Trace metals and metalloenzymes in placenta after oral administration of lead acetate

Natural antioxidants protect against lead-induced damage during pregnancy and lactation in rat's pups

The aim of this study was to add further evidence to the biochemical changes produced in lead-exposed pups and to investigate the potential role of natural antioxidants against the lead-induced damage. Pregnant Wistar rats received treatments with drinking water, divided into four groups, as follows: (1) distilled water; (2) lead (300mg/L); (3) lead+Zn (20mg/L)+vitamins A (50,000U/L), C (2g/L), E (500mg/L) and B(6) (500mg/L); and (4) vitamins+Zn solution. We found a significant decrease in haemoglobin and haematocrit values as well and an increase in haemolysis among lead-exposed pups. Vitamins and zinc supplementation were effective in restoring delta-aminolevulinic acid dehydratase, inhibited by lead in erythrocytes, but did not reach control values. Lead exposure increased the production of thiobarbituric acid reactive substances (TBARS) and catalase activity in kidneys and liver that were reduced by the co-administration of vitamins and zinc. Our findings suggest that administration of antioxidants during gestation and lactation could prevent some of the negative effects of lead.

Lead intoxication in gestational and lactation periods alters the development of male reproductive organs

The effect of lead (Pb) intoxication during pregnancy and lactation on the male reproductive system was studied to evaluate the alterations caused by Pb in the development of pups. The investigations covered the effect of lead on the course of spermatogenesis and the development of the epididymis and reproductive glands. For this purpose, dams were intoxicated with 300 mg/L Pb during the gestational period and through lactation. Pups were sacrificed on Postnatal (PN) Days 12 and 21. Blood lead (PbB) and plasma iron concentrations were measured, and blood cells counted. Biochemical studies as well as histochemical analyses were performed on testes and accessory glands of the reproductive system. Lead intoxication resulted in a decrease in testis and seminal vesicle weights and an increase in DNA and RNA levels on PN Day 21. Total protein was significantly decreased by the toxicant, and alkaline and acid phosphatase levels of the gonads were reduced. Effects were also reflected in the reduction of the thickness of epithelium and of seminiferous tubule diameter (STD) as a consequence of the action of lead in the reduction in numbers of prospermatogonia and spermatocytes. Results indicate that the reproductive system targets of lead intoxication are not only the testes; lead intoxication results in the inhibition of testicular, epididymal, and seminal vesicle function, altering the biochemical composition of these organs, and consequently, affecting the normal development of germinal cells.

Effect of calcium supplements to a maize-soya diet on the bioavailability of minerals and trace elements and the accumulation of heavy metals in growing rats

Thirty-five (five groups with seven animals each) male albino rats (initial average weight = 44 g) were fed phytate-rich diets (analysed phytic acid concentration = 6.9 g/kg) based on maize and soy bean meal (5 g Ca, 3 g P, 1.2 g Mg, 23 mg Zn, 10 mg Pb, 5 mg Cd/kg diet). Experimental diets were supplemented with 0, 2, 4, 6 and 8 g calcium from CaCO3 per kg. The supplementation of increasing amounts of calcium resulted in a dose-dependent decrease in the apparent absorption of phosphorus. Furthermore, apparent zinc absorption and femur zinc concentration were moderately decreased due to the calcium supplementation. Kidney Cd concentration was significantly lower in rats that were fed the high calcium diets in comparison with the control animals. Femur lead concentration and hepatic delta-aminolevulinic acid dehydratase, which are known to be sensitive parameters of lead accumulation remained unchanged by the different dietary treatments. Magnesium absorption as well as liver and plasma zinc concentration and activity of plasma alkaline phosphatase were also unaffected. Although calcium supplementation may lead to a decrease in the accumulation of certain heavy metals such as cadmium, the carry-over of lead was not affected under the given experimental conditions. Furthermore, calcium-phytate-zinc interactions may adversely affect zinc bioavailability in growing rats.

State of pregnancy modifies lead toxicity in mice

Toxicity of lead acetate after administration through the oral route at 0-50 mg/kg body weight of animal has been assessed in the liver of pregnant mice and compared with the effect in the liver of nonpregnant dams. Analysis showed that the basal level of hepatic lead is considerably reduced during pregnancy as compared to that in nonpregnant state. After administration of Pb-acetate, deposited lead in liver of nonpregnant mice was 3- to 4-fold while in pregnant mice was, it was 1.8- to 3.0-fold over their respective control values. Although hepatic Fe, Cu, and Zn levels had a tendency to be lowered during pregnancy, it appeared that the added trace quantity of lead prior to and during pregnancy helped in the retention of these metals, which either remained unaffected (as Fe) or declined (Cu and Zn) after lead administration during the nonpregnant state. The effect of lead on Mn diminution, however, was visible at the dose of 50 mg/kg body wt of lead-acetate. Alkaline phosphatase, which increased during pregnancy along with Mn, was reversed between the pregnant and nonpregnant states after oral administration of lead. On the other hand, the level of delta-aminolevolunic acid dehydratase, which declined during normal pregnancy, continued to fall further after lead exposure. It is concluded that the distribution of basal or administered lead and its effect on enzyme activities and trace metal composition in liver depends on the pregnant and nonpregnant states of female hosts.