Postnatal development of neurotransmitter systems and their relevance to extinction of conditioned fear

•Relapse-resistant extinction in juvenile rodents may be due to high NMDA-NR2B, mGlu5, and/or nicotinic receptor signaling in the amygdala.•Extinction deficit in adolescence may be due to low NMDA-NR2B, and/or low D2R relative to D1R signaling in the PFC.•High corticotropin releasing factor, and/or reduced cannabinoid signaling in the amygdala may be related to impaired extinction in adolescence.•Changes in the localization of oxytocin receptors in the amygdala may explain transition from effective to ineffective extinction across development.