Urinary Excretion Of Tryptophan Metabolites Research Articles

162 URINARY EXCRETION OF KYNURENINE AND MELATONIN METABOLITES OF TRYPTOPHAN IN CONVULSIVE DISORDERS IN CHILDREN

INTRODUCTION: In the present paper, we study the urinary excretion of tryptophan metabolites, in both the kynurenine and melatonin pathways in pediatrics patients with febrile and epileptic convulsions. MATERIAL AND METHODS: The patients were classified as follows: GC (Control group, n = 39); FCG (Febrile convulsion group, n = 51); ECG (Epileptic convulsion group, n = 28). Taking into account the existence of a circadian rhythm in melatonin secretion, the groups were further divided into two subgroups (Day (9.00-21.00)/Night (21.00-9.00). Melatonin was measured by RIA, while urine metabolites were measured by thin-layer chromatography. Statistical analyses included a two way ANOVA and comparison of the results. ABREVIATIONS: KYN: L-Kynurenine, 3-OHA: 3-OH-anthranilic, AX: xanturenic acid, OH-K: 3-OH-Kynurenine, AK: Kynurenic Acid, aMT: Melatonin, Trp: tryptophan. CONCLUSIONS: 1.- Normal children showed a circadian variation in patterns of elimination of some of metabolites of tryptophan via the kynurenin pathway and a close correlation between theese and methoxy - indoles pathway. 3.- In the presence of convulsive crises this correlation disappears enterely probably because of the need to cover more demanding biological requirements and clearly modify the pattern of elimination of some Trp metabolites.

Tryptophan metabolism in vitamin B6-deficient mice

Vitamin B6 deficiency was induced in mice by maintenance for 4 weeks on a vitamin B6-free diet. Tryptophan metabolism was assessed by determining the urinary excretion of tryptophan metabolites, the metabolism of [14C]tryptophan in vivo and the formation of tryptophan and niacin metabolites by isolated hepatocytes. The vitamin B6-deficient animals excreted more xanthurenic acid and 3-hydroxykynurenine, and less of the niacin metabolites N1-methyl nicotinamide and methyl-2-pyridone-4-carboxamide, than did control animals maintained on the same diet supplemented with 5 mg vitamin B6/kg. After intraperitoneal injection of [14C]tryptophan, vitamin B6-deficient mice showed lower liberation of 14CO2 from [methylene-14C]tryptophan and [U-14C]tryptophan than did controls, indicating impairment of kynureninase (EC 3.7.1.3) activity. There was no difference between the two groups of animals in the metabolism of [ring-2-14C]tryptophan. Hepatocytes isolated from the vitamin B6-deficient animals formed more 3-hydroxykynurenine and xanthurenic acid than did cells from control animals, but also formed more NADP and free niacin.

Increased urinary excretion of tryptophan metabolites in rats exposed to nitrogen dioxide.

Nitrogen dioxide (NO 2) is widely distributed in nature, and human exposure to it is extensive. It is abundant in all burnt organic materials, including automobile exhaust and cigarette smoke. In the lung of animals exposed to NOo, some subtle changes will occur and they include inflammation (Gardner et al. 1969), emphysema (Freeman and Haydon 1964) and reduced phagocytic or bactericidal activity of the alveolar macrophages (Suzuki et ai.1986). In epidemiological study, Yanagisawa et al. (1986) reported the increased urinary hydroxyproline excretion of residents living in areas of high NO 2 levels. Moreover, in experimental study using animals, exposure to NO o induced the alteration of collagen synthesis and/or ~ degradation in lung (Kleinerman 1979) and accelerated collagen degradation in lung by NOo exposure was responsible for the increase in the excretion of urinary hydroxyproline (Kosmider et al. 1973). From these findings on the increased excretion of urinary hydroxyproline by NO2, Yanagisawa et al. (1986) suggest that urinary hydroxyproline could be used as a personal biochemical indicator of the effects of NO 2 on human health prior to manifestation of respiratory symptoms. Moreover, Ripperton and Johnston (1959) reported that urinary content of aspartic acid increased in rats exposed to NO 9. Exposure to NO 2 may influence the metabolism of amin8 acids to induce their excessive urinary excretion. Since the maximum permissible limit for NOo in working environments in Japan is 5 ppm, in this wo2k, we have studied the changes of urinary excretion of tryptophan metabolites in rats exposed to 5 ppm NO 2 in order to find a new urinary biochemical indicator of the effects of NO 2 exposure on human health.

