ABSTRACT
BACKGROUND: To characterize neurodevelopmental abnormalities in children up to 36 months of age with congenital Zika virus exposure. METHODS: From the U.S. Zika Pregnancy and Infant Registry, a national surveillance system to monitor pregnancies with laboratory evidence of Zika virus infection, pregnancy outcomes and presence of Zika associated birth defects (ZBD) were reported among infants with available information. Neurologic sequelae and developmental delay were reported among children with ≥1 follow-up exam after 14 days of age or with ≥1 visit with development reported, respectively. RESULTS: Among 2248 infants, 10.1% were born preterm, and 10.5% were small-for-gestational age. Overall, 122 (5.4%) had any ZBD; 91.8% of infants had brain abnormalities or microcephaly, 23.0% had eye abnormalities, and 14.8% had both. Of 1881 children ≥1 follow-up exam reported, neurologic sequelae were more common among children with ZBD (44.6%) vs. without ZBD (1.5%). Of children with ≥1 visit with development reported, 46.8% (51/109) of children with ZBD and 7.4% (129/1739) of children without ZBD had confirmed or possible developmental delay. CONCLUSION: Understanding the prevalence of developmental delays and healthcare needs of children with congenital Zika virus exposure can inform health systems and planning to ensure services are available for affected families. IMPACT: We characterize pregnancy and infant outcomes and describe neurodevelopmental abnormalities up to 36 months of age by presence of Zika associated birth defects (ZBD). Neurologic sequelae and developmental delays were common among children with ZBD. Children with ZBD had increased frequency of neurologic sequelae and developmental delay compared to children without ZBD. Longitudinal follow-up of infants with Zika virus exposure in utero is important to characterize neurodevelopmental delay not apparent in early infancy, but logistically challenging in surveillance models.
Subject(s)
Microcephaly , Neurodevelopmental Disorders , Pregnancy Complications, Infectious , Zika Virus Infection , Zika Virus , Infant , Infant, Newborn , Pregnancy , Child , Female , Humans , Child, Preschool , Zika Virus Infection/complications , Zika Virus Infection/epidemiology , Zika Virus Infection/congenital , Pregnancy Complications, Infectious/epidemiology , Microcephaly/epidemiology , Neurodevelopmental Disorders/complicationsABSTRACT
Stress-related psychiatric disorders such as depression are among the leading causes of morbidity and mortality. Considering that many individuals fail to respond to currently available antidepressant drugs, there is a need for antidepressants with novel mechanisms. Polymorphisms in the gene encoding FK506-binding protein 51 (FKBP51), a co-chaperone of the glucocorticoid receptor, have been linked to susceptibility to stress-related psychiatric disorders. Whether this protein can be targeted for their treatment remains largely unexplored. The aim of this work was to investigate whether inhibition of FKBP51 with SAFit2, a novel selective inhibitor, promotes hippocampal neuron outgrowth and neurogenesis in vitro and stress resilience in vivo in a mouse model of chronic psychosocial stress. Primary hippocampal neuronal cultures or hippocampal neural progenitor cells (NPCs) were treated with SAFit2 and neuronal differentiation and cell proliferation were analyzed. Male C57BL/6 mice were administered SAFit2 while concurrently undergoing a chronic stress paradigm comprising of intermittent social defeat and overcrowding, and anxiety and depressive -related behaviors were evaluated. SAFit2 increased neurite outgrowth and number of branch points to a greater extent than brain derived neurotrophic factor (BDNF) in primary hippocampal neuronal cultures. SAFit2 increased hippocampal NPC neurogenesis and increased neurite complexity and length of these differentiated neurons. In vivo, chronic SAFit2 administration prevented stress-induced social avoidance, decreased anxiety in the novelty-induced hypophagia test, and prevented stress-induced anxiety in the open field but did not alter adult hippocampal neurogenesis in stressed animals. These data warrant further exploration of inhibition of FKBP51 as a strategy to treat stress-related disorders.
Subject(s)
Hippocampus , Resilience, Psychological , Stress, Psychological , Tacrolimus Binding Proteins , Animals , Male , Mice , Antidepressive Agents/pharmacology , Brain-Derived Neurotrophic Factor/metabolism , Depression/drug therapy , Hippocampus/metabolism , Mice, Inbred C57BL , Neurogenesis/drug effects , Resilience, Psychological/drug effects , Stress, Psychological/metabolism , Tacrolimus Binding Proteins/antagonists & inhibitors , Tacrolimus Binding Proteins/metabolismABSTRACT
The 22q11.2 hemizygous deletion confers high risk for multiple neurodevelopmental disorders. Inhibitory signaling, largely regulated through GABAA receptors, is suggested to serve a multitude of brain functions that are disrupted in the 22q11.2 deletion syndrome. We investigated the putative deficit of GABAA receptors and the potential substrates contributing to the inhibitory and excitatory dysregulations in hippocampal networks of the Df(h22q11)/+ mouse model of the 22q11.2 hemizygous deletion. The Df(h22q11)/+ mice exhibited impairments in several hippocampus-related functional domains, represented by impaired spatial memory and sensory gating functions. Autoradiography using the [3H]muscimol tracer revealed a significant reduction in GABAA receptor binding in the CA1 and CA3 subregions, together with a loss of GAD67+ interneurons in CA1 of Df(h22q11)/+ mice. Furthermore, electrophysiology recordings exhibited significantly higher neuronal activity in CA3, in response to the GABAA receptor antagonist, bicuculline, as compared with wild type mice. Density and volume of dendritic spines in pyramidal neurons were reduced and Sholl analysis also showed a reduction in the complexity of basal dendritic tree in CA1 and CA3 subregions of Df(h22q11)/+ mice. Overall, our findings demonstrate that hemizygous deletion in the 22q11.2 locus leads to dysregulations in the inhibitory circuits, involving reduced binding levels of GABAA receptors, in addition to functional and structural modulations of the excitatory networks of hippocampus.
