Gas chromatographic determination of inorganic tin in rat urine after a single oral administration of stannous chloride and mono-, di-, and triphenyltin chloride

Fecal transplantation of young mouse donors effectively improves enterotoxicity in elderly recipients exposed to triphenyltin

Triphenyltin (TPT) is a widely used biocide known for its high toxicity to various organisms, including humans, and its potential contribution to environmental pollution. The aging process leads to progressive deterioration of physiological functions in the elderly, making them more susceptible to the toxic effects of environmental pollutants. This study aimed to investigate the mitigating effect of fecal transplantation in young mice on the toxicological impairment caused by TPT exposure. For the study, 18-month-old mice were divided into four groups with six replicates each. The control group was fed a basal diet, the TPT group was exposed to 3.75 mg/Kg TPT, the feces group received fecal transplantation from 8-week-old young mice, and the combined group was exposed to 3.75 mg/Kg TPT after receiving fecal transplantation. Compared with the elderly control group, TPT induced significant upregulation of mRNA expression of pro-inflammatory factors (IL-1β, IL-6, TNF-α), while the anti-inflammatory factor gene IL-10 was significantly suppressed. The mRNA expression of intestinal barrier proteins (Claudin, Occludin, Muc2) was also significantly downregulated. However, fecal transplantation in young mice alleviated TPT-induced changes in inflammatory factors, ameliorated oxidative stress, and increased the activities of antioxidant enzymes (including SOD, CAT, GSH-Px). Further analysis using 16 s RNA showed that exposure to TPT led to changes in the composition of the intestinal flora. Untargeted metabolomics observations of feces from older mice revealed that exposure to TPT resulted in altered fecal metabolites. Fecal transplantation in young mice altered the microbiota of TPT-exposed older mice, especially by enhancing the levels of core probiotics. Similar beneficial effects were observed through untargeted metabolomics. Overall, this study highlights the potential benefits of young fecal transplantation in protecting the elderly from the toxicity of TPT, offering a promising approach to improve healthy aging.

Acute toxic effects of dioctyltin on immune system of rats

In the present study, dioctyltin chloride (DOTC: 100mg/kg, BW) was orally administered to immature (30-day-old) male rats, and the acute toxic effects were studied. Di- and monooctyltin (its metabolite) accumulations were mainly detected in the liver, and peaked 48h later. A similar pattern was also found in the kidney, but the levels were low or trace amounts. Significantly low thymus and spleen weights were detected in DOTC-treated animals. Increased apoptotic cell numbers in the thymus and spleen were observed in DOTC-treated animals also. Although the expression of 97 genes involved in apoptosis was studied in the thymus, at least 24h after treatment, we could not detect clearly different expressions between DOTC- and vehicle-treated animals. The present results suggest that DOTC was selectively immunotoxic. One of the mechanisms for its immunotoxicity would be via its stimulation of immune cell apoptosis.

Metabolism of tributyltin and triphenyltin by rat, hamster and human hepatic microsomes

Tributyltin and triphenyltin are metabolized by cytochrome P-450 system enzymes, and their metabolic fate may contribute to the toxicity of the chemicals. In the current study, the in vitro metabolism of tributyltin and triphenyltin by rat, hamster and human hepatic microsomes was investigated to elucidate the metabolic competence for these compounds in humans. The metabolic reaction using microsome-NADPH system that is usually conducted was not applicable to in vitro metabolism of organotins, especially triphenyltin. We therefore examined the effects of dithiothreitol (DTT), one of the antioxidants for sulfhydryl groups, to determine the in vitro metabolism of tributyltin and triphenyltin. As a result, the treatment with 0.1 mM DTT in vitro increased the activity of the microsomal monooxygenase system for metabolism of tributyltin as well as triphenyltin; the total yield of tributyltin and triphenyltin metabolites as tin increased, respectively, by approximately 1.8 and 8.9 times for rat, 2.1 and 1.2 times for hamster, and 1.6 and 1.5 times for human. It is suggested that the organotins directly inactivate cytochrome P-450 because of the interaction with critical sulfhydryl groups of the hemoprotein. We confirmed the utility of this in vitro metabolic system using DTT in the hepatic microsomes of phenobarbital (PB)-pretreated and untreated hamsters. Thus, the in vitro metabolic system described here was applied to a comparative study of the metabolism of organotins in rats, hamsters and humans. Tributyltin was metabolized more readily than triphenyltin in all the species. In humans, the in vitro metabolic pattern resembled that of hamsters, which were susceptible to in vivo triphenyltin toxicity because of incompetent metabolism. It is possible that the hamster is a qualitatively and quantitatively suitable animal model for exploring the influence of tributyltin and triphenyltin in humans.

