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Arnold MR, Williams PH, McArthur JA, Archuleta AR, O'Neill CE, Hassell JE, Smith DG, Bachtell RK, Lowry CA. Effects of chronic caffeine exposure during adolescence and subsequent acute caffeine challenge during adulthood on rat brain serotonergic systems. Neuropharmacology 2019; 148:257-271. [PMID: 30579884 PMCID: PMC6438184 DOI: 10.1016/j.neuropharm.2018.12.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 12/13/2018] [Accepted: 12/15/2018] [Indexed: 01/09/2023]
Abstract
Caffeine is the most commonly used drug in the world. However, animal studies suggest that chronic consumption of caffeine during adolescence can result in enhanced anxiety-like behavioral responses during adulthood. One mechanism through which chronic caffeine administration may influence subsequent anxiety-like responses is through actions on brainstem serotonergic systems. In order to explore potential effects of chronic caffeine consumption on brainstem serotonergic systems, we evaluated the effects of a 28-day exposure to chronic caffeine (0.3 g/L; postnatal day 28-56) or vehicle administration in the drinking water, followed by 24 h caffeine withdrawal, and subsequent challenge with caffeine (30 mg/kg; s.c.) or vehicle in adolescent male rats. In Experiment 1, acute caffeine challenge induced a widespread activation of serotonergic neurons throughout the dorsal raphe nucleus (DR); this effect was attenuated in rats that had been exposed to chronic caffeine consumption. In Experiment 2, acute caffeine administration profoundly decreased tph2 and slc22a3 mRNA expression throughout the DR, with no effects on htr1a or slc6a4 mRNA expression. Chronic caffeine exposure for four weeks during adolescence was sufficient to decrease tph2 mRNA expression in the DR measured 28 h after caffeine withdrawal. Chronic caffeine administration during adolescence did not impact the ability of acute caffeine to decrease tph2 or slc22a3 mRNA expression. Together, these data suggest that both chronic caffeine administration during adolescence and acute caffeine challenge during adulthood are important determinants of serotonergic function and serotonergic gene expression, effects that may contribute to chronic effects of caffeine on anxiety-like responses.
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Affiliation(s)
- M R Arnold
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA.
| | - P H Williams
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, 80309, USA.
| | - J A McArthur
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, 80309, USA.
| | - A R Archuleta
- Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA; Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA.
| | - C E O'Neill
- Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA; Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA.
| | - J E Hassell
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, 80309, USA.
| | - D G Smith
- Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, CO, 80309, USA.
| | - R K Bachtell
- Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA; Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA.
| | - C A Lowry
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA; Department of Physical Medicine & Rehabilitation and Center for Neuroscience, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA; Veterans Health Administration, Rocky Mountain Mental Illness Research Education and Clinical Center, Denver Veterans Affairs Medical Center (VAMC), Denver, CO, 80220, USA; Military and Veteran Microbiome Consortium for Research and Education (MVM-CoRE), Denver, CO, 80220, USA.
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2
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Dedic N, Chen A, Deussing JM. The CRF Family of Neuropeptides and their Receptors - Mediators of the Central Stress Response. Curr Mol Pharmacol 2018; 11:4-31. [PMID: 28260504 PMCID: PMC5930453 DOI: 10.2174/1874467210666170302104053] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Revised: 11/26/2015] [Accepted: 08/03/2016] [Indexed: 12/12/2022]
Abstract
Background: Dysregulated stress neurocircuits, caused by genetic and/or environmental changes, underlie the development of many neuropsychiatric disorders. Corticotropin-releasing factor (CRF) is the major physiological activator of the hypothalamic-pituitary-adrenal (HPA) axis and conse-quently a primary regulator of the mammalian stress response. Together with its three family members, urocortins (UCNs) 1, 2, and 3, CRF integrates the neuroendocrine, autonomic, metabolic and behavioral responses to stress by activating its cognate receptors CRFR1 and CRFR2. Objective: Here we review the past and current state of the CRF/CRFR field, ranging from pharmacologi-cal studies to genetic mouse models and virus-mediated manipulations. Results: Although it is well established that CRF/CRFR1 signaling mediates aversive responses, includ-ing anxiety and depression-like behaviors, a number of recent studies have challenged this viewpoint by revealing anxiolytic and appetitive properties of specific CRF/CRFR1 circuits. In contrast, the UCN/CRFR2 system is less well understood and may possibly also exert divergent functions on physiol-ogy and behavior depending on the brain region, underlying circuit, and/or experienced stress conditions. Conclusion: A plethora of available genetic tools, including conventional and conditional mouse mutants targeting CRF system components, has greatly advanced our understanding about the endogenous mecha-nisms underlying HPA system regulation and CRF/UCN-related neuronal circuits involved in stress-related behaviors. Yet, the detailed pathways and molecular mechanisms by which the CRF/UCN-system translates negative or positive stimuli into the final, integrated biological response are not completely un-derstood. The utilization of future complementary methodologies, such as cell-type specific Cre-driver lines, viral and optogenetic tools will help to further dissect the function of genetically defined CRF/UCN neurocircuits in the context of adaptive and maladaptive stress responses.
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Affiliation(s)
- Nina Dedic
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Kraepelinstr, 2-10, 80804 Munich. Germany
| | - Alon Chen
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Kraepelinstr, 2-10, 80804 Munich. Germany
| | - Jan M Deussing
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Kraepelinstr, 2-10, 80804 Munich. Germany
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3
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Wagner S. Urocortins and their unfolding role in mammalian social behavior. Cell Tissue Res 2018; 375:133-142. [PMID: 30465153 DOI: 10.1007/s00441-018-2962-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 11/07/2018] [Indexed: 11/26/2022]
Abstract
The corticotropin-releasing factor (CRF) system is well known for its major role in coordinating the endocrine, autonomic and behavioral responses to stress. These functions have been shown to be mediated mainly by the binding of the CRF neuropeptide to its specific receptor CRFR1. Yet, the CRF system comprises several more neuropeptides, including the three urocortins, UCN1, UCN2 and UCN3, of which the latter two bind specifically to a distinct receptor-CRFR2. Unlike the brain-wide abundant expression of CRF and CRFR1, the brain expression of the urocortins and CRFR2 is rather restricted and seems to be focused in limbic areas associated with social behavior. Here, we will review accumulating evidence from recent studies that unfold the role of UCN2 and UCN3 in regulating mammalian social behavior, via activation of CRFR2.
