Effect of different dietary zinc levels on hepatic antioxidant and micronutrients indices under oxidative stress conditions

Targeting the NF-κB p65/Bcl-2 signaling pathway in hepatic cellular carcinoma using radiation assisted synthesis of zinc nanoparticles coated with naturally isolated gallic acid

PURPOSE

Oral diethylnitrosamine (DEN) is a known hepatocarcinogen that damages the liver and causes cancer. DEN damages the liver through reactive oxygen species-mediated inflammation and biological process regulation.

MATERIALS AND METHODS

Gallic acid-coated zinc oxide nanoparticles (Zn-GANPs) were made from zinc oxide (ZnO) synthesized by irradiation dose of 50 kGy utilizing a Co-60 γ-ray source chamber with a dose rate of 0.83 kGy/h and gallic acid from pomegranate peel. UV-visible (UV) spectrophotometry verified Zn-GANP synthesis. TEM, DLS, and FTIR were utilized to investigate ZnO-NPs' characteristics. Rats were orally exposed to DEN for 8 weeks at 20 mg/kg five times per week, followed by intraperitoneal injection of Zn-GANPs at 20 mg/kg for 5 weeks. Using oxidative stress, anti-inflammatory, liver function, histologic, apoptotic, and cell cycle parameters for evaluating Zn-GANPs treatment.

RESULTS

DEN exposure elevated inflammatory markers (AFP and NF-κB p65), transaminases (AST, ALT), γ-GT, globulin, and total bilirubin, with reduced protein and albumin levels. It also increased MDA levels, oxidative liver cell damage, and Bcl-2, while decreasing caspase-3 and antioxidants like GSH, and CAT. Zn-GANPs significantly mitigated these effects and lowered lipid peroxidation, AST, ALT, and γ-GT levels, significantly increased CAT and GSH levels (p<0.05). Zn-GANPs caused S and G2/M cell cycle arrest and G0/G1 apoptosis. These results were associated with higher caspase-3 levels and lower Bcl-2 and TGF-β1 levels. Zn-GANPs enhance and restore the histology and ultrastructure of the liver in DEN-induced rats.

CONCLUSION

The data imply that Zn-GANPs may prevent and treat DEN-induced liver damage and carcinogenesis.

The Biochemistry and Effectiveness of Antioxidants in Food, Fruits, and Marine Algae

It is more effective to maintain good health than to regain it after losing it. This work focuses on the biochemical defense mechanisms against free radicals and their role in building and maintaining antioxidant shields, aiming to show how to balance, as much as possible, the situations in which we are exposed to free radicals. To achieve this aim, foods, fruits, and marine algae with a high antioxidant content should constitute the basis of nutritional elements, since natural products are known to have significantly greater assimilation efficiency. This review also gives the perspective in which the use of antioxidants can extend the life of food products, by protecting them from damage caused by oxidation as well as their use as food additives.

Protective Effect of Vitamin C and Zinc as an Antioxidant Against Chemotherapy-Induced Male Reproductive Toxicity

Treatment with anticancer drugs such as cyclophosphamide can harm the male reproductive system. Vitamin C and zinc are micronutrients with antioxidant activity and are the essential components of semen. Therefore, this study aimed to evaluate whether cyclophosphamide-exposed mice can recover from fertility with vitamin C and zinc therapy.

In this experimental study, fifty male mice were divided into five groups. Groups 1-4 received cyclophosphamide (100 mg/kg, once a week for eight weeks). Also, group 2 received zinc (200 mg/kg), group 3 received vitamin C (300 mg/kg), group 4 received zinc and vitamin C (200 mg/kg and 300 mg/kg, respectively), five times per week for eight weeks, and group 5 received normal saline once a week and water five days a week for eight weeks. The data collected were statistically analyzed using SPSS 22.

