[Histological study of pancreatic islets in hypothalamic obese rats (author's transl)]

It has been considered that hyperinsulinemia is one of the important factors in the development of obesity. With the purpose of investigating the mechanisms of hyperinsulinemia in obese rats induced by hypothalamic lesions (HTL), the time-caused changes in body weight, blood glucose and plasma immunoreactive insulin (IRI) levels in addition to histological changes in the pancreatic islet were studied. The following results were obtained. 1. The development of obesity, a rise of plasma IRI level and an enlargement of pancreatic islets were found in HTL rats. The enlargement of pancreatic islets was directly proportional to body weight, index of obesity and plasma IRI level. 2. The B cells of the pancreatic islets of HTL rats revealed well-developed Golgi apparatus and rough endoplasmic reticulum, and numerous degranulated and pale secretory granules. 3. A number of mixed cells were shown in the periphery of the pancreatic islets of HTL rats. 4. Emiocytotic phenomena of the granular discharge were encountered frequently in the B cells of the pancreatic islets of HTL rats. These histological findings of the B cells in HTL rats well reflected hypersecretion of insulin in this type of obesity.