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Affiliation(s)
- Shlomo Wagner
- Sagol Department of Neurobiology, the Integrated Brain and Behavior Research Center (IBBR), Faculty of Natural Sciences, University of Haifa, Mt. Carmel, 3498838, Haifa, Israel.
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Boukersi H, Lebaili N, Samson N, Granon S. Implication of regional brain serotonergic neurons in dorsal and median Raphé nuclei in adaptation to water lacking in Gerbillus tarabuli. J Chem Neuroanat 2018. [DOI: 10.1016/j.jchemneu.2018.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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5
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Russo AM, Lawther AJ, Prior BM, Isbel L, Somers WG, Lesku JA, Richdale AL, Dissanayake C, Kent S, Lowry CA, Hale MW. Social approach, anxiety, and altered tryptophan hydroxylase 2 activity in juvenile BALB/c and C57BL/6J mice. Behav Brain Res 2018; 359:918-926. [PMID: 29935278 DOI: 10.1016/j.bbr.2018.06.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 05/24/2018] [Accepted: 06/19/2018] [Indexed: 12/28/2022]
Abstract
Autism spectrum disorder (ASD) is a heterogeneous and highly heritable condition with multiple aetiologies. Although the biological mechanisms underlying ASD are not fully understood, evidence suggests that dysregulation of serotonergic systems play an important role in ASD psychopathology. Preclinical models using mice with altered serotonergic neurotransmission may provide insight into the role of serotonin in behaviours relevant to clinical features of ASD. For example, BALB/c mice carry a loss-of-function single nucleotide polymorphism (SNP; C1473 G) in tryptophan hydroxylase 2 (Tph2), which encodes the brain-specific isoform of the rate-limiting enzyme for serotonin synthesis, and these mice frequently have been used to model symptoms of ASD. In this study, juvenile male BALB/c (G/G; loss-of-function variant) and C57BL/6 J (C/C; wild type variant) mice, were exposed to the three-chamber sociability test, and one week later to the elevated plus-maze (EPM). Tryptophan hydroxylase 2 (TPH2) activity was measured following injection of the aromatic amino acid decarboxylase (AADC)-inhibitor, NSD-1015, and subsequent HPLC detection of 5-hydroxytryptophan (5-HTP) within subregions of the dorsal raphe nucleus (DR) and median raphe nucleus (MnR). The BALB/c mice showed reduced social behaviour and increased anxious behaviour, as well as decreased 5-HTP accumulation in the rostral and mid-rostrocaudal DR. In the full cohort of mice, TPH2 activity in the mid-rostrocaudal DR was correlated with anxious behaviour in the EPM, however these correlations were not statistically significant within each strain, suggesting that TPH2 activity was not directly associated with either anxiety or sociability. Further research is therefore required to more fully understand how serotonergic systems are involved in mouse behaviours that resemble some of the clinical features of ASD.
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Affiliation(s)
- Adrian M Russo
- School of Psychology and Public Health, La Trobe University, Melbourne, VIC, 3086, Australia
| | - Adam J Lawther
- School of Psychology and Public Health, La Trobe University, Melbourne, VIC, 3086, Australia
| | - Benjamin M Prior
- School of Psychology and Public Health, La Trobe University, Melbourne, VIC, 3086, Australia
| | - Luke Isbel
- School of Molecular Sciences, La Trobe University, Melbourne, VIC, 3086, Australia
| | - W Gregory Somers
- Olga Tennison Autism Research Centre, La Trobe University, Melbourne, VIC, 3086, Australia
| | - John A Lesku
- School of Life Sciences, La Trobe University, Melbourne, VIC, 3086, Australia
| | - Amanda L Richdale
- School of Psychology and Public Health, La Trobe University, Melbourne, VIC, 3086, Australia; Olga Tennison Autism Research Centre, La Trobe University, Melbourne, VIC, 3086, Australia
| | - Cheryl Dissanayake
- School of Psychology and Public Health, La Trobe University, Melbourne, VIC, 3086, Australia; Olga Tennison Autism Research Centre, La Trobe University, Melbourne, VIC, 3086, Australia
| | - Stephen Kent
- School of Psychology and Public Health, La Trobe University, Melbourne, VIC, 3086, Australia
| | - Christopher A Lowry
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Matthew W Hale
- School of Psychology and Public Health, La Trobe University, Melbourne, VIC, 3086, Australia.
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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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Kast RJ, Wu HH, Williams P, Gaspar P, Levitt P. Specific Connectivity and Unique Molecular Identity of MET Receptor Tyrosine Kinase Expressing Serotonergic Neurons in the Caudal Dorsal Raphe Nuclei. ACS Chem Neurosci 2017; 8:1053-1064. [PMID: 28375615 DOI: 10.1021/acschemneuro.7b00020] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Molecular characterization of neurons across brain regions has revealed new taxonomies for understanding functional diversity even among classically defined neuronal populations. Neuronal diversity has become evident within the brain serotonin (5-HT) system, which is far more complex than previously appreciated. However, until now it has been difficult to define subpopulations of 5-HT neurons based on molecular phenotypes. We demonstrate that the MET receptor tyrosine kinase (MET) is specifically expressed in a subset of 5-HT neurons within the caudal part of the dorsal raphe nuclei (DRC) that is encompassed by the classic B6 serotonin cell group. Mapping from embryonic day 16 through adulthood reveals that MET is expressed almost exclusively in the DRC as a condensed, paired nucleus, with an additional sparse set of MET+ neurons scattered within the median raphe. Retrograde tracing experiments reveal that MET-expressing 5-HT neurons provide substantial serotonergic input to the ventricular/subventricular region that contains forebrain stem cells, but do not innervate the dorsal hippocampus or entorhinal cortex. Conditional anterograde tracing experiments show that 5-HT neurons in the DRC/B6 target additional forebrain structures such as the medial and lateral septum and the ventral hippocampus. Molecular neuroanatomical analysis identifies 14 genes that are enriched in DRC neurons, including 4 neurotransmitter/neuropeptide receptors and 2 potassium channels. These analyses will lead to future studies determining the specific roles that 5-HTMET+ neurons contribute to the broader set of functions regulated by the serotonergic system.
