Norepinephrine acetates

Synthetic chemical approaches to the preparation of carbon-14 labeled materials iavolve a number of basic building blocks prepared from barium [ CJ-carbonate (2). These are carbon [ C]-dioxide [ CJ-acetjlene [U— C]-ben2ene, where U = uniformly labeled [1- and 2- C]-sodium acetate, [ C]-methyl iodide, [ C]-methanol, sodium [ C]-cyanide, and [ CJ-urea. Many compHcated radiotracers are synthesized from these materials. Some examples are [l- C]-8,ll,14-eicosatrienoic acid [3435-80-1] inoxn. [ CJ-carbon dioxide, [ting-U— C]-phenyhsothiocyanate [77590-93-3] ftom [ " CJ-acetjlene, [7- " C]-norepinephrine [18155-53-8] from [l- " C]-acetic acid, [4- " C]-cholesterol [1976-77-8] from [ " CJ-methyl iodide, [l- " C]-glucose [4005-41-8] from sodium [ " C]-cyanide, and [2- " C]-uracil [626-07-3] [27017-27-2] from [ " C]-urea. All syntheses of the basic radioactive building blocks have been described (4). 

The solubility of the resulting product may dictate the choice of solvent. Reductive alkylation of norepinephrine with a series of keto acids proceeded smoothly over platinum oxide in methanol-acetic acid mixtures. However, when n = 4 or 5, the product tended to precipitate from solution, making catalyst separation difficult. The problem was circumvented by using glacial acetic acid as solvent 38). 

FIGURE 3-27 Three-dimensional chromatogram for oxidizable biological compounds at a multichannel amperometric detection system, consisting of an array of 16 carbon-paste electrodes held at different potentials. AA = ascorbic acid NE = norepinephrine DOPAC = 3,4-dihydroxyphenylacetic acid 5-HIAA = 5-hydroxyindole-3-acetic acid DA = dopamine HVA = homovanillic acid. (Reproduced with permission from reference 68.)... 

Figure 2 Selective electrochemical detection of a mixture on multielectrode amper-ometry. AA = Ascorbic acid, NE = norepinephrine, DOPAC = 3-4-dihydroxy-phenylacetic acid, E = epinephrine bitartrate, 5-HIAA = 5-hydroxyindole-3-acetic acid, HVA = homovanillic acid, TRP = tryptophan, 5-HT = 5-hydroxytryptamine, and 3-MT = 3-methoxytyramine (separated by RPLC). Detection was with a 4-electrode glassy carbon array, with electrode 1 at 500 m V) electrode 2 at 700 mV, electrode 3 at 900 mV, and electrode 4 at 1100 mV. Note that at electrode 1, HVA, TRP, and 3-MT are not seen. At electrode 2, only TRP is not seen. A standard calomel electrode was used as reference. (Reprinted with permission from Hoogvliet, J. C., Reijn, J. M., and van Bennekom, W. P., Anal. Chem., 63, 2418, 1991. 1991 Analytical Chemistry.)...

The primary mechanism used by cholinergic synapses is enzymatic degradation. Acetylcholinesterase hydrolyzes acetylcholine to its components choline and acetate it is one of the fastest acting enzymes in the body and acetylcholine removal occurs in less than 1 msec. The most important mechanism for removal of norepinephrine from the neuroeffector junction is the reuptake of this neurotransmitter into the sympathetic neuron that released it. Norepinephrine may then be metabolized intraneuronally by monoamine oxidase (MAO). The circulating catecholamines — epinephrine and norepinephrine — are inactivated by catechol-O-methyltransferase (COMT) in the liver. 

Figure 4-3 shows the influence of organic modifiers on the voltammogram of norepinephrine (nor) in different solvents A, B and C (the dashed lines show the oxidation of the solvents). Solvent A water, 0.02 M sodium acetate B methanol, 0.02 M sodium acetate C acetone/water 90/10, 0.02 M ammonium perchlorate. Solvents A, B and C pH 7, 0.005 M NaCl. 

