LC-MS/MS-based quantification of tryptophan metabolites and neurotransmitters in the serum and brain of mice

The Impact of Depression on Detrimental Changes in Bone Microstructure in Female Mice

Background

Several clinical studies have examined the connection between depression and bone loss, but the cause-and-effect relationship between the two conditions, especially in animal models, is not well-studied.

Methods

A total of 32 female mice were, randomly divided into control group (CON, n=19) and depression group (DEP, n=13). The mice in the DEP group were subjected to 21 consecutive days of restraint stress, following depressive-like behaviors were assessment. The femurs were collected using Micro-Computed Tomography (μCT) and histochemical staining. In parallel, levels of serotonin-related proteins in the brain were measured using Western blot analysis, and sex hormone profiles were determined through liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS).

Results

The mice in the DEP group exhibited clear signs of depressive-like behaviors and an increase in serotonin transporter levels (t=-2.435, P< 0.05). In comparison to the CON mice, the DEP mice showed a decrease in bone mineral density (t =3.741, P< 0.05), bone surface area density (t =8.009, P<0.01), percent bone volume (t =4.293, P< 0.05), trabecular number (t =5.844, P<0.01), and connected density (t =11.000, P< 0.05). Additionally, there was an increase in trabecular separation (t =-7.436, P<0.01) in DEP mice. Furthermore, the DEP mice displayed a significant reduction in serum estrogen levels (t =4.340, P< 0.05) and changes in its metabolite (t =-3.325, P< 0.05), while the levels of androgens remained unchanged.

Conclusion

The restraint stress not only led to the development of depressive-like behaviors but also disrupted the estrogen metabolism pathway, resulting in damage to bone mass and microstructure in female mice. These findings suggest that stress-induced depression may pose a risk for bone loss in female mice by altering estrogen metabolism pathways.

Derivative spectrophotometry-assisted determination of tryptophan metabolites emerges host and intestinal flora dysregulations during sepsis

Sepsis is a life-threatening condition characterized by organ dysfunction resulting from a dysregulated host response to infection. Dysregulated tryptophan (TRP) metabolites serve as significant indicators for endogenous immune turnovers and abnormal metabolism in the intestinal microbiota during sepsis. Therefore, a high coverage determination of TRP and its metabolites in sepsis is beneficial for the diagnosis and prognosis of sepsis, as well as for understanding the underlying mechanism of sepsis development. However, similar structures in TRP metabolites make it challenging for separation and metabolite identification. Here, high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD) was developed to determine TRP metabolites in rat serum. The first-order derivative spectrophotometry of targeted metabolites in the serum was investigated and proved to be promising for chromatographic peak annotation across different columns and systems. The established method separating the targeted metabolites was optimized and validated to be sensitive and accurate. Application of the method revealed dysregulated TRP metabolites, associated with immune disorders and NAD + metabolism in both the host and gut flora in septic rats. Our findings indicate that the derivative spectrophotometry-assisted method enhances metabolite identifications for the chromatographic systems based on DAD detectors and holds promise for precision medicine in sepsis.

Electroacupuncture Promotes Liver Regeneration by Activating DMV Acetylcholinergic Neurons-Vagus-Macrophage Axis in 70% Partial Hepatectomy of Mice

Lack of liver regenerative capacity is the primary cause of hepatic failure and even mortality in patients undergoing hepatectomy, with no effective intervention strategies currently available. Therefore, identifying efficacious interventions to enhance liver regeneration is pivotal for optimizing clinical outcomes. Recent studies have demonstrated that vagotomy exerts an inhibitory effect on liver regeneration following partial hepatectomy, thereby substantiating the pivotal role played by the vagus nerve in the process of liver regeneration. In recent years, electroacupuncture (EA) has emerged as a non-invasive technique for stimulating the vagus nerve. However, EA on hepatic regeneration remains uncertain. In this study, a 70% partial hepatectomy (PH) mouse model is utilized to investigate the effects of EA on acute liver regeneration and elucidate its underlying molecular mechanisms. It is observed that EA at ST36 acutely activated cholinergic neurons in the dorsal motor nucleus of the vagus nerve (DMV), resulting in increased release of acetylcholine from hepatic vagal nerve endings and subsequent activation of IL-6 signaling in liver macrophages. Ultimately, these events promoted hepatocyte proliferation and facilitated liver regeneration. These findings provide insights into the fundamental brain-liver axis mechanism through which EA promotes liver regeneration, offering a novel therapeutic approach for post-hepatectomy liver regeneration disorders.

Sildenafil, alone and in combination with imipramine or escitalopram, display antidepressant-like effects in an adrenocorticotropic hormone-induced (ACTH) rodent model of treatment-resistant depression

BACKGROUND

Major depressive disorder (MDD) represents a challenge with high prevalence and limited effectiveness of existing treatments, particularly in cases of treatment-resistant depression (TRD). Innovative strategies and alternative drug targets are therefore necessary. Sildenafil, a selective phosphodiesterase type 5 (PDE5) inhibitor, is known to exert neuroplastic, anti-inflammatory, and antioxidant properties, and is a promising antidepressant drug candidate.

AIM

To investigate whether sildenafil monotherapy or in combination with a known antidepressant, can elicit antidepressant-like effects in an adrenocorticotropic hormone (ACTH)-induced rodent model of TRD.

METHODS

ACTH-naïve and ACTH-treated male Sprague-Dawley (SD) rats received various sub-acute drug treatments, followed by behavioural tests and biochemical analyses conversant with antidepressant actions.

RESULTS

Sub-chronic ACTH treatment induced significant depressive-like behaviour in rats, evidenced by increased immobility during the forced swim test (FST). Sub-acute sildenafil (10 mg/kg) (SIL-10) (but not SIL-3), and combinations of imipramine (15 mg/kg) (IMI-15) and sildenafil (3 mg/kg) (SIL-3) or escitalopram (15 mg/kg) (ESC-15) and SIL-3, exhibited significant antidepressant-like effects. ACTH treatment significantly elevated hippocampal levels of brain-derived neurotrophic factor (BDNF), serotonin, norepinephrine, kynurenic acid (KYNUA), quinolinic acid (QUINA), and glutathione. The various mono- and combined treatments significantly reversed some of these changes, whereas IMI-15 + SIL-10 significantly increased glutathione disulfide levels. ESC-15 + SIL-3 significantly reduced plasma corticosterone levels.

CONCLUSION

This study suggests that sildenafil shows promise as a treatment for TRD, either as a stand-alone therapy or in combination with a traditional antidepressant. The neurobiological mechanism underlying the antidepressant-like effects of the different sildenafil mono- and combination therapies reflects a multimodal action and cannot be explained in full by changes in the individually measured biomarker levels.

Simultaneous detection of norepinephrine and 5-hydroxytryptophan using poly-alizarin/multi-walled carbon nanotubes-graphene modified carbon fiber microelectrode array sensor

Multi-walled carbon nanotubes, graphene and alizarin polymer composites coated carbon fiber microelectrode array sensor (p-AZ/MWCNT-GR/CFMEA) was constructed and used for the simultaneous detection of norepinephrine (NE) and 5-hydroxytryptophan (5-HT). The morphology and structural characteristics of sensor are characterized using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Its electrochemical behavior has been studied with cyclic voltammetry and electrochemical impedance spectroscopy. The sensor exhibits excellent electrochemical activity for the oxidation of NE and 5-HT, two well separated oxidation peaks with the peak potential difference of 220 mV are observed on the cyclic voltammogram. NE and 5-HT both show two electrons and two protons electrochemical reaction on the p-AZ/MWCNT-GR/CFMEA. Under the optimized experiment conditions, the linear ranges of the sensor for NE and 5-HT are 0. 08- 8 μM and 0. 1-20 μM with detection limits of 4. 22 nM and 14. 2 nM (S/N = 3), respectively. In addition, the microsensor array show good reproducibility, stability and selectivity for the determination of NE and 5-HT. Finally, the p-AZ/MWCNT-GR/CFMEA is applied to the simultaneous detection of NE and 5-HT in human serum samples and macrophages.

Dysfunction of neurotransmitter metabolism is associated with the severity of depression in first-diagnosed, drug-naïve depressed patients

BACKGROUND & AIMS

Biochemical changes of neurotransmitters underlying major depressive disorder (MDD) are unknown. This study preliminarily explored the association between neurotransmitters with MDD and the possibility of objective laboratory prediction of neurotransmitter involvement in MDD.

METHODS

A total of 87 first-diagnosed, drug-naïve patients with depression and 50 healthy controls (HCs) were included in the cross-sectional study. The levels and turnovers of neurotransmitters (glutamine (GLN), glutamic acid (GLU), γ-2Aminobutiric acid (GABA), kainate (KA), vanillylmandelic acid (VMA), 3-methoxy 4-hydroxyphenyl ethylene glycol (MHPG), noradrenaline (NE), homovanillic acid (HVA), dihydroxy-phenyl acetic acid (DOPAC), dopamine (DA), tryptophane (TRP), kynurenine (KYN), serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA)) were determined and the confounding factors were adjusted. Then a correlation and a predictive analysis towards neurotransmitters for MDD were performed.

RESULTS

After adjusting confounding factors, GLU (OR = 1.159), (GLU+ GABA)/GLN (OR = 1.217), DOPAC (OR = 1.106), DOPAC/DA (OR = 1.089) and (DOPAC+ HVA)/DA (OR = 1.026) enacted as risk factors of MDD, while KYN (OR = 0.992) was a protective factor. GABAergic and TRPergic pathways were associated with severity of depressive and anxiety symptoms in patients with depression. The predictive model for MDD (AUC = 0.775, 95%CI 0.683-0.860) consisted of KYN (OR = 0.990) and (GLU + GABA)/GLN (OR = 4.101).

CONCLUSIONS

First-diagnosed, drug-naïve depression patients showed abnormal neurotransmitter composition. GLU, (GLU + GABA)/GLN, DOPAC, DOPAC/DA and (DOPAC + HVA)/DA were risk factors of MDD, while KYN was a protective factor. GABAergic and TRPergic pathways were correlated with MDD clinical characteristics. KYN and (GLU + GABA)/GLN may have a predictive value for MDD.

