Frontal Cortex Myo-Inositol Is Associated with Sleep and Depression in Adolescents: A Proton Magnetic Resonance Spectroscopy Study

Proton magnetic resonance spectroscopy of N-acetyl aspartate in first depressive episode and chronic major depressive disorder: A systematic review and meta-analysis

N-acetyl aspartate (NAA) is a marker of neuronal integrity and metabolism. Deficiency in neuronal plasticity and hypometabolism are implicated in Major Depressive Disorder (MDD) pathophysiology. To test if cerebral NAA concentrations decrease progressively over the MDD course, we conducted a pre-registered meta-analysis of Proton Magnetic Resonance Spectroscopy (1H-MRS) studies comparing NAA concentrations in chronic MDD (n = 1308) and first episode of depression (n = 242) patients to healthy controls (HC, n = 1242). Sixty-two studies were meta-analyzed using a random-effect model for each brain region. NAA concentrations were significantly reduced in chronic MDD compared to HC within the frontal lobe (Hedges' g = -0.330; p = 0.018), the occipital lobe (Hedges' g = -0.677; p = 0.007), thalamus (Hedges' g = -0.673; p = 0.016), and frontal (Hedges' g = -0.471; p = 0.034) and periventricular white matter (Hedges' g = -0.478; p = 0.047). We highlighted a gap of knowledge regarding NAA levels in first episode of depression patients. Sensitivity analyses indicated that antidepressant treatment may reverse NAA alterations in the frontal lobe. We highlighted field strength and correction for voxel grey matter as moderators of NAA levels detection. Future studies should assess NAA alterations in the early stages of the illness and their longitudinal progression.

Brain metabolite levels in remitted psychotic depression with consideration of effects of antipsychotic medication

BACKGROUND

The neurobiology of psychotic depression is not well understood and can be confounded by antipsychotics. Magnetic resonance spectroscopy (MRS) is an ideal tool to measure brain metabolites non-invasively. We cross-sectionally assessed brain metabolites in patients with remitted psychotic depression and controls. We also longitudinally assessed the effects of olanzapine versus placebo on brain metabolites.

METHODS

Following remission, patients with psychotic depression were randomized to continue sertraline + olanzapine (n = 15) or switched to sertraline + placebo (n = 18), at which point they completed an MRS scan. Patients completed a second scan either 36 weeks later, relapse, or discontinuation. Where water-scaled metabolite levels were obtained and a Point-RESolved Spectroscopy sequence was utilized, choline, myo-inositol, glutamate + glutamine (Glx), N-acetylaspartate, and creatine were measured in the left dorsolateral prefrontal cortex (L-DLPFC) and dorsal anterior cingulate cortex (dACC). An ANCOVA was used to compare metabolites between patients (n = 40) and controls (n = 46). A linear mixed-model was used to compare olanzapine versus placebo groups.

RESULTS

Cross-sectionally, patients (compared to controls) had higher myo-inositol (standardized mean difference [SMD] = 0.84; 95%CI = 0.25-1.44; p = 0.005) in the dACC but not different Glx, choline, N-acetylaspartate, and creatine. Longitudinally, patients randomized to placebo (compared to olanzapine) showed a significantly greater change with a reduction of creatine (SMD = 1.51; 95%CI = 0.71-2.31; p = 0.0002) in the dACC but not glutamate + glutamine, choline, myo-inositol, and N-acetylaspartate.

CONCLUSIONS

Patients with remitted psychotic depression have higher myo-inositol than controls. Olanzapine may maintain creatine levels. Future studies are needed to further disentangle the mechanisms of action of olanzapine.

Biological Properties of Cyclitols and Their Derivatives

Cyclitols are polyhydroxy cycloalkanes, each containing at least three hydroxyls attached to a different ring carbon atom. The most important cyclitol derivatives are inositols, quercitols, conduritols and pinitols, which form a group of naturally occurring polyhydric alcohols and are widely found in plants. In addition, synthetic production of cyclitols has gained importance in recent years. Cylitols are molecules synthesized in plants as a precaution against salt or water stress. They have important functions in cell functioning as they exhibit important properties such as membrane biogenesis, ion channel physiology, signal transduction, osmoregulation, phosphate storage, cell wall formation and antioxidant activity. The biological activities of these very important molecules, obtained both synthetically and from the extraction of plants, are described in this review.

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.

Suprachiasmatic nucleus functional connectivity related to insomnia symptoms in adolescents with major depressive disorder

Background

Insomnia is a commonly seen symptom in adolescents with major depressive disorder (MDD). The suprachiasmatic nucleus (SCN), which is the circadian rhythm regulation center, plays a crucial role in the regulation of sleep-wake circulation. Nevertheless, how SCN function contributes to the exact neural mechanisms underlying the associations between insomnia and depressive symptoms has not been explored in adolescents. In the current study, we aimed to explore the relationship between SCN functional connectivity (FC) and insomnia symptoms in adolescents with MDD using a seed-based FC method.

