title: Ceramide mediates inhibition of the Akt/eNOS pathway by high levels of glucose in human vascular endothelial cells.
abstract: OBJECTIVE
  To investigate how ceramide mediates the effects of high-glucose-induced inhibition of the Akt/endothelial nitric oxide synthase (eNOS) signalling pathway in human vascular endothelial cells (HUVECs).
  
  
  METHODS
  NO levels were determined by ELISA. Endogenous ceramide levels were determined using a liquid chromatography-mass spectrometry assay. Akt and eNOS protein expressions were determined by Western blotting.
  
  
  RESULTS
  High-glucose levels induce ceramide accumulation in a dose- and time-dependent manner (p<0.05). We also show that exposure of HUVECs to high-glucose conditions inhibits the insulin-mediated activation of Akt/eNOS signalling and the subsequent NO generation in a dose-dependent manner (p<0.05). Preventing de novo ceramide synthesis attenuated the antagonistic effects of high-glucose levels on the Akt/eNOS signalling pathway (p<0.05); conversely, inducing ceramide build-up augmented the inhibitory effects of high-glucose levels on the Akt/eNOS signalling pathway (p<0.05).
  
  
  CONCLUSIONS
  Ceramide is both necessary and sufficient for mediating the inhibition of the Akt/eNOS signalling pathway by high-glucose levels in endothelial cells.
authors: Department of Endocrinology, Central South University, Changsha, China.
authors: Aimin
authors: A
authors: Wang
authors: Chun
authors: C
authors: Li
authors: Jie
authors: J
authors: Liao
authors: Min
authors: M
authors: Dong
authors: Zhiming
authors: Z
authors: Xiao
authors: Minxiang
authors: M
authors: Lei
mesh_terms: D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D042783:Endothelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051058:Oncogene Protein v-akt / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors
chemical_list: D002518:Ceramides; D007328:Insulin; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D051058:Oncogene Protein v-akt; D005947:Glucose