder being studied but, rather, have to rely on the subjective assessment of psychiatric symptoms. The use of the electroencephalogram (EEG) offers two potential major means of addressing this problem. First it is able to provide direct data relating to neural activity that may be abnormal in certain disorders. As such there are opportunities for utilizing the EEG in a variety of ways as an objective outcome measure. Second there is growing evidence that in certain circumstances the EEG can be used to predict which patients are likely to respond to treatment, thus potentially increasing the power of studies by decreasing non-response rates and increasing mean changes in outcome measure. Both of these uses of the EEG are illustrated in reference to the study of mood disorders and in particular depression and its treatment with antidepressants.
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Affiliation(s)
- Hamid Alhaj
- Institute of Neuroscience, Newcastle University, Newcastle, UK
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30
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Narayanan V, Heiming RS, Jansen F, Lesting J, Sachser N, Pape HC, Seidenbecher T. Social defeat: impact on fear extinction and amygdala-prefrontal cortical theta synchrony in 5-HTT deficient mice. PLoS One 2011; 6:e22600. [PMID: 21818344 PMCID: PMC3144906 DOI: 10.1371/journal.pone.0022600] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 06/25/2011] [Indexed: 11/21/2022] Open
Abstract
Emotions, such as fear and anxiety, can be modulated by both environmental and genetic factors. One genetic factor is for example the genetically encoded variation of the serotonin transporter (5-HTT) expression. In this context, the 5-HTT plays a key role in the regulation of central 5-HT neurotransmission, which is critically involved in the physiological regulation of emotions including fear and anxiety. However, a systematic study which examines the combined influence of environmental and genetic factors on fear-related behavior and the underlying neurophysiological basis is missing. Therefore, in this study we used the 5-HTT-deficient mouse model for studying emotional dysregulation to evaluate consequences of genotype specific disruption of 5-HTT function and repeated social defeat for fear-related behaviors and corresponding neurophysiological activities in the lateral amygdala (LA) and infralimbic region of the medial prefrontal cortex (mPFC) in male 5-HTT wild-type (+/+), homo- (−/−) and heterozygous (+/−) mice. Naive males and experienced losers (generated in a resident-intruder paradigm) of all three genotypes, unilaterally equipped with recording electrodes in LA and mPFC, underwent a Pavlovian fear conditioning. Fear memory and extinction of conditioned fear was examined while recording neuronal activity simultaneously with fear-related behavior. Compared to naive 5-HTT+/+ and +/− mice, 5-HTT−/− mice showed impaired recall of extinction. In addition, 5-HTT−/− and +/− experienced losers showed delayed extinction learning and impaired recall of extinction. Impaired behavioral responses were accompanied by increased theta synchronization between the LA and mPFC during extinction learning in 5-HTT-/− and +/− losers. Furthermore, impaired extinction recall was accompanied with increased theta synchronization in 5-HTT−/− naive and in 5-HTT−/− and +/− loser mice. In conclusion, extinction learning and memory of conditioned fear can be modulated by both the 5-HTT gene activity and social experiences in adulthood, accompanied by corresponding alterations of the theta activity in the amygdala-prefrontal cortex network.
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Affiliation(s)
- Venu Narayanan
- Institute of Physiology I, Westfälische Wilhelms-University, Münster, Germany
| | - Rebecca S. Heiming
- Department of Behavioural Biology, Westfälische Wilhelms-University, Münster, Germany
- Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, Westfälische Wilhelms-University, Münster, Germany
| | - Friederike Jansen
- Department of Behavioural Biology, Westfälische Wilhelms-University, Münster, Germany
| | - Jörg Lesting
- Institute of Physiology I, Westfälische Wilhelms-University, Münster, Germany
| | - Norbert Sachser
- Department of Behavioural Biology, Westfälische Wilhelms-University, Münster, Germany
- Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, Westfälische Wilhelms-University, Münster, Germany
| | - Hans-Christian Pape
- Institute of Physiology I, Westfälische Wilhelms-University, Münster, Germany
| | - Thomas Seidenbecher
- Institute of Physiology I, Westfälische Wilhelms-University, Münster, Germany
- * E-mail:
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31
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Hale MW, Lowry CA. Functional topography of midbrain and pontine serotonergic systems: implications for synaptic regulation of serotonergic circuits. Psychopharmacology (Berl) 2011; 213:243-64. [PMID: 21088958 DOI: 10.1007/s00213-010-2089-z] [Citation(s) in RCA: 174] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Accepted: 10/29/2010] [Indexed: 12/20/2022]
Abstract
RATIONALE Dysfunction of serotonergic systems is thought to play an important role in a number of neurological and psychiatric disorders. Recent studies suggest that there is anatomical and functional diversity among serotonergic systems innervating forebrain systems involved in the control of physiologic and behavioral responses, including the control of emotional states. OBJECTIVE Here, we highlight the methods that have been used to investigate the heterogeneity of serotonergic systems and review the evidence for the unique anatomical, hodological, and functional properties of topographically organized subpopulations of serotonergic neurons in the midbrain and pontine raphe complex. CONCLUSION The emerging understanding of the topographically organized synaptic regulation of brainstem serotonergic systems, the topography of the efferent projections of these systems, and their functional properties, should enable identification of novel therapeutic approaches to treatment of neurological and psychiatric conditions that are associated with dysregulation of serotonergic systems.
