Characteristics of radiation-induced pituitary-thyroid functional disturbance in relation to pituitary and thyroid tumors in rats. [X radiation]

Technical Report · Thu Jan 01 04:00:00 EST 1976

OSTI ID:7335529

Lu, S T

The acute response of the rat thyroid gland to head-neck x-irradiation at the maximal tumor inductive dose is mainly manifested by a depression of serum thyroxine level. This acute disturbance normalizes within 8 weeks after x-irradiation. In unirradiated animals, thyroid necrotic changes appear that are age related. In head-neck x-irradiated rats, however, such changes show an apparent peak at one week after treatment. Thereafter, it subsides to the level indistinguishable from the controls. Except for an enlarged nucleus that occurs at one year after x-irradiation, no other histologic features can distinguish radiation necrosis from spontaneous necrosis. After x-irradiation, increase and decrease in serum thyrotropin (TSH) level is observed. The TSH elevation is apparently associated with decreased thyroxine. However, rats with TSH depression had a normal thyroxine level. Thus, it is suggested that the set-point of the thyrostat has changed as a result of head-neck x-irradiation. One year after x-irradiation, increased TSH is needed to maintain the thyroxine level in the x-irradiated rats similar to that of controls. At the same time, the thyroid gland was smaller than the controls, although the degree of necrosis was not different from controls. Increased TSH level is maintained in the x-irradiated rats that do not have endocrine neoplasms. Other than medullary carcinoma of the thyroid, the thyroid and/or pituitary neoplasms obliterate the functional aspects of the pituitary-thyroid axis. The results are inconsistent with thyroxine-TSH levels.

• Research Organization: Rochester Univ., N.Y. (USA). School of Medicine and Dentistry
• OSTI ID: 7335529
• Report Number(s): UR-3490-1006
• Country of Publication: United States
• Language: English

Related Subjects

560152* -- Radiation Effects on Animals-- Animals
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMINO ACIDS
ANIMALS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BODY
BODY AREAS
CARBOXYLIC ACIDS
DISEASES
ELECTROMAGNETIC RADIATION
ENDOCRINE GLANDS
GLANDS
HEAD
HORMONES
IONIZING RADIATIONS
MAMMALS
METABOLISM
NECK
NEOPLASMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANS
PEPTIDE HORMONES
PITUITARY GLAND
PITUITARY HORMONES
RADIATION EFFECTS
RADIATIONS
RADIOINDUCTION
RATS
RODENTS
THYROID
THYROID HORMONES
THYROXINE
TSH
VERTEBRATES
X RADIATION