(1)H NMR-based metabolomics exploring biomarkers in rat cerebrospinal fluid after cerebral ischemia/reperfusion

Exploring the metabolic implications of blue light exposure during daytime in rats

Excessive exposure to light is a global issue. Artificial light pollution has been shown to disrupt the body's natural circadian rhythm. To investigate the impacts of light on metabolism, we studied Sprague-Dawley rats chronically exposed to red or blue light during daytime or nighttime. Rats in the experimental group were exposed to extended light for 4 hours during daytime or nighttime to simulate the effects of excessive light usage. Strikingly, we found systemic metabolic alterations only induced by blue light during daytime. Furthermore, we conducted metabolomic analyses of the cerebrospinal fluid, serum, heart, liver, spleen, adrenal, cerebellum, pituitary, prostate, spermatophore, hypothalamus and kidney from rats in the control and blue light exposure during daytime. Significant changes in metabolites have been observed in cerebrospinal fluid, serum, hypothalamus and kidney of rats exposed to blue light during daytime. Metabolic alterations observed in rats encompassing pyruvate metabolism, glutathione metabolism homocysteine degradation, phosphatidylethanolamine biosynthesis, and phospholipid biosynthesis, exhibit analogous patterns to those inherent in specific physiological processes, notably neurodevelopment, cellular injury, oxidative stress, and autophagic pathways. Our study provides insights into tissue-specific metabolic changes in rats exposed to blue light during the daytime and may help explain potential mechanisms of photopathogenesis.

Anti-platelet aggregation activities of different grades of Angelica sinensis and their therapeutic mechanisms in rats with blood deficiency: insights from metabolomics and lipidomics analyses

In traditional Chinese medicine, the radix of Angelica sinensis (Oliv.) Diels (RAS) is mainly used to replenish and invigorate the blood circulation. This study investigated anti-platelet aggregation activities were used by New Zealand rabbits, and high-performance liquid chromatography data were obtained to determine the spectrum-effect relationship for different commercial grades of RAS. Plasma and urine metabolites were examined using ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry-based metabolomics to elucidate the mechanisms underlying the role of these metabolites in a rat model of blood deficiency (BD). Plasma and spleen metabolites were additionally examined using ultra-performance liquid chromatography plus Q-Exactive tandem mass spectrometry-based lipidomics to clarify the mechanisms of RAS in treating BD. The third grade of RAS exhibited the best activity in replenishing and invigorating blood in vitro and in vivo. Ferulic acid, ligustilide, senkyunolide I, uridine, and guanine are quality markers of anti-platelet aggregation activity. Based on the metabolomics results, 19 potential biomarkers were screened in plasma, and 12 potential metabolites were detected in urine. In lipidomics analyses, 73 potential biomarkers were screened in plasma, and 112 potential biomarkers were screened in the spleen. RAS may restore lipid metabolism by regulating disorders of glycerophospholipid and sphingolipid metabolism, the tricarboxylic acid cycle, amino acid metabolism (thereby improving energy metabolism), and arachidonic acid metabolism (thereby promoting blood circulation). These results provide a deeper understanding of the effects of different grades of RAS and a scientific reference for the establishment of grading standards and for the clinical use of RAS.

Metabolomics of ischemic stroke: insights into risk prediction and mechanisms

Ischemic stroke (IS) is the most prevalent type of stroke. The early diagnosis and prognosis of IS are crucial for successful therapy and early intervention. Metabolomics, a tool in systems biology based on several innovative technologies, can be used to identify disease biomarkers and unveil underlying pathophysiological processes. Accordingly, in recent years, an increasing number of studies have identified metabolites from cerebral ischemia patients and animal models that could improve the diagnosis of IS and prediction of its outcome. In this paper, metabolomic research is comprehensively reviewed with a focus on describing the metabolic changes and related pathways associated with IS. Most clinical studies use biofluids (e.g., blood or plasma) because their collection is minimally invasive and they are ideal for analyzing changes in metabolites in patients of IS. We review the application of animal models in metabolomic analyses aimed at investigating potential mechanisms of IS and developing novel therapeutic approaches. In addition, this review presents the strengths and limitations of current metabolomic studies on IS, providing a reference for future related studies.

