Search results for "acetylcholine."

Noncompetitive agonism at nicotinic acetylcholine receptors; functional significance for CNS signal transduction.

1995

The alkaloids (-)physostigmine (Phy), galanthamine (Gal) and codeine (Cod), and several derivatives and homologous compounds, can act as noncompetitive agonists (NCA) of nicotinic acetylcholine receptors (nAChR) from Torpedo electrocytes, frog and mammalian muscle cells, clonal rat pheochromocytoma cells, cultured hippocampal neurons and several ectopic expression systems, by interacting with a binding site on the alpha-subunits of these nAChRs that is insensitive to the natural transmitter, acetylcholine (ACh), and ACh-competitive agonists and antagonists. Several endogenous ligands, including opioid-type compounds, can also act via this site, albeit at higher concentrations than is typica…

Nicotinic receptor function in the mammalian central nervous system.

1995

The diversity of neuronal nicotinic receptors (nAChRs) in addition to their possible involvement in such pathological conditions as Alzheimer's disease have directed our research towards the characterization of these receptors in various mammalian brain areas. Our studies have relied on electrophysiological, biochemical, and immunofluorescent techniques applied to cultured and acutely dissociated hippocampal neurons, and have been aimed at identifying the various subtypes of nAChRs expressed in the mammalian central nervous system (CNS), at defining the mechanisms by which CNS nAChR activity is modulated, and at determining the ion permeability of CNS nAChR channels. Our findings can be sum…

Chapter 27: Peptidergic and cholinergic receptors on cultured astrocytes of different regions of the rat CNS

1992

Publisher Summary This chapter discusses whether astrocytes possess peptidergic and cholinergic receptors. There is strong evidence that in addition to neurons, astrocytes also express receptors for neurotransmitters and neuromodulators. The investigations were carried out in explant cultures of the spinal cord, brain-stem, cerebellum, and neocortex of fetal and newborn rats. By the means of autoradiography, it was demonstrated that astrocytes possess binding sites for the vasoactive peptides 3 H-Ang II, 125 I- VIP, 125 I-ET-l, ET-3, and 125 I-AVP. These findings are consistent with electrophysiological studies demonstrating that Ang II, ET, and AVP cause a depolarization of the glial membr…

Corrigendum to: α-Conotoxins EpI and AuIB switch subtype selectivity and activity in native versus recombinant nicotinic acetylcholine receptors (FEB…

2003

Corrigendum to: K-Conotoxins EpI and AuIB switch subtype selectivity and activity in native versus recombinant nicotinic acetylcholine receptors (FEBS 27779) [FEBS Letters 554 (2003) 219^223]C Annette Nickea;1, Marek Samochockib, Marion L. Loughnana, Paramjit S. Bansala, Alfred Maelickeb, Richard J. Lewisa; aInstitute for Molecular Bioscience, University of Queensland, Brisbane, Qld. 4072, Australia bInstitute for Physiological Chemistry and Pathobiochemistry, University of Mainz, D-55099 Mainz, Germany First published online 24 December 2003

Brain choline has a typical precursor profile.

1998

Choline is product and precursor to both acetylcholine and membrane phospholipids, and, in the brain, is ultimately provided by the circulation. The brain is protected from excess choline and choline deprivation by a refined system of homeostatic mechanisms that maintain a level of extracellular choline that, for its role as precursor, meets saturation criteria under normal conditions. The kinetic and activity profiles of choline are typical for a biosynthetic precursor.

PRESYNAPTIC MUSCARINIC CONTROL OF NORADRENALINE RELEASE

1980

ChemInform Abstract: Regioisomeric 3-, 4-, and 5-Aminomethylisoxazoles: Synthesis and Muscarinic Activity.

2010

Synthesis and in vitro evaluation of galanthamine derivatives for examination of nicotinic acetylcholine receptor system

2001

ISunmrary: The syntheses and radioactive labeling of several galanthamine derivatives, 6-O-demethyl-6-O-fluoroethylgalanthamine, 10-N-demethyl-lO-Nfluoroethylgalanthamine and N-methylgalanthaminium are reported. First ill vitro evaluations were carried out to determine their properties as allosterically potentiating ligands of nicotinic receptors. N-methylgalanthaminium was found to be a promising candidate for further investigations. The most commonly applied therapeutic approach to balance nicotinic cholinergic deficits in Alzheimer’s disease (AD) patients is the administration of acetylcholinesterase inhibitors (AChE-I) although they have been proven to be of limited therapeutic value [ …

Pre- and Postsynaptic Effects of Muscarinic Antagonists in the Isolated Guinea Pig Ileum

1986

Several compounds have been claimed to differentiate between subtypes of muscarinic receptors (2). In the experiments described in this chapter we have studied in the guinea-pig ileum whether the presynaptic muscarinic receptors of the cholinergic nerves differ from the postsynaptic muscarinic receptors of the longitudinal muscle in their affinities for several muscarinic antagonists (methylatropine; trihexyphenidyl; clozapine; DAMP). Inhibition by oxotremorine of the evoked release of acetylcholine (ACh) was used as a parameter of presynaptic activity, and the increase by oxotremorine of smooth muscle tension as a postsynaptic parameter. The affinity constants (pA2 values) of the antagonis…

Monoclonal antibodies FK1 and WF6 define two neighboring ligand binding sites on Torpedo acetylcholine receptor alpha-polypeptide.

1994

Previous studies have identified the sequence region flanking the invariant vicinal cysteinyl residues at positions 192 and 193 of the nicotinic acetylcholine receptor alpha-subunit as containing major elements of the binding site for acetylcholine and its agonists and antagonists, including antibody WF6 (Conti-Tronconi, B. M., Diethelm, B. M., Wu, X., Tang, F., Bertazzon, T., Schroder, B., Reinhardt-Maelicke, A., and Maelicke, A. (1991) Biochemistry 30, 2575-2584). Recently we have shown that the sequence region flanking lysine alpha 125 contains elements of the binding site for physostigmine and related ligands, including antibody FK1 (Schrattenholz, A., Godovac-Zimmerman, J., Schafer, H.…