Calsequestrin is the main calcium binding protein of the sarcoplasmic reticulum, serving as an important regulator of Ca 2+ . In mammalian muscles, it exis ts as a skeletal isoform found in fast- and slow-twitch skeletal muscles and a cardiac isoform expressed in the heart and slow-twitch muscles. Recently, many excellent reviews that summarised in great detail various aspects of the calsequestrin structure, localisation or function both in skeletal and cardiac muscle have appeared. The present review focuses on skeletal muscle: information on cardiac tissue is given, where differences between both tissues are functionally important. The article reviews the known multiple roles of calsequestrin including pathology in order to introduce this topic to the broader scientific community and to stimulate an interest in this protein. Newly we describe our results on the effect of thyroid hormones on skeletal and cardiac calsequestrin expression and discuss them in the context of available literary data on this topic., P. Novák, T. Soukup., and Obsahuje bibliografii a bibliografické odkazy
Thyroid hormones are powerful modulators of heart function and susceptibility to arrhythmias via both genomic and non-genomic actions. We aimed to explore expression of electrical coupling protein connexin-43 (Cx43) in the heart of rats with altered thyroid status and impact of omega-3 polyunsaturated fatty acids (omega-3) supplementation. Adult male Lewis rats were divided into following six groups: euthyroid controls, hyperthyroid (treated with T3) and hypothyroid (treated with methimazol) with or without six-weeks lasting supplementation with omega-3 (20 mg/100 g/day). Left and right ventricles, septum and atria were used for immunoblotting of Cx43 and protein kinase C (PKC). Total expression of Cx43 and its phosphorylated forms were significantly increased in all heart regions of hypothyroid rats compared to euthyroid controls. In contrast, the total levels of Cx43 and its functional phosphorylated forms were decreased in atria and left ventricle of hyperthyroid rats. In parallel, the expression of PKC epsilon that phosphorylates Cx43, at serine 368, was increased in hypothyroid but decreased in hyperthyroid rat hearts. Omega-3 intake did not significantly affect either Cx43 or PKC epsilon alterations. In conclusion, there is an inverse relationship between expression of cardiac Cx43 and the levels of circulating thyroid hormones. It appears that increased propensity of hyperthyroid while decreased of hypothyroid individuals to malignant arrhythmias may be in part attributed to the changes in myocardial Cx43., B. Szeiffová Bačová, T. Egan Beňová, C. Viczenczová, T. Soukup, H. Rauchová, S. Pavelka, V. Knezl, M. Barančík, N. Tribulová., and Obsahuje bibliografii
b1_We newly elaborated and adapte d several radiometric enzyme assays for the determination of activities of the key enzymes engaged in the biosynthesis (thyroid peroxidase, TPO) and metabolic transformations (conjugating enzymes and iodothyronine deiodinases, IDs) of thyroid hormones (THs) in the thyroid gland and in peripheral tissues, especially in white adipose tissue (WAT). We also elaborated novel, reliable radiometric methods for extremel y sensitive determination of enzyme activities of IDs of types 1, 2 and 3 in microsomal fractions of different rat and hum an tissues, as well as in homogenates of cultured mammalia n cells. The use of optimized TLC separation of radioactive products from the unconsumed substrates and film-less autoradiography of radiochromatograms, taking advantage of storage phosphor screens, enabled us to determine IDs enzyme activities as low as 10-18 katals. In studies of the interaction of fluoxetine (Fluox) with the metabolism of THs, we applied adapted radiometric enzyme assays for iodothyronine sulfotransferases (ST) and uridine 5’-diphosphoglucuronyltransferase (UDP-GT). Fluox is the most frequently used representative of a new group of non-tricyclic antidepressant drugs - selective serotonin re-uptake inhibitors. We used the elaborated assays fo r quantification the effects of Fluox and for the assessment of th e degree of potential induction of rat liver ST and/or UDP-GT enzyme activities by Fluox alone or in combination with T3 . Furthermore, we studied possible changes in IDs activities in murine adipose tissue under the conditions that promoted either tissue hypertrophy (obesogenic treatment) or involution (caloric restriction), and in response to leptin, using our newly developed radiometric enzyme assays for IDs., b2_Our results suggest that deiodinase D1 has a functional role in WAT, with D1 possibly being involved in the control of adipose tissue metabolism and/or accumulation of the tissue. Significant positive correlation between specific enzyme activity of D1 in WAT and plasma leptin levels was found. The newly developed and adapted radiometric enzyme assays proved to be very useful tools for studies of factors modulating THs metabolism, not only in model animals but also in clinical studies of human obesity., S. Pavelka., and Obsahuje bibliografii a bibliografické odkazy
