Relationship between the histopathology of the endocrine-exocrine pancreas parenchyma and beta-cell function in the Chinese hamster CHIG/Han subline.

To investigate pancreatic histopathology in relation to islet function in type 2 diabetes, pancreatic tissue was examined at disease onset and after death in the genetically diabetic Chinese hamster CHIG/Han subline. The pancreatic islets displayed vacuolation, intraislet fibrosis, variable stages of degranulation, and beta-cell necrosis, but no insulitis. These lesions were associated with changes in immunostaining of major islet peptides, impaired glucose-stimulated (10 mM) insulin secretion, reduced islet insulin content, and the severity of hyperglycemia. The exocrine pancreas was characterized by peri- and intrapancreatic fat and mononuclear cell infiltration. Biopsy of the pancreas had a marked effect on plasma glucose such that at 2 weeks after excision, in 9 and 18% of the severely hyperglycemic hamsters, plasma glucose levels decreased to <7.2 and 15 mM, respectively, and 45% of the mildly hyperglycemic hamsters became transiently normoglycemic (<7.2 mM). The results showed that insulitis is not involved in beta-cell failure of diabetic CHIG/Han hamsters. Vacuolation of islets was the most prominent lesion associated with a functional islet abnormality and development of hyperglycemia. Attenuation of hyperglycemia after biopsy suggests that the pancreas, in type 2 diabetes, maintains the ability to respond to impairment with amelioration of the diabetic state.