On the mechanism of action of adrenocorticotropic hormone. Stimulation of deoxyribonucleic acid polymerase and thymidine kinase activities in adrenal glands.

Adrenocorticotropic hormone administration to guinea pigs resulted in an increase in the content of DNA of adrenal glands and the stimulation of the incorporation of 3H-thymidine into nuclear DNA thereby indicating an induction of DNA synthesis. The activities of thymidine kinase and DNA polymerase of adrenal glands were concomitantly increased following adrenocorticotropic hormone treatment. The response in time of both enzymes to hormone administration was quite similar. No differences were detected in the properties of DNA polymerase of adrenal glands from adrenocorticotropic hormone-treated and control animals. Hormone treatment resulted in the stimulation of DNA polymerase activity in both the nuclear and supernatant fractions. The DNA polymerase activity of nuclei utilizes preferentially native DNA as the primer, whereas the enzyme activity in the supernatant fraction prefers denatured DNA.