Short CommunicationFear extinction in 17 day old rats is dependent on metabotropic glutamate receptor 5 signaling

•Positive allosteric modulation of mGlu5 facilitates extinction of conditioned fear in postnatal day (P) 17 rats, but not in P24 or adult rats.•Negative allosteric modulation of Glu5 impairs extinction of conditioned fear in P17 rats, but not in P24 or adult rats.•There is a developmental shift in the importance of mGlu5 signaling in extinction of conditioned fear.

We used pharmacological modulation of the mGlu5 receptor to investigate its role in the extinction of conditioned fear throughout development. In postnatal day (P) 17 rats, the positive allosteric modulator CDPPB facilitated, while the negative allosteric modulator MTEP impaired extinction. These drugs had no such effects on P24 or adult rats. These results establish a changing importance of mGlu5 in extinction of conditioned fear at distinct stages of development.