Hepatic Enzyme Activities of Glycolysis and Gluconeogenesis in Diabetes of Man and Laboratory Animals[*] [**]

Abstract

In spontaneous diabetes of man and some laboratory animals and in experimental diabetes of rats hepatic enzyme activities of glycolysis (glucokinase, hexokinase, phosphofructokinase, pyruvatekinase) and gluconeogenesis (glucose-6-phosphatase, fructose-diphosphatase) were studied. Aldolase was also assayed as example of a bifunctional enzyme.

In acute streptozotocin diabetes in rats, as well as in ketotic diabetes in spiny mice and in juvenile type diabetes in man, a decrease in the activities of glucokinase, phosphofructokinase and pyruvatekinase and an increase in the activities of gluconeogenic enzymes was observed. These changes must be related to insulin deficiency.

In spontaneous nonketotic diabetes in spiny mice, obesehyperglycemic Bar Harbor, mice and New Zealand Obese (NZO) mice as well as in human maturity onset diabetes, a significant increase of glucokinase activity was found. This corresponds well with the hyperinsulinemia and demonstrates that the liver tissue is insulin sensitive in these types of diabetes. An elevation of activities of gluconeogenic enzymes in nonketotic types of diabetes occurred only in more severe stages of diabetes. According to these studies it seems to be justified, that - at least with regard to hepatic enzyme activities - the alloxan- or streptozotocin-diabetes of the rat may be used as a model for the human juvenile type diabetes, whereas the spontaneous nonketotic type diabetes of some laboratory animals may be used as a model for human maturity onset diabetes.

Key words

Hepatic Enzyme Activities - Streptozotocin Diabetes - Juvenile Diabetes - Maturity Onset Diabetes - Hyperinsulinemia - Insulin Resistance of the Liver

1 Supported by the Deutsche Forschungsgemeinschaft

2 Part of this has been presented at the 5th meeting of the European Association for the Study of Diabetes, September16-18, 1969, Montpellier, France, and at the Second Brook Lodge Workshop on Spontaneous Diabetes in Laboratory Animals, November 6-8, 1969, Brook Lodge, Augusta, Michigan, USA

1 Supported by the Deutsche Forschungsgemeinschaft

2 Part of this has been presented at the 5th meeting of the European Association for the Study of Diabetes, September16-18, 1969, Montpellier, France, and at the Second Brook Lodge Workshop on Spontaneous Diabetes in Laboratory Animals, November 6-8, 1969, Brook Lodge, Augusta, Michigan, USA