Targeted Metabolomic Pathway Analysis and Validation Revealed Glutamatergic Disorder in the Prefrontal Cortex among the Chronic Social Defeat Stress Mice Model of Depression

Developmental exposure to arsenic reduces anxiety levels and leads to a depressive-like behavior in female offspring rats: Molecular changes in the prefrontal cortex

Exposure to inorganic arsenic (iAs) detrimentally affects the structure and function of the central nervous system. In-utero and postnatal exposure to iAs has been connected to adverse effects on cognitive development. Therefore, this investigation explores neurobehavioral and neurochemical effects of 0.05 and 0.10 mg/L iAs exposure during gestation and lactation periods on 90-day-old female offspring rats. The assessment of anxiety- and depressive-like behaviors was conducted through the application of an elevated plus maze and a forced swim test. The neurochemical changes were evaluated in the prefrontal cortex (PFC) through the determination of enzyme activities and α1 GABAA subunit expression levels. Our findings revealed a notable impact of iAs exposure on anxiety and the induction of depressive-like behavior in 90-day-old female offspring. Furthermore, the antioxidant status within the PFC exhibited discernible alterations in exposed rats. Notably, the activities of acetylcholinesterase and glutamate pyruvate transaminase demonstrated an increase, while glutamate oxaloacetate transaminase activity displayed a decrease within the PFC due to the iAs treatment. Additionally, a distinct downregulation in the mRNA expression of the α1GABAA receptor was observed in this neuronal region. These findings strongly suggest that iAs exposure during early stages of rat development causes significant modifications in brain oxidative stress markers and perturbs the activity of enzymes associated with cholinergic and glutamatergic systems. In parallel, it elicits a discernible reduction in the level of GABA receptors within the PFC. These molecular alterations may play a role in the diminished anxiety levels and the depressive-like behavior outlined in the current investigation.

Metabolomics in Depression: What We Learn from Preclinical and Clinical Evidences

Depression is one of the predominant common mental illnesses that affects millions of people of all ages worldwide. Random mood changes, loss of interest in routine activities, and prevalent unpleasant senses often characterize this common depreciated mental illness. Subjects with depressive disorders have a likelihood of developing cardiovascular complications, diabesity, and stroke. The exact genesis and pathogenesis of this disease are still questionable. A significant proportion of subjects with clinical depression display inadequate response to antidepressant therapies. Hence, clinicians often face challenges in predicting the treatment response. Emerging reports have indicated the association of depression with metabolic alterations. Metabolomics is one of the promising approaches that can offer fresh perspectives into the diagnosis, treatment, and prognosis of depression at the metabolic level. Despite numerous studies exploring metabolite profiles post-pharmacological interventions, a quantitative understanding of consistently altered metabolites is not yet established. The article gives a brief discussion on different biomarkers in depression and the degree to which biomarkers can improve treatment outcomes. In this review article, we have systemically reviewed the role of metabolomics in depression along with current challenges and future perspectives.

The bidirectional relationship of depression and disturbances in B cell homeostasis: Double trouble

Major depressive disorder (MDD) is a recurrent, persistent, and debilitating neuropsychiatric syndrome with an increasing morbidity and mortality, representing the leading cause of disability worldwide. The dysregulation of immune systems (including innate and adaptive immune systems) has been identified as one of the key contributing factors in the progression of MDD. As the main force of the humoral immunity, B cells have an essential role in the defense against infections, antitumor immunity and autoimmune diseases. Several recent studies have suggested an intriguing connection between disturbances in B cell homeostasis and the pathogenesis of MDD, however, the B-cell-dependent mechanism of MDD remains largely unexplored compared to other immune cells. In this review, we provide an overview of how B cell abnormality regulates the progression of MMD and the potential consequence of the disruption of B cell homeostasis in patients with MDD. Abnormalities of B-cell homeostasis not only promote susceptibility to MDD, but also lead to an increased risk of developing infection, malignancy and autoimmune diseases in patients with MDD. A better understanding of the contribution of B cells underlying MDD would provide opportunities for identification of more targeted treatment approaches and might provide an overall therapeutic benefit to improve the long-term outcomes of patients with MDD.

Shenyu ningshen tablet reduced neuronal damage in the hippocampus of chronic restraint stress model rat by inhibiting A1-reactive astrocytes

Context

Shenyu Ningshen (SYNS) tablet is the first pure Chinese medicinal small compound preparation approved for clinical trials for the treatment of depression in China. Clinical experiments confirmed that the formulation had a significant Improvement effect against depression due to the deficiency of both qi and yin. It has been shown to exhibit noticeable anti-inflammatory effect in an animal model of depression. Our previous study showed that SYNS could effectively inhibit the inflammatory response in a depression model.

Aim of the study

The purpose of this study was to investigate the protective effects of SYNS on neurons and explore whether the underlying mechanism was associated with A1s.

Materials and methods

The depression model of solitary raising-chronic restraint stress (CRS) rats was established; body weight examination, sugar water preference test, open field test, and histological analysis were performed to preliminarily verify the efficacy of the formulation. Subsequently, neuronal nucleus (NeuN) and synaptic-associated proteins (MAP2 and PSD95) were labeled, and the protective effect of SYNS on hippocampal neurons was observed based on the fluorescence intensity of the above indicators. Western blotting, histological examination, and immunofluorescence were used to evaluate the inhibitory effects of SYNS on neuroinflammation and activation of A1s in CRS depression model.

Results

SYNS improved behavioral indicators such as weight loss, pleasure loss, and reduced exercise volume in CRS rat model. SYNS restored the CRS-induced histopathological changes in the hippocampus. SYNS showed a certain degree of protective effect on synapses. Further, SYNS inhibited the activation of A1s by inhibiting neuroinflammatory factors in the hippocampus.

Conclusion

Our results showed that SYNS had a certain degree of neuroprotective effect, which might be related to its inhibition of the inflammatory response and A1s.

Progress of depression mechanism based on Omics method

Depression is a very common disabling mental disorder, which is typically characterized by high rates of disability and mortality. Although research into the various mechanisms of depression was still underway, its physiopathology remains uncertain. The rapid developments in new technologies and the combined use of a variety of techniques will help to understand the pathogenesis of depression and explore effective treatment methods. In this review, we focus on the combination of proteomic and metabolomic approaches to analyze metabolites and proteins in animal models of depression induced by different modeling approaches, with the aim of broadening the understanding of the physiopathological mechanisms of depression using complementary "omics" strategy.

Biomarkers of Postpartum Depression: A Narrative Review

Postpartum depression (PPD) is a disorder that impairs the formation of the relationship between mother and child, and reduces the quality of life for affected women to a functionally significant degree. Studying markers associated with PPD can help in early detection, prevention, or monitoring treatment. The purpose of this paper is to review biomarkers linked to PPD and to present selected theories on the pathogenesis of the disease based on data from biomarker studies. The complex etiology of the disorder reduces the specificity and sensitivity of markers, but they remain a valuable source of information to help clinicians. The biggest challenge of the future will be to translate high-tech methods for detecting markers associated with postpartum depression into more readily available and less costly ones. Population-based studies are needed to test the utility of potential PPD markers.

Tryptophan metabolism as bridge between gut microbiota and brain in chronic social defeat stress-induced depression mice

Backgrounds

Gut microbiota plays a critical role in the onset and development of depression, but the underlying molecular mechanisms are unclear. This study was conducted to explore the relationships between gut microbiota and host's metabolism in depression.

Methods

Chronic social defeat stress (CSDS) model of depression was established using C57BL/6 male mice. Fecal samples were collected from CSDS group and control group to measure gut microbiota and microbial metabolites. Meanwhile, tryptophan metabolism-related metabolites in hippocampus were also analyzed.

