Total Tryptophan Research Articles

Influence of Zinc, Boron and Molybdenum Application on Biochemical Composition of Chickpea Grain Grown under Rainfed Conditions of Madhya Pradesh

The effect of application of micronutrients viz. zinc, boron and molybdenum on the biochemical and nutritional quality of chickpea variety Avarodhi was studied during 2012–13 and 2013–14. The application of zinc @ 5.0 kg ha−1 increased grain protein to 21.21% and protein yield to 470.69 kg ha−1. Tryptophan of grain increased significantly on application of zinc, whereas methionine was not affected on zinc application either at 2.5 or 5.0 kg ha−1. Similarly, the application of boron @ 2.0 kg ha−1 gave the highest values of protein (20.65%), protein yield (450.35 kg ha−1), tryptophan (0.75 g/100 g protein) and ash content (2.99%), whereas methionine and lipid content were not affected. Application of molybdenum @ 400 g ha−1 increased the protein content of grain as well as total protein yield and tryptophan contents significantly. The carbohydrate decreased significantly with increasing levels of zinc, boron and molybdenum. Zinc application @ 5.0 kg ha−1 increased potassium, sulphur and zinc contents of grain significantly. Boron when applied @ 2.0 kg ha−1 and molybdenum @ 400 g ha−1 increased phosphorus, potassium, sulphur, boron and molybdenum contents of grain significantly.

Su2085 The Impact of Fear of GI Symptoms on Quality of Life Impairment Due to Irritable Bowel Syndrome

G A A b st ra ct s (Kennedy et al, 2013), which may be mediated by changes in downstream neuroactive metabolites of the kynurenine pathway. Therefore, in this study we investigated if modulating tryptophan availability using acute tryptophan depletion (ATD) altered peripheral levels of kynurenine and tryptophan in patients with IBS, and if modulating these parameters impacted on measures of cognition, mood, arousal, and self-reported GI symptoms. Design: Doubleblind, placebo-controlled, crossover design. Methods: Female patients with IBS who met Rome III criteria (N = 9; mean age = 22.8 +/1.2) and age and IQ matched female healthy controls (HC; N = 14; mean age = 21.5 +/0.5) each attended two study visits, receiving the tryptophan depleting (ATD) or control (TRP+) amino acid drink on each visit. Plasma samples were collected pre and post drink, and participants completed a range of tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB), including the paired associates learning (PAL) test, and self report measures of GI symptoms, mood and arousal. Results: As expected, ATD reduced total plasma tryptophan, by 74.02% in healthy controls and by 85.86% in IBS patients, p < .001. In addition, ATD reduced total plasma kynurenine, by 63.12% in healthy controls and by 69.63% in IBS patients, p < .001. Following TRP+, kynurenine concentrations were significantly elevated in both IBS patients and healthy control participants, p < .001. Moreover, patients with IBS exhibited impaired visuospatial memory performance following TRP+, PAL mean errors: HC = 2.4 +/0.9, IBS = 7.8 +/1.9, p < 0.05. However, ATD eliminated this deficit. ATD had no effect on GI symptoms in patients with IBS. Conclusions: Although the peripheral changes in kynurenine following ATD are similar in patients with IBS and healthy control participants, it appears patients with IBS process tryptophan or kynurenine differentially in the central nervous system. Our results have significant implications for our understanding of the underlying pathophysiology of IBS, and suggest that targeting the kynurenine pathwaymay be a novel strategy to normalise central dysfunction in IBS. References Fitzgerald, P., et al. (2008). Neurogastroenterology & Motility, 20, 1291-1297. Kennedy, P. J., et al. (2013). Psychological Medicine, doi:10.1017/ S0033291713002171

Enteric and serological distribution of serotonin and its precursor tryptophan in perinatal low and normal weight piglets

