Potential roles of zinc in the pathophysiology and treatment of major depressive disorder

Gender-related alterations of serum trace elements and neurometabolism in the anterior cingulate cortex of patients with major depressive disorder

BACKGROUND

It is widely known that sex differences have a significant impact on patients with major depressive disorder (MDD). This study aims to evaluate the sex-related connection between serum trace elements and changes in neurometabolism in the anterior cingulate cortex (ACC) of MDD patients.

METHODS

109 untreated MDD patients and 59 healthy controls underwent proton magnetic resonance spectroscopy (1H-MRS) under resting conditions. We measured metabolic ratios in the ACC from both sides. Additionally, venous blood samples were taken from all participants to detect calcium (Ca), phosphorus, magnesium (Mg), copper (Cu), ceruloplasmin (CER), zinc (Zn), and iron (Fe) levels. We performed association and interaction analyses to explore the connections between the disease and gender.

RESULTS

In individuals with MDD, the Cu/Zn ratio increased, while the levels of Mg, CER, Zn and Fe decreased. Male MDD patients had lower Cu levels, while female patients had an increased Cu/Zn ratio. We observed significant gender differences in Cu, CER and the Cu/Zn ratio in MDD. Male patients showed a reduced N-acetyl aspartate (NAA)/phosphocreatine + creatine (PCr + Cr) ratio in the left ACC. The NAA/PCr + Cr ratio decreased in the right ACC in patients with MDD. In the left ACC of male MDD patients, the Cu/Zn ratio was inversely related to the NAA/PCr + Cr ratio, and Fe levels were negatively associated with the GPC + PC/PCr + Cr ratio.

CONCLUSIONS

Our findings highlight gender-specific changes in Cu homeostasis among male MDD patients. The Cu/Zn ratio and Fe levels in male MDD patients were significantly linked to neurometabolic alterations in the ACC.

Cellular neurobiology of hyperforin

Hyperforin is a phloroglucinol derivative isolated from the medicinal plant Hypericum perforatum (St John's wort, SJW). This lipophilic biomolecule displays antibacterial, pro-apoptotic, antiproliferative, and anti-inflammatory activities. In addition, in vitro and in vivo data showed that hyperforin is a promising molecule with potential applications in neurology and psychiatry. For instance, hyperforin possesses antidepressant properties, impairs the uptake of neurotransmitters, and stimulates the brain derived neurotrophic factor (BDNF)/TrkB neurotrophic signaling pathway, the adult hippocampal neurogenesis, and the brain homeostasis of zinc. In fact, hyperforin is a multi-target biomolecule with a complex neuropharmacological profile. However, one prominent pharmacological feature of hyperforin is its ability to influence the homeostasis of cations such as Ca2+ , Na+ , Zn2+ , and H+ . So far, the pathophysiological relevance of these actions is currently unknown. The main objective of the present work is to provide an overview of the cellular neurobiology of hyperforin, with a special focus on its effects on neuronal membranes and the movement of cations.

A review on linking stress, depression, and insulin resistance via low-grade chronic inflammation

Stress is a disturbance in homeostasis caused by psychological, physiological, or environmental factors. Prolonged reactions to chronic stress can be detrimental, resulting in various metabolic abnormalities, referred to as metabolic syndrome (MS). There is a reciprocal increased risk between MS and major depressive disorder. Recent studies established an association between inflammation and insulin signaling in type 2 diabetes mellitus with depression. In the present review, we discuss chronic low-grade inflammation, pathways of insulin resistance, and brain glucose metabolism in the context of neuroinflammation and depression. Specific attention is given to psychotropic drugs such as bupropion, mirtazapine, and nefazodone, anti-inflammatory drugs like Celecoxib (COX-2 inhibitor), Etanercept, adalimumab, IL-4Ra antagonist, Anti-IL- 17A antibody (Ixekizumab) and lifestyle modifications including exercise, dietary changes, and sleep hygiene. These therapeutic solutions offer potential in treating depression by targeting metabolic conditions like insulin resistance and inflammatory pathways. The article further explains the significance of a nutrition and antioxidants-rich diet, emphasizing the role of omega-3 fatty acids, vitamin D, zinc, and polyphenols, to improve immunity and activate anti-inflammatory signaling pathways.

Trace Elements Levels in Major Depressive Disorder-Evaluation of Potential Threats and Possible Therapeutic Approaches

The multifactorial etiology of major depressive disorder (MDD) includes biological, environmental, genetic, and psychological aspects. Recently, there has been an increasing interest in metallomic studies in psychiatry, aiming to evaluate the role of chosen trace elements in the MDD etiology as well as the progression of symptoms. This narrative review aims to summarize the available literature on the relationship between the concentration of chosen elements in the serum of patients with MDD and the onset and progression of this psychiatric condition. The authors reviewed PubMed, Web of Science, and Scopus databases searching for elements that had been investigated so far and further evaluated them in this paper. Ultimately, 15 elements were evaluated, namely, zinc, magnesium, selenium, iron, copper, aluminium, cadmium, lead, mercury, arsenic, calcium, manganese, chromium, nickel, and phosphorus. The association between metallomic studies and psychiatry has been developing dynamically recently. According to the results of current research, metallomics might act as a potential screening tool for patients with MDD while at the same time providing an assessment of the severity of symptoms. Either deficiencies or excessive amounts of chosen elements might be associated with the progression of depressive symptoms or even the onset of the disease among people predisposed to MDD.

Key Nutrients for Optimal Blood Glucose Control and Mental Health in Individuals with Diabetes: A Review of the Evidence

Diabetes is associated with an increased risk of mental disorders, including depression, anxiety, and cognitive decline. Mental disorders can also contribute to the development of diabetes through various mechanisms including increased stress, poor self-care behaviors, and adverse effects on glucose metabolism. Consequently, individuals suffering from either of these conditions frequently experience comorbidity with the other. Nutrition plays an important role in both diabetes and mental health disorders including depression and anxiety. Deficiencies in specific nutrients such as omega-3 fatty acids, vitamin D, B vitamins, zinc, chromium, magnesium, and selenium have been implicated in the pathogenesis of both diabetes and mental disorders. While the impact of nutrition on the progression and control of diabetes and mental disorders is broadly acknowledged, there is a notable knowledge gap concerning the implications of distinct nutrients in preventing and mitigating symptoms of both conditions when they coexist. The aim of this study was to examine the role of nutrition in improving glucose homeostasis and promoting mental well-being among individuals with diabetes. Further, we evaluated the preventive or delaying effects of key nutrients on the simultaneous manifestation of these conditions when one of them is present. Our findings indicated that the use of personalized dietary interventions and targeted nutrient supplementation can improve metabolic and mental health outcomes in patients with type 2 diabetes.

Association between serum zinc levels and suicidal ideation in US adults: A population-based cross-sectional study

BACKGROUND

Evidence suggests that the homeostatic disruption of zinc, copper, and selenium might contribute to the pathophysiology of mental disorders. However, the specific relationship between the serum levels of these trace elements with suicidal ideation remains poorly understood. This study aimed to investigated the association among suicidal ideation on serum levels of zinc, copper, and selenium.

