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Hung LY, Margolis KG. Autism spectrum disorders and the gastrointestinal tract: insights into mechanisms and clinical relevance. Nat Rev Gastroenterol Hepatol 2024; 21:142-163. [PMID: 38114585 DOI: 10.1038/s41575-023-00857-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/11/2023] [Indexed: 12/21/2023]
Abstract
Autism spectrum disorders (ASDs) are recognized as central neurodevelopmental disorders diagnosed by impairments in social interactions, communication and repetitive behaviours. The recognition of ASD as a central nervous system (CNS)-mediated neurobehavioural disorder has led most of the research in ASD to be focused on the CNS. However, gastrointestinal function is also likely to be affected owing to the neural mechanistic nature of ASD and the nervous system in the gastrointestinal tract (enteric nervous system). Thus, it is unsurprising that gastrointestinal disorders, particularly constipation, diarrhoea and abdominal pain, are highly comorbid in individuals with ASD. Gastrointestinal problems have also been repeatedly associated with increased severity of the core symptoms diagnostic of ASD and other centrally mediated comorbid conditions, including psychiatric issues, irritability, rigid-compulsive behaviours and aggression. Despite the high prevalence of gastrointestinal dysfunction in ASD and its associated behavioural comorbidities, the specific links between these two conditions have not been clearly delineated, and current data linking ASD to gastrointestinal dysfunction have not been extensively reviewed. This Review outlines the established and emerging clinical and preclinical evidence that emphasizes the gut as a novel mechanistic and potential therapeutic target for individuals with ASD.
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Affiliation(s)
- Lin Y Hung
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY, USA
| | - Kara Gross Margolis
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY, USA.
- Department of Cell Biology, NYU Grossman School of Medicine and Langone Medical Center, New York, NY, USA.
- Department of Pediatrics, NYU Grossman School of Medicine and Langone Medical Center, New York, NY, USA.
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2
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What is the mechanism of loudness hyperacusis in autism? Med Hypotheses 2022. [DOI: 10.1016/j.mehy.2021.110759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Stilley SE, Blakely RD. Rare Opportunities for Insights Into Serotonergic Contributions to Brain and Bowel Disorders: Studies of the SERT Ala56 Mouse. Front Cell Neurosci 2021; 15:677563. [PMID: 34149362 PMCID: PMC8210832 DOI: 10.3389/fncel.2021.677563] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 04/27/2021] [Indexed: 12/12/2022] Open
Abstract
Altered structure, expression, and regulation of the presynaptic serotonin (5-HT) transporter (SERT) have been associated with multiple neurobehavioral disorders, including mood disorders, obsessive-compulsive disorder (OCD), and autism spectrum disorder (ASD). Opportunities to investigate mechanistic links supporting these associations were spurred with the identification of multiple, rare human SERT coding variants in a study that established a male-specific linkage of ASD to a linkage marker on chromosome 17 which encompassed the location of the SERT gene (SLC6A4). We have explored the most common of these variants, SERT Ala56, in vitro and in vivo. Results support a tonic elevation of 5-HT transport activity in transfected cells and human lymphoblasts by the variant in vitro that leads to an increased 5-HT clearance rate in vivo when studied in the SERT Ala56 mouse model, along with altered sensitivity to SERT regulatory signaling pathways. Importantly, hyperserotonemia, or an elevated whole blood 5-HT, level, was found in SERT Ala56 mice, reproducing a well-replicated trait observed in a significant fraction of ASD subjects. Additionally, we found multiple biochemical, physiological, and behavioral alterations in the SERT Ala56 mice that can be analogized to those observed in ASD and its medical comorbidities. The similarity of the functional impact of the SERT Ala56 variant to the consequences of p38α MAPK activation, ascribed to the induction of a biased conformation of the transporter toward an outward-facing conformation, has resulted in successful efforts to restore normal behavioral and bowel function via pharmacological and genetic p38α MAPK targeting. Moreover, the ability of the inflammatory cytokine IL-1β to enhance SERT activity via a p38α MAPK-dependent pathway suggests that the SERT Ala56 conformation mimics that of a chronic inflammatory state, supporting findings in ASD of elevated inflammatory cytokine levels. In this report, we review studies of the SERT Ala56 variant, discussing opportunities for continued insight into how chronically altered synaptic 5-HT homeostasis can drive reversible, functional perturbations in 5-HT sensitive pathways in the brain and periphery, and how targeting the SERT regulome, particularly through activating pathways such as those involving IL-1β/p38α MAPK, may be of benefit for neurobehavioral disorders, including ASD.
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Affiliation(s)
- Samantha E. Stilley
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, United States
| | - Randy D. Blakely
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, United States
- Brain Institute, Florida Atlantic University, Jupiter, FL, United States
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Meinke C, Quinlan MA, Paffenroth KC, Harrison FE, Fenollar-Ferrer C, Katamish RM, Stillman I, Ramamoorthy S, Blakely RD. Serotonin Transporter Ala276 Mouse: Novel Model to Assess the Neurochemical and Behavioral Impact of Thr276 Phosphorylation In Vivo. Neurochem Res 2021; 47:37-60. [PMID: 33830406 DOI: 10.1007/s11064-021-03299-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 02/21/2021] [Accepted: 03/17/2021] [Indexed: 11/30/2022]
Abstract
The serotonin (5-HT) transporter (SERT) is a key regulator of 5-HT signaling and is a major target for antidepressants and psychostimulants. Human SERT coding variants have been identified in subjects with obsessive-compulsive disorder (OCD) and autism spectrum disorder (ASD) that impact transporter phosphorylation, cell surface trafficking and/or conformational dynamics. Prior to an initial description of a novel mouse line expressing the non-phosphorylatable SERT substitution Thr276Ala, we review efforts made to elucidate the structure and conformational dynamics of SERT with a focus on research implicating phosphorylation at Thr276 as a determinant of SERT conformational dynamics. Using the high-resolution structure of human SERT in inward- and outward-open conformations, we explore the conformation dependence of SERT Thr276 exposure, with results suggesting that phosphorylation is likely restricted to an inward-open conformation, consistent with prior biochemical studies. Assessment of genotypes from SERT/Ala276 heterozygous matings revealed a deviation from Mendelian expectations, with reduced numbers of Ala276 offspring, though no genotype differences were seen in growth or physical appearance. Similarly, no genotype differences were evident in midbrain or hippocampal 5-HT levels, midbrain and hippocampal SERT mRNA or midbrain protein levels, nor in midbrain synaptosomal 5-HT uptake kinetics. Behaviorally, SERT Ala276 homozygotes appeared normal in measures of anxiety and antidepressant-sensitive stress coping behavior. However, these mice displayed sex-dependent alterations in repetitive and social interactions, consistent with circuit-dependent requirements for Thr276 phosphorylation underlying these behaviors. Our findings indicate the utility of SERT Ala276 mice in evaluation of developmental, functional and behavioral consequences of regulatory SERT phosphorylation in vivo.
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Affiliation(s)
- Carina Meinke
- International Max Planck Research School for Brain and Behavior, Max Planck Florida Institute for Neuroscience, Jupiter, FL, USA.,Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Meagan A Quinlan
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA.,Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, USA
| | | | - Fiona E Harrison
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Cristina Fenollar-Ferrer
- Laboratories of Molecular Genetics and Molecular Biology, National Institute On Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Rania M Katamish
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Isabel Stillman
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | | | - Randy D Blakely
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA. .,Florida Atlantic University Brain Institute, Rm 109, MC-17, 5353 Parkside Dr, Jupiter, FL, 35348, USA.
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Serotonin 5-HT 1B receptor-mediated behavior and binding in mice with the overactive and dysregulated serotonin transporter Ala56 variant. Psychopharmacology (Berl) 2021; 238:1111-1120. [PMID: 33511450 PMCID: PMC8728944 DOI: 10.1007/s00213-020-05758-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 12/28/2020] [Indexed: 10/22/2022]
Abstract
RATIONALE Elevated whole-blood serotonin (5-HT) is a robust biomarker in ~ 30% of patients with autism spectrum disorders, in which repetitive behavior is a core symptom. Furthermore, elevated whole-blood 5-HT has also been described in patients with pediatric obsessive-compulsive disorder. The 5-HT1B receptor is associated with repetitive behaviors seen in both disorders. Chronic blockade of serotonin transporter (SERT) reduces 5-HT1B receptor levels in the orbitofrontal cortex (OFC) and attenuates the sensorimotor deficits and hyperactivity seen with the 5-HT1B agonist RU24969. We hypothesized that enhanced SERT function would increase 5-HT1B receptor levels in OFC and enhance sensorimotor deficits and hyperactivity induced by RU24969. OBJECTIVES We examined the impact of the SERT Ala56 mutation, which leads to enhanced SERT function, on 5-HT1B receptor binding and 5-HT1B-mediated sensorimotor deficits. METHODS Specific binding to 5-HT1B receptors was measured in OFC and striatum of naïve SERT Ala56 or wild-type mice. The impact of the 5-HT1A/1B receptor agonist RU24969 on prepulse inhibition (PPI) of startle, hyperactivity, and expression of cFos was examined. RESULTS While enhanced SERT function increased 5-HT1B receptor levels in OFC of Ala56 mice, RU24969-induced PPI deficits and hyperlocomotion were not different between genotypes. Baseline levels of cFos expression were not different between groups. RU24969 increased cFos expression in OFC of wild-types and decreased cFos in the striatum. CONCLUSIONS While reducing 5-HT1B receptors may attenuate sensorimotor gating deficits, increased 5-HT1B levels in SERT Ala56 mice do not necessarily exacerbate these deficits, potentially due to compensations during neural circuit development in this model system.
