ANALYSIS OF HEARING DISORDERS IN RATS WITH AUTOIMMUNE THYROID ACCORDING ABR AND LIGHT MICROSCOPY

Abstract

The aim of the study was to determine the functional and morphological status hearing in rats by recording BAEP and electron microscopy at modeling in them the autoimmune destruction of the thyroid gland.Materials and methods. AIT modeled on the scheme proposed by a group of Chinese scientists - Teng X, Shan Z, Teng W, Fan C, Wang H, Guo R. 2007. Modeling of AIT were carried out on male albino rats [6,7]. The rats were divided into two groups, the first - control, consisted of 10 animals and the second - the main, consisted of 15 rats that had caused AIT experimentally. As confirmation of the development of antibodies in experimental rats surveyed the level of antibodies to thyroglobulin (TgAb) in the blood serum. To determine the functional characteristics of hearing loss in rats was employed registering brainstem auditory evoked potentials (BAEP). Indicators BAEP evaluated 3 times, before the experiment began, on day 57 and 113 from the experiment beginning. When registering BAEP in both groups took into account the presence and amplitude of peaks I, III and V, as well duration of intervals I-III, III-V, I-V. Animals were removed from the experiment by decapitation in a state of ether anesthesia. Conducted taking thyroid tissue to confirm the morphological and the organ of the inner ear structures to identify organic changes. We used the methods of variation statistics. To determine the difference between comparative values, we calculated the Student's coefficient. In addition, was performed correlation analysis on the program QuattroPro 4.0.Results and discussion. Performance levels of TgAb in the control group of rats with experimentally induced antibodies at 112 days of the experiment, expressed in units of density were: the main group - 0.69 ± 0.24; control group - 0.46 ± 0.05 (p <0.01).Indicators wave peaks I, III and V before the experiment group of rats with modeled AT did not differ from the same rats the control group.When we re-registering BAEP 57 days after AIT simulation in rats of the main group, compared with 40.0% in the main marked increase in the amplitude of the peaks I, III, V, and longer intervals I-III, III-V. When registering via BAEP 113 days after AIT simulation in rats of the second group compared with 73.3% in the first marked increase in the amplitude of the peaks I, III, V, and longer intervals I-III, II and V, I-V.On day 57 of the experiment revealed a statistically significant difference in terms of the peak of the first wave of ABR. In the control group of rats, the speed indicator of the emergence of the first wave was 1,51 ± 0,02 msek., And the first wave peak ABR rats of the main group arose after an average of 2,87 ± 0,04 msek.In our opinion this is evidence of the primary lesion is peripheral auditory analyzer.On 113 pilot day was a statistically significant difference between the performance duration intervals I-III (the main group - 2,50 ± 0,07ms; control group - 1,83 ± 0,03ms) and I-V (basic group -4.40 ± 0 , 09ms, the control group - 3,35 ± 0,02ms).On histological specimens obtained thyroid of rats with simulated AIT determined by lymphocytic infiltration, which is accompanied by an increase, and the destruction of follicular cells microscopically clearly distinguishes it from intact rat thyroid medication.Histological examination of the following changes structures of the inner ear of rats of the main group were identified: swelling of cores outer hair cells (OHC), moderate changes in the core circuit portions pyknosis cores, gluing the hair in a single conglomerate OHC.Conclusion. Analyzing the studies, we can conclude that the increase in the duration of occurrence of the peak of wave I and prolongation intervals I-III, IV, and structural changes in the OHC in rats of the main group indicate functionally negative and organic-destructive impact of AIT on the inner ear structure in rats.