PM15 Biomarkers
Exhibit Hall
8:00 AM - Monday
(PM247) Relative Sensitivity of Different Thyroid Variables for Detecting Perchlorate-Induced Alterations in Thyroid Function.
Isanhart, J1, Severt, S1, Smith, P1, 1 Texas Tech University, Lubbock, TX, United States
ABSTRACT- Perchlorate is known to be a competitive inhibitor of iodide uptake into the thyroid gland. At therapeutic doses, the result is reduced secretion of thyroid hormones. One of the most often used indices of perchlorate exposure has been plasma thyroid hormone concentrations, which are highly variable measures of thyroid function. The objective of our study was to determine if thyroid gland thyroxine (T4) content was a more sensitive indicator of thyroid function than plasma thyroid hormone concentrations in two species of perchlorate-exposed rodents. Glandular T4 content may be a more sensitive indicator of perchlorate-induced alterations in thyroid function than plasma thyroid hormone concentrations in adult male prairie voles (Microtus ochrogaster) exposed to perchlorate for 51 days (n=21; 0, 1, and 10 mg/kg/day). There were no significant perchlorate-induced reductions in vole plasma triiodothyronine (T3) or T4 concentrations, however, the 10 mg/kg treatment group had significantly lower mean thyroid gland T4 concentrations than controls. Alternatively, thyroid gland T4 content may not be a more sensitive indicator of thyroid function in deer mice (Peromyscus maniculatus). Analyses of deer mice plasma indicated that there were significant perchlorate-induced reductions in plasma T3 and T4 concentrations among treatment groups; however, there were no significant alterations in thyroid gland T4 concentrations among treatment groups. Adult male and female mice exposed to perchlorate in the food for 21 days (n=6 per group; 0 and 1 mg/kg/day) had significantly lower plasma T3 concentrations as compared to controls. In contrast, there were significant differences in plasma T4 concentrations among treatment groups of adult male and female mice exposed to perchlorate in the water for 21 days (n=6 per group; 0 and 1 mg/kg/day). Results from our study were mixed, indicating that glandular T4 content sensitivity may be species-specific and influenced by the dose and duration of perchlorate exposure.
Key words: perchlorate, thyroid, rodents