METHODS

The cross-sectional study was conducted using data from a nationally representative sample of the National Health and Nutrition Examination Survey (NHANES) 2011-2016. Suicidal ideation was assessed using Item #9 of the Patient Health Questionnaire-9 Items. Multivariate regression models and restricted cubic splines were performed and E-value was calculated.

RESULTS

A total of 4561 participants aged 20 years and older were analyzed, of whom 4.08 % had suicidal ideation. The serum zinc levels were lower in the suicidal ideation group than in the non-suicidal ideation group (P = 0.021). In Crude Model, the serum zinc levels were associated with a higher suicidal ideation risk in the second quartile compared with the highest quartile [odds ratio (OR) = 2.63; 95 % confidence interval (CI): 1.53-4.53]. The association persisted (OR = 2.35; 95 % CI: 1.20-4.58) after full adjustment, with E-value 2.44. A nonlinear relationship was observed between serum zinc levels and suicidal ideation (P = 0.028). No relationship was observed between suicidal ideation and serum copper or selenium levels (all P > 0.05).

CONCLUSIONS

Decreased serum zinc levels may increase susceptibility to suicidal ideation. Future studies are needed to validate the findings of this study.

Zinc and Central Nervous System Disorders

Zinc (Zn²⁺) is the second most abundant necessary trace element in the human body, exerting a critical role in many physiological processes such as cellular proliferation, transcription, apoptosis, growth, immunity, and wound healing. It is an essential catalyst ion for many enzymes and transcription factors. The maintenance of Zn²⁺ homeostasis is essential for the central nervous system, in which Zn²⁺ is abundantly distributed and accumulates in presynaptic vesicles. Synaptic Zn²⁺ is necessary for neural transmission, playing a pivotal role in neurogenesis, cognition, memory, and learning. Emerging data suggest that disruption of Zn²⁺ homeostasis is associated with several central nervous system disorders including Alzheimer's disease, depression, Parkinson's disease, multiple sclerosis, schizophrenia, epilepsy, and traumatic brain injury. Here, we reviewed the correlation between Zn²⁺ and these central nervous system disorders. The potential mechanisms were also included. We hope that this review can provide new clues for the prevention and treatment of nervous system disorders.

The Important Role of Zinc in Neurological Diseases

Zinc is one of the most abundant metal ions in the central nervous system (CNS), where it plays a crucial role in both physiological and pathological brain functions. Zinc promotes antioxidant effects, neurogenesis, and immune system responses. From neonatal brain development to the preservation and control of adult brain function, zinc is a vital homeostatic component of the CNS. Molecularly, zinc regulates gene expression with transcription factors and activates dozens of enzymes involved in neuronal metabolism. During development and in adulthood, zinc acts as a regulator of synaptic activity and neuronal plasticity at the cellular level. There are several neurological diseases that may be affected by changes in zinc status, and these include stroke, neurodegenerative diseases, traumatic brain injuries, and depression. Accordingly, zinc deficiency may result in declines in cognition and learning and an increase in oxidative stress, while zinc accumulation may lead to neurotoxicity and neuronal cell death. In this review, we explore the mechanisms of brain zinc balance, the role of zinc in neurological diseases, and strategies affecting zinc for the prevention and treatment of these diseases.

Chronic Stress and Oxidative Stress as Common Factors of the Pathogenesis of Depression and Alzheimer's Disease: The Role of Antioxidants in Prevention and Treatment

There is a growing body of scientific research showing the link between depression and dementia in Alzheimer’s disease (AD). The chronic stress contributes to the formation of oxidative stress in the parts of the brain involved in the development of depression and AD. The scientific literature reports the significant role of antioxidants, which are highly effective in treating these diseases. In this review, we have summarized the relationship between chronic stress, oxidative stress, and the changes in the brain they cause occurring in the brain. Among all the compounds showing antioxidant properties, the most promising results in AD treatment were observed for Vitamin E, coenzyme Q10 (CoQ10), melatonin, polyphenols, curcumin, and selenium. In case of depression treatment, the greatest potential was observed in curcumin, zinc, selenium, vitamin E, and saffron.

Impact of Supplementation and Nutritional Interventions on Pathogenic Processes of Mood Disorders: A Review of the Evidence

This narrative review was conducted using searches of the PubMed/Medline and Google Scholar databases from inception to November 2019. Clinical trials and relevant articles were identified by cross-referencing major depressive disorder (and/or variants) with the following terms: folate, homocysteine, S-adenosylmethionine (SAMe), L-acetylcarnitine, alpha-lipoic acid, N-acetylcysteine, L-tryptophan, zinc, magnesium, vitamin D, omega-3 fatty acids, coenzyme Q10, and inositol. Manual reviews of references were also performed using article reference lists. Abnormal levels of folate, homocysteine, and SAMe have been shown to be associated with a higher risk of depression. Numerous studies have demonstrated antidepressant activity with L-methylfolate and SAMe supplementation in individuals with depression. Additionally, the amino acids L-acetylcarnitine, alpha-lipoic acid, N-acetylcysteine, and L-tryptophan have been implicated in the development of depression and shown to exert antidepressant effects. Other agents with evidence for improving depressive symptoms include zinc, magnesium, omega-3 fatty acids, and coenzyme Q10. Potential biases and differences in study designs within and amongst the studies and reviews selected may confound results. Augmentation of antidepressant medications with various supplements targeting nutritional and physiological factors can potentiate antidepressant effects. Medical foods, particularly L-methylfolate, and other supplements may play a role in managing depression in patients with inadequate response to antidepressant therapies.

Factors associated with symptoms of depression among pregnant women with gestational diabetes mellitus in Japan

The objective of this study was to explore the factors associated symptoms of depression among pregnant women with gestational diabetes mellitus (GDM) in Japan. This cross-sectional study was conducted at a hospital in Toyota, Japan, from January 2015 to June 2016. Pregnant women who visited the hospital and were diagnosed with GDM in the second trimester were enrolled. We analyzed depression symptoms using the Centers for Epidemiological Studies Depression Scale (CES-D) and considered related factors of depression symptoms, such as dietary intake and daily walking. Dietary intake during the past month was assessed using a brief self-administered diet history questionnaire, and daily walking was assessed using an accelerometer. The prevalence rate for GDM was 8.8%, and 25 pregnant women with GDM were analyzed. The CES-D was not significantly correlated with pre-pregnancy BMI, postprandial plasma glucose, hemoglobin A1c, and the number of steps walked. In contrast, a significant negative correlation was observed between the CES-D score and intake of fish with bones, simmered fish, pickles, green leaves, mushrooms, and green tea. Furthermore, a significant positive correlation was found between Coke^® and CES-D scores. For nutrient intake, a significant negative correlation was found between the CES-D score and vitamin K, folate, and β-carotene levels. The present study suggests that depression symptoms among pregnant women with GDM in the second trimester may be associated with diet.

Associations of different types of dairy intakes with depressive symptoms in adults

BACKGROUND

Current evidence on the associations between different types of milk products and depressive symptoms is few and controversial, and there has been no study focusing on different types of milk (whole-fat, low-fat, and skim). This study aimed to appraise their associations.

METHODS

This cross-sectional study included adults (N=21,924) from the National Health and Nutrition Examination Survey 2007-2016. Patient Health Questionnaire was used to evaluate depressive symptoms. Logistic regression model was implemented to assess the association of dairy consumption with depressive symptoms.

