Pancreatic beta cell replication induced by glucocorticoids in subhuman primates.

Pancreatic islets were studied by means of light microsocpy, autoradiography and electron microscopy in untreated Macaca cyclopis monkeys and after the administration of large quantities of adrenal glucocorticoids. Mild hyperglycemia and profound elevations of serum immunoreactive insulin were induced by glucocorticoid injections of 1 to 3 weeks duration, with a gradual return to pretreatment levels within 2 months after cessation of treatment. Morphologic alterations included degranulation and hyperplasia of pancreatic beta cells. These were noted in association with increased numbers of labeled islet cells after the administration of (3)H-thymidine and beta cells undergoing mitotic division, and could be correlated directly with the magnitude of serum insulin elevation. Evidence of acinar-islet or duct-islet cell transformation was absent. Beta cell regranulation and the twofold increase in extractable pancreatic insulin which followed the cessation of injections demonstrated the survival and functional integrity of the newly formed beta cells.