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Quinlan MA, Robson MJ, Ye R, Rose KL, Schey KL, Blakely RD. Ex vivo Quantitative Proteomic Analysis of Serotonin Transporter Interactome: Network Impact of the SERT Ala56 Coding Variant. Front Mol Neurosci 2020; 13:89. [PMID: 32581705 PMCID: PMC7295033 DOI: 10.3389/fnmol.2020.00089] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 04/28/2020] [Indexed: 12/15/2022] Open
Abstract
Altered serotonin (5-HT) signaling is associated with multiple brain disorders, including major depressive disorder (MDD), obsessive-compulsive disorder (OCD), and autism spectrum disorder (ASD). The presynaptic, high-affinity 5-HT transporter (SERT) tightly regulates 5-HT clearance after release from serotonergic neurons in the brain and enteric nervous systems, among other sites. Accumulating evidence suggests that SERT is dynamically regulated in distinct activity states as a result of environmental and intracellular stimuli, with regulation perturbed by disease-associated coding variants. Our lab identified a rare, hypermorphic SERT coding substitution, Gly56Ala, in subjects with ASD, finding that the Ala56 variant stabilizes a high-affinity outward-facing conformation (SERT∗) that leads to elevated 5-HT uptake in vitro and in vivo. Hyperactive SERT Ala56 appears to preclude further activity enhancements by p38α mitogen-activated protein kinase (MAPK) and can be normalized by pharmacological p38α MAPK inhibition, consistent with SERT Ala56 mimicking, constitutively, a high-activity conformation entered into transiently by p38α MAPK activation. We hypothesize that changes in SERT-interacting proteins (SIPs) support the shift of SERT into the SERT∗ state which may be captured by comparing the composition of SERT Ala56 protein complexes with those of wildtype (WT) SERT, defining specific interactions through comparisons of protein complexes recovered using preparations from SERT–/– (knockout; KO) mice. Using quantitative proteomic-based approaches, we identify a total of 459 SIPs, that demonstrate both SERT specificity and sensitivity to the Gly56Ala substitution, with a striking bias being a loss of SIP interactions with SERT Ala56 compared to WT SERT. Among this group are previously validated SIPs, such as flotillin-1 (FLOT1) and protein phosphatase 2A (PP2A), whose functions are believed to contribute to SERT microdomain localization and regulation. Interestingly, our studies nominate a number of novel SIPs implicated in ASD, including fragile X mental retardation 1 protein (FMR1) and SH3 and multiple ankyrin repeat domains protein 3 (SHANK3), of potential relevance to long-standing evidence of serotonergic contributions to ASD. Further investigation of these SIPs, and the broader networks they engage, may afford a greater understanding of ASD as well as other brain and peripheral disorders associated with perturbed 5-HT signaling.
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Affiliation(s)
- Meagan A Quinlan
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States.,Department of Pharmacology, Vanderbilt University, Nashville, TN, United States.,Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, United States
| | - Matthew J Robson
- Division of Pharmaceutical Sciences, James L. Winkle College of Pharmacy, University of Cincinnati, Cincinnati, OH, United States
| | - Ran Ye
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Kristie L Rose
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Kevin L Schey
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Randy D Blakely
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States.,Brain Institute, Florida Atlantic University, Jupiter, FL, United States
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Quinlan MA, Krout D, Katamish RM, Robson MJ, Nettesheim C, Gresch PJ, Mash DC, Henry LK, Blakely RD. Human Serotonin Transporter Coding Variation Establishes Conformational Bias with Functional Consequences. ACS Chem Neurosci 2019; 10:3249-3260. [PMID: 30668912 DOI: 10.1021/acschemneuro.8b00689] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The antidepressant-sensitive serotonin (5-HT) transporter (SERT) dictates rapid, high-affinity clearance of the neurotransmitter in both the brain and periphery. In a study of families with multiple individuals diagnosed with autism spectrum disorder (ASD), we previously identified several, rare, missense coding variants that impart elevated 5-HT transport activity, relative to wild-type SERT, upon heterologous expression as well as in ASD subject lymphoblasts. The most common of these variants, SERT Ala56, located in the transporter's cytosolic N-terminus, has been found to confer in transgenic mice hyperserotonemia, an ASD-associated biochemical trait, an elevated brain 5-HT clearance rate, and ASD-aligned behavioral changes. Hyperfunction of SERT Ala56 has been ascribed to a change in 5-HT KM, though the physical basis of this change has yet to be elucidated. Through assessments of fluorescence resonance energy transfer (FRET) between cytosolic N- and C-termini, sensitivity to methanethiosulfonates, and capacity for N-terminal tryptic digestion, we obtain evidence for mutation-induced conformational changes that support an open-outward 5-HT binding conformation in vitro and in vivo. Aspects of these findings were also evident with another naturally occurring C-terminal SERT coding variant identified in our ASD study, Asn605. We conclude that biased conformations of surface resident transporters that can impact transporter function and regulation are an unappreciated consequence of heritable and disease-associated SERT coding variation.
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Affiliation(s)
- Meagan A. Quinlan
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Danielle Krout
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58202, United States
| | | | - Matthew J. Robson
- Division of Pharmaceutical Sciences, University of Cincinnati, Cincinnati, Ohio 45267, United States
| | | | | | - Deborah C. Mash
- Dr. Kiran Patel College of Allopathic Medicine, Nova Southeastern University, Davie, Florida 33314, United States
| | - L. Keith Henry
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58202, United States
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Garbarino VR, Gilman TL, Daws LC, Gould GG. Extreme enhancement or depletion of serotonin transporter function and serotonin availability in autism spectrum disorder. Pharmacol Res 2019; 140:85-99. [PMID: 30009933 PMCID: PMC6345621 DOI: 10.1016/j.phrs.2018.07.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 06/22/2018] [Accepted: 07/12/2018] [Indexed: 12/15/2022]
Abstract
A variety of human and animal studies support the hypothesis that serotonin (5-hydroxytryptamine or 5-HT) system dysfunction is a contributing factor to the development of autism in some patients. However, many questions remain about how developmental manipulation of various components that influence 5-HT signaling (5-HT synthesis, transport, metabolism) persistently impair social behaviors. This review will summarize key aspects of central 5-HT function important for normal brain development, and review evidence implicating perinatal disruptions in 5-HT signaling in the pathophysiology of autism spectrum disorder. We discuss the importance, and relative dearth, of studies that explore the possible correlation to autism in the interactions between important intrinsic and extrinsic factors that may disrupt 5-HT homeostasis during development. In particular, we focus on exposure to 5-HT transport altering mechanisms such as selective serotonin-reuptake inhibitors or genetic polymorphisms in primary or auxiliary transporters of 5-HT, and how they relate to neurological stores of serotonin and its precursors. A deeper understanding of the many mechanisms by which 5-HT signaling can be disrupted, alone and in concert, may contribute to an improved understanding of the etiologies and heterogeneous nature of this disorder. We postulate that extreme bidirectional perturbations of these factors during development likely compound or synergize to facilitate enduring neurochemical changes resulting in insufficient or excessive 5-HT signaling, that could underlie the persistent behavioral characteristics of autism spectrum disorder.
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Affiliation(s)
- Valentina R Garbarino
- Department of Cellular and Integrative Physiology, United States; The Sam and Ann Barshop Institute for Longevity and Aging Studies, United States.
| | - T Lee Gilman
- Department of Cellular and Integrative Physiology, United States; Addiction Research, Treatment & Training Center of Excellence, United States.
| | - Lynette C Daws
- Department of Cellular and Integrative Physiology, United States; Addiction Research, Treatment & Training Center of Excellence, United States; Department of Pharmacology, United States.
| | - Georgianna G Gould
- Department of Cellular and Integrative Physiology, United States; Center for Biomedical Neuroscience, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
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Montgomery AK, Shuffrey LC, Guter SJ, Anderson GM, Jacob S, Mosconi MW, Sweeney JA, Turner JB, Sutcliffe JS, Cook EH, Veenstra-VanderWeele J. Maternal Serotonin Levels Are Associated With Cognitive Ability and Core Symptoms in Autism Spectrum Disorder. J Am Acad Child Adolesc Psychiatry 2018; 57:867-875. [PMID: 30392628 PMCID: PMC6531860 DOI: 10.1016/j.jaac.2018.06.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 05/28/2018] [Accepted: 06/20/2018] [Indexed: 12/12/2022]
Abstract
OBJECTIVE The serotonin (5-hydroxytryptamine [HT]) system has long been implicated in autism spectrum disorder (ASD). Whole-blood 5-HT level (WB5-HT) is a stable, heritable biomarker that is elevated in more than 25% of children with ASD. Recent findings indicate that the maternal 5-HT system may influence embryonic neurodevelopment, but maternal WB5-HT has not been examined in relation to ASD phenotypes. METHOD WB5-HT levels were obtained from 181 individuals (3-27 years of age) diagnosed with ASD, 99 of their fathers, and 119 of their mothers. Standardized assessments were used to evaluate cognitive, behavioral, and language phenotypes. RESULTS Exploratory regression analyses found relationships between maternal WB5-HT and nonverbal IQ (NVIQ), Autism Diagnostic Interview-Revised (ADI-R) Nonverbal Communication Algorithm scores, and overall adaptive function on the Vineland Adaptive Behavior Scales-II. Latent class analysis identified a three-class structure in the assessment data, describing children with low, intermediate, and high severity across measures of behavior, cognition, and adaptive function. Mean maternal WB5-HT differed across classes, with the lowest maternal WB5-HT levels seen in the highest-severity group (Welch F2,46.048 = 17.394, p < .001). Paternal and proband WB5-HT did not differ between classes. CONCLUSION Maternal WB5-HT is associated with neurodevelopmental outcomes in offspring with ASD. Prospective, longitudinal studies will be needed to better understand the relationship between the function of the maternal serotonin system during pregnancy and brain development. Further studies in animal models may be able to reveal the mechanisms underlying these findings.
