@article{AraragiMlinarBaccinietal.2013,
  author    = {Araragi, Naozumi and Mlinar, Boris and Baccini, Gilda and Gutknecht, Lise and Lesch, Klaus-Peter and Corradetti, Renato},
  title     = {Conservation of 5-HT1A receptor-mediated autoinhibition of serotonin (5-HT) neurons in mice with altered 5-HT homeostasis},
  series = {Frontiers in Neuropharmacology},
  journal   = {Frontiers in Neuropharmacology},
  doi       = {10.3389/fphar.2013.00097},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-97098},
  year      = {2013},
  abstract  = {Firing activity of serotonin (5-HT) neurons in the dorsal raphe nucleus (DRN) is controlled by inhibitory somatodendritic 5-HT1A autoreceptors. This autoinhibitory mechanism is implicated in the etiology of disorders of emotion regulation, such as anxiety disorders and depression, as well as in the mechanism of antidepressant action. Here, we investigated how persistent alterations in brain 5-HT availability affect autoinhibition in two genetically modified mouse models lacking critical mediators of serotonergic transmission: 5-HT transporter knockout (Sert-/-) and tryptophan hydroxylase-2 knockout (Tph2-/-) mice. The degree of autoinhibition was assessed by loose-seal cell-attached recording in DRN slices. First, application of the 5-HT1A-selective agonist R(+)-8-hydroxy-2-(di-n-propylamino)tetralin showed mild sensitization and marked desensitization of 5-HT1A receptors in Tph2-/- mice and Sert-/- mice, respectively. While 5-HT neurons from Tph2-/- mice did not display autoinhibition in response to L-tryptophan, autoinhibition of these neurons was unaltered in Sert-/- mice despite marked desensitization of their 5-HT1A autoreceptors. When the Tph2-dependent 5-HT synthesis step was bypassed by application of 5-hydroxy-L-tryptophan (5-HTP), neurons from both Tph2-/- and Sert-/- mice decreased their firing rates at significantly lower concentrations of 5-HTP compared to wildtype controls. Our findings demonstrate that, as opposed to the prevalent view, sensitivity of somatodendritic 5-HT1A receptors does not predict the magnitude of 5-HT neuron autoinhibition. Changes in 5-HT1A receptor sensitivity may rather be seen as an adaptive mechanism to keep autoinhibition functioning in response to extremely altered levels of extracellular 5-HT resulting from targeted inactivation of mediators of serotonergic signaling.},
  language  = {en}
}
@article{StrekalovaVeniaminovaSvirinetal.2021,
  author    = {Strekalova, Tatyana and Veniaminova, Ekaterina and Svirin, Evgeniy and Kopeikina, Ekaterina and Veremeyko, Tatyana and Yung, Amanda W. Y. and Proshin, Andrey and Tan, Shawn Zheng Kai and Khairuddin, Sharafuddin and Lim, Lee Wei and Lesch, Klaus-Peter and Walitza, Susanne and Anthony, Daniel C. and Ponomarev, Eugene D.},
  title     = {Sex-specific ADHD-like behaviour, altered metabolic functions, and altered EEG activity in sialyltransferase ST3GAL5-deficient mice},
  series = {Biomolecules},
  volume    = {11},
  journal   = {Biomolecules},
  number    = {12},
  issn      = {2218-273X},
  doi       = {10.3390/biom11121759},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-250071},
  year      = {2021},
  abstract  = {A deficiency in GM3-derived gangliosides, resulting from a lack of lactosylceramide-alpha-2,3-sialyltransferase (ST3GAL5), leads to severe neuropathology, including epilepsy and metabolic abnormalities. Disruption of ganglioside production by this enzyme may also have a role in the development of neuropsychiatric disorders. ST3Gal5 knock-out (St3gal5\(^{-/-}\)) mice lack a-, b-, and c-series gangliosides, but exhibit no overt neuropathology, possibly owing to the production of compensatory 0-series glycosphingolipids. Here, we sought to investigate the possibility that St3gal5\(^{-/-}\) mice might exhibit attention-deficit/hyperactivity disorder (ADHD)-like behaviours. In addition, we evaluated potential metabolic and electroencephalogram (EEG) abnormalities. St3gal5\(^{-/-}\) mice were subjected to behavioural testing, glucose tolerance tests, and the levels of expression of brain