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Janušonis S, Haiman JH, Metzler R, Vojta T. Predicting the distribution of serotonergic axons: a supercomputing simulation of reflected fractional Brownian motion in a 3D-mouse brain model. Front Comput Neurosci 2023; 17:1189853. [PMID: 37265780 PMCID: PMC10231035 DOI: 10.3389/fncom.2023.1189853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 04/24/2023] [Indexed: 06/03/2023] Open
Abstract
The self-organization of the brain matrix of serotonergic axons (fibers) remains an unsolved problem in neuroscience. The regional densities of this matrix have major implications for neuroplasticity, tissue regeneration, and the understanding of mental disorders, but the trajectories of its fibers are strongly stochastic and require novel conceptual and analytical approaches. In a major extension to our previous studies, we used a supercomputing simulation to model around one thousand serotonergic fibers as paths of superdiffusive fractional Brownian motion (FBM), a continuous-time stochastic process. The fibers produced long walks in a complex, three-dimensional shape based on the mouse brain and reflected at the outer (pial) and inner (ventricular) boundaries. The resultant regional densities were compared to the actual fiber densities in the corresponding neuroanatomically-defined regions. The relative densities showed strong qualitative similarities in the forebrain and midbrain, demonstrating the predictive potential of stochastic modeling in this system. The current simulation does not respect tissue heterogeneities but can be further improved with novel models of multifractional FBM. The study demonstrates that serotonergic fiber densities can be strongly influenced by the geometry of the brain, with implications for brain development, plasticity, and evolution.
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Affiliation(s)
- Skirmantas Janušonis
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Justin H. Haiman
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Ralf Metzler
- Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany
- Asia Pacific Center for Theoretical Physics, Pohang, South Korea
| | - Thomas Vojta
- Department of Physics, Missouri University of Science and Technology, Rolla, MO, United States
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Examining litter specific variability in mice and its impact on neurodevelopmental studies. Neuroimage 2023; 269:119888. [PMID: 36681136 DOI: 10.1016/j.neuroimage.2023.119888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 01/07/2023] [Accepted: 01/17/2023] [Indexed: 01/21/2023] Open
Abstract
Our current understanding of litter variability in neurodevelopmental studies using mice may limit translation of neuroscientific findings. Higher variance of measures across litters than within, often termed intra-litter likeness, may be attributable to both pre- and postnatal environment. This study aimed to assess the litter-effect within behavioral assessments (2 timepoints) and anatomy using T1-weighted magnetic resonance images across 72 brain region volumes (4 timepoints) (36 C57bl/6J inbred mice; 7 litters: 19F/17M). Between-litter comparisons of brain and behavioral measures and their associations were evaluated using univariate and multivariate techniques. A power analysis using simulation methods was then performed on modeled neurodevelopment and to evaluate trade-offs between number-of-litters, number-of-mice-per-litter, and sample size. Our results show litter-specific developmental effects, from the adolescent period to adulthood for brain structure volumes and behaviors, and for their associations in adulthood. Our power simulation analysis suggests increasing the number-of-litters in experimental designs to achieve the smallest total sample size necessary for detecting different rates of change in specific brain regions. Our results demonstrate how litter-specific effects may influence development and that increasing the litters to the total sample size ratio should be strongly considered when designing neurodevelopmental studies.