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Affiliation(s)
- Matthew W Hale
- Department of Integrative Physiology, University of Colorado, Boulder, CO 80309-0354, USA
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32
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Sörman E, Wang D, Hajos M, Kocsis B. Control of hippocampal theta rhythm by serotonin: role of 5-HT2c receptors. Neuropharmacology 2011; 61:489-94. [PMID: 21281651 DOI: 10.1016/j.neuropharm.2011.01.029] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 12/24/2010] [Accepted: 01/17/2011] [Indexed: 10/18/2022]
Abstract
The hippocampus plays an important role in learning and memory and has been implicated in a number of diseases, including epilepsy, anxiety and schizophrenia. A prominent feature of the hippocampal network is the capability to generate rhythmic oscillations. Serotonergic modulation is known to play an important role in the regulation of theta rhythm. 5-HT2c receptors represent a specific target of psychopharmacology and, in particular, the behavioral effects of the 5-HT2c receptor agonist mCPP have been thoroughly tested. The present study used this compound and the selective 5-HT2c receptor antagonist SB-242084 to elucidate the role of 5-HT2c receptors in the generation of hippocampal oscillations. Hippocampal EEG was recorded and the power in the theta frequency range was monitored in different behaviors in freely-moving rats and after brainstem stimulation in anesthetized animals. We found that in freely-moving rats, mCPP suppressed hippocampal theta rhythm and the effect was stronger during REM sleep than during waking theta states. Under urethane anesthesia, mCPP decreased the power for both spontaneous and elicited theta rhythm in a dose-dependent manner and the 5-HT2c antagonist reversed this effect. The results of this study demonstrate that 5-HT2c receptors are important element of the serotonergic modulation of hippocampal theta oscillations and thus pharmacological interactions with these receptors can modulate physiological and pathological processes associated with limbic theta activity.
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Affiliation(s)
- Elin Sörman
- Department of Psychiatry, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215, USA
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Ikemoto S. Brain reward circuitry beyond the mesolimbic dopamine system: a neurobiological theory. Neurosci Biobehav Rev 2010; 35:129-50. [PMID: 20149820 PMCID: PMC2894302 DOI: 10.1016/j.neubiorev.2010.02.001] [Citation(s) in RCA: 298] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Revised: 01/31/2010] [Accepted: 02/03/2010] [Indexed: 12/22/2022]
Abstract
Reductionist attempts to dissect complex mechanisms into simpler elements are necessary, but not sufficient for understanding how biological properties like reward emerge out of neuronal activity. Recent studies on intracranial self-administration of neurochemicals (drugs) found that rats learn to self-administer various drugs into the mesolimbic dopamine structures-the posterior ventral tegmental area, medial shell nucleus accumbens and medial olfactory tubercle. In addition, studies found roles of non-dopaminergic mechanisms of the supramammillary, rostromedial tegmental and midbrain raphe nuclei in reward. To explain intracranial self-administration and related effects of various drug manipulations, I outlined a neurobiological theory claiming that there is an intrinsic central process that coordinates various selective functions (including perceptual, visceral, and reinforcement processes) into a global function of approach. Further, this coordinating process for approach arises from interactions between brain structures including those structures mentioned above and their closely linked regions: the medial prefrontal cortex, septal area, ventral pallidum, bed nucleus of stria terminalis, preoptic area, lateral hypothalamic areas, lateral habenula, periaqueductal gray, laterodorsal tegmental nucleus and parabrachical area.
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Affiliation(s)
- Satoshi Ikemoto
- Behavioral Neuroscience Research Branch, National Institute on Drug Abuse, National Institutes of Health, US Department of Health and Human Services, 251 Bayview Blvd, Suite 200, Baltimore, MD 21224, United States.
