TY - JOUR
T1 - Changes in gastric sodium-iodide symporter (NIS) activity are associated with differences in thyroid gland sensitivity to perchlorate during metamorphosis
AU - Carr, James
AU - Murali, Sharanya
AU - Hu, Fang
AU - Goleman, Wanda
AU - Carr, Deborah
AU - Smith, Ernest
AU - Wages, Mike
N1 - Funding Information:
This research was supported by funding from the U.S. Department of Defense through the Strategic Environmental Research and Development Program under a Cooperative Agreement with the U.S. Air Force, Institute for Environmental Safety and Occupational Health, Brooks Air Force Base (TX, USA). The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the 311 Human Systems Wing/Air Force Institute for Environment, Safety, and Occupational Health Risk Analysis or the U.S. Government. We would like to thank Dr. Brenda Rodgers for commenting on earlier versions of this manuscript and Dr. Todd Anderson for letting us use the ion chromatography system.
Publisher Copyright:
© 2014 Elsevier Inc.
PY - 2015/8/1
Y1 - 2015/8/1
N2 - We investigated stage-dependent changes in sensitivity of the thyroid gland to perchlorate during development of African clawed frog tadpoles (Xenopus laevis) in relation to non-thyroidal iodide transporting tissues. Perchlorate-induced increases in thyroid follicle cell size and colloid depletion were blunted when exposures began at Nieuwkoop-Faber (NF) stage 55 compared to when exposures began at NF stages 49 or 1-10. To determine if the development of other iodide transporting tissues may contribute to this difference we first examined which tissues expressed transcripts for the sodium dependent iodide symporter (NIS). RT-PCR analysis revealed that NIS was expressed in stomach and small intestine in addition to the thyroid gland of X. laevis tadpoles. NIS mRNA was not detected in lung, kidney, skin, gill, muscle, heart or liver. Perchlorate sensitive 125I uptake was found in stomach, lung, kidney, gill, and small intestine but not muscle, liver, or heart. Perchlorate-sensitive 125I uptake by stomach was 6-10 times greater than in any other non-thyroidal tissue in tadpoles. While NF stage 49 tadpoles exhibited perchlorate-sensitive uptake in stomach it was roughly 4-fold less than that observed in NF stage 55 tadpoles. Although abundance of NIS gene transcripts was greater in stomachs from NF stage 55 compared to NF stage 49 tadpoles this difference was not statistically significant. We conclude that gastric iodide uptake increases between NF stages 49 and 55, possibly due to post-translational changes in NIS glycosylation or trafficking within gastric mucosal cells. These developmental changes in gastric NIS gene expression may affect iodide availability to the thyroid gland.
AB - We investigated stage-dependent changes in sensitivity of the thyroid gland to perchlorate during development of African clawed frog tadpoles (Xenopus laevis) in relation to non-thyroidal iodide transporting tissues. Perchlorate-induced increases in thyroid follicle cell size and colloid depletion were blunted when exposures began at Nieuwkoop-Faber (NF) stage 55 compared to when exposures began at NF stages 49 or 1-10. To determine if the development of other iodide transporting tissues may contribute to this difference we first examined which tissues expressed transcripts for the sodium dependent iodide symporter (NIS). RT-PCR analysis revealed that NIS was expressed in stomach and small intestine in addition to the thyroid gland of X. laevis tadpoles. NIS mRNA was not detected in lung, kidney, skin, gill, muscle, heart or liver. Perchlorate sensitive 125I uptake was found in stomach, lung, kidney, gill, and small intestine but not muscle, liver, or heart. Perchlorate-sensitive 125I uptake by stomach was 6-10 times greater than in any other non-thyroidal tissue in tadpoles. While NF stage 49 tadpoles exhibited perchlorate-sensitive uptake in stomach it was roughly 4-fold less than that observed in NF stage 55 tadpoles. Although abundance of NIS gene transcripts was greater in stomachs from NF stage 55 compared to NF stage 49 tadpoles this difference was not statistically significant. We conclude that gastric iodide uptake increases between NF stages 49 and 55, possibly due to post-translational changes in NIS glycosylation or trafficking within gastric mucosal cells. These developmental changes in gastric NIS gene expression may affect iodide availability to the thyroid gland.
KW - Amphibian
KW - Development
KW - Iodide
KW - Metamorphosis
KW - Thyroid
UR - http://www.scopus.com/inward/record.url?scp=84939415805&partnerID=8YFLogxK
U2 - 10.1016/j.ygcen.2014.10.018
DO - 10.1016/j.ygcen.2014.10.018
M3 - Article
C2 - 25448256
VL - 219
SP - 16
EP - 23
JO - General and Comparative Endocrinology
JF - General and Comparative Endocrinology
ER -