Poster
# 38
Poster |
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6th Internet World Congress for Biomedical Sciences |
Peter Massanyi(1), Laszlo Bardos(2), Robert Toman(3), Svatoslav Hluchy(4), Jaroslav Kovacik(5), Norbert Lukac(6)
(1)(3)(4)(6)Slovak Agricultural University - Nitra. Slovakia
(2)University of Agricultural Sciences - Godollo. Hungary
(5)Slovak University of Agriculture - Nitra. Slovakia
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[Toxicology] |
[Reproduction Sciences] |
Concern about the constantly increasing environmental levels of heavy metals has stimulated interest in the study of toxic substances on life systems. Cadmium, one of these substances is a toxic, environmental pollutant that serves no biological function, and is therefore totally unwanted. Cadmium is chemically similar to zinc and occurs naturally with zinc and lead in sulfide ores. Some cadmium has been found in all natural materials that have been analyzed. High concentrations in air, water and soil are, however, commonly associated with industrial emission sources, particularly non-ferrous mining and metal refining (4).
Exposure to cadmium, via air and food, leads to renal tubular dysfunction. This is primarily a reabsorption defect in the proximal tubules and the critical effect of cadmium (4,5,13,14). There are also various effects on reproduction, causing follicular atresia (10), edematization of uterus (12) as well as degenerative alterations in testes (18). Cadmium mainly accumulates in kidneys and liver (4,9,15,16).
It is estabilished that vitamin A and cadmium are preferentially accumulated in the liver in high concentrations and that the metabolism of the vitamin is controlled in the liver (6). This suggests the possibility of an effect of cadmium on vitamin A metabolism.
The aim of our work was to investigate the distribution of cadmium (kidney, liver, muscle, spleen, testes, ovary) after an intraperitoneal (i.p.) administration and determine concentration of retinyl palmitate, retinol and ß-carotene in liver, kindey and testes in mice.
The experiments were conducted with 32 adult randombred ICR mice (Velaz Prague, Czech Republic) kept in plastic cages. Animals were divided into three groups (A, B, K). Mice in group A {11} were treated with a single i.p. cadmium dose of 0.25 mg CdCl2 (Sigma Chemical Company, St. Louis, MO, USA) per kg body weight, and were killed 48 hours later. Animals {11} in group B received a single i.p. dose of 0.5 mg CdCl2/kg b.w and were killed 48 hours after cadmium administration. The control group (K) consisted of 10 untreated mice. From all animals kidneys, liver, spleen, muscle (m. quadriceps femoris), ovaries and testes were collected. Concentrations of cadmium were determined by electrotermic atomic absorption spectrophotometry (Ekologické a veterinárne laboratóriá, Spišská Nová Ves, Slovak Republic, Unicam Solar 929). Aspiration method (4) of the ash solution with 1% HNO3, and then read at 228.8 µm wavelenght, following the Unicam AAS methods manual {1991} was used.
Concentrations of retinyl palmitate, retinol and ß-carotene were measured in all {32} animals. Retinoid content (retinyl palmitate, retinol) of kidney, liver and testes was extracted by n-hexane containing antioxidant (50 mg/l BHT). The extract was injected onto Si-100 S 10 CN column (BST Ltd., Budapest, Hungary). The elution parameters were as follows: mobile phase n-hexane: methanol {99.5 : 0.5}, flow rate 1.51 ml/min at 50 bar. The UV detection was carried out at 325 nm. Concentrations of b-carotene were measured in a similar arrangement but the detection was carried out at 450 nm. The peaks were identified by standard compounds : retinol (Sigma Chemical Company, St. Louis, MO, USA), retinyl palmitate (NBC, Cleveland, USA) and b-carotene (Merck, Darmstadt, FRG). The concentrations were determined from the peak-heights obtained by measuring the standard dilutions. From final data, basic statistical characteristics were calculated (mean, s.d.) and an analysis of variance by Sheffe´s test was completed for each variable.
After a single intraperitoneal administration cadmium mainly accumulated in the liver. This accumulation is dose dependent (Table 1.), and proved to be significant in comparison with the control group (P<0.001). In the kidney cadmium levels significantly increased similarly to the liver. When evaluating muscle (m. quadriceps femoris), the cadmium concentration was in control 0.125 mg/kg, higher in group A 0.144 mg/kg and the highest in group B - 0.636 mg/kg. Low levels of cadmium were found in spleen (0.026 - 0.414 mg/kg). In ovary, cadmium concentration in control animals was under the detectable limit of 0.01 mg/kg, but a highly significant (P<0.001) increase after cadmium administration (1.835; 2.134 mg/kg, respectively) is reported. Very similar accumulation of cadmium has been observed in testis, and is dose dependent.
Determination of concentration of retinyl palmitate, retinol and ß-carotene is listed in Table 2. No significant differences were found in the liver, and the concentration of retinyl palmitate was 16.96 - 18.18 µg/g. In kidney, the level of retinyl palmitate was 15.05 - 16.81 µg/g. Retinol concentration significantly decreased only in the group with higher cadmium concentration - group B (P<0.001). Level of ß-carotene was significantly decreased in kidney and testis in both Cd-treated groups (P<0.001). In testis all parameters were affected. Significant decrease of retinyl palmitate and retinol was found in group B (P<0.001) in comparison with the control group. Analysis of ß-carotene showed significant decrease (P<0.001) in both groups with cadmium administration (0.85 and 0.41 µg/g, respectively) in comparison with control animals (1.48 µg/g).
