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)

A statistically significant decrease in the intensity of catecholamine fluorescence of some carotid body glomus cells was observed after inhibition of the enzyme tyrosine hydroxylase by injection of 80 mg/kg alpha-methyl-paratyrosine. The intensity of the formaldehyde-induced fluorescence was measured in individual glomus cells. The maximum decrease in the intensity was observed 4 to 6 hr after the alpha-methyltyrosine injection. This suggests a rapid turnover in the catecholamines of the carotid body.
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PMID:Loss of histochemically demonstrable catecholamines in the glomus cells of the carotid body after alpha-methyl-para-tyrosine treatment. 1 34

Quantitative microfluorimetric studies were carried out on the formaldehyde induced fluorescence of dopamine in nerve terminals of the nuc. caudatus putamen using the technique of Falck and Hillarp. After tyrosine hydroxylase inhibition produced by alpha-methyl-p-tyrosine (H 44/68) a time-dependent disappearance of the dopamine fluorescence occurred in an exponential manner, T1/22.6 hr. Apomorphine treatment resulted in a considerable counteraction of the H 44/68 induced reduction of the fluorescence, whereas treatment with haloperidol potentiated it. Administration of gamma-hydroxybutyrolactone led to a marked increase of the dopamine fluorescene. The present microfluorimetric results were in perfect agreement with chemical-analytical determinations of dopamine carried out under identical experimental conditions, and with those reported previously. The fluorescence intensities obtained in the nuc. caudatus putamen were found to be in the linear part of the dopamine fluorescence concentration relationship as observed in protein models. It may be concluded that by using microfluorimetric quantitation of the formaldehyde induced fluorescence in the nuc. caudatus putamen it is possible to obtain a reliable quantitation of the relative amount of dopamine in the dopamine nerve terminals.
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PMID:Quantitative microfluorimetry of formaldehyde induced fluorescence of dopamine in the caudate nucleus. 23 82

This study investigates the role norepinephrine (NE) may play in regulating the differentiation of quail neural crest cells into sympatho-adrenal cells. Cues originating from the embryonic microenvironment are thought to play an important role during development. It is conceivable that NE has a positive regulatory function because adrenergic expression by quail neural crest cells in clonal culture can be inhibited by NE uptake inhibitors such as desipramine (DMI). This possibility is further supported by the notion that in the avian embryo presumptive adrenergic neural crest cells are likely to encounter catecholamines shortly after they have acquired the NE uptake mechanism. Our present data indicate that neural crest cells in clonal culture express a high affinity NE uptake system that can be inhibited by desipramine. As in the embryo, it appears before noticeable levels of catecholamines are accumulated by neural crest cells, as judged by formaldehyde-induced catecholamine fluorescence (FIF). A comparison of the time course of appearance of different adrenergic markers suggests that immunoreactivity against the biosynthetic enzyme tyrosine hydroxylase (TH) may appear first, and that it is followed very closely by the appearance of detectable levels of dopamine-beta-hydroxylase (DBH) and the NE uptake mechanism. Accumulation of catecholamines (FIF) is observed last. Addition of exogenous NE leads to an increase in adrenergic expression in vitro as judged by an increase in the number of colonies containing FIF-positive cells as well as cells expressing the biosynthetic enzymes TH and DBH. This suggests that exogenous NE can play a positive regulatory role in the differentiation of quail neural crest cells into sympathoadrenal cells.
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PMID:Characterization of the norepinephrine uptake system and the role of norepinephrine in the expression of the adrenergic phenotype by quail neural crest cells in clonal culture. 161 15

Sympathetic ganglion tissue of young (3 months) and aged (24 months) NMRI mice was allotransplanted into the submandibular gland to study the influence of aging on the survival of grafted neurons. The submandibular gland (SMG) was chosen as a host tissue because of its high concentration of NGF and good blood supply. Four weeks postgrafting the viability of transplants was evaluated using the formaldehyde-induced fluorescence technique, tyrosine hydroxylase (TH) immunohistochemistry, and morphometry. The density of neurons, catecholamine fluorescence and TH immunoreactivity (TH-IR) appeared to be almost unchanged when the transplant was completely surrounded by the SMG tissue, whereas transplants located within the interlobular septum and capsule, or even outside the capsule, showed significantly reduced neuronal survival. The shape of most of the transplanted neurons was not different from those in the intact ganglia. The average diameter of the transplanted young neurons was significantly decreased; this was not the case with the aged neurons. The histograms of grouped diameter values showed a shift to smaller cells in ganglion transplants in both age groups. The transplants in mice treated with 6-OH-dopamine showed considerable regrowth of adrenergic nerve fibers. There seemed to be no marked difference in the survival of transplanted neurons between aged and young animals. The results indicate that the sympathetic neurons from both young adult and aged animals survive the allotransplantation procedure. The neurotrophic factors together with dense vascularization present in the mouse submandibular gland may be beneficial for the restoration of the integrity of mature and aged adrenergic neurons.
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PMID:Histochemistry of sympathetic neurons allotransplanted from young and aged mice to the submandibular gland. 167 51

