Browsing by Subject "Catecholamines"

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    Distribution of central catecholaminergic neurons, a comparison between ungulates, humans and other species
    (Murcia : F. Hernández, 1998) Tillet, Y.; Kitahama, K.
    In ungulates and primates, the distribution of central catecholaminergic neurons identified using antibodies raised against catecholamine synthesizing enzymes and catecholamines themselves, shows many differences if compared to rats. Catecholaminergic neurons are more loosely clustered in ungulates and primates than in rat. In the medulla oblongata, the density of noradrenergicladrenergic neurons is lower in ungulates than in other species and, particularly in sheep, the adrenergic group C1 is not observed. The noradrenergic neurons of the locus coeruleus are present in a larger area in ungulates than in rodents. In the hypothalamus, the density of dopamine neurons is lower in ungulates and primates than in rodents. In the rostra1 hypothalamus of ungulates, the dorsal part of the group A14 is missing, and these species present only the ventral part of the group A15. In primates the group A15 extends into the supraoptic and paraventricular nuclei which have large tyrosine hydroxylase-immunoreactive (TH-IR) neurons not observed in other species. In addition, in all studied species, not all cells expressing catecholamine synthesizing enzymes also express catecholamines, as found in some TH-IR neurons in the arcuate nucleus, thereby demonstrating the necessity of using different markers to ascertain the true catecholaminergic nature of labeled neurons. These anatomical differences between species show the difficulty in extrapolating the distribution of catecholamine neurons from one species to another and may be related to adaptative physiological differences between mammals.
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    Is hematopoiesis under the influence of neural and neuroendocrine mechanisms?
    (Murcia : F. Hernández, 1998) Maestroni, G.J.M.
    It is well recognized that the immune response is under the influence of a variety of neural or neuroendocrine mechanisms. Much less studied is the possible influence of these mechanisms on hematopoiesis. Here I review the existing evidence about a neural andlor neuroendocrine regulation of hematopoiesis. The physiology of the blood forming system seems to be controlled at three levels, i.e. at the cellular level by the bone marrow stroma, at the humoral level by hematopoietic cytokines and finally by catecholamines and neuroendocrine factors. Bone marrow catecholarnines originate from sympathetic nerve fibers and from hematopoietic cells directly. Catecholamines of neural origin show a circadian rhythmicity. Adrenoceptors present on bone marrow cells include the a l - subtype which seems to mediate the catecholaminergic control of hematopoiesis. Neuroendocrine factors including substance P, neurokinin-A and the pineal hormone melatonin might also influence hematopoiesis by affecting hernatopoietic cytokines. In particular, melatonin seems to affect hematopoiesis via the induction in bone marrow T-helper cells of two novel opioid cytokines. A complete understanding of the neural and neuroendocrine regulation of hematopoiesis might provide new conceptual and therapeutic perspectives in a variety of hematopoietic and immune diseases.
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    Kinetic characterization of the oxidation of catecolamines and related compounds by laccase
    (Elsevier, 2020-07-25) Taboada Rodriguez, Amaury; Manzano Nicolás, Jesús; Teruel Puche, José Antonio; Marín Iniesta, Fulgencio; García Cánovas, Francisco; García Molina, Francisco; Tudela Serrano, José; Muñoz Muñoz, José Luis; Bioquímica y Biología Molecular A
    The pathways of melanization and sclerotization of the cuticle in insects are carried out by the action of laccases on dopamine and related compounds. In this work, the laccase action of Trametes versicolor (TvL) on catecholamines and related compounds has been kinetically characterized. Among them, dopamine, l-dopa, l-epinephrine, l-norepinephrine, dl-isoprenaline, l-isoprenaline, dl-α-methyldopa, l-α-methyldopa and l-dopa methylester. A chronometric method has been used, which is based on measuring the lag period necessary to consume a small amount of ascorbic acid, added to the reaction medium. The use of TvL has allowed docking studies of these molecules to be carried out at the active site of this enzyme. The hydrogen bridge interaction between the hydroxyl oxygen at C-4 with His-458, and with the acid group of Asp-206, would make it possible to transfer the electron to the T1 Cu-(II) copper centre of the enzyme. Furthermore, Phe-265 would facilitate the adaptation of the substrate to the enzyme through Π-Π interactions. To kinetically characterize these compounds, we need to take into consideration that, excluding l-dopa, l-α-methyldopa and dl-α-methyldopa, all compounds are in hydrochloride form. Because of this, first we need to kinetically characterize the inhibition by chloride and, after that, calculate the kinetic parameters KM and VmaxS. From the kinetic data obtained, it appears that the best substrate is dopamine. The presence of an isopropyl group bound to nitrogen (isoprenaline) makes it especially difficult to catalyse. The formation of the ester (l-dopa methyl ester) practically does not affect catalysis. The addition of a methyl group (α-methyl dopa) increases the rate but decreases the affinity for catalysis. l-Epinephrine and l-norepinephrine have an affinity similar to isoprenaline, but faster catalysis, probably due to the greater nucleophilic power of their phenolic hydroxyl.