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Deng F, Wan J, Li G, Dong H, Xia X, Wang Y, Li X, Zhuang C, Zheng Y, Liu L, Yan Y, Feng J, Zhao Y, Xie H, Li Y. Improved green and red GRAB sensors for monitoring spatiotemporal serotonin release in vivo. Nat Methods 2024; 21:692-702. [PMID: 38443508 DOI: 10.1038/s41592-024-02188-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 01/19/2024] [Indexed: 03/07/2024]
Abstract
The serotonergic system plays important roles in both physiological and pathological processes, and is a therapeutic target for many psychiatric disorders. Although several genetically encoded GFP-based serotonin (5-HT) sensors were recently developed, their sensitivities and spectral profiles are relatively limited. To overcome these limitations, we optimized green fluorescent G-protein-coupled receptor (GPCR)-activation-based 5-HT (GRAB5-HT) sensors and developed a red fluorescent GRAB5-HT sensor. These sensors exhibit excellent cell surface trafficking and high specificity, sensitivity and spatiotemporal resolution, making them suitable for monitoring 5-HT dynamics in vivo. Besides recording subcortical 5-HT release in freely moving mice, we observed both uniform and gradient 5-HT release in the mouse dorsal cortex with mesoscopic imaging. Finally, we performed dual-color imaging and observed seizure-induced waves of 5-HT release throughout the cortex following calcium and endocannabinoid waves. In summary, these 5-HT sensors can offer valuable insights regarding the serotonergic system in both health and disease.
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Affiliation(s)
- Fei Deng
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, China
| | - Jinxia Wan
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Guochuan Li
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Hui Dong
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Xiju Xia
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
- Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Yipan Wang
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Xuelin Li
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Chaowei Zhuang
- Department of Automation, Tsinghua University, Beijing, China
| | - Yu Zheng
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
- Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Laixin Liu
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
- Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Yuqi Yan
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
- Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Jiesi Feng
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Yulin Zhao
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Hao Xie
- Department of Automation, Tsinghua University, Beijing, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China.
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China.
- Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
- Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
- Chinese Institute for Brain Research, Beijing, China.
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Olivier JDA, Janssen JA, Esquivel-Franco DC, de Prêtre S, Olivier B. A new approach to 'on-demand' treatment of lifelong premature ejaculation by treatment with a combination of a 5-HT 1A receptor antagonist and SSRI in rats. Front Neurosci 2023; 17:1224959. [PMID: 37781259 PMCID: PMC10534979 DOI: 10.3389/fnins.2023.1224959] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 08/16/2023] [Indexed: 10/03/2023] Open
Abstract
Lifelong premature ejaculation (PE) in men lacks an adequate on-demand pharmacological treatment. Although selective serotonin reuptake inhibitors (SSRIs) are used for PE they only work after chronic treatment, or if used on-demand, less adequately than chronic SSRI treatment. It has been shown that the addition of a behaviorally silent 5-HT1A-receptor antagonist to an SSRI can generate acute inhibitory effects on male rat sexual behavior. Atlas987 is a selective 5-HT1A-receptor antagonist with equal potency to displace agonist and antagonist binding to pre- and post-synaptic 5-HT1A receptors in rat and human brain. To investigate whether Atlas987 together with the SSRI paroxetine, a combination called Enduro, induces acute inhibitory effects on male rat sexual behavior, we tested Enduro in Wistar rats in a dose-dependent manner. We first tested the 5-HT1A receptor antagonist Atlas987 in 8-OH-DPAT induced serotonergic behavior in rats. Second, we tested Enduro in a dose-dependent manner in male sexual behavior. Third, we tested the effective time window of Enduro's action, and lastly, we measured the plasma levels of Atlas987 and paroxetine over an 8-h period. Results showed that Enduro acutely and dose-dependently reduced the number of ejaculations and increased the ejaculation latencies. The behavioral pattern induced reflected a specific effect on sexual behavior excluding non-specific effects like sedation or sensoric-motoric disturbances. The time-window of activity of Enduro showed that this sexual inhibitory activity was at least found in a 1-4 h' time window after administration. Plasma levels showed that in this time frame both Atlas987 and paroxetine are present. In conclusion, in rats, Enduro is successful in acutely inhibiting sexual behavior. These results may be therapeutically attractive as "on demand" treatment for life-long premature ejaculation in men.
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Affiliation(s)
- Jocelien D. A. Olivier
- Neurobiology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, Netherlands
| | - Josien A. Janssen
- Neurobiology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, Netherlands
| | - Diana C. Esquivel-Franco
- Neurobiology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, Netherlands
| | | | - Berend Olivier
- Atlas Pharmaceuticals BV, Bruges, Belgium
- Psychopharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Netherlands
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, United States
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3
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Salvi PS, Shaughnessy MP, Sumigray KD, Cowles RA. Antibiotic-induced microbial depletion enhances murine small intestinal epithelial growth in a serotonin-dependent manner. Am J Physiol Gastrointest Liver Physiol 2023; 325:G80-G91. [PMID: 37158470 DOI: 10.1152/ajpgi.00113.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 01/06/2023] [Accepted: 01/28/2023] [Indexed: 05/10/2023]
Abstract
Regulation of small intestinal epithelial growth by endogenous and environmental factors is critical for intestinal homeostasis and recovery from insults. Depletion of the intestinal microbiome increases epithelial proliferation in small intestinal crypts, similar to the effects observed in animal models of serotonin potentiation. Based on prior evidence that the microbiome modulates serotonin activity, we hypothesized that microbial depletion-induced epithelial proliferation is dependent on host serotonin activity. A mouse model of antibiotic-induced microbial depletion (AIMD) was employed. Serotonin potentiation was achieved through either genetic knockout of the serotonin transporter (SERT) or pharmacological SERT inhibition, and inhibition of serotonin synthesis was achieved with para-chlorophenylalanine. AIMD and serotonin potentiation increased intestinal villus height and crypt proliferation in an additive manner, but the epithelial proliferation observed after AIMD was blocked in the absence of endogenous serotonin. Using Lgr5-EGFP-reporter mice, we evaluated intestinal stem cell (ISC) quantity and proliferation. AIMD increased the number of ISCs per crypt and ISC proliferation compared with controls, and changes in ISC number and proliferation were dependent on the presence of host serotonin. Furthermore, Western blotting demonstrated that AIMD reduced epithelial SERT protein expression compared with controls. In conclusion, host serotonin activity is necessary for microbial depletion-associated changes in villus height and ISC proliferation in crypts, and microbial depletion produces a functional serotonin-potentiated state through reduced SERT protein expression. These findings provide an understanding of how changes to the microbiome contribute to intestinal pathology and can be applied therapeutically.NEW & NOTEWORTHY Antibiotic-induced microbial depletion of the murine small intestine results in a state of potentiated serotonin activity through reduced epithelial expression of the serotonin transporter. Specifically, serotonin-dependent mechanisms lead to increased intestinal surface area and intestinal stem cell proliferation. Furthermore, the absence of endogenous serotonin leads to blunting of small intestinal villi, suggesting that serotonin signaling is required for epithelial homeostasis.
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Affiliation(s)
- Pooja S Salvi
- Division of Pediatric Surgery, Department of Surgery, Yale University School of Medicine, New Haven, Connecticut, United States
| | - Matthew P Shaughnessy
- Division of Pediatric Surgery, Department of Surgery, Yale University School of Medicine, New Haven, Connecticut, United States
| | - Kaelyn D Sumigray
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, United States
| | - Robert A Cowles
- Division of Pediatric Surgery, Department of Surgery, Yale University School of Medicine, New Haven, Connecticut, United States
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Liu G, Zhang Y, Zhang W, Wu X, Gao H, Jiang H, Dai Y, Zhang X. Novel Marker for Premature Ejaculation: Serum Leptin Level. Sex Med 2022; 10:100509. [PMID: 35398789 PMCID: PMC9177876 DOI: 10.1016/j.esxm.2022.100509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 02/25/2022] [Accepted: 03/01/2022] [Indexed: 10/26/2022] Open
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Robson DN, Li JM. A dynamical systems view of neuroethology: Uncovering stateful computation in natural behaviors. Curr Opin Neurobiol 2022; 73:102517. [PMID: 35217311 DOI: 10.1016/j.conb.2022.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 01/06/2022] [Accepted: 01/11/2022] [Indexed: 11/03/2022]
Abstract
State-dependent computation is key to cognition in both biological and artificial systems. Alan Turing recognized the power of stateful computation when he created the Turing machine with theoretically infinite computational capacity in 1936. Independently, by 1950, ethologists such as Tinbergen and Lorenz also began to implicitly embed rudimentary forms of state-dependent computation to create qualitative models of internal drives and naturally occurring animal behaviors. Here, we reformulate core ethological concepts in explicitly dynamical systems terms for stateful computation. We examine, based on a wealth of recent neural data collected during complex innate behaviors across species, the neural dynamics that determine the temporal structure of internal states. We will also discuss the degree to which the brain can be hierarchically partitioned into nested dynamical systems and the need for a multi-dimensional state-space model of the neuromodulatory system that underlies motivational and affective states.
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Affiliation(s)
- Drew N Robson
- Max Planck Institute for Biological Cybernetics, Tuebingen, Germany.
| | - Jennifer M Li
- Max Planck Institute for Biological Cybernetics, Tuebingen, Germany.
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Della Vecchia S, Marchese M, Santorelli FM, Sicca F. Kir4.1 Dysfunction in the Pathophysiology of Depression: A Systematic Review. Cells 2021; 10:2628. [PMID: 34685608 PMCID: PMC8534194 DOI: 10.3390/cells10102628] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 09/28/2021] [Accepted: 09/28/2021] [Indexed: 12/17/2022] Open
Abstract
A serotonergic dysfunction has been largely postulated as the main cause of depression, mainly due to its effective response to drugs that increase the serotonergic tone, still currently the first therapeutic line in this mood disorder. However, other dysfunctional pathomechanisms are likely involved in the disorder, and this may in part explain why some individuals with depression are resistant to serotonergic therapies. Among these, emerging evidence suggests a role for the astrocytic inward rectifier potassium channel 4.1 (Kir4.1) as an important modulator of neuronal excitability and glutamate metabolism. To discuss the relationship between Kir4.1 dysfunction and depression, a systematic review was performed according to the PRISMA statement. Searches were conducted across PubMed, Scopus, and Web of Science by two independent reviewers. Twelve studies met the inclusion criteria, analyzing Kir4.1 relationships with depression, through in vitro, in vivo, and post-mortem investigations. Increasing, yet not conclusive, evidence suggests a potential pathogenic role for Kir4.1 upregulation in depression. However, the actual contribution in the diverse subtypes of the disorder and in the comorbid conditions, for example, the epilepsy-depression comorbidity, remain elusive. Further studies are needed to better define the clinical phenotype associated with Kir4.1 dysfunction in humans and the molecular mechanisms by which it contributes to depression and implications for future treatments.
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Affiliation(s)
- Stefania Della Vecchia
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Calambrone, 56128 Pisa, Italy;
- Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy
| | - Maria Marchese
- Department of Molecular Medicine, IRCCS Stella Maris Foundation, Via dei Giacinti 2, 56128 Pisa, Italy;
| | - Filippo Maria Santorelli
- Department of Molecular Medicine, IRCCS Stella Maris Foundation, Via dei Giacinti 2, 56128 Pisa, Italy;
| | - Federico Sicca
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Calambrone, 56128 Pisa, Italy;
- Child Neuropsychiatric Unit, USL Centro Toscana, 59100 Prato, Italy
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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.
