The effect of corticosteroids on serum sialyltransferase enzyme activities in the rat

Previous studies have demonstrated corticosteroid regulation of sialyltransferase (sialyl-T) enzyme activities in a number of different tissues throughout the body. In this study we examined the regulatory effect of corticosteroids on serum enzyme activity in the rat. The total serum sialyl-T activity was not affected by a decrease in corticosteroid levels following adrenalectomy. However, while there was a significant increase in enzyme activity following dexamethasone treatment, aldosterone had no effect on this parameter. Subsequent examination of individual sialyl-T enzymes demonstrated a slight decrease in alpha 2,6 sialyl-T activity following adrenalectomy which was restored to basal levels following dexamethasone treatment. The activity of the alpha 2,3 sialyl-T enzyme was not affected by adrenalectomy or dexamethasone treatment, but was stimulated significantly by aldosterone. In general, the levels of serum sialoglycoproteins mirrored well the activities of the appropriate sialyl-T enzymes, These results demonstrate that serum sialyltransferase activity in the rat is under the influence of circulating corticosteroids. (C) 1998 Elsevier Science B.V.