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Kao WY, Hsiang CY, Ho SC, Ho TY, Lee KT. Novel serotonin-boosting effect of incense smoke from Kynam agarwood in mice: The involvement of multiple neuroactive pathways. JOURNAL OF ETHNOPHARMACOLOGY 2021; 275:114069. [PMID: 33794334 DOI: 10.1016/j.jep.2021.114069] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 03/22/2021] [Indexed: 06/12/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Stress is a state of feeling that inhibits one from responding properly in the face of a threat. Agarwood smoke has been used in traditional medicine as a sedative anti-anxious, and anti-restless therapy. Its scent emitted from heat induces people to enter a stable state; however, the underlying molecular effect is still unclear. AIM OF THE STUDY This study analyzed novel biological events and gene expression signatures induced by agarwood incense smoke in mice. MATERIALS AND METHODS Incense smoke was produced by heating at 150 °C for 30 min in a headspace autosampler oven. We treated mice with exposure to incense smoke from Kynam agarwood for 45 min/day for 7 consecutive days. After a 7-day inhalation period, the potent agarwood smoke affected-indicators in serum were measured, and the RNA profiles of the mouse brains were analyzed by microarray to elucidate the biological events induced by agarwood incense smoke. RESULTS Chemical profile analysis showed that the major component in the incense smoke of Kynam was 2-(2-phenylethyl) chromone (26.82%). Incense smoke from Kynam induced mice to enter a stable state and increased the levels of serotonin in sera. The emotion-related pathways, including dopaminergic synapse, serotonergic synapse, GABAergic synapse, long-term depression and neuroactive ligand-receptor interaction, were significantly affected by incense smoke. Moreover, the expression of Crhr2 and Chrnd genes, involved with neuroactive ligand-receptor interaction pathway, was upregulated by incense smoke. CONCLUSIONS By a newly-established incense smoke exposure system, we first identified that anti-anxious and anti-depressant effects of agarwood incense smoke were likely associated with the increase of serotonin levels and multiple neuroactive pathways in mice.
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Affiliation(s)
- Wen-Yi Kao
- Department of Biochemical Science and Technology, National Taiwan University, Taipei, 10617, Taiwan; Development Center for Biotechnology, Taipei, 11571, Taiwan
| | - Chien-Yun Hsiang
- Department of Microbiology and Immunology, China Medical University, Taichung, 40402, Taiwan
| | - Shih-Ching Ho
- Development Center for Biotechnology, Taipei, 11571, Taiwan
| | - Tin-Yun Ho
- Graduate Institute of Chinese Medicine, China Medical University, Taichung, 40402, Taiwan.
| | - Kung-Ta Lee
- Department of Biochemical Science and Technology, National Taiwan University, Taipei, 10617, Taiwan.
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Badamasi IM, Lye MS, Ibrahim N, Stanslas J. Genetic endophenotypes for insomnia of major depressive disorder and treatment-induced insomnia. J Neural Transm (Vienna) 2019; 126:711-722. [PMID: 31111219 DOI: 10.1007/s00702-019-02014-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 05/11/2019] [Indexed: 12/12/2022]
Abstract
Major depressive disorder (MDD) is primarily hinged on the presence of either low mood and/or anhedonia to previously pleasurable events for a minimum of 2 weeks. Other clinical features that characterize MDD include disturbances in sleep, appetite, concentration and thoughts. The combination of any/both of the primary MDD symptoms as well as any four of the other clinical features has been referred to as MDD. The challenge for replicating gene association findings with phenotypes of MDD as well as its treatment outcome is putatively due to stratification of MDD patients. Likelihood for replication of gene association findings is hypothesized with specificity in symptoms profile (homogenous clusters of symptom/individual symptoms) evaluated. The current review elucidates the genetic factors that have been associated with insomnia symptom of MDD phenotype, insomnia symptom as a constellation of neuro-vegetative cluster of MDD symptom, insomnia symptom of MDD as an individual entity and insomnia feature of treatment outcome. Homozygous CC genotype of 3111T/C, GSK3B-AT/TT genotype of rs33458 and haplotype of TPH1 218A/C were associated with insomnia symptom of MDD. Insomnia symptom of MDD was not resolved in patients with the A/A genotype of HTR2A-rs6311 when treated with SSRI. Homozygous short (SS) genotype-HTTLPR, GG genotype of HTR2A-rs6311 and CC genotype of HTR2A-rs6313 were associated with AD treatment-induced insomnia, while val/met genotype of BDNF-rs6265 and the TT genotype of GSK-3beta-rs5443 reduced it. Dearth of association studies may remain the bane for the identification of robust genetic endophenotypes in line with findings for genotypes of HTR2A-rs6311.
