Search results for "Chromaffin Cells"
showing 10 items of 15 documents
11q Deletion or ALK Activity Curbs DLG2 Expression to Maintain an Undifferentiated State in Neuroblastoma
2020
High-risk 11q deleted neuroblastomas typically display undifferentiated/poorly differentiated morphology. Neuroblastoma is thought to develop from Schwann cell precursors and undifferentiated neural crest (NC) derived cells. It is therefore vital to understand mechanisms involved in the block of differentiation. We identify an important role for oncogenic ALK-ERK1/2-SP1 signaling in maintenance of undifferentiated NC-derived progenitors via repression of DLG2, a tumor suppressor in neuroblastoma. DLG2 is expressed in the ‘bridge signature’ that represents the transcriptional transition state when neural crest cells or Schwann Cell Precursors become chromaffin cells of the adrenal gland. We …
Effects of cigarette smoking or ingestion of nicotine on platelet 5-hydroxytryptamine (5-HT) levels in smokers and non-smokers.
1992
Platelets of healthy smokers and non-smokers were prepared and their content of 5-hydroxytryptamine was determined by HPLC with electrochemical detection. Platelet 5-HT levels in smokers (728 +/- 156 pmol per 10(8) platelets, mean +/- SEM, n = 9) were significantly higher than those in non-smokers (353 +/- 156 pmol per 10(8) platelets, n = 11). Smoking of a single cigarette caused a transient increase in platelet 5-HT levels by about 350% in non-smokers, but had no additional effect in smokers. Similarly, chewing of nicotine gum (4-8 mg nicotine) resulted in a transient increase in platelet 5-HT by about 100% in non-smokers, but not in smokers. In conclusion, smoking of cigarettes can cause…
Modulation by 5-HT3 and 5-HT4 receptors of the release of 5-hydroxytryptamine from the guinea-pig small intestine.
1993
The effects of agonists and antagonists of 5-hydroxytryptamine (5-HT) receptors on the release of endogenous 5-HT from enterochromaffin cells were studied in the vascularly perfused isolated guinea-pig small intestine. The experiments were done in the presence of tetrodotoxin in order to exclude a neuronally mediated influence on 5-HT release. The 5-HT3 receptor agonist 2-methyl-5-HT increased 5-HT release, and this effect was antagonized by 1 nmol/l tropisetron. Nanomolar concentrations of tropisetron, MDL 72,222 and granisetron decreased 5-HT release. Ondansetron (0.1 and 1 mumol/l) did not modify 5-HT release. 5-Methoxytryptamine, BIMU8 and cisapride concentration-dependently inhibited 5…
Automatic detection of large dense-core vesicles in secretory cells and statistical analysis of their intracellular distribution.
2010
Analyzing the morphological appearance and the spatial distribution of large dense-core vesicles (granules) in the cell cytoplasm is central to the understanding of regulated exocytosis. This paper is concerned with the automatic detection of granules and the statistical analysis of their spatial locations in different cell groups. We model the locations of granules of a given cell as a realization of a finite spatial point process and the point patterns associated with the cell groups as replicated point patterns of different spatial point processes. First, an algorithm to segment the granules using electron microscopy images is proposed. Second, the relative locations of the granules with…
NK1- and NK3-receptor mediated inhibition of 5-hydroxytryptamine release from the vascularly perfused small intestine of the guinea-pig
1997
The effects of tachykinins on the spontaneous release of 5-hydroxytryptamine (5-HT) from the enterochromaffin cells into the portal circulation was investigated in vitro using the vascularly perfused isolated guinea-pig small intestine. 5-HT was determined by HPLC with electrochemical detection. Test substances were applied intraarterially. Substance P (SP) caused a concentration-dependent decrease in 5-HT outflow with an EC50 of 50 pmol/l. Similarly, the selective NK1 receptor agonist SP methyl ester (1 nmol/l) significantly inhibited 5-HT outflow (to 51 +/- 3%). When tetrodotoxin (1 mumol/l) was added to the arterial perfusion medium, the inhibition by SP of 5-HT outflow was not affected.…
