Non alkolik yağlı karaciğer hastalığı modelinde oksisterollerin lipit metabolizması ve enoplazmik retikulum stres yolağına etkisi (Doktora Tez projesi)


Şahin A. , Kartal Özer N. (Executive)

Project Supported by Higher Education Institutions, 2015 - 2017

  • Project Type: Project Supported by Higher Education Institutions
  • Begin Date: September 2015
  • End Date: December 2017

Project Abstract

Aim: The aim of this study is to investigate the effect of varying oxysterol levels on liver lipid metabolism and ER stress in NAFLD model of high cholesterol diet, and the role of vitamin E in this process. Material and Methods: 24 male albino rabbits were assigned randomly to 4 groups: 1) Control; normal rabbit chow 2) Cholesterol; 2% cholesterol containing chow 3) Cholesterol+Vitamin E; 2% cholesterol food with daily i.m. injections of vitamin E and 4) Vitamin E; normal food + daily i.m. injections of vitamin E. After 8 weeks, blood samples and liver tissues were collected. Liver tissues were examined macroscopically. In sections obtained from high cholesterol fed rabbits liver tissues were photographed NAFL formation with oil red staining and immunohistochemically development of inflammation and steatosis with α-SMA, RAM11, col1A1 and 4HNE markers on a light microscope. Endoplasmic reticulum stress (pIRE1, pPERK, Grp78 and Grp94), lipid metabolism alteration (transcription factor of PPARα, PPARγ, SREBP1 and SREBP2) and oxysterol-related (LXRα and ABCA1) proteins were determined by immunoblotting technique.  Oxysterol levels were measured by LC-MS/MS using the MRM method. Results: Expression of pIRE1 and Grp94 protein significantly increased in the hypercholesterolemic group, but significantly decreased in the cholesterol + vitamin E group. While SREBP1, SREBP2 and PPARγ expressions were increased in cholesterol group, these proteins were significantly decreased in cholesterol + vitamin E group. LXRα decreased in cholesterol group but ABCA1 was not change. While vitamin E administration was further decreasing LXRα, ABCA1 expression significantly increased. Oxysterols; 24(S)-OHC, 25-OHC and 7-KC increased in cholesterol group, but no change were found for 27-OHC and 7α-OHC. While 24(S)-OHC, 25-OHC and 7-KC were significantly decreased with vitamin E supplementation, 27-OHC and 7α-OHC were significantly increased. Conclusion: Our results suggest that NAFLD develped in high cholesterol fed rabbits by increased accumulation of lipids in the liver, thus affects oxysterol levels, and that varying levels of oxysterols play a role in triggering ER stress, and vitamin E administration is thought to play a role in reducing NAFLD development in this process.

Key Words: Non-alcoholic fatty liver disease, oxysterol, ER stress