Influence of chronic cadmium exposure on the tissue distribution of copper and zinc and oxidative stress parameters in rats.

The aim of this study was to investigate the effect of oral cadmium (Cd) intoxication on the antioxidant response and its relationship with essential bioelements like copper (Cu) and zinc (Zn). The experimental group was chronically exposed to Cd daily for 8 weeks via consumption of water containing 15 ppm cadmium chloride. Cu, Zn, and Cd concentrations and oxidative stress parameters were analyzed in liver, kidney, and heart tissues. Exposure to Cd led to a significant decrease in the activities of superoxide dismutase in all considered samples while a significant increase in the activity of glutathione peroxidase except for the kidney. We found a significant increase in malondialdehyde concentration in the tissues except for heart. Also oral administration of Cd caused a significant reduction of Zn and Cu in the tissues. Our results allow us to hypothesize that higher Cd concentration in the tissues causes oxidative stress by increasing malondialdehyde as a means of altering antioxidant defense system and deterioration of bioelements in rat liver, kidney, and heart. In addition, further studies are needed to explain the effect of long-term, low-dose exposure to Cd on distribution of bioelements and its relationship with oxidative stress.

Role of ATP-dependent K channels in the effects of erythropoietin in renal ischaemia injury.

BACKGROUND & OBJECTIVES: Erythropoietin (EPO) has cytoprotective and anti-apoptotic effects in pathological conditions, including hypoxia and ischaemia-reperfusion injury. One of the targets to protect against injury is ATP-dependent potassium (KATP ) channels. These channels could be involved in EPO induced ischaemic preconditoning like a protective effect. We evaluated the cell cytoprotective effects of EPO in relation to KATP channel activation in the renal tubular cell culture model under hypoxic/normoxic conditions. METHODS: Dose and time dependent effects of EPO, KATP channel blocker glibenclamide and KATP channel opener diazoxide on cellular proliferation were evaluated by colorimetric assay MTT [3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide] under normoxic and hypoxic conditions in human renal proximal tubular cell line (CRL-2830). Evaluation of the dose and time dependent effects of EPO, glibenclamide and diazoxide on apoptosis was done by caspase-3 activity levels. Hypoxia inducible factor-1 alpha (HIF-1 α) mRNA levels were measured by semi-quantative reverse transcription polymerase chain reaction (RT)-PCR. Kir 6.1 protein expresion was evalutaed by Western blot. RESULTS: Glibenclamide treatment decreased the number of living cells in a time and dose dependent manner, whereas EPO and diazoxide treatments increased. Glibenclamide (100 µM) treatment significantly blocked the anti-apoptotic effects of EPO (10 IU/ml) under both normoxic and hypoxic conditions. EPO (10 IU/ml) and diazoxide (100 µM) treatments significantly increased (p <0.01) whereas glibenclamide decreased ( p<0.05) HIF-1 α mRNA expression. Glibenclamide significantly ( p<0.01) decreased EPO induced HIF-1 α mRNA expression when compared with the EPO alone group. INTERPRETATION & CONCLUSIONS: Our results showed that the cell proliferative, cytoprotective and anti-apoptotic effects of EPO were associated with KATP channels in the renal tubular cell culture model under hypoxic/normal conditions.

Involvement of galectin-3 in cadmium-induced cardiac toxicity.

OBJECTIVE: Accumulation of the wide spread environmental toxin cadmium (Cd) in tissues results in toxicity. Heart is one of the most effected tissues. Cd exposure induces inflammation in effected tissues. The present study was focused to evaluate roles of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) in Cd toxicity and their relationships with galectin-3 levels. METHODS: In this experimental study, male Wistar rats were divided randomly to control and experimental groups. Experimental group was exposed to Cd at the dose of 15 ppm for 8 weeks (n=10/group). Inflammatory status in hearts was evaluated with measurement of tissue TNF-α and IL-6 levels. Histopathological examination of heart was carried out by light microscopy. Heart tissue caspase-3 level was used to identify apoptosis. Tissue galectin-3 level was evaluated by ELISA. Statistical difference between groups was evaluated by unpaired Student t-test, correlation was analyzed by Pearson's test. RESULTS: Heart sizes were increased after Cd toxicity. A significant increase in galectin-3 tissue levels was seen after Cd toxicity, this was accompanied with a significant increase in the TNF-α (control: 402±39, Cd: 793±26 pg/g tissue, p<0.001) and IL-6 (control: 150±78, Cd: 325±65 pg/g tissue, p<0.001) levels. Histopathological examination under light microscope suggested a combination of ongoing necrosis and apoptosis. Increased caspase-3 levels were measured after Cd toxicity (control: 12±2, Cd: 18±3 pmol/µg/min, p<0.001). CONCLUSION: Chronic Cd administration induces inflammation and apoptosis in rat hearts. Cadmium causes increased galectin-3 production from heart tissue. The formation of TNF-α due to Cd exposure may likely trigger this mechanism.

Role of midkine in cadmium-induced liver, heart and kidney damage.