Effects of fasting on the blood NAD level, and urinary excretion of 5-hydroxyindole-3-acetic acid, and nicotinamide and its metabolites in rats.

The effects of fasting on the blood NAD level, and the urinary excretion of tryptophan metabolites, such as 5-hydroxyindole-3-acetic acid (5-HIAA), nicotinamide, N1-methylnicotinamide (MNA), N1-methyl-2-pyridone-5-carboxamide (2-py) and N1-methyl-4-pyridone-3-carboxamide (4-py), in rats were investigated. Rats, weighing about 430 g, were fasted for 5 days. The body weight loss during the fasting period was about 10 g per day. The blood NAD levels during the fasting period did not decrease compared with the values during the feeding period. The urinary excretion of 5-HIAA abruptly decreased by about 1/2 on day 1 of fasting, compared with the value during the feeding period, and then remained constant. The level of urinary excretion of nicotinamide during the fasting period was almost the same as the value during the feeding peiod. However, the urinary excretion of nicotinamide metabolites, such as MNA, 2-py and 4-py, gradually decreased with the fasting time and the values had decreased by 1/2-1/3 on day 3 of fasting, compared with the values during the fasting period, and then remained constant. On the basis of these findings, the tryptophan metabolism during the fasting period was discussed.

The effects of oestrogen administration on tryptophan metabolism in rats and in menopausal women receiving hormone replacement therapy

The effects of the administration of oestrogens on the activity of hepatic tryptophan oxygenase have been assessed both directly (by measurement of enzyme activity in vitro) and indirectly (by measurement of urinary excretion of tryptophan metabolites) in rats, and indirectly in menopausal women receiving hormone replacement therapy. Intraperitoneal administration of 500 μg of oestradiol or ethinyl oestradiol/kg body wt had no effect on the activity of tryptophan oxygenase in homogenates of liver from mature (13-week-old) female rats. Both adrenalectomy and ovariectomy led to a reduction in the activity of tryptophan oxygenase in homogenates of liver from mature rats; again there was no effect of giving 500 μg of oestradiol/kg body wt by intraperitoneal injection. Intraperitoneal administration of 210 μg of oestrone sulphate/kg body wt for 1 or 2 days before killing, or its incorporation in the diet for up to 8 weeks at an equivalent dose rate, had no effect on the activity of tryptophan oxygenase in homogenates of liver from ovariectomized 6–14-week-old female rats. Intraperitoneal administration of 500 μg oestradiol/kg body wt to intact mature female rats together with 500 mg tryptophan/kg body wt caused a reduction in the urinary excretion of xanthurenic and kynurenic acids, kynurenine and N 1-methyl nicotinamide. When peri- and post-menopausal women were treated with ethinyl oestradiol (20 μg/day) or piperazine oestrone sulphate (3 mg/day) for 3 months, there was an increase in the concn of tryptophan in plasma, with no change in the urinary excretion of xanthurenic and kynurenic acids and kynurenine. This study provides no evidence for the induction of tryptophan oxygenase by oestrogens in rats or human beings.

