Zinc as a potential coadjuvant in therapy for type 2 diabetes

A New Concept in Antidiabetic Therapeutics: A Concerted Removal of Labile Iron and Intracellular Deposition of Zinc

BACKGRUOUND

The inflammatory process is known to be an integral part of the pathophysiology of type 2 diabetes mellitus (T2DM). The "labile," redox-active iron, serving as a catalyst in Fenton reaction, producing the deleterious reactive oxygen species, triggering and maintaining inflammation, is hypothesized to play a causative role in this process. Concenter Biopharma continued the development of a new platform of iron chelators (Zygosids), first initiated at the Hebrew University of Jerusalem, Israel (HUJI), acting via the novel mechanism, based on a sequestration of the labile redox-active iron and its substitution by zinc or gallium. The mode of action of Zygosids is based on the higher affinity of the metal-binding moiety of the complex to Fe3+ in comparison to already bound ion, leading to rapid release of the ion of another metal and chelation of Fe3+. Concomitantly, zinc ion, released by the complex, is known for its antidiabetic and anti-inflammatory role.

METHODS

The therapeutic effect of zinc-desferrioxamine (Zygosid-50) and gallium-desferrioxamine, was tested on fat sand rat (Psammomys obesus) model of diet-induced T2DM and on Leprdb transgenic diabetic mice.

RESULTS

Zygosids demonstrated an ability to noticeably reduce blood glucose and insulin levels and improve the lipid profile. Moreover, an ability to mitigate insulin resistance by >90% was shown on the sand rat model. In addition, a potent anti-inflammatory effect, expressed as a diminishment of the proinflammatory cytokines in tissue levels, was demonstrated.

CONCLUSION

Zygosids demonstrated robust therapeutic efficacy in treatment of T2DM. Importantly, no adverse effects were detected, in all the experiments, indicating high safety profile.

Zinc Oxide Nanoparticles and Vitamin C Ameliorate Atrazine-Induced Hepatic Apoptosis in Rat via CYP450s/ROS Pathway and Immunomodulation

Atrazine, as an herbicide, is used widely worldwide. Because of its prolonged persistence in the environment and accumulation in the body, atrazine exposure is a potential threat to human health. The present study evaluated the possible protective effects of zinc oxide nanoparticles and vitamin C against atrazine-induced hepatotoxicity in rats. Atrazine administered to rats orally at a dose of 300 mg/kg for 21 days caused liver oxidative stress as it increased malondialdehyde (MDA) formation and decreased reduced glutathione (GSH) contents. Atrazine induced inflammation accompanied by apoptosis via upregulation of hepatic gene expression levels of NF-κB, TNF-α, BAX, and caspase-3 and downregulation of Bcl-2 gene expression levels. Additionally, it disturbed the metabolic activities of cytochrome P450 as it downregulated hepatic gene expression levels of CYP1A1, CYP1B1, CYP2E1. The liver function biomarkers were greatly affected upon atrazine administration, and the serum levels of AST and ALT were significantly increased, while BWG%, albumin, globulins, and total proteins levels were markedly decreased. As a result of the above-mentioned influences of atrazine, histopathological changes in liver tissue were recorded in our findings. The administration of zinc oxide nanoparticles or vitamin C orally at a dose of 10 mg/kg and 200 mg/kg, respectively, for 30 days prior and along with atrazine, could significantly ameliorate the oxidative stress, inflammation, and apoptosis induced by atrazine and regulated the hepatic cytochrome P450 activities. Furthermore, they improved liver function biomarkers and histopathology. In conclusion, our results revealed that zinc oxide nanoparticles and vitamin C supplementations could effectively protect against atrazine-induced hepatotoxicity.

