Acetylcholine receptors metabotropic

There are two major types of receptor which are activated by neurotransmitters. These are the ionotropic and metabotropic receptors. The former receptor type is illustrated by the amino acid neurotransmitter receptors for glutamate, gamma-aminobutyric acid (GABA) and glycine, and the acetylcholine receptors of the nicotinic type. These are examples of fast transmitters in that they rapidly open and close the ionic channels in... 

Blanc E. M., Kelly J. F., Mark R. J., Wag G., and Mattson M. P. (1997). 4-hydroxynonenal, an aldehydic product of lipid peroxidation, impairs signal transduction associated with muscarinic acetylcholine and metabotropic glutamate receptors Possible action on Gaq/11. J. Neurochem. 69 570-580. 

Nicotine is an addictive drug that activates a diverse subset of ionotropic acetylcholine receptors. Most cholinergic actions in brain, both by ionotropic and metabotropic receptors, are modulatory, and very few fast synapses exist that utilize... 

Two groups of acetylcholine receptors have been identified in humans the muscarinic (mAChR) and nicotinic (nAChR) receptors, named after their artificial activating ligands, muscarine and nicotine. These receptors function through entirely different mechanisms, either as a slow acting metabotropic G-protein-coupled receptor (mAChR) or fast acting ion-channel type receptor (nAChR). 

Some studies have also shown that retrograde endocannabinoid signalling can also be induced by postsynaptic activation of metabotropic glutamatergic receptors (mGluRs) and muscarinic acetylcholine receptors (mAChRs). Like fhe... 

As with most other neurotransmitter receptors, acetylcholine receptors are classified into ionotropic and metabotropic receptors. Ionotropic acetylcholine receptors are referred to as "nicotinic" because they are responsive to nicotine, an alkaloid compound present in cigarettes. Metabotropic acetylcholine receptors are referred to as "muscarinic" because they are sensitive to muscarine, a mushroom compound. Cholesterol has been reported to modulate the activity of both receptor types, yet most studies have been focused on the interaction... 

The available data are consistent with the present thesis that cholinergic inputs to cerebral cortex mediate intradendritic events fundamental to conscious activity as a primary role, and that cholinergic modulation of electrophysiological activity may be secondary, even epiphenomenal. Transduction pathways exist whereby muscarinic receptors (and possibly nicotinic receptors acting presynaptically to inhibit acetylcholine release) may lead to actions on the cytoskeleton directly relevant to consciousness. The thesis presented here describes these pathways and also suggests a possible explanation for the diversity of neuromodulators and metabotropic receptors. Accordingly, qualitative aspects of our consciousness would be finely tuned by a number of neurochemicals, prominent among which is acetylcholine. 

Figure 5. Cartoon of a cholinergic synapse showing major steps in the synthesis of acetylcholine. The two major receptor types, the ionotropic nicotinic receptor and the metabotropic muscarinic receptor, are shown (see also Chapter 1). Presynaptic muscarinic (M2) and nicotinic receptors are also depicted. Drugs which have been widely used to manipulate the cholinergic systems, and which are mentioned in the text, include the muscarinic receptor antagonists scopolamine and atropine and the nicotinic receptor agonist nicotine. Anticholinesterases (discussed elsewhere in this volume) include drugs such as physostigmine, rivastigmine, donepezil, and galanthamine.

Metabotropic G-protein linked receptors are also modulated by general anesthetics. In particular, the current produced through activation of muscarinic receptors (Ml) for acetylcholine and the serotonergic receptor 5HT2 is inhibited by halothane, isoflurane and enflurane (Lin et al., 1993 Minami et al., 1994 Durieux, 1995). Ketamine inhibits muscarinic receptors although there is no stereospecificity of inhibition (Durieux Nietgen, 1997). The S-isomer of ketamine is more potent as an anesthetic than the R-isomer (Benthuysen et al., 1989). It is thus unlikely that the Ml muscarinic receptor plays a role in... 

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