Protective effect of manganese in cadmium-induced hepatic oxidative damage, changes in cadmium distribution and trace elements level in mice

Assessment of the Impact of Trace Essential Metals on Cancer Development

This study examines the impact of zinc, copper, cobalt, iron, and manganese on cancer development, considering their dual roles as potential promoters or inhibitors within tumorigenesis. A comprehensive analysis of existing literature and experimental data is conducted to elucidate the intricate relationship between these trace elements and cancer progression. The findings highlight the multifaceted effects of zinc, copper, cobalt, iron, and manganese on various aspects of cancer development, including cell proliferation, angiogenesis, and metastasis. Understanding the nuanced interactions between these trace elements and cancer could offer crucial insights into tumorigenesis mechanisms and facilitate the identification of novel biomarkers and therapeutic targets for cancer prevention and treatment strategies. This research underscores the importance of considering the roles of essential trace elements in cancer biology and may ultimately contribute to advancements in precision medicine approaches for combating cancer.

The Body Status of Manganese and Activity of This Element-Dependent Mitochondrial Superoxide Dismutase in a Rat Model of Human Exposure to Cadmium and Co-Administration of Aronia melanocarpa L. Extract

The impact of a polyphenol-rich 0.1% aqueous extract from Aronia melanocarpa L. berries (AE) on the body status of manganese (Mn) and the activity of this essential element-dependent mitochondrial superoxide dismutase (MnSOD) during treatment with cadmium (Cd) was investigated in a rat model of low-level and moderate environmental human exposure to this xenobiotic (1 and 5 mg Cd/kg diet, respectively, for 3-24 months). The exposure to Cd, dose- and duration-dependently, affected the body status of Mn (apparent absorption, body retention, serum and tissue concentrations, content in some organs and total Mn body burden, and urinary and faecal excretion) and the activity of MnSOD in the mitochondria of the liver, kidney, and brain. The administration of AE during the exposure to Cd prevented or at least partially protected the animals from the perturbation of the metabolism of Mn, as well as ameliorated changes in the activity of MnSOD and the concentration of Mn and protected from Cd accumulation in the mitochondria. In conclusion, AE may protect from disorders in the body status of Mn and influence the antioxidative capacity of cells under chronic exposure to Cd. The findings confirm the protective impact of aronia berries products against Cd toxicity.

Curative Potential of Substances with Bioactive Properties to Alleviate Cd Toxicity: A Review

Rapid urbanization and industrialization have led to alarming cadmium (Cd) pollution. Cd is a toxic heavy metal without any known physiological function in the organism, leading to severe health threat to the population. Cd has a long half-life (10-30 years) and thus it represents serious concern as it to a great extent accumulates in organs or organelles where it often causes irreversible damage. Moreover, Cd contamination might further lead to certain carcinogenic and non-carcinogenic health risks. Therefore, its negative effect on population health has to be minimalized. As Cd is able to enter the body through the air, water, soil, and food chain one possible way to defend and eliminate Cd toxicities is via dietary supplements that aim to eliminate the adverse effects of Cd to the organism. Naturally occurring bioactive compounds in food or medicinal plants with beneficial, mostly antioxidant, anti-inflammatory, anti-aging, or anti-tumorigenesis impact on the organism, have been described to mitigate the negative effect of various contaminants and pollutants, including Cd. This study summarizes the curative effect of recently studied bioactive substances and mineral elements capable to alleviate the negative impact of Cd on various model systems, supposing that not only the Cd-derived health threat can be reduced, but also prevention and control of Cd toxicity and elimination of Cd contamination can be achieved in the future.

Cytosolic and Metallothionein-Bound Hepatic Metals and Detoxification in a Sentinel Teleost, Dules auriga, from Southern Rio de Janeiro, Brazil

