Temporal changes in pancreatic islet composition in C57BL/6J-db/db (diabetes) mice.
Temporal changes in non-B cell populations were determined during the period of B cell hyperplasia in diabetes-resistant C57BL/6J mice. Pancreases from normal and db/db mice between 3 and 20 weeks of age were stained immunocytochemically for glucagon, somatostatin and pancreatic polypeptide (PP), and changes in A, D and PP cell volume densities quantified by image analysis. Further, islet volumes, D cell volumes and actual D cell numbers per islet were determined by analysis of serial sections through entire islets. The volume of db/db islets was three- and ten-fold elevated above normal by 8 and 20 weeks, respectively, due mainly to B cell hyperplasia. D cell volume density exhibited a transient increase during the initial phase of B cell hyperplasia, but then showed a gradual reduction; the average number and absolute volume of D cells per islet was comparable in db/db and normal islets from older mice. In contrast, PP cell volume density remained stable throughout, suggesting that this cell type kept pace with B cell hyperplasia. A cells showed a reduced volume density throughout and were distinguished from other islet cells which all responded positively to a degree, albeit non-coordinately, to the mitogenic stimulus exerted by db gene expression. The finding that A cells shared with certain neuroectodermally-derived cell types a differentially high concentration of sn-glycerol-3-phosphate dehydrogenase further underscored the uniqueness of the A cell from other cell types.
D000375:Aging; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000473:pathology*; D005260:Female; D006965:Hyperplasia; D007113:Immunity, Innate; D007515:Islets of Langerhans / Q000254:growth & development / Q000473:pathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D013045:Species Specificity; D013997:Time Factors