Comparison of the Potential Relative Bioaccessibility of Zinc Supplements-In Vitro Studies

The aim of this study was to determine the potential relative bioaccessibility of zinc (Zn) from selected dietary supplements during in vitro digestion. The bioaccessibility of Zn was evaluated in dietary supplements differing in the pharmaceutical form, content, dose, and chemical form of the element. The content of Zn was determined by flame atomic absorption spectrometry. The applied method was validated, and results were characterised by good linearity (R² = 0.998), recovery (109%), and accuracy (0.02%). As a result of the tests conducted, it was found that the bioaccessibility of Zn from dietary supplements varied and ranged from 1.1% to 9.4%. The highest bioaccessibility was found for zinc diglycinate and the lowest for zinc sulphate. In 9 out of 10 tested dietary supplements, the determined Zn content was higher than the one declared by the producer (up to 161%). The estimated tolerable upper intake level (UL) was exceeded by five of the analysed dietary supplements (123-146%). The analysed dietary supplements were assessed in terms of compliance with the information contained on the product packaging, based on current Polish and European legal regulations. The qualitative assessment was performed according to the United States Pharmacopoeia (USP) guidelines.

Nano‑zinc enhances gene regulation of non‑specific immunity and antioxidative status to mitigate multiple stresses in fish

The toxicity of ammonia surged with arsenic pollution and high temperature (34 °C). As climate change enhances the pollution in water bodies, however, the aquatic animals are drastically affected and extinct from nature. The present investigation aims to mitigate arsenic and ammonia toxicity and high-temperature stress (As + NH₃ + T) using zinc nanoparticles (Zn-NPs) in Pangasianodon hypophthalmus. Zn-NPs were synthesized using fisheries waste to developing Zn-NPs diets. The four isonitrogenous and isocaloric diets were formulated and prepared. The diets containing Zn-NPs at 0 (control), 2, 4 and 6 mg kg^-1 diets were included. Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-s-transferase (GST) were noticeably improved using Zn-NPs diets in fish reared under with or without stressors. Interestingly, lipid peroxidation was significantly reduced, whereas vitamin C and acetylcholine esterase were enhanced with supplementation of Zn-NPs diets. Immune-related attributes such as total protein, globulin, albumin, myeloperoxidase (MPO), A:G ratio, and NBT were also improved with Zn-NPs at 4 mg kg^-1 diet. The immune-related genes such as immunoglobulin (Ig), tumor necrosis factor (TNFα), and interleukin (IL1b) were strengthening in the fish using Zn-NPs diets. Indeed, the gene regulations of growth hormone (GH), growth hormone regulator (GHR1), myostatin (MYST) and somatostatin (SMT) were significantly improved with Zn-NPs diets. Blood glucose, cortisol and HSP 70 gene expressions were significantly upregulated by stressors, whereas the dietary Zn-NPs downregulated the gene expression. Blood profiling (RBC, WBC and Hb) was reduced considerably with stressors (As + NH₃ + T), whereas Zn-NPs enhanced the RBC, WBC, and Hb count in fish reread in control or stress conditions. DNA damage-inducible protein gene and DNA damage were significantly reduced using Zn-NPs at 4 mg kg^-1 diet. Moreover, the Zn-NPs also enhanced the arsenic detoxification in different fish tissues. The present investigation revealed that Zn-NPs diets mitigate ammonia and arsenic toxicity, and high-temperature stress in P. hypophthalmus.

Antioxidant, Anti-inflammatory, and Immunomodulatory Roles of Nonvitamin Antioxidants in Anti-SARS-CoV-2 Therapy

Viral pathologies encompass activation of pro-oxidative pathways and inflammatory burst. Alleviating overproduction of reactive oxygen species and cytokine storm in COVID-19 is essential to counteract the immunogenic damage in endothelium and alveolar membranes. Antioxidants alleviate oxidative stress, cytokine storm, hyperinflammation, and diminish the risk of organ failure. Direct antiviral roles imply: impact on viral spike protein, interference with the ACE2 receptor, inhibition of dipeptidyl peptidase 4, transmembrane protease serine 2 or furin, and impact on of helicase, papain-like protease, 3-chyomotrypsin like protease, and RNA-dependent RNA polymerase. Prooxidative environment favors conformational changes in the receptor binding domain, promoting the affinity of the spike protein for the host receptor. Viral pathologies imply a vicious cycle, oxidative stress promoting inflammatory responses, and vice versa. The same was noticed with respect to the relationship antioxidant impairment-viral replication. Timing, dosage, pro-oxidative activities, mutual influences, and interference with other antioxidants should be carefully regarded. Deficiency is linked to illness severity.

