Co-administration Of Zinc Research Articles

Zinc protects against lead-induced testicular damage via modulation of steroidogenic and xanthine oxidase/uric acid/caspase 3-mediated apoptotic signaling in male Wistar rats

Aim This study evaluated the effect of lead, with or without zinc co-administration, on steroidogenic and xanthine oxidase (XO)/uric acid (UA)/caspase 3-mediated apoptotic signaling in the testis. Materials and methods Forty male Wistar rats were divided into four groups at random; vehicle-treated control, zinc-treated, lead-treated, and lead + zinc-treated groups. Results Lead exposure significantly lowered overall weight gain, testicular, epididymal, seminal vesicle, and prostate weights. Also, lead decreased sperm count, viability and motility but increased the fraction of sperm with aberrant morphology. In addition, lead caused a marked rise in the level of UA and XO activity but a decrease in nuclear factor erythroid 2-related factor 2 (Nrf2), reduced glutathione (GSH) as well as total antioxidant capacity (TAC) levels, and superoxide dismutase (SOD) and catalase activities. Furthermore, lead increased the testicular levels of nuclear factor kappa B (NFkB), interleukin-1beta (IL-1β), and tumour necrotic factor-alpha (TNF-α), which were associated with an increase in testicular caspase 3 activity and DNA fragmentation as well as a decline in circulating gonadotropin releasing hormone (GnRH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, and testicular 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17β-hydroxysteroid dehydrogenase (17β-HSD). These were associated with lead-induced degenerative changes in testicular tissues evidenced by shrunken seminiferous tubules, degeneration and sloughing of germ cells. Co-administration of zinc prevented lead-induced testicular injury by ameliorating oxidative stress, apoptosis, and inflammation through downregulation of XO/UA/caspase 3 pathway and upregulation of testicular 3β-HSD/17β-HSD. Conclusion This study demonstrated that zinc protected against lead-induced testicular toxicity via the downregulation of XO/UA/caspase 3 signaling.

Zinc improves sexual performance and erectile function by preventing penile oxidative injury and upregulating circulating testosterone in lead-exposed rats

ABSTRACTAim:The present study evaluated the effect of lead exposure with and without zinc therapy on male sexual and erectile function.Methods:Twenty male Wistar rats were randomly assigned into four groups; the control, zinc-treated, lead-exposed, lead + zinc-treated groups. Administrations were per os daily for 28 days.Results:Zinc co-administration significantly improved absolute and relative penile weights and the latencies and frequencies of mount, intromission, and ejaculation in lead-exposed rats. Also, zinc ameliorated lead-induced reductions in motivation to mate and penile reflex/erection. These findings were accompanied by attenuation of lead-induced suppression of circulating nitric oxide (NO), penile cyclic guanosine monophosphate (cGMP), dopamine, serum luteinizing hormone, follicle-stimulating hormone, and testosterone. In addition, zinc alleviated lead-induced upregulation of penile activities of acetylcholinesterase and xanthine oxidase (XO), and uric acid (UA) and malondialdehyde (MDA) levels. Furthermore, zinc ameliorated the lead-induced decline in penile nuclear factor erythroid 2-related factor 2 (Nrf2) and reduced glutathione (GSH) levels, and catalase, superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione-S-transferase (GST) activities.Conclusion:This study revealed that co-administration of zinc improves lead-induced sexual and erectile dysfunction by suppressing XO/UA-driven oxidative stress and upregulating testosterone via Nrf2-mediated signaling.

Zinc normalizes hepatic lipid handling via modulation of ADA/XO/UA pathway and caspase 3 signaling in highly active antiretroviral therapy-treated Wistar rats

