Role of zinc in the development and treatment of mood disorders

Low dietary or supplemental zinc is associated with depression symptoms among women, but not men, in a population-based epidemiological survey

BACKGROUND

Prior studies indicate that the biochemical alterations of depressive episodes result in decreased serum zinc concentrations. Given these findings, it is plausible that consistently low dietary zinc intakes contribute to depressive symptoms, yet epidemiological data are lacking. The authors tested the hypothesis that low zinc intake is associated with depressive symptoms using cross-sectional data from the population-based Boston Area Community Health survey (2002-2005).

METHODS

Dietary and supplement use data were collected by validated food frequency questionnaire. Current depressive symptoms were assessed by the abridged validated Center for Epidemiologic Studies Depression scale and analyzed using multivariate logistic regression, adjusting for sociodemographic, health and lifestyle characteristics.

RESULTS

Results showed an interaction (P=0.03) with gender, whereby zinc was associated with depressive symptoms in women (N=2163), but not men (N=1545). Women with low dietary or supplemental zinc intake were more likely to have depressive symptoms (e.g., dietary zinc quartile 1 vs. 4, OR=1.76, 95% CI: 1.26, 2.45; P-trend=0.004; supplemental zinc P-trend=0.03). Associations were stronger among women using antidepressant medications (e.g., total zinc OR=4.75, 95% CI: 1.98, 11.4; P-trend=0.0005).

LIMITATIONS

The cross-sectional, observational nature of the study leaves uncertain whether the observed associations represent actual causal relationships between zinc intake and depressive symptoms.

CONCLUSIONS

These findings suggest: (1) gender-specific pathophysiological mechanisms of depression, (2) inadequate dietary zinc intake contributes to depressive symptoms in women, and (3) supplemental zinc is a beneficial adjunct to antidepressant therapy in women. Additional research on both men and women is needed to verify these novel findings. If confirmed by other studies, the potential importance of adequate zinc intake is underscored by the recognized limitations of pharmacotherapy for depression.

Brain-Delivery of Zinc-Ions as Potential Treatment for Neurological Diseases: Mini Review

Homeostasis of metal ions such as Zn(2+) is essential for proper brain function. Moreover, the list of psychiatric and neurodegenerative disorders involving a dysregulation of brain Zn(2+)-levels is long and steadily growing, including Parkinson's and Alzheimer's disease as well as schizophrenia, attention deficit and hyperactivity disorder, depression, amyotrophic lateral sclerosis, Down's syndrome, multiple sclerosis, Wilson's disease and Pick's disease. Furthermore, alterations in Zn(2+)-levels are seen in transient forebrain ischemia, seizures, traumatic brain injury and alcoholism. Thus, the possibility of altering Zn(2+)-levels within the brain is emerging as a new target for the prevention and treatment of psychiatric and neurological diseases. Although the role of Zn(2+) in the brain has been extensively studied over the past decades, methods for controlled regulation and manipulation of Zn(2+) concentrations within the brain are still in their infancy. Since the use of dietary Zn(2+) supplementation and restriction has major limitations, new methods and alternative approaches are currently under investigation, such as the use of intracranial infusion of Zn(2+) chelators or nanoparticle technologies to elevate or decrease intracellular Zn(2+) levels. Therefore, this review briefly summarizes the role of Zn(2+) in psychiatric and neurodegenerative diseases and highlights key findings and impediments of brain Zn(2+)-level manipulation. Furthermore, some methods and compounds, such as metal ion chelation, redistribution and supplementation that are used to control brain Zn(2+)-levels in order to treat brain disorders are evaluated.

