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)

In this study chromatographic, immunochemical, and immunocytochemical methods provide evidence of a galanin-like peptide(s) in an invertebrate, the blowfly Phormia terraenovae. The major portion of the galanin-like immunoreactivity (GAL-LI) in fly heads was extractable in acetic acid but not in boiling water, which suggests that the peptide(s) may be highly basic in nature. GAL-LI was present both in the head and body portion of the blowfly in roughly the same amounts. Initial gel filtration data, using a G-50 Sephadex column and a weak phosphate-buffer (pH 6.5) as eluent, suggested that a fly GAL-LI peptide(s) from fly heads, eluting as an apparent single peak, was smaller than porcine GAL(1-29) and GAL(1-15). However, concomitant analysis using a G-25 Sephadex column and acetic acid (0.2 M) as eluent, spread the immunoreactive material over a great portion of the chromatogram, although the main portion of the material eluted in the same size range as porcine GAL(1-29). Taken together, the gel filtration data thus suggest that fly GAL-LI peptide(s) may be highly basic but presumably similar in size to vertebrate GAL(1-29). However, the hydrophobic properties of the fly GAL-LI peptide(s) differ from that of porcine GAL as demonstrated by the presence of several immunoreactive components eluting both early as well as late in the chromatogram when using reverse-phase high performance liquid chromatography (HPLC); early peaks may represent highly basic and/or possibly smaller GAL-immunoreactive peptide(s), whereas later peaks may represent less basic and possibly elongated forms. Immunocytochemistry indicated that GAL-LI was present in the nervous system of the blowfly. About 160 GAL-immunoreactive neurons were found in the brain and subesophageal ganglion, 26 in the fused thoracic ganglion and 30 in the fused abdominal ganglion. In the brain, GAL-immunoreactive fibers supply specific subdivisions of the central body, optic lobe, superior protocerebrum, and tritocerebrum as well as neuropil in the subesophageal ganglia. In the thoracico-abdominal ganglia, GAL-immunoreactive neuron processes are found inside synaptic neuropil as well as in the neural sheath of the ganglia and several of the dorsal nerve roots. Many of the GAL-immunoreactive neurons react also with an antiserum against porcine galanin message associated peptide, a peptide present in the preprogalanin protein. Immunocytochemical double-labeling indicated that some GAL-immunoreactive neurons also reacted with antisera against the molluscan peptides FMRFamide and SCPB, whereas no evidence could be found for colabeling with antisera against tyrosine hydroxylase, substance P and physalaemin.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Galanin immunoreactivity in the blowfly nervous system: localization and chromatographic analysis. 172 Jul 94

Expression of tyrosine hydroxylase (TH) in cultured cells of the ventral hypothalamus-midbrain of fetal rats has been investigated. TH mRNA and TH were quantified by an S1 nuclease protection assay and an immunoblot assay, respectively. Dihydroxyphenylalanine (DOPA) and dopamine secretion were evaluated using their rates of accumulation in the culture medium. The rate of accumulation of DOPA was 2-3 times that of dopamine. Inhibitors of TH activity caused a dose-dependent reduction in DOPA secretion. During an 11-week culture of dissociated cells, TH mRNA increased from 1.6 to 2.8 attomole/well between the first and fourth week of culture, remained steady to the ninth week, and then declined. TH increased from 12 to 105 fmol/well between the first and seventh week and then declined. DOPA secretion increased until the sixth week and then remained steady to the tenth week. An extract of rat pituitaries stimulated DOPA secretion by the cultures in a dose-dependent manner. This activity, attributed to a cytotropic factor (CTF), was inactivated by heating for 10 min in a boiling water bath, but was unaffected by trypsin digestion. Incubation with CTF for 24, 48, 72, and 96 h resulted in a day by day increase in the secretion of DOPA. After 96 h of culture with CTF, the amount per well of TH mRNA, but not TH, was significantly (P less than 0.01) greater than the control value. Pituitary CTF is probably not PRL, since rat PRL did not appreciably affect DOPA secretion or the amount of TH mRNA or TH in the cells. Withdrawal of CTF from CTF-stimulated cells resulted in a marked reduction in DOPA secretion as well as a decrease in TH mRNA. These results support the hypothesis that the pituitary gland contains a cytotropic factor that stimulates TH expression in fetal brain cells of the hypothalamus-midbrain.
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PMID:Expression of tyrosine hydroxylase in cultured brain cells: stimulation with an extractable pituitary cytotropic factor. 197 Feb 92