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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 ()
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Wan J, Peng W, Li X, Qian T, Song K, Zeng J, Deng F, Hao S, Feng J, Zhang P, Zhang Y, Zou J, Pan S, Shin M, Venton BJ, Zhu JJ, Jing M, Xu M, Li Y. A genetically encoded sensor for measuring serotonin dynamics. Nat Neurosci 2021; 24:746-752. [PMID: 33821000 PMCID: PMC8544647 DOI: 10.1038/s41593-021-00823-7] [Citation(s) in RCA: 132] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Accepted: 02/19/2021] [Indexed: 01/30/2023]
Abstract
Serotonin (5-HT) is a phylogenetically conserved monoamine neurotransmitter modulating important processes in the brain. To directly visualize the release of 5-HT, we developed a genetically encoded G-protein-coupled receptor (GPCR)-activation-based 5-HT (GRAB5-HT) sensor with high sensitivity, high selectivity, subsecond kinetics and subcellular resolution. GRAB5-HT detects 5-HT release in multiple physiological and pathological conditions in both flies and mice and provides new insights into the dynamics and mechanisms of 5-HT signaling.
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Affiliation(s)
- Jinxia Wan
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China,PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China
| | - Wanling Peng
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xuelin Li
- PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China
| | - Tongrui Qian
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China,PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China
| | - Kun Song
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jianzhi Zeng
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China,PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Fei Deng
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China,PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China
| | - Suyu Hao
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China,PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China
| | - Jiesi Feng
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China,PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Peng Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Yajun Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Jing Zou
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China,PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China,Department of Biological Sciences, Neurobiology Section, University of Southern California, Los Angeles, CA 90089, USA
| | - Sunlei Pan
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China,PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Mimi Shin
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - B. Jill Venton
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - J. Julius Zhu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Miao Jing
- Chinese Institute for Brain Research, Beijing 102206, China
| | - Min Xu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China,PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China,Manuscript correspondence: Yulong Li ()
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Sathianathen NJ, Hwang EC, Mian R, Bodie JA, Soubra A, Lyon JA, Sultan S, Dahm P. Selective serotonin re-uptake inhibitors for premature ejaculation in adult men. Cochrane Database Syst Rev 2021; 3:CD012799. [PMID: 33745183 PMCID: PMC8094926 DOI: 10.1002/14651858.cd012799.pub2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Premature ejaculation (PE) is a common problem among men that occurs when ejaculation happens sooner than a man or his partner would like during sex; it may cause unhappiness and relationship problems. Selective serotonin re-uptake inhibitors (SSRIs), which are most commonly used as antidepressants are being used to treat this condition. OBJECTIVES To assess the effects of SSRIs in the treatment of PE in adult men. SEARCH METHODS We performed a comprehensive search using multiple databases (the Cochrane Library, MEDLINE, Embase, Scopus, CINAHL), clinical trial registries, conference proceedings, and other sources of grey literature, up to 1 May 2020. We applied no restrictions on publication language or status. SELECTION CRITERIA We included only randomized controlled clinical trials (parallel group and cross-over trials) in which men with PE were administered SSRIs or placebo. We also considered 'no treatment' to be an eligible comparator but did not find any relevant studies. DATA COLLECTION AND ANALYSIS Two review authors independently classified and abstracted data from the included studies. Primary outcomes were participant-perceived change with treatment, satisfaction with intercourse and study withdrawal due to adverse events. Secondary outcomes included self-perceived control over ejaculation, participant distress about PE, adverse events and intravaginal ejaculatory latency time (IELT). We performed statistical analyses using a random-effects model. We rated the certainty of evidence according to GRADE. MAIN RESULTS We identified 31 studies in which 8254 participants were randomized to receiving either SSRIs or placebo. Primary outcomes: SSRI treatment probably improves self-perceived PE symptoms (defined as a rating of 'better' or 'much better') compared to placebo (risk ratio (RR) 1.92, 95% confidence interval (CI) 1.66 to 2.23; moderate-certainty evidence). Based on 220 participants per 1000 reporting improvement with placebo, this corresponds to 202 more men per 1000 (95% CI 145 more to 270 more) with improved symptoms with SSRIs. SSRI treatment probably improves satisfaction with intercourse compared to placebo (defined as a rating of 'good' or 'very good'; RR 1.63, 95% CI 1.42 to 1.87; moderate-certainty evidence). Based on 278 participants per 1000 reporting improved satisfaction with placebo, this corresponds to 175 more (117 more to 242 more) per 1000 men with greater satisfaction with intercourse with SSRIs. SSRI treatment may increase treatment cessations due to adverse events compared to placebo (RR 3.80, 95% CI 2.61 to 5.51; low-certainty evidence). Based 11 study withdrawals per 1000 participants with placebo, this corresponds to 30 more men per 1000 (95% CI 17 more to 49 more) ceasing treatment due to adverse events with SSRIs. Secondary outcomes: SSRI treatment likely improve participants' self-perceived control over ejaculation (defined as rating of 'good' or 'very good') compared to placebo (RR 2.29, 95% CI 1.72 to 3.05; moderate-certainty evidence). Assuming 132 per 1000 participants perceived at least good control, this corresponds to 170 more (95 more to 270 more) reporting at least good control with SSRIs. SSRI probably lessens distress (defined as rating of 'a little bit' or 'not at all') about PE (RR 1.54, 95% CI 1.26 to 1.88; moderate-certainty evidence). Based on 353 per 1000 participants reporting low levels of distress, this corresponds to 191 more men (92 more to 311 more) per 1000 reporting low levels of distress with SSRIs. SSRI treatment probably increases adverse events compared to placebo (RR 1.71, 95% CI 1.48 to 1.99; moderate-certainty evidence). Based on 243 adverse events per 1000 among men receiving placebo, this corresponds to 173 more (117 more to 241 more) men having an adverse event with SSRIs. SSRI treatment may increase IELT compared to placebo (mean difference (MD) 3.09 minutes longer, 95% CI 1.94 longer to 4.25 longer; low-certainty evidence). AUTHORS' CONCLUSIONS SSRI treatment for PE appears to substantially improve a number of outcomes of direct patient importance such as symptom improvement, satisfaction with intercourse and perceived control over ejaculation when compared to placebo. Undesirable effects are a small increase in treatment withdrawals due to adverse events as well as substantially increased adverse event rates. Issues affecting the certainty of evidence of outcomes were study limitations and imprecision.
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Affiliation(s)
| | - Eu Chang Hwang
- Department of Urology, Chonnam National University Medical School, Chonnam National University Hwasun Hospital, Hwasun, Korea, South
| | - Ruma Mian
- Department of Urology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Joshua A Bodie
- Department of Urology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Ayman Soubra
- Department of Urology, University of Minnesota, Minneapolis, Minnesota, USA
- Urology Section, Minneapolis VA Health Care System, Minneapolis, Minnesota, USA
| | - Jennifer A Lyon
- Library Services, Children's Mercy Hospital, Kansas City, Missouri, USA
| | - Shahnaz Sultan
- Gastroenterology Section III-D, Minneapolis VA Health Care System, Minneapolis, Minnesota, USA
| | - Philipp Dahm
- Urology Section, Minneapolis VA Health Care System, Minneapolis, Minnesota, USA
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Delcourte S, Etievant A, Haddjeri N. Role of central serotonin and noradrenaline interactions in the antidepressants' action: Electrophysiological and neurochemical evidence. PROGRESS IN BRAIN RESEARCH 2021; 259:7-81. [PMID: 33541681 DOI: 10.1016/bs.pbr.2021.01.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The development of antidepressant drugs, in the last 6 decades, has been associated with theories based on a deficiency of serotonin (5-HT) and/or noradrenaline (NA) systems. Although the pathophysiology of major depression (MD) is not fully understood, numerous investigations have suggested that treatments with various classes of antidepressant drugs may lead to an enhanced 5-HT and/or adapted NA neurotransmissions. In this review, particular morpho-physiological aspects of these systems are first considered. Second, principal features of central 5-HT/NA interactions are examined. In this regard, the effects of the acute and sustained antidepressant administrations on these systems are discussed. Finally, future directions including novel therapeutic strategies are proposed.
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Affiliation(s)
- Sarah Delcourte
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
| | - Adeline Etievant
- Integrative and Clinical Neurosciences EA481, University of Bourgogne Franche-Comté, Besançon, France
| | - Nasser Haddjeri
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France.
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11
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Näslund J, Studer E, Nilsson S, Eriksson E. Expression of 22 serotonin-related genes in rat brain after sub-acute serotonin depletion or reuptake inhibition. Acta Neuropsychiatr 2020; 32:1-7. [PMID: 32063244 PMCID: PMC7282867 DOI: 10.1017/neu.2020.9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 01/29/2020] [Accepted: 02/03/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Although the assessment of expression of serotonin-related genes in experimental animals has become a common strategy to shed light on variations in brain serotonergic function, it remains largely unknown to what extent the manipulation of serotonin levels causes detectable changes in gene expression. We therefore chose to investigate how sub-acute depletion or elevation of brain serotonin influences the expression of a number of serotonin-related genes in six brain areas. METHODS Male Wistar rats were administered a serotonin synthesis inhibitor, para-chlorophenylalanine (p-CPA), or a serotonin reuptake inhibitor, paroxetine, for 3 days and then sacrificed. The expression of a number of serotonin-related genes in the raphe nuclei, hypothalamus, amygdala, striatum, hippocampus and prefrontal cortex was investigated using real-time quantitative PCR (rt-qPCR). RESULTS While most of the studied genes were uninfluenced by paroxetine treatment, we could observe a robust downregulation of tryptophan hydroxylase-2 in the brain region where the serotonergic cell bodies reside, that is, the raphe nuclei. p-CPA induced a significant increase in the expression of Htr1b and Htr2a in amygdala and of Htr2c in the striatum and a marked reduction in the expression of Htr6 in prefrontal cortex; it also enhanced the expression of the brain-derived neurotrophic factor (Bdnf) in raphe and hippocampus. CONCLUSION With some notable exceptions, the expression of most of the studied genes is left unchanged by short-term modulation of extracellular levels of serotonin.
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Affiliation(s)
- Jakob Näslund
- Department of Pharmacology, Institute of Neuroscience and Physiology at the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Erik Studer
- Department of Pharmacology, Institute of Neuroscience and Physiology at the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Staffan Nilsson
- Division of Applied Mathematics and Statistics, Department of Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden
| | - Elias Eriksson
- Department of Pharmacology, Institute of Neuroscience and Physiology at the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Jeong S, Yang D, Beyene AG, Del Bonis-O’Donnell JT, Gest AMM, Navarro N, Sun X, Landry MP. High-throughput evolution of near-infrared serotonin nanosensors. SCIENCE ADVANCES 2019; 5:eaay3771. [PMID: 31897432 PMCID: PMC6920020 DOI: 10.1126/sciadv.aay3771] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 10/30/2019] [Indexed: 05/11/2023]
Abstract
Imaging neuromodulation with synthetic probes is an emerging technology for studying neurotransmission. However, most synthetic probes are developed through conjugation of fluorescent signal transducers to preexisting recognition moieties such as antibodies or receptors. We introduce a generic platform to evolve synthetic molecular recognition on the surface of near-infrared fluorescent single-wall carbon nanotube (SWCNT) signal transducers. We demonstrate evolution of molecular recognition toward neuromodulator serotonin generated from large libraries of ~6.9 × 1010 unique ssDNA sequences conjugated to SWCNTs. This probe is reversible and produces a ~200% fluorescence enhancement upon exposure to serotonin with a K d = 6.3 μM, and shows selective responsivity over serotonin analogs, metabolites, and receptor-targeting drugs. Furthermore, this probe remains responsive and reversible upon repeat exposure to exogenous serotonin in the extracellular space of acute brain slices. Our results suggest that evolution of nanosensors could be generically implemented to develop other neuromodulator probes with synthetic molecular recognition.