and peripheral A and B isoforms of the insulin receptor (IR) were measured. We found that St3gal5\(^{-/-}\) mice exhibit locomotor hyperactivity, impulsivity, neophobia, and anxiety-like behavior. The genotype also altered blood glucose levels and glucose tolerance. A sex bias was consistently found in relation to body mass and peripheral IR expression. Analysis of the EEG revealed an increase in amplitude in St3gal5\(^{-/-}\) mice. Together, St3gal5\(^{-/-}\) mice exhibit ADHD-like behaviours, altered metabolic and EEG measures providing a useful platform for better understanding of the contribution of brain gangliosides to ADHD and associated comorbidities.},
  language  = {en}
}
@article{SvirinVeniaminovaCostaNunesetal.2022,
  author    = {Svirin, Evgeniy and Veniaminova, Ekaterina and Costa-Nunes, Jo{\~a}o Pedro and Gorlova, Anna and Umriukhin, Aleksei and Kalueff, Allan V. and Proshin, Andrey and Anthony, Daniel C. and Nedorubov, Andrey and Tse, Anna Chung Kwan and Walitza, Susanne and Lim, Lee Wei and Lesch, Klaus-Peter and Strekalova, Tatyana},
  title     = {Predation stress causes excessive aggression in female mice with partial genetic inactivation of tryptophan hydroxylase-2: evidence for altered myelination-related processes},
  series = {Cells},
  volume    = {11},
  journal   = {Cells},
  number    = {6},
  issn      = {2073-4409},
  doi       = {10.3390/cells11061036},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-267250},
  year      = {2022},
  abstract  = {The interaction between brain serotonin (5-HT) deficiency and environmental adversity may predispose females to excessive aggression. Specifically, complete inactivation of the gene encoding tryptophan hydroxylase-2 (Tph2) results in the absence of neuronal 5-HT synthesis and excessive aggressiveness in both male and female null mutant (Tph2\(^{-/-}\)) mice. In heterozygous male mice (Tph2\(^{+/-}\)), there is a moderate reduction in brain 5-HT levels, and when they are exposed to stress, they exhibit increased aggression. Here, we exposed female Tph2\(^{+/-}\) mice to a five-day rat predation stress paradigm and assessed their emotionality and social interaction/aggression-like behaviors. Tph2\(^{+/-}\) females exhibited excessive aggression and increased dominant behavior. Stressed mutants displayed altered gene expression of the 5-HT receptors Htr1a and Htr2a, glycogen synthase kinase-3 β (GSK-3β), and c-fos as well as myelination-related transcripts in the prefrontal cortex: myelin basic protein (Mbp), proteolipid protein 1 (Plp1), myelin-associated glycoprotein (Mag), and myelin oligodendrocyte glycoprotein (Mog). The expression of the plasticity markers synaptophysin (Syp) and cAMP response element binding protein (Creb), but not AMPA receptor subunit A2 (GluA2), were affected by genotype. Moreover, in a separate experiment, na{\"i}ve female Tph2\(^{+/-}\) mice showed signs of enhanced stress resilience in the modified swim test with repeated swimming sessions. Taken together, the combination of a moderate reduction in brain 5-HT with environmental challenges results in behavioral changes in female mice that resemble the aggression-related behavior and resilience seen in stressed male mutants; additionally, the combination is comparable to the phenotype of null mutants lacking neuronal 5-HT. Changes in myelination-associated processes are suspected to underpin the molecular mechanisms leading to aggressive behavior.},
  language  = {en}
}
@article{GrimmWeberKittelSchneideretal.2020,
  author    = {Grimm, Oliver and Weber, Heike and Kittel-Schneider, Sarah and Kranz, Thorsten M. and Jacob, Christian P. and Lesch, Klaus-Peter and Reif, Andreas},
  title     = {Impulsivity and Venturesomeness in an Adult ADHD Sample: Relation to Personality, Comorbidity, and Polygenic Risk},
  series = {Frontiers in Psychiatry},
  volume    = {11},
  journal   = {Frontiers in Psychiatry},
  issn      = {1664-0640},
  doi       = {10.3389/fpsyt.2020.557160},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-219751},
  year      = {2020},
