Thyroid-stimulating hormone inhibits glucose transporter4 translocation through an extra-thyroidal pathway in 3T3-L1 adipocytes / 中华老年医学杂志

ABSTRACT

Objective To test thyroid-stimulating hormone (TSH) suppress GLUT4 expression and translocation by stimulating TNF-α secretion in 3T3-L1 adipocytes via a cAMP-PKA pathway.Methods 3T3-L1 preadipocytes were induced to differentiate into adipocytes.The adipocytes were treated with bovine TSH,Forskolin,H89 and Rapamycin,respectively.The concentration of TNF-α in the cell culture medium was measured by ELISA.The level of GLUT4 mRNA in adipocytes was assessed by real time polymerase chain reaction.Protein levels of GLUT4 in total cell lysates and plasma membrane lysates were quantified by Western blotting.Results Incubating 3T3-L1 adipocytes with TSH markedly increased the concentration of TNF-α in medium in a time-and dosedependent manner (P ＜ 0.05); meanwhile,the levels of GLUT4 mRNA and total and plasma membrane GLUT4 protein were decreased in a dose-dependent manner (P＜0.05 or ＜0.01).H89 and rapamycin could block the above effects respectively (326.7±43.2 vs.341.9±12.0,P＞0.05).However,there was no statistical difference in the TNF-α levels between stimulation with 1 μmmol/L forskolin versus 0.04 μmmol/L bovine TSH (481.9± 28.4 vs.522.7± 36.2,P＞0.05).Conclusions TSH can down-regulate GLUT4 expression and translocation in 3T3-L1 adipocytes by stimulating TNF-α secretion through a cAMP-PKA pathway.