Search results for " acetylcholine"
showing 10 items of 239 documents
The Non-neuronal Cholinergic System
2001
An increasing body of knowledge indicates that the cholinergic system is not confined to the nervous system, but is practically ubiquitous. The present paper will address the question of the non-neuronal cholinergic system in vascular endothelial cells (EC). In tissue sections of human skin, immunohistochemical studies using confocal laser scanning microscopy showed ChAT (choline acetyltransferase) activity in the EC of dermal blood vessels. Positive ChAT immunoreactivity was also demonstrated in monolayer cultures of human umbilical vein EC (HUVEC) and a human angiosarcoma EC line (HAEND). That the synthesizing enzyme is not only present in EC, but also active was shown by measuring ChAT a…
The cholinergic 'pitfall': acetylcholine, a universal cell molecule in biological systems, including humans.
1999
1. Acetylcholine (ACh) represents one of the most exemplary neurotransmitters. In addition to its presence in neuronal tissue, there is increasing experimental evidence that ACh is widely expressed in pro- and eukaryotic non-neuronal cells. Thus, ACh has been detected in bacteria, algae, protozoa, tubellariae and primitive plants, suggesting an extremely early appearance of ACh in the evolutionary process. 2. In humans, ACh and/or the synthesizing enzyme, choline acetyltransferase, has been demonstrated in epithelial cells (airways, alimentary tract, urogenital tract, epidermis), mesothelial (pleura, pericardium) and endothelial and muscle cells. In addition, immune cells express the non-ne…
Acetylcholine beyond neurons: the non-neuronal cholinergic system in humans
2008
Animal life is controlled by neurons and in this setting cholinergic neurons play an important role. Cholinergic neurons release ACh, which via nicotinic and muscarinic receptors (n- and mAChRs) mediate chemical neurotransmission, a highly integrative process. Thus, the organism responds to external and internal stimuli to maintain and optimize survival and mood. Blockade of cholinergic neurotransmission is followed by immediate death. However, cholinergic communication has been established from the beginning of life in primitive organisms such as bacteria, algae, protozoa, sponge and primitive plants and fungi, irrespective of neurons. Tubocurarine- and atropine-sensitive effects are obser…
Biochemical Characterization of a Novel Channel-Activating Site on Nicotinic Acetylcholine Receptors
1993
We have studied the interaction of the reversible acetylcholine esterase inhibitor (-)physostigmine and several structurally related compounds with the nicotinic acetylcholine receptor (nAChR) from Torpedo marmorata electric tissue by means of ligand-induced ion flux into nAChR-rich membrane vesicles, direct binding studies and photoaffinity labeling. (-)Physostigmine acts as a channel-activating ligand at low concentrations and as a direct channel blocker at elevated concentrations. Channel activation is not inhibited by desensitizing concentrations of ACh or ACh-competitive ligands (including alpha-bungarotoxin and D-tubocurarine) but is inhibited by antibody FK1 and several other compoun…
Nicotinic acetylcholine receptors have ligand-specific attachment point patterns.
1991
Employing a panel of synthetic peptides as representative structural elements of the nicotinic acetylcholine receptor from Torpedo electric organ, we recently identified three sequence regions of the receptor (alpha 55-74, alpha 134-153 and alpha 181-200) serving as subsites for the binding of high molecular weight antagonists of acetylcholine (Conti-Tronconi et al. 1990). The relative binding affinities to these subsites of alpha-bungarotoxin and three competitive antibodies varied in a ligand-specific fashion. Employing a set of homologous synthetic peptides differing from alpha 181-200 by the exchange of single amino acid residues along the sequence, we now find that ligand binding cruci…
The Non-neuronal Cholinergic System
2001
Acetylcholine, one of the most exemplary neurotransmitters, has been detected in bacteria, algae, protozoa, tubellariae and primitive plants, suggesting an extremely early appearance in the evolutionary process and a wide expression in non-neuronal cells. In plants (Urtica dioica), acetylcholine is involved in the regulation of water resorption and photosynthesis. In humans, acetylcholine and/or the synthesizing enzyme, choline acetyltransferase, have been demonstrated in epithelial (airways, alimentary tract, urogenital tract, epidermis), mesothelial (pleura, pericardium), endothelial, muscle and immune cells (granulocytes, lymphocytes, macrophages, mast cells). The widespread expression o…
Non-neuronal acetylcholine, a locally acting molecule, widely distributed in biological systems: expression and function in humans.
1998
Acetylcholine acts as a neurotransmitter in the central and peripheral nervous systems in humans. However, recent experiments demonstrate a widespread expression of the cholinergic system in non-neuronal cells in humans. The synthesizing enzyme choline acetyltransferase, the signalling molecule acetylcholine, and the respective receptors (nicotinic or muscarinic) are expressed in epithelial cells (human airways, alimentary tract, epidermis). Acetylcholine is also found in mesothelial, endothelial, glial, and circulating blood cells (platelets, mononuclear cells), as well as in alveolar macrophages. The existence of non-neuronal acetylcholine explains the widespread expression of muscarinic …
Release of non-neuronal acetylcholine from the isolated human placenta is mediated by organic cation transporters
2001
1. The release of acetylcholine was investigated in the human placenta villus, a useful model for the characterization of the non-neuronal cholinergic system. 2. Quinine, an inhibitor of organic cation transporters (OCT), reduced acetylcholine release in a reversible and concentration-dependent manner with an IC(50) value of 5 microM. The maximal effect, inhibition by 99%, occurred at a concentration of 300 microM. 3. Procaine (100 microM), a sodium channel blocker, and vesamicol (10 microM), an inhibitor of the vesicular acetylcholine transporter, were ineffective. 4. Corticosterone, an inhibitor of OCT subtype 1, 2 and 3 reduced acetylcholine in a concentration-dependent manner with an IC…
Chapter 19 Muscarinic activation of phosphatidylcholine hydrolysis
1996
Publisher Summary This chapter focuses on the muscarinic activation of phosphatidylcholine hydrolysis. The release of choline from tissues or cells is a sensitive indicator of an enhanced hydrolysis of phosphatidylcholine (PtdCho) and is easily determined by chemiluminescence. In certain cells, choline release may reflect the activity of a specific receptor-activated enzyme catalyzing PtdCho hydrolysis. A physiological role of the receptor-mediated release of choline in the brain is given by its role as biosynthetic precursor for acetylcholine (ACh) and phospholipids. When PtdCho hydrolysis is investigated to identify the phospholipase involved, the sole determination of enzymatic products …
Manipulation of HSP70-SOD1 Expression Modulates SH-SY5Y Differentiation and Susceptibility to Oxidative Stress-Dependent Cell Damage: Involvement in …
2023
The differentiation of neural progenitors is a complex process that integrates different signals to drive transcriptional changes, which mediate metabolic, electrophysiological, and morphological cellular specializations. Understanding these adjustments is essential within the framework of stem cell and cancer research and therapy. Human neuroblastoma SH-SY5Y cells, widely used in neurobiology research, can be differentiated into neuronal-like cells through serum deprivation and retinoic acid (RA) supplementation. In our study, we observed that the differentiation process triggers the expression of Heat Shock Protein 70 (HSP70). Notably, inhibition of HSP70 expression by KNK437 causes a dra…