Results

CSDS successfully induced depressive-like behaviors in CSDS group. The 24 differential bacterial taxa between the two groups were identified, and 14 (60.87%) differential bacterial taxa belonged to phylum Firmicutes. Functional analysis showed that tryptophan metabolism was significantly affected in CSDS mice. Meanwhile, 120 differential microbial metabolites were identified, and two key tryptophan metabolism-related metabolites (tryptophan and 5-hydroxytryptophan (5-HTP)) were significantly decreased in feces of CSDS mice. The correlation analysis found the significant relationships between tryptophan and differential bacterial taxa under Firmicutes, especially genus Lactobacillus (r=0.801, p=0.0002). In addition, the significantly decreased 5-hydroxytryptamine (5-HT) in hippocampus of depressed mice was also observed.

Conclusions

Our results showed that tryptophan metabolism might have an important role in the crosstalk between gut microbioa and brain in depression, and phylum Firmicutes, especially genus Lactobacillus, might be involved in the onset of depression through regulating tryptophan metabolism.

Low-intensity focused ultrasound stimulation reverses social avoidance behavior in mice experiencing social defeat stress

The excitatory neurons of the medial prefrontal cortex (mPFC) respond to social stimuli. However, little is known about how the neural activity is altered during social avoidance, and whether it could act as a target of low-intensity focused ultrasound stimulation (LIFUS) to rescue social deficits. The present study aimed to investigate the mechanisms of neuronal activities and inflammatory responses underlying the effect of LIFUS on social avoidance. We found that chronic LIFUS stimulation can effectively improve social avoidance in the defeated mice. Calcium imaging recordings by fiber photometry in the defeated mice showed inhibited ensemble activity during social behaviors. LIFUS instantaneously triggered the mPFC neuronal activities, and chronic LIFUS significantly enhanced their neuronal excitation related to social interactions. We further found that the excessive activation of microglial cells and the overexpression of the inflammation signaling, i.e. Toll-like receptors(TLR4)/nuclear factor-kappaB(NF-КB), in mPFC were significantly inhibited by LIFUS. These results suggest that the LIFUS may inhibit social avoidance behavior by reducing activation of the inflammatory response, increasing neuronal excitation, and protecting the integrity of the neuronal structure in the mPFC. Our findings raised the possibility of LIFUS being applied as novel neuromodulation for social avoidance treatment in neuropsychiatric diseases.

Tanshinone IIA ameliorates chronic unpredictable mild stress-induced depression-like behavior and cognitive impairment in rats through the BDNF/TrkB/GAT1 signaling pathway

BACKGROUND

Depression is a common disorder with a complex pathogenesis. Tanshinone IIA (TAN IIA) is a botanical agent with neuroprotective and antidepressant properties.

OBJECTIVE

To examine the effects of TAN IIA on chronic unpredictable mild stress (CUMS)-induced depression-like behavior and cognitive impairment in rats.

METHODS

Rats were exposed to CUMS for 4 weeks, followed by the oral administration of TAN IIA, Deanxit (DEAN), or normal saline for an additional 4 weeks. The control rats were fed with regular chow and administered with normal saline for 4 weeks. Behavioral tests were performed to assess the effects of TAN IIA on depression-like behavior and cognitive impairment in rats with CUMS. The morphology of dendrites was analyzed by Golgi staining. Immunofluorescence staining was performed to determine protein localization.

RESULTS

TAN IIA treatment ameliorated CUMS-induced depression-like behavior and cognitive impairment in rats. TAN IIA treatment also reversed the effects of CUMS on dendritic complexity and the levels of gamma-aminobutyric acid (GABA) in the hippocampus and prefrontal cortex. Rats with CUMS showed decreased levels of brain-derived neurotrophic factor (BDNF) and phosphorylated tropomyosin receptor kinase B (TrkB), upregulated expression of GABA transporter 1 (GAT1), and reduced expression of synaptic proteins in the hippocampus, while TAN IIA treatment significantly diminished the effects of CUMS exposure. In addition, GAT1 was colocalized with N-methyl-D-aspartate receptor 2B.

CONCLUSION

TAN IIA ameliorates CUMS-induced depression-like behavior and cognitive impairment in rats by regulating the BDNF/TrkB/GAT1 signaling pathway, suggesting that TAN IIA may be a candidate drug for the treatment of depression.

Associations Between Disordered Microbial Metabolites and Changes of Neurotransmitters in Depressed Mice

Backgrounds

Many pieces of evidence demonstrated that there were close relationships between gut microbiota and depression. However, the specific molecular mechanisms were still unknown. Here, using targeted metabolomics, this study was conducted to explore the relationships between microbial metabolites in feces and neurotransmitters in prefrontal cortex of depressed mice.

Methods

Chronic unpredictable mild stress (CUMS) model of depression was built in this study. Targeted liquid chromatography-mass spectrometry analysis was used to detect the microbial metabolites in feces and neurotransmitters in prefrontal cortex of mice. Both univariate and multivariate statistical analyses were applied to identify the differential microbial metabolites and neurotransmitters and explore relationships between them.

Results

Ninety-eight differential microbial metabolites (mainly belonged to amino acids, fatty acids, and bile acids) and 11 differential neurotransmitters (belonged to tryptophan pathway, GABAergic pathway, and catecholaminergic pathway) were identified. Five affected amino acid-related metabolic pathways were found in depressed mice. The 19 differential microbial metabolites and 10 differential neurotransmitters were found to be significantly correlated with depressive-like behaviors. The two differential neurotransmitters (tyrosine and glutamate) and differential microbial metabolites belonged to amino acids had greater contributions to the overall correlations between microbial metabolites and neurotransmitters. In addition, the significantly decreased L-tyrosine as microbial metabolites and tyrosine as neurotransmitter had the significantly positive correlation (r = 0.681, p = 0.0009).

Conclusions

These results indicated that CUMS-induced disturbances of microbial metabolites (especially amino acids) might affect the levels of neurotransmitters in prefrontal cortex and then caused the onset of depression. Our findings could broaden the understanding of how gut microbiota was involved in the onset of depression.

Neurotransmitter and Related Metabolic Profiling in the Nucleus Accumbens of Chronic Unpredictable Mild Stress-Induced Anhedonia-Like Rats

Major depressive disorder (MDD) is a serious mental disorder that affects many people. The neurotransmitter deficiency hypothesis has been the crux of much research on the treatment of depression. Anhedonia, as a core symptom, was closely associated with altered levels of 5-hydroxytryptamine (5-HT), dopamine (DA), and diverse types of glutamate (Glu) receptors in the nucleus accumbens (NAc). However, there were no reports showing how Glu changed in the NAc, and there were other unreported molecules involved in modulating stress-induced anhedonia. Thus, we investigated changes in neurotransmitters and their related metabolites in GABAergic, serotonergic and catecholaminergic pathways in the NAc of a rat model of chronic unpredictable mild stress- (CUMS-) induced anhedonia-like behavior. Then, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed to detect target neurotransmitters and related metabolites in the NAc. Finally, the Western blot was used to assess the expression of key enzymes and receptors. Here, we found that the 5-HT level in anhedonia-susceptible (Sus) rats was increased while the Glu level decreased. DA did not show a significant change among CUMS rats. Correspondingly, we detected a reduction in monoamine oxidase-A (MAOA) and Glu receptor 1 levels in anhedonia-Sus rats while Glu receptor 2 (GluR2) and NMDA2B levels were increased in anhedonia-resilient (Res) rats. We also found that the levels of glutamine (Gln), kynurenic acid (Kya), histamine (HA), L-phenylalanine (L-Phe), and tyramine (Tyra) were changed after CUMS. These alterations in neurotransmitters may serve as a new insight into understanding the development of anhedonia-like behavior in depression.