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Hippocampal theta rhythm after serotonergic activation of the pedunculopontine tegmental nucleus in anesthetized rats. Brain Res Bull 2010; 83:257-61. [DOI: 10.1016/j.brainresbull.2010.08.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 07/30/2010] [Accepted: 08/03/2010] [Indexed: 11/22/2022]
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Vertes RP. Serotonergic Regulation of Rhythmical Activity of the Brain, Concentrating on the Hippocampus. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2010. [DOI: 10.1016/s1569-7339(10)70084-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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The driving system for hippocampal theta in the brainstem: an examination by single neuron recording in urethane-anesthetized rats. Neurosci Lett 2009; 455:65-9. [PMID: 19429108 DOI: 10.1016/j.neulet.2009.03.028] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2009] [Revised: 03/09/2009] [Accepted: 03/11/2009] [Indexed: 11/22/2022]
Abstract
The brainstem has been shown to be involved in generating hippocampal theta; however, which brainstem region plays the most important role in generating the rhythm has remained unclear. To reveal which brainstem region triggers the theta, the hippocampal local field potential was recorded simultaneously with single unit activity in the brainstem of urethane-anesthetized rat. The firing latencies before theta onset and offset were compared among recording sites (deep mesencephalic nucleus, DpMe; pedunculopontine tegmental nucleus, PPT; nucleus pontis oralis, PnO). We examined the activities of 59 cells; PPT showed the highest proportion of neurons changing their firing rates at theta onset (14/16, 87.5%). The proportion in the PnO was 14/22 (63.6%), but the neurons in the PnO showed the earliest changes in latencies (0.57s before theta onset). The change in the PPT was 0.96s after theta onset. Regarding the theta offset, the PPT showed the highest proportion of neurons changing their firing rates at theta offset (9/16, 56.3%; the proportion in the PnO was 5/22, 22.7%), but the difference in latent time was not significant among recorded regions. The neurons in the DpMe did not show any remarkable firing tendency at theta onset and offset. From these results, we propose a driving system of hippocampal theta, in which neurons in the PnO first trigger the theta onset and then those in the PPT maintain the theta by activating broadly the brainstem areas for the wave.
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Jackson J, Bland BH, Antle MC. Nonserotonergic projection neurons in the midbrain raphe nuclei contain the vesicular glutamate transporter VGLUT3. Synapse 2009; 63:31-41. [PMID: 18925658 DOI: 10.1002/syn.20581] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The brainstem raphe nuclei are typically assigned a role in serotonergic brain function. However, numerous studies have reported that a large proportion of raphe projection cells are nonserotonergic. The identity of these projection cells is unknown. Recent studies have reported that the vesicular glutamate transporter VGLUT3 is found in both serotonergic and nonserotonergic neurons in both the median raphe (MR) and dorsal raphe (DR) nuclei. We injected the retrograde tracer cholera toxin subunit B into either the dorsal hippocampus or the medial septum (MS) and used triple labeled immunofluorescence to determine if nonserotonergic raphe cells projecting to these structures contained VGLUT3. Consistent with previous studies, only about half of retrogradely labeled MR neurons projecting to the hippocampus contained serotonin, whereas a majority of the retrogradely labeled nonserotonergic cells contained VGLUT3. Similar patterns were observed for MR cells projecting to the MS. About half of retrogradely labeled nonserotonergic neurons in the DR contained VGLUT3. Additionally, a large number of retrogradely labeled cells in the caudal linear and interpeduncular nuclei projecting to the MS were found to contain VGLUT3. These data suggest the enigmatic nonserotonergic projection from the MR to forebrain regions may be glutamatergic. In addition, these results demonstrate a dissociation between glutamatergic and serotonergic MR afferent inputs to the MS and hippocampus suggesting divergent and/or complementary roles of these pathways in modulating cellular activity within the septohippocampal network.
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Affiliation(s)
- Jesse Jackson
- Behavioral Neuroscience Research Group, Department of Psychology, University of Calgary, Calgary, Alberta, Canada
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Jackson J, Dickson CT, Bland BH. Median Raphe Stimulation Disrupts Hippocampal Theta Via Rapid Inhibition and State-Dependent Phase Reset of Theta-Related Neural Circuitry. J Neurophysiol 2008; 99:3009-26. [DOI: 10.1152/jn.00065.2008] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Evidence has accumulated suggesting that the median raphe (MR) mediates hippocampal theta desynchronization. However, few studies have evaluated theta-related neural circuitry during MR manipulation. In urethane-anesthetized rats, we investigated the effects of MR stimulation on hippocampal field and cell activity using high-frequency (100 Hz), theta burst (TBS), and slow-frequency electrical stimulation (0.5 Hz). We demonstrated that high-frequency stimulation of the MR did not elicit deactivated patterns in the forebrain, but rather elicited low-voltage activity in the neocortex and small-amplitude irregular activity (SIA) in the hippocampus. Both hippocampal phasic theta-on and -off cells were inhibited by high-frequency MR stimulation, although MR stimulation failed to affect cells that had neither state or phase relationships with theta field activity. TBS of the MR-induced theta field activity phase locked to the stimulation. Slow-frequency stimulation elicited a state-dependent reset of theta phase through a short-latency inhibition (5 ms) in phasic theta-on cells. Subpopulations of phasic theta-on cells responded in either oscillatory or nonoscillatory patterns to MR pulses, depending on their intraburst interval. off cells exhibited a state-dependent modulation of cell firing occurring preferentially during nontheta. The magnitude of MR-induced reset varied as a function of the phase of the theta oscillation when the pulse was administered. Therefore high-frequency stimulation of the MR appears to disrupt hippocampal theta through a state-dependent, short-latency inhibition of rhythmic cell populations in the hippocampus functioning to switch theta oscillations to an activated SIA field state.