Central and peripheral regulations mediated by short-chain fatty acids on energy homeostasis

The human gut microbiota influences obesity, insulin resistance, and the subsequent development of type 2 diabetes (T2D). The gut microbiota digests and ferments nutrients resulting in the production of short-chain fatty acids (SCFAs), which generate various beneficial metabolic effects on energy and glucose homeostasis. However, their roles in the central nervous system (CNS)-mediated outputs on the metabolism have only been minimally studied. Here, we explore what is known and future directions that may be worth exploring in this emerging area. Specifically, we searched studies or data in English by using PubMed, Google Scholar, and the Human Metabolome Database. Studies were filtered by time from 1978 to March 2022. As a result, 195 studies, 53 reviews, 1 website, and 1 book were included. One hundred and sixty-five of 195 studies describe the production and metabolism of SCFAs or the effects of SCFAs on energy homeostasis, glucose balance, and mental diseases through the gut-brain axis or directly by a central pathway. Thirty of 195 studies show that inappropriate metabolism and excessive of SCFAs are metabolically detrimental. Most studies suggest that SCFAs exert beneficial metabolic effects by acting as the energy substrate in the TCA cycle, regulating the hormones related to satiety regulation and insulin secretion, and modulating immune cells and microglia. These functions have been linked with AMPK signaling, GPCRs-dependent pathways, and inhibition of histone deacetylases (HDACs). However, the studies focusing on the central effects of SCFAs are still limited. The mechanisms by which central SCFAs regulate appetite, energy expenditure, and blood glucose during different physiological conditions warrant further investigation.

Fluid biomarkers in stroke: From animal models to clinical care

Stroke is a leading cause of death and disability worldwide. Stroke prevention, early diagnosis, and efficient acute treatment are priorities to successfully impact stroke death and disability. Fluid biomarkers may improve stroke differential diagnostic, patient stratification for acute treatment, and post-stroke individualized rehabilitation. In the present work, we characterized the use of stroke animal models in fluid biomarker research through a systematic review of PubMed and Scopus databases, followed by a literature review on the translation to the human stroke care setting and future perspectives in the field. We found increasing numbers of publications but with limited translation to the clinic. Animal studies are very heterogeneous, do not account for several human features present in stroke, and, importantly, only a minority of such studies used human cohorts to validate biomarker findings. Clinical studies have found appealing candidates, both protein and circulating nucleic acids, to contribute to a more personalized stroke care pathway. Still, brain tissue complexity and the fact that different brain pathologies share lesion biomarkers make this task challenging due to biomarker low specificity. Moreover, the study design and lack of validation cohorts may have precluded a formal integration of biomarkers in different steps of stroke diagnosis and treatment. To overcome such issues, recent pivotal studies on biomarker dynamics in individual patients are providing added value to diagnosis and anticipating patients' early prognosis. Presently, the most consistent protein biomarkers for stroke diagnosis and short- and long-term prognosis are associated with tissue damage at neuronal (TAU), axonal (NFL), or astroglial (GFAP and S100β) levels. Most promising nucleic acids are microRNAs (miR), due to their stability in plasma and ease of access. Still, clinical validation and standardized quantitation place them a step behind compared protein as stroke biomarkers. Ultimately, the definition of clinically relevant biomarker panels and optimization of fast and sensitive biomarker measurements in the blood, together with their combination with clinical and neuroimaging data, will pave the way toward personalized stroke care.

Metabolomics-Based Pharmacodynamic Analysis of Zhuang Yao Shuang Lu Tong Nao Granules in a Rat Model of Ischemic Cerebral Infarction

This study used a metabolomic approach to reveal changes in the levels of metabolic biomarkers and related metabolic pathways before and after Zhuang Yao Shuang Lu Tong Nao granule (YHT) treatment in rats with cerebral ischemia. The neurological deficit scores were significantly higher in the MCAO_R group than in the NC group, indicating that the mice had significantly impaired motor functions. The YHT group had significantly lower scores than the MCAO_R group, suggesting that YHT significantly improved motor function in rats. TTC staining of the brain tissue revealed that YHT significantly reduced the area of cerebral infarction in the treated rats. The MCAO_R group was better separated from the NC rent, sham, and YHT groups via metabolomic PCA. Moreover, there were significant differences in the differential metabolites between the MACO_R and YHT groups. Eighteen common differential metabolites were detected between the MACO_R and NC groups, MACO_R and sham groups, and MACO_R and YHT groups, indicating that YHT significantly increased the levels of various metabolites in the serum of cerebral ischemic stroke (CIS) rats. Moreover, a total of 23 metabolic pathways were obtained. We identified 11 metabolic pathways with the most significant effects in the bubble plots. In conclusion, from a systems biology perspective, this metabolomics-based study showed that YHT could be used to treat ischemic stroke by modulating changes in endogenous metabolites.

