&lt;i&gt;In vitro &lt;/i&gt;Release of ACTH from Dispersed Rat Pars Intermedia Cells. I. Effect of Secretagogues

Kraicer, Jacob; Morris, Alison

doi:10.1159/000122471

Cited by 30 publications

(12 citation statements)

References 12 publications

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“…The PI of the rat adenohypophysis contains ACTH, as defined both by immunohistologic techniques [Phifer and Spicer, 1970;Baker and Drum mond, 1972;Moriarty and Halmi, 1972;Moriarty, 1973;Kraicer et al, 1973] as well as by direct bioassay [Kraicer et al, 1973;Kraicer and D hariwal, 1974;K raicer and Morris, 1976]. The immunohistological results, however, are not definitive because of the commonality in amino acid sequences between ACTH and «MSH [Li, 1972;Baker, 1973;Howe, 1973], and between ACTH and the corticotropin-like intermediate lobe peptide [Scott et al, 1974] and lipotropin [Li, 1972]; the latter 2 peptides are also present in the PI [Moon et al, 1973;Dessy et Herlant, 1974;Scott et al, 1974].…”

Section: Discussionmentioning

confidence: 99%

In vitro Release of ACTH from Dispersed Rat Pars Intermedia Cells. II. Effect of Neurotransmitter Substances

Kraicer¹,

Morris²

1976

Neuroendocrinology

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Studies were carried out to test the responsiveness of dispersed pars intermedia (PI) cells to a number of neurotransmitter substances known to be present in the PI. These substances were tested over an extended dose range. The catecholamines, adrenaline, noradrenaline, and dopamine inactivated PI ACTH at high concentrations; at lower concentrations, they were without effect. Histamine and carbachol had no effect on ACTH release. 5-hydroxytryptamine stimulated ACTH release in a dose-related manner, from 10^–6 to 10^–3M, while having no effect on ACTH release from the pars distalis (PD). We conclude that the release of ACTH from the PI may be controlled by direct serotonergic innervation.

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Section: Discussionmentioning

confidence: 99%

In vitro Release of ACTH from Dispersed Rat Pars Intermedia Cells. II. Effect of Neurotransmitter Substances

Kraicer¹,

Morris²

1976

Neuroendocrinology

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“…Following dispersion, the cells were collected by centrifugation and the cell pellet was then resuspended in KrebsRinger bicarbonate containing 0.1% bovine serum albumin (KRBA). Small aliquots were taken for cell counts and histological examination [Kraicer and Morris, 1976a], Onethird of the total volume was then removed as the non-incubated sample, the medium harvested by centrifugation, immediately chilled, and acidified to 0 .1 n HC1. Small aliquots of this acidified medium were then taken for hormone assay and the remainder was snap frozen for subsequent chromatography.…”

Section: Methodsmentioning

confidence: 99%

In vitro Release of ACTH from Dispersed Rat Pars intermedia Cells. III. Multiple Forms of ACTH Biological Activity

Kraicer¹,

Elliot²,

Zimmerman³

1978

Neuroendocrinology

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We have reported that both an extract of rat hypothalamus-stalk-median eminence (HE) and 5-hydroxytryptamine (5-HT) will stimulate the release of ACTH biological activity from acutely, non-enzymically dispersed rat pars intermedia (PI) cells. We have also found that the ACTH activity within the PI cells is composed of 4 chromatographically separable entities, but only a small proportion of the total ACTH activity co-elutes with ACTH^1-39. In the present study we subjected the media, after incubation of PI cells with either HE or 5-HT, to sequential chromatography on Sephadex G-50 F and G-100 SF. We found the same 4 ACTH-like moieties as in the PI cell extracts. Only the release of the 2 earliest eluting components, presumably of much larger molecular dimensions than ACTH^1-39, was enhanced by either HE or 5-HT. There was no augmented release of the ACTH component having molecular dimensions similar to ACTH¹"³⁹. Thus, in our in vitro system, the ACTH biological activity released from PI cells is not the size of ACTH^1-39, but is composed of at least 2 much larger molecules which possess ACTH (as well as some MSH) biological activity.