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Ogren SO, Eriksson TM, Elvander-Tottie E, D'Addario C, Ekström JC, Svenningsson P, Meister B, Kehr J, Stiedl O. The role of 5-HT(1A) receptors in learning and memory. Behav Brain Res 2008; 195:54-77. [PMID: 18394726 DOI: 10.1016/j.bbr.2008.02.023] [Citation(s) in RCA: 233] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 02/13/2008] [Accepted: 02/13/2008] [Indexed: 12/12/2022]
Abstract
The ascending serotonin (5-HT) neurons innervate the cerebral cortex, hippocampus, septum and amygdala, all representing brain regions associated with various domains of cognition. The 5-HT innervation is diffuse and extensively arborized with few synaptic contacts, which indicates that 5-HT can affect a large number of neurons in a paracrine mode. Serotonin signaling is mediated by 14 receptor subtypes with different functional and transductional properties. The 5-HT(1A) subtype is of particular interest, since it is one of the main mediators of the action of 5-HT. Moreover, the 5-HT(1A) receptor regulates the activity of 5-HT neurons via autoreceptors, and it regulates the function of several neurotransmitter systems via postsynaptic receptors (heteroreceptors). This review assesses the pharmacological and genetic evidence that implicates the 5-HT(1A) receptor in learning and memory. The 5-HT(1A) receptors are in the position to influence the activity of glutamatergic, cholinergic and possibly GABAergic neurons in the cerebral cortex, hippocampus and in the septohippocampal projection, thereby affecting declarative and non-declarative memory functions. Moreover, the 5-HT(1A) receptor regulates several transduction mechanisms such as kinases and immediate early genes implicated in memory formation. Based on studies in rodents the stimulation of 5-HT(1A) receptors generally produces learning impairments by interfering with memory-encoding mechanisms. In contrast, antagonists of 5-HT(1A) receptors facilitate certain types of memory by enhancing hippocampal/cortical cholinergic and/or glutamatergic neurotransmission. Some data also support a potential role for the 5-HT(1A) receptor in memory consolidation. Available results also implicate the 5-HT(1A) receptor in the retrieval of aversive or emotional memories, supporting an involvement in reconsolidation. The contribution of 5-HT(1A) receptors in cognitive impairments in various psychiatric disorders is still unclear. However, there is evidence that 5-HT(1A) receptors may play differential roles in normal brain function and in psychopathological states. Taken together, the evidence indicates that the 5-HT(1A) receptor is a target for novel therapeutic advances in several neuropsychiatric disorders characterized by various cognitive deficits.
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Affiliation(s)
- Sven Ove Ogren
- Department of Neuroscience, Karolinska Institutet, SE-17177 Stockholm, Sweden.
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McAllister-Williams RH, Massey AE, Fairchild G. Repeated cortisol administration attenuates the EEG response to buspirone in healthy volunteers: evidence for desensitization of the 5-HT1A autoreceptor. J Psychopharmacol 2007; 21:826-32. [PMID: 17715208 DOI: 10.1177/0269881107078292] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
It has previously been postulated that the therapeutic effect of antidepressants, particularly selective serotonin re-uptake inhibitors (SSRIs), is mediated by a down-regulation of somatodendritic (presynaptic) 5-HT(1A) autoreceptors with chronic treatment. Animal studies have revealed that repeated administration of corticosteroids similarly down-regulate this receptor. However, it has previously been difficult to explore if this receptor is similarly modulated in man in vivo. The objective of this study was to explore the effect of repeated administration of cortisol to healthy volunteers utilising a novel putative index of somatodendritic 5-HT(1A) autoreceptor function. This method involves the administration of the 5-HT(1A) agonist buspirone and observing the subsequent negative shift in the frequency spectrum of the electroencephalogram (EEG). Healthy male volunteers were treated with cortisol 20 mg, or placebo, orally twice daily for 7 days in a double-blind random-order crossover study. After each treatment period volunteers were administered buspirone 30 mg orally prior to EEG recordings. Following a week's treatment with placebo, buspirone led to a negative shift in the EEG frequency spectrum as previously reported. However, following treatment with cortisol, the effect of buspirone was significantly attenuated. This is consistent with corticosteroids having a similar effect on somatodendritic 5-HT(1A) autoreceptors in man as seen in rodents.
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Affiliation(s)
- R Hamish McAllister-Williams
- Psychobiology Research Group, School of Neuroscience and Psychiatry, University of Newcastle, Newcastle upon Tyne, UK.
