[Effect of insulin therapy on abnormal bone and mineral metabolism in chronic streptozotocin-induced diabetic rat].

By use of histomorphometry and photon and physical, calcium homeostasis, bone morphology, bone mass and bone growth were studied in freely fed control, streptozotocin-induced diabetic, long-term and short-term insulin treated diabetic rats 14 weeks after the induction of diabetes. We conclude that untreated chronic streptozotocin-induced diabetic rat could result in abnormal bone and mineral metabolism, which is characterized by hypercalciuria, hyperphosphaturia and hyperphosphatemia, significant bone loss and growth arrest. The extent of bone loss correlated with the duration of the disease process. The anatomical basis of bone mass reduction is the diminution of osteoblasts activity which results in reduction of bone formation and insufficient bone calcification and relative increment of osteoclasts activity. Thus, bone resorption overweight bone formation leading to a negative balance of bone remodeling. The effect of PTH and CT on bone changes in diabetic rats can't be affirmed in our experiments. It is probable that metabolic disorder and/or insulin deficiency has a direct effect on bone changes. Insulin therapy started earlier in the course can prevent and somewhat later can completely normalize the altered skeletal morphology of diabetic rats. Whether this result is due to direct effect of insulin on skeletal tissue or through the correction of metabolic disorder remains to be resolved.