Subject(s)
Hippocampus , Receptors, GABA-A , Animals , Disease Models, Animal , Hippocampus/metabolism , Mice , Muscimol/metabolism , Muscimol/pharmacology , Pyramidal Cells/metabolism , Receptors, GABA-A/genetics , Receptors, GABA-A/metabolism , gamma-Aminobutyric Acid/metabolismABSTRACT
The antidepressant vortioxetine has high affinity for the ionotropic 5-HT3 receptor (5-HT3 R) as well as other targets including the 5-HT transporter. The procognitive effects of vortioxetine have been linked to altered excitatory:inhibitory balance in cortex. Thus, vortioxetine purportedly inhibits cortical 5-HT3 R-expressing interneurons (5-HT3 R-INs) to disinhibit excitatory pyramidal neurons. The current study determined for the first time the effect of vortioxetine on the in vivo firing of putative 5-HT3 R-INs whilst simultaneously recording pyramidal neuron activity using cortical slow-wave oscillations as a readout. Extracellular single unit and local field potential recordings were made in superficial layers of the prefrontal cortex of urethane-anaesthetised rats. 5-HT3 R-INs were identified by a short-latency excitation evoked by electrical stimulation of the dorsal raphe nucleus (DRN). Juxtacellular-labelling found such neurons had the morphological and immunohistochemical properties of 5-HT3 R-INs: basket cell or bipolar cell morphology, expression of 5-HT3 R-IN markers and parvalbumin-immunonegative. Vortioxetine inhibited the short-latency DRN-evoked excitation of 5-HT3 R-INs and simultaneously decreased cortical slow wave oscillations, indicative of pyramidal neuron activation. Likewise, the 5-HT3 R antagonist ondansetron inhibited the short-latency DRN-evoked excitation of 5-HT3 R-INs. However unlike vortioxetine, ondansetron did not decrease cortical slow-wave oscillations, suggesting a dissociation between this effect and inhibition of 5-HT3 R-INs. The 5-HT reuptake inhibitor escitalopram had no consistent effect on any electrophysiological parameter measured. Overall, the current findings suggest that vortioxetine simultaneously inhibits (DRN-evoked) 5-HT3 R-INs and excites pyramidal neurons, thereby changing the excitatory:inhibitory balance in cortex. However, under the current experimental conditions, these two effects were dissociable with only the former likely involving a 5-HT3 R-mediated mechanism.
Subject(s)
Ondansetron , Serotonin , Animals , Antidepressive Agents/pharmacology , Interneurons/metabolism , Piperazines/pharmacology , Rats , Serotonin/metabolism , Serotonin 5-HT3 Receptor Antagonists/pharmacology , Sulfides/pharmacology , Vortioxetine/pharmacologyABSTRACT
The 15q13.3 deletion is associated with multiple neurodevelopmental disorders including epilepsy, schizophrenia, and autism. The Df(h15q13)/+ mouse model was recently generated that recapitulates several phenotypic features of the human 15q13.3 deletion syndrome (DS). However, the biological substrates underlying these phenotypes in Df(h15q13)/+ mice have not yet been fully characterized. RNA sequencing followed by real-time quantitative PCR, western blotting, liquid chromatography-mass spectrometry, and stereological analysis were employed to dissect the molecular, structural, and neurochemical phenotypes of the medial prefrontal cortex (mPFC) circuits in Df(h15q13)/+ mouse model. Transcriptomic profiling revealed enrichment for astrocyte-specific genes among differentially expressed genes, translated by a decrease in the number of glial fibrillary acidic protein positive cells in mPFC of Df(h15q13)/+ mice compared with wild-type mice. mPFC in Df(h15q13)/+ mice also showed a deficit of the inhibitory presynaptic marker GAD65, in addition to a reduction in dendritic arborization and spine density of pyramidal neurons from layers II/III. mPFC levels of GABA and glutamate neurotransmitters were not different between genotypes. Our results suggest that the 15q13.3 deletion modulates nonneuronal circuits in mPFC and confers molecular and morphometric alterations in the inhibitory and excitatory neurocircuits, respectively. These alterations potentially contribute to the phenotypes accompanied with the 15q13.3DS.