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Affiliation(s)
- Sanghwa Jeong
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Darwin Yang
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Abraham G. Beyene
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | | | - Anneliese M. M. Gest
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Nicole Navarro
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Xiaoqi Sun
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Markita P. Landry
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
- Innovative Genomics Institute (IGI), Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, QB3, University of California, Berkeley, Berkeley, CA 94720, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
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Coccaro EF, Lee RJ. 5-HT 2c agonist, lorcaserin, reduces aggressive responding in intermittent explosive disorder: A pilot study. Hum Psychopharmacol 2019; 34:e2714. [PMID: 31774584 DOI: 10.1002/hup.2714] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 09/04/2019] [Accepted: 09/25/2019] [Indexed: 11/05/2022]
Abstract
RATIONALE Impulsive aggressive behavior is associated with reduced central function of serotonin (5-HT). Although selective serotonin reuptake inhibitors can reduce such behaviors, many with history of impulsive aggression do not respond adequately to selective serotonin reuptake inhibitors and may require treatment with a direct 5-HT agonist. OBJECTIVES To test the hypothesis that pretreatment with the selective 5-HT2c agonist, lorcaserin, can reduce aggressive responding in impulsively aggressive individuals. METHODS Ten male and female adults were given lorcaserin (20 mg), or a matching placebo, in random order, on 2 days separated by at least 1 week. The Taylor aggression paradigm was used to assess aggressive responding, which was represented by mean shock setting administered to an opponent and by frequency of setting high and extreme shock levels to the opponent. RESULTS Compared with placebo, lorcaserin attenuated provoked, but not unprovoked, aggression during the Taylor aggression paradigm. This was manifest by reduction in the frequency of selecting high and extreme levels of shock against the opponent. CONCLUSION Lorcaserin may possess anti-aggressive properties that could prove useful in the treatment of impulsive aggressive behavior in human subjects. These data, thus, provide a rationale for a follow-up randomized clinical trial of lorcaserin in individuals with prominent histories of impulsive aggressive behavior.
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Affiliation(s)
- Emil F Coccaro
- Clinical Neuroscience Research Unit, Department of Psychiatry and Behavioral Neuroscience, Pritzker School of Medicine, The University of Chicago, Chicago, Illinois
| | - Royce J Lee
- Clinical Neuroscience Research Unit, Department of Psychiatry and Behavioral Neuroscience, Pritzker School of Medicine, The University of Chicago, Chicago, Illinois
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Tritschler L, Gaillard R, Gardier AM, David DJ, Guilloux JP. [Consequences of the monoaminergic systems cross-talk in the antidepressant activity]. Encephale 2018; 44:264-273. [PMID: 29801770 DOI: 10.1016/j.encep.2018.05.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 04/30/2018] [Indexed: 12/27/2022]
Abstract
Selective serotonin reuptake inhibitors (SSRIs) are the most prescribed antidepressant treatment for treat major depressive disorders. Despite their effectiveness, only 30% of SSRI-treated patients reach remission of depressive symptoms. SSRIs by inhibiting the serotonin transporter present some limits with residual symptoms. Increasing not only serotonin but also norepinephrine and dopamine levels in limbic areas seems to improve remission. Anatomical relationships across serotoninergic, dopaminergic and noradrenergic systems suggest tight reciprocal regulations among them. This review attempts to present, from acute to chronic administration the consequences of SSRI administration on monoaminergic neurotransmission. The serotonin neurons located in the raphe nucleus (RN) are connected to the locus coeruleus (locus coeruleus), the key structure of norepinephrine synthesis, through GABAergic-inhibiting interneurons. Activation of the 5-HT2A receptors expressed on GABAergic interneurons following SERT-inhibition induces an increase in serotonin leading to inhibitory effect on NE release. Similarly, the serotonin neurons exert negative regulation on dopaminergic neurons from the ventral tegmental area (VTA) through a GABAergic interneuron. These interneurons express the 5-HT2C and 5-HT3 receptors inducing an inhibitory effect of 5-HT on DA release. Positive reciprocal connections are also observed through direct projections from the locus coeruleus to the RN and from the VTA to the RN through α1 and D2 receptors respectively, both stimulating the serotoninergic activity. Acute SSRI treatment induces only a slight increase in 5-HT levels in limbic areas due to the activation of presynaptic 5-HT1A and 5-HT1B autoreceptors counteracting the effects of the transporter blockade. No change in NE levels and a small decrease in the dopaminergic neurotransmission is also observed. These weak changes in monoamine in the limbic areas after acute SSRI treatment seems to be one of key point involved in the onset of action. Following desensitization of the 5-HT1A and 5-HT1B autoreceptors, chronic SSRI treatment induces a large increase in the 5-HT neurotransmission. Changes in 5-HT levels at the limbic areas results in a decrease in NE transmission and an increase in DA transmission through an increase in the post-synaptic D2 receptors sensitivity and not from a change in DA levels, which is mainly due to a desensitization of the 5-HT2A receptor. The observed decrease of NE neurotransmission could explain some limits of the SSRI therapy and the interest to activate NE system for producing more robust effects. On the other hand, the D2 sensitization, especially in the nucleus accumbens, stimulates the motivation behavior as well as remission of anhedonia considering the major role of DA release in this structure. Finally, we need to take into account the key role of each monoaminergic neurotransmission to reach remission. Targeting only one system will limit the therapeutic effectiveness. Clinical evidences, including the STAR*D studies, confirmed this by an increase of the remission rate following the mobilization of several monoaminergic transmissions. However, these combinations cannot constitute first line of treatment considering the observed increase of side effects. Such an approach should be adapted to each patient in regard to its particular symptoms as well as clinical history. The next generation of antidepressant therapy will need to take into consideration the interconnections and the interrelation between the monoaminergic systems.
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Affiliation(s)
- L Tritschler
- CESP, Inserm UMRS1178, faculté de pharmacie, université Paris-Saclay, université Paris-Sud, 92296 Chatenay-Malabry, France
| | - R Gaillard
- Inserm UMR 894, centre de psychiatrie & neurosciences, CNRS GDR 3557, institut de psychiatrie, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France; Service hospitalo-universitaire, centre hospitalier Sainte-Anne, 75015 Paris, France
| | - A M Gardier
- CESP, Inserm UMRS1178, faculté de pharmacie, université Paris-Saclay, université Paris-Sud, 92296 Chatenay-Malabry, France
| | - D J David
- CESP, Inserm UMRS1178, faculté de pharmacie, université Paris-Saclay, université Paris-Sud, 92296 Chatenay-Malabry, France.
| | - J-P Guilloux
- CESP, Inserm UMRS1178, faculté de pharmacie, université Paris-Saclay, université Paris-Sud, 92296 Chatenay-Malabry, France.
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15
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Male rats with same-sex preference show higher immobility in the forced swim test, but similar effects of fluoxetine and desipramine than males that prefer females. Pharmacol Biochem Behav 2018; 171:39-45. [PMID: 29807066 DOI: 10.1016/j.pbb.2018.05.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 05/24/2018] [Accepted: 05/25/2018] [Indexed: 12/13/2022]
Abstract
Sex preference in male rats is partly determined by the organizational action of estradiol. Thus, several paradigms have used aromatase inhibitors to manipulate sex preference. We recently showed that a subpopulation of male rats prenatally treated with letrozole (0.56 μg/kg, G10-G22), a non-steroidal third generation aromatase inhibitor, had same-sex preference, female sexual behavior (including lordosis and proceptivity) and penile erections when exposed to other males. These males, in addition, displayed high levels of experimental anxiety in the plus maze test and were insensitive to the anxiogenic-like acute effect of FLX (10 mg/kg). The two main purposes of the present work were: a) to study the behavioral profile of males displaying same-sex preference in the forced swim test (FST), and b) to analyze if the antidepressant-like effect of the subchronic treatment with FLX (10 mg/kg, 3 times) or desipramine (DMI, 10 mg/kg, 3 times) vary according to sex preference. Males treated prenatally with letrozole with same-sex preference showed more immobility and less active behaviors (swimming and climbing) in the FST than males with female preference. Subchronic treatment with FLX and DMI reduced immobility when compared to saline controls, while FLX increased swimming and DMI increased climbing behavior. Treatments were equally effective in males with preference for other males and those that preferred females. These results indicate that an association exists between prenatal letrozole treatment, same-sex preference and immobility in the FST.
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Selvaraj S, Walker C, Arnone D, Cao B, Faulkner P, Cowen PJ, Roiser JP, Howes O. Effect of Citalopram on Emotion Processing in Humans: A Combined 5-HT 1A [ 11C]CUMI-101 PET and Functional MRI Study. Neuropsychopharmacology 2018; 43:655-664. [PMID: 28776580 PMCID: PMC5693328 DOI: 10.1038/npp.2017.166] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 07/18/2017] [Accepted: 08/01/2017] [Indexed: 12/21/2022]
Abstract
A subset of patients started on a selective serotonin reuptake inhibitor (SSRI) initially experience increased anxiety, which can lead to early discontinuation before therapeutic effects are manifest. The neural basis of this early SSRI effect is not known. Presynaptic dorsal raphe neuron (DRN) 5-HT1A receptors are known to have a critical role in affect processing. Thus we investigated the effect of acute citalopram on emotional processing and the relationship between DRN 5-HT1A receptor availability and amygdala reactivity. Thirteen (mean age 48±9 years) healthy male subjects received either a saline or citalopram infusion intravenously (10 mg over 30 min) on separate occasions in a single-blind, random order, crossover design. On each occasion, participants underwent a block design face-emotion processing task during fMRI known to activate the amygdala. Ten subjects also completed a positron emission tomography (PET) scan to quantify DRN 5-HT1A availability using [11C]CUMI-101. Citalopram infusion when compared with saline resulted in a significantly increased bilateral amygdala responses to fearful vs neutral faces (left p=0.025; right p=0.038 FWE-corrected). DRN [11C]CUMI-101 availability significantly positively correlated with the effect of citalopram on the left amygdala response to fearful faces (Z=2.51, p=0.027) and right amygdala response to happy faces (Z=2.33, p=0.032). Our findings indicate that the initial effect of SSRI treatment is to alter processing of aversive stimuli and that this is linked to DRN 5-HT1A receptors in line with evidence that 5-HT1A receptors have a role in mediating emotional processing.
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Affiliation(s)
- Sudhakar Selvaraj
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center at Houston, Houston, TX, USA,Medical Research Council London Institute of Medical Sciences, Hammersmith Hospital, London, UK,Department of Psychiatry and Behavioral Sciences, The University of Texas Health Science Center at Houston, Biomedical and Behavioral Sciences Building (BBSB), 1941 East Road, Suite 3208 Houston, TX 77054, USA, Tel: +1 713 486 2500, Fax: +1 713 486 2553, E-mail:
| | - Chris Walker
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Danilo Arnone
- Institute of Psychiatry, King’s College London, Centre for Affective Disorders, London, UK,IoPPN, King’s College London, Institute of Psychiatry, Psychosis Studies, London, UK
| | - Bo Cao
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Paul Faulkner
- Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA, USA
| | - Philip J Cowen
- Department of Psychiatry, University of Oxford, Oxford, UK
| | - Jonathan P Roiser
- Institute of Cognitive Neuroscience, University College London, London, UK
| | - Oliver Howes
- Medical Research Council London Institute of Medical Sciences, Hammersmith Hospital, London, UK,IoPPN, King’s College London, Institute of Psychiatry, Psychosis Studies, London, UK,Institute of Clinical Sciences, Imperial College, Hammersmith Hospital, London, UK
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17
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Kim YK, Jeon SW. Neuroinflammation and the Immune-Kynurenine Pathway in Anxiety Disorders. Curr Neuropharmacol 2018; 16:574-582. [PMID: 28901278 PMCID: PMC5997870 DOI: 10.2174/1570159x15666170913110426] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 07/10/2017] [Accepted: 08/16/2017] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Recently, neuroinflammation and the immune-kynurenine pathway have received increased attention in the psychoimmunology field of major depressive disorder (MDD), while studies related to anxiety disorders have been very limited. OBJECTIVE This study reviewed possible mechanisms by which stress or inflammation modulate anxiety through tryptophan metabolism and the kynurenine pathway. METHODS Relevant literature was identified through a search of MEDLINE via PubMed. RESULTS Accumulating evidence has indicated the modulatory effects of the immune-kynurenine pathway on anxiety. The tryptophan catabolites (TRYCATs) in the kynurenine pathway imbalanced by stress or inflammation induce serotonin and melatonin deficiency, making anxiety reactions more sensitive. In addition, TRYCATs cause or sustain anxiety by acting as endogenous anxiogens or anxiolytics, an NMDA agonist or antagonist, or a free radical generator. CONCLUSION We hope that our understanding of the psychoimmunological mechanisms of anxiety will be expanded and anxiety-related studies will receive greater attention.