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41
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Vertes RP, Linley SB. Comparison of projections of the dorsal and median raphe nuclei, with some functional considerations. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.ics.2007.07.046] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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42
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McNaughton N, Kocsis B, Hajós M. Elicited hippocampal theta rhythm: a screen for anxiolytic and procognitive drugs through changes in hippocampal function? Behav Pharmacol 2007; 18:329-46. [PMID: 17762505 DOI: 10.1097/fbp.0b013e3282ee82e3] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Hippocampal damage produces cognitive deficits similar to dementia and changes in emotional and motivated reactions similar to anxiolytic drugs. The gross electrical activity of the hippocampus contains a marked 'theta rhythm'. This is a relatively high voltage sinusoidal waveform, resulting from synchronous phasic firing of cells, variation in which correlates with behavioural state. Like the hippocampus, theta has been linked to both cognitive and emotional functions. Critically, it has recently been shown that restoration of theta-like rhythmicity can restore lost cognitive function. We review the effects of systemic administration of drugs on hippocampal theta elicited by stimulation of the reticular formation. We conclude that reductions in the frequency of reticular-elicited theta provide what is currently the best in-vivo means of detecting antianxiety drugs. We also suggest that increases in the power of reticular-elicited theta could detect drugs useful in the treatment of disorders, such as dementia, that involve memory loss. We argue that these functionally distinct effects should be seen as indirect and that each results from a change in a single form of cognitive-emotional processing that particularly involves the hippocampus.
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Affiliation(s)
- Neil McNaughton
- Department of Psychology, University of Otago, Dunedin, New Zealand.
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Lemos JC, Pan YZ, Ma X, Lamy C, Akanwa AC, Beck SG. Selective 5-HT receptor inhibition of glutamatergic and GABAergic synaptic activity in the rat dorsal and median raphe. Eur J Neurosci 2007; 24:3415-30. [PMID: 17229091 PMCID: PMC2837807 DOI: 10.1111/j.1460-9568.2006.05222.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dorsal (DR) and median (MR) raphe nuclei contain 5-hydroxytryptamine (5-HT) cell bodies that give rise to the majority of the ascending 5-HT projections to the forebrain. The DR and MR have differential roles in mediating stress, anxiety and depression. Glutamate and GABA activity sculpt putative 5-HT neuronal firing and 5-HT release in a seemingly differential manner in the MR and DR, yet isolated glutamate and GABA activity within the DR and MR has not been systematically characterized. Visualized whole-cell voltage-clamp techniques were used to record excitatory and inhibitory postsynaptic currents (EPSC and IPSC) in 5-HT-containing neurons. There was a regional variation in action potential-dependent (spontaneous) and basal [miniature (m)] glutamate and GABAergic activity. mEPSC activity was greater than mIPSC activity in the DR, whereas in the MR the mIPSC activity was greater. These differences in EPSC and IPSC frequency indicate that glutamatergic and GABAergic input have distinct cytoarchitectures in the DR and MR. 5-HT(1B) receptor activation decreased mEPSC frequency in the DR and the MR, but selectively inhibited mIPSC activity only in the MR. This finding, in concert with its previously described function as an autoreceptor, suggests that 5-HT(1B) receptors influence the ascending 5-HT system through multiple mechanisms. The disparity in organization and integration of glutamatergic and GABAergic input to DR and MR neurons and their regulation by 5-HT(1B) receptors may contribute to the distinction in MR and DR regulation of forebrain regions and their differential function in the aetiology and pharmacological treatment of psychiatric disease states.