Subject(s)
Astrocytes/pathology , Chromosome Disorders/pathology , Chromosome Disorders/physiopathology , Intellectual Disability/pathology , Intellectual Disability/physiopathology , Prefrontal Cortex/pathology , Prefrontal Cortex/physiopathology , Seizures/pathology , Seizures/physiopathology , Synapses/pathology , Animals , Chromosome Deletion , Chromosomes, Human, Pair 15 , Disease Models, Animal , Male , MiceABSTRACT
A significant number of patients (30%) do not adequately respond to commonly prescribed antidepressants (e.g. SSRIs, SNRIs, and TCAs). Opioid receptors and their endogenous peptides have demonstrated a clear role in the regulation of mood in animal models and may offer an alternative approach to augment existing therapies. Nevertheless, there is an urgent need to find better ways to predict a patient's response to drug treatment, to improve overall drug responding, and to reduce the time to symptom remission using novel diagnostic and efficacy biomarkers. Cognitive processes, such as perception, attention, memory, and learning, are impaired in patients with mood disorders. These processes can be altered by emotions, a phenomenon called cognitive affective bias. Negative affective biases are a key feature of major depressive disorder (MDD) and may present concurrently with other cognitive deficits. Importantly, a significant percentage of patients report residual cognitive impairments even after effective drug treatment. This approach offers a new opportunity to predict patient treatment responses, potentially improving residual cognitive symptoms and patient outcomes. This review will (1) describe the underlying neurocircuitry of affective cognition and propose how negative biases may occur, (2) outline the role of opioid receptors in affective cognition, executive function, and MDD, and (3) present evidence from the published literature supporting a modulatory role for opioid drugs on negative affective bias, with a focus on kappa-opioid receptor antagonists, currently in development for clinical use for treatment-resistant MDD.
Subject(s)
Analgesics, Opioid/pharmacology , Cognition/drug effects , Mood Disorders/drug therapy , Affect/drug effects , Affective Symptoms/drug therapy , Analgesics, Opioid/metabolism , Antidepressive Agents/pharmacology , Attention/physiology , Bias , Cognition Disorders/drug therapy , Cognitive Dysfunction/drug therapy , Depressive Disorder, Major/drug therapy , Emotions/physiology , Executive Function , Humans , Learning , Memory/physiology , Mood Disorders/physiopathology , Neuropsychological Tests , Selective Serotonin Reuptake Inhibitors/pharmacology , Serotonin and Noradrenaline Reuptake Inhibitors/pharmacologyABSTRACT
Background: Preclinical studies have indicated that antidepressant effect of vortioxetine involves increased synaptic plasticity and promotion of spine maturation. Mitochondria dysfunction may contribute to the pathophysiological basis of major depressive disorder. Taking into consideration that vortioxetine increases spine number and dendritic branching in hippocampus CA1 faster than fluoxetine, we hypothesize that new spines induced by vortioxetine can rapidly form functional synapses by mitochondrial support, accompanied by increased brain-derived neurotrophic factor signaling. Methods: Rats were treated for 1 week with vortioxetine or fluoxetine at pharmacologically relevant doses. Number of synapses and mitochondria in hippocampus CA1 were quantified by electron microscopy. Brain-derived neurotrophic factor protein levels were visualized with immunohistochemistry. Gene and protein expression of synapse and mitochondria-related markers were investigated with real-time quantitative polymerase chain reaction and immunoblotting. Results: Vortioxetine increased number of synapses and mitochondria significantly, whereas fluoxetine had no effect after 1-week dosing. BDNF levels in hippocampus DG and CA1 were significantly higher after vortioxetine treatment. Gene expression levels of Rac1 after vortioxetine treatment were significantly increased. There was a tendency towards increased gene expression levels of Drp1 and protein levels of Rac1. However, both gene and protein levels of c-Fos were significantly decreased. Furthermore, there was a significant positive correlation between BDNF levels and mitochondria and synapse numbers. Conclusion: Our results imply that mitochondria play a critical role in synaptic plasticity accompanied by increased BDNF levels. Rapid changes in BDNF levels and synaptic/mitochondria plasticity of hippocampus following vortioxetine compared with fluoxetine may be ascribed to vortioxetine's modulation of serotonin receptors.
