Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.14.16.2 (tyrosine hydroxylase)
 14,760 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of chlorpromazine and of some metabolites of chlorpromazine on the apomorphine-elicited inhibition of synaptosomal tyrosine hydroxylase activity were investigated. Chlorpromazine, nor1-chlorpromazine and 7-hydroxychlorpromazine reverse the apomorphine-elicited inhibition of tyrosine hydroxylase activity while nor1-chlorpromazine sulfoxide and nor2-chlorpromazine sulfoxide have no effect on this inhibition. 6-Hydroxychlorpromazine and promethazine also reverse the enzyme inhibition by apomorphine but are less potent than chlorpromazine or 7-hydroxychlorpromazine. These results show that chlorpromazine and its metabolites with antipsychotic activity are more effective in reversing the apomorphine-elicited inhibition of tyrosine hydroxylase than those metabolites which are devoid of antipsychotic activity.
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PMID:The effect of various chlorpromazine derivatives on the apomorphine-elicited inhibition of synaptosomal tyrosine hydroxylase activity. 0 59

The effects of surgical transection of the postganglionic nerve trunk of the superior cervical ganglion on the total protein content and levels of the enzymes tyrosine hydroxylase, DOPA decarboxylase and choline acetyltransferase have been studied in the adult rat. There is a minor decrease in the total activities of these 3 enzymes accompanied by a large increase in the total protein content of the ganglion. The trans-synaptic induction of the enzyme tyrosine hydroxylase by reserpine is not affected by postganglionic axotomy. Increased activity mediated by reserpine caused no change in the total activities of either DOPA decarboxylase or choline acetyltransferase. Previously observed effects of postganglionic axotomy on preventing transmission through the ganglion are compared with these results and the possible mechanisms by which trans-synaptic induction may occur are discussed.
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PMID:Effects of axotomy on the trans-synaptic regulation of enzyme activity in adult rat superior cervical ganglia. 0 75

Discrete brain areas and sympathetic ganglia obtained at autopsy from patients with idiopathic orthostatic hypotension were assayed for tyrosine hydroxylase and dopamine beta-hydroxylase. Dopamine beta-hydroxylase activity was decreased 7.5-fold in sympathetic ganglia, while tyrosine hydroxylase activity was reduced more than 50-fold in the pontine nucleus locus coeruleus. These observations indicate that noradrenergic neurons of both brain and ganglion are affected in idiopathic orthostatic hypotension, but suggest that the central and peripheral biochemical deficits differ.
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PMID:Catecholamine enzymes in the degenerative neurological disease idiopathic orthostatic hypotension. 0 74

Time-course variations in tyrosine hydroxylase activity were measured in the locus coeruleus of the albino rat after electrolytic coagulation of either the nucleus raphe dorsalis or the nucleus raphe centralis. Highly significant increases were measured at 4 days after lesioning of the raphe dorsalis (30.33%) and the raphe centralis (81.55%) compared with control values, whereas the activity in groups A9 and A10 was unchanged at this time-point. In conjunction with other experimental evidences, an hypothesis is proposed that the catecholaminergic neurons located in the locus coeruleus are directly and/or indirectly controlled by the serotonin-containing neurons located in the anterior raphe system nuclei.
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PMID:Time-course variations in tyrosine hydroxylase activity in the rat locus coeruleus after electrolytic destruction of the nuclei raphe dorsalis or raphe centralis. 0 15

Dibutyryl cyclic AMP (dB-cAMP) elicits a concentration-dependent stimulation of tyrosine hydroxylase activity in the striatal and mesolimbic synaptosomes. The per cent of stimulation is significantly higher in the mesolimbic synaptosomes than in the striatal synaptosomes. dB-cAMP and depolarizing agents (ouabain or veratridine) have an additive effect on synaptosomal tyrosine hydroxylase activity, indicating that they stimulate tyrosine hydroxylase activity by different mechanisms. cAMP does not stimulate soluble striatal tyrosine hydroxylase activity unless it is added in combination with ATP and Mg2+, compounds required for the activity of cAMP-dependent protein kinase. The cAMP elicited per cent stimulation of soluble tyrosine hydroxylase activity is dependent upon the concentration of added protein kinase and upon the pH of the reaction. dB-cAMP has the same effect on the kinetic state of tyrosine hydroxylase in synaptosomes as cAMP on the soluble tyrosine hydroxylase. The nucleotide does not alter the apparent Km for tyrosine, reduces the Km for the pteridine cofactor and increases the Ki for dopamine. Thus, cAMP increases the affinity of tyrosine hydroxylase for the pteridine cofactor and concomitantly decreases the affinity for the end-product inhibition.
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PMID:Stimulation of tyrosine hydroxylase activity by cyclic AMP in synaptosomes and in soluble striatal enzyme preparations. 0 24

