1
|
Higa GSV, Viana FJC, Francis-Oliveira J, Cruvinel E, Franchin TS, Marcourakis T, Ulrich H, De Pasquale R. Serotonergic neuromodulation of synaptic plasticity. Neuropharmacology 2024; 257:110036. [PMID: 38876308 DOI: 10.1016/j.neuropharm.2024.110036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 05/15/2024] [Accepted: 06/11/2024] [Indexed: 06/16/2024]
Abstract
Synaptic plasticity constitutes a fundamental process in the reorganization of neural networks that underlie memory, cognition, emotional responses, and behavioral planning. At the core of this phenomenon lie Hebbian mechanisms, wherein frequent synaptic stimulation induces long-term potentiation (LTP), while less activation leads to long-term depression (LTD). The synaptic reorganization of neuronal networks is regulated by serotonin (5-HT), a neuromodulator capable of modify synaptic plasticity to appropriately respond to mental and behavioral states, such as alertness, attention, concentration, motivation, and mood. Lately, understanding the serotonergic Neuromodulation of synaptic plasticity has become imperative for unraveling its impact on cognitive, emotional, and behavioral functions. Through a comparative analysis across three main forebrain structures-the hippocampus, amygdala, and prefrontal cortex, this review discusses the actions of 5-HT on synaptic plasticity, offering insights into its role as a neuromodulator involved in emotional and cognitive functions. By distinguishing between plastic and metaplastic effects, we provide a comprehensive overview about the mechanisms of 5-HT neuromodulation of synaptic plasticity and associated functions across different brain regions.
Collapse
Affiliation(s)
- Guilherme Shigueto Vilar Higa
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, São Paulo, SP, 05508-000, Brazil; Departamento de Bioquímica, Instituto de Química (USP), Butantã, São Paulo, SP, 05508-900, Brazil
| | - Felipe José Costa Viana
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, São Paulo, SP, 05508-000, Brazil
| | - José Francis-Oliveira
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35233, USA
| | - Emily Cruvinel
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, São Paulo, SP, 05508-000, Brazil
| | - Thainá Soares Franchin
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, São Paulo, SP, 05508-000, Brazil
| | - Tania Marcourakis
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Butantã, São Paulo, SP, 05508-000, Brazil
| | - Henning Ulrich
- Departamento de Bioquímica, Instituto de Química (USP), Butantã, São Paulo, SP, 05508-900, Brazil
| | - Roberto De Pasquale
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, São Paulo, SP, 05508-000, Brazil.
| |
Collapse
|
2
|
Payet JM, Stevens L, Russo AM, Jaehne EJ, van den Buuse M, Kent S, Lowry CA, Baratta MV, Hale MW. The Role of Dorsal Raphe Nucleus Serotonergic Systems in Emotional Learning and Memory in Male BALB/c Mice. Neuroscience 2023; 534:1-15. [PMID: 37852412 DOI: 10.1016/j.neuroscience.2023.10.003] [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: 08/14/2023] [Revised: 10/04/2023] [Accepted: 10/06/2023] [Indexed: 10/20/2023]
Abstract
Selective serotonin reuptake inhibitors (SSRIs) are the first-line pharmacological treatment for a variety of anxiety-, trauma- and stressor-related disorders. Although they are efficacious, therapeutic improvements require several weeks of treatment and are often associated with an initial exacerbation of symptoms. The dorsal raphe nucleus (DR) has been proposed as an important target for the modulation of emotional responses and the therapeutic effects of SSRIs. Using a fear-conditioning paradigm we aimed to understand how SSRIs affect emotional learning and memory, and their effects on serotonergic circuitry. Adult male BALB/c mice were treated with vehicle (n = 16) or the SSRI fluoxetine (18 mg/kg/d) acutely (n = 16), or chronically (21d, n = 16), prior to fear conditioning. Treatment was stopped, and half of the mice (n = 8/treatment group) were exposed to cued fear memory recall 72 h later. Activation of DR serotonergic neurons during fear conditioning (Experiment 1) or fear memory recall (Experiment 2), was measured using dual-label immunohistochemistry for Tph2 and c-Fos. Acute and chronic fluoxetine treatment reduced associative fear learning without affecting memory recall and had opposite effects on anxiety-like behaviour. Acute fluoxetine decreased serotonergic activity in the DR, while chronic treatment led to serotonergic activity that was indistinguishable from that of control levels in DRD and DRV subpopulations. Chronic fluoxetine facilitated fear extinction, which was associated with rostral DRD inhibition. These findings provide further evidence that SSRIs can alter aspects of learning and memory processes and are consistent with a role for discrete populations of DR serotonergic neurons in regulating fear- and anxiety-related behaviours.
Collapse
Affiliation(s)
- Jennyfer M Payet
- Department of Psychology, Counselling and Therapy, School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia
| | - Laura Stevens
- Department of Psychology, Counselling and Therapy, School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia
| | - Adrian M Russo
- Department of Psychology, Counselling and Therapy, School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia
| | - Emily J Jaehne
- Department of Psychology, Counselling and Therapy, School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia; Department of Psychiatry, School of Clinical Sciences, Monash University, Clayton, Victoria, Australia
| | - Maarten van den Buuse
- Department of Psychology, Counselling and Therapy, School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia
| | - Stephen Kent
- Department of Psychology, Counselling and Therapy, School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia
| | - Christopher A Lowry
- Department of Integrative Physiology and Centre for Neuroscience, University of Colorado Boulder, Boulder, Colorado, USA
| | - Michael V Baratta
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado, USA
| | - Matthew W Hale
- Department of Psychology, Counselling and Therapy, School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia.
| |
Collapse
|
3
|
Svalina MN, Sullivan R, Restrepo D, Huntsman MM. From circuits to behavior: Amygdala dysfunction in fragile X syndrome. Front Integr Neurosci 2023; 17:1128529. [PMID: 36969493 PMCID: PMC10034113 DOI: 10.3389/fnint.2023.1128529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 02/23/2023] [Indexed: 03/12/2023] Open
Abstract
Fragile X syndrome (FXS) is a neurodevelopmental disorder caused by a repeat expansion mutation in the promotor region of the FMR1 gene resulting in transcriptional silencing and loss of function of fragile X messenger ribonucleoprotein 1 protein (FMRP). FMRP has a well-defined role in the early development of the brain. Thus, loss of the FMRP has well-known consequences for normal cellular and synaptic development leading to a variety of neuropsychiatric disorders including an increased prevalence of amygdala-based disorders. Despite our detailed understanding of the pathophysiology of FXS, the precise cellular and circuit-level underpinnings of amygdala-based disorders is incompletely understood. In this review, we discuss the development of the amygdala, the role of neuromodulation in the critical period plasticity, and recent advances in our understanding of how synaptic and circuit-level changes in the basolateral amygdala contribute to the behavioral manifestations seen in FXS.
Collapse
Affiliation(s)
- Matthew N. Svalina
- Medical Scientist Training Program, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Regina Sullivan
- Brain Institute, Nathan Kline Institute, Orangeburg, NY, United States
- Child and Adolescent Psychiatry, Child Study Center, New York University School of Medicine, New York, NY, United States
| | - Diego Restrepo
- Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Molly M. Huntsman
- Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- *Correspondence: Molly M. Huntsman,
| |
Collapse
|
4
|
Hon OJ, DiBerto JF, Mazzone CM, Sugam J, Bloodgood DW, Hardaway JA, Husain M, Kendra A, McCall NM, Lopez AJ, Kash TL, Lowery-Gionta EG. Serotonin modulates an inhibitory input to the central amygdala from the ventral periaqueductal gray. Neuropsychopharmacology 2022; 47:2194-2204. [PMID: 35999277 PMCID: PMC9630515 DOI: 10.1038/s41386-022-01392-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 06/21/2022] [Accepted: 07/11/2022] [Indexed: 11/08/2022]
Abstract
Fear is an adaptive state that drives defensive behavioral responses to specific and imminent threats. The central nucleus of the amygdala (CeA) is a critical site of adaptations that are required for the acquisition and expression of fear, in part due to alterations in the activity of inputs to the CeA. Here, we characterize a novel GABAergic input to the CeA from the ventral periaqueductal gray (vPAG) using fiber photometry and ex vivo whole-cell slice electrophysiology combined with optogenetics and pharmacology. GABA transmission from this ascending vPAG-CeA input was enhanced by serotonin via activation of serotonin type 2 C (5HT2C) receptors. Results suggest that these receptors are presynaptic. Interestingly, we found that GABA release from the vPAG-CeA input is enhanced following fear learning via activation of 5HT2C receptors and that this pathway is dynamically engaged in response to aversive stimuli. Additionally, we characterized serotonin release in the CeA during fear learning and recall for the first time using fiber photometry coupled to a serotonin biosensor. Together, these findings describe a mechanism by which serotonin modulates GABA release from ascending vPAG GABA inputs to the CeA and characterize a role for this pathway in fear.
Collapse
Affiliation(s)
- Olivia J Hon
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jeffrey F DiBerto
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Christopher M Mazzone
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jonathan Sugam
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Daniel W Bloodgood
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - J Andrew Hardaway
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Mariya Husain
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Alexis Kendra
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Nora M McCall
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Alberto J Lopez
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Thomas L Kash
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Emily G Lowery-Gionta
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| |
Collapse
|
5
|
Constitutive 5-HT2C receptor knock-out facilitates fear extinction through altered activity of a dorsal raphe-bed nucleus of the stria terminalis pathway. Transl Psychiatry 2022; 12:487. [PMID: 36402746 PMCID: PMC9675804 DOI: 10.1038/s41398-022-02252-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 10/24/2022] [Accepted: 11/07/2022] [Indexed: 11/21/2022] Open
Abstract
Serotonin 2C receptors (5-HT2CRs) are widely distributed throughout the brain and are strongly implicated in the pathophysiology of anxiety disorders such as post-traumatic stress disorder (PTSD). Although in recent years, a considerable amount of evidence supports 5-HT2CRs facilitating effect on anxiety behavior, the involvement in learned fear responses and fear extinction is rather unexplored. Here, we used a 5-HT2CR knock-out mouse line (2CKO) to gain new insights into the involvement of 5-HT2CRs in the neuronal fear circuitry. Using a cued fear conditioning paradigm, our results revealed that global loss of 5-HT2CRs exclusively accelerates fear extinction, without affecting fear acquisition and fear expression. To investigate the neuronal substrates underlying the extinction enhancing effect, we mapped the immediate-early gene product cFos, a marker for neuronal activity, in the dorsal raphe nucleus (DRN), amygdala and bed nucleus of the stria terminalis (BNST). Surprisingly, besides extinction-associated changes, our results revealed alterations in neuronal activity even under basal home cage conditions in specific subregions of the DRN and the BNST in 2CKO mice. Neuronal activity in the dorsal BNST was shifted in an extinction-supporting direction due to 5-HT2CR knock-out. Finally, the assessment of DRN-BNST connectivity using antero- and retrograde tracing techniques uncovered a discrete serotonergic pathway projecting from the most caudal subregion of the DRN (DRC) to the anterodorsal portion of the BNST (BNSTad). This serotonergic DRC-BNSTad pathway showed increased neuronal activity in 2CKO mice. Thus, our results provide new insights for the fear extinction network by revealing a specific serotonergic DRC-BNSTad pathway underlying a 5-HT2CR-sensitive mechanism with high significance in the treatment of PTSD.
