Rubus suavissimus S. Lee extract increases early adipogenesis in 3T3-L1 preadipocytes

Leaves of Rubus suavissimus S. Lee (Rosaceae) are used to prepare tiencha or sweet tea, which is helpful for body weight control by restricting calorie intake in obese patients. Obesity is a risk factor for metabolic syndrome, and a possible approach to treatment is to promote early adipogenesis in adipose tissue, thereby leading to replacement of enlarged adipocytes that secrete inflammatory factors with small adipocytes.We therefore investigated the effect of extract of tiencha leaves on early adipogenesis by using 3T3-L1 preadipocytes as a model. Tiencha extract significantly and concentration-dependently increased adipogenesis measured in terms of lipid accumulation by means of Oil Red O assay and increased the expression of adiponectin and leptin. In the early phase of adipogenesis, tiencha extract increased the mRNA expression of adipogenic transcription factors CCAAT/enhancer binding protein α (C/EBPα) and proliferator-activated receptor γ (PPARγ). In contrast, mRNA expression of other adipogenic transcription factors, C/EBPδ and C/EBPβ, was unaffected. The mRNA expression levels of adipocyte-specific genes encoding adipocyte protein 2 (aP2), lipoprotein lipase (LPL), and glucose transporter 4 (Glut4), which are regulated by C/EBPα and PPARγ, were also increased. A PPARγ inhibitor, GW9662, partially inhibited the enhancing effect of tiencha extract on lipogenesis. These results suggest that tiencha extract enhances early adipogenesis by increasing the expression of adipogenic transcription factors C/EBPα and PPARγ.