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Mitochondrial metabolism in different thyroid states.

ABSTRACT: The protonmotive force, as well as the mitochondrial and cytosolic concentrations of malate, 2-oxoglutarate, glutamate and aspartate, were determined in livers from hypo-, eu- and hyper-thyroid rats, by density-gradient centrifugation of freeze-clamped livers in non-aqueous solvents [Soboll, Akerboom, Schwenke, Haase & Sies (1980) Biochem. J. 192, 951-954]. The mitochondrial/cytosolic pH difference and the membrane potential were significantly enhanced in hyperthyroid livers compared with the hypothyroid state, resulting in an increased protonmotive force in the presence of thyroid hormones [Soboll & Sies (1989) Methods Enzymol. 174, 118-130]. The mitochondrial concentrations of 2-oxoglutarate, glutamate and aspartate were significantly higher in the euthyroid than in the hypothyroid state, but only slightly higher in the hyperthyroid state. Mitochondrial malate, on the other hand, increased significantly from the hypothyroid to the hyperthyroid state. The mitochondrial/cytosolic concentration gradients were significantly increased in the presence of thyroid hormones only for malate. The changes in steady-state metabolite concentrations reflect a higher substrate supply and a stimulation of mitochondrial metabolism. However, a clear relationship between the increased protonmotive force, as the driving force for mitochondrial metabolite transport, and the subcellular metabolite concentrations is not observable in different thyroid states.

SUBMITTER: Soboll S

PROVIDER: S-EPMC1130656 | biostudies-other | 1992 Jan

REPOSITORIES: biostudies-other

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Project description:1. The actions of the beta-adrenoceptor agonist isoprenaline on glucose and glycogen metabolism, in the presence of various concentrations of insulin, were investigated in isolated soleus muscle preparations taken from eu-, hyper- and hypothyroid rats. 2. Hyperthyroidism, induced by 3,3',5-tri-iodo-D-thyronine (T3) administration for 5 days, increased the rate of lactate formation and suppressed the rate of glycogen synthesis in soleus muscle in response to isoprenaline, even in the presence of physiological or supraphysiological insulin concentrations. 3. Hypothyroidism, induced by administration of 6-n-propyl-2-thiouracil for 4 weeks, decreased the rate of isoprenaline-stimulated lactate formation at all insulin concentrations, but significantly decreased the responsiveness of lactate formation only at low insulin concentrations. In the presence of 100 or 10,000 mu-units of insulin/ml, the ability of isoprenaline to suppress the rate of glycogen synthesis was markedly impaired (inhibition at 100 mu-units of insulin/ml and 1 micro-M-isoprenaline: eu- 72.6 +/- 2.9%; hypo-41.0 +/- 2.1%; P less than 0.001). 4. Hyperthyroidism had no effect on the number or affinity of beta-adrenoceptors, defined by 125I-pindolol binding, or beta-adrenoceptor- or forskolin-stimulated adenylate cyclase activity in membrane preparations of gastrocnemius muscle, whereas hypothyroidism increased the beta-adrenoceptor density and decreased the beta-adrenoceptor-stimulated adenylate cyclase activity, without affecting the receptor affinity or forskolin-stimulated adenylate cyclase activity. 5. It is concluded that there is a complex interplay between insulin, catecholamines and thyroid hormones to regulate skeletal-muscle glucose metabolism. The changes observed in muscles in hypothyroidism may be explained, at least in part, by changes in beta-adrenoceptor-G-protein-adenylate cyclase coupling affecting the generation of cyclic AMP and the regulation of some of the key enzymes of glycogen metabolism; in contrast, the changes observed in muscles in hyperthyroidism do not appear to result from alterations at the level of the receptor-mediated second-messenger generation.

Project description:BackgroundIn recent years, the incidence rate of Thyroid carcinoma (TC) has been increasing worldwide. Thus, research on factors of TC carcinogenesis may promote TC prevention and decrease the incidence rate. There are several studies targeting the correlation between gut microbiota and thyroid disease. Carcinogenesis of several malignancies is influenced by microbiota. However, thyroid microbiome of TC has not been revealed. This study investigated thyroid microbiota in different TC microhabitats.MethodsWe performed 16s rRNA gene sequencing using tumor tissues and matched peritumor tissues from 30 patients with TC to characterize thyroid microbiota.ResultsThe richness and diversity of thyroid microbiota were lower in TC tumor samples than in matched peritumor tissues. At the genus level, the core microbiota of thyroid included Sphingomonas, Comamonas, Acinetobacter, Pseudomonas, Microvirgula, and Soonwooa. The abundance of Sphingomonas and Aeromonas was significantly increased in tumor tissues, while the abundance of Comamonas, Acinetobacter, and Peptostreptococcus was significantly enhanced in peritumor tissues. The combination of Comamonas and Sphingomonas could discriminate tumor samples from peritumor samples with an area under the curve (AUC) of 0.981 (95% confidence interval [CI] 0.949-1.000). The abundance of Sphingomonas was significantly higher in N1 stage than in N0 stage. Sphingomonas could distinguish between N0 and N1 stage with an AUC of 0.964 (95% CI 0.907-1.000).ConclusionsThe microbial diversity and composition were significantly different between peritumor and tumor microhabitats from patients with TC, which may eventually affect TC carcinogenesis and progression. The combination of Comamonas and Sphingomonas could serve as a powerful biomarker for discrimination between tumor and peritumor tissues. Furthermore, the higher abundance of Sphingomonas was correlated with lymph node metastasis, indicating that the abundance of Sphingomonas may indicate a poor prognosis for TC patients, and Sphingomonas may play a role in promoting TC progression.

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Mitochondrial metabolism in different thyroid states.

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