Unique general anesthetic binding sites within distinct conformational states of the nicotinic acetylcholine receptor

Int Rev Neurobiol. 2003:54:1-50. doi: 10.1016/s0074-7742(03)54002-8.

Abstract

General anesthesia is a complex behavioral state provoked by the pharmacological action of a broad range of structurally different hydrophobic molecules called general anesthetics (GAs) on receptor members of the genetically linked ligand-gated ion channel (LGIC) superfamily. This superfamily includes nicotinic acetylcholine (AChRs), type A and C gamma-aminobutyric acid (GABAAR and GABACR), glycine (GlyR), and type 3 5-hydroxytryptamine (5-HT3R) receptors. This review focuses on recent advances in the localization of GA binding sites on conformationally and compositionally distinct AChRs. The experimental evidence outlined in this review suggests that: 1. Several neuronal-type AChRs might be targets for the pharmacological action of distinct GAs. 2. The molecular components of a specific GA binding site on a certain receptor subtype are different from the structural determinants of the locus for the same GA on a different receptor subtype. 3. There are unique binding sites for distinct GAs in the same receptor protein. 4. A GA can activate, potentiate, or inhibit an ion channel, indicating the existence of more than one binding site for the same GA. 5. The affinity of a specific GA depends on the conformational state of the receptor. 6. GAs inhibition channels by at least two mechanisms, an open-channel-blocking and/or an allosteric mechanism. 7. Certain GAs may inhibit AChR function by competing for the agonist binding sites or by augmenting the desensitization rate.

Publication types

  • Review

MeSH terms

  • Anesthetics, General / chemistry
  • Anesthetics, General / pharmacokinetics*
  • Animals
  • Binding Sites / physiology
  • Humans
  • Ion Channels / pharmacokinetics*
  • Molecular Conformation
  • Protein Subunits / chemistry
  • Receptors, Nicotinic / chemistry*
  • Receptors, Nicotinic / physiology*
  • Steroids / pharmacokinetics

Substances

  • Anesthetics, General
  • Ion Channels
  • Protein Subunits
  • Receptors, Nicotinic
  • Steroids