  abstract  = {While impulsivity is a basic feature of attention-deficit/hyperactivity disorder (ADHD), no study explored the effect of different components of the Impulsiveness (Imp) and Venturesomeness (Vent) scale (IV7) on psychiatric comorbidities and an ADHD polygenic risk score (PRS). We used the IV7 self-report scale in an adult ADHD sample of 903 patients, 70\% suffering from additional comorbid disorders, and in a subsample of 435 genotyped patients. Venturesomeness, unlike immediate Impulsivity, is not specific to ADHD. We consequently analyzed the influence of Imp and Vent also in the context of a PRS on psychiatric comorbidities of ADHD. Vent shows a distinctly different distribution of comorbidities, e.g., less anxiety and depression. PRS showed no effect on different ADHD comorbidities, but correlated with childhood hyperactivity. In a complementary analysis using principal component analysis with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition ADHD criteria, revised NEO Personality Inventory, Imp, Vent, and PRS, we identified three ADHD subtypes. These are an impulsive-neurotic type, an adventurous-hyperactive type with a stronger genetic component, and an anxious-inattentive type. Our study thus suggests the importance of adventurousness and the differential consideration of impulsivity in ADHD. The genetic risk is distributed differently between these subtypes, which underlines the importance of clinically motivated subtyping. Impulsivity subtyping might give insights into the organization of comorbid disorders in ADHD and different genetic background.},
  language  = {en}
}
@article{WaiderPoppMlinaretal.2019,
  author    = {Waider, Jonas and Popp, Sandy and Mlinar, Boris and Montalbano, Alberto and Bonfiglio, Francesco and Aboagye, Benjamin and Thuy, Elisabeth and Kern, Raphael and Thiel, Christopher and Araragi, Naozumi and Svirin, Evgeniy and Schmitt-B{\"o}hrer, Angelika G. and Corradetti, Renato and Lowry, Christopher A. and Lesch, Klaus-Peter},
  title     = {Serotonin deficiency increases context-dependent fear learning through modulation of hippocampal activity},
  series = {Frontiers in Neuroscience},
  volume    = {13},
  journal   = {Frontiers in Neuroscience},
  number    = {245},
  issn      = {1662-453X},
  doi       = {10.3389/fnins.2019.00245},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-196077},
  year      = {2019},
  abstract  = {Brain serotonin (5-hydroxytryptamine, 5-HT) system dysfunction is implicated in exaggerated fear responses triggering various anxiety-, stress-, and trauma-related disorders. However, the underlying mechanisms are not well understood. Here, we investigated the impact of constitutively inactivated 5-HT synthesis on context-dependent fear learning and extinction using tryptophan hydroxylase 2 (Tph2) knockout mice. Fear conditioning and context-dependent fear memory extinction paradigms were combined with c-Fos imaging and electrophysiological recordings in the dorsal hippocampus (dHip). Tph2 mutant mice, completely devoid of 5-HT synthesis in brain, displayed accelerated fear memory formation and increased locomotor responses to foot shock. Furthermore, recall of context-dependent fear memory was increased. The behavioral responses were associated with increased c-Fos expression in the dHip and resistance to foot shock-induced impairment of hippocampal long-term potentiation (LTP). In conclusion, increased context-dependent fear memory resulting from brain 5-HT deficiency involves dysfunction of the hippocampal circuitry controlling contextual representation of fear-related behavioral responses.},
  language  = {en}
}
@article{ClineCostaNunesCespuglioetal.2015,
  author    = {Cline, Brandon H. and Costa-Nunes, Joao P. and Cespuglio, Raymond and Markova, Natalyia and Santos, Ana I. and Bukhman, Yury V. and Kubatiev, Aslan and Steinbusch, Harry W. M. and Lesch, Klaus-Peter and Strekalova, Tatyana},
  title     = {Dicholine succinate, the neuronal insulin sensitizer, normalizes behavior, REM sleep, hippocampal pGSK3 beta and mRNAs of NMDA receptor subunits in mouse models of depression},