Accumulation of the widespread environmental toxin cadmium (Cd) in tissues results in toxicity. Cd, which can induce a broad spectrum of biological effects, is a toxic substance and is associated with inflammation and apoptosis. Midkine (MK) has fibrinolytic, antiapoptotic, transforming, angiogenetic and chemotactic activities. After Cd toxicity, we found increased MK expression in liver cells in an in vitro cell culture model. The aim of this study was to determine the possibility of relationship between tissue MK expression levels, tumor necrosis factor α(TNF-α) levels and apoptosis in a chronic Cd toxicity model in rats. Male Wistar rats were exposed to Cd at the dose of 15 parts per million (ppm) for 8 weeks. MK levels were measured in kidney, heart and liver tissue by enzyme-linked-immunosorbent assay (ELISA). MK messenger RNA (mRNA) expression was evaluated by RT-PCR. Tissue apoptosis level was evaluated with tissue caspase-3 activity levels. Accumulation of Cd in liver is higher than the kidney and heart. Cd-treated rats had significantly higher tissue TNF-α and caspase-3 levels when compared with the control rats (p < 0.001). MK mRNA and protein levels were also significantly upregulated in the Cd-treated group (p < 0.05, p < 0.001, respectively). When compared with apoptosis in tissues, it was more prominent in the liver than kidney and heart. MK level is found increased 3, 1.7 and 1.3× folds in liver, kidney and heart, respectively. Our results showed that chronic Cd administration induces inflammation and apoptosis in rat liver, kidney and heart. MK involved in damage mechanisms of Cd-induced tissues. Further studies will show the underlying mechanism of increased MK expression in Cd toxicity.

The effect of chronic cadmium toxicity on blood pressure and plasma viscosity.

Cadmium (Cd) is a heavy metal which affects many systems in humans and animals as a consequence of environmental and industrial pollution. The aim of this study was to investigate the effect of chronic Cd toxicity on blood pressure and plasma viscosity. Experimental group rats were given doses that contained 15 ppm CdCl(2) in drinking water for 8 weeks. The systolic blood pressure and heart rate were measured from rats' tails and recorded by plethysmography every two weeks. Blood samples were drawn, Cd levels were determined by atomic absorption spectrophotometer and plasma viscosity values by viscometer. Blood Cd levels were found to be significantly higher in the experimental group compared to the control group (p < 0.001). The whole blood analysis was made by an analyzer. Polymorphonuclear leukocytes and monocytes increased (p < 0.01) and lymphocyte number (p < 0.05) decreased in the experimental group. Viscosity values were 2.21 ± 0.54 and 1.62 ± 0.31 centipoises in the experimental and control groups, respectively (p < 0.001). In the experimental group, changes in systolic blood pressure between weeks were significant (p < 0.001) and were found to be correlated with plasma viscosity (p < 0.001). In the experimental group, changes in heart rate between weeks were significant (p < 0.001). According to our findings, Cd toxicity may lead to an increase in blood pressure by increasing plasma viscosity.

Cadmium reduces contractile responses of rat duodenum, in vitro.

The present study focuses on the effects of cadmium in drinking water on rat duodenum contractility, in vitro. Two experimental groups (n = 10 each) were administered with 15 ppm cadmium chloride in their drinking water for 1 and 2 months, respectively. Two separate groups (n = 10 each) were maintained in similar conditions but received no cadmium and acted as controls. After the experimental period, the duodenal segment responses were measured by means of an isotonic transducer. The average peak amplitude of acetylcholine-induced contractions was significantly decreased in both cadmium-treated groups. Incubation of duodena from the cadmium-free controls with atropine or in a calcium-free medium resulted in reduced contractility that was undistinguishable from that of the cadmium-treated rats. Cadmium reduces the contractile response apparently by directly or indirectly decreasing cellular calcium influx.

Midkine secretion protects Hep3B cells from cadmium induced cellular damage.

AIM: To evaluate role of midkine secretion during Cadmium (Cd) exposure in the human hepatocyte cell line Hep3B cells. METHODS: Different dosages of Cd (0.5-1-5-10 microg/mL) were applied to Hep3B cells and their effects to apoptosis, lactate dehydrogenase (LDH) leakage and midkine secretion were evaluated as time dependent manner. Same experiments were repeated with exogenously applied midkine (250-5000 pg/mL) and/or 5 microg/mL Cd. RESULTS: Cd exposure induced prominent apoptosis and LDH leakage beginning from lower dosages at the 48th h. Cd induced midkine secretion with higher dosages (P < 0.001), (control, Cd 0.5-1-5-10 microg/mL respectively: 1123 +/- 73, 1157 +/- 63, 1242 +/- 90, 1886 +/- 175, 1712 +/- 166 pg/mL). Exogenous 500-5000 pg/mL midkine application during 5 microg/mL Cd toxicity prevented caspase-3 activation (control, Cd toxicity, 250, 500, 1000, 2500, 5000 pg/mL midkine+ Cd toxicity, respectively: 374 +/- 64, 1786 +/- 156, 1545 +/- 179, 1203 +/- 113, 974 +/- 116, 646 +/- 56, 556 +/- 63 cfu) LDH leakage and cell death in Hep3B cells (P < 0.001). CONCLUSION: Our results showed that midkine secretion from Hep3B cells during Cd exposure protects liver cells from Cd induced cellular damage. Midkine has anti-apoptotic and cytoprotective role during Cd toxicity. Further studies are needed to explain the mechanism of midkine secretion and cytoprotective role of midkine during Cd exposure. Midkine may be a promising therapeutic agent in different toxic hepatic diseases.