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Affiliation(s)
| | | | | | - Patricia Gaspar
- Inserm, UMRS-839, Université
Pierre et Marie Curie, and Institut du Fer à Moulin, 75005, Paris, France
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8
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Wscieklica T, Silva MS, Lemes JA, Melo-Thomas L, Céspedes IC, Viana MB. Deep brain stimulation of the dorsal raphe inhibits avoidance and escape reactions and activates forebrain regions related to the modulation of anxiety/panic. Behav Brain Res 2017; 321:193-200. [DOI: 10.1016/j.bbr.2016.11.054] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 11/11/2016] [Accepted: 11/17/2016] [Indexed: 12/24/2022]
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9
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Donner NC, Siebler PH, Johnson DT, Villarreal MD, Mani S, Matti AJ, Lowry CA. Serotonergic systems in the balance: CRHR1 and CRHR2 differentially control stress-induced serotonin synthesis. Psychoneuroendocrinology 2016; 63:178-90. [PMID: 26454419 PMCID: PMC4695240 DOI: 10.1016/j.psyneuen.2015.09.024] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 09/21/2015] [Accepted: 09/22/2015] [Indexed: 12/14/2022]
Abstract
Anxiety and affective disorders are often associated with hypercortisolism and dysfunctional serotonergic systems, including increased expression of TPH2, the gene encoding the rate-limiting enzyme of neuronal serotonin synthesis. We previously reported that chronic glucocorticoid exposure is anxiogenic and increases rat Tph2 mRNA expression, but it was still unclear if this also translates to increased TPH2 protein levels and in vivo activity of the enzyme. Here, we found that adult male rats treated with corticosterone (CORT, 100 μg/ml) via the drinking water for 21 days indeed show increased TPH2 protein expression in the dorsal and ventral part of the dorsal raphe nucleus (DRD, DRV) during the light phase, abolishing the enzyme's diurnal rhythm. In a second study, we systemically blocked the conversion of 5-hydroxytryptophan (5-HTP) to serotonin immediately before rats treated with CORT or vehicle were either exposed to 30 min acoustic startle stress or home cage control conditions. This allowed us to measure 5-HTP accumulation as a direct readout of basal versus stress-induced in vivo TPH2 activity. As expected, basal TPH2 activity was elevated in the DRD, DRV and MnR of CORT-treated rats. In response to stress, a multitude of serotonergic systems reacted with increased TPH2 activity, but the stress-, anxiety-, and learned helplessness-related dorsal and caudal DR (DRD/DRC) displayed stress-induced increases in TPH2 activity only after chronic CORT-treatment. To address the mechanisms underlying this region-specific CORT-dependent sensitization, we stereotaxically implanted CORT-treated rats with cannulae targeting the DR, and pharmacologically blocked either corticotropin-releasing hormone receptor type 1 (CRHR1) or type 2 (CRHR2) 10 min prior to acoustic startle stress. CRHR2 blockade prevented stress-induced increases of TPH2 activity within the DRD/DRC, while blockade of CRHR1 potentiated stress-induced TPH2 activity in the entire DR. Stress-induced TPH2 activity in the DRD/DRC furthermore predicted TPH2 activity in the amygdala and in the caudal pontine reticular nucleus (PnC), while serotonin synthesis in the PnC was strongly correlated with the maximum startle response. Our data demonstrate that chronically elevated glucocorticoids sensitize stress- and anxiety-related serotonergic systems, and for the first time reveal competing roles of CRHR1 and CRHR2 on stress-induced in vivo serotonin synthesis.