Methods

In the current study, we recruited sixty-eight first-episode drug-naïve adolescents with MDD and classified them into high insomnia (MDD-HI) and low insomnia (MDD-LI) groups according to the sleep disturbance subscale of the Hamilton Depression Rating Scale (HAMD-S). Forty-three age/gender-matched healthy controls (HCs) were also recruited. SCN FC maps were generally for all subjects and compared among three groups using one-way ANOVA with age, gender and adjusted HAMD score as covariates. We used partial correlations to explore associations between altered FC and clinical symptoms, including sleep quality scores.

Results

Adolescents with MDD showed worse sleep quality, which positively correlated with the severity of depression. Compared to MDD-LI and HCs, MDD-HI adolescents demonstrated significantly decreased FC between the right SCN and bilateral precuneus, and there was no significant difference between the MDD-LI and HC groups. The HAMD-S scores were negatively correlated with bilateral SCN-precuneus connectivity, and the retardation factor score of HAMD was negatively correlated with right SCN-precuneus connectivity.

Conclusion

The altered FC between the SCN and precuneus may underline the neural mechanism of sleep-related symptoms in depressive adolescents and provide potential targets for personalized treatment strategies.

Molecular targets and mechanisms involved in the action of Banxia Shumi decoction in insomnia treatment

Insomnia is a common sleep-wake rhythm disorder, which is closely associated with the occurrence of many serious diseases. Recent researches suggest that circadian rhythms play an important role in regulating sleep duration and sleep quality. Banxia Shumi decoction (BSXM) is a well-known Chinese formula used to treat insomnia in China. However, the overall molecular mechanism behind this therapeutic effect has not yet been fully elucidated. This study aimed to identify the molecular targets and mechanisms involved in the action of BSXM during the treatment of insomnia. Using network pharmacology and molecular docking methods, we investigated the molecular targets and underlying mechanisms of action of BSXM in insomnia therapy. We identified 8 active compounds from Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform and the traditional Chinese medicine integrative database that corresponded to 26 target genes involved in insomnia treatment. The compound-differentially expressed genes of the BXSM network indicated that cavidine and gondoic acid could potentially become key components of drugs used for insomnia treatment. Further analysis revealed that GSK3B, MAPK14, IGF1R, CCL5, and BCL2L11 were core targets significantly associated with the circadian clock. Pathway enrichment analysis of Kyoto Encyclopedia of Genes and Genomes revealed that epidermal growth factor receptor tyrosine kinase inhibitor resistance was the most prominently enriched pathway for BSXM in the insomnia treatment. The forkhead box O signaling pathway was also found to be significantly enriched. These targets were validated using the Gene Expression Omnibus dataset. Molecular docking studies were performed to confirm the binding of cavidine and gondoic acid to the identified core targets. To our knowledge, our study confirmed for the first time that the multi-component, multi-target, and multi-pathway characteristics of BXSM may be the potential mechanism for treating insomnia with respect to the circadian clock gene. The results of this study provided theoretical guidance for researchers to further explore its mechanism of action.

Regional metabolic heterogeneity in anterior cingulate cortex in major depressive disorder: A multi-voxel 1H magnetic resonance spectroscopy study

BACKGROUND

Previous studies have shown major depressive disorder (MDD) is associated with altered neuro-metabolites in the anterior cingulate cortex (ACC). However, the regional metabolic heterogeneity in the ACC in individuals with MDD remains unclear.

METHODS

We recruited 59 first-episode, treatment-naive young adults with MDD and 50 healthy controls who underwent multi-voxel ¹H-MRS scanning at 3 T (Tesla) with voxels placed in the ACC, which was divided into two subregions, pregenual ACC (pACC) and anterior midcingulate cortex (aMCC). Between and within-subjects metabolite concentration variations were analyzed with SPSS.

RESULTS

Compared with control subjects, patients with MDD exhibited higher glutamate (Glu) and glutamine (Gln) levels in the pACC and higher myo-inositol (MI) level in the aMCC. We observed higher Glu and Gln levels and lower N-acetyl-aspartate (NAA) level in the pACC than those in the aMCC in both MDD and healthy control (HC) groups. More importantly, the metabolite concentration gradients of Glu, Gln and NAA were more pronounced in MDD patients relative to HCs. In the MDD group, the MI level in the aMCC positively correlated with the age of onset.

LIMITATIONS

The use of the relative concentration of metabolites constitutes a key study limitation.

