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)

The effects of drinking saline for 7 days on the mass and in situ activity of tyrosine hydroxylase (TH) in the median eminence (ME) and superior cervical ganglion (SCG) of rats were investigated. TH mass was quantified by immunoblot assay. In situ TH activity was calculated from the rate of intracellular accumulation of L-dihydroxyphenylalanine (DOPA). In rats that drank 10 mM, 30 mM, and 100 mM NaCl for 7 days, TH activity in the ME was 34 +/- 4, 36 +/- 5, and 45 +/- 3 (mean and S.E.M.) mol of DOPA.h-1.mol of TH-1, respectively, compared to 30 +/- 2 for rats that drank water. The activity of TH in the SCG of animals that drank 10 mM, 30 mM, and 100 mM NaCl was 143 +/- 24, 167 +/- 12, and 272 +/- 13 mol DOPA.h-1.mol TH-1, respectively, compared to 119 +/- 10 for animals that drank water. The mass of TH in the ME and SCG decreased as a function of the concentration of NaCl in the drinking water. In animals that drank water, 10 mM, 30 mM, and 100 mM NaCl, the amounts (pmol) of TH were, respectively, 0.28 +/- 0.03, 0.31 +/- 0.04, 0.23 +/- 0.02, and 0.21 +/- 0.01 per ME and 0.67 +/- 0.06, 0.72 +/- 0.11, 0.37 +/- 0.01, and 0.34 +/- 0.02 per SCG. TH activity in the ME or SCG was unaffected by treatment for 7 days with arginine vasopressin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Saline ingestion stimulates the in situ molar activity of tyrosine hydroxylase in the median eminence and superior cervical ganglion. 289 32

Biphasic electrical field stimulation (0.5-5 Hz, 2 ms, 25 V, 3 min) and high K+ (10-30 mM, 5 min) released endogenous 3,4-dihydroxyphenylalanine (DOPA) from superfused rat striatal slices. Characteristics of the DOPA release were compared with those of 3,4-dihydroxyphenylethylamine (dopamine, DA). Electrical stimulation at 2 Hz evoked DOPA and DA over similar time courses. alpha-Methyl-p-tyrosine (0.2 mM) markedly reduced release of DOPA but not of DA. Maximal release (0.3 pmol) of DOPA was obtained at 2 Hz and at 15 mM K+. The impulse-evoked release of DOPA and DA was completely tetrodotoxin (0.3 microM) sensitive and Ca2+ dependent and the 15 mM K+-evoked release was also Ca2+ dependent. On L-[3,5-3H]tyrosine (1 microM) superfusion, high K+ (15 and 60 mM) released DOPA and DA together with concentration-dependent decreases in tyrosine 3-monooxygenase (EC 1.14.16.2) activity as indicated by [3H]H2O formation, followed by concentration-dependent increases after DOPA and DA release ended. These findings suggest that striatal DOPA is released by a Ca2+-dependent excitation-secretion coupling process similar to that involved in transmitter release.
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PMID:Transmitter-like release of endogenous 3,4-dihydroxyphenylalanine from rat striatal slices. 289 24

This paper compares noradrenaline content in the different parts of the oviduct in rabbits receiving or not a dose of estradiol-17 beta 24 h before human chorionic gonadotropin (HCG) and killed 60 h post HCG. 3,4-Dihydroxyphenylalanine assays were carried out in the oviduct after aromatic L-amino acid decarboxylase was inhibited by m-hydroxybenzylhydrazine (NSD 1015) in the same experimental conditions. Pauerstein et al. (1974) have shown that an intramuscular injection of 250 micrograms of estradiol-17 beta in rabbits 24 h before intravenous injection of 100 IU of HCG delays ovum transport at the ampullary-isthmic junction. The extent of this noradrenergic innervation suggested that estradiol could act at least partially through the noradrenergic systems. Our results show that estradiol-17 beta increased oviduct weight by water retention without modifying either the tyrosine hydroxylase activity or the noradrenaline content in any part of the oviduct and that, consequently, the estrogen-induced "tube locking" of ova was not mediated through the noradrenergic processes.
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PMID:Preovulatory injection of estradiol-17 beta: effect on noradrenaline activity in different parts of the rabbit oviduct. 311 22