Subject(s)
Antidepressive Agents/pharmacology , Brain-Derived Neurotrophic Factor/metabolism , CA1 Region, Hippocampal/drug effects , Mitochondria/drug effects , Neuronal Plasticity/drug effects , Vortioxetine/pharmacology , Animals , CA1 Region, Hippocampal/metabolism , CA1 Region, Hippocampal/ultrastructure , Dentate Gyrus/drug effects , Dentate Gyrus/metabolism , Dentate Gyrus/ultrastructure , Dynamins/metabolism , Fluoxetine/pharmacology , Gene Expression/drug effects , Male , Mitochondria/metabolism , Mitochondria/ultrastructure , Neuronal Plasticity/physiology , Proto-Oncogene Proteins c-fos/metabolism , RNA, Messenger/metabolism , Rats, Sprague-Dawley , Synapses/drug effects , Synapses/metabolism , Synapses/ultrastructure , rac1 GTP-Binding Protein/metabolismABSTRACT
The metabolism of tryptophan through kynurenine and serotonin pathways is linked to depression. Here, effects of different drugs with antidepressant properties (vortioxetine, fluoxetine, and ketamine) on various tryptophan metabolites in different brain regions and plasma were examined using tandem mass spectrometry (LC-MS/MS), in Flinders Sensitive Line rats, a genetic rat model of depression, and its controls: Flinders Sensitive Line and Sprague-Dawley rats. Protein levels of kynurenine pathway enzymes were measured in the brains and livers of these rat strains. Furthermore, effects of vortioxetine on tryptophan metabolites were assessed in the cortical regions of lupus mice (MRL/MpJ-FasIpr ), a murine model of increased depression-like behavior associated with inflammation. Sustained vortioxetine or fluoxetine (at doses aimed to fully occupy serotonin transporter via food or drinking water for at least 14 days) reduced levels of the excitotoxin quinolinic acid (QUIN) in various brain regions in all rats. Furthermore, chronic vortioxetine reduced levels of QUIN in MRL/MpJ-FasIpr mice. Acute i.p. administration of fluoxetine (10 mg/kg) or vortioxetine (10 mg/kg) led to reduced brain 5-hydroxyindoleacetic acid in Sprague-Dawley rats (2, 4, 6, and 8 h) and a similar trend was evident in Flinders Sensitive Line and Flinders Sensitive Line rats after 4 h. In contrast, single or repeated administration of ketamine (15 mg/kg i.p.) did not induce significant changes in metabolite levels. In conclusion, sustained vortioxetine and fluoxetine administration decreased QUIN independent of species, while ketamine was ineffective. These results support the hypothesis that modulating tryptophan metabolism may be part of the mechanism of action for some antidepressants.
Subject(s)
Antidepressive Agents/pharmacology , Depression/metabolism , Depression/psychology , Tryptophan/metabolism , Animals , Brain Chemistry/drug effects , Fluoxetine/pharmacology , Frontal Lobe/drug effects , Frontal Lobe/metabolism , Hydroxyindoleacetic Acid/metabolism , Ketamine/pharmacology , Kynurenine/metabolism , Lupus Erythematosus, Systemic/metabolism , Male , Mice , Piperazines/pharmacology , Quinolinic Acid/metabolism , Rats , Rats, Sprague-Dawley , Serotonin Plasma Membrane Transport Proteins/metabolism , Selective Serotonin Reuptake Inhibitors/pharmacology , Sulfides/pharmacology , VortioxetineABSTRACT
BACKGROUND: The identification of biomarkers that predict susceptibility to major depressive disorder and treatment response to antidepressants is a major challenge. Vortioxetine is a novel multimodal antidepressant that possesses pro-cognitive properties and differentiates from other conventional antidepressants on various cognitive and plasticity measures. The aim of the present study was to identify biological systems rather than single biomarkers that may underlie vortioxetine's treatment effects. RESULTS: We show that the biological systems regulated by vortioxetine are overlapping between mouse and rat in response to distinct treatment regimens and in different brain regions. Furthermore, analysis of complexes of physically-interacting proteins reveal that biomarkers involved in transcriptional regulation, neurodevelopment, neuroplasticity, and endocytosis are modulated by vortioxetine. A subsequent qPCR study examining the expression of targets in the protein-protein interactome space in response to chronic vortioxetine treatment over a range of doses provides further biological validation that vortioxetine engages neuroplasticity networks. Thus, the same biology is regulated in different species and sexes, different brain regions, and in response to distinct routes of administration and regimens. CONCLUSIONS: A recurring theme, based on the present study as well as previous findings, is that networks related to synaptic plasticity, synaptic transmission, signal transduction, and neurodevelopment are modulated in response to vortioxetine treatment. Regulation of these signaling pathways by vortioxetine may underlie vortioxetine's cognitive-enhancing properties.