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“…Pooled posterior lobes from 40 animals were washed several times with fresh buffer and were sucked several times through a long plastic tubing (3 mm inside diameter) attached to a 50-ml plastic disposable syringe. This procedure disperses the cells from the pars intermedia which is a very loose tissue (20). The remaining pars nervosa was separated by decantation and the resulting supernatant was then filtered through a fine nylon net (100 mesh) to remove any remaining small fragments of the anterior lobe.…”

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Biosynthesis of beta-endorphin from beta-lipotropin and a larger molecular weight precursor in rat pars intermedia.

Crine¹,

Gianoulakis²,

Seidah³

et al. 1978

Proc. Natl. Acad. Sci. U.S.A.

142

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When isolated rat pars intermedia cells were incubated for 10 min with radioactive amino acids, one major labeled protein with a molecular weight of 30,000 ± 1500 was extracted. This protein was shown to contain in its sequence the antigenic determinants for corticotropin and P-melanotropin by immunoprecipitation. When the radioactivity incorporated into this large molecular weight protein during the first 10 min was chased by a further incubation in presence of an excess of unlabeled amino acid, the initial protein was degraded into several smaller peptides including #-endorphin and ,¢lipotropin.Another 18,000-dalton peptide was also observed and was tentatively identified as a large molecular form of corticotropin. From the kinetics of the maturation of the initial precursor, it is concluded that the initial cleavage of the 30,000-dalton peptide gives rise to f-lipotropin and the 18,000-dalton form of corticotropin. f-Lipotropin is subsequently cleaved to form 0-endorphin. The intermediate lobe of the pituitary has been shown to contain a number of peptide hormones including corticotropin (ACTH) (1-3), a-melanotropin (a-MSH) (4,5), corticotropinlike intermediate lobe peptide (CLIP) (5, 6), f,-lipotropin (13-LPH) (7-9), fl-endorphin (9-11), and f3-MSH (4, 12). a-MSH and CLIP are structurally related to ACTH; ,B-LPH is considered to be the precursor for , .Immunocytochemical studies have shown that ACTH and f3-LPH immunoreactive peptides occur in all of the parenchymal cells of the pars intermedia (7, 9, 11). Furthermore, when these cells were observed under the electron microscope, staining for ACTH and fl-LPH was seen in all the granules and in the structures of the rough endoplasmic reticulum (9, 14). These results agree with the hypothesis of a common precursor for ACTH and fl-LPH, which has recently had two good experimental confirmations (15-17).In both studies, the experimental model was the ACTHsecreting mouse pituitary cell line used a double-immunoprecipitation technique to isolate labeled proteins from cells incubated with radioactive amino acids. Roberts and Herbert (16, 17) prepared a cell-free translation product from a poly(A)-containing mRNA fraction obtained from AtT-20 cells. In both cases, the ACTH/,B-LPH precursor seems to be a 28,000-31,000 dalton protein that is cleaved into f3-LPH, fl-endorphin, and several high molecular weight forms of ACTH (15,18,19).The primary purpose of this study was to investigate the ACTH/,B-endorphin biosynthetic pattern in the intermediate lobe of rat pituitaries. We report here that, during short incubations with labeled amino acids, rat pituitary intermediate lobe cells synthesize predominantly one 30,000 + 1500 dalton protein that bears antigenic determinants for both ,B-MSH and ACTH. Pulse-chase labeling shows that this peptide matures into several products including f,-LPH and ,B-endorphin. METHODSPreparation of Rat Pars Intermedia Cells. Sprague-Dawley male rats (Canadian Breeding Laboratory, St-Constant, Quebec) (150-200 g) were killed by decapit...

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<i>In vitro </i>Release of ACTH from Dispersed Rat Pars Intermedia Cells. I. Effect of Secretagogues

Cited by 30 publications

References 12 publications

<i>In vitro</i> Release of ACTH from Dispersed Rat Pars Intermedia Cells. II. Effect of Neurotransmitter Substances

<i>In vitro</i> Release of ACTH from Dispersed Rat Pars Intermedia Cells. II. Effect of Neurotransmitter Substances

<i>In vitro </i>Release of ACTH from Dispersed Rat Pars intermedia Cells. III. Multiple Forms of ACTH Biological Activity

Biosynthesis of beta-endorphin from beta-lipotropin and a larger molecular weight precursor in rat pars intermedia.

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