Cardiovascular system and kidney as specific targets of chronic exposure to vanadate in the rat: functional and morphological findings

The geochemistry of geophagic material consumed in Onangama Village, Northern Namibia: a potential health hazard for pregnant women in the area

Ingestion of geophagic materials might affect human health and induce diseases by different ways. The purpose of this study is to determine the geochemical composition of geophagic material consumed especially by pregnant women in Onangama Village, Northern Namibia and to assess its possible health effects. X-ray fluorescence and inductively coupled plasma mass spectrometry were used in order to determine the major, and trace elements as well as anions concentrations of the consumed material. The geochemical analysis revealed high concentrations of aluminium (Al), calcium (Ca), iron (Fe), magnesium (Mg), manganese (Mn), potassium (K), sodium (Na), and silica (Si); and trace elements including arsenic (As), chromium (Cr), mercury (Hg), nickel (Ni) and vanadium (V) as well as sulphate (SO₄^2-), nitrate (NO₃^-), and nitrite (NO₂^-) anions comparing to the recommended daily allowance for pregnant women. The pH for some of the studied samples is alkaline, which might increase the gastrointestinal tract pH (pH < 2) and cause a decrease in the bioavailability of elements. The calculated health risk index (HRI > 1) revealed that Al and Mn might be a potential risk for human consumption. Based on the results obtained from the geochemical analysis, the consumption of the studied material might present a potential health risk to pregnant women including concomitant detrimental maternal and foetal effects.

Reversal of vanadium-induced toxicity by combination therapy of tiferron and α-tocopherol in rat during pregnancy and their fetuses

OBJECTIVE

The aim of this study was to analyze the effect of tiferron (sodium 4, 5-dihydroxybenzene-1, 3-disulfonate) per se and combination with α-tocopherol against vanadium induced developmental toxicity. Vanadium, as vanadyl sulphate pentahydrate, was evaluated for embryotoxic/fetotoxic effect in female albino rats (Sprague Dawley).

METHODS

The compound was administered by gavage to pregnant animals at a dose of 15 mg/kg/day, p.o. on day 6-15 of pregnancy (organogenesis). Tiferron was given on day 16-18 as chelating agent. Cesarean sections were performed on day 19 of gestation.

RESULTS

Maternal toxicity was observed, the level of sugar in the blood decreased, while we observed an increase in serum protein, serum alkaline phosphatase and serum transaminase activity. Level of lipid peroxidation showed enhances value in fetal and maternal liver. Vanadium induced inhibition in glycogen contents. Protein contents were decreased in vital organs where as increased in uterus and placenta. There was increased activity of acid phosphatase with the concomitant decline in alkaline phosphatase, adenosine triphosphatase and succnic dehydrogenase after vanadium intoxication. Toxicant caused severe alteration in histopathological observation of maternal and fetal liver, kidney, uterus and placenta proving its toxic consequences at cellular level. Tiferron along with α-tocopherol dramatically reversed alterations of all variables towards control rather than individual treatment.

CONCLUSION

The combination therapy of tiferron and α-tocopherol played a beneficial role in reducing vanadium induced developmental toxicity.

Vanadate as factor of cardiovascular regulation by interactions with the catecholamine and nitric oxide systems

The effects of 1 microgram/mL of vanadium, given for 12 mo as sodium metavanadate in drinking water, on cardiovascular and biochemical indices of male rabbits were investigated. At the end of the exposure period, vanadium was more accumulated in bones and kidneys than in spleen and liver; the cardiac ventricles and the aorta contained similar amounts of this element. Blood pressure and heart rate were unchanged in the vanadate-exposed animals since the observed decrease of both cardiac inotropism and stroke volume was counteracted by an increase of peripheral vascular resistance, with reduction of arterial blood flow. The arterial levels of sodium, potassium and aldosterone were unmodified by vanadate which, however, strongly raised those of noradrenaline, adrenaline, L-DOPA, and dopamine. Vanadate caused a marked increase of the activity of monoamine oxidase in renal tubules and liver (probably in relation to the increased plasma catecholamine levels) and a reduction of that of glucose-6-phosphate dehydrogenase in the kidney. There was also evidence that vanadium reduces synthesis and/or release of nitric oxide, the endothelium-derived vasodilating factor, likely through a reduced formation from bradykinin. It was concluded that vanadium may represent an environmental factor of altered cardiovascular homeostasis.

Effects of maternal vanadate treatment of fetal development

Oral vanadate treatment is effective in normalizing blood glucose in both Type I and Type II diabetics. Using Sprague Dawley rats we examined the effectiveness of such treatment in amelioration of hyperglycemia in diabetic pregnancy and its effect on fetal growth in both normal and diabetic pregnant dams. Initiation of vanadate treatment to diabetic and normal pregnant dams increased blood vanadium levels in both groups, but this concentration in the diabetic pregnant group reached approximately twice the value present in the normal group. Despite this high blood vanadium level in the diabetic pregnant dams, oral vanadate treatment was not effective in normalizing blood sugar in this group. Additionally, vanadate treatment was found to be toxic during diabetic pregnancy, causing death to 45% of the test animals. Maternal blood vanadium had a negative effect on fetal development, markedly reducing the number of live fetuses per pregnancy. In summary, oral vanadate treatment is toxic and ineffective during diabetic pregnancies and interferes with fetal growth and development in both normal and diabetic pregnancy.