Nicotinic acetylcholine receptors (nAChR) are cholinergic receptors that form ligand-gated ion channels in the plasma membranes of certain neurons and on the postsynaptic side of the neuromuscular junctions. As ionotropic receptors, nAChR are directly linked to ion channels and do not use second messengers. nAChR are activated by the binding of the neurotransmitter Acetylcholine and can be opened by Nicotine [1].

nAChR are composed of different subunits including: alpha- (Cholinergic receptor, nicotinic, alpha 1, 3, 4, 5, 7 (nAChR alpha-1, nAChR alpha-3, nAChR alpha-4, nAChR alpha-5, nAChR alpha-7)), beta-( Cholinergic receptor, nicotinic, beta 1, 2 (nAChR beta-1, nAChR beta-2)) and nAChR gamma/epsilon.

nAChR activate transport of Ca('2+) extracellular region into the presynaptic neuron and thereby promote Gamma-aminobutyric acid (GABA) release [2], [3], [4], [5], [6], [7].

GABA activates a wide variety of GABA receptors (GABA-A receptor) on postsynaptic membrane, which are composed of different alpha, beta and gamma subunits including: GABA-A receptor alpha-1/beta-1/gamma-2; GABA-A receptor alpha-2/beta-3/gamma-2; GABA-A receptor alpha-4/beta-3/gamma-2, and GABA-A receptor alpha-6/beta-2/gamma-2 [8], [9], [10].

Activation of GABA-A receptor leads to increased Cl('-) extracellular region import into the cell and promotes hyperpolarization of postsynaptic neurons [11], [12].

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