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Affiliation(s)
- Julia C. Lemos
- Department of Anaesthesiology, Children’s Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yu-Zhen Pan
- Department of Pediatrics, 4 North ARC, room 402 A, Children’s Hospital of Philadelphia and University of Pennsylvania, 3615 Civic Center Boulevard, Philadelphia, PA 19104–4318, USA
| | - Xiaohong Ma
- Department of Pediatrics, 4 North ARC, room 402 A, Children’s Hospital of Philadelphia and University of Pennsylvania, 3615 Civic Center Boulevard, Philadelphia, PA 19104–4318, USA
| | - Christophe Lamy
- Department of Pediatrics, 4 North ARC, room 402 A, Children’s Hospital of Philadelphia and University of Pennsylvania, 3615 Civic Center Boulevard, Philadelphia, PA 19104–4318, USA
| | - Adaure C. Akanwa
- Department of Pediatrics, 4 North ARC, room 402 A, Children’s Hospital of Philadelphia and University of Pennsylvania, 3615 Civic Center Boulevard, Philadelphia, PA 19104–4318, USA
| | - Sheryl G. Beck
- Department of Pediatrics, 4 North ARC, room 402 A, Children’s Hospital of Philadelphia and University of Pennsylvania, 3615 Civic Center Boulevard, Philadelphia, PA 19104–4318, USA
- Department of Anaesthesiology, Children’s Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA 19104, USA
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44
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Cohen H. Anxiolytic effect and memory improvement in rats by antisense oligodeoxynucleotide to 5-hydroxytryptamine-2A precursor protein. Depress Anxiety 2006; 22:84-93. [PMID: 16149040 DOI: 10.1002/da.20087] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Serotonergic (5-hydroxytryptamine; 5-HT) mechanisms have been implicated in a number of physiological and pathophysiological processes including mood, anxiety, and cognitive functioning. Among the many 5-HT receptor subtypes, the 5-HT2A receptors (5-HT2A-R) seem to be of particular importance in mediating these effects, and they are prime targets for a variety of psychoactive substances-from hallucinogenic drugs, through atypical antipsychotics, to anxiolytics and antidepressants. Various selective 5-HT2A-R ligands induce different behavioral responses. To determine whether receptor downregulation is an essential part of anxiolytic action, levels of 5-HT2A receptors were manipulated in rats using a nonpharmacological approach-by the administration of an antisense oligodeoxynucleotide (ASODN) to 5-HT2A-R. Each ASODN was injected icv between two and five times at 24-hr intervals. Control rats received injections of either a scrambled oligodeoxynucleotide (ScrODN) or the vehicle only. On Day 6, anxiety-related behavior was assessed in the elevated plus maze paradigm and performance of memory tasks in the Morris water maze. Gene transcripts were measured by quantitative reverse transcription polymerase chain reaction (PCR). The results show that compared to vehicle and ScrODN control animals, icv 5-HT2A-R-ASODN administrations for 4 consecutive days (but not less) significantly decreased anxietylike behavior and improved memory retention performance. The reduction in anxiety-related behavior in 5-HT2A-R-ASODN rats was accompanied by a decrease in 5-HT2A-R-mRNA expression in the frontal cortex and in the hippocampus. Receptor downregulation has been proposed as one of the central mechanisms for anxiolytic drug actions. Antisense-mediated downmanipulation of receptors in this study, especially of 5-HT2A, supports this theory.
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MESH Headings
- Animals
- Anti-Anxiety Agents/administration & dosage
- Anxiety/genetics
- Behavior, Animal/drug effects
- Cerebral Cortex/drug effects
- Down-Regulation
- Injections, Intraventricular
- Israel
- Male
- Maze Learning/drug effects
- Oligodeoxyribonucleotides, Antisense/administration & dosage
- Oligodeoxyribonucleotides, Antisense/genetics
- Protein Precursors/antagonists & inhibitors
- Protein Precursors/genetics
- RNA, Messenger/genetics
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT2A/biosynthesis
- Receptor, Serotonin, 5-HT2A/genetics
- Serotonin 5-HT2 Receptor Antagonists
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Affiliation(s)
- Hagit Cohen
- Ben-Gurion University of the Negev, Beer-Sheva, Israel.
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Gordon JA, Lacefield CO, Kentros CG, Hen R. State-dependent alterations in hippocampal oscillations in serotonin 1A receptor-deficient mice. J Neurosci 2006; 25:6509-19. [PMID: 16014712 PMCID: PMC6725436 DOI: 10.1523/jneurosci.1211-05.2005] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mice lacking the serotonin 1A receptor (5-HT(1A)R) show increased levels of anxiety-related behavior across multiple tests and background strains. Tissue-specific rescue experiments, lesion studies, and neurophysiological findings all point toward the hippocampus as a potential mediator of the phenotype. Serotonin, acting through 5-HT(1A)Rs, can suppress hippocampal theta-frequency oscillations, suggesting that theta oscillations might be increased in the knock-outs. To test this hypothesis, local field potential recordings were obtained from the hippocampus of awake, behaving knock-outs and wild-type littermates. The magnitude of theta oscillations was increased in the knock-outs, specifically in the anxiety-provoking elevated plus maze and not in a familiar environment or during rapid eye movement sleep. Theta power correlated with the fraction of time spent in the open arms, an anxiety-related behavioral variable. These results suggest a possible role for the hippocampus, and theta oscillations in particular, in the expression of anxiety in 5-HT(1A)R-deficient mice.
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Affiliation(s)
- Joshua A Gordon
- Center for Neurobiology and Behavior, Department of Psychiatry, Columbia University, New York, New York 10032, USA.
