Natural history of B-cell dysfunction in spontaneously diabetic Chinese hamsters

To elucidate the pathogenesis of diabetes in spontaneously diabetic Chinese hamsters (CHAD strain), a longitudinal study from just after weaning to overt diabetic state was performed. Fasting and non-fasting plasma glucose, non-fasting plasma insulin and pancreatic hormone contents (insulin, glucagon and amylin) were measured, and light microscopic examination of pancreatic islets by immunohistochemical technique and pancreas perfusion study were performed. No insulitis was found in the islets of the CHAD strain. In animals aged 1 month, there was no significant difference in the percentage of B-cell area to islet area between the CHAD strain and the control. At this stage, hyperinsulinemia was observed despite normal plasma glucose levels both in fasting and non-fasting states. In the animals of the CHAD strain aged 2-4 months, insulin secretion from the pancreas, pancreatic insulin content and non-fasting plasma insulin level decreased in proportion to the decrease of B-cell mass. In animals aged about ten months, severe hyperglycemia and hypoinsulinemia were observed. We demonstrated the existence of amylin-like immunoreactivity in the B-cells of Chinese hamsters. However, no amyloid deposit was observed in the islets of the CHAD strain. After the onset of diabetes, amylin secretion from the pancreas and pancreatic amylin content in the CHAD strain were significantly lower than those in the control. We demonstrated the natural history of B-cell dysfunction in the CHAD strain. It could mean the process of B-cell exhaustion. The profile of the CHAD strain is similar to some types of human NIDDM. Therefore, the CHAD strain is a useful diabetic model in the study of NIDDM.