Effects of benserazide, carbidopa and isoniazid administration on tryptophan-nicotinamide nucleotide metabolism in the rat

Weanling rats were maintained on a diet providing marginally adequate amounts of nicotinamide and vitamin B 6, with a considerable excess of tryptophan to allow endogenous synthesis of nicotinamide nucleotides. Groups of animals received Benserazide or Carbidopa at 0.9 mg/kg body wt/day or isoniazid at 1.3 mg/kg body wt/day. All three drugs led to a reduction in the excretion of N 1-methyl nicotinamide (the principal metabolite of nicotinamide nucleotides in the rat) after 2 and 3 days, compared with control animals receiving the same diet. After 7 days, excretion of this metabolite had returned to the control level. All three drugs are potent inhibitors of tryptophan oxygenase, kynureninase and 3-hydroxyanthranilate oxidase, but the effects of administration in vivo were not related to the apparent K i, values determined in vitro. All three drugs also caused an increase in the activity of nicotinamide deamidase, which may lead to increased efficiency of utilization of dietary nicotinamide in response to deficiency, and hence explain the recovery in N 1-methyl nicotinamide excretion towards the end of the experiment. Urinary excretion of tryptophan metabolites (xanthurenic and kynurenic acids and kynurenine) was not as expected. Benserazide and Carbidopa had no significant effect, while isoniazid caused an increase in kynurenine excretion and a decrease in xanthurenic acid excretion. It is suggested that this may be due to a reduced activity of kynurenine hydroxylase, although isoniazid had no effect on the activity of this enzyme after administration for 11 days, or when added in vitro. The results are discussed in relation to the mechanisms of isoniazid-induced pellagra and Benserazide and Carbidopa-induced niacin depletion in man.

A new aspect of the urinary excretion of tryptophan metabolites in patients with cancer of the bladder.

AbstractMetabolites of the amino acid tryptophan have been suspected of being involved in the genesis of human urinary bladder cancer. It was suggested that a neoplastic change could result from increased urinary excretion of tryptophan metabolites. From studies in which the excretion of metabolites was assessed after loading the patients with L‐tryptophan it was concluded that abnormalities in tryptophan metabolism are causing the elevation of metabolite excretion. The present study however, which measured basal excretion of metabolites, demonstrates that the presence of tumor in the urinary tract must be considered as causative for elevations of metabolite excretion. An improved method for determining the spontaneous metabolite excretion is described. The metabolites kynurenine, kynurenic acid, 3‐hydroxykynurenine, xanthurenic acid and 3‐hydroxyanthranilic acid were determined in 165 urine samples obtained from bladder cancer patients, renal cancer patients, patients cured of bladder cancer and control subjects. Thirty six percent of the bladder cancer patients and 67% of the renal carcinoma patients excreted abnormally high amounts of at least one of the metabolites. It was observed that in bladder cancer an elevated excretion of metabolites occurred principally in patients with obstruction to the outflow of urine from the kidneys. Ureteral obstruction, probably a direct consequence of the presence of tumor in the urinary tract, causes an alteration in renal function which is reflected in urea and creatinine retention. The high incidence of abnormal excretion of tryptophan metabolites in renal cancer also points to alterations in renal function caused by the presence of tumor.

Experimental biharzial bladder cancer: tryptophan metabolism in nonhuman primates experimentally infected with Schistosoma haematobium.

A nonhuman primate species infected with Schistosoma haematobium provided a model system for controlled studies on biharzial bladder cancer. Urinary excretion of tryptophan metabolites by capuchin monkeys (Cebus apella) was similar to that of humans when expressed per g creatinine. Liver tryptophan oxygenase activity of the capuchin monkeys was comparable to that of humans. Excretion of 3-hydroxykynurenine and 3-hydroxyanthranilic acid was elevated above control levels in capuchin monkeys infected experimentally with S. haematobium. The capuchin-S. haematobium system closely resembles the human biharziasis system and offers a reproducible laboratory model system for the controlled study of the parasitology, pathogenesis, and biochemistry of biharzial bladder cancer.