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Yeh YM, Lye XY, Lin HY, Wong JY, Wu CC, Huang CL, Tsai YC, Wang LC. Effects of Lactiplantibacillus plantarum PS128 on alleviating canine aggression and separation anxiety. Appl Anim Behav Sci 2022. [DOI: 10.1016/j.applanim.2022.105569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Akillioglu K, Karadepe M. Effect Neonatal Ketamine Treatment on Exploratory and Anxiety-like Behaviours in Adulthood. CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE 2021; 19:93-103. [PMID: 33508792 PMCID: PMC7851452 DOI: 10.9758/cpn.2021.19.1.93] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 05/17/2020] [Accepted: 06/15/2020] [Indexed: 11/18/2022]
Affiliation(s)
- Kübra Akillioglu
- Division of Neurophysiology, Department of Physiology, Medical Faculty, University of Cukurova, Turkey
| | - Mustafa Karadepe
- Department of Internal Medicine, Medical Faculty of Cukurova, Adana, Turkey
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Liao JF, Cheng YF, Li SW, Lee WT, Hsu CC, Wu CC, Jeng OJ, Wang S, Tsai YC. Lactobacillus plantarum PS128 ameliorates 2,5-Dimethoxy-4-iodoamphetamine-induced tic-like behaviors via its influences on the microbiota-gut-brain-axis. Brain Res Bull 2019; 153:59-73. [PMID: 31351942 DOI: 10.1016/j.brainresbull.2019.07.027] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 07/21/2019] [Accepted: 07/23/2019] [Indexed: 12/18/2022]
Abstract
We previously reported a novel psychobiotic strain of Lactobacillus plantarum PS128 (PS128) which could ameliorate anxiety-like& depression-like behaviors and modulate cerebral dopamine (DA) and serotonin (5-HT) in mice. Here, we examine the possibility of using PS128 administration to improve tic-like behaviors by using a 5-HT2A and 5-HT2C receptor agonist 2,5-Dimethoxy-4-iodoamphetamine (DOI). PS128 was orally administered to male Wistar rat for 2 weeks before two daily DOI injections. We recorded the behaviors immediately after the second DOI injection and compared the results with control and haloperidol treatment groups. PS128 significantly reduced tic-like behaviors and pre-pulse inhibition deficit in a threshold-dose of 109 CFU per day. Brain tissue analysis showed that DOI induced abnormal DA efflux in the striatum and prefrontal cortex, while PS128 ingestion improved DA metabolism and increased norepinephrine (NE) levels in these two regions. In addition, PS128 ingestion increased DA transporter and β-arrestin expressions and decreased DOI-induced phosphorylation of DA and cAMP regulated phosphoprotein of molecular weight 32 kDa (DARPP-32) at Thr34 and extracellular regulated protein kinases (ERK). PS128 ingestion also modulated peripheral 5-HT levels and shaped the cecal microbiota composition, which helps to alleviate DOI-induced dysbiosis. These results suggested that PS128 ameliorated DOI-induced tic-like hyper-active behaviors via stabilizing cerebral dopaminergic pathways through its modulation of host's microbiota-gut-brain axis. Thus, we believe there are potentials for utilizing psychobiotics to improve syndromes caused by DA dysregulation in DA-related neurological disorders and movement disorders such as Tourette syndrome.
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Affiliation(s)
- Jian-Fu Liao
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, 155, Section 2, Linong Street, Beitou Dist., Taipei City 11221, Taiwan, ROC.
| | - Yun-Fang Cheng
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, 155, Section 2, Linong Street, Beitou Dist., Taipei City 11221, Taiwan, ROC; Microbiome Research Center, National Yang-Ming University, 155, Section 2, Linong Street, Beitou Dist., Taipei City 11221, Taiwan, ROC; Bened Biomedical Co., Ltd., 2F-2, No. 129, Sec. 2, Zhongshan N. Rd., Zhongshan Dist., Taipei City 104, Taiwan, ROC.
| | - Shiao-Wen Li
- Molecular Medicine Research Center, Chang Gung University, No. 259, Wenhua 1st Rd., Guishan District, Taoyuan City 33302, Taiwan, ROC.
| | - Wang-Tso Lee
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Zhongshan S. Rd., Zhongzheng Dist., Taipei City 100, Taiwan, ROC.
| | - Chih-Chieh Hsu
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, 155, Section 2, Linong Street, Beitou Dist., Taipei City 11221, Taiwan, ROC; Bened Biomedical Co., Ltd., 2F-2, No. 129, Sec. 2, Zhongshan N. Rd., Zhongshan Dist., Taipei City 104, Taiwan, ROC.
| | - Chien-Chen Wu
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, 155, Section 2, Linong Street, Beitou Dist., Taipei City 11221, Taiwan, ROC; Bened Biomedical Co., Ltd., 2F-2, No. 129, Sec. 2, Zhongshan N. Rd., Zhongshan Dist., Taipei City 104, Taiwan, ROC.
| | - One-Jang Jeng
- Bened Biomedical Co., Ltd., 2F-2, No. 129, Sec. 2, Zhongshan N. Rd., Zhongshan Dist., Taipei City 104, Taiwan, ROC.
| | - Sabrina Wang
- Institute of Anatomy and Cell Biology, National Yang-Ming University, 155, Section 2, Linong Street, Beitou Dist., Taipei City 11221, Taiwan, ROC.
| | - Ying-Chieh Tsai
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, 155, Section 2, Linong Street, Beitou Dist., Taipei City 11221, Taiwan, ROC; Microbiome Research Center, National Yang-Ming University, 155, Section 2, Linong Street, Beitou Dist., Taipei City 11221, Taiwan, ROC.
