Forced swimming and imipramine modify plasma and brain amino acid concentrations in mice

Creatine and taurine mixtures alleviate depressive-like behaviour in Drosophila melanogaster and mice via regulating Akt and ERK/BDNF pathways

We investigated the antidepressant effect of creatine (CRE) and taurine (TAU) mixtures on behavioural changes and biomarkers in stress-induced depression in Drosophila melanogaster and a mouse model. Following CRE/TAU mixture administration in the Drosophila model, depression-like state induced by vibration, locomotion, climbing activity, and survival rate were measured. The normal stress (NS) group demonstrated decreased movement than the control (CON) group; movements in the CRE/TAU-treated group (particularly 0.15/0.5%) returned to the CON levels. Antidepressant effects of CRE/TAU mixtures were confirmed in a depressive mouse model induced by chronic mild stress. In behavioural assessments, movement and sucrose preference of the CRE/TAU group increased to a similar level as in the positive control group; hippocampal catecholamine and serotonin levels increased significantly. Stress-related hormones (adrenocorticotropic and corticotropin-releasing hormones) and inflammatory factors (IL-1β, IL-6, and TNF-α) increased in the NS group but significantly decreased in the CRE/TAU-treated group. Brain signalling protein expression ratio of phosphorylated protein kinase B (p-Akt)/Akt, phosphorylated extracellular signal-regulated kinase (p-ERK)/ERK, and brain-derived neurotrophic factor (BDNF) significantly increased in the CRE/TAU-treated group. These results indicate that CRE/TAU-induced antidepressant effects are associated with increased behavioural patterns and downregulation of stress hormones and cytokines, mediated through Akt and ERK/BDNF pathways in vertebrate models.

Gut Microbiota: A Pivotal Hub for Polyphenols as Antidepressants

Polyphenols, present in a broad range of plants, have been thought to be responsible for many beneficial health effects, such as an antidepressant. Despite that polyphenols can be absorbed in the small intestine directly, most of them have low bioavailability and reach the large intestine without any modifications due to their complex structures. The interaction between microbial communities and polyphenols in the intestine is important for the latter to exert antidepressant effects. Gut microbiota can improve the bioavailability of polyphenols; in turn, polyphenols can maintain the intestinal barrier as well as the community of the gut microbiota in normal status. Furthermore, gut microbita catabolize polyphenols to more active, better-absorbed metabolites, further ameliorating depression through the microbial-gut-brain (MGB) axis. Based on this evidence, the review illustrates the potential role of gut microbiota in the processes of polyphenols or their metabolites acting as antidepressants and further envisions the gut microbiota as therapeutic targets for depression.

Amitriptyline at an Environmentally Relevant Concentration Alters the Profile of Metabolites Beyond Monoamines in Gilt-Head Bream

The antidepressant amitriptyline is a widely used selective serotonin reuptake inhibitor that is found in the aquatic environment. The present study investigates alterations in the brain and the liver metabolome of gilt-head bream (Sparus aurata) after exposure at an environmentally relevant concentration (0.2 µg/L) of amitriptyline for 7 d. Analysis of variance-simultaneous component analysis is used to identify metabolites that distinguish exposed from control animals. Overall, alterations in lipid metabolism suggest the occurrence of oxidative stress in both the brain and the liver-a common adverse effect of xenobiotics. However, alterations in the amino acid arginine are also observed. These are likely related to the nitric oxide system that is known to be associated with the mechanism of action of antidepressants. In addition, changes in asparagine and methionine levels in the brain and pantothenate, uric acid, and formylisoglutamine/N-formimino-L-glutamate levels in the liver could indicate variation of amino acid metabolism in both tissues; and the perturbation of glutamate in the liver implies that the energy metabolism is also affected. These results reveal that environmentally relevant concentrations of amitriptyline perturb a fraction of the metabolome that is not typically associated with antidepressant exposure in fish. Environ Toxicol Chem 2019;00:1-13. © 2019 SETAC.

