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

Anesthetized dogs, which had been prepared with lumboadrenal vein cannulae, were intravenously infused with monoamine axidase (alphaETA), tryptophan hydroxylase (pCPA) or tyrosine hydroxylase (alphaMT) inhibitors 30 min prior to exposure to 10% oxygen at ground level. These studies were designed to ascertain the role of the neurotransmitters, serotonin and norepinephrine, in the adrenocortical response to hypoxia. In normoxic animals, alphaETA decreased basal cortisol secretion and increased systolic pressure, whereas pCPA and alphaMT were essentially without afffect on these parameters. All inhibitors prevented the rise in cortisol secretion usually observed in hypoxic dogs. Alpha ETA appeared to inhibit the adrenocortical response to hypoxia as a result of its potent pressore activity, while pCPA and alphaMT inhibited cortisol secretion by interfering with the synthesis of serotonin and norepinephrine, respictively. These data suggest that substances which alter the content and/or turnover of brain monoamines abolish the hypoxic rise in cortisol secretion and thus would lower the resistance of the animal to this stressor.
 ...
PMID:Effects of altering monoamine metabolism on the adrenocortical response to hypoxia. 0 52

The developmental variations of tyrosine hydroxylase (TH) and of acetylcholinesterase (AChE) were studied in embryonic and post-hatching chicken sympathetic ganglia. Different levels of TH activity were found in two different flocks of White Leghorn chicken, which are probably dependent on genetic differences. These enzymatic differences, however, do not become apparent before hatching and may indicate a combined effect of genetic variation and functional demands. During the period of incubation, TH activity is characterized by a pronounced and steady increase from the twelfth day of incubation up to day 2 after hatching. This corresponds to a period of intense maturation of the sympathetic neuron. In the period following hatching, the 'fourth day fall phenomenon' previously described by us for DOPA decarboxylase (DDC), dopamine-beta-hydroxylase (DBH), and monoamine oxidase (MAO) is not seen in the TH curve. Instead, TH activity tends to remain constant between days 2 and 14 after hatching (ah). Both ganglionic protein and weight remain constant in this period, indicating a phase of general pause in protein synthesis. AChE activity increases steadily from the eighth until the twenty-first day of incubation. A sudden and significant drop in AChE activity was found at day 2 ah followed by a period of rapid increase at day 3 ah and a levelling of activity up to day 30 ah. Comparing the present variations to those observed in our previous studies on DBH, a temporal relationship between TH and DBH activity is observed during the phases of synaptogenesis and maturation but not during the phase of intense functional activity. Our results strongly suggest that before hatching in chick embryo sympathetic ganglia, the cholinergic presynaptic terminals play a role in regulating the development of the adrenergic neurons. In the period following hatching, however, the DBH and TH levels in cell bodies seem to be principally regulated by the functional activity. This results in depletion of DBH, but not TH, through liberation along with the neurotransmitter at the periphery. Depletion of DBH at the terminals may result in increased transport and thereby depletion in the cell body. This mechanism is probably responsible for the difference in the profiles of activity of DBH and TH in the cell bodies observed in the first week after hatching.
 ...
PMID:Developmental variations of tyrosine hydroxylase and acetylcholinesterase in embryonic and post-hatching chicken sympathetic ganglia. 0 67

1 The effects of chronic nicotine administration (1 or 10 mg/kg, s.c., twice daily) were studied in intact and denervated rat adrenal glands to determine the relative roles of central input and direct actions on catecholamines. 2 Catecholamine depletion was obtained in the intact glands from 1-7 days of treatment with 10 mg/kg, with recovery by 14 days of treatment; catecholamines were not decreased in denervated adrenal glands. 3 Catecholamine depletion was accompanied by a decline in functional storage vesicles (determined by [3H]-adrenaline uptake per gland) in the intact side, while no change was seen in the denervated side; the proportion of newly synthesized vesicles increased markedly during 1-7 days of treatment with 10 mg/kg in the intact side, while a much smaller increase of shorter duration was seen in the denervated adrenal gland. 4 Chronic nicotine administration at either dose level induced tyrosine hydroxylase in both intact and denervated glands, but the increase occurred more slowly in the denervated glands. 5 Dopamine beta-hydroxylase levels increased similarly in both sides during treatment with nicotine (10 mg/kg). 6 These studies suggest that although long-term adrenal denervation eliminates the catecholamine depletion caused by chronic administration of nicotine, the mechanisms for induction of catecholamine synthesizing enzymes are still capable of responding to the drug.
 ...
PMID:Effects of chronic nicotine administration on the denervated rat adrenal medulla. 0 49