This study was undertaken to determine whether immuno-histochemical staining for DOPA decarboxylase (DDC) is present in axons of rat noradrenergic sympathetic neurons. A sparse plexus of varicose axons exhibiting DDC-like immunoreactivity (DDC-IR) was associated with blood vessels and acini in the submandibular gland, but this was much less extensive than the population that exhibited tyrosine hydroxylase-like immunoreactivity (TH-IR). The varicose terminal TH-IR axons in atrium, spleen, and vas deferens were devoid of DDC-IR both in grown rats and during the post-natal period of axon growth, although weak DDC-IR was seen in large pre-terminal nerve bundles. Similar patterns of staining were seen with paraffin-embedded and with frozen, formaldehyde-fixed material. No enhancement of DDC-IR was seen in any tissue after chronic alteration of catecholamine turnover with reserpine or alpha-methyl-para-tyrosine, and the numbers of submandibular DDC-IR axons were not increased by disruption of axonal transport with colchicine or by decentralization of the superior cervical ganglion. We conclude that terminal noradrenergic axons contain insufficient DDC-IR for microscopic visualization, regardless of their metabolic state, reinforcing previous evidence that DDC-IR can be used as a histochemical marker for dopaminergic axons. By this criterion, the rat submandibular gland may receive a sparse dopaminergic innervation.
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PMID:Neuronal metabolism and DOPA decarboxylase immunoreactivity in terminal noradrenergic sympathetic axons of rat. 167 38

The data in the preceding paper [Halliday G. M. and McLachlan E. M. (1991) Neuroscience 43, 531-550] suggest that some neurons in the rostral ventrolateral medulla contain some catecholamine-synthesizing enzymes but may not produce catecholamines. The present study addresses this question directly by comparing the anatomical location and morphology of these neurons with those revealed by formaldehyde-induced fluorescence. Catecholamine-containing somata of rats and guinea-pigs have been demonstrated following FAGLU-perfusion in normal untreated animals, in animals pretreated with pargyline (a monoamine oxidase inhibitor), and in animals pretreated with colchicine (to block axoplasmic transport). The number and location of fluorescent somata in the ventrolateral medulla have been determined in serial coronal sections of tissue from the cervical spinal cord to the level of the facial nucleus. Catecholamine-fluorescent neurons at different levels of the ventrolateral medulla varied in their topography and sensitivity to pharmacological manipulation. However, the rostrocaudal distributions in rats and guinea-pigs were quantitatively remarkably similar implying that homologous groups of catecholamine-containing neurons exist. Comparison between these distributions and those of somata stained immunohistochemically for catecholamine-synthesizing enzymes and neuropeptide Y [Halliday G. M. and McLachlan E. M. (1991) Neuroscience 43, 531-550] revealed that the majority of fluorescent neurons in both species probably contain dopamine-beta-hydroxylase and neuropeptide Y as well as tyrosine hydroxylase. Those neurons lying just caudal to the facial nucleus immunoreactive for tyrosine hydroxylase and phenylethanolamine-N-methyltransferase but not dopamine-beta-hydroxylase and neuropeptide Y also lack catecholamine fluorescence. This rostral group of somata can be identified immunohistochemically in cats. The size and morphology of catecholamine-fluorescent neurons have been analysed in detail, and compared with the same features of the immunohistochemically stained neurons. Three morphological types of catecholamine-containing neurons could be distinguished in material prepared by both techniques from rats and guinea-pigs, and in immunohistochemical material from cats. Rostral tyrosine hydroxylase-positive neurons, which differed morphologically from these three types, were present in all three species. On the basis of anatomical location, neuronal morphology and chemical characteristics, four groups of tyrosine hydroxylase-immunoreactive neurons have been identified in the ventrolateral medulla of rats, guinea-pigs and cats. Only the caudal three of these four groups appear to synthesize catecholamine, probably noradrenaline. From published data it seems likely that these four groups of tyrosine hydroxylase-positive neurons have distinct projections and functions related to cardiovascular and respiratory control.
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PMID:Four groups of tyrosine hydroxylase-immunoreactive neurons in the ventrolateral medulla of rats, guinea-pigs and cats identified on the basis of chemistry, topography and morphology. 168 68

Incubation of turtle or Xenopus retinas in 0.1 nM [125I]SCH 23982, a dopamine D1 receptor antagonist for 30-45 min and subsequent fixation in paraformaldehyde/glutaraldehyde resulted in strong blue formaldehyde-induced fluorescence of inner retinal neurons. On the basis of their morphological features, the labeled cells were classified as dopaminergic cells, an identification which was confirmed by double-labeling experiments using an antiserum against tyrosine hydroxylase. The whole experiment can be conducted in less than 2 h (whole mount), the label is very stable and allows the use of high-magnification objectives for detailed morphological investigation of dopaminergic retinal neurons.
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PMID:[125I]SCH 23982, a new tool for rapid visualization of dopaminergic neurons in lower vertebrate retinas. 170 84

