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Corradetti D, Bernardi A, Corradetti R. Deep learning models for atypical serotonergic cells recognition. J Neurosci Methods 2024; 407:110158. [PMID: 38703797 DOI: 10.1016/j.jneumeth.2024.110158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/15/2024] [Accepted: 04/28/2024] [Indexed: 05/06/2024]
Abstract
BACKGROUND The serotonergic system modulates brain processes via functionally distinct subpopulations of neurons with heterogeneous properties, including their electrophysiological activity. In extracellular recordings, serotonergic neurons to be investigated for their functional properties are commonly identified on the basis of "typical" features of their activity, i.e. slow regular firing and relatively long duration of action potentials. Thus, due to the lack of equally robust criteria for discriminating serotonergic neurons with "atypical" features from non-serotonergic cells, the physiological relevance of the diversity of serotonergic neuron activities results largely understudied. NEW METHODS We propose deep learning models capable of discriminating typical and atypical serotonergic neurons from non-serotonergic cells with high accuracy. The research utilized electrophysiological in vitro recordings from serotonergic neurons identified by the expression of fluorescent proteins specific to the serotonergic system and non-serotonergic cells. These recordings formed the basis of the training, validation, and testing data for the deep learning models. The study employed convolutional neural networks (CNNs), known for their efficiency in pattern recognition, to classify neurons based on the specific characteristics of their action potentials. RESULTS The models were trained on a dataset comprising 27,108 original action potential samples, alongside an extensive set of 12 million synthetic action potential samples, designed to mitigate the risk of overfitting the background noise in the recordings, a potential source of bias. Results show that the models achieved high accuracy and were further validated on "non-homogeneous" data, i.e., data unknown to the model and collected on different days from those used for the training of the model, to confirm their robustness and reliability in real-world experimental conditions. COMPARISON WITH EXISTING METHODS Conventional methods for identifying serotonergic neurons allow recognition of serotonergic neurons defined as typical. Our model based on the analysis of the sole action potential reliably recognizes over 94% of serotonergic neurons including those with atypical features of spike and activity. CONCLUSION The model is ready for use in experiments conducted with the here described recording parameters. We release the codes and procedures allowing to adapt the model to different acquisition parameters or for identification of other classes of spontaneously active neurons.
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Affiliation(s)
- Daniele Corradetti
- Grupo de Fisica Matematica, Instituto Superior Tecnico, Av. Rovisco Pais, Lisboa, 1049-001, Portugal; Departamento de Matematica, Universidade do Algarve, Campus de Gambelas, Faro, 8005-139, Faro, Portugal.
| | | | - Renato Corradetti
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), University of Florence, Viale G. Pieraccini 6, Firenze, 50139, Toscana, Italy.
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Gugel A, Ingebretsen EA, Hake HS, Gantz SC. LC-derived excitatory synaptic transmission to dorsal raphe serotonin neurons is inhibited by activation of alpha2-adrenergic receptors. Neuropsychopharmacology 2024; 49:1014-1023. [PMID: 38368493 PMCID: PMC11039657 DOI: 10.1038/s41386-024-01824-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/25/2024] [Accepted: 02/05/2024] [Indexed: 02/19/2024]
Abstract
In the central nervous system, noradrenaline transmission controls the degree to which we are awake, alert, and attentive. Aberrant noradrenaline transmission is associated with pathological forms of hyper- and hypo-arousal that present in numerous neuropsychiatric disorders often associated with dysfunction in serotonin transmission. In vivo, noradrenaline regulates the release of serotonin because noradrenergic input drives the serotonin neurons to fire action potentials via activation of excitatory α1-adrenergic receptors (α1-AR). Despite the critical influence of noradrenaline on the activity of dorsal raphe serotonin neurons, the source of noradrenergic afferents has not been resolved and the presynaptic mechanisms that regulate noradrenaline-dependent synaptic transmission have not been described. Using an acute brain slice preparation from male and female mice and electrophysiological recordings from dorsal raphe serotonin neurons, we found that selective optogenetic activation of locus coeruleus terminals in the dorsal raphe was sufficient to produce an α1-AR-mediated excitatory postsynaptic current (α1-AR-EPSC). Activation of inhibitory α2-adrenergic receptors (α2-AR) with UK-14,304 eliminated the α1-AR-EPSC via presynaptic inhibition of noradrenaline release, likely via inhibition of voltage-gated calcium channels. In a subset of serotonin neurons, activation of postsynaptic α2-AR produced an outward current through activation of GIRK potassium conductance. Further, in vivo activation of α2-AR by systemic administration of clonidine reduced the expression of c-fos in the dorsal raphe serotonin neurons, indicating reduced neural activity. Thus, α2-AR are critical regulators of serotonin neuron excitability.
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Affiliation(s)
- Aleigha Gugel
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, 52242, USA
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, 52242, USA
| | - Erik A Ingebretsen
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, 52242, USA
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, 52242, USA
| | - Holly S Hake
- National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Stephanie C Gantz
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, 52242, USA.
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, 52242, USA.
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Laurencin C, Lancelot S, Brosse S, Mérida I, Redouté J, Greusard E, Lamberet L, Liotier V, Le Bars D, Costes N, Thobois S, Boulinguez P, Ballanger B. Noradrenergic alterations in Parkinson's disease: a combined 11C-yohimbine PET/neuromelanin MRI study. Brain 2024; 147:1377-1388. [PMID: 37787503 PMCID: PMC10994534 DOI: 10.1093/brain/awad338] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 09/05/2023] [Accepted: 09/19/2023] [Indexed: 10/04/2023] Open
Abstract
Degeneration of the noradrenergic system is now considered a pathological hallmark of Parkinson's disease, but little is known about its consequences in terms of parkinsonian manifestations. Here, we evaluated two aspects of the noradrenergic system using multimodal in vivo imaging in patients with Parkinson's disease and healthy controls: the pigmented cell bodies of the locus coeruleus with neuromelanin sensitive MRI; and the density of α2-adrenergic receptors (ARs) with PET using 11C-yohimbine. Thirty patients with Parkinson's disease and 30 age- and sex-matched healthy control subjects were included. The characteristics of the patients' symptoms were assessed using the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS). Patients showed reduced neuromelanin signal intensity in the locus coeruleus compared with controls and diminished 11C-yohimbine binding in widespread cortical regions, including the motor cortex, as well as in the insula, thalamus and putamen. Clinically, locus coeruleus neuronal loss was correlated with motor (bradykinesia, motor fluctuations, tremor) and non-motor (fatigue, apathy, constipation) symptoms. A reduction of α2-AR availability in the thalamus was associated with tremor, while a reduction in the putamen, the insula and the superior temporal gyrus was associated with anxiety. These results highlight a multifaceted alteration of the noradrenergic system in Parkinson's disease since locus coeruleus and α2-AR degeneration were found to be partly uncoupled. These findings raise important issues about noradrenergic dysfunction that may encourage the search for new drugs targeting this system, including α2-ARs, for the treatment of Parkinson's disease.
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Affiliation(s)
- Chloé Laurencin
- Lyon Neuroscience Research Center (CRNL), INSERM U1028, CNRS UMR5292, University Lyon 1, F-69000 Lyon, France
- Department of Neurology C, Expert Parkinson Centre, Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital, NS-Park/F-CRIN, 69500 Bron, France
| | - Sophie Lancelot
- Lyon Neuroscience Research Center (CRNL), INSERM U1028, CNRS UMR5292, University Lyon 1, F-69000 Lyon, France
- CERMEP-Imagerie du Vivant, PET-MRI Department, 69500 Bron, France
| | - Sarah Brosse
- Lyon Neuroscience Research Center (CRNL), INSERM U1028, CNRS UMR5292, University Lyon 1, F-69000 Lyon, France
| | - Inés Mérida
- CERMEP-Imagerie du Vivant, PET-MRI Department, 69500 Bron, France
| | - Jérôme Redouté
- CERMEP-Imagerie du Vivant, PET-MRI Department, 69500 Bron, France
| | - Elise Greusard
- CERMEP-Imagerie du Vivant, PET-MRI Department, 69500 Bron, France
| | - Ludovic Lamberet
- CERMEP-Imagerie du Vivant, PET-MRI Department, 69500 Bron, France
| | | | - Didier Le Bars
- CERMEP-Imagerie du Vivant, PET-MRI Department, 69500 Bron, France
| | - Nicolas Costes
- CERMEP-Imagerie du Vivant, PET-MRI Department, 69500 Bron, France
| | - Stéphane Thobois
- Department of Neurology C, Expert Parkinson Centre, Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital, NS-Park/F-CRIN, 69500 Bron, France
- Institut des Sciences Cognitives Marc Jeannerod, UMR 5229, CNRS, 69500 Bron, France
| | - Philippe Boulinguez
- Lyon Neuroscience Research Center (CRNL), INSERM U1028, CNRS UMR5292, University Lyon 1, F-69000 Lyon, France
| | - Bénédicte Ballanger
- Lyon Neuroscience Research Center (CRNL), INSERM U1028, CNRS UMR5292, University Lyon 1, F-69000 Lyon, France
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Matt RA, Martin RS, Evans AK, Gever JR, Vargas GA, Shamloo M, Ford AP. Locus Coeruleus and Noradrenergic Pharmacology in Neurodegenerative Disease. Handb Exp Pharmacol 2023. [PMID: 37495851 DOI: 10.1007/164_2023_677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Adrenoceptors (ARs) throughout the brain are stimulated by noradrenaline originating mostly from neurons of the locus coeruleus, a brainstem nucleus that is ostensibly the earliest to show detectable pathology in neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. The α1-AR, α2-AR, and β-AR subtypes expressed in target brain regions and on a range of cell populations define the physiological responses to noradrenaline, which includes activation of cognitive function in addition to modulation of neurometabolism, cerebral blood flow, and neuroinflammation. As these heterocellular functions are critical for maintaining brain homeostasis and neuronal health, combating the loss of noradrenergic tone from locus coeruleus degeneration may therefore be an effective treatment for both cognitive symptoms and disease modification in neurodegenerative indications. Two pharmacologic approaches are receiving attention in recent clinical studies: preserving noradrenaline levels (e.g., via reuptake inhibition) and direct activation of target adrenoceptors. Here, we review the expression and role of adrenoceptors in the brain, the preclinical studies which demonstrate that adrenergic stimulation can support cognitive function and cerebral health by reversing the effects of noradrenaline depletion, and the human data provided by pharmacoepidemiologic analyses and clinical trials which together identify adrenoceptors as promising targets for the treatment of neurodegenerative disease.
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Affiliation(s)
| | | | - Andrew K Evans
- Department of Neurosurgery, Stanford University School of Medicine, Palo Alto, CA, USA
| | | | | | - Mehrdad Shamloo
- Department of Neurosurgery, Stanford University School of Medicine, Palo Alto, CA, USA
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Majdi A, Asamoah B, Mc Laughlin M. Reinterpreting published tDCS results in terms of a cranial and cervical nerve co-stimulation mechanism. Front Hum Neurosci 2023; 17:1101490. [PMID: 37415857 PMCID: PMC10320219 DOI: 10.3389/fnhum.2023.1101490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 05/31/2023] [Indexed: 07/08/2023] Open
Abstract
Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation method that has been used to alter cognition in hundreds of experiments. During tDCS, a low-amplitude current is delivered via scalp electrodes to create a weak electric field in the brain. The weak electric field causes membrane polarization in cortical neurons directly under the scalp electrodes. It is generally assumed that this mechanism causes the observed effects of tDCS on cognition. However, it was recently shown that some tDCS effects are not caused by the electric field in the brain but rather via co-stimulation of cranial and cervical nerves in the scalp that also have neuromodulatory effects that can influence cognition. This peripheral nerve co-stimulation mechanism is not controlled for in tDCS experiments that use the standard sham condition. In light of this new evidence, results from previous tDCS experiments could be reinterpreted in terms of a peripheral nerve co-stimulation mechanism. Here, we selected six publications that reported tDCS effects on cognition and attributed the effects to the electric field in the brain directly under the electrode. We then posed the question: given the known neuromodulatory effects of cranial and cervical nerve stimulation, could the reported results also be understood in terms of tDCS peripheral nerve co-stimulation? We present our re-interpretation of these results as a way to stimulate debate within the neuromodulation field and as a food-for-thought for researchers designing new tDCS experiments.
