Ketamine accelerates fear extinction via mTORC1 signaling

Area of Science:

• Neuroscience
• Pharmacology
• Psychiatry

Background:

• Impaired fear extinction is a hallmark of post-traumatic stress disorder (PTSD).
• Glutamate pathways are implicated in traumatic memory and PTSD pathophysiology.
• Ketamine, an NMDA receptor antagonist, shows promise in rapidly reducing PTSD symptoms.

Purpose of the Study:

• To investigate the mechanisms of ketamine's action on fear conditioning, extinction, and renewal in a rodent model.
• To explore the role of mTORC1 signaling in the medial prefrontal cortex (mPFC) in ketamine's effects on extinction.

Main Methods:

• Rats underwent fear conditioning, followed by ketamine or saline administration.
• Subsequent extinction training was conducted over three days.
• Levels of mTORC1 and cFos in the mPFC were measured; effects of rapamycin and an AMPA receptor antagonist were assessed.

Main Results:

• Ketamine administration significantly enhanced fear extinction and produced long-lasting reductions in freezing behavior.
• Ketamine and extinction exposure increased mTORC1 levels in the mPFC.
• Inhibition of mTORC1 or AMPA receptors blocked ketamine's beneficial effects on extinction.

Conclusions:

• Ketamine facilitates fear extinction through mTORC1/protein synthesis-dependent mechanisms in the mPFC.
• These findings support ketamine's potential as a novel therapeutic for PTSD by enhancing neuronal circuit activity related to extinction.
• The study highlights the importance of glutamate and mTORC1 pathways in the treatment of PTSD.