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Chen K, Kardys A, Chen Y, Flink S, Tabakoff B, Shih JC. Altered gene expression in early postnatal monoamine oxidase A knockout mice. Brain Res 2017; 1669:18-26. [PMID: 28535982 PMCID: PMC5531263 DOI: 10.1016/j.brainres.2017.05.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 04/10/2017] [Accepted: 05/16/2017] [Indexed: 11/19/2022]
Abstract
We reported previously that monoamine oxidase (MAO) A knockout (KO) mice show increased serotonin (5-hydroxytryptamine, 5-HT) levels and autistic-like behaviors characterized by repetitive behaviors, and anti-social behaviors. We showed that administration of the serotonin synthesis inhibitor para-chlorophenylalanine (pCPA) from post-natal day 1 (P1) through 7 (P7) in MAO A KO mice reduced the serotonin level to normal and reverses the repetitive behavior. These results suggested that the altered gene expression at P1 and P7 may be important for the autistic-like behaviors seen in MAO A KO mice and was studied here. In this study, Affymetrix mRNA array data for P1 and P7 MAO A KO mice were analyzed using Partek Genomics Suite and Ingenuity Pathways Analysis to identify genes differentially expressed versus wild-type and assess their functions and relationships. The number of significant differentially expressed genes (DEGs) varied with age: P1 (664) and P7 (3307) [false discovery rate (FDR) <0.05, fold-change (FC) >1.5 for autism-linked genes and >2.0 for functionally categorized genes]. Eight autism-linked genes were differentially expressed in P1 (upregulated: NLGN3, SLC6A2; down-regulated: HTR2C, MET, ADSL, MECP2, ALDH5A1, GRIN3B) while four autism-linked genes were differentially expressed at P7 (upregulated: HTR2B; downregulated: GRIN2D, GRIN2B, CHRNA4). Many other genes involved in neurodevelopment, apoptosis, neurotransmission, and cognitive function were differentially expressed at P7 in MAO A KO mice. This result suggests that modulation of these genes by the increased serotonin may lead to neurodevelopmental alteration in MAO A KO mice and results in autistic-like behaviors.
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Affiliation(s)
- Kevin Chen
- Dept. of Pharmacology & Pharmaceutical Science, School of Pharmacy, Los Angeles, CA 90089, United States
| | - Abbey Kardys
- Dept. of Pharmacology & Pharmaceutical Science, School of Pharmacy, Los Angeles, CA 90089, United States
| | - Yibu Chen
- Norris Medical Library, University of Southern California, Los Angeles, CA 90089, United States
| | - Stephen Flink
- University of Colorado Health Science Center, Denver, CO 80262, United States
| | - Boris Tabakoff
- University of Colorado Health Science Center, Denver, CO 80262, United States
| | - Jean C Shih
- Dept. of Pharmacology & Pharmaceutical Science, School of Pharmacy, Los Angeles, CA 90089, United States; USC-Taiwan Center for Translational Research, University of Southern California, Los Angeles, CA 90089, United States; Dept. of Cell & Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, United States.
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Golub MS, Bulleri AM, Hogrefe CE, Sherwood RJ. Bone growth in juvenile rhesus monkeys is influenced by 5HTTLPR polymorphisms and interactions between 5HTTLPR polymorphisms and fluoxetine. Bone 2015; 79:162-9. [PMID: 26067181 PMCID: PMC4511468 DOI: 10.1016/j.bone.2015.05.042] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 05/12/2015] [Accepted: 05/31/2015] [Indexed: 01/02/2023]
Abstract
Male rhesus monkeys received a therapeutic oral dose of the selective serotonin reuptake inhibitor (SSRI) fluoxetine daily from 1 to 3 years of age. Puberty is typically initiated between 2 and 3 years of age in male rhesus and reproductive maturity is reached at 4 years. The study group was genotyped for polymorphisms in the monoamine oxidase A (MAOA) and serotonin transporter (SERT) genes that affect serotonin neurotransmission. Growth was assessed with morphometrics at 4 month intervals and radiographs of long bones were taken at 12 month intervals to evaluate skeletal growth and maturation. No effects of fluoxetine, or MAOA or SERT genotype were found for growth during the first year of the study. Linear growth began to slow during the second year of the study and serotonin reuptake transporter (SERT) long polymorphic region (5HTTLPR) polymorphism effects with drug interactions emerged. Monkeys with two SERT 5HTTLPR L alleles (LL, putative greater transcription) had 25-39% less long bone growth, depending on the bone, than monkeys with one S and one L allele (SL). More advanced skeletal maturity was also seen in the LL group, suggesting earlier onset of puberty. An interaction between 5HTTLPR polymorphisms and fluoxetine was identified for femur and tibia growth; the 5HTTLPR effect was seen in controls (40% less growth for LL) but not in the fluoxetine treated group (10% less growth for LL). A role for serotonin in peripubertal skeletal growth and maturation has not previously been investigated but may be relevant to treatment of children with SSRIs.