Perinatal mortality is high among small-for-gestational age (SGA) piglets and continues to be an economic burden and threat to animal welfare. As the physiological role of serotonin (5-hydroxytryptamine, 5-HT) in perinatal development and gastrointestinal function in the pig remains unknown, the aim of this study was to assess the enteric distribution of 5-HT cells and to determine 5-HT together with its precursor tryptophan in the serum of perinatal normal and SGA piglets. For this purpose, proximal and distal parts of the small intestine (SI) were processed for immunohistochemical analysis to assess the presence of 5-HT endocrine cells. Serum 5-HT was measured with ELISA, whereas its precursor, that is, the free fraction of tryptophan (FFT) together with albumin-bound tryptophan and total tryptophan, were analysed with HPLC in postnatal piglets. In addition, the morphological growth patterns of the different intestinal tissue layers of both normal and SGA piglets were stereologically analysed. The stereological volume density of 5-HT enteroendocrine cells showed a significant interaction effect between age and region. Indeed, the amount of 5-HT cells in both the proximal and distal part of the SI tended to decrease according to age, with the lowest values detected at day 3 postpartum. No differences could be observed related to BW. Interestingly, the serum concentration of 5-HT was higher in normal piglets compared with SGA piglets. Moreover, the ratio of FFT to total tryptophan was significantly affected by age and BW. Normal piglets had, on average, a lower FFT/total tryptophan ratio compared with SGA piglets. An approximate linear decrease was observed with increasing age. Finally, the immaturity of the intestinal system of the SGA piglets was not reflected in altered volume densities of the different intestinal layers. To conclude, although no BW effect could be detected in the distribution of enteric 5-HT cells, serum 5-HT and the ratio of FFT to total tryptophan ratio showed significant differences between normal piglets and their SGA littermates.

The tryptophan utilization concept in pregnancy.

The decrease in maternal plasma total (free + albumin-bound) tryptophan (Trp) during the third pregnancy trimester is attributed to induction of indoleamine 2,3-dioxygenase (IDO). When measured, free [Trp] is increased because of albumin depletion and non-esterified fatty acid elevation. The Trp depletion concept in pregnancy is therefore not supported because of incorrect interpretation of changes in Trp disposition and also for not addressing mouse strain differences in Trp-related responses and potential inhibition of Trp transport by the IDO inhibitor 1-methyl tryptophan. Application of the Trp utilization concept in pregnancy offers several physiological advantages favoring fetal development and successful outcome, namely provision of Trp for fetal protein synthesis and growth, serotonin for signaling pathways, kynurenic acid for neuroprotection, quinolinic acid for NAD+ synthesis, and other kynurenines for suppression of T cell responses. An excessive increase in Trp availability could compromise pregnancy by undermining T cell suppression, e.g., in pre-eclampsia.

Exercise Increases Tryptophan Availability to the Brain in Older Men Age 57–70 Years

Many aspects of serotonergic activity, both central and peripheral in origin, undergo significant changes with human aging. These alterations might predispose elderly people to develop mood disorders. Because previous work showed that increasing the peripheral availability of tryptophan (TRP) to the brain holds antidepressant properties, this study evaluated whether TRP availability to the brain is increased during prolonged exercise in older men. Nineteen males age 64 ± 3 yr completed a treadmill exercise bout at an HR eliciting ∼68% V˙O(2peak) for 60 min. Fasting blood was collected at rest, after 30 and 60 min of exercise, and at 90 min (after exercise). Branched-chain amino acids (BCAA), total and free TRP, prolactin, ammonia, nonesterified fatty acids, glucose, and lactate were measured. Changes in free TRP/BCAA ratio and prolactin were used as peripheral proxies of central serotonin synthesis rate and activity. The free TRP/BCAA ratio observed at baseline was increased by 102% after 1 h of exercise (P < 0.0001) and remained elevated after exercise (78% above baseline, P < 0.001). The free TRP portion in serum increased from 2.8 ± 0.7 to 5.7 ± 1.8 μmol·L⁻¹ after 1 h of exercise (P < 0.001) and was strongly correlated with plasma nonesterified fatty acid contents (r₁₇ = 0.887, P < 0.0001, all time points). Serum prolactin was significantly elevated after 1 h of exercise (8.6 ± 2.4 μg·L⁻¹, P < 0.001) and was positively correlated with free TRP/BCAA ratio (r₁₆ = 0.48, P < 0.05, all time points). These results concur with previous observations in younger men and unveil that significant elevations in TRP availability to the brain are encountered during sustained exercise in older men. These results provide support to the hypothesis that increases in serotonin synthesis and activity might be involved in the antidepressant effect of exercise in the elderly.

Total and free-plasma tryptophan concentrations in rheumatoid disease.