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Affiliation(s)
- Nina C. Donner
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, 1725 Pleasant Street, 114 Clare Small, UCB 354, 80309 Boulder, CO, USA,Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Kraepelinstr. 2-10, 80804 Munich, Germany,Corresponding author at: Nina C. Donner, Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Kraepelinstr. 2-10, 80804 Munich, Germany. Tel.: +49 (0)89 30622 554
| | - Philip H. Siebler
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, 1725 Pleasant Street, 114 Clare Small, UCB 354, 80309 Boulder, CO, USA
| | - Danté T. Johnson
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, 1725 Pleasant Street, 114 Clare Small, UCB 354, 80309 Boulder, CO, USA
| | - Marcos D. Villarreal
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, 1725 Pleasant Street, 114 Clare Small, UCB 354, 80309 Boulder, CO, USA
| | - Sofia Mani
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, 1725 Pleasant Street, 114 Clare Small, UCB 354, 80309 Boulder, CO, USA
| | - Allison J. Matti
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, 1725 Pleasant Street, 114 Clare Small, UCB 354, 80309 Boulder, CO, USA
| | - Christopher A. Lowry
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, 1725 Pleasant Street, 114 Clare Small, UCB 354, 80309 Boulder, CO, USA
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Lopes DA, Lemes JA, Melo-Thomas L, Schor H, de Andrade JS, Machado CM, Horta-Júnior JA, Céspedes IC, Viana MB. Unpredictable chronic mild stress exerts anxiogenic-like effects and activates neurons in the dorsal and caudal region and in the lateral wings of the dorsal raphe nucleus. Behav Brain Res 2016; 297:180-6. [DOI: 10.1016/j.bbr.2015.10.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 10/01/2015] [Accepted: 10/03/2015] [Indexed: 10/22/2022]
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Daniel SE, Rainnie DG. Stress Modulation of Opposing Circuits in the Bed Nucleus of the Stria Terminalis. Neuropsychopharmacology 2016; 41:103-25. [PMID: 26096838 PMCID: PMC4677121 DOI: 10.1038/npp.2015.178] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 05/22/2015] [Accepted: 06/17/2015] [Indexed: 12/11/2022]
Abstract
The anterior bed nucleus of the stria terminalis (BNST) has been recognized as a critical structure in regulating trait anxiety, contextual fear memory, and appetitive behavior, and is known to be sensitive to stress manipulations. As one of the most complex structures in the central nervous system, the intrinsic circuitry of the BNST is largely unknown; however, recent technological developments have allowed researchers to begin to untangle the internal connections of the nucleus. This research has revealed the possibility of two opposing circuits, one anxiolytic and one anxiogenic, within the BNST, the relative strength of which determines the behavioral outcome. The balance of these pathways is critical in maintaining a normal physiological and behavioral state; however, stress and drugs of abuse can differentially affect the opposing circuitry within the nucleus to shift the balance to a pathological state. In this review, we will examine how stress interacts with the neuromodulators, corticotropin-releasing factor, norepinephrine, dopamine, and serotonin to affect the circuitry of the BNST as well as how synaptic plasticity in the BNST is modulated by stress, resulting in long-lasting changes in the circuit and behavioral state.
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Affiliation(s)
- Sarah E Daniel
- Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA
| | - Donald G Rainnie
- Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA
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Anxiogenic drug administration and elevated plus-maze exposure in rats activate populations of relaxin-3 neurons in the nucleus incertus and serotonergic neurons in the dorsal raphe nucleus. Neuroscience 2015; 303:270-84. [DOI: 10.1016/j.neuroscience.2015.06.052] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 06/24/2015] [Accepted: 06/24/2015] [Indexed: 12/20/2022]
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13
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Liu C, Liu X, Song F, Li J, Zhang X, Yang J. The effects of neuropeptide urocortin 2 on the spontaneous discharge and glutamatergic neurotransmission of striatum neurons. Neuropeptides 2015; 50:17-21. [PMID: 25837973 DOI: 10.1016/j.npep.2015.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 01/13/2015] [Accepted: 03/02/2015] [Indexed: 10/23/2022]
Abstract
The primary cause of the neurodegenerative process that underlies Parkinson's disease (PD) is still unknown. Different mechanisms probably contribute to triggering neuronal death in the nigro-striatum pathway. The neuropeptide urocortin 2 (UCN2) plays an important role in the regulation of striatum (STR) neurons projection. We investigated the effects of UCN2 on spontaneous discharge and glutamatergic responses in STR for a better understanding of the pathogenesis of PD. The experiment used microiontophoresis method to observe the effects of UCN2 on STR neurons' firing rates in vivo. Corticotrophin releasing factor receptor 2 (CRF-R2) selective inhibitor, astressin-2B (AST-2B), was administered simultaneously with UCN2 to investigate the effects of UCN2 on CRF-R2. Moreover, we further explored the effects of UCN2 on glutamatergic responses in STR neurons. We found that UCN2 could significantly inhibit the firing rate of 84% of the tested STR neurons, and its inhibitory effect followed a concentration-dependent manner. During the microiontophoresis of GLU, the excitatory firing of glutamatergic neurons could be attenuated by the addition of UCN2, but enhanced by the application of AST-2B. The results suggest that UCN2 could regulate the effects of STR neurotransmitters (GLU) via CRF-R2 and may thereby contribute to the improvement of PD.
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Affiliation(s)
- Chunna Liu
- Department of Pharmacology, Liaoning Medical University, JinZhou 121001, China.
| | - Xinyu Liu
- The First Affiliated Hospital of Liaoning Medical University, JinZhou 121001, China
| | - Feiran Song
- The China Medical University, ShenYang 110001, China
| | - Jian Li
- The First Affiliated Hospital of Liaoning Medical University, JinZhou 121001, China
| | - Xia Zhang
- Department of Pharmacology, Liaoning Medical University, JinZhou 121001, China
| | - Jing Yang
- Department of Pharmacology, Liaoning Medical University, JinZhou 121001, China
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14
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Smith JA, Pati D, Wang L, de Kloet AD, Frazier CJ, Krause EG. Hydration and beyond: neuropeptides as mediators of hydromineral balance, anxiety and stress-responsiveness. Front Syst Neurosci 2015; 9:46. [PMID: 25873866 PMCID: PMC4379895 DOI: 10.3389/fnsys.2015.00046] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 03/06/2015] [Indexed: 11/13/2022] Open
Abstract
Challenges to body fluid homeostasis can have a profound impact on hypothalamic regulation of stress responsiveness. Deficiencies in blood volume or sodium concentration leads to the generation of neural and humoral signals relayed through the hindbrain and circumventricular organs that apprise the paraventricular nucleus of the hypothalamus (PVH) of hydromineral imbalance. Collectively, these neural and humoral signals converge onto PVH neurons, including those that express corticotrophin-releasing factor (CRF), oxytocin (OT), and vasopressin, to influence their activity and initiate compensatory responses that alleviate hydromineral imbalance. Interestingly, following exposure to perceived threats to homeostasis, select limbic brain regions mediate behavioral and physiological responses to psychogenic stressors, in part, by influencing activation of the same PVH neurons that are known to maintain body fluid homeostasis. Here, we review past and present research examining interactions between hypothalamic circuits regulating body fluid homeostasis and those mediating behavioral and physiological responses to psychogenic stress.
