Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A pronounced and irreversible depression of the erythroid and liver delta-aminolevulinate dehydratase (porphobilinogen synthase; 5-aminolevulinate hydro-lyase, EC 4.2.1.24) activity was observed in rats exposed to trichloroethylene, a widely used solvent. The depression could not be restored after the treatment with dithiothreitol and zinc; however, radioimmunoassay of delta-aminolevulinate dehydratase indicated that trichloroethylene exposure did not essentially decrease the amount of enzyme. The depression of the enzyme activity thus proved to be due not to a reduction in the enzyme amount but to enzyme inhibition. The purified holoenzyme (fully activated delta-aminolevulinate dehydratase with 1 atom zinc per subunit) and apoenzyme (fully activated enzyme with the remaining zinc less than 0.1 atom per subunit) were prepared to investigate the in vitro inhibition of the enzyme by trichloroethylene. Incubation with trichloroethylene did not inhibit the holoenzyme, but inhibited the apoenzyme dose-dependently. Trichloroethylene inhibited the holoenzyme when incubated with the mixed function oxidase system. The in vitro experiments reported here indicate two mechanisms of the enzyme inhibition by trichloroethylene. In the liver of rats exposed to trichloroethylene, cytochrome P-450 concentration and heme saturation of tryptophan pyrrolase (EC 1.13.11.11) are reduced; in addition, the activity of delta-aminolevulinate synthase (EC 2.3.1.37) increased. After exposure to trichloroethylene at 2.14 g/m3, urinary delta-aminolevulinic acid increased to 142% of the control, while the excretion of coproporphyrin was reduced to 19.6% of the control.
 ...
PMID:Inhibition of delta-aminolevulinate dehydratase in trichloroethylene-exposed rats, and the effects on heme regulation. 674 80

Duration and intensity of drug action are greatly influenced by the rates of which drugs are biotransformed by the cytochrome P-450-linked monooxygenase systems of the hepatic endoplasmic reticulum. Several interferon-inducing agents (poly rI.rC, tilorone, vaccines, viruses, endotoxin) are shown to markedly depress hepatic P-450 systems when administered to rodents. The interferon (IF) inducers that depress hepatic drug metabolism also modulate certain immune responses; it is therefore not known whether the depression of P-450 is due to IF per se or to the action of IF-inducing agents on one or more components of the immune system. The loss of cytochrome P-450 elicited by IF-inducing agents is accompanied by a perturbation of heme metabolism associated with the dissociation of heme from cytochrome P-450. The agents also cause losses of hepatic catalase and tryptophan 2,3-dioxygenase. These studies predict that viral infections, vaccinations, and treatment with IF-inducing agents will be shown to seriously impair the metabolism of drugs in humans.
 ...
PMID:Effects of interferon-inducing agents on hepatic cytochrome P-450 drug metabolizing systems. 694 Apr 67

One million American adolescents are currently using oral contraceptives. Sixty percent of those beginning the pill discontinue its use within a year. Concern that mood change might be contributing to the decision to stop the pill prompted a review of the literature on the association between oral contraceptive use and depression. Trends in adolescent pregnancy, contraceptive use, and compliance are discussed in the first section. In the second, 12 clinical studies are analyzed. Because there are no studies of mood change and oral contraceptive use in adolescents, some data from adults are presented. Biochemical theories to explain an association between oral contraceptive use and depression are discussed in section three. Nine of the 12 clinical studies reported depression in 16-56% of women using oral contraceptives. Three studies found no association between oral contraceptive use and depression. The major problems found in the clinical trials were selection bias, poor assessment of pre-therapeutic mood state and unclear definition or measurement of depression. Current biochemical research suggests that oral contraceptives induce tryptophan oxygenase, which leads to pyridoxine deficiency in some women. However, the use of pyridoxine to prevent or treat depression in women taking oral contraceptives requires further study.
 ...
PMID:Oral contraceptives and depression: impact, prevalence and cause. 703 18