BackgroundAlthough highly active antiretroviral therapy (HAART) is effective in the management of HIV, it has been reported to induce hepatic injury and non-alcoholic fatty liver (NAFLD). However, there is a lack of data on the roles of the adenosine deaminase (ADA)/xanthine oxidase (XO)/uric acid (UA) pathway and caspase 3 signaling in HAART-induced NAFLD. Also, whether or not zinc confers protection against HAART-induced NAFLD is not known. AimThis study evaluated the involvement of the ADA/XO/UA pathway and caspase 3 signaling in HAART-induced hepatic lipid accumulation. It also evaluated the possible protective effect of zinc in HAART-induced hepatic lipid accumulation and injury. MethodsThirty two male Wistar rats (n = 8/group) were assigned into four groups namely; vehicle-treated (p.o), zinc-treated (3 mg/kg/day of elemental zinc; p.o), HAART-treated (a cocktail of 52.9 mg/kg of Efavirenz, 26.48 mg/kg of Lamivudine, and 26.48 mg/kg of Tenofovir; p.o), and HAART + zinc-treated groups. The treatment lasted for 8 weeks. ResultsHAART administration led to increased body weight and hepatic weight, but unaltered hepatic organo-somatic index. HAART exposure also resulted in impaired glucose homeostasis, evidenced by increased fasting blood glucose, hyperinsulinemia, and insulin resistance (IR), increased plasma and hepatic cholesterol and triglycerides, and impaired hepatic function as depicted by elevated hepatic injury markers and reduced glycogen synthase activity and glycogen content. These findings were accompanied by increased plasma and hepatic ADA and XO activities, UA and malondialdehyde levels, inflammatory markers, and caspase 3 activities. However, HAART suppressed plasma and hepatic antioxidant defenses. Furthermore, HAART distorted hepatic histoarchitecture and reduced hepatic sinusoidal diameter. Co-administration of zinc with HAART normalized HAART-induced alterations. ConclusionsThese findings showed that downregulation of the ADA/XO/UA pathway and caspase 3 signalings may rescue the liver from HAART-induced lipid accumulation and injury.

Immunotoxic Effects of Cypermethrin in Male Wistar Rats: Attenuation by Co-Administration of Zinc and Alpha-Lipoic Acid

Aim The present study investigated the effects of cypermethrin exposure on humoral and cellular immune response in rat and its attenuation by zinc and alpha-lipoic acid. Methods Cypermethrin at the dose levels of 40 mg and 80 mg/kg body weight were orally administered and pre-treatment of zinc (227 mg/L in drinking water) and alpha-lipoic acid (35 mg/kg body wt.) were done. Total leukocyte and differential leukocyte counts (DLC), phagocytic index, serum nitric oxide (NO) activity, total immunoglobulin concentration, quantitative hemolysis, proliferation assay of blood mononuclear cells were estimated and histological examination of spleen was accomplished. Results Total white blood cell (WBC) count and percentage of lymphocyte, serum nitric oxide activity (p<0.001) and quantitative hemolysis were increased significantly increased whereas neutrophil %, total serum immunoglobulin, and blood mononuclear cell proliferation (p<0.001) and the phagocytic function of peritoneal macrophages were significantly reduced in cypermethrin treated rats compared to control group rats at a dose-dependent manner. Zinc and alpha-lipoic acid pre-treatment reversed the results. Conclusion From the findings it can be concluded that the co-administration of zinc and alpha-lipoic acid significantly attenuated the immunotoxic effects in cypermethrin exposed rat.

Co-administration of zinc for treating and preventing arsenism in common carp Cyprinus carpio: An alternative to avoid physiological and cellular damages

Arsenic (As) contamination in water bodies has adverse effects on aquatic organisms. Zinc (Zn), as an important enzyme cofactor and efficient reactive oxygen species scavenger, plays an indispensable role in cellular homeostasis and biological functions. However, there has been less investigation on AsZn interaction in common carp (Cyprinus carpio). We hypothesize that Zn is a candidate for the treatment and prevention of arsenism. In general, feed efficiency, growth performance and organ indices did not significantly differ between the As or/and Zn group and the control groups (p > 0.05). However, arsenite significantly altered the intestinal morphological features and suppressed intestinal tight junction proteins (claudins, occluding, and zonula occludens) as indicated by mRNA and protein levels. Moreover, oxidative stress (malondialdehyde and organic 8-hydroxy-2-deoxyguanosine), inflammatory (nuclear factor kappa-B and pro-inflammatory cytokines) and detoxification parameters (metallothionein) in intestine and liver increased following arsenite exposure (p < 0.05), concomitant with innate immunity suppression (C4 and IgM; p < 0.01). These anomalies led to abnormal lipid metabolism (SREBP-1c pathway; p < 0.01) and endoplasmic reticulum stress (PERK-eIF2α, IRE1α and ATF6; p < 0.01). Overall, As impaired general physiological and cellular functions, and compromised the immune system of carp. Zn2+ restored these alterations, as evidenced by the reduction in inflammation and endoplasmic reticulum stress via the activation of the antioxidant system. Thus, Zn supplementation can be used to treat and prevent arsenism; it is a useful alternative to prevent physiological and cellular damage in the inland culture of carp.