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Affiliation(s)
- Alireza Majdi
- Exp ORL, Department of Neuroscience, Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Boateng Asamoah
- Exp ORL, Department of Neuroscience, Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Myles Mc Laughlin
- Exp ORL, Department of Neuroscience, Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
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Berger A, Vespa S, Dricot L, Dumoulin M, Iachim E, Doguet P, Vandewalle G, El Tahry R. How Is the Norepinephrine System Involved in the Antiepileptic Effects of Vagus Nerve Stimulation? Front Neurosci 2021; 15:790943. [PMID: 34924947 PMCID: PMC8675889 DOI: 10.3389/fnins.2021.790943] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 11/11/2021] [Indexed: 01/09/2023] Open
Abstract
Vagus Nerve Stimulation (VNS) is an adjunctive treatment for patients suffering from inoperable drug-resistant epilepsy. Although a complete understanding of the mediators involved in the antiepileptic effects of VNS and their complex interactions is lacking, VNS is known to trigger the release of neurotransmitters that have seizure-suppressing effects. In particular, norepinephrine (NE) is a neurotransmitter that has been associated with the clinical effects of VNS by preventing seizure development and by inducing long-term plastic changes that could restore a normal function of the brain circuitry. However, the biological requisites to become responder to VNS are still unknown. In this review, we report evidence of the critical involvement of NE in the antiepileptic effects of VNS in rodents and humans. Moreover, we emphasize the hypothesis that the functional integrity of the noradrenergic system could be a determining factor to obtain clinical benefits from the therapy. Finally, encouraging avenues of research involving NE in VNS treatment are discussed. These could lead to the personalization of the stimulation parameters to maximize the antiepileptic effects and potentially improve the response rate to the therapy.
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Affiliation(s)
- Alexandre Berger
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium.,Synergia Medical SA, Mont-Saint-Guibert, Belgium.,GIGA-Cyclotron Research Center-In Vivo Imaging, University of Liège, Liège, Belgium
| | - Simone Vespa
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - Laurence Dricot
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - Manon Dumoulin
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - Evelina Iachim
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium.,Department of Pediatric Neurology, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
| | | | - Gilles Vandewalle
- GIGA-Cyclotron Research Center-In Vivo Imaging, University of Liège, Liège, Belgium
| | - Riëm El Tahry
- Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium.,Center for Refractory Epilepsy, Department of Neurology, Cliniques Universitaires Saint-Luc, Brussels, Belgium
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Flores RA, Dos-Santos RC, Steinbach R, Rodrigues-Santos I, de Jesus AA, Antunes-Rodrigues J, Paschoalini MA. α-1 Adrenoceptor Activation in the Dorsal Raphe Nucleus Decreases Food Intake in Fasted Rats. Front Physiol 2021; 12:775070. [PMID: 34899395 PMCID: PMC8656260 DOI: 10.3389/fphys.2021.775070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/21/2021] [Indexed: 01/12/2023] Open
Abstract
The dorsal raphe (DR) nucleus is involved in a myriad of physiological functions, such as the control of sleep-wake cycle, motivation, pain, energy balance, and food intake. We have previously demonstrated that in ad libitum fed rats the intra-DR administration of phenylephrine, an α-1 receptor agonist, does not affect food intake, whereas clonidine, an α-2 receptor agonist, potently stimulates food intake. These results indicated that in fed rats an increased adrenergic tonus blocked food intake, since the activation of α-2 auto-receptors, which decreases pre-synaptic release of adrenaline/noradrenaline, affected food intake. Thus, in this study we assessed whether the response to adrenergic stimuli would differ after overnight fasting, a situation of low adrenergic activity in the DR. Intra-DR administration of adrenaline and noradrenaline blocked food intake evoked by overnight fasting. Similarly, phenylephrine administration decreased hunger-induced food intake. These changes in food intake were accompanied by changes in other behaviors, such as increased immobility time and feeding duration. On the other hand, intra-DR administration of clonidine did not affect food-intake or associated behaviors. These results further support the hypothesis that in fed animals, increased adrenergic tonus in DR neurons inhibiting feeding, while in fasted rats the adrenergic tonus decreases and favors food intake. These data indicate a possible mechanism through which adrenergic input to the DRN contributes to neurobiology of feeding.
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Affiliation(s)
- Rafael Appel Flores
- Department of Physiology, Ribeirão Preto School of Medicine, São Paulo University, Ribeirão Preto, Brazil.,Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Raoni Conceição Dos-Santos
- Department of Physiology, Ribeirão Preto School of Medicine, São Paulo University, Ribeirão Preto, Brazil
| | - Renata Steinbach
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Isabelle Rodrigues-Santos
- Department of Physiology, Ribeirão Preto School of Medicine, São Paulo University, Ribeirão Preto, Brazil
| | - Aline Alves de Jesus
- Department of Physiology, Ribeirão Preto School of Medicine, São Paulo University, Ribeirão Preto, Brazil
| | - José Antunes-Rodrigues
- Department of Physiology, Ribeirão Preto School of Medicine, São Paulo University, Ribeirão Preto, Brazil
| | - Marta Aparecida Paschoalini
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
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Dysfunction of the serotonergic system in the brain of synapsin triple knockout mice is associated with behavioral abnormalities resembling synapsin-related human pathologies. Prog Neuropsychopharmacol Biol Psychiatry 2021; 105:110135. [PMID: 33058959 DOI: 10.1016/j.pnpbp.2020.110135] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/31/2020] [Accepted: 10/06/2020] [Indexed: 11/23/2022]
Abstract
Synapsins (Syns) are a family of phosphoproteins associated with synaptic vesicles (SVs). Their main function is to regulate neurotransmitter release by maintaining a reserve pool of SVs at the presynaptic terminal. Previous studies reported that the deletion of one or more Syn genes in mice results in an epileptic phenotype and autism-related behavioral abnormalities. Here we aimed at characterizing the behavioral phenotype and neurobiological correlates of the deletion of Syns in a Syn triple knockout (TKO) mouse model. Wild type (WT) and TKO mice were tested in the open field, novelty suppressed feeding, light-dark box, forced swim, tail suspension and three-chamber sociability tests. Using in vivo electrophysiology, we recorded the spontaneous activity of dorsal raphe nucleus (DRN) serotonin (5-HT) and ventral tegmental area (VTA) dopamine (DA) neurons. Levels of 5-HT and DA in the frontal cortex and hippocampus of WT and TKO mice were also assessed using a High-Performance Liquid Chromatography. TKO mice displayed hyperactivity and impaired social and anxiety-like behavior. Behavioral dysfunctions were accompanied by reduced firing activity of DRN 5-HT, but not VTA DA, neurons. TKO mice also showed increased responsiveness of DRN 5-HT-1A autoreceptors, measured as a reduced dose of the 5-HT-1A agonist 8-OH-DPAT necessary to inhibit DRN 5-HT firing activity by 50%. Finally, hippocampal 5-HT levels were lower in TKO than in WT mice. Overall, Syns deletion in mice leads to a reduction in DRN 5-HT firing activity and hippocampal 5-HT levels along with behavioral alterations reminiscent of human neuropsychiatric conditions associated with Syn dysfunction.
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Delcourte S, Etievant A, Haddjeri N. Role of central serotonin and noradrenaline interactions in the antidepressants' action: Electrophysiological and neurochemical evidence. PROGRESS IN BRAIN RESEARCH 2021; 259:7-81. [PMID: 33541681 DOI: 10.1016/bs.pbr.2021.01.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The development of antidepressant drugs, in the last 6 decades, has been associated with theories based on a deficiency of serotonin (5-HT) and/or noradrenaline (NA) systems. Although the pathophysiology of major depression (MD) is not fully understood, numerous investigations have suggested that treatments with various classes of antidepressant drugs may lead to an enhanced 5-HT and/or adapted NA neurotransmissions. In this review, particular morpho-physiological aspects of these systems are first considered. Second, principal features of central 5-HT/NA interactions are examined. In this regard, the effects of the acute and sustained antidepressant administrations on these systems are discussed. Finally, future directions including novel therapeutic strategies are proposed.
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Affiliation(s)
- Sarah Delcourte
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
| | - Adeline Etievant
- Integrative and Clinical Neurosciences EA481, University of Bourgogne Franche-Comté, Besançon, France
| | - Nasser Haddjeri
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France.
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Flores RA, Steinbach R, Pedroso JAB, Metzger M, Donato J, Paschoalini MA. Injections of the α-2 adrenoceptor agonist clonidine into the dorsal raphe nucleus increases food intake in satiated rats. Neuropharmacology 2020; 182:108397. [PMID: 33188843 DOI: 10.1016/j.neuropharm.2020.108397] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 11/04/2020] [Accepted: 11/07/2020] [Indexed: 10/23/2022]
Abstract
The present study aimed to evaluate the effects of pharmacological manipulation of α-adrenergic agonists in the dorsal raphe nucleus (DR) on food intake in satiated rats. Adult male Wistar rats with chronically implanted cannula in the DR were injected with adrenaline (AD) or noradrenaline (NA) (both at doses of 6, 20 and 60 nmol), or α-1 adrenergic agonist phenylephrine (PHE) or α-2 adrenergic agonist clonidine (CLO) (both at doses of 6 and 20 nmol). The injections were followed by the evaluation of ingestive behaviors. Food and water intake were evaluated for 60 min. Administration of AD and NA at 60 nmol and CLO at 20 nmol increased food intake and decreased latency to start consumption in satiated rats. The ingestive behavior was not significantly affected by PHE treatment in the DR. CLO treatment increased Fos expression in the arcuate nucleus (ARC) and paraventricular nucleus of the hypothalamus (PVN) in rats that were allowed to eat during the experimental recording (AF group). However, when food was not offered during the experiment (WAF group), PVN neurons were not activated, whereas, neuronal activity remained high in the ARC when compared to control group. Noteworthy, ARC POMC neurons expressed Fos in the AF group. However, double-labeled POMC/Fos cells were absent in the ARC of the WAF group, although an increase in Fos expression was observed in non-POMC cells after CLO injections in the WAF group. In conclusion, the data from the present study highlight that the pharmacological activation of DR α-adrenoceptors affects food intake in satiated rats. The feeding response evoked by CLO injections into DR was similar to that induced by NA or AD injections, suggesting that the hyperphagia after NA or AD treatment depends on α-2 adrenoceptors activation. Finally, we have demonstrated that CLO injections into DR impact neuronal activity in the ARC, possibly evoking a homeostatic response toward food intake.
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Affiliation(s)
- Rafael Appel Flores
- Department of Physiological Sciences, Center of Biological Sciences - CCB, Federal University of Santa Catarina (UFSC), 88040-970, Florianópolis, SC, Brazil.
| | - Renata Steinbach
- Department of Physiological Sciences, Center of Biological Sciences - CCB, Federal University of Santa Catarina (UFSC), 88040-970, Florianópolis, SC, Brazil.
| | - João A B Pedroso
- Department of Physiology & Biophysics, Institute of Biomedical Sciences, University of São Paulo, 05508-900, São Paulo, SP, Brazil.
| | - Martin Metzger
- Department of Physiology & Biophysics, Institute of Biomedical Sciences, University of São Paulo, 05508-900, São Paulo, SP, Brazil.
| | - José Donato
- Department of Physiology & Biophysics, Institute of Biomedical Sciences, University of São Paulo, 05508-900, São Paulo, SP, Brazil.
| | - Marta Aparecida Paschoalini
- Department of Physiological Sciences, Center of Biological Sciences - CCB, Federal University of Santa Catarina (UFSC), 88040-970, Florianópolis, SC, Brazil.
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Pharmacological depletion of serotonin and norepinephrine with para-chlorophenylalanine and alpha-methyl-p-tyrosine reverses the antidepressant-like effects of adolescent caffeine exposure in the male rat. Behav Pharmacol 2020; 31:768-775. [PMID: 32897889 DOI: 10.1097/fbp.0000000000000588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Adolescent exposure to caffeine has been shown to decrease immobility in the forced swim test, suggesting and antidepressant-like effect of caffeine; however, studies have produced different results with regard to caffeine-induced active behaviors. The present study attempted to clarify the possible neurochemical mechanisms of caffeine's action by selectively depleting norepinephrine with alpha-methyl-p-tyrosine or serotonin with para-chlorophenylalanine in two separate experiments and assessing the ability for caffeine to alter anxiety-like and depressive-like behavior. Caffeine-treated adolescent male rats were exposed to caffeine (0.25 g/L) in their drinking water beginning on P28. A-methyl-p-tyrosine, para-chlorophenylalanine, or saline were administered prior to light-dark, open field, and forced swim testing beginning on P45. Caffeine-induced reductions in immobility and increases in swimming in the forced swim test were reversed by both a-methyl-p-tyrosine and para-chlorophenylalanine. Caffeine-induced increases in crosses and rears were reversed by para-chlorophenylalanine but not alpha-methyl-p-tyrosine, whereas caffeine-induced increases in transitions in the LD test were reversed by alpha-methyl-p-tyrosine but not para-chlorophenylalanine. Taken together, these results suggest that caffeine-induced decreases in immobility in male rats requires both norepinephrine and serotonin as depletion of either prevents the induction of immobility by chronic caffeine.
