| Excessive energy intake is stored in adipose tissue as fat. However, overloaded fat in adipose tissue that spills into other tissues can cause various chronic diseases including insulin resistance, a precursor of obesity-induced type 2 diabetes (T2DM). Therefore, expanding the capacity of adipose tissue to form healthy new adipocytes for storing fat would be a critical strategy to improve insulin sensitivity. Peroxisome proliferator-activated receptor gamma (PPARgamma), is a highly expressed nuclear receptor found in adipocytes, and plays an important role in adipogenesis by inducing the differentiation of preadipocytes into adipocytes, allowing the formation of new adipocytes. In practice, thiazolidinediones, (TZDs) a class of drugs used to treat T2DM, behave as ligands that stimulate the expression of PPARgamma. However, use of TZDs presents adverse side effects, such as edema and liver damage. Therefore, many natural products with PPARgamma agonist activity have gained attraction as an alternative remedy of obesity-induced T2DM. Cinnamon (cinnamonum cassia) has been used extensively as a traditional herb to manage numerous health conditions. In this study our aim was to investigate the effects of cinnamon extract on different stages of differentiation using 3T3-L1 cells. Briefly, 3T3-L1 cells were cultured and differentiated into mature white adipocytes for 11 days. To determine the effect of cinnamon extract on the different stages of differentiation, 3T3-L1 cells were treated with 50, 100, and 200 mug/ml cinnamon extract at the preadipocyte (day 1), induction of differentiation (day 3), and progress of differentiation (days 5, 7, and 9) stages. On day 11, total RNA was extracted from the cells and to synthesize cDNA, a template for polymerase chain reaction (PCR). Real-time PCR was used to quantify the expression of PPARgamma, acetyl CoA carboxylase (ACC), fatty acid synthase (FAS), carnitine palmitoyltransferase 1alpha (CPT1alpha), PPARalpha, and PPARgamma coactivator 1alpha (PGC1alpha) genes. To determine lipid accumulation by cinnamon extract treatment, mature adipocytes were stained with Oil Red O staining. Statistical analysis was performed using one-way ANOVA with Tukey's post-hoc test. Results show that gene expression of PPARgamma and FAS was increased by day 1 and day 3 treatment of cinnamon extract, however, images from Oil Red O staining showed that there was no significant change in lipid accumulation within the mature adipocytes. Expression of CPT1alpha, PPARalpha, and PGC1alpha genes was increased by day 1 and day 5, 7, and 9 treatment, indicating that cinnamon extract may improve adipocyte metabolism by increasing mitochondrial fatty acid beta-oxidation during differentiation. Taken together, these results suggest that cinnamon extract behaves as a PPARgamma agonist and may effectively increase the lipid storage capacity of white adipocytes at the earlier stages of differentiation. This may lead to improved insulin sensitivity and potentially serve as an alternative remedy for managing obesity-induced T2DM. |