CONCLUSIONS

We observed inconsistent alterations and distribution of neuro-metabolites concentration in the pACC and aMCC, revealing regional metabolic heterogeneity of ACC in first-episode, treatment-naive young individuals with MDD. These results provided new evidence for abnormal neuro-metabolites of ACC in the pathophysiology of MDD and suggested that pACC and aMCC might play different roles in MDD.

Mental Health Symptom Reduction Using Digital Therapeutics Care Informed by Genomic SNPs and Gut Microbiome Signatures

Neuropsychiatric diseases and obesity are major components of morbidity and health care costs, with genetic, lifestyle, and gut microbiome factors linked to their etiology. Dietary and weight-loss interventions can help improve mental health, but there is conflicting evidence regarding their efficacy; and moreover, there is substantial interindividual heterogeneity that needs to be understood. We aimed to identify genetic and gut microbiome factors that explain interindividual differences in mental health improvement after a dietary and lifestyle intervention for weight loss. We recruited 369 individuals participating in Digbi Health’s personalized digital therapeutics care program and evaluated the association of 23 genetic scores, the abundance of 178 gut microbial genera, and 42 bacterial pathways with mental health. We studied the presence/absence of anxiety or depression, or sleep problems at baseline and improvement on anxiety, depression, and insomnia after losing at least 2% body weight. Participants lost on average 5.4% body weight and >95% reported improving mental health symptom intensity. There were statistically significant correlations between: (a) genetic scores with anxiety or depression at baseline, gut microbial functions with sleep problems at baseline, and (b) genetic scores and gut microbial taxa and functions with anxiety, depression, and insomnia improvement. Our results are concordant with previous findings, including the association between anxiety or depression at baseline with genetic scores for alcohol use disorder and major depressive disorder. As well, our results uncovered new associations in line with previous epidemiological literature. As evident from previous literature, we also observed associations of gut microbial signatures with mental health including short-chain fatty acids and bacterial neurotoxic metabolites specifically with depression. Our results also show that microbiome and genetic factors explain self-reported mental health status and improvement better than demographic variables independently. The genetic and microbiome factors identified in this study provide the basis for designing and personalizing dietary interventions to improve mental health.

Novel Chemical and Biological Insights of Inositol Derivatives in Mediterranean Plants

Inositols (Ins) are natural compounds largely widespread in plants and animals. Bio-sinthetically they derive from sugars, possessing a molecular structure very similar to the simple sugars, and this aspect concurs to define them as primary metabolites, even though it is much more correct to place them at the boundary between primary and secondary metabolites. This dichotomy is well represented by the fact that as primary metabolites they are essential cellular components in the form of phospholipid derivatives, while as secondary metabolites they are involved in a plethora of signaling pathways playing an important role in the surviving of living organisms. myo-Inositol is the most important and widespread compound of this family, it derives directly from d-glucose, and all known inositols, including stereoisomers and derivatives, are the results of metabolic processes on this unique molecule. In this review, we report the new insights of these compounds and their derivatives concerning their occurrence in Nature with a particular emphasis on the plant of the Mediterranean area, as well as the new developments about their biological effectiveness.

MYO-Inositol In Fermented Sugar Matrix Improves Human Macrophage Function

SCOPE

Reactive oxygen species production by innate immune cells plays a central role in host defense against invading pathogens at wound-site. A weakened hos-defense results in persistent infection leading to wound chronicity. Fermented Papaya Preparation (FPP), a complex sugar matrix, bolstered respiratory burst activity and improved wound healing outcomes in chronic wound patients. The objective of the current study was to identify underlying molecular factor/s responsible for augmenting macrophage host defense mechanisms following FPP supplementation.

METHODS AND RESULTS

In depth LC-MS/MS analysis of cells supplemented with FPP led to identification of myo-inositol as a key determinant of FPP activity towards improving macrophage function. Myo-inositol, in quantities that is present in FPP, significantly improved macrophage respiratory burst and phagocytosis via de novo synthesis pathway of ISYNA1. Additionally, myo-inositol transporters, HMIT and SMIT1, played a significant role in such activity. Blocking these pathways using siRNA attenuated FPP-induced improved macrophage host defense activities. FPP supplementation emerges as a novel approach to increase intracellular myo-inositol levels. Such supplementation also modified wound microenvironment in chronic wound patients to augment myo-inositol levels in wound fluid.

CONCLUSION

These observations indicate that myo-inositol in FPP influences multiple aspects of macrophage function critical for host defense against invading pathogens. This article is protected by copyright. All rights reserved.

