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The transport of glucose across the cell plasma membrane is vital to most mammalian cells. The glucose transporter (GLUT; also called SLC2A) family of transmembrane solute carriers is responsible for this function in vivo. GLUT proteins encompass 14 different isoforms in humans with different cell type-specific expression patterns and activities. Central to glucose utilization and delivery in the brain is the neuronally expressed GLUT3. Recent research has shown an involvement of GLUT3 genetic variation or altered expression in several different brain disorders, including Huntington’s and Alzheimer’s diseases. Furthermore, GLUT3 was identified as a potential risk gene for multiple psychiatric disorders. To study the role of GLUT3 in brain function and disease a more detailed knowledge of its expression in model organisms is needed. Zebrafish (Danio rerio) has in recent years gained popularity as a model organism for brain research and is now well-established for modeling psychiatric disorders. Here, we have analyzed the sequence of GLUT3 orthologs and identified two paralogous genes in the zebrafish, slc2a3a and slc2a3b. Interestingly, the Glut3b protein sequence contains a unique stretch of amino acids, which may be important for functional regulation. The slc2a3a transcript is detectable in the central nervous system including distinct cellular populations in telencephalon, diencephalon, mesencephalon and rhombencephalon at embryonic and larval stages. Conversely, the slc2a3b transcript shows a rather diffuse expression pattern at different embryonic stages and brain regions. Expression of slc2a3a is maintained in the adult brain and is found in the telencephalon, diencephalon, mesencephalon, cerebellum and medulla oblongata. The slc2a3b transcripts are present in overlapping as well as distinct regions compared to slc2a3a. Double in situ hybridizations were used to demonstrate that slc2a3a is expressed by some GABAergic neurons at embryonic stages. This detailed description of zebrafish slc2a3a and slc2a3b expression at developmental and adult stages paves the way for further investigations of normal GLUT3 function and its role in brain disorders.
Patients with panic and post-traumatic stress disorders seem to show increased psychophysiological reactions to conditions of unpredictable (U) threat, which has been discussed as a neurobiological marker of elevated levels of sustained fear in these disorders. Interestingly, a recent study found that the right inferior frontal gyrus (rIFG) is correlated to the successful regulation of sustained fear during U threat. Therefore this study aimed to examine the potential use of non-invasive brain stimulation to foster the rIFG by means of anodal transcranial direct current stimulation (tDCS) in order to reduce psychophysiological reactions to U threat. Twenty six participants were randomly assigned into an anodal and sham stimulation group in a double-blinded manner. Anodal and cathodal electrodes (7 * 5 cm) were positioned right frontal to target the rIFG. Stimulation intensity was I = 2 mA applied for 20 min during a task including U threat conditions (NPU-task). The effects of the NPU paradigm were measured by assessing the emotional startle modulation and the skin conductance response (SCR) at the outset of the different conditions. We found a significant interaction effect of condition × tDCS for the SCR (F(2,48) = 6.3, p < 0.01) without main effects of condition and tDCS. Post hoc tests revealed that the increase in SCR from neutral (N) to U condition was significantly reduced in verum compared to the sham tDCS group (t(24) = 3.84, p < 0.001). Our results emphasize the causal role of rIFG for emotional regulation and the potential use of tDCS to reduce apprehension during U threat conditions and therefore as a treatment for anxiety disorders.
Spin-lock based functional magnetic resonance imaging (fMRI) has the potential for direct spatially-resolved detection of neuronal activity and thus may represent an important step for basic research in neuroscience. In this work, the corresponding fundamental effect of Rotary EXcitation (REX) is investigated both in simulations as well as in phantom and in vivo experiments. An empirical law for predicting optimal spin-lock pulse durations for maximum magnetic field sensitivity was found. Experimental conditions were established that allow robust detection of ultra-weak magnetic field oscillations with simultaneous compensation of static field inhomogeneities. Furthermore, this work presents a novel concept for the emulation of brain activity utilizing the built-in MRI gradient system, which allows REX sequences to be validated in vivo under controlled and reproducible conditions. Via transmission of Rotary EXcitation (tREX), we successfully detected magnetic field oscillations in the lower nano-Tesla range in brain tissue. Moreover, tREX paves the way for the quantification of biomagnetic fields.
Punishment feels bad, but relief upon its termination feels good. As a consequence of such timing-dependent valence reversal, memories of opposite valence can result from associating stimulus A with, for example, the occurrence of punishment (A-) versus punishment termination (-A): A- training results in aversive memory, but -A training in appetitive memory (corresponding effects exist for reward occurrence and termination). Whereas learning through the occurrence of punishment is well studied, much less is known about learning through its termination. Current research investigates how dopaminergic system function contributes to these processes in Drosophila, rats and humans. We argue that dopamine-related psychopathology may entail distortions in learning through punishment termination, and that this may contribute, for example, to non-suicidal self-injury or post-traumatic stress disorder.
