Prostaglandin E₂ changes in the retina and optic nerve of an eye with injured optic nerve

Changes in arachidonic acid metabolism were studied in the optic nerve, the chorioretina, and in the vitreous following crush injury to the optic nerve of rats. Crush injury led to: 1. (i) a 3.9-fold increase in optic nerve prostaglandin type E₂ in vitro production which peaked on day 5 and was followed by a gradual decline, but was still significantly higher than baseline levels by day 12; 2. (ii) a two-fold increase in the chorioretina prostaglandin type E₂ in vitro production which peaked on day 1, and resumed baseline levels by day 3; 3. (iii) a 3.5-fold increase in vitreous prostaglandin type E₂ levels on day 1 which remained at 1.5-2 times higher than baseline levels for the rest of the study period (12 days). The findings indicate that the pattern of changes in prostaglandin type E₂ production by the optic nerve (consisting mostly of white matter) is different from that described for injured brain tissues. The prolonged accumulation of vitreal prostaglandin type E₂ in eyes with damaged optic nerve may lead to undesirable effects on the retina beyond those directly manifested in the retina by altered axonal flow in the injured optic nerve.