Catecholamines adrenal medullary

Tyrosine hydroxylase and dopamine- -hydroxylase occur only in those cells which synthesize catecholamines (adrenal medullary cells and adrenergic neurons). When the sympathetic innervation of peripheral organs is destroyed (surgically, immunologically or chemically) these enzyme activities disappear. This is not true of DOPA decarboxylase, which occurs in many cells apart from those involved in catecholamine biosynthesis. This enzyme, for example, is also found in S-hydroxy-tryptamine-containing cells, and in the kidney, liver and certain glial cells associated with cerebral blood vessels. 

Deficiency of adrenal medullary catecholamines appears to give no ill effects, and replacement therapy is therefore not used, but adrenal medullary tumours, phaeochromocytomas, secrete excess catecholamines often causing hypertension with dramatic episodes of headache, palpitations, pallor, sweating and anxiety. This condition is normally treated surgically, but preoperative preparation is mandatory to avoid catastrophic effects of surges of catecholamine release. A combination of alpha- and beta-adrenergic receptor blockade is normally used, with drugs such as phenoxybenzamine or doxazosin as alpha-blockers, and propranolol as a non-selective beta-blocker. 

Liu M, Yanagihara N, Toyohira Y, Tsutsui M, Ueno S, Shinohara Y. 2007c. Dual effects of daidzein, a soy isoflavone, on catecholamine synthesis and secretion in cultured bovine adrenal medullary cells. Endocrinology 148 5348-5354. 

Chang, H.-T. Yeung, E.S. Determination of catecholamines in single adrenal medullary cells by capillary elec-... 

Ahnert-Hilger G, Bader MF, BhakDai S et al. (1989b) Introduction of macromolecules into bovine adrenal medullary chromaffin cells and rat pheochromocy-toma cells (PC12) by permeabilization with streptolysin O inhibitory effect of tetanus toxin on catecholamine secretion. J. Neurochem. 52 1751 -8... 

Mescaline causes hallucinogenic effects by stimulating serotonin and dopamine receptors in the central nervous system. The sympathomimetic effects of mescaline are probably also centrally mediated. Changes in catecholamine metabolism and adrenal medullary function may be responsible for the agent s... 

Catechol-0-methyltransferase (COMT) is responsible for the second major pathway of catecholamine metabolism, catalyzing 0-methylation of dopamine to methoxytyramine, norepinephrine to normetanephrine, and epinephrine to metanephrine. COMT is not present in monoamine-producing neurons, which contain exclusively MAO, but is present along with MAO in most extraneuronal tissue. The membrane-bound isoform of COMT, which has high affinity for catecholamines, is especially abundant in adrenal chromaffin cells. As a result of the preceding and other differences in the expression of metabolizing enzymes, catecholamines produced at neuronal and adrenal medullary locations follow different neuronal and extraneuronal pathways of metabolism (Figure 29-5). 

A characteristic feature of adrenal medullary chromaffin cells is the presence of numerous catecholamine storage granules ranging in size from 100 to 300 nm in diameter. These granules turn brown when exposed to potassium bichromate solutions, ammoniacal silver nitrate, or osmium tetroxide because of the oxidation and polymerization of epinephrine and norepinephrine. This process is known as the chromaffin reaction, hence the terms chromaffin cells and chromaffin granules. At least two kinds of adrenal medullary chromaffin cells have been identified in most animal species based on differences in chromaffin granules. Norepinephrine-producing chromaffin cells possess dense-... 

Sympathetic Nervous Function, Disorders of Adrenal Medullary Function, and Genetic Disorders of Catecholamine Systems... 

Familial dysautonomia, dopamine [i-liydroxylase deficiency, norepinephrine transporter deficiency, and congenital adrenal hyperplasia include dysautonomias or conditions associated with adrenal medullary dysfunction in which the specific genetic abnormalities have been identified. There are also other disorders involving mutations of genes coding for proteins involved in catecholamine synthesis and metabolism in which the clinical manifestations do not clearly involve the sympathoadrenal systems or may be so globally severe that abnormalities of autonomic or adrenal medullary function are obscured (Table 29-5). 

