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Tryptophan Depletion (tryptophan + depletion)

Distribution by Scientific Domains

Medical Sciences	90%

Kinds of Tryptophan Depletion

rapid tryptophan depletion

Selected Abstracts

Effect of Tryptophan Depletion on Alcohol Cue-Induced Craving in Abstinent Alcoholic Patients

ALCOHOLISM, Issue 8 2001
Ismene L. Petrakis
Background: The capacity of alcohol cues to precipitate the desire to drink may be an important determinant of relapse to alcohol use in recovering alcohol-dependent patients. This study evaluated whether attenuation of serotonin synthesis via depletion of its precursor tryptophan reduces the magnitude of cue-induced craving for alcohol in recently abstinent alcoholic individuals. Methods: Alcohol-dependent patients (n= 16), 1 to 3 months after detoxification, who exhibited a 20% or greater increase in reported craving when presented with an alcoholic beverage, completed two additional alcohol cue-exposure test days, 1 week apart. Each cue exposure was preceded by administration of a concentrated amino acid drink that resulted in a rapid and significant decline in plasma free tryptophan (active depletion, no tryptophan supplementation) or a similar drink containing tryptophan (placebo depletion). Tests were conducted in a randomized, double-blind fashion. Results: There were no significant changes in the magnitude of cue-induced craving with active tryptophan depletion compared with placebo. Conclusions: These data question the dependence of alcohol cue-induced craving in sober alcoholics on the ongoing synthesis of serotonin. [source]

Patients with a major depressive episode responding to treatment with repetitive transcranial magnetic stimulation (rTMS) are resistant to the effects of rapid tryptophan depletion

DEPRESSION AND ANXIETY, Issue 8 2007
John P. O'Reardon M.D.
Abstract Repetitive transcranial magnetic stimulation (rTMS) appears to be efficacious in the treatment of major depression based on the results of controlled studies, but little is known about its antidepressant mechanism of action. Mood sensitivity following rapid tryptophan depletion (RTD) has been demonstrated in depressed patients responding to SSRI antidepressants and phototherapy, but not in responders to electroconvulsive therapy (ECT). We sought to study the effects of RTD in patients with major depression responding to a course of treatment with rTMS. Twelve subjects treated successfully with rTMS monotherapy underwent both RTD and sham depletion in a double-blind crossover design. Depressive symptoms were assessed using both a modified Hamilton Depression Rating Scale (HDRS) and Beck Depression Inventory (BDI). The differential change in depression scores across the procedures was compared. No significant difference in mood symptoms was noted between RTD and the sham-depletion procedure on either continuous measures of depression, or in the proportions of subjects that met predefined criteria for a significant degree of mood worsening. Responders to rTMS are resistant to the mood perturbing effects of RTD. This suggests that rTMS does not depend on the central availability of serotonin to exert antidepressant effects in major depression. Depression Anxiety 24:537,544, 2007. © 2006 Wiley-Liss, Inc. [source]

Effects of serotonin and catecholamine depletion on interleukin-6 activation and mood in human volunteers

HUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 6 2002
Ben J. Harrison
Abstract There is increasing evidence that depression and related neurotic illnesses are associated with alterations in immune function that may contribute to their pathogenesis. For example, clinical and experimental studies have shown that abnormal HPA-axis activation and monoamine neurotransmission may be related to an increased release of proinflammatory cytokines from stimulated lymphocytes in the periphery and brain. In the present investigation, the effects of tryptophan depletion (TD) on unstimulated plasma interleukin-6 (IL-6) concentrations were investigated in order to determine whether acute changes in serotonin (5-HT) neurotransmission would induce a proinflammatory response in healthy individuals. The effects of TD were compared with the analogous procedure of tyrosine depletion (TPD), which reduces catecholamine metabolism in humans. Thirteen female participants completed three experimental sessions: TD, TPD and a balanced-control condition (B). Mood-ratings and blood sampling were performed at baseline and 5,h after the administration of the mixtures. Analyses revealed that TD and TPD markedly reduced tryptophan and tyrosine/phenylalanine levels, respectively. No changes in plasma IL-6 production or ratings of lowered mood were observed, however, subjects did report feeling more fatigued after TD. These findings indicate that a transient disruption in global monoamine function does not stimulate a proinflammatory response of IL-6 in normal volunteers. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Tryptophan metabolism and oxidative stress in patients with Huntington's disease

JOURNAL OF NEUROCHEMISTRY, Issue 3 2005
N. Stoy
Abstract Abnormalities in the kynurenine pathway may play a role in Huntington's disease (HD). In this study, tryptophan depletion and loading were used to investigate changes in blood kynurenine pathway metabolites, as well as markers of inflammation and oxidative stress in HD patients and healthy controls. Results showed that the kynurenine : tryptophan ratio was greater in HD than controls in the baseline state and after tryptophan depletion, indicating increased indoleamine dioxygenase activity in HD. Evidence for persistent inflammation in HD was provided by elevated baseline levels of C-reactive protein, neopterin and lipid peroxidation products compared with controls. The kynurenate : kynurenine ratio suggested lower kynurenine aminotransferase activity in patients and the higher levels of kynurenine in patients at baseline, after depletion and loading, do not result in any differences in kynurenic acid levels, providing no supportive evidence for a compensatory neuroprotective role for kynurenic acid. Quinolinic acid showed wide variations in blood levels. The lipid peroxidation data indicate a high level of oxidative stress in HD patients many years after disease onset. Levels of the free radical generators 3-hydroxykynurenine and 3-hydroxyanthranilic acid were decreased in HD patients, and hence did not appear to contribute to the oxidative stress. It is concluded that patients with HD exhibit abnormal handling of tryptophan metabolism and increased oxidative stress, and that these factors could contribute to ongoing brain dysfunction. [source]

Can Serotonin Transporter Genotype Predict Craving in Alcoholism?