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Affiliation(s)
- Alicia K. Montgomery
- Columbia University Medical Center, New York, NY, and the New York State Psychiatric Institute, New York, NY; Center for Autism and the Developing Brain, New York-Presbyterian Hospital, White Plains, NY
| | - Lauren C. Shuffrey
- New York State Psychiatric Institute, New York, NY, and the Center for Autism and the Developing Brain, New York-Presbyterian Hospital, White Plains, NY. They are also with the Sackler Institute for Developmental Psychobiology; Columbia University Medical Center, New York, NY
| | - Stephen J. Guter
- Institute for Juvenile Research at the University of Illinois at Chicago, IL
| | | | | | - Matthew W. Mosconi
- Kansas Center for Autism Research and Training, Overland Park. He is also with the Clinical Child Psychology Program and Schiefelbusch Institute for Life Span Studies at the University of Kansas, Lawrence
| | | | - J. Blake Turner
- Columbia University Medical Center, New York, NY, and the New York State Psychiatric Institute, New York, NY
| | | | - Edwin H. Cook
- Institute for Juvenile Research at the University of Illinois at Chicago, IL
| | - Jeremy Veenstra-VanderWeele
- New York State Psychiatric Institute, New York, NY, and the Center for Autism and the Developing Brain, New York-Presbyterian Hospital, White Plains, NY. They are also with the Sackler Institute for Developmental Psychobiology; Columbia University Medical Center, New York, NY.
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p38α MAPK signaling drives pharmacologically reversible brain and gastrointestinal phenotypes in the SERT Ala56 mouse. Proc Natl Acad Sci U S A 2018; 115:E10245-E10254. [PMID: 30297392 PMCID: PMC6205438 DOI: 10.1073/pnas.1809137115] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Autism spectrum disorder (ASD) is a common neurobehavioral disorder with limited treatment options. Activation of p38 MAPK signaling networks has been identified in ASD, and p38 MAPK signaling elevates serotonin (5-HT) transporter (SERT) activity, effects mimicked by multiple, hyperfunctional SERT coding variants identified in ASD subjects. Mice expressing the most common of these variants (SERT Ala56) exhibit hyperserotonemia, a biomarker observed in ASD subjects, as well as p38 MAPK-dependent SERT hyperphosphorylation, elevated hippocampal 5-HT clearance, hypersensitivity of CNS 5-HT1A and 5-HT2A/2C receptors, and behavioral and gastrointestinal perturbations reminiscent of ASD. As the α-isoform of p38 MAPK drives SERT activation, we tested the hypothesis that CNS-penetrant, α-isoform-specific p38 MAPK inhibitors might normalize SERT Ala56 phenotypes. Strikingly, 1-week treatment of adult SERT Ala56 mice with MW150, a selective p38α MAPK inhibitor, normalized hippocampal 5-HT clearance, CNS 5-HT1A and 5-HT2A/2C receptor sensitivities, social interactions, and colonic motility. Conditional elimination of p38α MAPK in 5-HT neurons of SERT Ala56 mice restored 5-HT1A and 5-HT2A/2C receptor sensitivities as well as social interactions, mirroring effects of MW150. Our findings support ongoing p38α MAPK activity as an important determinant of the physiological and behavioral perturbations of SERT Ala56 mice and, more broadly, supports consideration of p38α MAPK inhibition as a potential treatment for core and comorbid phenotypes present in ASD subjects.
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Ellegood J, Yee Y, Kerr TM, Muller CL, Blakely RD, Henkelman RM, Veenstra-VanderWeele J, Lerch JP. Analysis of neuroanatomical differences in mice with genetically modified serotonin transporters assessed by structural magnetic resonance imaging. Mol Autism 2018; 9:24. [PMID: 29651330 PMCID: PMC5894125 DOI: 10.1186/s13229-018-0210-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 03/21/2018] [Indexed: 02/03/2023] Open
Abstract
Background The serotonin (5-HT) system has long been implicated in autism spectrum disorder (ASD) as indicated by elevated whole blood and platelet 5-HT, altered platelet and brain receptor and transporter binding, and genetic linkage and association findings. Based upon work in genetically modified mice, 5-HT is known to influence several aspects of brain development, but systematic neuroimaging studies have not previously been reported. In particular, the 5-HT transporter (serotonin transporter, SERT; 5-HTT) gene, Slc6a4, has been extensively studied. Methods Using a 7-T MRI and deformation-based morphometry, we assessed neuroanatomical differences in an Slc6a4 knockout mouse on a C57BL/6 genetic background, along with an Slc6a4 Ala56 knockin mouse on two different genetic backgrounds (129S and C57BL/6). Results Individually (same sex, same background, same genotype), the only differences found were in the female Slc6a4 knockout mouse; all the others had no significant differences. However, an analysis of variance across the whole study sample revealed a significant effect of Slc6a4 on the amygdala, thalamus, dorsal raphe nucleus, and lateral and frontal cortices. Conclusions This work shows that an increase or decrease in SERT function has a significant effect on the neuroanatomy in 5-HT relevant regions, particularly the raphe nuclei. Notably, the Slc6a4 Ala56 knockin alone appears to have an insignificant, but suggestive, effect compared to the KO, which is consistent with Slc6a4 function. Despite the small number of 5-HT neurons and their localization to the brainstem, it is clear that 5-HT plays an important role in neuroanatomical organization. Electronic supplementary material The online version of this article (10.1186/s13229-018-0210-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jacob Ellegood
- 1Mouse Imaging Centre (MICe), Hospital for Sick Children, 25 Orde Street, Toronto, Ontario M5T 3H7 Canada
| | - Yohan Yee
- 1Mouse Imaging Centre (MICe), Hospital for Sick Children, 25 Orde Street, Toronto, Ontario M5T 3H7 Canada.,4Department of Medical Biophysics, University of Toronto, Toronto, ON M5S Canada
| | - Travis M Kerr
- 3Department of Psychiatry, Vanderbilt University, Nashville, TN 37235 USA
| | | | - Randy D Blakely
- 2Department of Pharmacology, Vanderbilt University, Nashville, TN 37235 USA.,3Department of Psychiatry, Vanderbilt University, Nashville, TN 37235 USA.,5Department of Biomedical Science and Brain Institute, Florida Atlantic University, Jupiter, FL 33431 USA
| | - R Mark Henkelman
- 1Mouse Imaging Centre (MICe), Hospital for Sick Children, 25 Orde Street, Toronto, Ontario M5T 3H7 Canada.,4Department of Medical Biophysics, University of Toronto, Toronto, ON M5S Canada
| | - Jeremy Veenstra-VanderWeele
- 2Department of Pharmacology, Vanderbilt University, Nashville, TN 37235 USA.,6Department of Psychiatry, Columbia University, New York, NY 10027 USA
| | - Jason P Lerch
- 1Mouse Imaging Centre (MICe), Hospital for Sick Children, 25 Orde Street, Toronto, Ontario M5T 3H7 Canada.,4Department of Medical Biophysics, University of Toronto, Toronto, ON M5S Canada
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12
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Green J, Garg S. Annual Research Review: The state of autism intervention science: progress, target psychological and biological mechanisms and future prospects. J Child Psychol Psychiatry 2018; 59:424-443. [PMID: 29574740 DOI: 10.1111/jcpp.12892] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/18/2018] [Indexed: 12/20/2022]
Abstract
BACKGROUND There has been recent systematic review of key evidence in psychosocial intervention in autism but little review of biological treatments. METHODS We analyse the current literature from the perspective of intervention and mechanism targets across social and biological development. RESULTS The overall quality of trials evidence in autism intervention remains relatively low, despite some recent progress. Many treatments in common use have little or no evidence base. This is very concerning in such an important disorder. A variety of psychosocial interventions can show effect to improve some short-term effects on children's immediate dyadic social interactions, for instance with caregivers. But showing true effectiveness in this developmental disorder requires generalisation of such effects into wider social contexts, on autism symptoms and in long-term progress in development. Only a few interventions so far have begun to show this. A number of early phase interventions on biological targets have shown real promise, but none has yet progressed to larger scale effectiveness trials on behavioural or symptom outcomes. CONCLUSIONS There has been enough progress in psychosocial intervention research now to be able to begin to identify some evidence-based practice in autism treatment. To consolidate and improve outcomes, the next phase of intervention research needs improved trial design, and an iterative approach building on success. It may also include the testing of potential synergies between promising biological and psychosocial interventions.
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Affiliation(s)
- Jonathan Green
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.,Manchester Academic Health Science Centre, Manchester, UK.,Manchester University NHS Foundation Trust, Manchester, UK.,Greater Manchester Mental Health NHS Foundation Trust, Manchester, UK
| | - Shruti Garg
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.,Manchester Academic Health Science Centre, Manchester, UK.,Manchester University NHS Foundation Trust, Manchester, UK.,Greater Manchester Mental Health NHS Foundation Trust, Manchester, UK
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13
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Mouse strain differences in SSRI sensitivity correlate with serotonin transporter binding and function. Sci Rep 2017; 7:8631. [PMID: 28819255 PMCID: PMC5561191 DOI: 10.1038/s41598-017-08953-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 07/17/2017] [Indexed: 01/17/2023] Open
Abstract
Selective serotonin reuptake inhibitors (SSRIs) bind 5-HT transporters, leading to the accumulation of 5-HT and amelioration of depression. Although different mouse strains show varying sensitivity to SSRIs in mouse models of depression, the underlying mechanism of these strain differences remains unclear. Here, the SSRI citalopram dose-dependently reduced immobility time in both the FST and TST in DBA/2J mice but not C57BL/6J mice, whereas fluoxetine showed the opposite results. Paroxetine similarly reduced immobility time in both strains. The affinity of citalopram for the 5-HT transporter was 700-fold higher in DBA/2J mice than in C57BL/6J mice, whereas the affinity of fluoxetine was 100-fold higher in C57BL/6J mice than in DBA/2J mice. Furthermore, high citalopram concentrations were required for [3H]5-HT uptake in C57BL/6J but not in DBA/2J mouse cortical synaptosomes, whereas fluoxetine showed the opposite results. The effects of paroxetine on 5-HT transporter binding and synaptosomal 5-HT uptake were similar in the two strains. These results suggest that immobility duration depends on 5-HT transporter binding levels, which lead to apparent strain differences in immobility time in the FST and TST. Furthermore, differences in 5-HT transporter binding may cause variations in SSRI effects on behaviors.