RESULTS

After multivariate adjustment, compared to non-consumers, the odds ratios (95% confidence intervals) of depressive symptoms for intake < 175.38 g/d and 175.38 to < 321.56 g/d of skim milk were 0.48 (0.27-0.85) and 0.46 (0.29-0.75), and 0.70 (0.55-0.88) for intake < 81.00 g/d of milk desserts, while 1.61 (1.05-2.46), 1.70 (1.15-2.50) and 1.55 (1.11-2.16) for intake < 129.63 g/d, 129.63 to < 289.75 g/d and ≥ 289.75 g/d of whole milk, respectively. These associations remained significant in stratified analyses by gender and age. Additionally, yogurt was negatively associated with depressive symptoms in both females and the age group (≥ 60 years). Low-fat milk was inversely associated with depressive symptoms for both males and the age group (≥ 60 years). Moderate creams intake was negatively associated with depressive symptoms in males.

LIMITATIONS

It was difficult to infer causality for a cross-sectional study.

CONCLUSIONS

Intakes of skim milk and moderate milk desserts were negatively associated with depressive symptoms, while whole milk was positively associated with depressive symptoms among adults.

Succeeding in deactivating: associations of hair zinc levels with functional and structural neural mechanisms

Zinc is a biologically essential element and involved in a wide range of cellular processes. Here, we investigated the associations of zinc levels in hair with brain activity during the n-back working memory task using functional magnetic resonance imaging, fractional anisotropy (FA) of diffusion tensor imaging, and cognitive differences in a study cohort of 924 healthy young adults. Our findings showed that greater hair zinc levels were associated with lower brain activity during working memory in extensive areas in the default mode network (i.e., greater task-induced deactivation) as well as greater FA in white matter areas near the hippocampus and posterior limbs of the internal capsule. These findings advance previous non-neuroimaging findings of zinc's associations with excitability, excitability-associated disorders, and myelination.

Anorexia nervosa, zinc deficiency and the glutamate system: The ketamine option

Anorexia nervosa (AN) is a severe, biological brain disorder with significant medical risks and a tenacious development over time. Unfortunately, few treatments show efficacy in people with AN although numerous therapies including pharmacological have been explored. Zinc deficiency has been implicated in AN and zinc is important in a large range of processes in the brain. In particular, it is an allosteric modulator of NMDA receptors - the maintenance of zinc levels within a normal, narrow range is essential for glutamatergic functioning. Chronic zinc deficiency increases neuronal stores of calcium and reduces direct modulation of NMDA receptors which collectively lead to overactivation and upregulation of NMDA receptors. This may facilitate pathologically high levels of glutamate, calcium influx and subsequent excitotoxicity, which can disrupt synaptogenesis and synaptic plasticity. While studies of zinc supplementation in AN have shown some promise, the efficacy of this treatment is limited. This may be due to AN illness chronicity and the significant changes already made, as well as a reduced potency of zinc to inhibit NMDA receptors in a pathological state. Thus, we propose that the safe (at low doses) yet more potent NMDA receptor antagonist, ketamine, may act to normalise a perturbed glutamatergic system and increase synaptogenesis in the short term. This 'kickstart' via ketamine could then allow zinc supplementation and other forms of treatment to enhance recovery in AN.

Rare variants and biological pathways identified in treatment-refractory depression

Individuals diagnosed with major depressive disorder not responding to at least two adequate treatments are defined as treatment-refractory major depressive disorder (TR-MDD). Some TR-MDD patients have altered metabolic phenotypes that may be pharmacologically reversed. The characterization of these phenotypes and their underlying etiologies is paramount, particularly their genetic components. In this study, TR-MDD patients (n = 124) were recruited and metabolites were quantified in their cerebrospinal fluid (CSF) and peripheral blood. Three sub-categories of deficiencies were examined, namely 5-methyltetrahydrofolte (in CSF; n = 13), tetrahydrobiopterin (in CSF; n = 11), and abnormal acylcarnitine profiles (in peripheral blood; n = 8). Whole exome sequencing was performed on genomic DNA from the entire TR-MDD cohort and exonic variant allele frequencies for cases were compared to a control cohort (1:5 matching on ancestry). Low frequency, damaging alleles were identified and used for in silico pathway analyses. Three association signals for TR-MDD approached genome-wide significance on chromosomes 22, 7, and 3. Three risk-associated variants from a prior depression study were replicated. Relevant biological pathways were identified that contained an enrichment of rare, damaging variants in central nervous system (CNS)-specific pathways, including neurotransmitter receptors, potassium channels, and synapse transmission. Some TR-MDD patients had rare variants in genes that were previously associated with other psychiatric disorders, psychiatric endophenotypes, CNS structural defects, and CNS-related cellular and molecular functions. Exome analysis of metabolically phenotyped TR-MDD patients has identified potentially functional gene pathways and low frequency, deleterious gene variants for further investigation. Further studies in larger cohorts of biochemically phenotyped TR-MDD patients are desirable to extend and confirm these findings.

Targeting Inflammatory-Mitochondrial Response in Major Depression: Current Evidence and Further Challenges

The prevalence of psychiatric disorders has increased in recent years. Among existing mental disorders, major depressive disorder (MDD) has emerged as one of the leading causes of disability worldwide, affecting individuals throughout their lives. Currently, MDD affects 15% of adults in the Americas. Over the past 50 years, pharmacotherapy, psychotherapy, and brain stimulation have been used to treat MDD. The most common approach is still pharmacotherapy; however, studies show that about 40% of patients are refractory to existing treatments. Although the monoamine hypothesis has been widely accepted as a molecular mechanism to explain the etiology of depression, its relationship with other biochemical phenomena remains only partially understood. This is the case of the link between MDD and inflammation, mitochondrial dysfunction, and oxidative stress. Studies have found that depressive patients usually exhibit altered inflammatory markers, mitochondrial membrane depolarization, oxidized mitochondrial DNA, and thus high levels of both central and peripheral reactive oxygen species (ROS). The effect of antidepressants on these events remains unclear. Nevertheless, the effects of ROS on the brain are well known, including lipid peroxidation of neuronal membranes, accumulation of peroxidation products in neurons, protein and DNA damage, reduced antioxidant defenses, apoptosis induction, and neuroinflammation. Antioxidants such as ascorbic acid, tocopherols, and coenzyme Q have shown promise in some depressive patients, but without consensus on their efficacy. Hence, this paper provides a review of MDD and its association with inflammation, mitochondrial dysfunction, and oxidative stress and is aimed at thoroughly discussing the putative links between these events, which may contribute to the design and development of new therapeutic approaches for patients.

Lowered zinc and copper levels in drug-naïve patients with major depression: Effects of antidepressants, ketoprofen and immune activation

Objectives: The aim of the present work is to examine the effects of treatment with sertraline with and without ketoprofen on serum levels of zinc and copper in association with immune-inflammatory biomarkers in drug-naïve major depressed patients.Methods: We measured serum zinc and copper, interleukin (IL)-1β, IL-4, IL-6, IL-18, interferon-γ, and transforming growth factor-β1 in 40 controls and 133 depressed patients. The clinical efficacy of the treatment was measured using the Beck Depression Inventory-II (BDI-II) at baseline and 8 weeks later.Results: We found significantly reduced serum zinc and copper in association with upregulation of all cytokines, indicating activation of the immune-inflammatory responses system (IRS) and the compensatory immune regulatory system (CIRS). Treatment with sertraline significantly increased zinc and decreased copper. During treatment, there was a significant inverse association between serum zinc and immune activation. The improvement in the BDI-II during treatment was significantly associated with increments in serum zinc coupled with attenuation of the IRS/CIRS.Conclusions: Lower zinc is a hallmark of depression, while increments in serum zinc and attenuation of the immune-inflammatory response during treatment appear to play a role in the clinical efficacy of sertraline.