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Effect of combined treatment with aripiprazole and antidepressants on the MK-801-induced deficits in recognition memory in novel recognition test and on the release of monoamines in the rat frontal cortex. Behav Brain Res 2020; 393:112769. [PMID: 32535184 DOI: 10.1016/j.bbr.2020.112769] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 03/11/2020] [Accepted: 05/13/2020] [Indexed: 01/23/2023]
Abstract
According to preclinical and clinical studies, the antidepressant-induced increase in the activity of atypical antipsychotics may efficiently improve the treatment of negative and some cognitive symptoms of schizophrenia. In the present study, we aimed to evaluate the effects of the antidepressants escitalopram and mirtazapine and the atypical antipsychotic drug aripiprazole, administered separately or in combination, on the MK-801-induced deficits in the recognition memory test and on the extracellular levels of monoamines and their metabolites in the rat frontal cortex. Based on the results of the behavioral tests, co-treatment with an ineffective dose of aripiprazole (0.1 mg/kg) and escitalopram (2.5 and 5 mg/kg) or mirtazapine (5 mg/kg) abolished the deficits evoked by MK-801 in the novel object recognition test, and those effects were blocked by the 5-HT1A receptor antagonist (WAY 100,635) or the dopamine D1 receptor antagonist (SCH 23,390). Moreover, co-treatment with aripiprazole (0.3 mg/kg) and escitalopram (5 mg/kg) significantly increased the levels of noradrenaline and serotonin, decreased the level of its metabolite, and did not alter level of dopamine, but decreased the levels of its metabolites. In addition, co-treatment with aripiprazole (0.3 mg/kg) and mirtazapine (10 mg/kg) significantly increased the level of noradrenaline, did not change the levels of dopamine and serotonin, but increased the levels of their metabolites. Based on these results, the increase in the extracellular levels of noradrenaline or serotonin in the cortex induced by co-treatment with an antidepressant and aripiprazole may be very important for the pharmacotherapy of negative and some cognitive symptoms of schizophrenia.
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13
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Sugiyama E, Skelly AN, Suematsu M, Sugiura Y. In situ imaging of monoamine localization and dynamics. Pharmacol Ther 2020; 208:107478. [DOI: 10.1016/j.pharmthera.2020.107478] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 11/22/2019] [Indexed: 01/06/2023]
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14
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Gantz SC, Moussawi K, Hake HS. Delta glutamate receptor conductance drives excitation of mouse dorsal raphe neurons. eLife 2020; 9:e56054. [PMID: 32234214 PMCID: PMC7180053 DOI: 10.7554/elife.56054] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 04/01/2020] [Indexed: 01/04/2023] Open
Abstract
The dorsal raphe nucleus is the predominant source of central serotonin, where neuronal activity regulates complex emotional behaviors. Action potential firing of serotonin dorsal raphe neurons is driven via α1-adrenergic receptors (α1-AR) activation. Despite this crucial role, the ion channels responsible for α1-AR-mediated depolarization are unknown. Here, we show in mouse brain slices that α1-AR-mediated excitatory synaptic transmission is mediated by the ionotropic glutamate receptor homolog cation channel, delta glutamate receptor 1 (GluD1). GluD1R-channels are constitutively active under basal conditions carrying tonic inward current and synaptic activation of α1-ARs augments tonic GluD1R-channel current. Further, loss of dorsal raphe GluD1R-channels produces an anxiogenic phenotype. Thus, GluD1R-channels are responsible for α1-AR-dependent induction of persistent pacemaker-type firing of dorsal raphe neurons and regulate dorsal raphe-related behavior. Given the widespread distribution of these channels, ion channel function of GluD1R as a regulator of neuronal excitability is proposed to be widespread in the nervous system.
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Affiliation(s)
- Stephanie C Gantz
- National Institute on Drug Abuse Intramural Research Program, National Institutes of HealthBaltimoreUnited States
- Center on Compulsive Behaviors, National Institutes of HealthBethesdaUnited States
| | - Khaled Moussawi
- National Institute on Drug Abuse Intramural Research Program, National Institutes of HealthBaltimoreUnited States
- Johns Hopkins Medicine, Neurology DepartmentBaltimoreUnited States
| | - Holly S Hake
- National Institute on Drug Abuse Intramural Research Program, National Institutes of HealthBaltimoreUnited States
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15
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Sugiyama E, Guerrini MM, Honda K, Hattori Y, Abe M, Källback P, Andrén PE, Tanaka KF, Setou M, Fagarasan S, Suematsu M, Sugiura Y. Detection of a High-Turnover Serotonin Circuit in the Mouse Brain Using Mass Spectrometry Imaging. iScience 2019; 20:359-372. [PMID: 31614319 PMCID: PMC6818351 DOI: 10.1016/j.isci.2019.09.036] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 07/12/2019] [Accepted: 09/24/2019] [Indexed: 12/31/2022] Open
Abstract
Monoamine neurotransmitters are released by specialized neurons regulating behavioral, motor, and cognitive functions. Although the localization of monoaminergic neurons in the brain is well known, the distribution and kinetics of monoamines remain unclear. Here, we generated a murine brain atlas of serotonin (5-HT), dopamine (DA), and norepinephrine (NE) levels using mass spectrometry imaging (MSI). We found several nuclei rich in both 5-HT and a catecholamine (DA or NE) and identified the paraventricular nucleus of the thalamus (PVT), where 5-HT and NE are co-localized. The analysis of 5-HT fluctuations in response to acute tryptophan depletion and infusion of isotope-labeled tryptophan in vivo revealed a close kinetic association between the raphe nuclei, PVT, and amygdala but not the other nuclei. Our findings imply the existence of a highly dynamic 5-HT-mediated raphe to PVT pathway that likely plays a role in the brain monoamine system. A murine brain atlas of monoamine (5-HT, DA, NE) levels was generated via MS imaging We identified several nuclei rich in both 5-HT and a catecholamine (DA or NE) The paraventricular nucleus of the thalamus (PVT) had high levels of 5-HT and NE The level of 5-HT in raphe to PVT pathway changed dynamically in response to blood Trp level
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Affiliation(s)
- Eiji Sugiyama
- Department of Biochemistry, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Matteo M Guerrini
- Laboratory for Mucosal Immunity, Center for Integrative Medical Sciences, RIKEN Yokohama Institute, Tsurumi Ward, Suehirocho, 1 Chome-7-22, Yokohama, Kanagawa Prefecture 230-0045, Japan
| | - Kurara Honda
- Department of Biochemistry, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Yuko Hattori
- Department of Biochemistry, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Manabu Abe
- Department of Animal Model Development, Brain Research Institute, Niigata University, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8585, Japan
| | - Patrik Källback
- Medical Mass Spectrometry Imaging, Department of Pharmaceutical Biosciences, Uppsala University, Box 591 BMC, 75124 Uppsala, Sweden; Science for Life Laboratory, National Resource for Mass Spectrometry Imaging, Uppsala University, Box 591 BMC, 75124 Uppsala, Sweden
| | - Per E Andrén
- Medical Mass Spectrometry Imaging, Department of Pharmaceutical Biosciences, Uppsala University, Box 591 BMC, 75124 Uppsala, Sweden; Science for Life Laboratory, National Resource for Mass Spectrometry Imaging, Uppsala University, Box 591 BMC, 75124 Uppsala, Sweden
| | - Kenji F Tanaka
- Department of Neuropsychiatry, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Mitsutoshi Setou
- Department of Cellular and Molecular Anatomy and International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Sidonia Fagarasan
- Laboratory for Mucosal Immunity, Center for Integrative Medical Sciences, RIKEN Yokohama Institute, Tsurumi Ward, Suehirocho, 1 Chome-7-22, Yokohama, Kanagawa Prefecture 230-0045, Japan
| | - Makoto Suematsu
- Department of Biochemistry, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Yuki Sugiura
- Department of Biochemistry, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan.
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16
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Montalbano A, Mlinar B, Bonfiglio F, Polenzani L, Magnani M, Corradetti R. Dual inhibitory action of trazodone on dorsal raphe serotonergic neurons through 5-HT1A receptor partial agonism and α1-adrenoceptor antagonism. PLoS One 2019; 14:e0222855. [PMID: 31557210 PMCID: PMC6763016 DOI: 10.1371/journal.pone.0222855] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 09/09/2019] [Indexed: 11/19/2022] Open
Abstract
Trazodone is an antidepressant drug with considerable affinity for 5-HT1A receptors and α1-adrenoceptors for which the drug is competitive agonist and antagonist, respectively. In this study, we used cell-attached or whole-cell patch-clamp recordings to characterize the effects of trazodone at somatodendritic 5-HT1A receptors (5-HT1AARs) and α1-adrenoceptors of serotonergic neurons in rodent dorsal raphe slices. To reveal the effects of trazodone at α1-adrenoceptors, the baseline firing of 5-HT neurons was facilitated by applying the selective α1-adrenoceptor agonist phenylephrine at various concentrations. In the absence of phenylephrine, trazodone (1–10 μM) concentration-dependently silenced neurons through activation of 5-HT1AARs. The effect was fully antagonized by the selective 5-HT1A receptor antagonist Way-100635. With 5-HT1A receptors blocked by Way-100635, trazodone (1–10 μM) concentration-dependently inhibited neuron firing facilitated by 1 μM phenylephrine. Parallel rightward shift of dose-response curves for trazodone recorded in higher phenylephrine concentrations (10–100 μM) indicated competitive antagonism at α1-adrenoceptors. Both effects of trazodone were also observed in slices from Tph2-/- mice that lack synthesis of brain serotonin, showing that the activation of 5-HT1AARs was not mediated by endogenous serotonin. In whole-cell recordings, trazodone activated 5-HT1AAR-coupled G protein-activated inwardly-rectifying (GIRK) channel conductance with weak partial agonist efficacy (~35%) compared to that of the full agonist 5-CT. Collectively our data show that trazodone, at concentrations relevant to its clinical effects, exerts weak partial agonism at 5-HT1AARs and disfacilitation of firing through α1-adrenoceptor antagonism. These two actions converge in inhibiting dorsal raphe serotonergic neuron activity, albeit with varying contribution depending on the intensity of α1-adrenoceptor stimulation.
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Affiliation(s)
- Alberto Montalbano
- NEUROFARBA—Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Università di Firenze, Firenze, Italia
| | - Boris Mlinar
- NEUROFARBA—Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Università di Firenze, Firenze, Italia
| | - Francesco Bonfiglio
- NEUROFARBA—Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Università di Firenze, Firenze, Italia
| | - Lorenzo Polenzani
- Angelini RR&D (Research, Regulatory & Development), Angelini S.p.A, S.Palomba-Pomezia (Roma), Italia
| | - Maurizio Magnani
- Angelini RR&D (Research, Regulatory & Development), Angelini S.p.A, S.Palomba-Pomezia (Roma), Italia
| | - Renato Corradetti
- NEUROFARBA—Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Università di Firenze, Firenze, Italia
- * E-mail:
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17
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Uribe-Mariño A, Castiblanco-Urbina MA, Falconi-Sobrinho LL, Dos Anjos-Garcia T, de Oliveira RC, Mendes-Gomes J, da Silva Soares R, Matthiesen M, Almada RC, de Oliveira R, Coimbra NC. The alpha- and beta-noradrenergic receptors blockade in the dorsal raphe nucleus impairs the panic-like response elaborated by medial hypothalamus neurons. Brain Res 2019; 1725:146468. [PMID: 31541642 DOI: 10.1016/j.brainres.2019.146468] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 09/13/2019] [Accepted: 09/17/2019] [Indexed: 12/16/2022]
Abstract
Dorsal raphe nucleus (DRN) neurons are reciprocally connected to the locus coeruleus (LC) and send neural pathways to the medial hypothalamus (MH). The aim of this work was to investigate whether the blockade of α1-, α2- or β-noradrenergic receptors in the DRN or the inactivation of noradrenergic neurons in the LC modify defensive behaviours organised by MH neurons. For this purpose, Wistar male rats received microinjections of WB4101, RX821002, propranolol (α1-, α2- and β-noradrenergic receptor antagonists, respectively) or physiological saline in the DRN, followed 10 min later by MH GABAA receptor blockade. Other groups of animals received DSP-4 (a noradrenergic neurotoxin), physiological saline or only a needle insertion (sham group) into the LC, and 5 days later, bicuculline or physiological saline was administered in the MH. In all these cases, after MH treatment, the frequency and duration of defensive responses were recorded over 15 min. An anterograde neural tract tracer was also deposited in the DRN. DRN neurons send pathways to lateral and dorsomedial hypothalamus. Blockade of α1- and β-noradrenergic receptors in the DRN decreased escape reactions elicited by bicuculline microinjections in the MH. In addition, a significant increase in anxiety-like behaviours was observed after the blockade of α2-noradrenergic receptors in the DRN. LC pretreatment with DSP-4 decreased both anxiety- and panic attack-like behaviours evoked by GABAA receptor blockade in the MH. In summary, the present findings suggest that the norepinephrine-mediated system modulates defensive reactions organised by MH neurons at least in part via noradrenergic receptors recruitment on DRN neurons.