The trajectory of putative astroglial dysfunction in first episode schizophrenia: a longitudinal 7-Tesla MRS study

Myo-inositol is mainly found in astroglia and its levels has been shown to be reduced in the anterior cingulate cortex (ACC) of patients with schizophrenia. We investigate the status of astroglial integrity indexed by ACC myo-inositol at the onset and over the first 6 months of treatment of first episode schizophrenia. We employed 7 T magnetic resonance spectroscopy (1H-MRS) and quantified myo-inositol spectra at the dorsal ACC in 31 participants; 21 patients with schizophrenia with median lifetime antipsychotic exposure of less than 3 days, followed up after 6 months of treatment, and 10 healthy subjects scanned twice over the same period. We studied the time by group interaction for myo-inositol after adjusting for gender and age. We report significant reduction in myo-inositol concentration in the ACC in schizophrenia at an early, untreated state of acute illness that becomes insignificant over time, after instituting early intervention. This trajectory indicates that dynamic astroglial changes are likely to operate in the early stages of schizophrenia. MRS myo-inositol may be a critical marker of amelioration of active psychosis in early stages of schizophrenia.

Metabolic changes in the cingulate gyrus, precuneus, and white matter in anorexia nervosa using multivoxel MR spectroscopy

Background and Purpose

This study aimed to highlight anorexia nervosa‐related metabolic changes in different brain regions with different gray and white matter contents.

Methods

In a prospective study, 25 anorexic patients with mean body mass index (BMI) of 14.79 kg/m² (range 10.04–20.58) were compared with 15 healthy controls with mean BMI of 21.08 kg/m² (range 18.36–27.34). Two‐dimensional magnetic resonance spectroscopic imaging was acquired in the axial plane above the corpus callosum, including frontal, precentral, postcentral, cingular, and parietal regions, as well as the precuneus, each voxel containing gray and white matter.

Results

In the anorexic group, a significant increase of choline/creatine was observed in all brain regions except the precuneus: frontal (p = 0.009), cingulate (p = 0.001), precentral (p = 0.001), postcentral (p = 0.001), and parietal (p = 0.002); and in white and gray matter (p< 0.001). Macromolecules09/creatine was decreased in the following regions: frontal (p = 0.003), cingulate (p< 0.001), precentral (p = 0.004), and precuneus (p = 0.007), and in white and gray matter (p< 0.05). We observed significantly lower values of N‐acetyl aspartate/creatine in the frontal (p < 0.001) and precentral (p< 0.001) regions and in voxels containing more than 50% white matter (p = 0.001); and significantly lower values of myo‐inositol/creatine in the precentral (p = 0.006), postcentral (p< 0.001), and precuneus (p = 0.006) regions.

Conclusions

We observed an increase in choline/creatine in anorexics, possibly reflecting increased cell turnover; a decrease in macromolecules, which was particularly low in the cingulate and precuneus the former being known to be altered in eating disorders; and a decrease in N‐acetyl aspartate/creatine considered as a marker of neuronal density and function.

Ventromedial prefrontal cortex/anterior cingulate cortex Glx, glutamate, and GABA levels in medication-free major depressive disorder

Glutamate (Glu) and gamma-aminobutyric acid (GABA) are implicated in the pathophysiology of major depressive disorder (MDD). GABA levels or GABAergic interneuron numbers are generally low in MDD, potentially disinhibiting Glu release. It is unclear whether Glu release or turnover is increased in depression. Conversely, a meta-analysis of prefrontal proton magnetic resonance spectroscopy (¹H MRS) studies in MDD finds low Glx (combination of glutamate and glutamine) in medicated MDD. We hypothesize that elevated Glx or Glu may be a marker of more severe, untreated MDD. We examined ventromedial prefrontal cortex/anterior cingulate cortex (vmPFC/ACC) Glx and glutamate levels using ¹H MRS in 34 medication-free, symptomatic, chronically ill MDD patients and 32 healthy volunteers, and GABA levels in a subsample. Elevated Glx and Glu were observed in MDD compared with healthy volunteers, with the highest levels seen in males with MDD. vmPFC/ACC GABA was low in MDD. Higher Glx levels correlated with more severe depression and lower GABA. MDD severity and diagnosis were both linked to higher Glx in vmPFC/ACC. Low GABA in a subset of these patients is consistent with our hypothesized model of low GABA leading to glutamate disinhibition in MDD. This finding and model are consistent with our previously reported findings that the NMDAR-antagonist antidepressant effect is proportional to the reduction of vmPFC/ACC Glx or Glu levels.