Vitamins and Minerals for Energy, Fatigue and Cognition: A Narrative Review of the Biochemical and Clinical Evidence

Vitamins and minerals are essential to humans as they play essential roles in a variety of basic metabolic pathways that support fundamental cellular functions. In particular, their involvement in energy-yielding metabolism, DNA synthesis, oxygen transport, and neuronal functions makes them critical for brain and muscular function. These, in turn, translate into effects on cognitive and psychological processes, including mental and physical fatigue. This review is focused on B vitamins (B1, B2, B3, B5, B6, B8, B9 and B12), vitamin C, iron, magnesium and zinc, which have recognized roles in these outcomes. It summarizes the biochemical bases and actions of these micronutrients at both the molecular and cellular levels and connects them with cognitive and psychological symptoms, as well as manifestations of fatigue that may occur when status or supplies of these micronutrients are not adequate.

Intracellular labile zinc is a determinant of vulnerability of cultured astrocytes to oxidative stress

Recently, we found that treatment of cultured mouse astrocytes of ddY-strain mice (ddY-astrocytes) with 400 μM H₂O₂ for 24 h increased the intracellular labile zinc level without cell toxicity. In contrast, 170 μM H₂O₂ for 12 h is reported to kill mouse astrocytes obtained from C57BL/6-strain mice (C57BL/6-astrocytes) with an increase in intracellular labile zinc. To clarify this discrepancy, we compared the intracellular zinc levels and cell toxicity in H₂O₂-treated ddY- and C57BL/6-astrocytes. Exposure of C57BL/6-astrocytes to 170 or 400 μM H₂O₂ for 12 h dose-dependently decreased the cell viability and administration of plasma membrane-permeable zinc chelator TPEN prevented the 170 μM H₂O₂-induced astrocyte death, while neither concentration of H₂O₂ killed ddY-astrocytes. The intracellular zinc level in H₂O₂-treated C57BL/6-astrocytes was higher than that in H₂O₂-treated ddY-astrocytes, and this increase was suppressed by TPEN. There was no apparent difference in the expression levels of zinc transporters ZIPs and ZnTs between the two types of astrocytes, while expression of zinc releasable channel TRPM7 was found on the plasma membrane in ddY-astrocytes, but not in C57BL/6-astrocytes, although the total cellular expression levels were almost the same. In addition, a TRPM7 blocker, 2-aminoethoxydiphenyl borate, increased the intracellular zinc level in H₂O₂-treated ddY-, but not C57BL/6-astrocytes. Collectively, it is suggested that vulnerability of astrocytes to oxidative stress depends on an increased level of intracellular labile zinc, and TRPM7 localized on the plasma membrane contributes, at least in part, to ameliorate the cell injury by decreasing the zinc level.

Modulation of Gpr39, a G-protein coupled receptor associated with alcohol use in non-human primates, curbs ethanol intake in mice

Alcohol use disorder (AUD) is a chronic condition with devastating health and socioeconomic effects. Still, pharmacotherapies to treat AUD are scarce. In a prior study aimed at identifying novel AUD therapeutic targets, we investigated the DNA methylome of the nucleus accumbens core (NAcc) of rhesus macaques after chronic alcohol use. The G-protein coupled receptor 39 (GPR39) gene was hypermethylated and its expression downregulated in heavy alcohol drinking macaques. GPR39 encodes a Zn2+-binding metabotropic receptor known to modulate excitatory and inhibitory neurotransmission, the balance of which is altered in AUD. These prior findings suggest that a GPR39 agonist would reduce alcohol intake. Using a drinking-in-the-dark two bottle choice (DID-2BC) model, we showed that an acute 7.5 mg/kg dose of the GPR39 agonist, TC-G 1008, reduced ethanol intake in mice without affecting total fluid intake, locomotor activity or saccharin preference. Furthermore, repeated doses of the agonist prevented ethanol escalation in an intermittent access 2BC paradigm (IA-2BC). This effect was reversible, as ethanol escalation followed agonist "wash out". As observed during the DID-2BC study, a subsequent acute agonist challenge during the IA-2BC procedure reduced ethanol intake by ~47%. Finally, Gpr39 activation was associated with changes in Gpr39 and Bdnf expression, and in glutamate release in the NAcc. Together, our findings suggest that GPR39 is a promising target for the development of prevention and treatment therapies for AUD.

Zinc inhibited LPS-induced inflammatory responses by upregulating A20 expression in microglia BV2 cells

BACKGROUND

Our previous studies have proved that zinc supplement effectively alleviate depression symptoms in mice, but the mechanisms are still uncertain. Neuroinflammation is considered as an important aspect in pathogenesis of depression. To elucidate the role of zinc on neuroinflammation, in this study, we investigated effects of zinc on lipopolysaccharide (LPS)-induced inflammation in BV2 microglia cells, a kind of innate immune cells in central nervous system.

METHODS

BV2 cells were treated by 100 ng/ml LPS to induce inflammatory responses and the effects of zinc sulfate (ZnSO₄) addition on LPS-induced inflammation were observed. Besides, through culturing HT-22 hippocampus cells by using medium transferred from zinc-intervened BV2 cells, the protective roles of zinc on hippocampus cells were identified.

RESULTS

LPS treatment up-regulated expressions of CD11b, inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX2), tumor necrosis factor α (TNFα) and interleukin-6 (IL-6) and level of reactive oxygen species (ROS). Meaningfully, zinc was capable of blocking ROS generation and reducing expressions of the above inflammatory cytokines at both 10 μM and 30 μM. In addition, it was proved that zinc intervention to BV2 cells could increase the viabilities of hippocampal HT-22 cells cultured by medium of BV2 cells. Furthermore, the zinc-finger protein A20, an anti-inflammation factor, was increased by zinc supplement, while levels of p65, p-IκB and p-p65 were significantly decreased.

LIMITATIONS

More compelling proofs were needed to ensure roles of A20 in anti-inflammatory effects of zinc.

CONCLUSIONS

The present results suggested that zinc inhibits inflammatory responses mediated by microglia cells via upregulation of zinc-finger A20. It was proposed that this anti-inflammatory action might be underlying mechanism of previously observed anti-depressive effects of zinc.

Long-lasting antidepressant-like activity of the GPR39 zinc receptor agonist TC-G 1008

BACKGROUND

The discovery of the zinc-sensing receptor, has provided new possibilities for explaining the neurobiology of zinc. Recent studies indicate that the GPR39 zinc receptor may play an important role in the pathogenesis of depression as well as in the antidepressant mechanism of action.

