Studies on the Site and Mechanism of Action of the Growth Inhibiting Effects of Estrogens

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Abstract
The effect of estrogens and growth hormone on the incorporation rate of sulfate into costal cartilage of the mouse was studiedin vivoandin vitroin normal, starving and hypophysectomized animals. Growth hormone was unable to counteract estrogen‐induced inhibition of sulfate incorporationin vivo.Starvation of the mice elicited a depression of sulfate uptakein vivo, but a simultaneous estrogen treatment caused a further decrease in sulfate incorporation in the starving mice. Sulfate incorporation into costal cartilage samplesin vitrowas markedly inhibited in the presence of estrogen in the incubation medium. Costal cartilage samples from hypophysectomized mice incorporated less35S‐sulfate than those from the controls, but estrogen in the medium caused no further decrease in sulfate uptake. Incorporation rates of3H‐acetate and35S‐sulfate were reduced to a similar degree by estrogen in the medium. It is concluded that estrogen‐induced inhibition of growth is neither due to growth hormone deficiency, nor to an appetite diminishing effect of the hormones. Estrogens exert a local inhibitory effect on sulfate (and acetate) incorporation in the chondrocytes and growth stimulation of the cells is a necessary condition for the appearance of the inhibiting actions of estrogens.