Chronic stress induces platinum and Niraparib resistance in mouse models of ovarian cancer

Resistance to platinum and PARP inhibitors represents a major barrier to the long-term survival of ovarian cancer patients. We aim to explore the potential role of chronic stress in drug resistance in ovarian cancer. Leveraging four ovarian cancer with chronic stress (OCCS) mouse models, we explore the therapeutic efficacy of platinum, Niraparib, and Docetaxel treatment in vivo, and compare the efficacy of these anti-tumor drugs in vitro using cell viability assays. Comparing the transcriptional characteristics in RNA-Seq of OCCS mice with public databases, we analyze the molecular mechanism of chronic stress promoting drug resistance in ovarian cancer. We find that chronic stress is positively correlated with platinum-resistant recurrence in ovarian cancer patients. Chronic stress can induce platinum and Niraparib resistance of ovarian cancer, but it does not affect the therapeutic efficacy of Docetaxel treatment in vivo. And the platinum-resistant cell lines are not sensitive to these anti-tumor drugs, which is different from the result in vivo. Then, we identify several gene networks and their constituent genes that are most significantly associated with chronic stress and drug resistance in ovarian cancer, including the glycolysis pathway and DNA damage. This study develops Niraparib and platinum-resistant in vivo models, reflecting the ability of OCCS mice to reproduce different aspects of human ovarian cancer molecular mechanism, and provides a new theoretical basis for overcoming the double drug resistance of ovarian cancer.

Does urinary metabolite signature act as a biomarker of post-stroke depression?

BACKGROUND

It is difficult to conduct the precise diagnosis of post-stroke depression (PSD) in clinical practice due to the complex psychopathology of depressive disorder. Several studies showed that gas chromatography-mass spectrometry (GC-MS)-identified urinary metabolite biomarkers could significantly discriminate PSD from stroke survivors.

METHODS

A systematic review was performed for the keywords of "urinary metabolite" and "PSD" using Medline, Cochrane Library, Embase, Web of Science, PsycINFO, Wanfang, CNKI, CBM, and VIP database from inception to 31 March 2022.

RESULTS

Four related studies were included in the review. Differential urinary metabolites including lactic acid, palmitic acid, azelaic acid, and tyrosine were identified in all the included studies. As a significant deviation in the metabolite biomarker panel, glyceric acid, azelaic acid, phenylalanine, palmitic acid, pseudouridine, and tyrosine were found in at least 2 included studies, which indicated good potential for the differentiation of PSD.

CONCLUSION

The systematic review provided evidence that differential urinary metabolites analyzed by the GC-MS-based approach might be used as a biomarker for the diagnosis and prognosis of PSD.

Evaluation of the combined toxicity of multi-walled carbon nanotubes and cadmium on earthworms in soil using multi-level biomarkers

The coexistence of multi-walled carbon nanotubes (MWCNTs) with cadmium (Cd) in soil may cause the combined biological effects, but few study reported about their joint toxic effects on earthworms. Therefore, this study investigated the effects of sub-lethal levels of MWCNTs (10, 50, 100 mg/kg) and Cd (2.0, 10 mg/kg) on earthworms Eisenia fetida for 14 days. The changes in multi-level biomarkers of growth inhibition rate, cytochrome P450 isoenzymes (CYP1A2, 2C9 and 3A4), and small molecular metabolites (metabolomics) were determined. The toxic interaction between MWCNTs and Cd was characterized by the combination of the biomarker integration index (BRI), joint effect index concentration addition index (CAI), and the effect concentration addition index (EAI). The results showed that the single MWCNTs exposure caused insignificant change in most biomarkers, while the combined exposure of MWCNTs (50-100 mg/kg) and 10 mg/kg Cd led to significant changes in ten most important metabolites identified by metabolomics and activities of CYP1A2, 2C9, and 3A4. Compared with the toxicity of Cd alone, the combined toxicity of the mixture was significantly reduced. According to the integration of BRI and CAI/EAI, a clearly antagonistic interaction at relatively low effects was observed between MWCNTs and Cd. The responses of multiple biomarkers suggest the toxic action mode of the mixture on earthworms was related to the oxidative injury, and the disruption of amino acid, purine, and pyrimidine metabolism, and the urea cycle.

Altered Fecal Metabolites and Colonic Glycerophospholipids Were Associated With Abnormal Composition of Gut Microbiota in a Depression Model of Mice

The microbiota–gut–brain axis has been considered to play an important role in the development of depression, but the underlying mechanism remains unclear. The gastrointestinal tract is home to trillions of microbiota and the colon is considered an important site for the interaction between microbiota and host, but few studies have been conducted to evaluate the alterations in the colon. Accordingly, in this study, we established a chronic social defeated stress (CSDS) mice model of depression. We applied 16S rRNA gene sequencing to assess the gut microbial composition and gas and liquid chromatography–mass spectroscopy to identify fecal metabolites and colonic lipids, respectively. Meanwhile, we used Spearman’s correlation analysis method to evaluate the associations between the gut microbiota, fecal metabolites, colonic lipids, and behavioral index. In total, there were 20 bacterial taxa and 18 bacterial taxa significantly increased and decreased, respectively, in the CSDS mice. Further, microbial functional prediction demonstrated a disturbance of lipid, carbohydrate, and amino acid metabolism in the CSDS mice. We also found 20 differential fecal metabolites and 36 differential colonic lipids (in the category of glycerolipids, glycerophospholipids, and sphingolipids) in the CSDS mice. Moreover, correlation analysis showed that fecal metabolomic signature was associated with the alterations in the gut microbiota composition and colonic lipidomic profile. Of note, three lipids [PC(16:0/20:4), PG(22:6/22:6), and PI(18:0/20:3), all in the category of glycerophospholipids] were significantly associated with anxiety- and depression-like phenotypes in mice. Taken together, our results indicated that the gut microbiota might be involved in the pathogenesis of depression via influencing fecal metabolites and colonic glycerophospholipid metabolism.

Serum Metabolic Profiling of Late-Pregnant Women With Antenatal Depressive Symptoms

Background: Antenatal depression (AD) is a major public health issue worldwide and lacks objective laboratory-based tests to support its diagnosis. Recently, small metabolic molecules have been found to play a vital role in interpreting the pathogenesis of AD. Thus, non-target metabolomics was conducted in serum. Methods: Liquid chromatography-tandem mass spectrometry-based metabolomics platforms were used to conduct serum metabolic profiling of AD and non-antenatal depression (NAD). Orthogonal partial least squares discriminant analysis, the non-parametric Mann-Whitney U test, and Benjamini-Hochberg correction were used to identify the differential metabolites between AD and NAD groups; Spearman's correlation between the key differential metabolites and Edinburgh Postnatal Depression Scale (EPDS) and the stepwise logistic regression analysis was used to identify potential biomarkers. Results: In total, 79 significant differential metabolites between AD and NAD were identified. These metabolites mainly influence amino acid metabolism and glycerophospholipid metabolism. Then, PC (16:0/16:0) and betaine were significantly positively correlated with EPDS. The simplified biomarker panel consisting of these three metabolites [betaine, PC (16:0/16:0) and succinic acid] has excellent diagnostic performance (95% confidence interval = 0.911-1.000, specificity = 95%, sensitivity = 85%) in discriminating AD and NAD. Conclusion: The results suggested that betaine, PC (16:0/16:0), and succinic acid were potential biomarker panels, which significantly correlated with depression; and it could make for developing an objective method in future to diagnose AD.

