Response profiles to amino acid odorants of olfactory glomeruli in larval Xenopus laevis

J Physiol. 2007 Jun 1;581(Pt 2):567-79. doi: 10.1113/jphysiol.2007.130518. Epub 2007 Mar 8.


Glomeruli in the vertebrate olfactory bulb (OB) appear as anatomically discrete modules receiving direct input from the olfactory epithelium (OE) via axons of olfactory receptor neurons (ORNs). The response profiles with respect to amino acids (AAs) of a large number of ORNs in larval Xenopus laevis have been recently determined and analysed. Here we report on Ca(2+) imaging experiments in a nose-brain preparation of the same species at the same developmental stages. We recorded responses to AAs of glomeruli in the OB and determined the response profiles to AAs of individual glomeruli. We describe the general features of AA-responsive glomeruli and compare their response profiles to AAs with those of ORNs obtained in our previous study. A large number of past studies have focused either on odorant responses in the OE or on odorant-induced responses in the OB. However, a thorough comparison of odorant-induced responses of both stages, ORNs and glomeruli of the same species is as yet lacking. The glomerular response profiles reported herein markedly differ from the previously obtained response profiles of ORNs in that glomeruli clearly have narrower selectivity profiles than ORNs. We discuss possible explanations for the different selectivity profiles of glomeruli and ORNs in the context of the development of the olfactory map.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 6-Cyano-7-nitroquinoxaline-2,3-dione / pharmacology
  • Amino Acids / pharmacology*
  • Animals
  • Calcium / metabolism
  • Calcium Signaling / drug effects*
  • Excitatory Amino Acid Antagonists / pharmacology
  • In Vitro Techniques
  • Larva / metabolism
  • Microscopy, Confocal
  • Olfactory Bulb / drug effects*
  • Olfactory Bulb / embryology
  • Olfactory Bulb / metabolism
  • Olfactory Mucosa / drug effects*
  • Olfactory Mucosa / embryology
  • Olfactory Mucosa / metabolism
  • Olfactory Pathways / drug effects*
  • Olfactory Pathways / embryology
  • Olfactory Pathways / metabolism
  • Olfactory Receptor Neurons / drug effects
  • Olfactory Receptor Neurons / metabolism
  • Receptors, Odorant / drug effects
  • Receptors, Odorant / metabolism
  • Smell / drug effects*
  • Time Factors
  • Valine / analogs & derivatives
  • Valine / pharmacology
  • Xenopus laevis / embryology
  • Xenopus laevis / physiology*


  • Amino Acids
  • Excitatory Amino Acid Antagonists
  • Receptors, Odorant
  • 6-Cyano-7-nitroquinoxaline-2,3-dione
  • 2-amino-5-phosphopentanoic acid
  • Valine
  • Calcium