An indirect immunohistochemical method was used to visualize nerves immunoreactive for tyrosine hydroxylase (THI) and dopamine-beta-hydroxylase (DBHI) in kidney sections of cats 6 weeks and 2 and 3 months of age. THI and DBHI nerve terminals innervate the renal pelvis, interlobar veins and arterial tree including medullary vascular bundles of cats of each age studied. In kidneys of 6-week-old cats, THI and DBHI axons form elaborate plexuses that are distributed throughout much of the inner medulla, whereas some medullary axons appear to degenerate at 2 months and no inner medullary plexuses were visualized in 3-month-old cats. Transitory inner medullary nerves in the cat kidney may influence cellular development and play a role in salt and water balance.
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PMID:Transitory inner medullary nerve terminals in the cat kidney. 197 58

Norepinephrine metabolism was investigated in 6-wk-old male Swiss albino copper-deficient and copper-supplemented mice. Beginning 4 d after birth of pups, dams were fed a diet low in copper (Cu) (0.4 mg/kg) and offspring were weaned to this diet at 21 d of age. Half the dams and their respective offspring received Cu (20 micrograms/ml) in the drinking water (+Cu) and served as controls. Unsupplemented offspring (-Cu) had lower liver Cu levels, exhibited anemia, and had increased heart weights but normal body weights compared to +Cu mice. Urinary output of norepinephrine and dopamine was higher, whereas output of creatinine and epinephrine was not different in -Cu mice compared to +Cu mice. Both fractional and calculated turnover of norepinephrine following inhibition of tyrosine 3-monooxygenase by alpha-methyl-p-DL-tyrosine methyl ester (alpha-MT) was higher in hearts from -Cu mice than in those from +Cu mice. Hearts and spleens from -Cu mice appeared to have higher tyrosine 3-monooxygenase activity as judged by increasing rates of L-dihydroxyphenylalanine accumulation following injection of m-hydroxybenzylhydrazine (NSD-1015), an inhibitor of aromatic amino acid decarboxylase. Turnover rates of norepinephrine for cerebellum were not different between +Cu and -Cu mice. Loss of norepinephrine from adrenal glands of mice injected with alpha-MT was not observed in the 8-h period studied. The smaller norepinephrine pool observed in organs of -Cu mice may have resulted from lower synthesis due to limiting dopamine-beta-monooxygenase activity and to higher turnover.
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PMID:Copper-deficient mice have higher cardiac norepinephrine turnover. 230 15

