Toxic Action Of Cadmium Research Articles

The Mechanism of the Osteoprotective Action of a Polyphenol-Rich Aronia melanocarpa Extract during Chronic Exposure to Cadmium is Mediated by the Oxidative Defense System.

Recently, we demonstrated in a rat model that consumption of a polyphenol-rich extract obtained from the berries of Aronia melanocarpa could protect from cadmium-induced disorders in bone turnover and changes in bone mineral status. The aim of this study was to investigate whether the osteoprotective effect of this extract is mediated by the oxidative defense system. Enzymatic and nonenzymatic antioxidants, total antioxidative and oxidative status, hydrogen peroxide, and markers of oxidative protein, lipid, and DNA damage were determined in bone tissue at the distal femoral epiphysis of female Wistar rats receiving 0.1 % aqueous A.melanocarpa extract (prepared from the lyophilized commercial extract containing 65.74 % of polyphenols) as the only drinking fluid and/or cadmium in the diet (1 and 5 mg/kg) for 3, 10, 17, and 24 months. The total oxidative and antioxidative status of the serum was also evaluated. The administration of A.melanocarpa extract provided significant protection from cadmium-induced oxidative stress in the bone and serum, and from lipid peroxidation and oxidative damage to the protein and DNA in the bone tissue. Numerous correlations were noted between indices of the oxidative/antioxidative bone status and markers of bone metabolism previously assayed in the animals receiving A.melanocarpa extract. The results allow the conclusion that the ability of A.melanocarpa extract to mediate the oxidative defense system and prevent oxidative modifications of protein, lipid, and DNA in the bone tissue plays an important role in its osteoprotective action under exposure to cadmium. The findings provide further evidence supporting our suggestion that chokeberry may be a promising natural agent for protection against the toxic action of cadmium in women chronically exposed to this metal.

Effect of cadmium on collagen content and solubility in rat bone.

The toxic action of cadmium in the bone tissue is known, but its mechanisms are still unexplained. We examined whether Cd influences collagen content and its solubility in the femoral bone of three-week-old female rats exposed to 5 or 50 mg Cd/l in drinking water. Non-cross linked collagen was extracted with 0.5 M acetic acid, and two acid-insoluble collagen fractions were extracted with pepsin and 4.0 M guanidine hydrochloride, respectively. SDS/PAGE showed the presence of two collagen types, I and V, in all three extracted fractions. Exposure of rats to Cd for 6 months increased the amount of acid-soluble collagens type I and V and decreased the level of acid-insoluble collagens. The amount of total collagen extracted from the bones of rats exposed to 50 mg Cd/l was reduced by about 14% as compared to control and those intoxicated with 5 mg Cd/l. The solubility of type I bone collagen (determined as the percentage of acetic-soluble fraction of total collagen) was increased 2.9- and 3.0-fold in rats intoxicated with 5 and 50 mg Cd/l, respectively. Similarly, the solubility of type V collagen was increased 2.3- and 2.7-fold, respectively. Our results indicate that Cd treatment affects bone collagen by decreasing its content and increasing its solubility.

Effect of cadmium on collagen content and solubility in rat bone.

The toxic action of cadmium in the bone tissue is known, but its mechanisms are still unexplained. We examined whether Cd influences collagen content and its solubility in the femoral bone of three-week-old female rats exposed to 5 or 50 mg Cd/l in drinking water. Non-cross linked collagen was extracted with 0.5 M acetic acid, and two acid-insoluble collagen fractions were extracted with pepsin and 4.0 M guanidine hydrochloride, respectively. SDS/PAGE showed the presence of two collagen types, I and V, in all three extracted fractions. Exposure of rats to Cd for 6 months increased the amount of acid-soluble collagens type I and V and decreased the level of acid-insoluble collagens. The amount of total collagen extracted from the bones of rats exposed to 50 mg Cd/l was reduced by about 14% as compared to control and those intoxicated with 5 mg Cd/l. The solubility of type I bone collagen (determined as the percentage of acetic-soluble fraction of total collagen) was increased 2.9- and 3.0-fold in rats intoxicated with 5 and 50 mg Cd/l, respectively. Similarly, the solubility of type V collagen was increased 2.3- and 2.7-fold, respectively. Our results indicate that Cd treatment affects bone collagen by decreasing its content and increasing its solubility.

