The tail suspension test

Mesenchymal stromal cells protect against vascular damage and depression-like behavior in mice surviving cerebral malaria

BACKGROUND

Malaria is one of the most critical global infectious diseases. Severe systemic inflammatory diseases, such as cerebral malaria, lead to the development of cognitive and behavioral alterations, such as learning disabilities and loss of memory capacity, as well as increased anxiety and depression. The consequences are profound and usually contribute to reduce the patient's quality of life. There are no therapies to treat the neurological sequelae of cerebral malaria. Mesenchymal stromal cells (MSCs) may be an alternative, since they have been used as therapy for neurodegenerative diseases and traumatic lesions of the central nervous system. So far, no study has investigated the effects of MSC therapy on the blood-brain barrier, leukocyte rolling and adherence in the brain, and depression like-behavior in experimental cerebral malaria.

METHODS

Male C57BL/6 mice were infected with Plasmodium berghei ANKA (PbA, 1 × 106 PbA-parasitized red blood cells, intraperitoneally). At day 6, PbA-infected animals received chloroquine (25 mg/kg orally for seven consecutive days) as the antimalarial treatment and were then randomized to receive MSCs (1 × 105 cells in 0.05 ml of saline/mouse) or saline (0.05 ml) intravenously. Parasitemia, clinical score, and survival rate were analyzed throughout the experiments. Evans blue assay was performed at 6, 7, and 15 days post-infection (dpi). Behavioral tests were performed at 5 and 15 dpi. Intravital microscopy experiments and brain-derived neurotrophic factor (BDNF) protein expression analyses were performed at 7 dpi, whereas inflammatory mediators were measured at 15 dpi. In vitro, endothelial cells were used to evaluate the effects of conditioned media derived from MSCs (CMMSC) on cell viability by lactate dehydrogenase (LDH) release.

RESULTS

PbA-infected mice presented increased parasitemia, adherent leukocytes, blood-brain barrier permeability, and reduced BDNF protein levels, as well as depression-like behavior. MSCs mitigated behavioral alterations, restored BDNF and transforming growth factor (TGF)-β protein levels, and reduced blood-brain barrier dysfunction and leukocyte adhesion in the brain microvasculature. In a cultured endothelial cell line stimulated with heme, CMMSC reduced LDH release, suggesting a paracrine mechanism of action.

CONCLUSION

A single dose of MSCs as adjuvant therapy protected against vascular damage and improved depression-like behavior in mice that survived experimental cerebral malaria.

Sepsis survivor mice exhibit a behavioral endocrine syndrome with ventral hippocampal dysfunction

Severe acute stressors are known to trigger mood disorders in humans. Sepsis represents one such stressor, and survivors often suffer long term from psychiatric morbidity. We hypothesized that sepsis leads to lasting changes in neural circuits involved in stress integration, altering affective behavior and the stress response. To investigate this hypothesis, sepsis was induced in male C57Bl/6 mice using cecal ligation and puncture (CLP), and control mice underwent sham surgery. Mice recovered from acute illness within 2 weeks, after which they exhibited increased avoidance behavior and behavioral despair compared with sham, with behavioral changes observed more than 5 weeks after recovery. Sepsis survivors also showed evidence of enhanced hypothalamic-pituitary-adrenal (HPA) axis activity, with increased corticosterone after a novel stressor and increased adrenal weight. In the brain, sepsis survivor mice showed decreased stress-induced cfos mRNA and increased glucocorticoid receptor immunoreactivity specifically in the ventral hippocampus, a brain region known to coordinate emotional behavior and HPA axis activity. We conclude that murine sepsis survivors exhibit a behavioral neuroendocrine syndrome of negative affective behavior and HPA axis hyperactivity, which could be explained by ventral hippocampal dysfunction. These findings could contribute to our understanding of the human post-intensive care syndrome.

Calpain-2 as a therapeutic target in repeated concussion-induced neuropathy and behavioral impairment

Repeated concussion represents a serious health problem as it can result in various brain pathologies, ranging from minor focal tissue injury to severe chronic traumatic encephalopathy. The calcium-dependent protease, calpain, participates in the development of neurodegeneration following concussion, but there is no information regarding the relative contribution of calpain-1 and calpain-2, the major calpain isoforms in the brain. We used a mouse model of repeated concussions, which reproduces most of the behavioral and neuropathological features of the human condition, to address this issue. Deletion of calpain-2 or treatment with a selective calpain-2 inhibitor for 2 weeks prevented most of these neuropathological features. Changes in TAR DNA binding protein 43 (TDP-43) subcellular localization similar to those found in human amyotrophic lateral sclerosis and frontotemporal dementia were also prevented by deletion of calpain-2 or treatment with calpain-2 inhibitor. Our results indicate that a selective calpain-2 inhibitor represents a therapeutic approach for concussion.

Absence of Glia Maturation Factor Protects from Axonal Injury and Motor Behavioral Impairments after Traumatic Brain Injury

Traumatic brain injury (TBI) causes disability and death, accelerating the progression towards Alzheimer's disease and Parkinson's disease (PD). TBI causes serious motor and cognitive impairments, as seen in PD that arise during the period of the initial insult. However, this has been understudied relative to TBI induced neuroinflammation, motor and cognitive decline that progress towards PD. Neuronal ubiquitin-C-terminal hydrolase- L1 (UCHL1) is a thiol protease that breaks down ubiquitinated proteins and its level represents the severity of TBI. Previously, we demonstrated the molecular action of glia maturation factor (GMF); a proinflammatory protein in mediating neuroinflammation and neuronal loss. Here, we show that the weight drop method induced TBI neuropathology using behavioral tests, western blotting, and immunofluorescence techniques on sections from wild type (WT) and GMF-deficient (GMF-KO) mice. Results reveal a significant improvement in substantia nigral tyrosine hydroxylase and dopamine transporter expression with motor behavioral performance in GMF-KO mice following TBI. In addition, a significant reduction in neuroinflammation was manifested, as shown by activation of nuclear factor-kB, reduced levels of inducible nitric oxide synthase, and cyclooxygenase- 2 expressions. Likewise, neurotrophins including brain-derived neurotrophic factor and glial-derived neurotrophic factor were significantly improved in GMF-KO mice than WT 72 h post-TBI. Consistently, we found that TBI enhances GFAP and UCHL-1 expression and reduces the number of dopaminergic TH-positive neurons in WT compared to GMF-KO mice 72 h post-TBI. Interestingly, we observed a reduction of THpositive tanycytes in the median eminence of WT than GMF-KO mice. Overall, we found that absence of GMF significantly reversed these neuropathological events and improved behavioral outcome. This study provides evidence that PD-associated pathology progression can be initiated upon induction of TBI.

Telomerase gene therapy ameliorates the effects of neurodegeneration associated to short telomeres in mice

Neurodegenerative diseases associated with old age such as Alzheimer’s disease present major problems for society, and they currently have no cure. The telomere protective caps at the ends of chromosomes shorten with age, and when they become critically short, they can induce a persistent DNA damage response at chromosome ends, triggering secondary cellular responses such as cell death and cellular senescence. Mice and humans with very short telomeres owing to telomerase deficiencies have an earlier onset of pathologies associated with loss of the regenerative capacity of tissues. However, the effects of short telomeres in very low proliferative tissues such as the brain have not been thoroughly investigated. Here, we describe a mouse model of neurodegeneration owing to presence of short telomeres in the brain as the consequence of telomerase deficiency. Interestingly, we find similar signs of neurodegeneration in very old mice as the consequence of physiological mouse aging. Next, we demonstrate that delivery of telomerase gene therapy to the brain of these mice results in amelioration of some of these neurodegeneration phenotypes. These findings suggest that short telomeres contribute to neurodegeneration diseases with aging and that telomerase activation may have a therapeutic value in these diseases.

Amelioration of BPSD-Like Phenotype and Cognitive Decline in SAMP8 Mice Model Accompanied by Molecular Changes after Treatment with I2-Imidazoline Receptor Ligand MCR5

Behavioural and psychological symptoms of dementia (BPSD), including fear-anxiety- and depressive-like behaviour, are present in Alzheimer's disease (AD), together with memory decline. I₂-imidazoline receptors (I₂-IRs) have been associated with neuropsychiatric and neurodegenerative disorders, further, I₂-IR ligands have demonstrated a neuroprotective role in the central nervous system (CNS). In this study, we assessed the effect of the I₂-IR ligand MCR5 on both cognitive and non-cognitive symptoms in the Senescence accelerated mice prone 8 (SAMP8) mouse model. Oral administration of I₂-IR ligand MCR5 (5 mg/kg/day for four weeks) in 10-month SAMP8 mice ameliorated both BPSD-like phenotype and cognitive decline by attenuating depressive-like behaviour, reducing fear-anxiety-like behaviour and improving cognitive performance using different tasks. Interaction of I₂-IR ligand MCR5 with serotoninergic system did not account for behavioural or cognitive improvement, although changes in molecular pathways underlying depression and anxiety phenotype were observed. MCR5 increased levels of p-AKT, phosphorylated glycogen synthase kinase 3 β (GSK3β) at Ser9 and phosphorylated mammalian target of rapamycin complex 1 (mTORC1) levels in SAMP8 treated mice compared to SAMP8 control. Moreover, MCR5 treatment altered N-methyl-d-aspartate receptor (NMDA) 2B phosphorylation, and decreased the protein levels of phosphorylated cyclin-dependent kinase 5 (p-CDK5) and dopamine- and cyclic adenosine monophosphate (cAMP)-regulated phosphoprotein of Mr 32 kDa phosphorylated at Thr75 (p-DARPP32), with a parallel increase in protein kinase A (PKA) and p-cAMP response element-binding (pCREB) levels. Consistent with these changes MCR5 attenuated neuroinflammation by decreasing expression of pro-inflammatory markers such as Tumor necrosis factor-alpha (Tnf-α), Interleukin 1β (Il-1β), Interleukin 6 (Il-6), and promoted synaptic plasticity by increasing levels of postsynaptic density protein 95 (PSD95) as well as ameliorating tropomyosin-related kinase B (TrkB) and nerve growth factor receptor (NGFR) signalling. Collectively, these results increase the potential of highly selective I₂-IR ligands as therapeutic agents in age-related BPSD and cognitive alterations.