Previous studies in this laboratory have indicated that chronic lead (Pb) exposure during development induces a neurotoxicity in dopamine (DA) neurons that is primarily presynaptic in nature and at least partially related to altered regulation of DA synthesis. A primary form of DA synthesis regulation is the inhibition exerted on synaptic tyrosine hydroxylase activity via dopaminergic autoreceptors. This study assessed the functional status of this mechanism in Pb-exposed rats employing a pharmacological model. At parturition dams received 0.2% Pb acetate (1090 ppm) in the drinking water while control dams received distilled water. Offspring were weaned to and maintained on the same solution given their dams until termination at 125 days. Rats were given saline or 6,7-dihydroxy-2-dimethylaminotetralin (TL-99, 2.5-20 mg/kg ip) 40 min before termination followed 10 min later by 750 mg/kg ip of gamma-butyrolactone (GBL) or saline. The ability of TL-99 to prevent the GBL-induced increase in DA content was significantly diminished in nucleus accumbens (NAc) of exposed rats compared to controls, indicating that chronic Pb impairs receptor-mediated regulation of DA synthesis in mesolimbic neurons. No effect of Pb was observed in caudate-putamen. In animals receiving only saline injections concentrations of the DA metabolites, homovanillic acid and dihydroxyphenylacetic acid, were significantly decreased by Pb in the range of 17-31% and 12-24%, respectively. DA content was also significantly diminished by Pb in ventral tegmental area of these latter groups. These findings suggest that chronic Pb has multiple actions on central nervous system dopaminergic neurons consisting of an impaired regulation of DA synthesis that is apparently independent of a decrease in DA release.
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PMID:Diminished regulation of mesolimbic dopaminergic activity in rat after chronic inorganic lead exposure. 318 11

The effect of daily doses of 80 mg/kg (intraperitoneal) of alpha-methylparatyrosine, AMPT (inhibitor of tyrosine hydroxylase) on the voluntary consumption of ethanol, water, and solid food was studied in rats of both sexes belonging to the UChA (lower ethanol consumer) and UChB (high ethanol consumer) strains. The consumptions during the treatment period were compared to those of the preceding one (basic). Decrease of ethanol and solid food intake and increase of that of water in UChB rats and only a decrease of solid food intake in UChA rats were observed. These effects cannot be ascribed to blocking of dopaminergic or noradrenergic synapses, since this dose of AMPT inhibits the in vivo synthesis of both catecholamines.
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PMID:Effects of alpha-methylparatyrosine on voluntary consumption of ethanol, water, and solid food in UChA and UChB rats. 330 85

Vasopressin (AVP) in acute experiments has been shown to influence cardiovascular reflexes, but the effect of a more prolonged administration of AVP on the sympathetic nervous system has not been investigated. Long-Evans rats were treated for 7 days with AVP (Pitressin tannate in oil, with single daily doses of 100 or 500 mU.100 g-1, s.c.) to determine whether AVP alters norepinephrine (NE) turnover in kidney, intestine, or skeletal muscle. Control rats were given equal doses of peanut oil daily. NE turnover was determined by measuring the decline in tissue levels of NE for 8 h after inhibition of tyrosine hydroxylase with alpha-methyl-p-tyrosine (300 mg.kg-1, i.p. every 4 h). Measurements of water intake, urine output, and urine osmolality showed that chronic administration of the high dose, but not the low dose, of AVP produced maintained increases in urine osmolality and decreases in water intake and urine output. Body weight, plasma osmolality, plasma electrolytes, and hematocrit were not significantly altered by AVP treatment, but mean arterial pressure was elevated significantly (control, 105 +/- 3 mmHg versus AVP, 119 +/- 4 mmHg, p less than 0.05) (1 mmHg = 133.3 Pa) in the high dose group. Plasma renin activity was decreased slightly, but significantly in rats treated with the high dose of AVP. Compared with results in control animals, there were no statistically significant changes in NE turnover after chronic administration of either the low or the high dose of AVP. The results indicate that administration of AVP for 7 days to rats in normal fluid balance does not result in a decrease in NE turnover in peripheral organs.
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PMID:Effect of short-term administration of vasopressin on arterial pressure and norepinephrine turnover in Long-Evans rats. 342 48