Effects of continuous and pulse lead exposure on the swimming behavior of tadpoles revealed by brain-gut axis analysis

Lead (Pb) is present in aquatic environments with a continuous or pulse form due to the regular or irregular discharge of wastewater. These two modes of exposure result in different toxicological effects on aquatic animals. To compare the effects of Pb exposure mode on the swimming behavior of amphibian larvae, this study proposed a combination method to examine the brain-gut axis (gut bacteria, histopathology, metabolomics, and ethology) in order to evaluate the ecotoxic differences in Pelophylax nigromaculatus tadpoles (Gs 21-28) when exposed to continuous (CE100) versus pulse exposure (PE100) of environmental concentrations of Pb (100 μg/L). The results showed that: 1) CE100 significantly decreased the movement distance and swimming activity of the tadpoles compared to PE100 and the control, while there were no significant differences between the control group and PE100. 2) At the phyla level, compared to PE100, CE100 treatment significantly decreased the abundance of Actinobacteria, Firmicutes, Proteobacteria, and Bacteroidetes and increased the abundance of Fusobacteria in the gut. At the genus level, compared to PE100, CE100 significantly increased the abundance of U114 and decreased the abundance of Anaerorhabdus, Exiguobacterium and Microbacterium. 3) Compared to PE100, CE100 changed the metabolites of the brain-gut axis pathway, such as quinolinic acid, L-valine, L-dopa, L-histidine, urocanic acid, L-threonine, γ-aminobutyric acid (GABA), L-glutamate (Glu), acetylcholine (Ach), L-tyrosine (Tyr), L-tryptophan (Trp), and levodopa (DOPA). 4) CE100 and PE100 played a repressive role in the histidine metabolism and tyrosine metabolism pathways and played a promoting role in the purine metabolism and pyrimidine metabolism pathways. This study provides a method for evaluating the toxic effects of heavy metal exposure via two different exposure modes (pulse versus continuous) which tadpoles may encounter in the natural environment from a combined study examining the brain-gut axis.

Effects of different chronic restraint stress periods on anxiety- and depression-like behaviors and tryptophan-kynurenine metabolism along the brain-gut axis in C57BL/6N mice

Chronic restraint stress (CRS) is a widely used stimulus to induce anxiety- and depression-like behaviors, linked to alterations in tryptophan-kynurenine (TRP-KYN) metabolism in animals. This study assessed the effects of different CRS periods on anxiety- or depression-like behaviors and TRP-KYN metabolism along brain-gut axis in C57BL/6N mice. Results showed that one-week CRS decreased the open arm entries of mice in elevated plus maze and delayed latency of feeding in novelty suppressed feeding test. Four-week CRS reduced sucrose preference, increases forced swimming immobility time, and also induced anxiety-like behaviors of mice. UPLC-MS/MS analysis revealed decreased levels of the neurotoxic 3-hydroxykynurenine (3-HK) and quinolinic acid (QA), and an increase in the neuroprotective kynurenic acid (KA) in the hippocampus of one-week CRS mice; meanwhile, four-week CRS mice displayed a reduction in KA and increases in 3-HK and QA. In the colon, both one-week and four-week CRS mice exhibited significant reductions in 3-HK and QA, with a marked increase of KA exclusively in four-week CRS mice. Briefly, one-week CRS only induced anxiety-like behaviors with hippocampal neuroprotection in TRP-KYN metabolism, whereas four-week CRS caused anxiety- and depression-like behaviors with neurotoxicity. In the colon, during both CRS periods, KYN was metabolized in the direction of NAD+ production. However, four-week CRS triggered intestinal inflammation risk with increased KA. Summarily, slightly short-term stress has beneficial effects on mice, while prolonged chronic stress can lead to pathological changes. This study offers valuable insights into stress-induced emotional disturbances.

Systemic and Brain Pharmacokinetics of Milnacipran in Mice: Comparison of Intraperitoneal and Intravenous Administration

Milnacipran is a dual serotonin and norepinephrine reuptake inhibitor, clinically used for the treatment of major depression or fibromyalgia. Currently, there are no studies reporting the pharmacokinetics (PK) of milnacipran after intraperitoneal (IP) injection, despite this being the primary administration route in numerous experimental studies using the drug. Therefore, the present study was designed to investigate the PK profile of IP-administered milnacipran in mice and compare it to the intravenous (IV) route. First a liquid chromatography-mass spectrometry (LC-MS/MS) method was developed and validated to accurately quantify milnacipran in biological samples. The method was used to quantify milnacipran in blood and brain samples collected at various time-points post-administration. Non-compartmental and PK analyses were employed to determine key PK parameters. The maximum concentration (Cmax) of the drug in plasma was at 5 min after IP administration, whereas in the brain, it was at 60 min for both routes of administration. Curiously, the majority of PK parameters were similar irrespective of the administration route, and the bioavailability was 92.5% after the IP injection. These findings provide insight into milnacipran's absorption, distribution, and elimination characteristics in mice after IP administration for the first time and should be valuable for future pharmacological studies.

Dose-dependent action of cordycepin on the microbiome-gut-brain-adipose axis in mice exposed to stress

The high risk for anxiety and depression among individuals with stress has become a growing concern globally. Stress-related mental disorders are often accompanied by symptoms of metabolic dysfunction. Cordycepin is a Chinese herbal medicine commonly used for its metabolism-enhancing effects. We aimed to investigate the dose-dependent effects of cordycepin on psycho-metabolic disorders induced by stress. Our behavioral tests revealed that 12.5 mg/kg cordycepin by oral gavage significantly attenuated the anxiety- and depression-like behaviors induced by stress in mice. At 25 mg/kg, cordycepin restored the reduced weight and cell size of adipose tissues caused by stress. Besides ameliorating the metabolic dysbiosis of gut microbiota due to stress, cordycepin significantly reduced the elevated contents of 5-hydroxyindoleacetic acid in the serum and prefrontal cortex at 12.5 mg/kg and reversed the decrease in adipose induced by stress at 25 mg/kg. Correlation analyses further revealed that 12.5 mg/kg cordycepin reversed stress-induced changes in the intestinal microbiome of NK4A214_group and decreased serum Myristic acid and PC(15:0/18:1(11Z)) and cytokines, such as IFN-γ and IL-1β. 25 mg/kg cordycepin reversed stress-induced changes in the abundances of Prevoteaceae_UCG-001 and Desulfovibrio, increased serum L-alanine level, and decreased serum Inosine-5'-monophosphate level. Cordycepin thereby ameliorated the anxiety- and depression-like behaviors as well as disturbances in the adipose metabolism of mice exposed to stress. Overall, these findings offer evidence indicating that the prominent effects of cordycepin in the brain and adipose tissues are dose dependent, thus highlight the importance of evaluating the precise therapeutic effects of different cordycepin doses on psycho-metabolic diseases.

Engineered Selenium/Human Serum Albumin Nanoparticles for Efficient Targeted Treatment of Parkinson's Disease via Oral Gavage

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the degeneration of dopamine (DA) neurons in the midbrain substantia nigra pars compacta (SNpc). While existing therapeutic strategies can alleviate PD symptoms, they cannot inhibit DA neuron loss. Herein, a tailor-made human serum albumin (HSA)-based selenium nanosystem (HSA/Se nanoparticles, HSA/Se NPs) to treat PD that can overcome the intestinal epithelial barrier (IEB) and blood-brain barrier (BBB) is described. HSA, a transporter for drug delivery, has superior biological characteristics that make it an ideal potential drug delivery substance. Findings reveal that HSA/Se NPs have lower toxicity and higher efficacy than other selenium species and the ability to overcome the IEB and BBB to enrich DA neurons, which then protect MN9D cells from MPP+-induced neurotoxicity and ameliorate both behavioral deficits and DA neuronal death in MPTP-model mice. Thus, a therapeutic drug delivery system composed of orally gavaged HSA/Se NPs for the treatment of PD is described.

Attenuation of Chronic Stress-Induced Depressive-like Symptoms by Fish Oil via Alleviating Neuroinflammation and Impaired Tryptophan Metabolism in Aging Rats

The prevalence of depression is increasing, and geriatric depression, in particular, is difficult to recognize and treat. Depression in older adults is often accompanied by neuroinflammation in the central nervous system (CNS). Neuroinflammation affects the brain's physiological and immune functions through several pathways and induces depressive symptoms. This study investigated the relationship among depression, neuroinflammation, and fish oil supplementation. Thirty-six male Sprague-Dawley rats were used in an aging-related depression animal model to simulate geriatric depression. Cognitive function, depressive-like symptoms, peripheral nervous system and CNS inflammation status, and the tryptophan-related metabolic pathway were analyzed. The geriatric depression animal model was associated with depressive-like behaviors and cognitive impairment. The integrity of the blood-brain barrier was compromised, resulting in increased expression of ionized calcium-binding adapter molecule 1 and the glial fibrillary acidic protein in the brain, indicating increased neuroinflammation. Tryptophan metabolism was also negatively affected. The geriatric-depressive-like rats had high levels of neurotoxic 5-hydroxyindoleacetic acid and kynurenine in their hippocampus. Fish oil intake improved depressive-like symptoms and cognitive impairment, reduced proinflammatory cytokine expression, activated the brain's glial cells, and increased the interleukin-10 level in the prefrontal cortex. Thus, fish oil intervention could ameliorate abnormal neurobehaviors and neuroinflammation and elevate the serotonin level in the hippocampus.