  series = {Frontiers in Behavioral Neuroscience},
  volume    = {9},
  journal   = {Frontiers in Behavioral Neuroscience},
  number    = {37},
  doi       = {10.3389/fnbeh.2015.00037},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-143992},
  year      = {2015},
  abstract  = {Central insulin receptor-mediated signaling is attracting the growing attention of researchers because of rapidly accumulating evidence implicating it in the mechanisms of plasticity, stress response, and neuropsychiatric disorders including depression. Dicholine succinate (DS), a mitochondrial complex II substrate, was shown to enhance insulin-receptor mediated signaling in neurons and is regarded as a sensitizer of the neuronal insulin receptor. Compounds enhancing neuronal insulin receptor-mediated transmission exert an antidepressant-like effect in several pre-clinical paradigms of depression; similarly, such properties for DS were found with a stress-induced anhedonia model. Here, we additionally studied the effects of DS on several variables which were ameliorated by other insulin receptor sensitizers in mice. Pre-treatment with DS of chronically stressed C57BL6 mice rescued normal contextual fear conditioning, hippocampal gene expression of NMDA receptor subunit NR2A, the NR2A/NR2B ratio and increased REM sleep rebound after acute predation. In 18-month-old C57BL6 mice, a model of elderly depression, DS restored normal sucrose preference and activated the expression of neural plasticity factors in the hippocampus as shown by Illumina microarray. Finally, young naive DS-treated C57BL6 mice had reduced depressive- and anxiety-like behaviors and, similarly to imipramine-treated mice, preserved hippocampal levels of the phosphorylated (inactive) form of GSK3 beta that was lowered by forced swimming in pharmacologically naive animals. Thus, DS can ameliorate behavioral and molecular outcomes under a variety of stress- and depression-related conditions. This further highlights neuronal insulin signaling as a new factor of pathogenesis and a potential pharmacotherapy of affective pathologies.},
  language  = {en}
}
@article{JuhaszGondaHullametal.2015,
  author    = {Juhasz, Gabriella and Gonda, Xenia and Hullam, Gabor and Eszlari, Nora and Kovacs, David and Lazary, Judit and Pap, Dorottya and Petschner, Peter and Elliott, Rebecca and Deakin, John Francis William and Muir Anderson, Ian and Antal, Peter and Lesch, Klaus-Peter and Bagdy, Gyorgy},
  title     = {Variability in the effect of 5-HTTLPR on depression in a large European population: the role of age, symptom profile, type and intensity of life stressors},
  series = {PLoS ONE},
  volume    = {10},
  journal   = {PLoS ONE},
  number    = {3},
  doi       = {10.1371/journal.pone.0116316},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-143703},
  pages     = {e0116316},
  year      = {2015},
  abstract  = {Background Although 5-HTTLPR has been shown to influence the risk of life stress-induced depression in the majority of studies, others have produced contradictory results, possibly due to weak effects and/or sample heterogeneity. Methods In the present study we investigated how age, type and intensity of life-stressors modulate the effect of 5-HTTLPR on depression and anxiety in a European population cohort of over 2300 subjects. Recent negative life events (RLE), childhood adversity (CHA), lifetime depression, Brief Symptoms Inventory (BSI) depression and anxiety scores were determined in each subject. Besides traditional statistical analysis we calculated Bayesian effect strength and relevance of 5-HTTLPR genotypes in specified models. Results The short (s) low expressing allele showed association with increased risk of depression related phenotypes, but all nominally significant effects would turn to non-significant after correction for multiple testing in the traditional analysis. Bayesian effect strength and relevance analysis, however, confirmed the role of 5-HTTLPR. Regarding current (BSI) and lifetime depression 5-HTTLPR-by-RLE interactions were confirmed. Main