Browsing by Subject "Chromaffin cells"

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    Comparison of chromaffin cells from several animal sources for their use as an in vitro model to study the mechanism of organophosphorous toxicity
    (Elsevier, 2006-04-28) Quesada, E.; Sogorb, M. A.; Vilanova, E.; Carrera, V.; García Fernández, Antonio Juan; Romero García, Diego; Ciencias Sociosanitarias
    It had been observed that the chromaffin cells of bovine adrenal medulla contain high levels of neuropathy target esterase (NTE), the esterase whose inhibition and aging is associated with induction of the organophosphorous induced delayed neuropathy. In this study, total esterase and NTE activities, and their inhibition kinetics by OPs are characterized in adrenal medulla of several species in order to find the best source for chromaffin cells. Total esterase activity in membrane fraction of bovine, equine, porcine, ovine and caprine were 6100±840, 4200±270, 5000±120, 28800±3000, and 10800±2400 mU/g tissue, respectively (mean±S.D., n = 3–4). NTE represented around 70%, 24%, 58%, 10% and 24% of the total esterases in the same tissues, respectively. It was deduced that NTE represents between 69% and 89% of the “B-activity” (activity resistant to 40 M paraoxon) in the membrane fraction of all species. The mipafox I50 calculated for 30-min inhibition of NTE at 37 ◦C ranged between 7.4 and 12 M. These values are in the range of that for brain NTE in hen (the usual model for testing OP delayed neurotoxicity). Considering that bovine adrenal medulla contains high NTE activity, that it represents a high proportion of total activity, it is easier to dissect than adrenal medulla from equine, caprine or ovine, and is more readily available than species cited previously, and that its inhibitory properties are similar to the classical hen brain model, it is deduced that bovine adrenal medulla is the most appropriate source of chromaffin cells to study OP toxicity, with porcine as the second alternative. The kinetic properties of chromaffin cell cultures from bovine and porcine were in accordance with their properties in homogenate and subcellular fractions, and they displayed an appropriate stability and viability of the primary culture to be used in in vitro toxicological studies for both mechanistic and testing purposes.
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    Expression of a neu,c-erbB-2-like product in neuroendocrine cells of mammals
    (Murcia : F. Hernández, 2000) Martin Lacave, Inés; Utrilla, J.C.
    The neulc-erbB-2 oncogen encodes a 185 kDa protein closely homologous to the epidermal growth factor receptor. The protein product (p185) is a glycoprotein with an external domain and an internal domain with tyrosine kinase activity. Amplification and/or overexpression of p185 is related to several human adenocarcinomas. Subsequent studies demonstrated its presence in certain neuroendocrine (NE) neoplasms, including phaeochromocytomas. insulinomas and medullary thyroid carcinomas. However, relatively little is known about its role in normal cell growth regulation and development. Therefore, our objetive was to determine whether neulc-erbB-2 was expressed in normal NE tissues of different mammals, specially in humans, as it was in their neoplasms. We have examined by immunohistochemistry different endocrine glands (thyroid, pancreas, suprarrenal and hypophysis) and the small intestine of human beings, rats and guinea pigs, using two polyclonal antibodies raised against the intracytoplasmic part of the protein, and specific antigen absorption controls. We have found that a neulc-erbB-2- like product occurs in all normal NE tissues examined: C cells of the thyroid gland, chromaffin cells of the adrenal medulla, pancreatic islets, enteroendocrine cells of the small intestine and, finally, scattered cells of the adenohypophysis, according to a typical granular immunohistochemical pattern. Our results indicate that normal NE cells share a new common antigen in their cytoplasms, a neulc-erbB-2-like product, with a similar immunostaining pattern to that presented by the neoplasms derived from them.
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    Paracrine control of steroid hormone secretion by chromaffin cells in the adrenal gland of lower vertebrates
    (F. Hernández y Juan F. Madrid. Universidad de Murcia. Departamento de Biología Celular e Histología, 1998) Mazzocchi, G.; Gottardo, G.; Nussdorfer, G. G.
    The adrenal glands of lowe r vertebrates display a notable intermingling between steroidogenic and chromaffin tissues, which increases from Pisces to Al'es. As in mammals, adrenal chromaffin cells contain and release, in addition to catechol amines, serotonin and several peptides, which may affect the secretory acti vity of steroidogeni c cells in a paracrine manner. Stimulatory molec ul es in c lud e se roto nin , arg inin e-va so tocin. tachykinin s, vasoac ti ve intestinal peptide , pituita ry adenylate cyclase-acti vating peptide and calcitonin generelated peptide: inhibitory molec ul es are dopamine, somatotropic hormone-release inhibiting hormone and ga lanin . Epin ephrine and no repinephrine appe ar to stimulate steroid sec retion in Aves and to inhibit it in Pisces, while their ac tion in Amphibia is controversial. Likewise . atri a l natriureti c peptide exe rts an antisec re ta gog ue ac ti o n in Amphibia and a ma rk ed secretagogue effe ct in Pisces and Aves. The effects of opioids (enkephalins and endorphins) have scarcely been in vesti ga ted a nd th e findin gs obt a ined a re hi g hly qu esti o nabl e. Compared with the ama zin g ma ss of in vestigations carried out in mammals, studies in lower ve rtebrates a re few, and in large part pe rformed in Amphibia and Al'es. It appears that much further work has to be done by comparati ve endocrinologists to fully clari fy the physiolog ica l relevance of th e functi onal interactions between chromaffin and steroidogeni c cells in the adrenal glands of lower vertebrates.