[Dependence of organism stability on chronic stress from thyroid status]

In experiences on 108 male rats, the effect of acute (immobilization during 3 hrs) and chronic (immobilization for 3 hrs during 5 days) stresses on the organism general stability was studied as evaluated with changes of body weight, adrenal glands, spleen, thymus relative mass, gastric mucosa state, animals physical endurance. Chronic stress evoked more obvious decreasing of spleen and thymus relative mass than the acute one, as well as lesion of gastric mucosa accompanied with decrease of the rat resistance to physical loading. Thyroid function suppression by merkazolil (1.2 mg/100 g body weight during 14 days) promotes further the reduction of the organism stability in acute and, especially, in chronic stress, while physiological doses of thyroid hormones (5.0-8.0 mcg of thyroxin on kg of body weight during 28 days), on the contrary, increased it in both stress conditions. Existence of the organism stability dependence on thyroid status both in acute and chronic stress proves iodothyronine's important role in the organism antistress-system.