High-fat simple carbohydrate (HFSC) diet impairs hypothalamic and corpus striatal serotonergic metabolic pathway in metabolic syndrome (MetS) induced C57BL/6J mice.

OBJECTIVES: To study the effect of specially formulated high-fat simple carbohydrate diet (HFSC) on the serotonin metabolic pathway in male C57BL/6J mice. METHODS: Previous studies from our laboratory have shown that specially formulated HFSC induces metabolic syndrome in C57BL/6J mice. In the present investigation, 5-hydroxytryptophan, serotonin and 5-hydroxyindoleacetic acid were analyzed in two brain regions (hypothalamus, corpus striatum), urine and plasma of HFSC-fed mice on a monthly basis up to 5 months using high-performance liquid chromatography fitted with electrochemical detector. The data were analyzed using Graph pad Prism v7.3 by two-way ANOVA and post hoc Tukey's test (to assess the effect of time on the serotonergic metabolic pathway). RESULTS: HFSC feed was observed to lower the hypothalamic serotonergic tone as compared to the age-matched control-fed C57BL/6J mice. Although the hypothalamic serotonergic tone was unaltered over time due to consumption of diet per se, hypothalamic 5-HTP levels were observed to be lower on consumption of HFSC feed over duration of 5 months as compared to 1st month of consumption of HFSC feed. The striatal 5-HTP levels were lowered in the HFSC-fed mice after 4 months of feeding as compared to the age-matched control-fed mice. The striatal 5-HTP levels were also lower in both control and HFSC-fed mice due to consumption of the respective diet over a duration of 5 months. Increased plasma 5-HTP levels were observed due to consumption of HFSC feed over duration of 5 months in the HFSC-fed group. However, higher breakdown of serotonin was observed in both the plasma and urine of HFSC-fed C57BL/6J mice as per the turnover studies. DISCUSSION: The central and peripheral serotonergic pathway is affected differentially by both the type of diet consumed and the duration for which the diet is consumed. The hypothalamic, striatal and plasma serotonergic pathway were altered both by the type of feed consumed and the duration of feeding. The urine serotonergic pathway was affected by mainly the duration for which a particular diet was consumed. These findings may have implications in the feeding behavior, cognitive decline and depression associated with metabolic syndrome patients.

Urine Metabonomics Reveals Early Biomarkers in Diabetic Cognitive Dysfunction.

Recently, increasing attention has been paid to diabetic encephalopathy, which is a frequent diabetic complication and affects nearly 30% of diabetics. Because cognitive dysfunction from diabetic encephalopathy might develop into irreversible dementia, early diagnosis and detection of this disease is of great significance for its prevention and treatment. This study is to investigate the early specific metabolites biomarkers in urine prior to the onset of diabetic cognitive dysfunction (DCD) by using metabolomics technology. An ultra-high performance liquid-chromatography-quadrupole time-of-flight-mass spectrometry (UPLC-Q/TOF-MS) platform was used to analyze the urine samples from diabetic mice that were associated with mild cognitive impairment (MCI) and nonassociated with MCI in the stage of diabetes (prior to the onset of DCD). We then screened and validated the early biomarkers using OPLS-DA model and support vector machine (SVM) method. Following multivariate statistical and integration analysis, we found that seven metabolites could be accepted as early biomarkers of DCD, and the SVM results showed that the prediction accuracy is as high as 91.66%. The identities of four biomarkers were determined by mass spectrometry. The identified biomarkers were largely involved in nicotinate and nicotinamide metabolism, glutathione metabolism, tryptophan metabolism, and sphingolipid metabolism. The present study first revealed reliable biomarkers for early diagnosis of DCD. It provides new insight and strategy for the early diagnosis and treatment of DCD.

Metabolomics Identifies Multiple Candidate Biomarkers to Diagnose and Stage Human African Trypanosomiasis.