Protective Effects of Co-administration of Zinc and Selenium Against Streptozotocin-Induced Alzheimer's Disease: Behavioral, Mitochondrial Oxidative Stress, and GPR39 Expression Alterations in Rats.

Changes in the concentrations of trace metals such as zinc (Zn) and selenium (Se) can pathologically lead to neurodegenerative conditions such as the Alzheimer's disease (AD). Previous studies have shown that mitochondrial dysfunction plays an important role in the pathogenesis of AD. Several male Wistar rats were randomly divided into five groups: sham group, AD group that received 3mg/kg of streptozotocin (STZ) intracerebroventricularly, AD + Zn group that received 10mg/kg of Zn intraperitoneally (i.p.) for 1week, AD + Se group that received 0.1mg/kg of Se i.p. for 1week, and AD + Zn + Se group that received 10mg/kg of Zn i.p. plus 0.1mg/kg of Se i.p. for 1week. At end of the study, behavioral tests and mitochondrial oxidative stress and GPR39 gene expression evaluations were carried out. Co-administration of Zn and Se significantly decreased the potential collapse of mitochondrial membrane, reactive oxygen species levels, and lipid peroxidation levels while significantly increased cognitive performance, superoxide dismutase (SOD), glutathione peroxidase, and catalase activity in the brain mitochondria compared with the STZ group. In addition, no significant changes were observed in GPR39 expression in the co-treated group. Findings of the current study showed that ZnR/GPR39 receptor, mitochondrial dysfunction, and oxidative stress play important roles in the pathogenesis of AD. Co-treatment of Zn and Se improved the cognitive performance, mitochondrial dysfunction, and oxidative stress caused by STZ-induced AD. Therefore, therapeutic approaches to improve mitochondrial function could be effective in preventing the initiation and progression of AD.

Effect of co-administration of zinc and fluoxetine in the chronic restraint stress model of depression in mice

effect of co-administration of zinc and fluoxetine in the chronic restraint stress model of depression in mice

Ketamine-induced behavioural and brain oxidative changes in mice: an assessment of possible beneficial effects of zinc as mono- or adjunct therapy.

We studied the influence of zinc, haloperidol or olanzapine on neurobehaviour (open-field, radial arm maze and elevated plus maze) and brain antioxidant status in vehicle- or ketamine-treated mice, with the aim of ascertaining the potentials of zinc in counteracting ketamine's effects. Experiment 1 assessed the effects of zinc in healthy animals and the relative degrees of modulation of ketamine's effects by zinc, haloperidol or olanzapine, respectively. Experiment 2 assessed the modulation of ketamine's effects following co-administration of zinc with haloperidol or olanzapine. Male mice weighing 18-20g each were used. Animals were pretreated with ketamine (except vehicle, zinc, haloperidol and olanzapine controls) for 10days before commencement of 14-day treatment (day 11-24) with vehicle, zinc, haloperidol or olanzapine (alone or in combination). Ketamine injection also continued alongside zinc and/or standard drugs in the ketamine-treated groups. Zinc, haloperidol and olanzapine were administered by gavage. Treatments were given daily and behaviours assessed on days 11 and 24. On day 24, animals were sacrificed and whole brain homogenates used for estimation of glutathione, nitric oxide and malondialdehyde (MDA) levels. Ketamine increased open-field behaviours, nitric oxide and MDA levels, while it decreased working memory, social interaction and glutathione. Administration of zinc alone or in combination with haloperidol or olanzapine was associated with variable degrees of reversal of these effects. Zinc may have the potential of a possible therapeutic agent and/or adjunct in the reversal of schizophrenia-like changes in behaviour and brain oxidative status.

