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11. |
Bovine Posterior Pituitary: Presence of p65 (Synaptotagmin), PC1 PC2 and Secretoneurin in Large Dense Core Vesicles |
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Neuroendocrinology,
Volume 59,
Issue 2,
1994,
Page 169-175
Claudia Egger,
Rudolf Kirchmair,
Susanne Kapelari,
Reiner Fischer-Colbrie,
Ruth Hogue-Angeletti,
Hans Winkler,
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摘要:
The subcellular distribution of p65 (synaptotagmin), of the endoproteases PC1 and PC2 and of secretoneurin was studied in bovine posterior pituitary by differential and density gradient centrifugation. All these peptides were found to be present in the neurosecretory granules (large dense core vesicles). p65 can therefore participate not only in exocytosis from small synaptic vesicles but also from large dense core vesicles. Secretoneurin is a peptide derived from secretogranin II. Processing of the propeptide apparently occurs during axonal transport of the large dense core vesicles and is complete in the posterior pituitary. Thus, stimulation of the hypothalamic magnocellular neurons can lead to the release of this newly characterized, functional neuropeptide.
ISSN:0028-3835
DOI:10.1159/000126655
出版商:S. Karger AG
年代:1994
数据来源: Karger
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12. |
Morphological and Functional Heterogeneity of Frog Melanotrope Cells |
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Neuroendocrinology,
Volume 59,
Issue 2,
1994,
Page 176-182
José Luis Gonzalez de Aguilar,
Marie Christine Tonon,
Antonio Ruiz-Navarro,
Hubert Vaudry,
Francisco Gracia-Navarro,
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摘要:
Previous reports have described the heterogeneity of different pituitary cell types on the basis of morphological and physiological criteria. In the present study, we investigated the possible existence of distinct subpopulations of melanotrope cells in the intermediate lobe of the pituitary of the frog, Rana ridibunda. Separation of dispersed pars intermedia cells in a Percoll density gradient made it possible to isolate two fractions of melanotrope cells whose morphological and functional properties were further characterized. Analysis of the relative volume and number of various cellular organelles showed that high-density cells had a larger number of secretory granules than low-density cells. Concurrently, radioimmunoassay quantification revealed that the concentration of α-melanocyte-stimulating hormone (α-MSH) was 2 times higher in the heavy cell population. The rate of secretion of α-MSH from cultured melanotrophs was significantly higher in low-density than in high-density cells. Thyrotropin-releasing hormone (TRH) was more potent in stimulating α-MSH release from the low-density than from the high-density cell subset. In contrast, the response to TRH persisted for a longer time in the high-density cell subpopulation. Taken together, these data demonstrate the existence of two subpopulations of melanotrope cells, and indicate that the low-density cells have a secretory rate substantially greater than high-density ce
ISSN:0028-3835
DOI:10.1159/000126656
出版商:S. Karger AG
年代:1994
数据来源: Karger
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13. |
GABA Transport and Subcellular Distribution in the Rat Anterior Pituitary Gland |
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Neuroendocrinology,
Volume 59,
Issue 2,
1994,
Page 183-188
Beatriz Duvilanski,
Adriana Seilicovich,
Luciano Debeljuk,
Mercedes Lasaga,
M. del Carmen Diaz,
Daniel Pisera,
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摘要:
In this investigation we have studied the uptake of gamma aminobutyric acid (GABA) into anterior pituitary slices. Tissue:medium ratios of about 45:1 were obtained after a 30-min incubation. The process responsible for 3H-GABA uptake was temperature-sensitive and sodium-dependent. The kinetic constants of saturable GABA transport were: Km 4.141 µM and Vmax 0.973 pmol/min/mg protein, at 25 °C. The incorporation of GABA into anterior pituitary was inhibited by specific inhibitors of neuronal and/or glial uptake. The subcellular distribution of GABA was investigated by continuous sucrose density gradients and differential centrifugation. Most of the endogenous and labelled GABA was present in the soluble fraction. However, a small part of GABA was found in the particulate fraction. These observations indicate that the anterior pituitary gland is able to concentrate GABA which interacts with intracellular particle
ISSN:0028-3835
DOI:10.1159/000126657
出版商:S. Karger AG
年代:1994
数据来源: Karger
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