Metabolic Changes Induced by Cerebral Ischemia, the Effect of Ischemic Preconditioning, and Hyperhomocysteinemia

1H Nuclear Magnetic Resonance (NMR) metabolomics is one of the fundamental tools in the fast-developing metabolomics field. It identifies and quantifies the most abundant metabolites, alterations of which can describe energy metabolism, activated immune response, protein synthesis and catabolism, neurotransmission, and many other factors. This paper summarizes our results of the 1H NMR metabolomics approach to characterize the distribution of relevant metabolites and their alterations induced by cerebral ischemic injury or its combination with hyperhomocysteinemia in the affected tissue and blood plasma in rodents. A decrease in the neurotransmitter pool in the brain tissue likely follows the disordered feasibility of post-ischemic neurotransmission. This decline is balanced by the increased tissue glutamine level with the detected impact on neuronal health. The ischemic injury was also manifested in the metabolomic alterations in blood plasma with the decreased levels of glycolytic intermediates, as well as a post-ischemically induced ketosis-like state with increased plasma ketone bodies. As the 3-hydroxybutyrate can act as a likely neuroprotectant, its post-ischemic increase can suggest its supporting role in balancing ischemic metabolic dysregulation. Furthermore, the 1H NMR approach revealed post-ischemically increased 3-hydroxybutyrate in the remote organs, such as the liver and heart, as well as decreased myocardial glutamate. Ischemic preconditioning, as a proposed protective strategy, was manifested in a lower extent of metabolomic changes and/or their faster recovery in a longitudinal study. The paper also summarizes the pre- and post-ischemic metabolomic changes in the rat hyperhomocysteinemic models. Animals are challenged with hyperglycemia and ketosis-like state. A decrease in several amino acids in plasma follows the onset and progression of hippocampal neuropathology when combined with ischemic injury. The 1H NMR metabolomics approach also offers a high potential for metabolites in discriminatory analysis in the search for potential biomarkers of ischemic injury. Based on our results and the literature data, this paper presents valuable findings applicable in clinical studies and suggests the precaution of a high protein diet, especially foods which are high in Met content and low in B vitamins, in the possible risk of human cerebrovascular neuropathology.

Related factors based on non-targeted metabolomics methods in minor ischaemic stroke

OBJECTIVE

This study aimed to identify potential biomarkers associated with the occurrence of minor ischaemic stroke.

METHODS

Four hundred patients hospitalized with minor ischaemic stroke were enrolled in the department of neurological internal medicine in Taiyuan Central Hospital, and 210 healthy subjects examined at the Taiyuan Central Hospital Medical Center during the same period were selected. We collected information on the general demographic characteristics and fasting blood samples of the subjects. We then used untargeted metabolomic assay to measure blood glucose, blood lipids, homocysteine, and high-sensitivity C-reactive protein.

RESULTS

There were statistically significant differences between the mild ischemic stroke group and the healthy control group in smoking, hypertension, and physical activity (P< 0.05). Compared with the healthy group, the minor ischaemic stroke group showed increased lactate, pyruvate, trimetlylamine oxide levels, and lactic acid, pyruvic acid, and trimethylamine N-oxidation (TMAO) levels were statistically significant (P< 0.001). In the minor ischaemic stroke risk model, hypertension, physical activity, smoking, and elevated TMAO levels influenced the occurrence of minor stroke.

CONCLUSION

Increased levels of lactic acid, pyruvate, and TMAO may be related to the pathophysiological changes in the minor ischaemic stroke population. High blood pressure, a lack of physical activity, smoking, and increased TMAO level were the influencing factors for the occurrence of minor ischaemic stroke. The serum metabolite TMAO may be associated with MS occurrence.