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14
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Siemann JK, Muller CL, Forsberg CG, Blakely RD, Veenstra-VanderWeele J, Wallace MT. An autism-associated serotonin transporter variant disrupts multisensory processing. Transl Psychiatry 2017; 7:e1067. [PMID: 28323282 PMCID: PMC5416665 DOI: 10.1038/tp.2017.17] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 12/29/2016] [Accepted: 01/09/2017] [Indexed: 01/29/2023] Open
Abstract
Altered sensory processing is observed in many children with autism spectrum disorder (ASD), with growing evidence that these impairments extend to the integration of information across the different senses (that is, multisensory function). The serotonin system has an important role in sensory development and function, and alterations of serotonergic signaling have been suggested to have a role in ASD. A gain-of-function coding variant in the serotonin transporter (SERT) associates with sensory aversion in humans, and when expressed in mice produces traits associated with ASD, including disruptions in social and communicative function and repetitive behaviors. The current study set out to test whether these mice also exhibit changes in multisensory function when compared with wild-type (WT) animals on the same genetic background. Mice were trained to respond to auditory and visual stimuli independently before being tested under visual, auditory and paired audiovisual (multisensory) conditions. WT mice exhibited significant gains in response accuracy under audiovisual conditions. In contrast, although the SERT mutant animals learned the auditory and visual tasks comparably to WT littermates, they failed to show behavioral gains under multisensory conditions. We believe these results provide the first behavioral evidence of multisensory deficits in a genetic mouse model related to ASD and implicate the serotonin system in multisensory processing and in the multisensory changes seen in ASD.
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Affiliation(s)
- J K Siemann
- Neuroscience Program, Vanderbilt University, Nashville, TN, USA
| | - C L Muller
- Neuroscience Program, Vanderbilt University, Nashville, TN, USA
| | - C G Forsberg
- Department of Psychiatry, Vanderbilt University, Nashville, TN, USA
| | - R D Blakely
- Department of Psychiatry, Vanderbilt University, Nashville, TN, USA
- Silvio O. Conte Center for Neuroscience Research, Vanderbilt University, Nashville, TN, USA
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Jupiter, FL, USA
- Florida Atlantic University Brain Institute, Florida Atlantic University, Jupiter, FL, USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - J Veenstra-VanderWeele
- Silvio O. Conte Center for Neuroscience Research, Vanderbilt University, Nashville, TN, USA
- Department of Psychiatry, Sackler Institute for Developmental Psychobiology, Columbia University, New York, NY, USA
- Center for Autism and The Developing Brain, New York Presbyterian Hospital, New York, NY, USA
- New York State Psychiatric Institute, New York, NY, USA
| | - M T Wallace
- Department of Psychiatry, Vanderbilt University, Nashville, TN, USA
- Silvio O. Conte Center for Neuroscience Research, Vanderbilt University, Nashville, TN, USA
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
- Department of Hearing and Speech Sciences, Vanderbilt University, Nashville, TN, USA
- Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN, USA
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15
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Muller CL, Anacker AMJ, Rogers TD, Goeden N, Keller EH, Forsberg CG, Kerr TM, Wender CLA, Anderson GM, Stanwood GD, Blakely RD, Bonnin A, Veenstra-VanderWeele J. Impact of Maternal Serotonin Transporter Genotype on Placental Serotonin, Fetal Forebrain Serotonin, and Neurodevelopment. Neuropsychopharmacology 2017; 42:427-436. [PMID: 27550733 PMCID: PMC5399236 DOI: 10.1038/npp.2016.166] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Revised: 07/16/2016] [Accepted: 08/04/2016] [Indexed: 12/29/2022]
Abstract
Biomarker, neuroimaging, and genetic findings implicate the serotonin transporter (SERT) in autism spectrum disorder (ASD). Previously, we found that adult male mice expressing the autism-associated SERT Ala56 variant have altered central serotonin (5-HT) system function, as well as elevated peripheral blood 5-HT levels. Early in gestation, before midbrain 5-HT projections have reached the cortex, peripheral sources supply 5-HT to the forebrain, suggesting that altered maternal or placenta 5-HT system function could impact the developing embryo. We therefore used different combinations of maternal and embryo SERT Ala56 genotypes to examine effects on blood, placenta and embryo serotonin levels and neurodevelopment at embryonic day E14.5, when peripheral sources of 5-HT predominate, and E18.5, when midbrain 5-HT projections have reached the forebrain. Maternal SERT Ala56 genotype was associated with decreased placenta and embryonic forebrain 5-HT levels at E14.5. Low 5-HT in the placenta persisted, but forebrain levels normalized by E18.5. Maternal SERT Ala56 genotype effects on forebrain 5-HT levels were accompanied by a broadening of 5-HT-sensitive thalamocortical axon projections. In contrast, no effect of embryo genotype was seen in concepti from heterozygous dams. Blood 5-HT levels were dynamic across pregnancy and were increased in SERT Ala56 dams at E14.5. Placenta RNA sequencing data at E14.5 indicated substantial impact of maternal SERT Ala56 genotype, with alterations in immune and metabolic-related pathways. Collectively, these findings indicate that maternal SERT function impacts offspring placental 5-HT levels, forebrain 5-HT levels, and neurodevelopment.
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Affiliation(s)
| | - Allison MJ Anacker
- Department of Psychiatry, Columbia University Medical School, New York, NY, USA
| | - Tiffany D Rogers
- Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Nick Goeden
- Department of Cell and Neurobiology and Zilkha Neurogenetic Institute, University of Southern California School of Medicine, Los Angeles, CA, USA
| | - Elizabeth H Keller
- Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - C Gunnar Forsberg
- Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Travis M Kerr
- Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Carly LA Wender
- Department of Psychiatry, Columbia University Medical School, New York, NY, USA
| | - George M Anderson
- Child Study Center, Yale University School of Medicine, New Haven, CT, USA
| | - Gregg D Stanwood
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Randy D Blakely
- Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Alexandre Bonnin
- Department of Cell and Neurobiology and Zilkha Neurogenetic Institute, University of Southern California School of Medicine, Los Angeles, CA, USA
| | - Jeremy Veenstra-VanderWeele
- Department of Psychiatry, Columbia University Medical School, New York, NY, USA
- New York State Psychiatric Institute, New York, NY, USA
- Center for Autism and the Developing Brain, New York Presbyterian Hospital, New York, NY, USA
- Sackler Institute for Developmental Psychobiology, Columbia University, New York, NY, USA
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16
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Mamidala MP, Rajesh N, Rajesh V. Mass spectrometric evaluation of neurotransmitter levels in IMR 32 cell line in response to Ayurvedic medicines. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:1413-1422. [PMID: 27197034 DOI: 10.1002/rcm.7571] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 03/15/2016] [Accepted: 03/16/2016] [Indexed: 06/05/2023]
Abstract
RATIONALE Ayurvedic herbal medicines are administered as part of disease management for many neurodevelopmental disorders like Autism Spectrum Disorder (ASD) and linked comorbid challenges. The biochemistry of the behavioral abnormalities as observed in comorbid conditions is already reported to involve neurotransmitters like gamma-aminobutyric acid (GABA), serotonin (5-HT) and dopamine (DA). The aim of our study is to evaluate the effect of ayurvedic medicines on neurotransmitter levels in IMR 32. Such a study will give some insight into the molecular mechanism of the action of these medicines and help us to understand their contributions in neurotransmitter homeostasis. METHODS Solutions of Brahmi, Brahmi vati, Brahmi ghrita and Saraswata ghrita, each at 50 μM, were added to differentiated IMR 32 cells and grown for 24 h. The cell secretion was analysed by ultra-fast liquid chromatography/mass spectrometry (UFLC/MS) in electrospray ionisation (ESI) mode for the neurotransmitters DA, 5-HT and GABA. The mobile phase selected was 0.1% formic acid with 15 μg/mL Na2 -EDTA (A) and 0.1% formic acid in acetonitrile (B) introduced in the ratio of 92:8. RESULTS All neurotransmitters under study were eluted within 7 min with GABA eluting at 3.82 min, 5-HT at 4.48 min and DA at 5.47 min, respectively. Linearity was excellent with a correlation coefficient (R(2) ) of 0.999; repeatability and accuracy were also within acceptable range. All herbal drugs evaluated increased the neurotransmitter levels and Brahmi vati increased the neurotransmitter levels to a larger extent. CONCLUSIONS Decreased levels of neurotransmitters were observed in behavioral abnormalities which were also observed in children with ASD. Herbal medicines given as part of ayurvedic medicine increased the neurotransmitter levels in IMR 32. Thus, these ayurvedic medicines when prescribed to children with ASD might alleviate the abnormal behavioral symptoms by maintaining neurotransmitter homeostasis. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Madhu Poornima Mamidala
- Department of Biological Sciences, Birla Institute of Technology & Science, Pilani - Hyderabad Campus, India
| | - N Rajesh
- Department of Chemistry, Birla Institute of Technology & Science, Pilani - Hyderabad Campus, India
| | - Vidya Rajesh
- Department of Biological Sciences, Birla Institute of Technology & Science, Pilani - Hyderabad Campus, India
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17
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Kim KC, Gonzales EL, Lázaro MT, Choi CS, Bahn GH, Yoo HJ, Shin CY. Clinical and Neurobiological Relevance of Current Animal Models of Autism Spectrum Disorders. Biomol Ther (Seoul) 2016; 24:207-43. [PMID: 27133257 PMCID: PMC4859786 DOI: 10.4062/biomolther.2016.061] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 04/05/2016] [Indexed: 12/24/2022] Open
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social and communication impairments, as well as repetitive and restrictive behaviors. The phenotypic heterogeneity of ASD has made it overwhelmingly difficult to determine the exact etiology and pathophysiology underlying the core symptoms, which are often accompanied by comorbidities such as hyperactivity, seizures, and sensorimotor abnormalities. To our benefit, the advent of animal models has allowed us to assess and test diverse risk factors of ASD, both genetic and environmental, and measure their contribution to the manifestation of autistic symptoms. At a broader scale, rodent models have helped consolidate molecular pathways and unify the neurophysiological mechanisms underlying each one of the various etiologies. This approach will potentially enable the stratification of ASD into clinical, molecular, and neurophenotypic subgroups, further proving their translational utility. It is henceforth paramount to establish a common ground of mechanistic theories from complementing results in preclinical research. In this review, we cluster the ASD animal models into lesion and genetic models and further classify them based on the corresponding environmental, epigenetic and genetic factors. Finally, we summarize the symptoms and neuropathological highlights for each model and make critical comparisons that elucidate their clinical and neurobiological relevance.
