Angiogenic properties of catecholamines from the viewpoint of the pathogenesis of retinopathy of prematurity

Purpose : to assess the level of catecholamines norepinephrine and dopamine in rat retina with experimental retinopathy of prematurity (EROP) at a time corresponding to the peak of neovascularization. Material and methods . The study was performed on 41 infant Wistar rats (82 eyes). The rats were divided into 2 groups: the experimental group (with EROP, n = 21) and the control group (n = 20). In order to reproduce the EROP, the newborn rats were placed for 14 days in the incubator together with their mother. Every 12 hours, the oxygen concentration in the incubator ranged from 60 to 15 %. The control group consisted of pups who were held in conditions with a normal oxygen content (21 %) from the moment of birth. The pups were withdrawn from the experiment on the 10th, 14th, 23rd and 28th day, whereupon they were subjected to binocular enucleation followed by histological examination, in addition, the content of noradrenaline and one of the metabolites of dopamine (L-DOPA) was determined in retinal samples of the eyeballs obtained on the 23rd day by highly effective liquid chromatography technique with electrochemical detection. Results . Histological examination showed that in our EROP model the neovascularization peak occurs on the 23rd day of the experiment. At this time rat pups with EROP showed a significantly lower retinal L-DOPA level as compared to the control values (13.99 ng/g and 30.5 ng/g, respectively), and the norepinephrine level significantly exceeded such values (63.7 ng/g and 7.69 ng/g, respectively). Conclusion . A relative deficiency of dopamine and a relative excess of norepinephrine of the rat pups with EROP is noted at the time of the highest vascular activity of the retina. The obtained data confirm anti-angiogenic properties of dopamine and pro-angiogenic properties of noradrenaline in the second phase of EROP development.