Treatment for human African trypanosomiasis is dependent on the species of trypanosome causing the disease and the stage of the disease (stage 1 defined by parasites being present in blood and lymphatics whilst for stage 2, parasites are found beyond the blood-brain barrier in the cerebrospinal fluid (CSF)). Currently, staging relies upon detecting the very low number of parasites or elevated white blood cell numbers in CSF. Improved staging is desirable, as is the elimination of the need for lumbar puncture. Here we use metabolomics to probe samples of CSF, plasma and urine from 40 Angolan patients infected with Trypanosoma brucei gambiense, at different disease stages. Urine samples provided no robust markers indicative of infection or stage of infection due to inherent variability in urine concentrations. Biomarkers in CSF were able to distinguish patients at stage 1 or advanced stage 2 with absolute specificity. Eleven metabolites clearly distinguished the stage in most patients and two of these (neopterin and 5-hydroxytryptophan) showed 100% specificity and sensitivity between our stage 1 and advanced stage 2 samples. Neopterin is an inflammatory biomarker previously shown in CSF of stage 2 but not stage 1 patients. 5-hydroxytryptophan is an important metabolite in the serotonin synthetic pathway, the key pathway in determining somnolence, thus offering a possible link to the eponymous symptoms of "sleeping sickness". Plasma also yielded several biomarkers clearly indicative of the presence (87% sensitivity and 95% specificity) and stage of disease (92% sensitivity and 81% specificity). A logistic regression model including these metabolites showed clear separation of patients being either at stage 1 or advanced stage 2 or indeed diseased (both stages) versus control.

Quantitative analysis of multiple urinary biomarkers of carcinoid tumors through gold-nanoparticle-assisted laser desorption/ionization time-of-flight mass spectrometry.

A simple technique for quantitative analysis of four urinary biomarkers, tryptophan (TRP), 5-hydroxytryptophan (5-HTP), 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) of carcinoid tumors is developed using gold nanoparticles as the assisted matrix in surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS). The optimal SALDI conditions for the efficient ionization of those biomarkers are systematically explored by the adjustments of the concentrations of gold nanoparticles and internal standards. The mass spectra with strong signals and minimal background noise are obtained using 1-naphthaleneacetamide (NAD) as the internal standard. The calibration curves of the biomarker concentrations are determined using SALDI-TOF MS and the high linearity is obtained in all samples. For future clinical testing, multiplexed detection of those biomarkers in the urine samples of healthy males is performed. The successful quantitative detections of TRP, 5-HTP, 5-HT and 5-HIAA indicate that our technique provided great potentials to be developed a simple and rapid platform for the tumor biomarker detections.

Comprehensive feature analysis for sample classification with comprehensive two-dimensional LC.

Comprehensive two-dimensional LC (LC x LC) is a powerful tool for analysis of complex biological samples. With its multidimensional separation power and increased peak capacity, LC x LC generates information-rich, but complex, chromatograms, which require advanced data analysis to produce useful information. An important analytical challenge is to classify samples on the basis of chromatographic features, e.g., to extract and utilize biomarkers indicative of health conditions, such as disease or response to therapy. This study presents a new approach to extract comprehensive non-target chromatographic features from a set of LC x LC chromatograms for sample classification. Experimental results with urine samples indicate that the chromatographic features generated by this approach can be used to effectively classify samples. Based on the extracted features, a support vector machine successfully classified urine samples by individual, before/after procedure, and concentration with leave-one-out and replicate K-fold cross-validation. The new method for comprehensive chromatographic feature analysis of LC x LC separations provides a potentially powerful tool for classifying complex biological samples.

Characterization of pu-erh tea using chemical and metabolic profiling approaches.

In this study, the chemical constituents of pu-erh tea, black tea, and green tea, as well as those of pu-erh tea products of different ages, were analyzed and compared using a chemical profiling approach. Differences in tea processing resulted in differences in the chemical constituents and the color of tea infusions. Human biological responses to pu-erh tea ingestion were also studied by using ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS) in conjunction with multivariate statistical techniques. Metabolic alterations during and after pu-erh tea ingestion were characterized by increased urinary excretion of 5-hydroxytryptophan, inositol, and 4-methoxyphenylacetic acid, along with reduced excretion of 3-chlorotyrosine and creatinine. This study highlights the potential for metabonomic technology to assess nutritional interventions and is an important step toward a full understanding of pu-erh tea and its influence on human metabolism.

Elevated plasma chromogranin A is the first indication of recurrence in radically operated midgut carcinoid tumors.