Administration of Zinc with Paroxetine Improved the Forced Swim Test Behavioral Pattern of Treated Mice in Acute and Sub-Acute Study

Despite progressive improvement in treating major depressive disorder (MDD), it remains mostly unresponsive to one antidepressant medication. Zinc is a brain highly abundant trace metal, a brain derived neurotrophic factor (BDNF) inducer, a modulator of synaptic plasticity and potent suppressor of the NMDA receptors. We proposed that co-administration of zinc with the antide-pressants may represent a valuable regimen to improve the efficacy of these drugs. This work has been implemented to evaluate the behavioral changes of acute and sub-acute co-administration of zinc with Paroxtine in mice. Methods: The animals were injected intra-peritoneal with either Paroxtine (20 mg/kg) which was a selective serotonin reuptake inhibitor (SSRI), zinc sulfate (30 mg/kg) or Paroxtine in combination with zinc for one day and one week (once daily). The pattern of the animal behavior was assessed in the forced swim test (FST). Results and Discussion: The behavioral patterns of the animals in the FST include immobility, swimming and climbing. Successful antidepressant should decrease the immobility time with either increase in swimming and/or climbing behavior based on the drug pharmacological activity. Our results revealed a significant decrease of immobility and increase of swimming behavior indicating serotonin-dependent pharmacological activity of Paroxtine or zinc alone as well as in the animals treated with zinc in combination with Paroxtine. There was no significant difference in the animals’ behavior between acute and sub-acute treatment with zinc or even upon its addition to paroxetine. Our data support the concept that co-administration of zinc may provide further antidepressant activity. Zinc may offer additional clinical value particularly in geriatric patients or other populations where zinc level has shown dramatic decrease.

Effects of supplement therapy on sperm parameters, protamine content and acrosomal integrity of varicocelectomized subjects.

Surgical repair of varicocele has long been a procedure to correct spermatogenesis. However, the outcome has been reported to be inadequate. We combined varicocelectomy with supplement therapy to evaluate the concurrent effect of these procedures. A prospective randomized controlled study was undertaken to investigate the effects of zinc sulfate, folic acid and zinc sulfate/folic acid on sperm quality, protamine content and acrosomal integrity following surgical repair of varicocele. Male subjects with palpable varicocele were included in the study and randomized into four groups. Subjects received Zinc sulfate, Folic acid, Zinc sulfate/Folic acid or placebo for 6 months. A semen sample was obtained before surgery and 3 and 6 months after surgical repair. Semen samples were evaluated for sperm parameters as well as chromatin content and acrosomal integrity. Most of the evaluated parameters showed a mild improvement after varicocelectomy in the placebo group. Interestingly, co-administration of Zinc sulfate and folic acid improved most factors significantly. Folic acid administration but not zinc sulfate could increase sperm number. Hence, Zinc sulfate was better than folic acid when change in morphology was assessed, and none of them was significantly effective in sperm motility. In Zinc sulfate and Folic acid groups, protamine content and halo formation rate significantly improved. We may conclude that co-administration of zinc and folic acid significantly improved sperm parameters and increased varicocelectomy outcomes. So, medical treatment with compatible drugs after surgery might be advantageous for obtaining acceptable results.

Therapeutic Influence of Zinc and Ascorbic Acid Against Lead induced Biochemical Alterations

The influence of co-administration of zinc (10mg/kg, intraperitoneal [ip]) and ascorbic acid (10, 20 and 30mg/kg, ip) against lead (lead acetate; 35mg/kg, ip for 3days) induced biochemical alterations was studied in young albino rats. The results revealed significant fall in hemoglobin content, on the other hand significant raise in the activity of serum transaminases and serum alkaline phosphatase after lead administration. Significant increase in lipid peroxidation and decreased level of reduced glutathione in liver showed oxidative stress due to lead exposure. Total protein content in liver and kidney were diminished after lead exposure. Activity of acid phosphatase in liver and kidney and alkaline phosphatase in kidney was increased significantly. Zinc and ascorbic acid treatment showed moderate therapeutic efficacy when administered individually, whereas more pronounced protective effects were observed after combined therapy of zinc and different doses of ascorbic acid. The results thus, suggested that co-administration of zinc and ascorbic acid may be useful in restoration of lead induced biochemical alterations.

