Association between arginine catabolism and major depressive disorder: A protocol for the systematic review and meta-analysis of metabolic pathway

Relationship between Urinary Metabolomic Profiles and Depressive Episode in Antarctica

Antarctic expeditions have a high risk of participant depression owing to long stays and isolated environments. By quantifying the stress state and changes in biomolecules over time before the onset of depressive symptoms, predictive markers of depression can be explored. Here, we evaluated the psychological changes in 30 participants in the Japanese Antarctic Research Expedition using the Patient Health Questionnaire-9 (PHQ-9). Urinary samples were collected every three months for a year, and comprehensive urinary metabolomic profiles were quantified using liquid chromatography time-of-flight mass spectrometry. Five participants showed major depressive episodes (PHQ-9 ≥ 10) at 12 months. The urinary metabolites between these participants and the 25 unaffected participants were compared at individual metabolite and pathway levels. The individual comparisons showed the most significant differences at 12 months in 14 metabolites, including ornithine and beta-alanine. Data from shorter stays showed less significant differences. In contrast, pathway and enrichment analyses showed the most significant difference at three months and a less significant difference at longer stays. These time transitions of urinary metabolites could help in the development of urinary biomarkers to detect subjects with depressive episodes at an early stage.

Tao-Hong-Si-Wu decoction improves depressive symptoms in model rats via amelioration of BDNF-CREB-arginase I axis disorders

CONTEXT

The traditional Chinese medicine formula Tao-Hong-Si-Wu decoction (TSD), used for treating ischaemic stroke, has the potential to treat depressive disorder (DD).

OBJECTIVE

To explore the effective targets of TSD on DD animal models.

MATERIALS AND METHODS

Sprague-Dawley (SD) rats were modelled by inducing chronic unpredictable mild stress (CUMS) during 35 days and treated with three dosages of TSD (2.5, 5 and 10 g/kg) or fluoxetine (10 mg/kg) by oral gavage for 14 days. Bodyweight measurements and behavioural tests were performed to observe the effect of TSD on the CUMS animals. A gas chromatography coupled with mass spectrometry (GC-MS)-based metabolomic analysis was conducted to reveal the metabolic characteristics related to the curative effect of TSD. Levels of the proteins associated with the feature metabolites were analysed.

RESULTS

Reduced immobile duration and crossed squares in the behavioural tests were raised by 48.6% and 32.9%, on average, respectively, by TSD treatment (ED₅₀=3.2 g/kg). Antidepressant effects of TSD were associated with 13 decreased metabolites and the restorations of ornithine and urea in the serum. TSD (5 g/kg) raised serum serotonin by 54.1 mg/dL but suppressed arginase I (Arg I) by 47.8 mg/dL in the CUMS rats. Proteins on the brain-derived neurotrophic factor (BDNF)-cAMP response element-binding protein (CREB) axis that modulate the inhibition of Arg I were suppressed in the CUMS rats but reversed by the TSD intervention.

DISCUSSION AND CONCLUSIONS

TSD improves depression-like symptoms in CUMS rats. Further study will focus on the antidepressant-like effects of effective compounds contained in TSD.

Ketamine alleviating depressive-like behaviors is associated with regulation of nNOS–CAPON–Dexras1 complex in chronic unpredictable mild stress rats

Background

A growing number of studies have demonstrated that ketamine induces rapid and sustained antidepressant action. Neuronal nitric oxide synthase (nNOS) signaling has been explored for the treatment of neuropsychiatric disorders for decades. But the effect of ketamine on nNOS signaling is poorly understood. The aim of the present study was to investigate the effect of ketamine on nNOS signaling in a chronic unpredictable mild stress (CUMS) model of depression.

Methods

Forty-eight rats were randomly divided into four groups: the control group of healthy rats (group C), the healthy rats treated with ketamine 10 mg/kg for 3 days (group CK), the rats model of stress-induced depression group (group D), and the depressed group treated with ketamine 10 mg/kg for 3 days (group DK). The sucrose preference test and open field test were used to assess behavioral changes. Immunohistochemistry, immunofluorescence, and real-time PCR analysis were carried out to measure the expression of nNOS, CAPON, and Dexras1 in the prefrontal cortex (PFC) of the CUMS rats.

Results

Compared with healthy rats, the total distance traveled, the rearing counts, the sucrose preference percentage (SPP), and CAPON and Dexras1 expression in the PFC significantly decreased, while nNOS expression increased in CUMS rats. After treating with ketamine, the total distance traveled, the rearing counts, the SPP, and CAPON and Dexras1 expression significantly increased, while nNOS expression significantly decreased.

Conclusion

The results indicated that ketamine improved the depressive behavior of rats, which may be related to the reduced nNOS expression and enhanced CAPON and Dexras1 expression.