Adrenal medullary cells have plasma membrane receptors for acetylcholine (ACh) of the neuronal nicotinic subtype (Nn). These receptors are cation channels that span the plasma membrane and are activated by ACh to rapidly increase Na" " and K+ permeabilities (Na" " influx rate 5 x 10 ions/s), causing the cells to depolarize and release their catecholamines by exocytosis. The cholinergic stimulation of exocytosis is accompanied by an activation of tyrosine hydroxylase activity within the adrenal medullary cell, and this promotes biosynthesis of... 

The role of the catecholamines, adrenaline, and noradrenaline, in the fight or flight response is well known and the possible connection between enhanced sympathetic and adrenal medullary activity and the vascular changes, tachycardia and early hyperglycemia after injury is apparent. An increased urinary excretion of catecholamines is known to occur for several days following injury (C16, G13). Analysis of adrenal vein blood has shown that anesthesia, hemorrhage, and injury can all stimulate adrenaline production (W5). 

It is perhaps a little surprising that improved analytical methods (e.g., high-performance liquid chromatography, proton resonance mass spectrometry) have not led to a reexamination of catecholamines as markers of stress and adrenal medullary function. 

Two major neuro-endocrine systems have been associated with stress. The first one is associated with acute stressful states such as fear, anger and excitement (Amkraut and Solomon 1975) and is called the sympathetic-adrenal-medullary system (SAM). SAM activation has been associated with action proneness and raised effort and it has also been described as the fight or flight system . It is activated when the organism is challenged in its control of the environment, and is accompanied by the release of catecholamines (epinephrine and norepinephrine) into the bloodstream. Catecholamine output is increased in response to a challenge to perform well (Frankenhaeuser et al. 1980 Lundberg and Frankenhaeuser 1980). 

The sympathetic adrenal medullary (SAM) system with the secretion of the catecholamines epinephrine and norepinephrine (or adrenaline and noradrenaline) has been of particular interest in the study of stress. 

Fig. 8 Amperometric detection at isolated bovine adrenal medullary cells detected at glass encased (a—c) and etched (d-f) carbon fiber electrodes at 1 (A, D), 5 (B, E) and 10 pm (C, F). Measurements at each position were made simultaneously with the large and small electrode. Release of catecholamines was induced by a 3-s, 100-pM nicotine exposure applied at 1.25 s. (Reproduced with the permission of the American Chemical Society from K. T. Kawagoe, J. A. Jankowski,...

Secretion is another Ca mediated cellular activation process sharing many points in common with muscular contractility We have verified that a specific monovalent ionophore, salinomycin, does in fact cause a multifold augmentation of plasma catecholamines in animals . In addition, monensin causes a release of catecholamines from cultured adrenal medullary chromaffin These obser-... 

The egg-white anaphylactoid reaction is accompanied by haemoconcentration and hypothermia [243, 247, 248], both of which are probably a consequence of the increased vascular permeability and oedema of the Reaction. The adrenal cholesterol, circulating eosinophil count and blood concentration of corticosteroids remain unchanged after egg-white is administered to rats. The adrenal ascorbic acid, however, is significantly decreased, but this does not correlate with the severity of the anaphylactoid oedema [641, 642]. Other studies show that there is a reduction of the adrenal medullary catecholamines during the egg-white reaction and these amines may condition the resistance of the rats to the effects of egg-white [392]. 

The utility of this dual microsensor has been tested at bovine adrenal medullary cells [45] however, the technique has the potential to be used at other cultured cell types, including PC 12 cells. The sensor has a subsecond response time for both Ca + and catecholamine concentration changes, and Ca + concentrations as low as 100 nM can be detected while the detection limit for catecholamine is in the micromolar range. 

PS Cahill, RM Wightman. Simultaneous amperometric measurement of ascorbate and catecholamine secretion from individual bovine adrenal medullary cells. Anal Chem 67 2599-2605, 1995. 

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