Fluorometric assays of different β-glycosidases in microdissected pancreatic islets from obese-hyperglycemic mice

Abstract

While histochemical staining methods have revealed the presence of β-glucuronidase in the pancreatic islets, they have failed to demonstrate β-galactosidase and β-glucosidase. When a sensitive fluorometric technic was applied to homogenates of microdissected pancreatic islets from obese-hyperglycemic mice, the latter types of enzyme activities were also found. Some kinetic characteristics of the islet β-glycosidases have been described and found to be essentially the same as in the exocrine part. Both β-glucuronidase and β-glucosidase displayed significantly higher activities in the pancreatic islets than in the exocrine pancreas. Wile the β-glucuronidase activity in the islets amounted to 25 per cent of that found in the liver, the endocrine pancreas and the pituitary gland displayed the highest β-glucosidase activity among the tissues studied. The β-galactosidase activity of the islets was only 15 per cent of that found in the exocrine pancreas. The functional significance of the relatively high activities of β-glucuronidase and β-glucosidase in the mouse islets is still obscure. It is reasonable to assume that β-glucuronidase, at least, is located mainly in the insulin-producing β cells.