Zinc Deficiency and Depression

Zinc deficiency has multiple effects, including neurological and somatic symptoms. Zinc deficiency can lead to depression, increased anxiety, irritability, emotional instability, and induced deficits in social behavior. Clinical studies have shown that low levels of zinc intake contributes to the symptoms of depression and patients suffering from depression have a lower serum zinc level. Also the animal studies have shown an important role of dietary zinc deficiency in the induction of depressive‐like symptoms. Moreover, both preclinical and clinical studies have indicated the potential benefits of zinc supplementation as an adjunct to conventional antidepressant drugs or as a stand‐alone intervention. This chapter focuses on the role of the zinc deficiency in the pathogenesis of depression, changes in animal behavior induced by dietary zinc restriction, the role of zinc supplementation in the treatment of depression, and the possible mechanisms involved in these relationships. Both clinical and preclinical studies related to these findings will be discussed

Zinc transporters protein level in postmortem brain of depressed subjects and suicide victims

BACKGROUND: Major depressive disorder (MDD) is a serious psychiatric illness, associated with an increasing rate of suicide. The pathogenesis of depression may be associated with the disruption of zinc (Zn) homeostasis. In the brain, several proteins that regulate Zn homeostasis are present, including Zn transporters (ZnTs) which remove Zn from the cytosol. The present study was designed to investigate whether depression and suicide are associated with alterations in the expression of the ZnTs protein. METHODS: Protein levels of ZnT1, ZnT3, ZnT4, ZnT5 and ZnT6 were measured in postmortem brain tissue from two different cohorts. Cohort A contained 10 subjects diagnosed with MDD (7 were suicide victims) and 10 psychiatrically-normal control subjects and cohort B contained 11 non-diagnosed suicide victims and 8 sudden-death control subjects. Moreover, in cohort A we measured protein level of NMDA (GluN2A subunit), AMPA (GluA1 subunit) and 5-HT1A receptors and PSD-95. Proteins were measured in the prefrontal cortex (PFC) using Western blotting. In addition, Zn concentration was measured using a voltammetric method. RESULTS: There was a significant increase in protein levels of ZnT1, ZnT4, ZnT5 in the PFC in MDD, relative to control subjects, while ZnT3 protein level was decreased in MDD. There was no significant difference in the Zn concentration in the PFC between control and MDD subjects. Similarly, in the PFC of suicide victims (non-diagnosed), an increase in protein levels of ZnT1, ZnT4, ZnT5 and ZnT6 was observed. Conversely, protein levels of ZnT3 were decreased in both suicide victims and subjects with MDD, in comparison with control subjects. There was also a significant decrease in the protein level of GluA1, GluN2A, PSD-95 and 5-HT1A in MDD. CONCLUSIONS: Our studies suggest that alterations in Zn transport proteins are associated with the pathophysiology of MDD and suicide