Elevated BDNF after Cocaine Withdrawal Facilitates LTP in Medial Prefrontal Cortex by Suppressing GABA Inhibition

SummaryMedial prefrontal cortex (mPFC) is known to be involved in relapse after cocaine withdrawal, but the underlying cellular mechanism remains largely unknown. Here, we report that after terminating repeated cocaine exposure in rats, a gradual increase in the expression of brain-derived neurotrophic factor (BDNF) in the mPFC facilitates activity-induced long-term potentiation (LTP) of excitatory synapses on layer V pyramidal neurons. This enhanced synaptic plasticity could be attributed to BDNF-induced suppression of GABAergic inhibition in the mPFC by reducing the surface expression of GABAA receptors. The BDNF effect was mediated by BDNF-TrkB-phosphatase 2A signaling pathway. Downregulating TrkB expression bilaterally in the mPFC reduced the locomotor hypersensitivity to cocaine 8 days after cocaine withdrawal. Thus, elevated BDNF expression after cocaine withdrawal sensitizes the excitatory synapses in the mPFC to undergo activity-induced persistent potentiation that may contribute to cue-induced drug craving and drug-seeking behavior.

► BDNF expression is elevated gradually in rat mPFC after cocaine withdrawal
► Elevated BDNF facilitates LTP through TrkB signaling
► BDNF-TrkB-PP2A signaling causes reduction of GABAergic inhibition
► Downregulating TrkB reduces locomotor hypersensitivity to cocaine after withdrawal