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Affiliation(s)
- Andrés Uribe-Mariño
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Kraepelinstraße 2-10, 80804 Munich, Germany
| | - Maria Angélica Castiblanco-Urbina
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; Institute of Developmental Genetics, Helmholtz-Zentrum München-German Research Centre for Environmental Health (GmbH), Ingolstaedter Landstrasse 1, Neuherberg, Germany
| | - Luiz Luciano Falconi-Sobrinho
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; NAP-USP-Neurobiology of Emotions Research Centre (NuPNE), Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; Behavioural Neurosciences Institute (INeC), Avenida do Café, 2450, Ribeirão Preto 14220-030, São Paulo, Brazil
| | - Tayllon Dos Anjos-Garcia
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; NAP-USP-Neurobiology of Emotions Research Centre (NuPNE), Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; Behavioural Neurosciences Institute (INeC), Avenida do Café, 2450, Ribeirão Preto 14220-030, São Paulo, Brazil
| | - Rithiele Cristina de Oliveira
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; NAP-USP-Neurobiology of Emotions Research Centre (NuPNE), Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; Behavioural Neurosciences Institute (INeC), Avenida do Café, 2450, Ribeirão Preto 14220-030, São Paulo, Brazil
| | - Joyce Mendes-Gomes
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; NAP-USP-Neurobiology of Emotions Research Centre (NuPNE), Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; Behavioural Neurosciences Institute (INeC), Avenida do Café, 2450, Ribeirão Preto 14220-030, São Paulo, Brazil
| | - Raimundo da Silva Soares
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil
| | - Melina Matthiesen
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil
| | - Rafael Carvalho Almada
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; NAP-USP-Neurobiology of Emotions Research Centre (NuPNE), Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; Behavioural Neurosciences Institute (INeC), Avenida do Café, 2450, Ribeirão Preto 14220-030, São Paulo, Brazil
| | - Ricardo de Oliveira
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; Behavioural Neurosciences Institute (INeC), Avenida do Café, 2450, Ribeirão Preto 14220-030, São Paulo, Brazil; Health Sciences Institute, Mato Grosso Federal University Medical School (UFMT), Av. Alexandre Ferronato, 1200, Reserva 35, Setor industrial, 78550-000 Sinop, Mato Grosso, Brazil
| | - Norberto Cysne Coimbra
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; NAP-USP-Neurobiology of Emotions Research Centre (NuPNE), Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto 14049-900, São Paulo, Brazil; Behavioural Neurosciences Institute (INeC), Avenida do Café, 2450, Ribeirão Preto 14220-030, São Paulo, Brazil.
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18
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Kamińska K, Górska A, Noworyta-Sokołowska K, Wojtas A, Rogóż Z, Gołembiowska K. The effect of chronic co-treatment with risperidone and novel antidepressant drugs on the dopamine and serotonin levels in the rats frontal cortex. Pharmacol Rep 2018; 70:1023-1031. [DOI: 10.1016/j.pharep.2018.04.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 03/23/2018] [Accepted: 04/30/2018] [Indexed: 10/17/2022]
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19
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Two models of inescapable stress increase tph2 mRNA expression in the anxiety-related dorsomedial part of the dorsal raphe nucleus. Neurobiol Stress 2018. [PMID: 29520369 PMCID: PMC5842308 DOI: 10.1016/j.ynstr.2018.01.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Expression of TPH2, the rate-limiting enzyme for brain serotonin synthesis, is elevated in the dorsal raphe nucleus (DR) of depressed suicide victims. One hypothesis is that this increase in TPH2 expression is stress-induced. Here, we used an established animal model to address whether exposure to an acute stressor, inescapable tail shock (IS), increases tph2 mRNA and Tph2 protein expression, and if IS sensitizes the DR to a subsequent, heterotypic stressor. In Experiment 1, we measured tph2 mRNA expression 4 h after IS or home cage (HC) control conditions in male rats, using in situ hybridization histochemistry. In Experiment 2, we measured Tph2 protein expression 12 h or 24 h after IS using western blot. In Experiment 3, we measured tph2 mRNA expression following IS on Day 1, and cold swim stress (10 min, 15 °C) on Day 2. Inescapable tail shock was sufficient to increase tph2 mRNA expression 4 h and 28 h later, selectively in the dorsomedial DR (caudal aspect of the dorsal DR, cDRD; an area just rostral to the caudal DR, DRC) and increased Tph2 protein expression in the DRD (rostral and caudal aspects of the dorsal DR combined) 24 h later. Cold swim increased tph2 mRNA expression in the dorsomedial DR (cDRD) 4 h later. These effects were associated with increased immobility during cold swim, elevated plasma corticosterone, and a proinflammatory plasma cytokine milieu (increased interleukin (IL)-6, decreased IL-10). Our data demonstrate that two models of inescapable stress, IS and cold swim, increase tph2 mRNA expression selectively in the anxiety-related dorsomedial DR (cDRD).
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20
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Evaluation of food intake and Fos expression in serotonergic neurons of raphe nuclei after intracerebroventricular injection of adrenaline in free-feeding rats. Brain Res 2018; 1678:153-163. [DOI: 10.1016/j.brainres.2017.10.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 09/21/2017] [Accepted: 10/22/2017] [Indexed: 02/05/2023]
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21
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Zhao C, Su M, Wang Y, Li X, Zhang Y, Du X, Zhang H. Selective Modulation of K + Channel Kv7.4 Significantly Affects the Excitability of DRN 5-HT Neurons. Front Cell Neurosci 2017; 11:405. [PMID: 29311835 PMCID: PMC5735115 DOI: 10.3389/fncel.2017.00405] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 12/04/2017] [Indexed: 11/17/2022] Open
Abstract
The serotonin (5-HT) system originating in the dorsal raphe nucleus (DRN) is implicated in various mood- and emotion-related disorders, such as anxiety, fear and stress. Abnormal activity of DRN 5-HT neurons is the key factor in the development of these disorders. Here, we describe a crucial role for the Kv7.4 potassium channel in modulating DRN 5-HT neuronal excitability. We demonstrate that Kv7.4 is selectively expressed in 5-HT neurons of the DRN. Using selective Kv7.4 opener fasudil and Kv7.4 knock-out mice, we demonstrate that Kv7.4 is a potent modulator of DRN 5-HT neuronal excitability. Furthermore, we demonstrate that the cellular redox signaling mechanism is involved in this 5-HT activation of Kv7.4. The current study suggests a new strategy for treating psychiatric disorders related to altered activity of DRN 5-HT neurons using K+ channel modulators.
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Affiliation(s)
- Chen Zhao
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of Neural and Vascular Biology, Ministry of Education, The Key Laboratory of New Drug Pharmacology and Toxicology, Shijiazhuang, China
| | - Min Su
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of Neural and Vascular Biology, Ministry of Education, The Key Laboratory of New Drug Pharmacology and Toxicology, Shijiazhuang, China
| | - Yingzi Wang
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of Neural and Vascular Biology, Ministry of Education, The Key Laboratory of New Drug Pharmacology and Toxicology, Shijiazhuang, China
| | - Xinmeng Li
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of Neural and Vascular Biology, Ministry of Education, The Key Laboratory of New Drug Pharmacology and Toxicology, Shijiazhuang, China
| | - Yongxue Zhang
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of Neural and Vascular Biology, Ministry of Education, The Key Laboratory of New Drug Pharmacology and Toxicology, Shijiazhuang, China
| | - Xiaona Du
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of Neural and Vascular Biology, Ministry of Education, The Key Laboratory of New Drug Pharmacology and Toxicology, Shijiazhuang, China
| | - Hailin Zhang
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of Neural and Vascular Biology, Ministry of Education, The Key Laboratory of New Drug Pharmacology and Toxicology, Shijiazhuang, China
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22
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Mlinar B, Montalbano A, Waider J, Lesch KP, Corradetti R. Increased functional coupling of 5-HT 1A autoreceptors to GIRK channels in Tph2 -/- mice. Eur Neuropsychopharmacol 2017; 27:1258-1267. [PMID: 29126768 DOI: 10.1016/j.euroneuro.2017.10.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Revised: 10/14/2017] [Accepted: 10/22/2017] [Indexed: 10/18/2022]
Abstract
Firing activity of serotonergic neurons is under regulatory control by somatodendritic 5-HT1A autoreceptors (5-HT1AARs). Enhanced 5-HT1AAR functioning may cause decreased serotonergic signaling in brain and has thereby been implicated in the etiology of mood and anxiety disorders. Tryptophan hydroxylase-2 knockout (Tph2-/-) mice exhibit sensitization of 5-HT1A agonist-induced inhibition of serotonergic neuron firing and thus represents a unique animal model of enhanced 5-HT1AAR functioning. To elucidate the mechanisms underlying 5-HT1AAR supersensitivity in Tph2-/- mice, we characterized the activation of G protein-coupled inwardly-rectifying potassium (GIRK) conductance by the 5-HT1A receptor agonist 5-carboxamidotryptamine using whole-cell recordings from serotonergic neurons in dorsal raphe nucleus. Tph2-/- mice exhibited a mean twofold leftward shift of the agonist concentration-response curve (p < 0.001) whereas the maximal response, proportional to the 5-HT1AAR number, was not different (p = 0.42) compared to Tph2+/- and Tph2+/+ littermates. No differences were found in the basal inwardly-rectifying potassium conductance, determined in the absence of agonist, (p = 0.80) nor in total GIRK conductance activated by intracellular application of GTP-γ-S (p = 0.69). These findings indicate increased functional coupling of 5-HT1AARs to GIRK channels in Tph2-/- mice without a concomitant increase in 5-HT1AARs and/or GIRK channel density. In addition, no changes were found in α1-adrenergic facilitation of firing (p = 0.72) indicating lack of adaptive changes Tph2-/- mice. 5-HT1AAR supersensitivity may represents a previously unrecognized cause of serotonergic system hypofunction and associated disorders and provides a possible explanation for conflicting results on the correlation between 5-HT1AAR density and depression in clinical imaging studies.
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Affiliation(s)
- Boris Mlinar
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy.
| | - Alberto Montalbano
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Jonas Waider
- Division of Molecular Psychiatry, Laboratory of Translational Neuroscience, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany
| | - Klaus-Peter Lesch
- Division of Molecular Psychiatry, Laboratory of Translational Neuroscience, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany; Laboratory of Psychiatric Neurobiology, Institute of Molecular Medicine, I.M. Sechenov First Moscow State Medical University, Moscow, Russia; Department of Translational Neuroscience, School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Renato Corradetti
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
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Savy CY, Fitchett AE, Blain PG, Morris CM, Judge SJ. Gene expression analysis reveals chronic low level exposure to the pesticide diazinon affects psychological disorders gene sets in the adult rat. Toxicology 2017; 393:90-101. [PMID: 29108742 DOI: 10.1016/j.tox.2017.11.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/26/2017] [Accepted: 11/02/2017] [Indexed: 11/29/2022]
Abstract
Chronic low level exposure to organophosphate (OPs) pesticides in adulthood has been linked to adverse neurobehavioural deficits and psychological disorder symptoms, although this remains a contentious issue. The OP-induced biological changes that could underlie these effects are unclear. We assessed gene expression changes following chronic low level exposure to diazinon, a pesticide with a high dietary exposure risk. Adult male rats were orally exposed to diazinon (0, 1, 2mg/kg, 5days a week for 12 weeks). After 4 weeks, marble burying behaviour was lower in diazinon exposed rats than vehicle exposed rats; this difference persisted for 8 weeks. Chronic diazinon exposure did not significantly inhibit acetylcholinesterase activity, the primary mechanism of action of high level OPs. Affymetrix GeneChip® HT RG-230 PM Arrays were used for gene profiling followed by Ingenuity Pathway analysis. In the hippocampus, the most significant gene expression changes caused by OP exposure were associated with Psychological Disorders, and Cell-To-Cell Signalling and Interaction functions. Genes encoding the AMPA3 glutamate receptor, glutaminase, dopamine transporter and tyrosine hydroxylase were up-regulated, whereas the gene encoding the GABAB1 receptor was down-regulated. In the dorsal raphe nucleus, genes associated with development and the Psychological Disorders function were significantly affected, including the up-regulation of the gene encoding the α1b-adrenoceptor, the major driver of serotoninergic (5-HT) neuronal activity. These data indicate that chronic exposure to diazinon in adulthood, below the threshold to inhibit acetylcholinesterase, stimulates glutamatergic, dopaminergic and serotonergic synaptic transmission which may underlie adverse neurological outcomes.
