Study On The Gene Related To Pheochromocytoma And The Effects Of Inflammatory Stress On LDL Receptor Expression In Liver

PART 1 STUDY ON THE MUTATIONS OF SDHD GENE IN SPORADIC PHEOCHROMOCYTOMA IN CHONGQINGObjective To study the association of SDHD gene mutations and the sporadic pheochromocytoma in ChongqingMethods Polymerase chain reaction combining with single strand conformation polymorphism (PCR-SSCP) was selected to analysis the mutations in the SDHD gene in 33 cases of sporadic pheochromocytoma that were diagnosed by pathology, including 20 cases of peripheral blood samples ,13 cases of tumor samples imedded by paraffin and 80 cases of the healthy controls. Of all cases, 20 cases of peripheral blood samples were detected mutations in all four exons of SDHD gene while 13 cases of tumor samples were only detected in the first and second exons. The abnormal segment was reamplificated and then directly sequenced. Results No mutation was found in SDHD gene in the 33 patients.Conclusion In our study, we had not found any mutation in the SDHD gene in sporadic pheochromocytoma in Chongqing.PART 2 EFFECTS OF INFLAMMATORY STRESS ON LDL RECEPTOR EXPRESSION IN LIVER OF SRA/CD36 DOUBLE KNOCKOUT MICE AND ITS POTENTIAL MECHANISMObjective This work was aimed to investigate the effects of inflammatory stress on low density lipoprotein (LDL) receptor (LDLr) expression in the Liver of scavenger receptor A (SRA)/CD36 double knockout mice and its potential mechanisms.Methods 1～3 months old, male SRA/CD36 knockout mice fed with high lipid diet containing with 15% fatty, 1.25% cholesterol and 0.5% bile acid) were randomly divided into control group(n=7) and inflammation group(n=6). Their weight were 18~23 g. Casein injection was used in inflammation group to induce inflammatory stress. After 14 weeks, both mRNA and protein expressions of LDLr, sterol regulatory element binding protein 2 (SREBP2) and SREBP cleavage-activating protein (SCAP) genes in the liver were examined by real-time fluorescence quantitative reverse transcription polymerase chain reaction and immunohistochemistry staining respectively. Serum levels of total cholesterol (TC), triglyceride (TG), Low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were measured by biochemical techniques. Serum concentration of Serum Amyloid Protein (SAA) was determined by ELISA. Frozen sections of liver were stained with Red Oil O to visualize the lipid accumulation.Results Under inflammatory stress, the expressions of LDLr, SCAP and SREBP2 genes were significantly increased compared with controls(P<0.05). Lipid accumulation in the livers was increased. Serum levels of TC and LDL-C, not TG and HDL-C were significantly lower(P<0.05).Conclusion Inflammatory stress up-regulates the expressions of SREBP2, SCAP and LDLr genes in the liver of SRA/CD36 double knockout mice. This may contribute to the lipid accumulation in the liver.