Nicotinic and muscarinic modulation of 5-hydroxytryptamine (5-HT) release from porcine and canine small intestine
1992
Strips of porcine and canine small intestine were incubated in vitro and the release of 5-hydroxytryptamine (5-HT) was determined by HPLC with electrochemical detection. The spontaneous outflow of 5-HT from the porcine and canine small intestine largely reflects calcium-dependent 5-HT secretion from enterochromaffin cells which are under a spontaneous neuronal, excitatory input as indicated by the inhibitory effect (30-40%) of tetrodotoxin. In both species, nicotine enhanced the release of 5-HT in a concentration-dependent manner by a maximum of about 50% at 100 microM. This effect was blocked by the nicotine receptor antagonist hexamethonium, but not by the subtype-selective nicotine recep…
Evidence that neuronally released vasoactive intestinal polypeptide inhibits the release of serotonin from enterochromaffin cells of the guinea pig s…
1991
Abstract. Isolated small intestinal segments of the guinea pig were arterially perfused and the release of serotonin (5-hydroxytryptamine) and 5-hydroxyindoleacetic acid into the portal venous effluent was determined by HPLC with electrochemical detection. Test substances were intra-arterially applied. The muscarine receptor agonist oxotremorine (1 μmol/l inhibited the release of 5-hydroxytryptamine by about 50%. In the presence of the neurotoxin tetrodotoxin, oxotremorine enhanced the release of 5-hydroxytryptamine by 145%, indicating that the inhibitory effect of oxotremorine was mediated by the release of a neurotransmitter. Exogenous vasoactive intestinal polypeptide ( 1-100 pmol/l inhi…
Cisplatin increases the release of 5-hydroxytryptamine (5-HT) from the isolated vascularly perfused small intestine of the guinea-pig: Involvement of…
1991
Isolated segments of the guinea-pig small intestine were vascularly perfused and the release of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) into the portal venous effluent determined by high pressure liquid chromatography with electrochemical detection. Release of acetylcholine from isolated superfused intestinal segments was determined as outflow of [3H]radioactivity from preparations preincubated with [3H]choline. Cisplatin (3 microM) increased the outflow of 5-HT and 5-HIAA by about 90%. At 30 and 100 microM cisplatin decreased the outflow of 5-HT and its metabolite by 40%-50%. The stimulatory effect of cisplatin was consistently observed only when the bicarbonate-…
Cholinergic modulation of the release of 5-hydroxytryptamine from the guinea pig ileum.
1987
Isolated segments of the guinea pig ileum were vascularly perfused and the release of 5-HT and its metabolite 5-HIAA into the portal venous effluent determined by HPLC with electrochemical detection. Test substances were applied via the arterial perfusion medium. Oxotremorine inhibited concentration-dependently the release of 5-HT and 5-HIAA (by 47% at 1 mumol/l). Scopolamine (0.1 mumol/l) did not affect the release of 5-HT and 5-HIAA, but antagonized the effect of oxotremorine. In the presence of TTX (1 mumol/l), oxotremorine (1 mumol/l) increased the release of 5-HT by 150% and that of 5-HIAA by 220%. This increase was completely blocked by scopolamine. Hexamethonium (100 mumol/l) and TTX…
Identification of SNARE complex modulators that inhibit exocytosis from an alpha-helix-constrained combinatorial library.
2003
Synthetic peptides patterned after the proteins involved in vesicle fusion [the so-called SNARE (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor) proteins] are potent inhibitors of SNARE complex assembly and neuronal exocytosis. It is noteworthy that the identification of peptide sequences not related to the SNARE proteins has not been accomplished yet; this is due, in part, to the structural constraints and the specificity of the protein interactions that govern the formation of the SNARE complex. Here we have addressed this question and used a combinatorial approach to identify peptides that modulate the assembly of the SNARE core complex and inhibit neuronal…