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Affiliation(s)
- Claire Y Savy
- Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK; Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
| | - Ann E Fitchett
- Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK; Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
| | - Peter G Blain
- Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK; Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
| | - Christopher M Morris
- Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK; Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
| | - Sarah J Judge
- Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK; Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
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Treatment Associated Changes of Functional Connectivity of Midbrain/Brainstem Nuclei in Major Depressive Disorder. Sci Rep 2017; 7:8675. [PMID: 28819132 PMCID: PMC5561091 DOI: 10.1038/s41598-017-09077-5] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 07/19/2017] [Indexed: 01/04/2023] Open
Abstract
Previous functional magnetic resonance imaging (fMRI) studies demonstrated an abnormally coordinated network functioning in Major Depression Disorder (MDD) during rest. The main monoamine-producing nuclei within midbrain/brainstem are functionally integrated within these specific networks. Therefore, we aimed to investigate the resting-state functional connectivity (RSFC) of these nuclei in 45 MDD patients and differences between patients receiving two different classes of antidepressant drugs. Patients showed reduced RSFC from the ventral tegmental area (VTA) to dorsal anterior cingulate cortex (dACC) and stronger RSFC to the left amygdala and dorsolateral prefrontal cortex (DLPFC). Patients treated with antidepressants influencing noradrenergic and serotonergic neurotransmission showed different RSFC from locus coeruleus to DLPFC compared to patients treated with antidepressants influencing serotonergic neurotransmission only. In the opposite contrast patients showed stronger RSFC from dorsal raphe to posterior brain regions. Enhanced VTA-RSFC to amygdala as a central region of the salience network may indicate an over‐attribution of the affective salience to internally-oriented processes. Significant correlation between decreased VTA-dACC functional connectivity and the BDI-II somatic symptoms indicates an association with diminished volition and behavioral activation in MDD. The observed differences in the FC of the midbrain/brainstem nuclei between two classes of antidepressants suggest differential neural effects of SSRIs and SNRIs.
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Watanabe T, Ishiguro S, Aoki A, Ueda M, Hayashi Y, Akiyama K, Kato K, Shimoda K. Genetic Polymorphism of 1019C/G (rs6295) Promoter of Serotonin 1A Receptor and Catechol-O-Methyltransferase in Panic Disorder. Psychiatry Investig 2017; 14:86-92. [PMID: 28096880 PMCID: PMC5240452 DOI: 10.4306/pi.2017.14.1.86] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 01/28/2016] [Accepted: 01/28/2016] [Indexed: 01/23/2023] Open
Abstract
OBJECTIVE Family and twin studies have suggested genetic liability for panic disorder (PD) and therefore we sought to determine the role of noradrenergic and serotonergic candidate genes for susceptibility for PD in a Japanese population. METHODS In this age- and gender-matched case-control study involving 119 PD patients and 119 healthy controls, we examined the genotype distributions and allele frequencies of the serotonin transporter gene linked polymorphic region (5-HTTLPR), -1019C/G (rs6295) promoter polymorphism of the serotonin receptor 1A (5-HT1A), and catechol-O-methyltransferase (COMT) gene polymorphism (rs4680) and their association with PD. RESULTS No significant differences were evident in the allele frequencies or genotype distributions of the COMT (rs4680), 5-HTTLPR polymorphisms or the -1019C/G (rs6295) promoter polymorphism of 5-HT1A between PD patients and controls. Although there were no significant associations of these polymorphisms with in subgroups of PD patients differentiated by gender or in subgroup comorbid with agoraphobia (AP), significant difference was observed in genotype distributions of the -1019C/G (rs6295) promoter polymorphism of 5-HT1A between PD patients without AP and controls (p=0.047). CONCLUSION In this association study, the 1019C/G (rs6295) promoter polymorphism of the 5-HT1A receptor G/G genotype was associated with PD without AP in a Japanese population.
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Affiliation(s)
- Takashi Watanabe
- Department of Psychiatry, Dokkyo Medical University School of Medicine, Shimotsuga, Tochigi, Japan
| | - Shin Ishiguro
- Department of Psychiatry, Dokkyo Medical University School of Medicine, Shimotsuga, Tochigi, Japan
| | - Akiko Aoki
- Department of Psychiatry, Dokkyo Medical University School of Medicine, Shimotsuga, Tochigi, Japan
| | - Mikito Ueda
- Department of Psychiatry, Dokkyo Medical University School of Medicine, Shimotsuga, Tochigi, Japan
| | - Yuki Hayashi
- Department of Psychiatry, Dokkyo Medical University School of Medicine, Shimotsuga, Tochigi, Japan
| | - Kazufumi Akiyama
- Biological Psychiatry and Neuroscience, Dokkyo Medical University School of Medicine, Shimotsuga, Tochigi, Japan
| | - Kazuko Kato
- Sakura La Mental Clinic, Utsunomiya, Tochigi, Japan
| | - Kazutaka Shimoda
- Department of Psychiatry, Dokkyo Medical University School of Medicine, Shimotsuga, Tochigi, Japan
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The hallucinogen d -lysergic diethylamide (LSD) decreases dopamine firing activity through 5-HT 1A , D 2 and TAAR 1 receptors. Pharmacol Res 2016; 113:81-91. [DOI: 10.1016/j.phrs.2016.08.022] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 06/12/2016] [Accepted: 08/16/2016] [Indexed: 10/21/2022]
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27
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Hamed A, Daszczuk P, Kursa MB, Turzyńska D, Sobolewska A, Lehner M, Boguszewski PM, Szyndler J. Non-parametric analysis of neurochemical effects and Arc expression in amphetamine-induced 50-kHz ultrasonic vocalization. Behav Brain Res 2016; 312:174-85. [DOI: 10.1016/j.bbr.2016.05.042] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 05/16/2016] [Accepted: 05/19/2016] [Indexed: 11/30/2022]
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28
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Mlinar B, Montalbano A, Piszczek L, Gross C, Corradetti R. Firing Properties of Genetically Identified Dorsal Raphe Serotonergic Neurons in Brain Slices. Front Cell Neurosci 2016; 10:195. [PMID: 27536220 PMCID: PMC4971071 DOI: 10.3389/fncel.2016.00195] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 07/22/2016] [Indexed: 11/13/2022] Open
Abstract
Tonic spiking of serotonergic neurons establishes serotonin levels in the brain. Since the first observations, slow regular spiking has been considered as a defining feature of serotonergic neurons. Recent studies, however, have revealed the heterogeneity of serotonergic neurons at multiple levels, comprising their electrophysiological properties, suggesting the existence of functionally distinct cellular subpopulations. In order to examine in an unbiased manner whether serotonergic neurons of the dorsal raphe nucleus (DRN) are heterogeneous, we used a non-invasive loose-seal cell-attached method to record α1 adrenergic receptor-stimulated spiking of a large sample of neurons in brain slices obtained from transgenic mice lines that express fluorescent marker proteins under the control of serotonergic system-specific Tph2 and Pet-1 promoters. We found wide homogeneous distribution of firing rates, well fitted by a single Gaussian function (r (2) = 0.93) and independent of anatomical location (P = 0.45), suggesting that in terms of intrinsic firing properties, serotonergic neurons in the DRN represent a single cellular population. Characterization of the population in terms of spiking regularity was hindered by its dependence on the firing rate. For instance, the coefficient of variation of the interspike intervals (ISI), a common measure of spiking irregularity, is of limited usefulness since it correlates negatively with the firing rate (r = -0.33, P < 0.0001). Nevertheless, the majority of neurons exhibited regular, pacemaker-like activity, with coefficient of variance of the ISI lower than 0.5 in ~97% of cases. Unexpectedly, a small percentage of neurons (~1%) exhibited a particular spiking pattern, characterized by low frequency (~0.02-0.1 Hz) oscillations in the firing rate. Transitions between regular and oscillatory firing were observed, suggesting that the oscillatory firing is an alternative firing pattern of serotonergic neurons.
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Affiliation(s)
- Boris Mlinar
- Department of Neuroscience, Psychology, Drug Research and Children's Health, University of Florence Florence, Italy
| | - Alberto Montalbano
- Department of Neuroscience, Psychology, Drug Research and Children's Health, University of Florence Florence, Italy
| | - Lukasz Piszczek
- Mouse Biology Unit, European Molecular Biology Laboratory Monterotondo, Italy
| | - Cornelius Gross
- Mouse Biology Unit, European Molecular Biology Laboratory Monterotondo, Italy
| | - Renato Corradetti
- Department of Neuroscience, Psychology, Drug Research and Children's Health, University of Florence Florence, Italy
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Pharmacologic Evaluation of Antidepressant Activity and Synthesis of 2-Morpholino-5-phenyl-6H-1,3,4-thiadiazine Hydrobromide. Pharmaceuticals (Basel) 2016; 9:ph9020027. [PMID: 27213404 PMCID: PMC4932545 DOI: 10.3390/ph9020027] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 05/12/2016] [Accepted: 05/13/2016] [Indexed: 11/17/2022] Open
Abstract
Substituted thiadiazines exert a reliable therapeutic effect in treating stress, and a schematic description of their ability to influence all aspects of a stress response has been depicted. This study was conducted to pharmacologically evaluate compound L-17, a substituted thiadiazine, (2-morpholino-5-phenyl-6H-1,3,4-thiadiazine, hydrobromide) for possible anti-psychotic/antidepressant activity. Compound L-17 was synthesized by cyclocondensation of α-bromoacetophenone with the original morpholine-4-carbothionic acid hydrazide. Pharmacologic evaluations were conducted using methods described by E.F. Lavretskaya (1985), and in accordance with published guidelines for studying drugs for neuroleptic activity. Compound L-17 was evaluated for various possible mechanisms of action, including its effects on cholinergic system agonists/antagonists, dopaminergic neurotransmission, the adrenergic system, and 5-HT3 serotonin receptors. One or more of these mechanisms may be responsible for the beneficial effects shown by thiadiazine compounds in experiments conducted to evaluate their activity in models of acute stress and acute myocardial infarction.
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30
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Feenstra MGP, Klompmakers A, Figee M, Fluitman S, Vulink N, Westenberg HGM, Denys D. Prazosin addition to fluvoxamine: A preclinical study and open clinical trial in OCD. Eur Neuropsychopharmacol 2016; 26:310-319. [PMID: 26712326 DOI: 10.1016/j.euroneuro.2015.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 11/01/2015] [Accepted: 12/01/2015] [Indexed: 11/30/2022]
Abstract
The efficacy of selective serotonin reuptake inhibitors (SRIs) in psychiatric disorders may be "augmented" through the addition of atypical antipsychotic drugs. A synergistic increase in dopamine (DA) release in the prefrontal cortex has been suggested to underlie this augmentation effect, though the mechanism of action is not clear yet. We used in vivo microdialysis in rats to study DA release following the administration of combinations of fluvoxamine (10 mg/kg) and quetiapine (10 mg/kg) with various monoamine-related drugs. The results confirmed that the selective 5-HT1A antagonist WAY-100635 (0.05 mg/kg) partially blocked the fluvoxamine-quetiapine synergistic effect (maximum DA increase dropped from 325% to 214%). A novel finding is that the α1-adrenergic blocker prazosin (1 mg/kg), combined with fluvoxamine, partially mimicked the effect of augmentation (maximum DA increase 205%; area-under-the-curve 163%). As this suggested that prazosin augmentation might be tested in a clinical study, we performed an open clinical trial of prazosin 20 mg addition to SRI in therapy-resistant patients with obsessive-compulsive disorder applying for neurosurgery. A small, non-significant reduction in Yale Brown Obsessive Compulsive Scale (Y-BOCS) scores was observed in 10 patients and one patient was classified as a responder with a reduction in Y-BOCS scores of more than 25%. We suggest that future clinical studies augmenting SRIs with an α1-adrenergic blocker in less treatment resistant cases should be considered. The clinical trial "Prazosin in combination with a serotonin reuptake inhibitor for patients with Obsessive Compulsive disorder: an open label study" was registered at 24/05/2011 under trial number ISRCTN61562706: http://www.controlled-trials.com/ISRCTN61562706.