The role of target organs in the maturation of adrenergic neurons was studied in the neonatal rat. The superior cervical ganglion (SCG) and its end organs, the salivary glands and iris were employed as a model system. Unilateral sialectomy and iridectomy in 3-day-old animals prevented the normal development of ganglion tyrosine hydroxylase (T-OH) and DOPA decarboxylase activities. These enzymes are highly localized to adrenergic neurons in the SCG, and were used to monitor maturation of these cells. Enzyme activity remained depressed for at least two months, the longest time tested. In contrast, total ganglion protein, a measure of ganglion growth as a whole, initially developed normally. Six weeks after surgery, however, protein content was significantly lower in ganglia deprived of the normal field of innervation. Failure of normal enzyme maturation was apparently dependent on removal of ipsilateral end organs only, since bilateral sialectomy exerted no greater effect than unilateral sialectomy. In adults, unilateral sialectomy and iridectomy did not significantly alter ganglion T-OH activity or protein in rats followed up to one month after surgery.
 ...
PMID:The effect of taget organ removal on the development of sympathetic neurons. 0 64

Sensitive radiometric assays for tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH), phenylethanolamine-N-methyl transferase (PNMT), and glutamic acid decarboxylase (GAD) have been combined with microdissection techniques for quantitative localization of these synthetic enzymes in rabbit spinal cord. TH was present uniformly in gray and white matter. DBH was higher in the lateral horns than in the other gray matter areas, and was not detectable in white matter. PNMT was detectable in gray but not white matter, and was considerably lower in activity than the other catecholamine synthetic enzymes. GAD was higher in the dorsal horns at the cervical and lumbar levels than in other gray matter areas and relatively low in white matter. GAD activity was considerably higher than the catecholamine synthetic enzyme activities. The quantitative localizations are consistent with the qualitative immunohistochemical enzymes maps and distributions of the related putative neurotransmitters.
 ...
PMID:Quantitative localization of tyrosine hydroxylase, dopamine-beta-hydroxylase, phenolethanolamine-N-methyl transferase, and glutamic acid decarboxylase in spinal cord. 0 66

The action of prostaglandin E1 on tyrosine hydroxylase activity in adrenal slices of guinea pig was studied. The activity of tyrosine hydroxylase and was decreased by the incubation of adrenal slices with prostaglandin E1 at concentrations beyond 2 mug per ml for 2 hours. The activity of tyrosine hydroxylase was stimulated by dibutyryl adenosine 3',5'-monophosphate in slices of guinea pig adrenal glands. Incubation of adrenal slices wtth the combination of PGE1 and DBc-AMP lead to a tyrosine hydroxylase activity higher than that with PGE1 alone, but not as great as DBc-AMP alone. It was suggested that PGE1 inhibited the enzyme activity independently of the cyclic AMP level. Other prostaglandins such as PGA1 and PGB1 were deficient to the extent that the tyrosine hydroxylase activity was decreased. PGE1 inhibited the enzyme activity much to the same extent seen with protein synthesis inhibitors such as cycloheximide and actinomycin D. However, PGE1 did not influence the incorporation of L-leucine-14C into acid insoluble protein. The studies reported here showed that PGE1 inhibited the synthesis of tyrosine hydroxylase.
 ...
PMID:Regulation of tyrosine hydroxylase activity by prostaglandin E1 in guinea pig adrenal gland. 0 75

