Mechanisms of ß-adrenergic receptors agonists in mediating pro and anti-apoptotic pathways in hyperglycemic Müller cells.

ABSTRACT

BACKGROUND: The current study aimed to investigate the stimulatory effect of beta-adrenergic receptors (ß-ARs) on brain derived neurotropic factor (BDNF) and cAMP response element binding protein (CREB). METHODS: Human Müller cells were cultured in low and high glucose conditions. Cells were treated with xamoterol (selective agonist for ß1-AR), salmeterol (selective agonist for ß2-AR), isoproterenol (ß-ARs agonist) and propranolol (ß-ARs antagonist), at 20 µM concentration for 24 h. Western Blotting assay was performed for the gene expression analysis. DNA damage was evaluated by TUNEL assay. DCFH-DA assay was used to check the level of reactive oxygen species (ROS). Cytochrome C release was measured by ELISA. RESULTS: Xamoterol, salmeterol and isoproterenol showed no effect on Caspase-8 but it reduced the apoptosis and increased the expression of BDNF in Müller cells. A significant change in the expression of caspase-3 was observed in cells treated with xamoterol and salmeterol as compared to isoproterenol. Xamoterol, salmeterol and isoproterenol significantly decreased the reactive oxygen species (ROS) when treated for 24 hours. Glucose-induced cytochrome c release was disrupted in Müller cells. CONCLUSION: ß-ARs, stimulated by agonist play a protective role in hyperglycemic Müller cells, with the suppression of glucose-induced caspase-3 and cytochrome c release. B-Ars may directly mediate the gene expression of BDNF.