Ultrastructural Characteristics of the Mucociliary Barrier in Experimental Hyperglycemia

The article deals with the study of ultrastructural characteristicss of the epithelial layer of the bronchial tree in hyperglycemia in the model of experimental diabetes. Materials and methods. The study was performed on 47 STZ-induced diabetic white rats (male) Wistar line and 43 control rats. Ultramicroscopic features of the components of the mucociliary barrier were studied in identical tissue parts of the respiratory system. The model of the STZ was reproduced by single intraperitoneal administration of streptosotocin (SIGMA, USA) in 0.1 M citrate buffer pH 4.5, in Wistar rats at a dose of 60 mg/kg. The administration of streptozotocin was carried out after a previous 24-hour deprivation of food with preserved access to water. Determination of blood glucose concentration from the caudal vein was carried out by glucose oxidase method. For further studies only laboratory animals with elevated glucose levels (>11 mmol/l) were used. The life of laboratory animals was 18 weeks (after the registration of hyperglycemia). Results and discussion. The investigation revealed the desquamation of the bronchial epithelium with the development of progressive atrophy and transformation of the stroma of the mucociliary barrier in experimental hyperglycemia. We found a change the cellular form in the bronchial epitheliocytes, in the basal cells − electron density of the cytoplasm, in ciliated epithelial cells − disturbance of the regular location of cilia. Moreover, there was some damage to the ciliary apparatus, in the goblet cells – increased osmiophilia of the cytoplasmic matrix and secretory granules in the group of diabetic rats. We also revealed the diameter increase and density decrease of the cilia location of the ciliated epithelium in the group of rats with experimental diabetes. These changes in the group of diabetic rats were accompanied by pronounced dystrophy and degeneration of the multiple ciliated epithelium, which for a long time was replaced by one- or two-row atrophy, or was prone to squamous cell metaplasia. As a result of the conducted stereometric study, it was found out that in the group of rats with STZ, the diameter of the cilia of the ciliated epithelium was 1,1±0,04 μm, which was 1.6 times greater in comparison with similar changes recorded in the control group, where the result is equal to 0,7±0,03 μm. In the course of the study, the density of the cilia was located on the mucosa of the lower airways. In the STZ-group, this indicator was 4,05±0,3 μm2, which was 1,9 times less, when compared with the values in the control group – 7,8±0,4 μm2. Conclusions. Thus, in diabetic rats ultrastructural changes indicate bronchial epithelium changes in the normal phenotype of bronchial epithelium with a disturbance of the regenerative and metabolic processes, manifested in the airways impairment of barrier functions.