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Affiliation(s)
- Justin A. Smith
- Laboratory of Dr. Eric Krause, Department of Pharmacodynamics, College of Pharmacy, University of FloridaGainesville, FL, USA
| | - Dipanwita Pati
- Laboratory of Dr. Charles Frazier, Department of Pharmacodynamics, College of Pharmacy, University of FloridaGainesville, FL, USA
| | - Lei Wang
- Laboratory of Dr. Eric Krause, Department of Pharmacodynamics, College of Pharmacy, University of FloridaGainesville, FL, USA
| | - Annette D. de Kloet
- Laboratory of Dr. Colin Sumners, Department of Physiology and Functional Genomics, College of Medicine, University of FloridaGainesville, FL, USA
| | - Charles J. Frazier
- Laboratory of Dr. Charles Frazier, Department of Pharmacodynamics, College of Pharmacy, University of FloridaGainesville, FL, USA
| | - Eric G. Krause
- Laboratory of Dr. Eric Krause, Department of Pharmacodynamics, College of Pharmacy, University of FloridaGainesville, FL, USA
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15
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Tong CK, Chen J, Cebrián-Silla A, Mirzadeh Z, Obernier K, Guinto CD, Tecott LH, García-Verdugo JM, Kriegstein A, Alvarez-Buylla A. Axonal control of the adult neural stem cell niche. Cell Stem Cell 2014; 14:500-11. [PMID: 24561083 DOI: 10.1016/j.stem.2014.01.014] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 12/05/2013] [Accepted: 01/24/2014] [Indexed: 10/25/2022]
Abstract
The ventricular-subventricular zone (V-SVZ) is an extensive germinal niche containing neural stem cells (NSCs) in the walls of the lateral ventricles of the adult brain. How the adult brain's neural activity influences the behavior of adult NSCs remains largely unknown. We show that serotonergic (5HT) axons originating from a small group of neurons in the raphe form an extensive plexus on most of the ventricular walls. Electron microscopy revealed intimate contacts between 5HT axons and NSCs (B1) or ependymal cells (E1) and these cells were labeled by a transsynaptic viral tracer injected into the raphe. B1 cells express the 5HT receptors 2C and 5A. Electrophysiology showed that activation of these receptors in B1 cells induced small inward currents. Intraventricular infusion of 5HT2C agonist or antagonist increased or decreased V-SVZ proliferation, respectively. These results indicate that supraependymal 5HT axons directly interact with NSCs to regulate neurogenesis via 5HT2C.
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Affiliation(s)
- Cheuk Ka Tong
- Department of Neurological Surgery and The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA 94143, USA; Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Jiadong Chen
- Department of Neurological Surgery and The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Arantxa Cebrián-Silla
- Laboratory of Comparative Neurobiology, Instituto Cavanilles, Universidad de Valencia, CIBERNED, Valencia 46980, Spain
| | - Zaman Mirzadeh
- Department of Neurosurgery, Barrow Neurological Institute, Phoenix, AZ 85013, USA
| | - Kirsten Obernier
- Department of Neurological Surgery and The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Cristina D Guinto
- Department of Neurological Surgery and The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Laurence H Tecott
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Psychiatry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Jose Manuel García-Verdugo
- Laboratory of Comparative Neurobiology, Instituto Cavanilles, Universidad de Valencia, CIBERNED, Valencia 46980, Spain; Unidad Mixta de Esclerosis Múltiple y Neurorregeneración, IIS Hospital La Fe, Valencia 46013, Spain
| | - Arnold Kriegstein
- Department of Neurological Surgery and The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA 94143, USA; Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Arturo Alvarez-Buylla
- Department of Neurological Surgery and The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA 94143, USA; Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA.
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16
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Goel N, Innala L, Viau V. Sex differences in serotonin (5-HT) 1A receptor regulation of HPA axis and dorsal raphe responses to acute restraint. Psychoneuroendocrinology 2014; 40:232-41. [PMID: 24485495 DOI: 10.1016/j.psyneuen.2013.11.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 11/21/2013] [Accepted: 11/22/2013] [Indexed: 11/25/2022]
Abstract
The serotonin (5-HT) 1A receptor subtype has been implicated as an important mediator for the stimulatory influence of serotonin on stress hypothalamic-pituitary-adrenal (HPA) activity, at least in males. Females show greater HPA axis responses to stress compared to males. To determine the nature by which the 5-HT 1A receptor contributes to the sex difference in stress, we examined neuroendocrine and cellular (Fos) responses in male and female rats receiving systemic injections of the 5-HT 1A receptor antagonist, WAY 100635, prior to acute restraint exposure. WAY decreased the corticosterone response in males, but not in females. In the paraventricular nucleus of the hypothalamus (PVH), WAY produced similar decrements in the restraint-induced activation (Fos) of neuroendocrine neurons in males and females. In contrast to the PVH, WAY administration increased total Fos activation in the dorsal raphe nucleus, but only in males. WAY also provoked higher Fos responses within subsets of dorsal raphe cells identified as serotonergic (tryptophan hydroxylase-, TPH-ir) in both males and females. These data provide evidence to suggest a differential influence of presynaptic 5-HT 1A receptors to regulate the stress-induced recruitment of non-serotonergic dorsal raphe neurons in males and females. At present, we cannot rule out a possible role for estrogen in females to alter 5-HT outflow to the HPA axis. There was a negative correlation between estrogen and Fos responses within TPH-positive cells in the dorsal raphe of WAY-administered females, whereas a positive correlation was found between estrogen and 5-HT 1A mRNA expression localized to the region of the zona incerta in close proximity to the PVH. As the raphe complex and 5-HT system impinge on several central autonomic, behavioral and neuroendocrine control systems, the current findings provide an important framework for future studies directed at sex differences in adaptive homeostatic responses.
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Affiliation(s)
- Nirupa Goel
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - Leyla Innala
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - Victor Viau
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada V6T 1Z3.
