[Effect of a hypoxic-hypercapnic gaseous medium and lowered temperature on the functional state of the rat hypothalamo-hypophyseal-thyroid system].

Radioimmunoassay and morphometry were used to study the time course of the function of the hypothalamus-pituitary-thyroid system in rats cooled under the conditions of the increasing hypoxia-hypercapnia. The changes in the function of this system exposed to combined factors were phasic in nature. The trend of the changes and functional activity of the test system depended, at individual times of cooling, on the pattern of environmental factors and reconstitution of the general body reactivity. It is suggested that the changes in the function of the hypothalamus-hypophysis-thyroid attest to the involvement of this part of the endocrine system in the body response to cooling and are thus one of the essential components in neuroendocrine regulation of the adaptive process responsible for the increased resistance of the animals to the exposure to extremal environmental factors.