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Pönicke K, Gergs U, Buchwalow IB, Hauptmann S, Neumann J. On the presence of serotonin in mammalian cardiomyocytes. Mol Cell Biochem 2012; 365:301-12. [PMID: 22367115 DOI: 10.1007/s11010-012-1270-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 02/16/2012] [Indexed: 10/28/2022]
Abstract
Pleiotropic effects of serotonin (5-HT) in the cardiovascular system are well documented. However, it remains to be elucidated, whether 5-HT is present in adult mammalian cardiomyocytes. To address this issue, we investigated the levels of 5-HT in blood, plasma, platelets, cardiac tissue, and cardiomyocytes from adult mice and for comparison in human right atrial tissue. Immunohistochemically, 5-HT was hardly found in mouse cardiac tissue, but small amounts could be detected in renal preparations, whereas adrenal preparations revealed a strong positive immunoreaction for 5-HT. Using a sensitive HPLC detection system, 5-HT was also detectable in the mouse heart and human atrium. Furthermore, we could identify 5-HT in isolated cardiomyocytes from adult mice. These findings were supported by detection of the activity of 5-HT-forming enzymes-tryptophan hydroxylase and aromatic L-amino acid decarboxylase-in isolated cardiomyocytes from adult mice and by inhibition of these enzymes with p-chlorophenylalanine and 3-hydroxybenzyl hydrazine. Addition of the first intermediate of 5-HT generation, that is 5-hydroxytryptophan, enhanced the 5-HT level and inhibition of monoamine oxidase by tranylcypromine further increased the level of 5-HT. Our findings reveal the presence and synthesis of 5-HT in cardiomyocytes of the mammalian heart implying that 5-HT may play an autocrine and/or paracrine role in the heart.
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Affiliation(s)
- Klaus Pönicke
- Medical Faculty, Institute of Pharmacology and Toxicology, Martin-Luther-University Halle-Wittenberg, Magdeburger Str. 4, 06112, Halle (Saale), Germany
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202
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Ziu E, Mercado CP, Li Y, Singh P, Ahmed BA, Freyaldenhoven S, Lensing S, Ware J, Kilic F. Down-regulation of the serotonin transporter in hyperreactive platelets counteracts the pro-thrombotic effect of serotonin. J Mol Cell Cardiol 2012; 52:1112-21. [PMID: 22366712 DOI: 10.1016/j.yjmcc.2012.02.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 02/01/2012] [Accepted: 02/07/2012] [Indexed: 01/08/2023]
Abstract
An elevated plasma concentration of serotonin ([5-HT]) is a common feature of cardiovascular disease often associated with enhanced platelet activation and thrombosis. Whether elevated in vivo plasma 5-HT per se represents an independent risk factor for platelet hyperreactivity or only is an epiphenomenon of cardiovascular disease is poorly understood. We examined in vitro and in vivo platelet function following a 24h elevation of plasma [5-HT] in mice. In vivo administration of 5-HT using osmotic minipumps increased plasma [5-HT] in treated mice compared to control mice instrumented with saline loaded pumps. 5-HT infusion did not increase systolic blood pressure, but markers of platelet activation including P-selectin and (PE)Jon/A staining were increased and these findings coincided with the enhanced aggregation of isolated platelets in response to type I fibrillar collagen. Tail bleeding times and the time to occlusion following chemical damage to the carotid artery were shortened in 5-HT-infused mice. 5-HT-infused mice were treated with paroxetine (Prx) to block 5-HT uptake via the serotonin transporter (SERT). Prx lowered platelet [5-HT] and attenuated platelet activation and aggregation. These results and our biochemical indices of enhanced 5-HT intracellular signaling in the platelets of 5-HT-infused mice reveal a mechanistic link between elevated plasma [5-HT], abnormal intracellular 5-HT signaling and accentuated platelet aggregation. Although a down-regulation of the serotonin transporter (SERT) on the platelet surface may counteract the pro-thrombotic influence of elevated plasma [5HT], this compensatory mechanism may fail to prevent the increased thrombotic risk caused by elevated plasma [5-HT].
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Affiliation(s)
- Endrit Ziu
- Department of Biochemistry and Molecular Biology, College of Medicine, The University of Arkansas for Medical Sciences, Arkansas, USA
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203
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Kiser D, SteemerS B, Branchi I, Homberg JR. The reciprocal interaction between serotonin and social behaviour. Neurosci Biobehav Rev 2012; 36:786-98. [DOI: 10.1016/j.neubiorev.2011.12.009] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2011] [Revised: 11/23/2011] [Accepted: 12/14/2011] [Indexed: 11/27/2022]
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204
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Abstract
Peripheral serotonin, synthesized by tryptophan hydroxylase-1 (TPH(1)), has been shown to play a key role in several physiological functions. Recently, controversy has emerged about whether peripheral serotonin has any effect on bone density and remodeling.We therefore decided to investigate in detail bone remodeling in growing and mature TPH(1) knockout mice (TPH(1)(-/-)). Bone resorption in TPH(1)(-/-) mice, as assessed by biochemical markers and bone histomorphometry, was markedly decreased at both ages. Using bone marrow transplantation, we present evidence that the decrease in bone resorption in TPH(1)(-/-) mice is cell-autonomous. Cultures from TPH(1)(-/-) in the presence of macrophage colony-stimulating factor and receptor activator for NF-KB ligand (RANKL) displayed fewer osteoclasts, and the decreased differentiation could be rescued by adding serotonin. Our data also provide evidence that in the presence of RANKL, osteoclast precursors express TPH(1) and synthesize serotonin. Furthermore, pharmacological inhibition of serotonin receptor 1B with SB224289, and of receptor 2A with ketanserin, also reduced the number of osteoclasts. Our findings reveal that serotonin has an important local action in bone, as it can amplify the effect of RANKL on osteoclastogenesis.
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205
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Gershon MD. Serotonin is a sword and a shield of the bowel: serotonin plays offense and defense. TRANSACTIONS OF THE AMERICAN CLINICAL AND CLIMATOLOGICAL ASSOCIATION 2012; 123:268-80; discussion 280. [PMID: 23303993 PMCID: PMC3540639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The gut contains the bulk of the body's serotonin (5-hydroxytryptamine, 5-HT); nevertheless, the physiological role that enteric 5-HT plays has not been determined. 5-HT is linked to gastrointestinal (GI) motility; increased intraluminal pressure causes enterochromaffin (EC) cells to secrete 5-HT, which stimulates intrinsic primary afferent neurons that initiate peristaltic reflexes. 5-HT is also an enteric neurotransmitter. Surprisingly, deletion of tryptophan hydroxylase-1 (TPH1), upon which 5-HT biosynthesis in EC cells depends, does not alter constitutive GI motility, whereas deletion of TPH2, upon which biosynthesis of neuronal 5-HT depends, slows intestinal transit and accelerates gastric emptying. TPH1 deletion, however, protects mice from experimental inflammation; 5-HT potentiation and TPH2 deletion each make inflammation more severe. Neuronal 5-HT is neuroprotective and recruits stem cells to give rise to new enteric neurons in adult mice. Mucosal 5-HT, therefore, may mobilize inflammatory effectors, which protect the gut from invasion, whereas neuronal 5-HT shields enteric neurons from inflammatory damage.
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Affiliation(s)
- Michael D Gershon
- Department of Pathology and Cell Biology, Columbia University, P&S, 630 West 168th Street, New York, NY 10032, USA.
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206
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Narboux-Nême N, Sagné C, Doly S, Diaz SL, Martin CBP, Angenard G, Martres MP, Giros B, Hamon M, Lanfumey L, Gaspar P, Mongeau R. Severe serotonin depletion after conditional deletion of the vesicular monoamine transporter 2 gene in serotonin neurons: neural and behavioral consequences. Neuropsychopharmacology 2011; 36:2538-50. [PMID: 21814181 PMCID: PMC3194080 DOI: 10.1038/npp.2011.142] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The vesicular monoamine transporter type 2 gene (VMAT2) has a crucial role in the storage and synaptic release of all monoamines, including serotonin (5-HT). To evaluate the specific role of VMAT2 in 5-HT neurons, we produced a conditional ablation of VMAT2 under control of the serotonin transporter (slc6a4) promoter. VMAT2(sert-cre) mice showed a major (-95%) depletion of 5-HT levels in the brain with no major alterations in other monoamines. Raphe neurons contained no 5-HT immunoreactivity in VMAT2(sert-cre) mice but developed normal innervations, as assessed by both tryptophan hydroxylase 2 and 5-HT transporter labeling. Increased 5-HT(1A) autoreceptor coupling to G protein, as assessed with agonist-stimulated [(35)S]GTP-γ-S binding, was observed in the raphe area, indicating an adaptive change to reduced 5-HT transmission. Behavioral evaluation in adult VMAT2(sert-cre) mice showed an increase in escape-like reactions in response to tail suspension and anxiolytic-like response in the novelty-suppressed feeding test. In an aversive ultrasound-induced defense paradigm, VMAT2(sert-cre) mice displayed a major increase in escape-like behaviors. Wild-type-like defense phenotype could be rescued by replenishing intracellular 5-HT stores with chronic pargyline (a monoamine oxidase inhibitor) treatment. Pargyline also allowed some form of 5-HT release, although in reduced amounts, in synaptosomes from VMAT2(sert-cre) mouse brain. These findings are coherent with the notion that 5-HT has an important role in anxiety, and provide new insights into the role of endogenous 5-HT in defense behaviors.