Dules auriga, a native Brazilian teleost, was applied as a sentinel species regarding metal contamination at Ilha Grande Bay, previously considered a reference site in Southeastern Brazil. Cytosolic (S50) and metallothionein-bound (HTS50) hepatic iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), cadmium (Cd), and silver (Ag) were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), while metallothionein (MT) concentrations were determined by polarography. Ag concentrations in both cytosolic fractions were below the limit of detection. All other HTS50 metal contents were significantly lower than S50 contents. No significant associations were found for MT. Fe and Mn S50 were positively and moderately correlated to total length, as well as HTS50 Mn, while total weight was correlated to both Mn fractions, suggesting that environmental Mn and Fe concentrations may influence fish growth. A moderate correlation between the condition factor and the S50 Cu fraction was observed, also indicating that Cu may affect fish growth. Inter-element correlations were observed, including between Cd, a toxic element, and Mn and Zn, both essential elements. Calculated molar ratios indicate that both Mn and Zn are in molar excesses compared with Cd, corroborating literature assessments regarding protective Mn and Zn effects against Cd. Lack of MT correlations suggests that metal concentrations may not be high enough to reach an MT induction threshold and that MT variability is probably linked to environmental metal concentrations. Therefore, the increased environmental contaminant levels observed in the study area indicate the need for biomonitoring efforts aiming at the application of efficient mitigation measures.

Effect of Manganese Chloride and of Cotreatment with Cadmium Chloride on the In Vitro Proliferative, Motile and Invasive Behavior of MDA-MB231 Breast Cancer Cells

We examined the dose⁻response effect of MnCl₂ on the proliferative behavior of triple-negative breast cancer MDA-M231 cells vs. immortalized HB2 cells from breast epithelium taken as nontumoral counterparts. We also tested the effect of MnCl₂ on tumor cell invasiveness in vitro by evaluating the relative invasion indexes through Boyden chamber assays. Moreover, we checked whether cotreatment with both MnCl₂ and CdCl₂ could modify the observed biological response by MDA-MB231 cells. Our results show a promotional impact of MnCl₂ on cell proliferation, with 5 µM concentration inducing the more pronounced increase after 96-h exposure, which is not shared by HB2 cells. Exposure to 5 µM MnCl₂ induced also an elevation of the relative invasion index of cancer cells. The Mn-mediated stimulatory effects were counteracted by cotreatment with CdCl₂. These data support the concept that human exposure to high environmental concentrations of Mn may increase the risk of carcinogenesis and metastasis by prompting the expansion and dissemination of triple-negative breast cancer cells. On the other hand, the Mn-counteracting anticancer property of Cd looks promising and deserves a more detailed characterization of the involved intracellular targets aimed to the molecular modeling of specific antineoplastic agents against malignant breast cancer spreading.

Hematobiochemical Disturbances and Oxidative Stress After Subacute Manganese Chloride Exposure and Potential Protective Effects of Ebselen in Rats

The present study aimed to detect the possible disturbances induced by subacute exposure to manganese chloride (MnCl₂) on some biomarkers of hematology, clinical chemistry and oxidative stress, serum iron homeostasis, and ferritin status beside the histopathological alterations in hepatic and renal tissues, and the potential protective effects of ebselen on the Mn toxicity were also evaluated. Forty-eight rats were divided into four groups: Group 1 was used as a control. Groups 2, 3, and 4 were administered of ebselen as a single protective dose (15 mg/kg BW) intraperitoneal, daily manganese chloride (50 mg/kg BW) orally, and ebselen plus manganese chloride, respectively. The administrations were conducted for 30 days. Blood and tissue samples were collected at the end of the treatment for various experimental tests. Results revealed that MnCl₂ did not significantly change in erythrogram with leukocytosis and neutrophilia but significantly increased serum aminotransferases and alkaline phosphatase activities, bilirubin (total, direct, and indirect), globulins, triglycerides, total cholesterol, creatinine, urea, manganese, iron and ferritin concentrations and hepatic glutathione, renal malondialdehyde and nitric oxide levels and hepatic superoxide dismutase activity, while serum albumin, hepatic malondialdehyde, and nitric oxide concentrations were significantly decreased besides non-statistical change in serum total proteins concentration. Ebselen has reduced the disturbances in these analytes in combined treatment group. Collectively, subacute exposure to MnCl₂ causes disturbance in the leukogram, and hepatic and renal functions with marked renal oxidative stress. It also disturbed serum iron homeostasis and ferritin status. Remarkably, ebselen appears to be highly effective in attenuating the various adverse effects of manganese.

