RU2541743C1 - Method for simulating axial myopia - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: axial myopia is simulated experimentally in chinchillas. The simulation is performed by the daily administration of transretinoic acid 0.3-0.6 ml in the concentration of 0.04-0.07 mg per normal saline 1 ml into the internal carotid artery for 6 months. The administration is performed for 6 months.

EFFECT: method enables providing more accurate reproduction of the pathological process, approaching the simulation to the natural clinical course.

2 dwg, 2 tbl, 1 ex

Description

The invention relates to medicine, namely to ophthalmology, and can be used in scientific and clinical practice in the development of conservative and surgical methods for the treatment of myopia.

There is a known method of modeling experimental myopia in which rabbits under the conjunctiva of the eye in the equatorial zone in four segments are injected with a freshly prepared solution of papain in physiological saline at 37 ° C at the rate of 0.005 mg per 1 ml of solution of 0.25 ml in each segment. Clinical, histological and electron microscopic studies have proved the development of myopic disease in an experimental animal (USSR patent No. 1573466, 1990). Macroscopically, on the surface of the sclera in the area of the conjunctival arches, zones of thinning of the sclera were determined in the form of typical myopic staphylomas with choroid visible through the sclera. Clinically on the fundus, the authors noted the development of choroidal dystrophy with pigmentation of the retinal pigment epithelium, progressive chorio-vasculosclerosis and the formation of white dystrophic foci in the equatorial zone. Biomicroscopy revealed the development of dystrophic changes in the iris. The intensification of clinical refraction, an increase in the anteroposterior size of the eye were determined. In the study of hemodynamics revealed a decrease in blood supply to the choroid of the eye. Histological and electron microscopic studies of sclera and choroid revealed a thinning of the fibrous and choroid membranes with significant disturbances in the structure of collagen fibers and fibrils, up to their granular decomposition.

However, the method has several disadvantages: modeling is carried out by administering the drug in four segments, which is traumatic for the eye, the native enzyme preparation papain is rapidly inactivated by the system of body inhibitors, which requires its daily administration, which leads to an increased risk of toxic-allergic reactions.

A known method of modeling experimental myopia is based on an increase in intraocular pressure against a background of a decrease in pressure in the vessels of the eye under the combined effect of a 3.0% sodium chloride solution and 1.0% nicotinic acid solution during the growth period of a rabbit organism (Barkovskaya T.N., 2001) . By the eyes of rabbits of the chinchilla breed, the author reproduced myopia up to 2.0 diopters in this way. The anteroposterior size of the eye increased from 20.5 to 23.9 mm, and morphologically revealed changes in the form of thinning of all layers of the sclera with fragmentation of its fibers and increased accumulation of glycosaminoglycans.

However, this method does not reproduce the natural conditions for the formation of this disease.

The results of experimental studies have shown that various tissues of the eyeball (choroid, retinal pigment epithelium) are able to synthesize retinoic acid and it is involved in the regulation of eyeball growth. The concentration of retinoic acid in the body must be maintained at a strictly defined level. Excess retinoic acids can inhibit the synthesis of scleral proteoglycans. Inhibition of proteoglycan synthesis weakens the sclera and creates a structural basis for the occurrence of myopia.

To date, 6 types of retinoic acid receptors (RAR alpha, RAR beta, RAR gamma, RXR alpha, RXR beta, and RXR gamma) have been found in human scleral fibroblasts. In the absence of an excess of retinoic acids, receptors in fibroblasts are inactive. In excess - the RAR alpha receptor gene is activated, which is considered as a potential gene for the development of myopia.

At the same time, transretinoic acid is a natural endogenous metabolite of vitamin A, belonging to the class of retinoids and normally present in blood plasma at a concentration of 0.5-1.5 ng / ml. Under the action of intracellular isomerases, transretinoic acid is metabolized to 13-cisretinoic acid and oxidized in the liver by P450 cytochrome to 4-hydroxymetabolites.

Given the foregoing, it is obvious that a change in the concentration of retinoic acid in the body can be used to create a model of myopia.

In our opinion, the closest analogue of our proposed method is the use of transretinoic acid to simulate myopia, which is introduced to guinea pigs 3 times in the amount of 25 mg / kg along with 0.4 ml of peanut butter on 7.9 and 11 days from birth ( Sally A. McFadden, Marc HC Howlett, James R. Mertz, Retinoic acid signals the direction of ocular elongation in the guinea pig eye, Vision Research 44 (2004) 643-653).

However, such a brief introduction of transretinoic acid, as well as the use of a metabolite with food, does not allow you to control the level of the metabolite in the blood and, as a result, in the tissues of the eye, increase the accuracy of reproduction of the pathological process and bring the model closer to the course of natural pathology, which is a pathological process stretched over time.

The objective of the invention is to improve the above method of modeling axial myopia.

The problem is solved due to the fact that in the method for simulating axial myopia in laboratory animals, 0.3-0.6 ml of transretinoic acid solution at a concentration of 0.04-0.07 mg transretinoic acid per 1 ml is injected daily into the carotid artery for 6 months daily saline solution.

