糖尿病患者における血清Lecithin: Cholesterol Acyltransferase活性

抄録

LCAT is an enzyme catalyzing esterification of cholesterol in plasma by transferring fatty acid from beta-position of lecithin to 3-OH of cholesterol. The enzyme works mainly on plasma lipoproteins. There are several reports describing the plasma level of LCAT is low in the patients with hepatic parenchymal disorders. However, only a few papers have been published concerning the LCAT activities in other pathological conditions.
We measured serum LCAT activities in diabetics by incubating 50 μl of the patient's serum with one ml heated D=1.063 infranatant serum fraction containing 14C cholesterol. After the extractionof lipids with chloroform: methanol, the esterified cholesterol was separated by thin-layer chromatography and the incorporation of radioactivities into the esterified cholesterol was determined, and the esterification was expressed in μg cholesterol estrified per ml per hr.
The results were as follows:
A) No significant correlation was found between the serum LCAT activities and the blood glucose levels. Also there was no significant difference in serum LCAT activities between diabetics and normal controls.
B) Serum LCAT activities of non-treated diabetics had a significant positive correlation to serum cholesterol concentrations.
C) There was a significant positive correlation between the degree of relative obesity and serum LCAT activity in the group of patients whose unesterified cholesterol levels were higher than 65 mg/100 ml, however no significant correlation was found when whole non-treated patients were included.
D) The mean LCAT activities decreased significantly after insulin treatment in comparison with those of pre-treatment. It seems that the low level of LCAT after insulin therapy relates to the metabolic sequences which would be associated with the decrease of serum cholesterol level by insulin administration.