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Affiliation(s)
- Ki Chan Kim
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.,Center for Neuroscience Research, SMART Institute of Advanced Biomedical Sciences, Konkuk University, Seoul 05029, Republic of Korea
| | - Edson Luck Gonzales
- Center for Neuroscience Research, SMART Institute of Advanced Biomedical Sciences, Konkuk University, Seoul 05029, Republic of Korea.,School of Medicine, Konkuk University, Seoul 05029, Republic of Korea
| | - María T Lázaro
- Program in Neurogenetics, Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Chang Soon Choi
- Center for Neuroscience Research, SMART Institute of Advanced Biomedical Sciences, Konkuk University, Seoul 05029, Republic of Korea.,School of Medicine, Konkuk University, Seoul 05029, Republic of Korea
| | - Geon Ho Bahn
- Department of Neuropsychiatry, School of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Hee Jeong Yoo
- Department of Neuropsychiatry, Seoul National University Bungdang Hospital, Seongnam 13620, Republic of Korea
| | - Chan Young Shin
- Center for Neuroscience Research, SMART Institute of Advanced Biomedical Sciences, Konkuk University, Seoul 05029, Republic of Korea.,School of Medicine, Konkuk University, Seoul 05029, Republic of Korea
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18
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Margolis KG, Li Z, Stevanovic K, Saurman V, Israelyan N, Anderson GM, Snyder I, Veenstra-VanderWeele J, Blakely RD, Gershon MD. Serotonin transporter variant drives preventable gastrointestinal abnormalities in development and function. J Clin Invest 2016; 126:2221-35. [PMID: 27111230 DOI: 10.1172/jci84877] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 03/03/2016] [Indexed: 12/31/2022] Open
Abstract
Autism spectrum disorder (ASD) is an increasingly common behavioral condition that frequently presents with gastrointestinal (GI) disturbances. It is not clear, however, how gut dysfunction relates to core ASD features. Multiple, rare hyperfunctional coding variants of the serotonin (5-HT) transporter (SERT, encoded by SLC6A4) have been identified in ASD. Expression of the most common SERT variant (Ala56) in mice increases 5-HT clearance and causes ASD-like behaviors. Here, we demonstrated that Ala56-expressing mice display GI defects that resemble those seen in mice lacking neuronal 5-HT. These defects included enteric nervous system hypoplasia, slow GI transit, diminished peristaltic reflex activity, and proliferation of crypt epithelial cells. An opposite phenotype was seen in SERT-deficient mice and in progeny of WT dams given the SERT antagonist fluoxetine. The reciprocal phenotypes that resulted from increased or decreased SERT activity support the idea that 5-HT signaling regulates enteric neuronal development and can, when disturbed, cause long-lasting abnormalities of GI function. Administration of a 5-HT4 agonist to Ala56 mice during development prevented Ala56-associated GI perturbations, suggesting that excessive SERT activity leads to inadequate 5-HT4-mediated neurogenesis. We propose that deficient 5-HT signaling during development may contribute to GI and behavioral features of ASD. The consequences of therapies targeting SERT during pregnancy warrant further evaluation.
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19
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Petra AI, Panagiotidou S, Hatziagelaki E, Stewart JM, Conti P, Theoharides TC. Gut-Microbiota-Brain Axis and Its Effect on Neuropsychiatric Disorders With Suspected Immune Dysregulation. Clin Ther 2016; 37:984-95. [PMID: 26046241 DOI: 10.1016/j.clinthera.2015.04.002] [Citation(s) in RCA: 340] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 04/04/2015] [Accepted: 04/07/2015] [Indexed: 12/15/2022]
Abstract
PURPOSE Gut microbiota regulate intestinal function and health. However, mounting evidence indicates that they can also influence the immune and nervous systems and vice versa. This article reviews the bidirectional relationship between the gut microbiota and the brain, termed the microbiota-gut-brain (MGB) axis, and discusses how it contributes to the pathogenesis of certain disorders that may involve brain inflammation. METHODS Articles were identified with a search of Medline (starting in 1980) by using the key words anxiety, attention-deficit hypersensitivity disorder (ADHD), autism, cytokines, depression, gut, hypothalamic-pituitary-adrenal (HPA) axis, inflammation, immune system, microbiota, nervous system, neurologic, neurotransmitters, neuroimmune conditions, psychiatric, and stress. FINDINGS Various afferent or efferent pathways are involved in the MGB axis. Antibiotics, environmental and infectious agents, intestinal neurotransmitters/neuromodulators, sensory vagal fibers, cytokines, and essential metabolites all convey information to the central nervous system about the intestinal state. Conversely, the hypothalamic-pituitary-adrenal axis, the central nervous system regulatory areas of satiety, and neuropeptides released from sensory nerve fibers affect the gut microbiota composition directly or through nutrient availability. Such interactions seem to influence the pathogenesis of a number of disorders in which inflammation is implicated, such as mood disorder, autism-spectrum disorders, attention-deficit hypersensitivity disorder, multiple sclerosis, and obesity. IMPLICATIONS Recognition of the relationship between the MGB axis and the neuroimmune systems provides a novel approach for better understanding and management of these disorders. Appropriate preventive measures early in life or corrective measures such as use of psychobiotics, fecal microbiota transplantation, and flavonoids are discussed.
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Affiliation(s)
- Anastasia I Petra
- Molecular Immunopharmacology and Drug Discovery Laboratory, Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, Massachusetts
| | - Smaro Panagiotidou
- Molecular Immunopharmacology and Drug Discovery Laboratory, Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, Massachusetts
| | - Erifili Hatziagelaki
- Second Department of Internal Medicine, Attikon General Hospital, Athens Medical School, Athens, Greece
| | - Julia M Stewart
- Molecular Immunopharmacology and Drug Discovery Laboratory, Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, Massachusetts
| | - Pio Conti
- Department of Medical Sciences, Immunology Division, University of Chieti, Via dei Vestini, Chieti, Italy
| | - Theoharis C Theoharides
- Molecular Immunopharmacology and Drug Discovery Laboratory, Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, Massachusetts; Department of Internal Medicine, Tufts University School of Medicine and Tufts Medical Center, Boston, Massachusetts; Department of Psychiatry, Tufts University School of Medicine and Tufts Medical Center, Boston, Massachusetts.
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20
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Terry N, Margolis KG. Serotonergic Mechanisms Regulating the GI Tract: Experimental Evidence and Therapeutic Relevance. Handb Exp Pharmacol 2016; 239:319-342. [PMID: 28035530 DOI: 10.1007/164_2016_103] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Serotonin (5-hydroxytryptamine; 5-HT) is best known as a neurotransmitter critical for central nervous system (CNS) development and function. 95% of the body's serotonin, however, is produced in the intestine where it has been increasingly recognized for its hormonal, autocrine, paracrine, and endocrine actions. This chapter provides the most current knowledge of the critical autocrine and paracrine roles of 5-HT in intestinal motility and inflammation as well as its function as a hormone in osteocyte homeostasis. Therapeutic applications in each of these areas are also discussed.
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Affiliation(s)
- Natalie Terry
- Division of Pediatric Gastroenterology, Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Kara Gross Margolis
- Division of Pediatric Gastroenterology, Department of Pediatrics, Morgan Stanley Children's Hospital, Columbia University Medical Center, New York, NY, USA.