Short-term effects of very low dose cadmium feeding on copper, manganese and iron homeostasis: A gastropod perspective

The available information on the interplay between low-dose cadmium intake and copper, manganese, and iron homeostasis in invertebrates is limited. We have currently studied the accumulation of these trace metals in the hepatopancreas of adult snails, Cantareus aspersus, following 14 and 28 days of exposure to low doses of dietary cadmium, up to 1 mg/kg dw (dry weight). The cadmium dose, but not the duration of exposure, had a significant effect on hepatopancreas copper deposition, the values being significantly elevated compared to controls. A significant peak in manganese levels at 14 days was found in snails administered the lowest cadmium dose. These increases occurred even in the absence of cadmium increase in the hepatopancreas. Our data suggest that low dose cadmium feeding can produce a transient disturbance in hepatopancreas copper and manganese homeostasis. Such responses may serve as early biomarkers of physiological changes occurring during the initial stages of cadmium intoxication.

Review of polyphenol-rich products as potential protective and therapeutic factors against cadmium hepatotoxicity

Recently, the growing attention of the scientific community has been focused on the threat to health created by environmental pollutants, including toxic metals such as cadmium (Cd), and on the need of finding effective ways to prevent and treat the unfavorable health effects of exposure to them. Particularly promising for Cd, and thus arousing the greatest interest, is the possibility of using various ingredients present in plants, including mainly polyphenolic compounds. As the liver is one of the target organs for this toxic metal and disturbances in the proper functioning of this organ have serious consequences for health, the aim of the present review was to discuss the possibility of using polyphenol-rich food products (e.g., chokeberry, black and green tea, blueberry, olive oil, rosemary and ginger) as the strategy in protection from this xenobiotic hepatotoxicity and treatment of this heavy metal-induced liver damage. Owing to the ability of polyphenols to bind ions of Cd and the strong antioxidative potential of these compounds, as well as their abundance in dietary products, it seems to be of high importance to consider the possibility of using polyphenols as potential preventive and therapeutic agents against Cd hepatotoxicity, determined by its strong pro-oxidative properties. Although most of the data on the effectiveness of polyphenols comes from studies in animals, the fact that some of them are derived from experimental models that reflect human exposure to this metal allows us to assume that some polyphenol-rich food products may be promising protective agents against Cd hepatotoxicity in humans.

Environmental exposure to cadmium-a risk for health of the general population in industrialized countries and preventive strategies

Cadmium (Cd) is a heavy metal belonging to the group of the main chemical pollutants of the natural and occupational environment in economically developed countries. The forecasts indicate that contamination of the environment with this toxic metal, and thus the exposure of the general population, will increase. Food (particularly plant products) is the main source of the general population exposure to this element. Moreover, an important, and often the main, source of intoxication with Cd is habitual tobacco smoking. Recent epidemiological studies have provided numerous evidence that even low-level environmental exposure to this toxic metal, nowadays occurring in numerous economically developed countries, creates a risk for health of the general population. The low-level lifetime exposure to this metal may lead to the damage to the kidneys, liver, skeletal system, and cardiovascular system, as well as to the deterioration of the sight and hearing. Moreover, it has been suggested that environmental exposure to this xenobiotic may contribute to the development of cancer of the lung, breast, prostate, pancreas, urinary bladder, and nasopharynx. Taking the above into account, the aim of this review article is to draw more attention to Cd as an environmental risk factor for the health of the general population and the need to undertake preventive actions allowing to reduce the risk of health damage due to a lifetime exposure to this toxic metal.

Manganese promotes intracellular accumulation of AQP2 via modulating F-actin polymerization and reduces urinary concentration in mice

Aquaporin-2 (AQP2) is a water channel protein expressed in principal cells (PCs) of the kidney collecting ducts (CDs) and plays a critical role in mediating water reabsorption and urine concentration. AQP2 undergoes both regulated trafficking mediated by vasopressin (VP) and constitutive recycling, which is independent of VP. For both pathways, actin cytoskeletal dynamics is a key determinant of AQP2 trafficking. We report here that manganese chloride (MnCl₂) is a novel and potent regulator of AQP2 trafficking in cultured cells and in the kidney. MnCl₂ treatment promoted internalization and intracellular accumulation of AQP2. The effect of MnCl₂ on the intracellular accumulation of AQP2 was associated with activation of RhoA and actin polymerization without modification of AQP2 phosphorylation. Although the level of total and phosphorylated AQP2 did not change, MnCl₂ treatment impeded VP-induced phosphorylation of AQP2 at its serine-256, -264, and -269 residues and dephosphorylation at serine 261. In addition, MnCl₂ significantly promoted F-actin polymerization along with downregulation of RhoA activity and prevented VP-induced membrane accumulation of AQP2. Finally, MnCl₂ treatment in mice resulted in significant polyuria and reduced urinary concentration, likely due to intracellular relocation of AQP2 in the PCs of kidney CDs. More importantly, the reduced urinary concentration caused by MnCl₂ treatment in animals was not corrected by VP. In summary, our study identified a novel effect of MnCl₂ on AQP2 trafficking through modifying RhoA activity and actin polymerization and uncovered its potent impact on water diuresis in vivo.

