Changes in Endogenous Essential Metal Homeostasis in the Liver and Kidneys during a Six-Month Follow-Up Period after Subchronic Cadmium Exposure.

Cadmium (Cd) is one of the most dangerous environmental pollutants. Its mechanism of action is multidirectional; among other things, it disrupts the balance of key essential elements. The aim of this study was to assess how cumulative exposure to Cd influences its interaction with selected essential elements (Cu, Zn, Ca, and Mg) in the kidney and liver during long-term observation (90 and 180 days) after subchronic exposure of rats (90 days) to Cd at common environmental (0.09 and 0.9 mg Cd/kg b.w.) and higher (1.8 and 4.5 mg Cd/kg b.w.) doses. Cd and essential elements were analyzed using the F-AAS and GF-AAS techniques. It was shown that the highest bioaccumulation of Cd in the kidney occurred six months after the end of exposure, and importantly, the highest accumulation was found after the lowest Cd dose (i.e., environmental exposure). Organ bioaccumulation of Cd (>21 µgCd/g w.w. in the kidney and >6 µgCd/g w.w. in the liver) was accompanied by changes in the other studied essential elements, particularly Cu in both the kidney and liver and Zn in the liver; these persisted for as long as six months after the end of the exposure. The results suggest that the critical concentration in human kidneys (40 µgCd/g w.w.), currently considered safe, may be too high and should be reviewed, as the observed long-term imbalance of Cu/Zn in the kidneys may lead to renal dysfunction.

An Assessment of Metallothionein-Cadmium Binding in Rat Uterus after Subchronic Exposure Using a Long-Term Observation Model.

Cadmium (Cd) is an environmental pollutant known to pose a public health issue. The mechanism of Cd toxicity on the uterus, including the protective role of metallothionein (MT), is still not fully understood. The aim of the study was to evaluate the degree of MT-Cd binding in the uterus of rats exposed per os to Cd at daily doses of 0.09, 0.9, 1.8 and 4.5 mg Cd/kg b.w. for 90 days. To assess the permanence of the bond, the rats were observed over long observation periods: 90 and 180 days after termination of exposure. Additionally, uterine concentration of Zn, Cu, Ca, Mg was determined. Cd leads immediately after exposure to a max. 30-fold increase in the concentration of Cd in the uterus, with only small amounts being bound to MT. After 90 days following termination of exposure, and especially after 180 days, an increase in MT-Cd concentration was noted for the three highest doses; even so, the degree of Cd binding by MT was still small. Additionally, the accumulation of Cd in the uterus disturbs the homeostasis of determined essential elements, manifested by a significant increase in Cu concentration and a decrease in Zn, Mg and Ca, especially 180 days after termination of exposure. The obtained results indicate that MT has only a slight protective role in the uterus and that Cd ions may have harmful effects not related to MT: directly on the uterine tissue, and indirectly by disturbing the homeostasis of its essential elements.

Hexachloronaphthalene (HxCN) impairs the dopamine pathway in an in vitro model of PC12 cells.

Among polychlorinated naphthalenes (PCNs), listed by the Stockholm convention as Persistent Organic Pollutants (POPs), hexachloronaphthalenes are considered the most toxic and raise the highest concern. Of these, 1,2,3,5,6,7-hexachloronaphthalanene (PCN67) is considered the main congener affecting human health due to its hepatotoxicity and its ability to disturb the reproductive, endocrine, and hematological systems. It is also prevalent in human serum/plasma, milk, and adipose tissue. However, little is known about its neurotoxicity, despite the fact that anorectic effects have been observed in workers occupationally exposed to PCNs and in animal research on PCN67. Since dopamine is involved in many aspects of food intake, the aim of this study was to confirm whether PCN67 affects dopamine synthesis in differentiated PC12 cells, a widely used model of neurosecretion. Our results show that exposure to PCN67 resulted in diminished dopamine content and release. Moreover, PCN67 also affected the expression of tyrosine hydroxylase and lowered the expression of vesicular monoamine transporter 1 (VMAT1). In addition, significantly lower expression of antioxidant enzymes, including catalase, glutathione peroxidase and copper/zinc superoxide dismutase, was observed in comparison to the vehicle. In conclusion, PCN67 appears to disturb dopaminergic transmission by altering tyrosine hydroxylation, reducing VMAT1 expression and impairing antioxidant protection. Our study provides a potential mechanism for how PCN67 may cause dopamine deficiency and contribute to neuronal death by affecting cellular antioxidant potency; however, this conclusion requires further research.

