The calcium-sensing receptor promotes adipocyte differentiation and adipogenesis through PPARγ pathway.

Adipocyte differentiation and adipogenesis are closely related to obesity and obesity-induced metabolic disorders. The calcium-sensing receptor (CaSR) has been reported to play an antilipolytic role in human adipocyte and regulate cell differentiation in many tissues. However, the effects of CaSR on adipocyte differentiation and adipogenesis have not been clarified. In the study, we observed that activation of CaSR significantly promoted adipocyte differentiation and adipogenesis in human SW872 adipocytes. Gene expression analysis revealed that the CaSR activation increased the transcription factor proliferator-activated receptor γ (PPARγ) and its downstream genes including CCAAT element binding protein α (C/EBPα), adipose fatty acid-binding protein (aP2), and lipoprotein lipase. The activity of glycerol-3-phosphate dehydrogenase was also increased after the stimulation of CaSR. In addition, levels of cyclic AMP and calcium which have been shown to regulate PPARγ gene expression were significantly affected by the activation of CaSR. These effects could be suppressed by CaSR small interfering RNA (CaSR-siRNA). In conclusion, our findings suggest that activation of CaSR promotes differentiation and adipogenesis in adipocytes, which might be achieved by upregulating PPARγ and its downstream gene expressions. Therefore, CaSR in adipocytes may be involved in the pathogenesis of obesity by promoting adipocyte differentiation and adipogenesis.

Histidine and arginine are associated with inflammation and oxidative stress in obese women.

The aims of the present study were to examine the serum amino acid profiles in obese and non-obese women and investigate the relationships between the serum amino acids and inflammation and oxidative stress in a human case-control study. Serum amino acids, inflammatory biomarkers (C-reactive protein and IL-6) and oxidative biomarkers (superoxide dismutase, malondialdehyde and glutathione peroxidase) were measured and compared in 235 obese women and 217 non-obese controls. The relationships between serum amino acids and inflammatory and oxidative biomarkers were examined using multiple linear regression. Among the amino acids determined, serum histidine, arginine, threonine, glycine, lysine and serine were found to be significantly lower in obese women as compared to non-obese controls (P < 0·001). The difference was the greatest for histidine (P < 0·001). In obese women, both histidine and arginine were negatively associated with inflammation and oxidative stress. In non-obese controls, histidine was negatively associated with oxidative stress. The findings in this study indicate that the metabolism of amino acids is abnormal in obese women in whom histidine and arginine have close relationships with inflammation and oxidative stress.

BMI is strongly associated with hypertension, and waist circumference is strongly associated with type 2 diabetes and dyslipidemia, in northern Chinese adults.

BACKGROUND: Obesity is closely associated with chronic diseases such as hypertension, type 2 diabetes mellitus (T2DM), and dyslipidemia. We analyzed the optimal obesity index cut-off values for metabolic syndrome (MetS), and identified the obesity index that is more closely associated with these chronic diseases, in a population of northern Chinese. METHODS: We surveyed 8940 adults (age, 20-74 years) living in northern China for chronic diseases. Receiver operating characteristics (ROC) analysis, relative risk, and multivariate regression were used to develop an appropriate index and optimal cut-off values for MetS and obesity-related chronic diseases. RESULTS: Waist circumference (WC) and body mass index (BMI) were good markers for MetS, WC was a good marker for T2DM and dyslipidemia, and BMI was a good marker for hypertension. The optimal BMI cut-off value of MetS was 24 kg/m², and the optimal WC cut-offs were 86 cm and 78 cm in men and women, respectively. Relative risk regression models showed that BMI was associated with hypertension, T2DM, and hypertriglyceridemia and a higher prevalence ratio (PR) for hypertension: 2.35 (95% CI, 2.18-2.50). WC was associated with T2DM, hypertension, and hypertriglyceridemia, with PRs of 2.05 (1.63-2.55) for T2DM and 2.47 (2.04-2.85) for hypertriglyceridemia. In multivariate regression models, the standardized regression coefficients (SRCs) of BMI were greater for SBP and DBP, and the SRC of WC was greater for fasting blood glucose, 2-hour postload blood glucose, triglyceride, and total cholesterol. CONCLUSIONS: Our analysis of a population of northern Chinese indicates that the optimal cut-off values for MetS are WCs of 86 cm in men and 78 cm in women and a BMI of 24 kg/m² in both sexes. BMI was strongly associated with hypertension, while WC was strongly associated with T2DM and dyslipidemia.

[Effects of chromium and fish oil on the level of leptin and insulin in obese rats].

OBJECTIVE: In order to study the effects of chromium and fish oil on the level of leptin and insulin in obese rats, 32 obese model rats were divided randomly into four groups: fish oil group (5 ml/kg bw), chromium group (3 mg/kg bw), fish oil + chromium group and high fat diet group. METHODS: In the end of the experiment (6 weeks) fats around kidney and spermary were weighted and blood samples were collected to determine the level leptin and insulin. RESULTS: The results showed that the level of leptin and insulin in experimental groups were lower than those in high fat diet group. The ratios of fats around kidney and/or around spermary to body weight in experimental groups were lower than those in high fat diet group. CONCLUSION: Chromium and fish oil possible depress the high level of leptin and insulin in obese model rats.