Diagnostic value of serum neuroactive substances in the acute exacerbation of chronic obstructive pulmonary disease complicated with depression

We aimed to investigate the potential diagnostic value of five serum neuroactive substances in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) complicated with depression. A total of 103 patients with AECOPD were enrolled between August 2020 and August 2021. All patients were assessed using a self-rating depression scale and divided into AECOPD with or without depression groups. Baseline data and serum neuroactive substance levels were compared between the two groups. Logistic regression was used to identify the risk factors. The diagnostic performance of neuroactive substances was evaluated using receiver operating characteristic (ROC) curves. Patients with AECOPD complicated with depression exhibited higher partial pressure of CO2 values and higher chronic obstructive pulmonary disease assessment test (CAT) scores. An elevated proportion of patients with more than two acute exacerbations (AEs) in the previous year was observed in this patient group (all P < 0.001). The CAT score and number of AEs during the previous year were identified as independent risk factors for AECOPD complicated with depression. No significant differences were observed in the levels of aspartic acid and glutamate between the two groups (P > 0.05). Serum γ-aminobutyric acid (GABA) and glycine (Gly) levels were decreased. In contrast, serum nitric oxide (NO) levels were increased in the AECOPD complicated with the depression group (P < 0.05). Serum GABA and Gly levels exhibited a negative correlation, and NO levels positively correlated with the number of AEs in the previous year and the CAT score. The area under the ROC curve values for GABA, Gly, and NO were 0.755, 0.695, and 0.724, respectively. Serum GABA exhibited a sensitivity of 85.1% and a specificity of 58.9%, below the cut-off value of 4855.98 nmol/L. Serum GABA, Gly, and NO may represent potential biomarkers for AECOPD complicated with depression.

Preparation of self-supporting vertically/horizontally grown graphene microelectrodes for neurotransmitter determination

The development of microelectrodes for the rapid in situ detection of neurotransmitters and their metabolic levels in human biofluids has considerable significance in biomedical research. In this study, self-supported graphene microelectrodes with B-doped, N-doped, and B- and N-co-doped vertical graphene (BVG, NVG, and BNVG, respectively) nanosheets grown on horizontal graphene (HG) were fabricated for the first time. The high electrochemical catalytic activity of BVG/HG on monoamine compounds was explored by investigating the influence of B and N atoms and the VG layer thickness on the response current of neurotransmitters. Quantitative analysis using the BVG/HG electrode in a blood-like environment with pH 7.4 indicated that the linear concentration ranges were 1-400 and 1-350 μM for dopamine (DA) and serotonin (5-HT), with limits of detection (LODs) of 0.271 and 0.361 μM, respectively. For tryptophan (Trp), the sensor measured a wide linear concentration range of 3-1500 μM over a wide pH range of 5.0-9.0, with the LOD fluctuating between 0.58 and 1.04 μM. Furthermore, the BVG/HG microelectrodes could be developed as needle- and pen-type sensors for the detection of DA, 5-HT, and Trp in human blood and gastrointestinal secretion samples.

A Reliable Method Based on Liquid Chromatography-Tandem Mass Spectrometry for the Simultaneous Quantification of Neurotransmitters in Caenorhabditis elegans

Neurotransmitters like dopamine (DA), serotonin (SRT), γ-aminobutyric acid (GABA) and acetylcholine (ACh) are messenger molecules that play a pivotal role in transmitting excitation between neurons across chemical synapses, thus enabling complex processes in the central nervous system (CNS). Balance in neurotransmitter homeostasis is essential, and altered neurotransmitter levels are associated with various neurological disorders, e.g., loss of dopaminergic neurons (Parkinson's disease) or altered ACh synthesis (Alzheimer's disease). Therefore, it is crucial to possess adequate tools to assess precise neurotransmitter levels, and to apply targeted therapies. An established in vivo model to study neurotoxicity is the model organism Caenorhabditis elegans (C. elegans), as its neurons have been well characterized and functionally are analogous to mammals. We have developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method including a sample preparation assuring neurotransmitter stability, which allows a simultaneous neurotransmitter quantification of DA, SRT, GABA and ACh in C. elegans, but can easily be applied to other matrices. LC-MS/MS combined with isotope-labeled standards is the tool of choice, due to its otherwise unattainable sensitivity and specificity. Using C. elegans together with our analytically validated and verified method provides a powerful tool to evaluate mechanisms of neurotoxicity, and furthermore to identify possible therapeutic approaches.

Metabolic Fingerprints of Effective Fluoxetine Treatment in the Prefrontal Cortex of Chronically Socially Isolated Rats: Marker Candidates and Predictive Metabolites

The increasing prevalence of depression requires more effective therapy and the understanding of antidepressants' mode of action. We carried out untargeted metabolomics of the prefrontal cortex of rats exposed to chronic social isolation (CSIS), a rat model of depression, and/or fluoxetine treatment using liquid chromatography-high resolution mass spectrometry. The behavioral phenotype was assessed by the forced swim test. To analyze the metabolomics data, we employed univariate and multivariate analysis and biomarker capacity assessment using the receiver operating characteristic (ROC) curve. We also identified the most predictive biomarkers using a support vector machine with linear kernel (SVM-LK). Upregulated myo-inositol following CSIS may represent a potential marker of depressive phenotype. Effective fluoxetine treatment reversed depressive-like behavior and increased sedoheptulose 7-phosphate, hypotaurine, and acetyl-L-carnitine contents, which were identified as marker candidates for fluoxetine efficacy. ROC analysis revealed 4 significant marker candidates for CSIS group discrimination, and 10 for fluoxetine efficacy. SVM-LK with accuracies of 61.50% or 93.30% identified a panel of 7 or 25 predictive metabolites for depressive-like behavior or fluoxetine effectiveness, respectively. Overall, metabolic fingerprints combined with the ROC curve and SVM-LK may represent a new approach to identifying marker candidates or predictive metabolites for ongoing disease or disease risk and treatment outcome.

Tryptophan-kynurenine metabolic characterization in the gut and brain of depressive-like rats induced by chronic restraint stress

Accumulating evidence revealed the role of tryptophan (TRP) metabolism, especially its kynurenine pathway (KP), in the communication along the gut-brain axis. However, the underlying characterization of such interaction was not precise. In the present study, the rat depression model was induced by chronic restraint stress (CRS). After depression behavior tests, seven segments (cortex, hippocampus, striatum, hypothalamus, serum, cecum, and colon) along the gut-brain axis were collected to characterize their KP metabolism. mRNA expression of IL-1β, IFN-γ, IL-10 and indoleamine 2,3-dioxygenase 1 (IDO1) enzyme revealed a general inflammatory response and region-specific activated IDO1 along the gut-brain axis. Determination of KP metabolites and enzymes displayed a general KP activation with region-specificity, especially in the hippocampus and colon, where the changes were more pronounced. KYN and 3-HK were increased dramatically along the gut-brain axis; hippocampal KA revealed a significant decrease while colonic KA showed a notable increase, evidenced by the same alternation trends of the corresponding enzymes. The expression of quinolinic acid phosphoribosyltransferase (QPRT), the crucial enzyme to produce NAD⁺ from QA, was significantly upregulated in the gut but not changed in the brain. Pearson's correlation analysis suggested that kynurenine (KYN), 3-hydroxycaninuric acid (3-HK), serotonin (5-HT), TRP and kynurenic acid (KA) significantly correlated with depressive behaviors in rats. Furthermore, western blot analysis on nod-like receptor protein 3/2 (NLRP3/NLRP2) inflammasome signaling displayed that NLRP3 and cleaved IL-1β/caspase-1 were significantly activated in the hippocampus and colon of CRS rats. However, NLRP2 was only activated in the hippocampus. These results revealed CRS induced inflammatory responses along the brain-gut axis of rats might be controlled through the NLRP3/NLRP2 inflammasome signaling pathway, which may be the underlying regulator for CRS-induced TRP-KYN metabolic changes. This study provides a new experimental background for developing stress-related health products.

Network pharmacology, molecular docking, and experimental validation to explore the potential mechanism of Long Mu Qing Xin mixture for the treatment of attention deficit hyperactivity disorder

Background: Long Mu Qing Xin Mixture (LMQXM) has shown potentially positive effects in alleviating attention deficit hyperactivity disorder (ADHD); however, the action mechanism is still not fully understood. This study aimed to predict the potential mechanism of LMQXM for ADHD using network pharmacology and molecular docking, which were then validated using animal experiments.

Methods: Network pharmacology and molecular docking techniques were used to predict the core targets and potential pathways of LMQXMQ for ADHD, and KEGG pathway enrichment analysis revealed the potential significance of dopamine (DA) and cyclic adenosine monophosphate (cAMP) signaling pathways. To verify the hypothesis, we conducted an animal experiment. In the animal experiment, the young spontaneously hypertensive rats (SHRs) were randomly divided into the model group (SHR), the methylphenidate hydrochloride group (MPH, 4.22 mg/kg), and 3 LMQXM groups (low-dose (LD) group, 5.28 ml/kg; medium-dose (MD) group, 10.56 ml/kg; and high-dose (HD) group, 21.12 ml/kg), and administered by gavage for 4 weeks; the WKY rats were set as the control group. The open field test and Morris water maze test were used to evaluate the behavioral performance of rats, high performance liquid chromatography mass spectrometry (LC-MS) was used to analyze DA levels in the prefrontal cortex (PFC) and striatum of rats, ELISA was used to detect cAMP concentrations in the PFC and striatum, and immunohistochemistry and qPCR were used to analyze positive cell expression and mRNA expression for indicators related to DA and cAMP pathways.

Results: The results showed that beta-sitosterol, stigmasterol, rhynchophylline, baicalein, and formononetin might be key components of LMQXM for ADHD and that these components bind well to the core targets, DA receptors (DRD1 and DRD2). Furthermore, LMQXM might act through the DA and cAMP signaling pathways. In the animal experiment, we found that MPH and LMQXM-MD controlled hyperactivity and improved learning and memory in SHRs, while LMQXM-HD only controlled hyperactivity in SHRs; meanwhile, MPH and LMQXM-MD upregulated DA and cAMP levels, mean optical density (MOD) of cAMP, and MOD and mRNA expression of DRD1 and PKA in the prefrontal cortex (PFC) and striatum of SHRs, while LMQXM-LD and LMQXM-HD upregulated DA and cAMP levels in the striatum, MOD of cAMP in the PFC, and mRNA expression of PKA in the PFC. However, we did not find a significant regulatory effect of LMQXM on DRD2.