Abstract It has been proposed (McArthur, Dawkins &amp; others, 1971) that human connective tissue diseases may arise from modifications in the binding characteristics of the plasma proteins. McArthur, Smith &amp; Freeman (1972) presented evidence that human serum contains a substance that possesses anti-inflammatory activity and is bound to circulating proteins. Furthermore, it has been suggested that, in patients with active rheumatoid arthritis, the anti-inflammatory substance is bound to an abnormal extent to the plasma proteins and that the clinically useful antirheumatic drugs act by re-establishing the bound: free ratio to that in the normal subject (Smith &amp; Dawkins, 1971). There is evidence that the behaviour of L-tryptophan mimics that of the hypothetical substance which protects susceptible tissues against chronic inflammatory insults. All the clinically useful antirheumatic agents were found to displace L-tryptophan from human plasma in vitro (McArthur, Dawkins &amp; Smith, 1971) but not so other drugs which bind to plasma proteins to an equivalent extent but have no demonstrable antirheumatic effects (Smith, Dawkins &amp; McArthur, 1971). In patients with rheumatoid arthritis receiving drug therapy the percentage of L-tryptophan bound to plasma proteins is significantly reduced but increases when drug administration is stopped (McArthur, Dawkins &amp; others, 1971).

Detection of coronary atherosclerotic plaques with superficial proteoglycans and foam cells using real-time intrinsic fluorescence spectroscopy

ObjectivesThe protein components of low-density lipoprotein (LDL), oxidized LDL and proteoglycans such as versican contain tryptophan, an amino acid with characteristic fluorescence features at 308nm excitation wavelength. We hypothesize that intrinsic fluorescence spectroscopy at 308nm excitation wavelength IFS308, a method suitable for clinical use, can identify coronary artery lesions with superficial foam cells (SFCs) and/or proteoglycans. MethodsWe subjected 119 human coronary artery specimens to in vitro fluorescence and reflectance spectroscopy. We used 5 basis spectra to model IFS308, and extracted their contributions to each individual IFS308 spectrum. A diagnostic algorithm using the contributions of Total Tryptophan and fibrous cap to IFS308 was built to identify specimens with SFCs and/or proteoglycans in their top 50μm. ResultsWe detected SFCs and/or proteoglycans, such as versican or the glycosaminoglycan hyaluronan, in 24 fibrous cap atheromas or pathologic intimal thickening (PIT) lesions. An algorithm using the contributions of Total Tryptophan and fibrous cap to IFS308 was able to identify these segments with 92% sensitivity and 80% specificity. ConclusionWe were able to establish a set of characteristic LDL, oxidized LDL, versican and hyaluronan fluorescence spectra, ready to be used for real-time diagnosis. The IFS308 technique detects SFCs and/or proteoglycans in fibrous cap atheromas and PIT lesions. SFCs and proteoglycans are histological markers of vulnerable plaques, and this study is a step further in developing an invasive clinical tool to detect the vulnerable atherosclerotic plaque.

Increased serum free tryptophan in patients with diarrhea-predominant irritable bowel syndrome

Irregularities of serotonin function in irritable bowel syndrome (IBS) may be due to changes in the metabolism of the serotonin precursor l-tryptophan. Dietary alteration of tryptophan intake may impact upon the mood and bowel symptoms of IBS. We hypothesized that diarrhea-predominant irritable bowel syndrome (d-IBS) patients would exhibit an increase in plasma tryptophan due to alterations in tryptophan metabolism. We also hypothesized that a diet low in tryptophan would reverse this change and reduce symptoms. Thirteen patients with d-IBS had fasting serum free and total tryptophan, large neutral amino acids, and 6 kynurenine metabolites measured before and after 2 weeks of a strict dairy-free diet. Baseline tryptophan parameters were compared with an age- and sex-matched control group. Changes in the specific tryptophan parameters before and after dairy-free diet were correlated with symptoms of IBS and mood. Compared with the control group, d-IBS patients at baseline exhibited significantly higher free serum tryptophan (10.5 ± 4.35 vs 4.75 ± 2.43 μmol/L [means ± standard deviation], P = .006) and significantly lower tryptophan dioxygenase and total tryptophan oxidation as measured by the kynurenine to free tryptophan and total kynurenines to free tryptophan ratios (23.37 ± 10.12 vs 55.33 ± 16.02, P < .001 and 49.34 ± 17.84 vs 258.46 ± 98.67, P < .001, respectively). Dairy-free diet did not modulate metabolites of the kynurenine pathway or symptoms. Tryptophan metabolism along the kynurenine pathway is inhibited in d-IBS, and a dairy-free diet does not alter this. Our findings are consistent with possible enhanced serotonin activity in d-IBS.