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Affiliation(s)
- Ibrahim Mohammed Badamasi
- Pharmacotherapeutics Unit, Department of Medicine, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Munn Sann Lye
- Department of Community Health, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Normala Ibrahim
- Department of Psychiatry, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Johnson Stanslas
- Pharmacotherapeutics Unit, Department of Medicine, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia.
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Zhang J, Han X, Si S, Zhang S. The Interaction of TPH1 A779C Polymorphism and Maternal Authoritarianism on Creative Potential. Front Psychol 2018; 9:2106. [PMID: 30450068 PMCID: PMC6224424 DOI: 10.3389/fpsyg.2018.02106] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Accepted: 10/12/2018] [Indexed: 11/13/2022] Open
Abstract
Exploring the possible mechanisms through which gene may interact with environment to influence creativity has been one of the leading issues in creativity research. In a sample of four hundred and twenty-one Chinese undergraduate students, the present study investigated for the first time the interaction of TPH1 A779C polymorphism and maternal parenting styles on creative potential. The results showed that there was a significant interaction of TPH1 A779C polymorphism and maternal authoritarianism on creative potential. Moreover, the analysis of regions of significance (Ros) provided supporting evidences for both the diathesis-stress model (flexibility) and the differential susceptibility model (originality). These findings extend our understanding concerning the mechanisms by which gene and environment may act in coordination to contribute to creativity.
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Affiliation(s)
- Jinghuan Zhang
- Department of Psychology, Shandong Normal University, Jinan, China
| | - Xiao Han
- Department of Psychology, Shandong Normal University, Jinan, China
| | - Si Si
- Department of Psychology, Shandong Normal University, Jinan, China
| | - Shun Zhang
- Department of Psychology, Shandong Normal University, Jinan, China
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Morandini L, Ramallo MR, Moreira RG, Höcht C, Somoza GM, Silva A, Pandolfi M. Serotonergic outcome, stress and sexual steroid hormones, and growth in a South American cichlid fish fed with an L-tryptophan enriched diet. Gen Comp Endocrinol 2015; 223:27-37. [PMID: 26449161 DOI: 10.1016/j.ygcen.2015.10.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Revised: 09/11/2015] [Accepted: 10/04/2015] [Indexed: 11/24/2022]
Abstract
Reared animals for edible or ornamental purposes are frequently exposed to high aggression and stressful situations. These factors generally arise from conspecifics in densely breeding conditions. In vertebrates, serotonin (5-HT) has been postulated as a key neuromodulator and neurotransmitter involved in aggression and stress. The essential amino acid L-tryptophan (trp) is crucial for the synthesis of 5-HT, and so, leaves a gateway for indirectly augmenting brain 5-HT levels by means of a trp-enriched diet. The cichlid fish Cichlasoma dimerus, locally known as chanchita, is an autochthonous, potentially ornamental species and a fruitful laboratory model which behavior and reproduction has been studied over the last 15years. It presents complex social hierarchies, and great asymmetries between subordinate and dominant animals in respect to aggression, stress, and reproductive chance. The first aim of this work was to perform a morphological description of chanchita's brain serotonergic system, in both males and females. Then, we evaluated the effects of a trp-supplemented diet, given during 4weeks, on brain serotonergic activity, stress and sexual steroid hormones, and growth in isolated specimens. Results showed that chanchita's brain serotonergic system is composed of several populations of neurons located in three main areas: pretectum, hypothalamus and raphe, with no clear differences between males and females at a morphological level. Animals fed with trp-enriched diets exhibited higher forebrain serotonergic activity and a significant reduction in their relative cortisol levels, with no effects on sexual steroid plasma levels or growth parameters. Thus, this study points to food trp enrichment as a "neurodietary'' method for elevating brain serotonergic activity and decreasing stress, without affecting growth or sex steroid hormone levels.
