Production of platelet-activating factor in photocoagulated retinas

Platelet-activating factor (PAF), an 1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine, plays an important role in tissue inflammation and ischemia. Previous results from our laboratory have shown that PAF is synthesized in the cornea after injury and that PAF antagonists reduced inflammation in an experimental model of anterior uveitis. This study was conducted to determine the effect of photocoagulation on PAF levels in the retina. Dutch belted pigmented rabbits underwent panretinal photocoagulation in the right eye with an argon blue-green laser. The left eye of each animal served as the control. Four hours later, the animals were killed. PAF was isolated from retinal extracts using high-performance liquid chromatography (HPLC) and was quantitated by platelet aggregation activity. In each animal the level of PAF in the photocoagulated retina was one-and-one-half to four times higher than in the control retina. The specific PAF antagonist BN52021 completely inhibited PAF activity in each sample. Due to the proinflammatory properties of PAF, its increase after laser application may be implicated in some of the clinical side effects seen after this therapy.