The negative societal impacts associated with the increasing prevalence of violence and aggression is increasing, and, with this rise, is the need to understand the molecular and cellular changes that underpin ultrasound-induced aggressive behavior. In mice, stress-induced aggression is known to alter AMPA receptor subunit expression, plasticity markers, and oxidative stress within the brain. Here, we induced aggression in BALB/c mice using chronic ultrasound exposure and examined the impact of the psychoactive anti-oxidant compounds thiamine (vitamin B1), and its derivative benfotiamine, on AMPA receptor subunit expression, established plasticity markers, and oxidative stress. The administration of thiamine or benfotiamine (200 mg/kg/day) in drinking water decreased aggressive behavior following 3-weeks of ultrasound exposure and benfotiamine, reduced floating behavior in the swim test. The vehicle-treated ultrasound-exposed mice exhibited increases in protein carbonyl and total glutathione, altered AMPA receptor subunits expression, and decreased expression of plasticity markers. These ultrasound-induced effects were ameliorated by thiamine and benfotiamine treatment; in particular both antioxidants were able to reverse ultrasound-induced changes in GluA1 and GluA2 subunit expression, and, within the prefrontal cortex, significantly reversed the changes in protein carbonyl and polysialylated form of neural cell adhesion molecule (PSA-NCAM) expression levels. Benfotiamine was usually more efficacious than thiamine. Thus, the thiamine compounds were able to counteract ultrasound-induced aggression, which was accompanied by the normalization of markers that have been showed to be associated with ultrasound-induced aggression. These commonly used, orally-active compounds may have considerable potential for use in the control of aggression within the community.
This article is part of the Special Issue entitled ‘Current status of the neurobiology of aggression and impulsivity’.
Risperidone is commonly used to treat different psychiatric disorders worldwide. Knowledge on dose–concentration relationships of risperidone treatment in children and adolescents with schizophrenia or other psychotic disorders is, however, scarce and no age-specific therapeutic ranges have been established yet. Multicenter data of a therapeutic drug monitoring service were analyzed to evaluate the relationship between risperidone dose and serum concentration of the active moiety (risperidone (RIS) plus its main metabolite 9-hydroxyrisperidone (9-OH-RIS)) in children and adolescents with psychotic disorders. Patient characteristics, doses, serum concentrations and therapeutic outcomes were assessed by standardized measures. The study also aimed to evaluate whether the therapeutic reference range for adults (20–60 ng/ml) is applicable for minors. In the 64 patients (aged 11–18 years) included, a positive correlation between daily dose and the active moiety (RIS\(_{am}\)) concentration was found (r\(_s\) = 0.49, p = 0.001) with variation in dose explaining 24% (r\(_s\)\(^2\) = 0.240) of the variability in serum concentrations. While the RIS\(_{am}\) concentration showed no difference, RIS as well 9-OH-RIS concentrations and the parent to metabolite ratio varied significantly in patients with co-medication of a CYP2D6 inhibitor. Patients with extrapyramidal symptoms (EPS) had on average higher RIS\(_{am}\) concentrations than patients without (p = 0.05). Considering EPS, the upper threshold of the therapeutic range of RIS\(_{am}\) was determined to be 33 ng/ml. A rough estimation method also indicated a possibly decreased lower limit of the preliminary therapeutic range in minors compared to adults. These preliminary data may contribute to the definition of a therapeutic window in children and adolescents with schizophrenic disorders treated with risperidone. TDM is recommended in this vulnerable population to prevent concentration-related adverse drug reactions.
Objectives
Embedded in the Collaborative Research Center “Fear, Anxiety, Anxiety Disorders” (CRC‐TRR58), this bicentric clinical study aims at identifying biobehavioral markers of treatment (non‐)response by applying machine learning methodology with an external cross‐validation protocol. We hypothesize that a priori prediction of treatment (non‐)response is possible in a second, independent sample based on multimodal markers.
Methods
One‐session virtual reality exposure treatment (VRET) with patients with spider phobia was conducted on two sites. Clinical, neuroimaging, and genetic data were assessed at baseline, post‐treatment and after 6 months. The primary and secondary outcomes defining treatment response are as follows: 30% reduction regarding the individual score in the Spider Phobia Questionnaire and 50% reduction regarding the individual distance in the behavioral avoidance test.
Results
N = 204 patients have been included (n = 100 in Würzburg, n = 104 in Münster). Sample characteristics for both sites are comparable.
Discussion
This study will offer cross‐validated theranostic markers for predicting the individual success of exposure‐based therapy. Findings will support clinical decision‐making on personalized therapy, bridge the gap between basic and clinical research, and bring stratified therapy into reach. The study is registered at ClinicalTrials.gov (ID: NCT03208400).