Redox dynamics of manganese as a mitochondrial life-death switch

Sten Orrenius, M.D., Ph.D., pioneered many areas of cellular and molecular toxicology and made seminal contributions to our knowledge of oxidative stress and glutathione (GSH) metabolism, organellar functions and Ca+2-dependent mechanisms of cell death, and mechanisms of apoptosis. On the occasion of his 80th birthday, we summarize current knowledge on redox biology of manganese (Mn) and its role in mechanisms of cell death. Mn is found in all organisms and has critical roles in cell survival and death mechanisms by regulating Mn-containing enzymes such as manganese superoxide dismutase (SOD2) or affecting expression and activity of caspases. Occupational exposures to Mn cause "manganism", a Parkinson's disease-like condition of neurotoxicity, and experimental studies show that Mn exposure leads to accumulation of Mn in the brain, especially in mitochondria, and neuronal cell death occurs with features of an apoptotic mechanism. Interesting questions are why a ubiquitous metal that is essential for mitochondrial function would accumulate to excessive levels, cause increased H2O2 production and lead to cell death. Is this due to the interactions of Mn with other essential metals, such as iron, or with toxic metals, such as cadmium? Why is the Mn loading in the human brain so variable, and why is there such a narrow window between dietary adequacy and toxicity? Are non-neuronal tissues similarly vulnerable to insufficiency and excess, yet not characterized? We conclude that Mn is an important component of the redox interface between an organism and its environment and warrants detailed studies to understand the role of Mn as a mitochondrial life-death switch.

Eliminating Nox2 reactive oxygen species production protects dystrophic skeletal muscle from pathological calcium influx assessed in vivo by manganese-enhanced magnetic resonance imaging

KEY POINTS

Inhibiting Nox2 reactive oxygen species (ROS) production reduced in vivo calcium influx in dystrophic muscle. The lack of Nox2 ROS production protected against decreased in vivo muscle function in dystrophic mice. Manganese-enhanced magnetic resonance imaging (MEMRI) was able to detect alterations in basal calcium levels in skeletal muscle and differentiate disease status. Administration of Mn2+ did not affect muscle function or the health of the animal, and Mn2+ was cleared from skeletal muscle rapidly. We conclude that MEMRI may be a viable, non-invasive technique to monitor molecular alterations in disease progression and evaluate the effectiveness of potential therapies for Duchenne muscular dystrophy.

ABSTRACT

Duchenne muscular dystrophy (DMD) is an X-linked progressive degenerative disease resulting from a mutation in the gene that encodes dystrophin, leading to decreased muscle mechanical stability and force production. Increased Nox2 reactive oxygen species (ROS) production and sarcolemmal Ca2+ influx are early indicators of disease pathology, and eliminating Nox2 ROS production reduces aberrant Ca2+ influx in young mdx mice, a model of DMD. Various imaging modalities have been used to study dystrophic muscle in vivo; however, they are based upon alterations in muscle morphology or inflammation. Manganese has been used for indirect monitoring of calcium influx across the sarcolemma and may allow detection of molecular alterations in disease progression in vivo using manganese-enhanced magnetic resonance imaging (MEMRI). Therefore, we hypothesized that eliminating Nox2 ROS production would decrease calcium influx in adult mdx mice and that MEMRI would be able to monitor and differentiate disease status in dystrophic muscle. Both in vitro and in vivo data demonstrate that eliminating Nox2 ROS protected against aberrant Ca2+ influx and improved muscle function in dystrophic muscle. MEMRI was able to differentiate between different pathological states in vivo, with no long-term effects on animal health or muscle function. We conclude that MEMRI is a viable, non-invasive technique to differentiate disease status and might provide a means to monitor and evaluate the effectiveness of potential therapies in dystrophic muscle.