Collapse
|
6
|
Vázquez-León P, Miranda-Páez A, Valencia-Flores K, Sánchez-Castillo H. Defensive and Emotional Behavior Modulation by Serotonin in the Periaqueductal Gray. Cell Mol Neurobiol 2022; 43:1453-1468. [PMID: 35902460 DOI: 10.1007/s10571-022-01262-z] [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: 04/18/2022] [Accepted: 07/13/2022] [Indexed: 11/26/2022]
Abstract
Serotonin 5-hydroxytryptamine (5-HT) is a key neurotransmitter for the modulation and/or regulation of numerous physiological processes and psychiatric disorders (e.g., behaviors related to anxiety, pain, aggressiveness, etc.). The periaqueductal gray matter (PAG) is considered an integrating center for active and passive defensive behaviors, and electrical stimulation of this area has been shown to evoke behavioral responses of panic, fight-flight, freezing, among others. The serotonergic activity in PAG is influenced by the activation of other brain areas such as the medial hypothalamus, paraventricular nucleus of the hypothalamus, amygdala, dorsal raphe nucleus, and ventrolateral orbital cortex. In addition, activation of other receptors within PAG (i.e., CB1, Oxytocin, µ-opioid receptor (MOR), and γ-aminobutyric acid (GABAA)) promotes serotonin release. Therefore, this review aims to document evidence suggesting that the PAG-evoked behavioral responses of anxiety, panic, fear, analgesia, and aggression are influenced by the activation of 5-HT1A and 5-HT2A/C receptors and their participation in the treatment of various mental disorders.
Collapse
Affiliation(s)
- Priscila Vázquez-León
- Neuropsychopharmacology Laboratory, Psychology School. 1er Piso Edif. B. Cub B001, National Autonomous University of Mexico, Avenida Universidad 3000, Colonia Copilco Universidad. Alcaldía de Coyoacan, Mexico City, Mexico
| | - Abraham Miranda-Páez
- Department of Physiology, National School of Biological Sciences, National Polytechnic Institute, Wilfrido Massieu esq. Manuel Stampa S/N Col. Nueva Industrial Vallejo, Gustavo A. Madero, Mexico City, CP:07738, Mexico
| | - Kenji Valencia-Flores
- Neuropsychopharmacology Laboratory, Psychology School. 1er Piso Edif. B. Cub B001, National Autonomous University of Mexico, Avenida Universidad 3000, Colonia Copilco Universidad. Alcaldía de Coyoacan, Mexico City, Mexico
| | - Hugo Sánchez-Castillo
- Neuropsychopharmacology Laboratory, Psychology School. 1er Piso Edif. B. Cub B001, National Autonomous University of Mexico, Avenida Universidad 3000, Colonia Copilco Universidad. Alcaldía de Coyoacan, Mexico City, Mexico.
- Research Unit of Psychobiology and Neurosciences (UIPyN), Psychology School, UNAM, CDMX Mexico, CP 04510, Mexico.
| |
Collapse
|
7
|
Effects of Intra-BLA Administration of PPAR Antagonists on Formalin-Evoked Nociceptive Behaviour, Fear-Conditioned Analgesia, and Conditioned Fear in the Presence or Absence of Nociceptive Tone in Rats. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27062021. [PMID: 35335382 PMCID: PMC8949000 DOI: 10.3390/molecules27062021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/02/2022] [Accepted: 03/03/2022] [Indexed: 11/16/2022]
Abstract
There is evidence for the involvement of peroxisome proliferator-activated receptors (PPARs) in pain, cognition, and anxiety. However, their role in pain–fear interactions is unknown. The amygdala plays a key role in pain, conditioned fear, and fear-conditioned analgesia (FCA). We investigated the effects of intra-basolateral amygdala (BLA) administration of PPARα, PPARβ/δ, and PPARγ antagonists on nociceptive behaviour, FCA, and conditioned fear in the presence or absence of nociceptive tone. Male Sprague-Dawley (SD) rats received footshock (FC) or no footshock (NFC) in a conditioning arena. Twenty-three and a half hours later, rats received an intraplantar injection of formalin or saline and, 15 min later, intra-BLA microinjections of vehicle, PPARα (GW6471) PPARβ/δ (GSK0660), or PPARγ (GW9662) antagonists before arena re-exposure. Pain and fear-related behaviour were assessed, and neurotransmitters/endocannabinoids measured post-mortem. Intra-BLA administration of PPARα or PPARγ antagonists potentiated freezing in the presence of nociceptive tone. Blockade of all PPAR subtypes in the BLA increased freezing and BLA dopamine levels in NFC rats in the absence of nociceptive tone. Administration of intra-BLA PPARα and PPARγ antagonists increased levels of dopamine in the BLA compared with the vehicle-treated counterparts. In conclusion, PPARα and PPARγ in the BLA play a role in the expression or extinction of conditioned fear in the presence or absence of nociceptive tone.
Collapse
|
8
|
Hagsäter SM, Pettersson R, Pettersson C, Atanasovski D, Näslund J, Eriksson E. A Complex Impact of Systemically Administered 5-HT2A Receptor Ligands on Conditioned Fear. Int J Neuropsychopharmacol 2021; 24:749-757. [PMID: 34228806 PMCID: PMC8453278 DOI: 10.1093/ijnp/pyab040] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 05/26/2021] [Accepted: 07/05/2021] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Though drugs binding to serotonergic 5-HT2A receptors have long been claimed to influence human anxiety, it remains unclear if this receptor subtype is best described as anxiety promoting or anxiety dampening. Whereas conditioned fear expressed as freezing in rats is modified by application of 5-HT2A-acting drugs locally into different brain regions, reports on the effect of systemic administration of 5-HT2A receptor agonists and 5-HT2A antagonists or inverse agonists on this behavior remain sparse. METHODS We assessed the possible impact of systemic administration of 5-HT2A receptor agonists, 5-HT2A receptor inverse agonists, and a selective serotonin reuptake inhibitor (SSRI)-per se or in combination-on the freezing displayed by male rats when re-exposed to a conditioning chamber in which they received foot shocks 7 days earlier. RESULTS The 5-HT2A receptor agonists psilocybin and 25CN-NBOH induced a reduction in conditioned fear that was countered by pretreatment with 5-HT2A receptor inverse agonist MDL 100907. While both MDL 100907 and another 5-HT2A receptor inverse agonist, pimavanserin, failed to impact freezing per se, both compounds unmasked a robust fear-reducing effect of an SSRI, escitalopram, which by itself exerted no such effect. CONCLUSIONS The results indicate that 5-HT2A receptor activation is not a prerequisite for normal conditioned freezing in rats but that this receptor subtype, when selectively over-activated prior to expression, exerts a marked fear-reducing influence. However, in the presence of an SSRI, the 5-HT2A receptor, on the contrary, appears to counter an anti-freezing effect of the enhanced extracellular serotonin levels following reuptake inhibition.
Collapse
Affiliation(s)
- Sven Melker Hagsäter
- Department of Pharmacology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Robert Pettersson
- Department of Pharmacology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Christopher Pettersson
- Department of Pharmacology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Daniela Atanasovski
- Department of Pharmacology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Jakob Näslund
- Department of Pharmacology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Elias Eriksson
- Department of Pharmacology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden,Correspondence: Elias Eriksson, PhD, Department of Pharmacology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, POB 431, SE 405 30 Sweden ()
| |
Collapse
|
9
|
Abstract
OBJECTIVE Whereas numerous experimental and clinical studies suggest a complex involvement of serotonin in the regulation of anxiety, it remains to be clarified if the dominating impact of this transmitter is best described as anxiety-reducing or anxiety-promoting. The aim of this study was to assess the impact of serotonin depletion on acquisition, consolidation, and expression of conditioned fear. METHODS Male Sprague-Dawley rats were exposed to foot shocks as unconditioned stimulus and assessed with respect to freezing behaviour when re-subjected to context. Serotonin depletion was achieved by administration of a serotonin synthesis inhibitor, para-chlorophenylalanine (PCPA) (300 mg/kg daily × 3), (i) throughout the period from (and including) acquisition to (and including) expression, (ii) during acquisition but not expression, (iii) after acquisition only, and (iv) during expression only. RESULTS The time spent freezing was significantly reduced in animals that were serotonin-depleted during the entire period from (and including) acquisition to (and including) expression, as well as in those being serotonin-depleted during either acquisition only or expression only. In contrast, PCPA administrated immediately after acquisition, that is during memory consolidation, did not impact the expression of conditioned fear. CONCLUSION Intact serotonergic neurotransmission is important for both acquisition and expression of context-conditioned fear.