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21
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Adamsen D, Ramaekers V, Ho HT, Britschgi C, Rüfenacht V, Meili D, Bobrowski E, Philippe P, Nava C, Van Maldergem L, Bruggmann R, Walitza S, Wang J, Grünblatt E, Thöny B. Autism spectrum disorder associated with low serotonin in CSF and mutations in the SLC29A4 plasma membrane monoamine transporter (PMAT) gene. Mol Autism 2014; 5:43. [PMID: 25802735 PMCID: PMC4370364 DOI: 10.1186/2040-2392-5-43] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 07/21/2014] [Indexed: 01/21/2023] Open
Abstract
Background Patients with autism spectrum disorder (ASD) may have low brain serotonin concentrations as reflected by the serotonin end-metabolite 5-hydroxyindolacetic acid (5HIAA) in cerebrospinal fluid (CSF). Methods We sequenced the candidate genes SLC6A4 (SERT), SLC29A4 (PMAT), and GCHFR (GFRP), followed by whole exome analysis. Results The known heterozygous p.Gly56Ala mutation in the SLC6A4 gene was equally found in the ASD and control populations. Using a genetic candidate gene approach, we identified, in 8 patients of a cohort of 248 with ASD, a high prevalence (3.2%) of three novel heterozygous non-synonymous mutations within the SLC29A4 plasma membrane monoamine transporter (PMAT) gene, c.86A > G (p.Asp29Gly) in two patients, c.412G > A (p.Ala138Thr) in five patients, and c.978 T > G (p.Asp326Glu) in one patient. Genome analysis of unaffected parents confirmed that these PMAT mutations were not de novo but inherited mutations. Upon analyzing over 15,000 normal control chromosomes, only SLC29A4 c.86A > G was found in 23 alleles (0.14%), while neither c.412G > A (<0.007%) nor c.978 T > G (<0.007%) were observed in all chromosomes analyzed, emphasizing the rareness of the three alterations. Expression of mutations PMAT-p.Ala138Thr and p.Asp326Glu in cellulae revealed significant reduced transport uptake activity towards a variety of substrates including serotonin, dopamine, and 1-methyl-4-phenylpyridinium (MPP+), while mutation p.Asp29Gly had reduced transport activity only towards MPP+. At least two ASD subjects with either the PMAT-Ala138Thr or the PMAT-Asp326Glu mutation with altered serotonin transport activity had, besides low 5HIAA in CSF, elevated serotonin levels in blood and platelets. Moreover, whole exome sequencing revealed additional alterations in these two ASD patients in mainly serotonin-homeostasis genes compared to their non-affected family members. Conclusions Our findings link mutations in SLC29A4 to the ASD population although not invariably to low brain serotonin. PMAT dysfunction is speculated to raise serotonin prenatally, exerting a negative feedback inhibition through serotonin receptors on development of serotonin networks and local serotonin synthesis. Exome sequencing of serotonin homeostasis genes in two families illustrated more insight in aberrant serotonin signaling in ASD.
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Affiliation(s)
- Dea Adamsen
- Division of Metabolism, Department of Pediatrics, University of Zürich, Zürich 8032, Switzerland.,Affiliated with the Neuroscience Center Zürich, University of Zürich and ETH Zürich (ZNZ), Zürich 8000, and the Children's Research Center (CRC), Zürich 8032, Switzerland
| | - Vincent Ramaekers
- Centre of Autism Liège and Division of Pediatric Neurology, University Hospital Liège, Liège 4000, Belgium
| | - Horace Tb Ho
- Department of Pharmaceutics, University of Washington, Seattle 98195, WA, USA
| | - Corinne Britschgi
- Division of Clinical Chemistry and Biochemistry, Department of Pediatrics, University of Zürich Zürich 8032, Switzerland
| | - Véronique Rüfenacht
- Division of Metabolism, Department of Pediatrics, University of Zürich, Zürich 8032, Switzerland
| | - David Meili
- Division of Clinical Chemistry and Biochemistry, Department of Pediatrics, University of Zürich Zürich 8032, Switzerland
| | - Elise Bobrowski
- University Clinics of Child and Adolescent Psychiatry, University of Zürich, Zürich 8050, Switzerland
| | - Paule Philippe
- Centre of Autism Liège and Division of Pediatric Neurology, University Hospital Liège, Liège 4000, Belgium
| | - Caroline Nava
- Department of Genetics, Cytogenetics and human Genetics, Pitié-Salpêtrière Hospital, Paris 75651, France
| | | | - Rémy Bruggmann
- Functional Genomics Center Zürich, ETH Zürich/University of Zürich, Zürich 8057, Switzerland.,current address: Interfaculty Bioinformatics Unit, University of Bern/Swiss Institute of Bioinformatics, Bern 3012, Switzerland
| | - Susanne Walitza
- University Clinics of Child and Adolescent Psychiatry, University of Zürich, Zürich 8050, Switzerland.,Affiliated with the Neuroscience Center Zürich, University of Zürich and ETH Zürich (ZNZ), Zürich 8000, Switzerland.,Affiliated with the Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich 8000, Switzerland
| | - Joanne Wang
- Department of Pharmaceutics, University of Washington, Seattle 98195, WA, USA
| | - Edna Grünblatt
- University Clinics of Child and Adolescent Psychiatry, University of Zürich, Zürich 8050, Switzerland.,Affiliated with the Neuroscience Center Zürich, University of Zürich and ETH Zürich (ZNZ), Zürich 8000, Switzerland
| | - Beat Thöny
- Division of Metabolism, Department of Pediatrics, University of Zürich, Zürich 8032, Switzerland.,Affiliated with the Neuroscience Center Zürich, University of Zürich and ETH Zürich (ZNZ), Zürich 8000, and the Children's Research Center (CRC), Zürich 8032, Switzerland.,Division of Clinical Chemistry and Biochemistry, Department of Pediatrics, University of Zürich Zürich 8032, Switzerland.,Affiliated with the Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich 8000, Switzerland
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22
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Rose'meyer R. A review of the serotonin transporter and prenatal cortisol in the development of autism spectrum disorders. Mol Autism 2013; 4:37. [PMID: 24103554 PMCID: PMC3852299 DOI: 10.1186/2040-2392-4-37] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 09/13/2013] [Indexed: 01/28/2023] Open
Abstract
The diagnosis of autism spectrum disorder (ASD) during early childhood has a profound effect not only on young children but on their families. Aside from the physical and behavioural issues that need to be dealt with, there are significant emotional and financial costs associated with living with someone diagnosed with ASD. Understanding how autism occurs will assist in preparing families to deal with ASD, if not preventing or lessening its occurrence. Serotonin plays a vital role in the development of the brain during the prenatal and postnatal periods, yet very little is known about the serotonergic systems that affect children with ASD. This review seeks to provide an understanding of the biochemistry and physiological actions of serotonin and its termination of action through the serotonin reuptake transporter (SERT). Epidemiological studies investigating prenatal conditions that can increase the risk of ASD describe a number of factors which elevate plasma cortisol levels causing such symptoms during pregnancy such as hypertension, gestational diabetes and depression. Because cortisol plays an important role in driving dysregulation of serotonergic signalling through elevating SERT production in the developing brain, it is also necessary to investigate the physiological functions of cortisol, its action during gestation and metabolic syndromes.
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Affiliation(s)
- Roselyn Rose'meyer
- School of Medical Sciences, Griffith University, Gold Coast Campus, Parklands Drive, Southport, Queensland 4222, Australia.
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23
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Kerr TM, Muller CL, Miah M, Jetter CS, Pfeiffer R, Shah C, Baganz N, Anderson GM, Crawley JN, Sutcliffe JS, Blakely RD, Veenstra-Vanderweele J. Genetic background modulates phenotypes of serotonin transporter Ala56 knock-in mice. Mol Autism 2013; 4:35. [PMID: 24083388 PMCID: PMC3851031 DOI: 10.1186/2040-2392-4-35] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 08/27/2013] [Indexed: 12/25/2022] Open
Abstract
Background Previously, we identified multiple, rare serotonin (5-HT) transporter (SERT) variants in children with autism spectrum disorder (ASD). Although in our study the SERT Ala56 variant was over-transmitted to ASD probands, it was also seen in some unaffected individuals, suggesting that associated ASD risk is influenced by the epistatic effects of other genetic variation. Subsequently, we established that mice expressing the SERT Ala56 variant on a 129S6/S4 genetic background display multiple biochemical, physiological and behavioral changes, including hyperserotonemia, altered 5-HT receptor sensitivity, and altered social, communication, and repetitive behavior. Here we explore the effects of genetic background on SERT Ala56 knock-in phenotypes. Methods To explore the effects of genetic background, we backcrossed SERT Ala56 mice on the 129 background into a C57BL/6 (B6) background to achieve congenic B6 SERT Ala56 mice, and assessed autism-relevant behavior, including sociability, ultrasonic vocalizations, and repetitive behavior in the home cage, as well as serotonergic phenotypes, including whole blood serotonin levels and serotonin receptor sensitivity. Results One consistent phenotype between the two strains was performance in the tube test for dominance, where mutant mice displayed a greater tendency to withdraw from a social encounter in a narrow tube as compared to wildtype littermate controls. On the B6 background, mutant pup ultrasonic vocalizations were significantly increased, in contrast to decreased vocalizations seen previously on the 129 background. Several phenotypes seen on the 129 background were reduced or absent when the mutation was placed on the B6 background, including hyperserotonemia, 5-HT receptor hypersensivity, and repetitive behavior. Conclusions Our findings provide a cogent example of how epistatic interactions can modulate the impact of functional genetic variation and suggest that some aspects of social behavior may be especially sensitive to changes in SERT function. Finally, these results provide a platform for the identification of genes that may modulate the risk of ASD in humans.
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Affiliation(s)
- Travis M Kerr
- Department of Psychiatry, Vanderbilt University, 465 21st Ave S, Nashville, TN 37232, USA.
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Pramod AB, Foster J, Carvelli L, Henry LK. SLC6 transporters: structure, function, regulation, disease association and therapeutics. Mol Aspects Med 2013; 34:197-219. [PMID: 23506866 DOI: 10.1016/j.mam.2012.07.002] [Citation(s) in RCA: 194] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 07/03/2012] [Indexed: 02/08/2023]
Abstract
The SLC6 family of secondary active transporters are integral membrane solute carrier proteins characterized by the Na(+)-dependent translocation of small amino acid or amino acid-like substrates. SLC6 transporters, which include the serotonin, dopamine, norepinephrine, GABA, taurine, creatine, as well as amino acid transporters, are associated with a number of human diseases and disorders making this family a critical target for therapeutic development. In addition, several members of this family are directly involved in the action of drugs of abuse such as cocaine, amphetamines, and ecstasy. Recent advances providing structural insight into this family have vastly accelerated our ability to study these proteins and their involvement in complex biological processes.