Influence of Riboflavin on Disturbances in Tryptophan Metabolism and Hepatoma Production After a Single Dose of Aflatoxin B 1

Female Wistar rats were given a single oral dose of aflatoxin B1, either alone or with a large amount of riboflavin. Biochemical and histologic studies were performed for 30 months. Nine animals of 19 in the aflatoxin-treated group and only 5 of 18 in the riboflavin-aflatoxin-treated group developed hepatomas. The number of rats was insufficient for tests of statistical significance to be fruitful. Urinary excretion of tryptophan metabolites was studied in aflatoxin- and riboflavin-treated rats after an oral administration of 10 mg tryptophan/100 g rat. Riboflavin did not affect the percentage of aflatoxin-treated animals with abnormal urinary excretion patterns, but did increase the magnitude of the disturbances in elimination of kynurenic and xanthurenic acids. The hepatic tryptophan-oxygenase activity was increased only in the two groups given riboflavin, and the levels of nucleic acids were the same in all groups.

Urinary excretion of tryptophan metabolites during phototherapy

PREVIOUS STUDIES in animals have d e m o n s t r a t e d that, under intense illumination, the transmission of light through living tissue takes place at a degree which causes the occurrence of photochemical reactions) It is known, in fact, that light exposure causes a decrease in blood riboflavin level. 2 Since this vitamin is involved in tryptophan metabolism, participating in the transformation of kynurenine into 3-hydroxykynurenine, 3,4 we have investigated the effects of light on the tryptophankynurenine metabolic pathway in a group of full-term hyperbil i rubinemic newborn infants treated with light exposure. Studies on the ur inary excre t ion of 5 -hyd roxy in dolacetic acid, which is the major metabolite of serotonin and which is derived from the t ryptophan-serotonin metabo l ic pa thway, have not demons t r a t ed any apprec iable changes dur ing the pho to the rapy of lowb i r th -we igh t infants when compared to un i r r ad ia t ed cont ro l subjec ts , imply ing that the p roduc t ion and Catabolism of se ro ton in in the two groups was the Same. 5 In addition the authors did not find any correlat ion be tween the dai ly excre t ion of 5 -hyd roxy in dolacet ic acid and bi r th weight , ges ta t ional age, or serum bilirubin concentration. 5

Tryptophan metabolism and corticosteroids in breast cancer.

Urinary excretion of tryptophan metabolites, free cortisol, and corticosteroid sulfates, and plasma cortisol were determined in 30 breast cancer patients. Although, as a group, the patients with abnormal tryptophan metabolism excreted significantly higher levels of both free cortisol and corticosteroid sulfates than those with normal metabolism, there was no good correlation between urinary tryptophan metabolite excretion and the corticoids. Abnormal tryptophan metabolism was not accompanied by a high plasma cortisol. Patients with widespread metastases had elevated tryptophan metabolite excretions compared to those with early breast cancer or local recurrence, but the two groups did not differ in their plasma or urinary corticosteroid levels. It is concluded that increased adrenocorticosteroid secretion due to stress is not a major factor in producing abnormal tryptophan metabolism in breast cancer.

Effect of Copper Status on the Urinary Excretion of Tryptophan Metabolites and Amino Acids by the Rat

The effect of dietary copper on selected metabolic systems requiring pyridoxal phosphate was investigated by comparing certain urinary excretory products of pair-fed copper-deficient and copper-adequate rats. Kynurenic acid and xanthurenic acid, two tryptophan metabolites, were in lower concentrations in the urines of the copper-deficient animals in the pretryptophan-load period. Following a tryptophan load, these metabolites increased markedly in the urines of both groups, but the in crements were much larger for the copper-deficient animals. The increases in kynurenic acid were greater than those of xanthurenic acid in both groups, but the increase was disproportionately higher in the copper-deficient rats. The excretion of taurine and urea by the copper-deficient rats was significantly less. At the dilution used, several amino acids were found in significant amounts in the urines of the copper-deficient animals, whereas only taurine was detected in the urines of those fed copper. Several possible explanations of these findings are discussed. J. Nutr. 103: 1764-1771, 1973. INDEXING KEYWORDS urinary amino acids •ure copper deficiency •urinary tryptophan metabolites

The influence of simultaneous administration of vitamin B 6 and nicotinamide on tryptophan metabolism in Hodgkin's disease

The urinary excretion of tryptophan metabolites was studied in 10 patients with Hodgkin's disease after tryptophan loading with or without simultaneous administration of vitamin B 6 and nicotinamide. The treatment of these two vitamins corrected completely the abnormal excretory picture (from 23.6% to 7.9%), but with transitory influence. These data show the existence in Hodgkin's disease of a failure of two groups of enzymic systems, one B 6-dependent and the other nicotinamide-dependent.

