Stimulation of this receptor subtype is also associated with growth hormone secretion. People with the inactive CHRNA4 mutation Ser248Phe are an average of 10 cm (4 inches) shorter than average and predisposed to obesity.[3] A 2015 review noted that stimulation of the α4β2 nicotinic receptor in the brain is responsible for certain improvements in attentional performance;[4] among the nicotinic receptor subtypes, nicotine has the highest binding affinity at the α4β2 receptor (ki=1 nM), which is also the primary biological target that mediates nicotine's addictive properties.[5]
The receptors exist in the two stoichiometries:
(α4)2(β2)3 receptors have high sensitivity to nicotine and low Ca2+ permeability (HS receptors)
(α4)3(β2)2 receptors have low sensitivity to nicotine and high Ca2+ permeability (LS receptors)
Structure
The α4β2 receptor assemble in two distinct stoichiometric forms. One stoichiometry contains three α4 and two β2 subunits [ (α4)3(β2)2 ] whereas the other stoichiometry contains two α4 and three β2 [ (α4)2(β2)3 ].
The x-ray structure of the (α4)2(β2)3 receptor is known since 2016[6] and reveals a circular α–β–β–α–β ordering of subunits.
^"Nicotine: Biological activity". IUPHAR/BPS Guide to Pharmacology. International Union of Basic and Clinical Pharmacology. Retrieved 7 February 2016. Kis as follows; α2β4=9900nM [5], α3β2=14nM [1], α3β4=187nM [1], α4β2=1nM [4,6]. Due to the heterogeneity of nACh channels we have not tagged a primary drug target for nicotine, although the α4β2 is reported to be the predominant high affinity subtype in the brain which mediates nicotine addiction [2-3].
^Dallanoce, Clelia; Matera, Carlo; Amici, Marco De; Rizzi, Luca; Pucci, Luca; Gotti, Cecilia; Clementi, Francesco; Micheli, Carlo De (2012-07-01). "The enantiomers of epiboxidine and of two related analogs: Synthesis and estimation of their binding affinity at α4β2 and α7 neuronal nicotinic acetylcholine receptors". Chirality. 24 (7): 543–551. doi:10.1002/chir.22052. ISSN1520-636X. PMID22566097.
^Zwart, R.; Carbone, A. L.; Moroni, M.; Bermudez, I.; Mogg, A. J.; Folly, E. A.; Broad, L. M.; Williams, A. C.; Zhang, D.; Ding, C.; Heinz, B. A.; Sher, E. (2008). "Sazetidine-A is a potent and selective agonist at native and recombinant alpha 4 beta 2 nicotinic acetylcholine receptors". Mol. Pharmacol. 73 (6): 1838–43. doi:10.1124/mol.108.045104. PMID18367540. S2CID24632914.
^Bunnelle, William H.; Daanen, Jerome F.; Ryther, Keith B.; Schrimpf, Michael R.; Dart, Michael J.; Gelain, Arianna; Meyer, Michael D.; Frost, Jennifer M.; Anderson, David J.; Buckley, Michael; Curzon, Peter; Cao, Ying-Jun; Puttfarcken, Pamela; Searle, Xenia; Ji, Jianguo; Putman, C. Brent; Surowy, Carol; Toma, Lucio; Barlocco, Daniela (2007). "Structure-activity studies and analgesic efficacy of N-(3-pyridinyl)-bridged bicyclic diamines, exceptionally potent agonists at nicotinic acetylcholine receptors". J. Med. Chem. 50 (15): 3627–44. doi:10.1021/jm070018l. PMID17585748.
^Frost (Née Pac, Jennifer M.; Bunnelle, William H.; Tietje, Karin R.; Anderson, David J.; Rueter, Lynne E.; Curzon, Peter; Surowy, Carol S.; Ji, Jianquo; Daanen, Jerome F.; Kohlhaas, Kathy L.; Buckley, Michael J.; Henry, Rodger F.; Dyhring, Tino; Ahring, Philip K.; Meyer, Michael D. (2006). "Synthesis and structure-activity relationships of 3,8-diazabicyclo[4.2.0]octane ligands, potent nicotinic acetylcholine receptor agonists". J. Med. Chem. 49 (26): 7843–53. doi:10.1021/jm060846z. PMID17181167.
^Ji, Jianguo; Schrimpf, Michael R.; Sippy, Kevin B.; Bunnelle, William H.; Li, Tao; Anderson, David J.; Faltynek, Connie; Surowy, Carol S.; Dyhring, Tino; Ahring, Philip K.; Meyer, Michael D. (2007). "Synthesis and structure-activity relationship studies of 3,6-diazabicyclo[3.2.0]heptanes as novel alpha4beta2 nicotinic acetylcholine receptor selective agonists". J. Med. Chem. 50 (22): 5493–508. doi:10.1021/jm070755h. PMID17929796.
