Respuesta innata de los adipocitos en el metabolismo de fragmentos de 3c en el tejido adiposo blanco e influencia de la insulina
- Autores: Ana Cecilia Ho Palma
- Directores de la Tesis: José Antonio Fernández López (dir. tes.), Xavier Remesar Betlloch (codir. tes.)
- Lectura: En la Universitat de Barcelona ( España ) en 2018
- Idioma: español
- Tribunal Calificador de la Tesis: Maria Cinta Blade Segarra (presid.), Dolores Serra Cucurull (secret.), Daniel Sanchis Morales (voc.)
- Programa de doctorado: Programa de Doctorado en Alimentación y Nutrición por la Universidad de Barcelona
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
Our research group has observed that both 3T3L1 cells and white adipose tissue in vivo are able to release, from glucose, large amounts of lactate under aerobic conditions and glycerol in greater quantity than which can be justified by lipolysis.
To study why adipocytes, act mainly in a glycolytic manner producing 3C fragments without being affected by hypoxia, we developed the necessary methodology applied to primary cultures. Since white adipose tissue is composed by other cell types, we also check whether hypoxia affects the stromal fraction cells in the same way. White adipose tissue responds to signals produced by the body as hormones, so we decided to study in adipocytes and the stromal fraction, how insulin can affect the adipocytes metabolism and their innate response, that is without any external stimulus.
The results indicate that white adipose tissue has a high metabolic activity in relative terms since, despite its small amount of "living" mass (only 1.3% of the total), adipose cells produce and release large amounts of 3C fragments. In adipocytes, lactate is produced from glucose, independently of the presence of oxygen and insulin, to be exported to other cells and used as an energy source. This idea is reinforced by the fact that at higher concentrations of glucose, more lactate is produced. However, although the stromal fraction cells also produce large amounts of lactate, this process is not influenced by glucose concentrations. On the other hand, glycerol is produced only by adipocytes, being regulated by insulin and constant over time. However, initially glycerol comes from the glycolytic pathway, when the glucose concentration is high, but when it is low it comes from lipolysis. At 48 h, its origin changes to glycolytic-lipolytic, except at 3.5 mM glucose. While free fatty acids are recycled to form triacyclglycerols, very little 14C glucose is incorporated over time, indicating limited lipogenesis. But when insulin is added, this lipogenesis is promoted, even though at the same time the hormone limits, at the beginning, the incorporation of glycerol-3P for the synthesis of triacylglycerols.
The coexistence of these two processes, lipogenic and glycolytic simultaneously, is probably a consequence to prevent the accumulation of energy excess as a defense mechanism against "glycolipotoxicity", and a way to supply easily usable energy by other tissues in the form of 3C fragments.