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Affiliation(s)
- Akula Bala Pramod
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58203, United States
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25
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Campbell NG, Zhu CB, Lindler KM, Yaspan BL, Kistner-Griffin E. Rare coding variants of the adenosine A3 receptor are increased in autism: on the trail of the serotonin transporter regulome. Mol Autism 2013; 4:28. [PMID: 23953133 PMCID: PMC3882891 DOI: 10.1186/2040-2392-4-28] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 07/30/2013] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Rare genetic variation is an important class of autism spectrum disorder (ASD) risk factors and can implicate biological networks for investigation. Altered serotonin (5-HT) signaling has been implicated in ASD, and we and others have discovered multiple, rare, ASD-associated variants in the 5-HT transporter (SERT) gene leading to elevated 5-HT re-uptake and perturbed regulation. We hypothesized that loci encoding SERT regulators harbor variants that impact SERT function and/or regulation and therefore could contribute to ASD risk. The adenosine A3 receptor (A3AR) regulates SERT via protein kinase G (PKG) and other signaling pathways leading to enhanced SERT surface expression and catalytic activity. METHODS To test our hypothesis, we asked whether rare variants in the A3AR gene (ADORA3) were increased in ASD cases vs. controls. Discovery sequencing in a case-control sample and subsequent analysis of comparison exome sequence data were conducted. We evaluated the functional impact of two variants from the discovery sample on A3AR signaling and SERT activity. RESULTS Sequencing discovery showed an increase of rare coding variants in cases vs. controls (P=0.013). While comparison exome sequence data did not show a significant enrichment (P=0.071), combined analysis strengthened evidence for association (P=0.0025). Two variants discovered in ASD cases (Leu90Val and Val171Ile) lie in or near the ligand-binding pocket, and Leu90Val was enriched individually in cases (P=0.040). In vitro analysis of cells expressing Val90-A3AR revealed elevated basal cGMP levels compared with the wildtype receptor. Additionally, a specific A3AR agonist increased cGMP levels across the full time course studied in Val90-A3AR cells, compared to wildtype receptor. In Val90-A3AR/SERT co-transfections, agonist stimulation elevated SERT activity over the wildtype receptor with delayed 5-HT uptake activity recovery. In contrast, Ile171-A3AR was unable to support agonist stimulation of SERT. Although both Val90 and Ile171 were present in greater numbers in these ASD cases, segregation analysis in families showed incomplete penetrance, consistent with other rare ASD risk alleles. CONCLUSIONS Our results validate the hypothesis that the SERT regulatory network harbors rare, functional variants that impact SERT activity and regulation in ASD, and encourages further investigation of this network for other variation that may impact ASD risk.
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Affiliation(s)
- Nicholas G Campbell
- Department of Molecular Physiology & Biophysics and Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, USA
| | - Chong-Bin Zhu
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, USA
| | - Kathryn M Lindler
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, USA
| | - Brian L Yaspan
- Department of Molecular Physiology & Biophysics and Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, USA
| | - Emily Kistner-Griffin
- Biostatistics and Epidemiology, Medical University of South Carolina, Charleston, SC 29425, USA
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26
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The serotonin transporter gene is a substrate for age and stress dependent epigenetic regulation in rhesus macaque brain: potential roles in genetic selection and gene × environment interactions. Dev Psychopathol 2013; 24:1391-400. [PMID: 23062305 DOI: 10.1017/s0954579412000788] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In humans, it has been demonstrated that the serotonin transporter linked polymorphic region (5-HTTLPR) genotype moderates risk in the face of adversity. One mechanism by which stress could interact with genotype is via epigenetic modifications. We wanted to examine whether stress interacted with genotype to predict binding of a histone 3 protein trimethylated at lysine 3 (H3K4me3) that marks active promoters. The brains (N = 61) of male rhesus macaques that had been reared in the presence or absence of stress were archived and the hippocampusi dissected. Chromatin immunoprecipitation was performed with an antibody against H3K4me3 followed by sequencing on a SolexaG2A. The effects of age, genotype (5-HTTLPR long/long vs. short), and stress exposure (peer-reared vs. mother-reared) on levels of H3K4me3 binding were determined. We found effects of age and stress exposure. There was a decline in H3K4me3 from preadolescence to postadolescence and lower levels in peer-reared monkeys and no effects of genotype. When we controlled for age, however, we found that there were effects of 5-HTTLPR genotype and rearing condition on H3K4me3 binding. In a larger sample, we observed that cerebrospinal fluid 5-hydroxyindoleacetic acid levels were subject to interactive effects among age, rearing history, and genotype. Genes containing both genetic selection and epigenetic regulation may be particularly important in stress adaptation and development. We find evidence for selection at the solute carrier family C6 member 4 gene and observe epigenetic reorganization according to genotype, stress, and age. These data suggest that developmental stage may moderate effects of stress and serotonin transporter genotype in the emergence of alternative adaptation strategies and in the vulnerability to developmental or psychiatric disorders.
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Autism gene variant causes hyperserotonemia, serotonin receptor hypersensitivity, social impairment and repetitive behavior. Proc Natl Acad Sci U S A 2012; 109:5469-74. [PMID: 22431635 DOI: 10.1073/pnas.1112345109] [Citation(s) in RCA: 230] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fifty years ago, increased whole-blood serotonin levels, or hyperserotonemia, first linked disrupted 5-HT homeostasis to Autism Spectrum Disorders (ASDs). The 5-HT transporter (SERT) gene (SLC6A4) has been associated with whole blood 5-HT levels and ASD susceptibility. Previously, we identified multiple gain-of-function SERT coding variants in children with ASD. Here we establish that transgenic mice expressing the most common of these variants, SERT Ala56, exhibit elevated, p38 MAPK-dependent transporter phosphorylation, enhanced 5-HT clearance rates and hyperserotonemia. These effects are accompanied by altered basal firing of raphe 5-HT neurons, as well as 5HT(1A) and 5HT(2A) receptor hypersensitivity. Strikingly, SERT Ala56 mice display alterations in social function, communication, and repetitive behavior. Our efforts provide strong support for the hypothesis that altered 5-HT homeostasis can impact risk for ASD traits and provide a model with construct and face validity that can support further analysis of ASD mechanisms and potentially novel treatments.
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28
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Dykens EM, Lee E, Roof E. Prader-Willi syndrome and autism spectrum disorders: an evolving story. J Neurodev Disord 2011; 3:225-37. [PMID: 21858456 PMCID: PMC3261277 DOI: 10.1007/s11689-011-9092-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Accepted: 07/26/2011] [Indexed: 11/04/2022] Open
Abstract
Prader-Willi syndrome (PWS) is well-known for its genetic and phenotypic complexities. Caused by a lack of paternally derived imprinted material on chromosome 15q11-q13, individuals with PWS have mild to moderate intellectual disabilities, repetitive and compulsive behaviors, skin picking, tantrums, irritability, hyperphagia, and increased risks of obesity. Many individuals also have co-occurring autism spectrum disorders (ASDs), psychosis, and mood disorders. Although the PWS 15q11-q13 region confers risks for autism, relatively few studies have assessed autism symptoms in PWS or directly compared social, behavioral, and cognitive functioning across groups with autism or PWS. This article identifies areas of phenotypic overlap and difference between PWS and ASD in core autism symptoms and in such comorbidities as psychiatric disorders, and dysregulated sleep and eating. Though future studies are needed, PWS provides a promising alternative lens into specific symptoms and comorbidities of autism.
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Affiliation(s)
- Elisabeth M Dykens
- Departments of Psychology and Human Development, Pediatrics and Psychiatry, Vanderbilt University, Vanderbilt Kennedy Center, Nashville, TN, USA,
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29
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Natural and engineered coding variation in antidepressant-sensitive serotonin transporters. Neuroscience 2011; 197:28-36. [PMID: 21893166 DOI: 10.1016/j.neuroscience.2011.08.056] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 08/23/2011] [Accepted: 08/24/2011] [Indexed: 12/17/2022]
Abstract
The presynaptic serotonin (5-HT) transporter (SERT) is a key regulator of 5-HT signaling and is a major target for antidepressant medications and psychostimulants. In recent years, studies of natural and engineered genetic variation in SERT have provided new opportunities to understand structural dimensions of drug interactions and regulation of the transporter, to explore 5-HT contributions to antidepressant action, and to assess the impact of SERT-mediated 5-HT contributions to neuropsychiatric disorders. Here we review three examples from our recent studies where genetic changes in SERT, identified or engineered, have led to new models, findings, and theories that cast light on new dimensions of 5-HT action in the CNS and periphery. First, we review our work to identify specific residues through which SERT recognizes antagonists, and the conversion of this knowledge to the creation of mice lacking high-affinity antidepressant and cocaine sensitivity. Second, we discuss our studies of functional coding variation in SERT that exists in commonly used strains of inbred mice, and how this variation is beginning to reveal novel 5-HT-associated phenotypes. Third, we review our identification and functional characterization of multiple, hyperactive SERT coding variants in subjects with autism. Each of these activities has driven the development of new model systems that can be further exploited to understand the contribution of 5-HT signaling to risk for neuropsychiatric disorders and their treatment.
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30
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Takumi T. The neurobiology of mouse models syntenic to human chromosome 15q. J Neurodev Disord 2011; 3:270-81. [PMID: 21789598 PMCID: PMC3261275 DOI: 10.1007/s11689-011-9088-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 07/12/2011] [Indexed: 11/26/2022] Open
Abstract
Autism is a neurodevelopmental disorder that manifests in childhood as social behavioral abnormalities, such as abnormal social interaction, impaired communication, and restricted interest or behavior. Of the known causes of autism, duplication of human chromosome 15q11–q13 is the most frequently associated cytogenetic abnormality. Chromosome 15q11–q13 is also known to include imprinting genes. In terms of neuroscience, it contains interesting genes such as Necdin, Ube3a, and a cluster of GABAA subunits as well as huge clusters of non-coding RNAs (small nucleolar RNAs, snoRNAs). Phenotypic analyses of mice genetically or chromosomally engineered for each gene or their clusters on a region of mouse chromosome seven syntenic to human 15q11–q13 indicate that this region may be involved in social behavior, serotonin metabolism, and weight control. Further studies using these models will provide important clues to the pathophysiology of autism. This review overviews phenotypes of mouse models of genes in 15q11–q13 and their relationships to autism.
