Effect of adrenal steroids on bone resorption in rats.
Rats labeled with strontium-85 (85Sr) were rejected with adrenocortical steroids for 2 wk. The urinary-to-tibial (U/T) 85Sr ratio was used as an index of bone resorption. The glucocorticoids caused an inhibition of skeletal resorption, as judged by the 50% reduction in the U/T ratio, and decreased excretion of hydroxyproline. Thyroidal calcitonin levels were slightly elevated in glucocorticoid-treated animals, suggestive of a possible retardation of calcitonin release. The U/T ratios of thyroparathyroidectomized (TPTX) rats injected with corticosteroids were 50% of control values. The results indicate that glucocorticoids inhibit bone resorption independent of the action of calcitonin. Cortisol treatment increased the tibial density as measured by a radiographic technique. However, bone density was decreased and the U/T ratio increased in steroid-treated rats fed a low-calcium diet. In TPTX cortisol-treated rats, parathyroid extract (PTE) increased the U/T ratio and serum calcium but not to the degree observed in TPTX PTE-injected control animals. These experiments indicate that in rats glucocorticoids inhibit the rate of bone resorption but this effect can be overcome in part by PTE.
D000818:Animals; D001835:Body Weight; D001862:Bone Resorption; D002116:Calcitonin / Q000378:metabolism; D002118:Calcium / Q000097:blood; D002136:Calcium, Dietary; D003900:Desoxycorticosterone / Q000494:pharmacology*; D003907:Dexamethasone / Q000494:pharmacology*; D006854:Hydrocortisone / Q000494:pharmacology*; D006909:Hydroxyproline / Q000652:urine; D008297:Male; D010280:Parathyroid Glands / Q000502:physiology; D011859:Radiography; D051381:Rats; D013961:Thyroid Gland / Q000502:physiology; D013977:Tibia / Q000000981:diagnostic imaging; D014020:Tissue Extracts / Q000494:pharmacology
D002136:Calcium, Dietary; D014020:Tissue Extracts; D003900:Desoxycorticosterone; D003907:Dexamethasone; D002116:Calcitonin; D006909:Hydroxyproline; D002118:Calcium; D006854:Hydrocortisone