Cortisol inhibits glycosaminoglycan synthesis in cultured rainbow trout cartilage

In vitro actions of corticosteroids (cortisol, 11-deoxycortisol, cortisone, and corticosterone) as well as interaction between cortisol and triiodothyronine (T-3) or recombinant human insulin-like growth factor-I (rhIGF-I) on cartilage glycosaminoglycan (GAG) synthesis in rainbow trout (Oncorhynchus mykiss) were examined. Uptake of [S-35]sulfate by isolated branchial cartilage was measured as a marker for GAG synthesis. In vitro exposure of cartilage to cortisol at concentrations of 10, 100, and 1000 nM for 6 days dose-dependently inhibited sulfate uptake, while exposure to 0.1 and 1 nM cortisol had no effect. Corticosterone and 11-deoxycortisol at concentrations of 10 and 100 nM inhibited sulfate uptake slightly but not dose-dependently. Cortisone (1, 10, and 100 nM) had no effect. When cortisol (1, 10, and 100 nM) and T-3 (0.075 and 0.75 nM) were simultaneously added to the culture, the T-3-induced sulfate uptake was dose-dependently reduced by the presence of 10 and 100 nM cortisol. When cortisol(1, 10, and 100 nM) and rhIGF-I (0.1 and 1 nM) were added together, the sulfate uptake induced by 0.1 nM rhIGF-I was only slightly inhibited by 100 nM cortisol, but 1 nM rhIGF-I completely masked the inhibitory effect of cortisol. These data suggest that GAG synthesis in the rainbow trout cartilage is controlled by multiple interactions among stimulative hormones, such as T-3 and IGF-I, and inhibitory hormones, such as cortisol. (C) 1997 Academic Press.