Adipocytes are an important target tissue for thyroid hormone action, but little is known of the mechanisms of thyroid hormone entry into the cells. The present results show a strong interaction between transport of iodothyronines [L-thyroxine (T4), L-triiodothyronine (T3), reverse T3 (rT3)], aromatic amino acids, and the System L amino acid transport inhibitor 2-amino[2,2,1]heptane-2-carboxyli...

Thyroid hormones are required for human brain development, but data on local regulation are limited. We describe the ontogenic changes in T(4), T(3), and rT(3) and in the activities of the types I, II, and III iodothyronine deiodinases (D1, D2, and D3) in different brain regions in normal fetuses (13-20 wk postmenstrual age) and premature infants (24-42 wk postmenstrual age). D1 activity was un...

We report that aurone derivatives of plant extracts produce potent, dose-dependent, and ultimately complete inhibition of three different metabolic monodeiodination pathways catalyzed by rat liver microsomal type I iodothyronine deiodinase. These data show that (3'),4',4,6-(tetra)trihydroxyaurones are the most potent naturally occurring plant-derived inhibitors of this deiodinase enzyme (IC50 V...

Normal level of thyroid hormone is important for normal hepatic function as it maintains the metabolism of bilirubin by playing a role in the enzymatic activity of glucuronyl transferase and by regulating the level of ligandin. The liver in turn glucuronidates and sulphates the thyroid hormone, excretes into bile and regulates their systemic endocrine effects. Therefore, hepatic dysfunction is ...

Neonatal changes in plasma total and free iodothyronine levels were monitored in 18 Limousin X Romanov suckling lambs (experiment 1) and 24 Limousin X Romanov animals bottle-fed in standardized conditions (experiment 2). In the two experiments, plasma free T3 levels were closely related to total T3 levels, whereas some differences could be observed between total and free plasma T4 levels. The n...

The main object of the present study was to explore the effect on thyroidal proteins following mild iodine deficiency (ID)-induced maternal hypothyroxinemia during pregnancy and lactation. In the present study, we established a maternal hypothyroxinemia model in female Wistar rats by using a mild ID diet. Maternal thyroid iodine content and thyroid weight were measured. Expressions of thyroid-a...

It is not clear whether the muscle wasting commonly observed in hyperthyroidism is due to alteration in the rate of protein synthesis or degradation. The effect of experimental hyperthyroidism on skeletal-muscle proteolysis in the rat was studied by measuring alanine and tyrosine release from isolated skeletal muscles in vitro and 3-methyl-histidine excretion in vivo. Alanine release from the i...

The aim of the present study was to determine whether there was any correlation between serum thyroid hormones, lipids, lipoproteins and the activities of erythrocyte superoxide dismutase (SOD) and glutathione peroxidase (GPX) in adult nonpregnant uniparous Iranian pure bred fat-tailed ewes. Blood samples (10 mL) were taken from the jugular vein of 30 clinically healthy Iranian adult nonpregnan...