Oxidative damage, biochemical and histopathological alterations in rats exposed to chlorpyrifos and the antioxidant role of zinc

The protective effects of zinc on liver and kidney injury induced by chlorpyrifos (CPF) were investigated in rats. Male and female rats were orally administered CPF at a dose of 6.75 mg kg −1 body weight for 28 consecutive days. An additional CPF group received zinc (227 mg l −1) in drinking water throughout the experimental duration. Two groups more served as controls. Administration of CPF resulted in a significant increase in serum lipid peroxidation (LPO) level, while induced significant decreases in the activities of plasma superoxide dismutase (SOD), glutathione-S-transferase (GST) and serum acetylcholinesterase (AChE) either in male or female rats. Similarly, a significant increase in the levels of various serum marker enzymes [e.g. aminotransferases (AST and ALT), lactate dehydrogenase (LDH) and gamma glutamyl transferase (GGT)] and increase the level of total protein, uric acid and creatinine. In contrast, co-administration of zinc to CPF-treated animals restored most of these biochemical parameters to within normal levels. In case of AChE, supplementation of zinc showed little alteration in the activity of this enzyme especially in male rats treated with CPF. CPF caused histopathological change in liver and kidneys of male and female rats. However, zinc administration to CPF-treated animals resulted in overall improvement in liver and kidneys damage, emphasizing its antioxidant role. In light of the available data, it can deduce that CPF-induced lipid peroxidation, oxidative stress, liver and kidneys damage in male and female rats, and conjunction supplementation of zinc has resulted in pronounced ameliorating effect.

Magnesium and other bivalent cations influence upon sodium montelukast effect in experimental-induced thermoalgesia

We tested the influence of magnesium, zinc and copper upon the montelukast (MK, antagonist of cysteinyl leukotriene receptor type 1) effect in experimentally-induced thermoalgesia. We worked on 5 groups of 10 adults, each Wistar rats, that received: group I-control; group II: MK (10 mg/kg) unique administration; group III: MgCl2 (1 mM/kg/day) i.p., 3 days and MK (10 mg/kg) unique administration on the 3rd day; group IV: ZnCl2, (0.1 mM/kg/day), i.p., 3 days and MK (10 mg/kg) unique administration on the 3rd day; group V: copper acetate (0.05 mM/kg/day), i.p., 3 days and MK (10 mg/kg) unique administration on the 3rd day. We determined the thermoalgesic sensitivity (TS) using a tail flick analgesia meter, initially, 3 days after daily cation administration and 3 hours after MK administration. Our data show that MK has a statistically significant reduction of TS vs control group (3.76 +/- 1.04 s vs 1.81 +/- 0.98 s, p < 0.05). Copper and magnesium administration do not significantly change the MK effect to decrease TS. The co-administration of zinc and MK statistically significantly increased the TS of the group that received only MK (2.51 +/- 0.21 s vs 3.76 +/- 1.04 s, p < 0.05). Animals that received only cations (in the above mentioned doses) did not significantly change TS.

Zinc mediates normalization of hepatic drug metabolizing enzymes in chlorpyrifos-induced toxicity