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Affiliation(s)
- Leonel Morandini
- Laboratorio de Neuroendocrinología y Comportamiento, DBBE e IBBEA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Intendente Güirlades 2160, C1428EHA Ciudad Autónoma de Buenos Aires, Argentina
| | - Martín Roberto Ramallo
- Laboratorio de Neuroendocrinología y Comportamiento, DBBE e IBBEA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Intendente Güirlades 2160, C1428EHA Ciudad Autónoma de Buenos Aires, Argentina
| | - Renata Guimarães Moreira
- Departamento de Fisiologia, Instituto de Biociências-USP, Rua do Matão, travessa 14, n.321, sala 220 CidadeUniversitária, São Paulo, Brazil
| | - Christian Höcht
- Departamento de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina
| | - Gustavo Manuel Somoza
- IIB-INTECH (CONICET-UNSAM), Av. Intendente Marino km 8.2 (B 7130IWA) Chascomús, Buenos Aires, Argentina
| | - Ana Silva
- Unidad Bases Neurales de la Conducta, Instituto de Investigaciones Biológicas Clemente Estable, Ministerio de Educación y Cultura, Avda. Italia 3318, 11600 Montevideo, Uruguay; Laboratorio de Neurociencias, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay
| | - Matías Pandolfi
- Laboratorio de Neuroendocrinología y Comportamiento, DBBE e IBBEA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Intendente Güirlades 2160, C1428EHA Ciudad Autónoma de Buenos Aires, Argentina.
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Myung W, Song J, Lim SW, Won HH, Kim S, Lee Y, Kang HS, Lee H, Kim JW, Carroll BJ, Kim DK. Genetic association study of individual symptoms in depression. Psychiatry Res 2012; 198:400-6. [PMID: 22429480 DOI: 10.1016/j.psychres.2011.12.037] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 12/19/2011] [Accepted: 12/25/2011] [Indexed: 12/12/2022]
Abstract
The heritability of some individual depressive symptoms has been well established. However, the causal genes related to individual depressive symptoms and genetic effects on the courses of individual depressive symptoms are still unclear. We examined these issues in 241 Korean patients who met the DSM-IV-TR criteria for major depression. Patients entered a 12-week clinical trial with antidepressants. A total of 1399 single-nucleotide polymorphisms (SNPs) of 79 candidate genes were assessed. The rs557762 and the TT haplotype in the 11th haplotype block of the GRIA3 gene were associated with feelings of guilt in females. The GGCCGGGC haplotype in the first haplotype block of TPH1 was significantly associated with middle insomnia. The ACAG haplotype in the 13th haplotype block of the GRIK2 gene was associated with somatic anxiety. Moreover, the effect of the rs557762 on guilt significantly varied across times. Our results indicate that there are associations between particular gene polymorphisms and some individual depressive symptoms. These results could contribute to understanding the biological mechanisms of depression.
