THE EFFECT OF CORTICOSTEROIDS ON SERUM SIALYLTRANSFERASE ENZYME-ACTIVITIES IN THE RAT

Previous studies have demonstrated corticosteroid regulation of sialyl transferase (sialyl-T) enzyme activities in a number of different tiss ues throughout the body. In this study we examined the regulatory effe ct of corticosteroids on serum enzyme activity in the rat. The total s erum sialyl-T activity was not affected by a decrease in corticosteroi d levels following adrenalectomy. However, while there was a significa nt increase in enzyme activity following dexamethasone treatment, aldo sterone had no effect on this parameter. Subsequent examination of ind ividual sialyl-T enzymes demonstrated a slight decrease in alpha 2,6 s ialyl-T activity following adrenalectomy which was restored to basal l evels following dexamethasone treatment. The activity of the alpha 2,3 sialyl-T enzyme was not affected by adrenalectomy or dexamethasone tr eatment, 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 seru m sialyltransferase activity in the rat is under the influence of circ ulating corticosteroids. (C) 1998 Elsevier Science B.V.