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Affiliation(s)
- Nicolas Narboux-Nême
- INSERM, UMR-S 839, Institut du Fer à Moulin, Paris, France,Université Pierre and Marie Curie, Paris, France
| | - Corinne Sagné
- CNRS UMR8192-Université Paris Descartes, Paris, France
| | - Stephane Doly
- INSERM, UMR-S 839, Institut du Fer à Moulin, Paris, France,Université Pierre and Marie Curie, Paris, France
| | - Silvina L Diaz
- INSERM, UMR-S 839, Institut du Fer à Moulin, Paris, France,Université Pierre and Marie Curie, Paris, France
| | - Cédric B P Martin
- Université Pierre and Marie Curie, Paris, France,INSERM, U894, Paris, France
| | - Gaelle Angenard
- INSERM, UMR-S 839, Institut du Fer à Moulin, Paris, France,Université Pierre and Marie Curie, Paris, France
| | - Marie-Pascale Martres
- Université Pierre and Marie Curie, Paris, France,INSERM, U952, Paris, France,CNRS UMR7224, Paris, France
| | - Bruno Giros
- Université Pierre and Marie Curie, Paris, France,INSERM, U952, Paris, France,CNRS UMR7224, Paris, France,Department of Psychiatry, Douglas Hospital, McGill University, Montreal, Canada
| | - Michel Hamon
- Université Pierre and Marie Curie, Paris, France,INSERM, U894, Paris, France
| | - Laurence Lanfumey
- Université Pierre and Marie Curie, Paris, France,INSERM, U894, Paris, France
| | - Patricia Gaspar
- INSERM, UMR-S 839, Institut du Fer à Moulin, Paris, France,Université Pierre and Marie Curie, Paris, France,INSERM UMR-S 839, Institut du Fer à Moulin, 17 Rue du Fer à Moulin, 75005, Paris, France, Tel: +331 45 87 61 11, Fax: +331 45 87 61 30, E-mail :
| | - Raymond Mongeau
- Université Pierre and Marie Curie, Paris, France,INSERM, U894, Paris, France
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207
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Bonnin A, Levitt P. Fetal, maternal, and placental sources of serotonin and new implications for developmental programming of the brain. Neuroscience 2011; 197:1-7. [PMID: 22001683 DOI: 10.1016/j.neuroscience.2011.10.005] [Citation(s) in RCA: 224] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 09/13/2011] [Accepted: 10/01/2011] [Indexed: 11/16/2022]
Abstract
In addition to its role in neurotransmission, embryonic serotonin (5-HT) has been implicated in the regulation of neurodevelopmental processes. For example, we recently showed that a subset of 5-HT1-receptors expressed in the fetal forebrain mediate a serotonergic modulation of thalamocortical axons response to axon guidance cues, both in vitro and in vivo. This influence of 5-HT signaling on fetal brain wiring raised important questions regarding the source of the ligand during pregnancy. Until recently, it was thought that 5-HT sources impacting brain development arose from maternal transport to the fetus, or from raphe neurons in the brainstem of the fetus. Using genetic mouse models, we uncovered previously unknown differences in 5-HT accumulation between the fore- and hindbrain during early and late fetal stages, through an exogenous source of 5-HT. Using additional genetic strategies, a new technology for studying placental biology ex vivo, and direct manipulation of placental neosynthesis, we investigated the nature of this exogenous source and uncovered a placental 5-HT synthetic pathway from a maternal tryptophan precursor, in both mice and humans. These results implicate a new, direct role for placental metabolic pathways in modulating fetal brain development and suggest an important role for maternal-placental-fetal interactions and 5-HT in the fetal programming of adult mental disorders.
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Affiliation(s)
- A Bonnin
- Silvio O. Conte Neuroscience Research Center, Vanderbilt University Medical Center, Nashville, TN 37221, USA.
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208
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Fernandez SP, Gaspar P. Investigating anxiety and depressive-like phenotypes in genetic mouse models of serotonin depletion. Neuropharmacology 2011; 62:144-54. [PMID: 21945798 DOI: 10.1016/j.neuropharm.2011.08.049] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 08/25/2011] [Accepted: 08/29/2011] [Indexed: 01/24/2023]
Abstract
Emotional disorders such as depression, panic attacks, generalized anxiety, phobias and post-traumatic stress have been associated to decreased serotonin (5-HT) function, based on the positive effects of treatments that enhance 5-HT neurotransmission. However, it has been difficult to establish a primary role for 5-HT deficiency in these diseases, making preclinical models particularly useful. Over the last ten years a variety of genetic mouse models of 5-HT depletion have been produced, complementing previous pharmacologically-based models. Initial models hindered the differentiation of the raphe 5-HT neurons, while more recently produced models suppressed 5-HT production or incapacitated 5-HT vesicular packaging and release in normally developed raphe neurons. Here, we provide an overview of 11 genetic mouse models with lowered 5-HT transmission and summarize the available behavioural investigations concerning their anxiety and depression phenotypes. Although these studies are still ongoing, some common anxiety-related traits and behavioural phenotypes have emerged. Most studies have reported decreased innate anxiety to novelty but heightened fear responses to conditioned aversive cues. This complex phenotype is in general agreement with the proposed dual function of 5-HT in modulating different defensive behaviours. Surprisingly, the depressive-like behaviours have been less studied and, so far, did not yield a consistent phenotype in standard tests. Future studies should be conducted using more ethological relevant models to conclude on the causal role of 5-HT depletion in depression. This review also describes the differences in level and regional distribution of 5-HT depletion among the available mouse models, which could contribute to the diverse phenotypes observed. This article is part of a Special Issue entitled 'Anxiety and Depression'.
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209
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Essential roles of enteric neuronal serotonin in gastrointestinal motility and the development/survival of enteric dopaminergic neurons. J Neurosci 2011; 31:8998-9009. [PMID: 21677183 DOI: 10.1523/jneurosci.6684-10.2011] [Citation(s) in RCA: 284] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The gut contains a large 5-HT pool in enterochromaffin (EC) cells and a smaller 5-HT pool in the enteric nervous system (ENS). During development, enteric neurons are generated asynchronously. We tested hypotheses that serotonergic neurons, which arise early, affect development/survival of later-born dopaminergic, GABAergic, nitrergic, and calcitonin gene-related peptide-expressing neurons and are essential for gastrointestinal motility. 5-HT biosynthesis depends on tryptophan hydroxylase 1 (TPH1) in EC cells and on TPH2 in neurons; therefore, mice lacking TPH1 and/or TPH2 distinguish EC-derived from neuronal 5-HT. Deletion of TPH2, but not TPH1, decreased myenteric neuronal density and proportions of dopaminergic and GABAergic neurons but did not affect the extrinsic sympathetic innervation of the gut; intestinal transit slowed in mice lacking TPH2 mice, but gastric emptying accelerated. Isolated enteric crest-derived cells (ENCDCs) expressed the serotonin reuptake transporter (SERT) and 15 subtypes of 5-HT receptor. Addition of 5-HT to cultures of isolated ENCDCs promoted total and dopaminergic neuronal development. Rings of SERT-immunoreactive terminal axons surrounded myenteric dopaminergic neurons and SERT knock-out increased intestinal levels of dopamine metabolites, implying that enteric dopaminergic neurons receive a serotonergic innervation. Observations suggest that constitutive gastrointestinal motility depends more on neuronal than EC cell serotonin; moreover, serotonergic neurons promote development/survival of some classes of late-born enteric neurons, including dopaminergic neurons, which appear to innervate and activate in the adult ENS.
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210
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Huynh ML, Rivkin E, Mui R, Cordes SP. A tryptophan hydroxlyase 1 reporter that directs Cre recombinase extinguishable placental alkaline phosphatase expression in serotonergic (5-HT) neurons and peripheral tissues. Genesis 2011; 49:851-61. [DOI: 10.1002/dvg.20746] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 03/01/2011] [Accepted: 03/02/2011] [Indexed: 11/09/2022]
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211
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Brown PM, Drossman DA, Wood AJJ, Cline GA, Frazier KS, Jackson JI, Bronner J, Freiman J, Zambrowicz B, Sands A, Gershon MD. The tryptophan hydroxylase inhibitor LX1031 shows clinical benefit in patients with nonconstipating irritable bowel syndrome. Gastroenterology 2011; 141:507-16. [PMID: 21684281 PMCID: PMC4905727 DOI: 10.1053/j.gastro.2011.05.005] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 03/21/2011] [Accepted: 05/05/2011] [Indexed: 02/06/2023]
Abstract
BACKGROUND & AIMS Serotonin (5-hydroxytryptamine [5-HT]) has an important role in gastrointestinal function. LX1031 is an oral, locally acting, small molecule inhibitor of tryptophan hydroxylase (TPH). Local inhibition of TPH in the gastrointestinal tract might reduce mucosal production of serotonin (5-HT) and be used to treat patients with nonconstipating irritable bowel syndrome (IBS). METHODS We evaluated 2 dose levels of LX1031 (250 mg or 1000 mg, given 4 times/day) in a 28-day, multicenter, randomized, double-blind, placebo-controlled study of 155 patients with nonconstipating IBS. 5-hydroxyindoleacetic acid (5-HIAA), a biomarker of pharmacodynamic activity, was measured in urine samples at baseline (24 hours after LX1031 administration), and at weeks 4 and 6 (n = 76). RESULTS Each dose of LX1031 was safe and well-tolerated. The primary efficacy end point, relief of IBS pain and discomfort, improved significantly in patients given 1000 mg LX1031 (25.5%), compared with those given placebo, at week 1 (P = .018); with nonsignificant improvements at weeks 2, 3, and 4 (17.9%, 16.3%, and 11.6%, respectively). Symptom improvement correlated with a dose-dependent reduction in 5-HIAA, a marker for TPH inhibition, from baseline until week 4. This suggests the efficacy of LX1031 is related to the extent of inhibition of 5-HT biosynthesis. Stool consistency significantly improved, compared with the group given placebo, at weeks 1 and 4 (P < .01) and at week 2 (P < .001). CONCLUSIONS In a phase 2 study, LX1031 was well tolerated, relieving symptoms and increasing stool consistency in patients with nonconstipating IBS. Symptom relief was associated with reduced levels of 5-HIAA in urine samples. This marker might be used to identify patients with nonconstipating IBS who respond to inhibitors of 5-HT synthesis.
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Affiliation(s)
| | - Douglas A. Drossman
- UNC Center for Functional GI and Motility Disorders, University of North Carolina School of Medicine, Division of Gastroenterology and Hepatology, Chapel Hill, North Carolina
| | - Alastair J. J. Wood
- Symphony Capital, Weill Cornell Medical College, Department of Medicine, Department of Pharmacology
| | - Gary A. Cline
- Icon Clinical Research, Department of Biostatistics, North Wales, Pennsylvania
| | | | | | | | - Joel Freiman
- Lexicon Pharmaceuticals, Inc, The Woodlands, Texas
| | | | - Arthur Sands
- Lexicon Pharmaceuticals, Inc, The Woodlands, Texas
| | - Michael D. Gershon
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York
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212
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Ineffective erythropoiesis with reduced red blood cell survival in serotonin-deficient mice. Proc Natl Acad Sci U S A 2011; 108:13141-6. [PMID: 21788492 DOI: 10.1073/pnas.1103964108] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Serotonin (5-HT) has long been recognized as a neurotransmitter in the central nervous system, where it modulates a variety of behavioral functions. Availability of 5-HT depends on the expression of the enzyme tryptophan hydroxylase (TPH), and the recent discovery of a dual system for 5-HT synthesis in the brain (TPH2) and periphery (TPH1) has renewed interest in studying the potential functions played by 5-HT in nonnervous tissues. Moreover, characterization of the TPH1 knockout mouse model (TPH1(-/-)) led to the identification of unsuspected roles for peripheral 5-HT, revealing the importance of this monoamine in regulating key physiological functions outside the brain. Here, we present in vivo data showing that mice deficient in peripheral 5-HT display morphological and cellular features of ineffective erythropoiesis. The central event occurs in the bone marrow where the absence of 5-HT hampers progression of erythroid precursors expressing 5-HT(2A) and 5-HT(2B) receptors toward terminal differentiation. In addition, red blood cells from 5-HT-deficient mice are more sensitive to macrophage phagocytosis and have a shortened in vivo half-life. The combination of these two defects causes TPH1(-/-) animals to develop a phenotype of macrocytic anemia. Direct evidence for a 5-HT effect on erythroid precursors is provided by supplementation of the culture medium with 5-HT that increases the proliferative capacity of both 5-HT-deficient and normal cells. Our thorough analysis of TPH1(-/-) mice provides a unique model of morphological and functional aberrations of erythropoiesis and identifies 5-HT as a key factor for red blood cell production and survival.