Effects of Inositol Hexaphosphate and Myo-Inositol Administration in Breast Cancer Patients during Adjuvant Chemotherapy

Background: Treatment of breast cancer (BC) includes locoregional and systemic therapies depending on tumor and patient’s characteristics. Inositol hexaphosphate (IP6) is known as a strong antioxidant agent, able to improve local (i.e., breast region) side effects, functional status and quality-of-life. We investigated some potential beneficial effects, including hematological and local, of the combined therapy with oral myo-inositol administration and topical IP6 application in patients undergoing surgery for BC and eligible to adjuvant chemotherapy. Methods: We considered BC patients randomly assigned to the Inositol Group (oral myo-inositol + IP6 local application for the entire neoadjuvant treatment period) and to the Control Group (standard of care). The EORTC QLQ-BR23 and QLQ-C30 questionnaires were administered to both groups and blood parameters were assessed as per clinical routine practice at baseline (before starting adjuvant chemotherapy), T1 (after the first two doses of epirubicin-cyclophosphamide regimen), T2 (at the end of epirubicin-cyclophosphamide regimen), T3 (after the first six doses of paclitaxel regimen), and T4 (at the end of the paclitaxel treatment). Results: A total of 36 BC patients were considered, 18 in the Inositol Group and 18 in the Control Group. The Inositol Group showed a lower decrease in red blood cells, hemoglobin levels and white blood cells with respect to controls (p ≤ 0.02), as well as amelioration in scores related to breast and arm local symptoms (p ≤ 0.02), body image (p = 0.04) and quality-of-life related symptoms (p ≤ 0.04). Conclusions: In our cohort of BC patients, a combined treatment with oral myo-inositol + IP6 local application was able to improve local symptoms and quality-of-life related symptoms which represent clinically relevant aspects associated with patient’s prognosis.

Inositols Depletion and Resistance: Principal Mechanisms and Therapeutic Strategies

Inositols are natural molecules involved in several biochemical and metabolic functions in different organs and tissues. The term "inositols" refers to five natural stereoisomers, among which myo-Inositol (myo-Ins) is the most abundant one. Several mechanisms contribute to regulate cellular and tissue homeostasis of myo-Ins levels, including its endogenous synthesis and catabolism, transmembrane transport, intestinal adsorption and renal excretion. Alterations in these mechanisms can lead to a reduction of inositols levels, exposing patient to several pathological conditions, such as Polycystic Ovary Syndrome (PCOS), hypothyroidism, hormonal and metabolic imbalances, like weight gain, hyperinsulinemia, dyslipidemia, and metabolic syndrome. Indeed, myo-Ins is involved in different physiological processes as a key player in signal pathways, including reproductive, hormonal, and metabolic modulation. Genetic mutations in genes codifying for proteins of myo-Ins synthesis and transport, competitive processes with structurally similar molecules, and the administration of specific drugs that cause a central depletion of myo-Ins as a therapeutic outcome, can lead to a reduction of inositols levels. A deeper knowledge of the main mechanisms involved in cellular inositols depletion may add new insights for developing tailored therapeutic approaches and shaping the dosages and the route of administration, with the aim to develop efficacious and safe approaches counteracting inositols depletion-induced pathological events.

Can Molecular Biology Propose Reliable Biomarkers for Diagnosing Major Depression?

BACKGROUND

Modern medicine has provided considerable knowledge of the pathophysiology of mental disorders at the body, systemic, organ and neurochemical levels of the biological organization of the body. Modern clinical diagnostics of depression have some problems, that is why psychiatric society makes use of diagnostics and taxonomy of different types of depression by implemention of modern molecular biomarkers in diagnostic procedures. But up to now, there are no reliable biomarkers of major depressive disorder (MDD) and other types of depression.

OBJECTIVE

The purpose of this review is to find fundamentals in pathological mechanisms of depression, which could be a basis for development of molecular and genetic biomarkers, being the most feasible for clinical use.

METHOD

This review summarizes the published data using PubMed, Science Direct, Google Scholar and Scopus.

RESULTS

In this review, we summarized and discussed findings in molecular biology, genetics, neuroplasticity, neurotransmitters, and neuroimaging that could increase our understanding of the biological foundations of depression and show new directions for the development of reliable biomarkers. We did not find any molecular and genetic biomarker approved for the clinic. But the Genome-Wide Association Study method promises some progress in the development of biomarkers based on SNP in the future. Epigenetic factors also are a promising target for biomarkers. We have found some differences in the etiology of different types of atypical and melancholic depression. This knowledge could be the basis for development of biomarkers for clinical practice in diagnosis, prognosis and selection of treatment.