Water was chosen as the optimal medium for the extraction of tyrosine hydroxylase (TH) from rat brain. Determination of TH activity in crude homogenates failed to exhibit a linear relationship between enzyme concentration and measured activity, however, when a supernatant was used, a linear relationship existed. At a time when TH activity is maximally increased in the locus coeruleus after reserpine treatment (Reis et al 1975; Zigmond.1979) (2.5 mg kg-1 day-1 for 3 days, kill 24 h after last dose) we could detect no alterations in whole brain TH, however if treatment continued for 4 days and animals were killed 72 h after the last dose it was possible to detect increases in TH activity in various brain regions. These results suggest that local changes in brain TH activity are not revealed in measurements made on whole brain. The early rise in blood pressure, following the administration of deoxycorticosterone acetate (doca) and 1% NaCl to male Wistar rats, was accompanied by bradycardia. Whole brain Th activity was determined in these hypertensive animals 6-21 days after the commencement of treatment and the results failed to confirm the reported elevation of TH activity (Rylett et al 1976). The results are discussed with reference to the TH assay employed.
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PMID:Whole brain tyrosine hydroxylase activity during the development of deoxycorticosterone acetate-1% sodium chloride-induced hypertension in rats. 611 31

The role of renal nerves in influencing the control of arterial pressure was studied in Wistar rats with aortic depressor nerve (ADN) transection. Renal denervation prevented or reversed the normal increase in arterial pressure seen after ADN transection. This effect was not due to an effect on the renin-angiotensin system, as the elevated arterial pressure after ADN section in rats with renal nerves intact was shown to be due to increased alpha-adrenergic activity. Food and water intake and urine output decreased significantly in both renal-denervated and sham-denervated rats after ADN section, suggesting that a pressure diuresis mechanism was not responsible for preventing the rise in pressure in renal-denervated rats. In another study, the concentration of norepinephrine in skeletal muscle and hypothalamus at 0 and 8 hours after inhibition of tyrosine hydroxylase with alpha-methyltyrosine was used as an index of norepinephrine turnover. Norepinephrine turnover in skeletal muscle was increased significantly over control values by ADN transection in sham renal-denervated rats, but was not significantly different from controls in renal-denervated rats with ADN section. In the hypothalamus, there was a significant difference between the turnover of norepinephrine in the two groups of ADN-sectioned rats. The results taken together suggest that renal denervation prevents the arterial pressure response to ADN transection by altering the central mechanisms governing sympathetic outflow. It is suggested that this effect may be due to elimination of information carried by afferent renal fibers.
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PMID:Effect of renal denervation on arterial pressure in rats with aortic nerve transection. 613 68

Chronic manganese poisoning is characterized by mental and extrapyramidal disturbances. Parkinsonism-dementia complex (PD) on Guam is also manifested by progressive extrapyramidal syndrome and dementia. In PD, the reduced activities of catecholamine synthesizing enzymes in the brain has been demonstrated. On the other hand, the soil and water in Guam are rich in manganese, and one of the possible etiologic factors is trace element dysmetabolism in PD. The purpose of this paper is to clarify the effect of chronic manganese loading on the central nervous system. Manganese chloride (10 mg/ml of demineralized and distilled water) was administrated orally to Wistar female rats weighing 80-110 g. Six and 12 months after the administration, manganese loaded and control rats were sacrificed by perfusion for histological studies and by decapitation for the assay of tyrosine hydroxylase (TH) activity. The striatum, globus pallidus and substantia nigra were examined with electron microscopy. The brain for TH assay was dissected into four parts as the striatum, midbrain-thalamus, pons-medulla oblongata, and hypothalamus. Ultrastructural changes were overwhelmingly detected in the zona reticulata of the substantia nigra at 12 months. These changes were mainly composed of alterations of the postsynapse and neuronal soma--shrunken and electron dense dendrites accumulated degenerating materials and so-called simple atrophy of the neuron. Alterations in the presynapse were extremely milder than those in the postsynapse and neuron. At both 6 and 12 months, no significant changes in the striatum and globus pallidus were detected except for irregular windings of the plasma membrane in the axon terminal of the globus pallidus at 12 months.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Histopathological alteration of the central nervous system in rats, following long-term administration of manganese chloride--relation to the activity of the brain tyrosine hydroxylase]. 614 19

We trained rats to circle for a sucrose water reward and found that this behavior is associated with a unilateral increase in the activity of caudate tyrosine hydroxylase, the rate-limiting enzyme for dopamine synthesis. The increase in tyrosine hydroxylase activity occurs in caudate contralateral to the circling direction and the change is transient, increasing during the first 20 min of circling but then plateauing and falling as turning slows. Enhanced synthetic capacity is followed by increases in the contents of dopamine and dihydroxyphenylacetic acid in the contralateral caudate nucleus. These observations are the first evidence for specific activation of a neurotransmitter synthetic enzyme during voluntary motor behavior.
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PMID:Unilateral activation of caudate tyrosine hydroxylase during voluntary circling behavior. 614 59


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