CHANGES IN ACTIVITY OF INDUCIBLE NITRIC OXIDE SYNTHASE IN EXPERIMENTAL DIABETIC RETINOPATHY AND METHODS FOR ITS CORRECTION

Diabetic retinopathy according to the World Health Organization reports is known as the main cause of decreased vision and blindness in diabetes. The purpose of the study is to analysis of changes in the activity of inducible nitric oxide synthase in experimental diabetic retinopathy and in various methods of its correction. Materials and methods. The research was carried out on white Wistar rats weighting 180-220 g. The animals were divided into 7 groups: 1st group included 60 intact animals; 2nd group involved 60 animals with modelled diabetic retinopathy (DR) without further correction; 3rd group included 60 animals with modelled DR and subsequent hyperglycemia correction; 4th group included 60 animals with modelled DR, which received subsequent hyperglycemia correction with aflibercept and L-arginine solution administration; 5th group consisted of 60 animals with modelled DR and subsequent hyperglycemia correction by aflibercept and bromfenac administration; 6th group was formed by 60 animals with modelled DR and subsequent hyperglycemia correction by aflibercept, L-carnitine and bromfenac administration; and the 7th group included 60 animals with modelled DR and subsequent hyperglycemia correction by aflibercept, L-arginine solution and citicoline. Results and conclusion. The results obtained demonstrate an increase in the activity of inducible nitric oxide synthase, starting from the 30th day of the experiment and with subsequent progression to the 60 and 108 days of experimental diabetic retinopathy that points out the deterioration of the physiological pathway of nitric oxide synthesis. Correction with hypoglycemic agents in group 3 had a positive effect, but was not able to reduce the activity of inducible nitric oxide synthase, which increased in the 2nd and 3rd stages, thus, there was a need for additional agents. The use of aflibercept and nitric oxide donor in group 4 to correct the progression of diabetic retinopathy significantly reduced the activity of inducible nitric oxide synthase (most effectively on the one hundred and eighty days of the experiment), but did not reach the control values. It has been proved that the correction applied in groups 5 and 6 significantly reduced the activity of inducible nitric oxide synthase but did not reach the control values. Moreover, the marker activity in the group 5 grew up on the 108 day. The study has shown the most effective correction includes a combination of metformin, aflibercept, L-arginine and citicoline given to the rats of group 7, as evidenced by the normalization of malonic dialdehyde levels on the 60 day of the experiment; on the 108 days of experiment there has been a decrease in marker content to control values.