Modulation of Zinc Transporter Expressions by Additional Zinc in C2C12 Cells Cultured in a High Glucose Environment and in the Presence of Insulin or Interleukin-6

Zn status has been related to various chronic diseases presenting oxidative stress and inflammation, such as type 2 diabetes. Zn supplementation has been suggested to be a potential coadjuvant in the management of this condition. Zn transporters constitute a key component in the maintenance of Zn homeostasis. Our aim was to evaluate the modulatory effect of additional Zn (10 or 100 µM; as a ZnSO₄*7H₂0) on the mRNA relative expression of selected Zn transporters (ZnT1, ZnT5, ZnT7, ZIP6, ZIP7, ZIP10, ZIP14), in myoblast (C2C12) cells cultured in normal (10 mM) and high glucose (30 mM), and in the absence or presence of insulin (1 nM), and interleukin-6 (IL-6; 5 nM) for 24 h. The main findings of our study were that in high glucose conditions in absence of insulin or IL-6, additional Zn increased ZnT1 and ZIP6, and decreased ZnT5 and ZIP7 expressions. However, this situation is modified by insulin, where incremental Zn induced increased expressions of ZnT1, ZnT5, and all the ZIP transporters studied. In high glucose conditions and in the presence of IL-6, additional Zn caused increased expressions of ZnT7, ZIP7, and ZIP14, compared with results in the absence of IL-6. This study provides preliminary evidence for the differential expression of selected Zn transporters in C2C12 cells subjected to high glucose and incremental Zn, suggesting that important changes in intracellular Zn distribution take place in response to inflammatory and high-insulin environments. Further study is necessary to understand the implications of these findings.

Antioxidant Effect of Coenzyme Q10 in the Prevention of Oxidative Stress in Arsenic-Treated CHO-K1 Cells and Possible Participation of Zinc as a Pro-Oxidant Agent

Oxidative stress is an imbalance between levels of reactive oxygen species (ROS) and antioxidant enzymes. Compounds with antioxidant properties, such as coenzyme Q10 (CoQ10), can reduce cellular imbalance caused by an increase in ROS. CoQ10 participates in modulating redox homeostasis due to its antioxidant activity and its preserving mitochondrial functions. Thus, the present study demonstrated the protective effects of CoQ10 against oxidative stress and cytotoxicity induced by arsenic (As). Antioxidant capacity, formation of hydroperoxides, generation of ROS, and the effect on cellular viability of CoQ10, were investigated to determine the protective effect of CoQ10 against As and pro-oxidant compounds, such as zinc. Cell viability assays showed that CoQ10 is cytoprotective under cellular stress conditions, with potent antioxidant activity, regardless of the concentration tested. Zn, when used at higher concentrations, can increase ROS and show a pro-oxidant effect causing cell damage. The cytotoxic effect observed for As, Zn, or the combination of both could be prevented by CoQ10, without any decrease in its activity at cellular levels when combined with Zn.

Clinical efficacy of zinc supplementation in improving antioxidant defense system: A comprehensive systematic review and time-response meta-analysis of controlled clinical trials