METHODS

In this study we evaluated the time-course of the antidepressant response of the GPR39 agonist (TC-G 1008), imipramine, ZnCl₂ and MK-801 in the forced swim test in mice 30 min, 3 h, 6 h and 24 h after acute drug administration as well as after 14-day treatment. Zinc level was measured in serum of mice. BDNF protein level was evaluated in hippocampus following both acute and chronic TC-G 1008 treatment.

RESULTS

A single administration of the GPR39 agonist caused an antidepressant-like effect lasting up to 24 h following the injection, which is longer than the effect of imipramine, ZnCl₂ and MK-801. Chronic treatment with these compounds caused a decrease in immobility time in the FST. Serum zinc concentrations showed an increased level following chronic ZnCl₂ administration, but not following administration of TC-G 1008, imipramine or MK-801. We also observed some tendencies for increased BDNF following acute TC-G 1008 treatment.

LIMITATIONS

TC-G 1008 is new drug designed to study GPR39 therefore additional pharmacodynamic and pharmacokinetic properties in preclinical studies are required.

CONCLUSION

This study shows for the first time the long-lasting antidepressant effect of the GPR39 agonist in comparison with imipramine, ZnCl2 and MK-801. Our findings suggest that GPR39 should be considered as a target in efforts to develop new antidepressant drugs.

Relationship of Dietary and Serum Zinc with Depression Score in Iranian Adolescent Girls

Zinc deficiency, which is common among Iranian populations, is believed to play a crucial role in the onset and progression of mood disorders such as depression in different stages of life. We have therefore investigated the relationship between serum/dietary zinc status and depression scores among adolescent girls living in northeastern Iran. Serum zinc was measured by flame atomic absorption (Varian AA240FS) and the mean zinc intake was assessed using 3-day food record. A validated Persian version of the Beck Depression Inventory (BDI) was used to determine the severity of depressive symptoms for all subjects. Data were analyzed using SPSS 18 software. There was a statistically significant correlation between dietary zinc intake and serum zinc concentration (r = 0.117, p = 0.018). Dietary intake of zinc (7.04 ± 4.28 mg/day) was significantly lower among subjects with mild to severe depression symptoms than those with no or minimal depression symptoms (8.06 ± 3.03 mg/day). Dietary zinc intake was inversely correlated with depression score (r = 0.133, p = 0.008). However, there was no significant difference in serum zinc concentrations among individuals with no or minimal and mild to severe depression symptoms (p = 0.5). Dietary zinc intake, but not serum zinc concentration, was inversely associated with depression symptoms. Therefore, controlled clinical trials are needed to determine the efficacy of zinc supplementation in the treatment of depression disorders.

Crosstalk between zinc and free fatty acids in plasma

In mammalian blood plasma, serum albumin acts as a transport protein for free fatty acids, other lipids and hydrophobic molecules including neurodegenerative peptides, and essential metal ions such as zinc to allow their systemic distribution. Importantly, binding of these chemically extremely diverse entities is not independent, but linked allosterically. One particularly intriguing allosteric link exists between free fatty acid and zinc binding. Albumin thus mediates crosstalk between energy status/metabolism and organismal zinc handling. In recognition of the fact that even small changes in extracellular zinc concentration and speciation modulate the function of many cell types, the albumin-mediated impact of free fatty acid concentration on zinc distribution may be significant for both normal physiological processes including energy metabolism, insulin activity, heparin neutralisation, blood coagulation, and zinc signalling, and a range of disease states, including metabolic syndrome, cardiovascular disease, myocardial ischemia, diabetes, and thrombosis.

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Serum albumin binds and transports both free fatty acids and Zn²⁺ ions

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Elevated plasma free fatty acids impair Zn²⁺ binding by albumin through an allosteric mechanism

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The resulting changes in plasma zinc speciation are thought to impact blood coagulation and may promote thrombosis

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Increased free Zn²⁺ may lead to enhanced zinc export from plasma and dysregulation of zinc homeostasis in multiple tissues

Modulation of P2X7 purinergic receptor activity by extracellular Zn2+ in cultured mouse hippocampal astroglia

The P2X7R protein, a P2 type purinergic receptor functioning as a non-selective cation channel, is expressed in different cell types of the central nervous system in several regions of the brain. The activation of the P2X7R protein by ATP modulates excitatory neurotransmission and contributes to microglial activation, apoptosis and neuron-glia communication. Zinc is an essential micronutrient that is highly concentrated in the synaptic vesicles of glutamatergic hippocampal neurons where free zinc ions released into the synaptic cleft alter glutamatergic signal transmission. Changes in both P2X7R-mediated signaling and brain zinc homeostasis have been implicated in the pathogenesis of mood disorders. Here, we tested the hypothesis that extracellular zinc regulates P2X7R activity in the hippocampus. We observed that P2X7R is expressed in both neurons and glial cells in primary mouse hippocampal neuron-glia culture. Propidium iodide (PI) uptake through large pores formed by pannexins and P2X7R was dose-dependently inhibited by extracellular zinc ions. Calcium influx mediated by P2X7R in glial cells was also reduced by free zinc ions. Interestingly, no calcium influx was detected in response to ATP or 3'-O-(4-Benzoyl) benzoyl ATP (BzATP) in neurons despite the expression of P2X7R at the plasma membrane. Our results show that free zinc ions can modulate hippocampal glial purinergic signaling, and changes in the activity of P2X7R may contribute to the development of depression-like behaviors associated with zinc deficiency.

Zinc in schizophrenia: A meta-analysis

OBJECTIVE

The role of zinc homeostasis in various psychopathologies is an emerging area of interest. Zinc is strongly implicated in depressive disorders but is inadequately studied in schizophrenia, despite growing evidence of abnormal zinc transporters associated with schizophrenia. A meta-analysis of serum zinc concentrations in persons with schizophrenia was conducted to address this gap.

METHOD

PubMed and Embase were searched for all articles published through February 2018 that reported serum zinc concentrations in individuals with schizophrenia and in comparison subjects. A random-effects meta-analysis was carried out to compare mean serum zinc concentrations between the groups in terms of the weighted mean difference.

RESULTS

The current meta-analysis combined 10 studies, including a total of 658 schizophrenia patients and 1008 controls. Serum zinc concentration was significantly lower in individuals with schizophrenia than controls (12.81 μg/dl (1.96 μmol/l), t = -2.59, 95% CI: -22.50 to -3.12, p < 0.05). The reduction in zinc levels was more pronounced among inpatients and newly diagnosed, drug-naïve patients.

CONCLUSIONS

The current meta-analysis supports a disturbance of zinc homeostasis in individuals with schizophrenia compared to healthy controls, although the relationship between reduced serum zinc levels and psychotic symptoms remains unknown. Altered serum zinc might be linked to defective transporters and/or inflammation that impact the brain's glutamatergic system.

Association of total zinc, iron, copper and selenium intakes with depression in the US adults

BACKGROUND

The aim of present study was to examine the associations of total zinc, iron, copper and selenium intakes from diet and supplements with depression.

METHODS

Cross-sectional study used data from the National Health and Nutrition Examination Survey (NHANES) 2009-2014 in the present study. Logistic regression models and restricted cubic spline models were applied to examine the associations of total zinc, iron, copper and selenium intakes with depression.