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17
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Kormos V, Gaszner B. Role of neuropeptides in anxiety, stress, and depression: from animals to humans. Neuropeptides 2013; 47:401-19. [PMID: 24210138 DOI: 10.1016/j.npep.2013.10.014] [Citation(s) in RCA: 223] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 10/07/2013] [Accepted: 10/09/2013] [Indexed: 12/11/2022]
Abstract
Major depression, with its strikingly high prevalence, is the most common cause of disability in communities of Western type, according to data of the World Health Organization. Stress-related mood disorders, besides their deleterious effects on the patient itself, also challenge the healthcare systems with their great social and economic impact. Our knowledge on the neurobiology of these conditions is less than sufficient as exemplified by the high proportion of patients who do not respond to currently available medications targeting monoaminergic systems. The search for new therapeutical strategies became therefore a "hot topic" in neuroscience, and there is a large body of evidence suggesting that brain neuropeptides not only participate is stress physiology, but they may also have clinical relevance. Based on data obtained in animal studies, neuropeptides and their receptors might be targeted by new candidate neuropharmacons with the hope that they will become important and effective tools in the management of stress related mood disorders. In this review, we attempt to summarize the latest evidence obtained using animal models for mood disorders, genetically modified rodent models for anxiety and depression, and we will pay some attention to previously published clinical data on corticotropin releasing factor, urocortin 1, urocortin 2, urocortin 3, arginine-vasopressin, neuropeptide Y, pituitary adenylate-cyclase activating polypeptide, neuropeptide S, oxytocin, substance P and galanin fields of stress research.
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Affiliation(s)
- Viktória Kormos
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Pécs, Szigeti u. 12, H-7624 Pécs, Hungary; Molecular Pharmacology Research Group, János Szentágothai Research Center, University of Pécs, Ifjúság útja 20, H-7624 Pécs, Hungary; Department of Anatomy, Faculty of Medicine, University of Pécs, Szigeti u. 12, H-7624 Pécs, Hungary
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18
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Paul ED, Lowry CA. Functional topography of serotonergic systems supports the Deakin/Graeff hypothesis of anxiety and affective disorders. J Psychopharmacol 2013; 27:1090-106. [PMID: 23704363 DOI: 10.1177/0269881113490328] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Over 20 years ago, Deakin and Graeff hypothesized about the role of different serotonergic pathways in controlling the behavioral and physiologic responses to aversive stimuli, and how compromise of these pathways could lead to specific symptoms of anxiety and affective disorders. A growing body of evidence suggests these serotonergic pathways arise from topographically organized subpopulations of serotonergic neurons located in the dorsal and median raphe nuclei. We argue that serotonergic neurons in the dorsal/caudal parts of the dorsal raphe nucleus project to forebrain limbic regions involved in stress/conflict anxiety-related processes, which may be relevant for anxiety and affective disorders. Serotonergic neurons in the "lateral wings" of the dorsal raphe nucleus provide inhibitory control over structures controlling fight-or-flight responses. Dysfunction of this pathway could be relevant for panic disorder. Finally, serotonergic neurons in the median raphe nucleus, and the developmentally and functionally-related interfascicular part of the dorsal raphe nucleus, give rise to forebrain limbic projections that are involved in tolerance and coping with aversive stimuli, which could be important for affective disorders like depression. Elucidating the mechanisms through which stress activates these topographically and functionally distinct serotonergic pathways, and how dysfunction of these pathways leads to symptoms of neuropsychiatric disorders, may lead to the development of novel approaches to both the prevention and treatment of anxiety and affective disorders.
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Affiliation(s)
- Evan D Paul
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, Boulder, USA
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19
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Fox JH, Lowry CA. Corticotropin-releasing factor-related peptides, serotonergic systems, and emotional behavior. Front Neurosci 2013; 7:169. [PMID: 24065880 PMCID: PMC3778254 DOI: 10.3389/fnins.2013.00169] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 08/30/2013] [Indexed: 12/01/2022] Open
Abstract
Corticotropin-releasing factor (CRF) is a 41-amino acid neuropeptide that is involved in stress-related physiology and behavior, including control of the hypothalamic-pituitary-adrenal (HPA) axis. Members of the CRF family of neuropeptides, including urocortin 1 (UCN 1), UCN 2, and UCN 3, bind to the G protein-coupled receptors, CRF type 1 (CRF1) and CRF2 receptors. In addition, CRF binding protein (CRFBP) binds both CRF and UCN 1 and can modulate their activities. There are multiple mechanisms through which CRF-related peptides may influence emotional behavior, one of which is through altering the activity of brainstem neuromodulatory systems, including serotonergic systems. CRF and CRF-related peptides act within the dorsal raphe nucleus (DR), the major source for serotonin (5-HT) in the brain, to alter the neuronal activity of specific subsets of serotonergic neurons and to influence stress-related behavior. CRF-containing axonal fibers innervate the DR in a topographically organized manner, which may contribute to the ability of CRF to alter the activity of specific subsets of serotonergic neurons. CRF and CRF-related peptides can either increase or decrease serotonergic neuronal firing rates and serotonin release, depending on their concentrations and on the specific CRF receptor subtype(s) involved. This review aims to describe the interactions between CRF-related peptides and serotonergic systems, the consequences for stress-related behavior, and implications for vulnerability to anxiety and affective disorders.