Conclusion: To sum up, this study demonstrated that LMQXM may increase DA levels mainly by activating the cAMP/PKA signaling pathway through DRD1, thereby controlling the behavioral disorders of SHRs, which is most effective at moderate doses, and this may be a key mechanism for LMQXM in the treatment of ADHD.

DSS-induced acute colitis causes dysregulated tryptophan metabolism in brain: an involvement of gut microbiota

Inflammatory bowel disease can cause pathological changes of certain organs, including the gut and brain. As the major degradation route of tryptophan (Trp), Kynurenine (Kyn) pathway are involved in multiple pathologies of brain. This study sought to explore the effects of Dextran sulphate sodium (DSS)-induced colitis on serum and brain Trp metabolism (especially the Kyn pathway) and its mechanisms. We induced acute colitis and sub-chronic colitis with 3% DSS and 1% DSS respectively and found more severe intestinal symptoms in acute colitis than sub-chronic colitis. Both of the colitis groups altered Trp-Kyn-Kynurenic acid (Kyna) pathway in serum by regulating the expression of rate-limiting enzyme (IDO-1, KAT2). Interestingly, only 3% DSS group activated Trp-Kyn pathway under the action of metabolic enzymes (IDO-1, TDO-2 and KAT2) in brain. Furthermore, intestinal flora 16S rRNA sequencing showed significantly changes in both DSS-induced colitis groups, including microbial diversity, indicator species, and the abundance of intestinal microflora related to Trp metabolism. The functional pathways of microbiomes involved in inflammation and Trp biosynthesis were elevated after DSS treatment. Moreover, correlation analysis showed a significant association between intestinal flora and Trp metabolism (both in serum and brain). In conclusion, our study suggests that DSS-induced acute colitis causes dysregulation of Trp-Kyn-Kyna pathways of Trp metabolism in serum and brain by affecting rate-limiting enzymes and intestinal flora.

DSS-induced colitis activates the kynurenine pathway in serum and brain by affecting IDO-1 and gut microbiota

Accumulative studies suggest that inflammatory bowel disease (IBD) may cause multiple central nervous system (CNS) pathologies. Studies have found that indoleamine-2,3-dioxygenase (IDO, rate-limiting enzyme of the kynurenine (Kyn) pathway) deficient mice were protected from endotoxin induced cognitive impairment, and Kyn administration induced cognitive memory deficits in both control and IDO-deficient mice. However, there is no investigation of the brain Kyn pathway in IBD, thus we investigated whether dextran sulfate sodium (DSS)-induced colitis could cause dysregulation of Kyn pathway in brain, and also in serum. C57BL/6J mice were given drinking water with 2% DSS for 10 consecutive days to induce colitis. In serum, we found significant increase in Kyn and kynurenic acid (Kyna) level, which was regulated by IDO-1 and KAT2 (rate-limiting enzymes of Trp-Kyn-Kyna pathway). Similarly, by analyzing GEO datasets, higher IDO-1 levels in peripheral blood monocytes and colon of UC patients was found. Furthermore, the Kyn pathway was significantly upregulated in the cerebral cortex under the action of IDO-1 after DSS treatment, which ultimately induced the neurotoxic phenotype of astrocytes. To investigate whether gut microbiota is involved in IBD-induced Kyn pathway dysregulation, we performed intestinal flora 16S rRNA sequencing and found that DSS-induced colitis significantly altered the composition and diversity of the gut microbiota. Metabolic function analysis also showed that Tryptophan metabolism, NOD-like receptor signaling pathway and MAPK signaling pathway were significantly up-regulated in the 2% DSS group. A significant association between intestinal flora and Trp metabolism (both in serum and brain) was found by correlation analysis. Overall, this study revealed that DSS-induced colitis causes dysregulation of the Kyn pathway in serum and brain by affecting rate-limiting enzymes and intestinal flora.

Study on the mechanism of acute liver injury protection in Rhubarb anthraquinone by metabolomics based on UPLC-Q-TOF-MS

As a traditional Chinese medicine, rhubarb has been used in a variety of liver diseases and it is widely used in clinic to prevent and treat acute liver injury. Anthraquinone, as the main medicinal component of rhubarb, can reverse the further development of liver fibrosis caused by acute liver injury. In this study, metabonomics was used to explore the mechanism of different doses of rhubarb anthraquinone on acute liver injury in rats. Rhubarb anthraquinone was administered intragastric to rats at doses of 3.9, 7.8 and 15.6 mg/kg, respectively, for 7 days, and then 30% CCl₄ was injected intraperitoneally at the dose of 1 ml/kg to replicate the acute liver injury model. The biochemical indicators content of ALT, AST, ALP, γ-GT, TG, TC, LDL, HDL in serum and GSH, Hyp, SOD, TNF-α, IL-6 and IL-8 in liver tissue extract were tested respectively, and liver tissue was histopathologically analysis. At the same time, UPLC-Q-TOF-MS combined with non-targeted metabolomics were used to study the metabolites and metabolic pathways of rhubarb anthraquinone in treating acute liver injury. Compared with normal rats, the contents of ALT, AST, ALP, TG, TC, LDL, γ-GT in serum and Hyp, MDA, IL-6, IL-8, TNF-α in the liver tissue extract were significantly increased in model rats (p < 0.05, p < 0.01), and the content of HDL in the serum was significantly decreased (p < 0.05); the activities of GSH and SOD in liver tissue extract were also significantly decreased (p < 0.05). After administration of rhubarb anthraquinone, compared with the model group, with the increase of dosage, some biochemical indexes showed opposite changes, and gradually approached to normal rats. 12 different metabolites were identified by metabonomics, and the biosynthesis and metabolism of phenylalanine, tyrosine and tryptophan, the metabolism of amino sugars, nucleotide sugars and pyrimidines metabolism, and the biosynthesis of steroid hormone were identified based on the biomarker analysis. Based on the biochemical analysis and metabonomics analysis of rats with acute liver injury treated with different doses of rhubarb anthraquinone, combined with histopathological observation, the results show that the protective effect of rhubarb anthraquinone on acute liver injury is related to the dosage; Meanwhile, the metabolic pathway analysis suggested that rhubarb anthraquinone alleviate acute liver injury by regulating inflammation, oxidative stress and fibrosis disorders. This study explained the therapeutic effect of rhubarb anthraquinone on acute liver injury from both material basis and action pathway, and provided safe and effective research ideas for clinical application of rhubarb.

Fresh Gastrodia elata Blume alleviates simulated weightlessness-induced cognitive impairment by regulating inflammatory and apoptosis-related pathways

In aerospace medicine, the influence of microgravity on cognition has always been a risk factor threatening astronauts' health. The traditional medicinal plant and food material Gastrodia elata Blume has been used as a therapeutic drug for neurological diseases for a long time due to its unique neuroprotective effect. To study the effect of fresh Gastrodia elata Blume (FG) on cognitive impairment caused by microgravity, hindlimb unloading (HU) was used to stimulate weightlessness in mice. The fresh Gastrodia elata Blume (0.5 g/kg or 1.0 g/kg) was intragastrically administered daily to mice exposed to HU and behavioral tests were conducted after four weeks to detect the cognitive status of animals. The behavioral tests results showed that fresh Gastrodia elata Blume therapy significantly improved the performance of mice in the object location recognition test, Step-Down test, and Morris Water Maze test, including short-term and long-term spatial memory. According to the biochemical test results, fresh Gastrodia elata Blume administration not only reduced serum factor levels of oxidative stress but also maintained the balance of pro-inflammatory and anti-inflammatory factors in the hippocampus, reversing the abnormal increase of NLRP3 and NF-κB. The apoptosis-related proteins were downregulated which may be related to the activation of the PI3K/AKT/mTOR pathway by fresh Gastrodia elata Blume therapy, and the abnormal changes of synapse-related protein and glutamate neurotransmitter were corrected. These results identify the improvement effect of fresh Gastrodia elata Blume as a new application form of Gastrodia elata Blume on cognitive impairment caused by simulated weightlessness and advance our understanding of the mechanism of fresh Gastrodia elata Blume on the neuroprotective effect.

Protective effect of compatible herbs in Jin-Gu-Lian formula against Alangium chinense-induced neurotoxicity via oxidative stress, neurotransmitter metabolisms, and pharmacokinetics

Background: A. chinense frequently used in Miao medicine to treat rheumatic diseases. However, as a famous toxic herb, Alangium chinense and its representative components exhibit ineluctable neurotoxicity, thus creating significant challenges for clinical application. The combined application with compatible herbs in Jin-Gu-Lian formula attenuates such neurotoxicity according to the compatible principle of traditional Chinese medicines. Purpose: We aimed to investigate the detoxification of the compatible herbs in Jin-Gu-Lian formula on A. chinense-induced neurotoxicity and investigate its mechanism. Methods: Neurobehavioral and pathohistological analysis were used to determine the neurotoxicity in rats administered with A. chinense extract (AC), extract of compatible herbs in Jin-Gu-Lian formula (CH) and combination of AC with CH for 14 days. The mechanism underlying the reduction of toxicity by combination with CH was assessed by enzyme-linked immunosorbent assays, spectrophotometric assays, liquid chromatography tandem-mass spectrometry and real-time reverse transcription-quantitative polymerase chain reaction. Results: Compatible herbs attenuated the AC-induced neurotoxicity as evidenced by increased locomotor activity, enhanced grip strength, the decreased frequency of AC-induced morphological damage in neurons, as well as a reduction of neuron-specific enolase (NSE) and neurofilament light chain (NEFL) levels. The combination of AC and CH ameliorated AC-induced oxidative damage by modulating the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC). AC treatment significantly reduced the levels of monoamine and acetylcholine neurotransmitters in the brains of rats, including acetylcholine (Ach), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), norepinephrine (NE), and serotonin (5-HT). Combined AC and CH treatment regulated the abnormal concentrations and metabolisms of neurotransmitters. Pharmacokinetic studies showed that the co-administration of AC and CH significantly decreased plasma exposure levels of two main components of AC, as evidenced by the reduction of maximum plasma concentration (C_max), area under the plasma concentration-time curve (AUC) compared to AC. In addition, the AC-induced downregulation in mRNA expression of cytochrome P450 enzymes was significantly reduced in response to combined AC and CH treatment. Conclusion: Compatible herbs in Jin-Gu-Lian formula alleviated the neurotoxicity induced by A. chinense by ameliorating oxidative damage, preventing abnormality of neurotransmitters and modulating pharmacokinetics.