Proteomic and metabolomic characterization of amygdala in chronic social defeat stress rats

BACKGROUND

Depression is a leading cause of disability worldwide. There is increasing evidence showing that depression is associated with the pathophysiology in amygdala; however, the underlying mechanism remains poorly understood.

METHOD

We established a rat model of chronic social defeat stress (CSDS) and conducted a series of behavior tests to observe behavioral changes. Then liquid chromatography mass spectrometry (LC-MS)-based metabolomics and isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomics were employed to detect metabolomes and proteomes in the amygdala, respectively. Ingenuity pathway analysis (IPA) and other bioinformatic analyses were used to analyze differentially expressed metabolites and proteins.

RESULTS

The significantly lower sucrose preference index in the sucrose preference test and longer immobile time in the forced swim test were observed in the CSDS rats compared with control rats. In the multi-omics analysis, thirty-seven significantly differentially expressed metabolites and 123 significant proteins were identified. Integrated analysis of differentially expressed metabolites and proteins by IPA revealed molecular changes mainly associated with synaptic plasticity, phospholipase c signaling, and glutamine degradation I. We compared the metabolites in the amygdala with those in the hippocampus and prefrontal cortex from our previous studies and found two common metabolites: arachidonic acid and N-acetyl-l-aspartic acid among these three brain regions.

CONCLUSION

Our study revealed the presence of depressive-like behaviors and molecular changes of amygdala in the CSDS rat model, which may provide further insights into the pathogenesis of depression, and help to identify potential targets for antidepressants.

Assessment of Phytochemicals and Herbal Formula for the Treatment of Depression through Metabolomics

Depression is a widespread and persistent psychiatric disease. Due to various side effects and no curative treatments of conventional antidepressant drugs, botanical medicines have attracted considerable attention as a complementary and alternative approach. The pathogenesis of depression is quite complicated and unclear. Metabolomics is a promising new technique for the discovery of novel biomarkers for exploring the potential mechanisms of diverse diseases and assessing the therapeutic effects of drugs. In this article, we systematically reviewed the study of botanical medicine for the treatment of depression using metabolomics over a period from 2010 to 2019. Additionally, we summarized the potential biomarkers and metabolic pathways associated with herbal medicine treatment for depression. Through a comprehensive evaluation of herbal medicine as novel antidepressants and understanding of their pharmacomechanisms, a new perspective on expanding the application of botanical medicines for the treatment of depression is provided.

Prolonged chronic social defeat stress promotes less resilience and higher uniformity in depression-like behaviors in adult male mice

Chronic social defeat stress (CSDS) is widely applied to study of depression in rodents. 10-day CSDS was a most commonly employed paradigm but with high resilience ratio (∼30%), producing potential variation in depression-like behavioral symptoms. Whether prolonged period (21 days) of CSDS would promote less resilience and reduce behavioral variability remains unknown. We applied 10-day and 21-day CSDS paradigms to induce mouse model of depression and compared their resilience ratio and behavioral phenotypes. Mice under 21-day CSDS had significantly lower resilience ratio and greater changes in behavioral indicators relative to mice under 10-day CSDS. Behavioral indicators from 21-day CSDS paradigm had higher correlations and better prediction for susceptibility which indicating higher uniformity in behavioral phenotypes. Furthermore, a subset of behavioral indicators in 21-day CSDS had high prediction efficacy and should be first applied to screen susceptibility of CSDS. Thus, our study demonstrates that 21-day CSDS is a more robust paradigm inducing reliable depression-like behaviors relative to 10-day CSDS, and should be preferentially used in rodent studies of depression.

Perturbations in Amino Acid Metabolism in Reserpine-Treated Zebrafish Brain Detected by 1H Nuclear Magnetic Resonance-Based Metabolomics

Depression is a complex and disabling psychiatric disorder, which is expected to be a leading cause for disability by 2030. According to World Health Organization, about 350 million people are suffering with mental health disorders around the globe, especially depression. However, the mechanisms involved in stress-induced depression have not been fully elucidated. In this study, a stress-like state was pharmacologically induced in zebrafish using reserpine, a drug widely used to mediate depression in experimental animal models. Zebrafish received single intraperitoneal (i.p.) injections of 20, 40, and 80 mg/kg body weight reserpine doses and were subjected to open-field test at 2, 24, 48, 72, and 96 h after the treatment. Along with observed changes in behavior and measurement of cortisol levels, the fish were further examined for perturbations in their brain metabolites by ¹H nuclear magnetic resonance (NMR)-based metabolomics. We found a significant increase in freezing duration, whereas total distance travelled was decreased 24 h after single intraperitoneal injection of reserpine. Cortisol level was also found to be higher after 48 h of reserpine treatment. The ¹H NMR data showed that the levels of metabolites such as glutamate, glutamine, histamine, valine, leucine and histidine, lactate, l-fucose, betaine and γ-amino butyric acid (GABA), β-hydroxyisovalerate, and glutathione were significantly decreased in the reserpine-treated group. This study provided some insights into the molecular nature of stress that could contribute toward a better understanding of depression disorder.

CD36 deficiency affects depressive-like behaviors possibly by modifying gut microbiota and the inflammasome pathway in mice

Both inflammatory processes and gut microbiota have been implicated in the pathophysiology of depressive disorders. The class B scavenger receptor CD36 is involved in the cytotoxicity associated with inflammation. However, its role in depression has not yet been examined. In this study, we investigated whether CD36 affects depression by modulating the microbiota-gut-inflammasome-brain axis. We used CD36^-/- (knockout) mice subjected to chronic social defeat stress, and measured the expression of CD36 in these depressed mice and in patients with depression. The hippocampus of CD36^-/- mice was used to investigate changes in the NLRP3 inflammasome signaling pathway. The 16S rRNA gene sequence-based approach was used to compare the cecal microbial communities in CD36^-/- and WT mice. The CD36 deficiency in CD36^-/- mice alleviated chronic stress-induced depression-like behaviors. CD36 was upregulated in depressed mice as well as in depressed patients. Furthermore, the NLRP3 inflammasome signaling pathway was downregulated in the hippocampus of CD36^-/- mice. The Simpson Diversity Index revealed increased cecal bacterial alpha-diversity in the CD36^-/- mice. Among genera, Bacteroides, Rikenella, and Alloprevotella were significantly more abundant in the CD36^-/- mice, whereas Allobaculum was less abundant, consistent with the attenuated inflammation in the hippocampus of CD36^-/- mice. Our findings suggest that CD36 deficiency changes the gut microbiota composition, which in turn may impact depressive-like behaviors by affecting the inflammasome pathway.

Mechanism of Intermittent Theta-Burst Stimulation in Synaptic Pathology in the Prefrontal Cortex in an Antidepressant-Resistant Depression Rat Model

Intermittent theta-burst stimulation (iTBS), a form of repetitive transcranial magnetic stimulation, is considered a potential therapy for treatment-resistant depression. The synaptic mechanism of iTBS has long been known to be an effective method to induce long-term potentiation (LTP)-like plasticity in humans. However, there is limited evidence as to whether the antidepressant effect of iTBS is associated with change in synaptic function in the prefrontal cortex (PFC) in preclinical study. Hence, we applied an antidepressant (i.e., fluoxetine)-resistant depression rat model induced by severe foot-shocks to investigate the antidepressant efficacy of iTBS in the synaptic pathology. The results showed that iTBS treatment improved not only the impaired LTP, but also the aberrant long-term depression in the PFC of antidepressant-resistant depression model rats. Moreover, the mechanism of LTP improvement by iTBS involved downstream molecules of brain-derived neurotrophic factor, while the mechanism of long-term depression improvement by iTBS involved downstream molecules of proBDNF. The aberrant spine morphology was also improved by iTBS treatment. This study demonstrated that the mechanism of the iTBS paradigm is complex and may regulate not only excitatory but also inhibitory synaptic effects in the PFC.

