Effects of 1,25-dihydroxicolecalciferol and dietary calcium-phosphate on distribution of lead to tissues during growth
Journal Article
·
· Toxicology and Applied Pharmacology
- Department of Biochemistry, Centro de Investigacion y de Estudios Avanzados del IPN, PO Box 14-740, Mexico City 07000 (Mexico)
The susceptibility to the toxic effects of lead (Pb) is mainly mediated by age and nutritional and hormonal status, and children are among the most vulnerable to them. During growth, an increase in calcium, phosphate and vitamin D in diet is recommended to enhance calcium and phosphate intestinal absorption and bone deposit. Calcium and phosphate reduce lead intestinal absorption, and 1,25-dihydroxicolecalciferol (1,25(OH){sub 2}D{sub 3}) (active metabolite of vitamin D) increases both lead and calcium intestinal absorption. However, the effects of 1,25(OH){sub 2}D{sub 3} on lead bone deposit and redistribution to soft tissues are not well known. In this study, we examined the effects of calcium-phosphate diet supplementation and the administration of 1,25(OH){sub 2}D{sub 3} on Pb distribution to soft tissue and bone in growing rats exposed to Pb. Rats (21 days old) were exposed for 28 days to 100 ppm of Pb solution in drinking water. Calcium and phosphate in diet were increased from 1 to 2.5% and from 0.65 to 1.8%, respectively, and 1,25(OH){sub 2}D{sub 3} was administrated by intraperitoneal injection of 7.2 ng/kg every 7 days. Between 21 and 49 days, the body weight increased about 5 times. The results showed that high calcium-phosphate diet led to lower Pb concentration in blood and in bone, but Pb liver and kidney concentrations increased, which indicates that absorption and bone deposit redistribution of Pb decreased. On the other hand, no effect of this diet rich in calcium-phosphate in Pb concentration was observed in brain. Blood and bone Pb concentrations increased even more when the high calcium-phosphate diet included 1,25(OH){sub 2}D{sub 3}. In the rats treated only with 1,25(OH){sub 2}D{sub 3}, blood and bone Pb concentrations were lower. Higher concentrations of lead in the soft organs were observed also in rats treated under a high calcium-phosphate diet plus 1,25(OH){sub 2}D{sub 3} administration. The above mentioned results suggested that 1,25(OH){sub 2}D{sub 3} induces an increased absorption and redistribution of Pb, and therefore, it may enhance systemic damage in Pb-exposed growing animals.
- OSTI ID:
- 20783409
- Journal Information:
- Toxicology and Applied Pharmacology, Journal Name: Toxicology and Applied Pharmacology Journal Issue: 1-2 Vol. 210; ISSN TXAPA9; ISSN 0041-008X
- Country of Publication:
- United States
- Language:
- English
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