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Affiliation(s)
| | - Sang Won Jeon
- Address correspondence to this author at the Department of Psychiatry, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, 29 Saemunan-ro, Jongno-gu, Seoul 03181, Republic of Korea; Tel: +82-2-2001-2073; Fax: +82-2-2001-2211; E-mail:
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18
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Raffa RB, Pergolizzi JV, Taylor R. The rapid‐onset antidepressant effect of ketamine: More surprises? J Clin Pharm Ther 2017; 43:308-311. [DOI: 10.1111/jcpt.12656] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 11/07/2017] [Indexed: 12/28/2022]
Affiliation(s)
- R. B. Raffa
- University of Arizona College of Pharmacy Tucson AZ USA
- Temple University School of Pharmacy Philadelphia PA USA
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Jørgensen LM, Weikop P, Villadsen J, Visnapuu T, Ettrup A, Hansen HD, Baandrup AO, Andersen FL, Bjarkam CR, Thomsen C, Jespersen B, Knudsen GM. Cerebral 5-HT release correlates with [ 11C]Cimbi36 PET measures of 5-HT2A receptor occupancy in the pig brain. J Cereb Blood Flow Metab 2017; 37:425-434. [PMID: 26825776 PMCID: PMC5381441 DOI: 10.1177/0271678x16629483] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Positron emission tomography (PET) can, when used with appropriate radioligands, non-invasively generate temporal and spatial information about acute changes in brain neurotransmitter systems. We for the first time evaluate the novel 5-HT2A receptor agonist PET radioligand, [11C]Cimbi-36, for its sensitivity to detect changes in endogenous cerebral 5-HT levels, as induced by different pharmacological challenges. To enable a direct translation of PET imaging data to changes in brain 5-HT levels, we calibrated the [11C]Cimbi-36 PET signal in the pig brain by simultaneous measurements of extracellular 5-HT levels with microdialysis and [11C]Cimbi-36 PET after various acute interventions (saline, citalopram, citalopram + pindolol, fenfluramine). In a subset of pigs, para-chlorophenylalanine pretreatment was given to deplete cerebral 5-HT. The interventions increased the cerebral extracellular 5-HT levels to 2-11 times baseline, with fenfluramine being the most potent pharmacological enhancer of 5-HT release, and induced a varying degree of decline in [11C]Cimbi-36 binding in the brain, consistent with the occupancy competition model. The observed correlation between changes in the extracellular 5-HT level in the pig brain and the 5-HT2A receptor occupancy indicates that [11C]Cimbi-36 binding is sensitive to changes in endogenous 5-HT levels, although only detectable with PET when the 5-HT release is sufficiently high.
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Affiliation(s)
- Louise M Jørgensen
- 1 Neurobiology Research Unit, Rigshospitalet, Copenhagen, Denmark.,2 Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Pia Weikop
- 3 The Laboratory of Neuropsychiatry, Department of Neuroscience and Pharmacology, University of Copenhagen, Denmark.,4 Psychiatric Centre Copenhagen, University of Copenhagen, Denmark
| | - Jonas Villadsen
- 1 Neurobiology Research Unit, Rigshospitalet, Copenhagen, Denmark
| | - Tanel Visnapuu
- 3 The Laboratory of Neuropsychiatry, Department of Neuroscience and Pharmacology, University of Copenhagen, Denmark.,5 Center for Excellence in Translational Medicine, University of Tartu, Estonia
| | - Anders Ettrup
- 1 Neurobiology Research Unit, Rigshospitalet, Copenhagen, Denmark
| | - Hanne D Hansen
- 1 Neurobiology Research Unit, Rigshospitalet, Copenhagen, Denmark
| | - Anders O Baandrup
- 6 Research Center for Advanced Imaging, Hospital of Køge and Roskilde, Roskilde, Denmark
| | | | | | - Carsten Thomsen
- 2 Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.,9 Department of Radiology, Rigshospitalet, Copenhagen, Denmark
| | - Bo Jespersen
- 10 Department of Neurosurgery, Rigshospitalet, Copenhagen, Denmark
| | - Gitte M Knudsen
- 1 Neurobiology Research Unit, Rigshospitalet, Copenhagen, Denmark.,2 Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
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Farhan M, Haleem DJ. Anxiolytic profile of fluoxetine as monitored following repeated administration in animal rat model of chronic mild stress. Saudi Pharm J 2016; 24:571-578. [PMID: 27752230 PMCID: PMC5059824 DOI: 10.1016/j.jsps.2015.03.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 03/13/2015] [Indexed: 11/30/2022] Open
Abstract
Background: Fluoxetine, a selective serotonin re-uptake inhibitor (SSRI), has been proposed to be more effective as an antidepressive drug as compared to other SSRIs. After chronic SSRI administration, the increase in synaptic levels of 5-HT leads to desensitization of somatodentritic 5-HT autoreceptors in the raphe nuclei. Chronic stress may alter behavioral, neurochemical and physiological responses to drug challenges and novel stressors. Methods: Twenty four male rats were used in this study. Animals of CMS group were exposed to CMS. Animals of stressed and unstressed group were administrated with fluoxetine at dose of 1.0 mg/kg s well as 5.0 mg/kg repeatedly for 07 days 1 h before exposed to CMS. The objective of the present study was to evaluate that repeated treatment with fluoxetine could attenuate CMS-induced behavioral deficits. Results: Treatment with fluoxetine attenuated CMS-induced behavioral deficits. Fluoxetine administration induced hypophagia in unstressed as well as CMS rats. Acute and repeated administration of fluoxetine increased motor activity in familiar environment but only repeated administration increased exploratory activity in open field. Anxiolytic effects of fluoxetine were greater in unstressed rats. These anxiolytic effects were produced as result of repeated administration not on acute administration of fluoxetine at 1.0 mg/kg as well as 5.0 mg/kg. Conclusion: The present study demonstrated that CMS exposure resulted into behavioral deficits and produced depressive-like symptoms. Fluoxetine, an SSRI, administration attenuated behavioral deficits induced by CMS. Anxiolytic effects of repeated fluoxetine administration were greater in unstressed than CMS animals.
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Affiliation(s)
- Muhammad Farhan
- Neurochemistry and Biochemical Neuropharmacology Research Unit, Department of Biochemistry, University of Karachi, Karachi, Pakistan
| | - Darakshan Jabeen Haleem
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
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21
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Kalogiannis M, Delikatny EJ, Jeitner TM. Serotonin as a putative scavenger of hypohalous acid in the brain. Biochim Biophys Acta Mol Basis Dis 2015; 1862:651-661. [PMID: 26699077 DOI: 10.1016/j.bbadis.2015.12.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 12/04/2015] [Accepted: 12/11/2015] [Indexed: 12/31/2022]
Abstract
Neurodegenerative disorders represent the culmination of numerous insults including oxidative stress. The long etiology of most of these disorders suggests that lessening the effects of one or more of the insults could significantly delay disease onset. Antioxidants have been tested as possible therapeutics for neurodegenerative disorders, but with little success. Here we report that serotonin acts as a scavenger of hypochlorous acid (HOCl) in the brain. Serotonin was shown to prevent the oxidation of 2-thio-5-nitrobenzoate by HOCl in a biphasic manner. The first phase was a partial scavenging that occurred at concentrations of serotonin that exceeded those of HOCl. (1)H-NMR studies indicated that HOCl chlorinates both the aryl and akyl nitrogen atoms of serotonin. Thus, the oxidation of 2-thio-5-nitrobenzoate that occurred during the first phase of scavenging is likely due to the formation of serotonergic chloramines. A second phase of scavenging occurred at concentrations of HOCl that exceeded those of serotonin. Under these conditions, the chlorinated serotonin polymerized and formed inert aggregates. Serotonin was further shown to prevent the loss of cells and cellular α-ketoglutarate dehydrogenase complex activity caused by HOCl. Extracellular concentrations of serotonin in the brain can be elevated with selective serotonin reuptake inhibitors and suggests that such compounds could be used to increase the cerebral antioxidant capacity. Acute administration of selective serotonin reuptake inhibitors to mice treated with endotoxin partially mitigated sickness behavior and protein chlorination in the brain. These observations suggest that serotonin may act to suppress chlorinative stress in the brain.
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Affiliation(s)
- Mike Kalogiannis
- Department of Neurosciences, Winthrop University Hospital, 222 Station Plaza, Mineola, NY 11501, USA.
| | - E James Delikatny
- Department of Radiology, University of Pennsylvania, 317 Anatomy Chemistry Building, 3620 Hamilton Walk, Pennsylvania, PA 19104, USA.
| | - Thomas M Jeitner
- Department of Neurosciences, Winthrop University Hospital, 222 Station Plaza, Mineola, NY 11501, USA; Department of Biochemistry and Molecular Biology, New York Medical College, Basic Sciences, 15 Dana Road, Valhalla, NY 10595, USA.
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Delgermurun D, Ito S, Ohta T, Yamaguchi S, Otsuguro KI. Endogenous 5-HT outflow from chicken aorta by 5-HT uptake inhibitors and amphetamine derivatives. J Vet Med Sci 2015; 78:71-6. [PMID: 26321443 PMCID: PMC4751119 DOI: 10.1292/jvms.15-0146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Chemoreceptor cells aggregating in clusters in the chicken thoracic aorta
contain 5-hydroxytryptamine (5-HT) and have voltage-dependent ion channels and nicotinic
acetylcholine receptors, which are characteristics typically associated with neurons. The
aim of the present study was to investigate the effects of 5-HT uptake inhibitors,
fluvoxamine, fluoxetine and clomipramine (CLM), and amphetamine derivatives,
p-chloroamphetamine (PCA) and methamphetamine (MET), on endogenous 5-HT
outflow from the isolated chick thoracic aorta in vitro. 5-HT was
measured by using a HPLC system with electrochemical detection. The amphetamine
derivatives and 5-HT uptake inhibitors caused concentration-dependent increases in
endogenous 5-HT outflow. PCA was about ten times more effective in eliciting 5-HT outflow
than MET. The 5-HT uptake inhibitors examined had similar potency for 5-HT outflow. PCA
and CLM increased 5-HT outflow in a temperature-dependent manner. The outflow of 5-HT
induced by PCA or 5-HT uptake inhibitors was independent of extracellular Ca2+
concentration. The 5-HT outflow induced by CLM, but not that by PCA, was dependent on the
extracellular NaCl concentration. These results suggest that the 5-HT uptake system of
5-HT-containing chemoreceptor cells in the chicken thoracic aorta has characteristics
similar to those of 5-HT-containing neurons in the mammalian central nervous system
(CNS).
