Catecholamine, and histamine

M. Carman-Kizan. Endothelial catecholamine and histamine receptors. Jug. PhysiaL Pharmacol, Acta 25 19-20 (1989). 

A less costly alternative to fluorescamine is o-phthaldehyde (OPT), the derivatives of which are more stable and consequently can be stored overnight if necessary. It is used in a similar manner to fluorescamine the detection limits being about 0.1 ng ca. 4 x g/ml). OPT has been used in the analysis of dopamine, catecholamines and histamines. Other fluorescence reagents that are sometimes used include 4-bromoethyl-7-methoxycoumarin, diphenylindene, sulphonyl chloride, dansyl-hydrazine and a number of fluorescent isocyanates. 

Note The pre- and post-treatment of the chromatograms with the basic tri-ethylamine solution, which can be replaced by an alcoholic solution of sodium hydroxide [1,4] or a phosphate buffer solution pH = 8.0 (c = 0.2 mol/1) [5], serves to stabilize the fluorescence of the amino derivatives [2]. A final spraying with methanolic hydrochloric acid (chci = 5 mol/1) or 70% perchloric acid renders the detection reaction highly specific for histamine [4] and for catecholamines and indolamines [5]. 

The derivatives have an optimum fluorescence at an excitation wavelength of 340 nm and an emission wavelength of 455 nm. The adduct is relatively stable at a pH of 9-11 but it rapidly degrades to a non-fluorescent residue at low pH values. Consequently, when used as a pre-column derivatizing reagent the pH of the mobile phase should be kept fairly high, o-phthalaldehyde has been employed for derivatization in the analysis of dopamine (29), catecholamines (30) and histamines (31). 

Unlike catecholamines and indoleamines, histamine itself is not a direct inhibitor of its biosynthetic enzyme, but it exerts feedback control through the H3 autoreceptor. Perhaps the most powerful tool in the study of the histamine system is S-a-fluoromethylhistidine, a highly selective and potent suicide inhibitor of HDC [22]. This compound has been used successfully to study many of the functions of histamine in brain. 

Biogenic amines arise from amino acids by decarboxylation (see p. 62). This group includes 4-aminobutyrate (y-aminobutyric acid, GABA), which is formed from glutamate and is the most important inhibitory transmitter in the CNS. The catecholamines norepinephrine and epinephrine (see B), serotonin, which is derived from tryptophan, and histamine also belong to the biogenic amine group. All of them additionally act as hormones or mediators (see p. 380). 

The methyl transferases (MTs) catalyze the methyl conjugation of a number of small molecules, such as drugs, hormones, and neurotransmitters, but they are also responsible for the methylation of such macromolecules as proteins, RNA, and DNA. A representative reaction of this type is shown in Figure 4.1. Most of the MTs use S-adenosyl-L-methionine (SAM) as the methyl donor, and this compound is now being used as a dietary supplement for the treatment of various conditions. Methylations typically occur at oxygen, nitrogen, or sulfur atoms on a molecule. For example, catechol-O-methyltransferase (COMT) is responsible for the biotransformation of catecholamine neurotransmitters such as dopamine and norepinephrine. A-methylation is a well established pathway for the metabolism of neurotransmitters, such as conversion of norepinephrine to epinephrine and methylation of nicotinamide and histamine. Possibly the most clinically relevant example of MT activity involves 5-methylation by the enzyme thiopurine me thy Itransf erase (TPMT). Patients who are low or lacking in TPMT (i.e., are polymorphic) are at... 

Tubular secretion The active secretory systems can rapidly remove the protein-bound drugs from the blood and transport them into tubular fluid as the drugs that are bound to proteins are not readily available for excretion by filtration. The drugs known to be secreted by organic anion secretory system (i.e. strong acids) are salicylates, chlorothiazide, probenecid, penicillin etc. and cation (i.e. bases) includes catecholamines, choline, histamine, hexamethonium, morphine etc. 

MODULATION OF CATECHOLAMINES AND SEROTONIN RELEASE MEDIATED BY HISTAMINE H3 HETERORECEPTORS... 

There are two enzymes capable of metabolizing catecholamines. The first is monoamine oxidase (MAO), a mitochondrial enzyme that oxidatively deaminates catecholamines, tyramine, serotonin, and histamine. MAO is further subclassified as either monoamine oxidase A, which metabolizes norepinephrine and is inhibited by tranylcypromine, and monoamine oxidase B, which metabolizes dopamine and is inhibited by 1-deprenyl. Catechol-O-methyltransferase (COMT), a soluble enzyme present mainly in the liver and kidney, is also found in postsynaptic neuronal elements. About 15% of norepinephrine is metabolized postsynaptically by COMT. 