Oral contraceptives and tryptophan metabolism: effects of oestrogen in low dose combined with a progestagen and of a low-dose progestagen (megestrol acetate) given alone.

The effect upon tryptophan metabolism of the use of combined oestrogen-progestagen oral contraceptives containing a low (0.05 mg) dose of oestrogen, or of the continuous administration of megestrol acetate, has been studied by determining the excretion of tryptophan metabolites in urine collected after a 2 g oral dose of the amino acid. An investigation of 10 women before being given oral contraceptives and after 21 days and three months of their use showed that xanthurenic acid excretion is increased within 21 days and that by three months the urinary levels of xanthurenic acid, kynurenine, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid may all be elevated. Ten other women studied after taking a combined type of oral contraceptive for six months or longer excreted significantly higher levels of all four metabolites than did those who had been treated with these steroids for only three months. The abnormal urinary excretion of tryptophan metabolites was completely reversed by treatment with pyridoxine hydrochloride, 20 mg daily for one month. Studies of four women when they were taking an oestrogen-containing oral contraceptive and at intervals after they had discontinued its use showed that abnormal tryptophan metabolism may persist for three months or longer. Megestrol acetate, a progestagen used as an oral contraceptive, was found to have no significant effect upon tryptophan metabolism.The possible clinical significance of the effects of oral contraceptives upon tryptophan metabolism is discussed.

Aspects of tryptophan metabolism in health and disease: a review.

Some of the more recent developments in the study of tryptophan metabolism are reviewed with the intent of demonstrating that abnormalities associated with abnormal tryptophan metabolism may result from the influence of hormonal and nutritional factors upon the metabolic pathway. It has been shown that pregnancy and treatment with estrogens or estrogen-containing oral contraceptives (OCs) all produce elevated urinary excretion of tryptophan metabolites; administration of pyridoxine will normalize urinary levels. The effect of estrogens upon tryptophan oxygenase appears to be indirect mediated via the adrenals. The clinical significance of changes following OC use is unknown but evidence of an occult Vitamin-B6 deficiency is being sought. It is possible that OC/tryptophan-associated depression results when a patient lacks a compensatory biochemical mechanism that normally counters any reduction in the level of brain 5-hydroxytryptamine. In any event it is important to exclude all patients receiving estrogens from studies which attempt to demonstrate an association between abnormal tryptophan metabolism and a specific disease.

Studies on tryptophan metabolism in male subjects treated with hydrocortisone.

ABSTRACT The influence of hydrocortisone on urinary excretion of metabolites of the kynurenine pathway of tryptophan metabolism has been studied in male subjects. Hydrocortisone caused increased urinary excretion of tryptophan metabolites (i.e., kynurenine, acetylkynurenine, kynurenic acid, 3-hydroxykynurenine, and xanthurenic acid) after a loading dose of 2 g l-tryptophan, whereas urinary excretion of anthranilic acid metabolites was unchanged. The conversion of tryptophan to nicotinic acid metabolites was inhibited. Vitamin B6 supplementation normalized urinary excretion of tryptophan metabolites and caused an increase in urinary excretion of anthranilic acid metabolites. These results indicate that the capacity of the kynurenine pathway is exceeded by a loading dose of 2 g l-tryptophan when tryptophan pyrrolase, the first step of the kynurenine pathway, is induced by hydrocortisone. On the other hand, hydrocortisone seems to inhibit the extent to which tryptophan enters the NAD pathway.

The effect of tryptophan load and vitamin B 6 supplementation on urinary excretion of tryptophan metabolites in human male subjects.