Oxidative stress is a contributing factor to many chronic diseases. It has been investigated that zinc (Zn) may enhance the antioxidant defense. The current dose-response and time-response meta-analysis aims to determine the efficacy of Zn supplementation in improving antioxidant defense. Scopus, PubMed/Medline, Web of Science, and Embase databases were searched systematically up to December 30, 2020. Meta-analysis was performed on human controlled clinical trials using random effects method. To find any source of heterogeneity, subgroup analysis and meta-regression were performed. Trim and fill analysis was used for adjusting the publication bias. To find any non-linear relationship between variables and effect size, dose-response and time-response analyses were performed. Cochrane Collaboration's tool was used for evaluating the quality assessment. A total of 23 controlled clinical trials were analyzed. The range of Zn supplementation duration in various studies was within 4-24 weeks. Zn supplementation did not have beneficial effects on glutathione peroxidase (GPx) activity (SMD = -0.34 U/g; 95% CI: -0.93, 0.25; P = 0.258). There were significant increasing effects of Zn supplementation on glutathione (GSH) (SMD = 1.28 μmol/l; 95% CI: 0.42, 2.14; P = 0.003) and total antioxidant capacity (TAC) levels (SMD = 1.39 mmol/l; 95% CI: 0.44, 2.35; P = 0.004). Zn had ameliorative effects on superoxide dismutase (SOD) activity after elimination of publication bias (SMD: 0.84 U/g; 95% CI: 0.12, 1.56, P < 0.05). Zn could also elevate GSH and TAC levels, plus SOD activity after modifying the publication bias. Finally, Zn had no significant effect on GPx activity.

Zinc and Selenium in Inflammatory Bowel Disease: Trace Elements with Key Roles?

Inflammatory bowel disease (IBD) is a chronic inflammatory condition that may emerge at a young age and often lasts for life. It often goes through phases of recurrence and remission and has a devastating effect on quality of life. The exact etiology of the disease is still unclear, but it appears that an inappropriate immune response to intestinal flora bacteria in people with a genetic predisposition may cause the disease. Managing inflammatory bowel disease is still a serious challenge. Oxidative stress and free radicals appear to be involved in the pathogenesis of this disease, and a number of studies have suggested the use of antioxidants as a therapeutic approach. The antioxidant and anti-inflammatory properties of some trace elements have led some of the research to focus on studying these trace elements in inflammatory bowel disease. Zinc and selenium are among the most important trace elements that have significant anti-inflammatory and antioxidant properties. Some studies have shown the importance of these trace elements in inflammatory bowel disease. In this review, we have attempted to provide a comprehensive overview of the findings of these studies and to gather current knowledge about the association of these trace elements with the inflammatory process and inflammatory bowel disease.

Relationship Between Zinc Status and DNA Oxidative Damage in Patients with Type 2 Diabetes Mellitus

Although zinc deficiency increases the risk of oxidative DNA damage, data regarding the association between zinc and oxidative DNA damage in diabetes are controversial. In this article, we focus on serum zinc levels and its relation to an established biomarker of oxidative DNA damage (8-hydroxy-2-deoxyguanosine) in patients with type 2 diabetes, and to ascertain the beneficial effects of zinc supplementation on the level of oxidative DNA damage. The study consisted of 2 interrelated parts: The first part was a cross-sectional study conducted on patients with type 2 diabetes (n = 297) and healthy individuals (n = 188). The second part was an interventional study that enrolled 38 diabetic patients with low zinc status and high DNA damage. The demographic parameters including age, gender, and body mass index were recorded, and DNA damage marker through 8-hydroxy-2-deoxyguanosine levels, and zinc status of serum zinc, was measured. Significantly higher 8-hydroxy-2-deoxyguanosine levels (P < 0.00) together with lower zinc levels (P < 0.001) were found in the diabetics compared to healthy controls. Patients with low zinc status had higher levels of 8-hydroxy-2-deoxyguanosine compared to patients with normal zinc status. In diabetic patients, a negative correlation of 8-hydroxy-2-deoxyguanosine was observed with zinc (P = 0.070). Zinc supplementation showed a significant decrease in 8-hydroxy-2-deoxyguanosine by (26.0%) and increased in serum zinc by (42.0%). Elevated 8-hydroxy-2-deoxyguanosine levels in conjunction with low zinc status may indicate a high degree of oxidative DNA damage in diabetic patients. The results confirm that zinc supplementation in this group may help correct abnormal levels of 8-hydroxy-2-deoxyguanosine.