Activities of choline acetyltransferase (ChAC), glutamate decarboxylase (GAD) and tyrosine hydroxylase (TH), enzymes catalyzing the synthesis of acetylcholine (ACh), gamma-aminobutyric acid (GABA) and catecholamines, respectively, were measured in the cochlea and cochlear nucleus of the guinea pig. ChAc activity in the organ of Corti, third turn, was 1270 pmole ACh formed/min/mg protein (ChAc, 1270) and was higher than in turn 4 (ChAc, 543). ChAc activity was higher when the preparation included the inner hair cell region than when not. GAD activity in samples of turn 3 and 4 combined was low, 0.17 nmole GABA formed/min/mg protein (GAD, 0.17). All 3 enzymes were low in auditory nerve: ChAc, 1.7, GAD, 0.10 and TH, 1.0 pmole DOPA formed/min/mg protein. In the cochlear nucleus, the values were: ChAc, 129, GAD, 1.70 and TH, 2.7. The findings on the distribution of ChAc activity in the organ of Corti fit the hypothesis that the olivocochlear nerve fibers are cholinergic. Because of low GAD in the cochlea, GABA is unlikely to be transmitter in the organ of Corti. Similarly, it is unlikely that ACh, GABA or a catecholamine is a transmitter between the auditory nerve and the cochlear nucleus.
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PMID:Choline acetyltransferase, glutamate decarboxylase and tyrosine hydroxylase in the cochlea and cochlear nucleus of the guinea pig. 0 25

Pineal denervation by superior cervical ganglionectomy (Gx) decreased high affinity binding of estradiol (E2) to the pineal cytosol of female rats and of testosterone to the cytosol of male rats by 40 and 26% and by 75 and 80%, 5 and 14 days after sugery; hormone binding remained unchanged up to 24 h after surgery. Binding to the nuclear fraction decreased sigificantly by 2 weeks after incorporation of (3H) leucine into pineal proteins in Gx. A single injection of E2 (mug) to testosterone propionate (TP) (500 mug) failed to increase the Gx rats when injected 1 or 5 days after surgery. Significant increases were observed in sham-operated controls or in rats subjected to bilateral decentralization of ganglia; however on the 5th day an impairment was observed in hormone ability to enhance [3H]leucine incorporation in decentralized rats. The administration of isoproterenol 19 and 3 h before sacrifice replenished pineal-binding sites for E2 and testosterone in Gx rats, but failed to restore the responsiveness of denervated pineals to hormone administration. Moreover, E2 or TP treatment blocked the increase in labeled amino acid incorporation into proteins brought about by isoproterenol per se. The administration of propranolol 2 and 7 h after hormone injection decreased the ability of E2 and TP to enhance [3H]leucine incorporation by 55 and 41%, respectively. Tyrosine hydroxylase activity of the superior cervical ganglia decreased by 36 and 41% 6 h after E2 or TP administration, and by 43 and 47% after 3 daily injections of the hormones, whereas pineal tyrosine hydroxylase remained unchanged. Hormone treatment for 3 days increased the in vitro uptake of norepinephrine by the ganglia but did not affect uptake in the pineal gland. These data indicate that the integrity of neurons of the superior cervical ganglia is an absolute requirement for E2 and testosterone to enhance [3H]leucine incorporation into pineal proteins in rats.
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PMID:Changes in (3H)leucine incorporation into pineal proteins following estradiol or testosterone administration: involvement of the sympathetic superior cervical ganglion. 0 60

