Testosterone pretreatment mitigates cadmium toxicity in male C57 mice but not in C3H mice

Repeated oral dose toxicity study of nickel oxide nanoparticles in Wistar rats: a histological and biochemical perspective

Despite the increasing use of nickel oxide (NiO) nanoparticles (NPs), limited information is available on their toxicological effects. Health consequences of 28 days repeated oral exposure to NiO NPs have not been explored thoroughly. Hence, toxicity investigations were performed after 28-day daily exposure in albino Wistar rats with NiO NPs following Organization for Economic Co-operation and Development test guideline 407. Histopathology, biochemical indices including oxidative stress and biodistribution patterns were evaluated to decipher the toxicological impact of NiO NPs. NiO NP characterization by transmission electron microscopy showed an average size of 12.9 (±3.4) nm. Histological studies depicted a prominent impact on the vital organs of the rats. A dose-dependent rise in both aminotransferase enzyme values was recorded in the homogenates of liver and kidney tissues. A significant decrease in superoxide dismutase activity and increase in catalase activity was noted. Further, a dose-dependent decrease in reduced glutathione content was recorded in rats, which suggested generation of reactive oxygen species and oxidative stress. Increase in the malondialdehyde levels was observed with an increase in the dose substantiating the antioxidant enzyme activity profiles. Biodistribution studies indicated maximum accumulation of Ni content in liver followed by kidney. Excretion of Ni was predominantly through feces and a little through renal clearance. Our study indicated that NiO NPs adversely alter the biochemical profile of the rats and cause histological damage. Further investigations are warranted to address the mechanism by which physiological path these NiO NPs exhibit their toxic nature in in vivo.

Perspectives in endocrine toxicity of heavy metals--a review

An attempt has been made to review the endocrine/hormonal implications of a few environmentally significant metals, viz, lead, mercury, cadmium, copper, arsenic and nickel, in man and animals. Special emphasis has been given to the adrenals, thyroid, testis, ovary and pancreas. Toxic metals can cause structural and functional changes in the adrenal glands. Their effects on steroidogenesis have been reviewed. It has been reported that thyroid hormone kinetics are affected by a number of metallic compounds. Occupational exposure to a few of these metals can cause testicular injury and sex hormone disturbances. Protective effects of a few antioxidants on their reproductive toxicity have also been discussed. Information gathered on female reproductive toxicity of heavy metals shows that exposure to these metals can lead to disturbances in reproductive performance in exposed subjects. Certain metals can cause injury to the endocrine pancreas. Exposure to them can cause diabetes mellitus and disturb insulin homeostasis. The need to develop molecular markers of endocrine toxicity of heavy metals has been suggested. Overall information described in this review is expected to be helpful in planning future studies on endocrine toxicity of heavy metals.

Melatonin increases tissue accumulation and toxicity of cadmium in the bank vole (Clethrionomys glareolus)

Recent study has shown that a short photoperiod increases the accumulation and toxicity of cadmium (Cd) in the bank vole as compared to a long photoperiod. Since many of the effects of photoperiod on physiological processes in small mammals are transduced by the pineal gland and its hormone melatonin, in this study the effect of subchronic melatonin injection (7 micromol/kg/day for 6 weeks) on the hepatic, renal and intestinal Cd accumulation in the bank voles raised under a long photoperiod and exposed to dietary Cd (0.9 micromol/g) was examined. Simultaneously, histological examinations of the liver and kidneys, and analyses of metallothionein (MT) and lipid peroxidation were carried out. Melatonin co-treatment brought about a significant increase in the hepatic (61%), renal (79%) and intestinal (77%) Cd concentrations as compared to those in the Cd alone group. However, the concentrations of MT in the liver and kidneys of the Cd + melatonin co-treated bank voles did not differ from those in the Cd alone group. Also, histopathological changes in the liver (infiltration of leukocytes) and kidneys (glomerular swelling and a focal tubular cell degeneration) as well as an increase (2-fold) in the renal lipid peroxidation occurred only in animals from the Cd + melatonin group. These data indicate that (1) subchronic melatonin injection has similar effect on the tissue accumulation and toxicity of Cd to that produced by a short photoperiod and (2) the Cd-induced toxicity in the liver and kidneys of melatonin co-treated bank voles is probably due to increased Cd accumulation and decreased synthesis of MT.

