Effect of capsaicin on transcription factors in 3T3-L1 cell line

Capsaicin is a spicy ingredient of Capsicum annuum and a lipophilic, crystalline, odorless and colorless alkaloid. Although the effect of capsaicin on adipocyte differentiation is well-known, the role of capsaicin on transcription factors while adipocyte differentiation is not clear. The aim of this study is thus to identify and characterize the transcription factors in the process of adipocyte differentiation after the capsaicin treatment. In this study, concentration of 0, 50, 100, 150, 200 and 250 µM capsaicin were treated to 3T3-L1 pre-adipocytes in cell culture. MTT cell cytotoxicity, cell viability with trypan blue staining, Lactate Dehydrogenase (LDH) enzyme assay, triglyceride content assay, Glycerol-3-Phosphate Dehydrogenase (GPDH) activity, Oil Red O staining and mRNA levels of transcription factors (PPAR?, C/EBP? and SREBP-lc) were investigated in capsaicin induced 3T3-L1 preadipocyte cell line. Capsaicin treatment decreased cell population growth of 3T3-L1 preadipocytes, assessed with trypan blue staining, MTT test and rising of LDH release proportion. Capsaicin inhibited GPDH activity and intracellular triglyceride content in 3T3-L1 adipocytes in all treated groups in a dose-dependent manner. Oil Red O staining indicated that capsaicin inhibited adipocyte differentiation in 3T3-L1 adipocytes in all treatment groups. In this study, it was revealed that exposing 3T3-L1 preadipocytes and differentiating postconfluent preadipocytes to different doses of capsaicin decreased PPAR?, C/EBP? and SREBP-1c mRNA levels as compared with their controls without treatment in dose dependent manner. Although, reduction of PPAR? mRNA level was statistical significant, this decrease was not significant in C/EBP? and SREBP-1c mRNA levels. This study demonstrated that capsaicin treatment inhibited the adipogenesis through the down-regulation of transcription factors, especially PPAR?. Alternative mechanisms may involve cell cycle arrest and the induction of apoptosis. Since capsaicin is the main component found in hot pepper, the consumption of hot pepper may contribute to the maintenance of body weight and prevent the development of obesity.