effect, with other words direct association, was supported with BSI anxiety. With more frequent RLE the prevalence or symptoms of depression increased in ss carriers. Although CHA failed to show an interaction with 5-HTTLPR, in young subjects CHA sensitized towards the depression promoting effect of even mild RLE. Furthermore, the direct association of anxiety with the s allele was driven by young (\(\leq\)30) individuals. Limitations Our study is cross-sectional and applies self-report questionnaires. Conclusions Albeit 5-HTTLPR has only weak/moderate effects, the s allele is directly associated with anxiety and modulates development of depression in homogeneous subgroups.},
  language  = {en}
}
@article{BoddenRichterSchreiberetal.2015,
  author    = {Bodden, Carina and Richter, S. Helene and Schreiber, Rebecca S. and Kloke, Vanessa and Gerß, Joachim and Palme, Rupert and Lesch, Klaus-Peter and Lewejohann, Lars and Kaiser, Sylvia and Sachser, Norbert},
  title     = {Benefits of adversity?! How life history affects the behavioral profile of mice varying in serotonin transporter genotype},
  series = {Frontiers in Behavioral Neuroscience},
  volume    = {9},
  journal   = {Frontiers in Behavioral Neuroscience},
  number    = {47},
  doi       = {10.3389/fnbeh.2015.00047},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-143723},
  year      = {2015},
  abstract  = {Behavioral profiles are influenced by both positive and negative experiences as well as the genetic disposition. Traditionally, accumulating adversity over lifetime is considered to predict increased anxiety like behavior ("allostatic load"). The alternative "mismatch hypothesis" suggests increased levels of anxiety if the early environment differs from the later-life environment. Thus, there is a need for a whole-life history approach to gain a deeper understanding of how behavioral profiles are shaped. The aim of this study was to elucidate the effects of life history on the behavioral profile of mice varying in serotonin transporter (5-HIT) genotype, an established mouse model of increased anxiety-like behavior. For this purpose, mice grew up under either adverse or beneficial conditions during early phases of life. In adulthood, they were further subdivided so as to face a situation that either matched or mismatched the condition experienced so far, resulting in four different life histories. Subsequently, mice were tested for their anxiety-like and exploratory behavior. The main results were: (1) Life history profoundly modulated the behavioral profile. Surprisingly, mice that experienced early beneficial and later escapable adverse conditions showed less anxiety-like and more exploratory behavior compared to mice of other life histories. (2) Genotype significantly influenced the behavioral profile, with homozygous 5-HTT knockout mice displaying highest levels of anxiety-like and lowest levels of exploratory behavior. Our findings concerning life history indicate that the absence of adversity does not necessarily cause lower levels of anxiety than accumulating adversity. Rather, some adversity may be beneficial, particularly when following positive events. Altogether, we conclude that for an understanding of behavioral profiles, it is not sufficient to look at experiences during single phases of life, but the whole life history has to be considered.},
  language  = {en}
}
@article{StrekalovaPavlovTrofimovetal.2022,
  author    = {Strekalova, Tatyana and Pavlov, Dmitrii and Trofimov, Alexander and Anthony, Daniel C. and Svistunov, Andrei and Proshin, Andrey and Umriukhin, Aleksei and Lyundup, Alexei and Lesch, Klaus-Peter and Cespuglio, Raymond},
  title     = {Hippocampal over-expression of cyclooxygenase-2 (COX-2) is associated with susceptibility to stress-induced anhedonia in mice},
  series = {International Journal of Molecular Sciences},
  volume    = {23},
  journal   = {International Journal of Molecular Sciences},
  number    = {4},
  issn      = {1422-0067},
  doi       = {10.3390/ijms23042061},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-284056},