^Albrecht, Brian K.; Berry, Virginia; Boezio, Alessandro A.; Cao, Lei; Clarkin, Kristie; Guo, Wenhong; Harmange, Jean-Christophe; Hierl, Markus; Huang, Liyue; Janosky, Brett; Knop, Johannes; Malmberg, Annika; McDermott, Jeff S.; Nguyen, Hung Q.; Springer, Stephanie K.; Waldon, Daniel; Woodin, Katrina; McDonough, Stefan I. (2008). "Discovery and optimization of substituted piperidines as potent, selective, CNS-penetrant alpha4beta2 nicotinic acetylcholine receptor potentiators". Bioorg. Med. Chem. Lett. 18 (19): 5209–12. doi:10.1016/j.bmcl.2008.08.080. PMID18789861.
^Springer, Stephanie K.; Woodin, Katrina S.; Berry, Virginia; Boezio, Alessandro A.; Cao, Lei; Clarkin, Kristie; Harmange, Jean-Christophe; Hierl, Markus; Knop, Johannes; Malmberg, Annika B.; McDermott, Jeff S.; Nguyen, Hung Q.; Waldon, Daniel; Albrecht, Brian K.; McDonough, Stefan I. (2008). "Synthesis and activity of substituted carbamates as potentiators of the alpha4beta2 nicotinic acetylcholine receptor". Bioorg. Med. Chem. Lett. 18 (20): 5643–7. doi:10.1016/j.bmcl.2008.08.092. PMID18805006.
^Gao, Yongjun; Kuwabara, Hiroto; Spivak, Charles E.; Xiao, Yingxian; Kellar, Kenneth; Ravert, Hayden T.; Kumar, Anil; Alexander, Mohab; Hilton, John; Wong, Dean F.; Dannals, Robert F.; Horti, Andrew G. (2008). "Discovery of (−)-7-methyl-2-exo-[3'-(6-[18F]fluoropyridin-2-yl)-5'-pyridinyl]-7-azabicyclo[2.2.1]heptane, a radiolabeled antagonist for cerebral nicotinic acetylcholine receptor (alpha4beta2-nAChR) with optimal positron emission tomography imaging properties". J. Med. Chem. 51 (15): 4751–64. doi:10.1021/jm800323d. PMID18605717.
^Abdrakhmanova, G. R.; Damaj, M. I.; Carroll, F. I.; Martin, B. R. (2006). "2-Fluoro-3-(4-nitro-phenyl)deschloroepibatidine is a novel potent competitive antagonist of human neuronal alpha4beta2 nAChRs". Mol. Pharmacol. 69 (6): 1945–52. doi:10.1124/mol.105.021782. PMID16505153. S2CID96557182.
^Kashiwada, Yoshiki; Aoshima, Akihiro; Ikeshiro, Yasumasa; Chen, Yuh-Pan; Furukawa, Hiroshi; Itoigawa, Masataka; Fujioka, Toshihiro; Mihashi, Kunihide; Cosentino, L. Mark; Morris-Natschke, Susan L.; Lee, Kuo-Hsiung (2005). "Anti-HIV benzylisoquinoline alkaloids and flavonoids from the leaves of Nelumbo nucifera, and structure–activity correlations with related alkaloids". Bioorganic & Medicinal Chemistry. 13 (2): 443–8. doi:10.1016/j.bmc.2004.10.020. PMID15598565.
^Fedorov, N. B.; Benson, L. C.; Graef, J.; Lippiello, P. M.; Bencherif, M. (February 2009). "Differential pharmacologies of mecamylamine enantiomers: positive allosteric modulation and noncompetitive inhibition". J. Pharmacol. Exp. Ther. 328 (2): 525–32. doi:10.1124/jpet.108.146910. PMID18957576. S2CID31849794.
^Matera, Carlo; Pucci, Luca; Fiorentini, Chiara; Fucile, Sergio; Missale, Cristina; Grazioso, Giovanni; Clementi, Francesco; Zoli, Michele; De Amici, Marco (2015-08-28). "Bifunctional compounds targeting both D2 and non-α7 nACh receptors: Design, synthesis and pharmacological characterization". European Journal of Medicinal Chemistry. 101: 367–383. doi:10.1016/j.ejmech.2015.06.039. PMID26164842.