The method is as follows:

For premedication to an animal, in particular a chinchilla rabbit, a 2% solution of xylosine hydrochloride (rometar) is administered. After 10-15 minutes, zoletil - 50 at a dose of 6.6 mg / kg body weight is injected intravenously into the marginal vein of the ear.

After general anesthesia, a permanent Vasofix Certo 24G catheter is inserted into the internal carotid artery of the experimental animal.

The correct position of the catheter is monitored by conducting a X-ray of the skull in lateral projection after administration of 0.5 ml of Omnipack X-ray contrast material (Amersham Health, Cork, Ireland) at a concentration of 300 mg / ml.

0.3-0.6 ml of transretinoic acid is administered daily through a catheter for 6 months in the form of a solution with a concentration of 0.04-0.07 mg of transretinoic acid per 1 ml of saline.

A solution for daily administration of transretinoic acid is prepared under dim light. The powder is diluted in 100% ethanol, then 0.9% NaCl is added to the resulting solution to a final concentration of 0.04-0.07 mg / ml.

The proposed method was used to model axial myopia on 5 male chinchilla rabbits with an initial body weight of 2.0-2.5 kg. The control group consisted of 5 animals, which after the catheter was inserted into the left internal carotid artery, transretinoic acid was not administered.

Previously, a complete ophthalmological examination of both eyes was performed in experimental animals, including ophthalmoscopy, biomicroscopy (slit lamp SL-30 from Opton, Germany), determination of clinical refraction (Mirae Optics Charops MRK-2000 autorefractometer, Japan), determination of anteroposterior the size of the eye - echobiometry (ophthalmobiometer "Ultrasonic Biometer Model 820"). Ophthalmological control according to the scheme was performed 1 time in 3 months. Evaluation of the results was given according to the results of biomicroscopy, ophthalmoscopy, autorefractometry, ECHO-biometry.

As a result of studies, it was found that in the control eyes of experimental animals, hyperopic refraction persisted throughout the observation period. Its value in the control eyes of animals at the beginning of the experiment was + 4.05 ± 0.17 and after 6 months decreased to + 3.62 ± 0.48 (p <0.05). In experimental eyes, there was an increase in refraction from + 3.92 ± 0.4 to - 0.78 ± 0.2 (p <0.05) (Table 1).

The anteroposterior axis of the eyeball in the experimental eyes of experimental animals increased from 16.00 ± 1.59 to 18.84 ± 1.47 (p <0.05), while the anteroposterior axis of the eyeball of the control eyes of animals did not significantly change (tab. .2).

The method developed by us made it possible to obtain an average refractive effect after 6 months - 0.78 ± 0.2 diopters.

An example of the method

The rabbit was examined by biomicroscopy, ophthalmoscopy, pathology was not found. The animal was under general anesthesia and a Vasofix Certo 24G catheter was inserted into the internal carotid artery (Fig. 1). The correct position of the catheter was monitored by conducting an X-ray of the skull in lateral projection after administration of 0.5 ml of the Omnipack radiopaque substance (Amersham Health, Cork, Ireland) at a concentration of 300 mg / ml (Fig. 2).

Through an established catheter, 0.5 ml of a solution of transretinoic acid at a concentration of 0.06 mg per 1 ml of saline was injected daily for 6 months. Toxic-allergic reactions in the animal were not detected throughout the entire simulation period.

When examining the experimental animal after 6 months, an increase in the anteroposterior size of the eyeball to 18.5 mm and an increase in clinical refraction to -0.5 diopters were observed.

Thus, the results of our experimental studies have shown that a method based on exposure through systemic hemodynamics is most effective in modeling axial myopia. The introduction through a catheter installed in the internal carotid artery of 0.3-0.6 ml of a solution of transretinoic acid at a concentration of 0.04-0.07 mg per 1 ml of saline solution contributes to the emergence of an axial form of myopia with clinical signs characteristic of this process.

The method is simple to implement, does not require expensive equipment and drugs, can be used in scientific and clinical practice in the development of conservative and surgical methods for the treatment of myopia.

Thus, the proposed method for modeling axial myopia in comparison with the prototype allows to increase the accuracy of reproduction of the pathological process, to bring the model closer to the course of natural pathology.

Table 1 Clinical refraction of the eyes of experimental animals before and after administration of trans-retinoic acid Observation Dates Clinical refraction of animal eyes experienced control Exodus + 3.92 ± 0.4 + 3.99 ± 0.32 6 months -0.78 ± 0.2 * + 3.46 ± 0.36 * Note: * p <0.05 compared with refraction before the experiment

table 2 Anteroposterior eye size of experimental and control animals before and after administration of transretinoic acid Observation Dates Anteroposterior eye size experienced control Exodus 16.00 ± 1.59 15.17 ± 1.16 6 months 18.84 ± 1.47 * 15.62 ± 0.98 Note: * p <0.05 compared to the original PZR

Claims (1)

A method for simulating axial myopia, including introducing a rabbit of the chinchilla breed into the internal carotid artery for 6 months daily of 0.3-0.6 ml of a solution of transretinoic acid at a concentration of 0.04-0.07 mg per 1 ml of saline.

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