THE EFFECTS OF NALOXONE ON RETINAL ISCHEMIA IN RATS

The efficacy of naloxone (NL), a broad spectrum opioid antagonist, on retinal ischemia, was evaluated in a rat model of retinal ischemia wit h histopathologic and morphometric criteria. Two intraperitoneal injec tions of naloxone 3 mg/kg given immediately and 6 hr after reperfusion showed beneficial effects to the retina as evaluated at 2, 7, and 14 days after reperfusion. Morphologically, the naloxone-treated group sh owed better-preserved ganglion cells, nerve fiber layer, and inner nuc lear layer. Morphometrically, in the treated groups, inner retinal thi ckness at all three time points and ganglion cell counts at 7 days sho wed higher values than vehicle controls. This beneficial effect of nal oxone was dose-dependent with a minimal effective total dose of 6 mg/k g. A possible role of opiate receptors in retinal ischemia is suggeste d.