Biomarkers for major depressive and bipolar disorders using metabolomics: A systematic review

Major depressive disorder (MDD) and bipolar disorder (BD) lack robust biomarkers useful for screening purposes in a clinical setting. A systematic review of the literature was conducted on metabolomic studies of patients with MDD or BD through the use of analytical platforms such as in vivo brain imaging, mass spectrometry, and nuclear magnetic resonance. Our search identified a total of 7,590 articles, of which 266 articles remained for full-text revision. Overall, 249 metabolites were found to be dysregulated with 122 of these metabolites being reported in two or more of the studies included. A list of biomarkers for MDD and BD established from metabolites found to be abnormal, along with the number of studies supporting each metabolite and a comparison of which biological fluids they were reported in, is provided. Metabolic pathways that may be important in the pathophysiology of MDD and BD were identified and predominantly center on glutamatergic metabolism, energy metabolism, and neurotransmission. Using online drug registries, we also illustrate how metabolomics can facilitate the discovery of novel candidate drug targets.

Plasma amino acid profile in major depressive disorder: Analyses in two independent case-control sample sets

Some amino acids act as neurotransmitters themselves, or are precursors of neurotransmitters. Previous studies reported inconsistent results regarding their changes in blood in major depressive disorder (MDD), which prompted us to examine plasma levels of amino acids and related molecules in two independent case-control sample sets. In total, 511 subjects were recruited. Sample set A consisted of 164 patients with MDD (147 currently depressed [dMDD]; 17 in remission, DSM-IV) and 217 healthy controls. Sample set B consisted of 65 patients (51 dMDD; 14 in remission) and 65 controls. Plasma amino acid levels were measured using high-performance liquid chromatography for set A and liquid chromatography/mass spectrometry for set B. We further analyzed the relationships between plasma amino acid levels and clinical variables. In sample set A, plasma asparagine, histidine+1-methylhistidine, methionine, phenylalanine, tryptophan, and tyrosine levels were decreased, while plasma glutamate and phosphoethanolamine were elevated in dMDD compared to controls (all P < 0.0005), even after correcting for multiple testing. Plasma leucine levels were associated with "psychic anxiety." In sample set B, glutamate and methionine levels were also altered in the same direction to that in sample set A (both P < 0.05). In the integrative analysis, plasma glutamate and methionine levels were found to be significantly associated with the diagnosis of MDD with small to medium effect sizes (both P < 1.0E-6). In conclusion, several amino acids and related molecules were altered in patients with MDD. Decreased methionine and increased glutamate levels were found consistently in the two sample sets, suggesting their involvement in MDD. Further investigations are warranted on the possible role of amino acids in the pathophysiology of MDD.

Single and chronic L-serine treatments exert antidepressant-like effects in rats possibly by different means

In the present study, the effects of both single (6 mmol L-serine/10 ml/kg orally administrated) and chronic (2% L-serine solution freely given for 28 days) treatments on depression-like behavior were evaluated in Wistar rats, representing the control, and Wistar Kyoto rats, representing an animal model of depression. Both single and chronic L-serine treatments decreased the duration of immobility, which is an index of a depressive-like state, in the forced swimming test in both strains. However, the decreases in the duration of immobility appear to be regulated differently by the different mechanisms involved in single and chronic L-serine treatments. In the prefrontal cortex and hippocampus, single L-serine treatment increased the concentrations of L-serine, but not D-serine, while chronic L-serine treatment increased those of D-serine, but not L-serine. These data suggest that the antidepressant-like effects of single and chronic L-serine treatments may have been induced by the increased L-serine and D-serine concentrations, respectively, in the brain. In addition, chronic L-serine treatment increased cystathionine concentrations in the hippocampus and prefrontal cortex in Wistar rats, but not in Wistar Kyoto rats, suggesting that Wistar Kyoto rats have an abnormality in the serine-cystathionine metabolic pathway. In conclusion, single and chronic L-serine treatments may induce antidepressant-like effects via the different mechanisms related to serine metabolism in the brain.