RESULTS

A total of 14834 adults aged 18 years or older (7399 men and 7435 women) were included in the present study. Total zinc, iron, copper and selenium intakes were inversely associated with depression in unadjusted model and age- and gender-adjusted model. The multivariate adjusted odds ratios (ORs) with 95% confidence intervals (CIs) of depression were 0.68 (0.49-0.94) and 0.46 (0.32-0.67) for the highest versus lowest quartile of copper and selenium intakes, respectively. The inverse associations of depression were statistically significant for the quartile 3 versus lowest quartile of total zinc (OR: 0.70; 95% CI: 0.49-0.99) and iron intake (OR: 0.66 95% CI: 0.50-0.87). Compared to those below the RDA (Recommended Dietary Allowance), participants who met the RDA for zinc (OR: 0.74; 95% CI: 0.56-0.99), copper (OR: 0.68; 95% CI: 0.56-0.82) and selenium (OR: 0.52; 95% CI: 0.39, 0.71) had significantly lower odds of depression.

LIMITATIONS

This was a cross-sectional study, limiting causal inferences. Assessment of depression was based on a self- report scale.

CONCLUSION

Total zinc, iron, copper and selenium intakes may be inversely associated with depression.

Serum zinc levels in acute psychiatric patients: A case series

Zinc dysregulation is linked to neuropsychiatric disorders and a beneficial response to zinc supplementation has been demonstrated for depression. In this case series, we examined serum zinc levels with respect to clinical factors among 20 acutely ill psychiatric cases admitted to a large urban public hospital. The results showed frank clinical zinc insufficiency in a quarter of the subjects. Group-wise analyses showed a significant association between reduced serum zinc and diagnosis of depression, and reduced serum zinc in those with aggressive, assaultive, or violent behaviors. By contrast, relatively elevated zinc levels were observed in a subset of psychotic cases on antipsychotics and mood stabilizers who had no mood symptoms. In summary, clinical zinc insufficiency was common in these acutely admitted psychiatric cases. Zinc supplementation may ameliorate symptoms in certain cases and should be considered in treatment planning. A separate patient group had elevated zinc levels, which could conceivably be pathogenic. Larger studies are needed to confirm and extend this pilot data.

Associations Between Serum Zinc Levels and Mental Health: Findings from the 2010 Korean National Health and Nutrition Examination Survey

Mental health problems are a major public health issue worldwide, and zinc may be associated with psychiatric symptoms, but such associations have not been investigated extensively. This study was conducted to evaluate the relationship between serum zinc levels and mental health problems in Korean adults. We used data from the Korean National Health and Nutrition Examination Survey V-1, a cross-sectional survey of Korean civilians. Data from 1748 subjects were analyzed. Serum zinc levels did not differ significantly according to psychiatric symptoms including sleep duration, stress, depressed mood, suicidal ideation, and whether respondents sought psychiatric consultation. The frequencies and odds ratios of psychiatric symptoms according to serum zinc tertiles were not significantly associated after adjusting for age, smoking, alcohol consumption, physical activity, body mass index, total body fat, and renal function and for daily fat, carbohydrate, and protein intake. Serum zinc levels may not be associated with psychiatric symptoms in Korean adults without psychiatric disorders.

Biometal Dyshomeostasis and Toxic Metal Accumulations in the Development of Alzheimer's Disease

Biometal dyshomeostasis and toxic metal accumulation are common features in many neurodegenerative disorders, including Alzheimer’s disease (AD), Parkinson’s disease, and Huntington’s disease. The neurotoxic effects of metal imbalance are generally associated with reduced enzymatic activities, elevated protein aggregation and oxidative stress in the central nervous system, in which a cascade of events lead to cell death and neurodegeneration. Although the links between biometal imbalance and neurodegenerative disorders remain elusive, a major class of endogenous proteins involved in metal transport has been receiving increasing attention over recent decades. The abnormal expression of these proteins has been linked to biometal imbalance and to the pathogenesis of AD. Here, we present a brief overview of the physiological roles of biometals including iron, zinc, copper, manganese, magnesium and calcium, and provide a detailed description of their transporters and their synergistic involvement in the development of AD. In addition, we also review the published data relating to neurotoxic metals in AD, including aluminum, lead, cadmium, and mercury.

Dietary zinc and iron intake and risk of depression: A meta-analysis

The associations between dietary zinc and iron intake and risk of depression remain controversial. Thus, we carried out a meta-analysis to evaluate these associations. A systematic search was performed in PubMed, Embase, Web of Science, Chinese National Knowledge Infrastructure (CNKI) and Wanfang databases for relevant studies up to January 2017. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using a random effects model. A total of 9 studies for dietary zinc intake and 3 studies for dietary iron intake were finally included in present meta-analysis. The pooled RRs with 95% CIs of depression for the highest versus lowest dietary zinc and iron intake were 0.67 (95% CI: 0.58-0.76) and 0.57 (95% CI: 0.34-0.95), respectively. In subgroup analysis by study design, the inverse association between dietary zinc intake and risk of depression remained significant in the cohort studies and cross-sectional studies. The pooled RRs (95% CIs) for depression did not substantially change in the influence analysis and subgroup analysis by adjustment for body mass index (BMI). The present meta-analysis indicates inverse associations between dietary zinc and iron intake and risk of depression.

Allosteric Inhibition of Serotonin 5-HT7 Receptors by Zinc Ions

The allosteric regulation of G protein-coupled receptors (GPCRs) is a well-known phenomenon, but there are only a few examples of allosteric modulation within the metabotropic serotonergic receptor family. Recently, we described zinc non-competitive interactions toward agonist binding at serotonin 5-HT_1A receptors, in which biphasic effects, involving potentiation at sub-micromolar concentrations (10 μM) and inhibition at sub-millimolar concentrations (500 μM) of Zn²⁺ in radioligand binding assays, were consistent with both the agonist and antagonist-like effects of zinc ions observed in in vivo studies. Here, we showed new data demonstrating zinc allosteric inhibition of both agonist and antagonist binding at human recombinant 5-HT₇ receptors stably expressed in HEK293 cells as observed by radioligand binding studies as well as zinc neutral antagonism displayed by the concentration of 10 μM in the functional LANCE assay. The allosteric nature of the effect of Zn on 5-HT₇ receptors was confirmed (1) in saturation studies in which zinc inhibited the binding of potent orthosteric 5-HT₇ receptor radioligands, the agonist [³H]5-CT, and the two antagonists [³H]SB-269970 and [³H]mesulergine, showing ceiling effect and differences in the magnitude of negative cooperativity (α = 0.15, 0.06, and 0.25, respectively); (2) in competition experiments in which 500 μM of zinc inhibited all radioligand displacements by non-labeled orthosteric ligands (5-CT, SB-269970, and clozapine), and the most significant reduction in affinity was observed for the 5-CT agonist (4.9–16.7-fold) compared with both antagonists (1.4–3.9-fold); and (3) in kinetic experiments in which 500 μM zinc increased the dissociation rate constants for [³H]5-CT and [³H]mesulergine but not for [³H]SB-269970. Additionally, in the functional LANCE test using the constitutively active HEK293 cell line expressing the 5-HT₇ receptor, 10 μM zinc had features of neutral antagonism and increased the EC₅₀ value of the 5-CT agonist by a factor of 3.2. Overall, these results showed that zinc can act as a negative allosteric inhibitor of 5-HT₇ receptors. Given that the inhibiting effects of low concentrations of zinc in the functional assay represent the most likely direction of zinc activity under physiological conditions, among numerous zinc-regulated proteins, the 5-HT₇ receptor can be considered a serotonergic target for zinc modulation in the CNS.