Cadmium Protection Strategies--A Hidden Trade-Off?

Cadmium (Cd) is a non-essential transition metal which is introduced into the biosphere by various anthropogenic activities. Environmental pollution with Cd poses a major health risk and Cd toxicity has been extensively researched over the past decades. This review aims at changing the perspective by discussing protection mechanisms available to counteract a Cd insult. Antioxidants, induction of antioxidant enzymes, and complexation of Cd to glutathione (GSH) and metallothionein (MT) are the most potent protective measures to cope with Cd-induced oxidative stress. Furthermore, protection mechanisms include prevention of endoplasmic reticulum (ER) stress, mitophagy and metabolic stress, as well as expression of chaperones. Pre-exposure to Cd itself, or co-exposure to other metals or trace elements can improve viability under Cd exposure and cells have means to reduce Cd uptake and improve Cd removal. Finally, environmental factors have negative or positive effects on Cd toxicity. Most protection mechanisms aim at preventing cellular damage. However, this might not be possible without trade-offs like an increased risk of carcinogenesis.

Tsga10 expression correlates with sperm profiles in the adult formalin-exposed mice

Testis-specific gene antigen10 (Tsga10), as a cytoskeletal protein in the sperm tail, impacts the sperm motility. This study investigates the correlation between sperm profile alterations and Tsga10 gene expression in adult mice exposed to formaldehyde (FA) and then treated with antioxidant effect of manganese (Mn²⁺ ). In this regard, we examined 35 NMRI adult male mice (6-8 weeks age) in 4 groups of control, sham, FA-exposed and FA+Mn²⁺ . The mice in FA+Mn²⁺ group were exposed to FA (10 mg kg^-1 twice a day) for 2 weeks and treated with daily Mn²⁺ administration (5 mg kg^-1 ) in the second week prior to sacrificing the mice for testis dissection. The right testis was dissected in each group and subjected to RNA extraction and cDNA syntheses for gene expression analysis by real-time PCR. The findings revealed that FA decreased sperm parameters and Tsga10 expression (52.6 ± 24.37%). However, the injected powerful manganese antioxidant improved sperm profile through overexpression of Tsga10 (121.6 ± 27.13%) under FA-induced stressful condition which proves the correlation between sperm profile and Tsga10 expression (P ≤ 0.05). This study also shows that Tsga10 expression protects sperm dysfunction in FA+Mn²⁺ group and resulting in better preservation of spermatozoa and improvement of male fertility.

Effects of Common Fig (Ficus carica) Leaf Extracts on Sperm Parameters and Testis of Mice Intoxicated with Formaldehyde

Formaldehyde (FA) is the leading cause of cellular injury and oxidative damage in testis that is one of the main infertility causes. There has been an increasing evidence of herbal remedies use in male infertility treatment. This assay examines the role of Ficus carica (Fc) leaf extracts in sperm parameters and testis of mice intoxicated with FA. Twenty-five adult male mice were randomly divided into control; sham; FA-treated (10 mg/kg twice per day); Fc-treated (200 mg/kg); and FA + Fc-treated groups. Cauda epididymal spermatozoa were analyzed for viability, count, and motility. Testes were weighed and gonadosomatic index (GSI) was calculated. Also, histoarchitecture of seminiferous tubules was assessed in the Haematoxylin and Eosin stained paraffin sections. The findings showed that FA significantly decreased GSI and increased percentage of immotile sperm compared with control group. Disorganized and vacuolated seminiferous epithelium, spermatogenic arrest, and lumen filled with immature germ cells were also observed in the testes. However, Fc leaf extracts improved sperm count, nonprogressive motility of spermatozoa, and GSI in FA-treated testes. Moreover, seminiferous tubule with spermatogenic arrest was rarely seen, indicating that Fc has the positive effects on testis and epididymal sperm parameters exposed with FA.

Selenium and rutin alone or in combination do not have stronger protective effects than their separate effects against cadmium-induced renal damage

CONTEXT

Selenium (Se) and rutin (RUT) are antioxidants that protect against tissue damage.

OBJECTIVE

In this study, the separate and combine protective effects of RUT and Se against cadmium (Cd)-induced renal damage were evaluated in rats.

