Calcium activation of brain tryptophan hydroxylase

Knapp, Suzanne; Mandell, Arnold J.; Bullard, W P

doi:10.1016/0024-3205(75)90076-4

Cited by 69 publications

(16 citation statements)

References 18 publications

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“…In contrast, other data suggest that Ca2+ directly inhibits TH in extracts of striatum . The results of this study, in agreement with other reports (Knapp et al, 1975;Lerner et al, 1977;Kapatos et al, 1982), indicate no direct effect of Ca2+ on striatal TH activity. However, Ca2+ does activate striatal TH in the presence of ATP and Mg2+.…”

Section: Discussionsupporting

confidence: 93%

Calcium, ATP, and Magnesium Activate Soluble Tyrosine Hydroxylase from Rat Striatum

1984

Journal of Neurochemistry

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Soluble tyrosine hydroxylase (TH) prepared from rat striatum by sonication, centrifugation, and gel filtration on Sephadex G-25 was activated by preincubation with Ca2+, ATP, and Mg2+. Activation occurred with micromolar concentrations of Ca2+ and required the presence of both ATP and Mg2+. The activation was reversible and was characterized by a large decrease of apparent Km for the pteridine cofactor and a small increase of Vmax. Ca2+-induced activation was small when TH activity was assayed at pH values near the optimum, but the magnitude of the activation increased with increasing assay pH. The activation apparently did not involve Ca2+-activated protease because it was not affected by the protease inhibitor leupeptin. Nor did it involve cyclic AMP-dependent protein kinase, as evidenced by the failure of the heat-stable inhibitor of this kinase to decrease Ca2+-induced TH activation. Furthermore, the activation of TH evoked by Ca2+ and that produced by cyclic AMP was additive. These experiments indicate that striatal TH can be activated in vitro by an endogenous Ca2+-dependent mechanism. The similarity of the Ca2+-induced activation of TH to that elicited by increased neuronal activity and terminal depolarization is discussed.

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Section: Discussionsupporting

confidence: 93%

Calcium, ATP, and Magnesium Activate Soluble Tyrosine Hydroxylase from Rat Striatum

1984

Journal of Neurochemistry

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“…nally based on studies of noradrenergic neurons in the vas deferens, medulla-pons, and cerebral cortex 19751). Subsequently, evidence in support of a similar hypothesis for serotonergic neurons was reported (Knapp et al, 1975;Hamon et al, 1977;Boadle-Biber, 1978), and the hypothesis was extended to dopaminergic terminals in striaturn .…”

Section: G Kapatos a N D M J Zigmondmentioning

confidence: 60%

Influence of Calcium on Dopamine Synthesis and Tyrosine Hydroxylase Activity in Rat Striatum

Kapatos

Zigmond

1982

Journal of Neurochemistry

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We have investigated three aspects of the relationship between calcium and tyrosine hydroxylase activity in rat striatum. In the first series of experiments, we examined the hypothesis that the rise in dopamine synthesis during increased impulse flow results from a calcium‐induced activation of tyrosine hydroxylase. Calcium (12.5–200 μM) had no effect when added to crude enzyme or enzyme partially purified by gel filtration. Moreover, incubation of synaptosomes with excess calcium (up to 3.5 mM) had little or no effect on dopamine synthesis. Incubation with the depolarizing alkaloid veratridine (75 μM) did increase dopamine synthesis, but did not alter the activity of tyrosine hydroxylase subsequently prepared from the synaptosomes, despite the presumed rise in intracellular calcium. In the second series we examined the hypothesis that increased dopamine synthesis after axotomy results from activation of tyrosine hydroxylase owing to a decrease in intracellular calcium. Addition of the calcium chelator EGTA (100 μM) to crude or partially purified enzyme was without effect, whereas incubation of synaptosomes with EGTA (500 μM) decreased cell‐free enzyme activity. In the third experimental series we examined the relationship between calcium and activation of tyrosine hydroxylase by dibutyryl cyclic AMP. EGTA failed to alter the increase in the activity of tyrosine hydroxylase prepared from synaptosomes incubated with dibutyryl cyclic AMP. However, it blocked the increase in synaptosomal dopamine synthesis and dopamine content normally produced by the cyclic AMP analogue. Thus, tyrosine hydroxylase does not appear to be activated by either increases or decreases in calcium availability. However, calcium may be important for the maintenance of basal tyrosine hydroxylase activity, and may play an indirect role in the expression of tyrosine hydroxylase activation produced by other means.

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“…Magnesium is necessary for tryptophan hydroxylase and serotonin receptor binding (Kantak, 1988) and is a potent antagonist of the N-methyl-D-aspartate (NMDA) receptor complex (Bresink et al, 1995). Calcium activates tryptophan hydroxylase in the synthesis of serotonin (Knapp et al, 1975). Iron is involved in the synthesis of neurotransmitters, including dopamine and serotonin (Beard et al, 1993).…”

Section: Discussionmentioning

confidence: 99%

Dietary patterns derived by reduced rank regression (RRR) and depressive symptoms in Japanese employees: The Furukawa nutrition and health study

Miki

Kochi

Kuwahara

et al. 2015

Psychiatry Research

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Calcium activation of brain tryptophan hydroxylase

Cited by 69 publications

References 18 publications

Calcium, ATP, and Magnesium Activate Soluble Tyrosine Hydroxylase from Rat Striatum

Calcium, ATP, and Magnesium Activate Soluble Tyrosine Hydroxylase from Rat Striatum

Influence of Calcium on Dopamine Synthesis and Tyrosine Hydroxylase Activity in Rat Striatum

Dietary patterns derived by reduced rank regression (RRR) and depressive symptoms in Japanese employees: The Furukawa nutrition and health study

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