Carrot-based fermentation juice rich in sleep-promoting components improved sleep in mice

The impact of fermentation by Levilactobacillus brevis YSJ3 on sleep-promoting components (SPCs) of carrot juice was evaluated. The contents of acetic acid, isovaleric acid, butyric acid, and γ-aminobutyric acid (GABA) significantly increased after fermentation. The beneficial effects of fermented carrot juice (FCJ) on sleep were evaluated in animal experiments. Behavioral test reveal SPCs-enriched FCJ could effectively relieve anxiety. The sleep duration in the FCJ group were extended compared to the control (NC) group and the unfermented carrot juice (UCJ) group. Moreover, the relative abundances of Ruminiclostridium and Akkermansia in the FCJ group and PC group, respectively, increased significantly, compared to the NC group the UCJ group. The contents of gut short-chain fatty acids in the FCJ group were significantly higher than that in the NC group and the UCJ group. The levels of GABA and 5-hydroxytryptamine in the brain for the FCJ group also increased significantly, compared to the NC group and the UCJ group. It indicated that SPCs-enriched FCJ effectively improved sleep in mice, which might be related to the fermentation of carrot juice and the compounds produced during the fermentation.

Disturbance of neurotransmitter metabolism in drug-naïve, first-episode major depressive disorder: a comparative study on adult and adolescent cohorts

Neurotransmitter metabolism plays a critical role in the pathophysiology of major depressive disorder (MDD). However, whether the neurotransmitter metabolism in adolescent MDD is differentiated from adult MDD is still elusive. In the current study, plasma concentrations of monoamine and amino acid neurotransmitters as well as their metabolites, including tryptophan (TRP), kynurenine (KYN), kynurenic acid (KYNA), serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), norepinephrine (NE), vanillylmandelic acid (VMA), 3-methoxy-4-hydroxyphenylglycol (MHPG), glutamine (GLN), glutamate (GLU) and gamma-aminobutyric acid (GABA), were measured and compared in two cohorts of subjects (adult cohort: 31 first-episode MDD vs. 35 healthy controls; adolescent cohort: 33 first-episode MDD vs. 30 healthy controls). To assess the effects of antidepressant treatment, we also analyzed the concentrations of these indexes pre- and post-treatment in adult and adolescent cohorts. At baseline, the deficits of neurotransmitter metabolism in adult MDD were manifested in all the neurotransmitter systems. In contrast, for adolescent MDD, the dysregulation of neurotransmission was mainly indicated in the catecholaminergic systems. After antidepressant treatment, adult MDD showed increased TRP, KYN, KYNA and GLU levels, together with decreased levels of 5-HIAA and DOPAC. Adolescent MDD illustrated an increased level of 5-HT and decreased levels of TRP and GABA. The improvements of Hamilton total scores correlated with the changes in plasma TRP and the turnover of KYN/TRP after treatment in all MDD patients. However, these correlations were only manifested in the adult MDD rather than in adolescent MDD patients. The findings highlight the shared and distinguished neurotransmitter pathways in MDD and emphasize the different antidepressant responses between adults and adolescents. Potentially, the neurotransmitters above could serve as diagnostic biomarkers and provide a novel pharmacological treatment strategy for MDD.

Gut microbiota-derived metabolites in inflammatory diseases based on targeted metabolomics

The gut microbiota plays an important role in inflammatory diseases. Metabolites in the three metabolic pathways of tryptophan (Trp), histidine (His), and phenylalanine (Phe) can affect various inflammatory conditions, such as obesity, diabetes, arthritis, colitis, atherosclerosis, and neuroinflammation. We established an LC–MS/MS method to measure 17 metabolites—Trp, 3-indole-acetic acid (Iaa), 3-indole-lactate (Ila), 3-indole-propionic acid (Ipa), 3-indole formaldehyde (Iald), kynurenine (Kn), kynurenic acid (Kyna), 3-Hydroxyanthranilic acid (3-Haa), His, 3-methylhistidine (3-Mhis), histamine (Hist), imidazole propionic acid (Imp), 4-imidazoacetic acid (Imaa), urocanic acid (Ua), Phe, phenylethylamine (Pea), and hippuric acid (Ha)—in the three metabolic pathways. The method exhibited high sensitivity and good selectivity, linearity, accuracy, precision, stability; and recovery rate; all met the requirements of biological sample analysis. By establishing a rheumatoid arthritis (RA) model of Sprague–Dawley rats and performing 16S rRNA sequencing on their feces, it was found that there was dysbiosis, including changes in phylum level, genus level, and α biodiversity of gut bacteria. The contents of the microbiota metabolites Iaa and Ipa in the model group were significantly decreased, and those of Iald, Kn, Kyna, Ha, and Imp were significantly increased. The common therapeutic drugs Tripterygium glycosides, total glucosides of peony, and their main active ingredients were screened by in vitro incubation with gut bacteria: it was found that Tripterygium glycosides and their active ingredients could lead to a variation in metabolites in the Trp and Phe pathways. Total glucosides and active components of peony could lead to a variation in metabolites in the Phe pathway of the gut microbiota.

Transcriptome and Metabolome Analysis Reveals the Importance of Amino-Acid Metabolism in Spodoptera Frugiperda Exposed to Spinetoram

Pests are inevitably exposed to sublethal and lethal doses in the agroecosystem following the application of pesticides indispensable to protect food sources. The effect of spinetoram on amino-acid metabolism of fall armyworm, Spodoptera frugiperda (J.E. Smith), was investigated, at the dose of LC₁₀ and LC₉₀, by transcriptome and LC-MS/MS analysis. Using statistics-based analysis of both POS and NEG mode, a total of 715,501 metabolites in S. frugiperda were significantly changed after spinetoram treatment. The enhancement of glucose metabolism provides energy support for detoxification in larvae. The decrease in valine and isoleucine is associated with an increase in leucine, without maintaining the conservation of citric acid in the larvae. The down-regulation of phenylalanine may retard the tricarboxylic acid cycle to produce GTP. The abundance of lysine was decreased in response to spinetoram exposure, which damages the nervous system of the larvae. The abundance of arginine increases and causes non-functional contraction of the insect's muscles, causing the larva to expend excess energy. Tryptophan provides an important substrate for eliminating ROS. The changes in glutamic acid, aspartic acid, and lysine cause damage to the nerve centers of the larvae. The results of transcriptome and LC-MS/MS analysis revealed the effects of pesticide exposure on amino-acid metabolism of S. frugiperda successfully and provide a new overview of the response of insect physio-biochemistry against pesticides.

Whole genome sequence analysis of two subspecies of Companilactobacillus Futsaii and experimental verification of drug resistance and effect on the exploratory behavior of mice based on unique gene

This study characterized the whole genome of Companilactobacillus futsaii subsp. chongqingii CQ16Z1 isolated from Chongqing of China, performed genome sequence analysis with Companilactobacillus futsaii subsp. futsaii YM0097 isolated from Taiwan of China, and experimentally verified drug resistance and effect on the exploratory behavior of male C57BL/6 mice and analysis of gut microbiota and metabolomic studies. The genome of CQ16Z1 is 2.6 Mb. Sequence analysis between genomes showed that the two strains are Companilactobacillus futsaii. The unique genes of CQ16Z1 and YM0097 are 217 and 267, which account for 9% and 11% of the whole genomes, respectively. According to unique gene annotation, the results showed that genes associated with carbohydrate metabolism, environmental information processing, metabolism of cofactors and vitamins, cell wall/membrane/envelope biogenesis, phage and drug resistance are significantly different. The results of the drug resistance experiment showed that YM0097 had different degrees of resistance to 13 antibiotics, while CQ16Z1 was sensitive to more than half of them. YM0097 contains 9 prophage regions and CQ16Z1 contains 3 prophage regions. The results of the open field test showed that the time (P = 0.005; P = 0.047) and distance (P < 0.010; P = 0.046) of the central area of Y97 group and CQ group are significantly different from the control group. The results of the elevated plus maze test showed that compared with the control group, Y97 group had significant differences in the number of entries to the open arms and the percentage of open arms entry times (P = 0.004; P = 0.025), while the difference between the CQ group and the control group was not significant. YM0097 has a more obvious effect on the exploratory behavior of mice. The effects of YM0097 and CQ16Z1 on the intestinal flora of mice are also different. YM0097 may be more beneficial to the intestinal flora of the host. And LC/MS also showed that the metabolic effects of the two strains on the host are different. Finally, we believe that YM0097 is more suitable for application research as a psychobiotics.

Effects of Changyu Daotan Decoction on Depression via Restoration of Mice Hippocampus and Alteration of Expression of Relevant Neurotrophic Factors

Depression, a sort of common psychological disorder, is a serious hazard to people’s health and social progress. Conventional clinical means for this disorder nowadays are mostly chemical medicine treatments accompanied by psychological counseling. Chinese application of using TCM to treat mental diseases like depression could be traced from hundreds of years ago, in comparison to the long-term depression course and the chemical medicine administration demerits like side effects and resistance, traditional Chinese medicines are milder, more lasting, stable and are the optimal choice for perennial depression treatment. This study was committed to making a comprehensive investigation of Changyu Daotan Decoction’s efficacy in the depression mice model, and it turned out that the Changyu Daotan Decoction was capable of restoring the hippocampus of the depression mice and altering the expressions of neurotrophic factors (the expressions of β-Catenin, cyclin D1 and in GSK-3β BDNF, GFAP, NGF, and Wnt signaling pathways). Results of metabonomics analysis showed that the contents of GABA, His, Tyr, Trp, PA, and 5-HIAA in the mice of the Changyu Daotan Decoction group were restored after administration and showed a conspicuous relevance with the metabolic.

