PHOTOCHEMICALLY-INDUCED LESION OF THE RAT RETINA - A QUANTITATIVE MODEL FOR THE EVALUATION OF ISCHEMIA-INDUCED RETINAL DAMAGE

The effects of ischemia-induced retinal damage were quantitatively eva luated in rats with the aim of obtaining a suitable model to study the pathogenesis of the loss of retinal neurons after ischemic episodes. Anaesthetized rats were injected with 80 mg/kg i.v. of the fluorescein rose bengal dye and one eye was exposed to cold light for different p eriods (from 5 to 30 min). The animals were sacrificed at different ti mes (1 and 4 hr; 2 and 7 days) after the lesion and the photochemicall y-induced damage was evaluated. The damaged retinae appeared thicker, numerous neurons of the inner nuclear layers showed swelling of the pe rinuclear cytoplasm and the retinal vessels were enlarged. The activit y of choline acetyltransferase (ChAT) and glutamic acid decarboxylase (GAD), two marker enzymes of the GABAergic and cholinergic neurons, si gnificantly decreased, indicating a degeneration of GABAergic and chol inergic amacrine cells.