Chronic depression of serum concentrations of sialic acid in alloxan-induced diabetic rats.

: This study was performed to determine whether alloxan treatment of rats alters concentrations of the terminal carbohydrate residues, L-fucose and sialic acid, of serum glycoproteins. Results indicate that in the uncompensated diabetic rat, chronic depression of serum sialic acid concentration occurred with no apparent alteration in the concentration of L-fucose. The depression in sialic acid concentration may be attributed, in part, to decreased activities of hepatic enzymes involved in sialic acid synthesis similar to those observed by others after treatment of rats with the diabetogenic agent streptozotocin. The lack of any significant alteration in the concentration of L-fucose fails to confirm, in the experimental diabetic rat, the increased protein-bound fucose values reported in human diabetics. Administration of insulin was not effective in modifying the sialic acid response after alloxan treatment.