Connective Tissue Macromolecular Changes in Rats with Experimentally Induced Diabetes and Hyperinsulinism

A study of connective tissue components from skin of rats with induced diabetes and hyperinsulinism was performed. Diabetes was induced in rats by a single injection of streptozotocin (50 to 75 mg./kg. body weight) and hyperinsulinism by daily injection of NPH insulin (½ to 2½ U.). Serum was analyzed for protein-bound carbohydrates and free sugars. A decrease in serum protein-bound sugars was observed in the diabetic animals. These slightly increased in hyperinsulin state. Acid mucopolysaccharides (MPS), glycoproteins (GP) and collagen were isolated from skin of experimental animals and compared with the controls. The contents of total MPS and GP decreased in diabetic skin; these increased in hyperinsulin state, similar to that observed in human diabetes. Diabetic rat skin had more soluble collagen, while less soluble collagen was observed in hyperinsulin state. It is suggested from these observations that insulin is a driving force toward the synthesis and accumulation of these compounds in connective tissue in experimental hyperinsulinism and, perhaps, in human diabetes with prolonged insulin treatment.