Reduction of serum serotonin precursors after veralipride treatment for postmenopausal hot flushes

Objective The pathogenesis of hot flushes involves several brain neurotransmitter systems, and changes in serotonin turnover have been hypothesized. Veralipride is an anti-dopaminergic agent that relieves hot flushes and putatively also modulates serotonergic neurons. To further elucidate this relationship, in the present study we evaluated whether administration of veralipride for relief of hot flushes is able to affect serum levels of the serotonin precursor tryptophan in postmenopausal women.Methods Twenty-four postmenopausal women were randomly assigned to receive veralipride (100 mg/day) or similar placebo tablets for 3 months (n = 12 per group). Free tryptophan and total tryptophan (free + protein-bound) levels were assayed before and monthly by high pressure liquid chromatography. Data were analyzed with repeated measures ANOVA and Student–Newman–Keuls post hoc test.Results Relief of hot-flushes was achieved with complete suppression of symptoms after veralipride, but not placebo, treatment. In the veralipride group, total tryptophan levels significantly (p < 0.05) decreased from baseline (11.2 ± 0.4 μg/ml) to 3 months (8.0 ± 0.3 μg/ml), as well as free tryptophan concentrations (baseline 2.1 ± 0.1 μg/ml; after 3 months 1.3 ± 0.1 μg/ml; p < 0.05). No changes were recorded in the placebo group.Conclusion Women treated with veralipride for relief of menopausal symptoms show a decrease in serum levels of serotonin precursors, suggesting that the brain serotonergic system may be involved in the pathogenesis of postmenopausal vasomotor symptoms.

Brain serotonergic and dopaminergic modulators, perceptual responses and endurance exercise performance following caffeine co-ingested with a high fat meal in trained humans

BackgroundThe present study examined putative modulators and indices of brain serotonergic and dopaminergic function, perceptual responses, and endurance exercise performance following caffeine co-ingested with a high fat meal.MethodsTrained humans (n = 10) performed three constant-load cycling tests at 73% of maximal oxygen uptake (VO2max) until exhaustion at 10°C remove space throughout. Prior to the first test, subjects consumed a 90% carbohydrate meal (Control trial) and for the remaining two tests, a 90% fat meal with (FC trial) and without (F trial) caffeine.ResultsTime to exhaustion was not different between the F and FC trials (P > 0.05); [Control trial: 116(88-145) min; F trial: 122(96-144) min; FC trial: 127(107-176) min]. However, leg muscular discomfort during exercise was significantly lower on the FC relative to F trial (P < 0.01). There were no significant differences between F and FC trials in key modulators and indices of brain serotonergic (5-HT) and dopaminergic (DA) function [(i.e. plasma free and total tryptophan (Trp), tyrosine (Tyr), large neutral amino acids (LNAA), Trp:LNAA ratio, free-Trp:Tyr ratio, total Trp:Tyr ratio, and plasma prolactin] (P > 0.05) with the exception of plasma free-Trp:LNAA ratio which was higher at 90 min and at exhaustion during the FC trial (P < 0.05).ConclusionsNeither brain 5-HT nor DA systems would appear to be implicated in the fatigue process when exercise is performed without significant thermoregulatory stress, thus indicating fatigue development during exercise in relatively cold temperatures to occur predominantly due to glycogen depletion.

Changes on the levels of serotonin precursors – tryptophan and 5-hydroxytryptophan – during roasting of Arabica and Robusta coffee

Abstract The levels of free and total tryptophan and of 5-hydroxytryptophan (5-HTP) were investigated in green and roasted grains and beverages of Coffea arabica L. (Arabica) and Coffea canephora Pierre var. robusta (Robusta). Grains were light, medium and dark roasted. Free and protein tryptophan were extracted before and after hydrolysis. The levels of tryptophan and 5-HTP were quantified simultaneously by ion-pair HPLC and fluorimetric detection after derivatisation with o-phthalaldehyde. Robusta green coffee had higher total and protein tryptophan, whereas Arabica had higher free tryptophan levels. 5-HTP was not detected in the samples before and after roasting. Free tryptophan was completely degraded during roasting. Roasting significantly affected protein tryptophan. The rate of loss was smaller in Arabica compared to Robusta at every roasting degree. A beverage prepared the Brazilian way with a medium-roasted coffee provided 1.4–2.5 mg tryptophan/50 ml cup.