Collapse
|
10
|
Kolter JF, Hildenbrand MF, Popp S, Nauroth S, Bankmann J, Rother L, Waider J, Deckert J, Asan E, Jakob PM, Lesch KP, Schmitt-Böhrer A. Serotonin transporter genotype modulates resting state and predator stress-induced amygdala perfusion in mice in a sex-dependent manner. PLoS One 2021; 16:e0247311. [PMID: 33606835 PMCID: PMC7895400 DOI: 10.1371/journal.pone.0247311] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 02/04/2021] [Indexed: 12/16/2022] Open
Abstract
The serotonin transporter (5-HTT) is a key molecule of serotoninergic neurotransmission and target of many anxiolytics and antidepressants. In humans, 5-HTT gene variants resulting in lower expression levels are associated with behavioral traits of anxiety. Furthermore, functional magnetic resonance imaging (fMRI) studies reported increased cerebral blood flow (CBF) during resting state (RS) and amygdala hyperreactivity. 5-HTT deficient mice as an established animal model for anxiety disorders seem to be well suited for investigating amygdala (re-)activity in an fMRI study. We investigated wildtype (5-HTT+/+), heterozygous (5-HTT+/-), and homozygous 5-HTT-knockout mice (5-HTT-/-) of both sexes in an ultra-high-field 17.6 Tesla magnetic resonance scanner. CBF was measured with continuous arterial spin labeling during RS, stimulation state (SS; with odor of rats as aversive stimulus), and post-stimulation state (PS). Subsequently, post mortem c-Fos immunohistochemistry elucidated neural activation on cellular level. The results showed that in reaction to the aversive odor CBF in total brain and amygdala of all mice significantly increased. In male 5-HTT+/+ mice amygdala RS CBF levels were found to be significantly lower than in 5-HTT+/- mice. From RS to SS 5-HTT+/+ amygdala perfusion significantly increased compared to both 5-HTT+/- and 5-HTT-/- mice. Perfusion level changes of male mice correlated with the density of c-Fos-immunoreactive cells in the amygdaloid nuclei. In female mice the perfusion was not modulated by the 5-Htt-genotype, but by estrous cycle stages. We conclude that amygdala reactivity is modulated by the 5-Htt genotype in males. In females, gonadal hormones have an impact which might have obscured genotype effects. Furthermore, our results demonstrate experimental support for the tonic model of 5-HTTLPR function.
Collapse
Affiliation(s)
- Jann F. Kolter
- Department of Psychiatry, Psychosomatics and Psychotherapy, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany
- Division of Molecular Psychiatry, Department of Psychiatry, Psychosomatics and Psychotherapy, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany
| | - Markus F. Hildenbrand
- Department of Magnetic Resonance and X-Ray Imaging, Fraunhofer Development Center X-Ray Technology, Wuerzburg, Germany
| | - Sandy Popp
- Division of Molecular Psychiatry, Department of Psychiatry, Psychosomatics and Psychotherapy, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany
| | - Stephan Nauroth
- Division of Molecular Psychiatry, Department of Psychiatry, Psychosomatics and Psychotherapy, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany
| | - Julian Bankmann
- Department of Psychiatry, Psychosomatics and Psychotherapy, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany
| | - Lisa Rother
- Department of Psychiatry, Psychosomatics and Psychotherapy, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany
| | - Jonas Waider
- Division of Molecular Psychiatry, Department of Psychiatry, Psychosomatics and Psychotherapy, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany
| | - Jürgen Deckert
- Department of Psychiatry, Psychosomatics and Psychotherapy, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany
| | - Esther Asan
- Institute of Anatomy and Cell Biology, University of Wuerzburg, Wuerzburg, Germany
| | - Peter M. Jakob
- Department of Experimental Physics 5, University of Wuerzburg, Wuerzburg, Germany
| | - Klaus-Peter Lesch
- Division of Molecular Psychiatry, Department of Psychiatry, Psychosomatics and Psychotherapy, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany
| | - Angelika Schmitt-Böhrer
- Department of Psychiatry, Psychosomatics and Psychotherapy, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany
- * E-mail:
| |
Collapse
|
11
|
Bernabe CS, Caliman IF, Truitt WA, Molosh AI, Lowry CA, Hay-Schmidt A, Shekhar A, Johnson PL. Using loss- and gain-of-function approaches to target amygdala-projecting serotonergic neurons in the dorsal raphe nucleus that enhance anxiety-related and conditioned fear behaviors. J Psychopharmacol 2020; 34:400-411. [PMID: 32153226 PMCID: PMC9678127 DOI: 10.1177/0269881119900981] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The central serotonergic system originating from the dorsal raphe nucleus (DR) plays a critical role in anxiety and trauma-related disorders such as posttraumatic stress disorder. Although many studies have investigated the role of serotonin (5-HT) within pro-fear brain regions such as the amygdala, the majority of these studies have utilized non-selective pharmacological approaches or poorly understood lesioning techniques which limit their interpretation. AIM Here we investigated the role of amygdala-projecting 5-HT neurons in the DR in innate anxiety and conditioned fear behaviors. METHODS To achieve this goal, we utilized (1) selective lesion of 5-HT neurons projecting to the amygdala with saporin toxin conjugated to anti-serotonin transporter (SERT) injected into the amygdala, and (2) optogenetic excitation of amygdala-projecting DR cell bodies with a combination of a retrogradely transported canine adenovirus-expressing Cre-recombinase injected into the amygdala and a Cre-dependent-channelrhodopsin injected into the DR. RESULTS While saporin treatment lesioned both local amygdalar 5-HT fibers and neurons in the DR as well as reduced conditioned fear behavior, optical activation of amygdala-projecting DR neurons enhanced anxious behavior and conditioned fear response. CONCLUSION Collectively, these studies support the hypothesis that amygdala-projecting 5-HT neurons in the DR represent an anxiety and fear-on network.
Collapse
Affiliation(s)
- Cristian S. Bernabe
- Department of Anatomy & Cell Biology, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA,Stark Neurosciences Research Institute, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Izabela F. Caliman
- Department of Anatomy & Cell Biology, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - William A. Truitt
- Department of Anatomy & Cell Biology, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA,Stark Neurosciences Research Institute, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Andrei I. Molosh
- Stark Neurosciences Research Institute, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Christopher A. Lowry
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | | | - Anantha Shekhar
- Stark Neurosciences Research Institute, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Philip L. Johnson
- Department of Anatomy & Cell Biology, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA,Stark Neurosciences Research Institute, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| |
Collapse
|
12
|
Lima‐Maximino M, Pyterson MP, Carmo Silva RX, Gomes GCV, Rocha SP, Herculano AM, Rosemberg DB, Maximino C. Phasic and tonic serotonin modulate alarm reactions and post‐exposure behavior in zebrafish. J Neurochem 2020; 153:495-509. [DOI: 10.1111/jnc.14978] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 02/03/2020] [Accepted: 02/03/2020] [Indexed: 01/15/2023]
Affiliation(s)
- Monica Lima‐Maximino
- Laboratório de Neurofarmacologia e Biofísica Centro de Ciências Biológicas e da Saúde Departamento de Morfologia e Ciências Fisiológicas Universidade do Estado do Pará Marabá Brazil
| | - Maryana Pereira Pyterson
- Laboratório de Neurociências e Comportamento “Frederico Guilherme Graeff” Faculdade de Psicologia Universidade Federal do Sul e Sudeste do Pará Marabá Brazil
| | - Rhayra Xavier Carmo Silva
- Laboratório de Neurociências e Comportamento “Frederico Guilherme Graeff” Faculdade de Psicologia Universidade Federal do Sul e Sudeste do Pará Marabá Brazil
- Programa de Pós‐Graduação em Neurociências e Biologia Celular Instituto de Ciências Biológicas Universidade Federal do Pará Belém Brazil
| | - Gabriela Cristini Vidal Gomes
- Laboratório de Neurociências e Comportamento “Frederico Guilherme Graeff” Faculdade de Psicologia Universidade Federal do Sul e Sudeste do Pará Marabá Brazil
| | - Sueslene Prado Rocha
- Laboratório de Neurofarmacologia e Biofísica Centro de Ciências Biológicas e da Saúde Departamento de Morfologia e Ciências Fisiológicas Universidade do Estado do Pará Marabá Brazil
| | - Anderson Manoel Herculano
- Laboratório de Neurofarmacologia Experimental Instituto de Ciências Biológicas Universidade Federal do Pará Belém Brazil
| | - Denis Broock Rosemberg
- Laboratório de Neuropsicobiologia Experimental Departamento de Bioquímica e Biologia Molecular Centro de Ciências Naturais e Exatas Universidade Federal de Santa Maria Santa Maria Brazil
| | - Caio Maximino
- Laboratório de Neurociências e Comportamento “Frederico Guilherme Graeff” Faculdade de Psicologia Universidade Federal do Sul e Sudeste do Pará Marabá Brazil
| |
Collapse
|
13
|
Selective serotonin reuptake inhibition increases noise burst-induced unconditioned and context-conditioned freezing. Acta Neuropsychiatr 2019; 31:46-51. [PMID: 30404671 DOI: 10.1017/neu.2018.26] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
OBJECTIVE Whereas long-term administration of selective serotonin reuptake inhibitors (SSRIs) is effective for the treatment of anxiety disorders, acute administration of these drugs may exert a paradoxical anxiogenic effect. The aim of the present study was to explore the possible effect of an SSRI in situations of unconditioned or limited conditioned fear. METHODS Male Sprague Dawley rats were administered a single dose of an SSRI, escitalopram, before acquisition or expression of context conditioned fear, where noise bursts were used as the unconditioned stimulus. Freezing was assessed as a measure of unconditioned fear (=the acute response to noise bursts) or conditioned fear (=the response to the context), respectively. RESULTS Noise bursts elicited an acute increase in freezing but no robust conditioned response 7 days after exposure. Administration of escitalopram before testing exacerbated the freezing response during presentation of the unconditioned stimulus and also unmasked a conditioned response; in contrast, administration of escitalopram prior to acquisition did not influence the conditioned response. CONCLUSION The data suggest that freezing in rats exposed to a stimulus inducing relatively mild fear may be enhanced by acute pretreatment with an SSRI regardless of whether the freezing displayed by the animals is an acute unconditioned response to the stimulus in question or a conditioned response to the same stimulus.