Adrenal medullary tissue was autotransplanted to the superior cervical ganglion (SCG) of aged (26 months old) and young adult (3 months old) rats. Four and 20 weeks after operation, the viability of the transplants was evaluated using the formaldehyde-induced fluorescence (FIF) technique and tyrosine hydroxylase (TH) immunocytochemistry. Four weeks postgrafting, the transplant consisted of a densely-packed group of intensively fluorescent chromaffin cells in both age groups. The cells showed strong TH immunoreactivity and some of them were elongated, but only a few displayed short processes. At 20 weeks, most of the cells were spindle shaped and sent out fluorescent processes and a few of them were transformed toward ganglion-like cells. The results suggest that both young and old adrenal chromaffin cells are able to survive, produce neuronal processes and transform toward a neuronal phenotype in the rat superior cervical ganglion.
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PMID:Viability of adrenal chromaffin cells in the superior cervical ganglion of young adult and aged rats. 227 73

We studied the distribution, within the rabbit medulla oblongata, of neuronal cell bodies containing either tyrosine hydroxylase or neuropeptide Y-like immunoreactivity. Both avidin-biotin and immunofluorescence procedures were used. Because the two primary antibodies were raised in different species it was possible to perform simultaneous colocalization studies with the immunofluorescence procedure. Tyrosine hydroxylase-containing neurons in the rostral medulla were demonstrated to contain a catecholamine by the colchicine-enhanced FAGLU (formaldehyde-glutaraldehyde) fluorescence histochemical procedure. These neurons are presumably adrenergic, corresponding to the C1 and C2 groups described in the rat. No C3 group was found in the rabbit. The distribution of tyrosine hydroxylase-containing neurons in the caudal medulla was in accordance with previous descriptions of the A1 and A2 groups based on the unenhanced FAGLU procedure. Neuropeptide Y-like immunoreactivity was observed in cell groups corresponding to those already described in the rat, but additional groups were discovered in the rabbit. Some neurons containing neuropeptide Y-like immunoreactivity were observed in nucleus raphe pallidus and these also contained serotonin (5-HT). In the nearby nucleus reticularis gigantocellularis there were occasional neurons that contained neuropeptide Y-like immunoreactivity without any colocalized 5-HT. Neuropeptide Y-like immunoreactivity was also observed in the dorsal motor nucleus of the vagus, rostral to the obex, and these neurons were demonstrated to be true vagal preganglionic cells by colocalization of neuropeptide Y-like immunoreactivity and Fast Blue retrogradely transported from the cervical vagus. We found that neuropeptide Y-like immunoreactivity was colocalized in approximately 75% of the tyrosine hydroxylase-containing neurons in the rostral medulla (C1 and C2 cells). A smaller proportion of the A1 cells also contained this peptide but it was absent from both the most caudal A1 cells and from the A2 cells. Some tyrosine hydroxylase-containing neurons occur in direct apposition to vagal preganglionic cells in both the dorsal motor nucleus of the vagus and the nucleus ambiguous. However, colocalization studies revealed that none of these neurons contained Fast Blue when this dye was retrogradely transported from the cervical vagus. Medullary catecholamine-synthesizing neurons apparently do not contribute axons to the vagus nerve. This finding is consistent with our own studies in the rat but is in contrast to studies in this species published by other workers.
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PMID:Distribution of tyrosine hydroxylase and neuropeptide Y-like immunoreactive neurons in rabbit medulla oblongata, with attention to colocalization studies, presumptive adrenaline-synthesizing perikarya, and vagal preganglionic cells. 242 47

The C1 cell group in the rat is characterized by neurones which contain both adrenaline and phenylethanolamine-N-methyltransferase, and usually also neuropeptide Y (NPY). The former two substances are lacking in Guinea pig brainstem and spinal cord. We have examined the distribution of NPY- and tyrosine hydroxylase-immunoreactivity in the ventrolateral medulla and thoracolumbar intermediate zone of Guinea pig, as well as the distribution of catecholamine-containing neurone somata and spinal terminals visualized after formaldehyde-glutaraldehyde fixation. The results are compared with comparable immunohistochemical data obtained from rats and rabbits. Catecholaminergic neurones in the Guinea pig with locations and terminations that correspond to those of the C1 cell group in rat and its analogue in the rabbit appear to consist of two subgroups, with only the more caudal group containing NPY. The more rostral group requires pretreatment with monoamine oxidase inhibitor to permit visualization of catecholamine fluorescence, a property previously though to be characteristic of adrenergic neurones. This observation raises the possibility that the catecholaminergic cell group in the C1 region of rabbits may not contain adrenaline either.
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PMID:Are there bulbospinal catecholaminergic neurones in the guinea pig equivalent to the C1 cell group in the rat and rabbit? 256 56


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