Neuroprotection of Glibenclamide against Brain Injury after Cardiac Arrest via Modulation of NLRP3 Inflammasome

Glibenclamide (GBC) improves cerebral outcome after cardiac arrest (CA) in rats. We aim to investigate the effect of GBC on electrophysiological recovery and to explore the mechanism of neuroprotective effects of GBC on the acute stage of brain injury after the return of spontaneous circulation (ROSC) in a rodent model of CA. 16 anesthetized male Wistar rats subjected to 8-min asphyxia-CA were randomly assigned to the GBC or control group (N=8 each group). GBC was administered with a loading dose of 10ug/kg i. p. injection 10 min after ROSC and followed with a maintaining dose of 1.6ug/kg per 8 hours throughout the first 24 hours. Quantitative measures of EEG-information quantity (qEEG-IQ) and neurological deficit score (NDS) were used to predict and evaluate the functional outcome. There was a significant improvement of NDS in rats treated with GBC compared with the control group (p <; 0.01). Compared to the control group, the rats treated with GBC showed qEEG-IQ scores that indicated better recovery (p <; 0.001). Meanwhile, early QEEG-IQ was significantly correlated with 72-hr NDS as early as 45min after ROSC. Furthermore, on the molecular basis, the NLRP3 inflammasome was strongly activated in the hippocampal CA1 area 3 days after CA in control rats, which was suppressed with GBC treatment. Taken together, GBC treatment markedly improved electrophysiological and neurologic outcomes of the acute brain injury after CA. These neuroprotective effects may be associated with the attenuation of inflammatory response via down-regulation of NLRP3 inflammasome signal.

Historical Perspective: Models of Parkinson's Disease

Parkinson’s disease (PD) is the most common movement disorder with motor and nonmotor signs. The current therapeutic regimen for PD is mainly symptomatic as the etio-pathophysiology has not been fully elucidated. A variety of animal models has been generated to study different aspects of the disease for understanding the pathogenesis and therapeutic development. The disease model can be generated through neurotoxin-based or genetic-based approaches in a wide range of animals such as non-human primates (NHP), rodents, zebrafish, Caenorhabditis (C.) elegans, and drosophila. Cellular-based disease model is frequently used because of the ease of manipulation and suitability for large-screen assays. In neurotoxin-induced models, chemicals such as 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), rotenone, and paraquat are used to recapitulate the disease. Genetic manipulation of PD-related genes, such as α-Synuclein(SNCA), Leucine-rich repeat kinase 2 (LRRK2), Pten-Induced Kinase 1 (PINK1), Parkin(PRKN), and Protein deglycase (DJ-1) Are used in the transgenic models. An emerging model that combines both genetic- and neurotoxin-based methods has been generated to study the role of the immune system in the pathogenesis of PD. Here, we discuss the advantages and limitations of the different PD models and their utility for different research purposes.

Participation of the nucleus accumbens dopaminergic system in the antidepressant-like actions of a diet rich in omega-3 polyunsaturated fatty acids

The beneficial effects of omega (ω)-3 polyunsaturated fatty acid (PUFA) supplementation on major depressive disorder have been actively studied, but the underlying mechanism remains unknown. The present study examined the involvement of the nucleus accumbens (NAc) dopaminergic systems in behavioral changes in mice fed a diet high in ω-3 PUFAs. Mice fed a diet containing about double the amount of ω-3 PUFAs (krill oil (KO) diet) exerted shorter immobility times in the forced swim test (FST) than mice fed a control diet, containing only α-linolenic acid (ALA) as ω-3 PUFAs. The shorter immobility times were observed in both male and female mice. A dopamine metabolite, 3,4-dihydroxyphenylacetic acid, increased in the NAc in male mice fed the KO diet when compared with those fed the control diet. In addition, dopamine, 3-methoxytyramine, and homovanillic acid increased in the NAc in female mice fed the KO diet. Notably, the effects of the KO diet on the immobility time in the FST were abolished by microinjection of sulpiride, an antagonist of D₂-like receptors, into the NAc. A similar microinjection of an antagonist selective for D₁-like receptors, SKF83566, also abolished the reduction in immobility in the FST. Moreover, we found that tyrosine hydroxylase-positive cells increased in the ventral tegmental area (VTA) in mice fed the KO diet. These results suggest that modulation of the VTA-NAc dopaminergic pathway is one of the mechanisms by which a KO diet rich in ω-3 PUFAs reduces the immobility behavior in the mouse FST.

Severe hydroxymethylbilane synthase deficiency causes depression-like behavior and mitochondrial dysfunction in a mouse model of homozygous dominant acute intermittent porphyria

Acute intermittent porphyria (AIP) is an autosomal dominant inborn error of heme biosynthesis due to a pathogenic mutation in the Hmbs gene, resulting in half-normal activity of hydroxymethylbilane synthase. Factors that induce hepatic heme biosynthesis induce episodic attacks in heterozygous patients. The clinical presentation of acute attacks involves the signature neurovisceral pain and may include psychiatric symptoms. Here we used a knock-in mouse line that is biallelic for the Hmbs c.500G > A (p.R167Q) mutation with ~ 5% of normal hydroxymethylbilane synthase activity to unravel the consequences of severe HMBS deficiency on affective behavior and brain physiology. Hmbs knock-in mice (KI mice) model the rare homozygous dominant form of AIP and were used as tool to elucidate the hitherto unknown pathophysiology of the behavioral manifestations of the disease and its neural underpinnings. Extensive behavioral analyses revealed a selective depression-like phenotype in Hmbs KI mice; transcriptomic and immunohistochemical analyses demonstrated aberrant myelination. The uncovered compromised mitochondrial function in the hippocampus of knock-in mice and its ensuing neurogenic and neuroplastic deficits lead us to propose a mechanistic role for disrupted mitochondrial energy production in the pathogenesis of the behavioral consequences of severe HMBS deficiency and its neuropathological sequelae in the brain.

Astrocyte-Specific Deletion of Sox2 Promotes Functional Recovery After Traumatic Brain Injury

Injury to the adult brain induces activation of local astrocytes, which serves as a compensatory response that modulates tissue damage and recovery. However, the mechanism governing astrocyte activation during brain injury remains largely unknown. Here we provide in vivo evidence that SOX2, a transcription factor critical for stem cells and brain development, is also required for injury-induced activation of adult cortical astrocytes. Genome-wide chromatin immunoprecipitation-seq analysis of mouse cortical tissues reveals that SOX2 binds to regulatory regions of genes associated with signaling pathways that control glial cell activation, such as Nr2e1, Mmd2, Wnt7a, and Akt2. Astrocyte-specific deletion of Sox2 in adult mice greatly diminishes glial response to controlled cortical impact injury and, most unexpectedly, dampens injury-induced cortical loss and benefits behavioral recovery of mice after injury. Together, these results uncover an essential role of SOX2 in somatic cells under pathological conditions and indicate that SOX2-dependent astrocyte activation could be targeted for functional recovery after traumatic brain injury.

Selective activation of estrogen receptors α and β: Implications for depressive-like phenotypes in female mice exposed to chronic unpredictable stress

The estrogen receptor (ER) mechanisms by which 17β-estradiol influences depressive-like behaviour have primarily been investigated acutely and not within an animal model of depression. Therefore, the current study aimed to dissect the contribution of ERα and ERβ to the effects of 17β-estradiol under non-stress and chronic stress conditions. Ovariectomized (OVX) or sham-operated mice were treated chronically (47 days) with 17β-estradiol (E2), the ERβ agonist diarylpropionitrile (DPN), the ERα agonist propylpyrazole-triol (PPT), or vehicle. On day 15 of treatment, mice from each group were assigned to chronic unpredictable stress (CUS; 28 days) or non-CUS conditions. Mice were assessed for anxiety- and depressive-like behaviour and hypothalamic-pituitary-adrenal (HPA) axis function. Cytokine and chemokine levels, and postsynaptic density protein 95 were measured in the hippocampus and frontal cortex, and adult hippocampal neurogenesis was assessed. Overall, the effects of CUS were more robust that those of estrogenic treatments, as seen by increased immobility in the tail suspension test (TST), reduced PSD-95 expression, reduced neurogenesis in the ventral hippocampus, and HPA axis negative feedback dysregulation. However, we also observe CUS-dependent and -independent effects of ovarian status and estrogenic treatments. The effects of CUS on PSD-95 expression, the cytokine milieu, and in TST were largely driven by PPT and DPN, indicating that these treatments were not protective. Independent of CUS, estradiol increased neurogenesis in the dorsal hippocampus, blunted the corticosterone response to an acute stressor, and increased anxiety-like behaviour. These findings provide insights into the complexities of estrogen signaling in modulating depressive-like phenotypes under non-stress and chronic stress conditions.

