EFFECTS OF GROWTH HORMONE AND CORTICOSTEROIDS ON S35FIXATION IN CARTILAGE

Publisher Website
Google Scholar
Abstract
Previous studies on the effect of growth hormone on S35 fixation in cartilage have been extended to learn more about this reaction and to apply it as a possible assay for growth hormone. It had been noted that increased dosages of growth hormone were accompanied by increased levels of S35 incorporated into costal cartilage of the hypophysectomized rat. The duration of treatment necessary to produce a significant stimulation in S35 uptake was 48 hours. Results after four days of treatment were nearly maximal. The effective biological life of circulating growth hormone as measured by the incorporation of S35 in cartilage is from 24 to 48 hours. The disappearance curve reflecting the metabolic activity of S35 containing compounds in cartilage closely approximates the previously reported half-life of radiochondroitin sulfate, that is, seventeen days. The use of human serum as a vehicle for growth hormone produces no modification of its action, while the use of ten percent gelatin as a vehicle results in a slight decrease in S35 binding. The subcutaneous route of administration of the hormone is as effective as the intraperitoneal route. Hydrocortisone inhibits S35 fixation to about one half of the level noted in control animals. Hydrocortisone also inhibits the stimulatory action of growth hormone, and conversely growth hormone antagonizes the action of hydrocortisone. Cortisone and 9-fluohydrocortisone behave similarly to hydrocortisone in reducing S35 incorporation into cartilage and in reducing the increase in body. weight. Hydrocortisone hcmi-succinatc and tctrahydrocortisone had no notable effect on these processes.