Determination of tryptophan in bee pollen and royal jelly by high‐performance liquid chromatography with fluorescence detection

A method for tryptophan analysis in bee pollen and royal jelly was developed using HPLC with fluorescence detection. To determine the free tryptophan in bee pollen and royal jelly, ultrasonic extraction was performed using water (pH 6.3)-acetonitrile (10:1, v/v) as extraction solvent. While determining the total tryptophan in these bee products, the method involves alkaline hydrolysis of the proteins with 4 mol/L sodium hydroxide at 110 degrees C for 20 h under anaerobic conditions. The operating conditions for the HPLC analysis were: Symmetry C(18) column (4.6 x 250 mm, 5 microm), 0.1% trifluoroacetic acid-methanol (75:25, v/v) as the mobile phase at a flow rate of 1.0 mL/min at 30 degrees C. The fluorescence detector was operated at an excitation wavelength of 280 nm and an emission wavelength of 340 nm. A linear response (r(2 )> 0.9998) was obtained in the range 0.0625-5.0 microg/mL. The method was successfully applied to the determination of the free and total tryptophan contents in bee pollens, which were 0.069 +/- 0.003 and 2.693 +/- 0.476 mg/g, respectively, while only the total tryptophan was detected in royal jelly, with a content of 1.743 +/- 0.066 mg/g.

Repeated Administration of Fresh Garlic Increases Memory Retention in Rats

Garlic (Allium sativum) is regarded as both a food and a medicinal herb. Increasing attention has focused on the biological functions and health benefits of garlic as a potentially major dietary component. Chronic garlic administration has been shown to enhance memory function. Evidence also shows that garlic administration in rats affects brain serotonin (5-hydroxytryptamine [5-HT]) levels. 5-HT, a neurotransmitter involved in a number of physiological functions, is also known to enhance cognitive performance. The present study was designed to investigate the probable neurochemical mechanism responsible for the enhancement of memory following garlic administration. Sixteen adult locally bred male albino Wistar rats were divided into control (n = 8) and test (n = 8) groups. The test group was orally administered 250 mg/kg fresh garlic homogenate (FGH), while control animals received an equal amount of water daily for 21 days. Estimation of plasma free and total tryptophan (TRP) and whole brain TRP, 5-HT, and 5-hydroxyindole acetic acid (5-HIAA) was determined by high-performance liquid chromatography with electrochemical detection. For assessment of memory, a step-through passive avoidance paradigm (electric shock avoidance) was used. The results showed that the levels of plasma free TRP significantly increased (P < .01) and plasma total TRP significantly decreased (P < .01) in garlic-treated rats. Brain TRP, 5-HT, and 5-HIAA levels were also significantly increased following garlic administration. A significant improvement in memory function was exhibited by garlic-treated rats in the passive avoidance test. Increased brain 5-HT levels were associated with improved cognitive performance. The present results, therefore, demonstrate that the memory-enhancing effect of garlic may be associated with increased brain 5-HT metabolism in rats. The results further support the use of garlic as a food supplement for the enhancement of memory.

Nonproteic Contents Interfere with the Analysis of Added Tryptophan in Feeds - Test of a Correction Model

The nonproteic, free tryptophan contents in 23 important feed ingredients were analysed. Wheat, its bran and middlings, soybean meal, sunflower meal and other vegetable feed ingredients contain significant fractions of free trypto- phan, up to 38% of total tryptophan. These natural contents considerably interfere with the accurate determination of sup- plemented L-tryptophan in mixed feeds. Two correction methods were successfully tested in four feeds, which were each supplemented at two levels. They allow a distinct improvement in the analysis of tryptophan addition.