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Affiliation(s)
- Dugar Delgermurun
- Laboratory of Pharmacology, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan
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Tao R, Shokry IM, Callanan JJ, Adams HD, Ma Z. Mechanisms and environmental factors that underlying the intensification of 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy)-induced serotonin syndrome in rats. Psychopharmacology (Berl) 2015; 232:1245-60. [PMID: 25300903 PMCID: PMC4361258 DOI: 10.1007/s00213-014-3759-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 09/23/2014] [Indexed: 01/08/2023]
Abstract
RATIONALE Illicit use of 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy) may cause a mild or severe form of the serotonin syndrome. The syndrome intensity is not just influenced by drug doses but also by environmental factors. OBJECTIVES Warm environmental temperatures and physical activity are features of raves. The purpose of this study was to assess how these two factors can potentially intensify the syndrome. METHODS Rats were administered MDMA at doses of 0.3, 1, or 3 mg/kg and examined in the absence or presence of warm temperature and physical activity. The syndrome intensity was estimated by visual scoring for behavioral syndrome and also instrumentally measuring changes in symptoms of the syndrome. RESULTS Our results showed that MDMA at 3 mg/kg, but not 0.3 or 1 mg/kg, caused a mild serotonin syndrome in rats. Each environmental factor alone moderately intensified the syndrome. When the two factors were combined, the intensification became more severe than each factor alone highlighting a synergistic effect. This intensification was blocked by the 5-HT2A receptor antagonist M100907, competitive N-methyl-D-aspartic acid (NMDA) receptor antagonist CGS19755, autonomic ganglionic blocker hexamethonium, and the benzodiazepine-GABAA receptor agonist midazolam but not by the 5-HT1A receptor antagonist WAY100635 or nicotinic receptor antagonist methyllycaconitine. CONCLUSIONS Our data suggest that, in the absence of environmental factors, the MDMA-induced syndrome is mainly mediated through the serotonergic transmission (5-hydroxytryptamine (5HT)-dependent mechanism) and therefore is relatively mild. Warm temperature and physical activity facilitate serotonergic and other neural systems such as glutamatergic and autonomic transmissions, resulting in intensification of the syndrome (non-5HT mechanisms).
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Affiliation(s)
- Rui Tao
- Charles E. Schmidt College of Medicine, Florida Atlantic University, 777 Glades Road, Boca Raton, FL, 33431, USA,
| | - Ibrahim M. Shokry
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida, USA, School of Veterinary Medicine, Ross University, St. Kitts, West Indies
| | - John J. Callanan
- School of Veterinary Medicine, Ross University, St. Kitts, West Indies
| | - H. Daniel Adams
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida, USA
| | - Zhiyuan Ma
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida, USA
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Finnema SJ, Scheinin M, Shahid M, Lehto J, Borroni E, Bang-Andersen B, Sallinen J, Wong E, Farde L, Halldin C, Grimwood S. Application of cross-species PET imaging to assess neurotransmitter release in brain. Psychopharmacology (Berl) 2015; 232:4129-57. [PMID: 25921033 PMCID: PMC4600473 DOI: 10.1007/s00213-015-3938-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 04/09/2015] [Indexed: 01/03/2023]
Abstract
RATIONALE This review attempts to summarize the current status in relation to the use of positron emission tomography (PET) imaging in the assessment of synaptic concentrations of endogenous mediators in the living brain. OBJECTIVES Although PET radioligands are now available for more than 40 CNS targets, at the initiation of the Innovative Medicines Initiative (IMI) "Novel Methods leading to New Medications in Depression and Schizophrenia" (NEWMEDS) in 2009, PET radioligands sensitive to an endogenous neurotransmitter were only validated for dopamine. NEWMEDS work-package 5, "Cross-species and neurochemical imaging (PET) methods for drug discovery", commenced with a focus on developing methods enabling assessment of changes in extracellular concentrations of serotonin and noradrenaline in the brain. RESULTS Sharing the workload across institutions, we utilized in vitro techniques with cells and tissues, in vivo receptor binding and microdialysis techniques in rodents, and in vivo PET imaging in non-human primates and humans. Here, we discuss these efforts and review other recently published reports on the use of radioligands to assess changes in endogenous levels of dopamine, serotonin, noradrenaline, γ-aminobutyric acid, glutamate, acetylcholine, and opioid peptides. The emphasis is on assessment of the availability of appropriate translational tools (PET radioligands, pharmacological challenge agents) and on studies in non-human primates and human subjects, as well as current challenges and future directions. CONCLUSIONS PET imaging directed at investigating changes in endogenous neurochemicals, including the work done in NEWMEDS, have highlighted an opportunity to further extend the capability and application of this technology in drug development.
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Affiliation(s)
- Sjoerd J. Finnema
- />Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Mika Scheinin
- />Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Turku, Finland , />Unit of Clinical Pharmacology, Turku University Hospital, Turku, Finland
| | - Mohammed Shahid
- />Research and Development, Orion Corporation, Orion Pharma, Turku, Finland
| | - Jussi Lehto
- />Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Turku, Finland
| | - Edilio Borroni
- />Neuroscience Department, Hoffman-La Roche, Basel, Switzerland
| | | | - Jukka Sallinen
- />Research and Development, Orion Corporation, Orion Pharma, Turku, Finland
| | - Erik Wong
- />Neuroscience Innovative Medicine Unit, AstraZeneca, Wilmington, DE USA
| | - Lars Farde
- />Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden , />Translational Science Center at Karolinska Institutet, AstraZeneca, Stockholm, Sweden
| | - Christer Halldin
- />Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Sarah Grimwood
- Neuroscience Research Unit, Pfizer Inc, Cambridge, MA, USA. .,, 610 Main Street, Cambridge, MA, 02139, USA.
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Licata SC, Jensen JE, Conn NA, Winer JP, Lukas SE. Zolpidem increases GABA in depressed volunteers maintained on SSRIs. Psychiatry Res 2014; 224:28-33. [PMID: 25082715 DOI: 10.1016/j.pscychresns.2014.05.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 05/03/2014] [Accepted: 05/16/2014] [Indexed: 12/25/2022]
Abstract
Individuals with major depressive disorder (MDD) often use hypnotics like zolpidem (Ambien(®)) to improve sleep in addition to their selective serotonin reuptake inhibitor (SSRI) regimen. SSRIs act in part to restore disrupted GABAergic activity, but benzodiazepines and related drugs have been shown to lower GABA in a way that may be counter to these therapeutic effects. The present within-subject, single-blind, placebo-controlled study measured changes in GABA in the anterior cingulate (ACC) and thalamus of volunteers maintained on SSRIs for the treatment of MDD (n=14) following zolpidem (10mg) administration. In addition to neurochemical measurements obtained using proton magnetic resonance spectroscopy ((1)H MRS) at 4 T, a series of questionnaires were administered to assess subjective effects associated with acute zolpidem exposure. Zolpidem elevated GABA levels in both voxels of interest (P<0.05) in the depressed participants, which could imply normalization, given the lower baseline levels associated with depression. The subjective drug experience in the depressed cohort was similar to that reported previously by healthy volunteers, and no relationships existed between GABA increases and the observed behavioral effects. Aside from treating insomnia, using zolpidem in the presence of SSRIs may have some unidentified therapeutic effects for depressed individuals.
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Affiliation(s)
- Stephanie C Licata
- Behavioral Psychopharmacology Research Laboratory, McLean Hospital/Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA
| | - J Eric Jensen
- McLean Imaging Center, McLean Hospital/Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA
| | - Nina A Conn
- Behavioral Psychopharmacology Research Laboratory, McLean Hospital/Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA
| | - Jeffrey P Winer
- Behavioral Psychopharmacology Research Laboratory, McLean Hospital/Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA
| | - Scott E Lukas
- Behavioral Psychopharmacology Research Laboratory, McLean Hospital/Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA; McLean Imaging Center, McLean Hospital/Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA.
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Kitaichi Y, Inoue T, Nakagawa S, Omiya Y, Song N, An Y, Chen C, Kusumi I, Koyama T. Local infusion of citalopram into the basolateral amygdala decreased conditioned fear of rats through increasing extracellular serotonin levels. Prog Neuropsychopharmacol Biol Psychiatry 2014; 54:216-22. [PMID: 24928686 DOI: 10.1016/j.pnpbp.2014.05.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 05/16/2014] [Accepted: 05/29/2014] [Indexed: 11/29/2022]
Abstract
Selective serotonin reuptake inhibitors (SSRIs) are widely used for the treatment of depressive disorders and anxiety disorders. The anxiolytic mechanism of SSRIs is currently unclear. To investigate the anxiolytic effects of SSRIs, we measured both freezing behavior and extracellular serotonin and dopamine levels in the basolateral amygdala when rats were given conditioned fear stress under local reverse-dialysis of citalopram, an SSRI, into the basolateral amygdala. Local administration of citalopram into the basolateral amygdala significantly decreased freezing behavior induced by conditioned fear stress, and serotonin levels were simultaneously found to be significantly higher. Furthermore, repeated conditioned fear stress under local infusion of citalopram into the basolateral amygdala induced further increases in extracellular dopamine levels. Further studies investigating the role of dopamine in the amygdala for conditioned fear stress will be necessary. These results suggest that the basolateral amygdala is one of the target areas of the anxiolytic effects of citalopram and the increases of extracellular serotonin levels in the basolateral amygdala may be related to the anxiolytic effects.
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Affiliation(s)
- Yuji Kitaichi
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo 060-8638, Japan.
| | - Takeshi Inoue
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo 060-8638, Japan
| | - Shin Nakagawa
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo 060-8638, Japan
| | - Yuki Omiya
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo 060-8638, Japan
| | - Ning Song
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo 060-8638, Japan
| | - Yan An
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo 060-8638, Japan
| | - Chong Chen
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo 060-8638, Japan
| | - Ichiro Kusumi
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo 060-8638, Japan
| | - Tsukasa Koyama
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo 060-8638, Japan
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Ten Eyck GR, Regen EM. Chronic fluoxetine treatment promotes submissive behavior in the territorial frog, Eleutherodactylus coqui. Pharmacol Biochem Behav 2014; 124:86-91. [DOI: 10.1016/j.pbb.2014.05.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 05/15/2014] [Accepted: 05/22/2014] [Indexed: 11/28/2022]
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Lasting neurobehavioral abnormalities in rats after neonatal activation of serotonin 1A and 1B receptors: possible mechanisms for serotonin dysfunction in autistic spectrum disorders. Psychopharmacology (Berl) 2014; 231:1191-200. [PMID: 23975037 PMCID: PMC3933458 DOI: 10.1007/s00213-013-3242-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 08/06/2013] [Indexed: 10/26/2022]
Abstract
RATIONALE Perinatal exposure of rats to selective serotonin reuptake inhibitors (SSRIs) produces sensory and social abnormalities paralleling those seen in autistic spectrum disorders (ASDs). However, the possible mechanism(s) by which this exposure produces behavioral abnormalities is unclear. OBJECTIVE We hypothesized that the lasting effects of neonatal SSRI exposure are a consequence of abnormal stimulation of 5-HT1A and/or 5-HT1B receptors during brain development. We examined whether such stimulation would result in lasting sensory and social deficits in rats in a manner similar to SSRIs using both direct agonist stimulation of receptors as well as selective antagonism of these receptors during SSRI exposure. METHODS Male and female rat pups were treated from postnatal days 8 to 21. In Experiment 1, pups received citalopram (20 mg/kg/day), saline, (±)-8-hydroxy-dipropylaminotetralin hydrobromide (8-OH-DPAT; 0.5 mg/kg/day) or 7-trifluoromethyl-4(4-methyl-1-piperazinyl)-pyrrolo[1,2-a]-quinoxaline dimaleate (CGS-12066B; 10 mg/kg/day). In Experiment 2, a separate cohort of pups received citalopram (20 mg/kg/day), or saline which was combined with either N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclo-hexanecarboxamide maleate (WAY-100635; 0.6 mg/kg/day) or N-[4-methoxy-3-(4-methyl-1-piperazinyl)phenyl]-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)-1-1'-biphenyl-4-carboxamide (GR-127935; 6 mg/kg/day) or vehicle. Rats were then tested in paradigms designed to assess sensory and social response behaviors at different time points during development. RESULTS Direct and indirect neonatal stimulation of 5-HT1A or 5-HT1B receptors disrupts sensory processing, produces neophobia, increases stereotypic activity, and impairs social interactions in manner analogous to that observed in ASD. CONCLUSION Increased stimulation of 5-HT1A and 5-HT1B receptors plays a significant role in the production of lasting social and sensory deficits in adult animals exposed as neonates to SSRIs.
