Physiological Diversity of Nicotinic Acetylcholine Receptors Expressed by Vertebrate Neurons

The last decade has revealed an astounding degree of physiological and st ruct ural divers it y in neurot ransmitteract ivated receptors. In part icular, mo­ lecular st udies of the acet ylcholine-gated recept ors in vert ebrate muscle cells and Torpedo elect rocyt es gave birt h to a new era of research on a relat ed s ubfamil y of nicotinic r eceptors ( nA Ch Rs) expressed by centr al and periph­ eral neurons. Th is review focuses on the nA ChR s ubt ypes expressed by neurons , viewed mainly from a ph ys iological pers pect ive. It is intended t o complement s everal excellent recent reviews o n muscle-type A ChRs (42, 45, 56) and on the anatomi cal dist ri buti on, bi ochemistry, and molecular bi ology of neuronal nAChRs (35, 61, 66, 95). The work s ummarized in this review has helped answer a long-standing q uest ion: How can t he wellknown behavioral, cognit ive, and addict ive eff ects of ni cotine be reconci led with the paucity of evidence for CNS s ynapses where t he t rans mission is mediat ed by nicot inic recept ors? The ident ificat ion of a large family of neuronal nA ChR s ubu nit genes and an array of funct ionally dist inct nA ChRs has given a bas is for t he divers e effects of nicot ine. P erhaps