Application of Metabolomics to the Discovery of Biomarkers for Ischemic Stroke in the Murine Model: a Comparison with the Clinical Results

Ischemic stroke (IS) is a major cause of mortality and disability worldwide. However, the pathogenesis of IS remains unknown, and methods for early prediction and diagnosis of IS are lacking. Metabolomics can be applied to biomarker discovery and mechanism exploration of IS by exploring metabolic alterations. In this review, 62 IS metabolomics studies in the murine model published from January 2006 to December 2020 in the PubMed and Web of Science databases were systematically reviewed. Twenty metabolites (e.g., lysine, phenylalanine, methionine, tryptophan, leucine, lactate, serine, N-acetyl-aspartic acid, and glutathione) were reported consistently in more than two-third murine studies. The disturbance of metabolic pathways, such as arginine biosynthesis; alanine, aspartate and glutamate metabolism; aminoacyl-tRNA biosynthesis; and citrate cycle, may be implicated in the development of IS by influencing the biological processes such as energy failure, oxidative stress, apoptosis, and glutamate toxicity. The transient middle cerebral artery occlusion model and permanent middle cerebral artery occlusion model exhibit both common and distinct metabolic patterns. Furthermore, five metabolites (proline, serine, LysoPC (16:0), uric acid, glutamate) in the blood sample and 7 metabolic pathways (e.g., alanine, aspartate, and glutamate metabolism) are shared in animal and clinical studies. The potential biomarkers and related pathways of IS in the murine model may facilitate the biomarker discovery for early diagnosis of IS and the development of novel therapeutic targets.

Brain-dead and coma patients exhibit different serum metabolic profiles: preliminary investigation of a novel diagnostic approach in neurocritical care

There is a clear difference between severe brain damage and brain death. However, in clinical practice, the differentiation of these states can be challenging. Currently, there are no laboratory tools that facilitate brain death diagnosis. The aim of our study was to evaluate the utility of serum metabolomic analysis in differentiating coma patients (CP) from individuals with brain death (BD). Serum samples were collected from 23 adult individuals with established diagnosis of brain death and 24 patients in coma with Glasgow Coma Scale 3 or 4, with no other clinical symptoms of brain death for at least 7 days after sample collection. Serum metabolomic profiles were investigated using proton nuclear magnetic resonance (NMR) spectroscopy. The results obtained were examined by univariate and multivariate data analysis (PCA, PLS-DA, and OPLS-DA). Metabolic profiling allowed us to quantify 43 resonance signals, of which 34 were identified. Multivariate statistical modeling revealed a highly significant separation between coma patients and brain-dead individuals, as well as strong predictive potential. The findings not only highlight the potential of the metabolomic approach for distinguishing patients in coma from those in the state of brain death but also may provide an understanding of the pathogenic mechanisms underlying these conditions.

A Urine Metabonomics Study of Rat Bladder Cancer by Combining Gas Chromatography-Mass Spectrometry with Random Forest Algorithm

A urine metabolomics study based on gas chromatography-mass spectrometry (GC-MS) and multivariate statistical analysis was applied to distinguish rat bladder cancer. Urine samples with different stages were collected from animal models, i.e., the early stage, medium stage, and advanced stage of the bladder cancer model group and healthy group. After resolving urea with urease, the urine samples were extracted with methanol and, then, derived with N, O-Bis(trimethylsilyl) trifluoroacetamide and trimethylchlorosilane (BSTFA + TMCS, 99 : 1, v/v), before analyzed by GC-MS. Three classification models, i.e., healthy control vs. early- and middle-stage groups, healthy control vs. advanced-stage group, and early- and middle-stage groups vs. advanced-stage group, were established to analyze these experimental data by using Random Forests (RF) algorithm, respectively. The classification results showed that combining random forest algorithm with metabolites characters, the differences caused by the progress of disease could be effectively exhibited. Our results showed that glyceric acid, 2, 3-dihydroxybutanoic acid, N-(oxohexyl)-glycine, and D-turanose had higher contributions in classification of different groups. The pathway analysis results showed that these metabolites had relationships with starch and sucrose, glycine, serine, threonine, and galactose metabolism. Our study results suggested that urine metabolomics was an effective approach for disease diagnosis.

1 H NMR metabolomic profiling elucidated attenuation of neurometabolic alterations by lercanidipine in MCAo model in rats

OBJECTIVES

Stroke is a leading cause of death and disability worldwide with limited therapeutic interventions. The current study explored proton nuclear magnetic resonance spectroscopy (¹ H NMR)-based metabolomic approach to elucidate the effect of lercanidipine on neurometabolic alterations in transient model of ischaemic stroke in rats.

