Differential Proteomics Analysis Of Adipose Tissue From Xiang Pigs Treated With Clenbuterol

Proteomics provides a complementary and potentially more comprehensive approach to the analysis of signaling mechanisms. Changes in protein profiles during signaling events can be monitored using two-dimensional (2D) gel electrophoresis or related techniques, detecting alterations in expression levels. Clenbuterol is often illegally used in zootechnics because it affect the protein/lipid metabolism, thus favouring muscle enlargement and body fatty deposit reduction. As a β 2 AR agonist, clenbuterol is a very good repartitioning agent which cause a reduction of adipose deposits and an increase in muscle mass. Many studies have been undertaken to determine the mechanism of its action even though its use is prohibited. It is known that clenbuterol influence lipid metabolism through cAMP signaling and phosphorylation of key enzymes in lipid metabolism. However, the regulation of lipid metabolism is a complex process, and many specific mechanisms involved are not yet fully understood through administration of clenbuterol.Objectives of this study were to identify proteins differentially expressed in adipose tissue after administration of clenbuterol using two dimensional electrophoresis combined with mass spectrometry to further our understanding of the action mechanism of clenbuterol on adipose tissue.We construct and modified the two dimensional electrophoresis method for proteins extracted from adipose tissue. For sample preparation, the adipose tissue sample was grounded in liquid nitrogen and then homogenized in the lysis buffer (8M urea, 2M thiourea, 50mM DTT, 0.5% carrier amphorlyte and 1mM PMSF), then centrifuged at 15 000 rpm for 1 h at room temperature, the soluble infranatant, below the fat supernatant, was carefully recovered, avoiding the unhomogenized material at the bottom of the centrifuge tube. For the preparative gel staining, we tried the "blue silver" method to improve the resolution of the two dimensional electrophoresis map.Using two dimensional electrophoresis and Peptide Mass Fingerprint (PMF) analysis, the differential expressed protein: apolipotrotein R was identified. It implyed that apolipotrotein R may be involved in the lipolysis stimulation of clenbuterol. Considering that the clenbuterol can increase blood flow, we concluded that the Apo R may be involved in the action of clenbuterol through binding the nonesterifled fatty acids away from the adipose tissue to enhance the lipid degradation process.