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Affiliation(s)
- James H Fox
- Behavioral Neuroendocrinology Laboratory, Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder Boulder, CO, USA
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20
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Donner NC, Lowry CA. Sex differences in anxiety and emotional behavior. Pflugers Arch 2013; 465:601-26. [PMID: 23588380 DOI: 10.1007/s00424-013-1271-7] [Citation(s) in RCA: 227] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 03/13/2013] [Accepted: 03/13/2013] [Indexed: 12/14/2022]
Abstract
Research has elucidated causal links between stress exposure and the development of anxiety disorders, but due to the limited use of female or sex-comparative animal models, little is known about the mechanisms underlying sex differences in those disorders. This is despite an overwhelming wealth of evidence from the clinical literature that the prevalence of anxiety disorders is about twice as high in women compared to men, in addition to gender differences in severity and treatment efficacy. We here review human gender differences in generalized anxiety disorder, panic disorder, posttraumatic stress disorder and anxiety-relevant biological functions, discuss the limitations of classic conflict anxiety tests to measure naturally occurring sex differences in anxiety-like behaviors, describe sex-dependent manifestation of anxiety states after gestational, neonatal, or adolescent stressors, and present animal models of chronic anxiety states induced by acute or chronic stressors during adulthood. Potential mechanisms underlying sex differences in stress-related anxiety states include emerging evidence supporting the existence of two anatomically and functionally distinct serotonergic circuits that are related to the modulation of conflict anxiety and panic-like anxiety, respectively. We discuss how these serotonergic circuits may be controlled by reproductive steroid hormone-dependent modulation of crfr1 and crfr2 expression in the midbrain dorsal raphe nucleus and by estrous stage-dependent alterations of γ-aminobutyric acid (GABAergic) neurotransmission in the periaqueductal gray, ultimately leading to sex differences in emotional behavior.
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Affiliation(s)
- Nina C Donner
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, 1725 Pleasant Street, 114 Clare Small, Boulder, CO 80309-0354, USA.
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21
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Hale MW, Raison CL, Lowry CA. Integrative physiology of depression and antidepressant drug action: implications for serotonergic mechanisms of action and novel therapeutic strategies for treatment of depression. Pharmacol Ther 2012; 137:108-18. [PMID: 23017938 DOI: 10.1016/j.pharmthera.2012.09.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Accepted: 09/10/2012] [Indexed: 11/15/2022]
Abstract
Major depressive disorder (MDD) is predicted to be the second leading cause of disability worldwide by the year 2020. Currently available treatments for MDD are suboptimal. Only 50% of MDD patients recover in less than 12 weeks with adequate treatment, and up to 20% of patients will fail to adequately respond to all currently available interventions. Moreover, current treatments come at the cost of significant central nervous system (CNS) side effects, further highlighting the need for more effective treatments with fewer side effects. A greater mechanistic understanding of MDD and the actions of antidepressant drugs would provide opportunities for development of novel therapeutic approaches to treatment. With this aim in mind, we explore the novel, but empirically supported, hypothesis that an evolutionarily ancient thermoafferent pathway, signaling via the spinoparabrachial pathway from serotonergic sensory cells in the skin and other epithelial linings to serotonergic neurons and depression-related circuits in the brain, is dysfunctional in MDD and that antidepressant therapies, including antidepressant drugs and exercise, act by restoring its function.
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Affiliation(s)
- Matthew W Hale
- School of Psychological Science, La Trobe University, Melbourne 3086, Australia
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22
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Jasinska AJ, Lowry CA, Burmeister M. Serotonin transporter gene, stress and raphe-raphe interactions: a molecular mechanism of depression. Trends Neurosci 2012; 35:395-402. [PMID: 22301434 DOI: 10.1016/j.tins.2012.01.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2011] [Revised: 12/02/2011] [Accepted: 01/01/2012] [Indexed: 12/16/2022]
Abstract
Reports of gene-environment interactions (GxE) between the serotonin transporter gene and stress on risk of depression have generated both excitement and controversy. The controversy persists in part because a mechanistic account of this GxE on serotonergic neurotransmission and risk of depression has been lacking. In this Opinion, we draw on recent discoveries in the functional neuroanatomy of the serotonergic dorsal raphe nucleus (DR) to propose such a mechanistic account. We argue that genetically produced variability in serotonin reuptake during stressor-induced raphe-raphe interactions alters the balance in the amygdala-ventromedial prefrontal cortex (VMPFC)-DR circuitry underlying stressor reactivity and emotion regulation. In particular, the recently characterized stressor-responsive serotonergic interneurons originating from the dorsolateral DR may hold a key to unlocking the GxE mechanism of depression.
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Affiliation(s)
- Agnes J Jasinska
- Department of Psychology, University of Michigan, Ann Arbor, Michigan, USA.
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23
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Hale MW, Shekhar A, Lowry CA. Stress-related serotonergic systems: implications for symptomatology of anxiety and affective disorders. Cell Mol Neurobiol 2012; 32:695-708. [PMID: 22484834 DOI: 10.1007/s10571-012-9827-1] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 03/07/2012] [Indexed: 11/30/2022]
Abstract
Previous studies have suggested that serotonergic neurons in the midbrain raphe complex have a functional topographic organization. Recent studies suggest that stimulation of a bed nucleus of the stria terminalis-dorsal raphe nucleus pathway by stress- and anxiety-related stimuli modulates a subpopulation of serotonergic neurons in the dorsal part of the dorsal raphe nucleus (DRD) and caudal part of the dorsal raphe nucleus (DRC) that participates in facilitation of anxiety-like responses. In contrast, recent studies suggest that activation of a spinoparabrachial pathway by peripheral thermal or immune stimuli excites subpopulations of serotonergic neurons in the ventrolateral part of the dorsal raphe nucleus/ventrolateral periaqueducal gray (DRVL/VLPAG) region and interfascicular part of the dorsal raphe nucleus (DRI). Studies support a role for serotonergic neurons in the DRVL/VLPAG in inhibition of panic-like responses, and serotonergic neurons in the DRI in antidepressant-like effects. Thus, data suggest that while some subpopulations of serotonergic neurons in the dorsal raphe nucleus play a role in facilitation of anxiety-like responses, others play a role in inhibition of anxiety- or panic-like responses, while others play a role in antidepressant-like effects. Understanding the anatomical and functional properties of these distinct serotonergic systems may lead to novel therapeutic strategies for the prevention and/or treatment of affective and anxiety disorders. In this review, we describe the anatomical and functional properties of subpopulations of serotonergic neurons in the dorsal raphe nucleus, with a focus on those implicated in symptoms of anxiety and affective disorders, the DRD/DRC, DRVL/VLPAG, and DRI.