Expression of Behavioral Phenotypes in Genetic and Environmental Mouse Models of Schizophrenia

Schizophrenia is a neuropsychiatric disorder characterized by multifactorial etiology involving complex interactions among genetic and environmental factors. "Multiple-hit" models of the disorder can explain its variable incidence and prevalence in related individuals. Hence, there is a dire need to understand these interactions in the emergence of schizophrenia. To test these factors in the emergence of schizophrenia-like behaviors, we employed a genetic mouse model of the disorder (harboring the DISC1 mutation) along with various environmental insults, such as early life stress (maternal separation of pups) and/or pharmacological interventions (ketamine injections). When assessed on a battery of behavioral tests, we found that environmental interventions affect the severity of behavioral phenotypes in terms of increased negative behavior, as shown by reduced mobility in the forced swim and tail suspension tests, and changes to positive and cognitive symptoms, such as increased locomotion and disrupted PPI along with reduced working memory, respectively. Among the various interventions, the genetic mutation had the most profound effect on behavioral aberrations, followed by an environmental intervention by ketamine injections and ketamine-injected animals that were maternally separated during early postnatal days. We conclude that although environmental factors increased the prevalence of aberrant behavioral phenotypes, genetic background is still the predominant influence on phenotypic alterations in these mouse models of schizophrenia.

Elimination of galanin synthesis in noradrenergic neurons reduces galanin in select brain areas and promotes active coping behaviors

Accumulating evidence indicates that disruption of galanin signaling is associated with neuropsychiatric disease, but the precise functions of this neuropeptide remain largely unresolved due to lack of tools for experimentally disrupting its transmission in a cell type-specific manner. To examine the function of galanin in the noradrenergic system, we generated and crossed two novel knock-in mouse lines to create animals lacking galanin specifically in noradrenergic neurons (Gal^cKO-Dbh). We observed reduced levels of galanin peptide in pons, hippocampus, and prefrontal cortex of Gal^cKO-Dbh mice, indicating that noradrenergic neurons are a significant source of galanin to those brain regions, while midbrain and hypothalamic galanin levels were comparable to littermate controls. In these same brain regions, we observed no change in levels of norepinephrine or its major metabolite at baseline or after an acute stressor, suggesting that loss of galanin does not affect noradrenergic synthesis or turnover. Gal^cKO-Dbh mice had normal performance in tests of depression, learning, and motor-related behavior, but had an altered response in some anxiety-related tasks. Specifically, Gal^cKO-Dbh mice showed increased marble and shock probe burying and had a reduced latency to eat in a novel environment, indicative of a more proactive coping strategy. Together, these findings indicate that noradrenergic neurons provide a significant source of galanin to discrete brain areas, and noradrenergic-specific galanin opposes adaptive coping responses.

Finding intestinal fortitude: Integrating the microbiome into a holistic view of depression mechanisms, treatment, and resilience

Depression affects at least 322 million people globally, or approximately 4.4% of the world's population. While the earnestness of researchers and clinicians to understand and treat depression is not waning, the number of individuals suffering from depression continues to increase over and above the rate of global population growth. There is a sincere need for a paradigm shift. Research in the past decade is beginning to take a more holistic approach to understanding depression etiology and treatment, integrating multiple body systems into whole-body conceptualizations of this mental health affliction. Evidence supports the hypothesis that the gut microbiome, or the collective trillions of microbes inhabiting the gastrointestinal tract, is an important factor determining both the risk of development of depression and persistence of depressive symptoms. This review discusses recent advances in both rodent and human research that explore bidirectional communication between the gut microbiome and the immune, endocrine, and central nervous systems implicated in the etiology and pathophysiology of depression. Through interactions with circulating inflammatory markers and hormones, afferent and efferent neural systems, and other, more niche, pathways, the gut microbiome can affect behavior to facilitate the development of depression, exacerbate current symptoms, or contribute to treatment and resilience. While the challenge of depression may be the direst mental health crisis of our age, new discoveries in the gut microbiome, when integrated into a holistic perspective, hold great promise for the future of positive mental health.

Antidiabetic Drug Metformin Ameliorates Depressive-Like Behavior in Mice with Chronic Restraint Stress via Activation of AMP-Activated Protein Kinase

Depression is one of the most prevalent neuropsychiatric disorders in modern society. However, traditional drugs, such as monoaminergic agents, have defect showing lag response requiring several weeks to months. Additionally, these drugs have limited efficacy and high resistance rates in patients with depression. Thus, there is an urgent need to develop novel drugs or approaches for the treatment of depression. Here, using biochemical, pharmacological, genetic and behavioral methods, we demonstrate that metformin imparts a fast-acting antidepressant-like effect in naïve mice as well as stressed mice subjected to chronic restraint stress model. Moreover, inhibition of AMP-activated protein kinase (AMPK) activity by compound C or knock down of hippocampal AMPKα occluded the antidepressant-like effect induced by metformin. Our results suggest that metformin may be a viable therapeutic drug for the treatment of stress-induced depression via activation of AMPK.

Co-expression Network of mRNAs and lncRNAs Regulated by Stress-Linked Behavioral Assays

RATIONALE

Mood-related behavioral assays, designed typically on rodents' natural aversion to certain threats, are useful in studying the mechanisms of mood and in discovering effective treatments for neuropsychiatric disorders.

OBJECTIVES

Although reasonable attention has been paid to the conducted sequence, few studies address the argument whether a behavioral assay itself affects the intrinsic signaling, gene expression, and the subsequent performance of mice.

METHODS

We examined the short- (1 day) and long-term effects (7 and 14 days) of commonly used behavioral assays for anxiety and depression, including the elevated plus maze test (EPM), forced swimming test (FST), and tail suspension test (TST), on behaviors. We also investigated the effects of repeated behavioral assays on behaviors. The alterations in the expression profiles in the hippocampus experienced behavioral assays were explored via the integrative analysis of mRNA and lncRNA transcriptomes generated by RNA sequencing.

RESULTS

We found that one FST or TST can induce anxiety-related behaviors, while repeated FST or TST resulted in depression-related behaviors in mice. The altered behaviors were associated with extensive transcriptional alterations in the FST and TST hippocampus of mice. KEGG pathway analyses indicated that differentially expressed genes (DEGs) in the FST and TST hippocampus were enriched in anxiety- and metabolic-related pathways, respectively. Moreover, differentially expressed lncRNAs, showing correlations with DEGs, were linked to anxiety-related pathways in the FST hippocampus and metabolic-related pathways in the TST hippocampus.

CONCLUSIONS

Our study identified the unique and shared mRNAs and lncRNAs regulated by mood-related behavioral assays, emphasizing the importance of the sequence of and intervals between them.

Uwhangchungsimwon, A Standardized Herbal Drug, Exerts an Anti-Depressive Effect in a Social Isolation Stress-Induced Mouse Model

Introduction

Uwhangchungsimwon (UCW) is one of the most representative standardized herbal drugs for the treatment of central nervous system diseases, including mood disorders, and has been used for over 600 years in Korea and China. In spite of the long clinical application of UCW, no experimental evidence for its use against depressive disorders exists. Here, we performed an animal study to investigate the anti-depressive effect of UCW and the underlying mechanisms.

Methods

A social isolation-induced depressive-like model was produced using C57BL/6J male mice by housing the mice individually for 31 days, and the mice underwent daily oral administration of distilled water, UCW (100, 200, 400 mg/kg) or fluoxetine (20 mg/kg) during the final 17 days. A tail suspension test (TST), forced swimming test (FST), and open field test (OFT) were used to explore the effects of UCW on depressive-like behaviors. 5-Hydroxytryptamine (5-HT) was measured in the dorsal raphe nuclei (DRN) using immunofluorescence. The serum corticosterone level was measured with its receptor and catecholamine, along with cAMP response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in the hippocampus.

Results

Social isolation stress effectively induced depressive-like behaviors, and UCW treatment significantly improved the symptoms of depressive-like behavior in the FST, TST, and OFT. The isolation stress-induced depletion of 5-HT was significantly ameliorated by UCW treatment. UCW also attenuated the activation of the glucocorticoid receptor (GR) and the elevated serum corticosterone level, as well as the hippocampal levels of dopamine and norepinephrine. Dexametasone-derived translocation of GR was inhibited by UCW treatment in PC12 cells and HT22 cells. In addition, alterations of tryptophan hydroxylase 2 (TPH2), BDNF, and CREB in the protein analyses were notably regulated by UCW treatment.

Conclusions

These results provide animal-based evidence for the anti-depressive effect of UCW, and its underlying mechanisms may involve regulating the serotonergic system, the hypothalamic-pituitary-adrenal (HPA) axis, and neurotrophin.

Behavioral Traits Associated With Resilience to the Effects of Repeated Social Defeat on Cocaine-Induced Conditioned Place Preference in Mice

The relationship between stress and drug use is well demonstrated. Stress-induced by repeated social defeat (RSD) enhances the conditioned place preference (CPP) induced by cocaine in mice. The phenomenon of resilience understood as the ability of subjects to overcome the negative effects of stress is the focus of increasing interest. Our aim is to characterize the behavior of resilient animals with respect to the effects of RSD on the CPP induced by cocaine. To this end, 25 male C57BL/6 mice were exposed to stress by RSD during late adolescence, while other 15 male mice did not undergo stress (controls). On the 2 days following the last defeat, all the animals carried out the elevated plus maze (EPM) and Hole Board, Social Interaction, Tail Suspension and Splash tests. Three weeks later, all the animals performed the CPP paradigm with a low dose of cocaine (1 mg/kg). Exposure to RSD decreased all measurements related to the open arms of the EPM. It also reduced social interaction, immobility in the tail suspension test (TST) and grooming in the splash test. RSD exposure also increased the sensitivity of the mice to the rewarding effects of cocaine, since only defeated animals acquired CPP. Several behavioral traits were related to resilience to the potentiating effect of RSD on cocaine CPP. Mice that showed less submission during defeat episodes, a lower percentage of time in the open arms of the EPM, low novelty-seeking, high social interaction, greater immobility in the TST and a higher frequency of grooming were those that were resilient to the long-term effects of social defeat on cocaine reward since they behaved like controls and did not develop CPP. These results suggest that the behavioral profile of resilient defeated mice is characterized by an active coping response during episodes of defeat, a greater concern for potential dangers, less reactivity in a situation of inevitable moderate stress and fewer depressive-like symptoms after stress. Determining the neurobehavioral substrates of resilience is the first step towards developing behavioral or pharmacological interventions that increase resilience in individuals at a high risk of suffering from stress.