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46
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Abstract
The theta rhythm is the largest extracellular synchronous signal that can be recorded from the mammalian brain, and has been strongly implicated in mnemonic functions of the hippocampus. We advance the proposal that the theta rhythm represents a "tag" for short-term memory processing in the hippocampus. We propose that the hippocampus receives two main types of input, theta from ascending brainstem-diencephalo-septal systems and "information bearing" mainly from thalamocortical and cortical systems. The temporal convergence of activity of these two systems results in the encoding of information in the hippocampus, primarily reaching it via cortical routes. By analogy to processes associated with long-term potentiation (LTP), we suggest that theta represents a strong depolarizing influence on NMDA receptor-containing cells of the hippocampus. The temporal coupling of a theta-induced depolarization and the release of glutamate to these cells from intra- and extrahippocampal sources activates them. This, in turn, initiates processes leading to a (short-term) strengthening of connections between presynaptic ("information bearing") and postsynaptic neurons of the hippocampus. Theta is selectively present in the rat during active exploratory movements. During exploration, a rat continually gathers and updates information about its environment. If this information is temporally coupled to theta (as with the case of locomotion), it becomes temporarily stored in the hippocampus by mechanisms similar to the early phase of LTP (E-LTP). If the exploratory behavior of the rat goes unreinforced, these relatively short-lasting traces (1-3 h) gradually weaken and eventually fade-to be reupdated. On the other hand, if the explorations of the rat lead to rewards (or punishments), additional modulatory inputs to the hippocampus become activated and convert the short-term, theta-dependent memory, into long-term stores.
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Affiliation(s)
- Robert P Vertes
- Center for Complex Systems and Brain Sciences, Florida Atlantic University, Boca Raton, 33431, USA.
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47
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Huesa G, van den Pol AN, Finger TE. Differential distribution of hypocretin (orexin) and melanin-concentrating hormone in the goldfish brain. J Comp Neurol 2005; 488:476-91. [PMID: 15973685 DOI: 10.1002/cne.20610] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The orexigenic peptides hypocretin (orexin) and melanin-concentrating hormone (MCH) are involved in the control of food intake and in other homeostatic functions including sleep and arousal. In this article we study the distribution of these peptides in the brain of the goldfish (Carassius auratus), focusing on those regions particularly related to feeding, sleep, and arousal. Although the general distribution of these peptides in goldfish shows many similarities to those described previously in other species, we observed some noteworthy differences. As in other vertebrates, the peptidergic somata lie in the anterolateral hypothalamus. In goldfish, both hypocretin and MCH immunoreactive cell bodies project fibers to the ventral telencephalon, thalamus, and hypothalamus. At mesencephalic levels fibers reach the deep layers of the optic tectum and also course sparsely through the mesencephalic tegmentum. In contrast to the strong innervation of locus coeruleus and raphe in mammal, the MCH and hypocretin systems in goldfish barely innervate these aminergic populations related to the regulation of sleep and arousal. MCH, but not hypocretin, immunoreactive fibers terminate substantially in the sensory layer of the vagal gustatory lobe of goldfish, while both peptidergic systems distribute to the primary visceral sensory areas of the medulla and pons. The strong involvement of these peptidergic systems with the hypothalamus and general visceral nuclei, but not with locus coeruleus or raphe nuclei support the view that these peptides originally played a role in regulation of energy balance and evolved secondarily to influence sleep-wakefulness systems in amniote vertebrates.
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Affiliation(s)
- Gema Huesa
- Department of Cell and Developmental Biology, University of Colorado at Denver, Health Sciences Center, Aurora, Colorado 80045, USA
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48
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Li S, Varga V, Sik A, Kocsis B. GABAergic control of the ascending input from the median raphe nucleus to the limbic system. J Neurophysiol 2005; 94:2561-74. [PMID: 15944232 PMCID: PMC1224729 DOI: 10.1152/jn.00379.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The median raphe nucleus (MRN) is the primary source of serotonergic afferents to the limbic system that are generally considered to suppress hippocampal theta oscillations. GABA receptors are expressed in the MRN by serotonergic and nonserotonergic cells, including GABAergic and glutamatergic neurons. This study investigated the mechanisms by which the fluctuating GABA tone in the MRN leads to induction or suppression of hippocampal theta rhythm. We found that MRN application of the GABA(A) agonist muscimol (0.05-1.0 mM) or GABA(B) agonist baclofen (0.2 mM) by reverse microdialysis had strong theta promoting effects. The GABA(A) antagonist bicuculline infused in low concentrations (0.1, 0.2 mM) eliminated theta rhythm. A short period of theta activity of higher than normal frequency preceded hippocampal desynchronization in 46% of rats. Bicuculline in larger concentrations (0.5, 1.0, 2.0 mM) resulted in a biphasic response of an initial short (<10 min) hippocampal desynchronization followed by stable theta rhythm that lasted as long as the infusion continued. The frequency and amplitude of theta waves were higher than in control recordings and the oscillations showed a conspicuous intermittent character. Hippocampal theta rhythm elicited by MRN administration of bicuculline could be completely (0.5 mM bicuculline) or partially (1.0 mM bicuculline) blocked by simultaneous infusion of the GABA(B) antagonist CGP35348. Our findings suggest that the GABAergic network may have two opposing functions in the MRN: relieving the theta-generators from serotonergic inhibition and regulating the activity of a theta-promoting circuitry by the fluctuating GABA tone. The two mechanisms may be involved in different functions.
