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F. Valamanesh, A. Torriglia, F. Sennlaub, M. Savoldelli, F. Behar-Cohen; Intravitreal Injection of Triamcinolone Acetonide in the Rat Induces Modifications in the Choriocapillary Vessels. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1227.
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To study the potential influence of triamcinolone acetonide (TA) on choriocapillaries vessels in the rat and its potential toxicity on endothelial cells in culture.
Lewis rats received an intravitreal injection of 4µg of TA (in BSS) and were sacrificed one month thereafter. Both electron microscopy (EM) and vascular casts were performed for vessels analysis. For in vitro experiments, subconfluent endothelial cells were treated with 0.1mg/ml TA with or without prior dissolution in 0.1% ethanol. Control cells were either untreated or exposed to 0.1% ethanol. Cell viability was evaluated at 24 hours using MTT and Lactate dehydrogenase (LDH) assay. Apoptosis was evaluated by TUNEL assay and annexin-binding. Immunohistochemistry was performed with anti-apoptosis inducing factor, cytochrome C, Microtubule-associated protein (MAP)-light chain 3 (MAP-LC3) and LEI/L-Dnase II antibodies. Monodansylcadaverine staining was also performed.
EM analysis showed vacuolization of endothelial cells in the choriocapillaries as well as in RPE cells. Scanning electron microscopy analysis of vascular casts showed no changes in retinal vasculature but reduced diameter in TA injected eyes as well as a significant increase in space between vessels. In vitro, TA induced a significant reduction of cell viability on MTT assay, more intense with the crystalline form than with TA in 0.1% ethanol, but all tested markers of cell death were negative.
TA induces vasoconstriction of choriocapillaries and endothelial cell changes. Leading to a decrease in the endothelial cells this can contribute to the anti angiogenic and / or anti edematous effects of corticosteroids and the molecular mechanisms involved will be further explored.
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