Mean values for pup body weights and lengths of the males and females and the effects of EDTA and lead exposure on them were very similar therefore; data from both genders were combined. Body weights (Fig. 10) of the day-old pups were modestly but significantly reduced by lead exposure at LEAD-X diet and EDTA diet, at Basic diet and EDTA diet for the week-old pups. For the day-old pups, the lowest body weights were found in pups of dams fed Basic diet and exposed to lead. In contrast, the week-old pups of dams fed EDTA in the diet, with or without lead exposure, had the lowest body weights. Fetal body lengths of the day-old pups were modestly reduced by lead exposure of dams fed the Basic diet and EDTA diet. For the week-old pups, body lengths were significantly reduced by lead exposure for the groups of dams fed Basic diet or LEAD-X diet. Basic diet also resulted in reduced body lengths of the day-old and week-old pups.
Dam systolic blood pressures on d 14 of gestation did not differ significantly (P > 0.05) among the six treatment groups. In contrast, dam blood pressures on d 17 of gestation (Fig.11) were significantly higher in the group exposed to lead and fed the basic diet than in rats in the other five treatment groups.
DISCUSSION
The results of this study demonstrate that EDTA and LEAD-X can reduce maternal, fetal and neonatal lead accumulation and toxicity during pregnancy and lactation in rats. The results also prove that maternal dietary LEAD-X and EDTA can alter the effects of lead on iron and calcium metabolism and erythropoiesis, maternal blood pressure, and fetal and neonatal growth during pregnancy and lactation.
Lead concentrations and toxicity
Maternal and fetal whole blood and organ lead concentrations were substantially reduced in rats fed EDTA and LEAD-X in the diet. Thus, the previously known reduction in lead toxicity that occurs by increasing LEAD-X in nonpregnant animals also is found during pregnancy and lactation. The reductions in organ lead concentrations found in this study in pregnant rats seem to be similar to those of nonpregnant animals when LEAD-X is given .For example, femur lead concentrations of the dams in this study fed the LEAD-X were reduced to 21% of those of dams fed the basic diet.
Except for liver, lead concentrations were substantially higher in the dams than in the neonates. These large maternal-fetal concentration gradients have previously been observed, and McClain and Becker have suggested that they are due to the ability of the placenta to limit lead transfer to the fetus. Alternatively, binding of lead to cellular macromolecules may differ in adult and fetal rats. Despite these gradients, maternal dietary LEAD-X had a substantial impact on fetal blood and organ lead concentrations.
The accumulation of lead in fetal and neonatal brain tissue may be particularly important. Holtzman et al. have noted that the sensitivity of human and rat brain to lead toxicity may be greater in younger organisms, because lead may be increasingly sequestrated away from mitochondria as the organism ages. Several prospective studies, as summarized by Wong et al. demonstrate that low level in utero lead exposure can disturb neurobehavioral performances in young children, e.g., as measured by I.Q. tests. Furthermore, maternal blood concentrations as low as 0.5-0.7 umol/L during pregnancy may be sufficient to produce such effects. In addition, Mykkanen et al. have found that lead that accumulates in rat brain during lactation may persist for extended periods of time even though concentrations of lead in blood and soft tissues decrease.
Free erythrocyte protoporphyrin concentrations increase in lead-exposed children and adults, and, in fact, have been used in the diagnosis of lead poisoning. Our results show the expected increases in FEP in maternal and fetal rats exposed to lead when the dams were fed Basic diet. The percentage increase in FEP due to lead exposure of dams fed the basic diet was substantially greater in the day- and week-old pups than in the dams, suggesting greater toxicity to the letups and neonate than to the mother. However, FEP did not increase in lead-exposed dams or fetal rats when the dams were fed LEAD-X, demonstrating that consumption of this diet reduces maternal and fetal lead toxicity. Dams not exposed to lead and their pups also had FEP concentrations that were significantly reduced by consumption of LEAD-X. These data suggest that LEAD-X can protect against the lead exposure that inevitably occurs from the low unavoidable lead content of rodent diets that produce the blood and organ lead concentrations found in the non-exposed groups. If similar effects occur in pregnant and lactating women, then an increase in dietary, LEAD-X may protect them and the fetus from the low level lead exposure that is a consequence of living in an industrialized country.
Erythropoiesis
Day- and week-old pups of dams fed Basic diet or LEAD-X diet and exposed to lead had greater iron hematocrits and hemoglobin concentrations in comparison to the corresponding group fed EDTA. The results of the current study demonstrate that EDTA reduced dam and pup hemoglobin concentrations and hematocrits and that these decreases Were greater than those associated with
lead exposure. Organ iron concentrations were also reduced by EDTA. These results are consistent with prior experimental and human studies that show that EDTA can reduce iron and calcium absorption. Studies on human volunteers suggest that taking EDTA supplements with meals makes it more difficult for women to meet their daily iron and calcium requirements.