The present study investigated the protective effects of zinc in attenuating the altered activities of drug metabolizing enzymes in the livers of rats intoxicated with chlorpyrifos. Male Sprague–Dawley rats received oral chlorpyrifos treatment (at a dose level of 13.5 mg/kg body weight in corn oil every alternate day), zinc supplementation alone (at a dose level of 227 mg/l in drinking water), or combined chlorpyrifos plus zinc treatments for a total duration of 8 weeks. The effects of different treatments were studied on the specific activities of various drug metabolizing enzymes including cytochrome P 450, cytochrome b 5, NADPH cytochrome- c-reductase, NADH cytochrome- c-reductase, aminopyrene- N-demethylase (APD) and aromatic hydrocarbon hydroxylase (AHH). Additionally, serum zinc levels were also determined in each of the treatment groups at the end of the study. Chlorpyrifos treatment resulted in a significant decrease in the serum zinc concentrations. Analogous to these changes, we observed significant depression in the activities of majority of the drug metabolizing enzymes investigated in the present study, except for AHH, where the decrease in enzyme activity was not statistically significant. However, zinc treatment to chlorpyrifos treated animals effectively restored the depressed serum zinc levels to within normal limits. Similarly, co-administration of zinc to chlorpyrifos intoxicated animals normalized the enzymatic activities of cytochrome P 450, NADPH cytochrome- c-reductase and NADH cytochrome- c-reductase within normal range. Collectively, these findings suggest that zinc plays an important role in regulating the hepatic activities of drug metabolizing enzymes in chlorpyrifos intoxicated animals, although it remains to be determined whether such protective effects of zinc are regulated directly, or through some indirect mechanism.

Co-administration of zinc and n-acetylcysteine prevents arsenic-induced tissue oxidative stress in male rats

Arsenic is a widespread environmental toxicant that may cause neuropathy, skin lesions, vascular lesions and cancer upon prolonged exposure. Improving nourishment like supplementation of micronutrients, antioxidants, vitamins and amino acids could be able to halve the risk in those who were previously the poor nourished. The present study was planned to investigate the preventive effects of zinc and n-acetylcysteine (NAC) supplementation either alone or in combination with arsenic on selected biochemical variables indicative of oxidative stress and liver injury in male rats. For 3 weeks 25 male wistar rats were exposed to arsenic as sodium arsenite (2 mg/kg, orally through gastric intubation) either alone or in combination with NAC (10 mg/kg, intraperitoneally), zinc (5 mg/kg, orally) or zinc plus NAC. Animals were sacrificed 24 h after the last dosing for various biochemical parameters. Concomitant administration of zinc with arsenic showed remarkable protection against blood δ-aminolevulinic acid dehydratase (ALAD) activity as well as providing protection to hepatic biochemical variables indicative of oxidative stress (like thiobarbituric acid reactive substances (TBARS) level, catalase) and tissue injury. NAC supplementation on the other hand, was moderately effective in protecting animals from the toxic effects of arsenic. Interestingly, concomitant administration of zinc and NAC was most effective compared to zinc or NAC in eliciting above-mentioned protective effects. The above results suggest significant protective value of combined zinc and NAC administration in acute arsenic exposure.

Chlorpyrifos-induced alterations in the activities of carbohydrate metabolizing enzymes in rat liver: The role of zinc

The present study was conducted to evaluate the adverse effects of chlorpyrifos on the key enzymes of carbohydrate metabolism in liver, and also to assess the role of zinc under these toxic conditions. Male Sprague–Dawley (SD) rats received either oral chlorpyrifos treatment (13.5 mg/kg body weight in corn oil) every alternate day, zinc alone (227 mg/l in drinking water), or combined chlorpyrifos and zinc treatments for a total duration of 8 weeks. The effects of different treatment regimens were studied on various enzymes of carbohydrate metabolism in the rat livers, which included hexokinase, glucose-6-phosphatase, fructose-1,6-diphosphatase, glycogen phosphorylase, succinate dehydrogenase (SDH), lactate dehydrogenase (LDH) and the levels of glycogen. In vitro uptake of 14C- d-glucose was also assessed in liver slices after similar treatments. Chlorpyrifos intoxication resulted in a significant increase in the activities of glucose-6-phosphatase and glycogen phosphorylase, whereas, it caused a significant inhibition in the levels of hexokinase, SDH, LDH and glycogen content. However, zinc treatment to chlorpyrifos-intoxicated animals was able to normalize the activities of most of these enzymes to either close to, or within normal limits. Chlorpyrifos intoxication demonstrated significantly inhibited 14C- d-glucose uptake in liver slices, which again was reversed to normal limits following simultaneous zinc treatment. Levels of metallothionein were also found to be depressed in chlorpyrifos-treated animals, but tended to increase significantly on co-administration of zinc to chlorpyrifos-treated group. Hence, the present study clearly suggests that zinc plays an important role in regulating the hepatic activities of the enzymes involved in carbohydrate metabolism under conditions of chlorpyrifos toxicity.