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Affiliation(s)
- Woojae Myung
- Department of Psychiatry, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Irwon-dong, Kangnam-gu, Seoul 135-710, Republic of Korea
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Rahman S, Khan IA, Thomas P. Tryptophan hydroxylase: a target for neuroendocrine disruption. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2011; 14:473-494. [PMID: 21790322 DOI: 10.1080/10937404.2011.578563] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Tryptophan hydroxylase (TPH), the rate-limiting enzyme in serotonin (5-HT) synthesis, performs an essential role in the maintenance of serotonergic functions in the central nervous system (CNS), including regulation of the neuroendocrine system controlling reproduction. The results of recent studies in a teleost model of neuroendocrine disruption, Atlantic croaker, indicated that hypothalamic TPH is a major site of interference of hypothalamic-pituitary-gonadal function by environmental stressors. The effects of exposure to two different types of environmental stressors, low dissolved oxygen (hypoxia) and a polychlorinated biphenyl mixture (Aroclor 1254), on the stimulatory brain serotonergic system controlling reproductive neuroendocrine function in Atlantic croaker are reviewed. Exposure to both stressors produced decreases in TPH activity, which were accompanied by a fall in hypothalamic 5-HT and gonadotropin-releasing hormone (GnRH I) content in the preoptic-anterior hypothalamic area and were associated with reduction in luteinizing hormone (LH) secretion and gonadal development. Pharmacological restoration of hypothalamic 5-HT levels after exposure to both stressors also restored neuroendocrine and reproductive functions, indicating that the serotonergic system is an important site for hypoxia- and Aroclor 1254-induced inhibition of reproductive neuroendocrine functions. The mechanisms underlying downregulation of TPH activity by these stressors remain unclear but may involve alterations in hypothalamic antioxidant status. In support of this hypothesis, treatment with an antioxidant, vitamin E, was found to reverse the inhibitory effects of Aroclor 1254 on TPH activity. The results suggest that TPH is a major target for neuroendocrine disruption by diverse environmental stressors.
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Affiliation(s)
- Saydur Rahman
- Marine Science Institute, University of Texas at Austin, Port Aransas, Texas 78373, USA
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Molecular cloning, characterization and expression of two tryptophan hydroxylase (TPH-1 and TPH-2) genes in the hypothalamus of Atlantic croaker: down-regulation after chronic exposure to hypoxia. Neuroscience 2008; 158:751-65. [PMID: 19015006 DOI: 10.1016/j.neuroscience.2008.10.029] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Revised: 09/02/2008] [Accepted: 10/10/2008] [Indexed: 11/20/2022]
Abstract
Recently we discovered that hypoxia causes marked impairment of reproductive neuroendocrine function in Atlantic croaker, a marine teleost, which is due to a decline in hypothalamic serotonergic activity. As a first step in understanding the molecular responses of the hypothalamic serotonergic system to hypoxia, we cloned and characterized the genes for the enzymes regulating the rate-limiting step in serotonin biosynthesis, tryptophan hydroxylase (TPH-1 and TPH-2) in the croaker brain. The full-length croaker TPH-1 and TPH-2 cDNAs contain open reading frames encoding proteins with 479 and 487 amino acids, respectively, which are highly homologous to the TPH-1 (76-93%) and TPH-2 (64-92%) proteins of other vertebrates. Croaker TPH-1 and TPH-2 mRNA expression was detected throughout the brain but was greatest in the hypothalamic region. Both Northern blot analysis and real-time PCR showed that TPH-1 (transcript size approximately 2.1 kb) and TPH-2 ( approximately 1.9 kb) mRNA levels were significantly decreased in the hypothalami of croaker exposed for 2 weeks to hypoxic conditions compared with those in fish exposed to normoxic conditions. Immunohistochemistry of hypothalamic neurons with TPH antibodies showed reduced expression of TPHs in hypoxia-exposed fish compared with normoxic fish. Western blot analysis confirmed that hypoxia caused a marked decline in hypothalamic TPH protein levels, which was associated with decreases in hypothalamic TPH enzyme activity and 5-hydroxytryptophan levels. These results suggest that TPH is a major site of hypoxia-induced down-regulation of serotonergic function in croaker brains. Moreover, they provide the first evidence that hypoxia decreases the expression of TPH transcripts in vertebrate brains.
