Role of the adrenergic system in a mouse model of oxygen-induced retinopathy: antiangiogenic effects of beta-adrenoreceptor blockade.
OBJECTIVE
Oxygen-induced retinopathy (OIR) is a model for human retinopathy of prematurity (ROP). In OIR mice, this study determined whether blockade of β-adrenergic receptors (β-ARs) with propranolol influences retinal levels of proangiogenic factors, retinal vascularization, and blood-retinal barrier (BRB) breakdown.


METHODS
Propranolol was administered subcutaneously and picropodophyllin (PPP) intraperitoneally. Intravitreal injections of vascular endothelial growth factor (VEGF) were performed. Messengers of β-ARs, VEGF, its receptors, IGF-1 and IGF-1R were measured with quantitative RT-PCR. VEGF content was determined with ELISA. β-ARs, hypoxia-inducible factor (HIF)-1α, occludin, and albumin were measured with Western blot. Retinal localization of β3-ARs was determined by immunohistochemistry. Retinopathy was assessed by scoring fluorescein-perfused retinas, and plasma extravasation was visualized by Evans blue dye.


RESULTS
Hypoxia did not influence β-AR expression, except that it increased β3-AR protein with dense β3-AR immunoreactivity localized to engorged retinal tufts. Hypoxia upregulated VEGF, IGF-1, their receptors, and HIF-1α. Propranolol dose-dependently reduced upregulated VEGF and decreased hypoxic levels of IGF-1 mRNA and HIF-1α. Blockade of IGF-1R activity with PPP did not influence propranolol's effects on VEGF. Retinal VEGF in normoxic mice or VEGF in brain, lungs, and heart of the OIR mice were unaffected by propranolol. Propranolol ameliorated the retinopathy score, restored occludin and albumin, and reduced hypoxia-induced plasma extravasation without influencing the vascular permeability induced by intravitreal VEGF.


CONCLUSIONS
This is the first demonstration that β-AR blockade is protective against retinal angiogenesis and ameliorates BRB dysfunction in OIR. Although the relevance of these results to infant ROP is uncertain, the findings may help to establish potential pharmacologic targets based on β3-AR pharmacology.
Ristori
Chiara
C
Department of Biology, University of Pisa, Pisa, Italy.
Filippi
Luca
L
Dal Monte
Massimo
M
Martini
Davide
D
Cammalleri
Maurizio
M
Fortunato
Pina
P
la Marca
Giancarlo
G
Fiorini
Patrizio
P
Bagnoli
Paola
P
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn; D001813:Blood-Retinal Barrier / Q000187:drug effects; D015153:Blotting, Western; D002199:Capillary Permeability / Q000187:drug effects; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007231:Infant, Newborn; D007274:Injections, Intraperitoneal; D007279:Injections, Subcutaneous; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism; D058449:Intravitreal Injections; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010100:Oxygen / Q000633:toxicity; D011034:Podophyllotoxin / Q000031:analogs & derivatives / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D017526:Receptor, IGF Type 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D015861:Retinal Neovascularization / Q000378:metabolism / Q000517:prevention & control*; D012178:Retinopathy of Prematurity / Q000378:metabolism / Q000517:prevention & control*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000008:administration & dosage / Q000378:metabolism
D000319:Adrenergic beta-Antagonists; D020533:Angiogenesis Inhibitors; D012333:RNA, Messenger; D011943:Receptors, Adrenergic, beta; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; C415032:picropodophyllin; D007334:Insulin-Like Growth Factor I; D011433:Propranolol; D017526:Receptor, IGF Type 1; D011034:Podophyllotoxin; D010100:Oxygen