METHODS

In the present investigation, male Wistar rats were subjected to middle cerebral artery occlusion (MCAo) for 2 h followed by reperfusion using intraluminal filament method. Rats were randomly divided into three groups as vehicle-treated sham control, vehicle-treated MCAo control and lercanidipine-treated MCAo. Vehicle or lercanidipine (0.5 mg/kg, i.p.) was administered 120 min post-reperfusion. The rat brain cortex tissues were isolated 24 h post-MCAo and were investigated by ¹ H NMR spectroscopy through perchloric extraction method.

KEY FINDINGS

A total of 23 metabolites were altered significantly after cerebral ischaemic-reperfusion injury in MCAo control as compared to sham control rats. Lercanidipine significantly reduced the levels of valine, alanine, lactate, acetate and tyrosine, while N-acetylaspartate, glutamate, glutamine, aspartate, creatine/phosphocreatine, choline, glycerophosphorylcholine, taurine, myo-inositol and adenosine di-phosphate were elevated as compared to MCAo control.

CONCLUSIONS

Present study illustrates effect of lercanidipine on neurometabolic alterations which might be mediated through its antioxidant, anti-inflammatory, vasodilatory and anti-apoptotic property in MCAo model of stroke.

Dynamic Alterations of Brain Injury, Functional Recovery, and Metabolites Profile after Cerebral Ischemia/Reperfusion in Rats Contributes to Potential Biomarkers

Cerebral ischemia-reperfusion (I/R) is characterized by initial transient cerebral ischemia followed by reperfusion. Various pathophysiological processes are involved in brain injury and functional recovery during cerebral I/R. There are few studies on dynamic metabolic process after cerebral I/R. The present study was to observe dynamic alteration of brain injury, functional recovery, and metabolites after cerebral I/R in rats and discover potential metabolic markers. The cerebral I/R model was established by middle cerebral artery occlusion (MCAO) for 90 min, following reperfusion in rats. The results of cerebral infarction area, cerebral edema, and behavior test showed that there were dynamic changes in brain injury and functional recovery at different periods after cerebral I/R. Further analysis showed that the brain injury was severe on the first day of cerebral I/R, and there was a significant functional recovery from the 7th day of cerebral I/R, followed by an aggravation trend of brain injury from the days 7 to 28. Furthermore, Matrix-assisted laser desorption ionization mass spectrometry imaging analysis showed that the expression of ATP, glucose, and citric acid on 7th day was the highest during cerebral I/R, which indicated that energy metabolism and oxidative phosphorylation played important roles during cerebral I/R. In addition, the untargeted metabolomic results showed that the level of isocitric acid, the ratio of oxyglutaric acid/glutamic acid, and the level of pyruvic acid associated with the TCA cycle were also the highest on the 7th day during cerebral I/R, which indicated that the transient spontaneous recovery of ischemic brain on the 7th day after ischemia-reperfusion might be related to oxidative phosphorylation and energy metabolism in the brain in this period. In conclusion, the results suggest that some small molecule metabolites participate in the brain injury and functional recovery during cerebral I/R, which is of great significance to the development of therapeutic drugs and diagnostic markers.

Targeted UPLC-MS/MS high-throughput metabolomics approach to assess the purine and pyrimidine metabolism

Purines and pyrimidines, the important components of DNA and RNA, are closely related to metabolic syndrome and disorder, such as renal disease, gout and diabetic nephropathy etc. Given the importance of the biological significance of purines and pyrimidines, it is necessary to further develop a rapid and sensitive method for practical detection of a large-scale analyses. In this study, based on 96-well solid phase extraction plates-ultra performance liquid chromatography-triple quadrupole mass spectrometry (SPE-UPLC-QqQ-MS/MS), a novel approach for simultaneous determination of 23 purines and pyrimidines in biological samples was developed. First, plasma samples were pretreated by SPE using 96-well plates, which lead to an automated, simplified and rapid sample preparation process. In the methodology development, a large-scale test was performed to evaluate the stability and reliability of the approach. Finally, the levels of purines and pyrimidines in the biological samples were analyzed by this strategy. Experimental results showed that lowest limit of quantification (LLOQ) range from 6.678 × 10^-2 μg/mL to 4.275 × 10^-6 μg/mL; intra- and inter-day precision are <15% for all analytes. The stability and maximal capability of a single analytical batch could be extended to at least 431 injections (about 70 h). Analysis time of a single run was controlled in 10 min. Under the optimized conditions, wide linear ranges and good correlation coefficients (R² > 0.99) were acquired. The successful development of this method provides a feasible protocol for a large-scale metabolomics study and it also lays the foundation of quantitative analysis in endogenous analytes.

