To determine whether hyperglycemia in the obese hyperglycemic ( ob ob) mouse is related to enhanced activity of the pancreatic beta cell, streptozotocin (175 mg/kg) was injected into lean and ob ob mice at 8 wk of age. The influence of this injection upon glucose metabolism, adipose cellularity, pancreatic morphology and immunoreactive insulin (IRI) release from isolated pancreatic islets was measured. The plasma glucose levels before and after an oral glucose load were elevated in lean and decreased in ob ob mice 2 wk after treatment with streptozotocin. By 5 wk after this treatment, a reduced pancreatic islet size, beta cell number and a decreased pancreatic islet IRI release were present in both lean and ob ob mice. At this time, plasma glucose was still elevated in lean, but depressed in ob ob mice and the insulin responsiveness in muscle and adipocytes was unchanged. Hyperglycemia abates in the ob ob mouse as hypersecretion of insulin is diminished, but these observations may not be directly related, since streptozotocin affects key metabolic activities of the liver as well as the pancreatic beta cell. The progression of obesity and status of adipose cellularity are not directly related to hyperinsulinemia, since they are not altered following streptozotocin treatment.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism