| Autor: |
Domoradzki, J. Y., Thornton, C. M., Pottenger, L. H., Hansen, S. C., Card, T. L., Markham, D. A., Dryzga, M. D., Shiotsuka, R. N., Waechter, J. M. |
| Předmět: |
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| Zdroj: |
Toxicological Sciences; Feb2004, Vol. 77 Issue 2, p230-242, 13p |
| Abstrakt: |
Previous studies demonstrated the rapid clearance of bisphenol A (BPA) from blood following oral administration to adult rats with the principal metabolite being BPA-monoglucuronide (BPA-glucuronide). Since the ontogeny of glucuronyl transferases (GT) differs with age, the pharmacokinetics of BPA were studied in neonatal animals. 14C-BPA was administered via gavage at 1 or 10 mg/kg body weight to rats at postnatal day (pnd) 4, pnd 7, pnd 21, or to 11 week old adult rats (10 mg/kg dose only). Blood (neonates and adults) and selected tissues (neonates) were collected at 0.25, 0.75, 1.5, 3, 6, 12, 18, and 24 h postdosing. BPA and BPA-glucuronide in the plasma were quantified by high-performance liquid chromatography; radioactivity in the plasma and tissues was quantified by liquid scintillation spectrometry. The data indicate that neonatal rats at all three ages metabolized BPA to BPA-glucuronide, although an age dependency in the number and concentration of plasma metabolites was observed, consistent with the ontogeny of GT. BPA-glucuronide and BPA concentrations in the plasma were greater in neonates than in adults, except at 24 h postdosing, suggesting an immaturity in the development of hepatic excretory function in neonatal rats. Nevertheless, the half-lives for the elimination of BPA-glucuronide in plasma were more rapid in neonatal animals than in adults, likely due to reduced microflora β-glucuronidase activity and an absence of enterohepatic recirculation. A dose dependency in the metabolism and pharmacokinetics of BPA administered to neonates was also observed with nearly complete metabolism of BPA to BPA-glucuronide (94–100% of the plasma radioactivity) at a dose of 1 mg/kg. This was in contrast to finding up to 13 different plasma metabolites observed at the 10 mg/kg dose. These data indicate that, from early in neonatal life through pnd 21, there is sufficient GT activity in rats to efficiently metabolize BPA to its nonestrogenic metabolite at low doses. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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