Urinary volatilome analysis in a mouse model of anxiety and depression

Exposure to volatile organic compounds and suicidal ideation: Insights from a U.S. population-based study

BACKGROUND

Exposure to volatile organic compounds (VOCs) has been increasingly linked to mental health disorders, but the relationship between VOCs exposure and suicidal ideation (SI) remains unclear. This study aims to investigate the link between VOCs exposure and the prevalence of SI.

METHODS

We analyzed data from 6966 participants in the 2005-2020 National Health and Nutrition Examination Survey. SI was assessed using the ninth item of the Patient Health Questionnaire-9. Key urinary metabolites of VOCs (mVOCs) associated with SI were identified using elastic net regression models. Multivariate logistic regression and restricted cubic spline were used to explore associations between individual mVOCs and SI. To evaluate the impact of mVOCs mixtures on SI, we applied Environmental Risk Score and Weighted Quantile Sum models. Mediation analysis was conducted to determine whether inflammation and oxidative stress pathways contribute to the observed associations.

RESULTS

Among the participants, 253 reported SI. Across various models, only the urinary N-Acetyl-S-(2-cyanoethyl)-L-cysteine (CYMA) consistently showed a significant linear association with SI. Mixture analyses indicated a significant positive association between mVOCs mixtures and SI prevalence. Mediation analysis suggested that inflammation and oxidative stress are unlikely to be the primary mechanisms linking mVOCs exposure to SI.

CONCLUSION

This study provides the first epidemiological evidence of an association between mVOCs exposure and SI. CYMA was identified as the most critical mVOCs influencing SI. The findings suggest that the link between mVOCs exposure and SI does not primarily involve inflammation or oxidative stress pathways.

IUPHAR review: Eating disorders, gut microbiota dysbiosis and epigenetic aberrations

Eating disorders (EDs) are a heterogeneous class of increasing mental disorders that are characterized by disturbances in eating behaviors, body weight regulation, and associated psychological dysfunctions. These disorders create physiological imbalances that alter the diversity and composition of the gut microbiota. While evidence suggests that EDs can arise from epigenetic aberrations, alterations in gut microbial communities may also contribute to the development and/or persistence of EDs through epigenetic mechanisms. Understanding the interplay among gut microbial communities, epigenetic processes, and the risk of EDs provides opportunities for designing preventive and/or therapeutic interventions through gut microbiome modulation. This review highlights how microbiome-based therapeutics and specific dietary interventions can contribute to improving various subtypes of EDs by modulating gut microbial communities and mitigating epigenetic aberrations. First, we briefly review the literature on links between epigenetic aberrations and the pathophysiology of EDs. Second, we examine the potential role of the gut microbiome in the pathogenesis of EDs through epigenetic mechanisms. Next, we explore the associations between EDs and other psychiatric disorders, and examine the potential roles of the microbiome in their pathogenesis. Finally, we present evidence supporting the potential of microbiome-based therapeutics and specific dietary interventions to improve EDs through epigenetic modifications.

ST3 beta-galactoside alpha-2,3-sialyltransferase 4 (St3gal4) deficiency reveals correlations among alkaline phosphatase activity, metabolic parameters, and fear-related behavior in mice

ST3 beta-galactoside alpha-2,3-sialyltransferase 4 (ST3GAL4) is a sialyltransferase involved in the biosynthesis of alpha2,3-sialic acid on glycoproteins and glycolipids. In mice, St3gal4 gene expression plays a crucial role in modulating epilepsy and anxiety/depression through its expression in thalamic neurons. Genome-wide association studies (GWAS) have identified several peripheral metabolic traits strongly associated with ST3GAL4 in humans. However, whether the symptoms observed in mice are associated with metabolic changes remains unclear. This study investigated the effects of St3gal4 deficiency on the same metabolic parameters in mice as those in humans. The parameters examined included body weight, plasma biochemistry, specifically alkaline phosphatase (ALP), protein, and cholesterol levels, and free amino acids profiles, resulting in elevated ALP and reduced tryptophan and total cholesterol (T-Cho) levels in St3gal4-knockout (KO) mice. Additionally, clearance of blood glucose was delayed in KO male mice. These findings suggest mouse St3gal4 deficiency correlated with modulated ALP, tryptophan, and T-Cho levels in the plasma. Next, brain ALP activity was compared between St3gal4-KO mice and wild-type (WT) mice, focusing on the thalamus. Fear conditioning tests assessed the relationship between behavior and ALP activity in plasma and brain. In KO mice, the enhanced tone freezing positively correlated with plasma ALP levels. Conversely, thalamic ALP activity was greatly reduced in KO mice, negatively correlating with plasma ALP. These findings suggest that mouse St3gal4 deficiency influences ALP activity in both thalamus and plasma, associating with emotional behaviors and metabolic changes.