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Affiliation(s)
- Matthew W Hale
- School of Psychological Science, La Trobe University, Melbourne, Australia
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24
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Waselus M, Valentino RJ, Van Bockstaele EJ. Collateralized dorsal raphe nucleus projections: a mechanism for the integration of diverse functions during stress. J Chem Neuroanat 2011; 41:266-80. [PMID: 21658442 PMCID: PMC3156417 DOI: 10.1016/j.jchemneu.2011.05.011] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 05/18/2011] [Accepted: 05/20/2011] [Indexed: 01/01/2023]
Abstract
The midbrain dorsal raphe nucleus (DR) is the origin of the central serotonin (5-HT) system, a key neurotransmitter system that has been implicated in the expression of normal behaviors and in diverse psychiatric disorders, particularly affective disorders such as depression and anxiety. One link between the DR-5-HT system and affective disorders is exposure to stressors. Stress is a major risk factor for affective disorders, and stressors alter activity of DR neurons in an anatomically specific manner. Stress-induced changes in DR neuronal activity are transmitted to targets of the DR via ascending serotonergic projections, many of which collateralize to innervate multiple brain regions. Indeed, the collateralization of DR efferents allows for the coordination of diverse components of the stress response. This review will summarize our current understanding of the organization of the ascending DR system and its collateral projections. Using the neuropeptide corticotropin-releasing factor (CRF) system as an example of a stress-related initiator of DR activity, we will discuss how topographic specificity of afferent regulation of ascending DR circuits serves to coordinate activity in functionally diverse target regions under appropriate conditions.
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Affiliation(s)
- Maria Waselus
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109, United States.
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25
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Hale MW, Shekhar A, Lowry CA. Development by environment interactions controlling tryptophan hydroxylase expression. J Chem Neuroanat 2011; 41:219-26. [PMID: 21640184 DOI: 10.1016/j.jchemneu.2011.05.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 04/19/2011] [Accepted: 05/06/2011] [Indexed: 11/17/2022]
Abstract
Tryptophan hydroxylase is the rate-limiting enzyme in the biosynthesis of serotonin (5-hydroxytryptamine; 5-HT). Two isoforms of tryptophan hydroxylase, derived from different genes, tph1 and tph2, have been identified. The tph1 isoform is expressed in peripheral tissues, whereas tph2 is brain and neuron-specific. Recent studies suggest that tph2 expression and brain serotonin turnover are upregulated in depressed suicide patients, and drug-free depressed patients, respectively. Increased tph2 expression could result from genetic influences, early life developmental influences, adverse experience during adulthood, or interactions among these factors. Studies in rodents support the hypothesis that interactions between early life developmental influences and adverse experience during adulthood play an important role in determining tph2 expression. In this review, we highlight the evidence for the effects of adverse early life experience and stressful experience during adulthood on both tph1 and tph2 expression.
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Affiliation(s)
- Matthew W Hale
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, USA
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26
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Evidence for in vivo thermosensitivity of serotonergic neurons in the rat dorsal raphe nucleus and raphe pallidus nucleus implicated in thermoregulatory cooling. Exp Neurol 2011; 227:264-78. [DOI: 10.1016/j.expneurol.2010.11.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 10/27/2010] [Accepted: 11/15/2010] [Indexed: 11/17/2022]
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27
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Hale MW, Lowry CA. Functional topography of midbrain and pontine serotonergic systems: implications for synaptic regulation of serotonergic circuits. Psychopharmacology (Berl) 2011; 213:243-64. [PMID: 21088958 DOI: 10.1007/s00213-010-2089-z] [Citation(s) in RCA: 174] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Accepted: 10/29/2010] [Indexed: 12/20/2022]
Abstract
RATIONALE Dysfunction of serotonergic systems is thought to play an important role in a number of neurological and psychiatric disorders. Recent studies suggest that there is anatomical and functional diversity among serotonergic systems innervating forebrain systems involved in the control of physiologic and behavioral responses, including the control of emotional states. OBJECTIVE Here, we highlight the methods that have been used to investigate the heterogeneity of serotonergic systems and review the evidence for the unique anatomical, hodological, and functional properties of topographically organized subpopulations of serotonergic neurons in the midbrain and pontine raphe complex. CONCLUSION The emerging understanding of the topographically organized synaptic regulation of brainstem serotonergic systems, the topography of the efferent projections of these systems, and their functional properties, should enable identification of novel therapeutic approaches to treatment of neurological and psychiatric conditions that are associated with dysregulation of serotonergic systems.
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Affiliation(s)
- Matthew W Hale
- Department of Integrative Physiology, University of Colorado, Boulder, CO 80309-0354, USA
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28
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A triple urocortin knockout mouse model reveals an essential role for urocortins in stress recovery. Proc Natl Acad Sci U S A 2010; 107:19020-5. [PMID: 20937857 DOI: 10.1073/pnas.1013761107] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Responding to stressful events requires numerous adaptive actions involving integrated changes in the central nervous and neuroendocrine systems. Numerous studies have implicated dysregulation of stress-response mechanisms in the etiology of stress-induced psychopathophysiologies. The urocortin neuropeptides are members of the corticotropin-releasing factor family and are associated with the central stress response. In the current study, a triple-knockout (tKO) mouse model lacking all three urocortin genes was generated. Intriguingly, these urocortin tKO mice exhibit increased anxiety-like behaviors 24 h following stress exposure but not under unstressed conditions or immediately following exposure to acute stress. The inability of these mutants to recover properly from the exposure to an acute stress was associated with robust alterations in the expression profile of amygdalar genes and with dysregulated serotonergic function in stress-related neurocircuits. These findings position the urocortins as essential factors in the stress-recovery process and suggest the tKO mouse line as a useful stress-sensitive mouse model.
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