We have analyzed the influence of altered thyroid hormone levels on changes of MyHC protein isoforms and their mRNA transcripts in the soleus muscle of 2-, 4- and 7-month-old euthyroid (EU), hypothyroid (HY) and hyperthyroid (TH) female inbred Lewis strain rats (methimazole and T3 treatment started 3 to 4 weeks after birth). We have found that the content of the dominant MyHC 1 isoform gradually increased in the EU rats and that this increase was more progressive in the HY rats at all three stages. On the other hand, in the TH rats the content of MyHC 1 isoform was the highest in the 2-month-old rats and it decreased with an increasing length of T3 treatment. The content of the minor 2a MyHC isoform followed the opposite pattern. In contrast to the protein isoforms, the MyHC mRNA transcripts remained at similar levels. Nevertheless, in general, the MyHC 1 mRNA level was decreased and MyHC 2a transcript increased in the TH rats, while the opposite changes occurred in the HY rats. Our results thus suggest that in the rat soleus muscle, both increased and decreased levels of thyroid hormones speed up the formation of an adult slow phenotype which is demonstrated by the precocious appearance of the slow MyHC 1 isoform, but opposite to the hypothyroid status, a longer T3 application promotes the expression of the faster MyHC 2a isoform., A. Vadászová-Soukup, T. Soukup., and Obsahuje bibliografii a bibliografické odkazy
Thyroid hormones (THs) play multiple roles in the organism and alterations of their levels can result in many pathological changes. Currently, we use hypert hyroid and hypothyroid rats as “models of a diseased organi sm” and analyze whether n-3 polyunsaturated fatty acids (n-3 PUFA) administration can ameliorate TH-induced pathop hysiological changes. We investigate myosin heavy chain composition, calsequestrin levels, changes in cardiac tissue remodeling and cell-to-cell communication, expression of protein kinases, mitochondrial functions, oxidative stress mark ers and cell death, changes in serum lipid levels, activities of key enzymes of thyroid hormone metabolism, activity of acetyl choline esterase and membrane anisotropy, as well as mobile behavior and thermal sensitivity. Additionally we also mention our pilot experiments dealing with the effect of statin administration on skeletal muscles and sensory functions. As THs and n-3 PUFA possess multiple sites of potential action, we hope that our complex research will contribute to a better understanding of their actions, which can be useful in the treatment of di fferent pathophysiological events including cardiac insufficiency in humans., T. Soukup., and Obsahuje bibliografii a bibliografické odkazy
We measured hormonal levels in blood samples from pulmonary and radial arteries in 117 patients undergoing aorto-coronary by-pass surgery with the aim of investigating the role of the pulmonary vessel endothelium in hormone metabolism. Insulin and glucagon concentrations were significantly higher in pulmonary artery blood with respect to radial artery blood (73±65 vs. 65±47 pmol/l, p<0.005, and 80+49 vs. 73+51 ng/l, p<0.01, respectively), while no difference was found for growth hormone, prolactin, C peptide, insulin-like growth factor I, follicle stimulating hormone, luteinizing hormone, thyroid stimulating hormone, parathyroid hormone, thyroglobulin, triiodothyronine, thyroxine, free triiodothyronine, and free thyroxine. Moreover, prolactin concentrations were more than twice the normal levels, this being an effect of propafol and the opiate fentanyl used for the general anesthesia. Assuming that the arteriovenous differences observed are a marker of peptide hormone degradation, our study has demonstrated that with similar kinetics insulin and glucagon secreted into portal circulation and escaping from hepatic extraction undergo further homeostatic removal of about 9-10 % in the pulmonary circulation before entering the general circulation., G. Aliberti, I. Pulignano, M. Proietta, F. Miraldi, L. Cigognetti, L. Tritapepe, C. Di Giovanni, R. Arzilla, E. Vecci, M. Toscano., and Obsahuje bibliografii
There is accumulating evidence showing that ischemic preconditioning (PC) may lose its cardioprotective effect in the diseased states. The present study investigated whether PC can be effective in hypothyroidism, a clinical condition which is common and often accompanies cardiac diseases such as heart failure and myocardial infarction. Hypothyroidism was induced in rats by 3-week administration of 6n-propyl-2-thiouracil in water (0.05 %). Normal and hypothyroid hearts (HYPO) were perfused in Langendorff mode and subjected to 20 min of zero-flow global ischemia and 45 min of reperfus ion. A preconditioning protocol (PC) was also applied prior to ischemia. HYPO hearts had significantly improved post-ischemic recovery of left ventricular developed pressure, end-diastolic pressure and reduced lactate dehydrogenase release. Furthermore, phospho-JNK and p38 MAPK levels after ischemia and reperfusion were 4.0 and 3.0 fold lower in HYPO as compared to normal hearts ( P<0.05). A different response to PC was observed