Embryotoxic and teratogenic effects of intraperitoneally administered metavanadate in mice

Vanadium(IV) oxide affects embryonic development in mice

Vanadium(V) and vanadium(IV) are the predominant redox forms present in the environment, and epidemiological studies have reported that prenatal vanadium exposure is associated with restricted fetal growth and adverse birth outcomes. However, data about the toxic effects of vanadium(IV) oxide (V₂ O₄ ) on the development of mammals are still limited. Therefore, in this work, 4.7, 9.4, or 18.7 mg/kg body weight/injection/day V₂ O₄ was administered through an intraperitoneal (ip) injection to pregnant mice from gestational days 6 to 16. The results showed that V₂ O₄ produced maternal and embryo-fetal toxicity and external abnormalities in the offspring, such as malrotated and malpositioned hind limbs, hematomas and head injuries. Moreover, the skeletons of the fetuses presented reduced ossification of the cranial bones, including the frontal and parietal bones, corresponding to head injuries observed in the external assessment of the fetuses. These results demonstrate that administration of V₂ O₄ to pregnant females in the organogenesis period adversely affects embryonic development.

Effects of ammonium metavanadate on fertility and reproductive performance of adult male and female rats

Vanadium is a ubiquitous trace metal present in most plant and animal tissues. Environmental exposure to trivalent and pentavalent inorganic vanadium compounds has been related to impaired different phases of reproduction. Therefore, the effects of a pentavalent inorganic vanadium compound on general reproductive performance and fertility were investigated in male and female rats. Sexually mature male and female rats were exposed to 200 ppm ammonium metavanadate in drinking water. Male rats were exposed for 70 days, while the female rats exposed for 14 days premating, during mating, and throughout the whole length of gestation and lactation periods till weaning. The effects on male sex organ weights and fertility were evaluated at the end of exposure period. However, the effects on female fertility as well as developmental and postnatal effects were evaluated throughout the exposure period. The fertility was significantly reduced in both treated groups, with more pronounced suppressive effects in the male treated group. The number of implantation sites and the number of viable fetuses were significantly reduced in pregnant females of both treated groups. However, the number of resorptions, dead fetuses, and pre- and postimplantation losses were significantly increased. The incidence of resorptions was significantly increased in treated female group compared with untreated female group. The behavioral responses as well as fetal survival and viability indices were decreased in both treated groups during the lactation period. The incidence of these effects was more pronounced in the treated female group. The morphological, visceral, and skeletal anomalies were recorded significantly increased in fetuses of both treated groups, with more pronounced effects on fetuses of treated females. In conclusion, the exposure of adult male and female rats to ammonium metavanadate would cause adverse effects on fertility and reproduction.

Vanadium

Vanadium is a steel-grey, corrosion-resistant metal, which exists in oxidation states ranging from -1 to +5. Metallic vanadium does not occur in nature, and the most common valence states are +3, +4, and +5. The pentavalent form (VO3-) predominates in extracellular body fluids whereas the quadrivalent form (VO+2) is the most common intracellular form. Because of its hardness and its ability to form alloys, vanadium (i.e., ferrovanadium) is a common component of hard steel alloys used in machines and tools. Although most foods contain low concentrations of vanadium (< 1 ng/g), food is the major source of exposure to vanadium for the general population. High air concentrations of vanadium occur in the occupation setting during boiler-cleaning operations as a result of the presence of vanadium oxides in the dust. The lungs absorb soluble vanadium compounds (V2O5) well, but the absorption of vanadium salts from the gastrointestinal tract is poor. The excretion of vanadium by the kidneys is rapid with a biological half-life of 20-40 hours in the urine. Vanadium is probably an essential trace element, but a vanadium-deficiency disease has not been identified in humans. The estimated daily intake of the US population ranges from 10-60 micrograms V. Vanadyl sulfate is a common supplement used to enhance weight training in athletes at doses up to 60 mg/d. In vitro and animal studies indicate that vanadate and other vanadium compounds increase glucose transport activity and improve glucose metabolism. In general, the toxicity of vanadium compounds is low. Pentavalent compounds are the most toxic and the toxicity of vanadium compounds usually increases as the valence increases. Most of the toxic effects of vanadium compounds result from local irritation of the eyes and upper respiratory tract rather than systemic toxicity. The only clearly documented effect of exposure to vanadium dust is upper respiratory tract irritation characterized by rhinitis, wheezing, nasal hemorrhage, conjunctivitis, cough, sore throat, and chest pain. Case studies have described the onset of asthma after heavy exposure to vanadium compounds, but clinical studies to date have not detected an increased prevalence of asthma in workers exposed to vanadium.