CONCLUSION

Depression is not a monoetiological disease. Many pathological mechanisms are involved in depression, thus up to now, there is no approved and reliable biomarker for diagnosis, prognosis and correction of treatment of depression. The structural and functional complexity of the brain, the lack of invasive technology, poor correlations between genetic and clinical manifestation of depression, imperfect psychiatric classification and taxonomy of subtypes of disease are the main causes of this situation. One of the possible ways to come over this situation can be to pay attention to the trigger mechanism of disease and its subtypes. Researchers and clinicians should focus their efforts on searching the trigger mechanism of depression and different types of it . HPA axis can be a candidate for such trigger in depression caused by stress, because it influences the main branches of disease: neuroinflammation, activity of biogenic amines, oxidative and nitrosative stress, epigenetic factors, metabolomics, etc. But before we shall find any trigger mechanism, we need to create complex biomarkers reflecting genetic, epigenetic, metabolomics and other pathological changes in different types of depression. Recently the most encouraging results have been obtained from genetics and neuroimaging. Continuing research in these areas should be forced by using computational, statistical and systems biology approaches, which can allow to obtain more knowledge about the neurobiology of depression. In order to obtain clinically useful tests, search for biomarkers should use appropriate research methodologies with increasing samples and identifying more homogeneous groups of depressed patients.

Repeated fluoxetine treatment induces transient and long-term astrocytic plasticity in the medial prefrontal cortex of normal adult rats

Fluoxetine (Flx)-induced neuronal plasticity plays an important role in the effective treatment of depression and mood disorders. It is less understood whether repeated Flx treatment induces astrocytic plasticity that outlasts the presence of the drug in the body. We showed previously that Flx-induced neuronal plasticity in the medial prefrontal cortex (mPFC) persisted up to 20 days after the treatment. In this study, adult rats were subjected to a 15-day repeated Flx treatment at a daily dose of 20 mg/kg body weight. Astrocytic metabolites and markers were assessed in the mPFC at day 1 (d1) and day 20 (d20) after the treatment. Significant transient reductions in the concentrations of astrocytic metabolites taurine and myo-inositol and the expressions of glial fibrillary acidic protein (GFAP) and aquaporin-4 (AQP4) were observed in the mPFC of Flx-treated rats at d1, which recovered to the control levels at d20. Further, Flx treatment resulted in long-lasting changes in Kir4.1 expression in the mPFC, which remained downregulated at d20. The expression of 5-HT_1A receptor in the mPFC of Flx-treated rats was downregulated at d1 but became upregulated at d20. In summary, repeated Flx treatment induces both transient and long-term astrocytic plasticity in the mPFC of adult rats. The changes observed at d1 are consistent with disturbed water homeostasis and astrocytic de-maturation in the mPFC. The persistent changes in the expressions of Kir4.1 and 5-HT_1A at d20, presumably of the astrocytic origin, might have contributed to the long-term neurotrophic effects of repeated Flx treatment in the mPFC.

Immunological Disturbances and Neuroimaging Findings in Major Depressive Disorder (MDD) and Alcohol Use Disorder (AUD) Comorbid Patients

Mood disorders and Major Depressive Disorder, in particular, appear to be some of the most common psychiatric disorders with a high rate of comorbidity most frequently of anxiety or substance abuse disorders (alcohol use disorder). In both cases - MDD and AUD, a number of immunological disturbances are observed, such as chronic mild inflammation response, increased level of cytokines, hypercortisolaemia, which lead to specific changes in brain neurotransmitter functions. Some of the contemporary brain imaging techniques are functional magnetic resonance imaging (fMRI) and magnetic spectroscopy which are most commonly used to assess the brain metabolism and functional connectivity changes such as altered responses to emotional stimuli in MDD or overactivation of ventromedial prefrontal areas during delayed and underactivation of dorsolateral prefrontal regions during impulsive reward decisions in AUD and dysfunction of gamma-aminobutyric acid (GABA) and/or glutamate neurotransmitter systems, low NAA and myo-Inositol in both MDD and AUD.

Current Methods of Magnetic Resonance for Noninvasive Assessment of Molecular Aspects of Pathoetiology in Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disease with expanding axonal and neuronal degeneration in the central nervous system leading to motoric dysfunctions, psychical disability, and cognitive impairment during MS progression. The exact cascade of pathological processes (inflammation, demyelination, excitotoxicity, diffuse neuro-axonal degeneration, oxidative and metabolic stress, etc.) causing MS onset is still not fully understood, although several accompanying biomarkers are particularly suitable for the detection of early subclinical changes. Magnetic resonance (MR) methods are generally considered to be the most sensitive diagnostic tools. Their advantages include their noninvasive nature and their ability to image tissue in vivo. In particular, MR spectroscopy (proton 1H and phosphorus 31P MRS) is a powerful analytical tool for the detection and analysis of biomedically relevant metabolites, amino acids, and bioelements, and thus for providing information about neuro-axonal degradation, demyelination, reactive gliosis, mitochondrial and neurotransmitter failure, cellular energetic and membrane alternation, and the imbalance of magnesium homeostasis in specific tissues. Furthermore, the MR relaxometry-based detection of accumulated biogenic iron in the brain tissue is useful in disease evaluation. The early description and understanding of the developing pathological process might be critical for establishing clinically effective MS-modifying therapies.

