Background Apelin, a cytokine mainly secreted by adipocytes, shows beneficial effect on insulin resistance. However, the molecular mechanism underlying is still poorly understood. This study was to investigate the mechanisms of apelin on insulin resistant improvement in 3T3-L1 adipocytes.
Methods Insulin resistance in 3T3-L1 adipocytes was induced by TNF-α. The effects of apelin on glucose metabolism were investigated by 3H-2-Deoxy-glucose uptake. The effects of apelin on glucose transporter four translocation were visualised by immunofluorescence microscopy. The role of PI3K/Akt pathway was assessed by immunoblotting. The effects of apelin on interlukin-6 and adiponectin mRNA expression were observed by RT-PCR.
Results Insulin-stimulated glucose uptake could be reduced by 47% by treatment with TNF-α for 24 h. Apelin could improve insulin-stimulated glucose uptake with the involvement of PI3K/Akt pathway. In addition, microscopy imaging showed apelin could increase GLUT4 translocation to plasma membrane. RT-PCR assay indicated apelin also increased adiponectin while reduced interlukin-6 mRNA expression in insulin-resistant adipocytes.
Conclusion This study suggested that apelin stimulates glucose uptake through PI3K/Akt pathway and GLUT4 translocation, while moderate inflammatory responses in insulin-resistant 3T3-L1 adipocytes.