Natural volatile oils derived from herbal medicines: A promising therapy way for treating depressive disorder

Depression is a common global mental disorder that seriously harms human physical and mental health. With the development of society, the increase of pressure and the role of various other factors make the incidence of depression increase year by year. However, there is a lack of drugs that have a fast onset, significant effects, and few side effects. Some volatile oils from traditional natural herbal medicines are usually used to relieve depression and calm emotions, such as Lavender essential oil and Acorus tatarinowii essential oil. It was reported that these volatile oils, are easy to enter the brain through the blood-brain barrier and have good antidepressant effects with little toxicity and side effects. In this review, we summarized the classification of depression, and listed the history of using volatile oils to fight depression in some countries. Importantly, we summarized the anti-depressant natural volatile oils and their monomers from herbal medicine, discussed the anti-depressive mechanisms of the volatile oils from natural medicine. The volatile oils of natural medicine and antidepressant drugs were compared and analyzed, and the application of volatile oils was explained from the clinical use and administration routes. This review would be helpful for the development of potential anti-depressant medicine and provide new alternative treatments for depressive disorders.

Xanthotoxin affects depression-related behavior and neurotransmitters content in a sex-dependent manner in mice

The present study aimed to evaluate xanthotoxin's influence on male and female Swiss mice's depression-like behaviors and investigate the potential mechanism of this effect. Naturally derived furanocoumarin (the Apiaceae family), xanthotoxin, administered acutely (12.5 mg/kg), diminished the immobility level in the forced swim test only in males. The immobility level was lower in females than males, which may be associated with a higher serotonin level in the female prefrontal cortex. A dose-dependent increase of serotonin and noradrenaline was reported in the reverse-phase ion-pair liquid chromatography in the female prefrontal cortex but not in the hippocampus. We suggest that xanthotoxin may exert antidepressant properties and affect males and females differently. The increasing level of serotonin in the male and female prefrontal cortex may underlie this effect.

iTRAQ-based proteomics implies inflammasome pathway activation in the prefrontal cortex of CSDS mice may influence resilience and susceptibility

AIMS

Major depressive disorder, as a destructive mental health disorder, is a major contributor to disability and death. Numerous studies have illustrated that activation of inflammation and fluctuating immune reactions play a crucial role in the physiopathology of depression. The effectiveness of antidepressants is affected by the intensity of the inflammatory response. Thus, we aim to reveal the correlation of inflammatory factors and depression.

MAIN METHODS

Isobaric tags for relative and absolute quantitation (iTRAQ™)-based proteomics was applied to verify the quantitation of target proteins in the PFC of chronic social defeat stress (CSDS) model mice. Ingenuity pathway analysis (IPA) was performed to explore related pathways, and the involvement of molecules was validated by western blotting and real time-quantitative polymerase chain reaction (RT-qPCR).

KEY FINDINGS

According to the IPA results, CSDS-susceptible mice and CSDS-resilient mice both exhibited alterations of the inflammasome pathway in the PFC. Compared with control mice, susceptible mice subjected to CSDS showed an increased ATP-activated purinergic receptor P2X7 (also known as P2RX7) protein level. Nevertheless, the expression levels of cysteinyl aspartate-specific protease 1 (Caspase 1) and apoptosis-associated speck-like protein containing a CARD (ASC) were reduced in CSDS mice, and downregulation of interleukin-1β (IL-1β) was found in susceptible mice. Moreover, no significant difference was found in nuclear factor-κB levels among the three groups.

SIGNIFICANCE

CSDS administration leads to dysfunctions of key molecules in the inflammasome pathway, promoting depressive-like behaviors in mice.

Metabolomic analysis of animal models of depression

BACKGROUND

Our understanding of the molecular mechanisms of depression remains largely unclear. Previous studies have shown that the prefrontal cortex (PFC) is among most important brain regions that exhibits metabolic changes in depression. A comprehensive analysis based on candidate metabolites in the PFC of animal models of depression will provide valuable information for understanding the pathogenic mechanism underlying depression.

METHODS

Candidate metabolites that are potentially involved in the metabolic changes of the PFC in animal models of depression were retrieved from the Metabolite Network of Depression Database. The significantly altered metabolic pathways were revealed by canonical pathway analysis, and the relationships among altered pathways were explored by pathway crosstalk analysis. Additionally, drug-associated pathways were investigated using drug-associated metabolite set enrichment analysis. The interrelationships among metabolites, proteins, and other molecules were analyzed by molecular network analysis.

RESULTS

Among 88 candidate metabolites, 87 altered canonical pathways were identified, and the top five ranked pathways were tRNA charging, the endocannabinoid neuronal synapse pathway, (S)-reticuline biosynthesis II, catecholamine biosynthesis, and GABA receptor signaling. Pathway crosstalk analysis revealed that these altered pathways were grouped into three interlinked modules involved in amino acid metabolism, nervous system signaling/neurotransmitters, and nucleotide metabolism. In the drug-associated metabolite set enrichment analysis, the main enriched drug pathways were opioid-related and antibiotic-related action pathways. Furthermore, the most significantly altered molecular network was involved in amino acid metabolism, molecular transport, and small molecule biochemistry.

CONCLUSIONS

This study provides important clues for the metabolic characteristics of the PFC in depression.

Nedd4l downregulation of NRG1 in the mPFC induces depression-like behaviour in CSDS mice

The occurrence of major depressive disorders has been closely related to the vulnerability of stress. The medial prefrontal cortex (mPFC) is involved in regulating pathological reactivity to stress, changes in affective behaviour and cognitive functions by distress. Increasing evidence indicates that neuregulin 1 (NRG1) plays an important role in psychiatric illnesses, including depression, schizophrenia and bipolar disorder. However, whether NRG1 in the mPFC is related to stress vulnerability remains unclear. We here assessed the regulation of NRG1 by the E3 ubiquitin ligase Nedd4l (neural precursor cell expressed developmentally downregulated 4-like) and investigated whether NRG1 changes in the mPFC might lead to vulnerability to depression-like behaviours. We've identified a deficiency of NRG1 in the mPFC as a key factor that contributes to the regulation of stress susceptibility in mice, as further suggested by the finding that overexpression of NRG1 attenuated depression-like behaviours in the animal model of chronic social defeat stress (CSDS). Interestingly, RNA sequencing in the mPFC brain region showed no differences in NRG1 mRNA levels between control animals and stress-susceptible (SS) or resilient mice (RES) following CSDS. However, mRNA and protein levels of Nedd4l were markedly increased in SS mice, but not in RES mice compared to controls. Furthermore, ubiquitination of NRG1 was increased in SS mice. Remarkably, overexpression of Nedd4l in mouse mPFC induced a decrease in NRG1 level and caused vulnerability to stress by subthreshold social defeat stress (SSDS), while downregulation of Nedd4l expression in the mPFC rescued the vulnerability to stress-induced social avoidance and anhedonia. Our data strongly indicate that the Nedd4l-mediated downregulation of NRG1 acts as a critical role in depression-like phenotypes of mice in CSDS.

Major depression accompanied with inflammation and multiple cytokines alterations: Evidences from clinical patients to macaca fascicularis and LPS-induced depressive mice model

BACKGROUND

Inflammation progress has been consistently implicated in the pathophysiology of major depressive disorder (MDD). However, the underlying mechanism of inflammation and depressive symptoms still far from being fully elucidated. In addition, studies on emotional disorders could also benefit from model of the non-human primates. To explore the difference of serum multi-cytokines levels among the MDD patients and depressed macaca fascicularis as well as LPS-treated mice, thus may find the reliable potential biomarkers for MDD.