Results showed a significant increase in mount latency and a significant decrease in the number of sperms in the cyclophosphamide group compared to the control group. However, mount latency has been significantly decreased in mice treated with cyclophosphamide plus zinc compared to the cyclophosphamide group. The study also showed that the sperm count in the group that received cyclophosphamide and zinc had been increased compared to the cyclophosphamide group; the other treatments have decreased mount latency and increased the sperm count compared to the group treated with cyclophosphamide but not significantly. The Tubule Differentiation Index showed an increase in the cyclophosphamide-Zinc-Vitamin C group in comparison with the cyclophosphamide group.

The current study showed that zinc could improve cyclophosphamide-induced toxicity of the reproductive system in male mice.

The Hepatoprotective Effects of Zinc Glycine on Liver Injury in Meat Duck Through Alleviating Hepatic Lipid Deposition and Inflammation

Dietary zinc status was recently approved to exert a powerful influence on liver health, and zinc deficiency results in hepatic injury caused by fat deposition, inflammation, and oxidant stress, but the effect of zinc on hepatic lipid metabolism and liver injury in meat duck has not been well defined. To determine the hepatoprotective effects of graded zinc glycine in meat ducks. A total of 384 1-day-old male meat ducks were subjected to 5 weeks feeding program with three experimental diets: (1) low-zinc diet, (2) adequate-zinc diet, and (3) high-zinc diet. Blood and liver samples were collected for biochemical analysis, gene expression analysis, and histopathological study. Diet with low zinc increased hepatic lipid content and triglyceride concentration. Meat ducks fed low-zinc diet exhibited considerably increased serum alanine aminotransferase (ALT) activity than birds fed other diets among all groups (P < 0.05). Low zinc administration also notably induced hepatocyte apoptosis and stimulated hepatic inflammatory gene expression. Adequate or high zinc supplementation increased hepatic zinc level, reduced hepatic lipid deposition and hepatosomatic indices through suppressing the expression of lipogenic genes including fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) (P < 0.05), and upregulated the mRNA expression of both fatty acid secretion and β-oxidation, including carnitine palmitoyltransferase 1a (Cpt1a), peroxisome proliferator-activated receptor (PPAR)α, and apolipoprotein B (ApoB) (P < 0.05). Dietary zinc addition also declined hepatic mRNA expression of interleukin (IL)-1β and IL-6 (P < 0.05). Furthermore, diets with adequate or high zinc significantly decreased serum ALT activity and hepatocyte apoptosis. These data revealed that supplementing adequate- or high-zinc glycine efficiently protects liver injury by attenuating lipid deposition and hepatic inflammation.

Study on the synergistic protective effect of Lycium barbarum L. polysaccharides and zinc sulfate on chronic alcoholic liver injury in rats

Both Lycium barbarum L. polysaccharides (LBP) and zinc have protective effects on liver injuries. In this paper, LBP and ZnSO4 were combined to study the effects on the prevention of alcoholic liver injury. The rats were divided into six groups, the normal group, alcohol group, zinc sulfate group, LBP group, low-dose group of ZnSO4, and high-dose group of ZnSO4 and LBP, used to explore the impact of LBP and ZnSO4 complex on liver lipid metabolism of alcohol, alcohol-metabolizing enzymes, oxidative damage, and inflammation of the liver. The experimental model was established by gavage treatment, observation, and determination of indexes of rats. The results showed that the combination of LBP and ZnSO4 could significantly decrease the levels of triglyceride (TG), total cholesterol (TC), tumor necrosis factor-α(TNF-ɑ), malondialdehyde (MDA), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and the activity of enzyme subtype 2E1 (CYP2E1). It also significantly increased the activities of total superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione peptide (GSH), and alcohol dehydrogenase, effectively improved the liver tissue lesion. What is more, the combination of LBP and ZnSO4 had a synergistic effect on the remission of alcoholic fatty liver, and alleviated chronic alcoholic liver injury by promoting lipid metabolism, inhibiting oxidative stress, controlling inflammatory responses, and regulating the expression and activity of alcohol-metabolizing enzymes in rats.