Collapse
|
14
|
Lebois LAM, Seligowski AV, Wolff JD, Hill SB, Ressler KJ. Augmentation of Extinction and Inhibitory Learning in Anxiety and Trauma-Related Disorders. Annu Rev Clin Psychol 2019; 15:257-284. [PMID: 30698994 DOI: 10.1146/annurev-clinpsy-050718-095634] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Although the fear response is an adaptive response to threatening situations, a number of psychiatric disorders feature prominent fear-related symptoms caused, in part, by failures of extinction and inhibitory learning. The translational nature of fear conditioning paradigms has enabled us to develop a nuanced understanding of extinction and inhibitory learning based on the molecular substrates to systems neural circuitry and psychological mechanisms. This knowledge has facilitated the development of novel interventions that may augment extinction and inhibitory learning. These interventions include nonpharmacological techniques, such as behavioral methods to implement during psychotherapy, as well as device-based stimulation techniques that enhance or reduce activity in different regions of the brain. There is also emerging support for a number of psychopharmacological interventions that may augment extinction and inhibitory learning specifically if administered in conjunction with exposure-based psychotherapy. This growing body of research may offer promising novel techniques to address debilitating transdiagnostic fear-related symptoms.
Collapse
Affiliation(s)
- Lauren A M Lebois
- Division of Depression and Anxiety Disorders, Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts 02478, USA;
| | - Antonia V Seligowski
- Division of Depression and Anxiety Disorders, Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts 02478, USA;
| | - Jonathan D Wolff
- Division of Depression and Anxiety Disorders, Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts 02478, USA;
| | - Sarah B Hill
- Division of Depression and Anxiety Disorders, Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts 02478, USA;
| | - Kerry J Ressler
- Division of Depression and Anxiety Disorders, Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts 02478, USA;
| |
Collapse
|
15
|
Assessment of fear and anxiety associated behaviors, physiology and neural circuits in rats with reduced serotonin transporter (SERT) levels. Transl Psychiatry 2019; 9:33. [PMID: 30670681 PMCID: PMC6343029 DOI: 10.1038/s41398-019-0368-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 08/15/2018] [Accepted: 10/05/2018] [Indexed: 01/11/2023] Open
Abstract
Genetic variation in serotonin transporter (SERT) that reduces transcriptional efficiency is associated with higher anxiety and fear traits and a greater incidence of post traumatic stress disorder (PTSD). Although previous studies have shown that rats with no expression of SERT (SERT-/-) have increased baseline anxiety behaviors, SERT+/- rats with low SERT expression (and more relevant to the clinical condition with low SERT expression) do not. Yet, no systematic studies of fear acquisition/extinction or their underlying neural mechanisms have been conducted in this preclinical genetic SERT+/- model. Here we sought to determine if SERT+/- or SERT-/-, compared to wildtype, rats would show exacerbated panic responses and/or persistent conditioned fear responses that may be associated with PTSD or phobia vulnerability. Results: Only SERT-/- rats showed increased baseline anxiety-like behaviors with heightened panic respiratory responses. However SERT+/- (also SERT-/-) rats showed enhanced acquisition of fear and delayed extinction of fear that was associated with changes in serotonergic-related genes (e.g., reduced 5-HT1A receptor) and disrupted inhibition within the basolateral amygdala (BLA). Furthermore, the disrupted fear responses in SERT+/- rats were normalized with 5HT1A antagonist infusions into the BLA. Enhanced acquisition and failure to extinguish fear memories displayed by both SERT-/- and SERT+/- rats are cardinal symptoms of disabling anxiety disorders such as phobias and PTSD. The data here support the hypothesis that reduced SERT function is a genetic risk that disrupts select gene expression and network properties in the amygdala that could result in vulnerability to these syndromes.
Collapse
|
16
|
Schipper P, Henckens MJAG, Lopresto D, Kozicz T, Homberg JR. Acute inescapable stress alleviates fear extinction recall deficits caused by serotonin transporter abolishment. Behav Brain Res 2017; 346:16-20. [PMID: 29233642 DOI: 10.1016/j.bbr.2017.12.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 12/07/2017] [Accepted: 12/07/2017] [Indexed: 10/18/2022]
Abstract
Life stress increases risk for developing post-traumatic stress disorder (PTSD), and more prominently so in short-allele carriers of the serotonin transporter linked polymorphic region (5-HTTLPR). Serotonin transporter knockout (5-HTT-/-) rats show compromised extinction (recall) of conditioned fear, which might mediate the increased risk for PTSD and reduce the therapeutic efficacy of exposure therapy. Here, we assessed whether acute inescapable stress (IS) differentially affects fear extinction and extinction recall in 5-HTT-/- rats and wildtype controls. Surprisingly, IS experience improved fear extinction recall in 5-HTT-/- rats to the level of wildtype animals, while wildtypes were unaffected by this IS. Thus, whereas 5-HTT-/- rats evidently were more responsive to the stressor, the behavioral consequences presented themselves as adaptive.
Collapse
Affiliation(s)
- Pieter Schipper
- Department of Cognitive Neuroscience, Centre for Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Geert Grooteplein 21 (Route 126), 6525 EZ Nijmegen, The Netherlands
| | - Marloes J A G Henckens
- Department of Cognitive Neuroscience, Centre for Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Geert Grooteplein 21 (Route 126), 6525 EZ Nijmegen, The Netherlands
| | - Dora Lopresto
- Department of Cognitive Neuroscience, Centre for Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Geert Grooteplein 21 (Route 126), 6525 EZ Nijmegen, The Netherlands
| | - Tamas Kozicz
- Anatomy Department, Centre for Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Geert Grooteplein 21 (Route 109), 6525 EZ Nijmegen, The Netherlands
| | - Judith R Homberg
- Department of Cognitive Neuroscience, Centre for Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Geert Grooteplein 21 (Route 126), 6525 EZ Nijmegen, The Netherlands.
| |
Collapse
|
17
|
Fox JH, Hassell JE, Siebler PH, Arnold MR, Lamb AK, Smith DG, Day HEW, Smith TM, Simmerman EM, Outzen AA, Holmes KS, Brazell CJ, Lowry CA. Preimmunization with a heat-killed preparation of Mycobacterium vaccae enhances fear extinction in the fear-potentiated startle paradigm. Brain Behav Immun 2017; 66:70-84. [PMID: 28888667 DOI: 10.1016/j.bbi.2017.08.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 08/02/2017] [Accepted: 08/15/2017] [Indexed: 12/31/2022] Open
Abstract
The hygiene hypothesis or "Old Friends" hypothesis proposes that inflammatory diseases are increasing in modern urban societies, due in part to reduced exposure to microorganisms that drive immunoregulatory circuits, and a failure to terminate inappropriate inflammatory responses. Inappropriate inflammation is also emerging as a risk factor for trauma-related, anxiety, and affective disorders, including posttraumatic stress disorder (PTSD), which is characterized as persistent re-experiencing of the trauma after a traumatic experience. Traumatic experiences can lead to long-lasting fear memories and exaggerated fear potentiation of the acoustic startle reflex. The acoustic startle reflex is an ethologically relevant reflex and can be potentiated in both humans and rats through Pavlovian conditioning. Mycobacterium vaccae NCTC 11659 is a soil-derived bacterium with immunoregulatory and anti-inflammatory properties that has been demonstrated to confer stress resilience in mice. Here we immunized adult male Sprague Dawley rats 3×, once per week, with a heat-killed preparation of M. vaccae NCTC 11659 (0.1mg, s.c., in 100µl borate-buffered saline) or vehicle, and, then, 3weeks following the final immunization, tested them in the fear-potentiated startle paradigm; controls were maintained under home cage control conditions throughout the experiment (n=11-12 per group). Rats were tested on days 1 and 2 for baseline acoustic startle, received fear conditioning on days 3 and 4, and underwent fear extinction training on days 5-10. Rats were euthanized on day 11 and brain tissue was sectioned for analysis of mRNA expression for genes important in control of brain serotonergic signaling, including tph2, htr1a, slc6a4, and slc22a3, throughout the brainstem dorsal and median raphe nuclei. Immunization with M. vaccae had no effect on baseline acoustic startle or fear expression on day 5. However, M. vaccae-immunized rats showed enhanced between-session and within-session extinction on day 6, relative to vehicle-immunized controls. Immunization with M. vaccae and fear-potentiated startle altered serotonergic gene expression in a gene- and subregion-specific manner. These data are consistent with the hypothesis that immunoregulatory strategies, such as preimmunization with M. vaccae, have potential for prevention of stress- and trauma-related psychiatric disorders.
Collapse
Affiliation(s)
- James H Fox
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0354, USA.
| | - James E Hassell
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0354, USA.
| | - Philip H Siebler
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0354, USA.
| | - Mathew R Arnold
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0354, USA.
| | - Andrew K Lamb
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0354, USA.
| | - David G Smith
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0354, USA.
| | - Heidi E W Day
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA.
| | - Tessa M Smith
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0354, USA.
| | - Emma M Simmerman
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0354, USA.
| | - Alexander A Outzen
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0354, USA.
| | - Kaley S Holmes
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0354, USA.
| | - Christopher J Brazell
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0354, USA.
| | - Christopher A Lowry
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0354, USA; Department of Physical Medicine & Rehabilitation and Center for Neuroscience, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Rocky Mountain Mental Illness Research Education and Clinical Center, Denver, CO 80220, USA; Military and Veteran Microbiome Consortium for Research and Education (MVM-CoRE), Denver, CO 80220, USA.
| |
Collapse
|
18
|
Johnson PL, Molosh A, Fitz SD, Arendt D, Deehan GA, Federici LM, Bernabe C, Engleman EA, Rodd ZA, Lowry CA, Shekhar A. Pharmacological depletion of serotonin in the basolateral amygdala complex reduces anxiety and disrupts fear conditioning. Pharmacol Biochem Behav 2016; 138:174-9. [PMID: 26476009 DOI: 10.1016/j.pbb.2015.09.021] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 09/28/2015] [Accepted: 09/29/2015] [Indexed: 01/12/2023]
Abstract
The basolateral and lateral amygdala nuclei complex (BLC) is implicated in a number of emotional responses including conditioned fear and social anxiety. Based on previous studies demonstrating that enhanced serotonin release in the BLC leads to increased anxiety and fear responses, we hypothesized that pharmacologically depleting serotonin in the BLC using 5,7-dihydroxytryptamine (5,7-DHT) injections would lead to diminished anxiety and disrupted fear conditioning. To test this hypothesis, 5,7-DHT(a serotonin-depleting agent) was bilaterally injected into the BLC. Desipramine (a norepinephrine reuptake inhibitor) was systemically administered to prevent non-selective effects on norepinephrine. After 5days, 5-7-DHT-treated rats showed increases in the duration of social interaction (SI) time, suggestive of reduced anxiety-like behavior. We then used a cue-induced fear conditioning protocol with shock as the unconditioned stimulus and tone as the conditioned stimulus for rats pretreated with bilateral 5,7-DHT, or vehicle, injections into the BLC. Compared to vehicle-treated rats, 5,7-DHT rats had reduced acquisition of fear during conditioning (measured by freezing time during tone), also had reduced fear retrieval/recall on subsequent testing days. Ex vivo analyses revealed that 5,7-DHT reduced local 5-HT concentrations in the BLC by ~40% without altering local norepinephrine or dopamine concentrations. These data provide additional support for 5-HT playing a critical role in modulating anxiety-like behavior and fear-associated memories through its actions within the BLC.