With the microdissection method of Palkovits, individual hypothalamic nuclei were removed from the brains of adult male rats, and the tyrosine hydroxylase (TH) activity of each nucleus was determined 7 days after gonadectomy or thyroidectomy. Following gonadectomy, TH activity increased significantly in the median eminence with no change in the periventricular (NPV), arcuate (NARC), and dorsomedial nuclei (NDM), or medial forebrain bundle (MF). Following thyroidectomy, TH activity increased significantly in all 5 hypothalamic nuclei examined. Placement of bilateral lesions in the ventral norepinephrine bundles resulted in a greater than an 85% fall in the dopamine-beta-hydroxylase activity of the median eminence, arcuate nucleus, and ventromedial nucleus, but had no effect on tyrosine hydroxylase activity measured in those same areas. Furthermore, placement of such lesions had no effect on the endocrine-induced increases of TH activity found in the median eminence following gonadectomy and thyroidectomy, but did prevent the increase of TH activity found in the NPV, NDM, and MFB following thyroidectomy. Three conclusions appear to be justified: (a) noradrenergic axons which innervate the median eminence, arcuate, and ventromedial nuclei course in the ventral norepinephrine bundles; (b) the TH content of noradrenergic neurons in the median eminence, arcuate nucleus, and ventromedial nuclei is quite small; and (c) the majority, if not all, of the endocrine-responsive catecholaminergic neurons in the median eminence are dopaminergic.
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PMID:The effect of bilateral lesions of the ventral noradrenergic bundle on endocrine-induced changes of tyrosine hydroxylase in the rat median eminence. 0 61

In previous reports, methamphetamine was shown to depress tyrosine hydroxylase (TH) activity in the rat corpus striatum. To evaluate further the mechanism of this decrease in TH activity, enzyme activity was measured in the rat corpus striatum and substantia nigra after repetitive and single-dose methamphetamine administration. Following repeated doses of methamphetamine, nigral TH activity decreased and reached 45% of controls at 12 hr and returned to normal at 60 hr. Striatal TH activity decreased to 40% of control at 36 hr and returned toward normal at 60 hr. When methamphetamine was administered every 6 hr for 30 hr and then discontinued, nigral TH activity returned toward control levels 4 days prior to recovery of striatal TH activity. Methamphetamine initially increased striatal dopamine levels at 6 hr (170% of control). Dopamine levels then decreased in parallel with striatal TH activity but failed to increase as the enzyme recovered. Concurrent administration of chlorpromazine with methamphetamine prevented the methamphetamine-induced decrease in nigral and striatal TH activity and striatal dopamine levels. The results indicate that the methamphetamine-induced depression of striatal and nigral TH activity may be related to increased stimulation of dopamine receptors in the striatum.
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PMID:Influence of methamphetamine on nigral and striatal tyrosine hydroxylase activity and on striatal dopamine levels. 0 86

The administration of guanethidine to newborn rats has been shown to produce a permanent sympathectomy with potential advantages over immunosympathectomy and 6-hydroxydopamine-induced chemical sympathectomy. In this paper, we report on a revised treatment regimen involving initiation of treatment (50 mg/kg/day) on day 7 after birth and continuing for 3 weeks. Animals treated by this protocol have a low mortality rate (approx. 10% above saline-treated controls) and no permanent growth deficit. Analysis of tyrosine hydroxylase activity in and light microscopic examination of superior cervical ganglia of the guanethidine-treated animals indicate complete destruction of sympathetic neurons by the end of the second week of treatment. During and after treatment there are no decreases in norepinephrine in whole brain of the treated animals. Norepinephrine levels in peripheral tissues are markedly reduced at both 9 and 16 weeks of age. Stimulation of vasomotor outflow produces no increase in blood pressure in guanethidine-treated rats at 9 or 26 weeks of age, indicating a complete and permanent functional denervation of the vasculature. The adrenal glands of the guanethidine-treated animals are not destroyed, but rather respond, apparently by transsynaptic induction, with increases in tyrosine hydroxylase and epinephrine content. Interestingly, despite the continued deprivation of a peripheral sympathetic nervous system in these animals. adrenal tyrosine hydroxylase and epinephrine levels return to control levels by 10 weeks of age. These data indicate that administration of guanethidine to newborn rats produces a very complete and permanent sympathectomy with significant advantages over immunosympathectomy and 6-hydroxydopamine-induced chemical sympathectomy.
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PMID:Modification and characterization of the permanent sympathectomy produced by the administration of guanethidine to newborn rats. 0 91


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