Selenium levels in wild-type and TRα1+m mutant mice with or without T3 treatment.

<p>A) Analysis of selenium concentration in serum, urine, liver and kidney of wild-type mice (wt, white bars) and animals heterozygous for a mutant TRα1 (+m, black bars), untreated or treated with supraphysiological doses of thyroid hormone (T3-treated). (##: p<0.01 for genotype, **: p<0.01 for T3 treatment, ***: p<0.001 for T3 treatment, 2-way ANOVA, n = 10 for serum, n = 5 for tissues and urine per group). B) Serum levels of selenium in wild-type (wt, white bars) and TRα1+m mice (+m, black bars) at thermoneutrality (30C). (#: p<0.05 for genotype, p = 0.39 for environmental temperature).</p

Hepatic, renal and serum glutathione-peroxidase activity and serum Sepp concentrations in wild-type and TRα1+m mice with or without T3 treatment.

<p>A) Enzymatic activity of glutathione peroxidase (Gpx) in liver and kidney of untreated and TH treated (T3-treated) wild-type (wt, white bars) and TRα1+m mice (+m, black bars). The activity is normalized against the protein content of the sample. (**: p<0.01 for T3 treatment, ##: p<0.01 for genotype, 2-way ANOVA, n = 5 for each group). B) Enzymatic activity of serum glutathione peroxidase 3 (Serum Gpx) and concentrations of selenium protein P (Serum Sepp) levels in serum of untreated and TH treated (T3-treated) wild-type (wt, white bars) and TRα1+m mice (+m, black bars). (#: p<0.05 for genotype, **: p<0.01 for T3 treatment, 2-way ANOVA).</p

Hepatic and renal gene expression in wild-type and TRα1+m mice with or without T3 treatment.

<p>A) Expression profiling of genes involved in selenium metabolism in livers of untreated and TH treated (T3-treated) wild-type (wt, white bars) and TRα1+m mice (+m, black bars). The expression is normalized against the housekeeping gene HPRT. Sepp: selenoprotein P, SecS: selenocysteine t-RNA synthase, Sebp1: selenium binding protein 1, Pstk: phosphoseryl-tRNA kinase, EFsec: selenocysteine-specific elongation factor, Sephs2: selenophosphate-synthetase 2, mScLy: selenocysteine lyase, GPx1: glutathione peroxidase 1, Dio1: deiodinase type I, SelW/SelH: selenoprotein W or H. B) Expression profiling of genes involved in selenium metabolism in kidneys of untreated and TH treated (T3-treated) wild-type (wt, white bars) and TRα1+m mice (+m, black bars). The expression is normalized against the housekeeping gene HPRT. Dio1: deiodinases type I, Sepp: selenoprotein P, Gpx1: glutathione peroxidase 1, Gpx3: glutathione peroxidase 3, SelW/SelH: selenoprotein W or H. (###: p<0.001 for T3 treatment of the wild-type, *: p<0.05 for T3 treatment, **: p<0.01 for T3 treatment, ***: p<0.001 for T3 treatment, 2-way ANOVA with Bonferroni post hoc test, n = 5 for each group).</p

Schematic illustration of the feed-forward reaction which might take place during critical illness.

<p>Declining serum selenium concentrations cause impaired selenoprotein expression in the tissues. In parallel, impaired deiodinase expression leads to low T3 concentrations. Both pathways might aggravate each other if the declining selenium and T3 concentrations are not compensated for by a combined supplementation effort aiming to meet the patient's Se and TH requirements.</p

Effects of maternal or postnatal hyperthyroidism on serum selenium.

<p>Serum levels of selenium in wild-type (wt, white bars) and TRα1+m mutants (+m, black bars) born by hyperthyroid TRβ−/− mothers (high maternal TH), with inactivation of TRβ, which causes endogenous postnatal hyperthyroidism (high endogenous TH), or a combination of both (high endogenous, high maternal TH). (***: p<0.001 for T3 treatment, 2-way ANOVA, n = 5 per group).</p

DataSheet_1_Cardiac recovery from pressure overload is not altered by thyroid hormone status in old mice.docx

IntroductionThyroid hormones (THs) are known to have various effects on the cardiovascular system. However, the impact of TH levels on preexisting cardiac diseases is still unclear. Pressure overload due to arterial hypertension or aortic stenosis and aging are major risk factors for the development of structural and functional abnormalities and subsequent heart failure. Here, we assessed the sensitivity to altered TH levels in aged mice with maladaptive cardiac hypertrophy and cardiac dysfunction induced by transverse aortic constriction (TAC).MethodsMice at the age of 12 months underwent TAC and received T4 or anti-thyroid medication in drinking water over the course of 4 weeks after induction of left ventricular pressure overload.ResultsT4 excess or deprivation in older mice had no or only very little impact on cardiac function (fractional shortening), cardiac remodeling (cardiac wall thickness, heart weight, cardiomyocyte size, apoptosis, and interstitial fibrosis), and mortality. This is surprising because T4 excess or deprivation had significantly changed the outcome after TAC in young 8-week-old mice. Comparing the gene expression of deiodinases (Dio) 2 and 3 and TH receptor alpha (TRα) 1 and the dominant-negative acting isoform TRα2 between young and aged mice revealed that aged mice exhibited a higher expression of TRα2 and Dio3, while expression of Dio2 was reduced compared with young mice. These changes in Dio2 and 3 expressions might lead to reduced TH availability in the hearts of 12-month-old mice accompanied by reduced TRα action due to higher TRα2.DiscussionIn summary, our study shows that low and high TH availability have little impact on cardiac function and remodeling in older mice with preexisting pressure-induced cardiac damage. This observation seems to be the result of an altered expression of deiodinases and TRα isoforms, thus suggesting that even though cardiovascular risk is increasing with age, the response to TH stress may be dampened in certain conditions.</p