The role of labile Zn2+ and Zn2+-transporters in the pathophysiology of mitochondria dysfunction in cardiomyocytes

An important energy supplier of cardiomyocytes is mitochondria, similar to other mammalian cells. Studies have demonstrated that any defect in the normal processes controlled by mitochondria can lead to abnormal ROS production, thereby high oxidative stress as well as lack of ATP. Taken into consideration, the relationship between mitochondrial dysfunction and overproduction of ROS as well as the relation between increased ROS and high-level release of intracellular labile Zn²⁺, those bring into consideration the importance of the events related with those stimuli in cardiomyocytes responsible from cellular Zn²⁺-homeostasis and responsible Zn²⁺-transporters associated with the Zn²⁺-homeostasis and Zn²⁺-signaling. Zn²⁺-signaling, controlled by cellular Zn²⁺-homeostatic mechanisms, is regulated with intracellular labile Zn²⁺ levels, which are controlled, especially, with the two Zn²⁺-transporter families; ZIPs and ZnTs. Our experimental studies in mammalian cardiomyocytes and human heart tissue showed that Zn²⁺-transporters localizes to mitochondria besides sarco(endo)plasmic reticulum and Golgi under physiological condition. The protein levels as well as functions of those transporters can re-distribute under pathological conditions, therefore, they can interplay among organelles in cardiomyocytes to adjust a proper intracellular labile Zn²⁺ level. In the present review, we aimed to summarize the already known Zn²⁺-transporters localize to mitochondria and function to stabilize not only the cellular Zn²⁺ level but also cellular oxidative stress status. In conclusion, one can propose that a detailed understanding of cellular Zn²⁺-homeostasis and Zn²⁺-signaling through mitochondria may emphasize the importance of new mitochondria-targeting agents for prevention and/or therapy of cardiovascular dysfunction in humans.

Vitamin D3 as adjuvant in the treatment of type 2 diabetes mellitus: modulation of genomic and biochemical instability

Type 2 diabetes mellitus has undergone a worldwide growth in incidence in the world and has now acquired epidemic status. There is a strong link between type 2 diabetes and vitamin D deficiency. Because vitamin D has beneficial effects on glucose homeostasis, the aim of this study was to evaluate the influence of vitamin D3 supplementation on the modulation of glycaemic control and other metabolic effects, as well as modulation of genomic instability in patients with type 2 diabetes. We evaluated 75 patients with type 2 diabetes, registered in the Integrated Clinics of the University of Southern Santa Catarina. Participants received 4000 IU of vitamin D3 (25(OH)D) supplementation daily for 8 weeks. Blood samples were collected at the beginning and at the end of the supplementation, and 4 weeks after the end of supplementation. The glycidic and lipid profiles [total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein and triglycerides], oxidative stress, DNA damage and 25(OH)D levels were evaluated. Vitamin D3 supplementation for 8 weeks showed enough to significantly increase blood levels of 25(OH)D. A significant difference in lipid profile was observed only in non-HDL cholesterol. Significant changes were observed in glucose homeostasis (fasting glucose and serum insulin) and, in addition, a reduction in the parameters of oxidative stress and DNA damage. There was a significant reduction in the values of 25(OH)D 4 weeks after the end of the supplementation, but levels still remained above baseline. Use of vitamin D supplementation can be an ally in the health modulation of patients with type 2 diabetes mellitus.

Association between zinc nutritional status and glycemic control in individuals with well-controlled type-2 diabetes

BACKGROUND/OBJECTIVE

Interest in healthy properties of food and nutrients as co-adjuvant in type-2 diabetes therapy has increased in recent years. Zinc supplementation trials have shown improvements in glycemic control in these patients, although it seems dependent on zinc status of the individuals. The objective of this study was to evaluate the relationship between zinc nutritional status and glucose homeostasis in patients with type-2 diabetes.

SUBJECTS/METHODS

Eighty patients with well controlled type-2 diabetes were recruited and clinical, anthropometric and dietary evaluations were performed. One week after, insulin sensitivity and beta cell function were assessed by a modified Frequently Sampled Intravenous Glucose Tolerance Test. Zinc status was assessed by plasma zinc and the size of rapidly Exchangeable Zinc Pool (EZP); zinc intake was also determined. Glucagon concentration was evaluated in a subsample of 36 patients.

