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)

Indirect immunofluorescence histochemistry was used to study the relation among GABAergic, catecholaminergic, cholinergic, and peptidergic neurons in the rat mediobasal hypothalamus. By employing a direct double-labelling procedure using sheep antiserum against glutamic acid decarboxylase (GAD), mouse monoclonal and rabbit antibodies to neurotensin (NT) and rabbit antisera to tyrosine hydroxylase (TH), choline acetyltransferase (ChAT), galanin (GAL), growth hormone-releasing factor (GRF), or somatostatin (SOM), it was demonstrated that GAD-positive fibers and terminals in the external part of the median eminence co-contained immunoreactivity for TH, NT, GAL or GRF, but not for SOM. In the internal part of the median eminence-infundibular stalk, GAD-positive/NT-, GAL-, and GRF-negative and GAD-positive/TH-positive fiber plexa were shown. When a recently developed direct triple-labelling procedure with biotin-conjugated mouse secondary antibodies in conjunction with diethylaminocoumarin (DAMC)-conjugated avidin was employed, presence of GAD/GAL/NT- as well as GAD/GRF/NT-containing varicosities could be demonstrated close to hypophysial portal vessels. In colchicine-pretreated animals, GAD was shown to coexist with TH, NT, or GAL in cell bodies in both the dorsomedial and ventrolateral domains of the arcuate nucleus, but with GRF only in the ventrolateral division. ChAT-positive neurons in the ventrolateral region were also TH-positive. In the ventrolateral arcuate nucleus, triple-labelling followed by elution-restaining showed GAD/NT/GAL/TH-immunoreactivities in the same cells. Similarly, double-labelling with two following elution-restaining steps showed several NT/GAL/GRF/TH-containing cell bodies in this part of the arcuate nucleus. GAD-positive cells in the anterior hypothalamic periventricular area and fibers in the pituitary neurointermediate lobe were also TH-positive. The results demonstrate complex patterns of storage of chemical messengers in neurons of the arcuate nucleus-median eminence complex. Possible neuroendocrine interactions of these systems in the control of prolactin and growth hormone secretion are discussed.
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PMID:Peptide- and transmitter-containing neurons in the mediobasal hypothalamus and their relation to GABAergic systems: possible roles in control of prolactin and growth hormone secretion. 290 36

Seven cell specific marker enzymes in brain and optic nerve and morphological evaluation by light microscopy were used to characterize the neurotoxicity associated with exposure of rats to hexachlorophene (HCP; 40 mg/kg/day, po, for 9 days). In vitro exposure to HCP at concentrations up to 100 microM had no direct inhibitory effect on the marker enzymes, validating their use in evaluating brain function in vivo. Rats exhibited a reduction in body weight gain, weakness, and ataxia of the hind limbs by the ninth day of HCP exposure. At 24 hr following the last day of exposure to HCP, the activities of the three neuron specific enzymes, glutamic acid decarboxylase, tyrosine hydroxylase, and choline acetyltransferase, in rat brain were unchanged from those of the vehicle-treated control group. Of the two astroglial enzyme markers measured, a small but significant increase was observed in the activity of nonneuronal enolase in the cerebellum and glutamine synthetase in the hippocampus of HCP-treated rats. The optic nerve appeared to be the most sensitive tissue in that the activity of both the astroglial marker, nonneuronal enolase, and the myelin marker, 2',3'-cyclic nucleotide phosphohydrolase, was significantly decreased following HCP exposure. This decrease in enzyme activity is consistent with the histological observations demonstrating extensive vacuolization and edema in the optic nerve after exposure to HCP.
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PMID:Effect of short-term exposure to hexachlorophene on rat brain cell specific marker enzymes. 290 23

