Corticosterone increases the synthesis of a soluble protein in pituitary glands from adrenalectomized male rats which precipitates with anti-rat growth antiserum

Abstract

The well-documented stimulation of rat growth hormone (rGH) synthesis by corticosterone in rat pituitary GHs cells [l] has proven to be a good experimental system for investigating glucocorticocoid regulation of protein synthesis. However, as there are substantial differences between GHs cells and intact rat pituitary glands, the effect of corticosterone on induction of specific soluble proteins was investigated in intact rat pituitary glands. The methodology of double isotope incorporation and SDS-polyacrylamide gel electrophoresis, successfully used to demonstrate estrogen-induced proteins in the uterus [2] and hypothalamus [3,4], was applied. We report here that treatment of adrenalectomized male rats with corticosterone increases the synthesis of a specific soluble protein with a relative molecular mass (i’kfr) 24 000 on SDS-urea polyacrylamide gels, identical in size to the form of rGH made in GHs cells [5]. The identity of this induced protein with rGH was tested using a specific anti&H antiserum. When pre-labeled pituitary-gland soluble protein was mixed with this antiserum, the 24 000 M,-induced protein was quantitatively precipitated. The precipitation of the corticosterone-induced protein with anti&H antiserum is good evidence that in intact pituitary glands, lie GHs cells, corticosterone increases rGH synthesis.