Fear extinction and BDNF: Translating animal models of PTSD to the clinic

• Type of Material: Article
• Authors: Raul Andero, Emory University; Kerry J Ressler, Emory University
• Language: English
• Date: 2012-07
• Publisher: Wiley: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2012 The Authors. Genes, Brain and Behavior © 2012 Blackwell Publishing Ltd and International Behavioural and Neural Genetics Society
• Final Published Version (URL): http://onlinelibrary.wiley.com/doi/10.1111/j.1601-183X.2012.00801.x/abstract
• Title of Journal or Parent Work: Genes, Brain and Behavior
• ISSN: 1601-1848
• Volume: 11
• Issue: 5
• Start Page: 503
• End Page: 512
• Grant/Funding Information: Support was provided by NIH (F32MH085443, R01DA01962), the Burroughs Wellcome Fund, and by the National Center for Research Resources P51RR165 and is currently supported by the Office of Research Infrastructure Programs/OD P51OD11132.
• Keywords: depression; brain derived neurotrophic factor; TrkB; fear; anxiety; Neurotrophic factor; PTSD
• Research Categories: Psychology, Cognitive; Biology, Neuroscience

Abstract

Brain-derived neurotrophic factor (BDNF) is the most studied neurotrophin involved in synaptic plasticity processes that are required for long-term learning and memory. Specifically, BDNF gene expression and activation of its high-affinity TrkB receptor are necessary in the amygdala, hippocampus and prefrontal cortex for the formation of emotional memories, including fear memories. Among the psychiatric disorders with altered fear processing there is Post-traumatic Stress Disorder (PTSD) which is characterized by an inability to extinguish fear memories. Since BDNF appears to enhance extinction of fear, targeting impaired extinction in anxiety disorders such as PTSD via BDNF signalling may be an important and novel way to enhance treatment efficacy. The aim of this review is to provide a translational point of view that stems from findings in the BDNF regulation of synaptic plasticity and fear extinction. In addition, there are different systems that seem to alter fear extinction through BDNF modulation like the endocannabionoid system and the hypothalamic-pituitary adrenal axis (HPA). Recent work also finds that the pituitary adenylate cyclase-activating polypeptide (PACAP) and PAC1 receptor, which are upstream of BDNF activation, may be implicated in PTSD. Especially interesting are data that exogenous fear extinction enhancers such as antidepressants, histone deacetylases inhibitors (HDACi) and D-cycloserine, a partial NMDA agonist, may act through or in concert with the BDNF-TrkB system. Finally, we review studies where recombinant BDNF and a putative TrkB agonist, 7,8-DHF, may enhance extinction of fear. These approaches may lead to novel agents that improve extinction in animal models and eventually humans.