Effects of Diet Quality and Psychosocial Stress on the Metabolic Profiles of Mice

There has been an increasing interest in relationship between stress and diet. To address this relationship, we evaluated an animal model of depression: male C57BL/6J mice subjected to subchronic mild social defeat stress (sCSDS) for 10 consecutive days using male ICR mice under two different calorie-adjusted diets conditions-nonpurified (MF) and semipurified (AIN) diets made from natural and chemical ingredients mainly, respectively. Our previous study indicates that diet quality and purity affect stress susceptibility in sCSDS mice. We therefore hypothesized that there are some key peripheral metabolites to change stress-susceptible behavior. GC-MS metabolomics of plasma, liver, and cecal content were performed on four test groups: sCSDS + AIN diet (n = 7), sCSDS + MF diet (n = 6), control (no sCSDS) + AIN diet (n = 8), and control + MF diet (n = 8). Metabolome analyses revealed that the number of metabolites changed by food was larger than the number changed by stress in all tissues. Enrichment analysis of the liver metabolite set altered by food implies that stress-susceptible mice show increased glycolysis-related substrates in the liver. We found metabolites that were affected by stress (e.g., plasma and liver 4-hydroxyproline and plasma beta-alanine are higher in sCSDS than in control) and a stress × food interaction (e.g., plasma GABA is lower in sCSDS + AIN than in sCSDS + MF). Because functional compounds were altered by both stress and food, diet may be able to attenuate various stress-induced symptoms by changing metabolites in peripheral tissues.

Orally administered whole egg demonstrates antidepressant-like effects in the forced swimming test on rats

OBJECTIVE

Several studies have reported that vegetarian diets are associated with a higher prevalence of major depression. Therefore, we hypothesised that the consumption of animal products, especially eggs, may have positive effects on mental health, especially on major depression, because a previous study reported that egg consumption produces numerous beneficial effects in humans. The purpose of the present study was to evaluate the effects of chronic whole-egg treatment on depression-like behaviours in Wistar rats, a control strain, and Wistar Kyoto rats, an animal model of depression.

METHODS

In both the rats, either whole-egg solution (5 ml/kg) or distilled water (5 ml/kg) was orally administrated for 35 days. During these periods, the open-field test (OFT) was conducted on the 21st day, and a forced swimming test (FST) was enforced on the 27th and 28th days. On the 36th day, the plasma and brain were collected.

RESULTS

Chronic whole-egg treatment did not affect line crossing in the OFT, whereas it reduced the total duration of immobility in the FST on both strains. Furthermore, interestingly, the results indicated the possibility that whole-egg treatment elevated the incorporation of tryptophan into the brain, and the tryptophan concentration in the prefrontal cortex was actually increased by the treatment.

CONCLUSION

This study demonstrated that whole-egg treatment exerts an antidepressant-like effect in the FST. It is suggested that whole egg may be an excellent food for preventing and alleviating the conditions of major depression.

Amino acid metabolic dysfunction revealed in the prefrontal cortex of a rat model of depression

Major depressive disorder (MDD) is a debilitating mood disorder. However, the molecular mechanism(s) underlying depression remain largely unknown. Here, we applied a GC-MS-based metabonomic approach in the chronic unpredictable mild stress (CUMS) model, a well-established rodent model of depression, to investigate significant metabolic changes in the rat prefrontal cortex (PFC). Multivariate statistical analysis - including principal component analysis, partial least squares-discriminate analysis, and pair-wise orthogonal projections to latent structures discriminant - was applied to identify differential PFC metabolites between CUMS rats and healthy controls. As compared to healthy control rats, CUMS rats were characterized by lower levels of isoleucine and glycerol in combination with higher levels of N-acetylaspartate and β-alanine. These findings should provide insight into the pathophysiological mechanism(s) underlying MDD and preliminary leads relevant to diagnostic biomarker discovery for depression.