Protective effects of zinc on lipid peroxidation, antioxidant enzymes and hepatic histoarchitecture in chlorpyrifos-induced toxicity

The present study investigated the hepatoprotective role of zinc in attenuating the toxicity induced by chlorpyrifos in rat liver. Male Sprague–Dawley (SD) rats received either oral chlorpyrifos (13.5 mg/kg body weight), zinc alone (227 mg/l in drinking water) or combined chlorpyrifos plus zinc treatment for a total duration of 8 weeks. The effects of these treatments were studied on various parameters in rat liver, including lipid peroxidation, antioxidant enzymes, levels of metallothionein (MT) and hepatic histoarchitecture. Chlorpyrifos treatment resulted in a significant increase in hepatic lipid peroxidation and activities of superoxide dismutase (SOD), glutathione peroxidase (G-Px) and glutathione reductase (GR). On the contrary, chlorpyrifos intoxication caused a significant inhibition in the levels of reduced glutathione (GSH), catalase (CAT) and glutathione- S-transferase (GST) activities. However, zinc treatment to chlorpyrifos-intoxicated animals normalized the otherwise raised levels of lipid peroxidation to within normal limits. Moreover, zinc treatment to these animals resulted in an elevation in the levels of GSH, catalase and GST, as well as a significant decrease in the levels of SOD. Levels of MT were also found to be depressed in chlorpyrifos-treated animals, but tended to increase following co-administration of zinc. Additionally, chlorpyrifos-treated animals demonstrated increased vacuolization, necrosis and ballooning of the hepatocytes and dilatation of sinusoids as well as increase in the number of binucleated cells. However, zinc administration to chlorpyrifos-treated animals resulted in overall improvement in the hepatic histoarchitecture, emphasizing the protective potential of zinc. Hence, the present study suggests the protective potential of zinc in alleviating the hepatic toxicity induced by chlorpyrifos.

Arsenic antagonism studies with monoisoamyl DMSA and zinc in male mice

Administration of zinc either alone or in combination with monoisoamyl dimercaptosuccinic acid (DMSA) during and post-arsenic exposure was investigated in male mice. The animals were administered 2 mg kg −1 arsenic as sodium arsenite, intraperitoneally, once daily for 5 days either alone or in combination with 10 mg kg −1, zinc (as zinc acetate, orally), 50 mg kg −1 monoisoamyl dimercaptosuccinic acid (MiADMSA) given orally (p.o.), 2 h after arsenic administration. Another group of arsenic treated animals was given both zinc (10 mg kg −1) and MiADMSA (50 mg kg −1, p.o.). Animals were sacrificed 24 h after the last dose. In another set of experimentation, arsenic pre-exposed mice (2 mg kg −1, i.p. for 5 days) were treated with saline, zinc, MiADMSA or zinc plus MiADMSA for next 3 days and sacrificed thereafter. Exposure to arsenic led to a significant inhibition of blood δ-aminolevulinic acid dehydratase (ALAD), depletion of glutathione (GSH) level and marginal elevations of zinc protoporphyrin (ZPP). Arsenic exposure caused a significant decrease in hepatic and renal GSH level and an increase in liver oxidized glutathione (GSSG) and liver and kidney thiobarbituric acid reactive substance (TBARS) levels. Concomitant administration of zinc with arsenic provided significant protection to blood ALAD activity while, GSH and ZPP levels remained unaltered. Co-administration of MiADMSA with arsenic significantly prevented accumulation of arsenic in blood, liver and kidney while, zinc had no effect on tissue arsenic concentration. Combined administration of zinc and MiADMSA had no major additional beneficial effects over their individual effects. Interestingly, post-arsenic exposure treatment with MiADMSA provided significant recovery in blood ALAD activity while, zinc supplementation alone had no effect. The best results however, were obtained when MiADMSA was administered along-with zinc. Most of the biochemical variables indicative of hepatic oxidative stress responded favorably to MiADMSA treatment while, zinc administration had no effect. Administration of MiADMSA significantly depleted arsenic concentration from the soft tissues while, combined zinc and MiADMSA had no additional beneficial effect over the individual effect of MiADMSA. The results thus lead us to conclude that in order to achieve best effects of chelation therapy, co-administration of zinc with chelator might be preferred. However, detailed experimental studies with variable doses and after chronic arsenic exposure are required.