Sex-specific effects of neonatal exposures to low levels of cadmium through maternal milk on development and immune functions of juvenile and adult rats

Cadmium (Cd) is a major environmental contaminant. Although immunotoxic effects have been associated with Cd exposure, the inconsistency of experimental results underlines the need of an experimental approach more closely related to environmental conditions. We investigated the effects of exposing neonatal Sprague-Dawley rats to environmentally relevant doses of Cd through maternal milk. Dams received 10 parts per billion (ppb) or 5 parts per million (ppm) Cd chloride (CdCl2) in drinking water from parturition until the weaning of the pups. Half of the offspring was sampled at weaning time. The remaining juvenile rats received water without addition of Cd until adulthood. Cd accumulation in kidneys of juvenile rats fed from dams exposed to Cd indicated the transfer of the metal from mother to pups through maternal milk. This neonatal exposure resulted in decreased body, kidney and spleen weights of just weaned females but not of males. This effect was more pronounced in the less exposed females fed from dams exposed to 10 ppb Cd, which also displayed lower hepatic metallothionein-1 (MT-1) mRNA levels. The effect of Cd exposure on body and organ weights did not persist to adulthood. In contrast, we observed gender-specific effects of neonatal Cd exposure on the cytotoxic activity of splenic NK-cells of both juvenile and adult rats. Cd also strongly inhibited the proliferative response of Con A-stimulated thymocytes in both male and female adult rats 5 weeks after the cessation of Cd exposure. These immunotoxic effects were observed at doses much lower than those reported to produce similar effects when exposure occurred during adulthood. In conclusion, neonatal exposures to environmentally relevant levels of Cd through maternal milk represent a critical hazard liable to lead to both transitory and persistent immunotoxic effects.

Photoperiod affects hepatic and renal cadmium accumulation, metallothionein induction, and cadmium toxicity in the wild bank vole (Clethrionomys glareolus)

The objective of this study was to examine the toxic effects of dietary cadmium (Cd) on bank voles, being the F1 offspring of a wild-caught population. For 6 weeks, the rodents were provided with diets containing 0.05 (control), 40, 80, and 120 microg Cd/g dry wt of diet under moderate (12 h) and long (16 h) photoperiods. Histological examinations and analyses of metallothionein (MT), Cd, Cd bound and not bound to MT, iron and lipid peroxidation in the liver and kidneys were carried out. Histopathological changes occurred in the liver (infiltrations of leukocytes) and kidneys (hemorrhage, glomerular injury, tubular cell degeneration) of bank voles fed the highest dose of dietary Cd only under the moderate photoperiod. The same voles also exhibited the highest values of hepatic and renal Cd, Cd not bound to MT, and renal lipid peroxidation. It seems that under the long photoperiod the liver and kidneys of bank voles were protected against Cd-induced injury through decreasing Cd accumulation and increasing synthesis of MT.

Cyproterone acetate induces a cellular tolerance to cadmium in rat liver epithelial cells involving reduced cadmium accumulation

