EFFECTS OF NICERGOLINE ON RABBIT ELECTRORETINOGRAM DURING RECOVERY AFTER ISCHEMIA IN LIGHT AND DARK

Nicergoline is an ergot alkaloid derivative acting as a neuroprotectiv e agent. In the present investigation, b-wave time-course recovery pro files under both light-and dark-adapted conditions, were studied in or der to evaluate the possible effectiveness of nicergoline in the prote ction of the rabbit retina. Retinal ischaemia was induced by bilateral occlusion of common carotid artery in male rabbit of the Dutch strain . Groups of animals were subjected to 15-, 30- and 60-min periods of i schaemia under pentobarbital anaesthesia. Electroretinogram recordings were simultaneously obtained from both eyes, using, as the stimulus, the brightest flash from a stimulator positioned 15 cm in front of eac h eye. The treatment with nicergoline, administered immediately before the carotid occlusion, induced a significant protection only when the ischaemia seemed to cause retinal damage that the reperfusion alone w as not able to recover completely. Nicergoline did not modify the reco very rate after 15-min or 30-min light-adapted and 15-min dark-adapted ischaemia; in these conditions the controls showed a full recovery. A fter 30-min dark-adapted ischaemia, the maximum recovery of the contro ls was 82%, and nicergoline significantly improved b-wave amplitude at all time points of reperfusion up to the complete recovery. Rabbit re tina was irreversibly damaged by a 60-min ischaemia. In these conditio ns nicergoline significantly increased the percentage of b-wave recove ry both in light-and dark-adapted ERG. Nicergoline, probably on the ba sis of its metabolic actions, seems to be effective in severe conditio ns of hypoxia and is more potent in dark than in light-adapted conditi ons. Its effectiveness in these experimental conditions could be justi fied by the different oxygen consumption of the photoreceptors in ligh t and dark and the different sensitivity of cones and rods to the isch aemia. (C) 1997 The Italian Pharmacological Society.