The effects of oral zinc supplementation in the mouse

Zinc supplementation alters tissue distribution of arsenic in Mus musculus

Arsenic occurs naturally in the environment and humans can be exposed through food, drinking water and inhalation of air-borne particles. Arsenic exposure is associated with cardiovascular, pulmonary, renal, immunologic, and developmental toxicities as well as carcinogenesis. Arsenic displays dose-depen toxicities in target organs or tissues with elevated levels of arsenic. Zinc is an essential micronutrient with proposed protective benefits due to its antioxidant properties, integration into zinc-containing proteins and zinc-related immune signaling. In this study, we tested levels of arsenic and zinc in plasma, kidney, liver, and spleen as model tissues after chronic (42-day) treatment with either arsenite, zinc, or in combination. Arsenite exposure had minimal impact on tissue zinc levels with the exception of the kidney. Conversely, zinc supplementation of arsenite-exposed mice reduced the amount of arsenic detected in all tissues tested. Expression of transporters associated with zinc or arsenic influx and efflux were evaluated under each treatment condition. Significant effects of arsenite exposure on zinc transporter expression displayed tissue selectivity for liver and kidney, and was restricted to Zip10 and Zip14, respectively. Arsenite also interacted with zinc co-exposure for Zip10 expression in liver tissue. Pairwise comparisons show neither arsenite nor zinc supplementation alone significantly altered expression of transporters utilized by arsenic. However, significant interactions between arsenite and zinc were evident for Aqp7 and Mrp1 in a tissue selective manner. These findings illustrate interactions between arsenite and zinc leading to changes in tissue metal level and suggest a potential mechanism by which zinc may offer protection from arsenic toxicities.

Enterocyte-specific deletion of metal transporter Zip14 (Slc39a14) alters intestinal homeostasis through epigenetic mechanisms

Zinc has anti-inflammatory properties using mechanisms that are unclear. Zip14 (Slc39a14) is a zinc transporter induced by proinflammatory stimuli and is highly expressed at the basolateral membrane of intestinal epithelial cells (IECs). Enterocyte-specific Zip14 ablation (Zip14ΔIEC) in mice was developed to study the functions of this transporter in enterocytes. This gene deletion led to increased intestinal permeability, increased IL-6 and IFNγ expression, mild endotoxemia, and intestinal dysbiosis. RNA sequencing was used for transcriptome profiling. These analyses revealed differential expression of specific intestinal proinflammatory and tight junction (TJ) genes. Binding of transcription factors, including NF-κβ, STAT3, and CDX2, to appropriate promoter sites of these genes supports the differential expression shown with chromatin immunoprecipitation assays. Total histone deacetylase (HDAC), and specifically HDAC3, activities were markedly reduced with Zip14 ablation. Intestinal organoids derived from ΔIEC mice display TJ and cytokine gene dysregulation compared with control mice. Differential expression of specific genes was reversed with zinc supplementation of the organoids. We conclude that zinc-dependent HDAC enzymes acquire zinc ions via Zip14-mediated transport and that intestinal integrity is controlled in part through epigenetic modifications.NEW & NOTEWORTHY We show that enterocyte-specific ablation of zinc transporter Zip14 (Slc39a14) results in selective dysbiosis and differential expression of tight junction proteins, claudin 1 and 2, and specific cytokines associated with intestinal inflammation. HDAC activity and zinc uptake are reduced with Zip14 ablation. Using intestinal organoids, the expression defects of claudin 1 and 2 are resolved through zinc supplementation. These novel results suggest that zinc, an essential micronutrient, influences gene expression through epigenetic mechanisms.

Physiological and histological effects of (zinc and iron) oxide nanoparticles on some fertility parameters in female mice