Alterations of Hair and Nail Content of Selected Trace Elements in Nonoccupationally Exposed Patients with Chronic Depression from Different Geographical Regions

The aim of this study was to determine if altered levels of selected trace elements manifest themselves during chronic depression. To identify elements strongly associated with chronic depression, relationships between the elemental contents of hair and nails and the interelement correlations were checked. Inductively coupled plasma mass spectrometry and ion chromatography were used to evaluate the contents of Zn, Cu, Co, Pb, Mn, and Fe in hair and nail samples from a total of 415 subjects (295 patients and 120 healthy volunteers). The study included logistic regression models to predict the probability of chronic depression. To investigate possible intercorrelations among the studied elements, the scaled principal component analysis was used. The research has revealed differences in TE levels in the group of depressed men and women in comparison to the healthy subjects. Statistically significant differences in both hair and nails contents of several elements were observed. Our study also provides strong evidence that the intermediary metabolism of certain elements is age- and gender-dependent. Zn, Mn, Pb, and Fe contents in hair/nails seem to be strongly associated with chronic depression. We found no statistically significant residence-related differences in the contents of studied elements in nonoccupationally exposed patients and healthy subjects.

The serum zinc concentration as a potential biological marker in patients with major depressive disorder

Despite many clinical trials assessing the role of zinc in major depressive disorder (MDD), the conclusions still remain ambiguous. The aim of the present clinical study was to determine and comparison the zinc concentration in the blood of MDD patients (active stage or remission) and healthy volunteers (controls), as well as to discuss its potential clinical usefulness as a biomarker of the disease. In this study 69 patients with current depressive episode, 45 patients in remission and 50 controls were enrolled. The zinc concentration was measured by electrothermal atomic absorption spectrometry (ET AAS). The obtained results revealed, that the zinc concentration in depressed phase were statistically lower than in the healthy volunteers [0.89 vs. 1.06 mg/L, respectively], while the zinc level in patients achieve remission was not significantly different from the controls [1.07 vs. 1.06 mg/L, respectively]. Additionally, among the patients achieve remission a significant differences in zinc concentration between group with and without presence of drug-resistance in the previous episode of depression were observed. Also, patients in remission demonstrated correlation between zinc level and the average number of depressive episodes in the last year. Serum zinc concentration was not dependent on atypical features of depression, presence of psychotic symptoms or melancholic syndrome, age, age of onset or duration of disease, number of episodes in the life time, duration of the episode/remission and severity of depression measured by the Hamilton Rating Scale for Depression (HDRS), and the Montgomery-Asberg Depression Rating Scale (MADRS). Concluding, our findings confirm the correlation between zinc deficit present in the depressive episode, and are consistent with the majority of previous studies. These results may also indicate that serum zinc concentration might be considered as a potential biological marker of MDD.

The level of the zinc homeostasis regulating proteins in the brain of rats subjected to olfactory bulbectomy model of depression

BACKGROUND

Zinc transporters (ZnTs) and metallothioneins (MT) are important in maintaining Zn homeostasis in the brain. The present study was designed to find out whether alterations in ZnTs and MTs are associated with the pathophysiology of depression and the mechanism of antidepressant action.

METHODS

Messenger RNA and proteins of ZnT1, ZnT3, ZnT4, ZnT5, ZnT6 and MT1/2 were measured in the prefrontal cortex (PFC) and hippocampus (Hp) of rats subjected to olfactory bulbectomy (OB) (a model of depression) and chronic amitriptyline (AMI) treatment by Real Time PCR and Western Blot/Immunohistochemistry (IHP).

RESULTS

Results in the OB rats showed: increases in the protein levels of ZnT1 in the PFC and Hp and MT1/2 in the PFC; a decrease in ZnT3 protein level in the PFC; no changes in ZnT4, ZnT5 and ZnT6 in the PFC and Hp. IHP labeling revealed increases in the optical densities of ZnT1-IR in the PFC and Hp and decreases in ZnT3 and ZnT4-IR in the PFC of OB rats. Although OB had no effects on gene expression of ZnTs, mRNAs for MT1/2 were increased. Chronic AMI treatment did not influence protein levels of ZnTs and MT1/2 in Sham and OB rats; however decreased mRNA levels of ZnT4 and ZnT5 in PFC and ZnT1, ZnT3, ZnT4 and ZnT6 in Hp of Sham rats and normalized OB induced increase in MT1/2 gene expression.

CONCLUSIONS

Changes in ZnTs and MT1/2 suggest altered cortical distribution of Zn in the OB model which further supports the hypothesis that Zn dyshomeostasis may be involved in the pathophysiology of depression.

Oxidative stress-induced increase of intracellular zinc in astrocytes decreases their functional expression of P2X7 receptors and engulfing activity

Exposure of astrocytes to oxidative stress induces an increase of intracellular labile zinc and a decrease of functional expression of P2X7 receptorviaits translocation from the plasma membrane to the cytosol by altering the expression profile of P2X7 receptor and its splice variants, leading to a decrease of their engulfing activity.

Negative correlation between CSF zinc level and anxiety in male Chinese subjects

Zinc is crucial for brain development and psychiatric regulation. In the present study, we investigated the relationship between cerebrospinal fluid (CSF) zinc level and anxiety in a group of male Chinese subjects. Results demonstrated that zinc levels had no considerable interindividual variations, ranging from 8.37 to 16.83µm. Correlation analyses revealed that CSF Zinc levels were positively correlated with education years (r=0.225, p=0.024) and negatively correlated with SAS scores (r=-0.287, p=0.004), but not associated with age or BMI. In conclusion, this present study suggests that CSF zinc level is associated with anxiety.

The Role of Elements in Anxiety

Elements (bioelements) are necessary factors required for the physiological function of organisms. They are critically involved in fundamental processes of life. Extra- and intracellular message and metabolic pathway factors as well as structural components include one or many elements in their functional structure. Recent years have seen an intensification in terms of knowledge gained about the roles of elements in anxiety disorders. In this chapter we present a review of the most important current data concerning the involvement of zinc, magnesium, copper, lithium, iron, and manganese, and their deficiency, in the pathophysiology and treatment of anxiety.

Zinc in the Glutamatergic Theory of Depression

Depression is a serious psychiatric illness that affects millions of people worldwide. Weeks of antidepressant therapy are required to relieve depressive symptoms, and new drugs are still being extensively researched. The latest studies have shown that in depression, there is an imbalance between the main excitatory (glutamatergic) and inhibitory (GABAergic) systems. Administration of antagonists of the glutamatergic system, including zinc, has shown an antidepressant effect in preclinical as well as clinical studies. Zinc inhibits the NMDA receptor via its binding site located on one of its subunits. This is thought to be the main mechanism explaining the antidepressant properties of zinc. In the present review, a link between zinc and the glutamatergic system is discussed in the context of depressive disorder.