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213
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Hong KW, Weiss A, Morimura N, Udono T, Hayasaka I, Humle T, Murayama Y, Ito S, Inoue-Murayama M. Polymorphism of the tryptophan hydroxylase 2 (TPH2) gene is associated with chimpanzee neuroticism. PLoS One 2011; 6:e22144. [PMID: 21765945 PMCID: PMC3135609 DOI: 10.1371/journal.pone.0022144] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 06/16/2011] [Indexed: 11/19/2022] Open
Abstract
In the brain, serotonin production is controlled by tryptophan hydroxylase 2 (TPH2), a genotype. Previous studies found that mutations on the TPH2 locus in humans were associated with depression and studies of mice and studies of rhesus macaques have shown that the TPH2 locus was involved with aggressive behavior. We previously reported a functional single nucleotide polymorphism (SNP) in the form of an amino acid substitution, Q468R, in the chimpanzee TPH2 gene coding region. In the present study we tested whether this SNP was associated with neuroticism in captive and wild-born chimpanzees living in Japan and Guinea, respectively. Even after correcting for multiple tests (Bonferroni p = 0.05/6 = 0.008), Q468R was significantly related to higher neuroticism (β = 0.372, p = 0.005). This study is the first to identify a genotype linked to a personality trait in chimpanzees. In light of the prior studies on humans, mice, and rhesus macaques, these findings suggest that the relationship between neuroticism and TPH2 has deep phylogenetic roots.
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Affiliation(s)
- Kyung-Won Hong
- The United Graduate School of Agricultural Science, Gifu University, Gifu, Japan
| | - Alexander Weiss
- Scottish Primate Research Group, Department of Psychology, School of Philosophy, Psychology and Language Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | | | - Toshifumi Udono
- The Chimpanzee Sanctuary Uto, Sanwa Kagaku Kenkyusho co., Ltd., Uto, Kumamoto, Japan
| | - Ikuo Hayasaka
- The Chimpanzee Sanctuary Uto, Sanwa Kagaku Kenkyusho co., Ltd., Uto, Kumamoto, Japan
| | - Tatyana Humle
- School of Anthropology and Conservation, University of Kent. Canterbury, Kent, United Kingdom
| | | | - Shin'ichi Ito
- Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
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214
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Li N, Ghia JE, Wang H, McClemens J, Cote F, Suehiro Y, Mallet J, Khan WI. Serotonin activates dendritic cell function in the context of gut inflammation. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 178:662-71. [PMID: 21281798 DOI: 10.1016/j.ajpath.2010.10.028] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 09/16/2010] [Accepted: 10/19/2010] [Indexed: 01/06/2023]
Abstract
Mucosal inflammation in the gut is characterized by infiltration of innate and adaptive immune cells and by an alteration in serotonin-producing enterochromaffin cells. We investigated the role of serotonin in the function of dendritic cells (DCs) and sequential T-cell activation in relation to generation of gut inflammation. DCs isolated from tryptophan hydroxylase-1-deficient (TPH1(-/-)) mice, which have reduced serotonin in the gut, and wild-type (TPH1(+/+)) mice with or without dextran sulfate sodium (DSS)-induced colitis were stimulated with lipopolysaccharide to assess interleukin-12 (IL-12) production. Isolated DCs from TPH1(+/+) and TPH1(-/-) mice were also cocultured with CD4(+) T cells of naive TPH1(+/+) mice to assess the role of serotonin in priming T cells. In addition, serotonin-pulsed DCs were transferred to TPH1(-/-) mice to assess the effect on DSS-induced colitis. Consistent with a reduced severity of colitis, DCs from DSS-induced TPH1(-/-) mice produced less IL-12 compared with the TPH1(+/+) mice. In vitro serotonin stimulation restored the cytokine production from TPH1(-/-) DCs and adoptive transfer of serotonin-pulsed DCs into TPH1(-/-) up-regulated colitis. Furthermore, CD4(+) T cells primed by TPH1(-/-) DCs produce reduced the levels of IL-17 and interferon-γ. This study provides novel information on serotonin-mediated immune signaling and promotion of interactions between innate and adaptive immune responses in the context of gut inflammation, which may ultimately lead to improved strategies to combat gut inflammatory disorders.
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Affiliation(s)
- Nan Li
- Farncombe Family Digestive Health Research Institute, Department of Pathology, McMaster University, Hamilton, Ontario, Canada
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215
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Mancino M, Ametller E, Gascón P, Almendro V. The neuronal influence on tumor progression. Biochim Biophys Acta Rev Cancer 2011; 1816:105-18. [PMID: 21616127 DOI: 10.1016/j.bbcan.2011.04.005] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2011] [Revised: 04/28/2011] [Accepted: 04/29/2011] [Indexed: 01/11/2023]
Abstract
Nerve fibers accompany blood and lymphatic vessels all over the body. An extensive amount of knowledge has been obtained with regard to tumor angiogenesis and tumor lymphangiogenesis, yet little is known about the potential biological effects of "neoneurogenesis". Cancer cells can exploit the advantage of the factors released by the nerve fibers to generate a positive microenvironment for cell survival and proliferation. At the same time, they can stimulate the formation of neurites by secreting neurotrophic factors and axon guidance molecules. The neuronal influence on the biology of a neoplasm was initially described several decades ago. Since then, an increasing amount of experimental evidence strongly suggests the existence of reciprocal interactions between cancer cells and nerves in humans. Moreover, researchers have been able to demonstrate a crosstalk between cancer cells and nerve fibers as a strategy for survival. Despite all these evidence, a lot remains to be done in order to clarify the role of neurotransmitters, neuropeptides, and their associated receptor-initiated signaling pathways in the development and progression of cancer, and response to therapy. A global-wide characterization of the neurotransmitters or neuropeptides present in the tumor microenvironment would provide insights into the real biological influences of the neuronal tissue on tumor progression. This review is intended to discuss our current understanding of neurosignaling in cancer and its potential implications on cancer prevention and therapy. The review will focus on the soluble factors released by cancer cells and nerve endings, their biological effects and their potential relevance in the treatment of cancer.
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Affiliation(s)
- Mario Mancino
- Department of Medical Oncology, Centro Esther Koplowitz CEK, Institut d' investigacions Biomèdiques August Pi i Sunyer IDIBAPS, Hospital Clinic, Medical School, University of Barcelona, Barcelona, Spain
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216
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Waider J, Araragi N, Gutknecht L, Lesch KP. Tryptophan hydroxylase-2 (TPH2) in disorders of cognitive control and emotion regulation: a perspective. Psychoneuroendocrinology 2011; 36:393-405. [PMID: 21257271 DOI: 10.1016/j.psyneuen.2010.12.012] [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: 08/02/2010] [Revised: 12/22/2010] [Accepted: 12/23/2010] [Indexed: 01/24/2023]
Abstract
Based on genetic variation, there is accumulating evidence that altered function of tryptophan hydroxylase-2 (TPH2), the enzyme critical for synthesis of serotonin (5-HT) in the brain, plays a role in anxiety-, aggression- and depression-related personality traits and in the pathogenesis of disorders featuring deficits in cognitive control and emotion regulation. Here, we appraise the genetic and neurobiological evidence to illustrate the critical role of TPH2 in central 5-HT system function and in the pathophysiology of a wide spectrum of disorders of cognitive control and emotion regulation, ranging from depression to attention-deficit/hyperactivity disorder (ADHD), a phenotype commonly associated with difficulties in the control of emotion and with a high co-morbidity of depression. Findings from psychophysiological and functional imaging studies are indicative of various TPH2 polymorphisms directly influencing serotonergic function and thus impacting on mood disorders and on the response to antidepressant treatment. Especially a combination with uncontrollable stress seems to potentiate these effects linking gene-environment interaction directly with behavioral dysfunction in human and animal models. TPH2-deficient mice display alterations in anxiety-like behavior which is accompanied by adaptational changes of 5-HT(1A) receptors and its associated signaling pathway. Mouse models in conjunction with cognitive neuroscience approaches in humans are providing unexpected results and it may well be that future research on TPH2 will provide an entirely new view of 5-HT in brain development and function related to neuropsychiatric disorders.
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Affiliation(s)
- Jonas Waider
- Molecular Psychiatry, Laboratory of Translational Neuroscience, Department of Psychiatry, Psychosomatics, and Psychotherapy, University of Wuerzburg, Fuechsleinstrasse 15, 97080 Wuerzburg, Germany
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Altered gene expression in pulmonary tissue of tryptophan hydroxylase-1 knockout mice: implications for pulmonary arterial hypertension. PLoS One 2011; 6:e17735. [PMID: 21464983 PMCID: PMC3064573 DOI: 10.1371/journal.pone.0017735] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 02/10/2011] [Indexed: 11/19/2022] Open
Abstract
The use of fenfluramines can increase the risk of developing pulmonary arterial hypertension (PAH) in humans, but the mechanisms responsible are unresolved. A recent study reported that female mice lacking the gene for tryptophan hydroxylase-1 (Tph1(−/−) mice) were protected from PAH caused by chronic dexfenfluramine, suggesting a pivotal role for peripheral serotonin (5-HT) in the disease process. Here we tested two alternative hypotheses which might explain the lack of dexfenfluramine-induced PAH in Tph1(−/−) mice. We postulated that: 1) Tph1(−/−) mice express lower levels of pulmonary 5-HT transporter (SERT) when compared to wild-type controls, and 2) Tph1(−/−) mice display adaptive changes in the expression of non-serotonergic pulmonary genes which are implicated in PAH. SERT was measured using radioligand binding methods, whereas gene expression was measured using microarrays followed by quantitative real time PCR (qRT-PCR). Contrary to our first hypothesis, the number of pulmonary SERT sites was modestly up-regulated in female Tph1(−/−) mice. The expression of 51 distinct genes was significantly altered in the lungs of female Tph1(−/−) mice. Consistent with our second hypothesis, qRT-PCR confirmed that at least three genes implicated in the pathogenesis of PAH were markedly up-regulated: Has2, Hapln3 and Retlna. The finding that female Tph1(−/−) mice are protected from dexfenfluramine-induced PAH could be related to compensatory changes in pulmonary gene expression, in addition to reductions in peripheral 5-HT. These observations emphasize the intrinsic limitation of interpreting data from studies conducted in transgenic mice that are not fully characterized.
