Regulation of growth hormone messenger RNA by thyroid and glucocorticoid hormones.

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Abstract
Thyroid and glucocorticoid hormones stimulate growth hormone [GH] synthesis in cultured rat pituitary cells (GC). Changes in GH production and mRNA were compared in these cells. Triiodothyronine (10 nM) and dexamethasone (1 .mu.M) stimulated increases in GH production by 2.5- and 3.8-fold, respectively. There were corresponding increases in the capacity of RNA from hormone-treated cells to direct synthesis of pregrowth hormone in a wheat germ cell-free translation system, suggesting hormone-regulated increases in GH mRNA. Hormone-induced changes in mRNA were also demonstrated by determining the kinetics of hybridization of a c[cytoplasmic RNA]DNA probe prepared from RNA enriched (about 70%) for GH translational activity with RNA from control and hormone-treated cells. Thyroid and glucocorticoid hormones can probably regulate growth hormone production by influencing the levels of its mRNA. [Horse and fetal calf serum were used].