The effect of dried thyroid gland pretreatment upon survival, formation of endogenous spleen colonies and differentiation of haemopoietic cell populations in x-irradiated mice.
Experiments on non-inbred H-strain male mice confirmed that their radioresistance could be increased by a stimulatory action of the thyroid hormones applied for three weeks preceding the radiation exposure. It was found that the 30-day survival after 750R rose between the 1st and the 5th day after the end of the pretreatment. The highest degree of radioresistance was observed, when the radiation exposure fell into the phase of gradual receding of increased metabolic rate. The relevant experimental groups showed a higher frequency of endogenous spleen colonies and an increased granulocytic differentiation of haemopoietic stem cells. Higher colony-forming activity was also found in animals irradiated immediately after the termination of pretreatment with thyroid, but without an increase in survival. The lack of radioprotective effect under those circumstances could be explained by the persisting hypermetabolic effect of the thyroid, and by the fact that an increased proportion of haemopoietic stem cells underwent differentiation into the erythroid line.
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D006412:Hematopoietic Stem Cells / Q000187:drug effects*; D006413:Hematopoietic System / Q000528:radiation effects; D008297:Male; D051379:Mice; D011833:Radiation Injuries, Experimental / Q000517:prevention & control; D013154:Spleen / Q000187:drug effects* / Q000528:radiation effects; D013962:Thyroid (USP) / Q000494:pharmacology*; D013963:Thyroid Hormones / Q000494:pharmacology*; D013997:Time Factors; D014965:X-Rays
D013962:Thyroid (USP); D013963:Thyroid Hormones