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218
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Browne CA, Clarke G, Dinan TG, Cryan JF. Differential stress-induced alterations in tryptophan hydroxylase activity and serotonin turnover in two inbred mouse strains. Neuropharmacology 2011; 60:683-91. [DOI: 10.1016/j.neuropharm.2010.11.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 11/23/2010] [Accepted: 11/24/2010] [Indexed: 10/18/2022]
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219
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Li Z, Caron MG, Blakely RD, Margolis KG, Gershon MD. Dependence of serotonergic and other nonadrenergic enteric neurons on norepinephrine transporter expression. J Neurosci 2010; 30:16730-40. [PMID: 21148012 PMCID: PMC3066093 DOI: 10.1523/jneurosci.2276-10.2010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The norepinephrine transporter (NET), which is expressed on the plasma membranes of noradrenergic neurons, is important in terminating neurotransmission. The noradrenergic sympathetic neurons that innervate the bowel express NET, but they are extrinsic and their cell bodies are not components of the enteric nervous system (ENS). Subsets of neurons were nevertheless found in the murine ENS that express transcripts encoding NET, NET protein, and dopamine β-hydroxylase; these neurons lack tyrosine hydroxylase (TH) and thus are not catecholaminergic. Enteric NET expression, moreover, preceded the ingrowth of sympathetic axons during development and did not disappear when the gut was extrinsically denervated. Transiently catecholaminergic (TC), neural crest-derived precursors of enteric neurons expressed NET at embryonic day 10 (E10) and NET expression in the fetal gut peaked coincidentally with early neurogenesis at E12. Serotonergic neurons, which are born early from TC progenitors, were found to express NET in the adult ENS, as did also other early-born neurons containing calretinin or neuronal nitric oxide synthase (nNOS) immunoreactivities. NET was not expressed in TH-immunoreactive dopaminergic neurons, which are born perinatally. Genetic deletion of NET almost eliminated tryptophan hydroxylase 2 expression and significantly reduced the numbers of total, 5-HT- and calretinin-immunoreactive enteric neurons, without affecting the immunoreactivities of nNOS or TH. These observations indicate that TC precursors of subsets of noncatecholaminergic enteric neurons express NET that persists in the successors of these cells despite their loss of TH. NET expression is essential for development and/or survival of some (5-HT- and calretinin-expressing), but not all (nNOS-expressing), of these neurons.
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Affiliation(s)
- Zhishan Li
- Department of Pathology and Cell Biology, Columbia University, New York, New York 10032, USA.
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220
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Schraenen A, Lemaire K, de Faudeur G, Hendrickx N, Granvik M, Van Lommel L, Mallet J, Vodjdani G, Gilon P, Binart N, in’t Veld P, Schuit F. Placental lactogens induce serotonin biosynthesis in a subset of mouse beta cells during pregnancy. Diabetologia 2010; 53:2589-99. [PMID: 20938637 PMCID: PMC2974930 DOI: 10.1007/s00125-010-1913-7] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 08/17/2010] [Indexed: 12/04/2022]
Abstract
AIMS/HYPOTHESIS Upregulation of the functional beta cell mass is required to match the physiological demands of mother and fetus during pregnancy. This increase is dependent on placental lactogens (PLs) and prolactin receptors, but the mechanisms underlying these events are only partially understood. We studied the mRNA expression profile of mouse islets during pregnancy to gain a better insight into these changes. METHODS RNA expression was measured ex vivo via microarrays and quantitative RT-PCR. In vivo observations were extended by in vitro models in which ovine PL was added to cultured mouse islets and MIN6 cells. RESULTS mRNA encoding both isoforms of the rate-limiting enzyme of serotonin biosynthesis, tryptophan hydroxylase (TPH), i.e. Tph1 and Tph2, were strongly induced (fold change 25- to 200-fold) during pregnancy. This induction was mimicked by exposing islets or MIN6 cells to ovine PLs for 24 h and was dependent on janus kinase 2 and signal transducer and activator of transcription 5. Parallel to Tph1 mRNA and protein induction, islet serotonin content increased to a peak level that was 200-fold higher than basal. Interestingly, only a subpopulation of the beta cells was serotonin-positive in vitro and in vivo. The stored serotonin pool in pregnant islets and PL-treated MIN6 cells was rapidly released (turnover once every 2 h). CONCLUSIONS/INTERPRETATION A very strong lactogen-dependent upregulation of serotonin biosynthesis occurs in a subpopulation of mouse islet beta cells during pregnancy. Since the newly formed serotonin is rapidly released, this lactogen-induced beta cell function may serve local or endocrine tasks, the nature of which remains to be identified.
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Affiliation(s)
- A. Schraenen
- Gene Expression Unit, Department of Molecular Cell Biology, Katholieke Universiteit Leuven, O&N1, Herestraat 49 bus 901, 3000 Leuven, Belgium
| | - K. Lemaire
- Gene Expression Unit, Department of Molecular Cell Biology, Katholieke Universiteit Leuven, O&N1, Herestraat 49 bus 901, 3000 Leuven, Belgium
| | - G. de Faudeur
- Gene Expression Unit, Department of Molecular Cell Biology, Katholieke Universiteit Leuven, O&N1, Herestraat 49 bus 901, 3000 Leuven, Belgium
| | - N. Hendrickx
- Gene Expression Unit, Department of Molecular Cell Biology, Katholieke Universiteit Leuven, O&N1, Herestraat 49 bus 901, 3000 Leuven, Belgium
| | - M. Granvik
- Gene Expression Unit, Department of Molecular Cell Biology, Katholieke Universiteit Leuven, O&N1, Herestraat 49 bus 901, 3000 Leuven, Belgium
| | - L. Van Lommel
- Gene Expression Unit, Department of Molecular Cell Biology, Katholieke Universiteit Leuven, O&N1, Herestraat 49 bus 901, 3000 Leuven, Belgium
| | - J. Mallet
- Centre de Recherche de l’Institut du Cerveau et de la Moelle épinière, CNRS UMR-7225, INSERM UMRS-975, Université Pierre et Marie Curie, Paris, France
| | - G. Vodjdani
- Centre de Recherche de l’Institut du Cerveau et de la Moelle épinière, CNRS UMR-7225, INSERM UMRS-975, Université Pierre et Marie Curie, Paris, France
| | - P. Gilon
- Unit of Endocrinology and Metabolism, Faculty of Medicine, Université de Louvain, 1000 Brussels, Belgium
| | - N. Binart
- Inserm U845, Paris, France
- Faculté de Médecine, Université Paris Descartes, Paris, France
| | - P. in’t Veld
- Department of Pathology, Vrije Universiteit Brussel, Jette, Belgium
| | - F. Schuit
- Gene Expression Unit, Department of Molecular Cell Biology, Katholieke Universiteit Leuven, O&N1, Herestraat 49 bus 901, 3000 Leuven, Belgium
- Center for Computational Systems Biology, SymBioSys, Katholieke Universiteit Leuven, Leuven, Belgium
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221
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Mercado CP, Kilic F. Molecular mechanisms of SERT in platelets: regulation of plasma serotonin levels. Mol Interv 2010; 10:231-41. [PMID: 20729489 DOI: 10.1124/mi.10.4.6] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The serotonin transporter (SERT) on platelets is a primary mechanism for serotonin (5HT) uptake from the blood plasma. Alteration in plasma 5HT level is associated with a number of cardiovascular diseases and disorders. Therefore, the regulation of the transporter's activity represents a key mechanism to stabilize the concentration of plasma 5HT. There is a biphasic relationship between plasma 5HT elevation, loss of surface SERT, and depletion of platelet 5HT. Specifically, in platelets, plasma membrane SERT levels and platelet 5HT uptake initially rise as plasma 5HT levels are increased but then fall below normal as the plasma 5HT level continues to rise. Therefore, we propose that elevated plasma 5HT limits its own uptake in platelets by down-regulating SERT as well as modifying the characteristics of SERT partners in the membrane trafficking pathway. This review will summarize current findings regarding the biochemical mechanisms by which elevated 5HT downregulates the expression of SERT on the platelet membrane. Intriguing aspects of this regulation include the intracellular interplay of SERT with the small G protein Rab4 and the concerted 5HT-mediated phosphorylation of vimentin.
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Affiliation(s)
- Charles P Mercado
- Department of Biochemistry and Molecular Biology College of Medicine, The University of Arkansas for Medical Sciences Little Rock, Arkansas 72205, USA
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222
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Scruggs SM, Disatian S, Orton EC. Serotonin transmembrane transporter is down-regulated in late-stage canine degenerative mitral valve disease. J Vet Cardiol 2010; 12:163-9. [PMID: 21036114 DOI: 10.1016/j.jvc.2010.06.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 05/25/2010] [Accepted: 06/07/2010] [Indexed: 12/16/2022]
Abstract
OBJECTIVE To compare expression of the serotonin transmembrane transporter (SERT) in normal, early-stage degenerative, and late-stage degenerative canine mitral valve disease. ANIMALS 24 post-mortem canine mitral valves. METHODS SERT expression was determined in canine normal (n = 8), early-stage degenerative (n = 8), and late-stage degenerative (n = 8) mitral valves by immunohistochemistry (IHC) and immunoblot (IB) analyses. RESULTS SERT was expressed in valve interstitial cells of all layers of normal and early-stage degenerative mitral valves based on IHC. SERT was markedly down-regulated in valve interstitial cells, but not valve endothelial cells, of late-stage degenerative mitral valves. SERT expression was significantly decreased in late-stage compared to normal and early-stage degenerative mitral valves based on IB analysis (P < 0.05). CONCLUSIONS Down-regulation of SERT expression occurs in valve interstitial cells of late-stage, but not early-stage, canine degenerative mitral valves. Down-regulation of SERT could enhance the recently speculated role of serotonin in canine DMVD by decreasing serotonin metabolism and increasing interaction with its receptor. Down-regulation of SERT likely does not play an initiating role in canine DMVD since it does not occur in early-stage disease.
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Affiliation(s)
- Sarah M Scruggs
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
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223
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Monassier L, Laplante MA, Ayadi T, Doly S, Maroteaux L. Contribution of gene-modified mice and rats to our understanding of the cardiovascular pharmacology of serotonin. Pharmacol Ther 2010; 128:559-67. [PMID: 20828585 DOI: 10.1016/j.pharmthera.2010.08.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
This review focuses on new insights provided by gene-modified animals into the cardiovascular pharmacology of serotonin. During their development, mice mutant for tryptophan hydroxylase 1 and lacking peripheral serotonin, or mutant for 5-HT(2B) receptors, display cardiac defects and dilated cardiomyopathy. The 5-HT(4) receptor is important for the maturation of cardiac conduction. In fact, transgenic approaches have revealed that adult cardiac status is strongly influenced by maternal serotonin. Serotonin has long been known to be a vasoconstrictor in adult physiology. Analysis of animals knocked-out for the serotonin transporter suggested a role in blood pressure control and revealed an effect of 5-HT(2B) receptor antagonists in hypertension. In the lung vasculature, mice lacking the 5-HT(2B) receptor gene that are exposed to chronic hypoxia are resistant to pulmonary hypertension, while 5-HT(1B) receptor and serotonin transporter mutant animals show partial resistance. In platelets, mutant mice revealed that serotonin transporter regulates not only the mechanisms by which serotonin is packaged and secreted but also platelet aggregation. Studies looking at adult cardiac remodeling showed that mice lacking the 5-HT(2B) receptor gene were protected from cardiac hypertrophy. Their fibroblasts were unable to secrete cytokines. Crossing these animals with mice overexpressing the receptor in cardiomyocytes revealed the contribution of cardiac fibroblasts and 5-HT(2B) receptors to cardiac hypertrophy. In mice lacking the monoamine oxidase-A gene, the role of serotonin degradation in cardiac hypertrophy was confirmed. Works with gene-modified animals has contributed strongly to the re-evaluation of the influence of serotonin on cardiovascular regulation, though several unknowns remain to be investigated.