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Affiliation(s)
- Matthijs G P Feenstra
- Department of Psychiatry, Academic Medical Center, University of Amsterdam, The Netherlands; Netherlands Institute for Neuroscience, an institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - André Klompmakers
- Department of Psychiatry, Academic Medical Center, University of Amsterdam, The Netherlands; Netherlands Institute for Neuroscience, an institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Martijn Figee
- Department of Psychiatry, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Sjoerd Fluitman
- Department of Psychiatry, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Nienke Vulink
- Department of Psychiatry, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Herman G M Westenberg
- Department of Psychiatry, UMC Utrecht, Rudolf Magnus Institute of Neuroscience, The Netherlands
| | - Damiaan Denys
- Department of Psychiatry, Academic Medical Center, University of Amsterdam, The Netherlands; Netherlands Institute for Neuroscience, an institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands.
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31
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Judge SJ, Savy CY, Campbell M, Dodds R, Gomes LK, Laws G, Watson A, Blain PG, Morris CM, Gartside SE. Mechanism for the acute effects of organophosphate pesticides on the adult 5-HT system. Chem Biol Interact 2015; 245:82-9. [PMID: 26721196 PMCID: PMC4732990 DOI: 10.1016/j.cbi.2015.12.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 12/03/2015] [Accepted: 12/18/2015] [Indexed: 11/07/2022]
Abstract
The neurotransmitter serotonin (5-HT) is involved in mood disorder aetiology and it has been reported that (organophosphate) OP exposure affects 5-HT turnover. The aim of this study was to elucidate the mechanism underlying OP effects on the adult 5-HT system. First, acute in vivo administration of the OP diazinon (0, 1.3, 13 or 39 mg/kg i.p.) to male Hooded Lister rats inhibited the activity of the cholinergic enzyme acetylcholinesterase in blood and in the hippocampus, dorsal raphe nucleus (DRN), striatum and prefrontal cortex. Diazinon-induced cholinesterase inhibition was greatest in the DRN, the brain's major source of 5-HT neurones. Second, acute in vivo diazinon exposure (0 or 39 mg/kg i.p.) increased the basal firing rate of DRN neurones measured ex vivo in brain slices. The excitatory responses of DRN neurones to α1-adrenoceptor or AMPA/kainate receptor activation were not affected by in vivo diazinon exposure but the inhibitory response to 5-HT was attenuated, indicating 5-HT1A autoreceptor down-regulation. Finally, direct application of the diazinon metabolite diazinon oxon to naive rat brain slices increased the firing rate of DRN 5-HT neurones, as did chlorpyrifos-oxon, indicating the effect was not unique to diazinon. The oxon-induced augmentation of firing was blocked by the nicotinic acetylcholine receptor antagonist mecamylamine and the AMPA/kainate glutamate receptor antagonist DNQX. Together these data indicate that 1) acute OP exposure inhibits DRN cholinesterase, leading to acetylcholine accumulation, 2) the acetylcholine activates nicotinic receptors on 5-HT neurones and also on glutamatergic neurones, thus releasing glutamate and activating 5-HT neuronal AMPA/kainate receptors 3) the increase in 5-HT neuronal activity, and resulting 5-HT release, may lead to 5-HT1A autoreceptor down-regulation. This mechanism may be involved in the reported increase in risk of developing anxiety and depression following occupational OP exposure. Organophosphate exposure inhibits dorsal raphe nucleus cholinesterase activity. Organophosphate oxon exposure activates 5-HT neurones in the dorsal raphe nucleus. Nicotinic and AMPA receptors mediate the oxon-induced activation of 5-HT neurones. Organophosphate exposure attenuates the response to 5-HT1A autoreceptor activation.
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Affiliation(s)
- Sarah J Judge
- Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK; Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
| | - Claire Y Savy
- Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK; Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Matthew Campbell
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Rebecca Dodds
- Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK; Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Larissa Kruger Gomes
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Grace Laws
- Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK; Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Anna Watson
- Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK; Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Peter G Blain
- Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK; Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Christopher M Morris
- Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK; Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Sarah E Gartside
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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32
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The antidepressant mechanism of action of vagus nerve stimulation: Evidence from preclinical studies. Neurosci Biobehav Rev 2015; 56:26-34. [DOI: 10.1016/j.neubiorev.2015.06.019] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 06/19/2015] [Accepted: 06/21/2015] [Indexed: 01/22/2023]
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33
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Andrade R, Huereca D, Lyons JG, Andrade EM, McGregor KM. 5-HT1A Receptor-Mediated Autoinhibition and the Control of Serotonergic Cell Firing. ACS Chem Neurosci 2015; 6:1110-5. [PMID: 25913021 DOI: 10.1021/acschemneuro.5b00034] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The idea that serotonergic synaptic transmission plays an essential role in the control of mood and the pharmacotherapy of anxiety and depression is one of the cornerstones of modern biological psychiatry. As a result, there is intense interest in understanding the mechanisms controlling the activity of serotonin-synthesizing (serotonergic) neurons. One of the oldest and most durable ideas emerging from this work is that serotonergic neurons are capable of autonomously regulating their own basal firing rate. Serotonergic neurons express on their surface 5-HT1A receptors (autoreceptors) that, when activated, induce the opening of potassium channels that hyperpolarize and thereby inhibit cell firing. Activity-dependent release of serotonin within serotonergic nuclei is thought to activate these autoreceptors, thus completing an autoinhibitory feedback loop. This concept, which was originally proposed in the 1970s, has proven to be enormously fruitful and has guided the interpretation of a broad range of clinical and preclinical work. Yet, remarkably, electrophysiological studies seeking to directly demonstrate this phenomenon, especially in in vitro brain slices, have produced mixed results. Here, we critically review this work with a focus on electrophysiological studies, which directly assess neuronal activity. We also highlight recent work suggesting that 5-HT1A receptor-mediated autoinhibition may play other roles in the control of firing besides acting as a feedback regulator for the pacemaker-like firing rate of serotonergic neurons.
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Affiliation(s)
- Rodrigo Andrade
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan 48201, United States
| | - Daniel Huereca
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan 48201, United States
| | - Joseph G. Lyons
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan 48201, United States
| | - Elaine M. Andrade
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan 48201, United States
| | - Kelly M. McGregor
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan 48201, United States
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Weber T, Vogt MA, Gartside SE, Berger SM, Lujan R, Lau T, Herrmann E, Sprengel R, Bartsch D, Gass P. Adult AMPA GLUA1 receptor subunit loss in 5-HT neurons results in a specific anxiety-phenotype with evidence for dysregulation of 5-HT neuronal activity. Neuropsychopharmacology 2015; 40:1471-84. [PMID: 25547714 PMCID: PMC4397405 DOI: 10.1038/npp.2014.332] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 12/12/2014] [Accepted: 12/15/2014] [Indexed: 12/25/2022]
Abstract
Both the glutamatergic and serotonergic (5-HT) systems are implicated in the modulation of mood and anxiety. Descending cortical glutamatergic neurons regulate 5-HT neuronal activity in the midbrain raphe nuclei through α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors. To analyze the functional role of GLUA1-containing AMPA receptors in serotonergic neurons, we used the Cre-ERT2/loxP-system for the conditional inactivation of the GLUA1-encoding Gria1 gene selectively in 5-HT neurons of adult mice. These Gria1(5-HT-/-) mice exhibited a distinct anxiety phenotype but showed no alterations in locomotion, depression-like behavior, or learning and memory. Increased anxiety-related behavior was associated with significant decreases in tryptophan hydroxylase 2 (TPH2) expression and activity, and subsequent reductions in tissue levels of 5-HT, its metabolite 5-hydroxyindoleacetic acid (5-HIAA), and norepinephrine in the raphe nuclei. However, TPH2 expression and activity as well as monoamine levels were unchanged in the projection areas of 5-HT neurons. Extracellular electrophysiological recordings of 5-HT neurons revealed that, while α1-adrenoceptor-mediated excitation was unchanged, excitatory responses to AMPA were enhanced and the 5-HT1A autoreceptor-mediated inhibitory response to 5-HT was attenuated in Gria1(5-HT-/-) mice. Our data show that a loss of GLUA1 protein in 5-HT neurons enhances AMPA receptor function and leads to multiple local molecular and neurochemical changes in the raphe nuclei that dysregulate 5-HT neuronal activity and induce anxiety-like behavior.
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Affiliation(s)
- Tillmann Weber
- Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany,Department of Molecular Biology, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany,AHG Klinik Wilhelmsheim, 71570 Oppenweiler, Germany. Tel: +49 0 7193 52215, Fax: +49 0 7193 52245, E-mail:
| | - Miriam A Vogt
- Research Group Animal Models in Psychiatry, Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
| | - Sarah E Gartside
- Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Stefan M Berger
- Department of Molecular Biology, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
| | - Rafael Lujan
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, Albacete, Spain
| | - Thorsten Lau
- Biochemical Laboratory, Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/HeidelbergUniversity, Mannheim, Germany
| | - Elke Herrmann
- Department of Molecular Biology, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
| | - Rolf Sprengel
- Department of Molecular Neurobiology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Dusan Bartsch
- Department of Molecular Biology, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
| | - Peter Gass
- Research Group Animal Models in Psychiatry, Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
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Ostock CY, Hallmark J, Palumbo N, Bhide N, Conti M, George JA, Bishop C. Modulation of L-DOPA's antiparkinsonian and dyskinetic effects by α2-noradrenergic receptors within the locus coeruleus. Neuropharmacology 2015; 95:215-25. [PMID: 25817388 DOI: 10.1016/j.neuropharm.2015.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 02/12/2015] [Accepted: 03/09/2015] [Indexed: 01/01/2023]
Abstract
Long-term l-DOPA use for Parkinson's disease (PD) is frequently complicated by the emergence of a debilitating motor side effect known as l-DOPA-induced dyskinesia (LID). Accumulating evidence has implicated the norepinephrine (NE) system in the pathogenesis of LID. Here we used the unilateral 6-hydroxydopamine rat model of PD to determine the role of the α2-adrenoceptors (α2R) in l-DOPA's therapeutic and detrimental motor-inducing effects. First, we characterized the effects of systemic α2R stimulation with clonidine, or blockade with atipamezole, on LID using the rodent abnormal involuntary movements scale, and l-DOPA's therapeutic effects using the forepaw adjusting steps test and locomotor activity chambers. The anatomical locus of action of α2R in LID was investigated by directly infusing clonidine or atipamezole into the locus coeruleus prior to systemic l-DOPA administration. Results showed systemic clonidine treatment reduced LID and locomotor activity but did not interfere with l-DOPA's antiparkinsonian benefits. Conversely, systemic atipamezole pretreatment prolonged LID and locomotor activity but did not modulate l-DOPA's antiparkinsonian benefits. Intra-LC infusions of clonidine and atipamezole mirrored systemic effects where clonidine reduced, and atipamezole increased, LID. Collectively, these results demonstrate that α2R play an important modulatory role in l-DOPA-mediated behaviors and should be further investigated as a potential therapeutic target.
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Affiliation(s)
- Corinne Y Ostock
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Joy Hallmark
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Noel Palumbo
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Nirmal Bhide
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Melissa Conti
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Jessica A George
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Christopher Bishop
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA.
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Guiard BP, Di Giovanni G. Central serotonin-2A (5-HT2A) receptor dysfunction in depression and epilepsy: the missing link? Front Pharmacol 2015; 6:46. [PMID: 25852551 PMCID: PMC4362472 DOI: 10.3389/fphar.2015.00046] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 02/24/2015] [Indexed: 11/17/2022] Open
Abstract
5-Hydroxytryptamine 2A receptors (5-HT2A-Rs) are G-protein coupled receptors. In agreement with their location in the brain, they have been implicated not only in various central physiological functions including memory, sleep, nociception, eating and reward behaviors, but also in many neuropsychiatric disorders. Interestingly, a bidirectional link between depression and epilepsy is suspected since patients with depression and especially suicide attempters have an increased seizure risk, while a significant percentage of epileptic patients suffer from depression. Such epidemiological data led us to hypothesize that both pathologies may share common anatomical and neurobiological alteration of the 5-HT2A signaling. After a brief presentation of the pharmacological properties of the 5-HT2A-Rs, this review illustrates how these receptors may directly or indirectly control neuronal excitability in most networks involved in depression and epilepsy through interactions with the monoaminergic, GABAergic and glutamatergic neurotransmissions. It also synthetizes the preclinical and clinical evidence demonstrating the role of these receptors in antidepressant and antiepileptic responses.