Urinary odor molecules in the Otassha Study can distinguish patients with sarcopenia: A pilot study

AIM

To identify sarcopenia markers in urinary odor.

METHODS

We performed solid-phase microextraction from the headspace and gas chromatography-mass spectrometry analysis of urinary volatile organic compounds (VOCs) in 71 healthy individuals and 68 patients diagnosed with sarcopenia according to the Asian Working Group on Sarcopenia 2019 criteria. The mass-to-charge ratios (m/z) of 10 VOCs with a significant difference in the total ion chromatogram of 220 VOCs detected in this study were compared by U-test. To calculate the predictive values for sarcopenia, binomial logistic regression analyses were conducted with sarcopenia (0, 1) as the dependent variable and the m/z values of each of the 10 VOCs and all 10 VOCs as independent variables. Receiver operating characteristic (ROC) curves for predictive values were generated to evaluate diagnostic accuracy. The correlations between the predictive value and handgrip strength, usual gait speed, and skeletal muscle mass were assessed using Pearson's r.

RESULTS

We identified 10 VOCs (p-xylene, 1-butanol, d-limonene, nonanal, pyrrole, γ-butyrolactone, texanol isomer, octanoic acid, nonanoic acid, and diisobutyl phthalate) as candidate biomarkers in urine. The ROC curve analysis showed high diagnostic accuracy of the predictive values of the 10 VOCs for sarcopenia (area under the curve = 0.866, 95% confidence interval: 0.829-0.942; sensitivity, 80.9%; specificity, 81.7%). Additionally, the predictive values significantly correlated with handgrip strength (male: r = -0.505, P < 0.0001; female: r = -0.568, P < 0.0001).

CONCLUSIONS

This study identified 10 urinary VOCs as possible non-invasive biomarkers for sarcopenia, offering insights into its onset mechanism and potential therapeutic targets. Geriatr Gerontol Int 2025; 25: 307-315.

Partial role of volatile organic compounds in behavioural responses of mice to bedding from cancer-affected congeners

Tumours induce changes in body odours. We compared volatile organic compounds (VOCs) in soiled bedding of a lung adenocarcinoma male mouse model in which cancer had (CC) versus had not (NC) been induced by doxycycline at three conditions: before (T0), after 2 weeks (T2; early tumour development), after 12 weeks (T12; late tumour development) of the induction. In an earlier study, wild-derived mice behaviourally discriminated between CC and NC soiled bedding at T2 and T12. Here, we sought to identify VOCs present in the same soiled bedding that could have triggered the behavioural discrimination. Solid phase micro-extraction was performed to extract VOCs from 3 g-sample stimuli. While wild-derived mice could discriminate the odour of cancerous mice at a very early stage of tumour development (T2), the present study did not identify VOCs that could explain this behaviour. However, consistent with the earlier behavioural study, four VOCs, including two well-known male mouse sex pheromones, were found to be present in significantly different proportions in soiled bedding of CC as compared to NC at T12. We discuss the potential involvement of non-volatile molecules such as proteins and peptides in behavioural discrimination of early tumour development (T2), and point-out VOCs that could help diagnose cancer.

Microbial, proteomic, and metabolomic profiling of the estrous cycle in wild house mice