Serotonin and nicotinic acid ribonucleotide metabolic pathways of tryptophan metabolism were studied before and after tryptophan load test in thirty women using oral contraceptive steroids for a period of 2 to 5 years. Ten of them were suffering from depression. Another ten healthy women participated in this study as a control group. Twenty-four-hour urinary excretion of serotonin, 5-hydroxyindole acetic acid and total 5-hydroxyindoles were estimated as indices of serotonin pathway metabolites, while xanthrenate excretion was determined as an index of tryptophan oxygenase pathway. Plasma cortisol, urinary 17-oxosteroids and 17-hydroxycorticosteroids were determined to assess adrenal cortical function. Urinary creatinine output was assayed to check the adequacy of 24-hr urine collection. The changes induced by oral contraceptive steroids on tryptophan and corticosteroid metabolism were correlated with the associated depression. Changes in serotonin metabolism were demonstrated in the depression group before and after tryptophan load test, while in the non-depression group before and after tryptophan load test, while in the non-depression group, these changes were only demonstrated after tryptophan load test. Results indicated the alteration in tryptophan metabolism are usually well compensated in the non-depression group but may accentuate or precipitate the development of depression in susceptible women.
 ...
PMID:Serotonin metabolism and depression in oral contraceptive users. 714 Feb 95

Plasma 5-hydroxytryptamine (serotonin), tryptophan, neopterin and cortisol levels were measured in patients with depressive cancer cachexia and in healthy controls during the same time period. Patients with advanced cancers had significantly raised neopterin, a marker of endogenous gamma-interferon (IFN-gamma) production, and cortisol values, but decreased serotonin and tryptophan levels. Much work has been done to elucidate the possible role of serotonin in depressive states. IFN-gamma induces a high level of indoleamine dioxygenase (IDO), a tryptophan degrading enzyme, and high cortisol levels induce high tryptophan oxygenase activity, which in turn increases metabolism along the tryptophan-nicotinic acid pathway. These results suggest that persistent immune activation and intense adrenal activity occur in patients with cancer cachexia, resulting in disorders involving tryptophan metabolism followed by depression in cancer cachexia.
 ...
PMID:Cancer cachexia and depressive states: a neuro-endocrine-immunological disease? 928 72

This paper reviews the preclinical and clinical evidence regarding the use of the dietary supplement 5-hydroxytryptophan (5-HTP) for the treatment of depression. In the absence of supplementation with exogenous 5-HTP, the amount of endogenous 5-HTP available for serotonin synthesis depends on the availability of tryptophan and on the activity of various enzymes, especially tryptophan hydroxylase, indoleamine 2,3-dioxygenase, and tryptophan 2,3-dioxygenase (TDO). Factors affecting each of these are reviewed. The amount of 5-HTP reaching the central nervous system (CNS) is affected by the extent to which 5-HTP is converted to serotonin in the periphery. This conversion is controlled by the enzyme amino acid decarboxylase, which, in the periphery, can be blocked by peripheral decarboxylase inhibitors (PDIs) such as carbidopa. Preclinical and clinical evidence for the efficacy of 5-HTP for depression is reviewed, with emphasis on double-blind, placebo-controlled (DB-PC) trials. Safety issues with 5-HTP are also reviewed, with emphasis on eosinophilia myalgia syndrome (EMS) and serotonin syndrome.
 ...
PMID:Serotonin a la carte: supplementation with the serotonin precursor 5-hydroxytryptophan. 1602 17

Compounds targeting the individual enzymes of kynurenine-nicotinamide pathway have led to new neuropharmacological concepts and provide novel opportunities for therapeutic intervention. Tryptophan pyrrolase (Tryptophan-2, 3-dioxygenase; EC 1.13.11.11), a metalloprotein, is the first and rate limiting enzyme of the most important pathway for tryptophan metabolism via kynurenine-nicotinamide pathway in the liver and therefore plays a key role in regulating the physiological flux of tryptophan in to relevant metabolic pathways like synthesis of neurotransmitter, serotonin in the brain. Fluoxetine, a clinically proven antidepressant, have shown statistically significant inhibition of hepatic tryptophan pyrrolase activities (holo, total and apo form) in both the sexes of rats at 10 & 30 mg/kg doses. Despite elevated holo-enzyme form of tryptophan pyrrolase in female rats, we have found similar inhibition of tryptophan pyrrolase activity by fluoxetine hydrochloride in both male and female rats. The results are discussed in relation to gender differences in the enzyme activity and its possible role in pathophysiology of depression in females.
 ...
PMID:Similar pattern of inhibition of tryptophan pyrrolase activity by fluoxetine hydrochloride in both sexes of rats. 1641 76