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Stress Upregulates TPH1 but not TPH2 mRNA in the Rat Dorsal Raphe Nucleus: Identification of Two TPH2 mRNA Splice Variants. Cell Mol Neurobiol 2008; 28:331-42. [DOI: 10.1007/s10571-007-9259-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Accepted: 12/15/2007] [Indexed: 12/18/2022]
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Tenner K, Walther D, Bader M. Influence of human tryptophan hydroxylase 2 N- and C-terminus on enzymatic activity and oligomerization. J Neurochem 2007; 102:1887-1894. [PMID: 17539919 DOI: 10.1111/j.1471-4159.2007.04664.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Tryptophan hydroxylase (TPH) catalyses the first and rate limiting step in the biosynthesis of the neurotransmitter serotonin. There are two TPH isoenzymes in humans, encoded by two different genes: TPH1 and the recently described TPH2. We have expressed both human enzymes and various deletion mutants of TPH2 (DeltaN44, DeltaC17, DeltaC19, DeltaC51) in COS7 cells. TPH1 and 2 displayed different kinetic properties with a lower K(m) value of TPH1. Removal of 44 amino acids from the N-terminus of TPH2 resulted in a 3-4-fold increased V(max), which indicates a strong inhibitory function of this part on the enzymes activity. TPH1 and 2 were able to form homooligomers and also heterooligomers with each other. The different deletion mutants (DeltaC17, DeltaC19 and DeltaC51), which lack the putative C-terminal leucine zipper tetramerization domain, existed as monomeric enzymes. While short deletions (DeltaC17 and DeltaC19) hardly changed V(max) values, the DeltaC51 mutant lost 99% of TPH activity. These data identify a region between the C-terminal oligomerization domain and the catalytic domain, which is indispensable for TPH2 activity.
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Affiliation(s)
- K Tenner
- Max Delbrück Center for Molecular Medicine, Berlin, GermanyMax Planck Institute for Molecular Genetics, Department for Human Genetics, Berlin, Germany
| | - D Walther
- Max Delbrück Center for Molecular Medicine, Berlin, GermanyMax Planck Institute for Molecular Genetics, Department for Human Genetics, Berlin, Germany
| | - M Bader
- Max Delbrück Center for Molecular Medicine, Berlin, GermanyMax Planck Institute for Molecular Genetics, Department for Human Genetics, Berlin, Germany
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Patel PD, Pontrello C, Burke S. Robust and tissue-specific expression of TPH2 versus TPH1 in rat raphe and pineal gland. Biol Psychiatry 2004; 55:428-33. [PMID: 14960297 DOI: 10.1016/j.biopsych.2003.09.002] [Citation(s) in RCA: 163] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2003] [Revised: 08/29/2003] [Accepted: 09/03/2003] [Indexed: 11/25/2022]
Abstract
BACKGROUND Regulation of raphe serotonergic cells is fundamental to the prevailing hypothesis of major depression pathophysiology. Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in serotonin biosynthesis, but brainstem TPH mRNA expression has been difficult to measure and study. Recently, a novel paralog of TPH, TPH2 (or neuronal TPH), was described, but its anatomic expression is unknown. METHODS In situ hybridization histochemical survey was conducted across Sprague-Dawley rat brain for TPH1 and TPH2 mRNA. Semiquantitative techniques were used to estimate relative mRNA levels in individual cells. RESULTS Almost exclusively, TPH2 mRNA is expressed in raphe, in a pattern overlapping the histologically defined raphe nuclei. In sharp contrast, TPH1 (the previously known TPH) is expressed predominantly in pineal gland. There is no appreciable overlap in the expression of these paralogs. The level of TPH2 mRNA expression in individual raphe cells is approximately 2.5-fold greater than the level of TPH1 expression in pinealocytes. CONCLUSIONS TPH2 mRNA has an anatomic expression pattern consistent with brainstem raphe nuclei and is likely to be the gene giving rise to the majority of TPH activity in these cells. The robust expression of TPH2 in brainstem should facilitate studies on the transcriptional regulation of raphe serotonin biosynthesis.
