Bidirectional longitudinal associations of omega-3 polyunsaturated fatty acid plasma levels with depressive disorders

Central activation of the fatty acid sensor GPR120 suppresses microglia reactivity and alleviates sickness- and anxiety-like behaviors

G protein-coupled receptor 120 (GPR120, Ffar4) is a sensor for long-chain fatty acids including omega-3 polyunsaturated fatty acids (n-3 PUFAs) known for beneficial effects on inflammation, metabolism, and mood. GPR120 mediates the anti-inflammatory and insulin-sensitizing effects of n-3 PUFAs in peripheral tissues. The aim of this study was to determine the impact of GPR120 stimulation on microglial reactivity, neuroinflammation and sickness- and anxiety-like behaviors by acute proinflammatory insults. We found GPR120 mRNA to be enriched in  both murine and human microglia, and in situ hybridization revealed GPR120 expression in microglia of the nucleus accumbens (NAc) in mice. In a manner similar to or exceeding n-3 PUFAs, GPR120 agonism (Compound A, CpdA) strongly attenuated lipopolysaccharide (LPS)-induced proinflammatory marker expression in primary mouse microglia, including tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), and inhibited nuclear factor-ĸB translocation to the nucleus. Central administration of CpdA to adult mice blunted LPS-induced hypolocomotion and anxiety-like behavior and reduced TNF-α, IL-1β and IBA-1 (microglia marker) mRNA in the NAc, a brain region modulating anxiety and motivation and implicated in neuroinflammation-induced mood deficits. GPR120 agonist pre-treatment attenuated NAc microglia reactivity and alleviated sickness-like behaviors elicited by central injection TNF-α and IL-1β. These findings suggest that microglial GPR120 contributes to neuroimmune regulation and behavioral changes in response to acute infection and elevated brain cytokines. GPR120 may participate in the protective action of n-3 PUFAs at the neural and behavioral level and offers potential as treatment target for neuroinflammatory conditions.

The Effect of Very-Long-Chain n-3 Polyunsaturated Fatty Acids in the Central Nervous System and Their Potential Benefits for Treating Alcohol Use Disorder: Reviewing Pre-Clinical and Clinical Data

Alcohol use poses a significant global health concern, leading to serious physical and socioeconomic issues worldwide. The current treatment options for problematic alcohol consumption are limited, leading to the exploration of alternative approaches, such as nutraceuticals. One promising target is very-long-chain n-3 polyunsaturated fatty acids (VLC n-3 PUFAs). This review aims to compile the most relevant pre-clinical and clinical evidence on the effect of VLC n-3 PUFAs on alcohol use disorders and related outcomes. The findings suggest that VLC n-3 PUFAs may alleviate the physiological changes induced by alcohol consumption, including neuroinflammation and neurotransmitter dysregulation. Additionally, they can reduce withdrawal symptoms, improve mood, and reduce stress level, all of which are closely associated with problematic alcohol consumption. However, more research is required to fully understand the precise mechanisms by which VLC n-3 PUFAs exert their function. Furthermore, PUFAs should not be considered a standalone solution, but as a complement to other therapeutic approaches. Although preliminary evidence supports the potential therapeutic effect of VLC n-3 PUFAs on problematic alcohol consumption, additional research is needed to validate these findings and determine the optimal use of PUFAs as part of a comprehensive approach to the treatment of alcohol use disorders.

Personalized Medicine of Omega-3 Fatty Acids in Depression Treatment in Obese and Metabolically Dysregulated Patients

The co-occurrence of depression and obesity has become a significant public health concern worldwide. Recent studies have shown that metabolic dysfunction, which is commonly observed in obese individuals and is characterized by inflammation, insulin resistance, leptin resistance, and hypertension, is a critical risk factor for depression. This dysfunction may induce structural and functional changes in the brain, ultimately contributing to depression's development. Given that obesity and depression mutually increase each other's risk of development by 50-60%, there is a need for effective interventions that address both conditions. The comorbidity of depression with obesity and metabolic dysregulation is thought to be related to chronic low-grade inflammation, characterized by increased circulating levels of pro-inflammatory cytokines and C-reactive protein (CRP). As pharmacotherapy fails in at least 30-40% of cases to adequately treat major depressive disorder, a nutritional approach is emerging as a promising alternative. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) are a promising dietary intervention that can reduce inflammatory biomarkers, particularly in patients with high levels of inflammation, including pregnant women with gestational diabetes, patients with type 2 diabetes mellitus, and overweight individuals with major depressive disorder. Further efforts directed at implementing these strategies in clinical practice could contribute to improved outcomes in patients with depression, comorbid obesity, and/or metabolic dysregulation.

