Acetylcholin Receptor, nicotinic

Nicotinic receptors (nicotinic acetylcholine receptors, nACHR) exist not only in the membrane of vertebrate skeletal muscle at the synapse between nerve and muscle (muscle-type nAChR) but also at various synapses throughout the brain, mainly at presynaptic positions (neuronal-type nAChR). Whereas the muscle-type nAChR is precisely composed of two a 1-subunits, one (3 -subunit, one y -subunit and one y -subunit (adult)... 

Nicotinic Acetylcholine Receptors. Nicotinic acetylcholine receptors are ligandgated ion channels whose opening is controlled by acetylcholine and nicotine agonists (196,209,210). They are transmembrane protein structures. Each receptor consists of five subunits. The structure is inserted in the plasma membrane with an aqueous channel in... 

Endosulfan Imidacloprid Organochlorine ChloronicotinyP GABA receptor Nicotinic acetylcholine receptor [46]... 

Nicotine functions as an agonist at a subtype of acetylcholine receptors, termed nicotinic receptors . Nicotinic acetylcholine receptors (nAChRs) are extremely variable in their molecular structure. They are composed of five subunits to form a hgand-binding site and an ionic pore. The variabihty of nAChRs subunit combinations and their location are responsible for diverse, sometimes paradoxical, physiological and pharmacological effects of nicotine, including pain rehef [1,2]. 

Autoantibodies are directed against nicotinic acetylcholine receptors in myasthenia gravis, resulting in receptor loss, skeletal muscle paralysis, and dysfunction (100). In addition, antibodies directed against voltage-gated Ca " channels produce similar neuromuscular dysfunction of Lambert-Eaton... 

Curare is a generic term for various South American arrow poisons. Curare has been used for centuries by the Indians along the Amazon and Orinoco rivers for immobilizing and paralyzing wild animals used for food. Preparations of curare are derived from Strychnos species, which contain quaternary neuromuscular alkaloids like tubocurarine. Tubocurarine is a potent antagonist at the nicotinic acetylcholine receptor. 

Dajas-Bailador F, Wonnacott S (2004) Nicotinic acetylcholine receptors and the regulation of neuronal signalling. Trends Pharmacol Sci 25 317-324... 

Gotti C, Zoli M, Clementi F (2006) Brain nicotinic acetylcholine receptors native subtypes and their relevance. Trends Pharmacol Sci 27 482-491... 

Jensen AA, Frolund B, Liljefors T et al (2005) Neuronal nicotinic acetylcholine receptors structural revelations, target identifications, and therapeutic inspirations. J Med Chem 48 4705—4745... 

Karlin A (2002) Emerging structure of the nicotinic acetylcholine receptors. Nat Rev Neurosci 3 102-114... 

Unwin N (2003) Structure and action of the nicotinic acetylcholine receptor explored by electron microscopy. FEES Lett 555 91-95... 

The open channel has in most cases a selective permeability, allowing a restricted class of ions to flow,for example Na+, K+, Ca++ or Cl- and, accordingly, these channels are called Na+-channels, K+-channels, Ca -channels and Cr-channels. In contrast, cation-permeable channels with little selectivity reject all anions but discriminate little among small cations. Little is known about the structures and functions of these non-selective cation channels [1], and so far only one of them, the nicotinic acetylcholine receptor (nAChR, see Nicotinic Receptors), has been characterized in depth [2, 3]. The nAChR is a ligand-gated channel (see below) that does not select well among cations the channel is even permeable to choline, glycine ethylester and tris buffer cations. A number of other plasma... 

Non-selective Cation Channels. Figure 1 The nicotinic acetylcholine receptor (nAChR) is localized within the cell membrane above the cell membrane is the synaptic cleft, below the cytoplasm. Drawing of the closed (left) and open (right) nAChR showing acetylcholine (ACh) binding and cation movement. Dimensions of the receptor were taken from references [2, 3]. 

Miyazawa A, Fujiyoshi Y, Stowell M et al (1999) Nicotinic acetylcholine receptor at 4.6 A resolution transverse tunnels in the channel wall. J Mol Biol 288 765-786... 

Nicotine is the main psychoactive ingredient of tobacco and is responsible for the stimulant effects and abuse/ addiction that may result form tobacco use. Cigarette smoking rapidly (in about 3 sec ) delivers pulses of nicotine into the bloodstream. Its initial effects are caused by its activation of nicotinic acetylcholine (nACh) receptors. nACh receptors are ligand-gated ion-channels and pre- and postsynaptically located. Reinforcement depends on an intact mesolimbic dopamine system (VTA). nACh receptors on VTA dopamine neurons are normally activated by cholinergic innervation from the laterodorsal tegmental nucleus or the pedunculopontine nucleus. 

HT3 receptors belong to the ligand-gated ion channel receptor superfamily, similar to the nicotinic acetylcholine or GABAa receptors and share elec-trophysiological and structural patterns. The receptors... 

The AMPA receptors for glutamate, the nicotinic acetylcholine receptor and the 5-HT3-receptor for serotonin are cation channels (Table 1). When they open, the major consequence is a sudden entry of Na+, depolarization and an excitatory postsynaptic potential (EPSP Fig. 1). 

Nicotinic Acetylcholine Receptor Nicotinic Receptors Nigrostriatal Tract/Pathway Nitrates... 

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