Osteopontin-induced brown adipogenesis from white preadipocytes through a PI3K-AKT dependent signaling.

Recent studies have shown that OPN (osteopontin) plays critical roles in cell survival, differentiation, bio-mineralization, cancer and cardiovascular remodeling. However, its roles in the differentiation of brown adipocytes and the underlying mechanisms remain unclear. Therefore, the aim of this study was to investigate the roles of OPN in the brown adipogenesis and the underlying mechanisms. It was shown that the OPN successfully induced the differentiation of 3T3-L1 white preadipocytes into the PRDM16(+) (PRD1-BF1-RIZ1 homologous domain containing 16) and UCP-1(+) (uncoupling protein-1) brown adipocytes in a concentration and time-dependent manner. Also, activation of PI3K (phosphatidylinositol 3-kinase)-AKT pathway was required for the OPN-induced brown adipogenesis. The findings suggest OPN plays an important role in promoting the differentiation of the brown adipocytes and might provide a potential novel therapeutic approach for the treatment of obesity and related disorders.

[Effects of electroacupuncture on sexual development and ovarian estrogen receptor ß expression in female adolescent obese rats].

OBJECTIVE: To observe the effect of electroacupuncture on sexual development and ovarian estrogen receptor ß(ER-ß) expression in female adolescent obese rats induced by high-fat diet, so as to explore its underlying mechanisms of improving adolescent obesity. METHODS: Female SD rats (age of 21 days) were randomly divided into control, model and acupuncture groups, with 6 rats in each group. The obese model was established by feeding high-fat diet for 6 weeks. Rats of the acupuncture group received electroacupuncture(2 Hz, 0.5-1.2 mA)stimulation at bilateral "Sanyinjiao"(SP6), "Fenglong"(ST40) and "Zusanli"(ST36) for 30 min, once a day for 14 days. The body mass and abdominal circumference of rats were measured before and after treatment. The contents of serum follicle stimulating hormone (FSH), luteinizing hormone (LH) and estradiol (E2) were detected by ELISA. The number of corpus luteum and follicle were observed by HE staining. The expression levels of ER-ß mRNA and protein in ovary were detected by fluorescence quantitative PCR and Western blot, respectively. RESULTS: Compared with the control group, the body mass and abdominal circumference, the contents of serum FSH and E2, and the expression levels of ER-ß mRNA and protein in ovary were significantly increased (P<0.05)in the model group, while the number of mature follicles and corpus luteum increased significantly. Compared with the model group, the body mass and abdominal circumference, the contents of serum FSH and E2, and the expression levels of ER-ß mRNA and protein in ovary were significantly decreased (P<0.05) in the acupuncture group, while the number of mature follicles and corpus luteum decreased significantly. CONCLUSION: Electroacupuncture can effectively improve the levels of sex hormone and the development of ovary, down-regulate the expression levels of ER-ß mRNA and protein in ovary, so as to regulate the process of sexual development of female adolescent obese rats induced by high-fat diet.

Pharmacological activation of PPAR gamma ameliorates vascular endothelial insulin resistance via a non-canonical PPAR gamma-dependent nuclear factor-kappa B trans-repression pathway.

Vascular endothelial insulin resistance (IR) is a critically initial factor in cardiocerebrovascular events resulted from diabetes and is becoming a worldwide public health issue. Thiazolidinediones (TZDs) are clinical insulin-sensitizers acting through a canonical peroxisome proliferator-activated receptor gamma (PPARγ)-dependent insulin trans-activation pathway. However, it remains elusive whether there are other mechanisms. In current study, we investigated whether TZDs improve endothelial IR induced by high glucose concentration or hyperglycemia via a non-canonical PPARγ-dependent nuclear factor-kappa B (NF-κB) trans-repression pathway. Our results showed that pre-treatment with TZDs dramatically decrease the susceptibility of endothelial cell to IR, while post-treatment notably improve the endothelial IR both in vitro and in vivo. Moreover, TZDs substantially increase the levels of endothelial nitric oxide synthase (eNOS) and inhibitory κB alpha (IκBα), whereas decrease those of the phosphorylated inhibitory κB kinase alpha/beta (phosphor-IKKα/ß) and the cytokines including tumor necrosis factor alpha (TNFα), interleukin-6 (IL-6), soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cellular adhesion molecule-1 (sVCAM-1), suggesting that TZDs act indeed through a PPARγ-dependent NF-κB trans-repression pathway. These findings highlighted a non-canonical mechanism for TZDs to ameliorate endothelial IR which might provide a potential strategy to prevent and treat the diabetic vascular complications clinically.