Cortisol Inhibits Glycosaminoglycan Synthesis in Cultured Rainbow Trout Cartilage

Abstract

In vitroactions of corticosteroids (cortisol, 11-deoxycortisol, cortisone, and corticosterone) as well as interaction between cortisol and triiodothyronine (T3) or recombinant human insulin-like growth factor-I (rhIGF-I) on cartilage glycosaminoglycan (GAG) synthesis in rainbow trout (Oncorhynchus mykiss) were examined. Uptake of [35S]sulfate by isolated branchial cartilage was measured as a marker for GAG synthesis.In vitroexposure of cartilage to cortisol at concentrations of 10, 100, and 1000 nMfor 6 days dose-dependently inhibited sulfate uptake, while exposure to 0.1 and 1 nMcortisol had no effect. Corticosterone and 11-deoxycortisol at concentrations of 10 and 100 nMinhibited sulfate uptake slightly but not dose-dependently. Cortisone (1, 10, and 100 nM) had no effect. When cortisol (1, 10, and 100 nM) and T3(0.075 and 0.75 nM) were simultaneously added to the culture, the T3-induced sulfate uptake was dose-dependently reduced by the presence of 10 and 100 nMcortisol. 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 nMrhIGF-I was only slightly inhibited by 100 nMcortisol, but 1 nMrhIGF-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 T3and IGF-I, and inhibitory hormones, such as cortisol.