INSULIN-LIKE GROWTH-FACTOR-I DOES NOT INHIBIT INSULIN-SECRETION IN ADULT HUMAN PANCREATIC-ISLETS IN TISSUE-CULTURE

Insulin-like growth factor I (IGF-I) has been found to increase insuli n sensitivity and suppress insulin secretion, thereby having a potenti al interest as a therapeutic agent for non-insulin-dependent diabetes mellitus (NIDDM), The aim of the present study was to investigate the direct actions of IGF-I (400 ng/ml) on human pancreatic islets, or on rat pancreatic islets, during a 48 h period in tissue culture. Insulin -like growth factor I did not affect medium insulin accumulation, DNA or insulin content or short-term glucose-induced insulin release of hu man islets. However, in rat islets the peptide induced a significant d ecrease in the insulin increase ratio in response to 16,7 mmol/l gluco se. In conclusion, the present data suggest that IGF-I does not direct ly affect the function of human pancreatic beta-cells. If this in vitr o data can be extrapolated to the in vivo situation, it suggests that the observed inhibitory effects of IGF-I on serum insulin levels may b e secondary to peripheral effects of the peptide.