Morus alba L. Root Bark Stimulates Adipocyte Differentiation in 3T3-L1 Cells

Mori Cortex (MC), the root bark of the mulberry tree (Morus alba L.), has been used traditionally in several Asian countries for medicinal purposes due to its anti-inflammatory, hypoglycemic, and antibacterial activities, as well as its antiviral effects. In the present study, we found that ethanolic extract of Morus alba L. root bark (MC) accelerated differentiation of 3T3-L1 preadipocyte cells. Treatment with MC resulted in enhanced triglyceride (TG) accumulation and increased mRNA levels of C/EBP alpha (CCAAT/enhancer-binding protein alpha) and PPAR gamma (peroxisome proliferator-activated receptors gamma); however, their upstream regulator, C/EBP delta, showed a dose-dependent decrease during adipocyte differentiation. Immunoblot analysis indicated that MC induced an increase in expression of adipogenic maker proteins, such as PPAR gamma, adipocyte-specific fatty acid binding protein 4 (aP2), and GLUT4 (glucose transporter 4). Results of the reporter gene assay revealed that MC did not show PPAR gamma ligand activity even at a high dose (50 mu g/mL), suggesting that enhanced expression of PPAR. resulted not from PPAR gamma ligand activity but by other mechanisms that might be related to the PPAR gamma signal pathway. In conclusion, our findings suggest the potential for use of MC as a possible therapeutic material for treatment of dyslipidemia and type 2 diabetes by increasing PPAR gamma transcriptional activities.