Age-Related Changes in Zinc, Copper and Selenium Levels in the Human Prostate.

Pathophysiological changes in the prostate gland-benign prostatic hyperplasia (BPH) and prostatic adenocarcinoma (PCa)-are closely related to the age of men. In the prostate gland, zinc is of particular importance for its proper functioning, especially with regard to the effects of hormonal disorders. The aim of this study was to evaluate zinc, copper and selenium concentrations in different parts of the prostate gland in relation to age and the nature of pathological changes. Zinc and copper were determined by the AAS method and selenium by the spectrofluorometric method. The concentration of zinc in the central part of the prostate increases with age, and in patients over 36 years it is twice as high as in the peripheral part, where no increase in the level of this element was observed with the age of patients. The above data confirm a possible influence of zinc on the formation of PCa (located mostly in the peripheral part of the prostate, with low levels of zinc) and BPH in the central part where the levels of this element are the highest. The results apparently confirm the disturbed homeostasis of zinc and other essential elements in the etiology of BPH and PCa.

An assessment of the estrogenic and androgenic properties of tetra- and hexachloronaphthalene by YES/YAS in vitro assays.

Many persistent organic pollutants (POPs) exhibit endocrine disrupting activity but studies on some POPs, e.g., polychlorinated naphthalenes (PCNs), are very scarce. The present study investigates the (anti)estrogenic and (anti)androgenic activities of 1,2,3,5,6,7-hexachloronaphthalane (PCN67) and 1,3,5,8-tetrachloronaphthalene (PCN43) using the yeast estrogen and androgen reporter bioassays. Among the tested substances, antiestrogenic response was only shown by PCN67. The strongest inhibition of estrogenic activity (up to 17.4%) was observed in the low concentration ranges (5 pM - 0.5 nM) in the presence of 1.5 nM 17ß-estradiol. Both tested compounds showed partial estrogenic activity with a hormetic-type response. However, both studied chemicals showed strong antiandrogenic effects: their potency in the presence of 100 nM 17ß-testosterone for PCN43 (IC50 = 2.59 µM) and PCN67 (IC50 = 3.14 µM) was approximately twice that of the reference antiandrogen flutamide (IC50 = 6.14 µM). It cannot be excluded that exposure to PCNs, together with other endocrine disrupting chemicals (EDCs), may contribute to the deregulation of sex steroid hormone signaling.

The Role of Zinc in Selected Female Reproductive System Disorders.

Zinc is an essential microelement that plays many important functions in the body. It is crucial for the regulation of cell growth, hormone release, immunological response and reproduction. This review focuses on its importance in the reproductive system of women of reproductive and postmenopausal ages, not including its well described role in pregnancy. Only recently, attention has been drawn to the potential role of zinc in polycystic ovary syndrome (PCOS), dysmenorrhea, or endometriosis. This review is mainly based on 36 randomized, controlled studies on reproductive, pre- and post-menopausal populations of women and on research trying to explain the potential impact of zinc and its supplementation in the etiology of selected female reproductive system disorders. In women with PCOS, zinc supplementation has a positive effect on many parameters, especially those related to insulin resistance and lipid balance. In primary dysmenorrhea, zinc supplementation before and during each menstrual cycle seems to be an important factor reducing the intensity of menstrual pain. On the other hand, little is known of the role of zinc in endometriosis and in postmenopausal women. Therefore, further studies explaining the potential impact of zinc and its supplementation on female reproductive system would be highly advisable and valuable.

Hexachloronaphthalene Induces Mitochondrial-Dependent Neurotoxicity via a Mechanism of Enhanced Production of Reactive Oxygen Species.

