Thyroid hormone and diabetes:an anti-apoptotic pro-survival opportunity for pancreatic b cells.

Pancreatic β cell loss is the key factor in the pathogenesis of both type 1 and type 2 diabetes, being mainly due to apoptosis of the β cell. Therefore, it is conceivable that a valuable approach to treat or even to prevent the onset of diabetes may imply an anti-apoptotic pro-survival therapy of β cell. Ex vivo islet cell culture in the presence of stimulating factors prior to transplantation is considered a good strategy in contrast to the short conclusion of islets transplantation. Previously, I demonstrated how T3 can increase β cell function via specific activation of Akt; therefore I, firstly, hypothesized that thyroid hormone T3 can be considered a promising candidate for the in vitro expansion of islet cell mass. Rat pancreatic islets have been isolated by collagenase digestion and cultured in the presence or not of T3 10⁻⁷ M. Islets viability has been evaluated by two different dyes, one cell-permeable green fluorescent and propidium iodide, and by the analysis of core cell damage upcoming. Moreover, islets function has been evaluated by insulin secretion. The ability of β cells to counteract apoptosis induced by streptozotocin has been analyzed by TUNEL assay. In addition, core cell damage was sensibly reduced by T3, suggesting the preservation of the β cells integrity during the culture period. I demonstrated that treatment of primary cultures of rat pancreatic islets with T3 results in augmented β-cell vitality and function. Since even insulin secretion was sensibly augmented by T3 stimulation. Moreover the strong increment shown in Akt activation suggests the involvement of this pathway in the observed phenomena. This study indicate T3 as a good factor to improve ex vivo islets cell culture. In the second part of my study I demonstrated that the thyroid hormone T3 counteracts the onset of a Streptozotocin (STZ) induced diabetes in wild type mice. To test my hypothesis diabetes has been induced in Balb/c male mice by multiple low dose Streptozotocin injection and a group of mice was contemporaneously injected with T3. After 48 h mice were tested for glucose tolerance test, insulin serum levels and then sacrificed. Whole pancreata were utilized for morphological and biochemical analyses, while protein extracts and RNA were utilized for expression analyses of specific molecules. The results showed that islets from T3 treated mice were comparable to age- and sex-matched control, untreated mice in number, shape, dimension, consistency, ultrastructure, insulin and glucagon levels, TUNEL positivity and caspases activation, while all the cited parameters and molecules were altered by STZ alone. The T3-induced pro survival effect was associated with a strong increase in phosphorylated Akt. Moreover, T3 administration prevented the STZ-dependent alterations in glucose blood level, both during fasting and after glucose challenge, as well as in insulin serum level. In conclusion I demonstrated that T3 could act as a protective factor against STZ induced diabetes

Thyroid Hormone T3 Counteracts STZ Induced Diabetes in Mouse

This study intended to demonstrate that the thyroid hormone T3 counteracts the onset of a Streptozotocin (STZ) induced diabetes in wild type mice. To test our hypothesis diabetes has been induced in Balb/c male mice by multiple low dose Streptozotocin injection; and a group of mice was contemporaneously injected with T3. After 48 h mice were tested for glucose tolerance test, insulin serum levels and then sacrified. Whole pancreata were utilized for morphological and biochemical analyses, while protein extracts and RNA were utilized for expression analyses of specific molecules. The results showed that islets from T3 treated mice were comparable to age- and sex-matched control, untreated mice in number, shape, dimension, consistency, ultrastructure, insulin and glucagon levels, Tunel positivity and caspases activation, while all the cited parameters and molecules were altered by STZ alone. The T3-induced pro survival effect was associated with a strong increase in phosphorylated Akt. Moreover, T3 administration prevented the STZ-dependent alterations in glucose blood level, both during fasting and after glucose challenge, as well as in insulin serum level. In conclusion we demonstrated that T3 could act as a protective factor against STZ induced diabetes

Heterogeneity of propyl-ammonium nitrate solid phases obtained under high pressure