BACKGROUND: Patients with malignant midgut carcinoids are occasionally diagnosed with limited tumor spread, and surgery with radical intention is performed. Despite curative intent, recurrences occur frequently, motivating long-term biochemical and radiological follow-up. This study aimed to compare the usefulness of various methods in detecting such recurrences. METHODS: This retrospective study included 56 patients with radically operated midgut carcinoids referred to our University Hospital for evaluation and follow-up between 1985 and 2004. Patients were monitored 1-3 times per year using plasma-chromogranin A (P-CgA), urinary 5-hydroxyindoleacetic acid (U-5HIAA) concentrations as well as radiological examinations, including ultrasonography, computerized tomography or magnetic resonance investigation. In a subset of cases, somatostatin receptor scintigraphy and/or positron emission tomography with 5-hydroxytryptophan was performed. Time from operation until established recurrence was recorded. RESULTS: Tumor recurrence was established in 33 of 56 patients after a median of 32 months (range 6-217). Elevated P-CgA was the first marker to become pathologically elevated in 28 of these 33 patients (85%). In 3 of these 28 patients, radiology was simultaneously positive for a recurrence. CONCLUSION: P-CgA was the first marker to indicate tumor recurrence in the majority of radically operated midgut carcinoid patients. To avoid unnecessary and costly examinations in asymptomatic patients, we suggest that follow-up should comprise measurements of P-CgA twice a year and annual ultrasonography until P-CgA is elevated or clinical symptoms occur, at which time all efforts should be made to identify recurrent tumor lesions in order to give the patient the best possible treatment which, if possible, should be surgical removal of the recurrence.

Determination of catecholamines and indoleamines in human urine based on intramolecular excimer-forming derivatization and fluorescence detection.

A liquid chromatographic (LC) determination of catecholamines and indoleamines is described. This is based on intramolecular excimer-forming fluorescence derivatization with 4-(1-pyrene)butanoyl chloride, followed by reversed-phase LC. The analytes, containing an amino moiety and phenolic hydroxyl moieties in a molecule, were converted to the corresponding polypyrene-labeled derivatives by one-step derivatization. They afforded intramolecular excimer fluorescence, which can clearly be discriminated from the normal fluorescence emitted from reagent blanks. The detection limits (S/N = 3) for catecholamines and indoleamines were femto-mole levels per 20-microL injection. Furthermore, this method was applied to a urine assay.

Determination of urinary 5-hydroxytryptophol glucuronide by liquid chromatography-mass spectrometry.

5-Hydroxytryptophol glucuronide (GTOL) is the major excretion form of 5-hydroxytryptophol (5-HTOL), a minor serotonin metabolite under normal conditions. Because the concentration of 5-HTOL is markedly increased following consumption of alcohol, measurement of 5-HTOL is used as a sensitive biomarker for detection of recent alcohol intake. This study describes the development and evaluation of a liquid chromatography-electrospray ionization mass spectrometry (LC-MS) procedure for direct quantification of GTOL in human urine. Deuterium labelled GTOL (GTOL-(2)H(4)) was used as internal standard. GTOL was isolated from urine by solid-phase extraction on a C(18) cartridge prior to injection onto a gradient eluted Hypurity C(18) reversed-phase HPLC column. The detection limit of the method was 2.0 nmol/L and the measuring range 6-8500 nmol/L. The intra- and inter-assay coefficients of variation were <3.5% (n=10) and <6.0% (n=9), respectively. The new LC-MS method was highly correlated with an established GC-MS method for urinary 5-HTOL (r(2)=0.99, n=70; mean 5-HTOL/GTOL ratio=1.10). This is the first direct assay for quantification of GTOL in urine. The method is suitable for routine application.

The effect of oral 5-HTP administration on 5-HTP and 5-HT immunoreactivity in monoaminergic brain regions of rats.