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Affiliation(s)
- Bruno P Guiard
- CNRS, Centre de Recherches sur la Cognition Animale, UMR 5169, Toulouse France ; CNRS, Centre de Recherches sur la Cognition Animale Université de Toulouse 3, UMR 5169, Toulouse, France ; INSERM U1178 Team ≪Depression and Antidepressants≫ Faculté de Pharmacie Paris Sud, Châtenay-Malabry, France
| | - Giuseppe Di Giovanni
- Neurophysiology Unit, Laboratory for the Study of Neurological Disorders, Department of Physiology and Biochemistry, University of Malta, Msida Malta ; School of Biosciences, University of Cardiff, Cardiff UK
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Cohen JY, Amoroso MW, Uchida N. Serotonergic neurons signal reward and punishment on multiple timescales. eLife 2015; 4. [PMID: 25714923 PMCID: PMC4389268 DOI: 10.7554/elife.06346] [Citation(s) in RCA: 229] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 02/24/2015] [Indexed: 11/30/2022] Open
Abstract
Serotonin's function in the brain is unclear. One challenge in testing the numerous hypotheses about serotonin's function has been observing the activity of identified serotonergic neurons in animals engaged in behavioral tasks. We recorded the activity of dorsal raphe neurons while mice experienced a task in which rewards and punishments varied across blocks of trials. We ‘tagged’ serotonergic neurons with the light-sensitive protein channelrhodopsin-2 and identified them based on their responses to light. We found three main features of serotonergic neuron activity: (1) a large fraction of serotonergic neurons modulated their tonic firing rates over the course of minutes during reward vs punishment blocks; (2) most were phasically excited by punishments; and (3) a subset was phasically excited by reward-predicting cues. By contrast, dopaminergic neurons did not show firing rate changes across blocks of trials. These results suggest that serotonergic neurons signal information about reward and punishment on multiple timescales. DOI:http://dx.doi.org/10.7554/eLife.06346.001 Rewards and punishments can both encourage animals to change their immediate behavior and influence their mood over a longer term, particularly when given repeatedly. A region of the brain that increases its activity in response to rewards and punishments also contains many neurons that communicate with each other by releasing a chemical called serotonin. This chemical is commonly thought to produce feelings of happiness; however, it remains unclear exactly how these particular ‘serotonergic’ neurons help to process rewards and punishments. The ideal way to work out the role that a type of neuron plays in a behavior is to measure its electrical activity as the behavior is being performed. However, it is difficult to distinguish the activity of serotonergic neurons from the activity of the non-serotonergic neurons around them. To overcome this problem, Cohen et al. used viruses to force serotonergic neurons to make a type of ion channel that produces electrical currents in response to light. Shining light on these neurons via optical fibers and then measuring the neurons' responses helped to develop criteria that can identify which responses are generated by the serotonergic neurons. Cohen et al. then recorded the activity of serotonergic neurons in thirsty mice as they experienced a series of rewards (for example, a drop of water) or punishments (such as a puff of air to the eye). Each reward or punishment was preceded by a distinct odor, so that the mice learned to anticipate what was coming. These experiments revealed that serotonergic neurons respond to rewards and punishments by changing two aspects of their electrical activity: by producing short bursts of high activity, and by altering their baseline activity. Some of the serotonergic neurons fired rapidly in response to punishments, but not rewards; others fired rapidly when the mice detected a scent that meant that a reward was about to be given. The average level of reward or punishment the mice received also affected the baseline activity of many of the serotonergic neurons; this effect lasted for several minutes. Overall, Cohen et al. suggest that serotonergic neurons can affect how mice respond to rewards or punishments in both the short and long term. Future experiments should aim to understand the diversity of the signals that Cohen et al. observed, and to determine how these signals are used to drive behavior. Ultimately, understanding how neural circuits made up of different types of cells work may aid in understanding the neural basis of behavior. DOI:http://dx.doi.org/10.7554/eLife.06346.002
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Affiliation(s)
- Jeremiah Y Cohen
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, United States
| | - Mackenzie W Amoroso
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, United States
| | - Naoshige Uchida
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, United States
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Abstract
Impulsivity, risk-taking behavior, and elevated stress responsivity are prominent symptoms of mania, a behavioral state common to schizophrenia and bipolar disorder. Though inflammatory processes activated within the brain are involved in the pathophysiology of both disorders, the specific mechanisms by which neuroinflammation drives manic behavior are not well understood. Serotonin cell bodies originating within the dorsal raphe (DR) play a major role in the regulation of behavioral features characteristic of mania. Therefore, we hypothesized that the link between neuroinflammation and manic behavior may be mediated by actions on serotonergic neurocircuitry. To examine this, we induced local neuroinflammation in the DR by viral delivery of Cre recombinase into interleukin (IL)-1β(XAT) transgenic male and female mice, resulting in overexpressing of the proinflammatory cytokine, IL-1β. For assertion of brain-region specificity of these outcomes, the prefrontal cortex (PFC), as a downstream target of DR serotonergic projections, was also infused. Inflammation within the DR, but not the PFC, resulted in a profound display of manic-like behavior, characterized by increased stress-induced locomotion and responsivity, and reduced risk-aversion/fearfulness. Microarray analysis of the DR revealed a dramatic increase in immune-related genes, and dysregulation of genes important in GABAergic, glutamatergic, and serotonergic neurotransmission. Behavioral and physiological changes were driven by a loss of serotonergic neurons and reduced output as measured by high-performance liquid chromatography, demonstrating inflammation-induced serotonergic hypofunction. Behavioral changes were rescued by acute selective serotonin reuptake inhibitor treatment, supporting the hypothesis that serotonin dysregulation stemming from neuroinflammation in the DR underlies manic-like behaviors.
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Bruzos-Cidón C, Miguelez C, Rodríguez JJ, Gutiérrez-Lanza R, Ugedo L, Torrecilla M. Altered neuronal activity and differential sensitivity to acute antidepressants of locus coeruleus and dorsal raphe nucleus in Wistar Kyoto rats: a comparative study with Sprague Dawley and Wistar rats. Eur Neuropsychopharmacol 2014; 24:1112-22. [PMID: 24582527 DOI: 10.1016/j.euroneuro.2014.02.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 01/24/2014] [Accepted: 02/12/2014] [Indexed: 12/27/2022]
Abstract
The Wistar Kyoto rat (WKY) has been proposed as an animal model of depression. The noradrenergic nucleus, locus coeruleus (LC) and the serotonergic nucleus, dorsal raphe (DRN) have been widely implicated in the ethiopathology of this disease. Thus, the goal of the present study was to investigate in vivo the electrophysiological properties of LC and DRN neurons from WKY rats, using single-unit extracellular techniques. Wistar (Wis) and Sprague Dawley (SD) rats were used as control strains. In the LC from WKY rats the basal firing rate was higher than that obtained in the Wis and SD strain, and burst firing activity also was greater compared to that in Wis strain but not in SD. The sensitivity of LC neurons to the inhibitory effect of the α2-adrenoceptor agonist, clonidine and the antidepressant reboxetine was lower in WKY rats compared to Wis, but not SD. Regarding DRN neurons, in WKY rats burst activity was lower than that obtained in Wis and SD rats, although no differences were observed in other firing parameters. Interestingly, while the sensitivity of DRN neurons to the inhibitory effect of the 5-HT1A receptor agonist, 8-OH-DPAT was lower in the WKY strain, the antidepressant fluoxetine had a greater inhibitory potency in this rat strain compared to that recorded in the Wis group. Overall, these results point out important electrophysiological differences regarding noradrenergic and serotonergic systems between Wis and WKY rats, supporting the utility of the WKY rat as an important tool in the research of cellular basis of depression.
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Affiliation(s)
- C Bruzos-Cidón
- Department of Pharmacology, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, 48940 Leioa, Spain
| | - C Miguelez
- Department of Pharmacology, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, 48940 Leioa, Spain; Department of Pharmacology, School of Pharmacy, University of the Basque Country UPV/EHU, 01006 Vitoria-Gasteiz, Spain
| | - J J Rodríguez
- Department of Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, 48940 Leioa, Spain
| | - R Gutiérrez-Lanza
- Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, 48940 Leioa, Spain
| | - L Ugedo
- Department of Pharmacology, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, 48940 Leioa, Spain
| | - M Torrecilla
- Department of Pharmacology, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, 48940 Leioa, Spain.
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Repeated exposure to MDMA triggers long-term plasticity of noradrenergic and serotonergic neurons. Mol Psychiatry 2014; 19:823-33. [PMID: 23958955 DOI: 10.1038/mp.2013.97] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 06/28/2013] [Accepted: 07/10/2013] [Indexed: 11/08/2022]
Abstract
3,4-Methylenedioxymethamphetamine (MDMA or 'ecstasy') is a psychostimulant drug, widely used recreationally among young people in Europe and North America. Although its neurotoxicity has been extensively described, little is known about its ability to strengthen neural circuits when administered in a manner that reproduces human abuse (i.e. repeated exposure to a low dose). C57BL/6J mice were repeatedly injected with MDMA (10 mg kg(-1), intraperitoneally) and studied after a 4-day or a 1-month withdrawal. We show, using in vivo microdialysis and locomotor activity monitoring, that repeated injections of MDMA induce a long-term sensitization of noradrenergic and serotonergic neurons, which correlates with behavioral sensitization. The development of this phenomenon, which lasts for at least 1 month after withdrawal, requires repeated stimulation of α(1B)-adrenergic and 5-hydroxytryptamine (5-HT)(2A) receptors. Moreover, behavioral and neuroendocrine assays indicate that hyper-reactivity of noradrenergic and serotonergic networks is associated with a persistent desensitization of somatodendritic α(2A)-adrenergic and 5-HT1A autoreceptor function. Finally, molecular analysis including radiolabeling, western blot and quantitative reverse transcription-polymerase chain reaction reveals that mice repeatedly treated with MDMA exhibit normal α(2A)-adrenergic and 5-HT(1A) receptor binding, but a long-lasting downregulation of Gαi proteins expression in both locus coeruleus and dorsal raphe nucleus. Altogether, our results show that repeated MDMA exposure causes strong neural and behavioral adaptations and that inhibitory feedback mediated by α(2A)-adrenergic and 5-HT(1A) autoreceptors has an important role in the physiopathology of addictive behaviors.
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Kamińska K, Gołembiowska K, Rogóż Z. The effect of risperidone on the mirtazapine-induced changes in extracellular monoamines in the rat frontal cortex. Pharmacol Rep 2014; 66:984-90. [PMID: 25443725 DOI: 10.1016/j.pharep.2014.06.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 05/21/2014] [Accepted: 06/05/2014] [Indexed: 11/25/2022]
Abstract
BACKGROUND The aim of our study was to understand the mechanism of clinical efficacy of the combination of an antidepressant and risperidone in drug-resistant depression. METHODS We studied the effect of an antidepressant (mirtazapine) and risperidone (atypical antipsychotic), given separately or jointly on extracellular levels of dopamine (DA), serotonin (5-HT) and noradrenaline (NA) in the rat frontal cortex. The animals were given a single intraperitoneal injection of risperidone (1mg/kg) and mirtazapine (10 and 20mg/kg). The release of monoamines in the rat frontal cortex was investigated using a microdialysis in freely moving animals, and monoamine levels were assayed by HPLC with coulochemical detection. RESULTS Risperidone increased the cortical extracellular levels of DA, 5-HT and NA. Similarly, mirtazapine dose-dependently increased the cortical extracellular levels of the monoamines studied. A combination of mirtazapine either at the higher dose (20mg/kg) or at both doses (10 and 20mg/kg) with risperidone produced a significant effect on DA and NA release, respectively compared to the effect of any drug given alone. The increase in the DA (but not NA) release induced by mirtazapine plus risperidone was partly blocked by the selective 5-HT1A antagonist WAY 100635 (0.2mg/kg). CONCLUSIONS Our data indicate that the increase of cortical extracellular levels of DA and NA by combined administration of mirtazapine and risperidone may be of crucial importance to the pharmacotherapy of drug resistant depression, and that, among other mechanisms, 5-HT1A, 5-HT2A, α2-adrenergic and histamine H1 receptors may play some role in this effect.
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Affiliation(s)
- Katarzyna Kamińska
- Department of Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Krystyna Gołembiowska
- Department of Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Zofia Rogóż
- Department of Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland.
