Effects of Glucose Concentration on Differentiation, Adipogenic Marker Genes Expression and Glucose Transporter Distribution in Bovine Subcutaneous Preadipocytes

Background: Fat deposition in beef cattle significantly influences both the meat yield of individual carcasses and the perceived eating quality for consumers. Glucose, as a crucial regulator, plays an essential role in the differentiation of bovine preadipocytes and lipid metabolism. This study aimed to investigate the effects of varying glucose concentrations (0, 3.0, 3.5 and 4.0 mmol/L) on the differentiation of bovine subcutaneous preadipocytes. Additionally, we explored the expression levels of key adipogenic marker genes and the distribution of glucose transporters during adipocyte differentiation. Methods: The differentiation of preadipocytes was assessed using Oil Red O staining and triacylglycerol content was quantified using a triglyceride assay kit. To evaluate the expression of adipogenic genes included peroxisome proliferator-activated receptor- γ (PPARγ), fatty acid synthase (FAS) and acetyl-CoA carboxylase 1 (ACC1), quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure mRNA levels, while protein levels were determined through western blotting. Additionally, the distribution of glucose transporters GLUT1 and GLUT4 during differentiation was analyzed through immunofluorescence. Result: The results showed that the differentiation of preadipocytes, along with the accumulation of lipid droplets, was enhanced at 2 and 4 days (p less than 0.05). However, this effect gradually diminished by day 8 as glucose concentration increased. During the early stages of preadipocyte differentiation, the expression of adipogenic marker genes-PPARγ, FASand ACC1-significantly increased at both the mRNA and protein levels (p less than 0.05, p less than 0.01). However, by day 8, as glucose concentration increased, a decreasing trend in the expression of these genes was observed. The fluorescence intensity of glucose transporters GLUT1 and GLUT4 rose significantly with higher glucose concentrations. These findings suggested that adding glucose at 3.0 to 3.5 mmol/L to the differentiation medium is optimal for promoting differentiation and fat deposition in bovine subcutaneous preadipocytes.