Vanadium: a review of the reproductive and developmental toxicity

While the essentiality of vanadium for living organisms has yet to be established with certainty, vanadium has become an increasingly important environmental metal. Moreover, in recent years pharmacological interest in vanadium has also increased because of the hypothetical utilization of oral vanadium as an alternative therapy to parenteral insulin in diabetic patients. Adverse effects of vanadium depend on the circulating levels of this element. Among those effects, it is now well established that vanadate (V+5) and vanadyl (V+4) may be reproductive and developmental toxicants in mammals. Decreased fertility, embryolethality, fetotoxicity, and teratogenicity have been reported to occur in rats, mice, and hamsters following vanadium exposure. The reproductive vanadium toxicity, the maternal and embryo/fetal toxicity of this trace element, the perinatal and postnatal effects of vanadium, as well as the prevention by chelating agents of vanadium-induced developmental toxicity are reviewed here. The developmental effects of vanadium in pregnant diabetic rats are also summarized.

Toxicology of vanadium compounds in diabetic rats: the action of chelating agents on vanadium accumulation

The possible use of vanadium compounds in the treatment of diabetic patients is now being evaluated. However, previously to establish the optimal maximum dose for diabetes therapy, it should be taken into account that vanadium is a highly toxic element to man and animals. The toxic effects of vanadium are here reviewed. The tissue vanadium accumulation, which would mean an additional risk of toxicity following prolonged vanadium administration is also discussed. Recently, it has been shown that coadministration of vanadate and TIRON, an effective chelator in the treatment of vanadium intoxication, reduced the tissue accumulation of this element, decreasing the possibility of toxic side effects derived from chronic vanadium administration without diminishing the hypoglycemic effect of vanadium. However, previously to assess the effectiveness of this treatment in diabetic patients, a critical reevaluation of the antidiabetic action of vanadium and its potential toxicity is clearly needed.

Prevention by chelating agents of metal-induced developmental toxicity

Chelating agents such as calcium disodium ethylenediaminetetraacetate (EDTA), 2,3-dimercaptopropanol (BAL), or D-penicillamine (D-PA) have been widely used for the past 4 decades as antidotes for the treatment of acute and chronic metal poisoning. In recent years, meso-2,3-dimercaptosuccinic acid (DMSA), sodium 2,3-dimercapto-1-propanesulfonate (DMPS) and sodium 4,5-dihydroxybenzene-1,3-disulfonate (Tiron) have also shown to be effective to prevent against toxicity induced by a number of heavy metals. The purpose of the present article was to review the protective activity of various chelating agents against the embryotoxic and teratogenic effects of well-known developmental toxicants (arsenic, cadmium, lead, mercury, uranium, and vanadium). DMSA and DMPS were found to be effective in alleviating arsenate- and arsenite-induced teratogenesis, whereas BAL afforded only some protection against arsenic-induced embryo/fetal toxicity. Also, DMSA, DMPS, and Tiopronin were effective in ameliorating methyl mercury-induced developmental toxicity. Although the embryotoxic and teratogenic effects of vanadate were significantly reduced by Tiron, no significant amelioration of uranium-induced embryotoxicity was observed after treatment with this chelator.

Metal-induced developmental toxicity in mammals: a review

It is well established that certain metals are toxic to embryonic and fetal tissues and can induce teratogenicity in mammals. The main objective of this paper has been to summarize the toxic effects that excesses of certain metals may cause on mammalian development. The reviewed elements have been divided into four groups: (a) metals of greatest toxicological significance (arsenic, cadmium, lead, mercury, and uranium) that are wide-spread in the human environment, (b) essential trace metals (chromium, cobalt, manganese, selenium, and zinc), (c) other metals with evident biological interest (nickel and vanadium), and (d) metals of pharmacological interest (aluminum, gallium, and lithium). A summary of the therapeutic use of chelating agents in the prevention of metal-induced developmental toxicity has also been included. meso-2,3-Dimercaptosuccinic acid (DMSA) and sodium 2,3-dimercaptopropane-1-sulfonate (DMPS) have been reported to be effective in alleviating arsenic- and mercury-induced teratogenesis, whereas sodium 4,5-dihydroxybenzene-1,3-disulfonate (Tiron) would protect against vanadium- and uranium-induced developmental toxicity.

Prevention by Tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate) of vanadate-induced developmental toxicity in mice

Vanadate is embryotoxic and fetotoxic in golden hamsters, mice and rats. Tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate), a chelating agent widely used in analytical chemistry, is an effective antidote in the treatment of oral or parenteral vanadate poisoning. The present study evaluated the effect of administration of Tiron on sodium metavanadate (NaVO3)-induced developmental toxicity in mice. NaVO3 (25 mg/kg, i.p.) was injected on day 12 of gestation, whereas Tiron was injected subcutaneously at 0, 24, 48, and 72 hr after NaVO3 administration. Tiron effectiveness was assessed at dosage levels of 0, 250, 500, and 1,000 mg/kg. Cesarean sections were performed on gestation day 18. All live fetuses were examined for external, internal, and skeletal malformations and variations. Amelioration by Tiron of NaVO3 developmental toxicity was evidenced by a significant decrease in the number of resorbed fetuses, an increase in the mean fetal weight, and a reduction in the incidence of the skeletal variations caused by NaVO3. According to these results, Tiron offers encouragement with regard to its therapeutic potential for pregnant women exposed to vanadate. However, further investigations, including the effect of increasing the time interval between acute vanadate exposure and initiation of Tiron therapy, are required.