MATERIALS AND METHODS

Wistar rats were treated by gavage to RUT (30 mg/kg) or Se (0.15 ppm) or Cd (200 ppm) in drinking water alone or in combination (30 mg/kg RUT +0.15 ppm Se + 200 ppm Cd). Corn oil was used as vehicle (2 mL/kg). After a 5-week treatment period, rat kidneys were removed for biochemical assays and histopathological examination. Se and Cd levels were evaluated by flame atomic absorption spectrophotometry.

RESULTS

The malondialdehyde and glutathione levels as well as superoxide dismutase and catalase activities in the Cd-treated animals were increased compared with control values (0.056 ± 0.0003 versus 0.011 ± 0.0005 μmol/mg; 0.005 ± 0.0006 versus 0.00085 ± 0.0002 μg/mg; 1.62 ± 0.09 versus 0.48 ± 0.12 units/mg; 650 ± 25 versus 361.89 ± 31 μmol H2O2/mg, respectively). Cd treatment was also associated with decreased renal Se concentration (4.19 ± 0.92 versus 7.73 ± 0.7 μg/g dry weight), increased alkaline phosphatase (0.07 ± 0.0015 versus 0.033 ± 0.0019 unit/mg), acid phosphatase (0.029 ± 0.0021 versus 0.015 ± 0.0016 unit/mg), and lactate dehydrogenase (0.032 ± 0.004 versus 0.014 ± 0.0027 unit/mg) activities, respectively, and with evidence of severe renal damage. The combination of RUT and Se or their separate effects prevented the Cd-induced oxidative renal damage. However, their combine effects do not have stronger effects than their separate effect against Cd-induced renal damage.

DISCUSSION AND CONCLUSION

RUT and Se function as potent antioxidant in the protection of renal damage induced by Cd.

Manganese pre-treatment attenuates cadmium induced hepatotoxicity in Swiss albino mice

Cadmium (Cd) is a soft, malleable bluish-white metal with low melting point, a ubiquitous heavy metal and an environmental pollutant, found in soil, water and air. The presence of Cd in the components of the environment such as air, soil and groundwater is to a large part due to human activity, and the general population is exposed mainly by contaminated drinking water or food. Manganese (Mn) is a component in many enzymes, which play an important role in counteracting oxidative stress. In vitro experiments have revealed the ability of Mn to scavenge oxygen free radicals generated in differently mediated lipid peroxidation (LPO) conditions. The aim of the present study was to investigate the in vivo preventive effect of Mn(2+) pre-treatment on acute Cd-intoxication with regard to oxidative stress biomarker and antioxidant defense system in liver of Swiss albino mice. On exposure to Cd a significant increase in LPO levels, decrease in thiol content and induction in glutathione metabolizing enzyme were observed. Mn pre-treatment attenuated the modulation caused in the above-mentioned parameters due to acute Cd exposure in mice. In conclusion, the results from this study demonstrate that the protective effect of Mn in Cd-induced systemic toxicity in mice. Further investigations are required on the relation between Mn accumulation and resistance to oxidative stress and on the factors influencing Mn/Cd transport in rodents are needed to elucidate the molecular basis of this protective effect.

Perspectives in endocrine toxicity of heavy metals--a review

An attempt has been made to review the endocrine/hormonal implications of a few environmentally significant metals, viz, lead, mercury, cadmium, copper, arsenic and nickel, in man and animals. Special emphasis has been given to the adrenals, thyroid, testis, ovary and pancreas. Toxic metals can cause structural and functional changes in the adrenal glands. Their effects on steroidogenesis have been reviewed. It has been reported that thyroid hormone kinetics are affected by a number of metallic compounds. Occupational exposure to a few of these metals can cause testicular injury and sex hormone disturbances. Protective effects of a few antioxidants on their reproductive toxicity have also been discussed. Information gathered on female reproductive toxicity of heavy metals shows that exposure to these metals can lead to disturbances in reproductive performance in exposed subjects. Certain metals can cause injury to the endocrine pancreas. Exposure to them can cause diabetes mellitus and disturb insulin homeostasis. The need to develop molecular markers of endocrine toxicity of heavy metals has been suggested. Overall information described in this review is expected to be helpful in planning future studies on endocrine toxicity of heavy metals.