Subject(s)
Antidepressive Agents/pharmacology , Cerebral Cortex/drug effects , Cerebral Cortex/metabolism , Hippocampus/drug effects , Hippocampus/metabolism , Piperazines/pharmacology , Sulfides/pharmacology , Animals , Cerebral Cortex/growth & development , Female , Gene Expression/drug effects , Hippocampus/growth & development , Male , Mice, Inbred C57BL , Neuronal Plasticity/drug effects , Neuronal Plasticity/physiology , Protein Interaction Mapping , RNA, Messenger/metabolism , Rats, Sprague-Dawley , Retrospective Studies , Species Specificity , VortioxetineABSTRACT
Background: Stress is a risk factor for depression and anxiety disorders, disrupting neuronal processes leading to exaggerated fear and compromised coping behaviors. Current antidepressants are only partially effective. Vortioxetine, a novel multimodal antidepressant, is a serotonin transporter inhibitor; 5-HT3, 5-HT7, and 5-HT1D receptor antagonist; 5-HT1B partial agonist; and 5-HT1A agonist. We have shown that chronic dietary vortioxetine administration reversed stress-induced deficits in cognitive flexibility. In the present studies, we investigated the generality of vortioxetine's effects on other stress-related behavioral changes after different types of chronic stress. Methods: In experiment 1, rats were fear-conditioned by pairing a tone with footshock, then exposed to chronic plus acute prolonged stress. In experiment 2, rats were exposed to chronic unpredictable stress. In both experiments, beginning on day 4 of chronic stress, vortioxetine was given in the diet (24 mg/kg/d). In experiment 1, effects of vortioxetine were tested on stress-induced changes in retention and extinction of cue-conditioned fear, and in experiment 2, on coping behavior on the shock probe defensive burying test after chronic stress. Results: Chronic stress exaggerated the expression of conditioned fear memory. Vortioxetine restored fear memory to control levels and rendered extinction in stressed rats comparable with that in controls. In experiment 2, chronic unpredictable stress caused a shift from active to passive coping behavior, and vortioxetine restored active coping. Conclusions: Vortioxetine reduced exaggerated expression of conditioned fear and restored adaptive coping behavior following 2 different types of chronic stress, adding to the evidence of its therapeutic potential in the management of depression and anxiety disorders.
Subject(s)
Adaptation, Psychological/drug effects , Conditioning, Psychological/drug effects , Fear/drug effects , Memory Disorders/drug therapy , Piperazines/pharmacology , Piperazines/therapeutic use , Sulfides/pharmacology , Sulfides/therapeutic use , Analysis of Variance , Animals , Anti-Anxiety Agents/pharmacology , Anti-Anxiety Agents/therapeutic use , Cues , Disease Models, Animal , Electroshock/adverse effects , Extinction, Psychological/drug effects , Immobility Response, Tonic/drug effects , Male , Memory Disorders/etiology , Rats , Rats, Sprague-Dawley , Stress, Psychological/complications , Stress, Psychological/drug therapy , Stress, Psychological/psychology , Time Factors , VortioxetineABSTRACT
Background: Cognitive dysfunction is among the key symptoms of major depressive disorder and can be affected by antidepressants. Cognitive decline also occurs in normal aging. The effects of different antidepressants on affective and cognitive domains in older subjects are seldom assessed simultaneously. Methods: Healthy middle-aged female mice received vehicle or antidepressant (vortioxetine, vilazodone, duloxetine, or fluoxetine) at therapeutic doses. After 1 month treatment, mice were accessed for visuospatial memory and depression-like behavior. A separate cohort of mice received 3 months of treatment and was test for recognition memory and depression-like behavior. Results: After 1 month treatment, vortioxetine improved visuospatial memory and reduced depression-like behavior. Vilazodone reduced depression-like behavior. Duloxetine and fluoxetine were ineffective in both tests. After 3 months treatment, vortioxetine reduced depression-like behavior without affecting recognition memory, while fluoxetine impaired recognition memory. Duloxetine and vilazodone had no effect in both tests. Conclusion: Different antidepressants have distinct effects in middle-aged female mice.
Subject(s)
Aging/drug effects , Antidepressive Agents/pharmacology , Depression/drug therapy , Memory/drug effects , Psychotropic Drugs/pharmacology , Aging/psychology , Animals , Cognition/drug effects , Cohort Studies , Duloxetine Hydrochloride/pharmacology , Female , Fluoxetine/pharmacology , Mice, Inbred C57BL , Piperazines/pharmacology , Random Allocation , Space Perception/drug effects , Sulfides/pharmacology , Vilazodone Hydrochloride/pharmacology , Visual Perception/drug effects , VortioxetineABSTRACT
Major depressive disorder (MDD) is associated with dysfunctional serotonergic and glutamatergic neurotransmission, and the genetic animal model of depression Flinders Sensitive Line (FSL) rats display alterations in these systems relatively to their control strain Flinders Resistant Line (FRL). However, changes on transcript level related to serotonergic and glutamatergic signaling have only been sparsely studied in this model. The non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist ketamine has fast-onset antidepressant properties, and recent data implicate serotonergic neurotransmission in ketamine's antidepressant-like activities in rodents. Here, we investigated the transcript levels of 40 genes involved in serotonergic and glutamatergic neurotransmission in FSL and FRL rats in response to a single dose of ketamine (15 mg/kg; 90 min prior to euthanization). Using real-time quantitative polymerase chain reaction, we studied the effect of ketamine in the hippocampus, whereas strain differences were investigated in both hippocampus and frontal cortex. The expression of genes involved in serotonergic and glutamatergic neurotransmission were unaffected by a single dose of ketamine in the hippocampus. Relative to FRL rats, FSL rats displayed enhanced hippocampal transcript levels of 5-ht2c , and P11, whereas the expression was reduced for 5-ht2a , Nr2a, and Mglur2. In the frontal cortex, we found higher transcript levels of 5-ht2c and Mglur2, whereas the expression of 5-ht2a was reduced in FSL rats. Thus, ketamine is not associated with hippocampal alterations in serotonergic or glutamatergic genes at 90 min after an antidepressant dose. Furthermore, FSL rats display serotonergic and glutamatergic abnormalities on gene expression level that partly may resemble findings in MDD patients.