Long-term consumption of dried bonito dashi (a traditional Japanese fish stock) reduces anxiety and modifies central amino acid levels in rats

Dried bonito dashi, a traditional Japanese fish stock, enhances palatability of various dishes because of its specific flavor. Daily intake of dashi has also been shown to improve mood status such as tension-anxiety in humans. This study aimed at investigating beneficial effects of dashi ingestion on anxiety/depression-like behaviors and changes in amino acid levels in the brain and plasma in rats. Male Wistar rats were given either dried bonito dashi or water for long-term (29 days; Experiment 1) or single oral administration (Experiment 2). Anxiety and depression-like behaviors were tested using the open field and forced swimming tests, respectively. Concentrations of amino acids were measured in the hippocampus, hypothalamus, cerebellum, and jugular vein. During the long-term (29 days) consumption, rats given 2% dashi frequently entered the center zone and spent more time compared with the water controls in the open field test. However, the dashi was ineffective on depression-like behavior. In the hippocampus, concentrations of hydroxyproline, anserine, and valine were increased by dashi while those of asparagine and phenylalanine were decreased. In the hypothalamus, the methionine concentration was decreased. In a single oral administration experiment, the dashi (1%, 2% or 10%) showed no effects on behaviors. Significance was observed only in the concentrations of α-aminoadipic acid, cystathionine, and ornithine in the hippocampus. Dried bonito dashi is a functional food having anxiolytic-like effects. Daily ingestion of the dashi, even at lower concentrations found in the cuisine, reduces anxiety and alters amino acid levels in the brain.

Change in plasma levels of amino acid neurotransmitters and its correlation with clinical heterogeneity in early Parkinson's disease patients

BACKGROUND

The correlation between plasma amino acid (AA) neurotransmitters and clinical heterogeneity in early patients with Parkinson's disease (PD) is still poorly understood.

AIMS

To examine the plasma levels of AA neurotransmitters in early patients with PD and to evaluate their correlation with PD subtypes.

METHODS

Based on the predominant symptoms, fifty-one patients with PD were enrolled and divided into four subgroups: (1) akinetic-rigid type (ART), (2) tremor-dominant type (TDT), (3) postural instability/gait difficulty type (PIGD), and (4) mixed type (MT). Plasma levels of AA were measured by HPLC-RF, and their potential diagnostic practicality and their association with PD subtypes were evaluated by the receiver operating characteristic (ROC) and correlation analysis, respectively.

RESULTS

Patients with PD exhibited markedly lower levels of Asp, Glu, Tau, L-ser, and lower values of Glu/GABA ratio than healthy controls. The ROC analysis revealed their high sensitivity (77.1-87.5%) and specificity (58.8-88.2%). Furthermore, the glutamic acid (Glu), γ-aminobutyric acid (GABA) level in the PIGD subtype was increased as compared with other subtypes and was negatively correlated with the ART/PIGD ratio.

CONCLUSION

The decrease in plasma Asp, Glu, Tau, L-ser levels, and the value of Glu/GABA ratio may be helpful for early PD diagnosis. The elevated GABA level may be the biochemical basis for the specific symptoms of PIGD PD.

Neuropharmacological study of Dracocephalum moldavica L. (Lamiaceae) in mice: sedative effect and chemical analysis of an aqueous extract

ETHNOPHARMACOLOGICAL RELEVANCE

Dracocephalum moldavica is used as a tranquilizer and as remedy for nervous conditions relief in the Mexican traditional medicine. Despite its intensive use no literature reported neuropharmacological studies on Dracocephalum moldavica as yet.

AIM OF THE STUDY

The sedative, anxiolytic-like and antidepressant-like effects of the aqueous extract of aerial parts of Dracocephalum moldavica (Lamiaceae) (DM) were evaluated in behavioral models in mice. The general toxic effects of DM were evaluated as well as their chemical analysis was performed.

MATERIALS AND METHODS

DM effects were evaluated on pentobarbital-induced sleeping time (SPT), the hole-board (HBT), and the avoidance exploratory behavior (AEBT) tests and on the forced swimming test (FST). General activity and motor coordination were evaluated in the open field (OFT) and Rota-rod tests, respectively. The acute toxicity of DM was determinate by its LD(50) dose. The chemical analyses DM were performed by chromatographic and HPLC-ESI-MS techniques.

RESULTS

DM prolonged the pentobarbital-induced sleeping time, induced sedation in the HBT, decreased spontaneous activity and produced motor coordination impairment in mice. However, DM did not show anxiolytic effects in the AEBT or HBT and it was not effective in FST. The DM-treatment produced mortalities with LD(50)=470 mg/kg body weight. The HPLC-ESI-MS analysis of DM revealed that (acacetin, apigenin and luteolin)-7-O-β-D-(6″-O-malonyl)-glucoside derivates are the main compounds of DM.