Adolescent stress increases depression-like behaviors and alters the excitatory-inhibitory balance in aged mice

Background:

Depression affects approximately 5% of elderly people and its etiology might be related to chronic stress exposure during neurodevelopmental periods. In this study, we examined the effects of adolescent chronic social stress in aged mice on depressive behaviors and the excitatory-inhibitory (E/I) balance in stress-sensitive regions of the brain.

Methods:

Sixty-four adolescent, male C57BL/6 mice were randomly assigned to either the 7-week (from post-natal days 29 to 77) social instability stress (stress group, n = 32) or normal housing conditions (control group, n = 32). At 15 months of age, 16 mice were randomly selected from each group for a series of behavioral tests, including two depression-related tasks (the sucrose preference test and the tail suspension test). Three days following the last behavioral test, eight mice were randomly selected from each group for immunohistochemical analyses to measure the cell density of parvalbumin (PV⁺)- and calretinin (CR⁺)-positive gamma-aminobutyric-acid (GABA)ergic inhibitory inter-neurons, and the expression levels of vesicular transporters of glutamate-1 (VGluT1) and vesicular GABA transporter (VGAT) in three stress-sensitive regions of the brain (the medial pre-frontal cortex [mPFC], hippocampus, and amygdala).

Results:

Behaviorally, compared with the control group, adolescent chronic stress increased depression-like behaviors as shown in decreased sucrose preference (54.96 ± 1.97% vs. 43.11 ± 2.85%, t₍₂₂₎ = 3.417, P = 0.003) and reduced latency to immobility in the tail suspension test (92.77 ± 25.08 s vs. 33.14 ± 5.95 s, t₍₂₅₎ = 2.394, P = 0.025), but did not affect anxiety-like behaviors and pre-pulse inhibition. At the neurobiologic level, adolescent stress down-regulated PV⁺, not CR⁺, inter-neuron density in the mPFC (F_{(1, 39)} = 19.30, P < 0.001), and hippocampus (F_{(1, 42)} = 5.823, P = 0.020) and altered the CR⁺, not PV⁺, inter-neuron density in the amygdala (F_{(1, 28)} = 23.16, P < 0.001). The VGluT1/VGAT ratio was decreased in all three regions (all F > 10.09, all P < 0.004), which suggests stress-induced hypoexcitability in these regions.

Conclusions:

Chronic stress during adolescence increased depression-like behaviors in aged mice, which may be associated with the E/I imbalance in stress-sensitive brain regions.

Behavioral Abnormalities in Knockout and Humanized Tau Mice

Microtubule-associated protein tau assists in stabilizing microtubules and has been particularly implicated in Alzheimer's disease (AD). Given the importance of tau to AD pathogenesis and therapies, it is important to understand non-classic physiological functions for this protein inside and outside the central nervous system (CNS). Our group has previously shown that tau ablation triggers glucose intolerance and pancreatic dysfunction in mice, suggesting that tau plays a role in peripheral metabolic regulation. Little is known about the role of tau in anxiety. Moreover, inconsistent results have been generated regarding the effects of tau deletion in memory. Here, we characterize systemic insulin resistance, anxiety-related behavior and memory in 15 to 20 weeks old Wild-Type (WT), Tau knockout (TauKO) and a distinct hTau mouse model consisting of tau knockout expressing the longest isoform (2N4R) of a non-mutant WT human Tau protein under the prion promoter (hTau). Our findings demonstrate that tau deletion leads to anxiety-related behavior, impaired contextual and cued fear memory. The presence of a human Tau transgene did not ameliorate the phenotypes observed in animals lacking the mouse tau protein and it elicited impairments in learning, memory, and peripheral insulin sensitivity. Our results suggest that tau protein plays a role in memory and anxiety-related behavior. Our findings also indicate that previously unrecognized functions for tau protein may be a complicating factor in using animal models on the TauKO background. Understanding the link between tau pathophysiology and cognitive and metabolic alterations is of great importance to establish the complete contribution of tau protein to AD pathogenesis.

Depressive-Like Behaviors Induced by Chronic Social Defeat Stress Are Associated With HDAC7 Reduction in the Nucleus Accumbens

Persistent symptoms of depression indicate the adaptive involvement of stable molecules in the brain that may be manifested at the level of chromatin remodeling, such as histone acetylation. Former studies have identified alterations in histone acetylation and deacetylation in several animal models about depression. However, the specific histone deacetylases related with depression are needed to be explored. Here, social avoidance behaviors, anxiety-, and depression-like behaviors were all found in mice suffered from chronic social defeat stress. Moreover, we also discovered that the amount of the class II histone deacetylase, HDAC7 rather than HDAC2, was significantly decreased in the nucleus accumbens of defeated mice, which suggested that HDAC7 might be a crucial histone deacetylase in a chronic social defeat stress model. Our data showed that the depressive-like behaviors induced by chronic social defeat stress were associated with HDAC7 reduction in nucleus accumbens. HDAC7 might be a promising therapeutic target for depression.

Early Cognitive and Behavioral Deficits in Mouse Models for Tauopathy and Alzheimer's Disease

Neurocognitive disorders, among which Alzheimer's disease (AD), have become one of the major causes of death in developed countries. No effective disease-modifying therapy is available, possibly because current treatments are administered too late to still be able to intervene in the disease progress. AD is characterized by a gradual onset with subclinical neurobiological and behavioral changes that precede diagnosis with years to even decades. The earlier the diagnosis, the earlier potential treatments can be tested and started. Mouse models are valuable to study the possible causes underlying early phases of neuropathology and their reflection in behavior and other biomarkers, to help improve preclinical detection and diagnosis of AD. Here, we assessed cognitive functioning and social behavior in transgenic mice expressing tau pathology only (Tau-P301L) or a combination of amyloid and tau pathology [amyloid precursor protein (APP)-V717I × Tau-P301L]. The mice were subjected to a variety of behavioral tasks at an age of 3-6 months, i.e., at an early phase of their AD-like pathology. We hypothesized that compared to age-matched wild-type controls, transgenic mice would show specific impairments in both cognitive and non-cognitive tasks. In line with our expectations, transgenic mice showed decreased cognitive flexibility in the Morris water maze, decreased exploratory behavior, decreased performance in a nesting task, and increased anxiety-like behavior. In accordance with the amyloid-cascade hypothesis, some of the behavioral measures showed more severe deficits in APP-V717I × Tau-P301L compared to Tau-P301L mice, indicating an exacerbation of disease processes due to the co-occurrence of amyloid and tau pathology. Our study supports the use of behavioral markers as early indicators of ongoing AD pathology during the preclinical phase.

Antidepressant-Like Effect of β-Lactolin, a Glycine-Threonine-Tryptophan-Tyrosine Peptide

The number of patients with mental illnesses, including depression, is rapidly increasing, and daily lifestyle is closely associated with the development of symptoms. Consequently, corrective measures, such as diet-based treatment for diseases, are receiving great attention. We previously showed that β-lactolin, a β-lactopeptide of glycine-threonine-tryptophan-tyrosine peptide, inhibits monoamine oxidase and improves memory impairment in mice, but the effects on depression have not been investigated. Here we showed that β-lactolin improved depression-like behavior via dopamine-D1-like receptor. Orally administered β-lactolin reduced immobility time in tail suspension test (TST). Pretreatment with SCH23390, dopamine D1-like receptor antagonist, attenuated the reduction in TST by β-lactolin. These effects were observed by the treatment with whey digest rich in β-lactolin. In addition, β-lactolin increased the levels of dopamine in the frontal cortex associated with the depression-like behavior. The present study suggests that supplements or nutraceutical compounds in whey digests (such as β-lactolin) show antidepressant-like effect.

Using animal models to evaluate the functional consequences of anesthesia during early neurodevelopment

Fifteen years ago Olney and colleagues began using animal models to evaluate the effects of anesthetic and sedative agents (ASAs) on neurodevelopment. The results from ongoing studies indicate that, under certain conditions, exposure to these drugs during development induces an acute elevated apoptotic neurodegenerative response in the brain and long-term functional impairments. These animal models have played a significant role in bringing attention to the possible adverse effects of exposing the developing brain to ASAs when few concerns had been raised previously in the medical community. The apoptotic degenerative response resulting from neonatal exposure to ASAs has been replicated in many studies in both rodents and non-human primates, suggesting that a similar effect may occur in humans. In both rodents and non-human primates, significantly increased levels of apoptotic degeneration are often associated with functional impairments later in life. However, behavioral deficits following developmental ASA exposure have not been consistently reported even when significantly elevated levels of apoptotic degeneration have been documented in animal models. In the present work, we review this literature and propose a rodent model for assessing potential functional deficits following neonatal ASA exposure with special reference to experimental design and procedural issues. Our intent is to improve test sensitivity and replicability for detecting subtle behavioral effects, and thus enhance the translational significance of ASA models.

