Infralimbic BDNF/TrkB enhancement of GluN2B currents facilitates extinction of a cocaine-conditioned place preference.
Brain-derived neurotrophic factor (BDNF) regulates synaptic activity and behavioral flexibility, and reduction of BDNF strongly predicts psychiatric disorders and cognitive dysfunction. Restoration of BDNF-dependent activity could alleviate these impairments, but BDNF has limited clinical utility due to its pharmacokinetics. Here we demonstrate that activation of a primary BDNF target, the tropomyosin-related kinase B (TrkB) receptor, enhances the amplitude and prolongs the decay kinetics of N-methyl-d-aspartate receptor (NMDAR) currents in male rat infralimbic prefrontal pyramidal neurons. Moreover, these effects were prevented and reversed by blockade of NMDARs containing the GluN2B subunit. Our results show that this signaling cascade bidirectionally regulates extinction of a cocaine-induced conditioned place preference (CPP), a task that requires behavioral flexibility. Blockade of infralimbic TrkB receptors or GluN2B-containing NMDARs disrupted consolidation of extinction of the CPP. In contrast, extinction was strengthened by potentiation of TrkB receptor activity with infralimbic infusions of BDNF or systemic injections of 7,8 dihydroxyflavone (7,8DHF), the newly synthesized TrkB receptor agonist. The 7,8DHF-induced enhancement of extinction was prevented by infralimbic infusions of a GluN2B-specific receptor antagonist, demonstrating that TrkB receptor activation enhances extinction of cocaine-CPP via GluN2B-containing NMDARs. Together, infralimbic TrkB receptor activation strengthens GluN2B-containing NMDAR currents to support extinction learning. TrkB receptor agonists would therefore be useful as pharmacological adjuncts for extinction-based therapies for treatment of psychiatric disorders associated with reduced BDNF activity.
Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201-0413.
James M
JM
Otis
Michael K
MK
Fitzgerald
Devin
D
Mueller
D000818:Animals; D001245:Association Learning / Q000187:drug effects / Q000502:physiology; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology*; D003042:Cocaine / Q000008:administration & dosage*; D003216:Conditioning, Operant / Q000187:drug effects* / Q000502:physiology; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage*; D005108:Extinction, Psychological / Q000187:drug effects* / Q000502:physiology; D005239:Fear / Q000187:drug effects / Q000502:physiology; D044950:Flavanones / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D051381:Rats; D020813:Receptor, trkB / Q000819:agonists*; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D012646:Self Administration
C478869:7,8-dihydroxyflavanone; D019208:Brain-Derived Neurotrophic Factor; D018765:Dopamine Uptake Inhibitors; D044950:Flavanones; C121001:NR2B NMDA receptor; D016194:Receptors, N-Methyl-D-Aspartate; D020813:Receptor, trkB; D003042:Cocaine
NR2B-containing NMDA receptor; TrkB receptor; brain-derived neurotrophic factor; extinction learning; medial prefrontal cortex; patch-clamp electrophysiology