RESUMO
This is a case report of apparent thyroid structural and functional alteration in a single mouse subjected to low Earth orbit spaceflight for 91 days. Histological examination of the thyroid gland revealed an increase in the average follicle size compared to that of three control animals and three animals exposed to hypergravity (2g) conditions. Immunoblotting analysis detected an increase in two thyroid gland enzymes, sphingomyelinase and sphingomyelin-synthase1. In addition, sphingomyelinase, an enzyme confined to the cell nucleus in the control animals, was found in the mouse exposed to hypogravity to be homogeneously distributed throughout the cell bodies. It represents the first animal observation of the influence of weightlessness on sphingomyelin metabolism.
Assuntos
Hipergravidade , Voo Espacial , Esfingomielinas/metabolismo , Glândula Tireoide/metabolismo , Animais , Núcleo Celular/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Ausência de PesoRESUMO
Although differences in size of the right and left thyroid lobes are well defined, differences in morphology, follicles structure, cAMP production, thyrotropin receptor, and protein involved in cell signalling have not previously been reported. This study provides morpho-functional data of right and left thyroid lobes by biochemical, immunohistochemistry, immunoblotting and immunofluorescence analysis. We demonstrate that, in comparison with the left lobe, the right lobe has a higher activation index, is more sensitive to thyrotropin treatment, is rich in thyrotropin receptor and caveolin 1 involved in thyroid hormone synthesis as well as in epithelial thyroid cell homeostasis, is characterised by a high content of molecules involved in cell signalling such as stat3, raf1, sphingomyelinase and sphingomyelin-synthase whose activity ratio is necessary for epithelial cell activity and finally has more areas calcitonin-dependent. The relation between structure/function of right lobe and its susceptibility to the higher risk of pathological modifications with respect the left lobe is discussed.
Assuntos
Glândula Tireoide/anatomia & histologia , Glândula Tireoide/metabolismo , Animais , Caveolina 1/metabolismo , AMP Cíclico/metabolismo , Técnicas In Vitro , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Receptores da Tireotropina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Esfingomielina Fosfodiesterase/metabolismo , Glândula Tireoide/citologia , Glândula Tireoide/efeitos dos fármacos , Tireotropina/farmacologia , Transferases (Outros Grupos de Fosfato Substituídos)/metabolismoRESUMO
AIM: To study the expression of CD133 and CD34 antigens on cultured human keratocytes over time. METHODS: Primary cultures of human corneal stromal cells were established from explants derived from cadaver eye donors. The cultures were sorted for CD133+ and CD34+ cells using magnetic beads. Both the primary cultures and secondary passages of sorted cells were further analysed by flow cytometry and western blot analysis for expression of the same antigens over time. RESULTS: Four different cell populations-namely, CD133+, CD133-, CD34+ and CD34-, were identified in the culture samples. Two further specific subgroups were identified by flow cytometry: CD133+/CD34- cells and CD133+/CD34+ cells. Expression of CD133 declines more than CD34 with time in cell cultures. Although most cells lost expression of these markers, small populations retained staining up to 5 weeks in culture. CONCLUSION: Human keratocytes express the haematopoietic stem cell markers CD133 and CD34. This expression decreases with time in culture, with most but not all cells losing expression. On the basis of these markers, the corneal stroma shows a heterogeneous population of cells. Expression or down regulation of expression of these molecules could represent different stages of activation of these cells.
