The guidepost neurons for the lateral olfactory tract, which are called lot cells, are the earliest-generated neurons in the neocortex. They migrate tangentially and ventrally further down this tract, and provide scaffolding for the olfactory bulb axons projecting into this pathway. The molecular profiles of the lot cells are largely uncharacterized. We found that lot cells specifically express metabotropic glutamate receptor subtype-1 at a very early stage of development. This receptor is functionally competent and responds to a metabotropic glutamate receptor agonist with a transient increase in the intracellular calcium ion concentration. When the glutamatergic olfactory bulb axons were electrically stimulated, lot cells responded to the stimulation with a calcium increase mainly via ionotropic glutamate receptors, suggesting potential neurotransmission between the axons and lot cells during early development. Together with the finding that lot cells themselves are glutamatergic excitatory neurons, our results provide another notable example of precocious interactions between the projecting axons and their intermediate targets.
Copyright © 2012 Wiley Periodicals, Inc.