Retinoprotective effects of Retinalamin studied in an experimental model of photochemical damage to rabbit retinas

Abstract

The study was conducted on 36 rabbits (72 eyes) randomized into 4 equal groups: two experimental groups received parabulbar injections of Retinalamin («Geropharm», Russia) in each eye in dosages of 0.25 mg/kg in a course of 10 days starting from day 1 and day 10 of the experiment, respectively, and two control groups that received injections of normal solution with the same regimen. To simulate photochemical damage to the retina, exposure to light with a wavelength of 405 nm, a power density of 5 mW/cm2 and daily exposure time of 4 h was performed for 20 days. Multifocal and flicker 30 Hz electroretinogram (mfERG and fERG) were recorded, and histological studies of retina samples with quantitative assessment of retinal cells apoptosis by the TUNEL method were conducted before, as well as 10, 20 and 30 days after the start of light exposure. Ophthalmoscopic signs of light-induced retinal degeneration were revealed 6-10 days after start of exposure in all groups. When registering mfERG and fERG in all groups, there was a significant decrease in the amplitude of N1 and P1 peaks, retinal density of the bioelectric response of the P1 component, as well as the amplitude of fERG on days 10 and 20 after the beginning of light exposure (p<0.001 in comparison with the background values), and a slight increase in the indicators on day 30. Histological examination revealed a significant decrease in the number of cells in the outer nuclear layer and an increase in the proportion of apoptotic cells in the outer and inner nuclear layers on days 10 and 20 of the experiment, with a decrease on day 30 (after cessation of light exposure). Comparison of the groups receiving Retinalamin injections from days 1 or 10 of light exposure between themselves and the control groups revealed no significant differences in any of the studied parameters (p>0.05). No significant functional and morphological evidence of neuroprotective effects of Retinalamin were found in the model of photochemical damage to rabbit retinas.