Glucocorticoid inhibition of protein synthesis in vivo and in vitro.

In young adult rats receiving glucocorticoids in pharmacological amounts, the accumulation proteins in the liver was suppressed. In vivo pulse-labeling experiments showed that inhibition of protein synthesis in the liver was an early effect of a single dose of glucocorticoid followed by a stimulation of protein synthesis. In animals receiving multiple doses of glucocorticoid over a period of a few days, a more pronounced inhibition in protein synthesis was observed, and the secondary stimulation of protein synthesis did not occur. These in vivo observations were paralleled by the results with cell-free protein-synthesizing systems, which indicated that the glucocorticoid inhibitory effect was imparted to the soluble fraction of the liver.