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Affiliation(s)
- Paresh D Patel
- Mental Health Research Institute, University of Michigan Medical Center, C560 MSRB II, 1150 W. Medical Center Drive, Ann Arbor, MI 48109-0669, USA
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Affiliation(s)
- M C Boadle-Biber
- Department of Physiology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond 23298
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Stone DM, Hanson GR, Gibb JW. In vitro reactivation of rat cortical tryptophan hydroxylase following in vivo inactivation by methylenedioxymethamphetamine. J Neurochem 1989; 53:572-81. [PMID: 2568404 DOI: 10.1111/j.1471-4159.1989.tb07372.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The activity of tryptophan hydroxylase (EC 1.14.16.4) from rat brain was significantly decreased 1 h following a single systemic injection of 3,4-methylenedioxymethamphetamine (MDMA) when assessed ex vivo by radioenzymatic assay or in vivo by the quantitation of 5-hydroxytryptophan accumulation following central L-aromatic amino acid decarboxylase inhibition. Recovery of enzymatic activity in vivo, which occurred within 24 h of low-dose MDMA treatment, appeared not to involve synthesis of new enzyme protein, because the return of enzymatic activity was not prevented by prior cycloheximide. Acutely MDMA-depressed cortical tryptophan hydroxylase activity could be completely restored in vitro by a prolonged (20-24 h) anaerobic incubation in the presence of dithiothreitol and Fe2+ at 25 degrees C; partial reconstitution occurred when 2-mercapto-ethanol was substituted for dithiothreitol. Cortical tryptophan hydroxylase acutely inactivated by methamphetamine or p-chloroamphetamine could be similarly reactivated. MDMA-inactivated cortical tryptophan hydroxylase derived from rats killed later than 3 days after drug treatment could not be significantly reactivated under the conditions described above, indicating the development of irreversible enzymatic damage. Kinetic analysis of enzyme reactivation revealed an approximate doubling of enzyme Vmax with no change in enzyme affinity for either substrate, tryptophan, or pterin cofactor. These studies suggest that MDMA and its congeners inactivate central tryptophan hydroxylase by inducing oxidation of key enzyme sulfhydryl groups. The reactivation capacity of drug-inactivated enzyme at various times after MDMA treatment may provide a means of assessing the development of MDMA-induced neurotoxicity.
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Affiliation(s)
- D M Stone
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City 84112
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Nilsson GE, Tottmar O. Effects of biogenic aldehydes and aldehyde dehydrogenase inhibitors on rat brain tryptophan hydroxylase activity in vitro. Brain Res 1987; 409:374-9. [PMID: 2438010 DOI: 10.1016/0006-8993(87)90726-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The effect of indole-3-acetaldehyde, 5-hydroxyindole-3-acetaldehyde, disulfiram, diethyldithiocarbamate, coprine, and 1-amino-cyclopropanol on tryptophan hydroxylase activity was studied in vitro using high performance liquid chromatography with electro-chemical detection. With the analytical method developed, 5-hydroxytryptophan, serotonin, and 5-hydroxyindole-3-acetic acid could be measured simultaneously. Indole-3-acetaldehyde (12-1200 microM) was found to cause a 6-33% inhibition of the enzyme. Dependent upon the nature of the sulfhydryl- or reducing-agent (dithiotreitol, glutathione, or ascorbate) present in the incubates, the degree of inhibition by disulfiram varied, probably due to the formation of various mixed disulfides. Also the presence of diethyldithiocarbamate (160-1600 microM) was found to inhibit tryptophan hydroxylase (28-91%), while 5-hydroxyindole-3-acetaldehyde, coprine, or 1-aminocyclopropanol appeared to have no effect on the enzyme activity.
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