Evaluation of bioaccumulation and toxic effects of copper on hepatocellular structure in mice

The present study was to evaluate the hepatotoxicity effects in mice exposed to copper (Cu) used as dietary supplements for 95 days. Cu-treated mice showed increased body weight, and no toxic symptoms were observed at the beginning, but the tendency gradually changed with progress of experiment. In the liver, beneficial metals [Cu, iron (Fe), zinc (Zn), manganese (Mn), and molybdenum (Mo)] were analyzed by flame atomic absorption spectrometry. The content of Cu maintained at the same level during the experiments, but not resulting in the imbalance of Fe, Zn, Mn, and Mo being distributed. The activities of alkaline phosphatase (AKP) and super oxidation dismutase (SOD) showed significantly improvement during the first 30 days in Cu-supplemented group (P<0.01) but declined rapidly from 30th to 60th days, and later, they stabilized and were not statistically significant compared with control (P>0.05). No statistically significant correlation of ceruloplasmin (CPL) activity was appreciated during the experiment. The histopathological and ultrastructural abnormalities changes were observed in the liver of mice including vacuolar degeneration, necrosis, karyorrhexis, and endolysis. Many hepatocytes showed increased collagenic fibers, appearance of triglyceride droplets, and swollen mitochondria due to oral route of copper, which may lead to lipid peroxidation and free radicals. In conclusion, our study showed that exposure to copper influenced behavioral pattern and body weight, affected several enzymatic activities, and led to the physiological and considerable structural changes in the liver of mice. The public should pay more attention to avoid being exposed to copper.

Manganese-induced effects on cerebral trace element and nitric oxide of Hyline cocks

Exposure to Manganese (Mn) is a common phenomenon due to its environmental pervasiveness. To investigate the Mn-induced toxicity on cerebral trace element levels and crucial nitric oxide parameters on brain of birds, 50-day-old male Hyline cocks were fed either a commercial diet or a Mn-supplemented diet containing 600, 900, 1,800 mg kg(-1). After being treated with Mn for 30, 60, and 90 days, the following were determined: the changes in contents of copper (Cu), iron (Fe), zinc (Zn), calcium (Ca), selenium (Se) in brain; inducible nitric oxide synthase-nitric oxide (iNOS-NO) system activity in brain; and histopathology and ultrastructure changes of cerebral cortex. The results showed that Mn was accumulated in brain and the content of Cu and Fe increased. However, the levels of Zn and Se decreased and the Ca content presented no obvious regularity. Exposure to Mn significantly elevated the content of NO and the expression of iNOS mRNA. Activity of total NO synthase (T NOS) and iNOS appeared with an increased tendency. These findings suggested that Mn exposure resulted in the imbalance of cerebral trace elements and influenced iNOS in the molecular level, which are possible underlying nervous system injury mechanisms induced by Mn exposure.

Effect of Ocimum basilicum extract on cadmium-induced testicular histomorphometric and immunohistochemical alterations in albino rats

The present study examined the efficacy of Ocimum basilicum (basil) extract, a natural herb, with antioxidant properties, against testicular toxicity induced by cadmium (Cd), which is one of the most important toxic heavy metals. The intoxicated rats showed significant alterations in the testicular tissue including decreased seminiferous epithelium height and changes in the arrangement of spermatogenic layers. Hypospermatogensis with cytoplasmic vacuolization and pyknotic nuclei were observed. Intertubular hemorrahage and absence of spermatozoa were noted. Decreased cell proliferation was reflected by a decrease in Ki-67 expression, whereas the increase in apoptotic rate was associated with a decrease in the Bcl/Bax ratio. Concomitant treatment with aqueous basil extract led to an improvement in histological, morphometrical and immunohistochemical changes induced by Cd. The beneficial effects of basil extract could be attributed to its antioxidant properties.

Manganese-induced effects on testicular trace element levels and crucial hormonal parameters of Hyline cocks

Manganese (Mn) is an essential element required for normal development and reproduction. However, little is known about the reproductive toxicity of Mn in birds. To investigate the Mn-induced toxicity on testicular trace element levels and crucial hormonal parameters on male reproduction in birds, 50-day-old male Hyline cocks were fed either a commercial diet or a Mn-supplemented diet. The changes in contents of copper (Cu), iron (Fe), zinc (Zn), and calcium (Ca) in testis were detected. Hormonal parameters were evaluated including the levels of testosterone (T), luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4) in the serum. The mRNA levels of luteinizing hormone receptor (LHR) and follicle-stimulating hormone receptor (FSHR) were determined in this study. The results showed that Mn was accumulated in testis, and the content of Cu, Fe, Zn, and Ca decreased. Exposure to Mn significantly lowered the content of T, LH, FSH, and the mRNA expression levels of LHR and FSHR. Levels of T3 and T4 appeared with a decreased tendency, and TSH presented no obvious regularity. It indicated that Mn exposure resulted in the disbalance of testicular trace elements and influenced hormone levels in the molecular level, which may be possible underlying reproductive toxicity mechanism induced by Mn.

