Age-related morphofunctional changes of thyroid mast cells under low-intensity laser irradiation (an experimental study)

Abstract

Purpose: to study the dynamics of morphofunctional parameters of thyroid mast cells under low-intensity laser irradiation depending on age. Material and methods. The experiment was conducted on 96 white male laboratory rats of the Wistar breed. Animals were divided into four groups: 1 – control young, 2 – control old, 3 – young, low-intensity laser irradiation, 4 – old, low-intensity laser irradiation. A single laser irradiation session in continuous mode (wavelength – 970 nm, power – 1 W, exposure – 60 s) was made in the projection of thyroid gland. The animals were removed from the experiment 1 hour and 1, 3 and 7 days after exposure to laser light. Thyroid preparations were fixed in the formalin; histological sections were prepared and stained with toluidine blue; the morphometric analysis was performed to determine the number of thyroid mast cells and their varieties depending on the granular saturation level and degranulation degree.Results. The reaction of thyroid mast cells of experimental animals to laser exposure had some specific features: in young animals there was the increase in the number of cells and in their synthetic activity with the increase in granular saturation level and with the decrease in degranulation level which indicates an increased migration of cells into the thyroid gland and a pronounced adaptive reaction of the entire population of mast cells of the body. In old animals, exposure to laser light caused degranulation activity of thyroid mast cells with decrease in the level of granular saturation. No changes in the number of cells indicates that the reaction is limited within the organ contours.Conclusion. The results obtained expand our understanding of specific reactions of mast cells to laser exposure and confirm the need for individual correction of low-level laser therapy depending on age.