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X. Liang, S. Xie, X. Ding, T. Li, S. Yu, X. Guo, H. Chen, S. Tang, L. Cao, J. Shao; Tetramethylpyrazine(TMPz) Induces Cultured Human Retinal Capillary Endothelial Cell(HRCEC) Apoptosis and Inhibits Retinal Neovascularization in Oxygen-Induced Retinopathy(OIR) Mice. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1743.
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Tetramethylpyrazine (TMPz) had been used for its protective effect in myocardial ischemia/reperfusion injury rats. In this study, we investigated the effect of TMPz in cultured human retinal capillary endothelial cells (HRCEC) and oxygen-induced retinopathy (OIR) mice.
HRCEC were cultured with CoCl2 (hypoxia) and without (normoxia) and treated with 100µg/ml (group1), 200 µg/ml (group 2) of TMPz or no TMPz(control). HRCEC proliferation were tested by methylthiazoletrazolium(MTT) assay, and cell apoptosis were tested by flow cytometry. In an in-vivo study, TMPz were injected intraperitoneally 200mg/Kg once a day from the time when mice were put back to room air(P12) to P16 in OIR mice. At P17, mice were perfused with fluorescein-dextran and retinal neovascularization (NV) areas were measured on retinal flat mount or eye frozen sections stained with griffonia simplicifolia lectin B4 (GSA). Levels of mRNA and protein of VEGF in retina and HRCEC were measured by RT-PCR and ELISA respectively.
There was a 27.5%(P<0.01), 77.3%(P<0.0001) reduction of cell proliferation in group 1,2 of hypoxia HRCEC, and 24.9%(P<0.001), 64.7%(P<0.0001) reduction in group 1,2 of normoxia HRCEC compared to control respectively. Apoptotic rate of HRCEC in group 1,2 increased 3 times(P<0.0001), 9 times(P<0.0001) in hypoxia group and 11 times(P<0.0001),22 times(P<0.0001) in normoxia group compared to control respectively. In our in vivo study, retinal NV areas reduced 44.21%(P<0.0001) on flat mount and 52.38%(P<0.0001) on frozen section compared to control respectively. Levels of mRNA and protein of VEGF decreased both in vitro and in vivo.
TMPz inhibited proliferation of HRCEC under hypoxia and normoxia, and induced apoptosis. It also inhibited retinal neovascularization in OIR mice. The underlying mechanism in vitro and in vivo maybe via down regulation of the expression of VEGF.
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