Effects of xenobiotics on total antioxidant capacity

The objective of this article was to review the effects of xenobiotics on total antioxidant capacity (TAC). Measurement of TAC is appropriate for evaluation of the total antioxidant defenses of blood, cells, and different kinds of tissues and organs. TAC is reduced by alcoholism, smoking, and exposure to radiation, herbicides, carbon monoxide, carbon tetrachloride, lead, arsenic, mercury, cadmium, aluminum, and other toxic elements. The test is also an important tool in evaluating environmental and occupational exposure.

Minocycline increases the life span and motor activity and decreases lipid peroxidation in manganese treated Drosophila melanogaster

The objective of this study was to investigate the effect of Minocycline in the life span, motor activity, and lipid peroxidation of Drosophila melanogaster treated with manganese. Two days after emerging from the pupa male wild-type D. melanogaster were fed for 13 days with corn media containing 15 mM manganese. Then, they were divided in six groups of 300 flies each: group (a) remained treated with manganese (Mn group); group (b) began treatment with Minocycline (0.05 mM) (Mn-Minocycline group); group (c) received no additional treatment (Mn-no treatment group); group (d) simultaneously fed with manganese and Minocycline (Mn+Minocycline group). Additionally, a control (group e) with no treatment and another group (f) fed only with Minocycline after emerging from the pupa were added. All the manganese treated flies (group a) were dead on the 25th day. The life span in group f (101.66±1.33 days, mean S.E.M.) and of group b (97.00±3.46 days) were similar, but in both cases it was significantly higher than in group e (68.33±1.76 days), group c (67.05±2.30 days) and in those of group d (37.33±0.88). Manganese (groups a and d) decreased motor activity in D. melanogaster. In the Minocycline fed flies (groups b and f) a higher motor activity was detected. In Mn-Minocycline and Mn+Minocycline treated flies a significant decrease of MDA levels was detected when compared to the Minocycline group indicating that Minocycline and Mn appear to have a synergistic effect. In conclusion, Minocycline increased the life span and motor activity and decreased MDA formation of manganese treated D. melanogaster, probably by an inhibition of the production of reactive oxygen species. Manganese also exerted an antioxidant effect as shown by the significant decrease of MDA levels when compared to control flies.

CdSe quantum dot (QD)-induced morphological and functional impairments to liver in mice

Quantum dots (QDs), as unique nanoparticle probes, have been used in in vivo fluorescence imaging such as cancers. Due to the novel characteristics in fluorescence, QDs represent a family of promising substances to be used in experimental and clinical imaging. Thus far, the toxicity and harmful health effects from exposure (including environmental exposure) to QDs are not recognized, but are largely concerned by the public. To assess the biological effects of QDs, we established a mouse model of acute and chronic exposure to QDs. Results from the present study suggested that QD particles could readily spread into various organs, and liver was the major organ for QD accumulation in mice from both the acute and chronic exposure. QDs caused significant impairments to livers from mice with both acute and chronic QD exposure as reflected by morphological alternation to the hepatic lobules and increased oxidative stress. Moreover, QDs remarkably induced the production of intracellular reactive oxygen species (ROS) along with cytotoxicity, as characterized by a significant increase of the malondialdehyde (MDA) level within hepatocytes. However, the increase of the MDA level in response to QD treatment could be partially blunted by the pre-treatment of cells with beta-mercaptoethanol (β-ME). These data suggested ROS played a crucial role in causing oxidative stress-associated cellular damage from QD exposure; nevertheless other unidentified mediators might also be involved in QD-mediated cellular impairments. Importantly, we demonstrated that the hepatoxicity caused by QDs in vivo and in vitro was much greater than that induced by cadmium ions at a similar or even a higher dose. Taken together, the mechanism underlying QD-mediated biological influences might derive from the toxicity of QD particles themselves, and from free cadmium ions liberated from QDs as well.