Nicotinic acetylcholine receptors (nAchR) are a subtype of acetylcholine receptors that are activated by nicotine and allow the influx of monovalent (sodium) and divalent cations(calcium), however, the permeability of sodium and/or calcium maybe high or low depending on the subunit composition of the receptor. Nicotinic acetylcholine receptors are expressed widely in the central and peripheral nervous system in the presynaptic terminal, terminal bouton and post-synaptic neuron. Functionally nicotinic acetylcholine receptors in the pre-synaptic and postsynaptic terminals behave similarly. Nicotinic AChR are a family of acetylcholine gated pentameric receptors that are formed by the association of various combinations of mostly alpha, beta subunits and sometimes gamma delta, episilon subunits. In addition, receptors may be more diverse due the fact that some receptor have same subunits but the stoichiometry of the subunits is different.