Changes in liver tryptophan and tryptophan pyrrolase activity after administration of salicylate and tryptophan to the rat

doi:10.1016/0006-2952(72)90254-7

Biochemical Pharmacology

Volume 21, Issue 1, 1 January 1972, Pages 97-101

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Abstract

The tryptophan content and tryptophan pyrrolase activity of rat liver were measured after the intraperitoneal administration of a range of doses of l-tryptophan and salicylate. The injection of salicylate increased both the total and the free concentration of tryptophan in the liver. It is suggested that salicylate induces tryptophan pyrrolase by releasing tryptophan from its binding sites on serum and liver proteins.

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Cited by (18)

Inhibition of rat liver tryptophan pyrrolase activity and elevation of brain tryptophan concentration by administration of antidepressants
1981, Biochemical Pharmacology
The apoenzyme activity of rat liver tryptophan pyrrolase is decreased in vitro by 16–100% by concentrations of many antidepressants of 0.01–1 mM. Apo-(tryptophan pyrrolase) activity is also decreased by 37–86% at 2hr after administration of a 10 mg/kg dose of many antidepressants. This inhibition appears to be due to the prevention of the conjugation of the apoenzyme with its cofactor haem. Brain tryptophan concentration is elevated by 19–39% at 3.5 hr after administration of the above dose of antidepressants. Isocarboxazid is the only antidepressant tested that affects neither liver pyrrolase activity nor brain tryptophan concentration. The non-antidepressants chlorpromazine, β-flupenthixol, mefenamic acid and pargyline are also ineffective in both respects. The increase in brain tryptophan concentration caused by administration of mianserin, viloxazine, desipramine or tranylcypromine is associated with an accumulation of tryptophan in the liver and an increased availability of the circulating amino acid to the brain. It is suggested that antidepressants increase brain tryptophan concentration by inhibiting liver tryptophan pyrrolase activity. The results are briefly discussed in relation to the therapeutic effects of the drugs.
Relevance of free tryptophan in serum to tissue tryptophan concentrations
1974, Metabolism
The consumption of a carbohydrate diet by fasted rats is followed by major decreases in serum nonesterified fatty acids (NEFA) and nonalbumin-bound tryptophan (unbound tryptophan), but by increases in serum total tryptophan and brain tryptophan; the tryptophan concentrations of liver and small intestine are unchanged, while that of skeletal muscle falls slightly. The addition of 15% or 30% fat to a protein-carbohydrate diet results in dose-related increases in serum NEFA and serum unbound tryptophan, but no significant changes in serum total tryptophan or brain tryptophan. The observation that diet-induced changes in serum unbound tryptophan does not correlate with brain tryptophan concentrations is independent of the method used to separate free from albumin-bound serum tryptophan. These studies confirm that, in the rat, a major physiologic regulator of the extent to which serum tryptophan binds to albumin is the concentration of NEFA in serum. These studies also provide additional evidence that the concentration of tryptophan in the brain is not necessarily determined by the size of the unbound pool of tryptophan in blood as measured in serum.
Binding of tryptophan to plasma proteins in several species
1973, Comparative Biochemistry and Physiology -- Part B: Biochemistry and
- 1.
  1. The concentration of tryptophan was measured fluorometrically in whole plasma from several species and again after ultrafiltration to remove tryptophan bound to plasma proteins.
- 2.
  2. The major portion of the tryptophan was protein-bound in all of the species, although the degree of binding decreased in the order: dog, rabbit > rat, cat, rhesus monkey > sheep > human > horse > green monkey > marmoset, cow > pig > guinea pig > mouse > turkey > chicken.
- 3.
  3. Thus tryptophan binding to plasma proteins seems to be a characteristic of many warm-blooded animals, and the extent of the binding may have physiologic significance in all of these species.
Tryptophan pyrrolase in rat liver after phenobarbital administration
1973, Toxicology
The administration of phenobarbital increases the activity of tryptophan pyrrolase in the particle-free fraction of rat liver homogenate administration of the drug. The activity of tryptophan pyrrolase remains unaltered after the second day of phenobarbital administration in drinking water given daily until the seventh day. The presence of hematin in the incubation medium increase the specific activity of tryptophan pyrrolase both in the experimental in the control group. The degree of saturation of the enzyme by the heme, however, is higher in the experimental group since its activation in the presence of hematin is lower than in the control group. The presence of phenobarbital in the incubation medium produces a slight inhibitory effect on the activity of tryptophan pyrrolase. Repeated administration of phenobarbital does not increase significantly the induction of tryptophan pyrrolase by hydrocortisone or L-tryptophan.
Serum tryptophan decreased, brain tryptophan increased and brain serotonin synthesis unchanged after probenecid loading
1972, Brain Research
Dietary supplementation with tryptophan increases the plasma concentrations of tryptophan, kynurenine, and melatonin in Yili mares
2023, Animal Production Science

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Changes in liver tryptophan and tryptophan pyrrolase activity after administration of salicylate and tryptophan to the rat

Abstract

J. biol. Chem.

J. biol. Chem.

J. biol. Chem.

J. biol. Chem.