Symbiotic microbial communities affect the host immune system and produce molecules contributing to the odor of an individual. In many mammalian species, saliva and vaginal fluids are important sources of chemical signals that originate from bacterial metabolism and may act as honest signals of health and reproductive status. In this study, we aimed to define oral and vaginal microbiomes and their dynamics throughout the estrous cycle in wild house mice. In addition, we analyzed a subset of vaginal proteomes and metabolomes to detect potential interactions with microbiomes. 16S rRNA sequencing revealed that both saliva and vagina are dominated by Firmicutes and Proteobacteria but differ at the genus level. The oral microbiome is more stable during the estrous cycle and most abundant bacteria belong to the genera Gemella and Streptococcus, while the vaginal microbiome shows higher bacterial diversity and dynamics during the reproductive cycle and is characterized by the dominance of Muribacter and Rodentibacter. These two genera cover around 50% of the bacterial community during estrus. Proteomic profiling of vaginal fluids revealed specific protein patterns associated with different estrous phases. Highly expressed proteins in estrus involve the keratinization process thus providing estrus markers (e.g., Hrnr) while some proteins are downregulated such as immune-related proteins that limit bacterial growth (Camp, Clu, Elane, Lyz2, and Ngp). The vaginal metabolome contains volatile compounds potentially involved in chemical communication, for example, ketones, aldehydes, and esters of carboxylic acids. Data integration of all three OMICs data sets revealed high correlations, thus providing evidence that microbiomes, host proteomes, and metabolomes may interact.IMPORTANCEOur data revealed dynamic changes in vaginal, but not salivary, microbiome composition during the reproductive cycle of wild mice. With multiple OMICs platforms, we provide evidence that changes in microbiota in the vaginal environment are accompanied by changes in the proteomic and metabolomics profiles of the host. This study describes the natural microbiota of wild mice and may contribute to a better understanding of microbiome-host immune system interactions during the hormonal and cellular changes in the female reproductive tract. Moreover, analysis of volatiles in the vaginal fluid shows particular substances that can be involved in chemical communication and reproductive behavior.

Urinary VOCs as biomarkers of early stage lung tumour development in mice

BACKGROUND

Lung cancer is the primary cause of cancer-induced death. In addition to prevention and improved treatment, it has increasingly been established that early detection is critical to successful remission.

OBJECTIVE

The aim of this study was to identify volatile organic compounds (VOCs) in urine that could help diagnose mouse lung cancer at an early stage of its development.

METHODS

We analysed the VOC composition of urine in a genetically engineered lung adenocarcinoma mouse model with oncogenic EGFR doxycycline-inducible lung-specific expression. We compared the urinary VOCs of 10 cancerous mice and 10 healthy mice (controls) before and after doxycycline induction, every two weeks for 12 weeks, until full-blown carcinomas appeared. We used SPME fibres and gas chromatography - mass spectrometry to detect variations in cancer-related urinary VOCs over time.

RESULTS

This study allowed us to identify eight diagnostic biomarkers that help discriminate early stages of cancer tumour development (i.e., before MRI imaging techniques could identify it).

CONCLUSION

The analysis of mice urinary VOCs have shown that cancer can induce changes in odour profiles at an early stage of cancer development, opening a promising avenue for early diagnosis of lung cancer in other models.

Noninvasive Detection of Stress by Biochemical Profiles from the Skin

Stress is a leading cause of several disease types, yet it is underdiagnosed as current diagnostic methods are mainly based on self-reporting and interviews that are highly subjective, inaccurate, and unsuitable for monitoring. Although some physiological measurements exist (e.g., heart rate variability and cortisol), there are no reliable biological tests that quantify the amount of stress and monitor it in real time. In this article, we report a novel way to measure stress quickly, noninvasively, and accurately. The overall detection approach is based on measuring volatile organic compounds (VOCs) emitted from the skin in response to stress. Sprague Dawley male rats (n = 16) were exposed to underwater trauma. Sixteen naive rats served as a control group (n = 16). VOCs were measured before, during, and after induction of the traumatic event, by gas chromatography linked with mass spectrometry determination and quantification, and an artificially intelligent nanoarray for easy, inexpensive, and portable sensing of the VOCs. An elevated plus maze during and after the induction of stress was used to evaluate the stress response of the rats, and machine learning was used for the development and validation of a computational stress model at each time point. A logistic model classifier with stepwise selection yielded a 66-88% accuracy in detecting stress with a single VOC (2-hydroxy-2-methyl-propanoic acid), and an SVM (support vector machine) model showed a 66-72% accuracy in detecting stress with the artificially intelligent nanoarray. The current study highlights the potential of VOCs as a noninvasive, automatic, and real-time stress predictor for mental health.

A novel set of volatile urinary biomarkers for late-life major depressive and anxiety disorders upon the progression of frailty: a pilot study

