Lectin histochemistry for detecting cadmium-induced changes in the glycosylation pattern of rat placenta.

Cadmium (Cd) is an industrial and environmental pollutant that produces toxic effects on gametogenesis, pre- and post-implantation embryos, and the placenta. Because the effects of acute Cd intoxication on the placenta are not well understood, we investigated changes in its glycosylated components in Cd treated dams at days 4, 7, 10 and 15 of gestation using lectin histochemistry. CdCl2 was administered to pregnant rats; control animals received sterile normal saline. Placentas were processed for DBA, Con A, SBA, PNA, UEA-I, RCA-I and WGA lectin histochemistry to evaluate changes in the carbohydrate pattern of the placenta that might modify cell interactions and contribute to embryonic alterations. Lectin binding was analyzed in the yolk sac; trophoblast giant cells; trophoblast I, II and III; spongiotrophoblast cells and endovascular trophoblast cells in the chorioallantoic placenta. Our lectin binding patterns showed that Cd caused alteration of SBA and DBA labeling of trophoblast-derived cells, which suggested increased expressions of α and ß GalNAc. Cd also caused decreased UEA-1 binding affinity, which indicated fewer α-L-Fuc residues in placentas of Cd treated dams. The nonreactivity in trophoblast I of the control placentas incubated with Con-A contrasted with the labeling in placentas of experimental dams, which indicated increased expression of terminal α-D-Man, and α-D-Glc residues. We found that Cd altered the reactivity of placenta to several lectins, which indicated modification of the glycotype presented by the fetal component of the placenta. We report that Cd exerts a deleterious effect on the glycosylation pattern of the placenta.

Effect of a single dose of cadmium on pregnant Wistar rats and their offspring.

Cadmium (Cd) is a well-known toxicant targeting many organs, among them placenta. This heavy metal also has embryonary and foetal toxicity. This study was undertaken to analyse the effect of a single Cd dose administered at 4, 7, 10 or 15 days of gestation on the offspring of pregnant rats sacrificed at 20 days of gestation. Cadmium chloride was administered subcutaneously at 10 mg/kg body weight to Wistar pregnant dams; control animals received a proportionate volume of sterile normal saline by the same route. Maternal uteri, livers, kidneys and lungs, and foetuses were examined at necropsy. Samples of maternal organs and whole foetuses were collected for histopathologic examination, determination of Cd levels and staining by the Alizarin red S technique. Results revealed a clear embryotoxic and a teratogenic effect of this heavy metal, the former as a significant increase in the number of resorptions, and the latter as significant decrease of the gestational sac weight, and the size and weight of foetuses of Cd-treated dams as well as induced malformations in skull bones, vertebrae and thoracic, and pelvian limbs. The deleterious effects found were similar to those previously reported for other animal models suggesting a high conservation of the pathogenic mechanisms of Cd. Additionally, many of the addressed aspects showed a slight dependence on the time of administration of the toxic that might be due to the accumulation of the metal in different organs, as we were able to demonstrate by the analysis of its concentration.

A combination of the cytokinesis-block micronucleus cytome assay and centromeric identification for evaluation of the genotoxicity of dicamba.

The purpose of this study was to further investigate the cytotoxic and genotoxic effects of dicamba and Banvel(®) employing the cytokinesis-block micronucleus cytome (CBMN-cyt) assay estimated by the analysis of the nuclear division index (NDI), the frequency of micronucleus (MN), nucleoplasmic bridges (NPBs), and nuclear buds (NBUDs). Besides, for mechanism of MN induction CREST anti-kinetochore antibody analysis was performed. The activities of both compounds were tested within the range of 50-500 µg/ml on Chinese hamster ovary (CHO-K1) cells. Overall, dicamba and Banvel(®) produced a NDI dose-dependent decrease but the response was statistically significant only in cultures treated with Banvel(®) at a 100-500 µg/ml concentration range. A dose-dependent induction of MN was observed after dicamba- and Banvel(®)-treatments within the 50-400 µg/ml and 50-500 µg/ml concentration-ranges, respectively. Induction of NPBs and NBUDs was significantly enhanced by both test compounds. The NPBs/MN ratio values found for dicamba and Banvel(®) were 0.04-0.11 and 0.05-0.18, respectively. Results clearly demonstrated that dicamba and Banvel(®) exerted both cyto- and genotoxic damage on CHO-K1 cells. Furthermore, the CBMN-cyt assay employed confirmed our previous investigations concerning the cellular and DNA damaging capabilities of dicamba and highlights that both clastogenic and aneugenic mechanisms are implicated in the MN induction.

Dicamba-induced genotoxicity in Chinese hamster ovary (CHO) cells is prevented by vitamin E.

In the present study the cytogenetic and genotoxic effect of benzoic herbicide dicamba and its Argentinean commercial formulation banvel (57.71% dicamba) was evaluated and whether this effect is mediated through oxidative damage or not. The protective role of vitamin E was also studied. Sister chromatid exchange (SCE) frequency, cell-cycle progression, and cell viability analyses in CHO cells were used as in vitro end-points. Treatments with the test compounds were performed either during 24h (Protocol A) or 12h (Protocol B) before harvesting. Protocol A showed that vitamin E decreased pesticide SCE induction, corrected the cell-cycle delay and partially protected cell-death only in 500 microg/ml dicamba-treated cultures. A similar trend was found in banvel-treated cultures. Protocol B revealed similar protective role of vitamin E only for dicamba-induced geno- and cytotoxicity. Based on these observations it could be suggested that dicamba injures DNA by delivering reactive oxygen species rather than by another type of mechanism/s. Although banvel mimics the effect observed by dicamba, its formulation contains other xenobiotic/s agents able to induce cellular and DNA damage by a different mechanism/s. Further investigations are needed to acquire a comprehensive knowledge of the possible mechanism/s through dicamba and banvel exert their toxic effects.

Genotoxicity analysis of the phenoxy herbicide dicamba in mammalian cells in vitro.

The cytogenetic effects exerted by the phenoxy herbicide dicamba and one of its commercial formulations banvel (57.71% dicamba) were studied in in vitro whole blood human lymphocyte cultures. The genotoxicity of herbicides was measured by analysis of the frequency of sister chromatid exchanges (SCEs) and cell-cycle progression assays. Both dicamba and banvel activities were tested within 10.0-500.0 microg/ml doses range. Only concentrations of 200.0 microg/ml of dicamba and 500.0 microg/ml of banvel induced a significant increase in SCE frequency over control values. The highest dose of dicamba tested (500.0 microg/ml) resulted in cell culture cytotoxicity. The cell-cycle kinetics was affected by both test compounds since a significant delay in cell-cycle progression and a significant reduction of the proliferative rate index were observed after the treatment with 100.0 and 200.0 microg/ml of dicamba and 200.0 and 500.0 microg/ml of banvel. For both chemicals, a progressive dose-related inhibition of the mitotic activity of cultures was observed. Moreover, only the mitotic activity statistically differed from control values when doses of both chemicals higher than 100.0 microg/ml were employed. On the basis of our results, the herbicide dicamba is a DNA damage agent and should be considered as a potentially hazardous compound to humans.