Effect of zinc addition on the immune response and production performance of broilers: a meta-analysis

Objective

This study performed a meta-analysis of published trials to determine the effects of zinc on the immune response and production performance of broilers.

Methods

A database was built from published literature regarding the addition of zinc forms or doses and their relation to the immune response and production performance of broilers. Different doses or forms of zinc were identified in the database. The recorded parameters were related to the immune response and production performance. The database contained a total of 323 data points from 41 studies that met the criteria. Then, the data were processed for a meta-analysis using a mixed model methodology. The doses or different forms of zinc were considered fixed effects, different studies were treated as random effects, and p-values were used as the model statistics.

Results

An increase in zinc dose increased (p<0.05) pancreas metallothionein (MT) and zinc concentrations in the plasma, tibia and meat, all in quadratic patterns, but linearly decreased (p<0.05) the heterophil/lymphocyte (H/L) ratio. Regarding the different zinc forms, both inorganic and organic zinc increased (p<0.05) the zinc concentrations in the plasma and tibia, the calcium and phosphorus contents in the tibia, and the antioxidant activity of superoxide dismutase in meat as compared to control. An increase in zinc dose increased average daily gain (ADG) and decreased feed conversion ratio (FCR) following a quadratic pattern (p<0.05). Inorganic and organic zinc decreased (p<0.05) FCR and H/L ratio than that of control, but these two forms were similar for these parameters.

Conclusion

Zinc addition has a positive impact on immunity and broiler production. Zinc can suppress stress and inhibit the occurrence of lipid peroxidation in broilers, and it can also improve ADG, FCR, and the quality of broiler carcasses.

Protective Effect of Zinc Supplementation on Renal Ischemia/Reperfusion Injury in Rat: Gender-related Difference

Background:

Zinc (Zn) knows as essential microelement which prevents oxidative stress. The effect of Zn supplement on renal function parameters in rats subjected to renal ischemia-reperfusion (IR) injury was investigated.

Methods:

Male and female rats were subjected to renal IR with and without Zn sulfate (10 mg/kg/day for 5 days) supplementation. The kidney function markers and histology findings in Zn-treated group were compared with sham and control groups.

Results:

The serum levels of blood urea nitrogen and creatinine (Cr) and kidney tissue damage score were increased significantly after renal injury (P < 0.05) gender dependently, but no alterations were observed for these markers in Zn-treated animals after renal IR injury. Cr clearance was significantly different between genders (P < 0.05); however, Zn supplementation increased the Cr clearance and kidney nitrite level significantly in male rats (P < 0.05). Zn also increased urine flow in female (P < 0.05), but it did not alter urine load of Na (U_NaV) and percentage of Na excretion (E_Na%).

Conclusions:

Zn may improve renal function after IR injury gender dependently.

Effects of dietary lipid-coated zinc on the antioxidant defense system in the small intestine and liver of piglets

The purpose of the study was to investigate the effects of lipid-coated ZnO (LCZ) and the level of LCZ compared with ordinary zinc oxide (ZnO) on antioxidant defense system in the intestine and liver of piglets. A total of forty piglets (n=8) were fed a diet supplemented with 100 ppm Zn with ZnO (ZnO-1), 2,500 ppm Zn with ZnO (ZnO-2), 100 ppm Zn as LCZ (LCZ-1), 200 ppm Zn as LCZ (LCZ-2), or 400 ppm Zn as LCZ (LCZ-3) for 14-d, respectively. The LCZ-3 group resulted in higher (P<0.05) mRNA expressions and activities of CuZn-superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT), and glutathione S-transferase (GST) in jejunal mucosa compared with the ZnO-1 and LCZ-1 groups, while no difference was observed in the mRNA level of antioxidant genes between the ZnO-1 and ZnO-2 groups. Within the LCZ groups, the LCZ level linearly and quadratically (P<0.01) increased antioxidant enzymes in the jejunum. The maximum response of jejunal antioxidant enzymes to Zn supplementation was achieved by 400 ppm of LCZ. Hepatic mRNA expression of antioxidant enzymes was unaffected by Zn source and level, while hepatic SOD and GST activities were greater (P<0.05) in the LCZ-3 group than in the ZnO-1 group. No difference was observed in lipid peroxidation of the jejunum and liver and the total antioxidant power of plasma among groups. In conclusion, a supplementation with 400 ppm of LCZ resulted in a maximum increase in antioxidant enzymes, indicating that LCZ may affect antioxidant defense system more profoundly than ZnO.

