Direct long-term effect of hydrocortisone on insulin and glucagon release from mouse pancreatic islets in tissue culture.

The effects of glucocorticoids on the pancreatic endocrine function was studied in isolated mouse pancreatic islets maintained in tissue culture for 1 to 3 weeks. Following culture for 2 week without corticoid supplement acute experiments with hydrocortisone showed no significant effect on the glucose-induced insulin release at 10(-8) to 10(-5) mol/l hydrocortisone. When, however, the islets were cultured in the presence of hydrocortisone, there was an increased insulin release to the medium in a dose-dependent manner, with the maximal effect at 10(-7) mol/l hydrocortisone. The release of glucagon to the medium was not affected to the same degree, but showed a slight inhibition at increasing concentrations of hydrocortisone. Short-term experiments after the culture period showed that islets cultured for 3 weeks in the presence of 10(-7) to 10(-5) mol/l hydrocortisone had an enhanced insulin secretion in response to glucose. The islets did not show any statistically significant change in their insulin- and DNA-content after 3 weeks of culture with hydrocortisone, but a marked reduction in the content of hydrocortisone. The present results suggest that physiological concentrations of hydrocortisone are importance for mouse islets to maintain their insulin production in tissue culture.