Also, harmala alkaloids create effects on monoamine turnover. Postnatal rats administered harmaline (shortly before birth) have elevations in brain levels of the norepinephrine metabolite 3-methoxy-4-hydroxy-phenylglycol (MHPG), but decreases in the dopamine and serotonin metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindole acetic acid (5-HIAA) (Okonmah et al. 

Morier-Teissier et al. [156] determined that administration of EGb altos the levels of catecholamines, indolamines and their metabolites in some brain areas of young rats and mice. Marked changes in the EGb-treated brain were found for norepinephrine, 5-HT, and its metabolite, 5-hydroxyindole-3-acetic add, whereas it was less effective for dopamine and its metabolite 3,4-dihydroxy-phenylaoetic add. EGb-induced changes depend on the route of administration (p.o. or L p.), dose and duration of treatment (acute or chronic). 

TLC separation of DNS-amines is usually made on layers of silica gel with solvents covering a range of polarity, e.g., chloroform, ethyl acetate, diisopropyl ether and methanol. Seiler and Wiechmann [97] developed 30 solvent systems for the separation of DNS derivatives of over 100 biogenic amines on TLC plates of silica gel. The selective reaction of DNS-C1 with the amino group of catecholamines has been examined [98]. The drugs dopamine, norepinephrine and epinephrine are adsorbed on alumina which protects their hydroxyl groups from dansylation. The N-dansylated compounds are separated with benzene-dioxane-acetic acid (90 25 4) on layers of silica gel. 

List of Abbreviations Ach, acetylcholine AMPA, a-amino-3-hydroxy-5-methylisoxazole-4-propionic acid CNS, central nervous system COMT, catechol-O-methyltransferase DA, dopamine DRP-2, dihy-dropyrimidinase-related protein 2 DSM, diagnostic and statistical manual of mental disorders GNAS1, guanine nucleotide-binding protein (G-protein) alpha stimulating activity polypeptide 1 5-HIAA, 5-hydroxyindole acetic acid 5-FIT, serotonin (5-hydroxytryptamine) MAO, monoamine oxidase MHPG, 3-methoxy-4-hydroxyphenylglycol NE, norepinephrine NMDA, N-methyl-D-aspartate PCP, phencyclidine SSRI, selective serotonin reuptake inhibitor SDS, schedule for the deficit syndrome... 

In one, S-adenosyl-L-methionine was the methyl donor, norepinephrine was the substrate, while products of the reaction, normeranephrine and norparanephrine, were converted to the more stable and more easily obtained compounds vanillin and isovanillin, respectively, by periodate oxidation. The oxidation also allowed for the extraction of the incubation mixture with organic solvents such as ethyl acetate, affording a more complete deproteinization. 

Disposition - It is possible that one mechanism for the disposition of the endogenously produced amine is by diffusion, which could be followed by re-uptake by nerve endings (or by other material in tissues) as has been shown with norepinephrine. But as yet there is no evidence for such a cycle for HT, although, as noted above, brain and its particulate fractions have the capacity for uptake. A main catabolic pathway for HT is oxidative deamination by monoamine oxidase to form 5-hy-droxyindoleacetaldehyde, most of which is converted to 5-hydroxyindole-acetic acid (HIAA) by aldehyde dehydrogenase and NAD S, 56 relatively small portion is reduced to 5-hydroxytryptophol by alcohol dehydrogenase and NADH " Monoamine oxidase, which, like... 

Since L-tyrosine is the main precursor of melanins and a substrate of tyrosinase, the L-DOPA/L-tyrosine ratio could more accurately reflect tyrosinase activity than l-DOPA alone. In 1997, we developed two reversed-phase HPLC techniques, one with electrochemical detection to measure simultaneously l-DOPA, norepinephrine (NE), epinephrine (E), dopamine (DA), and DOPAC (3,4-dihydroxyphenyl acetic acid) (all compounds easily oxidizable between +0.15 and +0.50 V), and one with fluorimetric detection to measure L-tyrosine (and phenylalanine) on the same blood sample. 

