Abstract
Streptozotocin (STZ), drug used to treat for pancreatic endocrine tumors, is known to specifically impair B cells in the pancreatic islets of Langerhans (referred to here after as “islets”) with a diabetogenic effect. In this study, a immunocytochemistry and electron microscopy were used to morphologically analyze the onset and progression of islet (mainly B cell) injury induced by STZ. Islet B cell injury could be detected by electron microscopical level two hours after administration of STZ, and by light microscopy after three hours. Positive findings using the TUNEL method began to appear six hours after, when the pancreatic islet injury induced by STZ appeared to involve both necrotic and apoptotic processes. At 72hours, the number of endocrine cells in the islets was markedly increased, although these cells were immunocytochemically negative for any islet hormones, and appeared immature with only a few secretory granules detectable. After two weeks, the endocrine islets were completely recovered. Thus, regenerated B-cells appear to be derived from new endocrine cells, acting like an endocrine stem cell.