Collapse
Affiliation(s)
- Philip L Johnson
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA; Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA; Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA,.
| | - Andrei Molosh
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA; Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Stephanie D Fitz
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Dave Arendt
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Gerald A Deehan
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Lauren M Federici
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA; Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Cristian Bernabe
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Eric A Engleman
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Zachary A Rodd
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA; Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Christopher A Lowry
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - Anantha Shekhar
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA; Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| |
Collapse
|
19
|
Gambeta E, de Souza CP, de Morais H, Zanoveli JM. Reestablishment of the hyperglycemia to the normal levels seems not to be essential to the anxiolytic-like effect induced by insulin. Metab Brain Dis 2016; 31:563-71. [PMID: 26608284 DOI: 10.1007/s11011-015-9770-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 11/17/2015] [Indexed: 01/29/2023]
Abstract
Diabetes is a chronic metabolic disease accompanied by several comorbidities, including neuropsychiatric conditions. Since the hyperglycemia appears to be the primary factor involved in diabetic conditions, we examined the effect of insulin treatment in diabetic rats on behavioral responses related to anxiety and aversive memory extinction. For this, normoglycemic (NGL) or streptozotocin-diabetic (DBT) rats were submitted to the elevated T maze (ETM) and the contextual conditioned fear (CCF) tests. Therefore, animals were subjected to the prolonged treatment with insulin (6 IU/day, s.c.) to investigate the effect of the treatment on distinct behaviors. When anxiety-like responses such as the inhibitory avoidance (IA) on the ETM and the time of freezing in the first session of the CCF test were evaluated, our data showed a more pronounced anxiogenic-like behavior in DBT animals when compared to NGL ones. In addition, an increased freezing time was observed in DBT animals exposed to the CCF test (sessions 2 and 3) when compared to the NGL group, suggestive of an impairment in the extinction of aversive memory. Insulin treatment induced an anxiolytic-like effect when IA and freezing time (session 1) was evaluated, but did not alter the impaired extinction of aversive memory (sessions 2 and 3). To better understand the involvement of a rigorous control of glycaemia, we also investigated the effect of a lower dose of insulin (3 IU/day, s.c.), unable to reestablish the hyperglycemia to the normal levels, on the same behavioral parameters. Our data show that independent of the dose of insulin, the same effects were observed when animals were evaluated in the ETM and CCF tests. However, only the highest dose of insulin was able to reduce the hyperglycemia to the normal levels. To conclude, our data suggest that a severe glycemic control by insulin treatment seems to be important, but not essential in improving diabetes-induced anxiety.
Collapse
Affiliation(s)
- Eder Gambeta
- Department of Pharmacology, Biological Sciences Building, Federal University of Paraná, Avenida Coronel H dos Santos S/N, P.O. Box 19031, Curitiba, PR, 81540-990, Brazil
| | - Camila Pasquini de Souza
- Department of Pharmacology, Biological Sciences Building, Federal University of Paraná, Avenida Coronel H dos Santos S/N, P.O. Box 19031, Curitiba, PR, 81540-990, Brazil
| | - Helen de Morais
- Department of Pharmacology, Biological Sciences Building, Federal University of Paraná, Avenida Coronel H dos Santos S/N, P.O. Box 19031, Curitiba, PR, 81540-990, Brazil
| | - Janaina Menezes Zanoveli
- Department of Pharmacology, Biological Sciences Building, Federal University of Paraná, Avenida Coronel H dos Santos S/N, P.O. Box 19031, Curitiba, PR, 81540-990, Brazil.
| |
Collapse
|
20
|
Baratta MV, Kodandaramaiah SB, Monahan PE, Yao J, Weber MD, Lin PA, Gisabella B, Petrossian N, Amat J, Kim K, Yang A, Forest CR, Boyden ES, Goosens KA. Stress Enables Reinforcement-Elicited Serotonergic Consolidation of Fear Memory. Biol Psychiatry 2016; 79:814-822. [PMID: 26248536 PMCID: PMC4698247 DOI: 10.1016/j.biopsych.2015.06.025] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 06/02/2015] [Accepted: 06/17/2015] [Indexed: 01/03/2023]
Abstract
BACKGROUND Prior exposure to stress is a risk factor for developing posttraumatic stress disorder (PTSD) in response to trauma, yet the mechanisms by which this occurs are unclear. Using a rodent model of stress-based susceptibility to PTSD, we investigated the role of serotonin in this phenomenon. METHODS Adult mice were exposed to repeated immobilization stress or handling, and the role of serotonin in subsequent fear learning was assessed using pharmacologic manipulation and western blot detection of serotonin receptors, measurements of serotonin, high-speed optogenetic silencing, and behavior. RESULTS Both dorsal raphe serotonergic activity during aversive reinforcement and amygdala serotonin 2C receptor (5-HT2CR) activity during memory consolidation were necessary for stress enhancement of fear memory, but neither process affected fear memory in unstressed mice. Additionally, prior stress increased amygdala sensitivity to serotonin by promoting surface expression of 5-HT2CR without affecting tissue levels of serotonin in the amygdala. We also showed that the serotonin that drives stress enhancement of associative cued fear memory can arise from paired or unpaired footshock, an effect not predicted by theoretical models of associative learning. CONCLUSIONS Stress bolsters the consequences of aversive reinforcement, not by simply enhancing the neurobiological signals used to encode fear in unstressed animals, but rather by engaging distinct mechanistic pathways. These results reveal that predictions from classical associative learning models do not always hold for stressed animals and suggest that 5-HT2CR blockade may represent a promising therapeutic target for psychiatric disorders characterized by excessive fear responses such as that observed in PTSD.
Collapse
MESH Headings
- Amygdala/drug effects
- Amygdala/metabolism
- Animals
- Association Learning/drug effects
- Association Learning/physiology
- Conditioning, Psychological/drug effects
- Conditioning, Psychological/physiology
- Disease Models, Animal
- Dorsal Raphe Nucleus/metabolism
- Electroshock
- Fear/drug effects
- Fear/physiology
- Male
- Memory Consolidation/drug effects
- Memory Consolidation/physiology
- Mice, Inbred C57BL
- Mice, Transgenic
- Models, Neurological
- Models, Psychological
- Neurons/drug effects
- Neurons/metabolism
- Optogenetics
- Receptor, Serotonin, 5-HT2C/metabolism
- Restraint, Physical
- Serotonin/metabolism
- Serotonin 5-HT2 Receptor Antagonists/pharmacology
- Serotonin Plasma Membrane Transport Proteins/genetics
- Serotonin Plasma Membrane Transport Proteins/metabolism
- Stress Disorders, Post-Traumatic/metabolism
- Stress, Psychological/physiopathology
Collapse
Affiliation(s)
- Michael V Baratta
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts; MIT Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Suhasa B Kodandaramaiah
- MIT Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts; The George W. Woodruff School of Mechanical Engineering (SBK, CRF), Georgia Institute of Technology, Atlanta, Georgia
| | - Patrick E Monahan
- MIT Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Junmei Yao
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Michael D Weber
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado
| | - Pei-Ann Lin
- MIT Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Barbara Gisabella
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Natalie Petrossian
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Jose Amat
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado
| | - Kyungman Kim
- MIT Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Aimei Yang
- MIT Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Craig R Forest
- The George W. Woodruff School of Mechanical Engineering (SBK, CRF), Georgia Institute of Technology, Atlanta, Georgia
| | - Edward S Boyden
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts; MIT Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Ki A Goosens
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts.
| |
Collapse
|
21
|
Bocchio M, McHugh SB, Bannerman DM, Sharp T, Capogna M. Serotonin, Amygdala and Fear: Assembling the Puzzle. Front Neural Circuits 2016; 10:24. [PMID: 27092057 PMCID: PMC4820447 DOI: 10.3389/fncir.2016.00024] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 03/21/2016] [Indexed: 11/13/2022] Open
Abstract
The fear circuitry orchestrates defense mechanisms in response to environmental threats. This circuitry is evolutionarily crucial for survival, but its dysregulation is thought to play a major role in the pathophysiology of psychiatric conditions in humans. The amygdala is a key player in the processing of fear. This brain area is prominently modulated by the neurotransmitter serotonin (5-hydroxytryptamine, 5-HT). The 5-HT input to the amygdala has drawn particular interest because genetic and pharmacological alterations of the 5-HT transporter (5-HTT) affect amygdala activation in response to emotional stimuli. Nonetheless, the impact of 5-HT on fear processing remains poorly understood.The aim of this review is to elucidate the physiological role of 5-HT in fear learning via its action on the neuronal circuits of the amygdala. Since 5-HT release increases in the basolateral amygdala (BLA) during both fear memory acquisition and expression, we examine whether and how 5-HT neurons encode aversive stimuli and aversive cues. Next, we describe pharmacological and genetic alterations of 5-HT neurotransmission that, in both rodents and humans, lead to altered fear learning. To explore the mechanisms through which 5-HT could modulate conditioned fear, we focus on the rodent BLA. We propose that a circuit-based approach taking into account the localization of specific 5-HT receptors on neurochemically-defined neurons in the BLA may be essential to decipher the role of 5-HT in emotional behavior. In keeping with a 5-HT control of fear learning, we review electrophysiological data suggesting that 5-HT regulates synaptic plasticity, spike synchrony and theta oscillations in the BLA via actions on different subcellular compartments of principal neurons and distinct GABAergic interneuron populations. Finally, we discuss how recently developed optogenetic tools combined with electrophysiological recordings and behavior could progress the knowledge of the mechanisms underlying 5-HT modulation of fear learning via action on amygdala circuits. Such advancement could pave the way for a deeper understanding of 5-HT in emotional behavior in both health and disease.