Mood and anxiety disorders are frequent in the elderly and increase the risk of frailty. This study aimed to identify novel biomarkers of major depressive disorder (MDD) and anxiety in the elderly. We examined 639 participants in the community-dwelling Otassha Study (518 individuals considered healthy control, 77 with depression, anxiety, etc.), mean age 75 years, 58.4% of female. After exclusion criteria, we analyzed VOCs from 18 individuals (9 healthy control, 9 of MDD/agoraphobia case). Urinary volatile and semi-volatile organic compounds (VOCs) were profiled using solid-phase microextraction and gas chromatography-mass spectrometry. Six urinary VOCs differed in the absolute area of the base peak between participants with MDD and/or agoraphobia and controls. High area under the receiver-operating characteristic curve (AUC) values were found for phenethyl isothiocyanate (AUC: 0.86, p = 0.009), hexanoic acid (AUC: 0.85, p = 0.012), texanol (AUC: 0.99, p = 0.0005), and texanol isomer (AUC: 0.89, p = 0.005). The combined indices of dimethyl sulfone, phenethyl isothiocyanate, and hexanoic acid, and texanol and texanol isomer showed AUCs of 0.91 (p = 0.003) and 0.99 (p = 0.0005) and correlated with the GRID-HAMD and the Kihon Checklist (CL score), respectively. These VOCs may be valuable biomarkers for evaluating MDD and/or agoraphobia in the elderly.

Individuals Diagnosed with Binge-Eating Disorder Have DNA Hypomethylated Sites in Genes of the Metabolic System: A Pilot Study

Binge-eating disorder, recently accepted as a diagnostic category, is differentiated from bulimia nervosa in that the former shows the presence of binge-eating episodes and the absence of compensatory behavior. Epigenetics is a conjunct of mechanisms (like DNA methylation) that regulate gene expression, which are dependent on environmental changes. Analysis of DNA methylation in eating disorders shows that it is reduced. The present study aimed to analyze the genome-wide DNA methylation differences between individuals diagnosed with BED and BN. A total of 46 individuals were analyzed using the Infinium Methylation EPIC array. We found 11 differentially methylated sites between BED- and BN-diagnosed individuals, with genome-wide significance. Most of the associations were found in genes related to metabolic processes (ST3GAL4, PRKAG2, and FRK), which are hypomethylated genes in BED. Cg04781532, located in the body of the PRKAG2 gene (protein kinase AMP-activated non-catalytic subunit gamma 2), was hypomethylated in individuals with BED. Agonists of PRKAG2, which is the subunit of AMPK (AMP-activated protein kinase), are proposed to treat obesity, BED, and BN. The present study contributes important insights into the effect that BED could have on PRKAG2 activation.

Review on Volatolomic Studies as a Frontier Approach in Animal Research

This paper presents a comprehensive review of the research studies in volatolomics performed on animals so far. At first, the procedures proposed for the collection, preconcentration, and storing of the volatile organic compounds emitted by various biological samples of different animals are presented and discussed. Next, the results obtained in the analysis of the collected volatile samples with analytical equipment are shown. The possible volatile biomarkers identified for various diseases are highlighted for different types of diseases, animal species, and biological samples analyzed. The chemical classes of these compounds, as well as the biomarkers found in a higher number of animal diseases, are indicated, and their possible origin is analyzed. The studies that dealt with the diagnosis of various diseases from sample measurement with electronic nose systems are also presented and discussed. The paper ends with a final remark regarding the necessity of optimization and standardization of sample collection and analysis procedures for obtaining meaningful results.

HDAC1-Mediated MicroRNA-124-5p Regulates NPY to Affect Learning and Memory Abilities in Rats with Depression

Researches pivoting on histone deacetylases (HDACs) in depression have been excessively conducted, but not much on HDAC1. Therein, the present study is launched to disclose the mechanism of HDAC1/microRNA (miR)-124-5p/neuropeptide Y (NPY) axis in depression. Sprague Dawley rats were stimulated by chronic unpredictable mild stress to establish depression models. Depressed rats were injected with inhibited HDAC1 or suppressed miR-124-5p to explore their roles in body weight, learning and memory abilities, oxidative stress and inflammation in serum and neurotransmitter expression in hippocampal tissues. MiR-124-5p, HDAC1 and NPY expression in the hippocampus were tested. The interactions of miR-124-5p, HDAC1 and NPY expression were also confirmed. Higher miR-124-5p and HDAC1 and lower NPY expression levels were found in the hippocampus of depressed rats. Inhibited miR-124-5p or suppressed HDAC1 attenuated learning and memory abilities and increased body weight of depressed rats. Knockdown of miR-124-5p or inhibition of HDAC1 suppressed oxidative stress and inflammation and promoted neurotransmitter expression of depressed rats. HDAC1 mediated miR-124-5p to regulate NPY. Knockdown of NPY abolished the protective effects of inhibited miR-124-5p on depressed rats. Our study illustrates that suppression of either miR-124-5p or HDAC1 up-regulates NPY to improve memory and learning abilities in depressed mice, which may update the existed knowledge of depression and provide a novel reference for treatment of depression.