Preventive effects of supplemental dietary zinc on heat-induced damage in the epididymis of boars

Hyperthermia in boars reduces growth performance and sperm production. Zinc is an essential trace element in animal nutrition. Here we investigate the effects of dietary zinc on epididymal structure and function in Bama miniature pigs treated with heat exposure and investigate approaches to improve the reproductive performance in summer. Male Bama miniature pigs (n=18; aged 6 months; bodyweight=10.79±0.06kg) were randomly allocated to 3 groups: control group (Control), heat treatment group (HT), and the diet-supplemented and heat treatment group (H+Zn). The Control and HT groups were fed with basal diet and the H+Zn group were fed with basal diet plus 1500mg/kg zinc daily. After being fed with these 2 different diets for 30 days, pigs in the HT and H+Zn groups were exposed to 5h of 40°C heat treatment for 8 days. Rectal temperature and jugular venous blood were collected 3h after onset of heat exposure on days 1, 4 and 8. Pigs were sacrificed after the termination of heat exposure. Heat treatment increased serum testosterone concentration on day 1 and 4 (P<0.01). In addition, the HT group displayed an increase in the clear cell count and a decrease in epithelium thickness in the caput epithelium (P<0.01, P<0.05), and dietary zinc protected the boars from these impairments (P<0.01, P=0.29). Evaluation of oxidative states showed that heat exposure increased the levels of malondialdehyde (MDA) and glutathione (GSH) in the epididymis (P<0.01, P<0.05), while dietary zinc reduced this elevation (P<0.01, P<0.01). Heat exposure enhanced the glucocorticoid receptor (GR) expression in the nuclei of principal and basal cells (P<0.01, P<0.01) while dietary zinc attenuated the GR immunoreactivity intensity (P<0.01, P<0.01). These results demonstrate that dietary zinc protects the epididymis from high temperature-induced impairment, alleviates oxidative stress, restores the integrity of the caput epithelium and decreases the stress response.

Effects of supplemental zinc source and level on antioxidant ability and fat metabolism-related enzymes of broilers

The objective of the present study was to investigate the effects of dietary supplemental Zinc (Zn) source and level on antioxidant ability and fat metabolism-related enzymes of broilers. Dietary treatments included the Zn-unsupplemented corn-soybean meal basal diet (control) and basal diets supplemented with 60, 120, or 180 mg Zn/kg as Zn sulfate, Zn amino acid chelate with a weak chelation strength of 6.5 quotient of formation (Q_f) (11.93% Zn) (Zn-AA W), Zn proteinate with a moderate chelation strength of 30.7 Q_f (13.27% Zn) (Zn-Pro M), or Zn proteinate with an extremely strong chelation strength of 944.0 Q_f (18.61% Zn) (Zn-Pro S). The results showed that dietary supplemental Zn increased (P < 0.01) Zn contents in the liver, breast, and thigh muscles of broilers, and up-regulated mRNA expressions of copper and Zn containing superoxide dismutase (CuZnSOD) and metallothioneins (MT) in the liver (P < 0.01) and thigh muscle (P < 0.05), and also enhanced (P < 0.05) CuZnSOD activities in the breast and thigh muscles, which exerted antioxidant ability and a decreased malondialdehyde (MDA) level in the liver (P < 0.01) and breast and thigh muscles (P < 0.05) of broilers. Furthermore, supplemental Zn increased activities of malate dehydrogenase (MDH) and lipoprotein lipase (LPL) in the abdominal fat (P < 0.05), and fatty acid synthetase (FAS) and LPL in the liver (P < 0.01), which were accompanied with up-regulation (P < 0.01) of the mRNA expressions levels of these enzymes in the abdominal fat and liver of broilers. Dietary Zn source, and an interaction between Zn source and level, had no effects on any measurements. It is concluded that dietary Zn supplementation improved Zn status and resulted in promoting antioxidant ability and activities and gene expressions of fat metabolism-related enzymes of broilers regardless of Zn source and level, and the addition of 60 mg Zn/kg to the corn-soybean meal basal diet (a total dietary Zn of approximately 90 mg/kg) was appropriate for improving the above aspects of broilers.