Collapse
Affiliation(s)
- Marco Bocchio
- MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford Oxford, UK
| | - Stephen B McHugh
- Department of Experimental Psychology, University of Oxford Oxford, UK
| | - David M Bannerman
- Department of Experimental Psychology, University of Oxford Oxford, UK
| | - Trevor Sharp
- Department of Pharmacology, University of Oxford Oxford, UK
| | - Marco Capogna
- MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford Oxford, UK
| |
Collapse
|
22
|
Wu ZM, Zheng CH, Zhu ZH, Wu FT, Ni GL, Liang Y. SiRNA-mediated serotonin transporter knockdown in the dorsal raphe nucleus rescues single prolonged stress-induced hippocampal autophagy in rats. J Neurol Sci 2015; 360:133-40. [PMID: 26723990 DOI: 10.1016/j.jns.2015.11.056] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 11/26/2015] [Accepted: 11/30/2015] [Indexed: 02/02/2023]
Abstract
The neurobiological mechanisms underlying the development of post-traumatic stress disorder (PTSD) remain elusive. One of the hypotheses is the dysfunction of serotonin (5-HT) neurotransmission, which is critically regulated by serotonin transporter (SERT). Therefore, we hypothesized that attenuation of SERT gene expression in the hippocampus could prevent hippocampal autophagy and the development of PTSD-like behavior. To this end, we infused SLC6A4 siRNAs into the dorsal raphe nucleus (DRN) to knockdown SERT gene expression after a single prolonged stress (SPS) treatment in rats. Then, we evaluated the effects of SERT gene knockdown on anxiety-related behaviors and extinction of contextual fear memory. We also examined the histological changes and the expression of Beclin-1, LC3-I, and LC3-II in the hippocampus. We found that SPS treatment did not alter anxiety-related behaviors but prolonged the extinction of contextual fear memory, and such a behavioral phenomenon was correlated with increased hippocampal autophagy, decreased 5-HT level, and increased expression of Beclin-1 and LC3-II/LC3-I ratio in the hippocampus. Furthermore, intra-DRN infusion of SLC6A4 siRNAs promoted the extinction of contextual fear memory, prevented hippocampal autophagy, increased 5-HT level, and decreased expression of Beclin-1 and LC3-II/LC3-I ratio. These results indicated that SERT may play a critical role in the pathogenesis of hippocampal autophagy, and is likely involved in the development of PTSD.
Collapse
Affiliation(s)
- Zhong-Min Wu
- Department of anatomy, Medical College of Taizhou University, Taizhou 318000, China; Department of Neurology, First People's Hospital of Linhai City, Linhai 317000, China
| | - Chun-Hua Zheng
- Outpatient Office, Taizhou Hospital, Taizhou 317000, China
| | - Zhen-Hua Zhu
- Department of Pediatrics, Taizhou Central Hospital, Taizhou 318000, China
| | - Feng-Tian Wu
- City Colloege of Zhejiang University, Hanzhou 310031, China
| | - Gui-Lian Ni
- Department of Neurology, First People's Hospital of Linhai City, Linhai 317000, China
| | - Yong Liang
- Department of anatomy, Medical College of Taizhou University, Taizhou 318000, China.
| |
Collapse
|
23
|
Bocchio M, Fucsina G, Oikonomidis L, McHugh SB, Bannerman DM, Sharp T, Capogna M. Increased Serotonin Transporter Expression Reduces Fear and Recruitment of Parvalbumin Interneurons of the Amygdala. Neuropsychopharmacology 2015; 40:3015-26. [PMID: 26052039 PMCID: PMC4864439 DOI: 10.1038/npp.2015.157] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 05/20/2015] [Accepted: 05/26/2015] [Indexed: 12/31/2022]
Abstract
Genetic association studies suggest that variations in the 5-hydroxytryptamine (5-HT; serotonin) transporter (5-HTT) gene are associated with susceptibility to psychiatric disorders such as anxiety or posttraumatic stress disorder. Individuals carrying high 5-HTT-expressing gene variants display low amygdala reactivity to fearful stimuli. Mice overexpressing the 5-HTT (5-HTTOE), an animal model of this human variation, show impaired fear, together with reduced fear-evoked theta oscillations in the basolateral amygdala (BLA). However, it is unclear how variation in 5-HTT gene expression impacts on the microcircuitry of the BLA to change behavior. We addressed this issue by investigating the activity of parvalbumin (PV)-expressing interneurons (PVINs), the biggest IN population in the basal amygdala (BA). We found that increased 5-HTT expression impairs the recruitment of PVINs (measured by their c-Fos immunoreactivity) during fear. Ex vivo patch-clamp recordings demonstrated that the depolarizing effect of 5-HT on PVINs was mediated by 5-HT2A receptor. In 5-HTTOE mice, 5-HT-evoked depolarization of PVINs and synaptic inhibition of principal cells, which provide the major output of the BA, were impaired. This deficit was because of reduced 5-HT2A function and not because of increased 5-HT uptake. Collectively, these findings provide novel cellular mechanisms that are likely to contribute to differences in emotional behaviors linked with genetic variations of the 5-HTT.
Collapse
Affiliation(s)
- Marco Bocchio
- MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Oxford, UK
| | - Giulia Fucsina
- MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Oxford, UK
| | - Lydia Oikonomidis
- MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Oxford, UK,Department of Pharmacology, University of Oxford, Oxford, UK,Department of Experimental Psychology, University of Oxford, Oxford, UK
| | - Stephen B McHugh
- Department of Experimental Psychology, University of Oxford, Oxford, UK
| | - David M Bannerman
- Department of Experimental Psychology, University of Oxford, Oxford, UK
| | - Trevor Sharp
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Marco Capogna
- MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Oxford, UK,MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3TH, UK, Tel: +44 1865 271897, Fax: +44 1865 271647, E-mail:
| |
Collapse
|
24
|
Singewald N, Schmuckermair C, Whittle N, Holmes A, Ressler KJ. Pharmacology of cognitive enhancers for exposure-based therapy of fear, anxiety and trauma-related disorders. Pharmacol Ther 2014; 149:150-90. [PMID: 25550231 PMCID: PMC4380664 DOI: 10.1016/j.pharmthera.2014.12.004] [Citation(s) in RCA: 273] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 12/24/2014] [Indexed: 12/20/2022]
Abstract
Pathological fear and anxiety are highly debilitating and, despite considerable advances in psychotherapy and pharmacotherapy they remain insufficiently treated in many patients with PTSD, phobias, panic and other anxiety disorders. Increasing preclinical and clinical evidence indicates that pharmacological treatments including cognitive enhancers, when given as adjuncts to psychotherapeutic approaches [cognitive behavioral therapy including extinction-based exposure therapy] enhance treatment efficacy, while using anxiolytics such as benzodiazepines as adjuncts can undermine long-term treatment success. The purpose of this review is to outline the literature showing how pharmacological interventions targeting neurotransmitter systems including serotonin, dopamine, noradrenaline, histamine, glutamate, GABA, cannabinoids, neuropeptides (oxytocin, neuropeptides Y and S, opioids) and other targets (neurotrophins BDNF and FGF2, glucocorticoids, L-type-calcium channels, epigenetic modifications) as well as their downstream signaling pathways, can augment fear extinction and strengthen extinction memory persistently in preclinical models. Particularly promising approaches are discussed in regard to their effects on specific aspects of fear extinction namely, acquisition, consolidation and retrieval, including long-term protection from return of fear (relapse) phenomena like spontaneous recovery, reinstatement and renewal of fear. We also highlight the promising translational value of the preclinial research and the clinical potential of targeting certain neurochemical systems with, for example d-cycloserine, yohimbine, cortisol, and L-DOPA. The current body of research reveals important new insights into the neurobiology and neurochemistry of fear extinction and holds significant promise for pharmacologically-augmented psychotherapy as an improved approach to treat trauma and anxiety-related disorders in a more efficient and persistent way promoting enhanced symptom remission and recovery.
Collapse
Affiliation(s)
- N Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, Leopold-Franzens University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria.
| | - C Schmuckermair
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, Leopold-Franzens University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - N Whittle
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, Leopold-Franzens University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - A Holmes
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
| | - K J Ressler
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA
| |
Collapse
|
25
|
Barkus C, Line SJ, Huber A, Capitao L, Lima J, Jennings K, Lowry J, Sharp T, Bannerman DM, McHugh SB. Variation in serotonin transporter expression modulates fear-evoked hemodynamic responses and theta-frequency neuronal oscillations in the amygdala. Biol Psychiatry 2014; 75:901-8. [PMID: 24120093 PMCID: PMC4032572 DOI: 10.1016/j.biopsych.2013.09.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 09/04/2013] [Accepted: 09/04/2013] [Indexed: 01/16/2023]
Abstract
BACKGROUND Gene association studies detect an influence of natural variation in the 5-hydroxytryptamine transporter (5-HTT) gene on multiple aspects of individuality in brain function, ranging from personality traits through to susceptibility to psychiatric disorders such as anxiety and depression. The neural substrates of these associations are unknown. Human neuroimaging studies suggest modulation of the amygdala by 5-HTT variation, but this hypothesis is controversial and unresolved, and difficult to investigate further in humans. METHODS We used a mouse model in which the 5-HTT is overexpressed throughout the brain and recorded hemodynamic responses (using a novel in vivo voltammetric monitoring method, analogous to blood oxygen level-dependent functional magnetic resonance imaging) and local field potentials during Pavlovian fear conditioning. RESULTS Increased 5-HTT expression impaired, but did not prevent, fear learning and significantly reduced amygdala hemodynamic responses to aversive cues. Increased 5-HTT expression was also associated with reduced theta oscillations, which were a feature of aversive cue presentation in controls. Moreover, in control mice, but not those with high 5-HTT expression, there was a strong correlation between theta power and the amplitude of the hemodynamic response. CONCLUSIONS Direct experimental manipulation of 5-HTT expression levels throughout the brain markedly altered fear learning, amygdala hemodynamic responses, and neuronal oscillations.