1. Urinary excretion of tryptophan metabolites of the kynurenine pathway before and after a loading dose of 2 g of l-tryptophan (both before and during supplementation with vitamin B6) was studied in normal young male subjects and in elderly male subjects with prostatic diseases. 2. The increase in urinary excretion of tryptophan metabolites in the normal male subjects after a loading dose of 2 g of l-tryptophan was unchanged after vitamin B6 supplementation, indicating that this dose does not exceed the normal capacity of the kynurenine pathway. 3. It is therefore concluded that a loading dose of 2 g of l-tryptophan is preferable when studying the capacity of the kynurenine pathway. 4. In about three-quarters of the elderly male subjects with prostatic diseases, the capacity of the kynurenine pathway was normal. 5. In about one-quarter of the subjects with prostatic diseases after a loading dose of 2 g of l-tryptophan there was abnormally high urinary excretion of one or several tryptophan metabolites, which could be normalized by vitamin B6, indicating that the capacity of the kynurenine pathway had been exceeded in these subjects. 6. Urinary excretion of individual tryptophan metabolites after a loading dose of 2 g of l-tryptophan was constant in the same subject when studied under unchanged conditions, whether there was a normal or a decreased capacity of the kynurenine pathway. 7. It is concluded that a single determination of urinary excretion of tryptophan metabolites after a loading dose of 2 g of l-tryptophan is sufficient to determine the capacity of the kynurenine pathway.

The influence of nicotinamide on the urinary excretion of tryptophan metabolites in Hodgkin's disease.

Abstract The urinary excretion of tryptophan metabolites was studied in 10 patients with Hodgkin's disease. As previously found, kynurenine, 3-hydroxykynurenine and 3-hydroxyanthranilic acid were spontaneously excreted in abnormally high amounts, appearing to be a constant characteristic in patients with Hodgkin's disease. Tryptophan loading produced an abnormal excretion of 10 metabolites in all, and normal excretion was only partially restored by treatment with nicotinamide administration before a second tryptophan test in the same patients. The effect of nicotinamide on the excretion pattern appeared to differ qualitatively and quantitatively from that obtained using vitamin B6 administration. These data show the existence, in Hodgkin's disease, of a deficiency of nicotinamide-dependent enzymes acting on the tryptophan → nicotinic acid pathway, besides that correlated to vitamin B6.

Studies on tryptophan metabolism in male subjects treated with progestational agents.

The influence of a combination of estrogen and gestogen or of gestogens alone on tryptophan metabolism was studied in male subjects. Administration of both estrogen and gestogen caused increased urinary excretion of meta bolites of tryptophan and nicotinic acid after a loading dose of tryptophan, whereas gestogens alone caused decreased urinary excretion of nicotinic acid metabolites. Vitamin B6 supplementation was able to normalize urinary excretion of tryptophan metabolites, but had no effect on urinary excretion of nicotinic acid metabolites. These results indicate that there is a control by female sex hormones of tryptophan metabolism in man.

Pathology as Related to Tryptophan Metabolite Excretion, Occupational History, and Smoking Habits in Patients With Bladder Cancer<xref ref-type="fn" rid="FN1">1</xref>

There were no significant histologic differences between the bladder cancers in 39 patients with normal urinary excretion of tryptophan metabolites and those in 10 patients with abnormal metabolite excretion patterns. Neither were there statistically significant differences in histology between “occupational” and “spontaneous” tumors, nor between tumors in patients who had “ever smoked” cigarettes and those who had “never smoked” cigarettes. However, in both the “occupational” and the “ever-smoked” groups, apparently greater numbers of carcinomas were either wholly or partially composed of squamous elements, and further study of this point in larger series of cases seems indicated. For such studies, case material will be needed, not only from industries in which employees have had known exposures to materials later shown to be bladder carcinogens, but from nonindustrial sources after careful direct, personal interviews have divided cases into those with possible or definite occupational exposure and those with no history of exposure to the currently known occupational carcinogens.