Abstract
The purpose of this paper is to study the glycerol metabolism of hypothalamic obese mice and of hereditary obese mice. The glycerokinase [EC 2.7.1.30] activity in the epididymal adipose tissue of goldthioglucose obese mice and of yellow obese mice (Ay/a), fed for 13 weeks (dynamic stage) or for 24 weeks (static stage), was measured by the method of Newsholme modified by Yugari. The plasma immunoreactive insulin (IRI) levels were also measured in these animals and the relationship between plasma IRI and glycerol metabolism was observed. The following results were obtained.
A glycerokinase activity was detected in the epididymal adipose tissue of normal mice. In the dynamic stage of both groups of obese mice, the glycerokinase activity per mg protein was not elevated, but, glycerokinase activity per 105 adipose cells and per epididymal adipose tissue was elevated several times as high as that in their nonobese or lean littermates. Moreover, glycerokinase activity per 105 adipose cells showed positive correlation with plasma IRI. In the static stage, glycerokinase activity was not elevated in either group of obese mice and no correlation was seen between glycerokinase activity per 105 adipose cells and plasma IRI. In the dynamic stage, a remarkable increase of body weight was observed. It is concluded that hyperinsulinemia seems to activate the glycerol metabolism in adipose tissue of obese mice, resulting in the increased triglyceride synthesis and therefore, the development of obesity. In the static stage, hyperinsulinemia was not marked in obese mice, and glycerol metabolism in epididymal adipose tissue seems to be norm alized.