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Ruhé HG, Koster M, Booij J, van Herk M, Veltman DJ, Schene AH. Occupancy of serotonin transporters in the amygdala by paroxetine in association with attenuation of left amygdala activation by negative faces in major depressive disorder. Psychiatry Res 2014; 221:155-61. [PMID: 24406081 DOI: 10.1016/j.pscychresns.2013.12.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 11/25/2013] [Accepted: 12/12/2013] [Indexed: 11/27/2022]
Abstract
Amygdala hyperactivation in major depressive disorder (MDD) might be attenuated by selective serotonin reuptake inhibitors (SSRIs), but the working mechanism remains unclear. We hypothesized that higher amygdala serotonin transporter (SERT) occupancy by paroxetine results in greater attenuation of amygdala activation by negative facial expressions in MDD patients. We treated fifteen MDD patients (22-55 years) with paroxetine 20-50mg/day. After 6 and 12 weeks, we quantified (1) clinical response (≥50% decrease in Hamilton Depression Rating Scale (HDRS), (2) SERT occupancy in both amygdala measured by repeated [123I]β-CIT single photon emission computed tomography (SPECT), and (3) amygdala activation when viewing fearful and angry (negative) faces with repeated functional MRI scans. Response rates were 4/15 and 9/15 at 6 and 12 weeks, respectively. Attenuation of left amygdala activation was associated with amygdala SERT occupancy (P=0.006) and response (P=0.015). This association may provide a rationale for decreased limbic activity seen during treatment of MDD. It might also explain the rapid decrease in negative attentional bias and amygdala activation caused by SSRIs.
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Affiliation(s)
- Henricus G Ruhé
- Program for Mood Disorders, Department of Psychiatry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; University of Groningen, University Medical Center Groningen, Mood and Anxiety Disorders, Department of Psychiatry, Groningen, The Netherlands.
| | - Michiel Koster
- Program for Mood Disorders, Department of Psychiatry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Jan Booij
- Department of Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Marcel van Herk
- Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands
| | - Dick J Veltman
- Department of Psychiatry VUMC, Vrije Universiteit, Amsterdam, The Netherlands
| | - Aart H Schene
- Program for Mood Disorders, Department of Psychiatry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Department of Psychiatry, Radboud University Medical Center, Nijmegen, The Netherlands; Donders Institute for Brain, Cognition and Behavior, Radboud University, Nijmegen, The Netherlands
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Effect of a single dose of escitalopram on serotonin concentration in the non-human and human primate brain. Int J Neuropsychopharmacol 2013; 16:1577-86. [PMID: 23351590 DOI: 10.1017/s1461145712001617] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Selective serotonin reuptake inhibitors (SSRIs) are widely prescribed for treatment of psychiatric disorders. The exact mechanism underlying the clinical effects of SSRIs remains unclear, although increased synaptic serotonin concentrations have been hypothesized to be an initial step. [¹¹C]AZ10419369 is a novel 5-HT(1B) receptor selective radioligand, which is sensitive to changes in endogenous serotonin concentrations. To assess whether a single dose of the SSRI escitalopram affects endogenous serotonin concentrations in serotonergic projection areas and in the raphe nuclei (RN), three cynomolgus monkeys and nine human subjects underwent PET examinations with [¹¹C]AZ10419369 at baseline conditions and after escitalopram administration. In monkeys, the binding potential (BP(ND)) was significantly lower post dose compared to baseline in dorsolateral prefrontal cortex, occipital cortex, thalamus, midbrain and RN (p < 0.05). In humans, the BP(ND) tended to decrease in RN post dose (p = 0.08). In all serotonergic projection areas, the BP(ND) was conversely higher post dose compared to baseline. The increase was significant in a combined region of all projection areas (p = 0.01) and in occipital and temporal cortex (p < 0.05). SSRIs are generally assumed to elevate endogenous serotonin concentrations in projection areas, evoking the antidepressant effect. In the present study, a single, clinically relevant, dose of escitalopram was found to decrease serotonin concentrations in serotonergic projection areas in humans. Hypothetically, desensitization of inhibitory serotonergic autoreceptors will cause the serotonin concentration in projection areas to increase over time with chronic administration. Thus, the findings in the present study might aid in understanding the mechanism of SSRIs' delayed onset of clinical effect.
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Masuda T, Nishikawa H, Inoue T, Toda H, Nakagawa S, Boku S, Koyama T. 5-HT depletion, but not 5-HT1A antagonist, prevents the anxiolytic-like effect of citalopram in rat contextual conditioned fear stress model. Acta Neuropsychiatr 2013; 25:77-84. [PMID: 25287308 DOI: 10.1111/j.1601-5215.2012.00669.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Selective serotonin reuptake inhibitors (SSRIs) have been widely used in the treatment of most anxiety disorders. In this study, to clarify the mechanism of the anxiolytic effect, we investigated the mechanism underlying the effect of the SSRI citalopram on rat contextual conditioned fear stress (CFS), an animal model of anxiety. METHODS Rats individually received footshocks in a shock chamber. More than 1 day later, they were given citalopram and/or dl-p-chlorophenylalanine (PCPA), various subtype-selective serotonin (5-HT) receptor antagonists: the 5-HT1A receptor antagonist WAY 100635, the 5-HT2A receptor antagonist MDL 100907, the 5-HT2C receptor antagonist SB 242084, the 5-HT3 receptor antagonist tropisetron, the 5-HT4 receptor antagonist GR 125487, the 5-HT6 receptor antagonist SB 258585 or the 5-HT7 receptor antagonist SB 269970. After drug administration, freezing behaviour, which was used as an index of anxiety, was analysed in the same shock chamber without shocks. RESULTS Citalopram dose dependently reduced conditioned freezing behaviour. The anxiolytic-like effect of citalopram was prevented completely by pretreatment with the 5-HT-depleting agent PCPA, but not by the 5-HT1A receptor antagonist WAY 100635. Furthermore, none of the subtype-selective 5-HT receptor antagonists significantly affected conditioned freezing or affected the anxiolytic-like effect of citalopram. CONCLUSION The anxiolytic-like effect of citalopram in contextual CFS model depends on 5-HT availability. In addition, contextual CFS model is suggested to be completely different from conventional anxiety models in neural mechanism or manners of serotonergic involvement. However, further studies are needed to identify the pharmacological mechanisms responsible for the anxiolytic-like effect of citalopram.
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Affiliation(s)
- Takahiro Masuda
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, Japan
| | - Hiroyuki Nishikawa
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, Japan
| | - Takeshi Inoue
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, Japan
| | - Hiroyuki Toda
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, Japan
| | - Shin Nakagawa
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, Japan
| | - Shuken Boku
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, Japan
| | - Tsukasa Koyama
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, Japan
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Descarries L, Riad M. Effects of the antidepressant fluoxetine on the subcellular localization of 5-HT1A receptors and SERT. Philos Trans R Soc Lond B Biol Sci 2012; 367:2416-25. [PMID: 22826342 DOI: 10.1098/rstb.2011.0361] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Serotonin (5-HT) 5-HT(1A) autoreceptors (5-HT(1A)autoR) and the plasmalemmal 5-HT transporter (SERT) are key elements in the regulation of central 5-HT function and its responsiveness to antidepressant drugs. Previous immuno-electron microscopic studies in rats have demonstrated an internalization of 5-HT(1A)autoR upon acute administration of the selective agonist 8-OH-DPAT or the selective serotonin reuptake inhibitor antidepressant fluoxetine. Interestingly, it was subsequently shown in cats as well as in humans that this internalization is detectable by positron emission tomography (PET) imaging with the 5-HT(1A) radioligand [(18)F]MPPF. Further immunocytochemical studies also revealed that, after chronic fluoxetine treatment, the 5-HT(1A)autoR, although present in normal density on the plasma membrane of 5-HT cell bodies and dendrites, do not internalize when challenged with 8-OH-DPAT. Resensitization requires several weeks after discontinuation of the chronic fluoxetine treatment. In contrast, the SERT internalizes in both the cell bodies and axon terminals of 5-HT neurons after chronic but not acute fluoxetine treatment. Moreover, the total amount of SERT immunoreactivity is then reduced, suggesting that SERT is not only internalized, but also degraded in the course of the treatment. Ongoing and future investigations prompted by these finding are briefly outlined by way of conclusion.
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Affiliation(s)
- Laurent Descarries
- Departments of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, , Montreal, Quebec, Canada H3C 3J7.
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Measuring endogenous changes in serotonergic neurotransmission in humans: a [11C]CUMI-101 PET challenge study. Mol Psychiatry 2012; 17:1254-60. [PMID: 22665264 DOI: 10.1038/mp.2012.78] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Serotonin (5-HT) neurotransmission is implicated in cognitive and emotional processes and a number of neuropsychiatric disorders. The use of positron emission tomography (PET) to measure ligand displacement has allowed estimation of endogenous dopamine release in the human brain; however, applying this methodology to assess central 5-HT release has proved more challenging. The aim of this study was to assess the sensitivity of a highly selective 5-HT(1A) partial agonist radioligand [(11)C]CUMI-101 to changes in endogenous 5-HT levels induced by an intravenous challenge with the selective 5-HT re-uptake inhibitor (SSRI), citalopram, in healthy human participants. We studied 15 healthy participants who underwent PET scanning in conjunction with [(11)C]CUMI-101 after receiving an intravenous infusion of citalopram 10 mg or placebo in a double-blind, crossover, randomized design. Regional estimates of binding potential (BP(ND)) were obtained by calculating total volumes of distribution (V(T)) for presynaptic dorsal raphe nucleus (DRN) and postsynaptic cortical regions. Relative to placebo, citalopram infusion significantly increased [(11)C]CUMI-101 BP(ND) at postsynaptic 5-HT(1A) receptors in several cortical regions, but there was no change in binding at 5-HT(1A) autoreceptors in the DRN. Across the postsynaptic brain regions, citalopram treatment induced a mean 7% in [(11)C]CUMI-101 BP(ND) (placebo 1.3 (0.2); citalopram 1.4 (0.2); paired t-test P=0.003). The observed increase in postsynaptic [(11)C]CUMI-101 availability identified following acute citalopram administration could be attributable to a decrease in endogenous 5-HT availability in cortical terminal regions, consistent with preclinical animal studies, in which acute administration of SSRIs decreases DRN cell firing through activation of 5-HT(1A) autoreceptors to reduce 5-HT levels in postsynaptic regions. We conclude that [(11)C]CUMI-101 may be sensitive to changes in endogenous 5-HT release in humans.
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Takamura N, Masuda T, Inoue T, Nakagawa S, Koyama T. The effects of the co-administration of the α₁-adrenoreceptor antagonist prazosin on the anxiolytic effect of citalopram in conditioned fear stress in the rat. Prog Neuropsychopharmacol Biol Psychiatry 2012; 39:107-11. [PMID: 22658980 DOI: 10.1016/j.pnpbp.2012.05.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 05/10/2012] [Accepted: 05/23/2012] [Indexed: 10/28/2022]
Abstract
Several studies have shown that the α₁-adrenoreceptor is involved in controlling extracellular serotonin levels. The administration of the α₁-adrenoreceptor antagonist prazosin was shown to decrease extracellular serotonin levels in the hippocampus, the prefrontal cortex and the raphe nucleus, while the administration of the α₁-adrenoreceptor agonist cirazoline was shown to increase serotonin levels. Furthermore, the elevation of serotonin levels induced by the selective serotonin reuptake inhibitor (SSRI) citalopram was attenuated by prazosin. Thus, α₁-adrenoreceptor antagonists may affect SSRI-induced increases in extracellular serotonin levels and their antidepressive and anxiolytic effects. However, little is known about the influence of α₁-adrenoreceptor antagonists on the behavioral pharmacological effects of SSRIs. The conditioned fear stress-induced freezing behavior is an animal model of anxiety and can detect the anxiolytic effect of SSRIs. To clarify whether an α₁-adrenoreceptor antagonist affects the anxiolytic action of SSRIs, we examined the effects of the co-administration of the α₁-adrenoreceptor antagonist prazosin and the SSRI citalopram using the contextual conditioned fear stress model. Low-dose prazosin (0.03 mg/kg) significantly attenuated the citalopram (3 mg/kg)-induced decrease in conditioned freezing. Moreover, high-dose (0.5 mg/kg), but not low-dose (0.03 mg/kg), prazosin significantly attenuated citalopram (10 mg/kg)-induced decreases in conditioned freezing. These drugs did not affect the spontaneous motor activity of the rats. Therefore, these results suggest that blocking the α₁-adrenoreceptor decreases the anxiolytic effect of citalopram.
