Antidiabetic and pancreas-protective effects of zinc threoninate chelate in diabetic rats may be associated with its antioxidative stress ability

The Solute Carrier Superfamily as Therapeutic Targets in Pancreatic Ductal Adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC), a challenging and malignant cancer, primarily originates from the exocrine cells of the pancreas. The superfamily of solute carrier (SLC) transporters, consisting of more than 450 proteins divided into 65 families, is integral to various cellular processes and represents a promising target in precision oncology. As therapeutic targets, SLC transporters are explored through an integrative analysis.

MATERIALS AND METHODS

The expression profiles of SLCs were systematically analyzed using mRNA data from The Cancer Genome Atlas (TCGA) and protein data from the Human Protein Atlas (HPA). Survival analysis was examined to evaluate the prognostic significance of SLC transporters for overall survival (OS) and disease-specific survival (DSS). Genetic alterations were examined using cBioPortal, while structural studies were performed with AlphaFold and AlphaMissense to predict functional impacts. Furthermore, Gene Set Enrichment Analysis (GSEA) was carried out to identify oncogenic pathways linked to SLC transporter expression.

RESULTS

SLC transporters were significantly upregulated in tumors relative to normal tissues. Higher expression levels of SLC39A10 (HR = 1.89, p = 0.0026), SLC22B5 (HR = 1.84, p = 0.0042), SLC55A2 (HR = 2.15, p = 0.00023), and SLC30A6 (HR = 1.90, p = 0.003) were strongly associated with unfavorable OS, highlighting their connection to poor prognosis in PDAC. GSEA highlighted that these four transporters are significantly involved in key oncogenic pathways, such as epithelial-mesenchymal transition (EMT), TNF-α signaling, and angiogenesis.

CONCLUSIONS

The study identifies four SLCs as therapeutic targets in PDAC, highlighting their crucial role in essential metabolic pathways. These findings lay the groundwork for developing next-generation metabolic anti-cancer treatment to improve survival for PDAC patients.

Relationship Between Zinc, Selenium, and Magnesium Status and Markers of Metabolically Healthy and Unhealthy Obesity Phenotypes

Our objective was to investigate the relationship between zinc, selenium, and magnesium status and markers of metabolically healthy and unhealthy obesity phenotypes. This was a cross-sectional study with 140 women: metabolically healthy obese women (n = 35), metabolically unhealthy obese women (n = 28), and normal-weight women (n = 77). We have calculated the body mass index, waist-hip ratio, waist-height ratio and some adiposity indices. Additionally, we evaluated endocrine-metabolic parameters and estimated the dietary intake of energy, macronutrients, zinc, selenium, and magnesium. The mineral concentrations in plasma, erythrocytes, and urine were assessed. In obese patients, there was a significant decrease in dietary zinc, selenium, and magnesium intake per kilogram of body weight, as well as lower mineral concentrations in both plasma and erythrocytes. Additionally, these patients exhibited higher urinary mineral levels compared to the control group, regardless of whether they had healthy or unhealthy phenotypes. We observed a significant correlation between deficiencies in zinc, selenium, and magnesium and obesity-associated metabolic disorders, including dyslipidemias and redox status disturbances. This study highlights a connection between deficiencies in zinc, selenium, and magnesium and metabolic disorders linked to obesity, including dyslipidemias, alterations in redox status, and thyroid hormonal dysfunction.

The Link between Trace Metal Elements and Glucose Metabolism: Evidence from Zinc, Copper, Iron, and Manganese-Mediated Metabolic Regulation

Trace metal elements are of vital importance for fundamental biological processes. They function in various metabolic pathways after the long evolution of living organisms. Glucose is considered to be one of the main sources of biological energy that supports biological activities, and its metabolism is tightly regulated by trace metal elements such as iron, zinc, copper, and manganese. However, there is still a lack of understanding of the regulation of glucose metabolism by trace metal elements. In particular, the underlying mechanism of action remains to be elucidated. In this review, we summarize the current concepts and progress linking trace metal elements and glucose metabolism, particularly for the trace metal elements zinc, copper, manganese, and iron.