Chronic Stress Induces Activity, Synaptic, and Transcriptional Remodeling of the Lateral Habenula Associated with Deficits in Motivated Behaviors

Chronic stress (CS) is a major risk factor for the development of depression. Here, we demonstrate that CS-induced hyperactivity in ventral tegmental area (VTA)-projecting lateral habenula (LHb) neurons is associated with increased passive coping (PC), but not anxiety or anhedonia. LHb→VTA neurons in mice with increased PC show increased burst and tonic firing as well as synaptic adaptations in excitatory inputs from the entopeduncular nucleus (EP). In vivo manipulations of EP→LHb or LHb→VTA neurons selectively alter PC and effort-related motivation. Conversely, dorsal raphe (DR)-projecting LHb neurons do not show CS-induced hyperactivity and are targeted indirectly by the EP. Using single-cell transcriptomics, we reveal a set of genes that can collectively serve as biomarkers to identify mice with increased PC and differentiate LHb→VTA from LHb→DR neurons. Together, we provide a set of biological markers at the level of genes, synapses, cells, and circuits that define a distinctive CS-induced behavioral phenotype.

Oral selective serotonin reuptake inhibitors activate vagus nerve dependent gut-brain signalling

The vagus nerve can transmit signals to the brain resulting in a reduction in depressive behavior as evidenced by the long-term beneficial effects of electrical stimulation of the vagus in patients with intractable depression. The vagus is the major neural connection between gut and brain, and we have previously shown that ingestion of beneficial bacteria modulates behaviour and brain neurochemistry via this pathway. Given the high levels of serotonin in the gut, we considered if gut-brain signaling, and specifically the vagal pathway, might contribute to the therapeutic effect of oral selective serotonin reuptake inhibitors (SSRI). Mesenteric nerve recordings were conducted in mice after treatment with SSRI to ascertain if this class of drugs resulted in increased vagal excitability. Patch clamp recordings of enteric neurons were carried out to measure activity of primary afferent neurons in the gut in response to SSRI and to assess the importance of gut epithelium in transducing signal. The tail suspension test (TST) was used following 14d feeding of SSRI in vagotomised and surgical sham mice to measure depressive-like behaviour. Brain mRNA expression was examined via PCR and the intestinal microbiome was assessed. Mesenteric nerve recordings in BALB/c mice demonstrated that oral treatment with SSRI leads to a significant increase in vagal activity. This effect was not observed in mice treated with a representative noradrenaline-dopamine reuptake inhibitor. It is known that signals from the gut can be transmitted to the vagus via the enteric nervous system. Exposure of the gut to SSRI increased the excitability of intrinsic primary afferent neurons in the myenteric plexus, through an intestinal epithelium dependent mechanism, and alpha-diversity of gut microbiota was altered. Critically, blocking vagal signaling from gut to brain, via subdiaphragmatic vagotomy, abolished the antidepressive effects of oral SSRI treatment as determined by the tail suspension test. This work suggests that vagus nerve dependent gut-brain signaling contributes to the effects of oral SSRI and further, highlights the potential for pharmacological approaches to treatment of mood disorders that focus on vagal stimulation and may not even require therapeutic agents to enter the circulation.

Lipocalin-2 is dispensable in inflammation-induced sickness and depression-like behavior

RATIONALE

While the relationship between inflammation and depression is well-established, the molecular mechanisms mediating this relationship remain unclear. RNA sequencing analysis comparing brains of vehicle- and lipopolysaccharide-treated mice revealed LCN2 among the most dysregulated genes. As LCN2 is known to be an important regulator of the immune response to bacterial infection, we investigated its role in the behavioral response to lipopolysaccharide.

OBJECTIVE

To explore the role of LCN2 in modulating behavior following lipopolysaccharide administration using wild type (WT) and lcn2-/- mice.

METHODS

Using a within-subjects design, mice were treated with 0.33 mg/kg liposaccharide (LPS) and vehicle. Primary outcome measures included body weight, food consumption, voluntary wheel running, sucrose preference, and the tail suspension test. To evaluate the inflammatory response, 1 week later, mice were re-administered either vehicle or LPS and terminated at 6 h.

RESULTS

While lcn2-/- mice had increased baseline food consumption and body weight, they showed a pattern of reduced food consumption and weight loss similar to WT mice in response to LPS. WT and lcn2-/- mice both recovered voluntary activity on the fourth day following LPS. LPS induced equivalent reductions in sucrose preference and TST immobility in the WT and lcn2-/- mice. Finally, there were no significant effects of genotype on inflammatory markers.

CONCLUSIONS

Our data demonstrate that lcn2 is dispensable for sterile inflammation-induced sickness and depression-like behavior. Specifically, lcn2-/- mice displayed sickness and immobility in the tail suspension test comparable to that of WT mice both in terms of intensity and duration.

Effects of the Novel IDO Inhibitor DWG-1036 on the Behavior of Male and Female 3xTg-AD Mice

The kynurenine pathway metabolizes tryptophan into nicotinamide adenine dinucleotide, producing a number of intermediary metabolites, including 3-hydroxy kynurenine and quinolinic acid, which are involved in the neurodegenerative mechanisms that underlie Alzheimer's disease (AD). Indolamine 2,3-dioxygenase (IDO), the first and rate-limiting enzyme of this pathway, is increased in AD, and it has been hypothesized that blocking this enzyme may slow the progression of AD. In this study, we treated male and female 3xTg-AD and wild-type mice with the novel IDO inhibitor DWG-1036 (80 mg/kg) or vehicle (distilled water) from 2 to 6 months of age and then tested them in a battery of behavioral tests that measured spatial learning and memory (Barnes maze), working memory (trace fear conditioning), motor coordination and learning (rotarod), anxiety (elevated plus maze), and depression (tail suspension test). The 3xTg-AD mice treated with DWG-1036 showed better memory in the trace fear conditioning task and significant improvements in learning but poorer spatial memory in the Barnes maze. DWG-1036 treatment also ameliorated the behaviors associated with increased anxiety in the elevated plus maze and depression-like behaviors in the tail suspension test in 3xTg-AD mice. However, the effects of DWG-1036 treatment on the behavioral tasks were variable, and sex differences were apparent. In addition, high doses of DWG-1036 resulted in reduced body weight, particularly in females. Taken together, our results suggest that the kynurenine pathway is a promising target for treating AD, but more work is needed to determine the effective compounds, examine sex differences, and understand the side effects of the compounds.

Leucine-Histidine Dipeptide Attenuates Microglial Activation and Emotional Disturbances Induced by Brain Inflammation and Repeated Social Defeat Stress

The number of patients with mental illnesses is rapidly increasing, and daily lifestyle is closely associated with the development of symptoms. It is suggested that inflammatory molecules derived from microglia play crucial roles for the pathophysiology of depression. In the present study, we discovered that leucine–histidine (LH) dipeptide suppressed activation of primary microglia. The effects of LH dipeptide orally administered were measured using tail suspension test (TST) in mice injected with lipopolysaccharide and social interaction test in mice received social defeat stress. LH dipeptide reduced pro-inflammatory cytokines upon stimulation in microglia. Orally administered LH dipeptide was delivered to the brain and suppressed the production of pro-inflammatory cytokines in the brain and concomitant depression-like behavior in the TST. Moreover, oral administration of LH dipeptide suppressed the induction of depression- and anxiety-like behaviors induced by repeated social defeat stress. These results indicate that LH dipeptide suppressed the activation of microglia and ameliorated depression-associated emotional disturbances. Further, we found that LH dipeptide was abundant in various fermented products. Together with previous epidemiological reports that daily intake of these fermented foods is negatively associated with the incidence of psychiatric diseases, our findings suggest that food rich in LH dipeptide may improve mental health.

Neonatal brain-directed gene therapy rescues a mouse model of neurodegenerative CLN6 Batten disease

The neuronal ceroid lipofuscinoses (NCLs), more commonly referred to as Batten disease, are a group of inherited lysosomal storage disorders that present with neurodegeneration, loss of vision and premature death. There are at least 13 genetically distinct forms of NCL. Enzyme replacement therapies and pre-clinical studies on gene supplementation have shown promising results for NCLs caused by lysosomal enzyme deficiencies. The development of gene therapies targeting the brain for NCLs caused by defects in transmembrane proteins has been more challenging and only limited therapeutic effects in animal models have been achieved so far. Here, we describe the development of an adeno-associated virus (AAV)-mediated gene therapy to treat the neurodegeneration in a mouse model of CLN6 disease, a form of NCL with a deficiency in the membrane-bound protein CLN6. We show that neonatal bilateral intracerebroventricular injections with AAV9 carrying CLN6 increase lifespan by more than 90%, maintain motor skills and motor coordination and reduce neuropathological hallmarks of Cln6-deficient mice up to 23 months post vector administration. These data demonstrate that brain-directed gene therapy is a valid strategy to treat the neurodegeneration of CLN6 disease and may be applied to other forms of NCL caused by transmembrane protein deficiencies in the future.