5-Hydroxytryptophan (5-HTP), which is the rate-limiting precursor in serotonin (5-hydroxytryptamine (5-HT)) biosynthesis, is used as an oral supplement to enhance serotonin levels in humans. To evaluate its effects on serotonin levels and localization, 5-hydroxytryptophan was administered to Sprague-Dawley rats either orally or via intraperitoneal injection. 5-Hydroxytryptophan-immunoreactivity was co-localized with serotonin-immunoreactivity in the serotonergic dorsal raphe nucleus of control animals and this was not changed in animals given 5-hydroxytryptophan. Oral 5-HTP administration increased the intensity of both 5-HTP and serotonin immunoreactivity in raphe neurons. However, 5-HTP treatment also caused ectopic 5-hydroxytryptophan-immunoreactivity and serotonin-immunoreactivity in normally dopaminergic neurons of the substantia nigra par compacta. Serotonin-immunoreactivity was confined to neurons that also displayed amino acid decarboxylase immunoreactivity, but in a small percentage of substantia nigra neurons, serotonin immunoreactivity was not co-localized with tyrosine hydroxylase-immunoreactivity. The intensity of the immunoreactivity to serotonin and 5-hydroxytryptophan in the substantia nigra was maximal within 2h of 5-hydroxytryptophan administration and returned to control levels by 24h. This time course mirrored changes in HPLC measurements of 5-hydroxytryptophan, serotonin, and the metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the urine. 5-Hydroxytryptophan administration did not cause ectopic appearance of either serotonin or 5-hydroxytryptophan in the noradrenergic locus coeruleus. These results suggest that a single oral dose of 5-HTP increases the 5-HTP and serotonin content of serotonergic neurons and causes the transient ectopic appearance of serotonin in some normally non-serotonergic neurons.

The effects of infrared laser and medical treatments on pain and serotonin degradation products in patients with myofascial pain syndrome. A controlled trial.

In this controlled study of 46 patients with myofascial pain syndrome, we investigated the effects of infrared (IR) laser application to trigger points and medical treatment on pain reduction and serotonin and its degradation products. Retaining double-blind trial principles, the patients were randomly assigned to two groups. The treatment group received IR laser treatment, whereas the control group received sham laser. However, both groups received medical treatment. In the treatment group, laser was applied once a day for 10 consecutive days at a dose of 1.44 J/cm2. The effect of the laser treatment on pain was evaluated by visual analog scale. Urinary excretion of 5-hydroxy indole acetic acid (5-HIAA) and serotonin + 5-hydroxy tryptophan (5-HT+5-HTP) was studied by column chromatography. At the end of the treatment, there was a statistically significant difference between the VAS values of the treatment and control groups. The 24-h urinary excretion of the 5-HIAA and 5-HT+5-HTP was significantly higher in the laser treatment group than in the placebo group. In conclusion, IR laser is an effective modality in the treatment of MPS which increases an important mediator of pain inhibition, serotonin.

5-hydroxytryptophol as a marker for recent alcohol intake.

AIMS: To review the mechanism behind the alcohol-induced shift in serotonin metabolism, and the use of urinary 5-hydroxytryptophol (5-HTOL) as a biochemical marker of acute alcohol consumption. BACKGROUND: The serotonin metabolite 5-HTOL is a normal, minor constituent of urine and is excreted mainly in conjugated form with glucuronic acid. The formation of 5-HTOL increases dramatically after alcohol intake, due to a metabolic interaction, and the elevated urinary excretion remains for some time (>5-15 hours depending on dose) after ethanol has been eliminated. This biochemical effect can be used for detection of recent alcohol intake. RESULTS: 5-HTOL is determined by the gas chromatography-mass spectrometry (GC-MS) or liquid chromatography and mass spectrometry (LC-MS) techniques. A new ELISA method for 5-HTOL glucuronide provides a promising clinical assay. The most robust way to use the marker is by measuring the ratio of 5-HTOL to 5-hydroxyindoleacetic acid, because this compensates for urine dilution and dietary intake of serotonin. 5-HTOL is a very sensitive and specific indicator of recent alcohol consumption and, as such, a valuable complement to self-report. In clinical use, 5-HTOL is effective for monitoring lapses into drinking during out-patient treatment and for objective evaluation of treatment efforts. Other applications include detection of high-risk patients in elective surgery, monitoring of disulfiram treatment and a method to rule out artefactual ethanol formation in forensic toxicology. 5-HTOL can also be used as a sensitive reference method for validation of self-report data in clinical alcohol research. CONCLUSIONS: An elevated urinary 5-HTOL level can serve as a sensitive and reliable marker for recent alcohol intake with a number of clinical and forensic applications.