Integrated Proteomics and Metabolomic Analyses of Plasma Injury Biomarkers in a Serious Brain Trauma Model in Rats

Diffuse axonal injury (DAI) is a prevalent and serious brain injury with significant morbidity and disability. However, the underlying pathogenesis of DAI remains largely unclear, and there are still no objective laboratory-based tests available for clinicians to make an early diagnosis of DAI. An integrated analysis of metabolomic data and proteomic data may be useful to identify all of the molecular mechanisms of DAI and novel potential biomarkers. Therefore, we established a rat model of DAI, and applied an integrated UPLC-Q-TOF/MS-based metabolomics and isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomic analysis to obtain unbiased profiling data. Differential analysis identified 34 metabolites and 43 proteins in rat plasma of the injury group. Two metabolites (acetone and 4-Hydroxybenzaldehyde) and two proteins (Alpha-1-antiproteinase and Alpha-1-acid glycoprotein) were identified as potential biomarkers for DAI, and all may play important roles in the pathogenesis of DAI. Our study demonstrated the feasibility of integrated metabolomics and proteomics method to uncover the underlying molecular mechanisms of DAI, and may help provide clinicians with some novel diagnostic biomarkers and therapeutic targets.

Combined proteomic and metabolomic analyses of cerebrospinal fluid from mice with ischemic stroke reveals the effects of a Buyang Huanwu decoction in neurodegenerative disease

Ischemic stroke is one of the most common causes of death worldwide and is a major cause of acquired disability in adults. However, there is still a need for an effective drug for its treatment. Buyang Huanwu decoction (BHD), a traditional Chinese medicine (TCM) prescription, has long been used clinically to aid neurological recovery after stroke. To establish potential clinical indicators of BHD efficacy in stroke treatment and prognosis, we conducted a combined proteomic and metabolomic analysis of cerebrospinal fluid (CSF) samples in a mouse stroke model. CSF samples were obtained from male mice with acute ischemic stroke induced by middle cerebral ischemic/reperfusion (CI/R) injury, some of which were then treated with BHD. Label-free quantitative proteomics was conducted using nano-LC-MS/MS on an LTQ Orbitrap mass and metabolomic analysis was performed using nanoprobe NMR and UHPLC-QTOF-MS. The results showed that several proteins and metabolites were present at significantly different concentrations in the CSF samples from mice with CI/R alone and those treated with BHD. These belonged to pathways related to energy demand, inflammatory signaling, cytoskeletal regulation, Wnt signaling, and neuroprotection against neurodegenerative diseases. In conclusion, our in silico data suggest that BHD treatment is not only protective but can also ameliorate defects in pathways affected by neurological disorders. These data shed light on the mechanism whereby BHD may be effective in the treatment and prevention of stroke-related neurodegenerative disease.

Dose-dependent target diversion of Danhong injection on the Glu-GLT-1/Gly-GlyRα dynamic balance module of cerebral ischemia

Function-oriented modular structure analysis is a great challenge in module-based pharmacological studies. A strategy to uncover target-target interaction (TTI) and dynamic balance regularity (DBR) was established to discover the structural factors influencing modular functions and explore the mechanism of Danhong injection (DHI) in treating cerebral ischemia. The dose-related metabolic features of DHI intervention were investigated using metabolomics and modular pharmacology. The findings indicated that Glu/Gly was a biomarker and Glu-GLT-1/Gly-GlyRα was the core unit regulated by DHI. Gly and Glu displayed opposite patterns and functional roles, representing intra-modular balance. GlyRα was identified as the upstream target and GLT-1 as the downstream target by inhibiting or activating GlyRα, indicating that DHI has two dose-dependent regulatory modes. GlyRα was the major target at low doses, while GLT-1 was activated as the dominant target as doses accumulated. Our study reveals that target-target interaction and dynamic balance regularity are the key factors influencing modular functions, which is a promising breakthrough for module-based pharmacological studies.

Urine metabolomic profiling of children with respiratory tract infections in the emergency department: a pilot study

BACKGROUND

Clinicians lack objective tests to help determine the severity of bronchiolitis or to distinguish a viral from bacterial causes of respiratory distress. We hypothesized that children with respiratory syncytial virus (RSV) infection would have a different metabolomic profile compared to those with bacterial infection or healthy controls, and this might also vary with bronchiolitis severity.