ALCOHOLISM, Issue 8 2009
Nassima Ait-Daoud
Background:, We hypothesize that functional control of the serotonergic system is regulated in part by differential expression of the serotonin (5-HT) transporter (5-HTT). Alcohol-dependent individuals with the LL/LS genotype (L-carriers), compared with those with the SS genotype, have a lower 5-HT neurotransmission, which we hypothesize would be associated with higher craving for alcohol among L-carriers. We hypothesize further that acute peripheral depletion of tryptophan (5-HT's precursor), while further reducing 5-HT function, might decrease auto-inhibition of 5-HT neuronal firing, thereby increasing 5-HT neurotransmission transiently and lowering alcohol craving. Methods:, We tested these hypotheses by examining whether in 34 Hispanic alcohol-dependent individuals subjective and physiological cue craving for alcohol differed by genotype, age of onset of problem drinking, and tryptophan availability. Results:, On subjective "urge to drink" and "crave for a drink," we found a significant (p < 0.05) main effect of genotype and cue, as well as an interaction among genotype, age of onset of problem drinking, and tryptophan depletion. For the physiological measure of pulse, there was a main effect of genotype. L-carriers had higher craving than their SS counterparts, an effect that decreased under tryptophan depletion. While craving in L-carriers increased with an earlier age of onset of problem drinking, the opposite effect was seen in those with the SS genotype. Conclusion:, These results not only provide support for the hypothesis that alcoholics who are L-carriers have greater alcohol craving and possibly greater propensity for drinking but also propose that there is an important 5-HTT gene-by-environment interaction that alters cue craving response for alcohol. [source]

Rapid tryptophan depletion reverses phenelzine-induced suppression of REM sleep

JOURNAL OF SLEEP RESEARCH, Issue 1 2003
Hans-Peter Landolt
SUMMARY Treatment with the monoamine oxidase inhibitor phenelzine completely suppressed rapid eye movement (REM) sleep in five depressed patients. Hypothesizing that increased serotonergic neurotransmission eliminated REM sleep, we administered a tryptophan-free amino acid drink (TFD) known to reduce plasma tryptophan and brain levels of serotonin. The TFD reversed the REM sleep suppression, while the control drink (TFD plus tryptophan) had virtually no effect on sleep. Neither TFD nor control drink affected mood, total sleep time, sleep efficiency or the all-night electroencephalogram power spectra in non-rapid eye movement (NREM) sleep. We report the first non-disruptive, double-blind method for studying human subjects overnight with and without REM sleep. It opens up a novel strategy for investigating the functions of REM sleep, and the roles of serotonin and REM sleep in the regulation of NREM sleep and mood. [source]

Effect of Tryptophan Depletion on Alcohol Cue-Induced Craving in Abstinent Alcoholic Patients

Rapid tryptophan depletion as a treatment for acute mania: a double-blind, pilot-controlled study

BIPOLAR DISORDERS, Issue 8 2007
Julia Applebaum
Objectives:, Rapid reduction of up to 80% in plasma tryptophan level can be accomplished by administering an oral tryptophan-free amino acid solution, which induces hepatic protein synthesis and thereby depletes available plasma tryptophan. Rapid tryptophan depletion (RTD) has been shown to induce transient depressive symptoms in patients with remitted major depression. The effect of RTD in acutely manic patients has not been studied. Methods:, We carried out a double-blind, placebo-controlled pilot study of RTD in acutely manic patients. Patients were randomized to the treatment groups. Sodium valproate treatment was started at a dose of 1000 mg/day and continued throughout the 7-day study. On days 1-7, patients received a daily tryptophan-free amino acid drink or a placebo drink. The tryptophan-free amino acid drink contained a mix of amino acids without tryptophan. The placebo drink contained the additives and constituents of the real mixture to provide identical flavor and texture without the amino acids. Ratings were administered at baseline and then repeated on days 3, 5, and 7. All ratings were carried out by an experienced rater who was blind to the group assignment of patients. Results:, A total of 23 patients entered the study and 17 completed the 7-day treatment protocol. The patients who received the amino acid drink showed greater improvement in mania ratings. The differences in Young Mania Rating Scale (YMRS) and Clinical Global Impression (GCI) scores were significant. However, the intolerance rate was high (23%) and the findings in this pilot study are based only on results from those patients who were able to tolerate the drink. Conclusions:, Rapid tryptophan depletion may have an antimanic effect. [source]

Nutritional manipulation and psychiatric conditions: focus on mood and cognition

ACTA NEUROPSYCHIATRICA, Issue 1 2003
W. J. Riedel
In this paper, several experimental models of human depression and cognitive dysfunction, which are designed specifically to mimic the proposed mechanisms of action of many nutritional supplements, are illustrated. These mechanisms of interest are antioxidant effects, glucose utilization, neuronal membrane function and neurotransmitter effects, with particular reference to nutrient-based amino acid manipulations of neurotransmission, such as tryptophan depletion. It is concluded that the application of experimental human models of altered mood and cognitive function may illuminate substantially the quest for nutritional enhancement of human mood and cognitive function. [source]