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Retrieval of morphine‐associated context induces cFos in dentate gyrus neurons
Author(s) -
Rivera Phillip D.,
Raghavan Ramya K.,
Yun Sanghee,
Latchney Sarah E.,
McGovern MaryKatherin,
García Emily F.,
Birnbaum Shari G.,
Eisch Amelia J.
Publication year - 2015
Publication title -
hippocampus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.767
H-Index - 155
eISSN - 1098-1063
pISSN - 1050-9631
DOI - 10.1002/hipo.22393
Subject(s) - dentate gyrus , morphine , conditioned place preference , hippocampal formation , neuroscience , psychology , saline , context (archaeology) , pharmacology , chemistry , addiction , anesthesia , medicine , biology , paleontology
Addiction has been proposed to emerge from associations between the drug and the reward‐associated contexts. This associative learning has a cellular correlate, as there are more cFos+ neurons in the hippocampal dentate gyrus (DG) after psychostimulant conditioned place preference (CPP) versus saline controls. However, it is unknown whether morphine CPP leads to a similar DG activation, or whether DG activation is due to locomotion, handling, pharmacological effects, or—as data from contextual fear learning suggests—exposure to the drug‐associated context. To explore this, we employed an unbiased, counterbalanced, and shortened CPP design that led to place preference and more DG cFos+ cells. Next, mice underwent morphine CPP but were then sequestered into the morphine‐paired (conditioned stimulus+ [CS+]) or saline‐paired (CS−) context on test day. Morphine‐paired mice sequestered to CS+ had ∼30% more DG cFos+ cells than saline‐paired mice. Furthermore, Bregma analysis revealed morphine‐paired mice had more cFos+ cells in CS+ compared to CS− controls. Notably, there was no significant difference in DG cFos+ cell number after handling alone or after receiving morphine in home cage. Thus, retrieval of morphine‐associated context is accompanied by activation of hippocampal DG granule cell neurons. © 2014 Wiley Periodicals, Inc.