Insulin secretion in glucosamine-induced hyperglycemia in rats

¹ Research Institute, Hospital for Sick Children, and Department of Physiology, University of Toronto, Toronto, Ontario, Canada

The hyperglycemia response produced by the injection of glucosamine in rats has been studied by comparing the effects of equal doses of glucosamine and glucose on blood glucose, circulating insulin, and pancreatic insulin content. The effect of glucosamine and glucose on insulin release from the islets has been studied in vitro by incubating slices of pancreas from normal rats and from rats injected with glucosamine. After glucosamine injection, the blood glucose rose and the circulating insulin decreased. In the glucose-injected group the hyperglycemia was lower and the circulating insulin higher. Insulin output from incubated pancreatic slices of normal rats rose when the glucose concentration in the medium was increased or when tolbutamide was added. A decrease below the base line occurred on the addition of glucosamine or when pancreas slices from glucosamine-injected rats were incubated. Insulin injection decreased the hyperglycemic effect of glucosamine whereas tolbutamide was ineffective. These results suggest that glucosamine exerts an inhibitory effect on insulin release from the pancreas.

Note:
With the Technical Assistance of Lillian Slonevsky

Key Words: pancreas incubation • tolbutamide • insulin release • pancreatic insulin content • circulating insulin

Submitted on September 17, 1964