DECREASED WEIGHT-GAIN IN BB RATS BEFORE THE CLINICAL ONSET OF INSULIN-DEPENDENT DIABETES

Inbred specific pathogen-free diabetes-prone (DP) and diabetes-resista nt (DR) BB rats were crossed to produce F1 and intercrossed to produce F2 rats. Diabetes segregates in these crosses as a recessive trait on rat chromosome 4. The weight gain of genetically diabetes-prone rats born to F1 healthy parents was studied to avoid effects of maternal di abetes. The weight gain of the F2 rats was initially not different fro m the F1 parents. The F2 rats later developing diabetes grew in parall el with their non-affected siblings up until the last 9 days before on set. During these 9 days they showed a decreased weight gain compared to their healthy litter-mates regardless of age. We conclude that decr eased weight gain precedes the abrupt clinical onset of diabetes in BB rats and that it may be due to processes associated with the selectiv e loss of beta cells.