Effect of Radix Polygalae extract on the colonic dysfunction in rats induced by chronic restraint stress

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Polygalae, a commonly used traditional Chinese herb, has conventionally functioned in tranquilization and sedation, where anti-inflammation may be the underlying mechanism.

AIM OF THE STUDY

Chronic restraint stress (CRS), a risk factor for the etiology of intestinal disorders, was used in the present study to examine whether Radix Polygalae extract (RPE) could modulate colonic dysfunction in CRS rats.

MATERIALS AND METHODS

Wistar rats were exposed to 28-day CRS (6 h daily), and RPE (135 mg/kg and 270 mg/kg) was intragastrically administered 1 h before CRS. Subsequently, the gut microbiota was determined using metagenomic sequencing. Colonic proinflammatory interleukin-1β, -6, and -18 were assayed using qRT-PCR and ELISA. Tight junction proteins were quantified by qRT-PCR and western blotting (WB), and tryptophan metabolic enzymes and metabolites were determined using qRT-PCR and UFLC-QTRAP-5500/MS. Moreover, protein expression of colonic tight junction proteins, NF-κB-NLRP3 signaling involved in the underlying mechanism of RPE were detected by WB.

RESULTS

RPE significantly decreased proinflammatory cytokines and reshaped the gut microbiota, especially the probiotics, including Lactobacillus and Bacteroides. Moreover, RPE could modulate the metabolite contents and enzyme expression associated with colonic tryptophan-kynurenine (TRP-KYN) metabolism and could increase tight junction protein expression in CRS rats. Furthermore, RPE inhibited the activation of NF-κB-NLRP3 signaling in the colon of CRS rats.

CONCLUSION

RPE could modulate colonic inflammation, colonic microbiota, tight junction, TRP-KYN metabolism and NF-κB-NLRP3 signaling to reach a colonic balance of CRS rats. The present study helped us to better understand and appreciate the various beneficial effects of RPE.

The modulatory effect of 100 Hz electroacupuncture on striatal synaptic plasticity in unilateral lesioned 6-OHDA rats

Recent studied have reported that impaired striatal synaptic plasticity played a crucial role in Parkinson's disease (PD). Previous studies have suggested that electroacupuncture (EA) alleviated the motor deficits in PD patients and animal models. However, the mechanisms underlying this protection need to be further elucidated. In this study, we found that EA-induced improvement of motor deficits in the 6-hydroxydopamine (6-OHDA) rat model doesn't act through dopaminergic system. EA rescued the decreased striatal long-term potentiation (LTP) in 6-OHDA rats. In addition, the declined expression of N-methyl-D-aspartic acid receptor subunit 2B (NR2B) in the striatum was remarkably up-regulated by EA. The EA-induced improvement of LTP can be eliminated by NR2B-selective inhibitor. It is indicated that EA-induced recovery of striatal LTP was correlated with the up-regulation of NR2B subunit. EA was also found to rescue the decreased dendritic arborization and the spine density in the striatum of 6-OHDA rats. Meanwhile, EA suppressed striatal glutamate content and vesicular glutamate transporter 1 which is expressed in cortico-striatal glutamatergic projections. The decrease of striatal glutamate content induced by decortication, EA treatment or a combination of both reversed the loss of striatal spine density in 6-OHDA rats. It is indicated that EA-induced reduction of cortico-striatal glutamate transmission contributes to the recovery of striatal spine density. In conclusion, the therapeutic effect of EA on the motor deficits of 6-OHDA rats was mediated by rescuing cortico-striatal glutamate transmission and striatal synaptic plasticity.

Water Extract of Ecklonia cava Protects against Fine Dust (PM2.5)-Induced Health Damage by Regulating Gut Health

To confirm the therapeutic effect of the water extract from Ecklonia cava (WEE) against PM_2.5 induced systemic health damage, we evaluated gut health with a focus on the microbiota and metabolites. Systemic damage in mice was induced through PM_2.5 exposure for 12 weeks in a whole-body chamber. After exposure for 12 weeks, body weight and food intake decreased, and WEE at 200 mg/kg body weight (mpk) alleviated these metabolic efficiency changes. In addition, PM_2.5 induced changes in the length of the colon and fecal water content. The administration of the WEE at 200 mpk oral dose effectively reduced changes in the colon caused by PM_2.5 exposure. We also attempted to confirm whether the effect of the WEE is mediated via regulation of the microbiota-gut-brain axis in mice with PM_2.5 induced systemic damage. We examined changes in the fecal microbiota and gut metabolites such as short-chain fatty acids (SCFAs) and kynurenine metabolites. In the PM_2.5 exposed group, a decrease in the abundance of Lactobacillus (Family: Lactobacillaceae) and an increase in the abundance of Alistipes (Family: Rikenellaceae) were observed, and the administration of the WEE showed a beneficial effect on the gut microbiota. In addition, the WEE effectively increased the levels of SCFAs (acetate, propionate, and butyrate). Furthermore, kynurenic acid (KYNA), which is a critical neuroprotective metabolite in the gut-brain axis, was increased by the administration of the WEE. Our findings suggest that the WEE could be used as a potential therapeutic against PM_2.5 induced health damage by regulating gut function.

The qualitative and quantitative profiling for quality assessment of Yinxing Mihuan Oral Solution and the stability study on the focused flavonol glycosides

Yinxing Mihuan Oral Solution (YMOS) has been widely applied for the treatment of coronary heart disease, angina pectoris, and cerebral ischemic disease in clinical practice. Nonetheless, the limited basic researches on quality analysis of YMOS remain a critical bottleneck that needs to be enhanced for better clinical applications. In this study, a total of 67 chemical components, including flavonoids, terpene lactones, nucleosides, etc., were tentatively characterized by ultra-high performance liquid chromatography tandem Q-Exactive Orbitrap high-resolution mass spectrometry, among which 34 compounds were further identified by comparison with reference substances. By adopting a methodologically validated method, we discovered that the quantitative estimate of multi-compounds in 22 batches of YMOS showed lot-to-lot consistency, and the additives in YMOS also met the corresponding regulations. Furthermore, five flavonol glycosides whose content presented a downward trend in the expired YMOS were focused. A systematic research on stability test focusing on the five targeted flavonol glycosides was performed under different temperatures and pH levels. It was found that ortho-diphenolic hydroxyl group on B-ring and the type of saccharide connected to 3-hydroxyl on C-ring play a pivotal role in the stability of the tested compounds. Subsequently, as the important compounds, ginkgolides A, B, and C in YMOS were simultaneously quantified with ultra performance liquid chromatography coupled with triple quadrupole mass spectrometry. In brief, this study performs a reliable chemical identification and provides a rapid and feasible method for the quality evaluation, which contributes to the in-depth investigation and safe application of YMOS for clinical uses.

Glutamine and norepinephrine in follicular fluid synergistically enhance the antioxidant capacity of human granulosa cells and the outcome of IVF-ET

An increasing number of studies demonstrate that changes in neurotransmitters metabolic levels in follicular fluid are directly related to oocyte maturation, fertilization, the quality of embryo and pregnancy rates. However, the relationship between the intra-follicular neurotransmitters and the function of granulosa cells (GCs), and the outcome of in vitro fertilization-embryo transfer (IVF-ET) is not clear. Human follicular fluid and cumulus GCs were harvested from large follicles obtained from patients undergoing IVF. Neurotransmitters and steroid hormones in follicular fluid were measured through liquid chromatography-tandem mass spectrometry (LC-MS/MS) and high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS). Based on the content of glutamine (Gln) in follicular fluid, the samples were divided into two groups: high Gln level group and low Gln level group. The expression of proliferation-, steroidogenesis- and antioxidant-related genes in GCs was detected by qRT-PCR. In vitro, KGN cells were used to further verify the effects of Gln and NE on GCs function. Primary and secondary outcomes were the number of mature and retrieved oocytes, and the ratio of high-quality embryos, respectively. Gln (46.75 ± 7.74 μg/mL) and norepinephrine (NE, 0.20 ± 0.07 μg/mL) were abundant neurotransmitters in follicular fluid, and exhibited a significantly positive correlation (R = 0.5869, P < 0.005). In high Gln level group, the expression of proliferation, steroidogenesis and antioxidant-related genes in GCs were higher than those in low Gln level group, and the contents of estriol and E2 in follicular fluid were more abundant. Moreover, the concentrations of Gln and NE in follicular fluid showed significantly positive correlation with IDH1 expression in GCs (R = 0.3822, R = 0.4009, P < 0.05). Importantly, a significantly positive correlation was observed between IDH1 expression in GCs and the ratio of higher-quality/cleaved embryos (R = 0.4480, P < 0.05). In vitro studies further demonstrated that Gln and NE played synergistically function in improving GCs proliferation and E2 production by upregulating IDH1 expression. These data demonstrate that Gln and NE in follicular fluid might play significant positive roles in GCs function, and may be potential predictors for selecting optimal quality oocytes and evaluating the quality of embryonic development.

