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Background: The aim of the present study was to investigate whether histamine induces up-regulated expression of uncoupling protein 2 (UCP2) and fat acid-binding protein (aP2) in white adipocytes (differentiated 3T3-L1 cells). Methods: Differentiation of 3T3-L1 preadipocytes to adipocytes was induced by the addition of 5 μg/mL insulin, 1 μmol/L dexamethasone, 10 mmol/L 1-isobutyl-3-methylxanthine, 1% dimethylsulfoxide, and 10% fetal bovine serum in Dulbecco's modification of Eagle's medium. Total RNA from differentiated 3T3-L1 cells was extracted and semi-quantitative RT-PCR was performed to determine the levels of UCP2 and aP2 mRNA. The expression level of UCP2 protein was determined by Western blot analysis. Results: Histamine at a concentration of 30 μmol/L significantly increased the expression of UCP2 mRNA and UCP2 protein, and expression levels reached a peak value. There were significant differences in the expression levels of UCP2 mRNA and UCP2 protein in adipocytes treated with 30 μmol/L histamine at various time points within 48 h, and their levels reached a peak value after 6 h of incubation. In addition, histamine increased the expression level of aP2 mRNA in adipocytes. Expression of aP2 mRNA in adipocytes reached the highest value at a concentration of 20 μmol/L histamine after 6-h incubation. Finally, we found that diphenhydramine (a H1 receptor antagonist) significantly decreased expression levels of UCP2 mRNA and protein, as well as aP2 mRNA. There were significant differences in expression levels of UCP2 and aP2 mRNA in adipocytes treated at concentrations of 20 μmol/L histamine and diphenhydramine, respectively. Conclusions: These data reveal that histamine up-regulated the expression of UCP2 and aP2 in vitro in white adipocytes. Clin Chem Lab Med 2007;45:1199–206. [ABSTRACT FROM AUTHOR]

Background: Genetic polymorphisms of β3-adrenergic receptor (AR) Trp64Arg and β2-AR Gln27Glu may result in significant change in the functions of these receptors. The aims of the present study were to investigate the association between Trp64Arg, Arg16Gly and Gln27Glu polymorphisms and the susceptibility to obesity and hypertension in a Chinese population. Methods: A total of 437 Chinese subjects including 149 obese hypertensive patients, 139 non-obese essential hypertensive patients, and 149 non-obese normotensive healthy controls were enrolled in the study. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and allele-specific (AS)-PCR assays were used to identify Trp64Arg, Arg16Gly, and Gln27Glu genotypes. Results: The allele frequencies of 64Arg and 27Glu in the obese hypertensive group were 0.178 and 0.128, respectively. Both were significantly higher than in the non-obese hypertensive and the control groups (p<0.05). Further analysis showed that this association existed only in male hypertensive patients. Conclusions: These data reveal that frequencies of β3-AR 64Arg and β2-AR 27Glu were significantly higher in our obese hypertensive patients than in the non-obese hypertensive population and healthy controls. β3-AR Trp64Arg and β2-AR Gln27Glu genetic polymorphisms are associated with obesity in Chinese male hypertensive patients. Clin Chem Lab Med 2007;45:493–8. [ABSTRACT FROM AUTHOR]