Desoxyribonucleic Acid (DNA) Synthesis in the Radiated and Stimulated Thyroid Gland

Abstract

Nuclear changes and DNA synthesis of thyroid cells of rats in early and late post 131I radiation were explored. Tritiated thymidine and radioautography were used to identify nuclei which were synthesizing DNA, and Feulgen staining and microspectrophotometry were used to measure amounts of DNA in individual nuclei. Thiouracil was used as a stimulus. Although obvious destruction of cells with rapid loss of function may not occur, subtle damage is demonstrable by newer methods. Thyroids which retained 1.5–2 μc of a dose of 13lI (2640 rads), when stimulated early after radiation, displayed some transient impairment in capacity for DNA synthesis, followed by a supramaximal response at 2 months. A stimulus at 8 months produced DNA synthesis and increased thyroidal weight comparable to nonradiated glands, but unusual variations in nuclear DNA and volume persisted. Large and sometimes bizarre nuclear forms were usually synthesizing DNA. In contrast, thyroids which retained 15–20 μc (26,400 rads), without obvious ...