Effects of diabetes and insulin treatment of diabetic rats on hyaluronan and hyaluronectin production in injured aorta

The present study was conducted to determine the effect of diabetes with an d without insulin treatment on the production of hyaluronen (HA) and distri bution of hyaluronectin (HN) in the rat aorta 14 days after injury with a c atheter balloon. Injury increased intima-media wet weight (+11%) and DNA co ntent (+37.5%). This increase was slightly enhanced in untreated diabetic r ats (+14.7% for wet weight and +48.9% for DNA content) and was significantl y greater in diabetic rats treated with insulin (+28.9% for wet weight and +54% for DNA content). HA content increase in the injured aorta of nondiabe tic rats (+43.6%) was similar in untreated diabetic (+44.7%) and more prono unced in diabetic rats treated with insulin (+91.3%). HA was markedly expre ssed in the neointima of nondiabetic rats, particularly near the lumen of t he aorta. In untreated diabetic rats, HA was present throughout the neointi ma and not mainly close to the lumen. HA staining in the neointima of diabe tic rats treated with insulin was similar to that in nondiabetic rats. HN w as strongly expressed throughout the neointima of all groups. injury enhanc ed the production of a high molecular mass HN (>400 kDa); this was not obse rved either in untreated or in insulin-treated diabetic rats. In conclusion , insulin treatment promoted the proliferative response of aorta to injury and this was associated mainly with increased HA production. This finding s uggests that HA, which has been shown to play a crucial role in smooth musc le cell proliferation and migration, may be involved in the promoting effec t of insulin treatment on arterial wall reaction to injury.