Zinc might prevent heat-induced hepatic injury by activating the Nrf2-antioxidant in mice

Zinc (Zn) is generally known to be an essential trace element with growth-promoting and antioxidant activities. The present study was performed to clarify the role of Zn in the livers of heat-treated mice. Eight-week-old male mice were divided into control (Con), heat treatment (HT) and heat treatment plus zinc groups (HT + Zn) and were fed diets containing 60, 60, or 300 mg/kg Zn (zinc sulfate), respectively. After 30 days of feeding on their respective diets, the control group was maintained at a controlled temperature (25 °C), whereas the HT and HT + Zn groups were exposed to an elevated ambient temperature (40-42 °C) for 2 h each day. After heat exposure for seven consecutive days, sera and liver tissues were collected. The mice in the HT group exhibited reduced liver weights and lower hepatosomatic indices. Histological findings revealed that the hepatocytes of the HT group were subjected to serious damage and exhibited irregular arrangements and nuclear pyknosis. Moreover, in the HT group, the hepatic malondialdehyde levels were significantly increased, while the serum alkaline phosphatase levels, hepatic copper/zinc-superoxide dismutase (CuZn-SOD) and glutathione peroxidase activities were significantly reduced compared to those of the control group. However, in the HT + Zn group, the histomorphology of the liver was restored, the serum aspartate aminotransferase (AST) level was significantly decreased, and the hepatic CuZn-SOD activity was significantly increased compared to the HT group. Furthermore, expressions of the hepatic Nrf2 protein and Nrf2, Keap1, and NQO1 genes in the HT + Zn group were not only higher than the HT group but also higher than the control group. Zn might alleviate heat-induced hepatic injury as revealed by restored histomorphology and AST level. Our results further suggest that Zn might exert its protective effects via the activation of the Nrf2-antioxidant pathway.

Zn(II)-curcumin protects against oxidative stress, deleterious changes in sperm parameters and histological alterations in a male mouse model of cyclophosphamide-induced reproductive damage

The poor bioavailability and stability of curcumin limit its clinical application. A novel Zn(II)-curcumin complex was synthesized and its effects against cyclophosphamide (CP)-induced reproductive damage were compared with curcumin. Oral administration of Zn(II)-curcumin significantly prevented CP-induced elevation of malondialdehyde (MDA) level and reductions in superoxide dismutase (SOD) activity and glutathione (GSH) content in mouse testis. Zn(II)-curcumin significantly ameliorated CP-induced reductions in body and reproductive organs weights. Zn(II)-curcumin dose-dependently ameliorated CP-induced reproductive system impairments, by improving sperm parameters (sperm count, viability, motility) and reducing serum testosterone and histological alterations. Compared to curcumin at the same dose, Zn(II)-curcumin more effectively alleviated CP-induced reproductive injury, leading to a reduced severity of testicular pathologic changes, lower MDA level, elevated SOD activity and GSH content, and increased sperm parameters and serum testosterone. These results suggest Zn(II)-curcumin more effectively protects against CP-induced reproductive damage than curcumin alone due to a synergistic reduction in oxidative stress.