A recent work reported on different solid phases obtained on the protic ionic liquid propyl-ammonium nitrate (PAN) under a pressure up to 2 GPa. However, the experimental parameters and measurement protocols driving the solidification process were not clarified. Here, we report on and discuss three different Raman measurements on PAN carried out over different pressure ranges (up to 4 GPa). Exploiting different pressure increasing rates for each measurement we obtained a variety of solid phases. The differences between these phases are highlighted by visual inspection, by different solidification pressure values and by the Raman spectroscopic features relative to the anion stretching mode and to the cation alkyl chain vibration. Our results indicate different local structures surrounding the ionic couple in the solid phase and the capability of pressure to lock the cation alkyl chain in conformations different from those of the liquid state. These evidences also suggest the use of systematic and careful measurement protocols in order to reproduce a particular solid phase of PAN under pressure. (C) 2014 Elsevier Ltd. All rights reserved

Thyroid Hormones (T3 and T4): Dual Effect on Human Cancer Cell Proliferation

Several findings suggest that the patient's hormonal context plays a crucial role in determining cancer outcome. The exact nature of thyroid hormone action on tumour growth has not been established yet, in fact contrasting data show thyroid hormones have a promotory or an inhibitory action on cancer cell proliferation depending on the case. We hypothesized that not only tissue specificity, but also specific mutations occurring during tumoral development in different thyroid hormone cellular targets are responsible for this dual effect. To test our hypothesis we analysed, by time-course and bromodeoxyuridine assay, thyroid hormone effects on the proliferation of six cancer cell lines originating from the same tissue or organ but carrying different mutations (in phospho-inositide 3 kinase or β-catenin genes). The data obtained in this study show how mutations that affect the balance between degradation and stabilization of β-catenin assume a remarkable importance in determining the cell-specific thyroid hormone effect on cell growth

Thyroid Hormone Protects from Fasting-Induced Skeletal Muscle Atrophy by Promoting Metabolic Adaptation

Thyroid hormones regulate a wide range of cellular responses, via non-genomic and genomic actions, depending on cell-specific thyroid hormone transporters, co-repressors, or co-activators. Skeletal muscle has been identified as a direct target of thyroid hormone T3, where it regulates stem cell proliferation and differentiation, as well as myofiber metabolism. However, the effects of T3 in muscle-wasting conditions have not been yet addressed. Being T3 primarily responsible for the regulation of metabolism, we challenged mice with fasting and found that T3 counteracted starvation-induced muscle atrophy. Interestingly, T3 did not prevent the activation of the main catabolic pathways, i.e., the ubiquitin-proteasome or the autophagy-lysosomal systems, nor did it stimulate de novo muscle synthesis in starved muscles. Transcriptome analyses revealed that T3 mainly affected the metabolic processes in starved muscle. Further analyses of myofiber metabolism revealed that T3 prevented the starvation-mediated metabolic shift, thus preserving skeletal muscle mass. Our study elucidated new T3 functions in regulating skeletal muscle homeostasis and metabolism in pathological conditions, opening to new potential therapeutic approaches for the treatment of skeletal muscle atrophy

The thyroid hormone T3 improves function and survival of rat pancreatic islets during in vitro culture

Ex vivo islet cell culture in the presence of stimulating factors prior to transplantation is considered a good strategy in contrast to the short conclusion of islets transplantation. Previously, we demonstrated how T3 can increase beta-cell function via specific activation of Akt; therefore we hypothesized that thyroid hormone T3 can be considered a promising candidate for the in vitro expansion of islet cell mass. Rat pancreatic islets have been isolated by the collagenase digestion and cultured with or without the presence of the thyroid hormone T3 10(-7) M. Islets viability has been evaluated by the use of two different dyes, one cell-permeable green fluorescent dye and propidium iodide, and by the analysis of core cell damage upcoming. Moreover, islets function has been evaluated by insulin secretion. The ability of beta-cells to counteract apoptosis induced by streptozotocin has been analyzed by TUNEL assay. We demonstrated that treatment of primary cultures of rat pancreatic islets with T3 results in augmented beta-cell vitality with an increase of their functional properties. In addition, a sensible reduction of the core cell damage has been observed in the T3 treated islets, suggesting the preservation of the beta-cells integrity during the culture period. Nonetheless, the insulin secretion is sensibly augmented after T3 stimulation. The strong increment shown in Akt activation suggests the involvement of this pathway in the observed phenomena. In conclusion we indicate T3 as a good factor to improve ex vivo islets cell culture