Protein posttranslational modifications in health and diseases: Functions, regulatory mechanisms, and therapeutic implications

Protein posttranslational modifications (PTMs) refer to the breaking or generation of covalent bonds on the backbones or amino acid side chains of proteins and expand the diversity of proteins, which provides the basis for the emergence of organismal complexity. To date, more than 650 types of protein modifications, such as the most well-known phosphorylation, ubiquitination, glycosylation, methylation, SUMOylation, short-chain and long-chain acylation modifications, redox modifications, and irreversible modifications, have been described, and the inventory is still increasing. By changing the protein conformation, localization, activity, stability, charges, and interactions with other biomolecules, PTMs ultimately alter the phenotypes and biological processes of cells. The homeostasis of protein modifications is important to human health. Abnormal PTMs may cause changes in protein properties and loss of protein functions, which are closely related to the occurrence and development of various diseases. In this review, we systematically introduce the characteristics, regulatory mechanisms, and functions of various PTMs in health and diseases. In addition, the therapeutic prospects in various diseases by targeting PTMs and associated regulatory enzymes are also summarized. This work will deepen the understanding of protein modifications in health and diseases and promote the discovery of diagnostic and prognostic markers and drug targets for diseases.

A Preliminary Comparison of Plasma Tryptophan Metabolites and Medium- and Long-Chain Fatty Acids in Adult Patients with Major Depressive Disorder and Schizophrenia

Background and Objectives: Disturbance of tryptophan (Trp) and fatty acid (FA) metabolism plays a role in the pathogenesis of psychiatric disorders. However, quantitative analysis and comparison of plasma Trp metabolites and medium- and long-chain fatty acids (MCFAs and LCFAs) in adult patients with major depressive disorder (MDD) and schizophrenia (SCH) are limited. Materials and Methods: Clinical symptoms were assessed and the level of Trp metabolites and MCFAs and LCFAs for plasma samples from patients with MDD (n = 24) or SCH (n = 22) and healthy controls (HC, n = 23) were obtained and analyzed. Results: We observed changes in Trp metabolites and MCFAs and LCFAs with MDD and SCH and found that Trp and its metabolites, such as N-formyl-kynurenine (NKY), 5-hydroxyindole-3-acetic acid (5-HIAA), and indole, as well as omega-3 polyunsaturated fatty acids (N3) and the ratio of N3 to omega-6 polyunsaturated fatty acids (N3: N6), decreased in both MDD and SCH patients. Meanwhile, levels of saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) decreased in SCH patients, and there was a significant difference in the composition of MCFAs and LCFAs between MDD and SCH patients. Moreover, the top 10 differential molecules could distinguish the two groups of diseases from HC and each other with high reliability. Conclusions: This study provides a further understanding of dysfunctional Trp and FA metabolism in adult patients with SCH or MDD and might develop combinatorial classifiers to distinguish between these disorders.

Omega-3 Polyunsaturated Fatty Acids Supplementation Alleviate Anxiety Rather Than Depressive Symptoms Among First-Diagnosed, Drug-Naïve Major Depressive Disorder Patients: A Randomized Clinical Trial

Background

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) augmentation of antidepressants has shown great potential in the prevention and treatment of major depressive disorders (MDD).

Objective

To investigate the effect of n-3 PUFAs plus venlafaxine in patients with first-diagnosed, drug-naïve depression.

Method

A total of 72 outpatients with first-diagnosed depression were recruited. The daily dose of 2.4 g/day n-3 PUFAs or placebo plus venlafaxine was used for over 12 weeks. The outcomes were assessed by the Hamilton depression scale (HAMD), Hamilton anxiety scale (HAMA), Beck depression inventory (BDI), and Self-rating anxiety scale (SAS).

Results

Both groups exhibited improvement on clinical characteristics at week 4 and week 12 compared with baseline. The rate of responders for anxiety in n-3 PUFAs group (44.44%) was significantly higher than that in placebo group (21.21%) at week 4 (χ² = 4.182, p = 0.041), while week 12 did not show a difference (χ² = 0.900, p = 0.343). The rate of responders for depression at both week 4 (χ² = 0.261, p = 0.609) and week 12 (χ² = 1.443, p = 0.230) showed no significant difference between two groups. Further analysis found that Childhood Trauma Questionnaire (CTQ) had positive correlation with HAMA (r = 0.301, p = 0.012), SAS (r = 0.246, p = 0.015), HAMD (r = 0.252, p = 0.038) and BDI (r = 0.233, p = 0.022) with Pearson correlation analysis. Social Support Rating Scale (SSRS) had negative correlation with SAS (r = -0.244, p = 0.015) and BDI (r = -0.365, p = 0.000).