Collapse
Affiliation(s)
- Christopher Barkus
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Samantha J Line
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Anna Huber
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Liliana Capitao
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Joao Lima
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Katie Jennings
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - John Lowry
- Department of Chemistry, National University of Ireland, Maynooth, Ireland
| | - Trevor Sharp
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - David M Bannerman
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Stephen B McHugh
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom.
| |
Collapse
|
26
|
Bhorkar AA, Dandekar MP, Nakhate KT, Subhedar NK, Kokare DM. Involvement of the central melanocortin system in the effects of caffeine on anxiety-like behavior in mice. Life Sci 2013; 95:72-80. [PMID: 24361398 DOI: 10.1016/j.lfs.2013.12.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Revised: 12/07/2013] [Accepted: 12/10/2013] [Indexed: 12/12/2022]
Abstract
AIMS To investigate the role of the melanocortin (MC) system in the framework of the central nucleus of the amygdala (CeA) in the differential effects of the adenosine receptor blocker caffeine on anxiety-like behavior, using the social interaction (SI) test. MAIN METHODS Caffeine was injected intraperitoneally, alone or in combination with alpha-melanocyte stimulating hormone (α-MSH), the MC4 receptor agonist RO27-3225 or the antagonist HS014 via the intra-CeA route. The effects of chronic (21 days) caffeine, given alone or concurrently with α-MSH, or RO27-3225, were investigated. The effects of withdrawal of these treatments on SI time were also evaluated. Furthermore, the acute effects of HS014 were investigated in different sets of caffeine-withdrawn mice. KEY FINDINGS Acute injection of caffeine, RO27-3225, or α-MSH produced anxiety-like behavior. Prior treatment with α-MSH, or RO27-3225 potentiated the caffeine-induced anxiety-like behavior. Subchronic treatment with HS014 increased the SI time, which was attenuated by caffeine. Chronic administration of caffeine resulted in tolerance to caffeine's anxiogenic effect, while abrupt discontinuation of the treatment produced peak anxiety-like behavior at 72 h post-withdrawal. Concurrent administration of α-MSH, or RO27-3225 with chronic caffeine delayed the development of tolerance and prevented withdrawal-induced anxiety-like behavior. Moreover, acute treatment with HS014 at 72 h post-withdrawal attenuated the anxiety-like behavior. SIGNIFICANCE α-MSH, possibly via MC4 receptor in the neuroanatomical framework of the CeA, may contribute to the acute, chronic and withdrawal actions of caffeine associated with anxiety-like behavior in the neuroanatomical framework of the CeA.
Collapse
Affiliation(s)
- Amita A Bhorkar
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440 033, Maharashtra, India
| | - Manoj P Dandekar
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440 033, Maharashtra, India
| | - Kartik T Nakhate
- Rungta College of Pharmaceutical Sciences and Research, Rungta Educational Campus, Kohka-Kurud Road, Bhilai 490 024, Chhattisgarh, India
| | - Nishikant K Subhedar
- Indian Institute of Science Education and Research (IISER), Sai Trinity Building, Sutarwadi, Pashan, Pune 411 021, Maharashtra, India
| | - Dadasaheb M Kokare
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440 033, Maharashtra, India.
| |
Collapse
|
27
|
Asan E, Steinke M, Lesch KP. Serotonergic innervation of the amygdala: targets, receptors, and implications for stress and anxiety. Histochem Cell Biol 2013; 139:785-813. [DOI: 10.1007/s00418-013-1081-1] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/02/2013] [Indexed: 01/09/2023]
|
28
|
Campos AC, de Paula Soares V, Carvalho MC, Ferreira FR, Vicente MA, Brandão ML, Zuardi AW, Zangrossi H, Guimarães FS. Involvement of serotonin-mediated neurotransmission in the dorsal periaqueductal gray matter on cannabidiol chronic effects in panic-like responses in rats. Psychopharmacology (Berl) 2013; 226:13-24. [PMID: 23007604 DOI: 10.1007/s00213-012-2878-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 09/06/2012] [Indexed: 11/30/2022]
Abstract
RATIONALE Cannabidiol (CBD) is a non-psychotomimetic constituent of Cannabis sativa plant that promotes antianxiety and anti-panic effects in animal models after acute systemic or intra-dorsal periaqueductal gray (DPAG) administration. However, the effects of CBD repeated administration, and the possible mechanisms involved, in animal models of anxiety- and panic-related responses remain poorly understood. OBJECTIVE The present study evaluates the role of the serotonergic neurotransmission within the DPAG in the modulation of escape responses of rats chronically treated with CBD. METHODS Male Wistar rats received acute or repeated (5 mg/Kg/daily/21 days) administration of CBD and were submitted to the elevated T-maze (ETM). We also investigated if CBD effects on the ETM depend on facilitation of 5-HT1A-mediated neurotransmission in the DPAG. To this latter aim, we verified if these effects would be prevented by intra-DPAG injection of the 5-HT1A receptor antagonist WAY100635 (0.37 nmol/0.2 μL). Also, we verified, by in vivo microdialysis, if CBD chronic treatment increases serotonin (5-HT) release and, by quantitative polymerase chain reaction, if there are changes in 5HT-1A or 5HT-2C mRNA expression in DPAG. RESULTS The results showed that repeated but not acute peripheral administration of CBD decreases escape responses in the ETM, suggesting a panicolytic effect. This treatment did not change 5HT-1A or 5-HT-2C receptor mRNA expression nor modify serotonin extracellular concentrations in the DPAG. CBD effects were prevented by DPAG injection of the 5-HT1A receptor antagonist. CONCLUSIONS Together, these findings suggest that repeated treatment with CBD induces anti-panic effects by acting on 5-HT1A receptors in DPAG.
Collapse
Affiliation(s)
- Alline Cristina Campos
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, 3900 Bandeirantes av., Monte Alegre, Ribeirão Preto, São Paulo, Brazil.
| | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Bailey CR, Cordell E, Sobin SM, Neumeister A. Recent progress in understanding the pathophysiology of post-traumatic stress disorder: implications for targeted pharmacological treatment. CNS Drugs 2013; 27:221-32. [PMID: 23483368 PMCID: PMC3629370 DOI: 10.1007/s40263-013-0051-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Post-traumatic stress disorder (PTSD) is a common and chronic anxiety disorder that can result after exposure to a traumatic event. Though our understanding of the aetiology of PTSD is incomplete, several neurobiological systems have been implicated in the pathophysiology and vulnerability towards developing PTSD after trauma exposure. We aimed to provide a concise review of benchmark findings in important neurobiological systems related to the aetiology and maintenance of PTSD symptomology. Specifically, we discuss functional aetiologies in the noradrenergic, serotonergic, endogenous cannabinoid and opioid systems as well as the hypothalamic-pituitary adrenal (HPA) axis. This article provides a succinct framework to appreciate the current understanding of neurobiological mechanisms related to the pathophysiology of PTSD and how these findings may impact the development of future, targeted pharmacological treatments for this debilitating disorder.
Collapse
|
30
|
Ravinder S, Burghardt NS, Brodsky R, Bauer EP, Chattarji S. A role for the extended amygdala in the fear-enhancing effects of acute selective serotonin reuptake inhibitor treatment. Transl Psychiatry 2013; 3:e209. [PMID: 23321806 PMCID: PMC3566718 DOI: 10.1038/tp.2012.137] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Selective serotonin reuptake inhibitors (SSRIs) are reported to exacerbate symptoms of anxiety when treatment is initiated. These clinical findings have been extended to animal models wherein SSRIs also potentiate anxiety and fear learning, which depend on the amygdala. Yet, little is known about the role of specific amygdalar circuits in these acute effects of SSRIs. Here, we first confirmed that a single injection of fluoxetine 1 h before auditory fear conditioning potentiated fear memory in rats. To probe the neural substrates underlying this enhancement, we analyzed the expression patterns of the immediate early gene, Arc (activity-regulated cytoskeleton-associated protein). Consistent with previous reports, fear conditioning induced Arc protein expression in the lateral and basal amygdala. However, this was not enhanced further by pre-treatment with fluoxetine. Instead, fluoxetine significantly enhanced expression of Arc in the central amygdala (CeA) and the bed nucleus of the stria terminalis (BNST). Next, we tested whether direct targeted infusions of fluoxetine into the CeA, or BNST, leads to the same fear-potentiating effect. Strikingly, direct infusion of fluoxetine into the BNST, but not the CeA, was sufficient to enhance fear memory. Moreover, this behavioral effect was also accompanied by robust Arc expression in the CeA, similar to the systemic injection. Our results identify a novel role for the BNST in the acute fear-enhancing effects of SSRIs. These findings highlight the need to look beyond the traditional focus on input nuclei of the amygdala and add to accumulating evidence implicating these microcircuits in gating fear and anxiety.
Collapse
Affiliation(s)
- S Ravinder
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - N S Burghardt
- Departments of Neuroscience, Psychiatry & Pharmacology, Columbia University, New York, NY, USA
| | - R Brodsky
- Biology Department, Barnard College, Columbia University, New York, NY, USA
| | - E P Bauer
- Biology Department, Barnard College, Columbia University, New York, NY, USA
| | - S Chattarji
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India,National Centre for Biological Sciences, GKVK Campus, Bellary Road, Bangalore 560065, India. E-mail:
| |
Collapse
|
31
|
Homberg JR. Serotonergic modulation of conditioned fear. SCIENTIFICA 2012; 2012:821549. [PMID: 24278743 PMCID: PMC3820492 DOI: 10.6064/2012/821549] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 09/26/2012] [Indexed: 06/02/2023]
Abstract
Conditioned fear plays a key role in anxiety disorders as well as depression and other neuropsychiatric conditions. Understanding how neuromodulators drive the associated learning and memory processes, including memory consolidation, retrieval/expression, and extinction (recall), is essential in the understanding of (individual differences in vulnerability to) these disorders and their treatment. The human and rodent studies I review here together reveal, amongst others, that acute selective serotonin reuptake inhibitor (SSRI) treatment facilitates fear conditioning, reduces contextual fear, and increases cued fear, chronic SSRI treatment reduces both contextual and cued fear, 5-HT1A receptors inhibit the acquisition and expression of contextual fear, 5-HT2A receptors facilitates the consolidation of cued and contextual fear, inactivation of 5-HT2C receptors facilitate the retrieval of cued fear memory, the 5-HT3 receptor mediates contextual fear, genetically induced increases in serotonin levels are associated with increased fear conditioning, impaired cued fear extinction, or impaired extinction recall, and that genetically induced 5-HT depletion increases fear conditioning and contextual fear. Several explanations are presented to reconcile seemingly paradoxical relationships between serotonin levels and conditioned fear.