Hexachloronaphthalene (PCN67) is one of the most toxic among polychlorinated naphthalenes. Despite the known high bioaccumulation and persistence of PCN67 in the environment, it is still unclear to what extent exposure to these substances may interfere with normal neuronal physiology and lead to neurotoxicity. Therefore, the primary goal of this study was to assess the effect of PCN67 in neuronal in vitro models. Neuronal death was assessed upon PCN67 treatment using differentiated PC12 cells and primary hippocampal neurons. At 72 h postexposure, cell viability assays showed an IC50 value of 0.35 µg/ml and dose-dependent damage of neurites and concomitant downregulation of neurofilaments L and M. Moreover, we found that younger primary neurons (DIV4) were much more sensitive to PCN67 toxicity than mature cultures (DIV14). Our comprehensive analysis indicated that the application of PCN67 at the IC50 concentration caused necrosis, which was reflected by an increase in LDH release, HMGB1 protein export to the cytosol, nuclear swelling, and loss of homeostatic control of energy balance. The blockage of mitochondrial calcium uniporter partially rescued the cell viability, loss of mitochondrial membrane potential (ΔΨ m), and the overproduction of reactive oxygen species, suggesting that the underlying mechanism of neurotoxicity involved mitochondrial calcium accumulation. Increased lipid peroxidation as a consequence of oxidative stress was additionally seen for 0.1 µg/ml of PCN67, while this concentration did not affect ΔΨ m and plasma membrane permeability. Our results show for the first time that neuronal mitochondria act as a target for PCN67 and indicate that exposure to this drug may result in neuron loss via mitochondrial-dependent mechanisms.

The Effect of Zinc, Selenium, and Their Combined Supplementation on Androgen Receptor Protein Expression in the Prostate Lobes and Serum Steroid Hormone Concentrations of Wistar Rats.

BACKGROUND: Zinc (Zn) and selenium (Se) play a well-documented role in cancer prevention (e.g., for prostate cancer), and their combined supplementation is often given as a recommended prophylactic agent. The aim of the study was to determine the influence of Zn and/or Se supplementation on the androgen receptor (AR) in the prostate lobes and the serum selected hormone concentrations; a hitherto unresearched topic. METHODS: Male rats (n = 84) were administered with Zn and/or Se intragastrically for up to 90 days. The effects of administration on the tested parameters were checked after 30 and 90 days of administration and additionally, 90 days after the end of 90 day administration. RESULTS: Zn alone leads to an increase in serum testosterone concentrations, while the protein expression of AR in both parts of the prostate increases. Combined administration of Zn and Se eliminates the effect of Zn, which may suggest that these two elements act antagonistically. Se supplementation alone results in the same level of AR protein expression in administration and 90 days after administration periods. CONCLUSION: This paper presents the first report of the influence of Zn and/or Se supplementation on the protein expression of AR in the prostate. Our findings seem to indicate that simultaneous supplementation of both elements may be ineffective.

Subchronic Exposure to Cadmium Causes Persistent Changes in the Reproductive System in Female Wistar Rats.

Cadmium (Cd) is an environmental toxicant and endocrine disruptor in humans and animals, and recent studies have illustrated that the uterus is exceedingly sensitive to Cd toxicity. The aim of the study was to investigate the influence of subchronic (90 days) oral Cd exposure in daily doses of 0.09-4.5 mg/kg b.w. on the balance of sex hormones by estimating estradiol (E2) and progesterone (P) concentrations in the uterus and plasma in comparison with the effects of 17ß-E2. Additionally, the uterine weight, histopathological changes in the uterus and ovaries, the regularity of the estrous cycle, Cd bioaccumulation in uterine tissue, and selected biochemical parameters of oxidative stress were determined. A long period of observation (three and six months following the administration period) was used to assess whether the existing effects are reversible. The lowest dose of Cd caused effects similar to 17ß-E2: an increase of E2 concentration in the uterus, endometrial epithelium thickness, and disturbed estrous cycle with estrus phase prolongation. The obtained results suggest that Cd causes nonlinear response. Higher doses of Cd caused a significant decrease in E2 concentration in the uterus and plasma, estrous cycle disturbances, endometrium atrophy, and structural damage in the ovaries. This dose additionally induces lipid peroxidation in the uterine tissues. It is noteworthy that a prolonged time of observation after terminating the exposure showed persistent changes in the concentration of E2 in uterine tissue, as well as alterations in estrous cycle phases, and an increase in lipid peroxidation in the uterus. Moreover, significant positive correlations between the plasma E2 concentration and endometrial epithelium thickness in all studied groups were found. In summary, subchronic oral Cd exposure of female rats may result in impaired fertility processes.