Oxidative Stress Implications in the Affective Disorders: Main Biomarkers, Animal Models Relevance, Genetic Perspectives, and Antioxidant Approaches

The correlation between the affective disorders and the almost ubiquitous pathological oxidative stress can be described in a multifactorial way, as an important mechanism of central nervous system impairment. Whether the obvious changes which occur in oxidative balance of the affective disorders are a part of the constitutive mechanism or a collateral effect yet remains as an interesting question. However it is now clear that oxidative stress is a component of these disorders, being characterized by different aspects in a disease-dependent manner. Still, there are a lot of controversies regarding the relevance of the oxidative stress status in most of the affective disorders and despite the fact that most of the studies are showing that the affective disorders development can be correlated to increased oxidative levels, there are various studies stating that oxidative stress is not linked with the mood changing tendencies. Thus, in this minireview we decided to describe the way in which oxidative stress is involved in the affective disorders development, by focusing on the main oxidative stress markers that could be used mechanistically and therapeutically in these deficiencies, the genetic perspectives, some antioxidant approaches, and the relevance of some animal models studies in this context.

Serum zinc concentrations and depression in persons with Human Immunodeficiency Virus infection: The positive living with HIV (POLH) study

Low levels of serum zinc concentrations and depression are common in persons infected with Human Immunodeficiency Virus (HIV). Low levels of serum zinc concentrations may increase risk of depression in general population. However, research on the role of zinc in depression among HIV- infected person is limited. We assessed the association between serum zinc concentrations and depression in HIV-infected persons. A cross-sectional survey was conducted among 311 HIV-positive people (177 men and 134 women) aged 18-60 years residing in Kathmandu, Nepal. The atomic absorption method was used to measure serum zinc concentrations and the Beck Depression Inventory (BDI)-Ia method was used to measure depression, with cut off score 20 or higher consistent with clinically significant depression. Relationships were assessed using multiple linear and logistic regression analyses. Serum zinc concentrations were significantly inversely associated with depression in all participants and in men but not in women. Participants with the highest tertile of serum zinc concentrations had a significantly decreased risk of depression in men but not in women. Serum zinc concentrations were inversely associated with depressive symptoms scores in HIV-infected men. Further prospective studies are needed to confirm the role of zinc in depression among persons infected with HIV.

Mapping inflammation onto mood: Inflammatory mediators of anhedonia

Evidence supports inflammatory involvement in mood and cognitive symptoms across psychiatric, neurological and medical disorders; however, inflammation is not a sensitive or specific characteristic of these diagnoses. The National Institute of Mental Health Research Domain Criteria (RDoC) ask for a shift away from symptom-based diagnoses toward a transdiagnostic neurobiological focus in the study of brain illnesses. The RDoC matrix may provide a useful framework for integrating the effects of inflammation on brain function. Based on preclinical and clinical findings, relevant relationships span negative and positive valence systems, cognitive systems, systems for social processes and arousal/regulatory systems. As an exemplar, we consider the psychopathological domain of anhedonia, conceptualizing the relevance of inflammation (e.g., cellular immunity) and downstream processes (e.g., indoleamine 2,3-dioxygenase activation and oxidative inactivation of tetrahydrobiopterin) across RDoC units of analysis (e.g., catecholamine neurotransmitter molecules, nucleus accumbens medium spiny neuronal cells, dopaminergic mesolimbic and mesocortical reward circuits, animal paradigms, etc.). We discuss implications across illnesses affecting the brain, including infection, major depressive disorder, stroke, Alzheimer's disease and type 2 diabetes.

Involvement of glutamatergic neurotransmission in the antidepressant-like effect of zinc in the chronic unpredictable stress model of depression

Stress and excessive glutamatergic neurotransmission have been implicated in the pathophysiology of depression. Therefore, this study was aimed at investigating the influence of zinc on depressive-like behavior induced by chronic unpredictable stress (CUS), on alterations in glutamate-induced toxicity and immunocontent of proteins involved in the control of glutamatergic neurotransmission in the hippocampus of mice. Mice were subjected to CUS procedure for 14 days. From the 8th to the 14th day, mice received zinc chloride (ZnCl2) (10 mg/kg) or fluoxetine (10 mg/kg, positive control) once a day by oral route. CUS caused a depressive-like behavior evidenced by the increased immobility time in the tail suspension test (TST), which was prevented by treatment with ZnCl2 or fluoxetine. Ex vivo exposure of hippocampal slices to glutamate (10 mM) resulted in a significant decrease on cell viability; however, neither CUS procedure nor drug treatments altered this reduction. No alterations in the immunocontents of GLT-1 and GFAP or p-Akt were observed in any experimental group. The ratio of p-Akt/AKT was also not altered in any group. However, Akt immunocontent was increased in stressed mice and in animals treated with ZnCl2 (stressed or non-stressed mice) and EAAC1 immunocontent was increased in stressed mice treated with ZnCl2, fluoxetine or vehicle and in non-stressed mice treated with ZnCl2 and fluoxetine. These findings indicate a robust effect of zinc in reversing behavioral alteration induced by CUS in mice, through a possible modulation of the glutamatergic neurotransmission, extending literature data regarding the mechanisms underlying its antidepressant-like action.

A review of nutrient treatments for paediatric depression

Paediatric depression is estimated to affect 15-20% of youths prior to adulthood and is associated with significant social, educational and physical impairment. Current treatments comprise moderately efficacious psychological therapies and pharmaceutical antidepressants. However, nutritional therapies are also available and are regularly sought by people with depressive illnesses and parents of depressed youths. In this narrative review, studies examining the antidepressant effects of individual nutritional supplements in child and adolescent populations are appraised. Epidemiological studies examining the relationship between nutritional status and paediatric depression, or depressive symptoms are also reviewed. Nutrients covered in this article include: omega-3 polyunsaturated fatty acids, s-adenosylmethionine, vitamin C, vitamin D, zinc, iron and B-vitamins. Although several of these nutrients present as promising treatments for paediatric depression, there is a lack of high-quality studies examining the antidepressant effects of all the aforementioned ingredients. Before nutritional treatments are accepted as validated treatments for paediatric depression, further high-quality studies are required.

Higher Body Iron Is Associated with Greater Depression Symptoms among Young Adult Men but not Women: Observational Data from the Daily Life Study

Studies investigating possible associations between iron status and mood or depressive symptoms have reported inconsistent results. However, they have neither used body iron to measure iron status nor measured mood using daily measures. We investigated whether body iron was associated with depressive symptoms, daily mood, daily tiredness, difficulty concentrating, and stress in young adult women and men. Young adult (17–25 years) women (n = 562) and men (n = 323) completed the Center for Epidemiologic Studies Depression Scale, then reported negative and positive mood, and other states daily for 13 days. Non-fasting venous blood was collected to determine hemoglobin, serum ferritin and soluble transferrin receptor (to calculate body iron), C-reactive protein, and alpha-1-acid glycoprotein concentration. Regression models tested linear associations between body iron and the outcome variables, controlling for possible confounders. No associations were found between body iron and the outcome variables in women. However, higher body iron was associated with more depressive symptoms in men (3.4% more per body iron mg/kg; 95% confidence intervals (CI): 0.8%, 5.9%). In young adult women, body iron is unlikely to be associated with significant deficits in mood or depressive symptoms. However, higher body iron may be associated with more depressive symptoms in young adult men.