ABSTRACT
Since the functions of Astragalus root extract in retinopathy remain to be unraveled, this study is performed to elucidate whether Astragalus root extract functions in retinal cell apoptosis and angiogenesis in retinopathy of prematurity (ROP). Newborn mice were selected for establishing mice models of oxygen-induced retinopathy (OIR), which were treated with high-, medium- or low-Astragalus root extract. Evans Blue (EB) was perfused to detect the blood retinal barrier. Additionally, the vascular morphology, number of endothelial cell nuclei of neovascularization, proliferation of blood vessels, ultrastructural changes were determined via a series of assays. Moreover, levels of reactive oxygen species (ROS), expression of other factors such as VEGF, PEDF, IGF-1, HIF-1α, Bax, Bcl-2, eNOS, nNOS, and iNOS were detected. Astragalus root extract was found to protect blood-retinal barrier in the OIR model mice through repairing the structure and morphology of retina, inhibiting ROS production, retinal cell apoptosis, as well as improving retinal vascular angiogenesis. Astragalus root extract was also found to decrease VEGF and HIF-1α expression, but enhance PEDF and IGF-1 expression in the OIR model mice, thereby protecting retinas in ROP. This study highlights that Astragalus root extract is able to suppress retinal cell apoptosis and repair damaged retinal neovascularization in ROP, which provides basis for ROP therapy.
Subject(s)
Apoptosis/drug effects , Astragalus Plant/chemistry , Neovascularization, Pathologic/drug therapy , Plant Extracts/therapeutic use , Retina/drug effects , Retinal Vessels , Retinopathy of Prematurity/drug therapy , Retinopathy of Prematurity/metabolism , Animals , Disease Models, Animal , Endothelial Cells/metabolism , Endothelial Cells/ultrastructure , Eye Proteins/genetics , Eye Proteins/metabolism , Hypoxia-Inducible Factor 1, alpha Subunit/genetics , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Insulin-Like Growth Factor I/genetics , Insulin-Like Growth Factor I/metabolism , Mice , Mice, Inbred C57BL , Microscopy, Electron , Neovascularization, Pathologic/metabolism , Nerve Growth Factors/genetics , Nerve Growth Factors/metabolism , Nitric Oxide Synthase Type I/genetics , Nitric Oxide Synthase Type I/metabolism , Nitric Oxide Synthase Type II/genetics , Nitric Oxide Synthase Type II/metabolism , Nitric Oxide Synthase Type III/genetics , Nitric Oxide Synthase Type III/metabolism , Oxygen/toxicity , Plant Extracts/pharmacology , Proto-Oncogene Proteins c-bcl-2/metabolism , Reactive Oxygen Species/metabolism , Retina/cytology , Retina/pathology , Retina/ultrastructure , Retinopathy of Prematurity/chemically induced , Retinopathy of Prematurity/genetics , Serpins/genetics , Serpins/metabolism , Vascular Endothelial Growth Factor A/genetics , Vascular Endothelial Growth Factor A/metabolism , bcl-2-Associated X Protein/metabolismABSTRACT
OBJECTIVE: Pathological ocular neovascularization is a major cause of blindness. Increased dietary intake of ω-3 long-chain polyunsaturated fatty acids (LCPUFA) reduces retinal neovascularization and choroidal neovascularization (CNV), but ω-3 LCPUFA metabolites of a major metabolizing pathway, cytochrome P450 oxidase (CYP) 2C, promote ocular pathological angiogenesis. We hypothesized that inhibition of CYP2C activity will add to the protective effects of ω-3 LCPUFA on neovascular eye diseases. APPROACH AND RESULTS: The mouse models of oxygen-induced retinopathy and laser-induced CNV were used to investigate pathological angiogenesis in the retina and choroid, respectively. The plasma levels of ω-3 LCPUFA metabolites of CYP2C were determined by mass spectroscopy. Aortic ring and choroidal explant sprouting assays were used to investigate the effects of CYP2C inhibition and ω-3 LCPUFA-derived CYP2C metabolic products on angiogenesis ex vivo. We found that inhibition of CYP2C activity by montelukast added to the protective effects of ω-3 LCPUFA on retinal neovascularization and CNV by 30% and 20%, respectively. In CYP2C8-overexpressing mice fed a ω-3 LCPUFA diet, montelukast suppressed retinal neovascularization and CNV by 36% and 39% and reduced the plasma levels of CYP2C8 products. Soluble epoxide hydrolase inhibition, which blocks breakdown and inactivation of CYP2C ω-3 LCPUFA-derived active metabolites, increased oxygen-induced retinopathy and CNV in vivo. Exposure to selected ω-3 LCPUFA metabolites of CYP2C significantly reversed the suppression of both angiogenesis ex vivo and endothelial cell functions in vitro by the CYP2C inhibitor montelukast. CONCLUSIONS: Inhibition of CYP2C activity adds to the protective effects of ω-3 LCPUFA on pathological retinal neovascularization and CNV.