RESULTS

Patients presented a normal zinc status although zinc intake was lower than recommended. Overall, no associations were observed between zinc status and glycemic control markers. Nevertheless, positive correlations were observed between EZP and fasting insulin concentration (ρ = 0.393, p = 0.021) and HOMA-IR (ρ = 0.386, p = 0.024) in women, and between plasma zinc concentration and HbA1c (ρ = 0.342, p = 0.020) in men.

CONCLUSIONS

No significant associations were found between zinc status and glycemic control parameters in patients with well-controlled type 2 diabetes and normal zinc status, although low-degree gender-dependent associations were observed. Further research is required to assess the role of zinc status in zinc deficient patients.

Zinc and Oxidative Stress: Current Mechanisms

Oxidative stress is a metabolic dysfunction that favors the oxidation of biomolecules, contributing to the oxidative damage of cells and tissues. This consequently contributes to the development of several chronic diseases. In particular, zinc is one of the most relevant minerals to human health, because of its antioxidant properties. This review aims to provide updated information about the mechanisms involved in the protective role of zinc against oxidative stress. Zinc acts as a co-factor for important enzymes involved in the proper functioning of the antioxidant defense system. In addition, zinc protects cells against oxidative damage, acts in the stabilization of membranes and inhibits the enzyme nicotinamide adenine dinucleotide phosphate oxidase (NADPH-Oxidase). Zinc also induces the synthesis of metallothioneins, which are proteins effective in reducing hydroxyl radicals and sequestering reactive oxygen species (ROS) produced in stressful situations, such as in type 2 diabetes, obesity and cancer. Literature provides strong evidence for the role of zinc in the protection against oxidative stress in several diseases.

Zinc Status and Risk of Cardiovascular Diseases and Type 2 Diabetes Mellitus-A Systematic Review of Prospective Cohort Studies

Zinc is an essential trace element with proposed therapeutic effects in Type 2 diabetes mellitus (DM), however, the associations between zinc status and the prospective risks of cardiovascular diseases (CVD) and Type 2 DM have not been evaluated. The current systematic review aims to determine the relationships between zinc intake or plasma/serum zinc levels and prospective incidence of CVD and Type 2 DM. Fourteen papers describing prospective cohort studies were included, reporting either CVD (n = 91,708) and/or Type 2 DM (n = 334,387) outcomes. Primary analyses from four out of five studies reported no association between zinc intake and CVD events, when adjusted for multiple variables. Higher serum zinc level was associated with lower risk of CVD in three out of five studies; pronounced effects were observed in vulnerable populations, specifically those with Type 2 DM and patients referred to coronary angiography. The limited evidence available suggests no association between zinc status and Type 2 DM risk. Further investigations into the mechanisms of zinc's action on the pathogenesis of chronic diseases and additional evidence from observational studies are required to establish a recommendation for dietary zinc in relation to the prevention of CVD and Type 2 DM.

Does Zinc Really "Metal" with Diabetes? The Epidemiologic Evidence

Zinc (Zn) is important in a number of processes related to insulin secretion and insulin activity in peripheral tissues, making this element an interesting potential co-adjuvant in the treatment of patients with type 2 diabetes (T2D). This issue has been matter of interest in recent years. The available evidence is analyzed in this review. Information from epidemiologic studies evaluating the relationship between Zn and T2D is inconsistent. Furthermore, few studies examined the association between Zn status and insulin action and/or glucose homeostasis. In terms of usefulness of Zn as a preventive agent for T2D development, information is insufficient to reach firm conclusions. Results from Zn supplementation trials found some positive effects only in those with initial sub normal Zn status in a significant proportion of individuals. In conclusion, the effect of Zn on patients with type 2 diabetes is still an open question, and better study designs are needed to clarify the real impact and characteristics of the Zn-diabetes interaction.

