Investigation effects of pterostilbene on differentiation and adipogenesis in 3T3-L1 cells

Diabetes mellitus (DM) is a chronic illness that occurs when there is inadequate insulin secretion and/or insulin action defect. DM is usually characterized by high blood sugar (hyperglycemia) above normal blood sugar levels. Having consistently high blood glucose causes general vascular damage that affects the kidneys, nerves, heart, eye vessels and can lead to a variety of health problems. In etiology, diabetes is divided into three main groups as gestational diabetes (GDM), type 1 diabetes and type 2 diabetes. Plant extracts are very important sources in the search for alternative new drug active ingredients. Pterostilbene is known as a naturally dimethylated analogue of resveratrol and its main source is grapes and blueberries. In this study, it was aimed to evaluate the effects of Pterostilbene on differentiation and adipogenesis in 3T3-L1 cells. For this purpose, Pterostilbene was treated to mature 3T3-L1 adipocytes at different concentrations and half-maximum inhibitory concentrations (IC50) were determined by MTT. Based on the results, 5 and 7.5 µM doses of Pterostilbene were chosen to apply to cells in subsequent experiments. In addition, Oil Red O was applied to determine the lipid accumulation and effects of Pterostilbene in preadipocytes and 3T3-L1 adipocytes, and it was observed that Pterostilbene treatment reduced lipid accumulation in adipocyte differentiation. The cytotoxic effect of Pterostilbene in 3T3-L1 adipocyte cells was confirmed by dead/live cell assay. Phase contrast microscopy and Giemsa staining, F-actin staining and DAPI staining were applied to investigate the effect of Pterostilbene on the morphology of 3T3-L1 adipocyte cells. According to the study result, adipocytes treated with a dose of 7.5 µM on day 14 showed less intense lipid deposition and a more spindle-like morphology compared to the other treatment group. Finally, the expression of Glucose transporter-4 (Glut-4) and Adinopectin associated with insulin resistance was evaluated by immunofluorescent staining and qRT-PCR. Especially on the 14th day, compared to the other treatment group, actin filaments were filamentous in adipocytes treated with Pterostilbene 7.5 µM compared to the other treatment group, the filaments were similarly oriented as in preadipocytes, and chromatin condensation was observed to be quite high. As a result of this study, it was observed that Pterostilbene induce apoptosis, reduce lipid accumulation but induce Glut-4 and Adiponectin level, and may conduce to the reduction of insulin resistance in diabetes. Keywords: Diabetes mellitus, Pterostilbene, 3T3-L1, Adipogenesis, Differentiation, Glucose transporter 4, Adiponectin.