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Affiliation(s)
- Laurent Monassier
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, Physiopathologie et Médecine Translationnelle EA 4438, Faculté de Médecine, 11 rue Humann, 67085 Strasbourg, France.
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224
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Trowbridge S, Narboux-Nême N, Gaspar P. Genetic models of serotonin (5-HT) depletion: what do they tell us about the developmental role of 5-HT? Anat Rec (Hoboken) 2010; 294:1615-23. [PMID: 20818612 DOI: 10.1002/ar.21248] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Accepted: 07/09/2010] [Indexed: 11/10/2022]
Abstract
A large number of hyposerotonergic genetic models have been generated over the past few years. Serotonin (5-HT) depletion has been obtained via targeting of genes involved in 5-HT synthesis (Tph1 and Tph2), specification and determination of the 5-HT phenotype during development (GATA3, Pet1, and Lmx1b), and 5-HT storage or clearance (Vmat2 and SERT). Here we review these various models from a developmental perspective, beginning with a description of the sources of 5-HT during development. We then summarize the neurological and behavioral alterations that have been observed in the genetic hyposerotonergic models. Although these models appear to have normal brain development and do not exhibit any gross morphological defects, problems in somatic growth and physiological functions have been observed. Abnormal adult behavior is also seen, although whether it results from depletion of 5-HT during development or functional 5-HT deficiencies in adult life remains unclear. Evidence from these hyposerotonergic models suggests that the developing brain may not need 5-HT for the establishment of general organization and structure. However, central 5-HT appears to be necessary for postnatal body growth, maturation of respiratory and vegetative control, and possibly for the development of normal adult behavior.
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225
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Zhang Y, Zhang C, Yuan G, Yao J, Cheng Z, Liu C, Liu Q, Wan G, Shi G, Cheng Y, Ling Y, Li K. Effect of tryptophan hydroxylase-2 rs7305115 SNP on suicide attempts risk in major depression. Behav Brain Funct 2010; 6:49. [PMID: 20738857 PMCID: PMC2939585 DOI: 10.1186/1744-9081-6-49] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Accepted: 08/25/2010] [Indexed: 02/01/2023] Open
Abstract
Background Suicide and major depressive disorders (MDD) are strongly associated, and genetic factors are responsible for at least part of the variability in suicide risk. We investigated whether variation at the tryptophan hydroxylase-2 (TPH2) gene rs7305115 SNP may predispose to suicide attempts in MDD. Methods We genotyped TPH2 gene rs7305115 SNP in 215 MDD patients with suicide and matched MDD patients without suicide. Differences in behavioral and personality traits according to genotypic variation were investigated by logistic regression analysis. Results There were no significant differences between MDD patients with suicide and controls in genotypic (AG and GG) frequencies for rs7305115 SNP, but the distribution of AA genotype differed significantly (14.4% vs. 29.3%, p < 0.001). The G-allele frequency was significantly higher in cases than control group (58.1% vs.45.6%, p < 0.001), but the A-allele carrier indicated a decreased trend in MDD with suicide behaviors than control group (41.9% vs.54.4%, p < 0.001). The multivariate logistic regression analysis indicated that TPH2 rs7305115 AA (OR 0.33, 95% CI 0.22-0.99), family history of suicide (OR 2.98, 95% CI 1.17-5.04), negative life events half year ago (OR 6.64, 95% CI 2.48-11.04) and hopelessness (OR 7.68, 95% CI 5.79-13.74) were significantly associated with the suicide behaviors in MDD patients. Conclusions The study suggested that hopelessness, negative life events and family history of suicide were risk factors of attempted suicide in MDD while the TPH2 rs7305115A remained a significant protective predictor of suicide attempts.
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Affiliation(s)
- Yuqi Zhang
- Wuxi Psychiatric Hospital, Nanjing Medical University, Wuxi, China.
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226
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Dickson EJ, Heredia DJ, Smith TK. Critical role of 5-HT1A, 5-HT3, and 5-HT7 receptor subtypes in the initiation, generation, and propagation of the murine colonic migrating motor complex. Am J Physiol Gastrointest Liver Physiol 2010; 299:G144-57. [PMID: 20413719 PMCID: PMC2904117 DOI: 10.1152/ajpgi.00496.2009] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The colonic migrating motor complex (CMMC) is necessary for fecal pellet propulsion in the murine colon. We have previously shown that 5-hydroxytryptamine (5-HT) released from enterochromaffin cells activates 5-HT(3) receptors on the mucosal processes of myenteric Dogiel type II neurons to initiate the events underlying the CMMC. Our aims were to further investigate the roles of 5-HT(1A), 5-HT(3), and 5-HT(7) receptor subtypes in generating and propagating the CMMC using intracellular microelectrodes or tension recordings from the circular muscle (CM) in preparations with and without the mucosa. Spontaneous CMMCs were recorded from the CM in isolated murine colons but not in preparations without the mucosa. In mucosaless preparations, ondansetron (3 microM; 5-HT(3) antagonist) plus hexamethonium (100 microM) completely blocked spontaneous inhibitory junction potentials, depolarized the CM. Ondansetron blocked the preceding hyperpolarization associated with a CMMC. Spontaneous CMMCs and CMMCs evoked by spritzing 5-HT (10 and 100 microM) or nerve stimulation in preparations without the mucosa were blocked by SB 258719 or SB 269970 (1-5 microM; 5-HT(7) antagonists). Both NAN-190 and (S)-WAY100135 (1-5 microM; 5-HT(1A) antagonists) blocked spontaneous CMMCs and neurally evoked CMMCs in preparations without the mucosa. Both NAN-190 and (S)-WAY100135 caused an atropine-sensitive depolarization of the CM. The precursor of 5-HT, 5-hydroxytryptophan (5-HTP) (10 microM), and 5-carboxamidotryptamine (5-CT) (5 microM; 5-HT(1/5/7) agonist) increased the frequency of spontaneous CMMCs. 5-HTP and 5-CT also induced CMMCs in preparations with and without the mucosa, which were blocked by SB 258719. 5-HT(1A), 5-HT(3), and 5-HT(7) receptors, most likely on Dogiel Type II/AH neurons, are important in initiating, generating, and propagating the CMMC. Tonic inhibition of the CM appears to be driven by ongoing activity in descending serotonergic interneurons; by activating 5-HT(7) receptors on AH neurons these interneurons also contribute to the generation of the CMMC.
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Affiliation(s)
- Eamonn J. Dickson
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Dante J. Heredia
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Terence K. Smith
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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227
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Cianchetta G, Stouch T, Yu W, Shi ZC, Tari LW, Swanson RV, Hunter MJ, Hoffman ID, Liu Q. Mechanism of Inhibition of Novel Tryptophan Hydroxylase Inhibitors Revealed by Co-crystal Structures and Kinetic Analysis. CURRENT CHEMICAL GENOMICS 2010; 4:19-26. [PMID: 20556201 PMCID: PMC2885594 DOI: 10.2174/1875397301004010019] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 02/26/2010] [Accepted: 02/26/2010] [Indexed: 11/22/2022]
Abstract
Trytophan Hydroxylase Type I (TPH1), most abundantly expressed in the gastrointestinal tract, initiates the synthesis of serotonin by catalyzing hydroxylation of tryptophan in the presence of biopterin and oxygen. We have previously described three series of novel, periphery-specific TPH1 inhibitors that selectively deplete serotonin in the gastrointestinal tract. We have now determined co-crystal structures of TPH1 with three of these inhibitors at high resolution. Analysis of the structural data showed that each of the three inhibitors fills the tryptophan binding pocket of TPH1 without reaching into the binding site of the cofactor pterin, and induces major conformational changes of the enzyme. The enzyme-inhibitor complexes assume a compact conformation that is similar to the one in tryptophan complex. Kinetic analysis showed that all three inhibitors are competitive versus the substrate tryptophan, consistent with the structural data that the compounds occupy the tryptophan binding site. On the other hand, all three inhibitors appear to be uncompetitive versus the cofactor 6-methyltetrahydropterin, which is not only consistent with the structural data but also indicate that the hydroxylation reaction follows an ordered binding mechanism in which a productive complex is formed only if tryptophan binds only after pterin, similar to the kinetic mechanisms of tyrosine and phenylalanine hydroxylase.
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Affiliation(s)
- Giovanni Cianchetta
- Department of Medicinal Chemistry, Lexicon Pharmaceuticals, Inc., 350 Carter Rd., Princeton, New Jersey, USA
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228
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Chen GL, Novak MA, Meyer JS, Kelly BJ, Vallender EJ, Miller GM. TPH2 5'- and 3'-regulatory polymorphisms are differentially associated with HPA axis function and self-injurious behavior in rhesus monkeys. GENES, BRAIN, AND BEHAVIOR 2010; 9:335-47. [PMID: 20059554 PMCID: PMC2990963 DOI: 10.1111/j.1601-183x.2010.00564.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Tryptophan hydroxylase-2 (TPH2) synthesizes neuronal serotonin and is linked to numerous behavioral traits. We have previously characterized the functionality of polymorphisms (especially 2051A>C) in 3'-untranslated region (3'-UTR) of rhesus monkey TPH2 (rhTPH2). This study further assessed the functionality of additional polymorphisms (-1605T>C, -1491Tn, -1485(AT)n, -1454A>G, -1325In>Del and -363T>G) in rhTPH2 5'-flanking region (5'-FR), and evaluated the effects of rhTPH2 5' and 3' genotypes on central serotonin turnover, hypothalamic-pituitary-adrenal (HPA) axis function and self-injurious behavior (SIB) in 32 unrelated adult male monkeys of Indian origin. Haplotypes of the rhTPH2 5'-FR polymorphisms exert a significant, cell-dependent effect on reporter gene expression, primarily conferred by -1485(AT)n. The -1485(AT)n and 2051A>C polymorphisms interact to influence cerebrospinal fluid (CSF) 5-HIAA and plasma adrenocorticotropic hormone (ACTH) in the afternoon. While -1485(AT)n exerts significant main effects on the afternoon cortisol level and nocturnal HPA negative feedback, 2051A>C has significant main effects on the morning cortisol level and cortisol response to ACTH challenge, as well as marginally significant main effects on the daytime HPA negative feedback and self-biting rate. In addition, the genotype/allele frequency of the 5'-FR -1325Ins>Del differed significantly between the self-wounders and non-wounders, whereas 3'-UTR 2128S>L polymorphism differed significantly in genotype/allele frequency between the high- and low-frequency biters. This study shows the functionality of rhTPH2 5'-FR polymorphisms, and provides evidence for the differential association of rhTPH2 5'-FR and 3'-UTR polymorphisms with HPA axis function and SIB. Our findings shed light on the role of TPH2 gene variance in physiology and behavioral traits, and also contribute to the understanding of the pathophysiology and genetics of SIB.