Subject(s)
Depressive Disorder, Major/metabolism , Excitatory Amino Acid Antagonists/pharmacology , Ketamine/pharmacology , Receptors, Glutamate/genetics , Receptors, Serotonin/genetics , Synaptic Transmission , Animals , Depressive Disorder, Major/genetics , Frontal Lobe/drug effects , Frontal Lobe/metabolism , Hippocampus/drug effects , Hippocampus/metabolism , Male , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rats , Receptors, Glutamate/metabolism , Receptors, Serotonin/metabolismABSTRACT
The recent publication of X-ray structures of SERT includes structures with the potent antidepressant S-Citalopram (S-Cit). Earlier predictions of ligand binding at both a primary (S1) and an allosteric modulator site (S2), were confirmed. We provide herein examples of a series of Citalopram analogs, showing distinct structure-activity relationship (SAR) at both sites that is independent of the SAR at the other site. Analogs with a higher affinity and selectivity than benchmark R-Citalopram (R-Cit) for the S2 versus the S1 site were identified. We deploy structural and computational analyses to explain this SAR and demonstrate the potential utility of the newly emerging X-ray structures within the neurotransmitter:sodium Symporter family for drug design.
Subject(s)
Citalopram/analogs & derivatives , Serotonin Plasma Membrane Transport Proteins/metabolism , Allosteric Site , Binding Sites , Citalopram/chemical synthesis , Citalopram/metabolism , Crystallography, X-Ray , Drug Design , Humans , Inhibitory Concentration 50 , Molecular Dynamics Simulation , Protein Structure, Tertiary , Serotonin Plasma Membrane Transport Proteins/chemistry , Selective Serotonin Reuptake Inhibitors/chemical synthesis , Selective Serotonin Reuptake Inhibitors/chemistry , Selective Serotonin Reuptake Inhibitors/metabolism , Stereoisomerism , Structure-Activity RelationshipABSTRACT
Major depressive disorder (MDD) is a common psychiatric disorder that often features impairments in cognitive function, and these cognitive symptoms can be important determinants of functional ability. Vortioxetine is a multimodal antidepressant that may improve some aspects of cognitive function in patients with MDD, including attention, processing speed, executive function, and memory. However, the cause of these effects is unclear, and there are several competing theories on the underlying mechanism, notably including regionally-selective downstream enhancement of glutamate neurotransmission and increased acetylcholine (ACh) neurotransmission. The current work sought to evaluate the ACh hypothesis by examining vortioxetine's ability to reverse scopolamine-induced impairments in rodent tests of memory and attention. Additionally, vortioxetine's effects on hippocampal extracellular ACh levels were examined alongside studies of vortioxetine's pharmacokinetic profile. We found that acute vortioxetine reversed scopolamine-induced impairments in social and object recognition memory, but did not alter scopolamine-induced impairments in attention. Acute vortioxetine also induced a modest and short-lived increase in hippocampal ACh levels. However, this short-term effect is at variance with vortioxetine's moderately long brain half life (5.1 hours). Interestingly, subchronic vortioxetine treatment failed to reverse scopolamine-induced social recognition memory deficits and had no effects on basal hippocampal ACh levels. These data suggest that vortioxetine has some effects on memory that could be mediated through cholinergic neurotransmission, however these effects are modest and only seen under acute dosing conditions. These limitations may argue against cholinergic mechanisms being the primary mediator of vortioxetine's cognitive effects, which are observed under chronic dosing conditions in patients with MDD.
Subject(s)
Acetylcholine/metabolism , Cognitive Dysfunction/chemically induced , Cognitive Dysfunction/drug therapy , Extracellular Space/drug effects , Hippocampus/pathology , Piperazines/pharmacology , Scopolamine/pharmacology , Sulfides/pharmacology , Animals , Cognitive Dysfunction/metabolism , Cognitive Dysfunction/physiopathology , Extracellular Space/metabolism , Hippocampus/drug effects , Hippocampus/physiopathology , Male , Piperazines/therapeutic use , Rats , Rats, Wistar , Recognition, Psychology/drug effects , Social Behavior , Sulfides/therapeutic use , Synaptic Transmission/drug effects , VortioxetineABSTRACT
The recently reported X-ray structures of the human serotonin (5-HT) transporter SERT with bound inhibitors open new opportunities for drug discovery at SERT, selectivity design with respect to other neurotransmitter sodium transporters, and enhanced understanding of the molecular events involved in SERT action. Through computational and structural analyses, we explore the binding and migration of 5-HT at SERT. Consistent with earlier studies of leucine migration at the bacterial homolog of SERT, LeuT, we find multiple potential 'stopover' sites for 5-HT binding at SERT including the two (transmembrane S1 and extracellular vestibule S2) seen in the binding of the SSRI (S)-citalopram (S-Cit) to SERT, as well as other sites. Docking studies reveal the possibility of both hetero- (S-Cit+5-HT) and homo-dimeric (5-HT+5-HT) co-binding at both these sites which may explain earlier published allosteric activity observations and provide novel design strategies. Comparisons with substrate bound X-ray structures of the dopamine transporter reveal a number of potential sources of selectivity, some of which may be 'artificial' including target based, species related, experimental design related, and ligand dependent examples including substrate versus inhibitor related features.