Tryptophan hydroxylase gene ( TPH1) and peripheral tryptophan levels in depression

Background Genetic variants have been discovered in two genes encoding for tryptophan hydroxylase (TPH)— TPH1 and TPH2. Low tryptophan (TRP) levels are associated with depression and may arise because of stress. Evidence suggests that hypothalamic and peripheral 5HT systems have a significant role in appetite regulation, possibly a homeostatic mechanism in regulating peripheral TRP levels. Methods We examined the association between a polymorphism in intron 7 of TPH1, 218A > C and plasma total TRP levels in 118 patients with major depression. Results There was an interaction between 218A > C and gender in determining plasma TRP whereby presence of the 218C allele, in women, was associated with markedly reduced plasma TRP. Limitations The study investigated only the TRP1 gene and did not use a haplotype analysis. The results only apply to a population of subjects suffering from major depression. Conclusions TPH1 may be associated with the regulation of peripheral tryptophan levels and therefore availability of tryptophan to the brain. This may have relevance to a range of neuropsychiatric conditions.

High-performance liquid chromatography with fluorescence detection for quantitation of tryptophan and tyrosine in a shrimp waste protein concentrate

A new, simple, and reproducible isocratic high-performance liquid chromatography (HPLC) method has been developed for the determination of free and total tyrosine and tryptophan in a protein concentrate. To determine total amino acids, the method involves alkaline hydrolysis of the proteins with sodium hydroxide at 120 °C for 4 h in the absence of air. Best results were achieved with a SS Exil ODS column 5 μm (25 cm × 0.46 cm i.d.), with an eluent of methanol: 40 mM sodium acetate buffer (adjusted to pH 4.5 with acetic acid; 20:80, v/v), a flow rate of 0.80 mL/min at 26 °C, and with programmable fluorescence detection. Under optimum conditions excellent linearity was obtained, and the overall recovery was 90.5, and 95.9% for total tryptophan and tyrosine, respectively. The precision results showed that the relative standard deviation of the repeatability and reproducibility were ≤4.78 and ≤4.65, respectively. This method was used to quantify the cited analytes in the protein concentrate obtained during the lactic acid fermentation of shrimp waste.

Free tryptophan/large neutral amino acids ratios in blood plasma do not predict cerebral spinal fluid tryptophan concentrations in interleukin-1-induced anorexia

Peripheral administration of interleukin-1 (IL-1) reduces food intake and affects brain serotonergic activity, suggesting a causal relationship. Furthermore, IL-1 increases the brain concentrations of the serotonin precursor, tryptophan (TRP), by unclear mechanism(s). We aimed at confirming the link between IL-1 administration, raised brain TRP concentrations and the development of anorexia, and at investigating the mechanisms of TRP entry into the brain. Thirty adult, overnight fasted Sprague–Dawley rats were randomly assigned to i.p. injections of 1 μg/kg BW of IL-1α ( n = 10) or vehicle ( n = 10), or to pair-feeding with IL-1 animals ( n = 10). After 2 h, food intake, blood plasma concentrations of total TRP, free TRP, large neutral amino acids (LNAA; competing with TRP for brain entry) were measured. Cerebral spinal fluid (CSF) TRP concentrations were also measured. TRP brain availability was assessed by calculating the plasma ratio free TRP/LNAA. Following IL-1 injection, food intake significantly declined in IL-1 rats, which was paralleled by decreased plasma free TRP and increased plasma LNAA. Despite a decrease in the free TRP/LNAA ratios in plasma, IL-1 significantly increased concentrations of TRP in CSF. These data show that the acute peripheral administration of IL-1 induces anorexia and raises CSF TRP levels. Considering the possible role of the raised CSF TRP in influencing brain serotonin activity, it is postulated that increased serotonergic neurotransmission could be involved in IL-1 induced anorexia.

Inhibition of tryptophan pyrrolase activity in restraint female rats following medroxyprogesterone administration.