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Affiliation(s)
- Mari S Golub
- Department of Environmental Toxicology, University of California, Davis, Davis, CA 95616, USA.
| | - Alicia M Bulleri
- California National Primate Research Center, University of California, Davis, Davis, CA 95616, USA
| | - Casey E Hogrefe
- California National Primate Research Center, University of California, Davis, Davis, CA 95616, USA
| | - Richard J Sherwood
- Division of Morphological Sciences and Biostatistics, Boonshoft School of Medicine, Wright State University, Dayton, OH 45434, USA
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Abstract
Network perspectives, in their emphasis on components and their interactions, might afford the best approach to the complexities of the ASD realm. Categorical approaches are unlikely to be fruitful as one should not expect to find a single or even predominant underlying cause of autism behavior across individuals. It is possible that the complex, highly interactive, heterogeneous and individualistic nature of the autism realm is intractable in terms of identifying clinically useful biomarker tests. It is hopeful from an emergenic perspective that small corrective changes in a single component of a deleterious network/configuration might have large beneficial consequences on developmental trajectories and in later treatment. It is suggested that the relationship between ASD and intellectual disability might be fundamentally different in single-gene versus nonsyndromic ASD. It is strongly stated that available biomarker "tests" for autism/ASD will do more harm than good. Finally, the serotonin-melatonin-oxidative stress-placental intersection might be an especially fruitful area of biological investigation.
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Zhang WQ, Smolik CM, Barba-Escobedo PA, Gamez M, Sanchez JJ, Javors MA, Daws LC, Gould GG. Acute dietary tryptophan manipulation differentially alters social behavior, brain serotonin and plasma corticosterone in three inbred mouse strains. Neuropharmacology 2015; 90:1-8. [PMID: 25445490 PMCID: PMC4276517 DOI: 10.1016/j.neuropharm.2014.10.024] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 10/21/2014] [Accepted: 10/26/2014] [Indexed: 12/22/2022]
Abstract
Clinical evidence indicates brain serotonin (5-HT) stores and neurotransmission may be inadequate in subpopulations of individuals with autism, and this may contribute to characteristically impaired social behaviors. Findings that depletion of the 5-HT precursor tryptophan (TRP) worsens autism symptoms support this hypothesis. Yet dietetic studies show and parents report that many children with autism consume less TRP than peers. To measure the impact of dietary TRP content on social behavior, we administered either diets devoid of TRP, with standard TRP (0.2 g%), or with 1% added TRP (1.2 g%) overnight to three mouse strains. Of these, BTBRT(+)Itpr3(tf)/J and 129S1/SvImJ consistently exhibit low preference for social interaction relative to C57BL/6. We found that TRP depletion reduced C57BL/6 and 129S social interaction preference, while TRP enhancement improved BTBR sociability (p < 0.05; N = 8-10). Subsequent marble burying did not differ among diets or strains. After behavior tests, brain TRP levels and plasma corticosterone were higher in TRP enhanced C57BL/6 and BTBR, while 5-HT levels were reduced in all strains by TRP depletion (p < 0.05; N = 4-10). Relative hyperactivity of BTBR and hypoactivity of 129S, evident in self-grooming and chamber entries during sociability tests, were uninfluenced by dietary TRP. Our findings demonstrate mouse sociability and brain 5-HT turnover are reduced by acute TRP depletion, and can be enhanced by TRP supplementation. This outcome warrants further basic and clinical studies employing biomarker combinations such as TRP metabolism and 5-HT regulated hormones to characterize conditions wherein TRP supplementation may best ameliorate sociability deficits.