Effect of zinc supplementation in the management of type 2 diabetes: A grading of recommendations assessment, development, and evaluation-assessed, dose-response meta-analysis of randomized controlled trials

The question of whether zinc supplementation may improve cardio-metabolic health in patients with type 2 diabetes mellitus (T2DM) remains controversial and require further evaluation. This study aimed to summarize the effectiveness of oral zinc supplementation in improving cardio-metabolic risk markers in people with T2DM. We searched PubMed, Scopus, and Web of Science from inception to April 2023, for randomized controlled trials (RCTs). RCTs of type 2 diabetic adults (aged ≥18 years) comparing zinc supplementation with placebo were included. We excluded studies if not randomized, involved co-supplementation, and were conducted in children or pregnant women. Glycemic indices, lipid profiles, blood pressure, anthropometric measure, c-reactive protein (CRP), creatinine, and serum zinc were extracted. Certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methods. We used a random-effect model to perform the dose-response analysis. Effect sizes were presented as mean difference (MD) and 95% confidence interval (CI). 22 studies (n = 1442 participants) were included. The certainty of the evidence was rated as moderate to high. Zinc supplementation significantly reduced glycemic indices: including two-hour postprandial glucose (2hpp) (mean difference (MD): -34.34 mg/dl; 95%CI: -51.61∼ -17.07), fast blood sugar (FBS) (MD: -23.32 mg/dl; 95% CI: -33.81∼ -12.83), and hemoglobin A1c (HbA1c) (MD: -0.47; 95% CI: -0.71∼ -0.23). Zinc had a favorable effect on lipid profiles low-density lipoprotein (LDL) (MD: -10.76 mg/dl; CI: -17.79∼-3.73), triglyceride (TG) (MD: -18.23 mg/dl; CI: -32.81∼-3.65), total cholesterol (TC) (MD: -12.74 mg/dl; CI: -21.68∼-3.80), VLDL (MD: -5.39 mg/dl; CI: -7.35∼-3.43) and high-density lipoprotein (HDL) (MD: 4.04 mg/dl; CI: 0.96 ∼ 7.12). Systolic blood pressure (SBP) (MD): -3.64 mmHg; 95% CI: -6.77∼ -0.52), weight (MD: 1.00 kg; 95% CI: 0.34∼1.66), CRP (MD: -3.37 mg/l, 95% CI: -4.05∼ -2.70), and serum zinc (MD: 15.38 µg/dl; 95% CI: 10.74∼ 20.02) changed to a statistically significant extent with zinc supplementation. There was also a linear association between additional 10 mg/d zinc treatment with FBS, HbA1c, HDL, LDL, TG, TC, and serum zinc. A non-linear dose-response gradient was seen for FBS, HDL, and SBP (p < 0.05). Egger's test showed no substantial publication bias. Our findings strongly suggest a potential beneficial effect of zinc supplementation on type 2 diabetic patients. Further high-quality research is needed to determine the optimal form, dosage, and duration of zinc supplementation for this population.

Comparison of Zinc Sulfate and Zinc Threonine Based on Zn Bioavailability and Performance of Broiler Chicks

The purpose of this study was to compare zinc sulfate and zinc threonine chelate based on Zn bioavailability and performance of broiler chicks. The study was conducted in a completely randomized design with 256 day-old Ross 308 chicks and eight treatments including control treatment (no zinc supplementation), three levels of zinc sulfate and zinc threonine chelate (40, 80, and 120 mg zinc per kg feed), and a common commercial chelate (Bioplex Zn®) supply 40 mg zinc per kg feed. The results of total period showed that threonine chelate group had the highest live weight compared with other treatments and lowest feed conversion ratio belonged to 80 and 120 ppm of zinc threonine chelate (p < 0.05). Zinc threonine chelate and commercial chelate treatments had the lowest cholesterol and LDL levels compared with other treatments (p < 0.05). Zinc chelate threonine which contains 80 and 120 ppm of zinc had the highest HDL and superoxide dismutase enzymes and the lowest heterophile to lymphocyte ratio compared with other treatments (p < 0.05). Relative bioavailability of zinc threonine to zinc sulfate based on body weight, feed conversion ratio, cholesterol, LDL, HDL, superoxide dismutase enzyme, ash, and zinc content in tibia were 418.75, 173.91, 131.38, 159.43, 278.63, 193.45, 156.46, and 117.65%, respectively. According to the results of broiler performance and other traits measured in this study, it seems that the use of 80 ppm of zinc threonine chelate in the broiler diet is recommended in comparison with zinc sulfate levels and other threonine chelate levels.

