Suppression of laser-induced choroidal neovascularization by oral tranilast in the rat.

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Abstract

PURPOSE: To determine whether tranilast administered to pigmented rats inhibits formation of choroidal neovascularization induced by diode-laser photocoagulation. METHODS: Female Brown Norway rats were used. On day 0, choroidal neovascularization was induced by diode-laser photocoagulation, using a setting of 75 microm spot size, 0.1 second's duration, and 100 mW intensity. Tranilast (200 or 600 mg/kg per day) was administered orally twice daily for 14 days. Indomethacin (1 and 5 mg/kg per day) was administered orally once a day for 14 days. Choroidal neovascularization was evaluated on days 7 and 14 by fundus photography and fluorescein angiography. Late-phase fluorescein angiography was scored according to four grades. The animals were killed on day 14, and the lesions were evaluated histologically. RESULTS: In the vehicle-treated group, 34 of 35 burns (97%) showed fluorescein staining and late leakage on day 14. Choroidal neovascularization was identified by light microscopy in all the lesions that showed fluorescein staining and late leakage. The score of fluorescein staining was reduced in rats given 200 mg/kg per day or 600 mg/kg per day (P < 0.01) of tranilast. The thickness of the laser-induced lesions was reduced in a dose-dependent manner by tranilast, a significant difference was observed with 600 mg/kg per day (P < 0.05). Oral indomethacin treatment did not reduce fluorescein staining on day 14. CONCLUSIONS: Tranilast inhibits the development of choroidal neovascularization in this experimental model.