METHODS

Clinical information and urine-based metabolomic data were collected from healthy age-matched children (n = 37) and those admitted to hospital with a proven infection (RSV n = 55; Non-RSV viral n = 16; bacterial n = 24). Nuclear magnetic resonance (NMR) measured 86 metabolites per urine sample. Partial least squares discriminant analysis (PLS-DA) was performed to create models of separation.

RESULTS

Using a combination of metabolites, a strong PLS-DA model (R2 = 0.86, Q2 = 0.76) was created differentiating healthy children from those with RSV infection. This model had over 90 % accuracy in classifying blinded infants with similar illness severity. Two other models differentiated length of hospitalization and viral versus bacterial infection.

CONCLUSION

While the sample sizes remain small, this is the first report suggesting that metabolomic analysis of urine samples has the potential to become a diagnostic aid. Future studies with larger sample sizes are required to validate the utility of metabolomics in pediatric patients with respiratory distress.

(1)H NMR-based metabonomics revealed protective effect of Naodesheng bioactive extract on ischemic stroke rats

ETHNOPHARMACOLOGICAL RELEVANCE

Stroke is a leading cause of death and disability in the world. However, current therapies are limited. Naodesheng, a widely used traditional Chinese medicine prescription, has shown a good clinical curative effect on ischemic stroke. Also, Naodesheng has been suggested to have neuroprotective effect on focal cerebral ischemia rats, but the underlying molecular mechanism remains unclear.

AIM OF THE STUDY

The present study was designed to evaluate the effect of Naodesheng bioactive extract on the metabolic changes in brain tissue, plasma and urine induced by cerebral ischemia perfusion injury, and explore the possible metabolic mechanisms by using a (1)H NMR-based metabonomics approach.

MATERIALS AND METHODS

A middle cerebral artery occlusion rat model was established and confirmed by the experiments of neurobehavioral abnormality evaluation, brain tissue TTC staining and pathological examination. The metabolic changes in brain tissue, plasma and urine were then assessed by a (1)H NMR technique combined with multivariate statistical analysis method.

RESULTS

These NMR data showed that cerebral ischemia reperfusion induced great metabolic disorders in brain tissue, plasma and urine metabolisms. However, Naodesheng bioactive extract could reverse most of the imbalanced metabolites. Meanwhile, it was found that both the medium and high dosages of Naodesheng bioactive extract were more effective on the metabolic changes than the low dosage, consistent with histopathological assessments.

CONCLUSIONS

These results revealed that Naodesheng had protective effect on ischemic stroke rats and the underlying mechanisms involved multiple metabolic pathways, including energy metabolism, amino acid metabolism, oxidative stress and inflammatory injury. The present study could provide evidence that metabonomics revealed its capacity to evaluate the holistic efficacy of traditional Chinese medicine and explore the underlying mechanisms.

Metabolomic investigation of regional brain tissue dysfunctions induced by global cerebral ischemia

Background

To get a broader view of global ischemia-induced cerebral disorders at the metabolic level, a nuclear magnetic resonance-based metabolomic study was performed to evaluate the metabolic profile changes on regional brain tissues of female and male mice upon bilateral common carotid arteries occlusion (BCCAO) operation.

Results

Significant metabolic disorders were observed in both cerebral cortex and hippocampus tissues of the experimental mice upon global cerebral ischemic attack. Multiple amino acids were identified as the dominantly perturbed metabolites. It was also shown that although the metabolic profile change patterns in the brain tissues were quite similar in male and female BCCAO mice, metabolic disorders in the cortex tissues were more severe in the female mice than in the male mice.

Conclusions

In the present study, significant changes in amino acid metabolic pathways were confirmed in the early stage of global ischemia. Meanwhile, cerebral metabolic dysfunctions were more severe in the female BCCAO mice than in the male mice, suggesting that gender may play a role in different metabolic responses to the ischemic attack, which may provide an important hypothesis for a better understanding of the clinically observed gender-dependent pathological outcome of cerebral ischemia.

Electronic supplementary material

The online version of this article (doi:10.1186/s12868-016-0256-9) contains supplementary material, which is available to authorized users.

