Obesity and diabetes mellitus with striking congenital hyperplasia of the islets of langerhans in spiny mice (Acomys Cahirinus) : I. Histological findings and preliminary metabolic observations.

Spiny mice (Acomys) are a group of small rodents indigenous to the Eastern Mediterranean and Africa. The Acomys Cahirinus strain reported on here is indigenous to Israel. The strain is characterized by striking and congenital hyperplasia of the islets of Langerhans, primarily of the beta cells. The endocrine tissue contributes up to 15 per cent of the pancreatic mass in adults, up to 25 per cent in the newborn. Pancreatic insulin content may be as high as 100 units per gram wet weight. When fedad libitum in the laboratory approximately one-half of the animals become obese, while approximately 15 per cent develop a diabetes mellitus-like state with moderate hyperglycemia, glucosuria, and, less frequently, ketonuria accompanied by weight loss and, ultimately, death. The development of the diabetic state is associated with degranulation and, later, striking glycogenic degeneration of the beta cells of the islets of Langerhans. There is also severe glycogenic nephrosis and myocardosis and preliminary observations suggest the presence of thickening of the capillary basement membrane of the renal glomeruli and in the endocrine pancreas. The interrelationships of hyperplasia of the islets of Langerhans, obesity, and diabetes mellitus are as yet to be established, as are the genetic characteristics of each of these entities. An important area of potential usefulness derives from the degree of the hyperplasia of the endocrine tissue, since this should greatly facilitate ultrastructural studies, microdissection and transplantation, as well as organ or tissue culture work. Also, the association of anomalies observed in these spiny mice may, through their systematic study, provide clues for the study of the association of diabetes and obesity with relative hyperinsulinism in man.