Role of beta-adrenergic receptors in inflammatory marker expression in Müller cells.
OBJECTIVE
To determine whether beta-adrenergic receptors are involved in the modulation of inflammatory cytokines in Müller cells in a hyperglycemic environment.


METHODS
Rat Müller cells were grown in high (25 mM)- or low (5 mM)-glucose medium. Müller cells lysates were processed for real-time polymerase chain reaction to measure steady state mRNA expression for the following inflammatory markers: iNOS, TNF-alpha, IL-1B, and ICAM-1. Western blot analysis and ELISA assays were performed to determine the protein levels of these inflammatory markers and PGE2 content.


RESULTS
Isoproterenol treatment significantly decreased protein levels of iNOS, TNF-alpha, and IL-1B, in rMC-1 cells cultured in high glucose as early as 1 hour, compared with cells receiving no treatment. PGE2 content was also reduced after isoproterenol treatment. There were no significant changes observed in protein levels of ICAM-1 production after isoproterenol treatment in high glucose. Steady state mRNA levels for iNOS were significantly decreased 1 hour after isoproterenol, whereas ICAM-1 gene expression was significantly increased after 1 hour. Isoproterenol significantly increased gene expression for IL-1B after 24 hours of treatment.


CONCLUSIONS
These results suggest that stimulation of beta-adrenergic receptors with isoproterenol leads to decreased levels of PGE(2), TNF-alpha, and IL-1B protein content, and in both gene expression and protein levels of iNOS in Müller cells cultured in hyperglycemia. beta-Adrenergic receptor agonists had limited effects on ICAM-1 protein production. These results indicate that isoproterenol treatment reduces cytokine activation in cultured rat Müller cells.
Walker
Robert J
RJ
Department of Physiology, Southern Illinois University School of Medicine, Carbondale, IL, USA.
Steinle
Jena J
JJ
D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D015153:Blotting, Western; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D018836:Inflammation Mediators / Q000378:metabolism*; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis / Q000235:genetics; D053583:Interleukin-1beta / Q000096:biosynthesis / Q000235:genetics; D007545:Isoproterenol / Q000494:pharmacology; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D018342:Receptors, Adrenergic, beta-1 / Q000378:metabolism*; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D012160:Retina / Q000166:cytology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics
D015415:Biomarkers; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D012333:RNA, Messenger; D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D007545:Isoproterenol