The low level of 5-hydroxytryptophan decarboxylase in human brain

Robins, Eli; Robins, James M.; Croninger, Adele B.; Moses, Sylvia G.; Spencer, Sylvia J.; Hudgens, Richard W.

doi:10.1016/0006-2944(67)90010-5

Cited by 74 publications

(14 citation statements)

References 18 publications

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“…There is no evidence that vitamin B6 deficiency will cause inhibition of human brain 5-hydroxytryptophan decarboxylase, and indeed this enzyme is little affected in the vitamin B6deficient rat, although the liver and kidney enzymes show impaired activity (Davis, 1963). However, there may be a problem of species difference here, because although the decarboxylation step is not the rate-limiting reaction for 5-hydroxytryptamine synthesis in the rat, there is some evidence that it may be in the human (Robins, Robins, Croninger, Moses, Spencer, and Hudgens, 1967).…”

Section: Depressionmentioning

confidence: 95%

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

Rose¹

1972

J Clin Pathol

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In recent years, considerable interest has been developed in the effect of various diseases upon the metabolic pathway by which L-tryptophan is converted to nicotinic acid derivatives. As the list of diseases associated with abnormal tryptophan metabolism has grown, there has been mounting scepticism abc;ut the specificity and clinical significance of many of the observed changes. The aim of this article is to review some of the more recent developments which have taken place in the study of tryptophan metabolism in man, and to show that many of the reported abnormalities may have as their origin the influence of hormonal and nutritional factors upon the metabolic pathway. Recognition of these factors should help to distinguish between non-specific changes brought about by the metabolic response to the 'stress' of any severe illness, and abnormalities of tryptophan metabolism that are of pathological or clinical significance.Clinical research into tryptophan metabolism in man has been largely concerned with the levels of intermediate metabolites that are present in urine collected after the patient has received an oral dose of L-tryptophan. The techniques involved have been discussed by Price, Brown, and Yess (1965), and by Musajo and Benassi (1964), who also reviewed the published results obtained in a variety of diseases. Biochemistry of Tryptophan Metabolism and the Effect of HormonesThe steps involved in the biosynthesis of nicotinic acid and 5-hydroxytryptamine from L-tryptophan are summarized in Figure 1. Some of these enzymatic reactions require pyridoxal 5-phosphate, the coenzyme derived from the various forms of vitamin B6, as a cofactor. Impaired function of this coenzyme results in an elevated urinary excretion ofkynurenine, 3-hydroxykynurenine, and xanthurenic acid, apparently because the kynureninase which is responsible for the conversion of 3-hydroxykynurenine

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Section: Depressionmentioning

confidence: 95%

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

Rose¹

1972

J Clin Pathol

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“…Each value is the mean of triplicate determinations. human brain (Robins et al, 1967;Lloyd and Hornykiewicz, 1970;Sacks et al, 1979).…”

Section: Discussionmentioning

confidence: 99%

Aromatic l‐Amino Acid Decarboxylase Activity of the Rat Retina Is Modulated In Vivo by Environmental Light Maria Hadjiconstantinou

Rossetti

Silvia

Krajnc

et al. 1988

Journal of Neurochemistry

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Aromatic L-amino acid decarboxylase (AAAD) activity of rat retina is low in animals placed in the dark. When the room lights are turned on, activity rises for almost 3 h and reaches values that are about twice the values found in the dark. A study of the kinetics of the enzyme revealed that the apparent Km values for L-3,4-dihydroxyphenylalanine and pyridoxal-5'-phosphate were unchanged in light- and dark-exposed animals, whereas the Vmax increased in the light. Treating the animals with cycloheximide before exposure to light prevented the increase of enzyme activity. Immunotitration with antibodies to AAAD suggested that more enzyme molecules are present in the light than in the dark. When the room lights are turned off AAAD activity drops rapidly at first and then more slowly, suggesting that at least two processes are responsible for the fall of enzyme activity. Exposure to short periods of dark followed by light results in a rapid increase of AAAD activity. Mixing homogenates from light- and dark-exposed rats results in activity values that are less than expected, suggesting the presence of an endogenous inhibitor(s). These studies demonstrate that AAAD activity is modulated in vivo.

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“…The human brain contains less AADC activity than the rodent brain (Robins et al, 1967), and following degeneration of the nigrostriatal DA pathway, AADC may well become rate-limiting, especially for the conversion of 3,4-dihydroxyphenylalanine (l-dopa) to DA. In Parkinson's disease, degeneration of the nigrostriatal system is accompanied by depletion of DA and marked reductions in striatal TH and AADC activities (Lloyd and Hornykiewicz, 1970).…”

Section: Introductionmentioning

confidence: 99%

Reciprocal regulation of the content of aromatic L-amino acid decarboxylase and tyrosine hydroxylase mRNA by NGF in PC12 cells

Jin

Juorio

et al. 1997

J. Neurosci. Res.

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Aromatic L‐amino acid decarboxylase (AADC) and tyrosine hydroxylase (TH) are involved in the synthesis of dopamine and other monoamine neurotransmitters, and their activities can be regulated by a number of physiological stimuli. An interesting finding has been that (−)‐deprenyl and some other irreversible monoamine B oxidase inhibitors increase AADC gene expression and that these compounds can exert neuronal protection/rescue effects. In this study, we have investigated the effects of nerve growth factor (NGF), and of (−)‐deprenyl on AADC and TH Gene expression in PC12 cells. Cells were treated with different doses of NGF (0.2–50 ng/ml) for up to 3 days. Northern and blot hybridizations were performed to detect AADC and TH mRNA. The results show that NGF can down‐regulate AADC gene expression while increasing TH gene expression in a time‐ and dose‐dependent fashion. Treatment with (−)‐deprenyl alone increases the gene expression of AADC, and (−)‐deprenyl further counteracts the reductions induced by NGF. This study introduces novel results with regard to the regulation of the gene expression of AADC in PC12 cells, which is not paralleled by the other catecholamine biosynthetic enzymes. These findings support the existence of an interaction between NGF and AADC gene expression that may be associated with the process of neuronal degeneration or regeneration. J. Neurosci. Res. 47:449–454, 1997. © 1997 Wiley‐Liss, Inc.

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The low level of 5-hydroxytryptophan decarboxylase in human brain

Cited by 74 publications

References 18 publications

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

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

Aromatic l‐Amino Acid Decarboxylase Activity of the Rat Retina Is Modulated In Vivo by Environmental Light Maria Hadjiconstantinou

Reciprocal regulation of the content of aromatic L-amino acid decarboxylase and tyrosine hydroxylase mRNA by NGF in PC12 cells

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