HETEROGENEITY AND REGULATION OF NICOTINIC ACETYLCHOLINE-RECEPTORS

This chapter focuses on nicotinic acetylcholine receptors (nAChRs). This component emphasizes studies done using mammalian tissues or their derivatives, and using vertebrate nonmammalian systems. The chapter foscuses on the bases, manifestations, and functional significance of nAChR diversity. There are at least two populations of putative nAChRs in brain defined based on their ability to interact with 3H-labeled agonists or radiolabeled α-bungarotoxin. These binding sites are differentially regulated during development and exhibit differential anatomical distributions. Studies done on nAChRs in the periphery at the neuromuscular junction or on neural crest-derived cells are largely consistent with this dogma, in that chronic agonist treatment produces a decrease in receptor numbers and usually a comparable or quantitatively larger decrease in functional responsiveness. Chronic administration of two pyrethroid xenobiotics, bioallethrin and deltamethrin, produces an increase in levels of nAChRs. It is also becoming clear that diversity in mechanisms involved in the regulation of nAChR expression and function is built on the diversity of the nAChR family. © 1992, Academic Press Inc.