Sex differences in cued fear responses and parvalbumin cell density in the hippocampus following repetitive concussive brain injuries in C57BL/6J mice

There is strong evidence to suggest a link between repeated head trauma and cognitive and emotional disorders, and Repetitive concussive brain injuries (rCBI) may also be a risk factor for depression and anxiety disorders. Animal models of brain injury afford the opportunity for controlled study of the effects of injury on functional outcomes. In this study, male and cycling female C57BL/6J mice sustained rCBI (3x) at 24-hr intervals and were tested in a context and cued fear conditioning paradigm, open field (OF), elevated zero maze and tail suspension test. All mice with rCBI showed less freezing behavior than sham control mice during the fear conditioning context test. Injured male, but not female mice also froze less in response to the auditory cue (tone). Injured mice were hyperactive in an OF environment and spent more time in the open quadrants of the elevated zero maze, suggesting decreased anxiety, but there were no differences between injured mice and sham-controls in depressive-like activity on the tail suspension test. Pathologically, injured mice showed increased astrogliosis in the injured cortex and white matter tracts (optic tracts and corpus callosum). There were no changes in the number of parvalbumin-positive interneurons in the cortex or amygdala, but injured male mice had fewer parvalbumin-positive neurons in the hippocampus. Parvalbumin-reactive interneurons of the hippocampus have been previously demonstrated to be involved in hippocampal-cortical interactions required for memory consolidation, and it is possible memory changes in the fear-conditioning paradigm following rCBI are the result of more subtle imbalances in excitation and inhibition both within the amygdala and hippocampus, and between more widespread brain regions that are injured following a diffuse brain injury.

2,3,5,4'-Tetrahydroxystilbene-2-O-β-d-glucoside attenuates MPP+/MPTP-induced neurotoxicity in vitro and in vivo by restoring the BDNF-TrkB and FGF2-Akt signaling axis and inhibition of apoptosis

The major bioactive ingredient THSG of Polygonum multiflorum is well established for its anti-oxidation, anti-aging and anti-inflammation properties. Increasing evidence supports the capacity of THSG to ameliorate the biochemistry of neurotrophins and their downstream signaling axis in mouse models to attenuate neurodegenerative diseases such as Alzheimer's and Parkinson's disease. In this study, the neuroprotective effects of THSG were studied in vitro and in vivo. In cultured mesencephalic dopamine neurons and SH-SY5Y cell line, it was found that THSG protected the integrity of the cell body and neurite branching from MPP+-induced toxicity by restoring the expression of FGF2 and BDNF and their downstream signaling pathways to inhibit apoptosis and promote cell survival. The inhibition of Akt signaling by LY294002 or TrkB activity by K252a eliminated the neuroprotective effects of THSG. In the MPTP-induced mouse models of Parkinson's disease, THSG ameliorated the animal behaviors against MPTP-induced neurotoxicity, which was demonstrated by the pole test and the tail suspension test. Biochemical and immunohistochemical analysis verified the THSG-mediated restoration of the FGF2-Akt and BDNF-TrkB signaling axis in the substantia nigra and corpus striatum and the recovery of dopaminergic neurons. These results establish the neuroprotective effects of THSG in vitro and in vivo and unravel the underlying mechanism against toxin-induced neural atrophy, providing a new avenue for the use and pharmacological research of edible medicine for anti-neurodegenerative diseases.

Interferon-α exacerbates neuropsychiatric phenotypes in lupus-prone mice

Background

Neuropsychiatric systemic lupus erythaematosus (NP-SLE) is one of the major manifestations of lupus. However, the mechanisms involved in NP-SLE are still largely unknown. The abnormal activation of the type I IFN signalling pathway is involved in SLE pathogenesis and is linked to NP-SLE, but the effect of IFN-α on NP-SLE encephalopathy has not been systematically studied.

Methods

An intravenous injection of Adv-IFN-α (10 mice, 10 × 10⁹ vp) was administered to the IFN-α-treated group, and Adv-ctrl (10 mice, 10 × 10⁹ vp) (ViGene Biosciences, China) was administered to the control group. Gene expression was determined by real-time quantitative polymerase chain reaction (RT-qPCR). Enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies in the serum, and urinary protein levels were measured with a BCA Protein Assay kit. Haematoxylin-eosin (H&E) and periodic acid-Schiff (PAS)-light green staining were used for kidney histology. The elevated plus-maze test, novelty-suppressed feeding assay, open-field test, tail suspension test, social dominance tube test, three-chamber social interaction test, step-down passive avoidance test and novelty Y-maze task were used to assess behaviour.

Results

In this study, we performed a series of behavioural tests to assess the neuropsychiatric phenotypes of IFN-α-treated NZB/NZW F1 mice and found that these mice developed a series of mental disorders such as anxiety-like phenotypes, depression-like phenotypes, deficits in sociability and cognitive impairments, which mimic the neuropsychiatric manifestations of NP-SLE, with a consistent onset and progression.

Conclusions

Our research verified that IFN-α plays a critical role in NP-SLE and provides a comprehensive NP-SLE mouse model for dissecting the mechanisms of NP-SLE and developing novel therapies for intervention.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1985-9) contains supplementary material, which is available to authorized users.

Sasa Quelpaertensis Nakai Induced Antidepressant-Like Effect in Ovariectomized Rats

Background

Sasa quelpaertensis Nakai extract (SQE) or dwarf bamboo has been extensively investigated for its antioxidant and anti-inflammatory effects; however, no previous study assessed its effect as an antidepressant agent. Therefore, this study was designed to examine the effect of oral SQE administration in ameliorating menopausal depressive symptoms and to evaluate its mechanisms in ovariectomized rats with repeated stress.

Methods

All experimental groups except normal group underwent ovariectomy and then immobilization for 14 consecutive days. During these 2 weeks, two rat groups received SQE (100 and 300 mg/kg orally) and their cutaneous body temperature was measured. The tail suspension test (TST) and forced swim test (FST) were performed in order to evaluate depression-like behavior. Additionally, enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry were carried out to evaluate the central monoaminergic neurotransmitter levels and activity.

Results

Oral SQE (100 mg/kg) administration had reduced immobility time in TST and FST. Additionally, the SQE 100 and 300 mg/kg administration had decreased the cutaneous body temperature in the rats compared to those without treatment. In ELISA analysis, the SQE 100 group expressed elevated levels of serotonin and dopamine in the hypothalamus, prefrontal cortex, and hippocampus. Antityrosine hydroxylase (anti-TH) antibodies showed a tremendous increase in the density of TH positive cells in the locus coeruleus (LC) region of the SQE 100 group. Likewise, the SQE 100 elevated the number of tryptophan hydroxylase (TPH) and protein kinase C (PKC) immunoreactive cell counts and density in the hypothalamic region.

Conclusion

These results suggested that the oral SQE administration induced the antidepressant-like effect in the ovariectomized rats with repeated stress via upregulating the levels of serotonin and dopamine through enhancing the expression of TH, TPH, and PKC in many brain areas.

Selegiline Recovers Synaptic Plasticity in the Medial Prefrontal Cortex and Improves Corresponding Depression-Like Behavior in a Mouse Model of Parkinson's Disease

In patients with Parkinson’s disease (PD), non-motor symptoms (NMS) including depression and anxiety are often recognized before motor symptoms develop. Monoamine oxidase (MAO)-B inhibitors are therapeutically effective for motor symptoms; however, their effects on NMS in PD are yet to be fully assessed. Here, we aimed to explore the antidepressant-like effects of propargyl MAO-B inhibitors, selegiline and rasagiline, in mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) as a PD model, and to elucidate the mechanisms underlying these effects. Four repeated intraperitoneal injections of MPTP at 17.5 mg/kg to C57BL/6 mice led to a partial reduction in the number of nigrostriatal tyrosine hydroxylase-positive neurons and to the extension of immobility time during the tail suspension test (TST), without any obvious induction of motor deficits. A single subcutaneous administration of selegiline at 10 mg/kg shortened the extended immobility time of MPTP mice in the TST, without any increase in motor activities, suggesting that selegiline exerts antidepressant-like effects. In this test, rasagiline did not produce antidepressant-like effects, although the inhibitory effect of 3 mg/kg rasagiline on brain MAO activity was comparable to that of 10 mg/kg selegiline. The shortened immobility time in the TST correlated with reduced cortical dopamine (DA) turnover rates in MPTP mice treated with selegiline, but not in MPTP mice treated with rasagiline. These results suggest that MAO inhibition does not entirely account for the antidepressant-like effects of selegiline. Administration of selegiline (10 mg/kg), but not rasagiline (1 mg/kg), to MPTP mice restored the impaired long-term potentiation induced by high-frequency stimulation in the medial prefrontal cortex (mPFC), and normalized the reduced phosphorylation of Ca²⁺/calmodulin-dependent protein kinase IIα, which is known to be involved in neuroplasticity, in the frontal cortex. In MPTP mice, the antiparkinsonian drug pramipexole (0.3 mg/kg), a DA D₂ and D₃ receptor agonist, that has been shown to be effective in treating depression in PD, ameliorated depression-like behavior and synaptic dysfunction in the mPFC. Taken together, the antidepressant-like effects of selegiline in MPTP mice are attributable to the restoration of impaired synaptic plasticity in the mPFC, suggesting its potential for treating depression in early PD.

