3'-monoiodothyronine sulfate and Triac sulfate are thyroid hormone metabolites in developing sheep.
We used novel 3'-monoiodothyronine sulfate (3'-T1S) and 3,3',5-triiodothyroacetic acid sulfate (TriacS) RIAs to characterize sulfation pathways in fetal thyroid hormone metabolism. 3'-T1S and TriacS levels were measured in serum samples obtained from fetal (n = 21, 94-145 d gestational age), newborn (NB, n = 5), and adult sheep (AD, n = 5) as well as from fetuses after total thyroidectomy (Tx), or sham-operated twin fetuses controls, conducted at gestational age 110-113 d (n = 5). Peak levels (expressed as ng/dL) of both 3'-T1S and TriacS occurred at 130 d gestation. These levels in fetuses were higher than those in NB and AD. In Tx fetuses, there was a significant decrease in the mean serum level of 3'-T1S, but not TriacS. The decrease in 3'-T1S in Tx is similar to that observed for thyroxine sulfate (T4S) and 3,3',5'-triiodothyronine sulfate (rT3S), whereas TriacS levels were not altered in the hypothyroid state, similarly to 3,3',5-triiodothyronine sulfate (T3S). These data demonstrate that 3'-T1S and TriacS are normal thyroid hormone metabolites in ovine serum and that TriacS is likely derived from T3S or from the same precursor(s) as T3S.
Wu
Sing-Yung
SY
Department of Veterans Affairs Medical Center, Nuclear Medicine and Medical Services, Long Beach, California 90822, USA. sing.wu@va.gov
Polk
Daniel H
DH
Huang
Wen-Sheng
WS
Ho
Eugene
E
Kattan
Jaffer M
JM
Fisher
Delbert A
DA
D000818:Animals; D005260:Female; D018507:Gene Expression Regulation, Developmental; D008954:Models, Biological; D011247:Pregnancy; D011270:Pregnancy, Animal; D011863:Radioimmunoassay; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012756:Sheep; D013431:Sulfates / Q000494:pharmacology*; D013963:Thyroid Hormones / Q000378:metabolism*; D013970:Thyronines / Q000494:pharmacology*; D013997:Time Factors; D014284:Triiodothyronine / Q000031:analogs & derivatives* / Q000494:pharmacology
D013431:Sulfates; D013963:Thyroid Hormones; D013970:Thyronines; D014284:Triiodothyronine; C010642:3,3',5-triiodothyroacetic acid; C019017:3'-monoiodothyronine