Zinc enhances carnosine inhibitory effect against structural and functional age-related protein alterations in an albumin glycoxidation model

Age-related complications including protein alterations seen in diabetes and Alzheimer's disease are a major issue due to their accumulation and deleterious effects. This report aims to investigate the effect of zinc supplementation on the anti-glycoxidation activity of carnosine on the in vitro model of albumin-based protein modification. Besides, the therapeutic effect of this combination was tested through the addition of the molecules in tandem (co-treatment) or post initiation (post-treatment) of the protein modification process. Glycation was induced via the addition of glucose to which carnosine (5 mM) alone or with various zinc concentrations (125, 250, and 500 μM) were added either at 0 h or 24 h post-glycation induction. On the other hand, protein oxidation was induced using chloramine T (20 mM) and treated in the same way with carnosine and zinc. The different markers of glycation (advanced glycation end products (AGEs), dityrosine, and beta-sheet formation (aggregation)) and oxidation (AOPP, advanced oxidation protein products) were estimated via fluorescence and colorimetric assays. Zinc addition induced a significant enhancement of carnosine activity by reducing albumin modification that outperformed aminoguanidine both in the co- and post-treatment protocols. Zinc demonstrated a supplementary effect in combination with carnosine highlighting its potential in the protection against age-related protein modifications processes such as the ones found in diabetes.

Zinc Supplementation and Body Weight: A Systematic Review and Dose-Response Meta-analysis of Randomized Controlled Trials

The aim of this study was to determine the effect of zinc supplementation on anthropometric measures. In this systematic review and dose-response meta-analysis, we searched PubMed, Scopus, ISI Web of Science, and the Cochrane Library from database inception to August 2018 for relevant randomized controlled trials. Mean differences and SDs for each outcome were pooled using a random-effects model. Furthermore, a dose-response analysis for zinc dosage was performed using a fractional polynomial model. Quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. Twenty-seven trials (n = 1438 participants) were included in the meta-analysis. There were no significant changes in anthropometric measures after zinc supplementation in the overall analysis. However, subgroup analyses revealed that zinc supplementation increased body weight in individuals undergoing hemodialysis (HD) [3 trials, n = 154 participants; weighted mean difference (WMD) = 1.02 kg; 95% CI: 0.38, 1.65 kg; P = 0.002; I2 = 11.4%] and decreased body weight in subjects who are overweight/obese but otherwise healthy (5 trials, n = 245 participants; WMD = -0.55 kg; 95% CI: -1.06, -0.04 kg; P = 0.03; I2 = 31.5%). Dose-response analyses revealed a significant nonlinear effect of supplementation dosage on BMI (P = 0.001). Our data suggest that zinc supplementation increases body weight in patients undergoing HD and decreases body weight in individuals who are overweight/obese but otherwise healthy, although after normalization for study duration, the association observed in subjects who are overweight/obese disappeared. Although more high-quality studies are needed to reach a definitive conclusion, our study supports the view that zinc may be associated with body weight.

The status of zinc in type 2 diabetic patients and its association with glycemic control

BACKGROUND

Zinc (Zn) is a trace element that carries antioxidant properties. Deficiency of Zn increases oxidative stress, especially in diabetes. The objective of this study was to assess the relationship between the level of Zn and glycemic control in type 2 diabetes.

MATERIALS AND METHODS

A cross-sectional study was carried out in the Department of Medicine at King Abdullah bin Abdulaziz University Hospital, Riyadh, Saudi Arabia, from March 2018 to September 2018. A total of 440 participants were included in the study; 252 of these had type 2 diabetes and 188 were controls. All participants had laboratory investigations including fasting blood sugar (FBS), glycosylated hemoglobin, and lipid profile and Zn levels. These two groups (diabetics and controls) were further divided into Zn deficient group and normal Zn group according to their Zn levels. Data were analyzed by using SPSS software.

RESULTS

The mean Zn level was 11.7 + 1.5 in the control group, whereas it was significantly low (9.3 + 1.6) in the diabetic group (P < 0.001). Zn deficiency in the control group was only 6.4%, while in the diabetic group, it was 67.9%, (P ≤ 0.001). The mean ages for the low Zn group and normal Zn group were 40.9 + 12.5 and 37.5 + 10.1, respectively, and the Zn deficient group was higher in age (P = 0.003). There was no significant statistical difference between genders regarding Zn deficiency. Obesity was associated with significantly low Zn levels (P = 0.016). The serum Zn level was significantly negatively associated with FBS and glycated hemoglobin in diabetic participants (P < 0.001).

CONCLUSION

Diabetic patients have Zn deficiency compared to normal individuals and poor glycemic control is associated with low Zn levels.

The effect of zinc supplementation in pre-diabetes: A protocol for systematic review and meta-analysis

BACKGROUND

The number of people with diabetes and pre-diabetes is growing exponentially. Human studies have shown that zinc supplementation is beneficial for pre-diabetes. However, owing to the low quality, small sample size, and methodological heterogeneity of these studies, this conclusion is not convincing. Consequently, in order to determine whether zinc supplementation is effective and safe in pre-diabetic patients, it is necessary to conduct a meta-analysis of high-quality clinical trials.