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Affiliation(s)
- Guo-Lin Chen
- Harvard Medical School, New England Primate Research Center, Division of Neurochemistry, One Pine Hill Drive, Southborough, MA 01772–9102, USA
| | - Melinda A. Novak
- Harvard Medical School, New England Primate Research Center, Division of Neurochemistry, One Pine Hill Drive, Southborough, MA 01772–9102, USA
- Department of Psychology, University of Massachusetts at Amherst, Amherst, MA, USA
| | - Jerrold S. Meyer
- Department of Psychology, University of Massachusetts at Amherst, Amherst, MA, USA
| | - Brian J. Kelly
- Harvard Medical School, New England Primate Research Center, Division of Neurochemistry, One Pine Hill Drive, Southborough, MA 01772–9102, USA
| | - Eric J. Vallender
- Harvard Medical School, New England Primate Research Center, Division of Neurochemistry, One Pine Hill Drive, Southborough, MA 01772–9102, USA
| | - Gregory M. Miller
- Harvard Medical School, New England Primate Research Center, Division of Neurochemistry, One Pine Hill Drive, Southborough, MA 01772–9102, USA
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Bai CF, Liu JC, Zhao R, Cao W, Liu SB, Zhang XN, Guo HJ, Yang Q, Yi DH, Zhao MG. Role of 5-HT2B receptors in cardiomyocyte apoptosis in noradrenaline-induced cardiomyopathy in rats. Clin Exp Pharmacol Physiol 2010; 37:e145-51. [DOI: 10.1111/j.1440-1681.2010.05388.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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230
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Inoue H, Yamasue H, Tochigi M, Takei K, Suga M, Abe O, Yamada H, Rogers MA, Aoki S, Sasaki T, Kasai K. Effect of tryptophan hydroxylase-2 gene variants on amygdalar and hippocampal volumes. Brain Res 2010; 1331:51-7. [PMID: 20331984 DOI: 10.1016/j.brainres.2010.03.057] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2009] [Revised: 03/14/2010] [Accepted: 03/15/2010] [Indexed: 02/06/2023]
Abstract
Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the synthesis of serotonin (5-HT). Genetic variations in human TPH2, a newly identified isoform of TPH, have been shown to impact on enzymatic activity of TPH and to be associated with emotion-related personality traits and mood/anxiety disorders. Identification of an intermediate phenotype that bridges the relationship between genes and behavior may be of great importance in the further clarification of how hTPH2 contributes to emotional regulation. Previous studies have shown that a polymorphism in the upstream regulatory region of hTPH2 (SNP G-703T, rs4570625) correlates functional MRI response of the amygdala. In this study, we examined the effect of this genotype on amygdalar and hippocampal volumes in 208 mentally healthy individuals. To measure volumes of amygdala and hippocampus, gray matter regions of interest were outlined manually on three-dimensional MRI data obtained using a 1.5-T scanner. Additionally, personality traits were evaluated using the Temperament and Character Inventory (TCI). Those subjects with T allele carriers were associated with significantly smaller volumes in bilateral amygdala and hippocampus and higher reward dependence than those with G allele homozygotes. These results suggest that amygdalar and hippocampal volumes assessed using MRI may be a useful intermediate phenotype that will uncover the biological pathway linking 5-HT synthesis and emotional behaviors and affective disorders.
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Affiliation(s)
- Hideyuki Inoue
- Department of Neuropsychiatry, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
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231
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Oh WJ, Westmoreland JJ, Summers R, Condie BG. Cleft palate is caused by CNS dysfunction in Gad1 and Viaat knockout mice. PLoS One 2010; 5:e9758. [PMID: 20333300 PMCID: PMC2841638 DOI: 10.1371/journal.pone.0009758] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Accepted: 03/01/2010] [Indexed: 12/22/2022] Open
Abstract
Background Previous studies have shown that disruption of GABA signaling in mice via mutations in the Gad1, Gabrb3 or Viaat genes leads to the development of non-neural developmental defects such as cleft palate. Studies of the Gabrb3 and Gad1 mutant mice have suggested that GABA function could be required either in the central nervous system or in the palate itself for normal palatogenesis. Methodology/Principal Findings To further examine the role of GABA signaling in palatogenesis we used three independent experimental approaches to test whether Gad1 or Viaat function is required in the fetal CNS for normal palate development. We used oral explant cultures to demonstrate that the Gad1 and Viaat mutant palates were able to undergo palatogenesis in culture, suggesting that there is no defect in the palate tissue itself in these mice. In a second series of experiments we found that the GABAA receptor agonist muscimol could rescue the cleft palate phenotype in Gad1 and Viaat mutant embryos. This suggested that normal multimeric GABAA receptors in the CNS were necessary for normal palatogenesis. In addition, we showed that CNS-specific inactivation of Gad1 was sufficient to disrupt palate development. Conclusions/Significance Our results are consistent with a role for Gad1 and Viaat in the central nervous system for normal development of the palate. We suggest that the alterations in GABA signaling lead to non-neural defects such as cleft palate as a secondary effect due to alterations in or elimination of fetal movements.
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Affiliation(s)
- Won-Jong Oh
- Developmental Biology Group, Department of Genetics, University of Georgia, Athens, Georgia, United States of America
- Institute of Molecular Medicine, Medical College of Georgia, Augusta, Georgia, United States of America
| | - Joby J. Westmoreland
- Institute of Molecular Medicine, Medical College of Georgia, Augusta, Georgia, United States of America
| | - Ryan Summers
- Developmental Biology Group, Department of Genetics, University of Georgia, Athens, Georgia, United States of America
| | - Brian G. Condie
- Developmental Biology Group, Department of Genetics, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
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232
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Saetre P, Lundmark P, Wang A, Hansen T, Rasmussen HB, Djurovic S, Melle I, Andreassen OA, Werge T, Agartz I, Hall H, Terenius L, Jönsson EG. The tryptophan hydroxylase 1 (TPH1) gene, schizophrenia susceptibility, and suicidal behavior: a multi-centre case-control study and meta-analysis. Am J Med Genet B Neuropsychiatr Genet 2010; 153B:387-396. [PMID: 19526457 DOI: 10.1002/ajmg.b.30991] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Serotonin (5-hydroxytryptamin; 5-HT) alternations has since long been suspected in the pathophysiology of schizophrenia. Tryptophan hydroxylase (tryptophan 5-monooxygenase; TPH) is the rate-limiting enzyme in the biosynthesis of 5-HT, and sequence variation in intron 6 of the TPH1 gene has been associated with schizophrenia. The minor allele (A) of this polymorphism (A218C) is also more frequent in patients who have attempted suicide and individuals who died by suicide, than in healthy control individuals. In an attempt to replicate previous findings, five single nucleotide polymorphisms (SNPs) were genotyped in 837 Scandinavian schizophrenia patients and 1,473 controls. Three SNPs spanning intron 6 and 7, including the A218C and A779C polymorphisms, were associated with schizophrenia susceptibility (P = 0.019). However there were no differences in allele frequencies of these loci between affected individuals having attempted suicide at least once and patients with no history of suicide attempts (P = 0.84). A systematic literature review and meta-analysis support the A218C polymorphism as a susceptibility locus for schizophrenia (odds ratio 1.17, 95% confidence interval 1.07-1.29). Association studies on suicide attempts are however conflicting (heterogeneity index I(2) = 0.54) and do not support the A218C/A779C polymorphisms being a susceptibility locus for suicidal behavior among individuals diagnosed with a psychiatric disorder (OR = 0.96 [0.80-1.16]). We conclude that the TPH1 A218/A779 locus increases the susceptibility of schizophrenia in Caucasian and Asian populations. In addition, the data at hand suggest that the locus contributes to the liability of psychiatric disorders characterized by elevated suicidal rates, rather than affecting suicidal behavior of individuals suffering from a psychiatric disorder.
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Affiliation(s)
- Peter Saetre
- Department of Clinical Neuroscience, HUBIN Project, Karolinska Institutet and Hospital, Stockholm, Sweden
| | - Per Lundmark
- Department of Medical Sciences, Molecular Medicine, Uppsala University, Uppsala, Sweden
| | - August Wang
- Mental Health Center Amager, Copenhagen University Hospital, Copenhagen, Denmark
| | - Thomas Hansen
- Research Institute of Biological Psychiatry, Copenhagen University Hospital, Mental Health Centre Sct. Hans, Roskilde, Denmark.,Centre for Pharmacogenomics, University of Copenhagen, Copenhagen N, Denmark
| | - Henrik B Rasmussen
- Research Institute of Biological Psychiatry, Copenhagen University Hospital, Mental Health Centre Sct. Hans, Roskilde, Denmark
| | - Srdjan Djurovic
- Institute of Psychiatry, University of Oslo, Oslo, Norway.,Department of Medical Genetics, Ullevål University Hospital, Oslo, Norway.,Department of Psychiatry, Ullevål University Hospital, Oslo, Norway
| | - Ingrid Melle
- Institute of Psychiatry, University of Oslo, Oslo, Norway.,Department of Medical Genetics, Ullevål University Hospital, Oslo, Norway.,Department of Psychiatry, Ullevål University Hospital, Oslo, Norway
| | - Ole A Andreassen
- Institute of Psychiatry, University of Oslo, Oslo, Norway.,Department of Medical Genetics, Ullevål University Hospital, Oslo, Norway.,Department of Psychiatry, Ullevål University Hospital, Oslo, Norway
| | - Thomas Werge
- Research Institute of Biological Psychiatry, Copenhagen University Hospital, Mental Health Centre Sct. Hans, Roskilde, Denmark
| | - Ingrid Agartz
- Department of Clinical Neuroscience, HUBIN Project, Karolinska Institutet and Hospital, Stockholm, Sweden.,Institute of Psychiatry, University of Oslo, Oslo, Norway.,Department of Psychiatric Research, Diakonhjemmet Hospital, Oslo, Norway
| | - Håkan Hall
- Department of Clinical Neuroscience, HUBIN Project, Karolinska Institutet and Hospital, Stockholm, Sweden
| | - Lars Terenius
- Department of Clinical Neuroscience, HUBIN Project, Karolinska Institutet and Hospital, Stockholm, Sweden
| | - Erik G Jönsson
- Department of Clinical Neuroscience, HUBIN Project, Karolinska Institutet and Hospital, Stockholm, Sweden
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Chen GL, Novak MA, Meyer JS, Kelly BJ, Vallender EJ, Miller GM. The effect of rearing experience and TPH2 genotype on HPA axis function and aggression in rhesus monkeys: a retrospective analysis. Horm Behav 2010; 57:184-91. [PMID: 19900455 PMCID: PMC2815197 DOI: 10.1016/j.yhbeh.2009.10.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 10/28/2009] [Accepted: 10/29/2009] [Indexed: 01/14/2023]
Abstract
Gene-environment (GxE) interactions contribute to the development of many neuropsychiatric disorders. Tryptophan hydroxylase-2 (TPH2) synthesizes neuronal serotonin and is closely related to the hypothalamic-pituitary-adrenal (HPA) axis, while early life experience is a critical environmental factor programming the HPA axis response to stress. This retrospective study investigated GxE interaction at the TPH2 locus in rhesus monkeys. Twenty-eight adult, male rhesus monkeys of Indian origin, either mother-reared or peer-reared as infants, were involved in this study. These monkeys have been previously genotyped for the functional A2051C polymorphism in rhTPH2, and had been physiologically and behaviorally characterized. rhTPH2 A2051C exerted a significant main effect (CC>AA&AC) on the cerebrospinal fluid (CSF) level of 5-hydroxyindole-3-acetic acid (5-HIAA; F((1,14))=6.42, p=0.024), plasma cortisol level in the morning (F((1,18))=14.63, p=0.002) and cortisol response to ACTH challenge (F((1,17))=6.87, p=0.018), while the rearing experience showed a significant main effect (PR>MR) on CSF CRH (F((1,20))=11.66, p=0.003) and cage shaking behavior (F((1,27))=4.45, p=0.045). The effects of rhTPH2 A2051C on the afternoon cortisol level, plasma ACTH level, dexamethasone suppression of urinary cortisol excretion, and aggression were dependent upon the rearing experience. These results were not confounded by the functional C77G polymorphism in the mu-opioid receptor (MOR). The present study supports the hypothesis that rearing experience and rhTPH2 A2051C interact to influence central 5-HT metabolism, HPA axis function, and aggressive behaviors. Our findings strengthen the involvement of G x E interactions at the loci of serotonergic genes and the utility of the nonhuman primate to model G x E interactions in the development of human neuropsychiatric diseases.
