Effects of posterior sub–Tenon’s administration of triamcinolone acetonide on leukocyte–endothelial interactions in the ischemic retina

Abstract

Abstract: : Purpose:Recent studies reported that intraviteal or posterior sub–Tenon’s injection of triamcinolone acetonide (TA) is effective for the treatment of macular edema resulting from retinal microcirculatory disturbances such as diabetic retinopathy and retinal vein occlusion. We studied the effects of periocular administration of TA on leukocyte–endothelial interactions after transient retinal ischemia. Methods: Transient retinal ischemia for 60 minutes was induced in male Long Evans rats by the temporal ligation of the optic nerve. After the induction of ischemia, experimental eyes received posterior sub–Tenon’s injection of TA (2 mg). For controls, the same volume of saline was administered. At 24 hours after reperfusion, we evaluated leukocyte dynamics in the retinal microcirculation using acridine orange digital fluorography. The mRNA expression of P–selectin and intercellular adhesion molecule–1 (ICAM–1) in the retina was semiquantitatively studied with RT–PCR in the TA treated and control rats. Results: The rolling of leukocytes in the retinal veins after ischemia was prominent in the vehicle treated rats (32.5±2.1 cells/min). No leukocyte, however, showed rolling in the TA treated rats. The number of accumulated leukocytes in the retina 24 hours after ischemia was significantly reduced in the TA treated rats (831±99 cells/mm²) as compared with that in the vehicle treated animals (971±81 cells/mm², P<0.05). The TA treatment decreased the mRNA expression of both P–selectin and ICAM–1 in the retina. Conclusions: The present study demonstrated that TA effectively inhibited leukocyte–endothelial interactions in the retina after ischemia. Downregulation of adhesion molecules of retinal vascular endothelium by TA may play a role.

Keywords: ischemia • retina • retinal adhesion