Tyrosine hydroxylase-containing neurons in the spinal cord of the chicken. I. Development and analysis of catecholamine synthesis capabilities

1996 ◽  
Vol 16 (6) ◽  
pp. 625-648 ◽  
Author(s):  
James A. Wallace ◽  
Audrey A. Romero ◽  
Anna M. Gabaldon ◽  
Victoria A. Roe ◽  
Sandra L. Saavedra ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Tyrosine Hydroxylase ◽  
Catecholamine Synthesis

scholarly journals Dehydroepiandrosterone Sulfate and Allopregnanolone Directly Stimulate Catecholamine Production via Induction of Tyrosine Hydroxylase and Secretion by Affecting Actin Polymerization

Endocrinology ◽  
2005 ◽  
Vol 146 (8) ◽  
pp. 3309-3318 ◽  
Author(s):  
I. Charalampopoulos ◽  
Ε. Dermitzaki ◽  
L. Vardouli ◽  
C. Tsatsanis ◽  
C. Stournaras ◽  
...  
Keyword(s):  
Tyrosine Hydroxylase ◽  
Actin Filament ◽  
Chromaffin Cells ◽  
Actin Polymerization ◽  
Dehydroepiandrosterone Sulfate ◽  
Neuroactive Steroids ◽  
Zona Reticularis ◽  
Catecholamine Synthesis ◽  
Catecholamine Levels

Abstract Adrenal cortical cells of zona reticularis produce the neuroactive steroids dehydroepiandrosterone (DHEA), its sulfate ester dehydroepiandrosterone sulfate (DHEAS), and allopregnanolone (ALLO). An interaction between zona reticularis and adrenal medulla has been postulated based on their close proximity and their interwoven borders. The aim of this paper was to examine in vitro the possible paracrine effects of these steroids on catecholamine production from adrenomedullary chromaffin cells, using an established in vitro model of chromaffin cells, the PC12 rat pheochromocytoma cell line. We have found the following: 1) DHEA, DHEAS, and ALLO increased acutely (peak effect between 10–30 min) and dose-dependently (EC50 in the nanomolar range) catecholamine levels (norepinephrine and dopamine). 2) It appears that the acute effect of these steroids involved actin depolymerization/actin filament disassembly, a fast-response cellular system regulating trafficking of catecholamine vesicles. Specifically, 10−6m phallacidin, an actin filament stabilizer, completely prevented steroid-induced catecholamine secretion. 3) DHEAS and ALLO, but not DHEA, also affected catecholamine synthesis. Indeed, DHEAS and ALLO increased catecholamine levels at 24 h, an effect blocked by l-2-methyl-3-(-4hydroxyphenyl)alanine and 3-(hydrazinomethyl)phenol hydrochloride, inhibitors of tyrosine hydroxylase and l-aromatic amino acid decarboxylase, respectively, suggesting that this effect involved catecholamine synthesis. The latter hypothesis was confirmed by finding that DHEAS and ALLO increased both the mRNA and protein levels of tyrosine hydroxylase. In conclusion, our findings suggest that neuroactive steroids exert a direct tonic effect on adrenal catecholamine synthesis and secretion. These data associate the adrenomedullary malfunction observed in old age and neuroactive steroids.

Abnormalities in Enzymes Involved in Catecholamine Synthesis and Catabolism in Phaeochromocytoma

1977 ◽  
Vol 53 (6) ◽  
pp. 529-535 ◽  
Author(s):  
B. Jarrott ◽  
W. J. Louis
Keyword(s):  
Tyrosine Hydroxylase ◽  
Monoamine Oxidase ◽  
Product Inhibition ◽  
Acid Decarboxylase ◽  
Biochemical Basis ◽  
Catecholamine Synthesis ◽  
Amino Acid Decarboxylase ◽  
Storage Vesicles ◽  
Noradrenaline Synthesis ◽  
Rate Limiting