Conclusion

This trial found that n-3 PUFAs supplementation in favor of venlafaxine alleviated the anxiety symptoms rather than depressive symptoms at the early stage of treatment (4 weeks) for first-diagnosed, drug-naïve depressed patients. However, the advantage disappeared in long-term treatment. Furthermore, childhood abuse and social support are closely related to the clinical and biological characteristics of depression. Both childhood trauma and lack of social support might be predictors of poor prognosis in depression.

Clinical Trial Registration

[clinicaltrials.gov], identifier [NCT03295708].

Possible antidepressant mechanisms of omega-3 polyunsaturated fatty acids acting on the central nervous system

Omega-3 polyunsaturated fatty acids (PUFAs) can play important roles in maintaining mental health and resistance to stress, and omega-3 PUFAs supplementation can display beneficial effects on both the prevention and treatment of depressive disorders. Although the underlying mechanisms are still unclear, accumulated evidence indicates that omega-3 PUFAs can exhibit pleiotropic effects on the neural structure and function. Thus, they play fundamental roles in brain activities involved in the mood regulation. Since depressive symptoms have been assumed to be of central origin, this review aims to summarize the recently published studies to identify the potential neurobiological mechanisms underlying the anti-depressant effects of omega-3 PUFAs. These include that of (1) anti-neuroinflammatory; (2) hypothalamus-pituitary-adrenal (HPA) axis; (3) anti-oxidative stress; (4) anti-neurodegeneration; (5) neuroplasticity and synaptic plasticity; and (6) modulation of neurotransmitter systems. Despite many lines of evidence have hinted that these mechanisms may co-exist and work in concert to produce anti-depressive effects, the potentially multiple sites of action of omega-3 PUFAs need to be fully established. We also discussed the limitations of current studies and suggest future directions for preclinical and translational research in this field.

Metabolomic profiles discriminating anxiety from depression

OBJECTIVE

Depression has been associated with metabolomic alterations. Depressive and anxiety disorders are often comorbid diagnoses and are suggested to share etiology. We investigated whether differential metabolomic alterations are present between anxiety and depressive disorders and which clinical characteristics of these disorders are related to metabolomic alterations.

METHODS

Data were from the Netherlands Study of Depression and Anxiety (NESDA), including individuals with current comorbid anxiety and depressive disorders (N = 531), only a current depression (N = 304), only a current anxiety disorder (N = 548), remitted depressive and/or anxiety disorders (N = 897), and healthy controls (N = 634). Forty metabolites from a proton nuclear magnetic resonance lipid-based metabolomics panel were analyzed. First, we examined differences in metabolites between disorder groups and healthy controls. Next, we assessed whether depression or anxiety clinical characteristics (severity and symptom duration) were associated with metabolites.

RESULTS

As compared to healthy controls, seven metabolomic alterations were found in the group with only depression, reflecting an inflammatory (glycoprotein acetyls; Cohen's d = 0.12, p = 0.002) and atherogenic-lipoprotein-related (e.g., apolipoprotein B: Cohen's d = 0.08, p = 0.03, and VLDL cholesterol: Cohen's d = 0.08, p = 0.04) profile. The comorbid group showed an attenuated but similar pattern of deviations. No metabolomic alterations were found in the group with only anxiety disorders. The majority of metabolites associated with depression diagnosis were also associated with depression severity; no associations were found with anxiety severity or disease duration.

CONCLUSION

While substantial clinical overlap exists between depressive and anxiety disorders, this study suggests that altered inflammatory and atherogenic-lipoprotein-related metabolomic profiles are uniquely associated with depression rather than anxiety disorders.

Exploring the therapeutic potential of omega-3 fatty acids in depression

Omega-3 fatty acids have been acknowledged for their number of holdings on an individual's health. Not only in physical valuation but also in managing psychiatric disorders, omega-3 fatty acids have been found to be a powerful formula. It is proclaimed that depressive patients suffer anomaly with the levels of omega-3 polyunsaturated fatty acids in the body, coupled with insignificant EPA and DHA. Enhancement in brain functioning, neuronal functions, and paying attention in interacting with the brain cells are some of the additional tasks, being performed by the supplementation of omega-3 fatty acids. The leading and primary source via dietary supplementation involves the involvement of fish and fish products. These are hypothesized to be the best and dominant source for omega-3 fatty acids. Consumption of omega-3 fatty acid is well safe, that physician highly favors intake of these supplements, remarkably in the case of pregnant women. However, treating this serious life-threatening mental disorder leads to many adverse effects when treated with antidepressants. The dose range includes 1g/d to 10g/d, which is to be incorporated by the patient. It is also tested that the combination of EPA and DHA is found to be more efficacious for a person in treating and preventing depressive symptoms. Some studies verify the supplementation of omega-3 fatty acids in diet was coequally productive and successful with minimal side effects when analyzed with antidepressants. Despite these facts, much research is still needed and presently in process for long-term safety and studying the role of omega-3 fatty acids in human health.