METHODS

Serum multi-cytokines levels among MDD patients (n = 44) and depressed macaca fascicularis (n = 6) together with controls (n = 22 for human, n = 6 for macaques) were detected by the Bio-Plex cytokines panel. Then five of these serum cytokines in LPS-treated mice were measured via ELISA. Furthermore, these cytokines protein expressions were validated by western blotting in three depression-related regions of LPS-treated mice.

RESULTS

Here, we found that MDD patients displayed increased concentration of 13 proinflammatory and anti-inflammatory cytokines accompanied with one decreased cytokine in peripheral serum. Meanwhile, the naturally occurring depression (NOD) macaca fascicularis merely exhibited elevated concentration of 4 peripheral cytokines (IL-6, IL-8, MCP-1, VEGF), which were in accordance with the outcomes of MDD patients. Importantly, the serum and brain tissues of LPS-treated mice also emerged similar cytokines alterations.

CONCLUSION

In summary, our findings strengthen the evidence that cytokines were associated with the depression, and the IL-6 and VEGF may as predictive biomarkers for novel diagnostic as well as therapeutic of depression. The hypothalamus may as a key brain region involve in the inflammatory related depressive-like behaviors.

Metabolomic abnormalities of purine and lipids implicated olfactory bulb dysfunction of CUMS depressive rats

Major depressive disorder (MDD) is a serious mood disorder and leads to a high suicide rate as well as financial burden. The volume and function (the sensitivity and neurogenesis) of the olfactory bulb (OB) were reported to be altered among the MDD patients and rodent models of depression. In addition, the olfactory epithelium was newly reported to decrease its volume and function under chronic unpredictable mild stress (CUMS) treatment. However, the underlying molecular mechanism still remains unclear. Herein, we conducted the non-targeted metabolomics method based on gas chromatography-mass spectrometry (GC-MS) coupled with multivariate statistical analysis to characterize the differential metabolites in OB of CUMS rats. Our results showed that 19 metabolites were categorized into two perturbed pathways: purine metabolism and lipid metabolism, which were regarded as the vital pathways concerned with dysfunction of OB. These findings indicated that the turbulence of metabolic pathways may be partly responsible for the dysfunction of OB in MDD.

Diterpene Ginkgolides Exert an Antidepressant Effect Through the NT3-TrkA and Ras-MAPK Pathways

Background

Depression is a highly prevalent mental illness that severely impacts the quality of life of affected individuals. Our recent studies demonstrated that diterpene ginkgolides (DG) have antidepressant effects in mice. However, the underlying molecular mechanisms remained much unclear.

Methods

In this study, we assessed the antidepressant effects of chronic DG therapy in rats by evaluating depression-related behaviors, we also examined potential side effects using biochemical indicators. Furthermore, we performed an in-depth molecular network analysis of gene–protein–metabolite interactions on the basis of metabolomics.

Results

Chronic DG treatment significantly ameliorated the depressive-like behavioral phenotype. Furthermore, the neurotrophin signaling-related NT3-TrkA and Ras-MAPK pathways may play an important role in the antidepressant effect of DG in the hippocampus.

Conclusion

These findings provide novel insight into the mechanisms underlying the antidepressant action of DG, and should help advance the development of new therapeutic strategies for depression.

Pigment epithelium-derived factor alleviates depressive-like behaviors in mice by modulating adult hippocampal synaptic growth and Wnt pathway

Pigment epithelium-derived factor (PEDF, also known as SERPINF1) is a secreted glycoprotein with neuroprotective effects. However, the potential role of PEDF in major depressive disorder (MDD) remains largely unknown. Here, applying two-dimensional gel electrophoresis (2-DE) proteomics, we found that PEDF levels were significantly decreased in the plasma of 12 first-episode treatment-naïve MDD patients (FETND) compared to the levels in 12 healthy controls (HCs). PEDF levels were especially lower in MDD patients than in HCs and patients with bipolar disorder (BD) and schizophrenia (SCZ), and elevated PEDF were consistent with decreased HAM-D scores in patients given antidepressant therapy (ADT). Animal research indicated that PEDF was decreased in the periphery and hippocampus of two well-known depression rodent models (the chronic unpredictable mild stress (CUMS) rat model and chronic social defeat stress (CSDS) mouse model). Decreased PEDF levels in the hippocampus led to depressive-like behaviors, synaptic impairments and aberrant Wnt signaling in C57BL mice, while increased PEDF resulted in the opposite results. Mechanistic studies indicated that PEDF contributes to dendritic growth and Wnt signaling activation in the hippocampus of adult mice. Taken together, the results of our study demonstrate the involvement of PEDF and its related mechanism in depression, thus providing translational evidence suggesting that PEDF may be a novel therapeutic target for depression.

Metabolomics in Psychiatric Disorders: What We Learn from Animal Models

Biomarkers are a recent research target within biological factors of psychiatric disorders. There is growing evidence for deriving biomarkers within psychiatric disorders in serum or urine samples in humans, however, few studies have investigated this differentiation in brain or cerebral fluid samples in psychiatric disorders. As brain samples from humans are only available at autopsy, animal models are commonly applied to determine the pathogenesis of psychiatric diseases and to test treatment strategies. The aim of this review is to summarize studies on biomarkers in animal models for psychiatric disorders. For depression, anxiety and addiction disorders studies, biomarkers in animal brains are available. Furthermore, several studies have investigated psychiatric medication, e.g., antipsychotics, antidepressants, or mood stabilizers, in animals. The most notable changes in biomarkers in depressed animal models were related to the glutamate-γ-aminobutyric acid-glutamine-cycle. In anxiety models, alterations in amino acid and energy metabolism (i.e., mitochondrial regulation) were observed. Addicted animals showed several biomarkers according to the induced drugs. In summary, animal models provide some direct insights into the cellular metabolites that are produced during psychiatric processes. In addition, the influence on biomarkers due to short- or long-term medication is a noticeable finding. Further studies should combine representative animal models and human studies on cerebral fluid to improve insight into mental disorders and advance the development of novel treatment strategies.

Entorhinal cortex-based metabolic profiling of chronic restraint stress mice model of depression

Despite that millions of people suffer from major depressive disorder (MDD), the mechanism underlying MDD remains elusive. Recently, it has been reported that entorhinal cortex (EC) functions on the regulation of depressive-like phenotype relying on the stimulation of glutamatergic afferent from EC to hippocampus. Based on this, we used liquid chromatography-tandem mass spectrometry method to explore metabolic alterations in the EC of mice after exposed to chronic restraint stress (CRS). Molecular validation was conducted via the application of western blot and RT-qPCR. Through this study, we found significant upregulation of glutamate, ornithine aspartic acid, 5-hydroxytryptophan, L-tyrosine and norepinephrine in CRS group, accompanied with downregulation of homovanillic acid. Focusing on these altered metabolic pathways in EC, we found that gene levels of GAD1, GLUL and SNAT1 were increased. Upregulation of SERT and EAAT2 in protein expression level were also validated, while no significant changes were found in TH, AADC, MAOA, VMAT2, GAD1, GLUL and SNAT1. Our findings firstly provide evidence about the alteration of metabolites and related molecules in the EC of mice model of depression, implying the potential mechanism in MDD pathology.

