Tyrosine Hydroxylase: Activation by Nerve Stimulation

Morgenroth, Victor H.; Boadle-Biber, Margaret C.; Roth, Robert H.

doi:10.1073/pnas.71.11.4283

Cited by 81 publications

(29 citation statements)

References 16 publications

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“…Progesterone did not alter the K m and V max of hypothalamic TH for tyrosine but that for the cofactor was altered (K m increased, V max decreased; Beattie & Soyka 1973). However, Morgenroth et al (1974) have reported changes in the K m and V max for substrate as well. In the catfish, we have reported changes in apparent K m values for both substrate and cofactor across the seasons, sexes and brain regions (Chaube & Joy 2002a,b).…”

Section: Discussionmentioning

confidence: 99%

Effects of ovariectomy and oestradiol-17beta replacement on brain tyrosine hydroxylase in the catfish Heteropneustes fossilis: changes in in vivo activity and kinetic parameters

Chaube

Joy²

2002

Journal of Endocrinology

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In Heteropneustes fossilis, ovariectomy inhibited in vivo brain (hypothalamus-pituitary, telencephalon and medulla oblongata) tyrosine hydroxylase (TH) activity with significant effects in weeks 2, 3, 4 and 5 of the gonadal resting phase and in weeks 3, 4 and 5 of the prespawning phase (P<0·05, Tukey's test). Oestradiol-17 (OE 2 ) replacement in 3-week ovariectomised fish produced biphasic responses in both seasons; the low dosages of 0·05 and 0·5 µg/g body weight (BW) elevated TH activity, whereas the high dosages of 1·0 and 2·0 µg/g BW decreased it. The magnitude of the inhibition was higher in the resting phase than in the prespawning phase. The inhibitory effect of ovariectomy may be produced by elevating the apparent K m values (decreased affinity) of the enzyme for both -tyrosine (substrate) and dimethyltetrahydropteridine (cofactor) and consequently decreasing the V max . Significant changes (P<0·05) in both these parameters were noticed but showed minor differences with regard to the length of ovariectomy, season or brain regions. The biphasic effects of OE 2 replacement on TH activity seemed to be produced by differential effects on apparent K m and V max . The stimulatory effect of the low dosages of OE 2 coincides with a decrease in the apparent K m values (increased affinity) for both substrate and cofactor and an increase in the V max of the enzyme. The inhibitory effect of the high dosages of OE 2 correlated with an increase in the apparent K m values (decreased affinity) for both substrate and cofactor, and a decrease in the V max compared with the lower dosage groups. The results strongly suggested that OE 2 can modulate brain catecholaminergic activity at the level of tyrosine hydroxylation which, in turn, may alter gonadotrophin secretion. OE 2 may elicit biphasic effects by differentially altering the enzyme affinity towards the substrate and cofactor.

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Section: Discussionmentioning

confidence: 99%

Effects of ovariectomy and oestradiol-17beta replacement on brain tyrosine hydroxylase in the catfish Heteropneustes fossilis: changes in in vivo activity and kinetic parameters

Chaube

Joy²

2002

Journal of Endocrinology

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“…Eceleston~ et al, 1970, Morgenroth et al 1974. Because increased electrical activity results in an increased flux of calcium ion into the synaptic terminals, calcium-dependent phosphorylation resulting in activation of the transmitter synthesizing enzymes provides a plausible, direct mechanism for this stimldation.…”

Section: Regulation Of Synthesis Of the Biogenic Aminesmentioning

confidence: 99%

Experimental Approaches to Understanding the Role of Protein Phosphorylation in the Regulation of Neuronal Function

Kennedy¹

1983

Annu. Rev. Neurosci.

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“…These results were interpreted as suggesting that the increased synthesis of catecholamines from tyrosine associated with acute nerve stimulation is not simply the consequence of reduced end-product feedback inhibition secondary to the release of catecholamines, and that other effects may also contribute, including perhaps the production of a positive allosteric effector during nerve stimulation, which increases the tyrosine hydroxylase activity (33). More recent experiments have also demonstrated that electrical stimulation of the guinea pig hypogastric nerve-vas deferens preparation (27) as well as of locus coeruleus-hippocampal noradrenergic (34), and of nigro-striatal dopaminergic (35) neurons in the rat brain causes an activation of soluble tyrosine hydroxylase. These instances of increased activity of neuronal tyrosine hydroxylase following nerve stimulation, at least in brain tissue (34,35), and possibly (27), though not necessarily (33), in the vas deferens, appear to be mediated by an increased affinity of tyrosine hydroxylase for both substrate and cofactor and a decreased affinity for inhibitory end-products.…”

mentioning

confidence: 99%

“…More recent experiments have also demonstrated that electrical stimulation of the guinea pig hypogastric nerve-vas deferens preparation (27) as well as of locus coeruleus-hippocampal noradrenergic (34), and of nigro-striatal dopaminergic (35) neurons in the rat brain causes an activation of soluble tyrosine hydroxylase. These instances of increased activity of neuronal tyrosine hydroxylase following nerve stimulation, at least in brain tissue (34,35), and possibly (27), though not necessarily (33), in the vas deferens, appear to be mediated by an increased affinity of tyrosine hydroxylase for both substrate and cofactor and a decreased affinity for inhibitory end-products. These results are similar to the effects we observed with cAMP (Table 3, Figs.…”