Male rats were exposed to severe 14 day immobilization stress. Body weight, body temperature, food and water intake, behavioral parameters, and serum corticosterone levels were measured during and after the stress period. On the 7th day after cessation of stress the experimental animals together with the control rats were taken to immunocytochemical analysis involving morphometry and microdensitometry of tyrosine hydroxylase (TH), 5-hydroxytryptamine (5-HT), various neuropeptide, and glucocorticoid receptor (GR) immunoreactivities (IRs) in a large number of regions of the central nervous system. In addition, adrenocorticotropic hormone (ACTH) IR was analyzed in the pituitary gland. Seven days following cessation of the chronic stress food intake, total locomotion and forward locomotion had been restored to normal. Serum corticosterone levels appeared to remain increased even 6 days following cessation of the chronic immobilization stress, probably caused by increased release of ACTH. Paraventricular corticotropin releasing hormone (CRF) IR was negatively correlated with the pituitary ACTH IR, indicating that the increase in ACTH release was produced by an increased release of CRF from the hypothalamus. The major immunocytochemical change observed 7 days after cessation of stress was a disappearance of 5-HT IR in the 5-HT cell groups B1, B2, B3, and B7. 5-HT IR in nerve terminals was only affected in the dorsal horn, where 5-HT IR was increased in the substantia gelatinosa. GR IR was found to be significantly increased in monoaminergic cell groups: serotoninergic B7, dopaminergic A12, and noradrenergic A1, A2, and A6. A trend for a reduction of TH IR was observed in nigral DA cells associated with significant reductions in TH IR in striatal DA nerve terminals. Finally, increases in 5-HT and substance P (SP) IR were found in the nerve terminals of the substantia gelatinosa of the cervical spinal cord in the stress group. In the present experimental model evidence has been obtained for a maintained activation of the hypothalamic-pituitary-adrenal axis as evaluated 7 days after cessation of severe chronic immobilization stress. The reduction of 5-HT IR in various 5-HT cell groups indicates a reduction of 5-HT synthesis, which may also be associated with reduced 5-HT release from the nerve terminals, since no depletion was observed in terminal regions and in one case an increase in 5-HT IR was noted (substantia gelatinosa).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Chronic immobilization stress: evidence for decreases of 5-hydroxy-tryptamine immunoreactivity and for increases of glucocorticoid receptor immunoreactivity in various brain regions of the male rat. 276 Jun 6

The recently discovered cardiac peptides, called atrial natriuretic factors (ANF), act peripherally as hormones which control fluid and electrolyte homeostasis. Their renal, adrenal and vascular effects are complemented by central nervous system (CNS) actions to inhibit vasopressin secretion, salt preference, and water intake, and to inhibit the CNS component of the hypothalamo-pituitary-adrenal axis. These central actions of ANF are thought to mirror physiological roles played by endogenous, neuronally derived ANF within the brain. ANF immunoreactivity and binding sites in the anterior pituitary gland and median eminence suggest, as well, neuroendocrine actions of the peptide. We have failed to observe direct pituitary effects of ANF on basal or stimulated pituitary hormone secretion; however, specific hypothalamic actions have been discovered. ANF infusions (IV or cerebroventricular) inhibit luteinizing hormone (LH) secretion via, at least in part, an opioid mechanism since naloxone pretreatment blocks the effect. Additionally ANF inhibits catecholamine stimulation of the release of LH-releasing factor in the median eminence. Direct effects of ANF on tuberoinfundibular dopamine neurons are suggested by the observation that the prolactin-inhibiting action of ANF is prevented by domperidone treatment and is absent following alpha methyl-p-tyrosine inhibition of tyrosine hydroxylase activity. These recent results imply neuromodulatory actions of ANF within the CNS that are expressed via interaction with brain peptide and catecholamine systems.
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PMID:Central nervous system actions of atrial natriuretic factor. 284 6

The effects of lead, a known neurotoxin on the metabolism of a vital tetrahydrobiopterin cofactor for the hydroxylation enzymes tyrosine hydroxylase, phenylalanine hydroxylase and tryptophan hydroxylase, have been investigated. Reduced availability of this pteridine has the potential to reduce the level of the neurotransmitters noradrenaline, adrenaline and 5-hydroxytryptophan in the brain. Using the rat as a model, increases in tetrahydrobiopterin concentration and in the activity of dihydropteridine reductase, an enzyme involved in tetrahydrobiopterin metabolism, were observed after exposure to lead via the drinking water. Possible explanations for this increased level of tetrahydrobiopterin relate to alterations in the balance between synthesis and salvage of this co-factor.
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PMID:Neurotoxic action of lead: effect on tetrahydrobiopterin metabolism in the rat. 286 Oct 54