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Affiliation(s)
- Guo-Lin Chen
- Harvard Medical School, New England Primate Research Center, Division of Neurochemistry, One Pine Hill Drive, Southborough, MA 01772, USA
| | - Melinda A. Novak
- Harvard Medical School, New England Primate Research Center, Division of Neurochemistry, One Pine Hill Drive, Southborough, MA 01772, USA
- Department of Psychology, University of Massachusetts at Amherst, Amherst, MA 01003, USA
| | - Jerrold S. Meyer
- Department of Psychology, University of Massachusetts at Amherst, Amherst, MA 01003, USA
| | - Brian J. Kelly
- Harvard Medical School, New England Primate Research Center, Division of Neurochemistry, One Pine Hill Drive, Southborough, MA 01772, USA
- Department of Psychology, University of Massachusetts at Amherst, Amherst, MA 01003, USA
| | - Eric J. Vallender
- Harvard Medical School, New England Primate Research Center, Division of Neurochemistry, One Pine Hill Drive, Southborough, MA 01772, USA
| | - Gregory M. Miller
- Harvard Medical School, New England Primate Research Center, Division of Neurochemistry, One Pine Hill Drive, Southborough, MA 01772, USA
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234
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Hasegawa H, Nakamura K. Tryptophan Hydroxylase and Serotonin Synthesis Regulation. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2010. [DOI: 10.1016/s1569-7339(10)70078-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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235
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Scheuch K, Höltje M, Budde H, Lautenschlager M, Heinz A, Ahnert-Hilger G, Priller J. Lithium modulates tryptophan hydroxylase 2 gene expression and serotonin release in primary cultures of serotonergic raphe neurons. Brain Res 2010; 1307:14-21. [DOI: 10.1016/j.brainres.2009.10.027] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Revised: 10/06/2009] [Accepted: 10/12/2009] [Indexed: 12/13/2022]
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236
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Rufer ES, Hacker TA, Flentke GR, Drake VJ, Brody MJ, Lough J, Smith SM. Altered cardiac function and ventricular septal defect in avian embryos exposed to low-dose trichloroethylene. Toxicol Sci 2009; 113:444-52. [PMID: 19910388 DOI: 10.1093/toxsci/kfp269] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Trichloroethylene (TCE) is the most frequently reported organic groundwater contaminant in the United States. It is controversial whether gestational TCE exposure causes congenital heart defects. The basis for TCE's proposed cardiac teratogenicity is not well understood. We previously showed that chick embryos exposed to 8 ppb TCE during cardiac morphogenesis have reduced cardiac output and increased mortality. To further investigate TCE's cardioteratogenic potential, we exposed in ovo chick embryos to TCE and evaluated the heart thereafter. Significant mortality was observed following TCE exposures of 8-400 ppb during a narrow developmental period (Hamburger-Hamilton [HH] stages 15-20, embryo day ED2.3-3.5) that is characterized by myocardial expansion, secondary heart looping, and endocardial cushion formation. Of the embryos that died, most did so between ED5.5 and ED6.5. Echocardiography of embryos at ED5.5 found that TCE-exposed hearts displayed significant functional and morphological heterogeneity affecting heart rate, left ventricular mass, and wall thickness. Individual embryos were identified with cardiac hypertrophy as well as with hypoplasia. Chick embryos exposed to 8 ppb TCE at HH17 that survived to hatch exhibited a high incidence (38%, p < 0.01, n = 16) of muscular ventricular septal defects (VSDs) as detected by echocardiography and confirmed by gross dissection; no VSDs were found in controls (n = 14). The TCE-induced VSDs may be secondary to functional impairments that alter cardiac hemodynamics and subsequent ventricular foramen closure, an interpretation consistent with recent demonstrations that TCE impairs calcium handling in cardiomyocytes. These data demonstrate that TCE is a cardiac teratogen for chick.
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Affiliation(s)
- Echoleah S Rufer
- Molecular and Environmental Toxicology Center, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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237
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Pai VP, Marshall AM, Hernandez LL, Buckley AR, Horseman ND. Altered serotonin physiology in human breast cancers favors paradoxical growth and cell survival. Breast Cancer Res 2009; 11:R81. [PMID: 19903352 PMCID: PMC2815543 DOI: 10.1186/bcr2448] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 10/25/2009] [Accepted: 11/10/2009] [Indexed: 02/07/2023] Open
Abstract
Introduction The breast microenvironment can either retard or accelerate the events associated with progression of latent cancers. However, the actions of local physiological mediators in the context of breast cancers are poorly understood. Serotonin (5-HT) is a critical local regulator of epithelial homeostasis in the breast and other organs. Herein, we report complex alterations in the intrinsic mammary gland serotonin system of human breast cancers. Methods Serotonin biosynthetic capacity was analyzed in human breast tumor tissue microarrays using immunohistochemistry for tryptophan hydroxylase 1 (TPH1). Serotonin receptors (5-HT1-7) were analyzed in human breast tumors using the Oncomine database. Serotonin receptor expression, signal transduction, and 5-HT effects on breast cancer cell phenotype were compared in non-transformed and transformed human breast cells. Results In the context of the normal mammary gland, 5-HT acts as a physiological regulator of lactation and involution, in part by favoring growth arrest and cell death. This tightly regulated 5-HT system is subverted in multiple ways in human breast cancers. Specifically, TPH1 expression undergoes a non-linear change during progression, with increased expression during malignant progression. Correspondingly, the tightly regulated pattern of 5-HT receptors becomes dysregulated in human breast cancer cells, resulting in both ectopic expression of some isoforms and suppression of others. The receptor expression change is accompanied by altered downstream signaling of 5-HT receptors in human breast cancer cells, resulting in resistance to 5-HT-induced apoptosis, and stimulated proliferation. Conclusions Our data constitutes the first report of direct involvement of 5-HT in human breast cancer. Increased 5-HT biosynthetic capacity accompanied by multiple changes in 5-HT receptor expression and signaling favor malignant progression of human breast cancer cells (for example, stimulated proliferation, inappropriate cell survival). This occurs through uncoupling of serotonin from the homeostatic regulatory mechanisms of the normal mammary epithelium. The findings open a new avenue for identification of diagnostic and prognostic markers, and valuable new therapeutic targets for managing breast cancer.
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Affiliation(s)
- Vaibhav P Pai
- Department of Molecular and Cellular Physiology, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH, 45267-0576, USA.
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238
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Weber T, Böhm G, Hermann E, Schütz G, Schönig K, Bartsch D. Inducible gene manipulations in serotonergic neurons. Front Mol Neurosci 2009; 2:24. [PMID: 19936315 PMCID: PMC2779094 DOI: 10.3389/neuro.02.024.2009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 10/14/2009] [Indexed: 01/30/2023] Open
Abstract
An impairment of the serotonergic (5-HT) system has been implicated in the etiology of many neuropsychiatric disorders. Despite the considerable genetic evidence, the exact molecular and pathophysiological mechanisms underlying this dysfunction remain largely unknown. To address the lack of instruments for the molecular dissection of gene function in serotonergic neurons we have developed a new mouse transgenic tool that allows inducible Cre-mediated recombination of genes selectively in 5-HT neurons of all raphe nuclei. In this transgenic mouse line, the tamoxifen-inducible CreERT2 recombinase is expressed under the regulatory control of the mouse tryptophan hydroxylase 2 (Tph2) gene locus (177 kb). Tamoxifen treatment efficiently induced recombination selectively in serotonergic neurons with minimal background activity in vehicle-treated mice. These genetic manipulations can be initiated at any desired time during embryonic development, neonatal stage or adulthood. To illustrate the versatility of this new tool, we show that Brainbow-1.0L(TPH2-CreERT2) mice display highly efficient recombination in serotonergic neurons with individual 5-HT neurons labeling with multiple distinct fluorescent colors. This labeling is well suited for visualization and tracing of serotonergic neurons and their network architecture. Finally, the applicability of TPH2-CreERT2 for loxP-flanked candidate gene manipulation is evidenced by our successful knockout induction of the ubiquitously expressed glucocorticoid-receptor exclusively in 5-HT neurons of adult mice. The TPH2-CreERT2 line will allow detailed analysis of gene function in both developing and adult serotonergic neurons.
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Affiliation(s)
- Tillmann Weber
- Department of Molecular Biology, Central Institute of Mental Health, Heidelberg University Mannheim, Germany
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239
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Tph2 gene variants modulate response control processes in adult ADHD patients and healthy individuals. Mol Psychiatry 2009; 14:1032-9. [PMID: 18427560 DOI: 10.1038/mp.2008.39] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Although therapeutic interventions in attention-deficit/hyperactivity disorder (ADHD) still focus on the dopaminergic system, recent studies indicate a serotonergic dysfunction in this disease as well. In that respect, several variants of the tryptophan hydroxylase gene (TPH2), which codes for the rate-limiting enzyme in the biosynthesis of serotonin (5-HT), have been associated with ADHD. The rs4570625 G-allele polymorphisms of the TPH2 gene have already been related to altered reactivity of the brain during perception tasks with emotional stimuli in healthy adults. Here we investigated the influence of the ADHD related risk alleles for rs4570625 and for rs11178997 on prefrontal brain function during cognitive response control in large samples of adult ADHD patients (n=124) and healthy controls (n=84). Response control was elicited with a Go-NoGo task (continuous performance test; CPT) performed during recording of an ongoing EEG. From the resulting event-related potentials in the Go- and NoGo conditions of the CPT, the NoGo-anteriorization (NGA) has been calculated as a valid neurophysiological parameter for prefrontal brain function. In the current study, ADHD risk alleles of both polymorphisms were found to be associated with a reduction in the NGA in both healthy controls and ADHD patients. These findings are in line with the notion that genetic variations associated with altered serotonergic neurotransmission are also associated with the function of the prefrontal cortex during response inhibition. This mechanism might also be relevant in the pathophysiology of ADHD.