The prevalence of zinc deficiency in patients with thalassemia in South East of iran, sistan and baluchistan province

Background:

There are different and controversial reports about zinc deficiency in patients with major thalassemia.

Objectives:

The aim of this study was to evaluate zinc status in patients with major thalassemia in Sistan and Baluchistan province, southeastern Iran.

Patients and Methods:

The study was performed in Ali Asghar Hospital, a specialized governmental hospital located in Zahedan, Iran. In this cross-sectional study, 369 patients with a history of major thalassemia for more than 5 years entered the study using convenience sampling method. Thirty-six subjects were excluded from the study based on our exclusion criteria. Zinc level was measured in all patients after 12 hours fasting using atomic absorption spectrometry method in 2012.

Results:

Of 369 cases, 333 patients were eligible and evaluated. The mean age was 15.63 ± 7.4 years. One hundred ninety two cases were male and others were female (141 cases). About 27% (90) of the cases were 5-10 years-old, 24% (80) were 10-15 years-old and 49% were older than 15 years old. Iron chelator in 65.46% was Desferrioxamine, in 28.2% was Deferasirox and in 19.5% was combination of Desferrioxamine and Deferiprone. All cases had zinc deficiency, and 98.5% had severe zinc deficiency. Others (1.5%) had mild deficiency.

Conclusions:

Our study on 333 patients with major thalassemia documented severe zinc deficiency in all cases. We had no cases with normal or increased zinc levels. It was different with other reports in the world.

Zn(II)-curcumin protects against hemorheological alterations, oxidative stress and liver injury in a rat model of acute alcoholism

Curcumin can chelate metal ions, forming metallocomplexes. We compared the effects of Zn(II)-curcumin with curcumin against hemorheological alterations, oxidative stress and liver injury in a rat model of acute alcoholism. Oral administration of Zn(II)-curcumin dose-dependently prevented the ethanol-induced elevation of serum malondialdehyde (MDA) content and reductions in glutathione level and superoxide dismutase (SOD) activity. Zn(II)-curcumin also inhibited ethanol-induced liver injury. Additionally, Zn(II)-curcumin dose-dependently inhibited hemorheological abnormalities, including the ethanol-induced elevation of whole blood viscosity, plasma viscosity, blood viscosity at corrected hematocrit (45%), erythrocyte aggregation index, erythrocyte rigidity index and hematocrit. Compared to curcumin at the same dose, Zn(II)-curcumin more effectively elevated SOD activity, ameliorated liver injury and improved hemorheological variables. These results suggest that Zn(II)-curcumin protected the rats from ethanol-induced liver injury and hemorheological abnormalities via the synergistic effect of curcumin and zinc.

Psychological stress induced zinc accumulation and up-regulation of ZIP14 and metallothionein in rat liver

Background

Zinc is necessary for normal liver function; and vice versa, the liver plays a central role in zinc homeostasis. The aim of present study is to assess the effects of repeated psychological stress (PS) on the zinc metabolism and related mechanism involved in zinc homeostasis in rat liver.

Methods

In present study, we used communication box to create PS model and investigated the serum corticosterone (CORT), zinc level in serum and liver, liver metallothionein (MT) content and ZRT/IRT-like Protein 14 (ZIP14) mRNA expression.

Results

The results showed that the serum CORT level increased and serum zinc level decreased significantly after 7 d and 14 d PS treatment. Meanwhile, zinc and MT contents in liver were elevated after 14 d PS exposure, while those in 7 d PS exposure group did not change. ZIP14 mRNA was expressed markedly at 7 d after the onset of PS, while Zip14 mRNA expression in the liver after 14 d PS exposure reached normal level compared with control group.

Conclusions

The results suggest that PS exposure could induce hypozincemia, which might be related to liver zinc accumulation because of high level of MT through glucocorticoid-mediated MT synthesis and ZIP14 expression induced by interleukin-6.