Dl-3-n-butylphthalide attenuates mouse behavioral deficits to chronic social defeat stress by regulating energy metabolism via AKT/CREB signaling pathway

Major depressive disorder (MDD) is a severe mental disorder associated with high rates of morbidity and mortality. Current first-line pharmacotherapies for MDD are based on enhancement of monoaminergic neurotransmission, but these antidepressants are still insufficient and produce significant side-effects. Consequently, the development of novel antidepressants and therapeutic targets is desired. Dl-3-n-butylphthalide (NBP) is a compound with proven efficacy in treating ischemic stroke, yet its therapeutic effects and mechanisms for depression remain unexplored. The aim of this study was to investigate the effect of NBP in a chronic social defeat stress model of depression and its underlying molecular mechanisms. Here, we examined depression-related behavior and performed a targeted metabolomics analysis. Real-time quantitative polymerase chain reaction and western blotting were used to examine key genes and proteins involved in energy metabolism and the AKT/cAMP response element-binding protein (CREB) signaling pathway. Our results reveal NBP attenuates stress-induced social deficits, anxiety-like behavior and despair behavior, and alters metabolite levels of glycolysis and tricarboxylic acid (TCA) cycle components. NBP affected gene expression of key enzymes of the TCA cycle, as well as protein expression of p-AKT and p-CREB. Our findings provide the first evidence showing that NBP can attenuate stress-induced behavioral deficits by modulating energy metabolism by regulating activation of the AKT/CREB signaling pathway.

Chronic Stress in a Rat Model of Depression Disturbs the Glutamine-Glutamate-GABA Cycle in the Striatum, Hippocampus, and Cerebellum

BACKGROUND

Major depressive disorder (MDD) is a complex psychiatric illness involving multiple brain regions. Increasing evidence indicates that the striatum is involved in depression, but the molecular mechanisms remain unclear.

METHODS

In this study, we performed a gas chromatography-mass spectrometer (GC/MS)-based metabolomic analysis in the striatum of depressed rats induced by chronic unpredictable mild stress (CUMS). We then compared striatal data with our previous data from the hippocampus and cerebellum to systematically investigate the potential pathogenesis of depression.

RESULTS

We identified 22 differential metabolites in the striatum between the CUMS and control groups; these altered metabolites were mainly involved in amino acid, carbohydrate, and nucleotide metabolism. Pathway analysis revealed that the shared metabolic pathways of the striatum, hippocampus, and cerebellum were mainly involved in the glutamine-glutamate metabolic system. Four genes in the striatum (GS, GLS2, GLT1, and SSADH), six genes in the hippocampus (GS, SNAT1, GAD1, SSADH, VGAT, and ABAT), and five genes in the cerebellum (GS, ABAT, SNAT1, VGAT, and GDH) were found to be significantly altered using RT-qPCR. Correlation analysis indicated that these differential genes were strongly correlated.

CONCLUSION

These results suggest that chronic stress might induce depressive behaviors by disturbing the glutamine-glutamate-GABA cycle in the striatum, hippocampus, and cerebellum, and that the glutamine-glutamate-GABA cycle among these three brain regions might generate cooperative action in response to chronic stress.

Perturbation of Ephrin Receptor Signaling and Glutamatergic Transmission in the Hypothalamus in Depression Using Proteomics Integrated With Metabolomics

Hypothalamic dysfunction is a key pathological factor in inflammation-associated depression. In the present study, isobaric tags for relative-absolute quantitation (iTRAQ) combined with mass spectrometry and gas chromatography-mass spectrometry (GC-MS) were employed to detect the proteomes and metabolomes in the hypothalamus of the lipopolysaccharide (LPS)-induced depression mouse, respectively. A total of 187 proteins and 27 metabolites were differentially expressed compared with the control group. Following the integration of bi-omics data, pertinent pathways and molecular interaction networks were further identified. The results indicated altered molecules were clustered into Ephrin receptor signaling, glutamatergic transmission, and inflammation-related signaling included the LXR/RXR activation, FXR/RXR activation, and acute phase response signaling. First discovered in the hypothalamus, Ephrin receptor signaling regulates N-methyl-D-aspartate receptor (NMDAR)-predominant glutamatergic transmission, and further acted on AKT signaling that contributed to changes in hypothalamic neuroplasticity. Ephrin type-B receptor 2 (EPHB2), a transmembrane receptor protein in Ephrin receptor signaling, was significantly elevated and interacted with the accumulated NMDAR subunit GluN2A in the hypothalamus. Additionally, molecules involved in synaptic plasticity regulation, such as hypothalamic postsynaptic density protein-95 (PSD-95), p-AKT and brain-derived neurotrophic factor (BDNF), were significantly altered in the LPS-induced depressed group. It might be an underlying pathogenesis that the EPHB2-GluN2A-AKT cascade regulates synaptic plasticity in depression. EPHB2 can be a potential therapeutic target in the correction of glutamatergic transmission dysfunction. In summary, our findings point to the previously undiscovered molecular underpinnings of the pathophysiology in the hypothalamus of inflammation-associated depression and offer potential targets to develop antidepressants.

Proteomic analysis of the intestine reveals SNARE-mediated immunoregulatory and amino acid absorption perturbations in a rat model of depression

AIMS

To clarify the role of the gut-brain axis in depression.

MAIN METHODS

We used the iTRAQ technique to identify differential proteins in the intestine of the rat model of chronic unpredictable mild stress (CUMS)-induced depression. Significant differential proteins were subjected to Gene Ontology (GO) functional annotations and KEGG pathway enrichment analysis. Key proteins were validated at the mRNA and protein levels. The levels of cytokines in the intestine, serum and hypothalamus were examined by ELISA. HPLC-UV was used to detect the levels of amino acids.

KEY FINDINGS

In the rat intestine, 349 differential proteins (209 downregulated, 140 upregulated) were identified. GO analysis indicated that "protein complex assembly" was the first-ranked biological process. SNARE complex components, including SNAP23, VAMP3 and VAMP8, were increased at the mRNA levels, while only VAMP3 and VAMP8 were also upregulated at the protein level. TNFα, IL6 and IL1β were upregulated in the CUMS rat intestine, while TNFα was decreased in the serum and hypothalamus. IL1β was decreased in the serum. "Protein digestion and absorption" was the most significantly enriched KEGG pathway, involving 5 differential proteins: SLC9A3, ANPEP, LAT1, ASCT2 and B⁰AT1. Glutamine, glycine and aspartic acid were perturbed in the CUMS rat intestine.

SIGNIFICANCE

Our findings suggest that CUMS enhances the adaptive immune response in the intestine through ER-phagosome pathway mediated by SNARE complex and disturb absorption of amino acids. It advances our understanding of the role of gut-brain axis in depression and provides a potential therapeutic target for the disease.

Development of an underivatized LC-MS/MS method for quantitation of 14 neurotransmitters in rat hippocampus, plasma and urine: Application to CUMS induced depression rats

Sensitive and comprehensive measurement of systemic metabolites of tryptophan, phenylalanine and glutamate metabolism in biological samples is effective for understanding the pathogenesis of depression and other neurological diseases. Therefore, this study developed an underivatized liquid chromatography tandem mass spectrometry (LC-MS/MS) method for simultaneous monitoring the 3 components of glutamate metabolism in rat hippocampus and 11 components of tryptophan and phenylalanine metabolism in rat hippocampus, plasma and urine, and applied it to investigate their changes in rats induced by chronic unpredictable mild stress (CUMS). The investigated analytes are as follows: tryptophan, serotonin, 5-hydroxyindoleacetic acid, kynurenine, kynurenic acid, xanthurenic acid, 3-hydroxyanthranilic acid, quinolinic acid, phenylalanine, tyrosine, tyramine, glutamate, glutamine and gamma-aminobutyric acid. The method was verified to be sensitive and effective with satisfactory linearity, accuracies in the range of 78.2%-120.4%, and precisions less than 17.8% for all identified analytes. A series of significant changes in CUMS-induced rats can be detected: tryptophan, serotonin and tyrosine levels decreased and quinolinic acid increased in both hippocampus and plasma. In addition, the kynurenine/tryptophan ratios increased in hippocampus and plasma, the kynurenic acid/quinolinic acid ratios of plasma and urine were significantly reduced. These findings demonstrated that the CUMS procedure could lead to the central and peripheral imbalances of tryptophan and phenylalanine metabolism. In conclusion, a LC-MS/MS method for simultaneous measurement of several neurotransmitters in rat hippocampus, plasma and urine was developed and successfully applied to investigation of the central and peripheral changes in CUMS-induced rats. The method would be expected to provide applicability to the study of the mechanisms of depression and other related diseases associated with these neurotransmitters.

