Abstract
Abstract: :
Purpose:St John’s wort (SJW) is a medicinal herb used in the treatment of depression. Hypericin is a constituent of SJW and Protein Kinase C inhibitor. We studied the anti-neovascular effects of Hypericin on ischemic retinopathy and laser-induced choroidal neovascularization in mice. Methods:1. Hypoxic retinopathy model: Seven-day-old (P7) C57BL mice were exposed to 75% oxygen for 5 days, moved to a normal environment and given an intravitreal injection of vehicle (20%DMSO) or Hypericin (10µg per eye). At P17 mice were sacrificed, one eye was frozen and the other enucleated after perfusion with fluorescein-labeled dextran through the left ventricle. Frozen eyes were sectioned, histochemically stained with endothelial cell-specific biotinylated griffonia simplicifolia isolectin B4, and examined by light microscopy. Image-Pro Plus Software was used to identify stained cells on the surface of the retina and their area was measured. The retinae of fluorescein-labeled dextran perfused eyes were dissected, mounted, and examined by fluorescence microscopy. The same software was used to evaluate the non-perfused area (NPA). 2. Laser-induced choroidal neovascularization (CNV): Six-week-old male C57BL mice were anesthetized and pupils were dilated. Eyes were exposed to Krypton laser to rupture Bruch’s membrane, and CNV was induced. Immediately thereafter, eyes were given an intravitreal injection of vehicle (20%DMSO) or Hypericin (10µg per eye). After 14 days, the mice were perfused with fluorescein-labeled dextran through the left ventricle and eyes were removed. The choroid was dissected, mounted, and examined by fluorescence microscopy. Each laser lesion was photographed and scanned. Image-Pro Plus Software was used to measure the area of CNV. An average of 3 to 4 CNV in each eye was used as a single experimental value. Results: Hypericin inhibited retinal neovascularization in mice with ischemic retinopathy (p=0.0125) but had no effect on neovascularization in the mice with laser-induced CNV. Conclusions:Hypericin inhibited retinal neovascularization in mice with ischemic retinopathy, showing that it may be a good candidate for prevention of retinal neovascularization in diabetic retinopathy or premature retinopathy.
Keywords: retinal neovascularization • drug toxicity/drug effects • choroid: neovascularization