Nowadays nanoparticles have widespread application in various industriesbecause of their special and unique features, there are many studies in sideeffects of nanomaterial. This study done by 40 white female mice withevery other day intraperitoneally injection of low and high doses of both ofZnO kg of body weight) and FeOnanoparticles (5 and 40 mg/kg). After a 15 days period, the mice weresacrificed and blood samples were collected for hormone analysis, andtissue samples for morphometric studies.Statistical Analysis shows significant differences in LH, Estrogen,Progesterone hormone levels between groups, while there are insignificantdifferences in Follicle stimulating hormone (FSH) level between thegroups compared with its level in the control group.The results also show that the highest level of LH reach 7.2 mIU/ml in thegroups treated with low dose of zinc oxide, the highest level of FSH reach4.58 mIU/ml in the groups treated with low dose of zinc oxide, the highestlevel of Estrogen hormone reach 69.5 ng/ml in the groups treated with lowof dose zinc oxide and the highest level of Progesterone reach 1.9 ng/ml inthe groups treated with high dose iron oxide. We conclude from the resultsthat the low doses of ZnO has benefits in increasing fertility through highlevel of reproductive hormones, while the high levels of nanoparticlesreduce fertility and there is a relation between FeO nanoparticles andprogesterone levels which may need more future studies.Morphometric study of the ovary show increase in Follicular stagesnumber range in the group treated with Low dose ZnO in compare with itsrange in the control groups. The lower range was belong to the grouptreated with the high dose of FeO. No significant differences has beenfound in the diameter mean of the different follicular phases between thegroup treated with low dose of ZnO NPs in compared with the controlgroup. High dose of ZnO NPs cause significant increase in the diametermean of Primordial follicles in compared with the control group. Low andhigh dose FeO NPs treated groups show significant reduction in thediameter mean of the different follicular phases in compared with thecontrol group.

Content of bioelements in the lungs and liver in rats with alimentary obesity

The synchrotron radiation X-ray fluorescence technique (SRXRF) was applied to the determination of K, Ca, Mn, Fe, Cu, Zn, Se, Br, Rb, and Sr concentrations in the liver and lungs in Wistar rats. The animals in the experiment included (1) healthy rats, (2) rats with alimentary obesity (AO), and (3) rats with alimentary obesity that were being given zinc sulphate with water for a long time (АО+Zn). Each group was divided into two subgroups. The experiment with the first subgroup was terminated with the animals in the state of physiological hunger and subsequent retrieval of liver and lung tissue, while the animals of the second subgroup were sacrificed two hours after ingestion of lard. The rats in physiological hunger manifested intergroup differences in the content of the bioelements (BEs) neither in the liver nor in the lungs. The rats with AO, as compared with the healthy animals, demonstrated in physiological hunger redistribution of inter-element correlations (IECs), which is an indirect reflection of sustained metabolic disorder. Additional zinc in the rats' ration did not affect their body weight and the concentration of the BEs (including zinc) in the liver and the lungs. However, the IECs in the tissues of these animals in physiological hunger also changed. This redistribution differed from that in the rats with AO. The IECs soon after ingestion of lard also changed, which also reflects sustained changes in the metabolism in the animals.

Induction of regulatory T cells in Th1-/Th17-driven experimental autoimmune encephalomyelitis by zinc administration

The essential trace element zinc is indispensable for proper immune function as zinc deficiency accompanies immune defects and dysregulations like allergies, autoimmunity and an increased presence of transplant rejection. This point to the importance of the physiological and dietary control of zinc levels for a functioning immune system. This study investigates the capacity of zinc to induce immune tolerance. The beneficial impact of physiological zinc supplementation of 6 μg/day (0.3mg/kg body weight) or 30 μg/day (1.5mg/kg body weight) on murine experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis with a Th1/Th17 (Th, T helper) cell-dominated immunopathogenesis, was analyzed. Zinc administration diminished EAE scores in C57BL/6 mice in vivo (P<.05), reduced Th17 RORγT(+) cells (P<.05) and significantly increased inducible iTreg cells (P<.05). While Th17 cells decreased systemically, iTreg cells accumulated in the central nervous system. Cumulatively, zinc supplementation seems to be capable to induce tolerance in unwanted immune reactions by increasing iTreg cells. This makes zinc a promising future tool for treating autoimmune diseases without suppressing the immune system.

Survival study of metallothionein-1 transgenic mice and respective controls (C57BL/6J): influence of a zinc-enriched environment

The role of metallothioneins (MTs) in aging is not completely understood. Several studies have shown evidence that these proteins could represent a defense system against oxidative damage, but survival studies on mice overexpressing MTs are poor. Here we describe a survival study performed on old MT-1-overexpressing mice (MT-TG) and their respective controls (C57BL/6J) fed a standard or zinc (Zn)-supplemented diet. MT-TG mice had significantly increased survival compared with control. Zn supplementation affects the survival curves of MT-TG and C57BL/6J mice differently. This study poses the basis for intervention based on gene therapy with MTs to enhance the health span of laboratory mice.

