Oxygen Affinity of Tyrosine and Tryptophan Hydroxylases in Synaptosomes

Katz, Ira R.

doi:10.1111/j.1471-4159.1980.tb03721.x

Cited by 33 publications

(10 citation statements)

References 15 publications

(11 reference statements)

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“…This may result in impairment of certain brain enzymes, among which we can highlight the tryptophan hydroxylase, whose main function is to participate in the synthesis of serotonin (Katz, 1980, Young, 2013. Thus, the hypoxia condition can decrease in serotonin production, resulting in in worsening to the mood of those who are exposed to this condition, which may be an explanation for the decrease in the mood of subjects in our study.…”

Section: Discussionmentioning

confidence: 99%

Exercise performed at hypoxia influences mood state and anxiety symptoms

Souza

Giampá

Lemos

et al. 2015

Motriz: rev. educ. fis.

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Abstract-During hypoxia conditions, psychological states can be worsened. However, little information is available regarding the effect of physical exercise performed in hypoxia conditions on mood state and anxiety symptoms. The aim of the present study was to elucidate the acute effect of moderate physical exercise performed at hypoxia on mood states and anxiety symptoms in healthy young subjects. Ten volunteers were subjected to the following conditions: a normoxic condition (NC) and a hypoxic condition (HC). They performed 45 min of physical exercise. Their anxiety symptoms and mood states were evaluated at the initial time point as well as immediately following and 30 and 60 min after the exercise session. Our results showed a significant increase in post-exercise anxiety symptoms and a significant decrease in mood scores immediately after and 30 min after exercise performed in the HC. Moderate physical activity performed at hypoxia condition increased post-exercise anxiety and worsened mood state.Keywords: physical activity, hypoxia, mood state, anxietyResumo-"Exercício realizado em hipóxia influencia o estado de humor e sintomas de ansiedade." Em condição de hipóxia o aspecto psicológico pode piorar, porém, ainda há pouca informação sobre a resposta do exercício físico realizado nestas condições sobre o estado de humor e os sintomas de ansiedade. O objetivo deste estudo foi investigar o efeito agudo do exercício físico moderado realizado em condição de hipóxia sobre o estado de humor e sintomas de ansiedade de jovens saudáveis. Dez voluntários foram submetidos a duas condições: Condição Normóxia (CN) e Condição Hipóxia (CH) e realizaram 45' de exercício físico. Os sintomas de ansiedade e humor foram avaliados no momento basal, imediatamente após, 30 e 60 minutos. Observou-se um aumento significativo dos sintomas de ansiedade pós-exercício físico e uma redução significativa dos escores de humor em condição de hipóxia imediatamente e após 30 minutos de exercício. O exercício físico moderado realizado em condição de hipóxia promove uma resposta ansiogênica pós-exercício físico e piora do estado de humor. Palavras-chave: exercício físico, hipóxia, estado de humor, ansiedadeResumen-" El ejercicio realizado en la hipoxia influencias estado de ánimo y síntomas de ansiedad." En condiciones de hipoxia , los estados psicológicos pueden empeorar . Sin embargo, hay poca información disponible sobre el efecto del ejercicio físico realizado en condiciones de hipoxia en los síntomas del estado de ánimo y de ansiedad. El objetivo del presente estudio fue determinar el efecto agudo del ejercicio físico moderado realizado en hipoxia en los estados de ánimo y los síntomas de ansiedad en los sujetos jóvenes sanos. Diez voluntarios se sometieron a las siguientes condiciones : una condición de normoxia ( NC ) y una condición hipóxica ( HC ). Realizaron 45 min de ejercicio físico. Sus síntomas de ansiedad y los estados de ánimo fueron evaluados en el momento inicial , así como inmediatamente después y 30 y 60 minutos después de ...

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Section: Discussionmentioning

confidence: 99%

Exercise performed at hypoxia influences mood state and anxiety symptoms

Souza

Giampá

Lemos

et al. 2015

Motriz: rev. educ. fis.

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“…Reduced brain noradrenaline after hypoxia has also been found (Hayashi et al, 1990). Reported TH Km-values for O2 vary from 3-24 μM (Fisher and Kaufman, 1972;Fitzpatrick, 1991;Ikeda et al, 1966;Katz, 1980;Numata et al, 1977). Although the O2 concentration in brain, kidney and liver tissue of living animals is uncertain (Feinsilver et al, 1987;Rolett et al, 2000), it is likely that at sea level the tissue partial pressures of oxygen may get close to the Kmlevels suggested for rat TH and be rate limiting.…”

Section: A Possible Role Of Th In Hypoxia Induced Diseasementioning

confidence: 92%

Oxygen dependence of tyrosine hydroxylase

et al. 2007

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The effects of dioxygen on tyrosine hydroxylase (TH) activity was studied, measuring the formation of DOPA from tyrosine, (3)H(2)O from 3,5-(3)H-tyrosine, or by direct oxygraphic determination of oxygen consumption. A high enzyme activity was observed during the initial 1-2 min of the reactions, followed by a decline in activity, possibly related to a turnover dependent substoichiometrical oxidation of enzyme bound Fe(II) to the inactive Fe(III) state. During the initial reaction phase, apparent K (m)-values of 29-45 microM for dioxygen were determined for all human TH isoforms, i.e. 2-40 times higher than previously reported for TH isolated from animal tissues. After 8 min incubation, the K (m) (O(2))-values had declined to an average of 20 +/- 4 microM. Thus, TH activity may be severely limited by oxygen availability even at moderate hypoxic conditions, and the enzyme is rapidly and turnover dependent inactivated at the experimental conditions commonly employed to measure in vitro activities.

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“…In addition to tryptophan it uses oxygen molecules as a substrate to provide the oxygen atom in the hydroxyl group in serotonin. Katz 4 determined the Km for oxygen for the enzyme in rat brain synaptosomes to ensure that the medium surrounding the enzymes was as close to physiologic as possible. The Km varied with the concentration of tryptophan.…”

Section: The Role Of Oxygen In the Regulation Of Biogenic Amine Synthmentioning

confidence: 99%

“…4 As a result, at lower tryptophan levels the affinity of tryptophan hydroxylase for oxygen will be less than at higher tryptophan levels. If the regulation of tryptophan hydroxylase in humans is similar, this has implications for depressed patients with mild hypoxia.…”

Section: Possible Clinical Implicationsmentioning

confidence: 99%

Elevated incidence of suicide in people living at altitude, smokers and patients with chronic obstructive pulmonary disease and asthma: possible role of hypoxia causing decreased serotonin synthesis

Young

2013

J Psychiatry Neurosci

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Oxygen Affinity of Tyrosine and Tryptophan Hydroxylases in Synaptosomes

Cited by 33 publications

References 15 publications

Exercise performed at hypoxia influences mood state and anxiety symptoms

Exercise performed at hypoxia influences mood state and anxiety symptoms

Oxygen dependence of tyrosine hydroxylase

Elevated incidence of suicide in people living at altitude, smokers and patients with chronic obstructive pulmonary disease and asthma: possible role of hypoxia causing decreased serotonin synthesis

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