In an attempt to produce an animal model of Parkinson's disease, we injected rats repeatedly with high doses of methylcyclopentadienyl manganese tricarbonyl (MMT), a compound which has been reported to lower striatal dopamine content in mice. Chronic MMT administration for up to 5 months, even though it produced a substantial elevation in brain manganese content during the period of exposure, did not destroy dopaminergic nigrostriatal neurons. This was assessed by measurements of tyrosine hydroxylase activity and contents of dopamine and its metabolites in the striatum, and by histological examination of the substantia nigra. Our results differ from those of others who administered manganese chloride in drinking water to rats. This discrepancy is unlikely to be a consequence of differences in duration of exposure or route of administration. It could be due to our having used an organic rather than an inorganic manganese compound, or to a species difference in vulnerability to organic manganese between rats and mice.
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PMID:Chronic organic manganese administration in the rat does not damage dopaminergic nigrostriatal neurons. 287 39

Adrenal glucocorticoids have been shown to produce alterations in the enzymes which synthesize and degrade cholinergic and catecholaminergic neurotransmitters in the central and peripheral nervous system. The present study examined the impact of altering plasma corticosterone levels via corticosterone or metyrapone ingestion, via the drinking water, on the developmental profile of choline acetyltransferase (ChAT), acetylcholine esterase (AChE), tyrosine hydroxylase (TH) and monoamine oxidase (MAO) in various gastrointestinal (GI) segments of rats. Three groups were studied: non-treated, corticosterone treated and metyrapone treated. Drug intake of pregnant (i.e., beginning on the 15th day of gestation), lactating and weaned rats was monitored until the male pups were sacrificed at 1, 3, 7, 14, 21, 35 and 50 days of age. Results showed that ChAT and TH activities peaked earlier in development in corticosterone treated rats as compared to non-treated and metyrapone treated rats. During the early postnatal period plasma corticosterone levels were inversely related to AChE and MAO activities in most GI segments. These results indicate that neurotransmitter enzyme activities in various GI segments are influenced by corticosterone during a critical period of development.
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PMID:Effects of corticosterone and metyrapone on gastrointestinal neurotransmitter enzyme activities. 287 26

We reported recently that chronic thyroid deficiency in rat, beginning in utero and terminating after maturity, suppresses lesion-induced central catecholaminergic axon sprouting in the adult brain [Gottesfeld et al, 1985]. The present work was undertaken to define the critical period of hypothyroidism on subsequent neuronal sprouting. Thyroid hormones deficiency was induced in rats by methimazole during (a) gestational days 8-21 (20 mg/kg/day in the drinking water); (b) postnatal days 1-15 (0.2 or 0.4 mg/pup/day; i.p.), or (c) in the mature animal for 4 weeks (20 mg/kg/day in the drinking water). The olfactory tubercles (OTs) were used as a model to study sprouting of dopaminergic (DA) nerve terminals, elicited by olfactory bulbectomy. Animals in each group received lesions or sham operations as adults, and sacrificed 3 weeks after the operation. Thus, for each of the above treatments four subgroups were formed: (a) euthyroid/sham-operation, (b) euthyroid/lesion, (c) hypothyroid/sham-operation, and (d) hypothyroid/lesion. Sprouting of DA axon terminals in the OTs was identified by biochemical assays and quantitative immunofluorescent microscopy, using tyrosine hydroxylase (TH) as a marker. Serum thyroxine levels served as an index of the thyroid status. The results demonstrate that lesion-induced sprouting of DA axon terminals in OTs of adult rats is suppressed by hypothyroidism induced prenatally or during the early postnatal period, but not after maturity. Thus, there is a perinatal critical period during which altered thyroid function exerts long-term effects on neuronal plasticity.
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PMID:Perinatal, not adult, hypothyroidism suppresses dopaminergic axon sprouting in the deafferented olfactory tubercle of adult rat. 289 38


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