1. The activities of the enzymes involved in catecholamine synthesis, tyrosine hydroxylase, aromatic amino acid decarboxylase and dopamine β-hydroxylase, were markedly enhanced in homogenates of phaeochromocytoma compared with human adrenal medulla homogenates measured under optimum substrate concentrations. 2. It was demonstrated in fresh tumour slices that the rate of formation of dopamine (3,4-dihydroxyphenethylamine) from tyrosine was much slower than the rate of formation of dopamine from dopa (3,4-dihydroxyphenylalanine) (suggesting that tyrosine hydroxylase was the rate-limiting enzyme in noradrenaline synthesis in phaeochromocytoma) and that the tyrosine hydroxylation step was still susceptible to end-product inhibition by catecholamines. 3. It is suggested that catecholamine overproduction in phaeochromocytoma is due to the increased activities of catecholamine synthetic enzymes rather than to an insensitivity of tyrosine hydroxylase to end-product inhibition. 4. The activities of the enzymes involved in catecholamine catabolism, monoamine oxidase and perhaps catecholamine O-methyltransferase, were reduced in phaeochromocytoma. This finding provides a biochemical basis for the previous published observations of nonexocytotic release of catecholamines in these tumours. Thus excess amounts of newly synthesized noradrenaline which cannot be stored in the filled catecholamine storage vesicles may not be degraded owing to the reduced monoamine oxidase activity and could diffuse from the phaeochromocytoma into the circulation.

Two populations of tyrosine hydroxylase-positive cells occur in the spinal cord of the chick embryo and hatchling

1987 ◽  
Vol 83 (3) ◽  
pp. 253-258 ◽  
Author(s):  
James A. Wallace ◽  
Richard M. Mondragon ◽  
Permelia C. Allgood ◽  
Thomas J. Hoffman ◽  
Rolanda R. Maez
Keyword(s):  
Spinal Cord ◽  
Tyrosine Hydroxylase ◽  
Chick Embryo ◽  
Two Populations

Norepinephrine levels in experimental spinal cord trauma

1977 ◽  
Vol 46 (3) ◽  
pp. 342-349 ◽  
Author(s):  
Stephen E. Rawe ◽  
Robert H. Roth ◽  
Margaret Boadle-Biber ◽  
William F. Collins
Keyword(s):  
Spinal Cord ◽  
Tyrosine Hydroxylase ◽  
Concentration Gradient ◽  
Neurological Function ◽  
Spinal Cord Tissue ◽  
Spinal Cord Trauma ◽  
Content Type ◽  
Spinal Cord Segment ◽  
Fine Print

✓ Levels of norepinephrine (NE) in the spinal cord tissue of nontraumatized cats are highest in the cervical and lumbar enlargements. A rather uniform but slightly increasing concentration gradient from cephalad to caudad is observed in the thoracic segments. A 500 gm-cm trauma at the T-5 or C-7 spinal cord segment did not demonstrate any significant increase in NE levels measured sequentially over a 4-hour period after trauma. Dopamine levels could not be detected in the nontraumatized or traumatized cat spinal cords. Four traumatized cats treated with alpha methyl tyrosine, a tyrosine hydroxylase inhibitor, and followed clinically for 5 months showed no improvement in neurological function when compared to untreated traumatized cats. This study does not support the norepinephrine hypothesis of experimental spinal cord trauma.

scholarly journals Enhancement of rat brain catecholamine synthesis by administration of small doses of tyrosine and evidence for substrate inhibition of tyrosine hydroxylase activity by large doses of the amino acid

1982 ◽  
Vol 206 (1) ◽  
pp. 165-168 ◽  
Author(s):  
Abdulla A.-B. Badawy ◽  
David L. Williams
Keyword(s):  
Amino Acid ◽  
Tyrosine Hydroxylase ◽  
Rat Brain ◽  
Substrate Inhibition ◽  
Hydroxylase Activity ◽  
Catecholamine Synthesis ◽  
Tyrosine Hydroxylase Activity ◽  
Small Doses

Rat brain catecholamine synthesis is enhanced by small doses of tyrosine, but not by doses of 50mg/kg body wt. and above. It is suggested that these latter doses overcome the above enhancement by causing a substrate inhibition of tyrosine hydroxylase activity.

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