Two-generation reproductive toxicity study of tributyltin chloride in female rats

Activation of human polymorphonuclear neutrophils by environmental contaminants

The toxicity of chemicals of environmental concern to the immune system has been primarily evaluated in animals and, to a lesser extent, in humans. In particular, the effects of various pollutants on B-cell, T-cell, natural killer cells, and monocyte-macrophage cells have been the focus of several reports, but polymorphonuclear neutrophils have largely been neglected. Recent data indicate that neutrophils are important targets for such chemicals, suggesting a potential role of these products in the development of the inflammatory process. The bulk of this review will focus on the role of certain environmental pollutants on human neutrophil cell physiology.

Low dose effects of bisphenol A on sexual differentiation of the brain and behavior in rats

There is an endocrinological concern that environmental endocrine disrupters (EEDs) may influence sexual differentiation. Bisphenol A (BPA), one of EEDs, is released from polycarbonate plastics, and has been detected in the human umbilical cord. In this study, we examined the effect of BPA on the sexual differentiation of open-field behavior and the sexually dimorphic nuclei in the brain in the offspring of rats exposed to BPA during the fetal and suckling periods at a dosage below the human tolerable daily intake (TDI) level. In the control group, females were more active in the open field and had a larger locus coeruleus (LC) volume than males. BPA abolished and inverted the sex differences of the open-field behavior and the LC volume, respectively, without affecting the reproductive system. We also compared the effects of estrogenic compounds, diethylstilbestrol (DES) and resveratrol (RVT), to that of BPA because of their structural similarities. DES affected the open-field behavior, LC volume and reproductive system, while RVT affected the LC volume and the reproductive system. These results suggest that the brain is highly sensitive to BPA at a dosage below TDI and that the disrupting effects of BPA on sexual differentiation may vary from those of RVT and DES.

Spermatogenetic Disorders in Adult Rats Exposed to Tributyltin Chloride during Puberty

Adverse effects of tributyltin (TBT) chloride were investigated on the reproductive system in male adult rats as exposed during puberty. Fifty Sprague-Dawley rats at the age of 35 days were assigned to five different groups: negative control receiving vehicle, methyltestosterone (10 mg/kg B.W.), and TBT chloride treatments (5, 10, and 20 mg/kg B.W.). Animals were treated by oral gavage for ten consecutive days and sacrificed at 5 weeks after final treatment. The treatment of TBT chloride at the high dose of 20 mg/kg B.W. significantly decreased homogenization-resistant testicular sperm counts (p<0.05). The TBT chloride treatment at the doses of 10 and 20 mg/kg B.W. also significantly decreased caudal epididymal sperm counts (p<0.01). Some of motion kinematic parameters (motility, mean angular displacement, lateral head displacement, and dance) of sperms retrieved from vasa deference were significantly decreased in rats treated with the TBT chloride at the dose of 20 mg/kg B.W. (p<0.05). These results provide a further evidence that an exposure to TBT chloride during pubertal period in male rats produces spermatogenic disorders characterized by decreasing testicular and epididymal sperm counts and some motion parameters of sperms in the vasa deference.

Thymic atrophy induced by methoxychlor in rat pups

The effect of Methoxychlor (MXC) on the thymus was examined in rat pups that were delivered from dams receiving MXC at a dietary concentration of 0 or 1500 ppm for a period from pregnancy to lactation. The pups of both sexes were euthanized on postnatal days (PNDs) 7, 14, and 21. Histologically, the thymus showed marked depletion of cortical lymphocytes on PND 7 and also had an increase in lymphophagocytosis in the cortical area on PNDs 14 and 21. Morphometrical analysis disclosed that both cortex and medulla of the thymus from treated pups were reduced in size, but the reduction was more evident in the cortex. A significant increase in transferase-mediated dUTP nick end labeling-positive cells was detected in the cortex area, corresponding to the presence of lymphophagocytosis. Flow cytometric analysis revealed a significant decrease in the double positive (CD3(int)CD4(+)CD8(+)) immature cells on PND 21. These results have suggested that MXC may impair maturation of thymic lymphocytes in rat pups, which results in enhancement of apoptosis leading to thymic atrophy during the postnatal period.

Tributyltin induces human neutrophil apoptosis and selective degradation of cytoskeletal proteins by caspases

Tributyltin (TBT) has frequently been used as a pesticide and in biocidal paints for marine vessels, leading to its presence in the environment. Although TBT was recently found to induce apoptosis in different immune cells, by a mechanism that is not fully established, its effect on neutrophils is not known. In this study, it was found that TBT induced apoptosis in human neutrophils as assessed by cytology, flow cytometry, and degradation of the microfilament-associated protein gelsolin. Furthermore, data showed that TBT induced neutrophil apoptosis by a caspase-dependent mechanism, since addition of z-Val-Ala-Asp(MOe)-CH(2)F (z-VAD-FMK) in the culture prevented the effect of TBT. It was also found that the cytoskeletal proteins gelsolin, paxillin, and vimentin, but not vinculin, were degraded by TBT via caspases, as assessed by immunoblotting. Data indicate that gelsolin, paxillin, and vimentin are three caspase substrates involved in both spontaneous and TBT-induced neutrophil apoptosis. Cells were not necrotic as assessed by trypan blue dye exclusion, and this is in agreement with the absence of vinculin degradation. Evidence indicates that TBT-induced fragmentation of cytoskeletal proteins via caspases is a process that is tightly regulated.