The effect of repeated cadmium oral exposure on the level of sex hormones, estrous cyclicity, and endometrium morphometry in female rats.

Cadmium (Cd) is regarded as a potential endocrine disruptor. However, the exact mechanism by which this metal may interfere with the reproductive system has not yet been elucidated. The present study aimed to investigate the effect of subacute Cd oral administration at daily doses of 0.09, 1.8, and 4.5 mgCd/kg b.w. and the impact of Cd on sex hormones (estradiol (E2) and progesterone (P)) in the plasma and uterus, as well as on estrous cyclicity and histopathological changes in uterine and ovary in female rats after terminating the exposure and after a prolonged observation period (3 months). Moreover, Cd bioaccumulation in the uterine and brain tissue of rats was analyzed. The study revealed that oral Cd exposure induced changes in the plasma levels of steroid hormones: decrease in E2 and increase in P after the highest dose of Cd. Probably, for the first time, it was evidenced that circulation sex hormone disturbances in Cd-exposed rats caused irregular estrous cycle, persisting for 3 months after exposure termination; no alterations in these hormone levels in uterine tissue were noted. Cd did not induce estradiol-like hyperplasia of endometrium, but resulted in endometrial edema irrespective of the dose, and caused damage of the ovaries after the highest dose. In summary, subacute oral exposure of female rats to Cd may lead to long-term disturbances in reproductive system.

Estimation of cutoff values of cotinine in urine and saliva for pregnant women in Poland.

Setting appropriate cutoff values and the use of a highly sensitive analytical method allow for correct classification of the smoking status. Urine-saliva pairs samples of pregnant women in the second and third trimester, and saliva only in the first trimester were collected. Offline SPE and LC-ESI-MS/MS method was developed in the broad concentration range (saliva 0.4-1000 ng/mL, urine 0.8-4000 ng/mL). The mean recoveries were 3.7 ± 7.6% for urine and 99.1 ± 2.6% for saliva. LOD for saliva was 0.12 ng/mL and for urine 0.05 ng/mL; LOQ was 0.4 ng/mL and 0.8 ng/mL, respectively. Intraday and interday precision equaled, respectively, 1.2% and 3.4% for urine, and 2.3% and 6.4% for saliva. There was a strong correlation between salivary cotinine and the uncorrected cotinine concentration in urine in the second and third trimesters of pregnancy. The cutoff values were established for saliva 12.9 ng/mL and urine 42.3 ng/mL or 53.1 µg/g creatinine with the ROC curve analysis. The developed analytical method was successfully applied to quantify cotinine, and a significant correlation between the urinary and salivary cotinine levels was found. The presented cut-off values for salivary and urinary cotinine ensure a categorization of the smoking status among pregnant women that is more accurate than self-reporting.

[Biomarkers of occupational and environmental exposure to benzene and styrene determinated by LC-MS/MS]. / Oznaczanie biomarkerów narazenia zawodowego i srodowiskowego na benzen i styren z zastosowaniem techniki LC-MS/MS.

BACKGROUND: Based on the studies performed a sensitive and simple method for the determination of benzene and styrene metabolites in urine has been developed. The developed procedure can be used for biological monitoring of occupational and environmental exposure. MATERIAL AND METHODS: Urine samples for the determination of styrene metabolites (phenylglyoxylic acid--PGA and mandelic acid--MA) were only acidified with formic acid, while those for the determination of benzene metabolite (S-phenyl-mercapturic acid--S-PMA) were additionally extracted with ethyl acetate. The measurement was performed by high performance liquid chromatography--tandem mass spectrometry (HPLC-MS/MS). The quality of our analysis was verified using internal and external quality control. RESULTS: Limit of detection for S-PMA was 0.33 microg/l, for MA--60 microg/l and for PGA--40 microg/l; precision was 2-3% and recovery 94-98%. CONCLUSIONS: The method for the quantification of benzene and styrene metabolites can be used for biological monitoring of occupational and environmental exposure.