Features of local synthesis of neurotrophic factors under the influence of fractal stimulation phototherapy in a model of retinal pigment epithelium atrophy on rabbit

Introduction. It is assumed that in degenerative diseases of the retina, photostimulation with fractal dynamics signals activates neuroplasticity, increasing the effectiveness of visual rehabilitation. Previously, we demonstrated the positive effect of fractal optic stimulation (FS) on the intraocular synthesis of neurotrophins in rabbits without ophthalmopathology and proved the safety of long-term courses of photostimulation for the retina. Purpose of the study: to evaluate changes in the intraocular production of neurotrophic cytokines against the background of the use of low-intensity fractal optical therapy in the model of retinal pigment epithelium (RPE) atrophy in an in vivo experiment. Material and methods. The study material was vitreous body (VH) samples of 38 (76 eyes) Soviet Chinchilla rabbits with a model of RPE atrophy. Depending on the type of exposure used, animals with RPE atrophy were divided into groups: the main group – 18 animals (36 eyes – FS), the control group – 18 animals (36 eyes – exposure to light from an incandescent lamp). The comparison group consisted of 2 rabbits (4 eyes) with RPE atrophy without exposure. Photostimulation sessions were carried out daily. The duration of each FS session was 20 minutes. The duration of FS courses ranged from 7 to 90 days. The concentrations of BDNF, CNTF, IL-6, NGF, and PEDF were determined in the CT samples using enzyme immunoassay. The results were recorded using a Cytation 5 multifunctional photometer. Results. PEDF, BDNF, and NGF were detected in 100% of the CT test samples from the main and control groups of animals. IL-6 was detected only in 1 case, and CNTF was not detected in the samples. For the first time, the dynamics of intraocular production of neurotrophic factors was determined under the influence of fractal photostimulation on a model of RPE atrophy. Under the influence of FS, the level of BDNF production statistically significantly increased in the eyes of animals with RPE atrophy and indicated the initiation of reparative mechanisms in the retina in response to RPE damage. With an increase in the duration of the course of light stimulation in the main and control groups, a gradual weakening of the intraocular BDNF synthesis was noted, more rapid in the control group. Of particular interest were the changes in intraocular PEDF production under the influence of FS courses of different durations: individual analysis demonstrated an increase in intraocular cytokine production in 16.7% of eyes after a 1-week course of therapy with a maximum level of 58.7 pg/ml, an increase in the number of therapy sessions led to a significant decrease in its concentration in the CT in 80% of cases. Conclusion. The results of the study allow us to conclude that FS affects the production of neurotrophic factors in RPE atrophy in the experiment: the most noticeable effects were found in relation to PEDF and BDNF. Individual analysis of changes in local PEDF synthesis indicates the advisability of prescribing a 1-week FS course lasting 1 week in the treatment of macular pathology associated with impaired RPE function, photoreceptors (for example, in AMD). The data obtained seem important for the development of the FS method and its translation into the clinic for visual rehabilitation of patients with neurodegenerative diseases of the retina.