Assessment of pancreatic islet-cell population in the hyperglycemic athymic nude mouse: immunohistochemical, ultrastructural, and hormonal studies.

: Previous studies in diabetic animal models have demonstrated altered pancreatic islet-cell populations. To further characterize the diabetic syndrome in our athymic nude mouse colony, we studied the population of endocrine cells in pancreatic islets of 4-week-old normoglycemic and 8-week-old hyperglycemic athymic nude (nu/nu) mice using immunohistochemistry, morphometry, and electron microscopy. In normoglycemic 4-week athymic nu/nu mice, the proportions of B (insulin-secreting) cells and A (glucagon-secreting) cells were similar to those in control Balb/c mice; however, the D (somatostatin-secreting) cells were significantly decreased in nu/nu mice. The populations of B and A cells appeared to be normal in hyperglycemic 8-week-old nu/nu mice while there was a significant increase in the proportion of D cells when compared with the proportion in Balb/c mice. Electron microscopic studies indicated that the appearance of B and A cells was similar in the 8-week-old hyperglycemic nu/nu and in controls; however, the D cells appeared to be enlarged and were finely packed with electron-dense secretory granules. Radioimmunoassays of the pancreatic content (micrograms/g fresh pancreas) of insulin, glucagon, and somatostatin in pancreata in 8-week-old normal Balb/c and hyperglycemic athymic nude mice were similar; however, the somatostatin content was significantly increased in the 8-week-old hyperglycemic nu/nu mice compared with age and sex-matched controls. These results demonstrate an altered D cell population and an increase in somatostatin levels in the pancreatic islets of the hyperglycemic athymic nude mouse animal model.(ABSTRACT TRUNCATED AT 250 WORDS)