The Biomedical Uses of Inositols: A Nutraceutical Approach to Metabolic Dysfunction in Aging and Neurodegenerative Diseases

Inositols are sugar-like compounds that are widely distributed in nature and are a part of membrane molecules, participating as second messengers in several cell-signaling processes. Isolation and characterization of inositol phosphoglycans containing myo- or d-chiro-inositol have been milestones for understanding the physiological regulation of insulin signaling. Other functions of inositols have been derived from the existence of multiple stereoisomers, which may confer antioxidant properties. In the brain, fluctuation of inositols in extracellular and intracellular compartments regulates neuronal and glial activity. Myo-inositol imbalance is observed in psychiatric diseases and its use shows efficacy for treatment of depression, anxiety, and compulsive disorders. Epi- and scyllo-inositol isomers are capable of stabilizing non-toxic forms of β-amyloid proteins, which are characteristic of Alzheimer’s disease and cognitive dementia in Down’s syndrome, both associated with brain insulin resistance. However, uncertainties of the intrinsic mechanisms of inositols regarding their biology are still unsolved. This work presents a critical review of inositol actions on insulin signaling, oxidative stress, and endothelial dysfunction, and its potential for either preventing or delaying cognitive impairment in aging and neurodegenerative diseases. The biomedical uses of inositols may represent a paradigm in the industrial approach perspective, which has generated growing interest for two decades, accompanied by clinical trials for Alzheimer’s disease.

Microbial and metabolomic profiles in correlation with depression and anxiety co-morbidities in diarrhoea-predominant IBS patients

BACKGROUND

Psychological co-morbidities in irritable bowel syndrome (IBS) have been widely recognized, whereas less is known regarding the role of gut microbial and host metabolic changes in clinical and psychological symptoms in IBS.

RESULTS

A total of 70 diarrhoea-predominant IBS (IBS-D) patients and 46 healthy controls were enrolled in this study. Stool and urine samples were collected from both groups for 16S rRNA gene sequencing and metabolomic analysis. The results showed that fecal microbiota in IBS-D featured depleted Faecalibacterium (adjusted P = 0.034), Eubacterium rectale group (adjusted P = 0.048), Subdoligranulum (adjusted P = 0.041) and increased Prevotella (adjusted P = 0.041). O-ureido-L-serine, 3,4-dihydroxybenzenesulfonic acid and (R)-2-Hydroxyglutarate demonstrated lower urinary concentrations in IBS-D patients. We further built correlation matrices between gut microbe abundance, differentiated metabolite quantities and clinical parameters. Dialister manifested negative association with IBS severity (r = - 0.285, P = 0.017), anxiety (r = - 0.347, P = 0.003) and depression level (r = - 0.308, P = 0.010). Roseburia was negatively associated with IBS severity (r = - 0.298, P = 0.012). Twenty metabolites correlated with anxiety or depression levels, including 3,4-dihydroxymandelaldehyde with SAS (r = - 0.383, P = 0.001), 1-methylxanthine with SDS (r = - 0.347, P = 0.004) and 1D-chiro-inositol with SAS (r = - 0.336, P = 0.005). In analysis of microbe-metabolite relationship, 3,4-dihydroxymandelaldehyde and 1-methylxanthine were negatively correlated with relative abundance of Clostridiumsensu stricto.

CONCLUSIONS

Our findings demonstrated altered microbial and metabolomic profiles associated with clinically and psychological symptoms in IBS-D patients, which may provide insights for further investigations.

Neuroimaging insights into the link between depression and Insomnia: A systematic review

BACKGROUND

Insomnia is a common symptom of Major Depressive Disorder (MDD) and genome-wide association studies pointed to their strong genetic association. Although the prevalence of insomnia symptoms in MDD is noticeable and evidence supports their strong bidirectional association, the number of available neuroimaging findings on patients of MDD with insomnia symptoms is limited. However, such neuroimaging studies could verily improve our understanding of their shared pathophysiology and advance corresponding theories.

METHODS

Based on the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guideline, we have conducted a literature search using PubMed, EMBASE, and Scopus databases and systematically explored 640 studies using various neuroimaging modalities in MDD patients with different degrees of insomnia symptoms.

RESULTS

Despite inconsistencies, current findings from eight studies suggested structural and functional disturbances in several brain regions including the amygdala, prefrontal cortex and anterior cingulate cortex and insula. The aberrant functional connectivity within and between the main hubs of the salience and default mode networks could potentially yield new insights into the link between MDD and insomnia, which needs further assessment.

LIMITATIONS

The number of studies reviewed herein is limited. The applied methods for assessing structural and functional neural mechanisms of insomnia and depression were variable.

