The Effects And Machanism Of Cholesterol Overload On Visfatin Secretion From Adipocytes

Objectives:The objective of the study was to observe the effect of cholesterol overload on visfatin secretion from adipocytes and investigate the potential machanism. Methods:3T3-L1 adipocytes were cultured and differentiated into mature adipocytes in vitro. Their morphology change was observed through microscope and oil red O stain was taken to identify the adipocytes. The adipocytes were intervened by ACAT inhibitor (2ul) and ox-LDL with various concentrations (0,25,50,75,100ug/ml) for 48 hours, ACAT inhibitor (2ul) and ox-LDL (50ug/ml) at the 0,6th,18th,36th and 48th hour, or ACAT inhibitor (2ul), ox-LDL (50ug/ml) and TUDCA with various concentrations (0,100,200,400 uM) for 48 hours. The levels of visfatin in supernatant were examined by ELISA and the expressions of protein GRP78 and CHOP in adipocytes were detected by Western Blot. Results:1. After the adipocytes were treated with ACAT inhibitor and ox-LDL at different concentrations for 48 hours, the cholesterol concentration in adipocytes was upregulate with the increase of the ox-LDL concentration in a dose-dependent manner. Compared with control group(ox-LDL Oug/ml), the cholesterol concentrations in adipocytes of the other groups were higher and the differences had statistical significance (all P<0.05).2. After the adipocytes were treated with ACAT inhibitor and ox-LDL at different concentrations for 48 hours, the expressions of GRP78 and CHOP protein in adipocytes and the visfatin levels in the supernatant fluid were increased with the increase of the ox-LDL concentration. The differences had statistical significance in the other groups compared with control group(ox-LDL Oug/ml) (all P<0.05).3. After the intervention with ACAT inhibitor and ox-LDL for different time, the expressions of GRP78 and CHOP protein in adipocytes and the visfatin levels in the supernatant fluid were upregulated in a time-dependent manner. The differences had statistical significance in the other groups compared with control group(for Oh) (all P<0.05).4. After the intervention with ACAT inhibitor, ox-LDL and different concentrations of TUDCA for 48 hours, the expressions of GRP78 and CHOP protein in adipocytes and visfatin levels in the supernatant fluid were down-regulated in a time-dependent manner and compared with control group(TUDCA OuM) the difference were statistical significance (all P<0.05). Conclusions:1. The intervention of ACAT inhibitor and ox-LDL can cause the cholesterol overload in adipocytes. 2. The cholesterol overload can promote the visfatin secretion from adipocytes in a dose and time-dependent manner.3. It may involve the enhanced endoplasmic reticulum stress that the cholesterol overload upregulates the visfatin secretion from adipocytes.