BDNF-dependent synaptic sensitization in midbrain dopamine neurons after cocaine withdrawal.

The neural mechanism underlying the relapse to drug use after drug withdrawal is largely unknown. We found that after withdrawal from repeated cocaine exposure, excitatory synapses onto dopamine neurons in the ventral tegmental area (VTA) of the rat midbrain became highly susceptible to potentiation by weak presynaptic stimuli, an effect requiring endogenous brain-derived neurotrophic factor-tyrosine kinase B (BDNF-TrkB) signaling. The elevated BDNF expression in the VTA after cocaine withdrawal may prime these synapses for potentiation by cue-associated activity, triggering drug craving and relapse.