An Evidence-Based Review of Related Metabolites and Metabolic Network Research on Cerebral Ischemia

In recent years, metabolomics analyses have been widely applied to cerebral ischemia research. This paper introduces the latest proceedings of metabolomics research on cerebral ischemia. The main techniques, models, animals, and biomarkers of cerebral ischemia will be discussed. With analysis help from the MBRole website and the KEGG database, the altered metabolites in rat cerebral ischemia were used for metabolic pathway enrichment analyses. Our results identify the main metabolic pathways that are related to cerebral ischemia and further construct a metabolic network. These results will provide useful information for elucidating the pathogenesis of cerebral ischemia, as well as the discovery of cerebral ischemia biomarkers.

Metabolomics study on the effects of Buchang Naoxintong capsules for treating cerebral ischemia in rats using UPLC-Q/TOF-MS

ETHNOPHARMACOLOGICAL RELEVANCE

Buchang Naoxintong Capsules (BNC) are widely prescribed in Chinese medicine for the treatment of cerebrovascular and cardiovascular diseases. However, the therapeutic effects and mechanisms are not yet well understood.

MATERIALS AND METHODS

In this study, a UPLC/TOF-MS-based metabolomic study was conducted to explore potential biomarkers that will increase our understanding of cerebral ischemia and to assess the integral efficacy of BNC in a middle cerebral artery occlusion (MCAO) rat model. Plasma metabolic profiles were analyzed and metabolic biomarkers were identified through multivariate data analysis.

RESULTS

Clear separations were observed between the sham, MCAO and BNC-treated groups. We identified 28 biomarkers in the MCAO rats using variable importance for the projections (VIP) values (VIP>1) and a t-test (P<0.05). The identified biomarkers were mainly related to disturbances in monoamine neurotransmitter metabolism, amino acid metabolism, energy metabolism and lipid metabolism. Moreover, a correlation network diagram of the plasma biomarkers perturbed by MCAO was constructed. Some biomarkers, such as glutamine, PE (17:0), LysoPE (20:1), LysoPE (24:0), and the ratios of LysoPE (24:1) to LysoPE (24:0), LysoPE (24:2) to LysoPE (24:0), showed obvious changes and a tendency for returning to baseline values in BNC-treated MCAO rats. In addition, MCAO rats receiving BNC treatment had improved neurological deficits and reduced cerebral infarct size demonstrating the therapeutic potential of BNC for treating cerebral ischemia.

CONCLUSION

This study provides a useful approach for exploring the mechanism of MCAO-induced cerebral ischemia and evaluating the efficacy of BNC.

N-acetylaspartate decrease in acute stage of ischemic stroke: a perspective from experimental and clinical studies

N-acetylaspartate (NAA) appears in a prominent peak in proton magnetic resonance spectroscopy ((1)H-MRS) of the brain. Exhibition by NAA of time-dependent attenuation that reflects energy metabolism during the acute stage of cerebral ischemia makes this metabolite a unique biomarker for assessing ischemic stroke. Although magnetic resonance (MR) imaging is a powerful technique for inspecting the pathological changes that occur during ischemic stroke, biomarkers that directly reflect the drastic metabolic changes associated with acute-stage ischemia are strongly warranted for appropriate therapeutic decision-making in daily clinical settings. In this review, we provide a brief overview of NAA metabolism and focus on the use of attenuation in NAA as a means for assessing the pathophysiological changes that occur during the acute stage of ischemic stroke.

Gas chromatography-mass spectrometry-based metabolic profiling of cerebrospinal fluid from epileptic dogs

Epilepsy is a common neurological disorder with seizures, but diagnostic approaches in veterinary clinics remain limited. Cerebrospinal fluid (CSF) is a body fluid used for diagnosis in veterinary medicine. In this study, we explored canine epilepsy diagnostic biomarkers using gas chromatography-mass spectrometry (GC-MS)-based metabolic profiling of CSF and multivariate data analysis. Profiles for subjects with idiopathic epilepsy differed significantly from those of healthy controls and subjects with symptomatic epilepsy. Among 60 identified metabolites, the levels of 20 differed significantly among the three groups. Glutamic acid was significantly increased in idiopathic epilepsy, and some metabolites including ascorbic acid were changed in both forms of epilepsy. These findings show that metabolic profiles of CSF differ between idiopathic and symptomatic epilepsy and that metabolites including glutamic acid and ascorbic acid in CSF may be useful for diagnosis of canine epilepsy.