ZnCl2 sustains the adriamycin-induced cell death inhibited by high glucose

Hyperglycemia, the condition of high blood glucose, is typical of diabetes and obesity and represents a significant clinical problem. The relationship between hyperglycemia and cancer risk has been established by several studies. Moreover, hyperglycemia has been shown to reduce cancer cell response to therapies, conferring resistance to drug-induced cell death. Therefore, counteracting the negative effects of hyperglycemia may positively improve the cancer cell death induced by chemotherapies. Recent studies showed that zinc supplementation may have beneficial effects on glycemic control. Here we aimed at evaluating whether ZnCl2 could counteract the high-glucose (HG) effects and consequently restore the drug-induced cancer cell death. At the molecular level we found that the HG-induced expression of genes known to be involved in chemoresistance (such as HIF-1α, GLUT1, and HK2 glycolytic genes, as well as NF-κB activity) was reduced by ZnCl2 treatment. In agreement, the adryamicin (ADR)-induced apoptotic cancer cell death was significantly impaired by HG and efficiently re-established by ZnCl2 cotreatment. Mechanistically, the ADR-induced c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) phosphorylation, inhibited by HG, was efficiently restored by ZnCl2. The JNK involvement in apoptotic cell death was assessed by the use of JNK dominant-negative expression vector that indeed impaired the ZnCl2 ability to restore drug-induced cell death in HG condition. Altogether, these findings indicate that ZnCl2 supplementation efficiently restored the drug-induced cancer cell death, inhibited by HG, by both sustaining JNK activation and counteracting the glycolytic pathway.

Inhibitory effect of zinc on the advanced glycation end product-induced apoptosis of mouse osteoblastic cells

Osteoporosis and diabetes have become serious health problems worldwide. Previous studies have suggested that diabetes is associated with osteoporosis and increased fracture risk. However, the mechanism underlying diabetes‑induced osteoporosis remains to be elucidated. Therefore, the present study aimed to examine the mechanism underlying diabetes‑induced osteoporosis, and determine the protective effects of zinc, which is known to be closely associated with osteoporosis and diabetes. The results of the present study demonstrated that zinc inhibited advanced glycation end product (AGE)‑induced MC3T3‑E1 cell apoptosis by attenuating the production of reactive oxygen species, inhibiting caspase‑3 and caspase‑9 activation, and inhibiting the release of cytochrome c from between the mitochondria and the cytosol. Furthermore, zinc was found to protect cells against AGE‑induced apoptosis via the mitogen‑activated protein kinase/extracellular signal‑regulated kinase and phosphoinositide 3‑kinase/AKT signaling pathways. In conclusion, these findings enable a better understanding of the mechanism underlying diabetes‑induced osteoporosis, and may indicate a novel target for its prevention and treatment.

Modulation of (14) C-labeled glucose metabolism by zinc during aluminium induced neurodegeneration

Aluminium (Al) is one of the most prominent metals in the environment and is responsible for causing several neurological disorders, including Alzheimer's disease. On the other hand, zinc (Zn) is an essential micronutrient that is involved in regulating brain development and function. The present study investigates the protective potential of Zn in the uptake of (14) C-labeled amino acids and glucose and their turnover in rat brain slices during Al intoxication. Male Sprague Dawley rats (140-160 g) were divided into four different groups: normal control, Al treated (100 mg/kg body weight/day via oral gavage), Zn treated (227 mg/liter in drinking water), and Al + Zn treated. Radiorespirometric assay revealed an increase in glucose turnover after Al exposure that was attenuated after Zn treatment. Furthermore, the uptake of (14) C-labeled glucose was increased after Al treatment but was appreciably decreased upon Zn supplementation. In addition, the uptakes of (14) C-lysine, (14) C-leucine, and (14) C-aspartic acid were also found to be elevated following Al exposure but were decreased after Zn treatment. Al treatment also caused alterations in the neurohistoarchitecture of the brain, which were improved after Zn coadministration. Therefore, the present study suggests that Zn provides protection against Al-induced neurotoxicity by regulating glucose and amino acid uptake in rats, indicating that Zn could be a potential candidate for the treatment of various neurodegenerative disorders.