title: Synaptic modulation via basolateral amygdala on the rat hippocampus-medial prefrontal cortex pathway in fear extinction.
abstract: The present study elucidated the functional role of modulatory effects of basolateral amygdala (BLA) on synaptic transmission in the rat hippocampus-medial prefrontal cortex (mPFC) pathway, compared with the hippocampal dentate gyrus (DG). Exposure to conditioned fear stress (CFS) or prior BLA activation enhanced tetanus-induced long-term potentiation (LTP) in DG. A similar synaptic response was found by low frequency stimulation (LFS) prior to tetanus. In mPFC, they did not affect LTP, but prior BLA activation, as well as pretreatment with the N-methyl-d-aspartate (NMDA)-receptor antagonist MK-801 (0.1 mg/kg, i.p.), suppressed LFS-primed LTP. This BLA-mediated synaptic pattern was mimicked by synaptic changes observed in the fear extinction process; prior BLA activation suppressed the synaptic potentiation responsible for extinction retrieval and attenuated decreases in fear-related freezing behavior. These data suggest that LFS-primed LTP in mPFC is related to the neural basis of extinction. Extinction-related synaptic potentiation did not occur in a juvenile stress model that exhibited extinction deficit. In addition, LFS-primed LTP was suppressed in this model, which was reversed by the NMDA-receptor agonist d-cycloserine (15 mg/kg, i.p.). These findings suggest that modulatory effects of BLA on synaptic function in the hippocampus-mPFC pathway play a significant role in fear extinction in rats.
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Science, Health Sciences University of Hokkaido, Japan.
authors.forename: Sumitaka
authors.initials: S
authors.lastname: Inoue
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Kamiyama
authors.forename: Machiko
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Yanagawa
authors.forename: Sachiko
authors.initials: S
authors.lastname: Hiraide
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Saito
authors.forename: Kei-ichi
authors.initials: K
authors.lastname: Shimamura
authors.forename: Hiroko
authors.initials: H
authors.lastname: Togashi
mesh_terms: D000679:Amygdala / Q000502:physiology*; D000818:Animals; D003213:Conditioning, Psychological / Q000502:physiology; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004558:Electric Stimulation; D005071:Evoked Potentials; D005108:Extinction, Psychological / Q000187:drug effects / Q000502:physiology*; D005239:Fear / Q000502:physiology* / Q000523:psychology*; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000494:pharmacology; D017774:Long-Term Potentiation / Q000187:drug effects; D008297:Male; D023421:Models, Animal; D020534:Parahippocampal Gyrus / Q000502:physiology; D017397:Prefrontal Cortex / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists / Q000037:antagonists & inhibitors; D013315:Stress, Psychological; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D006843:Hydrocarbons, Chlorinated; D016194:Receptors, N-Methyl-D-Aspartate; D016291:Dizocilpine Maleate; C007792:Fumigant 93