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Affiliation(s)
- Naoki Takamura
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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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.
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Hueletl‐Soto ME, Carro‐Juárez M, Rodríguez‐Manzo G. Fluoxetine Chronic Treatment Inhibits Male Rat Sexual Behavior by Affecting Both Copulatory Behavior and the Genital Motor Pattern of Ejaculation. J Sex Med 2012; 9:1015-26. [DOI: 10.1111/j.1743-6109.2011.02339.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Sturzu A, Sheikh S, Klose U, Echner H, Kalbacher H, Deeg M, Nägele T, Horger M, Ernemann U, Heckl S. Using the neurotransmitter serotonin to target imaging agents to glioblastoma cells. Invest New Drugs 2012; 30:2141-7. [DOI: 10.1007/s10637-011-9781-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Masuda T, Nakagawa S, Boku S, Nishikawa H, Takamura N, Kato A, Inoue T, Koyama T. Noradrenaline increases neural precursor cells derived from adult rat dentate gyrus through β2 receptor. Prog Neuropsychopharmacol Biol Psychiatry 2012; 36:44-51. [PMID: 21914456 DOI: 10.1016/j.pnpbp.2011.08.019] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Revised: 08/18/2011] [Accepted: 08/23/2011] [Indexed: 11/30/2022]
Abstract
Several preclinical researches indicate that increased neurogenesis in the adult hippocampus might underlie the therapeutic effect of antidepressant treatment. Most antidepressant drugs have ability to increase serotonin (5-HT) and/or noradrenaline (NA) in brain, and chronic treatment with antidepressant drugs increases the number of proliferating neural precursor cells and neurogenesis in hippocampus. However, the direct effects of antidepressant drugs, 5-HT and NA on the neural precursor cells remain largely unknown. Neural precursor cells in adult hippocampus are divided into stem/progenitor cells of four types based on stages of neural development. We recently established a culture system of adult rat dentate gyrus-derived neural precursor cells (ADPs), which correspond to be type 2a early progenitor cells. Here the direct effects of antidepressant drugs of four types (fluoxetine, imipramine, reboxetine, and tranylcypromine) and two neurotransmitters (5-HT and NA) on the proliferation of ADPs were investigated. Neither antidepressant drugs of all types nor 5-HT increased the number of ADPs. On the other hand, NA increased the number and the DNA synthesis of ADPs. The effect of NA on ADP proliferation was antagonized by propranolol and timolol (β-adrenergic receptor (AR) antagonists), but not by phentolamine (α-AR antagonist), prazosin (α1-AR antagonist), or yohimbine (α2-AR antagonist). Moreover, it was antagonized by ICI 118, 551 (β2-AR selective antagonist) and salmeterol (β2-AR selective agonist) promoted ADP proliferation. These results suggest that NA might increase the proliferation of early progenitor cells in adult hippocampus via β2-AR directly, but antidepressant drugs and 5-HT do not.
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Affiliation(s)
- Takahiro Masuda
- Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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Zhu CB, Lindler KM, Campbell NG, Sutcliffe JS, Hewlett WA, Blakely RD. Colocalization and regulated physical association of presynaptic serotonin transporters with A₃ adenosine receptors. Mol Pharmacol 2011; 80:458-65. [PMID: 21705486 DOI: 10.1124/mol.111.071399] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of A₃ adenosine receptors (A₃ARs) rapidly enhances the activity of antidepressant-sensitive serotonin (5-HT) transporters (SERTs) in vitro, ex vivo, and in vivo. A₃AR agonist stimulation of SERT activity is lost in A₃AR knockout mice. A₃AR-stimulated SERT activity is mediated by protein kinase G1 (PKGI)- and p38 mitogen-activated protein kinase (MAPK)-linked pathways that support, respectively, enhanced SERT surface expression and catalytic activation. The mechanisms by which A₃ARs target SERTs among other potential effectors is unknown. Here we present evidence that A₃ARs are coexpressed with SERT in midbrain serotonergic neurons and form a physical complex in A₃AR/hSERT cotransfected cells. Treatment of A₃AR/SERT-cotransfected Chinese hamster ovary cells with the A₃AR agonist N⁶-(3-iodobenzyl)-N-methyl-5'-carbamoyladenosine (1 μM, 10 min), conditions previously reported to increase SERT surface expression and 5-HT uptake activity, enhanced the abundance of A₃AR/SERT complexes in a PKGI-dependent manner. Cotransfection of SERT with L90V-A₃AR, a hyperfunctional coding variant identified in subjects with autism spectrum disorder, resulted in a prolonged recovery of receptor/transporter complexes after A₃AR activation. Because PKGI and nitric-oxide synthetase are required for A₃AR stimulation of SERT activity, and proteins PKGI and NOS both form complexes with SERT, our findings suggest a mechanism by which signaling pathways coordinating A₃AR signaling to SERT can be spatially restricted and regulated, as well as compromised by neuropsychiatric disorders.
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Affiliation(s)
- Chong-Bin Zhu
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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Nagayasu K, Yatani Y, Kitaichi M, Kitagawa Y, Shirakawa H, Nakagawa T, Kaneko S. Utility of organotypic raphe slice cultures to investigate the effects of sustained exposure to selective 5-HT reuptake inhibitors on 5-HT release. Br J Pharmacol 2011; 161:1527-41. [PMID: 20698856 DOI: 10.1111/j.1476-5381.2010.00978.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND AND PURPOSE Selective 5-hydroxytryptamine (5-HT, serotonin) reuptake inhibitors (SSRIs) are widely used antidepressants and their therapeutic effect requires several weeks of drug administration. The delayed onset of SSRI efficacy is due to the slow neuroadaptive changes of the 5-hydroxytryptaminergic (5-HTergic) system. In this study, we examined the acute and chronic effects of SSRIs on the 5-HTergic system using rat raphe slice cultures. EXPERIMENTAL APPROACH For organotypic raphe slice cultures, mesencephalic coronal sections containing dorsal and median raphe nuclei were prepared from neonatal Wistar rats and cultured for 14-16 days. KEY RESULTS Acute treatment with citalopram, paroxetine or fluoxetine (0.1-10 µM) in the slice cultures slightly increased extracellular 5-HT levels, while sustained exposure for 4 days augmented the elevation of 5-HT level in a time-dependent manner. Sustained exposure to citalopram had no effect on tissue contents of 5-HT and its metabolite, expression of tryptophan hydroxylase or the membrane expression of 5-HT transporters. The augmented 5-HT release was attenuated by Ca(2+) -free incubation medium or treatment with tetrodotoxin. Experiments with 5-HT(1A/B) receptor agonists and antagonists revealed that desensitization of 5-HT(1) autoreceptors was not involved in the augmentation of 5-HT release. Finally, co-treatment with an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate, but not an N-methyl-d-aspartate, receptor antagonist, suppressed this augmentation. CONCLUSION AND IMPLICATIONS These results suggest that sustained exposure to SSRIs induces the augmentation of exocytotic 5-HT release, which is caused, at least in part, by the activation of AMPA/kainate receptors in the raphe slice cultures.
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Affiliation(s)
- Kazuki Nagayasu
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, Japan
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Xin ZC, Zhu YC, Yuan YM, Cui WS, Jin Z, Li WR, Liu T. Current therapeutic strategies for premature ejaculation and future perspectives. Asian J Androl 2011; 13:550-7. [PMID: 21532601 DOI: 10.1038/aja.2010.130] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Premature ejaculation (PE) is a common sexual disorder in men that is mediated by disturbances in the peripheral and central nervous systems. Although all pharmaceutical treatments for PE are currently used 'off-label', some novel oral agents and some newer methods of drug administration now provide important relief to PE patients. However, the aetiology of this condition has still not been unified, primarily because of the lack of a standard animal model for basic research and the absence of a widely accepted definition and assessment tool for evidence-based clinical studies in patients with PE. In this review, we focus on the current therapeutic strategies and future treatment perspectives for PE.
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Affiliation(s)
- Zhong-Cheng Xin
- Andrology Centre of Peking University First Hospital, Peking University, Beijing 100034, China.
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The double edged sword of neural plasticity: increasing serotonin levels leads to both greater vulnerability to depression and improved capacity to recover. Psychoneuroendocrinology 2011; 36:339-51. [PMID: 20875703 DOI: 10.1016/j.psyneuen.2010.08.011] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 08/27/2010] [Accepted: 08/29/2010] [Indexed: 12/21/2022]
Abstract
Major depression is a chronic, recurring and potentially life-threatening illness that affects up to 10% of the population worldwide. Pharmacological and genetic studies highlight the serotonergic system as being a key player in the disorder. However, despite drugs designed to boost serotonin transmission represent the first line of therapy for depression, the role of this system still remains elusive. Here, I propose a new theoretical framework, the undirected susceptibility to change model, potentially accounting for the experimental and clinical results concerning the role of this neurotransmitter in depression. Since the capacity of the individual to change its physiology and behavior according to the environment is dependent on neural plasticity which, in turn, is controlled by serotonin, I assume that changes in the levels of serotonin affect the sensitivity to the environment. Consequently, the undirected susceptibility to change model predicts that an increase of serotonin levels, for instance induced through selective serotonin reuptake inhibitor (SSRI) administration, does not affect mood per se, but--acting as a catalyzer--enhances neural plasticity and, thus, the effects of the environment on mood. However, since the environment can be either supportive or adverse, its effects can be beneficial or detrimental. Therefore enhancing the serotonin system can increase the likelihood both of developing the psychopathology and recovering from it. This model, on the one hand, suggests an explanation for the limited SSRI efficacy described in clinical studies and allows apparently contradictory data to be reconciled; on the other, it describes neural plasticity as a double edged sword that, according to the quality of the environment, may have either positive or negative consequences.
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Krishnamoorthy S, Ma Z, Zhang G, Wei J, Auerbach SB, Tao R. Involvement of 5-HT2A receptors in the serotonin (5-HT) syndrome caused by excessive 5-HT efflux in rat brain. Basic Clin Pharmacol Toxicol 2011; 107:830-41. [PMID: 20456331 DOI: 10.1111/j.1742-7843.2010.00586.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Previous studies have demonstrated that serotonin (5-HT) syndromes, particularly for the malignant cases, can be alleviated by ice water mists, cooling blankets and many other external cooling measures. In this study, we tested the hypothesis that external cooling measures reduce the responsivity of 5-HT(2A) receptors to excessive 5-HT efflux, which may be a possible mechanism underlying the treatment of serotonin syndrome. To test this, rat experiments were carried out in the standard and cool ambient temperature (T(amb) ) by administration of the 5-HT precursor 5-hydroxy-L-tryptophan combined with the monoamine oxidase inhibitor clorgyline. The first set of experiments was to assess severity of the syndromes by measuring body temperature responses. Consistent with the hypothesis, we found that the syndrome was malignant at the standard T(amb) of 22°C but alleviated at 12 or 6°C, these results being similar to those in rats pre-treated with the 5-HT(2A) receptor antagonist ketanserin. The second set of experiments was to utilize microdialysis to determine the relationship between the syndrome severity and 5-HT levels at the above-mentioned T(amb) . We found that excessive 5-HT efflux consisted of primary and secondary components through two distinct mechanisms. Furthermore, the secondary component efflux, which can be ascribed to 5-HT(2A) receptor activation, was proportionally reduced at the cool T(amb) of 12 and 6°C. In conclusion, results of this study support the hypothesis that cooling T(amb) reduces the functional activity of 5-HT(2A) receptors, thus alleviating the malignant syndrome.