Zinc supplementation provides behavioral resiliency in a rat model of traumatic brain injury

Depression, anxiety, and impairments in learning and memory are all associated with traumatic brain injury (TBI). Because of the strong link between zinc deficiency, depression, and anxiety, in both humans and rodent models, we hypothesized that dietary zinc supplementation prior to injury could provide behavioral resiliency to lessen the severity of these outcomes after TBI. Rats were fed a marginal zinc deficient (5 ppm), zinc adequate (30 ppm), or zinc supplemented (180 ppm) diet for 4 weeks followed by a moderately-severe TBI using the well-established model of controlled cortical impact (CCI). Following CCI, rats displayed depression-like behaviors as measured by the 2-bottle saccharin preference test for anhedonia. Injury also resulted in evidence of stress and impairments in Morris water maze (MWM) performance compared to sham-injured controls. While moderate zinc deficiency did not worsen outcomes following TBI, rats that were fed the zinc supplemented diet for 4 weeks showed significantly attenuated increases in adrenal weight (p<0.05) as well as reduced depression-like behaviors (p<0.001). Supplementation prior to injury improved resilience such that there was not only significant improvements in cognitive behavior compared to injured rats fed an adequate diet (p<0.01), there were no significant differences between supplemented and sham-operated rats in MWM performance at any point in the 10-day trial. These data suggest a role for supplemental zinc in preventing cognitive and behavioral deficits associated with TBI.

Development of novel Zn2+ loaded nanoparticles designed for cell-type targeted drug release in CNS neurons: in vitro evidences

Intact synaptic function and plasticity are fundamental prerequisites to a healthy brain. Therefore, synaptic proteins are one of the major targets for drugs used as neuro-chemical therapeutics. Unfortunately, the majority of drugs is not able to cross the blood-brain barrier (BBB) and is therefore distributed within the CNS parenchyma. Here, we report the development of novel biodegradable Nanoparticles (NPs), made of poly-lactide-co-glycolide (PLGA) conjugated with glycopeptides that are able to cross the BBB and deliver for example Zn(2+) ions. We also provide a thorough characterization of loaded and unloaded NPs for their stability, cellular uptake, release properties, toxicity, and impact on cell trafficking. Our data reveal that these NPs are biocompatible, and can be used to elevate intracellular levels of Zn(2+). Importantly, by engineering the surface of NPs with antibodies against NCAM1 and CD44, we were able to selectively target neurons or glial cells, respectively. Our results indicate that these biodegradable NPs provide a potential new venue for the delivery Zn(2+) to the CNS and thus a means to explore the influence of altered zinc levels linked to neuropsychological disorders such as depression.

Zinc and neurogenesis: making new neurons from development to adulthood

Stem cell proliferation, neuronal differentiation, cell survival, and migration in the central nervous system are all important steps in the normal process of neurogenesis. These mechanisms are highly active during gestational and early neonatal brain development. Additionally, in select regions of the brain, stem cells give rise to new neurons throughout the human lifespan. Recent work has revealed key roles for the essential trace element zinc in the control of both developmental and adult neurogenesis. Given the prevalence of zinc deficiency, these findings have implications for brain development, cognition, and the regulation of mood.

Clinical implications of lipid peroxidation in acne vulgaris: old wine in new bottles

Acne vulgaris is a common dermatological disorder, one that is frequently associated with depression, anxiety and other psychological sequelae. In recent years there has been an increasing focus on the extent to which oxidative stress is involved in the pathophysiology of acne. Emerging studies have shown that patients with acne are under increased cutaneous and systemic oxidative stress. Indeed, there are indications that lipid peroxidation itself is a match that lights an inflammatory cascade in acne. The notion that lipid peroxidation is a 'starter gun' in acne is not a new one; here we review the nearly 50-year-old lipid peroxidation theory and provide a historical perspective to the contemporary investigations and clinical implications.

In addition, we present a novel hypothesis in which lipid peroxidation may be priming an increased susceptibility to co-morbid depression and anxiety in those with acne. The emerging research on the systemic burden of oxidative stress in acne sheds further light on the brain-skin axis. The recent findings also suggest potential avenues of approach for the treatment of acne via specific nutrients, dietary modifications, oral and topical interventions.