CONCLUSIONS

DM induced sedative actions and a general inhibition of CNS activity observed by the decrease of animals' general activity, motor coordination and exploration.

Biochemical and structural characterization of mouse mitochondrial aspartate aminotransferase, a newly identified kynurenine aminotransferase-IV

Mammalian mAspAT (mitochondrial aspartate aminotransferase) is recently reported to have KAT (kynurenine aminotransferase) activity and plays a role in the biosynthesis of KYNA (kynurenic acid) in rat, mouse and human brains. This study concerns the biochemical and structural characterization of mouse mAspAT. In this study, mouse mAspAT cDNA was amplified from mouse brain first stand cDNA and its recombinant protein was expressed in an Escherichia coli expression system. Sixteen oxo acids were tested for the co-substrate specificity of mouse mAspAT and 14 of them were shown to be capable of serving as co-substrates for the enzyme. Structural analysis of mAspAT by macromolecular crystallography revealed that the cofactor-binding residues of mAspAT are similar to those of other KATs. The substrate-binding residues of mAspAT are slightly different from those of other KATs. Our results provide a biochemical and structural basis towards understanding the overall physiological role of mAspAT in vivo and insight into controlling the levels of endogenous KYNA through modulation of the enzyme in the mouse brain.

5-HT(1A) receptor and apoptosis contribute to interferon-α-induced "depressive-like" behavior in mice

Interferon-α (IFN-α)-induced "depressive-like" behavior is a major limitation for the treatment of hepatitis C virus (HCV), especially for patients with psychiatric disorders. Recently, serotonin 1A (5-HT(1A)) receptor and cellular apoptosis are involved in mechanism(s) contributing to depression. To gain insight into this mechanism(s), we used C57BL/6J mice to examine the impact of IFN-α on the modulation of 5-HT(1A) receptor and cellular apoptosis and their relationship. Our results showed that repeated administration of IFN-α (6 MIU/kg, s.c.) induced "depressive-like" behavior of mice in the forced swim test, tail suspension test and sucrose preference test. Besides, the depressive mice exhibited a notable downregulation of 5-HT(1A) receptor and upregulation of cleaved caspase-3 and Bax/Bcl-2 ratio. These changes could be blocked by the 5-HT(1A) receptor agonist 8-OH-DPAT (0.5 mg/kg, i.p., 30 min before IFN-α administration), but not by the standard antidepressant imipramine (10 mg/kg, i.p., 30 min before IFN-α administration) although both of them could ameliorate the depressive-like behavior of mice. These findings indicated that repeated injection with IFN-α provoked "depressive-like" behavior through cellular apoptosis, which could be ameliorated by the activation of 5-HT(1A) receptor.

Anti-depressant effects of Xiaoyaosan on rat model of chronic unpredictable mild stress: a plasma metabonomics study based on NMR spectroscopy

OBJECTIVES

To investigate the antidepressant effects of Xiaoyaosan (XYS) in a chronic unpredictable mild stress (CUMS) depression model.

METHODS

The changes in behaviour and plasma metabolic profiles were investigated after four-week CUMS exposure and treatment. Drugs were administered during the four-week period of CUMS, with the healthy group serving as negative controls, and the fluoxetine and venlafaxine groups serving as positive controls. Plasma samples were collected at 28th day, and the plasma metabolic profiling was measured using NMR, followed by multivariate analysis.

KEY FINDINGS

Exposure to CUMS for four weeks caused depression-like behaviour in rats, as indicated by significant decreases in weight gain, sucrose consumption and locomotor activity. Eleven potential biomarkers, including seven in the Carr-Purcell-Meiboom-Gill spectra, five in the diffusion-edited spectra, and one in both were identified. It was found that trimethylamine-N-oxide, alanine, β-hydroxybutyrate, valine, leucine/isoleucine, low-density lipoprotein/very low-density lipoprotein and lipids were lower and phosphatidylcholine, high-density lipoprotein, choline and N-acetyl glycoproteins were higher in CUMS-treated rats, as compared with controls. XYS significantly suppressed behavioural changes and attenuated plasma metabolite changes.