METHODS

We will retrieve MEDLINE (PubMed), EMBASE, the Web of Science, Cochrane Library, and the ClinicalTrials.gov website without restriction on language. Randomized controlled trials (RCTs) of Zinc supplementation for adult patients with pre-diabetes will be searched in multiple databases from inception to October 2020. The primary outcome of the meta-analysis is the HbA1c. The secondary outcomes include the fasting blood glucose (FBG), fasting insulin (FINS), homeostasis model assessment of insulin resistance (HOMA-IR), and quantitative insulin sensitivity check index (QUICKI). Two assessors will utilize the Cochrane Collaboration's risk of bias tool to evaluate the RCTs and all statistical data will be analyzed by using the Review Manage software V5.3.0.

RESULTS

This study will provide high-quality synthesis of effectiveness and safety of zinc supplementation for pre-diabetes.

CONCLUSION

This systematic review and meta-analysis will provide the available evidence to assess whether the zinc supplementation is beneficial to glucose control and insulin resistance in patients with pre-diabetes.

PROSPERO REGISTRATION NUMBER

CRD 42018095724.

Zinc supplementation reduces diet-induced obesity and improves insulin sensitivity in rats

Rates of obesity have been growing at alarming rates, compromising the health of the world population. Thus, the search for interventions that address the metabolic repercussions of obesity are necessary. Here we evaluated the metabolic and antioxidant effects of zinc and branched-chain amino acids (BCAA) supplementation on obese rats. Male Wistar rats were fed either a high-fat/high-fructose diet (HFD) or a standard diet (SD) for 19 weeks. From the fifteenth week until the end of the experiment, HFD- and SD-fed rats received zinc (6 mg/kg) or BCAA (750 mg/kg) supplementation. Body weight, abdominal fat, lipid profile, blood glucose, insulin, leptin, and hepatic transaminases were evaluated. In the liver, superoxide dismutase and catalase activities and lipid peroxidation were also analyzed. HFD-fed animals showed increased weight gain, abdominal fat pad, plasma insulin, leptin, and triglycerides levels in comparison with SD-fed rats. Zinc supplementation reduced all these parameters, suggesting a beneficial role for the treatment of obesity. BCAA, on the other hand, did not show any beneficial effect. Liver antioxidant enzymes and hepatic transaminases plasma levels did not change among groups. Lipid peroxidation was higher in HFD-fed rats and was not reverted by zinc or BCAA supplementation. In conclusion, zinc supplementation may be a useful strategy for the treatment of the metabolic dysfunction associated with obesity.

Effect of zinc supplementation on triglyceride and malondialdehyde levels: study on diabetic Wistar rats induced with streptozotocin

Background: Diabetes mellitus is associated with increased blood glucose and triglyceride levels, which can lead to an oxidative stress. Zinc (Zn) is a micronutrient that has antioxidant properties and involved in lipid and glucose metabolism. This study aimed to evaluate the effect of zinc on the levels of fasting blood glucose (FBG), triglycerides (TG), and malondialdehyde (MDA) in male diabetic Rattus norvegicus Wistar rats.Methods: Diabetes was induced by intraperitoneal (i.p.) injection of 40 mg/kg BW streptozotocin (STZ) and confirmed by FBG level higher than 200 mg/dL after 2 weeks. The rats were randomly divided into three groups: control group (STZ), treatment I (STZ + zinc 5 mg/kg BW), and treatment II (STZ + zinc 10 mg/kg BW). Zinc was administered by oral gavage for 30 days. At the end of the experiment, levels of FBG, TG, and MDA were measured. Data were analyzed using paired t-test or Wilcoxon test as appropriate.Results: Supplementation of 5 mg/kg zinc significantly decreased the levels of FBG (pre-intervention: 328.95±70.90 mg/dL, post-intervention: 144.35±34.27 mg/dL, p<0.05), TG (pre-intervention: 252.48±26.30 mg/dL, post-intervention: 147.90±12.18 mg/dL, p<0.05), and MDA (pre-intervention: 12.11±6.46 nm/mL, post-intervention: 4.75±2.34 nm/mL, p<0.05). Moreover, supplementation of 10 mg/kg zinc decreased the levels of TG (pre-intervention: 275.62±56.25nm/mL, post-intervention: 165.58±22.63 nm/mL, p<0.05) and MDA (pre-intervention: 13.08±6.60 nm/mL, post-intervention: 5.08±2.40 nm/mL, p<0.05).Conclusion: Supplementation of zinc significantly reduced the levels of FBG, TG, and MDA in diabetic rats.