The GABAergic properties of dissociated neurons from cerebral cortex of neonatal rats were studied in primary culture using electrophysiological, biochemical and immunohistochemical methods. Cultured neurons had a resting potential of -50 to -60 mV and exhibited spontaneous excitatory and inhibitory synaptic currents. Non-spontaneous (elicited) ionic currents were produced by direct application of GABA and glutamate. Cultures contained measurable amounts of GABA from the first day in culture; GABA content reached a plateau around the 10th day of culture, and continued, nearly unchanged, until the 21st day of culture. Immunohistochemistry showed that 45% of the total cells in culture contained glutamic acid decarboxylase (GAD). Octadecaneuropeptide (ODN), a putative neuroregulatory peptide for benzodiazepine recognition sites, was present in approximately 28% of all neurons. Ninety-three percent of ODN-positive cells demonstrated GABAergic properties as well by displaying GAD-immunoreactivity. The peptide GABA-modulin (GM), a putative GABA receptor modulator, was found in about 75% of all neurons, with a further 65% of these cells exhibiting GAD-immunoreactivity. Cells immunopositive for neuropeptide Y (NPY), somatostatin (SRIF), and cholecystokinin-octapeptide (CCK), were found at much lower incidence (1-4%). Double-labelling studies showed that 90-97% of the cells positive for NPY, SRIF and CCK were also positive for GAD. Cells immunoreactive with serotonin or tyrosine hydroxylase were not detected. We suggest that primary cultures of neonatal cortical neurons may provide a useful experimental model to investigate the function and the modulation of GABAergic neurotransmission in the cerebral cortex.
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PMID:Subsets of GABAergic neurons in dissociated cell cultures of neonatal rat cerebral cortex show co-localization with specific modulator peptides. 337 69

Fetal neuronal cells dissociated from mouse hypothalamus are able to grow in a serum-free medium for two to four weeks. Several neuronal activities have been measured during the in vitro cell development. Whereas glutamic acid decarboxylase (EC 4.1.1.15) activity disappears, those of thyroliberin (TRH) and tyrosine hydroxylase (EC. 1.14.16.2) remain stable, and acetylcholine transferase one (EC 2.3.1.6) rises earlier than in a serum supplemented medium. These results show that primary cultures grown in serum-free medium offer a promising model for studying neuronal activity differentiation.
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PMID:[Demonstration of neuronal activities in primary cultures from fetal mouse hypothalamus maintained in a serum-free medium]. 610 44

In rats, glutamic acid decarboxylase activity increased in the proximal portion of the optic nerve after its ligation, whereas the activities of choline acetyltransferase and tyrosine hydroxylase remained constant. Possible centrifugal neurons to the retina are GABAergic.
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PMID:The possibility of centrifugal projections to the retina in the rat. 611 May 62

Young adult (8 months) and aged (26 months) female Wister rats were tested in a 12-arm radial maze in which the optimal strategy was to enter all arms without a repetition. In order to determine if possible age-associated alterations in behavior were correlated with defects in cholinergic. GABAergic and adrenergic neurons in the hippocampus and cerebral cortex, the activities of choline acetyltransferase (CAT), glutamic acid decarboxylase (GAD) and tyrosine hydroxylase (TH) were assayed in these regions of all animals after testing in the radial maze. In the maze, the aged rats continued to perform at the chance level after 15 trials, whereas the young rats had virtually mastered the task. The only significant neurochemical age effect was an increase in hippocampal TH. However, analysis of individual differences among rats revealed positive correlations between maze performance and hippocampal CAT in the aged group and cortical GAD in both the young and aged groups.
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PMID:Age and neurochemical correlates of radial maze performance in rats. 611 26

In order to confirm the multiple neurotransmitter biosynthetic ability, the possibility to separation of the activities of tyrosine hydroxylase (TH), choline acetyltransferase and glutamic acid decarboxylase was tested by subcloning of a clonal rat pheochromocytoma PC12 cell line. All of 9 subclones obtained showed significant activities of above 3 enzymes, indicating that the PC12 cell has multi-functional properties of neurotransmitter syntheses. One of the subclones, designated PC12h, was demonstrated to have nerve growth factor- (NGF) responsive TH activity. The ED50 value of NGF to increase the TH activity was 1.7 ng/ml (6.5 X 10-11 M). A simultaneous addition of saturating amounts of NGF (50 ng/ml) and dexamethasone (10-6 M) resulted in the increase of TH activity that is equal to the sum of those achieved when either effector was added separately, indicating that the NGF- mediated increase of TH activity in PC12h cells was independent upon the effect of dexamethasone. And also, the TH activity increased by NGF was somewhat potentiated in PC12h cells cultured in a hormone- supplemented serum-free medium.
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PMID:Nerve growth factor-mediated stimulation of tyrosine hydroxylase activity in a clonal rat pheochromocytoma cell line. 611 17