Astrogliosis Associated With Behavioral Abnormality in a Non-anaphylactic Mouse Model of Cow's Milk Allergy

Etiology of neuropsychiatric disorders is complex, involving multiple factors that can affect the type and severity of symptoms. Although precise causes are far from being identified, allergy or other forms of hypersensitivity to dietary ingredients have been implicated in triggering or worsening of behavioral and emotional symptoms, especially in patients suffering from depression, anxiety, attention-deficit hyperactivity, and/or autism. Among such ingredients, cow's milk, along with wheat gluten, is commonly suspected. However, the contributory role of cow's milk in these disorders has not been elucidated due to insufficient pathophysiological evidence. In the present study, we therefore investigated neuroinflammatory changes that are associated with behavioral abnormality using a non-anaphylactic mouse model of cow's milk allergy (CMA). Male and female C57BL/6J mice were subjected to a 5-week oral sensitization procedure without or with a major milk allergen, beta-lactoglobulin (BLG). All mice were then later challenged with BLG, and their anxiety- and depression-associated behaviors were subsequently assessed during the 6th and 7th weeks. We found that BLG-sensitized male mice exhibited significantly increased anxiety- and depression-like behavior, although they did not display anaphylactic reactions when challenged with BLG. Female behavior was not noticeably affected by BLG sensitization. Upon examination of the small intestines, reduced immunoreactivity to occludin was detected in the ileal mucosa of BLG-sensitized mice although the transcriptional expression of this tight-junction protein was not significantly altered when measured by quantitative RT-PCR. On the other hand, the expression of tumor necrosis factor alpha (TNFα) in the ileal mucosa was significantly elevated in BLG-sensitized mice, suggesting the sensitization had resulted in intestinal inflammation. Inflammatory responses were also detected in the brain of BLG-sensitized mice, determined by the hypertrophic morphology of GFAP-immunoreactive astrocytes. These reactive astrocytes were particularly evident near the blood vessels in the midbrain region, resembling the perivascular barrier previously reported by others in experimental autoimmune encephalitis (EAE) mouse models. Interestingly, increased levels of COX-2 and TNFα were also found in this region. Taken together, our results demonstrated that BLG sensitization elicits inflammatory responses in the intestine and brain without overt anaphylactic signs of milk allergy, signifying food allergy as a potential pathogenic factor of neuropsychiatric disorders.

Adult Pgf-/- mice behaviour and neuroanatomy are altered by neonatal treatment with recombinant placental growth factor

Offspring of preeclamptic pregnancies have cognitive alterations. Placental growth factor (PGF), is low in preeclampsia; reduced levels may affect brain development. PGF-null mice differ from normal congenic controls in cerebrovasculature, neuroanatomy and behavior. Using brain imaging and behavioral testing, we asked whether developmentally asynchronous (i.e. neonatal) PGF supplementation alters the vascular, neuroanatomic and/or behavioral status of Pgf^−/− mice at adulthood. C57BL/6-Pgf^−/− pups were treated intraperitoneally on postnatal days 1–10 with vehicle or PGF at 10 pg/g, 70 pg/g or 700 pg/g. These mice underwent behavioral testing and perfusion for MRI and analysis of retinal vasculature. A second cohort of vehicle- or PGF-treated mice was perfused for micro-CT imaging. 10 pg/g PGF-treated mice exhibited less locomotor activity and greater anxiety-like behavior relative to vehicle-treated mice. Depressive-like behavior showed a sex-specific, dose-dependent decrease and was lowest in 700 pg/g PGF-treated females relative to vehicle-treated females. Spatial learning did not differ. MRI revealed smaller volume of three structures in the 10 pg/g group, larger volume of seven structures in the 70 pg/g group and smaller volume of one structure in the 700 pg/g group. No cerebral or retinal vascular differences were detected. Overall, neonatal PGF replacement altered behavior and neuroanatomy of adult Pgf^−/− mice.

Metformin treatment reduces motor and neuropsychiatric phenotypes in the zQ175 mouse model of Huntington disease

Huntington disease is a neurodegenerative condition for which there is no cure to date. Activation of AMP-activated protein kinase has previously been shown to be beneficial in in vitro and in vivo models of Huntington’s disease. Moreover, a recent cross-sectional study demonstrated that treatment with metformin, a well-known activator of this enzyme, is associated with better cognitive scores in patients with this disease. We performed a preclinical study using metformin to treat phenotypes of the zQ175 mouse model of Huntington disease. We evaluated behavior (motor and neuropsychiatric function) and molecular phenotypes (aggregation of mutant huntingtin, levels of brain-derived neurotrophic factor, neuronal inflammation, etc.). We also used two models of polyglutamine toxicity in Caenorhabditis elegans to further explore potential mechanisms of metformin action. Our results provide strong evidence that metformin alleviates motor and neuropsychiatric phenotypes in zQ175 mice. Moreover, metformin intake reduces the number of nuclear aggregates of mutant huntingtin in the striatum. The expression of brain-derived neurotrophic factor, which is reduced in mutant animals, is partially restored in metformin-treated mice, and glial activation in mutant mice is reduced in metformin-treated animals. In addition, using worm models of polyglutamine toxicity, we demonstrate that metformin reduces polyglutamine aggregates and restores neuronal function through mechanisms involving AMP-activated protein kinase and lysosomal function. Our data indicate that metformin alleviates the progression of the disease and further supports AMP-activated protein kinase as a druggable target against Huntington’s disease.

Metformin, an existing drug for diabetes, shows promise in alleviating symptoms of early Huntington’s disease in mouse models. Huntington’s disease is a genetic disorder that results in the gradual deterioration of motor skills and cognitive ability. It is caused by a defect in a single gene that then encodes a mutant huntingtin protein, which aggregates and kills brain cells. Growing observational evidence suggests that patients undergoing metformin treatment for diabetes type II exhibit fewer symptoms of age-related disease, as well as Huntington’s disease. Rafael Vázquez-Manrique at Hospital Universitario y Politécnico La Fe, València and Pascual Sanz at IBV-CSIC and CIBERER, València, and scientists across Spain used metformin to treat motor and neuropsychiatric symptoms in a Huntington’s mouse model. They found that metformin alleviated symptoms by actively reducing huntingtin levels, dispersing aggregations and limiting brain inflammation.

Role of Tryptophan in Microbiota-Induced Depressive-Like Behavior: Evidence From Tryptophan Depletion Study

During the past decade, there has been a substantial rise in the knowledge about the effects of gut microbiota on host physiology and behavior, including depressive behavior. Initial studies determined that gut microbiota can regulate host tryptophan levels, which is a main serotonin precursor. A dysfunctional serotonergic system is considered to be one of the main factors contributing to the development of depression. Therefore, we hypothesized that regulation of brain tryptophan and serotonin can explain, at least partly, the effects of microbiota on depressive behavior. To test this hypothesis, we examined depressive-like behavior and brain levels of serotonin and tryptophan, of germ free (GF) and specific-pathogen free (SPF) mice under basal conditions, or after acute tryptophan depletion (ATD) procedure, which is a method to decrease tryptophan and serotonin levels in the brain. In basal conditions, GF mice exhibited less depressive-like behavior in sucrose preference, tail-suspension and forced swim tests, compared to SPF mice. In addition, in mice that were not subjected to ATD, GF mice displayed higher levels of tryptophan, serotonin and 5-hydroxyindoleacetic acid (the main degradation product of serotonin) in medial prefrontal cortex (mPFC) and hippocampus (HIPPO), compared to SPF mice. Interestingly, ATD increased depressive-like behavior of GF, but not of SPF mice. These behavioral changes were accompanied by a stronger reduction of tryptophan, serotonin and 5-hydroxyindoleacetic acid in mPFC and HIPPO in GF mice after ATD, when compared to SPF mice. Therefore, the serotonergic system of GF mice is more vulnerable to the acute challenge of tryptophan reduction, and GF mice after tryptophan reduction behave more similarly to SPF mice. These data provide functional evidence that microbiota affects depression-like behavior through influencing brain tryptophan accessibility and the serotonergic system.

Contrasting characteristic behaviours among common laboratory mouse strains

Mice are widely used to model wide-ranging human neurological disorders, from development to degenerative pathophysiology. Behavioural and molecular characteristics of these mouse models are influenced by the genetic background of each strain. Among the most commonly used strains, the inbred C57BL/6J, BALB/c, CBA and 129SvEv lines and the CD1 outbred line are particularly predominant. Despite their prevalence, comparative performance of these strains on many standard behavioural tests commonly used to assess neurological conditions remains diffusely and indirectly accessible in the literature. Given that independent studies may be conducted with mice of differing genetic backgrounds, any variation in characteristic behavioural responses of specific strains should be delineated in order to properly interpret results among studies. Thus, in the present study, we aimed to characterize these commonly used mice strains through several standard behavioural tests. Here, we found that animals from different genetic background strains exhibited varying behavioural patterns when assessed for sociability/novelty, memory function, and negative behaviours like despair and stress calls. These results suggest that genetic variation among strains may be responsible-in part-for strain-specific behavioural phenotypes and potential predisposition to some neurological disorders.

Chronic Neurobehavioral Sex Differences in a Murine Model of Repetitive Concussive Brain Injury

Traumatic brain injury (TBI) resulting from repeated head trauma is frequently characterized by diffuse axonal injury and long-term motor, cognitive and neuropsychiatric symptoms. Given the delay, often decades, between repeated head traumas and the presentation of symptoms in TBI patients, animal models of repeated injuries should be studied longitudinally to properly assess the longer-term effects of multiple concussive injuries on functional outcomes. In this study, male and cycling female C57BL/6J mice underwent repeated (three) concussive brain injuries (rCBI) delivered via a Leica ImpactOne cortical impact device and were assessed chronically on motor (open field and rotarod), cognitive (y-maze and active place avoidance), and neuropsychiatric (marble-burying, elevated zero maze and tail suspension) tests. Motor deficits were significant on the rotarod on the day following the injuries, and slight impairment remained for up to 6 months. All mice that sustained rCBI had significant cognitive deficits on the active place avoidance test and showed greater agitation (less immobility) in the tail suspension test. Only injured male mice were significantly hyperactive in the open field, and had increased time spent in the open quadrants of the elevated zero maze. One year after the injuries, mice of both sexes exhibited persistent pathological changes by the presence of Prussian blue staining (indication of prior microbleeds), primarily in the cortex at the site of the injury, and increased GFAP staining in the perilesional cortex and axonal tracts (corpus callosum and optic tracts). These data demonstrate that a pathological phenotype with motor, cognitive, and neuropsychiatric symptoms can be observed in an animal model of rCBI for at least one year post-injury, providing a pre-clinical setting for the study of the link between multiple brain injuries and neurodegenerative disorders. Furthermore, this is the first study to include both sexes in a pre-clinical long-term rCBI model, and female mice are less impaired functionally than males.