Transcriptome Comparison of Brain and Kidney Endothelial Cells in Homeostasis

Endothelial cells are heterogeneous, stemming from multiple organs, but there is still little known about the connection between the brain and kidney endothelial cells, especially in homeostasis. In this study, scRNA-seq results were obtained to compare genetic profiles and biological features of tissue-specific endothelial cells. On this basis, seven endothelial cell subpopulations were identified, two of which were upregulated genes in pathways related to stroke and/or depression, as characterized by neuroinflammation. This study revealed the similarities and distinctions between brain and kidney endothelial cells, providing baseline information needed to fully understand the relationship between renal diseases and neuroinflammation, such as stroke and depression.

Brain Metabolic Profile after Intranasal vs. Intraperitoneal Clomipramine Treatment in Rats with Ultrasound Model of Depression

BACKGROUND

Molecular mechanisms of depression remain unclear. The brain metabolome after antidepressant therapy is poorly understood and had not been performed for different routes of drug administration before the present study. Rats were exposed to chronic ultrasound stress and treated with intranasal and intraperitoneal clomipramine. We then analyzed 28 metabolites in the frontal cortex and hippocampus.

METHODS

Rats' behavior was identified in such tests: social interaction, sucrose preference, forced swim, and Morris water maze. Metabolic analysis was performed with liquid chromatography.

RESULTS

After ultrasound stress pronounced depressive-like behavior, clomipramine had an equally antidepressant effect after intranasal and intraperitoneal administration on behavior. Ultrasound stress contributed to changes of the metabolomic pathways associated with pathophysiology of depression. Clomipramine affected global metabolome in frontal cortex and hippocampus in a different way that depended on the route of administration. Intranasal route was associated with more significant changes of metabolites composition in the frontal cortex compared to the control and ultrasound groups while the intraperitoneal route corresponded with more profound changes in hippocampal metabolome compared to other groups. Since far metabolic processes in the brain can change in many ways depending on different routes of administration, the antidepressant therapy should also be evaluated from this point of view.

Comprehensive Analysis Strategy of Nervous-Endocrine-Immune-Related Metabolites to Evaluate Arachidonic Acid as a Novel Diagnostic Biomarker in Depression

Depression is one of the most complex multifactorial diseases affected by genetic and environmental factors. The molecular mechanism underlying depression remains largely unclear. To address this issue, a novel nervous-endocrine-immune (NEI) network module was used to find the metabolites and evaluate the diagnostic ability of patients with depression. During this process, metabolites were acquired from a professional depression metabolism database. Over-representation analysis was performed using IMPaLA. Then, the metabolite-metabolite interaction (MMI) network of the NEI system was used to select key metabolites. Finally, the receiver operating characteristic curve analysis was evaluated for the diagnostic ability of arachidonic acid. The results show that the numbers of the nervous system, endocrine system, and immune system pathways are 10, 19, and 12 and the numbers of metabolites are 38, 52, and 13, respectively. The selected shared metabolite-enriched pathways can be 97.56% of the NEI-related pathways. Arachidonic acid was extracted from the NEI system network by using an optimization formula and validated by in vivo experiments. It was indicated that the proposed model was good at screening arachidonic acid for the diagnosis of depression. This method provides reliable evidences and references for the diagnosis and mechanism research of other related diseases.

The Association Between Concentrations of Arginine, Ornithine, Citrulline and Major Depressive Disorder: A Meta-Analysis

Alterations in the peripheral (e.g., serum, plasma, platelet) concentrations of arginine and its related catabolic products (i.e., ornithine, citrulline) in the urea and nitric oxide cycles have been reported to be associated with major depressive disorder (MDD). The meta-analysis herein aimed to explore the association between the concentration of peripheral arginine, its catabolic products and MDD, as well as to discuss the possible role of arginine catabolism in the onset and progression of MDD. PubMed, EMBASE, PsycINFO and Web of Science were searched from inception to June 2020. The protocol for the meta-analysis herein has been registered at the Open Science Framework [https://doi.org/10.17605/osf.io/7fn59]. In total, 745 (47.5%) subjects with MDD and 823 (52.5%) healthy controls (HCs) from 13 articles with 16 studies were included. Fifteen of the included studies assessed concentrations of peripheral arginine, eight assessed concentrations of ornithine, and six assessed concentrations of citrulline. Results indicated that: (1) the concentrations of arginine, ornithine, and citrulline were not significantly different between individuals with MDD and HCs when serum, plasma and platelet are analyzed together, (2) in the subgroups of serum samples, the concentrations of arginine were lower in individuals with MDD than HCs, and (3) concurrent administration of psychotropic medications may be a confounding variable affecting the concentrations of arginine, ornithine, and citrulline. Our findings herein do not support the hypothesis that arginine catabolism between individuals with MDD and HCs are significantly different. The medication status and sample types should be considered as a key future research avenue for assessing arginine catabolism in MDD.