A Preliminary Study of Uric Metabolomic Alteration for Postpartum Depression Based on Liquid Chromatography Coupled to Quadrupole Time-of-Flight Mass Spectrometry

Postpartum depression affects about 10-20% of newly delivered women, which is harmful for both mothers and infants. However, the current diagnosis of postpartum depression depends on the subjective judgment of a practitioner, which may lead to misdiagnosis. Hence, an appended objective diagnosis index may help the practitioner to improve diagnosis. A metabolomic study can find biomarkers as an objective index to facilitate disease diagnosis. Forty-nine postpartum depressed patients and 50 healthy controls were recruited into this study. The metabolites in urine were scanned with LC-Q-TOF-MS. The metabolomic data were analyzed with a multivariate statistical analysis method. Data from 40 patients and 40 controls were used for partial least square-discriminate analysis (PLS-DA). The urine metabolomic profiles of patients were different from those of controls. The PLS-DA model was validated by a permutation test, and the model could accurately classify the other 9 patients and 10 controls in T-prediction. Ten differentiating metabolites were found as main contributors to this difference, which are involved in amino acid metabolism, neurotransmitter metabolism, bacteria population, etc. Some of these potential biomarkers, such as 4-hydroxyhippuric acid, homocysteine, and tyrosine, showed relatively high sensitivities and specificities. The metabolic profile alteration induced by postpartum depression was found, and some of the differentiating metabolites may serve as biomarkers to facilitate the diagnosis of postpartum depression.

Absence of gut microbiota during early life affects anxiolytic Behaviors and monoamine neurotransmitters system in the hippocampal of mice

The gut microbiome is composed of an enormous number of microorganisms, generally regarded as commensal bacteria. Resident gut bacteria are an important contributor to health and significant evidence suggests that the presence of healthy and diverse gut microbiota is important for normal cognitive and emotional processing. Here we measured the expression of monoamine neurotransmitter-related genes in the hippocampus of germ-free (GF) mice and specific-pathogen-free (SPF) mice to explore the effect of gut microbiota on hippocampal monoamine functioning. In total, 19 differential expressed genes (Htr7, Htr1f, Htr3b, Drd3, Ddc, Maob, Tdo2, Fos, Creb1, Akt1, Gsk3a, Pik3ca, Pla2g5, Cyp2d22, Grk6, Ephb1, Slc18a1, Nr4a1, Gdnf) that could discriminate between the two groups were identified. Interestingly, GF mice displayed anxiolytic-like behavior compared to SPF mice, which were not reversed by colonization with gut microbiota from SPF mice. Besides, colonization of adolescent GF mice by gut microbiota was not sufficient to reverse the altered gene expression associated with their GF status. Taking these findings together, the absence of commensal microbiota during early life markedly affects hippocampal monoamine gene-regulation, which was associated with anxiolytic behaviors and monoamine neurological signs.

Integrated Metabolomics and Proteomics Analysis Revealed Second Messenger System Disturbance in Hippocampus of Chronic Social Defeat Stress Rat

Depression is a common and disabling mental disorder characterized by high disability and mortality, but its physiopathology remains unclear. In this study, we combined a non-targeted gas chromatography-mass spectrometry (GC-MS)-based metabolomic approach and isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic analysis to elucidate metabolite and protein alterations in the hippocampus of rat after chronic social defeat stress (CSDS), an extensively used animal model of depression. Ingenuity pathway analysis (IPA) was conducted to integrate underlying relationships among differentially expressed metabolites and proteins. Twenty-five significantly different expressed metabolites and 234 differentially expressed proteins were identified between CSDS and control groups. IPA canonical pathways and network analyses revealed that intracellular second messenger/signal transduction cascades were most significantly altered in the hippocampus of CSDS rats, including cyclic adenosine monophosphate (cAMP), phosphoinositol, tyrosine kinase, and arachidonic acid systems. These results provide a better understanding of biological mechanisms underlying depression, and may help identify potential targets for novel antidepressants.

Metabonomics reveals peripheral and central short-chain fatty acid and amino acid dysfunction in a naturally occurring depressive model of macaques

PURPOSE

Depression is a complex psychiatric disorder. Various depressive rodent models are usually constructed based on different pathogenesis hypotheses.

MATERIALS AND METHODS

Herein, using our previously established naturally occurring depressive (NOD) model in a non-human primate (cynomolgus monkey, Macaca fascularis), we performed metabolomics analysis of cerebrospinal fluid (CSF) from NOD female macaques (N=10) and age-and gender-matched healthy controls (HCs) (N=12). Multivariate statistical analysis was used to identify the differentially expressed metabolites between the two groups. Ingenuity Pathways Analysis and MetaboAnalyst were applied for predicted pathways and biological functions analysis.

RESULTS

Totally, 37 metabolites responsible for discriminating the two groups were identified. The NOD macaques were mainly characterized by perturbations of fatty acid biosynthesis, ABC transport system, and amino acid metabolism (eg, aspartate, glycine, serine, and threonine metabolism). Interestingly, we found that eight altered CSF metabolites belonging to short-chain fatty acids and amino acids were also observed in the serum of NOD macaques (N=13 per group).

CONCLUSION

Our findings suggest that peripheral and central short-chain fatty acids and amino acids are implicated in the onset of depression.

Prophylactic ketamine alters nucleotide and neurotransmitter metabolism in brain and plasma following stress

Recently, we have shown that ketamine given prior to stress exposure protects against the development of depressive-like behavior in mice. These data suggest that it may be possible to prevent the induction of affective disorders before they develop by administering prophylactic pharmaceuticals, a relatively nascent and unexplored strategy for psychiatry. Here, we performed metabolomics analysis of brain and plasma following prophylactic ketamine treatment in order to identify markers of stress resilience enhancement. We administered prophylactic ketamine in mice to buffer against fear expression. Following behavioral analyses, untargeted metabolomic profiling was performed on both hemispheres of the prefrontal cortex (PFC) and the hippocampus (HPC), and plasma. We found that prophylactic ketamine attenuated learned fear. Eight metabolites were changed in the PFC and HPC upon ketamine treatment. Purine and pyrimidine metabolism were most significantly changed in the HPC, PFC, and, interestingly, plasma of mice two weeks after prophylactic administration. Moreover, most precursors to inhibitory neurotransmitters were increased whereas precursors to excitatory neurotransmitters were decreased. Strikingly, these long-term metabolomic changes were not observed when no stressor was administered. Our results suggest that prophylactic treatment differentially affects purine and pyrimidine metabolism and neurotransmission in brain and plasma following stress, which may underlie the long-lasting resilience to stress induced by a single injection of ketamine. These data may provide novel targets for prophylactic development, and indicate an interaction effect of prophylactic ketamine and stress. To our knowledge, this is the first study that identifies metabolomic alterations and biomarker candidates for prophylactic ketamine efficacy in mice.