Modulation of Zn-induced hyperinsulinemia/insulin resistance in Wistar rat fed modified poultry egg(psi)

Excessive bioavailability of Zn causes Cu and Mg deficiencies resulting in hyperglycemia and hyperinsulinemia/insulin resistance. These defects may ameliorate if the ionic imbalance in them is corrected. In view of this, three groups of rats were included in this study. Initially, they were fed on semi-synthetic equicalories basal diet containing 20 mg Zn (control, group-I), on 40 mg Zn (group-II) and 80 mg Zn/kg diet (group-III) respectively for 3 months. Thereafter, half of the rats in group-II and III were shifted on Cu and Mg enriched modified poultry egg (ME(Psi)) mixed diets (groups-IIME and IIIME) while the remaining were continued to feed on their respective diets for another 3 months completing a total of 6 months. Hyperglycemia, hyperinsulinemia, hypercortisolemia, hyperzincemia, hypercupremia and hypermagnesaemia with corresponding increase of lipid droplets in the zona fasciculate of adrenal cortex and reduction in liver glycogen content in rats of groups-II and III were recorded. These changes were linked with a rise in Zn and fall in Cu and Mg in their liver. The addition of ME(Psi) in their diets led to fall of Zn and rise in liver Cu and Mg, and fall in serum Zn, Cu and Mg resulting in the improvement of glucose disposal, increase in insulin sensitivity, reduction in lipid droplets in zona fasciculate and increase in glycogen content in the liver approaching closer to the control group-I. The data suggest that these ME(Psi) can serve as non-pharmacological dietary supplement to prevent insulin resistance/hyperinsulinemia in populations who are at higher risk of diabetes mellitus either due to their genetic predisposition of excessive absorption and retention of Zn or due to higher Zn content in the food chain.

Zinc effects on nickel dermatitis in the guinea pig

Prevention of NiSO4 induced allergic contact dermatitis (ACD) using ZnSO4 in drinking water was studied in a guinea pig model. Without ZnSO4 interventions, nickel (Ni)-exposure resulted in significantly higher (p less than 0.05) stimulation indices (SIs) as compared to non-exposed controls, using NiSO4 as an allergen in the lymphocyte transformation test (LTT). Oral intake of ZnSO4 at both 250 micrograms/ml double-distilled deionized water (DDD) and 500 micrograms/ml DDD resulted in lower SIs than those of control guinea pigs drinking only DDD; the 250 micrograms/ml group had significantly lower SIs (p = 0.025) than controls. There was no significant correlation between intradermal test responses and the SI values of individual guinea pigs exposed to NiSO4. Mean zinc (Zn) concentrations in skin and in whole blood were not statistically different between the NiSO4 exposed control and Zn supplemented groups, nor between Ni-sensitive and non-sensitive animals within groups. The rôle of Zn homeostasis, rôle of the Langerhans cell, effect of Zn supplementation on Ni ACD in other species, and possible blocking effects of other metals should be investigated in future studies.

Zinc toxicity in ruminants

Four natural occurrences of zinc toxicity in sheep and one in calves were studied. To assist in the confirmation of a diagnosis of zinc toxicity, 2 experiments were conducted in which sheep were given toxic amounts of zinc. The clinical findings, clinical pathology, and gross and microscopic pathology are given. Clinical manifestations included inappetance, loss of condition, diarrhoea with dehydration or subcutaneous oedema, profound weakness and jaundice. Significant rises in the concentration of zinc were usually found in the liver, kidney and pancreas, but occasionally in only 1 or 2 of these organs. Many affected sheep were anaemic. Pathological changes were found in the pancreas, kidney, liver, rumen, abomasum, small intestine and adrenal gland. Lesions in the kidney and abomasum apparently made the most significant contribution to the deterioration in health of affected animals, but the pancreas was the only organ consistently affected. The degenerative changes in the pancreas were mainly restricted to the exocrine portion of the organ, and regeneration of the damaged tissue was observed although exposure to toxic amounts of zinc continued. Attention is drawn to the importance of the pancreas in the diagnosis of zinc toxicity and in estimating the period of exposure.