Fluid supplementation accelerates epithelial repair during chemical colitis

The dextran sulfate sodium (DSS) model of colitis is a common animal model of inflammatory bowel disease that causes pain and distress. In this study, we aimed to determine whether fluid supplementation can be used as a welfare-based intervention to minimize animal suffering. C57Bl/6 females undergoing acute colitis by administration of 3% DSS in drinking water were supplemented with 1 mL intraperitoneal injections of NaCl and compared to non-supplemented control mice. Mouse behavior and locomotive activity were assessed on days 5–6 after DSS initiation by means of tail suspension, novel object recognition and open field activity tests. Mice were euthanized after either the acute (day 7) or the recovery phase (day 12) of colitis and inflammation, epithelial proliferation, and differentiation were assessed by means of histology, immunohistochemistry, quantitative PCR, and western blot. We found that fluid-supplemented mice had reduced signs of colitis with no alterations in behavior or locomotive activity. Furthermore, we observed an accelerated epithelial repair response after fluid hydration during the acute phase of colitis, characterized by increased crypt proliferation, activation of ERK1/2, and modulation of TGF-β1 expression. Consistent with these findings, fluid-supplemented mice had increased numbers of goblet cells, upregulated expression of differentiation markers for absorptive enterocytes, and reduced inflammation during the recovery phase. Our results show that fluid hydration does not reduce stress in DSS-treated mice but alters colitis evolution by reducing clinical signs and accelerating epithelial repair. These results argue against the routine use of fluid supplementation in DSS-treated mice.

Depression, anxiety-like behavior, and memory impairment in mice exposed to chitosan-coated zein nanoparticles

The advent of biotechnology provided the synthesis of nanoproducts with diverse applications in the field of medicine, agriculture, food, among others. However, the toxicity of many nanoparticles (NP) currently used, which can penetrate natural systems and impact organisms, is not known. Thus, in this study, we evaluated whether the short exposure (5 days) to low concentrations of chitosan-coated zein nanoparticles (ZNP-CS) (0.2 ng/kg, 40 ng/kg, and 400.00 ng/kg) was capable of causing behavioral alterations compatible with cognitive deficit, as well as anxiety and depression-like behavior in Swiss mice. However, we observed an anxiogenic effect in the animals exposed to the highest ZNP-CS concentration (400.00 ng/kg), without locomotor alterations suggestive of sedation or hyperactivity in the elevated plus maze (EPM) test. We also observed that the ZNP-CS caused depressive-like behavior, indicated by the longer immobile time in the tail suspension test and the animals exposed to ZNP-CS presented deficit in recognition of the new object, not related to locomotor alteration in this test. To the best of our knowledge, this is the first report of the neurotoxicity of ZNP in a mammal animal model, contributing to the biological safety assessment of these nanocomposites.

Effects of Memantine in a Mouse Model of Postoperative Cognitive Dysfunction

Persistent impairment in cognitive functioning postoperatively is reported by clinical and animal studies, and is labeled as postoperative cognitive dysfunction (POCD). Evidence points to an exaggerated neuroinflammatory response resulting from peripheral systemic inflammation after surgery, with subsequent cytokine-induced glutamatergic excitotoxicity and synaptic impairment. These immunological changes, among many others, are also observed in Alzheimer’s disease. Memantine is an N-methyl-D-aspartate receptor (NMDAR) antagonist commonly used to treat Alzheimer’s disease. Surprisingly, little research exists on the role of memantine in preventing POCD. The purpose of this study is to investigate the effects of memantine on a spectrum of cognitive functions postoperatively. Mice were divided into 3 groups and each received treatment for 4 weeks. Placebo groups received a placebo then underwent either a sham procedure or a laparotomy procedure. The memantine group received memantine hydrochloride then underwent a laparotomy procedure. Cognitive tests were performed on postoperative days (POD) 1 and 7. Compared to sham-operated mice, placebo groups that underwent a laparotomy procedure showed impaired memory in the Morris water maze test, higher anxiety-like behavior in the open field and the elevated plus maze tests, increased depression-like behavior in the tail suspension test, and lack of preference for social novelty in the three-chamber test. On the other hand, memantine-treated mice that underwent a laparotomy procedure showed enhanced memory on POD7, improved depression-like behavior on POD1 and POD7, enhanced preference for social novelty on POD1, and no improvement in anxiety-like behavior. These findings suggest a potential protective effect of memantine in mice postoperatively on memory, depression-like behavior, and preference for social novelty.

Social Memory and Social Patterns Alterations in the Absence of STriatal-Enriched Protein Tyrosine Phosphatase

STriatal-Enriched protein tyrosine Phosphatase (STEP) is a neural-specific protein that opposes the development of synaptic strengthening and whose levels are altered in several neurodegenerative and psychiatric disorders. Since STEP is expressed in brain regions implicated in social behavior, namely the striatum, the CA2 region of the hippocampus, cortex and amygdala, here we investigated whether social memory and social patterns were altered in STEP knockout (KO) mice. Our data robustly demonstrated that STEP KO mice presented specific social memory impairment as indicated by the three-chamber sociability test, the social discrimination test, the 11-trial habituation/dishabituation social recognition test, and the novel object recognition test (NORT). This affectation was not related to deficiencies in the detection of social olfactory cues, altered sociability or anxiety levels. However, STEP KO mice showed lower exploratory activity, reduced interaction time with an intruder, less dominant behavior and higher immobility time in the tail suspension test than controls, suggesting alterations in motivation. Moreover, the extracellular levels of dopamine (DA), but not serotonin (5-HT), were increased in the dorsal striatum of STEP KO mice. Overall, our results indicate that STEP deficiency disrupts social memory and other social behaviors as well as DA homeostasis in the dorsal striatum.

Loss of the interaction between estradiol and insulin-like growth factor I in brain endothelial cells associates to changes in mood homeostasis during peri-menopause in mice

We recently reported that exercise increases resilience to stress in young female mice. Underlying mechanisms include an interaction of the ovarian hormone estradiol (E2) with insulin-like growth factor I (IGF-I), and an increase in the hippocampal levels of the latter. Since changes in mood regulation during aging may contribute to increasing incidence of affective disorders at older age, we determined whether the protective actions of exercise are maintained at later ages. We found that during peri-menopause, exercise no longer improves resilience to stress and even becomes anxiogenic. Furthermore, the interaction seen in young females between the E2 α receptor (ERα) and the IGF-I receptor (IGF-IR) is lost at middle-age. In addition, E2 no longer induces IGF-I uptake by brain endothelial cells, and consequently, hippocampal IGF-I levels do not increase. Treatment of middle-aged females with an ERα agonist did not recover the positive actions of exercise. Collectively, these data indicate that the loss of action of exercise during peri-menopause may be related to a loss of the interaction of IGF-IR with ERα in brain endothelial cells that cannot be ameliorated by estrogen therapy. Changes in regulation of mood by physical activity may contribute to increased appearance of affective disorders along age.

Bipolar Disorder: Its Etiology and How to Model in Rodents

Characterized by the switch of manic and depressive phases, bipolar disorder was described as early as the fifth century BC. Nevertheless up to date, the underlying neurobiology is still largely unclear, assuming a multifactor genesis with both biological-genetic and psychosocial factors. Significant process has been achieved in recent years in researching the causes of bipolar disorder with modern molecular biological (e.g., genetic and epigenetic studies) and imaging techniques (e.g., positron emission tomography (PET) and functional magnetic resonance imaging (fMRI)). In this chapter we will first summarize our recent knowledge on the etiology of bipolar disorder. We then discuss how several factors observed to contribute to bipolar disorder in human patients can be manipulated to generate rodent models for bipolar disorder. Finally, we will give an overview on behavioral test that can be used to assess bipolar-disorder-like behavior in rodents.

Opposing effects of S-equol supplementation on metabolic and behavioral parameters in mice fed a high-fat diet

Phytoestrogens, such as daidzein and genistein, may be used to treat various hormone-dependent disorders. Daidzein can be metabolized by intestinal microbes to S-equol. However, not all individuals possess bacteria producing this metabolite, resulting in categorization of equol vs nonequol producers. Past human and rodent studies have suggested that supplementation of this compound might yield beneficial metabolic and behavioral effects. We hypothesized that administration of S-equol to diet-induced obese male and female mice would mitigate potential diet-induced metabolic and comorbid neurobehavioral disorders. To test this possibility, we placed 5-week-old C57 mice on a high-fat diet (HFD) to mimic the diet currently consumed by many Western adults. Animals were randomly assigned to S-equol supplementation (10 mg/kg body weight) or vehicle control group. After 4 weeks on HFD with or without S-equol supplementation, metabolic and behavioral phenotyping was performed. Although the initial hypothesis proposed that S-equol treatment would improve metabolic and neurobehavioral outcomes, this supplementation instead exacerbated aspects of HFD-induced metabolic disease, as indicated by suppressed physical activity in treated individuals, reduced energy expenditure in treated males, and serum chemistry changes (hyperglycemia in treated individuals; hyperinsulinemia and hypoleptinemia in treated males). Conversely, S-equol individuals exhibited less anxiety-like and depressive-like behaviors, as evidenced by increased exploratory time in the elevated plus maze by treated males and increased time spent mobile in the tail suspension test for treated individuals. In summary, S-equol may be beneficial in mitigating depression and anxiety disorders in individuals, but for indeterminate reasons, supplementation may worsen facets of metabolic disorders in obese individuals.