α7 nACh receptors are homomeric, comprising of five α7 subunits. Along with α4β2* nAChRs, α7 nAChRs are the most widely expressed nAChRs in the central nervous system (Dani and De Biasi 2001; Hogg et al. 2003). α7 nAChRs are activated by acetylcholine and blocked by αBgtx with high calcium permeability and a rapid desensitization rate (Gotti and Clementi 2004). Presynaptic α7 nAChRs facilitate neurotransmitter release (Alkondon et al. 2000) and have been implicated in several effects of nicotine, including aversion and reward (Laviolette and van der Kooy 2003), anxiety-like behavior (Tucci et al. 2003), and working memory (Levin 2002). α7 KO mice have impaired attentional performance (Hoyle et al. 2006; Young et al. 2007) and α7 antagonists impair spatial working memory (Levin et al. 2003), while α7 agonists significantly improve learning, memory, and attentional function in rodents (Bitner et al. 2007; Boess et al. 2007; Levin et al. 1999), and reverse aging-induced cognitive impairments (Beracochea et al. 2008; Marighetto et al. 2008), but there is less evidence for the role of α7 nAChRs in nicotine reinforcement (Smith et al. 2007).