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Affiliation(s)
- Shaomin Li
- Laboratory of Neurophysiology, Departments of Psychiatry at Massachusetts Mental Health Center and Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, USA
| | - Viktor Varga
- Laboratory of Neurophysiology, Departments of Psychiatry at Massachusetts Mental Health Center and Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, USA
- National Institute of Neurosurgery, Budapest Hungary
| | | | - Bernat Kocsis
- Laboratory of Neurophysiology, Departments of Psychiatry at Massachusetts Mental Health Center and Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, USA
- National Institute of Neurosurgery, Budapest Hungary
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Olvera-Cortés E, Guevara MA, González-Burgos I. Increase of the hippocampal theta activity in the Morris water maze reflects learning rather than motor activity. Brain Res Bull 2004; 62:379-84. [PMID: 15168902 DOI: 10.1016/j.brainresbull.2003.10.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2003] [Revised: 10/07/2003] [Accepted: 10/14/2003] [Indexed: 11/21/2022]
Abstract
The change in the percentage of rat hippocampal high-frequency theta activity from being immobile and awake to swimming behaviour was calculated for three groups of rats, trained in either place learning, cue learning or egocentric learning in the Morris water maze. The place-learning-trained rats showed an increase in the percentage of theta activity, along with a significant reduction in escape latency over the last 3 days of training. No changes were observed in the other two groups. Because the motor activity displayed by the three groups of rats was similar, we suggest that the increase in the percentage of theta activity concomitant with place-learning training could be related to the processing of information by the hippocampus, rather than to the displayed motor activity.
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Affiliation(s)
- Esther Olvera-Cortés
- Laboratorio de Neurofisiología Experimental, Centro de Investigación Biomédica de Michoacán, Instituto Mexicano del Seguro Social, AP 7-70, CP 58261 Morelia, Mich., Mexico.
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50
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Hajos M, Hoffmann WE, Weaver RJ. Regulation of septo-hippocampal activity by 5-hydroxytryptamine(2C) receptors. J Pharmacol Exp Ther 2003; 306:605-15. [PMID: 12734389 DOI: 10.1124/jpet.103.051169] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It is established that the serotonin system modulates hippocampal functions by regulating neuronal activity of both the medial septum and hippocampus. Inhibition of serotonin neurons leads to theta oscillation of septal neurons and theta wave activity in the hippocampus, indicating a tonic regulation of the septo-hippocampal system by serotonin neurons. Because the postsynaptic 5-hydroxytryptamine (5-HT) receptor subtypes mediating this tonic inhibition have not been identified, a putative role of 5-HT2C receptors has been evaluated in the present study. Extracellular single units were recorded from the medial septum/vertical limb of diagonal band (MS/DBv) and hippocampal CA1 or dentate gyrus with simultaneous hippocampal EEG recordings from anesthetized rats. Intravenous administration of 5-HT2C receptor agonists 1-(3-chlorophenyl)piperazine dihydrochloride (m-CPP) and [S]-2-(chloro-5-fluoro-indol-1-yl)-1-methyl-ethylamine fumarate (Ro 60-0175) dose dependently inhibited firing activity most of the recorded MS/DBv neurons and abolished theta oscillation in all tested MS/DBv and hippocampal neurons. Parallel to inhibition of theta oscillation of MS/DBv neurons, hippocampal EEG activity was desynchronized and its power spectrum was shifted to lower frequencies. The selective 5-HT2C receptor antagonist 6-chloro-5-methyl-1-[2-(2-methylpyridyl-3-oxy)-pyrid-5-yl carbomyl] indoline (SB-242084) [but not the 5-HT2B antagonist 2-amino-4-(4-fluoronaphth-1-yl)-6-isopropyl-pyrimidine (RS-127445) or 5-HT2A antagonist R-(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)-ethyl]-4-piperidinemethanol (MDL-100907)] reversed the action of 5-HT2C receptor agonists. Furthermore, in control rats 5-HT2C receptor antagonists [SB-242084 and 5-methyl-1-(3-pyridil-carbamoyl)-1,2,3,5-tetrahydropyr-rolo[2,3-f]indole hydrochloride (SB-206553)] induced or enhanced theta oscillation in MS/DBv and hippocampal neurons and theta wave activity of the hippocampus. These findings provide evidence for a tonic regulation of the activity and theta oscillation of the septo-hippocampal system via 5-HT2C receptors in the anesthetized rat, indicating that pharmacological interactions with these receptors could modulate various physiological and pathological processes associated with limbic theta activity.
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Affiliation(s)
- Mihaly Hajos
- Neurobiology, Pharmacia Corporation, Kalamazoo, MI 49007, USA.
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