  year      = {2022},
  abstract  = {The phenomenon of individual variability in susceptibility/resilience to stress and depression, in which the hippocampus plays a pivotal role, is attracting increasing attention. We investigated the potential role of hippocampal cyclooxygenase-2 (COX-2), which regulates plasticity, neuroimmune function, and stress responses that are all linked to this risk dichotomy. We used a four-week-long chronic mild stress (CMS) paradigm, in which mice could be stratified according to their susceptibility/resilience to anhedonia, a key feature of depression, to investigate hippocampal expression of COX-2, a marker of microglial activation Iba-1, and the proliferation marker Ki67. Rat exposure, social defeat, restraints, and tail suspension were used as stressors. We compared the effects of treatment with either the selective COX-2 inhibitor celecoxib (30 mg/kg/day) or citalopram (15 mg/kg/day). For the celecoxib and vehicle-treated mice, the Porsolt test was used. Anhedonic (susceptible) but not non-anhedonic (resilient) animals exhibited elevated COX-2 mRNA levels, increased numbers of COX-2 and Iba-1-positive cells in the dentate gyrus and the CA1 area, and decreased numbers of Ki67-positive cells in the subgranular zone of the hippocampus. Drug treatment decreased the percentage of anhedonic mice, normalized swimming activity, reduced behavioral despair, and improved conditioned fear memory. Hippocampal over-expression of COX-2 is associated with susceptibility to stress-induced anhedonia, and its pharmacological inhibition with celecoxib has antidepressant effects that are similar in size to those of citalopram.},
  language  = {en}
}
@article{FernandezCastilloCabanaDominguezKappeletal.2021,
  author    = {Fern{\`a}ndez-Castillo, No{\`e}lia and Cabana-Dom{\´i}nguez, Judit and Kappel, Djenifer B. and Torrico, B{\`a}rbara and Weber, Heike and Lesch, Klaus-Peter and Lao, Oscar and Reif, Andreas and Cormand, Bru},
  title     = {Exploring the contribution to ADHD of genes involved in Mendelian disorders presenting with hyperactivity and/or inattention},
  series = {Genes},
  volume    = {13},
  journal   = {Genes},
  number    = {1},
  issn      = {2073-4425},
  doi       = {10.3390/genes13010093},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-252346},
  year      = {2021},
  abstract  = {Attention-deficit hyperactivity disorder (ADHD) is a complex neurodevelopmental disorder characterized by hyperactivity, impulsivity, and/or inattention, which are symptoms also observed in many rare genetic disorders. We searched for genes involved in Mendelian disorders presenting with ADHD symptoms in the Online Mendelian Inheritance in Man (OMIM) database, to curate a list of new candidate risk genes for ADHD. We explored the enrichment of functions and pathways in this gene list, and tested whether rare or common variants in these genes are associated with ADHD or with its comorbidities. We identified 139 genes, causal for 137 rare disorders, mainly related to neurodevelopmental and brain function. Most of these Mendelian disorders also present with other psychiatric traits that are often comorbid with ADHD. Using whole exome sequencing (WES) data from 668 ADHD cases, we found rare variants associated with the dimension of the severity of inattention symptoms in three genes: KIF11, WAC, and CRBN. Then, we focused on common variants and identified six genes associated with ADHD (in 19,099 cases and 34,194 controls): MANBA, UQCC2, HIVEP2, FOPX1, KANSL1, and AUH. Furthermore, HIVEP2, FOXP1, and KANSL1 were nominally associated with autism spectrum disorder (ASD) (18,382 cases and 27,969 controls), as well as HIVEP2 with anxiety (7016 cases and 14,475 controls), and FOXP1 with aggression (18,988 individuals), which is in line with the symptomatology of the rare disorders they are responsible for. In conclusion, inspecting Mendelian disorders and the genes responsible for them constitutes a valuable approach for identifying new risk genes and the mechanisms of complex disorders.},
  language  = {en}
}