CONCLUSION

Neuroimaging methods demonstrated the overlapping underlying neural mechanisms between MDD and insomnia. Future studies may facilitate better understanding of their pathophysiology to allow development of specific treatment.

Myo-Inositol and Its Derivatives: Their Emerging Role in the Treatment of Human Diseases

Myo-inositol has been established as an important growth-promoting factor of mammalian cells and animals. The role of myo-inositol as a lipotropic factor has been proven, in addition to its involvement as co-factors of enzymes and as messenger molecules in signal transduction. Myo-inositol deficiency leads to intestinal lipodystrophy in animals and "inositol-less death" in some fungi. Of late, diverse uses of myo-inositol and its derivatives have been discovered in medicinal research. These compounds are used in the treatment of a variety of ailments from diabetes to cancer, and continued research in this direction promises a new future in therapeutics. In different diseases, inositols implement different strategies for therapeutic actions such as tissue specific increase or decrease in inositol products, production of inositol phosphoglycans (IPGs), conversion of myo-inositol (MI) to D-chiro-inositol (DCI), modulation of signal transduction, regulation of reactive oxygen species (ROS) production, etc. Though inositol pharmacology is a relatively lesser-known field, recent years of research has generated a critical mass of information on the subject. This review aims to summarize our current understanding on the role of inositol derivatives in ameliorating the symptoms of different diseases.

Possible relation between consumption of different food groups and depression

BACKGROUND

Diverse studies have investigated the relationship between diet and depression. In fact some cross-sectional studies suggested that a healthy diet reduced the risk for depression. The main objective of this study was to assess the relationship of consumption of different food groups with depression. The food groups were selected based on their content of substances that were precursors to neurotransmitters (tryptophan or inositol) or their effect on oxidative stress.

METHODS

This observational retrospective study compared the diets of individuals who were with depressive symptoms (Beck Depression Inventory Questionnaire [BDI] ≥ 10; 53 women, 23 men, age 38+/- 11) and with no depressive levels (BDI < 10; 33 women, 23 men, age 41+/- 13). Dietary data were collected from a questionnaire that asked about consumption of legumes, nuts, whole-grain foods, fruits and vegetables, chocolate, and sweet foods and refined sugars.

RESULTS

Depressed individuals consumed significantly lower amounts of legumes, fruits, and vegetables, but higher amounts of sweets and refined sugars (p < 0.05 for all comparisons). After statistical adjustment for age and sex, the consumption of no legumes (adjusted odds ratio [aOR] = 2.60, 95% confidence interval [CI] = 1.19-5.67), low consumption of fruits and vegetables (aOR = 2.69, 95% CI = 1.18-6.13), and high consumption of sweet foods and refined sugars (aOR = 1.91, 95% CI = 1.23-2.99) were significantly associated with depression. The two groups had no significant differences in the consumption of chocolate.

DISCUSSION

The results indicate significant relationships of the consumption of certain foods with depression, although the study design precludes any conclusions regarding causality. Further studies are necessary to determine the causal relationships of the consumption of specific foods with depression, and of depression with the consumption of specific foods.

CONCLUSION

In spite of the limitations, we find that individuals without depression consumed more legumes, fruits, and vegetables, but fewer sweets and pastries than those with depression.

Glutamatergic neurometabolite levels in major depressive disorder: a systematic review and meta-analysis of proton magnetic resonance spectroscopy studies

Alterations in glutamatergic neurotransmission are implicated in the pathophysiology of depression, and the glutamatergic system represents a treatment target for depression. To summarize the nature of glutamatergic alterations in patients with depression, we conducted a meta-analysis of proton magnetic resonance (¹H-MRS) spectroscopy studies examining levels of glutamate. We used the search terms: depress* AND (MRS OR "magnetic resonance spectroscopy"). The search was performed with MEDLINE, Embase, and PsycINFO. The inclusion criteria were ¹H-MRS studies comparing levels of glutamate + glutamine (Glx), glutamate, or glutamine between patients with depression and healthy controls. Standardized mean differences (SMD) were calculated to assess group differences in the levels of glutamatergic neurometabolites. Forty-nine studies met the eligibility criteria, which included 1180 patients and 1066 healthy controls. There were significant decreases in Glx within the medial frontal cortex (SMD = -0.38; 95% CI, -0.69 to -0.07) in patients with depression compared with controls. Subanalyses revealed that there was a significant decrease in Glx in the medial frontal cortex in medicated patients with depression (SMD = -0.50; 95% CI, -0.80 to -0.20), but not in unmedicated patients (SMD = -0.27; 95% CI, -0.76 to 0.21) compared with controls. Overall, decreased levels of glutamatergic metabolites in the medial frontal cortex are linked with the pathophysiology of depression. These findings are in line with the hypothesis that depression may be associated with abnormal glutamatergic neurotransmission.