INVESTIGATION OF AMINO ACIDS’ LEVELS IN THE VITREOUS BODY OF EXPERIMENTAL ANIMALS IN REGMATOGENIC RETINAL DETACHMENT

The article presents the results of studying the levels of amino acids in the vitreous body of rats with rhegmatogenous retinal detachment at different stages of modeling the pathology (on the 3 rd , 5 th and 7 th day). In animals with modeling RRD, was observed a significant increase in the level of alanine, aspartate, glycine, glutamic acid compared with rats of conditionally intact group; maximum changes in indicators were observed on the 7th day of the study. The obtained data are explained by significant neurochemical changes of the glutamatergic system of the neural retina, which cause excitotoxicity (as a result of massive release of neuronal glutamate) and structural changes. In the study of the level of valine, histidine, tyrosine, phenylalanine and methionine, it was found that these amino acids are not involved in the pathogenesis of RRD, so their level does not change. The obtained experimental data deepen the existing pathophysiological data on the pathogenetic links of rhegmatogenous retinal detachment in the early stages of its progression, which is important for practical ophthalmology to develop effective pharmacotherapy of this disease.

It is known that as a result of RRD there are significant neurochemical changes that develop from several days to several weeks. The study of the distribution of amino acidsneurotransmitters: glutamate, glycine, metabolic amino acids aspartate and glutamine in experimental retinal detachment showed that in this case there are changes in the glutamatergic system of the neural retina, causing massive release of methane changes [6,7,10].
According to the literature data were confirmed experimentally in a clinical study studying the aminoacid profile of the vitreous and vitreal content in patients with RRD with different clinical characteristics [4].
A more in-depth study of amino acid levels in VB rats in experimental modeling of RRD can supplement existing data on the pathogenesis of this disease and contribute to the correct choice of appropriate pathogenetic therapy.
The aim of the study was to establish the changes in amino acid levels in the VB rats under the conditions of experimental RRD.

Materials and methods. Experimental studies were performed on 36 brown
Norwegian male rats, which were divided into 2 groups (18 animals in each group): 1 groupconditionally intact control (without retinal detachment)animals that were underwent paracentesis of the anterior chamber with removal of its moisture and retinal puncture without the introduction of any substance under the retina; 2 grouprats, which reproduced RRD by the method [12] (control pathology) based on the study of apoptosis induction by apoptosis-417 inducing factor. After puncture of the anterior chamber through the corneal limb for reducing intraocular pressure, approximately half of the superonasal-lower temporal neurosensory retina was separated by subretinal injection of 1 % sodium hyaluronate into the subretinal space.
The study of the amino acid composition of VB changes in rats with simulated RRD was performed on the 3rd, 5th and 7th day of the experiment, which allows a more thorough study of pathogenetic changes in the studied pathology. For this aim, the animals were removed from the experiment sequentially -6 animals in each of these terms, both from the group of control pathology and from the group of conditionally intact control.
To achieve the aim of our work, we analyzed the level of the following amino acids: alanine, arginine, aspartate, valine, histidine, glutamic acid, glycine, phenylalanine, tyrosine and methionine. The amino acid profile was studied in the vitreous body of the eye. The Statistical processing of the obtained results was performed using the program "Statistica 8.0". The probability of differences between the indicators of the control and experimental groups was determined by Student's test [3].
Results and discussion. The study of amino acid levels in the VB of rats was carried out in the dynamics: on the 3rd, 5th and 7th day of experimental modeling.
The level of alanine on the 3rd day of the study increased in 1.5 times (p<0.05), on the 5th dayin 1.4 times (p<0.05); the level of aspartate on the 3rd day of the study increased in 9.0 times (p<0.05), on the 5th dayin 10.7 times (p<0.05); the level of glycine on the 3rd day increased in 2.1 times (p<0.05), on the 5th dayin 2.2 times (p<0.05); the level of glutamic acid on the 3rd day increased in 7.0 times (p<0.05), on the 5th dayin 8.0 times (p<0.05) compared with similar indicators of conditionally intact rats. In the study of arginine levels, no significant differences were found (Table 2). Table 2 The levels of alanine, arginine, aspartate, glycine and glutamic acid in vitreous body of rats 1. * -p<0,05 compared with the intact group of animals.
2. nthe number of animals in each group (n=6).
In animals that simulated RRD on the 7th day of the study showed a significant increase in certain amino acids: the level of alanine increased in 1.4 times, aspartatein 11.5 times (p<0.05), glycinein 2.3 times (p<0.05), glutamic acidin 7.9 times (p<0.05) compared with rats of conditionally intact group. Levels of other amino acids increased insignificantly (Fig. 2).
The obtained data are explained by the fact that as a result of retinal detachment there are significant neurochemical changes: increased levels of glutamate, glycine, alanine, aspartate due to changes in the glutamatergic system of the retina, which causes massive release of neuronal glutamate and causes concomitant changes in its metabolism. In turn, the release of neuronal glutamate causes excitotoxicity and initiates structural changes [6].
Accumulation of glutamate leads to excitotoxic effects by increasing the stimulation of its receptor, increasing the level of intracellular calcium and initiating a cascade of changes that will eventually lead to apoptosis or necrosis [7].
Accumulation of glutamate and aspartate in the VB of RVS rats may be the result of their release from dead retinal ganglion cells, leading to further neuronal damage. Increased excitotoxicity of glutamate and aspartate in VB is associated with ischemic processes in the optic nerve [10]. Elevated glycine levels may be due to retinal ischemia caused by RRD in rats [11]. Our results in modeling RRD in rats correlate with data obtained by other researchers [6,7,10,11].
Thus, we can assume that the duration of experimental reproduction of RRD has a direct impact on amino acid levelsprolonged exposure to elevated levels of glutamate, alanine and glycine leads to more significant retinal damage and irreversible changes in it with necrosis [11,13,14].
The obtained data provide an opportunity to deepen the existing knowledge about the pathogenesis of RRD in order to develop and implement more effective pharmacocorrection of this disease.