Hepatic tryptophan 2,3-dioxygenase (TDO) is one of the rate-limiting enzymes in tryptophan catabolism and plays an important role in regulating the physiological flux of tryptophan into relevant metabolic pathways. In this study, we determined the effect of the non-steroidal anti-inflammatory agents, tolmetin and sulindac, on rat liver TDO activity and the subsequent changes in the hippocampal and striatal neurotransmitter levels. The amount of melatonin produced by the pineal gland was also measured using high performance liquid chromatography (HPLC). Treatment of rats with tolmetin or sulindac (5 mg/kg/bd for 5 days) significantly inhibited liver TDO activity. The results show that whilst tolmetin and sulindac increase serotonin levels in the hippocampus, these agents also significantly reduce dopamine levels in the striatum. Tolmetin, but not sulindac, increased the amount of melatonin produced by the pineal gland. The results of this study suggest that whilst tolmetin and sulindac may be beneficial for patients suffering from depression, these agents also have the potential to induce adverse effects in patients suffering with neurological disorders such as Parkinson's disease.
 ...
PMID:Non-steroidal anti-inflammatory agents, tolmetin and sulindac, inhibit liver tryptophan 2,3-dioxygenase activity and alter brain neurotransmitter levels. 1695 80

Increased concentrations of kynurenine pathway metabolites have been reported by several groups for disorders involving psychosis, including schizophrenia and bipolar disorder. To identify components of the pathway that may be relevant as biomarkers or may underlie the etiology of psychosis, it is essential to characterize the extent of kynurenine pathway activation and to investigate known regulators of one of the key kynurenine-producing enzymes, tryptophan 2,3-dioxygenase (TDO2), previously shown in this laboratory to be increased commensurate with kynurenine in postmortem anterior cingulate brain tissue from individuals with schizophrenia. Using this same anterior cingulate sample set from individuals with schizophrenia, bipolar disorder, depression and controls (N=12-14 per group), we measured the precursor of kynurenine and two downstream products. The precursor, tryptophan, was significantly increased only in the schizophrenia group (1.54-fold the mean control value, p=0.02), and through substrate-induced activation, may be one cause of the increased kynurenine and kynurenine metabolites. This finding for tryptophan differs from some, but not all, previous reports and methodological reasons for the discrepancies are discussed. A product of kynurenine metabolism, 3-OH-anthranilic acid was also significantly increased only in the schizophrenia group (1.68-fold the mean control value, p=0.03). 3-OH-anthranilic acid is a reactive species with cytotoxic properties, although the threshold for such effects is not known for neurons. Analysis of major pre- and post-mortem variables showed that none were confounding for these between-group experimental comparisons. Nicotinamide, a pathway end product, did not differ between groups but was associated with cause of death (suicide) within the bipolar group (p=0.03).
 ...
PMID:Alterations in kynurenine precursor and product levels in schizophrenia and bipolar disorder. 1832

Aging itself is considered as a major risk factor of dementia. The prevalence of the Alzheimer's disease (AD) is increasing exponentially after the age of 65 and doubles every 5 years. The major aim of our present research was to examine the effect of aging on the transcription of certain genes associated with neurodegenerative disorders in the rat brain. The influence of the vasopressin (VP) hormone was also examined in the same experimental paradigm. Age dependent transcriptional changes of the following four genes were examined in the cerebral cortex: the first was the gene of the amyloid precursor protein (APP) which is abnormally cleaved to toxic beta-amyloid fragments. These aggregated peptides are the major components of the senile plaques in the AD brain. The second one was the mitogen-activated protein kinase (MAPK1) gene. The MAPK is involved in the abnormal hyperphosphorylation of the tau-protein which results in aggregated neurofibrillary tangles. The beta-actin gene was the third one. The protein product of this gene is considered to be involved in synaptogenesis, neuronal plasticity and clinical conditions like depression and AD. The last one was the gene of the tryptophan 2,3-dioxygenase (TDO2) enzyme. The activity of this enzyme is considered as a rate limiting factor in the metabolism of the neuro-immune modulator quinolinic acid (QUIN). The transciptional activity of young (2.5 months) and aged (13 months) Brattleboro rats with or without VP expression were compared by means of real time PCR technique. The cortical transciptional activity of the APP and TDO2 genes were increased in the aged animals as compared with the activity of the young ones, and this effect was independent on the presence of the VP. Our results indicate the importance of certain age dependent transcriptional changes might influence the mechanism of AD and other neurodegenerative disorders.
 ...
PMID:[The transcription of the amyloid precursor protein and tryptophan 2,3-dioxygenase genes are increased by aging in the rat brain]. 1983 74


1 2 Next >>