Quantitative analysis of 20 purine and pyrimidine metabolites by HILIC-MS/MS in the serum and hippocampus of depressed mice

Purine and pyrimidine metabolism are vital metabolic pathways in the development, proliferation or repairment of cells or tissues associated with various diseases. Here, a simple, all-in-one injection hydrophilic interaction liquid chromatography-tandem mass spectrometry method was developed for simultaneous determination of 20 metabolites: adenine, adenosine, deoxyadenosine, adenosine 5'-monophosphate, cyclic adenosine monophosphate, hypoxanthine, xanthine, inosine, deoxyinosine, xanthosine, xanthosine 5'-monophosphate and uric acid, which are products of purine metabolism; uridine, deoxyuridine, uridine 5'-monophosphate and uracil, are products of pyrimidine metabolism; and corticosterone, methionine, acetylcholine and serotonin. To minimize interference of endogenous molecules in sample matrixes, a combination of activated carbon adsorption and a serum substitute matrix (5% bovine serum albumin in phosphate buffered saline) was utilized and jointly applied. The sensitivity, linearity, stability, precision, accuracy and extraction recovery were evaluated, and the method was demonstrated to be accurate, sensitive and reliable. An analytical strategy was successfully applied to quantitatively determine 20 metabolite levels in the serum and hippocampus of mice with chronic social defeat stress-induced depression. The results showed greatly perturbed purine metabolism in the depressed mice, which was primarily characterized by dramatic increases in hypoxanthine, xanthine and inosine in serum and reduced levels of adenine, adenosine and adenosine 5'-monophosphate in the hippocampus. These findings suggest that this novel strategy can facilitate the quantitative analysis of adenine and other purine and pyrimidine metabolites in tissue and serum and exhibits great potential in the exploration of metabolism-related mechanisms of relevant diseases.

Bifidobacterium longum CCFM1077 Ameliorated Neurotransmitter Disorder and Neuroinflammation Closely Linked to Regulation in the Kynurenine Pathway of Autistic-like Rats

The kynurenine pathway (KP) is abnormal in autistic patients and model animals. According to studies on the brain–gut axis, probiotics can help ameliorate the metabolic abnormalities of the KP in patients and model animals with neurological diseases. This study was aimed at evaluating the ability of Bifidobacterium longum (B. longum) CCFM077 to enhance the gut microbiome and KP metabolism and regulate the neurotransmitter levels and neuroinflammation of autistic rats. The KP metabolism of autistic rats was significantly disordered and significantly related to the regulation of neurotransmitter (excitation and inhibition) and neuroglia states. B. longum CCFM1077 could effectively alleviate autistic-like behaviours (repetitive stereotyped behaviour, learning and memory ability, and despair mood) and regulate the KP metabolism in the periphery system (gut and blood) and brain. In particular, B. longum CCFM1077 could significant regulate the quinolinic acid (QUIN) level in the brain and markedly regulate glutamic acid (Glu) and Glu/γ-aminobutyric acid (GABA) levels in the brain while alleviating microglia activity in the cerebellum. Through a correlation analysis, the QUIN level in the brain was strongly related with autistic-like behaviours and neurotransmitter levels (GABA and Glu). The QUIN level may thus be a potential therapeutic marker for treating autism through the intestinal and neural pathways.

Amino acids in inflammatory bowel diseases: Modern diagnostic tools and methodologies

Amino acids are crucial building blocks of living organisms. Together with their derivatives, they participate in many intracellular processes to act as hormones, neuromodulators, and neurotransmitters. For several decades amino acids have been studied for their potential as markers of various diseases, including inflammatory bowel diseases. Subsequent improvements in sample pretreatment, separation, and detection methods have enabled the specific and very sensitive determination of these molecules in multicomponent matrices-biological fluids and tissues. The information obtained from targeted amino acid analysis (biomarker-based analytical strategy) can be further used for early diagnostics, to monitor the course of the disease or compliance of the patients. This review will provide an insight into current knowledge about inflammatory bowel diseases, the role of proteinogenic amino acids in intestinal inflammation and modern analytical techniques used in its diagnosis and disease activity monitoring. Current advances in the analysis of amino acids focused on sample pretreatment, separation strategy, or detection methods are highlighted, and their potential in clinical laboratories is discussed. In addition, the latest clinical data obtained from the metabolomic profiling of patients suffering from inflammatory bowel diseases are summarized with a focus on proteinogenic amino acids.

Self-Fluorescent Lone Tryptophan Nanoparticles as Theranostic Agents Against Alzheimer's Disease

Aggregation of β-amyloid (Aβ42) peptide in the neural extracellular space leads to cellular dysfunction, resulting in Alzheimer's disease (AD). The hydrophobic core of the amyloidogenic Aβ42 peptide contains aromatic residues that play an important role in the self-assembly and subsequent aggregation of the peptide. Hence, targeting these hydrophobic core residues by potent low molecular agents can be a promising therapeutic approach toward AD. In the current work, we have developed self-fluorescent solo tryptophan nanoparticles (TNPs) as nanotheranostic systems against AD. We demonstrated that TNPs could significantly inhibit as well as disrupt the fibrils formed by both Aβ42 peptide and another reductionist approach-based amyloid model dipeptide, phenylalanine-phenylalanine (FF). More importantly, these nanostructures were nontoxic to neural cells and could protect the neurons from Aβ42 peptide and FF aggregate-induced cytotoxicity. In addition, efficacy studies performed in animal model further revealed that the TNPs could rescue spatial and learning memory in intracerebroventricular streptozotocin-administration-induced AD phenotype in rats. Moreover, our pharmacokinetics study further established the BBB permeability and brain delivery potency of TNPs. The inherent excellent fluorescent properties of these nanoparticles could be exploited further to use them as imaging modalities for tagging and detecting FF and Aβ42 peptide fibrils. Overall, our results clearly illustrated that the solo TNPs could serve as promising nanotheranostic agents for AD therapy.

Kynurenine Pathway Metabolites as Potential Clinical Biomarkers in Coronary Artery Disease

Coronary artery disease (CAD) is one of the leading cause of mortality worldwide. Several risk factors including unhealthy lifestyle, genetic background, obesity, diabetes, hypercholesterolemia, hypertension, smoking, age, etc. contribute to the development of coronary atherosclerosis and subsequent coronary artery disease. Inflammation plays an important role in coronary artery disease development and progression. Pro-inflammatory signals promote the degradation of tryptophan via the kynurenine pathway resulting in the formation of several immunomodulatory metabolites. An unbalanced kynurenic pathway has been implicated in the pathomechanisms of various diseases including CAD. Significant improvements in detection methods in the last decades may allow simultaneous measurement of multiple metabolites of the kynurenine pathway and such a thorough analysis of the kynurenine pathway may be a valuable tool for risk stratification and determination of CAD prognosis. Nevertheless, imbalance in the activities of different branches of the kynurenine pathway may require careful interpretation. In this review, we aim to summarize clinical evidence supporting a possible use of kynurenine pathway metabolites as clinical biomarkers in various manifestations of CAD.

Protective effects of chlorogenic acid on trimethyltin chloride-induced neurobehavioral dysfunctions in mice relying on the gut microbiota

Trimethyltin chloride (TMT) is acknowledged to have potent neurotoxicity. Chlorogenic acid (CGA), the most abundant polyphenol in the human diet, is well-known for its neuroprotective activity. This investigation was performed to determine the effects and mechanisms of CGA on TMT-induced neurobehavioral dysfunctions. Mice received oral administrations of CGA (30 mg kg^-1) for 11 days, in which they were intraperitoneally injected with TMT (2.7 mg kg^-1) once on the 8th day. The daily intake of CGA significantly alleviated TMT-induced epilepsy-like seizure and cognition impairment, ameliorating hippocampal neuronal degeneration and neuroinflammation. Oral gavage of CGA potentially exerted neuroprotective effects through JNK/c-Jun and TLR4/NFκB pathways. Microbiome analysis revealed that daily consumption of CGA raised the relative abundance of Lactobacillus in TMT-treated mice. SCFAs, the gut microbial metabolites associated with neuroprotection, were increased in the mouse hippocampus following CGA treatment. TMT-induced neurotransmitter disorders were regulated by oral gavage of CGA, especially DL-kynurenine and acetylcholine chloride. Additionally, neurotransmitters in the mouse hippocampus were found to be highly associated with the gut microbiota. Our findings provided research evidence for the neuroprotective effect of CGA on TMT-induced neurobehavioral dysfunctions.

Maternal plasma serotonin level not suitable as postpartum depression diagnostic biomarker: Results from a prospective cohort study

BACKGROUND

Whether plasma serotonin (5-HT) levels could be a biomarker for postpartum depression (PPD) diagnosis is under dispute.

METHODS

A total of 979 of pregnant women without antenatal depression at the time of delivery (TD) were enrolled and followed up at six weeks postpartum (SWP) in Changsha, China. The odds ratio (OR) and 95% confidence interval (CI) for plasma 5-HT level at TD, at SWP, changes in 5-HT, and risk of PPD and deterioration in EPDS scores at SWP were estimated by Logistic regressions. Restricted cubic spline (RCS) functions were also used to assess the dose-response relationships.

RESULTS

The 6-week cumulative incidence of PPD was 12.05% (95%CI:10.08%, 14.26%). The average level of plasma 5-HT changed from 223.65 ± 131.47 ng/ml at TD to 216.43 ± 122.73 ng/ml at SWP, with an average change of -7.22 ± 96.54 ng/ml. Plasma 5-HT at TD was negatively correlated with EPDS score at TD and SWP (p < 0.05), as was the correlation between 5-HT at SWP and EPDS scores at SWP (p = 0.038). However, the changes in 5-HT were not associated with the EPDS score at SWP (p = 0.346). Neither plasma 5-HT level at TD nor changes in 5-HT was associated with PPD at SWP or deterioration in EPDS scores (p < 0.05). Plasma 5-HT at delivery had insignificant discriminatory power for diagnosing PPD and prediction of deterioration in EPDS scores (p ≥ 0.05).

CONCLUSION

Plasma 5-HT level at delivery was associated with EPDS score at delivery and SWP, but not with PPD at SWP suggesting that plasma 5-HT is not suitable as PPD diagnostic biomarker.