Several reports indicate that some steroids, in particular sex steroid hormones, can modify cadmium toxicity. We recently reported that cyproterone acetate (CA), a synthetic steroidal antiandrogen that is closely related in structure to progesterone, affects cadmium toxicity in mice. In the present study, we investigated the effect of CA on cadmium toxicity in a rat liver epithelial cell line (TRL 1215) in vitro. Cells were exposed to various concentrations of CA (0,1,10, or 50 microM) for 24 h and subsequently exposed to cadmium (0,50, or 100 microM; as CdCl2) for an additional 24 h. CA pretreatment resulted in a clear decrease in the sensitivity to cadmium. Additional time course study showed CA pretreatment provided protection against cadmium toxicity but only when given for 6 or more hours prior to cadmium exposure. Cellular cadmium accumulation was markedly reduced (60% decrease) in cells pretreated for 6 or more hours with CA. In the presence of protein synthesis inhibitors the protective effect of CA toward cadmium toxicity was abolished. However, in the presence of the GSH synthesis inhibitor, L-buthionine (S,R)-sulfoximide (BSO), the protective effect of CA toward cadmium toxicity remained. CA alone increased metallothionein (MT) levels 2.4-fold, while cadmium (50 microM) alone resulted in a 8.9-fold increase over control. However, cadmium-induced MT synthesis was markedly decreased by CA pretreatment probably because of reduced cadmium accumulation. Analysis of various metal transporters by bDNA signal amplification assay revealed that the ZnT-1 transporter gene, which encodes for a membrane protein associated with zinc efflux, was expressed three-fold more in CA treated cells than control. These data show that CA pretreatment provides protection against cadmium toxicity in vitro and indicate that this protection is due to a decreased accumulation of cadmium rather than through activation of MT synthesis. This decrease of cellular cadmium accumulation appears to be related to events that require protein synthesis and may be due to activation of the genes associated with zinc efflux.

Differential expression of mRNA coding for the alpha-2-macroglobulin family and the LRP receptor system in C57BL/6J and C3H/HeJ male mice

Expression of mouse A2M (MAM), murinoglobulin (MUG), the A2M receptor or LDL-Receptor related protein (A2MR/LRP) and the Receptor Associated Protein (RAP) were measured by northern blotting of mRNA isolated from liver, heart and peritoneal macrophages from C3H/HeJ and C57BL/6J (B6) mice. Marked differences between males of the two mouse strains were observed for MAM and MUG mRNA levels in liver, which were reflected in plasma levels of both proteinase inhibitors, as confirmed by immune-electrophoresis. C3H/HeJ mice had higher levels of the MAM and MUG mRNA and their corresponding plasma proteins than B6 mice. B6 mice expressed higher levels of LRP mRNA relative to C3H/HeJ mice but had lower levels of RAP mRNA. LRP receptor activity, assayed by fluoresceinated-A2M binding, was higher in B6 cells. The present data contribute to the knowledge of genetic background characteristics among male mouse of these two strains, which can take part in many biological events such as lipid metabolism, inflammation and immune response to different infectious agents.

Caffeine decreases the occurrence of cadmium-induced forelimb ectrodactyly in C57BL/6J mice

BACKGROUND

Cadmium is a well-known animal teratogen. Caffeine is an alkaloid widely consumed by humans. Interactions between teratogens and nonteratogenic doses of other agents are becoming widely studied, as they may shed light on understanding mechanisms of teratogenicity or possible prevention of teratogenic effects.

METHODS

C57BL/6JBK mice were injected intraperitoneally (ip) with cadmium sulfate (Cd) at 0, 1.00 (LDCd), 2.50 (MDCd), or 5.00 (HDCd) mg/kg, immediately followed by subcutaneous (sc) administration of 0 or 50 mg/kg caffeine (CAFF) on gestation day (GD) 9. Fetuses were examined on GD 18 for ectrodactyly and other gross morphological malformations.

RESULTS

Amelioration of cadmium-induced forelimb ectrodactyly by CAFF was seen in both the high-dose cadmium (HDCd = 65.4%, HDCd+CAFF = 39.2%) and medium-dose cadmium (MDCd = 46.2%, MDCd+ CAFF = 20.8%) treatment groups (P < 0.025). Bilateral expression of ectrodactyly was also decreased in the presence of caffeine. A statistically significant reduction in Cd-induced abnormalities, including: eye, abdominal, and other skeletal defects, was not seen with caffeine addition, although they did trend downward in the caffeine-supplemented groups. Litter size, fetal weight, fetal mortality, and dam weight also were not affected by co-treatment with caffeine.

CONCLUSIONS

This study provides evidence that a subteratogenic dose of caffeine can ameliorate cadmium-induced forelimb ectrodactyly in the Cd-sensitive C57BL/6J inbred mouse strain.