ABSTRACT
ObjectiveTo investigate the effect and mechanism of total saponins from Panax japonicus （TSPJ） on white adipose tissue （WAT） browning/brown adipose tissue （BAT） activation in C57BL6/J male mice fed on a high-fat diet （HFD）. MethodThirty-two C57BL6/J male mice （8-week-old） were randomly divided into a normal group， a model group， a low-dose TSPJ group， and a high-dose TSPJ group. The mice in the low-dose and high-dose TSPJ groups were given TSPJ for four months by gavage at 25， 75 mg·kg-1·d-1， respectively， and those in the other groups were given 0.5% sodium carboxymethyl cellulose （CMC-Na） accordingly. After four months of feeding， all mice were placed at 4 ℃ for acute cold exposure， and the core body temperature was monitored. Subsequently， all mice were sacrificed， and BAT and inguinal WAT （iWAT） were separated rapidly to detect the corresponding indexes. Hematoxylin-eosin （HE） staining was used to observe the morphological changes in each group. The effect of TSPJ on the mRNA expression of uncoupling protein 1 （UCP1）， fatty acid-binding protein 4 （FABP4）， cytochrome C （CytC）， PR domain-containing protein 16 （PRDM16）， elongation of very long chain fatty acids protein 3 （ELOVL3）， peroxisome proliferator-activated receptor γ （PPARγ）， and peroxisome proliferator-activated receptor-γ coactivator-1α （PGC-1α） in iWAT and BAT was detected by Real-time polymerase chain reaction （Real-time PCR）. Western blot was also used to detect the protein expression of UCP1， PRDM16， PPARγ， and PGC-1α in BAT and iWAT of each group. The effect of TSPJ on UCP1 expression in BAT and iWAT was detected by immunohistochemistry. Result① Compared with the model group， TSPJ could decrease the body weight and proportions of iWAT and BAT in the HFD-induced mice （P<0.05， P<0.01）. ② The body temperature of mice in the model group decreased compared with that in the normal group in the acute cold exposure tolerance test （P<0.05）. The body temperature in the high-dose TSPJ group increased compared with that in the model group （P<0.01）. ③ Compared with the normal group， the model group showed increased adipocyte diameter in iWAT and BAT and decreased number of adipocytes per unit area. Compared with the model group， the TSPJ groups showed significantly reduced cell diameter and increased number of cells per unit area， especially in the high-dose TSPJ group. ④ Compared with the normal group， the model group showed decreased mRNA expression of FABP4， UCP1， CytC， PRDM16， ELOVL3， PGC-1α， and PPARγ in adipose tissues of mice （P<0.05， P<0.01）. Compared with the model group， after intervention with TSPJ， the mRNA expression was significantly up-regulated （P<0.05， P<0.01）. ⑤ Compared with the normal group， the model group showed decreased protein expression of UCP1， PRDM16， PPARγ， and PGC-1α in adipose tissues of mice （P<0.05， P<0.01）. Compared with the model group， after intervention with TSPJ， the protein expression increased significantly （P<0.05， P<0.01）. ConclusionTSPJ could induce the browning of iWAT/BAT activation and enhance adaptive thermogenesis in obese mice induced by HFD. The underlying mechanism may be attributed to the activation of the PPARγ/PGC-1α signaling pathway.
ABSTRACT
Objective:To investigate whether long non-coding RNA(lncRNA) AW112010 can improve insulin resistance in aging adipocytes through the miR-204/POU2F2 signaling pathway.Methods:In vivo experiment: C57BL/6 mice were divided into young control group(4 months old) and aging model group(18 months old) based on body weight. The expression levels of AW112010, miR-204-5p, POU2F2, aging related indicators(p16, p21), and insulin signaling pathway genes [insulin receptor(INSR), insulin receptor substrate 1(IRS1), phosphatidylinositol kinase(PI3K), protein kinase B(AKT)] in epididymal adipose tissue were detected using real-time fluorescence quantitative PCR(RT-qPCR) and Western blotting. In vitro experiment: Using adriamycin(ADR) to induce 3T3-L1 aging adipocyte model, β-gal staining was used to observe cellular senescence, and miR-204 inhibitor and miR-204 mimic small interfering RNA were successfully constructed and transfected into 3T3-L1 adipocytes. Results:RT-qPCR and Western blot results showed that compared with the young group, the expression of AW112010 in the adipose tissue of aging mice was increased, while the expression of miR-204-5p was decreased. The expressions of POU2F2, p16, and p21 in the adipose tissue of aging mice were increased, while the expressions of INSR, IRS1, PI3K, GLUT4 mRNA and protein were decreased. The β-gal stainging results showed that the number of 3T3-L1 senescent adipocytes induced by ADR was significantly increased, and the expression levels of AW112010, POU2F2, p16, and p21 in ADR-induced senescent adipocytes were increased compared with the control group, while the expression levels of miR-204-5p, INSR, IRS1, PI3K, GLUT4 were decreased, and remaining glucose in the culture medium was increased. Compared with control, overexpression of miR-204 resulted in decreased expressions of aging indicators p16, p21, and target gene POU2F2 while the expressions of INSR and GLUT4 were increased.Conclusion:Upregulation of lncRNA AW112010 in adipocytes of aging mice may induce insulin resistance by targeting miR-204-5p/POU2F2/IRS1.