Table 1. Distribution of cadmium (mg/kg wet tissue) in mice
Organ Group K Group A Group B ------ ------------- ------------- -------------- Liver 0.052 ± 0.008 4.196 ± 0.357* 8.360 ± 0.711* Kidney 0.355 ± 0.030 2.382 ± 0.202* 2.709 ± 0.230* Muscle 0.125 ± 0.011 0.144 ± 0.021 0.636 ± 0.145 Spleen 0.026 ± 0.002 0.026 ± 0.004 0.414 ± 0.035 Ovary < 0.010 1.835 ± 0.156* 2.143 ± 0.182* Testis 0.333 ± 0.028 0.450 ± 0.038 0.738 ± 0.063* P<0.001 n = 32 Group K - control, untreated mice (n=10)
Group A - single i.p. dose 0.25 mg CdCl2.kg-1 (n=11)
Group B - single i.p. dose 0.5 mg CdCl2.kg-1 (n=11)
Table 2. Concentrations of retinyl palmitate, retinol and ß-carotene in mice liver, kidney and testis ( in µg/g)
Organ Liver Kidney Testis Group K ----------- ------------ ----------- RP 18.18 ± 1.85 15.05 ± 1.55 6.52 ± 0.78 ROL 26.39 ± 2.97 22.95 ± 1.98 8.21 ± 0.45 BC 1.95 ± 0.23 12.95 ± 1.33 1.48 ± 0.12 Group A RP 16.96 ± 1.55 16.81 ± 1.77 6.48 ± 0.78 ROL 15.61 ± 1.64 22.72 ± 2.23 8.27 ± 0.99 BC 3.19 ± 0.04 7.71 ± 0.77* 0.85 ± 0.09* Group B RP 17.55 ± 0.97 16.44 ± 1.98 3.03 ± 0.54* ROL 13.24 ± 1.35 16.95 ± 1.55* 5.24 ± 0.26* BC 3.24 ± 0.22 4.94 ± 0.58* 0.41 ± 0.05*RP = retinyl palmitate, ROL = retinol, BC = ß-carotene (all values are expressed in µg/g)
Group K - control, untreated mice (n=10); Group A - single i.p. dose 0.25 mg CdCl2.kg-1 (n=11); Group B - single i.p. dose 0.5 mg CdCl2.kg-1 (n=11) *P<0.001; n = 32
Cadmium mainly accumulates in liver and kidney (2,3,4,8,9,19,20). In control animals we have found higher cadmium concentration in kidney (0.355 mg/kg) than in liver (0.052 mg/kg). After single i.p. administration of cadmium we have observed higher cadmium levels in liver (4.196 and 8.360 mg/kg) than in kidney (2.382 and 2.709 mg/kg). This single exposure experiment has shown that initially, a very high proportion of the dose is found in the liver. With time there is a redistribution of cadmium from the liver to other tissues, particularly the kidneys as we found it in our earlier study in rabbits (4) and as it has been described by others (9). This is probably due to an efficient metallothionein synthesis in the liver. Cadmium bound to metallothionein may subsequently be released into plasma, filtered through renal glomeruli and reabsorbed in the tubuli. This is of significance for human and animals in high exposure situations. Even if the daily exposure ceases, the renal cadmium concentration may be maintained for a long time or even increase if sufficient amounts of cadmium are stored in the liver.
We report dose dependent accumulation of cadmium in testis as well as alterations in retinyl palmitate, retinol and ß-carotene concentration in testis. It has been reported that cadmium causes degeneration of the seminiferous epithelium (1,7,18). All biochemical and physiological changes known to occur in the testis at late time intervals following cadmium treatment are secondary to ischaemia rather than due to a direct effect of cadmium. Higher cadmium concentration also inhibits the motility of spermatozoa (11) and causes structural alterations of spermatozoa (7).
In this study significant decease of retinol (group B) and ß-carotene (both experimental groups) in kidney and retinyl palmitate (group B), retinol (group B) and ß-carotene (group A and B) in testis is reported. No significant differences were found in liver. ß-carotene is a provitamin of vitamin A. Cadmium in a long term study has been decsribed to induce significant decrease of serum vitamin A, while food intake and body weights remained unchanged (17). Absorption of vitamin A from the intestine, the release of newly absorbed vitamin A from the liver to serum, and the conversion of vitamin A to water soluble metabolites in the liver were not influenced by cadmium. These findings suggest that cadmium interfered with the release of vitamin A, especially stored vitamin A, to serum (17).
There may be many ways to interfere with the excretion mechanism of vitamin A to the serum. For example, the direct binding of cadmium with specific proteins essential for vitamin A excretion as retinol binding protein, prealbumin or vitamin A hydrolase, or the decrease in these proteins by cadmium and the destruction of excretion canals of cell organelles.
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[Toxicology] |
[Reproduction Sciences] |
