STATE OF THE PROTEINASE/INHIBITOR SYSTEM IN RATS IN THE DYNAMICS OF IMMOBILIZATIONAL STRESS ON THE BACKGROUND OF HYPOTHYROIDISM

Abstract

Introduction. In the pathogenesis of many pathological conditions, the violation of the proteinase-inhibitor system is important. In the absence of proper control of proteolysis, a number of pathological conditions, accompanied by the appearance of destructive, inflammatory and immune responses, develops. A number of researchers have established the protective effect of iodine-containing thyroid hormones in stress, realized as a result of their interaction with the cell genome, which leads to stimulation of local stress-limiting systems.

The aim of the study – to establish the peculiarities of the functioning of the proteinase system/proteinase inhibitors under conditions of immobilization stress against the background of reduction of the level of iodine-containing hormones of the thyroid gland.

Research Methods. Hypothyroidism was modeled daily by the introduction of per os tireostatics of Mercazolil (Zdorovia, Ukraine) at a dose of 25 mg/kg during the 21^st day. Acute immobilization was modeled by binding the experimental rats to the back on the 4 limbs without limiting the mobility of the head for a duration of 3 hours. Spectrophotometric and immuno-enzymatic methods were used to study the concentration of iodine-containing hormones of the thyroid gland, the activity of the proteinase system and the content of proteolytic inhibitors.

Results and Discussion. The effect of immobilization stress in rats with pre-modeled hypothyroidism on the parameters of the proteinase-inhibitory system of blood has been investigated. At the stage of the anxiety of the development of the stress reaction in euthyroid animals, an increase in the proteolytic activity of the blood was observed against the background of an increase in the content of α1-inhibitor proteases and α2-macroglobulin, indicating an increase in antiprotoitic potential to inhibit the development of degradation. At the stage of resistance there is a stabilization of proteolytic activity of the blood. However, with prolonged stress (depletion stage), the proteolytic activity of blood again significantly increases with the decrease in the activity of protease inhibitors, indicating the depletion of protective inhibitory reserve.In animals with hypothyroidism, at all stages of the development of a stress reaction, there is a significant increase in proteolytic activity of the blood, and the rates of protease inhibitors are significantly reduced. This leads to a sharp increase in the index of proteolysis, which occurs against the background of increased permeability of lysosomal membranes.

Conclusion. Against the background of hypothyroidism, more intense than euthyroid animals, an increase in the proteolytic activity of blood against the backdrop of inhibition of antiprotozoal activity and an increase in the permeability of lysosomal membranes is observed.