Evidence for expression of heteromeric serotonin 5-HT(3) receptors in rodents

J Neurochem. 2000 Jul;75(1):240-7. doi: 10.1046/j.1471-4159.2000.0750240.x.


The gene and cDNAs that encode a novel subunit of rodent serotonin 5-HT(3) receptors were isolated from mouse and rat tissues. Each of the new rodent subunits shares 40% amino acid identity with the rat 5-HT(3A) subunit and 73% identity with the human 5-HT(3B) subunit. Despite a relatively low level of structural conservation, sequence analysis and functional studies suggest that the new rodent subunits are orthologues of the human 5-HT(3B) subunit. In common with homologous human receptors, rat heteromeric 5-HT(3) receptors displayed a substantially larger single-channel conductance than homomeric 5-HT(3A) receptors. In addition, the rat heteromeric receptors were less sensitive to antagonism by tubocurarine. However, in contrast to human heteromeric receptors, those of the rat displayed pronounced inward rectification of both the whole-cell and single-channel current amplitudes. Transcripts of the mouse 5-HT(3A) and 5-HT(3B) subunits are coexpressed in several cell lines that possess endogenous 5-HT(3) receptors. In addition, treatment of rat PC12 cells with nerve growth factor induced expression of both subunit mRNAs, with a similar time course for accumulation of each transcript. The combination of functional data and expression patterns is consistent with the existence of heteromeric 5-HT(3) receptors in rodent neurons.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cloning, Molecular
  • DNA, Complementary
  • Electric Conductivity
  • Gene Expression*
  • Humans
  • Macromolecular Substances
  • Mice
  • Molecular Sequence Data
  • PC12 Cells
  • RNA, Messenger / analysis
  • Rats
  • Receptors, Serotonin / chemistry
  • Receptors, Serotonin / genetics*
  • Receptors, Serotonin / physiology
  • Receptors, Serotonin, 5-HT3
  • Recombinant Proteins / metabolism
  • Sequence Homology


  • DNA, Complementary
  • Macromolecular Substances
  • RNA, Messenger
  • Receptors, Serotonin
  • Receptors, Serotonin, 5-HT3
  • Recombinant Proteins