Apoptosis and electroretinogram after intravitreal injection of methotrexate in an experimental rabbit model

The aim of this study was to explore the changes in electroretinogram of rabbit retina and apoptosis in methotrexate-induced toxicity. Rabbits were divided into 5 groups. Group I served as control in which saline solutions was injected intravitreally. Methotrexate (800 μg, 1.76 μmol) was injected into the vitreous of both eyes of rabbits groups II, III, IV and V by an insulin injector with a 26 gauge needle under general anesthesia. Retinal function was assessed by electroretinogram (ERG) after 2, 4, 10 days and one month then animals were decapitated. The eyes were enucleated and processed for DNA fragmentation studies by gel electrophoresis to retinae and measurement of caspase-3 activities. The results indicated a significant reduction (p ˂ 0.05) in a- and b-wave, a time-dependent appearance of the typical ladder pattern of internucleosomal fragmentation, a characteristic of apoptosis and increase of relative caspase-3 activity after methotrexate intravitreal injection. Methotrexate lead to apoptosis, increase of caspase-3 and affect retinal function.