Morphological differences of the thyroi d gland in spontaneously hypertensi ve rats after exposure to dosed normobaric hypoxia in the different seasons of the year

Abstract

Purpose — to investigate the effect of dosed normobaric hypoxia (DNH) of sanogenic level in spring and autumn periods of the year on the morphometric parameters of the thyroid gland (TG) functional state of the spontaneously hypertensive young rats (SHR line). Methods. The study was conducted on 48 young male rats of SHR line in spring and autumn seasons. Experimental rats were daily received DNH intermittently: 15 minutes deoxygenation / 15 minutes reoxygenation during 2 hours. Duration of experiment was 28 days. Histological preparations from thyroid tissue were prepared according to standard methods. Gland morphometry was performed on digital images using a computer
program «Image J». Results. The obtained data suggest that the 28-day DNH exposure in different seasons has divergent effects on the morphological and functional state of the thyroid gland. Thus, hypoxic mixture of the gland reduces the size of follicles, their inner diameter, index of colloid accumulation, width of interfollicular connective tissue interlayers. After DNH effect, in autumn the growth of thyroid follicular areas, their inner diameter, colloid area, reduced follicular-colloidal index were observed. Conclusions. The dosed normobaric hypoxia in the spring increases the signs of the thyroid gland synthetic activity, while in the autumn (for the majority of the morphometric parameters) — reduces its functional state.