Acetylcholine nicotine

Acetylcholine nicotinic (LGIC) Na+, K+ and Ca2 + conductance Nicotine, suxamethonium Tubocurarine, a-conotoxins, a-bungarotoxin... 

Acetylcholine Nicotine is an agonist at nicotinic acetylcholine receptors, which were named after the drug (Taylor 1996). Nicotine opens the... 

Nicotinic receptors are of the ionotropic type which, on stimulation by acetylcholine, nicotine or related agonists, open to allow the passage of sodium ions into the neuron. There are structural differences between the peripheral and neuronal receptors, the former being pentamers composed of two alpha and one beta, gamma and delta sub-units while the latter consist of single alpha and beta sub-units. It is now known that there are at least four variants of the alpha and two of the beta sub-units in the brain. In Alzheimer s disease it would appear that there is a selective reduction in the nicotinic receptors which contain the alpha 3 and 4 sub-units (Figure 2.9). 

Ion channels (center). These receptors contain ligand-gated ion channels. Binding of the signaling substance opens the channels for ions such as Na, Ca, and Cl . This mechanism is mainly used by neurotransmitters such as acetylcholine (nicotinic receptor see p.224) and GABA (A receptor see p.354). 

No difference has been observed in the interactions of the two enantiomers of isoflurane with hpid bilayers. But the (5)-enantiomer of isoflurane is two times more active than the (7 )-enantiomer toward a calcium channel receptor, that is sensitive to volatile anesthetic agents, while nodifference in activity has been observed toward an anesthetic nonsensitive receptor. The (5)-enantiomer of isoflurane is also more active than the (R)-enantiomer toward acetylcholine nicotinic receptor and GABA receptor. These data strongly suggest that fluoroethers interact not only with cerebral membranous lipids but also with receptor proteins. 

Changeux JP, Galzi JL, Devilhers-Thiery A, et al The functional architecture of the acetylcholine nicotinic receptor explored by affinity labeling and site-directed mutagenesis. Q Rev Biophys 25 395-432, 1992... 

It acts by dual mechanism i.e. inhibition of central ChE and as an agonist on central acetylcholine nicotinic receptors. 

The tobacco compound nicotine has been used as an insecticide for over 200 years. It is especially effective against sucking insects, such as aphids, and has excellent contact activity. Related compounds are neonicotinoids (e.g., imidacloprid), which have similar insecticidal activity, but are less toxic to mammals. Nicotine and imidacloprid mimic the action of acetylcholine, which is the major excitatory neurotransmitter in an insect s central nervous system. The action of acetylcholine is stopped by the enzyme acetylcholinesterase, which rapidly breaks down acetylcholine. Nicotine and imidacloprid are also neuroexcitatory, but do so persistendy, since they are not affected by acetylcholinesterase. Overstimulation of the nervous system often leads to convulsions, paralysis, and death. 

Bisbenzylisoquinolines (macrocyclic or linear, formed by 2 benzylisoquinolines) (+)-tubocurarine (macrocyclic) (acetylcholine (nicotinic) receptor antagonist and skeletal muscle relaxant major component of Chondrodendron species (Menispermaceae) pareira bark-derived curare arrow poison) dauricine (linear) (Menispermaceae curarelike anaesthetic) rodiasine (macrocyclic) (Ocotoea venenosa (Lauraceae) curare-like skeletal muscle relaxant) cepharanthine (macrocyclic) (Stephania species (Menispermaceae) anti-mycobacterial active against leprosy and tuberculosis). 

Fig. 1.5 Agonistic or antagonistic modulation of neuroreceptors by alkaloids that mimic neurotransmitters, (a) Interaction at cholinergic neurotransmitters that bind acetylcholine nicotinic acetylcholine receptor...

Recently a systematic investigation of the conformational and electronic aspects of pharmacology has been launched in our laboratory, using the PCILO method. The compounds investigated for which results are already available are those which have been previously investigated by the EHT method acetylcholine, nicotine and muscarine 84>, serotonine 85 histamine 86), ephedrine, norephedrine and dopamine 87>, but also others tyramine, noradrenaline, ephedrine, amphetamine and privine 87), a number of barbiturates 88 and a number... 

Cholinergic acetylcholine nicotinic muscle type cation channel (Na+>K+) ... 

Increased action AChN Acetylcholine nicotinic receptor... 

AChN Acetylcholine nicotinic receptor GnRH Gonadotrophin-releasing hormone... 

Nicotinic agonists acetylcholine, nicotine, carba-chol, arecoline, suberyldicholine, tetramethylammo-nium, phenyltrimethylammonium, dimethylphenyl-piperazine. ... 

Atropine 100 nmol Inhibits effects of acetylcholine, nicotine, and muscarine but not hypoxia... 

Ganglionic (sympathetic and parasympathetic) acetylcholine nicotine physostigmine hexamethonium (7-24)i tubocurarine (weak) nicotine (if in excess)... 

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