Histological changes of adrenal gland under conditions of immobilization stress on the background of hypothyroidism

Abstract

Summary. The action of the stress factor, regardless of its origin, causes a chain of protective reactions of the body. Adrenal gland is a stress-sensitive organ, the development of adaptation mechanisms under these conditions can be characterized by its morphological state.

The aim of the study – to investigate the features of histological changes in the adrenal glands of rats under the conditions of immobilization stress, which occurred on the background of experimental hypothyroidism.

Materials and Methods. The experiment was conducted on 20 sexually mature white male rats. Hypothyroidism was modeled by daily per os injection using a probe of the pharmacopoeial mercazole thyreostatics at a dose of 25 mg/kg during the 21st day. Immobilization stress was modeled by tying rats in a supine position by 4 limbs without restricting head mobility for 3 hours. The study was conducted 2 hours later (anxiety stage) after the end of the stressor. Histological studies were carried out according to generally accepted methods.

Results. Microscopic examination of the adrenal glands under conditions of immobilization stress revealed signs of destructive changes in the organ. Single blood-filled and dilated vessels were present. Cells with signs of destruction and swelling of the cytoplasm were determined. The presence of endocrinocytes with a small amount of lipid inclusions unevenly distributed in the cytoplasm of cells was characteristic. Microscopic studies of the adrenal glands 2 hours after the action of the stress factor on the background of hypothyroidism showed more significant changes in the structure of the organ. Perivascular edema was present. The connective tissue capsule was thickened. Single cells were necrotically altered and had pyknotic nuclei. Numerous endocrinocytes were poor in lipid inclusions, or completely devoid of them. In the medulla, there were destructively changed chromaffinocytes, with phenomena of edema and vacuolization of the cytoplasm. There were numerous blood vessels with blood-filled, dilated lumens.

Conclusions. Under conditions of stress, destructive changes in the structure of the organ were established, which were characterized by engorgement of blood vessels and swelling of their walls, destruction of endocrinocytes of all zones. Under the conditions of the combined effect of immobilization stress with hypothyroidism, more significant changes in the structure of the organ were observed – reorganization of the vessel walls, thickening of the organ capsule, disorganization of the structural components of the stroma of the organ, and the presence of destructively and necrotically altered endocrinocytes.