Effect of Zinc Supplementation on Maintenance Hemodialysis Patients: A Systematic Review and Meta-Analysis of 15 Randomized Controlled Trials

We aimed to examine the effects of zinc supplementation on nutritional status, lipid profile, and antioxidant and anti-inflammatory therapies in maintenance hemodialysis (MHD) patients. We performed a systematic review and meta-analysis of randomized, controlled clinical trials of zinc supplementation. Metaregression analyses were utilized to determine the cause of discrepancy. Begg and Egger tests were performed to assess publication bias. Subgroup analysis was utilized to investigate the effects of zinc supplementation in certain conditions. In the crude pooled results, we found that zinc supplementation resulted in higher serum zinc levels (weighted mean difference [WMD] = 28.489; P < 0.001), higher dietary protein intake (WMD = 8.012; P < 0.001), higher superoxide dismutase levels (WMD = 357.568; P = 0.001), and lower levels of C-reactive protein (WMD = −8.618; P = 0.015) and malondialdehyde (WMD = −1.275; P < 0.001). The results showed no differences in lipid profile. In the metaregression analysis, we found that serum zinc levels correlated positively with intervention time (β = 0.272; P = 0.042) and varied greatly by ethnicity (P = 0.023). Results from Begg and Egger tests showed that there was no significant bias in our meta-analysis (P > 0.1). Results of subgroup analysis supported the above results. Our analysis shows that zinc supplementation may benefit the nutritional status of MHD patients and show a time-effect relationship.

Investigation of lipid peroxidation and antiapoptotic effects of zinc aganist liver damage in diabetic rats

Several mechanisms for the pathogenesis of diabetic complications have been proposed, one of which is abnormal zinc (Zn) homeostasis. Zn is necessary for proper liver function since it has important antioxidant, anti-inflammatory, and antiapoptotic properties. We aimed to investigate whether or not Zn has morphologically protective effect on diabetes-induced liver damage in rats. In addition, we have investigated the role of Zn supplementation on apoptosis, lipid peroxidation levels, and the distribution of metallothionein (MT) in diabetic liver tissue. Wistar albino rats were divided into four groups: control, Zn, diabetic, and Zn-diabetic group. Experimental diabetes was induced by a single-dose streptozotocin intraperitoneally and Zn was administrated via gastric gavage tube for 6 weeks. MT expressions were showed with immunohistochemical staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was used for apoptosis. Also, Zn, MT, and malondialdehyde (MDA) levels were determined in liver of rats. MDA levels of the Zn-supplemented diabetic group was less than the diabetic group though MT levels were increased. The number of apoptotic cells per unit area was found to be significantly decreased in this group. In the Zn-supplemented diabetic group, fibrotic tissue density and the collagen tissue density were observed less than the diabetic group. MT immunoreactivity was observed less in Zn-supplemented diabetic group. In conculusion, the present study indicated that Zn has a potential in preventing or even repairing effect against diabetic damage of the liver cells by increasing expression of MT and by reducing the apoptotic cell death and the oxidative stress.

Intracellular zinc in insulin secretion and action: a determinant of diabetes risk?

Zinc is an important micronutrient, essential in the diet to avoid a variety of conditions associated with malnutrition such as diarrhoea and alopecia. Lowered circulating levels of zinc are also found in diabetes mellitus, a condition which affects one in twelve of the adult population and whose treatments consume approximately 10 % of healthcare budgets. Zn2+ ions are essential for a huge range of cellular functions and, in the specialised pancreatic β-cell, for the storage of insulin within the secretory granule. Correspondingly, genetic variants in the SLC30A8 gene, which encodes the diabetes-associated granule-resident Zn2+ transporter ZnT8, are associated with an altered risk of type 2 diabetes. Here, we focus on (i) recent advances in measuring free zinc concentrations dynamically in subcellular compartments, and (ii) studies dissecting the role of intracellular zinc in the control of glucose homeostasis in vitro and in vivo. We discuss the effects on insulin secretion and action of deleting or over-expressing Slc30a8 highly selectively in the pancreatic β-cell, and the role of zinc in insulin signalling. While modulated by genetic variability, healthy levels of dietary zinc, and hence normal cellular zinc homeostasis, are likely to play an important role in the proper release and action of insulin to maintain glucose homeostasis and lower diabetes risk.