Concentrated Loss of Insulin Secretion in Wistar Rats with Normal Glucose Tolerance

Summary

Rats with decreased insulin response and with normal glucose tolerance were concentrated by repeated selective breeding of normal Wistar rats with low insulinogenic index. In general, the mean insulinogenic index of the inbred offsprings showed a tendency to decrease more than their parents generation. Thus mean insulinogenic indices in second (F₂), third (F₃) and fourth (F₄) generations were significantly reduced more than the normal rats without glucose intolerance. Pancreatic islets from the F₃ and F₄ rats lost partially their ability to release insulin at 20 mM glucose in vitro. It is suggested that a defect responsible for the decreased insulin response in the F₂, F₃ and F₄ rats resulted from a loss of the ability to secrete insulin in each islet, and that this defect was concentrated by repeated selective breeding of normal Wistar rats.

Key-Words:

Selective Breeding - Glucose Tolerance - Insulin Response - Perifused Islets - Rat