Endogenous biogenic amines in the brain include catecholamines [NE (noradrenaline, NA), dopamine (DA), epinephrine (adrenaline)] 5-HT, histamine, and the so-called trace amines (P-phenylethylamine, tyramine, tryptamine, and octopamine). These amines have in common a arylalkylamine stmcture, and all have been implicated in the etiology of one or more psychiatric disorders and/or in therapeutic and/or adverse effects of drugs used to treat such disorders. In this review on depression, the focus in the case of biogenic amines will be on 5-HT, NE, and DA, although epinephrine and histamine and trace amines have also been implicated (see the section on Other Antidepressant Approaches and Targets ). 

Fluoxetine has been found to cause selective central nervous system (CNS) neuronal uptake inhibition of serotonin. While fluoxetine may bind to adrenergic, muscarinic, and histaminic receptors, it has not been shown to have the profound effects on catecholamines that are common to tricyclic antidepressant overdose patients. 

Catecholamines and amines of the histamine and tryptophan group are highly polar compounds and hence have low volatility. It is preferable, as is the case with amino acids, q.v., therefore, to form derivatives to obtain satisfactory gas-liquid chromatograms. The main problem in the analysis of urine for these amines lies not in the gas chromatographic aspect of the procedure, but rather in their isolation from the urine prior to GLC, where there may be as little as 1 /tg of amine per 100 ml of urine. It appears that this problem of extracting the amines into a sufficiently small volume of suitable solvent prior to GLC has not yet been solved satisfactorily. The fact that GLC can be used successfully to separate catecholamines through their derivatives when starting with pure substances should provide a stimulus for increased research activity in this field. 

Histamine may be used diagnostically to identify patients with pheochromocytoma (it increases the release of catecholamines) and to distinguish pernicious anemia (a lack of acid release indicates achlorhydria). 

There are two enzymes capable of metabolizing catecholamines. The first is monoamine oxidase (MAO), a mitochondrial enzyme that oxidatively deaminates catecholamines, tyramine, serotonin, and histamine. MAO is further subclassified... 

Methylation is an important reaction in the biosynthesis of endogenous compounds such as adrenaline and melatonin, in the inactivation of biogenic amines such as the catecholamines, serotonine and histamine, and in modulating the activities of macromolecules, such as proteins and nucleic acids. The number of xenobiotics that are methylated is comparatively modest, yet this reaction is seldom devoid of pharmacodynamic consequences (toxication or detoxication). Reactions of methylation imply the transfer of a methyl group from the onium-type cofactor S-adeno-sylmethionine (SAM) to the substrate by means of a methyltransferase. The activated methyl group from SAM is transferred to the acceptor molecules R — XH or RX, as shown in Fig. 31.30. 

In addition to more or less complete amino acid separations, suitable chromatographic systems for the rapid determination of selected amino acids [4-amino-butyric acid (GABA) [336], histidine and 3-methylhisti-dine [367] or a group of selected amino acids, such as those involved in the urea cycle (arginine, citrulline, ornithine, agmatine) [368], have been reported. Precolumn derivative formation with OPA/R-SH reagents is also suited to the automated establishment of peptide maps [369]. A number of authors have published methods for the sensitive determination of aminoglycoside antibiotics [365,370—373]. The method has also found application for the determination of histamine and its methylation products [374—376], catecholamines and serotonin [377—379] and polyamines [380]. 

Several of these amines are found in animals and some are involved in nerve transmission see Chapter 27). When plant amines are consumed by animals, they can be quite toxic. For example, phenylethylamine (8) in Acacia berlan-dieri is poisonous to livestock (Smith, 1977b). The presence of amines in foods consumed by humans also has been noted. Catecholamines, indoleamines, and histamine (11) fulfill important metabolic functions, especially in the nervous system and in the control of blood pressure. The occasional presence of greater than usual amounts of tyramine in cheese can cause severe episodes of hypertension, especially in the presence of monoamine oxidase inhibitors, which often are used in the treatment of depression (Smith, 1981). Amines can be formed from bacterial activity in foods (Smith, 1981). 

Melmon, K. L., 1981, The endocrinologic function of selected autacoids Catecholamines, acetylcholine, serotonin, and histamine, in Textbook of Endocrinology (R. H. Williams, ed.), pp. 514-588, W. B. Saunders, Philadelphia. 

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