Subject(s)
Serotonin Plasma Membrane Transport Proteins/chemistry , Crystallography, X-Ray , Humans , Models, Molecular , Protein ConformationABSTRACT
Previous work from this laboratory hypothesized that the multimodal antidepressant vortioxetine enhances cognitive function through a complex mechanism, using serotonergic (5-hydroxytryptamine, 5-HT) receptor actions to modulate gamma-butyric acid (GABA) and glutamate neurotransmission in key brain regions like the prefrontal cortex (PFC) and hippocampus. However, serotonergic receptors have circumscribed expression patterns, and therefore vortioxetine's effects on GABA and glutamate neurotransmission will probably be regionally selective. In this article, we attempt to develop a conceptual framework in which the effects of 5-HT, selective serotonin reuptake inhibitors (SSRIs), and vortioxetine on GABA and glutamate neurotransmission can be understood in the PFC and striatum-2 regions with roles in cognition and substantially different 5-HT receptor expression patterns. Thus, we review the anatomy of the neuronal microcircuitry in the PFC and striatum, anatomical data on 5-HT receptor expression within these microcircuits, and electrophysiological evidence on the effects of 5-HT on the behavior of each cell type. This analysis suggests that 5-HT and SSRIs will have markedly different effects within the PFC, where they will induce mixed effects on GABA and glutamate neurotransmission, compared to the striatum, where they will enhance GABAergic interneuron activity and drive down the activity of medium spiny neurons. Vortioxetine is expected to reduce GABAergic interneuron activity in the PFC and concomitantly increase cortical pyramidal neuron firing. However in the striatum, vortioxetine is expected to increase activity at GABAergic interneurons and have mixed excitatory and inhibitory effects in medium spiny neurons. Thus the conceptual framework developed here suggests that vortioxetine will have regionally selective effects on GABA and glutamate neurotransmission.
Subject(s)
Antidepressive Agents/pharmacology , Neostriatum/drug effects , Piperazines/pharmacology , Prefrontal Cortex/drug effects , Receptors, Serotonin/metabolism , Serotonin Agents/pharmacology , Sulfides/pharmacology , Synaptic Transmission/drug effects , Animals , Brain/drug effects , Brain/metabolism , Glutamic Acid/drug effects , Glutamic Acid/metabolism , Humans , Neostriatum/metabolism , Neurosciences , Prefrontal Cortex/metabolism , Serotonin 5-HT1 Receptor Agonists/pharmacology , Serotonin 5-HT1 Receptor Antagonists/pharmacology , Serotonin 5-HT3 Receptor Antagonists/pharmacology , Selective Serotonin Reuptake Inhibitors/pharmacology , Systems Biology , Vortioxetine , gamma-Aminobutyric Acid/drug effects , gamma-Aminobutyric Acid/metabolismABSTRACT
The hippocampus plays an important role in emotional and cognitive processing, and both of these domains are affected in patients with major depressive disorder (MDD). Extensive preclinical research and the notion that modulation of serotonin (5-HT) neurotransmission plays a key role in the therapeutic efficacy of selective serotonin reuptake inhibitors (SSRIs) support the view that 5-HT is important for hippocampal function in normal and disease-like conditions. The hippocampus is densely innervated by serotonergic fibers, and the majority of 5-HT receptor subtypes are expressed there. Furthermore, hippocampal cells often co-express multiple 5-HT receptor subtypes that can have either complementary or opposing effects on cell function, adding to the complexity of 5-HT neurotransmission. Here we review the current knowledge of how 5-HT, through its various receptor subtypes, modulates hippocampal output and the activity of hippocampal pyramidal cells in rodents. In addition, we discuss the relevance of 5-HT modulation for cognitive processing in rodents and possible clinical implications of these results in patients with MDD. Finally, we review the data on how SSRIs and vortioxetine, an antidepressant with multimodal activity, affect hippocampal function, including cognitive processing, from both a preclinical and clinical perspective.
