Résumé
The purpose of this study was to investigate the mechanism of the neuroprotective activity of trimetazidine in animal retina stressed by ischemia or kainate. Flash electroretinograms were recorded in guinea
pigs after ischemia, induced by an acute increase in the intraocular pressure (IOP), or after an intravitreal injection of kainate. Treatment with trimetazidine per os afforded a significant protection
of the electroretinogram against the ischemic as well as the excitotoxic insult as an antioxidant (dimethylthiourea) and a nitric oxide synthase inhibitor (nitroarginine) did. The effect of the drug on
the extracellular accumulation of glutamate induced by chemical ischemia was studied by incubating rat retina in vitro. Trimetazidine was able to inhibit the extracellular glutamate accumulation,
which represents the first step of the excitotoxic phenomenon. Then the compound activity on the glial uptake of glutamate was studied in a rat Müller cell line (rMC-1) in culture. Chemical ischemia
inhibited the active 3H-glutamate transport, an effect that was reversed by trimetazidine, at micromolar concentrations. These results demonstrate that trimetazidine which is recognized as an efficient
drug against ischemic injuries, is also capable of protecting the retina against excitotoxicity by reducing ischemia-induced accumulation of glutamate due in particular to glial transporter inhibition.