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Affiliation(s)
- Swapna Krishnamoorthy
- Charles E. Schmidt College of Biomedical Science, Florida Atlantic University, Boca Raton, FL, USA
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Burnett AL, Goldstein I, Andersson KE, Argiolas A, Christ G, Park K, Xin ZC. Future sexual medicine physiological treatment targets. J Sex Med 2011; 7:3269-304. [PMID: 21029380 DOI: 10.1111/j.1743-6109.2010.02025.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
INTRODUCTION Sexual function in men and women incorporates physiologic processes and regulation of the central and peripheral nervous systems, the vascular system, and the endocrine system. There is need for state-of-the-art information as there is an evolving research understanding of the underlying molecular biological factors and mechanisms governing sexual physiologic functions. AIM To develop an evidence-based, state-of-the-art consensus report on the current knowledge of the major cellular and molecular targets of biologic systems responsible for sexual physiologic function. METHODS State-of-the-art knowledge representing the opinions of seven experts from four countries was developed in a consensus process over a 2-year period. MAIN OUTCOME MEASURES Expert opinion was based on the grading of evidence-based medical literature, widespread internal committee discussion, public presentation, and debate. RESULTS Scientific investigation in this field is needed to increase knowledge and foster development of the future line of treatments for all forms of biological-based sexual dysfunction. This article addresses the current knowledge of the major cellular and molecular targets of biological systems responsible for sexual physiologic function. Future treatment targets include growth factor therapy, gene therapy, stem and cell-based therapies, and regenerative medicine. CONCLUSIONS Scientific discovery is critically important for developing new and increasingly effective treatments in sexual medicine. Broad physiologic directions should be vigorously explored and considered for future management of sexual disorders.
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Affiliation(s)
- Arthur L Burnett
- The James Buchanan Brady Urological Institute, The Johns Hopkins Hospital, Baltimore, MD, USA.
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Miguel TLB, Pobbe RLH, Spiacci A, Zangrossi H. Dorsal raphe nucleus regulation of a panic-like defensive behavior evoked by chemical stimulation of the rat dorsal periaqueductal gray matter. Behav Brain Res 2010; 213:195-200. [DOI: 10.1016/j.bbr.2010.04.055] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 04/26/2010] [Accepted: 04/29/2010] [Indexed: 11/24/2022]
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Central and peripheral anti-inflammatory effects of maprotiline on carrageenan-induced paw edema in rats. Inflamm Res 2010; 59:1053-9. [PMID: 20574769 DOI: 10.1007/s00011-010-0225-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 06/02/2010] [Accepted: 06/02/2010] [Indexed: 10/19/2022] Open
Abstract
OBJECTIVE To explore the site of action of maprotiline, as an atypical antidepressant, on carrageenan-induced paw edema. SUBJECTS Male Wistar rats were used. METHODS Firstly, the anti-inflammatory effect of systemic maprotiline (12.5, 25 and 50 mg kg(-1)) was assessed using a paw edema model. Secondly, different doses of maprotiline were administrated intracerebroventricularly, intrathecally and locally before carrageenan challenge. Finally, we tried to reverse the anti-inflammatory effect of maprotiline by propranolol (10 mg kg(-1)), prazosin (4 mg kg(-1)), yohimbine (10 mg kg(-1)), naloxone (4 mg kg(-1)) and mifepristone (5 mg kg(-1)). RESULTS Systemic, intracerebroventricular and subplantar application of maprotiline significantly inhibited peripheral edema, but intrathecal maprotiline did not alter the degree of paw swelling. The applied antagonists failed to change the anti-inflammatory activity of maprotiline. CONCLUSION These results demonstrate that maprotiline has a potent anti-inflammatory effect and this effect is linked to the peripheral and supraspinal actions of the drug.
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Differential effects of acute and repeated citalopram in mouse models of anxiety and depression. Int J Neuropsychopharmacol 2010; 13:321-34. [PMID: 20003619 PMCID: PMC3646514 DOI: 10.1017/s1461145709990630] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Clinically, SSRIs are widely prescribed in the treatment of several anxiety disorders, although very few pre-clinical studies have observed a beneficial effect of this class of drugs in animal models of anxiety. Furthermore, the biphasic pattern observed clinically, an exacerbation of anxiety followed by beneficial effects, is rarely observed in animal studies. In the present study we document this clinical phenomenon in several behavioural paradigms. While a single injection of citalopram induced anxiogenic effects, three administrations of citalopram were sufficient to elicit anxiolytic effects. Congruent with these data, we observed that short-term repeated administration of citalopram was accompanied by increased activation of cAMP response element-binding protein (CREB) in the hippocampus and desensitization of 5-HT1A receptors, two phenomena well associated with chronic rather than acute actions of antidepressants. Moreover, effects of citalopram were abolished in CREBalphaDelta mutant animals in the elevated zero maze (EZM) and tail suspension test (TST), but not in novelty-induced hypophagia (NIH). Further, the desensitization of 5-HT1A receptors elicited by citalopram was not affected by CREB deficiency. The significance of the EZM and TST paradigms in predicting therapeutic efficacy is well known while effects in NIH and 5-HT1A sensitization are less well-established. These data demonstrate that behavioural responses to citalopram are dependent on the frequency of its administration, and that these responses are differentially dependent on CREB function.
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Autoradiographic study of serotonin transporter during memory formation. Behav Brain Res 2010; 212:12-26. [PMID: 20226815 DOI: 10.1016/j.bbr.2010.03.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 03/05/2010] [Indexed: 12/15/2022]
Abstract
Serotonin transporter (SERT) has been associated with drugs of abuse like d-methamphetamine (METH). METH is well known to produce effects on the monoamine systems but it is unclear how METH affects SERT and memory. Here the effects of METH and the serotonin reuptake inhibitor fluoxetine (FLX) on autoshaping and novel object recognition (NOR) were investigated. Notably, both memory tasks recruit different behavioral, neural and cognitive demand. In autoshaping task a dose-response curve for METH was determined. METH (1.0mg/kg) impaired short-term memory (STM; lasting less of 90min) in NOR and impaired both STM and long-term memory (LTM; lasting 24 and 48h) in autoshaping, indicating that METH had long-lasting effects in the latter task. A comparative autoradiography study of the relationship between the binding pattern of SERT in autoshaping new untrained vs. trained treated (METH, FLX, or both) animals was made. Considering that hemispheric dominance is important for LTM, hence right vs. left hemisphere of the brain was compared. Results showed that trained animals decreased cortical SERT binding relative to untrained ones. In untrained and trained treated animals with the amnesic dose (1.0mg/kg) of METH SERT binding in several areas including hippocampus and cortex decreased, more remarkably in the trained animals. In contrast, FLX improved memory, increased SERT binding, prevented the METH amnesic effect and re-established the SERT binding. In general, memory and amnesia seemed to make SERT more vulnerable to drugs effects.
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Zhang G, Krishnamoorthy S, Ma Z, Vukovich NP, Huang X, Tao R. Assessment of 5-hydroxytryptamine efflux in rat brain during a mild, moderate and severe serotonin-toxicity syndrome. Eur J Pharmacol 2009; 615:66-75. [PMID: 19464285 PMCID: PMC2756783 DOI: 10.1016/j.ejphar.2009.05.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 05/01/2009] [Accepted: 05/14/2009] [Indexed: 11/30/2022]
Abstract
Serotonin (5-hydroxytryptamine; 5-HT)-toxicity syndrome, an iatrogenic brain disorder induced by excessive efflux of 5-HT, has received much attention because of increasing incidents of serotonergic antidepressants. However, the neural mechanism by which extracellular 5-HT is elevated to a toxic level for the syndrome remains to be determined. The goal of the present study was to test the hypothesis that extracellular 5-HT is composed of two component effluxes responsible for distinct aspects of the syndrome. The first set of experiments was to characterize the syndrome by measuring changes in neuromuscular signs, body-core temperature and mortality rate. Our results indicate that the syndrome severity can be categorized into mild, moderate and severe levels. The second set of experiments was to determine a threshold of extracellular 5-HT for induction of each level of the syndrome. Our results demonstrate that there were an 11-fold increase in the mild syndrome and an over 55-fold increase in the severe syndrome. In the last series of experiments, the excessive increases in 5-HT were pharmacologically separated into primary and secondary component effluxes with the 5-HT2A receptor antagonists cyproheptadine and ketanserin and NMDA receptor antagonist (+)-MK-801. Our results suggest that the primary component efflux was caused by direct drug effects on 5-HT biosynthetic and metabolic pathways and secondary efflux ascribed to indirect drug effect on a positive-feedback circuit involving 5-HT2A and NMDA receptors. In summary, the primary efflux could be an initial cause for the induction of the syndrome while the secondary efflux might involve deterioration of the syndrome.
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Affiliation(s)
- Gongliang Zhang
- Charles E. Schmidt College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida 33431, U.S.A
| | - Swapna Krishnamoorthy
- Charles E. Schmidt College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida 33431, U.S.A
| | - Zhiyuan Ma
- Charles E. Schmidt College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida 33431, U.S.A
| | - Nick P. Vukovich
- Charles E. Schmidt College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida 33431, U.S.A
| | - Xupei Huang
- Charles E. Schmidt College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida 33431, U.S.A
| | - Rui Tao
- Charles E. Schmidt College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida 33431, U.S.A
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Enhancement of cortical extracellular 5-HT by 5-HT1A and 5-HT2C receptor blockade restores the antidepressant-like effect of citalopram in non-responder mice. Int J Neuropsychopharmacol 2009; 12:793-803. [PMID: 19123962 DOI: 10.1017/s1461145708009760] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We recently found that the response of DBA/2 mice to SSRIs in the forced swim test (FST) was impaired and they also had a smaller basal and citalopram-stimulated increase in brain extracellular serotonin (5-HT) than 'responder' strains. We employed intracerebral microdialysis, FST and selective antagonists of 5-HT1A and 5-HT2C receptors to investigate whether enhancing the increase in extracellular 5-HT reinstated the anti-immobility effect of citalopram in the FST. WAY 100635 (0.3 mg/kg s.c.) or SB 242084 (1 mg/kg s.c.), respectively a selective 5-HT1A and 5-HT2C receptor antagonist, raised the effect of citalopram (5 mg/kg) on extracellular 5-HT in the medial prefrontal cortex of DBA/2N mice (citalopram alone 5.2+/-0.3 fmol/20 microl, WAY 100635+citalopram 9.9+/-2.1 fmol/20 microl, SB 242084+ citalopram 7.6+/-1.0 fmol/20 microl) to the level reached in 'responder' mice given citalopram alone. The 5-HT receptor antagonists had no effect on the citalopram-induced increase in extracellular 5-HT in the dorsal hippocampus. The combination of citalopram with WAY 100635 or SB 242084 significantly reduced immobility time in DBA/2N mice that otherwise did not respond to either drug singly. Brain levels of citalopram in mice given citalopram alone or with 5-HT antagonists did not significantly differ. The results confirm that impaired 5-HT transmission accounts for the lack of effect of citalopram in the FST and suggest that enhancing the effect of SSRIs on extracellular 5-HT, through selective blockade of 5-HT1A and 5-HT2C receptors, could be a useful strategy to restore the response in treatment-resistant depression.
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