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KMID : 0378019710140010038
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New Medical Journal
1971 Volume.14 No. 1 p.38 ~ p.46
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Studies on the Hepatic Accumulation of the Triglyceride Following the Injection of L-Tryptophan in Albino Rats
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Abstract
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L-Tryptophan is one of the essential amino acids and a component of body protein. The metabolites of tryptophan, niacin, serotonin and tryptamine demonstrated many biochemical, physiologic and pharmaco￢logic roles. Also tryptophan is involved in body metabolism through enzyme induction, gluconeogenesis and enzyme agreggation. In 1966 Kim observed additional effect of tryptophan, namely the accu￢mulation of triglyceride following the injection of tryptophan. "Fatty liver" as defined by the hepatocellular infiltration with fat and the accumulation of triglyceride has been investigated by many workers. Carbon tetrachloride, ethionine, phosphorus, azaserine, ethahol and a choline deficient diet can produce a fatty liver.
The investigation has confirmed the finding of triglyceride accumulation following the injection of tryp￢tophan, and the mechanism of this effect has been studied.
Male albino rats weighing 200-250g, prior to the experiment, have been fed a diet 15% casein for one week. L-Tryptophan 0.34 mMole per rat have been injected intraperitoneally into the intact or adrenalectomized rats. Three hours later the rats have been sacrificed, and the concentration of hepatic
triglyceride, free fatty acid and citrate have been determined.
To study the mechanism of the accumulation of the triglyceride in vivo and in vitro experiments using Warburg´ s apparatus have been carried out. Results are as follows:
1. A single injection of 0. 34 mMole of tryptophan produced hepatic triglyceride accumulation which
appeared by 2. 5 hours after the injection and disappeared after 24 hours.
2. Multiple injections(5 days) of tryptophan increased hepatic triglyceride but only to the same extent
as seen following a single injection. This indicates the phenomenon was only temporal.
3. Only tryptophan among the general amino acids caused an increase in hepatic triglyceride. 4. Results of studies on the mechanism of tryptophan-triglyceride effect;
a) An accumulation of triglyceride was demonstrated in adrenalectomized rats.
b) Following the administration of reserpine the rats were given L-tryptophan, and a subsequent
increase was noted in the hepatic triglyceride.
c) Although L-methionine usually has a lipotropic effect it failled to stop accumulation of trigly￢ceride following tryptophan injection.
d) In Warburg´ s system(in vitro study) using acetate-1-14C tryptophan stimulated lipid biosynthesis in the liver slice.
f) In vivo and in vitro tryptophan increased the amount of citrate in the liver and plasma. Citrate could accelerate the rate of lipid synthesis.
f) There was no difference between the tryptophan treated and the control in the rate of palmitate
-1-14C oxidation.
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