Meeting Abstract
14.6 Sunday, Jan. 4 Effects of pre- and post-hatching perchlorate exposure on the thyroid function and expression of thyroid-responsive genes in Japanese quail embryos and chicks CHEN, Y.; SIBLE, J.C.; MCNABB, F. M. A.*; Virginia Tech, Blacskburg; Virginia Tech, Blacksburg; Virginia Tech, Blacksburg cyrain@vt.edu
The current study examined the effect of maternal exposure to perchlorate, a thyroid disruptor, on Japanese quail embryos and the effect of perchlorate exposure on young Japanese quail chicks. Laying Japanese quail hens were treated with 2000 and 4000 mg/l ammonium perchlorate in drinking water. Eggs from these hens were incubated. Embryos, exposed to perchlorate in the eggs, were sacrificed at day 14 of the 16.5 day incubation period. Quail chicks, 4-5 days old, were treated with 2000 mg/l ammonium perchlorate in drinking water for 2 and 7.5 weeks. Thyroid status and the expression of thyroid-responsive genes, type 2 deiodinase (D2) and RC3 in the brain as well as D2 and spot 14 in the liver, were evaluated. Maternal perchlorate exposure led to embryonic hypothyroidism, which decreased body growth and increased D2 mRNA level in the liver but did not affect the mRNA levels of D2 and RC3 in the brain. Spot 14 mRNA was not detected in embryonic liver. Quail chicks showed early signs of hypothyroidism after 2 weeks of perchlorate exposure and became overtly hypothyroid after 7.5 weeks of exposure as indicated by all thyroid variables measured. D2 mRNA level was increased and spot 14 mRNA level was decreased in the liver of chicks after 2 weeks of exposure but no difference was observed in the mRNA levels of D2 and spot 14 in the liver after 7.5 weeks of exposure. The mRNA level of D2 and RC3 in the brain was not affected by perchlorate-induced hypothyroidism in quail chicks after either 2 or 7.5 weeks of exposure. Perchlorate exposure, both pre-hatching and post-hatching, disrupted thyroid function and affected the expression of hepatic thyroid-responsive genes in developing Japanese quail.