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240
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Ghia JE, Li N, Wang H, Collins M, Deng Y, El-Sharkawy RT, Côté F, Mallet J, Khan WI. Serotonin has a key role in pathogenesis of experimental colitis. Gastroenterology 2009; 137:1649-60. [PMID: 19706294 DOI: 10.1053/j.gastro.2009.08.041] [Citation(s) in RCA: 291] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Revised: 07/03/2009] [Accepted: 08/06/2009] [Indexed: 02/08/2023]
Abstract
BACKGROUND & AIMS Mucosal changes in inflammatory bowel disease are characterized by ulcerative lesions accompanied by a prominent infiltrate of immune cells as well as alteration in serotonin (5-hydroxytryptamine [5-HT])-producing enterochromaffin cells. We investigated the role of 5-HT in colonic inflammation in mice. METHODS Colitis was induced with dextran sulfate sodium or dinitrobenzene sulfonic acid in tryptophan hydroxylase 1-deficient (TPH1(-/-)) mice, which have markedly reduced 5-HT in the gastrointestinal tract, and in mice given the 5-HT synthesis inhibitor parachlorophenylalanine. RESULTS Delayed onset, decreased severity of clinical disease, and significantly lower macroscopic and histologic damage scores were observed in TPH1(-/-) mice, compared with wild-type mice, and in mice given parachlorophenylalanine after induction of colitis by dextran sulfate sodium. This was associated with down-regulation of macrophage infiltration and production of proinflammatory cytokines. 5-HT stimulated production of proinflammatory cytokines from macrophages collected from the peritoneal cavity of wild-type mice; this process was inhibited by a nuclear factor kappaB inhibitor, indicating a critical role for nuclear factor kappaB signaling in 5-HT-mediated activation of immune cells. Restoration of 5-HT levels in TPH1(-/-) mice by the 5-HT precursor 5-hydroxytryptophan increased the severity of DSS-induced colitis. We also observed significant reduction in severity of colitis in TPH1(-/-) mice after induction of dinitrobenzene sulfonic acid-induced colitis. CONCLUSIONS 5-HT is involved in the pathogenesis of inflammation in experimental colitis. These findings provide insight into the mechanisms of gastrointestinal inflammation and could lead to new therapeutic strategies for inflammatory disorders.
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Affiliation(s)
- Jean-Eric Ghia
- Farncombe Family Digestive Health Research Institute, Department of Pathology & Molecular Medicine, McMaster University, Ontario, Canada
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Hioki H, Nakamura H, Ma YF, Konno M, Hayakawa T, Nakamura KC, Fujiyama F, Kaneko T. Vesicular glutamate transporter 3-expressing nonserotonergic projection neurons constitute a subregion in the rat midbrain raphe nuclei. J Comp Neurol 2009; 518:668-86. [DOI: 10.1002/cne.22237] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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242
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Fligny C, Hatia S, Amireault P, Mallet J, Côté F. Mammalian prenatal development: the influence of maternally derived molecules. Bioessays 2009; 31:935-43. [DOI: 10.1002/bies.200800217] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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243
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McKinney JA, Turel B, Winge I, Knappskog PM, Haavik J. Functional properties of missense variants of human tryptophan hydroxylase 2. Hum Mutat 2009; 30:787-94. [PMID: 19319927 DOI: 10.1002/humu.20956] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Tryptophan hydroxylase 2 (TPH2) catalyzes the rate-limiting step in serotonin biosynthesis in the nervous system. Several variants of human TPH2 have been reported to be associated with a spectrum of neuropsychiatric disorders such as unipolar major depression, bipolar disorder, suicidality, and attention-deficit/hyperactivity disorder (ADHD). We used three different expression systems: rabbit reticulocyte lysate, Escherichia coli, and human embryonic kidney cells, to identify functional effects of all human TPH2 missense variants reported to date. The properties of mutants affecting the regulatory domain, that is, p.Leu36Val, p.Leu36Pro, p.Ser41Tyr, and p.Arg55Cys, were indistinguishable from the wild-type (WT). Moderate loss-of-function effects were observed for mutants in the catalytic and oligomerization domains, that is, p.Pro206Ser, p.Ala328Val, p.Arg441His, and p.Asp479Glu, which were manifested via stability and solubility effects, whereas p.Arg303Trp had severely reduced solubility and was completely inactive. All variants were tested as substrates for protein kinase A and were found to have similar phosphorylation stoichiometries. A standardized assay protocol as described here for activity and solubility screening should also be useful for determining properties of other TPH2 variants that will be discovered in the future.
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244
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Growth retardation and altered autonomic control in mice lacking brain serotonin. Proc Natl Acad Sci U S A 2009; 106:10332-7. [PMID: 19520831 DOI: 10.1073/pnas.0810793106] [Citation(s) in RCA: 259] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Serotonin synthesis in mammals is initiated by 2 distinct tryptophan hydroxylases (TPH), TPH1 and TPH2. By genetically ablating TPH2, we created mice (Tph2(-/-)) that lack serotonin in the central nervous system. Surprisingly, these mice can be born and survive until adulthood. However, depletion of serotonin signaling in the brain leads to growth retardation and 50% lethality in the first 4 weeks of postnatal life. Telemetric monitoring revealed more extended daytime sleep, suppressed respiration, altered body temperature control, and decreased blood pressure (BP) and heart rate (HR) during nighttime in Tph2(-/-) mice. Moreover, Tph2(-/-) females, despite being fertile and producing milk, exhibit impaired maternal care leading to poor survival of their pups. These data confirm that the majority of central serotonin is generated by TPH2. TPH2-derived serotonin is involved in the regulation of behavior and autonomic pathways but is not essential for adult life.
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Affiliation(s)
- Michael D Gershon
- Department of Pathology and Cell Biology, Columbia University, P & S, 630 West 168th Street, New York, NY 10032, USA.
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246
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Role of serotonin in gastrointestinal motility and irritable bowel syndrome. Clin Chim Acta 2009; 403:47-55. [DOI: 10.1016/j.cca.2009.01.028] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Revised: 01/17/2009] [Accepted: 01/19/2009] [Indexed: 12/18/2022]
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Genetic deletion of MAO-A promotes serotonin-dependent ventricular hypertrophy by pressure overload. J Mol Cell Cardiol 2009; 46:587-95. [DOI: 10.1016/j.yjmcc.2008.12.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Accepted: 12/15/2008] [Indexed: 11/17/2022]
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Gutknecht L, Kriegebaum C, Waider J, Schmitt A, Lesch KP. Spatio-temporal expression of tryptophan hydroxylase isoforms in murine and human brain: convergent data from Tph2 knockout mice. Eur Neuropsychopharmacol 2009; 19:266-82. [PMID: 19181488 DOI: 10.1016/j.euroneuro.2008.12.005] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 12/05/2008] [Accepted: 12/16/2008] [Indexed: 01/17/2023]
Abstract
Dysregulation of tryptophan hydroxylase (TPH)-dependent serotonin (5-HT) synthesis, has been implicated in various neuropsychiatric disorders, although the differential expression pattern of the two isoforms is controversial. Here, we report a comprehensive spatio-temporal isoform-specific analysis of TPH1 and TPH2 expression during pre- and postnatal development of mouse brain and in adult human brain. TPH2 expression was consistently detected in the raphe nuclei, as well as in fibers in the deep pineal gland and in small intestine. Although TPH1 expression was found in these peripheral tissues, no significant TPH1 expression was detected in the brain, neither during murine development, nor in mouse and human adult brain. In support of TPH2 specificity in brain 5-HT synthesis, raphe neurons of Tph2 knockout mice were completely devoid of 5-HT, with no compensatory activation of Tph1 expression. In conclusion, our findings indicate that brain 5-HT synthesis across the lifespan is exclusively maintained by TPH2.
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Affiliation(s)
- Lise Gutknecht
- Molecular and Clinical Psychobiology, Department of Psychiatry, Psychosomatics, and Psychotherapy, University of Wuerzburg, Fuechsleinstrasse 15, 97080 Wuerzburg, Germany.
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249
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Kanai M, Funakoshi H, Takahashi H, Hayakawa T, Mizuno S, Matsumoto K, Nakamura T. Tryptophan 2,3-dioxygenase is a key modulator of physiological neurogenesis and anxiety-related behavior in mice. Mol Brain 2009; 2:8. [PMID: 19323847 PMCID: PMC2673217 DOI: 10.1186/1756-6606-2-8] [Citation(s) in RCA: 211] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Accepted: 03/27/2009] [Indexed: 04/19/2023] Open
Abstract
Although nutrients, including amino acids and their metabolites such as serotonin (5-HT), are strong modulators of anxiety-related behavior, the metabolic pathway(s) responsible for this physiological modulation is not fully understood. Regarding tryptophan (Trp), the initial rate-limiting enzymes for the kynurenine pathway of tryptophan metabolism are tryptophan 2,3-dioxygenase (TDO) and indoleamine 2,3-dioxygenase (IDO). Here, we generated mice deficient for tdo (Tdo-/-). Compared with wild-type littermates, Tdo-/- mice showed increased plasma levels of Trp and its metabolites 5-hydroxyindoleacetic acid (5-HIAA) and kynurenine, as well as increased levels of Trp, 5-HT and 5-HIAA in the hippocampus and midbrain. These mice also showed anxiolytic modulation in the elevated plus maze and open field tests, and increased adult neurogenesis, as evidenced by double staining of BrdU and neural progenitor/neuronal markers. These findings demonstrate a direct molecular link between Trp metabolism and neurogenesis and anxiety-related behavior under physiological conditions.
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Affiliation(s)
- Masaaki Kanai
- Division of Molecular Regenerative Medicine, Department of Biochemistry and Molecular Biology, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan.
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250
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Fernandes PACM, Bothorel B, Clesse D, Monteiro AWA, Calgari C, Raison S, Simonneaux V, Markus RP. Local corticosterone infusion enhances nocturnal pineal melatonin production in vivo. J Neuroendocrinol 2009; 21:90-7. [PMID: 19076264 DOI: 10.1111/j.1365-2826.2008.01817.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Melatonin, an important marker of the endogenous rhythmicity in mammals, also plays a role in the body defence against pathogens and injuries. In vitro experiments have shown that either pro- or anti-inflammatory agents, acting directly in the organ, are able to change noradrenaline-induced pineal indoleamine production. Whereas corticosterone potentiates melatonin production, incubation of the gland with tumour necrosis factor-alpha decreases pineal hormonal production. In the present study, we show that nocturnal melatonin production measured by intra-pineal microdialysis is enhanced in pineals perfused with corticosterone at concentrations similar to those measured in inflamed animals. In vitro experiments suggest that this enhancement may be due to an increase in the activity of the two enzymes that convert serotonin to N-acetylserotonin (NAS) and NAS to melatonin. The present results support the hypothesis that the pineal gland is a sensor of inflammation mediators and that it plays a central role in the control of the inflammatory response.
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Affiliation(s)
- P A C M Fernandes
- Laboratório de Cronofarmacologia, Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
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