Fig. 4.4.12. Separation of a mixture of acidic and basic catecholamines on a LiChrosorb RP-8 column (0.28x25 cm). Eluent Water containing 0.02 M citrate (pH 2.5)/l% propanol/NaCIQ4 (0.08 M)/0.3% sodium dodecyl sulphate. Peaks DHMA, 3,4-dihydroxymandelic acid VMA, vanilmandelic acid HGA, 2,5-dihydroxyphenylacetic acid DOPAC, 3,4-dihydroxyphenylacetic acid 5-HIAA, 5-hydroxyindole-3-acetic acid HVA, homovanillylmandelic acid E, epinephrine NE, norepinephrine N-Syn, norsyneph-rine Syn, synephrine Dopa, 3,4-dihydroxyphenylalanine NM, normetanephrine MN, metanephrine Isopren, isoprenaline 3-H-Tyrm, dopamine Tyrm, tyramine 3-M-Tyrm, 3-methoxytyramine. Reprinted from Ref. 21 with permission.

Norepinephrine reduction can be due to a severe cell loss in LC of AD brains. Serotonin, its metabolite 5-hydroxyindole-3-acetic acid and norepinephrine are measured to be decreased in hippocampal formation. The substantia innominata may be unaffected (Baker and Reynolds, 1989). The loss of serotonin correlates to many neuropathological findings in serotonergic cells of the nuclei raphe (Quirion et al., 1986). 

Hydroxy"5-methoxytryptamine produces an increase in exploratory behavior in animals, but not significant from controls. No effect on serotonin norepinephrine brief decrease in 5-hydroxyindole acetic acid (5-HIAA). (Maickei 1978)... 

Figure 6-2. Characteristics of transmitter synthesis, storage, release, and termination of action at cholinergic and noradrenergic nerve terminals are shown from the top downward. Circles represent transporters ACh. acetylcholine AChE. acetylcholinesterase ChAT, choline acetate transferase DOPA, dihydroxyphenylalanine NE, norepinephrine TCA, tricyclic antidepressant TH, tyrosine hydroxylase.

Fig. 1 Chromatograms of a standard solution of monoamine transmitters and their metabolites at (A) a poly(para-aminobenzoic acid) modified electrode and (B) a bare glassy carbon electrode. (1) Norepinephrine, (2) epinephrine, (3) dopamine, (4) 3,4-dihydroxyphenol acetic acid, (5) serotonin, (6) 5-hydroxyindole acetic acid, and (7) homovanillic acid. Source From Study on the effect of electromagnetic impulse on neurotransmitter metabolism in nerve cells by high performance liquid chromatography-electrochemical detection coupled with microdialysis, in Anal. Biochem. ...

Fig. 9. Norepinephrine and dopamine release from brain slices (slices of rat nucleus accumbens). (A) Dopamine standard (10 pmol injected onto column—volume 100 pi) (B) norepinephrine standard (10 pmol injected onto column—volume 100 pi) (C) supernatant obtained after incubation of one sliced nucleus accumbens in Krebs buffer containing pargyline (10 M) at 37°C for 10 min, followed by centrifugation (Bennett et ai, 1981fl). The supernatant is deproteinized by addition of 20 pi 0.1 M perchloric acid per 2 ml supernatant and then centrifuged, and 100 pi is injected onto the column. Note the small norepinephrine and large dopamine peaks (D) same as C, except the nucleus accumbens (the other accumbens from the same animal as in G) was incubated in the presence of d-amphetamine (10 M). Note the increased norepinephrine and dopamine peaks. Chromatographic conditions column, cation-exchange Nucleosil (10 p) 30 cm X 2.1 mm mobile phase, 0.05 M acetate/citrate, pH 4.8 flow rate, 1.2 ml/min electrode potential, +0.65 V sensitivity, 2 nA/V full scale deflection volume injected, 100 pi.

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