in normal than in HYPO hearts. PC improved the post-ischemic recovery of function and reduced the extent of injury in normal hearts but had no additional effect on the hypothyroid hearts. This response, in the preconditioned normal hearts, resulted in 2.5 and 1.8 fold smaller expression of the phospho-JNK and phospho-p38 MAPK levels at the end of reperfusion, as compared to non-PC hearts ( P<0.05), while in HYPO hearts, no additional reduction in the phosphorylation of these kinases was observed after PC. Hypothyroid hearts appear to be tolerant to ischemia-reperfusion injury. This response may be, at least in part, due to the down-regulation of ischemia-reperfusion induced activation of JNKs and p38 MAPK kinases. PC is not associated with further reduction in the activation of these kinases in the hypothyroid hearts and fails to confer added protection in those hearts., I. Mourouzis ... [et al.]., and Obsahuje seznam literatury
Although the mutations in MC4R gene became known as the most common genetic cause of human obesity, the effect of rs12970134 A/G near MC4R gene on insulin resistance has been described. The aim of this study was to determine the effect of rs12970134 on obesity, hormone levels, and glucose metabolism in a cohort of women varying in glucose tolerance: 850 normoglycemic women, 423 diagnosed with polycystic ovary syndrome (PCOS), 402 gestational diabetics (GDM), and 250 type 2 diabetic (T2D) women. We did not confirm the explicit effect of rs12970134 on obesity. However, the influence of the A-allele on body adiposity index was observed in a cohort of women diagnosed with PCOS. In normoglycemic women, the A-allele carriership was associated with lower fasting levels of glucose, insulin, C-peptide, and index of insulin resistance. Furthermore, higher levels of growth hormone, leptin and SHBG, and lower levels of fT3, testosterone, and androstenedione were recorded in normoglycemic A-allele carriers. In conclusion, the study presents the evidence of the impact of rs12970134 on complex hypothalamic regulations., O. Bradnová, D. Vejražková, M. Vaňková, P. Lukášová, J. Včelák, S. stanická, K. Dvořáková, B. Bendlová., and Obsahuje bibliografii
Adipose tissue is an important target for thyroid hormones (TH). However, the metabolism of TH in white adipose tissue is poorly characterized. Our objective was to describe possible changes in activities of TH-metabolizing enzymes in white adipose tissue, and the role of TH metabolism in the tissue during obesogenic treatment, caloric restriction and in response to leptin in mice. Activity of type I iodothyronine 5’-deiodinase (D1) in white fat was stimulated by a high-fat diet, which also increased plasma leptin levels, while brown adipose tissue D1 activity did not change. Caloric restriction decreased the activity of D1 in white fat (but not in the liver), reduced leptin levels, and increased the expression of stearoyl CoA desaturase 1 (SCD-1), a marker and mediator of the effect of leptin on tissue metabolism. Leptin injections increased D1 activity and down-regulated SCD-1 in white fat. Our results demonstrate changes in D1 activity in white adipose tissue under the conditions of changing adiposity, and a stimulatory effect of leptin on D1 activity in the tissue. These results suggest a functional role for D1 in white adipose tissue, with D1 possibly being involved in the control of adipose tissue metabolism and/or accumulation of the tissue., Z. Macek Jílková ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Recently, we have established that slow soleus (SOL) and fast extensor digitorum longus (EDL) muscles of euthyroid (EU) Lewis rats posses the same proportions between their four myosin heavy chain (MyHC) mRNAs , protein isoforms and fiber types as determined by real time RT-PCR, SDS-PAGE and 2-D stereological fiber type analysis, respectively. In the present paper we investigated if these proportions are maintained in adult Lewis rats with hyperthyroid (HT) and hypothyroid (HY) status. Although HT and HY states change MyHC isoform expression, results from all three methods showed that proportion between MyHC mRNA-1, -2a, -2x/d, -2b , protein isoforms MyHC-1, -2a, -2x/d, -2b and to lesser extent also fiber types 1, 2A, 2X/D, 2B were preserved in both SOL and EDL muscles. Furthermore, in the SOL muscle mRNA expression of slow MyHC-1 remained up to three orders higher compared to fast MyHC transcripts, which explains the predominance of MyHC-1 isoform and fiber type 1 even in HT rats. Although HT status led in the SOL to increased expression of MyHC-2a mRNA, MyHC-2a isoform and 2A fibers, it preserved extremely low expression of MyHC-2x and -2b mRNA and protein isoforms, which explains the absence of pure 2X/D and 2B fibers. HY status, on the other hand, almost completely abolished expression of all three fast MyHC mRNAs , MyHC protein isoforms and fast fiber types in the SOL muscle. Our data present evidence that a correlation between mRNA , protein content and fiber type composition found in EU status is also preserved in HT and HY rats., T. Soukup, M. Diallo., and Obsahuje bibliografii