The activity of choline acetyltransferase is over twice as high in the hippocampus of Wistar Kyoto (WKY) than in Brown Norway (BN) rats, and this is paralleled by a comparable difference in acetylcholinesterase staining intensity within the hippocampal formation. However, the size of the whole hippocampus is smaller in WKY than in BN rats. There are no strain differences in the activities of the neurotransmitter-synthesizing enzymes: tyrosine hydroxylase in the septum and glutamic acid decarboxylase in the hippocampus. The findings indicate the existence of strain-dependent inverse relationship between the septo-hippocampal cholinergic system and the size of the hippocampus.
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PMID:Stain-dependent differences between the septo-hippocampal cholinergic system and hippocampal size. 611 23

Unilateral injection of 5,7-dihydroxytryptamine (DHT) into the rat neostriatum markedly reduced not only striatal tryptophan hydroxylase (TPH) activity but also striatal tyrosine hydroxylase (TH) activity and dopamine (DA) concentration measured 10--15 days later. The decrease in striatal TH activity was dose related over the range of 8--32 micrograms of DHT; a dose of 16 micrograms reduced striatal TH activity to 40--50% of control, DA concentration to 38% of control, and TPH activity to 5--20% of control. Intrastriatal injection of 16 micrograms of DHT reduced TH activity in the ipsilateral substantia nigra to 51% of control. Pretreatment with amfonelic acid, a potent DA uptake inhibitor, significantly reduced the effect of DHT on striatal and nigral TH activity and striatal DA concentration without affecting the DHT-induced decrease in striatal TPH activity. Desmethylimipramine (5 and 25 mg/kg) had no effect on the DHT-induced decrease in striatal TH activity. Striatal choline acetyltransferase and glutamic acid decarboxylase activities were not decreased by 16 micrograms of DHT. The results indicate that DHT can alter dopaminergic function in the rat neostriatum through a direct effect of the drug on DA neurons.
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PMID:Biochemical evidence for alteration of neostriatal dopaminergic function by 5,7-dihydroxytryptamine. 612 Oct 11

The greater activity of tyrosine hydroxylase (TH) in substantia nigra and corpus striata of adult BALB/cJ than CBA/J mice, is attributable to differences in the number of dopamine neurons in the ventral midbrain tegmentum. To determine if strain differences in TH activity develop postnatally we have measured the development of TH in the midbrain (SN) and in the corpus striatum (CS). In the midbrain neonatal TH activity was 20% of adult levels. Thereafter, TH activity increased rapidly achieving adult levels by 11 days. A 25% "overshoot' above adult values at 15 days was followed by a gradual decrease to adult activity at 4 weeks. In the CS neonatal activity was about 10% of adult levels and increased slowly to reach adult values at 4 weeks. Striatal choline acetyltransferase (CAT) activity in the neonate was only 3.7% of adult values and at 21 days had only reached 70% of adult activity. Neonatal glutamic acid decarboxylase (GAD) activity was relatively high in both brain regions and increased gradually to adult activity by 4 weeks. Strain differences in TH activity were not present at birth but first appeared at 9 days in SN and 11 days in CS. Once established, the differences were maintained. These results suggest that strain differences in TH are most probably a consequence of differences in postnatal neuron survival, although the possibility that some neurons lose their phenotypic expression of TH cannot be excluded.
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PMID:Time of appearance during development of differences in nigrostriatal tyrosine hydroxylase activity in two inbred mouse strains. 612 48


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