Metabolism of a tetraphenyltin compound in rats after a single oral dose

The metabolism of tetraphenyltin in rat liver and kidney has been examined. Tetraphenyltin and its metabolites in the tissue were determined periodically for 96 h after a single oral dose of 55.4 mg kg(-1) of tetraphenyltin by gas chromatography. The gas chromatographic method was able to determine simultaneously both inorganic tin and phenyltin compounds. Although initial (at 24 h) levels of tetraphenyltin in the liver approximated four times those in the kidneys, the levels of tetraphenyltin decreased more rapidly with time than those in the kidneys. These findings show that the tetraphenyltin accumulated more rapidly and highly in the liver, but was metabolized faster than that in the kidney. The levels of total tin in the liver 24 h after treatment were distinctly lower than those of di- or triphenyltin treatments in our previous studies and none of the animals showed characteristic symptoms. The toxic potencies of organotins generally correlate with accumulation of the chemicals. These results imply that the slight toxicities of tetraphenyltin might be due to the relatively low uptake of tin compounds after ingestion. The highest tin concentration among the metabolites of tetraphenyltin in the tissue, especially in liver, was observed as diphenyltin throughout the time period studied. These results suggest that part of the administered tetraphenyltin may cause some harmful effects as diphenyltin in rats, and this must be taken into consideration in toxicological research on tetraphenyltin.

Suppression of uterine decidualization correlated with reduction in serum progesterone levels as a cause of preimplantation embryonic loss induced by diphenyltin in rats

In our previous study, diphenyltin dichloride (DPTCl) at 16.5 mg/kg and higher on days 0-3 of pregnancy was found to induce preimplantation embryonic loss in rats. In the present study, the effects of DPTCl on uterine decidualization in pseudopregnant rats, effects of ovarian hormones on uterine decidualization in ovariectomized rats, and effects of progesterone on the DPTCl-induced preimplantation embryonic loss in pregnant rats were determined. Female rats were given DPTCl by gastric intubation at 4.1, 8.3, 16.5, or 24.8 mg/kg on days 0-3 of pseudopregnancy and the decidual cell response was induced on day 4 of pseudopregnancy. The uterine weight on day 9 of pseudopregnancy served as an index of uterine decidualization. A significant decrease in uterine weight, which indicates suppression of uterine decidualization, was detected at 16.5 and 24.8 mg/kg. Ovarian weight and number of corpora lutea in the DPTCl-treated groups were comparable to the controls. A significant decrease in the serum progesterone levels was found at 16.5 and 24.8 mg/kg in pseudopregnant rats. The hormonal regimen consisting of progesterone and estrone-supported decidual development in ovariectomized rats given DPTCl. Pregnancy rate and number of implantations were significantly lower in the intact mated groups given DPTCl at 16.5 and 24.8 mg/kg on days 0-3 of pregnancy than in the control group and significantly higher in the groups given DPTCl plus progesterone than in the groups given DPTCl alone. These results show that reduction in serum progesterone levels is correlated with suppression of uterine decidualization and progesterone protects against preimplantation embryonic loss induced by DPTCl.

Effects of pretreatment with SKF-525A on triphenyltin metabolism and toxicity in mice

The effects of cytochrome P-450 inhibition by alpha-phenyl-alpha-propylbenzeneacetic acid 2-[diethylamino]-ethyl ester hydrochloride (SKF-525A), which inhibits the activity of a number of cytochrome P-450s, on triphenyltin metabolism and toxicity in mice were studied. At 24 h after triphenyltin administration, the triphenyltin levels in the tissues of SKF-525A-pretreated mice were about three times of those in the tissues of SKF-525A-untreated mice and the ratio of metabolites to parent triphenyltin in the tissues of SKF-525A-pretreated mice was lower than those in the tissues of SKF-525A-untreated mice. These data indicate that the pretreatment of SKF-525A decelerated the triphenyltin metabolism and increased triphenyltin accumulation in the tissues of mice. Although triphenyltin did not affect plasma glucose levels of in the SKF-525A-untreated mice, the triphenyltin produced marked hyperglycemia in SKF-525A-pretreated mice. These results suggest that the inhibition of cytochrome P-450 system enzymes by SKF-525A affects the metabolism and toxicity of triphenyltin and has a key role in inducing the hyperglycemic action of triphenyltin, i.e. by increasing triphenyltin accumulation in the mice.

Comparative study of the metabolism of triphenyltin in hamsters and rats after a single oral treatment with triphenyltin chloride

Our previous work has shown that triphenyltin compound induces the diabetogenic effects, such as hyperglycemia and hypertriglyceridemia, on hamsters, but not on rats. In the present study, it is examined whether the species differences in the metabolic fate of triphenyltin exist for susceptibility between hamsters and rats. Triphenyltin chloride was orally dosed to hamsters and rats, and triphenyltin and its metabolites, mono- and diphenyltin, and inorganic tin, in liver, kidney, pancreas, brain, and blood were determined by gas chromatography periodically for 96 h after the treatment. Triphenyltin levels in the tissues of both species were almost maxima within 24 h after treatment. Although there were relatively high levels of triphenyltin in the tissues of hamsters dosed with triphenyltin chloride, compared with those in the rats, the proportion of metabolites to triphenyltin were lower than those in the rats. In particular, hamsters were more susceptible than rats to the pancreatic accumulations of triphenyltin and good correlation exists between the tin concentrations in the pancreas and the plasma glucose levels in triphenyltin-treated hamsters. These findings suggest that the dearylation of absorbed triphenyltin in hamsters is slower than that in rats and that triphenyltin-induced hyperglycemic action depends upon the amount of tin compounds absorbed into the pancreas. Furthermore, most of the tin compounds in the brains of both species were triphenyltin. This result shows that the metabolism of triphenyltin in the brains of both species was different from that in other tissues.