Panax ginseng reduces oxidative stress and restores antioxidant capacity in aged rats

Nutritional antioxidants interact with cells in an active mode, including retrieving and sparing one another, to diminish oxidative stress. However, the intracellular balance of prooxidants and antioxidants becomes unbalanced, favoring prooxidants during the aging process. One hypothesis is that an aging-associated increase in oxidative stress is the primary cause of aging. Hence, the research hypothesis for this study is that Korean red ginseng reduces oxidative stress in vivo. Therefore, we investigated the efficacy of Korean red ginseng water extract (GWE) in reducing aging-associated oxidative stress by measuring lipid peroxidation and antioxidant levels in older rats compared with young rats. We observed a significant increase in the markers for oxidative damage (eg, lipid peroxidation) and markers for vital organ damage (eg, aspartate aminotransferase, alanine aminotransferase, urea, and creatinine levels) in aged rats. The oxidative damage was accompanied by a significant decrease in enzymatic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione-S-transferase, and nonenzymatic antioxidants such as reduced glutathione, vitamin E, and vitamin C. Aged rats fed a diet supplemented with Korean red ginseng water extract had significantly less oxidative damage, possibly by enhancing the enzymatic and nonenzymatic antioxidants status. Our data suggest that consumption of Korean red ginseng reduces lipid peroxidation and restores antioxidant capacity by suppressing oxidative stress in rats.

Dietary nicotinic acid supplementation improves hepatic zinc uptake and offers hepatoprotection against oxidative damage

We examined the effect of dietary nicotinic acid (NA) variations before and after oxidative stress (OS) treatment on the antioxidant defence system, function and morphology of the liver along with Zn status in rats. OS was generated by three intraperitoneal injections of tert-butyl hydroperoxide in the first week for the pre-exposure group and in the third week for the post-exposure group, respectively. These groups were further divided into subgroups and fed on a diet with marginally deficient Zn (10 mg Zn/kg diet) and NA variations as NA deficient, normal and excess with 10, 30 and 1000 mg NA/kg diet, respectively. Aspartate aminotransferase and alanine aminotransferase levels were elevated in rats with OS coupled with the Zn- and NA-deficient diet, which decreased towards normal with excess dietary NA. Excess NA supplementation in the OS pre-exposure group resulted in nearly preserved hepatic architecture with normal hepatocytes, whereas maximum tissue destruction was evident in the post-exposure group with NA deficiency. Dose-dependent improvement in the antioxidant defence system, enhanced reduced glutathione levels, lowered lipid peroxidation and higher hepatic Zn levels were observed with NA supplementation. The effect was more prominent in the pre-exposure group. In conclusion, dietary NA supplementation improves hepatic Zn uptake and results in hepatoprotection against OS-induced damage in rats.

Trace elements in glucometabolic disorders: an update

Many trace elements, among which metals, are indispensable for proper functioning of a myriad of biochemical reactions, more particularly as enzyme cofactors. This is particularly true for the vast set of processes involved in regulation of glucose homeostasis, being it in glucose metabolism itself or in hormonal control, especially insulin. The role and importance of trace elements such as chromium, zinc, selenium, lithium and vanadium are much less evident and subjected to chronic debate. This review updates our actual knowledge concerning these five trace elements. A careful survey of the literature shows that while theoretical postulates from some key roles of these elements had led to real hopes for therapy of insulin resistance and diabetes, the limited experience based on available data indicates that beneficial effects and use of most of them are subjected to caution, given the narrow window between safe and unsafe doses. Clear therapeutic benefit in these pathologies is presently doubtful but some data indicate that these metals may have a clinical interest in patients presenting deficiencies in individual metal levels. The same holds true for an association of some trace elements such as chromium or zinc with oral antidiabetics. However, this area is essentially unexplored in adequate clinical trials, which are worth being performed.