Comparison of self-reported alcohol intake with the urinary excretion of 5-hydroxytryptophol:5-hydroxyindole-3-acetic acid, a biomarker of recent alcohol intake.

Under-reporting of alcohol intake has been frequently reported. However, due to the lack of an objective reference method, e.g. a biomarker, information about the extent of under-reporting of alcohol intake obtained with dietary assessment instruments is not available. The objective of this study was to compare reported alcohol intake data derived from a 24 h recall with a biomarker of recent alcohol intake, the urinary excretion of 5-hydroxytryptophol (5-HTOL):5-hydroxyindole-3-acetic acid (5-HIAA). Embedded into the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam Study, Germany, a validation study that collected 24 h recall data and 24 h urine samples was conducted. Cohort study participants (n 107) volunteered to participate in this validation study. Among them were five subjects who reported no consumption of alcoholic beverages but had a 5-HTOL:5-HIAA ratio that indicated recent alcohol intake when the clinical cut-off point was taken as a judging criterion. After exclusion of these under-reporters, the Pearson's correlation coefficient between reported alcohol intake and the 5-HTOL:5-HIAA ratio was 0.92 (P<0.0001). Except for low alcohol intake of <0.1 g/kg body mass, a significant increase in 5-HTOL:5-HIAA excretion was observed with increasing amounts of alcohol intake. In conclusion, the 5-HTOL:5-HIAA excretion ratio appears to be a valuable quantitative biomarker of recent alcohol consumption. Denial of alcohol intake can be detected, but for the quantification of under-reporting of alcohol intake 24 h reference data are not yet available. With these data at hand, however, 5-HTOL:5-HIAA could become a biomarker for validation purposes in nutritional epidemiology.

Effects of long-term abstinence on psychological functioning: a prospective longitudinal analysis comparing alcohol-dependent patients and healthy volunteers.

Using a prospective longitudinal design, differences between abstinent alcohol-dependent patients (n = 15) and abstinent healthy volunteers (n = 11) were determined with respect to their psychological functioning and alcohol consumption patterns following abstinence. Results showed no differences in alcohol consumption. In 20% of the patients and 9% of the controls more than 10% of protocols indicated alcohol intake, and in 27% of the patients and 27% of the controls less than 10% of protocols indicated alcohol intake. Total abstinence was reported by 53% of the patients and by 64% of the controls. For patients, validation of self-reported alcohol consumption was carried out via biological markers. Patients and controls differed in terms of increased sleep, euphoria, concentration, initiative, anxiety, negative and positive craving, pessimistic thoughts, autonomic disturbances, and humour. A gradual normalization back to baseline levels was observed for some symptoms. These results suggest that affective/mood states may be unstable for alcoholics, and further, that these symptoms may be related to the protracted withdrawal syndrome or may represent residual symptomatology.

gamma-L-glutamyl-5-hydroxy-L-tryptophan, but not gamma-L-glutamyl-L-tryptophan, causes sodium retention in normal man.

1. This randomized, placebo-controlled, cross-over study compared the relative effectiveness of gamma-L-glutamyl-5-hydroxy-L-tryptophan (glu-5-HTP) and gamma-L-glutamyl-L-tryptophan (glu-TRP) in terms of their ability to act as substrates for renal 5-hydroxytryptamine (5-HT) synthesis and their actions on urinary sodium excretion. 2. Urinary excretion of 5-HT and sodium were determined before, during and after 1 h intravenous infusion of an equimolar amount (45 nmol kg-1 min-1) of glu-5-HTP or glu-TRP or placebo in nine healthy male subjects. 3. Cumulative urinary 5-HT excretion over the 4 h after the start of glu-5-HTP infusion was 350-fold greater than that after placebo, and this was associated with a reduction in the urinary excretion of sodium. 4. In contrast, the urinary excretion values of 5-HT and sodium after administration of glu-TRP were not significantly different from those observed on the placebo day. 5. The marked increase in urinary 5-HT excretion and the retention of sodium after administration of glu-5-HTP have been demonstrated in previous studies and result from increased intrarenal generation of 5-HT. The absence of a rise in urinary excretion of 5-HT after glu-TRP infusion suggests that there was no significant conversion of this glutamyl compound to 5-HT within the kidney. As a result, there was no effect on urinary sodium excretion.