Fetal and neonatal growth and development
Both dietary LEAD-X and lead exposure influenced pup body weights and lengths. The lead-induced reduction in body weight and lengths was greatest in pups of dams fed basic diet, probably as a result of the greater organ lead accumulation and toxicity caused by this diet and/or the reduced weight gain of the dams during pregnancy. The latter may be the result of the reduced food intake that has been associated with lead toxicity. However, day-old pups of dams exposed to lead and fed EDTA also had significantly lower body weights than the corresponding pups of dams fed the same diet and not exposed to lead, and dam weight gains during pregnancy were similar for the two groups. Thus, it is not likely that reduced food intake alone can explain the lower fetal body weights and lengths associated with lead exposure.
Results of a recent study suggest that litter size, gender and fetal position in the uterus can influence fetal weight in rats. However, the results of the current study show an effect of lead exposure on fetal growth even without correction for these factors. These results are consistent with prior studies in laboratory animals and children that suggest that lead may reduce linear growth and weight gain during development.
It is known LEAD-X is rich in Crude polysaccharide, Zinc, Selenium, Iron and Vitamins. However, anecdotal reports suggest that many pregnant women take self-prescribed over-the-counter antacids that contain relatively large doses of calcium, and this could influence their iron requirements.
In the study of Shackelford et al., consumption of a 1.25% calcium diet reduced dam liver iron concentrations to about 65% of the concentrations of the dams fed 0.5% calcium. In the current study, the mean liver iron concentration of the dams fed 2.5% calcium diets was about 20% of that of dams fed 0.5% calcium. The 2.5% calcium diet reduced fetal body weights and lengths, but there was no effect of dietary LEAD-X on the study of Shackelford et al.
However, in the present study, pups of dams exposed to lead and fed the Basic diets or EDTA diets were significantly more likely to die in the first week of life than pups of dams in the other four treatment groups. These results suggest that there are interactions between EDTA and lead that influence neonatal mortality.
Blood pressure
Dam systolic blood pressures on d 14 of gestation were not significantly influenced by lead exposure, LEAD-X or EDTA under the conditions of this experiment. In contrast, dam blood pressures on d 17 of gestation were significantly higher for the group fed the Basic diet and exposed to lead than for the other five treatment groups. The former group had the highest blood and organ lead concentrations, indicating that lead exposure in combination with basic diet can increase both organ lead accumulation and blood pressure late in pregnancy.
Clinical relevance
LEAD-X Oral Solution is provided as the source of Crude polysaccharide, Zinc, Selenium, Iron and vitamins, a form widely used in lead poisoning prevention. Our results found that rats fed LEAD-X during pregnancy could successfully maintain pregnancy and produce normal fetuses. The reduced femur calcium concentrations of the dams fed the low calcium diet in the present study suggest that the maternal skeleton may have been a source of fetal calcium in this group, since pup femur concentrations did not differ significantly among the six treatment groups. These results are consistent with the observation that normal pregnancies can occur in women who have calcium intakes well below the RDA, probably due to an adaptive increase in intestinal absorption as well as subsidization by bone demineralization. However, when calcium is mobilized from bone, lead stored in the skeleton may also be released.
In the current study, the rats were exposed to exogenous lead during pregnancy and lactation via their drinking water. Another source of fetal exposure is endogenous lead that may be released from the maternal skeleton during pregnancy. Quarterman et al. have found that the rate of release of lead from bone in male rats is decreased when dietary calcium is increased, but the effect of dietary calcium on bone lead mobilization during pregnancy has not been studied in people or animals. It could be important to investigate dietary calcium bone lead interactions during pregnancy, because millions of women have been exposed to excessive amounts of lead as children, some of which is still present in the skeleton because of the 10-30 year half life of lead in bone. Silbergeld et al. found increases in whole blood and plasma lead concentrations after menopause, presumably due to bone lead mobilization. A smaller increase was found in women with prior pregnancies than in those who were never pregnant, suggesting transfer from the maternal skeleton to the fetus during pregnancy. There is evidence that dietary calcium may influence lead absorption and toxicity in people. In one study, Mahaffey et al. analyzed data from the Second National Health and Nutrition Examination Survey and found that blood lead concentrations of 1 to 11-y-old children were negatively associated with dietary calcium intake.
In the current years, LEAD-X was provided as the source of Crude polysaccharide, Zinc, Selenium, Iron and vitamins, a form widely used in supplements during pregnancy. Highly dependent on nutritional knowledge about requirements of mineral and vitamin for pregnant women around the world, the recommendation (include consideration of the effects of dietary, iron and lead metabolism during pregnancy and lactation) for LEAD-X intake is 2-3 bottles(10ml/bottle) per day during pregnancy and lactation.