Action of cadmium on the gills of Carassius auratus L. in the presence of catabolic NH3

Histochemical changes of oxidative enzymes and cadmium uptake in the Carassius auratus gills were examined up to 7 days after a 87.6 μM cadmium exposure in very alkaline water in the presence and absence of catabolic ammonia. In the presence of catabolic NH3, the toxic action of cadmium is much more intense and determines a 20% survival of goldfish with a heavy increase in the excretion of mucus. Animals treated with cadmium only and controls survived in the order of 100%. More drastic histochemical alterations in the activity of oxidative enzymes (SDH, G-6-PDH, LDH) were documented in animals treated both with cadmium and ammonia, if compared with those treated with cadmium only. A reduction in the activity of enzymes after 24 h, a heavy increase of the LDH reaction after 72 h, and a strong increase after 7 days in the number of positive SDH cells (which correspond to chloride cells) were documented. After a hyperaccumulation at 24 h (returning afterwards to much lower values), at 7 days the cadmium uptake was higher in the animals treated both with cadmium and ammonia.

Influence of some metal chelators and light regimes on bioaccumulation and toxicity of Cd2+ in duckweed (Lemna gibba)

A factorial culture experiment was designed to investigate the influence of light regimes and of some metal chelators on the accumulation of cadmium by Lemna gibba L. The plants were grown in a complete nutrient solution containing Cd2+ concentrations ranging from 0 to 27 μM with or without EDTA, ethylenediamine‐N,N′‐bis‐(o‐hydroxyphenylacetic acid) (EDDHA) or salicylic acid. Each experiment was run for eight days in 18 h:6 h light:dark or continuous light. An increase in the Cd2+ concentration in plants and a simultaneous drop in accumulation efficiency (ratio of Cd2+ concentration in plants to the initial Cd2+ concentration in the nutrient solution) with increasing ambient Cd2+ levels was best represented by regression power curves. At the lowest Cd2+ concentration which caused a significant decrease in the relative growth rate of duckweed, there was a decrease in manganese and zinc and an increase in the iron level in the plants. EDDHA and EDTA protected in some cases against the toxic action of cadmium without preventing its uptake by plants. It was thus observed that 9 μM or higher levels of Cd2+ were toxic to Lemna gibba depending on the chelator and light regime. Duckweed grown in continuous light produced, in general, more dry matter and hence accumulated more cadmium.

Cadmium Contamination ofZea maysby Root Absorption

Absorption of radioactive cadmium (109Cd) and transport to leaves and stems was investigated in Zea mays under intensive and constant exposure early after germination and during flowering. Cadmium is readily taken up by the roots and about 20 percent is transported to parts above the ground, reaching also the reproductive organs. The separation of bound cadmium suggests that there is less binding on cell walls from cadmium taken up by the roots than that injected into the stems. Concentrations of K+ and Ca++ do not indicate a toxic action of cadmium on the plant under the conditions used.

Toxicité à long terme du cadmium administré à trés faible dose chez le rat: Réponse à l'agression par le froid

The toxic action of cadmium, as well as its interaction with a cold stress, has been studied on four groups of COBS-CD rats (10 ♂, 10 ♀), absorbing 0 (TT and TF) or 2.5 (CdT, CdF) ppm of cadmium (drinking water). After 12 months under observation, the TF and CdF groups were housed at +1°C for 48 hr. In the course of, or just after, this stress, various urinary parameters (volume, Na +, K +, urea, creatinine) and blood parameters (hemoglobin, Na +, K +, Ca 2+, Cl −, P i, urea, creatinine, blood sugar) were measured. In the CdT groups, cadmium was responsible for lower urea concentrations in urine (16%), and lower phosphate and creatinine in serum (16 and 10%). Under cold stress, treated animals (CdF) reacted differently than the control animals (TF): less polyuria, and no trace of hypokalemia, hypophosphatemia, and hyperglycemia; as opposed to the TF groups, the presence of hypercreatinemia (15%) and hypocalcemia (6%). These results hint at the existence of latent noxious effects related to the well-known toxicity of high doses of cadmium.