Renal metabolism and effects of the glutamyl derivatives of L-dopa and 5-hydroxytryptophan in man.

1. Equimolar amounts of gamma-L-glutamyl-L-3,4-dihydroxyphenylalanine (gludopa) and gamma-L-glutamyl-5-hydroxy-L-tryptophan were infused separately and together in eight healthy, salt-replete male subjects in a placebo-controlled, cross-over study to investigate whether the administration of one amine precursor affects the renal metabolism of the other and to determine whether dopamine or 5-hydroxytryptamine would be generated preferentially. The overall effect on sodium excretion was also measured when both precursors were administered simultaneously. 2. Administration of gludopa was associated with marked increases in the urinary excretion of L-dopa, dopamine and 3,4-dihydroxyphenylacetic acid, together with a rise in the urinary excretion of sodium. gamma-L-Glutamyl-5-hydroxy-L-tryptophan, on the other hand, produced marked increases in the urinary excretion of 5-hydroxy-L-tryptophan, 5-hydroxy-tryptamine and 5-hydroxyindoleacetic acid, and this was accompanied by a slight, but non-significant, reduction in sodium excretion. About 27% of the infused dose of gludopa (on a molar basis) was recovered in the urine as dopamine whereas 15% of the given dose of gamma-L-glutamyl-5-hydroxy-L-tryptophan was excreted as 5-hydroxytryptamine. 3. The urinary excretion values of L-dopa, dopamine and 3,4-dihydroxyphenylacetic acid after the simultaneous infusion of gludopa and gamma-L-glutamyl-5-hydroxy-L-tryptophan were not significantly different from those observed after infusion of gludopa only. Similarly, the urinary excretion values of 5-hydroxy-L-tryptophan, 5-hydroxytryptamine and 5-hydroxy-indoleacetic acid during the co-infusion were similar to those measured after administration of gamma-L-glutamyl-5-hydroxy-L-tryptophan only. The net effect of the concomitant infusion of both glutamyl derivatives was an increase in urinary sodium excretion. 4. Our study in salt-replete individuals suggests that dopamine rather than 5-hydroxytryptamine was preferentially produced when equimolar amounts of their precursors were provided and that the natriuretic effect of dopamine, generated intrarenally from gludopa, was greater than the sodium retaining action of 5-hydroxytryptamine derived from gamma-L-glutamyl-5-hydroxy-L-tryptophan. Comparison of the urinary metabolite data after the separate and concomitant infusion of the two glutamyl compounds provided no evidence of competitive inhibition of synthesis of either amine.

[Gastric carcinoid. A clinical case and review of the literature]. / Carcinoide gastrico. Caso clinico e revisione della letteratura.

INTRODUCTION: Endoscopic examination of the gastrointestinal tract is very useful, because it allows a rapid diagnosis and, in some cases, a therapeutical effect. CLINICAL CASE: The authors have seen a woman, 72 years old, with epigastric pain, dryness of the mouth, diarrhoea and meteorism. She had an old simple gastritis (of two years standing) and her therapy, since the time of the diagnosis, is omeprazole (20 mg/die). The patient was submitted to gastroscopic examination that revealed two spot lesions and a polypous lesion on which was made a biopsy. The patient was submitted also to the following examination: 1) urinary dosage of 5 HIAA; 2) urinary dosage of 5 OHT; 3) Computed tomography of the abdomen; 4) Heart echography; 5) Endoscopy of the colon; 6) Endoscopy of the bronchus. DISCUSSION: Carcinoid tumors are usually small and rare lesions and they are in the following sites: A) between mouth and the second part of duodenum; B) between the second part of the duodenum and the transverse segment of the colon; C) between the latter and the anus. CLINICAL PICTURE: Patients are usually 50-60 years old, with other neoplasm. The picture is marked by flushing, diarrhoea, abdominal cramp and disease of the right heart valve. DIAGNOSIS: Diagnosis is based on urinary dosage of 5-HIAA (n.v. > 10 mg/24 h.) that is higher than the normal value. Computed tomography and echography are useful. THERAPY: The small neoplasm are treated by local surgical resection, while the biggest tumors have been treated by pharmacological therapy with useless results.