mentioning

confidence: 99%

“…Soluble tyrosine hydroxylase activity was assayed in a 100,000 X g supernatant extract of striatal tissues homogenized in 50 mM Tris-acetate buffer, pH 6.0, by a modification of the method of Shiman et al (25) described elsewhere in detail (17,26,27). The soluble extracts (50-70 Ag of protein) 'were preincubated for 5 min and incubated after addition of substrate for 45 min in 1.0 ml of medium containing partially purified sheep liver pteridine reductase (70 Ag of protein-a 10-fold excess over the amount required for maximal tyrosine hydroxylase activity), NADPH (1 mM), catalase (3300 units), sodium acetate buffer, pH 6.0 (50 mM), and various concentrations of Me2PtnH4 or tetrahydrobiopterin (bPtnH4, donated by Roche Products, Ltd. of England) and i- [3,5-3H ]tyrosine.…”

mentioning

confidence: 99%

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Activation by cyclic 3':5'-adenosine monophosphate of tyrosine hydroxylase in the rat brain.

Harris¹,

Baldessarini²,

Morgenroth³

et al. 1975

Proc. Natl. Acad. Sci. U.S.A.

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Membrane-permeable derivatives of cyclic AMP (cAMP) produced concentration-dependent increases in activity of tyrosine hydroxylase [L-tyrosine, tetrahydro-pteridine: oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.21 in membrane-limited nerve endings (synaptosomes) prepared from three regions of rat brain. Increased hydroxylation occurred even after preincubation and removal of dibutyryl cyclic AMP. In all brain regions, the hydroxylation of phenylalanine and tyrosine was increased, but dibutyryl cAMP had little effect on activity of tryptophan hydroxylase, no effect on aromatic amino-acid decarboxylase, on uptake of tyrosine or phenylalanine, uptake or efflux of dopamine, or distribution of hydroxylase between cytoplasmic and particulate components of the synaptosomes. Dibutyryl cAMP decreased inhibition of catecholamine synthesis in synaptosomes by dopamine and apomorphine. In a soluble preparation of striatal tyrosine hydroxylase, activity was increased by addition of lower concentrations of cAMP or dibutyryl cAMP than with unbroken nerve endings, when subsaturating concentrations of tyrosine and cofactor were employed, while butyrate, chloride, 5'-AMP, ADP, ATP, and cyclic GMP had no activating effect, Increased activity of soluble tyrosine hydroxylase was reflected in increased affinity (Kin) for substrate and cofactor and decreased affinity (KJ) for inhibitory end-product (dopamine), suggesting a change in the physical-chemical state of the enzyme or an activator molecule. Cyclic AMP may activate tyrosine hydroxylase during periods of increased neuronal activity.Some effects of dopamine and norepinephrine as neurotransmitters may be mediated by their activation of adenylate cyclase to increase cellular concentrations of cyclic 3': 5'-adenosine monophosphate (cyclic AMP). Catecholamines stimulate the production of cyclic AMP in the pineal gland (1), superior cervical ganglion (2), retina (3), and in slices (4, 5) or homogenates (6, 7) of portions of the brain. Neurophysiological depressant effects of catecholamines on neurons of brain (8,9) and sympathetic ganglia (10) can be mimicked by exogenous cyclic AMP. Thus, cyclic AMP may act postsynaptically in mediating adrenergic neurotransmission. Dibutyryl cyclic AMP stimulates release of norepinephrine from the hypogastric nerve-vas deferens preparation (11) and adrenal medulla (12). Moreover, injections of dibutyryl Abbreviations: cAMP, cyclic 3': 5'-adenosine monophosphate; BtecAMP, dibutyryl cyclic AMP; pterin, 2-amino4-hydroxypteridine; bPtnH4, tetrahydrobiopterin; Me2PtnH4,6,6,7, (190-210 g) were homogenized in isotonic sucrose under conditions that preserve the integrity of synaptosomes, and the 1000 X g supernatant material was either assayed directly or the crude 17,000 X g mitochondrial-synaptosomal pellet (P2) was used (19)(20)(21)(22)(23). Synaptosomal preparations were incubated in a Krebs-Ringer phosphate medium buffered at pH 6.7, the optimum for this assay in synaptosomes, as described previously (20)(21)(22)

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Tyrosine Hydroxylase: Activation by Nerve Stimulation

Cited by 81 publications

References 16 publications

Effects of ovariectomy and oestradiol-17beta replacement on brain tyrosine hydroxylase in the catfish Heteropneustes fossilis: changes in in vivo activity and kinetic parameters

Effects of ovariectomy and oestradiol-17beta replacement on brain tyrosine hydroxylase in the catfish Heteropneustes fossilis: changes in in vivo activity and kinetic parameters

Experimental Approaches to Understanding the Role of Protein Phosphorylation in the Regulation of Neuronal Function

Activation by cyclic 3':5'-adenosine monophosphate of tyrosine hydroxylase in the rat brain.

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