Collapse
Affiliation(s)
- Judith R. Homberg
- Donders Institute for Brain, Cognition and Behaviour, Department of Cognitive Neuroscience, Radboud University Medical Centre, Geert Grooteplein 21, Route 126, 6525 EZ Nijmegen, The Netherlands
| |
Collapse
|
32
|
Li X. Using the conditioned fear stress (CFS) animal model to understand the neurobiological mechanisms and pharmacological treatment of anxiety. SHANGHAI ARCHIVES OF PSYCHIATRY 2012; 24:241-9. [PMID: 25328347 PMCID: PMC4198872 DOI: 10.3969/j.issn.1002-0829.2012.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
SUMMARY The mechanisms underlying the etiology and pathophysiology of anxiety disorders - the most prevalent class of mental disorders - remain unclear. Over the last 30 years investigators have used the animal model of conditioned fear stress (CFS) to investigate the brain structures and neurotransmitter systems involved in aversive emotional learning and memory. Recent studies have focused on the neuronal circuitry and cellular mechanisms of fearful emotional experiences. This review describes the CFS paradigm, discusses the neural circuit and neurotransmission underlying CFS, and explains the mechanism of action of pharmacological treatments of CFS. The focus of the review is on the molecular mechanisms of fear extinction, a phenomenon directly implicated in the clinical treatment of anxiety. Based on our assessment of previous work we will conclude by considering potential molecular targets for treating symptoms of anxiety and fear.
Collapse
|
33
|
Izumi T, Ohmura Y, Futami Y, Matsuzaki H, Kubo Y, Yoshida T, Yoshioka M. Effects of serotonergic terminal lesion in the amygdala on conditioned fear and innate fear in rats. Eur J Pharmacol 2012; 696:89-95. [PMID: 23036373 DOI: 10.1016/j.ejphar.2012.09.028] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Revised: 09/08/2012] [Accepted: 09/22/2012] [Indexed: 10/27/2022]
Abstract
The amygdala and the medial prefrontal cortex (mPFC) are crucial brain structures for anxiety, and it is speculated that the serotonergic neural system in these structures has an important role in regulating anxiety. In our previous study, we indicated that local injections of selective serotonin reuptake inhibitor into the amygdala attenuated anxiety-related behaviors in conditioned fear in rats. In the present study, we investigated the effects of serotonergic terminal lesions in the amygdala and in mPFC induced by local injection of 5,7-dihydroxytryptamine (5,7-DHT), on anxiety-related behaviors in conditioned fear and the elevated plus-maze test in rats. A 5,7-DHT lesion in the amygdala attenuated memory-dependent fear assessed by conditioned fear, but enhanced memory-independent fear assessed by the elevated plus-maze test. These results suggest that the role of the amygdalar serotonergic system in fear is different between memory-dependent and independent fear and, in particular, it is paradoxical that an amygdalar serotonergic lesion exerts a similar effect on memory-dependent fear to SSRI. Moreover, a serotonergic lesion in the amygdala enhanced the retrieval of extinction memory in conditioned fear; however, a serotonergic lesion in mPFC did not bring about any behavioral changes.
Collapse
Affiliation(s)
- Takeshi Izumi
- Department of Neuropharmacology, Hokkaido University Graduate School of Medicine, North 15, West 7, Sapporo 060-8638, Japan.
| | | | | | | | | | | | | |
Collapse
|
34
|
Zhang Y, Chen Q, Du F, Hu Y, Chao F, Tian M, Zhang H. Frightening music triggers rapid changes in brain monoamine receptors: a pilot PET study. J Nucl Med 2012; 53:1573-8. [PMID: 22933818 DOI: 10.2967/jnumed.112.106690] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
UNLABELLED Frightening music can rapidly arouse emotions in listeners that mimic those from actual life-threatening experiences. However, studies of the underlying mechanism for perceiving danger created by music are limited. METHODS We investigated monoamine receptor changes induced by frightening music using (11)C-N-methyl-spiperone ((11)C-NMSP) PET. Ten healthy male volunteers were included, and their psychophysiologic changes were evaluated. RESULTS Compared with the baseline condition, listening to frightening music caused a significant decrease in (11)C-NMSP in the right and left caudate nuclei, right limbic region, and right paralimbic region; a particularly significant decrease in the right anterior cingulate cortex; but an increase in the right frontal occipital and left temporal lobes of the cerebral cortex. CONCLUSION Transient fright triggers rapid changes in monoamine receptors, which decrease in the limbic and paralimbic regions but increase in the cerebral cortex.
Collapse
Affiliation(s)
- Ying Zhang
- Department of Nuclear Medicine, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China.
| | | | | | | | | | | | | |
Collapse
|
35
|
Serotonergic innervation and serotonin receptor expression of NPY-producing neurons in the rat lateral and basolateral amygdaloid nuclei. Brain Struct Funct 2012; 218:421-35. [PMID: 22527118 PMCID: PMC3580143 DOI: 10.1007/s00429-012-0406-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Accepted: 03/13/2012] [Indexed: 01/28/2023]
Abstract
Pharmacobehavioral studies in experimental animals, and imaging studies in humans, indicate that serotonergic transmission in the amygdala plays a key role in emotional processing, especially for anxiety-related stimuli. The lateral and basolateral amygdaloid nuclei receive a dense serotonergic innervation in all species studied to date. We investigated interrelations between serotonergic afferents and neuropeptide Y (NPY)-producing neurons, which are a subpopulation of inhibitory interneurons in the rat lateral and basolateral nuclei with particularly strong anxiolytic properties. Dual light microscopic immunolabeling showed numerous appositions of serotonergic afferents on NPY-immunoreactive somata. Using electron microscopy, direct membrane appositions and synaptic contacts between serotonin-containing axon terminals and NPY-immunoreactive cellular profiles were unequivocally established. Double in situ hybridization documented that more than 50 %, and about 30–40 % of NPY mRNA-producing neurons, co-expressed inhibitory 5-HT1A and excitatory 5-HT2C mRNA receptor subtype mRNA, respectively, in both nuclei with no gender differences. Triple in situ hybridization showed that individual NPY mRNA-producing interneurons co-express both 5-HT1A and 5-HT2C mRNAs. Co-expression of NPY and 5-HT3 mRNA was not observed. The results demonstrate that serotonergic afferents provide substantial innervation of NPY-producing neurons in the rat lateral and basolateral amygdaloid nuclei. Studies of serotonin receptor subtype co-expression indicate a differential impact of the serotonergic innervation on this small, but important, population of anxiolytic interneurons, and provide the basis for future studies of the circuitry underlying serotonergic modulation of emotional stimulus processing in the amygdala.
Collapse
|
36
|
Carvalho MC, Moreira CM, Zanoveli JM, Brandão ML. Central, but not basolateral, amygdala involvement in the anxiolytic-like effects of midazolam in rats in the elevated plus maze. J Psychopharmacol 2012; 26:543-54. [PMID: 21148026 DOI: 10.1177/0269881110389209] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The role of the amygdala in the mediation of fear and anxiety has been extensively investigated. However, how the amygdala functions during the organization of the anxiety-like behaviors generated in the elevated plus maze (EPM) is still under investigation. The basolateral (BLA) and the central (CeA) nuclei are the main input and output stations of the amygdala. In the present study, we ethopharmacologically analyzed the behavior of rats subjected to the EPM and the tissue content of the monoamines dopamine (DA) and serotonin (5-HT) and their metabolites in the nucleus accumbens (NAc), dorsal hippocampus (DH), and dorsal striatum (DS) of animals injected with saline or midazolam (20 and 30 nmol/0.2 µL) into the BLA or CeA. Injections of midazolam into the CeA, but not BLA, caused clear anxiolytic-like effects in the EPM. These treatments did not cause significant changes in 5-HT or DA contents in the NAc, DH, or DS of animals tested in the EPM. The data suggest that the anxiolytic-like effects of midazolam in the EPM also appear to rely on GABA-benzodiazepine mechanisms in the CeA, but not BLA, and do not appear to depend on 5-HT and DA mechanisms prevalent in limbic structures.
Collapse
Affiliation(s)
- Milene C Carvalho
- Laboratório de Psicobiologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | | | | | | |
Collapse
|
37
|
Reduced amygdala serotonin transporter binding in posttraumatic stress disorder. Biol Psychiatry 2011; 70:1033-8. [PMID: 21855859 PMCID: PMC3207037 DOI: 10.1016/j.biopsych.2011.07.003] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 06/23/2011] [Accepted: 07/01/2011] [Indexed: 11/24/2022]
Abstract
BACKGROUND The amygdala is a key site where alterations in the regulation of the serotonin transporter (5-HTT) may alter stress response. Deficient 5-HTT function and abnormal amygdala activity have been hypothesized to contribute to the pathophysiology of posttraumatic stress disorder (PTSD), but no study has evaluated the 5-HTT in humans with PTSD. On the basis of translational models, we hypothesized that patients diagnosed with PTSD would exhibit reduced amygdala 5-HTT expression as measured with positron emission tomography and the recently developed 5-HTT-selective radiotracer [(11)C]AFM. METHODS Fifteen participants with PTSD and 15 healthy control (HC) subjects without trauma history underwent a resting-state positron emission tomography scan. RESULTS [(11)C]AFM binding potential (BP(ND)) within the combined bilateral amygdala region of interest was significantly reduced in the PTSD group compared with the HC group (p = .027; 16.3% reduction), which was largely driven by the between-group difference in the left amygdala (p = .008; 20.5% reduction). Furthermore, amygdala [(11)C]AFM BP(ND) was inversely correlated with both Hamilton Rating Scale for Anxiety scores (r = -.55, p = .035) and Montgomery-Åsberg Depression Rating Scale scores (r = -.56, p = .029). CONCLUSIONS Our findings of abnormally reduced amygdala 5-HTT binding in PTSD and its association with higher anxiety and depression symptoms in PTSD patients support a translational neurobiological model of PTSD directly implicating dysregulated 5-HTT signaling within neural systems underlying threat detection and fear learning.
Collapse
|