Blood and urine 5-hydroxytryptophan and 5-hydroxytryptamine levels after administration of two 5-hydroxytryptamine precursors in normal man.

Six healthy male subjects received equimolar amounts of two 5-hydroxytryptamine (5-HT) precursors, 5-hydroxy-L-tryptophan (5-HTP) and gamma-L-glutamyl-5-hydroxy-L-tryptophan (glu-5-HTP), on two occasions in a randomised cross-over study. There were marked increases in urinary 5-HTP and 5-HT excretion after infusion of both compounds. Mean urinary excretion rate of 5-HT, which was < 0.7 nmol min-1 before dosing, rose to a peak value of 412 +/- 92 nmol min-1 at the end of 5-HTP infusion and 303 +/- 29 nmol min-1 after administration of glu-5-HTP. This occurred without significant changes in blood 5-HT levels measured in platelet-rich plasma. These findings provide further evidence that the increase in urine 5-HT after administration of both 5-HT precursors is largely due to 5-HT synthesised within the kidney.

A comparison of the renal and neuroendocrine effects of two 5-hydroxytryptamine renal prodrugs in normal man.

1. The effects of 1 h intravenous infusions of equimolar amounts (45 nmol min-1 kg-1) of two putative 5-hydroxytryptamine renal prodrugs, 5-hydroxy-L-tryptophan and gamma-L-glutamyl-5-hydroxy-L-tryptophan, were investigated in a randomized, placebo-controlled, cross-over study in nine healthy male subjects. 2. Cumulative urinary 5-hydroxytryptamine excretion over the 3 h observation period rose by about 370-fold after 5-hydroxy-L-tryptophan and 390-fold after gamma-L-glutamyl-5-hydroxy-L-tryptophan when compared with placebo infusion. Urinary 5-hydroxy-L-tryptophan excretion was three times higher after administration of gamma-L-glutamyl-5-hydroxy-L-tryptophan than after 5-hydroxy-L-tryptophan infusion. Urinary 5-hydroxyindole-3-acetic acid excretion after 5-hydroxy-L-tryptophan infusion was significantly greater than that after gamma-L-glutamyl-5-hydroxy-L-tryptophan administration. Urinary dopamine excretion was not affected by either compound when compared with placebo. 3. 5-Hydroxy-L-tryptophan significantly reduced urine flow rate and urinary sodium excretion. gamma-L-Glutamyl-5-hydroxy-L-tryptophan was antinatriuretic but did not affect urine output. These changes occurred without significant alterations in effective renal plasma flow and glomerular filtration rate. 4. Both 5-hydroxy-L-tryptophan and gamma-L-glutamyl-5-hydroxy-L-tryptophan significantly increased plasma aldosterone concentration without a concomitant rise in plasma renin activity.(ABSTRACT TRUNCATED AT 250 WORDS)

High performance liquid chromatographic profiling of tryptophan and related indoles in body fluids and tissues of carcinoid patients.

A high performance liquid chromatographic method with quaternary gradient elution and fluorometric detection was developed for profiling of tryptophan (TRP), 5-hydroxytryptophan, serotonin (5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA) in urine, platelet-rich plasma and (tumour) tissue of patients with carcinoid tumours. Prior to injection, urine samples were diluted and filtered. Platelet-rich plasma and tissue homogenates were prepurified by C18 solid phase extraction. Detection limits were approx. 2 pmol. Results of urinary 5-HT and 5-HIAA compared favourably with those of single component analyses. No consistent diurnal variations were found for TRP, 5-HT and 5-HIAA in 12-h urine samples from 15 healthy adults. Abstinence of 5-HT-rich foods reduced urinary levels of 5-HT and 5-HIAA. C18 extraction of indoles from protein-containing matrices was studied in platelet-rich plasma. Although time-consuming and complicated for daily routine use, the present approach offers particular advantages over single component analyses in the study of TRP metabolism in patients with carcinoid tumours.