[The effect of one-time external gamma irradiation at different stages of ontogeny on the thyroid status of rats]. / Vliianie odnokratnogo vneshnego gamma-oblucheniia na raznykh étapakh ontogeneza na tireoidnyi status krys.

A single external gamma-irradiation (1 Gy) of rats on day 35 of their life causes stable structural and functional disturbances in the thyroid gland leading to the development of hypothyrosis at the remote times following irradiation which is demonstrated by the decrease in the concentration of thyroxine in the blood, increase in the thyrotropic function of the hypophysis and inhibition of the activity of tyrosine-dependent enzyme, alpha-glycerophosphate dehydrogenase, in the liver. Disturbances induced by such exposure in the thyroid gland of adult rats are insignificant and compensatory in time.

[Role of the liver in optimization of the thyroid status of rats in hypothyrosis caused by irradiation]. / Uchastie pecheni v optimizatsii tireodnogo statusa u krys pri gipotireoze, vyzvannom oblucheniem.

Experiments were made on 100 random bred rats of various age groups, controls and animals exposed to single external gamma-radiation at a dose of 1 Gy on the 35th day of life. Thyroxine and triiodothyronine concentrations were investigated in peripheral blood and separately in arterial blood, in thyroid, portal and hepatic venous blood. The activity of T4 conversion into T3 by 5'-deiodinating enzymes of the liver microsomal fractions and the activity of the liver mitochondrial enzymes--cytochrome of C-oxidase and alpha-glycerophosphate dehydrogenase were also investigated. A decrease in thyroid excretion of T4 and T3 and T4 blood concentration was noted in rats exposed to irradiation. 5'-thyroxine deiodinating activity of the microsomal enzymes was elevated in the liver of such rats; a T3 ratio in the blood outflowing from the liver was on the increase. A conclusion has been made that 5'-deiodination in the liver of rats with postradiation hypothyrosis is effected as a result of increased production of the most active hormone T3 from less active T4.

[Response of the developing thyroid gland of rats to a single gamma-irradiation in the period of intrauterine development]. / Issledovanie reaktsii razvivaiushcheisia shchitovidnoi zhelezy krys na odnokratnoe vneshnee gamma-obluchenie v period vnutriutrobnogo razvitiia.

A single external exposure of pregnant rats to 2 Gy gamma-radiation caused changes in the functional status of the thyroid gland in offsprings at varying times of the postnatal development. The disturbance of the thyroid hormones balance in the blood, destruction of the thyroid gland combined with high functional tension of secretory elements, and activation of the thyrotropic function of hypophysis were revealed at remote times after irradiation.