The Effects of Growth Hormone on DNA Polymerase Activity in the Liver of Normal and Hypophysectomized Rats

Abstract

DNA polymerase activity has been measured in sham—operated control and hypophysectomized rats, both with and without bovine growth hormone treatment for short and long periods of time. Enzyme activity using denatured primer was consistently decreased in the hormone deficient animals whereas activity using native primer varied with the reference unit employed; activity was increased per mg of supernatant protein, decreased per mg of DNA, and unchanged per milligram of tissue protein. After short—term growth hormone treatment enzyme activity increased proportionally by greater amounts in the livers of the hypophysectomized than of the control rats. In addition, hypophysectomized and control rats showed a different time pattern of peak enzyme response. After long—term treatment enzyme activity remained significantly increased in both the hypophysectomized and control rats. Again the increased enzyme activity was much greater in the hormone deficient animals. In both treatment groups, these increases were generally higher with denatured DNA primer. (Endocrinology92: 194, 1973)