The effects of chronic cadmium toxicity on the hemostatic system.

Cadmium, a highly toxic heavy metal, is distributed widely in the general environment. The characteristic clinical manifestations of chronic cadmium intoxication include renal proximal tubular dysfunction, osteomalacia and anemia. Accumulating evidence suggests that cadmium toxicity may also affect various organs such as the liver, lung, testis and hematopoietic system. The aim of this study was to determine the effect of chronic cadmium exposure on the anticoagulant system in rats. Fourty-five adult Wistar albino rats were randomly allocated into 2 groups. While the control group was given tap water, the animals in the cadmium group were treated with 15 ppm CdCl(2) for 4 weeks. Blood cadmium concentration, prothrombin time, activated partial thromboplastin time, plasma protein C and antithrombin activity, and platelet count were determined in the rats. Blood cadmium concentrations increased in the experiment group compared to the control group (p < 0.001). Results also show that cadmium exposure shortened prothrombin time (p < 0.05) and activated partial thromboplastin time (p < 0.01) in rats. Protein C (p < 0.001) and antithrombin (p < 0.001) decreased to statistically significantly lower levels in rat plasma after cadmium exposure when compared to the control group. When the number of thrombocytes was compared between 2 groups, a decrease was observed in the group treated with CdCl(2), which was, however, not statistically significant (p > 0.05). In conclusion, when the parameters of the hemolytic system are considered, the decrease in protein C and antithrombin activities and the shortening of prothrombin time and activated partial thromboplastin time suggests the presence of a hypercoagulable state during chronic cadmium intoxication. Therefore, it may be stated that chronic cadmium toxicity sets the stage for hypercoagulation and hence increases the risk of thrombosis.

Trace element concentrations and superoxide dismutase and catalase activities in benign and malignant larynx tumors.

The plasma and erythrocyte levels of zinc, copper, and magnesium and the activities of red-cell copper-zinc superoxide dismutase (Cu/Zn-SOD) and catalase (CAT) were determined in patients with benign and malignant tumors of the larynx. Blood samples from patients and healthy controls were drawn using heparinized tubes. The erythrocyte Cu/Zn-SOD and CAT activities were determined spectrophotometrically and the zinc, copper, and magnesium concentrations were determined in erythrocyte and plasma by atomic absorption spectrometry. Variance analysis was employed in the statistical evaluation of the findings. There was a significant increase in red-cell Cu/Zn-SOD activity in the subjects with malignant and benign tumors compared to controls (p<0.001). The CAT activity increased only in the benign tumor group (p<0.01). The plasma zinc concentrations were significantly lower in the malignant tumor group (p<0.05) and significantly higher in the benign tumor group (p<0.01). The erythrocyte copper concentrations were significantly lower in both benign and malignant tumor groups (p<0.001). The plasma copper and magnesium and the erythrocyte magnesium concentrations did not show significant differences relative to controls (p>0.05). The increases in the activities of SOD and CAT activities and the changes in trace elements concentrations can indicate the presence of increased reactive oxygen species that might play a part in the pathogenesis larynx tumors.

Effects of inflammation and antiinflammatory treatment on serum trace elements concentrations.

We investigated the serum concentrations of zinc and copper during the inflammatory process together with the effect of treatment with a nonsteroid anti-inflammatory agent on these trace elements concentrations. In the present study, we used 92 guinea pigs, 12 of which constituted the control group; the remaining 80 were the experimental group. To start with, proquazone (as anti-inflammatory agent) was administered orally to 40 guinea pigs of the experimental group at 20-mg/kg doses 2 h before the surgery. Throughout the experimental period, the above dose was administered to the animals twice a day. We produced inflammation in all animals of the experimental group by using carrageenan (inflammatory agent) dropped into mandibular surgical defects. Serum concentrations of zinc and copper were determined by atomic absorption spectrophotometry in both groups at the 6th, 48th, 120th, 168th, and 240th h. The serum zinc concentrations of the carrageenan-administered group decreased significantly (p<0.01). When comparing the serum zinc concentrations of the carrageenan plus proquazone-administered group with those of control group, the decrease (p<0.05) at the 6th, 48th, and 120th h were statistically significant. When the copper serum concentrations of the carrageenan-administered group were compared with those of the control group, at the 48th, 120th, and 168th h, a statistically significant increase (p<0.01) was observed. However, there was no significant change in the carrageenan plus proquazone-administered group at the 168th and 240th h. As a result decreased, whereas serum copper concentrations increased. The alterations in zinc concentrations were more rapid than those in copper concentrations, but the administration of proquazone slowed the rate of decrease in serum zinc concentrations.