CONCLUSIONS

XYS produced an obvious antidepressant effect, and the metabonomic approach benefits estimation of the pharmacodynamic action of traditional Chinese medicine prescriptions.

Molecular identification of carnosine synthase as ATP-grasp domain-containing protein 1 (ATPGD1)

Carnosine (beta-alanyl-L-histidine) and homocarnosine (gamma-aminobutyryl-L-histidine) are abundant dipeptides in skeletal muscle and brain of most vertebrates and some invertebrates. The formation of both compounds is catalyzed by carnosine synthase, which is thought to convert ATP to AMP and inorganic pyrophosphate, and whose molecular identity is unknown. In the present work, we have purified carnosine synthase from chicken pectoral muscle about 1500-fold until only two major polypeptides of 100 and 90 kDa were present in the preparation. Mass spectrometry analysis of these polypeptides did not yield any meaningful candidate. Carnosine formation catalyzed by the purified enzyme was accompanied by a stoichiometric formation, not of AMP, but of ADP, suggesting that carnosine synthase belongs to the "ATP-grasp family" of ligases. A data base mining approach identified ATPGD1 as a likely candidate. As this protein was absent from chicken protein data bases, we reconstituted its sequence from a PCR-amplified cDNA and found it to fit with the 100-kDa polypeptide of the chicken carnosine synthase preparation. Mouse and human ATPGD1 were expressed in HEK293T cells, purified to homogeneity, and shown to catalyze the formation of carnosine, as confirmed by mass spectrometry, and of homocarnosine. Specificity studies carried out on all three enzymes were in agreement with published data. In particular, they acted with 15-25-fold higher catalytic efficiencies on beta-alanine than on gamma-aminobutyrate. The identification of the gene encoding carnosine synthase will help for a better understanding of the biological functions of carnosine and related dipeptides, which still remain largely unknown.

Dietary l-tyrosine alleviates the behavioral alterations induced by social isolation stress in mice

Chronic stress induces abnormal mental state and behavior, and can be a risk factor for mental disorders. Although it is reported that l-tyrosine, an amino acid that is a precursor of catecholamine synthesis, alleviated the change of cognition and behavior induced by acute stress, knowledge about its effects on chronic stress is limited. In the present study, the effects of dietary l-tyrosine on behavioral alteration induced by chronic stress were investigated by employing a social isolation stress model in mice. Social isolation stress increased locomotor activity in both the home cage and open field. These increases of locomotor activity were suppressed by dietary l-tyrosine. Moreover, l-tyrosine increased both the concentration and turnover rate of norepinephrine metabolites. These findings partly suggest the availability of dietary l-tyrosine for psychic dysfunctions induced by chronic stress.

Antidepressants induce regionally discrete, sex-dependent changes in brain's glutamate content

Growing evidence suggests the involvement of glutamate in mood disorders and in the response to antidepressants. However, there is no information regarding a hypothesized sex-dependent glutamatergic modulation following treatment in animal models of depression. We comparatively assayed in male and female Flinders and control Sprague-Dawley rats glutamate and aspartate tissue levels in the prefrontal cortex, hippocampus and nucleus accumbens following 14-day treatment with either 10mg/kg clomipramine or mirtazapine, intraperitoneally. Clomipramine increased cortical glutamate in both sexes and hippocampal glutamate only in female Flinders rodents. Mirtazapine had no effect on cortical glutamate content but increased hippocampal glutamate in both Flinders sexes. Neither mirtazapine nor clomipramine altered glutamate levels in the nucleus accumbens. There were no any significant differences in aspartate levels. However, in control male SD rats clomipramine and mirtazapine significantly decreased cortical aspartate levels. Our results indicate that two different types of established antidepressants induce a brain region-specific effect on glutamate content. This effect is also characterized by sex-dependent differences mainly in the hippocampus, highlighting a differentiated response of glutamate to distinct antidepressants.