Female mice form an olfactory memory of male pheromones at mating; exp
osure to the pheromones of a strange male after that mating will block
pregnancy. The formation of this memory is mediated by the accessory
olfactory system, in which an increase in norepinephrine after mating
reduces inhibitory transmission of gamma-aminobutyric acid from the gr
anule cells to the mitral cells. This study shows that the activation
of mGluR2, a metabotropic glutamate receptor that suppresses the gamma
-aminobutyric acid inhibition of the mitral cells, permits the formati
on of a specific olfactory memory without the occurrence of mating by
infusion of mGluR2 agonists into the female's accessory olfactory bulb
. This memory faithfully reflects the memory formed at mating.