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Affiliation(s)
- Toru Takumi
- Laboratory of Integrative Bioscience, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami, Hiroshima, 734-8553, Japan,
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31
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Kristensen AS, Andersen J, Jørgensen TN, Sørensen L, Eriksen J, Loland CJ, Strømgaard K, Gether U. SLC6 neurotransmitter transporters: structure, function, and regulation. Pharmacol Rev 2011; 63:585-640. [PMID: 21752877 DOI: 10.1124/pr.108.000869] [Citation(s) in RCA: 586] [Impact Index Per Article: 45.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The neurotransmitter transporters (NTTs) belonging to the solute carrier 6 (SLC6) gene family (also referred to as the neurotransmitter-sodium-symporter family or Na(+)/Cl(-)-dependent transporters) comprise a group of nine sodium- and chloride-dependent plasma membrane transporters for the monoamine neurotransmitters serotonin (5-hydroxytryptamine), dopamine, and norepinephrine, and the amino acid neurotransmitters GABA and glycine. The SLC6 NTTs are widely expressed in the mammalian brain and play an essential role in regulating neurotransmitter signaling and homeostasis by mediating uptake of released neurotransmitters from the extracellular space into neurons and glial cells. The transporters are targets for a wide range of therapeutic drugs used in treatment of psychiatric diseases, including major depression, anxiety disorders, attention deficit hyperactivity disorder and epilepsy. Furthermore, psychostimulants such as cocaine and amphetamines have the SLC6 NTTs as primary targets. Beginning with the determination of a high-resolution structure of a prokaryotic homolog of the mammalian SLC6 transporters in 2005, the understanding of the molecular structure, function, and pharmacology of these proteins has advanced rapidly. Furthermore, intensive efforts have been directed toward understanding the molecular and cellular mechanisms involved in regulation of the activity of this important class of transporters, leading to new methodological developments and important insights. This review provides an update of these advances and their implications for the current understanding of the SLC6 NTTs.
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Affiliation(s)
- Anders S Kristensen
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark.
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32
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Blakely RD, Veenstra-VanderWeele J. Genetic indeterminism, the 5-HTTLPR, and the paths forward in neuropsychiatric genetics. ACTA ACUST UNITED AC 2011; 68:457-8. [PMID: 21536974 DOI: 10.1001/archgenpsychiatry.2011.34] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Randy D Blakely
- Departments of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-8548, USA.
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Daws LC, Gould GG. Ontogeny and regulation of the serotonin transporter: providing insights into human disorders. Pharmacol Ther 2011; 131:61-79. [PMID: 21447358 DOI: 10.1016/j.pharmthera.2011.03.013] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 03/11/2011] [Indexed: 12/17/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) was one of the first neurotransmitters for which a role in development was identified. Pharmacological and gene knockout studies have revealed a critical role for 5-HT in numerous processes, including cell division, neuronal migration, differentiation and synaptogenesis. An excess in brain 5-HT appears to be mechanistically linked to abnormal brain development, which in turn is associated with neurological disorders. Ambient levels of 5-HT are controlled by a vast orchestra of proteins, including a multiplicity of pre- and post-synaptic 5-HT receptors, heteroreceptors, enzymes and transporters. The 5-HT transporter (SERT, 5-HTT) is arguably the most powerful regulator of ambient extracellular 5-HT. SERT is the high-affinity uptake mechanism for 5-HT and exerts tight control over the strength and duration of serotonergic neurotransmission. Perturbation of its expression level or function has been implicated in many diseases, prominent among them are psychiatric disorders. This review synthesizes existing information on the ontogeny of SERT during embryonic and early postnatal development though adolescence, along with factors that influence its expression and function during these critical developmental windows. We integrate this knowledge to emphasize how inappropriate SERT expression or its dysregulation may be linked to the pathophysiology of psychiatric, cardiovascular and gastrointestinal diseases.
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Affiliation(s)
- Lynette C Daws
- Department of Physiology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, MC 7756, San Antonio, TX 78229-3900, USA.
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Robertson HR, Feng G. Annual Research Review: Transgenic mouse models of childhood-onset psychiatric disorders. J Child Psychol Psychiatry 2011; 52:442-75. [PMID: 21309772 PMCID: PMC3075087 DOI: 10.1111/j.1469-7610.2011.02380.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Childhood-onset psychiatric disorders, such as attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), mood disorders, obsessive compulsive spectrum disorders (OCSD), and schizophrenia (SZ), affect many school-age children, leading to a lower quality of life, including difficulties in school and personal relationships that persist into adulthood. Currently, the causes of these psychiatric disorders are poorly understood, resulting in difficulty diagnosing affected children, and insufficient treatment options. Family and twin studies implicate a genetic contribution for ADHD, ASD, mood disorders, OCSD, and SZ. Identification of candidate genes and chromosomal regions associated with a particular disorder provide targets for directed research, and understanding how these genes influence the disease state will provide valuable insights for improving the diagnosis and treatment of children with psychiatric disorders. Transgenic mouse models are one important approach in the study of human diseases, allowing for the use of a variety of experimental approaches to dissect the contribution of a specific chromosomal or genetic abnormality in human disorders. While it is impossible to model an entire psychiatric disorder in a single mouse model, these models can be extremely valuable in dissecting out the specific role of a gene, pathway, neuron subtype, or brain region in a particular abnormal behavior. In this review we discuss existing transgenic mouse models for childhood-onset psychiatric disorders. We compare the strength and weakness of various transgenic mouse models proposed for each of the common childhood-onset psychiatric disorders, and discuss future directions for the study of these disorders using cutting-edge genetic tools.
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Affiliation(s)
- Holly R. Robertson
- Duke University, Neurobiology Department Durham, N.C.,Massachusetts Institute of Technology, Brain and Cognitive Sciences Department Cambridge, M.A
| | - Guoping Feng
- Duke University, Neurobiology Department Durham, N.C.,Massachusetts Institute of Technology, Brain and Cognitive Sciences Department Cambridge, M.A
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35
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Ye H, Liu J, Wu JY. Cell adhesion molecules and their involvement in autism spectrum disorder. Neurosignals 2011; 18:62-71. [PMID: 21212702 DOI: 10.1159/000322543] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 11/08/2010] [Indexed: 12/18/2022] Open
Abstract
Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders characterized by abnormalities in social interaction, language development and behavior. Recent genetic studies demonstrate that alterations in synaptic genes including those encoding cell adhesion molecules and their interaction partners play important roles in the pathogenesis of ASD. Systematic analyses of different cell adhesion molecule genes will help elucidate their normal functions and regulatory mechanisms in the establishment and maintenance of normal neural circuits and uncover genetic aberrations contributing to ASD.
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Affiliation(s)
- Haihong Ye
- The State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
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36
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Gould GG, Hensler JG, Burke TF, Benno RH, Onaivi ES, Daws LC. Density and function of central serotonin (5-HT) transporters, 5-HT1A and 5-HT2A receptors, and effects of their targeting on BTBR T+tf/J mouse social behavior. J Neurochem 2011; 116:291-303. [PMID: 21070242 PMCID: PMC3012263 DOI: 10.1111/j.1471-4159.2010.07104.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BTBR mice are potentially useful tools for autism research because their behavior parallels core social interaction impairments and restricted-repetitive behaviors. Altered regulation of central serotonin (5-HT) neurotransmission may underlie such behavioral deficits. To test this, we compared 5-HT transporter (SERT), 5-HT(1A) and 5-HT(2A) receptor densities among BTBR and C57 strains. Autoradiographic [(3) H] cyanoimipramine (1 nM) binding to SERT was 20-30% lower throughout the adult BTBR brain as compared to C57BL/10J mice. In hippocampal membrane homogenates, [(3) H] citalopram maximal binding (B(max) ) to SERT was 95 ± 13 fmol/mg protein in BTBR and 171 ± 20 fmol/mg protein in C57BL/6J mice, and the BTBR dissociation constant (K(D) ) was 2.0 ± 0.3 nM versus 1.1 ± 0.2 in C57BL/6J mice. Hippocampal 5-HT(1A) and 5-HT(2A) receptor binding was similar among strains. However, 8-OH-DPAT-stimulated [(35) S] GTPγS binding in the BTBR hippocampal CA(1) region was 28% higher, indicating elevated 5-HT(1A) capacity to activate G-proteins. In BTBR mice, the SERT blocker, fluoxetine (10 mg/kg) and the 5-HT(1A) receptor partial-agonist, buspirone (2 mg/kg) enhanced social interactions. The D(2) /5-HT(2) receptor antagonist, risperidone (0.1 mg/kg) reduced marble burying, but failed to improve sociability. Overall, altered SERT and/or 5-HT(1A) functionality in hippocampus could contribute to the relatively low sociability of BTBR mice.
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MESH Headings
- Animals
- Brain/drug effects
- Brain/metabolism
- Brain/physiology
- Buspirone/pharmacology
- Fluoxetine/pharmacology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred Strains
- Protein Binding/physiology
- Protein Transport
- Receptor, Serotonin, 5-HT1A/metabolism
- Receptor, Serotonin, 5-HT1A/physiology
- Receptor, Serotonin, 5-HT2A/metabolism
- Receptor, Serotonin, 5-HT2A/physiology
- Serotonin Plasma Membrane Transport Proteins/metabolism
- Serotonin Plasma Membrane Transport Proteins/physiology
- Social Behavior
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Affiliation(s)
- Georgianna G Gould
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA.
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