To determine the effects of Medroxyprogesterone (hormonal contraceptive) in restraint stressed female rats in relation to tryptophan metabolism. Pre-clinical study. Department of Biochemistry, University of Karachi. The investigation was carried out in the year 2003. Female Albino Wistar rats (150-200 gm body wt) were selected and divided into four groups (n=5 in each group). Rats were injected intraperitoneally either vehicle or Medroxyprogesterone (25mg/kg/ml) and were immediately subjected to 2 hours restraint stress while respective controls remained in their home cages. In restraint stress group, hepatic holo and total tryptophan pyrrolase activities were increased. Liver tryptophan, total serum tryptophan and albumin concentration were decreased. Brain tryptophan, 5HT and 5HIAA concentrations were increased. Medroxyprogesterone administration in unrestraint rats inhibited holo, total and apo enzyme activities with increases in liver tryptophan concentrations. Effect of restraint stress following Medroxyprogesterone administration when compared with drug injected unrestrained group showed increase in holo and total tryptophan pyrrolase activities with decrease in liver tryptophan concentrations. Brain tryptophan, 5HT and 5HIAA levels were increased. Results when compared with vehicle injected stressed-rats showed that total and apo tryptophan pyrrolase activities were decreased. Liver tryptophan, serum tryptophan and albumin concentrations were increased but brain tryptophan metabolism was not effected. It is concluded that Medroxyprogesterone inhibits stress induce increases in peripheral tryptophan metabolism and increases plasma tryptophan. Although stress induced increases in brain indoles were not effected by the drug at two hours, further studies on time course effects of this drug will be needed to explore its possible anxiolytic effects.

Menopause alters the metabolism of serum serotonin precursors and their correlation with gonadotropins and estradiol

Objective Tryptophan, the serotonin (5-HT) precursor, is circulating in blood in both free (FT) and protein-bound forms. The free form crosses the hematoencephalic barrier and is converted into 5-HT. During the fertile years, tryptophan levels are negatively correlated to gonadotropin concentrations. The present study aims to evaluate the correlation between circulating tryptophan, gonadotropin and estradiol (E2) levels postmenopause.Methods Serum levels of total tryptophan (TT, free + protein-bound) and FT, and plasma luteinizing hormone (LH), follicle stimulating hormone (FSH), and E2 were determined in 15 postmenopausal women and 15 cycling women during follicular (days 7–10), periovulatory (days 13–16) and luteal (days 21–24) phases of the menstrual cycle. Data were analyzed by ANOVA, linear correlation coefficients and hierarchical cluster analysis of variables.Results TT, but not FT, levels were significantly (p < 0.05) higher in postmenopausal (12.07 ± 0.40 µg/ml) than fertile women in the periovulatory period (10.46 ± 0.36 µg/ml). In postmenopausal women, there was no significant correlation between TT and FT, nor between these tryptophan forms and gonadotropins, but only between FT and E2. Cluster analysis showed that the main cluster composed by FSH–LH–TT–FT observed in fertile women was absent in postmenopause, since both serum tryptophan forms were distant from gonadotropins.Conclusion High TT levels circulate in postmenopausal women, with lack of correlation between TT and FT, and FT/TT and gonadotropins. Since estrogens play a pivotal role on central 5-HT metabolism, estrogen deprivation may alter the brain tryptophan utilization for 5-HT synthesis and its relation to gonadotropin release.

Studies on the tryptophan requirement of lactating sows. Part 1: Estimation of the tryptophan requirement by performance

Mature sows were evenly assigned to six dietary treatments, which differed only in the concentration of total (apparent ileal digestible, AID) tryptophan (Trp) amounting per kg feed to 1.2 g (0.8 g) to 4.2 g (3.8 g) in diets 1-6. For a total of 72 lactations (28 days) sows' feed intake was measured daily and body weight was measured on day 110 of pregnancy and on days 1 and 28 of lactation. Litter size was standardized to 10-12 piglets within 1 week after farrowing. The piglets were weighed at days 1, 21 and 28. Milk yield was recorded by the weigh-suckle-weigh method on days 20 and 21. Concentrations of milk fat and protein were measured in manually drawn samples (days 20 and 21) by infrared spectroscopy. Average daily feed intake of the sows was 3.4, 4.7, 4.7, 6.1, 5.1 and 4.7 kg (diets 1-6 respectively, p < 0.001). Body weight losses of the sows during lactation were 30.8, 16.9, 19.2, 9.5, 14.1 and 13.1 kg (diets 1-6 respectively, p < 0.05). Milk output in the average of days 20 and 21 was 6840, 8192, 8362, 9035, 8618 and 8140 g/day, respectively (p < 0.01). There were no differences in milk fat or protein contents. Daily weight gain of the piglets in the average of lactation was 157, 184, 184, 187, 185 and 177 g, respectively (p < 0.10). Based on the results of this study the estimated Trp requirement of lactating sows for optimal performance was calculated with 1.9 g AID Trp/kg in the lactation diet (according to 2.0 g true ileal digestible Trp and approximately 2.6 g Trp on total basis).