Changes in Sensitivity to the Effects of Atrazine on the Luteinizing Hormone Surge in Female Sprague-Dawley Rats after Repeated Daily Doses: Correlation with Liver Enzyme Expression
| Autor: | Robert L. Sielken, Chad D. Foradori, Robert J. Handa, James W. Simpkins, Charles B. Breckenridge, Pragati S. Coder |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
Phase II metabolism Embryology medicine.medical_specialty Health Toxicology and Mutagenesis Area under the curve Toxicology 03 medical and health sciences chemistry.chemical_compound 030104 developmental biology 0302 clinical medicine Endocrinology chemistry Pharmacokinetics Internal medicine Liver enzyme Pediatrics Perinatology and Child Health medicine Sprague dawley rats Atrazine Luteinizing hormone 030217 neurology & neurosurgery Drug metabolism Developmental Biology |
| Zdroj: | Birth Defects Research. 110:246-258 |
| ISSN: | 2472-1727 |
| Popis: | Background Atrazine suppression of the LH surge slowly develops over time and peaks after 4 days; sensitivity to atrazine decreases after 8 or 14 days of dosing. Adaptation of the LH response was correlated with increased phase I and phase II liver enzyme activity/expression. Methods The effect of atrazine on the LH surge was evaluated in female Sprague-Dawley rats administered 100 mg/kg/day atrazine by gavage for 1, 2, 3, or 4 consecutive days or 6.5, 50, or 100 mg/kg/day atrazine for 4, 8, or 14 days. Results No statistically significant effects of atrazine were seen on peak plasma LH or LH area under the curve (AUC) after one, two, or three doses of 100 mg/kg/day. Four daily doses of 50 or 100 mg/kg atrazine significantly reduced peak LH and LH AUCs, whereas 6.5 mg/kg/day had no effect. After 8 or 14 days of treatment, statistically significantly reduced peak LH and LH AUC were observed in the 100 mg/kg/day dose group, but not in the 6.5 or 50 mg/kg/day dose groups, although significantly reduced LH was observed in one sample 9 hr after lights-on in the 50 mg/kg/day dose group on day 14. The number of days of treatment required to achieve a significant suppression of the LH surge is consistent with the repeat-dose pharmacokinetics of the chlorotriazines. Conclusion The apparent adaptation to the effect of atrazine on the LH surge after 8 or 14 days may be related to the induction of phase I or, more likely, phase II metabolism observed in this study after 8 days, or to a decreased sensitivity of the hypothalamic-pituitary-adrenal axis or an homeostatic adaption of the effect of atrazine on the LH surge mechanism. Birth Defects Research, 2017. © 2017 The Authors. Birth Defects Research Published by Wiley Periodicals, Inc. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text