Subject(s)
Antidepressive Agents/pharmacology , Depressive Disorder, Major/metabolism , Hippocampus/drug effects , Pyramidal Cells/drug effects , Receptors, Serotonin/drug effects , Selective Serotonin Reuptake Inhibitors/pharmacology , Serotonin/metabolism , Antidepressive Agents/therapeutic use , Depressive Disorder, Major/drug therapy , Hippocampus/metabolism , Humans , Pyramidal Cells/metabolism , Receptors, Serotonin/metabolism , Selective Serotonin Reuptake Inhibitors/therapeutic use , Synaptic TransmissionABSTRACT
Spatial prioritizations are essential tools for conserving biodiversity in the face of accelerating climate change. Uncertainty about species' responses to changing climates can complicate prioritization efforts, however, and delay conservation investment. In an effort to facilitate decision-making, we identified three hypotheses about species' potential responses to climate change based on distinct biological assumptions related to niche flexibility and colonization ability. Using 314 species of North American birds as a test case, we tuned separate spatial prioritizations to each hypothesis and assessed the degree to which assumptions about biological responses affected the perceived conservation value of the landscape and prospects for individual taxa. We also developed a bet-hedging prioritization to minimize the chance that incorrect assumptions would lead to valuable landscapes and species being overlooked in multispecies prioritizations. Collectively, these analyses help to quantify the sensitivity of spatial prioritizations to different assumptions about species' responses to climate change and provide a framework for enabling efficient conservation investment despite substantial biological uncertainty.
Subject(s)
Animal Distribution , Birds/physiology , Climate Change , Uncertainty , Animals , Computer Simulation , Models, Biological , North America , SoftwareABSTRACT
Neuropsychiatric symptoms of systemic lupus erythematosus (NP-SLE) have been understudied compared to end-organ failure and peripheral pathology. Neuropsychiatric symptoms, particularly affective and cognitive indications, may be among the earliest manifestations of SLE. Among the potential pathophysiological mechanisms responsible for NP-SLE are increased peripheral pro-inflammatory cytokines, subsequent induction of indoleamine-2,3-dioxygenase (IDO) and activation of the kynurenine pathway. In the MRL/MpJ-Faslpr (MRL/lpr) murine model of lupus, depression-like behavior and cognitive dysfunction is evident before significant levels of autoantibody titers and nephritis are present. We examined the behavioral profile of MRL/lpr mice and their congenic controls, a comprehensive plasma cytokine and chemokine profile, and brain levels of serotonin and kynurenine pathway metabolites. Consistent with previous studies, MRL/lpr mice had increased depression-like behavior and visuospatial memory impairment. Plasma levels of different inflammatory molecules (Haptoglobin, interleukin 10 (IL-10), interferon γ-inducible protein 10 (IP-10/CXCL10), lymphotactin, macrophage inhibitory protein 3ß (MIP-3ß/CCL19), monocyte chemotactic protein 1, 3 and 5 (MCP-1/CCL2, MCP-3/CCL7, MCP-5/CCL12), vascular cell adhesion molecule 1 (VCAM-1), lymphotactin and interferon γ (IFN-γ)) were increased in MRL/lpr mice. In cortex and hippocampus, MRL/lpr mice had increased levels of kynurenine pathway metabolites (kynurenine, 3-hydroxykynurenine, 3-hydroxynthranilic acid and quinolinic acid). Therefore, our study suggests that increased cytokine expression may be critical in the regulation subtle aspects of brain function in NP-SLE via induction of IDO and tryptophan/kynurenine metabolism.
Subject(s)
Behavior, Animal , Lupus Vasculitis, Central Nervous System/metabolism , Animals , Cerebral Cortex/metabolism , Chemokines/genetics , Chemokines/metabolism , Cytokines/genetics , Cytokines/metabolism , Hippocampus/metabolism , Kynurenine/metabolism , Lupus Vasculitis, Central Nervous System/immunology , Lupus Vasculitis, Central Nervous System/physiopathology , Memory , Mice , Mice, Inbred C57BLABSTRACT
Current treatments for depression, including serotonin-specific reuptake inhibitors (SSRIs), are only partially effective, with a high incidence of residual symptoms, relapse, and treatment resistance. Loss of cognitive flexibility, a component of depression, is associated with dysregulation of the prefrontal cortex. Reversal learning, a form of cognitive flexibility, is impaired by chronic stress, a risk factor for depression, and the stress-induced impairment in reversal learning is sensitive to chronic SSRI treatment, and is mimicked by serotonin (5-HT) depletion. Vortioxetine, a novel, multimodal-acting antidepressant, is a 5-HT3, 5-HT7 and 5-HT1D receptor antagonist, a 5-HT1B receptor partial agonist, a 5-HT1A receptor agonist, and inhibits the 5-HT transporter. Using adult male rats, we first investigated the direct effects of vortioxetine, acting at post-synaptic 5-HT receptors, on reversal learning that was compromised by 5-HT depletion using 4-chloro-DL-phenylalanine methyl ester hydrochloride (PCPA), effectively eliminating any contribution of 5-HT reuptake blockade. PCPA induced a reversal learning impairment that was alleviated by acute or sub-chronic vortioxetine administration, suggesting that post-synaptic 5-HT receptor activation contributes to the effects of vortioxetine. We then investigated the effects of chronic dietary administration of vortioxetine on reversal learning that had been compromised in intact animals exposed to chronic intermittent cold (CIC) stress, to assess vortioxetine's total pharmacological effect. CIC stress impaired reversal learning, and chronic vortioxetine administration prevented the reversal-learning deficit. Together, these results suggest that the direct effect of vortioxetine at 5-HT receptors may contribute to positive effects on cognitive flexibility deficits, and may enhance the effect of 5-HT reuptake blockade.