Targeted UHPLC-ESI-MS/MS Analysis of Selected Neurotransmitters, Tryptophan and Its Metabolite Kynurenine in Tau Transgenic Rat Brain Tissue: A Pivotal Study

Neurotransmitters (NT) are widely distributed in the central nervous system. These molecules are important for many physiological processes and the function of the immune system. Imbalance of NT are linked to numerous neurological disorders and diseases, including tauopathies. Here, a targeted approach based on on-line combination of ultra-high performance liquid chromatography with tandem mass spectrometry was validated and applied to the quantitative analysis of nine NT (acetylcholine, choline, aspartic acid, asparagine, glutamic acid, glutamine, pyroglutamate, γ-aminobutyric acid, N-acetyl-L-aspartic acid), tryptophan and its metabolite kynurenine in brain tissue samples of a rat model for tauopathy. The applied analytical method was characterized by excellent validation parameters for all analytes, such as limits of detection in the range of 0.01–1.70 µg/mL, regression coefficients of the calibration curves ≥ 0.9946, intra-day and inter-day precision expressed as coefficient of variation in the range of 0.6–11.9% and 0.6–14.4%, and accuracy in the range of 87.6–107.1% and 87.2–119.6%. Our analytical approach led to the identification of increased levels of choline and γ-aminobutyric acid in pons, and elevated concentration levels of pyroglutamate in medulla oblongata. These findings indicate that NT could play a valuable role in the study and clarification of neuroinflammation and neurodegenerative diseases.

Screening and identification of differential metabolites in serum and urine of bamaxiang pigs bitten by trimeresurus stejnegeri based on UPLC-Q-TOF/MS metabolomics technology

Trimeresurus stejnegeri is one of the top ten venomous snakes in China, and its bite causes acute and severe diseases. Elucidating the metabolic changes of the body caused by Trimeresurus stejnegeri bite will be beneficial to the diagnosis and treatment of snakebite. Thus, an animal pig model of Trimeresurus stejnegeri bite was established, and then the metabolites of serum and urine were subsequently screened and identified in both ESI+ and ESI- modes identified by ultra-performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS) methods. There are 9 differential metabolites in serum, including Oleic acid, Lithocholic acid, Deoxycholic acid, Hypoxanthine, etc. There are 11 differential metabolites in urine, including Dopamine, Thiocysteine, Arginine, Indoleacetaldehyde, etc. Serum enrichment pathway analysis showed that 5 metabolic pathways, including Tryptophanuria, Liver disease due to cystic fibrosis, Hartnup disease, Hyperbaric oxygen exposure and Biliary cirrhosis, the core metabolites in these pathways, including deoxycholic acid, lithocholic acid, tryptophan and hypoxanthine, changed significantly. Urine enrichment pathway analysis showed that 4 metabolic pathways, including Aromatic L-Amino Acid Decarboxylase, Vitiligo, Blue Diaper Syndrome and Hyperargininemia, the core metabolites in these pathways including dopamine, 5-hydroxyindole acetic acid and arginine. Taken together, the current study has successfully established an animal model of Trimeresurus stejnegeri bite, and identified the metabolic markers and metabolic pathways of Trimeresurus stejnegeri bite. These metabolites and pathways may have potential application value and provide a therapeutic basis for the treatment of Trimeresurus stejnegeri bite.

Metabolomics Analysis of the Prefrontal Cortex in a Rat Chronic Unpredictable Mild Stress Model of Depression

BACKGROUND

Depressive disorder is the leading cause of disability and suicidality worldwide. Metabolites are considered indicators and regulators of depression. However, the pathophysiology of the prefrontal cortex (PFC) in depression remains unclear.

METHODS

A chronic unpredictable mild stress (CUMS) model and a maturation rodent model of depression was used to investigate metabolic changes in the PFC. Eighteen male Sprague-Dawley rats were randomly divided into CUMS and control groups. The sucrose preference test (SPT) and forced swimming test (FST) were employed to evaluate and record depression-associated behaviors and changes in body weight (BW). High-performance liquid chromatography-tandem mass spectrometry was applied to test metabolites in rat PFC. Furthermore, principal component analysis and orthogonal partial least-squares discriminant analysis were employed to identify differentially abundant metabolites. Metabolic pathways were analyzed using MetaboAnalyst. Finally, a metabolite-protein interaction network was established to illustrate the function of differential metabolites.

RESULTS

SPT and FST results confirmed successful establishment of the CUMS-induced depression-like behavior model in rats. Five metabolites, including 1-methylnicotinamide, 3-methylhistidine, acetylcholine, glycerophospho-N-palmitoyl ethanolamine, α-D-mannose 1-phosphate, were identified as potential biomarkers of depression. Four pathways changed in the CUMS group. Metabolite-protein interaction analysis revealed that 10 pathways play roles in the metabolism of depression.

CONCLUSION

Five potential biomarkers were identified in the PFC and metabolite-protein interactions associated with metabolic pathophysiological processes were explored using the CUMS model. The results of this study will assist physicians and scientists in discovering potential diagnostic markers and novel therapeutic targets for depression.

Combining Metabolomics and Interpretable Machine Learning to Reveal Plasma Metabolic Profiling and Biological Correlates of Alcohol-Dependent Inpatients: What About Tryptophan Metabolism Regulation?

Alcohol dependence (AD) is a condition of alcohol use disorder in which the drinkers frequently develop emotional symptoms associated with a continuous alcohol intake. AD characterized by metabolic disturbances can be quantitatively analyzed by metabolomics to identify the alterations in metabolic pathways. This study aimed to: i) compare the plasma metabolic profiling between healthy and AD-diagnosed individuals to reveal the altered metabolic profiles in AD, and ii) identify potential biological correlates of alcohol-dependent inpatients based on metabolomics and interpretable machine learning. Plasma samples were obtained from healthy (n = 42) and AD-diagnosed individuals (n = 43). The plasma metabolic differences between them were investigated using liquid chromatography-tandem mass spectrometry (AB SCIEX^® QTRAP 4500 system) in different electrospray ionization modes with scheduled multiple reaction monitoring scans. In total, 59 and 52 compounds were semi-quantitatively measured in positive and negative ionization modes, respectively. In addition, 39 metabolites were identified as important variables to contribute to the classifications using an orthogonal partial least squares-discriminant analysis (OPLS-DA) (VIP > 1) and also significantly different between healthy and AD-diagnosed individuals using univariate analysis (p-value < 0.05 and false discovery rate < 0.05). Among the identified metabolites, indole-3-carboxylic acid, quinolinic acid, hydroxy-tryptophan, and serotonin were involved in the tryptophan metabolism along the indole, kynurenine, and serotonin pathways. Metabolic pathway analysis revealed significant changes or imbalances in alanine, aspartate, glutamate metabolism, which was possibly the main altered pathway related to AD. Tryptophan metabolism interactively influenced other metabolic pathways, such as nicotinate and nicotinamide metabolism. Furthermore, among the OPLS-DA-identified metabolites, normetanephrine and ascorbic acid were demonstrated as suitable biological correlates of AD inpatients from our model using an interpretable, supervised decision tree classifier algorithm. These findings indicate that the discriminatory metabolic profiles between healthy and AD-diagnosed individuals may benefit researchers in illustrating the underlying molecular mechanisms of AD. This study also highlights the approach of combining metabolomics and interpretable machine learning as a valuable tool to uncover potential biological correlates. Future studies should focus on the global analysis of the possible roles of these differential metabolites and disordered metabolic pathways in the pathophysiology of AD.

Electrochemical Determination of Kynurenine Pathway Metabolites-Challenges and Perspectives

In recent years, tryptophan metabolism via the kynurenine pathway has become one of the most active research areas thanks to its involvement in a variety of physiological processes, especially in conditions associated with immune dysfunction, central nervous system disorders, autoimmunity, infection, diabetes, and cancer. The kynurenine pathway generates several metabolites with immunosuppressive functions or neuroprotective, antioxidant, or toxic properties. An increasing body of work on this topic uncovers a need for reliable analytical methods to help identify and quantify tryptophan metabolites at physiological concentrations in biological samples of different origins. Recent methodological advances in the fabrication and application of electrochemical sensors promise a rise in the future generation of novel analytical systems. This work summarizes current knowledge and provides important suggestions with respect to direct electrochemical determinations of kynurenine pathway metabolites (kynurenines) in complex biological matrices. Measurement challenges, limitations, and future opportunities of electroanalytical methods to advance study of the implementation of kynurenines in disease conditions are discussed.

Baihe Jizihuang Tang Ameliorates Chronic Unpredictable Mild Stress-Induced Depression-Like Behavior: Integrating Network Pharmacology and Brain-Gut Axis Evaluation

Baihe Jizihuang Tang (BHT) is a traditional Chinese medicine (TCM) prescription, which can also be used as a nutritional food with medicinal value. Herein, we aimed to clarify the antidepressive effects and molecular mechanism of BHT. Network pharmacological analysis; chronic unpredictable mild stress (CUMS) rat model assessment; behavioral tests; analysis of hippocampal neurotransmitter levels, hippocampal pathological structure, and hypothalamic-pituitary-adrenal (HPA) axis; western blot analysis; 16s RNA sequencing; ultraperformance liquid chromatography (UPLC)/mass spectrometry (MS); and high-performance liquid chromatography (HPLC)/ultraviolet (UV) analysis were used. We found 8 potentially active components and 12 targets from the database. KEGG analysis suggested that BHT significantly affected BDNF/tyrosine receptor kinase B levels, glutamate binding, synaptic transmission based on neurotransmitter signal, and the response to glucocorticoid signaling pathways. Consistently, 7 chemical components were identified using UPLC/quadrupole time-of-flight/MS; among them, regalosides A, B, C, and E were unique components of lily of TCM, and their content in BHT was significantly different: regaloside A > B > E > C. BHT could nourish hippocampal neurons, affect neurotransmitter metabolism, reduce HPA axis hyperactivity, improve deficits in hippocampal tissue structure, and change depressive behavior. Moreover, BHT regulated BDNF expression in the hippocampus and improved intestinal flora deficits in CUMS rats by changing the content of Bifidobacterium, Rothia, Glutamicibacter, and Lactobacillus at the genus level. Collectively, BHT attenuated CUMS-induced depression-like behavior by regulating BDNF and intestinal flora disorder through the brain-gut axis. Therefore, including BHT in the medication list may constitute a potential strategy for preventing depression.