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Tuckwell HC, Penington NJ. Computational modeling of spike generation in serotonergic neurons of the dorsal raphe nucleus. Prog Neurobiol 2014; 118:59-101. [PMID: 24784445 DOI: 10.1016/j.pneurobio.2014.04.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 04/14/2014] [Accepted: 04/21/2014] [Indexed: 01/14/2023]
Abstract
Serotonergic neurons of the dorsal raphe nucleus, with their extensive innervation of limbic and higher brain regions and interactions with the endocrine system have important modulatory or regulatory effects on many cognitive, emotional and physiological processes. They have been strongly implicated in responses to stress and in the occurrence of major depressive disorder and other psychiatric disorders. In order to quantify some of these effects, detailed mathematical models of the activity of such cells are required which describe their complex neurochemistry and neurophysiology. We consider here a single-compartment model of these neurons which is capable of describing many of the known features of spike generation, particularly the slow rhythmic pacemaking activity often observed in these cells in a variety of species. Included in the model are 11 kinds of ion channels: a fast sodium current INa, a delayed rectifier potassium current IKDR, a transient potassium current IA, a slow non-inactivating potassium current IM, a low-threshold calcium current IT, two high threshold calcium currents IL and IN, small and large conductance potassium currents ISK and IBK, a hyperpolarization-activated cation current IH and a leak current ILeak. In Sections 3-8, each current type is considered in detail and parameters estimated from voltage clamp data where possible. Three kinds of model are considered for the BK current and two for the leak current. Intracellular calcium ion concentration Cai is an additional component and calcium dynamics along with buffering and pumping is discussed in Section 9. The remainder of the article contains descriptions of computed solutions which reveal both spontaneous and driven spiking with several parameter sets. Attention is focused on the properties usually associated with these neurons, particularly long duration of action potential, steep upslope on the leading edge of spikes, pacemaker-like spiking, long-lasting afterhyperpolarization and the ramp-like return to threshold after a spike. In some cases the membrane potential trajectories display doublets or have humps or notches as have been reported in some experimental studies. The computed time courses of IA and IT during the interspike interval support the generally held view of a competition between them in influencing the frequency of spiking. Spontaneous activity was facilitated by the presence of IH which has been found in these neurons by some investigators. For reasonable sets of parameters spike frequencies between about 0.6Hz and 1.2Hz are obtained, but frequencies as high as 6Hz could be obtained with special parameter choices. Topics investigated and compared with experiment include shoulders, notches, anodal break phenomena, the effects of noradrenergic input, frequency versus current curves, depolarization block, effects of cell size and the effects of IM. The inhibitory effects of activating 5-HT1A autoreceptors are also investigated. There is a considerable discussion of in vitro versus in vivo firing behavior, with focus on the roles of noradrenergic input, corticotropin-releasing factor and orexinergic inputs. Location of cells within the nucleus is probably a major factor, along with the state of the animal.
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Affiliation(s)
- Henry C Tuckwell
- Max Planck Institute for Mathematics in the Sciences, Inselstr. 22, 04103 Leipzig, Germany; School of Electrical and Electronic Engineering, University of Adelaide, Adelaide, South Australia 5005, Australia.
| | - Nicholas J Penington
- Department of Physiology and Pharmacology, State University of New York, Downstate Medical Center, Box 29, 450 Clarkson Avenue, Brooklyn, NY 11203-2098, USA; Program in Neural and Behavioral Science and Robert F. Furchgott Center for Neural and Behavioral Science, State University of New York, Downstate Medical Center, Box 29, 450 Clarkson Avenue, Brooklyn, NY 11203-2098, USA
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Chronic nandrolone decanoate exposure during adolescence affects emotional behavior and monoaminergic neurotransmission in adulthood. Neuropharmacology 2014; 83:79-88. [PMID: 24721625 DOI: 10.1016/j.neuropharm.2014.03.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 03/25/2014] [Accepted: 03/30/2014] [Indexed: 12/14/2022]
Abstract
Nandrolone decanoate, an anabolic androgen steroid (AAS) illicitly used by adult and adolescent athletes to enhance physical performance and body image, induces psychiatric side effects, such as aggression, depression as well as a spectrum of adverse physiological impairments. Since adolescence represents a neurodevelopmental window that is extremely sensitive to the detrimental effects of drug abuse, we investigated the long-term behavioral and neurophysiological consequences of nandrolone abuse during adolescence. Adolescent rats received daily injections of nandrolone decanoate (15 mg/kg, i.m.) for 14 days (PND 40-53). At early adulthood (PND 68), forced swim, sucrose preference, open field and elevated plus maze tests were performed to assess behavioral changes. In vivo electrophysiological recordings were carried out to monitor changes in electrical activity of serotonergic neurons of the dorsal raphe nucleus (DRN) and noradrenergic neurons of the locus coeruleus (LC). Our results show that after early exposure to nandrolone, rats display depression-related behavior, characterized by increased immobility in the forced swim test and reduced sucrose intake in the sucrose preference test. In addition, adult rats presented anxiety-like behavior characterized by decreased time and number of entries in the central zone of the open field and decreased time spent in the open arms of the elevated plus maze. Nandrolone decreased the firing rate of spontaneously active serotonergic neurons in the DRN while increasing the firing rate of noradrenergic neurons in the LC. These results provide evidence that nandrolone decanoate exposure during adolescence alters the emotional profile of animals in adulthood and significantly modifies both serotonergic and noradrenergic neurotransmission.
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Yang C, Brown RE. The cholinergic agonist carbachol increases the frequency of spontaneous GABAergic synaptic currents in dorsal raphe serotonergic neurons in the mouse. Neuroscience 2013; 258:62-73. [PMID: 24231737 DOI: 10.1016/j.neuroscience.2013.11.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 10/31/2013] [Accepted: 11/02/2013] [Indexed: 12/18/2022]
Abstract
Dorsal raphe nucleus (DRN) serotonin (5-HT) neurons play an important role in feeding, mood control and stress responses. One important feature of their activity across the sleep-wake cycle is their reduced firing during rapid-eye-movement (REM) sleep which stands in stark contrast to the wake/REM-on discharge pattern of brainstem cholinergic neurons. A prominent model of REM sleep control posits a reciprocal interaction between these cell groups. 5-HT inhibits cholinergic neurons, and activation of nicotinic receptors can excite DRN 5-HT neurons but the cholinergic effect on inhibitory inputs is incompletely understood. Here, in vitro, in DRN brain slices prepared from GAD67-GFP knock-in mice, a brief (3 min) bath application of carbachol (50 μM) increased the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) in GFP-negative, putative 5-HT neurons but did not affect miniature (tetrodotoxin-insensitive) IPSCs. Carbachol had no direct postsynaptic effect. Thus, carbachol likely increases the activity of local GABAergic neurons which synapse on 5-HT neurons. Removal of dorsal regions of the slice including the ventrolateral periaqueductal gray (vlPAG) region where GABAergic neurons projecting to the DRN have been identified, abolished the effect of carbachol on sIPSCs whereas the removal of ventral regions containing the oral region of the pontine reticular nucleus (PnO) did not. In addition, carbachol directly excited GFP-positive, GABAergic vlPAG neurons. Antagonism of both muscarinic and nicotinic receptors completely abolished the effects of carbachol. We suggest cholinergic neurons inhibit DRN 5-HT neurons when acetylcholine levels are lower i.e. during quiet wakefulness and the beginning of REM sleep periods, in part via excitation of muscarinic and nicotinic receptors located on local vlPAG and DRN GABAergic neurons. Higher firing rates or burst firing of cholinergic neurons associated with attentive wakefulness or phasic REM sleep periods leads to excitation of 5-HT neurons via the activation of nicotinic receptors located postsynaptically and presynaptically on excitatory afferents.
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Affiliation(s)
- C Yang
- Laboratory of Neuroscience, Department of Psychiatry, VA Boston Healthcare System and Harvard Medical School, Brockton, MA, USA
| | - R E Brown
- Laboratory of Neuroscience, Department of Psychiatry, VA Boston Healthcare System and Harvard Medical School, Brockton, MA, USA.
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Electrophysiological perspectives on locus coeruleus: Its role in cognitive versus vegetative functions. ACTA ACUST UNITED AC 2013. [DOI: 10.3758/bf03326518] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
Numerous studies link decreased serotonin metabolites with increased impulsive and aggressive traits. However, although pharmacological depletion of serotonin is associated with increased aggression, interventions aimed at directly decreasing serotonin neuron activity have supported the opposite association. Furthermore, it is not clear if altered serotonin activity during development may contribute to some of the observed associations. Here, we used two pharmacogenetic approaches in transgenic mice to selectively and reversibly reduce the firing of serotonin neurons in behaving animals. Conditional overexpression of the serotonin 1A receptor (Htr1a) in serotonin neurons showed that a chronic reduction in serotonin neuron firing was associated with heightened aggression. Overexpression of Htr1a in adulthood, but not during development, was sufficient to increase aggression. Rapid suppression of serotonin neuron firing by agonist treatment of mice expressing Htr1a exclusively in serotonin neurons also led to increased aggression. These data confirm a role of serotonin activity in setting thresholds for aggressive behavior and support a direct association between low levels of serotonin homeostasis and increased aggression.
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l-DOPA modifies the antidepressant-like effects of reboxetine and fluoxetine in rats. Neuropharmacology 2013; 67:349-58. [DOI: 10.1016/j.neuropharm.2012.11.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2012] [Revised: 11/07/2012] [Accepted: 11/11/2012] [Indexed: 01/06/2023]
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Electrophysiological and neurochemical effects of long-term vagus nerve stimulation on the rat monoaminergic systems. Int J Neuropsychopharmacol 2013; 16:459-70. [PMID: 22717062 DOI: 10.1017/s1461145712000387] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Vagus nerve stimulation (VNS) is an adjunctive treatment for resistant epilepsy and depression. Electrophysiological recordings in the rat brain have already shown that chronic VNS increases norepinephrine (NE) neuronal firing activity and, subsequently, that of serotonin (5-HT) neurons through an activation of their excitatory α1-adrenoceptors. Long-term VNS was shown to increase the tonic activation of post-synaptic 5-HT1A receptors in the hippocampus. This study was aimed at examining the effect of VNS on extracellular 5-HT, NE and dopamine (DA) levels in different brain areas using in vivo microdialysis, on NE transmission in the hippocampus, and DA neuronal firing activity using electrophysiology. Rats were implanted with a VNS device and stimulated for 14 d with standard parameters used in treatment-resistant depression (0.25 mA, 20 Hz, 500 μs, 30 s on-5 min off). The results of the present study revealed that 2-wk VNS significantly increased extracellular NE levels in the prefrontal cortex and the hippocampus and enhanced the tonic activation of post-synaptic α2-adrenoceptors on pyramidal neurons. The electrophysiological experiments revealed a significant decrease in ventral tegmental area DA neuronal firing rate after long-term VNS; extracellular DA levels were nevertheless increased in the prefrontal cortex and nucleus accumbens. Chronic VNS significantly increased extracellular 5-HT levels in the dorsal raphe but not in the hippocampus and prefrontal cortex. In conclusion, the effect of VNS in increasing the transmission of monoaminergic systems targeted in the treatment of resistant depression should be involved, at least in part, in its antidepressant properties observed in patients not responding to many antidepressant strategies.
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Quesseveur G, Repérant C, David DJ, Gardier AM, Sanchez C, Guiard BP. 5-HT2A receptor inactivation potentiates the acute antidepressant-like activity of escitalopram: involvement of the noradrenergic system. Exp Brain Res 2013; 226:285-95. [DOI: 10.1007/s00221-013-3434-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 01/25/2013] [Indexed: 11/30/2022]
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Tuckwell HC. Biophysical properties and computational modeling of calcium spikes in serotonergic neurons of the dorsal raphe nucleus. Biosystems 2013; 112:204-13. [PMID: 23391700 DOI: 10.1016/j.biosystems.2013.01.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 01/18/2013] [Accepted: 01/18/2013] [Indexed: 11/17/2022]
Abstract
Serotonergic neurons of the dorsal raphe nuclei, with their extensive innervation of nearly the whole brain have important modulatory effects on many cognitive and physiological processes. They play important roles in clinical depression and other psychiatric disorders. In order to quantify the effects of serotonergic transmission on target cells it is desirable to construct computational models and to this end these it is necessary to have details of the biophysical and spike properties of the serotonergic neurons. Here several basic properties are reviewed with data from several studies since the 1960s to the present. The quantities included are input resistance, resting membrane potential, membrane time constant, firing rate, spike duration, spike and afterhyperpolarization (AHP) amplitude, spike threshold, cell capacitance, soma and somadendritic areas. The action potentials of these cells are normally triggered by a combination of sodium and calcium currents which may result in autonomous pacemaker activity. We here analyse the mechanisms of high-threshold calcium spikes which have been demonstrated in these cells the presence of TTX (tetrodotoxin). The parameters for calcium dynamics required to give calcium spikes are quite different from those for regular spiking which suggests the involvement of restricted parts of the soma-dendritic surface as has been found, for example, in hippocampal neurons.
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Affiliation(s)
- Henry C Tuckwell
- Max Planck Institute for Mathematics in the Sciences, Inselstr. 22, 04103 Leipzig, Germany.
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