The pathogenesis of hepatic encephalopathy has been investigated in a two-stage devascularization model in the rat with portavacal shunt and hepatic artery ligation. There is a significant increase in brain octopamine and phenylethanolamine and a decrease in brain norepinephrine (NE) 6 to 9 hours after hepatic artery ligation. The depletion of NE seems the sequel of diminished synthesis in the presence of an unaltered turnover rate, due to a blockade of tyrosine hydroxylase either by accumulation of false neurochemical transmitters or by phenylalanine. It is most marked in the cortex and midbrain. The high-energy phosphate compounds, ATP, phosphocreatine and glucose-6-phosphate are not diminished in hepatic coma, nor is glucose, indicating that other mechanism are involved in the pathogenesis of metabolic state by the increased ammonia level. "intestinal sterilization" and total colectomy have no significant effect on the ammonia level, but cause a decrease in the level or aromatic precursor amino acids in the plasma and brain, with normalization of the level of cerebral transmitters. These results permit the formulation of a unified concept of the hepatic coma syndrome and its clinical manifestations such as flapping tremor, the hyperdynamic cardiovascular state and the hepatorenal syndrome. Moreover, they form the basis for the introduction of a new therapeutic principle in the management of hepatic encephalopathy by L-dopa or modified amino acid solutions, which act by altering the central and peripheral neurotransmitters.
 ...
PMID:[Cerebral manifestations in the hepatic coma syndrome (author's transl)]. 0 92

The activity of a partially purified preparation of tyrosine hydroxylase (EC 1.14.16.2) from the bovine caudate nucleus was increased by heparin, chondroitin sulfate, phosphatidylserine, polyacrylic acid, polyvinyl sulfuric acid and both poly-D-, and poly-L-glutamic acids, all polyanions. A variety of salts both activated the enzyme and prevented the activation by the polyanions. The observations that activity is increased when the enzyme interacts with salts and with macromolecules of high negative charge density are used to infer a model for these interactions and for the structural change in the enzyme that accompanies activation.
 ...
PMID:Activation of tyrosine hydroxylase by polyanions and salts. An electrostatic effect. 0 22

Tyrosine hydroxylase and dopamine-beta-hydroxylase have been measured in 34 discrete areas and nuclei of the limbic system of the rat. Both enzymes showed an uneven distribution in this system. The ratio between tyrosine hydroxylase and dopamine-beta-hydroxylase activities showed a significant correlation when compared with the ratio of dopamine and norepinephrine concentrations for the areas studied. The results strongly suggest that dopaminergic terminals are present in discrete areas of the limbic cortex, and several septal and amygdaloid nuclei, and allow the precise localization of dopaminergic and noradrenergic areas in the limbic system.
 ...
PMID:Tyrosine hydroxylase and dopamine-beta-hydroxylase: distribution in discrete areas of the rat limbic system. 0 97

Attempts were made to find a biochemical correlate with previously observed behavioral alterations after administration of alpha-melanocyte-stimulating hormone (MSH) and MSH release-inhibiting factor (MIF-I). Brains of intact and hypophysectomized (hypox) rats were analyzed for endogenous catecholamine levels and the disappearance rate of endogenous norepinephrine (NE) after treatment with the tyrosine hydroxylase inhibitor alpha-methyl-para-tyrosine (AMPT). The studies undertaken show the following: (1) After the injection of MSH (100 mug/kg IP daily x 3) and AMPT, samples in different groups of intact and hypox rats were taken at 0, 1, 2, 4 and 6 hrs in 7 different brain areas. In the mid-brain area for the intact group of rats, the rate of disappearance of NE was faster and for the hypox rats it was slower than the rate for control rats not treated with the peptides. NE levels in the same area at time 0 were 11 percent lower than controls in hypox rats and unchanged in unoperated animals. (2) After the injection of MIF-I (20 mg/kg IP daily x 3) in similar experiments as with MSH, a reduced rate (p less than 0.05) of NE disappearance for the first 4 hr and an increased rate (p less than 0.05) of NE disappearance for the last 2 hr of the experiments occurred for both the intact and hypox rats in the mid-brain area where endogenous NE levels were lowered by 11 and 12 percent at 0 min. In no other brain areas were alterations in NE breakdown found in both the intact and hypox rat groups. Behavioral changes have been found previously under similar experimental conditions in both intact and hypox rats. (3) Rates of dopamine disappearance in experiments similar to those described for NE disappearance indicated that in the striatal brain area no change was found in the intact rats after either MSH or MIF-I, whereas a decrease in DA disappearance was found for hypox rats during the six hour experimental period only after MSH. The results indicate that a correlation between behavioral changes, rates of disappearance and endogenous levels of NE in the mid-brain area may occur after MIF-I at the times examined but that a similar correlation for MSH did not appear likely.
 ...
PMID:Alpha-MSH and MIF-I effects on catecholamine levels and synthesis in various rat brain areas. 0 15


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>