Anxiety and aggression are part of the behavioral repertoire of humans and animals. However, in their exaggerated form both can become maladaptive and result in psychiatric disorders. On the one hand, genetic predisposition has been shown to play a crucial modulatory role in anxiety and aggression. On the other hand, social experiences have been implicated in the modulation of these traits. However, so far, mainly experiences in early life phases have been considered crucial for shaping anxiety-like and aggressive behavior, while the phase of adolescence has largely been neglected. Therefore, the aim of the present study was to elucidate how levels of anxiety-like and aggressive behavior are shaped by social experiences during adolescence and serotonin transporter (5-HTT) genotype. For this purpose, male mice of a 5-HTT knockout mouse model including all three genotypes (wildtype, heterozygous and homozygous 5-HTT knockout mice) were either exposed to an adverse social situation or a beneficial social environment during adolescence. This was accomplished in a custom-made cage system where mice experiencing the adverse environment were repeatedly introduced to the territory of a dominant opponent but had the possibility to escape to a refuge cage. Mice encountering beneficial social conditions had free access to a female mating partner. Afterwards, anxiety-like and aggressive behavior was assessed in a battery of tests. Surprisingly, unfavorable conditions during adolescence led to a decrease in anxiety-like behavior and an increase in exploratory locomotion. Additionally, aggressive behavior was augmented in animals that experienced social adversity. Concerning genotype, homozygous 5-HTT knockout mice were more anxious and less aggressive than heterozygous 5-HTT knockout and wildtype mice. In summary, adolescence is clearly an important phase in which anxiety-like and aggressive behavior can be shaped. Furthermore, it seems that having to cope with challenge during adolescence instead of experiencing throughout beneficial social conditions leads to reduced levels of anxiety-like behavior.
Anxiety and depressive disorders result from a complex interplay of genetic and environmental factors and are common mutual comorbidities. On the level of cellular signaling, regulator of G protein signaling 2 (Rgs2) has been implicated in human and rodent anxiety as well as rodent depression. Rgs2 negatively regulates G protein-coupled receptor (GPCR) signaling by acting as a GTPase accelerating protein towards the Gα subunit.
The present study investigates, whether mice with a homozygous Rgs2 deletion (Rgs2-/-) show behavioral alterations as well as an increased susceptibility to stressful life events related to human anxiety and depressive disorders and tries to elucidate molecular underlying’s of these changes.
To this end, Rgs2-/- mice were characterized in an aversive-associative learning paradigm to evaluate learned fear as a model for the etiology of human anxiety disorders. Spatial learning and reward motivated spatial learning were evaluated to control for learning in non-aversive paradigms. Rgs2 deletion enhanced learning in all three paradigms, rendering increased learning upon deletion of Rgs2 not specific for aversive learning. These data support reports indicating increased long-term potentiation in Rgs2-/- mice and may predict treatment response to conditioning based behavior therapy in patients with polymorphisms associated with reduced RGS2 expression. Previous reports of increased innate anxiety were corroborated in three tests based on the approach-avoidance conflict. Interestingly, Rgs2-/- mice showed novelty-induced hypo-locomotion suggesting neophobia, which may translate to the clinical picture of agoraphobia in humans and reduced RGS2 expression in humans was associated with a higher incidence of panic disorder with agoraphobia. Depression-like behavior was more distinctive in female Rgs2-/- mice. Stress resilience, tested in an acute and a chronic stress paradigm, was also more distinctive in female Rgs2-/- mice, suggesting Rgs2 to contribute to sex specific effects of anxiety disorders and depression.
Rgs2 deletion was associated with GPCR expression changes of the adrenergic, serotonergic, dopaminergic and neuropeptide Y systems in the brain and heart as well as reduced monoaminergic neurotransmitter levels. Furthermore, the expression of two stress-related microRNAs was increased upon Rgs2 deletion. The aversive-associative learning paradigm induced a dynamic Rgs2 expression change. The observed molecular changes may contribute to the anxious and depressed phenotype as well as promote altered stress reactivity, while reflecting an alter basal stress level and a disrupted sympathetic tone. Dynamic Rgs2 expression may mediate changes in GPCR signaling duration during memory formation.
Taken together, Rgs2 deletion promotes increased anxiety-like and depression-like behavior, altered stress reactivity as well as increased cognitive function.
In 55 chronic schizophrenics, the occurrence of infectious diseases during their mothers' pregnancies was investigated. Different psychiatrie diagnostic systems were compared. Infections were reported by the mothers of familial and sporadic DSM I1I-R schizophrenics in equal proportion. However, applying Leonhard's classification, the frequency of infections was found to be significantly increased in 'systematic' schizophrenia (mainly exogenously induced in the view of Leonhard) compared to 'unsystematic' schizophrenia (mainly genetically determined according to Leonhard's findings). Most of the infections occurred during the second trimester (nine out of 13). Thus, in the 'systematic' forms of schizophrenia (low genetic loading), maternal infections in this crucial period of neurodevelopment would appear to be important causative factors in the cytoarchitectural deviance detected in the central nervous system of schizophrenics.