Glycemia and immunohistochemical changes in the endocrine pancreas of the turtle Chrysemys dorbigni treated with streptozotocin.

The diabetogenic action of streptozotocin (SZ) was investigated in the turtle Chrysemys dorbigni after a 1- or 14-day fast. SZ (130 or 250 mg/kg) was injected intravenously, and blood glucose and plasma insulin were measured. Pancreatic endocrine cells were stained immunohistochemically by the immunoperoxidase avidin-biotin-peroxidase complex method. Only 14% of the SZ-treated turtles showed hyperglycemia. Prolonged fasting did not increase the percentage of hyperglycemic animals. In control turtles, insulin (beta)-, glucagon (alpha)- and somatostatin (delta)-immunoreactive cells were detected in increasing order of frequency. The qualitative changes seen in cells from the hyperglycemic SZ-treated turtles were more evident in beta and delta cells.