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Affiliation(s)
- Wynne Q Zhang
- Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; Rice University, Houston, TX 77005, USA
| | - Corey M Smolik
- Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Priscilla A Barba-Escobedo
- Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; Texas A&M University at San Antonio, TX 78224, USA
| | - Monica Gamez
- Texas A&M University at San Antonio, TX 78224, USA
| | - Jesus J Sanchez
- Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Martin A Javors
- Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Lynette C Daws
- Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Georgianna G Gould
- Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
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Janušonis S. Serotonin dynamics in and around the central nervous system: is autism solvable without fundamental insights? Int J Dev Neurosci 2014; 39:9-15. [PMID: 24886833 DOI: 10.1016/j.ijdevneu.2014.05.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 05/20/2014] [Indexed: 12/15/2022] Open
Abstract
Altered serotonin (5-hydroxytryptamine, 5-HT) signaling has been implicated in some developmental abnormalities of autism spectrum disorder (ASD). However, the presumed role of 5-HT in ASD raises new questions in fundamental neuroscience. Specifically, it is not clear if the current piecemeal approach to 5-HT signaling in the mammalian body is effective and whether new conceptual approaches may be required. This review briefly discusses 5-HT production and circulation in the central nervous system and outside of it, especially with regard to ASD, and proposes a more encompassing approach that questions the utility of the "neurotransmitter" concept. It then introduces the idea of a generalized 5-HT packet that may offer insights into possible links between serotonergic varicosities and blood platelets. These approaches have theoretical significance, but they are also well positioned to advance our understanding of some long-standing problems in autism research.
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Affiliation(s)
- Skirmantas Janušonis
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106-9660, USA.
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Ye R, Carneiro AMD, Airey D, Sanders-Bush E, Williams RW, Lu L, Wang J, Zhang B, Blakely RD. Evaluation of heritable determinants of blood and brain serotonin homeostasis using recombinant inbred mice. GENES BRAIN AND BEHAVIOR 2013; 13:247-60. [PMID: 24102824 DOI: 10.1111/gbb.12092] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 10/01/2013] [Accepted: 10/01/2013] [Indexed: 12/31/2022]
Abstract
The biogenic amine serotonin (5-HT, 5-hydroxytryptamine) exerts powerful, modulatory control over multiple physiological functions in the brain and periphery, ranging from mood and appetite to vasoconstriction and gastrointestinal motility. In order to gain insight into shared and distinct molecular and phenotypic networks linked to variations in 5-HT homeostasis, we capitalized on the stable genetic variation present in recombinant inbred mouse strains. This family of strains, all derived from crosses between C57BL/6J and DBA/2J (BXD) parents, represents a unique, community resource with approximately 40 years of assembled phenotype data that can be exploited to explore and test causal relationships in silico. We determined levels of 5-HT and 5-hydroxyindoleacetic acid from whole blood, midbrain and thalamus/hypothalamus (diencephalon) of 38 BXD lines and both sexes. All 5-HT measures proved highly heritable in each region, although both gender and region significantly impacted between-strain correlations. Our studies identified both expected and novel biochemical, anatomical and behavioral phenotypes linked to 5-HT traits, as well as distinct quantitative trait loci. Analyses of these loci nominate a group of genes likely to contribute to gender- and region-specific capacities for 5-HT signaling. Analysis of midbrain mRNA variations across strains revealed overlapping gene expression networks linked to 5-HT synthesis and metabolism. Altogether, our studies provide a rich profile of genomic, molecular and phenotypic networks that can be queried for novel relationships contributing risk for disorders linked to perturbed 5-HT signaling.
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Affiliation(s)
- R Ye
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville
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Lazic SE, Essioux L. Improving basic and translational science by accounting for litter-to-litter variation in animal models. BMC Neurosci 2013; 14:37. [PMID: 23522086 PMCID: PMC3661356 DOI: 10.1186/1471-2202-14-37] [Citation(s) in RCA: 176] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 03/08/2013] [Indexed: 12/22/2022] Open
Abstract
Background Animals from the same litter are often more alike compared with animals from different litters. This litter-to-litter variation, or “litter effects”, can influence the results in addition to the experimental factors of interest. Furthermore, sometimes an experimental treatment can only be applied to whole litters rather than to individual offspring. An example is the valproic acid (VPA) model of autism, where VPA is administered to pregnant females thereby inducing the disease phenotype in the offspring. With this type of experiment the sample size is the number of litters and not the total number of offspring. If such experiments are not appropriately designed and analysed, the results can be severely biased as well as extremely underpowered. Results A review of the VPA literature showed that only 9% (3/34) of studies correctly determined that the experimental unit (n) was the litter and therefore made valid statistical inferences. In addition, litter effects accounted for up to 61% (p <0.001) of the variation in behavioural outcomes, which was larger than the treatment effects. In addition, few studies reported using randomisation (12%) or blinding (18%), and none indicated that a sample size calculation or power analysis had been conducted. Conclusions Litter effects are common, large, and ignoring them can make replication of findings difficult and can contribute to the low rate of translating preclinical in vivo studies into successful therapies. Only a minority of studies reported using rigorous experimental methods, which is consistent with much of the preclinical in vivo literature.
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Affiliation(s)
- Stanley E Lazic
- In Silico Lead Discovery, Novartis Institutes for Biomedical Research, Switzerland.
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