High glucose condition down-regulates the inhibitory G-protein subunit, Gαi, in pheochromocytoma PC12 cells

Introduction: G-proteins have an important role in the cell signaling of numerous receptors. The situation of G-proteins in health and disease and their critical role in the development of diabetic side effects is an interested scientific field. Here, the changes in the expression of G-protein subunits (Gαi, Gαs and Gβ) were evaluated in hyperglycemic situation of PC12 cells as a cellular model for the induction of diabetic side effect. Methods: Rat pheochromocytoma PC12 cells were grown in normal or high-glucose (4X normal glucose) medium. Cell viability was determined by MTT assay and the generation of intracellular reactive oxygen species (ROS) studied using fluorescence spectrophotometry. RT-PCR and immunobloting were performed to evaluate the expression of specific G-protein subunits in the levels of mRNA and protein, respectively. Results: In high glucose condition (100 mM glucose for 48h), the cell viability was significantly decreased and intracellular ROS increased. In addition, Gαi expression level was significantly decreased in hyperglycemic PC12 cells. However, the levels of Gαs and Gβ mRNAs and their proteins were not altered in high glucose-treated cells. Conclusion: The results demonstrate that deregulation or disruption in the signaling of Gai coupled receptors can be occurred in hyperglycemic condition.