Protective effects of zinc in chlorpyrifos induced hepatotoxicity: a biochemical and trace elemental study.

The toxicological literature is replete with studies attempting to explain the mechanism of action of organophosphorus (OP) insecticides to their anticholinesterase activities, but not much is known about the metabolism and detoxification of these compounds. The goal of this study was to ascertain the toxic effects of chlorpyrifos, one of the most widely used OPs, on the liver of male rats and also to evaluate the protective potential of zinc in mediating its toxic effects. It was observed that chlorpyrifos (13.5 mg/kg body weight) treatment resulted in significant inhibition (p < 0.001) of serum and hepatic acetylcholinesterase (AChE) activities after 8 wk. However, zinc-treated (227 mg/L drinking water) animals resulted in significant normalization of the inhibited AChE activities. Similarly, a significant increase in the levels of various serum and liver marker enzymes (viz. alkaline phosphatase, aspartate aminotransferase [AST], and alanine aminotransferase [ALT]) was observed following treatment with chlorpyrifos. However, coadministration of zinc to these animals restored these enzymes to within normal limits, even though some increase in the activity of serum ALT and hepatic alkaline phosphatase still persisted at the end of the study. Chlorpyrifos treatment diminished serum and hepatic zinc levels significantly (p < 0.01 to p < 0.001) compared to normal control animals. Serum iron concentrations also plummeted significantly following chlorpyrifos treatment. On the contrary, serum copper levels were significantly increased (p < 0.01) in chlorpyrifos-treated animals, but they were normalized following zinc supplementation to the rats in this group. Interestingly, chlorpyrifos treatment resulted in elevated hepatic levels of copper, iron, and selenium, but zinc treatment could only partially restore the raised elemental concentrations. These data clearly demonstrate the potential role of zinc in mediating the toxic effects of chlorpyrifos, presumably because of their antioxidant properties and also their possible interaction with other trace elements in maintaining the cellular harmony.

The effect of zinc supplementation on the effects of lead on the rat testis

With increasing concerns about environmental pollution, the interaction of micronutrients with toxic metals is of great interest. The present study was designed to investigate testicular effects of lead following concomitant administration of zinc. Lead was administered orally as lead acetate (50 mg/kg b.w.) daily for 3 months to male Portan rats with or without zinc (1 mg/kg b.w. as zinc sulphate). The control group was given the same volume of distilled water. Endpoints included lead concentration in various body organs as well as in the reproductive system, including testicular subfractions; the testicular enzymes superoxide dismutase (SOD) and catalase; the marker enzyme δ-aminolevulinic acid dehydratase (δ-ALAD); and testicular histoarchitecture. The concentrations of lead in bone, kidney, prostate, testis, liver, epididymis, spleen, seminal vesicles, and blood were significantly higher in lead-treated rats. Lead deposition was reduced in animals that received supplemental zinc. There was a 30% reduction in lead deposition in the testis when zinc was coadministered. At the subcellular level, there was differential accumulation of lead; the nucleus preferentially took up the metal after lead treatment alone, while zinc coadministration shifted lead accumulation to the mitochondria. A significant decrease in δ-ALAD and in SOD activity was seen in the testis with lead treatment. Coadministration of zinc prevented these decreases, at least partially. Zinc coadministration did not prevent the inhibition of catalase observed with lead treatment. Histologically, the alterations in the testis with lead treatment alone were more pronounced compared to animals in which zinc was supplemented. Improvement in the inhibition of δ-ALAD and in the ubiquitous cellular enzyme SOD suggests less testicular tissue damage due to detoxification of free radicals. In conclusion, zinc supplementation ameliorates lead-induced testicular damage both at the cellular and subcellular level. The protective effect may be due to differential distribution of lead, either because of competition between lead and zinc or displacement of lead by zinc.