Gelatin 이 가토 insulin 분비에 미치는 실험적 연구

Abstract

[한글]

[영문]

At the present time gelatin is used widely in the dietary control of obesity because of its low calorie content. Studios on rabbits in our laboratory have demonstrated that gelatin has an hyperinsulinemic effect on glucose tolerance, and have led us to investigate possible answers to the following questions.

(1) What is the comlponent of gelatin which causes the development of the hyperinsulinemic glucose tolerance, and how we can illustrate its mechanism.

(2) Are there any quantitative re]ationships between the glucose and insulin levels in the blood of rabbits receiving gelatin is compared with the controls.

In the view of these comsiderations, the present investigation was undertaken to obtain possible answers to the questions. Five experiments were done using 2kg rabbits which had been fed bead curd refuse with fresh vegetables, ad libitum.

In Experiment 1, four groups of experiments were done as follows :

Group 1 : After the animals fasted for 12 hours, a glucose tolerance test (Exton-Rose method) was dose on each normal animal and on adrenalectomized animals.

Group 2: The glucose tolerance test was done with a simultaneous administration of glucose and gelatin.

Gropp 3: The glucose tolerance test was done 2.5 hours. after the administration of 15gm of gelatin in 30ml of water, by stomach tube. The control animals were given 30ml of water.

Group 4: Instead of gelatin, the animals were given an amino arid mixture of gelatin constituent which was equivalent to 15gm of gelatin.

Blood for the measurement of glucose was removed at 0, 30, 60, 90 and 120 minute intervals from a vein of the rabbit's ear Plasma glucose was determined by the Folin-Wu micro metho.

Using the method proposed by C.N. Hales and P.J. Handle, a quantitative radioimmuno astray of the plasma insulin was made. Human insulin and I**125 labelled pig insulin, along with insulin binding reagents, were obtained from the Cen-Cen-Sorin Company in France. A standard calibration curve was prepared.

In Experiment Ⅱ, the animals were given an amino acid mixture of gelatin constituent which was administered in group 4 of experiment 1 by adding .50, 100, 150, 200, 400 and 800 mag of Zn as ZnCl^^2 in 30ml of water, in contrast to another group of animals which were given a single dose of Zn as ZnCl^^2 in 30ml of water.

In Experiment Ⅲ, determination of Zn in gelatin was done using the method proposed by A.S Prasad.

In Experiment Ⅳ, 200 mcg of Zn**65 as ZnCl^^2 was givan in 33ml of water. Blood, liver and pancreas for the measurement of radioactivity was removed at 0, 30, 70,90, 120 and 183 minute intervals immediately after decapitation of the rabbit.

Radioactivity was determined from the sample by using Well-type-crystal scintillation rouster. In order to find but distribution of Zn**65 in the pancreas cell, a radioaudiography was performed on the pancreas, obtained 150 minutes after Zn**65 administratinn.

In Experiment Ⅴ, digestive enzymes, amylase, lipase, trypsinogen and chymotrypsinogen activities of the pancreas, 150 minutes after Zn administration, were determined, It is evident that, as the glucose level in the blood increased, the secretion of insulin Also increased until a plateau was reached 60 minutes

after the administration of glucose. From this 60 minute plateau the insulin ]evel returned to its original value in 60 minutes.

However, the glucose and gelatin were given to the rat at the same time there vas no difference observed in the glucose levels in the gelatin treated rats and the control rats. In remarkable contrast, however, rabbits, given 15gm of gelatin, 150 minutes before being given glucose, showed a 30 minute secretion level of insulin which was twice that of the control animals. This occurred even though the glucose level in the two groups remained the sable over the same interval of time. Thus the effort is due directly to the gelatin. However, the effect is not rue to the amino acid constituent of gelatin, but due to Zn which is a constituent of gelatin, because this fact was also true when 200mcg. of ZnCl^^2 were given instead of gelatin. Meanwhile no remarkable differences were observed in the glucose levels

between the group ZnCl^^2 with glucose and the gelatin treated group.

Low concentration of Zn (50-100 Mcg) does not seem to be responsible, on the other hand a high concentration (400-800mcg) of Zn inhibits the secretion of insulin. The responsible concentration of Zn being 150-200mcg: for secretion of insulin. The Zn content of gelatin averaged 110 meg. per gm of gelatin.

C.P.M. of Zn**65 in plasma, after administration of Zn**65 was increased up to 90 minutes, then a saturated phenomena was observed. However, a continuous increase of C.P.M. of Zn was shown in the liver and pancreatic tissue, witha little more rapid

rate of uptake in liver than in pancreatic tissue. It was confirmed that the Zn**65 was mainly localized in the α-cells of the pancreas. The digestive enzyme activity was not affected at all. We had a postulate as to which component of gelatin was

responsible fur the secretion of insulin, and the results partially confirmed the postulate that glucose, insulin and Zn levels, in cellular process, were related.